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Gene Review

Ocln  -  occludin

Mus musculus

Synonyms: AI503564, Occludin, Ocl
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Disease relevance of Ocln


High impact information on Ocln

  • Both cell lines maintained a luminal epithelial phenotype as evidenced by expression of the tight junction proteins, claudin-1 and occludin, and by generation of a high transepithelial electrical resistance on semipermeable filters [5].
  • Alterations in epithelial permeability were correlated with TJ structure and the state of phosphorylation of occludin. iIEL in vivo reconstitution experiments were used to identify the iIELs required to maintain epithelial permeability and TJ integrity [6].
  • Leaky epithelium in gammadelta(+) iIEL-deficient mice was associated with the absence of phosphorylation of serine residues of occludin and lack of claudin 3 and zona occludens-1 proteins in TJ complexes [6].
  • The examination of tight junction proteins revealed an absence of occludin, which did not prevent the diffusion of subcutaneously injected tracer (approximately 600 D) toward the skin surface [7].
  • These findings indicate that there are as yet unidentified TJ integral membrane protein(s) which can form strand structures, recruit ZO-1, and function as a barrier without occludin [8].

Chemical compound and disease context of Ocln

  • In addition, GET-1 brains exhibited more Evans blue extravasation and showed decreased endothelial occludin expression after MCAO, correlating with higher brain water content and increased cerebral edema [9].

Biological context of Ocln


Anatomical context of Ocln

  • Occludin is the only known integral membrane protein of tight junctions (TJs), and is now believed to be directly involved in the barrier and fence functions of TJs [8].
  • Freeze fracture analyses indicated no significant differences in number or morphology of TJ strands between wild-type and occludin-deficient epithelial cells [8].
  • To investigate mechanisms regulating the timing of blastocyst formation, we have examined the dynamics of expression of occludin, an integral membrane protein of the TJ [10].
  • During mouse skin development, this peculiar distribution of occludin in the epidermis appeared when the periderm, a simple epithelium bearing typical occludin-based tight junctions, was sloughed off at embryonic day 16.5 of gestation [13].
  • In hair follicles, occludin and ZO-1 were colocalized at cell-cell borders in Henle's layer and the cornifying cuticle of the inner root sheath [13].

Associations of Ocln with chemical compounds

  • Among numerous components of this fraction, only a broad silver-stained band approximately 22 kD was detected with the occludin band through 4 M guanidine-HCl extraction as well as sonication followed by stepwise sucrose density gradient centrifugation [14].
  • Immediately after assembly and before cavitation, occludin localised at the TJ site switches from a Triton X-100-soluble to -insoluble form indicative of actin cytoskeletal and/or membrane anchorage [10].
  • Occludin membrane assembly is dependent upon prior E-cadherin-mediated cell-cell adhesion and is sensitive to brefeldin A, an inhibitor of Golgi-to-membrane transport [10].
  • From our data we conclude that differences in structure between avian and mammalian occludin do not account for the observed paradoxical increase in mannitol flux [15].
  • Treatment with a GJIC blocker, 18 beta-glycyrrhetinic acid, resulted in decreases of occludin and claudin-1 at cell borders in the stable transfectants [16].

Physical interactions of Ocln


Co-localisations of Ocln

  • The myc-tagged claudin-1 precisely colocalized with both occludin and ZO-1 at cell-cell contact sites, indicating that exogenous claudin-1 was properly targeted to the TJs [18].

Regulatory relationships of Ocln


Other interactions of Ocln

  • Occludin and 18 distinct members of the claudin family are tetra-span transmembrane proteins that are localized in cell-specific tight junctions (TJs) [15].
  • The localization of ZO-1, occludin and claudin-6 appeared normal in mutant epithelial cells, indicating that cingulin is not required for their junctional recruitment [20].
  • In transient wild-type Cx32 transfectants, immunocytochemistry revealed that endogenous occludin was in part localized at cell borders, where it was colocalized with Cx32, whereas neither was detected in parental cells [16].
  • In rat liver lobules at 24 h after thioacetamide (TAA) treatment, where some IL-1beta-positive non-parenchymal cells existed, disappearance of connexin32-positive spots at cell borders of the hepatocytes and increases of claudin-2 and occludin immunoreactivities in bile canalicular regions were observed [21].
  • Although both occludin and ZO-1 largely partitioned with the CSK fraction in BMEC, they were found predominantly in the soluble fraction of bEND.3 cells, and claudin-5 was found associated equally with both fractions in BMEC and bEND.3 cells [22].

