Objective: Aim of the study is to understand the physical and functional relationships between the PD-associated protein α-synuclein and some of the Soluble N-ethylmaleimide-sensitive-factor Attachment proteins Receptor, regulators of vesicular and membrane fusion events.

Background: Parkinson’s Disease (PD) is a neurodegenerative disorder characterized by defects in membrane trafficking. SNCA, encoding α-synuclein (α-syn), is a major genetic determinants of PD pathogenesis involved in membrane trafficking. α-syn has recently emerged as regulator of SNARE (Soluble N-ethylmaleimide-sensitive-factor Attachment protein Receptor)-dependent vesicle fusion. Recently the vesicular SNARE protein VAMP4 emerged as novel PD-risk factor and VAMP7 as a mediator of ER-phagy secretion. Here we proposed to investigate the potential functional interactions between α-syn and VAMPs 4 and 7 as well as the effect of VAMPs on α-syn release in extracellular space.

Method: The co-localization between α-syn and VAMPs was analyzed by immunocytochemistry and Proximity Ligation Assay. The released α-syn exocytosis was measured at different time points upon α-syn over-expression. Extracellular vesicles were isolated from cell culture media in VAMPs (2, 4, 7) KO cellular model stably overexpressing α-syn. Pharmacological treatment with MG132 was performed in the VAMPs KO cells in order to analyze the effect of proteasome inhibition on α-syn exocytosis VAMPs-dependent.

Results: We present results of PLA and co-localization showing a potential interaction between α-syn and VAMPs 2 and 7. Inhibition of proteasome activity induces an increase of intracellular α-syn protein levels as well as an increased α-syn release into extracellular vesicles after 24h. We observed a reduced α-syn release in exosomes isolated from PC12 KO for VAMP4 and VAMP7 compared to WT PC12 cells.

Conclusion: α-syn and VAMPs are both involved in vesicular and membrane trafficking and our results suggest an involvement of VAMPs in vesicles release and α-syn exocytosis. In our perspectives, we will evaluate the effect of VAMPs on the α-syn aggregation and exocytosis in order to evaluate if the α-syn homeostasis could be modulated by SNARE proteins.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/%ce%b1-synuclein-and-deficits-of-membrane-trafficking-in-parkinsons-disease/