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Romero MJ, Yue Q, Singla B, Hamacher J, Sridhar S, Moseley AS, Song C, Mraheil MA, Fischer B, Zeitlinger M, Chakraborty T, Fulton D, Gan L, Annex BH, Csanyi G, Eaton DC, Lucas R. Direct endothelial ENaC activation mitigates vasculopathy induced by SARS-CoV2 spike protein. Front Immunol 2023; 14:1241448. [PMID: 37638055 PMCID: PMC10449264 DOI: 10.3389/fimmu.2023.1241448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 07/25/2023] [Indexed: 08/29/2023] Open
Abstract
Introduction Although both COVID-19 and non-COVID-19 ARDS can be accompanied by significantly increased levels of circulating cytokines, the former significantly differs from the latter by its higher vasculopathy, characterized by increased oxidative stress and coagulopathy in lung capillaries. This points towards the existence of SARS-CoV2-specific factors and mechanisms that can sensitize the endothelium towards becoming dysfunctional. Although the virus is rarely detected within endothelial cells or in the circulation, the S1 subunit of its spike protein, which contains the receptor binding domain (RBD) for human ACE2 (hACE2), can be detected in plasma from COVID-19 patients and its levels correlate with disease severity. It remains obscure how the SARS-CoV2 RBD exerts its deleterious actions in lung endothelium and whether there are mechanisms to mitigate this. Methods In this study, we use a combination of in vitro studies in RBD-treated human lung microvascular endothelial cells (HL-MVEC), including electrophysiology, barrier function, oxidative stress and human ACE2 (hACE2) surface protein expression measurements with in vivo studies in transgenic mice globally expressing human ACE2 and injected with RBD. Results We show that SARS-CoV2 RBD impairs endothelial ENaC activity, reduces surface hACE2 expression and increases reactive oxygen species (ROS) and tissue factor (TF) generation in monolayers of HL-MVEC, as such promoting barrier dysfunction and coagulopathy. The TNF-derived TIP peptide (a.k.a. solnatide, AP301) -which directly activates ENaC upon binding to its a subunit- can override RBD-induced impairment of ENaC function and hACE2 expression, mitigates ROS and TF generation and restores barrier function in HL-MVEC monolayers. In correlation with the increased mortality observed in COVID-19 patients co-infected with S. pneumoniae, compared to subjects solely infected with SARS-CoV2, we observe that prior intraperitoneal RBD treatment in transgenic mice globally expressing hACE2 significantly increases fibrin deposition and capillary leak upon intratracheal instillation of S. pneumoniae and that this is mitigated by TIP peptide treatment.
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Affiliation(s)
- Maritza J. Romero
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Qian Yue
- Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
| | - Bhupesh Singla
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Jürg Hamacher
- Pneumology, Clinic for General Internal Medicine, Lindenhofspital, Bern, Switzerland
- Lungen-und Atmungsstiftung, Bern, Switzerland
- Medical Clinic V—Pneumology, Allergology, Intensive Care Medicine, and Environmental Medicine, Faculty of Medicine, Saarland University, University Medical Centre of the Saarland, Homburg, Germany
| | - Supriya Sridhar
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Auriel S. Moseley
- Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
| | - Chang Song
- Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
| | - Mobarak A. Mraheil
- Institute for Medical Microbiology, German Centre for Infection Giessen-Marburg-Langen Site, Faculty of Medicine, Justus-Liebig University, Giessen, Germany
| | | | - Markus Zeitlinger
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Trinad Chakraborty
- Institute for Medical Microbiology, German Centre for Infection Giessen-Marburg-Langen Site, Faculty of Medicine, Justus-Liebig University, Giessen, Germany
| | - David Fulton
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Lin Gan
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Brian H. Annex
- Department of Medicine, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Gabor Csanyi
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, United States
| | - Douglas C. Eaton
- Department of Medicine, School of Medicine, Emory University, Atlanta, GA, United States
| | - Rudolf Lucas
- Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Department of Pharmacology and Toxicology, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Department of Medicine, Medical College of Georgia at Augusta University, Augusta, GA, United States
- Division of Pulmonary and Critical Care Medicine, Medical College of Georgia at Augusta University, Augusta, GA, United States
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Shabbir W, Susan Yang KH, Dogar AM, Isaev D, Oz M. Probing the Ubiquitination-Mediated Function of Epithelial Sodium Channel in A549 Cells. Curr Mol Pharmacol 2023; 16:411-418. [PMID: 35894469 DOI: 10.2174/1874467215666220726112002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/25/2022] [Accepted: 05/07/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND The activity of the amiloride-sensitive epithelial sodium channel (ENaC) in the tight epithelia of the lung is regulated by proteolytic activation and ubiquitination. Pathophysiology of lung diseases is directly related to changes in one or both of these mechanisms. METHODS In this study, we investigated the impact of ubiquitination and cathepsin-mediated proteolytic activation mechanisms on the functional regulation of ENaC in lung cancer A549 cells using the patch-clamp technique. RESULTS Our findings suggest that inhibiting the proteasome (polyubiquitination) with MG132 improves ENaC activity, whereas altering the pH of the lysosome (monoubiquitination inhibition) with NH4Cl has no effect on ENaC activity. In A549 cells, inhibition of cathepsin B (CSTB) decreased the ENaC current, open probabilities (NPo and Po), and the number of active channels. CONCLUSION These findings delineate novel modes of ENaC degradation and proteolytic activation of functional channels in A549 cells. Our findings indicate that both proteolytic activation and ubiquitination of ENaC significantly affect channel function and add new insights into the endogenous ENaC processing which might help to further understand the pathophysiology of the lung disease.
