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Liu L, Ivanov AV, Gable ME, Jolivel F, Morrill GA, Askari A. Comparative properties of caveolar and noncaveolar preparations of kidney Na+/K+-ATPase. Biochemistry 2011; 50:8664-73. [PMID: 21905705 PMCID: PMC3186040 DOI: 10.1021/bi2009008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
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To evaluate previously proposed functions of renal caveolar
Na+/K+-ATPase, we modified the standard procedures
for the preparation of the purified membrane-bound kidney enzyme,
separated the caveolar and noncaveolar pools, and compared their properties.
While the subunits of Na+/K+-ATPase (α,β,γ)
constituted most of the protein content of the noncaveolar pool, the
caveolar pool also contained caveolins and major caveolar proteins
annexin-2 tetramer and E-cadherin. Ouabain-sensitive Na+/K+-ATPase activities of the two pools had similar properties
and equal molar activities, indicating that the caveolar enzyme retains
its ion transport function and does not contain nonpumping enzyme.
As minor constituents, both caveolar and noncaveolar pools also contained
Src, EGFR, PI3K, and several other proteins known to be involved in
stimulous-induced signaling by Na+/K+-ATPase,
indicating that signaling function is not limited to the caveolar
pool. Endogenous Src was active in both pools but was not further
activated by ouabain, calling into question direct interaction of
Src with native Na+/K+-ATPase. Chemical cross-linking,
co-immunoprecipitation, and immunodetection studies showed that in
the caveolar pool, caveolin-1 oligomers, annexin-2 tetramers, and
oligomers of the α,β,γ-protomers of Na+/K+-ATPase form a large multiprotein complex. In conjunction
with known roles of E-cadherin and the β-subunit of Na+/K+-ATPase in cell adhesion and noted intercellular β,β-contacts
within the structure of Na+/K+-ATPase, our findings
suggest that interacting caveolar Na+/K+-ATPases
located at renal adherens junctions maintain contact of two adjacent
cells, conduct essential ion pumping, and are capable of locus-specific
signaling in junctional cells.
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Affiliation(s)
- Lijun Liu
- Department of Biochemistry and Cancer Biology, University of Toledo Health Science Campus, Toledo, Ohio 43614, United States
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52
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Chambers KF, Pearson JF, Pellacani D, Aziz N, Gužvić M, Klein CA, Lang SH. Stromal upregulation of lateral epithelial adhesions: gene expression analysis of signalling pathways in prostate epithelium. J Biomed Sci 2011; 18:45. [PMID: 21696611 PMCID: PMC3141633 DOI: 10.1186/1423-0127-18-45] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 06/22/2011] [Indexed: 01/05/2023] Open
Abstract
Background Stromal signalling increases the lateral cell adhesions of prostate epithelial cells grown in 3D culture. The aim of this study was to use microarray analysis to identify significant epithelial signalling pathways and genes in this process. Methods Microarray analysis was used to identify genes that were differentially expressed when epithelial cells were grown in 3D Matrigel culture with stromal co-culture compared to without stroma. Two culture models were employed: primary epithelial cells (ten samples) and an epithelial cell line (three experiments). A separate microarray analysis was performed on each model system and then compared to identify tissue-relevant genes in a cell line model. Results TGF beta signalling was significantly ranked for both model systems and in both models the TGF beta signalling gene SOX4 was significantly down regulated. Analysis of all differentially expressed genes to identify genes that were common to both models found several morphology related gene clusters; actin binding (DIAPH2, FHOD3, ABLIM1, TMOD4, MYH10), GTPase activator activity (BCR, MYH10), cytoskeleton (MAP2, MYH10, TMOD4, FHOD3), protein binding (ITGA6, CD44), proteinaceous extracellular matrix (NID2, CILP2), ion channel/ ion transporter activity (CACNA1C, CACNB2, KCNH2, SLC8A1, SLC39A9) and genes associated with developmental pathways (POFUT1, FZD2, HOXA5, IRX2, FGF11, SOX4, SMARCC1). Conclusions In 3D prostate cultures, stromal cells increase lateral epithelial cell adhesions. We show that this morphological effect is associated with gene expression changes to TGF beta signalling, cytoskeleton and anion activity.
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Affiliation(s)
- Karen F Chambers
- Yorkshire Cancer Research Unit, Dept, Biology, University of York, Heslington, York YO10 5YW, UK
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53
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Studer RA, Person E, Robinson-Rechavi M, Rossier BC. Evolution of the epithelial sodium channel and the sodium pump as limiting factors of aldosterone action on sodium transport. Physiol Genomics 2011; 43:844-54. [PMID: 21558422 DOI: 10.1152/physiolgenomics.00002.2011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Despite large changes in salt intake, the mammalian kidney is able to maintain the extracellular sodium concentration and osmolarity within very narrow margins, thereby controlling blood volume and blood pressure. In the aldosterone-sensitive distal nephron (ASDN), aldosterone tightly controls the activities of epithelial sodium channel (ENaC) and Na,K-ATPase, the two limiting factors in establishing transepithelial sodium transport. It has been proposed that the ENaC/degenerin gene family is restricted to Metazoans, whereas the α- and β-subunits of Na,K-ATPase have homologous genes in prokaryotes. This raises the question of the emergence of osmolarity control. By exploring recent genomic data of diverse organisms, we found that: 1) ENaC/degenerin exists in all of the Metazoans screened, including nonbilaterians and, by extension, was already present in ancestors of Metazoa; 2) ENaC/degenerin is also present in Naegleria gruberi, an eukaryotic microbe, consistent with either a vertical inheritance from the last common ancestor of Eukaryotes or a lateral transfer between Naegleria and Metazoan ancestors; and 3) The Na,K-ATPase β-subunit is restricted to Holozoa, the taxon that includes animals and their closest single-cell relatives. Since the β-subunit of Na,K-ATPase plays a key role in targeting the α-subunit to the plasma membrane and has an additional function in the formation of cell junctions, we propose that the emergence of Na,K-ATPase, together with ENaC/degenerin, is linked to the development of multicellularity in the Metazoan kingdom. The establishment of multicellularity and the associated extracellular compartment ("internal milieu") precedes the emergence of other key elements of the aldosterone signaling pathway.
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Affiliation(s)
- Romain A Studer
- Department of Ecology and Evolution, Biophore, Lausanne, Switzerland.
