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Sassi A, Wang Y, Chassot A, Komarynets O, Roth I, Olivier V, Crambert G, Dizin E, Boscardin E, Hummler E, Feraille E. Interaction between Epithelial Sodium Channel γ-Subunit and Claudin-8 Modulates Paracellular Sodium Permeability in Renal Collecting Duct. J Am Soc Nephrol 2020; 31:1009-1023. [PMID: 32245797 DOI: 10.1681/asn.2019080790] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 02/15/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Water and solute transport across epithelia can occur via the transcellular or paracellular pathways. Tight junctions play a key role in mediating paracellular ion reabsorption in the kidney. In the renal collecting duct, which is a typical absorptive tight epithelium, coordination between transcellular sodium reabsorption and paracellular permeability may prevent the backflow of reabsorbed sodium to the tubular lumen along a steep electrochemical gradient. METHODS To investigate whether transcellular sodium transport controls tight-junction composition and paracellular permeability via modulating expression of the transmembrane protein claudin-8, we used cultured mouse cortical collecting duct cells to see how overexpression or silencing of epithelial sodium channel (ENaC) subunits and claudin-8 affect paracellular permeability. We also used conditional kidney tubule-specific knockout mice lacking ENaC subunits to assess the ENaC's effect on claudin-8 expression. RESULTS Overexpression or silencing of the ENaC γ-subunit was associated with parallel and specific changes in claudin-8 abundance. Increased claudin-8 abundance was associated with a reduction in paracellular permeability to sodium, whereas decreased claudin-8 abundance was associated with the opposite effect. Claudin-8 overexpression and silencing reproduced these functional effects on paracellular ion permeability. Conditional kidney tubule-specific ENaC γ-subunit knockout mice displayed decreased claudin-8 expression, confirming the cell culture experiments' findings. Importantly, ENaC β-subunit or α-subunit silencing or kidney tubule-specific β-ENaC or α-ENaC knockout mice did not alter claudin-8 abundance. CONCLUSIONS Our data reveal the specific coupling between ENaC γ-subunit and claudin-8 expression. This coupling may play an important role in preventing the backflow of reabsorbed solutes and water to the tubular lumen, as well as in coupling paracellular and transcellular sodium permeability.
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Affiliation(s)
- Ali Sassi
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland.,National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Yubao Wang
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland.,National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Alexandra Chassot
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland.,National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Olga Komarynets
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland
| | - Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland
| | - Valérie Olivier
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland.,National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Gilles Crambert
- Sorbonne University, Unité Mixte de Recherche (UMR) S1138, Cordeliers Research Center, Paris, France
| | - Eva Dizin
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland.,National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
| | - Emilie Boscardin
- National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland.,Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Eric Feraille
- Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland .,National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland
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Canonica J, Frateschi S, Boscardin E, Ebering A, Sergi C, Jäger Y, Peyrollaz T, Mérillat AM, Maillard M, Klusonova P, Odermatt A, Koesters R, Debonneville A, Staub O, Verouti SN, Hummler E. Lack of Renal Tubular Glucocorticoid Receptor Decreases the Thiazide-Sensitive Na +/Cl - Cotransporter NCC and Transiently Affects Sodium Handling. Front Physiol 2019; 10:989. [PMID: 31474871 PMCID: PMC6702950 DOI: 10.3389/fphys.2019.00989] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 07/18/2019] [Indexed: 12/14/2022] Open
Abstract
Chronic glucocorticoid infusion impairs NCC activity and induces a non-dipping profile in mice, suggesting that glucocorticoids are essential for daily blood pressure variations. In this paper, we studied mice lacking the renal tubular glucocorticoid receptor (GR) in adulthood (GR knockouts, Nr3c1Pax8/LC1). Upon standard salt diet, Nr3c1Pax8/LC1 mice grow normally, but show reduced NCC activity despite normal plasma aldosterone levels. Following diet switch to low sodium, Nr3c1Pax8/LC1 mice exhibit a transient but significant reduction in the activity of NCC and expression of NHE3 and NKCC2 accompanied by significant increased Spak activity. This is followed by transiently increased urinary sodium excretion and higher plasma aldosterone concentrations. Plasma corticosterone levels and 11βHSD2 mRNA expression and activity in the whole kidney remain unchanged. High salt diet does not affect whole body Na+ and/or K+ balance and NCC activity is not reduced, but leads to a significant increase in diastolic blood pressure dipping in Nr3c1Pax8/LC1 mice. When high sodium treatment is followed by 48 h of darkness, NCC abundance is reduced in knockout mice although activity is not different. Our data show that upon Na+ restriction renal tubular GR-deficiency transiently affects Na+ handling and transport pathways. Overall, upon standard, low Na+ and high Na+ diet exposure Na+ and K+ balance is maintained as evidenced by normal plasma and urinary Na+ and K+ and aldosterone concentrations.
