1
|
de Combiens E, Sakhi IB, Lourdel S. A Focus on the Proximal Tubule Dysfunction in Dent Disease Type 1. Genes (Basel) 2024; 15:1175. [PMID: 39336766 PMCID: PMC11431675 DOI: 10.3390/genes15091175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Revised: 08/28/2024] [Accepted: 09/05/2024] [Indexed: 09/30/2024] Open
Abstract
Dent disease type 1 is a rare X-linked recessive inherited renal disorder affecting mainly young males, generally leading to end-stage renal failure and for which there is no cure. It is caused by inactivating mutations in the gene encoding ClC-5, a 2Cl-/H+ exchanger found on endosomes in the renal proximal tubule. This transporter participates in reabsorbing all filtered plasma proteins, which justifies why proteinuria is commonly observed when ClC-5 is defective. In the context of Dent disease type 1, a proximal tubule dedifferentiation was shown to be accompanied by a dysfunctional cell metabolism. However, the exact mechanisms linking such alterations to chronic kidney disease are still unclear. In this review, we gather knowledge from several Dent disease type 1 models to summarize the current hypotheses generated to understand the progression of this disorder. We also highlight some urinary biomarkers for Dent disease type 1 suggested in different studies.
Collapse
Affiliation(s)
- Elise de Combiens
- Laboratoire de Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale (INSERM), Sorbonne Université, Université Paris Cité, F-75006 Paris, France; (E.d.C.); (S.L.)
- Unité Métabolisme et Physiologie Rénale, Centre National de la Recherche Scientifique (CNRS) EMR8228, F-75006 Paris, France
| | | | - Stéphane Lourdel
- Laboratoire de Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale (INSERM), Sorbonne Université, Université Paris Cité, F-75006 Paris, France; (E.d.C.); (S.L.)
- Unité Métabolisme et Physiologie Rénale, Centre National de la Recherche Scientifique (CNRS) EMR8228, F-75006 Paris, France
| |
Collapse
|
2
|
Wang Y, Xu L, Zhang Y, Fu H, Gao L, Guan Y, Gu W, Sun J, Chen X, Yang F, Lai E, Wang J, Jin Y, Kou Z, Qiu X, Mao J, Hu L. Dent disease 1-linked novel CLCN5 mutations result in aberrant location and reduced ion currents. Int J Biol Macromol 2024; 257:128564. [PMID: 38061527 DOI: 10.1016/j.ijbiomac.2023.128564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 11/12/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023]
Abstract
Dent disease is a rare renal tubular disease with X-linked recessive inheritance characterized by low molecular weight proteinuria (LMWP), hypercalciuria, and nephrocalcinosis. Mutations disrupting the 2Cl-/1H+ exchange activity of chloride voltage-gated channel 5 (CLCN5) have been causally linked to the most common form, Dent disease 1 (DD1), although the pathophysiological mechanisms remain unclear. Here, we conducted the whole exome capture sequencing and bioinformatics analysis within our DD1 cohort to identify two novel causal mutations in CLCN5 (c.749 G > A, p. G250D, c.829 A > C, p. T277P). Molecular dynamics simulations of ClC-5 homology model suggested that these mutations potentially may induce structural changes, destabilizing ClC-5. Overexpression of variants in vitro revealed aberrant subcellular localization in the endoplasmic reticulum (ER), significant accumulation of insoluble aggregates, and disrupted ion transport function in voltage clamp recordings. Moreover, human kidney-2 (HK-2) cells overexpressing either G250D or T277P displayed higher cell-substrate adhesion, migration capability but reduced endocytic function, as well as substantially altered transcriptomic profiles with G250D resulting in stronger deleterious effects. These cumulative findings supported pathogenic role of these ClC-5 mutations in DD1 and suggested a cellular mechanism for disrupted renal function in Dent disease patients, as well as a potential target for diagnostic biomarker or therapeutic strategy development.
