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Radomsky T, Anderson RC, Millar RP, Newton CL. Restoring function to inactivating G protein-coupled receptor variants in the hypothalamic-pituitary-gonadal axis 1. J Neuroendocrinol 2024:e13418. [PMID: 38852954 DOI: 10.1111/jne.13418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 03/30/2024] [Accepted: 05/15/2024] [Indexed: 06/11/2024]
Abstract
G protein-coupled receptors (GPCRs) are central to the functioning of the hypothalamic-pituitary-gonadal axis (HPG axis) and include the rhodopsin-like GPCR family members, neurokinin 3 receptor, kappa-opioid receptor, kisspeptin 1 receptor, gonadotropin-releasing hormone receptor, and the gonadotropin receptors, luteinizing hormone/choriogonadotropin receptor and follicle-stimulating hormone receptor. Unsurprisingly, inactivating variants of these receptors have been implicated in a spectrum of reproductive phenotypes, including failure to undergo puberty, and infertility. Clinical induction of puberty in patients harbouring such variants is possible, but restoration of fertility is not always a realisable outcome, particularly for those patients suffering from primary hypogonadism. Thus, novel pharmaceuticals and/or a fundamental change in approach to treating these patients are required. The increasing wealth of data describing the effects of coding-region genetic variants on GPCR function has highlighted that the majority appear to be dysfunctional as a result of misfolding of the encoded receptor protein, which, in turn, results in impaired receptor trafficking through the secretory pathway to the cell surface. As such, these intracellularly retained receptors may be amenable to 'rescue' using a pharmacological chaperone (PC)-based approach. PCs are small, cell permeant molecules hypothesised to interact with misfolded intracellularly retained proteins, stabilising their folding and promoting their trafficking through the secretory pathway. In support of the use of this approach as a viable therapeutic option, it has been observed that many rescued variant GPCRs retain at least a degree of functionality when 'rescued' to the cell surface. In this review, we examine the GPCR PC research landscape, focussing on the rescue of inactivating variant GPCRs with important roles in the HPG axis, and describe what is known regarding the mechanisms by which PCs restore trafficking and function. We also discuss some of the merits and obstacles associated with taking this approach forward into a clinical setting.
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Affiliation(s)
- Tarryn Radomsky
- Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Ross C Anderson
- Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Robert P Millar
- Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
- Faculty of Health Sciences, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Claire L Newton
- Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
- Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh, UK
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Lu C, Zhang L, Chen X, Wan H, Dong H. Cl - induces endothelium-dependent mesenteric arteriolar vasorelaxation through the NKCC1/TRPV4/NCX axis. Life Sci 2023; 330:121942. [PMID: 37451399 DOI: 10.1016/j.lfs.2023.121942] [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: 05/26/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
AIMS Although absorbed NaCl increases intestinal blood flow to facilitate absorption and transportation, it is unclear if it can directly mediate mesenteric arterial relaxation. We aimed to investigate and test our hypothesis that Cl- induces mesenteric arterial vasorelaxation via endothelium-dependent hyperpolarization (EDH). MAIN METHODS We used wire myograph to study NaCl-induced vasorelaxation of mesenteric arteries isolated from mice. Cl-, Ca2+ and K+ imaging was performed in human vascular endothelial cells pre-treated with pharmacological agents. KEY FINDINGS The Cl- concentration-dependently induced vasorelaxation of mesenteric arteries likely through EDH. The Cl--induced vasorelaxation was attenuated in TRPV4 KO mice and inhibited by selective blockers of Na+-K+-2Cl- cotransporter 1 (NKCC1) (bumetanide, 10 μM), transient receptor potential vanilloid 4 (TRPV4) (RN-1734, 40 μM), and small conductance Ca2+-activated K+ channels (SKCa) (apamin, 3 μM)/ intermediate conductance Ca2+-activated K+ channels (IKCa) (TRAM-34, 10 μM) and myoendothelial gap junction (18α-glycyrrhetinic acid, 10 μM), but enhanced by a selective activator of IKCa/SKCa (SKA-31, 0.3 μM). Cl- decreased intracellular K+ concentrations in endothelial cells, which was reversed by apamin (200 nM) plus TRAM-34 (500 nM). Extracellular Cl- raised intracellular Cl- concentrations in endothelial cells, which was attenuated by bumetanide (10 μM). Finally, Cl- induced a transient Ca2+ signaling via TRPV4 in endothelial cells, which became sustained when the Ca2+ exit mode of Na+-Ca2+ exchanger (NCX) was blocked. SIGNIFICANCE Cl- induces a pure EDH-mediated vasorelaxation of mesenteric arteries through activation of endothelial NKCC1/TRPV4/NCX axis. We have provided a novel insight into the role of Cl--induced vasorelaxation via EDH mechanism.
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Affiliation(s)
- Cheng Lu
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, #1 Ningde Road, Qingdao 266073, China; Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing 400037, China
| | - Luyun Zhang
- Department of Pediatric Intensive Care Unit, Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Xiongying Chen
- Department of Pediatric Intensive Care Unit, Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing 400037, China.
| | - Hui Dong
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, #1 Ningde Road, Qingdao 266073, China; Department of Gastroenterology, Xinqiao Hospital, Army Medical University, Chongqing 400037, China.
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3
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Salari A, Xiu R, Amiri M, Pallenberg ST, Schreiber R, Dittrich AM, Tümmler B, Kunzelmann K, Seidler U. The Anion Channel TMEM16a/Ano1 Modulates CFTR Activity, but Does Not Function as an Apical Anion Channel in Colonic Epithelium from Cystic Fibrosis Patients and Healthy Individuals. Int J Mol Sci 2023; 24:14214. [PMID: 37762516 PMCID: PMC10531629 DOI: 10.3390/ijms241814214] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
Studies in human colonic cell lines and murine intestine suggest the presence of a Ca2+-activated anion channel, presumably TMEM16a. Is there a potential for fluid secretion in patients with severe cystic fibrosis transmembrane conductance regulator (CFTR) mutations by activating this alternative pathway? Two-dimensional nondifferentiated colonoid-myofibroblast cocultures resembling transit amplifying/progenitor (TA/PE) cells, as well as differentiated monolayer (DM) cultures resembling near-surface cells, were established from both healthy controls (HLs) and patients with severe functional defects in the CFTR gene (PwCF). F508del mutant and CFTR knockout (null) mice ileal and colonic mucosa was also studied. HL TA/PE monolayers displayed a robust short-circuit current response (ΔIeq) to UTP (100 µM), forskolin (Fsk, 10 µM) and carbachol (CCH, 100 µM), while ΔIeq was much smaller in differentiated monolayers. The selective TMEM16a inhibitor Ani9 (up to 30 µM) did not alter the response to luminal UTP, significantly decreased Fsk-induced ΔIeq, and significantly increased CCH-induced ΔIeq in HL TA/PE colonoid monolayers. The PwCF TA/PE and the PwCF differentiated monolayers displayed negligible agonist-induced ΔIeq, without a significant effect of Ani9. When TMEM16a was localized in intracellular structures, a staining in the apical membrane was not detected. TMEM16a is highly expressed in human colonoid monolayers resembling transit amplifying cells of the colonic cryptal neck zone, from both HL and PwCF. While it may play a role in modulating agonist-induced CFTR-mediated anion currents, it is not localized in the apical membrane, and it has no function as an apical anion channel in cystic fibrosis (CF) and healthy human colonic epithelium.
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Affiliation(s)
- Azam Salari
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Renjie Xiu
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Mahdi Amiri
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Sophia Theres Pallenberg
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Rainer Schreiber
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany; (R.S.); (K.K.)
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Burkhard Tümmler
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Karl Kunzelmann
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany; (R.S.); (K.K.)
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
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Oliver KE, Carlon MS, Pedemonte N, Lopes-Pacheco M. The revolution of personalized pharmacotherapies for cystic fibrosis: what does the future hold? Expert Opin Pharmacother 2023; 24:1545-1565. [PMID: 37379072 PMCID: PMC10528905 DOI: 10.1080/14656566.2023.2230129] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 06/29/2023]
Abstract
INTRODUCTION Cystic fibrosis (CF), a potentially fatal genetic disease, is caused by loss-of-function mutations in the gene encoding for the CFTR chloride/bicarbonate channel. Modulator drugs rescuing mutant CFTR traffic and function are now in the clinic, providing unprecedented breakthrough therapies for people with CF (PwCF) carrying specific genotypes. However, several CFTR variants are unresponsive to these therapies. AREA COVERED We discussed several therapeutic approaches that are under development to tackle the fundamental cause of CF, including strategies targeting defective CFTR mRNA and/or protein expression and function. Alternatively, defective chloride secretion and dehydration in CF epithelia could be restored by exploiting pharmacological modulation of alternative targets, i.e., ion channels/transporters that concur with CFTR to maintain the airway surface liquid homeostasis (e.g., ENaC, TMEM16A, SLC26A4, SLC26A9, and ATP12A). Finally, we assessed progress and challenges in the development of gene-based therapies to replace or correct the mutant CFTR gene. EXPERT OPINION CFTR modulators are benefiting many PwCF responsive to these drugs, yielding substantial improvements in various clinical outcomes. Meanwhile, the CF therapy development pipeline continues to expand with the development of novel CFTR modulators and alternative therapeutic strategies with the ultimate goal of providing effective therapies for all PwCF in the foreseeable future.
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Affiliation(s)
- Kathryn E. Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
- Center for Cystic Fibrosis and Airways Disease Research, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Marianne S. Carlon
- Laboratory of Respiratory Diseases and Thoracic Surgery (BREATHE), Department of Chronic Diseases and Metabolism, KU Leuven, Leuven, Belgium
- Center for Molecular Medicine, KU Leuven, Leuven, Belgium
| | | | - Miquéias Lopes-Pacheco
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisbon, Lisbon, Portugal
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5
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Mondal A, Barik GK, Sarkar S, Mondal D, Ahmad M, Vijayakanth T, Mondal J, Santra MK, Talukdar P. Nontoxic Artificial Chloride Channel Formation in Epithelial Cells by Isophthalic Acid-Based Small Molecules. Chemistry 2023; 29:e202202887. [PMID: 36399427 DOI: 10.1002/chem.202202887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/18/2022] [Accepted: 11/18/2022] [Indexed: 11/19/2022]
Abstract
Artificial channels capable of facilitating the transport of Cl- ions across cell membranes while being nontoxic to the cells are rare. Such synthetic ion channels can mimic the functions of membrane transport proteins and, therefore, have the potential to treat channelopathies by replacing defective ion channels. Here we report isophthalic acid-based structurally simple molecules 1 a and 2 a, which self-assemble to render supramolecular nanochannels that allow selective transport of Cl- ions. As evident from the single-crystal X-ray diffraction analysis, the self-assembly is governed by intermolecular hydrogen bonding and π-π stacking interactions. The MD simulation studies for both 1 a and 2 a confirmed the formation of stable Cl- channel assembly in the lipid membrane and Cl- transport through them. The MQAE assay showed the efficacy of the compounds in delivering Cl- ions into cells, and the MTT assays proved that the compounds are nontoxic to cells even at a concentration of 100 μM.
