Huntingtin coordinates the dynein-mediated dynamic positioning of endosomes and lysosomes

Mol Biol Cell. 2011 Feb 15;22(4):478-92. doi: 10.1091/mbc.E10-03-0233. Epub 2010 Dec 17.

Abstract

Huntingtin (Htt) is a membrane-associated scaffolding protein that interacts with microtubule motors as well as actin-associated adaptor molecules. We examined a role for Htt in the dynein-mediated intracellular trafficking of endosomes and lysosomes. In HeLa cells depleted of either Htt or dynein, early, recycling, and late endosomes (LE)/lysosomes all become dispersed. Despite altered organelle localization, kinetic assays indicate only minor defects in intracellular trafficking. Expression of full-length Htt is required to restore organelle localization in Htt-depleted cells, supporting a role for Htt as a scaffold that promotes functional interactions along its length. In dynein-depleted cells, LE/lysosomes accumulate in tight patches near the cortex, apparently enmeshed by cortactin-positive actin filaments; Latrunculin B-treatment disperses these patches. Peripheral LE/lysosomes in dynein-depleted cells no longer colocalize with microtubules. Htt may be required for this off-loading, as the loss of microtubule association is not seen in Htt-depleted cells or in cells depleted of both dynein and Htt. Inhibition of kinesin-1 relocalizes peripheral LE/lysosomes induced by Htt depletion but not by dynein depletion, consistent with their detachment from microtubules upon dynein knockdown. Together, these data support a model of Htt as a facilitator of dynein-mediated trafficking that may regulate the cytoskeletal association of dynamic organelles.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actins / metabolism
  • Cell Line, Tumor
  • Cytoskeleton / metabolism*
  • Dyneins / genetics*
  • Dyneins / metabolism
  • Endosomes / metabolism*
  • Gene Knockdown Techniques / methods
  • HeLa Cells
  • Humans
  • Huntingtin Protein
  • Lysosomal Membrane Proteins / metabolism
  • Lysosomes / metabolism*
  • Microtubule-Associated Proteins / metabolism
  • Microtubule-Associated Proteins / physiology
  • Microtubules / metabolism
  • Microtubules / physiology
  • Molecular Motor Proteins / genetics
  • Molecular Motor Proteins / metabolism*
  • Nerve Tissue Proteins / genetics*
  • Nerve Tissue Proteins / metabolism
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Organelles / metabolism
  • Polymerization
  • Protein Transport / physiology
  • RNA Interference

Substances

  • Actins
  • HTT protein, human
  • Huntingtin Protein
  • Lysosomal Membrane Proteins
  • Microtubule-Associated Proteins
  • Molecular Motor Proteins
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • Dyneins