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Yun Y, Park SS, Lee S, Seok H, Park S, Lee SY. Expanding Genotype-Phenotype Correlation of CLCNKA and CLCNKB Variants Linked to Hearing Loss. Int J Mol Sci 2023; 24:17077. [PMID: 38069401 PMCID: PMC10707517 DOI: 10.3390/ijms242317077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/26/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
The ClC-K channels CLCNKA and CLCNKB are crucial for the transepithelial transport processes required for sufficient urinary concentrations and sensory mechanoelectrical transduction in the cochlea. Loss-of-function alleles in these channels are associated with various clinical phenotypes, ranging from hypokalemic alkalosis to sensorineural hearing loss (SNHL) accompanied by severe renal conditions, i.e., Bartter's syndrome. Using a stepwise genetic approach encompassing whole-genome sequencing (WGS), we identified one family with compound heterozygous variants in the ClC-K channels, specifically a truncating variant in CLCNKA in trans with a contiguous deletion of CLCNKA and CLCNKB. Breakpoint PCR and Sanger sequencing elucidated the breakpoint junctions derived from WGS, and allele-specific droplet digital PCR confirmed one copy loss of the CLCNKA_CLCNKB contiguous deletion. The proband that harbors the CLCNKA_CLCNKB variants is characterized by SNHL without hypokalemic alkalosis and renal anomalies, suggesting a distinct phenotype in the ClC-K channels in whom SNHL predominantly occurs. These results expanded genotypes and phenotypes associated with ClC-K channels, including the disease entities associated with non-syndromic hearing loss. Repeated identification of deletions across various extents of CLCNKA_CLCNKB suggests a mutational hotspot allele, highlighting the need for an in-depth analysis of the CLCNKA_CLCNKB intergenic region, especially in undiagnosed SNHL patients with a single hit in CLCNKA.
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Affiliation(s)
- Yejin Yun
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Sang Soo Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Soyoung Lee
- GENOME INSIGHT TECHNOLOGY Inc., Daejeon 34051, Republic of Korea (S.P.)
| | - Heeyoung Seok
- Department of Transdisciplinary Research and Collaboration, Genomics Core Facility, Biomedical Research Institute, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Seongyeol Park
- GENOME INSIGHT TECHNOLOGY Inc., Daejeon 34051, Republic of Korea (S.P.)
| | - Sang-Yeon Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
- Department of Genomic Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
- Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul 03080, Republic of Korea
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2
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Murad H, Rafeeq M. Cheminformatics approach for identification of N-HyMenatPimeMelly as a novel potential ligand against RAS and renal chloride channel. J Biomol Struct Dyn 2023:1-15. [PMID: 37882351 DOI: 10.1080/07391102.2023.2273439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 10/14/2023] [Indexed: 10/27/2023]
Abstract
Some angiotensin receptor (AR) blockers interfere with the renal chloride channel (ClC-K), which plays an important role in urine concentration. Identifying ligands targeting this channel, whether activating or blocking, is highly desirable because it could open the way for interventions that modulate their activity. In this study, the Asinex (BioDesign) complete library was screened to identify a compound with favorable physicochemical and pharmacokinetic properties, which have both AR blocking and ClC-Ka-modulating activities to present it as a novel potential oral candidate which could be useful for treatment of salt-sensitive hypertension without major ClC-K affection. A compound, N-{[4-Hydroxy-1-(2-methyl-1,6-naphthyridin-4-yl)-4-piperidinyl]methyl}-N-methyl-L-lysinamide (N-HyMenatPimeMelly) (Chem Spider ID 68416221), was identified as a potent potential oral ligand of the renin-angiotensin system (RAS) and ClC-Ka with docking scores ranging from -10.978 to -7.324 with the four selected proteins (4YAY: AR type 1, 2PFI: Cytoplasmic domain of ClC-Ka, 6JOD: AR type 2 and 6M0J: Angiotensin-converting enzyme 2). The protein-ligand complex was used to perform molecular dynamics (MD) simulation for 100 ns. The QikProp and SwissADME tools' results showed that the compound has ADME/T and drug-likeness properties, which are within the permissible ranges for 95% of known drugs. The density functional theory (DFT) analysis and MD simulation extended the study toward computational validation. Throughout the study, N-HyMenatPimeMelly has shown good interactions and stable performance in MD simulation and DFT analysis. The whole analysis has produced promising results, and N-HyMenatPimeMelly can be treated as a novel potential RAS and ClC-K oral ligand, however, experimental validation is needed before human use.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Hussam Murad
- Department of Pharmacology, Faculty of Medicine, Rabigh Campus, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Misbahudin Rafeeq
- Department of Pharmacology, Faculty of Medicine, Rabigh Campus, King Abdulaziz University, Jeddah, Saudi Arabia
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3
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Coppola MA, Pusch M, Imbrici P, Liantonio A. Small Molecules Targeting Kidney ClC-K Chloride Channels: Applications in Rare Tubulopathies and Common Cardiovascular Diseases. Biomolecules 2023; 13:biom13040710. [PMID: 37189456 DOI: 10.3390/biom13040710] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/15/2023] [Accepted: 04/19/2023] [Indexed: 05/17/2023] Open
Abstract
Given the key role played by ClC-K chloride channels in kidney and inner ear physiology and pathology, they can be considered important targets for drug discovery. Indeed, ClC-Ka and ClC-Kb inhibition would interfere with the urine countercurrent concentration mechanism in Henle's loop, which is responsible for the reabsorption of water and electrolytes from the collecting duct, producing a diuretic and antihypertensive effect. On the other hand, ClC-K/barttin channel dysfunctions in Bartter Syndrome with or without deafness will require the pharmacological recovery of channel expression and/or activity. In these cases, a channel activator or chaperone would be appealing. Starting from a brief description of the physio-pathological role of ClC-K channels in renal function, this review aims to provide an overview of the recent progress in the discovery of ClC-K channel modulators.
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Affiliation(s)
| | - Michael Pusch
- Institute of Biophysics, National Research Council, 16149 Genova, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", 70125 Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", 70125 Bari, Italy
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4
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Ye S, Wu P, Gao Z, Wang M, Zhou L, Qi Z. Inhibitory effect of S-nitroso-N-acetylpenicillamine on the basolateral 10-pS Cl- channel in thick ascending limb. PLoS One 2023; 18:e0284707. [PMID: 37083928 PMCID: PMC10121052 DOI: 10.1371/journal.pone.0284707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 04/05/2023] [Indexed: 04/22/2023] Open
Abstract
We have previously reported that L-arginine, a nitric oxide synthase substrate, inhibits the basolateral 10-pS Cl- channel through the cGMP/PKG signaling pathway in the thick ascending limb (TAL). As a NO releasing agent, the effect of S-nitroso-N-acetyl-penicillamine (SNAP) on the channel activity was examined in thick ascending limb of C57BL/6 mice in the present study. SNAP inhibited the basolateral 10-pS Cl- channel in a dose-dependent manner with an IC50 value of 6.6 μM. The inhibitory effect of SNAP was abolished not only by NO scavenger (carboxy-PTIO) but also by blockers of soluble guanylate cyclase (ODQ or LY-83583), indicating that the cGMP-dependent signaling pathway is involved. Moreover, the inhibitory effect of SNAP on the channel was strongly attenuated by a protein kinase G (PKG)-specific inhibitor, KT-5823, but not by the PDE2 inhibitor, BAY-60-7550. We concluded that SNAP inhibited the basolateral 10-pS Cl- channels in the TAL through a cGMP/PKG signaling pathway. As the 10-pS Cl- channel is important for regulation of NaCl absorption along the nephron, these data suggest that SNAP might be served as a regulator to prevent high-salt absorption related diseases, such as hypertension.
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Affiliation(s)
- Shiwei Ye
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
| | - Peng Wu
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zhongxiuzi Gao
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Mingyan Wang
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
| | - Li Zhou
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
| | - Zhi Qi
- Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen, China
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5
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Andreassen SN, Toft-Bertelsen TL, Wardman JH, Villadsen R, MacAulay N. Transcriptional profiling of transport mechanisms and regulatory pathways in rat choroid plexus. Fluids Barriers CNS 2022; 19:44. [PMID: 35659263 PMCID: PMC9166438 DOI: 10.1186/s12987-022-00335-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 05/02/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Dysregulation of brain fluid homeostasis associates with brain pathologies in which fluid accumulation leads to elevated intracranial pressure. Surgical intervention remains standard care, since specific and efficient pharmacological treatment options are limited for pathologies with disturbed brain fluid homeostasis. Such lack of therapeutic targets originates, in part, from the incomplete map of the molecular mechanisms underlying cerebrospinal fluid (CSF) secretion by the choroid plexus. METHODS The transcriptomic profile of rat choroid plexus was generated by RNA Sequencing (RNAseq) of whole tissue and epithelial cells captured by fluorescence-activated cell sorting (FACS), and compared to proximal tubules. The bioinformatic analysis comprised mapping to reference genome followed by filtering for type, location, and association with alias and protein function. The transporters and associated regulatory modules were arranged in discovery tables according to their transcriptional abundance and tied together in association network analysis. RESULTS The transcriptomic profile of choroid plexus displays high similarity between sex and species (human, rat, and mouse) and lesser similarity to another high-capacity fluid-transporting epithelium, the proximal tubules. The discovery tables provide lists of transport mechanisms that could participate in CSF secretion and suggest regulatory candidates. CONCLUSIONS With quantification of the transport protein transcript abundance in choroid plexus and their potentially linked regulatory modules, we envision a molecular tool to devise rational hypotheses regarding future delineation of choroidal transport proteins involved in CSF secretion and their regulation. Our vision is to obtain future pharmaceutical targets towards modulation of CSF production in pathologies involving disturbed brain water dynamics.
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Affiliation(s)
- Søren N Andreassen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Trine L Toft-Bertelsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Jonathan H Wardman
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - René Villadsen
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark.
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6
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Vargas-Poussou R. Pathophysiological aspects of the thick ascending limb and novel genetic defects: HELIX syndrome and transient antenatal Bartter syndrome. Pediatr Nephrol 2022; 37:239-252. [PMID: 33733301 DOI: 10.1007/s00467-021-05019-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/29/2021] [Accepted: 02/17/2021] [Indexed: 10/21/2022]
Abstract
The thick ascending limb plays a central role in human kidney physiology, participating in sodium reabsorption, urine concentrating mechanisms, calcium and magnesium homeostasis, bicarbonate and ammonium homeostasis, and uromodulin synthesis. This review aims to illustrate the importance of these roles from a pathophysiological point of view by describing the interactions of the key proteins of this segment and by discussing how recently identified and long-known hereditary diseases affect this segment. The descriptions of two recently described salt-losing tubulopathies, transient antenatal Bartter syndrome and HELIX syndrome, which are caused by mutations in MAGED2 and CLDN10 genes, respectively, highlight the role of new players in the modulation of sodium reabsorption the thick ascending limb.
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Affiliation(s)
- Rosa Vargas-Poussou
- Department of Molecular Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, 20-40 rue Leblanc, 75015, Paris, France. .,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France. .,Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.
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7
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Wu X, Yang G, Chen S, Tang M, Jian S, Chen F, Wu X. Bartter syndrome with long-term follow-up: a case report. J Int Med Res 2020; 48:300060520947876. [PMID: 32857947 PMCID: PMC7705384 DOI: 10.1177/0300060520947876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Bartter syndrome is a rare inherited disease caused by CLCNKB mutation, which results in inactivation of the chloride channel Kb protein. Bartter syndrome is characterized by extreme hypokalemia, hypochloremia, metabolic alkalosis, hyperrenin-induced angiotensinemia, hyperaldosteronemia, and normal blood pressure. We herein report a case of Bartter syndrome that manifested as vomiting, hypokalemia, metabolic alkalosis, normal blood pressure, and significant hyperrenin-induced angiotensinemia. The patient, a 5-month-old girl, carried two known heterozygous pathogenic mutations: c.88C > T (p.Arg30*), which she had inherited from her father, and c.1313G > A (p.Arg438His), which she had inherited from her mother. Treatment with indomethacin, a nonsteroidal anti-inflammatory drug, led to rapid improvement of the hypokalemia, and treatment was continued for 14 years. The indomethacin also induced a sustainable reduction in the hypokalemia and metabolic alkalosis.
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Affiliation(s)
- Xueling Wu
- Department of Respiratory Medicine, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Gang Yang
- Department of Cardiology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing, Sichuan, China
| | - Shiyu Chen
- Key Laboratory of Diagnostic Medicine designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, Sichuan, China
| | - Min Tang
- Key Laboratory of Diagnostic Medicine designated by the Chinese Ministry of Education, Chongqing Medical University, Chongqing, Sichuan, China
| | - Shan Jian
- Department of Paediatrics, Peking Union Medical College Hospital, Beijing, China
| | - Fuhui Chen
- Department of Respiratory, the Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - Xiulin Wu
- Department of Geriatrics, Southwest Hospital, Military Medical University, Chongqing, China
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8
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Sahbani D, Strumbo B, Tedeschi S, Conte E, Camerino GM, Benetti E, Montini G, Aceto G, Procino G, Imbrici P, Liantonio A. Functional Study of Novel Bartter's Syndrome Mutations in ClC-Kb and Rescue by the Accessory Subunit Barttin Toward Personalized Medicine. Front Pharmacol 2020; 11:327. [PMID: 32256370 PMCID: PMC7092721 DOI: 10.3389/fphar.2020.00327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 03/05/2020] [Indexed: 12/12/2022] Open
Abstract
Type III and IV Bartter syndromes (BS) are rare kidney tubulopathies caused by loss-of-function mutations in the CLCNKB and BSND genes coding respectively for the ClC-Kb chloride channels and accessory subunit barttin. ClC-K channels are expressed in the Henle's loop, distal convoluted tubule, and cortical collecting ducts of the kidney and contribute to chloride absorption and urine concentration. In our Italian cohort, we identified two new mutations in CLCNKB, G167V and G289R, in children affected by BS and previously reported genetic variants, A242E, a chimeric gene and the deletion of the whole CLCNKB. All the patients had hypokalemia and metabolic alkalosis, increased serum renin and aldosterone levels and were treated with a symptomatic therapy. In order to define the molecular mechanisms responsible for BS, we co-expressed ClC-Kb wild type and channels with point mutations with barttin in HEK 293 cells and characterized chloride currents through the patch-clamp technique. In addition, we attempted to revert the functional defect caused by BS mutations through barttin overexpression. G167V and A242E channels showed a drastic current reduction compared to wild type, likely suggesting compromised expression of mutant channels at the plasma membrane. Conversely, G289R channel was similar to wild type raising the doubt that an additional mutation in another gene or other mechanisms could account for the clinical phenotype. Interestingly, increasing ClC-K/barttin ratio augmented G167V and A242E mutants' chloride current amplitudes towards wild type levels. These results confirm a genotype-phenotype correlation in BS and represent a preliminary proof of concept that molecules functioning as molecular chaperones can restore channel function in expression-defective ClC-Kb mutants.
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Affiliation(s)
- Dalila Sahbani
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Bice Strumbo
- Laboratory of Medical Genetics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Silvana Tedeschi
- Laboratory of Medical Genetics, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | | | - Elisa Benetti
- Nephrology, Dialysis and Transplant Unit, Department of Women's and Children's Health, University-Hospital of Padova, Padova, Italy
| | - Giovanni Montini
- Pediatric Nephrology, Dialysis, and Transplant Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | | | - Giuseppe Procino
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
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Gorinski N, Wojciechowski D, Guseva D, Abdel Galil D, Mueller FE, Wirth A, Thiemann S, Zeug A, Schmidt S, Zareba-Kozioł M, Wlodarczyk J, Skryabin BV, Glage S, Fischer M, Al-Samir S, Kerkenberg N, Hohoff C, Zhang W, Endeward V, Ponimaskin E. DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels. J Biol Chem 2020; 295:5970-5983. [PMID: 32184353 DOI: 10.1074/jbc.ra119.011049] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 03/13/2020] [Indexed: 12/21/2022] Open
Abstract
Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7 -/- mice. Although palmitoylation of barttin in kidneys of Zdhhc7 -/- animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7 -/- mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.
