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Schreiber R, Ousingsawat J, Kunzelmann K. The anoctamins: Structure and function. Cell Calcium 2024; 120:102885. [PMID: 38642428 DOI: 10.1016/j.ceca.2024.102885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/22/2024]
Abstract
When activated by increase in intracellular Ca2+, anoctamins (TMEM16 proteins) operate as phospholipid scramblases and as ion channels. Anoctamin 1 (ANO1) is the Ca2+-activated epithelial anion-selective channel that is coexpressed together with the abundant scramblase ANO6 and additional intracellular anoctamins. In salivary and pancreatic glands, ANO1 is tightly packed in the apical membrane and secretes Cl-. Epithelia of airways and gut use cystic fibrosis transmembrane conductance regulator (CFTR) as an apical Cl- exit pathway while ANO1 supports Cl- secretion mainly by facilitating activation of luminal CFTR and basolateral K+ channels. Under healthy conditions ANO1 modulates intracellular Ca2+ signals by tethering the endoplasmic reticulum, and except of glands its direct secretory contribution as Cl- channel might be small, compared to CFTR. In the kidneys ANO1 supports proximal tubular acid secretion and protein reabsorption and probably helps to excrete HCO3-in the collecting duct epithelium. However, under pathological conditions as in polycystic kidney disease, ANO1 is strongly upregulated and may cause enhanced proliferation and cyst growth. Under pathological condition, ANO1 and ANO6 are upregulated and operate as secretory channel/phospholipid scramblases, partly by supporting Ca2+-dependent processes. Much less is known about the role of other epithelial anoctamins whose potential functions are discussed in this review.
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Affiliation(s)
- Rainer Schreiber
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany.
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2
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Eisenhut M. Rhinorrhea and increased chloride secretion through the CFTR chloride channel-a systematic review. Eur Arch Otorhinolaryngol 2023; 280:4309-4318. [PMID: 37338585 DOI: 10.1007/s00405-023-08067-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/12/2023] [Indexed: 06/21/2023]
Abstract
PURPOSE Allergic and non-allergic rhinorrhea in the forms of acute or chronic rhinosinusitis can mean a watery nasal discharge that is disabling. Primary objective was to review the evidence supporting the hypothesis that rhinorrhea is due to increased chloride secretion through the CFTR chloride channel. METHODS The structure of the evidence review followed the EQUATOR Reporting Guidelines. Databases searched from inception to February 2022 included Pubmed, EMBASE and the Cochrane library using keywords "Rhinorrhea", "chloride", "chloride channel", "CFTR" and "randomized controlled trial". Quality assessment was according to the Oxford Centre for Evidence-based Medicine. RESULTS 49 articles were included. They included randomized controlled trials out of which subsets of data with the outcome of rhinorrhea on 6038 participants were analysed and in vitro and animal studies. The review revealed that drugs, which activate CFTR are associated with rhinorrhea. Viruses, which cause rhinorrhea like rhinovirus were found to activate CFTR. The chloride concentration in nasal fluid showed an increase in patients with viral upper respiratory tract infection. Increased hydrostatic tissue pressure, which is an activator of CFTR was observed in allergic upper airway inflammation. In this condition exhaled breath condensate chlorine concentration was found to be significantly increased. Drugs, which can reduce CFTR function including steroids, anti-histamines, sympathomimetic and anticholinergic drugs reduced rhinorrhea in randomized controlled trials. CONCLUSIONS A model of CFTR activation-mediated rhinorrhea explains the effectiveness of anticholinergic, sympathomimetic, anti-histamine and steroid drugs in reducing rhinorrhea and opens up avenues for further improvement of treatment by already known specific CFTR inhibitors.
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Affiliation(s)
- Michael Eisenhut
- Paediatric Department, Luton and Dunstable University Hospital, Luton, LU40DZ, UK.
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3
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Differential CFTR-Interactome Proximity Labeling Procedures Identify Enrichment in Multiple SLC Transporters. Int J Mol Sci 2022; 23:ijms23168937. [PMID: 36012204 PMCID: PMC9408702 DOI: 10.3390/ijms23168937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022] Open
Abstract
Proteins interacting with CFTR and its mutants have been intensively studied using different experimental approaches. These studies provided information on the cellular processes leading to proper protein folding, routing to the plasma membrane, recycling, activation and degradation. Recently, new approaches have been developed based on the proximity labeling of protein partners or proteins in close vicinity and their subsequent identification by mass spectrometry. In this study, we evaluated TurboID- and APEX2-based proximity labeling of WT CFTR and compared the obtained data to those reported in databases. The CFTR-WT interactome was then compared to that of two CFTR (G551D and W1282X) mutants and the structurally unrelated potassium channel KCNK3. The two proximity labeling approaches identified both known and additional CFTR protein partners, including multiple SLC transporters. Proximity labeling approaches provided a more comprehensive picture of the CFTR interactome and improved our knowledge of the CFTR environment.
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4
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Abdel Hameid R, Cormet-Boyaka E, Kuebler WM, Uddin M, Berdiev BK. SARS-CoV-2 may hijack GPCR signaling pathways to dysregulate lung ion and fluid transport. Am J Physiol Lung Cell Mol Physiol 2021; 320:L430-L435. [PMID: 33434105 PMCID: PMC7938641 DOI: 10.1152/ajplung.00499.2020] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a virus responsible for the ongoing coronavirus disease 2019 (COVID-19) pandemic, toward the host cells is determined, at least in part, by the expression and distribution of its cell surface receptor, angiotensin-converting enzyme 2 (ACE2). The virus further exploits the host cellular machinery to gain access into the cells; its spike protein is cleaved by a host cell surface transmembrane serine protease 2 (TMPRSS2) shortly after binding ACE2, followed by its proteolytic activation at a furin cleavage site. The virus primarily targets the epithelium of the respiratory tract, which is covered by a tightly regulated airway surface liquid (ASL) layer that serves as a primary defense mechanism against respiratory pathogens. The volume and viscosity of this fluid layer is regulated and maintained by a coordinated function of different transport pathways in the respiratory epithelium. We argue that SARS-CoV-2 may potentially alter evolutionary conserved second-messenger signaling cascades via activation of G protein-coupled receptors (GPCRs) or by directly modulating G protein signaling. Such signaling may in turn adversely modulate transepithelial transport processes, especially those involving cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial Na+ channel (ENaC), thereby shifting the delicate balance between anion secretion and sodium absorption, which controls homeostasis of this fluid layer. As a result, activation of the secretory pathways including CFTR-mediated Cl− transport may overwhelm the absorptive pathways, such as ENaC-dependent Na+ uptake, and initiate a pathophysiological cascade leading to lung edema, one of the most serious and potentially deadly clinical manifestations of COVID-19.
