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Ferreira FC, Buarque CD, Lopes-Pacheco M. Organic Synthesis and Current Understanding of the Mechanisms of CFTR Modulator Drugs Ivacaftor, Tezacaftor, and Elexacaftor. Molecules 2024; 29:821. [PMID: 38398574 PMCID: PMC10891718 DOI: 10.3390/molecules29040821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
The monogenic rare disease Cystic Fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance (CFTR) protein, an anion channel expressed at the apical plasma membrane of epithelial cells. The discovery and subsequent development of CFTR modulators-small molecules acting on the basic molecular defect in CF-have revolutionized the standard of care for people with CF (PwCF), thus drastically improving their clinical features, prognosis, and quality of life. Currently, four of these drugs are approved for clinical use: potentiator ivacaftor (VX-770) alone or in combination with correctors lumacaftor, (VX-809), tezacaftor (VX-661), and elexacaftor (VX-445). Noteworthily, the triple combinatorial therapy composed of ivacaftor, tezacaftor, and elexacaftor constitutes the most effective modulator therapy nowadays for the majority of PwCF. In this review, we exploit the organic synthesis of ivacaftor, tezacaftor, and elexacaftor by providing a retrosynthetic drug analysis for these CFTR modulators. Furthermore, we describe the current understanding of the mechanisms of action (MoA's) of these compounds by discussing several studies that report the key findings on the molecular mechanisms underlying their action on the CFTR protein.
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Affiliation(s)
- Filipa C. Ferreira
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Camilla D. Buarque
- Department of Chemistry, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Rio de Janeiro 22435-900, RJ, Brazil
| | - Miquéias Lopes-Pacheco
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
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2
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Yeh HI, Sutcliffe KJ, Sheppard DN, Hwang TC. CFTR Modulators: From Mechanism to Targeted Therapeutics. Handb Exp Pharmacol 2024; 283:219-247. [PMID: 35972584 DOI: 10.1007/164_2022_597] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
People with cystic fibrosis (CF) suffer from a multi-organ disorder caused by loss-of-function variants in the gene encoding the epithelial anion channel cystic fibrosis transmembrane conductance regulator (CFTR). Tremendous progress has been made in both basic and clinical sciences over the past three decades since the identification of the CFTR gene. Over 90% of people with CF now have access to therapies targeting dysfunctional CFTR. This success was made possible by numerous studies in the field that incrementally paved the way for the development of small molecules known as CFTR modulators. The advent of CFTR modulators transformed this life-threatening illness into a treatable disease by directly binding to the CFTR protein and correcting defects induced by pathogenic variants. In this chapter, we trace the trajectory of structural and functional studies that brought CF therapies from bench to bedside, with an emphasis on mechanistic understanding of CFTR modulators.
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Affiliation(s)
- Han-I Yeh
- Department of Pharmacology, National Yang Ming Chiao Tung University, Taipei City, Taiwan
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Katy J Sutcliffe
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Tzyh-Chang Hwang
- Department of Pharmacology, National Yang Ming Chiao Tung University, Taipei City, Taiwan.
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA.
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA.
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3
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Simon MA, Iordanov I, Szollosi A, Csanády L. Estimating the true stability of the prehydrolytic outward-facing state in an ABC protein. eLife 2023; 12:e90736. [PMID: 37782012 PMCID: PMC10569789 DOI: 10.7554/elife.90736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/01/2023] [Indexed: 10/03/2023] Open
Abstract
CFTR, the anion channel mutated in cystic fibrosis patients, is a model ABC protein whose ATP-driven conformational cycle is observable at single-molecule level in patch-clamp recordings. Bursts of CFTR pore openings are coupled to tight dimerization of its two nucleotide-binding domains (NBDs) and in wild-type (WT) channels are mostly terminated by ATP hydrolysis. The slow rate of non-hydrolytic closure - which determines how tightly bursts and ATP hydrolysis are coupled - is unknown, as burst durations of catalytic site mutants span a range of ~200-fold. Here, we show that Walker A mutation K1250A, Walker B mutation D1370N, and catalytic glutamate mutations E1371S and E1371Q all completely disrupt ATP hydrolysis. True non-hydrolytic closing rate of WT CFTR approximates that of K1250A and E1371S. That rate is slowed ~15-fold in E1371Q by a non-native inter-NBD H-bond, and accelerated ~15-fold in D1370N. These findings uncover unique features of the NBD interface in human CFTR.
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Affiliation(s)
- Márton A Simon
- Department of Biochemistry, Semmelweis UniversityBudapestHungary
- HCEMM-SE Molecular Channelopathies Research GroupBudapestHungary
- HUN-REN-SE Ion Channel Research GroupBudapestHungary
| | - Iordan Iordanov
- Department of Biochemistry, Semmelweis UniversityBudapestHungary
- HCEMM-SE Molecular Channelopathies Research GroupBudapestHungary
- HUN-REN-SE Ion Channel Research GroupBudapestHungary
| | - Andras Szollosi
- Department of Biochemistry, Semmelweis UniversityBudapestHungary
- HCEMM-SE Molecular Channelopathies Research GroupBudapestHungary
- HUN-REN-SE Ion Channel Research GroupBudapestHungary
| | - László Csanády
- Department of Biochemistry, Semmelweis UniversityBudapestHungary
- HCEMM-SE Molecular Channelopathies Research GroupBudapestHungary
- HUN-REN-SE Ion Channel Research GroupBudapestHungary
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4
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Hwang TC, Braakman I, van der Sluijs P, Callebaut I. Structure basis of CFTR folding, function and pharmacology. J Cyst Fibros 2023; 22 Suppl 1:S5-S11. [PMID: 36216744 DOI: 10.1016/j.jcf.2022.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/19/2022] [Accepted: 09/26/2022] [Indexed: 11/05/2022]
Abstract
The root cause of cystic fibrosis (CF), the most common life-shortening genetic disease in the Caucasian population, is the loss of function of the CFTR protein, which serves as a phosphorylation-activated, ATP-gated anion channel in numerous epithelia-lining tissues. In the past decade, high-throughput drug screening has made a significant stride in developing highly effective CFTR modulators for the treatment of CF. Meanwhile, structural-biology studies have succeeded in solving the high-resolution three-dimensional (3D) structure of CFTR in different conformations. Here, we provide a brief overview of some striking features of CFTR folding, function and pharmacology, in light of its specific structural features within the ABC-transporter superfamily. A particular focus is given to CFTR's first nucleotide-binding domain (NBD1), because folding of NBD1 constitutes a bottleneck in the CFTR protein biogenesis pathway, and ATP binding to this domain plays a unique role in the functional stability of CFTR. Unraveling the molecular basis of CFTR folding, function, and pharmacology would inspire the development of next-generation mutation-specific CFTR modulators.
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Affiliation(s)
- Tzyh-Chang Hwang
- Institute of Pharmacology, School of Medicine, National Yang Ming Chiao Tung University, Taiwan; Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Ineke Braakman
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Peter van der Sluijs
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France.
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5
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Fang X, Yeh JT, Hwang TC. Pharmacological Responses of the G542X-CFTR to CFTR Modulators. Front Mol Biosci 2022; 9:921680. [PMID: 35813815 PMCID: PMC9263564 DOI: 10.3389/fmolb.2022.921680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Cystic fibrosis (CF) is a lethal hereditary disease caused by loss-of-function mutations of the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR). With the development of small-molecule CFTR modulators, including correctors that facilitate protein folding and expression and potentiators that promote channel activity, about 90% of the CF patients are now receiving efficacious target therapies. G542X-CFTR, a premature termination codon (PTC) mutation, is the most common disease-associated mutation found in the remaining 10% of patients that await effective drugs to rectify the fundamental defects caused by PTC. In this study, we employed biophysical and biochemical techniques to characterize the pharmacological responses of the translational products of G542X-CFTR to a range of new CFTR modulators. Specifically, we identified two different proteins translated from the G542X-CFTR cDNA using western blotting: the C-terminus truncated protein that responds to the C1 corrector which binds to the N-terminal part of the protein and a full-length CFTR protein through the read-through process. Electrophysiological data suggest that the read-through protein, but not the C-terminus truncated one, is functional and responds well to CFTR potentiators despite a lower open probability compared to wild-type CFTR. As the expression of the read-through products can be increased synergistically with the read-through reagent G418 and C1 corrector, but not with combinations of different types of correctors, we concluded that an efficacious read-through reagent is a prerequisite for mitigating the deficits of G542X-CFTR. Moreover, the CFTR potentiators may help improve the effectiveness of future combinational therapy for patients carrying PTCs such as G542X.