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Affiliation(s)
- Waheed Shabbir
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Keun-Hang Susan Yang
- Department of Biological Sciences, Schmid College of Science and Technology, Chapman University, One University Drive, Orange, CA 92866, USA
| | - Afzal M Dogar
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Dmytro Isaev
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kyiv, Ukraine
| | - Murat Oz
- Department of Pharmacology and Therapeutics, Faculty of Pharmacy, Kuwait University, Safat, 13110, Kuwait
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Diakov A, Nesterov V, Dahlmann A, Korbmacher C. Two adjacent phosphorylation sites in the C-terminus of the channel's α-subunit have opposing effects on epithelial sodium channel (ENaC) activity. Pflugers Arch 2022; 474:681-697. [PMID: 35525869 PMCID: PMC9192390 DOI: 10.1007/s00424-022-02693-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 04/25/2022] [Indexed: 02/07/2023]
Abstract
How phosphorylation of the epithelial sodium channel (ENaC) contributes to its regulation is incompletely understood. Previously, we demonstrated that in outside-out patches ENaC activation by serum- and glucocorticoid-inducible kinase isoform 1 (SGK1) was abolished by mutating a serine residue in a putative SGK1 consensus motif RXRXX(S/T) in the channel’s α-subunit (S621 in rat). Interestingly, this serine residue is followed by a highly conserved proline residue rather than by a hydrophobic amino acid thought to be required for a functional SGK1 consensus motif according to invitro data. This suggests that this serine residue is a potential phosphorylation site for the dual-specificity tyrosine phosphorylated and regulated kinase 2 (DYRK2), a prototypical proline-directed kinase. Its phosphorylation may prime a highly conserved preceding serine residue (S617 in rat) to be phosphorylated by glycogen synthase kinase 3 β (GSK3β). Therefore, we investigated the effect of DYRK2 on ENaC activity in outside-out patches of Xenopus laevis oocytes heterologously expressing rat ENaC. DYRK2 included in the pipette solution significantly increased ENaC activity. In contrast, GSK3β had an inhibitory effect. Replacing S621 in αENaC with alanine (S621A) abolished the effects of both kinases. A S617A mutation reduced the inhibitory effect of GKS3β but did not prevent ENaC activation by DYRK2. Our findings suggest that phosphorylation of S621 activates ENaC and primes S617 for subsequent phosphorylation by GSK3β resulting in channel inhibition. In proof-of-concept experiments, we demonstrated that DYRK2 can also stimulate ENaC currents in microdissected mouse distal nephron, whereas GSK3β inhibits the currents.
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Affiliation(s)
- Alexei Diakov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany
| | - Anke Dahlmann
- Medizinische Klinik 4 - Nephrologie und Hypertensiologie, Universitätsklinikum Erlangen, Ulmenweg 18, 91054, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstr, 6, 91054, Erlangen, Germany.
