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Synapsin I regulates glutamate release from rat brain synaptosomes
R A Nichols1, T J Chilcote, A J Czernik
1Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021.
Journal of Neurochemistry
|February 1, 1992
Summary
Dephosphorylated synapsin I, when introduced into rat brain synaptosomes, reduced glutamate release. Phosphorylated synapsin I had no effect, indicating its phosphorylation state is crucial for regulating neurotransmitter release.
Area of Science:
- Neuroscience
- Molecular Biology
- Cellular Neuroscience
Background:
- Synapsin I is a neuronal phosphoprotein involved in regulating neurotransmitter release.
- Its function is modulated by its phosphorylation state, particularly by Ca2+/calmodulin-dependent protein kinase II (CaMKII).
Purpose of the Study:
- To investigate the role of synapsin I's phosphorylation state in regulating glutamate release from synaptosomes.
- To determine if the entry of synapsin I into synaptosomes is necessary for its effect.
Main Methods:
- Rat brain synaptosomes were prepared.
- Freeze-thaw permeabilization was used to introduce dephosphorylated or phosphorylated synapsin I.
- Potassium-induced glutamate release was measured.
Main Results:
- Introduction of dephosphorylated synapsin I significantly decreased K(+)-induced glutamate release.
- Introduction of CaMKII-phosphorylated synapsin I had no effect on glutamate release.
- Adding dephosphosynapsin I after permeabilization did not affect glutamate release, highlighting the importance of entry into the synaptosome.
Conclusions:
- Synapsin I's regulatory role in neurotransmitter release is dependent on its phosphorylation state.
- The intracellular presence of synapsin I within synaptosomes is essential for its inhibitory effect on glutamate release.
- Synapsin I is implicated as a key regulator of neurotransmitter release in the mammalian nervous system.