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Gamba G. From Fish Physiology to Human Disease: The Discovery of the NCC, NKCC2, and the Cation-Coupled Chloride Cotransporters. Kidney360 2024; 5:133-141. [PMID: 37968800 PMCID: PMC10833596 DOI: 10.34067/kid.0000000000000307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/26/2023] [Indexed: 11/17/2023]
Abstract
The renal Na-K-2Cl and Na-Cl cotransporters are the major salt reabsorption pathways in the thick ascending limb of Henle loop and the distal convoluted tubule, respectively. These transporters are the target of the loop and thiazide type diuretics extensively used in the world for the treatment of edematous states and arterial hypertension. The diuretics appeared in the market many years before the salt transport systems were discovered. The evolving of the knowledge and the cloning of the genes encoding the Na-K-2Cl and Na-Cl cotransporters were possible thanks to the study of marine species. This work presents the history of how we came to know the mechanisms for the loop and thiazide type diuretics actions, the use of marine species in the cloning process of these cotransporters and therefore in the whole solute carrier cotransproters 12 (SLC12) family of electroneutral cation chloride cotransporters, and the disease associated with each member of the family.
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Affiliation(s)
- Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico
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2
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Loughlin S, Costello HM, Roe AJ, Buckley C, Wilson SM, Bailey MA, Mansley MK. Mapping the Transcriptome Underpinning Acute Corticosteroid Action within the Cortical Collecting Duct. Kidney360 2023; 4:226-240. [PMID: 36821614 PMCID: PMC10103384 DOI: 10.34067/kid.0003582022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 11/08/2022] [Indexed: 11/10/2022]
Abstract
Key Points We report the transcriptomes associated with acute corticosteroid regulation of ENaC activity in polarized mCCDcl1 collecting duct cells. Nine genes were regulated by aldosterone (ALDO), 0 with corticosterone alone, and 151 with corticosterone when 11βHSD2 activity was inhibited. We validated three novel ALDO-induced genes, Rasd1 , Sult1d1 , and Gm43305 , in primary cells isolated from a novel principal cell reporter mouse. Background Corticosteroids regulate distal nephron and collecting duct (CD) Na+ reabsorption, contributing to fluid-volume and blood pressure homeostasis. The transcriptional landscape underpinning the acute stimulation of the epithelial sodium channel (ENaC) by physiological concentrations of corticosteroids remains unclear. Methods Transcriptomic profiles underlying corticosteroid-stimulated ENaC activity in polarized mCCDcl1 cells were generated by coupling electrophysiological measurements of amiloride-sensitive currents with RNAseq. Generation of a principal cell-specific reporter mouse line, mT/mG -Aqp2Cre, enabled isolation of primary CD principal cells by FACS, and ENaC activity was measured in cultured primary cells after acute application of corticosteroids. Expression of target genes was assessed by qRT-PCR in cultured cells or freshly isolated cells after the acute elevation of steroid hormones in mT/mG -Aqp2Cre mice. Results Physiological relevance of the mCCDcl1 model was confirmed with aldosterone (ALDO)-specific stimulation of SGK1 and ENaC activity. Corticosterone (CORT) only modulated these responses at supraphysiological concentrations or when 11βHSD2 was inhibited. When 11βHSD2 protection was intact, CORT caused no significant change in transcripts. We identified a small number of ALDO-induced transcripts associated with stimulated ENaC activity in mCCDcl1 cells and a much larger number with CORT in the absence of 11βHSD2 activity. Principal cells isolated from mT/mG -Aqp2Cre mice were validated and assessment of identified ALDO-induced genes revealed that Sgk1 , Zbtbt16 , Sult1d1 , Rasd1 , and Gm43305 are acutely upregulated by corticosteroids both in vitro and in vivo . Conclusions This study reports the transcriptome of mCCDcl1 cells and identifies a small number of ALDO-induced genes associated with acute stimulation of ENaC, including three previously undescribed genes.
