title: Apoptosis-inducing factor modulates mitochondrial oxidant stress in acetaminophen hepatotoxicity.
abstract: Acetaminophen (APAP) overdose causes liver injury in humans and mice. DNA fragmentation is a hallmark of APAP-induced cell death, and nuclear translocation of apoptosis-inducing factor (AIF) correlates with DNA fragmentation after APAP overdose. To test the hypothesis that AIF may be a critical mediator of APAP-induced cell death, fasted male AIF-deficient Harlequin (Hq) mice and respective wild-type (WT) animals were treated with 200 mg/kg APAP. At 6 h after APAP, WT animals developed severe liver injury as indicated by the increase in plasma alanine aminotransferase (ALT) activities (8600 ± 1870 U/l) and 61 ± 8% necrosis. This injury was accompanied by massive DNA strand breaks in centrilobular hepatocytes (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling [TUNEL] assay) and release of DNA fragments into the cytosol (anti-histone ELISA). In addition, there was formation of reactive oxygen (increase in liver glutathione disulfide (GSSG) levels and mitochondrial protein carbonyls) and peroxynitrite (nitrotyrosine [NT] staining) together with mitochondrial translocation of activated c-jun-N-terminal kinase (P-JNK) and release of AIF from the mitochondria. In contrast, Hq mice had significantly less liver injury (ALT: 330 ± 130 U/l; necrosis: 4 ± 2%), minimal nuclear DNA damage, and drastically reduced oxidant stress (based on all parameters) at 6 h. WT and Hq mice had the same baseline levels of cyp2E1 and of glutathione. The initial depletion of glutathione (20 min after APAP) was the same in both groups suggesting that there was no relevant difference in metabolic activation of APAP. Thus, AIF has a critical function in APAP hepatotoxicity by facilitating generation of reactive oxygen in mitochondria and, after nuclear translocation, AIF can be involved in DNA fragmentation.
authors.affiliation: Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
authors.forename: Mary Lynn
authors.initials: ML
authors.lastname: Bajt
authors.forename: Anup
authors.initials: A
authors.lastname: Ramachandran
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Yan
authors.forename: Margitta
authors.initials: M
authors.lastname: Lebofsky
authors.forename: Anwar
authors.initials: A
authors.lastname: Farhood
authors.forename: John J
authors.initials: JJ
authors.lastname: Lemasters
authors.forename: Hartmut
authors.initials: H
authors.lastname: Jaeschke
mesh_terms: D000082:Acetaminophen / Q000633:toxicity*; D000818:Animals; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D015153:Blotting, Western; D056486:Chemical and Drug Induced Liver Injury / Q000473:pathology*; D053938:DNA Fragmentation; D062787:Drug Overdose; D019803:Glutathione Disulfide / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000187:drug effects / Q000473:pathology; D008297:Male; D051379:Mice; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D009336:Necrosis / Q000139:chemically induced / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D030421:Peroxynitrous Acid / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D051033:Apoptosis Inducing Factor; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D000082:Acetaminophen; D019803:Glutathione Disulfide