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Claudin-2 expression increases tumorigenicity of colon cancer cells: role of epidermal growth factor receptor activation. Oncogene 2011; 30:3234-47. [PMID: 21383692 PMCID: PMC3591522 DOI: 10.1038/onc.2011.43] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Claudin-2 is a unique member of the claudin family of transmembrane proteins as its expression is restricted to the leaky epithelium in vivo and correlates with epithelial leakiness in vitro. However, recent evidence suggests potential functions of claudin-2 that are relevant to neoplastic transformation and growth. In accordance here we report, based upon analysis of mRNA and protein expression using a total of 309 patient samples, that claudin-2 expression is significantly increased in colorectal cancer and correlates with cancer progression. We also report similar increases in claudin-2 expression in inflammatory bowel disease (IBD)-associated colorectal cancer. Most importantly, we demonstrate that the increased claudin-2 expression in colorectal cancer is causally associated with tumor growth as forced claudin-2 expression in colon cancer cells that do not express claudin-2 resulted in significant increases in cell proliferation, anchorage-independent growth, and tumor growth in vivo. We further show that the colonic microenvironment regulates claudin-2 expression in a manner dependent on signaling through the EGF receptor (EGFR), a key regulator of colon tumorigenesis. In addition, claudin-2 expression is specifically decreased in the colon of waved-2 mice, naturally deficient in EGFR activation. Furthermore, genetic silencing of claudin-2 expression in Caco-2 , a colon cancer cell line, prevents the EGF-induced increase in cell proliferation. Taken together, these results uncover a novel role for claudin-2 in promoting colon cancer, potentially via EGFR transactivation.
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55
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Adams EDM, Goss GG, Leys SP. Freshwater sponges have functional, sealing epithelia with high transepithelial resistance and negative transepithelial potential. PLoS One 2010; 5:e15040. [PMID: 21124779 PMCID: PMC2993944 DOI: 10.1371/journal.pone.0015040] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 10/13/2010] [Indexed: 11/18/2022] Open
Abstract
Epithelial tissue - the sealed and polarized layer of cells that regulates transport of ions and solutes between the environment and the internal milieu - is a defining characteristic of the Eumetazoa. Sponges, the most ancient metazoan phylum, are generally believed to lack true epithelia, but their ability to occlude passage of ions has never been tested. Here we show that freshwater sponges (Demospongiae, Haplosclerida) have functional epithelia with high transepithelial electrical resistance (TER), a transepithelial potential (TEP), and low permeability to small-molecule diffusion. Curiously, the Amphimedon queenslandica sponge genome lacks the classical occluding genes [5] considered necessary to regulate sealing and control of ion transport. The fact that freshwater sponge epithelia can seal suggests that either occluding molecules have been lost in some sponge lineages, or demosponges use novel molecular complexes for epithelial occlusion; if the latter, it raises the possibility that mechanisms for occlusion used by sponges may exist in other metazoa. Importantly, our results imply that functional epithelia evolved either several times, or once, in the ancestor of the Metazoa.
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Affiliation(s)
- Emily D. M. Adams
- Physiology, Cell and Developmental Biology Group, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Greg G. Goss
- Physiology, Cell and Developmental Biology Group, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Sally P. Leys
- Physiology, Cell and Developmental Biology Group, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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56
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Nelson WJ. Remodeling epithelial cell organization: transitions between front-rear and apical-basal polarity. Cold Spring Harb Perspect Biol 2010; 1:a000513. [PMID: 20066074 DOI: 10.1101/cshperspect.a000513] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Polarized epithelial cells have a distinctive apical-basal axis of polarity for vectorial transport of ions and solutes across the epithelium. In contrast, migratory mesenchymal cells have a front-rear axis of polarity. During development, mesenchymal cells convert to epithelia by coalescing into aggregates that undergo epithelial differentiation. Signaling networks and protein complexes comprising Rho family GTPases, polarity complexes (Crumbs, PAR, and Scribble), and their downstream effectors, including the cytoskeleton and the endocytic and exocytic vesicle trafficking pathways, together regulate the distributions of plasma membrane and cytoskeletal proteins between front-rear and apical-basal polarity. The challenge is to understand how these regulators and effectors are adapted to regulate symmetry breaking processes that generate cell polarities that are specialized for different cellular activities and functions.
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Affiliation(s)
- W James Nelson
- Department of Biology, Stanford University, Stanford, California 94305, USA.
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57
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A developmental framework for endodermal differentiation and polarity. Proc Natl Acad Sci U S A 2010; 107:5214-9. [PMID: 20142472 DOI: 10.1073/pnas.0910772107] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The endodermis is a root cell layer common to higher plants and of fundamental importance for root function and nutrient uptake. The endodermis separates outer (peripheral) from inner (central) cell layers by virtue of its Casparian strips, precisely aligned bands of specialized wall material. Here we reveal that the membrane at the Casparian strip is a diffusional barrier between the central and peripheral regions of the plasma membrane and that it mediates attachment to the extracellular matrix. This membrane region thus functions like a tight junction in animal epithelia, although plants lack the molecular modules that establish tight junction in animals. We have also identified a pair of influx and efflux transporters that mark both central and peripheral domains of the plasma membrane. These transporters show opposite polar distributions already in meristems, but their localization becomes refined and restricted upon differentiation. This "central-peripheral" polarity coexists with the apical-basal polarity defined by PIN proteins within the same cells, but utilizes different polarity determinants. Central-peripheral polarity can be already observed in early embryogenesis, where it reveals a cellular polarity within the quiescent center precursor cell. A strict diffusion block between polar domains is common in animals, but had never been described in plants. Yet, its relevance to endodermal function is evident, as central and peripheral membranes of the endodermis face fundamentally different root compartments. Further analysis of endodermal transporter polarity and manipulation of its barrier function will greatly promote our understanding of plant nutrition and stress tolerance in roots.
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58
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Rotaviruses require basolateral molecules for efficient infection of polarized MDCKII cells. Virus Res 2010; 147:231-41. [DOI: 10.1016/j.virusres.2009.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2009] [Revised: 11/09/2009] [Accepted: 11/13/2009] [Indexed: 11/21/2022]
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Wong EWP, Cheng CY. Polarity proteins and cell-cell interactions in the testis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 278:309-53. [PMID: 19815182 DOI: 10.1016/s1937-6448(09)78007-4] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In mammalian testes, extensive junction restructuring takes place in the seminiferous epithelium at the Sertoli-Sertoli and Sertoli-germ cell interface to facilitate the different cellular events of spermatogenesis, such as mitosis, meiosis, spermiogenesis, and spermiation. Recent studies in the field have shown that Rho GTPases and polarity proteins play significant roles in the events of cell-cell interactions. Furthermore, Rho GTPases, such as Cdc42, are working in concert with polarity proteins in regulating cell polarization and cell adhesion at both the blood-testis barrier (BTB) and apical ectoplasmic specialization (apical ES) in the testis of adult rats. In this chapter, we briefly summarize recent findings on the latest status of research and development regarding Cdc42 and polarity proteins and how they affect cell-cell interactions in the testis and other epithelia. More importantly, we provide a new model in which how Cdc42 and components of the polarity protein complexes work in concert with laminin fragments, cytokines, and testosterone to regulate the events of cell-cell interactions in the seminiferous epithelium via a local autocrine-based regulatory loop known as the apical ES-BTB-basement membrane axis. This new functional axis coordinates various cellular events during different stages of the seminiferous epithelium cycle of spermatogenesis.
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Affiliation(s)
- Elissa W P Wong
- Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065, USA
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60
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Steed E, Rodrigues NTL, Balda MS, Matter K. Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family. BMC Cell Biol 2009; 10:95. [PMID: 20028514 PMCID: PMC2805614 DOI: 10.1186/1471-2121-10-95] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 12/22/2009] [Indexed: 02/06/2023] Open
Abstract
Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link) domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.