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Affiliation(s)
- Xinxiu Fang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
| | - Jiunn-Tyng Yeh
- School of Medicine, National Yang Ming Chiao Tung University College of Medicine, Taipei, Taiwan
- *Correspondence: Jiunn-Tyng Yeh,
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
- Department of Pharmacology, National Yang Ming Chiao Tung University College of Medicine, Taipei, Taiwan
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6
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Ensinck MM, Carlon MS. One Size Does Not Fit All: The Past, Present and Future of Cystic Fibrosis Causal Therapies. Cells 2022; 11:cells11121868. [PMID: 35740997 PMCID: PMC9220995 DOI: 10.3390/cells11121868] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 05/25/2022] [Accepted: 05/28/2022] [Indexed: 02/04/2023] Open
Abstract
Cystic fibrosis (CF) is the most common monogenic disorder, caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Over the last 30 years, tremendous progress has been made in understanding the molecular basis of CF and the development of treatments that target the underlying defects in CF. Currently, a highly effective CFTR modulator treatment (Kalydeco™/Trikafta™) is available for 90% of people with CF. In this review, we will give an extensive overview of past and ongoing efforts in the development of therapies targeting the molecular defects in CF. We will discuss strategies targeting the CFTR protein (i.e., CFTR modulators such as correctors and potentiators), its cellular environment (i.e., proteostasis modulation, stabilization at the plasma membrane), the CFTR mRNA (i.e., amplifiers, nonsense mediated mRNA decay suppressors, translational readthrough inducing drugs) or the CFTR gene (gene therapies). Finally, we will focus on how these efforts can be applied to the 15% of people with CF for whom no causal therapy is available yet.
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Affiliation(s)
- Marjolein M. Ensinck
- Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Flanders, Belgium;
| | - Marianne S. Carlon
- Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Flanders, Belgium;
- Laboratory of Respiratory Diseases and Thoracic Surgery (BREATHE), Department of Chronic Diseases and Metabolism, KU Leuven, 3000 Leuven, Flanders, Belgium
- Correspondence:
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7
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Infield DT, Strickland KM, Gaggar A, McCarty NA. The molecular evolution of function in the CFTR chloride channel. J Gen Physiol 2021; 153:212705. [PMID: 34647973 PMCID: PMC8640958 DOI: 10.1085/jgp.202012625] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/11/2021] [Accepted: 09/09/2021] [Indexed: 12/13/2022] Open
Abstract
The ATP-binding cassette (ABC) transporter superfamily includes many proteins of clinical relevance, with genes expressed in all domains of life. Although most members use the energy of ATP binding and hydrolysis to accomplish the active import or export of various substrates across membranes, the cystic fibrosis transmembrane conductance regulator (CFTR) is the only known animal ABC transporter that functions primarily as an ion channel. Defects in CFTR, which is closely related to ABCC subfamily members that bear function as bona fide transporters, underlie the lethal genetic disease cystic fibrosis. This article seeks to integrate structural, functional, and genomic data to begin to answer the critical question of how the function of CFTR evolved to exhibit regulated channel activity. We highlight several examples wherein preexisting features in ABCC transporters were functionally leveraged as is, or altered by molecular evolution, to ultimately support channel function. This includes features that may underlie (1) construction of an anionic channel pore from an anionic substrate transport pathway, (2) establishment and tuning of phosphoregulation, and (3) optimization of channel function by specialized ligand–channel interactions. We also discuss how divergence and conservation may help elucidate the pharmacology of important CFTR modulators.
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Affiliation(s)
- Daniel T Infield
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | | | - Amit Gaggar
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL.,Program in Protease and Matrix Biology, University of Alabama at Birmingham, Birmingham, AL.,Birmingham Veterans Administration Medical Center, Birmingham, AL
| | - Nael A McCarty
- Department of Pediatrics, Emory University, Atlanta, GA.,Children's Healthcare of Atlanta Center for Cystic Fibrosis and Airways Disease Research, Emory University, Atlanta, GA
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8
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Laselva O, Qureshi Z, Zeng ZW, Petrotchenko EV, Ramjeesingh M, Hamilton CM, Huan LJ, Borchers CH, Pomès R, Young R, Bear CE. Identification of binding sites for ivacaftor on the cystic fibrosis transmembrane conductance regulator. iScience 2021; 24:102542. [PMID: 34142049 PMCID: PMC8184517 DOI: 10.1016/j.isci.2021.102542] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/22/2021] [Accepted: 05/11/2021] [Indexed: 11/25/2022] Open
Abstract
Ivacaftor (VX-770) was the first cystic fibrosis transmembrane conductance regulator (CFTR) modulatory drug approved for the treatment of patients with cystic fibrosis. Electron cryomicroscopy (cryo-EM) studies of detergent-solubilized CFTR indicated that VX-770 bound to a site at the interface between solvent and a hinge region in the CFTR protein conferred by transmembrane (tm) helices: tm4, tm5, and tm8. We re-evaluated VX-770 binding to CFTR in biological membranes using photoactivatable VX-770 probes. One such probe covalently labeled CFTR at two sites as determined following trypsin digestion and analysis by tandem-mass spectrometry. One labeled peptide resides in the cytosolic loop 4 of CFTR and the other is located in tm8, proximal to the site identified by cryo-EM. Complementary data from functional and molecular dynamic simulation studies support a model, where VX-770 mediates potentiation via multiple sites in the CFTR protein.
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Affiliation(s)
- Onofrio Laselva
- Programme in Molecular Medicine, Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Zafar Qureshi
- Department of Chemistry, Simon Fraser University, Burnaby, Canada
| | - Zhi-Wei Zeng
- Programme in Molecular Medicine, Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Evgeniy V. Petrotchenko
- Segal Cancer Proteomics Center, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Canada
- Center for Computational and Data-Intensive Science and Engineering, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Mohabir Ramjeesingh
- Programme in Molecular Medicine, Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | | | - Ling-Jun Huan
- Programme in Molecular Medicine, Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Christoph H. Borchers
- Segal Cancer Proteomics Center, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Canada
- Center for Computational and Data-Intensive Science and Engineering, Skolkovo Institute of Science and Technology, Moscow 121205, Russia
- Gerald Bronfman Department of Oncology, Jewish General Hospital, McGill University, Montreal, Quebec H3T 1E2, Canada
| | - Régis Pomès
- Programme in Molecular Medicine, Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Robert Young
- Department of Chemistry, Simon Fraser University, Burnaby, Canada
| | - Christine E. Bear
- Programme in Molecular Medicine, Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Department of Physiology, University of Toronto, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
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9
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Silva IAL, Doušová T, Ramalho S, Centeio R, Clarke LA, Railean V, Botelho HM, Holubová A, Valášková I, Yeh JT, Hwang TC, Farinha CM, Kunzelmann K, Amaral MD. Organoids as a personalized medicine tool for ultra-rare mutations in cystic fibrosis: The case of S955P and 1717-2A>G. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165905. [PMID: 32730979 PMCID: PMC7484254 DOI: 10.1016/j.bbadis.2020.165905] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND For most of the >2000 CFTR gene variants reported, neither the associated disease liability nor the underlying basic defect are known, and yet these are essential for disease prognosis and CFTR-based therapeutics. Here we aimed to characterize two ultra-rare mutations - 1717-2A > G (c.1585-2A > G) and S955P (p.Ser955Pro) - as case studies for personalized medicine. METHODS Patient-derived rectal biopsies and intestinal organoids from two individuals with each of these mutations and F508del (p.Phe508del) in the other allele were used to assess CFTR function, response to modulators and RNA splicing pattern. In parallel, we used cellular models to further characterize S955P independently of F508del and to assess its response to CFTR modulators. RESULTS Results in both rectal biopsies and intestinal organoids from both patients evidence residual CFTR function. Further characterization shows that 1717-2A > G leads to alternative splicing generating <1% normal CFTR mRNA and that S955P affects CFTR gating. Finally, studies in organoids predict that both patients are responders to VX-770 alone and even more to VX-770 combined with VX-809 or VX-661, although to different levels. CONCLUSION This study demonstrates the high potential of personalized medicine through theranostics to extend the label of approved drugs to patients with rare mutations.
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Affiliation(s)
- Iris A L Silva
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Tereza Doušová
- Department of Pediatrics, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84,Prague 5, 150 06 Prague, Czech Republic
| | - Sofia Ramalho
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Raquel Centeio
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Luka A Clarke
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Violeta Railean
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Hugo M Botelho
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Andrea Holubová
- Department of Biology and Medical Genetics, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84,Prague 5, 150 06 Prague, Czech Republic
| | - Iveta Valášková
- Department of Medical Genetics, Masaryk University Brno and University Hospital Brno, Jihlavská 20, Brno 625 00, Czech Republic
| | - Jiunn-Tyng Yeh
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States of America
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States of America
| | - Carlos M Farinha
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal.
