Limb-Clasping Response in NMDA Receptor Palmitoylation-Deficient Mice.

Area of Science:

• Neuroscience
• Molecular Biology
• Synaptic Plasticity

Background:

• Proper regulation of N-methyl-D-aspartate-type glutamate receptor (NMDA receptor) expression is vital for mammalian brain excitatory synaptic functions.
• Dysfunction of NMDA receptors is implicated in neuropsychiatric and neurodegenerative diseases.
• Posttranslational S-palmitoylation, the attachment of palmitic acid to cysteine residues, occurs at the carboxyl terminus of the GluN2B subunit of NMDA receptors.

Purpose of the Study:

• To investigate the role of S-palmitoylation of the GluN2B subunit in NMDA receptor regulation and its impact on brain function.
• To elucidate the consequences of impaired palmitoylation on NMDA receptor expression and synaptic function.
• To analyze the behavioral and neurological effects of specific mutations affecting GluN2B palmitoylation.

Main Methods:

• Generated GluN2B 3CS knock-in mice with mutations in three palmitoylatable cysteine residues.
• Assessed GluN2B Tyr1472 phosphorylation levels in the hippocampus and cerebral cortex.
• Quantified the surface expression of GluN2B-containing NMDA receptors.
• Evaluated behavioral responses, neurological reflexes, and synaptic protein expression in homozygous mice.

Main Results:

• Mutations of three palmitoylatable cysteine residues (3CS) in GluN2B led to dephosphorylation of GluN2B Tyr1472.
• This dephosphorylation resulted in reduced surface expression of GluN2B-containing NMDA receptors in the hippocampus and cerebral cortex.
• GluN2B 3CS homozygous mice exhibited a distinct clasping response, a behavioral disorder, without gross brain structural or general neurological abnormalities.

Conclusions:

• Palmitoylation-dependent regulation of NMDA receptors at excitatory synapses is essential for coordinating complex higher brain functions.
• The study demonstrates a direct link between GluN2B palmitoylation, receptor surface expression, and specific behaviors.
• Impaired NMDA receptor palmitoylation can lead to neurological dysfunction, underscoring its therapeutic potential.