Cell Adhesion, Polarity, and Epithelia in the Dawn of ... - CiteSeerX [PDF]

Physiol Rev 84: 1229 –1262, 2004; 10.1152/physrev.00001.2004.

Cell Adhesion, Polarity, and Epithelia in the Dawn of Metazoans M. CEREIJIDO, R. G. CONTRERAS, AND L. SHOSHANI Center for Research and Advanced Studies (CINVESTAV), Me´xico, Mexico

I. Introduction A. For almost a century transepithelial transport was a hard-to-believe hypothesis B. The puzzle of the first metazoan II. Model Systems of Transporting Epithelia III. The Na⫹-K⫹-ATPase A. The ␣-subunit B. The ␤-subunit C. ␣/␤-Subunit interactions D. The ␥-subunit E. Assembly and delivery of the Na⫹-K⫹-ATPase F. The triggering effect of Ca2⫹ G. The polarized distribution of Na⫹-K⫹-ATPase IV. Tight Junctions A. Structure B. Transmembrane proteins C. Membrane-associated proteins D. Lipids E. Diversity arising from processing TJ proteins as well as by the expression of several isoforms F. Proteins that can localize to the nucleus and adhesion complexes G. Phosphorylation in TJ assembly and function H. Biogenesis V. Septate Junctions VI. Adherens Junctions A. Structure and function B. Relationships between adherens and occluding junctions VII. Polarity A. The transporting epithelial phenotype B. Polarity and the TJ C. Na⫹-K⫹-ATPase, cell attachment, and the position of the TJ VIII. Evolution of the Epithelial Vectorially Transporting Phenotype A. Evolution of the Na⫹-K⫹-ATPase B. Evolution of junction proteins IX. The Dawn of Metazoans and Transporting Epithelia A. The “thrifty sponge” B. Very flat organisms C. The “mare nostrum” metazoans X. Na⫹-K⫹-ATPase and Cell Adhesion A. Role of the ␤-subunit in cell attachment B. (P3 A), a pump (P) adhesion (A) mechanism

1230 1230 1230 1231 1232 1233 1233 1234 1234 1235 1235 1235 1236 1238 1238 1239 1239 1240 1240 1240 1241 1241 1242 1242 1242 1243 1244 1244 1244 1244 1245 1246 1247 1247 1248 1248 1248 1248 1248

Cereijido, M., R. G. Contreras, and L. Shoshani. Cell Adhesion, Polarity, and Epithelia in the Dawn of Metazoans. Physiol Rev 84: 1229 –1262, 2004; 10.1152/physrev.00001.2004.—Transporting epithelia posed formidable conundrums right from the moment that Du Bois Raymond discovered their asymmetric behavior, a century and a half ago. It took a century and a half to start unraveling the mechanisms of occluding junctions and polarity, but we now face another puzzle: lest its cells died in minutes, the first high metazoa (i.e., higher than a sponge) needed a transporting epithelium, but a transporting epithelium is an incredibly improbable combination of occluding junctions and cell polarity. How could these coincide in the same individual organism and within minutes? We review occluding www.prv.org

0031-9333/04 $15.00 Copyright © 2004 the American Physiological Society

1229

1230

CEREIJIDO, CONTRERAS, AND SHOSHANI

junctions (tight and septate) as well as the polarized distribution of Na⫹-K⫹-ATPase both at the molecular and the cell level. Junctions and polarity depend on hosts of molecular species and cellular processes, which are briefly reviewed whenever they are suspected to have played a role in the dawn of epithelia and metazoan. We come to the conclusion that most of the molecules needed were already present in early protozoan and discuss a few plausible alternatives to solve the riddle described above.

I. INTRODUCTION The study of epithelia always posed formidable conundrums. The first one, briefly described below, arose a century and a half ago when it was discovered that these tissues have a spontaneous electrical potential between the outer and the inner side. Today, even when biological asymmetries (referred to as “polarity”) are still subject to intense research, we are no longer stuck in a puzzling situation nor foresee conflicting aspects. The second riddle is posed by the origin of epithelia as part of the emergence of metazoans. Since its cells perish for lack of nutrients or excess of metabolic wastes, a metazoan higher than a sponge exchanges nutrients and wastes with an internal milieu, which in turn exchanges them through transporting epithelia, but a transporting epithelium is in itself a highly elaborated combination of occluding junctions and polarized mechanisms. Therefore, the origin of the first metazoan would have depended on the incredibly improbable coincidence, in the same individual and within minutes, of an elaborated epithelium with occluding junctions and polarity. We propose that the somewhat baffling episode consisted of a combination of different species of attaching molecules and even fundamental polarizing processes that were already available in unicellulars. This article is therefore devoted to update some aspects of cell attachment and polarity that might have participated in the dawn of transporting epithelia and metazoans. A. For Almost a Century Transepithelial Transport Was a Hard-To-Believe Hypothesis In the second half of the 19th century Emile Du Bois Raymond demonstrated that a frog skin separating two saline solutions exhibits a spontaneous electrical potential difference across it. G. Galeotti (166, 167) proposed that this potential could be explained by assuming that the epithelium has a higher Na⫹ permeability in the inward than in the outward direction. This explanation was not accepted because it would be in violation of the first and second laws of thermodynamics (66, 72). A second argument, seeking a source of energy, proposed that it would be provided by the metabolism of the cells, but was also refuted because, according to Curie’s principle, phenomena of different tensorial order cannot be coupled, i.e., Na⫹ transport is a vectorial phenomenon (it occurs in Physiol Rev • VOL

the outside to inside direction) and cannot be driven by a scalar phenomenon (in those days chemical reactions were assumed to be scalar and therefore could not be expected to proceed in a given direction of the space). Half a century later, Hans Ussing devised electric and tracer methods to unambiguously demonstrate that the frog skin can actually transport a net amount of Na⫹ in the inward direction and in the absence of an external electrochemical potential gradient (456). Of course, this demonstration, confirmed thereafter in hundreds of laboratories, prompted a closer look at the arguments that had stood in the way of accepting that metabolism can drive Na⫹ transport. To start with, a protein like Na⫹-K⫹ATPase cannot interact with Mg2⫹, Na⫹, K⫹, ATP, and ouabain just anywhere on its surface, but at very specific sites located either on the outer or on the inner side of the cell membrane, but not both, i.e., this enzyme is vectorial at the microscopic level. Yet, when studied in a solution where millions of molecules point in all directions, vectoriality is lost. But in the orderly molecular orientation of a cell membrane, Na⫹-K⫹-ATPase is anisotropic both at the microscopic and at the macroscopic level. In turn, De Donder and van Rysselberghe (117) proved that chemical affinity can constitute a driving force, Onsager (340, 341) demonstrated that all fluxes and all forces present in a system can be, in principle, coupled, and Kedem (245) demonstrated that the flux of a given ion can be coupled to metabolism, so the split of ATP into ADP plus Pi can, in fact, drive the net flux of Na⫹. In keeping with the idea that gradients and fluxes of different substances can be coupled, it was later found that the Na⫹ gradient originated by the Na⫹-K⫹-ATPase can also propel the unidirectional fluxes of sugars, amino acids, Cl⫺, Ca2⫹, H⫹, etc., via co- and countertransporters. B. The Puzzle of the First Metazoan Life depends on an intense and highly selective exchange of substances between cells and their environment. In the case of single cells living in the sea, this environment behaves as an infinite reservoir. When cells belong instead to a higher metazoan organism, they exchange with a very thin layer of interstitial milieu that would be quickly spoiled were it not for a circulatory apparatus that constantly restores nutrients and takes away waste products by carrying them to and from large

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

areas of epithelia (intestinal, renal, gills, etc.) where they are finally exchanged with the external environment. Even when a primeval metazoan might have been a small organism contained within a single type of epithelium, it required some sort of sealing between its cells, and these cells should have had vectorial transport. Therefore, the emergence of first metazoans higher than a sponge poses a paradox, because somatic cells gathered in a restricted space required a transporting epithelium to exchange substances with the external environment, but the first transporting epithelium depended in turn on the highly improbable coincidence, within a few minutes and in the same organism, of three novelties: 1) assembly of the multicellular organism itself, 2) the establishment of occluding junctions between epithelial cells, and 3) a polarized distribution of transport mechanisms in the membrane of these cells. In this review we explore the possibility that metazoans, occluding junctions, and vectorial transport appeared as manifestations of specific types of binding between certain molecular species, as well as between epithelial cells. The argument requires a brief description of the preparations developed to investigate the development of the so-called “epithelial transporting phenotype, ” as well as a review of Na⫹-K⫹-ATPase and cell junctions, concentrating on those properties that involve specific bindings between molecules as well as between cells.

1231

II. MODEL SYSTEMS OF TRANSPORTING EPITHELIA Most studies to evaluate unidirectional fluxes across the apical and the basolateral membrane of epithelial cells (Fig. 1) followed black box approaches (Fig. 2) (60, 64, 113, 211), but in spite of affording valuable information on overall epithelial processes (46, 65, 67, 68, 71, 73, 233, 318, 367, 369, 386), these approaches lacked the necessary resolution to study their cellular and molecular basis and, more specifically, junctions and polarity. Furthermore, black box methods could only be applied to mature epithelia where junctions and asymmetry are already established. Therefore, entirely different methods were required. Oxender and Christensen (343) attempted to assemble an artificial epithelium by sandwiching single Ehrlich ascites cells between Millipore filters separating two chambers. However, these cells lacked an intrinsic asymmetry, remained oriented at random, did not attach, and no asymmetry of the whole preparation was detected. Further attempts used epithelial cells dislodged from epithelia through treatment with Ca2⫹ chelants and hydrolyzing enzymes. The first step was to separate the epithelium of a frog skin (387) and show that it preserves the overall properties of dissected epithelia. Therefore, the second step was to mince the epithelium, dislodge the cells, and investigate whether these maintain a satisfac-

FIG. 1. Position and structure of diverse cell junctions. Two neighboring epithelial cells have their apical domain towards the outside, with the basal domain contacting the inside through an extracellular matrix and the lateral domains contacting each other. Location of the main junctions mentioned in this review are indicated by squares and numbered. Cartoons at the bottom left depict the transmembrane molecules of claudin and E-cadherin, which are the most representative of tight (occludens) and adherens junctions among many others. Claudin has 4 transmembrane domains, and E-cadherin just 1. Both termini of claudin are intracellular, whereas only the COO⫺ of Ecadherin is intracellular. The extracellular domain of E-cadherin has 5 repeats and is glycosylated (small green circles). No molecular details of the macula adherens (desmosome, Ref. 170) nor the gap junction are represented, as these are not discussed in the text. The conexons of the gap junctions (pink) communicate the intracellular compartment of the two neighboring cells.

Physiol Rev • VOL

84 • OCTOBER 2004 •

www.prv.org

1232

CEREIJIDO, CONTRERAS, AND SHOSHANI

FIG. 2. Early black box methods to study unidirectional fluxes through the apical or basal domain of epithelial cells. A frog skin is mounted as a diaphragm between two halves of a Lucite chamber with a rectangular exposed area. Ringer solution is injected in 48 s; the outer one (apical) has 24Na, so when it reaches the top the lowest part of the epithelium has been exposed 48 s, and the rest a fraction of this time. The skin is quickly frozen (liquid nitrogen) and washed, and the exposed area is sliced. The 24Na in each piece is counted. The slope of the curve is used to calculate J12. Figure at the bottom right represents an epithelial cell with the 4 unidirectional fluxes involved in transepithelial Na flux. Further procedures (not detailed) can be used to calculate the other Jij. [Redrawn from Cereijido and Rotunno (72).]

tory ionic steady state and responded to ouabain, amiloride, changes in temperature, or have other evidences that cells retained the basic properties of natural epithelia (500, 501). Finally, the third step was to seed the cells on glass or Millipore filters to form a sort of artificial epithelium. Unfortunately, cells performed poorly in culture, detached easily, died soon, and prompted us to try established cell lines. We chose the MDCK line derived by Madin and Darby (288) from canine kidney, which was generally used to grow viruses, because it retained sufficient differentiation as to secrete fluid (276). We cultured these cells on translucent supports (a nylon cloth coated with collagen) on which cells can easily be observed (69, 70, 72, 75), or nitrocellulose filters. A similar preparation was developed by Misfeldt et al. (315). This approach gave us an opportunity to study the development of the transporting epithelia phenotype. Thus we used it to study the synthesis, assembly, and sealing of tight junctions (TJs) (69, 74, 75, 78, 145, 183, 297), as well as the polarity of Na⫹-K⫹-ATPase (61, 62, 96, 102); Enrique Rodriguez-Boulan introduced the use of viruses that bud either apically (e.g., Flu) or basolateraly (e.g., stomatitis) to track the fate of specific proteins during apical or basolateral polarity (283, 284, 379 –382), and Carlos A. Rabito analyzed the onset of polarized cotransporters (368, 370, 371). M. Taub perfected the approach by developing totally defined culture media (440 – 442), and complementary procedures were refined to open and reseal the TJs by removing and restoring Ca2⫹ (69, 97, 101, 184, 186), follow the cascades of phosphorylation involved (20, 21, 85), the role of the cytoskeleton (311, 312), the participation of Physiol Rev • VOL

protein synthesis and sorting (196, 376, 379, 381), the polarized distribution of ion channels (317, 359, 360, 361, 421, 439), the involvement of E-cadherin (199 –201), the effect of agents that induce differentiation (280), and the vectorial movement of receptors (302). A distinct advantage of cultured monolayers is derived from the possibility of labeling beforehand a given cell type, and then mixing them with other types from different epithelia and even different animal species (98, 103, 185), and other characteristics illustrated below and reviewed in Cereijido (56) and Cereijido and Anderson (58).1 In addition to the preparation just described, the information discussed in this review was obtained with suspended clumps and cysts of epithelial cells (465), yeasts, Caenorhabditis elegans and Drosophila (479), fertilized eggs, and the first stages of development from egg to embryo (151). III. THE Naⴙ-Kⴙ-ATPase The Na⫹-K⫹-ATPase is not the only pump known today, yet for many years it was the almost exclusive focus of attention, and today is recognized to act as the star in the net transfer of a wide variety of substances across epithelia. The Na⫹-K⫹-ATPase is a member of the family of P-type ATPases. ATP hydrolysis by these ATPases includes a step of transfer of the terminal phos1 For a vignette on the development of this model system, see Current Contents 32: 46, 1989 and Physiologist 46: 114 –115, 2003.

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

phoryl group of ATP onto the carboxyl group of an aspartic acid residue that is located in the active site of the enzyme (42). Among the ions transported by these type of pumps are protons, calcium, sodium, potassium, and heavy metals such as manganese, iron, copper, and zinc (418). The formation of a phosphorylated intermediate during the catalytic cycle is a characteristic of P-type ATPases that distinguishes them from V-ATPases and F-ATPases (347, 348). The Na⫹-K⫹-ATPase is a heteromultimeric membrane enzyme constituted by ␣-, ␤-, and ␥-subunits. A. The ␣-Subunit The 112-kDa ␣-subunit, often called the catalytic subunit, bears the site for ATP hydrolysis; has the binding sites for Na⫹, K⫹, and cardiac glycosides; and is homologous to the Ca2⫹-ATPase of the sarcoplasmic reticulum (SERCA) whose 2.6-A˚ resolution structure was recently reported by Toyoshima et al. (449). Since the first cloning and sequencing of a Na⫹-K⫹ATPase ␣1-subunit (413), hydropathy analyses have deduced 10 transmembrane crossings (241). A combination of heterologous expression and site-directed chemical labeling of cysteine mutants found five exposed extracellular loops and showed that both termini are intracellular (217). The high-resolution structure of SERCA was compared in detail to a Na⫹-K⫹-ATPase projection (429) and supported the idea that the Na⫹-K⫹-ATPase structure is very similar to the structure of SERCA (277). There are three main intracellular structures: a large central loop between M4 and M5 (210) composed of ⬃430 amino acid residues, a long NH2-terminal tail of ⬃90 amino acids, and an intracellular loop of ⬃120 residues between M2 and M3. These form the N or nucleotide-binding domain, the P or phosphorylation domain, and the A or actuator domain (449). 1. ␣-Subunit isoforms Four isoforms of the ␣-subunit occur in mammals: ␣1, ␣2, ␣3, and ␣4, that exhibit somewhat different properties in terms of cation binding (231) and are expressed in a tissue-specific and developmentally regulated manner. While the ␣1-isoform is expressed in every tissue, ␣2 is limited largely to skeletal muscle, heart, and brain. The ␣3-isoform is expressed in brain and ovary, and ␣4 is exclusive of sperm and its precursor cells (41, 406, 481). The ␣2- and ␣3-isoforms appear early in brain development, and around birth in heart and skeletal muscle. Na⫹-K⫹-ATPase isoform expression can also be differentially regulated by hormones (214, 342), and ␣-isoform genes contain 59 specific sequences that are potential trans-acting factors and hormone binding sites (385). Animals lacking the ␣1-isoform gene do not develop past the Physiol Rev • VOL

1233

blastocyst stage (282). Yet, ␣2-isoform-deficient animals develop to term, as expected, since it is not expressed in early embryonic development. Interestingly, these animals were either born dead or died within the first few minutes after birth due to failure in the neuronal activity of the breathing center in the neonate (321). B. The ␤-Subunit This subunit is part of the Na⫹-K⫹- and H⫹-K⫹ATPases but is not included in other P-type ATPases; for example, Ca2⫹-ATPase of both plasma membrane and sarcoplasmic reticulum do not have it. It is composed of ⬃370 amino acids, with the first 30 exposed to the cytosol, and 300-fold to form the extracellular portion that has 3 disulfide bonds. There are 3 N-glycosylation consensus sequences (NXS or NXT) in the extracellular domain (249, 400). The polypeptide chain of the ␤-subunit weighs 32–35 kDa, and when fully glycosylated can reach an overall apparent molecular mass of 55– 60 kDa. Analysis of ␤-subunits in which the disulfide bonds were removed through substitution in baculovirus-infected insect cells, reveals that the S-S bridges are not important for assembling the heterodimer, yet they are required for membrane targeting (171, 272). Recent studies using heterologous expression suggest that substitution of the essential asparagine residues prevents glycosylation, but this has little if any effect on catalytic activity (30). The ␤-subunit has been identified as a factor responsible for cell adhesion in nervous tissue (180). The activity of Na⫹-K⫹-ATPase can be influenced by lectins, in particular, concanavalin A (428), and galectins (various lectins of animal origin), some of which affect cell adhesion (335) and provide in this way signal transmission to the catalytic subunit. 1. ␤-Subunit isoforms Three ␤-isoforms can be attributed to Na⫹-K⫹ATPase in mammals (␤1, ␤2, and ␤3), and a fourth to gastric H⫹-K⫹-ATPase (␤HK). Significantly, for the nongastric H⫹-K⫹-ATPase, no specific ␤-subunit has been identified. X-K-ATPase ␤-isoforms exhibit only ⬃20 –30% overall sequence identity but share several structural features. ␤-Isoforms exhibit a tissue-specific distribution with ␤1 of Na⫹-K⫹-ATPase being expressed ubiquitously, ␤2 mainly in the heart, skeletal muscles, and glial cells, and ␤3 in many tissues (for review, see Ref. 42). Recently, a novel member of the ␤-subunit family has been identified (␤m) which shares common structural features and signature motifs with X-K-ATPase ␤-isoforms (355). Despite the similarities with X-K-ATPase ␤-isoforms, ␤m has also some atypical characteristics. First, it contains two long glutamate-rich regions in the cytoplasmic NH2 terminus that are not present in X-K-

84 • OCTOBER 2004 •

www.prv.org

1234

CEREIJIDO, CONTRERAS, AND SHOSHANI

ATPase ␤-subunits (357). Second, based on results of cell fractionation (356) and on its state of glycosylation (357), ␤m appears to be concentrated in the sarcoplasmic reticulum; in contrast, X-K-ATPase ␤-subunits are predominantly found at the plasma membrane. Recent studies reveal that ␤m is a resident of the endoplasmic reticulum, which does not act as a chaperone for the maturation of any of the known X-K-ATPase ␤-subunits, thus representing a protein functionally distinct from other members of the ␤-subunit family (108). The ␤2-isoform is strongly expressed in the brain and moderately in the spleen (181). It was identified as an adhesion molecule on glia (AMOG) mediating adhesion between neurons and astrocytes (8, 9). Sequence analysis of AMOG identified it as a homolog of the ␤1-subunit (180). The dual function of the ␤2-subunit in cell recognition and ion transport has been hypothesized to couple cell recognition with regulation of the ionic milieu (180). In a recent work Okamura et al. (339) analyzed a complete list of the P-type ATPase genes in Caenorhabditis elegans and Drosophila melanogaster. The branching points and the inferred evolutionary rates of the invertebrate ␤-subunits suggest that D. melanogaster possesses two distinct types of ␤-subunits, one type (␤1, ␤2, and ␤3) closer to the vertebrate ␤-subunits and the other type (␤4, ␤5, and ␤6) sharing more homology with C. elegans ␤-subunits. The tissue-specific expression patterns of two of the Drosophila melanogaster genes for the ␤-subunit have been studied (Nervana 1 and 2; Nrv). Nrv1 produces a single ␤-subunit isoform expressed primarily in muscle tissue, whereas Nrv2 codes for two different isoforms (2.1 and 2.2) expressed in the nervous system. The tissue-specific expression of each Nrv gene is independently regulated by the cis-elements present in the 5⬘-flanking region. The Nrv2 5⬘-flanking DNA directs expression exclusively to the nervous system, whereas Nrv1 5⬘-flanking DNA directs expression primarily in muscle tissue (490). C. ␣/␤-Subunit Interactions The subunits of Na⫹-K⫹-ATPase are synthesized independently in the endoplasmic reticulum and assembled in this organelle. Detergent solubilized ␣␤-heterodimers of Na⫹-K⫹-ATPase are able to carry out normal Na⫹-K⫹ATPase activity (136, 137). However, without the ␤-subunit the ␣-subunit does not exhibit a detectable activity (438) and is rapidly degraded (2, 174). The ␤-subunit may be involved in stabilizing the correct transmembrane folding of the ␣-subunit (2, 172, 173, 399). Amino acid residues located in the proximity to the COOH-terminal fragment of the ␤-subunit appear to participate in the association between the ␣-subunit and the ␤-subunit (29, 95), as does its transmembrane fragment, which interacts with transmembrane fragments M9-M10 of the ␣-subunit (396). Physiol Rev • VOL

In the extracellular M7M8 loop of the ␣-subunit, a sequence of 26 amino acid residues between N894 and A919 interacts to produce the associated ␣/␤-complexes (277), yet in insect cells, which lack endogenous subunits, infection with baculovirus particles with only ␤-subunits results in the expression of ␤, which traffics readily to the plasma membrane (171). The expression of ␣- and ␤-subunit isoforms follows a tissue-specific pattern (291, 296, 402). While genes encoding ␣-subunits have a similarity above 90% (412, 413), the ones encoding ␤-isoforms only share 39 – 48% sequence identity (291, 400). The ␣3- and ␤1-isoforms are exclusive for the axon, and ␣2-and ␤2-isoforms are exclusive for the Schwann cell, although axonal contacts regulate ␣2- and ␤2-isoform expressions (244). However, multiple ␣- and ␤-isoforms can be expressed simultaneously in the same cell type (52, 306, 471), suggesting that they have distinct functions. Conversely, in heterologous expression systems, all Na⫹-K⫹-ATPase ␤-isoforms can associate with all Na⫹-K⫹-ATPase ␣-isoforms and produce functionally active ␣/␤-complexes with slightly different transport and pharmacological properties (109, 229). Moreover, Na⫹-K⫹-ATPase ␣-subunits can produce stable complexes with H⫹-K⫹-ATPase ␤-subunit which are, however, partially inactive (131, 209, 213). Then again, the H⫹-K⫹-ATPase ␣-subunit does not associate with the Na⫹-K⫹-ATPase ␤1-isoform (189, 466). So far, little is known about the determinants that govern the specificity of X-K-ATPase ␣/␤-interactions in cells expressing multiple ␣- and ␤-isoforms. D. The ␥-Subunit This subunit is a small membrane protein that associates with Na⫹-K⫹-ATPase in the kidney and potentially in the placenta and the mammary gland (11, 31, 430). It belongs to the FXYD family, a group of small (7.5–19 kDa) single-span membrane proteins, characterized by the presence of the FXYD motif in the extracellular domain, and that includes phospholemman, channel-inducing factor (CHIF), and other peptides (430). The ␥-subunit is not required for catalytic activity (207) but modulates Na⫹ pump function by changing the affinity for ATP, Na⫹, and/or K⫹ (10, 366, 446, 447). It is synthesized from a gene with two different promoter regions that provide differential expression of the two splice variants known (264, 430). The ␥-subunit or other proteins of the FXYD family, namely, phospholemman, CHIF, PLMS (a dogfish shark FXYD family member), and FXYD7, interact with Na⫹-K⫹ATPase and/or modulate its activity, modifying the transport capacity of epithelia in kidney, shark rectal gland, and choroid plexus, as well as the function of other tissues in the central nervous system (31, 32, 108, 146, 289, 445). The ␥-subunit and homologous proteins may potentially increase the variety of the Na⫹ pumps.

