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Danahay H, Lilley S, Adley K, Charlton H, Fox R, Gosling M. Niclosamide does not modulate airway epithelial function through blocking of the calcium activated chloride channel, TMEM16A. Front Pharmacol 2023; 14:1142342. [PMID: 36950016 PMCID: PMC10025480 DOI: 10.3389/fphar.2023.1142342] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 02/23/2023] [Indexed: 03/08/2023] Open
Abstract
Niclosamide and benzbromarone have been described as inhibitors of the calcium activated chloride channel, TMEM16A, and on this basis have been considered and tested as clinical candidates for the treatment of airway diseases. However, both compounds have previously demonstrated activity on a range of additional biological targets and it is unclear from the literature to what extent any activity on TMEM16A may contribute to efficacy in these models of airway disease. The aim of the present study was therefore to examine the pharmacology and selectivity of these clinical candidates together with a structurally unrelated TMEM16A blocker, Ani9, in a range of functional assays to better appreciate the putative role of TMEM16A in the regulation of both epithelial ion transport and the development of an airway epithelial mucus secretory phenoptype. Benzbromarone and Ani9 both attenuated recombinant TMEM16A activity in patch clamp studies, whereas in contrast, niclosamide induced a paradoxical potentiation of the TMEM16A-mediated current. Niclosamide and benzbromarone were also demonstrated to attenuate receptor-dependent increases in intracellular Ca2+ levels ([Ca2+]i) which likely contributed to their concomitant attenuation of the Ca2+-stimulated short-circuit current responses of FRT-TMEM16A and primary human bronchial epithelial (HBE) cells. In contrast, Ani9 attenuated the Ca2+-stimulated short-circuit current responses of both cell systems without influencing [Ca2+]i which supports a true channel blocking mechanism for this compound. Additional studies using HBE cells revealed effects of both niclosamide and benzbromarone on global ion transport processes (absorptive and secretory) as well as signs of toxicity (elevated LDH levels, loss of transepithelial resistance) that were not shared by Ani9. Ani9 also failed to influence the IL-13 induced differentiation of HBE towards a goblet cell rich, mucus hypersecreting epithelium, whereas niclosamide and benzbromarone attenuated numbers of both goblet and multiciliated cells, that would be consistent with cellular toxicity. Together these data challenge the description of niclosamide as a TMEM16A blocker and illustrate a range of off-target effects of both niclosamide and benzbromarone which may contribute to the reported activity in models of airway function.
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Affiliation(s)
- Henry Danahay
- Enterprise Therapeutics Ltd., Brighton, United Kingdom
- *Correspondence: Henry Danahay,
| | - Sarah Lilley
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Kathryn Adley
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Holly Charlton
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Roy Fox
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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Kountz TS, Biyasheva A, Schleimer RP, Prakriya M. Extracellular Nucleotides and Histamine Suppress TLR3- and RIG-I-Mediated Release of Antiviral IFNs from Human Airway Epithelial Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:2390-2402. [PMID: 35459743 PMCID: PMC9444327 DOI: 10.4049/jimmunol.2101085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 03/03/2022] [Indexed: 05/17/2023]
Abstract
Respiratory viruses stimulate the release of antiviral IFNs from the airway epithelium. Previous studies have shown that asthmatic patients show diminished release of type I and type III IFNs from bronchial epithelia. However, the mechanism of this suppression is not understood. In this study, we report that extracellular nucleotides and histamine, which are elevated in asthmatic airways, strongly inhibit release of type I and type III IFNs from human bronchial airway epithelial cells (AECs). Specifically, ATP, UTP, and histamine all inhibited the release of type I and type III IFNs from AECs induced by activation of TLR3, retinoic acid-inducible gene I (RIG-I), or cyclic GMP-AMP synthase-STING. This inhibition was at least partly mediated by Gq signaling through purinergic P2Y2 and H1 receptors, but it did not involve store-operated calcium entry. Pharmacological blockade of protein kinase C partially reversed inhibition of IFN production. Conversely, direct activation of protein kinase C with phorbol esters strongly inhibited TLR3- and RIG-I-mediated IFN production. Inhibition of type I and type III IFNs by ATP, UTP, histamine, and the proteinase-activated receptor 2 (PAR2) receptor agonist SLIGKV also occurred in differentiated AECs grown at an air-liquid interface, indicating that the suppression is conserved following mucociliary differentiation. Importantly, histamine and, more strikingly, ATP inhibited type I IFN release from human airway cells infected with live influenza A virus or rhinovirus 1B. These results reveal an important role for extracellular nucleotides and histamine in attenuating the induction of type I and III IFNs from AECs and help explain the molecular basis of the suppression of IFN responses in asthmatic patients.
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Affiliation(s)
- Timothy S Kountz
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL; and
| | - Assel Biyasheva
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Robert P Schleimer
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL; and
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
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Danahay HL, Lilley S, Fox R, Charlton H, Sabater J, Button B, McCarthy C, Collingwood SP, Gosling M. TMEM16A Potentiation: A Novel Therapeutic Approach for the Treatment of Cystic Fibrosis. Am J Respir Crit Care Med 2020; 201:946-954. [PMID: 31898911 PMCID: PMC7159426 DOI: 10.1164/rccm.201908-1641oc] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Rationale: Enhancing non–CFTR (cystic fibrosis transmembrane conductance regulator)-mediated anion secretion is an attractive therapeutic approach for the treatment of cystic fibrosis (CF) and other mucoobstructive diseases. Objectives: To determine the effects of TMEM16A potentiation on epithelial fluid secretion and mucociliary clearance. Methods: The effects of a novel low-molecular-weight TMEM16A potentiator (ETX001) were evaluated in human cell and animal models of airway epithelial function and mucus transport. Measurements and Main Results: Potentiating the activity of TMEM16A with ETX001 increased the Ca2+-activated Cl− channel activity and anion secretion in human bronchial epithelial (HBE) cells from patients with CF without impacting calcium signaling. ETX001 rapidly increased fluid secretion and airway surface liquid height in CF-HBE cells under both static conditions and conditions designed to mimic the shear stress associated with tidal breathing. In ovine models of mucus clearance (tracheal mucus velocity and mucociliary clearance), inhaled ETX001 was able to accelerate clearance both when CFTR function was reduced by administration of a pharmacological blocker and when CFTR was fully functional. Conclusions: Enhancing the activity of TMEM16A increases epithelial fluid secretion and enhances mucus clearance independent of CFTR function. TMEM16A potentiation is a novel approach for the treatment of patients with CF and non-CF mucoobstructive diseases.
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Affiliation(s)
| | - Sarah Lilley
- Sussex Drug Discovery Centre, University of Sussex, Brighton, United Kingdom
| | - Roy Fox
- Sussex Drug Discovery Centre, University of Sussex, Brighton, United Kingdom
| | - Holly Charlton
- Sussex Drug Discovery Centre, University of Sussex, Brighton, United Kingdom
| | - Juan Sabater
- Mount Sinai Medical Center of Florida, Miami, Florida; and
| | - Brian Button
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | | | | | - Martin Gosling
- Enterprise Therapeutics, Brighton, United Kingdom.,Sussex Drug Discovery Centre, University of Sussex, Brighton, United Kingdom
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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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Grygorczyk R, Boudreault F, Tan JJ, Ponomarchuk O, Sokabe M, Furuya K. Mechanosensitive ATP release in the lungs: New insights from real-time luminescence imaging studies. CURRENT TOPICS IN MEMBRANES 2019; 83:45-76. [PMID: 31196610 DOI: 10.1016/bs.ctm.2019.02.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Extracellular ATP and other nucleotides are important autocrine/paracrine mediators that stimulate purinergic receptors and regulate diverse processes in the normal lungs. They are also associated with pathogenesis of a number of respiratory diseases and clinical complications including acute respiratory distress syndrome and ventilator induced lung injury. Mechanical forces are major stimuli for cellular ATP release but precise mechanisms responsible for this release are still debated. The present review intends to provide the current state of knowledge of the mechanisms of ATP release in the lung. Putative pathways of the release, including the contribution of cell membrane injury and cell lysis are discussed addressing their strength, weaknesses and missing evidence that requires future study. We also provide an overview of the recent technical advances in studying cellular ATP release in vitro and ex vivo. Special attention is given to new insights into lung ATP release obtained with the real-time luminescence ATP imaging. This includes recent data on stretch-induced mechanosensitive ATP release in a model and primary cells of lung alveoli in vitro as well as inflation-induced ATP release in airspaces and pulmonary blood vessels of lungs, ex vivo.
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Affiliation(s)
- Ryszard Grygorczyk
- Department of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.
| | - Francis Boudreault
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Ju Jing Tan
- Department of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Olga Ponomarchuk
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada; Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University, Graduate School of Medicine, Nagoya, Japan
| | - Kishio Furuya
- Mechanobiology Laboratory, Nagoya University, Graduate School of Medicine, Nagoya, Japan
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Ivanova R, Benton DCH, Munye MM, Rangseesorranan S, Hart SL, Moss GWJ. A Nanosensor Toolbox for Rapid, Label-Free Measurement of Airway Surface Liquid and Epithelial Cell Function. ACS APPLIED MATERIALS & INTERFACES 2019; 11:8731-8739. [PMID: 30648848 DOI: 10.1021/acsami.8b14122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Ciliated lung epithelial cells and the airway surface liquid (ASL) comprise one of the body's most important protective systems. This system is finely tuned, and perturbations to ASL rheology, ASL depth, ASL pH, the transepithelial potential, and the cilia beat frequency are all associated with disease pathology. Further, these apparently distinct properties interact with each other in a complex manner. For example, changes in ASL rheology can result from altered mucin secretion, changes in ASL pH, or changes in ASL depth. Thus, one of the great challenges in trying to understand airway pathology is that the properties of the ASL/epithelial cell system need to be assessed near-simultaneously and without perturbing the sample. Here, we show that nanosensor probes mounted on a scanning ion conductance microscope make this possible for the first time, without any need for labeling. We also demonstrate that ASL from senescence-retarded human bronchial epithelial cells retains its native properties. Our results demonstrate that by using a nanosensor approach, it is possible to pursue faster, more accurate, more coherent, and more informative studies of ASL and airway epithelia in health and disease.
