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Dębczyński M, Gorrieri G, Mojsak D, Guida F, Zara F, Scudieri P. ATP12A Proton Pump as an Emerging Therapeutic Target in Cystic Fibrosis and Other Respiratory Diseases. Biomolecules 2023; 13:1455. [PMID: 37892136 PMCID: PMC10605105 DOI: 10.3390/biom13101455] [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: 08/30/2023] [Revised: 09/15/2023] [Accepted: 09/25/2023] [Indexed: 10/29/2023] Open
Abstract
ATP12A encodes the catalytic subunit of the non-gastric proton pump, which is expressed in many epithelial tissues and mediates the secretion of protons in exchange for potassium ions. In the airways, ATP12A-dependent proton secretion contributes to complex mechanisms regulating the composition and properties of the fluid and mucus lining the respiratory epithelia, which are essential to maintain the airway host defense and the respiratory health. Increased expression and activity of ATP12A in combination with the loss of other balancing activities, such as the bicarbonate secretion mediated by CFTR, leads to excessive acidification of the airway surface liquid and mucus dysfunction, processes that play relevant roles in the pathogenesis of cystic fibrosis and other chronic inflammatory respiratory disorders. In this review, we summarize the findings dealing with ATP12A expression, function, and modulation in the airways, which led to the consideration of ATP12A as a potential therapeutic target for the treatment of cystic fibrosis and other airway diseases; we also highlight the current advances and gaps regarding the development of therapeutic strategies aimed at ATP12A inhibition.
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Affiliation(s)
- Michał Dębczyński
- 2nd Department of Lung Diseases and Tuberculosis, Medical University of Bialystok, 15-540 Bialystok, Poland; (M.D.); (D.M.)
| | - Giulia Gorrieri
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, 16132 Genoa, Italy; (G.G.); (F.G.); (F.Z.)
| | - Damian Mojsak
- 2nd Department of Lung Diseases and Tuberculosis, Medical University of Bialystok, 15-540 Bialystok, Poland; (M.D.); (D.M.)
| | - Floriana Guida
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, 16132 Genoa, Italy; (G.G.); (F.G.); (F.Z.)
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, 16132 Genoa, Italy; (G.G.); (F.G.); (F.Z.)
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Paolo Scudieri
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, 16132 Genoa, Italy; (G.G.); (F.G.); (F.Z.)
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
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2
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Wang Z, Pan T, Shen M, Liao J, Tian Y. Cross-conjugated polymers as fluorescent probes for intracellular potassium ion detection. SENSORS AND ACTUATORS B: CHEMICAL 2023; 390:134008. [DOI: 10.1016/j.snb.2023.134008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
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3
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Amaral MD. Using the genome to correct the ion transport defect in cystic fibrosis. J Physiol 2022; 601:1573-1582. [PMID: 36068724 DOI: 10.1113/jp282308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 08/31/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Human genome information can help finding drugs for human diseases. 'Omics' allow unbiased identification of novel drug targets. High-throughput (HT) approaches provide a global view on disease mechanisms. As a monogenic disease CF has led the way in multiple 'Omic' studies. 'Multi-omics' integration will generate maximal biological significance. ABSTRACT Today Biomedicine faces one of its greatest challenges, i.e. treating diseases through their causative dysfunctional processes and not just their symptoms. However, we still miss a global view of mechanisms and pathways involved in pathophysiology of most diseases. In fact, disease mechanisms and pathways can be achieved by holistic studies provided by 'Omic' approaches. Cystic Fibrosis (CF), caused by mutations in the CF transmembrane conductance regulator (CFTR) gene which encodes an anion channel, is paradigmatic for monogenic disorders, namely channelopathies. A high number of 'omics studies' have focussed on CF, namely several cell-based high-throughput (HT) approaches were developed and applied towards a global mechanistic characterization of CF pathophysiology and the identification of novel and 'unbiased' drug targets. Notwithstanding, it is likely that, through the integration of all these 'layers' of large datasets into comprehensive disease maps that biological significance can be extracted so that the enormous potential of these approaches to identifying dysfunctional mechanisms and novel drugs may become a reality. Abstract figure legend Schematic overview of the 3 main approaches to discovery of new drugs/drug targets. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Margarida D Amaral
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande-C8 bdg, Lisboa, 1749-016, Portugal
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Boecking CA, Walentek P, Zlock LT, Sun DI, Wolters PJ, Ishikawa H, Jin BJ, Haggie PM, Marshall WF, Verkman AS, Finkbeiner WE. A simple method to generate human airway epithelial organoids with externally orientated apical membranes. Am J Physiol Lung Cell Mol Physiol 2022; 322:L420-L437. [PMID: 35080188 PMCID: PMC8917940 DOI: 10.1152/ajplung.00536.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Organoids, which are self-organizing three-dimensional cultures, provide models that replicate specific cellular components of native tissues or facets of organ complexity. We describe a simple method to generate organoid cultures using isolated human tracheobronchial epithelial cells grown in mixed matrix components and supplemented at day 14 with the Wnt pathway agonist R-spondin 2 (RSPO2) and the bone morphogenic protein antagonist Noggin. In contrast to previous reports, our method produces differentiated tracheobronchospheres with externally orientated apical membranes without pretreatments, providing an epithelial model to study cilia formation and function, disease pathogenesis, and interaction of pathogens with the respiratory mucosa. Starting from 3 × 105 cells, organoid yield at day 28 was 1,720 ± 302. Immunocytochemistry confirmed the cellular localization of airway epithelial markers, including CFTR, Na+/K+ ATPase, acetylated-α-tubulin, E-cadherin, and ZO-1. Compared to native tissues, expression of genes related to bronchial differentiation and ion transport were similar in organoid and air-liquid interface (ALI) cultures. In matched primary cultures, mean organoid cilia length was 6.1 ± 0.2 µm, similar to that of 5.7 ± 0.1 µm in ALI cultures, and ciliary beating was vigorous and coordinated with frequencies of 7.7 ± 0.3 Hz in organoid cultures and 5.3 ± 0.8 Hz in ALI cultures. Functional measurement of osmotically induced volume changes in organoids showed low water permeability. The generation of numerous single testable units from minimal starting material complements prior techniques. This culture system may be useful for studying airway biology and pathophysiology, aiding diagnosis of ciliopathies, and potentially for high-throughput drug screening.
