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Sakhi I, Bignon Y, Frachon N, Hureaux M, Arévalo B, González W, Vargas-Poussou R, Lourdel S. Diversity of functional alterations of the ClC-5 exchanger in the region of the proton glutamate in patients with Dent disease 1. Hum Mutat 2021; 42:537-550. [PMID: 33600050 DOI: 10.1002/humu.24184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/04/2021] [Accepted: 02/14/2021] [Indexed: 01/21/2023]
Abstract
Mutations in the CLCN5 gene encoding the 2Cl- /1H+ exchanger ClC-5 are associated with Dent disease 1, an inherited renal disorder characterized by low-molecular-weight (LMW) proteinuria and hypercalciuria. In the kidney, ClC-5 is mostly localized in proximal tubule cells, where it is thought to play a key role in the endocytosis of LMW proteins. Here, we investigated the consequences of eight previously reported pathogenic missense mutations of ClC-5 surrounding the "proton glutamate" that serves as a crucial H+ -binding site for the exchanger. A complete loss of function was observed for a group of mutants that were either retained in the endoplasmic reticulum of HEK293T cells or unstainable at plasma membrane due to proteasomal degradation. In contrast, the currents measured for the second group of mutations in Xenopus laevis oocytes were reduced. Molecular dynamics simulations performed on a ClC-5 homology model demonstrated that such mutations might alter ClC-5 protonation by interfering with the water pathway. Analysis of clinical data from patients harboring these mutations demonstrated no phenotype/genotype correlation. This study reveals that mutations clustered in a crucial region of ClC-5 have diverse molecular consequences in patients with Dent disease 1, ranging from altered expression to defects in transport.
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Affiliation(s)
- Imène Sakhi
- Laboratoire Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Yohan Bignon
- Centre Universitaire des Saints Pères, INSERM, Université Paris Descartes, Paris, France
| | - Nadia Frachon
- Laboratoire Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
| | - Marguerite Hureaux
- Département de génétique, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Bárbara Arévalo
- Center for Bioinformatics and Molecular Simulations (CBSM), Universidad de Talca, Talca, Chile
| | - Wendy González
- Center for Bioinformatics and Molecular Simulations (CBSM), Universidad de Talca, Talca, Chile.,Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Talca, Talca, Chile
| | - Rosa Vargas-Poussou
- Laboratoire Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France.,Département de génétique, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Stéphane Lourdel
- Laboratoire Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.,CNRS ERL 8228, Paris, France
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2
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Bignon Y, Alekov A, Frachon N, Lahuna O, Jean-Baptiste Doh-Egueli C, Deschênes G, Vargas-Poussou R, Lourdel S. A novel CLCN5 pathogenic mutation supports Dent disease with normal endosomal acidification. Hum Mutat 2018; 39:1139-1149. [PMID: 29791050 DOI: 10.1002/humu.23556] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/23/2018] [Accepted: 05/19/2018] [Indexed: 12/13/2022]
Abstract
Dent disease is an X-linked recessive renal tubular disorder characterized by low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and progressive renal failure. Inactivating mutations of CLCN5, the gene encoding the 2Cl- /H+ exchanger ClC-5, have been reported in patients with Dent disease 1. In vivo studies in mice harboring an artificial mutation in the "gating glutamate" of ClC-5 (c.632A > C, p.Glu211Ala) and mathematical modeling suggest that endosomal chloride concentration could be an important parameter in endocytosis, rather than acidification as earlier hypothesized. Here, we described a novel pathogenic mutation affecting the "gating glutamate" of ClC-5 (c.632A>G, p.Glu211Gly) and investigated its molecular consequences. In HEK293T cells, the p.Glu211Gly ClC-5 mutant displayed unaltered N-glycosylation and normal plasma membrane and early endosomes localizations. In Xenopus laevis oocytes and HEK293T cells, we found that contrasting with wild-type ClC-5, the mutation abolished the outward rectification, the sensitivity to extracellular H+ and converted ClC-5 into a Cl- channel. Investigation of endosomal acidification in HEK293T cells using the pH-sensitive pHluorin2 probe showed that the luminal pH of cells expressing a wild-type or p.Glu211Gly ClC-5 was not significantly different. Our study further confirms that impaired acidification of endosomes is not the only parameter leading to defective endocytosis in Dent disease 1.