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10
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Froux L, Elbahnsi A, Boucherle B, Billet A, Baatallah N, Hoffmann B, Alliot J, Zelli R, Zeinyeh W, Haudecoeur R, Chevalier B, Fortuné A, Mirval S, Simard C, Lehn P, Mornon JP, Hinzpeter A, Becq F, Callebaut I, Décout JL. Targeting different binding sites in the CFTR structures allows to synergistically potentiate channel activity. Eur J Med Chem 2020; 190:112116. [DOI: 10.1016/j.ejmech.2020.112116] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 01/24/2020] [Accepted: 02/03/2020] [Indexed: 02/06/2023]
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11
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Yeh JT, Hwang TC. Positional effects of premature termination codons on the biochemical and biophysical properties of CFTR. J Physiol 2019; 598:517-541. [PMID: 31585024 DOI: 10.1113/jp278418] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/16/2019] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Biochemical and biophysical characterizations of three nonsense mutations of cystic fibrosis transmembrane conductance regulator (CFTR) associated with a severe form of cystic fibrosis (CF) reveal the importance and heterogenous effects of the position of the premature termination codon (PTC) on the CFTR protein function. Electrophysiological studies of W1282X-CFTR, whose PTC is closer to the C-terminus of CFTR, suggest the presence of both C-terminus truncated CFTR proteins that are poorly functional and read-through, full-length products. For G542X- and E60X-CFTR, the only mechanism capable of generating functional proteins is the read-through, but the outcome of read-through products is highly variable depending on the interplay between the missense mutation caused by the read-through and the structural context of the protein. Pharmacological studies of these three PTCs with various CFTR modulators suggest position-dependent therapeutic strategies for these disease-inflicting mutations. ABSTRACT About one-third of genetic diseases and cancers are caused by the introduction of premature termination codons (PTCs). In theory, the location of the PTC in a gene determines the alternative mechanisms of translation, including premature cessation or reinitiation of translation, and read-through, resulting in differential effects on protein integrity. In this study, we used CFTR as a model system to investigate the positional effect of the PTC because of its well-understood structure-function relationship and pathophysiology. The characterization of three PTC mutations, E60X-, G542X- and W1282X-CFTR revealed heterogenous effects of these PTCs on CFTR function. The W1282X mutation results in both C-terminus truncated and read-through proteins that are partially or fully functional. In contrast, only the read-through protein is functional with E60X- and G542X-CFTR, although abundant N-terminus truncated proteins due to reinitiation of translation were detected in E60X-CFTR. Single-channel studies of the read-through proteins of E60X- and G542X-CFTR demonstrated that both mutations have a single-channel amplitude similar to wild type (WT), and good responses to high-affinity ATP analogues, suggesting intact ion permeation pathways and nucleotide binding domains (NBDs), albeit with reduced open probability (Po ). The comparison of the Po of these mutations with the proposed missense mutations revealed potential identities of the read-through products. Importantly, a majority of the functional protein studied responds to CFTR modulators like GLPG1837 and Lumacaftor. These results not only expand current understanding of the molecular (patho)physiology of CFTR, but also infer therapeutic strategies for different PTC mutations at large.
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Affiliation(s)
- Jiunn-Tyng Yeh
- Interdisciplinary Neuroscience Program, University of Missouri, Columbia, MO, 65211, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, USA
| | - Tzyh-Chang Hwang
- Interdisciplinary Neuroscience Program, University of Missouri, Columbia, MO, 65211, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, 65211, USA.,Department of Pharmacology and Physiology, School of Medicine, University of Missouri, Columbia, MO, 65211, USA
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12
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Csanády L, Töröcsik B. Cystic fibrosis drug ivacaftor stimulates CFTR channels at picomolar concentrations. eLife 2019; 8:46450. [PMID: 31205003 PMCID: PMC6594753 DOI: 10.7554/elife.46450] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/14/2019] [Indexed: 02/07/2023] Open
Abstract
The devastating inherited disease cystic fibrosis (CF) is caused by mutations of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) anion channel. The recent approval of the CFTR potentiator drug ivacaftor (Vx-770) for the treatment of CF patients has marked the advent of causative CF therapy. Currently, thousands of patients are being treated with the drug, and its molecular mechanism of action is under intensive investigation. Here we determine the solubility profile and true stimulatory potency of Vx-770 towards wild-type (WT) and mutant human CFTR channels in cell-free patches of membrane. We find that its aqueous solubility is ~200 fold lower (~60 nanomolar), whereas the potency of its stimulatory effect is >100 fold higher, than reported, and is unexpectedly fully reversible. Strong, but greatly delayed, channel activation by picomolar Vx-770 identifies multiple sequential slow steps in the activation pathway. These findings provide solid guidelines for the design of in vitro studies using Vx-770.
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Affiliation(s)
- László Csanády
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.,MTA-SE Ion Channel Research Group, Semmelweis University, Budapest, Hungary
| | - Beáta Töröcsik
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.,MTA-SE Ion Channel Research Group, Semmelweis University, Budapest, Hungary
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13
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Yeh HI, Qiu L, Sohma Y, Conrath K, Zou X, Hwang TC. Identifying the molecular target sites for CFTR potentiators GLPG1837 and VX-770. J Gen Physiol 2019; 151:912-928. [PMID: 31164398 PMCID: PMC6605684 DOI: 10.1085/jgp.201912360] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/29/2019] [Accepted: 05/10/2019] [Indexed: 01/14/2023] Open
Abstract
Identification of the binding sites for small molecules that alleviate gating
defects in CFTR would assist rational drug design for the treatment of cystic
fibrosis. Yeh et al. identify two potential binding sites for prototypical CFTR
potentiators at the interface of CFTR’s two transmembrane domains. The past two decades have witnessed major breakthroughs in developing compounds
that target the chloride channel CFTR for the treatment of patients with cystic
fibrosis. However, further improvement in affinity and efficacy for these CFTR
modulators will require insights into the molecular interactions between CFTR
modulators and their binding targets. In this study, we use in silico molecular
docking to identify potential binding sites for GLPG1837, a CFTR potentiator
that may share a common mechanism and binding site with VX-770, the FDA-approved
drug for patients carrying mutations with gating defects. Among the five binding
sites predicted by docking, the two top-scoring sites are located at the
interface between CFTR’s two transmembrane domains: site I consists of
D924, N1138, and S1141, and site IIN includes F229, F236, Y304, F312,
and F931. Using mutagenesis to probe the importance of these sites for GLPG187
binding, we find that disruption of predicted hydrogen-bonding interactions by
mutation of D924 decreases apparent affinity, while hydrophobic amino acids
substitutions at N1138 and introduction of positively charged amino acids at
S1141 improve the apparent affinity for GLPG1837. Alanine substitutions at Y304,
F312, and F931 (site IIN) decrease the affinity for GLPG1837, whereas
alanine substitutions at F229 and F236 (also site IIN), or at
residues in the other three lower-scoring sites, have little effect. In
addition, current relaxation analysis to assess the apparent dissociation rate
of VX-770 yields results consistent with the dose–response experiments
for GLPG8137, with the dissociation rate of VX-770 accelerated by D924N, F236A,
Y304A, and F312A, but decelerated by N1138L and S1141K mutations. Collectively,
these data identify two potential binding sites for GLPG1837 and VX-770 in CFTR.
We discuss the pros and cons of evidence for these two loci and the implications
for future drug design.
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Affiliation(s)
- Han-I Yeh
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Liming Qiu
- Dalton Cardiovascular Research Center, Department of Physics and Astronomy, Department of Biochemistry, and Informatics Institute, University of Missouri, Columbia, MO
| | - Yoshiro Sohma
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO.,Department of Pharmaceutical Sciences, School of Pharmacy and Center for Medical Science, International University of Health and Welfare, Tochigi, Japan
| | | | - Xiaoqin Zou
- Dalton Cardiovascular Research Center, Department of Physics and Astronomy, Department of Biochemistry, and Informatics Institute, University of Missouri, Columbia, MO
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
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14
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Csanády L, Vergani P, Gadsby DC. STRUCTURE, GATING, AND REGULATION OF THE CFTR ANION CHANNEL. Physiol Rev 2019; 99:707-738. [PMID: 30516439 DOI: 10.1152/physrev.00007.2018] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) belongs to the ATP binding cassette (ABC) transporter superfamily but functions as an anion channel crucial for salt and water transport across epithelial cells. CFTR dysfunction, because of mutations, causes cystic fibrosis (CF). The anion-selective pore of the CFTR protein is formed by its two transmembrane domains (TMDs) and regulated by its cytosolic domains: two nucleotide binding domains (NBDs) and a regulatory (R) domain. Channel activation requires phosphorylation of the R domain by cAMP-dependent protein kinase (PKA), and pore opening and closing (gating) of phosphorylated channels is driven by ATP binding and hydrolysis at the NBDs. This review summarizes available information on structure and mechanism of the CFTR protein, with a particular focus on atomic-level insight gained from recent cryo-electron microscopic structures and on the molecular mechanisms of channel gating and its regulation. The pharmacological mechanisms of small molecules targeting CFTR's ion channel function, aimed at treating patients suffering from CF and other diseases, are briefly discussed.
