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Olov N, Nour S, Harris AR, Li D, Cook M, Williams RJ, Cheeseman S, Nisbet DR. Using Nanoscale Passports To Understand and Unlock Ion Channels as Gatekeepers of the Cell. ACS NANO 2024; 18:22709-22733. [PMID: 39136685 DOI: 10.1021/acsnano.4c05654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Natural ion channels are proteins embedded in the cell membrane that control many aspects of cell and human physiology by acting as gatekeepers, regulating the flow of ions in and out of cells. Advances in nanotechnology have influenced the methods for studying ion channels in vitro, as well as ways to unlock the delivery of therapeutics by modulating them in vivo. This review provides an overview of nanotechnology-enabled approaches for ion channel research with a focus on the synthesis and applications of synthetic ion channels. Further, the uses of nanotechnology for therapeutic applications are critically analyzed. Finally, we provide an outlook on the opportunities and challenges at the intersection of nanotechnology and ion channels. This work highlights the key role of nanoscale interactions in the operation and modulation of ion channels, which may prompt insights into nanotechnology-enabled mechanisms to study and exploit these systems in the near future.
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Affiliation(s)
- Nafiseh Olov
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
| | - Shirin Nour
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Polymer Science Group, Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Alexander R Harris
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
| | - Dan Li
- Department of Chemical Engineering, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Mark Cook
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Department of Medicine, St Vincent's Hospital, Melbourne, Fitzroy, VIC 3065, Australia
| | - Richard J Williams
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Centre for Sustainable Bioproducts, Deakin University, Waurn Ponds, VIC 3217, Australia
- IMPACT, School of Medicine, Deakin University, Waurn Ponds, VIC 3217, Australia
| | - Samuel Cheeseman
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
| | - David R Nisbet
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
- Medical School, Faculty of Medicine, Dentistry and Health Science, The University of Melbourne, Parkville, VIC 3010, Melbourne, Australia
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Zhang J, Liu X, Zeng L, Hu Y. GABRP inhibits the progression of oesophageal cancer by regulating CFTR: Integrating bioinformatics analysis and experimental validation. Int J Exp Pathol 2024; 105:118-132. [PMID: 38989629 PMCID: PMC11263814 DOI: 10.1111/iep.12513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 05/23/2024] [Accepted: 06/08/2024] [Indexed: 07/12/2024] Open
Abstract
Oesophageal cancer (EC) is a malignancy which accounts for a substantial number of cancer-related deaths worldwide. The molecular mechanisms underlying the pathogenesis of EC have not been fully elucidated. GSE17351 and GSE20347 data sets from the Gene Expression Omnibus (GEO) database were employed to screen differentially expressed genes (DEGs). Reverse transcription quantitative PCR (RT-qPCR) was used to examine hub gene expression. ECA-109 and TE-12 cells were transfected using the pcDNA3.1 expression vector encoding GABRP. The cell counting kit-8 (CCK-8), cell scratch and Transwell assays were performed to assess the effect of GABRP on EC cell proliferation, migration and invasion. Epithelial-mesenchymal transition (EMT)-associated protein levels were measured by Western blotting. Subsequently, CFTR was knocked down to verify whether GABRP affected biological events in EC cells by targeting CFTR. Seven hub genes were identified, including GABRP, FLG, ENAH, KLF4, CD24, ABLIM3 and ABLIM1, which all could be used as diagnostic biomarkers for EC. The RT-qPCR results indicated that the expression levels of GABRP, FLG, KLF4, CD24, ABLIM3 and ABLIM1 were downregulated, whereas the expression level of ENAH was upregulated. In vitro functional assays demonstrated that GABRP overexpression suppressed the proliferation, migration, invasion and EMT of EC cells. Mechanistically, GABRP promoted the expression of CFTR, and CFTR knockdown significantly counteracted the influence of GABRP overexpression on biological events in EC cells. Overexpression of GABRP inhibited EC progression by increasing CFTR expression, which might be a new target for EC treatment.
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Affiliation(s)
- Jingzhi Zhang
- Department of GastroenterologyThe Affiliated Ganzhou Hospital of Nanchang UniversityGanzhou CityChina
| | - Xue Liu
- Department of GastroenterologyThe Affiliated Ganzhou Hospital of Nanchang UniversityGanzhou CityChina
| | - Ling Zeng
- Department of GastroenterologyThe Affiliated Ganzhou Hospital of Nanchang UniversityGanzhou CityChina
| | - Ying Hu
- Department of GastroenterologyThe First Affiliated Hospital of Gannan Medical UniversityGanzhou CityChina
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Upadhyay K, Nigam N, Gupta S, Tripathi SK, Jain A, Puri B. Current and future therapeutic approaches of CFTR and airway dysbiosis in an era of personalized medicine. J Family Med Prim Care 2024; 13:2200-2208. [PMID: 39027867 PMCID: PMC11254065 DOI: 10.4103/jfmpc.jfmpc_1085_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 12/06/2023] [Accepted: 01/17/2024] [Indexed: 07/20/2024] Open
Abstract
Cystic fibrosis (CF) is a life-threatening genetic disorder caused by mutations in the CFTR gene. This leads to a defective protein that impairs chloride transport, resulting in thick mucus buildup and chronic inflammation in the airways. The review discusses current and future therapeutic approaches for CFTR dysfunction and airway dysbiosis in the era of personalized medicine. Personalized medicine has revolutionized CF treatment with the advent of CFTR modulator therapies that target specific genetic mutations. These therapies have significantly improved patient outcomes, slowing disease progression, and enhancing quality of life. It also highlights the growing recognition of the airway microbiome's role in CF pathogenesis and discusses strategies to modulate the microbiome to further improve patient outcomes. This review discusses various therapeutic approaches for cystic fibrosis (CFTR) mutations, including adenovirus gene treatments, nonviral vectors, CRISPR/cas9 methods, RNA replacement, antisense-oligonucleotide-mediated DNA-based therapies, and cell-based therapies. It also introduces airway dysbiosis with CF and how microbes influence the lungs. The review highlights the importance of understanding the cellular and molecular causes of CF and the development of personalized medicine to improve quality of life and health outcomes.
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Affiliation(s)
- Kirti Upadhyay
- Cytogenetics Lab, Centre for Advance Research, King George’s Medical University, Lucknow, Uttar Pradesh, India
| | - Nitu Nigam
- Cytogenetics Lab, Centre for Advance Research, King George’s Medical University, Lucknow, Uttar Pradesh, India
| | - Surbhi Gupta
- Cytogenetics Lab, Centre for Advance Research, King George’s Medical University, Lucknow, Uttar Pradesh, India
| | - Surya Kant Tripathi
- Department of Respiratory Medicine, King George’s Medical University, Lucknow, Uttar Pradesh, India
| | - Amita Jain
- Department of Microbiology, King George’s Medical University, Lucknow, Uttar Pradesh, India
| | - Bipin Puri
- King George’s Medical University, Lucknow, Uttar Pradesh, India
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Brusa I, Sondo E, Pesce E, Tomati V, Gioia D, Falchi F, Balboni B, Ortega Martínez JA, Veronesi M, Romeo E, Margaroli N, Recanatini M, Girotto S, Pedemonte N, Roberti M, Cavalli A. Innovative Strategy toward Mutant CFTR Rescue in Cystic Fibrosis: Design and Synthesis of Thiadiazole Inhibitors of the E3 Ligase RNF5. J Med Chem 2023. [PMID: 37440686 PMCID: PMC10388311 DOI: 10.1021/acs.jmedchem.3c00608] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2023]
Abstract
In cystic fibrosis (CF), deletion of phenylalanine 508 (F508del) in the CF transmembrane conductance regulator (CFTR) is associated to misfolding and defective gating of the mutant channel. One of the most promising CF drug targets is the ubiquitin ligase RNF5, which promotes F508del-CFTR degradation. Recently, the first ever reported inhibitor of RNF5 was discovered, i.e., the 1,2,4-thiadiazol-5-ylidene inh-2. Here, we designed and synthesized a series of new analogues to explore the structure-activity relationships (SAR) of this class of compounds. SAR efforts ultimately led to compound 16, which showed a greater F508del-CFTR corrector activity than inh-2, good tolerability, and no toxic side effects. Analogue 16 increased the basal level of autophagy similar to what has been described with RNF5 silencing. Furthermore, co-treatment with 16 significantly improved the F508del-CFTR rescue induced by the triple combination elexacaftor/tezacaftor/ivacaftor in CFBE41o- cells. These findings validate the 1,2,4-thiadiazolylidene scaffold for the discovery of novel RNF5 inhibitors and provide evidence to pursue this unprecedented strategy for the treatment of CF.