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Affiliation(s)
- Yohan Bignon
- Sorbonne Université, Université Paris-Descartes, INSERM, CNRS, Paris, France
| | - Alexi Alekov
- Institut für Neurophysiologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Nadia Frachon
- Sorbonne Université, Université Paris-Descartes, INSERM, CNRS, Paris, France
| | | | | | - Georges Deschênes
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Service de Néphrologie Pédiatrique, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
| | - Rosa Vargas-Poussou
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Département de génétique, Paris, France.,Université Paris-Descartes, Faculté de Médecine, Paris, France
| | - Stéphane Lourdel
- Sorbonne Université, Université Paris-Descartes, INSERM, CNRS, Paris, France
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3
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George SK, Abolbashari M, Jackson JD, Aboushwareb T, Atala A, Yoo JJ. Potential Use of Autologous Renal Cells from Diseased Kidneys for the Treatment of Renal Failure. PLoS One 2016; 11:e0164997. [PMID: 27776163 PMCID: PMC5077100 DOI: 10.1371/journal.pone.0164997] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 10/04/2016] [Indexed: 12/17/2022] Open
Abstract
Chronic kidney disease (CKD) occurs when certain conditions cause the kidneys to gradually lose function. For patients with CKD, renal transplantation is the only treatment option that restores kidney function. In this study, we evaluated primary renal cells obtained from diseased kidneys to determine whether their normal phenotypic and functional characteristics are retained, and could be used for cell therapy. Primary renal cells isolated from both normal kidneys (NK) and diseased kidneys (CKD) showed similar phenotypic characteristics and growth kinetics. The expression levels of renal tubular cell markers, Aquaporin-1 and E-Cadherin, and podocyte-specific markers, WT-1 and Nephrin, were similar in both NK and CKD kidney derived cells. Using fluorescence- activated cell sorting (FACS), specific renal cell populations were identified and included proximal tubular cells (83.1% from NK and 80.3% from CKD kidneys); distal tubular cells (11.03% from NK and 10.9% from CKD kidneys); and podocytes (1.91% from NK and 1.78% from CKD kidneys). Ultra-structural analysis using scanning electron microscopy (SEM) revealed microvilli on the apical surface of cultured cells from NK and CKD samples. Moreover, transmission electron microscopy (TEM) analysis showed a similar organization of tight junctions, desmosomes, and other intracellular structures. The Na+ uptake characteristics of NK and CKD derived renal cells were also similar (24.4 mmol/L and 25 mmol/L, respectively) and no significant differences were observed in the protein uptake and transport characteristics of these two cell isolates. These results show that primary renal cells derived from diseased kidneys such as CKD have similar structural and functional characteristics to their counterparts from a normal healthy kidney (NK) when grown in vitro. This study suggests that cells derived from diseased kidney may be used as an autologous cell source for renal cell therapy, particularly in patients with CKD or end-stage renal disease (ESRD).
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Affiliation(s)
- Sunil K. George
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, United States of America
| | - Mehran Abolbashari
- Texas Tech University, Paul L. Foster School of Medicine, El Paso, Texas, 79905, United States of America
| | - John D. Jackson
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, United States of America
| | - Tamer Aboushwareb
- RSS Urology—Mid Atlantic, Allergan Medical Affairs, P.O. Box 19534, Irvine, California, 92623, United States of America
| | - Anthony Atala
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, United States of America
| | - James J. Yoo
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina, 27157, United States of America
- * E-mail:
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4
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Briffa JF, Grinfeld E, Jenkin KA, Mathai ML, Poronnik P, McAinch AJ, Hryciw DH. Diet induced obesity in rats reduces NHE3 and Na(+) /K(+) -ATPase expression in the kidney. Clin Exp Pharmacol Physiol 2016; 42:1118-26. [PMID: 26173747 DOI: 10.1111/1440-1681.12452] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 06/25/2015] [Accepted: 07/01/2015] [Indexed: 01/25/2023]
Abstract
The consumption of a high fat diet (HFD) is associated with proteinuria and altered sodium handling and excretion, which can lead to kidney disease. In the proximal tubule, the Na(+) /H(+) Exchanger 3 (NHE3) is responsible for normal protein reabsorption and the reabsorption of approximately 70% of the renal sodium load. It is the Na(+) /K(+) -ATPase that provides the driving force for the reabsorption of sodium and its exit across the basolateral membrane. This study investigates the effects that consumption of a HFD for 12 weeks has on NHE3 and Na(+) /K(+) -ATPase expression in the kidney. Western blot analysis identified a significant reduction in NHE3 and its modulator, phosphorylated protein kinase B, in renal lysate from obese rats. In the obese rats, a reduction in NHE3 expression in the proximal tubule may impact on the acidification of endosomes which are responsible for albumin uptake, suggesting a key role for the exchanger in protein endocytosis in obesity. Western blot analysis identified a reduction in Na(+) /K(+) -ATPase which could also potentially impact on albumin uptake and sodium reabsorption. This study demonstrates that consumption of a HFD for 12 weeks reduces renal NHE3 and Na(+) /K(+) -ATPase expression, an effect that may contribute to the albuminuria associated with obesity. Furthermore the reduction in these transporters is not likely to contribute to the reduced sodium excretion in obesity. These data highlight a potential link between NHE3 and Na(+) /K(+) -ATPase in the pathophysiological changes in renal protein handling observed in obesity.
