Internalization of α-synuclein oligomers into SH-SY5Y cells

• Published in: Biophysical journal Vol. 120; no. 5; pp. 877 - 885
• Main Authors: Shearer, Lindsay J., Petersen, Nils O., Woodside, Michael T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02.03.2021; The Biophysical Society
• Subjects: alpha-Synuclein - metabolism; Biological Transport; Endocytosis; Humans; Lysosomes - metabolism
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1016/j.bpj.2020.12.031

Aggregates of misfolded α-synuclein are a distinctive feature of Parkinson’s disease. Small oligomers of α-synuclein are thought to be an important neurotoxic agent, and α-synuclein aggregates exhibit prion-like behavior, propagating misfolding between cells. α-Synuclein is internalized by both passive diffusion and active uptake mechanisms, but how uptake varies with the size of the oligomer is less clear. We explored how α-synuclein internalization into live SH-SY5Y cells varied with oligomer size by comparing the uptake of fluorescently labeled monomers to that of engineered tandem dimers and tetramers. We found that these α-synuclein constructs were internalized primarily through endocytosis. Oligomer size had little effect on their internalization pathway, whether they were added individually or together. Measurements of co-localization of the α-synuclein constructs with fluorescent markers for early endosomes and lysosomes showed that most of the α-synuclein entered endocytic compartments, in which they were probably degraded. Treatment of the cells with the Pitstop inhibitor suggested that most of the oligomers were internalized by the clathrin-mediated pathway.