Figure 1.

Protein trafficking and electrophysiological assays reveal increased correction of F508del-CFTR by a combination of VX-809 + RDR1. (A) Increase in F508del-CFTR protein at the cells surface upon treatment. BHK cells were preincubated with vehicle or RDR1, RDR3 (both 10 μM) and/or VX-661, VX-809 (both 1 μM) for 24 h in the CSEA assay. Results are relative to wild-type surface CFTR (100%). (B) Immunoblot of F508del-CFTR in BHK cells after 24-h treatment with RDR1 (10 μM) alone, VX-809 (1 μM) alone, or both and with wild-type CFTR (WT) as a control. (C) Relative intensity of bands B and band C in each lane in panel B. (D) F508del-CFTR functional expression in well-differentiated primary human bronchial epithelial (HBE) cells determined from the increase in short-circuit current stimulated by acute addition of forskolin + genistein (Δ Isc). The basolateral membrane was permeabilized using nystatin and an apical-to-basolateral chloride gradient was imposed. Representative I_sc responses of primary HBE cells expressing F508del-CFTR to sequential addition of 10 µM amiloride, 10 µM forskolin, 50 µM genistein, and 10 µM CFTRinh-172 after 24 h preincubation with 0.1% dimethylsulfoxide (vehicle), RDR1 (10 µM) or VX-809 (1 μM) individually and in combination. Data in panels A,C, and D are present as means ± SEM, n = 4, *p < 0.05.