Grant: Project Grant

Neurodevelopmental disorders (NDDs), such as intellectual disability and epilepsy, are highly prevalent, heterogeneous brain conditions that are often associated with gene mutations. Haploinsufficiency of the gene SCN1A, coding for the alpha subunit of the voltage-gated sodium channel, is one of the representative causes of epileptic encephalopathy and severe neurodevelopmental conditions. SCN1A haploinsufficiency produces insufficient SCN1A mRNA and protein, and reduces excitability in GABAergic inhibitory interneurons. The reduced excitability of interneurons results in seizure disorders and compromised development and function of the brain. Experimental evidence from conditional knock-in mouse strains offers promise toward the reversal of seizures and behavioral abnormalities related to the loss of the mouse Scn1a gene. These specific mouse strains were engineered in embryonic stem cells to make it a knock-out mouse in which Scn1a expression could be turned back on at a later time point through a Cre recombinase-dependent manner. Direct, translational approaches that allow for efficient, in vivo restoration of the SCN1A gene and rescue of neural and behavioral abnormalities in genetic haploinsufficiency remain to be expanded and demonstrated. We recently engineered and refined a CRISPR/dCas9-based toolkit compatible with a single AAV vector for in vivo delivery and transcriptional activation of the mouse Scn1a gene. In this grant, we will determine how restoring Scn1a gene expression through AAV-mediated transcriptional activation would correct sodium channel function, interneuron activities, rescue seizure, and behavioral deficits in a mouse model of Scn1a haploinsufficiency. We will further examine how an AAV-mediated transcriptional activation strategy can be harnessed to facilitate therapeutic development and mitigate neurodevelopmental disorders using the human neuronal model of SCN1A haploinsufficiency.