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Affiliation(s)
- Reem Abdel Hameid
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | | | - Wolfgang M Kuebler
- Institute of Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Mohammed Uddin
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates.,The Centre for Applied Genomics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Bakhrom K Berdiev
- Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
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5
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Wang Y, Zhao J, Cai Y, Ballard HJ. Cystic fibrosis transmembrane conductance regulator-dependent bicarbonate entry controls rat cardiomyocyte ATP release via pannexin1 through mitochondrial signalling and caspase activation. Acta Physiol (Oxf) 2020; 230:e13495. [PMID: 32386453 DOI: 10.1111/apha.13495] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 04/27/2020] [Accepted: 05/01/2020] [Indexed: 12/20/2022]
Abstract
AIM Cystic fibrosis transmembrane conductance regulator (CFTR) is expressed in the heart, but its function there is unclear. CFTR regulates an ATP release pore in many tissues, but the identity and regulatory mechanism of the pore are unknown. We investigated the role of CFTR in ATP release from primary cardiomyocytes and ventricular wall in vivo. METHODS Proteins involved in the signalling pathway for ATP release during simulated ischaemia (lactic acid treatment) were investigated using inhibitors and siRNA; colocalization was identified by coimmunofluorescence and proximity ligation assays; changes in near-membrane pH and calcium were identified with total internal reflection microscopy; in vivo ATP release was investigated using interstitial microdialysis of rat heart. RESULTS Lactic acid-induced CFTR-dependent ATP release from cultured cardiomyocytes and left ventricle in vivo. Lactic acid entry elevated near-membrane calcium, which involved Na/H- and Na/Ca-exchangers colocalized with CFTR. Calcium entry-induced CFTR activation, which involved cAMP, protein kinase A, FAK, Pyk2 and Src. Removal of extracellular bicarbonate abolished cardiomyocyte ATP release induced by lactic acid or CFTR activators. Bicarbonate stimulated cytochrome c expression, cytochrome c release and ATP release from isolated cardiomyocyte mitochondria. Pannexin 1 (Panx1) colocalized with CFTR. Lactic acid increased cardiomyocyte caspase activity: caspase inhibitors or Panx1 siRNA abolished cardiomyocyte ATP release, while pannexin inhibition abolished cardiac ATP release in vivo. CONCLUSION During simulated ischaemia, CFTR-dependent bicarbonate entry stimulated ATP and cytochrome c release from mitochondria; in the cytoplasm, cytochrome c-activated caspase 3, which in turn activated Panx1, and ATP was released through the opened Panx1 channel.
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Affiliation(s)
- Yongshun Wang
- School of Biomedical Sciences The University of Hong Kong Pokfulam Hong Kong
| | - Junjun Zhao
- School of Biomedical Sciences The University of Hong Kong Pokfulam Hong Kong
| | - Yin Cai
- Department of Anaesthesiology The University of Hong Kong Pokfulam Hong Kong
| | - Heather J. Ballard
- School of Biomedical Sciences The University of Hong Kong Pokfulam Hong Kong
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6
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Yeh KM, Johansson O, Le H, Rao K, Markus I, Perera DS, Lubowski DZ, King DW, Zhang L, Chen H, Liu L. Cystic fibrosis transmembrane conductance regulator modulates enteric cholinergic activities and is abnormally expressed in the enteric ganglia of patients with slow transit constipation. J Gastroenterol 2019; 54:994-1006. [PMID: 31392489 DOI: 10.1007/s00535-019-01610-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/31/2019] [Indexed: 02/04/2023]
Abstract
BACKGROUND Cystic fibrosis transmembrane conductance regulator (CFTR) was recently found in the enteric nervous system, where its role is unclear. We aimed to identify which enteric neuronal structures express CFTR, whether CFTR modulates enteric neurotransmission and if altered CFTR expression is associated with slow transit constipation (STC). METHODS Immunofluorescence double labeling was performed to localize CFTR with various neuronal and glial cell markers in the human colon. The immunoreactivity (IR) of CFTR and choline acetyltransferase (ChAT) on myenteric plexus of control and STC colon was quantitatively analyzed. In control colonic muscle strips, electrical field stimulation (EFS) evoked contractile responses and the release of acetylcholine (ACh) was measured in the presence of the CFTR channel inhibitor, CFTR(inh)-172. RESULTS CFTR-IR was densely localized to myenteric ganglia, where it was co-localized with neuronal markers HuC/D and β-tubulin, and glial marker S-100 but little with glial fibrillary acidic protein. Vesicular ACh transport was almost exclusively co-localized with CFTR, but neurons expressing nitric oxide synthase were CFTR negative. Significant reductions of CFTR-IR (P < 0.01) and ChAT-IR (P < 0.05) were observed on myenteric ganglia of STC compared to control. Pre-treatment of colonic muscle strips with CFTR(inh)-172 (10 µM) significantly inhibited EFS-evoked contractile responses (P < 0.01) and ACh release (P < 0.05). CONCLUSIONS Co-localization of CFTR-IR with cholinergic markers, inhibition of EFS-induced colonic muscle contractility and ACh release by CFTR(inh)-172 suggest that CFTR modulates enteric cholinergic neurotransmission. The downregulation of CFTR and ChAT in myenteric ganglia of STC correlated with the impaired contractile responses to EFS.
