Evaluation of positive allosteric modulators of SK2 channels using QPatch

Small-conductance Ca²⁺-activated K⁺ (SK) channels mediate afterhyperpolarization in neurons and dampen the firing frequency of action potentials. Calmodulin is constitutively associated with the SK2 channels and serves as the Ca²⁺ sensor for the SK-calmodulin complex. The SK2 channel subtype plays a key role in the regulation of excitability of Purkinje cells in the cerebellum. Given their importance in Purkinje cells, SK2 channels are a promising drug target for ataxia, a movement disorder.

Automated patch clamp (APC) machines, such as QPatch, have been used in the pharmaceutical industry to study drug interaction with varieties of ion channels. Over the past decade, technology has contributed significantly to pharmaceutical research and drug discovery. Here, we report to use QPatch as a tool for testing and evaluating the positive allosteric modulators of SK2 channels. A stable cell line of the rat SK2 channel tagged with GFP was established through transfection of HEK293 cells followed by puromycin selection and enrichment using repeated GFP fluorescence-activated cell sorting.

Positive allosteric modulators were tested under whole-cell voltage-clamp configuration with automated QPatch. The compounds that positively modulate the SK2 channels in the automated QPatch was further tested with the inside-out patch manual recordings. The results from automated whole-cell recordings and inside-out patch manual recordings were consistent.