Analytical, diagnostic and therapeutic context of Ocln

  • Immunofluorescence microscopy and ultrathin section electron microscopy revealed that polarized epithelial (visceral endoderm-like) cells were differentiated to delineate EBs not only from wild-type but also from occludin-deficient ES cells [8].
  • Occludin mRNA and protein are detectable throughout cleavage by RT-PCR and immunoblotting, respectively, indicating that timing of membrane assembly is not controlled by expression alone [10].
  • Confocal microscopy of intact embryos and synchronised cell clusters revealed that occludin first assembles at the apicolateral membrane contact site between nascent trophectoderm cells usually during the early 32-cell stage, just prior to the time of blastocoele cavitation [10].
  • Immunoblotting detected all of these molecules in isolated epidermis, but the occludin/ZO-1 (or occludin/ZO-2) ratio was significantly lower than that in cultured simple epithelial cells [13].
  • Ouabain treatment (up to 6 h) or culture in K(+)-free medium (up to 6 h) resulted in the appearance of a discontinuous ZO-1 protein distribution and a loss of occludin immunofluorescence [23].


  1. Thalidomide treatment reduces the alteration of paracellular barrier function in mice ileum during experimental colitis. Mazzon, E., Cuzzocrea, S. Shock (2006) [Pubmed]
  2. Increased iNOS activity is essential for hepatic epithelial tight junction dysfunction in endotoxemic mice. Han, X., Fink, M.P., Uchiyama, T., Yang, R., Delude, R.L. Am. J. Physiol. Gastrointest. Liver Physiol. (2004) [Pubmed]
  3. Epithelial transport and barrier function in occludin-deficient mice. Schulzke, J.D., Gitter, A.H., Mankertz, J., Spiegel, S., Seidler, U., Amasheh, S., Saitou, M., Tsukita, S., Fromm, M. Biochim. Biophys. Acta (2005) [Pubmed]
  4. Disruption of paracellular sealing is an early event in acute caerulein-pancreatitis. Schmitt, M., Klonowski-Stumpe, H., Eckert, M., Lüthen, R., Häussinger, D. Pancreas (2004) [Pubmed]
  5. Isolation, immortalization, and characterization of a human breast epithelial cell line with stem cell properties. Gudjonsson, T., Villadsen, R., Nielsen, H.L., Rønnov-Jessen, L., Bissell, M.J., Petersen, O.W. Genes Dev. (2002) [Pubmed]
  6. Intraepithelial gammadelta(+) Lymphocytes Maintain the Integrity of Intestinal Epithelial Tight Junctions in Response to Infection. Dalton, J.E., Cruickshank, S.M., Egan, C.E., Mears, R., Newton, D.J., Andrew, E.M., Lawrence, B., Howell, G., Else, K.J., Gubbels, M.J., Striepen, B., Smith, J.E., White, S.J., Carding, S.R. Gastroenterology (2006) [Pubmed]
  7. The epidermal barrier function is dependent on the serine protease CAP1/Prss8. Leyvraz, C., Charles, R.P., Rubera, I., Guitard, M., Rotman, S., Breiden, B., Sandhoff, K., Hummler, E. J. Cell Biol. (2005) [Pubmed]
  8. Occludin-deficient embryonic stem cells can differentiate into polarized epithelial cells bearing tight junctions. Saitou, M., Fujimoto, K., Doi, Y., Itoh, M., Fujimoto, T., Furuse, M., Takano, H., Noda, T., Tsukita, S. J. Cell Biol. (1998) [Pubmed]
  9. Endothelin-1 overexpression leads to further water accumulation and brain edema after middle cerebral artery occlusion via aquaporin 4 expression in astrocytic end-feet. Lo, A.C., Chen, A.Y., Hung, V.K., Yaw, L.P., Fung, M.K., Ho, M.C., Tsang, M.C., Chung, S.S., Chung, S.K. J. Cereb. Blood Flow Metab. (2005) [Pubmed]
