Hippocampal Lnx1-NMDAR multiprotein complex mediates initial social memory.

Area of Science:

• Neuroscience
• Molecular Biology
• Developmental Biology

Background:

• Social interaction and communication are fundamental mammalian behaviors linked to neurodevelopmental disorders.
• Synaptic glutamate receptors and PDZ-binding proteins are implicated in sociability deficits, but their cellular specialization remains unclear.

Purpose of the Study:

• To identify key proteins involved in the cellular mechanisms of initial social behavior during postnatal development.
• To investigate the role of the PDZ scaffold protein Lnx1 in the hippocampus and its impact on social memory.

Main Methods:

• Gene targeting in mice to create Lnx1-deficient models.
• Electrophysiological recordings to assess neuronal activity and synaptic function.
• Analysis of NMDA receptor (NMDAR) function, GluN2B expression, and protein complex formation.

Main Results:

• Lnx1 deficiency caused hippocampal subregional dysfunction and impaired social memory in juvenile and adult mice.
• Lnx1 deletion led to NMDAR hypofunction, decreased GluN2B in the postsynaptic density, and disrupted the Lnx1-NMDAR-EphB2 complex.
• Restoring Lnx1 or EphB2 in the CA3 region rescued synaptic function and social memory.

Conclusions:

• Lnx1 is essential for initial social behavior and memory formation during adolescence.
• The postsynaptic NMDAR multiprotein complex, regulated by Lnx1 and EphB2, plays a critical role in establishing social memory.