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.
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.
Original language | English |
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Pages (from-to) | 1017-1038 |
Number of pages | 22 |
Journal | British Journal of Pharmacology |
Volume | 175 |
Issue number | 7 |
Early online date | 22 Feb 2018 |
DOIs | |
Publication status | Published - Apr 2018 |
Keywords
- ATP-binding cassette transporter
- CFTR
- chloride ion channel
- cystic fibrosis
- F508del-CFTR
- CFTR processing
- channel gating
- stability
- revertant mutations
- CFTR corrector-potentiator (dual-acting small molecule)
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Professor David N Sheppard
- School of Physiology, Pharmacology & Neuroscience - Professor of Physiology
- Dynamic Cell Biology
Person: Academic , Member