Collapse
Affiliation(s)
- Yan Wang
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Lizhen Xu
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Ying Zhang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
| | - Haidong Fu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Langping Gao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yuelin Guan
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Weizhong Gu
- Department of Pathology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Jingmiao Sun
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou 310020, China
| | - Fan Yang
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - EnYin Lai
- Department of Physiology School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Jingjing Wang
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yanyan Jin
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Ziqi Kou
- Institute for Brain Research and Rehabilitation, and Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou 510631, China
| | - Xingyu Qiu
- Department of Physiology School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China.
| | - Lidan Hu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China.
| |
Collapse
|
3
|
Bondue T, Arcolino FO, Veys KRP, Adebayo OC, Levtchenko E, van den Heuvel LP, Elmonem MA. Urine-Derived Epithelial Cells as Models for Genetic Kidney Diseases. Cells 2021; 10:cells10061413. [PMID: 34204173 PMCID: PMC8230018 DOI: 10.3390/cells10061413] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 12/11/2022] Open
Abstract
Epithelial cells exfoliated in human urine can include cells anywhere from the urinary tract and kidneys; however, podocytes and proximal tubular epithelial cells (PTECs) are by far the most relevant cell types for the study of genetic kidney diseases. When maintained in vitro, they have been proven extremely valuable for discovering disease mechanisms and for the development of new therapies. Furthermore, cultured patient cells can individually represent their human sources and their specific variants for personalized medicine studies, which are recently gaining much interest. In this review, we summarize the methodology for establishing human podocyte and PTEC cell lines from urine and highlight their importance as kidney disease cell models. We explore the well-established and recent techniques of cell isolation, quantification, immortalization and characterization, and we describe their current and future applications.
Collapse
Affiliation(s)
- Tjessa Bondue
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
| | - Fanny O. Arcolino
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
| | - Koenraad R. P. Veys
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Oyindamola C. Adebayo
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Elena Levtchenko
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Lambertus P. van den Heuvel
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatric Nephrology, Radboud University Medical Center, 6500 Nijmegen, The Netherlands
| | - Mohamed A. Elmonem
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo 11628, Egypt
- Correspondence:
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Grieschat M, Guzman RE, Langschwager K, Fahlke C, Alekov AK. Metabolic energy sensing by mammalian CLC anion/proton exchangers. EMBO Rep 2020; 21:e47872. [PMID: 32390228 PMCID: PMC7271328 DOI: 10.15252/embr.201947872] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 01/26/2020] [Accepted: 01/29/2020] [Indexed: 12/13/2022] Open
Abstract
CLC anion/proton exchangers control the pH and [Cl- ] of the endolysosomal system that is essential for cellular nutrient uptake. Here, we use heterologous expression and whole-cell electrophysiology to investigate the regulation of the CLC isoforms ClC-3, ClC-4, and ClC-5 by the adenylic system components ATP, ADP, and AMP. Our results show that cytosolic ATP and ADP but not AMP and Mg2+ -free ADP enhance CLC ion transport. Biophysical analysis reveals that adenine nucleotides alter the ratio between CLC ion transport and CLC gating charge and shift the CLC voltage-dependent activation. The latter effect is suppressed by blocking the intracellular entrance of the proton transport pathway. We suggest, therefore, that adenine nucleotides regulate the internal proton delivery into the CLC transporter machinery and alter the probability of CLC transporters to undergo silent non-transporting cycles. Our findings suggest that the CBS domains in mammalian CLC transporters serve as energy sensors that regulate vesicular Cl- /H+ exchange by detecting changes in the cytosolic ATP/ADP/AMP equilibrium. Such sensing mechanism links the endolysosomal activity to the cellular metabolic state.
Collapse
Affiliation(s)
| | - Raul E Guzman
- Institute of Complex SystemsZelluläre Biophysik (ICS‐4), Forschungszentrum JülichJülichGermany
| | | | - Christoph Fahlke
- Institute of Complex SystemsZelluläre Biophysik (ICS‐4), Forschungszentrum JülichJülichGermany
| | - Alexi K Alekov
- Institute of NeurophysiologyHannover Medical SchoolHannoverGermany
| |
Collapse
|
6
|
Leisle L, Xu Y, Fortea E, Lee S, Galpin JD, Vien M, Ahern CA, Accardi A, Bernèche S. Divergent Cl - and H + pathways underlie transport coupling and gating in CLC exchangers and channels. eLife 2020; 9:e51224. [PMID: 32343228 PMCID: PMC7274781 DOI: 10.7554/elife.51224] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 04/28/2020] [Indexed: 12/12/2022] Open
Abstract
The CLC family comprises H+-coupled exchangers and Cl- channels, and mutations causing their dysfunction lead to genetic disorders. The CLC exchangers, unlike canonical 'ping-pong' antiporters, simultaneously bind and translocate substrates through partially congruent pathways. How ions of opposite charge bypass each other while moving through a shared pathway remains unknown. Here, we use MD simulations, biochemical and electrophysiological measurements to identify two conserved phenylalanine residues that form an aromatic pathway whose dynamic rearrangements enable H+ movement outside the Cl- pore. These residues are important for H+ transport and voltage-dependent gating in the CLC exchangers. The aromatic pathway residues are evolutionarily conserved in CLC channels where their electrostatic properties and conformational flexibility determine gating. We propose that Cl- and H+ move through physically distinct and evolutionarily conserved routes through the CLC channels and transporters and suggest a unifying mechanism that describes the gating mechanism of both CLC subtypes.
