Angiotensin II type 2 receptor-dependent increases in nitric oxide synthase expression in the pulmonary endothelium is mediated via a G alpha(i3)/Ras/Raf/MAPK pathway

作者：Li Jianyu; Zhao Xiangmin; Li Xinmei; Lerea Kenneth M; Olson Susan C^*

来源：American Journal of Physiology - Cell Physiology, 2007, 292(6): C2185-C2196.

DOI：10.1152/ajpcell.00204.2006

• Src
• mitogen-activated protein kinase

We have previously reported that angiotensin II (ANG II) stimulated Src tyrosine kinase via a pertussis toxin-sensitive type 2 receptor, which, in turn, activates MAPK, resulting in an increase in nitric oxide synthase ( NOS) expression in pulmonary artery endothelial cells (PAECs). The present study was designed to investigate the pathway by which ANG II activates Src leading to an increase in ERK1/ERK2 phosphorylation and an increase in NOS protein in PAECs. Transfection of PAECs with G alpha(i3) dominant negative (DN) cDNA blocked the ANG II-dependent activation of Src, ERK1/ERK2 phosphorylation, and increase in NOS expression. ANG II stimulated an increase in tyrosine phosphorylation of sequence homology of collagen (Shc; 15 min) that was prevented when PAECs were pretreated with 4-amino5-(4-chlorophenyl)-7-(t-butyl)pyrazolo-[3,4-D] pyrimidine (PP2), a Src inhibitor. ANG II induced a Src-dependent association between Shc and growth factor receptor-bound protein 2 (Grb2) and between Grb2 and son of sevenless (Sos), both of which were maximal at 15 min. The ANG II-dependent increase in Ras GTP binding was prevented when PAECs were pretreated with the AT2 antagonist PD-123319 or with PP2 or were transfected with Src DN cDNA. ANG II-dependent activation of MAPK and the increase in endothelial NOS ( eNOS) were prevented when PAECs were transfected with Ras DN cDNA or treated with FTI-277, a farnesyl transferase inhibitor. ANG II induction of Raf-1 phosphorylation was prevented when PAECs were pretreated with PD-123319 and PP2. Raf kinase inhibitor 1 prevented the ANG II-dependent increase in eNOS expression. Collectively, these data suggest that G alpha(i3), Shc, Grb2, Ras, and Raf-1 link Src to activation of MAPK and to the AT(2)-dependent increase in eNOS expression in PAECs.

• 出版日期2007-6