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Affiliation(s)
- Carolin A. Boecking
- 1Department of Pathology, University of California, San Francisco, California
| | - Peter Walentek
- 2Genomics and Development Division, Molecular and Cell Biology Department, University of California, Berkeley, California,3Renal Division, Department of Medicine, University Hospital Freiburg, Freiburg University Faculty of Medicine, Freiburg, Germany,4CIBSS – Centre for Integrative Biological Signalling Studies, Albert Ludwigs University Freiburg, Freiburg, Germany
| | - Lorna T. Zlock
- 1Department of Pathology, University of California, San Francisco, California
| | - Dingyuan I. Sun
- 1Department of Pathology, University of California, San Francisco, California
| | - Paul J. Wolters
- 5Department of Medicine, University of California, San Francisco, California
| | - Hiroaki Ishikawa
- 6Department of Biochemistry and Biophysics, University of California, San Francisco, California
| | - Byung-Ju Jin
- 5Department of Medicine, University of California, San Francisco, California
| | - Peter M. Haggie
- 5Department of Medicine, University of California, San Francisco, California
| | - Wallace F. Marshall
- 6Department of Biochemistry and Biophysics, University of California, San Francisco, California
| | - Alan S. Verkman
- 5Department of Medicine, University of California, San Francisco, California,7Department of Physiology, University of California, San Francisco, California
| | - Walter E. Finkbeiner
- 1Department of Pathology, University of California, San Francisco, California,8Innovative Genomics Institute, University of California, Berkeley, California
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Abstract
Artificial receptors able to recognise biologically relevant molecules or ions have gained interest in the chemical community because they offer a plethora of posibilities. Molecular cage compounds are polycyclic compounds with a cavity designed for the encapsulation of guest species. Once inside the host cavity, the substrate can be transported through membranes and protected from the action of enzymes or other reactive species, thus offering the possibility of interfering with biological systems. Commonly, enzymes have been an inspiration for chemists in the search and design of defined cavities for different purposes. However, the chemical preparation of molecular cages has struggled with many synthetic challenges but this effort is worthwhile as they are a very promising tool for many applications ranging from sensing, delivery, purification or even promotion of/prevention from chemical modifications. Since the early reports at the end of the 60s, this field has experienced a growing interest; this review summarises the progress in the preparation and study of cage-like compounds highlighting their importance in biological applications.
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Affiliation(s)
- Lucía Tapia
- Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
| | - Ignacio Alfonso
- Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
| | - Jordi Solà
- Department of Biological Chemistry, Institute for Advanced Chemistry of Catalonia, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
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Muhanna D, Arnipalli SR, Kumar SB, Ziouzenkova O. Osmotic Adaptation by Na +-Dependent Transporters and ACE2: Correlation with Hemostatic Crisis in COVID-19. Biomedicines 2020; 8:E460. [PMID: 33142989 PMCID: PMC7693583 DOI: 10.3390/biomedicines8110460] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 01/08/2023] Open
Abstract
COVID-19 symptoms, including hypokalemia, hypoalbuminemia, ageusia, neurological dysfunctions, D-dimer production, and multi-organ microthrombosis reach beyond effects attributed to impaired angiotensin-converting enzyme 2 (ACE2) signaling and elevated concentrations of angiotensin II (Ang II). Although both SARS-CoV (Severe Acute Respiratory Syndrome Coronavirus) and SARS-CoV-2 utilize ACE2 for host entry, distinct COVID-19 pathogenesis coincides with the acquisition of a new sequence, which is homologous to the furin cleavage site of the human epithelial Na+ channel (ENaC). This review provides a comprehensive summary of the role of ACE2 in the assembly of Na+-dependent transporters of glucose, imino and neutral amino acids, as well as the functions of ENaC. Data support an osmotic adaptation mechanism in which osmotic and hemostatic instability induced by Ang II-activated ENaC is counterbalanced by an influx of organic osmolytes and Na+ through the ACE2 complex. We propose a paradigm for the two-site attack of SARS-CoV-2 leading to ENaC hyperactivation and inactivation of the ACE2 complex, which collapses cell osmolality and leads to rupture and/or necrotic death of swollen pulmonary, endothelial, and cardiac cells, thrombosis in infected and non-infected tissues, and aberrant sensory and neurological perception in COVID-19 patients. This dual mechanism employed by SARS-CoV-2 calls for combinatorial treatment strategies to address and prevent severe complications of COVID-19.
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Affiliation(s)
| | | | | | - Ouliana Ziouzenkova
- Department of Human Sciences, The Ohio State University, Columbus, OH 43210, USA; (D.M.); (S.R.A.); (S.B.K.)
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Bein K, Ganguly K, Martin TM, Concel VJ, Brant KA, Di YPP, Upadhyay S, Fabisiak JP, Vuga LJ, Kaminski N, Kostem E, Eskin E, Prows DR, Jang AS, Leikauf GD. Genetic determinants of ammonia-induced acute lung injury in mice. Am J Physiol Lung Cell Mol Physiol 2020; 320:L41-L62. [PMID: 33050709 DOI: 10.1152/ajplung.00276.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In this study, a genetically diverse panel of 43 mouse strains was exposed to ammonia, and genome-wide association mapping was performed employing a single-nucleotide polymorphism (SNP) assembly. Transcriptomic analysis was used to help resolve the genetic determinants of ammonia-induced acute lung injury. The encoded proteins were prioritized based on molecular function, nonsynonymous SNP within a functional domain or SNP within the promoter region that altered expression. This integrative functional approach revealed 14 candidate genes that included Aatf, Avil, Cep162, Hrh4, Lama3, Plcb4, and Ube2cbp, which had significant SNP associations, and Aff1, Bcar3, Cntn4, Kcnq5, Prdm10, Ptcd3, and Snx19, which had suggestive SNP associations. Of these genes, Bcar3, Cep162, Hrh4, Kcnq5, and Lama3 are particularly noteworthy and had pathophysiological roles that could be associated with acute lung injury in several ways.
