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Su S, Wahl A, Rugis J, Suresh V, Yule DI, Sneyd J. A mathematical model of ENaC and Slc26a6 regulation by CFTR in salivary gland ducts. Am J Physiol Gastrointest Liver Physiol 2024; 326:G555-G566. [PMID: 38349781 DOI: 10.1152/ajpgi.00168.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/17/2024] [Accepted: 02/06/2024] [Indexed: 02/15/2024]
Abstract
Cystic fibrosis (CF) is a genetic disease caused by the mutations of cystic fibrosis transmembrane conductance regulator (CFTR), the cystic fibrosis transmembrane conductance regulator gene. Cftr is a critical ion channel expressed in the apical membrane of mouse salivary gland striated duct cells. Although Cftr is primarily a Cl- channel, its knockout leads to higher salivary Cl- and Na+ concentrations and lower pH. Mouse experiments show that the activation of Cftr upregulates epithelial Na+ channel (ENaC) protein expression level and Slc26a6 (a 1Cl-:2[Formula: see text] exchanger of the solute carrier family) activity. Experimentally, it is difficult to predict how much the coregulation effects of CFTR contribute to the abnormal Na+, Cl-, and [Formula: see text] concentrations and pH in CF saliva. To address this question, we construct a wild-type mouse salivary gland model and simulate CFTR knockout by altering the expression levels of CFTR, ENaC, and Slc26a6. By reproducing the in vivo and ex vivo final saliva measurements from wild-type and CFTR knockout animals, we obtain computational evidence that ENaC and Slc26a6 activities are downregulated in CFTR knockout in salivary glands.NEW & NOTEWORTHY This paper describes a salivary gland mathematical model simulating the ion exchange between saliva and the salivary gland duct epithelium. The novelty lies in the implementation of CFTR regulating ENaC and Slc26a6 in a CFTR knockout gland. By reproducing the experimental saliva measurements in wild-type and CFTR knockout glands, the model shows that CFTR regulates ENaC and Slc26a6 anion exchanger in salivary glands. The method could be used to understand the various cystic fibrosis phenotypes.
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Affiliation(s)
- Shan Su
- Department of Mathematics, University of Auckland, Auckland, New Zealand
| | - Amanda Wahl
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York, United States
| | - John Rugis
- Department of Mathematics, University of Auckland, Auckland, New Zealand
| | - Vinod Suresh
- Auckland Biomedical Engineering Institute, University of Auckland, Auckland, New Zealand
- Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - David I Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York, United States
| | - James Sneyd
- Department of Mathematics, University of Auckland, Auckland, New Zealand
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2
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Wu M, Chen JH. CFTR dysfunction leads to defective bacterial eradication on cystic fibrosis airways. Front Physiol 2024; 15:1385661. [PMID: 38699141 PMCID: PMC11063615 DOI: 10.3389/fphys.2024.1385661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/04/2024] [Indexed: 05/05/2024] Open
Abstract
Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel by genetic mutations causes the inherited disease cystic fibrosis (CF). CF lung disease that involves multiple disorders of epithelial function likely results from loss of CFTR function as an anion channel conducting chloride and bicarbonate ions and its function as a cellular regulator modulating the activity of membrane and cytosol proteins. In the absence of CFTR activity, abundant mucus accumulation, bacterial infection and inflammation characterize CF airways, in which inflammation-associated tissue remodeling and damage gradually destroys the lung. Deciphering the link between CFTR dysfunction and bacterial infection in CF airways may reveal the pathogenesis of CF lung disease and guide the development of new treatments. Research efforts towards this goal, including high salt, low volume, airway surface liquid acidosis and abnormal mucus hypotheses are critically reviewed.
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Affiliation(s)
| | - Jeng-Haur Chen
- College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang, China
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3
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Brazier F, Cornière N, Picard N, Chambrey R, Eladari D. Pendrin: linking acid base to blood pressure. Pflugers Arch 2024; 476:533-543. [PMID: 38110744 DOI: 10.1007/s00424-023-02897-7] [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: 10/24/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
Pendrin (SLC26A4) is an anion exchanger from the SLC26 transporter family which is mutated in human patients affected by Pendred syndrome, an autosomal recessive disease characterized by sensoneurinal deafness and hypothyroidism. Pendrin is also expressed in the kidney where it mediates the exchange of internal HCO3- for external Cl- at the apical surface of renal type B and non-A non-B-intercalated cells. Studies using pendrin knockout mice have first revealed that pendrin is essential for renal base excretion. However, subsequent studies have demonstrated that pendrin also controls chloride absorption by the distal nephron and that this mechanism is critical for renal NaCl balance. Furthermore, pendrin has been shown to control vascular volume and ultimately blood pressure. This review summarizes the current knowledge about how pendrin is linking renal acid-base regulation to blood pressure control.
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Affiliation(s)
- François Brazier
- Centre de dépistage et de Médecine de précision des Maladies Rénales, Service de Néphrologie, Centre Hospitalier Universitaire Amiens-Picardie, Université de Picardie Jules Verne, F-80000, Amiens, France
| | - Nicolas Cornière
- Centre de dépistage et de Médecine de précision des Maladies Rénales, Service de Néphrologie, Centre Hospitalier Universitaire Amiens-Picardie, Université de Picardie Jules Verne, F-80000, Amiens, France
| | - Nicolas Picard
- Laboratory of Tissue Biology and Therapeutic Engineering, UMR 5305 CNRS, University Lyon 1, Lyon, France
| | - Régine Chambrey
- Paris Cardiovascular Research Center (PARCC), INSERM U970, F-75015, Paris, France
| | - Dominique Eladari
- Centre de dépistage et de Médecine de précision des Maladies Rénales, Service de Néphrologie, Centre Hospitalier Universitaire Amiens-Picardie, Université de Picardie Jules Verne, F-80000, Amiens, France.
- Laboratory of Tissue Biology and Therapeutic Engineering, UMR 5305 CNRS, University Lyon 1, Lyon, France.
- French Clinical Research Infrastructure Network (F-CRIN): INI-CRCT, Vandœuvre-lès-Nancy, France.
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4
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Geertsma ER, Oliver D. SLC26 Anion Transporters. Handb Exp Pharmacol 2024; 283:319-360. [PMID: 37947907 DOI: 10.1007/164_2023_698] [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] [Indexed: 11/12/2023]
Abstract
Solute carrier family 26 (SLC26) is a family of functionally diverse anion transporters found in all kingdoms of life. Anions transported by SLC26 proteins include chloride, bicarbonate, and sulfate, but also small organic dicarboxylates such as fumarate and oxalate. The human genome encodes ten functional homologs, several of which are causally associated with severe human diseases, highlighting their physiological importance. Here, we review novel insights into the structure and function of SLC26 proteins and summarize the physiological relevance of human members.
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Affiliation(s)
- Eric R Geertsma
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, Marburg, Germany.
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Marburg, Giessen, Germany.
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5
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Kang MJ, Ioannou S, Lougheide Q, Dittmar M, Hsu Y, Pastor-Soler NM. The study of intercalated cells using ex vivo techniques: primary cell culture, cell lines, kidney slices, and organoids. Am J Physiol Cell Physiol 2024; 326:C229-C251. [PMID: 37899748 DOI: 10.1152/ajpcell.00479.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 10/23/2023] [Accepted: 10/24/2023] [Indexed: 10/31/2023]
Abstract
This review summarizes methods to study kidney intercalated cell (IC) function ex vivo. While important for acid-base homeostasis, IC dysfunction is often not recognized clinically until it becomes severe. The advantage of using ex vivo techniques is that they allow for the differential evaluation of IC function in controlled environments. Although in vitro kidney tubular perfusion is a classical ex vivo technique to study IC, here we concentrate on primary cell cultures, immortalized cell lines, and ex vivo kidney slices. Ex vivo techniques are useful in evaluating IC signaling pathways that allow rapid responses to extracellular changes in pH, CO2, and bicarbonate (HCO3-). However, these methods for IC work can also be challenging, as cell lines that recapitulate IC do not proliferate easily in culture. Moreover, a "pure" IC population in culture does not necessarily replicate its collecting duct (CD) environment, where ICs are surrounded by the more abundant principal cells (PCs). It is reassuring that many findings obtained in ex vivo IC systems signaling have been largely confirmed in vivo. Some of these newly identified signaling pathways reveal that ICs are important for regulating NaCl reabsorption, thus suggesting new frontiers to target antihypertensive treatments. Moreover, recent single-cell characterization studies of kidney epithelial cells revealed a dual developmental origin of IC, as well as the presence of novel CD cell types with certain IC characteristics. These exciting findings present new opportunities for the study of IC ex vivo and will likely rediscover the importance of available tools in this field.NEW & NOTEWORTHY The study of kidney intercalated cells has been limited by current cell culture and kidney tissue isolation techniques. This review is to be used as a reference to select ex vivo techniques to study intercalated cells. We focused on the use of cell lines and kidney slices as potential useful models to study membrane transport proteins. We also review how novel collecting duct organoids may help better elucidate the role of these intriguing cells.
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Affiliation(s)
- Min Ju Kang
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine of USC, Los Angeles, California, United States
| | - Silvia Ioannou
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine of USC, Los Angeles, California, United States
| | - Quinn Lougheide
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine of USC, Los Angeles, California, United States
| | - Michael Dittmar
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine of USC, Los Angeles, California, United States
| | - Young Hsu
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine of USC, Los Angeles, California, United States
| | - Nuria M Pastor-Soler
- Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine of USC, Los Angeles, California, United States
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6
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Kunzelmann K, Centeio R, Ousingsawat J, Talbi K, Seidler U, Schreiber R. SLC26A9 in airways and intestine: secretion or absorption? Channels (Austin) 2023; 17:2186434. [PMID: 36866602 PMCID: PMC9988340 DOI: 10.1080/19336950.2023.2186434] [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] [Indexed: 03/04/2023] Open
Abstract
SLC26A9 is one out of 11 proteins that belong to the SLC26A family of anion transporters. Apart from expression in the gastrointestinal tract, SLC26A9 is also found in the respiratory system, in male tissues and in the skin. SLC26A9 has gained attention because of its modifier role in the gastrointestinal manifestation of cystic fibrosis (CF). SLC26A9 appears to have an impact on the extent of intestinal obstruction caused by meconium ileus. SLC26A9 supports duodenal bicarbonate secretion, but was assumed to provide a basal Cl- secretory pathway in airways. However, recent results show that basal airway Cl- secretion is due to cystic fibrosis conductance regulator (CFTR), while SLC26A9 may rather secrete HCO3-, thereby maintaining proper airway surface liquid (ASL) pH. Moreover, SLC26A9 does not secrete but probably supports reabsorption of fluid particularly in the alveolar space, which explains early death by neonatal distress in Slc26a9-knockout animals. While the novel SLC26A9 inhibitor S9-A13 helped to unmask the role of SLC26A9 in the airways, it also provided evidence for an additional role in acid secretion by gastric parietal cells. Here we discuss recent data on the function of SLC26A9 in airways and gut, and how S9-A13 may be useful in unraveling the physiological role of SLC26A9.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
- CONTACT Karl Kunzelmann
| | - Raquel Centeio
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Khaoula Talbi
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
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7
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Kunzelmann K, Ousingsawat J, Kraus A, Park JH, Marquardt T, Schreiber R, Buchholz B. Pathogenic Relationships in Cystic Fibrosis and Renal Diseases: CFTR, SLC26A9 and Anoctamins. Int J Mol Sci 2023; 24:13278. [PMID: 37686084 PMCID: PMC10487509 DOI: 10.3390/ijms241713278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/31/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
The Cl--transporting proteins CFTR, SLC26A9, and anoctamin (ANO1; ANO6) appear to have more in common than initially suspected, as they all participate in the pathogenic process and clinical outcomes of airway and renal diseases. In the present review, we will therefore concentrate on recent findings concerning electrolyte transport in the airways and kidneys, and the role of CFTR, SLC26A9, and the anoctamins ANO1 and ANO6. Special emphasis will be placed on cystic fibrosis and asthma, as well as renal alkalosis and polycystic kidney disease. In essence, we will summarize recent evidence indicating that CFTR is the only relevant secretory Cl- channel in airways under basal (nonstimulated) conditions and after stimulation by secretagogues. Information is provided on the expressions of ANO1 and ANO6, which are important for the correct expression and function of CFTR. In addition, there is evidence that the Cl- transporter SLC26A9 expressed in the airways may have a reabsorptive rather than a Cl--secretory function. In the renal collecting ducts, bicarbonate secretion occurs through a synergistic action of CFTR and the Cl-/HCO3- transporter SLC26A4 (pendrin), which is probably supported by ANO1. Finally, in autosomal dominant polycystic kidney disease (ADPKD), the secretory function of CFTR in renal cyst formation may have been overestimated, whereas ANO1 and ANO6 have now been shown to be crucial in ADPKD and therefore represent new pharmacological targets for the treatment of polycystic kidney disease.
