eNOS-induced vascular barrier disruption in retinopathy by c-Src activation and tyrosine phosphorylation of VE-cadherin

Hypoxia and the production of vascular endothelial growth factor A (VEGFA) promote blood vessel leakiness and edema in ocular diseases. Therapeutics targeting VEGFA suppress leakiness and edema but aggravate hypoxia; therefore, new therapeutics are needed. We examined the role of endothelial nitric oxide synthase (eNOS) in pathological neovascularization and vessel permeability during oxygen-induced retinopathy. NO formation was suppressed chemically using L-NMMA, or genetically, in eNOS serine to alanine (S1176A) mutant mice, resulting in reduced retinal neoangiogenesis. Both strategies resulted in reduced vascular leakage by stabilizing endothelial adherens junctions through suppressed phosphorylation of vascular endothelial (VE)-cadherin Y685 in a c-Src-dependent manner. Intervention treatment by a single dose of L-NMMA in established retinopathy restored the vascular barrier and prevented leakage. We conclude that eNOS induces destabilization of adherens junctions and vascular hyperpermeability by converging with the VEGFA/VEGFR2/c-Src/VE-cadherin pathway and that this pathway can be selectively inhibited by blocking NO formation.