title: Peroxynitrite-induced mitochondrial and endonuclease-mediated nuclear DNA damage in acetaminophen hepatotoxicity.
abstract: Intracellular sources of peroxynitrite formation and potential targets for this powerful oxidant and nitrating agent have not been identified after acetaminophen (AAP) overdose. Therefore, we tested the hypothesis that peroxynitrite generated in mitochondria may be responsible for mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) damage. C3Heb/FeJ mice were treated with 300 mg/kg AAP and monitored for up to 12 h. Loss of mtDNA (assayed by slot blot hybridization) and substantial nDNA fragmentation (evaluated by anti-histone enzyme-linked immunosorbent assay, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and agarose gel electrophoresis) were observed as early as 3 h after AAP overdose. Analysis of nitrotyrosine protein adducts in subcellular fractions established that peroxynitrite was generated predominantly in mitochondria beginning at 1 h after AAP injection. Delayed treatment with a bolus dose of glutathione (GSH) accelerated the recovery of mitochondrial glutathione, which then effectively scavenged peroxynitrite. However, mtDNA loss was only partially prevented. Despite the absence of nitrotyrosine adducts in the nucleus after AAP overdose, nDNA damage was almost completely eliminated with GSH administration. A direct comparison of nDNA damage after AAP overdose with nDNA fragmentation during tumor necrosis factor receptor-mediated apoptosis showed similar DNA ladders on agarose gels but quantitatively different results in three other assays. We conclude that peroxynitrite may be partially responsible for mtDNA loss but is not directly involved in nDNA damage. In contrast, nDNA fragmentation after AAP overdose is not caused by caspase-activated DNase but most likely by other intracellular DNase(s), whose activation is dependent on the mitochondrial oxidant stress and peroxynitrite formation.
authors.affiliation: Liver Research Institute, College of Medicine, University of Arizona, Tucson, 85724, USA.
authors.forename: Cathleen
authors.initials: C
authors.lastname: Cover
authors.forename: Abdellah
authors.initials: A
authors.lastname: Mansouri
authors.forename: Tamara R
authors.initials: TR
authors.lastname: Knight
authors.forename: Mary Lynn
authors.initials: ML
authors.lastname: Bajt
authors.forename: John J
authors.initials: JJ
authors.lastname: Lemasters
authors.forename: Dominique
authors.initials: D
authors.lastname: Pessayre
authors.forename: Hartmut
authors.initials: H
authors.lastname: Jaeschke
mesh_terms: D000082:Acetaminophen / Q000633:toxicity*; D018712:Analgesics, Non-Narcotic / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology; D056486:Chemical and Drug Induced Liver Injury / Q000201:enzymology / Q000473:pathology*; D004249:DNA Damage / Q000187:drug effects*; D053938:DNA Fragmentation / Q000187:drug effects; D004272:DNA, Mitochondrial / Q000187:drug effects; D004720:Endonucleases / Q000378:metabolism*; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000201:enzymology; D030421:Peroxynitrous Acid / Q000378:metabolism / Q000633:toxicity*; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
chemical_list: D018712:Analgesics, Non-Narcotic; D004272:DNA, Mitochondrial; D014409:Tumor Necrosis Factor-alpha; D030421:Peroxynitrous Acid; D000082:Acetaminophen; D004720:Endonucleases