Mitochondrial CYP2E1 is sufficient to mediate oxidative stress and cytotoxicity induced by ethanol and acetaminophen.
Several cytochromes P450 (CYPs) are not only located in the endoplasmic reticulum but also within mitochondria. One such CYP is CYP2E1 which metabolizes numerous substrates and generates significant amount of reactive oxygen species. The presence of CYP2E1 in these organelles raises questions regarding its physiological role but also its possible deleterious effects in the context of drug-induced cytotoxicity. The aim of our study was to investigate the role of mitochondrial CYP2E1 in the toxicity of acetaminophen and ethanol. Hence the effects of these two compounds in cells expressing CYP2E1 in mitochondria only, or in both endoplasmic reticulum and mitochondria, were compared to those observed in mock-transfected cells. Our results indicated that when acetaminophen or ethanol were used as CYP2E1 substrates, the exclusive localization of CYP2E1 within mitochondria was sufficient to induce reactive oxygen species overproduction, depletion of reduced glutathione, increased expression of mitochondrial Hsp70, mitochondrial dysfunction and cytotoxicity. Importantly, these harmful events happened despite lower cellular level and activity of CYP2E1 when compared to cells expressing CYP2E1 in both endoplasmic reticulum and mitochondria, and this was particularly obvious with acetaminophen. Taken together, these data suggest that mitochondrial CYP2E1 could play a major role in drug-induced oxidative stress and cell demise.
INSERM, UMR991, Liver Metabolisms and Cancer, Rennes, France.
Laetitia
L
Knockaert
Véronique
V
Descatoire
Nathalie
N
Vadrot
Bernard
B
Fromenty
Marie-Anne
MA
Robin
D000082:Acetaminophen / Q000633:toxicity*; D018712:Analgesics, Non-Narcotic / Q000633:toxicity*; D000818:Animals; D019556:COS Cells; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D019392:Cytochrome P-450 CYP2E1 / Q000502:physiology*; D000431:Ethanol / Q000633:toxicity*; D005978:Glutathione / Q000032:analysis; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D018384:Oxidative Stress; D010101:Oxygen Consumption / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000032:analysis
D018712:Analgesics, Non-Narcotic; D018840:HSP70 Heat-Shock Proteins; D017382:Reactive Oxygen Species; D000082:Acetaminophen; D000431:Ethanol; D019392:Cytochrome P-450 CYP2E1; D013482:Superoxide Dismutase; D005978:Glutathione