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Affiliation(s)
- Struan Loughlin
- Cellular Medicine Research Division, University of St Andrews, St Andrews, United Kingdom
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Hannah M. Costello
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew J. Roe
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, United Kingdom
| | - Charlotte Buckley
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom
| | - Stuart M. Wilson
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, United Kingdom
| | - Matthew A. Bailey
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
| | - Morag K. Mansley
- Cellular Medicine Research Division, University of St Andrews, St Andrews, United Kingdom
- Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- Division of Pharmacy, School of Medicine, Pharmacy and Health, Durham University Queen's Campus, Stockton-on-Tees, United Kingdom
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3
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Viering DH, Hureaux M, Neveling K, Latta F, Kwint M, Blanchard A, Konrad M, Bindels RJ, Schlingmann KP, Vargas-Poussou R, de Baaij JH. Long-Read Sequencing Identifies Novel Pathogenic Intronic Variants in Gitelman Syndrome. J Am Soc Nephrol 2023; 34:333-345. [PMID: 36302598 PMCID: PMC10103101 DOI: 10.1681/asn.2022050627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/17/2022] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Gitelman syndrome is a salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. It is caused by homozygous recessive or compound heterozygous pathogenic variants in SLC12A3 , which encodes the Na + -Cl - cotransporter (NCC). In up to 10% of patients with Gitelman syndrome, current genetic techniques detect only one specific pathogenic variant. This study aimed to identify a second pathogenic variant in introns, splice sites, or promoters to increase the diagnostic yield. METHODS Long-read sequencing of SLC12A3 was performed in 67 DNA samples from individuals with suspected Gitelman syndrome in whom a single likely pathogenic or pathogenic variant was previously detected. In addition, we sequenced DNA samples from 28 individuals with one variant of uncertain significance or no candidate variant. Midigene splice assays assessed the pathogenicity of novel intronic variants. RESULTS A second likely pathogenic/pathogenic variant was identified in 45 (67%) patients. Those with two likely pathogenic/pathogenic variants had a more severe electrolyte phenotype than other patients. Of the 45 patients, 16 had intronic variants outside of canonic splice sites (nine variants, mostly deep intronic, six novel), whereas 29 patients had an exonic variant or canonic splice site variant. Midigene splice assays of the previously known c.1670-191C>T variant and intronic candidate variants demonstrated aberrant splicing patterns. CONCLUSION Intronic pathogenic variants explain an important part of the missing heritability in Gitelman syndrome. Long-read sequencing should be considered in diagnostic workflows for Gitelman syndrome.
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Affiliation(s)
- Daan H.H.M. Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marguerite Hureaux
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Department of Genetics, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Paris CardioVascular Research Center, Institut National de la Santé et de Recherche Médicale (INSERM) U970, Paris City University, Paris, France
| | - Kornelia Neveling
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Femke Latta
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Michael Kwint
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anne Blanchard
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Clinical Investigations Center, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Centre de Recherche des Cordeliers, Sorbonne Université, INSERM, University of Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - René J.M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies Rénales Héréditaires de l’Enfant et de l’Adulte, MARHEA), Paris, France
- Department of Genetics, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
- Clinical Investigations Center, Hôpital Européen Georges-Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
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Olde Hanhof CJA, Dilmen E, Yousef Yengej FA, Latta F, Ammerlaan CME, Schreurs J, Hooijmaijers L, Jansen J, Rookmaaker MB, Orhon I, Verhaar MC, Hoenderop JG. Differentiated mouse kidney tubuloids as a novel in vitro model to study collecting duct physiology. Front Cell Dev Biol 2023; 11:1086823. [PMID: 36760360 PMCID: PMC9905633 DOI: 10.3389/fcell.2023.1086823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/06/2023] [Indexed: 01/26/2023] Open
Abstract
Kidney tubuloids are cell models that are derived from human or mouse renal epithelial cells and show high similarities with their in vivo counterparts. Tubuloids grow polarized in 3D, allow for long-term expansion, and represent multiple segments of the nephron, as shown by their gene expression pattern. In addition, human tubuloids form tight, functional barriers and have been succesfully used for drug testing. Our knowledge of mouse tubuloids, on the other hand, is only minimal. In this study, we further characterized mouse tubuloids and differentiated them towards the collecting duct, which led to a significant upregulation of collecting duct-specific mRNAs of genes and protein expression, including the water channel AQP2 and the sodium channel ENaC. Differentiation resulted in polarized expression of collecting duct water channels AQP2 and AQP3. Also, a physiological response to desmopressin and forskolin stimulation by translocation of AQP2 to the apical membrane was demonstrated. Furthermore, amiloride-sensitive ENaC-mediated sodium uptake was shown in differentiated tubuloids using radioactive tracer sodium. This study demonstrates that mouse tubuloids can be differentiated towards the collecting duct and exhibit collecting duct-specific function. This illustrates the potential use of mouse kidney tubuloids as novel in vitro models to study (patho)physiology of kidney diseases.
