Kv4.2^V404M Mutation Induces Epileptiform Activity and Multiple Behavioral Abnormalities in Heterozygous Knock-in Mice

Area of Science:

• Neuroscience
• Genetics
• Channelopathies

Background:

• The KCND2 gene encodes the Kv4.2 subunit, crucial for neuronal excitability via the somatodendritic subthreshold A-type current (I_SA).
• A heterozygous missense mutation (V404M) in KCND2 is linked to early-onset epilepsy, autism, and global developmental delay in humans.

Purpose of the Study:

• To investigate the pathological role of the Kv4.2^V404M mutation.
• To establish and characterize a Kv4.2^(V404M/+) heterozygous knock-in mouse model.

Main Methods:

• CRISPR technology was used to generate Kv4.2^(V404M/+) heterozygous knock-in mice.
• Developmental, physiological, and behavioral features were compared between mutant and wild-type littermate controls.

Main Results:

• Kv4.2^(V404M/+) mice exhibited significant early mortality, poor reproduction, and reduced body weight in males.
• Altered I_SA function, frequent spike-wave epileptiform discharges (especially during NREM sleep), and elevated ΔFosB levels were observed.
• Behavioral assays revealed significant deficits in exploratory behavior, social interaction, fear conditioning, and spatial memory.

Conclusions:

• The Kv4.2^V404M mutation is sufficient to induce a dominant syndrome of epilepsy and aberrant behaviors in mice.
• This mouse model provides a valuable tool for understanding Kv4.2 dysfunction in neuropathology and for validating therapeutic strategies for human channelopathies.