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Affiliation(s)
- László Csanády
- Department of Medical Biochemistry, Semmelweis University , Budapest , Hungary ; MTA-SE Ion Channel Research Group, Budapest , Hungary ; Department of Neuroscience, Physiology and Pharmacology, University College London , London , United Kingdom ; and Laboratory of Cardiac/Membrane Physiology, The Rockefeller University , New York, New York
| | - Paola Vergani
- Department of Medical Biochemistry, Semmelweis University , Budapest , Hungary ; MTA-SE Ion Channel Research Group, Budapest , Hungary ; Department of Neuroscience, Physiology and Pharmacology, University College London , London , United Kingdom ; and Laboratory of Cardiac/Membrane Physiology, The Rockefeller University , New York, New York
| | - David C Gadsby
- Department of Medical Biochemistry, Semmelweis University , Budapest , Hungary ; MTA-SE Ion Channel Research Group, Budapest , Hungary ; Department of Neuroscience, Physiology and Pharmacology, University College London , London , United Kingdom ; and Laboratory of Cardiac/Membrane Physiology, The Rockefeller University , New York, New York
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15
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Functional characterization reveals that zebrafish CFTR prefers to occupy closed channel conformations. PLoS One 2018; 13:e0209862. [PMID: 30596737 PMCID: PMC6312236 DOI: 10.1371/journal.pone.0209862] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/12/2018] [Indexed: 12/19/2022] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR), the culprit behind the genetic disease cystic fibrosis (CF), is a phosphorylation-activated, but ATP-gated anion channel. Studies of human CFTR over the past two decades have provided an in-depth understanding of how CFTR works as an ion channel despite its structural resemblance to ABC transporters. Recently-solved cryo-EM structures of unphosphorylated human and zebrafish CFTR (hCFTR and zCFTR), as well as phosphorylated ATP-bound zebrafish and human CFTR offer an unprecedented opportunity to understand CFTR's function at a molecular level. Interestingly, despite millions of years of phylogenetic distance between human and zebrafish, the structures of zCFTR and hCFTR exhibit remarkable similarities. In the current study, we characterized biophysical and pharmacological properties of zCFTR with the patch-clamp technique, and showed surprisingly very different functional properties between these two orthologs. First, while hCFTR has a single-channel conductance of 8.4 pS with a linear I-V curve, zCFTR shows an inwardly-rectified I-V relationship with a single-channel conductance of ~3.5 pS. Second, single-channel gating behaviors of phosphorylated zCFTR are very different from those of hCFTR, featuring a very low open probability Po (0.03 ± 0.02, vs. ~0.50 for hCFTR) with exceedingly long closed events and brief openings. In addition, unlike hCFTR where each open burst is clearly defined with rare short-lived flickery closures, the open bursts of zCFTR are not easily resolved. Third, although abolishing ATP hydrolysis by replacing the catalytic glutamate with glutamine (i.e., E1372Q) drastically prolongs the open bursts defined by the macroscopic relaxation analysis in zCFTR, the Po within a "locked-open" burst of E1372Q-zCFTR is only ~ 0.35 (vs. Po > 0.94 in E1371Q-hCFTR). Collectively, our data not only provide a reasonable explanation for the unexpected closed-state structure of phosphorylated E1372Q-zCFTR with a canonical ATP-bound dimer of the nucleotide binding domains (NBDs), but also implicate significant structural and functional differences between these two evolutionarily distant orthologs.
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16
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Yeh JT, Yu YC, Hwang TC. Structural mechanisms for defective CFTR gating caused by the Q1412X mutation, a severe Class VI pathogenic mutation in cystic fibrosis. J Physiol 2018; 597:543-560. [PMID: 30408177 DOI: 10.1113/jp277042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/06/2018] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Electrophysiological characterization of Q1412X-CFTR, a C-terminal truncation mutation of cystic fibrosis transmembrane conductance regulator (CFTR) associated with the severe form of cystic fibrosis (CF), reveals a gating defect that has not been reported previously. Mechanistic investigations of the gating deficit in Q1412X-CFTR suggest that the reduced open probability in Q1412X-CFTR is the result of a disruption of the function of the second ATP binding site (or site 2) in the nucleotide binding domains (NBDs). Detailed comparisons of several mutations with different degrees of truncation in the C-terminal region of NBD2 reveal the importance of the last two beta-strands in NBD2 for maintaining proper gating functions. The results of the present study also show that the application of clinically-approved drugs (VX-770 and VX-809) can greatly enhance the function of Q1412X, providing in vitro evidence for a therapeutic strategy employing both reagents for patients bearing Q1412X or similar truncation mutations. ABSTRACT Cystic fibrosis (CF) is caused by loss-of-function mutations of cystic fibrosis transmembrane conductance regulator (CFTR), a phosphorylation-activated but ATP-gated chloride channel. Based on the molecular mechanism of CF pathogenesis, disease-associated mutations are categorized into six classes. Among them, Class VI, whose members include some of the C-terminal truncation mutations such as Q1412X, is defined as decreased membrane expression because of a faster turnover rate. In the present study, we characterized the functional properties of Q1412X-CFTR, a severe-form premature stop codon mutation. We confirmed previous findings of a ∼90% decrease in membrane expression but found a ∼95% reduction in the open probability (Po ). Detailed kinetic studies support the idea that the gating defect is the result of a dysfunctional ATP-binding site 2 in the nucleotide binding domains (NBDs). Because the Q1412X mutation results in a deletion of the last two beta-strands in NBD2 and the whole C-terminal region, we further characterized truncation mutations with different degrees of deletion in this segment. Mutations that completely or partially remove the C-terminus of CFTR at the same time as keeping an intact NBD2 (i.e. D1425X and S1455X) assume gating function almost identical to that of wild-type channels. However, the deletion of the last beta-strand in the NBD2 (i.e. N1419X) causes gating dysfunction that is milder than that of Q1412X. Thus, normal CFTR gating requires structural integrity of NBD2. Moreover, our observation that clinically-approved VX-809 (Lumacaftor, Vertex Pharmaceuticals, Boston, MA, USA) and VX-770 (Ivacaftor, Vertex Pharmaceuticals, Boston, MA, USA) significantly enhance the overall function of Q1412X-CFTR provides the conceptual basis for the treatment of patients carrying this mutation.
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Affiliation(s)
- Jiunn-Tyng Yeh
- Interdisciplinary Neuroscience Program.,Dalton Cardiovascular Research Center
| | - Ying-Chun Yu
- Dalton Cardiovascular Research Center.,Department of Pharmacology and Physiology, School of Medicine, University of Missouri-Columbia, MO, USA
| | - Tzyh-Chang Hwang
- Interdisciplinary Neuroscience Program.,Dalton Cardiovascular Research Center.,Department of Pharmacology and Physiology, School of Medicine, University of Missouri-Columbia, MO, USA
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17
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Wang Y, Cai Z, Gosling M, Sheppard DN. Potentiation of the cystic fibrosis transmembrane conductance regulator Cl− channel by ivacaftor is temperature independent. Am J Physiol Lung Cell Mol Physiol 2018; 315:L846-L857. [DOI: 10.1152/ajplung.00235.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ivacaftor is the first drug to target directly defects in the cystic fibrosis transmembrane conductance regulator (CFTR), which causes cystic fibrosis (CF). To understand better how ivacaftor potentiates CFTR channel gating, here we investigated the effects of temperature on its action. As a control, we studied the benzimidazolone UCCF-853, which potentiates CFTR by a different mechanism. Using the patch-clamp technique and cells expressing recombinant CFTR, we studied the single-channel behavior of wild-type and F508del-CFTR, the most common CF mutation. Raising the temperature of the intracellular solution from 23 to 37°C increased the frequency but reduced the duration of wild-type and F508del-CFTR channel openings. Although the open probability ( Po) of wild-type CFTR increased progressively as temperature was elevated, the relationship between Po and temperature for F508del-CFTR was bell-shaped with a maximum Po at ~30°C. For wild-type CFTR and to a greatly reduced extent F508del-CFTR, the temperature dependence of channel gating was asymmetric with the opening rate demonstrating greater temperature sensitivity than the closing rate. At all temperatures tested, ivacaftor and UCCF-853 potentiated wild-type and F508del-CFTR. Strikingly, ivacaftor but not UCCF-853 abolished the asymmetric temperature dependence of CFTR channel gating. At all temperatures tested, Po values of wild-type CFTR in the presence of ivacaftor were approximately double those of F508del-CFTR, which were equivalent to or greater than those of wild-type CFTR at 37°C in the absence of the drug. We conclude that the principal effect of ivacaftor is to promote channel opening to abolish the temperature dependence of CFTR channel gating.
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Affiliation(s)
- Yiting Wang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Zhiwei Cai
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Martin Gosling
- Enterprise Therapeutics, Sussex Innovation Centre, University of Sussex, Science Park Square, Brighton, United Kingdom
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - David N. Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
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18
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Langron E, Prins S, Vergani P. Potentiation of the cystic fibrosis transmembrane conductance regulator by VX-770 involves stabilization of the pre-hydrolytic, O 1 state. Br J Pharmacol 2018; 175:3990-4002. [PMID: 30107029 DOI: 10.1111/bph.14475] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/30/2018] [Accepted: 08/05/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Cystic fibrosis (CF) is a debilitating hereditary disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes an anion channel. Wild type-CFTR gating is a non-equilibrium process. After ATP binding, CFTR enters a stable open state (O1 ). ATP hydrolysis leads it to a short-lived post-hydrolytic open state (O2 ), from which channels close. Here, we use mutations to probe the mechanism of VX-770, the first compound directly targeting the CFTR protein approved for treatment of CF. D1370N and K1250R mutations reduce or abolish catalytic activity, simplifying the gating scheme to an equilibrium (C↔O1 ); K464A-CFTR has a destabilized O1 state and rarely closes via hydrolysis. EXPERIMENTAL APPROACH Potentiation by VX-770 was measured using microscopic imaging of HEK293 cells expressing an anion-sensitive YFP-CFTR. A simple mathematical model was used to predict fluorescence quenching following extracellular iodide addition and estimate CFTR conductance. Membrane density of CFTR channels was measured in a parallel assay, using CFTR-pHTomato. KEY RESULTS VX-770 strongly potentiated WT-CFTR, D1370N-CFTR and K1250R-CFTR. K464A-CFTR was also strongly potentiated, regardless of whether it retained catalytic activity or not. CONCLUSIONS AND IMPLICATIONS Similar potentiation of hydrolytic and non-hydrolytic mutants suggests that VX-770 increases CFTR open probability mainly by stabilizing pre-hydrolytic O1 states with respect to closed states. Potentiation of K464A-CFTR channels suggests action of VX-770 did not strongly alter conformational dynamics at site 1. Understanding potentiator mechanism could help develop improved treatment for CF patients. The fluorescence assay presented here is a robust tool for such investigations.