Collapse
Affiliation(s)
- Lilia Leisle
- Department of Anesthesiology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Yanyan Xu
- SIB Swiss Institute of Bioinformatics, University of BaselBaselSwitzerland
- Biozentrum, University of BaselBaselSwitzerland
| | - Eva Fortea
- Department of Physiology and Biophysics, Weill Cornell Medical CollegeNew YorkUnited States
| | - Sangyun Lee
- Department of Anesthesiology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Jason D Galpin
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of MedicineIowa CityUnited States
| | - Malvin Vien
- Department of Anesthesiology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of MedicineIowa CityUnited States
| | - Alessio Accardi
- Department of Anesthesiology, Weill Cornell Medical CollegeNew YorkUnited States
- Department of Physiology and Biophysics, Weill Cornell Medical CollegeNew YorkUnited States
- Department of Biochemistry, Weill Cornell Medical CollegeNew YorkUnited States
| | - Simon Bernèche
- SIB Swiss Institute of Bioinformatics, University of BaselBaselSwitzerland
- Biozentrum, University of BaselBaselSwitzerland
| |
Collapse
|
7
|
Wojciechowski D, Kovalchuk E, Yu L, Tan H, Fahlke C, Stölting G, Alekov AK. Barttin Regulates the Subcellular Localization and Posttranslational Modification of Human Cl -/H + Antiporter ClC-5. Front Physiol 2018; 9:1490. [PMID: 30405442 PMCID: PMC6206076 DOI: 10.3389/fphys.2018.01490] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 10/02/2018] [Indexed: 01/17/2023] Open
Abstract
Dent disease 1 (DD1) is a renal salt-wasting tubulopathy associated with mutations in the Cl-/H+ antiporter ClC-5. The disease typically manifests with proteinuria, hypercalciuria, nephrocalcinosis, and nephrolithiasis but is characterized by large phenotypic variability of no clear origin. Several DD1 cases have been reported lately with additional atypical hypokalemic metabolic alkalosis and hyperaldosteronism, symptoms usually associated with another renal disease termed Bartter syndrome (BS). Expression of the Bartter-like DD1 mutant ClC-5 G261E in HEK293T cells showed that it is retained in the ER and lacks the complex glycosylation typical for ClC-5 WT. Accordingly, the mutant abolished CLC ionic transport. Such phenotype is not unusual and is often observed also in DD1 ClC-5 mutants not associated with Bartter like phenotype. We noticed, therefore, that one type of BS is associated with mutations in the protein barttin that serves as an accessory subunit regulating the function and subcellular localization of ClC-K channels. The overlapping symptomatology of DD1 and BS, together with the homology between the proteins of the CLC family, led us to investigate whether barttin might also regulate ClC-5 transport. In HEK293T cells, we found that barttin cotransfection impairs the complex glycosylation and arrests ClC-5 in the endoplasmic reticulum. As barttin and ClC-5 are both expressed in the thin and thick ascending limbs of the Henle's loop and the collecting duct, interactions between the two proteins could potentially contribute to the phenotypic variability of DD1. Pathologic barttin mutants differentially regulated trafficking and processing of ClC-5, suggesting that the interaction between the two proteins might be relevant also for the pathophysiology of BS. Our findings show that barttin regulates the subcellular localization not only of kidney ClC-K channels but also of the ClC-5 transporter, and suggest that ClC-5 might potentially play a role not only in kidney proximal tubules but also in tubular kidney segments expressing barttin. In addition, they demonstrate that the spectrum of clinical, genetic and molecular pathophysiology investigation of DD1 should be extended.
