title: The molecular mechanism of rotenone-induced α-synuclein aggregation: emphasizing the role of the calcium/GSK3β pathway.
abstract: Environmental toxin exposure is associated with the development of Parkinson's disease (PD), and environmental factors can influence the onset of the majority of sporadic PD cases via genetically mediated pathways. Rotenone, a widespread pesticide, induces Parkinsonism and the formation of Lewy bodies in animals; however, the molecular mechanism that underlies α-synuclein aggregation remains unclear. Here, we assessed the aggregation of α-synuclein in PC12 cells with or without cross-linking following rotenone exposure via a variety of methods, including western blotting, immunofluorescence and electron microscopy. We demonstrated that rotenone increased the intracellular calcium levels and induced the aggregation and phosphorylation of α-synuclein in a calcium-dependent manner. Aggregated α-synuclein is typically degraded by autophagy, and rotenone impaired this process. The attenuation of autophagy and α-synuclein alterations were reversed by scavenging calcium. Calcium regulates the activity of AKT-glycogen synthase kinase 3 (GSK3)β. We demonstrated that rotenone attenuated the phosphorylation of AKT and GSK3β, and the elimination of calcium reversed these phenomena. As a GSK3β inhibitor, lithium promoted autophagy and decreased the aggregation and phosphorylation of α-synuclein. GSK3β activation through overexpression depressed autophagy and increased the total protein level and phosphorylation of α-synuclein. These results suggest that rotenone-induced α-synuclein aggregation is mediated by the calcium/GSK3β signaling pathway.
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Neuroscience Center, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Xiannongtan Street, Xuanwu District, Beijing 100050, PR China.
authors.forename: Yu-He
authors.initials: YH
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Neuroscience Center, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Xiannongtan Street, Xuanwu District, Beijing 100050, PR China.
authors.forename: Wen-Fen
authors.initials: WF
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Neuroscience Center, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Xiannongtan Street, Xuanwu District, Beijing 100050, PR China.
authors.forename: Jian-Dong
authors.initials: JD
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Neuroscience Center, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Xiannongtan Street, Xuanwu District, Beijing 100050, PR China.
authors.forename: Ju-Yang
authors.initials: JY
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Neuroscience Center, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Xiannongtan Street, Xuanwu District, Beijing 100050, PR China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Mu
authors.affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Neuroscience Center, Department of Pharmacology, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Xiannongtan Street, Xuanwu District, Beijing 100050, PR China. Electronic address: chennh@imm.ac.cn.
authors.forename: Nai-Hong
authors.initials: NH
authors.lastname: Chen
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D038362:Glycogen Synthase Kinase 3 / Q000187:drug effects*; D000071679:Glycogen Synthase Kinase 3 beta; D007306:Insecticides / Q000037:antagonists & inhibitors / Q000633:toxicity*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008845:Microinjections; D016716:PC12 Cells; D051381:Rats; D012402:Rotenone / Q000037:antagonists & inhibitors / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects; D013378:Substantia Nigra; D014475:Uncoupling Agents / Q000633:toxicity*; D051844:alpha-Synuclein / Q000187:drug effects*
chemical_list: D007306:Insecticides; D014475:Uncoupling Agents; D051844:alpha-Synuclein; D012402:Rotenone; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3; D002118:Calcium
keywords: Calcium; GSK3β; Parkinson’s disease; Rotenone; α-Synuclein