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Gao X, Yeh HI, Yang Z, Fan C, Jiang F, Howard RJ, Lindahl E, Kappes JC, Hwang TC. Allosteric inhibition of CFTR gating by CFTRinh-172 binding in the pore. Nat Commun 2024; 15:6668. [PMID: 39107303 PMCID: PMC11303713 DOI: 10.1038/s41467-024-50641-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 07/09/2024] [Indexed: 08/10/2024] Open
Abstract
Loss-of-function mutations of the CFTR gene cause the life-shortening genetic disease cystic fibrosis (CF), whereas overactivity of CFTR may lead to secretory diarrhea and polycystic kidney disease. While effective drugs targeting the CFTR protein have been developed for the treatment of CF, little progress has been made for diseases caused by hyper-activated CFTR. Here, we solve the cryo-EM structure of CFTR in complex with CFTRinh-172 (Inh-172), a CFTR gating inhibitor with promising potency and efficacy. We find that Inh-172 binds inside the pore of CFTR, interacting with amino acid residues from transmembrane segments (TMs) 1, 6, 8, 9, and 12 through mostly hydrophobic interactions and a salt bridge. Substitution of these residues lowers the apparent affinity of Inh-172. The inhibitor-bound structure reveals re-orientations of the extracellular segment of TMs 1, 8, and 12, supporting an allosteric modulation mechanism involving post-binding conformational changes. This allosteric inhibitory mechanism readily explains our observations that pig CFTR, which preserves all the amino acid residues involved in Inh-172 binding, exhibits a much-reduced sensitivity to Inh-172 and that the apparent affinity of Inh-172 is altered by the CF drug ivacaftor (i.e., VX-770) which enhances CFTR's activity through binding to a site also comprising TM8.
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Affiliation(s)
- Xiaolong Gao
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, 65211, USA.
| | - Han-I Yeh
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, 65211, USA
- Institute of Pharmacology, National Yang Ming Chiao Tung University, College of Medicine, Taipei, Taiwan
- Membrane Protein Structural Biology Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Zhengrong Yang
- Heersink School of Medicine, University of Alabama School of Medicine, Birmingham, AL, 35233, USA
| | - Chen Fan
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Fan Jiang
- Heersink School of Medicine, University of Alabama School of Medicine, Birmingham, AL, 35233, USA
| | - Rebecca J Howard
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Erik Lindahl
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - John C Kappes
- Heersink School of Medicine, University of Alabama School of Medicine, Birmingham, AL, 35233, USA
- Research Service, Birmingham Veterans Affairs Medical Center, Veterans Health Administration, Birmingham, AL, 35233, USA
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, 65211, USA.
- Institute of Pharmacology, National Yang Ming Chiao Tung University, College of Medicine, Taipei, Taiwan.
- Membrane Protein Structural Biology Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan.
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2
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Terlizzi V, Farrell PM. Update on advances in cystic fibrosis towards a cure and implications for primary care clinicians. Curr Probl Pediatr Adolesc Health Care 2024; 54:101637. [PMID: 38811287 DOI: 10.1016/j.cppeds.2024.101637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
During the past quarter century, the diagnosis and treatment of cystic fibrosis (CF) have been transformed by molecular sciences that initiated a new era with discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The knowledge gained from that breakthrough has had dramatic clinical impact. Although once a diagnostic dilemma with long delays, preventable deaths, and irreversible pathology, CF can now be routinely diagnosed shortly after birth through newborn screening programs. This strategy of pre-symptomatic identification has eliminated the common diagnostic "odyssey" that was a failure of the healthcare delivery system causing psychologically traumatic experiences for parents. Therapeutic advances of many kinds have culminated in CFTR modulator treatment that can reduce the effects of or even correct the molecular defect in the chloride channel -the basic cause of CF. This astonishing advance has transformed CF care as described fully herein. Despite this impressive progress, there are challenges and controversies in the delivery of care. Issues include how best to achieve high sensitivity newborn screening with acceptable specificity; what course of action is appropriate for children who are identified through the unavoidable incidental findings of screening tests (CFSPID/CRMS cases and heterozygote carriers); how best to ensure genetic counseling; when to initiate the very expensive but life-saving CFTR modulator drugs; how to identify new CFTR modulator drugs for patients with non-responsive CFTR variants; how to adjust other therapeutic modalities; and how to best partner with primary care clinicians. Progress always brings new challenges, and this has been evident worldwide for CF. Consequently, this article summarizes the major advances of recent years along with controversies and describes their implications with an international perspective.
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Affiliation(s)
- Vito Terlizzi
- Department of Pediatric Medicine, Meyer Children's Hospital IRCCS, Cystic Fibrosis Regional Reference Center, Viale Gaetano Pieraccini 24, Florence, Italy
| | - Philip M Farrell
- Departments of Pediatrics and Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Clinical Sciences Center (K4/948), 600 Highland Avenue, Madison, WI 53792, USA.
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3
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Taylor-Cousar JL, Robinson PD, Shteinberg M, Downey DG. CFTR modulator therapy: transforming the landscape of clinical care in cystic fibrosis. Lancet 2023; 402:1171-1184. [PMID: 37699418 DOI: 10.1016/s0140-6736(23)01609-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/17/2023] [Accepted: 07/31/2023] [Indexed: 09/14/2023]
Abstract
Following discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 1989 and subsequent elucidation of the varied CFTR protein abnormalities that result, a new era of cystic fibrosis management has emerged-one in which scientific principles translated from the bench to the bedside have enabled us to potentially treat the basic defect in the majority of children and adults with cystic fibrosis, with a resultant burgeoning adult cystic fibrosis population. However, the long-term effects of these therapies on the multiple manifestations of cystic fibrosis are still under investigation. Understanding the effects of modulators in populations excluded from clinical trials is also crucial. Furthermore, establishing appropriate disease measures to assess efficacy in the youngest potential trial participants and in those whose post-modulator lung function is in the typical range for people without chronic lung disease is essential for continued drug development. Finally, recognising that a health outcome gap has been created for some people and widened for others who are not eligible for, cannot tolerate, or do not have access to modulators is important.
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Affiliation(s)
- Jennifer L Taylor-Cousar
- Division of Pulmonary, Critical Care and Sleep Medicine, National Jewish Health, Denver, CO, USA; Division of Pediatric Pulmonary Medicine, National Jewish Health, Denver, CO, USA; Division of Pulmonary Sciences and Critical Care Medicine, Anschutz Medical Campus, University of Colorado, Aurora, CO, USA.
| | - Paul D Robinson
- Department of Respiratory Medicine, Queensland Children's Hospital, Brisbane, QLD, Australia; Children's Health and Environment Program, Child Health Research Centre, University of Queensland, Brisbane, QLD, Australia
| | - Michal Shteinberg
- Pulmonology Institute and CF Center, Carmel Medical Center, Haifa, Israel; B Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Damian G Downey
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, UK
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4
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Tümmler B. Post-approval studies with the CFTR modulators Elexacaftor-Tezacaftor—Ivacaftor. Front Pharmacol 2023; 14:1158207. [PMID: 37025483 PMCID: PMC10072268 DOI: 10.3389/fphar.2023.1158207] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/07/2023] [Indexed: 03/31/2023] Open
Abstract
Triple combination therapy with the CFTR modulators elexacaftor (ELX), tezacaftor (TEZ) and ivacaftor (IVA) has been qualified as a game changer in cystic fibrosis (CF). We provide an overview of the body of literature on ELX/TEZ/IVA published between November 2019 and February 2023 after approval by the regulators. Recombinant ELX/TEZ/IVA-bound Phe508del CFTR exhibits a wild type conformationin vitro, but in patient’s tissue a CFTR glyoisoform is synthesized that is distinct from the wild type and Phe508del isoforms. ELX/TEZ/IVA therapy improved the quality of life of people with CF in the real-life setting irrespective of their anthropometry and lung function at baseline. ELX/TEZ/IVA improved sinonasal and abdominal disease, lung function and morphology, airway microbiology and the basic defect of impaired epithelial chloride and bicarbonate transport. Pregnancy rates were increasing in women with CF. Side effects of mental status changes deserve particular attention in the future.
