CHARACTERIZATION OF ANG II AT2 SIGNALING PATHWAY IN PND15 RAT HINDBRAIN

SEGUIN LR, CIUFFO GM

San Miguel de Tucumán, Tucumán. ARGENTINA

Congreso; Reunion Anual de SAIB; 2009

The classical effects of Ang II are well known but new evidences involve this peptide in development. The aim of the present study was to elucidate the non-classical signaling pathway of Ang II AT2 receptors in PND15 rat hindbrain, a critical developmental stage. Membrane preparations were stimulated with Ang II (10-7M) in the presence or not of competitors and the c-Src inhibitor PP2 or its inactive analog PP3, solubilized and immunoprecipitated with anti-AT2 or anti-SHP-1. Following Ang II stimulation, SHP-1 associates to AT2 receptors but not to AT1 subtype. Immunocomplexes obtained with anti-AT2 or anti-SHP-1 exhibited PTPase activity, blocked by PD123319 (AT2 antagonist) or PP2. SHP-1 activation was correlated with tyr-phosphorylation level of SHP-1 in immunocomplexes. Both immunocomplexes contained c-Src and PP2 blocked SHP-1 tyr-phosphorylation as well as activation and association SHP-1 to c-Src. Immunocomplexes also contained a high molecular weight protein (125-130 kDa). To further investigate this protein we assayed the participation of FAK and paxillin, which were not present in immunocomplexes. Thus Ang II stimulation via AT2 subtype, induced tyr-phosphorylation of SHP-1 and formation of immunocomplexes AT2-SHP-1-Src. These results demonstrate SHP-1 activation by Ang II AT2 receptors and thus a potential physiological role of these receptors in developing hindbrain.