Contribution of glutathione status to oxidant-induced mitochondrial DNA damage in colonic epithelial cells

Free Radic Biol Med. 2009 Oct 15;47(8):1190-8. doi: 10.1016/j.freeradbiomed.2009.07.032. Epub 2009 Aug 6.

Abstract

Although oxidative stress induces mitochondrial DNA (mtDNA) damage, a role for redox in modulating mtDNA oxidation and repair is relatively unexplored. This study examines the contribution of cellular glutathione (GSH) redox status to menadione (MQ)-induced mtDNA damage and postoxidant mtDNA recovery in a nontransformed NCM460 colonic cell line. We show that MQ caused dose-dependent increases in mtDNA damage that were blunted by N-acetylcysteine, a thiol antioxidant. Damage to mtDNA paralleled mitochondrial protein disulfide formation and glutathione disulfide increases in the cytosol and mitochondria and was exacerbated by inhibition of GSH synthesis in accordance with decreased cytosolic and mitochondrial GSH. Blockade of mitochondrial GSH (mtGSH) transport potentiated mtDNA damage, which was prevented by overexpression of the oxoglutarate mtGSH carrier, underscoring a link between mtGSH and mtDNA responsiveness to oxidative stress. The removal of MQ posttreatment elicited mtDNA recovery to basal levels by 4 h, indicating complete repair. Notably, mtDNA recovery was preceded by restored cytosolic and mtGSH levels at 2 h, suggesting a connection between the maintenance of cell GSH and effective mtDNA repair. The MQ-induced dose-dependent increase in mtDNA damage was attenuated by overexpressing mitochondrial 8-oxoguanine DNA glycosylase (Ogg1), consistent with 7,8-dihydro-8-oxoguanine being a major oxidative mtDNA lesion. Collectively, the results show that oxidative mtDNA damage in colonic cells is highly responsive to the mtGSH status and that postoxidant mtDNA recovery may also be GSH sensitive.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cells, Cultured
  • Colon / drug effects*
  • Colon / metabolism*
  • DNA Damage*
  • DNA Glycosylases / metabolism
  • DNA, Mitochondrial / genetics*
  • Epithelial Cells / metabolism
  • Glutathione / metabolism*
  • Glutathione Disulfide / metabolism
  • Guanine / analogs & derivatives
  • Guanine / metabolism
  • Humans
  • Oxidants / pharmacology*
  • Oxidation-Reduction
  • Vitamin K 3 / pharmacology

Substances

  • 7,8-dihydro-8-oxoguanine
  • DNA, Mitochondrial
  • Oxidants
  • Guanine
  • Vitamin K 3
  • DNA Glycosylases
  • oxoguanine glycosylase 1, human
  • Glutathione
  • Glutathione Disulfide