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Affiliation(s)
- Ka Ming Yeh
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Olle Johansson
- Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Huy Le
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Karan Rao
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Irit Markus
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | | | | | | | - Li Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Hongzhuan Chen
- School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lu Liu
- Department of Pharmacology, Faculty of Medicine, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
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7
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Marklew AJ, Patel W, Moore PJ, Tan CD, Smith AJ, Sassano MF, Gray MA, Tarran R. Cigarette Smoke Exposure Induces Retrograde Trafficking of CFTR to the Endoplasmic Reticulum. Sci Rep 2019; 9:13655. [PMID: 31541117 PMCID: PMC6754399 DOI: 10.1038/s41598-019-49544-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 08/12/2019] [Indexed: 12/16/2022] Open
Abstract
Chronic obstructive pulmonary disease (COPD), which is most commonly caused by cigarette smoke (CS) exposure, is the third leading cause of death worldwide. The cystic fibrosis transmembrane conductance regulator (CFTR) is an apical membrane anion channel that is widely expressed in epithelia throughout the body. In the airways, CFTR plays an important role in fluid homeostasis and helps flush mucus and inhaled pathogens/toxicants out of the lung. Inhibition of CFTR leads to mucus stasis and severe airway disease. CS exposure also inhibits CFTR, leading to the decreased anion secretion/hydration seen in COPD patients. However, the underlying mechanism is poorly understood. Here, we report that CS causes CFTR to be internalized in a clathrin/dynamin-dependent fashion. This internalization is followed by retrograde trafficking of CFTR to the endoplasmic reticulum. Although this internalization pathway has been described for bacterial toxins and cargo machinery, it has never been reported for mammalian ion channels. Furthermore, the rapid internalization of CFTR is dependent on CFTR dephosphorylation by calcineurin, a protein phosphatase that is upregulated by CS. These results provide new insights into the mechanism of CFTR internalization, and may help in the development of new therapies for CFTR correction and lung rehydration in patients with debilitating airway diseases such as COPD.
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Affiliation(s)
- Abigail J Marklew
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne, UK
| | - Waseema Patel
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne, UK
| | - Patrick J Moore
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA
| | - Chong D Tan
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA
| | - Amanda J Smith
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, USA
| | - M Flori Sassano
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA
| | - Michael A Gray
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne, UK
| | - Robert Tarran
- Marsico Lung Institute, University of North Carolina, Chapel Hill, NC, USA.
- Department of Cell Biology & Physiology, University of North Carolina, Chapel Hill, NC, USA.
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8
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Chothe PP, Czuba LC, Ayewoh EN, Swaan PW. Tyrosine Phosphorylation Regulates Plasma Membrane Expression and Stability of the Human Bile Acid Transporter ASBT (SLC10A2). Mol Pharm 2019; 16:3569-3576. [DOI: 10.1021/acs.molpharmaceut.9b00426] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Paresh P. Chothe
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, United States
| | - Lindsay C. Czuba
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, United States
| | - Ebehiremen N. Ayewoh
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, United States
| | - Peter W. Swaan
- Department of Pharmaceutical Sciences, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, United States
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9
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Abu-Arish A, Pandžić E, Kim D, Tseng HW, Wiseman PW, Hanrahan JW. Agonists that stimulate secretion promote the recruitment of CFTR into membrane lipid microdomains. J Gen Physiol 2019; 151:834-849. [PMID: 31048413 PMCID: PMC6572005 DOI: 10.1085/jgp.201812143] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 04/05/2019] [Indexed: 01/20/2023] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a tightly regulated anion channel that mediates secretion by epithelia and is mutated in the disease cystic fibrosis. CFTR forms macromolecular complexes with many proteins; however, little is known regarding its associations with membrane lipids or the regulation of its distribution and mobility at the cell surface. We report here that secretagogues (agonists that stimulate secretion) such as the peptide hormone vasoactive intestinal peptide (VIP) and muscarinic agonist carbachol increase CFTR aggregation into cholesterol-dependent clusters, reduce CFTR lateral mobility within and between membrane microdomains, and trigger the fusion of clusters into large (3.0 µm2) ceramide-rich platforms. CFTR clusters are closely associated with motile cilia and with the enzyme acid sphingomyelinase (ASMase) that is constitutively bound on the cell surface. Platform induction is prevented by pretreating cells with cholesterol oxidase to disrupt lipid rafts or by exposure to the ASMase functional inhibitor amitriptyline or the membrane-impermeant reducing agent 2-mercaptoethanesulfonate. Platforms are reversible, and their induction does not lead to an increase in apoptosis; however, blocking platform formation does prevent the increase in CFTR surface expression that normally occurs during VIP stimulation. These results demonstrate that CFTR is colocalized with motile cilia and reveal surprisingly robust regulation of CFTR distribution and lateral mobility, most likely through autocrine redox activation of extracellular ASMase. Formation of ceramide-rich platforms containing CFTR enhances transepithelial secretion and likely has other functions related to inflammation and mucosal immunity.