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Affiliation(s)
- Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Andre Kraus
- Department of Nephrology and Hypertension, Friedrich Alexander University Erlangen Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
| | - Julien H. Park
- Department of Pediatrics, University Hospital Münster, 48149 Münster, Germany; (J.H.P.); (T.M.)
| | - Thorsten Marquardt
- Department of Pediatrics, University Hospital Münster, 48149 Münster, Germany; (J.H.P.); (T.M.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Björn Buchholz
- Department of Nephrology and Hypertension, Friedrich Alexander University Erlangen Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
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8
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Whittamore JM, Hatch M. Oxalate secretion is stimulated by a cAMP-dependent pathway in the mouse cecum. Pflugers Arch 2023; 475:249-266. [PMID: 36044064 PMCID: PMC9851989 DOI: 10.1007/s00424-022-02742-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/06/2022] [Accepted: 08/18/2022] [Indexed: 02/01/2023]
Abstract
Elevated levels of the intracellular second messenger cAMP can stimulate intestinal oxalate secretion however the membrane transporters responsible are unclear. Oxalate transport by the chloride/bicarbonate (Cl-/HCO3-) exchanger Slc26a6 or PAT-1 (Putative Anion Transporter 1), is regulated via cAMP when expressed in Xenopus oocytes and cultured cells but whether this translates to the native epithelia is unknown. This study investigated the regulation of oxalate transport by the mouse intestine focusing on transport at the apical membrane hypothesizing PAT-1 is the target of a cAMP-dependent signaling pathway. Adopting the Ussing chamber technique we measured unidirectional 14C-oxalate and 36Cl- flux ([Formula: see text] and [Formula: see text]) across distal ileum, cecum and distal colon, employing forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX) to trigger cAMP production. FSK/IBMX initiated a robust secretory response by all segments but the stimulation of net oxalate secretion was confined to the cecum only involving activation of [Formula: see text] and distinct from net Cl- secretion produced by inhibiting [Formula: see text]. Using the PAT-1 knockout (KO) mouse we determined cAMP-stimulated [Formula: see text] was not directly dependent on PAT-1, but it was sensitive to mucosal DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid), although unlikely to be another Cl-/HCO3- exchanger given the lack of trans-stimulation or cis-inhibition by luminal Cl- or HCO3-. The cAMP-activated oxalate efflux was reliant on CFTR (Cystic Fibrosis Transmembrane conductance Regulator) activity, but only in the presence of PAT-1, leading to speculation on the involvement of a multi-transporter regulatory complex. Further investigations at the cellular and molecular level are necessary to define the mechanism and transporter(s) responsible.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA.
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research | Internal Medicine, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-8885, USA.
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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9
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Jo S, Centeio R, Park J, Ousingsawat J, Jeon DK, Talbi K, Schreiber R, Ryu K, Kahlenberg K, Somoza V, Delpiano L, Gray MA, Amaral MD, Railean V, Beekman JM, Rodenburg LW, Namkung W, Kunzelmann K. The SLC26A9 inhibitor S9-A13 provides no evidence for a role of SLC26A9 in airway chloride secretion but suggests a contribution to regulation of ASL pH and gastric proton secretion. FASEB J 2022; 36:e22534. [PMID: 36183361 DOI: 10.1096/fj.202200313rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 08/11/2022] [Accepted: 08/24/2022] [Indexed: 11/11/2022]
Abstract
The solute carrier 26 family member A9 (SLC26A9) is an epithelial anion transporter that is assumed to contribute to airway chloride secretion and surface hydration. Whether SLC26A9 or CFTR is responsible for airway Cl- transport under basal conditions is still unclear, due to the lack of a specific inhibitor for SLC26A9. In the present study, we report a novel potent and specific inhibitor for SLC26A9, identified by screening of a drug-like molecule library and subsequent chemical modifications. The most potent compound S9-A13 inhibited SLC26A9 with an IC50 of 90.9 ± 13.4 nM. S9-A13 did not inhibit other members of the SLC26 family and had no effects on Cl- channels such as CFTR, TMEM16A, or VRAC. S9-A13 inhibited SLC26A9 Cl- currents in cells that lack expression of CFTR. It also inhibited proton secretion by HGT-1 human gastric cells. In contrast, S9-A13 had minimal effects on ion transport in human airway epithelia and mouse trachea, despite clear expression of SLC26A9 in the apical membrane of ciliated cells. In both tissues, basal and stimulated Cl- secretion was due to CFTR, while acidification of airway surface liquid by S9-A13 suggests a role of SLC26A9 for airway bicarbonate secretion.
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Affiliation(s)
- Sungwoo Jo
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Jinhong Park
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | | | - Dong-Kyu Jeon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Khaoula Talbi
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Kunhi Ryu
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Kristin Kahlenberg
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Veronika Somoza
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Livia Delpiano
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Michael A Gray
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Margarida D Amaral
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Lisbon, Portugal
| | - Violeta Railean
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Lisbon, Portugal
| | - Jeffrey M Beekman
- Regenerative Medicine Utrecht, University Medical Center, Utrecht University, Utrecht, Netherlands
| | - Lisa W Rodenburg
- Regenerative Medicine Utrecht, University Medical Center, Utrecht University, Utrecht, Netherlands
| | - Wan Namkung
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
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10
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Ferdaus MZ, Terker AS, Koumangoye R, Delpire E. KCC3a, a Strong Candidate Pathway for K+ Loss in Alkalemia. Front Cell Dev Biol 2022; 10:931326. [PMID: 35874803 PMCID: PMC9301082 DOI: 10.3389/fcell.2022.931326] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 05/24/2022] [Indexed: 11/13/2022] Open
Abstract
Loss-of-function mutations in the human potassium chloride cotransporter-3 (KCC3) cause a hereditary motor sensory neuropathy associated with agenesis of the corpus callosum. While recapitulating the neuropathy, KCC3-knockout mice also exhibit high blood pressure. This phenotype is believed to have neurogenic and/or vascular origins. The role of KCC3 in the kidney is poorly understood. KCC3 is encoded by two major isoforms originating from alternative promoters: KCC3a and KCC3b, with KCC3b being the predominant transcript in the kidney. Although the transporter has previously been localized to the proximal tubule, we show here the unique expression of the KCC3a isoform in the connecting tubule. Using a KCC3a-specific polyclonal antibody validated for both immunofluorescence and immunoblotting, we showed an intense KCC3a signal restricted to cortical intercalated cells. No overlap is detected between KCC3a and sodium chloride cotransporter (NCC), a distal convoluted tubule (DCT) marker; or between KCC3a and ENaC or calbindin, which are both principal cell markers. KCC3a signal was observed in cells expressing the apical V-ATPase and pendrin, establishing a unique expression pattern characteristic of intercalated cells of type-B or type-nonA/nonB. We further show that treatment of wild-type mice with hydrochlorothiazide, amiloride, or fed a K+-deficient diet up-regulates KCC3a level, suggesting that volume depletion increases KCC3a abundance. This hypothesis was confirmed by showing a higher abundance of KCC3a protein after 23-h water restriction or after placing the mice on a low-salt diet. More importantly, abundance of the Cl−/HCO3− exchanger, pendrin, which is known to secrete bicarbonate in alkalotic conditions, was significantly diminished in KCC3-knockout mice. In addition, KCC3a abundance increased significantly alongside pendrin abundance in bicarbonate-treated alkalotic mice, providing a credible mechanism for K+ loss in metabolic alkalosis.
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Affiliation(s)
- Mohammed Zubaerul Ferdaus
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Andrew Scott Terker
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Rainelli Koumangoye
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN, United States
- *Correspondence: Eric Delpire,
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11
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A Mathematical Model of Salivary Gland Duct Cells. Bull Math Biol 2022; 84:84. [PMID: 35799078 PMCID: PMC9262821 DOI: 10.1007/s11538-022-01041-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 06/14/2022] [Indexed: 11/18/2022]
Abstract
Saliva is produced in two stages in the salivary glands: the secretion of primary saliva by the acinus and the modification of saliva composition to final saliva by the intercalated and striated ducts. In order to understand the saliva modification process, we develop a mathematical model for the salivary gland duct. The model utilises the realistic 3D structure of the duct reconstructed from an image stack of gland tissue. Immunostaining results show that TMEM16A and aquaporin are expressed in the intercalated duct cells and that ENaC is not. Based on this, the model predicts that the intercalated duct does not absorb Na\documentclass[12pt]{minimal}
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\begin{document}$$^-$$\end{document}- like the striated duct but secretes a small amount of water instead. The input to the duct model is the time-dependent primary saliva generated by an acinar cell model. Our duct model produces final saliva output that agrees with the experimental measurements at various stimulation levels. It also shows realistic biological features such as duct cell volume, cellular concentrations and membrane potentials. Simplification of the model by omission of all detailed 3D structures of the duct makes a negligible difference to the final saliva output. This shows that saliva production is not sensitive to structural variation of the duct.
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12
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Choi I, Yang H, Kim E, Lee S. Bicarbonate-Independent Sodium Conductance of Na/HCO3 Cotransporter NBCn1 Decreases NMDA Receptor Function. Curr Issues Mol Biol 2022; 44:1284-1293. [PMID: 35723309 PMCID: PMC8947554 DOI: 10.3390/cimb44030086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 12/18/2022] Open
Abstract
The sodium bicarbonate cotransporter NBCn1 is an electroneutral transporter with a channel activity that conducts Na+ in a HCO3–-independent manner. This channel activity was suggested to functionally affect other membrane proteins which permeate Na+ influx. We previously reported that NBCn1 is associated with the NMDA receptors (NMDARs) at the molecular and physiological levels. In this study, we examined whether NBCn1 channel activity affects NMDAR currents and whether this effect involves the interaction between the two proteins. NBCn1 and the NMDAR subunits GluN1A/GluN2A were expressed in Xenopus oocytes, and glutamate currents produced by the receptors were measured using two-electrode voltage clamp. In the absence of CO2/HCO3–, NBCn1 channel activity decreased glutamate currents mediated by GluN1A/GluN2A. NBCn1 also decreased the slope of the current–voltage relationships for the glutamate current. Similar effects on the glutamate current were observed with and without PSD95, which can cluster NBCn1 and NMDARs. The channel activity was also observed in the presence of CO2/HCO3–. We conclude that NBCn1 channel activity decreases NMDAR function. Given that NBCn1 knockout mice develop a downregulation of NMDARs, our results are unexpected and suggest that NBCn1 has dual effects on NMDARs. It stabilizes NMDAR expression but decreases receptor function by its Na+ channel activity. The dual effects may play an important role in fine-tuning the regulation of NMDARs in the brain.