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Affiliation(s)
- Emily Steed
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK.
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Groschwitz KR, Hogan SP. Intestinal barrier function: molecular regulation and disease pathogenesis. J Allergy Clin Immunol 2009; 124:3-20; quiz 21-2. [PMID: 19560575 PMCID: PMC4266989 DOI: 10.1016/j.jaci.2009.05.038] [Citation(s) in RCA: 1109] [Impact Index Per Article: 73.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 05/22/2009] [Accepted: 05/27/2009] [Indexed: 02/08/2023]
Abstract
The intestinal epithelium is a single-cell layer that constitutes the largest and most important barrier against the external environment. It acts as a selectively permeable barrier, permitting the absorption of nutrients, electrolytes, and water while maintaining an effective defense against intraluminal toxins, antigens, and enteric flora. The epithelium maintains its selective barrier function through the formation of complex protein-protein networks that mechanically link adjacent cells and seal the intercellular space. The protein networks connecting epithelial cells form 3 adhesive complexes: desmosomes, adherens junctions, and tight junctions. These complexes consist of transmembrane proteins that interact extracellularly with adjacent cells and intracellularly with adaptor proteins that link to the cytoskeleton. Over the past decade, there has been increasing recognition of an association between disrupted intestinal barrier function and the development of autoimmune and inflammatory diseases. In this review we summarize the evolving understanding of the molecular composition and regulation of intestinal barrier function. We discuss the interactions between innate and adaptive immunity and intestinal epithelial barrier function, as well as the effect of exogenous factors on intestinal barrier function. Finally, we summarize clinical and experimental evidence demonstrating intestinal epithelial barrier dysfunction as a major factor contributing to the predisposition to inflammatory diseases, including food allergy, inflammatory bowel diseases, and celiac disease.
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Affiliation(s)
- Katherine R. Groschwitz
- Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH
- Division of Immunobiology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH
| | - Simon P. Hogan
- Division of Allergy and Immunology, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH
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Novel mutations affecting the Na, K ATPase alpha model complex neurological diseases and implicate the sodium pump in increased longevity. Hum Genet 2009; 126:431-47. [PMID: 19455355 PMCID: PMC2791699 DOI: 10.1007/s00439-009-0673-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 04/14/2009] [Indexed: 01/29/2023]
Abstract
Mutations affecting the Na+, K+ ATPase alpha subunit have been implicated in at least two distinct human diseases, rapid-onset dystonia Parkinsonism (RDP), and familial hemiplegic migraine (FHM). Over 40 mutations have been mapped to the human ATP1A2 and ATP1A3 genes and are known to result in RDP, FHM or a variant of FHM with neurological complications. To develop a genetically tractable model system for investigating the role of the Na+, K+ ATPase in neural pathologies we performed genetic screens in Drosophila melanogaster to isolate loss-of-function alleles affecting the Na+, K+ ATPase alpha subunit. Flies heterozygous for these mutations all exhibit reduced respiration, consistent with a loss-of-function in the major ATPase. However, these mutations do not affect all functions of the Na+, K+ ATPase alpha protein since embryos homozygous for these mutations have normal septate junction paracellular barrier function and tracheal morphology. Importantly, all of these mutations cause neurological phenotypes and, akin to the mutations that cause RDP and FHM, these new alleles are missense mutations. All of these alleles exhibit progressive stress-induced locomotor impairment suggesting neuromuscular dysfunction, yet neurodegeneration is observed in an allele-specific manner. Surprisingly, studies of longevity demonstrate that mild hypomorphic mutations in the sodium pump significantly improve longevity, which was verified using the Na+, K+ ATPase antagonist ouabain. The isolation and characterization of a series of new missense alleles of ATPalpha in Drosophila provides the foundation for further studies of these neurological diseases and the role of sodium pump impairment in animal longevity.
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63
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Sáez AG, Lozano E, Zaldívar-Riverón A. Evolutionary history of Na,K-ATPases and their osmoregulatory role. Genetica 2009; 136:479-90. [PMID: 19214758 DOI: 10.1007/s10709-009-9356-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Accepted: 01/26/2009] [Indexed: 01/07/2023]
Abstract
The Na/K pump, or Na,K-ATPase, is a key enzyme to the homeostasis of osmotic pressure, cell volume, and the maintenance of electrochemical gradients. Its alpha subunit, which holds most of its functions, belongs to a large family of ATPases known as P-type, and to the subfamily IIC, which also includes H,K-ATPases. In this study, we attempt to describe the evolutionary history of IIC ATPases by doing phylogenetic analysis with most of the currently available protein sequences (over 200), and pay special attention to the relationship between their diversity and their osmoregulatory role. We include proteins derived from many completed or ongoing genome projects, many of whose IIC ATPases have not been phylogenetically analyzed previously. We show that the most likely origin of IIC proteins is prokaryotic, and that many of them are present in non-metazoans, such as algae, protozoans or fungi. We also suggest that the pre-metazoan ancestor, represented by the choanoflagellate Monosiga brevicollis, whose genome has been sequenced, presented at least two IIC-type proteins. One of these proteins would have given rise to most current animal IIC ATPases, whereas the other apparently evolved into a lineage that, so far, has only been found in nematodes. We also propose that early deuterostomes presented a single IIC gene, from which all the extant diversity of vertebrate IIC proteins originated by gene and genome duplications.
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Affiliation(s)
- Alberto G Sáez
- Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain.
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64
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65
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The epithelial polarity program: machineries involved and their hijacking by cancer. Oncogene 2008; 27:6939-57. [DOI: 10.1038/onc.2008.345] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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66
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Magie CR, Martindale MQ. Cell-cell adhesion in the cnidaria: insights into the evolution of tissue morphogenesis. THE BIOLOGICAL BULLETIN 2008; 214:218-232. [PMID: 18574100 DOI: 10.2307/25470665] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cell adhesion is a major aspect of cell biology and one of the fundamental processes involved in the development of a multicellular animal. Adhesive mechanisms, both cell-cell and between cell and extracellular matrix, are intimately involved in assembling cells into the three-dimensional structures of tissues and organs. The modulation of adhesive complexes could therefore be seen as a central component in the molecular control of morphogenesis, translating information encoded within the genome into organismal form. The availability of whole genomes from early-branching metazoa such as cnidarians is providing important insights into the evolution of adhesive processes by allowing for the easy identification of the genes involved in adhesion in these organisms. Discovery of the molecular nature of cell adhesion in the early-branching groups, coupled with comparisons across the metazoa, is revealing the ways evolution has tinkered with this vital cellular process in the generation of the myriad forms seen across the animal kingdom.
