title: Critical role of mitochondrial glutathione in the survival of hepatocytes during hypoxia.
abstract: Hypoxia is known to stimulate reactive oxygen species (ROS) generation. Because reduced glutathione (GSH) is compartmentalized in cytosol and mitochondria, we examined the specific role of mitochondrial GSH (mGSH) in the survival of hepatocytes during hypoxia (5% O2). 5% O2 stimulated ROS in HepG2 cells and cultured rat hepatocytes. Mitochondrial complex I and II inhibitors prevented this effect, whereas inhibition of nitric oxide synthesis with Nomega-nitro-L-arginine methyl ester hydrochloride or the peroxynitrite scavenger uric acid did not. Depletion of GSH stores in both cytosol and mitochondria enhanced the susceptibility of HepG2 cells or primary rat hepatocytes to 5% O2 exposure. However, this sensitization was abrogated by preventing mitochondrial ROS generation by complex I and II inhibition. Moreover, selective mGSH depletion by (R,S)-3-hydroxy-4-pentenoate that spared cytosol GSH levels sensitized rat hepatocytes to hypoxia because of enhanced ROS generation. GSH restoration by GSH ethyl ester or by blocking mitochondrial electron flow at complex I and II rescued (R,S)-3-hydroxy-4-pentenoate-treated hepatocytes to hypoxia-induced cell death. Thus, mGSH controls the survival of hepatocytes during hypoxia through the regulation of mitochondrial generation of oxidative stress.
authors.affiliation: Liver Unit, Instituto de Malalties Digestives, Hospital Clinic i Provincial, Instituto Investigaciones Biomédicas August Pi i Sunyer.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Lluis
authors.forename: Albert
authors.initials: A
authors.lastname: Morales
authors.forename: Carmen
authors.initials: C
authors.lastname: Blasco
authors.forename: Anna
authors.initials: A
authors.lastname: Colell
authors.forename: Montserrat
authors.initials: M
authors.lastname: Mari
authors.forename: Carmen
authors.initials: C
authors.lastname: Garcia-Ruiz
authors.forename: José C
authors.initials: JC
authors.lastname: Fernandez-Checa
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000502:physiology; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism*; D018197:Hepatoblastoma; D022781:Hepatocytes / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008113:Liver Neoplasms; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D005978:Glutathione