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

Tina Liu, Herman Bihler, Carlos M. Farinha, Nikhil T Awatade, Ana M Romão, Dayna Mercadante, Yi Cheng, Isaac Musisi, Walailak Jantarajit, Caroline Wang, Zhiwei Cai, Margarida D Amaral, Martin Mense, David N Sheppard*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)
325 Downloads (Pure)

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.
Original languageEnglish
Pages (from-to)1017-1038
Number of pages22
JournalBritish Journal of Pharmacology
Volume175
Issue number7
Early online date22 Feb 2018
DOIs
Publication statusPublished - 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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