alpha-Synuclein interacts with the switch region of Rab8a in a Ser129 phosphorylation-dependent manner

Alpha-synuclein (alpha S) misfolding is associated with Parkinson's disease (PD) but little is known about the mechanisms underlying alpha S toxicity. Increasing evidence suggests that defects in membrane transport play an important role in neuronal dysfunction. Here we demonstrate that the GTPase Rab8a interacts with alpha S in rodent brain. NMR spectroscopy reveals that the C-terminus of alpha S binds to the functionally important switch region as well as the C-terminal tail of Rab8a. In line with a direct Rab8a/alpha S interaction, Rab8a enhanced alpha S aggregation and reduced alpha S-induced cellular toxicity. In addition, Rab8 - the Drosophila ortholog of Rab8a - ameliorated alpha S-oligomer specific locomotor impairment and neuron loss in fruit flies. In support of the pathogenic relevance of the alpha S-Rab8a interaction, phosphorylation of alpha S at S129 enhanced binding to Rab8a, increased formation of insoluble alpha S aggregates and reduced cellular toxicity. Our study provides novel mechanistic insights into the interplay of the GTPase Rab8a and alpha S cytotoxicity, and underscores the therapeutic potential of targeting this interaction. (C) 2014 Elsevier Inc. All rights reserved.