Increased glycine contributes to synaptic dysfunction and early mortality in Nprl2 seizure model

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Epilepsies linked to the mTORC1 pathway regulator GATOR1 lack targeted therapies.
• Mutations in GATOR1 subunits, such as NPRL2, are associated with epilepsy.
• Understanding NPRL2's role is crucial for developing new epilepsy treatments.

Purpose of the Study:

• To investigate the molecular and electrophysiological mechanisms of NPRL2-related epilepsy.
• To create and analyze a mouse model with neocortical loss of Nprl2.

Main Methods:

• Generation of a mouse model with neocortical Nprl2 loss.
• Electrophysiological recordings to assess synaptic function.
• Proteomic and metabolomic analyses to identify molecular changes.
• Investigation of glycine's role in NMDA receptor function.

Main Results:

• Nprl2 mutant mice exhibited increased mTORC1 signaling and spontaneous seizures.
• Abnormal synaptic function was observed, with altered excitatory and inhibitory synaptic currents.
• Proteomic and metabolomic studies revealed changes in epilepsy-related proteins and metabolites, including increased glycine.
• Glycine's action on NMDA receptors contributed to the observed phenotypes.

Conclusions:

• Neuronal Nprl2 loss leads to mTORC1-related epilepsy through molecular, metabolic, and electrophysiological alterations.
• Increased glycine signaling via NMDA receptors plays a significant role in the disease phenotype.
• This study provides insights into potential therapeutic targets for GATOR1-related epilepsies.