Effect of VX-770 (Ivacaftor) and OAG on Ca2+ influx and CFTR activity in G551D and F508del-CFTR expressing cells.

Abstract: Background: TRPC6 has been proposed to be responsible for the abnormal OAG-dependent Ca2+ influx in cystic fibrosis (CF) cells and we hypothesized that it interacts with CFTR. Here, we investigated how this functional complex operates in CF and non-CF epithelial cells. Methods: Chinese hamster ovary (CHO) cells stably transfected with pNut vector containing wild type CFTR (CHO-WT), F508del-CFTR (CHO-F508del) or G551D-CFTR(CHO-G551D) were used. Calcium channel activity was recorded using Fluo-4 probe and CFTR activity was measured by iodide efflux technique in the presence of CFTR activators (forskolin, genistein) and VX-770, CFTR inhibitor (GPinh5a) and TRPC non-selective modulators (OAG, SKF96365). Results: CFTR down regulates OAG Ca2+ response and OAG Ca2+ influx increases CFTR chloride efflux. Furthermore, we observed potentiation of G551D-CFTR activity when combining VX-770 and OAG. Conclusion: Taking advantage of the functional coupling between OAG-dependent Ca2+ influx and CFTR, a combination of OAG and VX-770 could be a therapeutic strategy for homozygote patients bearing the G551D-CFTR mutation. [Copyright &y& Elsevier]