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Affiliation(s)
- Burkhard Tümmler
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
- *Correspondence: Burkhard Tümmler,
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5
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Prins S, Corradi V, Sheppard DN, Tieleman DP, Vergani P. Can two wrongs make a right? F508del-CFTR ion channel rescue by second-site mutations in its transmembrane domains. J Biol Chem 2022; 298:101615. [PMID: 35065958 PMCID: PMC8861112 DOI: 10.1016/j.jbc.2022.101615] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 11/20/2022] Open
Abstract
Deletion of phenylalanine 508 (F508del) in the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is the most common cause of cystic fibrosis. The F508 residue is located on nucleotide-binding domain 1 (NBD1) in contact with the cytosolic extensions of the transmembrane helices, in particular intracellular loop 4 (ICL4). To investigate how absence of F508 at this interface impacts the CFTR protein, we carried out a mutagenesis scan of ICL4 by introducing second-site mutations at 11 positions in cis with F508del. Using an image-based fluorescence assay, we measured how each mutation affected membrane proximity and ion-channel function. The scan strongly validated the effectiveness of R1070W at rescuing F508del defects. Molecular dynamics simulations highlighted two features characterizing the ICL4/NBD1 interface of F508del/R1070W-CFTR: flexibility, with frequent transient formation of interdomain hydrogen bonds, and loosely stacked aromatic sidechains (F1068, R1070W, and F1074, mimicking F1068, F508, and F1074 in WT CFTR). F508del-CFTR displayed a distorted aromatic stack, with F1068 displaced toward the space vacated by F508, while in F508del/R1070F-CFTR, which largely retained F508del defects, R1070F could not form hydrogen bonds and the interface was less flexible. Other ICL4 second-site mutations which partially rescued F508del-CFTR included F1068M and F1074M. Methionine side chains allow hydrophobic interactions without the steric rigidity of aromatic rings, possibly conferring flexibility to accommodate the absence of F508 and retain a dynamic interface. These studies highlight how both hydrophobic interactions and conformational flexibility might be important at the ICL4/NBD1 interface, suggesting possible structural underpinnings of F508del-induced dysfunction.
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Affiliation(s)
- Stella Prins
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Valentina Corradi
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - D Peter Tieleman
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, Calgary, Alberta, Canada
| | - Paola Vergani
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
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6
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Xia S, Bozóky Z, Di Paola M, Laselva O, Ahmadi S, Jiang JX, Pitstick AL, Jiang C, Rotin D, Mayhew CN, Jones NL, Bear CE. High-Throughput Functional Analysis of CFTR and Other Apically Localized Proteins in iPSC-Derived Human Intestinal Organoids. Cells 2021; 10:cells10123419. [PMID: 34943927 PMCID: PMC8699884 DOI: 10.3390/cells10123419] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/26/2021] [Accepted: 11/30/2021] [Indexed: 01/15/2023] Open
Abstract
Induced Pluripotent Stem Cells (iPSCs) can be differentiated into epithelial organoids that recapitulate the relevant context for CFTR and enable testing of therapies targeting Cystic Fibrosis (CF)-causing mutant proteins. However, to date, CF-iPSC-derived organoids have only been used to study pharmacological modulation of mutant CFTR channel activity and not the activity of other disease-relevant membrane protein constituents. In the current work, we describe a high-throughput, fluorescence-based assay of CFTR channel activity in iPSC-derived intestinal organoids and describe how this method can be adapted to study other apical membrane proteins. Specifically, we show how this assay can be employed to study CFTR and ENaC channels and an electrogenic acid transporter in the same iPSC-derived intestinal tissue. This phenotypic platform promises to expand CF therapy discovery to include strategies that target multiple determinants of epithelial fluid transport.
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Affiliation(s)
- Sunny Xia
- Molecular Medicine, Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada; (S.X.); (Z.B.); (O.L.); (J.X.J.)
- Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; (C.J.); (D.R.); (N.L.J.)
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada;
| | - Zoltán Bozóky
- Molecular Medicine, Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada; (S.X.); (Z.B.); (O.L.); (J.X.J.)
| | - Michelle Di Paola
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada;
| | - Onofrio Laselva
- Molecular Medicine, Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada; (S.X.); (Z.B.); (O.L.); (J.X.J.)
- Department of Medical and Surgical Sciences, University of Foggia, 71122 Foggia, Italy
| | - Saumel Ahmadi
- Department of Neurology, Washington University in St. Louis, St. Louis, MO 63110, USA;
| | - Jia Xin Jiang
- Molecular Medicine, Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada; (S.X.); (Z.B.); (O.L.); (J.X.J.)
| | - Amy L. Pitstick
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA; (A.L.P.); (C.N.M.)
| | - Chong Jiang
- Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; (C.J.); (D.R.); (N.L.J.)
| | - Daniela Rotin
- Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; (C.J.); (D.R.); (N.L.J.)
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Christopher N. Mayhew
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA; (A.L.P.); (C.N.M.)
| | - Nicola L. Jones
- Cell Biology, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; (C.J.); (D.R.); (N.L.J.)
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada;
- Department of Paediatrics, University of Toronto, Toronto, ON M5G 0A4, Canada
| | - Christine E. Bear
- Molecular Medicine, Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada; (S.X.); (Z.B.); (O.L.); (J.X.J.)
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 0A4, Canada
- Correspondence:
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7
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Liu J, Berg AP, Wang Y, Jantarajit W, Sutcliffe KJ, Stevens EB, Cao L, Pregel MJ, Sheppard DN. A small molecule CFTR potentiator restores ATP-dependent channel gating to the cystic fibrosis mutant G551D-CFTR. Br J Pharmacol 2021; 179:1319-1337. [PMID: 34644413 PMCID: PMC9304199 DOI: 10.1111/bph.15709] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 08/30/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Cystic fibrosis transmembrane conductance regulator (CFTR) potentiators are small molecules developed to treat the genetic disease cystic fibrosis (CF). They interact directly with CFTR Cl- channels at the plasma membrane to enhance channel gating. Here, we investigate the action of a new CFTR potentiator, CP-628006 with a distinct chemical structure. EXPERIMENTAL APPROACH Using electrophysiological assays with CFTR-expressing heterologous cells and CF patient-derived human bronchial epithelial (hBE) cells, we compared the effects of CP-628006 with the marketed CFTR potentiator ivacaftor. KEY RESULTS CP-628006 efficaciously potentiated CFTR function in epithelia from cultured hBE cells. Its effects on the predominant CFTR variant F508del-CFTR were larger than those with the gating variant G551D-CFTR. In excised inside-out membrane patches, CP-628006 potentiated wild-type, F508del- and G551D-CFTR by increasing the frequency and duration of channel openings. CP-628006 increased the affinity and efficacy of F508del-CFTR gating by ATP. In these respects, CP-628006 behaved like ivacaftor. CP-628006 also demonstrated notable differences with ivacaftor. Its potency and efficacy were lower than those of ivacaftor. CP-628006 conferred ATP-dependent gating on G551D-CFTR, whereas the action of ivacaftor was ATP-independent. For G551D-CFTR, but not F508del-CFTR, the action of CP-628006 plus ivacaftor was greater than ivacaftor alone. CP-628006 delayed, but did not prevent, the deactivation of F508del-CFTR at the plasma membrane, whereas ivacaftor accentuated F508del-CFTR deactivation. CONCLUSIONS AND IMPLICATIONS CP-628006 has distinct effects compared to ivacaftor, suggesting a different mechanism of CFTR potentiation. The emergence of CFTR potentiators with diverse modes of action makes therapy with combinations of potentiators a possibility.
