Postsynaptic PKA Controls Quantal Size and Reveals a Retrograde Signal that Regulates Presynaptic Transmitter Release in Drosophila

Two distinct mechanisms regulate synaptic efficacy at the Drosophila neuromuscular junction (NMJ): a PKA-dependent modulation of quantal size and a retrograde regulation of presynaptic release. Postsynaptic expression of a constitutively active PKA catalytic subunit decreases quantal size, whereas o...

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Bibliographic Details
Published in:Neuron (Cambridge, Mass.) Mass.), 1998-02, Vol.20 (2), p.305-315
Main Authors: Davis, Graeme W, DiAntonio, Aaron, Petersen, Sophie A, Goodman, Corey S
Format: Article
Language:English
Subjects:
Animals
Cyclic AMP-Dependent Protein Kinases - antagonists & inhibitors
Cyclic AMP-Dependent Protein Kinases - genetics
Cyclic AMP-Dependent Protein Kinases - metabolism
Drosophila
Drosophila - physiology
Gene Expression Regulation, Enzymologic
Motor Neurons - enzymology
Mutagenesis
Neuromuscular Junction - enzymology
Neurotransmitter Agents - metabolism
Presynaptic Terminals - enzymology
Receptors, Glutamate - genetics
Synaptic Transmission - physiology
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Summary:Two distinct mechanisms regulate synaptic efficacy at the Drosophila neuromuscular junction (NMJ): a PKA-dependent modulation of quantal size and a retrograde regulation of presynaptic release. Postsynaptic expression of a constitutively active PKA catalytic subunit decreases quantal size, whereas overexpression of a mutant PKA regulatory subunit (inhibiting PKA activity) increases quantal size. Increased PKA activity also decreases the response to direct iontophoresis of glutamate onto postsynaptic receptors. The PKA-dependent modulation of quantal size requires the presence of the muscle-specific glutamate receptor DGluRIIA, since PKA-dependent modulation of quantal size is lost in homozygous viable DGluRIIA − mutants. Furthermore, elevated postsynaptic PKA reduces the quantal amplitude and the time constant of miniature excitatory junctional potential (mEJP) decay to values that are nearly identical to those observed in DGluRIIA − mutants. The PKA-dependent reduction in quantal size is accompanied developmentally by an increase in presynaptic quantal content, indicating the presence of a retrograde signal that regulates presynaptic release.
ISSN:0896-6273
1097-4199
DOI:10.1016/S0896-6273(00)80458-4