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Blaconà G, Raso R, Castellani S, Pierandrei S, Del Porto P, Ferraguti G, Ascenzioni F, Conese M, Lucarelli M. Downregulation of epithelial sodium channel (ENaC) activity in cystic fibrosis cells by epigenetic targeting. Cell Mol Life Sci 2022; 79:257. [PMID: 35462606 PMCID: PMC9035428 DOI: 10.1007/s00018-022-04190-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 01/28/2022] [Accepted: 02/02/2022] [Indexed: 12/31/2022]
Abstract
The pathogenic mechanism of cystic fibrosis (CF) includes the functional interaction of the cystic fibrosis transmembrane conductance regulator (CFTR) protein with the epithelial sodium channel (ENaC). The reduction of ENaC activity may constitute a therapeutic option for CF. This hypothesis was evaluated using drugs that target the protease-dependent activation of the ENaC channel and the transcriptional activity of its coding genes. To this aim we used: camostat, a protease inhibitor; S-adenosyl methionine (SAM), showed to induce DNA hypermethylation; curcumin, known to produce chromatin condensation. SAM and camostat are drugs already clinically used in other pathologies, while curcumin is a common dietary compound. The experimental systems used were CF and non-CF immortalized human bronchial epithelial cell lines as well as human bronchial primary epithelial cells. ENaC activity and SCNN1A, SCNN1B and SCNN1G gene expression were analyzed, in addition to SCNN1B promoter methylation. In both immortalized and primary cells, the inhibition of extracellular peptidases and the epigenetic manipulations reduced ENaC activity. Notably, the reduction in primary cells was much more effective. The SCNN1B appeared to be the best target to reduce ENaC activity, in respect to SCNN1A and SCNN1G. Indeed, SAM treatment resulted to be effective in inducing hypermethylation of SCNN1B gene promoter and in lowering its expression. Importantly, CFTR expression was unaffected, or even upregulated, after treatments. These results open the possibility of CF patients’ treatment by epigenetic targeting.
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Affiliation(s)
- Giovanna Blaconà
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Roberto Raso
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Stefano Castellani
- Department of Biomedical Sciences and Human Oncology, University of Bari, Bari, Italy
| | - Silvia Pierandrei
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Paola Del Porto
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Giampiero Ferraguti
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Fiorentina Ascenzioni
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Massimo Conese
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy.
| | - Marco Lucarelli
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy. .,Pasteur Institute, Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy.
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Pearce D, Manis AD, Nesterov V, Korbmacher C. Regulation of distal tubule sodium transport: mechanisms and roles in homeostasis and pathophysiology. Pflugers Arch 2022; 474:869-884. [PMID: 35895103 PMCID: PMC9338908 DOI: 10.1007/s00424-022-02732-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 02/03/2023]
Abstract
Regulated Na+ transport in the distal nephron is of fundamental importance to fluid and electrolyte homeostasis. Further upstream, Na+ is the principal driver of secondary active transport of numerous organic and inorganic solutes. In the distal nephron, Na+ continues to play a central role in controlling the body levels and concentrations of a more select group of ions, including K+, Ca++, Mg++, Cl-, and HCO3-, as well as water. Also, of paramount importance are transport mechanisms aimed at controlling the total level of Na+ itself in the body, as well as its concentrations in intracellular and extracellular compartments. Over the last several decades, the transporters involved in moving Na+ in the distal nephron, and directly or indirectly coupling its movement to that of other ions have been identified, and their interrelationships brought into focus. Just as importantly, the signaling systems and their components-kinases, ubiquitin ligases, phosphatases, transcription factors, and others-have also been identified and many of their actions elucidated. This review will touch on selected aspects of ion transport regulation, and its impact on fluid and electrolyte homeostasis. A particular focus will be on emerging evidence for site-specific regulation of the epithelial sodium channel (ENaC) and its role in both Na+ and K+ homeostasis. In this context, the critical regulatory roles of aldosterone, the mineralocorticoid receptor (MR), and the kinases SGK1 and mTORC2 will be highlighted. This includes a discussion of the newly established concept that local K+ concentrations are involved in the reciprocal regulation of Na+-Cl- cotransporter (NCC) and ENaC activity to adjust renal K+ secretion to dietary intake.