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Affiliation(s)
- Asmahan Abu-Arish
- Department of Physiology, McGill University, Montréal, Canada
- Department of Physics, McGill University, Montréal, Canada
- Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Canada
| | - Elvis Pandžić
- Department of Physics, McGill University, Montréal, Canada
| | - Dusik Kim
- Department of Physiology, McGill University, Montréal, Canada
- Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Canada
| | - Hsin Wei Tseng
- Department of Physiology, McGill University, Montréal, Canada
| | - Paul W Wiseman
- Department of Physics, McGill University, Montréal, Canada
- Department of Chemistry, McGill University, Montréal, Canada
- Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Canada
| | - John W Hanrahan
- Department of Physiology, McGill University, Montréal, Canada
- Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Canada
- McGill University Health Centre Research Institute, Montréal, Canada
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10
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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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11
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Madácsy T, Pallagi P, Maleth J. Cystic Fibrosis of the Pancreas: The Role of CFTR Channel in the Regulation of Intracellular Ca 2+ Signaling and Mitochondrial Function in the Exocrine Pancreas. Front Physiol 2018; 9:1585. [PMID: 30618777 PMCID: PMC6306458 DOI: 10.3389/fphys.2018.01585] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/23/2018] [Indexed: 12/26/2022] Open
Abstract
Cystic fibrosis (CF) is the most common genetic disorder that causes a significant damage in secretory epithelial cells due to the defective ion flux across the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. Pancreas is one of the organs most frequently damaged by the disease leading to pancreatic insufficiency, abdominal pain and an increased risk of acute pancreatitis in CF patients causing a significant decrease in the quality of life. CFTR plays a central role in the pancreatic ductal secretory functions by carrying Cl- and HCO3 - ions across the apical membrane. Therefore pathophysiological studies in CF mostly focused on the effects of impaired ion secretion by pancreatic ductal epithelial cells leading to exocrine pancreatic damage. However, several studies indicated that CFTR has a central role in the regulation of intracellular signaling processes and is now more widely considered as a signaling hub in epithelial cells. In contrast, elevated intracellular Ca2+ level was observed in the lack of functional CFTR in different cell types including airway epithelial cells. In addition, impaired CFTR expression has been correlated with damaged mitochondrial function in epithelial cells. These alterations of intracellular signaling in CF are not well characterized in the exocrine pancreas yet. Therefore in this review we would like to summarize the complex role of CFTR in the exocrine pancreas with a special focus on the intracellular signaling and mitochondrial function.
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Affiliation(s)
- Tamara Madácsy
- First Department of Medicine, University of Szeged, Szeged, Hungary.,HAS-USZ Momentum Epithel Cell Signalling and Secretion Research Group, Szeged, Hungary
| | - Petra Pallagi
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Jozsef Maleth
- First Department of Medicine, University of Szeged, Szeged, Hungary.,HAS-USZ Momentum Epithel Cell Signalling and Secretion Research Group, Szeged, Hungary.,Department of Public Health, University of Szeged, Szeged, Hungary
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12
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Sweat rate analysis of ivacaftor potentiation of CFTR in non-CF adults. Sci Rep 2018; 8:16233. [PMID: 30389955 PMCID: PMC6214959 DOI: 10.1038/s41598-018-34308-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/15/2018] [Indexed: 12/14/2022] Open
Abstract
To determine if ivacaftor (Kalydeco) influences non-CF human CFTR function in vivo, we measured CFTR-dependent (C-sweat) and CFTR-independent (M-sweat) rates from multiple identified sweat glands in 8 non-CF adults. The two types of sweating were stimulated sequentially with intradermal injections of appropriate reagents; each gland served as its own control via alternating off-on drug tests on both arms, given at weekly intervals with 3 off and 3 on tests per subject. We compared drug effects on C-sweating stimulated by either high or low concentrations of β-adrenergic cocktail, and on methacholine-stimulated M-sweating. For each subject we measured ~700 sweat volumes from ~75 glands per arm (maximum 12 readings per gland), and sweat volumes were log-transformed for statistical analysis. T-tests derived from linear mixed models (LMMs) were more conservative than the familiar paired sample t-tests, and show that ivacaftor significantly increased C-sweating stimulated by both levels of agonist, with a larger effect in the low cocktail condition; ivacaftor did not increase M-sweat. Concurrent sweat chloride tests detected no effect of ivacaftor. We conclude that ivacaftor in vivo increases the open channel probability (PO) of WT CFTR, provided it is not already maximally stimulated.
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13
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Lérias J, Pinto M, Benedetto R, Schreiber R, Amaral M, Aureli M, Kunzelmann K. Compartmentalized crosstalk of CFTR and TMEM16A (ANO1) through EPAC1 and ADCY1. Cell Signal 2018; 44:10-19. [PMID: 29331508 DOI: 10.1016/j.cellsig.2018.01.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 12/11/2017] [Accepted: 01/08/2018] [Indexed: 02/08/2023]
Abstract
Airway epithelial cells express both Ca2+ activated TMEM16A/ANO1 and cAMP activated CFTR anion channels. Previous work suggested a significant crosstalk of intracellular Ca2+ and cAMP signaling pathways, leading to activation of both chloride channels. We demonstrate that in airway epithelial cells, stimulation of purinergic or muscarinic G-protein coupled receptors (GPCRs) activates TMEM16A and CFTR. Additional expression of Gq/11 and phospholipase C coupled GPCRs strongly enhanced the crosstalk between Ca2+- and cAMP-dependent signaling. Knockdown of endogenous GRCRs attenuated crosstalk and functional coupling between TMEM16A and CFTR. The number of receptors did not affect expression or membrane localization of TMEM16A or CFTR, but controlled assembly of the local signalosome. GPCRs translocate Ca2+-sensitive adenylate cyclase type 1 (ADCY1) and exchange protein directly activated by cAMP (EPAC1) to particular plasma membrane domains containing GPCRs, CFTR and TMEM16A, thereby producing compartmentalized Ca2+ and cAMP signals and significant crosstalk. While biosynthesis and membrane trafficking of CFTR requires a functional Golgi apparatus, maturation and membrane trafficking of TMEM16A may occur independent of the Golgi. Because Ca2+ activated TMEM16A currents are only transient, continuous Cl- secretion by airway epithelial cells requires CFTR. The present data also explain why receptor-dependent activation of TMEM16A is more efficient than direct stimulation by Ca2+.