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Patel W, Moore PJ, Sassano MF, Lopes-Pacheco M, Aleksandrov AA, Amaral MD, Tarran R, Gray MA. Increases in cytosolic Ca 2+ induce dynamin- and calcineurin-dependent internalisation of CFTR. Cell Mol Life Sci 2019; 76:977-994. [PMID: 30547226 PMCID: PMC6394554 DOI: 10.1007/s00018-018-2989-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 11/28/2018] [Accepted: 12/04/2018] [Indexed: 12/12/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated, apical anion channel that regulates ion and fluid transport in many epithelia including the airways. We have previously shown that cigarette smoke (CS) exposure to airway epithelia causes a reduction in plasma membrane CFTR expression which correlated with a decrease in airway surface hydration. The effect of CS on CFTR was dependent on an increase in cytosolic Ca2+. However, the underlying mechanism for this Ca2+-dependent, internalisation of CFTR is unknown. To gain a better understanding of the effect of Ca2+ on CFTR, we performed whole cell current recordings to study the temporal effect of raising cytosolic Ca2+ on CFTR function. We show that an increase in cytosolic Ca2+ induced a time-dependent reduction in whole cell CFTR conductance, which was paralleled by a loss of cell surface CFTR expression, as measured by confocal and widefield fluorescence microscopy. The decrease in CFTR conductance and cell surface expression were both dynamin-dependent. Single channel reconstitution studies showed that raising cytosolic Ca2+ per se had no direct effect on CFTR. In fact, the loss of CFTR plasma membrane activity correlated with activation of calcineurin, a Ca2+-dependent phosphatase, suggesting that dephosphorylation of CFTR was linked to the loss of surface expression. In support of this, the calcineurin inhibitor, cyclosporin A, prevented the Ca2+-induced decrease in cell surface CFTR. These results provide a hitherto unrecognised role for cytosolic Ca2+ in modulating the residency of CFTR at the plasma membrane through a dynamin- and calcineurin-dependent mechanism.
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Affiliation(s)
- Waseema Patel
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
- Marsico Lung Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Patrick J Moore
- Marsico Lung Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - M Flori Sassano
- Marsico Lung Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Miquéias Lopes-Pacheco
- Faculty of Sciences, BioISI-Biosystems and Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Andrei A Aleksandrov
- Department of Biochemistry and Biophysics, Cystic Fibrosis Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Margarida D Amaral
- Faculty of Sciences, BioISI-Biosystems and Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Robert Tarran
- Marsico Lung Institute, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Cell Biology and Physiology, Cystic Fibrosis Research and Treatment Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael A Gray
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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8
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Abdullah LH, Coakley R, Webster MJ, Zhu Y, Tarran R, Radicioni G, Kesimer M, Boucher RC, Davis CW, Ribeiro CMP. Mucin Production and Hydration Responses to Mucopurulent Materials in Normal versus Cystic Fibrosis Airway Epithelia. Am J Respir Crit Care Med 2018; 197:481-491. [PMID: 29099608 PMCID: PMC5821906 DOI: 10.1164/rccm.201706-1139oc] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 11/03/2017] [Indexed: 01/01/2023] Open
Abstract
RATIONALE Cystic fibrosis (CF) airways disease produces a mucoobstructive lung phenotype characterized by airways mucus plugging, epithelial mucous cell metaplasia/hyperplasia, chronic infection, and inflammation. Simultaneous biochemical and functional in vivo studies of mucin synthesis and secretion from CF airways are not available. In vitro translational models may quantitate differential CF versus normal mucin and fluid secretory responses to infectious/inflammatory stimuli. OBJECTIVES We tested the hypothesis that CF airways exhibit defective epithelial fluid, but not mucin, secretory responses to bacterial/inflammatory host products. METHODS Well-differentiated primary human bronchial epithelial cultures were exposed to supernatant from mucopurulent material (SMM) from human CF airways as a test of bacterial/inflammatory host product stimulus. Human bronchial epithelia (HBE) with normal CF transmembrane conductance regulator function were compared with ΔF508/ΔF508 CF HBE. MEASUREMENTS AND MAIN RESULTS Acute (up to 60 min) SMM exposure promoted mucin secretion, but mucins were degraded by the proteolytic enzymes present in SMM. Chronic SMM exposure induced upregulation of mucin synthesis and storage and generated absolute increases in basal and stimulated mucin release in normal and CF cultures. These responses were similar in normal and CF cultures. In contrast, SMM produced a coordinated CF transmembrane conductance regulator-mediated Cl- secretory response in normal HBE, but not in CF HBE. The absence of the fluid secretory response in CF produced quantitatively more dehydrated mucus. CONCLUSIONS Our study reveals the interplay between regulation of mucin and fluid secretion rates in inflamed versus noninflamed conditions and why a hyperconcentrated mucus is produced in CF airways.
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Affiliation(s)
| | - Raymond Coakley
- Marsico Lung Institute and Cystic Fibrosis Research Center
- Department of Medicine
| | | | - Yunxiang Zhu
- Marsico Lung Institute and Cystic Fibrosis Research Center
| | - Robert Tarran
- Marsico Lung Institute and Cystic Fibrosis Research Center
- Department of Cell Biology and Physiology, and
| | | | - Mehmet Kesimer
- Marsico Lung Institute and Cystic Fibrosis Research Center
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Richard C. Boucher
- Marsico Lung Institute and Cystic Fibrosis Research Center
- Department of Medicine
| | - C. William Davis
- Marsico Lung Institute and Cystic Fibrosis Research Center
- Department of Cell Biology and Physiology, and
| | - Carla M. P. Ribeiro
- Marsico Lung Institute and Cystic Fibrosis Research Center
- Department of Medicine
- Department of Cell Biology and Physiology, and
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Gao DY, Zhang BL, Leung MCT, Au SCL, Wong PYD, Shum WWC. Coupling of TRPV6 and TMEM16A in epithelial principal cells of the rat epididymis. J Gen Physiol 2017; 148:161-82. [PMID: 27481714 PMCID: PMC4969799 DOI: 10.1085/jgp.201611626] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 07/13/2016] [Indexed: 01/31/2023] Open
Abstract
Principal cells regulate the ionic environment of the epididymal lumen via unknown mechanisms. Gao et al. use electrophysiological and pharmacological tools to characterize rat principal cells and reveal a TRPV6-mediated calcium conductance and TMEM16A-mediated calcium-activated chloride conductance. The epididymis establishes a congenial environment for sperm maturation and protection. Its fluid is acidic, and the calcium concentration is low and declines along the length of the epididymal tubule. However, our knowledge of ionic currents and mechanisms of calcium homeostasis in rat epididymal epithelial cells remains enigmatic. In this study, to better understand calcium regulation in the epididymis, we use the patch-clamp method to record from single rat cauda epididymal principal cells. We detect a constitutively active Ca2+ current with characteristics that match the epithelial calcium channel TRPV6. Electrophysiological and pharmacological data also reveal a constitutively active calcium-activated chloride conductance (CaCC). Removal of extracellular calcium attenuates not only the TRPV6-like conductance, but also the CaCC. Lanthanide block is time dependent such that the TRPV6-like component is inhibited first, followed by the CaCC. The putative CaCC blocker niflumic acid partially inhibits whole-cell currents, whereas La3+ almost abolishes whole-cell currents in principal cells. Membrane potential measurements reveal an interplay between La3+-sensitive ion channels and those that are sensitive to the specific TMEM16A inhibitor tannic acid. In vivo perfusion of the cauda epididymal tubule shows a substantial rate of Ca2+ reabsorption from the luminal side, which is dose-dependently suppressed by ruthenium red, a putative blocker of epithelial Ca2+ channels and CaCC. Finally, we discover messenger RNA for both TRPV6 and TMEM16A in the rat epididymis and show that their proteins colocalize in the apical membrane of principal cells. Collectively, these data provide evidence for a coupling mechanism between TRPV6 and TMEM16A in principal cells that may play an important role in the regulation of calcium homeostasis in the epididymis.
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Affiliation(s)
- Da Yuan Gao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Bao Li Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Matthew C T Leung
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Simon C L Au
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Patrick Y D Wong
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Winnie W C Shum
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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Baaske R, Richter M, Möller N, Ziesemer S, Eiffler I, Müller C, Hildebrandt JP. ATP Release from Human Airway Epithelial Cells Exposed to Staphylococcus aureus Alpha-Toxin. Toxins (Basel) 2016; 8:toxins8120365. [PMID: 27929417 PMCID: PMC5198559 DOI: 10.3390/toxins8120365] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 11/20/2022] Open
Abstract
Airway epithelial cells reduce cytosolic ATP content in response to treatment with S. aureus alpha-toxin (hemolysin A, Hla). This study was undertaken to investigate whether this is due to attenuated ATP generation or to release of ATP from the cytosol and extracellular ATP degradation by ecto-enzymes. Exposure of cells to rHla did result in mitochondrial calcium uptake and a moderate decline in mitochondrial membrane potential, indicating that ATP regeneration may have been attenuated. In addition, ATP may have left the cells through transmembrane pores formed by the toxin or through endogenous release channels (e.g., pannexins) activated by cellular stress imposed on the cells by toxin exposure. Exposure of cells to an alpha-toxin mutant (H35L), which attaches to the host cell membrane but does not form transmembrane pores, did not induce ATP release from the cells. The Hla-mediated ATP-release was completely blocked by IB201, a cyclodextrin-inhibitor of the alpha-toxin pore, but was not at all affected by inhibitors of pannexin channels. These results indicate that, while exposure of cells to rHla may somewhat reduce ATP production and cellular ATP content, a portion of the remaining ATP is released to the extracellular space and degraded by ecto-enzymes. The release of ATP from the cells may occur directly through the transmembrane pores formed by alpha-toxin.
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Affiliation(s)
- Romina Baaske
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
| | - Mandy Richter
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
| | - Nils Möller
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
| | - Sabine Ziesemer
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
| | - Ina Eiffler
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
| | - Christian Müller
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
| | - Jan-Peter Hildebrandt
- Animal Physiology and Biochemistry, Ernst Moritz Arndt-University, Felix Hausdorff-Strasse 1, B.10.06, D-17489 Greifswald, Germany.