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Affiliation(s)
- Craig R Magie
- Kewalo Marine Laboratory, Pacific Biomedical Research Center, University of Hawai'i Honolulu, Hawaii 96813, USA
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67
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García-Villegas R, Escamilla J, Fiorentino R, Cereijido M. Potassium Channels Lost During Harvesting of Epithelial Cells are Restored with a Kinetics that Depends on Channel Species. Cell Physiol Biochem 2008; 20:405-16. [PMID: 17762168 DOI: 10.1159/000107525] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/28/2007] [Indexed: 01/01/2023] Open
Abstract
The polarized distribution of K(+) channels in MDCK cells is lost upon harvesting and restored upon re-seeding. Using semi-quantitative PCR, in the present work we find that (i) Cells do not "wait" for the normal recycling of membrane proteins to restore their lost channels, but trigger their replacement, suggesting that the membrane has a way of engaging the nucleus. (ii) Replacement channels do not come from an internal reservoir, as it is the case with Na(+), K(+)-ATPase, but requires a de novo synthesis. (iii) Replacement is not an all-or-none response, since mRNA for MaxiK channels increases by 8-fold after re-seeding, but those for Kv1.6 and Kv1.7 are not affected by harvesting/re-seeding. (iv) TEA, charybdotoxin and iberiotoxin fail to trigger the replacement response in mature monolayers, suggesting that replacement is not due to suppression of channel function. (v) MDCK cells have a typical transporting epithelial phenotype (TEP) consisting of tight junctions (TJs) plus polarity. Although the polarized distribution of K-channels is a prominent attribute of TEP, blocking their function does not perturb the development of TEP, as gauged through the development of TJs, nor level of expression (Western blot) and distribution (confocal microscopy) of occludin, and claudins 1, 3 and 7.
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Konecny GE, Agarwal R, Keeney GA, Winterhoff B, Jones MB, Mariani A, Riehle D, Neuper C, Dowdy SC, Wang HJ, Morin PJ, Podratz KC. Claudin-3 and claudin-4 expression in serous papillary, clear-cell, and endometrioid endometrial cancer. Gynecol Oncol 2008; 109:263-9. [PMID: 18313739 DOI: 10.1016/j.ygyno.2008.01.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2007] [Revised: 01/03/2008] [Accepted: 01/07/2008] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Tight junction (TJ) proteins claudin-3 and claudin-4 may be differentially expressed in uterine serous papillary carcinoma (USPC), a rare form of endometrial cancer characterized by a particularly poor prognosis. Our aim was to determine the expression pattern and prognostic relevance of claudin-3 and claudin-4 in a large cohort of endometrial cancer patients of diverse histological type and stage. METHODS Claudin-3 and claudin-4 expression was studied in a cohort of 287 patients with endometrial cancer including 137 cases of USPC or clear-cell histology using immunohistochemistry. Patients were completely surgically staged. Outcome data is available on all 287 patients. RESULTS The rate of claudin-3 and claudin-4 expression was significantly higher in USPC and clear-cell endometrial cancer compared to endometrioid endometrial cancer (claudin-3: 78% and 61% versus 38%, p<.0001; claudin-4: 56% and 44% versus 9%, p<.0001). Furthermore, expression of both TJ proteins was significantly associated with poor clinical outcome (claudin-3, DFS RR 1.70, p=.0087, OS RR 1.62, p=.0247; claudin-4, DFS RR 2.66, p<0.0001, and OS RR 2.50, p<0.0001). However, both markers did not maintain prognostic independence in multivariate analyses, as their expression was tightly associated with more advanced disease stages (p<.0001 for both), and higher nuclear grade (p<.0001 for both). CONCLUSION These clinical observations confirm the hypothesis based on preclinical evidence that increased expression of claudin-3 and claudin-4 may contribute to the aggressive phenotype of endometrial cancer of serous papillary or clear-cell histology and suggest their potential utility as diagnostic biomarkers and possible targets for therapeutic intervention.
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Affiliation(s)
- Gottfried E Konecny
- Department of Obstetrics and Gynecology, Mayo Clinic, Rochester, Minnesota 55905, USA
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69
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Paris L, Tonutti L, Vannini C, Bazzoni G. Structural organization of the tight junctions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:646-59. [DOI: 10.1016/j.bbamem.2007.08.004] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 08/01/2007] [Accepted: 08/02/2007] [Indexed: 02/01/2023]
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70
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The Na+/I symporter (NIS) mediates electroneutral active transport of the environmental pollutant perchlorate. Proc Natl Acad Sci U S A 2007; 104:20250-5. [PMID: 18077370 DOI: 10.1073/pnas.0707207104] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Na(+)/I(-) symporter (NIS) is a key plasma membrane protein that mediates active I(-) uptake in the thyroid, lactating breast, and other tissues with an electrogenic stoichiometry of 2 Na(+) per I(-). In the thyroid, NIS-mediated I(-) uptake is the first step in the biosynthesis of the iodine-containing thyroid hormones, which are essential early in life for proper CNS development. In the lactating breast, NIS mediates the translocation of I(-) to the milk, thus supplying this essential anion to the nursing newborn. Perchlorate (ClO(4)(-)) is a well known competitive inhibitor of NIS. Exposure to food and water contaminated with ClO(4)(-) is common in the U.S. population, and the public health impact of such exposure is currently being debated. To date, it is still uncertain whether ClO(4)(-) is a NIS blocker or a transported substrate of NIS. Here we show in vitro and in vivo that NIS actively transports ClO(4)(-), including ClO(4)(-) translocation to the milk. A simple mathematical fluxes model accurately predicts the effect of ClO(4)(-) transport on the rate and extent of I(-) accumulation. Strikingly, the Na(+)/ ClO(4)(-) transport stoichiometry is electroneutral, uncovering that NIS translocates different substrates with different stoichiometries. That NIS actively concentrates ClO(4)(-) in maternal milk suggests that exposure of newborns to high levels of ClO(4)(-) may pose a greater health risk than previously acknowledged because ClO(4)(-) would thus directly inhibit the newborns' thyroidal I(-) uptake.
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71
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Aijaz S, Sanchez-Heras E, Balda MS, Matter K. Regulation of tight junction assembly and epithelial morphogenesis by the heat shock protein Apg-2. BMC Cell Biol 2007; 8:49. [PMID: 18028534 PMCID: PMC2211299 DOI: 10.1186/1471-2121-8-49] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 11/20/2007] [Indexed: 01/08/2023] Open
Abstract
Background Tight junctions are required for epithelial barrier formation and participate in the regulation of signalling mechanisms that control proliferation and differentiation. ZO-1 is a tight junction-associated adaptor protein that regulates gene expression, junction assembly and epithelial morphogenesis. We have previously demonstrated that the heat shock protein Apg-2 binds ZO-1 and thereby regulates its role in cell proliferation. Here, we addressed the question whether Apg-2 is also important for junction formation and epithelial morphogenesis. Results We demonstrate that depletion of Apg-2 by RNAi in MDCK cells did not prevent formation of functional tight junctions. Similar to ZO-1, however, reduced expression of Apg-2 retarded de novo junction assembly if analysed in a Ca-switch model. Formation of functional junctions, as monitored by measuring transepithelial electrical resistance, and recruitment of tight and adherens junction markers were retarded. If cultured in three dimensional extracellular matrix gels, Apg-2 depleted cells, as previously shown for ZO-1 depleted cells, did not form hollow polarised cysts but poorly organised, irregular structures. Conclusion Our data indicate that Apg-2 regulates junction assembly and is required for normal epithelial morphogenesis in a three-dimensional culture system, suggesting that Apg-2 is an important regulator of epithelial differentiation. As the observed phenotypes are similar to those previously described for ZO-1 depleted cells and depletion of Apg-2 retards junctional recruitment of ZO-1, regulation of ZO-1 is likely to be an important functional role for Apg-2 during epithelial differentiation.
