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Updated: May 26, 2026
09:59
Functional Reconstitution and Channel Activity Measurements of Purified Wildtype and Mutant CFTR Protein
Published on: March 9, 2015
CFTR and TMEM16A are separate but functionally related Cl- channels
Jiraporn Ousingsawat1, Patthara Kongsuphol, Rainer Schreiber
1Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg, Germany.
Summary
The cystic fibrosis transmembrane conductance regulator (CFTR) functionally interacts with TMEM16A, a key component of calcium-activated chloride channels (CaCC). Activating CFTR inhibits CaCC activity, suggesting a regulatory relationship between these ion channels in airway epithelial cells.
Area of Science:
- Cellular Biology
- Ion Channel Physiology
- Molecular Medicine
Background:
- The cystic fibrosis transmembrane conductance regulator (CFTR) is crucial for epithelial ion transport.
- Calcium-activated chloride channels (CaCC) play a significant role in regulating cellular chloride secretion.
- TMEM16A has been identified as a primary component of CaCC.
Purpose of the Study:
- To investigate the functional relationship between CFTR and TMEM16A.
- To determine if CFTR regulates the activity of TMEM16A-mediated CaCC.
- To explore the molecular interactions between CFTR and TMEM16A.
Main Methods:
- Electrophysiological recordings (whole-cell currents) in human airway epithelial cells (16HBE, CFBE) and HEK293 cells.
- Pharmacological manipulation using activators (forskolin, IBMX) and inhibitors (CaCCinh-A01, niflumic acid, CFTRinh-172).
- Co-immunoprecipitation and cell surface localization studies to assess protein interactions.
Main Results:
- Endogenous CaCC activity was inhibited by CFTR activation in 16HBE cells.
- Overexpression and activation of CFTR inhibited CaCC in CFBE cells lacking endogenous CFTR.
- Co-expression of CFTR and TMEM16A attenuated currents from both channels, and they were found to be co-immunoprecipitated, indicating a physical and functional interaction.
Conclusions:
- CFTR and TMEM16A represent distinct molecular entities with significant functional and molecular interactions.
- CFTR can modulate TMEM16A-dependent CaCC activity, suggesting a coordinated role in epithelial ion transport.
- These findings provide new insights into the complex regulation of ion channel function in airway epithelia.
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