Titration of KATP channel expression in mammalian cells utilizing recombinant baculovirus transduction

A variety of transfection approaches have been used to deliver plasmids encoding ion channel genes into cells. We have used the baculovirus transduction system, BacMam, to demonstrate transient expression of multi-subunit K-ATP channels in CHO-K1 and HEK-293 EBNA cells using sulfonylurea receptor 1 (SUR), SUR2A, SUR2B, and K(IR)6.2 genes. [H-3]-glyburide binding, patch clamp, and DiBAC(4)(3) measurements of membrane potential changes were used to monitor channel expression. BacMam delivery of each SUR isoform with K(IR)6.2 was demonstrated based on its pharmacological profiles. Expression levels of SUR1 and K(IR)6.2 were titrated by varying the viral concentration or time of virus addition, with functional activity measured in as little as 4-6 hours posttransduction. Further increases in BacMam virus induced sufficient K-ATP expression to dominate membrane potential without pharmacological opening of the channel. Independently altering treatment with virus containing either the SUR1 or K(IR)6.2 gene revealed interactions among subunits during formation of functional channels in the plasma membrane. This study demonstrates the utility and versatility of BacMam as a valuable gene delivery tool for the study of ion channel function.