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Affiliation(s)
- Irene Brusa
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Elvira Sondo
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | - Emanuela Pesce
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | - Valeria Tomati
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | - Dario Gioia
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Federico Falchi
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Beatrice Balboni
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | | | - Marina Veronesi
- Structural Biophysics and Translational Pharmacology Facility, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Elisa Romeo
- Structural Biophysics and Translational Pharmacology Facility, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Natasha Margaroli
- Structural Biophysics and Translational Pharmacology Facility, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Maurizio Recanatini
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Stefania Girotto
- Structural Biophysics and Translational Pharmacology Facility, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | | | - Marinella Roberti
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Andrea Cavalli
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
- Centre Européen de Calcul Atomique et Moléculaire, EPFL CECAM, 1015 Lousanne, Switzerland
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Effect of lentivirus-mediated CFTR overexpression on oxidative stress injury and inflammatory response in the lung tissue of COPD mouse model. Biosci Rep 2020; 40:221741. [PMID: 31894837 PMCID: PMC6992926 DOI: 10.1042/bsr20193667] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/13/2019] [Accepted: 12/19/2019] [Indexed: 12/15/2022] Open
Abstract
We aimed to investigate the regulatory mechanism of lentivirus-mediated overexpression of cystic fibrosis transmembrane conductance regulator (CFTR) in oxidative stress injury and inflammatory response in the lung tissue of mouse model of chronic obstructive pulmonary disease (COPD). COPD mouse model induced by cigarette smoke was established and normal mice were used as control. The mice were assigned into a normal group (control), a model group (untreated), an oe-CFTR group (injection of lentivirus overexpressing CFTR), and an oe-NC group (negative control, injection of lentivirus expressing irrelevant sequences). Compared with the oe-NC group, the oe-CFTR group had higher CFTR expression and a better recovery of pulmonary function. CFTR overexpression could inhibit the pulmonary endothelial cell apoptosis, reduce the levels of glutathione (GSH), reactive oxygen species (ROS), and malondialdehyde (MDA) and increase the values of superoxide dismutase (SOD), GSH peroxidase (GSH-Px), and total antioxidant capacity (T-AOC). The overexpression also led to reductions in the white blood cell (WBC) count in alveolus pulmonis, the concentrations of C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor-α, and the protein expressions of NF-κB p65, ERK, JNK, p-EPK, and p-JNK related to MAPK/NF-κB p65 signaling pathway. In conclusion, CFTR overexpression can protect lung tissues from injuries caused by oxidative stress and inflammatory response in COPD mouse model. The mechanism behind this may be related to the suppression of MAPK/NF-κB p65 signaling pathway.
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Gopallawa I, Lee RJ. Targeting the phosphoinositide-3-kinase/protein kinase B pathway in airway innate immunity. World J Biol Chem 2020; 11:30-51. [PMID: 33024516 PMCID: PMC7520643 DOI: 10.4331/wjbc.v11.i2.30] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/24/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023] Open
Abstract
The airway innate immune system maintains the first line of defense against respiratory infections. The airway epithelium and associated immune cells protect the respiratory system from inhaled foreign organisms. These cells sense pathogens via activation of receptors like toll-like receptors and taste family 2 receptors (T2Rs) and respond by producing antimicrobials, inflammatory cytokines, and chemokines. Coordinated regulation of fluid secretion and ciliary beating facilitates clearance of pathogens via mucociliary transport. Airway cells also secrete antimicrobial peptides and radicals to directly kill microorganisms and inactivate viruses. The phosphoinositide-3-kinase/protein kinase B (Akt) kinase pathway regulates multiple cellular targets that modulate cell survival and proliferation. Akt also regulates proteins involved in innate immune pathways. Akt phosphorylates endothelial nitric oxide synthase (eNOS) enzymes expressed in airway epithelial cells. Activation of eNOS can have anti-inflammatory, anti-bacterial, and anti-viral roles. Moreover, Akt can increase the activity of the transcription factor nuclear factor erythroid 2 related factor-2 that protects cells from oxidative stress and may limit inflammation. In this review, we summarize the recent findings of non-cancerous functions of Akt signaling in airway innate host defense mechanisms, including an overview of several known downstream targets of Akt involved in innate immunity.
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Affiliation(s)
- Indiwari Gopallawa
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Robert J Lee
- Department of Otorhinolaryngology and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
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Physiological Significance of Ion Transporters and Channels in the Stomach and Pathophysiological Relevance in Gastric Cancer. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:2869138. [PMID: 32104192 PMCID: PMC7040404 DOI: 10.1155/2020/2869138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/17/2019] [Accepted: 01/08/2020] [Indexed: 12/26/2022]
Abstract
Gastric cancer (GC) is a highly invasive and fatal malignant disease that accounts for 5.7% of new global cancer cases and is the third leading cause of cancer-related death. Acid/base homeostasis is critical for organisms because protein and enzyme function, cellular structure, and plasma membrane permeability change with pH. Various ion transporters are expressed in normal gastric mucosal epithelial cells and regulate gastric acid secretion, ion transport, and fluid absorption, thereby stabilizing the differentiation and homeostasis of gastric mucosal epithelial cells. Ion transporter dysfunction results in disordered ion transport, mucosa barrier dysfunction, and acid/base disturbances, causing gastric acid-related diseases such as chronic atrophic gastritis (CAG) and GC. This review summarizes the physiological functions of multiple ion transporters and channels in the stomach, including Cl− channels, Cl−/HCO3− exchangers, sodium/hydrogen exchangers (NHEs), and potassium (K+) channels, and their pathophysiological relevance in GC.
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Farkas B, Tordai H, Padányi R, Tordai A, Gera J, Paragi G, Hegedűs T. Discovering the chloride pathway in the CFTR channel. Cell Mol Life Sci 2020; 77:765-778. [PMID: 31327045 PMCID: PMC7039865 DOI: 10.1007/s00018-019-03211-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 06/22/2019] [Accepted: 06/26/2019] [Indexed: 12/15/2022]
Abstract
Cystic fibrosis (CF), a lethal monogenic disease, is caused by pathogenic variants of the CFTR chloride channel. The majority of CF mutations affect protein folding and stability leading overall to diminished apical anion conductance of epithelial cells. The recently published cryo-EM structures of full-length human and zebrafish CFTR provide a good model to gain insight into structure-function relationships of CFTR variants. Although, some of the structures were determined in the phosphorylated and ATP-bound active state, none of the static structures showed an open pathway for chloride permeation. Therefore, we performed molecular dynamics simulations to generate a conformational ensemble of the protein and used channel detecting algorithms to identify conformations with an opened channel. Our simulations indicate a main intracellular entry at TM4/6, a secondary pore at TM10/12, and a bottleneck region involving numerous amino acids from TM1, TM6, and TM12 in accordance with experiments. Since chloride ions entered the pathway in our equilibrium simulations, but did not traverse the bottleneck region, we performed metadynamics simulations, which revealed two possible exits. One of the chloride ions exits includes hydrophobic lipid tails that may explain the lipid-dependency of CFTR function. In summary, our in silico study provides a detailed description of a potential chloride channel pathway based on a recent cryo-EM structure and may help to understand the gating of the CFTR chloride channel, thus contributing to novel strategies to rescue dysfunctional mutants.
