Efficient expression of a cnidarian peptide-gated ion channel in mammalian cells.

Hydra Na⁺ channels (HyNaCs) are peptide-gated ion channels of the DEG/ENaC gene family that are directly activated by neuropeptides of the Hydra nervous system. They have previously been successfully characterized in Xenopus oocytes. To establish their expression in mammalian cells, we transiently expressed heteromeric HyNaC2/3/5 in human HEK 293 and monkey COS-7 cells. We found that the expression of HyNaC2/3/5 using native cDNAs was inefficient and that codon optimization strongly increased protein expression and current amplitude in patch-clamp experiments. We used the improved expression of codon-optimized channel subunits to perform Ca²⁺ imaging and to demonstrate their glycosylation pattern. In summary, we established efficient expression of a cnidarian ion channel in mammalian cell lines.