Nuclear translocation of endonuclease G and apoptosis-inducing factor during acetaminophen-induced liver cell injury

Mary Lynn Bajt, Cathleen Cover, John J. Lemasters, Hartmut Jaeschke

Research output: Contribution to journalArticle

134 Scopus citations

Abstract

Mitochondrial dysfunction and internucleosomal DNA fragmentation are well-recognized features of acetaminophen (AAP)-induced hepatocyte cell death. However, the endonucleases responsible for this effect have not been identified. Apoptosis-inducing factor (AIF) and endonuclease G are nucleases located in the intermembrane space of mitochondria. AIF is thought to trigger chromatin condensation and induce cleavage of DNA into high molecular weight fragments (50-300 kb), and endonuclease G can produce oligonucleosomal DNA fragments. Therefore, the objective of this investigation was to test the hypothesis that endonuclease G and AIF could be involved in AAP-induced nuclear DNA fragmentation. Using immunofluorescence microscopy, it was shown that in primary cultured mouse hepatocytes, endonuclease G and AIF translocated to the nucleus between 3 and 6 h after exposure to 5 mM AAP. In contrast, other mitochondrial intermembrane proteins such as cytochrome c or the second mitochondria-derived activator of caspases (Smac) did not accumulate in the nucleus. The translocation of AIF and endonuclease G correlated with mitochondrial dysfunction as indicated by the progressive loss of the mitochondrial membrane potential (measured with the JC-1 assay) and the appearance of nuclear DNA fragments in the cytosol (determined by an anti-histone ELISA). Pretreatment with 20mM N-acetylcysteine prevented mitochondrial dysfunction, the nuclear translocation of endonuclease G and AIF, and the nuclear DNA fragmentation. The data support the conclusion that endonuclease G and AIF translocate to the nucleus in response to AAP-induced mitochondrial dysfunction and may be responsible, at least in part, for the initial DNA fragmentation during AAP hepatotoxicity.

Original languageEnglish (US)
Pages (from-to)217-225
Number of pages9
JournalToxicological Sciences
Volume94
Issue number1
DOIs
StatePublished - Nov 1 2006

Keywords

  • Acetaminophen hepatotoxicity
  • Cultured hepatocytes
  • DNA fragmentation
  • Endonucleases
  • N-acetylcysteine

ASJC Scopus subject areas

  • Toxicology

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