Rescuing Neurodevelopmental Deficits in AMPA Receptor Gain-of-Function Mutant.

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• AMPA receptors (AMPARs) are crucial for brain function and neuronal development.
• A recurrent variant in the AMPAR GluA1 subunit (GRIA1 p.A636T) is associated with autism spectrum disorder (ASD) and intellectual disability (ID).

Purpose of the Study:

• To investigate the causal role and mechanism of the GRIA1 p.A636T variant in ASD and ID.
• To explore RNA-targeted therapeutic interventions for neurodevelopmental disorders.

Main Methods:

• Generated a GRIA1-A636T knock-in mouse model to study the variant's effects.
• Administered an allele-specific antisense oligonucleotide to silence the mutant GRIA1 transcript in neonatal mice.

Main Results:

• Mutant mice displayed ASD/ID-like behaviors and hippocampal pathology, including dendritic atrophy and neuronal loss.
• AMPARs in mutant mice showed synaptic hyperexcitability and failed to transition to calcium-impermeable forms, leading to excitotoxicity.
• Neonatal antisense oligonucleotide treatment prevented pathology and improved behavioral deficits.

Conclusions:

• The GRIA1 p.A636T variant acts as a gain-of-function mutation, driving developmental excitotoxicity.
• RNA-targeted precision medicine, specifically antisense oligonucleotides, shows promise for treating neurodevelopmental disorders caused by specific genetic variants.