Collapse
Affiliation(s)
| | - Elena Kovalchuk
- Institute for Neurophysiology, Hannover Medical School, Hanover, Germany
| | - Lan Yu
- Institute for Neurophysiology, Hannover Medical School, Hanover, Germany
| | - Hua Tan
- Institute of Complex Systems 4 (ICS-4) – Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Christoph Fahlke
- Institute of Complex Systems 4 (ICS-4) – Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Gabriel Stölting
- Institute of Complex Systems 4 (ICS-4) – Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Alexi K. Alekov
- Institute for Neurophysiology, Hannover Medical School, Hanover, Germany
| |
Collapse
|
8
|
Rohrbough J, Nguyen H, Lamb FS. Modulation of ClC-3 gating and proton/anion exchange by internal and external protons and the anion selectivity filter. J Physiol 2018; 596:4091-4119. [PMID: 29917234 PMCID: PMC6117567 DOI: 10.1113/jp276332] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/07/2018] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS The ClC-3 2Cl- /1H+ exchanger modulates endosome pH and Cl- concentration. We investigated the relationships between ClC-3-mediated ion transport (steady-state transport current, ISS ), gating charge (Q) and cytoplasmic alkalization. ClC-3 transport is functionally unidirectional. ClC-5 and ClC-3 display indistinguishable exchange ratios, but ClC-3 cycling is less "efficient", as reflected by a large Q/ISS . An M531A mutation predicted to increase water-wire stability and cytoplasmic proton supply improves efficiency. Protonation (pH 5.0) of the outer glutamate gate (Gluext ; E224) reduces Q, inhibits transport, and weakens coupling. Removal of the central tyrosine anion gate (Y572S) greatly increases uncoupled anion current. Tyrosine -OH removal (Y572F) alters anion selectivity and impairs coupling. E224 and Y572 act as anion barriers, and contribute to gating. The Y572 side chain and -OH regulate Q movement kinetics and voltage dependence. E224 and Y572 interact to create a "closed" inner gate conformation that maintains coupling during cycling. ABSTRACT We utilized plasma membrane-localized ClC-3 to investigate relationships between steady-state transport current (ISS ), gating charge (Q) movement, and cytoplasmic alkalization rate. ClC-3 exhibited lower transport efficiency than ClC-5, as reflected by a larger Q/ISS ratio, but an indistinguishable Cl- /H+ coupling ratio. External SCN- reduced H+ transport rate and uncoupled anion/H+ exchange by 80-90%. Removal of the external gating glutamate ("Gluext ") (E224A mutation) reduced Q and abolished H+ transport. We hypothesized that Methionine 531 (M531) impedes "water wire" H+ transfer from the cytoplasm to E224. Accordingly, an M531A mutation decreased the Q/ISS ratio by 50% and enhanced H+ transport. External protons (pH 5.0) inhibited ISS and markedly reduced Q while shifting the Q-voltage (V) relationship positively. The Cl- /H+ coupling ratio at pH 5.0 was significantly increased, consistent with externally protonated Gluext adopting an outward/open position. Internal "anion gate" removal (Y572S) dramatically increased ISS and impaired coupling, without slowing H+ transport rate. Loss of both gates (Y572S/E224A) resulted in a large "open pore" conductance. Y572F (removing only the phenolic hydroxide) and Y572S shortened Q duration similarly, resulting in faster Q kinetics at all voltages. These data reveal a complex relationship between Q and ion transport. Q/ISS must be assessed together with coupling ratio to properly interpret efficiency. Coupling and transport rate are influenced by the anion, internal proton supply and external protons. Y572 regulates H+ coupling as well as anion selectivity, and interacts directly with E224. Disruption of this "closed gate" conformation by internal protons may represent a critical step in the ClC-3 transport cycle.
