title: Adenovirus-mediated overexpression of catalase in the cytosolic or mitochondrial compartment protects against toxicity caused by glutathione depletion in HepG2 cells expressing CYP2E1.
abstract: Induction of cytochrome P450 CYP2E1 by ethanol appears to be one of the mechanisms by which ethanol creates a state of oxidative stress. Glutathione (GSH) is a key cellular antioxidant that detoxifies reactive oxygen species. Depletion of GSH, especially mitochondrial GSH, is believed to play a role in the ethanol-induced liver injury. Previous results reported that depletion of GSH by buthionine-(S,R)-sulfoximine (BSO) treatment caused apoptosis and necrosis in HepG2 cells, which overexpress CYP2E1. In the current work, adenoviral infection with vectors that resulted in expression of catalase either in the cytosol or mitochondrial compartments was able to abolish the loss of mitochondrial membrane potential or damage to mitochondria observed in HepG2 cells overexpressing CYP2E1 that were treated with BSO. Loss of cell viability, either necrotic or apoptotic, was also prevented by the catalase overexpression after infection with the adenoviral vectors. The protective effects of catalase were associated with the suppression of the increase in the production of reactive oxygen species and of mitochondrial lipid peroxidation observed after GSH depletion. These results reveal a prominent role for H(2)O(2) as a mediator in the cytotoxicity observed after depletion of GSH in HepG2 cells overexpressing CYP2E1. Damage to mitochondria may be a critical step for cellular toxicity by CYP2E1-derived reactive oxygen species.
authors.affiliation: Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, New York 10029, USA.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Marí
authors.forename: Jingxiang
authors.initials: J
authors.lastname: Bai
authors.forename: Arthur I
authors.initials: AI
authors.lastname: Cederbaum
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002374:Catalase / Q000096:biosynthesis* / Q000235:genetics; D019392:Cytochrome P-450 CYP2E1 / Q000096:biosynthesis* / Q000235:genetics; D003600:Cytosol / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005822:Genetic Vectors; D005978:Glutathione / Q000502:physiology*; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000201:enzymology*; D010101:Oxygen Consumption / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013778:Tetrazolium Salts; D013844:Thiazoles; D014407:Tumor Cells, Cultured
chemical_list: D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D019328:Buthionine Sulfoximine; D002374:Catalase; D019392:Cytochrome P-450 CYP2E1; C022616:thiazolyl blue; D005978:Glutathione