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11
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Agbani EO, van den Bosch MTJ, Brown E, Williams CM, Mattheij NJA, Cosemans JMEM, Collins PW, Heemskerk JWM, Hers I, Poole AW. Coordinated Membrane Ballooning and Procoagulant Spreading in Human Platelets. Circulation 2015; 132:1414-24. [PMID: 26330411 DOI: 10.1161/circulationaha.114.015036] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 07/30/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Platelets are central to the process of hemostasis, rapidly aggregating at sites of blood vessel injury and acting as coagulation nidus sites. On interaction with the subendothelial matrix, platelets are transformed into balloonlike structures as part of the hemostatic response. It remains unclear, however, how and why platelets generate these structures. We set out to determine the physiological relevance and cellular and molecular mechanisms underlying platelet membrane ballooning. METHODS AND RESULTS Using 4-dimensional live-cell imaging and electron microscopy, we show that human platelets adherent to collagen are transformed into phosphatidylserine-exposing balloonlike structures with expansive macro/microvesiculate contact surfaces, by a process that we termed procoagulant spreading. We reveal that ballooning is mechanistically and structurally distinct from membrane blebbing and involves disruption to the platelet microtubule cytoskeleton and inflation through fluid entry. Unlike blebbing, procoagulant ballooning is irreversible and a consequence of Na(+), Cl(-), and water entry. Furthermore, membrane ballooning correlated with microparticle generation. Inhibition of Na(+), Cl(-), or water entry impaired ballooning, procoagulant spreading, and microparticle generation, and it also diminished local thrombin generation. Human Scott syndrome platelets, which lack expression of Ano-6, also showed a marked reduction in membrane ballooning, consistent with a role for chloride entry in the process. Finally, the blockade of water entry by acetazolamide attenuated ballooning in vitro and markedly suppressed thrombus formation in vivo in a mouse model of thrombosis. CONCLUSIONS Ballooning and procoagulant spreading of platelets are driven by fluid entry into the cells, and are important for the amplification of localized coagulation in thrombosis.
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Affiliation(s)
- Ejaife O Agbani
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.).
| | - Marion T J van den Bosch
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Ed Brown
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Christopher M Williams
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Nadine J A Mattheij
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Judith M E M Cosemans
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Peter W Collins
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Johan W M Heemskerk
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Ingeborg Hers
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.)
| | - Alastair W Poole
- From School of Physiology & Pharmacology, University of Bristol, United Kingdom (E.O.A., M.T.J.v.d.B., E.B., C.M.W., I.H., A.W.P.; Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, The Netherlands (N.J.A.M., J.M.E.M.C., J.W.M.H.); and Welsh Blood Service and Arthur Bloom Haemophilia Centre, School of Medicine, Cardiff University, United Kingdom (P.W.C.).
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12
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Lee H, Koh BH, Yamasaki E, George NE, Sanders KM, Koh SD. UTP activates small-conductance Ca2+-activated K+ channels in murine detrusor PDGFRα+ cells. Am J Physiol Renal Physiol 2015. [PMID: 26202222 DOI: 10.1152/ajprenal.00156.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Purines induce transient contraction and prolonged relaxation of detrusor muscles. Transient contraction is likely due to activation of inward currents in smooth muscle cells, and prolonged relaxation may be due to activation of small-conductance Ca(2+)-activated K(+) (SK) channels via P2Y1 receptors expressed by detrusor PDGF receptor (PDGFR)α(+) cells. We investigated whether other subtypes of P2Y receptors are involved in the activation of SK channels in PDGFRα(+) cells of detrusor muscles. Quantitative analysis of transcripts revealed that P2ry2, P2ry4, and P2ry14 are expressed in PDGFRα(+) cells of P2ry1-deficient/enhanced green fluorescent protein (P2ry1(-/-)/eGFP) mice at similar levels as in wild-type mice. UTP, a P2Y2/P2Y4 agonist, activated large outward currents in detrusor PDGFRα(+) cells. SK channel blockers and an inhibitor of phospholipase C completely abolished currents activated by UTP. In contrast, UTP activated nonselective cation currents in smooth muscle cells. Under current-clamp (current = 0), UTP induced significant hyperpolarization of PDGFRα(+) cells. MRS2500, a selective P2Y1 antagonist, did not affect UTP-activated outward currents in PDGFRα(+) cells from wild-type mice, and activation of outward currents by UTP was retained in P2ry1(-/-)/eGFP mice. As a negative control, we tested the effect of MRS2693, a selective P2Y6 agonist. This compound did not activate outward currents in PDGFRα(+) cells, and currents activated by UTP were unaffected by MRS2578, a selective P2Y6 antagonist. The nonselective P2Y receptor blocker suramin inhibited UTP-activated outward currents in PDGFRα(+) cells. Our data demonstrate that P2Y2 and/or P2Y4 receptors function, in addition to P2Y1 receptors, in activating SK currents in PDGFRα(+) cells and possibly in mediating purinergic relaxation responses in detrusor muscles.
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Affiliation(s)
- Haeyeong Lee
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Byoung H Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Evan Yamasaki
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Nikita E George
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
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13
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Sharp K, Crampin E, Sneyd J. A spatial model of fluid recycling in the airways of the lung. J Theor Biol 2015; 382:198-215. [PMID: 26169010 DOI: 10.1016/j.jtbi.2015.06.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 06/26/2015] [Accepted: 06/30/2015] [Indexed: 12/11/2022]
Abstract
The genetic disease cystic fibrosis (CF) is a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, and results in viscous mucus and impaired mucociliary clearance leading to chronic recurring pulmonary infections. Although extensive experimental research has been conducted over the last few decades, CF lung pathophysiology remains controversial. There are two competing explanations for the observed depletion of periciliary liquid (PCL) in CF lungs. The low volume hypothesis assumes fluid hyperabsorption through surface epithelia due to an over-active epithelial Na(+) channel (ENaC), and the low secretion hypothesis assumes inspissated mucins secreted from glands due to lack of serous fluid secreted from gland acini. We present a spatial mathematical model that reflects in vivo fluid recycling via submucosal gland (SMG) secretion, and absorption through surface epithelia. We then test the model in CF conditions by increasing ENaC open probability and decreasing SMG flux while simultaneously reducing CFTR open probability. Increasing ENaC activity only results in increased fluid absorption across surface epithelia, as seen in in vitro experiments. However, combining potential CF mechanisms results in markedly less fluid absorbed while providing the largest reduction in PCL volume, suggesting that a compromise in gland fluid secretion dominates over increased ENaC activity to decrease the amount of fluid transported transcellularly in CF lungs in vivo. Model results also indicate that a spatial model is necessary for an accurate calculation of total fluid transport, as the effects of spatial gradients can be severe, particularly in close proximity to the SMGs.
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Affiliation(s)
- Katie Sharp
- Department of Mathematics, University of Auckland, 23 Princes St, Auckland CBD, Auckland 1010, New Zealand.
| | - Edmund Crampin
- Department of Biomedical Engineering, Level 4, University of Melbourne, Parkville 3010, Victoria, Australia
| | - James Sneyd
- Department of Mathematics, University of Auckland, 23 Princes St, Auckland CBD, Auckland 1010, New Zealand
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14
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Sun H, Harris WT, Kortyka S, Kotha K, Ostmann AJ, Rezayat A, Sridharan A, Sanders Y, Naren AP, Clancy JP. Tgf-beta downregulation of distinct chloride channels in cystic fibrosis-affected epithelia. PLoS One 2014; 9:e106842. [PMID: 25268501 PMCID: PMC4182049 DOI: 10.1371/journal.pone.0106842] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 08/05/2014] [Indexed: 01/15/2023] Open
Abstract
Rationale The cystic fibrosis transmembrane conductance regulator (CFTR) and Calcium-activated Chloride Conductance (CaCC) each play critical roles in maintaining normal hydration of epithelial surfaces including the airways and colon. TGF-beta is a genetic modifier of cystic fibrosis (CF), but how it influences the CF phenotype is not understood. Objectives We tested the hypothesis that TGF-beta potently downregulates chloride-channel function and expression in two CF-affected epithelia (T84 colonocytes and primary human airway epithelia) compared with proteins known to be regulated by TGF-beta. Measurements and Main Results TGF-beta reduced CaCC and CFTR-dependent chloride currents in both epithelia accompanied by reduced levels of TMEM16A and CFTR protein and transcripts. TGF-beta treatment disrupted normal regulation of airway-surface liquid volume in polarized primary human airway epithelia, and reversed F508del CFTR correction produced by VX-809. TGF-beta effects on the expression and activity of TMEM16A, wtCFTR and corrected F508del CFTR were seen at 10-fold lower concentrations relative to TGF-beta effects on e-cadherin (epithelial marker) and vimentin (mesenchymal marker) expression. TGF-beta downregulation of TMEM16A and CFTR expression were partially reversed by Smad3 and p38 MAPK inhibition, respectively. Conclusions TGF-beta is sufficient to downregulate two critical chloride transporters in two CF-affected tissues that precedes expression changes of two distinct TGF-beta regulated proteins. Our results provide a plausible mechanism for CF-disease modification by TGF-beta through effects on CaCC.
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Affiliation(s)
- Hongtao Sun
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - William T. Harris
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Stephanie Kortyka
- University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Kavitha Kotha
- Department of Pediatrics, Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Alicia J. Ostmann
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Amir Rezayat
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Anusha Sridharan
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Yan Sanders
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Anjaparavanda P. Naren
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - John P. Clancy
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America
- * E-mail:
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15
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Umunakwe OC, Seegmiller AC. Abnormal n-6 fatty acid metabolism in cystic fibrosis is caused by activation of AMP-activated protein kinase. J Lipid Res 2014; 55:1489-97. [PMID: 24859760 DOI: 10.1194/jlr.m050369] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Indexed: 12/14/2022] Open
Abstract
Cystic fibrosis (CF) patients and model systems exhibit consistent abnormalities in PUFA metabolism, including increased metabolism of linoleate to arachidonate. Recent studies have connected these abnormalities to increased expression and activity of the Δ6- and Δ5-desaturase enzymes. However, the mechanism connecting these changes to the CF transmembrane conductance regulator (CFTR) mutations responsible for CF is unknown. This study tests the hypothesis that increased activity of AMP-activated protein kinase (AMPK), previously described in CF bronchial epithelial cells, causes these changes in fatty acid metabolism by driving desaturase expression. Using CF bronchial epithelial cell culture models, we confirm elevated activity of AMPK in CF cells and show that it is due to increased phosphorylation of AMPK by Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ). We also show that inhibition of AMPK or CaMKKβ reduces desaturase expression and reverses the metabolic alterations seen in CF cells. These results signify a novel AMPK-dependent mechanism linking the genetic defect in CF to alterations in PUFA metabolism.