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Affiliation(s)
- Jérémie Canonica
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Simona Frateschi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Anna Ebering
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Chloé Sergi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Yannick Jäger
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Thibaud Peyrollaz
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Anne-Marie Mérillat
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Marc Maillard
- Department of Nephrology Service, University Hospital of Lausanne (CHUV), Lausanne, Switzerland
| | - Petra Klusonova
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Alex Odermatt
- National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland.,Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Robert Koesters
- Hôpital Tenon, Université Pierre et Marie Curie, Paris, France
| | - Anne Debonneville
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Sophia N Verouti
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
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Boscardin E, Perrier R, Sergi C, Maillard MP, Loffing J, Loffing-Cueni D, Koesters R, Rossier BC, Hummler E. Plasma Potassium Determines NCC Abundance in Adult Kidney-Specific γENaC Knockout. J Am Soc Nephrol 2018; 29:977-990. [PMID: 29371419 DOI: 10.1681/asn.2017030345] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 11/30/2017] [Indexed: 12/18/2022] Open
Abstract
The amiloride-sensitive epithelial sodium channel (ENaC) and the thiazide-sensitive sodium chloride cotransporter (NCC) are key regulators of sodium and potassium and colocalize in the late distal convoluted tubule of the kidney. Loss of the αENaC subunit leads to a perinatal lethal phenotype characterized by sodium loss and hyperkalemia resembling the human syndrome pseudohypoaldosteronism type 1 (PHA-I). In adulthood, inducible nephron-specific deletion of αENaC in mice mimics the lethal phenotype observed in neonates, and as in humans, this phenotype is prevented by a high sodium (HNa+)/low potassium (LK+) rescue diet. Rescue reflects activation of NCC, which is suppressed at baseline by elevated plasma potassium concentration. In this study, we investigated the role of the γENaC subunit in the PHA-I phenotype. Nephron-specific γENaC knockout mice also presented with salt-wasting syndrome and severe hyperkalemia. Unlike mice lacking αENaC or βΕΝaC, an HNa+/LK+ diet did not normalize plasma potassium (K+) concentration or increase NCC activation. However, when K+ was eliminated from the diet at the time that γENaC was deleted, plasma K+ concentration and NCC activity remained normal, and progressive weight loss was prevented. Loss of the late distal convoluted tubule, as well as overall reduced βENaC subunit expression, may be responsible for the more severe hyperkalemia. We conclude that plasma K+ concentration becomes the determining and limiting factor in regulating NCC activity, regardless of Na+ balance in γENaC-deficient mice.
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Affiliation(s)
- Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Center of Competence in Research "Kidney.Control of Homeostasis," Lausanne and Zurich, Switzerland
| | - Romain Perrier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Chloé Sergi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Marc P Maillard
- Service of Nephrology, University Hospital of Lausanne, Lausanne, Switzerland
| | - Johannes Loffing
- National Center of Competence in Research "Kidney.Control of Homeostasis," Lausanne and Zurich, Switzerland.,Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | | | - Robert Koesters
- Department of Nephrology, Hôpital Tenon, Université Pierre et Marie Curie, Paris, France
| | - Bernard C Rossier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; .,National Center of Competence in Research "Kidney.Control of Homeostasis," Lausanne and Zurich, Switzerland
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Boscardin E, Perrier R, Sergi C, Maillard M, Loffing J, Loffing-Cueni D, Koesters R, Rossier BC, Hummler E. Severe hyperkalemia is rescued by low-potassium diet in renal βENaC-deficient mice. Pflugers Arch 2017; 469:1387-1399. [DOI: 10.1007/s00424-017-1990-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 04/07/2017] [Accepted: 04/26/2017] [Indexed: 12/31/2022]
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Boscardin E, Alijevic O, Hummler E, Frateschi S, Kellenberger S. The function and regulation of acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC): IUPHAR Review 19. Br J Pharmacol 2016; 173:2671-701. [PMID: 27278329 DOI: 10.1111/bph.13533] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/19/2016] [Accepted: 06/02/2016] [Indexed: 12/30/2022] Open
Abstract
Acid-sensing ion channels (ASICs) and the epithelial Na(+) channel (ENaC) are both members of the ENaC/degenerin family of amiloride-sensitive Na(+) channels. ASICs act as proton sensors in the nervous system where they contribute, besides other roles, to fear behaviour, learning and pain sensation. ENaC mediates Na(+) reabsorption across epithelia of the distal kidney and colon and of the airways. ENaC is a clinically used drug target in the context of hypertension and cystic fibrosis, while ASIC is an interesting potential target. Following a brief introduction, here we will review selected aspects of ASIC and ENaC function. We discuss the origin and nature of pH changes in the brain and the involvement of ASICs in synaptic signalling. We expose how in the peripheral nervous system, ASICs cover together with other ion channels a wide pH range as proton sensors. We introduce the mechanisms of aldosterone-dependent ENaC regulation and the evidence for an aldosterone-independent control of ENaC activity, such as regulation by dietary K(+) . We then provide an overview of the regulation of ENaC by proteases, a topic of increasing interest over the past few years. In spite of the profound differences in the physiological and pathological roles of ASICs and ENaC, these channels share many basic functional and structural properties. It is likely that further research will identify physiological contexts in which ASICs and ENaC have similar or overlapping roles.
