RAB-10-GTPase-mediated regulation of endosomal phosphatidylinositol-4,5-bisphosphate

Proc Natl Acad Sci U S A. 2012 Aug 28;109(35):E2306-15. doi: 10.1073/pnas.1205278109. Epub 2012 Aug 6.


Caenorhabditis elegans RAB-10 and mammalian Rab10 are key regulators of endocytic recycling, especially in the basolateral recycling pathways of polarized epithelial cells. To understand better how RAB-10 contributes to recycling endosome function, we sought to identify RAB-10 effectors. One RAB-10-binding partner that we identified, CNT-1, is the only C. elegans homolog of the mammalian Arf6 GTPase-activating proteins ACAP1 and ACAP2. Arf6 is known to regulate endosome-to-plasma membrane transport, in part through activation of type I phophatidylinositol-4-phosphate 5 kinase. Here we show that CNT-1 binds to RAB-10 through its C-terminal ankyrin repeats and colocalizes with RAB-10 and ARF-6 on recycling endosomes in vivo. Furthermore, we find that RAB-10 is required for the recruitment of CNT-1 to endosomal membranes in the intestinal epithelium. Consistent with negative regulation of ARF-6 by RAB-10 and CNT-1, we found overaccumulation of endosomal phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] in cnt-1 and rab-10 mutants and reduced endosomal PI(4,5)P2 levels in arf-6 mutants. These mutants produced similar effects on endosomal recruitment of the PI(4,5)P2-dependent membrane-bending proteins RME-1/Ehd and SDPN-1/Syndapin/Pacsin and resulted in endosomal trapping of specific recycling cargo. Our studies identify a RAB-10-to-ARF-6 regulatory loop required to regulate endosomal PI(4,5)P2, a key phosphoinositide in membrane traffic.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Caenorhabditis elegans / enzymology*
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans Proteins / chemistry
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Membrane / metabolism
  • Clathrin / metabolism
  • Endocytosis / physiology
  • Endosomes / enzymology*
  • GTP Phosphohydrolases / chemistry
  • GTP Phosphohydrolases / metabolism*
  • GTPase-Activating Proteins / chemistry
  • GTPase-Activating Proteins / genetics
  • GTPase-Activating Proteins / metabolism*
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Protein Structure, Tertiary
  • Protein Transport / physiology
  • Two-Hybrid System Techniques
  • rab GTP-Binding Proteins / chemistry
  • rab GTP-Binding Proteins / metabolism*


  • CNT-1 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Clathrin
  • GTPase-Activating Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • GTP Phosphohydrolases
  • RAB-10 protein, C elegans
  • rab GTP-Binding Proteins