hERG (Kv11.1) - HEK293 Recombinant Cell line

Human ERG channel has been stably expressed in HEK293 cell line and its expression was confirmed by Western blotting. The channel activity of hERG was characterized by a fluorescence-based assay using thallium influx as a surrogate indicator of potassium ion channel activity coupled with a thallium-sensitive fluorescent dye. When hERG-HEK293 cells were pre-loaded with thallium-sensitive dye and stimulated with stimulus buffer containing potassium/thallium, thallium ions flowed through the open hERG channels into the cells and bound the dye, generating a fluorescent signal. The hERG channel activity in hERG-HEK293 cells was blocked by hERG channel blockers, cisapride or dofetilide, causing the fluorescent signal triggered by thallium influx to drop to the basal level. hERG (human ether-a-go-go-related gene) encodes the alpha subunit of a potassium ion channel, Kv11.1. It contains six transmembrane alpha-helices with a re-entrant "poreloop" between the fifth and the sixth transmembrane helices. This ion channel is best known for its contribution to the electrical activity of the heart that coordinates the heart's beating. When this channel's ability to conduct electrical current across the cell membrane is inhibited or compromised, either by application of drugs or by rare mutations, it can result in a potentially fatal disorder called long QT syndrome. A number of clinically successful drugs in the market exhibit the potential to inhibit hERG, and create a concomitant risk of sudden death as a side-effect, which has made hERG inhibition an important off-target that must be avoided during drug development.