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

E. Assembly and Delivery of the Naⴙ-Kⴙ-ATPase Occluding junctions and apical/basolateral polarity are lost upon harvesting with trypsin and EDTA, but regained in a few hours of reseeding at confluence and in the presence of Ca2⫹. If cells are instead deprived of this ion and maintained in suspension with a stirrer, the transporting phenotype does not develop. The addition of soluble collagen prompts cells to expose more specific binding sites, but cells still remain unpolarized and fail to form TJs (395). Ca2⫹ promotes the formation of clumps, in which suspended cells take each other as substrate, form TJs and polarize, orienting the apical domain towards the outer side of the clump (465). Collagen added under this condition binds to the apical membrane and causes an inversion of polarity and a relocation of TJs that, by the way, show the dynamic nature of these structures (25, 303). When cells are plated in the presence of Ca2⫹ but this ion is removed after allowing 20 – 40 min for attachment to the substrate, the relatively small fraction of Na⫹-K⫹ATPase and ion channels expressed at the plasma membrane cells is not polarized, and these molecules, as well as TJ-associated molecules, remain trapped in intracellular membrane vesicles (96, 286, 361, 395). Ca2⫹ added at this time triggers polarization and junction formation in a few hours, a maneuver called “Ca2⫹ switch” (184). However, the presence of this ion cannot trigger by itself the development of the transporting epithelial phenotype, as cell-cell contacts are also required (317, 411, 439). F. The Triggering Effect of Ca2ⴙ 1. Extracellular events Ca2⫹ acts primarily on the extracellular side (97, 100, 101, 186) as indicated by 1) an extracellular Ca2⫹ concentration of 0.1 mM, which suffices to trigger junction formation and polarization, does not increase the level of cytosolic Ca2⫹ (14 ⫾ 8 nM) that was reduced as a consequence of the preincubation without this ion (20 ⫾ 8 nM); 2) La3⫹ blocks Ca2⫹ penetration, but because of its low affinity for the extracellular repeats of E-cadherin (see below), does not prevent this ion from triggering from the outside, either junction formation or polarization; 3) Cd2⫹ instead blocks both Ca2⫹ influx and the development of the transporting phenotype (100). The observation that extracellular Ca2⫹ is sufficient to trigger polarization and junction formation does not exclude that the subsequent penetration of the ion into the cytoplasm would produce a series of additional phenomena (327). Likewise, E-cadherin appears to have a large number of cellular roles besides that of promoting and maintaining TJs (495). Physiol Rev • VOL

1235

2. Intracellular events Once Ca2⫹ binds to the extracellular repeats of Ecadherin, a signal is transduced via two different G proteins, a protein kinase C (PKC), a phospholipase C (PLC), calmodulin, and mitogen-activated protein kinase (MAPK), triggering the development of the epithelial transporting phenotype (20, 21, 79, 184). The assembly and sealing of TJs occurs so quickly that a fraction of the Na⫹-K⫹ATPase is trapped on the apical side but is thereafter removed from this location (96). The polarized insertion of Na⫹-K⫹-ATPase triggered by Ca2⫹ can be blocked with inhibitors of protein synthesis, yet the proteins whose synthesis is required are neither the ␣- nor the ␤-subunits of Na⫹-K⫹-ATPase (96). G. The Polarized Distribution of Naⴙ-Kⴙ-ATPase The Na⫹-K⫹-ATPase of epithelial cells serves two different but integrated roles. The first is the translocation of ions across the plasma membrane as in other cell types (417, 418). The second stems from its expression in only one pole of the cells, in such a way as to carry the translocation of Na⫹ across the whole epithelium as proposed by Koeffoed-Johnson and Ussing (252). In turn, a combination between the polarized distribution of Na⫹K⫹-ATPase, specific ionic permeabilities, and the polarized expression of co- and countertransporters drives the net transport of other solutes across the whole epithelium (111, 112, 405). In keeping with these roles, Na⫹-K⫹ATPase is found to reside on the basolateral surface in most epithelial cells (134, 135, 139, 242). In a few other epithelial cells such as those of the choroid plexus (484), retinal pigment epithelium (204, 422), and cockroach salivary gland (236), this enzyme is expressed on the opposite side of the cells, but always in a polarized manner. Koefoed-Johnsen and Ussing (252) conceived their model on the basis of the macroscopic asymmetries of the frog skin (electrical potential, currents, and net ion transport) and represented epithelial cells as simple rectangles where the pump was assumed to be on the inner facing barrier, that would correspond to the basal side of a more realistic picture of the cell (Fig. 1). Yet in model systems of MDCK, either as monolayer (61, 62, 96, 98, 102) or as cysts (465), Na⫹-K⫹-ATPase is not expressed on the basal side, but restricted to the lateral plasma membrane facing the intercellular spaces. For the macroscopic parameters mentioned above, it is irrelevant whether the pump is located at the basal or at the lateral side, but as we shall discuss below, the expression on the lateral side may be crucial for the polarized distribution of the pump, which is the basis of the whole asymmetric behavior of epithelial cells. Newly synthesized Na⫹-K⫹-ATPase is directly addressed to the basolateral membrane domain in MDCK

84 • OCTOBER 2004 •

www.prv.org

1236

CEREIJIDO, CONTRERAS, AND SHOSHANI

cells (54, 188, 189). This targeting seems to be determined by the impossibility of this enzyme to board the glycosphingolipid (GSL)-rich rafts that assemble in the Golgi complex and form vesicles that carry proteins towards the apical domain. This exclusion may be overcome by endowing the Na⫹-K⫹-ATPase with a sequence signal from the fourth transmembrane segment of the ␣-subunit of H⫹-K⫹-ATPase (TM4 signal) that suffices to readdress the Na⫹-K⫹-ATPase towards the apical domain. However, there are nongastric H⫹-K⫹-ATPases that, in spite of lacking the TM4 signal, are nevertheless addressed towards the apical domain. On the basis of their work with chimeras, Dunbar and Caplan (130) convincingly suggest that these differences in the polarized expression of ATPases can be explained as follows: 1) gastric H⫹-K⫹ATPase has the TM4 apical addressing signal already formed; 2) nongastric H⫹-K⫹-ATPases lack the TM4 signal, but would be able to form it through a particular arrangement of the molecule that would join two separated segments and thereby complete the signal sequence; 3) also Na⫹-K⫹-ATPase lacks a TM4 but, at variance with nongastric H⫹-K⫹-ATPases, it is unable to form one by reconfigurating the ␣-subunit in space; only the insertion of a TM4 signal by molecular engineering achieves its apical expression (130, 131). Based on studies of cultured MDCK cells, three models have been proposed for the development and polarized expression of Na⫹-K⫹-ATPase. One of these models involves intracellular sorting of newly synthesized proteins at the Golgi apparatus, followed by a vectorial delivery of the Na⫹-K⫹-ATPase molecules to a distinct surface domain (54, 378, 499). An alternative model emphasizes random delivery of newly synthesized Na⫹K⫹-ATPase molecules to the entire plasma membrane, but selective retention of this protein at specific sites of the plasma membrane by attachment to the submembrane cytoskeleton (206). A third posibility discussed below attributes an important role to the ␤-subunit. 1. Role of the cytoskeleton The activity and polarized distribution of renal Na⫹K -ATPase appears to depend on a connection of ankyrin to the spectrin-based membrane cytoskeleton, as well as on association with actin filaments. Na⫹-K⫹-ATPase not only copurifies with ankyrin, spectrin, and actin but also with three further peripheral membrane proteins: pasin 1 and pasin 2 (258) and moesin (259). A specific binding site for ankyrin has been localized on the ␣-subunit (120). Interestingly, the Drosophila Na⫹-K⫹-ATPase ␣-subunit conserves an ankyrin binding site (498) and codistributes with ankyrin and spectrin in polarized fly cells (26, 27, 128, 129). However, its polarized distribution was not altered in spectrin-null mutants (274, 275). Furthermore, Dubreuil et al. (129) using mutations in the Drosophila ⫹

Physiol Rev • VOL

␤-spectrin gene provided the first direct evidence that ␤-spectrin determines the subcellular distribution of the Na⫹-K⫹-ATPase and that this role is independent of ␣-spectrin. Unlike most epithelia, the retinal pigment epithelium (RPE) distributes the Na⫹-K⫹-ATPase to the apical membrane (44, 51, 204, 422). Early studies on rat RPE monolayers (204) suggested that an entire membrane-cytoskeleton complex is assembled with opposite polarity. Recent studies have shown that other polarized membrane proteins such as viral envelope membrane proteins do preserve their polarity in RPE cells (43, 44). Furthermore, Rizzolo and Zhou (377) used the RPE of chicken embryos and observed that the Na⫹-K⫹-ATPase and ␣-spectrin segregate into different regions of the cell. Despite its segregation from ␣-spectrin, the Na⫹-K⫹-ATPase appears to associate with a macromolecular complex in microvilli, suggesting that these properties prevent the Na⫹-K⫹ATPase from complexing with the ␣-spectrin-based cytoskeleton by sequestering the enzyme into the compartment where its activity is required. Discussion of the polarized distribution of Na⫹-K⫹-ATPase will be pursued below. IV. TIGHT JUNCTIONS Epithelia separate biological compartments with different composition, a fundamental role that depends on the establishment of occluding junctions. It is generally assumed that while TJs play this role in vertebrates, septate junctions (SJs) play it in invertebrates. Yet, as discussed below, SJs are transiently present in certain organs of vertebrates during development and permanently expressed in their nervous system. TJs were so belittled that more than a century after they were first described, they were not even represented in the model of Koefoed-Johnsen and Ussing (252). The fact that preparations of “tight epithelia”, with a transepithelial electrical resistance (TER) in the order of thousands of ohms per square centimeter, gradually decrease this parameter after several hours of being mounted between two chambers, led one to assume that epithelia like the intestinal mucosa or the gall bladder, whose TER only amounts to ⬍100 ⍀ · cm2 from the outset, did not withstand either dissection or harsh in vitro conditions, yet the observation that despite their low TER, these epithelia did transport substances vigorously (see, for instance, Refs. 47, 121, 122, 123, 373, 374) and many physiologically important substances flow mainly through a paracellular route limited by the TJ, led to a reassessment of the biological role of the thereafter called “leaky epithelia.” But even then, given its poor ability to discriminate between diverse permeating species, compared with the plasma membrane, it was expected that the TJ would

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

1237

FIG. 3. Effect of ouabain on nucleus and adhesion complexes (NACos). The diverse types of cell junctions have specific molecular components that, whenever the degree of attachment with the neighboring cell is weakened below a certain grip, abandon the scaffold and travel to the nucleus where they switch on or off genes that have to do with proliferation, differentiation, etc. A: essential components of cell-cell junctions. The membrane-attaching molecule is represented in pale purple, and highly glycosylated (green). Proteins that shuttle from cell junctions to the nucleus (NACos) are represented in yellow. Cytoskeletal linkers are in pink and other signaling proteins are in blue. B: monolayer of MDCK cells under control condition, showing the distribution of ␤-catenin (green) mainly on the lateral borders. C: in monolayers treated with ouabain, ␤-catenin (green) shuttles to the nucleus (blue). D: same monolayer as in B, showing the typical distribution of ZO-1 (red). E: ouabain does not provoke shuttling of ZO-1 toward the nucleus. ZO-1 and ␤-catenin in ouabain-treated monolayers are endocytosed, and the chicken fence pattern starts to segment. B and D (as well as C and E) correspond to the same area and same optical slice taken at the middle of the nucleus. (From C. Flores-Maldonado and I. Larre, unpublished results.)

consist of a couple of rather inconspicuous molecules placed in neighboring cells and bridged by a mere Ca2⫹ salt link (57). The scope has since drastically changed, due to a series of observations: 1) TER ranges from 10 (e.g., proximal kidney tubule) to ⬎10,000 ⍀ · cm2 (e.g., urinary bladder), indicating that TJs can adjust the degree of tightness to physiological needs (91, 92). 2) The TJ has been found to consist of a cluster of protein species (ZO-1, ZO-2, ZO-3, cingulin, occludin, claudins, etc.; see Fig. 3A and Table 1) that stretches from its membrane lips to the cytoskeleton (425, 451). 3) Some of these proteins contain nuclear addressing and nuclear export signals (76, 187, 224). 4) TJ molecules change their degree of phosphorylation in response to physiological conditions and pharmacological challenge (21, 86). 5) In a given moment, TJs may relax their tightness to allow the passage of macrophages toward an infected site, or spermatozoa in their travel from the Sertoli cell to the lumen of the seminiferous tube (49, 81, 351). 6) There is an increasing number of autoimmune diseases associated with faulty TJs that allow the passage of peptides from the intestinal flora. The immune system develops antibodies Physiol Rev • VOL

that not only attack the microbial antigen, but neurons, ␤-cells from the pancreas, the thyroid gland, and other targets of the host, whose proteins have sufficient homology with the intruder molecule (58). 7) Some TJ-associated molecules contain consensual segments with tumor suppressor proteins (182, 483, 488). 8) TJs act as a barrier that prevents lipids in the apical and the basolateral membrane from mixing (126, 127, 460, 461). 9) Lipids are themselves part of the structure of the TJ (50, 334). Physiologists have traditionally described cell functions such as the action potential, exchange diffusion, and cotransport decades before the specific molecules that performed these roles could be found. The picture is now totally reversed, as we know of dozens of proteins (e.g., the ones mentioned in the section above) whose function is mostly unknown. Some mutations in claudin genes severely impair the TJs (e.g., deletion of claudin-16/paracellin suppresses the ability of kidney nephrons to reabsorb Mg2⫹ and Ca2⫹) (414), and mutations that result in the absence of claudin 14 are responsible for autosomal recessive deafness (39, 474). Knockouts of claudins 1, 5, and 11 produce severe damage of the epidermal, bloodbrain, and myelin barriers, causing dehydration in the

84 • OCTOBER 2004 •

www.prv.org

1238 TABLE

CEREIJIDO, CONTRERAS, AND SHOSHANI

1.

Functional classification of molecules in the different types of cell junctions

Junction

Transmembrane Protein

Adherens

Nectin E-cadherin

Tight

Claudins JAMs Occludin

Desmosomes

Desmoglein Desmocollin ␣-Integrin ␤-Integrin

Focal

NACos

Signaling Proteins

ARVCF ␤-Catenin ␣-Catenin AJUBA ZONAB CDK4 Symplekin huASH1 ZO-2

SRC family

Plakoglobin

PKC

Paxilin Calreticulin FHL-2 Hic-5 PINCH CDK6 Zyxin

SRC family ILK FAK

PKA Heterotrimeric G proteins PKC Rho-family GTPases

Cytoplasmic Plaque Proteins*

AF6/AFADIN Vinculin ␤-Catenin ␣-Catenin Cingulin (ZO-2, ZO-3, AF-6, and JAM) PAR-3 (JAMs, PAR-6, atypical PKC) PAR-6 (PAR-3) PATJ (Pals-1, ZO-3, claudin) PALS-1 (CRB1, PATJ) ZO-1, 2, 3 (occludin, claudin) Desmoplakin

␣-Actinin Vinculin Talin Filamin

Transmembrane proteins are those that interact with homotypic or heterotypic proteins of adjacent cell or extracellular matrix. NACos are proteins that can localize to the nucleus and adhesion complexes. * Some of the specific proteins that interact with the plaque molecules are listed in parentheses. ARVCF, armadillo repeat gene deleted in VCFS (Velo-cardio-facial syndrome) thought to contribute to the morphoregulatory function of the cadherin-catenin complex (294); NECTIN, a Ca2⫹-independent immunoglobulin-like cell-cell adhesion molecule at AJs associated with E-cadherin through their respective peripheral membrane proteins, afadin, and catenins (432); AF7/AFADIN, a peripheral membrane protein that connects nectin to the actin cytoskeleton (432); AJUBA, a cytosolic protein found at sites of cell adhesion and a member of the zyxin family of LIM proteins (293); CRB1, a human ortholog of Drosophila Crumbs, a transmembrane protein that plays an important role in epithelial cell polarity (384); zyxin and paxillin, the prototypes of two related subfamilies of LIM domain proteins that are localized primarily at focal adhesion plaques (468); CDK4 and CDK6, cyclin-dependent kinases that function as nuclear regulators of the cell cycle (19); PINCH, a five LIM domain and an integrin-link kinase (ILK) binding protein involved in the regulation of integrin-mediated cell adhesion (463); Hic-5, a paxillin-related focal contact protein that upregulates transcription of c-fos gene and is a coactivator of steroid receptor-activated transcription (494); calreticulin, ␣-integrininteracting protein with nuclear function, originally identified as a chaperone in the endoplasmic reticulum (116); FHL-2, an integrin-interacting LIM-domain protein which modulates the transcriptional activity of nuclear ␤-catenin (473); FAK, focal adhesion kinase triggers signaling cascades important for the regulation of cell proliferation and survival (216); filamin and talin, actin binding proteins which form mechanical links to the cytoskeleton and are involved in the organization of actin networks (493); plakoglobin, known also as ␥-catenin is a major component of the submembrane plaque of desmosomes where it binds to desmoglein; like its close homolog ␤-catenin, it can bind also to E-cadherin and can interact with LEF/TCF transcription factors (278); desmoplakin, a member of the plakin family at desmosomes that connects cytoskeletal elements to each other and to the junctional complex, plays a crucial role in orchestrating cellular development and maintaining tissue integrity (278).

mouse (161), selective alteration of transport of molecules of 800 Da or less in endothelia (329), and slow nerve conduction (191, 319), respectively. It can be argued that, although there is ample evidence that TJs restrict diffusion through the paracellular permeation route, they might act as our lips, which enable our mouth to hold water, yet are not sewn together. Data supporting its role as an anchoring structure are somewhat scarce. The possibility exists that homologous interactions between transmembrane proteins located in neighboring cells (e.g., claudin/claudin) would stabilize them in this position but might not constitute a strength element holding cells together. A. Structure Proteins of the TJ have been divided according to several criteria, depending on whether they cross the membrane and pop up on the extracellular side, associate specifically with the cytoplasmic side of the TJ, have PDZ Physiol Rev • VOL

segments that bind them to other protein species forming stable scaffolds, anchor this structure to the cytoskeleton, belong to the TJ only transiently, for instance, during junction assembly and sealing, or because they are proteins like the NACos (see sect. IVF) that shuttle between the TJ and the nucleus where they act as transcription factors (20, 63, 76, 182, 301, 451). B. Transmembrane Proteins Occludin and claudins belong to the tetraspanin superfamily (256), which has four membrane-spanning domains, two extracellular loops, and the NH2 and COOH termini in the cytoplasm (159, 162). The extracellular loops of occludin are characteristically rich in glycine and tyrosine residues (300). The COOH-terminal domain binds a number of TJ plaque proteins including ZO-1 (142, 163, 226), ZO-2 (225, 477), ZO-3 (208), and cingulin (105). The NH2-terminal and the first extracellular domain modulate transepithelial migration of neutrophils (110, 219). Occlu-

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

din contributes to the structure and sealing of the TJ (158, 265, 304, 309, 458, 480). Although the roles of occludins in TJ assembly and functions are clearly demonstrated, null mutant mice expressed well-developed TJs (391–393). Claudins are the major transmembrane proteins of tight junctions (159, 164). The mammalian claudin family comprises 25 members (182, 218, 451) that are the main constituents of the characteristic strands of TJs observed in freeze-fracture replicas. Claudin by itself is able to form these strands and recruit endogenous ZO-1 when expressed in fibroblasts (164, 319, 320). The COOH terminus is intracellular and has a domain that binds the PDZ proteins ZO-1, ZO-2, ZO-3 (225), PATJ (383), and MUPP-1 (205) (see below). Different claudins copolymerize along the same TJ strand and bind certain types of claudins of the neighboring cell (165). The type of claudin expressed is responsible for some specific functions of the TJ in a very strict spatial-temporal fashion (93, 94, 255, 457). Thus epithelial cells of the proximal tubule and MDCK have a characteristic low TER phenotype due to the expression of claudin-2 (160, 250, 375). Junction adhesion molecule (JAM) is a protein of epithelial and endothelial cells with a single transmembrane domain. This protein is important for neutrophil migration through the endothelial cell layer (295). Its intracellular domain binds AF-6 (132), ASIP/Par 3 (133, 227), ZO-1 (28, 132), and cingulin (28). C. Membrane-Associated Proteins The cytoplasmic domain of TJ membrane proteins binds to a complex cluster of intracellular proteins like ZO-1, ZO-2, ZO-3, and Pals, which belong to the membrane-associated guanylate kinase homolog family (MAGUK) (141, 187, 239, 384, 483). Stevenson et al. (425) identified the first known TJ protein, ZO-1 (zonula occludens) (see also Ref. 5), that is a prominent associated peptide, judging from the number of associations and changes in phosphorylation it goes through. ZO proteins contain a series of domains, such as PDZ, which enable these peptides to interact with other ZO, occludins, claudins, and with the actin cytoskeleton (141–143, 226, 477, 478). MAGI (MAGUK inverted protein) colocalizes with ZO-1 (124). MAGI-1b localizes to the basolateral membrane and forms complexes with ␤-catenin and E-cadherin during junction formation (222) and in pallidoluysian atrophy (191). Notice that although ␤-catenin and E-cadherin are the key components of adherens junctions, they influence the TJ (see below). Tumorigenic proteins of adenovirus and papilomavirus target for degradation, or sequester MAGI-1 (179). MAGI-1 appears to be a tumor suppressor (179) that interacts at the TJ with the signaling molecule GEF, a guanine nucleotide exchange factor participating in the Rho signaling pathway (313). MAGI-2 and -3 interact with PTEN, an inositol trisphosphate phosphatase Physiol Rev • VOL

1239

(488, 489), and MAGI-2 binds megalin (multi-protein receptor mediating endocytosis in kidney proximal tubules; Ref. 345). PARs are partitioning-defective proteins involved in embryonic polarity. PAR-3 localizes at the TJ through association to the COOH terminus of JAM (227) and forms a complex with PAR-6, a single PDZ-possessing molecule with a CRIB domain (232), and atypical PKCs ␭ and ␨ (PAR-3/ ASIP, atypical PKC isotype-specific interacting protein) (228). Par-6 inhibits TJ reassembly after junctional disruption induced by Ca2⫹ depletion (169). MUPP1 (multi-PDZ domain protein 1) functions as a cross-linker between claudin-based TJ strands and JAM oligomers in TJs (205) and retains MAGUK protein Pals1 through its MAGUK recruitment domain (MRE) (384). AF-6 is transiently expressed at tight (491) and adherens junctions (292), suggesting a role in the formation of junctions (182). It is also an ALL-1 fusion partner at chromosome 6 associated with acute leukemia (363). PATJ is another junction-associated protein, which contains 10 PDZ domains that bind it to ZO-3 and that can also be found at the apical plasma membrane (383, 384). Cingulin is a molecule with globular domains and a central ␣-helical rod region necessary for dimerization (88). Through several domains spread along the molecule, specially the ZIM (ZO-1 interacting motif), cingulin cross-links with ZO-2, ZO-3, AF-6, and JAM to the F-actin and myosin cytoskeleton (28, 105, 106, 114, 115). ZONAB is a transcription factor that regulates ErbB-2 and paracellular permeability (19, 22). Other TJassociated proteins are symplekin, which is related to the polyadenylation of mRNA (431), the transcription factors HuASH1 and AP-1 (40, 325), MAGI-3, an atypical PKC (13, 179, 228, 427), JEAP, which appears to anchor other TJassociated protein species (328), 7H6 (247), as well as Pilt (243). Another group of TJ-associated proteins is involved in vesicle traffic: Rab13 (298, 409, 497), Rab3b (426), and Sec6/8 complex (198). Finally, TJs also contain proteins associated with G proteins like Gi-0␣, Gi-2␣, G12␣, Gs␣ (119, 125, 389, 390). D. Lipids TJs appear on freeze-fracture replicas as continuous anastomosing strands. These strands are thought to be composed of either protein (420) or lipids (237, 358). The “protein model” depicts the strands as polymers of protein molecules in the plane of the plasma membrane that join, through their external domains, to the corresponding polymer of the neighboring cell. The preponderant participation of proteins is strongly supported by their content of transmembrane proteins such as occludin (162) and claudins (159). Transfected claudins even promote formation of strands resembling those of epithelial TJ in fibroblasts (164, 262). The “lipid model” in turn depicts the strands as cylindrical micelles with the polar groups of the lipids directed

84 • OCTOBER 2004 •

www.prv.org

1240

CEREIJIDO, CONTRERAS, AND SHOSHANI

toward the axis, and the hydrophobic tails immersed in the lipid matrix of the plasma membrane of both neighboring cells (237). It is in keeping with the fact that the lipid-soluble probe dipicrylamine can be transferred with the aid of an applied voltage from the cell membrane of a previously loaded cell to the membrane of a neighboring one (453). It is also supported by the recovery of large bleached areas with lipids diffusing through the TJ (192) and by the cytochemical localization of phospholipids with gold complexed phospholipase A2 (240). However, several studies have failed to support or discard this model (126, 127, 326, 401, 419, 460, 461). Lipidic messengers, like diacylglycerol, play a role in TJ formation (20, 21). Lipid phosphatase PTEN is also associated with the TJ and participates in tumor suppression (488, 489). The possibility exists that strands would not be made exclusively of proteins or lipids, or that lipids would participate indirectly as a source of a second messenger that may in turn regulate TJs. Recent evidence supports both possibilities. Thus changing the total composition of phospholipids, sphingolipids, cholesterol and the content of fatty acids does not alter either TER or the structure of the strands, but enrichment with linoleic acid increases the paracellular flux of dextran without detectable modifications of either TER or TJs (50). Cholesterol depletion elicited by treating MDCK cells with methyl ␤-cyclodextrin transiently increases TER (156, 287). MDCK I and Fisher rat thyroid cells spontaneously express high TER in normal culture conditions, yet when their synthesis of glycosphingolipid is inhibited with 1-phenyl-2-hexadecanoylamino-3-morphilino-1-propanol-HCL (PPMP), TER markedly decreases without a noticeable structural changes in the TJs (279). Another experimental evidence pointing to lipid involvement in the TJ is that hyperphosphorylated occludin and ZO-1 are found in lipidic rafts. These rafts are detergent-insoluble fractions, enriched with glycolipid, cholesterol, and proteins like caveolin-1. These TJ proteins coprecipitate and partially colocalize with caveolin-1 and are displaced from the “raftlike” compartment after TJ disassembly by calcium chelation (334). E. Diversity Arising From Processing TJ Proteins as Well as by the Expression of Several Isoforms ZO-1 has three splicing variables (17, 187). ZO-1-␣ⴙ has an 80-amino acid domain, called the ␣-motif, inserted in the COOH-terminal half (17, 476). This variant is associated with the development of TJs and is abundant in epithelia (17, 263, 455). ZO-␣ⴚ lacks the ␣-motif, is abundant in epithelia that express very dynamic TJs, like Sertoli cells, endothelia (17), and even in cells like podocytes that do not express TJs (263). Occludin is produced by a single gene (human chromosome band 5q13.1, Ref. 391) and is modified during Physiol Rev • VOL

posttranslation. Two alternative splicing isoforms are known: occludin 1B, a longer variant that has a 56-amino acids insertion in the NH2 terminus (324), and occludin T4M(⫺), a short variant that lacks the fourth transmembrane domain and causes the COOH terminal to be exposed to the extracellular space (177). The ZO-2 gene employs two alternative promoters that give rise to two ZO-2 isoforms differing at their amino-terminal portion by 23 amino acids. Although both isoforms are present in normal tissues, the longer one is absent in most pancreatic cancers (82– 84). F. Proteins That Can Localize to the Nucleus and Adhesion Complexes Some junction-associated proteins contain nuclear address and nuclear export signals (86, 187, 224) that enable them to shuttle back and forth between the TJs as well as from other types of adhesion complexes, to the nucleus (Table 1; Fig. 3). Upon arriving at the nucleus, proteins that localize to the nucleus and adhesion complexes (NACos) activate transcription, modify mRNA processing and trafficking, activate c-jun kinase, alter the G1/S phase transition of cell cycling, modulate histone methyltransferase, proliferation, cell density, oxidative stress, as well as interact with other molecules within the nucleus and submembrane scaffolds determine cell fate during embryonic development and are involved in tumorigenesis (23). In other words, the diverse cell junctions have specific molecular components that whenever the degree of attachment is weakened below a certain grip, they abandon the scaffold and travel to the nucleus where they switch on or off genes that have to do with proliferation. G. Phosphorylation in TJ Assembly and Function As mentioned above, both the assembly (20) and disassembly of the TJ (85) involve important phosphorylation steps. ZO-1 and ZO-2 become phosphorylated on Ser, Thr, and Tyr residues. Cingulin is phosphorylated on Ser residues, and occludin has several levels of phosphorylation on Ser and Thr that are required for its incorporation into the TJ (86, 394). Cingulin is phosphorylated in serine residues by a kinase insensitive to PKC activators or inhibitors (87). Likewise, the assembly of TJs depends on vinculin phosphorylation on Ser and Thr (352). ZO-1 in epithelia with low TER is more Ser-phosphorylated than in high-TER epithelia (424). Hypoxia in brain microvessels enhances phosphorylation, decreases expression, and delocalizes ZO-1 (149). However, low phosphorylation of ZO-1 has been detected in cells that lack TJs or have ZO-1 disassembled through calcium depletion (215).