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Affiliation(s)
- David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Anna D. Manis
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
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Artunc F, Bohnert BN, Schneider JC, Staudner T, Sure F, Ilyaskin AV, Wörn M, Essigke D, Janessa A, Nielsen NV, Birkenfeld AL, Etscheid M, Haerteis S, Korbmacher C, Kanse SM. Proteolytic activation of the epithelial sodium channel (ENaC) by factor VII activating protease (FSAP) and its relevance for sodium retention in nephrotic mice. Pflugers Arch 2021; 474:217-229. [PMID: 34870751 PMCID: PMC8766372 DOI: 10.1007/s00424-021-02639-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/05/2021] [Accepted: 10/18/2021] [Indexed: 12/18/2022]
Abstract
Proteolytic activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases is thought to contribute to renal sodium retention in nephrotic syndrome. However, the identity of the responsible proteases remains elusive. This study evaluated factor VII activating protease (FSAP) as a candidate in this context. We analyzed FSAP in the urine of patients with nephrotic syndrome and nephrotic mice and investigated its ability to activate human ENaC expressed in Xenopus laevis oocytes. Moreover, we studied sodium retention in FSAP-deficient mice (Habp2−/−) with experimental nephrotic syndrome induced by doxorubicin. In urine samples from nephrotic humans, high concentrations of FSAP were detected both as zymogen and in its active state. Recombinant serine protease domain of FSAP stimulated ENaC-mediated whole-cell currents in a time- and concentration-dependent manner. Mutating the putative prostasin cleavage site in γ-ENaC (γRKRK178AAAA) prevented channel stimulation by the serine protease domain of FSAP. In a mouse model for nephrotic syndrome, active FSAP was present in nephrotic urine of Habp2+/+ but not of Habp2−/− mice. However, Habp2−/− mice were not protected from sodium retention compared to nephrotic Habp2+/+ mice. Western blot analysis revealed that in nephrotic Habp2−/− mice, proteolytic cleavage of α- and γ-ENaC was similar to that in nephrotic Habp2+/+ animals. In conclusion, active FSAP is excreted in the urine of nephrotic patients and mice and activates ENaC in vitro involving the putative prostasin cleavage site of γ-ENaC. However, endogenous FSAP is not essential for sodium retention in nephrotic mice.
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Affiliation(s)
- Ferruh Artunc
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany. .,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany. .,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany.
| | - Bernhard N Bohnert
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | - Jonas C Schneider
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Tobias Staudner
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Florian Sure
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Alexandr V Ilyaskin
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Matthias Wörn
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Daniel Essigke
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | - Andrea Janessa
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany
| | - Nis V Nielsen
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Andreas L Birkenfeld
- Department of Internal Medicine, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, Tubingen, Germany.,Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University Tübingen, Tubingen, Germany.,German Center for Diabetes Research (DZD) at the University Tübingen, Tubingen, Germany
| | | | - Silke Haerteis
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.,Institute of Anatomy, University of Regensburg, Regensburg, Germany
| | - Christoph Korbmacher
- Institute of Cellular and Molecular Physiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Sandip M Kanse
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Ware AW, Harris JJ, Slatter TL, Cunliffe HE, McDonald FJ. The epithelial sodium channel has a role in breast cancer cell proliferation. Breast Cancer Res Treat 2021; 187:31-43. [PMID: 33630195 DOI: 10.1007/s10549-021-06133-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 02/05/2021] [Indexed: 01/22/2023]
Abstract
PURPOSE Breast cancer is the most common cancer affecting women worldwide with half a million associated deaths annually. Despite a huge global effort, the pathways of breast cancer progression are not fully elucidated. Ion channels have recently emerged as novel regulators of cancer cell proliferation and metastasis. The epithelial sodium channel, ENaC, made up of α, β and γ subunits is well known for its role in Na+ reabsorption in epithelia, but a number of novel roles for ENaC have been described, including potential roles in cancer. A role for ENaC in breast cancer, however, has yet to be described. Therefore, the effects of ENaC level and activity on breast cancer proliferation were investigated. METHODS Through the publicly available SCAN-B dataset associations between αENaC mRNA expression and breast cancer subtypes, proliferation markers and epithelial-mesenchymal transition markers (EMT) were assessed. αENaC expression, through overexpression or siRNA-mediated knockdown, and activity, through the ENaC-specific inhibitor amiloride, were altered in MCF7, T47D, BT549, and MDAMB231 breast cancer cells. MTT and EdU cell proliferation assays were used to determine the effect of these manipulations on breast cancer cell proliferation. RESULTS High αENaC mRNA expression was associated with less aggressive and less proliferative breast cancer subtypes and with reduced expression of proliferation markers. Decreased αENaC expression or activity, in the mesenchymal breast cancer cell lines BT549 and MDAMB231, increased breast cancer cell proliferation. Conversely, increased αENaC expression decreased breast cancer cell proliferation. CONCLUSION αENaC expression is associated with a poor prognosis in breast cancer and is a novel regulator of breast cancer cell proliferation. Taken together, these results identify ENaC as a potential future therapeutic target.