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13
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Ousingsawat J, Centeio R, Schreiber R, Kunzelmann K. Expression of SLC26A9 in Airways and Its Potential Role in Asthma. Int J Mol Sci 2022; 23:ijms23062998. [PMID: 35328418 PMCID: PMC8950296 DOI: 10.3390/ijms23062998] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/05/2022] [Accepted: 03/07/2022] [Indexed: 02/05/2023] Open
Abstract
SLC26A9 is an epithelial anion transporter with a poorly defined function in airways. It is assumed to contribute to airway chloride secretion and airway surface hydration. However, immunohistochemistry showing precise localization of SLC26A9 in airways is missing. Some studies report localization near tight junctions, which is difficult to reconcile with a chloride secretory function of SLC26A9. We therefore performed immunocytochemistry of SLC26A9 in sections of human and porcine lungs. Obvious apical localization of SLC26A9 was detected in human and porcine superficial airway epithelia, whereas submucosal glands did not express SLC26A9. The anion transporter was located exclusively in ciliated epithelial cells. Highly differentiated BCi-NS1 human airway epithelial cells grown on permeable supports also expressed SLC26A9 in the apical membrane of ciliated epithelial cells. BCi-NS1 cells expressed the major Cl− transporting proteins CFTR, TMEM16A and SLC26A9 in about equal proportions and produced short-circuit currents activated by increases in intracellular cAMP or Ca2+. Both CFTR and SLC26A9 contribute to basal chloride currents in non-stimulated BCi-NS1 airway epithelia, with CFTR being the dominating Cl− conductance. In wtCFTR-expressing CFBE human airway epithelial cells, SLC26A9 was partially located in the plasma membrane, whereas CFBE cells expressing F508del-CFTR showed exclusive cytosolic localization of SLC26A9. Membrane localization of SLC26A9 and basal chloride currents were augmented by interleukin 13 in wild-type CFTR-expressing cells, but not in cells expressing the most common disease-causing mutant F508del-CFTR. The data suggest an upregulation of SLC26A9-dependent chloride secretion in asthma, but not in the presence of F508del-CFTR.
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Affiliation(s)
| | | | | | - Karl Kunzelmann
- Correspondence: ; Tel.: +49-(0)941-943-4302; Fax: +49-(0)941-943-4315
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14
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Chloride Channels and Transporters: Roles beyond Classical Cellular Homeostatic pH or Ion Balance in Cancers. Cancers (Basel) 2022; 14:cancers14040856. [PMID: 35205604 PMCID: PMC8870652 DOI: 10.3390/cancers14040856] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/28/2022] [Accepted: 02/06/2022] [Indexed: 01/04/2023] Open
Abstract
Simple Summary Roles of chloride-associated transporters have been raised in various cancers. Although complicated ion movements, crosstalk among channels/transporters through homeostatic electric regulation, difficulties with experimental implementation such as activity measurement of intracellular location were disturbed to verify the precise modulation of channels/transporters, recently defined cancerous function and communication with tumor microenvironment of chloride channels/transporters should be highlighted beyond classical homeostatic ion balance. Chloride-associated transporters as membrane-associated components of chloride movement, regulations of transmembrane member 16A, calcium-activated chloride channel regulators, transmembrane member 206, chloride intracellular channels, voltage-gated chloride channels, cystic fibrosis transmembrane conductance regulator, voltage-dependent anion channel, volume-regulated anion channel, and chloride-bicarbonate exchangers are discussed. Abstract The canonical roles of chloride channels and chloride-associated transporters have been physiologically determined; these roles include the maintenance of membrane potential, pH balance, and volume regulation and subsequent cellular functions such as autophagy and cellular proliferative processes. However, chloride channels/transporters also play other roles, beyond these classical function, in cancerous tissues and under specific conditions. Here, we focused on the chloride channel-associated cancers and present recent advances in understanding the environments of various types of cancer caused by the participation of many chloride channel or transporters families and discuss the challenges and potential targets for cancer treatment. The modulation of chloride channels/transporters might promote new aspect of cancer treatment strategies.
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15
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Whittamore JM, Hatch M. Oxalate Flux Across the Intestine: Contributions from Membrane Transporters. Compr Physiol 2021; 12:2835-2875. [PMID: 34964122 DOI: 10.1002/cphy.c210013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epithelial oxalate transport is fundamental to the role occupied by the gastrointestinal (GI) tract in oxalate homeostasis. The absorption of dietary oxalate, together with its secretion into the intestine, and degradation by the gut microbiota, can all influence the excretion of this nonfunctional terminal metabolite in the urine. Knowledge of the transport mechanisms is relevant to understanding the pathophysiology of hyperoxaluria, a risk factor in kidney stone formation, for which the intestine also offers a potential means of treatment. The following discussion presents an expansive review of intestinal oxalate transport. We begin with an overview of the fate of oxalate, focusing on the sources, rates, and locations of absorption and secretion along the GI tract. We then consider the mechanisms and pathways of transport across the epithelial barrier, discussing the transcellular, and paracellular components. There is an emphasis on the membrane-bound anion transporters, in particular, those belonging to the large multifunctional Slc26 gene family, many of which are expressed throughout the GI tract, and we summarize what is currently known about their participation in oxalate transport. In the final section, we examine the physiological stimuli proposed to be involved in regulating some of these pathways, encompassing intestinal adaptations in response to chronic kidney disease, metabolic acid-base disorders, obesity, and following gastric bypass surgery. There is also an update on research into the probiotic, Oxalobacter formigenes, and the basis of its unique interaction with the gut epithelium. © 2021 American Physiological Society. Compr Physiol 11:1-41, 2021.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
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16
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Infield DT, Strickland KM, Gaggar A, McCarty NA. The molecular evolution of function in the CFTR chloride channel. J Gen Physiol 2021; 153:212705. [PMID: 34647973 PMCID: PMC8640958 DOI: 10.1085/jgp.202012625] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/11/2021] [Accepted: 09/09/2021] [Indexed: 12/13/2022] Open
Abstract
The ATP-binding cassette (ABC) transporter superfamily includes many proteins of clinical relevance, with genes expressed in all domains of life. Although most members use the energy of ATP binding and hydrolysis to accomplish the active import or export of various substrates across membranes, the cystic fibrosis transmembrane conductance regulator (CFTR) is the only known animal ABC transporter that functions primarily as an ion channel. Defects in CFTR, which is closely related to ABCC subfamily members that bear function as bona fide transporters, underlie the lethal genetic disease cystic fibrosis. This article seeks to integrate structural, functional, and genomic data to begin to answer the critical question of how the function of CFTR evolved to exhibit regulated channel activity. We highlight several examples wherein preexisting features in ABCC transporters were functionally leveraged as is, or altered by molecular evolution, to ultimately support channel function. This includes features that may underlie (1) construction of an anionic channel pore from an anionic substrate transport pathway, (2) establishment and tuning of phosphoregulation, and (3) optimization of channel function by specialized ligand–channel interactions. We also discuss how divergence and conservation may help elucidate the pharmacology of important CFTR modulators.
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Affiliation(s)
- Daniel T Infield
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | | | - Amit Gaggar
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL.,Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL.,Program in Protease and Matrix Biology, University of Alabama at Birmingham, Birmingham, AL.,Birmingham Veterans Administration Medical Center, Birmingham, AL
| | - Nael A McCarty
- Department of Pediatrics, Emory University, Atlanta, GA.,Children's Healthcare of Atlanta Center for Cystic Fibrosis and Airways Disease Research, Emory University, Atlanta, GA
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17
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Yu Q. Slc26a3 (DRA) in the Gut: Expression, Function, Regulation, Role in Infectious Diarrhea and Inflammatory Bowel Disease. Inflamm Bowel Dis 2021; 27:575-584. [PMID: 32989468 DOI: 10.1093/ibd/izaa256] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND The transport of transepithelial Cl- and HCO3- is crucial for the function of the intestinal epithelium and maintains the acid-based homeostasis. Slc26a3 (DRA), as a key chloride-bicarbonate exchanger protein in the intestinal epithelial luminal membrane, participates in the electroneutral NaCl absorption of intestine, together with Na+/H+ exchangers. Increasing recent evidence supports the essential role of decreased DRA function or expression in infectious diarrhea and inflammatory bowel disease (IBD). METHOD In this review, we give an overview of the current knowledge of Slc26a3, including its cloning and expression, function, roles in infectious diarrhea and IBD, and mechanisms of actions. A better understanding of the physiological and pathophysiological relevance of Slc26a3 in infectious diarrhea and IBD may reveal novel targets for future therapy. CONCLUSION Understanding the physiological function, regulatory interactions, and the potential mechanisms of Slc26a3 in the pathophysiology of infectious diarrhea and IBD will define novel therapeutic approaches in future.
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Affiliation(s)
- Qin Yu
- Department of Gastroenterology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan City, China
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18
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Abstract
PURPOSE OF REVIEW The gut-kidney axis plays a critical role in oxalate homeostasis, and better understanding of oxalate transport regulatory mechanisms is essential for developing novel therapies. RECENT FINDINGS Oxalate potentially contributes to chronic kidney disease (CKD) progression, CKD - and end stage renal disease (ESRD)-associated cardiovascular diseases, polycystic kidney disease (PKD) progression, and/or poor renal allograft survival, emphasizing the need for plasma and urinary oxalate lowering therapies. One promising strategy would be to enhance the bowel's ability to secrete oxalate, which might be facilitated by the following findings. Oxalobacter formigenes (O. formigenes)-derived factors recapitulate O. formigenes colonization effects by reducing urinary oxalate excretion in hyperoxaluric mice by inducing colonic oxalate secretion. Protein kinase A activation stimulates intestinal oxalate transport by enhancing the surface expression of the oxalate transporter SLC26A6 (A6). Glycosylation also stimulates A6-mediated oxalate transport. The colon adapts to chronic acidosis in rats through increased colonic oxalate secretion as previously reported in CKD rats, and A6-mediated enteric oxalate secretion is critical in reducing the body oxalate burden in CKD mice. Intestinal oxalate transport is negatively regulated by proinflammatory cytokines and cholinergic, purinergic, and adenosinergic signaling. SUMMARY These findings could facilitate the development of novel therapeutics for hyperoxalemia, hyperoxaluria, and related disorders if similar regulatory mechanisms are confirmed in humans.
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Affiliation(s)
- Altayeb E Alshaikh
- University of Chicago Pritzker School of Medicine
- University of Chicago, Chicago, Illinois, USA
| | - Hatim A Hassan
- University of Chicago Pritzker School of Medicine
- University of Chicago, Chicago, Illinois, USA
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19
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Hayashi H, Nagai H, Ohba KI, Soleimani M, Suzuki Y. Segmental differences in Slc26a3-dependent Cl - absorption and HCO 3- secretion in the mouse large intestine in vitro in Ussing chambers. J Physiol Sci 2021; 71:5. [PMID: 33514305 PMCID: PMC10717946 DOI: 10.1186/s12576-020-00784-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022]
Abstract
The anion exchanger slc26a3 (DRA), which is mutated in congenital chloride-losing diarrhea, is expressed in the apical membrane of the cecum and middle-distal colon but not in the proximal colon of rodent large intestines. To elucidate the functional roles of DRA, we measured unidirectional 36Cl- and 22Na+ fluxes and HCO3- secretion in vitro in each of these segments using DRA-KO mice. Robust Cl- absorption, which was largely abolished after DRA deficiency, was present in the cecum and middle-distal colon but absent in the proximal colon. Na+ absorption was present in all three segments in both the control and DRA-KO mice. The luminal-Cl--dependent HCO3- secretions in the cecum and middle-distal colon were abolished in the DRA-KO mice. In conclusion, DRA mediates Cl- absorption and HCO3- secretion in the mouse cecum and middle-distal colon, and may have roles in H2O absorption and luminal acid/base regulation in these segments.
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Affiliation(s)
- Hisayoshi Hayashi
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Hiroki Nagai
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Kou-Ichiro Ohba
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Yuichi Suzuki
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
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20
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Wang J, Wang W, Wang H, Tuo B. Physiological and Pathological Functions of SLC26A6. Front Med (Lausanne) 2021; 7:618256. [PMID: 33553213 PMCID: PMC7859274 DOI: 10.3389/fmed.2020.618256] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
Solute Carrier Family 26 (SLC26) is a conserved anion transporter family with 10 members in human (SLC26A1-A11, A10 being a pseudogene). All SLC26 genes except for SLC26A5 (prestin) are versatile anion exchangers with notable ability to transport a variety of anions. SLC26A6 has the most extensive exchange functions in the SLC26 family and is widely expressed in various organs and tissues of mammals. SLC26A6 has some special properties that make it play a particularly important role in ion homeostasis and acid-base balance. In the past few years, the function of SLC26A6 in the diseases has received increasing attention. SLC26A6 not only participates in the development of intestinal and pancreatic diseases but also serves a significant role in mediating nephrolithiasis, fetal skeletal dysplasia and arrhythmia. This review aims to explore the role of SLC26A6 in physiology and pathophysiology of relative mammalian organs to guide in-depth studies about related diseases of human.
