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A proteasome-sensitive connection between PSD-95 and GluR1 endocytosis
1California Institute of Technology, HHMI, Division of Biology, MC 114-96, Pasadena, CA, 91125, USA.
Neuropharmacology
|October 2, 2004
Summary
The ubiquitin-proteasome system (UPS) regulates glutamate receptor (GluR) endocytosis by decreasing PSD-95 levels. PSD-95 degradation is crucial for GluR internalization, though direct ubiquitination remains undetected.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Synaptic transmission relies on regulating synaptic glutamate receptors (GluRs) via endocytosis and exocytosis.
- The ubiquitin-proteasome system (UPS) is essential for ligand-stimulated GluR internalization.
Purpose of the Study:
- To investigate if PSD-95 is a target of the UPS.
- To understand the role of PSD-95 in regulating GluR endocytosis.
Main Methods:
- Measuring PSD-95 levels and GluR1 internalization in neurons after neurotransmitter stimulation.
- Utilizing proteasome inhibitors and dominant-negative ubiquitin.
- Overexpressing PSD-95.
- Assessing PSD-95 ubiquitination under specific experimental conditions.
Main Results:
- Neurotransmitter stimulation negatively correlated PSD-95 levels with internalized GluR1.
- Dendritic PSD-95 decreased in a proteasome-dependent manner following stimulation.
- Overexpression of PSD-95 inhibited neurotransmitter-stimulated GluR1 endocytosis.
- No direct polyubiquitination of PSD-95 was detected, suggesting indirect regulation or transient ubiquitination.
Conclusions:
- PSD-95 levels are regulated by the UPS, impacting GluR endocytosis.
- The proteasomal degradation of PSD-95, potentially via an intermediate protein, is critical for synaptic plasticity.
- Further research is needed to elucidate the precise mechanism of PSD-95 regulation by the UPS.