Endothelial Nitric Oxide Synthase Inhibits G _12/13 and Rho-Kinase Activated by the Angiotensin II Type-1 Receptor

Abstract

Background-Although, endothelial nitric oxide (NO) synthase (eNOS) is believed to antagonize vascular remodeling induced by the angiotensin II (AngII) type-1 receptor, the exact signaling mechanism remains unclear. Methods and Results-By expressing eNOS to vascular smooth muscle cells (VSMCs) via adenovirus, we investigated a signal transduction mechanism of the eNOS gene transfer in preventing vascular remodeling induced by AngII. We found marked inhibition of AngII-induced Rho/Rho-kinase activation and subsequent VSMC migration by eNOS gene transfer whereas G q -dependent transactivation of the epidermal growth factor receptor by AngII remains intact. This could be explained by the specific inhibition of G 12/13 activation by eNOS-mediated G 12/13 phosphorylation. Conclusion-The eNOS/NO cascade specifically targets the Rho/Rho-kinase system via inhibition of G 12/13 to prevent vascular migration induced by AngII, representing a novel signal cross-talk in cardiovascular protection by NO.

Characterization of Angiotensin II Molecular Determinants Involved in AT1 Receptor Functional Selectivity

“…G protein-coupled receptor kinases phosphorylate the receptor, leading to barrestin recruitment and functional uncoupling of G protein signaling. The AT 1 receptor also activates the G protein G 12 (Ushio-Fukai et al, 1998;Gohla et al, 2000;Sagara et al, 2007;Suzuki et al, 2009). It is known that G 12, through the regulation of RhoGEF proteins, leads to the activation of RhoA/Rho kinase and cytoskeleton reorganization (Siehler, 2009).…”

Angiotensin II type-1 receptor regulates RhoA and Rho-kinase/ROCK activation via multiple mechanisms. Focus on “Angiotensin II induces RhoA activation through SHP2-dependent dephosphorylation of the RhoGAP p190A in vascular smooth muscle cells”

“…In this regard, many G protein-coupled receptors (GPCRs) are believed to increase RhoA activity via the G 12/13 family of G proteins through activation of their effectors, the RGS domain-containing RhoGEFs (p115 RhoGEF, PDZ-RhoGEF, and LARG are the known members) (20,29). The presence of this "basic" mechanism of RhoA/ROCK regulation by a GPCR has been shown in the AT 1 receptor activation of vascular smooth muscle cells (VSMCs) and cardiac myocytes in culture (14,24) and in vivo for arterial contraction stimulated by angiotensin II (28). However, studies published recently (1,27) also suggest that the regulation of RhoA/ROCK by the AT 1 receptor is not limited to the G 12/13 /RGS domain-containing RhoGEF pathway.…”

“…In addition, recent reports and the current study demonstrate that there are other regulatory mechanisms of the Rho/ROCK pathway that is activated by angiotensin II in VSMCs. The nitric oxide protein kinase G cascade (24) and the angiotensin type-2 (AT 2 ) receptor signal transduction pathway (5) appear to be able to inhibit the RhoA/ROCK pathway at the level of G 12/13 and RhoA, respectively. It is also interesting to note that all of these different types of regulation of RhoA/ROCK seem to be independent of the ERK1/2 cascade, which is activated exclusively through G q , and of transactivation of the epidermal growth factor receptor in VSMCs (3,16,17,24).…”

Determination of the Exact Molecular Requirements for Type 1 Angiotensin Receptor Epidermal Growth Factor Receptor Transactivation and Cardiomyocyte Hypertrophy

“…34 Although G␣ q/11 is the obvious candidate for mediating the G protein-dependent effects described herein, it is important to note that other G-protein subunits can be activated by the AT 1 R in both cardiomyocytes and vascular smooth muscle cells. 35 Functional selectivity also describes the ability of ␤-arrestins to act as ligand-regulated scaffolds. 36 Because ␤-arrestin binding precludes catalytic interaction between GPCRs and G proteins, ␤-arrestin binding could be viewed as switching the receptor between two qualitatively, temporally, and spatially distinct signaling modes, G-protein coupled and G-protein uncoupled.…”