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Affiliation(s)
- Kiflai Bein
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Koustav Ganguly
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.,Unit of Integrated Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Timothy M Martin
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Vincent J Concel
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kelly A Brant
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Y P Peter Di
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Swapna Upadhyay
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.,Unit of Integrated Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - James P Fabisiak
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Louis J Vuga
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.,Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Yale School of Medicine, New Haven, Connecticut
| | - Naftali Kaminski
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.,Department of Medicine, Simmons Center for Interstitial Lung Disease, University of Pittsburgh, Pittsburgh, Pennsylvania.,Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Yale School of Medicine, New Haven, Connecticut
| | - Emrah Kostem
- Departments of Computer Science and Human Genetics, University of California, Los Angeles, California
| | - Eleazar Eskin
- Departments of Computer Science and Human Genetics, University of California, Los Angeles, California
| | - Daniel R Prows
- Division of Human Genetics, Cincinnati Children's Hospital and Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio
| | - Ann-Soo Jang
- Division of Allergy and Respiratory Medicine, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, South Korea
| | - George D Leikauf
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
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8
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Thornell IM, Rehman T, Pezzulo AA, Welsh MJ. Paracellular bicarbonate flux across human cystic fibrosis airway epithelia tempers changes in airway surface liquid pH. J Physiol 2020; 598:4307-4320. [PMID: 32627187 PMCID: PMC7589346 DOI: 10.1113/jp280120] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/22/2020] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Cl- and HCO3- had similar paracellular permeabilities in human airway epithelia. PCl /PNa of airway epithelia was unaltered by pH 7.4 vs. pH 6.0 solutions. Under basal conditions, calculated paracellular HCO3- flux was secretory. Cytokines that increased airway surface liquid pH decreased or reversed paracellular HCO3- flux. HCO3- flux through the paracellular pathway may counterbalance effects of cellular H+ and HCO3- secretion. ABSTRACT Airway epithelia control the pH of airway surface liquid (ASL), thereby optimizing respiratory defences. Active H+ and HCO3- secretion by airway epithelial cells produce an ASL that is acidic compared with the interstitial space. The paracellular pathway could provide a route for passive HCO3- flux that also modifies ASL pH. However, there is limited information about paracellular HCO3- flux, and it remains uncertain whether an acidic pH produced by loss of cystic fibrosis transmembrane conductance regulator anion channels or proinflammatory cytokines might alter the paracellular pathway function. To investigate paracellular HCO3- transport, we studied differentiated primary cultures of human cystic fibrosis (CF) and non-CF airway epithelia. The paracellular pathway was pH-insensitive at pH 6.0 vs. pH 7.4 and was equally permeable to Cl- and HCO3- . Under basal conditions at pH ∼6.6, calculated paracellular HCO3- flux was weakly secretory. Treating epithelia with IL-17 plus TNFα alkalinized ASL pH to ∼7.0, increased paracellular HCO3- permeability, and paracellular HCO3- flux was negligible. Applying IL-13 increased ASL pH to ∼7.4 without altering paracellular HCO3- permeability, and calculated paracellular HCO3- flux was absorptive. These results suggest that HCO3- flux through the paracellular pathway counterbalances, in part, changes in the ASL pH produced via cellular mechanisms. As the pH of ASL increases towards that of basolateral liquid, paracellular HCO3- flux becomes absorptive, tempering the alkaline pH generated by transcellular HCO3- secretion.
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Affiliation(s)
- Ian M. Thornell
- Department of Internal MedicinePappajohn Biomedical InstituteRoy J. and Lucille A. Carver College of MedicineUniversity of IowaIowa CityIAUSA
| | - Tayyab Rehman
- Department of Internal MedicinePappajohn Biomedical InstituteRoy J. and Lucille A. Carver College of MedicineUniversity of IowaIowa CityIAUSA
| | - Alejandro A. Pezzulo
- Department of Internal MedicinePappajohn Biomedical InstituteRoy J. and Lucille A. Carver College of MedicineUniversity of IowaIowa CityIAUSA
| | - Michael J. Welsh
- Department of Internal MedicinePappajohn Biomedical InstituteRoy J. and Lucille A. Carver College of MedicineUniversity of IowaIowa CityIAUSA
- Department of Molecular Physiology and BiophysicsPappajohn Biomedical InstituteRoy J. and Lucille A. Carver College of MedicineUniversity of IowaIowa CityIAUSA
- Howard Hughes Medical InstituteUniversity of IowaIowa CityIAUSA
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9
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Garth J, Easter M, Skylar Harris E, Sailland J, Kuenzi L, Chung S, Dennis JS, Baumlin N, Adewale AT, Rowe SM, King G, Faul C, Barnes JW, Salathe M, Krick S. The Effects of the Anti-aging Protein Klotho on Mucociliary Clearance. Front Med (Lausanne) 2020; 6:339. [PMID: 32039219 PMCID: PMC6992571 DOI: 10.3389/fmed.2019.00339] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/24/2019] [Indexed: 01/23/2023] Open
Abstract
α-klotho (KL) is an anti-aging protein and has been shown to exert anti-inflammatory and anti-oxidative effects in the lung and pulmonary diseases such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis. The current study investigated the direct effect of KL on the bronchial epithelium in regards to mucociliary clearance parameters. Primary human bronchial and murine tracheal epithelial cells, cultured, and differentiated at the air liquid interface (ALI), were treated with recombinant KL or infected with a lentiviral vector expressing KL. Airway surface liquid (ASL) volume, airway ion channel activities, and expression levels were analyzed. These experiments were paired with ex vivo analyses of mucociliary clearance in murine tracheas from klotho deficient mice and their wild type littermates. Our results showed that klotho deficiency led to impaired mucociliary clearance with a reduction in ASL volume in vitro and ex vivo. Overexpression or exogenous KL increased ASL volume, which was paralleled by increased activation of the large-conductance, Ca2+-activated, voltage-dependent potassium channel (BK) without effect on the cystic fibrosis transmembrane conductance regulator (CFTR). Furthermore, KL overexpression downregulated IL-8 levels and attenuated TGF-β-mediated downregulation of LRRC26, the γ subunit of BK, necessary for its function in non-excitable cells. In summary, we show that KL regulates mucociliary function by increasing ASL volume in the airways possibly due to underlying BK activation. The KL mediated BK channel activation may be a potentially important target to design therapeutic strategies in inflammatory airway diseases when ASL volume is decreased.
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Affiliation(s)
- Jaleesa Garth
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Molly Easter
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Elex Skylar Harris
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Juliette Sailland
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Lisa Kuenzi
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Samuel Chung
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - John S. Dennis
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Nathalie Baumlin
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Adegboyega T. Adewale
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Steven M. Rowe
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Gwendalyn King
- Department of Biology, Creighton University, Omaha, NE, United States
| | - Christian Faul
- Division of Nephrology, Department of Medicine, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jarrod W. Barnes
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Matthias Salathe
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine University of Kansas Medical Center, Kansas City, KS, United States
| | - Stefanie Krick
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Gregory Fleming James Cystic Fibrosis Research Center, The University of Alabama at Birmingham, Birmingham, AL, United States
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10
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Delpiano L, Thomas JJ, Yates AR, Rice SJ, Gray MA, Saint-Criq V. Esomeprazole Increases Airway Surface Liquid pH in Primary Cystic Fibrosis Epithelial Cells. Front Pharmacol 2018; 9:1462. [PMID: 30618754 PMCID: PMC6297391 DOI: 10.3389/fphar.2018.01462] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/29/2018] [Indexed: 12/30/2022] Open
Abstract
Respiratory failure, driven by airways mucus obstruction, chronic inflammation and bacterial infections, is the main cause of mortality and morbidity in people with cystic fibrosis (CF) due to defects in the Cl- andHCO 3 - transport activity of the CF Transmembrane conductance Regulator (CFTR). Most recent pre-clinical and clinical studies have focused on restoring CFTR function by enhancing its trafficking or transport activity and show promising results. However, there are a significant number of patients that will not benefit from these CFTR-targeted therapies and it is therefore important to identify new non-CFTR targets that will restore lung function, by-passing CFTR dysfunction. The H+/K+-ATPase, ATP12A, has recently been identified as a potential novel target for CF therapies, since its acute inhibition by ouabain was shown to help restore mucus viscosity, mucociliary transport, and antimicrobial activity using in vitro CF airway models, and this effect was linked to an increase in the pH of the airway surface liquid (ASL). Here, we have evaluated the potential therapeutic use of ouabain by investigating the effect of chronically treating fully differentiated CF primary human airway epithelial cells (hAECs) with ouabain, under thin film conditions, resembling the in vivo situation. Our results show that although chronic treatment increased ASL pH, this correlated with a deleterious effect on epithelial integrity as assessed by LDH release, transepithelial electrical resistance, fluorescein flux, and ion transport. Since ATP12A shares approximately 65% identity with the gastric H+/K+-ATPase (ATP4A), we investigated the potential of using clinically approved ATP4A proton pump inhibitors (PPIs) for their ability to restore ASL pH in CF hAECs. We show that, despite not expressing ATP4A transcripts, acute exposure to the PPI esomeprezole, produced changes in intracellular pH that were consistent with the inhibition of H+ secretion, but this response was independent of ATP12A. More importantly, chronic exposure of CF hAECs to esomeprazole alkalinized the ASL without disrupting the epithelial barrier integrity, but this increase in ASL pH was consistent with a decrease in mRNA expression of ATP12A. We conclude that PPIs may offer a new approach to restore ASL pH in CF airways, which is independent of CFTR.
