NMDA receptors mediate calcium-dependent, bidirectional changes in dendritic PICK1 clustering

Area of Science:

• Neuroscience
• Synaptic Plasticity
• Molecular Biology

Background:

• AMPA receptor (AMPAR) trafficking is crucial for synaptic function and plasticity in the central nervous system (CNS).
• The GluR2-interacting protein, PICK1, is implicated in AMPAR endocytosis and synaptic targeting.
• Existing models suggest PICK1 and PKC cotargeting mediates AMPAR endocytosis.

Purpose of the Study:

• To investigate the role of NMDA receptor (NMDAR) activation in regulating surface AMPAR levels.
• To elucidate the mechanisms by which NMDARs influence the localization and function of PICK1.
• To understand how PICK1 redistribution contributes to bidirectional changes in AMPAR trafficking.

Main Methods:

• Utilized primary neuronal cultures.
• Investigated PICK1 redistribution and its association with GluR2 upon NMDAR activation.
• Employed small interfering RNA (siRNA) targeting PICK1 to assess its functional role.
• Measured changes in surface AMPAR levels.
• Correlated PICK1 localization with dendritic calcium signals.

Main Results:

• NMDAR activation induces bidirectional changes in surface AMPARs.
• NMDAR activation leads to increased endosomal PICK1 clustering during AMPAR endocytosis.
• Stronger NMDAR activation reduces PICK1 clustering, decreases PICK1/GluR2 association, and increases surface AMPARs.
• PICK1-siRNA mimics the effect of NMDAR activation on surface AMPARs, confirming PICK1's role.
• The magnitude of NMDAR-activated calcium signals dictates PICK1 localization changes.

Conclusions:

• PICK1 localization in dendrites is dynamically regulated by NMDAR activity.
• NMDAR-mediated bidirectional changes in PICK1 localization contribute to the regulation of surface AMPAR expression.
• PICK1 likely modulates the intracellular pool of AMPARs, influencing synaptic strength.