The Vps35 <scp>D620N</scp> Mutation Linked to Parkinson's Disease Disrupts the Cargo Sorting Function of Retromer

<jats:p>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 (<jats:styled-content style="fixed-case">D620N</jats:styled-content>) was linked to the manifestation of Parkinson's disease (<jats:styled-content style="fixed-case">PD</jats:styled-content>). Here, we investigated details underlying the molecular mechanism by which the <jats:styled-content style="fixed-case">D620N</jats:styled-content> 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 <jats:styled-content style="fixed-case">PD</jats:styled-content>‐linked Vps35 <jats:styled-content style="fixed-case">D620N</jats:styled-content> 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 <jats:styled-content style="fixed-case">PD</jats:styled-content> patient. Vps35 <jats:styled-content style="fixed-case">D620N</jats:styled-content> is correctly folded and binds Vps29 and <jats:styled-content style="fixed-case">Vps26A</jats:styled-content> with the same affinity as wild‐type Vps35. While <jats:styled-content style="fixed-case">PD</jats:styled-content>‐linked point mutant Vps35 <jats:styled-content style="fixed-case">D620N</jats:styled-content> interacts with the cation‐independent mannose‐6‐phosphate receptor (<jats:styled-content style="fixed-case">CI‐M6PR</jats:styled-content>), a known retromer cargo, we find that its expression disrupts the trafficking of cathepsin D, a <jats:styled-content style="fixed-case">CI‐M6PR</jats:styled-content> ligand and protease responsible for degradation of α‐synuclein, a causative agent of PD. In summary, we find that the expression of Vps35 <jats:styled-content style="fixed-case">D620N</jats:styled-content> leads to endosomal alterations and trafficking defects that may partly explain its action in <jats:styled-content style="fixed-case">PD</jats:styled-content>.<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/tra12136-gra-0001.gif" xlink:title="image" /></jats:p>