VE-cadherin-p120 interaction is required for maintenance of endothelial barrier function

Abstract

Interaction of p120 with juxtamembrane domain (JMD) of VE-cadherin has been implicated in regulation of endothelial cell-cell adhesion. We used a number of approaches to alter the level of p120 available for binding to VE-cadherin as a means to investigate the role of p120-VE-cadherin interaction in regulation of barrier function in confluent endothelial monolayers. Expression of an epitope-tagged fragment corresponding to JMD of VE-cadherin resulted in a decrease in endothelial barrier function as assessed by changes in albumin clearance and electrical resistance. Binding of JMD-Flag to p120 resulted in a decreased level of p120. In addition to decreasing p120 level, expression of JMD also decreased level of VE-cadherin. Expression of JMD also caused an increase in MLC phosphorylation and rearrangement of actin cytoskeleton, which, coupled with decreased cadherin, can contribute to loss of barrier function. Reducing p120 by siRNA resulted in a decrease in VE-cadherin, whereas increasing the level of p120 increased the level of VE-cadherin, demonstrating that p120 regulates the level of VE-cadherin. Overexpression of p120 was, however, associated with decreased barrier function and rearrangement of the actin cytoskeleton. Interestingly, expression of p120 was able to inhibit thrombin-induced increases in MLC phosphorylation, suggesting that p120 inhibits activation of Rho/Rho kinase pathway in endothelial cells. Excess p120 also prevented JMD-induced increases in MLC phosphorylation, correlating this phosphorylation with Rho/Rho kinase pathway. These findings show p120 plays a major role in regulating endothelial barrier function, as either a decrease or increase of p120 resulted in disruption of permeability across cell monolayers.

Integrin β1 controls VE-cadherin localization and blood vessel stability

“…The interaction between VE-cadherin and p120 d-catenin prevents clathrin-dependent endocytosis of the cadherin and is essential for endothelial barrier function [26][27][28][29] . In control retinal vessels, anti-p120 immunosignal was visible at endothelial cell-cell contacts and overlapped with anti-VE-cadherin staining (Fig.…”

“…Although the binding of p120 inhibits VE-cadherin internalization, d-catenin is also a negative regulator of the Rho/Rho-kinase pathway and myosin light chain (MLC) phosphorylation in ECs 26,28 . VE-cadherin promotes Rho-kinase activity, MLC phosphorylation and actomyosin contractility, which, in turn, enhances VE-cadherin accumulation at cell junctions and thereby vessel stability 33,34 .…”

Dynamics between actin and the VE-cadherin/catenin complex

“…[65][66][67] Many of these functions were also demonstrated for regulation of the VE-cadherin in endothelium. [68][69][70][71][72][73][74][75][76] Importantly, recent data indicates the involvement of p120 ctn in controlling ARP2/3 complex-mediated actin polymerization at endothelial junctions, by binding to the nuclear-promoting factors Wiskott-Aldrich Syndrome Protein (N-WASP) 21 and to cortactin. 77,78 Both the ARP2/3 complex 11,21 and cortactin [79][80][81][82][83][84][85] control endothelial integrity, and particularly, N-WASP control ARP2/3 complex-mediated formation of new VE-cadherin adhesion sites, which drive the VE-cadherin dynamics.…”

Human astrocytes/astrocyte-conditioned medium and shear stress enhance the barrier properties of human brain microvascular endothelial cells

“…Previous studies suggest that permeability of endothelial and epithelial cell is regulated by components of tight and adherens junction proteins, which include occludin [32] VE-cadherin [2,17,38], claudin [26], ZO-1 [29,62,71] ZO-2 [31], cingulin [16], 7H6 antigen [65,82] and symplekin [40]. We examined whether the permeability changes occurred in response to astrocyte/ACM and shear stress are correlated with the changes in expression of tight and adherens junction proteins (e.g., ZO-1 and β-catenin, respectively).…”