Antioxidant enzyme inhibitors enhance peroxynitrite-induced cell death in U937 cells
- 108 Downloads
Peroxynitrite, a potent physiological inorganic toxin, is known to play a critical role in cellular oxidative damage. The protective role of antioxidant enzymes against peroxynitrite-induced oxidative damage in U937 cells was investigated in control and cells pre-treated with diethyldithiocarbamic acid, aminotriazole, and oxlalomalate, specific inhibitors of superoxide dismutase, catalase, and NADP+-dependent isocitrate dehydrogenase, respectively. Upon exposure to 1 mM 3-morpholinosydnomine N-ethylcarbamide (SIN-1), a generator of peroxynitrite through the reaction between nitric oxide and superoxide anion, to U937 cells, the viability was lower and the protein oxidation, lipid peroxidation and oxidative DNA damage reflected by an increase in 8-hydroxy-2′-deoxyguanosine, were higher in the inhibitor-treated cells as compared to the control cells. We also observed the significant increase in the endogenous production of reactive oxygen species, as measured by the oxidation of 2′7′-dichlorodihydrofluorescin as well as the significant decrease in the intracellular GSH level in the inhibitor-treated U937 cells upon exposure to SIN-1. These results suggest that antioxidant enzymes play an important role in cellular defense against peroxynitrite-induced cell death.
KeywordsPeroxynitrite Antioxidant enzymes Cell death Redox status
This work was supported by grants from the Korea Science and Engineering Foundation (R05-2003-000-10027-0 and R01-2004-000-10328-0).
- 12.Halliwell B, Gutteridge JMC (1999) Free Radicals in Biology and Medicine, Oxford PressGoogle Scholar
- 14.Di Matteo MA, Loweth AC, Thomas S, Mabley JG, Morgan NG, Thorpe JR, Green IC (1997) Superoxide, nitric oxide, peroxynitrite and cytokine combinations all cause functional impairment and morphological changes in rat islets of Langerhans and insulin secreting cell lines, but dictate cell death by different mechanisms. Apoptosis 2:164–177PubMedCrossRefGoogle Scholar
- 21.Jo SH, Son MK, Koh HJ, Lee SM, Song IH, Kim YO, Lee YS, Jeong KS, Kim WB, Park JW, Song BJ, Huh TL (2001) Control of mitochondrial redox balance and cellular defense against oxidative damage by mitochondrial NADP+-dependent isocitrate dehydrogenase. J Biol Chem 276:16168–16176PubMedCrossRefGoogle Scholar
- 23.Beuge JA, Aust SD (1978) Microsomal lipid peroxidation. Methods Enzymol 52:302–310Google Scholar