Products resulting from oxidation of cell membrane
phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (
OxPAPC) exhibit potent protective effects against lung endothelial cell (EC) barrier dysfunction caused by pathologically relevant mechanical forces and inflammatory agents. These effects were linked to enhancement of peripheral cytoskeleton and cell adhesion interactions mediated by
small GTPase Rac and inhibition of Rho-mediated barrier-disruptive signaling. However, the mechanism of
OxPAPC-induced, Rac-dependent Rho downregulation critical for vascular barrier protection remains unclear. This study tested the hypothesis that Rho negative regulator p190RhoGAP is essential for
OxPAPC-induced lung barrier protection against
ventilator-induced lung injury (VILI), and investigated potential mechanism of p190RhoGAP targeting to adherens junctions (AJ) via
p120-catenin.
OxPAPC induced peripheral translocation of p190RhoGAP, which was abolished by knockdown of Rac-specific
guanine nucleotide exchange factors Tiam1 and Vav2.
OxPAPC also induced Rac-dependent
tyrosine phosphorylation and association of p190RhoGAP with AJ
protein p120-catenin.
siRNA-induced knockdown of p190RhoGAP attenuated protective effects of
OxPAPC against EC barrier compromise induced by
thrombin and pathologically relevant cyclic stretch (18% CS). In vivo, p190RhoGAP knockdown significantly attenuated protective effects of
OxPAPC against
ventilator-induced lung vascular leak, as detected by increased cell count and
protein content in the bronchoalveolar lavage fluid, and tissue neutrophil accumulation in the lung. These results demonstrate for the first time a key role of p190RhoGAP for the vascular endothelial barrier protection in VILI.