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Nastev A, Sommer JU, Behr W, Stuck BA, Mueller CE, Schell A, Kramer B, Haeussler D, Hoermann K, Birk R. Cocaine Reduces Ciliary Beat Frequency of Human Nasal Epithelial Cells. In Vivo 2021; 34:3285-3289. [PMID: 33144435 DOI: 10.21873/invivo.12166] [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: 08/22/2020] [Revised: 09/06/2020] [Accepted: 09/13/2020] [Indexed: 11/10/2022]
Abstract
BACKGROUND/AIM Cocaine is a widely used recreational drug and is known for its nasal complications including epithelial, cartilage and bone damage. The aim of the study was to analyze the impact of cocaine on ciliary beat frequency (CBF) of human nasal epithelial cells and therefore better understand its side effects on nasal mucosa. MATERIALS AND METHODS Nasal epithelial cells of 21 healthy subjects were harvested and exposed in vitro to cocaine hydrochloride solutions ranging from 0.875% to 7%. High-speed video footage was acquired with phase contrast microscopy and CBF was analyzed with Sissons-Ammons Video Analysis (SAVA) software. RESULTS All tested concentrations led to a significant reduction in CBF compared to the control. Effects increased over time and with concentration. A mechanical inhibition of cilia by cocaine crystals was also observed. CONCLUSION We assume that CBF reduction is part of the pathomechanism leading to nasal complications in cocaine abuse. Considering these results, clinical usage of cocaine should be critically evaluated and restricted to select cases only.
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Affiliation(s)
- Alexander Nastev
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-Universität Marburg, Marburg, Germany
| | - J Ulrich Sommer
- Department of Otorhinolaryngology, Head and Neck Surgery, Helios University Hospital Wuppertal, Wuppertal, Germany
| | - Wieland Behr
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-Universität Marburg, Marburg, Germany
| | - Boris A Stuck
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-Universität Marburg, Marburg, Germany
| | - C Emika Mueller
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-Universität Marburg, Marburg, Germany
| | - Angela Schell
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Mannheim, Mannheim Medical Faculty, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Benedikt Kramer
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Mannheim, Mannheim Medical Faculty, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Daniel Haeussler
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Mannheim, Mannheim Medical Faculty, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Karl Hoermann
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Mannheim, Mannheim Medical Faculty, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Richard Birk
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Marburg, Philipps-Universität Marburg, Marburg, Germany
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Ahuja M, Chung WY, Lin WY, McNally BA, Muallem S. Ca 2+ Signaling in Exocrine Cells. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035279. [PMID: 31636079 DOI: 10.1101/cshperspect.a035279] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Calcium (Ca2+) and cyclic AMP (cAMP) signaling cross talk and synergize to stimulate the cardinal functions of exocrine cells, regulated exocytosis, and fluid and electrolyte secretion. This physiological process requires the organization of the two signaling pathways into complexes at defined cellular domains and close placement. Such domains are formed by membrane contact sites (MCS). This review discusses the basic properties of Ca2+ signaling in exocrine cells, the role of MCS in the organization of cell signaling and in cross talk and synergism between the Ca2+ and cAMP signaling pathways and, finally, the mechanism by which the Ca2+ and cAMP pathways synergize to stimulate epithelial fluid and electrolyte secretion.