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Affiliation(s)
- Joana Lérias
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Madalena Pinto
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Roberta Benedetto
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Margarida Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Massimo Aureli
- Department of Medical Biotechnology and Translational Medicine, University of Milano, Milano, Italy
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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14
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Puglia M, Landi C, Gagliardi A, Breslin L, Armini A, Brunetti J, Pini A, Bianchi L, Bini L. The proteome speciation of an immortalized cystic fibrosis cell line: New perspectives on the pathophysiology of the disease. J Proteomics 2018; 170:28-42. [DOI: 10.1016/j.jprot.2017.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/01/2017] [Accepted: 09/25/2017] [Indexed: 01/04/2023]
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15
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Benedetto R, Ousingsawat J, Wanitchakool P, Zhang Y, Holtzman MJ, Amaral M, Rock JR, Schreiber R, Kunzelmann K. Epithelial Chloride Transport by CFTR Requires TMEM16A. Sci Rep 2017; 7:12397. [PMID: 28963502 PMCID: PMC5622110 DOI: 10.1038/s41598-017-10910-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/16/2017] [Indexed: 12/15/2022] Open
Abstract
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is the secretory chloride/bicarbonate channel in airways and intestine that is activated through ATP binding and phosphorylation by protein kinase A, but fails to operate in cystic fibrosis (CF). TMEM16A (also known as anoctamin 1, ANO1) is thought to function as the Ca2+ activated secretory chloride channel independent of CFTR. Here we report that tissue specific knockout of the TMEM16A gene in mouse intestine and airways not only eliminates Ca2+-activated Cl− currents, but unexpectedly also abrogates CFTR-mediated Cl− secretion and completely abolishes cAMP-activated whole cell currents. The data demonstrate fundamentally new roles of TMEM16A in differentiated epithelial cells: TMEM16A provides a mechanism for enhanced ER Ca2+ store release, possibly engaging Store Operated cAMP Signaling (SOcAMPS) and activating Ca2+ regulated adenylyl cyclases. TMEM16A is shown to be essential for proper activation and membrane expression of CFTR. This intimate regulatory relationship is the cause for the functional overlap of CFTR and Ca2+-dependent chloride transport.
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Affiliation(s)
- Roberta Benedetto
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Podchanart Wanitchakool
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Yong Zhang
- Department of Medicine and Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J Holtzman
- Department of Medicine and Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Margarida Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016, Lisboa, Portugal
| | - Jason R Rock
- Department of Anatomy, University of California, San Francisco, USA
| | - Rainer Schreiber
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Karl Kunzelmann
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany.
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Char JE, Dunn C, Davies Z, Milla C, Moss RB, Wine JJ. The magnitude of ivacaftor effects on fluid secretion via R117H-CFTR channels: Human in vivo measurements. PLoS One 2017; 12:e0175486. [PMID: 28419121 PMCID: PMC5395152 DOI: 10.1371/journal.pone.0175486] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 03/27/2017] [Indexed: 12/20/2022] Open
Abstract
We optically measured effects of orally available ivacaftor (Kalydeco®) on sweat rates of identified glands in 3 R117H subjects, each having a unique set of additional mutations, and compared them with 5 healthy control subjects tested contemporaneously. We injected β-adrenergic agonists intradermally to stimulate CFTR-dependent 'C-sweat' and methacholine to stimulate 'M-sweat', which persists in CF subjects. We focused on an R117H-7T/F508del subject who produced quantifiable C-sweat off ivacaftor and was available for 1 blinded, 3 off ivacaftor, and 3 on ivacaftor tests, allowing us to estimate in vivo fold-increase in sweat rates produced by ivacaftor's effect on the open probability (PO) of R117H-CFTR. Measured sweat rates must be corrected for sweat losses. With estimated sweat losses of 0.023 to 0.08 nl·gland-1·min-1, ivacaftor increased the average C-sweat rates 3-7 fold, and estimated function as % of WT were 4.1-12% off ivacaftor and 21.9-32% on ivacaftor (larger values reflect increased loss estimates). Based on single tests, an R117H-7T/ R117H-7T subject showed 6-9% WT function off ivacaftor and 28-43% on ivacaftor. Repeat testing of an R117H-5T/F508del subject detected only trace responding to ivacaftor. We conclude that in vivo, R117H PO is strongly increased by ivacaftor, but channel number, mainly determined by variable deletion of exon 10, has a marked influence on outcomes.
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Affiliation(s)
- Jessica E. Char
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Colleen Dunn
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Zoe Davies
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Carlos Milla
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Richard B. Moss
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jeffrey J. Wine
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
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17
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Abstract
Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes a chloride channel located in the apical membrane of epithelia cells. The cAMP signaling pathway and protein phosphorylation are known to be primary controlling mechanisms for channel function. In this study, we present an alternative activation pathway that involves calcium-activated calmodulin binding of the intrinsically disordered regulatory (R) region of CFTR. Beyond their potential therapeutic value, these data provide insights into the intersection of calcium signaling with control of ion homeostasis and the ways in which the local CFTR microdomain organizes itself. Cystic fibrosis results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, leading to defective apical chloride transport. Patients also experience overactivation of inflammatory processes, including increased calcium signaling. Many investigations have described indirect effects of calcium signaling on CFTR or other calcium-activated chloride channels; here, we investigate the direct response of CFTR to calmodulin-mediated calcium signaling. We characterize an interaction between the regulatory region of CFTR and calmodulin, the major calcium signaling molecule, and report protein kinase A (PKA)-independent CFTR activation by calmodulin. We describe the competition between calmodulin binding and PKA phosphorylation and the differential effects of this competition for wild-type CFTR and the major F508del mutant, hinting at potential therapeutic strategies. Evidence of CFTR binding to isolated calmodulin domains/lobes suggests a mechanism for the role of CFTR as a molecular hub. Together, these data provide insights into how loss of active CFTR at the membrane can have additional consequences besides impaired chloride transport.
