RESUMO
This study is to investigate the underlying mechanisms of mitochondrial quality control (MQC) regulated by HtrA2/Omi during ischemia/reperfusion (I/R). We utilized the mnd2 mouse model, which has a missense mutation in HtrA2/Omi, to investigate the HtrA2/Omi regulation in mitochondria after I/R injury in the cerebral cortex. Compared to homozygous (HtrA2mnd2) mice, heterozygous (HtrA2Hetero) mice showed aging signs at a later age, increased HtrA2/Omi expression in the brain cortex, and lesser neurodegenerative signs. The brain cortex of HtrA2Hetero mice had increased superoxide dismutase (SOD) activity; lower levels of malondialdehyde (MDA); higher expressions of mitochondrial unfolded protein response (mtUPR)-related proteins, NADH dehydrogenase [ubiquinone] iron-sulfur protein 7 (Ndufs7), and uncoupling protein 2 (UCP2) proteins; more mitochondrial fission; higher levels of ATP and mtDNA copies; elevated sirtuin 3 (SIRT3) activity; and increased NAD+/NADH ratio. After 1.5 h of I/R, the brain cortex of HtrA2Hetero mice had a larger infarction size, reduced HtrA2/Omi expression, decreased S-X-linked inhibitor of apoptosis protein (XIAP), and increased C-Caspase3 than that of wild-type animals (WT). Mitochondria from the HtrA2Hetero brain cortex showed decreased ATP production and MQC deficiency after 1.5 h I/R. Genipin pre-treatment reduced the aforementioned I/R injury in the HtrA2Hetero brain cortex. In conclusion, mitochondrial function is compensated in the HtrA2Hetero brain cortex via the upregulation of the UCP2-SIRT3-PGC1 axis. Decreased HtrA2/Omi function damages mitochondrial quality in the HtrA2Hetero mouse brain cortex, leading to more brain I/R injury. Genipin pre-treatment ameliorates brain damages via the mitochondrial UCP2-SIRT3-PGC1 axis.
Assuntos
Reprogramação Celular/genética , Córtex Cerebral/metabolismo , Serina Peptidase 2 de Requerimento de Alta Temperatura A/fisiologia , Hipóxia Encefálica/genética , Hipóxia Encefálica/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/metabolismo , Sirtuína 3/metabolismo , Proteína Desacopladora 2/metabolismo , Animais , Modelos Animais de Doenças , Camundongos TransgênicosRESUMO
Cerebral ischemia-reperfusion injury is a thorny issue in the treatment of stroke. Energy depletion and oxidative stress are the core mechanisms underlying cerebral ischemia-reperfusion injury. Mitochondrial function is involved in energy production and oxidative stress. It has been reported that mitochondrial uncoupling protein 2 (UCP2) may be involved in the regulation of cerebral ischemia-reperfusion injury. We hypothesized that UCP2 can regulate cerebral ischemia-reperfusion injury by regulating energy supply and oxidative stress. To test this hypothesis, we used a middle cerebral artery occlusion model in male C57BL/6 mice with/without genipin--an UCP2-specific inhibitor. We measured the expression and/or activity of UCP2, SIRT3, the level of ATP, and antioxidant-related molecules in the cerebral cortex and the LDH in serum after ischemia-reperfusion, the level of apoptosis was reflected by the level of cleaved-caspase3 and tunel staining. The results showed an increase in the expression of UCP2, coinciding with an increase in the level of apoptosis, NAD+/NADH ratio, SIRT3 activity, LDH release and a decrease in the level of ATP and antioxidant-related molecules after 1â¯h of ischemia and 24â¯h of reperfusion. These findings suggest that UCP2 may regulate energy supply and oxidative stress in ischemia-reperfusion injury. Interestinly, above changes can be reserved by administration of genipin with the brain damage level going down. In conclusion, the UCP2-SIRT3 signaling pathway is involved in the regulation of cerebral ischemia-reperfusion injury as a bridge between energy metabolism and oxidative stress. Genipin protects against cerebral ischemia-reperfusion injury by inhibiting UCP2.
Assuntos
Iridoides/uso terapêutico , Mitocôndrias/metabolismo , Fármacos Neuroprotetores/uso terapêutico , Traumatismo por Reperfusão/prevenção & controle , Sirtuína 3/metabolismo , Acidente Vascular Cerebral/tratamento farmacológico , Proteína Desacopladora 2/metabolismo , Animais , Apoptose , Metabolismo Energético , Iridoides/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo , Espécies Reativas de Oxigênio , Transdução de SinaisRESUMO
Bcl-2, which belongs to the Bcl-2 family, is frequently overexpressed in various types of cancer cells and contributes to drug resistance. However, the function of Bcl-2 in cisplatin resistance in human ovarian cancer cells is not fully understood. In this study, we found that the pharmacological inhibitor ABT737 or genetic knockdown of Bcl-2 increased cisplatin cytotoxicity in cisplatin-resistant ovarian cancer cells. Additionally, treatment with ABT737 or Bcl-2 siRNA increased cisplatin-induced free Ca2+ levels in the cytosol and mitochondria, which increased endoplasmic reticulum (ER)-associated and mitochondria-mediated apoptosis. In addition, ABT737 or Bcl-2 siRNA increased the ER-mitochondria contact sites induced by cisplatin in cisplatin-resistant SKOV3/DDP ovarian cancer cells. Consistently with the in vitro results, ABT737 potently synergized with cisplatin in inhibiting the growth of human ovarian cancer xenografts in nude mice. Collectively, these results indicate that pharmacological inhibitors or genetic knockdown of Bcl-2 may be a potential strategy for improving cisplatin treatment of ovarian cancer.
