Figure 1.

Assessment of CFTR maturation of rare CFTR mutants and their response to corrector VX-809. (A) Schematic CFTR protein structure adapted from reference [21], depicting the (rare) CFTR mutants studied and the localization of the 3HA tag in the fourth extracellular loop [17]. Western blot analysis of (B) untagged and (C) 3HA-tagged CFTR variants by anti-CFTR antibodies and α-tubulin (loading control) in whole-cell lysates of stably transduced HEK293T cells. The lower band (‘band B’) represents immature, core-glycosylated CFTR, the upper band (‘band C’) the complex glycosylated, fully mature protein. (D) Rescue in CFTR maturation (without tag) by corrector VX-809 (2.5 µM, 24 h) expressed as the increase in band C over total (B + C) CFTR relative to WT. Dots (DMSO) and squares (VX-809) represent independent experiments, one of which is shown in (B). (E) Pearson correlation of the rescue in CFTR maturation by corrector VX-809 of untagged and 3HA-tagged CFTR variants, as quantified in (D). Graphs depict the mean ± S.D. of three (3HA−tagged) or four (untagged) independent experiments. VX-809 rescue over DMSO was compared for each mutant by multiple t-testing. ** P < 0.01, *** P < 0.001. ER: endoplasmic reticulum, 3HA: triple hemagglutinin, ECL: extracellular loop, IL: intracellular loop, NBD: nucleotide binding domain, MSD: membrane spanning domain, R: regulatory domain, LV: lentiviral vector.