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Affiliation(s)
- Emily Langron
- Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Stella Prins
- Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Paola Vergani
- Neuroscience, Physiology and Pharmacology, University College London, London, UK
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19
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Molinski SV, Ahmadi S, Ip W, Ouyang H, Villella A, Miller JP, Lee PS, Kulleperuma K, Du K, Di Paola M, Eckford PD, Laselva O, Huan LJ, Wellhauser L, Li E, Ray PN, Pomès R, Moraes TJ, Gonska T, Ratjen F, Bear CE. Orkambi® and amplifier co-therapy improves function from a rare CFTR mutation in gene-edited cells and patient tissue. EMBO Mol Med 2018; 9:1224-1243. [PMID: 28667089 PMCID: PMC5582412 DOI: 10.15252/emmm.201607137] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The combination therapy of lumacaftor and ivacaftor (Orkambi®) is approved for patients bearing the major cystic fibrosis (CF) mutation: ΔF508. It has been predicted that Orkambi® could treat patients with rarer mutations of similar “theratype”; however, a standardized approach confirming efficacy in these cohorts has not been reported. Here, we demonstrate that patients bearing the rare mutation: c.3700 A>G, causing protein misprocessing and altered channel function—similar to ΔF508‐CFTR, are unlikely to yield a robust Orkambi® response. While in silico and biochemical studies confirmed that this mutation could be corrected and potentiated by lumacaftor and ivacaftor, respectively, this combination led to a minor in vitro response in patient‐derived tissue. A CRISPR/Cas9‐edited bronchial epithelial cell line bearing this mutation enabled studies showing that an “amplifier” compound, effective in increasing the levels of immature CFTR protein, augmented the Orkambi® response. Importantly, this “amplifier” effect was recapitulated in patient‐derived nasal cultures—providing the first evidence for its efficacy in augmenting Orkambi® in tissues harboring a rare CF‐causing mutation. We propose that this multi‐disciplinary approach, including creation of CRISPR/Cas9‐edited cells to profile modulators together with validation using primary tissue, will facilitate therapy development for patients with rare CF mutations.
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Affiliation(s)
- Steven V Molinski
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Saumel Ahmadi
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Wan Ip
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Hong Ouyang
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | | | | | - Po-Shun Lee
- Proteostasis Therapeutics, Cambridge, MA, USA
| | - Kethika Kulleperuma
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Kai Du
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Michelle Di Paola
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Paul Dw Eckford
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Onofrio Laselva
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Ling Jun Huan
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Leigh Wellhauser
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Ellen Li
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Peter N Ray
- Division of Molecular Genetics, Hospital for Sick Children, Toronto, ON, Canada
| | - Régis Pomès
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Theo J Moraes
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Tanja Gonska
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Felix Ratjen
- Division of Respiratory Medicine, Hospital for Sick Children, Toronto, ON, Canada
| | - Christine E Bear
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada .,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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20
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Hwang TC, Yeh JT, Zhang J, Yu YC, Yeh HI, Destefano S. Structural mechanisms of CFTR function and dysfunction. J Gen Physiol 2018; 150:539-570. [PMID: 29581173 PMCID: PMC5881446 DOI: 10.1085/jgp.201711946] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/05/2018] [Indexed: 12/18/2022] Open
Abstract
Hwang et al. integrate new structural insights with prior functional studies to reveal the functional anatomy of CFTR chloride channels. Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) chloride channel plays a critical role in regulating transepithelial movement of water and electrolyte in exocrine tissues. Malfunction of the channel because of mutations of the cftr gene results in CF, the most prevalent lethal genetic disease among Caucasians. Recently, the publication of atomic structures of CFTR in two distinct conformations provides, for the first time, a clear overview of the protein. However, given the highly dynamic nature of the interactions among CFTR’s various domains, better understanding of the functional significance of these structures requires an integration of these new structural insights with previously established biochemical/biophysical studies, which is the goal of this review.
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Affiliation(s)
- Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO .,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO.,Department of Biological Engineering, University of Missouri, Columbia, MO
| | - Jiunn-Tyng Yeh
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO
| | - Jingyao Zhang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO.,Department of Biological Engineering, University of Missouri, Columbia, MO
| | - Ying-Chun Yu
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Han-I Yeh
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Samantha Destefano
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
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21
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Yang Z, Hildebrandt E, Jiang F, Aleksandrov AA, Khazanov N, Zhou Q, An J, Mezzell AT, Xavier BM, Ding H, Riordan JR, Senderowitz H, Kappes JC, Brouillette CG, Urbatsch IL. Structural stability of purified human CFTR is systematically improved by mutations in nucleotide binding domain 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1193-1204. [PMID: 29425673 DOI: 10.1016/j.bbamem.2018.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/19/2018] [Accepted: 02/05/2018] [Indexed: 12/17/2022]
Abstract
The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is an ABC transporter containing two transmembrane domains forming a chloride ion channel, and two nucleotide binding domains (NBD1 and NBD2). CFTR has presented a formidable challenge to obtain monodisperse, biophysically stable protein. Here we report a comprehensive study comparing effects of single and multiple NBD1 mutations on stability of both the NBD1 domain alone and on purified full length human CFTR. Single mutations S492P, A534P, I539T acted additively, and when combined with M470V, S495P, and R555K cumulatively yielded an NBD1 with highly improved structural stability. Strategic combinations of these mutations strongly stabilized the domain to attain a calorimetric Tm > 70 °C. Replica exchange molecular dynamics simulations on the most stable 6SS-NBD1 variant implicated fluctuations, electrostatic interactions and side chain packing as potential contributors to improved stability. Progressive stabilization of NBD1 directly correlated with enhanced structural stability of full-length CFTR protein. Thermal unfolding of the stabilized CFTR mutants, monitored by changes in intrinsic fluorescence, demonstrated that Tm could be shifted as high as 67.4 °C in 6SS-CFTR, more than 20 °C higher than wild-type. H1402S, an NBD2 mutation, conferred CFTR with additional thermal stability, possibly by stabilizing an NBD-dimerized conformation. CFTR variants with NBD1-stabilizing mutations were expressed at the cell surface in mammalian cells, exhibited ATPase and channel activity, and retained these functions to higher temperatures. The capability to produce enzymatically active CFTR with improved structural stability amenable to biophysical and structural studies will advance mechanistic investigations and future cystic fibrosis drug development.
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Affiliation(s)
- Zhengrong Yang
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Ellen Hildebrandt
- Department of Cell Biology and Biochemistry, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA
| | - Fan Jiang
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA
| | - Andrei A Aleksandrov
- Department of Biochemistry and Biophysics and Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Netaly Khazanov
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Qingxian Zhou
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jianli An
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Andrew T Mezzell
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA
| | - Bala M Xavier
- Department of Cell Biology and Biochemistry, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA
| | - Haitao Ding
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA
| | - John R Riordan
- Department of Biochemistry and Biophysics and Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Hanoch Senderowitz
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - John C Kappes
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA; Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL 35233, USA
| | | | - Ina L Urbatsch
- Department of Cell Biology and Biochemistry, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA.
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22
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Jih KY, Lin WY, Sohma Y, Hwang TC. CFTR potentiators: from bench to bedside. Curr Opin Pharmacol 2017; 34:98-104. [PMID: 29073476 DOI: 10.1016/j.coph.2017.09.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 09/15/2017] [Accepted: 09/26/2017] [Indexed: 01/14/2023]
Abstract
One major breakthrough in cystic fibrosis research in the past decade is the development of drugs that target the root cause of the disease-dysfunctional CFTR protein. One of the compounds, Ivacaftor or Kalydeco, which has been approved for clinical use since 2012, acts by promoting the gating function of CFTR. Our recent studies have led to a gating model that features energetic coupling between nucleotide-binding domain (NBD) dimerization and gate opening/closing in CFTR's transmembrane domains (TMDs). Based on this model, we showed that ATP analogs can enhance CFTR gating by facilitating NBD dimerization, whereas Ivacaftor works by stabilizing the open channel conformation of the TMDs. This latter idea also explains the near omnipotence of Ivacaftor. Furthermore, this model identifies multiple approaches to synergistically boost the open probability of CFTR by influencing distinct molecular events that control gating conformational changes.
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Affiliation(s)
- Kang-Yang Jih
- Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Wen-Ying Lin
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yoshiro Sohma
- Department of Pharmacology, Keio University, Tokyo, Japan; Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Tzyh-Chang Hwang
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA.