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Affiliation(s)
- Juan Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Wenkang Wang
- Department of Critical Care Medicine of the Third Affiliated Hospital (The First People's Hospital of Zunyi City), Zunyi Medical University, Zunyi, China
| | - Hui Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
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21
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The anion exchanger PAT-1 (Slc26a6) does not participate in oxalate or chloride transport by mouse large intestine. Pflugers Arch 2020; 473:95-106. [PMID: 33205229 DOI: 10.1007/s00424-020-02495-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/23/2020] [Accepted: 11/10/2020] [Indexed: 01/20/2023]
Abstract
The membrane-bound transport proteins responsible for oxalate secretion across the large intestine remain unidentified. The apical chloride/bicarbonate (Cl-/HCO3-) exchanger encoded by Slc26a6, known as PAT-1 (putative anion transporter 1), is a potential candidate. In the small intestine, PAT-1 makes a major contribution to oxalate secretion but whether this role extends into the large intestine has not been directly tested. Using the PAT-1 knockout (KO) mouse, we compared the unidirectional absorptive ([Formula: see text]) and secretory ([Formula: see text]) flux of oxalate and Cl- across cecum, proximal colon, and distal colon from wild-type (WT) and KO mice in vitro. We also utilized the non-specific inhibitor DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid) to confirm a role for PAT-1 in WT large intestine and (in KO tissues) highlight any other apical anion exchangers involved. Under symmetrical, short-circuit conditions the cecum and proximal colon did not transport oxalate on a net basis, whereas the distal colon supported net secretion. We found no evidence for the participation of PAT-1, or indeed any other DIDS-sensitive transport mechanism, in oxalate or Cl- by the large intestine. Most unexpectedly, mucosal DIDS concurrently stimulated [Formula: see text] and [Formula: see text] by 25-68% across each segment without impacting net transport. For the colon, these changes were directly proportional to increased transepithelial conductance suggesting this response was the result of bidirectional paracellular flux. In conclusion, PAT-1 does not contribute to oxalate or Cl- transport by the large intestine, and we urge caution when using DIDS with mouse colonic epithelium.
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22
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Abstract
Although students initially learn of ionic buffering in basic chemistry, buffering and acid-base transport in biology often is relegated to specialized classes, discussions, or situations. That said, for physiology, nephrology, pulmonology, and anesthesiology, these basic principles often are critically important for mechanistic understanding, medical treatments, and assessing therapy effectiveness. This short introductory perspective focuses on basic chemistry and transport of buffers and acid-base equivalents, provides an outline of basic science acid-base concepts, tools used to monitor intracellular pH, model cellular responses to pH buffer changes, and the more recent development and use of genetically encoded pH-indicators. Examples of newer genetically encoded pH-indicators (pHerry and pHire) are provided, and their use for in vitro, ex vivo, and in vivo experiments are described. The continued use and development of these basic tools provide increasing opportunities for both basic and potentially clinical investigations.
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Affiliation(s)
- Michael F Romero
- Physiology and Biomedical Engineering, Nephrology and Hypertension, Mayo Clinic College of Medicine and Science, Rochester, MN.
| | - Adam J Rossano
- Physiology and Biomedical Engineering, Nephrology and Hypertension, Mayo Clinic College of Medicine and Science, Rochester, MN
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23
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Ullah AKMS, Rumley AC, Peleh V, Fernandes D, Almomani EY, Berrini M, Lashhab R, Touret N, Alexander RT, Herrmann JM, Cordat E. SLC26A7 protein is a chloride/bicarbonate exchanger and its abundance is osmolarity- and pH-dependent in renal epithelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183238. [PMID: 32119864 DOI: 10.1016/j.bbamem.2020.183238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/19/2020] [Accepted: 02/24/2020] [Indexed: 12/23/2022]
Abstract
Acid-secreting intercalated cells of the collecting duct express the chloride/bicarbonate kidney anion exchanger 1 (kAE1) as well as SLC26A7, two proteins that colocalize in the basolateral membrane. The latter protein has been reported to function either as a chloride/bicarbonate exchanger or a chloride channel. Both kAE1 and SLC26A7 are detected in the renal medulla, an environment hyper-osmotic to plasma. Individuals with mutations in the SLC4A1 gene encoding kAE1 and mice lacking Slc26a7 develop distal renal tubular acidosis (dRTA). Here, we aimed to (i) confirm that SLC26A7 can function as chloride/bicarbonate exchanger in Madin-Darby canine kidney (MDCK) cells, and (ii) examine the behavior of SLC26A7 relative to kAE1 wild type or carrying the dRTA mutation R901X in iso- or hyper-osmotic conditions mimicking the renal medulla. Although we found that SLC26A7 abundance increases in hyper-osmotic growth medium, it is reduced in low pH growth conditions mimicking acidosis when expressed at high levels in MDCK cells. In these cells, SLC26A7 exchange activity was independent from extracellular osmolarity. When SLC26A7 protein was co-expressed with kAE1 WT or the R901X dRTA mutant, the cellular chloride/bicarbonate exchange rate was not additive compared to when proteins are expressed individually, possibly reflecting a decreased overall protein expression. Furthermore, the cellular chloride/bicarbonate exchange rate was osmolarity-independent. Together, these results show that (i) in MDCK cells, SLC26A7 is a chloride/bicarbonate exchanger whose abundance is up-regulated by high osmolarity growth medium and (ii) acidic extracellular pH decreases the abundance of SLC26A7 protein.
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Affiliation(s)
| | - A Carly Rumley
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Valentina Peleh
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Daphne Fernandes
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Ensaf Y Almomani
- Faculty of Pharmacy, Al-Zaytoonah University of Jordan, Amman, Jordan
| | - Mattia Berrini
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Rawad Lashhab
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Nicolas Touret
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | | | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, AB, Canada.
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24
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Kim D, Huang J, Billet A, Abu-Arish A, Goepp J, Matthes E, Tewfik MA, Frenkiel S, Hanrahan JW. Pendrin Mediates Bicarbonate Secretion and Enhances Cystic Fibrosis Transmembrane Conductance Regulator Function in Airway Surface Epithelia. Am J Respir Cell Mol Biol 2020; 60:705-716. [PMID: 30742493 DOI: 10.1165/rcmb.2018-0158oc] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Bicarbonate facilitates mucin unpacking and bacterial killing; however, its transport mechanisms in the airways are not well understood. cAMP stimulates anion efflux through the cystic fibrosis (CF) transmembrane conductance regulator (CFTR; ABCC7) anion channel, and this is defective in CF. The anion exchanger pendrin (SLC26A4) also mediates HCO3- efflux and is upregulated by proinflammatory cytokines. Here, we examined pendrin and CFTR expression and their contributions to HCO3- secretion by human nasal and bronchial epithelia. In native tissue, both proteins were most abundant at the apical pole of ciliated surface cells with little expression in submucosal glands. In well-differentiated primary nasal and bronchial cell cultures, IL-4 dramatically increased pendrin mRNA levels and apical immunostaining. Exposure to low-Cl- apical solution caused intracellular alkalinization (ΔpHi) that was enhanced fourfold by IL-4 pretreatment. ΔpHi was unaffected by 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) or CFTR inhibitor CFTRinh-172, but was reduced by adenoviral shRNA targeting pendrin. Forskolin increased ΔpHi, and this stimulation was prevented by CFTRinh-172, implicating CFTR, yet forskolin only increased ΔpHi after pendrin expression had been induced by IL-4. The dependence of ΔpHi on pendrin suggests there is minimal electrical coupling between Cl- and HCO3- fluxes and that CFTR activation increases anion exchange-mediated HCO3- influx. Conversely, inducing pendrin expression increased forskolin-stimulated, CFTRinh-172-sensitive current by approximately twofold in epithelial and nonepithelial cells. We conclude that pendrin mediates most HCO3- secretion across airway surface epithelium during inflammation and enhances electrogenic Cl- secretion via CFTR, as described for other SLC26A transporters.
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Affiliation(s)
- Dusik Kim
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Junwei Huang
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Arnaud Billet
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Asmahan Abu-Arish
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Julie Goepp
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Elizabeth Matthes
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and
| | - Marc A Tewfik
- 2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and.,3 Department of Otolaryngology-Head and Neck Surgery and
| | - Saul Frenkiel
- 2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and.,3 Department of Otolaryngology-Head and Neck Surgery and
| | - John W Hanrahan
- 1 Department of Physiology and.,2 Cystic Fibrosis Translational Research Centre, McGill University, Montréal, Québec, Canada; and.,4 Research Institute, McGill University Health Centre, Montréal, Québec, Canada
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25
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Mouse pancreatic ductal organoid culture as a relevant model to study exocrine pancreatic ion secretion. J Transl Med 2020; 100:84-97. [PMID: 31409889 DOI: 10.1038/s41374-019-0300-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 06/19/2019] [Accepted: 06/19/2019] [Indexed: 12/14/2022] Open
Abstract
Pancreatic exocrine secretory processes are challenging to investigate on primary epithelial cells. Pancreatic organoid cultures may help to overcome shortcomings of the current models, however the ion secretory processes in pancreatic organoids-and therefore their physiological relevance or their utility in disease modeling-are not known. To answer these questions, we provide side-by-side comparison of gene expression, morphology, and function of epithelial cells in primary isolated pancreatic ducts and organoids. We used mouse pancreatic ductal fragments for experiments or were grown in Matrigel to obtain organoid cultures. Using PCR analysis we showed that gene expression of ion channels and transporters remarkably overlap in primary ductal cells and organoids. Morphological analysis with scanning electron microscopy revealed that pancreatic organoids form polarized monolayers with brush border on the apical membrane. Whereas the expression and localization of key proteins involved in ductal secretion (cystic fibrosis transmembrane conductance regulator, Na+/H+ exchanger 1 and electrogenic Na+/HCO3- cotransporter 1) are equivalent to the primary ductal fragments. Measurements of intracellular pH and Cl- levels revealed no significant difference in the activities of the apical Cl-/HCO3- exchange, or in the basolateral Na+ dependent HCO3- uptake. In summary we found that ion transport activities in the mouse pancreatic organoids are remarkably similar to those observed in freshly isolated primary ductal fragments. These results suggest that organoids can be suitable and robust model to study pancreatic ductal epithelial ion transport in health and diseases and facilitate drug development for secretory pancreatic disorders like cystic fibrosis, or chronic pancreatitis.
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Racz R, Nagy A, Rakonczay Z, Dunavari EK, Gerber G, Varga G. Defense Mechanisms Against Acid Exposure by Dental Enamel Formation, Saliva and Pancreatic Juice Production. Curr Pharm Des 2019; 24:2012-2022. [PMID: 29769002 PMCID: PMC6225347 DOI: 10.2174/1381612824666180515125654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 04/30/2018] [Accepted: 05/08/2018] [Indexed: 12/16/2022]
Abstract
The pancreas, the salivary glands and the dental enamel producing ameloblasts have marked developmental, structural and functional similarities. One of the most striking similarities is their bicarbonate-rich secretory product, serving acid neutralization. An important difference between them is that while pancreatic juice and saliva are delivered into a lumen where they can be collected and analyzed, ameloblasts produce locally precipitating hydroxyapatite which cannot be easily studied. Interestingly, the ion and protein secretion by the pancreas, the salivary glands, and maturation ameloblasts are all two-step processes, of course with significant differences too. As they all have to defend against acid exposure by producing extremely large quantities of bicarbonate, the failure of this function leads to deteriorating consequences. The aim of the present review is to describe and characterize the defense mechanisms of the pancreas, the salivary glands and enamel-producing ameloblasts against acid exposure and to compare their functional capabilities to do this by producing bicarbonate.
