Nanoscopic insights into seeding mechanisms and toxicity of α-synuclein species in neurons.

Change log
Pinotsi, Dorothea 
Michel, Claire H 
Buell, Alexander K 
Laine, Romain F 
Mahou, Pierre 

New strategies for visualizing self-assembly processes at the nanoscale give deep insights into the molecular origins of disease. An example is the self-assembly of misfolded proteins into amyloid fibrils, which is related to a range of neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases. Here, we probe the links between the mechanism of α-synuclein (AS) aggregation and its associated toxicity by using optical nanoscopy directly in a neuronal cell culture model of Parkinson's disease. Using superresolution microscopy, we show that protein fibrils are taken up by neuronal cells and act as prion-like seeds for elongation reactions that both consume endogenous AS and suppress its de novo aggregation. When AS is internalized in its monomeric form, however, it nucleates and triggers the aggregation of endogenous AS, leading to apoptosis, although there are no detectable cross-reactions between externally added and endogenous protein species. Monomer-induced apoptosis can be reduced by pretreatment with seed fibrils, suggesting that partial consumption of the externally added or excess soluble AS can be significantly neuroprotective.

neurodegenerative disease, optical nanoscopy, prion-like behavior, seeding, α-synuclein, Alzheimer Disease, Amyloid, Apoptosis, Cells, Cultured, Humans, Neurons, Parkinson Disease, Protein Aggregation, Pathological, Protein Transport, Proteostasis Deficiencies, alpha-Synuclein
Journal Title
Proc Natl Acad Sci U S A
Conference Name
Journal ISSN
Volume Title
Proceedings of the National Academy of Sciences
Engineering and Physical Sciences Research Council (EP/H018301/1)
Medical Research Council (G0902243)
Medical Research Council (MR/K02292X/1)
Medical Research Council (MR/K015850/1)
Medical Research Council (MR/N012453/1)
Medical Research Council (MC_G1000734)
Wellcome Trust (089703/Z/09/Z)
We thank Dr Q. Jeng and Dr A. Stephens for technical assistance and Dr J. Skepper for TEM imaging. This work was funded by grants from the U.K. Medical Research Council (MR/K015850/1 and MR/K02292X/1), Alzheimer’s Research UK (ARUK-EG2012A-1), U.K. Engineering and Physical Sciences Research Council (EPSRC) (EP/H018301/1) and the Wellcome Trust (089703/Z/09/Z). D.P. wishes to acknowledge support from the Swiss National Science Foundation and the Wellcome Trust through personal fellowships. A.K.B thanks Magdalene College, Cambridge and the Leverhulme Trust for support.