Neural Wiskott-Aldrich Syndrome Protein (N-WASP)-mediated p120-Catenin Interaction with Arp2-Actin Complex Stabilizes Endothelial Adherens Junctions

Abstract

Background: Mechanisms linking cortical actin with adherens junctions (AJs) required for forming restrictive endothelial barrier remain unclear. Results: We show that neural Wiskott-Aldrich syndrome protein (N-WASP) binds AJ constituent, p120-catenin, forms cortical actin, and links AJs with actin. Conclusion: N-WASP stabilizes AJs and thereby maintains endothelial barrier function. Significance: N-WASP represents a novel target for preventing leaky endothelial barrier syndrome.

Role of N-WASP in Endothelial Monolayer Formation and Integrity

“…Our observation of increased TER following N-WASP depletion conflicts with a previous study, which found the opposite effect: decreased TER following N-WASP depletion in endothelial cells (16). Our studies reveal that the previous result was due to an off target effect of one siRNA in the pool that was used.…”

“…We observed an increase in the number and staining intensity of longitudinal actin fibers (Fig. 6, upper panels), similar to the previous report (16). In contrast, when we used the pool of three siRNAs (11, 12, and 13, excluding 14), we did not observe this change in actin longitudinal fibers (Fig.…”

“…A previous report reached the opposite conclusion, that depletion of N-WASP leads to loss of endothelial monolayer integrity as measured by transendothelial electrical resistance, consistent with the finding of gaps between endothelial cells in the monolayer (16). We initially replicated these results and observed similar phenotypes using a pool of four siRNA oligonucleotides.…”

“…Recruitment and activation of N-WASP may be downstream of FAK (32), which is recruited to S1P-induced lamellipodia (33). In addition, N-WASP is known to interact with p120-catenin at endothelial adherens junctions (16), providing a molecular link between adherens junctions and actin assembly. In turn, p120-catenin controls VE-cadherin levels at endothelial cell junctions by effects on endocytosis (34 -36).…”

“…N-WASP, one of these proteins, is localized to cell membranes and functions there to promote actin assembly and actin-based cellular functions, such as endocytosis (14,15). The adherens junction component, p120-catenin, interacts with N-WASP to provide a link between the actin cytoskeleton and cell-cell contacts (16).…”