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Local calcium release in dendritic spines required for long-term synaptic depression
M Miyata1, E A Finch, L Khiroug
1Laboratory for Cellular Neurophysiology, Brain Science Institute, RIKEN, Saitama, Japan.
Neuron
|November 22, 2000
Summary
Inositol trisphosphate (IP3) signaling in dendritic spines is crucial for long-term synaptic depression (LTD). Local IP3-mediated calcium release within spines is necessary for LTD, highlighting spines
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Dendritic spines are critical sites for synaptic plasticity.
- Inositol trisphosphate (IP3)-mediated calcium (Ca2+) signaling plays a role in neuronal function.
- The precise localization of IP3 receptors and endoplasmic reticulum within spines is not fully understood.
Purpose of the Study:
- To investigate the role of IP3-mediated Ca2+ signaling within dendritic spines.
- To determine the necessity of local IP3-mediated Ca2+ release for synaptic plasticity, specifically long-term synaptic depression (LTD).
Main Methods:
- Utilized mutant rats and mice lacking functional myosin-Va, which affects organelle transport.
- Examined parallel fiber synapses on cerebellar Purkinje cells in these mutant models.
- Assessed synaptic function, including LTD, and Ca2+ signaling dynamics in dendritic spines.
Main Results:
- Mutant mice lacking myosin-Va showed absent LTD at parallel fiber synapses.
- The endoplasmic reticulum and IP3 receptors were excluded from postsynaptic spines in these mutants.
- Restoring local Ca2+ release via photolysis of a caged Ca2+ compound rescued LTD.
Conclusions:
- Local IP3-mediated Ca2+ release within dendritic spines is essential for inducing LTD.
- Dendritic spines serve to compartmentalize IP3-mediated Ca2+ signaling to specific subcellular domains.
- Myosin-Va plays a role in targeting the endoplasmic reticulum and IP3 receptors to dendritic spines for synaptic plasticity.