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Yeh HI, Sohma Y, Conrath K, Hwang TC. A common mechanism for CFTR potentiators. J Gen Physiol 2017; 149:1105-1118. [PMID: 29079713 PMCID: PMC5715911 DOI: 10.1085/jgp.201711886] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/10/2017] [Indexed: 01/29/2023] Open
Abstract
VX-770 is a potentiator of the CFTR channel and an approved therapy for cystic fibrosis. Yeh et al. find that the apparent affinity of a new potentiator, GLPG1837, is state dependent and propose an allosteric modulation model to explain the potency and efficacy of CFTR potentiators. Cystic fibrosis (CF) is a channelopathy caused by loss-of-function mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a phosphorylation-activated and adenosine triphosphate (ATP)–gated chloride channel. In the past few years, high-throughput drug screening has successfully realized the first US Food and Drug Administration–approved therapy for CF, called ivacaftor (or VX-770). A more recent CFTR potentiator, GLPG1837 (N-(3-carbamoyl-5,5,7,7-tetramethyl-4,7-dihydro-5H-thieno[2,3-c]pyran-2-yl)-1H-pyrazole-3-carboxamide), has been shown to exhibit a higher efficacy than ivacaftor for the G551D mutation, yet the underlying mechanism of GLPG1837 remains unclear. Here we find that despite their differences in potency and efficacy, GLPG1837 and VX-770 potentiate CFTR gating in a remarkably similar manner. Specifically, they share similar effects on single-channel kinetics of wild-type CFTR. Their actions are independent of nucleotide-binding domain (NBD) dimerization and ATP hydrolysis, critical steps controlling CFTR’s gate opening and closing, respectively. By applying the two reagents together, we provide evidence that GLPG1837 and VX-770 likely compete for the same site, whereas GLPG1837 and the high-affinity ATP analogue 2′-deoxy-N6-(2-phenylethyl)-adenosine-5′-O-triphosphate (dPATP) work synergistically through two different sites. We also find that the apparent affinity for GLPG1837 is dependent on the open probability of the channel, suggesting a state-dependent binding of the drug to CFTR (higher binding affinity for the open state than the closed state), which is consistent with the classic mechanism for allosteric modulation. We propose a simple four-state kinetic model featuring an energetic coupling between CFTR gating and potentiator binding to explain our experimental results.
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Affiliation(s)
- Han-I Yeh
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Yoshiro Sohma
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO.,Department of Pharmaceutical Sciences, School of Pharmacy and Center for Medical Science, International University of Health and Welfare, Tochigi, Japan
| | | | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
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24
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Callebaut I, Hoffmann B, Lehn P, Mornon JP. Molecular modelling and molecular dynamics of CFTR. Cell Mol Life Sci 2017; 74:3-22. [PMID: 27717958 PMCID: PMC11107702 DOI: 10.1007/s00018-016-2385-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/11/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) protein is a member of the ATP-binding cassette (ABC) transporter superfamily that functions as an ATP-gated channel. Considerable progress has been made over the last years in the understanding of the molecular basis of the CFTR functions, as well as dysfunctions causing the common genetic disease cystic fibrosis (CF). This review provides a global overview of the theoretical studies that have been performed so far, especially molecular modelling and molecular dynamics (MD) simulations. A special emphasis is placed on the CFTR-specific evolution of an ABC transporter framework towards a channel function, as well as on the understanding of the effects of disease-causing mutations and their specific modulation. This in silico work should help structure-based drug discovery and design, with a view to develop CFTR-specific pharmacotherapeutic approaches for the treatment of CF in the context of precision medicine.
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Affiliation(s)
- Isabelle Callebaut
- UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, IUC, Case 115, IMPMC, Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005, Paris Cedex 05, France.
| | - Brice Hoffmann
- UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, IUC, Case 115, IMPMC, Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005, Paris Cedex 05, France
| | - Pierre Lehn
- INSERM U1078, SFR ScInBioS, Université de Bretagne Occidentale, Brest, France
| | - Jean-Paul Mornon
- UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, IUC, Case 115, IMPMC, Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005, Paris Cedex 05, France
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25
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Laselva O, Molinski S, Casavola V, Bear CE. The investigational Cystic Fibrosis drug Trimethylangelicin directly modulates CFTR by stabilizing the first membrane-spanning domain. Biochem Pharmacol 2016; 119:85-92. [PMID: 27614011 DOI: 10.1016/j.bcp.2016.09.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 09/06/2016] [Indexed: 12/24/2022]
Abstract
Cystic Fibrosis (CF) is caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. The most common mutation, deletion of phenylalanine 508 (F508del), disrupts tertiary assembly, causing protein misprocessing and loss of CFTR function in epithelial tissues. Lumacaftor (VX-809) is a Class 1 corrector molecule shown to partially rescue misprocessing of F508del and together with the potentiator of channel activity: ivacaftor (VX-770) has been approved for treatment of CF patients homozygous for the F508del mutation. The specificity of these modulators for CFTR is thought to be conferred through direct binding. Trimethylangelicin (TMA) is a distinct small molecule modulator, previously shown to exhibit both corrector and potentiator activities. We were prompted to determine if TMA also mediates these activities by direct binding. Interestingly, we found that like VX-770, TMA was effective in enhancing anion efflux mediated by purified WT-CFTR reconstituted in phospholipid liposomes. Furthermore, like VX-809, TMA was effective in stabilizing the functional expression of CFTR lacking the regulatory "R" domain or second nucleotide-binding domain (NBD2). The smallest domain that was stabilized by TMA binding was the first membrane-spanning domain (MSD1) as previously observed for VX-809. Together, our findings support the claim that TMA binds directly to CFTR, and despite its distinct chemical structure, shares similar mechanisms as VX-770 and VX-809 to potentiate and stabilize CFTR, respectively.
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Affiliation(s)
- Onofrio Laselva
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Italy; Programme in Molecular Structure and Function, Hospital for Sick Children, Toronto, Canada
| | - Steven Molinski
- Programme in Molecular Structure and Function, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Canada
| | - Valeria Casavola
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Italy
| | - Christine E Bear
- Programme in Molecular Structure and Function, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Canada; Department of Physiology, University of Toronto, Canada.
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26
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Lin WY, Sohma Y, Hwang TC. Synergistic Potentiation of Cystic Fibrosis Transmembrane Conductance Regulator Gating by Two Chemically Distinct Potentiators, Ivacaftor (VX-770) and 5-Nitro-2-(3-Phenylpropylamino) Benzoate. Mol Pharmacol 2016; 90:275-85. [PMID: 27413118 PMCID: PMC4998663 DOI: 10.1124/mol.116.104570] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/12/2016] [Indexed: 01/12/2023] Open
Abstract
Cystic fibrosis (CF) is caused by loss-of-function mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene encoding a phosphorylation-activated but ATP-gated chloride channel. Previous studies suggested that VX-770 [ivacaftor, N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide], a CFTR potentiator now used in clinics, increases the open probability of CFTR by shifting the gating conformational changes to favor the open channel configuration. Recently the chloride channel blocker and CFTR potentiator 5-nitro-2-(3-phenylpropylamino) benzoate (NPPB) has been reported to enhance CFTR activity by a mechanism that exploits the ATP hydrolysis-driven, nonequilibrium gating mechanism unique to CFTR. Surprisingly however, NPPB increased the activity of nonhydrolytic G551D-CFTR, the third most common disease-associated mutation. Here, we further investigated the mechanism of NPPB's effects on CFTR gating by assessing its interaction with well-studied VX-770. Interestingly, once G551D-CFTR was maximally potentiated by VX-770, NPPB further increased its activity. However, quantitative analysis of this drug-drug interaction suggests that this pharmacologic synergism is not due to independent actions of NPPB and VX-770 on CFTR gating; instead, our data support a dependent mechanism involving two distinct binding sites. This latter idea is further supported by the observation that the locked-open time of a hydrolysis-deficient mutant K1250A was shortened by NPPB but prolonged by VX-770. In addition, the effectiveness of NPPB, but not of VX-770, was greatly diminished in a mutant whose second nucleotide-binding domain was completely removed. Interpreting these results under the framework of current understanding of CFTR gating not only reveals insights into the mechanism of action for different CFTR potentiators but also brings us one step forward to a more complete schematic for CFTR gating.
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Affiliation(s)
- Wen-Ying Lin
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (W.-Y.L., T.-C.H.); Department of Pharmacology, School of Medicine, Keio University, Tokyo Japan (Y.S.)
| | - Yoshiro Sohma
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (W.-Y.L., T.-C.H.); Department of Pharmacology, School of Medicine, Keio University, Tokyo Japan (Y.S.)
| | - Tzyh-Chang Hwang
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (W.-Y.L., T.-C.H.); Department of Pharmacology, School of Medicine, Keio University, Tokyo Japan (Y.S.)