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Affiliation(s)
- Livia Delpiano
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Joseph J. Thomas
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Annabel R. Yates
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Sarah J. Rice
- Skeletal Research Group, Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Michael A. Gray
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Vinciane Saint-Criq
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
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11
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ATP12A promotes mucus dysfunction during Type 2 airway inflammation. Sci Rep 2018; 8:2109. [PMID: 29391451 PMCID: PMC5794982 DOI: 10.1038/s41598-018-20444-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/16/2018] [Indexed: 12/23/2022] Open
Abstract
Allergic airway disease is known to cause significant morbidity due to impaired mucociliary clearance, however the mechanism that leads to the mucus dysfunction is not entirely understood. Interleukin 13 (IL-13), a key mediator of Type 2 (T2) inflammation, profoundly alters the ion transport properties of airway epithelium. However, these electrophysiological changes cannot explain the thick, tenacious airway mucus that characterizes the clinical phenotype. Here we report that IL-13 dramatically increases the airway surface liquid (ASL) viscosity in cultured primary human bronchial epithelial cells and thereby inhibits mucus clearance. These detrimental rheological changes require ATP12A, a non-gastric H+/K+-ATPase that secretes protons into the ASL. ATP12A knockdown or inhibition prevented the IL-13 dependent increase in ASL viscosity but did not alter the ASL pH. We propose that ATP12A promotes airway mucus dysfunction in individuals with T2 inflammatory airway diseases and that ATP12A may be a novel therapeutic target to improve mucus clearance.
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12
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Recent progress in the development of organic dye based near-infrared fluorescence probes for metal ions. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2017.06.011] [Citation(s) in RCA: 222] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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13
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Role of Smad3 and p38 Signalling in Cigarette Smoke-induced CFTR and BK dysfunction in Primary Human Bronchial Airway Epithelial Cells. Sci Rep 2017; 7:10506. [PMID: 28874823 PMCID: PMC5585359 DOI: 10.1038/s41598-017-11038-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/18/2017] [Indexed: 01/26/2023] Open
Abstract
Mucociliary clearance (MCC) is a major airway host defence system that is impaired in patients with smoking-associated chronic bronchitis. This dysfunction is partially related to a decrease of airway surface liquid (ASL) volume that is in part regulated by apically expressed cystic fibrosis transmembrane conductance regulator (CFTR) and large-conductance, Ca2+-activated, and voltage dependent K+ (BK) channels. Here, data from human bronchial epithelial cells (HBEC) confirm that cigarette smoke not only downregulates CFTR activity but also inhibits BK channel function, thereby causing ASL depletion. Inhibition of signalling pathways involved in cigarette smoke-induced channel dysfunction reveals that CFTR activity is downregulated via Smad3 signalling whereas BK activity is decreased via the p38 cascade. In addition, pre-treatment with pirfenidone, a drug presently used to inhibit TGF-β signalling in idiopathic pulmonary fibrosis, ameliorated BK dysfunction and ASL volume loss. Taken together, our results highlight the importance of not only CFTR but also BK channel function in maintaining ASL homeostasis and emphasize the possibility that pirfenidone could be employed as a novel therapeutic regimen to help improve MCC in smoking-related chronic bronchitis.
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14
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Li J, Yim D, Jang WD, Yoon J. Recent progress in the design and applications of fluorescence probes containing crown ethers. Chem Soc Rev 2017; 46:2437-2458. [DOI: 10.1039/c6cs00619a] [Citation(s) in RCA: 278] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Crown ethers, discovered by the winner of the Nobel Prize Charles Pedersen, are cyclic chemical compounds that consist of a ring or multiple rings containing several ether groups that are capable of binding various ions.
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Affiliation(s)
- Jun Li
- Department of Chemistry and Nanoscience
- Ewha Womans University
- Seoul 120-75
- Korea
| | - Dajeong Yim
- Department of Chemistry
- Yonsei university
- Seoul 03722
- Korea
| | - Woo-Dong Jang
- Department of Chemistry
- Yonsei university
- Seoul 03722
- Korea
| | - Juyoung Yoon
- Department of Chemistry and Nanoscience
- Ewha Womans University
- Seoul 120-75
- Korea
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15
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Kis A, Krick S, Baumlin N, Salathe M. Airway Hydration, Apical K(+) Secretion, and the Large-Conductance, Ca(2+)-activated and Voltage-dependent Potassium (BK) Channel. Ann Am Thorac Soc 2016; 13 Suppl 2:S163-8. [PMID: 27115952 PMCID: PMC5015721 DOI: 10.1513/annalsats.201507-405kv] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 09/08/2015] [Indexed: 01/20/2023] Open
Abstract
Large-conductance, calcium-activated, and voltage-gated K(+) (BK) channels are expressed in many tissues of the human body, where they play important roles in signaling not only in excitable but also in nonexcitable cells. Because BK channel properties are rendered in part by their association with four β and four γ subunits, their channel function can differ drastically, depending on in which cellular system they are expressed. Recent studies verify the importance of apically expressed BK channels for airway surface liquid homeostasis and therefore of their significant role in mucociliary clearance. Here, we review evidence that inflammatory cytokines, which contribute to airway diseases, can lead to reduced BK activity via a functional down-regulation of the γ regulatory subunit LRRC26. Therefore, manipulation of LRRC26 and pharmacological opening of BK channels represent two novel concepts of targeting epithelial dysfunction in inflammatory airway diseases.