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Affiliation(s)
- Nataliya Gorinski
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | | | - Daria Guseva
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Dalia Abdel Galil
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Franziska E Mueller
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Alexander Wirth
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Stefan Thiemann
- Institute for Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Silke Schmidt
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Monika Zareba-Kozioł
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Jakub Wlodarczyk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Boris V Skryabin
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, 48149 Münster, Germany
| | - Silke Glage
- Institute for Laboratory Animal Science, Hannover Medical School, 30625 Hannover, Germany
| | - Martin Fischer
- Institute for Neurophysiology, Hannover Medical School, 30625 Hannover, Germany
| | - Samer Al-Samir
- Institute of Vegetative Physiology, Hannover Medical School, 30625 Hannover, Germany
| | - Nicole Kerkenberg
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, 48149 Münster, Germany
| | - Christa Hohoff
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany
| | - Weiqi Zhang
- Department of Psychiatry and Psychotherapy, Laboratory for Molecular Psychiatry, University of Münster, 48149 Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, 48149 Münster, Germany
| | - Volker Endeward
- Institute of Vegetative Physiology, Hannover Medical School, 30625 Hannover, Germany
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany.
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10
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Bignon Y, Sakhi I, Bitam S, Bakouh N, Keck M, Frachon N, Paulais M, Planelles G, Teulon J, Andrini O. Analysis of CLCNKB mutations at dimer-interface, calcium-binding site, and pore reveals a variety of functional alterations in ClC-Kb channel leading to Bartter syndrome. Hum Mutat 2019; 41:774-785. [PMID: 31803959 DOI: 10.1002/humu.23962] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/14/2019] [Accepted: 11/29/2019] [Indexed: 12/12/2022]
Abstract
Pathological missense mutations in CLCNKB gene give a wide spectrum of clinical phenotypes in Bartter syndrome type III patients. Molecular analysis of the mutated ClC-Kb channels can be helpful to classify the mutations according to their functional alteration. We investigated the functional consequences of nine mutations in the CLCNKB gene causing Bartter syndrome. We first established that all tested mutations lead to decreased ClC-Kb currents. Combining electrophysiological and biochemical methods in Xenopus laevis oocytes and in MDCKII cells, we identified three classes of mutations. One class is characterized by altered channel trafficking. p.A210V, p.P216L, p.G424R, and p.G437R are totally or partially retained in the endoplasmic reticulum. p.S218N is characterized by reduced channel insertion at the plasma membrane and altered pH-sensitivity; thus, it falls in the second class of mutations. Finally, we found a novel class of functionally inactivated mutants normally present at the plasma membrane. Indeed, we found that p.A204T alters the pH-sensitivity, p.A254V abolishes the calcium-sensitivity. p.G219C and p.G465R are probably partially inactive at the plasma membrane. In conclusion, most pathogenic mutants accumulate partly or totally in intracellular compartments, but some mutants are normally present at the membrane surface and simultaneously show a large range of altered channel gating properties.
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Affiliation(s)
- Yohan Bignon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Imene Sakhi
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Sara Bitam
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Naziha Bakouh
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Mathilde Keck
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | | | - Marc Paulais
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Gabrielle Planelles
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Jacques Teulon
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Laboratoire Physiologie Rénale et Tubulopathies, Paris, France.,CNRS ERL8228, Paris, France
| | - Olga Andrini
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, Lyon, France
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11
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Viennet T, Bungert-Plümke S, Elter S, Viegas A, Fahlke C, Etzkorn M. Reconstitution and NMR Characterization of the Ion-Channel Accessory Subunit Barttin in Detergents and Lipid-Bilayer Nanodiscs. Front Mol Biosci 2019; 6:13. [PMID: 30931313 PMCID: PMC6427064 DOI: 10.3389/fmolb.2019.00013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/19/2019] [Indexed: 01/21/2023] Open
Abstract
Barttin is an accessory subunit of ClC-K chloride channels expressed in the kidney and the inner ear. Main functions of ClC-K/barttin channels are the generation of the cortico-medullary osmotic gradients in the kidney and the endocochlear potential in the inner ear. Mutations in the gene encoding barttin, BSND, result in impaired urinary concentration and sensory deafness. Barttin is predicted to be a two helical integral membrane protein that directly interacts with its ion channel in the membrane bilayer where it stabilizes the channel complex, promotes its incorporation into the surface membrane and leads to channel activation. It therefore is an attractive target to address fundamental questions of intermolecular communication within the membrane. However, so far inherent challenges in protein expression and stabilization prevented comprehensive in vitro studies and structural characterization. Here we demonstrate that cell-free expression enables production of sufficient quantities of an isotope-labeled barttin variant (I72X Barttin, capable to promote surface membrane insertion and channel activation) for NMR-based structural studies. Additionally, we established purification protocols as well as reconstitution strategies in detergent micelles and phospholipid bilayer nanodiscs. Stability, folding, and NMR data quality are reported as well as a suitable assignment strategy, paving the way to its structural characterization.
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Affiliation(s)
- Thibault Viennet
- Institute of Physical Biology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Institute of Complex Systems 6, Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, Jülich, Germany
| | - Stefanie Bungert-Plümke
- Institute of Complex Systems 4, Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, Jülich, Germany
| | - Shantha Elter
- Institute of Physical Biology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Aldino Viegas
- Institute of Physical Biology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Christoph Fahlke
- Institute of Complex Systems 4, Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, Jülich, Germany
| | - Manuel Etzkorn
- Institute of Physical Biology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Institute of Complex Systems 6, Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, Jülich, Germany
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12
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Gonzalez-Vicente A, Saez F, Monzon CM, Asirwatham J, Garvin JL. Thick Ascending Limb Sodium Transport in the Pathogenesis of Hypertension. Physiol Rev 2019; 99:235-309. [PMID: 30354966 DOI: 10.1152/physrev.00055.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The thick ascending limb plays a key role in maintaining water and electrolyte balance. The importance of this segment in regulating blood pressure is evidenced by the effect of loop diuretics or local genetic defects on this parameter. Hormones and factors produced by thick ascending limbs have both autocrine and paracrine effects, which can extend prohypertensive signaling to other structures of the nephron. In this review, we discuss the role of the thick ascending limb in the development of hypertension, not as a sole participant, but one that works within the rich biological context of the renal medulla. We first provide an overview of the basic physiology of the segment and the anatomical considerations necessary to understand its relationship with other renal structures. We explore the physiopathological changes in thick ascending limbs occurring in both genetic and induced animal models of hypertension. We then discuss the racial differences and genetic defects that affect blood pressure in humans through changes in thick ascending limb transport rates. Throughout the text, we scrutinize methodologies and discuss the limitations of research techniques that, when overlooked, can lead investigators to make erroneous conclusions. Thus, in addition to advancing an understanding of the basic mechanisms of physiology, the ultimate goal of this work is to understand our research tools, to make better use of them, and to contextualize research data. Future advances in renal hypertension research will require not only collection of new experimental data, but also integration of our current knowledge.
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Affiliation(s)
| | - Fara Saez
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Casandra M Monzon
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Jessica Asirwatham
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Jeffrey L Garvin
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
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13
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Lagostena L, Zifarelli G, Picollo A. New Insights into the Mechanism of NO 3 - Selectivity in the Human Kidney Chloride Channel ClC-Ka and the CLC Protein Family. J Am Soc Nephrol 2019; 30:293-302. [PMID: 30635372 DOI: 10.1681/asn.2018060593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 12/01/2018] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The mechanism of anion selectivity in the human kidney chloride channels ClC-Ka and ClC-Kb is unknown. However, it has been thought to be very similar to that of other channels and antiporters of the CLC protein family, and to rely on anions interacting with a conserved Ser residue (Sercen) at the center of three anion binding sites in the permeation pathway Scen. In both CLC channels and antiporters, mutations of Sercen alter the anion selectivity. Structurally, the side chain of Sercen of CLC channels and antiporters typically projects into the pore and coordinates the anion bound at Scen. METHODS To investigate the role of several residues in anion selectivity of ClC-Ka, we created mutations that resulted in amino acid substitutions in these residues. We also used electrophysiologic techniques to assess the properties of the mutants. RESULTS Mutations in ClC-Ka that change Sercen to Gly, Pro, or Thr have only minor effects on anion selectivity, whereas the mutations in residues Y425A, F519A, and Y520A increase the NO3 -/Cl- permeability ratio, with Y425A having a particularly strong effect. CONCLUSION s ClC-Ka's mechanism of anion selectivity is largely independent of Sercen, and it is therefore unique in the CLC protein family. We identified the residue Y425 in ClC-Ka-and the corresponding residue (A417) in the chloride channel ClC-0-as residues that contribute to NO3 - discrimination in these channels. This work provides important and timely insight into the relationship between structure and function for the kidney chloride channels ClC-Ka and ClC-Kb, and for CLC proteins in general.