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

Vascular endothelial growth factor increments Tyr phosphorylation and paracellular permeability (7). Epidermal growth factor induces Tyr phosphorylation of ZO-1 and relocalizes this protein towards the apical membrane of A431 cells (459), and tumor necrosis factor increases TJ permeability through Ser and Thr phosphorylation of occludin (89, 90). During TJ assembly ZO-1 is phosphorylated in tyrosine residues in a MAPK regulated fashion (79). Phorbol esters disassemble TJs and downregulate claudin-2. ZO-1 associates and is a substrate of ZAK, a Ser/Thr kinase (18) and of PKC (13). ZO-2 is Tyr phosphorylated when epithelial cells are transfected with v-src (433), phosphorylated in Ser and Thr residues by cAMPdependent protein kinase (PKA) and atypical PKC when TJs are either absent or disassembled by Ca2⫹ removal (13). Occludin phosphorylation in Ser and Thr residues is required to recruit occludin to the TJ (394), whereas phosphorylation in Tyr is involved in disassembly and opening of TJs (118). Although we still have no dynamic model to explain the interplay of Ca2⫹ levels, small GTP-binding proteins, phosphorylation, and TJ-associated molecules, there is ample evidence that this cascade involves the cytoskeleton that is linked to E-cadherin through p130, ␣-, ␤-, and ␥-catenins, vinculin, ␣-actinin, fodrin, and spectrin (496). In fact, actin also combines with ZO-1, ZO-2, and ZO-3, occludin, cingulin, and other TJ molecules. The cytoskeleton is likely to constitute a structural framework as well as an informative network conveying signals from the adherens junctions to the TJ and back. Drugs interfering with microfilaments and microtubules block junction formation (311, 312) and polarization during a Ca2⫹ switch, and reverse these processes in fully polarized cells with already established TJs (496).

1241

integrity, possibly by anchoring to the cytoskeleton (151, 153). Occludin and ZO-1␣⫹ are assembled in the last stage (32 cells) (408, 410). In mouse and human, the TJ mRNAs of claudin-1, JAM, occludin TM4⫹ and TM4, and ZO-1␣⫺ are initially inherited from maternal transcription and followed by embryonic transcription from the two-cell stage onward, and remain present throughout preimplantation development (154, 155, 176). Only ZO-1␣⫹, ZO-2, and desmocolin-2, a component of desmosomes, are transcribed later on from the embryonic genome, during 16- to 32-cell stage in human and mouse (176, 408). Development of TJs in Xenopus embryos is quite different from that of mouse, human, or bovine, due to the pressure imposed on Xenopus to develop rapidly swimming tadpoles, which are able to escape predators. The Xenopus egg has a very impermeable membrane, due to removal of transport proteins like the Na⫹-K⫹-ATPase through endocytosis (147, 151, 398). Xenopus embryos develop a polarized distribution of cadherins XB/U after the first cleavage, in the two-cell stage, coincidentally with the nascent blastocoele (6, 238). Sealed TJs develop at this stage, although in basal position and without constituting a fence for basolateral proteins (147, 310). TJs are initially assembled in the membrane at the animal pole, by the end of zygote cytokinesis. Cingulin is the first TJ protein to be incorporated, followed by ZO-1, then occludin. Interestingly, formation of the new apical membrane and the generation of cell polarity in Xenopus precede initiation of TJ formation, and TJ proteins assemble at the apical-basolateral boundary in the complete absence of intercellular contacts, indicating that the mechanism of TJ biogenesis relies on intrinsic autonomous cues (147). V. SEPTATE JUNCTIONS

H. Biogenesis Biogenesis of the TJs is closely related to development. In compactation, blastocyst formation, gastrulation, and neurulation, epithelia separate compartments of distinct composition. The formation of primordial epithelia results from maternal (e.g., in Xenopus) or embryonic (e.g., in mice) expression programs (151, 153). The first stage of TJs formation starts 1–2 h after compactation, with the assembly of plaque proteins ZO-1␣ⴚ and rab13 at the eight-cell stage (150, 409). This process depends on E-cadherin, protein synthesis, and assembly of microtubules. In a second stage, cingulin plaque protein is incorporated at the 16-cell stage and stabilized in a process dependent on E-cadherin-mediated adhesion (152, 230). E-cadherin seems to be necessary not only for spatial organization of the TJs, but also for maintaining their Physiol Rev • VOL

The first description of SJs in Hydra was made by Wood (482). While TJs are characteristic of chordates, nonchordates have instead SJs (269). SJs can be found in the blood-brain and blood-testis barriers of adult arthropods and even in the Ranvier nodes of vertebrates. Green and Bergquist (194) found that sponge junctions are difficult to locate due to their transient nature but have extremely regular intercellular spacing even in the absence of any septa. In cross-sectional views of the different types of SJ, there is little variation, as virtually all septa span a 15- to 18-nm intercellular space. Coelenterata have clear SJs. Mollusca and Arthropoda possess the well-known mollusk-arthropod pleated septate junctions (420). Tunicata do not have SJs, but rather a variation of the vertebrate TJ (175, 285). Some insects have TJs in the central nervous systems and rectal pads (266 –268, 271). Furthermore, Toshimori et al. (448) described a type of TJ

84 • OCTOBER 2004 •

www.prv.org

1242

CEREIJIDO, CONTRERAS, AND SHOSHANI

in the cyst envelope of the silkworm testis that does not form extensive anastomosing arrays. These structures might not be true TJs (48, 193, 331). However, Lane and Chandler (270) clearly demonstrated the existence of what appear to be true TJs in the central nervous system of arachnids. VI. ADHERENS JUNCTIONS A. Structure and Function The adherens junction is a large multiprotein cluster that plays crucial roles in tissue organization and patterning. It mediates homotypic cell-cell adhesion and the transduction of extracellular signals. E-cadherin, a classical Ca2⫹-dependent homophilic cell adhesion molecule (434), is characterized by five extracellular structural repeats (EC1 to EC5) and a highly conserved cytoplasmic domain that associates with several cytoplasmic proteins, most prominently the catenins (344), which associate in turn to actin cytoskeleton (203, 251, 470, 495). E-cadherin is a well-known polarity-inducing protein that is able to polarize Na⫹-K⫹-ATPase in fibroblasts (307). In polarized MDCK cells, E-cadherin is localized to the lateral membrane (34). Newly synthesized E-cadherin is preferentially sorted to the lateral membrane (273) and binds strongly to the ␤-catenin (212), a protein that is necessary for efficient delivery of the complex to the plasma membrane (80). Basolateral delivery of E-cadherin relays upon a double leucine motif present in the intracellular domain (314). Ca2⫹ interacts with the extracellular part of Ecadherin (100, 186), more specifically with a motif of three amino acids (364). Ca2⫹ binds to the junctions between extracellular repeats of E-cadherin, changing its conformation (333, 407), and allowing it to aggregate with other E-cadherin molecules on the same cell, an arrangement that favors binding to the E-cadherin of neighboring cells (495). When adherent junctions are blocked with specific antibodies against the extracellular domain of E-cadherin, TJs do not form and, if already established, they reopen (103, 199, 200, 201). When the amino acid triplet His-AlaVal (HAV) from the extracellular domain of E-cadherin is blocked with specific peptides containing an HAV sequence, the functions of the E-cadherin/catenin complex are interfered (330). However, HAV cannot act by itself, as flanking sequences are important in the binding selectivity of HAV peptides to E-cadherin (290, 372). Peptides from the bulge and groove regions of the EC1 domain of E-cadherin can inhibit cadherin-cadherin interactions, resulting in the opening of the cellular junctions (416). The initial contact is restricted to small regions called “puncta” (3, 462). Vasioukhin et al. (462) demonstrated that Ca2⫹ stimulates the formation of very dynamic filopodia that penetrate and embed into neighboring cells. Physiol Rev • VOL

The initial AJ is extended in a process similar to a “zipper” closure. This chain of reactions is interrupted by the failure in ␣-catenin (470) and ␤-catenin, a critical component of the Wnt signaling cascade (305, 349). When wnt extracellular signals instruct cells to proliferate, dephosphorylated ␤-catenin is targeted to the nucleus and associates with the transcription factor LEF/TCF (37). In nonproliferating cells, phosphorylated ␤-catenin is removed from cell contacts and, once in the cytoplasmic pool, is bound to the axin and adenomatous polyposis coli protein complex (APC), where it is ubiquitinated and targeted to the proteasome for degradation (1, 190). Hence, the regulation of adhesion seems to be exerted, at least in part, by the titration of ␤-catenin from the cell contacts by APC. APC also binds to microtubules and participates in the formation of parallel tubulin bundles (316) involved in asymmetric cell division (353, 492). Epithelial to mesenchymal transition (EMT) is the loss of cell-cell interactions and acquisition of a migrating phenotype of cells that changes the adhesive epithelial phenotype to a fibroblastic-like migrating one (35, 36, 38, 423). It requires loosening of the E-cadherin/catenin-dependent strong cell-cell adhesion of epithelial tissues (202, 220, 435), as well as silencing the expression of E-cadherin and TJs proteins (53, 223). Cano et al. (53) and Pe´ rez-Moreno et al. (354) have identified the E-cadherin transcriptional repressors Snail and the mouse E12/E47 that are members of the zinc finger family and product of the E2A gene, respectively. Both interact with the Ecadherin palindromic element E-pal, present in E-cadherin promoter, and silence its expression. In addition to its effect on the E-cadherin, Snail binds directly to the E-boxes of the promoters of the claudin/occludin genes, resulting in complete repression of their promoter activity (223). In epithelial cells EMT can be triggered by the binding of the hepatocyte growth factor/scattering factor (HGF/SF) to its receptor, c-met, through the activation of the ras and MAPK signaling pathway (350). HGF/SF induces the ubiquitination of E-cadherin by Hakai, which is a member of the ubiquitination machinery, that induces endocytosis and dynamic recycling or degradation of Ecadherin, and the subsequent perturbation of cell-cell adhesions (157). B. Relationships between Adherens and Occluding Junctions Both types of junctions maintain a fundamental, but a highly complex relationship. TJs depend on the E-cadherin/E-cadherin interaction throughout the life of the epithelium, as TJs in mature monolayers can be opened by interfering with E-cadherin. E-cadherin does not localize in the TJ but triggers the cascade of chemical events

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

resulting in TJ formation from afar (20). Nevertheless, Troxell et al. (450) found typical junctional strands and some TJs markers, such as ZO-1 and occludin, in cells whose expression of endogenous E-cadherin had been severely reduced. It is likely that E-cadherin would be also needed to hold the two neighboring cells together, so TJs can be formed. Heterotypic TJs can be established between cells from different organs of the same animal, and even from different animal species (185). This is illustrated in Figure 4, where a monolayer of cocultured MDCK (dog, unstained) and LLC-PK1 cells (pig, red) that exhibits homophilic (MDCK/MDCK and LLC-PK1/LLCPK1) as well as heterophilic TJs (MDCK/LLC-PK1) revealed by the continuous distribution of occludin and ZO-1 molecules (green), and by the development of a TER (not shown). E-cadherin instead is only observed at homologous MDCK/MDCK borders, as indicated by DECMA-1 antibody, a result that agrees with the observation that the cell-cell contact provided by E-cadherin is a highly specific one (495). The antibody used has no specificity for E-cadherin in LLC-PK1 cells but binds to Ecadherin of MDCK cells in homotypic borders. Taken together, these results indicate that E-cadherin triggers and supports TJs at the junction between different types of epithelia cells, like the ones commonly occurring in the nephron and the gastrointestinal tract (103). The life of higher organisms would be impossible without epithelial barriers that separate the internal from the environmental milieu. Therefore, it is conceivable that the most fundamental and evolutionary conserved role of the TJs is to act as a diffusion barrier and that finer regulation of TJ permeability, as well as their participation in the variety of functions mentioned in section I, would constitute a later development (for a recent review, see Refs. 23, 301). In this respect, it is interesting that Furuse et al. (165) deleted the COOH-terminal cytoplasmic domain of claudins and observed that these lose their ability to associate with ZO-1, ZO-2, and ZO-3. Nevertheless, these TJs still exhibit the characteristic meshwork of fibrils in freeze-fracture replicas.

1243

VII. POLARITY The life of a cell depends on thousands of different chemical reactions controlled by a myriad of enzyme species. Life would be impossible if these molecules had access to each other. Whenever a tissue is homogenized, temperature should be lowered below 4°C, and an abundant batteries of inhibitors should be added beforehand. Furthermore, each protein species should be targeted from the site of synthesis to the place in which it works (the Golgi apparatus, the cytoskeleton, peroxisomes, etc.), and degraded if found out of place (for a recent review, see Ref. 59). Therefore, all proteins should be assigned a specific place in the cell. In a wide sense, polarity is the consequence of targeting and selectively retaining different protein species to different sides of the cell, but the term is often restricted to the asymmetric expression of cellular features, such as microvilli, flagella, receptors, ion channels, pumps, and co- and countertransporters on a given pole of the cell, that constitute the structural basis of the asymmetric behavior of epithelia referred to in section I. Until a couple of decades ago, it was taken for granted that polarity was a peculiar property of epithelial cells and neurons. Today it is the other way around: all cells from single ones like bacteria, yeast, and spermatozoa to hepatocytes and osteoblasts have some degree of polarization. Were it not for membrane targeting and polarity, the monomers of a receptor synthesized and sent at random to the plasma membrane would have to ramble and diffuse on the plane until they meet by chance the other partners. Polarity may therefore reveal a principle of economy that speeds up the assembly of membrane structures. The fact that polarity is so old and widely distributed is reflected in the constancy of its fundamental mechanisms and by the fact that molecules and mechanisms underlying polarity, such as E-cadherin and vinculin or genes such as PAR 3 and PAR 6, can be found to play similar roles from yeasts to Caenorhabditis, Drosophila, and humans (for recent reviews, see Refs. 59, 479). However, it is important to stress that there was a

FIG. 4. The tight junction is a promiscuous structure, yet it depends on adherens junctions which are not. Epifluorescence image of a monolayer formed by a mixed population of MDCK and LLC-PK1 cells. LLCPK1 cells were labeled beforehand with 6.3 ␮M CMTMR.

Physiol Rev • VOL

84 • OCTOBER 2004 •

www.prv.org

1244

CEREIJIDO, CONTRERAS, AND SHOSHANI

very long evolution before polarity became triggered by contact clues and, besides of serving the own necessities of the cell, started to participate in the assembly of multicellular organisms (472).

C. Naⴙ-Kⴙ-ATPase, Cell Attachment, and the Position of the TJ

A. The Transporting Epithelial Phenotype The model put forward by Koefoed-Johnsen and Ussing (252, 456) had three basic asymmetries: 1) only the outward-facing membrane (apical) has a specific permeability to Na⫹; 2) only the inner facing membrane (basolateral) has a K⫹ specific permeability; and 3) Na⫹-K⫹ATPase is asymmetrically situated on the inner facing membrane of the cell. In the following four decades the model of Koefoed-Johnsen and Ussing has been amply confirmed and complemented with important new findings summarized below. B. Polarity and the TJ Clear-cut demonstrations that TJs are not responsible for the polarized distribution of membrane proteins stem from the study of receptors for immunoglobins, ferritin, and cholesterol-binding-protein and from the observations already mentioned above that upon switching confluent MDCK cells to Ca2⫹, TJs form so rapidly that a fraction of Na⫹-K⫹-ATPase is trapped in the apical (wrong) side, but is thereafter removed and the cell attains the normal polarization of this enzyme in the next couple of hours (96). However, as discussed below, TJs may be in fact responsible for the polarized transport of fluid. A TJ itself is polarized, as some of its molecules are targeted very precisely to and from the TJ to other places such as the basolateral membrane (165, 224, 299, 394). Actually, the experimental dissection between TJs and polarity is hard to achieve, as interference with evolutionarily conserved signaling cascades starting at membrane contacts affect both TJs and polarity. Proteins, such as PAR3, PAR4, and PAR6, identified originally in the nematode Caenorhabditis elegans (246) have homologs in Drosophila and mammals (281, 337, 427, 443, 444). Furthermore, Baas et al. (16) have recently identified a human homolog of PAR4, called LKB1, whose activation triggers the development of the whole transporting epithelial phenotype even in single, noncontacting cells. ZO-1 is a member of the same protein family as Drosophila Discs-large tumor suppressor (452, 476). The situation is in fact much more complex, because different TJ-associated signal-transduction systems might influence each other (for a recent review, see Ref. 301). Nevertheless, the TJ is important to preserve the polarization of mobile membrane molecules such as lipids (126). But even this role does not seem to be that of a Physiol Rev • VOL

simple fence. Thus transfection of occludin with its COOH terminus truncated impairs the ability of the TJ to retain a fluorescent lipid probe in the apical domain (24).

The complex mechanisms described above are the product of a long evolution and might not have been present in primeval metazoans of pre-Cambrian times, more than 600 millions years ago. The first metazoans exchanging through epithelia must have had much simpler mechanisms. One of the simplest occurring in an epithelium would be a membrane molecule with the capacity to attach to a similar one in the neighboring cell, so the pair would get stuck at the contacting border (Fig. 5). The Na⫹-K⫹-ATPase might constitute a case in point. Axelsen and Palmgren (15) propose that the third subunit of bacterial K⫹-ATPase (KdpC) may be the ancestor of the X-K-ATPase ␤-subunit, due to the similar assembly functions they both perform. As discussed above, in higher species the ␤-subunit is tightly and specifically bound to the ␣-subunit (42), and the association begins as soon as they are synthesized in the endoplasmic reticulum (55) so that both reach the plasma membrane forming already a hard-to-dissociate dimer, in which ␤ helps ␣ to trap K⫹ in a pocket during the pumping cycle (464). However, it is not expected that they be firmly bound in early organisms Caenorhabditis elegans because sequence analyses show no association domains (338). Therefore, it is conceivable that the ␣-subunit became a stable resident of the lateral space of transporting epithelia by virtue of being bound to a ␤-subunit, which in turn has the ability to dwell in this position because of a linkage it makes with another ␤-subunit placed in the plasma membrane of a neighboring cell (Fig. 5). However, a Na⫹-K⫹-ATPase located in a primitive epithelium as depicted in Figure 5 would be inefficient, as roughly one-half of the pumping fluid would leak back to the outer environment. Combinations of Na⫹-K⫹-ATPase at the cell-cell border with TJs would probably select epithelia in which TJs would be pushed toward the outermost end of the intercellular space, because it would ensure a maximal yield of fluid transported vectorially towards the inside (Fig. 5). VIII. EVOLUTION OF THE EPITHELIAL VECTORIALLY TRANSPORTING PHENOTYPE Evidence that mollusks can absorb ions from dilute media was already presented by August Krogh (261) (see Ref. 122). Water, ions, lipids, amino acids, and sugars were found to be transported by similar mechanisms in

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

1245

FIG. 5. Evolution of transepithelial transport. Hypothetical molecular (A) and cellular (B) events that may have intervened in the generation of a primeval transporting epithelium. Each yellow block represents an epithelial cell, single in A and paired in B. A: the ␣-subunit of Na⫹-K⫹-ATPase is represented as a membrane protein with several transmembrane domains (yellow), and the ␤-subunit has the characteristics of a cell-attaching molecule: a short cytoplasmic domain (blue), a single transmembrane domain (light blue), and a long extracellular fragment (purple). Both subunits associate (top row, middle) and are sorted to the plasma membrane (top row, right). B, left: the complex of ␣- plus ␤-subunits becomes stabilized at the lateral border of the cell, because it is the only position in the plasma membrane where the ␤-subunits of the two neighboring cell can interact. Middle: Na⫹-K⫹-ATPases pump ions into the intercellular space, the osmolarity of the ions attract an amount of water, and the fluid pushes intercellular material (gray) towards the outermost end of the intercellular space (TJ). In principle, the pressure exerted by the fluid may push the attaching material towards both ends of the intercellular space. However, those that push it towards the outermost end would be favored by selection, because in this configuration the intercellular space is open towards the inner side of the body and allows a net absorption of nutrients. Cell at the bottom right shows a hypothetical later step, in which the incorporation of co- and countertransporters into a given pole of the cell completes the machinery for the vectorial movement of substances across the epithelium. To avoid crowding, E-cadherin, whose paramount role is discussed in the text, is not represented in this drawing.

the intestine in Ascaris, earthworms, freshwater clams, insects, as well as in the mammalian intestine (4, 107, 221, 235, 365). Evolutionists refer to homology when two organs have the same role and evolutionary origin, but reserve analogy (an anatomical term) and homoplasy (its molecular counterpart) for organs that, in spite of playing the same physiological role, result from different phylogenetic processes. Classical examples are the wings of the butterfly and those of the bat. In this respect, the relationship between different occluding junctions is still debatable. Thus they play the role of occluding junctions (148, 308, 420) and share considerable homology between some of their molecules, such as claudins, ZO-1, and dlg (12, 485). Nevertheless, these types of junctions do show considerable differences in composition as well as in their evolution (301, 444). The next step in evolution is constituted by Cnidaria, whose most conspicuous representative is the hydra, a freshwater coelenterate first described by Abraham Tembley in 1744 (as cited by Gierer and Meinhardt, Ref. Physiol Rev • VOL

178). It reproduces through stem cells, and although its cells are not known to have apical/basolateral polarity, the organism does show regional differentiation, attributed to gradients of substances secreted by some of its cells (178). Fei et al. (144) have found that Hydra vulgaris has a homolog of ZO-1, termed HZO-1, that is a MAGUK protein, a family with members such as ZO-2, dlg-A, and TamA, which are involved in a wide variety of cellular functions such as TJ formation, cell proliferation, differentiation, and synapse formation. A. Evolution of the Naⴙ-Kⴙ-ATPase Thanks to the increasing number of organisms whose whole genome has been sequenced, Okamura et al. (338) could correlate the molecular evolution of the 11 subfamilies of the P-type ATPases within the establishment of the kingdoms of living things. Interestingly, heavy metal transporters (type 1B) and intracellular Ca2⫹-ATPases (type 2A) are probably the most fundamental for life,