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Affiliation(s)
- Saima Aijaz
- Division of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, UK.
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72
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Cereijido M, Contreras RG, Flores-Benítez D, Flores-Maldonado C, Larre I, Ruiz A, Shoshani L. New diseases derived or associated with the tight junction. Arch Med Res 2007; 38:465-78. [PMID: 17560451 DOI: 10.1016/j.arcmed.2007.02.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Accepted: 02/20/2007] [Indexed: 01/28/2023]
Abstract
The space between neighboring epithelial cells is sealed by the tight junction (TJ). When this seal is leaky, such as in the proximal tubule of the kidney or the gallbladder, substances may cross the epithelium between the cells (paracellular pathway). Yet, when TJs are really hermetic, as is the case in the epithelium of the urinary bladder or the colon, substances can mainly cross the epithelium through the transcellular pathway. The structure of the TJ involves (so far) some 50-odd protein species. Failure of any of these components causes a variety of diseases, some of them so serious that fetuses are not viable. A fast-growing number of diseases are recognized to depend or involve alterations in the TJ. These include autoimmune diseases, in which intestinal TJs allow the passage of antigens from the intestinal flora, challenging the immune system to produce antibodies that may cross react with proteins in the brain, thyroid gland or pancreas. TJs are also involved in cancer development, infections, allergies, etc. The present article does not catalogue all TJ diseases known so far, but describes one of each type as illustration. It also depicts the efforts being made to find pharmaceutical agents that would seal faulty TJs or release their grip to allow for the passage of large molecules through the upper respiratory and digestive tracts, such as insulin, thyroid, appetite-regulatory peptide, etc.
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73
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Cereijido M, Contreras RG, Shoshani L, Flores-Benitez D, Larre I. Tight junction and polarity interaction in the transporting epithelial phenotype. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:770-93. [PMID: 18028872 DOI: 10.1016/j.bbamem.2007.09.001] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2007] [Revised: 08/28/2007] [Accepted: 09/03/2007] [Indexed: 12/21/2022]
Abstract
Development of tight junctions and cell polarity in epithelial cells requires a complex cellular machinery to execute an internal program in response to ambient cues. Tight junctions, a product of this machinery, can act as gates of the paracellular pathway, fences that keep the identity of plasma membrane domains, bridges that communicate neighboring cells. The polarization internal program and machinery are conserved in yeast, worms, flies and mammals, and in cell types as different as epithelia, neurons and lymphocytes. Polarization and tight junctions are dynamic features that change during development, in response to physiological and pharmacological challenges and in pathological situations like infection.
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Affiliation(s)
- Marcelino Cereijido
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV, AP 14-740, México D.F. 07000, México.
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74
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Matter K, Balda MS. Epithelial tight junctions, gene expression and nucleo-junctional interplay. J Cell Sci 2007; 120:1505-11. [PMID: 17452622 DOI: 10.1242/jcs.005975] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Tight junctions are components of the junctional complex linking neighbouring epithelial cells and are important for barrier formation. Recent evidence suggests that tight junctions also participate in signal transduction mechanisms that regulate epithelial cell proliferation, gene expression, differentiation and morphogenesis. One important class of tight-junction-associated signal transduction mechanism is based on dual localisation of certain proteins both at junctions and in the nucleus. These proteins and their partners participate in various steps of gene expression, ranging from regulation of transcription and chromatin structure to mRNA processing and translation. In cancer tissues, their expression is often deregulated in a manner that suggests that tight junctions function as suppressors of proliferation and transformation.
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Affiliation(s)
- Karl Matter
- Division of Cell Biology, Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, UK.
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75
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Kavanagh E, Buchert M, Tsapara A, Choquet A, Balda MS, Hollande F, Matter K. Functional interaction between the ZO-1-interacting transcription factor ZONAB/DbpA and the RNA processing factor symplekin. J Cell Sci 2007; 119:5098-105. [PMID: 17158914 DOI: 10.1242/jcs.03297] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Epithelial tight junctions participate in the regulation of gene expression by controlling the activity of transcription factors that can interact with junctional components. One such protein is the Y-box transcription factor ZONAB/DbpA that binds to ZO-1, a component of the junctional plaque. Symplekin, another nuclear protein that can associate with tight junctions, functions in the regulation of polyadenylation and thereby promotes gene expression. Here, we addressed the question of whether these two proteins interact and whether this is of functional relevance. We demonstrate that ZONAB/DbpA and symplekin form a complex in kidney and intestinal epithelial cells that can be immunoprecipitated and that exists in the nucleus. The interaction between ZONAB/DbpA and symplekin can be reconstituted with recombinant proteins. In reporter gene assays in which ZONAB/DbpA functions as a repressor, symplekin functionally interacts with ZONAB/DbpA, indicating that symplekin can also promote transcriptional repression. RNAi experiments indicate that symplekin depletion reduces the nuclear accumulation and the transcriptional activity of ZONAB/DbpA in colon adenocarcinoma cells, resulting in inhibition of proliferation and reduced expression of the ZONAB/DbpA-target gene cyclin D1. Our data thus indicate that symplekin and ZONAB/DbpA cooperate in the regulation of transcription, and that they promote epithelial proliferation and cyclin D1 expression.
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Affiliation(s)
- Emma Kavanagh
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, UK
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76
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Paul SM, Palladino MJ, Beitel GJ. A pump-independent function of the Na,K-ATPase is required for epithelial junction function and tracheal tube-size control. Development 2007; 134:147-55. [PMID: 17164420 PMCID: PMC1955469 DOI: 10.1242/dev.02710] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The heterodimeric Na,K-ATPase has been implicated in vertebrate and invertebrate epithelial cell junctions, morphogenesis and oncogenesis, but the mechanisms involved are unclear. We previously showed that the Drosophila Na,K-ATPase is required for septate junction (SJ) formation and that of the three beta-subunit loci, only Nrv2 isoforms support epithelial SJ barrier function and tracheal tube-size control. Here we show that Nrv1 is endogenously co-expressed with Nrv2 in the epidermis and tracheal system, but Nrv1 has a basolateral localization and appears to be excluded from the Nrv2-containing SJs. When the normally neuronal Nrv3 is expressed in epithelial cells, it does not associate with SJs. Thus, the beta-subunit is a key determinant of Na,K-ATPase subcellular localization as well as function. However, localization of the Na,K-ATPase to SJs is not sufficient for junctional activity because although several Nrv2/Nrv3 chimeric beta-subunits localize to SJs, only those containing the extracellular domain of Nrv2 have junctional activity. Junctional activity is also specific to different alpha-subunit isoforms, with only some isoforms from the major alpha-subunit locus being able to provide full barrier function and produce normal tracheal tubes. Importantly, mutations predicted to inactivate ATPalpha catalytic function do not compromise junctional activity, demonstrating that the Drosophila Na,K-ATPase has an ion-pump-independent role in junction formation and tracheal morphogenesis. These results define new functions for the intensively studied Na,K-ATPase. Strikingly, the rat alpha1 isoform has full junctional activity and can rescue Atpalpha-null mutants to viability, suggesting that the Na,K-ATPase has an evolutionarily conserved role in junction formation and function.
