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

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.

• Authors: Ian J McGough, Florian Steinberg, Matthew Gallon, Ayaka Yatsu, Norihiko Ohbayashi, Kate J Heesom, Mitsunori Fukuda, Peter J Cullen
• Journal: Journal of cell science (J Cell Sci) Vol. 127 Issue Pt 22 Pg. 4940-53 (Nov 15 2014) ISSN: 1477-9137 [Electronic] England
• PMID: 25278552 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014. Published by The Company of Biologists Ltd.

Chemical References

• SNX27 protein, human
• Sorting Nexins
• Transferrin
• VPS35 protein, human
• Vesicular Transport Proteins
• rab GTP-Binding Proteins

Topics

• Cell Membrane (metabolism)
• Endosomes (metabolism)
• HeLa Cells
• Humans
• Protein Transport
• Sorting Nexins (metabolism)
• Transfection
• Transferrin (metabolism)
• Vesicular Transport Proteins (metabolism)
• rab GTP-Binding Proteins (metabolism)