Two Small Molecules Restore Stability to a Sub-population of the Cystic Fibrosis Transmembrane conductance Regulator with the Predominant Disease-causing Mutation

Xin Meng, Yiting Wang, Xiaomeng Wang, Joe Wrennall, Tracy Rimington, Hongyu Li, Zhiwei Cai, Robert C Ford, David Sheppard

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

26 Citations (Scopus)
326 Downloads (Pure)

Abstract

Cystic fibrosis (CF) is caused by mutations that disrupt the plasma membrane
expression, stability, and function of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Two small molecules, the CFTR corrector lumacaftor and the potentiator ivacaftor, are now used clinically to treat CF, although some studies suggest that they have counteracting effects on CFTR stability. Here, we investigated the impact of these compounds on the instability of F508del-CFTR, the most common CF mutation. To study individual CFTR Cl- channels, we performed single-channel recording, whereas to assess entire CFTR populations, we used purified CFTR proteins and macroscopic CFTR Cl- currents. At 37 °C, low temperature–rescued F508del-CFTR more rapidly lost function in cell-free membrane patches, and showed altered channel gating and
current flow through open channels. Compared with purified wild-type CFTR, the full-length F508del-CFTR was about 10 °C less thermostable. Lumacaftor partially stabilized purified full-length F508del-CFTR and slightly delayed deactivation of individual F508del-CFTR Clchannels. By contrast, ivacaftor further destabilized full-length F508del-CFTR and accelerated channel deactivation. Chronic (prolonged) co-incubation of F508del-CFTR– expressing cells with lumacaftor and ivacaftor deactivated macroscopic F508del-CFTR Cl-currents. However, at the single-channel level, chronic co-incubation greatly increased F508del-CFTR channel activity and temporal stability in most, but not all, cell-free membrane patches. We conclude that chronic lumacaftor and
ivacaftor co-treatment restores stability in a small sub-population of F508del-CFTR Clchannels, but that the majority remain destabilized. The fuller understanding of these effects and the characterization of the small F508del-CFTR subpopulation might be crucial for CF therapy development.
Original languageEnglish
Pages (from-to)3706-3719
Number of pages14
JournalJournal of Biological Chemistry
Volume292
Issue number9
DOIs
Publication statusPublished - 3 Mar 2017

Bibliographical note

13 January 2017

Keywords

  • ABC transporter
  • chloride channel
  • cystic fibrosis
  • cystic fibrosis transmembrane conductance regulator (CFTR)
  • protein purification
  • F508del-CFTR
  • G551D-CFTR
  • ivacaftor (VX- 770)
  • lumacaftor (VX-809)
  • thermal stability

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