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J Cell Sci. 2014 Nov 15;127(Pt 22):4940-53. doi: 10.1242/jcs.156299. Epub 2014 Oct 2.

Identification of molecular heterogeneity in SNX27-retromer-mediated endosome-to-plasma-membrane recycling.

Author information

1
The Henry Wellcome Integrated Signaling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK.
2
Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan.
3
Proteomics Facility, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK.
4
The Henry Wellcome Integrated Signaling Laboratories, School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK Pete.Cullen@bristol.ac.uk.

Abstract

Retromer is a protein assembly that orchestrates the sorting of transmembrane cargo proteins into endosome-to-Golgi and endosome-to-plasma-membrane transport pathways. Here, we have employed quantitative proteomics to define the interactome of human VPS35, the core retromer component. This has identified a number of new interacting proteins, including ankyrin-repeat domain 50 (ANKRD50), seriologically defined colon cancer antigen 3 (SDCCAG3) and VPS9-ankyrin-repeat protein (VARP, also known as ANKRD27). Depletion of these proteins resulted in trafficking defects of retromer-dependent cargo, but differential and cargo-specific effects suggested a surprising degree of functional heterogeneity in retromer-mediated endosome-to-plasma-membrane sorting. Extending this, suppression of the retromer-associated WASH complex did not uniformly affect retromer cargo, thereby confirming cargo-specific functions for retromer-interacting proteins. Further analysis of the retromer-VARP interaction identified a role for retromer in endosome-to-melanosome transport. Suppression of VPS35 led to mistrafficking of the melanogenic enzymes, tyrosinase and tryrosine-related protein 1 (Tyrp1), establishing that retromer acts in concert with VARP in this trafficking pathway. Overall, these data reveal hidden complexities in retromer-mediated sorting and open up new directions in our molecular understanding of this essential sorting complex.

KEYWORDS:

Retromer; SNX27; Sorting nexin; VARP; VPS35

PMID:
25278552
PMCID:
PMC4231307
DOI:
10.1242/jcs.156299
[Indexed for MEDLINE]
Free PMC Article

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