84 • OCTOBER 2004 •

www.prv.org

1246

CEREIJIDO, CONTRERAS, AND SHOSHANI

since these two types are found in every kingdom. They appeared very early in evolution and played critical roles in ion homeostasis. On the other hand, the ancestors of animals probably found the Na⫹-K⫹-ATPase and H⫹-K⫹ATPase (type 2C) and got rid of the proton pump (type 3A) occurring in the lineage of plants and fungi. While the divergence of substrate specificity (ion selectivity) occurred early in the evolution of P-type ATPases and has been conserved ever since (15), the divergence of the P-type ATPase isoforms occurred after vertebrates and invertebrates separated (436). Recently, the study of evolution of P-type ATPases has been amplified with new information from the database for the nematode Caenorhabditis elegans and the fly Drosophila melanogaster. Focusing on key domains of both ␣- and ␤-subunits, such as the ouabain binding site and the ␣/␤-assembly site, a set of novel isoforms that retain an ancestral characteristic of the Na⫹-K⫹- and H⫹-K⫹-ATPase have been identified (338, 339, 437). In the phylogenetic analysis, the ␤-subunits of C. elegans and D. melanogaster form a unique single cluster. Interestingly, D. melanogaster possesses two distinct types of ␤-subunits, one type closer to the vertebrate ␤-subunits and the other sharing more homology with the C. elegans ␤-subunits. As mentioned before, the functional expression of the Na⫹-K⫹-ATPase requires the assembly of the ␣- and ␤-subunits. In this regard, the newly identified invertebrate subunit isoforms (Ce2C3 and Ce2C4 and Dm␤4 – 6) are of particular interest because they lack the characteristic domains that have been demonstrated to be critical for ␣/␤-assembly (140, 277, 467). Therefore, Takeyasu et al. (437) and Okamura et al. (338, 339) suggested that these nonassembling subunits may exist as lonely subunits and may play not-yetidentified function(s) other than in ATP-driven ion transport. Taken together, their studies suggest that the P-type ancestor first lacked the inhibitor binding site and the assembly domain, and therefore existed as a single subunit in lower invertebrate organisms. In its evolution, this ancestral form acquired the abilities to bind ouabain and to assemble with ␤-subunit, becoming the immediate ancestor of the currently known Na⫹-K⫹- and H⫹-K⫹ATPase family. Although the information on the molecular evolution of the ␤-subunit is comparatively scarce, it has been suggested that it derives from the third subunit of bacterial K⫹-ATPase (KdpC). Alternatively, the ␤m protein of sarcoplasmic reticulum could also represent a primitive form of the ␤-subunit family of the X⫹-K⫹-ATPases. B. Evolution of Junction Proteins When Dictyostelium cells run out of nutrients, they polarize and adhere to form a multicellular structure that supports the spore head (260). During this process, the cells at the top of the stalk tube form a constriction with Physiol Rev • VOL

rings of cells that express AJs with the ␤-catenin analogous aardvark associated to the actin cytoskeleton. Aardvark is also independently required for cell signaling (197) and shares significant homology with Saccharomyces cereviseae protein Vac8, Saccharomyces pombe SPBC354, and plant Arabidopsis thaliana AB016888 sequences. This demonstrates that in spite of lacking stable junctions, protozoa appear to have molecules that coordinate cytoskeletal dynamics, the position of the mitotic spindle and cell polarity, and that may have been precursors of molecules that make AJs and TJs in metazoans (197, 353). ␤-Catenin that, as discussed above, has a dual role in cell-cell adhesion and cell signaling, is present in the nonmetazoan amoeba Dictyostelium discoideum, indicating that it evolved before the origins of metazoan (197). It seems plausible that ␤-catenin may have been a requisite for all multicellular development (197). In this sense, Dictyostelium has ␤-catenin that plays signaling and adhesion roles as in vertebrate. C. elegans instead diverged, because it has two catenins: HMP-2 for adhesion and Bar-1 for signaling to the nucleus (257). Apical junctions in Caenorhabditis elegans have tetraspan VAB-9, which is a claudin-like membrane protein, that colocalizes with E-cadherin (HMR-1), and this localization depends on HMR-1, ␣-catenin (HMP-1), and ␤-catenin (HMP-2) (415). Hua et al. (218) analyzed the phylogenetic trees of connexins, claudins, and occludins and found no sequence or motif similarity between the different families studied, indicating that, if they did evolve from a common ancestral gene, they have diverged considerably to fulfill separate and novel functions. It has been recently demonstrated that Sinuous, a homolog of claudin in Drosophila, not only localizes to the septate junctions, but also confers to this structure its barrier function (33, 487). Kollmar et al. (256) only find a single claudin gene in the urochordate Halocynthia roretzi and concluded that claudins emerged when TJs replaced septate junctions. However, Asano et al. (12) found that C. elegans has no less than four different forms of claudins participating in the epithelial barrier. Cadherins form a superfamily with at least six distinct subfamilies: classical or type-I cadherins, atypical or type II cadherins, desmocollins, desmogleins, protocadherins, and Flamingo cadherins. In addition, several cadherins clearly occupy isolated positions in the cadherin superfamily (454). Nollet et al. (332) suggest a different evolutionary origin of the protocadherin and Flamingo cadherin genes versus the genes encoding desmogleins, desmocollins, classical cadherins, and atypical cadherins. In contrast to classic cadherins, which bind catenins by the cytoplasmic domains and have genes with as much as 12 introns, nonclassic cadherins do not interact with catenins and genes have many fewer introns (485). Phylogenetic analyses suggest that there are four paralogous

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

subfamilies (E-, N-, P-, and R-cadherins) of vertebrate classic cadherin proteins (168) and that these genes duplicated early in evolution (362). Amphioxus cadherin BbC localizes to adherens junctions in the ectodermal epithelia of embryos and confer homotypic adhesive properties. It has a cytoplasmic domain whose sequence is highly related to the cytoplasmic sequences of all known classic cadherins, but its extracellular domain lacks the classical five extracellular cadherin repeats and is similar to the extracellular domain of nonchordate cadherins (336). Choanoflagellates, a group of unicellular and colonial flagellates that resemble cells found only in Metazoa, express sequences of proteins that encode cadherin repeats. Phylogenetic analyses reveal that choanoflagellate cadherins are most similar to protocadherins and to the Flamingo class of cadherins, demonstrating that these proteins evolved before the origin of animals and were later co-opted for development (248). IX. THE DAWN OF METAZOANS AND TRANSPORTING EPITHELIA

1247

ture (e.g., D. discoideum) and migrate somewhere else. Likewise, organisms such as Porifera, without real tissues nor organs, have no internal milieu because the environment can circulate through the body, all cells can exchange directly with the environment, and should not concern us here. We refer instead to stable metazoans that survive thanks to an internal milieu whose stable composition depends on transporting epithelia. Although the fossil record starts some 560 – 600 million years ago, there is evidence that they were already existing as early as 800 –1,000 million years ago (104, 388). Ideas about metazoan phylogeny are numerous and somewhat conflicting (see Refs. 14, 104, 322, 323, 404, 475). Furthermore, our search for an ancestor of metazoans with true epithelia may start with a plausible idea of how such an organism should have been, regardless of whether it is still surviving or has been long extinct. The elaboration on a priori possible organisms might at least afford a useful working hypothesis to solve the conundrum mentioned in section I on the origins of metazoans and transporting epithelia. A. The “Thrifty Sponge”

The corelationship between multicellularity and transporting epithelia is stronger than the considerable variety of adaptative structures known to exist in many organisms. But a mere accumulation of cells might not qualify as metazoan. Thus, when nutrients are exhausted or wastes accumulate, cells may temporarily shut off their living processes, or form a transient multicellular struc-

It is conceivable that in a given moment a group of cells became surrounded by a primitive epithelium, i.e., one whose cells did not exhibit vectorial transport, but that attach and become an impermeable barrier (Fig. 6, top). Secreted molecules such as nutrients or cAMP may thereby be momentarily conserved and used as food stuff

FIG. 6. Hypothetical steps towards a metazoan surrounded by a transporting epithelium. Top panels: “thrifty sponge.” A: in a given moment, cells are surrounded by a primitive epithelial layer of nonpolarized cells, and secret a valuable substance (a nutrient? a signal?). The surrounding cells not only lack polarity, but do not have a selective permeability either. B: although cells profit from the valuable substance they secrete, the internal milieu is exhausted of nutrients and polluted by wastes. C: as a consequence of intoxication, or because an increase in osmolarity of the internal milieu bursts the “thrifty sponge,” the organism is flushed by the outer environment. D: a conglomerate of cells adopts a very flat structure and is surrounded by a primitive epithelium without specific permeability, yet the area-to-volume ratio is enough to ensure a satisfactory exchange with the environment. Peristaltic movements (arrow) might help stir the internal milieu. E: “mare nostrum.” A polarized cell divides. Its descendants stay attached to each other, generate an internal milieu, and because of the orientation of the mitotic spindle, all descendant cells have the same polarization. F: perpendicular orientation of the mitotic spindle provokes the development of an internal body of cells (pink). Alternatively, this development can be originated through a process resembling epithelialmesenchymal transition.

Physiol Rev • VOL

84 • OCTOBER 2004 •

www.prv.org

1248

CEREIJIDO, CONTRERAS, AND SHOSHANI

or signals, yet the entrapped milieu would gradually spoil and force a transient breakage of the epithelium, thus allowing the external medium to gain access to the cells and flush the organism. One may even conceive a certain synchrony between periods of secretion and epithelial tightness. In this respect, Green and Bergquist (193–195) have found that in sponges, cell junctions are apparently formed only when required for a specific purpose. B. Very Flat Organisms Another possibility would be a very flat organism with large surface-to-volume ratio, sufficient to allow exchange with the surroundings (Fig. 6, middle). Although these putative organisms might not have had circulatory apparatuses, peristaltic movements might have helped to stir the internal milieu and favor exchange. Actually, nature seems to have resorted to large surface-to-volume body plans and ease the survival of primitive metazoans. Thus Cnidaria, just one evolutionary step above sponges, have wide and flat structures. C. The “Mare Nostrum” Metazoans Up to this point we have been asking how did primeval metazoans develop their first epithelium. We cannot discard the opposite situation though. Because polarization is already observed in unicellulars, the possibility exists that an already polarized cell would proliferate without completing the separation of its descendants, and somehow profit from preserving an internal milieu (Fig. 6, bottom). Furthermore, proliferating epithelial cells usually have their mitotic spindle parallel to the surface of the epithelium so that proliferation expands the area of the organ (for a review, see Ref. 353). Yet when the spindle is perpendicular to the epithelium, it provokes the formation of an outgrowth similar in many respects to the body mass of a higher organism. X. Naⴙ-Kⴙ-ATPase AND CELL ADHESION

treated with EGTA, the chicken fence image of Na⫹-K⫹ATPase (Fig. 7A) splits into two moieties and each neighboring cell retrieves its own (Fig. 7B), indicating that each cell contributes the pumps and opening the possibility that these interact across the intercellular space. 2) In keeping with such conjunction, MDCK cells express Na⫹K⫹-ATPase at the lateral but not at the basal borders, as if only at the intercellular space the enzyme would find an attaching partner on an opposite cell. 3) When cocultured with Ma104 cells (epithelial from monkey kidney), an MDCK cell only expresses Na⫹-K⫹-ATPase in a given border provided its neighbor is another MDCK cell (Fig. 7C), suggesting that the putative Na⫹-K⫹-ATPase/Na⫹-K⫹ATPase interaction is a specific one (Fig. 5). 4) As mentioned above, Gloor et al. (180) have shown that the ␤2-subunit of glial cells acts as a cell adhesion molecule and has the corresponding structure: a short cytoplasmic tail, a single transmembrane domain, as well as long and glycosylated extracellular fragment. MDCK cells have instead the ␤1-isoform, but its structure is almost identical to that of ␤2. This suggests that the ␤-subunit of Na⫹-K⫹ATPase may establish a cell-cell contact as suggested in Figure 5. 5) Furthermore, this subunit is required for the formation of the septate junction of Drosophila (486). 6) As discussed below, the ␤-subunit of Na⫹-K⫹-ATPase does participate in cell attachment. On this basis, we have proposed that the polarized position of Na⫹-K⫹-ATPase at the lateral borders of epithelial cells depends on the binding ability of its ␤-subunit. The expression of this enzyme at the plasma membrane facing the intercellular space would be the only place where the ␤-subunits of neighboring cells can interact (77, 78, 98). This view has recently received experimental support from the studies illustrated in Figure 7, D and E. Briefly, it is observed that MDCK cells only express their ␤-subunits at the point of contact with another MDCK cell, but not in contacts with CHO fibroblasts. However, when CHO cells are transfected beforehand with ␤-subunit from the dog (i.e., same species as MDCK cells), MDCK cells now do express their ␤-subunits in heterotypic MDCK/CHO contacts.

A. Role of the ␤-Subunit in Cell Attachment

B. (P3 A), a Pump (P) Adhesion (A) Mechanism

Na⫹-K⫹-ATPase arrives to the lateral membrane, interacts with ankyrin, and becomes anchored to the cytoskeleton that stabilizes the enzyme in this position (206), yet we still ignore why this enzyme binds to the cytoskeleton at the lateral borders but does not bind to this structure when expressed at other cell borders. Furthermore, Na⫹-K⫹-ATPase in Drosophila epithelia does not bind to ankyrin but is nevertheless polarized (26). To develop a more plausible explanation, we took as hints that 1) when a monolayer of cultured MDCK cells is

Until a few years ago, it was assumed that, while synapses exchange valuable signals, contacts between other cell types were neutral and uneventful, and the role of cell attachment was reduced to secure the firm and definitive position of cells in a tissue. Then it was realized that attachments have to be somehow regulated, as revealed in the following circumstances: 1) when cells divide in the crypt of microvilli and migrate to the apex, and 2) cells of different types mixed in a suspension sort themselves spontaneously and group into islets of specific

Physiol Rev • VOL

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

1249

⫹ ⫹ FIG. 7. Patterns in the expression of Na -K ATPase in epithelial cells. A: in MDCK cells cultured in monolayers, Na⫹-K⫹-ATPase is expressed at the lateral borders, forming a chicken fence pattern. B: cell detachment provoked by 2.0 mM EGTA shows that each cell carries Na⫹-K⫹-ATPase in its borders, implying that the image in Figure 7A is given by the enzyme present in the two neighboring cells. C: a monolayer prepared with a mixed population of MDCK cells and Ma104 cells, which were previously stained with the red dye CMTMR. The use of a mouse antibody specific for the ␤-subunit of MDCK, followed by a goat antimouse fluoresceinated antibody, indicates that this subunit only occupies the cellular border of an MDCK cell, provided the neighboring cell is another MDCK one (green), but not when the border contacts an Ma104 cell. D: in mixtures of MDCK with CHO cells (fibroblasts derived from Chinese hamster ovary), MDCK cells only express Na⫹-K⫹-ATPases in homotypic (MDCK/MDCK) but not in heterotypic MDCK/ CHO borders (open arrows). However, when CHO cells are transfected beforehand with dog ␤-subunit, MDCK cells do express their ␤-subunits in heterotypic contacts (E, green arrows). Bar ⫽ 20 ␮m.

cell types. 3) The points where cells attach to a neighbor or to the substrate are like tips of icebergs sunk into the cytoplasm, whose molecules form scaffolds, associate with the cytoskeleton, send and receive specific molecules to the nucleus and other organelles, as well as exhibit the complex patterns of phosphorylation/dephosphorylation in specific amino acids that we mentioned above. 4) The nucleus changes the pattern of gene expression in response to the arrival of the NACos (Fig. 3, Table 1). 5) After severing the attachment with its neighbors, cells may undergo proliferation, differentiation, migration, or apoptosis, in which batteries of genes are turned on or off. 6) The differentiation of a given cell type depends on the nature of contacts with its neighbors. Nowhere is this process more astonishing than in the self-assembly of a brain, where genes, by obeying just chemical rules, produce the most complex three-dimensional ordered object known, depending on the species of attaching molecules coded, and the timing of their expression in axons and dendrites of the neurons. 7) There is a growing amount of evidence of cancers and autoimmune diseases associated with failures in molecules involved in cell contacts (76, 77, 182). On this basis we tentatively attribute the very emergence of metazoans to special combinations of attachments between specific cells as well as between specific molecules. Physiol Rev • VOL

In keeping with the importance of the processes mentioned in the previous paragraph, cell-cell attachment seems to be strictly regulated. Yet the information presently available on this regulation is very scant. We found a mechanisms termed P3 A, which transduces the occupancy of the Na⫹-K⫹-ATPase (P) by ouabain, into a signaling to molecules involved in cell-cell and cell-substrate attachment (A), that prompts these to release the grip and results in detachment of the cell (102). Thus MDCK cells treated with ouabain increase Tyr phosphorylation and content of active MAPK, redistribute molecules involved in cell attachment (occludin, ZO-1, desmoplakin, cytokeratin, ␤-actinin, vinculin, and actin), and detach. Genistein and UO126, inhibitors of protein tyrosine kinase and MAPK kinase, respectively, block this detachment. The content of P190Rho-GAP, a GTPase activating protein of the Rho small G protein subfamily, is increased by ouabain, suggesting that both the Rho/Rac and MAPK pathways may be involved. The P3 A mechanism may play several potential roles, in views of the following: 1) damaged epithelial cells endanger the permeability barrier between higher organisms and the environment. An injured cell would conceivably produce less ATP, the activity of the Na⫹-K⫹ATPase would decrease, thus triggering the P3 A mechanism that promotes its own detachment and replace-

84 • OCTOBER 2004 •

www.prv.org

1250

CEREIJIDO, CONTRERAS, AND SHOSHANI

ment. 2) Because junctions help maintain the architecture of tissues by holding neighboring cells, they would need to relax the grip whenever a change in the position of the cells is required. A few situations in which such relax would be needed are as follows: 1) during the healing of a wound, cells proliferate and migrate to occupy the space left by dead cells; 2) some tissues minimize the risks derived from errors in proliferation by restricting cell division to stem cells, and to regularly shed the mature cells of the progeny. Thus in the frog skin cells originate in the innermost stratum of the multilayered epithelium (stratum germinativum), migrate towards the outside, and only establish occluding junctions in the very last stages, as the permeability barrier thus established impairs the nutrition of all cells located beyond this point (stratum corneum). Cells of this stratus detach simultaneously and molt under the control of the hypophysis. 3) During organogenesis the various cell types involved undergo a wide range of proliferation rates and distribution that enable them to adopt the typical architecture of a given tissue. These migrations and positioning would be favored by a P3 A mechanism that relaxes the adhesion between neighboring cells in a specific manner. Conceivably, this relaxation may be cell specific if each cell expresses a given isoform of ␣-subunit with different sensitivity to ouabain (42, 234), i.e., with different ability to detach when challenged by the hormone through the P3 A mechanism. 4) Adhesion may be suspected to play a role in the development of metastasis, as cells must dislodge themselves from the mass of the main tumor and home among the cells of a distant organ. 3) Actually, the response to ouabain challenge depends on the type of cell involved. Thus it may cause apoptosis in MDCK cells from dogs, but not in Ma104 from monkeys, which may even protect the former in cocultures (45, 98, 99, 346). 4) Both pumping and enzymatic activity of the Na⫹-K⫹-ATPase can be specifically inhibited by the cardiac glycoside ouabain (397, 417) that binds to an extracellular site of its ␣-subunit with a high affinity (Km ⬍ 10⫺8 M). However, there is growing evidence that ouabain is a hormone normally present in the blood (403). Therefore, it is conceivable that detachment and removal of a given cell type may be also promoted by endogenous ouabain-like substances (403). 5) Metastases start by a detachment of cancer cells from the mass of the main tumor. Furthermore, Ward et al. (469) have recently described the union of ouabain to a receptor different from Na⫹-K⫹-ATPase whose function is not yet elucidated, suggesting that, eventually, the P3 A mechanism may be found to be triggered through a receptor other than the ␣-subunit of the Na⫹-K⫹-ATPase. Obviously, once the P3 A mechanism has completely detached, a cell from its neighbors and from the substrate, all exchange of information is interrupted. Yet this is an extreme situation produced by relatively high concentraPhysiol Rev • VOL

tions of ouabain, but there are a variety of cell-cell contacts, as well as subtler degrees of detachment. Figure 3 illustrates the case of a NACo (␤-catenin) that is addressed to the nucleus by ouabain, and another that is not (ZO-1). Taken together, this information suggests that by expressing a variety of ␣-subunits with different ouabain sensitivities (214, 385, 438), the Na⫹-K⫹-ATPase may be controlled by the hormone ouabain, and activate a P3 A mechanism that deeply modifies the structure and function of a given cell. In summary, we cannot provide an answer to the question raised in section I about the origin of transporting epithelia and metazoans, but after systematizing the information obtained from widely heterogeneous fields, it seems that ancestral unicellulars already possessed most of the precursor molecules to build up transporting epithelia and form a perhaps transient metazoan that evolution might subject to selective pressures. Attachment, both at the molecular and the cellular level, seems to have played a paramount role. We thank Dr. Catalina Flores-Maldonado and Lic. Isabel Larre´ for helpful discussion and furnishing their unpublished results in Figure 3, B–E. We also acknowledge the efficient and pleasant help of Elizabeth del Oso. This work was supported by the National Research Council of Mexico (CONACYT). Address for reprint requests and other correspondence: M. Cereijido, Center For Research and Advanced Studies, Dept. of Physiology, Biophysics, and Neurosciences, Avenida Instituto Polite´ cnico Nacional 2508, Co´ digo Postal 07360, Me´ xico D.F., Mexico (E-mail: [email protected]).

REFERENCES 1. Aberle H, Bauer A, Stappert J, Kispert A, and Kemler R. Beta-catenin is a target for the ubiquitin-proteasome pathway. EMBO J 16: 3797–3804, 1997. 2. Ackermann U and Geering K. Mutual dependence of Na,KATPase alpha- and beta-subunits for correct posttranslational processing and intracellular transport. FEBS Lett 269: 105–108, 1990. 3. Adams CL and Nelson WJ. Cytomechanics of cadherin-mediated cell-cell adhesion. Curr Opin Cell Biol 10: 572–577, 1998. 4. Ahearn GA, Duerr JM, Zhuang Z, Brown RJ, Aslamkhan A, and Killebrew DA. Ion transport processes of crustacean epithelial cells. Physiol Biochem Zool 72: 1–18, 1999. 5. Anderson JM, Stevenson BR, Jesaitis LA, Goodenough DA, and Mooseker MS. Characterization of ZO-1, a protein component of the tight junction from mouse liver and Madin-Darby canine kidney cells. J Cell Biol 106: 1141–1149, 1988. 6. Angres B, Muller AH, Kellermann J, and Hausen P. Differential expression of two cadherins in Xenopus laevis. Development 111: 829 – 844, 1991. 7. Antonetti DA, Barber AJ, Hollinger LA, Wolpert EB, and Gardner TW. Vascular endothelial growth factor induces rapid phosphorylation of tight junction proteins occludin and zonula occluden 1. A potential mechanism for vascular permeability in diabetic retinopathy and tumors. J Biol Chem 274: 23463–23467, 1999. 8. Antonicek H, Persohn E, and Schachner M. Biochemical and functional characterization of a novel neuron-glia adhesion molecule that is involved in neuronal migration. J Cell Biol 104: 1587– 1595, 1987.

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS 9. Antonicek H and Schachner M. The adhesion molecule on glia (AMOG) incorporated into lipid vesicles binds to subpopulations of neurons. J Neurosci 8: 2961–2966, 1988. 10. Arystarkhova E, Wetzel RK, Asinovski NK, and Sweadner KJ. The gamma subunit modulates Na(⫹) and K(⫹) affinity of the renal Na,K-ATPase. J Biol Chem 274: 33183–33185, 1999. 11. Arystarkhova E, Wetzel RK, and Sweadner KJ. Distribution and oligomeric association of splice forms of Na(⫹)-K(⫹)-ATPase regulatory gamma-subunit in rat kidney. Am J Physiol Renal Physiol 282: F393–F407, 2002. 12. Asano A, Asano K, Sasaki H, Furuse M, and Tsukita S. Claudins in Caenorhabditis elegans: their distribution and barrier function in the epithelium. Curr Biol 13: 1042–1046, 2003. 13. Avila-Flores A, Rendon-Huerta E, Moreno J, Islas S, Betanzos A, Robles-Flores M, and Gonzalez-Mariscal L. Tight-junction protein zonula occludens 2 is a target of phosphorylation by protein kinase C. Biochem J 360: 295–304, 2001. 14. Ax P. The hierarchy of life, molecules and morphology in phyligenetic analisis. In: Fernholm. Amsterdam: Excepta Medica, 1989, p. 229 –245. 15. Axelsen KB and Palmgren MG. Evolution of substrate specificities in the P-type ATPase superfamily. J Mol Evol 46: 84 –101, 1998. 16. Baas AF, Kuipers J, Van Der Wel NN, Batlle E, Koerten HK, Peters JP, and Clevers HC. Complete polarization of single intestinal epithelial cells upon activation of LKB1 by STRAD. Cell 116: 457– 466, 2004. 17. Balda MS and Anderson JM. Two classes of tight junctions are revealed by ZO-1 isoforms. Am J Physiol Cell Physiol 264: C918 – C924, 1993. 18. Balda MS, Anderson JM, and Matter K. The SH3 domain of the tight junction protein ZO-1 binds to a serine protein kinase that phosphorylates a region C-terminal to this domain. FEBS Lett 399: 326 –332, 1996. 19. Balda MS, Garrett MD, and Matter K. The ZO-1-associated Y-box factor ZONAB regulates epithelial cell proliferation and cell density. J Cell Biol 160: 423– 432, 2003. 20. Balda MS, Gonzalez-Mariscal L, Contreras RG, Macias-Silva M, Torres-Marquez ME, Garcia-Sainz JA, and Cereijido M. Assembly and sealing of tight junctions: possible participation of G-proteins, phospholipase C, protein kinase C and calmodulin. J Membr Biol 122: 193–202, 1991. 21. Balda MS, Gonzalez-Mariscal L, Matter K, Cereijido M, and Anderson JM. Assembly of the tight junction: the role of diacylglycerol. J Cell Biol 123: 293–302, 1993. 22. Balda MS and Matter K. The tight junction protein ZO-1 and an interacting transcription factor regulate ErbB-2 expression. EMBO J 19: 2024 –2033, 2000. 23. Balda MS and Matter K. Epithelial cell adhesion and the regulation of gene expression. Trends Cell Biol 13: 310 –318, 2003. 24. Balda MS, Whitney JA, Flores C, Gonzalez S, Cereijido M, and Matter K. Functional dissociation of paracellular permeability and transepithelial electrical resistance and disruption of the apical-basolateral intramembrane diffusion barrier by expression of a mutant tight junction membrane protein. J Cell Biol 134: 1031–1049, 1996. 25. Barriere H, Chambard M, Selzner JP, Mauchamp J, and Gabrion J. Polarity reversal of inside-out thyroid follicles cultured within collagen gel: structure of the junctions assessed by freezefracture and lanthanum permeability. Biol Cell 62: 133–144, 1988. 26. Baumann O. Biogenesis of surface domains in fly photoreceptor cells: fine-structural analysis of the plasma membrane and immunolocalization of Na⫹, K⫹ ATPase and alpha-spectrin during cell differentiation. J Comp Neurol 382: 429 – 442, 1997. 27. Baumann O, Lautenschlager B, and Takeyasu K. Immunolocalization of Na,K-ATPase in blowfly photoreceptor cells. Cell Tissue Res 275: 225–234, 1994. 28. Bazzoni G, Martinez-Estrada OM, Orsenigo F, Cordenonsi M, Citi S, and Dejana E. Interaction of junctional adhesion molecule with the tight junction components ZO-1, cingulin, and occludin. J Biol Chem 275: 20520 –20526, 2000. 29. Beggah AT, Beguin P, Jaunin P, Peitsch MC, and Geering K. Hydrophobic C-terminal amino acids in the beta-subunit are inPhysiol Rev • VOL

30.