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Affiliation(s)
- Adrian Kis
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami, Miami, Florida
| | - Stefanie Krick
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami, Miami, Florida
| | - Nathalie Baumlin
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami, Miami, Florida
| | - Matthias Salathe
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami, Miami, Florida
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16
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Hirata T, Terai T, Yamamura H, Shimonishi M, Komatsu T, Hanaoka K, Ueno T, Imaizumi Y, Nagano T, Urano Y. Protein-Coupled Fluorescent Probe To Visualize Potassium Ion Transition on Cellular Membranes. Anal Chem 2016; 88:2693-700. [PMID: 26894407 DOI: 10.1021/acs.analchem.5b03970] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
K(+) is the most abundant metal ion in cells, and changes of [K(+)] around cell membranes play important roles in physiological events. However, there is no practical method to selectively visualize [K(+)] at the surface of cells. To address this issue, we have developed a protein-coupled fluorescent probe for K(+), TLSHalo. TLSHalo is responsive to [K(+)] in the physiological range, with good selectivity over Na(+) and retains its K(+)-sensing properties after covalent conjugation with HaloTag protein. By using cells expressing HaloTag on the plasma membrane, we successfully directed TLSHalo specifically to the outer surface of target cells. This enabled us to visualize localized extracellular [K(+)] change with TLSHalo under a fluorescence microscope in real time. To confirm the experimental value of this system, we used TLSHalo to monitor extracellular [K(+)] change induced by K(+) ionophores or by activation of a native Ca(2+)-dependent K(+) channel (BK channel). Further, we show that K(+) efflux via BK channel induced by electrical stimulation at the bottom surface of the cells can be visualized with TLSHalo by means of total internal reflection fluorescence microscope (TIRFM) imaging. Our methodology should be useful to analyze physiological K(+) dynamics with high spatiotemporal resolution.
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Affiliation(s)
| | | | - Hisao Yamamura
- Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya 467-8603, Japan
| | | | | | | | | | - Yuji Imaizumi
- Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya 467-8603, Japan
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17
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Yin J, Hu Y, Yoon J. Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH. Chem Soc Rev 2016; 44:4619-44. [PMID: 25317749 DOI: 10.1039/c4cs00275j] [Citation(s) in RCA: 417] [Impact Index Per Article: 52.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.
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Affiliation(s)
- Jun Yin
- Department of Chemistry and Nano Science, Global Top 5 Research Program, Ewha Womans University, Seoul 120-750, Korea.
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18
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Schwarze T, Schneider R, Riemer J, Holdt HJ. A Highly K+-Selective Fluorescent Probe - Tuning the K+-Complex Stability and the K+/Na+Selectivity by Varying the Lariat-Alkoxy Unit of a Phenylaza[18]crown-6 Ionophore. Chem Asian J 2015; 11:241-7. [DOI: 10.1002/asia.201500956] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Indexed: 12/16/2022]
Affiliation(s)
- Thomas Schwarze
- Institut für Chemie, Anorganische Chemie; Universität Potsdam; Karl-Liebknecht-Str. 24-25 14476 Golm Germany
| | - Radu Schneider
- Institut für Chemie, Anorganische Chemie; Universität Potsdam; Karl-Liebknecht-Str. 24-25 14476 Golm Germany
| | - Janine Riemer
- Institut für Chemie, Anorganische Chemie; Universität Potsdam; Karl-Liebknecht-Str. 24-25 14476 Golm Germany
| | - Hans-Jürgen Holdt
- Institut für Chemie, Anorganische Chemie; Universität Potsdam; Karl-Liebknecht-Str. 24-25 14476 Golm Germany
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19
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Schwarze T, Riemer J, Eidner S, Holdt H. A Highly K
+
‐Selective Two‐Photon Fluorescent Probe. Chemistry 2015; 21:11306-10. [DOI: 10.1002/chem.201501473] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Thomas Schwarze
- Institut für Chemie, Anorganische Chemie, Universität Potsdam, Karl‐Liebknecht‐Str. 24–25, 14476 Golm (Germany)
| | - Janine Riemer
- Institut für Chemie, Anorganische Chemie, Universität Potsdam, Karl‐Liebknecht‐Str. 24–25, 14476 Golm (Germany)
| | - Sascha Eidner
- Institut für Chemie, Physikalische Chemie, Universität Potsdam, Karl‐Liebknecht‐Str. 24–25, 14476 Golm (Germany)
| | - Hans‐Jürgen Holdt
- Institut für Chemie, Anorganische Chemie, Universität Potsdam, Karl‐Liebknecht‐Str. 24–25, 14476 Golm (Germany)
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20
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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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21
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Hamilton GRC, Sahoo SK, Kamila S, Singh N, Kaur N, Hyland BW, Callan JF. Optical probes for the detection of protons, and alkali and alkaline earth metal cations. Chem Soc Rev 2015; 44:4415-32. [PMID: 25742963 DOI: 10.1039/c4cs00365a] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Luminescent sensors and switches continue to play a key role in shaping our understanding of key biochemical processes, assist in the diagnosis of disease and contribute to the design of new drugs and therapies. Similarly, their contribution to the environment cannot be understated as they offer a portable means to undertake field testing for hazardous chemicals and pollutants such as heavy metals. From a physiological perspective, the Group I and II metal ions are among the most important in the periodic table with blood plasma levels of H(+), Na(+) and Ca(2+) being indicators of several possible disease states. In this review, we examine the progress that has been made in the development of luminescent probes for Group I and Group II ions as well as protons. The potential applications of these probes and the mechanism involved in controlling their luminescent response upon analyte binding will also be discussed.
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Affiliation(s)
- Graham R C Hamilton
- Biomedical Sciences Research Institute, University of Ulster, Coleraine, Northern Ireland, BT52 1SA, UK.
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22
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Manzanares D, Srinivasan M, Salathe ST, Ivonnet P, Baumlin N, Dennis JS, Conner GE, Salathe M. IFN-γ-mediated reduction of large-conductance, Ca2+-activated, voltage-dependent K+ (BK) channel activity in airway epithelial cells leads to mucociliary dysfunction. Am J Physiol Lung Cell Mol Physiol 2014; 306:L453-62. [PMID: 24414257 DOI: 10.1152/ajplung.00247.2013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Effective mucociliary clearance (MCC) depends in part on adequate airway surface liquid (ASL) volume to maintain an appropriate periciliary fluid height that allows normal ciliary activity. Apically expressed large-conductance, Ca(2+)-activated, and voltage-dependent K(+) (BK) channels provide an electrochemical gradient for Cl(-) secretion and thus play an important role for adequate airway hydration. Here we show that IFN-γ decreases ATP-mediated apical BK activation in normal human airway epithelial cells cultured at the air-liquid interface. IFN-γ decreased mRNA levels of KCNMA1 but did not affect total protein levels. Because IFN-γ upregulates dual oxidase (DUOX)2 and therefore H2O2 production, we hypothesized that BK inactivation could be mediated by BK oxidation. However, DUOX2 knockdown did not affect the IFN-γ effect on BK activity. IFN-γ changed mRNA levels of the BK β-modulatory proteins KCNMB2 (increased) and KCNMB4 (decreased) as well as leucine-rich repeat-containing protein (LRRC)26 (decreased). Mallotoxin, a BK opener only in the absence of LRRC26, showed that BK channels lost their association with LRRC26 after IFN-γ treatment. Finally, IFN-γ caused a decrease in ciliary beating frequency that was immediately rescued by apical fluid addition, suggesting that it was due to ASL volume depletion. These data were confirmed with direct ASL measurements using meniscus scanning. Overexpression of KCNMA1, the pore-forming subunit of BK, overcame the reduction of ASL volume induced by IFN-γ. Key experiments were repeated in cystic fibrosis cells and showed the same results. Therefore, IFN-γ induces mucociliary dysfunction through BK inactivation.