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Affiliation(s)
- Laura Lagostena
- Dulbecco Telethon Laboratory, Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy; and
| | - Giovanni Zifarelli
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Alessandra Picollo
- Dulbecco Telethon Laboratory, Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy; and
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14
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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Abstract
Bartter syndrome is an inherited renal tubular disorder caused by a defective salt reabsorption in the thick ascending limb of loop of Henle, resulting in salt wasting, hypokalemia, and metabolic alkalosis. Mutations of several genes encoding the transporters and channels involved in salt reabsorption in the thick ascending limb cause different types of Bartter syndrome. A poor phenotype-genotype relationship due to the interaction with other cotransporters and different degrees of compensation through alternative pathways is currently reported. However, phenotypic identification still remains the first step to guide the suspicion of Bartter syndrome. Given the rarity of the syndrome, and the lack of genetic characterization in most cases, limited clinical evidence for treatment is available and the therapy is based mainly on the comprehension of renal physiology and relies on the physician's personal experiences. A better understanding of the mutated channels and transporters could possibly generate targets for specific treatment in the future, also encompassing drugs aiming to correct deficiencies in folding or plasma membrane expression of the mutated proteins.
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Affiliation(s)
- Tamara da Silva Cunha
- Nephrology Division, Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina, São Paulo, Brazil,
| | - Ita Pfeferman Heilberg
- Nephrology Division, Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina, São Paulo, Brazil,
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16
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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.
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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
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17
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Kurtz I. Renal Tubular Acidosis: H +/Base and Ammonia Transport Abnormalities and Clinical Syndromes. Adv Chronic Kidney Dis 2018; 25:334-350. [PMID: 30139460 PMCID: PMC6128697 DOI: 10.1053/j.ackd.2018.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Renal tubular acidosis (RTA) represents a group of diseases characterized by (1) a normal anion gap metabolic acidosis; (2) abnormalities in renal HCO3- absorption or new renal HCO3- generation; (3) changes in renal NH4+, Ca2+, K+, and H2O homeostasis; and (4) extrarenal manifestations that provide etiologic diagnostic clues. The focus of this review is to give a general overview of the pathogenesis of the various clinical syndromes causing RTA with a particular emphasis on type I (hypokalemic distal RTA) and type II (proximal) RTA while reviewing their pathogenesis from a physiological "bottom-up" approach. In addition, the factors involved in the generation of metabolic acidosis in both type I and II RTA are reviewed highlighting the importance of altered renal ammonia production/partitioning and new HCO3- generation. Our understanding of the underlying tubular transport and extrarenal abnormalities has significantly improved since the first recognition of RTA as a clinical entity because of significant advances in clinical acid-base chemistry, whole tubule and single-cell H+/base transport, and the molecular characterization of the various transporters and channels that are functionally affected in patients with RTA. Despite these advances, additional studies are needed to address the underlying mechanisms involved in hypokalemia, altered ammonia production/partitioning, hypercalciuria, nephrocalcinosis, cystic abnormalities, and CKD progression in these patients.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, and Brain Research Institute, UCLA, Los Angeles, CA.
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18
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Wojciechowski D, Thiemann S, Schaal C, Rahtz A, de la Roche J, Begemann B, Becher T, Fischer M. Activation of renal ClC-K chloride channels depends on an intact N terminus of their accessory subunit barttin. J Biol Chem 2018; 293:8626-8637. [PMID: 29674316 DOI: 10.1074/jbc.ra117.000860] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 04/17/2018] [Indexed: 12/27/2022] Open
Abstract
ClC-K channels belong to the CLC family of chloride channels and chloride/proton antiporters. They contribute to sodium chloride reabsorption in Henle's loop of the kidney and to potassium secretion into the endolymph by the stria vascularis of the inner ear. Their accessory subunit barttin stabilizes the ClC-K/barttin complex, promotes its insertion into the surface membrane, and turns the pore-forming subunits into a conductive state. Barttin mutations cause Bartter syndrome type IV, a salt-wasting nephropathy with sensorineural deafness. Here, studying ClC-K/barttin channels heterologously expressed in MDCK-II and HEK293T cells with confocal imaging and patch-clamp recordings, we demonstrate that the eight-amino-acids-long barttin N terminus is required for channel trafficking and activation. Deletion of the complete N terminus (Δ2-8 barttin) retained barttin and human hClC-Ka channels in intracellular compartments. Partial N-terminal deletions did not compromise subcellular hClC-Ka trafficking but drastically reduced current amplitudes. Sequence deletions encompassing Thr-6, Phe-7, or Arg-8 in barttin completely failed to activate hClC-Ka. Analyses of protein expression and whole-cell current noise revealed that inactive channels reside in the plasma membrane. Substituting the deleted N terminus with a polyalanine sequence was insufficient for recovering chloride currents, and single amino acid substitutions highlighted that the correct sequence is required for proper function. Fast and slow gate activation curves obtained from rat V166E rClC-K1/barttin channels indicated that mutant barttin fails to constitutively open the slow gate. Increasing expression of barttin over that of ClC-K partially recovered this insufficiency, indicating that N-terminal modifications of barttin alter both binding affinities and gating properties.
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Affiliation(s)
- Daniel Wojciechowski
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Stefan Thiemann
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Christina Schaal
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Alina Rahtz
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Jeanne de la Roche
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Birgit Begemann
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Toni Becher
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Martin Fischer
- From the Institute for Neurophysiology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
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19
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Imbrici P, Nicolotti O, Leonetti F, Conte D, Liantonio A. Ion Channels in Drug Discovery and Safety Pharmacology. Methods Mol Biol 2018; 1800:313-326. [PMID: 29934900 DOI: 10.1007/978-1-4939-7899-1_15] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ion channels are membrane proteins involved in almost all physiological processes, including neurotransmission, muscle contraction, pace-making activity, secretion, electrolyte and water balance, immune response, and cell proliferation. Due to their broad distribution in human body and physiological roles, ion channels are attractive targets for drug discovery and safety pharmacology. Over the years ion channels have been associated to many genetic diseases ("channelopathies"). For most of these diseases the therapy is mainly empirical and symptomatic, often limited by lack of efficacy and tolerability for a number of patients. The search for the development of new and more specific therapeutic approaches is therefore strongly pursued. At the same time acquired channelopathies or dangerous side effects (such as proarrhythmic risk) can develop as a consequence of drugs unexpectedly targeting ion channels. Several noncardiovascular drugs are known to block cardiac ion channels, leading to potentially fatal delayed ventricular repolarization. Thus, the search of reliable preclinical cardiac safety testing in early stage of drug discovery is mandatory. To fulfill these needs, both ion channels drug discovery and toxicology strategies are evolving toward comprehensive research approaches integrating ad hoc designed in silico predictions and experimental studies for a more reliable and quick translation of results to the clinic side.Here we discuss two examples of how the combination of in silico methods and patch clamp experiments can help addressing drug discovery and safety issues regarding ion channels.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro", Bari, Italy.
