Mechanism underlying activity-dependent insertion of TrkB into the neuronal surface

J Cell Sci. 2009 Sep 1;122(Pt 17):3123-36. doi: 10.1242/jcs.047712. Epub 2009 Aug 11.

Abstract

Activity-dependent insertion of tyrosine kinase receptor type 2 (TrkB receptor) into the plasma membrane can explain, in part, the preferential effect of brain-derived neurotrophic factor (BDNF) on active neurons; however, the detailed cellular and molecular mechanisms underlying this process are still unclear. In our study, we developed a fluorescence ratiometric assay for surface TrkB receptors to investigate the mechanisms of recruitment of TrkB to the plasma membrane following chemical long-term potentiation (cLTP) induction. We found that, in hippocampal neurons, the effect of cLTP-induced TrkB surface-recruitment occurred predominantly on neurites with rapid kinetics (t(1/2) of approximately 2.3 minutes) and was dependent on an intact cytoskeleton structure. Mutagenesis studies revealed that the juxtamembrane domain of TrkB is necessary and sufficient for its activity-dependent insertion into the plasma membrane. Moreover, we found that the phosphorylation of TrkB receptor at the Ser478 site by cyclin-dependent kinase 5 (Cdk5) is essential for cLTP-induced TrkB insertion into the neuronal surface. Finally, the degree of cLTP-induced TrkB surface-recruitment is higher in postsynaptic regions, which provides a potential mechanism for rapid enhancement of postsynaptic sensitivity to incoming BDNF signaling. Our studies provide new insights regarding neuronal activity-dependent surface delivery of TrkB receptor, which will advance our understanding of the modulatory role of TrkB in synaptic plasticity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Membrane / chemistry
  • Cell Membrane / genetics
  • Cell Membrane / metabolism*
  • Cells, Cultured
  • Cyclin-Dependent Kinase 5 / genetics
  • Cyclin-Dependent Kinase 5 / metabolism
  • Hippocampus / chemistry
  • Hippocampus / cytology
  • Hippocampus / metabolism
  • Kinetics
  • Neurons / chemistry
  • Neurons / metabolism*
  • Phosphorylation
  • Protein Structure, Tertiary
  • Protein Transport
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, trkB / chemistry
  • Receptor, trkB / genetics
  • Receptor, trkB / metabolism*

Substances

  • Receptor, trkB
  • Cyclin-Dependent Kinase 5