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Affiliation(s)
- Bianka Farkas
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Hedvig Tordai
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Rita Padányi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Attila Tordai
- Department of Pathophysiology, Semmelweis University, Budapest, Hungary
| | - János Gera
- Department of Medical Chemistry, University of Szeged, Szeged, Hungary
| | - Gábor Paragi
- MTA-SZTE Biomimetic System Research Group, Hungarian Academy of Sciences, Szeged, Hungary
- Institute of Physics, University of Pécs, Pecs, Hungary
| | - Tamás Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.
- MTA-SE Molecular Biophysics Research Group, Hungarian Academy of Sciences, Budapest, Hungary.
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Loukou I, Moustaki M, Plyta M, Douros K. Longitudinal changes in lung function following initiation of lumacaftor/ivacaftor combination. J Cyst Fibros 2019; 19:534-539. [PMID: 31676345 DOI: 10.1016/j.jcf.2019.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/14/2019] [Accepted: 09/16/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND The combination of lumacaftor and ivacaftor (LUM/IVA) is a recently approved CFTR modulator treatment for homozygous F508del CF patients. Our study aimed at evaluating the change in the rate of lung function decline after one-year treatment with LUM/IVA. METHODS The study evaluated patients homozygous for F508del, 12 to 23 years old. All had been treated for one year with LUM/IVA. The collected data included the percent predicted values of FEV1 (ppFEV1) and FVC (ppFVC), and the FEV1/FVC ratio (FEV1/FVC), that corresponded to 12, 24, and 36 months prior to, and 12 months after the initiation of LUM/IVA; also, the 3 highest values of the ppFEV1 (and the corresponding ppFVC, and FEV1/FVC) for the periods 0-12 months, 12-24 months, and 24-36 months prior to as well as the 12-month period after the initiation of LUM/IVA. The baseline lung function was estimated before the commencement of the drug. Data were analyzed longitudinally with generalized estimating equations models and continuous linear splines. A single knot was used that corresponded to the time point of LUM/IVA initiation. RESULTS Fifty-two patients were analyzed. The multivariate longitudinal analysis of spirometric indices with linear splines demonstrated a significant change in the slopes of ppFEV1 and ppFVC decline, reflecting a significant improvement after the initiation of LUM/IVA treatment. CONCLUSIONS In this real-world study, lung function improved over a relatively short time period of only one year, after the commencement of LUM/IVA.
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Affiliation(s)
- Ioanna Loukou
- Cystic Fibrosis Department, "Agia Sofia" Children's Hospital, Athens, Greece.
| | - Maria Moustaki
- Cystic Fibrosis Department, "Agia Sofia" Children's Hospital, Athens, Greece
| | - Marina Plyta
- Cystic Fibrosis Department, "Agia Sofia" Children's Hospital, Athens, Greece
| | - Konstantinos Douros
- Pediatric Allergy and Respiratory Unit, 3rd Department of Pediatrics, "Attikon" University Hospital, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece
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Ma Z, Yuan D, Cheng X, Tuo B, Liu X, Li T. Function of ion transporters in maintaining acid-base homeostasis of the mammary gland and the pathophysiological role in breast cancer. Am J Physiol Regul Integr Comp Physiol 2019; 318:R98-R111. [PMID: 31553634 DOI: 10.1152/ajpregu.00202.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The incidence of breast cancer is increasing year by year, and the pathogenesis is still unclear. Studies have shown that the high metabolism of solid tumors leads to an increase in hypoxia, glycolysis, production of lactic acid and carbonic acid, and extracellular acidification; a harsh microenvironment; and ultimately to tumor cell death. Approximately 50% of locally advanced breast cancers exhibit hypoxia and/or local hypoxia, and acid-base regulatory proteins play an important role in regulating milk secretion and maintaining mammary gland physiological function. Therefore, ion transporters have gradually become a hot topic in mammary gland and breast cancer research. This review focuses on the research progress of ion transporters in mammary glands and breast cancer. We hope to provide new targets for the treatment and prognosis of breast cancer.
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Affiliation(s)
- Zhiyuan Ma
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Dumin Yuan
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Xiaoming Cheng
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Taolang Li
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
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11
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Corradi V, Gu RX, Vergani P, Tieleman DP. Structure of Transmembrane Helix 8 and Possible Membrane Defects in CFTR. Biophys J 2019; 114:1751-1754. [PMID: 29694855 PMCID: PMC5936993 DOI: 10.1016/j.bpj.2018.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/30/2018] [Accepted: 03/05/2018] [Indexed: 12/31/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is an ion channel that regulates the flow of anions across epithelia. Mutations in CFTR cause cystic fibrosis. CFTR belongs to the ATP-binding cassette transporter superfamily, and gating is controlled by phosphorylation and ATP binding and hydrolysis. Recently obtained ATP-free and ATP-bound structures of zebrafish CFTR revealed an unwound segment of transmembrane helix (TM) 8, which appears to be a unique feature of CFTR not present in other ATP-binding cassette transporter structures. Here, using μs-long molecular dynamics simulations, we investigate the interactions formed by this TM8 segment with nearby helices in both ATP-free and ATP-bound states. We highlight ATP-dependent interactions as well as the structural role of TM8 in maintaining the functional architecture of the pore via interactions common to both the ATP-bound and ATP-free state. The results of the molecular dynamics simulations are discussed in the context of the gating mechanism of CFTR.
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Affiliation(s)
- Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Paola Vergani
- Research Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
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12
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Pranke I, Golec A, Hinzpeter A, Edelman A, Sermet-Gaudelus I. Emerging Therapeutic Approaches for Cystic Fibrosis. From Gene Editing to Personalized Medicine. Front Pharmacol 2019; 10:121. [PMID: 30873022 PMCID: PMC6400831 DOI: 10.3389/fphar.2019.00121] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 01/31/2019] [Indexed: 12/13/2022] Open
Abstract
An improved understanding of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) protein structure and the consequences of CFTR gene mutations have allowed the development of novel therapies targeting specific defects underlying CF. Some strategies are mutation specific and have already reached clinical development; some strategies include a read-through of the specific premature termination codons (read-through therapies, nonsense mediated decay pathway inhibitors for Class I mutations); correction of CFTR folding and trafficking to the apical plasma membrane (correctors for Class II mutations); and an increase in the function of CFTR channel (potentiators therapy for Class III mutations and any mutant with a residual function located at the membrane). Other therapies that are in preclinical development are not mutation specific and include gene therapy to edit the genome and stem cell therapy to repair the airway tissue. These strategies that are directed at the basic CF defects are now revolutionizing the treatment for patients and should positively impact their survival rates.