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Affiliation(s)
- Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Omar Alijevic
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
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Perrier R, Boscardin E, Malsure S, Sergi C, Maillard MP, Loffing J, Loffing-Cueni D, Sørensen MV, Koesters R, Rossier BC, Frateschi S, Hummler E. Severe Salt-Losing Syndrome and Hyperkalemia Induced by Adult Nephron-Specific Knockout of the Epithelial Sodium Channel α-Subunit. J Am Soc Nephrol 2015; 27:2309-18. [PMID: 26701978 DOI: 10.1681/asn.2015020154] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [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: 02/11/2015] [Accepted: 10/28/2015] [Indexed: 11/03/2022] Open
Abstract
Systemic pseudohypoaldosteronism type 1 (PHA-1) is a severe salt-losing syndrome caused by loss-of-function mutations of the amiloride-sensitive epithelial sodium channel (ENaC) and characterized by neonatal life-threatening hypovolemia and hyperkalemia. The very high plasma aldosterone levels detected under hypovolemic or hyperkalemic challenge can lead to increased or decreased sodium reabsorption, respectively, through the Na(+)/Cl(-) cotransporter (NCC). However, the role of ENaC deficiency remains incompletely defined, because constitutive inactivation of individual ENaC subunits is neonatally lethal in mice. We generated adult inducible nephron-specific αENaC-knockout mice (Scnn1a(Pax8/LC1)) that exhibit hyperkalemia and body weight loss when kept on a regular-salt diet, thus mimicking PHA-1. Compared with control mice fed a regular-salt diet, knockout mice fed a regular-salt diet exhibited downregulated expression and phosphorylation of NCC protein, despite high plasma aldosterone levels. In knockout mice fed a high-sodium and reduced-potassium diet (rescue diet), although plasma aldosterone levels remained significantly increased, NCC expression returned to control levels, and body weight, plasma and urinary electrolyte concentrations, and excretion normalized. Finally, shift to a regular diet after the rescue diet reinstated the symptoms of severe PHA-1 syndrome and significantly reduced NCC phosphorylation. In conclusion, lack of ENaC-mediated sodium transport along the nephron cannot be compensated for by other sodium channels and/or transporters, only by a high-sodium and reduced-potassium diet. We further conclude that hyperkalemia becomes the determining factor in regulating NCC activity, regardless of sodium loss, in the ENaC-mediated salt-losing PHA-1 phenotype.
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Affiliation(s)
- Romain Perrier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; Swiss National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Sumedha Malsure
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Chloé Sergi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Marc P Maillard
- Service of Nephrology Department, University Hospital of Lausanne, Lausanne, Switzerland
| | - Johannes Loffing
- Swiss National Center of Competence in Research "Kidney.CH", Zurich, Switzerland; Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Dominique Loffing-Cueni
- Swiss National Center of Competence in Research "Kidney.CH", Zurich, Switzerland; Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Mads Vaarby Sørensen
- Swiss National Center of Competence in Research "Kidney.CH", Zurich, Switzerland; Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Robert Koesters
- Department of Nephrology, Hôpital Tenon, Université Pierre et Marie Curie, Paris, France
| | - Bernard C Rossier
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland;
| | - Simona Frateschi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; Swiss National Center of Competence in Research "Kidney.CH", Zurich, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland; Swiss National Center of Competence in Research "Kidney.CH", Zurich, Switzerland;
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Verouti SN, Boscardin E, Hummler E, Frateschi S. Regulation of blood pressure and renal function by NCC and ENaC: lessons from genetically engineered mice. Curr Opin Pharmacol 2015; 21:60-72. [PMID: 25613995 DOI: 10.1016/j.coph.2014.12.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 12/22/2014] [Accepted: 12/22/2014] [Indexed: 01/01/2023]
Abstract
The activity of the thiazide-sensitive Na(+)/Cl(-) cotransporter (NCC) and of the amiloride-sensitive epithelial Na(+) channel (ENaC) is pivotal for blood pressure regulation. NCC is responsible for Na(+) reabsorption in the distal convoluted tubule (DCT) of the nephron, while ENaC reabsorbs the filtered Na(+) in the late DCT and in the cortical collecting ducts (CCD) providing the final renal adjustment to Na(+) balance. Here, we aim to highlight the recent advances made using transgenic mouse models towards the understanding of the regulation of NCC and ENaC function relevant to the control of sodium balance and blood pressure. We thus like to pave the way for common mechanisms regulating these two sodium-transporting proteins and their potential implication in structural remodeling of the nephron segments and Na(+) and Cl(-) reabsorption.
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Affiliation(s)
- Sophia N Verouti
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
| | - Simona Frateschi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
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