Activation of Vascular Endothelial Growth Factor (VEGF) Receptor 2 Mediates Endothelial Permeability Caused by Cyclic Stretch

Abstract

High tidal volume mechanical ventilation and the resultant excessive mechanical forces experienced by lung vascular endothelium are known to lead to increased vascular endothelial leak, but the underlying molecular mechanisms remain incompletely understood. One reported mechanotransduction pathway of increased endothelial cell (EC) permeability caused by high magnitude cyclic stretch (18% CS) involves CS-induced activation of the focal adhesion associated signalosome, which triggers Rho GTPase signaling. This study identified an alternative pathway of CS-induced EC permeability. We show here that high magnitude cyclic stretch (18% CS) rapidly activates VEGF receptor 2 (VEGFR2) signaling by dissociating VEGFR2 from VE-cadherin at the cell junctions. This results in VEGFR2 activation, Src-dependent VE-cadherin tyrosine phosphorylation, and internalization leading to increased endothelial permeability. This process is also accompanied by CS-induced phosphorylation and internalization of PECAM1. Importantly, CSinduced endothelial barrier disruption was attenuated by VEGFR2 inhibition. 18% CS-induced EC permeability was linked to dissociation of cell junction scaffold afadin from the adherens junctions. Forced expression of recombinant afadin in pulmonary endothelium attenuated CS-induced VEGFR2 and VE-cadherin phosphorylation, preserved adherens junction integrity and VEGFR2⅐VE-cadherin complex, and suppressed CS-induced EC permeability. This study shows for the first time a mechanism whereby VEGFR2 activation mediates EC permeability induced by pathologically relevant cyclic stretch. In this mechanism, CS induces dissociation of the VEcadherin⅐VEGFR2 complex localized at the adherens juctions, causing activation of VEGFR2, VEGFR2-mediated Src-dependent phosphorylation of VE-cadherin, disassembly of adherens junctions, and EC barrier failure.

Substrate stiffness and VE-cadherin mechano-transduction coordinate to regulate endothelial monolayer integrity

“…For example, pathological levels of mechanical stretch, as in ventilator induced lung injury [7,57], activate kinase cascades via VE-cadherin and VEGFR2 to induce endothelial junction remodeling [20]. Similar processes might also predict that arterioles in fibrotic lung tissue would be more susceptible to damage by mechanical ventilation.…”

“…Fluid shear alignment (flow sensing), for example, involves force transduction complexes at interendothelial junctions that require platelet endothelial cell adhesion molecule one (PECAM-1), vascular endothelial growth factor 2 (VEGFR2), and vascular endothelial cadherin (VE-cadherin) [1,18,19], which is the main adhesion molecule at endothelial junctions. Besides fluid shear stress, other perturbations such as cyclic stretch in the lung appear to activate a similar signaling cascade [20]. In biophysical studies, we showed that directly perturbing VE-cadherin receptors on cell surfaces with VE-cadherin-modified magnetic beads activated similar signals as in flow sensing, but without PECAM-1 [21].…”

The Andes Virus Nucleocapsid Protein Directs Basal Endothelial Cell Permeability by Activating RhoA

“…In fact even inapparent cellular stresses like breathing-directed cyclic stretching of the pulmonary endothelium (88, 89) may contribute to capillary leakage when uncoupled from normal MEC integrity. The cause of vascular leakage during hantavirus diseases has been speculated to stem from a wide range of effectors, including growth factors, kinins, immune responses, cytokines, T cells, and permeability factors (18–20, 29, 31, 32, 35, 36, 39, 77, 90).…”

Rho GTPases and actomyosin: Partners in regulating epithelial cell-cell junction structure and function

“…Afadin is necessary for maintaining tissue integrity and barrier function under high tension and is particularly important for maintaining adhesion at tricellular junctions (Choi et al, 2016; Tian et al, 2016). The Drosophila Afadin ortholog, Canoe, is critical for linking the actin cytoskeleton to the AJ during the mechanical stresses of development (Choi et al, 2011; Sawyer et al, 2011).…”