Retromer Binding to FAM21 and the WASH Complex Is Perturbed by the Parkinson Disease-Linked VPS35(D620N) Mutation

Abstract

SummaryRetromer is a protein assembly that plays a central role in orchestrating export of transmembrane-spanning cargo proteins from endosomes into retrieval pathways destined for the Golgi apparatus and the plasma membrane [1]. Recently, a specific mutation in the retromer component VPS35, VPS35(D620N), has linked retromer dysfunction to familial autosomal dominant and sporadic Parkinson disease [2, 3]. However, the effect of this mutation on retromer function remains poorly characterized. Here we established that in cells expressing VPS35(D620N) there is a perturbation in endosome-to-TGN transport but not endosome-to-plasma membrane recycling, which we confirm in patient cells harboring the VPS35(D620N) mutation. Through comparative stable isotope labeling by amino acids in cell culture (SILAC)-based analysis of wild-type VPS35 versus the VPS35(D620N) mutant interactomes, we establish that the major defect of the D620N mutation lies in the association to the actin-nucleating Wiskott-Aldrich syndrome and SCAR homolog (WASH) complex. Moreover, using isothermal calorimetry, we establish that the primary defect of the VPS35(D620N) mutant is a 2.2 ± 0.5-fold decrease in affinity for the WASH complex component FAM21. These data define the primary molecular defect in retromer assembly that arises from the VPS35(D620N) mutation and, by revealing functional effects on retromer-mediated endosome-to-TGN transport, provide new insight into retromer deregulation in Parkinson disease.

A defect in the retromer accessory protein, SNX27, manifests by infantile myoclonic epilepsy and neurodegeneration

“…Mutations in VPS35, VPS26A and the retromer accessory protein DNAJC13 [43][44][45][46] have been associated with late-onset autosomal dominant Parkinson's disease (PD) [47][48][49][50]. Indeed, the PD-linked VPS35(p.D620N) mutation displays a reduced ability to associate with the actin polymerizing WASH (Wiskott-Aldrich syndrome protein and SCAR Homology) complex [51][52][53] which leads to altered endosome-to-Golgi transport and autophagosome formation [54,44,55,56]. Perturbed function of the WASH complex is also implicated in hereditary spastic paraplegia [57].…”

Cellular functions of WASP family proteins at a glance

“…WASH is recruited to retromer-positive endosomal subdomains via the interaction of the extended C-terminal tail of FAM21 with the retromer subunit VPS35 (Harbour et al, 2012;Jia et al, 2012). Interestingly, a mutation in VPS35 (D620N) (Vilariño-Güell et al, 2011;Zimprich et al, 2011) that is associated with earlyonset Parkinson's disease has been shown to diminish the interaction of the SHRC with VPS35 and impair vesicular trafficking from the late endosome (Follett et al, 2013;McGough et al, 2014;Zavodszky et al, 2014). Studies in Drosophila have recently shown important roles for WASH in regulating integrin receptor trafficking and lysosome acidification (Nagel et al, 2017).…”

Membrane Trafficking Illuminates a Path to Parkinson’s Disease

“…Structurally, the retromer is comprised of two distinct subcomplexes: a cargo-recognition VPS26-VPS29-VPS35 heterotrimer and a membrane-targeting dimer of the sorting nexin (SNX1 and/or SNX2). Cell biological studies have shown that the PD-linked D620N VPS35 mutant associates poorly with the WASH (Wiskott-Aldrich syndrome protein and SCAR homolog) complex and impairs WASH recruitment to the endosomes (McGough et al 2014). Interestingly, autophagy is impaired in cells expressing the PD-mutant VPS35 or lacking WASH, which could be explained, at least in part, by the abnormal trafficking of ATG9A, a transmembrane protein that is required for autophagosome biogenesis (Zavodszky et al 2014).…”