BACKGROUND: (MRL)-lpr/lpr mice spontaneously develop autoimmune disease characterized by arthritis and glomerulonephritis. Nitric oxide is postulated to play a role in the disease pathogenesis, as mice treated with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (NMMA) show markedly reduced manifestations of the disease. The purpose of this study was to examine the role of peroxynitrite in disease development in MRL-lpr/lpr mice. MATERIALS AND METHODS: We examined kidney extracts from control and MRL-lpr/lpr mice for nitrotyrosine by immunoblot with a rabbit polyclonal anti-nitrotyrosine antibody. Catalase activity was determined spectrophotometrically or by activity staining of native polyacrylamide gels. In some experiments, we studied the ability of peroxynitrite and other agents to modify purified catalase in vitro. RESULTS: Kidney extracts from diseased mice had elevated levels of nitrotyrosine, and decreased levels of catalase activity and protein, relative to control mice. MRL-lpr/lpr mice treated with NMMA in vivo had decreased levels of nitrotyrosine, and demonstrated a partial restoration of both catalase activity and protein levels. Treatment of catalase in vitro with peroxynitrite or tetranitromethane at pH 8.0 resulted in protein nitration and a decrease in catalase activity. 1,3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, also decreased the activity of catalase. CONCLUSIONS: These observations suggest that peroxynitrite formation, with an associated decrease in catalase activity and general decrease in antioxidant enzyme activity, may result in increased levels of hydrogen peroxide and other oxidants that can contribute to the pathogenesis of disease in MRL-lpr/lpr mice.
BACKGROUND: (MRL)-lpr/lprmice spontaneously develop autoimmune disease characterized by arthritis and glomerulonephritis. Nitric oxide is postulated to play a role in the disease pathogenesis, as mice treated with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (NMMA) show markedly reduced manifestations of the disease. The purpose of this study was to examine the role of peroxynitrite in disease development in MRL-lpr/lprmice. MATERIALS AND METHODS: We examined kidney extracts from control and MRL-lpr/lprmice for nitrotyrosine by immunoblot with a rabbit polyclonal anti-nitrotyrosine antibody. Catalase activity was determined spectrophotometrically or by activity staining of native polyacrylamide gels. In some experiments, we studied the ability of peroxynitrite and other agents to modify purified catalase in vitro. RESULTS: Kidney extracts from diseased mice had elevated levels of nitrotyrosine, and decreased levels of catalase activity and protein, relative to control mice. MRL-lpr/lprmice treated with NMMA in vivo had decreased levels of nitrotyrosine, and demonstrated a partial restoration of both catalase activity and protein levels. Treatment of catalase in vitro with peroxynitrite or tetranitromethane at pH 8.0 resulted in protein nitration and a decrease in catalase activity. 1,3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, also decreased the activity of catalase. CONCLUSIONS: These observations suggest that peroxynitrite formation, with an associated decrease in catalase activity and general decrease in antioxidant enzyme activity, may result in increased levels of hydrogen peroxide and other oxidants that can contribute to the pathogenesis of disease in MRL-lpr/lprmice.
Authors: Vani Nilakantan; Xianghua Zhou; Gail Hilton; Allan M Roza; Mark B Adams; Christopher P Johnson; Galen M Pieper Journal: Mol Cell Biochem Date: 2005-02 Impact factor: 3.396
Authors: Ruslan Rafikov; Sanjiv Kumar; Saurabh Aggarwal; Yali Hou; Archana Kangath; Daniel Pardo; Jeffrey R Fineman; Stephen M Black Journal: Free Radic Biol Med Date: 2013-11-06 Impact factor: 7.376