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Affiliation(s)
- Iwona Pranke
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Anita Golec
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Alexandre Hinzpeter
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Aleksander Edelman
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France
| | - Isabelle Sermet-Gaudelus
- INSERM U 1151, Institut Necker Enfants Malades, Université Paris Descartes, Paris, France.,Centre de Référence Maladie Rare, Mucoviscidose et Maladies de CFTR, Paris, France.,Faculté de Médecine, Université Paris Descartes, Paris, France
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13
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Hoffmann B, Elbahnsi A, Lehn P, Décout JL, Pietrucci F, Mornon JP, Callebaut I. Combining theoretical and experimental data to decipher CFTR 3D structures and functions. Cell Mol Life Sci 2018; 75:3829-3855. [PMID: 29779042 PMCID: PMC11105360 DOI: 10.1007/s00018-018-2835-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 05/04/2018] [Accepted: 05/07/2018] [Indexed: 12/15/2022]
Abstract
Cryo-electron microscopy (cryo-EM) has recently provided invaluable experimental data about the full-length cystic fibrosis transmembrane conductance regulator (CFTR) 3D structure. However, this experimental information deals with inactive states of the channel, either in an apo, quiescent conformation, in which nucleotide-binding domains (NBDs) are widely separated or in an ATP-bound, yet closed conformation. Here, we show that 3D structure models of the open and closed forms of the channel, now further supported by metadynamics simulations and by comparison with the cryo-EM data, could be used to gain some insights into critical features of the conformational transition toward active CFTR forms. These critical elements lie within membrane-spanning domains but also within NBD1 and the N-terminal extension, in which conformational plasticity is predicted to occur to help the interaction with filamin, one of the CFTR cellular partners.
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Affiliation(s)
- Brice Hoffmann
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France
- Iktos, Paris, France
| | - Ahmad Elbahnsi
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France
| | - Pierre Lehn
- INSERM U1078, SFR ScInBioS, Université de Bretagne Occidentale, Brest, France
| | | | - Fabio Pietrucci
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France
| | - Jean-Paul Mornon
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France.
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France
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14
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Muimo R, Alothaid HM, Mehta A. NM23 proteins: innocent bystanders or local energy boosters for CFTR? J Transl Med 2018; 98:272-282. [PMID: 29251738 DOI: 10.1038/labinvest.2017.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/25/2017] [Accepted: 09/12/2017] [Indexed: 12/17/2022] Open
Abstract
NM23 proteins NDPK-A and -B bind to the cystic fibrosis (CF) protein CFTR in different ways from kinases such as PKA, CK2 and AMPK or linkers to cell calcium such as calmodulin and annexins. NDPK-A (not -B) interacts with CFTR through reciprocal AMPK binding/control, whereas NDPK-B (not -A) binds directly to CFTR. NDPK-B can activate G proteins without ligand-receptor coupling, so perhaps NDPK-B's binding influences energy supply local to a nucleotide-binding site (NBD1) needed for CFTR to function. Curiously, CFTR (ABC-C7) is a member of the ATP-binding cassette (ABC) protein family that does not obey 'clan rules'; CFTR channels anions and is not a pump, regulates disparate processes, is itself regulated by multiple means and is so pleiotropic that it acts as a hub that orchestrates calcium signaling through its consorts such as calmodulin/annexins. Furthermore, its multiple partners make CFTR dance to different tunes in different cellular and subcellular locations as it recycles from the plasma membrane to endosomes. CFTR function in airway apical membranes is inhibited by smoking which has been dubbed 'acquired CF'. CFTR alone among family members possesses a trap for other proteins that it unfurls as a 'fish-net' and which bears consensus phosphorylation sites for many protein kinases, with PKA being the most canonical. Recently, the site of CFTR's commonest mutation has been proposed as a knock-in mutant that alters allosteric control of kinase CK2 by log orders of activity towards calmodulin and other substrates after CFTR fragmentation. This link from CK2 to calmodulin that binds the R region invokes molecular paths that control lumen formation, which is incomplete in the tracheas of some CF-affected babies. Thus, we are poised to understand the many roles of NDPK-A and -B in CFTR function and, especially lumen formation, which is defective in the gut and lungs of many CF babies.
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Affiliation(s)
- Richmond Muimo
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, University of Sheffield, Sheffield, UK
| | - Hani Mm Alothaid
- Department of Infection, Immunity and Cardiovascular Disease, The Medical School, University of Sheffield, Sheffield, UK
| | - Anil Mehta
- Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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15
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Gao X, Hwang TC. Spatial positioning of CFTR's pore-lining residues affirms an asymmetrical contribution of transmembrane segments to the anion permeation pathway. J Gen Physiol 2017; 147:407-22. [PMID: 27114613 PMCID: PMC4845689 DOI: 10.1085/jgp.201511557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 03/28/2016] [Indexed: 12/22/2022] Open
Abstract
CFTR is a chloride channel and a member of the ABC transporter superfamily; however, its structure is unknown. By making a series of cysteine mutants, Gao and Hwang show that CFTR lacks the twofold pseudo-symmetry seen in the permeation pathway of bone fide ABC transporters. The structural composition of CFTR’s anion permeation pathway has been proposed to consist of a short narrow region, flanked by two wide inner and outer vestibules, based on systematic cysteine scanning studies using thiol-reactive probes of various sizes. Although these studies identified several of the transmembrane segments (TMs) as pore lining, the exact spatial relationship between pore-lining elements remains under debate. Here, we introduce cysteine pairs in several key pore-lining positions in TM1, 6, and 12 and use Cd2+ as a probe to gauge the spatial relationship of these residues within the pore. We find that inhibition of single cysteine CFTR mutants, such as 102C in TM1 or 341C in TM6, by intracellular Cd2+ is readily reversible upon removal of the metal ion. However, the inhibitory effect of Cd2+ on the double mutant 102C/341C requires the chelating agent dithiothreitol (DTT) for rapid reversal, indicating that 102C and 341C are close enough to the internal edge of the narrow region to coordinate one Cd2+ ion between them. We observe similar effects of extracellular Cd2+ on TM1/TM6 cysteine pairs 106C/337C, 107C/337C, and 107C/338C, corroborating the idea that these paired residues are physically close to each other at the external edge of the narrow region. Although these data paint a picture of relatively symmetrical contributions to CFTR’s pore by TM1 and TM6, introducing cysteine pairs between TM6 and TM12 (348C/1141C, 348C/1144C, and 348C/1145C) or between TM1 and TM12 (95C/1141C) yields results that contest the long-held principle of twofold pseudo-symmetry in the assembly of ABC transporters’ TMs. Collectively, these findings not only advance our current understanding of the architecture of CFTR’s pore, but could serve as a guide for refining computational models of CFTR by imposing physical constraints among pore-lining residues.