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Affiliation(s)
- Obi C Umunakwe
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Adam C Seegmiller
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
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16
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Ruffin M, Voland M, Marie S, Bonora M, Blanchard E, Blouquit-Laye S, Naline E, Puyo P, Le Rouzic P, Guillot L, Corvol H, Clement A, Tabary O. Anoctamin 1 dysregulation alters bronchial epithelial repair in cystic fibrosis. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2340-51. [PMID: 24080196 DOI: 10.1016/j.bbadis.2013.09.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 08/30/2013] [Accepted: 09/19/2013] [Indexed: 01/08/2023]
Abstract
Cystic fibrosis (CF) airway epithelium is constantly subjected to injury events due to chronic infection and inflammation. Moreover, abnormalities in CF airway epithelium repair have been described and contribute to the lung function decline seen in CF patients. In the last past years, it has been proposed that anoctamin 1 (ANO1), a Ca(2+)-activated Cl(-) channel, might offset the CFTR deficiency but this protein has not been characterized in CF airways. Interestingly, recent evidence indicates a role for ANO1 in cell proliferation and tumor growth. Our aims were to study non-CF and CF bronchial epithelial repair and to determine whether ANO1 is involved in airway epithelial repair. Here, we showed, with human bronchial epithelial cell lines and primary cells, that both cell proliferation and migration during epithelial repair are delayed in CF compared to non-CF cells. We then demonstrated that ANO1 Cl(-) channel activity was significantly decreased in CF versus non-CF cells. To explain this decreased Cl(-) channel activity in CF context, we compared ANO1 expression in non-CF vs. CF bronchial epithelial cell lines and primary cells, in lung explants from wild-type vs. F508del mice and non-CF vs. CF patients. In all these models, ANO1 expression was markedly lower in CF compared to non-CF. Finally, we established that ANO1 inhibition or overexpression was associated respectively with decreases and increases in cell proliferation and migration. In summary, our study demonstrates involvement of ANO1 decreased activity and expression in abnormal CF airway epithelial repair and suggests that ANO1 correction may improve this process.
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Affiliation(s)
- Manon Ruffin
- Inserm, U938, 34 Rue Crozatier, 75012 Paris, France; UPMC, University of Paris 06, 4 Place Jussieu, 75005 Paris, France
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17
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Burnstock G, Brouns I, Adriaensen D, Timmermans JP. Purinergic signaling in the airways. Pharmacol Rev 2012; 64:834-68. [PMID: 22885703 DOI: 10.1124/pr.111.005389] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Evidence for a significant role and impact of purinergic signaling in normal and diseased airways is now beyond dispute. The present review intends to provide the current state of knowledge of the involvement of purinergic pathways in the upper and lower airways and lungs, thereby differentiating the involvement of different tissues, such as the epithelial lining, immune cells, airway smooth muscle, vasculature, peripheral and central innervation, and neuroendocrine system. In addition to the vast number of well illustrated functions for purinergic signaling in the healthy respiratory tract, increasing data pointing to enhanced levels of ATP and/or adenosine in airway secretions of patients with airway damage and respiratory diseases corroborates the emerging view that purines act as clinically important mediators resulting in either proinflammatory or protective responses. Purinergic signaling has been implicated in lung injury and in the pathogenesis of a wide range of respiratory disorders and diseases, including asthma, chronic obstructive pulmonary disease, inflammation, cystic fibrosis, lung cancer, and pulmonary hypertension. These ostensibly enigmatic actions are based on widely different mechanisms, which are influenced by the cellular microenvironment, but especially the subtypes of purine receptors involved and the activity of distinct members of the ectonucleotidase family, the latter being potential protein targets for therapeutic implementation.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Royal Free Campus, London, UK.
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18
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Erb L, Weisman GA. Coupling of P2Y receptors to G proteins and other signaling pathways. ACTA ACUST UNITED AC 2012; 1:789-803. [PMID: 25774333 DOI: 10.1002/wmts.62] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
P2Y receptors are G protein-coupled receptors (GPCRs) that are activated by adenine and uridine nucleotides and nucleotide sugars. There are eight subtypes of P2Y receptors (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14), which activate intracellular signaling cascades to regulate a variety of cellular processes, including proliferation, differentiation, phagocytosis, secretion, nociception, cell adhesion, and cell migration. These signaling cascades operate mainly by the sequential activation or deactivation of heterotrimeric and monomeric G proteins, phospholipases, adenylyl and guanylyl cyclases, protein kinases, and phosphodiesterases. In addition, there are numerous ion channels, cell adhesion molecules, and receptor tyrosine kinases that are modulated by P2Y receptors and operate to transmit an extracellular signal to an intracellular response.
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Affiliation(s)
- Laurie Erb
- Department of Biochemistry, Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Gary A Weisman
- Department of Biochemistry, Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
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19
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CHOLEWA JASONMICHAEL, PAOLONE VINCENTJ. Influence of Exercise on Airway Epithelia in Cystic Fibrosis. Med Sci Sports Exerc 2012; 44:1219-26. [DOI: 10.1249/mss.0b013e31824bd436] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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20
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Kunzelmann K, Tian Y, Martins JR, Faria D, Kongsuphol P, Ousingsawat J, Wolf L, Schreiber R. Airway epithelial cells--functional links between CFTR and anoctamin dependent Cl- secretion. Int J Biochem Cell Biol 2012; 44:1897-900. [PMID: 22710346 DOI: 10.1016/j.biocel.2012.06.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/02/2012] [Accepted: 06/11/2012] [Indexed: 11/29/2022]
Abstract
Airways consist of a heterogeneous population of cells, comprising ciliated cells, Clara cells and goblet cells. Electrolyte secretion by the airways is necessary to produce the airway surface liquid that allows for mucociliary clearance of the lungs. Secretion is driven by opening of Cl(-) selective ion channels in the apical membrane of airway epithelial cells, through either receptor mediated increase in intracellular cAMP or cytosolic Ca(2+). Traditionally cAMP-dependent and Ca(2+)-dependent secretory pathways are regarded as independent. However, this concept has been challenged recently. With identification of the Ca(2+) activated Cl(-) channel TMEM16A (anoctamin 1) and with detailed knowledge of the cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR), it has become possible to look more closely into this relationship.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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21
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Lipoxin A4 stimulates calcium-activated chloride currents and increases airway surface liquid height in normal and cystic fibrosis airway epithelia. PLoS One 2012; 7:e37746. [PMID: 22662206 PMCID: PMC3360607 DOI: 10.1371/journal.pone.0037746] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 04/24/2012] [Indexed: 01/08/2023] Open
Abstract
Cystic Fibrosis (CF) is a genetic disease characterised by a deficit in epithelial Cl− secretion which in the lung leads to airway dehydration and a reduced Airway Surface Liquid (ASL) height. The endogenous lipoxin LXA4 is a member of the newly identified eicosanoids playing a key role in ending the inflammatory process. Levels of LXA4 are reported to be decreased in the airways of patients with CF. We have previously shown that in normal human bronchial epithelial cells, LXA4 produced a rapid and transient increase in intracellular Ca2+. We have investigated, the effect of LXA4 on Cl− secretion and the functional consequences on ASL generation in bronchial epithelial cells obtained from CF and non-CF patient biopsies and in bronchial epithelial cell lines. We found that LXA4 stimulated a rapid intracellular Ca2+ increase in all of the different CF bronchial epithelial cells tested. In non-CF and CF bronchial epithelia, LXA4 stimulated whole-cell Cl− currents which were inhibited by NPPB (calcium-activated Cl− channel inhibitor), BAPTA-AM (chelator of intracellular Ca2+) but not by CFTRinh-172 (CFTR inhibitor). We found, using confocal imaging, that LXA4 increased the ASL height in non-CF and in CF airway bronchial epithelia. The LXA4 effect on ASL height was sensitive to bumetanide, an inhibitor of transepithelial Cl− secretion. The LXA4 stimulation of intracellular Ca2+, whole-cell Cl− currents, conductances and ASL height were inhibited by Boc-2, a specific antagonist of the ALX/FPR2 receptor. Our results provide, for the first time, evidence for a novel role of LXA4 in the stimulation of intracellular Ca2+ signalling leading to Ca2+-activated Cl− secretion and enhanced ASL height in non-CF and CF bronchial epithelia.
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22
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Paisley D, Gosling M, Danahay H. Regulation of airway mucosal hydration. Expert Rev Clin Pharmacol 2012; 3:361-9. [PMID: 22111616 DOI: 10.1586/ecp.10.19] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Ion channels control the hydration status of the airway epithelium through apical anion secretion and cation absorption, which is accompanied by osmotically obligated water. The key channels in this process are the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), which is principally responsible for Cl(-) secretion by airway epithelial cells, and the epithelial Na(+) channel (ENaC), which is responsible for the absorption of Na ions. In CF, defective CFTR-mediated Cl(-) secretion and an accompanying upregulation in ENaC-mediated Na absorption results in a reduction in airway surface liquid volume, leading to poorly hydrated mucus and impaired mucociliary clearance. Restoration of normal airway hydration by modulation of ion channel activity represents an important therapeutic strategy for CF. CFTR corrector and potentiator compounds are being developed with the aim of recovering normal Cl(-) secretion. Ca(2+)-activated Cl(-) channels (CaCCs) are expressed by the respiratory epithelia and are reported to be functionally upregulated in CF and offer a 'surrogate' pathway for Cl(-) secretion. TMEM16A has recently been described as a CaCC in the airway epithelium and, as such, represents an alternative target for restoring Cl(-) secretion in CF. An alternative therapeutic strategy for CF is to inhibit ENaC, thereby blocking excessive Na absorption. This can be achieved by direct blockade of ENaC or inhibition of the channel-activating proteases (CAPs), whose activity regulates ENaC function. This review will describe the regulation of airway mucosal hydration by ion channels and the efforts currently underway to restore normal mucosal hydration in disease patients by modulating the function of these channels.
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Affiliation(s)
- Derek Paisley
- Novartis Institutes for Biomedical Research, Wimblehurst Road, Horsham, West Sussex, UK
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23
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Martins JR, Kongsuphol P, Sammels E, Dahimène S, AlDehni F, Clarke LA, Schreiber R, de Smedt H, Amaral MD, Kunzelmann K. F508del-CFTR increases intracellular Ca2+ signaling that causes enhanced calcium-dependent Cl− conductance in cystic fibrosis. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1385-92. [DOI: 10.1016/j.bbadis.2011.08.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Revised: 08/09/2011] [Accepted: 08/23/2011] [Indexed: 10/17/2022]
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Ribeiro CMP. Measurements of intracellular calcium signals in polarized primary cultures of normal and cystic fibrosis human airway epithelia. Methods Mol Biol 2011; 742:113-26. [PMID: 21547729 DOI: 10.1007/978-1-61779-120-8_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The airways are continuously challenged by a variety of stimuli including bacteria, viruses, allergens, and inflammatory factors that act as agonists for G protein-coupled receptors (GPCR). Intracellular calcium (Ca(2+) (i)) mobilization in airway epithelia in response to extracellular stimuli regulates key airway innate defense functions, e.g., Ca(2+)-activated Cl(-) secretion, ciliary beating, mucin secretion, and inflammatory responses. Because Ca(2+) (i) mobilization in response to luminal stimuli is larger in CF vs. normal human airway epithelia, alterations in Ca(2+) (i) signals have been associated with the pathogenesis of CF airway disease. Hence, assessment of Ca(2+) (i) signaling has become an important area of CF research. This chapter will focus on measurements of cytoplasmic and mitochondrial Ca(2+) signals resulting from GPCR activation in polarized primary cultures of normal and CF human bronchial epithelia (HBE).