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Affiliation(s)
- Abhishek Mondal
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, Maharashtra, India
| | | | - Susmita Sarkar
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, 500046, Telangana, India
| | - Debashis Mondal
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, Maharashtra, India
| | - Manzoor Ahmad
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, Maharashtra, India
| | - Thangavel Vijayakanth
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Jagannath Mondal
- Center for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad, 500046, Telangana, India
| | | | - Pinaki Talukdar
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, Maharashtra, India
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Mondal A, Ahmad M, Mondal D, Talukdar P. Progress and prospects toward supramolecular bioactive ion transporters. Chem Commun (Camb) 2023; 59:1917-1938. [PMID: 36691926 DOI: 10.1039/d2cc06761g] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The majority of cellular physiological processes depend on natural ion channels, which are pore-forming membrane-embedded proteins that let ions flow across the cell membranes selectively. This selective movement of ions across the membranes balances the osmolality within and outside the cell. However, mutations in the genes that encode essential membrane transport proteins or structural reorganisation of these proteins can cause life-threatening diseases like cystic fibrosis. Artificial ion transport systems have opened up a way to replace dysfunctional natural ion channels to cure such diseases through channel replacement therapy. Moreover, recent research has also demonstrated the ability of these systems to kill cancer cells, reigniting interest in the field among scientists. Our contributions to the recent progress in the design and development of artificial chloride ion transporters and their effect on biological systems have been discussed in this review. This review would provide current vistas and future directions toward the development of novel ion transporters with improved biocompatibility and desired anti-cancer properties. Additionally, it strongly emphasises stimuli-responsive ion transport systems, which are crucial for obtaining target-specificity and may speed up the application of these systems in clinical therapeutics.
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Affiliation(s)
- Abhishek Mondal
- Chemistry Department, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India.
| | - Manzoor Ahmad
- Chemistry Department, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India. .,Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, UK
| | - Debashis Mondal
- Chemistry Department, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India. .,Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Zwirkii Wigury 101, Warsaw 02-089, Poland
| | - Pinaki Talukdar
- Chemistry Department, Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, Maharashtra, India.
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7
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Åstrand A, Libby EF, Shei RJ, Lever JEP, Kaza N, Adewale AT, Boitet E, Edwards L, Hemmerling M, Root J, Lindberg B, Wingren C, Malmgren A, Sabater J, Rowe SM. Preclinical evaluation of the epithelial sodium channel inhibitor AZD5634 and implications on human translation. Am J Physiol Lung Cell Mol Physiol 2022; 323:L536-L547. [PMID: 36098422 PMCID: PMC9602792 DOI: 10.1152/ajplung.00454.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Airway dehydration causes mucus stasis and bacterial overgrowth in cystic fibrosis (CF), resulting in recurrent respiratory infections and exacerbations. Strategies to rehydrate airway mucus including inhibition of the epithelial sodium channel (ENaC) have the potential to improve mucosal defense by enhancing mucociliary clearance (MCC) and reducing the risk of progressive decline in lung function. In the current work, we evaluated the effects of AZD5634, an ENaC inhibitor that shows extended lung retention and safety profile as compared with previously evaluated candidate drugs, in healthy and CF preclinical model systems. We found that AZD5634 elicited a potent inhibition of amiloride-sensitive current in non-CF airway cells and airway cells derived from F508del-homozygous individuals with CF that effectively increased airway surface liquid volume and improved mucociliary transport (MCT) rate. AZD5634 also demonstrated efficacious inhibition of ENaC in sheep bronchial epithelial cells, translating to dose-dependent improvement of mucus clearance in healthy sheep in vivo. Conversely, nebulization of AZD5634 did not notably improve airway hydration or MCT in CF rats that exhibit an MCC defect, consistent with findings from a first single-dose evaluation of AZD5634 on MCC in people with CF. Overall, these findings suggest that CF animal models demonstrating impaired mucus clearance translatable to the human situation may help to successfully predict and promote the successful translation of ENaC-directed therapies to the clinic.
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Affiliation(s)
- Annika Åstrand
- 1Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Emily Falk Libby
- 2Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Ren-Jay Shei
- 2Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama,3Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jacelyn E. Peabody Lever
- 2Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama,3Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Niroop Kaza
- 3Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | | | - Evan Boitet
- 2Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Lloyd Edwards
- 4Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Martin Hemmerling
- 1Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - James Root
- 1Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Botilda Lindberg
- 1Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Cecilia Wingren
- 1Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Anna Malmgren
- 1Research and Early Development, Respiratory & Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | | | - Steven M. Rowe
- 2Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama,3Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama,5Department of Cellular, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama,6Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama
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8
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Rehman T, Karp PH, Thurman AL, Mather SE, Jain A, Cooney AL, Sinn PL, Pezzulo AA, Duffey ME, Welsh MJ. WNK Inhibition Increases Surface Liquid pH and Host Defense in Cystic Fibrosis Airway Epithelia. Am J Respir Cell Mol Biol 2022; 67:491-502. [PMID: 35849656 PMCID: PMC9564924 DOI: 10.1165/rcmb.2022-0172oc] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 07/18/2022] [Indexed: 02/05/2023] Open
Abstract
In cystic fibrosis (CF), reduced HCO3- secretion acidifies the airway surface liquid (ASL), and the acidic pH disrupts host defenses. Thus, understanding the control of ASL pH (pHASL) in CF may help identify novel targets and facilitate therapeutic development. In diverse epithelia, the WNK (with-no-lysine [K]) kinases coordinate HCO3- and Cl- transport, but their functions in airway epithelia are poorly understood. Here, we tested the hypothesis that WNK kinases regulate CF pHASL. In primary cultures of differentiated human airway epithelia, inhibiting WNK kinases acutely increased both CF and non-CF pHASL. This response was HCO3- dependent and involved downstream SPAK/OSR1 (Ste20/SPS1-related proline-alanine-rich protein kinase/oxidative stress responsive 1 kinase). Importantly, WNK inhibition enhanced key host defenses otherwise impaired in CF. Human airway epithelia expressed two WNK isoforms in secretory cells and ionocytes, and knockdown of either WNK1 or WNK2 increased CF pHASL. WNK inhibition decreased Cl- secretion and the response to bumetanide, an NKCC1 (sodium-potassium-chloride cotransporter 1) inhibitor. Surprisingly, bumetanide alone or basolateral Cl- substitution also alkalinized CF pHASL. These data suggest that WNK kinases influence the balance between transepithelial Cl- versus HCO3- secretion. Moreover, reducing basolateral Cl- entry may increase HCO3- secretion and raise pHASL, thereby improving CF host defenses.
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Affiliation(s)
| | - Philip H. Karp
- Department of Internal Medicine and
- Howard Hughes Medical Institute, University of Iowa, Iowa City, Iowa; and
| | | | | | | | | | | | | | - Michael E. Duffey
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York
| | - Michael J. Welsh
- Department of Internal Medicine and
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, and
- Howard Hughes Medical Institute, University of Iowa, Iowa City, Iowa; and
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9
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Amaral MD. Using the genome to correct the ion transport defect in cystic fibrosis. J Physiol 2022; 601:1573-1582. [PMID: 36068724 DOI: 10.1113/jp282308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/31/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Human genome information can help finding drugs for human diseases. 'Omics' allow unbiased identification of novel drug targets. High-throughput (HT) approaches provide a global view on disease mechanisms. As a monogenic disease CF has led the way in multiple 'Omic' studies. 'Multi-omics' integration will generate maximal biological significance. ABSTRACT Today Biomedicine faces one of its greatest challenges, i.e. treating diseases through their causative dysfunctional processes and not just their symptoms. However, we still miss a global view of mechanisms and pathways involved in pathophysiology of most diseases. In fact, disease mechanisms and pathways can be achieved by holistic studies provided by 'Omic' approaches. Cystic Fibrosis (CF), caused by mutations in the CF transmembrane conductance regulator (CFTR) gene which encodes an anion channel, is paradigmatic for monogenic disorders, namely channelopathies. A high number of 'omics studies' have focussed on CF, namely several cell-based high-throughput (HT) approaches were developed and applied towards a global mechanistic characterization of CF pathophysiology and the identification of novel and 'unbiased' drug targets. Notwithstanding, it is likely that, through the integration of all these 'layers' of large datasets into comprehensive disease maps that biological significance can be extracted so that the enormous potential of these approaches to identifying dysfunctional mechanisms and novel drugs may become a reality. Abstract figure legend Schematic overview of the 3 main approaches to discovery of new drugs/drug targets. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Margarida D Amaral
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande-C8 bdg, Lisboa, 1749-016, Portugal
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Vavilova AA, Shiabiev IE, Padnya PL, Zelenikhin PV, Subakaeva EV, Stoikov II. Thiacalix[4]arenes Containing Amide and Phenylurea Fragments at the Lower Rim: Synthesis and Complexing Properties Toward Anionic Substrates. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2022. [DOI: 10.1134/s1070428022080085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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Galietta LJ. TMEM16A (ANO1) as a therapeutic target in cystic fibrosis. Curr Opin Pharmacol 2022; 64:102206. [DOI: 10.1016/j.coph.2022.102206] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 01/02/2023]
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12
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Lam AKM, Rutz S, Dutzler R. Inhibition mechanism of the chloride channel TMEM16A by the pore blocker 1PBC. Nat Commun 2022; 13:2798. [PMID: 35589730 PMCID: PMC9120017 DOI: 10.1038/s41467-022-30479-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 04/29/2022] [Indexed: 11/09/2022] Open
Abstract
TMEM16A, a calcium-activated chloride channel involved in multiple cellular processes, is a proposed target for diseases such as hypertension, asthma, and cystic fibrosis. Despite these therapeutic promises, its pharmacology remains poorly understood. Here, we present a cryo-EM structure of TMEM16A in complex with the channel blocker 1PBC and a detailed functional analysis of its inhibition mechanism. A pocket located external to the neck region of the hourglass-shaped pore is responsible for open-channel block by 1PBC and presumably also by its structural analogs. The binding of the blocker stabilizes an open-like conformation of the channel that involves a rearrangement of several pore helices. The expansion of the outer pore enhances blocker sensitivity and enables 1PBC to bind at a site within the transmembrane electric field. Our results define the mechanism of inhibition and gating and will facilitate the design of new, potent TMEM16A modulators.
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Affiliation(s)
- Andy K M Lam
- Department of Biochemistry, University of Zurich, Winterthurer Str. 190, CH-8057, Zurich, Switzerland.
| | - Sonja Rutz
- Department of Biochemistry, University of Zurich, Winterthurer Str. 190, CH-8057, Zurich, Switzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Winterthurer Str. 190, CH-8057, Zurich, Switzerland.
