The Ca2+-calmodulin-Ca2+/calmodulin- dependent protein kinase II signaling pathway is involved in oxidative stress-induced mitochondrial permeability transition and apoptosis in isolated rat hepatocytes
Oxidative stress (OS) is a common event in most hepatopathies, leading to mitochondrial permeability transition pore (MPTP) formation and further exacerbation of both OS from mitochondrial origin and cell death. Intracellular Ca2+ increase plays a permissive role in these events, but the underlying...
| Autores: | , , , , , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2014 |
| País: | Argentina |
| Recursos: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositório: | CONICET Digital (CONICET) |
| Idioma: | inglês |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/6104 |
| Acesso em linha: | http://hdl.handle.net/11336/6104 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Oxidative Stress Tert-Butyl Hydroperoxide Ca2+/Calmodulin-Dependent Protein Kinase Ii Mitochondrial Permeability Transition Pore Apoptosis Cytochrome C https://purl.org/becyt/ford/3.1 https://purl.org/becyt/ford/3 |
| Resumo: | Oxidative stress (OS) is a common event in most hepatopathies, leading to mitochondrial permeability transition pore (MPTP) formation and further exacerbation of both OS from mitochondrial origin and cell death. Intracellular Ca2+ increase plays a permissive role in these events, but the underlying mechanisms are poorly known. We examined in primary cultured rat hepatocytes whether the Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) signaling pathway is involved in this process, by using tert-butyl hydroperoxide (tBOOH) as a pro-oxidant, model compound. tBOOH (500 μM, 15 min) induced MPTP formation, as assessed by measuring mitochondrial membrane depolarization as a surrogate marker, and increased lipid peroxidation in a cyclosporin A (CsA)-sensitive manner, revealing the involvement of MPTPs in tBOOH-induced radical oxygen species (ROS) formation. Intracellular Ca2+ sequestration with BAPTA/AM, CaM blockage with W7 or trifluoperazine, and CaMKII inhibition with KN-62 all fully prevented tBOOH-induced MPTP opening and reduced tBOOH-induced lipid peroxidation to a similar extent to CsA, suggesting that Ca2+/CaM/CaMKII signaling pathway fully mediates MPTP-mediated mitochondrial ROS generation. tBOOH-induced apoptosis, as shown by flow cytometry of annexin V/propidium iodide, mitochondrial release of cytochrome c, activation of caspase-3 and increase in the Bax-to-Bcl-xL ratio, and the Ca2+/CaM/CaMKII signaling antagonists fully prevented these effects. Intramitochondrial CaM and CaMKII were partially involved in tBOOH-induced MPTP formation, since W7 and KN-62 both attenuated the tBOOH-induced, MPTP-mediated swelling of isolated mitochondria. We concluded that Ca2+/CaM/CaMKII signaling pathway is a key mediator of OS-induced MPTP formation and the subsequent exacerbation of OS from mitochondrial origin and apoptotic cell death. |
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