Functional evaluation of a rat model of KCNT1-related epilepsy

KCNT1 encodes a sodium-activated potassium channel, and its variant can lead to refractory epilepsy. The resistance to antiseizure medication in KCNT1 variant-related epilepsy suggests the presence of complex gene regulation. Our goal is to clarify the pathogenicity of a KCNT1 variant associated with epilepsy.

Here, we intended to characterize the pathogenicity of the Kcnt1-269 variant (c.805 G > A, c.807 G > C, p.G269S; corresponding to c.862 G > A, p.G288S in human) in vitro and in vivo, and to analyze the transcriptome of the rat cerebral cortex through RNA sequencing.

Our study revealed that homozygous Kcnt1-269 variant rats showed excessive neuroexcitability in CA1 pyramidal neurons, including enhanced neuronal action potential amplitudes, decreased action potential thresholds, and increased neuronal firing numbers. Homozygous and heterozygous Kcnt1-269 variant rats had high frequency of evoked action potential under different step currents. The cumulative dose of pentetrazol required to induce epileptic seizures in homozygous Kcnt1-269 variant rats was significantly lower compared with wild-type rats. Transcriptome analysis of the cerebral cortex identified 190 upregulated and 149 downregulated genes in heterozygous Kcnt1-269 variant rats compared with wild-type rats. Functional enrichment analysis revealed that "nucleolus," "neuropeptide signaling pathway," "dendrite," and "protein binding" were the most prominent Gene Ontology terms, while "neuroactive ligand-receptor interaction" was one of the most significant Kyoto Encyclopedia of Genes and Genomes terms.

Our findings elucidate the epileptogenicity of the Kcnt1-269 variant in rats and may provide new insights into the pathways associated with Kcnt1 variant-related epilepsy through transcriptome analysis.