Identification of a novel interaction between α‐synuclein and VMAT2

Abstract

Several familial forms of Parkinson disease are linked to mutations in α‐synuclein (α‐syn), a major component of Lewy bodies. One proposed role for α‐syn in dopaminergic neurons is the maintenance of dopamine (DA) homeostasis. We have identified an interaction with α‐syn and the vesicular monoamine transporter 2 (VMAT2). VMAT2 sequesters cytosolic DA into vesicles for release at synaptic terminals. Here, we show an interaction between α‐syn and the C‐terminus of VMAT2 by yeast two‐hybrid assay. This interaction is confirmed by coimmunoprecipitation of α‐syn with VMAT2 in SHSY5Y cells. Immunofluorescence confocal microscopy shows both perinuclear and punctate neuritic‐like colocalization of VMAT2 and α‐syn in heterologously coexpressing SHSY5Y cells and natively‐expressing primary mouse nigral neurons. This staining is consistent with vesicle colocalization and a perinuclear compartment such as golgi or endoplasmic reticulum. Finally, coexpression of α‐syn increases tetrabenazine sensitive‐VMAT2 sequestration of 3H‐DA in SHSY5Y cell lysates. This increase in transporter activity is reflective of a 2‐fold increase in Vmax. These data suggest that one function of α‐syn may be to maintain proper storage of DA via regulation of VMAT2. Since the storage of DA also protects DA from oxidation, α‐syn may maintain high VMAT2 activity to protect dopaminergic neurons from cell death. Supported by U54ES‐012068.