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Affiliation(s)
- Adam W Ware
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Joshua J Harris
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Tania L Slatter
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Heather E Cunliffe
- Department of Pathology, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Fiona J McDonald
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.
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Rauh R, Frost F, Korbmacher C. Effects of syntaxins 2, 3, and 4 on rat and human epithelial sodium channel (ENaC) in Xenopus laevis oocytes. Pflugers Arch 2020; 472:461-71. [PMID: 32221667 DOI: 10.1007/s00424-020-02365-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 01/20/2023]
Abstract
Syntaxins are SNARE proteins and may play a role in epithelial sodium channel (ENaC) trafficking. The aim of the present study was to investigate the effects of syntaxin 2 (STX2), syntaxin 3 (STX3), and syntaxin 4 (STX4) on rat (rENaC) and human ENaC (hENaC). Co-expression of rENaC and STX3 or STX4 in Xenopus laevis oocytes increased amiloride-sensitive whole-cell currents (ΔIami) on average by 50% and 135%, respectively, compared to oocytes expressing rENaC alone. In contrast, STX2 had no significant effect on rENaC. Similar to its effect on rENaC, STX3 stimulated hENaC by 48%. In contrast, STX2 and STX4 inhibited hENaC by 51% and 44%, respectively. Using rENaC carrying a FLAG tag in the extracellular loop of the β-subunit, we demonstrated that the stimulatory effects of STX3 and STX4 on ΔIami were associated with an increased expression of the channel at the cell surface. Co-expression of STX3 or STX4 did not significantly alter the degree of proteolytic channel activation by chymotrypsin. STX3 had no effect on the inhibition of rENaC by brefeldin A, and the stimulatory effect of STX3 was preserved in the presence of dominant negative Rab11. This indicates that the stimulatory effect of STX3 is not mediated by inhibiting channel retrieval or by stimulating fusion of recycling endosomes. Our results suggest that the effects of syntaxins on ENaC are isoform and species dependent. Furthermore, our results demonstrate that STX3 increases ENaC expression at the cell surface, probably by enhancing insertion of vesicles carrying newly synthesized channels.
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Migneault F, Gagnon F, Pascariu M, Laperle J, Roy A, Dagenais A, Berthiaume Y. Post-Transcriptional Modulation of aENaC mRNA in Alveolar Epithelial Cells: Involvement of its 3' Untranslated Region. Cell Physiol Biochem 2019; 52:984-1002. [PMID: 30977984 DOI: 10.33594/000000068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 02/25/2019] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS The epithelial sodium channel (ENaC) expressed in alveolar epithelial cells plays a major role in lung liquid clearance at birth and lung edema resorption in adulthood. We showed previously that αENaC mRNA expression is downregulated in part via posttranscriptional regulation of mRNA stability. In the present work, the role of the αENaC 3' untranslated region (3'UTR) in the regulation of mRNA stability was studied further. METHODS Quantitative reverse transcription PCR (qRT-PCR) was performed to investigate the expression of αENaC in alveolar epithelial cells. The role of the αENaC 3'UTR was evaluated through sequential deletions. RNA affinity chromatography and mass spectrometry were achieved to investigate the nature of the proteins that could bind this sequence. The function of these proteins was assessed through knockdown and overexpression in vitro. RESULTS First, we found that αENaC mRNA half-life was much shorter than expected when using a transcriptionally controlled plasmid expression system compared to Actinomycin D treatment. Sequential deletions of the αENaC 3'UTR revealed that the αENaC 3'UTR plays an important role in the modulation of αENaC mRNA stability, and that there is a complex stabilizing and destabilizing interplay between different regions of the 3'UTR that modulate this process. Finally, we identified RNA-binding proteins that interact with the αENaC 3'UTR and showed that Dhx36 and Tial1 are involved in the decrease in αENaC mRNA stability via the proximal region of its 3'UTR. CONCLUSION Taken together, these findings indicate that the αENaC 3'UTR plays an important role in modulating transcript levels, and Dhx36 and Tial1 seem to be involved in posttranscriptional regulation of αENaC expression in alveolar epithelial cells.
