A novel link between the conformations, exposure of specific epitopes, and subcellular localization of alpha-synuclein

Abstract

Background: Genetic studies and the abundance of alpha-synuclein (alpha-Syn) in presynaptic terminals suggest that alpha-Syn plays a critical role in maintaining synaptic vesicle pools. However, there are still few experimental tools for elucidating its physiological roles. Methods: Unexpectedly, we detected various cellular distribution patterns of endogenous alpha-Syn by immunofluorescence assays (IFAs). To provide new molecular insights into alpha-Syn research, we identified associations between epitopes, conformations, and subcellular localization of alpha-Syn and categorized them. Results: The alpha-Syn exposing Y125 was found to coexist with F-actin at the edge of the cells, including the plasma membrane. alpha-Syn conformations exposing P128 or both F94 and K97 were partly localized to the mitochondria. These results indicate that various conformations of alpha-Syn are associated with specific subcellular localizations. Intriguingly, we demonstrate for the first time that the phosphorylated alpha-Syn at Ser129, also known as a Parkinson's disease (PD)-causing form, is targeted to the mitochondria. Conclusions: Our study showed that different subcellular distribution patterns of alpha-Syn reflect the existence of various alpha-Syn conformations under normal conditions. General significance: This study provides novel clues for deciphering the physiological function of alpha-Syn in connection with subcellular localization. Dissecting the specific alpha-Syn conformations may lead to useful strategies in PD therapy and diagnosis. (C) 2015 Elsevier B.V. All rights reserved.