PKCalpha‐mediated signaling in regulating adherens junction integrity

Abstract

The aim of this study was to determine the mechanism of protein kinase C‐α (PKCα)‐mediated disruption of adherens junctions (AJs). We have shown that depletion of PKCα in human microvascular endothelial cells reduces the thrombin‐induced permeability increase by 50%, as assessed by change in transendothelial resistance. PKCα‐depleted endothelial cells formed fewer interendothelial gaps and retained more vascular endothelial (VE)‐cadherin at AJs after thrombin stimulation compared to control cells. VE‐cadherin stability at AJs has been shown to be dependent on p120‐catenin (p120) binding. Dissociation of p120 from VE‐cadherin results in VE‐cadherin internalization and disassembly of AJs. Since activation of PKCα after thrombin stimulation leads to changes in phosphorylation of p120 in endothelial cells, we tested the hypothesis that PKCα‐mediated phosphorylation of p120 causes dissociation of p120 from VE‐cadherin, subsequent disassembly of AJs and increased permeability of the endothelial barrier. Our data demonstrate that thrombin stimulation of endothelial cells results in translocation of PKCα to AJs and interaction with p120. Furthermore, the level of p120 remains unchanged at AJs in PKCα‐depleted cells after thrombin stimulation, supporting our hypothesis that PKCα may induce p120 dissociation from VE‐cadherin, resulting in AJ disassembly.Supported by NIH Grants HL045638 and HL007829