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Affiliation(s)
- Sarah M. Paul
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208, USA
| | - Michael J. Palladino
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
- Department of Pharmacology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Greg J. Beitel
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, IL 60208, USA
- *Author for correspondence (e-mail: )
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77
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González-Mariscal L, Lechuga S, Garay E. Role of tight junctions in cell proliferation and cancer. ACTA ACUST UNITED AC 2007; 42:1-57. [PMID: 17502225 DOI: 10.1016/j.proghi.2007.01.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The acquisition of a cancerous phenotype by epithelial cells involves the disruption of intercellular adhesions. The reorganization of the E-cadherin/beta-catenin complex in adherens junctions during cell transformation is widely recognized. Instead the implication of tight junctions (TJs) in this process is starting to be unraveled. The aim of this article is to review the role of TJ proteins in cell proliferation and cancer.
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Affiliation(s)
- Lorenza González-Mariscal
- Center for Research and Advanced Studies (Cinvestav), Department of Physiology, Biophysics and Neuroscience, Ave. Instituto Politécnico Nacional 2508, México, DF 07360, México.
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78
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Flores-Benítez D, Ruiz-Cabrera A, Flores-Maldonado C, Shoshani L, Cereijido M, Contreras RG. Control of tight junctional sealing: role of epidermal growth factor. Am J Physiol Renal Physiol 2007; 292:F828-36. [PMID: 17077385 DOI: 10.1152/ajprenal.00369.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Epithelia can adjust the permeability of their paracellular permeation route to physiological requirements, pathological conditions, and pharmacological challenges. This is reflected by a transepithelial electrical resistance (TER) ranging from a few tenth to several thousands Ω·cm2, depending on the degree of sealing of the tight junction (TJ). The present work is part of an effort to understand the causes and mechanisms underlying these adaptations. We observed that an extract of human urine (hDLU) increases TER in a concentration- and time-dependent manner and is more effective when added from the basolateral side of cultured monolayers of Madin-Darby canine kidney cells than from the apical one. We found that its main TER-increasing component is epidermal growth factor (hEGF), as depletion of this peptide with specific antibodies, or inhibition of its receptor with PD153035, abolishes its effect. Since the permeability of the TJ depends on the expression of several species of membrane proteins, chiefly claudins, we explored whether hDLU can affect five members of the claudin family, the three known members of the ZO family, and occludin. EGF present in hDLU decreases the content of claudins-1 and -2 as well as delocalizes them from the TJ and increases the content of claudin-4. As expected from the fact that the degree of sealing of the TJ must be a physiologically regulated parameter, besides of hEGF, we also found that hDLU appears to contain also other components that decrease TER, claudin-4 and -7, and that seem to act with different kinetics than the TER-increasing ones.
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Affiliation(s)
- D Flores-Benítez
- Department of Physiology, Universidad Nacional Autónoma de México, México
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79
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Gravotta D, Deora A, Perret E, Oyanadel C, Soza A, Schreiner R, Gonzalez A, Rodriguez-Boulan E. AP1B sorts basolateral proteins in recycling and biosynthetic routes of MDCK cells. Proc Natl Acad Sci U S A 2007; 104:1564-9. [PMID: 17244703 PMCID: PMC1785260 DOI: 10.1073/pnas.0610700104] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The epithelial-specific adaptor AP1B sorts basolateral proteins, but the trafficking routes where it performs its sorting role remain controversial. Here, we used an RNAi approach to knock down the medium subunit of AP1B (mu1B) in the prototype epithelial cell line Madin-Darby canine kidney (MDCK). Mu1B-knocked down MDCK cells displayed loss of polarity of several endogenous and exogenous basolateral markers transduced via adenovirus vectors, but exhibited normal polarity of apical markers. We chose two well characterized basolateral protein markers, the transferrin receptor (TfR) and the vesicular stomatitis virus G protein, to study the sorting role of AP1B. A surface-capture assay introduced here showed that mu1B-knocked down MDCK cells plated on filters at confluency and cultured for 4.5 d, sorted TfR correctly in the biosynthetic route but incorrectly in the recycling route. In contrast, these same cells missorted vesicular stomatitis virus G apically in the biosynthetic route. Strikingly, recently confluent MDCK cells (1-3 d) displayed AP1B-dependence in the biosynthetic route of TfR, which decreased with additional days in culture. Sucrose density gradient analysis detected AP1B predominantly in TfR-rich endosomal fractions in MDCK cells confluent for 1 and 4 d. Our results are consistent with the following model: AP1B sorts basolateral proteins in both biosynthetic and recycling routes of MDCK cells, as a result of its predominant functional localization in recycling endosomes, which constitute a post-Golgi station in the biosynthetic route of some plasma membrane proteins. TfR utilizes a direct route from Golgi to basolateral membrane that is established as the epithelial monolayer matures.
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Affiliation(s)
- Diego Gravotta
- *Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021
| | - Ami Deora
- *Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021
| | - Emilie Perret
- *Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021
| | - Claudia Oyanadel
- Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile; and
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - Andrea Soza
- Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile; and
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - Ryan Schreiner
- *Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021
| | - Alfonso Gonzalez
- Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, and Centro de Regulación Celular y Patología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 6510260 Santiago, Chile; and
- Millennium Institute for Fundamental and Applied Biology, 7780344 Santiago, Chile
| | - Enrique Rodriguez-Boulan
- *Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021
- To whom correspondence should be addressed. E-mail:
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80
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Vagin O, Tokhtaeva E, Sachs G. The role of the beta1 subunit of the Na,K-ATPase and its glycosylation in cell-cell adhesion. J Biol Chem 2006; 281:39573-87. [PMID: 17052981 DOI: 10.1074/jbc.m606507200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Based on recent data showing that overexpression of the Na,K-ATPase beta(1) subunit increased cell-cell adhesion of nonpolarized cells, we hypothesized that the beta(1) subunit can also be involved in the formation of cell-cell contacts in highly polarized epithelial cells. In support of this hypothesis, in Madin-Darby canine kidney (MDCK) cells, the Na,K-ATPase alpha(1) and beta(1) subunits were detected as precisely co-localized with adherens junctions in all stages of the monolayer formation starting from the initiation of cell-cell contact. The Na,K-ATPase and adherens junction protein, beta-catenin, stayed partially co-localized even after their internalization upon disruption of intercellular contacts by Ca(2+) depletion of the medium. The Na,K-ATPase subunits remained co-localized with the adherens junctions after detergent treatment of the cells. In contrast, the heterodimer formed by expressed unglycosylated Na,K-ATPase beta(1) subunit and the endogenous alpha(1) subunit was easily dissociated from the adherens junctions and cytoskeleton by the detergent extraction. The MDCK cell line in which half of the endogenous beta(1) subunits in the lateral membrane were substituted by unglycosylated beta(1) subunits displayed a decreased ability to form cell-to-cell contacts. Incubation of surface-attached MDCK cells with an antibody against the extracellular domain of the Na,K-ATPase beta(1) subunit specifically inhibited cell-cell contact formation. We conclude that the Na,K-ATPase beta(1) subunit is involved in the process of intercellular adhesion and is necessary for association of the heterodimeric Na,K-ATPase with the adherens junctions. Further, normal glycosylation of the Na,K-ATPase beta(1) subunit is essential for the stable association of the pump with the adherens junctions and plays an important role in cell-cell contact formation.