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Affiliation(s)
- Robert Racz
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Akos Nagy
- Department of Dentistry, Oral and Maxillofacial Surgery, University of Pecs, Pecs, Hungary
| | - Zoltan Rakonczay
- Department of Pathophysiology, University of Szeged, Szeged, Hungary
| | - Erika Katalin Dunavari
- Department of Dentistry, Oral and Maxillofacial Surgery, University of Pecs, Pecs, Hungary
| | - Gabor Gerber
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Gabor Varga
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
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Bernardino RL, Carrageta DF, Sousa M, Alves MG, Oliveira PF. pH and male fertility: making sense on pH homeodynamics throughout the male reproductive tract. Cell Mol Life Sci 2019; 76:3783-3800. [PMID: 31165202 PMCID: PMC11105638 DOI: 10.1007/s00018-019-03170-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 04/24/2019] [Accepted: 05/29/2019] [Indexed: 02/07/2023]
Abstract
In the male reproductive tract, ionic equilibrium is essential to maintain normal spermatozoa production and, hence, the reproductive potential. Among the several ions, HCO3- and H+ have a central role, mainly due to their role on pH homeostasis. In the male reproductive tract, the major players in pH regulation and homeodynamics are carbonic anhydrases (CAs), HCO3- membrane transporters (solute carrier 4-SLC4 and solute carrier 26-SLC26 family transporters), Na+-H+ exchangers (NHEs), monocarboxylate transporters (MCTs) and voltage-gated proton channels (Hv1). CAs and these membrane transporters are widely distributed throughout the male reproductive tract, where they play essential roles in the ionic balance of tubular fluids. CAs are the enzymes responsible for the production of HCO3- which is then transported by membrane transporters to ensure the maturation, storage, and capacitation of the spermatozoa. The transport of H+ is carried out by NHEs, Hv1, and MCTs and is essential for the electrochemical balance and for the maintenance of the pH within the physiological limits along the male reproductive tract. Alterations in HCO3- production and transport of ions have been associated with some male reproductive dysfunctions. Herein, we present an up-to-date review on the distribution and role of the main intervenient on pH homeodynamics in the fluids throughout the male reproductive tract. In addition, we discuss their relevance for the establishment of the male reproductive potential.
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Affiliation(s)
- Raquel L Bernardino
- Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar and Unit for Multidisciplinary Research in Biomedicine, University of Porto, Porto, Portugal
| | - David F Carrageta
- Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar and Unit for Multidisciplinary Research in Biomedicine, University of Porto, Porto, Portugal
| | - Mário Sousa
- Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar and Unit for Multidisciplinary Research in Biomedicine, University of Porto, Porto, Portugal
| | - Marco G Alves
- Institute of Biomedical Sciences Abel Salazar and Unit for Multidisciplinary Research in Biomedicine, University of Porto, Porto, Portugal
| | - Pedro F Oliveira
- Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar and Unit for Multidisciplinary Research in Biomedicine, University of Porto, Porto, Portugal.
- i3S-Institute for Innovation and Health Research, University of Porto, Porto, Portugal.
- Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.
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Kim Y, Jun I, Shin DH, Yoon JG, Piao H, Jung J, Park HW, Cheng MH, Bahar I, Whitcomb DC, Lee MG. Regulation of CFTR Bicarbonate Channel Activity by WNK1: Implications for Pancreatitis and CFTR-Related Disorders. Cell Mol Gastroenterol Hepatol 2019; 9:79-103. [PMID: 31561038 PMCID: PMC6889609 DOI: 10.1016/j.jcmgh.2019.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 12/28/2022]
Abstract
BACKGRAOUD & AIMS Aberrant epithelial bicarbonate (HCO3-) secretion caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is associated with several diseases including cystic fibrosis and pancreatitis. Dynamically regulated ion channel activity and anion selectivity of CFTR by kinases sensitive to intracellular chloride concentration ([Cl-]i) play an important role in epithelial HCO3- secretion. However, the molecular mechanisms of how [Cl-]i-dependent mechanisms regulate CFTR are unknown. METHODS We examined the mechanisms of the CFTR HCO3- channel regulation by [Cl-]i-sensitive kinases using an integrated electrophysiological, molecular, and computational approach including whole-cell, outside-out, and inside-out patch clamp recordings and molecular dissection of WNK1 and CFTR proteins. In addition, we analyzed the effects of pancreatitis-causing CFTR mutations on the WNK1-mediated regulation of CFTR. RESULTS Among the WNK1, SPAK, and OSR1 kinases that constitute a [Cl-]i-sensitive kinase cascade, the expression of WNK1 alone was sufficient to increase the CFTR bicarbonate permeability (PHCO3/PCl) and conductance (GHCO3) in patch clamp recordings. Molecular dissection of the WNK1 domains revealed that the WNK1 kinase domain is responsible for CFTR PHCO3/PCl regulation by direct association with CFTR, while the surrounding N-terminal regions mediate the [Cl-]i-sensitivity of WNK1. Furthermore, the pancreatitis-causing R74Q and R75Q mutations in the elbow helix 1 of CFTR hampered WNK1-CFTR physical associations and reduced WNK1-mediated CFTR PHCO3/PCl regulation. CONCLUSION The CFTR HCO3- channel activity is regulated by [Cl-]i and a WNK1-dependent mechanism. Our results provide new insights into the regulation of the ion selectivity of CFTR and the pathogenesis of CFTR-related disorders.
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Affiliation(s)
- Yonjung Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Ikhyun Jun
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea,Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | - Dong Hoon Shin
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Jihoon G. Yoon
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - He Piao
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Jinsei Jung
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea,Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
| | - Hyun Woo Park
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - Mary Hongying Cheng
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ivet Bahar
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - David C. Whitcomb
- Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Min Goo Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea,Correspondence Address correspondence to: Min Goo Lee, Department of Pharmacology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seoul 03722, Korea. fax: +82 2 313 1894.
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Rubenstein RC. Editorial Focus: CFTR-dependent bicarbonate secretion by Calu-3 cells. Physiol Rep 2019; 6:e13691. [PMID: 29845767 PMCID: PMC5974715 DOI: 10.14814/phy2.13691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Ronald C Rubenstein
- Division of Pulmonary Medicine and Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
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Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Kmit A, Marson FAL, Pereira SVN, Vinagre AM, Leite GS, Servidoni MF, Ribeiro JD, Ribeiro AF, Bertuzzo CS, Amaral MD. Extent of rescue of F508del-CFTR function by VX-809 and VX-770 in human nasal epithelial cells correlates with SNP rs7512462 in SLC26A9 gene in F508del/F508del Cystic Fibrosis patients. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1323-1331. [PMID: 30716472 DOI: 10.1016/j.bbadis.2019.01.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/16/2019] [Accepted: 01/30/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND We analyzed the CFTR response to VX-809/VX-770 drugs in conditionally reprogrammed cells (CRC) of human nasal epithelium (HNE) from F508del/F508del patients based on SNP rs7512462 in the Solute Carrier Family 26, Member 9 (SLC26A9; MIM: 608481) gene. METHODS The Isc-eq measurements of primary nasal epithelial cells from F508del/F508del patients (n = 12) for CFTR function were performed in micro Ussing chambers and compared with non-CF controls (n = 2). Data were analyzed according to the rs7512462 genotype which were determined by real-time PCR. RESULTS The CRC-HNE cells from F508del/F508del patients evidenced high variability in the basal levels of CFTR function. Also, the rs7512462*C allele showed an increased basal CFTR function and higher responses to VX-809 + VX-770. The rs7512462*CC + CT genotypes together evidenced CFTR function levels of 14.89% relatively to wt/wt (rs7512462*CT alone-15.29%) i.e., almost double of rs7512462*TT (7.13%). Furthermore, sweat [Cl-] and body mass index of patients also evidenced an association with the rs7512462 genotype. CONCLUSION The CFTR function can be performed in F508del/F508del patient-derived CRC-HNEs and its function and responses to VX-809 + VX-770 combination as well as clinical data, are all associated with the rs7512462 variant, which partially sheds light on the generally inter-individual phenotypic variability and in personalized responses to CFTR modulator drugs.
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Affiliation(s)
- Arthur Kmit
- Department of Medical Genetics and Genomic Medicine, Faculty of Medical Sciences, University of Campinas, Brazil; Department of Pediatrics, Faculty of Medical Sciences, University of Campinas, Brazil.
| | - Fernando Augusto Lima Marson
- Department of Medical Genetics and Genomic Medicine, Faculty of Medical Sciences, University of Campinas, Brazil; Department of Pediatrics, Faculty of Medical Sciences, University of Campinas, Brazil.
| | - Stéphanie Villa-Nova Pereira
- Department of Medical Genetics and Genomic Medicine, Faculty of Medical Sciences, University of Campinas, Brazil
| | | | - Gabriela Silva Leite
- Department of Pediatrics, Faculty of Medical Sciences, University of Campinas, Brazil
| | | | - José Dirceu Ribeiro
- Department of Pediatrics, Faculty of Medical Sciences, University of Campinas, Brazil
| | | | - Carmen Sílvia Bertuzzo
- Department of Medical Genetics and Genomic Medicine, Faculty of Medical Sciences, University of Campinas, Brazil.
| | - Margarida Duarte Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Portugal.
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cAMP Stimulates SLC26A3 Activity in Human Colon by a CFTR-Dependent Mechanism That Does Not Require CFTR Activity. Cell Mol Gastroenterol Hepatol 2019; 7:641-653. [PMID: 30659943 PMCID: PMC6438990 DOI: 10.1016/j.jcmgh.2019.01.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS SLC26A3 (DRA) is an electroneutral Cl-/HCO3- exchanger that is present in the apical domain of multiple intestinal segments. An area that has continued to be poorly understood is related to DRA regulation in acute adenosine 3',5'-cyclic monophosphate (cAMP)-related diarrheas, in which DRA appears to be both inhibited as part of NaCl absorption and stimulated to contribute to increased HCO3- secretion. Different cell models expressing DRA have shown that cAMP inhibits, stimulates, or does not affect its activity. METHODS This study re-evaluated cAMP regulation of DRA using new tools, including a successful knockout cell model, a specific DRA inhibitor (DRAinh-A250), specific antibodies, and a transport assay that did not rely on nonspecific inhibitors. The studies compared DRA regulation in colonoids made from normal human colon with regulation in the colon cancer cell line, Caco-2. RESULTS DRA is an apical protein in human proximal colon, differentiated colonoid monolayers, and Caco-2 cells. It is glycosylated and appears as 2 bands. cAMP (forskolin) acutely stimulated DRA activity in human colonoids and Caco-2 cells. In these cells, DRA is the predominant apical Cl-/HCO3- exchanger and is inhibited by DRAinh-A250 with a median inhibitory concentration of 0.5 and 0.2 μmol/L, respectively. However, there was no effect of cAMP in HEK293/DRA cells that lacked a cystic fibrosis transmembrane conductance regulator (CFTR). When CFTR was expressed in HEK293/DRA cells, cAMP also stimulated DRA activity. In all cases, cAMP stimulation of DRA was not inhibited by CFTRinh-172. CONCLUSIONS DRA is acutely stimulated by cAMP by a process that is CFTR-dependent, but appears to be one of multiple regulatory effects of CFTR that does not require CFTR activity.
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Vachel L, Muallem S. CFTR is not a gluten lover either. EMBO J 2019; 38:embj.2018101200. [PMID: 30573671 DOI: 10.15252/embj.2018101200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Laura Vachel
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Shmuel Muallem
- Epithelial Signaling and Transport Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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34
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Takei Y, Wong MKS, Ando M. Molecular mechanisms for intestinal HCO3− secretion and its regulation by guanylin in seawater-acclimated eels. J Exp Biol 2019; 222:jeb.203539. [DOI: 10.1242/jeb.203539] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/03/2019] [Indexed: 01/25/2023]
Abstract
The intestine of marine teleosts secretes HCO3− into the lumen and precipitates Ca2+ and Mg2+ in the imbibed seawater as carbonates to decrease luminal fluid osmolality and facilitate water absorption. However, hormonal regulation of HCO3−secretion is largely unknown. Here, mucosally-added guanylin (GN) increased HCO3− secretion, measured by pH-stat, across isolated seawater-acclimated eel intestine bathed in saline at pH 7.4 (5% CO2). The effect of GN on HCO3− secretion was slower than that on the short-circuit current, and the time-course of the GN effect was similar to that of bumetanide. Mucosal bumetanide and serosal 4,4’-dinitrostilbene-2,2’-disulfonic acid (DNDS) inhibited the GN effect, suggesting an involvement of apical Na+-K+-2Cl− cotransporter (NKCC2) and basolateral Cl−/HCO3− exchanger (AE)/Na+-HCO3− cotransporter (NBC) in the GN effect. As mucosal DNDS failed to inhibit the GN effect, apical DNDS-sensitive AE may not be involved. To identify molecular species of transporters involved in the GN effect, we performed RNA-seq analyses followed by quantitative real-time PCR after transfer of eels to seawater. Among the genes upregulated after seawater transfer, AE genes, draa, b, and pat1a, c, on the apical membrane, and NBC genes, nbce1a, n1, n2a, and a AE gene, sat-1, on the basolateral membrane were candidates involved in HCO3− secretion. Judging from the slow effect of GN, we suggest that GN inhibits NKCC2b on the apical membrane and decreases cytosolic Cl− and Na+, which then activates apical DNDS-insensitive DRAs and basolateral DNDS-sensitive NBCs to enhance transcellular HCO3− flux across the intestinal epithelia of seawater-acclimated eels.
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Affiliation(s)
- Yoshio Takei
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Marty K. S. Wong
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba 277-8564, Japan
| | - Masaaki Ando
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba 277-8564, Japan
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El Khouri E, Whitfield M, Stouvenel L, Kini A, Riederer B, Lores P, Roemermann D, di Stefano G, Drevet JR, Saez F, Seidler U, Touré A. Slc26a3 deficiency is associated with epididymis dysplasia and impaired sperm fertilization potential in the mouse. Mol Reprod Dev 2018; 85:682-695. [PMID: 30118583 DOI: 10.1002/mrd.23055] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/16/2018] [Indexed: 12/25/2022]
Abstract
Members of the solute carrier 26 (SLC26) family have emerged as important players in mediating anions fluxes across the plasma membrane of epithelial cells, in cooperation with the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Among them, SLC26A3 acts as a chloride/bicarbonate exchanger, highly expressed in the gastrointestinal, pancreatic and renal tissues. In humans, mutations in the SLC26A3 gene were shown to induce congenital chloride-losing diarrhea (CLD), a rare autosomal recessive disorder characterized by life-long secretory diarrhea. In view of some reports indicating subfertility in some male CLD patients together with SLC26-A3 and -A6 expression in the male genital tract and sperm cells, we analyzed the male reproductive parameters and functions of SLC26A3 deficient mice, which were previously reported to display CLD gastro-intestinal features. We show that in contrast to Slc26a6, deletion of Slc26a3 is associated with severe lesions and abnormal cytoarchitecture of the epididymis, together with sperm quantitative, morphological and functional defects, which altogether compromised male fertility. Overall, our work provides new insight into the pathophysiological mechanisms that may alter the reproductive functions and lead to male subfertility in CLD patients, with a phenotype reminiscent of that induced by CFTR deficiency in the male genital tract.
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Affiliation(s)
- Elma El Khouri
- INSERM, U1016, Institut Cochin, Departement of Development, Reproduction and Cancer, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | - Marjorie Whitfield
- INSERM, U1016, Institut Cochin, Departement of Development, Reproduction and Cancer, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France.,CNRS, UMR6293, INSERM U1103, GReD, Université Clermont Auvergne, Aubière, France
| | - Laurence Stouvenel
- INSERM, U1016, Institut Cochin, Departement of Development, Reproduction and Cancer, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | - Archana Kini
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Patrick Lores
- INSERM, U1016, Institut Cochin, Departement of Development, Reproduction and Cancer, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
| | | | | | - Joël R Drevet
- CNRS, UMR6293, INSERM U1103, GReD, Université Clermont Auvergne, Aubière, France
| | - Fabrice Saez
- CNRS, UMR6293, INSERM U1103, GReD, Université Clermont Auvergne, Aubière, France
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Aminata Touré
- INSERM, U1016, Institut Cochin, Departement of Development, Reproduction and Cancer, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Paris, France
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36
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Figueira MF, Webster MJ, Tarran R. CrossTalk proposal: mucosal acidification drives early progressive lung disease in cystic fibrosis. J Physiol 2018; 596:3433-3437. [PMID: 30014571 DOI: 10.1113/jp275425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/14/2018] [Indexed: 12/27/2022] Open
Affiliation(s)
- Miriam F Figueira
- Cystic Fibrosis Center/Marsico Lung Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Megan J Webster
- Cystic Fibrosis Center/Marsico Lung Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert Tarran
- Cystic Fibrosis Center/Marsico Lung Institute, University of North Carolina, Chapel Hill, NC 27599, USA.,Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
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Jiang H, Pokhrel G, Chen Y, Wang T, Yin C, Liu J, Wang S, Liu Z. High expression of SLC26A6 in the kidney may contribute to renal calcification via an SLC26A6-dependent mechanism. PeerJ 2018; 6:e5192. [PMID: 30002986 PMCID: PMC6034601 DOI: 10.7717/peerj.5192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 06/18/2018] [Indexed: 12/12/2022] Open
Abstract
Background Solute-linked carrier 26 gene family 6 (SLC26A6), which is mainly expressed in intestines and kidneys, is a multifunctional anion transporter crucial in the transport of oxalate anions. This study aimed to investigate the role of kidney SLC26A6 in urolithiasis. Methods Patients were divided into two groups: stone formers and nonstone formers. Samples were collected from patients following nephrectomy. Lentivirus with Slc26a6 (lentivirus-Slc26a6) sequence and lentivirus with siRNA-Slc26a6 (lentivirus-siRNA-Slc26a6) sequence were transfected into rats’ kidneys respectively and Slc26a6 expression was detected using Western blot and immunohistochemical analyses. After administering ethylene glycol, oxalate concentration and prevalence of stone formation between the transgenic and control groups were measured using 24-h urine analysis and Von Kossa staining, respectively. Results Immunohistochemical and Western blot analyses indicated that stone formers had a significantly higher level of expression of SLC26A6 in the kidney compared with the control group. After lentivirus infection, the urinary oxalate concentration and rate of stone formation in lentivirus-Slc26a6-tranfected rats increased remarkably, while lentivirus-siRNA-Slc26a6-transfected rats showed few crystals. Conclusion The results showed that high expression levels of renal SLC26A6 may account for kidney stone formation. Downregulating the expression of SLC26A6 in the kidney may be a potential therapeutic target to prevent or treat urolithiasis.
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Affiliation(s)
- Hongyang Jiang
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Gaurab Pokhrel
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yinwei Chen
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tao Wang
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chunping Yin
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jihong Liu
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shaogang Wang
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhuo Liu
- Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Massip-Copiz MM, Santa-Coloma TA. Extracellular pH and lung infections in cystic fibrosis. Eur J Cell Biol 2018; 97:402-410. [PMID: 29933921 DOI: 10.1016/j.ejcb.2018.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/01/2018] [Accepted: 06/12/2018] [Indexed: 12/11/2022] Open
Abstract
Cystic fibrosis (CF) is an autosomal recessive disease caused by CFTR mutations. It is characterized by high NaCl concentration in sweat and the production of a thick and sticky mucus, occluding secretory ducts, intestine and airways, accompanied by chronic inflammation and infections of the lungs. This causes a progressive and lethal decline in lung function. Therefore, finding the mechanisms driving the high susceptibility to lung infections has been a key issue. For decades the prevalent hypothesis was that a reduced airway surface liquid (ASL) volume and composition, and the consequent increased mucus concentration (dehydration), create an environment favoring infections. However, a few years ago, in a pig model of CF, the Na+/K+ concentrations and the ASL volume were found intact. Immediately a different hypothesis arose, postulating a reduced ASL pH as the cause for the increased susceptibility to infections, due to a diminished bicarbonate secretion through CFTR. Noteworthy, a recent report found normal ASL pH values in CF children and in cultured primary airway cells, challenging the ASL pH hypothesis. On the other hand, recent evidences revitalized the hypothesis of a reduced ASL secretion. Thus, the role of the ASL pH in the CF is still a controversial matter. In this review we discuss the basis that sustain the role of CFTR in modulating the extracellular pH, and the recent results sustaining the different points of view. Finding the mechanisms of CFTR signaling that determine the susceptibility to infections is crucial to understand the pathophysiology of CF and related lung diseases.
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Affiliation(s)
- María Macarena Massip-Copiz
- Laboratory of Cellular and Molecular Biology, Institute for Biomedical Research (BIOMED UCA-CONICET), The National Scientific and Technical Research Council (CONICET), and School of Medical Sciences, The Pontifical Catholic University of Argentina (UCA), Buenos Aires, Argentina
| | - Tomás Antonio Santa-Coloma
- Laboratory of Cellular and Molecular Biology, Institute for Biomedical Research (BIOMED UCA-CONICET), The National Scientific and Technical Research Council (CONICET), and School of Medical Sciences, The Pontifical Catholic University of Argentina (UCA), Buenos Aires, Argentina.
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Zhang J, Wang Y, Jiang X, Chan HC. Cystic fibrosis transmembrane conductance regulator-emerging regulator of cancer. Cell Mol Life Sci 2018; 75:1737-1756. [PMID: 29411041 PMCID: PMC11105598 DOI: 10.1007/s00018-018-2755-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/27/2017] [Accepted: 01/17/2018] [Indexed: 12/11/2022]
Abstract
Mutations of cystic fibrosis transmembrane conductance regulator (CFTR) cause cystic fibrosis, the most common life-limiting recessive genetic disease among Caucasians. CFTR mutations have also been linked to increased risk of various cancers but remained controversial for a long time. Recent studies have begun to reveal that CFTR is not merely an ion channel but also an important regulator of cancer development and progression with multiple signaling pathways identified. In this review, we will first present clinical findings showing the correlation of genetic mutations or aberrant expression of CFTR with cancer incidence in multiple cancers. We will then focus on the roles of CFTR in fundamental cellular processes including transformation, survival, proliferation, migration, invasion and epithelial-mesenchymal transition in cancer cells, highlighting the signaling pathways involved. Finally, the association of CFTR expression levels with patient prognosis, and the potential of CFTR as a cancer prognosis indicator in human malignancies will be discussed.
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Affiliation(s)
- Jieting Zhang
- Faculty of Medicine, Epithelial Cell Biology Research Center, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China
- Key Laboratory for Regenerative Medicine of the Ministry of Education of China, Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China
- School of Biomedical Sciences Core Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People's Republic of China
| | - Yan Wang
- Faculty of Medicine, Epithelial Cell Biology Research Center, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China
- Key Laboratory for Regenerative Medicine of the Ministry of Education of China, Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China
- School of Biomedical Sciences Core Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People's Republic of China
| | - Xiaohua Jiang
- Faculty of Medicine, Epithelial Cell Biology Research Center, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China.
- Key Laboratory for Regenerative Medicine of the Ministry of Education of China, Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China.
- School of Biomedical Sciences Core Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People's Republic of China.
| | - Hsiao Chang Chan
- Faculty of Medicine, Epithelial Cell Biology Research Center, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China.
- Key Laboratory for Regenerative Medicine of the Ministry of Education of China, Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Sha Tin, Hong Kong SAR, People's Republic of China.
- School of Biomedical Sciences Core Laboratory, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People's Republic of China.
- Sichuan University-The Chinese University of Hong Kong Joint Laboratory for Reproductive Medicine, West China Second University Hospital, Chengdu, People's Republic of China.