31.

32.

33.

34.

35.

36.

37.

38. 39.

40.

41.

42.

43.

44.

45.

46.

47. 48.

1251

volved in assembly with the alpha-subunit of Na,K-ATPase. Biochemistry 32: 14117–14124, 1993. Beggah AT, Jaunin P, and Geering K. Role of glycosylation and disulfide bond formation in the beta subunit in the folding and functional expression of Na,K-ATPase. J Biol Chem 272: 10318 – 10326, 1997. Beguin P, Crambert G, Guennoun S, Garty H, Horisberger JD, and Geering K. Chif, a member of the FXYD protein family, is a regulator of Na,K-ATPase distinct from the gamma-subunit. EMBO J 20: 3993– 4002, 2001. Beguin P, Crambert G, Monnet-Tschudi F, Uldry M, Horisberger JD, Garty H, and Geering K. Fxyd7 is a brain-specific regulator of Na,K-ATPase alpha 1-beta isozymes. EMBO J 21: 3264 – 3273, 2002. Behr M, Riedel D, and Schuh R. The claudin-like megatrachea is essential in septate junctions for the epithelial barrier function in Drosophila. Dev Cell 5: 611– 620, 2003. Behrens J, Birchmeier W, Goodman SL, and Imhof BA. Dissociation of Madin-Darby canine kidney epithelial cells by the monoclonal antibody anti-arc-1: mechanistic aspects and identification of the antigen as a component related to uvomorulin. J Cell Biol 101: 1307–1315, 1985. Behrens J, Frixen U, Schipper J, Weidner M, and Birchmeier W. Cell adhesion in invasion and metastasis. Semin Cell Biol 3: 169 –178, 1992. Behrens J, Lowrick O, Klein-Hitpass L, and Birchmeier W. The E-cadherin promoter: functional analysis of a GC-rich region and an epithelial cell-specific palindromic regulatory element. Proc Natl Acad Sci USA 88: 11495–11499, 1991. Behrens J, Von Kries JP, Kuhl M, Bruhn L, Wedlich D, Grosschedl R, and Birchmeier W. Functional interaction of beta-catenin with the transcription factor LEF-1. Nature 382: 638 – 642, 1996. Bellairs R. Developmental and Evolutionary Aspects of Neural Crest, edited by Manderson P. New York: Wiley, 1987, p. 123–145. Ben Yosef T, Belyantseva IA, Saunders TL, Hughes ED, Kawamoto K, Van Itallie CM, Beyer LA, Halsey K, Gardner DJ, Wilcox ER, Rasmussen J, Anderson JM, Dolan DF, Forge A, Raphael Y, Camper SA, and Friedman TB. Claudin 14 knockout mice, a model for autosomal recessive deafness DFNB29, are deaf due to cochlear hair cell degeneration. Hum Mol Genet 12: 2049 –2061, 2003. Betanzos A, Huerta M, Lopez-Bayghen E, Azuara E, Amerena J, and Gonzalez-Mariscal L. The tight junction protein ZO-2 associates with Jun, Fos and C/EBP transcription factors in epithelial cells. Exp Cell Res 292: 51– 66, 2004. Blanco G, Melton RJ, Sanchez G, and Mercer RW. Functional characterization of a testes-specific alpha-subunit isoform of the sodium/potassium adenosinetriphosphatase. Biochemistry 38: 13661–13669, 1999. Blanco G and Mercer RW. Isozymes of the Na-K-ATPase: heterogeneity in structure, diversity in function. Am J Physiol Renal Physiol 275: F633–F650, 1998. Bok D. Autoradiographic studies on the polarity of plasma membrane receptors in retinal pigment epithelial cells. In: The Structure of the Eye, edited by Hollyfield JG. New York: Elsevier Biomedical, 1982, p. 245–256. Bok D, O’Day W, and Rodriguez-Boulan E. Polarized budding of vesicular stomatitis and influenza virus from cultured human and bovine retinal pigment epithelium. Exp Eye Res 55: 853– 860, 1992. Bolivar JJ, Lazaro A, Fernandez S, Stefani E, Pena-Cruz V, Lechene C, and Cereijido M. Rescue of a wild-type MDCK cell by a ouabain-resistant mutant. Am J Physiol Cell Physiol 253: C151– C161, 1987. Boulan ER, Ques-Von Petery MV, Rotunno CA, and Cereijido M. Studies on chloride permeability of the skin of Leptodactylus ocellatus. III. Na⫹ and Cl⫺ effect on electrical phenomena. J Membr Biol 42: 345–356, 1978. Boulpaep EL and Sackin H. Electrical analysis of intraepithelial barriers. Curr Top Membr Transp 13: 169, 1980. Bullivant S. The structure of tight junctions, in electron microscopy III. In: Int Cong Electron Microsc 9th Toronto Canada 1978, p. 659.

84 • OCTOBER 2004 •

www.prv.org

1252

CEREIJIDO, CONTRERAS, AND SHOSHANI

49. Burns AR, Walker DC, and Wayne Smith C. Relationship between tight junctions and leucocyte transmigration. In: Tight Junctions, edited by Cereijido M and Anderson JM. Boca Raton, FL.: CRC, 2001, p. 629 – 652. 50. Calderon V, Lazaro A, Contreras RG, Shoshani L, FloresMaldonado C, Gonzalez-Mariscal L, Zampighi G, and Cereijido M. Tight junctions and the experimental modifications of lipid content. J Membr Biol 164: 59 – 69, 1998. 51. Caldwell RB and McLaughlin BJ. Redistribution of Na-K-ATPase in the dystrophic rat retinal pigment epithelium. J Neurocytol 13: 895–910, 1984. 52. Cameron R, Klein L, Shyjan AW, Rakic P, and Levenson R. Neurons and astroglia express distinct subsets of Na,K-ATPase alpha and beta subunits. Brain Res 21: 333–343, 1994. 53. Cano A, Perez-Moreno MA, Rodrigo I, Locascio A, Blanco MJ, Del Barrio MG, Portillo F, and Nieto MA. The transcription factor snail controls epithelial-mesenchymal transitions by repressing E-cadherin expression. Nat Cell Biol 2: 76 – 83, 2000. 54. Caplan MJ, Anderson HC, Palade GE, and Jamieson JD. Intracellular sorting and polarized cell surface delivery of (Na⫹, K⫹)ATPase, an endogenous component of MDCK cell basolateral plasma membranes. Cell 46: 623– 631, 1986. 55. Caplan MJ, Palade GE, and Jamieson JD. Newly synthesized Na,K-ATPase alpha-subunit has no cytosolic intermediate in MDCK cells. J Biol Chem 261: 2860 –2865, 1986. 56. Cereijido M. Tight Junctions (1st ed.). Boca Raton, FL: CRC, 1992. 57. Cereijido M. Evolution of the ideas on the tight junction. In: Tight Junctions, edited by Cereijido M and Anderson JM. Boca Raton, FL: CRC, 2001, p. 1–18. 58. Cereijido M and Anderson JM. Tight Junctions (2nd ed.). Boca Raton, FL: CRC, 2001, p. 1–772. 59. Cereijido M, Contreras RG, Shoshani L, and Garcia-Villegas MR. Membrane targeting. Prog Biophys Mol Biol 81: 81–115, 2003. 60. Cereijido M and Curran PF. Intracellular electrical potentials in frog skin. J Gen Physiol 48: 543–557, 1965. 61. Cereijido M, Ehrenfeld J, Fernandez-Castelo S, and Meza I. Fluxes, junctions, and blisters in cultured monolayers of epithelioid cells (MDCK). Ann NY Acad Sci 372: 422– 441, 1981. 62. Cereijido M, Ehrenfeld J, Meza I, and Martinez-Palomo A. Structural and functional membrane polarity in cultured monolayers of MDCK cells. J Membr Biol 52: 147–159, 1980. 63. Cereijido M, Gonzalez-Mariscal L, Avila G, and Contreras RG. Tight junction. CRC Crit Rev Anat Sci 1: 171–192, 1988. 64. Cereijido M, Herrera FC, Flanigan WJ, and Curran PF. The influence of Na concentration on Na transport across frog skin. J Gen Physiol 47: 879 – 893, 1964. 65. Cereijido M, Moreno JH, Reisin I, Boulan ER, Rotunno CA, and Zylber EA. On the mechanism of sodium movement across epithelia. Ann NY Acad Sci 204: 310 –324, 1973. 66. Cereijido M, Ponce A, and Gonzalez-Mariscal L. Tight junctions and apical/basolateral polarity. J Membr Biol 110: 1–9, 1989. 67. Cereijido M, Rabito CA, Boulan ER, and Rotunno CA. The sodium-transporting compartment of the epithelium of frog skin. J Physiol 237: 555–571, 1974. 68. Cereijido M, Reisin I, and Rotunno CA. The effect of sodium concentration on the content and distribution of sodium in the frog skin. J Physiol 196: 237–253, 1968. 69. Cereijido M, Robbins ES, Dolan WJ, Rotunno CA, and Sabatini DD. Polarized monolayers formed by epithelial cells on a permeable and translucent support. J Cell Biol 77: 853– 880, 1978. 70. Cereijido M, Robbins ES, Rotunno CA, Dolan DF, and Sabatini DD. Membrane properties of cells of renal origin (MDCK) cultured in monolayers on a permeable and translucent support (Abstract). Proc Int Union Physiol 12: 250a, 1977. 71. Cereijido M and Rotunno CA. Transport and distribution of sodium across frog skin. J Physiol 190: 481– 497, 1967. 72. Cereijido M and Rotunno CA. Introduction to the Study of Biological Membranes. New York: Gordon and Breach, 1971, p. 1–261. 73. Cereijido M and Rotunno CA. The effect of antidiuretic hormone on Na movement across frog skin. J Physiol 213: 119 –133, 1971. Physiol Rev • VOL

74. Cereijido M, Rotunno CA, Robbins ES, and Sabatini DD. In vitro formation of cell layers with properties of epithelial membranes (Abstract). Biophys J 17: 22a, 1977. 75. Cereijido M, Rotunno CA, Robbins ES, and Sabatini DD. Polarized epithelial membranes produced in vitro. In: Membrane Transport Processes. New York: Raven, 1978, p. 433– 443. 76. Cereijido M, Shoshani L, and Contreras RG. Molecular physiology and pathophysiology of tight junctions. I. Biogenesis of tight junctions and epithelial polarity. Am J Physiol Gastrointest Liver Physiol 279: G477–G482, 2000. 77. Cereijido M, Shoshani L, and Contreras RG. The polarized distribution of Na⫹-K⫹-ATPase and active transport across epithelia. J Membr Biol 184: 299 –304, 2001. 78. Cereijido M, Stefani E, and Palomo AM. Occluding junctions in a cultured transporting epithelium: structural and functional heterogeneity. J Membr Biol 53: 19 –32, 1980. 79. Chen Y, Lu Q, Schneeberger EE, and Goodenough DA. Restoration of tight junction structure and barrier function by downregulation of the mitogen-activated protein kinase pathway in rastransformed Madin-Darby canine kidney cells. Mol Biol Cell 11: 849 – 862, 2000. 80. Chen YT, Stewart DB, and Nelson WJ. Coupling assembly of the E-cadherin/beta-catenin complex to efficient endoplasmic reticulum exit and basal-lateral membrane targeting of E-cadherin in polarized MDCK cells. J Cell Biol 144: 687– 699, 1999. 81. Cheng CY and Mruk DD. Cell junction dynamics in the testis: Sertoli-germ cell interactions and male contraceptive development. Physiol Rev 82: 825– 874, 2002. 82. Chlenski A, Ketels KV, Engeriser JL, Talamonti MS, Tsao MS, Koutnikova H, Oyasu R, and Scarpelli DG. ZO-2 gene alternative promoters in normal and neoplastic human pancreatic duct cells. Int J Cancer 83: 349 –358, 1999. 83. Chlenski A, Ketels KV, Korovaitseva GI, Talamonti MS, Oyasu R, and Scarpelli DG. Organization and expression of the human zo-2 gene (tjp-2) in normal and neoplastic tissues. Biochim Biophys Acta 1493: 319 –324, 2000. 84. Chlenski A, Ketels KV, Tsao MS, Talamonti MS, Anderson MR, Oyasu R, and Scarpelli DG. Tight junction protein ZO-2 is differentially expressed in normal pancreatic ducts compared with human pancreatic adenocarcinoma. Int J Cancer 82: 137–144, 1999. 85. Citi S. Protein kinase inhibitors prevent junction dissociation induced by low extracellular calcium in MDCK epithelial cells. J Cell Biol 117: 169 –178, 1992. 86. Citi S and Cordenonsi M. The molecular basis for the structure, function, and regulation of tight junctions. Adv Mol Cell Biol 28: 203–233, 1999. 87. Citi S and Denisenko N. Phosphorylation of the tight junction protein cingulin and the effects of protein kinase inhibitors and activators in MDCK epithelial cells. J Cell Sci 108: 2917–2926, 1995. 88. Citi S, Sabanay H, Jakes R, Geiger B, and Kendrick-Jones J. Cingulin, a new peripheral component of tight junctions. Nature 333: 272–276, 1988. 89. Clarke H, Soler AP, and Mullin JM. Protein kinase C activation leads to dephosphorylation of occludin and tight junction permeability increase in LLC-PK1 epithelial cell sheets. J Cell Sci 113: 3187–3196, 2000. 90. Clarke HM, Soler AP, and Mullin JM. Activation of protein kinase C by the phorbol ester, TPA, leads to an incrase in tight junction permeability and a decrease in the threonine phosphorylation of occludin in LLC-PK1 cells (Abstract). FASEB J 15: A139, 2001. 91. Claude P. Morphological factors influencing transepithelial permeability: a model for the resistance of the zonula occludens. J Membr Biol 39: 219 –232, 1978. 92. Claude P and Goodenough DA. Fracture faces of zonulae occludentes from “tight” and “leaky” epithelia. J Cell Biol 58: 390 – 400, 1973. 93. Colegio OR, Van Itallie C, Rahner C, and Anderson JM. Claudin extracellular domains determine paracellular charge selectivity and resistance but not tight junction fibril architecture. Am J Physiol Cell Physiol 284: C1346 –C1354, 2003. 94. Colegio OR, Van Itallie CM, Mccrea HJ, Rahner C, and Anderson JM. Claudins create charge-selective channels in the paracel-

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

95.

96.

97.

98.

99.

100.

101.

102.

103.

104. 105.

106.

107.

108.

109.

110.

111.

112. 113. 114. 115.

lular pathway between epithelial cells. Am J Physiol Cell Physiol 283: C142–C147, 2002. Colonna TE, Huynh L, and Fambrough DM. Subunit interactions in the Na,K-ATPase explored with the yeast two-hybrid system. J Biol Chem 272: 12366 –12372, 1997. Contreras RG, Avila G, Gutierrez C, Bolivar JJ, GonzalezMariscal L, Darzon A, Beaty G, Rodriguez-Boulan E, and Cereijido M. Repolarization of Na⫹-K⫹ pumps during establishment of epithelial monolayers. Am J Physiol Cell Physiol 257: C896 –C905, 1989. Contreras RG, Gonzalez-Mariscal L, Balda MS, Garcia-Villegas MR, and Cereijido M. The role of calcium in the making of a transporting epithelium. News Physiol Sci 7: 105–108, 1992. Contreras RG, Lazaro A, Bolivar JJ, Flores-Maldonado C, Sanchez SH, Gonzalez-Mariscal L, Garcia-Villegas MR, Valdes J, and Cereijido M. A novel type of cell-cell cooperation between epithelial cells. J Membr Biol 145: 305–310, 1995. Contreras RG, Lazaro A, Mujica A, Gonzalez-Mariscal L, Valdes J, Garcia-Villegas MR, and Cereijido M. Ouabain resistance of the epithelial cell line (Ma104) is not due to lack of affinity of its pumps for the drug. J Membr Biol 145: 295–300, 1995. Contreras RG, Miller JH, Zamora M, Gonzalez-Mariscal L, and Cereijido M. Interaction of calcium with plasma membrane of epithelial (MDCK) cells during junction formation. Am J Physiol Cell Physiol 263: C313–C318, 1992. Contreras RG, Ponce A, and Bolivar JJ. Calcium and tight junctions. In: Tight Junctions, edited by Cereijido M. Boca Raton, FL: CRC, 1992, p. 139 –149. Contreras RG, Shoshani L, Flores-Maldonado C, Lazaro A, and Cereijido M. Relationship between Na(⫹), K(⫹)-ATPase and cell attachment. J Cell Sci 112: 4223– 4232, 1999. Contreras RG, Shoshani L, Flores-Maldonado C, Lazaro A, Monroy Ao, Roldan ML, Fiorentino R, and Cereijido M. ECadherin and tight junctions between epithelial cells of different animal species. Pflu¨ gers Arch 444: 467– 475, 2002. Conway Morris S. The fossil record and the early evolution of metazoa. Nature 361: 219 –225, 1993. Cordenonsi M, D’atri F, Hammar E, Parry DA, KendrickJones J, Shore D, and Citi S. Cingulin contains globular and coiled-coil domains and interacts with ZO-1, ZO-2, ZO-3, and myosin. J Cell Biol 147: 1569 –1582, 1999. Cordenonsi M, Turco F, D’atri F, Hammar E, Martinucci G, Meggio F, and Citi S. Xenopus laevis occludin. Identification of in vitro phosphorylation sites by protein kinase CK2 and association with cingulin. Eur J Biochem 264: 374 –384, 1999. Cornell JC. Sodium and chloride transport in the isolated intestine of the earthworm, Lumbricus terrestris (L.). J Exp Biol 97: 197–216, 1982. Crambert G, Beguin P, Pestov NB, Modyanov NN, and Geering K. Betam, a structural member of the X, K-ATPase beta subunit family, resides in the ER and does not associate with any known X, K-ATPase alpha subunit. Biochemistry 41: 6723– 6733, 2002. Crambert G, Hasler U, Beggah AT, Yu C, Modyanov NN, Horisberger JD, Lelievre L, and Geering K. Transport and pharmacological properties of nine different human Na,K-ATPase isozymes. J Biol Chem 275: 1976 –1986, 2000. Cramer EB, Milks LC, and Ojakian GK. Transepithelial migration of human neutrophils: an in vitro model system. Proc Natl Acad Sci USA 77: 4069 – 4073, 1980. Crane RK, Forstner G, and Eichholz A. Studies on the mechanism of the intestinal absorption of sugars. X. An effect of Na⫹ concentration on the apparent Michaelis constants for intestinal sugar transport, in vitro. Biochim Biophys Acta 109: 467– 477, 1965. Csaky TZ and Thale M. Effect of ionic environment on intestinal sugar transport. J Physiol 151: 59 – 65, 1960. Curran PF and Cereijido M. K fluxes in frog skin. J Gen Physiol 48: 1011–1033, 1965. D’Atri F and Citi S. Cingulin interacts with F-actin in vitro. FEBS Lett 507: 21–24, 2001. D’Atri F, Nadalutti F, and Citi S. Evidence for a functional interaction between cingulin and ZO-1 in cultured cells. J Biol Chem 277: 27757–27764, 2002. Physiol Rev • VOL

1253

116. Dedhar S, Rennie PS, Shago M, Hagesteijn CY, Yang H, Filmus J, Hawley RG, Bruchovsky N, Cheng H, and Matusik RJ. Inhibition of nuclear hormone receptor activity by calreticulin. Nature 367: 480 – 483, 1994. 117. De Donder T and Van Rysselberghe P. The Thermodynamic Theory of Affinity. Stanford, CA: Stanford Univ. Press, 1936. 118. Demaio L, Chang YS, Gardner TW, Tarbell JM, and Antonetti DA. Shear stress regulates occludin content and phosphorylation. Am J Physiol Heart Circ Physiol 281: H105–H113, 2001. 119. Denker BM, Saha C, Khawaja S, and Nigam SK. Involvement of a heterotrimeric G protein alpha subunit in tight junction biogenesis. J Biol Chem 271: 25750 –25753, 1996. 120. Devarajan P, Scaramuzzino DA, and Morrow JS. Ankyrin binds to two distinct cytoplasmic domains of Na,K-ATPase alpha subunit. Proc Natl Acad Sci USA 91: 2965–2969, 1994. 121. Diamond JM. The mechanism of solute transport by the gallbladder. J Physiol (Paris) 161: 474 –502, 1962. 122. Diamond JM. Transport mechanisms in the gallbladder. In: Handbook of Physiology. The Alimentary Canal. Washington, DC: Am. Physiol. Soc., 1968, sect. 6, p. 2451. 123. Diamond JM and Wright EM. Biological membranes: the physical basis of ion and nonelectrolyte selectivity. Annu Rev Physiol 31: 581– 646, 1969. 124. Dobrosotskaya I, Guy RK, and James GL. Magi-1, a membraneassociated guanylate kinase with a unique arrangement of proteinprotein interaction domains. J Biol Chem 272: 31589 –31597, 1997. 125. Dodane V and Kachar B. Identification of isoforms of G proteins and PKC that colocalize with tight junctions. J Membr Biol 149: 199 –209, 1996. 126. Dragsten PR, Blumenthal R, and Handler JS. Membrane asymmetry in epithelia: is the tight junction a barrier to diffusion in the plasma membrane? Nature 294: 718 –722, 1981. 127. Dragsten PR, Handler JS, and Blumenthal R. Fluorescent membrane probes and the mechanism of maintenance of cellular asymmetry in epithelia. Federation Proc 41: 48 –53, 1982. 128. Dubreuil RR, Maddux PB, Grushko TA, and Macvicar GR. Segregation of two spectrin isoforms: polarized membrane-binding sites direct polarized membrane skeleton assembly. Mol Biol Cell 8: 1933–1942, 1997. 129. Dubreuil RR, Wang P, Dahl S, Lee J, and Goldstein LS. Drosophila beta spectrin functions independently of alpha spectrin to polarize the Na,K ATPase in epithelial cells. J Cell Biol 149: 647– 656, 2000. 130. Dunbar LA, Aronson P, and Caplan MJ. A transmembrane segment determines the steady-state localization of an ion-transporting adenosine triphosphatase. J Cell Biol 148: 769 –778, 2000. 131. Dunbar LA and Caplan MJ. The cell biology of ion pumps: sorting and regulation. Eur J Cell Biol 79: 557–563, 2000. 132. Ebnet K, Schulz CU, Meyer ZU, Brickwedde MK, Pendl GG, and Vestweber D. Junctional adhesion molecule interacts with the PDZ domain-containing proteins AF-6 and ZO-1. J Biol Chem 275: 27979 –27988, 2000. 133. Ebnet K, Suzuki A, Horikoshi Y, Hirose T, Meyer ZU, Brickwedde MK, Ohno S, and Vestweber D. The cell polarity protein ASIP/PAR-3 directly associates with junctional adhesion molecule (JAM). EMBO J 20: 3738 –3748, 2001. 134. Ernst SA and Mills JW. Basolateral plasma membrane localiztion of ouabain-sensitive sodium transport sites in the secretory epithelium of the avian salt gland. J Cell Biol 75: 74 –94, 1977. 135. Ernst SA and Mills JW. Autoradiographic localization of tritiated ouabain-sensitive sodium pump sites in ion transporting epithelia. J Histochem Cytochem 28: 72–77, 1980. 136. Esmann M. The distribution of C12E8-solubilized oligomers of the (Na⫹ ⫹ K⫹)-ATPase. Biochim Biophys Acta 787: 81– 89, 1984. 137. Esmann M and Skou JC. Kinetic properties of C12E8-solubilized (Na⫹ ⫹ K⫹)-ATPase. Biochim Biophys Acta 787: 71– 80, 1984. 138. Fahraeus R and Lane DP. The p16(INK4a) tumour suppressor protein inhibits alphavbeta3 integrin-mediated cell spreading on vitronectin by blocking PKC-dependent localization of alphavbeta3 to focal contacts. EMBO J 18: 2106 –2118, 1999. 139. Fambrough DM and Bayne EK. Multiple forms of (Na⫹ ⫹ K⫹)ATPase in the chicken. Selective detection of the major nerve,

84 • OCTOBER 2004 •

www.prv.org

1254

140.

141.

142.

143.

144.

145.

146.

147.

148. 149.

150.

151.

152.

153.

154.

155.

156.

157.

158.

159.

