This project seeks to explore if anti-seizure drugs (ASDs) can act as chaperones for voltage-gated sodium channel (VGSC) subunit proteins to which they don’t bind directly, by testing if they are able to rescue epilepsy-related trafficking deficient variants in SCN1B, encoding the β1/β1B subunits.

Some epilepsy-related variants in VGSC subunit genes result in trafficking deficient proteins that are retained in the endoplasmic reticulum. Previous findings show that certain ASDs are able to rescue VGSC trafficking deficient mutant α subunit proteins, to which they are known to bind to exert their anticonvulsant effects.

This study utilizes in vitro mammalian cell cultures (1610 cells) that stably express the SCN1B-p.R125C β₁ trafficking deficient mutant cell, with cells expressing the wild-type (WT) subunit used as controls. After incubation for 48 hours with selected ASDs (phenytoin, carbamazepine, or valproic acid), cells were tested for surface expression of p.R125C β₁ using biotinylated cell-surface samples and analyzed using western blotting. Whole cell lysates were also probed with western blotting to control for protein expression.

Under naïve culture conditions, 1610 cells expressed robust amounts of WT β₁ and p.R125C β₁ in cell lysates, but only WT β₁ was present at the cell surface, consistent with previous reports. Preliminary findings of cell culture with all selected ASDs resulted in detectible expression of p.R125C β₁ at the cell surface, without any effects on the overall expression of WT or mutant subunits.

Although preliminary, these results suggest the ability of the selected ASDs to act as chaperones even for VGSC proteins to which they do not bind directly to exert their anti-seizure effect. Future studies will aim to confirm these findings and explore the spectrum of proteins for which ASDs can exert a chaperone function.