Cargo-selective SNX-BAR proteins mediate retromer trimer independent retrograde transport

J Cell Biol. 2017 Nov 6;216(11):3677-3693. doi: 10.1083/jcb.201702137. Epub 2017 Sep 21.

Abstract

The retromer complex, which recycles the cation-independent mannose 6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network (TGN), is thought to consist of a cargo-selective VPS26-VPS29-VPS35 trimer and a membrane-deforming subunit of sorting nexin (SNX)-Bin, Amphyphysin, and Rvs (BAR; SNX-BAR) proteins. In this study, we demonstrate that heterodimers of the SNX-BAR proteins, SNX1, SNX2, SNX5, and SNX6, are the cargo-selective elements that mediate the retrograde transport of CI-MPR from endosomes to the TGN independently of the core retromer trimer. Using quantitative proteomics, we also identify the IGF1R, among more potential cargo, as another SNX5 and SNX6 binding receptor that recycles through SNX-BAR heterodimers, but not via the retromer trimer, in a ligand- and activation-dependent manner. Overall, our data redefine the mechanics of retromer-based sorting and call into question whether retromer indeed functions as a complex of SNX-BAR proteins and the VPS26-VPS29-VPS35 trimer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CRISPR-Cas Systems
  • Endosomes / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • MCF-7 Cells
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Transport
  • RNA Interference
  • Receptor, IGF Type 2 / chemistry
  • Receptor, IGF Type 2 / genetics
  • Receptor, IGF Type 2 / metabolism*
  • Sorting Nexins / chemistry
  • Sorting Nexins / genetics
  • Sorting Nexins / metabolism*
  • Time Factors
  • Transfection
  • Vesicular Transport Proteins / chemistry
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*
  • trans-Golgi Network / metabolism

Substances

  • Nerve Tissue Proteins
  • Receptor, IGF Type 2
  • SNX1 protein, human
  • SNX2 protein, human
  • SNX5 protein, human
  • SNX6 protein, human
  • Sorting Nexins
  • VPS26A protein, human
  • VPS29 protein, human
  • VPS35 protein, human
  • Vesicular Transport Proteins
  • cation-dependent mannose-6-phosphate receptor
  • amphiphysin