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Affiliation(s)
- Francis Migneault
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada.,Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada,
| | - Frédéric Gagnon
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada.,Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Mihai Pascariu
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Jonathan Laperle
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Antoine Roy
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - André Dagenais
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada
| | - Yves Berthiaume
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC, Canada.,Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
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10
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Richard C, Shabbir W, Ferraro P, Massé C, Berthiaume Y. Alveolar liquid clearance in lung injury: Evaluation of the impairment of the β 2-adrenergic agonist response in an ischemia-reperfusion lung injury model. Respir Physiol Neurobiol 2018; 259:104-110. [PMID: 30171906 DOI: 10.1016/j.resp.2018.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 07/27/2018] [Accepted: 08/27/2018] [Indexed: 01/05/2023]
Abstract
While alveolar liquid clearance (ALC) mediated by the β2-adrenergic receptor (β2-AR) plays an important role in lung edema resolution in certain models of lung injury, in more severe lung injury models, this response might disappear. Indeed, we have shown that in an ischemia-reperfusion-induced lung injury model, β2-agonists do not enhance ALC. The objective of this study was to determine if downregulation of the β2-AR could explain the lack of response to β2-agonists in this lung injury model. In an in vivo canine model of lung transplantation, we observed no change in β2-AR concentration or affinity in the injured transplanted lungs compared to the native lungs. Furthermore, we could not enhance ALC in transplanted lungs with dcAMP + aminophylline, a treatment that bypasses the β2-adrenergic receptor and is known to stimulate ALC in normal lungs. However, transplantation decreased αENaC expression in the lungs by 50%. We conclude that the lack of response to β2-agonists in ischemia-reperfusion-induced lung injury is not associated with significant downregulation of the β2-adrenergic receptors but is attributable to decreased expression of the ENaC channel, which is essential for sodium transport and alveolar liquid clearance in the lung.
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Affiliation(s)
- Chloé Richard
- Centre de recherche, Centre hospitalier de l'université de Montréal (CHUM), Canada
| | - Waheed Shabbir
- Institute of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Pasquale Ferraro
- Centre de recherche, Centre hospitalier de l'université de Montréal (CHUM), Canada; Département de chirurgie, Université de Montréal, Montréal, Québec, Canada
| | - Chantal Massé
- Centre de recherche, Centre hospitalier de l'université de Montréal (CHUM), Canada; Institut de recherches cliniques de Montréal (IRCM), Montréal, Quebec, Canada
| | - Yves Berthiaume
- Centre de recherche, Centre hospitalier de l'université de Montréal (CHUM), Canada; Département de médecine, Université de Montréal, Montréal, Québec, Canada; Institut de recherches cliniques de Montréal (IRCM), Montréal, Quebec, Canada.
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11
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Aziz DA, Memon F, Rahman A, Ali M. Liddle's Syndrome. J Ayub Med Coll Abbottabad 2016; 28:809-811. [PMID: 28586600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hypertension in paediatric age group is commonly secondary to a known cause. It is crucial to identify the cause of hypertension and treat it before development of any associated complications to prevent morbidity and mortality. Paediatric Hypertension is one of the important clinical finding in a child with certain clinical syndrome. We are presenting a case of a 10 month old child presenting with hypertension and hypokalaemia, after excluding all identifiable causes and her positive response to therapy, that is amiloride, along with supportive biochemical data she was diagnosed as a case of monogenic type of hypertension known as Liddle's syndrome.
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Affiliation(s)
- Danish Abdul Aziz
- Department of Paediatrics, Aga Khan University Hospital Karachi, Pakistan
| | - Fozia Memon
- Department of Paediatrics, Aga Khan University Hospital Karachi, Pakistan
| | - Arshalooz Rahman
- Department of Paediatrics, Aga Khan University Hospital Karachi, Pakistan
| | - Madiha Ali
- Department of Paediatrics, Aga Khan University Hospital Karachi, Pakistan
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12
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Amara S, Ivy MT, Myles EL, Tiriveedhi V. Sodium channel γENaC mediates IL-17 synergized high salt induced inflammatory stress in breast cancer cells. Cell Immunol 2015; 302:1-10. [PMID: 26723502 DOI: 10.1016/j.cellimm.2015.12.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 01/03/2023]
Abstract
Chronic inflammation is known to play a critical role in the development of cancer. Recent evidence suggests that high salt in the tissue microenvironment induces chronic inflammatory milieu. In this report, using three breast cancer-related cell lines, we determined the molecular basis of the potential synergistic inflammatory effect of sodium chloride (NaCl) with interleukin-17 (IL-17). Combined treatment of high NaCl (0.15M) with sub-effective IL-17 (0.1 nM) induced enhanced growth in breast cancer cells along with activation of reactive nitrogen and oxygen (RNS/ROS) species known to promote cancer. Similar effect was not observed with equi-molar mannitol. This enhanced of ROS/RNS activity correlates with upregulation of γENaC an inflammatory sodium channel. The similar culture conditions have also induced expression of pro-inflammatory cytokines such as IL-6, TNFα etc. Taken together, these data suggest that high NaCl in the cellular microenvironment induces a γENaC mediated chronic inflammatory response with a potential pro-carcinogenic effect.