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27
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Wang G, Linsley R, Norimatsu Y. External Zn2+binding to cysteine-substituted cystic fibrosis transmembrane conductance regulator constructs regulates channel gating and curcumin potentiation. FEBS J 2016; 283:2458-75. [DOI: 10.1111/febs.13752] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 05/02/2016] [Accepted: 05/11/2016] [Indexed: 01/22/2023]
Affiliation(s)
- Guangyu Wang
- Department of Physiology and Pharmacology; Oregon Health & Sciences University; Portland OR USA
- Department of Drug Research and Development; Institute of Biophysical Medico-chemistry; Reno NV USA
- Department of Physiology and Membrane Biology; University of California School of Medicine; Davis CA USA
| | | | - Yohei Norimatsu
- Department of Physiology; Kirksville College of Osteopathic Medicine; A.T. Still University; Kirksville MO USA
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28
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Contreras-Vite JA, Cruz-Rangel S, De Jesús-Pérez JJ, Figueroa IAA, Rodríguez-Menchaca AA, Pérez-Cornejo P, Hartzell HC, Arreola J. Revealing the activation pathway for TMEM16A chloride channels from macroscopic currents and kinetic models. Pflugers Arch 2016; 468:1241-1257. [PMID: 27138167 DOI: 10.1007/s00424-016-1830-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/19/2016] [Accepted: 04/21/2016] [Indexed: 01/11/2023]
Abstract
TMEM16A (ANO1), the pore-forming subunit of calcium-activated chloride channels, regulates several physiological and pathophysiological processes such as smooth muscle contraction, cardiac and neuronal excitability, salivary secretion, tumour growth and cancer progression. Gating of TMEM16A is complex because it involves the interplay between increases in intracellular calcium concentration ([Ca(2+)]i), membrane depolarization, extracellular Cl(-) or permeant anions and intracellular protons. Our goal here was to understand how these variables regulate TMEM16A gating and to explain four observations. (a) TMEM16A is activated by voltage in the absence of intracellular Ca(2+). (b) The Cl(-) conductance is decreased after reducing extracellular Cl(-) concentration ([Cl(-)]o). (c) ICl is regulated by physiological concentrations of [Cl(-)]o. (d) In cells dialyzed with 0.2 μM [Ca(2+)]i, Cl(-) has a bimodal effect: at [Cl(-)]o <30 mM TMEM16A current activates with a monoexponential time course, but above 30 mM, [Cl(-)]o ICl activation displays fast and slow kinetics. To explain the contribution of Vm, Ca(2+) and Cl(-) to gating, we developed a 12-state Markov chain model. This model explains TMEM16A activation as a sequential, direct, and Vm-dependent binding of two Ca(2+) ions coupled to a Vm-dependent binding of an external Cl(-) ion, with Vm-dependent transitions between states. Our model predicts that extracellular Cl(-) does not alter the apparent Ca(2+) affinity of TMEM16A, which we corroborated experimentally. Rather, extracellular Cl(-) acts by stabilizing the open configuration induced by Ca(2+) and by contributing to the Vm dependence of activation.
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Affiliation(s)
- Juan A Contreras-Vite
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, Zona Universitaria, San Luis Potosí, SLP 78290, México
| | - Silvia Cruz-Rangel
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, Zona Universitaria, San Luis Potosí, SLP 78290, México
| | - José J De Jesús-Pérez
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, Zona Universitaria, San Luis Potosí, SLP 78290, México
| | - Iván A Aréchiga Figueroa
- CONACYT - Universidad Autónoma de San Luis Potosí School of Medicine, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, México
| | - Aldo A Rodríguez-Menchaca
- Department of Physiology, Universidad Autónoma de San Luis Potosí School of Medicine, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, México
| | - Patricia Pérez-Cornejo
- Department of Physiology, Universidad Autónoma de San Luis Potosí School of Medicine, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, México
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, Zona Universitaria, San Luis Potosí, SLP 78290, México.
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Cholon DM, Esther CR, Gentzsch M. Efficacy of lumacaftor-ivacaftor for the treatment of cystic fibrosis patients homozygous for the F508del-CFTR mutation. EXPERT REVIEW OF PRECISION MEDICINE AND DRUG DEVELOPMENT 2016; 1:235-243. [PMID: 27482545 DOI: 10.1080/23808993.2016.1175299] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cystic fibrosis (CF) results from mutations in the CF transmembrane conductance regulator (CFTR) gene, which codes for the CFTR channel protein. The most common mutation in CF is F508del, which produces a misfolded protein with diminished channel activity. The development of small-molecule CFTR-modulator compounds offers an exciting and novel approach for pharmacological treatment of CF. The corrector lumacaftor helps rescue F508del-CFTR to the cell surface, and potentiator ivacaftor increases F508del-CFTR channel activity. The combination of lumacaftor-ivacaftor (Vertex Pharmaceuticals Incorporated) represents the first FDA-approved therapy for CF patients with two copies of the F508del mutation. Although this combination therapy is the first treatment to directly target the F508del-CFTR mutation, patients taking this drug displayed only modest improvements in lung function. This article summarizes recent data from clinical trials and research discoveries relating to the lumacaftor-ivacaftor treatment, and considers options for identifying future therapies that will be most efficacious for all CF patients.
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Affiliation(s)
- Deborah M Cholon
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Charles R Esther
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Division of Pediatric Pulmonology, Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Martina Gentzsch
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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30
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Linsdell P. Anion conductance selectivity mechanism of the CFTR chloride channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:740-7. [DOI: 10.1016/j.bbamem.2016.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/11/2016] [Accepted: 01/13/2016] [Indexed: 02/08/2023]
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Wang W, Hong JS, Rab A, Sorscher EJ, Kirk KL. Robust Stimulation of W1282X-CFTR Channel Activity by a Combination of Allosteric Modulators. PLoS One 2016; 11:e0152232. [PMID: 27007499 PMCID: PMC4805204 DOI: 10.1371/journal.pone.0152232] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/10/2016] [Indexed: 11/18/2022] Open
Abstract
W1282X is a common nonsense mutation among cystic fibrosis patients that results in the production of a truncated Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Here we show that the channel activity of the W1282X-CFTR polypeptide is exceptionally low in excised membrane patches at normally saturating doses of ATP and PKA (single channel open probability (PO) < 0.01). However, W1282X-CFTR channels were stimulated by two CFTR modulators, the FDA-approved VX-770 and the dietary compound curcumin. Each of these compounds is an allosteric modulator of CFTR gating that promotes channel activity in the absence of the native ligand, ATP. Although W1282X-CFTR channels were stimulated by VX-770 in the absence of ATP their activities remained dependent on PKA phosphorylation. Thus, activated W1282X-CFTR channels should remain under physiologic control by cyclic nucleotide signaling pathways in vivo. VX-770 and curcumin exerted additive effects on W1282X-CFTR channel gating (opening/closing) in excised patches such that the Po of the truncated channel approached unity (> 0.9) when treated with both modulators. VX-770 and curcumin also additively stimulated W1282X-CFTR mediated currents in polarized FRT epithelial monolayers. In this setting, however, the stimulated W1282X-CFTR currents were smaller than those mediated by wild type CFTR (3-5%) due presumably to lower expression levels or cell surface targeting of the truncated protein. Combining allosteric modulators of different mechanistic classes is worth considering as a treatment option for W1282X CF patients perhaps when coupled with maneuvers to increase expression of the truncated protein.
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Affiliation(s)
- Wei Wang
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
- * E-mail: (WW); (KLK)
| | - Jeong S. Hong
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
| | - Andras Rab
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
| | - Eric J. Sorscher
- Department of Pediatrics, Emory University, Atlanta, GA, 30322, United States of America
| | - Kevin L. Kirk
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America
- * E-mail: (WW); (KLK)
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Yu YC, Sohma Y, Hwang TC. On the mechanism of gating defects caused by the R117H mutation in cystic fibrosis transmembrane conductance regulator. J Physiol 2016; 594:3227-44. [PMID: 26846474 DOI: 10.1113/jp271723] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 01/29/2016] [Indexed: 01/05/2023] Open
Abstract
KEY POINTS Two functional abnormalities of cystic fibrosis transmembrane conductance regulator (CFTR), a 25% reduction of the single-channel conductance (g) and a ∼13-fold lower open probability (Po ), were found with the R117H mutation that is associated with mild forms of cystic fibrosis. Characterizations of the gating defects of R117H-CFTR led to the conclusion that the mutation decreases Po by perturbing the gating conformational changes in CFTR's transmembrane domains (TMDs) without altering the function of the nucleotide binding domains (NBDs). Nonetheless, gating of the R117H-CFTR can be improved by a variety of pharmacological reagents supposedly acting on NBDs such as ATP analogues, or TMDs (e.g. VX-770 or nitrate). These reagents potentiate synergistically R117H-CFTR gating to a level that allows accurate assessments of its gating deficits. Our studies not only elucidate the mechanism underpinning gating dysfunction of R117H-CFTR, but also provide a mechanistic understanding of how VX-770 ameliorates the gating defects in the R117H mutant. ABSTRACT Cystic fibrosis (CF) is caused by loss-of-function mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene encoding a phosphorylation-activated, but ATP-gated chloride channel. In the current study, we investigated the mechanism responsible for the gating defects manifested in R117H-CFTR, an arginine-to-histidine substitution at position 117 of CFTR that is associated with mild forms of CF. We confirmed previous findings of a 25% decrease of the single-channel conductance (g) in R117H-CFTR, but found a ∼13-fold lower open probability (Po ). This dramatic gating deficit is not due to dysfunctional nucleotide binding domains (NBDs) as the mutation does not alter the apparent affinity for ATP, and the mutant channels respond to ATP analogues in a similar manner as wild-type CFTR. Furthermore, once ATP hydrolysis is abolished, the R117H mutant can be trapped in a prolonged 'burst opening' conformation that is proposed to be equipped with a stable NBD dimer. On the other hand, our results support the conclusion that the R117H mutation decreases Po by perturbing the gating conformational changes in CFTR's transmembrane domains as even when NBDs are kept at a dimerized configuration, Po is reduced by ∼10-fold. Moreover, our data demonstrate that a synergistic improvement of R117H-CFTR function can be accomplished with a combined regiment of VX-770 (Ivacaftor), nitrate ion (NO3 (-) ) and N(6) -(2-phenylethyl)-2'-deoxy-ATP (d-PATP), which almost completely rectifies the gating defect of R117H-CFTR. Clinical implications of our results are discussed.