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Affiliation(s)
- C. J. A. Olde Hanhof
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - E. Dilmen
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - F. A. Yousef Yengej
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands,Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - F. Latta
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - C. M. E. Ammerlaan
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands,Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - J. Schreurs
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - L. Hooijmaijers
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - J. Jansen
- Department of Pathology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands,Department of Pediatric Nephrology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Amalia Children’s Hospital, Nijmegen, Netherlands,Institute of Experimental Medicine and Systems Biology, Medical Faculty RWTH Aachen University, Aachen, Germany
| | - M. B. Rookmaaker
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - I. Orhon
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - M. C. Verhaar
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - J. G. Hoenderop
- Department of Molecular Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands,*Correspondence: J. G. Hoenderop,
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Viering D, Schlingmann KP, Hureaux M, Nijenhuis T, Mallett A, Chan MM, van Beek A, van Eerde AM, Coulibaly JM, Vallet M, Decramer S, Pelletier S, Klaus G, Kömhoff M, Beetz R, Patel C, Shenoy M, Steenbergen EJ, Anderson G, Bongers EM, Bergmann C, Panneman D, Rodenburg RJ, Kleta R, Houillier P, Konrad M, Vargas-Poussou R, Knoers NV, Bockenhauer D, de Baaij JH. Gitelman-Like Syndrome Caused by Pathogenic Variants in mtDNA. J Am Soc Nephrol 2022; 33:305-325. [PMID: 34607911 PMCID: PMC8819995 DOI: 10.1681/asn.2021050596] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/06/2021] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Gitelman syndrome is the most frequent hereditary salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. Gitelman syndrome is caused by biallelic pathogenic variants in SLC12A3, encoding the Na+-Cl- cotransporter (NCC) expressed in the distal convoluted tubule. Pathogenic variants of CLCNKB, HNF1B, FXYD2, or KCNJ10 may result in the same renal phenotype of Gitelman syndrome, as they can lead to reduced NCC activity. For approximately 10 percent of patients with a Gitelman syndrome phenotype, the genotype is unknown. METHODS We identified mitochondrial DNA (mtDNA) variants in three families with Gitelman-like electrolyte abnormalities, then investigated 156 families for variants in MT-TI and MT-TF, which encode the transfer RNAs for phenylalanine and isoleucine. Mitochondrial respiratory chain function was assessed in patient fibroblasts. Mitochondrial dysfunction was induced in NCC-expressing HEK293 cells to assess the effect on thiazide-sensitive 22Na+ transport. RESULTS Genetic investigations revealed four mtDNA variants in 13 families: m.591C>T (n=7), m.616T>C (n=1), m.643A>G (n=1) (all in MT-TF), and m.4291T>C (n=4, in MT-TI). Variants were near homoplasmic in affected individuals. All variants were classified as pathogenic, except for m.643A>G, which was classified as a variant of uncertain significance. Importantly, affected members of six families with an MT-TF variant additionally suffered from progressive chronic kidney disease. Dysfunction of oxidative phosphorylation complex IV and reduced maximal mitochondrial respiratory capacity were found in patient fibroblasts. In vitro pharmacological inhibition of complex IV, mimicking the effect of the mtDNA variants, inhibited NCC phosphorylation and NCC-mediated sodium uptake. CONCLUSION Pathogenic mtDNA variants in MT-TF and MT-TI can cause a Gitelman-like syndrome. Genetic investigation of mtDNA should be considered in patients with unexplained Gitelman syndrome-like tubulopathies.
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Affiliation(s)
- Daan Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Karl P. Schlingmann
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Marguerite Hureaux
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France
| | - Tom Nijenhuis
- Department of Nephrology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Andrew Mallett
- Department of Renal Medicine, Townsville University Hospital, Townsville, Australia,Queensland Conjoint Renal Genetics Service – Genetic Health Queensland, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Melanie M.Y. Chan
- Department of Renal Medicine, University College London, London, United Kingdom
| | - André van Beek
- Department of Endocrinology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | | | - Marion Vallet
- Department of Physiological Functional Investigations, Centre Hospitalier Universitaire de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Stéphane Decramer
- Pediatric Nephrology, Internal Medicine and Rheumatology, Southwest Renal Rare Diseases Centre (SORARE), University Children's Hospital, Toulouse, France
| | - Solenne Pelletier
- Department of Nephrology, University Hospital–Lyon Sud, Lyon, France
| | - Günter Klaus
- Kuratorium für Heimdialyse Pediatric Kidney Center, Marburg, Germany
| | - Martin Kömhoff
- University Children's Hospital, Philipps-University, Marburg, Germany
| | - Rolf Beetz
- Johannes Gutenberg Universität Mainz, Zentrum für Kinder- und Jugendmedizin, Mainz, Germany
| | - Chirag Patel
- Queensland Conjoint Renal Genetics Service – Genetic Health Queensland, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Mohan Shenoy
- Department of Paediatric Nephrology, Royal Manchester Children’s Hospital, Manchester, United Kingdom
| | - Eric J. Steenbergen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Glenn Anderson
- Department of Pathology, Great Ormond Street Hospital for Children National Health Service (NHS) Foundation Trust, London, United Kingdom
| | - Ernie M.H.F. Bongers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carsten Bergmann
- Limbach Genetics, Medizinische Genetik Mainz, Prof. Bergmann & Kollegen, Mainz, Germany,Department of Medicine, Division of Nephrology, University Hospital Freiburg, Germany
| | - Daan Panneman
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Pascal Houillier
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Centre de Recherche des Cordeliers, Sorbonne Université, Institut National de la Santé et de Recherche Médicale (INSERM), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France,Department of Physiology, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France,Centre de Recherche des Cordeliers, Sorbonne Université, Institut National de la Santé et de Recherche Médicale (INSERM), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Nine V.A.M. Knoers
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Lakshmipathi J, Gao Y, Hu C, Stuart D, Genzen J, Ramkumar N, Kohan DE. Nephron-Specific Disruption of Polycystin-1 Induces Cyclooxygenase-2-Mediated Blood Pressure Reduction Independent of Cystogenesis. J Am Soc Nephrol 2020; 31:1243-1254. [PMID: 32300065 DOI: 10.1681/asn.2019090934] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/05/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Hypertension often occurs before renal function deteriorates in autosomal dominant polycystic kidney disease (ADPKD). It is unknown whether the Pkd1 gene product polycystin-1-the predominant causal factor in ADPKD-itself contributes to ADPKD hypertension independent of cystogenesis. METHODS We induced nephron-specific disruption of the Pkd1 gene in 3-month-old mice and examined them at 4-5 months of age. RESULTS Kidneys from the Pkd1 knockout mice showed no apparent renal cysts, tubule dilation, or increased cell proliferation. Compared with control mice, Pkd1 knockout mice exhibited reduced arterial pressure during high salt intake; this associated with an increased natriuretic, diuretic, and kaliuretic response during the first 2-3 days of salt loading. The lower arterial pressure and enhanced natriuresis during high salt loading in Pkd1 knockout mice were associated with lower urinary nitrite/nitrate excretion and markedly increased urinary PGE2 excretion, whereas GFR, plasma renin concentration, and urinary endothelin-1 excretion were similar between knockout and control mice. Kidney cyclooxygenase-2 protein levels were increased in Pkd1 knockout mice during high salt intake; administration of NS-398, a selective cyclooxygenase-2 inhibitor, abolished the arterial pressure difference between the knockout and control mice during high salt intake. Total kidney Na+/K+/2Cl- cotransporter isoform 2 (NKCC2) levels were greatly reduced in Pkd1 knockout mice fed a high salt diet compared with controls. CONCLUSIONS These studies suggest that nephron polycystin-1 deficiency does not itself contribute to ADPKD hypertension and that it may, in fact, exert a relative salt-wasting effect. The work seems to comprise the first in vivo studies to describe a potential physiologic role for nephron polycystin-1 in the absence of cysts, tubule dilation, or enhanced cell proliferation.
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Affiliation(s)
| | - Yang Gao
- Division of Nephrology, University of Utah Health Center, Salt Lake City, Utah
| | - Chunyan Hu
- Division of Nephrology, University of Utah Health Center, Salt Lake City, Utah
| | - Deborah Stuart
- Division of Nephrology, University of Utah Health Center, Salt Lake City, Utah
| | - Jonathan Genzen
- Department of Pathology, University of Utah Health Center, Salt Lake City, Utah
| | - Nirupama Ramkumar
- Division of Nephrology, University of Utah Health Center, Salt Lake City, Utah
| | - Donald E Kohan
- Division of Nephrology, University of Utah Health Center, Salt Lake City, Utah
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7
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Hering L, Rahman M, Hoch H, Markó L, Yang G, Reil A, Yakoub M, Gupta V, Potthoff SA, Vonend O, Ralph DL, Gurley SB, McDonough AA, Rump LC, Stegbauer J. α2A-Adrenoceptors Modulate Renal Sympathetic Neurotransmission and Protect against Hypertensive Kidney Disease. J Am Soc Nephrol 2020; 31:783-798. [PMID: 32086277 DOI: 10.1681/asn.2019060599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 12/30/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Increased nerve activity causes hypertension and kidney disease. Recent studies suggest that renal denervation reduces BP in patients with hypertension. Renal NE release is regulated by prejunctional α2A-adrenoceptors on sympathetic nerves, and α2A-adrenoceptors act as autoreceptors by binding endogenous NE to inhibit its own release. However, the role of α2A-adrenoceptors in the pathogenesis of hypertensive kidney disease is unknown. METHODS We investigated effects of α2A-adrenoceptor-regulated renal NE release on the development of angiotensin II-dependent hypertension and kidney disease. In uninephrectomized wild-type and α2A-adrenoceptor-knockout mice, we induced hypertensive kidney disease by infusing AngII for 28 days. RESULTS Urinary NE excretion and BP did not differ between normotensive α2A-adrenoceptor-knockout mice and wild-type mice at baseline. However, NE excretion increased during AngII treatment, with the knockout mice displaying NE levels that were significantly higher than those of wild-type mice. Accordingly, the α2A-adrenoceptor-knockout mice exhibited a systolic BP increase, which was about 40 mm Hg higher than that found in wild-type mice, and more extensive kidney damage. In isolated kidneys, AngII-enhanced renal nerve stimulation induced NE release and pressor responses to a greater extent in kidneys from α2A-adrenoceptor-knockout mice. Activation of specific sodium transporters accompanied the exaggerated hypertensive BP response in α2A-adrenoceptor-deficient kidneys. These effects depend on renal nerves, as demonstrated by reduced severity of AngII-mediated hypertension and improved kidney function observed in α2A-adrenoceptor-knockout mice after renal denervation. CONCLUSIONS Our findings reveal a protective role of prejunctional inhibitory α2A-adrenoceptors in pathophysiologic conditions with an activated renin-angiotensin system, such as hypertensive kidney disease, and support the concept of sympatholytic therapy as a treatment.