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Affiliation(s)
- Malini Ahuja
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Woo Young Chung
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Wei-Yin Lin
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Beth A McNally
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892
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Krick S, Wang J, St-Pierre M, Gonzalez C, Dahl G, Salathe M. Dual Oxidase 2 (Duox2) Regulates Pannexin 1-mediated ATP Release in Primary Human Airway Epithelial Cells via Changes in Intracellular pH and Not H2O2 Production. J Biol Chem 2016; 291:6423-32. [PMID: 26823467 DOI: 10.1074/jbc.m115.664854] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Indexed: 11/06/2022] Open
Abstract
Human airway epithelial cells express pannexin 1 (Panx1) channels to release ATP, which regulates mucociliary clearance. Airway inflammation causes mucociliary dysfunction. Exposure of primary human airway epithelial cell cultures to IFN-γ for 48 h did not alter Panx1 protein expression but significantly decreased ATP release in response to hypotonic stress. The IFN-γ-induced functional down-regulation of Panx1 was due to the up-regulation of dual oxidase 2 (Duox2). Duox2 suppression by siRNA led to an increase in ATP release in control cells and restoration of ATP release in cells treated with IFN-γ. Both effects were reduced by the pannexin inhibitor probenecid. Duox2 up-regulation stoichiometrically increases H2O2 and proton production. H2O2 inhibited Panx1 function temporarily by formation of disulfide bonds at the thiol group of its terminal cysteine. Long-term exposure to H2O2, however, had no inhibitory effect. To assess the role of cellular acidification upon IFN-γ treatment, fully differentiated airway epithelial cells were exposed to ammonium chloride to alkalinize the cytosol. This led to a 2-fold increase in ATP release in cells treated with IFN-γ that was also inhibited by probenecid. Duox2 knockdown also partially corrected IFN-γ-mediated acidification. The direct correlation between intracellular pH and Panx1 open probability was shown in oocytes. Therefore, airway epithelial cells release less ATP in response to hypotonic stress in an inflammatory environment (IFN-γ exposure). Decreased Panx1 function is a response to cell acidification mediated by IFN-γ-induced up-regulation of Duox2, representing a novel mechanism for mucociliary dysfunction in inflammatory airway diseases.
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Affiliation(s)
- Stefanie Krick
- From the Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine and
| | - Junjie Wang
- Department of Physiology and Biophysics, University of Miami, Miami, Florida 33136 and
| | - Melissa St-Pierre
- From the Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine and
| | - Carlos Gonzalez
- the Interdisciplinary Center for Neuroscience of Valparaíso, Universidad de Valparaíso, Valparaíso, 2362735, Chile
| | - Gerhard Dahl
- Department of Physiology and Biophysics, University of Miami, Miami, Florida 33136 and
| | - Matthias Salathe
- From the Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine and
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Son A, Park S, Shin DM, Muallem S. Orai1 and STIM1 in ER/PM junctions: roles in pancreatic cell function and dysfunction. Am J Physiol Cell Physiol 2016; 310:C414-22. [PMID: 26739495 DOI: 10.1152/ajpcell.00349.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membrane contact sites (MCS) are critical junctions that form between the endoplasmic reticulum (ER) and membranes of various organelles, including the plasma membrane (PM). Signaling complexes, including mediators of Ca(2+) signaling, are assembled within MCS, such as the ER/PM junction. This is most evident in polarized epithelial cells, such as pancreatic cells. Core Ca(2+) signaling proteins cluster at the apical pole, the site of inositol 1,4,5-trisphosphate-mediated Ca(2+) release and Orai1/transient receptor potential canonical-mediated store-dependent Ca(2+) entry. Recent advances have characterized the proteins that tether the membranes at MCS and the role of these proteins in modulating physiological and pathological intracellular signaling. This review discusses recent advances in the characterization of Ca(2+) signaling at ER/PM junctions and the relation of these junctions to physiological and pathological Ca(2+) signaling in pancreatic acini.