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Affiliation(s)
- Jia Liu
- Neuroscience and Pain Research Unit, Pfizer Inc., Granta Park, Great Abington, Cambridge, UK.,School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
| | - Allison P Berg
- Rare Disease Research Unit, Pfizer Inc., Cambridge, MA, USA
| | - Yiting Wang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
| | - Walailak Jantarajit
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK.,Center of Calcium and Bone Research and Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Katy J Sutcliffe
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
| | - Edward B Stevens
- Neuroscience and Pain Research Unit, Pfizer Inc., Granta Park, Great Abington, Cambridge, UK
| | - Lishuang Cao
- Neuroscience and Pain Research Unit, Pfizer Inc., Granta Park, Great Abington, Cambridge, UK
| | - Marko J Pregel
- Rare Disease Research Unit, Pfizer Inc., Cambridge, MA, USA
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, UK
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8
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Yeh HI, Yu YC, Kuo PL, Tsai CK, Huang HT, Hwang TC. Functional stability of CFTR depends on tight binding of ATP at its degenerate ATP-binding site. J Physiol 2021; 599:4625-4642. [PMID: 34411298 DOI: 10.1113/jp281933] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 08/13/2021] [Indexed: 01/28/2023] Open
Abstract
Opening of the cystic fibrosis transmembrane conductance regulator (CFTR) channel is coupled to the motion of its two nucleotide-binding domains: they form a heterodimer sandwiching two functionally distinct ATP-binding sites (sites 1 and 2). While active ATP hydrolysis in site 2 triggers rapid channel closure, the functional role of stable ATP binding in the catalysis-incompetent (or degenerate) site 1, a feature conserved in many other ATP-binding cassette (ABC) transporter proteins, remains elusive. Here, we found that CFTR loses its prompt responsiveness to ATP after the channel is devoid of ATP for tens to hundreds of seconds. Mutants with weakened ATP binding in site 1 and the most prevalent disease-causing mutation, F508del, are more vulnerable to ATP depletion. In contrast, strengthening ligand binding in site 1 with N6 -(2-phenylethyl)-ATP, a high-affinity ATP analogue, or abolishing ATP hydrolysis in site 2 by the mutation D1370N, helps sustain a durable function of the otherwise unstable mutant channels. Thus, tight binding of ATP in the degenerate ATP-binding site is crucial to the functional stability of CFTR. Small molecules targeting site 1 may bear therapeutic potential to overcome the membrane instability of F508del-CFTR. KEY POINTS: During evolution, many ATP-binding cassette transporters - including the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, whose dysfunction causes cystic fibrosis (CF) - lose the ability to hydrolyse ATP in one of the two ATP-binding sites. Here we show that tight ATP binding at this degenerate site in CFTR is central for maintaining the stable, robust function of normal CFTR. We also demonstrate that membrane instability of the most common CF-causing mutant, F508del-CFTR, can be rescued by strengthening ATP binding at CFTR's degenerate site. Our data thus explain an evolutionary puzzle and offer a potential therapeutic strategy for CF.
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Affiliation(s)
- Han-I Yeh
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, Columbia, MO, 65211, USA.,Department of Pharmacology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ying-Chun Yu
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Pei-Lun Kuo
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chun-Kuang Tsai
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Hsin-Tuan Huang
- School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, Columbia, MO, 65211, USA.,Department of Pharmacology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
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9
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Prins S, Langron E, Hastings C, Hill EJ, Stefan AC, Griffin LD, Vergani P. Fluorescence assay for simultaneous quantification of CFTR ion-channel function and plasma membrane proximity. J Biol Chem 2020; 295:16529-16544. [PMID: 32934006 PMCID: PMC7864054 DOI: 10.1074/jbc.ra120.014061] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/21/2020] [Indexed: 11/21/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a plasma membrane anion channel that plays a key role in controlling transepithelial fluid movement. Excessive activation results in intestinal fluid loss during secretory diarrheas, whereas CFTR mutations underlie cystic fibrosis (CF). Anion permeability depends both on how well CFTR channels work (permeation/gating) and on how many are present at the membrane. Recently, treatments with two drug classes targeting CFTR-one boosting ion-channel function (potentiators) and the other increasing plasma membrane density (correctors)-have provided significant health benefits to CF patients. Here, we present an image-based fluorescence assay that can rapidly and simultaneously estimate both CFTR ion-channel function and the protein's proximity to the membrane. We monitor F508del-CFTR, the most common CF-causing variant, and confirm rescue by low temperature, CFTR-targeting drugs and second-site revertant mutation R1070W. In addition, we characterize a panel of 62 CF-causing mutations. Our measurements correlate well with published data (electrophysiology and biochemistry), further confirming validity of the assay. Finally, we profile effects of acute treatment with approved potentiator drug VX-770 on the rare-mutation panel. Mapping the potentiation profile on CFTR structures raises mechanistic hypotheses on drug action, suggesting that VX-770 might allow an open-channel conformation with an alternative arrangement of domain interfaces. The assay is a valuable tool for investigation of CFTR molecular mechanisms, allowing accurate inferences on gating/permeation. In addition, by providing a two-dimensional characterization of the CFTR protein, it could better inform development of single-drug and precision therapies addressing the root cause of CF disease.
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Affiliation(s)
- Stella Prins
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Emily Langron
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Cato Hastings
- CoMPLEX, University College London, London, United Kingdom
| | - Emily J Hill
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom
| | - Andra C Stefan
- Natural Sciences, University College London, London, United Kingdom
| | | | - Paola Vergani
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, United Kingdom.
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10
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Oliver KE, Rauscher R, Mijnders M, Wang W, Wolpert MJ, Maya J, Sabusap CM, Kesterson RA, Kirk KL, Rab A, Braakman I, Hong JS, Hartman JL, Ignatova Z, Sorscher EJ. Slowing ribosome velocity restores folding and function of mutant CFTR. J Clin Invest 2020; 129:5236-5253. [PMID: 31657788 DOI: 10.1172/jci124282] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 08/28/2019] [Indexed: 12/19/2022] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR), with approximately 90% of patients harboring at least one copy of the disease-associated variant F508del. We utilized a yeast phenomic system to identify genetic modifiers of F508del-CFTR biogenesis, from which ribosomal protein L12 (RPL12/uL11) emerged as a molecular target. In the present study, we investigated mechanism(s) by which suppression of RPL12 rescues F508del protein synthesis and activity. Using ribosome profiling, we found that rates of translation initiation and elongation were markedly slowed by RPL12 silencing. However, proteolytic stability and patch-clamp assays revealed RPL12 depletion significantly increased F508del-CFTR steady-state expression, interdomain assembly, and baseline open-channel probability. We next evaluated whether Rpl12-corrected F508del-CFTR could be further enhanced with concomitant pharmacologic repair (e.g., using clinically approved modulators lumacaftor and tezacaftor) and demonstrated additivity of these treatments. Rpl12 knockdown also partially restored maturation of specific CFTR variants in addition to F508del, and WT Cftr biogenesis was enhanced in the pancreas, colon, and ileum of Rpl12 haplosufficient mice. Modulation of ribosome velocity therefore represents a robust method for understanding both CF pathogenesis and therapeutic response.