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Affiliation(s)
- Lydia Hering
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Masudur Rahman
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Henning Hoch
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Lajos Markó
- Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max Delbruck Center for Molecular Medicine, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Berlin, Germany.,Berlin Institute of Health, Berlin, Germany.,Charité Medical Faculty Berlin, Berlin, Germany
| | - Guang Yang
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,The Shenzhen Key Laboratory of Health Sciences and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, China
| | - Annika Reil
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Mina Yakoub
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Vikram Gupta
- Department of Surgery, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Sebastian A Potthoff
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Oliver Vonend
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Nierenzentrum, DKD Helios Medical Center, Wiesbaden, Germany
| | - Donna L Ralph
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Susan B Gurley
- Division of Nephrology and Hypertension, School of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Alicia A McDonough
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Lars C Rump
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Johannes Stegbauer
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany;
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8
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Leipziger J, Praetorius H. How Does Aldosterone Work in the β-Intercalated Cell? J Am Soc Nephrol 2020; 31:451-452. [PMID: 32065116 DOI: 10.1681/asn.2020010077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Jens Leipziger
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark; and .,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
| | - Helle Praetorius
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark; and
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9
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Wu P, Gao ZX, Su XT, Wang MX, Wang WH, Lin DH. Kir4.1/Kir5.1 Activity Is Essential for Dietary Sodium Intake-Induced Modulation of Na-Cl Cotransporter. J Am Soc Nephrol 2018; 30:216-227. [PMID: 30559144 DOI: 10.1681/asn.2018080799] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 11/13/2018] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Dietary sodium intake regulates the thiazide-sensitive Na-Cl cotransporter (NCC) in the distal convoluted tubule (DCT). Whether the basolateral, inwardly rectifying potassium channel Kir4.1/Kir5.1 (a heterotetramer of Kir4.1/Kir5.1) in the DCT is essential for mediating the effect of dietary sodium intake on NCC activity is unknown. METHODS We used electrophysiology, renal clearance techniques, and immunoblotting to examine effects of Kir4.1/Kir5.1 in the DCT and NCC in wild-type and kidney-specific Kir4.1 knockout mice. RESULTS Low sodium intake stimulated basolateral Kir4.1/Kir5.1 activity, increased basolateral K+ conductance, and hyperpolarized the membrane. Conversely, high sodium intake inhibited the potassium channel, decreased basolateral K+ currents, and depolarized the membrane. Low sodium intake increased total and phosphorylated NCC expression and augmented hydrochlorothiazide-induced natriuresis; high sodium intake had opposite effects. Thus, elevated NCC activity induced by low sodium intake was associated with upregulation of Kir4.1/Kir5.1 activity in the DCT, whereas inhibition of NCC activity by high sodium intake was associated with diminished Kir4.1/Kir5.1 activity. In contrast, dietary sodium intake did not affect NCC activity in knockout mice. Further, Kir4.1 deletion not only abolished basolateral K+ conductance and depolarized the DCT membrane, but also abrogated the stimulating effects induced by low sodium intake on basolateral K+ conductance and hyperpolarization. Finally, dietary sodium intake did not alter urinary potassium excretion rate in hypokalemic knockout and wild-type mice. CONCLUSIONS Stimulation of Kir4.1/Kir5.1 by low intake of dietary sodium is essential for NCC upregulation, and inhibition of Kir4.1/Kir5.1 induced by high sodium intake is a key step for downregulation of NCC.
