Angiotensin II-induced oxidative stress resets the Ca2+ dependence of Ca2+-calmodulin protein kinase II and promotes a death pathway conserved across different species.
BACKGROUND
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.


RESULTS
Ang II (1 micromol/L) reduced cat/rat myocytes viability by approximately 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.
Palomeque
Julieta
J
Centro de Investigaciones Cardiovasculares, Facultad de Medicina, Universidad Nacional de La Plata, Centro Científico Tecnológico CONICET, La Plata, Argentina.
Rueda
Omar Velez
OV
Sapia
Luciana
L
Valverde
Carlos A
CA
Salas
Margarita
M
Petroff
Martin Vila
MV
Mattiazzi
Alicia
A
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001596:Benzylamines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism; D002415:Cats; D002470:Cell Survival; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010455:Peptides / Q000235:genetics / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013045:Species Specificity; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D008625:Tiopronin / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000096926:Benzenesulfonamides
D000804:Angiotensin II; D001596:Benzylamines; D002118:Calcium; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002147:Calmodulin; D002614:Chelating Agents; D004533:Egtazic Acid; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D007093:Imidazoles; D019255:NADPH Oxidases; D009861:Onium Compounds; D010455:Peptides; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D017382:Reactive Oxygen Species; D013449:Sulfonamides; D008625:Tiopronin; D048051:p38 Mitogen-Activated Protein Kinases; C527819:AC3-I peptide; C514527:autocamptide-2-related inhibitory peptide II; C072105:KN 93; D000096926:Benzenesulfonamides; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C017967:W 7; C007517:diphenyleneiodonium; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole