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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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Abstract
PURPOSE OF REVIEW We recently localized a new K-Cl cotransporters-3 (KCC3) transporter to the apical membrane of type-B intercalated cells. This gives us an opportunity to revisit the roles of the KCC3 in kidney and integrate the new findings to our current knowledge of the biology of the bicarbonate secreting cells. RECENT FINDINGS Here, we review the basic properties of the K-Cl cotransporter with a particular attention to the responsiveness of the transporter to cell swelling. We summarize what is already known about KCC3b and discuss new information gained from our localizing of KCC3a in type-B intercalated cells. We integrate the physiology of KCC3a with the main function of the type-B cell, that is, bicarbonate secretion through the well characterized apical Cl-/HCO3- exchanger and the basolateral Na-HCO3 cotransporter. SUMMARY Both KCC3b and KCC3a seem to be needed for maintaining cell volume during enhanced inward cotransport of Na-glucose in proximal tubule and Na-HCO3 in intercalated cells. In addition, apical KCC3a might couple to pendrin function to recycle Cl-, particularly in conditions of low salt diet and therefore low Cl- delivery to the distal tubule. This function is critical in alkalemia, and KCC3a function in the pendrin-expressing cells may contribute to the K+ loss which is observed in alkalemia.
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Affiliation(s)
- Mohammed Z Ferdaus
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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3
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Verlander JW, Lee HW, Wall SM, Harris AN, Weiner ID. The proximal tubule through an NBCe1-dependent mechanism regulates collecting duct phenotypic and remodeling responses to acidosis. Am J Physiol Renal Physiol 2023; 324:F12-F29. [PMID: 36264886 PMCID: PMC9762982 DOI: 10.1152/ajprenal.00175.2022] [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: 06/27/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 02/04/2023] Open
Abstract
The renal response to acid-base disturbances involves phenotypic and remodeling changes in the collecting duct. This study examines whether the proximal tubule controls these responses. We examined mice with genetic deletion of proteins present only in the proximal tubule, either the A variant or both A and B variants of isoform 1 of the electrogenic Na+-bicarbonate cotransporter (NBCe1). Both knockout (KO) mice have spontaneous metabolic acidosis. We then determined the collecting duct phenotypic responses to this acidosis and the remodeling responses to exogenous acid loading. Despite the spontaneous acidosis in NBCe1-A KO mice, type A intercalated cells in the inner stripe of the outer medullary collecting duct (OMCDis) exhibited decreased height and reduced expression of H+-ATPase, anion exchanger 1, Rhesus B glycoprotein, and Rhesus C glycoprotein. Combined kidney-specific NBCe1-A/B deletion induced similar changes. Ultrastructural imaging showed decreased apical plasma membrane and increased vesicular H+-ATPase in OMCDis type A intercalated cell in NBCe1-A KO mice. Next, we examined the collecting duct remodeling response to acidosis. In wild-type mice, acid loading increased the proportion of type A intercalated cells in the connecting tubule (CNT) and OMCDis, and it decreased the proportion of non-A, non-B intercalated cells in the connecting tubule, and type B intercalated cells in the cortical collecting duct (CCD). These changes were absent in NBCe1-A KO mice. We conclude that the collecting duct phenotypic and remodeling responses depend on proximal tubule-dependent signaling mechanisms blocked by constitutive deletion of proximal tubule NBCe1 proteins.NEW & NOTEWORTHY This study shows that the proximal tubule regulates collecting duct phenotypic and remodeling responses to acidosis.
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Affiliation(s)
- Jill W Verlander
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Susan M Wall
- Renal Division, Emory University, Atlanta, Georgia
| | - Autumn N Harris
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Deparment of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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Abstract
Intercalated cells make up about a third of all cells within the connecting tubule and the collecting duct and are subclassified as type A, type B and non-A, non-B based on the subcellular distribution of the H+-ATPase, which dictates whether it secretes H+ or HCO3-. Type B intercalated cells mediate Cl- absorption and HCO3- secretion, which occurs largely through the anion exchanger pendrin. Pendrin is stimulated by angiotensin II via the angiotensin type 1a receptor and by aldosterone through MR (mineralocorticoid receptor). Aldosterone stimulates pendrin expression and function, in part, through the alkalosis it generates. Pendrin-mediated HCO3- secretion increases in models of metabolic alkalosis, which attenuates the alkalosis. However, pendrin-positive intercalated cells also regulate blood pressure, at least partly, through pendrin-mediated Cl- absorption and through their indirect effect on the epithelial Na+ channel, ENaC. This aldosterone-induced increase in pendrin secondarily stimulates ENaC, thereby contributing to the aldosterone pressor response. This review describes the contribution of pendrin-positive intercalated cells to Na+, K+, Cl- and acid-base balance.
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Affiliation(s)
- Susan M Wall
- Department of Medicine, Emory University School of Medicine, Atlanta, GA
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Shah VS, Chivukula RR, Lin B, Waghray A, Rajagopal J. Cystic Fibrosis and the Cells of the Airway Epithelium: What Are Ionocytes and What Do They Do? ANNUAL REVIEW OF PATHOLOGY 2022; 17:23-46. [PMID: 34437820 PMCID: PMC10837786 DOI: 10.1146/annurev-pathol-042420-094031] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cystic fibrosis (CF) is caused by defects in an anion channel, the cystic fibrosis transmembrane conductance regulator (CFTR). Recently, a new airway epithelial cell type has been discovered and dubbed the pulmonary ionocyte. Unexpectedly, these ionocytes express higher levels of CFTR than any other airway epithelial cell type. However, ionocytes are not the sole CFTR-expressing airway epithelial cells, and CF-associated disease genes are in fact expressed in multiple airway epithelial cell types. The experimental depletion of ionocytes perturbs epithelial physiology in the mouse trachea, but the role of these rare cells in the pathogenesis of human CF remains mysterious. Ionocytes have been described in diverse tissues(kidney and inner ear) and species (frog and fish). We draw on these prior studies to suggest potential roles of airway ionocytes in health and disease. A complete understanding of ionocytes in the mammalian airway will ultimately depend on cell type-specific genetic manipulation.
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Affiliation(s)
- Viral S Shah
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; , , , ,
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Raghu R Chivukula
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; , , , ,
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
| | - Brian Lin
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; , , , ,
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
| | - Avinash Waghray
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; , , , ,
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
| | - Jayaraj Rajagopal
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; , , , ,
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA
- Klarman Cell Observatory, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA
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Silva PHI, Wiegand A, Daryadel A, Russo G, Ritter A, Gaspert A, Wüthrich RP, Wagner CA, Mohebbi N. Acidosis and alkali therapy in patients with kidney transplant is associated with transcriptional changes and altered abundance of genes involved in cell metabolism and acid-base balance. Nephrol Dial Transplant 2021; 36:1806-1820. [PMID: 34240183 DOI: 10.1093/ndt/gfab210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Metabolic acidosis occurs frequently in patients with kidney transplant and is associated with higher risk for and accelerated loss of graft function. To date, it is not known whether alkali therapy in these patients improves kidney function and whether acidosis and its therapy is associated with altered expression of proteins involved in renal acid-base metabolism. METHODS We collected retrospectively kidney biopsies from 22 patients. Of these patients, 9 had no acidosis, 9 had metabolic acidosis (plasma HCO3- < 22 mmol/l), and 4 had acidosis and received alkali therapy. We performed transcriptome analysis and immunohistochemistry for proteins involved in renal acid-base handling. RESULTS We found the expression of 40 transcripts significantly changed between kidneys from non-acidotic and acidotic patients. These genes are mostly involved in proximal tubule amino acid and lipid metabolism and energy homeostasis. Three transcripts were fully recovered by alkali therapy: the Kir4.2 K+-channel, an important regulator of proximal tubule HCO3--metabolism and transport, ACADSB and SHMT1, genes involved in beta-oxidation and methionine metabolism. Immunohistochemistry showed reduced staining for the proximal tubule NBCe1 HCO3- transporter in kidneys from acidotic patients that recovered with alkali therapy. In addition, the HCO3-exchanger pendrin was affected by acidosis and alkali therapy. CONCLUSIONS Metabolic acidosis in kidney transplant recipients is associated with alterations in the renal transcriptome that are partly restored by alkali therapy. Acid-base transport proteins mostly from proximal tubule were also affected by acidosis and alkali therapy suggesting that the downregulation of critical players contributes to metabolic acidosis in these patients.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Anna Wiegand
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Arezoo Daryadel
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Giancarlo Russo
- Functional Genomics Center Zürich, University of Zürich and ETH Zürich, Zürich, Switzerland
| | - Alexander Ritter
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Ariana Gaspert
- Department of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Rudolf P Wüthrich
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
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Tan Y, Chen M, Chen H, Wu J, Liu J. Enhanced Ultrasound Contrast of Renal-Clearable Luminescent Gold Nanoparticles. Angew Chem Int Ed Engl 2021; 60:11713-11717. [PMID: 33665956 DOI: 10.1002/anie.202017273] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/14/2021] [Indexed: 12/31/2022]
Abstract
Renal-clearable nanoparticles are typically fast eliminated through the free glomerular filtration, which show weak interaction with the renal compartments and negligible ultrasound signals, raising challenges in direct imaging of kidney diseases. Here, we report the ultrasmall renal-clearable luminescent gold nanoparticles (AuNPs) with both pH-induced charge reversal and aggregation properties, and discover that enhanced ultrasound contrast could be facilely acquired through the increased tubular reabsorption and in situ aggregation of AuNPs in renal tubule cells in injured kidneys. The tuning elimination pathway of the renal-clearable luminescent AuNPs is further demonstrated to provide a synergistical fluorescence and ultrasound imaging strategy for diagnosing early kidney injury with precise anatomical information.
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Affiliation(s)
- Yue Tan
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Miaona Chen
- Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Huarui Chen
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Juefei Wu
- Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Jinbin Liu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
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Tan Y, Chen M, Chen H, Wu J, Liu J. Enhanced Ultrasound Contrast of Renal‐Clearable Luminescent Gold Nanoparticles. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202017273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Yue Tan
- Key Laboratory of Functional Molecular Engineering of Guangdong Province School of Chemistry and Chemical Engineering South China University of Technology Guangzhou 510640 China
| | - Miaona Chen
- Department of Cardiology Nanfang Hospital Southern Medical University Guangzhou 510515 China
| | - Huarui Chen
- Key Laboratory of Functional Molecular Engineering of Guangdong Province School of Chemistry and Chemical Engineering South China University of Technology Guangzhou 510640 China
| | - Juefei Wu
- Department of Cardiology Nanfang Hospital Southern Medical University Guangzhou 510515 China
| | - Jinbin Liu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province School of Chemistry and Chemical Engineering South China University of Technology Guangzhou 510640 China
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Berg P, Svendsen SL, Hoang TTL, Praetorius HA, Sorensen MV, Leipziger J. Impaired renal HCO 3 - secretion in CFTR deficient mice causes metabolic alkalosis during chronic base-loading. Acta Physiol (Oxf) 2021; 231:e13591. [PMID: 33270356 DOI: 10.1111/apha.13591] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 12/11/2022]
Abstract
AIM Cystic fibrosis patients have an increased risk of developing metabolic alkalosis presumably as a result of altered renal HCO3 - handling. In this study, we directly assess the kidneys' ability to compensate for a chronic base-load in the absence of functional CFTR. METHODS Comprehensive urine and blood acid-base analyses were done in anaesthetized WT mice or mice lacking either CFTR or pendrin, with or without 7 days of oral NaHCO3 loading. The in vivo experiments were complemented by a combination of immunoblotting and experiments with perfused isolated mouse cortical collecting ducts (CCD). RESULTS Base-loaded WT mice maintained acid-base homeostasis by elevating urinary pH and HCO3 - excretion and decreasing urinary net acid excretion. In contrast, pendrin KO mice and CFTR KO mice were unable to increase urinary pH and HCO3 - excretion and unable to decrease urinary net acid excretion sufficiently and thus developed metabolic alkalosis in response to the same base-load. The expression of pendrin was increased in response to the base-load in WT mice with a paralleled increased pendrin function in the perfused CCD. In CFTR KO mice, 7 days of base-loading did not upregulate pendrin expression and apical Cl- /HCO3 - exchange function was strongly blunted in the CCD. CONCLUSION CFTR KO mice develop metabolic alkalosis during a chronic base-load because they are unable to sufficiently elevate renal HCO3 - excretion. This can be explained by markedly reduced pendrin function in the absence of CFTR.
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Affiliation(s)
- Peder Berg
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Samuel L. Svendsen
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Thi Thuy Linh Hoang
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Helle A. Praetorius
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Mads V. Sorensen
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Jens Leipziger
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
- Aarhus Institute of Advanced Studies Aarhus University Aarhus C Denmark
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Aljaylani A, Fluitt M, Piselli A, Shepard BD, Tiwari S, Ecelbarger CM. Acid Loading Unmasks Glucose Homeostatic Instability in Proximal-Tubule-Targeted Insulin/Insulin-Like-Growth-Factor-1 Receptor Dual Knockout Mice. Cell Physiol Biochem 2021; 54:682-695. [PMID: 32678535 DOI: 10.33594/000000248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2020] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND/AIMS Metabolic syndrome and type 2 diabetes are associated with some degree of acidosis. Acidosis has also been shown to upregulate renal gluconeogenesis. Whether impaired insulin or insulin-like-growth factor 1 receptor (IGF1) signaling alter this relationship is not known. Our aim was to determine the effects of deletion of insulin and IGF1 receptors (Insr and Igf1r) from renal proximal tubule (PT) on the gluconeogenic response to acidosis. METHODS We developed a mouse model with PT-targeted dual knockout (KO) of the Insr/Igf1r by driving Cre-recombinase with the gamma-glutamyl transferase (gGT) promoter. Male and female mice were maintained as control or acidotic by treatment with NH4Cl in the drinking water for 1-week. RESULTS Acidosis in both genotypes increased renal expression of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1-bisphosphatase (FBP1), but not glucose-6-phosphatase catalytic subunit (G6PC), which showed significantly lower expression in the KO regardless of treatment. Several differences between KO and WT suggested a protective role for insulin/IGF1 receptor signaling in maintaining relative euglycemia in the face of acidosis. First, the increase in FBP1 with acid was greater in the KO (significant interactive term). Secondly, proximal-tubule-associated FOXO1 and AKT overall protein levels were suppressed by acid loading in the KO, but not in the WT. Robust intact insulin signaling would be needed to reduce gluconeogenesis in PT. Third, phosphorylated FOXO1 (pS256) levels were markedly reduced by acid loading in the KO PT, but not in the WT. This reduction would support greater gluconeogenesis. Fourth, the sodium-glucose cotransporter (SGLT1) was increased by acid loading in the KO kidney, but not the WT. While this would not necessarily affect gluconeogenesis, it could result in increased circulatory glucose via renal reabsorption. Reduced susceptibility to glucose-homeostatic dysregulation in the WT could potentially relate to the sharp (over 50%) reduction in renal levels of sirtuin-1 (SIRT1), which deacetylates and regulates transcription of a number of genes. This reduction was absent in the KO. CONCLUSION Insulin resistance of the kidney may increase whole-body glucose instability a major risk factor for morbidity in diabetes. High dietary acid loads provide a dilemma for the kidney, as ammoniagenesis liberates α-ketoglutarate, which is a substrate for gluconeogenesis. We demonstrate an important role for insulin and/or IGF1 receptor signaling in the PT to facilitate this process and reduce excursions in blood glucose. Thus, medications and lifestyle changes that improve renal insulin sensitivity may also provide added benefit in type 2 diabetes especially when coupled with metabolic acidosis.
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Affiliation(s)
- Abdullah Aljaylani
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA
| | - Maurice Fluitt
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA
| | - Alexandra Piselli
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA
| | - Blythe D Shepard
- School of Nursing and Health Studies, Department of Human Science, Georgetown University, Washington, D.C., USA
| | - Swasti Tiwari
- Department of Molecular Medicine & Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Utter Pradesh, India
| | - Carolyn M Ecelbarger
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA,
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Lee JU, Lee HJ, Kim JN, Kim MK, Kim SR, Chang HS, Park CS, Park JS. Effects of Ammonium Chloride on Ozone-induced Airway Inflammation: the Role of Slc26a4 in the Lungs of Mice. J Korean Med Sci 2020; 35:e272. [PMID: 32808511 PMCID: PMC7431289 DOI: 10.3346/jkms.2020.35.e272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 06/24/2020] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Exposure to ozone (O₃) induces neutrophilic inflammation and goblet cell hyperplasia in humans and experimental animals. Because the solute carrier family 26-member 4 (Slc26a4; pendrin) gene induces mucin production and intraluminal acidification in the airways, it was hypothesized to be a key molecule in O₃-induced airway injury. Thus, we evaluated the role of Slc26a4 and the protective effects of ammonium chloride (NH₄Cl) in O₃-induced airway injury in mice. METHODS Six-week-old female BALB/c mice were exposed to filtered air or O₃ for 21 days (2 ppm for 3 hr/day). NH₄Cl (0, 0.1, 1, and 10 mM) was administered intratracheally into the airways. Airway resistance was measured using a flexiVent system, and bronchoalveolar lavage fluid (BALF) cells were differentially counted. Slc26a4 and Muc5ac proteins and mRNA were measured via western blotting, real-time polymerase chain reaction, and immunostaining. Tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-17, IL-1β, and caspase-1 were analyzed via western blotting. RESULTS The levels Slc26a4 protein and mRNA significantly increased in lung tissues from Day 7 to Day 21 of O₃ exposure, with concomitant increases in lung resistance, numbers of goblet cells in lung tissues, and inflammatory cells and thiocyanate (SCN-) levels in BALF in a time-dependent manner. Treatment with NH₄Cl significantly reduced these changes to levels similar to those of sham-treated mice, with a concomitant reduction of Slc26a4 proteins in lung lysates and SCN- levels in BALF. Slc26a4 protein was co-expressed with muc5ac protein in the bronchial epithelium, as indicated by immunofluorescence staining. NH₄Cl treatment also significantly attenuated the O₃-induced increases in IFN-γ, TNF-α, IL-17, IL-1β, and p20-activated caspase-1. CONCLUSION Slc26a4 may be involved in O₃-induced inflammatory and epithelial changes in the airways via activation of the inflammasome and the induction of IL-17 and IFN-γ. NH₄Cl shows a potential as a therapeutic agent for controlling O₃-induced airway inflammation and epithelial damage by modulating Slc26a4 expression.
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Affiliation(s)
- Jong Uk Lee
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Hyeon Ju Lee
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Ji Na Kim
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Min Kyung Kim
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Sung Roul Kim
- Department of Environmental Health Sciences, Soonchunhyang University, Asan, Korea
| | - Hun Soo Chang
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
- Soonchunhyang Medical Research Institute, Soonchunhyang University College of Medicine, Cheonan, Korea
| | - Choon Sik Park
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Jong Sook Park
- Division of Allergy and Respiratory Diseases, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
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Wall SM, Verlander JW, Romero CA. The Renal Physiology of Pendrin-Positive Intercalated Cells. Physiol Rev 2020; 100:1119-1147. [PMID: 32347156 PMCID: PMC7474261 DOI: 10.1152/physrev.00011.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Intercalated cells (ICs) are found in the connecting tubule and the collecting duct. Of the three IC subtypes identified, type B intercalated cells are one of the best characterized and known to mediate Cl- absorption and HCO3- secretion, largely through the anion exchanger pendrin. This exchanger is thought to act in tandem with the Na+-dependent Cl-/HCO3- exchanger, NDCBE, to mediate net NaCl absorption. Pendrin is stimulated by angiotensin II and aldosterone administration via the angiotensin type 1a and the mineralocorticoid receptors, respectively. It is also stimulated in models of metabolic alkalosis, such as with NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, of probably more physiological or clinical significance is the role of these pendrin-positive ICs in blood pressure regulation, which occurs, at least in part, through pendrin-mediated renal Cl- absorption, as well as their effect on the epithelial Na+ channel, ENaC. Aldosterone stimulates ENaC directly through principal cell mineralocorticoid hormone receptor (ligand) binding and also indirectly through its effect on pendrin expression and function. In so doing, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. In addition to its role in Na+ and Cl- balance, pendrin affects the balance of other ions, such as K+ and I-. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contribution of pendrin-positive ICs in the kidney to distal nephron function and blood pressure.
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Affiliation(s)
- Susan M Wall
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Jill W Verlander
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Cesar A Romero
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
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Ayuzawa N, Nishimoto M, Ueda K, Hirohama D, Kawarazaki W, Shimosawa T, Marumo T, Fujita T. Two Mineralocorticoid Receptor-Mediated Mechanisms of Pendrin Activation in Distal Nephrons. J Am Soc Nephrol 2020; 31:748-764. [PMID: 32034107 DOI: 10.1681/asn.2019080804] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/27/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Regulation of sodium chloride transport in the aldosterone-sensitive distal nephron is essential for fluid homeostasis and BP control. The chloride-bicarbonate exchanger pendrin in β-intercalated cells, along with sodium chloride cotransporter (NCC) in distal convoluted tubules, complementarily regulate sodium chloride handling, which is controlled by the renin-angiotensin-aldosterone system. METHODS Using mice with mineralocorticoid receptor deletion in intercalated cells, we examined the mechanism and roles of pendrin upregulation via mineralocorticoid receptor in two different models of renin-angiotensin-aldosterone system activation. We also used aldosterone-treated NCC knockout mice to examine the role of pendrin regulation in salt-sensitive hypertension. RESULTS Deletion of mineralocorticoid receptor in intercalated cells suppressed the increase in renal pendrin expression induced by either exogenous angiotensin II infusion or endogenous angiotensin II upregulation via salt restriction. When fed a low-salt diet, intercalated cell-specific mineralocorticoid receptor knockout mice with suppression of pendrin upregulation showed BP reduction that was attenuated by compensatory activation of NCC. In contrast, upregulation of pendrin induced by aldosterone excess combined with a high-salt diet was scarcely affected by deletion of mineralocorticoid receptor in intercalated cells, but depended instead on hypokalemic alkalosis through the activated mineralocorticoid receptor-epithelial sodium channel cascade in principal cells. In aldosterone-treated NCC knockout mice showing upregulation of pendrin, potassium supplementation corrected alkalosis and inhibited the pendrin upregulation, thereby lowering BP. CONCLUSIONS In conjunction with NCC, the two pathways of pendrin upregulation, induced by angiotensin II through mineralocorticoid receptor activation in intercalated cells and by alkalosis through mineralocorticoid receptor activation in principal cells, play important roles in fluid homeostasis during salt depletion and salt-sensitive hypertension mediated by aldosterone excess.
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Affiliation(s)
- Nobuhiro Ayuzawa
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan;
| | - Mitsuhiro Nishimoto
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Kohei Ueda
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Daigoro Hirohama
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Wakako Kawarazaki
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Tatsuo Shimosawa
- Department of Clinical Laboratory, School of Medicine, International University of Health and Welfare, Chiba, Japan
| | - Takeshi Marumo
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan;
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Himmel NJ, Wang Y, Rodriguez DA, Sun MA, Blount MA. Chronic lithium treatment induces novel patterns of pendrin localization and expression. Am J Physiol Renal Physiol 2018; 315:F313-F322. [PMID: 29667915 PMCID: PMC6139525 DOI: 10.1152/ajprenal.00065.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/04/2018] [Accepted: 04/12/2018] [Indexed: 12/25/2022] Open
Abstract
Prolonged lithium treatment is associated with various renal side effects and is known to induce inner medullary collecting duct (IMCD) remodeling. In animals treated with lithium, the fraction of intercalated cells (ICs), which are responsible for acid-base homeostasis, increases compared with renal principal cells (PCs). To investigate the intricacies of lithium-induced IMCD remodeling, male Sprague-Dawley rats were fed a lithium-enriched diet for 0,1, 2, 3, 6, 9, or 12 wk. Urine osmolality was decreased at 1 wk, and from 2 to 12 wk, animals were severely polyuric. After 6 wk of lithium treatment, approximately one-quarter of the cells in the initial IMCD expressed vacuolar H+-ATPase, an IC marker. These cells were localized in portions of the inner medulla, where ICs are not normally found. Pendrin, a Cl-/[Formula: see text] exchanger, is normally expressed only in two IC subtypes found in the convoluted tubule, the cortical collecting duct, and the connecting tubule. At 6 wk of lithium treatment, we observed various patterns of pendrin localization and expression in the rat IMCD, including a novel phenotype wherein pendrin was coexpressed with aquaporin-4. These observations collectively suggest that renal IMCD cell plasticity may play an important role in lithium-induced IMCD remodeling.
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Affiliation(s)
- Nathaniel J Himmel
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Yirong Wang
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Daniel A Rodriguez
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Michael A Sun
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Mitsi A Blount
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
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Frische S, Chambrey R, Trepiccione F, Zamani R, Marcussen N, Alexander RT, Skjødt K, Svenningsen P, Dimke H. H +-ATPase B1 subunit localizes to thick ascending limb and distal convoluted tubule of rodent and human kidney. Am J Physiol Renal Physiol 2018; 315:F429-F444. [PMID: 29993276 DOI: 10.1152/ajprenal.00539.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The vacuolar-type H+-ATPase B1 subunit is heavily expressed in the intercalated cells of the collecting system, where it contributes to H+ transport, but has also been described in other segments of the renal tubule. This study aimed to determine the localization of the B1 subunit of the vacuolar-type H+-ATPase in the early distal nephron, encompassing thick ascending limbs (TAL) and distal convoluted tubules (DCT), in human kidney and determine whether the localization differs between rodents and humans. Antibodies directed against the H+-ATPase B1 subunit were used to determine its localization in paraffin-embedded formalin-fixed mouse, rat, and human kidneys by light microscopy and in sections of Lowicryl-embedded rat kidneys by electron microscopy. Abundant H+-ATPase B1 subunit immunoreactivity was observed in the human kidney. As expected, intercalated cells showed the strongest signal, but significant signal was also observed in apical membrane domains of the distal nephron, including TAL, macula densa, and DCT. In mouse and rat, H+-ATPase B1 subunit expression could also be detected in apical membrane domains of these segments. In rat, electron microscopy revealed that the H+-ATPase B1 subunit was located in the apical membrane. Furthermore, the H+-ATPase B1 subunit colocalized with other H+-ATPase subunits in the TAL and DCT. In conclusion, the B1 subunit is expressed in the early distal nephron. The physiological importance of H+-ATPase expression in these segments remains to be delineated in detail. The phenotype of disease-causing mutations in the B1 subunit may also relate to its presence in the TAL and DCT.
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Affiliation(s)
| | - Régine Chambrey
- INSERM 1188-Université de La Réunion, Sainte Clotilde, La Réunion, France
| | - Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli," Naples, Italy
| | - Reza Zamani
- Department of Urology, Odense University Hospital , Odense , Denmark
| | - Niels Marcussen
- Department of Clinical Pathology, Odense University Hospital , Odense , Denmark
| | - R Todd Alexander
- Department of Pediatrics, University of Alberta , Edmonton, Alberta , Canada.,Membrane Protein Disease Research Group, University of Alberta , Edmonton, Alberta , Canada
| | - Karsten Skjødt
- Department of Cancer and Inflammation, Institute of Molecular Medicine, University of Southern Denmark , Odense , Denmark
| | - Per Svenningsen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark , Odense , Denmark
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark , Odense , Denmark
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Wall SM. Renal intercalated cells and blood pressure regulation. Kidney Res Clin Pract 2017; 36:305-317. [PMID: 29285423 PMCID: PMC5743040 DOI: 10.23876/j.krcp.2017.36.4.305] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 12/12/2022] Open
Abstract
Type B and non-A, non-B intercalated cells are found within the connecting tubule and the cortical collecting duct. Of these cell types, type B intercalated cells are known to mediate Cl- absorption and HCO3- secretion largely through pendrin-dependent Cl-/HCO3- exchange. This exchange is stimulated by angiotensin II administration and is also stimulated in models of metabolic alkalosis, for instance after aldosterone or NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, the role of pendrin in blood pressure regulation is likely of more physiological or clinical significance. Pendrin regulates blood pressure not only by mediating aldosterone-sensitive Cl- absorption, but also by modulating the aldosterone response for epithelial Na+ channel (ENaC)-mediated Na+ absorption. Pendrin regulates ENaC through changes in open channel of probability, channel surface density, and channels subunit total protein abundance. Thus, aldosterone stimulates ENaC activity through both direct and indirect effects, the latter occurring through its stimulation of pendrin expression and function. Therefore, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contributory role of pendrin in distal nephron function and blood pressure.
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Affiliation(s)
- Susan M. Wall
- Departments of Medicine, Emory University School of Medicine, Atlanta, GA,
USA
- Physiology, Emory University School of Medicine, Atlanta, GA,
USA
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17
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Pathophysiology, diagnosis and treatment of inherited distal renal tubular acidosis. J Nephrol 2017; 31:511-522. [DOI: 10.1007/s40620-017-0447-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/21/2017] [Indexed: 10/18/2022]
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Acute regulated expression of pendrin in human urinary exosomes. Pflugers Arch 2017; 470:427-438. [PMID: 28803436 DOI: 10.1007/s00424-017-2049-0] [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] [Received: 06/14/2017] [Revised: 07/23/2017] [Accepted: 07/26/2017] [Indexed: 10/19/2022]
Abstract
It is well known that pendrin, an apical Cl-/HCO3-exchanger in type B intercalated cells, is modulated by chronic acid-base disturbances and electrolyte intake. To study this adaptation further at the acute level, we analyzed urinary exosomes from individuals subjected to oral acute acid, alkali, and NaCl loading. Acute oral NH4Cl loading (n = 8) elicited systemic acidemia with a drop in urinary pH and an increase in urinary NH4 excretion. Nadir urinary pH was achieved 5 h after NH4Cl loading. Exosomal pendrin abundance was dramatically decreased at 3 h after acid loading. In contrast, after acute equimolar oral NaHCO3 loading (n = 8), urinary and venous blood pH rose rapidly with a significant attenuation of urinary NH4 excretion. Alkali loading caused rapid upregulation of exosomal pendrin abundance at 1 h and normalized within 3 h of treatment. Equimolar NaCl loading (n = 6) did not alter urinary or venous blood pH or urinary NH4 excretion. However, pendrin abundance in urinary exosomes was significantly reduced at 2 h of NaCl ingestion with lowest levels observed at 4 h after treatment. In patients with inherited distal renal tubular acidosis (dRTA), pendrin abundance in urinary exosomes was greatly reduced and did not change upon oral NH4Cl loading. In summary, pendrin can be detected and quantified in human urinary exosomes by immunoblotting. Acid, alkali, and NaCl loadings cause acute changes in pendrin abundance in urinary exosomes within a few hours. Our data suggest that exosomal pendrin is a promising urinary biomarker for acute acid-base and volume status changes in humans.
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19
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Mineralocorticoid receptor as a therapeutic target in chronic kidney disease and hypertension. Hypertens Res 2016; 40:221-225. [DOI: 10.1038/hr.2016.137] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/08/2016] [Accepted: 09/08/2016] [Indexed: 01/29/2023]
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Cil O, Haggie PM, Phuan PW, Tan JA, Verkman AS. Small-Molecule Inhibitors of Pendrin Potentiate the Diuretic Action of Furosemide. J Am Soc Nephrol 2016; 27:3706-3714. [PMID: 27153921 DOI: 10.1681/asn.2015121312] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/18/2016] [Indexed: 11/03/2022] Open
Abstract
Pendrin is a Cl-/HCO3- exchanger expressed in type B and non-A, non-B intercalated cells in the distal nephron, where it facilitates Cl- absorption and is involved in Na+ absorption and acid-base balance. Pendrin-knockout mice show no fluid-electrolyte abnormalities under baseline conditions, although mice with double knockout of pendrin and the Na+/Cl- cotransporter (NCC) manifest profound salt wasting. Thus, pendrin may attenuate diuretic-induced salt loss, but this function remains unconfirmed. To clarify the physiologic role of pendrin under conditions not confounded by gene knockout, and to test the potential utility of pendrin inhibitors for diuretic therapy, we tested in mice a small-molecule pendrin inhibitor identified from a high-throughput screen. In vitro, a pyrazole-thiophenesulfonamide, PDSinh-C01, inhibited Cl-/anion exchange mediated by mouse pendrin with a 50% inhibitory concentration of 1-3 µM, without affecting other major kidney tubule transporters. Administration of PDSinh-C01 to mice at predicted therapeutic doses, determined from serum and urine pharmacokinetics, did not affect urine output, osmolality, salt excretion, or acid-base balance. However, in mice treated acutely with furosemide, administration of PDSinh-C01 produced a 30% increase in urine output, with increased Na+ and Cl- excretion. In mice treated long term with furosemide, in which renal pendrin is upregulated, PDSinh-C01 produced a 60% increase in urine output. Our findings clarify the role of pendrin in kidney function and suggest pendrin inhibition as a novel approach to potentiate the action of loop diuretics. Such combination therapy might enhance diuresis and salt excretion for treatment of hypertension and edema, perhaps including diuretic-resistant edema.
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Affiliation(s)
- Onur Cil
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Peter M Haggie
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Puay-Wah Phuan
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Joseph-Anthony Tan
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
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Osis G, Handlogten ME, Lee HW, Hering-Smith KS, Huang W, Romero MF, Verlander JW, Weiner ID. Effect of NBCe1 deletion on renal citrate and 2-oxoglutarate handling. Physiol Rep 2016; 4:e12778. [PMID: 27117802 PMCID: PMC4848728 DOI: 10.14814/phy2.12778] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 03/29/2016] [Accepted: 04/01/2016] [Indexed: 12/03/2022] Open
Abstract
UNLABELLED The bicarbonate transporter, NBCe1 (SLC4A4), is necessary for at least two components of the proximal tubule contribution to acid-base homeostasis, filtered bicarbonate reabsorption, and ammonia metabolism. This study's purpose was to determine NBCe1's role in a third component of acid-base homeostasis, organic anion metabolism, by studying mice with NBCe1 deletion. Because NBCe1 deletion causes metabolic acidosis, we also examined acid-loaded wild-type adult mice to determine if the effects of NBCe1 deletion were specific to NBCe1 deletion or were a non-specific effect of the associated metabolic acidosis. Both NBCe1 KO and acid-loading decreased citrate excretion, but in contrast to metabolic acidosis alone, NBCe1 KO decreased expression of the apical citrate transporter, NaDC-1. Thus, NBCe1 expression is necessary for normal NaDC-1 expression, and NBCe1 deletion induces a novel citrate reabsorptive pathway. Second, NBCe1 KO increased 2-oxoglutarate excretion. This could not be attributed to the metabolic acidosis as experimental acidosis decreased excretion. Increased 2-oxoglutarate excretion could not be explained by changes in plasma 2-oxoglutarate levels, the glutaminase I or the glutaminase II generation pathways, 2-oxoglutarate metabolism, its putative apical 2-oxoglutarate transporter, OAT10, or its basolateral transporter, NaDC-3. IN SUMMARY (1) NBCe1 is necessary for normal proximal tubule NaDC-1 expression; (2) NBCe1 deletion results in stimulation of a novel citrate reabsorptive pathway; and (3) NBCe1 is necessary for normal 2-oxoglutarate metabolism through mechanisms independent of expression of known transport and metabolic pathways.
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Affiliation(s)
- Gunars Osis
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Mary E Handlogten
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | | | - Weitao Huang
- Renal Division, Tulane University College of Medicine, New Orleans, Louisiana
| | - Michael F Romero
- Department of Physiology & Biomedical Engineering and Nephrology & Hypertension, Mayo Clinic College Of Medicine, Rochester, Minnesota
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
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Abstract
The impaired capacity of the kidney to excrete sodium plays an essential role in the development of hypertension. Adrenal corticosteroids control renal handling of sodium by regulating tubular sodium reabsorption in the distal nephron where both mineralocorticoid receptors (MR) and glucocorticoid receptors are expressed. In addition, cell type- and segment-specific expression of 11β-HSD2 and sodium transporters such as Na-Cl cotransporter (NCC), epithelial sodium channel (ENaC), and pendrin/Na(+)-driven Cl(-)/HCO3 (-) exchanger (NDCBE) builds a distinctive model of sodium transport in the aldosterone-sensitive distal nephron. Aberrant MR activation in the distal nephron triggers salt-sensitive hypertension and hypokalemia through inappropriate sodium reabsorption and potassium secretion. However, MR activity is not necessarily modulated by the ligand alone. Recently, several lines of evidence revealed alternative mechanisms that regulate the activity of MR in a ligand-independent manner or through ligand binding modulation. This review summarizes the disorders related to MR activation in individual tubular cells and highlights the renal mechanism of salt-sensitive hypertension and new approaches for the prevention and treatment of this disease.
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Affiliation(s)
- Nobuhiro Ayuzawa
- Department of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
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Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
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Atrophic thyroid follicles and inner ear defects reminiscent of cochlear hypothyroidism in Slc26a4-related deafness. Mamm Genome 2014; 25:304-16. [PMID: 24760582 DOI: 10.1007/s00335-014-9515-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 01/10/2023]
Abstract
Thyroid hormone is essential for inner ear development and is required for auditory system maturation. Human mutations in SLC26A4 lead to a syndromic form of deafness with enlargement of the thyroid gland (Pendred syndrome) and non-syndromic deafness (DFNB4). We describe mice with an Slc26a4 mutation, Slc26a4 (loop/loop) , which are profoundly deaf but show a normal sized thyroid gland, mimicking non-syndromic clinical signs. Histological analysis of the thyroid gland revealed defective morphology, with a majority of atrophic microfollicles, while measurable thyroid hormone in blood serum was within the normal range. Characterization of the inner ear showed a spectrum of morphological and molecular defects consistent with inner ear pathology, as seen in hypothyroidism or disrupted thyroid hormone action. The pathological inner ear hallmarks included thicker tectorial membrane with reduced β-tectorin protein expression, the absence of BK channel expression of inner hair cells, and reduced inner ear bone calcification. Our study demonstrates that deafness in Slc26a4 (loop/loop) mice correlates with thyroid pathology, postulating that sub-clinical thyroid morphological defects may be present in some DFNB4 individuals with a normal sized thyroid gland. We propose that insufficient availability of thyroid hormone during inner ear development plays an important role in the mechanism underlying deafness as a result of SLC26A4 mutations.
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Severs D, Hoorn EJ, Rookmaaker MB. A critical appraisal of intravenous fluids: from the physiological basis to clinical evidence. Nephrol Dial Transplant 2014; 30:178-87. [DOI: 10.1093/ndt/gfu005] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Rozenfeld J, Tal O, Kladnitsky O, Adler L, Efrati E, Carrithers SL, Alper SL, Zelikovic I. Pendrin, a novel transcriptional target of the uroguanylin system. Cell Physiol Biochem 2013; 32:221-37. [PMID: 24429828 DOI: 10.1159/000356641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2013] [Indexed: 12/22/2022] Open
Abstract
Guanylin (GN) and uroguanylin (UGN) are low-molecular-weight peptide hormones produced mainly in the intestinal mucosa in response to oral salt load. GN and UGN (guanylin peptides) induce secretion of electrolytes and water in both intestine and kidney. Thought to act as "intestinal natriuretic factors", GN and UGN modulate renal salt secretion by both endocrine mechanisms (linking the digestive system and kidney) and paracrine/autocrine (intrarenal) mechanisms. The cellular function of GN and UGN in intestine and proximal tubule is mediated by guanylyl cyclase C (GC-C)-, cGMP-, and G protein-dependent pathways, whereas, in principal cells of the cortical collecting duct (CCD), these peptide hormones act via GC-C-independent signaling through phospholipase A2 (PLA2). The Cl(-)/HCO(-)3 exchanger pendrin (SLC26A4), encoded by the PDS gene, is expressed in non-α intercalated cells of the CCD. Pendrin is essential for CCD bicarbonate secretion and is also involved in NaCl balance and blood pressure regulation. Our recent studies have provided evidence that pendrin-mediated anion exchange in the CCD is regulated at the transcriptional level by UGN. UGN exerts an inhibitory effect on the pendrin gene promoter likely via heat shock factor 1 (HSF1) action at a defined heat shock element (HSE) site. Recent studies have unraveled novel roles for guanylin peptides in several organ systems including involvement in appetite regulation, olfactory function, cell proliferation and differentiation, inflammation, and reproductive function. Both the guanylin system and pendrin have also been implicated in airway function. Future molecular research into the receptors and signal transduction pathways involved in the action of guanylin peptides and the pendrin anion exchanger in the kidney and other organs, and into the links between them, may facilitate discovery of new therapies for hypertension, heart failure, hepatic failure and other fluid retention syndromes, as well as for diverse diseases such as obesity, asthma, and cancer.
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Affiliation(s)
- Julia Rozenfeld
- Laboratory of Developmental Nephrology, Department of Physiology and Biophysics, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Shibata S, Rinehart J, Zhang J, Moeckel G, Castañeda-Bueno M, Stiegler AL, Boggon TJ, Gamba G, Lifton RP. Mineralocorticoid receptor phosphorylation regulates ligand binding and renal response to volume depletion and hyperkalemia. Cell Metab 2013; 18:660-71. [PMID: 24206662 PMCID: PMC3909709 DOI: 10.1016/j.cmet.2013.10.005] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 07/29/2013] [Accepted: 09/16/2013] [Indexed: 12/30/2022]
Abstract
Nuclear receptors are transcription factors that regulate diverse cellular processes. In canonical activation, ligand availability is sufficient to produce receptor binding, entraining downstream signaling. The mineralocorticoid receptor (MR) is normally activated by aldosterone, which is produced in both volume depletion and hyperkalemia, states that require different homeostatic responses. We report phosphorylation at S843 in the MR ligand-binding domain that prevents ligand binding and activation. In kidney, MR(S843-P) is found exclusively in intercalated cells of the distal nephron. In volume depletion, angiotensin II and WNK4 signaling decrease MR(S843-P) levels, whereas hyperkalemia increases MR(S843-P). Dephosphorylation of MR(S843-P) results in aldosterone-dependent increases of the intercalated cell apical proton pump and Cl(-)/HCO3(-) exchangers, increasing Cl(-) reabsorption and promoting increased plasma volume while inhibiting K(+) secretion. These findings reveal a mechanism regulating nuclear hormone receptor activity and implicate selective MR activation in intercalated cells in the distinct adaptive responses to volume depletion and hyperkalemia.
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Affiliation(s)
- Shigeru Shibata
- Department of Genetics and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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28
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Petrenko AG, Zozulya SA, Deyev IE, Eladari D. Insulin receptor-related receptor as an extracellular pH sensor involved in the regulation of acid–base balance. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2170-5. [DOI: 10.1016/j.bbapap.2012.11.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/16/2012] [Accepted: 11/19/2012] [Indexed: 12/25/2022]
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Mohebbi N, Perna A, van der Wijst J, Becker HM, Capasso G, Wagner CA. Regulation of two renal chloride transporters, AE1 and pendrin, by electrolytes and aldosterone. PLoS One 2013; 8:e55286. [PMID: 23383138 PMCID: PMC3561381 DOI: 10.1371/journal.pone.0055286] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2012] [Accepted: 12/21/2012] [Indexed: 01/14/2023] Open
Abstract
The renal handling of salt and protons and bicarbonate are intricately linked through shared transport mechanisms for sodium, chloride, protons, and bicarbonate. In the collecting duct, the regulated fine-tuning of salt and acid-base homeostasis is achieved by a series of transport proteins located in different cell types, intercalated and principal cells. Intercalated cells are considered to be of less importance for salt handling but recent evidence has suggested that the anion exchanger pendrin may participate in salt reabsorption and blood pressure regulation. Here, we examined the regulated expression of two functionally related but differentially expressed anion exchangers, AE1 and pendrin, by dietary electrolyte intake and aldosterone. Cortical expression of pendrin was regulated on mRNA and protein level. The combination of NaHCO3 and DOCA enhanced pendrin mRNA and protein levels, whereas DOCA or NaHCO3 alone had no effect. NaCl or KHCO3 increased pendrin mRNA, KCl decreased its mRNA abundance. On protein level, NH4Cl, NaCl, and KCl reduced pendrin expression, the other treatments were without effect. In contrast, AE1 mRNA or protein expression in kidney cortex was regulated by none of these treatments. In kidney medulla, NaHCO3/DOCA or NaHCO3 alone enhanced AE1 mRNA levels. AE1 protein abundance was increased by NH4Cl, NaHCO3/DOCA, and NaCl. Immunolocalization showed that during NH4Cl treatment the relative number of AE1 positive cells was increased and pendrin expressing cells reduced. Thus, pendrin and AE1 are differentially regulated with distinct mechanisms that separately affect mRNA and protein levels. Pendrin is regulated by acidosis and chloride intake, whereas AE1 is enhanced by acidosis, NaCl, and the combination of DOCA and NaHCO3.
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Affiliation(s)
- Nilufar Mohebbi
- Institute of Physiology and Zurich Center for Integrative Human Physiology-ZIHP, Zurich, Switzerland
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Cornelius RJ, Wen D, Hatcher LI, Sansom SC. Bicarbonate promotes BK-α/β4-mediated K excretion in the renal distal nephron. Am J Physiol Renal Physiol 2012; 303:F1563-71. [PMID: 22993067 DOI: 10.1152/ajprenal.00490.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ca-activated K channels (BK), which are stimulated by high distal nephron flow, are utilized during high-K conditions to remove excess K. Because BK predominantly reside with BK-β4 in acid/base-transporting intercalated cells (IC), we determined whether BK-β4 knockout mice (β4KO) exhibit deficient K excretion when consuming a high-K alkaline diet (HK-alk) vs. high-K chloride diet (HK-Cl). When wild type (WT) were placed on HK-alk, but not HK-Cl, renal BK-β4 expression increased (Western blot). When WT and β4KO were placed on HK-Cl, plasma K concentration ([K]) was elevated compared with control K diets; however, K excretion was not different between WT and β4KO. When HK-alk was consumed, the plasma [K] was lower and K clearance was greater in WT compared with β4KO. The urine was alkaline in mice on HK-alk; however, urinary pH was not different between WT and β4KO. Immunohistochemical analysis of pendrin and V-ATPase revealed the same increases in β-IC, comparing WT and β4KO on HK-alk. We found an amiloride-sensitive reduction in Na excretion in β4KO, compared with WT, on HK-alk, indicating enhanced Na reabsorption as a compensatory mechanism to secrete K. Treating mice with an alkaline, Na-deficient, high-K diet (LNaHK) to minimize Na reabsorption exaggerated the defective K handling of β4KO. When WT on LNaHK were given NH(4)Cl in the drinking water, K excretion was reduced to the magnitude of β4KO on LNaHK. These results show that WT, but not β4KO, efficiently excretes K on HK-alk but not on HK-Cl and suggest that BK-α/β4-mediated K secretion is promoted by bicarbonaturia.
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Affiliation(s)
- Ryan J Cornelius
- Dept. of Cellular and Integrative Physiology, Nebraska Medical Center, Omaha, NE 68198-5850, USA
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31
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Berend K, van Hulsteijn LH, Gans ROB. Chloride: the queen of electrolytes? Eur J Intern Med 2012; 23:203-11. [PMID: 22385875 DOI: 10.1016/j.ejim.2011.11.013] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 10/20/2011] [Accepted: 11/22/2011] [Indexed: 12/26/2022]
Abstract
BACKGROUND Channelopathies, defined as diseases that are caused by mutations in genes encoding ion channels, are associated with a wide variety of symptoms and have been documented extensively over the past decade. In contrast, despite the important role of chloride in serum, textbooks in general do not allocate chapters exclusively on hypochloremia or hyperchloremia and information on chloride other than channelopathies is scattered in the literature. STUDY DESIGN To systematically review the function of chloride in man, data for this review include searches of MEDLINE, PubMed, and references from relevant articles including the search terms "chloride," "HCl," "chloride channel" "acid-base," "acidosis," "alkalosis," "anion gap" "strong anion gap" "Stewart," "base excess" and "lactate." In addition, internal medicine, critical care, nephrology and gastroenterology textbooks were evaluated on topics pertaining the assessment and management of acid-base disorders, including reference lists from journals or textbooks. CONCLUSION Chloride is, after sodium, the most abundant electrolyte in serum, with a key role in the regulation of body fluids, electrolyte balance, the preservation of electrical neutrality, acid-base status and it is an essential component for the assessment of many pathological conditions. When assessing serum electrolytes, abnormal chloride levels alone usually signify a more serious underlying metabolic disorder, such as metabolic acidosis or alkalosis. Chloride is an important component of diagnostic tests in a wide array of clinical situations. In these cases, chloride can be tested in sweat, serum, urine and feces. Abnormalities in chloride channel expression and function in many organs can cause a range of disorders.
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Affiliation(s)
- Kenrick Berend
- Nephrology department, St. Elisabeth Hospital, Willemstad, Curaçao, The Netherlands.
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32
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Luke RG, Galla JH. It is chloride depletion alkalosis, not contraction alkalosis. J Am Soc Nephrol 2012; 23:204-7. [PMID: 22223876 DOI: 10.1681/asn.2011070720] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Maintenance of metabolic alkalosis generated by chloride depletion is often attributed to volume contraction. In balance and clearance studies in rats and humans, we showed that chloride repletion in the face of persisting alkali loading, volume contraction, and potassium and sodium depletion completely corrects alkalosis by a renal mechanism. Nephron segment studies strongly suggest the corrective response is orchestrated in the collecting duct, which has several transporters integral to acid-base regulation, the most important of which is pendrin, a luminal Cl/HCO(3)(-) exchanger. Chloride depletion alkalosis should replace the notion of contraction alkalosis.
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Affiliation(s)
- Robert G Luke
- Department of Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
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Rozenfeld J, Tal O, Kladnitsky O, Adler L, Efrati E, Carrithers SL, Alper SL, Zelikovic I. The pendrin anion exchanger gene is transcriptionally regulated by uroguanylin: a novel enterorenal link. Am J Physiol Renal Physiol 2011; 302:F614-24. [PMID: 22129966 DOI: 10.1152/ajprenal.00189.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pendrin/SLC26A4 Cl(-)/HCO(3)(-) exchanger, encoded by the PDS gene, is expressed in cortical collecting duct (CCD) non-A intercalated cells. Pendrin is essential for CCD bicarbonate secretion and is also involved in NaCl balance and blood pressure regulation. The intestinal peptide uroguanylin (UGN) is produced in response to oral salt load and can function as an "intestinal natriuretic hormone." We aimed to investigate whether UGN modulates pendrin activity and to explore the molecular mechanisms responsible for this modulation. Injection of UGN into mice resulted in decreased pendrin mRNA and protein expression in the kidney. UGN decreased endogenous pendrin mRNA levels in HEK293 cells. A 4.2-kb human PDS (hPDS) promoter sequence and consecutive 5' deletion products were cloned into luciferase reporter vectors and transiently transfected into HEK293 cells. Exposure of transfected cells to UGN decreased hPDS promoter activity. This UGN-induced effect on the hPDS promoter occurred within a 52-bp region encompassing a single heat shock element (HSE). The effect of UGN on the promoter was abolished when the HSE located between nt -1119 and -1115 was absent or was mutated. Furthermore, treatment of HEK293 cells with heat shock factor 1 (HSF1) small interfering RNA (siRNA) reversed the UGN-induced decrease in endogenous PDS mRNA level. In conclusion, pendrin-mediated Cl(-)/HCO(3)(-) exchange in the renal tubule may be regulated transcriptionally by the peptide hormone UGN. UGN exerts its inhibitory activity on the hPDS promoter likely via HSF1 action at a defined HSE site. These data define a novel signaling pathway involved in the enterorenal axis controlling electrolyte and water homeostasis.
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Affiliation(s)
- Julia Rozenfeld
- Laboratory of Developmental Nephrology, Department of Physiology and Biophysics, Haifa, Israel
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34
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Dossena S, Nofziger C, Tamma G, Bernardinelli E, Vanoni S, Nowak C, Grabmayer E, Kössler S, Stephan S, Patsch W, Paulmichl M. Molecular and functional characterization of human pendrin and its allelic variants. Cell Physiol Biochem 2011; 28:451-66. [PMID: 22116358 DOI: 10.1159/000335107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2011] [Indexed: 12/13/2022] Open
Abstract
Pendrin (SLC26A4, PDS) is an electroneutral anion exchanger transporting I(-), Cl(-), HCO(3)(-), OH(-), SCN(-) and formate. In the thyroid, pendrin is expressed at the apical membrane of the follicular epithelium and may be involved in mediating apical iodide efflux into the follicle; in the inner ear, it plays a crucial role in the conditioning of the pH and ion composition of the endolymph; in the kidney, it may exert a role in pH homeostasis and regulation of blood pressure. Mutations of the pendrin gene can lead to syndromic and non-syndromic hearing loss with EVA (enlarged vestibular aqueduct). Functional tests of mutated pendrin allelic variants found in patients with Pendred syndrome or non-syndromic EVA (ns-EVA) revealed that the pathological phenotype is due to the reduction or loss of function of the ion transport activity. The diagnosis of Pendred syndrome and ns-EVA can be difficult because of the presence of phenocopies of Pendred syndrome and benign polymorphisms occurring in the general population. As a consequence, defining whether or not an allelic variant is pathogenic is crucial. Recently, we found that the two parameters used so far to assess the pathogenic potential of a mutation, i.e. low incidence in the control population, and substitution of evolutionary conserved amino acids, are not always reliable for predicting the functionality of pendrin allelic variants; actually, we identified mutations occurring with the same frequency in the cohort of hearing impaired patients and in the control group of normal hearing individuals. Moreover, we identified functional polymorphisms affecting highly conserved amino acids. As a general rule however, we observed a complete loss of function for all truncations and amino acid substitutions involving a proline. In this view, clinical and radiological studies should be combined with genetic and molecular studies for a definitive diagnosis. In performing genetic studies, the possibility that the mutation could affect regions other than the pendrin coding region, such as its promoter region and/or the coding regions of functionally related genes (FOXI1, KCNJ10), should be taken into account. The presence of benign polymorphisms in the population suggests that genetic studies should be corroborated by functional studies; in this context, the existence of hypo-functional variants and possible differences between the I(-)/Cl(-) and Cl(-)/HCO(3)(-) exchange activities should be carefully evaluated.
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Affiliation(s)
- Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria.
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35
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Wagner CA, Mohebbi N, Capasso G, Geibel JP. The anion exchanger pendrin (SLC26A4) and renal acid-base homeostasis. Cell Physiol Biochem 2011; 28:497-504. [PMID: 22116363 DOI: 10.1159/000335111] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2011] [Indexed: 01/29/2023] Open
Abstract
The anion exchanger pendrin (Pds, SLC26A4) transports various anions including bicarbonate, chloride and iodide. In the kidney, pendrin is exclusively expressed on the luminal pole of bicarbonate-secretory type B intercalated cells. Genetic ablation of pendrin in mice abolishes luminal chloride-bicarbonate exchanger activity from type B intercalated cells suggesting that pendrin is the apical bicarbonate extruding pathway. The renal expression of pendrin is developmentally adapted and pendrin positive cells originate from both the uretric bud and mesenchyme. In adult kidney, pendrin expression and activity is regulated by systemic acid-base status, dietary electrolyte intake (mostly chloride), and hormones such as angiotensin II and aldosterone which can affect subcellular localization, the relative number of pendrin expressing cells, and the overall abundance consistent with a role of pendrin in maintaining normal acid-base homeostasis. This review summarizes recent findings on the role and regulation of pendrin in the context of the kidneys role in acid-base homeostasis in health and disease.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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36
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Rozenfeld J, Efrati E, Adler L, Tal O, Carrithers SL, Alper SL, Zelikovic I. Transcriptional regulation of the pendrin gene. Cell Physiol Biochem 2011; 28:385-96. [PMID: 22116353 DOI: 10.1159/000335100] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2011] [Indexed: 12/20/2022] Open
Abstract
Pendrin (SLC26A4), a Cl(-)/anion exchanger encoded by the gene PDS, is highly expressed in the kidney, thyroid and inner ear epithelia and is essential for bicarbonate secretion/chloride reabsorption, iodide accumulation and endolymph ion balance, respectively. The molecular mechanisms controlling pendrin activity in renal, thyroid and inner ear epithelia have been the subject of recent studies. The effects of ambient pH, the hormone aldosterone and the peptide uroguanylin (UGN; the "intestinal natriuretic hormone"), known modulators of electrolyte balance, on transcription of the pendrin gene, have been investigated. Luciferase reporter plasmids containing different length fragments of the human PDS (hPDS) promoter were transfected into renal HEK293, thyroid LA2, and inner ear VOT36 epithelial cells. Acidic pH decreased and alkaline pH increased hPDS promoter activity in transfected HEK293 and VOT36, but not in LA2 cells. Aldosterone reduced hPDS promoter activity in HEK293 but had no effect in LA2 and VOT36 cells. These pH and aldosterone-induced effects on the hPDS promoter occurred within 96-bp and 89-bp regions, respectively, which likely contain distinct response elements to these modulators. Injection of UGN into mice resulted in decreased pendrin mRNA and protein expression in the kidney. Exposure of transfected HEK293 to UGN decreased hPDS promoter activity. The findings provided evidence for the presence of a UGN response element within the 96-bp region overlapping with the pH response element on the hPDS promoter. Pendrin is also expressed in airway epithelium. The cytokins interleukin 4 (IL-4) and interleukin-13 (IL-13), known regulators of airway surface function, have been shown to increase hPDS promoter activity by a STAT6-dependent mechanism. In conclusion, systemic pH, the hormone aldosterone, and the peptide UGN influence renal tubular pendrin gene expression and, perhaps, pendrin-mediated Cl(-)/HCO(3)(-) exchange at the transcriptional level. Pendrin-driven anion transport in the endolymph and at the airway surface may be regulated transcriptionally by systemic pH and IL-3/IL-4, respectively. The distinct response elements and the corresponding transcription factors mediating the effect of these modulators on the PDS promoter remain to be identified and characterized.
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Affiliation(s)
- Julia Rozenfeld
- Laboratory of Developmental Nephrology, Department of Physiology and Biophysics, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Barone S, Amlal H, Xu J, Soleimani M. Deletion of the Cl-/HCO3- exchanger pendrin downregulates calcium-absorbing proteins in the kidney and causes calcium wasting. Nephrol Dial Transplant 2011; 27:1368-79. [PMID: 21873623 DOI: 10.1093/ndt/gfr505] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The epithelial calcium channel (ECaC) (TRPV5) and the Cl-/HCO3- exchanger pendrin (SLC26A4) are expressed on the apical membrane of tubular cells in the distal nephron and play essential roles in calcium re-absorption and bicarbonate secretion, respectively, in the kidney. METHODS A combination of functional and molecular biology techniques were employed to examine the role of pendrin deletion in calcium excretion. RESULTS Here, we demonstrate that deletion of pendrin causes acidic urine [urine pH 4.9 in knockout (KO) versus 5.9 in wild-type (WT) mice, P<0.03)] and downregulates the calcium-absorbing molecules ECaC and Na/Ca exchanger in the kidney, as shown by northern hybridization, immunoblot analysis and/or immunofluorescent labeling. These changes were associated with a ∼100% increase in 24-h urine calcium excretion in pendrin null mice. Subjecting the pendrin WT and KO mice to oral bicarbonate loading for 12 days increased the urine pH to ∼8 in both genotypes, normalized the expression of ECaC and Na/Ca exchanger and reduced the urine calcium excretion in pendrin-null mice to levels comparable to WT mice. CONCLUSIONS We suggest that pendrin dysfunction should be suspected and investigated in humans with an otherwise unexplained acidic urine and hypercalciuria.
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Affiliation(s)
- Sharon Barone
- Research Services, Veterans Administration Medical Center, Cincinnati, OH, USA
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Schwartz JH, Alexander EA. Adaptation of intercalated cells along the collecting duct to systemic acid/base changes. Kidney Int 2011; 78:949-51. [PMID: 21030969 DOI: 10.1038/ki.2010.343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Collecting duct intercalated cells respond to short-term acid/base perturbations by rapidly shuttling H(+)-ATPase to and from the plasma membrane. Purkerson et al. provide information on the regulation of the anion transporters during chronic acidosis and acute recovery (alkalosis). They found that the major mechanism for both acute and chronic states is regulation of both the H(+)-ATPase and the anion exchangers plus changes in the overall expression level of these anion transporters in chronic adaptation.
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Affiliation(s)
- John H Schwartz
- Renal Section, Boston University Medical Center and Boston University School of Medicine, Boston, Massachusetts, USA.
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Almomani EY, Chu CY, Cordat E. Mis-trafficking of bicarbonate transporters: implications to human diseasesThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process. Biochem Cell Biol 2011; 89:157-77. [DOI: 10.1139/o10-153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bicarbonate is a waste product of mitochondrial respiration and one of the main buffers in the human body. Thus, bicarbonate transporters play an essential role in maintaining acid-base balance but also during fetal development as they ensure tight regulation of cytosolic and extracellular environments. Bicarbonate transporters belong to two gene families, SLC4A and SLC26A. Proteins from these two families are widely expressed, and thus mutations in their genes result in various diseases that affect bones, pancreas, reproduction, brain, kidneys, eyes, heart, thyroid, red blood cells, and lungs. In this minireview, we discuss the current state of knowledge regarding the effect of SLC4A and SLC26A mutants, with a special emphasis on mutants that have been studied in mammalian cell lines and how they correlate with phenotypes observed in mice models.
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Affiliation(s)
- Ensaf Y. Almomani
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Carmen Y.S. Chu
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Izumi Y, Hori K, Nakayama Y, Kimura M, Hasuike Y, Nanami M, Kohda Y, Otaki Y, Kuragano T, Obinata M, Kawahara K, Tanoue A, Tomita K, Nakanishi T, Nonoguchi H. Aldosterone requires vasopressin V1a receptors on intercalated cells to mediate acid-base homeostasis. J Am Soc Nephrol 2011; 22:673-80. [PMID: 21415155 DOI: 10.1681/asn.2010050468] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Both aldosterone and luminal vasopressin may contribute to the maintenance of acid-base homeostasis, but the functional relationship between these hormones is not well understood. The effects of luminal vasopressin likely result from its interaction with V1a receptors on the luminal membranes of intercalated cells in the collecting duct. Here, we found that mice lacking the V1a receptor exhibit type 4 renal tubular acidosis. The administration of the mineralocorticoid agonist fludrocortisone ameliorated the acidosis by restoring excretion of urinary ammonium via increased expression of Rhcg and H-K-ATPase and decreased expression of H-ATPase. In a cell line of intercalated cells established from transgenic rats expressing the mineralocorticoid and V1a receptors, but not V2 receptors, knockdown of the V1a receptor gene abrogated the effects of aldosterone on H-K-ATPase, Rhcg, and H-ATPase expression. These data suggest that defects in the vasopressin V1a receptor in intercalated cells can cause type 4 renal tubular acidosis and that the tubular effects of aldosterone depend on a functional V1a receptor in the intercalated cells.
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Affiliation(s)
- Yuichiro Izumi
- Department of Nephrology, Graduate School of Faculty of Life Science, Kumamoto University, Kumamoto, Japan
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Amlal H, Soleimani M. Pendrin as a Novel Target for Diuretic Therapy. Cell Physiol Biochem 2011; 28:521-6. [DOI: 10.1159/000335117] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2011] [Indexed: 01/04/2023] Open
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Pech V, Pham TD, Hong S, Weinstein AM, Spencer KB, Duke BJ, Walp E, Kim YH, Sutliff RL, Bao HF, Eaton DC, Wall SM. Pendrin modulates ENaC function by changing luminal HCO3-. J Am Soc Nephrol 2010; 21:1928-41. [PMID: 20966128 DOI: 10.1681/asn.2009121257] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The epithelial Na(+) channel, ENaC, and the Cl(-)/HCO(3)(-) exchanger, pendrin, mediate NaCl absorption within the cortical collecting duct and the connecting tubule. Although pendrin and ENaC localize to different cell types, ENaC subunit abundance and activity are lower in aldosterone-treated pendrin-null mice relative to wild-type mice. Because pendrin mediates HCO(3)(-) secretion, we asked if increasing distal delivery of HCO(3)(-) through a pendrin-independent mechanism "rescues" ENaC function in pendrin-null mice. We gave aldosterone and NaHCO(3) to increase pendrin-dependent HCO(3)(-) secretion within the connecting tubule and cortical collecting duct, or gave aldosterone and NaHCO(3) plus acetazolamide to increase luminal HCO(3)(-) concentration, [HCO(3)(-)], independent of pendrin. Following treatment with aldosterone and NaHCO(3), pendrin-null mice had lower urinary pH and [HCO(3)(-)] as well as lower renal ENaC abundance and function than wild-type mice. With the addition of acetazolamide, however, acid-base balance as well as ENaC subunit abundance and function was similar in pendrin-null and wild-type mice. We explored whether [HCO(3)(-)] directly alters ENaC abundance and function in cultured mouse principal cells (mpkCCD). Amiloride-sensitive current and ENaC abundance rose with increased [HCO(3)(-)] on the apical or the basolateral side, independent of the substituting anion. However, ENaC was more sensitive to changes in [HCO(3)(-)] on the basolateral side of the monolayer. Moreover, increasing [HCO(3)(-)] on the apical and basolateral side of Xenopus kidney cells increased both ENaC channel density and channel activity. We conclude that pendrin modulates ENaC abundance and function, at least in part by increasing luminal [HCO(3)(-)] and/or pH.
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Affiliation(s)
- Vladimir Pech
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
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Adaptation to metabolic acidosis and its recovery are associated with changes in anion exchanger distribution and expression in the cortical collecting duct. Kidney Int 2010; 78:993-1005. [PMID: 20592712 DOI: 10.1038/ki.2010.195] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
It is well known that acid/base disturbances modulate proton/bicarbonate transport in the cortical collecting duct. To study the adaptation further we measured the effect of three days of acidosis followed by the rapid recovery from this acidosis on the number and type of intercalated cells in the rabbit cortical collecting duct. Immunofluorescence was used to determine the expression of apical pendrin in β-intercalated cells and the basolateral anion exchanger (AE1) in α-intercalated cells. Acidosis resulted in decreased bicarbonate and increased proton secretion, which correlated with reduced pendrin expression and the number of pendrin-positive cells, as well as decreased pendrin mRNA and protein abundance in this nephron segment. There was a concomitant increase of basolateral AE1 and α-cell number. Intercalated cell proliferation did not seem to play a role in the adaptation to acidosis. Alkali loading for 6-20 h after acidosis doubled the bicarbonate secretory flux and reduced proton secretion. Pendrin and AE1 expression patterns returned to control levels, demonstrating that adaptive changes by intercalated cells are rapidly reversible. Thus, regulation of intercalated cell anion exchanger expression and distribution plays a key role in adaptation of the cortical collecting duct to perturbations of acid/base.
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Dror AA, Politi Y, Shahin H, Lenz DR, Dossena S, Nofziger C, Fuchs H, Hrabé de Angelis M, Paulmichl M, Weiner S, Avraham KB. Calcium oxalate stone formation in the inner ear as a result of an Slc26a4 mutation. J Biol Chem 2010; 285:21724-35. [PMID: 20442411 DOI: 10.1074/jbc.m110.120188] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium oxalate stone formation occurs under pathological conditions and accounts for more than 80% of all types of kidney stones. In the current study, we show for the first time that calcium oxalate stones are formed in the mouse inner ear of a genetic model for hearing loss and vestibular dysfunction in humans. The vestibular system within the inner ear is dependent on extracellular tiny calcium carbonate minerals for proper function. Thousands of these biominerals, known as otoconia, are associated with the utricle and saccule sensory maculae and are vital for mechanical stimulation of the sensory hair cells. We show that a missense mutation within the Slc26a4 gene abolishes the transport activity of its encoded protein, pendrin. As a consequence, dramatic changes in mineral composition, size, and shape occur within the utricle and saccule in a differential manner. Although abnormal giant carbonate minerals reside in the utricle at all ages, in the saccule, a gradual change in mineral composition leads to a formation of calcium oxalate in adult mice. By combining imaging and spectroscopy tools, we determined the profile of mineral composition and morphology at different time points. We propose a novel mechanism for the accumulation and aggregation of oxalate crystals in the inner ear.
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Affiliation(s)
- Amiel A Dror
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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Nowik M, Kampik NB, Mihailova M, Eladari D, Wagner CA. Induction of Metabolic Acidosis with Ammonium Chloride (NH 4Cl) in Mice and Rats – Species Differences and Technical Considerations. Cell Physiol Biochem 2010; 26:1059-72. [DOI: 10.1159/000323984] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2010] [Indexed: 11/19/2022] Open
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Vázquez AGM, Montesinos IG, Jiménez AM, García JAR, García JG, Hernández JA. [Pendred's syndrome: a cause of goiter associated with deafness]. ACTA ACUST UNITED AC 2009; 56:428-30. [PMID: 19959154 DOI: 10.1016/s1575-0922(09)72714-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Accepted: 09/07/2009] [Indexed: 11/28/2022]
Abstract
Pendred's syndrome is an autosomal recessive disorder leading to congenital sensorineural hearing loss and a variable degree of goiter due to reduced iodine organification. The cause of this disease is dysfunction of an anion transporter protein located on the apical membrane of thyrocytes, called pendrin, which is also found in the kidney and cochlea. Molecular analysis of the gene is useful to identify other affected family members and provide proper genetic advice and early diagnosis in descendants. We present the cases of two siblings with sensorineural deafness who were diagnosed with Pendred's syndrome as adults because one of them consulted for goiter.
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Wang G, Ring T, Li C, Kim SW, Wen J, Djurhuus JC, Nielsen S, Frøkiaer J. Unilateral ureteral obstruction alters expression of acid-base transporters in rat kidney. J Urol 2009; 182:2964-73. [PMID: 19846141 DOI: 10.1016/j.juro.2009.08.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Indexed: 11/28/2022]
Abstract
PURPOSE Unilateral ureteral obstruction is a common clinical problem that is often associated with a urinary acidification defect caused by decreased net H(+) secretion and/or HCO(3)(-) reabsorption. To clarify the molecular mechanisms of these defects we examined expression levels of key acid-base transporters along the renal nephron segments and collecting duct. MATERIALS AND METHODS Wistar rats (Møllegard Breeding Centre, Eiby, Denmark) underwent 24-hour unilateral ureteral obstruction, unilateral ureteral obstruction release followed for 4 days or unilateral ureteral obstruction release followed for 4 days plus experimental acidosis induced by NH(4)Cl oral administration. After sacrifice kidneys were processed for immunoblotting and immunohistochemistry. RESULTS Semiquantitative immunoblotting revealed that unilateral ureteral obstruction caused significant mean +/- SE down-regulation of type 3 Na(+)/H(+) exchanger to 53% +/- 9%, electrogenic Na(+)/HCO(3)(-) cotransporter to 60% +/- 9%, type 1 bumetanide sensitive Na(+)-K(+)(NH(4)(+)) -2Cl(-) cotransporter to 64% +/- 7%, electroneutral Na(+)/HCO(3)(-) cotransporter to 43% +/- 4% and anion exchanger (pendrin) to 53% +/- 10% in the obstructed kidney, which was confirmed by immunohistochemistry. After release of unilateral ureteral obstruction down-regulation of these transporters persisted together with marked down-regulation of H(+)-adenosine triphosphatase in the obstructed kidney. In rats with unilateral ureteral obstruction release followed for 4 days with experimental acidosis induced by NH(4)Cl oral administration plasma pH and HCO(3)(-) were dramatically decreased in response to NH(4)Cl for 2 days compared with those in sham operated rats with acid loading, indicating a defect in H(+) excretion and HCO(3)(-) reabsorption after obstruction release. Expression of these transporters did not change in the contralateral nonobstructed kidney of rats with unilateral ureteral obstruction and unilateral ureteral obstruction release followed for 4 days. CONCLUSIONS The expression of renal acid-base transporters is markedly decreased in the obstructed kidney, which may be responsible for the contribution of impaired renal H(+) excretion and HCO(3)(-) reabsorption to the urinary acidification defect in response to unilateral ureteral obstruction.
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Affiliation(s)
- Guixian Wang
- Water and Salt Research Center, University of Aarhus, Aarhus, Denmark
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Wang G, Topcu SO, Ring T, Wen J, Djurhuus JC, Kwon TH, Nielsen S, Frøkiaer J. Age-dependent renal expression of acid-base transporters in neonatal ureter obstruction. Pediatr Nephrol 2009; 24:1487-500. [PMID: 19495807 DOI: 10.1007/s00467-009-1193-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 03/12/2009] [Accepted: 03/27/2009] [Indexed: 12/22/2022]
Abstract
Congenital obstructive nephropathy accounts for a major proportion of renal insufficiency in infancy and childhood. In an earlier investigation we demonstrated that bilateral complete ureteral obstruction (BUO) in rats is associated with inadequate urinary acidification [Am J Physiol Renal Physiol. 295(2):F497-506, 2008]. The aim of the study reported here was to determine whether this defect is also associated with unilateral ureteral obstruction (UUO), which is clinically more common than BUO. The time-course of the changes in protein expression levels of major renal acid-base transporters was examined at 7 and 14 weeks in rats with neonatally induced partial unilateral ureteral obstruction (PUUO), which was performed within the first 48 h of life. We observed that protein expression of the renal acid-base transporters NHE3, NBC1, NBCn1, pendrin and Na(+)-K(+)-ATPase was increased in both obstructed and non-obstructed kidneys 7 weeks after the induction of neonatal PUUO. This was confirmed by immunocytochemistry. In contrast, 14 weeks after the induction of PUUO, there was a significant downregulation of the renal acid-base transporters NBC1, NBCn1 and Na(+)-K(+)-ATPase in the obstructed kidneys. These time/age-dependent changes in protein expression were associated with parallel changes in renal function resulting in urine acidification in response to exogenous acid loading. In conclusion, these results show that downregulation of protein expression is a time/age-dependent response to PUUO, which could contribute to the decreased net acid excretion and development of metabolic acidosis in neonatal rats with PUUO.
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Affiliation(s)
- Guixian Wang
- The Water and Salt Research Center, University of Aarhus, Aarhus C, Denmark
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Kim YH, Pham TD, Zheng W, Hong S, Baylis C, Pech V, Beierwaltes WH, Farley DB, Braverman LE, Verlander JW, Wall SM. Role of pendrin in iodide balance: going with the flow. Am J Physiol Renal Physiol 2009; 297:F1069-79. [PMID: 19605545 DOI: 10.1152/ajprenal.90581.2008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Pendrin is expressed in the apical regions of type B and non-A, non-B intercalated cells, where it mediates Cl(-) absorption and HCO3(-) secretion through apical Cl(-)/HCO3(-) exchange. Since pendrin is a robust I(-) transporter, we asked whether pendrin is upregulated with dietary I(-) restriction and whether it modulates I(-) balance. Thus I(-) balance was determined in pendrin null and in wild-type mice. Pendrin abundance was evaluated with immunoblots, immunohistochemistry, and immunogold cytochemistry with morphometric analysis. While pendrin abundance was unchanged when dietary I(-) intake was varied over the physiological range, I(-) balance differed in pendrin null and in wild-type mice. Serum I(-) was lower, while I(-) excretion was higher in pendrin null relative to wild-type mice, consistent with a role of pendrin in renal I(-) absorption. Increased H2O intake enhanced differences between wild-type and pendrin null mice in I(-) balance, suggesting that H2O intake modulates pendrin abundance. Raising water intake from approximately 4 to approximately 11 ml/day increased the ratio of B cell apical plasma membrane to cytoplasm pendrin label by 75%, although circulating renin, aldosterone, and serum osmolality were unchanged. Further studies asked whether H2O intake modulates pendrin through the action of AVP. We observed that H2O intake modulated pendrin abundance even when circulating vasopressin levels were clamped. We conclude that H2O intake modulates pendrin abundance, although not likely through a direct, type 2 vasopressin receptor-dependent mechanism. As water intake rises, pendrin becomes increasingly critical in the maintenance of Cl(-) and I(-) balance.
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Affiliation(s)
- Young Hee Kim
- Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
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