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Affiliation(s)
- Carla M P Ribeiro
- Department of Medicine, Cystic Fibrosis/Pulmonary Research and Treatment Center, The University of North Carolina, Chapel Hill, NC 27599-7248, USA.
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Novak I. Purinergic signalling in epithelial ion transport: regulation of secretion and absorption. Acta Physiol (Oxf) 2011; 202:501-22. [PMID: 21073662 DOI: 10.1111/j.1748-1716.2010.02225.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intracellular ATP, the energy source for many reactions, is crucial for the activity of plasma membrane pumps and, thus, for the maintenance of transmembrane ion gradients. Nevertheless, ATP and other nucleotides/nucleosides are also extracellular molecules that regulate diverse cellular functions, including ion transport. In this review, I will first introduce the main components of the extracellular ATP signalling, which have become known as the purinergic signalling system. With more than 50 components or processes, just at cell membranes, it ranks as one of the most versatile signalling systems. This multitude of system components may enable differentiated regulation of diverse epithelial functions. As epithelia probably face the widest variety of potential ATP-releasing stimuli, a special attention will be given to stimuli and mechanisms of ATP release with a focus on exocytosis. Subsequently, I will consider membrane transport of major ions (Cl(-) , HCO(3)(-) , K(+) and Na(+) ) and integrate possible regulatory functions of P2Y2, P2Y4, P2Y6, P2Y11, P2X4, P2X7 and adenosine receptors in some selected epithelia at the cellular level. Some purinergic receptors have noteworthy roles. For example, many studies to date indicate that the P2Y2 receptor is one common denominator in regulating ion channels on both the luminal and basolateral membranes of both secretory and absorptive epithelia. In exocrine glands though, P2X4 and P2X7 receptors act as cation channels and, possibly, as co-regulators of secretion. On an organ level, both receptor types can exert physiological functions and together with other partners in the purinergic signalling, integrated models for epithelial secretion and absorption are emerging.
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Affiliation(s)
- I Novak
- Department of Biology, August Krogh Building, University of Copenhagen, Denmark.
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Kongsuphol P, Schreiber R, Kraidith K, Kunzelmann K. CFTR induces extracellular acid sensing in Xenopus oocytes which activates endogenous Ca²⁺-activated Cl⁻ conductance. Pflugers Arch 2011; 462:479-87. [PMID: 21647592 DOI: 10.1007/s00424-011-0983-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 05/21/2011] [Accepted: 05/25/2011] [Indexed: 02/06/2023]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) produces a cyclic adenosine monophosphate (cAMP)-dependent Cl⁻ conductance of distinct properties that is essential for electrolyte secretion in human epithelial tissues. However, the functional consequences of CFTR expression are multifaceted, encompassing much more than simply supplying a cellular cAMP-regulated Cl⁻ conductance. When we expressed CFTR in Xenopus oocytes, we found that extracellular acidic pH activates a Ca²⁺-dependent outwardly rectifying Cl⁻ conductance that does not reflect CFTR activity. The proton-activated Cl⁻ conductance showed biophysical and pharmacological features of a Ca²⁺-dependent Cl⁻ conductance, most likely mediated by Xenopus TMEM16A. In contrast to the effects of extracellular acidification, intracellular acidification did not activate an endogenous Cl⁻ conductance. Proton/CFTR-mediated activation of human TMEM16A was also detected in HEK293 cells. The gating mutant G551D-CFTR conferred proton sensitivity, while deltaF508-CFTR enabled proton activation of TMEM16A only in Xenopus oocytes, which, unlike HEK293 cells, allow deltaF508-CFTR to be trafficked to the cell membrane. Activation of TMEM16A by lysophosphatidic acid was enhanced in the presence of CFTR but was additive with activation by extracellular protons. Because expression of CFTR-E1474X did not confer proton sensitivity, we propose that CFTR translocates a proton receptor to the plasma membrane via its PDZ-binding domain.
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Manzanares D, Gonzalez C, Ivonnet P, Chen RS, Valencia-Gattas M, Conner GE, Larsson HP, Salathe M. Functional apical large conductance, Ca2+-activated, and voltage-dependent K+ channels are required for maintenance of airway surface liquid volume. J Biol Chem 2011; 286:19830-9. [PMID: 21454692 DOI: 10.1074/jbc.m110.185074] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Large conductance, Ca(2+)-activated, and voltage-dependent K(+) (BK) channels control a variety of physiological processes in nervous, muscular, and renal epithelial tissues. In bronchial airway epithelia, extracellular ATP-mediated, apical increases in intracellular Ca(2+) are important signals for ion movement through the apical membrane and regulation of water secretion. Although other, mainly basolaterally expressed K(+) channels are recognized as modulators of ion transport in airway epithelial cells, the role of BK in this process, especially as a regulator of airway surface liquid volume, has not been examined. Using patch clamp and Ussing chamber approaches, this study reveals that BK channels are present and functional at the apical membrane of airway epithelial cells. BK channels open in response to ATP stimulation at the apical membrane and allow K(+) flux to the airway surface liquid, whereas no functional BK channels were found basolaterally. Ion transport modeling supports the notion that apically expressed BK channels are part of an apical loop current, favoring apical Cl(-) efflux. Importantly, apical BK channels were found to be critical for the maintenance of adequate airway surface liquid volume because continuous inhibition of BK channels or knockdown of KCNMA1, the gene coding for the BK α subunit (KCNMA1), lead to airway surface dehydration and thus periciliary fluid height collapse revealed by low ciliary beat frequency that could be fully rescued by addition of apical fluid. Thus, apical BK channels play an important, previously unrecognized role in maintaining adequate airway surface hydration.
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Affiliation(s)
- Dahis Manzanares
- Division of Pulmonary and Critical Care, University of Miami, Miami, Florida 33136, USA
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Kim Y, Kim H, Yoo HY, Kang JS, Kim SJ, Kim JK, Cho HS. Suppression of CFTR-mediated Cl secretion of airway epithelium in vitamin C-deficient mice. J Korean Med Sci 2011; 26:317-24. [PMID: 21394297 PMCID: PMC3051076 DOI: 10.3346/jkms.2011.26.3.317] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 12/24/2010] [Indexed: 11/23/2022] Open
Abstract
Hyperoxic ventilation induces detrimental effects on the respiratory system, and ambient oxygen may be harmful unless compensated by physiological anti-oxidants, such as vitamin C. Here we investigate the changes in electrolyte transport of airway epithelium in mice exposed to normobaric hyperoxia and in gulonolacton oxidase knock-out (gulo[-/-]) mice without vitamin C (Vit-C) supplementation. Short-circuit current (I(sc)) of tracheal epithelium was measured using Ussing chamber technique. After confirming amiloride-sensitive Na(+) absorption (ΔI(sc,amil)), cAMP-dependent Cl(-) secretion (ΔI(sc,forsk)) was induced by forskolin. To evaluate Ca(2+)-dependent Cl(-) secretion, ATP was applied to the luminal side (ΔI(sc,ATP)). In mice exposed to 98% PO(2) for 36 hr, ΔI(sc,forsk) decreased, ΔI(sc,amil) and ΔI(sc,ATP) was not affected. In gulo(-/-) mice, both ΔI(sc,forsk) and ΔI(sc,ATP) decreased from three weeks after Vit-C deprivation, while both were unchanged with Vit-C supplementation. At the fourth week, tissue resistance and all electrolyte transport activities were decreased. An immunofluorescence study showed that the expression of cystic fibrosis conductance regulator (CFTR) was decreased in gulo(-/-) mice, whereas the expression of KCNQ1 K(+) channel was preserved. Taken together, the CFTR-mediated Cl(-) secretion of airway epithelium is susceptible to oxidative stress, which suggests that supplementation of the antioxidant might be beneficial for the maintenance of airway surface liquid.
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Affiliation(s)
- Yeryung Kim
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyemin Kim
- Department of Anatomy, Seoul National University College of Medicine, Seoul, Korea
| | - Hae-Young Yoo
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
| | - Jae Seung Kang
- Department of Anatomy, Seoul National University College of Medicine, Seoul, Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea
| | - Jin Kyoung Kim
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyun Sung Cho
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Dutta AK, Khimji AK, Kresge C, Bugde A, Dougherty M, Esser V, Ueno Y, Glaser SS, Alpini G, Rockey DC, Feranchak AP. Identification and functional characterization of TMEM16A, a Ca2+-activated Cl- channel activated by extracellular nucleotides, in biliary epithelium. J Biol Chem 2010; 286:766-76. [PMID: 21041307 DOI: 10.1074/jbc.m110.164970] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Cl(-) channels in the apical membrane of biliary epithelial cells (BECs) provide the driving force for ductular bile formation. Although a cystic fibrosis transmembrane conductance regulator has been identified in BECs and contributes to secretion via secretin binding basolateral receptors and increasing [cAMP](i), an alternate Cl(-) secretory pathway has been identified that is activated via nucleotides (ATP, UTP) binding apical P2 receptors and increasing [Ca(2+)](i). The molecular identity of this Ca(2+)-activated Cl(-) channel is unknown. The present studies in human, mouse, and rat BECs provide evidence that TMEM16A is the operative channel and contributes to Ca(2+)-activated Cl(-) secretion in response to extracellular nucleotides. Furthermore, Cl(-) currents measured from BECs isolated from distinct areas of intrahepatic bile ducts revealed important functional differences. Large BECs, but not small BECs, exhibit cAMP-stimulated Cl(-) currents. However, both large and small BECs express TMEM16A and exhibit Ca(2+)-activated Cl(-) efflux in response to extracellular nucleotides. Incubation of polarized BEC monolayers with IL-4 increased TMEM16A protein expression, membrane localization, and transepithelial secretion (I(sc)). These studies represent the first molecular identification of an alternate, noncystic fibrosis transmembrane conductance regulator, Cl(-) channel in BECs and suggest that TMEM16A may be a potential target to modulate bile formation in the treatment of cholestatic liver disorders.
