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ORIGINAL RESEARCH article

Front. Pharmacol.

Sec. Pharmacology of Ion Channels and Channelopathies

Volume 16 - 2025 | doi: 10.3389/fphar.2025.1655479

This article is part of the Research TopicEpithelial Transport: from fluid movement toward system organizationView all 4 articles

CFTR Ion Transport Deficiency Primes the Epithelium for Partial Epithelial-Mesenchymal Transition in Cystic Fibrosis

Provisionally accepted
Cláudia  S RodriguesCláudia S RodriguesMatilde  CantoMatilde CantoRaquel  TorresRaquel TorresVioleta  RaileanVioleta RaileanSofia  S RamalhoSofia S RamalhoCarlos  M FarinhaCarlos M FarinhaInes  PankonienInes Pankonien*Margarida  D AmaralMargarida D Amaral*
  • Universidade de Lisboa Instituto de Biossistemas e Ciencias Integrativas, Lisbon, Portugal

The final, formatted version of the article will be published soon.

Cystic fibrosis (CF) is a monogenic disease caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene, which encodes a Cl-/HCO3- ion channel located at the apical plasma membrane (PM) of epithelial cells. CFTR dysfunction disrupts epithelial barrier integrity, drives progressive airway remodelling and has been associated with epithelial-to-mesenchymal transition (EMT), a process in which cells lose epithelial properties and acquire mesenchymal characteristics. We previously demonstrated that mutant CFTR directly drives partial EMT, independently of bacterial infection or inflammation. Here, we investigated whether PM localisation of CFTR alone is sufficient to preserve epithelial integrity or if its ion transport function is also required using polarized CF bronchial epithelial (CFBE) cells expressing wt-, p.Phe508del-, or p.Gly551Asp-CFTR. While p.Phe508del-CFTR is retained in the endoplasmic reticulum (ER) and fails to traffic to the PM, p.Gly551Asp-CFTR reaches the PM but lacks ion transport function. The degree of mesenchymal phenotype was higher in cells expressing p.Phe508del-CFTR vs those expressing PM localized but non-functional p.Gly551Asp-CFTR. This was evidenced by lower transepithelial electrical resistance (TEER), higher expression of mesenchymal markers (N-cadherin, vimentin), and lower E-/N-cadherin ratio. Furthermore, both CF cells displayed delayed wound healing compared to wt-CFTR cells, while only p.Phe508del-CFTR cells, but not p.Gly551Asp-CFTR, showed increased cell proliferation. Moreover, treatment with CFTR modulators (CFTRm) partially restored tight junction integrity by increasing claudin-1 levels and E-/N-cadherin ratio in both mutant cells. TGF-β1 treatment induced EMT in all three cell lines by decreasing epithelial markers (E-cadherin, cytokeratin 18, claudin-1) while increasing N-cadherin levels. However, mesenchymal marker vimentin increased only in CF cells, and more prominently in p.Phe508del-CFTR than in p.Gly551Asp-CFTR cells. Additionally, CFTR inhibition in wt-CFTR cells, partially mimicked p.Gly551Asp-CFTR behaviour, i.e., reduced claudin-1 levels. Altogether, these findings demonstrate that the loss of CFTR ion transport, despite the physical presence of (nonfunctional) CFTR at the PM, is enough to trigger partial EMT. However, the severity of the EMT phenotype worsens when CFTR is absent from the PM while also increasing susceptibility to TGF-β1- triggered EMT. Moreover, CFTRm only partially reverse this CF EMT state, indicating that full epithelial integrity will likely require targeting additional factors.

Keywords: Cystic Fibrosis, CFTR, P.Phe508del, p.Gly551Asp, Epithelial-Mesenchymal Transition

Received: 27 Jun 2025; Accepted: 05 Aug 2025.

Copyright: © 2025 Rodrigues, Canto, Torres, Railean, Ramalho, Farinha, Pankonien and Amaral. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Ines Pankonien, Universidade de Lisboa Instituto de Biossistemas e Ciencias Integrativas, Lisbon, Portugal
Margarida D Amaral, Universidade de Lisboa Instituto de Biossistemas e Ciencias Integrativas, Lisbon, Portugal

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