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13
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SLC26A9 is selected for endoplasmic reticulum associated degradation (ERAD) via Hsp70-dependent targeting of the soluble STAS domain. Biochem J 2021; 478:4203-4220. [PMID: 34821356 PMCID: PMC8826537 DOI: 10.1042/bcj20210644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 12/24/2022]
Abstract
SLC26A9, a member of the solute carrier protein family, transports chloride ions across various epithelia. SLC26A9 also associates with other ion channels and transporters linked to human health, and in some cases these heterotypic interactions are essential to support the biogenesis of both proteins. Therefore, understanding how this complex membrane protein is initially folded might provide new therapeutic strategies to overcome deficits in the function of SLC26A9 partners, one of which is associated with Cystic Fibrosis. To this end, we developed a novel yeast expression system for SLC26A9. This facile system has been used extensively with other ion channels and transporters to screen for factors that oversee protein folding checkpoints. As commonly observed for other channels and transporters, we first noted that a substantial fraction of SLC26A9 is targeted for endoplasmic reticulum associated degradation (ERAD), which destroys folding-compromised proteins in the early secretory pathway. We next discovered that ERAD selection requires the Hsp70 chaperone, which can play a vital role in ERAD substrate selection. We then created SLC26A9 mutants and found that the transmembrane-rich domain of SLC26A9 was quite stable, whereas the soluble cytosolic STAS domain was responsible for Hsp70-dependent ERAD. To support data obtained in the yeast model, we were able to recapitulate Hsp70-facilitated ERAD of the STAS domain in human tissue culture cells. These results indicate that a critical barrier to nascent membrane protein folding can reside within a specific soluble domain, one that is monitored by components associated with the ERAD machinery.
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Laselva O, Guerra L, Castellani S, Favia M, Di Gioia S, Conese M. Small-molecule drugs for cystic fibrosis: Where are we now? Pulm Pharmacol Ther 2021; 72:102098. [PMID: 34793977 DOI: 10.1016/j.pupt.2021.102098] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/24/2021] [Accepted: 11/12/2021] [Indexed: 01/05/2023]
Abstract
The cystic fibrosis (CF) lung disease is due to the lack/dysfunction of the CF Transmembrane Conductance Regulator (CFTR), a chloride channel expressed by epithelial cells as the main regulator of ion and fluid homeostasis. More than 2000 genetic variation in the CFTR gene are known, among which those with identified pathomechanism have been divided into six VI mutation classes. A major advancement in the pharmacotherapy of CF has been the development of small-molecule drugs hitting the root of the disease, i.e. the altered ion and fluid transport through the airway epithelium. These drugs, called CFTR modulators, have been advanced to the clinics to treat nearly 90% of CF patients, including the CFTR potentiator ivacaftor, approved for residual function mutations (Classes III and IV), and combinations of correctors (lumacaftor, tezacaftor, elexacaftor) and ivacaftor for patients bearing at least one the F508del mutation, the most frequent mutation belonging to class II. To cover the 10% of CF patients without etiological therapies, other novel small-molecule CFTR modulators are in evaluation of their effectiveness in all the CFTR mutation classes: read-through agents for Class I, correctors, potentiators and amplifiers from different companies for Class II-V, stabilizers for Class VI. In alternative, other solute carriers, such as SLC26A9 and SLC6A14, are the focus of intensive investigation. Finally, other molecular targets are being evaluated for patients with no approved CFTR modulator therapy or as means of enhancing CFTR modulatory therapy, including small molecules forming ion channels, inhibitors of the ENaC sodium channel and potentiators of the calcium-activated chloride channel TMEM16A. This paper aims to give an up-to-date overview of old and novel CFTR modulators as well as of novel strategies based on small-molecule drugs. Further investigations in in-vivo and cell-based models as well as carrying out large prospective studies will be required to determine if novel CFTR modulators, stabilizers, amplifiers, and the ENaC inhibitors or TMEM16A potentiators will further improve the clinical outcomes in CF management.
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Affiliation(s)
- Onofrio Laselva
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Lorenzo Guerra
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Stefano Castellani
- Department of Medical Sciences and Human Oncology, University of Bari, Bari, Italy
| | - Maria Favia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Sante Di Gioia
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Massimo Conese
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy.
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TMEM16A/ANO1: Current Strategies and Novel Drug Approaches for Cystic Fibrosis. Cells 2021; 10:cells10112867. [PMID: 34831090 PMCID: PMC8616501 DOI: 10.3390/cells10112867] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/19/2022] Open
Abstract
Cystic fibrosis (CF) is the most common of rare hereditary diseases in Caucasians, and it is estimated to affect 75,000 patients globally. CF is a complex disease due to the multiplicity of mutations found in the CF transmembrane conductance regulator (CFTR) gene causing the CFTR protein to become dysfunctional. Correctors and potentiators have demonstrated good clinical outcomes for patients with specific gene mutations; however, there are still patients for whom those treatments are not suitable and require alternative CFTR-independent strategies. Although CFTR is the main chloride channel in the lungs, others could, e.g., anoctamin-1 (ANO1 or TMEM16A), compensate for the deficiency of CFTR. This review summarizes the current knowledge on calcium-activated chloride channel (CaCC) ANO1 and presents ANO1 as an exciting target in CF.
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Pinto MC, Silva IAL, Figueira MF, Amaral MD, Lopes-Pacheco M. Pharmacological Modulation of Ion Channels for the Treatment of Cystic Fibrosis. J Exp Pharmacol 2021; 13:693-723. [PMID: 34326672 PMCID: PMC8316759 DOI: 10.2147/jep.s255377] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/30/2021] [Indexed: 12/12/2022] Open
Abstract
Cystic fibrosis (CF) is a life-shortening monogenic disease caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein, an anion channel that transports chloride and bicarbonate across epithelia. Despite clinical progress in delaying disease progression with symptomatic therapies, these individuals still develop various chronic complications in lungs and other organs, which significantly restricts their life expectancy and quality of life. The development of high-throughput assays to screen drug-like compound libraries have enabled the discovery of highly effective CFTR modulator therapies. These novel therapies target the primary defect underlying CF and are now approved for clinical use for individuals with specific CF genotypes. However, the clinically approved modulators only partially reverse CFTR dysfunction and there is still a considerable number of individuals with CF carrying rare CFTR mutations who remain without any effective CFTR modulator therapy. Accordingly, additional efforts have been pursued to identify novel and more potent CFTR modulators that may benefit a larger CF population. The use of ex vivo individual-derived specimens has also become a powerful tool to evaluate novel drugs and predict their effectiveness in a personalized medicine approach. In addition to CFTR modulators, pro-drugs aiming at modulating alternative ion channels/transporters are under development to compensate for the lack of CFTR function. These therapies may restore normal mucociliary clearance through a mutation-agnostic approach (ie, independent of CFTR mutation) and include inhibitors of the epithelial sodium channel (ENaC), modulators of the calcium-activated channel transmembrane 16A (TMEM16, or anoctamin 1) or of the solute carrier family 26A member 9 (SLC26A9), and anionophores. The present review focuses on recent progress and challenges for the development of ion channel/transporter-modulating drugs for the treatment of CF.
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Affiliation(s)
- Madalena C Pinto
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Lisboa, Portugal
| | - Iris A L Silva
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Lisboa, Portugal
| | - Miriam F Figueira
- Marsico Lung Institute/Cystic Fibrosis Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Margarida D Amaral
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Lisboa, Portugal
| | - Miquéias Lopes-Pacheco
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisboa, Lisboa, Portugal
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Lopes-Pacheco M, Pedemonte N, Veit G. Discovery of CFTR modulators for the treatment of cystic fibrosis. Expert Opin Drug Discov 2021; 16:897-913. [PMID: 33823716 DOI: 10.1080/17460441.2021.1912732] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Cystic fibrosis (CF) is a life-threatening inherited disease caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) protein, an anion channel expressed at the apical membrane of secretory epithelia. CF leads to multiorgan dysfunction with progressive deterioration of lung function being the major cause of untimely death. Conventional CF therapies target only symptoms and consequences downstream of the primary genetic defect and the current life expectancy and quality of life of these individuals are still very limited. AREA COVERED CFTR modulator drugs are novel-specialized therapies that enhance or even restore functional expression of CFTR mutants and have been approved for clinical use for individuals with specific CF genotypes. This review summarizes classical approaches used for the pre-clinical development of CFTR correctors and potentiators as well as emerging strategies aiming to accelerate modulator development and expand theratyping efforts. EXPERT OPINION Highly effective CFTR modulator drugs are expected to deeply modify the disease course for the majority of individuals with CF. A multitude of experimental approaches have been established to accelerate the development of novel modulators. CF patient-derived specimens are valuable cell models to predict therapeutic effectiveness of existing (and novel) modulators in a precision medicine approach.
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Affiliation(s)
| | | | - Guido Veit
- Department of Physiology, McGill University, Montréal, Canada
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McMahon DB, Carey RM, Kohanski MA, Adappa ND, Palmer JN, Lee RJ. PAR-2-activated secretion by airway gland serous cells: role for CFTR and inhibition by Pseudomonas aeruginosa. Am J Physiol Lung Cell Mol Physiol 2021; 320:L845-L879. [PMID: 33655758 DOI: 10.1152/ajplung.00411.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Airway submucosal gland serous cells are important sites of fluid secretion in conducting airways. Serous cells also express the cystic fibrosis (CF) transmembrane conductance regulator (CFTR). Protease-activated receptor 2 (PAR-2) is a G protein-coupled receptor that activates secretion from intact airway glands. We tested if and how human nasal serous cells secrete fluid in response to PAR-2 stimulation using Ca2+ imaging and simultaneous differential interference contrast imaging to track isosmotic cell shrinking and swelling reflecting activation of solute efflux and influx pathways, respectively. During stimulation of PAR-2, serous cells exhibited dose-dependent increases in intracellular Ca2+. At stimulation levels >EC50 for Ca2+, serous cells simultaneously shrank ∼20% over ∼90 s due to KCl efflux reflecting Ca2+-activated Cl- channel (CaCC, likely TMEM16A)-dependent secretion. At lower levels of PAR-2 stimulation (<EC50 for Ca2+), shrinkage was not evident due to failure to activate CaCC. Low levels of cAMP-elevating VIP receptor (VIPR) stimulation, also insufficient to activate secretion alone, synergized with low-level PAR-2 stimulation to elicit fluid secretion dependent on both cAMP and Ca2+ to activate CFTR and K+ channels, respectively. Polarized cultures of primary serous cells also exhibited synergistic fluid secretion. Pre-exposure to Pseudomonas aeruginosa conditioned media inhibited PAR-2 activation by proteases but not peptide agonists in primary nasal serous cells, Calu-3 bronchial cells, and primary nasal ciliated cells. Disruption of synergistic CFTR-dependent PAR-2/VIPR secretion may contribute to reduced airway surface liquid in CF. Further disruption of the CFTR-independent component of PAR-2-activated secretion by P. aeruginosa may also be important to CF pathophysiology.
