title: Extracellular dopamine potentiates mn-induced oxidative stress, lifespan reduction, and dopaminergic neurodegeneration in a BLI-3-dependent manner in Caenorhabditis elegans.
abstract: Parkinson's disease (PD)-mimicking drugs and pesticides, and more recently PD-associated gene mutations, have been studied in cell cultures and mammalian models to decipher the molecular basis of PD. Thus far, a dozen of genes have been identified that are responsible for inherited PD. However they only account for about 8% of PD cases, most of the cases likely involving environmental contributions. Environmental manganese (Mn) exposure represents an established risk factor for PD occurrence, and both PD and Mn-intoxicated patients display a characteristic extrapyramidal syndrome primarily involving dopaminergic (DAergic) neurodegeneration with shared common molecular mechanisms. To better understand the specificity of DAergic neurodegeneration, we studied Mn toxicity in vivo in Caenorhabditis elegans. Combining genetics and biochemical assays, we established that extracellular, and not intracellular, dopamine (DA) is responsible for Mn-induced DAergic neurodegeneration and that this process (1) requires functional DA-reuptake transporter (DAT-1) and (2) is associated with oxidative stress and lifespan reduction. Overexpression of the anti-oxidant transcription factor, SKN-1, affords protection against Mn toxicity, while the DA-dependency of Mn toxicity requires the NADPH dual-oxidase BLI-3. These results suggest that in vivo BLI-3 activity promotes the conversion of extracellular DA into toxic reactive species, which, in turn, can be taken up by DAT-1 in DAergic neurons, thus leading to oxidative stress and cell degeneration.
authors.affiliation: Department of Pediatrics, Vanderbilt University, Nashville, Tennessee, United States of America.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Benedetto
authors.forename: Catherine
authors.initials: C
authors.lastname: Au
authors.forename: Daiana Silva
authors.initials: DS
authors.lastname: Avila
authors.forename: Dejan
authors.initials: D
authors.lastname: Milatovic
authors.forename: Michael
authors.initials: M
authors.lastname: Aschner
mesh_terms: D000375:Aging / Q000187:drug effects; D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D005110:Extracellular Space / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008017:Life Expectancy; D008297:Male; D008345:Manganese / Q000378:metabolism / Q000633:toxicity*; D009410:Nerve Degeneration; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010300:Parkinson Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D021381:Protein Transport
chemical_list: D029742:Caenorhabditis elegans Proteins; C532156:DAT-1 protein, C elegans; D050483:Dopamine Plasma Membrane Transport Proteins; D008345:Manganese; C544706:Bli-3 protein, C elegans; D010088:Oxidoreductases; D004298:Dopamine