PI-3 Kinase and IP3 Are Both Necessary and Sufficient to Mediate NT3-induced Synaptic Potentiation

Nat Neurosci. 2001 Jan;4(1):19-28. doi: 10.1038/82858.

Abstract

Signaling mechanisms underlying neurotrophic regulation of synaptic transmission are not fully understood. Here we show that neurotrophin-3 (NT3)-induced potentiation of synaptic transmission at the neuromuscular synapses is blocked by inhibition of phosphoinositide-3 kinase, phospholipase C-gamma or the downstream IP3 receptors of phospholipase C-gamma, but not by inhibition of MAP kinase. However, neither stimulation of Ca2+ release from intracellular stores by photolysis of caged IP3, nor expression of a constitutively active phosphoinositide-3 kinase (PI3K*) in presynaptic motoneurons alone is sufficient to enhance transmission. Photo-uncaging of IP3 in neurons expressing PI3K* elicits a marked synaptic potentiation, mimicking the NT3 effect. These results reveal an involvement of PI3 kinase in transmitter release, and suggest that concomitant activation of PI3 kinase and IP3 receptors is both necessary and sufficient to mediate the NT3-induced synaptic potentiation.

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Channels / metabolism
  • Cells, Cultured
  • Enzyme Activation / drug effects
  • Inositol 1,4,5-Trisphosphate / analogs & derivatives*
  • Inositol 1,4,5-Trisphosphate / metabolism*
  • Inositol 1,4,5-Trisphosphate / pharmacology
  • Inositol 1,4,5-Trisphosphate Receptors
  • Isoenzymes / metabolism
  • Long-Term Potentiation / drug effects
  • Long-Term Potentiation / physiology*
  • Mitogen-Activated Protein Kinases / metabolism
  • Motor Neurons / cytology
  • Motor Neurons / drug effects
  • Motor Neurons / metabolism
  • Neuromuscular Junction / cytology
  • Neuromuscular Junction / embryology
  • Neuromuscular Junction / metabolism*
  • Neurotrophin 3 / metabolism*
  • Neurotrophin 3 / pharmacology
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phospholipase C gamma
  • Photolysis
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Signal Transduction / drug effects
  • Synaptic Transmission / physiology
  • Type C Phospholipases / metabolism
  • Xenopus

Substances

  • Calcium Channels
  • Inositol 1,4,5-Trisphosphate Receptors
  • Isoenzymes
  • Neurotrophin 3
  • Receptors, Cytoplasmic and Nuclear
  • inositol 1,4,5-trisphosphate 1-(2-nitrophenyl)ethyl ester
  • Inositol 1,4,5-Trisphosphate
  • Phosphatidylinositol 3-Kinases
  • Mitogen-Activated Protein Kinases
  • Type C Phospholipases
  • Phospholipase C gamma
  • Calcium