CEREIJIDO, CONTRERAS, AND SHOSHANI

skeletal muscle, and kidney form by a monoclonal antibody. J Biol Chem 258: 3926 –3935, 1983. Fambrough DM, Lemas MV, Hamrick M, Emerick M, Renaud KJ, Inman EM, Hwang B, and Takeyasu K. Analysis of subunit assembly of the Na-K-ATPase. Am J Physiol Cell Physiol 266: C579 –C589, 1994. Fanning AS and Anderson JM. Pdz domains and the formation of protein networks at the plasma membrane. Curr Top Microbiol Immunol 228: 209 –233, 1998. Fanning AS, Jameson BJ, Jesaitis LA, and Anderson JM. The tight junction protein ZO-1 establishes a link between the transmembrane protein occludin and the actin cytoskeleton. J Biol Chem 273: 29745–29753, 1998. Fanning AS, Ma TY, and Anderson JMm. Isolation and functional characterization of the actin binding region in the tight junction protein ZO-1. FASEB J 16: 1835–1837, 2002. Fei K, Yan L, Zhang J, and Sarras MP Jr. Molecular and biological characterization of a zonula occludens-1 homologue in Hydra vulgaris, named HZO-1. Dev Genes Evol 210: 611– 616, 2000. Fernandez-Castelo S, Bolivar JJ, Lopez-Vancell R, Beaty G, and Cereijido M. Ion transport in MDCK cells. In: Tissue Culture of Epithelial Cells. New York: Plenum, 1985, p. 37–50. Feschenko MS, Donnet C, Wetzel RK, Asinovski NK, Jones LR, and Sweadner KJ. Phospholemman, a single-span membrane protein, is an accessory protein of Na,K-ATPase in cerebellum and choroid plexus. J Neurosci 23: 2161–2169, 2003. Fesenko I, Kurth T, Sheth B, Fleming TP, Citi S, and Hausen P. Tight junction biogenesis in the early Xenopus embryo. Mech Dev 96: 51– 65, 2000. Filshie BK and Flower NE. Junctional structures in hydra. J Cell Sci 23: 151–172, 1977. Fischer S, Wobben M, Marti HH, Renz D, and Schaper W. Hypoxia-induced hyperpermeability in brain microvessel endothelial cells involves VEGF-mediated changes in the expression of zonula occludens-1. Microvasc Res 63: 70 – 80, 2002. Fleming T. Biogenesis of intercellular junctions during epithelial differentiation in the mouse preimplantation embryo. Biol Reprod 58: 34 –35, 1998. Fleming TP, Ghassemifar MR, and Sheth B. Junctional complexes in the early mammalian embryo. Semin Reprod Med 18: 185–193, 2000. Fleming TP, Hay M, Javed Q, and Citi S. Localisation of tight junction protein cingulin is temporally and spatially regulated during early mouse development. Development 117: 1135–1144, 1993. Fleming TP, Papenbrock T, Fesenko I, Hausen P, and Sheth B. Assembly of tight junctions during early vertebrate development. Semin Cell Dev Biol 11: 291–299, 2000. Fleming TP, Sheth B, and Fesenko I. Cell adhesion in the preimplantation mammalian embryo and its role in trophectoderm differentiation and blastocyst morphogenesis. Front Biosci 6: D1000 –D1007, 2001. Fleming TP, Sheth B, Thomas F, Fesenko I, and Eckert J. Developmental assembly of the tight junction. In: Tight Junctions, edited by Cereijido M and Anderson JM. Boca Raton, FL: CRC, 2001, p. 285–303. Francis SA, Kelly JM, McCormack J, Rogers RA, Lai J, Schneeberger EE, and Lynch RD. Rapid reduction of MDCK cell cholesterol by methyl-beta-cyclodextrin alters steady state transepithelial electrical resistance. Eur J Cell Biol 78: 473– 484, 1999. Fujita Y, Krause G, Scheffner M, Zechner D, Leddy HE, Behrens J, Sommer T, and Birchmeier W. Hakai, a c-Cbl-like protein, ubiquitinates and induces endocytosis of the E-cadherin complex. Nat Cell Biol 4: 222–231, 2002. Furuse M, Fujimoto K, Sato N, Hirase T, Tsukita S, and Tsukita S. Overexpression of occludin, a tight junction-associated integral membrane protein, induces the formation of intracellular multilamellar bodies bearing tight junction-like structures. J Cell Sci 109: 429 – 435, 1996. Furuse M, Fujita K, Hiiragi T, Fujimoto K, and Tsukita S. Claudin-1 and -2: novel integral membrane proteins localizing at tight junctions with no sequence similarity to occludin. J Cell Biol 141: 1539 –1550, 1998. Physiol Rev • VOL

160. Furuse M, Furuse K, Sasaki H, and Tsukita S. Conversion of zonulae occludentes from tight to leaky strand type by introducing claudin-2 into Madin-Darby canine kidney I cells. J Cell Biol 153: 263–272, 2001. 161. Furuse M, Hata M, Furuse K, Yoshida Y, Haratake A, Sugitani Y, Noda T, Kubo A, and Tsukita S. Claudin-based tight junctions are crucial for the mammalian epidermal barrier: a lesson from claudin-1-deficient mice. J Cell Biol 156: 1099 –1111, 2002. 162. Furuse M, Hirase T, Itoh M, Nagafuchi A, Yonemura S, Tsukita S, and Tsukita S. Occludin: a novel integral membrane protein localizing at tight junctions. J Cell Biol 123: 1777–1788, 1993. 163. Furuse M, Itoh M, Hirase T, Nagafuchi A, Yonemura S, Tsukita S, and Tsukita S. Direct association of occludin with ZO-1 and its possible involvement in the localization of occludin at tight junctions. J Cell Biol 127: 1617–1626, 1994. 164. Furuse M, Sasaki H, Fujimoto K, and Tsukita S. A single gene product, claudin-1 or -2, reconstitutes tight junction strands and recruits occludin in fibroblasts. J Cell Biol 143: 391– 401, 1998. 165. Furuse M, Sasaki H, and Tsukita S. Manner of interaction of heterogeneous claudin species within and between tight junction strands. J Cell Biol 147: 891–903, 1999. 166. Galeotti G. Concerning the EMF which is generated at the surface of animal membranes on contact with different electrolytes. Z Physic Chem 49: 542–552, 1904. 167. Galeotti G. Ricercerche di elettrofisiologia secondo I criteri dell’elettrochimica. Z Allg Physiol 6: 99 –108, 1907. 168. Gallin WJ. Evolution of the “classical” cadherin family of cell adhesion molecules in vertebrates. Mol Biol Evol 15: 1099 –1107, 1998. 169. Gao L, Joberty G, and Macara IG. Assembly of epithelial tight junctions is negatively regulated by Par6. Curr Biol 12: 221–225, 2002. 170. Garrod DR, Merritt AJ, and Nie Z. Desmosomal adhesion: structural basis, molecular mechanism and regulation. Mol Membr Biol 19: 81–94, 2002. 171. Gatto C, McLoud SM, and Kaplan JH. Heterologous expression of Na(⫹)-K(⫹)-ATPase in insect cells: intracellular distribution of pump subunits. Am J Physiol Cell Physiol 281: C982–C992, 2001. 172. Geering K. Posttranslational modifications and intracellular transport of sodium pumps: importance of subunit assembly. Soc Gen Physiol Ser 46: 31– 43, 1991. 173. Geering K. The functional role of the beta-subunit in the maturation and intracellular transport of Na,K-ATPase. FEBS Lett 285: 189 –193, 1991. 174. Geering K. Topogenic motifs in P-type ATPases. J Membr Biol 174: 181–190, 2000. 175. Georges D. Gap and tight junctions in tunicates. Study in conventional and freeze-fracture techniques. Tissue Cell 11: 781–792, 1979. 176. Ghassemifar MR, Eckert JJ, Houghton FD, Picton HM, Leese HJ, and Fleming TP. Gene expression regulating epithelial intercellular junction biogenesis during human blastocyst development in vitro. Mol Hum Reprod 9: 245–252, 2003. 177. Ghassemifar MR, Sheth B, Papenbrock T, Leese HJ, Houghton FD, and Fleming TP. Occludin TM4(⫺): an isoform of the tight junction protein present in primates lacking the fourth transmembrane domain. J Cell Sci 115: 3171–3180, 2002. 178. Gierer A and Meinhardt H. A theory of biological pattern formation. Kybernetik 12: 30 –39, 1972. 179. Glaunsinger BA, Lee SS, Thomas M, Banks L, and Javier R. Interactions of the PDZ-protein MAGI-1 with adenovirus E4-ORF1 and high-risk papillomavirus E6 oncoproteins. Oncogene 19: 5270 – 5280, 2000. 180. Gloor S, Antonicek H, Sweadner KJ, Pagliusi S, Frank R, Moos M, and Schachner M. The adhesion molecule on glia (AMOG) is a homologue of the beta subunit of the Na,K-ATPase. J Cell Biol 110: 165–174, 1990. 181. Gloor SM. Relevance of Na,K-ATPase to local extracellular potassium homeostasis and modulation of synaptic transmission. FEBS Lett 412: 1– 4, 1997. 182. Gonzalez-Mariscal L, Betanzos A, Nava P, and Jaramillo BE. Tight junction proteins. Prog Biophys Mol Biol 81: 1– 44, 2003.

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS 183. Gonzalez-Mariscal L, Chavez DR, and Cereijido M. Effect of temperature on the occluding junctions of monolayers of epithelioid cells (MDCK). J Membr Biol 79: 175–184, 1984. 184. Gonzalez-Mariscal L, Chavez DR, and Cereijido M. Tight junction formation in cultured epithelial cells (MDCK). J Membr Biol 86: 113–125, 1985. 185. Gonzalez-Mariscal L, Chavez DR, Lazaro A, and Cereijido M. Establishment of tight junctions between cells from different animal species and different sealing capacities. J Membr Biol 107: 43–56, 1989. 186. Gonzalez-Mariscal L, Contreras RG, Bolivar JJ, Ponce A, Chavez DR, and Cereijido M. Role of calcium in tight junction formation between epithelial cells. Am J Physiol Cell Physiol 259: C978 –C986, 1990. 187. Gonzalez-Mariscal L, Islas S, Contreras RG, Garcia-Villegas MR, Betanzos A, Vega J, Diaz-Quinonez A, Martin-Orozco N, Ortiz-Navarrete V, Cereijido M, and Valdes J. Molecular characterization of the tight junction protein ZO-1 in MDCK cells. Exp Cell Res 248: 97–109, 1999. 188. Gottardi CJ and Caplan MJ. Delivery of Na⫹, K(⫹)-ATPase in polarized epithelial cells. Science 260: 552–554, 1993. 189. Gottardi CJ and Caplan MJ. Molecular requirements for the cell-surface expression of multisubunit ion-transporting ATPases Identification of protein domains that participate in Na,K-ATPase and H, K-ATPase subunit assembly. J Biol Chem 268: 14342–14347, 1993. 190. Gottardi CJ and Gumbiner BM. Adhesion signaling: how betacatenin interacts with its partners. Curr Biol 11: R792–R794, 2001. 191. Gow A, Southwood CM, Li JS, Pariali M, Riordan GP, Brodie SE, Danias J, Bronstein JM, Kachar B, and Lazzarini RA. CNS myelin and sertoli cell tight junction strands are absent in Osp/ claudin-11 null mice. Cell 99: 649 – 659, 1999. 192. Grebenkamper K and Galla HJ. Translational diffusion measurements of a fluorescent phospholipid between MDCK-I cells support the lipid model of the tight junctions. Chem Phys Lipids 71: 133– 143, 1994. 193. Green CR. A clarification of the two types of invertebrate pleated septate junction. Tissue Cell 13: 173–188, 1981. 194. Green RC and Bergquist PR. Cell membrane specializations in the Porifera. In: Biologie des Spongiaires. Paris: Colloques Internationaux du Centre National de la Recherche Scientific, 1978, p. 153–158. 195. Green RC and Bergquist PR. Phylogenetic relationships within the invertebrata in relation to the structure of septate junctions and the development of /324 occluding junctional types. J Cell Sci 53: 279, 1982. 196. Griepp EB, Dolan WJ, Robbins ES, and Sabatini DD. Participation of plasma membrane proteins in the formation of tight junctions by cultured epithelial cells. J Cell Biol 96: 693–702, 1983. 197. Grimson MJ, Coates JC, Reynolds JP, Shipman M, Blanton RL, and Harwood AJ. Adherens junctions and beta-catenin-mediated cell signalling in a non-metazoan organism. Nature 408: 727– 731, 2000. 198. Grindstaff KK, Yeaman C, Anandasabapathy N, Hsu SC, Rodriguez-Boulan E, Scheller RH, and Nelson WJ. Sec6/8 complex is recruited to cell-cell contacts and specifies transport vesicle delivery to the basal-lateral membrane in epithelial cells. Cell 93: 731–740, 1998. 199. Gumbiner B and Simons K. A functional assay for proteins involved in establishing an epithelial occluding barrier: identification of a uvomorulin-like polypeptide. J Cell Biol 102: 457– 468, 1986. 200. Gumbiner B and Simons K. The role of uvomorulin in the formation of epithelial occluding junctions. Ciba Found Symp 125: 168 –186, 1987. 201. Gumbiner B, Stevenson B, and Grimaldi A. The role of the cell adhesion molecule uvomorulin in the formation and maintenance of the epithelial junctional complex. J Cell Biol 107: 1575–1587, 1988. 202. Gumbiner BM. Cell adhesion: the molecular basis of tissue architecture and morphogenesis. Cell 84: 345–357, 1996. 203. Gumbiner BM. Regulation of cadherin adhesive activity. J Cell Biol 148: 399 – 404, 2000. Physiol Rev • VOL

1255

204. Gundersen D, Orlowski J and Rodriguez-Boulan E. Apical polarity of Na,K-ATPase in retinal pigment epithelium is linked to a reversal of the ankyrin-fodrin submembrane cytoskeleton. J Cell Biol 112: 863– 872, 1991. 205. Hamazaki Y, Itoh M, Sasaki H, Furuse M, and Tsukita S. Multi-PDZ domain protein 1 (MUPP1) is concentrated at tight junctions through its possible interaction with claudin-1 and junctional adhesion molecule. J Biol Chem 277: 455– 461, 2002. 206. Hammerton RW, Krzeminski KA, Mays RW, Ryan TA, Wollner DA, and Nelson WJ. Mechanism for regulating cell surface distribution of Na⫹, K(⫹)-ATPase in polarized epithelial cells. Science 254: 847– 850, 1991. 207. Hardwicke PM and Freytag JW. A proteolipid associated with Na,K-ATPase is not essential for ATPase activity. Biochem Biophys Res Commun 102: 250 –257, 1981. 208. Haskins J, Gu L, Wittchen ES, Hibbard J, and Stevenson BR. ZO-3, a novel member of the MAGUK protein family found at the tight junction, interacts with ZO-1 and occludin. J Cell Biol 141: 199 –208, 1998. 209. Hasler U, Wang X, Crambert G, Beguin P, Jaisser F, Horisberger JD, and Geering K. Role of beta-subunit domains in the assembly, stable expression, intracellular routing, and functional properties of Na,K-ATPase. J Biol Chem 273: 30826 –30835, 1998. 210. Haue L, Pedersen PA, Jorgensen PL, and Hakansson KO. Cloning, expression, purification and crystallization of the N-domain from the alpha(2) subunit of the membrane-spanning Na,KATPase protein. Acta Crystallogr D Biol Crystallogr 59: 1259 –1261, 2003. 211. Herrera FC and Curran PF. The effect of Ca and antidiuretic hormone on Na transport across frog skin. I. Examination of interrelationships between Ca and hormone. J Gen Physiol 46: 999 – 1010, 1963. 212. Hinck L, Nathke IS, Papkoff J, and Nelson WJ. Dynamics of cadherin/catenin complex formation: novel protein interactions and pathways of complex assembly. J Cell Biol 125: 1327–1340, 1994. 213. Horisberger JD, Jaunin P, Reuben MA, Lasater LS, Chow DC, Forte JG, Sachs G, Rossier BC, and Geering K. The H, KATPase beta-subunit can act as a surrogate for the beta-subunit of Na,K-pumps. J Biol Chem 266: 19131–19134, 1991. 214. Horowitz B, Eakle KA, Scheiner-Bobis G, Randolph GR, Chen CY, Hitzeman RA, and Farley RA. Synthesis and assembly of functional mammalian Na,K-ATPase in yeast. J Biol Chem 265: 4189 – 4192, 1990. 215. Howarth AG, Singer KL, and Stevenson BR. Analysis of the distribution and phosphorylation state of ZO-1 in MDCK and nonepithelial cells. J Membr Biol 137: 261–270, 1994. 216. Howe AK, Aplin AE, and Juliano RL. Anchorage-dependent ERK signaling—mechanisms and consequences. Curr Opin Genet Dev 12: 30 –35, 2002. 217. Hu YK and Kaplan JH. Site-directed chemical labeling of extracellular loops in a membrane protein. The topology of the Na,KATPase alpha-subunit. J Biol Chem 275: 19185–19191, 2000. 218. Hua VB, Chang AB, Tchieu JH, Kumar NM, Nielsen PA, and Saier MH Jr. Sequence and phylogenetic analyses of 4 TMS junctional proteins of animals: connexins, innexins, claudins and occludins. J Membr Biol 194: 59 –76, 2003. 219. Huber D, Balda MS, and Matter K. Occludin modulates transepithelial migration of neutrophils. J Biol Chem 275: 5773–5778, 2000. 220. Huber O, Bierkamp C, and Kemler R. Cadherins and catenins in development. Curr Opin Cell Biol 8: 685– 691, 1996. 221. Hudson RL. Ion transport by the isolated mantle epithelium of the freshwater clam, Unio complanatus. Am J Physiol Regul Integr Comp Physiol 263: R76 –R83, 1992. 222. Ide N, Hata Y, Nishioka H, Hirao K, Yao I, Deguchi M, Mizoguchi A, Nishimori H, Tokino T, Nakamura Y, and Takai Y. Localization of membrane-associated guanylate kinase (MAGI)-1/ BAI-associated protein (BAP) 1 at tight junctions of epithelial cells. Oncogene 18: 7810 –7815, 1999. 223. Ikenouchi J, Matsuda M, Furuse M, and Tsukita S. Regulation of tight junctions during the epithelium-mesenchyme transition:

84 • OCTOBER 2004 •

www.prv.org

1256

224.

225.

226.

227.

228.

229.

230.

231.

232.

233.

234. 235.

236.

237. 238.

239.

240.

241.

242.

243.

CEREIJIDO, CONTRERAS, AND SHOSHANI

direct repression of the gene expression of claudins/occludin by Snail. J Cell Sci 116: 1959 –1967, 2003. Islas S, Vega J, Ponce L, and Gonzalez-Mariscal L. Nuclear localization of the tight junction protein ZO-2 in epithelial cells. Exp Cell Res 274: 138 –148, 2002. Itoh M, Furuse M, Morita K, Kubota K, Saitou M, and Tsukita S. Direct binding of three tight junction-associated MAGUKs, ZO-1, ZO-2, and ZO-3, with the COOH termini of claudins. J Cell Biol 147: 1351–1363, 1999. Itoh M, Nagafuchi A, Moroi S, and Tsukita S. Involvement of ZO-1 in cadherin-based cell adhesion through its direct binding to alpha catenin and actin filaments. J Cell Biol 138: 181–192, 1997. Itoh M, Sasaki H, Furuse M, Ozaki H, Kita T, and Tsukita S. Junctional adhesion molecule (JAM) binds to PAR-3: a possible mechanism for the recruitment of PAR-3 to tight junctions. J Cell Biol 154: 491– 497, 2001. Izumi Y, Hirose T, Tamai Y, Hirai S, Nagashima Y, Fujimoto T, Tabuse Y, Kemphues KJ, and Ohno S. An atypical PKC directly associates and colocalizes at the epithelial tight junction with ASIP, a mammalian homologue of Caenorhabditis elegans polarity protein PAR-3. J Cell Biol 143: 95–106, 1998. James PF, Grupp IL, Grupp G, Woo AL, Askew GR, Croyle ML, Walsh RA, and Lingrel JB. Identification of a specific role for the Na,K-ATPase alpha 2 isoform as a regulator of calcium in the heart. Mol Cell 3: 555–563, 1999. Javed Q, Fleming TP, Hay M, and Citi S. Tight junction protein cingulin is expressed by maternal and embryonic genomes during early mouse development. Development 117: 1145–1151, 1993. Jewell EA and Lingrel JB. Comparison of the substrate dependence properties of the rat Na,K-ATPase alpha 1, alpha 2, and alpha 3 isoforms expressed in HeLa cells. J Biol Chem 266: 16925–16930, 1991. Johansson A, Driessens M, and Aspenstrom P. The mammalian homologue of the Caenorhabditis elegans polarity protein PAR-6 is a binding partner for the Rho GTPases Cdc42 and Rac1. J Cell Sci 113: 3267–3275, 2000. Johnson JP, Steele RE, Perkins FM, Wade JB, Preston AS, Green SW, and Handler JS. Epithelial organization and hormone sensitivity of toad urinary bladder cells in culture. Am J Physiol Renal Fluid Electrolyte Physiol 241: F129 –F138, 1981. Jorgensen PL. Aspects of gene structure and functional regulation of the isozymes of Na,K-ATPase. Cell Mol Biol 47: 231–238, 2001. Jungreis AM, Hoges TK, Kleinzeller A, and Schultz SG. Water Relations in Membrane Transport in Plants and Animals. New York: Academic, 1977. Just F and Walz B. Immunocytochemical localization of Na(⫹)/ K(⫹)-ATPase and V-H(⫹)-ATPase in the salivary glands of the cockroach, Periplaneta americana. Cell Tissue Res 278: 161–170, 1994. Kachar B and Reese TS. Evidence for the lipidic nature of tight junction strands. Nature 296: 464 – 466, 1982. Kalt MR. The relationship between cleavage and blastocoel formation in Xenopus laevis. II. Electron microscopic observations. J Embryol Exp Morphol 26: 51– 66, 1971. Kamberov E, Makarova O, Roh M, Liu A, Karnak D, Straight S, and Margolis B. Molecular cloning and characterization of Pals, proteins associated with mLin-7. J Biol Chem 275: 11425–11431, 2000. Kan FW. Cytochemical evidence for the presence of phospholipids in epithelial tight junction strands. J Histochem Cytochem 41: 649 – 656, 1993. Karlish SJ, Goldshleger R, and Jorgensen PL. Location of Asn831 of the alpha chain of Na/K-ATPase at the cytoplasmic surface. Implication for topological models. J Biol Chem 268: 3471– 3478, 1993. Kashgarian M, Biemesderfer D, Caplan M, and Forbush B, III. Monoclonal antibody to Na,K-ATPase: immunocytochemical localization along nephron segments. Kidney Int 28: 899 –913, 1985. Kawabe H, Nakanishi H, Asada M, Fukuhara A, Morimoto K, Takeuchi M, and Takai Y. Pilt, a novel peripheral membrane protein at tight junctions in epithelial cells. J Biol Chem 276: 48350 – 48355, 2001. Physiol Rev • VOL

244. Kawai H, Yasuda H, Terada M, Omatsu-Kanbe M, and Kikkawa R. Axonal contact regulates expression of alpha2 and beta2 isoforms of Na⫹-K⫹-ATPase in Schwann cells: adhesion molecules and nerve regeneration. J Neurochem 69: 330 –339, 1997. 245. Kedem O. Criteria of active transport. In: Membrane Transport and Metabolism. London: Academic, 1961. 246. Kemphues K. PARsing embryonic polarity. Cell 101: 345–348, 2000. 247. Kimura M, Sawada N, Kimura H, Isomura H, Hirata K, and Mori M. Comparison between the distribution of 7H6 tight junction-associated antigen and occludin during the development of chick intestine. Cell Struct Funct 21: 91–96, 1996. 248. King N, Hittinger CT, and Carroll SB. Evolution of key cell signaling and adhesion protein families predates animal origins. Science 301: 361–363, 2003. 249. Kirley TL. Determination of three disulfide bonds and one free sulfhydryl in the beta subunit of (Na,K)-ATPase. J Biol Chem 264: 7185–7192, 1989. 250. Kiuchi-Saishin Y, Gotoh S, Furuse M, Takasuga A, Tano Y, and Tsukita S. Differential expression patterns of claudins, tight junction membrane proteins, in mouse nephron segments. J Am Soc Nephrol 13: 875– 886, 2002. 251. Knudsen KA, Soler AP, Johnson KR, and Wheelock MJ. Interaction of alpha-actinin with the cadherin/catenin cell-cell adhesion complex via alpha-catenin. J Cell Biol 130: 67–77, 1995. 252. Koefoed-Johnsen V and Ussing HH. The nature of the frog skin potential. Acta Physiol Scand 42: 298 –308, 1958. 255. Kojima S, Rahner C, Peng S, and Rizzolo LJ. Claudin 5 is transiently expressed during the development of the retinal pigment epithelium. J Membr Biol 186: 81– 88, 2002. 256. Kollmar R, Nakamura SK, Kappler JA, and Hudspeth AJ. Expression and phylogeny of claudins in vertebrate primordia. Proc Natl Acad Sci USA 98: 10196 –10201, 2001. 257. Korswagen HC, Herman MA, and Clevers HC. Distinct betacatenins mediate adhesion and signalling functions in C. elegans. Nature 406: 527–532, 2000. 258. Kraemer D, Koob R, Friedrichs B, and Drenckhahn D. Two novel peripheral membrane proteins, pasin 1 and pasin 2, associated with Na(⫹), K(⫹)-ATPase in various cells and tissues. J Cell Biol 111: 2375–2383, 1990. 259. Kraemer DM, Strizek B, Meyer HE, Marcus K, and Drenckhahn D. Kidney Na(⫹), K(⫹)-ATPase is associated with moesin. Eur J Cell Biol 82: 87–92, 2003. 260. Kriebel PW, Barr VA, and Parent CA. Adenylyl cyclase localization regulates streaming during chemotaxis. Cell 112: 549 –560, 2003. 261. Krogh A. Osmotic Regulation in Aquatic Animals. Mineola, NY: Dover, 1939. 262. Kubota K, Furuse M, Sasaki H, Sonoda N, Fujita K, Nagafuchi A, and Tsukita S. Ca(2⫹)-independent cell-adhesion activity of claudins, a family of integral membrane proteins localized at tight junctions. Curr Biol 9: 1035–1038, 1999. 263. Kurihara H, Anderson JM, and Farquhar MG. Diversity among tight junctions in rat kidney: glomerular slit diaphragms and endothelial junctions express only one isoform of the tight junction protein ZO-1. Proc Natl Acad Sci USA 89: 7075–7079, 1992. 264. Kuster B, Shainskaya A, Pu HX, Goldshleger R, Blostein R, Mann M, and Karlish SJ. A new variant of the gamma subunit of renal Na,K-ATPase. Identification by mass spectrometry, antibody binding, and expression in cultured cells. J Biol Chem 275: 18441– 18446, 2000. 265. Lacaz-Vieira F, Jaeger MM, Farshori P, and Kachar B. Small synthetic peptides homologous to segments of the first external loop of occludin impair tight junction resealing. J Membr Biol 168: 289 –297, 1999. 266. Lane NJ. Developmental stages in the formation of inverted gap junctions during turnover in the adult horseshoe crab, Limulus. J Cell Sci 32: 293–305, 1978. 267. Lane NJ. Freeze-fracture and tracer studies on the intercellular junctions of insect rectal tissues. Tissue Cell 11: 481–506, 1979. 268. Lane NJ. Tight junctions in a fluid-transporting epithelium of an insect. Science 204: 91–93, 1979.

