Inducible over-expression of wild type alpha-synuclein in human neuronal cells leads to caspase-dependent non-apoptotic death.
Alpha-synuclein (ASYN) is central in Parkinson's disease pathogenesis. Converging pieces of evidence suggest that the levels of ASYN expression play a critical role in both familial and sporadic Parkinson's disease. To elucidate the mechanism underlying wild type (WT) ASYN-mediated neurotoxicity, we have generated a novel Tet-Off SHSY-5Y cell line, conditionally expressing WT ASYN. Induction of human WT ASYN in retinoic acid-differentiated SHSY-5Y cells leads to accumulation of soluble ASYN oligomers, in the absence of inclusions, and to gradual cellular degeneration. Morphologically, the death observed is non-apoptotic. Caspases other than caspase 3, including caspase 9, are activated and caspase inhibition diminishes death by acting at a point upstream of cytochrome c release. Application of Scyllo-inositol, an oligomer-stabilizing compound, prevents neuronal death in this model. These findings are consistent with a model in which oligomeric ASYN triggers the initial activation of the apoptotic pathway, which is however blocked downstream of the mitochondrial checkpoint, thus leading to a death combining in a unique fashion both apoptotic and non-apoptotic features. This novel inducible cell model system may prove valuable in the deciphering of WT ASYN-induced pathogenic effects and in the assessment and screening of potential therapeutic strategies.
Vekrellis
Kostas
K
Division of Basic Neurosciences, Biomedical Research Foundation of the Academy of Athens, Soranou Efesiou, Athens, Greece. vekrellis@bioacademy.gr
Xilouri
Maria
M
Emmanouilidou
Evangelia
E
Stefanis
Leonidas
L
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D020169:Caspases / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D007294:Inositol / Q000494:pharmacology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects; D009447:Neuroblastoma / Q000648:ultrastructure; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection / Q000379:methods; D014212:Tretinoin / Q000494:pharmacology; D051844:alpha-Synuclein / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D004791:Enzyme Inhibitors; D051844:alpha-Synuclein; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C009217:scyllitol; D007294:Inositol; D014212:Tretinoin; D045304:Cytochromes c; D020169:Caspases; D019311:Staurosporine