| | - Orazio Nicolotti
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, Bari, Italy
| | - Francesco Leonetti
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Diana Conte
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
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20
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Pinelli L, Nissant A, Edwards A, Lourdel S, Teulon J, Paulais M. Dual regulation of the native ClC-K2 chloride channel in the distal nephron by voltage and pH. J Gen Physiol 2017; 148:213-26. [PMID: 27574292 PMCID: PMC5004338 DOI: 10.1085/jgp.201611623] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/07/2016] [Indexed: 12/23/2022] Open
Abstract
ClC-K2 is present on the basolateral membrane of kidney epithelial cells, but little is known about its single channel properties. Pinelli et al. record unitary ClC-K2 currents from intercalated cells of mouse connecting tubules and investigate their regulation by voltage, pH, Cl−, and Ca2+. ClC-K2, a member of the ClC family of Cl− channels and transporters, forms the major basolateral Cl− conductance in distal nephron epithelial cells and therefore plays a central role in renal Cl− absorption. However, its regulation remains largely unknown because of the fact that recombinant ClC-K2 has not yet been studied at the single-channel level. In the present study, we investigate the effects of voltage, pH, Cl−, and Ca2+ on native ClC-K2 in the basolateral membrane of intercalated cells from the mouse connecting tubule. The ∼10-pS channel shows a steep voltage dependence such that channel activity increases with membrane depolarization. Intracellular pH (pHi) and extracellular pH (pHo) differentially modulate the voltage dependence curve: alkaline pHi flattens the curve by causing an increase in activity at negative voltages, whereas alkaline pHo shifts the curve toward negative voltages. In addition, pHi, pHo, and extracellular Ca2+ strongly increase activity, mainly because of an increase in the number of active channels with a comparatively minor effect on channel open probability. Furthermore, voltage alters both the number of active channels and their open probability, whereas intracellular Cl− has little influence. We propose that changes in the number of active channels correspond to them entering or leaving an inactivated state, whereas modulation of open probability corresponds to common gating by these channels. We suggest that pH, through the combined effects of pHi and pHo on ClC-K2, might be a key regulator of NaCl absorption and Cl−/HCO3− exchange in type B intercalated cells.
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Affiliation(s)
- Laurent Pinelli
- Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, F-75006 Paris, France
| | - Antoine Nissant
- Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, F-75006 Paris, France
| | - Aurélie Edwards
- Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, F-75006 Paris, France
| | - Stéphane Lourdel
- Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, F-75006 Paris, France
| | - Jacques Teulon
- Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, F-75006 Paris, France
| | - Marc Paulais
- Sorbonne Universités, Université Pierre-et-Marie-Curie Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006 Paris, France Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, F-75006 Paris, France
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21
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Louet M, Bitam S, Bakouh N, Bignon Y, Planelles G, Lagorce D, Miteva MA, Eladari D, Teulon J, Villoutreix BO. In silico model of the human ClC-Kb chloride channel: pore mapping, biostructural pathology and drug screening. Sci Rep 2017; 7:7249. [PMID: 28775266 PMCID: PMC5543074 DOI: 10.1038/s41598-017-07794-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 06/29/2017] [Indexed: 12/16/2022] Open
Abstract
The human ClC-Kb channel plays a key role in exporting chloride ions from the cytosol and is known to be involved in Bartter syndrome type 3 when its permeation capacity is decreased. The ClC-Kb channel has been recently proposed as a potential therapeutic target to treat hypertension. In order to gain new insights into the sequence-structure-function relationships of this channel, to investigate possible impacts of amino-acid substitutions, and to design novel inhibitors, we first built a structural model of the human ClC-Kb channel using comparative modeling strategies. We combined in silico and in vitro techniques to analyze amino acids involved in the chloride ion pathway as well as to rationalize the possible role of several clinically observed mutations leading to the Bartter syndrome type 3. Virtual screening and drug repositioning computations were then carried out. We identified six novel molecules, including 2 approved drugs, diflusinal and loperamide, with Kd values in the low micromolar range, that block the human ClC-Kb channel and that could be used as starting point to design novel chemical probes for this potential therapeutic target.
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Affiliation(s)
- Maxime Louet
- INSERM, UMR_S 973, Université Paris Diderot, 39 rue Hélène Brion, 75013, Paris, France
| | - Sara Bitam
- Sorbonne Universités, UPMC Université Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Naziha Bakouh
- Sorbonne Universités, UPMC Université Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Yohan Bignon
- Sorbonne Universités, UPMC Université Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Gabrielle Planelles
- Sorbonne Universités, UPMC Université Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - David Lagorce
- INSERM, UMR_S 973, Université Paris Diderot, 39 rue Hélène Brion, 75013, Paris, France
| | - Maria A Miteva
- INSERM, UMR_S 973, Université Paris Diderot, 39 rue Hélène Brion, 75013, Paris, France
| | - Dominique Eladari
- Service d'Explorations Fonctionnelles Rénales, Hôpital Felix Guyon, CHU de la Réunion, St Denis F-97400, Ile de la Réunion, France et Inserm U1188, Diabète athérothrombose Thérapies Réunion Océan Indien (DéTROI). Université de La Réunion; CYROI, 2, rue Maxime Rivière, Sainte Clotilde, La Réunion, 97490, France
| | - Jacques Teulon
- Sorbonne Universités, UPMC Université Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, F-75006, Paris, France
| | - Bruno O Villoutreix
- INSERM, UMR_S 973, Université Paris Diderot, 39 rue Hélène Brion, 75013, Paris, France.
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22
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Cheng CJ, Lo YF, Chen JC, Huang CL, Lin SH. Functional severity of CLCNKB mutations correlates with phenotypes in patients with classic Bartter's syndrome. J Physiol 2017; 595:5573-5586. [PMID: 28555925 PMCID: PMC5556149 DOI: 10.1113/jp274344] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 05/08/2017] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS The highly variable phenotypes observed in patients with classic Bartter's syndrome (BS) remain unsatisfactorily explained. The wide spectrum of functional severity of CLCNKB mutations may contribute to the phenotypic variability, and the genotype-phenotype association has not been established. Low-level expression of the human ClC-Kb channel in mammalian cells impedes the functional study of CLCNKB mutations, and the underlying cause is still unclear. The human ClC-Kb channel is highly degraded by proteasome in human embryonic kidney cells. The C-terminal in-frame green fluorescent protein fusion may slow down the proteasome-mediated proteolysis. Barttin co-expression necessarily improves the stability, membrane trafficking and gating of ClC-Kb. CLCNKB mutations in barttin-binding sites, dimer interface or selectivity filter often have severe functional consequences. The remaining chloride conductance of the ClC-Kb mutant channel significantly correlates with the phenotypes, such as age at diagnosis, plasma chloride concentration, and the degree of calciuria in patients with classic BS. ABSTRACT Mutations in the CLCNKB gene encoding the human voltage-gated chloride ClC-Kb (hClC-Kb) channel cause classic Bartter's syndrome (BS). In contrast to antenatal BS, classic BS manifests with highly variable phenotypes. The functional severity of the mutant channel has been proposed to explain this phenomenon. Due to difficulties in the expression of hClC-Kb in heterologous expression systems, the functional consequences of mutant channels have not been thoroughly examined, and the genotype-phenotype association has not been established. In this study, we found that hClC-Kb, when expressed in human embryonic kidney (HEK) cells, was unstable due to degradation by proteasome. In-frame fusion of green fluorescent protein (GFP) to the C-terminus of the channel may ameliorate proteasome degradation. Co-expression of barttin increased protein abundance and membrane trafficking of hClC-Kb and markedly increased functional chloride current. We then functionally characterized 18 missense mutations identified in our classic BS cohort and others using HEK cells expressing hClC-Kb-GFP. Most CLCNKB mutations resulted in marked reduction in protein abundance and chloride current, especially those residing at barttin binding sites, dimer interface and selectivity filter. We enrolled classic BS patients carrying homozygous missense mutations with well-described functional consequences and clinical presentations for genotype-phenotype analysis. We found significant correlations of mutant chloride current with the age at diagnosis, plasma chloride concentration and urine calcium excretion rate. In conclusion, hClC-Kb expression in HEK cells is susceptible to proteasome degradation, and fusion of GFP to the C-terminus of hClC-Kb improves protein expression. The functional severity of the CLCNKB mutation is an important determinant of the phenotype in classic BS.