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Affiliation(s)
- Aran Son
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Seonghee Park
- Department of Physiology, School of Medicine, Ewha Womans University, Seoul, Korea
| | - Dong Min Shin
- Department of Oral Biology, BK 21 PLUS Project, Yonsei University College of Dentistry, Seoul, Korea
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland;
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Schmid A, Baumlin N, Ivonnet P, Dennis JS, Campos M, Krick S, Salathe M. Roflumilast partially reverses smoke-induced mucociliary dysfunction. Respir Res 2015; 16:135. [PMID: 26521141 PMCID: PMC4628339 DOI: 10.1186/s12931-015-0294-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 10/17/2015] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Phosphodiesterases (PDEs) break down cAMP, thereby regulating intracellular cAMP concentrations and diffusion. Since PDE4 predominates in airway epithelial cells, PDE4 inhibitors can stimulate Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) by increasing cAMP. Tobacco smoking and COPD are associated with decreased CFTR function and impaired mucociliary clearance (MCC). However, the effects of the PDE4 inhibitor roflumilast on smoke-induced mucociliary dysfunction have not been fully explored. METHODS Primary normal human bronchial epithelial cells (NHBE) from non-smokers, cultured at the air-liquid interface (ALI) were used for most experiments. Cultures were exposed to cigarette smoke in a Vitrocell VC-10 smoking robot. To evaluate the effect of roflumilast on intracellular cAMP concentrations, fluorescence resonance energy transfer (FRET) between CFP- and YFP-tagged protein kinase A (PKA) subunits was recorded. Airway surface liquid (ASL) was measured using light refraction scanning and ciliary beat frequency (CBF) employing infrared differential interference contrast microscopy. Chloride conductance was measured in Ussing chambers and CFTR expression was quantified with qPCR. RESULTS While treatment with 100 nM roflumilast had little effect alone, it increased intracellular cAMP upon stimulation with forskolin and albuterol in cultures exposed to cigarette smoke and in control conditions. cAMP baselines were lower in smoke-exposed cells. Roflumilast prolonged cAMP increases in smoke-exposed and control cultures. Smoke-induced reduction in functional, albuterol-mediated chloride conductance through CFTR was improved by roflumilast. ASL volumes also increased in smoke-exposed cultures in the presence of roflumilast while it did not in its absence. Cigarette smoke exposure decreased CBF, an effect rescued with roflumilast, particularly when used together with the long-acting ß-mimetic formoterol. Roflumilast also enhanced forskolin-induced CBF stimulation in ASL volume supplemented smoked and control cells, confirming the direct stimulatory effect of rising cAMP on ciliary function. In active smokers, CFTR mRNA expression was increased compared to non-smokers and ex-smokers. Roflumilast also increased CFTR mRNA levels in cigarette-smoke exposed cell cultures. CONCLUSIONS Our results show that roflumilast can rescue smoke-induced mucociliary dysfunction by reversing decreased CFTR activity, augmenting ASL volume, and stimulating CBF, the latter particularly in combination with formoterol. As expected, CFTR mRNA expression was not indicative of apical CFTR function.
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Affiliation(s)
- Andreas Schmid
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
| | - Nathalie Baumlin
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
| | - Pedro Ivonnet
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
| | - John S Dennis
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
| | - Michael Campos
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
| | - Stefanie Krick
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
| | - Matthias Salathe
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, University of Miami Miller School of Medicine, 1600 NW 10th Ave, RMSB #7058, Miami, FL, 33136, USA.
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Cao X, Choi S, Maléth JJ, Park S, Ahuja M, Muallem S. The ER/PM microdomain, PI(4,5)P₂ and the regulation of STIM1-Orai1 channel function. Cell Calcium 2015; 58:342-8. [PMID: 25843208 PMCID: PMC4564333 DOI: 10.1016/j.ceca.2015.03.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 03/06/2015] [Accepted: 03/09/2015] [Indexed: 12/18/2022]
Abstract
All forms of cell signaling occur in discreet cellular microdomains in which the ER is the main participant and include microdomains formed by the ER with lysosomes, endosomes, the nucleus, mitochondria and the plasma membrane. In the microdomains the two opposing organelles transfer and exchange constituents including lipids and ions. As is the case for other forms of signaling pathways, many components of the receptor-evoked Ca(2+) signal are clustered at the ER/PM microdomain, including the Orai1-STIM1 complex. This review discusses recent advances in understanding the molecular components that tether the ER and plasma membrane to form the ER/PM microdomains in which PI(4,5)P2 is enriched, and how dynamic targeting of the Orai1-STIM1 complex to PI(4,5)P2-poor and PI(4,5)P2-rich microdomains controls the activity of Orai1 and its regulation by Ca(2+) that is mediated by SARAF.
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Affiliation(s)
- Xu Cao
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, United States
| | - Seok Choi
- Department of Physiology, College of Medicine, Chosun University, 501-375, Republic of Korea
| | - Jozsef J Maléth
- First Department of Medicine, University of Szeged, Szeged H-6725, Hungary
| | - Seonghee Park
- Department of Physiology, School of Medicine, Ewha Womans University, 911-1 Mok-6-dong, Yang Chun-gu, Seoul 158-710, Republic of Korea
| | - Malini Ahuja
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, United States
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, NIDCR, NIH, Bethesda, MD 20892, United States.