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Affiliation(s)
- Olga Vagin
- Department of Physiology, School of Medicine, UCLA and Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California 90073, USA
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81
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Jaitovich AA, Bertorello AM. Na+, K+-ATPase: An Indispensable Ion Pumping-Signaling Mechanism Across Mammalian Cell Membranes. Semin Nephrol 2006; 26:386-92. [PMID: 17071332 DOI: 10.1016/j.semnephrol.2006.07.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Na(+), K(+)-adenosine triphosphatase is a ubiquitous enzyme present in higher eukaryotes responsible for the maintenance of ionic gradients across the plasma membrane. It creates appropriate conditions for critical cellular processes such as secondary transport of solutes and water, for pH regulation, and also for creating an electrical potential that gives singular qualities to excitable cells. It also served as a platform for a higher level of cellular complexity because many important signaling networks appear to be downstream events of the pump's function. Renal physiology and pathology are affected significantly by its presence, and it seems that both molecular and pharmacologic manipulations of its action can create different venues to deal with diverse disease states.
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Affiliation(s)
- A Ariel Jaitovich
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL, USA.
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82
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Larre I, Ponce A, Fiorentino R, Shoshani L, Contreras RG, Cereijido M. Contacts and cooperation between cells depend on the hormone ouabain. Proc Natl Acad Sci U S A 2006; 103:10911-6. [PMID: 16835298 PMCID: PMC1544148 DOI: 10.1073/pnas.0604496103] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Indexed: 12/14/2022] Open
Abstract
Cell adhesion is a crucial step in proliferation, differentiation, migration, apoptosis, and metastasis. In previous works we have shown that cell adhesion is modulated by ouabain, a highly specific inhibitor of Na+,K+-ATPase, recently found to be a hormone. In the present work we pursue the investigation of the effect of ouabain on a special type of cell-cell interaction: the rescue of ouabain-sensitive MDCK cells (W) by ouabain-resistant cells (R). In cultured monolayers of pure W cells, ouabain triggers the "P-->A mechanism" (from pump/adhesion) consisting of a cascade of phosphorylations that retrieves adhesion-associated molecules occludin and beta-catenin and results in detachment of the cell. When W cells are instead cocultured with R cells, the P-->A reaction is blocked, and W cells are rescued. Furthermore, in these R/W cocultures ouabain promotes cell-cell communication by means of gap junctions by specifically enhancing the expression of connexin 32 and addressing this molecule to the plasma membrane. Ouabain also promotes the internalization of the beta-subunit of the Na+,K+-ATPase. These observations open the possibility that the crucial processes mentioned at the beginning would be under the control of the hormone ouabain.
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Affiliation(s)
- Isabel Larre
- Department of Physiology, Biophysics, and Neurosciences, Centro de Investigación y de Estudios Avanzados, México City, DF 07300, México
| | - Arturo Ponce
- Department of Physiology, Biophysics, and Neurosciences, Centro de Investigación y de Estudios Avanzados, México City, DF 07300, México
| | - Rosana Fiorentino
- Department of Physiology, Biophysics, and Neurosciences, Centro de Investigación y de Estudios Avanzados, México City, DF 07300, México
| | - Liora Shoshani
- Department of Physiology, Biophysics, and Neurosciences, Centro de Investigación y de Estudios Avanzados, México City, DF 07300, México
| | - Rubén G. Contreras
- Department of Physiology, Biophysics, and Neurosciences, Centro de Investigación y de Estudios Avanzados, México City, DF 07300, México
| | - Marcelino Cereijido
- Department of Physiology, Biophysics, and Neurosciences, Centro de Investigación y de Estudios Avanzados, México City, DF 07300, México
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83
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Abstract
The epithelial tight junction (TJ) has three major functions. As a "gate," it serves as a regulatory barrier separating and maintaining biological fluid compartments of different composition. As a "fence," it generates and maintains the apicobasal polarity of cells that form the confluent epithelium. Finally, the TJ proteins form a trafficking and signaling platform that regulates cell growth, proliferation, differentiation, and dedifferentiation. Six examples are selected that illustrate the emerging link between TJ dysfunction and kidney disease. First, the glomerular slit diaphragm (GSD) is evolved, in part, from the TJ and, on maturation, exhibits all three functions of the TJ. GSD dysfunction leads to proteinuria and, in some instances, podocyte dedifferentiation and proliferation. Second, accumulating evidence supports epithelial-mesenchymal transformation (EMT) as a major player in renal fibrosis, the final common pathway that leads to end-stage renal failure. EMT is characterized by a loss of cell-cell contact and apicobasal polarity, which are hallmarks of TJ dysfunction. Third, in autosomal dominant polycystic kidney disease, mutations of the polycystins may disrupt their known interactions with the apical junction complex, of which the TJ is a major component. This can lead to disturbances in epithelial polarity regulation with consequent abnormal tubulogenesis and cyst formation. Fourth, evidence for epithelial barrier and polarity dysregulation in the pathogenesis of ischemic acute renal failure will be summarized. Fifth, the association between mutations of paracellin-1, the first TJ channel identified, and clinical disorders of magnesium and calcium wasting and bovine renal fibrosis will be used to highlight an integral TJ protein that can serve multiple TJ functions. Finally, the role of WNK4 protein kinase in shunting chloride across the TJ of the distal nephron will be addressed.
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Affiliation(s)
- David B N Lee
- Division of Nephrology, Veterans Affairs Greater Los Angeles Healthcare System, California, USA.
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84
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Aijaz S, Balda MS, Matter K. Tight junctions: molecular architecture and function. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 248:261-98. [PMID: 16487793 DOI: 10.1016/s0074-7696(06)48005-0] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tight junctions are the most apical component of the epithelial junctional complex and are crucial for the formation and functioning of epithelial and endothelial barriers. They regulate selective diffusion of ions and solutes along the paracellular pathway and restrict apical/basolateral intramembrane diffusion of lipids. Research over the past years provided much insight into the molecular composition of tight junctions, and we are starting to understand the mechanisms that permit selective paracellular diffusion. Moreover, a complex network of proteins has been identified at tight junctions that is based on cytoskeleton-linked adaptors that recruit and thereby often regulate different types of signaling components that regulate epithelial proliferation, differentiation, and polarization.
