The dF508 mutation represents the most common cause underlying cystic fibrosis. The resultant misfolding of the nascent cystic fibrosis transmembrane regulator (CFTR) protein and its subsequent proteasomal degradation lead to a deficiency in functional CFTR channels and Cl- efflux at the apical cell membrane in ducts throughout the body (Veit et al. 2016). Small molecule drugs have been identified that rectify this protein misfolding (‘correctors’) and facilitate channel opening (‘potentiators’), thereby restoring CFTR-mediated Cl- efflux at the apical cell membrane and providing clinical improvement (Hanrahan et al. 2017).
Nevertheless, enhanced efficacy remains a key research goal, and evidence indicates that this could be achieved by combining correctors/potentiators with modulators of the ubiquitin proteasomal system (UPS) that regulates CFTR protein degradation (Borgo et al. 2022). There is growing interest in the development of novel treatments that utilise this dual-target approach; we therefore set out to demonstrate that we could:
- Measure currents elicited by wild-type (WT) CFTR in transiently transfected
CHO-K1 cells using automated patch clamp (APC) electrophysiology. - Use the APC platform to confirm efficacy of CFTR correctors (VX-809,
VX-445/VX-661) and a potentiator (VX-770) in CHO-K1 cells transiently
transfected with dF508 CFTR. - Develop a 384-well halide-sensitive YFP assay for assessment of corrector
efficacy in HEK293 cells transiently transfected with dF508 CFTR. - Use the YFP assay to determine if modulators of the UPS (bortezomib, TAK-243)
enhance the efficacy of the CFTR corrector VX-809.