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Affiliation(s)
| | - Robert Rauscher
- Institute for Biochemistry & Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Marjolein Mijnders
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Wei Wang
- Gregory Fleming James Cystic Fibrosis Research Center and
| | | | - Jessica Maya
- Gregory Fleming James Cystic Fibrosis Research Center and
| | | | - Robert A Kesterson
- Department of Genetics, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA
| | - Kevin L Kirk
- Gregory Fleming James Cystic Fibrosis Research Center and
| | - Andras Rab
- Emory University School of Medicine, Atlanta, Georgia, USA
| | - Ineke Braakman
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Jeong S Hong
- Emory University School of Medicine, Atlanta, Georgia, USA
| | - John L Hartman
- Gregory Fleming James Cystic Fibrosis Research Center and.,Department of Genetics, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA
| | - Zoya Ignatova
- Institute for Biochemistry & Molecular Biology, University of Hamburg, Hamburg, Germany
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11
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Singh AK, Fan Y, Balut C, Alani S, Manelli AM, Swensen AM, Jia Y, Neelands TR, Vortherms TA, Liu B, Searle XB, Wang X, Gao W, Hwang TC, Ren HY, Cyr D, Kym PR, Conrath K, Tse C. Biological Characterization of F508delCFTR Protein Processing by the CFTR Corrector ABBV-2222/GLPG2222. J Pharmacol Exp Ther 2020; 372:107-118. [PMID: 31732698 PMCID: PMC11047061 DOI: 10.1124/jpet.119.261800] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/29/2019] [Indexed: 12/11/2022] Open
Abstract
Cystic fibrosis (CF) is the most common monogenic autosomal recessive disease in Caucasians caused by pathogenic mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene (CFTR). Significant small molecule therapeutic advances over the past two decades have been made to target the defective CFTR protein and enhance its function. To address the most prevalent defect of the defective CFTR protein (i.e., F508del mutation) in CF, two biomolecular activities are required, namely, correctors to increase the amount of properly folded F508delCFTR levels at the cell surface and potentiators to allow the effective opening, i.e., function of the F508delCFTR channel. Combined, these activities enhance chloride ion transport yielding improved hydration of the lung surface and subsequent restoration of mucociliary clearance. To enhance clinical benefits to CF patients, a complementary triple combination therapy consisting of two corrector molecules, type 1 (C1) and type 2, with additive mechanisms along with a potentiator are being investigated in the clinic for maximum restoration of mutated CFTR function. We report the identification and in vitro biologic characterization of ABBV-2222/GLPG2222 (4-[(2R,4R)-4-({[1-(2,2-difluoro-1,3-benzodioxol-5-yl)cyclopropyl]carbonyl}amino)-7-(difluoromethoxy)-3,4-dihydro-2H-chromen-2-yl]benzoic acid),-a novel, potent, and orally bioavailable C1 corrector developed by AbbVie-Galapagos and currently in clinical trials-which exhibits substantial improvements over the existing C1 correctors. This includes improvements in potency and drug-drug interaction (DDI) compared with 3-(6-(1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)cyclopropanecarboxamido)-3-methylpyridin-2-yl)benzoic acid (VX-809, Lumacaftor) and improvements in potency and efficacy compared with 1-(2,2-difluoro-1,3-benzodioxol-5-yl)-N-[1-[(2R)-2,3-dihydroxypropyl]-6-fluoro-2-(1-hydroxy-2-methylpropan-2-yl)indol-5-yl]cyclopropane-1-carboxamide (VX-661, Tezacaftor). ABBV-2222/GLPG2222 exhibits potent in vitro functional activity in primary patient cells harboring F508del/F508del CFTR with an EC50 value <10 nM. SIGNIFICANCE STATEMENT: To address the most prevalent defect of the defective CFTR protein (i.e., F508del mutation) in cystic fibrosis, AbbVie-Galapagos has developed ABBV-2222/GLPG2222, a novel, potent, and orally bioavailable C1 corrector of this protein. ABBV-2222/GLPG2222, which is currently in clinical trials, exhibits potent in vitro functional activity in primary patient cells harboring F508del/F508del CFTR and substantial improvements over the existing C1 correctors.
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Affiliation(s)
- Ashvani K Singh
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Yihong Fan
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Corina Balut
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Sara Alani
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Arlene M Manelli
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Andrew M Swensen
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Ying Jia
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Torben R Neelands
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Timothy A Vortherms
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Bo Liu
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Xenia B Searle
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Xueqing Wang
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Wenqing Gao
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Tzyh-Chang Hwang
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Hong Y Ren
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Douglas Cyr
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Philip R Kym
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Katja Conrath
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
| | - Chris Tse
- AbbVie Inc., iSAT, North Chicago, Illinois (A.K.S., Y.F., C.B., S.A., A.M.M., A.M.S., Y.J., T.R.N., T.A.V., B.L., X.B.S., X.W., W.G., P.R.K., C.T.); Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (T.-C.H.); Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina (H.Y.R., D.C.); and Galapagos NV, Mechelen, Belgium (K.C.)
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12
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Villamizar O, Waters SA, Scott T, Saayman S, Grepo N, Urak R, Davis A, Jaffe A, Morris KV. Targeted Activation of Cystic Fibrosis Transmembrane Conductance Regulator. Mol Ther 2019; 27:1737-1748. [PMID: 31383454 PMCID: PMC6822231 DOI: 10.1016/j.ymthe.2019.07.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 06/24/2019] [Accepted: 07/03/2019] [Indexed: 01/05/2023] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. The majority of CFTR mutations result in impaired chloride channel function as only a fraction of the mutated CFTR reaches the plasma membrane. The development of a therapeutic approach that facilitates increased cell-surface expression of CFTR could prove clinically relevant. Here, we evaluate and contrast two molecular approaches to activate CFTR expression. We find that an RNA-guided nuclease null Cas9 (dCas9) fused with a tripartite activator, VP64-p65-Rta can activate endogenous CFTR in cultured human nasal epithelial cells from CF patients. We also find that targeting BGas, a long non-coding RNA involved in transcriptionally modulating CFTR expression with a gapmer, induced both strong knockdown of BGas and concordant activation of CFTR. Notably, the gapmer can be delivered to target cells when generated as electrostatic particles with recombinant HIV-Tat cell penetrating peptide (CPP), when packaged into exosomes, or when loaded into lipid nanoparticles (LNPs). Treatment of patient-derived human nasal epithelial cells containing F508del with gapmer-CPP, gapmer-exosomes, or LNPs resulted in increased expression and function of CFTR. Collectively, these observations suggest that CRISPR/dCas-VPR (CRISPR) and BGas-gapmer approaches can target and specifically activate CFTR.
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Affiliation(s)
- Olga Villamizar
- Center for Gene Therapy, City of Hope-Beckman Research Institute at the City of Hope, Duarte, CA 91010, USA
| | - Shafagh A Waters
- Faculty of Medicine, School of Women's & Children's Health, University of New South Wales (UNSW), Sydney, NSW, Australia; Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), School of Women's & Children's Health, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Tristan Scott
- Center for Gene Therapy, City of Hope-Beckman Research Institute at the City of Hope, Duarte, CA 91010, USA
| | - Sheena Saayman
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Nicole Grepo
- Center for Gene Therapy, City of Hope-Beckman Research Institute at the City of Hope, Duarte, CA 91010, USA
| | - Ryan Urak
- Center for Gene Therapy, City of Hope-Beckman Research Institute at the City of Hope, Duarte, CA 91010, USA
| | - Alicia Davis
- Center for Gene Therapy, City of Hope-Beckman Research Institute at the City of Hope, Duarte, CA 91010, USA
| | - Adam Jaffe
- Faculty of Medicine, School of Women's & Children's Health, University of New South Wales (UNSW), Sydney, NSW, Australia; Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), School of Women's & Children's Health, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia; Department of Respiratory Medicine, Sydney Children's Hospital, Sydney, NSW, Australia
| | - Kevin V Morris
- Center for Gene Therapy, City of Hope-Beckman Research Institute at the City of Hope, Duarte, CA 91010, USA.
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13
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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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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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TALEN-Mediated Gene Targeting for Cystic Fibrosis-Gene Therapy. Genes (Basel) 2019; 10:genes10010039. [PMID: 30641980 PMCID: PMC6356284 DOI: 10.3390/genes10010039] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/24/2018] [Accepted: 01/03/2019] [Indexed: 11/17/2022] Open
Abstract
Cystic fibrosis (CF) is an inherited monogenic disorder, amenable to gene-based therapies. Because CF lung disease is currently the major cause of mortality and morbidity, and the lung airway is readily accessible to gene delivery, the major CF gene therapy effort at present is directed to the lung. Although airway epithelial cells are renewed slowly, permanent gene correction through gene editing or targeting in airway stem cells is needed to perpetuate the therapeutic effect. Transcription activator-like effector nuclease (TALEN) has been utilized widely for a variety of gene editing applications. The stringent requirement for nuclease binding target sites allows for gene editing with precision. In this study, we engineered helper-dependent adenoviral (HD-Ad) vectors to deliver a pair of TALENs together with donor DNA targeting the human AAVS1 locus. With homology arms of 4 kb in length, we demonstrated precise insertion of either a LacZ reporter gene or a human cystic fibrosis transmembrane conductance regulator (CFTR) minigene (cDNA) into the target site. Using the LacZ reporter, we determined the efficiency of gene integration to be about 5%. In the CFTR vector transduced cells, we were able to detect CFTR mRNA expression using qPCR and function correction using fluorometric image plate reader (FLIPR) and iodide efflux assays. Taken together, these findings suggest a new direction for future in vitro and in vivo studies in CF gene editing.