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Affiliation(s)
- Amal K Dutta
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9063, USA
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Pondugula SR, Raveendran NN, Marcus DC. Ion transport regulation by P2Y receptors, protein kinase C and phosphatidylinositol 3-kinase within the semicircular canal duct epithelium. BMC Res Notes 2010; 3:100. [PMID: 20398257 PMCID: PMC2862037 DOI: 10.1186/1756-0500-3-100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Accepted: 04/14/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The ionic composition of the luminal fluid in the vestibular labyrinth is maintained within tight limits by the many types of epithelial cells bounding the lumen. Regulatory mechanisms include systemic, paracrine and autocrine hormones along with their associated intracellular signal pathways. The epithelium lining the semicircular canal duct (SCCD) is a tissue that is known to absorb sodium and calcium and to secrete chloride. FINDINGS Transport function was assessed by measurements of short circuit current (Isc) and gene transcript expression was evaluated by microarray. Neither ATP nor UTP (100 microM) on the apical side of the epithelium had any effect on Isc. By contrast, basolateral ATP transiently increased Isc and transepithelial resistance dropped significantly after basolateral ATP and UTP. P2Y2 was the sole UTP-sensitive purinergic receptor expressed. Isc was reduced by 42%, 50% and 63% after knockdown of alpha-ENaC, stimulation of PKC and inhibition of PI3-K, while the latter two increased the transepithelial resistance. PKCdelta, PKCgamma and PI3-K were found to be expressed. CONCLUSIONS These observations demonstrate that ion transport by the SCCD is regulated by P2Y2 purinergic receptors on the basolateral membrane that may respond to systemic or local agonists, such as ATP and/or UTP. The sodium absorption from endolymph mediated by ENaC in SCCD is regulated by signal pathways that include the kinases PKC and PI3-K. These three newly-identified regulatory components may prove to be valuable drug targets in the control of pathologic vestibular conditions involving dysfunction of transport homeostasis in the ear, such as Meniere's disease.
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Flores CA, Cid LP, Sepúlveda FV, Niemeyer MI. TMEM16 proteins: the long awaited calcium-activated chloride channels? ACTA ACUST UNITED AC 2009; 42:993-1001. [PMID: 19784506 DOI: 10.1590/s0100-879x2009005000028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 08/12/2009] [Indexed: 11/22/2022]
Abstract
Currents mediated by calcium-activated chloride channels (CaCCs), observed for the first time in Xenopus oocytes, have been recorded in many cells and tissues ranging from different types of neurons to epithelial and muscle cells. CaCCs play a role in the regulation of excitability in neurons including sensory receptors. In addition, they are crucial mediators of chloride movements in epithelial cells where their activity regulates electrolyte and fluid transport. The roles of CaCCs, particularly in epithelia, are briefly reviewed with emphasis on their function in secretory epithelia. The recent identification by three independent groups, using different strategies, of TMEM16A as the molecular counterpart of the CaCC is discussed. TMEM16A is part of a family that has 10 other members in mice. The discovery of the potential TMEM16 anion channel activity opens the way for the molecular investigation of the role of these anion channels in specific cells and in organ physiology and pathophysiology. The identification of TMEM16A protein as a CaCC chloride channel molecule represents a great triumph of scientific perseverance and ingenuity. The varied approaches used by the three independent research groups also augur well for the solidity of the discovery.
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Affiliation(s)
- C A Flores
- Centro de Estudios Científicos (CECS), Valdivia, Chile
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O'Mullane LM, Cook DI, Dinudom A. Purinergic regulation of the epithelial Na+ channel. Clin Exp Pharmacol Physiol 2009; 36:1016-22. [PMID: 19566815 DOI: 10.1111/j.1440-1681.2009.05256.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
1. The epithelial Na(+) channel (ENaC) is a major conductive pathway that transports Na(+) across the apical membrane of the distal nephron, the respiratory tract, the distal colon and the ducts of exocrine glands. The ENaC is regulated by hormonal and humoral factors, including extracellular nucleotides that are available from the epithelial cells themselves. 2. Extracellular nucleotides, via the P2Y2 receptors (P2Y2Rs) at the basolateral and apical membrane of the epithelia, trigger signalling systems that inhibit the activity of the ENaC and activate Ca(2+) -dependent Cl(-) secretion. 3. Recent data from our laboratory suggest that stimulation of the P2Y2Rs at the basolateral membrane inhibits ENaC activity by a signalling mechanism that involves G beta gamma subunits freed from a pertussis toxin (PTX)-sensitive G-protein and phospholipase C (PLC) beta 4. A similar signalling mechanism is also partially responsible for inhibition of the ENaC during activation of apical P2Y2Rs. 4. Stimulation of apical P2Y2Rs also activates an additional signalling mechanism that inhibits the ENaC and involves the activated Galpha subunit of a PTX-insensitive G-protein and activation of an unidentified PLC. The effect of this PTX-insensitive system requires the activity of the basolateral Na(+)/K(+)/2Cl(-) cotransporter.
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Affiliation(s)
- Lauren M O'Mullane
- Discipline of Physiology, The Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, New South Wales, Australia
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Leydon C, Fisher KV, Lodewyck-Falciglia D. The cystic fibrosis transmembrane conductance regulator and chloride-dependent ion fluxes of ovine vocal fold epithelium. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2009; 52:745-754. [PMID: 18806217 DOI: 10.1044/1092-4388(2008/07-0192)] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
PURPOSE Ion-driven transepithelial water fluxes participate in maintaining superficial vocal fold hydration, which is necessary for normal voice production. The authors hypothesized that Cl(-) channels are present in vocal fold epithelial cells and that transepithelial Cl(-) fluxes can be manipulated pharmacologically. METHOD Immunohistochemical assays were used to identify cystic fibrosis transmembrane regulator Cl(-) channels in ovine vocal fold mucosae (n = 2). Electrophysiological responses of vocal fold mucosae (n = 80) to Cl(-) channel inhibitors and secretagogues were evaluated in an ovine model using a randomized controlled experimental design. RESULTS Cystic fibrosis transmembrane regulator channels were localized to the plasma membranes of epithelial cells. The Cl(-) transport inhibitor, diphenylamine-2-carboxylate, elicited a 30% decrease in mean short-circuit current (I(sc); n = 10). The secretagogue, isobutylmethylxanthine, yielded a 31.7% increase in mean I(sc) (n = 10). Another secretagogue, uridine triphosphate, elicited a 48.8% immediate and 17.3% sustained increase in mean I(sc) (n = 10). No sustained increases occurred following application of secretagogues to mucosae bathed in a low Cl(-) environment (n = 10), suggesting that responses were Cl(-) dependent. CONCLUSIONS The authors provide structural and functional evidence for the presence of a transepithelial pathway for Cl(-) fluxes. Pharmacological manipulation of this pathway may offer a mechanism for maintaining superficial vocal fold hydration.
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Affiliation(s)
- Ciara Leydon
- Department of Speech Communication Arts and Sciences, Brooklyn College of The City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA.
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Modulators of ion transport in nasal polyps: an in situ measurement of short-circuit current. Clin Exp Otorhinolaryngol 2009; 1:75-9. [PMID: 19434276 PMCID: PMC2671790 DOI: 10.3342/ceo.2008.1.2.75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 04/29/2008] [Indexed: 11/08/2022] Open
Abstract
Objectives To examine possible modulators of the ion transport through the apical membrane of the nasal polyps. Methods The study was conducted using the freshly-excised nasal polyps from the patients with chronic sinusitis. A voltage-sensitive vibrating probe technique was introduced to monitor the short-circuit current across the apical membrane of the polyp at 37℃. Results In the presence of amiloride, Adenosine 5'-triphosphate induced 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acidsensitive chloride current. Uridine 5'-diphosphate was less potent than Uridine 5'-triphosphate, and adenosine increased chloride secretion, which was blocked by the antagonist, 8-(p-sulfophenyl) theophylline on adenosine receptor. Based on the pharmacologic profiles, multiple purinergic receptors, including P2Y2, P2Y6, and P1 receptors, were functionally expressed. However, P2X receptor agonists (α,β-methyleneadenosine 5'-triphosphate and 2'- & 3'-O-[4-benzoyl-benzoyl] adenosine 5'-triphosphate), Cystic fibrosis conductance regulator (CFTR) activator (genistein), nitric oxide substrate (L-arginine), and nitric oxide donor (sodium nitroprusside) had no significant effect on the short circuit current. Conclusion Among tested drugs, P2Y receptor agonists were major modulators of ion transport in nasal polyps in situ.
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Warren NJ, Tawhai MH, Crampin EJ. A mathematical model of calcium-induced fluid secretion in airway epithelium. J Theor Biol 2009; 259:837-49. [PMID: 19442670 DOI: 10.1016/j.jtbi.2009.04.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 04/30/2009] [Accepted: 04/30/2009] [Indexed: 11/17/2022]
Abstract
Regulation of periciliary liquid (PCL) depth is of central importance to mucociliary clearance by the airway epithelium. Without adequate hydration mucociliary transport would cease, leading to build up of mucus in the airways, and impairing the clearance of any trapped inhaled particulates. Airway epithelial cells are known to release ATP under a number of stress conditions. Cell surface receptors bind ATP and trigger an intracellular calcium response which regulates the gating of specific ion channels on the apical and basolateral cell membranes. This shifts the electrochemical balance, resulting in the accumulation of Na(+) and Cl(-) in the periciliary liquid, and providing an osmotic driving force for water flux. In this study, we present a mathematical model of a single airway epithelial cell which describes the fluid secretion elicited after a rise in intracellular calcium. The model provides a basis to quantitatively analyse the influence of intracellular calcium signalling on fluid movement. The model demonstrates behaviour consistent with a number of experimental data on manipulating periciliary liquid volume and tonicity, and provides a quantitative basis for analysing the role of the different membrane ion channels in determining water flux following different physiological stimuli.
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Affiliation(s)
- N J Warren
- Auckland Bioengineering Institute, CBD, Auckland, New Zealand.
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36
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Martino MEB, Olsen JC, Fulcher NB, Wolfgang MC, O'Neal WK, Ribeiro CMP. Airway epithelial inflammation-induced endoplasmic reticulum Ca2+ store expansion is mediated by X-box binding protein-1. J Biol Chem 2009; 284:14904-13. [PMID: 19321437 DOI: 10.1074/jbc.m809180200] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inflamed cystic fibrosis (CF) human bronchial epithelia (HBE), or normal HBE exposed to supernatant from mucopurulent material (SMM) from CF airways, exhibit endoplasmic reticulum (ER)/Ca(2+) store expansion and amplified Ca(2+)-mediated inflammation. HBE inflammation triggers an unfolded protein response (UPR) coupled to mRNA splicing of X-box binding protein-1 (XBP-1). Because spliced XBP-1 (XBP-1s) promotes ER expansion in other cellular models, we hypothesized that XBP-1s is responsible for the ER/Ca(2+) store expansion in inflamed HBE. XBP-1s was increased in freshly isolated infected/inflamed CF in comparison with normal HBE. The link between airway epithelial inflammation, XBP-1s, and ER/Ca(2+) store expansion was then addressed in murine airways challenged with phosphate-buffered saline or Pseudomonas aeruginosa. P. aeruginosa-challenged mice exhibited airway epithelial ER/Ca(2+) store expansion, which correlated with airway inflammation. P. aeruginosa-induced airway inflammation triggered XBP-1s in ER stress-activated indicator (ERAI) mice. To evaluate the functional role of XBP-1s in airway inflammation linked to ER/Ca(2+) store expansion, control, XBP-1s, or dominant negative XBP-1 (DN-XBP-1) stably expressing 16HBE14o(-) cell lines were used. Studies with cells transfected with an unfolded protein response element (UPRE) luciferase reporter plasmid confirmed that the UPRE was activated or inhibited by expression of XBP-1s or DN-XBP-1, respectively. Expression of XBP-1s induced ER/Ca(2+) store expansion and potentiated bradykinin-increased interleukin (IL)-8 secretion, whereas expression of DN-XBP-1 inhibited bradykinin-dependent IL-8 secretion. In addition, expression of DN-XBP-1 blunted SMM-induced ER/Ca(2+) store expansion and SMM-induced IL-8 secretion. These findings suggest that, in inflamed HBE, XBP-1s is responsible for the ER/Ca(2+) store expansion that confers amplification of Ca(2+)-dependent inflammatory responses.