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Affiliation(s)
- Derek B McMahon
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Ryan M Carey
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Michael A Kohanski
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Nithin D Adappa
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - James N Palmer
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Robert J Lee
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.,Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
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Salomon JJ, Albrecht T, Graeber SY, Scheuermann H, Butz S, Schatterny J, Mairbäurl H, Baumann I, Mall MA. Chronic rhinosinusitis with nasal polyps is associated with impaired TMEM16A-mediated epithelial chloride secretion. J Allergy Clin Immunol 2021; 147:2191-2201.e2. [PMID: 33609628 DOI: 10.1016/j.jaci.2021.02.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 01/16/2021] [Accepted: 02/12/2021] [Indexed: 01/10/2023]
Abstract
BACKGROUND Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the most common chronic disorders with limited therapeutic options. However, the pathogenesis of CRSwNP remains poorly understood. OBJECTIVE We sought to determine the role of abnormalities in nasal epithelial ion transport in primary epithelial cultures and patients with CRSwNP. METHODS We studied epithelial ion transport and transcript levels of the Cl- channels cystic fibrosis transmembrane conductance regulator and transmembrane protein 16A (TMEM16A) in human primary nasal epithelial cultures of patients with CRSwNP and healthy controls. Furthermore, we determined expression levels of proinflammatory cytokines that have been implicated in the regulation of epithelial ion channels (IL-1β, INF-γ, TNF-α, IL-13) and studied effects of the key TH2 signaling molecule IL-13 in CRSwNP and control nasal epithelial cultures. Finally, we measured in vivo nasal potential difference to compare epithelial ion transport in patients with CRSwNP and controls. RESULTS Bioelectric studies demonstrated that Ca2+-activated Cl- secretion was reduced in CRSwNP versus control nasal epithelial cultures. Transcript levels of IL-13 and the Ca2+-activated Cl- channel TMEM16A were increased in CRSwNP cultures. Stimulation with IL-13 increased TMEM16A expression further and restored Ca2+-activated Cl- secretion in CRSwNP cultures. Nasal potential difference measurements demonstrated reduced Ca2+-activated Cl- transport in patients with CRSwNP versus controls. CONCLUSIONS This study demonstrates that TMEM16A-mediated Ca2+-activated Cl- secretion is reduced in primary nasal epithelial cultures and nasal epithelia of patients with CRSwNP. Our data suggest that the Ca2+-activated Cl- channel TMEM16A may be implicated in the pathogenesis and serve as a novel therapeutic target in patients with CRSwNP.
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Affiliation(s)
- Johanna J Salomon
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Tobias Albrecht
- Department of Otolaryngology, Head and Neck Surgery, University of Heidelberg, Heidelberg, Germany
| | - Simon Y Graeber
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany; Department of Pediatric Pulmonology, Immunology and Critical Care Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany; German Centre for Lung Research (DZL), associated partner site, Berlin, Germany
| | - Heike Scheuermann
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Simone Butz
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Jolanthe Schatterny
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Heimo Mairbäurl
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Ingo Baumann
- Department of Otolaryngology, Head and Neck Surgery, University of Heidelberg, Heidelberg, Germany
| | - Marcus A Mall
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany; Department of Pediatric Pulmonology, Immunology and Critical Care Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany; German Centre for Lung Research (DZL), associated partner site, Berlin, Germany.
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20
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Lam AKM, Rheinberger J, Paulino C, Dutzler R. Gating the pore of the calcium-activated chloride channel TMEM16A. Nat Commun 2021; 12:785. [PMID: 33542223 PMCID: PMC7862301 DOI: 10.1038/s41467-020-20787-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 12/16/2020] [Indexed: 02/07/2023] Open
Abstract
The binding of cytoplasmic Ca2+ to the anion-selective channel TMEM16A triggers a conformational change around its binding site that is coupled to the release of a gate at the constricted neck of an hourglass-shaped pore. By combining mutagenesis, electrophysiology, and cryo-electron microscopy, we identified three hydrophobic residues at the intracellular entrance of the neck as constituents of this gate. Mutation of each of these residues increases the potency of Ca2+ and results in pronounced basal activity. The structure of an activating mutant shows a conformational change of an α-helix that contributes to Ca2+ binding as a likely cause for the basal activity. Although not in physical contact, the three residues are functionally coupled to collectively contribute to the stabilization of the gate in the closed conformation of the pore, thus explaining the low open probability of the channel in the absence of Ca2+.
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Affiliation(s)
- Andy K M Lam
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
| | - Jan Rheinberger
- Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Cristina Paulino
- Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
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21
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Tan Q, di Stefano G, Tan X, Renjie X, Römermann D, Talbot SR, Seidler UE. Inhibition of Na + /H + exchanger isoform 3 improves gut fluidity and alkalinity in cystic fibrosis transmembrane conductance regulator-deficient and F508del mutant mice. Br J Pharmacol 2021; 178:1018-1036. [PMID: 33179259 DOI: 10.1111/bph.15323] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 11/01/2020] [Accepted: 11/02/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Constipation and intestinal obstructive episodes are major health problems in cystic fibrosis (CF) patients. Three FDA-approved drugs against constipation-prone irritable bowel syndrome were tested for their ability to increase luminal fluidity and alkalinity in cystic fibrosis transmembrane conductance regulator (CFTR) null (cftr-/- ) and F508del mutant (F508delmut/mut ) murine intestine. EXPERIMENTAL APPROACH Guanylate cyclase C agonist linaclotide, PGE1 analogue lubiprostone and intestine-specific NHE3 inhibitor tenapanor were perfused through a ~3 cm jejunal, proximal or mid-distal colonic segment in anaesthetized cftr-/- , F508delmut/mut and WT mice. Net fluid balance was determined gravimetrically and alkaline output by pH-stat back titration. KEY RESULTS Basal jejunal fluid absorptive rates were significantly higher and basal HCO3 - output was significantly lower in cftr-/- and F508delmut/mut compared to WT mice. In cftr-/- and F508delmut/mut mice, all three drugs significantly inhibited the fluid absorptive rate and increased alkaline output in the jejunum and tenapanor and lubiprostone, but not linaclotide, in the colon. After tenapanor pre-incubation, linaclotide elicited a robust fluid secretory response in WT jejunum, while no further change in absorptive rates was observed in cftr-/- and F508delmut/mut jejunum, suggesting that the increase in gut fluidity and alkalinity by linaclotide in CF gut is mediated via NHE3 inhibition. Lubiprostone also inhibited fluid absorption in cftr-/- and F508delmut/mut jejunum via NHE3 inhibition but had a residual NHE3-independent effect. CONCLUSION AND IMPLICATIONS Linaclotide, lubiprostone and tenapanor reduced fluid absorption and increased alkaline output in the CF gut. Their application may ameliorate constipation and reduce obstructive episodes in CF patients.
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Affiliation(s)
- Qinghai Tan
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | | | - Xinjie Tan
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | - Xiu Renjie
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | - Dorothee Römermann
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | - Steven R Talbot
- Institute of Veterinary Research, Hannover Medical School, Hanover, Germany
| | - Ursula E Seidler
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
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Amaral MD. How to determine the mechanism of action of CFTR modulator compounds: A gateway to theranostics. Eur J Med Chem 2020; 210:112989. [PMID: 33190956 DOI: 10.1016/j.ejmech.2020.112989] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/02/2020] [Accepted: 11/02/2020] [Indexed: 12/12/2022]
Abstract
The greatest challenge of 21st century biology is to fully understand mechanisms of disease to drive new approaches and medical innovation. Parallel to this is the huge biomedical endeavour of treating people through personalized medicine. Until now all CFTR modulator drugs that have entered clinical trials have been genotype-dependent. An emerging alternative is personalized/precision medicine in CF, i.e., to determine whether rare CFTR mutations respond to existing (or novel) CFTR modulator drugs by pre-assessing them directly on patient's tissues ex vivo, an approach also now termed theranostics. To administer the right drug to the right person it is essential to understand how drugs work, i.e., to know their mechanism of action (MoA), so as to predict their applicability, not just in certain mutations but also possibly in other diseases that share the same defect/defective pathway. Moreover, an understanding the MoA of a drug before it is tested in clinical trials is the logical path to drug discovery and can increase its chance for success and hence also approval. In conclusion, the most powerful approach to determine the MoA of a compound is to understand the underlying biology. Novel large datasets of intervenients in most biological processes, namely those emerging from the post-genomic era tools, are available and should be used to help in this task.
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Affiliation(s)
- Margarida D Amaral
- BioISI - Biosystems & Integrative Sciences Institute, Lisboa, Faculty of Sciences, University of Lisboa, Portugal.
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23
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Editorial: Special Issue on "Therapeutic Approaches for Cystic Fibrosis". Int J Mol Sci 2020; 21:ijms21186657. [PMID: 32932926 PMCID: PMC7555172 DOI: 10.3390/ijms21186657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 12/18/2022] Open
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Laselva O, Bartlett C, Popa A, Ouyang H, Gunawardena TNA, Gonska T, Moraes TJ, Bear CE. Emerging preclinical modulators developed for F508del-CFTR have the potential to be effective for ORKAMBI resistant processing mutants. J Cyst Fibros 2020; 20:106-119. [PMID: 32741662 DOI: 10.1016/j.jcf.2020.07.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 07/07/2020] [Accepted: 07/22/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND F508del is prototypical of Class 2 CFTR mutations associated with protein misprocessing and reduced function. Corrector compounds like lumacaftor partially rescue the processing defect of F508del-CFTR whereas potentiators like ivacaftor, enhance its channel activity once trafficked to the cell surface. We asked if emerging modulators developed for F508del-CFTR can rescue Class 2 mutations previously shown to be poorly responsive to lumacaftor and ivacaftor. METHODS Rescue of mutant CFTRs by the correctors: AC1, AC2-1 or AC2-2 and the potentiator, AP2, was studied in HEK-293 cells and in primary human nasal epithelial (HNE) cultures, using a membrane potential assay and Ussing chamber, respectively. RESULTS In HEK-293 cells, we found that a particular combination of corrector molecules (AC1 plus AC2-1) and a potentiator (AP2) was effective in rescuing both the misprocessing and reduced function of M1101K and G85E respectively. These findings were recapitulated in patient-derived nasal cultures, although another corrector combination, AC1 plus AC2-2 also improved misprocessing in these primary tissues. Interestingly, while this corrector combination only led to a modest increase in the abundance of mature N1303K-CFTR it did enable its functional expression in the presence of the potentiator, AP2, in part, because the nominal corrector, AC2-2 also exhibits potentiator activity. CONCLUSIONS Strategic combinations of novel modulators can potentially rescue Class 2 mutants thought to be relatively unresponsive to lumacaftor and ivacaftor.
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Affiliation(s)
- Onofrio Laselva
- Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada
| | - Claire Bartlett
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada
| | - Alec Popa
- Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada
| | - Hong Ouyang
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada
| | | | - Tanja Gonska
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada; Department of Paediatrics, University of Toronto, Toronto, Canada
| | - Theo J Moraes
- Programme in Translational Medicine, Hospital for Sick Children, Toronto, Canada; Department of Paediatrics, University of Toronto, Toronto, Canada
| | - Christine E Bear
- Programme in Molecular Medicine, Hospital for Sick Children, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada.
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Davis JT, Gale PA, Quesada R. Advances in anion transport and supramolecular medicinal chemistry. Chem Soc Rev 2020; 49:6056-6086. [PMID: 32692794 DOI: 10.1039/c9cs00662a] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Advances in anion transport by synthetic supramolecular systems are discussed in this article. Developments in the design of discrete molecular carriers for anions and supramolecular anion channels are reviewed followed by an overview of the use of these systems in biological systems as putative treatments for diseases such as cystic fibrosis and cancer.