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16
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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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17
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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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18
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19
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DeStefano S, Gees M, Hwang TC. Physiological and pharmacological characterization of the N1303K mutant CFTR. J Cyst Fibros 2018; 17:573-581. [PMID: 29887518 DOI: 10.1016/j.jcf.2018.05.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/13/2018] [Accepted: 05/21/2018] [Indexed: 11/18/2022]
Abstract
BACKGROUND N1303K, one of the common, severe disease-causing mutations in the CFTR gene, causes both defective biogenesis and gating abnormalities of the CFTR protein. The goals of the present study are to quantitatively assess the gating defects associated with the N1303K mutation and its pharmacological response to CFTR modulators including potentiators VX-770 and GLPG1837 and correctors VX-809, and VX-661. METHODS Gating behavior and pharmacological responses to CFTR potentiators were assessed using patch-clamp technique in the excised, inside-out mode. We also examined the effects of GLPG1837, VX-770, VX-809 and VX-661 on N1303K-CFTR surface expression using Western blot analysis. RESULTS Like wild-type (WT) CFTR, N1303K-CFTR channels were activated by protein kinase A-dependent phosphorylation, but the open probability (Po) of phosphorylated N1303K-CFTR was extremely low (~0.03 vs ~0.45 in WT channels). N1303K mutants showed abnormal responses to ATP analogs or mutations that disrupt ATP hydrolysis and/or dimerization of CFTR's two nucleotide-binding domains (NBDs). However, the Po of N1303K-CFTR was dramatically increased by GLPG1837 (~17-fold) and VX-770 (~8-fold). VX-809 or VX-661 enhanced N1303K-CFTR maturation by 2-3 fold, and co-treatment with GLPG1837 or VX-770 did not show any negative drug-drug interaction. CONCLUSION N1303K has a severe gating defect, reduced ATP-dependence and aberrant response to ATP analogs. These results suggest a defective function of the NBDs in N1303K-CFTR. An improvement of channel function by GLPG1837 or VX-770 and an increase of Band C protein by VX-809 or VX-661 support a therapeutic strategy of combining CFTR potentiator and corrector for patients carrying the N1303K mutation.
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Affiliation(s)
- Samantha DeStefano
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, United States; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211, United States
| | | | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, United States; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211, United States.
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20
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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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21
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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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22
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Liu J, Bihler H, Farinha CM, Awatade NT, Romão AM, Mercadante D, Cheng Y, Musisi I, Jantarajit W, Wang Y, Cai Z, Amaral MD, Mense M, Sheppard DN. Partial rescue of F508del-cystic fibrosis transmembrane conductance regulator channel gating with modest improvement of protein processing, but not stability, by a dual-acting small molecule. Br J Pharmacol 2018; 175:1017-1038. [PMID: 29318594 DOI: 10.1111/bph.14141] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 12/08/2017] [Accepted: 12/10/2017] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND AND PURPOSE Rescue of F508del-cystic fibrosis (CF) transmembrane conductance regulator (CFTR), the most common CF mutation, requires small molecules that overcome protein processing, stability and channel gating defects. Here, we investigate F508del-CFTR rescue by CFFT-004, a small molecule designed to independently correct protein processing and channel gating defects. EXPERIMENTAL APPROACH Using CFTR-expressing recombinant cells and CF patient-derived bronchial epithelial cells, we studied CFTR expression by Western blotting and channel gating and stability with the patch-clamp and Ussing chamber techniques. KEY RESULTS Chronic treatment with CFFT-004 improved modestly F508del-CFTR processing, but not its plasma membrane stability. By contrast, CFFT-004 rescued F508del-CFTR channel gating better than C18, an analogue of the clinically used CFTR corrector lumacaftor. Subsequent acute addition of CFFT-004, but not C18, potentiated F508del-CFTR channel gating. However, CFFT-004 was without effect on A561E-CFTR, a CF mutation with a comparable mechanism of CFTR dysfunction as F508del-CFTR. To investigate the mechanism of action of CFFT-004, we used F508del-CFTR revertant mutations. Potentiation by CFFT-004 was unaffected by revertant mutations, but correction was abolished by the revertant mutation G550E. These data suggest that correction, but not potentiation, by CFFT-004 might involve nucleotide-binding domain 1 of CFTR. CONCLUSIONS AND IMPLICATIONS CFFT-004 is a dual-acting small molecule with independent corrector and potentiator activities that partially rescues F508del-CFTR in recombinant cells and native airway epithelia. The limited efficacy and potency of CFFT-004 suggests that combinations of small molecules targeting different defects in F508del-CFTR might be a more effective therapeutic strategy than a single agent.
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Affiliation(s)
- Jia Liu
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Hermann Bihler
- Cystic Fibrosis Foundation Therapeutics, Lexington, MA, USA
| | - Carlos M Farinha
- Faculty of Sciences, BioISI - Biosystems and Integrative Sciences Institute, University of Lisboa, Lisboa, Portugal
| | - Nikhil T Awatade
- Faculty of Sciences, BioISI - Biosystems and Integrative Sciences Institute, University of Lisboa, Lisboa, Portugal
| | - Ana M Romão
- Faculty of Sciences, BioISI - Biosystems and Integrative Sciences Institute, University of Lisboa, Lisboa, Portugal
| | | | - Yi Cheng
- Cystic Fibrosis Foundation Therapeutics, Lexington, MA, USA
| | - Isaac Musisi
- Cystic Fibrosis Foundation Therapeutics, Lexington, MA, USA
| | - Walailak Jantarajit
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.,Center of Calcium and Bone Research and Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Yiting Wang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Zhiwei Cai
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Margarida D Amaral
- Faculty of Sciences, BioISI - Biosystems and Integrative Sciences Institute, University of Lisboa, Lisboa, Portugal
| | - Martin Mense
- Cystic Fibrosis Foundation Therapeutics, Lexington, MA, USA
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
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23
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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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24
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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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25
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Sorum B, Töröcsik B, Csanády L. Asymmetry of movements in CFTR's two ATP sites during pore opening serves their distinct functions. eLife 2017; 6:29013. [PMID: 28944753 PMCID: PMC5626490 DOI: 10.7554/elife.29013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 09/25/2017] [Indexed: 11/13/2022] Open
Abstract
CFTR, the chloride channel mutated in cystic fibrosis (CF) patients, is opened by ATP binding to two cytosolic nucleotide binding domains (NBDs), but pore-domain mutations may also impair gating. ATP-bound NBDs dimerize occluding two nucleotides at interfacial binding sites; one site hydrolyzes ATP, the other is inactive. The pore opens upon tightening, and closes upon disengagement, of the catalytic site following ATP hydrolysis. Extent, timing, and role of non-catalytic-site movements are unknown. Here we exploit equilibrium gating of a hydrolysis-deficient mutant and apply Φ value analysis to compare timing of opening-associated movements at multiple locations, from the cytoplasmic ATP sites to the extracellular surface. Marked asynchrony of motion in the two ATP sites reveals their distinct roles in channel gating. The results clarify the molecular mechanisms of functional cross-talk between canonical and degenerate ATP sites in asymmetric ABC proteins, and of the gating defects caused by two common CF mutations.
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Affiliation(s)
- Ben Sorum
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary
| | - Beáta Töröcsik
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.,MTA-SE Ion Channel Research Group, Semmelweis University, Budapest, Hungary
| | - László Csanády
- Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary.,MTA-SE Ion Channel Research Group, Semmelweis University, Budapest, Hungary
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26
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Bulloch MN, Hanna C, Giovane R. Lumacaftor/ivacaftor, a novel agent for the treatment of cystic fibrosis patients who are homozygous for the F580del CFTR mutation. Expert Rev Clin Pharmacol 2017; 10:1055-1072. [PMID: 28891346 DOI: 10.1080/17512433.2017.1378094] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Cystic Fibrosis (CF) is an autosomal recessive disease affecting up to 90,000 people worldwide. Approximately 73% of patients are homozygous for the F508del cystic fibrosis transmembrane conductance regulator [CFTR] mutation. Traditionally treatment has only included supportive care. Therefore, there is a need for safe and effective novel therapies targeting the underlying molecular defects seen with CF. Areas covered: In 2016, the Food and Drug Administration and the European Commission approved LUM/IVA (Orkambi), a CFTR modulator that includes both a CFTR corrector and potentiator, for CF patients homozygous for the F508del CFTR mutation. This article reviews the pharmacologic features, clinical efficacy, and safety of LUM/IVA and summarize the available pre-clinical and clinical data of LUM/IVA use. Expert commentary: LUM/IVA showed modest, but significant improvements from baseline in percent predicted FEV1 (ppFEV1) as well as a reduction in pulmonary exacerbations by 35% It was shown to be safe for short- and long-term use. Currently, LUM/IVA is the only oral agent in its class available and represents a milestone the development of therapies for the management of CF. Nonetheless, pharmacoeconomic data are necessary to justify its high cost before is use becomes standard of care.
