Angiotensin-(1-7) Through Receptor Mas Mediates Endothelial Nitric Oxide Synthase Activation via Akt-Dependent Pathways

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 49; no. 1; pp. 185 - 192
• Main Authors: Sampaio, Walkyria Oliveira, dos Santos, Robson Augusto Souza, Faria-Silva, Raphael, da Mata Machado, Leonor Tapias, Schiffrin, Ernesto L, Touyz, Rhian M
• Format: Journal Article
• Language: English
• Published: United States American Heart Association, Inc 01.01.2007
• Subjects: Angiotensin I - pharmacology; Angiotensin I - physiology; Animals; Aorta - cytology; Cells, Cultured; CHO Cells - metabolism; Cricetinae; Cricetulus; Endothelial Cells - metabolism; Enzyme Activation - physiology; Humans; Nitric Oxide - metabolism; Nitric Oxide Synthase Type III - metabolism; Peptide Fragments - pharmacology; Peptide Fragments - physiology; Phosphorylation; Protein Processing, Post-Translational - physiology; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - physiology; Proto-Oncogene Proteins c-akt - physiology; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - physiology; Transfection
• ISSN: 0194-911X; 1524-4563
• DOI: 10.1161/01.HYP.0000251865.35728.2f

Angiotensin-(1-7) [Ang-(1-7)] causes endothelial-dependent vasodilation mediated, in part, by NO release. However, the molecular mechanisms involved in endothelial NO synthase (eNOS) activation by Ang-(1-7) remain unknown. Using Chinese hamster ovary cells stably transfected with Mas cDNA (Chinese hamster ovary-Mas), we evaluated the underlying mechanisms related to receptor Mas–mediated posttranslational eNOS activation and NO release. We further examined the Ang-(1-7) profile of eNOS activation in human aortic endothelial cells, which constitutively express the Mas receptor. Chinese hamster ovary-Mas cells and human aortic endothelial cell were stimulated with Ang-(1-7; 10 mol/L; 1 to 30 minutes) in the absence or presence of A-779 (10 mol/L). Additional experiments were performed in the presence of the phosphatidylinositol 3-kinase inhibitor wortmannin (10 mol/L). Changes in eNOS (at Ser1177/Thr495 residues) and Akt phosphorylation were evaluated by Western blotting. NO release was measured using both the fluorochrome 2,3-diaminonaphthalene and an NO analyzer. Ang-(1-7) significantly stimulated eNOS activation (reciprocal phosphorylation/dephosphorylation at Ser1177/Thr495) and induced a sustained Akt phosphorylation (P<0.05). Concomitantly, a significant increase in NO release was observed (2-fold increase in relation to control). These effects were blocked by A-779. Wortmannin suppressed eNOS activation in both Chinese hamster ovary-Mas and human aortic endothelial cells. Our findings demonstrate that Ang-(1-7), through Mas, stimulates eNOS activation and NO production via Akt-dependent pathways. These novel data highlight the importance of the Ang-(1-7)/Mas axis as a putative regulator of endothelial function.