VE-Cadherin Phosphorylation Regulates Endothelial Fluid Shear Stress Responses through the Polarity Protein LGN

Abstract

Summary Fluid shear stress due to blood flow on the vascular endothelium regulates blood vessel development, remodeling, physiology and pathology [1, 2]. A complex consisting of PECAM-1, VE-cadherin and vascular endothelial growth factor receptors (VEGFRs) that resides at endothelial cell-cell junctions transduces signals important for flow-dependent vasodilation, blood vessel remodeling and atherosclerosis. PECAM-1 transduce forces to activate src family kinases (SFKs), which phosphorylate and transactivate VEGFRs [3-5]. By contrast, VE-cadherin functions as an adapter that interacts with VEGFRs through their respective cytoplasmic domains and promotes VEGFR activation in flow [6]. Indeed, shear stress triggers rapid increases in force across PECAM-1 but decreases the force across VE-cadherin, in close association with downstream signaling [5]. Interestingly, VE-cadherin cytoplasmic tyrosine Y658 can be phosphorylated by SFKs [7], which is maximally induced by low shear stress in vitro and in vivo [8]. These considerations prompted us to address the involvement of VE-cadherin cytoplasmic tyrosines in flow sensing. We found that phosphorylation of a small pool of VE-cadherin on Y658 is essential for flow sensing through the junctional complex. Y658 phosphorylation induces dissociation of p120ctn, which allows binding of the polarity protein LGN. LGN is then required for multiple flow responses in vitro and in vivo, including activation of inflammatory signaling at regions of disturbed flow, and flow-dependent vascular remodeling. Thus, endothelial flow mechanotransduction through the junctional complex is mediated by a specific pool of VE-cadherin that is phosphorylated on Y658 and bound to LGN.

Vascular permeability in retinopathy is regulated by VEGFR2 Y949 signaling to VE-cadherin

“…Phosphorylation of the site acts to displace bound p120 catenin which destabilized adherens junctions [21,22]. VE-cadherin Y658 is phosphorylated by Src family kinases, with low levels of shear stress leading to maximal pY658 immunostaining [19,62]. In the OIR model, tufts are known to have perturbed perfusion, which may drive the high pY658 intensity in tufts, to a similar extent in the WT and mutant models, as observed in this study.…”

The Desmosomal Cadherin Desmoglein-2 Experiences Mechanical Tension as Demonstrated by a FRET-Based Tension Biosensor Expressed in Living Cells

“…In unstretched cells, we observed a significant decrease in the FRET efficiency of the DSG-2 tension sensor as compared to the DSG-2 tailless control ( Figure 4 A,B). Using the previously developed force-FRET relationship for TSmod [ 12 ], the mechanical force across DSG-2 was estimated to be 1.5 pN per molecule (with a standard deviation of 0.84 pN), which is similar to force estimates for E-cadherin [ 4 , 16 ] and VE-cadherin [ 20 ]. Biaxial stretch (9% and 22%) did not significantly alter the FRET for the DSG-2 tension sensor ( Figure 4 C), suggesting that this level of stretch does not affect DSG-2 tension.…”

Mechanotransduction in tumor progression: The dark side of the force

“…The underlying molecular mechanism of the fluid flow–induced activation of angiogenesis involves PECAM-1, which mechanotransductively activates Src family kinases that transactivate VEGF receptors (VEGFRs) and phosphorylate Y658-VE-Cadherins at cell–cell junctions. Both activated VEGFRs and VE-Cadherins trigger multiple downstream pathways regulating endothelial cell alignment along the direction of the flow and flow dependent vascular remodeling, respectively ( Conway et al, 2017 ).…”