Ca(2+)-calmodulin signalling pathway up-regulates GABA synaptic transmission through cytoskeleton-mediated mechanisms.
We investigated the role of calcium (Ca(2+))/calmodulin (CaM) signaling pathways in modulating GABA synaptic transmission at CA1 pyramidal neurons in hippocampal slices. Whole-cell pipettes were used to record type A GABA receptor (GABA(A)R)-gated inhibitory postsynaptic currents (IPSCs) and to perfuse intracellularly modulators in the presence of glutamate receptor antagonists. GABA(A)R-gated IPSCs were enhanced by the postsynaptic infusions of adenophostin (1 microM), a potent agonist of inositol-1,4,5-triphosphate receptor (IP(3)R) that induces Ca(2+) release. The enhancement was blocked by co-infusing either 1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (10 mM) or CaM-binding peptide (100 microM). Moreover, the postsynaptic infusion of Ca(2+)-CaM (40/10 microM) enhanced both evoked and spontaneous GABA(A)R-gated IPSCs. The enhancement was attenuated by co-infusing 100 microM CaM-KII(281-301), an autoinhibitory peptide of CaM-dependent protein kinases. These results indicate that postsynaptic Ca(2+)-CaM signaling pathways essentially enhance GABAergic synaptic transmission. In the investigation of synaptic targets for the enhancement, we found that IP(3)R agonist-enhanced GABA(A)R-gated IPSCs were attenuated by co-infusing colchicine (30 microM), vincristine (3 microM) or cytochalasin D (1 microM) that inhibits tubulin or actin polymerization, implying that actin filament and microtubules are involved. We conclude that postsynaptic Ca(2+)-CaM signaling pathways strengthen the function of GABAergic synapses via a cytoskeleton-mediated mechanism, probably the recruitment of receptors in the postsynaptic membrane.
The Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
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J
Wei
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Zhang
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Zhu
J-H
JH
Wang
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D002147:Calmodulin; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium