Postsynaptic TRPC1 function contributes to BDNF-induced synaptic potentiation at the developing neuromuscular junction

J Neurosci. 2011 Oct 12;31(41):14754-62. doi: 10.1523/JNEUROSCI.3599-11.2011.

Abstract

Brain-derived neurotrophic factor (BDNF) induces synaptic potentiation at both neuromuscular junctions (NMJs) and synapses of the CNS through a Ca2+ -dependent pathway. The molecular mechanism underlying BDNF-induced synaptic potentiation, especially the regulation of Ca2+ dynamics, is not well understood. Using the Xenopus NMJ in culture as a model system, we show that pharmacological inhibition or morpholino-mediated knockdown of Xenopus TRPC1 (XTRPC1) significantly attenuated the BDNF-induced potentiation of the frequency of spontaneous synaptic responses at the NMJ. Functionally, XTRPC1 was required specifically in postsynaptic myocytes for BDNF-induced Ca2+ elevation and full synaptic potentiation at the NMJ, suggesting a previously underappreciated postsynaptic function of Ca2+ signaling in neurotrophin-induced synaptic plasticity, in addition to its well established role at presynaptic sites. Mechanistically, blockade of the p75 neurotrophin receptor abolished BDNF-induced postsynaptic Ca2+ elevation and restricted BDNF-induced synaptic potentiation, while knockdown of the TrkB receptor in postsynaptic myocytes had no effect. Our study suggests that BDNF-induced synaptic potentiation involves coordinated presynaptic and postsynaptic responses and identifies TRPC1 as a molecular mediator for postsynaptic Ca2+ elevation required for BDNF-induced synaptic plasticity.

Publication types

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

MeSH terms

  • Animals
  • Brain-Derived Neurotrophic Factor / pharmacology*
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Coculture Techniques
  • Electric Stimulation / methods
  • Embryo, Nonmammalian
  • Female
  • Imidazoles / pharmacology
  • Male
  • Microscopy, Confocal
  • Morpholinos / pharmacology
  • Muscle Cells / drug effects
  • Neuromuscular Junction* / drug effects
  • Neuromuscular Junction* / embryology
  • Neuromuscular Junction* / physiology
  • Neurons / drug effects
  • Neurons / physiology
  • Patch-Clamp Techniques
  • Receptor, trkB / metabolism
  • Receptors, Nerve Growth Factor / metabolism
  • Spinal Cord / cytology
  • Synaptic Transmission / drug effects*
  • Synaptic Transmission / genetics
  • TRPC Cation Channels / genetics
  • TRPC Cation Channels / metabolism*
  • Xenopus
  • Xenopus Proteins / genetics
  • Xenopus Proteins / metabolism*

Substances

  • Brain-Derived Neurotrophic Factor
  • Calcium Channel Blockers
  • Imidazoles
  • Morpholinos
  • Receptors, Nerve Growth Factor
  • TRPC Cation Channels
  • TRPC1 protein, Xenopus
  • Xenopus Proteins
  • Receptor, trkB
  • 1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
  • Calcium