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40
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Hu MY, Yan JJ, Petersen I, Himmerkus N, Bleich M, Stumpp M. A SLC4 family bicarbonate transporter is critical for intracellular pH regulation and biomineralization in sea urchin embryos. eLife 2018; 7:36600. [PMID: 29714685 PMCID: PMC5986267 DOI: 10.7554/elife.36600] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 04/30/2018] [Indexed: 12/21/2022] Open
Abstract
Efficient pH regulation is a fundamental requisite of all calcifying systems in animals and plants but with the underlying pH regulatory mechanisms remaining largely unknown. Using the sea urchin larva, this work identified the SLC4 HCO3- transporter family member SpSlc4a10 to be critically involved in the formation of an elaborate calcitic endoskeleton. SpSlc4a10 is specifically expressed by calcifying primary mesenchyme cells with peak expression during de novo formation of the skeleton. Knock-down of SpSlc4a10 led to pH regulatory defects accompanied by decreased calcification rates and skeleton deformations. Reductions in seawater pH, resembling ocean acidification scenarios, led to an increase in SpSlc4a10 expression suggesting a compensatory mechanism in place to maintain calcification rates. We propose a first pH regulatory and HCO3- concentrating mechanism that is fundamentally linked to the biological precipitation of CaCO3. This knowledge will help understanding biomineralization strategies in animals and their interaction with a changing environment. Many marine organisms such as mussels, sea urchins or corals, have skeletons and shells, which – due to their beautiful colors and shapes – are often desirable collector pieces. These structures are made from calcium and carbonate ions that react to form calcium carbonate crystals in a process known as biomineralization. In sea urchin larvae, for example, the skeleton is built by so-called primary mesenchyme cells, which work similar to the bone forming cells in mammals. These mesenchyme cells use calcium from the sea water, which travels to the site where the shell starts to form. About half of the carbonate comes from carbon dioxide that the animals make as they breathe, but it is not known how the other half gets to the site of biomineralization. Producing a skeleton generates acid, and marine animals need to be able to regulate their pH levels, as too acidic environments can dissolve the calcium carbonate and threatening to destroy the developing shell. How cells accumulate enough carbonate to make their shells, and how they cope with acidity is still poorly understood. Here, Hu et al. address this problem by studying purple sea urchin larvae, revealing that they use ion transporters to gather bicarbonate from seawater. These structures are part of a group of bicarbonate transporters known as the ‘SLC4 transporter family’, which sit across the membrane of the mesenchyme cells and move the bicarbonate ions along. As the sea urchin larvae develop, the levels of the transporter protein start to rise in mesenchyme cells, peaking around the time they are producing the skeleton. Stopping the production of the transporter hindered the larvae from building normal skeletons and also made their cells more acidic. It turns out that bicarbonate is more than a skeleton ingredient – it also helps to buffer the acid made in the process. Bicarbonate ions can combine with acidic molecules to form water and carbon dioxide. Bicarbonate pumped in from the sea neutralises the acidic molecules made during calcium carbonate formation, which helps to stabilize pH levels. When the acidity of the water was experimentally increased, it prompted the sea urchins to produce more of the SLC4 transporters, revealing that they may have another role to play. Their acid-neutralizing capability helped the animals to cope with changes in their environment. Taking on more bicarbonate could therefore help to compensate for rising acidity, allowing skeleton production to carry on as normal. This last finding is important in the context of ocean acidification. As the amount of carbon dioxide in the atmosphere increases, more of the gas dissolves in the sea. The chemical reactions that follow make the water more acidic and decreases the pH levels of the sea. Understanding how animals make their skeletons and shells, and manage acid, could reveal how they will cope as the environment changes in the future.
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Affiliation(s)
- Marian Y Hu
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Jia-Jiun Yan
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany.,Institute of Cellular and Organismic Biology, Taipei, Taiwan
| | - Inga Petersen
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Markus Bleich
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Meike Stumpp
- Comparative Immunobiology, Institute of Zoology, Christian-Albrechts University of Kiel, Kiel, Germany
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Ruhr IM, Schauer KL, Takei Y, Grosell M. Renoguanylin stimulates apical CFTR translocation and decreases HCO 3- secretion through PKA activity in the Gulf toadfish ( Opsanus beta). ACTA ACUST UNITED AC 2018; 221:jeb.173948. [PMID: 29361605 DOI: 10.1242/jeb.173948] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/15/2018] [Indexed: 01/07/2023]
Abstract
The guanylin peptides - guanylin, uroguanylin and renoguanylin (RGN) - are endogenously produced hormones in teleost fish enterocytes that are activators of guanylyl cyclase-C (GC-C) and are potent modulators of intestinal physiology, particularly in seawater teleosts. Most notably, they reverse normal net ion-absorbing mechanisms that are vital to water absorption, an important process for seawater teleost survival. The role of guanylin-peptide stimulation of the intestine remains unclear, but it is hypothesized to facilitate the removal of solids from the intestine by providing fluid to enable their removal by peristalsis. The present study used one member of this group of peptides - RGN - to provide evidence for the prominent role that protein kinase A (PKA) plays in mediating the effects of guanylin-peptide stimulation in the posterior intestine of the Gulf toadfish (Opsanus beta). Protein kinase G was found to not mediate the intracellular effects of RGN, despite previous evidence showing that GC-C activation leads to higher cyclic guanosine monophosphate formation. RGN reversed the absorptive short-circuit current and increased conductance in the Gulf toadfish intestine. These effects are correlated to increased trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel to the apical membrane, which is negated by PKA inhibition. Moreover, RGN decreased HCO3- secretion, likely by limiting apical HCO3-/Cl- exchange (possibly by reducing SLC26a6 activity), a reduction that was enhanced by PKA inhibition. RGN seems to alter PKA activity in the posterior intestine to recruit CFTR to the apical membrane and reduce HCO3- secretion.
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Affiliation(s)
- Ilan M Ruhr
- Department of Marine Biology and Ecology, The Rosenstiel School of Marine and Atmospheric Science, The University of Miami, Miami, FL 33149, USA
| | - Kevin L Schauer
- Department of Marine Biology and Ecology, The Rosenstiel School of Marine and Atmospheric Science, The University of Miami, Miami, FL 33149, USA
| | - Yoshio Takei
- Department of Marine Bioscience, The Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Martin Grosell
- Department of Marine Biology and Ecology, The Rosenstiel School of Marine and Atmospheric Science, The University of Miami, Miami, FL 33149, USA
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42
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Andharia N, Hayashi M, Matsuda H. Electrophysiological properties of anion exchangers in the luminal membrane of guinea pig pancreatic duct cells. Pflugers Arch 2018; 470:897-907. [PMID: 29399744 PMCID: PMC5945753 DOI: 10.1007/s00424-018-2116-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/10/2018] [Accepted: 01/23/2018] [Indexed: 12/12/2022]
Abstract
The pancreatic duct epithelium secretes the HCO3−-rich pancreatic juice. The HCO3− transport across the luminal membrane has been proposed to be mediated by SLC26A Cl−–HCO3− exchangers. To examine the electrophysiological properties of Cl−–HCO3− exchangers, we directly measured HCO3− conductance in the luminal membrane of the interlobular pancreatic duct cells from guinea pigs using an inside-out patch-clamp technique. Intracellular HCO3− increased the HCO3− conductance with a half-maximal effective concentration value of approximately 30 mM. The selectivity sequence based on permeability ratios was SCN− (1.4) > Cl− (1.2) = gluconate (1.1) = I− (1.1) = HCO3− (1.0) > methanesulfonate (0.6). The sequence of the relative conductance was HCO3− (1.0) > SCN− (0.7) = I− (0.7) > Cl− (0.5) = gluconate (0.4) > methanesulfonate (0.2). The current dependent on intracellular HCO3− was reduced by replacement of extracellular Cl− with gluconate or by H2DIDS, an inhibitor of Cl−–HCO3− exchangers. RT-PCR analysis revealed that the interlobular and main ducts expressed all SLC26A family members except Slc26a5 and Slc26a8. SLC26A1, SLC26A4, SLC26A6, and SLC26A10 were found to be localized to the luminal membrane of the guinea pig pancreatic duct by immunohistochemistry. These results demonstrate that these SLC26A Cl−–HCO3− exchangers may mediate the electrogenic HCO3− transport through the luminal membrane and may be involved in pancreatic secretion in guinea pig ducts.
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Affiliation(s)
- N Andharia
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, 573-1010, Japan
| | - M Hayashi
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, 573-1010, Japan.
| | - H Matsuda
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, 573-1010, Japan
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Wedenoja S, Khamaysi A, Shimshilashvili L, Anbtawe-Jomaa S, Elomaa O, Toppari J, Höglund P, Aittomäki K, Holmberg C, Hovatta O, Tapanainen JS, Ohana E, Kere J. A missense mutation in SLC26A3 is associated with human male subfertility and impaired activation of CFTR. Sci Rep 2017; 7:14208. [PMID: 29079751 PMCID: PMC5660164 DOI: 10.1038/s41598-017-14606-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 10/09/2017] [Indexed: 12/21/2022] Open
Abstract
Chloride absorption and bicarbonate excretion through exchange by the solute carrier family 26 member 3 (SLC26A3) and cystic fibrosis transmembrane conductance regulator (CFTR) are crucial for many tissues including sperm and epithelia of the male reproductive tract. Homozygous SLC26A3 mutations cause congenital chloride diarrhea with male subfertility, while homozygous CFTR mutations cause cystic fibrosis with male infertility. Some homozygous or heterozygous CFTR mutations only manifest as male infertility. Accordingly, we studied the influence of SLC26A3 on idiopathic infertility by sequencing exons of SLC26A3 in 283 infertile and 211 control men. A heterozygous mutation c.2062 G > C (p.Asp688His) appeared in nine (3.2%) infertile men, and additionally, in two (0.9%) control men, whose samples revealed a sperm motility defect. The p.Asp688His mutation is localized in the CFTR-interacting STAS domain of SLC26A3 and enriched in Finland, showing a significant association with male infertility in comparison with 6,572 Finnish (P < 0.05) and over 120,000 global alleles (P < 0.0001) (ExAC database). Functional studies showed that while SLC26A3 is a strong activator of CFTR-dependent anion transport, SLC26A3-p.Asp688His mutant retains normal Cl−/HCO3− exchange activity but suppresses CFTR, despite unaffected domain binding and expression. These results suggest a novel mechanism for human male infertility─impaired anion transport by the coupled SLC26A3 and CFTR.
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Affiliation(s)
- Satu Wedenoja
- Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, FI-00014, Helsinki, Finland.
| | - Ahlam Khamaysi
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Liana Shimshilashvili
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Shireen Anbtawe-Jomaa
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Outi Elomaa
- Folkhälsan Institute of Genetics, and Molecular Neurology Research Program, University of Helsinki, FI-00014, Helsinki, Finland
| | - Jorma Toppari
- Department of Physiology, Institute of Biomedicine, University of Turku, and Department of Pediatrics, Turku University Hospital, FI-20014, Turku, Finland
| | - Pia Höglund
- City of Kauniainen, Health Care Services, FI-02700, Kauniainen, Finland
| | - Kristiina Aittomäki
- HUSLAB, Laboratory of Genetics, Helsinki University Hospital, and Genome-Scale Biology research program, University of Helsinki, FI-00029, Helsinki, Finland
| | - Christer Holmberg
- Hospital for Children and Adolescents, University of Helsinki and Helsinki University Hospital, FI-00014, Helsinki, Finland
| | - Outi Hovatta
- Department of Clinical Science, Karolinska Institutet, SE-17177, Stockholm, Sweden
| | - Juha S Tapanainen
- Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, FI-00014, Helsinki, Finland.,Obstetrics and Gynecology, University of Oulu and Oulu University Hospital, FI-90220, Oulu, Finland
| | - Ehud Ohana
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
| | - Juha Kere
- Folkhälsan Institute of Genetics, and Molecular Neurology Research Program, University of Helsinki, FI-00014, Helsinki, Finland.,Department of Biosciences and Nutrition, Karolinska Institutet, SE-14183, Huddinge, Sweden.,Department of Medical & Molecular Genetics, King's College London, London, SE1 9RT, England
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Rapp C, Bai X, Reithmeier RAF. Molecular analysis of human solute carrier SLC26 anion transporter disease-causing mutations using 3-dimensional homology modeling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2420-2434. [PMID: 28941661 DOI: 10.1016/j.bbamem.2017.09.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 06/08/2017] [Accepted: 09/14/2017] [Indexed: 12/22/2022]
Abstract
The availability of the first crystal structure of a bacterial member (SLC26Dg) of the solute carrier SLC26 family of anion transporters has allowed us to create 3-dimensional models of all 10 human members (SLC26A1-A11, A10 being a pseudogene) of these membrane proteins using the Phyre2 bioinformatic tool. The homology modeling predicted that the SLC26 human proteins, like the SLC26Dg template, all consist of 14 transmembrane segments (TM) arranged in a 7+7 inverted topology with the amino-termini of two half-helices (TM3 and 10) facing each other in the centre of the protein to create the anion-binding site, linked to a C-terminal cytosolic sulfate transporter anti-sigma factor antagonist (STAS) domain. A plethora of human diseases are associated with mutations in the genes encoding human SLC26 transporters, including chondrodysplasias with varying severity in SLC26A2 (~50 mutations, 27 point mutations), congenital chloride-losing diarrhea in SLC26A3 (~70 mutations, 31 point mutations) and Pendred Syndrome or deafness autosomal recessive type 4 in SLC26A4 (~500 mutations, 203 point mutations). We have localized all of these point mutations in the 3-dimensional structures of the respective SLC26A2, A3 and A4 proteins and systematically analyzed their effect on protein structure. While most disease-causing mutations may cause folding defects resulting in impaired trafficking of these membrane glycoproteins from the endoplasmic reticulum to the cell surface - as demonstrated in a number of functional expression studies - the modeling also revealed that a number of pathogenic mutations are localized to the anion-binding site, which may directly affect transport function.
