Characterization of antioxidant properties of natural killer-enhancing factor-B and induction of its expression by hydrogen peroxide.
Natural killer-enhancing factor B (NKEF-B) belongs to a highly conserved family of recently discovered antioxidants. The role of NKEF-B as an antioxidant was demonstrated by its protection of transfected cells to oxidative damage by hydrogen peroxide. To further characterize the antioxidant properties of NKEF-B, we compared the sensitivity of a human endothelial cell line ECV304 and its transfectant, B/1 that hyperexpresses NKEF-B, to various oxidants. In addition, we investigated the changes in the expression of NKEF-B mRNA upon oxidative stress. We found that B/1 was significantly more resistant than the control cells to the oxidative stresses caused by t-butyl hydroperoxide (t-BHP) and methyl mercury (MeHg). In contrast, there was no difference in the sensitivity of B/1 and the control cells to sulfhydryl reactive agents, diethyl maleate and diamide. B/1 was also as sensitive as the control cells to buthionine sulfoximine. The expression of NKEF-B mRNA was induced when the parental cell line ECV304 was treated with 2 mm HP. The induction reached a maximum level around 2 hr and decreased to the basal level around 4 hr. NKEF-A mRNA was not induced by HP. These results demonstrate antioxidant activities of NKEF-B toward prooxidants such as alkyl hydroperoxide and MeHg. Together with its antioxidant activity, the induction of NKEF-B by HP indicates that NKEF-B is an important oxidative stress protein providing protection against a variety of xenobiotic toxic agents.
Kim
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Division of Surgical Oncology, UCLA School of Medicine, Los Angeles, California 90095, USA.
Sarafian
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TA
Shau
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H
D000975:Antioxidants / Q000494:pharmacology*; D001798:Blood Proteins / Q000235:genetics / Q000494:pharmacology*; D015152:Blotting, Northern; D019328:Buthionine Sulfoximine / Q000633:toxicity; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic; D004730:Endothelium, Vascular / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000633:toxicity; D005786:Gene Expression Regulation / Q000187:drug effects; D006360:Heat-Shock Proteins; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008767:Methylmercury Compounds / Q000633:toxicity; D016877:Oxidants / Q000633:toxicity*; D018384:Oxidative Stress; D010544:Peroxidases; D010545:Peroxides / Q000633:toxicity; D054464:Peroxiredoxins; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species; D013439:Sulfhydryl Reagents / Q000633:toxicity; D014162:Transfection; D014470:Umbilical Cord; D020122:tert-Butylhydroperoxide
D000975:Antioxidants; D001798:Blood Proteins; D004791:Enzyme Inhibitors; D006360:Heat-Shock Proteins; D008767:Methylmercury Compounds; D016877:Oxidants; D010545:Peroxides; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013439:Sulfhydryl Reagents; D019328:Buthionine Sulfoximine; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D010544:Peroxidases; C086065:PRDX2 protein, human; D054464:Peroxiredoxins