title: α-Synuclein protects against manganese neurotoxic insult during the early stages of exposure in a dopaminergic cell model of Parkinson's disease.
abstract: The pathological role of α-synuclein (α-Syn) aggregation in neurodegeneration is well recognized, but the physiological function of normal α-Syn remains unknown. As α-Syn protein contains multiple divalent metal binding sites, herein we conducted a comprehensive characterization of the role of α-Syn in manganese-induced dopaminergic neurotoxicity. We established transgenic N27 dopaminergic neuronal cells by stably expressing human wild-type α-Syn at normal physiological levels. α-Syn-expressing dopaminergic cells significantly attenuated Mn-induced neurotoxicity for 24-h exposures relative to vector control cells. To further explore cellular mechanisms, we studied the mitochondria-dependent apoptotic pathway. Analysis of a key mitochondrial apoptotic initiator, cytochrome c, revealed that α-Syn significantly reduces the Mn-induced cytochrome c release into cytosol. The downstream caspase cascade, involving caspase-9 and caspase-3 activation, during Mn exposure was also largely attenuated in Mn-treated α-Syn cells in a time-dependent manner. α-Syn cells also showed a dramatic reduction in the Mn-induced proteolytic activation of the pro-apoptotic kinase PKCδ. The generation of Mn-induced reactive oxygen species (ROS) did not differ between α-Syn and vector control cells, indicating that α-Syn exerts its protective effect independent of altering ROS generation. Inductively coupled plasma-mass spectrometry (ICP-MS) revealed no significant differences in intracellular Mn levels between treated vector and α-Syn cells. Notably, the expression of wild-type α-Syn in primary mesencephalic cells also rescued cells from Mn-induced neurotoxicity. However, prolonged exposure to Mn promoted protein aggregation in α-Syn-expressing cells. Collectively, these results demonstrate that wild-type α-Syn exhibits neuroprotective effects against Mn-induced neurotoxicity during the early stages of exposure in a dopaminergic neuronal model of PD.
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa 50011.
authors.forename: Dilshan S
authors.initials: DS
authors.lastname: Harischandra
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa 50011.
authors.forename: Huajun
authors.initials: H
authors.lastname: Jin
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa 50011.
authors.forename: Vellareddy
authors.initials: V
authors.lastname: Anantharam
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa 50011.
authors.forename: Arthi
authors.initials: A
authors.lastname: Kanthasamy
authors.affiliation: Department of Biomedical Sciences, Iowa Center for Advanced Neurotoxicology, Iowa State University, Ames, Iowa 50011 akanthas@iastate.edu.
authors.forename: Anumantha G
authors.initials: AG
authors.lastname: Kanthasamy
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001665:Binding Sites; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002712:Chlorides / Q000378:metabolism / Q000633:toxicity*; D053938:DNA Fragmentation / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D017895:Manganese Compounds / Q000378:metabolism; D020149:Manganese Poisoning / Q000150:complications / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control; D008636:Mesencephalon / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008959:Models, Neurological; D010300:Parkinson Disease / Q000209:etiology / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control; D011485:Protein Binding; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013054:Spectrophotometry, Atomic; D014162:Transfection; D051844:alpha-Synuclein / Q000235:genetics* / Q000378:metabolism
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; D017382:Reactive Oxygen Species; D051844:alpha-Synuclein; C025340:manganese chloride; D004298:Dopamine
keywords: Parkinson’s disease; metals; neuroprotection; neurotoxicity; protein aggregation; α-synuclein