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Affiliation(s)
- Marilyn N Bulloch
- a Harrison School of Pharmacy , Auburn University , Auburn , AL , USA.,b College of Community Health Sciences , University of Alabama , Tuscaloosa , AL , USA
| | - Cameron Hanna
- a Harrison School of Pharmacy , Auburn University , Auburn , AL , USA
| | - Richard Giovane
- c Harrison School of Pharmacy , Auburn University , Tuscaloosa , AL , USA
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27
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Rafeeq MM, Murad HAS. Cystic fibrosis: current therapeutic targets and future approaches. J Transl Med 2017; 15:84. [PMID: 28449677 PMCID: PMC5408469 DOI: 10.1186/s12967-017-1193-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/23/2017] [Indexed: 01/01/2023] Open
Abstract
Objectives Study of currently approved drugs and exploration of future clinical development pipeline therapeutics for cystic fibrosis, and possible limitations in their use. Methods Extensive literature search using individual and a combination of key words related to cystic fibrosis therapeutics. Key findings Cystic fibrosis is an autosomal recessive disorder due to mutations in CFTR gene leading to abnormality of chloride channels in mucus and sweat producing cells. Respiratory system and GIT are primarily involved but eventually multiple organs are affected leading to life threatening complications. Management requires drug therapy, extensive physiotherapy and nutritional support. Previously, the focus was on symptomatic improvement and complication prevention but recently the protein rectifiers are being studied which are claimed to correct underlying structural and functional abnormalities. Some improvement is observed by the corrector drugs. Other promising approaches are gene therapy, targeting of cellular interactomes, and newer drugs for symptomatic improvement. Conclusions The treatment has a long way to go as most of the existing therapeutics is for older children. Other limiting factors include mutation class, genetic profile, drug interactions, adverse effects, and cost. Novel approaches like gene transfer/gene editing, disease modeling and search for alternative targets are warranted.
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Affiliation(s)
- Misbahuddin M Rafeeq
- Department of Pharmacology, Faculty of Medicine, King Abdulaziz University, Rabigh Campus, Jeddah, 21589, Saudi Arabia.
| | - Hussam Aly Sayed Murad
- Department of Pharmacology, Faculty of Medicine, King Abdulaziz University, Rabigh Campus, Jeddah, 21589, Saudi Arabia.,Department of Pharmacology, Faculty of Medicine, Ain Shams University, Cairo, 11562, Egypt
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28
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Abstract
Pulmonary disease is the major cause of morbidity and mortality in patients with cystic fibrosis, a disease caused by mutations in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. Heterogeneity in CFTR genotype–phenotype relationships in affected individuals plus the escalation of drug discovery targeting specific mutations highlights the need to develop robust in vitro platforms with which to stratify therapeutic options using relevant tissue. Toward this goal, we adapted a fluorescence plate reader assay of apical CFTR-mediated chloride conductance to enable profiling of a panel of modulators on primary nasal epithelial cultures derived from patients bearing different CFTR mutations. This platform faithfully recapitulated patient-specific responses previously observed in the “gold-standard” but relatively low-throughput Ussing chamber. Moreover, using this approach, we identified a novel strategy with which to augment the response to an approved drug in specific patients. In proof of concept studies, we also validated the use of this platform in measuring drug responses in lung cultures differentiated from cystic fibrosis iPS cells. Taken together, we show that this medium throughput assay of CFTR activity has the potential to stratify cystic fibrosis patient-specific responses to approved drugs and investigational compounds in vitro in primary and iPS cell-derived airway cultures. A new method for evaluating drug responses in patient-derived respiratory tissue promises to help determine the best treatment for each patient with cystic fibrosis (CF). CF patients are highly susceptible to lung infections due to the build-up of thick mucus in the airways. Over 2000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene have been identified in patients with CF, which partly explains their varied response to treatment. Saumel Ahmadi, Christine E. Bear, and colleagues at the Hospital for Sick Children in Toronto developed a fluorescence-based method for measuring improvements in mutant CFTR function in patient-derived nasal and induced pluripotent stem cell-derived lung tissue. This method enables comparison of approved and investigational drugs on airway cells from each individual patient and in the longer term will accelerate the development of personalized therapeutic strategies.
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29
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Meng X, Wang Y, Wang X, Wrennall JA, Rimington TL, Li H, Cai Z, Ford RC, Sheppard DN. Two Small Molecules Restore Stability to a Subpopulation of the Cystic Fibrosis Transmembrane Conductance Regulator with the Predominant Disease-causing Mutation. J Biol Chem 2017; 292:3706-3719. [PMID: 28087700 PMCID: PMC5339754 DOI: 10.1074/jbc.m116.751537] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 01/12/2017] [Indexed: 12/17/2022] Open
Abstract
Cystic fibrosis (CF) is caused by mutations that disrupt the plasma membrane expression, stability, and function of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Two small molecules, the CFTR corrector lumacaftor and the potentiator ivacaftor, are now used clinically to treat CF, although some studies suggest that they have counteracting effects on CFTR stability. Here, we investigated the impact of these compounds on the instability of F508del-CFTR, the most common CF mutation. To study individual CFTR Cl- channels, we performed single-channel recording, whereas to assess entire CFTR populations, we used purified CFTR proteins and macroscopic CFTR Cl- currents. At 37 °C, low temperature-rescued F508del-CFTR more rapidly lost function in cell-free membrane patches and showed altered channel gating and current flow through open channels. Compared with purified wild-type CFTR, the full-length F508del-CFTR was about 10 °C less thermostable. Lumacaftor partially stabilized purified full-length F508del-CFTR and slightly delayed deactivation of individual F508del-CFTR Cl- channels. By contrast, ivacaftor further destabilized full-length F508del-CFTR and accelerated channel deactivation. Chronic (prolonged) co-incubation of F508del-CFTR-expressing cells with lumacaftor and ivacaftor deactivated macroscopic F508del-CFTR Cl- currents. However, at the single-channel level, chronic co-incubation greatly increased F508del-CFTR channel activity and temporal stability in most, but not all, cell-free membrane patches. We conclude that chronic lumacaftor and ivacaftor co-treatment restores stability in a small subpopulation of F508del-CFTR Cl- channels but that the majority remain destabilized. A fuller understanding of these effects and the characterization of the small F508del-CFTR subpopulation might be crucial for CF therapy development.
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Affiliation(s)
- Xin Meng
- From the Faculty of Biology, Medicine and Health, School of Biological Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PL, United Kingdom and
| | - Yiting Wang
- the School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Xiaomeng Wang
- From the Faculty of Biology, Medicine and Health, School of Biological Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PL, United Kingdom and
| | - Joe A Wrennall
- the School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Tracy L Rimington
- From the Faculty of Biology, Medicine and Health, School of Biological Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PL, United Kingdom and
| | - Hongyu Li
- the School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Zhiwei Cai
- the School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
| | - Robert C Ford
- From the Faculty of Biology, Medicine and Health, School of Biological Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PL, United Kingdom and
| | - David N Sheppard
- the School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
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Zhang Z, Baksh MM, Finn MG, Heidary DK, Richards CI. Direct Measurement of Trafficking of the Cystic Fibrosis Transmembrane Conductance Regulator to the Cell Surface and Binding to a Chemical Chaperone. Biochemistry 2016; 56:240-249. [PMID: 28001373 DOI: 10.1021/acs.biochem.6b00853] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) result in the disease cystic fibrosis. Deletion of Phe508, the most prevalent mutation associated with this disease, disrupts trafficking of the protein. Small molecule correctors yield moderate improvements in the trafficking of ΔF508-CFTR to the plasma membrane. It is currently not known if correctors increase the level of trafficking through improved cargo loading of transport vesicles or through direct binding to CFTR. Real-time measurements of trafficking were utilized to identify the mechanistic details of chemical, biochemical, and thermal factors that impact CFTR correction, using the corrector molecule VX-809, a secondary mutation (I539T), and low-temperature conditions. Each individually improved trafficking of ΔF508-CFTR to approximately 10% of wild-type levels. The combination of VX-809 with either low temperature or the I539T mutation increased the amount of CFTR on the plasma membrane to nearly 40%, indicating synergistic activity. The number of vesicles reaching the surface was significantly altered; however, the amount of channel in each vesicle remained the same. Direct binding measurements of VX-809 in native membranes using backscattering interferometry indicate tight binding to CFTR, which occurred in a manner independent of mutation. The similar values obtained for all forms of the channel indicate that the binding site is not compromised or enhanced by these mutations.
