Aag-initiated base excision repair promotes ischemia reperfusion injury in liver, brain, and kidney

Proc Natl Acad Sci U S A. 2014 Nov 11;111(45):E4878-86. doi: 10.1073/pnas.1413582111. Epub 2014 Oct 27.


Inflammation is accompanied by the release of highly reactive oxygen and nitrogen species (RONS) that damage DNA, among other cellular molecules. Base excision repair (BER) is initiated by DNA glycosylases and is crucial in repairing RONS-induced DNA damage; the alkyladenine DNA glycosylase (Aag/Mpg) excises several DNA base lesions induced by the inflammation-associated RONS release that accompanies ischemia reperfusion (I/R). Using mouse I/R models we demonstrate that Aag(-/-) mice are significantly protected against, rather than sensitized to, I/R injury, and that such protection is observed across three different organs. Following I/R in liver, kidney, and brain, Aag(-/-) mice display decreased hepatocyte death, cerebral infarction, and renal injury relative to wild-type. We infer that in wild-type mice, Aag excises damaged DNA bases to generate potentially toxic abasic sites that in turn generate highly toxic DNA strand breaks that trigger poly(ADP-ribose) polymerase (Parp) hyperactivation, cellular bioenergetics failure, and necrosis; indeed, steady-state levels of abasic sites and nuclear PAR polymers were significantly more elevated in wild-type vs. Aag(-/-) liver after I/R. This increase in PAR polymers was accompanied by depletion of intracellular NAD and ATP levels plus the translocation and extracellular release of the high-mobility group box 1 (Hmgb1) nuclear protein, activating the sterile inflammatory response. We thus demonstrate the detrimental effects of Aag-initiated BER during I/R and sterile inflammation, and present a novel target for controlling I/R-induced injury.

Keywords: Aag/Mpg DNA glycosylase; DNA repair; base excision; ischemia reperfusion; liver.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Kidney Injury / enzymology
  • Acute Kidney Injury / genetics
  • Acute Kidney Injury / pathology
  • Animals
  • Brain / enzymology*
  • Brain / pathology
  • Brain Infarction / enzymology
  • Brain Infarction / genetics
  • Brain Infarction / pathology
  • Cell Death
  • DNA Damage
  • DNA Glycosylases / genetics
  • DNA Glycosylases / metabolism*
  • DNA Repair*
  • Enzyme Induction / genetics
  • HMGB1 Protein / genetics
  • HMGB1 Protein / metabolism
  • Hepatocytes / enzymology
  • Hepatocytes / pathology
  • Inflammation / enzymology
  • Inflammation / genetics
  • Inflammation / pathology
  • Kidney / enzymology*
  • Kidney / pathology
  • Liver / enzymology*
  • Liver / pathology
  • Mice
  • Mice, Knockout
  • Poly(ADP-ribose) Polymerases / genetics
  • Poly(ADP-ribose) Polymerases / metabolism
  • Reactive Nitrogen Species / metabolism
  • Reactive Oxygen Species / metabolism
  • Reperfusion Injury / enzymology*
  • Reperfusion Injury / genetics
  • Reperfusion Injury / pathology


  • HMGB1 Protein
  • HMGB1 protein, mouse
  • Reactive Nitrogen Species
  • Reactive Oxygen Species
  • Poly(ADP-ribose) Polymerases
  • 3-methyladenine-DNA glycosylase
  • DNA Glycosylases