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Affiliation(s)
- Suneetha Amara
- Department of Medicine, Mercy Hospital, St Louis, MO, USA
| | - Michael T Ivy
- Department of Biological Sciences, Tennessee State University, Nashville, TN, USA
| | - Elbert L Myles
- Department of Biological Sciences, Tennessee State University, Nashville, TN, USA
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Park MK, Chae SW, Kim HB, Cho JG, Song JJ. Middle ear inflammation of rat induced by urban particles. Int J Pediatr Otorhinolaryngol 2014; 78:2193-7. [PMID: 25458159 DOI: 10.1016/j.ijporl.2014.10.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/04/2014] [Accepted: 10/10/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the histologic change of middle ear mucosa and the expression levels of epithelial sodium channel (ENaC) subunits and mucin production genes, after the injection of urban particulate matter (UPM) into the middle ear cavity of rats. METHODS Fifty pathogen-free, male Sprague Dawley rats were assigned to the study. Transtympanic injection of UPM solution (300μg/ml, 50μl) was made into the middle ear cavity of rats. Rats were sacrificed at day 1 (group1); day 3 (group2); day 5 (group3); and day 14 (group4) after the procedure. The expression levels of ENaC subunits (α, β and γ) and mucin producing genes (MUC5AC and MUC5B) were analyzed using semi-quantitative real-time reverse transcriptase-polymerase chain reaction. Thickness of middle ear mucosa was measured and analyzed. RESULT After transtympanic injection, the thickness of middle ear mucosa increased significantly on day 1, 3 and 5 (p<0.05) and was normalized on day 14, compared to the control group. Inflammatory changes observed in the middle ear mucosa were subepithelial widening, inflammatory cell infiltration and vascular space widening on day 1, 3 and 5. These changes had reverted to normal on day 14. The level of ENaC-α expression decreased 0.60 fold on day 1 (p<0.05), but was normalized thereafter. The level of ENaC-β and γ decreased 0.39 and 0.27 fold, respectively, on day 1, was normalized on days 3 and 5, and increased 2.30 and 2.47 fold on day 14, respectively (p<0.05). The level of MUC5AC expression increased 1.97-fold on day 1 (p<0.05) and 2.58-fold on day 5 (p<0.05), but was normalized on day 14. The level of MUC5B expression increased 5.4-fold on day 1, 3.14-fold on day 3, 3.85-fold on day 5, and 2.46-fold on day 14, respectively (p<0.05). CONCLUSION Transtympanic injection of UPM solution into the middle ear cavity of rat induced a characteristic inflammatory response and altered gene expression related with inflammation and mucin production. These findings provide a useful clue for the understanding of how air pollutants, particularly UPM, contribute to the development of otitis media.
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Affiliation(s)
- Moo Kyun Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul, South Korea
| | - Sung Won Chae
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Hee-Bok Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Jae Gu Cho
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea.
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Goel P, Manning JA, Kumar S. NEDD4-2 (NEDD4L): the ubiquitin ligase for multiple membrane proteins. Gene 2014; 557:1-10. [PMID: 25433090 DOI: 10.1016/j.gene.2014.11.051] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/14/2014] [Accepted: 11/21/2014] [Indexed: 12/20/2022]
Abstract
NEDD4-2 (also known as NEDD4L, neural precursor cell expressed developmentally down-regulated 4-like) is a ubiquitin protein ligase of the Nedd4 family which is known to bind and regulate a number of membrane proteins to aid in their internalization and turnover. Several of the NEDD4-2 substrates include ion channels, such as the epithelial and voltage-gated sodium channels. Given the critical function of NEDD4-2 in regulating membrane proteins, this ligase is essential for the maintenance of cellular homeostasis. In this article we review the biology and function of this important ubiquitin-protein ligase and discuss its pathophysiological significance.
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Affiliation(s)
- Pranay Goel
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia; Department of Medicine, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Jantina A Manning
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia; Department of Medicine, The University of Adelaide, Adelaide, SA 5005, Australia.
