title: Formation and Implications of Alpha-Synuclein Radical in Maneb- and Paraquat-Induced Models of Parkinson's Disease.
abstract: Parkinson's disease (PD) is a debilitating, progressive, neurodegenerative disorder characterized by progressive loss of dopaminergic neurons and motor deficits. Alpha-synuclein-containing aggregates represent a feature of a variety of neurodegenerative disorders, including PD; however, the mechanism that initiates and promotes intraneuronal alpha-synuclein aggregation remains unknown. We hypothesized protein radical formation as an initiating mechanism for alpha-synuclein aggregation. Therefore, we used the highly sensitive immuno-spin trapping technique to investigate protein radical formation as a possible mechanism of alpha-synuclein aggregation as well as to investigate the source of protein radical formation in the midbrains of Maneb- and paraquat-coexposed mice. Coexposure to Maneb and paraquat for 6 weeks resulted in active microgliosis, NADPH oxidase activation, and inducible nitric oxide synthase (iNOS) induction, which culminated in protein radical formation in the midbrains of mice. Results obtained with immuno-spin trapping and immunoprecipitation experiments confirmed formation of alpha-synuclein radicals in dopaminergic neurons of exposed mice. Free radical formation requires NADPH oxidase and iNOS, as indicated by decreased protein radical formation in knockout mice (P47phox(-/-) and iNOS(-/-)) and in mice treated with inhibitors such as FeTPPS (a peroxynitrite decomposition catalyst), 1400 W (an iNOS inhibitor), or apocynin (a NADPH oxidase inhibitor). Concurrence of protein radical formation with dopaminergic neuronal death indicated a link between protein radicals and disease progression. Taken together, these results show for the first time the formation and detection of the alpha-synuclein radical and suggest that NADPH oxidase and iNOS play roles in peroxynitrite-mediated protein radical formation and subsequent neuronal death in the midbrains of Maneb- and paraquat-coexposed mice.
authors.affiliation: Free Radical Metabolism Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA. kumara10@niehs.nih.gov.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Free Radical Metabolism Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
authors.forename: Fabian
authors.initials: F
authors.lastname: Leinisch
authors.affiliation: Free Radical Metabolism Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
authors.forename: Maria B
authors.initials: MB
authors.lastname: Kadiiska
authors.affiliation: Free Radical Metabolism Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
authors.forename: Jean
authors.initials: J
authors.lastname: Corbett
authors.affiliation: Free Radical Metabolism Group, Immunity, Inflammation, and Disease Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, 27709, USA.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Mason
mesh_terms: D000818:Animals; D003497:Cyclic N-Oxides / Q000378:metabolism; D004195:Disease Models, Animal; D059290:Dopaminergic Neurons / Q000378:metabolism; D007274:Injections, Intraperitoneal; D008297:Male; D008344:Maneb; D008636:Mesencephalon / Q000378:metabolism / Q000473:pathology; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000378:metabolism; D008954:Models, Biological; D019255:NADPH Oxidases / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D010269:Paraquat; D010300:Parkinson Disease / Q000378:metabolism* / Q000473:pathology*; D030421:Peroxynitrous Acid / Q000378:metabolism; D013113:Spin Labels; D013378:Substantia Nigra / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D051844:alpha-Synuclein / Q000378:metabolism*
chemical_list: D003497:Cyclic N-Oxides; D013113:Spin Labels; D051844:alpha-Synuclein; D008344:Maneb; D030421:Peroxynitrous Acid; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D052247:Nitric Oxide Synthase Type II; D014446:Tyrosine 3-Monooxygenase; D019255:NADPH Oxidases; D010269:Paraquat
keywords: DMPO; Immuno-spin trapping; Parkinson’s disease; Peroxynitrite; Protein radicals