Collapse
Affiliation(s)
- Jeffrey Rohrbough
- Departments of Pediatrics and Molecular Physiology & BiophysicsMonroe Carell Children's Hospital at Vanderbilt UniversityNashvilleTNUSA
| | - Hong‐Ngan Nguyen
- Departments of Pediatrics and Molecular Physiology & BiophysicsMonroe Carell Children's Hospital at Vanderbilt UniversityNashvilleTNUSA
| | - Fred S. Lamb
- Departments of Pediatrics and Molecular Physiology & BiophysicsMonroe Carell Children's Hospital at Vanderbilt UniversityNashvilleTNUSA
| |
Collapse
|
9
|
Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
Collapse
Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| |
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
Ramdass A, Sathish V, Velayudham M, Thanasekaran P, Rajagopal S. Phosphorescence “Turn-On” Sensing of Anions by Rhenium(I) Schiff-Base Complexes. ChemistrySelect 2018. [DOI: 10.1002/slct.201702306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Arumugam Ramdass
- Research Department of Chemistry; Aditanar College of Arts and Science; Tiruchendur - 628 216 India
| | - Veerasamy Sathish
- Department of Chemistry; Bannari Amman Institute of Technology; Sathyamangalam - 638 401 India
| | - Murugesan Velayudham
- Department of Chemistry; Thiagarajar College of Engineering; Madurai - 625015 India
| | | | | |
Collapse
|
12
|
Zhang Y, Fang X, Xu H, Shen Q. Genetic Analysis of Dent's Disease and Functional Research of CLCN5 Mutations. DNA Cell Biol 2017; 36:1151-1158. [PMID: 29058463 DOI: 10.1089/dna.2017.3731] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Dent's disease is an X-linked inherited renal disease. Patients with Dent's disease often carry mutations in genes encoding the Cl-/H+ exchanger ClC-5 and/or inositol polyphosphate 5-phosphatase (OCRL1). However, the mutations involved and the biochemical effects of these mutations are not fully understood. To characterize genetic changes in Dent's disease patients, in this study, samples from nine Chinese patients were subjected to genetic analysis. Among the nine patients, six were classified as having Dent-1 disease, one had Dent-2 disease, and two could not be classified. Expression of ClC-5 carrying Dent's disease-associated mutations in HEK293 cells had varying effects: (1) no detectable expression of mutant protein; (2) retention of a truncated protein in the endoplasmic reticulum; or (3) diminished protein expression with normal distribution in early endosomes. Dent's disease patients showed genetic heterogeneity and over 20% of patients did not have CLCN5 or OCRL1 mutations, suggesting the existence of other genetic factors. Using next-generation sequencing, we identified possible modifier genes that have not been previously reported in Dent's disease patients. Heterozygous variants in CFTR, SCNN1A, and SCNN1B genes associated with cystic fibrosis (CF) or CF-like disease were detected in four of our nine patients. These results may form the basis for future characterization of Dent's disease and genetic counseling approaches.
Collapse
Affiliation(s)
- Ya Zhang
- 1 Department of Nephrology, Children's Hospital of Fudan University , Shanghai, China .,2 Shanghai Kidney Development and Pediatric Kidney Disease Research Center , Shanghai, China
| | - Xiaoyan Fang
- 1 Department of Nephrology, Children's Hospital of Fudan University , Shanghai, China .,2 Shanghai Kidney Development and Pediatric Kidney Disease Research Center , Shanghai, China
| | - Hong Xu
- 1 Department of Nephrology, Children's Hospital of Fudan University , Shanghai, China .,2 Shanghai Kidney Development and Pediatric Kidney Disease Research Center , Shanghai, China
| | - Qian Shen
- 1 Department of Nephrology, Children's Hospital of Fudan University , Shanghai, China .,2 Shanghai Kidney Development and Pediatric Kidney Disease Research Center , Shanghai, China
| |
Collapse
|
13
|
Poroca DR, Pelis RM, Chappe VM. ClC Channels and Transporters: Structure, Physiological Functions, and Implications in Human Chloride Channelopathies. Front Pharmacol 2017; 8:151. [PMID: 28386229 PMCID: PMC5362633 DOI: 10.3389/fphar.2017.00151] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/09/2017] [Indexed: 02/04/2023] Open
Abstract
The discovery of ClC proteins at the beginning of the 1990s was important for the development of the Cl- transport research field. ClCs form a large family of proteins that mediate voltage-dependent transport of Cl- ions across cell membranes. They are expressed in both plasma and intracellular membranes of cells from almost all living organisms. ClC proteins form transmembrane dimers, in which each monomer displays independent ion conductance. Eukaryotic members also possess a large cytoplasmic domain containing two CBS domains, which are involved in transport modulation. ClC proteins function as either Cl- channels or Cl-/H+ exchangers, although all ClC proteins share the same basic architecture. ClC channels have two gating mechanisms: a relatively well-studied fast gating mechanism, and a slow gating mechanism, which is poorly defined. ClCs are involved in a wide range of physiological processes, including regulation of resting membrane potential in skeletal muscle, facilitation of transepithelial Cl- reabsorption in kidneys, and control of pH and Cl- concentration in intracellular compartments through coupled Cl-/H+ exchange mechanisms. Several inherited diseases result from C1C gene mutations, including myotonia congenita, Bartter's syndrome (types 3 and 4), Dent's disease, osteopetrosis, retinal degeneration, and lysosomal storage diseases. This review summarizes general features, known or suspected, of ClC structure, gating and physiological functions. We also discuss biophysical properties of mammalian ClCs that are directly involved in the pathophysiology of several human inherited disorders, or that induce interesting phenotypes in animal models.