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Affiliation(s)
- J F Briffa
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Victoria, Australia.,Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - E Grinfeld
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Victoria, Australia
| | - K A Jenkin
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Victoria, Australia
| | - M L Mathai
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Victoria, Australia
| | - P Poronnik
- Department of Physiology, School of Medical Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - A J McAinch
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Victoria, Australia
| | - D H Hryciw
- Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia
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5
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Lang F, Stournaras C, Alesutan I. Regulation of transport across cell membranes by the serum- and glucocorticoid-inducible kinase SGK1. Mol Membr Biol 2014; 31:29-36. [PMID: 24417516 DOI: 10.3109/09687688.2013.874598] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The serum- and glucocorticoid-inducible kinase 1 (SGK1) is genomically upregulated by cell stress including energy depletion and hyperosmotic shock as well as a variety of hormones including glucocorticoids, mineralocorticoids and TGFβ. SGK1 is activated by insulin, growth factors and oxidative stress via phosphatidylinositide-3-kinase, 3-phosphoinositide-dependent kinase PDK1 and mTOR. SGK1 is a powerful stimulator of Na(+)/K(+)-ATPase, carriers (e.g., NCC, NKCC, NHE1, NHE3, SGLT1, several amino acid transporters) and ion channels (e.g., ENaC, SCN5A, TRPV4-6, ORAI1/STIM1, ROMK, KCNE1/KCNQ1, GluR6, CFTR). Mechanisms employed by SGK1 in transport regulation include direct phosphorylation of target transport proteins, phosphorylation and thus activation of other transport regulating kinases, stabilization of membrane proteins by phosphorylation and thus inactivation of the ubiquitin ligase NEDD4-2, as well as stimulation of transport protein expression by upregulation transcription factors (e.g., nuclear factor kappa-B [NFκB]) and by fostering of protein translation. SGK1 sensitivity of pump, carrier and channel activities participate in the regulation of epithelial transport, cardiac and neuronal excitability, degranulation, platelet function, migration, cell proliferation and apoptosis. SGK1-sensitive functions do not require the presence of SGK1 but are markedly upregulated by SGK1. Accordingly, the phenotype of SGK1 knockout mice is mild. The mice are, however, less sensitive to excessive activation of transport by glucocorticoids, mineralocorticoids, insulin and inflammation. Moreover, excessive SGK1 activity contributes to the pathophysiology of hypertension, obesity, diabetes, thrombosis, stroke, inflammation, autoimmune disease, fibrosis and tumor growth.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tübingen , Germany and
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Pasham V, Rotte A, Gu S, Yang W, Bhandaru M, Rexhepaj R, Pathare G, Lang F. Upregulation of intestinal NHE3 following saline ingestion. Kidney Blood Press Res 2013; 37:48-57. [PMID: 23548792 DOI: 10.1159/000343401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/19/2013] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Little is known about the effect of salt content of ingested fluid on intestinal transport processes. Osmosensitive genes include the serum- and glucocorticoid-inducible kinase SGK1, which is up-regulated by hyperosmolarity and cell shrinkage. SGK1 is in turn a powerful stimulator of the intestinal Na(+)/H(+) exchanger NHE3. The present study was thus performed to elucidate, whether the NaCl content of beverages influences NHE3 activity. METHODS Mice were offered access to either plain water or isotonic saline ad libitum. NHE3 transcript levels and protein abundance in intestinal tissue were determined by confocal immunofluorescent microscopy, RT-PCR and western blotting, cytosolic pH (pHi) in intestinal cells from 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) fluorescence and Na(+)/H(+) exchanger activity from the Na(+) dependent realkalinization following an ammonium pulse. RESULTS Saline drinking significantly enhanced fluid intake and increased NHE3 transcript levels, NHE3 protein and Na(+)/H(+) exchanger activity. CONCLUSIONS Salt content of ingested fluid has a profound effect on intestinal Na(+)/H(+) exchanger expression and activity.
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Affiliation(s)
- Venkanna Pasham
- Department of Physiology, University of Tübingen, Tübingen, Germany
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