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Chen X, Baumlin N, Buck J, Levin LR, Fregien N, Salathe M. A soluble adenylyl cyclase form targets to axonemes and rescues beat regulation in soluble adenylyl cyclase knockout mice. Am J Respir Cell Mol Biol 2015; 51:750-60. [PMID: 24874272 DOI: 10.1165/rcmb.2013-0542oc] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Ciliary beating is important for effective mucociliary clearance. Soluble adenylyl cyclase (sAC) regulates ciliary beating, and a roughly 50-kD sAC variant is expressed in axonemes. Normal human bronchial epithelial (NHBE) cells express multiple sAC splice variants: full-length sAC; variants with catalytic domain 1 (C1) deletions; and variants with partial C1. One variant, sACex5v2-ex12v2, contains two alternative splices creating new exons 5 (ex5v2) and 12 (ex12v2), encoding a roughly 45-kD protein. It is therefore similar in size to ciliary sAC. The variant increases in expression upon ciliogenesis during differentiation at the air-liquid interface. When expressed in NHBE cells, this variant was targeted to cilia. Exons 5v2-7 were important for ciliary targeting, whereas exons 2-4 prevented it. In vitro, cytoplasmic sACex2-ex12v2 (containing C1 and C2) was the only variant producing cAMP. Ciliary sACex5v2-ex12v2 was not catalytically active. Airway epithelial cells isolated from wild-type mice revealed sAC-dependent ciliary beat frequency (CBF) regulation, analogous to NHBE cells: CBF rescue from HCO3(-)/CO2-mediated intracellular acidification was sensitive to the sAC inhibitor, KH7. Compared with wild type, sAC C2 knockout (KO) mice revealed lower CBF baseline, and the HCO3(-)/CO2-mediated CBF decrease was not inhibited by KH7, confirming lack of functional sAC. Human sACex5v2-ex12v2 was targeted to cilia and sACex2-ex12v2 to the cytoplasm in these KO mice. Introduction of the ciliary sACex5v2-ex12v2 variant, but not the cytoplasmic sACex2-ex12v2, restored functional sAC activity in C2 KO mice. Thus, we show, for the first time, a mammalian axonemal targeting sequence that localizes a sAC variant to cilia to regulate CBF.
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Affiliation(s)
- Xi Chen
- 1 Division of Pulmonary, Allergy, Critical Care & Sleep Medicine
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Soluble adenylyl cyclase in health and disease. Biochim Biophys Acta Mol Basis Dis 2014; 1842:2584-92. [PMID: 25064591 DOI: 10.1016/j.bbadis.2014.07.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 07/12/2014] [Accepted: 07/15/2014] [Indexed: 12/14/2022]
Abstract
The second messenger cAMP is integral for many physiological processes. Soluble adenylyl cyclase (sAC) was recently identified as a widely expressed intracellular source of cAMP in mammalian cells. sAC is evolutionary, structurally, and biochemically distinct from the G-protein-responsive transmembranous adenylyl cyclases (tmAC). The structure of the catalytic unit of sAC is similar to tmAC, but sAC does not contain transmembranous domains, allowing localizations independent of the membranous compartment. sAC activity is stimulated by HCO(3)(-), Ca²⁺ and is sensitive to physiologically relevant ATP fluctuations. sAC functions as a physiological sensor for carbon dioxide and bicarbonate, and therefore indirectly for pH. Here we review the physiological role of sAC in different human tissues with a major focus on the lung. This article is part of a Special Issue entitled: The role of soluble adenylyl cyclase in health and disease, guest edited by J. Buck and L.R. Levin.
