Development of recombinant cell line co-expressing mutated nav1.5, Kir2.1, and hERG for the safety assay of drug candidates

Abstract

To provide a high-throughput screening method for human ether-a-go-go-gene-related gene (hERG) K+ channel inhibition, a new recombinant cell line, in which single action potential (AP)-induced cell death was produced by gene transfection. Mutated human cardiac Na+ channel Nav1.5 (IFM/Q3), which shows extremely slow inactivation, and wild-type inward rectifier K+ channel, Kir2.1, were stably co-expressed in HEK293 cells (IFM/Q3+Kir2.1). In IFM/Q3+Kir2.1, application of single electrical stimulation (ES) elicited a long AP lasting more than 30 s and led cells to die by more than 70%, whereas HEK293 co-transfected with wild-type Nav1.5 and Kir2.1 fully survived. The additional expression of hERG K+ channels in IFM/Q3+Kir2.1 shortened the duration of evoked AP and thereby markedly reduced the cell death. The treatment of the cells with hERG channel inhibitors such as nifekalant, E-4031, cisapride, terfenadine, and verapamil, recovered the prolonged AP and dose-dependently facilitated cell death upon ES. The EC50 values to induce the cell death were 3 μM, 19 nM, 17 nM, 74 nM, and 3 μM, respectively, whereas 10 μM nifedipine did not induce cell death. Results indicate the high utility of this cell system for hERG K+ channel safety assay. © 2012 Society for Laboratory Automation and Screening.