  10. Post-translational control of occludin membrane assembly in mouse trophectoderm: a mechanism to regulate timing of tight junction biogenesis and blastocyst formation. Sheth, B., Moran, B., Anderson, J.M., Fleming, T.P. Development (2000) [Pubmed]
  11. Regulation of tight junctions during the epithelium-mesenchyme transition: direct repression of the gene expression of claudins/occludin by Snail. Ikenouchi, J., Matsuda, M., Furuse, M., Tsukita, S. J. Cell. Sci. (2003) [Pubmed]
  12. Down-regulation of survival signaling through MAPK and Akt in occludin-deficient mouse hepatocytes in vitro. Murata, M., Kojima, T., Yamamoto, T., Go, M., Takano, K., Osanai, M., Chiba, H., Sawada, N. Exp. Cell Res. (2005) [Pubmed]
  13. Subcellular distribution of tight junction-associated proteins (occludin, ZO-1, ZO-2) in rodent skin. Morita, K., Itoh, M., Saitou, M., Ando-Akatsuka, Y., Furuse, M., Yoneda, K., Imamura, S., Fujimoto, K., Tsukita, S. J. Invest. Dermatol. (1998) [Pubmed]
  14. Claudin-1 and -2: novel integral membrane proteins localizing at tight junctions with no sequence similarity to occludin. Furuse, M., Fujita, K., Hiiragi, T., Fujimoto, K., Tsukita, S. J. Cell Biol. (1998) [Pubmed]
  15. Inducible expression of claudin-1-myc but not occludin-VSV-G results in aberrant tight junction strand formation in MDCK cells. McCarthy, K.M., Francis, S.A., McCormack, J.M., Lai, J., Rogers, R.A., Skare, I.B., Lynch, R.D., Schneeberger, E.E. J. Cell. Sci. (2000) [Pubmed]
  16. Cx32 formation and/or Cx32-mediated intercellular communication induces expression and function of tight junctions in hepatocytic cell line. Kojima, T., Spray, D.C., Kokai, Y., Chiba, H., Mochizuki, Y., Sawada, N. Exp. Cell Res. (2002) [Pubmed]
  17. The tight junction protein occludin and the adherens junction protein alpha-catenin share a common interaction mechanism with ZO-1. Müller, S.L., Portwich, M., Schmidt, A., Utepbergenov, D.I., Huber, O., Blasig, I.E., Krause, G. J. Biol. Chem. (2005) [Pubmed]
  18. Claudin-1 contributes to the epithelial barrier function in MDCK cells. Inai, T., Kobayashi, J., Shibata, Y. Eur. J. Cell Biol. (1999) [Pubmed]
  19. Perturbation of the tight junction permeability barrier by occludin loop peptides activates beta-catenin/TCF/LEF-mediated transcription. Vietor, I., Bader, T., Paiha, K., Huber, L.A. EMBO Rep. (2001) [Pubmed]
  20. Disruption of the cingulin gene does not prevent tight junction formation but alters gene expression. Guillemot, L., Hammar, E., Kaister, C., Ritz, J., Caille, D., Jond, L., Bauer, C., Meda, P., Citi, S. J. Cell. Sci. (2004) [Pubmed]
  21. IL-1beta regulates expression of Cx32, occludin, and claudin-2 of rat hepatocytes via distinct signal transduction pathways. Yamamoto, T., Kojima, T., Murata, M., Takano, K., Go, M., Chiba, H., Sawada, N. Exp. Cell Res. (2004) [Pubmed]
  22. Culture of murine brain microvascular endothelial cells that maintain expression and cytoskeletal association of tight junction-associated proteins. Song, L., Pachter, J.S. In Vitro Cell. Dev. Biol. Anim. (2003) [Pubmed]
  23. Na+/K+ -ATPase regulates tight junction formation and function during mouse preimplantation development. Violette, M.I., Madan, P., Watson, A.J. Dev. Biol. (2006) [Pubmed]
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