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Affiliation(s)
- Xiaolong Gao
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211 Department of Biological Engineering, University of Missouri, Columbia, MO 65211
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211 Department of Biological Engineering, University of Missouri, Columbia, MO 65211 Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211
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16
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Das J, Aleksandrov AA, Cui L, He L, Riordan JR, Dokholyan NV. Transmembrane helical interactions in the CFTR channel pore. PLoS Comput Biol 2017. [PMID: 28640808 PMCID: PMC5501672 DOI: 10.1371/journal.pcbi.1005594] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene affect CFTR protein biogenesis or its function as a chloride channel, resulting in dysregulation of epithelial fluid transport in the lung, pancreas and other organs in cystic fibrosis (CF). Development of pharmaceutical strategies to treat CF requires understanding of the mechanisms underlying channel function. However, incomplete 3D structural information on the unique ABC ion channel, CFTR, hinders elucidation of its functional mechanism and correction of cystic fibrosis causing mutants. Several CFTR homology models have been developed using bacterial ABC transporters as templates but these have low sequence similarity to CFTR and are not ion channels. Here, we refine an earlier model in an outward (OWF) and develop an inward (IWF) facing model employing an integrated experimental-molecular dynamics simulation (200 ns) approach. Our IWF structure agrees well with a recently solved cryo-EM structure of a CFTR IWF state. We utilize cysteine cross-linking to verify positions and orientations of residues within trans-membrane helices (TMHs) of the OWF conformation and to reconstruct a physiologically relevant pore structure. Comparison of pore profiles of the two conformations reveal a radius sufficient to permit passage of hydrated Cl- ions in the OWF but not the IWF model. To identify structural determinants that distinguish the two conformations and possible rearrangements of TMHs within them responsible for channel gating, we perform cross-linking by bifunctional reagents of multiple predicted pairs of cysteines in TMH 6 and 12 and 6 and 9. To determine whether the effects of cross-linking on gating observed are the result of switching of the channel from open to close state, we also treat the same residue pairs with monofunctional reagents in separate experiments. Both types of reagents prevent ion currents indicating that pore blockage is primarily responsible.
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Affiliation(s)
- Jhuma Das
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Andrei A. Aleksandrov
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Liying Cui
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Lihua He
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - John R. Riordan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail: (JRR); (NVD)
| | - Nikolay V. Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail: (JRR); (NVD)
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17
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Negoda A, El Hiani Y, Cowley EA, Linsdell P. Contribution of a leucine residue in the first transmembrane segment to the selectivity filter region in the CFTR chloride channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1049-1058. [DOI: 10.1016/j.bbamem.2017.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 02/01/2017] [Accepted: 02/20/2017] [Indexed: 12/15/2022]
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18
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Mondejar-Lopez P, Pastor-Vivero MD, Sanchez-Solis M, Escribano A. Cystic fibrosis treatment: targeting the basic defect. Expert Opin Orphan Drugs 2017. [DOI: 10.1080/21678707.2017.1280390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | | | - Manuel Sanchez-Solis
- Cystic Fibrosis Unit, Virgen de la Arrixaca University Hospital, Murcia, Spain
- IMIB Bio-Research Institute, Murcia, Spain
| | - Amparo Escribano
- Pediatric Pulmonology and Cystic Fibrosis Unit, Clinic University Hospital, Valencia, Spain
- University of Valencia, Valencia, Spain
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19
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Callebaut I, Hoffmann B, Lehn P, Mornon JP. Molecular modelling and molecular dynamics of CFTR. Cell Mol Life Sci 2017; 74:3-22. [PMID: 27717958 PMCID: PMC11107702 DOI: 10.1007/s00018-016-2385-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/11/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) protein is a member of the ATP-binding cassette (ABC) transporter superfamily that functions as an ATP-gated channel. Considerable progress has been made over the last years in the understanding of the molecular basis of the CFTR functions, as well as dysfunctions causing the common genetic disease cystic fibrosis (CF). This review provides a global overview of the theoretical studies that have been performed so far, especially molecular modelling and molecular dynamics (MD) simulations. A special emphasis is placed on the CFTR-specific evolution of an ABC transporter framework towards a channel function, as well as on the understanding of the effects of disease-causing mutations and their specific modulation. This in silico work should help structure-based drug discovery and design, with a view to develop CFTR-specific pharmacotherapeutic approaches for the treatment of CF in the context of precision medicine.
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Affiliation(s)
- Isabelle Callebaut
- UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, IUC, Case 115, IMPMC, Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005, Paris Cedex 05, France.
| | - Brice Hoffmann
- UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, IUC, Case 115, IMPMC, Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005, Paris Cedex 05, France
| | - Pierre Lehn
- INSERM U1078, SFR ScInBioS, Université de Bretagne Occidentale, Brest, France
| | - Jean-Paul Mornon
- UMR CNRS 7590, Museum National d'Histoire Naturelle, IRD UMR 206, IUC, Case 115, IMPMC, Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005, Paris Cedex 05, France
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20
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Linsdell P. Architecture and functional properties of the CFTR channel pore. Cell Mol Life Sci 2017; 74:67-83. [PMID: 27699452 PMCID: PMC11107662 DOI: 10.1007/s00018-016-2389-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/12/2022]
Abstract
The main function of the cystic fibrosis transmembrane conductance regulator (CFTR) is as an ion channel for the movement of small anions across epithelial cell membranes. As an ion channel, CFTR must form a continuous pathway across the cell membrane-referred to as the channel pore-for the rapid electrodiffusional movement of ions. This review summarizes our current understanding of the architecture of the channel pore, as defined by electrophysiological analysis and molecular modeling studies. This includes consideration of the characteristic functional properties of the pore, definition of the overall shape of the entire extent of the pore, and discussion of how the molecular structure of distinct regions of the pore might control different facets of pore function. Comparisons are drawn with closely related proteins that are not ion channels, and also with structurally unrelated proteins with anion channel function. A simple model of pore function is also described.
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Affiliation(s)
- Paul Linsdell
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS, B3H 4R2, Canada.
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21
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Ong T, Ramsey BW. New Therapeutic Approaches to Modulate and Correct Cystic Fibrosis Transmembrane Conductance Regulator. Pediatr Clin North Am 2016; 63:751-64. [PMID: 27469186 PMCID: PMC5478192 DOI: 10.1016/j.pcl.2016.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) modulators are clinically available personalized medicines approved for some individuals with cystic fibrosis (CF) to target the underlying defect of disease. This review summarizes strategies used to develop CFTR modulators as therapies that improve function and availability of CFTR protein. Lessons learned from dissemination of ivacaftor across the CF population responsive to this therapy and future approaches to predict and monitor treatment response of CFTR modulators are discussed. The goal remains to expand patient-centered and personalized therapy to all patients with CF, ultimately improving life expectancy and quality of life for this disease.
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Affiliation(s)
- Thida Ong
- University of Washington, Department of Pediatrics,Seattle Children’s Hospital, Division of Pulmonary and Sleep Medicine
| | - Bonnie W. Ramsey
- University of Washington, Department of Pediatrics,Seattle Children’s Research Institute, Center for Clinical and Translational Research,Corresponding Author: Bonnie Ramsey, MD, Seattle Children’s Research Institute, 2001 8th Avenue, Suite 400, M/S CW8-5B, Seattle, WA 98121, Tel: 206-987-5725, Fax: 206-987-7505,
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22
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El Hiani Y, Negoda A, Linsdell P. Cytoplasmic pathway followed by chloride ions to enter the CFTR channel pore. Cell Mol Life Sci 2016; 73:1917-25. [PMID: 26659082 PMCID: PMC11108287 DOI: 10.1007/s00018-015-2113-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 11/18/2015] [Accepted: 12/07/2015] [Indexed: 12/19/2022]
Abstract
Most ATP-binding cassette (ABC) proteins function as ATP-dependent membrane pumps. One exception is the cystic fibrosis transmembrane conductance regulator (CFTR), an ABC protein that functions as a Cl(-) ion channel. As such, the CFTR protein must form a continuous pathway for the movement of Cl(-) ions from the cytoplasm to the extracellular solution when in its open channel state. Extensive functional investigations have characterized most parts of this Cl(-) permeation pathway. However, one region remains unexplored-the pathway connecting the cytoplasm to the membrane-spanning pore. We used patch clamp recording and extensive substituted cysteine accessibility mutagenesis to identify amino acid side-chains in cytoplasmic regions of CFTR that lie close to the pathway taken by Cl(-) ions as they pass from the cytoplasm through this pathway. Our results suggest that Cl(-) ions enter the permeation pathway via a single lateral tunnel formed by the cytoplasmic parts of the protein, and then follow a fairly direct central pathway towards the membrane-spanning parts of the protein. However, this pathway is not lined continuously by any particular part of the protein; instead, the contributions of different cytoplasmic regions of the protein appear to change as the permeation pathway approaches the membrane, which appears to reflect the ways in which different cytoplasmic regions of the protein are oriented towards its central axis. Our results allow us to define for the first time the complete Cl(-) permeation pathway in CFTR, from the cytoplasm to the extracellular solution.