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Contribution of α7 nicotinic receptor to airway epithelium dysfunction under nicotine exposure. Proc Natl Acad Sci U S A 2013; 110:4099-104. [PMID: 23431157 DOI: 10.1073/pnas.1216939110] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Loss or dysfunction of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) leads to impairment of airway mucus transport and to chronic lung diseases resulting in progressive respiratory failure. Nicotinic acetylcholine receptors (nAChRs) bind nicotine and nicotine-derived nitrosamines and thus mediate many of the tobacco-related deleterious effects in the lung. Here we identify α7 nAChR as a key regulator of CFTR in the airways. The airway epithelium in α7 knockout mice is characterized by a higher transepithelial potential difference, an increase of amiloride-sensitive apical Na(+) absorption, a defective cAMP-dependent Cl(-) conductance, higher concentrations of Na(+), Cl(-), K(+), and Ca(2+) in secretions, and a decreased mucus transport, all relevant to a deficient CFTR activity. Moreover, prolonged nicotine exposure mimics the absence of α7 nAChR in mice or its inactivation in vitro in human airway epithelial cell cultures. The functional coupling of α7 nAChR to CFTR occurs through Ca(2+) entry and activation of adenylyl cyclases, protein kinase A, and PKC. α7 nAChR, CFTR, and adenylyl cyclase-1 are physically and functionally associated in a macromolecular complex within lipid rafts at the apical membrane of surface and glandular airway epithelium. This study establishes the potential role of α7 nAChR in the regulation of CFTR function and in the pathogenesis of smoking-related chronic lung diseases.
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Burnstock G, Brouns I, Adriaensen D, Timmermans JP. Purinergic signaling in the airways. Pharmacol Rev 2012; 64:834-68. [PMID: 22885703 DOI: 10.1124/pr.111.005389] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Evidence for a significant role and impact of purinergic signaling in normal and diseased airways is now beyond dispute. The present review intends to provide the current state of knowledge of the involvement of purinergic pathways in the upper and lower airways and lungs, thereby differentiating the involvement of different tissues, such as the epithelial lining, immune cells, airway smooth muscle, vasculature, peripheral and central innervation, and neuroendocrine system. In addition to the vast number of well illustrated functions for purinergic signaling in the healthy respiratory tract, increasing data pointing to enhanced levels of ATP and/or adenosine in airway secretions of patients with airway damage and respiratory diseases corroborates the emerging view that purines act as clinically important mediators resulting in either proinflammatory or protective responses. Purinergic signaling has been implicated in lung injury and in the pathogenesis of a wide range of respiratory disorders and diseases, including asthma, chronic obstructive pulmonary disease, inflammation, cystic fibrosis, lung cancer, and pulmonary hypertension. These ostensibly enigmatic actions are based on widely different mechanisms, which are influenced by the cellular microenvironment, but especially the subtypes of purine receptors involved and the activity of distinct members of the ectonucleotidase family, the latter being potential protein targets for therapeutic implementation.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Royal Free Campus, London, UK.
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11
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Abstract
Motile cilia in the airway epithelium are the engine for mucociliary clearance, the mechanism responsible for cleaning the airways from inhaled particles. Human airway epithelial cilia appear to have a slow constitutive rate of beating, driven by inherent and spontaneous dynein ATPase activity. Additionally, cilia can increase their beating frequency by activation of several different control mechanisms. One of these controllers is calcium. Its intracellular concentration is regulated by purinergic and acetylcholine receptors. Besides the rate regulatory effect of calcium on ciliary beat, calcium is also involved in synchronizing the beat among cilia of one single cell as well as between cilia on different cells. This article gives an overview of the complex effects of calcium on the beating of motile cilia in the airways.
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12
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Abstract
A thin layer of airway surface liquid (ASL) lines the entire surface of the lung and is the first point of contact between the lung and the environment. Surfactants contained within this layer are secreted in the alveolar region and are required to maintain a low surface tension and to prevent alveolar collapse. Mucins are secreted into the ASL throughout the respiratory tract and serve to intercept inhaled pathogens, allergens and toxins. Their removal by mucociliary clearance (MCC) is facilitated by cilia beating and hydration of the ASL by active ion transport. Throughout the lung, secretion, ion transport and cilia beating are under purinergic control. Pulmonary epithelia release ATP into the ASL which acts in an autocrine fashion on P2Y(2) (ATP) receptors. The enzymatic network describes in Chap. 2 then mounts a secondary wave of signaling by surface conversion of ATP into adenosine (ADO), which induces A(2B) (ADO) receptor-mediated responses. This chapter offers a comprehensive description of MCC and the extensive ramifications of the purinergic signaling network on pulmonary surfaces.