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Affiliation(s)
- Ying-Chun Yu
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO, 65211, USA.,Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, MO, 65211, USA
| | - Yoshiro Sohma
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO, 65211, USA.,Department of Pharmacology, Keio University School of Medicine, Shinjuku, Tokyo, 160-8582, Japan
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO, 65211, USA.,Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, MO, 65211, USA
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Colemeadow J, Joyce H, Turcanu V. Precise treatment of cystic fibrosis – current treatments and perspectives for using CRISPR. EXPERT REVIEW OF PRECISION MEDICINE AND DRUG DEVELOPMENT 2016. [DOI: 10.1080/23808993.2016.1146077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Structural Changes Fundamental to Gating of the Cystic Fibrosis Transmembrane Conductance Regulator Anion Channel Pore. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 925:13-32. [PMID: 27311317 DOI: 10.1007/5584_2016_33] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial cell anion channel. Potentiator drugs used in the treatment of cystic fibrosis act on the channel to increase overall channel function, by increasing the stability of its open state and/or decreasing the stability of its closed state. The structure of the channel in either the open state or the closed state is not currently known. However, changes in the conformation of the protein as it transitions between these two states have been studied using functional investigation and molecular modeling techniques. This review summarizes our current understanding of the architecture of the transmembrane channel pore that controls the movement of chloride and other small anions, both in the open state and in the closed state. Evidence for different kinds of changes in the conformation of the pore as it transitions between open and closed states is described, as well as the mechanisms by which these conformational changes might be controlled to regulate normal channel gating. The ways that key conformational changes might be targeted by small compounds to influence overall CFTR activity are also discussed. Understanding the changes in pore structure that might be manipulated by such small compounds is key to the development of novel therapeutic strategies for the treatment of cystic fibrosis.
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Trimble AT, Donaldson SH. CFTR Modulator Therapies for Cystic Fibrosis. PEDIATRIC ALLERGY, IMMUNOLOGY, AND PULMONOLOGY 2015; 28:230-236. [PMID: 35923001 DOI: 10.1089/ped.2015.0583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The cloning of cystic fibrosis transmembrane conductance regulator (CFTR) set into motion a cascade of discoveries that have helped to reveal the underlying pathophysiologic basis of cystic fibrosis (CF). This discovery and the knowledge that followed have also provided the opportunity to target this basic defect, with the hope of reversing or preventing the serious clinical consequences that result from absent CFTR function. With the recent approval of 2 therapies that directly modulate CFTR function in more than half of the CF population, we are now at the beginning of a pathway to providing increasingly effective therapies that have the potential to provide a fundamental change in the outcome of most patients with CF.
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Affiliation(s)
- Aaron T Trimble
- Division of Pulmonary and Critical Care Medicine, Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Scott H Donaldson
- Division of Pulmonary and Critical Care Medicine, Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Wei S, Roessler BC, Icyuz M, Chauvet S, Tao B, Hartman JL, Kirk KL. Long-range coupling between the extracellular gates and the intracellular ATP binding domains of multidrug resistance protein pumps and cystic fibrosis transmembrane conductance regulator channels. FASEB J 2015; 30:1247-62. [PMID: 26606940 DOI: 10.1096/fj.15-278382] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/16/2015] [Indexed: 12/22/2022]
Abstract
The ABCC transporter subfamily includes pumps, the long and short multidrug resistance proteins (MRPs), and an ATP-gated anion channel, the cystic fibrosis transmembrane conductance regulator (CFTR). We show that despite their thermodynamic differences, these ABCC transporter subtypes use broadly similar mechanisms to couple their extracellular gates to the ATP occupancies of their cytosolic nucleotide binding domains. A conserved extracellular phenylalanine at this gate was a prime location for producing gain of function (GOF) mutants of a long MRP in yeast (Ycf1p cadmium transporter), a short yeast MRP (Yor1p oligomycin exporter), and human CFTR channels. Extracellular gate mutations rescued ATP binding mutants of the yeast MRPs and CFTR by increasing ATP sensitivity. Control ATPase-defective MRP mutants could not be rescued by this mechanism. A CFTR double mutant with an extracellular gate mutation plus a cytosolic GOF mutation was highly active (single-channel open probability >0.3) in the absence of ATP and protein kinase A, each normally required for CFTR activity. We conclude that all 3 ABCC transporter subtypes use similar mechanisms to couple their extracellular gates to ATP occupancy, and highly active CFTR channels that bypass defects in ATP binding or phosphorylation can be produced.
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Affiliation(s)
- Shipeng Wei
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Bryan C Roessler
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mert Icyuz
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sylvain Chauvet
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Binli Tao
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - John L Hartman
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kevin L Kirk
- *Department of Cell, Developmental, and Integrative Biology, Department of Genetics, and Department of Neurobiology, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Sorum B, Czégé D, Csanády L. Timing of CFTR pore opening and structure of its transition state. Cell 2015; 163:724-33. [PMID: 26496611 DOI: 10.1016/j.cell.2015.09.052] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/25/2015] [Accepted: 09/18/2015] [Indexed: 12/12/2022]
Abstract
In CFTR, the chloride ion channel mutated in cystic fibrosis (CF) patients, pore opening is coupled to ATP-binding-induced dimerization of two cytosolic nucleotide binding domains (NBDs) and closure to dimer disruption following ATP hydrolysis. CFTR opening rate, unusually slow because of its high-energy transition state, is further slowed by CF mutation ΔF508. Here, we exploit equilibrium gating of hydrolysis-deficient CFTR mutant D1370N and apply rate-equilibrium free-energy relationship analysis to estimate relative timing of opening movements in distinct protein regions. We find clear directionality of motion along the longitudinal protein axis and identify an opening transition-state structure with the NBD dimer formed but the pore still closed. Thus, strain at the NBD/pore-domain interface, the ΔF508 mutation locus, underlies the energetic barrier for opening. Our findings suggest a therapeutic opportunity to stabilize this transition-state structure pharmacologically in ΔF508-CFTR to correct its opening defect, an essential step toward restoring CFTR function.
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Affiliation(s)
- Ben Sorum
- Department of Medical Biochemistry, Semmelweis University, Tűzoltó u. 37-47, Budapest 1094, Hungary; MTA-SE Ion Channel Research Group, Semmelweis University, Tűzoltó u. 37-47, Budapest 1094, Hungary
| | - Dávid Czégé
- MTA-SE Ion Channel Research Group, Semmelweis University, Tűzoltó u. 37-47, Budapest 1094, Hungary
| | - László Csanády
- Department of Medical Biochemistry, Semmelweis University, Tűzoltó u. 37-47, Budapest 1094, Hungary; MTA-SE Ion Channel Research Group, Semmelweis University, Tűzoltó u. 37-47, Budapest 1094, Hungary.
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Molinski SV, Ahmadi S, Hung M, Bear CE. Facilitating Structure-Function Studies of CFTR Modulator Sites with Efficiencies in Mutagenesis and Functional Screening. ACTA ACUST UNITED AC 2015; 20:1204-17. [PMID: 26385858 DOI: 10.1177/1087057115605834] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/23/2015] [Indexed: 12/20/2022]
Abstract
There are nearly 2000 mutations in the CFTR gene associated with cystic fibrosis disease, and to date, the only approved drug, Kalydeco, has been effective in rescuing the functional expression of a small subset of these mutant proteins with defects in channel activation. However, there is currently an urgent need to assess other mutations for possible rescue by Kalydeco, and further, definition of the binding site of such modulators on CFTR would enhance our understanding of the mechanism of action of such therapeutics. Here, we describe a simple and rapid one-step PCR-based site-directed mutagenesis method to generate mutations in the CFTR gene. This method was used to generate CFTR mutants bearing deletions (p.Gln2_Trp846del, p.Ser700_Asp835del, p.Ile1234_Arg1239del) and truncation with polyhistidine tag insertion (p.Glu1172-3Gly-6-His*), which either recapitulate a disease phenotype or render tools for modulator binding site identification, with subsequent evaluation of drug responses using a high-throughput (384-well) membrane potential-sensitive fluorescence assay of CFTR channel activity within a 1 wk time frame. This proof-of-concept study shows that these methods enable rapid and quantitative comparison of multiple CFTR mutants to emerging drugs, facilitating future large-scale efforts to stratify mutants according to their "theratype" or most promising targeted therapy.
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Affiliation(s)
- Steven V Molinski
- Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Saumel Ahmadi
- Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Maurita Hung
- Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Christine E Bear
- Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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Lin WY, Yu YC. Interaction non grata between CFTR's correctors and potentiators. ANNALS OF TRANSLATIONAL MEDICINE 2015; 3:75. [PMID: 25992374 DOI: 10.3978/j.issn.2305-5839.2015.01.27] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 01/12/2015] [Indexed: 01/01/2023]
Affiliation(s)
- Wen-Ying Lin
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Ying-Chun Yu
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO 65211, USA
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