Chris Bostick, Columbia University Medical Center, Institute for Genomic Medicine
Conference: Society for Neuroscience 2017, Washington DC
Abstract Title: Characterization and Therapeutic Screening of a Gain of Function Mutation in KCNT1 Utilizing Multielectrode Arrays
Abstract: De novo mutations in the C-terminal domain of the KCNT1 sodium activated potassium channel have been implicated in multiple early-onset epileptic encephalopathies including Malignant Migrating Partial Seizures of Infancy (MMPSI) and Autosomal Dominant Nocturnal Frontal Lobe Epilepsy (ADNFLE). KCNT1 channels are known to contribute to a late afterhyperpolarization after repetitive stimulation and regulation of neuronal excitability and adaptation. While studies utilizing heterologous expression systems have demonstrated a gain of function underlies the mechanism of these de novo mutations, there still remain many questions about the resulting hyperexcitability pathology seen in vivo. To this end we have characterized mouse models including a knock-in (ki) gain of function Kcnt1 mutation (Y777H) generated by CRISPR/Cas9 in the JAX Center for Precision Genetics based on an individual with moderate ADNFLE. Homozygous ki mice exhibit spontaneous generalized tonic-clonic seizures in video-EEG, as well as a modestly lower seizure threshold. In addition, in vitro studies have been conducted on mouse primary cortical neurons utilizing Multielectrode Arrays (MEA). MEA allows noninvasive measurement of neuronal activity, and has recently been adopted to study aberrant neuronal network activity associated with genetic variants. The multi-well format yields the ability for medium throughput screening for therapeutics in the treatment of various neuronal pathologies. Studies on the spontaneous activity of homozygous ki primary cortical neurons demonstrate increased firing and bursting during neuronal network maturation in homozygous neurons as well as increased neuronal activity during burst and network events post network maturation. In addition, preliminary work has demonstrated that Y777H homozygotes have greater evoked responses to electrical stimulation compared to wildtype control. Utilizing this platform, we will screen candidate therapies from an FDA approved library searching for effective targeted treatments to further assess in vivo.