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Affiliation(s)
- Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Ming-Xiao Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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10
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Livraghi-Butrico A, Wilkinson KJ, Volmer AS, Gilmore RC, Rogers TD, Caldwell RA, Burns KA, Esther CR, Mall MA, Boucher RC, O'Neal WK, Grubb BR. Lung disease phenotypes caused by overexpression of combinations of α-, β-, and γ-subunits of the epithelial sodium channel in mouse airways. Am J Physiol Lung Cell Mol Physiol 2017; 314:L318-L331. [PMID: 29074490 DOI: 10.1152/ajplung.00382.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The epithelial Na+ channel (ENaC) regulates airway surface hydration. In mouse airways, ENaC is composed of three subunits, α, β, and γ, which are differentially expressed (α > β > γ). Airway-targeted overexpression of the β subunit results in Na+ hyperabsorption, causing airway surface dehydration, hyperconcentrated mucus with delayed clearance, lung inflammation, and perinatal mortality. Notably, mice overexpressing the α- or γ-subunit do not exhibit airway Na+ hyperabsorption or lung pathology. To test whether overexpression of multiple ENaC subunits produced Na+ transport and disease severity exceeding that of βENaC-Tg mice, we generated double (αβ, αγ, βγ) and triple (αβγ) transgenic mice and characterized their lung phenotypes. Double αγENaC-Tg mice were indistinguishable from WT littermates. In contrast, double βγENaC-Tg mice exhibited airway Na+ absorption greater than that of βENaC-Tg mice, which was paralleled by worse survival, decreased mucociliary clearance, and more severe lung pathology. Double αβENaC-Tg mice exhibited Na+ transport rates comparable to those of βENaC-Tg littermates. However, αβENaC-Tg mice had poorer survival and developed severe parenchymal consolidation. In situ hybridization (RNAscope) analysis revealed both alveolar and airway αENaC-Tg overexpression. Triple αβγENaC-Tg mice were born in Mendelian proportions but died within the first day of life, and the small sample size prevented analyses of cause(s) of death. Cumulatively, these results indicate that overexpression of βENaC is rate limiting for generation of pathological airway surface dehydration. Notably, airway co-overexpression of β- and γENaC had additive effects on Na+ transport and disease severity, suggesting dose dependency of these two variables.
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Affiliation(s)
- Alessandra Livraghi-Butrico
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Kristen J Wilkinson
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Allison S Volmer
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Rodney C Gilmore
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Troy D Rogers
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | | | - Kimberlie A Burns
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Charles R Esther
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina.,Division of Pediatric Pulmonology, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Marcus A Mall
- Department of Translational Pulmonology, Translational Lung Research Center, Heidelberg, German Center for Lung Research, University of Heidelberg , Heidelberg , Germany.,Division of Pediatric Pulmonology and Allergy and Cystic Fibrosis Center, Dept. of Pediatrics, University of Heidelberg , Heidelberg , Germany
| | - Richard C Boucher
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Wanda K O'Neal
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Barbara R Grubb
- Marsico Lung Institute, University of North Carolina Cystic Fibrosis Center, School of Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
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11
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Affiliation(s)
- Evan C Ray
- Renal-Electrolyte Division, Department of Medicine and
| | | | - Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine and .,Departments of Pharmacology and Chemical Biology and.,Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
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12
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Terker AS, Yarbrough B, Ferdaus MZ, Lazelle RA, Erspamer KJ, Meermeier NP, Park HJ, McCormick JA, Yang CL, Ellison DH. Direct and Indirect Mineralocorticoid Effects Determine Distal Salt Transport. J Am Soc Nephrol 2015; 27:2436-45. [PMID: 26712527 DOI: 10.1681/asn.2015070815] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/17/2015] [Indexed: 11/03/2022] Open
Abstract
Excess aldosterone is an important contributor to hypertension and cardiovascular disease. Conversely, low circulating aldosterone causes salt wasting and hypotension. Aldosterone activates mineralocorticoid receptors (MRs) to increase epithelial sodium channel (ENaC) activity. However, aldosterone may also stimulate the thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC). Here, we generated mice in which MRs could be deleted along the nephron to test this hypothesis. These kidney-specific MR-knockout mice exhibited salt wasting, low BP, and hyperkalemia. Notably, we found evidence of deficient apical orientation and cleavage of ENaC, despite the salt wasting. Although these mice also exhibited deficient NCC activity, NCC could be stimulated by restricting dietary potassium, which also returned BP to control levels. Together, these results indicate that MRs regulate ENaC directly, but modulation of NCC is mediated by secondary changes in plasma potassium concentration. Electrolyte balance and BP seem to be determined, therefore, by a delicate interplay between direct and indirect mineralocorticoid actions in the distal nephron.