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Affiliation(s)
- Mary E B Martino
- Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Eichstaedt S, Gäbler K, Below S, Müller C, Hildebrandt JP. Phospholipase C-activating plasma membrane receptors and calcium signaling in immortalized human airway epithelial cells. J Recept Signal Transduct Res 2009; 28:591-612. [PMID: 19096976 DOI: 10.1080/10799890802407120] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Mechanical clearance of inhaled dust particles and microorganisms is an important part of the innate defense mechanisms of mammalian airways. Airway epithelia are composed of various cell types with different degrees of cell polarity. Serous cells regulate composition and volume of luminal periciliary fluid and mucus. Autocrine, paracrine, or neuronal messengers determine the secretory and reabsorptive rates of electrolytes and water via cAMP-or inositol triphosphate/calcium-mediated intracellular signals. Comparison of the expression of calcium-mobilizing receptor types (G protein-coupled-, growth factor-, and cytokine receptors) in two types of human immortalized airway epithelial cells (S9, 16HBE14o-) revealed that receptor populations were qualitatively and quantitatively different in the two cell types. Sustained calcium signals were elicited by activation of purinergic receptors in 16HBE14o-cells or muscarinic acetylcholine or histamine receptors in S9 cells. These G protein-coupled receptors mobilized calcium from intracellular stores and activated capacitative calcium influx. The experimental cells may represent different types of original airway epithelial cells and seem to be suited as model cells to study cell signaling and protein expression during interaction with pathogens or their secretory products (e.g., virulence factors).
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Affiliation(s)
- Stefanie Eichstaedt
- Animal Physiology and Biochemistry, Zoological Institute, Greifswald, Germany
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Abstract
Adenosine (Ado) regulates diverse cellular functions in the lung through its local production, release, metabolism, and subsequent stimulation of G-protein-coupled P1 purinergic receptors. The A(2B) adenosine receptor (A(2B)AR) is the predominant P1 purinergic receptor isoform expressed in surface airway epithelia, and Ado is an important regulator of airway surface liquid (ASL) volume through its activation of the cystic fibrosis transmembrane conductance regulator (CFTR). Through a delicate balance between sodium (Na(+)) absorption and chloride (Cl(-)) secretion, the ASL volume is optimized to promote ciliary activity and mucociliary clearance, effectively removing inhaled particulates. When CFTR is dysfunctional, the Ado/A(2B)AR regulatory system fails to optimize the ASL volume, leading to its depletion and interruption of mucociliary clearance. In cystic fibrosis (CF), loss of CFTR function and resultant mucus stasis leaves the lower airways susceptible to mucus obstruction, chronic bacterial infection, relentless inflammation, and eventually panbronchiectasis. Adenosine triphosphate (ATP) also regulates transepithelial Cl(-) conductance, but through a separate system that relies on stimulation of P2Y(2) purinergic receptors, mobilization of intracellular calcium, and activation of calcium-activated chloride channels (CaCCs). These pathways remain functional in CF, and may serve a protective role in the disease. In this chapter, we will review our current understanding of how Ado and related nucleotides regulate CFTR and Cl(-) conductance in the human airway, including the regulation of additional intracellular and extracellular signaling pathways that provide important links between ion transport and inflammation relevant to the disease.
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Wong AM, Chow AW, Au SC, Wong CC, Ko WH. Apical versus basolateral P2Y(6) receptor-mediated Cl(-) secretion in immortalized bronchial epithelia. Am J Respir Cell Mol Biol 2008; 40:733-45. [PMID: 19011163 DOI: 10.1165/rcmb.2008-0020oc] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Apical and/or basolateral membranes of polarized epithelia express P2Y receptors, which regulate the transport of fluid and electrolytes. In the airway, P2Y receptors modulate Cl(-) secretion through the phospholipase C and calcium signaling pathways. Recent evidence suggests that P2Y(6) receptors are expressed in bronchial epithelium and coupled to the cAMP/protein kinase A (PKA) pathways. We examined P2Y receptor subtype expression, including P2Y(6,) and the effect of extracellular nucleotides on basal short-circuit current (I(SC)) and intracellular calcium concentration ([Ca(2+)](i)) in a human bronchial epithelial cell line (16HBE14o-). Real-time PCR demonstrated P2Y(1), P2Y(2), P2Y(4), and P2Y(6) receptor expression and confirmed that transcript levels were not altered when cells were grown under varied conditions. It was determined that P2Y agonists (ATP, UTP, UDP) stimulated a concomitant increase in I(SC) and [Ca(2+)](i). Apical nucleotides stimulated an increase in [Ca(2+)](i) more efficiently than basolateral nucleotides; however, P2Y agonistic effects on I(SC) were greater when applied basolaterally. Since the P2Y(6) receptors differentially regulate apical and basolateral UDP-induced I(SC) and [Ca(2+)](i), we investigated membrane-resident P2Y(6) receptor functions using Cl(-) or K(+) channels blockers. Apical and basolateral UDP activation of I(SC) was inhibited by applying DIDS apically or TRAM-34 and clotrimazole basolaterally. Although both apical and basolateral UDP increased PKA activity, only apical UDP-induced I(SC) was sensitive to a CFTR inhibitor. These data demonstrate that P2Y agonists stimulate Ca(2+)-dependent Cl(-) secretion across human bronchial epithelia and that the cAMP/PKA pathway regulates apical but not basolateral P2Y(6) receptor-coupled ion transport in human bronchial epithelia.
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Affiliation(s)
- Alison M Wong
- Department of Physiology, The Chinese University of Hong Kong, Shatin, Hong Kong
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Bestrophin 1 and 2 are components of the Ca2+ activated Cl− conductance in mouse airways. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1993-2000. [DOI: 10.1016/j.bbamcr.2008.06.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2008] [Revised: 06/18/2008] [Accepted: 06/23/2008] [Indexed: 11/21/2022]
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Norez C, Vandebrouck C, Antigny F, Dannhoffer L, Blondel M, Becq F. Guanabenz, an α2-selective adrenergic agonist, activates Ca2+-dependent chloride currents in cystic fibrosis human airway epithelial cells. Eur J Pharmacol 2008; 592:33-40. [DOI: 10.1016/j.ejphar.2008.06.103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Revised: 06/19/2008] [Accepted: 06/27/2008] [Indexed: 11/26/2022]
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Illek B, Fu Z, Schwarzer C, Banzon T, Jalickee S, Miller SS, Machen TE. Flagellin-stimulated Cl- secretion and innate immune responses in airway epithelia: role for p38. Am J Physiol Lung Cell Mol Physiol 2008; 295:L531-42. [PMID: 18658272 DOI: 10.1152/ajplung.90292.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of an innate immune response in airway epithelia by the human pathogen Pseudomonas aeruginosa requires bacterial expression of flagellin. Addition of flagellin (10(-7) M) to airway epithelial cell monolayers (Calu-3, airway serous cell-like) increased Cl(-) secretion (I(Cl)) beginning after 3-10 min, reaching a plateau after 20-45 min at DeltaI(Cl) = 15-50 microA/cm(2). Similar, although 10-fold smaller, responses were observed in well-differentiated bronchial epithelial cultures. Flagellin stimulated I(Cl) in the presence of maximally stimulating doses of the purinergic agonist ATP, but had no effects following forskolin. IL-1beta (produced by both epithelia and neutrophils during infections) stimulated I(Cl) similar to flagellin. Flagellin-, IL-1beta-, ATP-, and forskolin-stimulated I(Cl) were inhibited by cystic fibrosis transmembrane conductance regulator (CFTR) blockers GlyH101, CFTRinh172, and glibenclamide. Neither flagellin nor IL-1beta altered transepithelial fluxes of membrane-impermeant dextran (10 kDa) or lucifer yellow (mol wt = 457), but both activated p38, NF-kappaB, and IL-8 secretion. Blockers of p38 (SB-202190 and SB-203580) reduced flagellin- and IL-1beta-stimulated I(Cl) by 33-50% but had smaller effects on IL-8 and NF-kappaB. It is concluded that: 1) flagellin and IL-1beta activated p38, NF-kappaB, IL-8, and CFTR-dependent anion secretion without altering tight junction permeability; 2) p38 played a role in regulating I(Cl) and IL-8 but not NF-kappaB; and 3) p38 was more important in flagellin- than IL-1beta-stimulated responses. During P. aeruginosa infections, flagellin and IL-1beta are expected to increase CFTR-dependent ion and fluid flow into and bacterial clearance from the airways. In cystic fibrosis, the secretory response would be absent, but activation of p38, NF-kappaB, and IL-8 would persist.
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Affiliation(s)
- Beate Illek
- Dept. of Molecular and Cell Biology, Univ. of California-Berkeley, Berkeley, CA 94720-3200, USA
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Button B, Boucher RC. Role of mechanical stress in regulating airway surface hydration and mucus clearance rates. Respir Physiol Neurobiol 2008; 163:189-201. [PMID: 18585484 DOI: 10.1016/j.resp.2008.04.020] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 04/11/2008] [Accepted: 04/11/2008] [Indexed: 11/16/2022]
Abstract
Effective clearance of mucus is a critical innate airway defense mechanism, and under appropriate conditions, can be stimulated to enhance clearance of inhaled pathogens. It has become increasingly clear that extracellular nucleotides (ATP and UTP) and nucleosides (adenosine) are important regulators of mucus clearance in the airways as a result of their ability to stimulate fluid secretion, mucus hydration, and cilia beat frequency (CBF). One ubiquitous mechanism to stimulate ATP release is through external mechanical stress. This article addresses the role of physiologically relevant mechanical forces in the lung and their effects on regulating mucociliary clearance (MCC). The effects of mechanical forces on the stimulating ATP release, fluid secretion, CBF, and MCC are discussed. Also discussed is evidence suggesting that airway hydration and stimulation of MCC by stress-mediated ATP release may play a role in several therapeutic strategies directed at improving mucus clearance in patients with obstructive lung diseases, including cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD).