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Affiliation(s)
- Chih-Jen Cheng
- Department of Medicine, Division of Nephrology, Tri-Service General Hospital, National Defense Medical Center, Taipei, 114, Taiwan
| | - Yi-Fen Lo
- Department of Medicine, Division of Nephrology, Tri-Service General Hospital, National Defense Medical Center, Taipei, 114, Taiwan
| | - Jen-Chi Chen
- Department of Medicine, Division of Nephrology, Tri-Service General Hospital, National Defense Medical Center, Taipei, 114, Taiwan
| | - Chou-Long Huang
- Department of Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, 75390-8856, USA
| | - Shih-Hua Lin
- Department of Medicine, Division of Nephrology, Tri-Service General Hospital, National Defense Medical Center, Taipei, 114, Taiwan
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23
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Tan H, Bungert-Plümke S, Fahlke C, Stölting G. Reduced Membrane Insertion of CLC-K by V33L Barttin Results in Loss of Hearing, but Leaves Kidney Function Intact. Front Physiol 2017; 8:269. [PMID: 28555110 PMCID: PMC5430073 DOI: 10.3389/fphys.2017.00269] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/12/2017] [Indexed: 12/18/2022] Open
Abstract
In the mammalian ear, transduction of sound stimuli is initiated by K+ entry through mechano-sensitive channels into inner hair cells. K+ entry is driven by a positive endocochlear potential that is maintained by the marginal cell layer of the stria vascularis. This process requires basolateral K+ import by NKCC1 Na+−2Cl−−K+ co-transporters as well as Cl− efflux through ClC-Ka/barttin or ClC-Kb/barttin channels. Multiple mutations in the gene encoding the obligatory CLC-K subunit barttin, BSND, have been identified in patients with Bartter syndrome type IV. These mutations reduce the endocochlear potential and cause deafness. As CLC-K/barttin channels are also expressed in the kidney, patients with Bartter syndrome IV typically also suffer from salt-wasting hyperuria and electrolyte imbalances. However, there was a single report on a BSND mutation that resulted only in deafness, but not kidney disease. We herein studied the functional consequences of another recently discovered BSND mutation that predicts exchange of valine at position 33 by leucine. We combined whole-cell patch clamp, confocal microscopy and protein biochemistry to analyze how V33L affects distinct functions of barttin. We found that V33L reduced membrane insertion of CLC-K/barttin complexes without altering unitary CLC-K channel function. Our findings support the hypothesis of a common pathophysiology for the selective loss of hearing due to an attenuation of the total chloride conductance in the stria vascularis while providing enough residual function to maintain normal kidney function.
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Affiliation(s)
- Hua Tan
- Institute of Complex Systems - Zelluläre Biophysik (ICS-4), Forschungszentrum JülichJülich, Germany
| | - Stefanie Bungert-Plümke
- Institute of Complex Systems - Zelluläre Biophysik (ICS-4), Forschungszentrum JülichJülich, Germany
| | - Christoph Fahlke
- Institute of Complex Systems - Zelluläre Biophysik (ICS-4), Forschungszentrum JülichJülich, Germany
| | - Gabriel Stölting
- Institute of Complex Systems - Zelluläre Biophysik (ICS-4), Forschungszentrum JülichJülich, Germany
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24
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Imbrici P, Tricarico D, Mangiatordi GF, Nicolotti O, Lograno MD, Conte D, Liantonio A. Pharmacovigilance database search discloses ClC-K channels as a novel target of the AT 1 receptor blockers valsartan and olmesartan. Br J Pharmacol 2017; 174:1972-1983. [PMID: 28334417 DOI: 10.1111/bph.13794] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 03/03/2017] [Accepted: 03/04/2017] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Human ClC-K chloride channels are highly attractive targets for drug discovery as they have a variety of important physiological functions and are associated with genetic disorders. These channels are crucial in the kidney as they control chloride reabsorption and water diuresis. In addition, loss-of-function mutations of CLCNKB and BSND genes cause Bartter's syndrome (BS), whereas CLCNKA and CLCNKB gain-of-function polymorphisms predispose to a rare form of salt sensitive hypertension. Both disorders lack a personalized therapy that is in most cases only symptomatic. The aim of this study was to identify novel ClC-K ligands from drugs already on the market, by exploiting the pharmacological side activity of drug molecules available from the FDA Adverse Effects Reporting System database. EXPERIMENTAL APPROACH We searched for drugs having a Bartter-like syndrome as a reported side effect, with the assumption that BS could be causatively related to the block of ClC-K channels. The ability of the selected BS-causing drugs to bind and block ClC-K channels was then validated through an integrated experimental and computational approach based on patch clamp electrophysiology in HEK293 cells and molecular docking simulations. KEY RESULTS Valsartan and olmesartan were able to block ClC-Ka channels and the molecular requirements for effective inhibition of these channels have been identified. CONCLUSION AND IMPLICATIONS These results suggest additional mechanisms of action for these sartans further to their primary AT1 receptor antagonism and propose these compounds as leads for designing new potent ClC-K ligands.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - Domenico Tricarico
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | | | - Orazio Nicolotti
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | | | - Diana Conte
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
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25
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Liu Y, Rafferty TM, Rhee SW, Webber JS, Song L, Ko B, Hoover RS, He B, Mu S. CD8 + T cells stimulate Na-Cl co-transporter NCC in distal convoluted tubules leading to salt-sensitive hypertension. Nat Commun 2017; 8:14037. [PMID: 28067240 PMCID: PMC5227995 DOI: 10.1038/ncomms14037] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 11/23/2016] [Indexed: 12/12/2022] Open
Abstract
Recent studies suggest a role for T lymphocytes in hypertension. However, whether T cells contribute to renal sodium retention and salt-sensitive hypertension is unknown. Here we demonstrate that T cells infiltrate into the kidney of salt-sensitive hypertensive animals. In particular, CD8+ T cells directly contact the distal convoluted tubule (DCT) in the kidneys of DOCA-salt mice and CD8+ T cell-injected mice, leading to up-regulation of the Na-Cl co-transporter NCC, p-NCC and the development of salt-sensitive hypertension. Co-culture with CD8+ T cells upregulates NCC in mouse DCT cells via ROS-induced activation of Src kinase, up-regulation of the K+ channel Kir4.1, and stimulation of the Cl- channel ClC-K. The last event increases chloride efflux, leading to compensatory chloride influx via NCC activation at the cost of increasing sodium retention. Collectively, these findings provide a mechanism for adaptive immunity involvement in the kidney defect in sodium handling and the pathogenesis of salt-sensitive hypertension.
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Affiliation(s)
- Yunmeng Liu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Tonya M Rafferty
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Sung W Rhee
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Jessica S Webber
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Li Song
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Benjamin Ko
- Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA
| | - Robert S Hoover
- Department of Medicine, Division of Nephrology, Emory University, Atlanta, Georgia 30322, USA.,Research Service Atlanta, Veteran's Administration Medical Center, Decatur, Georgia 30033, USA
| | - Beixiang He
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.,Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | - Shengyu Mu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
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26
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Stölting G, Fahlke C. Chloride channels in renal salt and water transport. Acta Physiol (Oxf) 2017; 219:11-13. [PMID: 27636562 DOI: 10.1111/apha.12802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- G. Stölting
- Institute of Complex Systems - Zelluläre Biophysik (ICS-4); Forschungszentrum Jülich; Jülich Germany
| | - C. Fahlke
- Institute of Complex Systems - Zelluläre Biophysik (ICS-4); Forschungszentrum Jülich; Jülich Germany
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27
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O’Sullivan ME, Perez A, Lin R, Sajjadi A, Ricci AJ, Cheng AG. Towards the Prevention of Aminoglycoside-Related Hearing Loss. Front Cell Neurosci 2017; 11:325. [PMID: 29093664 PMCID: PMC5651232 DOI: 10.3389/fncel.2017.00325] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 09/30/2017] [Indexed: 01/08/2023] Open
Abstract
Aminoglycosides are potent antibiotics deployed worldwide despite their known side-effect of sensorineural hearing loss. The main etiology of this sensory deficit is death of inner ear sensory hair cells selectively triggered by aminoglycosides. For decades, research has sought to unravel the molecular events mediating sensory cell demise, emphasizing the roles of reactive oxygen species and their potentials as therapeutic targets. Studies in recent years have revealed candidate transport pathways including the mechanotransducer channel for drug entry into sensory cells. Once inside sensory cells, intracellular targets of aminoglycosides, such as the mitochondrial ribosomes, are beginning to be elucidated. Based on these results, less ototoxic aminoglycoside analogs are being generated and may serve as alternate antimicrobial agents. In this article, we review the latest findings on mechanisms of aminoglycoside entry into hair cells, their intracellular actions and potential therapeutic targets for preventing aminoglycoside ototoxicity.