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18
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Marked increases in mucociliary clearance produced by synergistic secretory agonists or inhibition of the epithelial sodium channel. Sci Rep 2016; 6:36806. [PMID: 27830759 PMCID: PMC5103292 DOI: 10.1038/srep36806] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 10/21/2016] [Indexed: 12/11/2022] Open
Abstract
Mucociliary clearance (MCC) is a critical host innate defense mechanism in airways, and it is impaired in cystic fibrosis (CF) and other obstructive lung diseases. Epithelial fluid secretion and absorption modify MCC velocity (MCCV). We tested the hypotheses that inhibiting fluid absorption accelerates MCCV, whereas inhibiting fluid secretion decelerates it. In airways, ENaC is mainly responsible for fluid absorption, while anion channels, including CFTR and Ca2+-activated chloride channels mediate anion/fluid secretion. MCCV was increased by the cAMP-elevating agonists, forskolin or isoproterenol (10 μM) and by the Ca2+-elevating agonist, carbachol (0.3 μM). The CFTR-selective inhibitor, CFTRinh-172, modestly reduced MCCV-increases induced by forskolin or isoproterenol but not increases induced by carbachol. The ENaC inhibitor benzamil increased basal MCCV as well as MCCV increases produced by forskolin or carbachol. MCC velocity was most dramatically accelerated by the synergistic combination of forskolin and carbachol, which produced near-maximal clearance rates regardless of prior treatment with CFTR or ENaC inhibitors. In CF airways, where CFTR-mediated secretion (and possibly synergistic MCC) is lost, ENaC inhibition via exogenous agents may provide therapeutic benefit, as has long been proposed.
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19
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c- Src and its role in cystic fibrosis. Eur J Cell Biol 2016; 95:401-413. [DOI: 10.1016/j.ejcb.2016.08.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/08/2016] [Accepted: 08/10/2016] [Indexed: 12/15/2022] Open
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Billet A, Jia Y, Jensen TJ, Hou YX, Chang XB, Riordan JR, Hanrahan JW. Potential sites of CFTR activation by tyrosine kinases. Channels (Austin) 2015; 10:247-51. [PMID: 26645934 DOI: 10.1080/19336950.2015.1126010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The CFTR chloride channel is tightly regulated by phosphorylation at multiple serine residues. Recently it has been proposed that its activity is also regulated by tyrosine kinases, however the tyrosine phosphorylation sites remain to be identified. In this study we examined 2 candidate tyrosine residues near the boundary between the first nucleotide binding domain and the R domain, a region which is important for channel function but devoid of PKA consensus sequences. Mutating tyrosines at positions 625 and 627 dramatically reduced responses to Src or Pyk2 without altering the activation by PKA, suggesting they may contribute to CFTR regulation.
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Affiliation(s)
- Arnaud Billet
- a Department of Physiology , McGill University , Montreal , Quebec , Canada.,b CF Translational Research Center, McGill University , Montreal , Quebec , Canada
| | - Yanlin Jia
- a Department of Physiology , McGill University , Montreal , Quebec , Canada.,b CF Translational Research Center, McGill University , Montreal , Quebec , Canada
| | - Timothy J Jensen
- c Department of Biochemistry and Biophysics & CF Research Center , UNC Chapel Hill, Chapel Hill , NC , USA
| | - Yue-Xian Hou
- c Department of Biochemistry and Biophysics & CF Research Center , UNC Chapel Hill, Chapel Hill , NC , USA
| | - Xiu-Bao Chang
- c Department of Biochemistry and Biophysics & CF Research Center , UNC Chapel Hill, Chapel Hill , NC , USA
| | - John R Riordan
- c Department of Biochemistry and Biophysics & CF Research Center , UNC Chapel Hill, Chapel Hill , NC , USA
| | - John W Hanrahan
- a Department of Physiology , McGill University , Montreal , Quebec , Canada.,b CF Translational Research Center, McGill University , Montreal , Quebec , Canada.,d Research Institute of the McGill University Hospital Center , Montréal , Quebec , Canada
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21
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Dittrich NP, Kummer W, Clauss WG, Fronius M. Luminal acetylcholine does not affect the activity of the CFTR in tracheal epithelia of pigs. Int Immunopharmacol 2015; 29:166-72. [DOI: 10.1016/j.intimp.2015.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 11/29/2022]
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22
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Namkoong E, Shin YH, Bae JS, Choi S, Kim M, Kim N, Hwang SM, Park K. Role of Sodium Bicarbonate Cotransporters in Intracellular pH Regulation and Their Regulatory Mechanisms in Human Submandibular Glands. PLoS One 2015; 10:e0138368. [PMID: 26375462 PMCID: PMC4573515 DOI: 10.1371/journal.pone.0138368] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/28/2015] [Indexed: 01/16/2023] Open
Abstract
Sodium bicarbonate cotransporters (NBCs) are involved in the pH regulation of salivary glands. However, the roles and regulatory mechanisms among different NBC isotypes have not been rigorously evaluated. We investigated the roles of two different types of NBCs, electroneutral (NBCn1) and electrogenic NBC (NBCe1), with respect to pH regulation and regulatory mechanisms using human submandibular glands (hSMGs) and HSG cells. Intracellular pH (pHi) was measured and the pHi recovery rate from cell acidification induced by an NH4Cl pulse was recorded. Subcellular localization and protein phosphorylation were determined using immunohistochemistry and co-immunoprecipitation techniques. We determined that NBCn1 is expressed on the basolateral side of acinar cells and the apical side of duct cells, while NBCe1 is exclusively expressed on the apical membrane of duct cells. The pHi recovery rate in hSMG acinar cells, which only express NBCn1, was not affected by pre-incubation with 5 μM PP2, an Src tyrosine kinase inhibitor. However, in HSG cells, which express both NBCe1 and NBCn1, the pHi recovery rate was inhibited by PP2. The apparent difference in regulatory mechanisms for NBCn1 and NBCe1 was evaluated by artificial overexpression of NBCn1 or NBCe1 in HSG cells, which revealed that the pHi recovery rate was only inhibited by PP2 in cells overexpressing NBCe1. Furthermore, only NBCe1 was significantly phosphorylated and translocated by NH4Cl, which was inhibited by PP2. Our results suggest that both NBCn1 and NBCe1 play a role in pHi regulation in hSMG acinar cells, and also that Src kinase does not regulate the activity of NBCn1.
