Endothelin-1 induces p66Shc activation through EGF receptor transactivation: Role of β1Pix/Gαi3 interaction

Enclothelin-1 (ET-1) is a vasoconstrictor peptide known to be a potent mitogen for glomerular mesangial cells. We have shown that Er-l stimulates the adaptor protein p66Shc through Rac/Cdc42 guanine nucleotide exchange factor beta(1)Pix. In this study, we demonstrate that Er-1-induced serine phosphorylation of p66Shc is mediated through G alpha(i3), Pertussis toxin treatment of cells induced a significant decrease in the interaction between beta(1)Pix and ETA-K and an increase in the binding of G alpha(i3) and G(beta 1) to beta(1)Pix. Activation of heterotrimeric G proteins by AlF4- resulted in an increase of G alpha(i3) binding to beta(1)Pix, which was significantly disrupted in cells expressing beta(1)Pix dimerization deficient mutant beta(1)Pix Delta (602-611). In cells expressing beta(1)Pix Delta (602-611), ET-1-induced p66Shc activation was also significantly decreased. Specific inhibition of EGF receptor by AG1478 blocked ET-1-induced p66Shc activation and the binding of p66Shc and G alpha(i3) to beta(1)Pix. Inhibition of Erk1/2 blocked p66Shc activation induced by ET-1. Altogether, our results indicate that ET-I activates p66Shc through EGF receptor transactivation, leading to the activation of G alpha(i3), beta(1)Pix and Erk1/2. (C) 2009 Elsevier Inc. All rights reserved.