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS 269. Lane NJ. Tight junctions in invertebrates. In: Tight Junctions, edited by Cereijido M and Anderson JM. Boca Raton, FL: CRC, 2001, p. 39 – 60. 270. Lane NJ and Chandler HJ. Definitive evidence for the existence of tight junctions in invertebrates. J Cell Biol 86: 765–774, 1980. 271. Lane NJ, Skaer HL, and Swales LS. Intercellular junctions in the central nervous system of insects. J Cell Sci 26: 175–199, 1977. 272. Laughery MD, Todd ML, and Kaplan JH. Mutational analysis of alpha-beta subunit interactions in the delivery of Na,K-ATPase heterodimers to the plasma membrane. J Biol Chem 278: 34794 – 34803, 2003. 273. Le Bivic A, Sambuy Y, Mostov K, and Rodriguez-Boulan E. Vectorial targeting of an endogenous apical membrane sialoglycoprotein and uvomorulin in MDCK cells. J Cell Biol 110: 1533–1539, 1990. 274. Lee JK, Brandin E, Branton D, and Goldstein LS. alpha-Spectrin is required for ovarian follicle monolayer integrity in Drosophila melanogaster. Development 124: 353–362, 1997. 275. Lee JK, Coyne RS, Dubreuil RR, Goldstein LS, and Branton D. Cell shape and interaction defects in alpha-spectrin mutants of Drosophila melanogaster. J Cell Biol 123: 1797–1809, 1993. 276. Leighton J, Brada Z, Estes LW, and Justh G. Secretory activity and oncogenicity of a cell line (MDCK) derived from canine kidney. Science 163: 472– 473, 1969. 277. Lemas MV, Hamrick M, Takeyasu K, and Fambrough DM. 26 amino acids of an extracellular domain of the Na,K-ATPase alphasubunit are sufficient for assembly with the Na,K-ATPase betasubunit. J Biol Chem 269: 8255– 8259, 1994. 278. Leung CL, Green KJ, and Liem RK. Plakins: a family of versatile cytolinker proteins. Trends Cell Biol 12: 37– 45, 2002. 279. Leung LW, Contreras RG, Flores-Maldonado C, Cereijido M, and Rodriguez-Boulan E. Inhibitors of glycosphingolipid biosynthesis reduce transepithelial electrical resistance in MDCK I and FRT cells. Am J Physiol Cell Physiol 284: C1021–C1030, 2003. 280. Lever JE. Inducers of mammalian cell differentiation stimulate dome formation in a differentiated kidney epithelial cell line (MDCK). Proc Natl Acad Sci USA 76: 1323–1327, 1979. 281. Lin D, Edwards AS, Fawcett JP, Mbamalu G, Scott JD, and Pawson T. A mammalian PAR-3-PAR-6 complex implicated in Cdc42/Rac1 and aPKC signalling and cell polarity. Nat Cell Biol 2: 540 –547, 2000. 282. Lingrel J, Moseley A, Dostanic I, Cougnon M, He S, James P, Woo A, O’connor K, and Neumann J. Functional roles of the alpha isoforms of the Na,K-ATPase. Ann NY Acad Sci 986: 354 –359, 2003. 283. Lisanti MP, Caras IW, Davitz MA, and Rodriguez-Boulan E. A glycophospholipid membrane anchor acts as an apical targeting signal in polarized epithelial cells. J Cell Biol 109: 2145–2156, 1989. 284. Lisanti MP, Sargiacomo M, Graeve L, Saltiel AR, and Rodriguez-Boulan E. Polarized apical distribution of glycosyl-phosphatidylinositol-anchored proteins in a renal epithelial cell line. Proc Natl Acad Sci USA 85: 9557–9561, 1988. 285. Lorber V and Rayns DG. Cellular junctions in the tunicate heart. J Cell Sci 10: 211–227, 1972. 286. Louvard D. Apical membrane aminopeptidase appears at site of cell-cell contact in cultured kidney epithelial cells. Proc Natl Acad Sci USA 77: 4132– 4136, 1980. 287. Lynch RD, Tkachuk LJ, Ji X, Rabito CA, and Schneeberger EE. Depleting cell cholesterol alters calcium-induced assembly of tight junctions by monolayers of MDCK cells. Eur J Cell Biol 60: 21–30, 1993. 288. Madin SH and Darby NB. American Type Culture Collection Catalog of Strains. Manassas, VA: ATCC, 1958, p. 574. 289. Mahmmoud YA, Vorum H, and Cornelius F. Identification of a phospholemman-like protein from shark rectal glands. Evidence for indirect regulation of Na,K-ATPase by protein kinase c via a novel member of the FXYDY family. J Biol Chem 275: 35969 –35977, 2000. 290. Makagiansar IT, Avery M, Hu Y, Audus KL, and Siahaan TJ. Improving the selectivity of HAV-peptides in modulating E-cadherin-E-cadherin interactions in the intercellular junction of MDCK cell monolayers. Pharm Res 18: 446 – 453, 2001. Physiol Rev • VOL

1257

291. Malik N, Canfield VA, Beckers MC, Gros P, and Levenson R. Identification of the mammalian Na,K-ATPase 3 subunit. J Biol Chem 271: 22754 –22758, 1996. 292. Mandai K, Nakanishi H, Satoh A, Obaishi H, Wada M, Nishioka H, Itoh M, Mizoguchi A, Aoki T, Fujimoto T, Matsuda Y, Tsukita S, and Takai Y. Afadin: a novel actin filament-binding protein with one PDZ domain localized at cadherin-based cell-tocell adherens junction. J Cell Biol 139: 517–528, 1997. 293. Marie H, Pratt SJ, Betson M, Epple H, Kittler JT, Meek L, Moss SJ, Troyanovsky S, Attwell D, Longmore GD, and Braga VM. The LIM protein Ajuba is recruited to cadherin-dependent cell junctions through an association with alpha-catenin. J Biol Chem 278: 1220 –1228, 2003. 294. Mariner DJ, Wang J, and Reynolds AB. Arvcf localizes to the nucleus and adherens junction and is mutually exclusive with p120(ctn) in E-cadherin complexes. J Cell Sci 113: 1481–1490, 2000. 295. Martin-Padura I, Lostaglio S, Schneemann M, Williams L, Romano M, Fruscella P, Panzeri C, Stoppacciaro A, Ruco L, Villa A, Simmons D, and Dejana E. Junctional adhesion molecule, a novel member of the immunoglobulin superfamily that distributes at intercellular junctions and modulates monocyte transmigration. J Cell Biol 142: 117–127, 1998. 296. Martin-Vasallo P, Dackowski W, Emanuel JR, and Levenson R. Identification of a putative isoform of the Na,K-ATPase beta subunit. Primary structure and tissue-specific expression. J Biol Chem 264: 4613– 4618, 1989. 297. Martinez-Palomo A, Meza I, Beaty G, and Cereijido M. Experimental modulation of occluding junctions in a cultured transporting epithelium. J Cell Biol 87: 736 –745, 1980. 298. Marzesco AM, Galli T, Louvard D, and Zahraoui A. The rod cGMP phosphodiesterase delta subunit dissociates the small GTPase Rab13 from membranes. J Biol Chem 273: 22340–22345, 1998. 299. Matter K and Balda MS. Biogenesis of tight junctions: the Cterminal domain of occludin mediates basolateral targeting. J Cell Sci 111: 511–519, 1998. 300. Matter K and Balda MS. Occludin and the functions of tight junctions. Int Rev Cytol 186: 117–146, 1999. 301. Matter K and Balda MS. Signalling to and from tight junctions. Nat Rev Mol Cell Biol 4: 225–236, 2003. 302. Matter K and Mellman I. Mechanisms of cell polarity: sorting and transport in epithelial cells. Curr Opin Cell Biol 6: 545–554, 1994. 303. Mauchamp J, Chambard M, Gabrion J, and Verrier B. Polarized multicellular structures designed for the in vitro study of thyroid cell function and polarization. Methods Enzymol 98: 477– 486, 1983. 304. McCarthy KM, Skare IB, Stankewich MC, Furuse M, Tsukita S, Rogers RA, Lynch RD, and Schneeberger EE. Occludin is a functional component of the tight junction. J Cell Sci 109: 2287– 2298, 1996. 305. McCrea PS, Brieher WM, and Gumbiner BM. Induction of a secondary body axis in Xenopus by antibodies to beta-catenin. J Cell Biol 123: 477– 484, 1993. 306. McGrail KM, Phillips JM, and Sweadner KJ. Immunofluorescent localization of three Na,K-ATPase isozymes in the rat central nervous system: both neurons and glia can express more than one Na,K-ATPase. J Neurosci 11: 381–391, 1991. 307. McNeill H, Ozawa M, Kemler R, and Nelson WJ. Novel function of the cell-adhesion molecule uvomorulin as an inducer of cellsurface polarity. Cell 62: 309 –316, 1990. 308. McNutt NS. A thin-section and freeze-fracture study of microfilament-membrane attachments in choroid plexus and intestinal microvilli. J Cell Biol 79: 774 –787, 1978. 309. Medina R, Rahner C, Mitic LL, Anderson JM, and Van Itallie CM. Occludin localization at the tight junction requires the second extracellular loop. J Membr Biol 178: 235–247, 2000. 310. Merzdorf CS, Chen YH, and Goodenough DA. Formation of functional tight junctions in Xenopus embryos. Dev Biol 195: 187– 203, 1998. 311. Meza I, Ibarra G, Sabanero M, Martinez-Palomo A, and Cereijido M. Occluding junctions and cytoskeletal components in a cultured transporting epithelium. J Cell Biol 87: 746 –754, 1980.

84 • OCTOBER 2004 •

www.prv.org

1258

CEREIJIDO, CONTRERAS, AND SHOSHANI

312. Meza I, Sabanero M, Stefani E, and Cereijido M. Occluding junctions in MDCK cells: modulation of transepithelial permeability by the cytoskeleton. J Cell Biochem 18: 407– 421, 1982. 313. Mino A, Ohtsuka T, Inoue E, and Takai Y. Membrane-associated guanylate kinase with inverted orientation (MAGI)-1/brain angiogenesis inhibitor 1-associated protein (BAP1) as a scaffolding molecule for Rap small G protein GDP/GTP exchange protein at tight junctions. Genes Cells 5: 1009 –1016, 2000. 314. Miranda KC, Khromykh T, Christy P, Le TL, Gottardi CJ, Yap AS, Stow JL, and Teasdale RD. A dileucine motif targets Ecadherin to the basolateral cell surface in Madin-Darby canine kidney and LLC-PK1 epithelial cells. J Biol Chem 276: 22565–22572, 2001. 315. Misfeldt DS, Hamamoto ST, and Pitelka DR. Transepithelial transport in cell culture. Proc Natl Acad Sci USA 73: 1212–1216, 1976. 316. Mogensen MM, Tucker JB, Mackie JB, Prescott AR, and Nathke IS. The adenomatous polyposis coli protein unambiguously localizes to microtubule plus ends and is involved in establishing parallel arrays of microtubule bundles in highly polarized epithelial cells. J Cell Biol 157: 1041–1048, 2002. 317. Moreno J, Cruz-Vera LR, Garcia-Villegas MR, and Cereijido M. Polarized expression of Shaker channels in epithelial cells. J Membr Biol 190: 175–187, 2002. 318. Moreno JH, Reisin IL, Rodriguez-Boulan E, Rotunno CA, and Cereijido M. Barriers to sodium movement across frog skin. J Membr Biol 11: 99 –115, 1973. 319. Morita K, Sasaki H, Fujimoto K, Furuse M, and Tsukita S. Claudin-11/OSP-based tight junctions of myelin sheaths in brain and Sertoli cells in testis. J Cell Biol 145: 579 –588, 1999. 320. Morita K, Sasaki H, Furuse M, and Tsukita S. Endothelial claudin: claudin-5/TMVCF constitutes tight junction strands in endothelial cells. J Cell Biol 147: 185–194, 1999. 321. Moseley AE, Lieske SP, Wetzel RK, James PF, He S, Shelly DA, Paul RJ, Boivin GP, Witte DP, Ramirez JM, Sweadner KJ, and Lingrel JB. The Na,K-ATPase alpha 2 isoform is expressed in neurons, and its absence disrupts neuronal activity in newborn mice. J Biol Chem 278: 5317–5324, 2003. 322. Muller WE. Review: how was metazoan threshold crossed? The hypothetical Urmetazoa. Comp Biochem Physiol A Mol Integr Physiol 129: 433– 460, 2001. 323. Muller WE, Schroder HC, Skorokhod A, Bunz C, Muller IM, and Grebenjuk VA. Contribution of sponge genes to unravel the genome of the hypothetical ancestor of Metazoa (Urmetazoa). Gene 276: 161–173, 2001. 324. Muresan Z, Paul DL, and Goodenough DA. Occludin 1B, a variant of the tight junction protein occludin. Mol Biol Cell 11: 627– 634, 2000. 325. Nakamura T, Blechman J, Tada S, Rozovskaia T, Itoyama T, Bullrich F, Mazo A, Croce CM, Geiger B, and Canaani E. huASH1 protein, a putative transcription factor encoded by a human homologue of the Drosophila ash1 gene, localizes to both nuclei and cell-cell tight junctions. Proc Natl Acad Sci USA 97: 7284 –7289, 2000. 326. Nichols GE, Borgman CA, and Young WW Jr. On tight junction structure: Forssman glycolipid does not flow between MDCK cells in an intact epithelial monolayer. Biochem Biophys Res Commun 138: 1163–1169, 1986. 327. Nigam SK, Rodriguez-Boulan E, and Silver RB. Changes in intracellular calcium during the development of epithelial polarity and junctions. Proc Natl Acad Sci USA 89: 6162– 6166, 1992. 328. Nishimura M, Kakizaki M, Ono Y, Morimoto K, Takeuchi M, Inoue Y, Imai T, and Takai Y. Jeap, a novel component of tight junctions in exocrine cells. J Biol Chem 277: 5583–5587, 2002. 329. Nitta T, Hata M, Gotoh S, Seo Y, Sasaki H, Hashimoto N, Furuse M, and Tsukita S. Size-selective loosening of the bloodbrain barrier in claudin-5-deficient mice. J Cell Biol 161: 653– 660, 2003. 330. Noe V, Willems J, Vandekerckhove J, Roy FV, Bruyneel E, and Mareel M. Inhibition of adhesion and induction of epithelial cell invasion by HAV-containing E-cadherin-specific peptides. J Cell Sci 112: 127–135, 1999. Physiol Rev • VOL

331. Noirot-Timothee C, Smith DS, Cayer ML, and Noirot C. Septate junctions in insects: comparison between intercellular and intramembranous structures. Tissue Cell 10: 125–136, 1978. 332. Nollet F, Kools P, and Van Roy F. Phylogenetic analysis of the cadherin superfamily allows identification of six major subfamilies besides several solitary members. J Mol Biol 299: 551–572, 2000. 333. Nose A, Tsuji K, and Takeichi M. Localization of specificity determining sites in cadherin cell adhesion molecules. Cell 61: 147–155, 1990. 334. Nusrat A, Parkos CA, Verkade P, Foley CS, Liang TW, InnisWhitehouse W, Eastburn KK, and Madara JL. Tight junctions are membrane microdomains. J Cell Sci 113: 1771–1781, 2000. 335. Ochieng J, Warfield P, Green-Jarvis B, and Fentie I. Galectin-3 regulates the adhesive interaction between breast carcinoma cells and elastin. J Cell Biochem 75: 505–514, 1999. 336. Oda H, Wada H, Tagawa K, Akiyama-Oda Y, Satoh N, Humphreys T, Zhang S, and Tsukita S. A novel amphioxus cadherin that localizes to epithelial adherens junctions has an unusual domain organization with implications for chordate phylogeny. Evol Dev 4: 426 – 434, 2002. 337. Ohno S. Intercellular junctions and cellular polarity: the PARaPKC complex, a conserved core cassette playing fundamental roles in cell polarity. Curr Opin Cell Biol 13: 641– 648, 2001. 338. Okamura H, Denawa M, Ohniwa R, and Takeyasu K. P-type ATPase superfamily: evidence for critical roles for kingdom evolution. Ann NY Acad Sci 986: 219 –223, 2003. 339. Okamura H, Yasuhara JC, Fambrough DM, and Takeyasu K. P-type ATPases in Caenorhabditis and Drosophila: implications for evolution of the P-type ATPase subunit families with special reference to the Na,K-ATPase and H, K-ATPase subgroup. J Membr Biol 191: 13–24, 2003. 340. Onsager L. Reciprocal relations in irreversible processes I. Physiol Rev 37: 405– 426, 1931. 341. Onsager L. Reciprocal relations in irreversible processes II. Physiol Rev 38: 2265–2279, 1931. 342. Orlowski J and Lingrel JB. Thyroid and glucocorticoid hormones regulate the expression of multiple Na,K-ATPase genes in cultured neonatal rat cardiac myocytes. J Biol Chem 265: 3462– 3470, 1990. 343. Oxender DL and Christensen HN. Transcellular concentration as a consequence of intracellular accumulation. J Biol Chem 234: 2321–2324, 1959. 344. Ozawa M, Baribault H, and Kemler R. The cytoplasmic domain of the cell adhesion molecule uvomorulin associates with three independent proteins structurally related in different species. EMBO J 8: 1711–1717, 1989. 345. Patrie KM, Drescher AJ, Goyal M, Wiggins RC, and Margolis B. The membrane-associated guanylate kinase protein MAGI-1 binds megalin and is present in glomerular podocytes. J Am Soc Nephrol 12: 667– 677, 2001. 346. Pchejetski D, Taurin S, Der SS, Lopina OD, Pshezhetsky AV, Tremblay J, Deblois D, Hamet P, and Orlov SN. Inhibition of Na⫹-K⫹-ATPase by ouabain triggers epithelial cell death independently of inversion of the [Na⫹]i/[K⫹]i ratio. Biochem Biophys Res Commun 301: 735–744, 2003. 347. Pedersen PL and Carafoli E. Ion motive ATPases. I. Ubiquity, properties and significance to cell function. Trends Biochem Sci 12: 146 –150, 1987. 348. Pedersen PL and Carafoli E. Ion motive ATPases: energy coupling and work output. Trends Biochem Sci 12: 186 –189, 1987. 349. Peifer M, Rauskolb C, Williams M, Riggleman B, and Wieschaus E. The segment polarity gene armadillo interacts with the wingless signaling pathway in both embryonic and adult pattern formation. Development 111: 1029 –1043, 1991. 350. Peinado H, Quintanilla M, and Cano A. Transforming growth factor beta-1 induces snail transcription factor in epithelial cell lines: mechanisms for epithelial mesenchymal transitions. J Biol Chem 278: 21113–21123, 2003. 351. Pelletier TM. The tight junctions in the testis, epididymis, and vas deferens. In: Tight Junctions, edited by Cereijido M. Boca Raton, FL: CRC, 2001, p. 599 – 628. 352. Perez-Moreno M, Avila A, Islas S, Sanchez S, and GonzalezMariscal L. Vinculin but not alpha-actinin is a target of PKC

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

353.

354.

355.

356.

357.

358. 359.

360. 361.

362. 363.

364.

365. 366.

367.

368.

369.

370.

371.

372.

373.

374.

phosphorylation during junctional assembly induced by calcium. J Cell Sci 111: 3563–3571, 1998. Perez-Moreno M, Jamora C, and Fuchs E. Sticky business: orchestrating cellular signals at adherens junctions. Cell 112: 535– 548, 2003. Perez-Moreno MA, Locascio A, Rodrigo I, Dhondt G, Portillo F, Nieto MA, and Cano A. A new role for E12/E47 in the repression of E-cadherin expression and epithelial-mesenchymal transitions. J Biol Chem 276: 27424 –27431, 2001. Pestov NB, Adams G, Shakhparonov MI, and Modyanov NN. Identification of a novel gene of the X,K-ATPase beta-subunit family that is predominantly expressed in skeletal and heart muscles. FEBS Lett 456: 243–248, 1999. Pestov NB, Korneenko TV, Zhao H, Adams G, Kostina MB, Shakhparonov MI, and Modyanov NN. The betam protein, a member of the X, K-ATPase beta-subunits family, is located intracellularly in pig skeletal muscle. Arch Biochem Biophys 396: 80 – 88, 2001. Pestov NB, Korneenko TV, Zhao H, Adams G, Shakhparonov MI, and Modyanov NN. Immunochemical demonstration of a novel beta-subunit isoform of X,K-ATPase in human skeletal muscle. Biochem Biophys Res Commun 277: 430 – 435, 2000. Pinto DS and Kachar B. On tight-junction structure. Cell 28: 441– 450, 1982. Ponce A, Bolivar JJ, Vega J, and Cereijido M. Synthesis of plasma membrane and potassium channels in epithelia. Cell Physiol Biochem 1: 195–204, 1991. Ponce A and Cereijido M. Polarized distribution of cation channels in epithelial cells. Cell Physiol Biochem 1: 13–23, 1991. Ponce A, Contreras RG, and Cereijido M. Polarized distribution of chloride channels in epithelial cells (MDCK). Cell Physiol Biochem 1: 160 –169, 1991. Pouliot Y. Phylogenetic analysis of the cadherin superfamily. Bioessays 14: 743–748, 1992. Prasad R, Gu Y, Alder H, Nakamura T, Canaani O, Saito H, Huebner K, Gale RP, Nowell PC, and Kuriyama K. Cloning of the ALL-1 fusion partner, the AF-6 gene, involved in acute myeloid leukemias with the t(6;11) chromosome translocation. Cancer Res 53: 5624 –5628, 1993. Prozialeck WC and Lamar PC. Interaction of cadmium (Cd2⫹) with a 13-residue polypeptide analog of a putative calcium-binding motif of E-cadherin. Biochim Biophys Acta 1451: 93–100, 1999. Prusch R and Otter T. Annelid transepithelial ion transport. Comp Biochem Physiol A Physiol 57: 87–92, 1977. Pu HX, Cluzeaud F, Goldshleger R, Karlish SJ, Farman N, and Blostein R. Functional role and immunocytochemical localization of the gamma a and gamma b forms of the Na,K-ATPase gamma subunit. J Biol Chem 276: 20370 –20378, 2001. Rabito CA, Boulan ER, and Cereijido M. Effect of the composition of the inner bathing solution on transport properties of the frog skin. Biochim Biophys Acta 311: 630 – 639, 1973. Rabito CA and Karish MV. Polarized amino acid transport by an epithelial cell line of renal origin (LLC-PK1). The apical systems. J Biol Chem 258: 2543–2547, 1983. Rabito CA, Rotunno CA, and Cereijido M. Amiloride and calcium effect on the outer barrier of the frog skin. J Membr Biol 42: 169 –187, 1978. Rabito CA and Tchao R. [3H]ouabain binding during the monolayer organization and cell cycle in MDCK cells. Am J Physiol Cell Physiol 238: C43–C48, 1980. Rabito CA, Tchao R, Valentich J, and Leighton J. Effect of cell-substratum interaction on hemicyst formation by MDCK cells. In Vitro 16: 461– 468, 1980. Renaud-Young M and Gallin WJ. In the first extracellular domain of E-cadherin, heterophilic interactions, but not the conserved His-Ala-Val motif, are required for adhesion. J Biol Chem 277: 39609 –39616, 2002. Reuss L. Transport in gallbladder. In: Membrane Transport in Biology, edited by Giebisch G. New York: Springer-Verlag, 1979, vol. IVB. Reuss L. Epithelial transport. In: Handbook of Physiology. Cell Physiology. Bethesda, MD: Am. Physiol. Soc., 1997, sect. 14. Physiol Rev • VOL

1259

375. Reyes JL, Lamas M, Martin D, Del Carmen NM, Islas S, Luna J, Tauc M, and Gonzalez-Mariscal L. The renal segmental distribution of claudins changes with development. Kidney Int 62: 476 – 487, 2002. 376. Rindler MJ, Ivanov IE, Plesken H, Rodriguez-Boulan E, and Sabatini DD. Viral glycoproteins destined for apical or basolateral plasma membrane domains traverse the same Golgi apparatus during their intracellular transport in doubly infected Madin-Darby canine kidney cells. J Cell Biol 98: 1304 –1319, 1984. 377. Rizzolo LJ and Zhou S. The distribution of Na⫹-K⫹-ATPase and 5A11 antigen in apical microvilli of the retinal pigment epithelium is unrelated to alpha-spectrin. J Cell Sci 108: 3623–3633, 1995. 378. Rodriguez-Boulan E and Nelson WJ. Morphogenesis of the polarized epithelial cell phenotype. Science 245: 718 –725, 1989. 379. Rodriguez-Boulan E, Paskiet KT, and Sabatini DD. Assembly of enveloped viruses in Madin-Darby canine kidney cells: polarized budding from single attached cells and from clusters of cells in suspension. J Cell Biol 96: 866 – 874, 1983. 380. Rodriguez-Boulan E, Paskiet KT, Salas PJ, and Bard E. Intracellular transport of influenza virus hemagglutinin to the apical surface of Madin-Darby canine kidney cells. J Cell Biol 98: 308 –319, 1984. 381. Rodriguez-Boulan E and Pendergast M. Polarized distribution of viral envelope proteins in the plasma membrane of infected epithelial cells. Cell 20: 45–54, 1980. 382. Rodriguez-Boulan E and Sabatini DD. Asymmetric budding of viruses in epithelial monolayers: a model system for study of epithelial polarity. Proc Natl Acad Sci USA 75: 5071–5075, 1978. 383. Roh MH, Liu CJ, Laurinec S, and Margolis B. The carboxyl terminus of zona occludens-3 binds and recruits a mammalian homologue of discs lost to tight junctions. J Biol Chem 277: 27501– 27509, 2002. 384. Roh MH, Makarova O, Liu CJ, Shin K, Lee S, Laurinec S, Goyal M, Wiggins R, and Margolis B. The Maguk protein, Pals1, functions as an adapter, linking mammalian homologues of Crumbs and Discs Lost. J Cell Biol 157: 161–172, 2002. 385. Rose AM and Valdes R Jr. Understanding the sodium pump and its relevance to disease. Clin Chem 40: 1674 –1685, 1994. 386. Rotunno CA, Kowalewski V, and Cereijido M. Nuclear spin resonance evidence for complexing of sodium in frog skin. Biochim Biophys Acta 135: 170 –173, 1967. 387. Rotunno CA, Zylber EA, and Cereijido M. Ion and water balance in the epithelium of the abdominal skin of the frog Leptodactylus ocellatus. J Membr Biol 13: 217–232, 1973. 388. Runnegar B. Collagen gene construction and evolution. J Mol Evol 22: 141–149, 1985. 389. Saha C, Nigam SK, and Denker BM. Involvement of Galphai2 in the maintenance and biogenesis of epithelial cell tight junctions. J Biol Chem 273: 21629 –21633, 1998. 390. Saha C, Nigam SK, and Denker BM. Expanding role of G proteins in tight junction regulation: Galpha(s) stimulates TJ assembly. Biochem Biophys Res Commun 285: 250 –256, 2001. 391. Saitou M, Ando-Akatsuka Y, Itoh M, Furuse M, Inazawa J, Fujimoto K, and Tsukita S. Mammalian occludin in epithelial cells: its expression and subcellular distribution. Eur J Cell Biol 73: 222–231, 1997. 392. Saitou M, Fujimoto K, Doi Y, Itoh M, Fujimoto T, Furuse M, Takano H, Noda T, and Tsukita S. Occludin-deficient embryonic stem cells can differentiate into polarized epithelial cells bearing tight junctions. J Cell Biol 141: 397– 408, 1998. 393. Saitou M, Furuse M, Sasaki H, Schulzke JD, Fromm M, Takano H, Noda T, and Tsukita S. Complex phenotype of mice lacking occludin, a component of tight junction strands. Mol Biol Cell 11: 4131– 4142, 2000. 394. Sakakibara A, Furuse M, Saitou M, Ando-Akatsuka Y, and Tsukita S. Possible involvement of phosphorylation of occludin in tight junction formation. J Cell Biol 137: 1393–1401, 1997. 395. Salas PJ, Vega-Salas DE, and Rodriguez-Boulan E. Collagen receptors mediate early events in the attachment of epithelial (MDCK) cells. J Membr Biol 98: 223–236, 1987. 396. Sarvazyan NA, Modyanov NN, and Askari A. Intersubunit and intrasubunit contact regions of Na⫹/K⫹-ATPase revealed by con-

84 • OCTOBER 2004 •

www.prv.org

1260

397.

