Abstract
The secretion of neurotransmitters and neuropeptides is mediated by distinct organelles-synaptic vesicles (SVs) and dense-core vesicles (DCVs), respectively. Relatively little is known about the factors that differentially regulate SV and DCV secretion. Here we show that protein kinase C-1 (PKC-1), which is most similar to the vertebrate PKC eta and epsilon isoforms, regulates exocytosis of DCVs in Caenorhabditis elegans motor neurons. Mutants lacking PCK-1 activity had delayed paralysis induced by the acetylcholinesterase inhibitor aldicarb, whereas mutants with increased PKC-1 activity had more rapid aldicarb-induced paralysis. Imaging and electrophysiological assays indicated that SV release occurred normally in pkc-1 mutants. By contrast, genetic analysis of aldicarb responses and imaging of fluorescently tagged neuropeptides indicated that mutants lacking PKC-1 had reduced neuropeptide secretion. Similar neuropeptide secretion defects were found in mutants lacking unc-31 (encoding the protein CAPS) or unc-13 (encoding Munc13). These results suggest that PKC-1 selectively regulates DCV release from neurons.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Aldicarb / pharmacology
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Animals
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Animals, Genetically Modified
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Caenorhabditis elegans
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Caenorhabditis elegans Proteins / physiology*
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Carrier Proteins
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Cholinesterase Inhibitors / pharmacology
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Cloning, Molecular / methods
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Diagnostic Imaging / methods
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Dose-Response Relationship, Radiation
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Electric Stimulation / methods
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Exocytosis / drug effects
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Exocytosis / genetics
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Gene Expression / genetics
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Green Fluorescent Proteins / metabolism
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Membrane Potentials / drug effects
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Membrane Potentials / physiology
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Membrane Potentials / radiation effects
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Motor Neurons / drug effects
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Motor Neurons / metabolism*
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Muscles / drug effects
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Muscles / metabolism
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Mutant Proteins / physiology
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Neuropeptides / metabolism*
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Patch-Clamp Techniques / methods
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Protein Kinase C / physiology*
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Secretory Vesicles / drug effects
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Secretory Vesicles / physiology
Substances
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Caenorhabditis elegans Proteins
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Carrier Proteins
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Cholinesterase Inhibitors
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Mutant Proteins
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Neuropeptides
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phorbol ester binding protein
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Green Fluorescent Proteins
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Aldicarb
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Protein Kinase C