Angiotensin II–Induced Oxidative Stress Resets the Ca 2+ Dependence of Ca 2+ –Calmodulin Protein Kinase II and Promotes a Death Pathway Conserved Across Different Species

• Published in: Circulation research 2009-12, Vol.105 (12), p.1204-1212
• Main Authors: Palomeque, Julieta, Rueda, Omar Velez, Sapia, Luciana, Valverde, Carlos A., Salas, Margarita, Petroff, Martin Vila, Mattiazzi, Alicia
• Format: Article
• Language: English
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/CIRCRESAHA.109.204172

Rationale: Angiotensin (Ang) II–induced apoptosis was reported to be mediated by different signaling molecules. Whether these molecules are either interconnected in a single pathway or constitute different and alternative cascades by which Ang II exerts its apoptotic action, is not known. Objective: To investigate in cultured myocytes from adult cat and rat, 2 species in which Ang II has opposite inotropic effects, the signaling cascade involved in Ang II–induced apoptosis. Methods and Results: Ang II (1 μmol/L) reduced cat/rat myocytes viability by ≈40%, in part, because of apoptosis (TUNEL/caspase-3 activity). In both species, apoptosis was associated with reactive oxygen species (ROS) production, Ca 2+ /calmodulin–dependent protein kinase (CaMK)II, and p38 mitogen-activated protein kinase (p38MAPK) activation and was prevented by the ROS scavenger MPG (2-mercaptopropionylglycine) or the NADPH oxidase inhibitor DPI (diphenyleneiodonium) by CaMKII inhibitors (KN-93 and AIP [autocamtide 2-related inhibitory peptide]) or in transgenic mice expressing a CaMKII inhibitory peptide and by the p38MAPK inhibitor, SB202190. Furthermore, p38MAPK overexpression exacerbated Ang II–induced cell mortality. Moreover, although KN-93 did not affect Ang II–induced ROS production, it prevented p38MAPK activation. Results further show that CaMKII can be activated by Ang II or H 2 O 2 , even in the presence of the Ca 2+ chelator BAPTA-AM, in myocytes and in EGTA-Ca 2+ –free solutions in the presence of the calmodulin inhibitor W-7 in in vitro experiments. Conclusions: (1) The Ang II–induced apoptotic cascade converges in both species, in a common pathway mediated by ROS-dependent CaMKII activation which results in p38MAPK activation and apoptosis. (2) In the presence of Ang II or ROS, CaMKII may be activated at subdiastolic Ca 2+ concentrations, suggesting a new mechanism by which ROS reset the Ca 2+ dependence of CaMKII to extremely low Ca 2+ levels.