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23
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Ast S, Schwarze T, Müller H, Sukhanov A, Michaelis S, Wegener J, Wolfbeis OS, Körzdörfer T, Dürkop A, Holdt HJ. A highly K(+)-selective phenylaza-[18]crown-6-lariat-ether-based fluoroionophore and its application in the sensing of K+ ions with an optical sensor film and in cells. Chemistry 2013; 19:14911-7. [PMID: 24105686 DOI: 10.1002/chem.201302350] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Indexed: 11/10/2022]
Abstract
Herein, we report the synthesis of two phenylaza-[18]crown-6 lariat ethers with a coumarin fluorophore (1 and 2) and we reveal that compound 1 is an excellent probe for K(+) ions under simulated physiological conditions. The presence of a 2-methoxyethoxy lariat group at the ortho position of the anilino moiety is crucial to the substantially increased stability of compounds 1 and 2 over their lariat-free phenylaza-[18]crown-6 ether analogues. Probe 1 shows a high K(+)/Na(+) selectivity and a 2.5-fold fluorescence enhancement was observed in the presence of 100 mM K(+) ions. A fluorescent membrane sensor, which was prepared by incorporating probe 1 into a hydrogel, showed a fully reversible response, a response time of 150 s, and a signal change of 7.8% per 1 mM K(+) within the range 1-10 mM K(+). The membrane was easily fabricated (only a single sensing layer on a solid polyester support), yet no leaching was observed. Moreover, compound 1 rapidly permeated into cells, was cytocompatible, and was suitable for the fluorescent imaging of K(+) ions on both the extracellular and intracellular levels.
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Affiliation(s)
- Sandra Ast
- Institut für Chemie, Anorganische Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Golm (Germany), Fax: (+49) 331-977-5055; School of Chemistry, University of Sydney, NSW 2006, Sydney (Australia)
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24
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Li X, Gao X, Shi W, Ma H. Design strategies for water-soluble small molecular chromogenic and fluorogenic probes. Chem Rev 2013; 114:590-659. [PMID: 24024656 DOI: 10.1021/cr300508p] [Citation(s) in RCA: 1185] [Impact Index Per Article: 107.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Xiaohua Li
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China
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25
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Frizzell RA, Hanrahan JW. Physiology of epithelial chloride and fluid secretion. Cold Spring Harb Perspect Med 2013; 2:a009563. [PMID: 22675668 DOI: 10.1101/cshperspect.a009563] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epithelial salt and water secretion serves a variety of functions in different organ systems, such as the airways, intestines, pancreas, and salivary glands. In cystic fibrosis (CF), the volume and/or composition of secreted luminal fluids are compromised owing to mutations in the gene encoding CFTR, the apical membrane anion channel that is responsible for salt secretion in response to cAMP/PKA stimulation. This article examines CFTR and related cellular transport processes that underlie epithelial anion and fluid secretion, their regulation, and how these processes are altered in CF disease to account for organ-specific secretory phenotypes.
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Affiliation(s)
- Raymond A Frizzell
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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26
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In vivo determination of mouse olfactory mucus cation concentrations in normal and inflammatory states. PLoS One 2012; 7:e39600. [PMID: 22911687 PMCID: PMC3401282 DOI: 10.1371/journal.pone.0039600] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 05/25/2012] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Olfaction is impaired in chronic rhinosinusitis (CRS). The study has two aims: (1) to determine whether changes in cation concentration occur in the olfactory mucus of mice with CRS, which may affect chemo-electrical transduction, (2) and to examine whether these alterations are physiologically significant in humans. STUDY DESIGN Animal study in mice and translational study in humans. METHODS Inflammation was induced by sensitization and chronic exposure of 16 C57BL/6 mice to Aspergillus fumigatus. The control group included 16 untreated mice. Ion-selective microelectrodes were used to measure free cation concentrations in the olfactory mucus of 8 mice from each treatment group, while the remaining mice were sacrificed for histology. To validate the findings in the animal model, olfactory threshold was measured in 11 healthy human participants using Sniffin' Sticks before and after nasal irrigation with solutions that were composed of either of the cation concentrations. RESULTS In 8 mice, olfactory mucus of chronically inflamed mice had lower [Na(+)] (84.8±4.45 mM versus 93.73±3.06 mM, p = 0.02), and higher [K(+)] (7.2±0.65 mM versus 5.7±0.20 mM, p = 0.04) than controls. No difference existed in [Ca(2+)] (0.50±0.12 mM versus 0.54±0.06 mM, p = 0.39). In humans, rinsing with solutions replicating ion concentrations of the mouse mucosa with chronic inflammation caused a significant elevation in the median olfactory threshold (9.0 to 4.8, p = 0.003) but not with the control solution (8.3 to 7.8, p = 0.75). CONCLUSION Chronic inflammation elevates potassium and lowers sodium ion concentration in mice olfactory mucus. Nasal irrigation with a corresponding solution induced olfactory threshold shift in humans.
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Zhou X, Su F, Tian Y, Youngbull C, Johnson RH, Meldrum DR. A new highly selective fluorescent K+ sensor. J Am Chem Soc 2011; 133:18530-3. [PMID: 22026580 DOI: 10.1021/ja207345s] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe the synthesis, properties, and application of a new fluorescent potassium chemosensor, KS2, for K(+) sensing and imaging in live cells. By virtue of a strong electron-withdrawing group, 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF), with a triazacryptand ligand, the new sensor can respond to K(+) up to 1.6 M. This is the first highly selective intracellular sensor suitable for sensing K(+) over a broad and high concentration range. Confocal fluorescence microscopy has established the utility of KS2 for live-cell K(+) detection. The application of KS2 combined with other sensors will be of great benefit for investigating cellular metabolism, detecting and diagnosing diseases including cancer, and monitoring responses to therapy.