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Affiliation(s)
- Jeffery T Davis
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
| | - Philip A Gale
- School of Chemistry (F11), The University of Sydney, NSW 2006, Australia.
| | - Roberto Quesada
- Departmento de Química, Universidad de Burgos, 09001 Burgos, Spain.
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Rehman T, Thornell IM, Pezzulo AA, Thurman AL, Romano Ibarra GS, Karp PH, Tan P, Duffey ME, Welsh MJ. TNFα and IL-17 alkalinize airway surface liquid through CFTR and pendrin. Am J Physiol Cell Physiol 2020; 319:C331-C344. [PMID: 32432926 PMCID: PMC7500220 DOI: 10.1152/ajpcell.00112.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The pH of airway surface liquid (ASL) is a key factor that determines respiratory host defense; ASL acidification impairs and alkalinization enhances key defense mechanisms. Under healthy conditions, airway epithelia secrete base ([Formula: see text]) and acid (H+) to control ASL pH (pHASL). Neutrophil-predominant inflammation is a hallmark of several airway diseases, and TNFα and IL-17 are key drivers. However, how these cytokines perturb pHASL regulation is uncertain. In primary cultures of differentiated human airway epithelia, TNFα decreased and IL-17 did not change pHASL. However, the combination (TNFα+IL-17) markedly increased pHASL by increasing [Formula: see text] secretion. TNFα+IL-17 increased expression and function of two apical [Formula: see text] transporters, CFTR anion channels and pendrin Cl-/[Formula: see text] exchangers. Both were required for maximal alkalinization. TNFα+IL-17 induced pendrin expression primarily in secretory cells where it was coexpressed with CFTR. Interestingly, significant pendrin expression was not detected in CFTR-rich ionocytes. These results indicate that TNFα+IL-17 stimulate [Formula: see text] secretion via CFTR and pendrin to alkalinize ASL, which may represent an important defense mechanism in inflamed airways.
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Affiliation(s)
- Tayyab Rehman
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ian M Thornell
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Alejandro A Pezzulo
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Andrew L Thurman
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Guillermo S Romano Ibarra
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Philip H Karp
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ping Tan
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Michael E Duffey
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York
| | - Michael J Welsh
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa
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27
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TMEM16A: An Alternative Approach to Restoring Airway Anion Secretion in Cystic Fibrosis? Int J Mol Sci 2020; 21:ijms21072386. [PMID: 32235608 PMCID: PMC7177896 DOI: 10.3390/ijms21072386] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/26/2020] [Accepted: 03/27/2020] [Indexed: 12/18/2022] Open
Abstract
The concept that increasing airway hydration leads to improvements in mucus clearance and lung function in cystic fibrosis has been clinically validated with osmotic agents such as hypertonic saline and more convincingly with cystic fibrosis transmembrane conductance regulator (CFTR) repair therapies. Although rapidly becoming the standard of care in cystic fibrosis (CF), current CFTR modulators do not treat all patients nor do they restore the rate of decline in lung function to normal levels. As such, novel approaches are still required to ensure all with CF have effective therapies. Although CFTR plays a fundamental role in the regulation of fluid secretion across the airway mucosa, there are other ion channels and transporters that represent viable targets for future therapeutics. In this review article we will summarise the current progress with CFTR-independent approaches to restoring mucosal hydration, including epithelial sodium channel (ENaC) blockade and modulators of SLC26A9. A particular emphasis is given to modulation of the airway epithelial calcium-activated chloride channel (CaCC), TMEM16A, as there is controversy regarding whether it should be positively or negatively modulated. This is discussed in light of a recent report describing for the first time bona fide TMEM16A potentiators and their positive effects upon epithelial fluid secretion and mucus clearance.
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28
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Small Molecule Anion Carriers Correct Abnormal Airway Surface Liquid Properties in Cystic Fibrosis Airway Epithelia. Int J Mol Sci 2020; 21:ijms21041488. [PMID: 32098269 PMCID: PMC7073096 DOI: 10.3390/ijms21041488] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/17/2020] [Accepted: 02/19/2020] [Indexed: 01/03/2023] Open
Abstract
Cystic fibrosis (CF) is a genetic disease characterized by the lack of cystic fibrosis transmembrane conductance regulator (CFTR) protein expressed in epithelial cells. The resulting defective chloride and bicarbonate secretion and imbalance of the transepithelial homeostasis lead to abnormal airway surface liquid (ASL) composition and properties. The reduced ASL volume impairs ciliary beating with the consequent accumulation of sticky mucus. This situation prevents the normal mucociliary clearance, favouring the survival and proliferation of bacteria and contributing to the genesis of CF lung disease. Here, we have explored the potential of small molecules capable of facilitating the transmembrane transport of chloride and bicarbonate in order to replace the defective transport activity elicited by CFTR in CF airway epithelia. Primary human bronchial epithelial cells obtained from CF and non-CF patients were differentiated into a mucociliated epithelia in order to assess the effects of our compounds on some key properties of ASL. The treatment of these functional models with non-toxic doses of the synthetic anionophores improved the periciliary fluid composition, reducing the fluid re-absorption, correcting the ASL pH and reducing the viscosity of the mucus, thus representing promising drug candidates for CF therapy.
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29
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Berry KN, Brett TJ. Structural and Biophysical Analysis of the CLCA1 VWA Domain Suggests Mode of TMEM16A Engagement. Cell Rep 2020; 30:1141-1151.e3. [PMID: 31995732 PMCID: PMC7050472 DOI: 10.1016/j.celrep.2019.12.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/14/2019] [Accepted: 12/16/2019] [Indexed: 01/09/2023] Open
Abstract
The secreted protein calcium-activated chloride channel regulator 1 (CLCA1) utilizes a von Willebrand factor type A (VWA) domain to bind to and potentiate the calcium-activated chloride channel TMEM16A. To gain insight into this unique potentiation mechanism, we determined the 2.0-Å crystal structure of human CLCA1 VWA bound to Ca2+. The structure reveals the metal-ion-dependent adhesion site (MIDAS) in a high-affinity "open" conformation, engaging in crystal contacts that likely mimic how CLCA1 engages TMEM16A. The CLCA1 VWA contains a disulfide bond between α3 and α4 in close proximity to the MIDAS that is invariant in the CLCA family and unique in VWA structures. Further biophysical studies indicate that CLCA1 VWA is preferably stabilized by Mg2+ over Ca2+ and that α6 atypically extends from the VWA core. Finally, an analysis of TMEM16A structures suggests residues likely to mediate interaction with CLCA1 VWA.
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Affiliation(s)
- Kayla N Berry
- Immunology Program and Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Internal Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tom J Brett
- Department of Internal Medicine, Division of Pulmonary and Critical Care, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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30
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Danielsson J, Kuforiji AS, Yocum GT, Zhang Y, Xu D, Gallos G, Emala CW. Agonism of the TMEM16A calcium-activated chloride channel modulates airway smooth muscle tone. Am J Physiol Lung Cell Mol Physiol 2019; 318:L287-L295. [PMID: 31747299 DOI: 10.1152/ajplung.00552.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
TMEM16A (anoctamin 1) is an important calcium-activated chloride channel in airway smooth muscle (ASM). We have previously shown that TMEM16A antagonists such as benzbromarone relax ASM and have proposed TMEM16A antagonists as novel therapies for asthma treatment. However, TMEM16A is also expressed on airway epithelium, and TMEM16A agonists are being investigated as novel therapies for cystic fibrosis. There are theoretical concerns that agonism of TMEM16A on ASM could lead to bronchospasm, making them detrimental as airway therapeutics. The TMEM16A agonist Eact induced a significant contraction of human ASM and guinea pig tracheal rings in an ex vivo organ bath model. Pretreatment with two different TMEM16A antagonists, benzbromarone or T16Ainh-A01, completely attenuated these Eact-induced contractions. Pretreatment with Eact alone augmented the maximum acetylcholine contraction. Pretreatment of A/J mice in vivo with nebulized Eact caused an augmentation of methacholine-induced increases in airway resistance measured by the forced oscillatory technique (flexiVent). Pretreatment with the TMEM16A antagonist benzbromarone significantly attenuated methacholine-induced increases in airway resistance. In in vitro cellular studies, TMEM16A was found to be expressed more abundantly in ASM compared with epithelial cells in culture (8-fold higher in ASM). Eact caused an increase in intracellular calcium in human ASM cells that was completely attenuated by pretreatment with benzbromarone. Eact acutely depolarized the plasma membrane potential of ASM cells, which was attenuated by benzbromarone or nifedipine. The TMEM16A agonist Eact modulates ASM contraction in both ex vivo and in vivo models, suggesting that agonism of TMEM16A may lead to clinically relevant bronchospasm.
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Affiliation(s)
| | - Aisha S Kuforiji
- Department of Anesthesiology, Columbia University, New York, New York
| | - Gene T Yocum
- Department of Anesthesiology, Columbia University, New York, New York
| | - Yi Zhang
- Department of Anesthesiology, Columbia University, New York, New York
| | - Dingbang Xu
- Department of Anesthesiology, Columbia University, New York, New York
| | - George Gallos
- Department of Anesthesiology, Columbia University, New York, New York
| | - Charles W Emala
- Department of Anesthesiology, Columbia University, New York, New York
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Abstract
A spectrum of intrapulmonary airway diseases, for example, cigarette smoke-induced bronchitis, cystic fibrosis, primary ciliary dyskinesia, and non-cystic fibrosis bronchiectasis, can be categorized as "mucoobstructive" airway diseases. A common theme for these diseases appears to be the failure to properly regulate mucus concentration, producing mucus hyperconcentration that slows mucus transport and, importantly, generates plaque/plug adhesion to airway surfaces. These mucus plaques/plugs generate long diffusion distances for oxygen, producing hypoxic niches within adherent airway mucus and subjacent epithelia. Data suggest that concentrated mucus plaques/plugs are proinflammatory, in part mediated by release of IL-1α from hypoxic cells. The infectious component of mucoobstructive diseases may be initiated by anaerobic bacteria that proliferate within the nutrient-rich hypoxic mucus environment. Anaerobes ultimately may condition mucus to provide the environment for a succession to classic airway pathogens, including Staphylococcus aureus, Haemophilus influenzae, and ultimately Pseudomonas aeruginosa. Novel therapies to treat mucoobstructive diseases focus on restoring mucus concentration. Strategies to rehydrate mucus range from the inhalation of osmotically active solutes, designed to draw water into airway surfaces, to strategies designed to manipulate the relative rates of sodium absorption versus chloride secretion to endogenously restore epithelial hydration. Similarly, strategies designed to reduce the mucin burden in the airways, either by reducing mucin production/secretion or by clearing accumulated mucus (e.g., reducing agents), are under development. Thus, the new insights into a unifying process, that is, mucus hyperconcentration, that drives a significant component of the pathogenesis of mucoobstructive diseases promise multiple new therapeutic strategies to aid patients with this syndrome.
