Voltage-sensitive potassium channels expressed after 20-Hydroxyecdysone treatment of a mosquito cell line.

ABSTRACT

The goal of this research was to express receptors and ion channels in hormone-treated insect cell lines. Treatment of Anopheles gambiae Sua1B cells with 20-hydroxyecdysone showed an inhibition of cell growth over a time course of three days, with no change in cellular morphology. The effect of 20-hydroxyecdysone was enhanced in the presence of the potassium channel blocker 4-aminopyridine, but not tetraethylammonium. Concentration-response curves of 4-aminopyridine in the presence of 42 µM (1 mg/ml) 20-hydroxyecdysone showed similar IC50 values (6-10 µM) across 3 day exposures. Whole cell patch clamp confirmed the expression of delayed-rectifier (Kv2) potassium channels in hormone-supplemented Sua1B cells, whereas untreated Sua1B cells showed no evidence of Kv2 expression. The hormone-induced expression of Kv2 channels occurred in as little as 4 h after treatment, but were not observed after 24 h of exposure to 20-hydroxyecdysone, suggesting they played a role in cell death. The expressed channels had current-voltage relationships diagnostic for the Kv2 subtype, and were inhibited with an IC50 = 13 mM of tetraethylammonium. Overall, these parameters were similar to Anopheles gambiae Kv2 potassium channels expressed in HEK-293 cells. The induced presence of ion channels (and possibly receptors) in these cells has potential utility for high throughput screening and basic neuroscience research.