Peroxynitrite modulates MnSOD gene expression in lung epithelial cells.
Peroxynitrite (ONOO-) is a strong oxidant derived from nitric oxide ('NO) and superoxide (O2.-), reactive nitrogen (RNS) and oxygen species (ROS) present in inflamed tissue. Other oxidant stresses, e.g., TNF-alpha and hyperoxia, induce mitochondrial, manganese-containing superoxide dismutase (MnSOD) gene expression. These experiments tested whether ONOO regulated MnSOD gene expression in human lung epithelial (A549) cells. 3-morpholinosydnonimine HCI (SIN-1) (10 or 1000 microM) increased MnSOD mRNA, but did not change hypoxanthine guanine phosphoribosyl transferase (HPRT) mRNA. Authentic peroxynitrite (ONOO ) (100-500 microM) also increased MnSOD mRNA but did not change constitutive HPRT mRNA expression. ONOO stimulated luciferase gene expression driven by a 2.5 kb fragment of the rat MnSOD gene 5' promoter region. MnSOD gene induction due to ONOO- was inhibited effectively by L-cysteine (10 mM) and partially inhibited by N-acetyl cysteine (50 mM) or pyrrole dithiocarbamate (10 mM). .NO from 1-propanamine, 3-(2-hydroxy-2-nitroso-1-propylhydrazine) (PAPA NONOate) (100 or 1000 microM) did not change MnSOD or HPRT mRNA. Neither H202 nor NO2-, breakdown products of SIN-1 and ONOO , had any effect on MnSOD mRNA expression; however, ONOO- and SIN-1 did not increase MnSOD protein content detectable by western blots, nor did they increase MnSOD enzymatic activity. Increased steady state [O2.-] in the presence of .NO yields ONOO , and ONOO has direct, stimulatory effects on MnSOD transcript expression.
Jackson
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RM
Birmingham VA Medical Center and University of Alabama at Birmingham, 35294-0006, USA. rjackson@uab.edu
Parish
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Helton
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D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D004847:Epithelial Cells / Q000201:enzymology; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008156:Luciferases / Q000235:genetics; D008168:Lung / Q000201:enzymology*; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009566:Nitrates / Q000494:pharmacology*; D009569:Nitric Oxide / Q000494:pharmacology; D009573:Nitrites / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics*
D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C039642:peroxynitric acid; D009569:Nitric Oxide; C002385:linsidomine; D006861:Hydrogen Peroxide; D008981:Molsidomine; D008156:Luciferases; D013482:Superoxide Dismutase