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Affiliation(s)
- Mary E. O’Sullivan
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Adela Perez
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Randy Lin
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Autefeh Sajjadi
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Anthony J. Ricci
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Anthony J. Ricci Alan G. Cheng
| | - Alan G. Cheng
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- *Correspondence: Anthony J. Ricci Alan G. Cheng
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28
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Barrallo-Gimeno A, Gradogna A, Zanardi I, Pusch M, Estévez R. Regulatory-auxiliary subunits of CLC chloride channel-transport proteins. J Physiol 2016; 593:4111-27. [PMID: 25762128 DOI: 10.1113/jp270057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/15/2015] [Indexed: 02/06/2023] Open
Abstract
The CLC family of chloride channels and transporters is composed by nine members, but only three of them, ClC-Ka/b, ClC-7 and ClC-2, have been found so far associated with auxiliary subunits. These CLC regulatory subunits are small proteins that present few common characteristics among them, both structurally and functionally, and their effects on the corresponding CLC protein are different. Barttin, a protein with two transmembrane domains, is essential for the membrane localization of ClC-K proteins and their activity in the kidney and inner ear. Ostm1 is a protein with a single transmembrane domain and a highly glycosylated N-terminus. Unlike the other two CLC auxiliary subunits, Ostm1 shows a reciprocal relationship with ClC-7 for their stability. The subcellular localization of Ostm1 depends on ClC-7 and not the other way around. ClC-2 is active on its own, but GlialCAM, a transmembrane cell adhesion molecule with two extracellular immunoglobulin (Ig)-like domains, regulates its subcellular localization and activity in glial cells. The common theme for these three proteins is their requirement for a proper homeostasis, since their malfunction leads to distinct diseases. We will review here their properties and their role in normal chloride physiology and the pathological consequences of their improper function.
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Affiliation(s)
- Alejandro Barrallo-Gimeno
- Sección de Fisiología, Departamento de Ciencias Fisiológicas II, University of Barcelona, Barcelona, Spain.,U-750, Centro de investigación en red de enfermedades raras (CIBERER), ISCIII, Barcelona, Spain
| | | | - Ilaria Zanardi
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genoa, Italy
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genoa, Italy
| | - Raúl Estévez
- Sección de Fisiología, Departamento de Ciencias Fisiológicas II, University of Barcelona, Barcelona, Spain.,U-750, Centro de investigación en red de enfermedades raras (CIBERER), ISCIII, Barcelona, Spain
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29
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Stölting G, Bungert-Plümke S, Franzen A, Fahlke C. Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking. J Biol Chem 2015; 290:30406-16. [PMID: 26453302 DOI: 10.1074/jbc.m115.675827] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 12/21/2022] Open
Abstract
ClC-K chloride channels are crucial for auditory transduction and urine concentration. Mutations in CLCNKB, the gene encoding the renal chloride channel hClC-Kb, cause Bartter syndrome type III, a human genetic condition characterized by polyuria, hypokalemia, and alkalosis. In recent years, several Bartter syndrome-associated mutations have been described that result in truncations of the intracellular carboxyl terminus of hClC-Kb. We here used a combination of whole-cell patch clamp, confocal imaging, co-immunoprecipitation, and surface biotinylation to study the functional consequences of a frequent CLCNKB mutation that creates a premature stop codon at Trp-610. We found that W610X leaves the association of hClC-Kb and the accessory subunit barttin unaffected, but impairs its regulation by barttin. W610X attenuates hClC-Kb surface membrane insertion. Moreover, W610X results in hClC-Kb channel opening in the absence of barttin and prevents further barttin-mediated activation. To describe how the carboxyl terminus modifies the regulation by barttin we used V166E rClC-K1. V166E rClC-K1 is active without barttin and exhibits prominent, barttin-regulated voltage-dependent gating. Electrophysiological characterization of truncated V166E rClC-K1 demonstrated that the distal carboxyl terminus is necessary for slow cooperative gating. Since barttin modifies this particular gating process, channels lacking the distal carboxyl-terminal domain are no longer regulated by the accessory subunit. Our results demonstrate that the carboxyl terminus of hClC-Kb is not part of the binding site for barttin, but functionally modifies the interplay with barttin. The loss-of-activation of truncated hClC-Kb channels in heterologous expression systems fully explains the reduced basolateral chloride conductance in affected kidneys and the clinical symptoms of Bartter syndrome patients.
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Affiliation(s)
- Gabriel Stölting
- From the Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich
| | - Stefanie Bungert-Plümke
- From the Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich
| | - Arne Franzen
- From the Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich
| | - Christoph Fahlke
- From the Institute of Complex Systems 4 (ICS-4), Zelluläre Biophysik, Forschungszentrum Jülich, 52425 Jülich
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30
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Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
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31
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Andrini O, Keck M, Briones R, Lourdel S, Vargas-Poussou R, Teulon J. ClC-K chloride channels: emerging pathophysiology of Bartter syndrome type 3. Am J Physiol Renal Physiol 2015; 308:F1324-34. [DOI: 10.1152/ajprenal.00004.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/23/2015] [Indexed: 02/08/2023] Open
Abstract
The mutations in the CLCNKB gene encoding the ClC-Kb chloride channel are responsible for Bartter syndrome type 3, one of the four variants of Bartter syndrome in the genetically based nomenclature. All forms of Bartter syndrome are characterized by hypokalemia, metabolic alkalosis, and secondary hyperaldosteronism, but Bartter syndrome type 3 has the most heterogeneous presentation, extending from severe to very mild. A relatively large number of CLCNKB mutations have been reported, including gene deletions and nonsense or missense mutations. However, only 20 CLCNKB mutations have been functionally analyzed, due to technical difficulties regarding ClC-Kb functional expression in heterologous systems. This review provides an overview of recent progress in the functional consequences of CLCNKB mutations on ClC-Kb chloride channel activity. It has been observed that 1) all ClC-Kb mutants have an impaired expression at the membrane; and 2) a minority of the mutants combines reduced membrane expression with altered pH-dependent channel gating. Although further investigation is needed to fully characterize disease pathogenesis, Bartter syndrome type 3 probably belongs to the large family of conformational diseases, in which the mutations destabilize channel structure, inducing ClC-Kb retention in the endoplasmic reticulum and accelerated channel degradation.
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Affiliation(s)
- Olga Andrini
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Mathilde Keck
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Rodolfo Briones
- Department of Theoretical and Computational Biophysics, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stéphane Lourdel
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Rosa Vargas-Poussou
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Département de Génétique, Paris, France; and
- Université Paris-Descartes, Faculté de Médecine, Paris, France
| | - Jacques Teulon
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
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32
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Wojciechowski D, Fischer M, Fahlke C. Tryptophan Scanning Mutagenesis Identifies the Molecular Determinants of Distinct Barttin Functions. J Biol Chem 2015; 290:18732-43. [PMID: 26063802 DOI: 10.1074/jbc.m114.625376] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Indexed: 01/05/2023] Open
Abstract
CLC-K chloride channels are expressed in the kidney and in the inner ear and require the accessory subunit barttin for proper function and membrane insertion. Barttin exerts multiple functions on CLC-proteins: it modifies protein stability and intracellular trafficking as well as channel activity, ion conduction, and gating. So far, the molecular determinants of these distinct barttin functions have remained elusive. Here we performed serial perturbation mutagenesis to identify the sequence determinants of barttin function. Barttin consists of two transmembrane helices followed by a long intracellular carboxyl terminus, and earlier work demonstrated that the transmembrane core of barttin suffices for most effects on the α-subunit. We individually substituted every amino acid of the predicted transmembrane core (amino acids 9-26 and 35-55) with tryptophan, co-expressed mutant barttin with hClC-Ka or V166E rClC-K1, and characterized CLC-K/barttin channels by patch clamp techniques, biochemistry, and confocal microscopy. The majority of mutations left the chaperone function of barttin, i.e. the effects on endoplasmic reticulum exit and surface membrane insertion, unaffected. In contrast, tryptophan insertion at multiple positions resulted in impaired activity of hClC-Ka/barttin and changes in gating of V166E rClC-K1/barttin. These results demonstrate that mutations in a cluster of hydrophobic residues within transmembrane domain 1 affect barttin-CLC-K interaction and impair gating modification by the accessory subunit. Whereas tight interaction is necessary for functional modification, even impaired association of barttin and CLC-K suffices for normal intracellular trafficking. Our findings allow definition of a likely interaction surface and clarify the mechanisms underlying CLC-K channel modification by barttin.