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Affiliation(s)
- Andrew S Terker
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Bethzaida Yarbrough
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Mohammed Z Ferdaus
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Rebecca A Lazelle
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Kayla J Erspamer
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Nicholas P Meermeier
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Hae J Park
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
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13
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Borschewski A, Himmerkus N, Boldt C, Blankenstein KI, McCormick JA, Lazelle R, Willnow TE, Jankowski V, Plain A, Bleich M, Ellison DH, Bachmann S, Mutig K. Calcineurin and Sorting-Related Receptor with A-Type Repeats Interact to Regulate the Renal Na⁺-K⁺-2Cl⁻ Cotransporter. J Am Soc Nephrol 2015; 27:107-19. [PMID: 25967121 DOI: 10.1681/asn.2014070728] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 03/16/2015] [Indexed: 01/08/2023] Open
Abstract
The furosemide-sensitive Na(+)-K(+)-2Cl(-)-cotransporter (NKCC2) is crucial for NaCl reabsorption in kidney thick ascending limb (TAL) and drives the urine concentrating mechanism. NKCC2 activity is modulated by N-terminal phosphorylation and dephosphorylation. Serine-threonine kinases that activate NKCC2 have been identified, but less is known about phosphatases that deactivate NKCC2. Inhibition of calcineurin phosphatase has been shown to stimulate transport in the TAL and the distal convoluted tubule. Here, we identified NKCC2 as a target of the calcineurin Aβ isoform. Short-term cyclosporine administration in mice augmented the abundance of phospho-NKCC2, and treatment of isolated TAL with cyclosporine increased the chloride affinity and transport activity of NKCC2. Because sorting-related receptor with A-type repeats (SORLA) may affect NKCC2 phosphoregulation, we used SORLA-knockout mice to test whether SORLA is involved in calcineurin-dependent modulation of NKCC2. SORLA-deficient mice showed more calcineurin Aβ in the apical region of TAL cells and less NKCC2 phosphorylation and activity compared with littermate controls. In contrast, overexpression of SORLA in cultured cells reduced the abundance of endogenous calcineurin Aβ. Cyclosporine administration rapidly normalized the abundance of phospho-NKCC2 in SORLA-deficient mice, and a functional interaction between calcineurin Aβ and SORLA was further corroborated by binding assays in rat kidney extracts. In summary, we have shown that calcineurin Aβ and SORLA are key components in the phosphoregulation of NKCC2. These results may have clinical implications for immunosuppressive therapy using calcineurin inhibitors.
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Affiliation(s)
- Aljona Borschewski
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Christin Boldt
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - James A McCormick
- Division of Nephrology and Hypertension, Oregon Health & Science University and VA Medical Center, Portland, Oregon
| | - Rebecca Lazelle
- Division of Nephrology and Hypertension, Oregon Health & Science University and VA Medical Center, Portland, Oregon
| | - Thomas E Willnow
- Max Delbrueck Center for Molecular Medicine, Berlin, Germany; and
| | - Vera Jankowski
- Medizinische Klinik IV, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Allein Plain
- Institute of Physiology, Kiel University, Kiel, Germany
| | - Markus Bleich
- Institute of Physiology, Kiel University, Kiel, Germany
| | - David H Ellison
- Division of Nephrology and Hypertension, Oregon Health & Science University and VA Medical Center, Portland, Oregon
| | - Sebastian Bachmann
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany;
| | - Kerim Mutig
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany;
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14
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Abstract
This brief review describes some representative methodological approaches to the isolation of putative endogenous inhibitors of epithelial sodium transport - i.e., as ouabain-like factors (OLF) that inhibit the sodium transport enzyme Na-K-ATPase or inhibit the epithelial sodium channel (ENaC). Gel chromatography and reverse-phase (RP)-high performance liquid chromatography (HPLC) of lyophilized and reconstituted 24 h-urine from salt-loaded healthy humans led to two active fractions, a hydrophilic OLF-1 and a lipophilic OLF-2, whose mass (Ms)-spectroscopic data indicate a Mr of 391 (1, 2). Further identification was attempted by Ms-, infrared (IR)-, ultraviolet (UV)-, and (1)H-NMR-spectroscopy. OLF-1 and OLF-2 may be closely related if not identical to (di)ascorbic acid or its salts such as vanadium (V)-V(v)-diascorbate with Mr 403 (3) and V(IV)-diascorbate. OLF-1 and V(v)-diascorbate are about 10-fold stronger inhibitors of Na-K-ATPase than OLF-2 and V(IV)-diascorbate, respectively. In conscious rats, i.v. infusion of OLF-1 and OLF-2 resulted in a strong natriuresis. In a similar study, Cain et al. (4) isolated a sodium transport inhibitor from the urine of uremic patients by gel chromatography and RP-HPLC. In uremic rats, a natriuretic response to the injection of the active material was found. Xanthurenic acid 8-O-β-d-glucoside (Mr 368) and xanthurenic acid 8-O-sulfate (Mr 284) were identified as endogenous inhibitors of sodium transport acting, e.g., by ENaC blockade. No definite relation to blood pressure, body fluid volume, or sodium balance has been reported for any of these above factors, and further studies to identify the natriuretic and/or ouabain-like compound(s) or hormone(s) will be needed.
