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  • The Vps35 D620N Mutation Li...
    Follett, Jordan; Norwood, Suzanne J.; Hamilton, Nicholas A.; Mohan, Megha; Kovtun, Oleksiy; Tay, Stephanie; Zhe, Yang; Wood, Stephen A.; Mellick, George D.; Silburn, Peter A.; Collins, Brett M.; Bugarcic, Andrea; Teasdale, Rohan D.

    Traffic (Copenhagen, Denmark), February 2014, Volume: 15, Issue: 2
    Journal Article

    A genetic mutation in the Vps35 subunit of retromer has recently been linked to late onset Parkinson's disease. We observed that the distribution and maturation of Vps35 D620N positive endosomes are altered. While Vps35 D620N containing retromer still binds CI‐M6PR, its trafficking is perturbed as shown by secretion of its ligand cathepsin D. As cathepsin D is involved in processing of α‐synuclein, a well‐established causative agent of Parkinson's disease, its altered trafficking may therefore represent the underlying cause of disease. The retromer is a trimeric cargo‐recognition protein complex composed of Vps26, Vps29 and Vps35 associated with protein trafficking within endosomes. Recently, a pathogenic point mutation within the Vps35 subunit (D620N) was linked to the manifestation of Parkinson's disease (PD). Here, we investigated details underlying the molecular mechanism by which the D620N mutation in Vps35 modulates retromer function, including examination of retromer's subcellular localization and its capacity to sort cargo. We show that expression of the PD‐linked Vps35 D620N mutant redistributes retromer‐positive endosomes to a perinuclear subcellular localization and that these endosomes are enlarged in both model cell lines and fibroblasts isolated from a PD patient. Vps35 D620N is correctly folded and binds Vps29 and Vps26A with the same affinity as wild‐type Vps35. While PD‐linked point mutant Vps35 D620N interacts with the cation‐independent mannose‐6‐phosphate receptor (CI‐M6PR), a known retromer cargo, we find that its expression disrupts the trafficking of cathepsin D, a CI‐M6PR ligand and protease responsible for degradation of α‐synuclein, a causative agent of PD. In summary, we find that the expression of Vps35 D620N leads to endosomal alterations and trafficking defects that may partly explain its action in PD.