Insulin-stimulated phosphorylation of endothelial nitric oxide synthase at Ser615 contributes to nitric oxide synthesis
Résumé
Insulin stimulates endothelial nitric oxide synthesis via protein kinase B/Akt-mediated phosphorylation and activation of endothelial nitric oxide synthase at Ser1177. In previous studies, we have demonstrated that stimulation of endothelial nitric oxide synthase phosphorylation at Ser1177 may be required, yet is not sufficient for insulin-stimulated nitric oxide synthesis. We therefore investigated the role of phosphorylation of endothelial nitric oxide synthase at alternative sites to Ser1177 as candidate parallel mechanisms contributing to insulin-stimulated nitric oxide synthesis. Stimulation of human aortic endothelial cells with insulin rapidly stimulated phosphorylation of both Ser615 and Ser1177 on endothelial NO synthase, whereas phosphorylation of Ser114, Thr495 and Ser633 was unaffected. Insulin-stimulated Ser615 phosphorylation was abrogated by incubation with the phosphatidylinositol-3'-kinase inhibitor, wortmannin, infection with adenoviruses expressing a dominant negative mutant protein kinase B/Akt or preincubation with tumour necrosis factor-alpha but was unaffected by high culture glucose concentrations. Mutation of Ser615 to Ala615 reduced insulin-stimulated nitric oxide synthesis, whereas mutation of Ser615 to Asp615 increased nitric oxide production by nitric oxide synthase in which Ser1177 had been mutated to an Asp1177. We propose that the rapid, protein kinase B-mediated stimulation of phosphorylation of Ser615 contributes to insulin-stimulated nitric oxide synthesis.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...