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Simões FB, Quaresma MC, Clarke LA, Silva IA, Pankonien I, Railean V, Kmit A, Amaral MD. TMEM16A chloride channel does not drive mucus production. Life Sci Alliance 2019; 2:2/6/e201900462. [PMID: 31732694 PMCID: PMC6859295 DOI: 10.26508/lsa.201900462] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/29/2019] [Accepted: 11/06/2019] [Indexed: 01/07/2023] Open
Abstract
Despite being essential for airway hydration, TMEM16A is not required for mucus (MUC5AC) production. Cell proliferation is the main driver for TMEM16A up-regulation during inflammation. Airway mucus obstruction is the main cause of morbidity in cystic fibrosis, a disease caused by mutations in the CFTR Cl− channel. Activation of non-CFTR Cl− channels such as TMEM16A can likely compensate for defective CFTR. However, TMEM16A was recently described as a key driver in mucus production/secretion. Here, we have examined whether indeed there is a causal relationship between TMEM16A and MUC5AC production, the main component of respiratory mucus. Our data show that TMEM16A and MUC5AC are inversely correlated during differentiation of human airway cells. Furthermore, we show for the first time that the IL-4–induced TMEM16A up-regulation is proliferation-dependent, which is supported by the correlation found between TMEM16A and Ki-67 proliferation marker during wound healing. Consistently, the notch signaling activator DLL4 increases MUC5AC levels without inducing changes neither in TMEM16A nor in Ki-67 expression. Moreover, TMEM16A inhibition decreased airway surface liquid height. Altogether, our findings demonstrate that up-regulation of TMEM16A and MUC5AC is only circumstantial under cell proliferation, but with no causal relationship between them. Thus, although essential for airway hydration, TMEM16A is not required for MUC5AC production.
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Affiliation(s)
- Filipa B Simões
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Margarida C Quaresma
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Luka A Clarke
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Iris Al Silva
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Ines Pankonien
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Violeta Railean
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Arthur Kmit
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Lisboa, Portugal
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Li H, Valkenier H, Thorne AG, Dias CM, Cooper JA, Kieffer M, Busschaert N, Gale PA, Sheppard DN, Davis AP. Anion carriers as potential treatments for cystic fibrosis: transport in cystic fibrosis cells, and additivity to channel-targeting drugs. Chem Sci 2019; 10:9663-9672. [PMID: 32055336 PMCID: PMC6984391 DOI: 10.1039/c9sc04242c] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/09/2019] [Indexed: 12/12/2022] Open
Abstract
Defective anion transport is a hallmark of the genetic disease cystic fibrosis (CF). One approach to restore anion transport to CF cells utilises alternative pathways for transmembrane anion transport, including artificial anion carriers (anionophores). Here, we screened 22 anionophores for biological activity using fluorescence emission from the halide-sensitive yellow fluorescent protein. Three compounds possessed anion transport activity similar to or greater than that of a bis-(p-nitrophenyl)ureidodecalin previously shown to have promising biological activity. Anion transport by these anionophores was concentration-dependent and persistent. All four anionophores mediated anion transport in CF cells, and their activity was additive to rescue of the predominant disease-causing variant F508del-CFTR using the clinically-licensed drugs lumacaftor and ivacaftor. Toxicity was variable but minimal at the lower end. The results provide further evidence that anionophores, by themselves or together with other treatments that restore anion transport, offer a potential therapeutic strategy for CF.
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Affiliation(s)
- Hongyu Li
- School of Physiology , Pharmacology and Neuroscience , University of Bristol , Biomedical Sciences Building, University Walk , Bristol BS8 1TD , UK .
| | - Hennie Valkenier
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Abigail G Thorne
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Christopher M Dias
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - James A Cooper
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Marion Kieffer
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | | | - Philip A Gale
- Chemistry , University of Southampton , Southampton SO17 1BJ , UK .
| | - David N Sheppard
- School of Physiology , Pharmacology and Neuroscience , University of Bristol , Biomedical Sciences Building, University Walk , Bristol BS8 1TD , UK .
| | - Anthony P Davis
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
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Abstract
Cl- is the major extracellular (Cl-out) and intracellular (Cl-in) anion whose concentration is actively regulated by multiple transporters. These transporters generate Cl- gradients across the plasma membrane and between the cytoplasm and intracellular organelles. [Cl-]in changes rapidly in response to cell stimulation and influences many physiological functions, as well as cellular and systemic homeostasis. However, less appreciated is the signaling function of Cl-. Cl- interacts with multiple proteins to directly modify their activity. This review highlights the signaling function of Cl- and argues that Cl- is a bona fide signaling ion, a function deserving extensive exploration.
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Affiliation(s)
- Benjamin P Lüscher
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Laura Vachel
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Ehud Ohana
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
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35
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Alternative chloride transport pathways as pharmacological targets for the treatment of cystic fibrosis. J Cyst Fibros 2019; 19 Suppl 1:S37-S41. [PMID: 31662238 DOI: 10.1016/j.jcf.2019.10.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/27/2019] [Accepted: 10/18/2019] [Indexed: 01/06/2023]
Abstract
Cystic fibrosis is a hereditary disease that originates from mutations in the epithelial chloride channel CFTR. Whereas established therapies for the treatment of cystic fibrosis target CFTR to repair its function, alternative therapeutic strategies aim for the restoration of chloride transport by the activation of other chloride transport proteins such as TMEM16A or SLC26A9 or by the application of synthetic anionophores. TMEM16A is an anion-selective channel that is activated by the binding of Ca2+ from the cytoplasm. Pharmacological efforts aim for the increase of its open probability at resting Ca2+ concentrations. SLC26 is an uncoupled chloride transporter, which shuttles chloride across the membrane by an alternate-access mechanism. Its activation requires its mobilization from intracellular stores. Finally, anionophores are small synthetic molecules that bind chloride to form lipid-soluble complexes, which shuttle the anion across the membrane. All three approaches are currently pursued and have provided promising initial results.
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36
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Zhu JS, Lu JY, Tan JA, Rivera AA, Phuan PW, Shatskikh ME, Son JH, Haggie PM, Verkman AS, Kurth MJ. Synthesis and evaluation of tetrahydropyrazolopyridine inhibitors of anion exchange protein SLC26A4 (pendrin). Bioorg Med Chem Lett 2019; 29:2119-2123. [PMID: 31281021 DOI: 10.1016/j.bmcl.2019.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/29/2019] [Accepted: 07/01/2019] [Indexed: 01/03/2023]
Abstract
Pendrin is a transmembrane chloride/anion antiporter that is strongly upregulated in the airways in rhinoviral infection, asthma, cystic fibrosis and chronic rhinosinusitis. Based on its role in the regulation of airway surface liquid depth, pendrin inhibitors have potential indications for treatment of inflammatory airways diseases. Here, a completely regioselective route to tetrahydro-pyrazolopyridine pendrin inhibitors based on 1,3-diketone and substituted hydrazine condensation was been developed. Structure-activity relationships at the tetrahydropyridyl nitrogen were investigated using a focused library, establishing the privileged nature of N-phenyl ureas and improving inhibitor potency by greater than 2-fold.
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Affiliation(s)
- Jie S Zhu
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Julia Y Lu
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Joseph-Anthony Tan
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Amber A Rivera
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Puay-Wah Phuan
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Marina E Shatskikh
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Jung-Ho Son
- Department of Chemistry, University of California, Davis, CA 95616, United States
| | - Peter M Haggie
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Alan S Verkman
- Departments of Medicine & Physiology, University of California, San Francisco, CA 94143, United States
| | - Mark J Kurth
- Department of Chemistry, University of California, Davis, CA 95616, United States.
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Hanrahan JW, Sato Y, Carlile GW, Jansen G, Young JC, Thomas DY. Cystic Fibrosis: Proteostatic correctors of CFTR trafficking and alternative therapeutic targets. Expert Opin Ther Targets 2019; 23:711-724. [PMID: 31169041 DOI: 10.1080/14728222.2019.1628948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Introduction: Cystic fibrosis (CF) is the most frequent lethal orphan disease and is caused by mutations in the CFTR gene. The most frequent mutation F508del-CFTR affects multiple organs; infections and subsequent infections and complications in the lung lead to death. Areas covered: This review focuses on new targets and mechanisms that are attracting interest for the development of CF therapies. The F508del-CFTR protein is retained in the endoplasmic reticulum (ER) but has some function if it can traffic to the plasma membrane. Cell-based assays have been used to screen chemical libraries for small molecule correctors that restore its trafficking. Pharmacological chaperones are correctors that bind directly to the F508del-CFTR mutant and promote its folding and trafficking. Other correctors fall into a heterogeneous class of proteostasis modulators that act indirectly by altering cellular homeostasis. Expert opinion: Pharmacological chaperones have so far been the most successful correctors of F508del-CFTR trafficking, but their level of correction means that more than one corrector is required. Proteostasis modulators have low levels of correction but hold promise because some can correct several different CFTR mutations. Identification of their cellular targets and the potential for development may lead to new therapies for CF.
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Affiliation(s)
- John W Hanrahan
- a Department of Physiology , McGill University , Montréal , QC , Canada.,c Research Institute of the McGill University Health Centre , McGill University , Montréal , QC , Canada
| | - Yukiko Sato
- a Department of Physiology , McGill University , Montréal , QC , Canada.,b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada
| | - Graeme W Carlile
- b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada.,d Department of Biochemistry , McGill University , Montréal , QC , Canada
| | - Gregor Jansen
- d Department of Biochemistry , McGill University , Montréal , QC , Canada
| | - Jason C Young
- b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada.,d Department of Biochemistry , McGill University , Montréal , QC , Canada
| | - David Y Thomas
- b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada.,d Department of Biochemistry , McGill University , Montréal , QC , Canada.,e Department of Human Genetics , McGill University , Montréal , QC , Canada
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38
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Fiore M, Cossu C, Capurro V, Picco C, Ludovico A, Mielczarek M, Carreira-Barral I, Caci E, Baroni D, Quesada R, Moran O. Small molecule-facilitated anion transporters in cells for a novel therapeutic approach to cystic fibrosis. Br J Pharmacol 2019; 176:1764-1779. [PMID: 30825185 DOI: 10.1111/bph.14649] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/05/2019] [Accepted: 02/08/2019] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE Cystic fibrosis (CF) is a lethal autosomal recessive genetic disease that originates from the defective function of the CF transmembrane conductance regulator (CFTR) protein, a cAMP-dependent anion channel involved in fluid transport across epithelium. Because small synthetic transmembrane anion transporters (anionophores) can replace the biological anion transport mechanisms, independent of genetic mutations in the CFTR, such anionophores are candidates as new potential treatments for CF. EXPERIMENTAL APPROACH In order to assess their effects on cell physiology, we have analysed the transport properties of five anionophore compounds, three prodigiosines and two tambjamines. Chloride efflux was measured in large uni-lamellar vesicles and in HEK293 cells with chloride-sensitive electrodes. Iodide influx was evaluated in FRT cells transfected with iodide-sensitive YFP. Transport of bicarbonate was assessed by changes of pH after a NH4 + pre-pulse using the BCECF fluorescent probe. Assays were also carried out in FRT cells permanently transfected with wild type and mutant human CFTR. KEY RESULTS All studied compounds are capable of transporting halides and bicarbonate across the cell membrane, with a higher transport capacity at acidic pH. Interestingly, the presence of these anionophores did not interfere with the activation of CFTR and did not modify the action of lumacaftor (a CFTR corrector) or ivacaftor (a CFTR potentiator). CONCLUSION AND IMPLICATIONS These anionophores, at low concentrations, transported chloride and bicarbonate across cell membranes, without affecting CFTR function. They therefore provide promising starting points for the development of novel treatments for CF.