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Affiliation(s)
- Zhihui Zhang
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - Michael M Baksh
- Department of Chemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - M G Finn
- Department of Chemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - David K Heidary
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - Christopher I Richards
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
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31
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Schneider EK, Reyes-Ortega F, Li J, Velkov T. Can Cystic Fibrosis Patients Finally Catch a Breath With Lumacaftor/Ivacaftor? Clin Pharmacol Ther 2016; 101:130-141. [PMID: 27804127 DOI: 10.1002/cpt.548] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/24/2016] [Accepted: 10/25/2016] [Indexed: 12/13/2022]
Abstract
Cystic fibrosis (CF) is a life-limiting disease caused by defective or deficient cystic fibrosis transmembrane conductance regulator (CFTR) activity. The recent US Food and Drug Administration (FDA) approval of lumacaftor combined with ivacaftor (Orkambi) targets patients with the F508del-CFTR. The question remains: Is this breakthrough combination therapy the "magic-bullet" cure for the vast majority of patients with CF? This review covers the contemporary clinical and scientific knowledge-base for lumacaftor/ivacaftor and highlights the emerging issues from recent conflicting literature reports.
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Affiliation(s)
- E K Schneider
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences; Monash University, Parkville, Victoria, Australia
| | - F Reyes-Ortega
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences; Monash University, Parkville, Victoria, Australia
| | - J Li
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences; Monash University, Parkville, Victoria, Australia.,Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - T Velkov
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences; Monash University, Parkville, Victoria, Australia
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32
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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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Spielberg DR, Clancy JP. Cystic Fibrosis and Its Management Through Established and Emerging Therapies. Annu Rev Genomics Hum Genet 2016; 17:155-75. [PMID: 26905785 DOI: 10.1146/annurev-genom-090314-050024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cystic fibrosis (CF) is the most common life-shortening autosomal recessive disorder in the Caucasian population and occurs in many other ethnicities worldwide. The daily treatment burden is substantial for CF patients even when they are well, with numerous pharmacologic and physical therapies targeting lung disease requiring the greatest time commitment. CF treatments continue to advance with greater understanding of factors influencing long-term morbidity and mortality. In recent years, in-depth understanding of genetic and protein structure-function relationships has led to the introduction of targeted therapies for patients with specific CF genotypes. With these advances, CF has become a model of personalized or precision medicine. The near future will see greater access to targeted therapies for most patients carrying common mutations, which will mandate individualized bench-to-bedside methodologies for those with rare genotypes.
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Affiliation(s)
- David R Spielberg
- Department of Pediatrics, Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio 45229; ,
| | - John P Clancy
- Department of Pediatrics, Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio 45229; ,
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35
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Savant AP, McColley SA. 2014 year in review: Cystic fibrosis. Pediatr Pulmonol 2015; 50:1147-56. [PMID: 26347000 DOI: 10.1002/ppul.23309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 07/26/2015] [Accepted: 08/22/2015] [Indexed: 12/23/2022]
Abstract
In this article, we highlight cystic fibrosis (CF) research published in Pediatric Pulmonology during 2014, as well as related articles published in other journals.
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Affiliation(s)
- Adrienne P Savant
- Division of Pulmonary Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Illinois.,Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Susanna A McColley
- Division of Pulmonary Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Illinois.,Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois.,Stanley Manne Children's Research Institute, Illinois
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36
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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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37
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Bali V, Lazrak A, Guroji P, Fu L, Matalon S, Bebok Z. A synonymous codon change alters the drug sensitivity of ΔF508 cystic fibrosis transmembrane conductance regulator. FASEB J 2015; 30:201-13. [PMID: 26336913 DOI: 10.1096/fj.15-273714] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/31/2015] [Indexed: 11/11/2022]
Abstract
Synonymous mutations, such as I507-ATC→ATT, in deletion of Phe508 in cystic fibrosis transmembrane conductance regulator (ΔF508 CFTR), the most frequent disease-associated mutant of CFTR, may affect protein biogenesis, structure, and function and contribute to an altered disease phenotype. Small-molecule drugs are being developed to correct ΔF508 CFTR. To understand correction mechanisms and the consequences of synonymous mutations, we analyzed the effect of mechanistically distinct correctors, corrector 4a (C4) and lumacaftor (VX-809), on I507-ATT and I507-ATC ΔF508 CFTR biogenesis and function. C4 stabilized I507-ATT ΔF508 CFTR band B, but without considerable biochemical and functional correction. VX-809 biochemically corrected ∼10% of both of the variants, leading to stable, forskolin+3-isobutyl-1-methylxanthine (IBMX)-activated whole-cell currents in the presence of the corrector. Omitting VX-809 during whole-cell recordings led to a spontaneous decline of the currents, suggesting posttranslational stabilization by VX-809. Treatment of cells with the C4+VX-809 combination resulted in enhanced rescue and 2-fold higher forskolin+IBMX-activated currents of both I507-ATT and I507-ATC ΔF508 CFTR, compared with VX-809 treatment alone. The lack of an effect of C4 on I507-ATC ΔF508 CFTR, but its additive effect in combination with VX-809, implies that C4 acted on VX-809-modified I507-ATC ΔF508 CFTR. Our results suggest that binding of C4 and VX-809 to ΔF508 CFTR is conformation specific and provide evidence that synonymous mutations can alter the drug sensitivity of proteins.
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Affiliation(s)
- Vedrana Bali
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ahmed Lazrak
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Purushotham Guroji
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Lianwu Fu
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sadis Matalon
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Zsuzsanna Bebok
- *Department of Cell, Developmental, and Integrative Biology, Department of Anesthesiology and Perioperative Medicine, The Lung Injury and Repair Research Center, and The Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
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39
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Affiliation(s)
- Pamela B Davis
- From Case Western Reserve University School of Medicine, Cleveland
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40
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Csanády L, Töröcsik B. Structure-activity analysis of a CFTR channel potentiator: Distinct molecular parts underlie dual gating effects. ACTA ACUST UNITED AC 2015; 144:321-36. [PMID: 25267914 PMCID: PMC4178936 DOI: 10.1085/jgp.201411246] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The head and tail regions of 5-nitro-2-(3-phenylpropylamino)benzoate increase CFTR open probability through distinct mechanisms. The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is a member of the ATP-binding cassette transporter superfamily that functions as an epithelial chloride channel. Gating of the CFTR ion conduction pore involves a conserved irreversible cyclic mechanism driven by ATP binding and hydrolysis at two cytosolic nucleotide-binding domains (NBDs): formation of an intramolecular NBD dimer that occludes two ATP molecules opens the pore, whereas dimer disruption after ATP hydrolysis closes it. CFTR dysfunction resulting from inherited mutations causes CF. The most common CF mutation, deletion of phenylalanine 508 (ΔF508), impairs both protein folding and processing and channel gating. Development of ΔF508 CFTR correctors (to increase cell surface expression) and potentiators (to enhance open probability, Po) is therefore a key focus of CF research. The practical utility of 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB), one of the most efficacious potentiators of ΔF508 CFTR identified to date, is limited by its pore-blocking side effect. NPPB-mediated stimulation of Po is unique in that it involves modulation of gating transition state stability. Although stabilization by NPPB of the transition state for pore opening enhances both the rate of channel opening and the very slow rate of nonhydrolytic closure, because of CFTR’s cyclic gating mechanism, the net effect is Po stimulation. In addition, slowing of ATP hydrolysis by NPPB delays pore closure, further enhancing Po. Here we show that NPPB stimulates gating at a site outside the pore and that these individual actions of NPPB on CFTR are fully attributable to one or the other of its two complementary molecular parts, 3-nitrobenzoate (3NB) and 3-phenylpropylamine (3PP), both of which stimulate Po: the pore-blocking 3NB selectively stabilizes the transition state for opening, whereas the nonblocking 3PP selectively slows the ATP hydrolysis step. Understanding structure–activity relationships of NPPB might prove useful for designing potent, clinically relevant CFTR potentiators.
