Regulation of endosomal membrane traffic by a Gadkin/AP-1/kinesin KIF5 complex

Proc Natl Acad Sci U S A. 2009 Sep 8;106(36):15344-9. doi: 10.1073/pnas.0904268106. Epub 2009 Aug 21.

Abstract

Endosomes and endosomal vesicles (EVs) rapidly move along cytoskeletal filaments allowing them to exchange proteins and lipids between different endosomal compartments, lysosomes, the trans-Golgi network (TGN), and the plasma membrane. The precise mechanisms that connect membrane traffic between the TGN and perinuclear endosomal compartments with motor-protein driven transport have largely remained elusive. Here we show that Gadkin (also termed gamma-BAR), a peripheral membrane protein localized to the TGN and to TGN-derived EVs, directly associates with the clathrin adaptor AP-1 and with the motor protein kinesin KIF5, thereby potentially regulating EV dynamics. Gadkin overexpression induced the dispersion of transferrin (Tf)- and Rab4-positive EVs to the cell periphery, whereas KIF5B-depleted cells displayed a perinuclear concentration. Functional experiments suggest that the role of Gadkin as a regulator of endosomal membrane traffic critically depends on complex formation with both AP-1 and KIF5. Our data thus provide a direct molecular link between TGN-derived EVs and the microtubule-based cytoskeleton.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport, Active / physiology
  • COS Cells
  • Chlorocebus aethiops
  • Chromatography, Affinity
  • Endosomes / metabolism*
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Kinesins / metabolism*
  • Membrane Proteins / metabolism*
  • Microscopy, Fluorescence
  • Multiprotein Complexes / metabolism*
  • Transcription Factor AP-1 / metabolism*

Substances

  • AP1AR protein, human
  • KIF5A protein, human
  • Membrane Proteins
  • Multiprotein Complexes
  • Transcription Factor AP-1
  • Kinesins