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Affiliation(s)
- Eun Namkoong
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Yong-Hwan Shin
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Jun-Seok Bae
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Seulki Choi
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Minkyoung Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Nahyun Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Sung-Min Hwang
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Kyungpyo Park
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
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23
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Billet A, Jia Y, Jensen T, Riordan JR, Hanrahan JW. Regulation of the cystic fibrosis transmembrane conductance regulator anion channel by tyrosine phosphorylation. FASEB J 2015; 29:3945-53. [PMID: 26062600 DOI: 10.1096/fj.15-273151] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/26/2015] [Indexed: 11/11/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) channel is activated by PKA phosphorylation of a regulatory domain that interacts dynamically with multiple CFTR domains and with other proteins. The large number of consensus sequences for phosphorylation by PKA has naturally focused most attention on regulation by this kinase. We report here that human CFTR is also phosphorylated by the tyrosine kinases p60c-Src (proto-oncogene tyrosine-protein kinase) and the proline-rich tyrosine kinase 2 (Pyk2), and they can also cause robust activation of quiescent CFTR channels. In excised patch-clamp experiments, CFTR activity during exposure to Src or Pyk2 reached ∼80% of that stimulated by PKA. Exposure to PKA after Src or Pyk2 caused a further increase to the level induced by PKA alone, implying a common limiting step. Channels became spontaneously active when v-Src or the catalytic domain of Pyk2 was coexpressed with CFTR and were further stimulated by the tyrosine phosphatase inhibitor dephostatin. Exogenous Src also activated 15SA-CFTR, a variant that lacks 15 potential PKA sites and has little response to PKA. PKA-independent activation by tyrosine phosphorylation has implications for the mechanism of regulation by the R domain and for the physiologic functions of CFTR.
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Affiliation(s)
- Arnaud Billet
- *Department of Physiology and Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada; Department of Biochemistry and Biophysics and Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA; and Research Institute of the McGill University Hospital Centre, Montreal, Quebec, Canada
| | - Yanlin Jia
- *Department of Physiology and Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada; Department of Biochemistry and Biophysics and Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA; and Research Institute of the McGill University Hospital Centre, Montreal, Quebec, Canada
| | - Tim Jensen
- *Department of Physiology and Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada; Department of Biochemistry and Biophysics and Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA; and Research Institute of the McGill University Hospital Centre, Montreal, Quebec, Canada
| | - John R Riordan
- *Department of Physiology and Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada; Department of Biochemistry and Biophysics and Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA; and Research Institute of the McGill University Hospital Centre, Montreal, Quebec, Canada
| | - John W Hanrahan
- *Department of Physiology and Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada; Department of Biochemistry and Biophysics and Cystic Fibrosis Research Center, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina, USA; and Research Institute of the McGill University Hospital Centre, Montreal, Quebec, Canada
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24
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Ivonnet P, Salathe M, Conner GE. Hydrogen peroxide stimulation of CFTR reveals an Epac-mediated, soluble AC-dependent cAMP amplification pathway common to GPCR signalling. Br J Pharmacol 2014; 172:173-84. [PMID: 25220136 DOI: 10.1111/bph.12934] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/27/2014] [Accepted: 09/03/2014] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE H2 O2 is widely understood to regulate intracellular signalling. In airway epithelia, H2 O2 stimulates anion secretion primarily by activating an autocrine PGE2 signalling pathway via EP4 and EP1 receptors to initiate cytic fibrosis transmembrane regulator (CFTR)-mediated Cl(-) secretion. This study investigated signalling downstream of the receptors activated by H2 O2 . EXPERIMENTAL APPROACH Anion secretion by differentiated bronchial epithelial cells was measured in Ussing chambers during stimulation with H2 O2 , an EP4 receptor agonist or β2 -adrenoceptor agonist in the presence and absence of inhibitors of ACs and downstream effectors. Intracellular calcium ([Ca(2+) ]I ) changes were followed by microscopy using fura-2-loaded cells and PKA activation followed by FRET microscopy. KEY RESULTS Transmembrane adenylyl cyclase (tmAC) and soluble AC (sAC) were both necessary for H2 O2 and EP4 receptor-mediated CFTR activation in bronchial epithelia. H2 O2 and EP4 receptor agonist stimulated tmAC to increase exchange protein activated by cAMP (Epac) activity that drives PLC activation to raise [Ca(2+) ]i via Ca(2+) store release (and not entry). Increased [Ca(2+) ]i led to sAC activation and further increases in CFTR activity. Stimulation of sAC did not depend on changes in [HCO3 (-) ]. Ca(2+) -activated apical KCa 1.1 channels and cAMP-activated basolateral KV 7.1 channels contributed to H2 O2 -stimulated anion currents. A similar Epac-mediated pathway was seen following β2 -adrenoceptor or forskolin stimulation. CONCLUSIONS AND IMPLICATIONS H2 O2 initiated a complex signalling cascade that used direct stimulation of tmACs by Gαs followed by Epac-mediated Ca(2+) crosstalk to activate sAC. The Epac-mediated Ca(2+) signal constituted a positive feedback loop that amplified CFTR anion secretion following stimulation of tmAC by a variety of stimuli.
