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Publication - Professor David Sheppard

    Partial rescue of F508del-cystic fibrosis transmembrane conductance regulator channel gating with modest improvement of protein processing, but not stability, by a dual-acting small molecule

    Citation

    Liu, T, Bihler, H, Farinha, CM, Awatade, NT, Romão, AM, Mercadante, D, Cheng, Y, Musisi, I, Jantarajit, W, Wang, C, Cai, Z, Amaral, MD, Mense, M & Sheppard, DN, 2018, ‘Partial rescue of F508del-cystic fibrosis transmembrane conductance regulator channel gating with modest improvement of protein processing, but not stability, by a dual-acting small molecule’. British Journal of Pharmacology, vol 175., pp. 1017-1038

    Abstract

    Background and purpose. Rescue of F508del-cystic fibrosis transmembrane conductance regulator (CFTR), the most common cystic fibrosis (CF) mutation, requires small molecules that overcome protein processing, stability and channel gating defects. Here, we investigate F508del-CFTR rescue by CFFT-004 (from WO2010/068863), a small molecule designed to independently correct protein processing and channel gating defects.

    Experimental approach. Using CFTR-expressing recombinant cells and CF patient-derived bronchial epithelial cells, we studied CFTR expression by Western blotting and channel gating and stability with the patch-clamp and Ussing chamber techniques.

    Key results. Chronic treatment with CFFT-004 improved modestly F508del-CFTR processing, but not its plasma membrane stability. By contrast, CFFT-004 rescued F508del-CFTR channel gating better than C18, an analogue of the clinically-used CFTR corrector lumacaftor. Subsequent acute addition of CFFT-004, but not C18, potentiated F508del-CFTR channel gating. However, CFFT-004 was without effect on A561E-CFTR, a CF mutation with a comparable mechanism of CFTR dysfunction as F508del-CFTR. To investigate the mechanism of action of CFFT-004, we used F508del-CFTR revertant mutations. Potentiation by CFFT-004 was unaffected by revertant mutations, but correction was abolished by the revertant mutation G550E. These data suggest that correction, but not potentiation by CFFT-004 might involve nucleotide-binding domain 1 of CFTR.

    Conclusions and implications. CFFT-004 is a dual-acting small molecule with independent corrector and potentiator activities that partially rescues F508del-CFTR in recombinant cells and native airway epithelia. The limited efficacy and potency of CFFT-004 suggests that combinations of small molecules targeting different defects in F508del-CFTR might be a more effective therapeutic strategy than a single agent.

    Full details in the University publications repository