Effects of PKA-mediated phosphorylation of Snapin on synaptic transmission in cultured hippocampal neurons.
Use-dependent activation of protein kinase A (PKA) modulates transmitter release, contributing to synaptic plasticity. Snapin, a PKA substrate in neurons, associates with the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, and its phosphorylation leads to increased binding of synaptotagmin to the SNARE complex. We investigated the role of PKA-dependent phosphorylation of Snapin in hippocampal neurons. Overexpression of Snapin S50D, a mutant mimicking the phosphorylated state, resulted in a decreased number of readily releasable vesicles. In addition, both the release probability of individual vesicles and the depression rate during high-frequency stimulation were increased. Overexpression of Snapin S50A, a mutant that cannot be phosphorylated, did not alter the size of the pool or the probability of release. Furthermore, dialysis of Sp-cAMPS, a nonhydrolyzable analog of cAMP that will promote phosphorylation by PKA, also led to increased synaptic depression in cells overexpressing wild-type Snapin. These results establish Snapin as an important target of PKA in CNS synapses and indicate a role for Snapin in the plasticity of transmitter release.
Physiologisches Institut, Universität des Saarlandes, 66424 Homburg/Saar, Germany.
Pratima
P
Thakur
David R
DR
Stevens
Zu-Hang
ZH
Sheng
Jens
J
Rettig
D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials; D006624:Hippocampus / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D009154:Mutation; D009473:Neuronal Plasticity; D009474:Neurons / Q000201:enzymology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D009435:Synaptic Transmission; D013572:Synaptic Vesicles / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
C118519:SNAPIN protein, human; D033921:Vesicular Transport Proteins; D017868:Cyclic AMP-Dependent Protein Kinases