Essential role of Hrs in endocytic recycling of full-length TrkB receptor but not its isoform TrkB.T1

J Biol Chem. 2009 May 29;284(22):15126-36. doi: 10.1074/jbc.M809763200. Epub 2009 Apr 7.

Abstract

Brain-derived neurotrophic factor (BDNF) signaling through its receptor, TrkB, modulates survival, differentiation, and synaptic activity of neurons. Both full-length TrkB (TrkB-FL) and its isoform T1 (TrkB.T1) receptors are expressed in neurons; however, whether they follow the same endocytic pathway after BDNF treatment is not known. In this study we report that TrkB-FL and TrkB.T1 receptors traverse divergent endocytic pathways after binding to BDNF. We provide evidence that in neurons TrkB.T1 receptors predominantly recycle back to the cell surface by a "default" mechanism. However, endocytosed TrkB-FL receptors recycle to a lesser extent in a hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs)-dependent manner which relies on its tyrosine kinase activity. The distinct role of Hrs in promoting recycling of internalized TrkB-FL receptors is independent of its ubiquitin-interacting motif. Moreover, Hrs-sensitive TrkB-FL recycling plays a role in BDNF-induced prolonged mitogen-activated protein kinase (MAPK) activation. These observations provide evidence for differential postendocytic sorting of TrkB-FL and TrkB.T1 receptors to alternate intracellular pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Brain-Derived Neurotrophic Factor / pharmacology
  • Cell Line
  • Endocytosis* / drug effects
  • Endosomal Sorting Complexes Required for Transport
  • Enzyme Activation / drug effects
  • Humans
  • Isoenzymes / metabolism
  • Kinetics
  • Ligands
  • Mitogen-Activated Protein Kinases / metabolism
  • Models, Biological
  • Phosphoproteins / chemistry
  • Phosphoproteins / metabolism*
  • Protein Processing, Post-Translational / drug effects
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, trkB / chemistry
  • Receptor, trkB / metabolism*
  • Signal Transduction / drug effects

Substances

  • Brain-Derived Neurotrophic Factor
  • Endosomal Sorting Complexes Required for Transport
  • Isoenzymes
  • Ligands
  • Phosphoproteins
  • hepatocyte growth factor-regulated tyrosine kinase substrate
  • Receptor, trkB
  • Mitogen-Activated Protein Kinases