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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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14
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Choi LJ, Jenikova G, Hanson E, Spehlmann ME, Boehling NS, Kirstein SL, Bundey RA, Smith JR, Insel PA, Eckmann L. Coordinate down-regulation of adenylyl cyclase isoforms and the stimulatory G protein (G(s)) in intestinal epithelial cell differentiation. J Biol Chem 2010; 285:12504-11. [PMID: 20157112 DOI: 10.1074/jbc.m109.059741] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The intestinal epithelium is dynamic, with proliferation of undifferentiated crypt cells balanced by terminal differentiation and cell death at the colon surface or small intestinal villus tips. Cyclic AMP, induced by agonists such as prostaglandin E(2) and vasoactive intestinal polypeptide, promotes proliferation and ion secretion and suppresses apoptosis in intestinal epithelial cells. Here, we show that cell differentiation in a model intestinal epithelium leads to attenuation of cAMP production in response to G protein-coupled receptor and receptor-independent agonists. Concomitantly, key components of the cAMP cascade, the alpha subunit of the stimulatory G protein, G(s), and adenylyl cyclase (AC) isoforms 3, 4, 6, and 7 are down-regulated. By contrast, AC1, AC2, AC8, and AC9, and the receptors for prostaglandin E(2) and vasoactive intestinal polypeptide, are not expressed or not affected by differentiation. We confirmed key findings in normal murine colon epithelium, in which the major AC isoforms and G(s)alpha are markedly down-regulated in differentiated surface cells. Suppression of AC isoforms and G(s)alpha is functionally important, because their constitutive expression completely reverses differentiation-induced cAMP attenuation. Thus, down-regulation of AC isoforms and G(s)alpha is an integral part of the intestinal epithelial differentiation program, perhaps serving to release cells from cAMP-promoted anti-apoptosis as a prerequisite for cell death upon terminal differentiation.
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Affiliation(s)
- Lillian J Choi
- Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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Ye Y, Hu SJ, Li L. Inhibition of farnesylpyrophosphate synthase prevents angiotensin II-induced hypertrophic responses in rat neonatal cardiomyocytes: involvement of the RhoA/Rho kinase pathway. FEBS Lett 2009; 583:2997-3003. [PMID: 19716825 DOI: 10.1016/j.febslet.2009.08.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 07/22/2009] [Accepted: 08/22/2009] [Indexed: 01/10/2023]
Abstract
The RhoA/Rho-kinase (ROCK) pathway is involved in angiotensin (Ang) II-induced cardiac hypertrophy. However, it is still unclear whether inhibition of farnesylpyrophosphate (FPP) synthase can attenuate Ang II-induced hypertrophic responses, and whether it involves the RhoA/ROCK pathway. The anti-hypertrophic effects of inhibition of FPP synthase with alendronate in Ang II-cultured neonatal cardiomyocytes were partially reversed by geranylgeranyol (GGOH) and were mimicked by GGTI-286, a geranylgeranyl transferase-I inhibitor, C3 exoenzyme, an inhibitor of Rho, or Y-27632, an inhibitor of ROCK. Pull-down assay showed alendronate reduced-active RhoA by Ang II was also partially antagonized by GGOH. This study revealed that the inhibition of FPP synthase by alendronate reduces RhoA activation by diminishing geranylgeranylation which prevents Ang II-induced hypertrophic responses in neonatal cardiomyocytes.
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Affiliation(s)
- Yang Ye
- Institute of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, #79 Qing-Chun Road, Hangzhou 310003, PR China.
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Efficient mucociliary transport relies on efficient regulation of ciliary beating. Respir Physiol Neurobiol 2008; 163:202-7. [PMID: 18586580 DOI: 10.1016/j.resp.2008.05.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 11/22/2022]
Abstract
The respiratory mucociliary epithelium is a synchronized and highly effective waste-disposal system. It uses mucus as a vehicle, driven by beating cilia, to transport unwanted particles, trapped in the mucus, away from the respiratory system. The ciliary machinery can function in at least two different modes: a low rate of beating that requires only ATP, and a high rate of beating regulated by second messengers. The mucus propelling velocity is linearly dependent on ciliary beat frequency (CBF). The linear dependence implies that a substantial increase in transport efficiency requires an equally substantial rise in CBF. The ability to enhance beating in response to various physiological cues is a hallmark of mucociliary cells. An intricate signaling network controls ciliary activity, which relies on interplay between calcium and cyclic nucleotide pathways.
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