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Affiliation(s)
| | | | - Valeria Capurro
- U.O.C. Genetica Medica, Istituto Giannina Gaslini, Genova, Italy
| | | | | | - Marcin Mielczarek
- Departamento de Química, Facultad de Ciencias, Universidad de Burgos, Burgos, Spain
| | | | - Emanuela Caci
- U.O.C. Genetica Medica, Istituto Giannina Gaslini, Genova, Italy
| | | | - Roberto Quesada
- Departamento de Química, Facultad de Ciencias, Universidad de Burgos, Burgos, Spain
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Khan MA, Ali ZS, Sweezey N, Grasemann H, Palaniyar N. Progression of Cystic Fibrosis Lung Disease from Childhood to Adulthood: Neutrophils, Neutrophil Extracellular Trap (NET) Formation, and NET Degradation. Genes (Basel) 2019; 10:genes10030183. [PMID: 30813645 PMCID: PMC6471578 DOI: 10.3390/genes10030183] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 02/11/2019] [Indexed: 12/11/2022] Open
Abstract
Genetic defects in cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene cause CF. Infants with CFTR mutations show a peribronchial neutrophil infiltration prior to the establishment of infection in their lung. The inflammatory response progressively increases in children that include both upper and lower airways. Infectious and inflammatory response leads to an increase in mucus viscosity and mucus plugging of small and medium-size bronchioles. Eventually, neutrophils chronically infiltrate the airways with biofilm or chronic bacterial infection. Perpetual infection and airway inflammation destroy the lungs, which leads to increased morbidity and eventual mortality in most of the patients with CF. Studies have now established that neutrophil cytotoxins, extracellular DNA, and neutrophil extracellular traps (NETs) are associated with increased mucus clogging and lung injury in CF. In addition to opportunistic pathogens, various aspects of the CF airway milieux (e.g., airway pH, salt concentration, and neutrophil phenotypes) influence the NETotic capacity of neutrophils. CF airway milieu may promote the survival of neutrophils and eventual pro-inflammatory aberrant NETosis, rather than the anti-inflammatory apoptotic death in these cells. Degrading NETs helps to manage CF airway disease; since DNAse treatment release cytotoxins from the NETs, further improvements are needed to degrade NETs with maximal positive effects. Neutrophil-T cell interactions may be important in regulating viral infection-mediated pulmonary exacerbations in patients with bacterial infections. Therefore, clarifying the role of neutrophils and NETs in CF lung disease and identifying therapies that preserve the positive effects of neutrophils, while reducing the detrimental effects of NETs and cytotoxic components, are essential in achieving innovative therapeutic advances.
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Affiliation(s)
- Meraj A Khan
- Translational Medicine, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
| | - Zubair Sabz Ali
- Translational Medicine, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
| | - Neil Sweezey
- Translational Medicine, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
- Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1X8, Canada.
- Division of Respiratory Medicine, Department of Paediatrics, The Hospital for Sick Children, and University of Toronto, Toronto, ON M5G 1X8, Canada.
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1X8, Canada.
| | - Hartmut Grasemann
- Translational Medicine, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
- Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1X8, Canada.
- Division of Respiratory Medicine, Department of Paediatrics, The Hospital for Sick Children, and University of Toronto, Toronto, ON M5G 1X8, Canada.
| | - Nades Palaniyar
- Translational Medicine, Peter Gilgan Center for Research and Learning, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
- Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1X8, Canada.
- Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1X8, Canada.
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Kunzelmann K, Ousingsawat J, Cabrita I, Doušová T, Bähr A, Janda M, Schreiber R, Benedetto R. TMEM16A in Cystic Fibrosis: Activating or Inhibiting? Front Pharmacol 2019; 10:3. [PMID: 30761000 PMCID: PMC6362895 DOI: 10.3389/fphar.2019.00003] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/04/2019] [Indexed: 12/26/2022] Open
Abstract
The inflammatory airway disease cystic fibrosis (CF) is characterized by airway obstruction due to mucus hypersecretion, airway plugging, and bronchoconstriction. The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is dysfunctional in CF, leading to defects in epithelial transport. Although CF pathogenesis is still disputed, activation of alternative Cl- channels is assumed to improve lung function in CF. Two suitable non-CFTR Cl- channels are present in the airway epithelium, the Ca2+ activated channel TMEM16A and SLC26A9. Activation of these channels is thought to be feasible to improve hydration of the airway mucus and to increase mucociliary clearance. Interestingly, both channels are upregulated during inflammatory lung disease. They are assumed to support fluid secretion, necessary to hydrate excess mucus and to maintain mucus clearance. During inflammation, however, TMEM16A is upregulated particularly in mucus producing cells, with only little expression in ciliated cells. Recently it was shown that knockout of TMEM16A in ciliated cells strongly compromises Cl- conductance and attenuated mucus secretion, but does not lead to a CF-like lung disease and airway plugging. Along this line, activation of TMEM16A by denufosol, a stable purinergic ligand, failed to demonstrate any benefit to CF patients in earlier studies. It rather induced adverse effects such as cough. A number of studies suggest that TMEM16A is essential for mucus secretion and possibly also for mucus production. Evidence is now provided for a crucial role of TMEM16A in fusion of mucus-filled granules with the apical plasma membrane and cellular exocytosis. This is probably due to local Ca2+ signals facilitated by TMEM16A. Taken together, TMEM16A supports fluid secretion by ciliated airway epithelial cells, but also maintains excessive mucus secretion during inflammatory airway disease. Because TMEM16A also supports airway smooth muscle contraction, inhibition rather than activation of TMEM16A might be the appropriate treatment for CF lung disease, asthma and COPD. As a number of FDA-approved and well-tolerated drugs have been shown to inhibit TMEM16A, evaluation in clinical trials appears timely.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | | | - Inês Cabrita
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Tereza Doušová
- Department of Pediatrics, Second Faculty of Medicine, University Hospital Motol, Charles University in Prague, Prague, Czechia
| | - Andrea Bähr
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
- Innere Medizin I, Klinikum Rechts der Isar der TU München, München, Germany
| | - Melanie Janda
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Roberta Benedetto
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
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41
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Shei RJ, Peabody JE, Kaza N, Rowe SM. The epithelial sodium channel (ENaC) as a therapeutic target for cystic fibrosis. Curr Opin Pharmacol 2018; 43:152-165. [PMID: 30340955 PMCID: PMC6294660 DOI: 10.1016/j.coph.2018.09.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 09/11/2018] [Indexed: 01/28/2023]
Abstract
Cystic fibrosis (CF) is a monogenic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR dysfunction is characterized by abnormal mucociliary transport due to a dehydrated airway surface liquid (ASL) and hyperviscous mucus, among other pathologies of host defense. ASL depletion is caused by the absence of CFTR mediated chloride secretion along with continued activity of the epithelial sodium channel (ENaC) activity, which can also be affected by CFTR mediated anion conductance. Therefore, ENaC has been proposed as a therapeutic target to ameliorate ASL dehydration and improve mucus transport. Inhibition of ENaC has been shown to restore ASL hydration and enhance mucociliary transport in induced models of CF lung disease. To date, no therapy inhibiting ENaC has successfully translated to clinical efficacy, in part due to concerns regarding off-target effects, systemic exposure, durability of effect, and adverse effects. Recent efforts have been made to develop novel, rationally designed therapeutics to produce-specific, long-lasting inhibition of ENaC activity in the airways while simultaneously minimizing off target fluid transport effects, systemic exposure and side effects. Such approaches comprise next-generation small molecule direct inhibitors, indirect channel-activating protease inhibitors, synthetic peptide analogs, and oligonucleotide-based therapies. These novel therapeutics represent an exciting step forward in the development of ENaC-directed therapies for CF.
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Affiliation(s)
- Ren-Jay Shei
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jacelyn E Peabody
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; Medical Scientist (MD/PhD) Training Program, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Niroop Kaza
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA.
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42
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Lam AK, Dutzler R. Calcium-dependent electrostatic control of anion access to the pore of the calcium-activated chloride channel TMEM16A. eLife 2018; 7:39122. [PMID: 30311910 PMCID: PMC6195346 DOI: 10.7554/elife.39122] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/11/2018] [Indexed: 12/14/2022] Open
Abstract
TMEM16A is a ligand-gated anion channel that is activated by intracellular Ca2+. This channel comprises two independent pores and closely apposed Ca2+ binding sites that are contained within each subunit of a homodimeric protein. Previously we characterized the influence of positively charged pore-lining residues on anion conduction (Paulino et al., 2017a). Here, we demonstrate the electrostatic control of permeation by the bound calcium ions in mouse TMEM16A using electrophysiology and Poisson-Boltzmann calculations. The currents of constitutively active mutants lose their outward rectification as a function of Ca2+ concentration due to the alleviation of energy barriers for anion conduction. This phenomenon originates from Coulombic interactions between the bound Ca2+ and permeating anions and thus demonstrates that an electrostatic gate imposed by the vacant binding site present in the sterically open pore, is released by Ca2+ binding to enable an otherwise sub-conductive pore to conduct with full capacity.
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Affiliation(s)
- Andy Km Lam
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
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43
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Balázs A, Mall MA. Role of the SLC26A9 Chloride Channel as Disease Modifier and Potential Therapeutic Target in Cystic Fibrosis. Front Pharmacol 2018; 9:1112. [PMID: 30327603 PMCID: PMC6174851 DOI: 10.3389/fphar.2018.01112] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/10/2018] [Indexed: 12/13/2022] Open
Abstract
The solute carrier family 26, member 9 (SLC26A9) is an epithelial chloride channel that is expressed in several organs affected in patients with cystic fibrosis (CF) including the lungs, the pancreas, and the intestine. Emerging evidence suggests SLC26A9 as a modulator of wild-type and mutant CFTR function, and as a potential alternative target to circumvent the basic ion transport defect caused by deficient CFTR-mediated chloride transport in CF. In this review, we summarize in vitro studies that revealed multifaceted molecular and functional interactions between SLC26A9 and CFTR that may be implicated in normal transepithelial chloride secretion in health, as well as impaired chloride/fluid transport in CF. Further, we focus on recent genetic association studies and investigations utilizing genetically modified mouse models that identified SLC26A9 as a disease modifier and supported an important role of this alternative chloride channel in the pathophysiology of several organ manifestations in CF, as well as other chronic lung diseases such as asthma and non-CF bronchiectasis. Collectively, these findings and the overlapping endogenous expression with CFTR suggest SLC26A9 an attractive novel therapeutic target that may be exploited to restore epithelial chloride secretion in patients with CF irrespective of their CFTR genotype. In addition, pharmacological activation of SLC26A9 may help to augment the effect of CFTR modulator therapies in patients with CF carrying responsive mutations such as the most common disease-causing mutation F508del-CFTR. However, future research and development including the identification of compounds that activate SLC26A9-mediated chloride transport are needed to explore this alternative chloride channel as a therapeutic target in CF and potentially other muco-obstructive lung diseases.
