NMDAR-Activated PP1 Dephosphorylates GluN2B to Modulate NMDAR Synaptic Content

Area of Science:

• Neuroscience
• Molecular Biology
• Cellular Signaling

Background:

• Postsynaptic N-methyl-D-aspartate receptors (NMDARs) exist in synaptic and extrasynaptic populations in mature neurons.
• These receptor pools communicate via lateral diffusion, influencing synaptic NMDAR levels.
• Dynamic regulation of NMDAR synaptic content is crucial for neuronal function.

Purpose of the Study:

• To identify molecular mechanisms controlling NMDAR synaptic content.
• To investigate the role of GluN2B subunit phosphorylation in NMDAR trafficking.
• To elucidate the involvement of protein phosphatase 1 (PP1) in activity-dependent NMDAR regulation.

Main Methods:

• Investigated the phosphorylation status of the GluN2B subunit of NMDARs at S1480.
• Examined the interaction of phosphorylated GluN2B with protein phosphatase 1 (PP1).
• Assessed the impact of NMDAR activation on PP1 activity and GluN2B dephosphorylation.

Main Results:

• Phosphorylation of GluN2B at S1480 anchors NMDARs to extrasynaptic sites within a PP1 complex.
• Global NMDAR activation triggers PP1 activation.
• Activated PP1 dephosphorylates GluN2B at S1480, promoting increased synaptic NMDAR content.

Conclusions:

• PP1-mediated dephosphorylation of the GluN2B PDZ-ligand dynamically regulates synaptic NMDAR expression.
• This process is activity-dependent and crucial for synaptic plasticity, metaplasticity, and neurotransmission.
• Identified a key molecular switch for controlling NMDAR localization and synaptic function.