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Affiliation(s)
- Yassine El Hiani
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS, B3H 4R2, Canada
| | - Alexander Negoda
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS, B3H 4R2, Canada
| | - Paul Linsdell
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS, B3H 4R2, Canada.
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23
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Qian F, Liu L, Liu Z, Lu C. The pore architecture of the cystic fibrosis transmembrane conductance regulator channel revealed by co-mutation in pore-forming transmembrane regions. Physiol Res 2016; 65:505-15. [PMID: 27070741 DOI: 10.33549/physiolres.933143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel contains 12 transmembrane (TM) regions that are presumed to form the channel pore. However, there is no direct evidence clearly illustrating the involvement of these transmembrane regions in the actual CFTR pore structure. To obtain insight into the architecture of the CFTR channel pore, we used patch clamp recording techniques and a strategy of co-mutagenesis of two potential pore-forming transmembrane regions (TM1 and TM6) to investigate the collaboration of these two TM regions. We performed a range of specific functional assays comparing the single channel conductance, anion binding, and anion selectivity properties of the co-mutated CFTR variants, and the results indicated that TM1 and TM6 play vital roles in forming the channel pore and, thus, determine the functional properties of the channel. Furthermore, we provided functional evidence that the amino acid threonine (T338) in TM6 has synergic effects with lysine (K95) in TM1. Therefore, we propose that these two residues have functional collaboration in the CFTR channel pore and may collectively form a selective filter.
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Affiliation(s)
- F Qian
- Laboratory of Neuronal Network and Brain Diseases Modulation, Yangtze University, Jingzhou, Hubei province, China.
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24
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Linsdell P. Anion conductance selectivity mechanism of the CFTR chloride channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:740-7. [DOI: 10.1016/j.bbamem.2016.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/11/2016] [Accepted: 01/13/2016] [Indexed: 02/08/2023]
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25
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Structural Changes Fundamental to Gating of the Cystic Fibrosis Transmembrane Conductance Regulator Anion Channel Pore. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 925:13-32. [PMID: 27311317 DOI: 10.1007/5584_2016_33] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial cell anion channel. Potentiator drugs used in the treatment of cystic fibrosis act on the channel to increase overall channel function, by increasing the stability of its open state and/or decreasing the stability of its closed state. The structure of the channel in either the open state or the closed state is not currently known. However, changes in the conformation of the protein as it transitions between these two states have been studied using functional investigation and molecular modeling techniques. This review summarizes our current understanding of the architecture of the transmembrane channel pore that controls the movement of chloride and other small anions, both in the open state and in the closed state. Evidence for different kinds of changes in the conformation of the pore as it transitions between open and closed states is described, as well as the mechanisms by which these conformational changes might be controlled to regulate normal channel gating. The ways that key conformational changes might be targeted by small compounds to influence overall CFTR activity are also discussed. Understanding the changes in pore structure that might be manipulated by such small compounds is key to the development of novel therapeutic strategies for the treatment of cystic fibrosis.
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26
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Solomon GM, Marshall SG, Ramsey BW, Rowe SM. Breakthrough therapies: Cystic fibrosis (CF) potentiators and correctors. Pediatr Pulmonol 2015; 50 Suppl 40:S3-S13. [PMID: 26097168 PMCID: PMC4620567 DOI: 10.1002/ppul.23240] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 12/28/2022]
Abstract
Cystic Fibrosis is caused by mutations in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene resulting in abnormal protein function. Recent advances of targeted molecular therapies and high throughput screening have resulted in multiple drug therapies that target many important mutations in the CFTR protein. In this review, we provide the latest results and current progress of CFTR modulators for the treatment of cystic fibrosis, focusing on potentiators of CFTR channel gating and Phe508del processing correctors for the Phe508del CFTR mutation. Special emphasis is placed on the molecular basis underlying these new therapies and emerging results from the latest clinical trials. The future directions for augmenting the rescue of Phe508del with CFTR modulators are also emphasized.
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Affiliation(s)
- George M Solomon
- Department of Medicine and the Gregory Fleming James Cystic Fibrosis Research Center, Birmingham, Alabama
| | - Susan G Marshall
- Division of Pulmonary Medicine, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington
| | - Bonnie W Ramsey
- Division of Pulmonary Medicine, Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington.,Center for Clinical and Translational Research, Seattle Children's Research Institute, Seattle, Washington
| | - Steven M Rowe
- Department of Medicine and the Gregory Fleming James Cystic Fibrosis Research Center, Birmingham, Alabama.,Departments of Medicine, Pediatrics, Cell Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
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27
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Corradi V, Vergani P, Tieleman DP. Cystic Fibrosis Transmembrane Conductance Regulator (CFTR): CLOSED AND OPEN STATE CHANNEL MODELS. J Biol Chem 2015; 290:22891-906. [PMID: 26229102 PMCID: PMC4645605 DOI: 10.1074/jbc.m115.665125] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 01/06/2023] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a member of the ATP-binding cassette (ABC) transporter superfamily. CFTR controls the flow of anions through the apical membrane of epithelia. Dysfunctional CFTR causes the common lethal genetic disease cystic fibrosis. Transitions between open and closed states of CFTR are regulated by ATP binding and hydrolysis on the cytosolic nucleotide binding domains, which are coupled with the transmembrane (TM) domains forming the pathway for anion permeation. Lack of structural data hampers a global understanding of CFTR and thus the development of "rational" approaches directly targeting defective CFTR. In this work, we explored possible conformational states of the CFTR gating cycle by means of homology modeling. As templates, we used structures of homologous ABC transporters, namely TM(287-288), ABC-B10, McjD, and Sav1866. In the light of published experimental results, structural analysis of the transmembrane cavity suggests that the TM(287-288)-based CFTR model could correspond to a commonly occupied closed state, whereas the McjD-based model could represent an open state. The models capture the important role played by Phe-337 as a filter/gating residue and provide structural information on the conformational transition from closed to open channel.
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Affiliation(s)
- Valentina Corradi
- From the Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta T2N 1N4, Canada and
| | - Paola Vergani
- Research Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D Peter Tieleman
- From the Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, Alberta T2N 1N4, Canada and
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28
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Linsdell P. Interactions between permeant and blocking anions inside the CFTR chloride channel pore. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1573-90. [DOI: 10.1016/j.bbamem.2015.04.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/08/2015] [Accepted: 04/09/2015] [Indexed: 12/19/2022]
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29
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Khoufache K. The vectorial transport of salts and water is crucial for respiratory epithelial cell lines. Respir Res 2015; 16:70. [PMID: 26068044 PMCID: PMC4466861 DOI: 10.1186/s12931-015-0235-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 06/10/2015] [Indexed: 11/10/2022] Open
Abstract
Primary culture of respiratory epithelial cells is useful to study the pathophysiology of respiratory diseases. However, such primary culture has been very limited because of its high dependence on the availability of biopsies and the long time required to reach confluence. Therefore, cell lines are an alternative to primary cultures because they reach confluence faster and some can maintain their differentiation abilities. However, unlike primary cultures and native tissues just some cell lines are able to polarize, with normal channel functionality and transepithelial ionic flux.