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Affiliation(s)
- Herbert J. Kramer
- Center of Internal Medicine, Rheinische-Friedrich-Wilhelms-University, Bonn, Germany
- *Correspondence: Herbert J. Kramer, Center of Internal Medicine, Rheinische-Friedrich-Wilhelms-University, Sigmund-Freud-Strasse 25, Bonn D-53127, Germany,
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15
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Mansley MK, Neuhuber W, Korbmacher C, Bertog M. Norepinephrine stimulates the epithelial Na+ channel in cortical collecting duct cells via α2-adrenoceptors. Am J Physiol Renal Physiol 2014; 308:F450-8. [PMID: 25520009 DOI: 10.1152/ajprenal.00548.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
There is good evidence for a causal link between excessive sympathetic drive to the kidney and hypertension. We hypothesized that sympathetic regulation of tubular Na(+) absorption may occur in the aldosterone-sensitive distal nephron, where the fine tuning of renal Na(+) excretion takes place. Here, the appropriate regulation of transepithelial Na(+) transport, mediated by the amiloride-sensitive epithelial Na(+) channel (ENaC), is critical for blood pressure control. To explore a possible effect of the sympathetic transmitter norepinephrine on ENaC-mediated Na(+) transport, we performed short-circuit current (Isc) measurements on confluent mCCDcl1 murine cortical collecting duct cells. Norepinephrine caused a complex Isc response with a sustained increase of amiloride-sensitive Isc by ∼44%. This effect was concentration dependent and mediated via basolateral α2-adrenoceptors. In cells pretreated with aldosterone, the stimulatory effect of norepinephrine was reduced. Finally, we demonstrated that noradrenergic nerve fibers are present in close proximity to ENaC-expressing cells in murine kidney slices. We conclude that the sustained stimulatory effect of locally elevated norepinephrine on ENaC-mediated Na(+) absorption may contribute to the hypertensive effect of increased renal sympathetic activity.
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Affiliation(s)
| | - Winfried Neuhuber
- Lehrstuhl für Anatomie I, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Marko Bertog
- Institut für Zelluläre und Molekulare Physiologie and
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16
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Hunter RW, Ivy JR, Flatman PW, Kenyon CJ, Craigie E, Mullins LJ, Bailey MA, Mullins JJ. Hypertrophy in the Distal Convoluted Tubule of an 11β-Hydroxysteroid Dehydrogenase Type 2 Knockout Model. J Am Soc Nephrol 2014; 26:1537-48. [PMID: 25349206 DOI: 10.1681/asn.2013060634] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 08/12/2014] [Indexed: 11/03/2022] Open
Abstract
Na(+) transport in the renal distal convoluted tubule (DCT) by the thiazide-sensitive NaCl cotransporter (NCC) is a major determinant of total body Na(+) and BP. NCC-mediated transport is stimulated by aldosterone, the dominant regulator of chronic Na(+) homeostasis, but the mechanism is controversial. Transport may also be affected by epithelial remodeling, which occurs in the DCT in response to chronic perturbations in electrolyte homeostasis. Hsd11b2(-/-) mice, which lack the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11βHSD2) and thus exhibit the syndrome of apparent mineralocorticoid excess, provided an ideal model in which to investigate the potential for DCT hypertrophy to contribute to Na(+) retention in a hypertensive condition. The DCTs of Hsd11b2(-/-) mice exhibited hypertrophy and hyperplasia and the kidneys expressed higher levels of total and phosphorylated NCC compared with those of wild-type mice. However, the striking structural and molecular phenotypes were not associated with an increase in the natriuretic effect of thiazide. In wild-type mice, Hsd11b2 mRNA was detected in some tubule segments expressing Slc12a3, but 11βHSD2 and NCC did not colocalize at the protein level. Thus, the phosphorylation status of NCC may not necessarily equate to its activity in vivo, and the structural remodeling of the DCT in the knockout mouse may not be a direct consequence of aberrant corticosteroid signaling in DCT cells. These observations suggest that the conventional concept of mineralocorticoid signaling in the DCT should be revised to recognize the complexity of NCC regulation by corticosteroids.
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Affiliation(s)
- Robert W Hunter
- British Heart Foundation Centre for Cardiovascular Science and
| | - Jessica R Ivy
- British Heart Foundation Centre for Cardiovascular Science and
| | - Peter W Flatman
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Eilidh Craigie
- British Heart Foundation Centre for Cardiovascular Science and
| | - Linda J Mullins
- British Heart Foundation Centre for Cardiovascular Science and
| | | | - John J Mullins
- British Heart Foundation Centre for Cardiovascular Science and
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