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Affiliation(s)
- László Csanády
- Department of Medical Biochemistry and MTA-SE Ion Channel Research Group, Semmelweis University, Budapest H-1094, Hungary Department of Medical Biochemistry and MTA-SE Ion Channel Research Group, Semmelweis University, Budapest H-1094, Hungary
| | - Beáta Töröcsik
- Department of Medical Biochemistry and MTA-SE Ion Channel Research Group, Semmelweis University, Budapest H-1094, Hungary
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Yang H, Ma T. F508del-cystic fibrosis transmembrane regulator correctors for treatment of cystic fibrosis: a patent review. Expert Opin Ther Pat 2015; 25:991-1002. [PMID: 25971311 DOI: 10.1517/13543776.2015.1045878] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
INTRODUCTION Cystic fibrosis (CF) is an autosomal recessive genetic disease caused by malfunction of CF transmembrane regulator (CFTR). The deletion of a phenylalanine at residue 508 (F508del) is the most common mutation that causes cellular processing, chloride channel gating and protein stability defects in CFTR. Pharmacological modulators of F508del-CFTR, aimed at correcting the cellular processing defect (correctors) and the gating defect (potentiators) in CFTR protein, are regarded as promising therapeutic agents for CF disease. Endeavors in searching F508del-CFTR modulators have shown encouraging results, with several small-molecule compounds having entered clinical trials or even represented clinical options. AREAS COVERED This review covers the discovery of F508del-CFTR correctors described in both patents (2005 - present) and scientific literatures. EXPERT OPINION Cyclopropane carboxamide derivatives of CFTR correctors continue to dominate in this area, among which lumacaftor (a NBD1-MSD1/2 interface stabilizer) is the most promising compound and is now under the priority review by US FDA. However, the abrogation effect of ivacaftor (potentiator) on lumacaftor suggests the requirement of discovering new correctors and potentiators that can cooperate well. Integration screening for simultaneously identifying combinations of correctors (particularly NBD1 stabilizer) and potentiators should provide an alternative strategy. A recently reported natural product fraction library may be useful for the integration screening.
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Affiliation(s)
- Hong Yang
- a 1 School of Life Sciences, Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, Liaoning Normal University , Dalian 116029, P.R. China +86 411 85827085 ; +86 411 85827068 ;
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Ye L, Hu B, El-Badri F, Hudson BM, Phuan PW, Verkman AS, Tantillo DJ, Kurth MJ. ΔF508-CFTR correctors: synthesis and evaluation of thiazole-tethered imidazolones, oxazoles, oxadiazoles, and thiadiazoles. Bioorg Med Chem Lett 2014; 24:5840-5844. [PMID: 25452003 PMCID: PMC4255153 DOI: 10.1016/j.bmcl.2014.09.067] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 09/14/2014] [Accepted: 09/24/2014] [Indexed: 01/01/2023]
Abstract
The most common mutation causing cystic fibrosis (CF) is deletion of phenylalanine residue 508 in the cystic fibrosis transmembrane regulator conductance (CFTR) protein. Small molecules that are able to correct the misfolding of defective ΔF508-CFTR have considerable promise for therapy. Reported here are the design, preparation, and evaluation of five more hydrophilic bisazole analogs of previously identified bithiazole CF corrector 1. Interestingly, bisazole ΔF508-CFTR corrector activity was not increased by incorporation of more H-bond acceptors (O or N), but correlated best with the overall bisazole molecular geometry. The structure activity data, together with molecular modeling, suggested that active bisazole correctors adopt a U-shaped conformation, and that corrector activity depends on the molecule's ability to access this molecular geometry.
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Affiliation(s)
- Long Ye
- Department of Chemistry, College of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, PR China.
| | - Bao Hu
- Department of Chemistry, College of Chemical Engineering and Technology, Wuhan University of Science and Technology, Wuhan, Hubei 430081, PR China
| | - Faris El-Badri
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, United States
| | - Brandi M Hudson
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, United States
| | - Puay-Wah Phuan
- Department of Medicine, University of California, San Francisco, CA 94143-0521, United States; Department Physiology, University of California, San Francisco, CA 94143-0521, United States
| | - A S Verkman
- Department of Medicine, University of California, San Francisco, CA 94143-0521, United States; Department Physiology, University of California, San Francisco, CA 94143-0521, United States
| | - Dean J Tantillo
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, United States
| | - Mark J Kurth
- Department of Chemistry, University of California, One Shields Ave, Davis, CA 95616, United States.
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Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is unique among ion channels in that after its phosphorylation by protein kinase A (PKA), its ATP-dependent gating violates microscopic reversibility caused by the intimate involvement of ATP hydrolysis in controlling channel closure. Recent studies suggest a gating model featuring an energetic coupling between opening and closing of the gate in CFTR's transmembrane domains and association and dissociation of its two nucleotide-binding domains (NBDs). We found that permeant ions such as nitrate can increase the open probability (Po) of wild-type (WT) CFTR by increasing the opening rate and decreasing the closing rate. Nearly identical effects were seen with a construct in which activity does not require phosphorylation of the regulatory domain, indicating that nitrate primarily affects ATP-dependent gating steps rather than PKA-dependent phosphorylation. Surprisingly, the effects of nitrate on CFTR gating are remarkably similar to those of VX-770 (N-(2,4-Di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide), a potent CFTR potentiator used in clinics. These include effects on single-channel kinetics of WT CFTR, deceleration of the nonhydrolytic closing rate, and potentiation of the Po of the disease-associated mutant G551D. In addition, both VX-770 and nitrate increased the activity of a CFTR construct lacking NBD2 (ΔNBD2), indicating that these gating effects are independent of NBD dimerization. Nonetheless, whereas VX-770 is equally effective when applied from either side of the membrane, nitrate potentiates gating mainly from the cytoplasmic side, implicating a common mechanism for gating modulation mediated through two separate sites of action.
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Affiliation(s)
- Han-I Yeh
- Physician-Scientist Program, School of Medicine, National Yang-Ming University, Taipei, 112 Taiwan Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211
| | - Jiunn-Tyng Yeh
- Physician-Scientist Program, School of Medicine, National Yang-Ming University, Taipei, 112 Taiwan Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211 Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211
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Chen JH. A cocktail drug therapy for patients with cystic fibrosis? J Cyst Fibros 2014; 13:489-90. [PMID: 25088968 DOI: 10.1016/j.jcf.2014.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2014] [Indexed: 10/25/2022]
Affiliation(s)
- Jeng-Haur Chen
- Department of Physiology, HKU Shenzhen Institute of Research and Innovation, University of Hong Kong, Li Ka Shing Faculty of Medicine, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong, China.
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Coffman KC, Nguyen HH, Phuan PW, Hudson BM, Yu GJ, Bagdasarian AL, Montgomery D, Lodewyk MW, Yang B, Yoo CL, Verkman AS, Tantillo DJ, Kurth MJ. Constrained bithiazoles: small molecule correctors of defective ΔF508-CFTR protein trafficking. J Med Chem 2014; 57:6729-38. [PMID: 25061695 PMCID: PMC4136667 DOI: 10.1021/jm5007885] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Conformationally
constrained bithiazoles were previously found
to have improved efficacy over nonconstrained bithiazoles for correction
of defective cellular processing of the ΔF508 mutant cystic
fibrosis transmembrane conductance regulator (CFTR) protein. In this
study, two sets of constrained bithiazoles were designed, synthesized,
and tested in vitro using ΔF508–CFTR expressing epithelial
cells. The SAR data demonstrated that modulating the constraining
ring size between 7- versus 8-membered in these constrained bithiazole
correctors did not significantly enhance their potency (IC50), but strongly affected maximum efficacy (Vmax), with constrained bithiazoles 9e and 10c increasing Vmax by 1.5-fold
compared to benchmark bithiazole corr4a. The data suggest
that the 7- and 8-membered constrained ring bithiazoles are similar
in their ability to accommodate the requisite geometric constraints
during protein binding.
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Affiliation(s)
- Keith C Coffman
- Department of Chemistry, University of California , One Shields Avenue, Davis, California 95616, United States
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