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Affiliation(s)
- Khaled Khoufache
- Research Center, Saint-François d'Assise Hospital, Centre Hospitalier Universitaire de Québec (CHUQ), Québec City, QC, Canada.
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30
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El Hiani Y, Linsdell P. Functional Architecture of the Cytoplasmic Entrance to the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel Pore. J Biol Chem 2015; 290:15855-15865. [PMID: 25944907 DOI: 10.1074/jbc.m115.656181] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Indexed: 12/19/2022] Open
Abstract
As an ion channel, the cystic fibrosis transmembrane conductance regulator must form a continuous pathway for the movement of Cl(-) and other anions between the cytoplasm and the extracellular solution. Both the structure and the function of the membrane-spanning part of this pathway are well defined. In contrast, the structure of the pathway that connects the cytoplasm to the membrane-spanning regions is unknown, and functional roles for different parts of the protein forming this pathway have not been described. We used patch clamp recording and substituted cysteine accessibility mutagenesis to identify positively charged amino acid side chains that attract cytoplasmic Cl(-) ions to the inner mouth of the pore. Our results indicate that the side chains of Lys-190, Arg-248, Arg-303, Lys-370, Lys-1041, and Arg-1048, located in different intracellular loops of the protein, play important roles in the electrostatic attraction of Cl(-) ions. Mutation and covalent modification of these residues have charge-dependent effects on the rate of Cl(-) permeation, demonstrating their functional role in maximization of Cl(-) flux. Other nearby positively charged side chains were not involved in electrostatic interactions with Cl(-). The location of these Cl(-)-attractive residues suggests that cytoplasmic Cl(-) ions enter the pore via a lateral portal located between the cytoplasmic extensions to the fourth and sixth transmembrane helices; a secondary, functionally less relevant portal might exist between the extensions to the 10th and 12th transmembrane helices. These results define the cytoplasmic mouth of the pore and show how it attracts Cl(-) ions from the cytoplasm.
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Affiliation(s)
- Yassine El Hiani
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Paul Linsdell
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
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31
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Rubaiy HN, Linsdell P. Location of a permeant anion binding site in the cystic fibrosis transmembrane conductance regulator chloride channel pore. J Physiol Sci 2015; 65:233-41. [PMID: 25673337 PMCID: PMC10717427 DOI: 10.1007/s12576-015-0359-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 01/24/2015] [Indexed: 01/15/2023]
Abstract
In the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, lyotropic anions with high permeability also bind relatively tightly within the pore. However, the location of permeant anion binding sites, as well as their relationship to anion permeability, is not known. We have identified lysine residue K95 as a key determinant of permeant anion binding in the CFTR pore. Lyotropic anion binding affinity is related to the number of positively charged amino acids located in the inner vestibule of the pore. However, mutations that change the number of positive charges in this pore region have minimal effects on anion permeability. In contrast, a mutation at the narrow pore region alters permeability with minimal effects on anion binding. Our results suggest that a localized permeant anion binding site exists in the pore; however, anion binding to this site has little influence over anion permeability. Implications of this work for the mechanisms of anion recognition and permeability in CFTR are discussed.
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Affiliation(s)
- Hussein N. Rubaiy
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS B3H 4R2 Canada
| | - Paul Linsdell
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS B3H 4R2 Canada
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32
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Mornon JP, Hoffmann B, Jonic S, Lehn P, Callebaut I. Full-open and closed CFTR channels, with lateral tunnels from the cytoplasm and an alternative position of the F508 region, as revealed by molecular dynamics. Cell Mol Life Sci 2015; 72:1377-403. [PMID: 25287046 PMCID: PMC11113974 DOI: 10.1007/s00018-014-1749-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 09/28/2014] [Accepted: 09/29/2014] [Indexed: 12/17/2022]
Abstract
In absence of experimental 3D structures, several homology models, based on ABC exporter 3D structures, have provided significant insights into the molecular mechanisms underlying the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, a chloride channel whose defects are associated with cystic fibrosis (CF). Until now, these models, however, did not furnished much insights into the continuous way that ions could follow from the cytosol to the extracellular milieu in the open form of the channel. Here, we have built a refined model of CFTR, based on the outward-facing Sav1866 experimental 3D structure and integrating the evolutionary and structural information available today. Molecular dynamics simulations revealed significant conformational changes, resulting in a full-open channel, accessible from the cytosol through lateral tunnels displayed in the long intracellular loops (ICLs). At the same time, the region of nucleotide-binding domain 1 in contact with one of the ICLs and carrying amino acid F508, the deletion of which is the most common CF-causing mutation, was found to adopt an alternative but stable position. Then, in a second step, this first stable full-open conformation evolved toward another stable state, in which only a limited displacement of the upper part of the transmembrane helices leads to a closure of the channel, in a conformation very close to that adopted by the Atm1 ABC exporter, in an inward-facing conformation. These models, supported by experimental data, provide significant new insights into the CFTR structure-function relationships and into the possible impact of CF-causing mutations.
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Affiliation(s)
- Jean-Paul Mornon
- IMPMC, Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7590, Museum National d’Histoire Naturelle, IRD UMR 206, IUC, Case 115, 4 Place Jussieu, 75005 Paris Cedex 05, France
| | - Brice Hoffmann
- IMPMC, Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7590, Museum National d’Histoire Naturelle, IRD UMR 206, IUC, Case 115, 4 Place Jussieu, 75005 Paris Cedex 05, France
| | - Slavica Jonic
- IMPMC, Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7590, Museum National d’Histoire Naturelle, IRD UMR 206, IUC, Case 115, 4 Place Jussieu, 75005 Paris Cedex 05, France
| | - Pierre Lehn
- INSERM U1078, SFR ScInBioS, Université de Bretagne Occidentale, Brest, France
| | - Isabelle Callebaut
- IMPMC, Sorbonne Universités, UPMC Univ Paris 06, UMR CNRS 7590, Museum National d’Histoire Naturelle, IRD UMR 206, IUC, Case 115, 4 Place Jussieu, 75005 Paris Cedex 05, France
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33
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Abstract
Thyroid follicular epithelial cells produce thyroxine (T4) and its physiologically active derivative, 3,3',5-triiodothyronine (T3), hormones that regulate critical developmental and metabolic functions. In order for the thyroid to form hormone precursor, iodide, the defining element in thyroid hormone, must cross both blood-facing and luminal sides of the follicular epithelium. The pathway for uptake from blood is well understood, but the mechanism(s) that enable iodide to cross the luminally facing apical membrane remain obscure. This chapter considers the physiological properties of several molecularly characterized anion transport proteins, all of which potentially contribute to the overall mechanism of apical iodide efflux.
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Affiliation(s)
- Peying Fong
- Department of Anatomy and Physiology, Kansas State University College of Veterinary Medicine, Manhattan, Kansas, USA.
