The role of superoxide radical in TNF-alpha induced NF-kappaB activation
Wang, S.; Leonard, S.S.; Castranova, V.; Vallyathan, V.; Shi, X.
Annals of Clinical and Laboratory Science 29(3): 192-199
1999
ISSN/ISBN: 0091-7370 PMID: 10440583 Document Number: 510821
Electron spin resonance (ESR) spin trapping with 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO) was utilized to investigate the generation of oxygen free radicals from macrophages stimulated by tumor necrosis factor-alpha (TNF-alpha). TNF-alpha stimulated macrophages generated hydroxyl (cntdotOH) and superoxide anion (O2.-) radicals. Incubation of TNF-alpha with macrophages resulted in an activation of DNA binding activity of the nuclear transcription factor NF-kappaB. Superoxide dismutase (SOD), but not catalase or sodium formate, inhibited this NF-kappaB activation, suggesting that O2.- rather than H2O2 or cntdotOH, radicals play the most critical role in this induction. beta-Nicotinamide adenine dinucleotide phosphate (NADPH) did not affect the NF-kappaB activation, while allopurinol, an inhibitor of xanthine oxidase, repressed it, suggesting that xanthine/xanthine oxidase, and not NADPH dependent oxidase, may be a source of O2.- radicals which induce NF-kappaB activation. O2.- is generated via reduction of molecular oxygen by xanthine and xanthine oxidase, as demonstrated by the oxygen consumption assay. The results indicate that TNF-alpha induces oxygen radical generation from macrophages. O2.- seems to play a key role in TNF-alpha-induced NF-kappaB activation in macrophages. Xanthine and xanthine oxidase appears to be a source of O2.- radicals responsible for TNF-alpha-induced NF-kappaB activation.