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Affiliation(s)
- Xianfeng Zhou
- Center for Biosignatures Discovery Automation, Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA
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28
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Zhao KQ, Xiong G, Wilber M, Cohen NA, Kreindler JL. A role for two-pore K⁺ channels in modulating Na⁺ absorption and Cl⁻ secretion in normal human bronchial epithelial cells. Am J Physiol Lung Cell Mol Physiol 2011; 302:L4-L12. [PMID: 21964404 DOI: 10.1152/ajplung.00102.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mucociliary clearance is the primary innate physical defense mechanism against inhaled pathogens and toxins. Vectorial ion transport, primarily sodium absorption and anion secretion, by airway epithelial cells supports mucociliary clearance. This is evidenced by diseases of abnormal ion transport such as cystic fibrosis and pseudohypoaldosteronism that are characterized by changes in mucociliary clearance. Sodium absorption and chloride secretion in human bronchial epithelial cells depend on potassium channel activity, which creates a favorable electrochemical gradient for both by hyperpolarizing the apical plasma membrane. Although the role of basolateral membrane potassium channels is firmly established and extensively studied, a role for apical membrane potassium channels has also been described. Here, we demonstrate that bupivacaine and quinidine, blockers of four-transmembrane domain, two-pore potassium (K2P) channels, inhibit both amiloride-sensitive sodium absorption and forskolin-stimulated anion secretion in polarized, normal human bronchial epithelial cells at lower concentrations when applied to the mucosal surface than when applied to the serosal surface. Transcripts from four genes, KCNK1 (TWIK-1), KCNK2 (TREK-1), KCNK5 (TASK-2), and KCNK6 (TWIK-2), encoding K2P channels were identified by RT-PCR. Protein expression at the apical membrane was confirmed by immunofluorescence. Our data provide further evidence that potassium channels, in particular K2P channels, are expressed and functional in the apical membrane of airway epithelial cells where they may be targets for therapeutic manipulation.
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Affiliation(s)
- Ke-Qing Zhao
- Department of Otorhinolaryngology-Head and Neck Surgery, Eye and Ear, Nose and Throat Hospital, School of Shanghai Medicine, Fudan University, Shanghai, Peoples Republic of China
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29
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Zhou X, Su F, Gao W, Tian Y, Youngbull C, Johnson RH, Meldrum DR. Triazacryptand-based fluorescent sensors for extracellular and intracellular K+ sensing. Biomaterials 2011; 32:8574-83. [PMID: 21855134 DOI: 10.1016/j.biomaterials.2011.07.081] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 07/28/2011] [Indexed: 02/01/2023]
Abstract
A 4-amino-naphthalimide derived fluorophore with a triazacryptand moiety ligand was synthesized as a potassium ion (K(+)) sensor (KS1). This sensor is a monomer possessing a polymerizable vinyl group. By taking advantage of the polymerizable characteristics of the vinyl group, KS1 was polymerized with 2-hydroxyethyl methacrylate (HEMA) and acrylamide (AM) to form K(+) sensing films for extracellular sensing. The sensitivity of the films to potassium ions can be further tuned through the adjustment of the HEMA and AM weight ratios as well as introduction of positive or negative charge-containing segments. KS1 and its poly(2-hydroxyethyl methacrylate)-co-poly(acrylamide) (PHEMA-co-PAM) thin films show high selectivity for K(+) over competing sodium ions (Na(+)) at physiological concentrations. Extracellular sensing was demonstrated using a KS1-conjugated PHEMA-co-PAM thin film to measure the K(+) efflux of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) stimulated by lysozyme. Meanwhile, KS1 itself permeates human glioblastoma U87MG and human esophagus premalignant CP-A cell lines. KS1 was used to monitor K(+) efflux stimulated by adenosine-5'-triphosphate (ATP), amphotericin, and a mixture of nigericin, bumetanide and ouabain, demonstrating application of this material as an intracellular potassium ion sensor.
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Affiliation(s)
- Xianfeng Zhou
- Center for Biosignatures Discovery Automation, Biodesign Institute, Arizona State University, 1001S McAllister Ave, Tempe, AZ 85287, USA
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Abstract
This critical review covers the advances made using the 4-bora-3a,4a-diaza-s-indacene (BODIPY) scaffold as a fluorophore in the design, synthesis and application of fluorescent indicators for pH, metal ions, anions, biomolecules, reactive oxygen species, reactive nitrogen species, redox potential, chemical reactions and various physical phenomena. The sections of the review describing the criteria for rational design of fluorescent indicators and the mathematical expressions for analyzing spectrophotometric and fluorometric titrations are applicable to all fluorescent probes (206 references).
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Affiliation(s)
- Noël Boens
- Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200f - bus 02404, 3001 Heverlee (Leuven), Belgium.
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31
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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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32
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Carpenter RD, Verkman AS. Function-Oriented Synthesis of a Didesmethyl Triazacryptand Analogue for Fluorescent Potassium Ion Sensing. European J Org Chem 2011; 2011:1242-1248. [PMID: 23914138 PMCID: PMC3729919 DOI: 10.1002/ejoc.201001450] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Indexed: 11/10/2022]
Abstract
Triazacryptand (TAC)-based fluorescent K+ sensors have broad biomedical utility, yet their advancement has been hindered because of their challenging synthesis. Herein, an efficient synthesis is reported that delivers a didesmethyl tri-azacryptand (ddTAC) K+ sensor in twofold fewer steps and ninefold higher overall yield than the original TAC synthesis. Our synthesis utilizes a C-O dianionic oxidative macrocyclization and reports new examples of aminoarylations and a microwave route to xanthythilium chromophores. The K+ sensitivity and selectivity of the ddTAC-based sensor are comparable to the TAC-based sensor.
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Affiliation(s)
- Richard D. Carpenter
- Departments of Medicine and Physiology, University of California, San Francisco, Health Sciences East, Room 1246, Box 0521, 513 Parnassus Ave., San Francisco, CA 94143-0521, USA
- Department of Biomedical Engineering, University of California, Davis, Genome and Biomedical Sciences Facility, 451 Health Sciences Dr., Davis, CA 95616, USA
| | - Alan S. Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, Health Sciences East, Room 1246, Box 0521, 513 Parnassus Ave., San Francisco, CA 94143-0521, USA
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Albertazzi L, Storti B, Marchetti L, Beltram F. Delivery and subcellular targeting of dendrimer-based fluorescent pH sensors in living cells. J Am Chem Soc 2010; 132:18158-67. [PMID: 21141854 DOI: 10.1021/ja105689u] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Synthesis and targeted delivery of dendrimer-based fluorescent biosensors in living HeLa cells are reported. Following electroporation dendrimers are shown to display specific subcellular localization depending on their size and surface charge and this property is preserved when they are functionalized with sensing moieties. We analyze the case of double dendrimer conjugation with pH-sensitive and pH-insensitive molecules leading to the realization of ratiometric pH sensors that are calibrated in vitro and in living cells. By tuning the physicochemical properties of the dendrimer scaffold sensors can be targeted to specific cellular compartments allowing selective pH measurements in different organelles in living cells. In order to demonstrate the modularity of this approach we present three different pH sensors with tuned H(+) affinity by appropriately choosing the pH-sensitive dye. We argue that the present methodology represents a general approach toward the realization of targetable ratiometric sensors suitable to monitor biologically relevant ions or molecules in living cells.
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Affiliation(s)
- Lorenzo Albertazzi
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, 56127 Pisa, Italy.
