The CFTR plays a crucial regulatory role in ion/fluid homeostasis essential to lung health, impacting both anion (directly) and cation (indirectly) transport. The complexity of CFTR function requires a complex and dynamic structure that has evolved relatively recently as a unique ABC transporter family member. Like all proteins, CFTR evolution had to achieve a balance between structural complexity and thermodynamic stability with the result that only ~25% of wild-type polypeptide chains synthesized achieve a stable state. The AF508 mutation exacerbates inefficient biogenesis, reducing this proportion to essentially zero. Some manipulations including reduced temperature, down-regulation of quality control components and so-called """"""""corrector"""""""" small molecules improve cellular processing and trafficking. However, these maneuvers do not restore Thermal Stability (TS) and the partial channel function at temperatures <30oC is rapidly lost at 37oC. Thus effective therapies require reagents that restore TS. Here we focus on the allosteric coupling pathways that determine TS to understand its mechanistic basis so that it can be manipulated rationally. SA 1 will elucidate the destabilizing influence of the Regulatory Insertion (Rl) in NBD1 and how its excision restores stability and function. SA 2 will employ two complementary approaches to identify other changes that restoreTS, the first utilizing molecular dynamics and the second exploring the basis of retained TS by AF508 CFTRs of some other species that are stable. These methods have already revealed that the introduction of proline residues at key positions in coupling pathways stabilize AF508 CFTR. SA 3 will utilize both small and larger molecule binders of CFTR as thermal stabilizers. First, small molecule libraries will be screened computationally (validated experimentally) for binding to regions of the protein implicated in TS. Second, we will identify larger protein/peptide binders including synthetic antibodies and nanobodies. Effective initial reagents have already been developed in collaboration with leading laboratories in both fields. In addition to providing an entirely new paradigm with integrated computational and experimental approaches to the CF problem, we provide the other projects of this PPG with essential CFTR tools and methodologies.

Public Health Relevance

The proposed studies are specifically relevant to cystic fibrosis as they focus on a here-to-for neglected fundamental aspect of the molecular defect. As CFTR is also sensitive to environmental insults of the lung that contribute to COPD, the project is also relevant to that major health problem. Even more broadly, CFTR is also important in the functioning of the intestinal and reproductive tracts and other tissues such as the sweat gland, important in body temperature control.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Program Projects (P01)
Project #
Application #
Study Section
Heart, Lung, and Blood Initial Review Group (HLBP)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of North Carolina Chapel Hill
Chapel Hill
United States
Zip Code
Abdullah, Lubna H; Coakley, Raymond; Webster, Megan J et al. (2018) Mucin Production and Hydration Responses to Mucopurulent Materials in Normal versus Cystic Fibrosis Airway Epithelia. Am J Respir Crit Care Med 197:481-491
Yu, Dongfang; Saini, Yogesh; Chen, Gang et al. (2018) Loss of ? Epithelial Sodium Channel Function in Meibomian Glands Produces Pseudohypoaldosteronism 1-Like Ocular Disease in Mice. Am J Pathol 188:95-110
Rowson-Hodel, A R; Wald, J H; Hatakeyama, J et al. (2018) Membrane Mucin Muc4 promotes blood cell association with tumor cells and mediates efficient metastasis in a mouse model of breast cancer. Oncogene 37:197-207
Terryah, Shawn T; Fellner, Robert C; Ahmad, Saira et al. (2018) Evaluation of a SPLUNC1-derived peptide for the treatment of cystic fibrosis lung disease. Am J Physiol Lung Cell Mol Physiol 314:L192-L205
Muhlebach, Marianne S; Zorn, Bryan T; Esther, Charles R et al. (2018) Initial acquisition and succession of the cystic fibrosis lung microbiome is associated with disease progression in infants and preschool children. PLoS Pathog 14:e1006798
Shobair, Mahmoud; Popov, Konstantin I; Dang, Yan L et al. (2018) Mapping allosteric linkage to channel gating by extracellular domains in the human epithelial sodium channel. J Biol Chem 293:3675-3684
Kota, Pradeep; Gentzsch, Martina; Dang, Yan L et al. (2018) The N terminus of ?-ENaC mediates ENaC cleavage and activation by furin. J Gen Physiol 150:1179-1187
Livraghi-Butrico, Alessandra; Wilkinson, Kristen J; Volmer, Allison S et al. (2018) Lung disease phenotypes caused by overexpression of combinations of ?-, ?-, and ?-subunits of the epithelial sodium channel in mouse airways. Am J Physiol Lung Cell Mol Physiol 314:L318-L331
Chen, Gang; Volmer, Allison S; Wilkinson, Kristen J et al. (2018) Role of Spdef in the Regulation of Muc5b Expression in the Airways of Naive and Mucoobstructed Mice. Am J Respir Cell Mol Biol 59:383-396
Livraghi-Butrico, A; Grubb, B R; Wilkinson, K J et al. (2017) Contribution of mucus concentration and secreted mucins Muc5ac and Muc5b to the pathogenesis of muco-obstructive lung disease. Mucosal Immunol 10:829

Showing the most recent 10 out of 56 publications