RESUMEN
The protective effect of intermittent hypoxia (IH) preconditioning against oxidative injury in hepatic cells was investigated and the involvement of the PINK1/Parkin-mediated mitophagy regulated by nuclear respiratory factor 1 (NRF-1) was evaluated. The results showed that IH preconditioning protected HepG2 cells against oxygen and glucose deprivation/reperfusion (OGD/Rep)-induced injury and protected WRL68 cells against H2O2 or AMA-induced oxidative injury. IH preconditioning up-regulated the protein level of NRF-1, PINK1, Parkin, and LC3 II, promoted the recruitment of the cytosolic Parkin, indicating the initiation of the PINK1/Parkin-mediated mitophagy in WRL68 cells. When NRF-1 was down-regulated by NRF-1 specific shRNA, the protein level of PINK1 and Parkin as well as the mitophagy level were significantly decreased. After IH preconditioning, the protein level of PINK1 and the recruitment of Parkin in CCCP-treated group were significantly higher than that of the control group, indicating the increased mitophagy capacity. And the increased mitophagy capacity induced by IH preconditioning was also reduced by down-regulation of NRF-1. Furthermore, the protective effect of IH preconditioning against H2O2-induced oxidative injury in WRL68 cells was inhibited when NRF-1 or PINK1 was down-regulated by specific shRNA. Mitochondrial ROS generation may be responsible for the increased expression of NRF-1 induced by IH preconditioning. In conclusion, the PINK1/Parkin-mediated mitophagy regulated by NRF-1 was involved in IH preconditioning-induced protective effect against oxidative cellular injury in hepatic cells.
Asunto(s)
Hepatocitos/citología , Precondicionamiento Isquémico/métodos , Factor Nuclear 1 de Respiración/metabolismo , Proteínas Quinasas/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Línea Celular , Citosol/metabolismo , Células Hep G2 , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Humanos , Peróxido de Hidrógeno/efectos adversos , Potencial de la Membrana Mitocondrial , Mitocondrias/metabolismo , Mitofagia , Modelos Biológicos , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo , Regulación hacia ArribaRESUMEN
Previous studies have demonstrated that two Parkinson'sdisease-associatedgenes PINK1 and Parkin play a key role in mitochondrial quality control. But until now, the transcriptional regulation of these two genes under normal physiological conditions are not well understood. In this study, the transcriptional regulation of PINK1 and Parkin genes by nuclear respiratory factor 1 (NRF-1) and its effect on PINK1/Parkin-mediated mitophagy were studied. The NRF-1 binding sites in the promoter regions of human PINK1 and Parkin genes were analyzed by JASPER software and were confirmed by chromatin immunoprecipitation (ChIP) assay. The transcriptional activities and the expressions of PINK1 and Parkin genes were positively regulated by NRF-1 in HEK293T cells and in SH-SY5Y cells. Furthermore, NRF-1 over-expression (OE) up-regulated the protein level of full-length PINK1 in CCCP-treated cells, indicating the enhanced PINK1/Parkin-mediated mitophagy. When NRF-1 expression was transient orstableknockdown, the CCCP-induced mitophagy was alleviated as characterized by the reduced protein level of full-length PINK1, the declined ratio of LC3 II to LC3 I, and the decreasedratioof Mt-keimafluorescenceintensityexcited at 552 nm to that excited at 488 nm. In conclusion, NRF-1 has a positive regulatory effect on the transcription of PINK1 and Parkin genes, and involves in mitochondrial quality control through regulating PINK1/Parkin-mediated mitophagy.
Asunto(s)
Regulación de la Expresión Génica/genética , Mitocondrias/metabolismo , Factor Nuclear 1 de Respiración/metabolismo , Proteínas Quinasas/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Sitios de Unión/genética , Carbonil Cianuro m-Clorofenil Hidrazona/farmacología , Línea Celular Tumoral , Biología Computacional/métodos , Células HEK293 , Humanos , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Mitofagia/efectos de los fármacos , Mitofagia/genética , Factor Nuclear 1 de Respiración/genética , Regiones Promotoras Genéticas/genética , Proteínas Quinasas/genética , Interferencia de ARN , ARN Interferente Pequeño/genética , Especies Reactivas de Oxígeno/metabolismo , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
It has been proved that asiatic acid (AA) directly targets mitochondria and acts as a mild mitochondrial uncoupler. In this study, we aim to investigate the protective effects of AA against ischemia/reperfusion (I/R)-induced liver injury in rats and some underlying mechanisms involved were elucidated. The results showed that 50mg/kg AA pre-treatment significantly reduced I/R-induced liver damage, characterized by the decreased release of aspartate aminotransferase (AST) and TNF-α. Furthermore, AA pre-treatment dramatically inhibited the production of MDA and increased the hepatic SOD, catalase activities and GSH levels in liver tissue of I/R rats which indicated that AA ameliorated I/R-induced liver damage by reducing oxidative stress. In isolated liver mitochondria in I/R rats, AA improved mitochondrial respiration, decreased mitochondrial MDA level, prevented I/R-induced drop of mitochondrial membrane potential (MMP) and increased ATP content, indicating the protective effect of AA against I/R-induced mitochondrial oxidative damage. In isolated liver mitochondria from normal rats, AA was found to effectively block succinate-driven H2O2 production no matter of the presence or absence of rotenone. In addition, AA showed a clear protective effect against anoxia/reoxygenation (A/R)-induced injury in isolated rat liver mitochondria when malate/glutamate were used as respiratory substrates. After AA treatment, mitochondrial respiratory dysfunction induced by A/R was ameliorated. Also, A/R-induced mitochondrial ROS generation was significantly inhibited by AA. In conclusion, AA can attenuate I/R-induced liver damage in rats and A/R-induced mitochondrial injury in isolated rat liver mitochondria by inhibiting oxidative stress and restoring mitochondrial function. Therefore, AA might have potential as a mitochondrial protective agent for use in clinical treatment of hepatic I/R injury.