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Affiliation(s)
- Chloe Rapp
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Xiaoyun Bai
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Krishnan V, Maddox JW, Rodriguez T, Gleason E. A role for the cystic fibrosis transmembrane conductance regulator in the nitric oxide-dependent release of Cl - from acidic organelles in amacrine cells. J Neurophysiol 2017; 118:2842-2852. [PMID: 28835528 DOI: 10.1152/jn.00511.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 12/16/2022] Open
Abstract
γ-Amino butyric acid (GABA) and glycine typically mediate synaptic inhibition because their ligand-gated ion channels support the influx of Cl- However, the electrochemical gradient for Cl- across the postsynaptic plasma membrane determines the voltage response of the postsynaptic cell. Typically, low cytosolic Cl- levels support inhibition, whereas higher levels of cytosolic Cl- can suppress inhibition or promote depolarization. We previously reported that nitric oxide (NO) releases Cl- from acidic organelles and transiently elevates cytosolic Cl-, making the response to GABA and glycine excitatory. In this study, we test the hypothesis that the cystic fibrosis transmembrane conductance regulator (CFTR) is involved in the NO-dependent efflux of organellar Cl- We first establish the mRNA and protein expression of CFTR in our model system, cultured chick retinal amacrine cells. Using whole cell voltage-clamp recordings of currents through GABA-gated Cl- channels, we examine the effects of pharmacological inhibition of CFTR on the NO-dependent release of internal Cl- To interfere with the expression of CFTR, we used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing. We find that both pharmacological inhibition and CRISPR/Cas9-mediated knockdown of CFTR block the ability of NO to release Cl- from internal stores. These results demonstrate that CFTR is required for the NO-dependent efflux of Cl- from acidic organelles.NEW & NOTEWORTHY Although CFTR function has been studied extensively in the context of epithelia, relatively little is known about its function in neurons. We show that CFTR is involved in an NO-dependent release of Cl- from acidic organelles. This internal function of CFTR is particularly relevant to neuronal physiology because postsynaptic cytosolic Cl- levels determine the outcome of GABA- and glycinergic synaptic signaling. Thus the CFTR may play a role in regulating synaptic transmission.
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Affiliation(s)
- Vijai Krishnan
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - J Wesley Maddox
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Tyler Rodriguez
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Evanna Gleason
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
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Bicarbonate in cystic fibrosis. J Cyst Fibros 2017; 16:653-662. [PMID: 28732801 DOI: 10.1016/j.jcf.2017.06.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/22/2017] [Accepted: 06/22/2017] [Indexed: 11/20/2022]
Abstract
BACKGROUND Cystic fibrosis (CF, mucoviscidosis) is caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), which is a chloride and bicarbonate channel necessary for fluid secretion and extracellular alkalization. For a long time, research concentrated on abnormal Cl- and Na+ transport, but neglected bicarbonate as a crucial factor in CF. METHODS The present short review reports early findings as well as recent insights into the role of CFTR for bicarbonate transport and its defects in CF. RESULTS The available data indicate impaired bicarbonate transport not only in pancreas, intestine, airways, and reproductive organs, but also in salivary glands, sweat duct and renal tubular epithelial cells. Defective bicarbonate transport is closely related to the impaired mucus properties and mucus blocking in secretory organs of CF patients, causing the life threatening lung disease. CONCLUSIONS Apart from the devastating lung disease, abrogated bicarbonate transport also leads to many other organ dysfunctions, which are outlined in the present review.
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Broadbent D, Ahmadzai MM, Kammala AK, Yang C, Occhiuto C, Das R, Subramanian H. Roles of NHERF Family of PDZ-Binding Proteins in Regulating GPCR Functions. Adv Immunol 2017; 136:353-385. [PMID: 28950951 DOI: 10.1016/bs.ai.2017.05.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Multicellular organisms are equipped with an array of G-protein-coupled receptors (GPCRs) that mediate cell-cell signaling allowing them to adapt to environmental cues and ultimately survive. This is mechanistically possible through complex intracellular GPCR machinery that encompasses a vast network of proteins. Within this network, there is a group called scaffolding proteins that facilitate proper localization of signaling proteins for a quick and robust GPCR response. One protein family within this scaffolding group is the PSD-95/Dlg/ZO-1 (PDZ) family which is important for GPCR localization, internalization, recycling, and downstream signaling. Although the PDZ family of proteins regulate the functions of several receptors, this chapter focuses on a subfamily within the PDZ protein family called the Na+/H+ exchanger regulatory factors (NHERFs). Here we extensively review the predominantly characterized roles of NHERFs in renal phosphate absorption, intestinal ion regulation, cancer progression, and immune cell functions. Finally, we discuss the future perspectives and possible clinical application of targeting NHERFs in several disorders.
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Affiliation(s)
| | | | | | - Canchai Yang
- Michigan State University, East Lansing, MI, United States
| | | | - Rupali Das
- Michigan State University, East Lansing, MI, United States
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Yamaguchi M, Steward MC, Smallbone K, Sohma Y, Yamamoto A, Ko SBH, Kondo T, Ishiguro H. Bicarbonate-rich fluid secretion predicted by a computational model of guinea-pig pancreatic duct epithelium. J Physiol 2017; 595:1947-1972. [PMID: 27995646 DOI: 10.1113/jp273306] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 11/24/2016] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS The ductal system of the pancreas secretes large volumes of alkaline fluid containing HCO3- concentrations as high as 140 mm during hormonal stimulation. A computational model has been constructed to explore the underlying ion transport mechanisms. Parameters were estimated by fitting the model to experimental data from guinea-pig pancreatic ducts. The model was readily able to secrete 140 mm HCO3- . Its capacity to do so was not dependent upon special properties of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channels and solute carrier family 26 member A6 (SLC26A6) anion exchangers. We conclude that the main requirement for secreting high HCO3- concentrations is to minimize the secretion of Cl- ions. These findings help to clarify the mechanism responsible for pancreatic HCO3- secretion, a vital process that prevents the formation of protein plugs and viscous mucus in the ducts, which could otherwise lead to pancreatic disease. ABSTRACT A computational model of guinea-pig pancreatic duct epithelium was developed to determine the transport mechanism by which HCO3- ions are secreted at concentrations in excess of 140 mm. Parameters defining the contributions of the individual ion channels and transporters were estimated by least-squares fitting of the model predictions to experimental data obtained from isolated ducts and intact pancreas under a range of experimental conditions. The effects of cAMP-stimulated secretion were well replicated by increasing the activities of the basolateral Na+ -HCO3- cotransporter (NBC1) and apical Cl- /HCO3- exchanger (solute carrier family 26 member A6; SLC26A6), increasing the basolateral K+ permeability and apical Cl- and HCO3- permeabilities (CFTR), and reducing the activity of the basolateral Cl- /HCO3- exchanger (anion exchanger 2; AE2). Under these conditions, the model secreted ∼140 mm HCO3- at a rate of ∼3 nl min-1 mm-2 , which is consistent with experimental observations. Alternative 1:2 and 1:1 stoichiometries for Cl- /HCO3- exchange via SLC26A6 at the apical membrane were able to support a HCO3- -rich secretion. Raising the HCO3- /Cl- permeability ratio of CFTR from 0.4 to 1.0 had little impact upon either the secreted HCO3- concentration or the volume flow. However, modelling showed that a reduction in basolateral AE2 activity by ∼80% was essential in minimizing the intracellular Cl- concentration following cAMP stimulation and thereby maximizing the secreted HCO3- concentration. The addition of a basolateral Na+ -K+ -2Cl- cotransporter (NKCC1), assumed to be present in rat and mouse ducts, raised intracellular Cl- and resulted in a lower secreted HCO3- concentration, as is characteristic of those species. We conclude therefore that minimizing the driving force for Cl- secretion is the main requirement for secreting 140 mm HCO3- .
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Affiliation(s)
- Makoto Yamaguchi
- Department of Human Nutrition, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | | | - Kieran Smallbone
- School of Computer Science, University of Manchester, Manchester, UK
| | | | - Akiko Yamamoto
- Department of Human Nutrition, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shigeru B H Ko
- Department of Systems Medicine, Keio University, Tokyo, Japan
| | - Takaharu Kondo
- Department of Human Nutrition, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Ishiguro
- Department of Human Nutrition, Nagoya University Graduate School of Medicine, Nagoya, Japan
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The role of intestinal oxalate transport in hyperoxaluria and the formation of kidney stones in animals and man. Urolithiasis 2016; 45:89-108. [PMID: 27913853 DOI: 10.1007/s00240-016-0952-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/22/2016] [Indexed: 12/26/2022]
Abstract
The intestine exerts a considerable influence over urinary oxalate in two ways, through the absorption of dietary oxalate and by serving as an adaptive extra-renal pathway for elimination of this waste metabolite. Knowledge of the mechanisms responsible for oxalate absorption and secretion by the intestine therefore have significant implications for understanding the etiology of hyperoxaluria, as well as offering potential targets for future treatment strategies for calcium oxalate kidney stone disease. In this review, we present the recent developments and advances in this area over the past 10 years, and put to the test some of the new ideas that have emerged during this time, using human and mouse models. A key focus for our discussion are the membrane-bound anion exchangers, belonging to the SLC26 gene family, some of which have been shown to participate in transcellular oxalate absorption and secretion. This has offered the opportunity to not only examine the roles of these specific transporters, revealing their importance to oxalate homeostasis, but to also probe the relative contributions made by the active transcellular and passive paracellular components of oxalate transport across the intestine. We also discuss some of the various physiological stimuli and signaling pathways which have been suggested to participate in the adaptation and regulation of intestinal oxalate transport. Finally, we offer an update on research into Oxalobacter formigenes, alongside recent investigations of other oxalate-degrading gut bacteria, in both laboratory animals and humans.
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Saint-Criq V, Gray MA. Role of CFTR in epithelial physiology. Cell Mol Life Sci 2016; 74:93-115. [PMID: 27714410 PMCID: PMC5209439 DOI: 10.1007/s00018-016-2391-y] [Citation(s) in RCA: 242] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/20/2022]
Abstract
Salt and fluid absorption and secretion are two processes that are fundamental to epithelial function and whole body fluid homeostasis, and as such are tightly regulated in epithelial tissues. The CFTR anion channel plays a major role in regulating both secretion and absorption in a diverse range of epithelial tissues, including the airways, the GI and reproductive tracts, sweat and salivary glands. It is not surprising then that defects in CFTR function are linked to disease, including life-threatening secretory diarrhoeas, such as cholera, as well as the inherited disease, cystic fibrosis (CF), one of the most common life-limiting genetic diseases in Caucasian populations. More recently, CFTR dysfunction has also been implicated in the pathogenesis of acute pancreatitis, chronic obstructive pulmonary disease (COPD), and the hyper-responsiveness in asthma, underscoring its fundamental role in whole body health and disease. CFTR regulates many mechanisms in epithelial physiology, such as maintaining epithelial surface hydration and regulating luminal pH. Indeed, recent studies have identified luminal pH as an important arbiter of epithelial barrier function and innate defence, particularly in the airways and GI tract. In this chapter, we will illustrate the different operational roles of CFTR in epithelial function by describing its characteristics in three different tissues: the airways, the pancreas, and the sweat gland.
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Affiliation(s)
- Vinciane Saint-Criq
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, University Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH UK
| | - Michael A. Gray
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, University Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH UK
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