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Cerecedo D, Martínez-Vieyra I, Alonso-Rangel L, Benítez-Cardoza C, Ortega A. Epithelial sodium channel modulates platelet collagen activation. Eur J Cell Biol 2014; 93:127-36. [PMID: 24679405 DOI: 10.1016/j.ejcb.2014.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 01/30/2014] [Accepted: 02/24/2014] [Indexed: 12/14/2022] Open
Abstract
Activated platelets adhere to the exposed subendothelial extracellular matrix and undergo a rapid cytoskeletal rearrangement resulting in shape change and release of their intracellular dense and alpha granule contents to avoid hemorrhage. A central step in this process is the elevation of the intracellular Ca(2+) concentration through its release from intracellular stores and on throughout its influx from the extracellular space. The Epithelial sodium channel (ENaC) is a highly selective Na(+) channel involved in mechanosensation, nociception, fluid volume homeostasis, and control of arterial blood pressure. The present study describes the expression, distribution, and participation of ENaC in platelet migration and granule secretion using pharmacological inhibition with amiloride. Our biochemical and confocal analysis in suspended and adhered platelets suggests that ENaC is associated with Intermediate filaments (IF) and with Dystrophin-associated proteins (DAP) via α-syntrophin and β-dystroglycan. Migration assays, quantification of soluble P-selectin, and serotonin release suggest that ENaC is dispensable for migration and alpha and dense granule secretion, whereas Na(+) influx through this channel is fundamental for platelet collagen activation.
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Affiliation(s)
- Doris Cerecedo
- Laboratorio de Hematobiología, Escuela Nacional de Medicina y Homeopatía (ENMH), Instituto Politécnico Nacional (IPN), Mexico City, Mexico.
| | - Ivette Martínez-Vieyra
- Laboratorio de Hematobiología, Escuela Nacional de Medicina y Homeopatía (ENMH), Instituto Politécnico Nacional (IPN), Mexico City, Mexico
| | - Lea Alonso-Rangel
- Laboratorio de Hematobiología, Escuela Nacional de Medicina y Homeopatía (ENMH), Instituto Politécnico Nacional (IPN), Mexico City, Mexico
| | - Claudia Benítez-Cardoza
- Laboratorio de Bioquímica, Escuela Nacional de Medicina y Homeopatía (ENMH), Instituto Politécnico Nacional (IPN), Mexico City, Mexico
| | - Arturo Ortega
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN (Cinvestav-IPN), Mexico City, Mexico
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Matsubara A, Miyashita T, Inamoto R, Hoshikawa H, Mori N. Cystic fibrosis transmembrane conductance regulator in the endolymphatic sac of the rat. Auris Nasus Larynx 2014; 41:409-12. [PMID: 24598307 DOI: 10.1016/j.anl.2014.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 02/05/2014] [Accepted: 02/07/2014] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Na(+) and Cl(-) are dominant ions in the endolymphatic fluid in the endolymphatic sac and are important for volume regulation in the endolymphatic sac. An epithelial sodium channel (ENaC) and other Na(+) transporters have been identified in the endolymphatic sac epithelia, and they are involved in the regulation of endolymph. Although the presence of Cl(-) channels in the endolymphatic sac epithelia has been speculated, no Cl(-) channels have been identified. In this study, we confirmed the expression of cystic fibrosis transmembrane conductance regulator (CFTR) in the endolymphatic sac by reverse transcriptase polymerase chain reaction (RT-PCR) and by immunohistochemical staining. METHODS Pure mRNA from endolymphatic sac epithelia was prepared using laser capture microdissection (LCM) and examined using RT-PCR. Localization of CFTR and ENaC in the endolymphatic sac was examined using immunohistochemistry. RESULTS mRNA of the CFTR was expressed in the endolymphatic sac. Immunohistochemical analysis showed the expression of the CFTR on apical side of the endolymphatic sac epithelia and co-localization with the ENaC. CONCLUSION RT-PCR and immunohistochemistry were used to identify the expression of CFTR in the endolymphatic sac epithelia, which gives us a clue for understanding Cl(-) transport in the endolymphatic sac. These results suggest a pathway for Cl(-), possibly through interaction with the ENaC, which may regulate the endolymph in the endolymphatic sac.
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Affiliation(s)
- Ai Matsubara
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Japan.
| | - Takenori Miyashita
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Japan
| | - Ryuhei Inamoto
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Japan
| | - Hiroshi Hoshikawa
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Japan
| | - Nozomu Mori
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Japan
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