title: Expression of mutant alpha-synucleins enhances dopamine transporter-mediated MPP+ toxicity in vitro.
abstract: Mutations in the alpha-synuclein gene (A30P and A53T) are reported to cause familial Parkinson's disease (PD), but it is not known how they result in selective dopaminergic cell death. Here we report on effects of mutant alpha-synucleins on dopamine transporter (DAT)-mediated toxicity of the selective dopaminergic neurotoxin 1-methyl-4-phenylpyridinium ion (MPP+) in vitro. We established human embryonic kidney HEK-293 cell lines stably co-expressing each alpha-synuclein isoform and the human DAT. We demonstrate that expression of all alpha-synuclein isoforms enhances toxicity of general complex I inhibition (rotenone), but only the expression of mutant alpha-synucleins induces significant increased DAT-dependent toxicity of very low concentrations of MPP+ compared to wild-type protein. Proteasomal inhibition by lactacystin does not alter MPP+-toxicity in all cell lines. Our data suggest a new mechanism of MPP+-induced dopaminergic toxicity by an interaction between mutant alpha-synucleins and the DAT, which is independent of the function of the proteasome.
authors.affiliation: Department of Neurology, University of Ulm, Oberer Eselsberg 45, 89081 Ulm, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Lehmensiek
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Tan
authors.forename: Johannes
authors.initials: J
authors.lastname: Schwarz
authors.forename: Alexander
authors.initials: A
authors.lastname: Storch
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000633:toxicity*; D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002460:Cell Line; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D050483:Dopamine Plasma Membrane Transport Proteins; D015870:Gene Expression / Q000502:physiology; D006540:Herbicides / Q000633:toxicity*; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000166:cytology; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors; D016296:Mutagenesis / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D012402:Rotenone / Q000494:pharmacology; D051843:Synucleins; D014162:Transfection; D014475:Uncoupling Agents / Q000494:pharmacology; D051844:alpha-Synuclein
chemical_list: D015853:Cysteine Proteinase Inhibitors; D050483:Dopamine Plasma Membrane Transport Proteins; D006540:Herbicides; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009097:Multienzyme Complexes; D009419:Nerve Tissue Proteins; C493214:SLC6A3 protein, human; C497604:SNCA protein, human; D051843:Synucleins; D014475:Uncoupling Agents; D051844:alpha-Synuclein; D012402:Rotenone; C067713:lactacystin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D015655:1-Methyl-4-phenylpyridinium; D000111:Acetylcysteine