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Synapsins as regulators of neurotransmitter release
S Hilfiker1, V A Pieribone, A J Czernik
1Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, NY 10021, USA.
Summary
Synapsins, abundant presynaptic vesicle proteins, tether vesicles to actin, maintaining a reserve pool. Disrupting synapsin function impairs this pool and neurotransmitter release, revealing dual roles in synaptic transmission.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Neuronal transmission relies on presynaptic proteins regulating synaptic vesicle dynamics.
- Synapsins are neuron-specific phosphoproteins, abundant on synaptic vesicles.
- Synapsins interact with vesicle components and cytoskeletal proteins like actin.
Purpose of the Study:
- To elucidate the roles of synapsins in synaptic vesicle regulation and neurotransmitter release.
- To understand the molecular mechanisms underlying synapsin function in presynaptic terminals.
Main Methods:
- In vitro studies of synapsin interactions with vesicle and cytoskeletal components.
- Perturbation studies of synapsin function in various preparations, including the squid giant synapse.
Main Results:
- Synapsins tether synaptic vesicles to actin, forming a reserve pool near the active zone.
- Perturbation of synapsin function disrupts the reserve pool, increasing synaptic depression.
- Synapsin perturbation also inhibits and slows neurotransmitter release kinetics, indicating a role beyond reserve pool maintenance.
Conclusions:
- Synapsins play a dual role in exocytosis: maintaining the reserve vesicle pool and directly modulating neurotransmitter release downstream of vesicle docking.
- These functions are crucial for sustained neurotransmitter release during high neuronal activity.