Differential expression of ORCC and CFTR induced by low temperature in CF airway epithelial cells

When nonepithelial cell types expressing the ΔF508-cystic fibrosis transmembrane conductance regulator (CFTR) mutation are grown at reduced temperatures, the mutant protein can be properly processed. The effect of low temperatures on Cl^- channel activity in airway epithelial cells that endogenously express the ΔF508-CFTR mutation has not been investigated. Therefore, we examined the effect of incubation temperature on both CFTR and outwardly rectifying Cl^- channel (ORCC) activity in normal, in cystic fibrosis (CF)-affected, and in wild-type CFTR-complemented CF airway epithelia with use of a combination of inside-out and whole cell patch-clamp recording, ³⁶Cl^-efflux assays, and immunocytochemistry. We report that incubation of CF-affected airway epithelial cells at 25-27°C is associated with the appearance of a protein kinase A-stimulated CFTR-like Cl^- conductance. In addition to the appearance of CFTR Cl^- channel activity, there is, however, a decrease in the number of active ORCC when cells are grown at 25-27°C, suggesting that the decrease in incubation temperature may be associated with multiple alterations in ion channel expression and/or regulation in airway epithelial cells.