PSD-95 is a major scaffolding protein of the postsynaptic density, tethering NMDA- and AMPA-type glutamate receptors to signaling proteins and the neuronal cytoskeleton. Here we show that PSD-95 is regulated by the ubiquitin-proteasome pathway. PSD-95 interacts with and is ubiquitinated by the E3 ligase Mdm2. In response to NMDA receptor activation, PSD-95 is ubiquitinated and rapidly removed from synaptic sites by proteasome-dependent degradation. Mutations that block PSD-95 ubiquitination prevent NMDA-induced AMPA receptor endocytosis. Likewise, proteasome inhibitors prevent NMDA-induced AMPA receptor internalization and synaptically induced long-term depression. This is consistent with the notion that PSD-95 levels are an important determinant of AMPA receptor number at the synapse. These data suggest that ubiquitination of PSD-95 through an Mdm2-mediated pathway is critical in regulating AMPA receptor surface expression during synaptic plasticity.
Pubmed ID: 14642282 RIS Download
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Image processing software used to modify and clarify sample images for FluoView FV1000 range of confocal laser scanning microscopes and Fluoview FV1000MPE multiphoton excitation systems. The software incorporates high-dynamic-range imaging, minimized signal-to-noise ratios, partial stitching with multiarea time-lapse imaging, and channel unmixing. The software also allows users to select specific areas of the whole sample, which can stitched together.
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