• Masayuki Sugimoto, Masanori Nakayama, Takaaki M Goto, Mutsuki Amano, Kimihiro Komori, and Kozo Kaibuchi.
• Department of Vascular Surgery, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa-ku, Nagoya, Aichi 466-8550, Japan.
• Biochem. Biophys. Res. Commun. 2007 Sep 21; 361 (2): 462-7.

AbstractEndothelial nitric oxide synthase (eNOS) produces nitric oxide (NO), which is involved in various physiological functions of the cardiovascular system. eNOS is activated by dephosphorylation at Thr495 and phosphorylation at Ser1177. Inhibition of Rho-kinase, an effector of the small GTPase RhoA, leads to activation of Akt/PKB, which phosphorylates eNOS at Ser1177 and thereby promotes NO production. However, little is known about the effects of Rho-kinase on phosphorylation of Thr495. We here found that the constitutively active form of Rho-kinase phosphorylated eNOS at Thr495 in vitro. Expression of the constitutively active form of RhoA or Rho-kinase increased this phosphorylation in COS-7 cells. Addition of thrombin to cultured human umbilical vein endothelial cells induced phosphorylation of eNOS at Thr495. Treatment with Y27632, a Rho-kinase inhibitor, suppressed thrombin-induced phosphorylation at Thr495. These results indicate that Rho-kinase can directly phosphorylate eNOS at Thr495 to suppress NO production in endothelium.

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