title: α-Synuclein-induced mitochondrial dysfunction in isolated preparation and intact cells: implications in the pathogenesis of Parkinson's disease.
abstract: This study has shown that purified recombinant human α-synuclein (20 μM) causes membrane depolarization and loss of phosphorylation capacity of isolated purified rat brain mitochondria by activating permeability transition pore complex. In intact SHSY5Y (human neuroblastoma cell line) cells, lactacystin (5 μM), a proteasomal inhibitor, causes an accumulation of α-synuclein with concomitant mitochondrial dysfunction and cell death. The effects of lactacystin on intact SHSY5Y cells are, however, prevented by knocking down α-synuclein expression by specific siRNA. Furthermore, in wild-type (non-transfected) SHSY5Y cells, the effects of lactacystin on mitochondrial function and cell viability are also prevented by cyclosporin A (1 μM) which blocks the activity of the mitochondrial permeability transition pore. Likewise, in wild-type SHSY5Y cells, typical mitochondrial poison like antimycin A (50 nM) produces loss of cell viability comparable to that of lactacystin (5 μM). These data, in combination with those from isolated brain mitochondria, strongly suggest that intracellularly accumulated α-synuclein can interact with mitochondria in intact SHSY5Y cells causing dysfunction of the organelle which drives the cell death under our experimental conditions. The results have clear implications in the pathogenesis of sporadic Parkinson's disease. α-Synuclein is shown to cause mitochondrial impairment through interaction with permeability transition pore complex in isolated preparations. Intracellular accumulation of α-synuclein in SHSY5Y cells following proteasomal inhibition leads to mitochondrial impairment and cell death which could be prevented by knocking down α-synuclein gene. The results link mitochondrial dysfunction and α-synuclein accumulation, two key pathogenic mechanisms of Parkinson's disease, in a common damage pathway.
authors.affiliation: Department of Biochemistry, Institute of Post Graduate Medical Education and Research, Kolkata, India.
authors.forename: Aritri
authors.initials: A
authors.lastname: Bir
authors.forename: Oishimaya
authors.initials: O
authors.lastname: Sen
authors.forename: Shruti
authors.initials: S
authors.lastname: Anand
authors.forename: Vineet Kumar
authors.initials: VK
authors.lastname: Khemka
authors.forename: Priyanjalee
authors.initials: P
authors.lastname: Banerjee
authors.forename: Roberto
authors.initials: R
authors.lastname: Cappai
authors.forename: Arghyadip
authors.initials: A
authors.lastname: Sahoo
authors.forename: Sasanka
authors.initials: S
authors.lastname: Chakrabarti
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore; D010300:Parkinson Disease / Q000378:metabolism*; D017208:Rats, Wistar; D051844:alpha-Synuclein / Q000187:drug effects / Q000378:metabolism*
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C497604:SNCA protein, human; C497606:Snca protein, rat; D051844:alpha-Synuclein; C067713:lactacystin; D000111:Acetylcysteine
keywords: Parkinson's disease; cyclophilin D; lactacystin; mitochondrial dysfunction; permeability transition pore; α-synuclein