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34
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Abstract
Experimental and computational studies have painted a picture of the chloride permeation pathway in cystic fibrosis transmembrane conductance regulator (CFTR) as a short narrow tunnel flanked by wider inner and outer vestibules. Although these studies also identified a number of transmembrane segments (TMs) as pore-lining, the exact location of CFTR's gate(s) remains unknown. Here, using a channel-permeant probe, [Au(CN)2](-), we provide evidence that CFTR bears a gate that coincides with the predicted narrow section of the pore defined as residues 338-341 in TM6. Specifically, cysteines introduced cytoplasmic to the narrow region (i.e., positions 344 in TM6 and 1148 in TM12) can be modified by intracellular [Au(CN)2](-) in both open and closed states, corroborating the conclusion that the internal vestibule does not harbor a gate. However, cysteines engineered to positions external to the presumed narrow region (e.g., 334, 335, and 337 in TM6) are all nonreactive toward cytoplasmic [Au(CN)2](-) in the absence of ATP, whereas they can be better accessed by extracellular [Au(CN)2](-) when the open probability is markedly reduced by introducing a second mutation, G1349D. As [Au(CN)2](-) and chloride ions share the same permeation pathway, these results imply a gate is situated between amino acid residues 337 and 344 along TM6, encompassing the very segment that may also serve as the selectivity filter for CFTR. The unique position of a gate in the middle of the ion translocation pathway diverges from those seen in ATP-binding cassette (ABC) transporters and thus distinguishes CFTR from other members of the ABC transporter family.
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35
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Qian F, Li T, Yang F, Liu L. Stoichiometry and novel gating mechanism within the cystic fibrosis transmembrane conductance regulator channel. Exp Physiol 2014; 99:1611-23. [DOI: 10.1113/expphysiol.2014.081034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Feng Qian
- Department of Medical Function; School of Medicine; Yangtze University; Jingzhou Hubei Province 434023 China
| | - Tao Li
- Department of Biology; College of Chemistry and Life Sciences; Zhejiang Normal University; Jinhua Zhejiang Province 321004 China
| | - Fei Yang
- Department of Medical Function; School of Medicine; Yangtze University; Jingzhou Hubei Province 434023 China
| | - Lian Liu
- Department of Medical Function; School of Medicine; Yangtze University; Jingzhou Hubei Province 434023 China
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36
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El Hiani Y, Linsdell P. Conformational changes opening and closing the CFTR chloride channel: insights from cysteine scanning mutagenesis. Biochem Cell Biol 2014; 92:481-8. [PMID: 25367045 DOI: 10.1139/bcb-2014-0038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cystic fibrosis, the most common lethal genetic disease affecting young people in North America, is caused by failure of the chloride ion channel known as CFTR (cystic fibrosis transmembrane conductance regulator). CFTR belongs to the large family of ATP-binding cassette (ABC) membrane transporters. In CFTR, ATP-driven events at the nucleotide-binding domains (NBDs) open and close a gate that controls chloride permeation. However, the conformational changes concomitant with opening and closing of the CFTR gate are unknown. Diverse techniques including substituted cysteine accessibility method, disulfide cross-linking, and patch-clamp recording have been used to explore CFTR channel structure. Here, we consider the architecture of both the open and the closed CFTR channel. We review how CFTR channel structure changes between the closed and the open channel conformations and portray the relative function of both cytoplasmic and vestigial gates during the gating cycle. Understanding how the CFTR channel gates chloride permeation is central for understanding how CFTR defects lead to CF. Such knowledge opens the door for novel ways to maximize CFTR channel activity in a CF setting.
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Affiliation(s)
- Yassine El Hiani
- Department of Physiology & Biophysics, Dalhousie University, Halifax, NS B3H 4R2, Canada
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37
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El Hiani Y, Linsdell P. Metal bridges illuminate transmembrane domain movements during gating of the cystic fibrosis transmembrane conductance regulator chloride channel. J Biol Chem 2014; 289:28149-59. [PMID: 25143385 DOI: 10.1074/jbc.m114.593103] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Opening and closing of the cystic fibrosis transmembrane conductance regulator are controlled by ATP binding and hydrolysis by the cytoplasmic nucleotide-binding domains. Different conformational changes in the channel pore have been described during channel opening and closing; however, the relative importance of these changes to the process of gating the pore is not known. We have used patch clamp recording to identify high affinity Cd(2+) bridges formed between pairs of pore-lining cysteine residues introduced into different transmembrane α-helices (TMs). Seven Cd(2+) bridges were identified forming between cysteines in TMs 6 and 12. Interestingly, each of these Cd(2+) bridges apparently formed only in closed channels, and their formation stabilized the closed state. In contrast, a single Cd(2+) bridge identified between cysteines in TMs 1 and 12 stabilized the channel open state. Analysis of the pattern of Cd(2+) bridge formation in different channel states suggests that lateral separation and convergence of different TMs, rather than relative rotation or translation of different TMs, is the key conformational change that causes the channel pore to open and close.
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Affiliation(s)
- Yassine El Hiani
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Paul Linsdell
- From the Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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38
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Broadbent SD, Wang W, Linsdell P. Interaction between 2 extracellular loops influences the activity of the cystic fibrosis transmembrane conductance regulator chloride channel. Biochem Cell Biol 2014; 92:390-6. [PMID: 25253636 DOI: 10.1139/bcb-2014-0066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Activity of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is thought to be controlled by cytoplasmic factors. However, recent evidence has shown that overall channel activity is also influenced by extracellular anions that interact directly with the extracellular loops (ECLs) of the CFTR protein. Very little is known about the structure of the ECLs or how substances interacting with these ECLs might affect CFTR function. We used patch-clamp recording to investigate the accessibility of cysteine-reactive reagents to cysteines introduced throughout ECL1 and 2 key sites in ECL4. Furthermore, interactions between ECL1 and ECL4 were investigated by the formation of disulfide crosslinks between cysteines introduced into these 2 regions. Crosslinks could be formed between R899C (in ECL4) and a number of sites in ECL1 in a manner that was dependent on channel activity, suggesting that the relative orientation of these 2 loops changes on activation. Formation of these crosslinks inhibited channel function, suggesting that relative movement of these ECLs is important to normal channel function. Implications of these findings for the effects of mutations in the ECLs that are associated with cystic fibrosis and interactions with extracellular substances that influence channel activity are discussed.
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Affiliation(s)
- Steven D Broadbent
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS B3H 4R2, Canada
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39
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Wang Y, Wrennall JA, Cai Z, Li H, Sheppard DN. Understanding how cystic fibrosis mutations disrupt CFTR function: from single molecules to animal models. Int J Biochem Cell Biol 2014; 52:47-57. [PMID: 24727426 DOI: 10.1016/j.biocel.2014.04.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 12/21/2022]
Abstract
Defective epithelial ion transport is the hallmark of the life-limiting genetic disease cystic fibrosis (CF). This abnormality is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), the ATP-binding cassette transporter that functions as a ligand-gated anion channel. Since the identification of the CFTR gene, almost 2000 disease-causing mutations associated with a spectrum of clinical phenotypes have been reported, but the majority remain poorly characterised. Studies of a small number of mutations including the most common, F508del-CFTR, have identified six general mechanisms of CFTR dysfunction. Here, we review selectively progress to understand how CF mutations disrupt CFTR processing, stability and function. We explore CFTR structure and function to explain the molecular mechanisms of CFTR dysfunction and highlight new knowledge of disease pathophysiology emerging from large animal models of CF. Understanding CFTR dysfunction is crucial to the development of transformational therapies for CF patients.
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Affiliation(s)
- Yiting Wang
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Joe A Wrennall
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Zhiwei Cai
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Hongyu Li
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - David N Sheppard
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, UK.
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40
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State-dependent blocker interactions with the CFTR chloride channel: implications for gating the pore. Pflugers Arch 2014; 466:2243-55. [DOI: 10.1007/s00424-014-1501-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 03/10/2014] [Accepted: 03/11/2014] [Indexed: 02/06/2023]
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