RT Journal Article
SR Electronic
T1 Rab27b regulates the release, autophagic clearance, and toxicity of alpha-synuclein
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.03.09.984096
DO 10.1101/2020.03.09.984096
A1 Rachel Underwood
A1 Bing Wang
A1 Christine Carico
A1 Robert H. Whitaker
A1 William J. Placzek
A1 Talene Yacoubian
YR 2020
UL http://biorxiv.org/content/early/2020/03/09/2020.03.09.984096.abstract
AB Alpha synuclein (αsyn) is the primary component of proteinaceous aggregates termed Lewy Bodies that pathologically define synucleinopathies including Parkinson’s disease (PD) and Dementia with Lewy Bodies (DLB). αSyn is hypothesized to spread through the brain in a prion-like fashion by misfolded protein forming a template for aggregation of endogenous αsyn. The release and uptake of αsyn from cell to cell are considered important processes for this prion-like spread. Rab27b is one of several GTPases essential to the endosomal-lysosomal pathway and is implicated in protein secretion and clearance but has yet to be characterized in its role in αsyn spread. In this study, we used a paracrine αsyn in vitro model to test the impact of Rab27b on αsyn release, clearance, and toxicity. shRNA-mediated knockdown (KD) of Rab27b increased αsyn-mediated paracrine toxicity. While Rab27b reduced αsyn release primarily through non-exosomal pathways, the αsyn released under KD conditions was of higher molecular weight species by size exclusion chromatography. Rab27b KD increased intracellular insoluble αsyn levels and led to an accumulation of endogenous LC3 positive puncta. Rab27b KD also decreased LC3 turnover with chloroquine treatment, indicating a defect in autophagic flux. Rab27b protein levels were increased in postmortem human brain lysates from PD and DLB subjects compared to healthy controls. These data indicate a role for Rab27b in the release, clearance, and toxicity of αsyn and ultimately in the pathogenesis of synucleinopathies.αsynalpha-synucleinCMconditioned mediaDLBDementia with Lewy BodiesdoxydoxycyclineEVempty vectorisyndoxycycline-inducible alpha-synuclein cell lineKDknockdownKOknockoutPDParkinson’s disease