Catenins and zonula occludens-1 form a complex during early stages in the assembly of tight junctions.

摘要: We characterized the role of E-cadherin adhesion system in formation epithelial tight junctions using calcium switch model. In MDCK cells cultured low (micromolar) levels, junctional protein Zonula Occludens-1 (ZO-1) is distributed intracellularly granular clusters, larger which codistribute with E-cadherin. Two hours after activation by transfer to normal (1.8 mM) ZO-1 dramatically redistributed cell surface, where it localized regions rich Immunoprecipitation antibodies extracts from kept and 2 h shifting 1.8 mM Ca2+ demonstrated association alpha-, beta-, gamma-catenins. was not detected immunoprecipitates but found beta-catenin that excluded ZO-1, suggesting binding catenins may weaken interaction these proteins Immunofluorescence immunoelectron microscopy confirmed a close at 0 switch. 48 switch, upon complete polarization epithelium, most had segregated lateral formed distinct, separate apical ring. The ZO-1-catenin complex fully polarized monolayers. permanently transformed Moloney sarcoma virus, expresses levels E-cadherin, displayed clusters cytoplasmic granules very little this surface. Upon transfection into virus-MDCK cells, E-cadherin-rich plasma membrane later failed segregate mature junctions. Our experiments suggest participate mobilization cytosol surface early development neoplastic transformation block junctions, either decreasing or preventing late event: segregation junction zonula adherens.