title: Aggregation and neurotoxicity of recombinant α-synuclein aggregates initiated by dimerization.
abstract: BACKGROUND
  Aggregation of the α-Synuclein (α-Syn) protein, amyloid fibril formation and progressive neurodegeneration are the neuropathological hallmarks of Parkinson's Disease (PD). However, a detailed mechanism of α-Syn aggregation/fibrillogenesis and the exact nature of toxic oligomeric species produced during amyloid formation process are still unknown.
  
  
  RESULTS
  In this study, the rates of α-Syn aggregation were compared for the recombinant wild-type (WT) α-Syn and a structurally relevant chimeric homologous protein containing an inducible Fv dimerizing domain (α-SynFv), capable to form dimers in the presence of a divalent ligand (AP20187). In the presence of AP20187, we report a rapid random coil into β-sheet conformational transformation of α-SynFv within 24 h, whereas WT α-Syn showed 24 h delay to achieve β-sheet structure after 48 h. Fluorescence ANS and ThT binding experiments demonstrate an accelerated oligomer/amyloid formation of dimerized α-SynFv, compared to the slower oligomerization and amyloidogenesis of WT α-Syn or α-SynFv without dimerizer AP20187. Both α-SynFv and α-Syn pre-fibrillar aggregates internalized cells and induced neurotoxicity when injected into the hippocampus of wild-type mice. These recombinant toxic aggregates further converted into non-toxic amyloids which were successfully amplified by protein misfolding cyclic amplification method, providing the first evidence for the in vitro propagation of synthetic α-Syn aggregates.
  
  
  CONCLUSIONS
  Together, we show that dimerization is important for α-Syn conformational transition and aggregation. In addition, α-Syn dimerization can accelerate the formation of neurotoxic aggregates and amyloid fibrils which can be amplified in vitro. A detailed characterization of the mechanism of α-Syn aggregation/amyloidogenesis and toxicity is crucial to comprehend Parkinson's disease pathology at the molecular level.
authors: Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Canada.
authors: Alireza
authors: A
authors: Roostaee
authors: Simon
authors: S
authors: Beaudoin
authors: Antanas
authors: A
authors: Staskevicius
authors: Xavier
authors: X
authors: Roucou
mesh_terms: D000818:Animals; D006624:Hippocampus / Q000473:pathology*; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010300:Parkinson Disease / Q000473:pathology; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000633:toxicity; D051844:alpha-Synuclein / Q000737:chemistry* / Q000633:toxicity*
chemical_list: D011994:Recombinant Proteins; D051844:alpha-Synuclein