Two essential but distinct functions of the mammalian abasic endonuclease

Tadahide Izumi, David B. Brown, C. V. Naidu, Kishor K. Bhakat, Mark A. MacInnes, Hiroshi Saito, David J. Chen, Sankar Mitra

Research output: Contribution to journalArticlepeer-review

192 Scopus citations


The mammalian abasic endonuclease, APE1, has two distinct roles in the repair of oxidative DNA damage and in gene regulation. Here we show that both functions are essential for cell survival. Deletion of the APE1 gene causes embryonic lethality in mice, and no nullizygous embryo fibroblasts have been isolated. We have now established nullizygous embryo fibroblast lines from APE1-/- mouse embryos that are transgenic with the "floxed" human APE1 (hAPE1) gene. Removal of hAPE1 by Cre expression through nuclear microinjection elicited apoptosis in these cells within 24 h, which was blocked by coinjection of the wild-type hAPE1 gene. In contrast, mutant hPE1 alleles, lacking either the DNA repair or acetylation-mediated gene regulatory function, could not prevent apoptosis, although the combination of these two mutants complemented APE deficiency induced by Cre. These results indicate that distinct and separable functions of APE1 are both essential for mammalian cells even in vitro and provide the evidence that mammalian cells, unlike yeast or Escherichia coli, absolutely require APE for survival, presumably to protect against spontaneous oxidative DNA damage.

Original languageEnglish (US)
Pages (from-to)5739-5743
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Apr 19 2005
Externally publishedYes


  • Base excision repair
  • Conditional gene inactivation
  • DNA repair
  • Endogenous DNA damage

ASJC Scopus subject areas

  • General


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