Cytotoxicity, extracellular α-syn uptake and recruitment of endogenous α-syn in SH-SY5Y cells. (A) Cells were treated with 5 μg/mL α-syn oligomers, short, and long fibrils for 24 hours. Results are mean ± st. dev. of three independent experiments performed in six replicas. (B) Internalization of FLAG-α-syn amyloids into neuroblastoma cells SH-SY5Y. α-Syn deposition (green) was detected by anti-human α-syn antibody. Immunofluorescence was performed on cells exposed to FLAG-α-syn amyloids (oligomers, short amyloid fibrils and long fibrils) for 7 days. Bar, 11.9 μm. (C) Formation of endogenous α-syn deposits induced by extracellular α-syn short amyloid fibrils. Cells were treated for 7 days. Western blot analysis was performed using the α-syn (C-20)-R antibody, which recognizes endogenous human α-syn in SH-SY5Y cells. The nuclei (blue) were stained with DAPI. Scale bars, 11.9 μm.