Membrane recruitment of the cargo-selective retromer subcomplex is catalysed by the small GTPase Rab7 and inhibited by the Rab-GAP TBC1D5

J Cell Sci. 2009 Jul 15;122(Pt 14):2371-82. doi: 10.1242/jcs.048686. Epub 2009 Jun 16.

Abstract

Retromer is a membrane-associated heteropentameric coat complex that functions in the endosome-to-Golgi retrieval of the cation-independent mannose-6-phosphate receptor, the Wntless protein and other membrane proteins of physiological significance. Retromer comprises two functional subcomplexes: the cargo-selective subcomplex is a trimer of the VPS35, VPS29, VPS26 proteins, whereas the sorting nexin proteins, Snx1 and Snx2 function to tubulate the endosomal membrane. Unlike the sorting nexins, which contain PtdIns3P-binding PX domains, the cargo-selective VPS35/29/26 complex has no lipid-binding domains and its recruitment to the endosomal membrane remains mechanistically uncharacterised. In this study we show that the VPS35/29/26 complex interacts with the small GTPase Rab7 and requires Rab7 for its recruitment to the endosome. We show that the Rab7K157N mutant that causes the peripheral neuropathy, Charcot-Marie-Tooth disease, does not interact with the VPS35/29/26 complex, resulting in a weakened association with the membrane. We have also identified a novel retromer-interacting protein, TBC1D5, which is a member of the Rab GAP family of proteins that negatively regulates VPS35/29/26 recruitment and causes Rab7 to dissociate from the membrane. We therefore propose that recruitment of the cargo-selective VPS35/29/26 complex is catalysed by Rab7 and inhibited by the Rab-GAP protein, TBC1D5.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COP-Coated Vesicles / metabolism*
  • Charcot-Marie-Tooth Disease / genetics
  • Charcot-Marie-Tooth Disease / metabolism
  • Cytoplasm / metabolism
  • Endosomes / metabolism*
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism*
  • Golgi Apparatus / metabolism
  • HeLa Cells
  • Humans
  • Intracellular Membranes / metabolism*
  • Mutation
  • Protein Transport
  • RNA Interference
  • Recombinant Fusion Proteins / metabolism
  • Transfection
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism*
  • rab7 GTP-Binding Proteins

Substances

  • GTPase-Activating Proteins
  • Recombinant Fusion Proteins
  • TBC1D5 protein, human
  • VPS26A protein, human
  • VPS29 protein, human
  • VPS35 protein, human
  • Vesicular Transport Proteins
  • rab7 GTP-Binding Proteins
  • rab7 GTP-binding proteins, human
  • rab GTP-Binding Proteins