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34
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Thiagarajah JR, Song Y, Derichs N, Verkman AS. Airway surface liquid depth imaged by surface laser reflectance microscopy. ACTA ACUST UNITED AC 2010; 136:353-62. [PMID: 20713545 PMCID: PMC2931148 DOI: 10.1085/jgp.201010490] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The thin layer of liquid at the surface of airway epithelium, the airway surface liquid (ASL), is important in normal airway physiology and in the pathophysiology of cystic fibrosis. At present, the best method to measure ASL depth involves scanning confocal microscopy after staining with an aqueous-phase fluorescent dye. We describe here a simple, noninvasive imaging method to measure ASL depth by reflectance imaging of an epithelial mucosa in which the surface is illuminated at a 45-degree angle by an elongated 13-µm wide rectangular beam produced by a 670-nm micro-focus laser. The principle of the method is that air–liquid, liquid–liquid, and liquid–cell interfaces produce distinct specular or diffuse reflections that can be imaged to give a micron-resolution replica of the mucosal surface. The method was validated using fluid layers of specified thicknesses and applied to measure ASL depth in cell cultures and ex vivo fragments of pig trachea. In addition, the method was adapted to measure transepithelial fluid transport from the dynamics of fluid layer depth. Compared with confocal imaging, ASL depth measurement by surface laser reflectance microscopy does not require dye staining or costly instrumentation, and can potentially be adapted for in vivo measurements using fiberoptics.
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Affiliation(s)
- Jay R Thiagarajah
- Department of Medicine, University of California, San Francisco, CA 94143, USA
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Namkung W, Thiagarajah JR, Phuan PW, Verkman AS. Inhibition of Ca2+-activated Cl- channels by gallotannins as a possible molecular basis for health benefits of red wine and green tea. FASEB J 2010; 24:4178-86. [PMID: 20581223 DOI: 10.1096/fj.10-160648] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
TMEM16A was found recently to be a calcium-activated Cl(-) channel (CaCC). CaCCs perform important functions in cell physiology, including regulation of epithelial secretion, cardiac and neuronal excitability, and smooth muscle contraction. CaCC modulators are of potential utility for treatment of hypertension, diarrhea, and cystic fibrosis. Screening of drug and natural product collections identified tannic acid as an inhibitor of TMEM16A, with IC(50) ∼ 6 μM and ∼100% inhibition at higher concentrations. Tannic acid inhibited CaCCs in multiple cell types but did not affect CFTR Cl(-) channels. Structure-activity analysis indicated the requirement of gallic or digallic acid substituents on a macromolecular scaffold (gallotannins), as are present in green tea and red wine. Other polyphenolic components of teas and wines, including epicatechin, catechin, and malvidin-3-glucoside, poorly inhibited CaCCs. Remarkably, a 1000-fold dilution of red wine and 100-fold dilution of green tea inhibited CaCCs by >50%. Tannic acid, red wine, and green tea inhibited arterial smooth muscle contraction and intestinal Cl(-) secretion. Gallotannins are thus potent CaCC inhibitors whose biological activity provides a potential molecular basis for the cardioprotective and antisecretory benefits of red wine and green tea.
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Affiliation(s)
- Wan Namkung
- Department of Medicine , University of California, San Francisco, CA 94143-0521, USA
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Namkung W, Finkbeiner WE, Verkman AS. CFTR-adenylyl cyclase I association responsible for UTP activation of CFTR in well-differentiated primary human bronchial cell cultures. Mol Biol Cell 2010; 21:2639-48. [PMID: 20554763 PMCID: PMC2912350 DOI: 10.1091/mbc.e09-12-1004] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Chloride secretion by airway epithelial cells is defective in cystic fibrosis (CF). The conventional paradigm is that CFTR is activated through cAMP and protein kinase A (PKA), whereas the Ca(2+)-activated chloride channel (CaCC) is activated by Ca(2+) agonists like UTP. We found that most chloride current elicited by Ca(2+) agonists in primary cultures of human bronchial epithelial cells is mediated by CFTR by a mechanism involving Ca(2+) activation of adenylyl cyclase I (AC1) and cAMP/PKA signaling. Use of selective inhibitors showed that Ca(2+) agonists produced more chloride secretion from CFTR than from CaCC. CFTR-dependent chloride secretion was reduced by PKA inhibition and was absent in CF cell cultures. Ca(2+) agonists produced cAMP elevation, which was blocked by adenylyl cyclase inhibition. AC1, a Ca(2+)/calmodulin-stimulated adenylyl cyclase, colocalized with CFTR in the cell apical membrane. RNAi knockdown of AC1 selectively reduced UTP-induced cAMP elevation and chloride secretion. These results, together with correlations between cAMP and chloride current, suggest that compartmentalized AC1-CFTR association is responsible for Ca(2+)/cAMP cross-talk. We further conclude that CFTR is the principal chloride secretory pathway in non-CF airways for both cAMP and Ca(2+) agonists, providing a novel mechanism to link CFTR dysfunction to CF lung disease.
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Affiliation(s)
- Wan Namkung
- Department of Medicine and Physiology, University of California, San Francisco, CA 94143, USA
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Savitski AN, Mesaros C, Blair IA, Cohen NA, Kreindler JL. Secondhand smoke inhibits both Cl- and K+ conductances in normal human bronchial epithelial cells. Respir Res 2009; 10:120. [PMID: 19943936 PMCID: PMC2792224 DOI: 10.1186/1465-9921-10-120] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 11/27/2009] [Indexed: 11/21/2022] Open
Abstract
Secondhand smoke (SHS) exposure is an independent risk factor for asthma, rhinosinusitis, and more severe respiratory tract infections in children and adults. Impaired mucociliary clearance with subsequent mucus retention contributes to the pathophysiology of each of these diseases, suggesting that altered epithelial salt and water transport may play an etiological role. To test the hypothesis that SHS would alter epithelial ion transport, we designed a system for in vitro exposure of mature, well-differentiated human bronchial epithelial cells to SHS. We show that SHS exposure inhibits cAMP-stimulated, bumetanide-sensitive anion secretion by 25 to 40% in a time-dependent fashion in these cells. Increasing the amount of carbon monoxide to 100 ppm from 5 ppm did not increase the amount of inhibition, and filtering SHS reduced inhibition significantly. It was determined that SHS inhibited cAMP-dependent apical membrane chloride conductance by 25% and Ba2+-sensitive basolateral membrane potassium conductance by 50%. These data confirm previous findings that cigarette smoke inhibits chloride secretion in a novel model of smoke exposure designed to mimic SHS exposure. They also extend previous findings to demonstrate an effect on basolateral K+ conductance. Therefore, pharmacological agents that increase either apical membrane chloride conductance or basolateral membrane potassium conductance might be of therapeutic benefit in patients with diseases related to SHS exposure.
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Affiliation(s)
- Amy N Savitski
- Division of Pulmonary Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
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