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Determining Genetic Expression Profiles in C. elegans Using Microarray and Real-time PCR
Published on: July 30, 2011
UNC-13 is required for synaptic vesicle fusion in C. elegans
J E Richmond1, W S Davis, E M Jorgensen
1Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112-0840, USA.
Nature Neuroscience
|October 20, 1999
Summary
The UNC-13 protein is crucial for neurotransmitter release at synapses in C. elegans. Mutants lacking UNC-13 show docked vesicles but fail to release them, indicating a role in vesicle fusion or priming.
Area of Science:
- Neurobiology
- Molecular Biology
- Genetics
Background:
- Synaptic transmission relies on the regulated release of neurotransmitters from vesicles.
- The UNC-13 protein is known to play a role in synaptic vesicle exocytosis.
Purpose of the Study:
- To investigate the precise function of UNC-13 in synaptic vesicle release at the neuromuscular junction in C. elegans.
Main Methods:
- Analysis of unc-13 mutants in C. elegans.
- Examination of nervous system architecture and synapse morphology.
- Whole-cell, voltage-clamp recordings to assess synaptic release.
- Assays for spontaneous release and response to hyperosmotic stimulation.
Main Results:
- UNC-13 mutants exhibited normal nervous system architecture and synapse density.
- Synaptic vesicle numbers were increased two- to threefold in unc-13 mutants.
- Evoked neurotransmitter release was nearly abolished in unc-13 null alleles.
- Docked vesicles in mutants were incompetent for release, even under stimulation.
Conclusions:
- UNC-13 is essential for evoked neurotransmitter release.
- These findings support models where UNC-13 mediates vesicle priming or fusion during exocytosis.
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01:33Overview of Secretory Vesicles
Secretory vesicles, also known as dense core vesicles (DCVs), are membrane-bound vesicles that transport secretory proteins, such as hormones or neurotransmitters. Regulated secretory vesicles transport proteins from the trans-Golgi network to the exterior of the cell. Proteins present in regulated secretory vesicles are required to be rapidly exocytosed in large amounts upon a specific stimulus.
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01:26Fusion of Secretory Vesicles with the Plasma Membrane
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
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01:43SNAREs and Membrane Fusion
Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
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