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Affiliation(s)
- Saima Aijaz
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, United Kingdom
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Matter K, Aijaz S, Tsapara A, Balda MS. Mammalian tight junctions in the regulation of epithelial differentiation and proliferation. Curr Opin Cell Biol 2005; 17:453-8. [PMID: 16098725 DOI: 10.1016/j.ceb.2005.08.003] [Citation(s) in RCA: 235] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Accepted: 08/02/2005] [Indexed: 12/24/2022]
Abstract
Tight junctions are important for the permeability properties of epithelial and endothelial barriers as they restrict diffusion along the paracellular space. Recent observations have revealed that tight junctions also function in the regulation of epithelial proliferation and differentiation. They harbour evolutionarily conserved protein complexes that regulate polarisation and junction assembly. Tight junctions also recruit signalling proteins that participate in the regulation of cell proliferation and differentiation. These signalling proteins include components that affect established signalling cascades and dual localisation proteins that can associate with junctions as well as travel to the nucleus where they regulate gene expression.
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Affiliation(s)
- Karl Matter
- Division of Cell Biology, Institute of Ophthalmology, University College London, Bath Street, London, EC1V 9EL, UK.
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86
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Chen JQ, Contreras RG, Wang R, Fernandez SV, Shoshani L, Russo IH, Cereijido M, Russo J. Sodium/potasium ATPase (Na+, K+-ATPase) and ouabain/related cardiac glycosides: a new paradigm for development of anti- breast cancer drugs? Breast Cancer Res Treat 2005; 96:1-15. [PMID: 16322895 DOI: 10.1007/s10549-005-9053-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 08/11/2005] [Indexed: 11/30/2022]
Abstract
Prolonged exposure to 17beta-estradiol (E2) is a key etiological factor for human breast cancer. The biological effects and carcinogenic effects of E2 are mediated via estrogen receptors (ERs), ERalpha and ERbeta. Anti-estrogens, e.g. tamoxifen, and aromatase inhibitors have been used to treat ER-positive breast cancer. While anti-estrogen therapy is initially successful, a major problem is that most tumors develop resistance and the disease ultimately progresses, pointing to the need of developing alternative drugs targeting to other critical targets in breast cancer cells. We have identified that Na+, K+-ATPase, a plasma membrane ion pump, has unique/valuable properties that could be used as a potentially important target for breast cancer treatment: (a) it is a key player of cell adhesion and is involved in cancer progression; (b) it serves as a versatile signal transducer and is a target for a number of hormones including estrogens and (d) its aberrant expression and activity are implicated in the development and progression of breast cancer. There are several lines of evidence indicating that ouabain and related digitalis (the potent inhibitors of Na+, K+-ATPase) possess potent anti-breast cancer activity. While it is not clear how the suggested anti-cancer activity of these drugs work, several observations point to ouabain and digitalis as being potential ER antagonists. We critically reviewed many lines of evidence and postulated a novel concept that Na+, K+-ATPase in combination with ERs could be important targets of anti-breast cancer drugs. Modulators, e.g. ouabain and related digitalis could be useful to develop valuable anti-breast cancer drugs as both Na+, K+-ATPase inhibitors and ER antagonists.
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Affiliation(s)
- Jin-Qiang Chen
- Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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87
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Rodriguez-Boulan E, Kreitzer G, Müsch A. Organization of vesicular trafficking in epithelia. Nat Rev Mol Cell Biol 2005; 6:233-47. [PMID: 15738988 DOI: 10.1038/nrm1593] [Citation(s) in RCA: 490] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Experiments using mammalian epithelial cell lines have elucidated biosynthetic and recycling pathways for apical and basolateral plasma-membrane proteins, and have identified components that guide apical and basolateral proteins along these pathways. These components include apical and basolateral sorting signals, adaptors for basolateral signals, and docking and fusion proteins for vesicular trafficking. Recent live-cell-imaging studies provide a real-time view of sorting processes in epithelial cells, including key roles for actin, microtubules and motors in the organization of post-Golgi trafficking.
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Affiliation(s)
- Enrique Rodriguez-Boulan
- Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Avenue, New York, New York 10021, USA.
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88
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Rodriguez-Boulan E, Müsch A, Le Bivic A. Epithelial trafficking: new routes to familiar places. Curr Opin Cell Biol 2005; 16:436-42. [PMID: 15261677 DOI: 10.1016/j.ceb.2004.06.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Research carried out in mammalian epithelial cell systems over the past 25 years has delineated pathways and sorting signals involved in polarized delivery of plasma membrane proteins. Recently some progress has been made in the identification of mechanisms underlying this polarized trafficking and in the visualization of trafficking routes in live cells. A promising area of research is the study of trafficking functions of novel polarity genes identified in Drosophila and Caenorhabditis elegans.
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Affiliation(s)
- Enrique Rodriguez-Boulan
- Margaret Dyson Vision Research Institute, Weill Medical College of Cornell University, 1300 York Ave, New York, New York 10021, USA.
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89
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Shoshani L, Contreras RG, Roldán ML, Moreno J, Lázaro A, Balda MS, Matter K, Cereijido M. The polarized expression of Na+,K+-ATPase in epithelia depends on the association between beta-subunits located in neighboring cells. Mol Biol Cell 2004; 16:1071-81. [PMID: 15616198 PMCID: PMC551474 DOI: 10.1091/mbc.e04-03-0267] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The polarized distribution of Na+,K+-ATPase plays a paramount physiological role, because either directly or through coupling with co- and countertransporters, it is responsible for the net movement of, for example, glucose, amino acids, Ca2+, K+, Cl-, and CO3H- across the whole epithelium. We report here that the beta-subunit is a key factor in the polarized distribution of this enzyme. 1) Madin-Darby canine kidney (MDCK) cells (epithelial from dog kidney) express the Na+,K+-ATPase over the lateral side, but not on the basal and apical domains, as if the contact with a neighboring cell were crucial for the specific membrane location of this enzyme. 2) MDCK cells cocultured with other epithelial types (derived from human, cat, dog, pig, monkey, rabbit, mouse, hamster, and rat) express the enzyme in all (100%) homotypic MDCK/MDCK borders but rarely in heterotypic ones. 3) Although MDCK cells never express Na+,K+-ATPase at contacts with Chinese hamster ovary (CHO) cells, they do when CHO cells are transfected with beta1-subunit from the dog kidney (CHO-beta). 4) This may be attributed to the adhesive property of the beta1-subunit, because an aggregation assay using CHO (mock-transfected) and CHO-beta cells shows that the expression of dog beta1-subunit in the plasma membrane does increase adhesiveness. 5) This adhesiveness does not involve adherens or tight junctions. 6) Transfection of beta1-subunit forces CHO-beta cells to coexpress endogenous alpha-subunit. Together, our results indicate that MDCK cells express Na+,K+-ATPase at a given border provided the contacting cell expresses the dog beta1-subunit. The cell-cell interaction thus established would suffice to account for the polarized expression and positioning of Na+,K+-ATPase in epithelial cells.
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Affiliation(s)
- Liora Shoshani
- Center for Research and Advanced Studies, Department of Physiology, Biophysics, and Neurosciences, México City 07300, México.
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