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Affiliation(s)
- P Ivonnet
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami, Miami, Florida, USA
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25
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Char JE, Wolfe MH, Cho HJ, Park IH, Jeong JH, Frisbee E, Dunn C, Davies Z, Milla C, Moss RB, Thomas EAC, Wine JJ. A little CFTR goes a long way: CFTR-dependent sweat secretion from G551D and R117H-5T cystic fibrosis subjects taking ivacaftor. PLoS One 2014; 9:e88564. [PMID: 24520399 PMCID: PMC3919757 DOI: 10.1371/journal.pone.0088564] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 01/12/2014] [Indexed: 01/02/2023] Open
Abstract
To determine if oral dosing with the CFTR-potentiator ivacaftor (VX-770, Kalydeco) improves CFTR-dependent sweating in CF subjects carrying G551D or R117H-5T mutations, we optically measured sweat secretion from 32-143 individually identified glands in each of 8 CF subjects; 6 F508del/G551D, one G551D/R117H-5T, and one I507del/R117H-5T. Two subjects were tested only (-) ivacaftor, 3 only (+) ivacaftor and 3 (+/-) ivacaftor (1-5 tests per condition). The total number of gland measurements was 852 (-) ivacaftor and 906 (+) ivacaftor. A healthy control was tested 4 times (51 glands). For each gland we measured both CFTR-independent (M-sweat) and CFTR-dependent (C-sweat); C-sweat was stimulated with a β-adrenergic cocktail that elevated [cAMP]i while blocking muscarinic receptors. Absent ivacaftor, almost all CF glands produced M-sweat on all tests, but only 1/593 glands produced C-sweat (10 tests, 5 subjects). By contrast, 6/6 subjects (113/342 glands) produced C-sweat in the (+) ivacaftor condition, but with large inter-subject differences; 3-74% of glands responded with C/M sweat ratios 0.04%-2.57% of the average WT ratio of 0.265. Sweat volume losses cause proportionally larger underestimates of CFTR function at lower sweat rates. The losses were reduced by measuring C/M ratios in 12 glands from each subject that had the highest M-sweat rates. Remaining losses were estimated from single channel data and used to correct the C/M ratios, giving estimates of CFTR function (+) ivacaftor = 1.6%-7.7% of the WT average. These estimates are in accord with single channel data and transcript analysis, and suggest that significant clinical benefit can be produced by low levels of CFTR function.
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Affiliation(s)
- Jessica E. Char
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Marlene H. Wolfe
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Hyung-ju Cho
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Il-Ho Park
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Jin Hyeok Jeong
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Eric Frisbee
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
| | - Colleen Dunn
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Zoe Davies
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Carlos Milla
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Richard B. Moss
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Ewart A. C. Thomas
- Department of Psychology, Stanford University, Stanford, California, United States of America
| | - Jeffrey J. Wine
- Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California, United States of America
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Psychology, Stanford University, Stanford, California, United States of America
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26
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Novak I, Haanes KA, Wang J. Acid-base transport in pancreas-new challenges. Front Physiol 2013; 4:380. [PMID: 24391597 PMCID: PMC3868914 DOI: 10.3389/fphys.2013.00380] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/04/2013] [Indexed: 12/11/2022] Open
Abstract
Along the gastrointestinal tract a number of epithelia contribute with acid or basic secretions in order to aid digestive processes. The stomach and pancreas are the most extreme examples of acid (H(+)) and base (HCO(-) 3) transporters, respectively. Nevertheless, they share the same challenges of transporting acid and bases across epithelia and effectively regulating their intracellular pH. In this review, we will make use of comparative physiology to enlighten the cellular mechanisms of pancreatic HCO(-) 3 and fluid secretion, which is still challenging physiologists. Some of the novel transporters to consider in pancreas are the proton pumps (H(+)-K(+)-ATPases), as well as the calcium-activated K(+) and Cl(-) channels, such as KCa3.1 and TMEM16A/ANO1. Local regulators, such as purinergic signaling, fine-tune, and coordinate pancreatic secretion. Lastly, we speculate whether dys-regulation of acid-base transport contributes to pancreatic diseases including cystic fibrosis, pancreatitis, and cancer.
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Affiliation(s)
- Ivana Novak
- Department of Biology, University of Copenhagen Copenhagen, Denmark
| | | | - Jing Wang
- Department of Biology, University of Copenhagen Copenhagen, Denmark
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Billet A, Hanrahan JW. The secret life of CFTR as a calcium-activated chloride channel. J Physiol 2013; 591:5273-8. [PMID: 23959675 PMCID: PMC3936366 DOI: 10.1113/jphysiol.2013.261909] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/15/2013] [Indexed: 12/27/2022] Open
Abstract
cAMP-stimulated anion conductance is defective in cystic fibrosis (CF). The regulatory domain of CFTR, the anion channel protein encoded by the CF gene, possesses an unusually high density of consensus sequences for phosphorylation by protein kinase A (14 in a stretch of <200 amino acids). Thus it is not surprising that CFTR is viewed primarily as a cAMP-stimulated anion channel, and most studies have focused on this mode of activation. However, there is growing evidence that CFTR also responds to Ca(2+)-mobilizing secretagogues and contributes substantially to cholinergic and purinergic responses in native tissues. G protein-coupled receptors that signal through Gαq can stimulate CFTR channels by activating Ca(2+)-dependent adenylyl cyclase and tyrosine kinases, and also by inhibiting protein phosphatase type 2A. Here we review evidence for these novel mechanisms of CFTR activation and discuss how they may help explain previous observations.
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Affiliation(s)
- Arnaud Billet
- J. W. Hanrahan: Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, Canada H3G 1Y6.
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Phosphorylation of cystic fibrosis transmembrane conductance regulator (CFTR) serine-511 by the combined action of tyrosine kinases and CK2: the implication of tyrosine-512 and phenylalanine-508. Amino Acids 2013; 45:1423-9. [DOI: 10.1007/s00726-013-1613-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 10/19/2013] [Indexed: 12/22/2022]
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