Collapse
Affiliation(s)
- Diogo R Poroca
- Department of Physiology and Biophysics, Dalhousie University, Halifax NS, Canada
| | - Ryan M Pelis
- Department of Pharmacology, Dalhousie University, Halifax NS, Canada
| | - Valérie M Chappe
- Department of Physiology and Biophysics, Dalhousie University, Halifax NS, Canada
| |
Collapse
|
14
|
Ruhe F, Olling A, Abromeit R, Rataj D, Grieschat M, Zeug A, Gerhard R, Alekov A. Overexpression of the Endosomal Anion/Proton Exchanger ClC-5 Increases Cell Susceptibility toward Clostridium difficile Toxins TcdA and TcdB. Front Cell Infect Microbiol 2017; 7:67. [PMID: 28348980 PMCID: PMC5346576 DOI: 10.3389/fcimb.2017.00067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 02/21/2017] [Indexed: 12/30/2022] Open
Abstract
Virulent C. difficile toxins TcdA and TcdB invade host intestinal epithelia by endocytosis and use the acidic environment of intracellular vesicles for further processing and activation. We investigated the role of ClC-5, a chloride/proton exchanger expressed in the endosomes of gastrointestinal epithelial cells, in the activation and processing of C. difficile toxins. Enhanced intoxication by TcdA and TcdB was observed in cells expressing ClC-5 but not ClC-4, another chloride/proton exchanger with similar function but different localization. In accordance with the established physiological function of ClC-5, its expression lowered the endosomal pH in HEK293T cells by approximately 0.6 units and enhanced approximately 5-fold the internalization of TcdA. In colon HT29 cells, 34% of internalized TcdA localized to ClC-5-containing vesicles defined by colocalization with Rab5, Rab4a, and Rab7 as early and early-to-late of endosomes but not as Rab11-containing recycling endosomes. Impairing the cellular uptake of TcdA by deleting the toxin CROPs domain did not abolish the effects of ClC-5. In addition, the transport-incompetent mutant ClC-5 E268Q similarly enhanced both endosomal acidification and intoxication by TcdA but facilitated the internalization of the toxin to a lower extent. These data suggest that ClC-5 enhances the cytotoxic action of C. difficile toxins by accelerating the acidification and maturation of vesicles of the early and early-to-late endosomal system. The dispensable role of electrogenic ion transport suggests that the voltage-dependent nonlinear capacitances of mammalian CLC transporters serve important physiological functions. Our data shed light on the intersection between the endocytotic cascade of host epithelial cells and the internalization pathway of the large virulence C. difficile toxins. Identifying ClC-5 as a potential specific host ion transporter hijacked by toxins produced by pathogenic bacteria widens the horizon of possibilities for novel therapies of life-threatening gastrointestinal infections.
Collapse
Affiliation(s)
- Frederike Ruhe
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Alexandra Olling
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | - Rasmus Abromeit
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Dennis Rataj
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | | | - Andre Zeug
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| | - Ralf Gerhard
- Institute for Toxicology, Hannover Medical SchoolHannover, Germany
| | - Alexi Alekov
- Institute for Neurophysiology, Hannover Medical SchoolHannover, Germany
| |
Collapse
|