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Affiliation(s)
- Anita Balázs
- Department of Pediatric Pulmonology, Immunology and Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany.,German Center for Lung Research, Giessen, Germany
| | - Marcus A Mall
- Department of Pediatric Pulmonology, Immunology and Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany.,German Center for Lung Research, Giessen, Germany
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44
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Philippe R, Urbach V. Specialized Pro-Resolving Lipid Mediators in Cystic Fibrosis. Int J Mol Sci 2018; 19:ijms19102865. [PMID: 30241412 PMCID: PMC6213393 DOI: 10.3390/ijms19102865] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/14/2018] [Accepted: 09/15/2018] [Indexed: 12/22/2022] Open
Abstract
In cystic fibrosis (CF), impaired airway surface hydration (ASL) and mucociliary clearance that promote chronic bacterial colonization, persistent inflammation, and progressive structural damage to the airway wall architecture are typically explained by ion transport abnormalities related to the mutation of the gene coding for the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. However, the progressive and unrelenting inflammation of the CF airway begins early in life, becomes persistent, and is excessive relative to the bacterial burden. Intrinsic abnormalities of the inflammatory response in cystic fibrosis have been suggested but the mechanisms involved remain poorly understood. This review aims to give an overview of the recent advances in the understanding of the defective resolution of inflammation in CF including the abnormal production of specialized pro-resolving lipid mediators (lipoxin and resolvin) and their impact on the pathogenesis of the CF airway disease.
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Affiliation(s)
- Réginald Philippe
- INSERM, U1151, Institut Necker Enfants Malades, 75993 Paris, France.
| | - Valerie Urbach
- INSERM, U1151, Institut Necker Enfants Malades, 75993 Paris, France.
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45
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Liu X, Li T, Tuo B. Physiological and Pathophysiological Relevance of the Anion Transporter Slc26a9 in Multiple Organs. Front Physiol 2018; 9:1197. [PMID: 30233393 PMCID: PMC6127633 DOI: 10.3389/fphys.2018.01197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 08/08/2018] [Indexed: 02/05/2023] Open
Abstract
Transepithelial Cl- and HCO3- transport is crucial for the function of all epithelia, and HCO3- is a biological buffer that maintains acid-base homeostasis. In most epithelia, a series of Cl-/HCO3- exchangers and Cl- channels that mediate Cl- absorption and HCO3- secretion have been detected in the luminal and basolateral membranes. Slc26a9 belongs to the solute carrier 26 (Slc26) family of anion transporters expressed in the epithelia of multiple organs. This review summarizes the expression pattern and functional diversity of Slc26a9 in different systems based on all investigations performed thus far. Furthermore, the physical and functional interactions between Slc26a9 and cystic fibrosis transmembrane conductance regulator (CFTR) are discussed due to their overlapping expression pattern in multiple organs. Finally, we focus on the relationship between slc26a9 mutations and disease onset. An understanding of the physiological and pathophysiological relevance of Slc26a9 in multiple organs offers new possibilities for disease therapy.
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Affiliation(s)
- Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Taolang Li
- Department of Thyroid and Breast Surgery, Affiliated Hospital, Zunyi Medical University, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
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46
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Cossu C, Fiore M, Baroni D, Capurro V, Caci E, Garcia-Valverde M, Quesada R, Moran O. Anion-Transport Mechanism of a Triazole-Bearing Derivative of Prodigiosine: A Candidate for Cystic Fibrosis Therapy. Front Pharmacol 2018; 9:852. [PMID: 30131695 PMCID: PMC6090297 DOI: 10.3389/fphar.2018.00852] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/13/2018] [Indexed: 12/31/2022] Open
Abstract
Cystic fibrosis (CF) is a genetic lethal disease, originated from the defective function of the CFTR protein, a chloride and bicarbonate permeable transmembrane channel. CF mutations affect CFTR protein through a variety of molecular mechanisms which result in different functional defects. Current therapeutic approaches are targeted to specific groups of patients that share a common functional defect. We seek to develop an innovative therapeutic approach for the treatment of CF using anionophores, small molecules that facilitate the transmembrane transport of anions. We have characterized the anion transport mechanism of a synthetic molecule based on the structure of prodigiosine, a red pigment produced by bacteria. Anionophore-driven chloride efflux from large unilamellar vesicles is consistent with activity of an uniporter carrier that facilitates the transport of anions through lipid membranes down the electrochemical gradient. There are no evidences of transport coupling with protons. The selectivity sequence of the prodigiosin inspired EH160 ionophore is formate > acetate > nitrate > chloride > bicarbonate. Sulfate, phosphate, aspartate, isothionate, and gluconate are not significantly transported by these anionophores. Protonation at acidic pH is important for the transport capacity of the anionophore. This prodigiosin derived ionophore induces anion transport in living cells. Its low toxicity and capacity to transport chloride and bicarbonate, when applied at low concentration, constitute a promising starting point for the development of drug candidates for CF therapy.
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Affiliation(s)
- Claudia Cossu
- Istituto di Biofisica, Consiglio Nazionale Delle Ricerche, Genova, Italy
| | - Michele Fiore
- Istituto di Biofisica, Consiglio Nazionale Delle Ricerche, Genova, Italy
| | - Debora Baroni
- Istituto di Biofisica, Consiglio Nazionale Delle Ricerche, Genova, Italy
| | - Valeria Capurro
- U.O.C. Genetica Medica, Istituto Giannina Gaslini, Genova, Italy
| | - Emanuela Caci
- U.O.C. Genetica Medica, Istituto Giannina Gaslini, Genova, Italy
| | | | - Roberto Quesada
- Departamento de Química, Facultad de Ciencias, Universidad de Burgos, Burgos, Spain
| | - Oscar Moran
- Istituto di Biofisica, Consiglio Nazionale Delle Ricerche, Genova, Italy
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47
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Strug LJ, Stephenson AL, Panjwani N, Harris A. Recent advances in developing therapeutics for cystic fibrosis. Hum Mol Genet 2018; 27:R173-R186. [PMID: 30060192 PMCID: PMC6061831 DOI: 10.1093/hmg/ddy188] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 05/07/2018] [Accepted: 05/10/2018] [Indexed: 12/23/2022] Open
Abstract
Despite hope that a cure was imminent when the causative gene was cloned nearly 30 years ago, cystic fibrosis (CF [MIM: 219700]) remains a life-shortening disease affecting more than 70 000 individuals worldwide. However, within the last 6 years the Food and Drug Administration's approval of Ivacaftor, the first drug that corrects the defective cystic fibrosis transmembrane conductance regulator protein [CFTR (MIM: 602421)] in patients with the G551D mutation, marks a watershed in the development of novel therapeutics for this devastating disease. Here we review recent progress in diverse research areas, which all focus on curing CF at the genetic, biochemical or physiological level. In the near future it seems probable that development of mutation-specific therapies will be the focus, since it is unlikely that any one approach will be efficient in correcting the more than 2000 disease-associated variants. We discuss the new drugs and combinations of drugs that either enhance delivery of misfolded CFTR protein to the cell membrane, where it functions as an ion channel, or that activate channel opening. Next we consider approaches to correct the causative genetic lesion at the DNA or RNA level, through repressing stop mutations and nonsense-mediated decay, modulating splice mutations, fixing errors by gene editing or using novel routes to gene replacement. Finally, we explore how modifier genes, loci elsewhere in the genome that modify CF disease severity, may be used to restore a normal phenotype. Progress in all of these areas has been dramatic, generating enthusiasm that CF may soon become a broadly treatable disease.
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Affiliation(s)
- Lisa J Strug
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
- The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, ON, Canada
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Anne L Stephenson
- Department of Respirology, Adult Cystic Fibrosis Program, St. Michael’s Hospital, Toronto, ON, Canada
- Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada
| | - Naim Panjwani
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Ann Harris
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
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48
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Gentzsch M, Mall MA. Ion Channel Modulators in Cystic Fibrosis. Chest 2018; 154:383-393. [PMID: 29750923 PMCID: PMC6113631 DOI: 10.1016/j.chest.2018.04.036] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/15/2018] [Accepted: 04/27/2018] [Indexed: 02/06/2023] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and remains one of the most common life-shortening genetic diseases affecting the lung and other organs. CFTR functions as a cyclic adenosine monophosphate-dependent anion channel that transports chloride and bicarbonate across epithelial surfaces, and disruption of these ion transport processes plays a central role in the pathogenesis of CF. These findings provided the rationale for pharmacologic modulation of ion transport, either by targeting mutant CFTR or alternative ion channels that can compensate for CFTR dysfunction, as a promising therapeutic approach. High-throughput screening has supported the development of CFTR modulator compounds. CFTR correctors are designed to improve defective protein processing, trafficking, and cell surface expression, whereas potentiators increase the activity of mutant CFTR at the cell surface. The approval of the first potentiator ivacaftor for the treatment of patients with specific CFTR mutations and, more recently, the corrector lumacaftor in combination with ivacaftor for patients homozygous for the common F508del mutation, were major breakthroughs on the path to causal therapies for all patients with CF. The present review focuses on recent developments and remaining challenges of CFTR-directed therapies, as well as modulators of other ion channels such as alternative chloride channels and the epithelial sodium channel as additional targets in CF lung disease. We further discuss how patient-derived precision medicine models may aid the translation of emerging next-generation ion channel modulators from the laboratory to the clinic and tailor their use for optimal therapeutic benefits in individual patients with CF.
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Affiliation(s)
- Martina Gentzsch
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, NC; Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC
| | - Marcus A Mall
- Department of Pediatric Pulmonology, Immunology and Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Berlin, Germany; Berlin Institute of Health, Berlin, Germany; Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research, University of Heidelberg, Heidelberg, Germany.
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49
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Hahn A, Salomon JJ, Leitz D, Feigenbutz D, Korsch L, Lisewski I, Schrimpf K, Millar-Büchner P, Mall MA, Frings S, Möhrlen F. Expression and function of Anoctamin 1/TMEM16A calcium-activated chloride channels in airways of in vivo mouse models for cystic fibrosis research. Pflugers Arch 2018; 470:1335-1348. [DOI: 10.1007/s00424-018-2160-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/30/2018] [Accepted: 05/23/2018] [Indexed: 01/17/2023]
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50
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Bao X, Wu X, Berry SN, Howe ENW, Chang YT, Gale PA. Fluorescent squaramides as anion receptors and transmembrane anion transporters. Chem Commun (Camb) 2018; 54:1363-1366. [PMID: 29354832 DOI: 10.1039/c7cc08706c] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
A series of squaramide-based anion transporters functionalised with the 1,8-naphthalimide fluorophore has been developed for improved ionophoric activity and fluorescent imaging in cells.
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Affiliation(s)
- Xiaoping Bao
- Chemistry, University of Southampton, Southampton, SO17 1BJ, UK
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