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Affiliation(s)
- Brian Button
- Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7248, USA.
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Keating N, Quinlan LR. Effect of basolateral adenosine triphosphate on chloride secretion by bovine oviductal epithelium. Biol Reprod 2008; 78:1119-26. [PMID: 18322271 DOI: 10.1095/biolreprod.107.065508] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The composition of the fluid within the oviduct is largely determined by the secretory and absorptive activities of the oviduct epithelium. The present study explored the effects of basolateral nucleotide stimulation on ion transport in the bovine oviduct using the chamber short-circuit current technique. Basolateral application of ATP induced a rapid transient increase in ion secretion by oviduct epithelial monolayers in a concentration-dependent manner. The ATP-induced short-circuit current (I(SC)) response was preserved in the presence of amiloride, whereas it was reduced in the absence of extracellular chloride or in the presence of bumetanide. The channels underlying the chloride secretory response were identified as Ca(2+)-activated Cl(-) channels and CFTR. The ATP-induced Cl(-) secretory response was largely preserved in the absence of extracellular Ca(2+) but was significantly reduced in the presence of BAPTA-am (1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid-acetomethoxy ester), thapsigargin, or 2-APB (2-aminoethoxydiphenylborate), demonstrating an important role for intracellular Ca(2+) signaling in mediating these effects. A nucleotide potency profile of ATP = UTP (uridine triphosphate) > ADP, sensitivity to suramin, and cross-desensitization by basolateral UTP suggests that ATP exerted its effects on chloride secretion through the purinergic receptor P2Y, G protein-coupled 2, and the presence of the P2RY2 gene was confirmed by RT-PCR. These results provide strong evidence that purinergic signaling constitutes a key mechanism of regulating chloride secretion and thus fluid formation in the bovine oviduct.
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Affiliation(s)
- N Keating
- Department of Physiology, National University of Ireland Galway, Galway, Ireland
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Köles L, Gerevich Z, Oliveira JF, Zadori ZS, Wirkner K, Illes P. Interaction of P2 purinergic receptors with cellular macromolecules. Naunyn Schmiedebergs Arch Pharmacol 2007; 377:1-33. [DOI: 10.1007/s00210-007-0222-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 11/12/2007] [Indexed: 02/04/2023]
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Livraghi A, Mall M, Paradiso AM, Boucher RC, Ribeiro CMP. Modelling dysregulated Na+ absorption in airway epithelial cells with mucosal nystatin treatment. Am J Respir Cell Mol Biol 2007; 38:423-34. [PMID: 17989361 DOI: 10.1165/rcmb.2007-0177oc] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In cystic fibrosis (CF), the absence of functional CFTR leads to dysregulated Na(+) absorption across airway epithelia. We established an in vitro model of dysregulated Na(+) absorption by treating polarized normal human bronchial epithelial cells (HBEs) with nystatin (Nys), a polyene antibiotic that enables monovalent cations to permeate biological membranes. Acute mucosal Nys produced a rapid increase in short circuit current (I(sc)) that reflected increased transepithelial Na(+) absorption and required Na(+)/K(+)ATPase activity. The acute increase in I(sc) was associated with increased mucosal liquid absorption. Prolonged mucosal Nys treatment resulted in sustained Na(+) hyperabsorption, associated with increased mucosal liquid absorption in comparison with naïve (nontreated, kept under air-liquid interface conditions) or vehicle-treated cultures. Nys treatment was not toxic. Increased lactate accumulation in Nys-treated culture media suggested a higher metabolic rate associated with the higher energy demand for Na(+) transport. After chronic Nys treatment, the increased I(sc) was rapidly lost when the cultures were mounted in Ussing chambers, indicating that Nys could be rapidly removed from the apical membrane. Importantly, chronic Nys treatment promoted sustained mucosal liquid depletion and caused mucus dehydration, compaction, and adhesion to the apical surface of Nys-treated cultures. We conclude that mucosal Nys treatment of HBEs provides a simple in vitro model to recapitulate the Na(+) and volume hyperabsorptive features of CF airway epithelia.
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Affiliation(s)
- Alessandra Livraghi
- University of North Carolina at Chapel Hill, Cystic Fibrosis/Pulmonary Research and Treatment Center, CB#7248 Thurston Bowles Bldg., Room # 6029, Chapel Hill, NC 27599, USA.
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Norez C, Antigny F, Becq F, Vandebrouck C. Maintaining low Ca2+ level in the endoplasmic reticulum restores abnormal endogenous F508del-CFTR trafficking in airway epithelial cells. Traffic 2007; 7:562-73. [PMID: 16643279 DOI: 10.1111/j.1600-0854.2006.00409.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The most common mutation in cystic fibrosis, F508del, results in cystic fibrosis transmembrane conductance regulator protein (CFTR) that is retained in the endoplasmic reticulum (ER). Retention is dependent on chaperone proteins, many of which, like calnexin, require calcium for optimal activity. Here, we show that a limited and a maintained ER calcium level is sufficient to inhibit the F508del-CFTR/calnexin interaction and to restore the cAMP-dependent CFTR chloride transport, thus showing the correction of abnormal trafficking. We used Western blot analysis, iodide efflux and calcium measurement techniques applied to the human airway epithelial cystic fibrosis cell line CF15 (F508del/F508del). The inhibition of ER calcium pump, with thapsigargin, curcumin, 2,5-di(t-butyl)hydroquinone or cyclopiazonic acid, maintains a threshold levels of calcium that is correlated to the recovery of endogenous F508del-CFTR transport activity. In particular, cyclopiazonic acid restores a 2-aminoethyoxydiphenyl borate-sensitive F508del-CFTR trafficking with an EC50 of 915 nm. By contrast, the 1,4,5-trisphosphate or IP3 receptor activators, i.e., ATP and histamine, while transiently emptying the ER intracellular calcium store, did not affect the trafficking of F508del-CFTR. Our data suggest that decreasing the ER calcium level is not sufficient to restore the defective trafficking of F508del-CFTR, whereas decreasing and also maintaining low ER calcium level allow correction of defective biosynthetic pathway of endogenous F508del-CFTR in human airway epithelial cells.
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Affiliation(s)
- Caroline Norez
- Institut de Physiologie et Biologie Cellulaires CNRS UMR 6187, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers, France
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Shin JH, Son EJ, Lee HS, Kim SJ, Kim K, Choi JY, Lee MG, Yoon JH. Molecular and functional expression of anion exchangers in cultured normal human nasal epithelial cells. Acta Physiol (Oxf) 2007; 191:99-110. [PMID: 17635413 PMCID: PMC2040222 DOI: 10.1111/j.1748-1716.2007.01731.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Aims Anions have an important role in the regulation of airway surface liquid (ASL) volume, viscosity and pH. However, functional localization and regulation of anion exchangers (AEs) have not been clearly described. The aim of this study was to investigate the regulation of AE mRNA expression level in accordance with mucociliary differentiation and the functional expression of AEs cultured normal human nasal epithelial (NHNE) cells. Methods Nasal mucosal specimens from three patients are obtained and serially cultured cells are subjected to morphological examinations, RT-PCR, Western blot analysis and immunocytochemistry. AE activity is assessed by pHi measurements. Results Expression of ciliated cells on the apical membrane and expression of MUC5AC, a marker of mucous differentiation, increased with time. AE2 and SLC26A4 mRNA expression decreased as mucociliary differentiation progressed, and AE4, SLC26A7 and SLC26A8 mRNA expression increased on the 14th and 28th day after confluence. Accordingly, AE4 protein expression also progressively increased. AE activity in 100 mm K+ buffer solutions was nearly twofold higher than that in 5 mm K+ buffer solutions. Moreover, only luminal AE activity increased about fourfold over the control in the presence of 5 μm forskolin. In the presence of 100 μm adenosine-5′-triphosphate (ATP) which evokes intracellular calcium signalling through activation of purinergic receptors, only luminal AE activity was again significantly increased. On the other hand, 500 μm 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS), an inhibitor of most SLC4 and SLC26AE isoforms, nearly abolished AE activity in both luminal and basolateral membranes. We found that AE activity was affected by intracellular cAMP and calcium signalling in the luminal membrane and was DIDS-sensitive in both membranes of cultured NHNE cells. Conclusion Our findings through molecular and functional studies using cultured NHNE cells suggest that AEs may have an important role in the regulation of ASL.
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Affiliation(s)
- J-H Shin
- The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Korea
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Is Intervention in Inositol Phosphate Signaling a Useful Therapeutic Option for Cystic Fibrosis? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007. [DOI: 10.1007/0-387-23250-8_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Antigny F, Norez C, Becq F, Vandebrouck C. Calcium homeostasis is abnormal in cystic fibrosis airway epithelial cells but is normalized after rescue of F508del-CFTR. Cell Calcium 2007; 43:175-83. [PMID: 17590432 DOI: 10.1016/j.ceca.2007.05.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 04/20/2007] [Accepted: 05/08/2007] [Indexed: 11/19/2022]
Abstract
Retention of F508del-CFTR proteins in the endoplasmic reticulum (ER) is dependent upon chaperone proteins, many of which require Ca(2+) for optimal activity. Here, we show in human tracheal gland CF-KM4 cells, that after correction of F508del-CFTR trafficking by miglustat (N-butyldeoxynojirimycin) or low temperature (27 degrees C), the Ca(2+) mobilization is decreased compared to uncorrected cells and becomes identical to the Ca(2+) response observed in non-CF MM39 cells. In CF-KM4 and human nasal epithelial CF15 cells, we also show that inhibiting vesicular trafficking by nocodazole prevents not only the rescue of F508del-CFTR but also the Ca(2+) mobilization decrease. Finally, experiments using the CFTR inhibitor CFTR(inh)-172 showed that the presence but not the channel activity of F508del-CFTR at the plasma membrane is required to decrease the Ca(2+) mobilization in corrected CF cells. These findings show that correction of the abnormal trafficking of F508del-CFTR proteins might have profound consequences on cellular homeostasis such as the control of intracellular Ca(2+) level.
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Affiliation(s)
- Fabrice Antigny
- Institut de Physiologie et de Biologie Cellulaires, Université de Poitiers, CNRS UMR 6187, Poitiers Cedex, France
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