398.

399.

400.

401.

402.

403. 404.

405.

406.

407.

408.

409.

410.

411.

412.

413.

414.

415.

416.

CEREIJIDO, CONTRERAS, AND SHOSHANI

trolled proteolysis and chemical cross-linking. J Biol Chem 270: 26528 –26532, 1995. Schatzmann HJ. Cardiac glycosides as inhibitors of active potassium and sodium transport by erythrocyte membrane. Helv Physiol Pharmacol Acta 11: 346 –354, 1953. Schmalzing G, Eckard P, Kroner S, and Passow H. Downregulation of surface sodium pumps by endocytosis during meiotic maturation of Xenopus laevis oocytes. Am J Physiol Cell Physiol 258: C179 –C184, 1990. Schmalzing G, Kroner S, Schachner M, and Gloor S. The adhesion molecule on glia (AMOG/beta 2) and alpha 1 subunits assemble to functional sodium pumps in Xenopus oocytes. J Biol Chem 267: 20212–20216, 1992. Schmalzing G, Ruhl K, and Gloor SM. Isoform-specific interactions of Na,K-ATPase subunits are mediated via extracellular domains and carbohydrates. Proc Natl Acad Sci USA 94: 1136 –1141, 1997. Schneeberger EE, Lynch RD, Kelly CA, and Rabito CA. Modulation of tight junction formation in clone 4 MDCK cells by fatty acid supplementation. Am J Physiol Cell Physiol 254: C432–C440, 1988. Schneider JW, Mercer RW, Gilmore-Hebert M, Utset MF, Lai C, Greene A, and Benz EJ Jr. Tissue specificity, localization in brain, and cell-free translation of mRNA encoding the A3 isoform of Na⫹-K⫹-ATPase. Proc Natl Acad Sci USA 85: 284 –288, 1988. Schoner W. Endogenous cardiac glycosides, a new class of steroid hormones. Eur J Biochem 269: 2440 –2448, 2002. Schram FR. The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge, MA: Cambridge Univ. Press, 1991. Schultz SG and Curran PF. The role of sodium in non-electrolyte transport across animal cell membranes. Physiologist 12: 437– 452, 1969. Shamraj OI and Lingrel JB. A putative fourth Na⫹, K(⫹)-ATPase alpha-subunit gene is expressed in testis. Proc Natl Acad Sci USA 91: 12952–12956, 1994. Shapiro L, Fannon AM, Kwong PD, Thompson A, Lehmann MS, Grubel G, Legrand JF, Als-Nielsen J, Colman DR, and Hendrickson WA. Structural basis of cell-cell adhesion by cadherins. Nature 374: 327–337, 1995. Sheth B, Fesenko I, Collins JE, Moran B, Wild AE, Anderson JM, and Fleming TP. Tight junction assembly during mouse blastocyst formation is regulated by late expression of ZO-1 alpha⫹ isoform. Development 124: 2027–2037, 1997. Sheth B, Fontaine JJ, Ponza E, McCallum A, Page A, Citi S, Louvard D, Zahraoui A, and Fleming TP. Differentiation of the epithelial apical junctional complex during mouse preimplantation development: a role for rab13 in the early maturation of the tight junction. Mech Dev 97: 93–104, 2000. Sheth B, Moran B, Anderson JM, and Fleming TP. Post-translational control of occludin membrane assembly in mouse trophectoderm: a mechanism to regulate timing of tight junction biogenesis and blastocyst formation. Development 127: 831– 840, 2000. Shoshani L and Contreras RG. Biogenesis of epithelial polarity and tight junctions. In: Tight Junctions, edited by Cereijido M. Boca Raton, FL: CRC, 2001, p. 165–197. Shull GE, Greeb J, and Lingrel JB. Molecular cloning of three distinct forms of the Na⫹-K⫹-ATPase alpha-subunit from rat brain. Biochemistry 25: 8125– 8132, 1986. Shull GE, Schwartz A, and Lingrel JB. Amino-acid sequence of the catalytic subunit of the (Na⫹ ⫹ K⫹)ATPase deduced from a complementary DNA. Nature 316: 691– 695, 1985. Simon DB, Lu Y, Choate KA, Velazquez H, Al Sabban E, Praga M, Casari G, Bettinelli A, Colussi G, Rodriguez-Soriano J, Mccredie D, Milford D, Sanjad S, and Lifton RP. Paracellin-1, a renal tight junction protein required for paracellular Mg2⫹ resorption. Science 285: 103–106, 1999. Simske JS, Koppen M, Sims P, Hodgkin J, Yonkof A, and Hardin J. The cell junction protein VAB-9 regulates adhesion and epidermal morphology in C. elegans. Nat Cell Biol 5: 619 – 625, 2003. Sinaga E, Jois SD, Avery M, Makagiansar IT, Tambunan US, Audus KL, and Siahaan TJ. Increasing paracellular porosity by Physiol Rev • VOL

417.

418.

419.

420. 421. 422.

423.

424.

425.

426.

427.

428.

429.

430.

431.

432. 433.

434. 435. 436.

437.

438.

E-cadherin peptides: discovery of bulge and groove regions in the EC1-domain of E-cadherin. Pharm Res 19: 1170 –1179, 2002. Skou JC. Further investigations on a Mg⫹⫹⫹Na⫹-activated adenosinetriphosphatase, possibly related to the active, linked transport of Na⫹ and K⫹ across the nerve membrane. Biochim Biophys Acta 42: 6 –23, 1960. Skou JC. The influence of some cations on an adenosine triphosphatase from peripheral nerves. Biochim Biophys Acta 23: 394 – 401, 1957. Spiegel S, Blumenthal R, Fishman PH, and Handler JS. Gangliosides do not move from apical to basolateral plasma membrane in cultured epithelial cells. Biochim Biophys Acta 821: 310 –318, 1985. Staehelin LA. Structure and function of intercellular junctions. Int Rev Cytol 39: 191–283, 1974. Stefani E and Cereijido M. Electrical properties of cultured epithelioid cells (MDCK). J Membr Biol 73: 177–184, 1983. Steinberg RH and Miller SS. Transport and membrane properties of the retinal pigment epithelium. In: The Retinal Pigment Epithelium, edited by Zinn KM and Marmor MF. Cambridge, MA: Harvard Univ. Press, 1979, p. 205–225. Stetler-Stevenson WG, Aznavoorian S, and Liotta LA. Tumor cell interactions with the extracellular matrix during invasion and metastasis. Annu Rev Cell Biol 9: 541–573, 1993. Stevenson BR, Anderson JM, Braun ID, and Mooseker MS. Phosphorylation of the tight-junction protein ZO-1 in two strains of Madin-Darby canine kidney cells which differ in transepithelial resistance. Biochem J 263: 597–599, 1989. Stevenson BR, Siliciano JD, Mooseker MS, and Goodenough DA. Identification of ZO-1: a high molecular weight polypeptide associated with the tight junction (zonula occludens) in a variety of epithelia. J Cell Biol 103: 755–766, 1986. Sunshine C, Francis S, and Kirk KL. Rab3B regulates ZO-1 targeting and actin organization in PC12 neuroendocrine cells. Exp Cell Res 257: 1–10, 2000. Suzuki A, Yamanaka T, Hirose T, Manabe N, Mizuno K, Shimizu M, Akimoto K, Izumi Y, Ohnishi T, and Ohno S. Atypical protein kinase C is involved in the evolutionarily conserved par protein complex and plays a critical role in establishing epithelia-specific junctional structures. J Cell Biol 152: 1183–1196, 2001. Swann AC, Daniel A, Albers RW, and Koval GJ. Interactions of lectins with (Na⫹ ⫹ K⫹)-ATPase of eel electric organ. Biochim Biophys Acta 401: 299 –306, 1975. Sweadner KJ and Donnet C. Structural similarities of Na,KATPase and SERCA, the Ca(2⫹)-ATPase of the sarcoplasmic reticulum. Biochem J 356: 685–704, 2001. Sweadner KJ, Wetzel RK, and Arystarkhova E. Genomic organization of the human FXYD2 gene encoding the gamma subunit of the Na,K-ATPase. Biochem Biophys Res Commun 279: 196 –201, 2000. Takagaki Y and Manley JL. Complex protein interactions within the human polyadenylation machinery identify a novel component. Mol Cell Biol 20: 1515–1525, 2000. Takai Y and Nakanishi H. Nectin and afadin: novel organizers of intercellular junctions. J Cell Sci 116: 17–27, 2003. Takeda H and Tsukita S. Effects of tyrosine phosphorylation on tight junctions in temperature-sensitive v-src-transfected MDCK cells. Cell Struct Funct 20: 387–393, 1995. Takeichi M. Cadherin cell-adhesion receptors as a morphogenetic regulator. Science 251: 1451–1455, 1991. Takeichi M. Morphogenetic roles of classic cadherins. Curr Opin Cell Biol 7: 619 – 627, 1995. Takeyasu K, Lemas V, and Fambrough DM. Stability of Na(⫹)K(⫹)-ATPase alpha-subunit isoforms in evolution. Am J Physiol Cell Physiol 259: C619 –C630, 1990. Takeyasu K, Okamura H, Yasuhara JC, Ogita Y, and Yoshimura SH. P-type ATPase diversity and evolution: the origins of ouabain sensitivity and subunit assembly. Cell Mol Biol 47: 325–333, 2001. Takeyasu K, Renaud KJ, Taormino J, Wolitzkt BA, Barnstein AM, Tamkun MM, and Fambrough DM. Differential subunit and

84 • OCTOBER 2004 •

www.prv.org

ADHESION AND POLARITY IN THE DAWN OF METAZOANS

439.

440. 441.

442.

443. 444.

445. 446.

447.

448.

449.

450.

451. 452.

453.

454. 455.

456.

457.

458. 459.

460.

461.

isoform expression involved in regulation of sodium pump in skeletal muscle. Curr Top Membr Transp 34: 143–165, 1989. Talavera D, Ponce A, Fiorentino R, Gonzalez-Mariscal L, Contreras RG, Sanchez SH, Garcia-Villegas MR, Valdes J, and Cereijido M. Expression of potassium channels in epithelial cells depends on calcium-activated cell-cell contacts. J Membr Biol 143: 219 –226, 1995. Taub M. Tissue Cultured in Epithelial Cells. New York: Plenum, 1985. Taub M and Saier MH Jr. Regulation of 22Na⫹ transport by calcium in an established kidney epithelial cell line. J Biol Chem 254: 11440 –11444, 1979. Taub M, U B, Chuman L, Rindler MJ, Saier MH Jr, and Sato G. Alterations in growth requirements of kidney epithelial cells in defined medium associated with malignant transformation. J Supramol Struct Cell Biochem 15: 63–72, 1981. Tepass U and Hartenstein V. The development of cellular junctions in the Drosophila embryo. Dev Biol 161: 563–596, 1994. Tepass U, Tanentzapf G, Ward R, and Fehon R. Epithelial cell polarity and cell junctions in Drosophila. Annu Rev Genet 35: 747–784, 2001. Therien AG and Blostein R. Mechanisms of sodium pump regulation. Am J Physiol Cell Physiol 279: C541–C566, 2000. Therien AG, Goldshleger R, Karlish SJ, and Blostein R. Tissue-specific distribution and modulatory role of the gamma subunit of the Na,K-ATPase. J Biol Chem 272: 32628 –32634, 1997. Therien AG, Karlish SJ, and Blostein R. Expression and functional role of the gamma subunit of the Na,K-ATPase in mammalian cells. J Biol Chem 274: 12252–12256, 1999. Toshimori K, Iwashita T, and Oura C. Cell junctions in the cyst envelope in the silkworm testis, Bombyx mori Linne. Cell Tissue Res 202: 63–73, 1979. Toyoshima C, Nakasako M, Nomura H, and Ogawa H. Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 A resolution. Nature 405: 647– 655, 2000. Troxell ML, Gopalakrishnan S, McCormack J, Poteat BA, Pennington J, Garringer SM, Schneeberger EE, Nelson WJ, and Marrs JA. Inhibiting cadherin function by dominant mutant E-cadherin expression increases the extent of tight junction assembly. J Cell Sci 113: 985–996, 2000. Tsukita S, Furuse M, and Itoh M. Multifunctional strands in tight junctions. Nat Rev Mol Cell Biol 2: 285–293, 2001. Tsukita S, Itoh M, Nagafuchi A, Yonemura S, and Tsukita S. Submembranous junctional plaque proteins include potential tumor suppressor molecules. J Cell Biol 123: 1049 –1053, 1993. Turin L, Behe P, Plonsky I, and Dunina-Barkovskaya A. Hydrophobic ion transfer between membranes of adjacent hepatocytes: a possible probe of tight junction structure. Proc Natl Acad Sci USA 88: 9365–9369, 1991. Uemura T. The cadherin superfamily at the synapse: more members, more missions. Cell 93: 1095–1098, 1998. Underwood JL, Murphy CG, Chen J, Franse-Carman L, Wood I, Epstein DL, and Alvarado JA. Glucocorticoids regulate transendothelial fluid flow resistance and formation of intercellular junctions. Am J Physiol Cell Physiol 277: C330 –C342, 1999. Ussing HH and Zerahn K. Active transport of sodium as the source of electric current in the short-circuited isolated frog skin. Acta Physiol Scand 23: 110 –127, 1951. Van Itallie C, Rahner C, and Anderson JM. Regulated expression of claudin-4 decreases paracellular conductance through a selective decrease in sodium permeability. J Clin Invest 107: 1319 – 1327, 2001. Van Itallie CM and Anderson JM. Occludin confers adhesiveness when expressed in fibroblasts. J Cell Sci 110: 1113–1121, 1997. Van Itallie CM, Balda MS, and Anderson JM. Epidermal growth factor induces tyrosine phosphorylation and reorganization of the tight junction protein ZO-1 in A431 cells. J Cell Sci 108: 1735–1742, 1995. Van Meer G, Gumbiner B, and Simons K. The tight junction does not allow lipid molecules to diffuse from one epithelial cell to the next. Nature 322: 639 – 641, 1986. Van Meer G and Simons K. The function of tight junctions in maintaining differences in lipid composition between the apical Physiol Rev • VOL

462.

463.

464.

465.

466.

467.

468.

469.

470.

471.

472. 473.

474.

475.

476.

477.

478.

479. 480.

481.

1261

and the basolateral cell surface domains of MDCK cells. EMBO J 5: 1455–1464, 1986. Vasioukhin V, Bauer C, Yin M, and Fuchs E. Directed actin polymerization is the driving force for epithelial cell-cell adhesion. Cell 100: 209 –219, 2000. Velyvis A, Vaynberg J, Yang Y, Vinogradova O, Zhang Y, Wu C, and Qin J. Structural and functional insights into PINCH LIM4 domain-mediated integrin signaling. Nat Struct Biol 10: 558 –564, 2003. Vilsen B, Andersen JP, Petersen J, and Jorgensen PL. Occlusion of 22Na⫹ and 86Rb⫹ in membrane-bound and soluble protomeric alpha beta-units of Na,K-ATPase. J Biol Chem 262: 10511– 10517, 1987. Wang AZ, Wang JC, Ojakian GK, and Nelson WJ. Determinants of apical membrane formation and distribution in multicellular epithelial MDCK cysts. Am J Physiol Cell Physiol 267: C473–C481, 1994. Wang SG, Eakle KA, Levenson R, and Farley RA. Na⫹-K⫹ATPase alpha-subunit containing Q905-V930 of gastric H⫹-K⫹ATPase alpha preferentially assembles with H⫹-K⫹-ATPase beta. Am J Physiol Cell Physiol 272: C923–C930, 1997. Wang SG and Farley RA. Valine 904, tyrosine 898, and cysteine 908 in Na,K-ATPase alpha subunits are important for assembly with beta subunits. J Biol Chem 273: 29400 –29405, 1998. Wang Y and Gilmore TD. Zyxin and paxillin proteins: focal adhesion plaque LIM domain proteins go nuclear. Biochim Biophys Acta 1593: 115–120, 2003. Ward SC, Hamilton BP, and Hamlyn JM. Novel receptors for ouabain: studies in adrenocortical cells and membranes. Hypertension 39: 536 –542, 2002. Watabe-Uchida M, Uchida N, Imamura Y, Nagafuchi A, Fujimoto K, Uemura T, Vermeulen S, Van Roy F, Adamson ED, and Takeichi M. Alpha-catenin-vinculin interaction functions to organize the apical junctional complex in epithelial cells. J Cell Biol 142: 847– 857, 1998. Watts AG, Sanchez-Watts G, Emanuel JR, and Levenson R. Cell-specific expression of mRNAs encoding Na⫹-K⫹-ATPase alpha- and beta-subunit isoforms within the rat central nervous system. Proc Natl Acad Sci USA 88: 7425–7429, 1991. Wedlich-Soldner R and Li R. Spontaneous cell polarization: undermining determinism. Nat Cell Biol 5: 267–270, 2003. Wei Y, Renard CA, Labalette C, Wu Y, Levy L, Neuveut C, Prieur X, Flajolet M, Prigent S, and Buendia MA. Identification of the LIM protein FHL2 as a coactivator of beta-catenin. J Biol Chem 278: 5188 –5194, 2003. Wilcox ER, Burton QL, Naz S, Riazuddin S, Smith TN, Ploplis B, Belyantseva I, Ben Yosef T, Liburd NA, Morell RJ, Kachar B, Wu DK, Griffith AJ, Riazuddin S, and Friedman TB. Mutations in the gene encoding tight junction claudin-14 cause autosomal recessive deafness DFNB29. Cell 104: 165–172, 2001. Wilimer P. Invertebrate Relationships Patterns in Animal Evolution XIII. Cambridge, MA: Cambridge Univ. Press, 1990, p. 1– 4000. Willott E, Balda MS, Heintzelman M, Jameson B, and Anderson JM. Localization and differential expression of two isoforms of the tight junction protein ZO-1. Am J Physiol Cell Physiol 262: C1119 –C1124, 1992. Wittchen ES, Haskins J, and Stevenson BR. Protein interactions at the tight junction. Actin has multiple binding partners, and ZO-1 forms independent complexes with ZO-2 and ZO-3. J Biol Chem 274: 35179 –35185, 1999. Wittchen ES, Haskins J, and Stevenson BR. Nzo-3 expression causes global changes to actin cytoskeleton in Madin-Darby canine kidney cells: linking a tight junction protein to Rho GTPases. Mol Biol Cell 14: 1757–1768, 2003. Wodarz A. Establishing cell polarity in development. Nat Cell Biol 4: E39 –E44, 2002. Wong V and Gumbiner BM. A synthetic peptide corresponding to the extracellular domain of occludin perturbs the tight junction permeability barrier. J Cell Biol 136: 399 – 409, 1997. Woo AL, James PF, and Lingrel JB. Characterization of the fourth alpha isoform of the Na,K-ATPase. J Membr Biol 169: 39 – 44, 1999.

84 • OCTOBER 2004 •

www.prv.org

1262

CEREIJIDO, CONTRERAS, AND SHOSHANI

482. Wood RL. Intercellular attachment in the epithelium of Hydra as revealed by electron microscopy. J Biophys Biochem Cytol 6: 343–352, 1959. 483. Woods DF and Bryant PJ. The discs-large tumor suppressor gene of Drosophila encodes a guanylate kinase homolog localized at septate junctions. Cell 66: 451– 464, 1991. 484. Wright EM. Mechanisms of ion transport across the choroid plexus. J Physiol 226: 545–571, 1972. 485. Wu Q and Maniatis T. Large exons encoding multiple ectodomains are a characteristic feature of protocadherin genes. Proc Natl Acad Sci USA 97: 3124 –3129, 2000. 486. Wu VM, Paul S, Schutle J, Tepass U, and Beitel GL. A claudin and specific isoforms of Na,K-ATPase are required for Drosophila epithelial tube-size control and septate junction organization. 43rd Annu Meet Am Soc Cell Biol San Francisco CA 2003, p. L308. 487. Wu VM, Schulte J, Hirschi A, Tepass U, and Beitel GJ. Sinuous is a Drosophila claudin required for septate junction organization and epithelial tube size control. J Cell Biol 164: 313–323, 2004. 488. Wu X, Hepner K, Castelino-Prabhu S, Do D, Kaye MB, Yuan XJ, Wood J, Ross C, Sawyers CL, and Whang YE. Evidence for regulation of the PTEN tumor suppressor by a membrane-localized multi-PDZ domain containing scaffold protein MAGI-2. Proc Natl Acad Sci USA 97: 4233– 4238, 2000. 489. Wu Y, Dowbenko D, Spencer S, Laura R, Lee J, Gu Q, and Lasky LA. Interaction of the tumor suppressor PTEN/MMAC with a PDZ domain of MAGI3, a novel membrane-associated guanylate kinase. J Biol Chem 275: 21477–21485, 2000. 490. Xu P, Sun B, and Salvaterra PM. Organization and transcriptional regulation of Drosophila Na(⫹), K(⫹)-ATPase beta subunit genes: Nrv1 and Nrv2. Gene 236: 303–313, 1999. 491. Yamamoto T, Harada N, Kano K, Taya S, Canaani E, Matsuura Y, Mizoguchi A, Ide C, and Kaibuchi K. The Ras target AF-6 interacts with ZO-1 and serves as a peripheral component of tight junctions in epithelial cells. J Cell Biol 139: 785–795, 1997.

Physiol Rev • VOL

492. Yamashita YM, Jones DL, and Fuller MT. Orientation of asymmetric stem cell division by the APC tumor suppressor and centrosome. Science 301: 1547–1550, 2003. 493. Yamazaki M, Furuike S, and Ito T. Mechanical response of single filamin A (ABP-280) molecules and its role in the actin cytoskeleton. J Muscle Res Cell Motil 23: 525–534, 2002. 494. Yang L, Guerrero J, Hong H, Defranco DB, and Stallcup MR. Interaction of the tau2 transcriptional activation domain of glucocorticoid receptor with a novel steroid receptor coactivator, Hic-5, which localizes to both focal adhesions and the nuclear matrix. Mol Biol Cell 11: 2007–2018, 2000. 495. Yap AS, Brieher WM, and Gumbiner BM. Molecular and functional analysis of cadherin-based adherens junctions. Annu Rev Cell Dev Biol 13: 119 –146, 1997. 496. Yeaman C, Grindstaff KK, and Nelson WJ. New perspectives on mechanisms involved in generating epithelial cell polarity. Physiol Rev 79: 73–98, 1999. 497. Zahraoui A, Joberty G, Arpin M, Fontaine JJ, Hellio R, Tavitian A, and Louvard D. A small rab GTPase is distributed in cytoplasmic vesicles in non polarized cells but colocalizes with the tight junction marker ZO-1 in polarized epithelial cells. J Cell Biol 124: 101–115, 1994. 498. Zhang Z, Devarajan P, Dorfman AL, and Morrow JS. Structure of the ankyrin-binding domain of alpha-Na,K-ATPase. J Biol Chem 273: 18681–18684, 1998. 499. Zurzolo C and Rodriguez-Boulan E. Delivery of Na⫹-K⫹-ATPase in polarized epithelial cells. Science 260: 550 –552, 1993. 500. Zylber EA, Rotunno CA, and Cereijido M. Ion and water balance in isolated epithelial cells of the abdominal skin of the frog Leptodactylus ocellatus. J Membr Biol 13: 199 –216, 1973. 501. Zylber EA, Rotunno CA, and Cereijido M. Ionic fluxes in isolated epithelial cells of the abdominal skin of the frog Leptodactylus ocellatus. J Membr Biol 22: 265–284, 1975.

84 • OCTOBER 2004 •

www.prv.org