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Receptors and Signal Transduction

Angiotensin II induces RhoA activation through SHP2-dependent dephosphorylation of the RhoGAP p190A in vascular smooth muscle cells

¹Institut National de la Santé et de la Recherche Médicale, UMR915, l'institut du thorax, Nantes; ²Université de Nantes, Nantes; ³Centre Hospitalier Universitaire Nantes, Nantes, F-44000 France

Submitted 23 April 2009 ; accepted in final form 13 August 2009

Angiotensin II (ANG II) is a major regulator of blood pressure that essentially acts through activation of ANG II type 1 receptor (AT1R) of vascular smooth muscle cells (VSMC). AT1R activates numerous intracellular signaling pathways, including the small G protein RhoA known to control several VSMC functions. Nevertheless, the mechanisms leading to RhoA activation by AT1R are unknown. RhoA activation can result from activation of RhoA exchange factor and/or inhibition of Rho GTPase-activating protein (GAP). Here we hypothesize that a RhoGAP could participate to RhoA activation induced by ANG II in rat aortic VSMC. The knockdown of the RhoGAP p190A by small interfering RNA (siRNA) abolishes the activation of RhoA-Rho kinase pathway induced after 5 min of ANG II (0.1 µM) stimulation in rat aortic VSMC. We then show that AT1R activation induces p190A dephosphorylation and inactivation. In addition, expression of catalytically inactive or phosphoresistant p190A mutants increases the basal activity of RhoA-Rho kinase pathway, whereas phosphomimetic mutant inhibits early RhoA activation by ANG II. Using siRNA and mutant overexpression, we then demonstrate that the tyrosine phosphatase SHP2 is necessary for 1) maintaining p190A basally phosphorylated and activated by the tyrosine kinase c-Abl, and 2) inducing p190A dephosphorylation and RhoA activation in response to AT1R activation. Our work then defines p190A as a new mediator of RhoA activation by ANG II in VSMC.

p190A; phosphorylation; SH2-containing protein tyrosine phosphatase 2; Abelson tyrosine kinase

This article has been cited by other articles:

				K. Kimura and S. Eguchi 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" Am J Physiol Cell Physiol, November 1, 2009; 297(5): C1059 - C1061. [Full Text] [PDF]