title: Regulation by mitochondrial superoxide and NADPH oxidase of cellular formation of nitrated cyclic GMP: potential implications for ROS signalling.
abstract: 8-Nitro-cGMP (8-nitroguanosine 3',5'-cyclic monophosphate) is a nitrated derivative of cGMP, which can function as a unique electrophilic second messenger involved in regulation of an antioxidant adaptive response in cells. In the present study, we investigated chemical and biochemical regulatory mechanisms involved in 8-nitro-cGMP formation, with particular focus on the roles of ROS (reactive oxygen species). Chemical analyses demonstrated that peroxynitrite-dependent oxidation and myeloperoxidase-dependent oxidation of nitrite in the presence of H2O2 were two major pathways for guanine nucleotide nitration. Among the guanine nucleotides examined, GTP was the most sensitive to peroxynitrite-mediated nitration. Immunocytochemical and tandem mass spectrometric analyses revealed that formation of 8-nitro-cGMP in rat C6 glioma cells stimulated with lipopolysaccharide plus pro-inflammatory cytokines depended on production of both superoxide and H2O2. Using the mitochondria-targeted chemical probe MitoSOX Red, we found that mitochondria-derived superoxide can act as a direct determinant of 8-nitro-cGMP formation. Furthermore, we demonstrated that Nox2 (NADPH oxidase 2)-generated H2O2 regulated mitochondria-derived superoxide production, which suggests the importance of cross-talk between Nox2-dependent H2O2 production and mitochondrial superoxide production. The results of the present study suggest that 8-nitro-cGMP can serve as a unique second messenger that may be implicated in regulating ROS signalling in the presence of NO.
authors.affiliation: Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
authors.forename: Khandaker Ahtesham
authors.initials: KA
authors.lastname: Ahmed
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Sawa
authors.forename: Hideshi
authors.initials: H
authors.lastname: Ihara
authors.forename: Shingo
authors.initials: S
authors.lastname: Kasamatsu
authors.forename: Jun
authors.initials: J
authors.lastname: Yoshitake
authors.forename: Md Mizanur
authors.initials: MM
authors.lastname: Rahaman
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Okamoto
authors.forename: Shigemoto
authors.initials: S
authors.lastname: Fujii
authors.forename: Takaaki
authors.initials: T
authors.lastname: Akaike
mesh_terms: D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000818:Animals; D045744:Cell Line, Tumor; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism; D051381:Rats; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism*
chemical_list: C525106:8-nitroguanosine 3',5'-cyclic monophosphate; D008070:Lipopolysaccharides; D009589:Nitrogen Oxides; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D012402:Rotenone; D013481:Superoxides; D030421:Peroxynitrous Acid; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D006152:Cyclic GMP