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Affiliation(s)
- Daniel Wojciechowski
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany and
| | - Martin Fischer
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany and
| | - Christoph Fahlke
- Institute of Complex Systems-Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52428 Jülich Germany
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33
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Steinke KV, Gorinski N, Wojciechowski D, Todorov V, Guseva D, Ponimaskin E, Fahlke C, Fischer M. Human CLC-K Channels Require Palmitoylation of Their Accessory Subunit Barttin to Be Functional. J Biol Chem 2015; 290:17390-400. [PMID: 26013830 DOI: 10.1074/jbc.m114.631705] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Indexed: 11/06/2022] Open
Abstract
CLC-K/barttin chloride channels are essential for NaCl re-absorption in Henle's loop and for potassium secretion by the stria vascularis in the inner ear. Here, we studied the posttranslational modification of such channels by palmitoylation of their accessory subunit barttin. We found that barttin is palmitoylated in vivo and in vitro and identified two conserved cysteine residues at positions 54 and 56 as palmitoylation sites. Point mutations at these two residues reduce the macroscopic current amplitudes in cells expressing CLC-K/barttin channels proportionally to the relative reduction in palmitoylated barttin. CLC-K/barttin expression, plasma membrane insertion, and single channel properties remain unaffected, indicating that these mutations decrease the number of active channels. R8W and G47R, two naturally occurring barttin mutations identified in patients with Bartter syndrome type IV, reduce barttin palmitoylation and CLC-K/barttin channel activity. Palmitoylation of the accessory subunit barttin might thus play a role in chloride channel dysfunction in certain variants of Bartter syndrome. We did not observe pronounced alteration of barttin palmitoylation upon increased salt and water intake or water deprivation, indicating that this posttranslational modification does not contribute to long term adaptation to variable water intake. Our results identify barttin palmitoylation as a novel posttranslational modification of CLC-K/barttin chloride channels.
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Affiliation(s)
- Kim Vanessa Steinke
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Nataliya Gorinski
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Daniel Wojciechowski
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany, Institute of Complex Systems, Zelluläre Biophysik (ICS-4), FZ Jülich, 52428 Jülich, Germany, and
| | - Vladimir Todorov
- Laboratory for Experimental Nephrology, Division of Nephrology, University Hospital Dresden, 01307 Dresden Germany
| | - Daria Guseva
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Evgeni Ponimaskin
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Christoph Fahlke
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), FZ Jülich, 52428 Jülich, Germany, and
| | - Martin Fischer
- From the Institut für Neurophysiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany,
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Chen X, Zhou B, Hou X, Xing J, Zou S, Wu X, Ma B, Shi J. Associations between CLCNKA_B tag SNPs with essential hypertension and interactions between genetic and environmental factors in an island population in China. Clin Exp Hypertens 2015; 37:519-25. [PMID: 25919862 DOI: 10.3109/10641963.2015.1013124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Essential hypertension (EH) is known as the result from the interaction of environmental and genetic factors. We selected tag SNPs of CLCNKA_B genes as gene markers, to elucidate the relationship between CLCNKA_B and EH, and to determine the possible interaction among tag SNPs and dietary factors in island of China. METHODS A case-control study was conducted in Changshan islands of China, blood samples of 806 participants were genotyped, and the general characteristics and dietary habits of them were collected. Unconditional logistic regression (ULR) was used to assess the effects of CLCNKA_B tag SNPs and dietary factors on EH. Generalized multifactor dimensionality reduction (GMDR) was used to test gene-environment interaction for EH risk. RESULTS Four SNPs were identified as the tag SNPs of CLCNKA_B. Recessive model for rs5253 and rs2275166 were marginal associated with the decrease risk of EH (OR = 0.36, 95% CI = 0.12-1.07 for rs5253; OR = 0.40, 95% CI = 0.16-1.05 for rs2275166). In GMDR, the five-factor interaction model of rs1010069, salt, marine products, meat and edible oil consumption was the best model, with a maximum CVC of 10/10 and a TBA of 0.638 (p = 0.001). In ULR, compared with subjects carried wild genotypes and null dietary risk factor, those with three or more dietary risk factors and mutation genotypes had 5.90-fold EH risk (95% CI:2.24-15.53). CONCLUSION Though the single loci of tag SNPs of CLCNKA_B are not enough to significantly increase the EH susceptibility, the combination of CLCNKA tag SNP, salt, marine products, meat and edible oil consumption is associated with elevated risk.
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Affiliation(s)
- Xin Chen
- a Department of Clinical Epidemiology , Institute of Cardiovascular Diseases, and Center of Evidence Based Medicine, the First Affiliated Hospital, China Medical University , Shenyang , China
| | - Bo Zhou
- a Department of Clinical Epidemiology , Institute of Cardiovascular Diseases, and Center of Evidence Based Medicine, the First Affiliated Hospital, China Medical University , Shenyang , China
| | - Xiaowen Hou
- a Department of Clinical Epidemiology , Institute of Cardiovascular Diseases, and Center of Evidence Based Medicine, the First Affiliated Hospital, China Medical University , Shenyang , China
| | - Jiaxin Xing
- b School of Forensic Medicine, China Medical University , Shenyang , China , and
| | - Safeng Zou
- c Department of Rehabilitation , Central Hospital of Dalian Municipal , Dalian , China
| | - Xiaomei Wu
- a Department of Clinical Epidemiology , Institute of Cardiovascular Diseases, and Center of Evidence Based Medicine, the First Affiliated Hospital, China Medical University , Shenyang , China
| | - Bing Ma
- a Department of Clinical Epidemiology , Institute of Cardiovascular Diseases, and Center of Evidence Based Medicine, the First Affiliated Hospital, China Medical University , Shenyang , China
| | - Jingpu Shi
- a Department of Clinical Epidemiology , Institute of Cardiovascular Diseases, and Center of Evidence Based Medicine, the First Affiliated Hospital, China Medical University , Shenyang , China
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Stölting G, Fischer M, Fahlke C. CLC channel function and dysfunction in health and disease. Front Physiol 2014; 5:378. [PMID: 25339907 PMCID: PMC4188032 DOI: 10.3389/fphys.2014.00378] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/12/2014] [Indexed: 01/01/2023] Open
Abstract
CLC channels and transporters are expressed in most tissues and fulfill diverse functions. There are four human CLC channels, ClC-1, ClC-2, ClC-Ka, and ClC-Kb, and five CLC transporters, ClC-3 through −7. Some of the CLC channels additionally associate with accessory subunits. Whereas barttin is mandatory for the functional expression of ClC-K, GlialCam is a facultative subunit of ClC-2 which modifies gating and thus increases the functional variability within the CLC family. Isoform-specific ion conduction and gating properties optimize distinct CLC channels for their cellular tasks. ClC-1 preferentially conducts at negative voltages, and the resulting inward rectification provides a large resting chloride conductance without interference with the muscle action potential. Exclusive opening at voltages negative to the chloride reversal potential allows for ClC-2 to regulate intracellular chloride concentrations. ClC-Ka and ClC-Kb are equally suited for inward and outward currents to support transcellular chloride fluxes. Every human CLC channel gene has been linked to a genetic disease, and studying these mutations has provided much information about the physiological roles and the molecular basis of CLC channel function. Mutations in the gene encoding ClC-1 cause myotonia congenita, a disease characterized by sarcolemmal hyperexcitability and muscle stiffness. Loss-of-function of ClC-Kb/barttin channels impairs NaCl resorption in the limb of Henle and causes hyponatriaemia, hypovolemia and hypotension in patients suffering from Bartter syndrome. Mutations in CLCN2 were found in patients with CNS disorders but the functional role of this isoform is still not understood. Recent links between ClC-1 and epilepsy and ClC-Ka and heart failure suggested novel cellular functions of these proteins. This review aims to survey the knowledge about physiological and pathophysiological functions of human CLC channels in the light of recent discoveries from biophysical, physiological, and genetic studies.
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Affiliation(s)
- Gabriel Stölting
- Institute of Complex Systems-Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich Jülich, Germany
| | - Martin Fischer
- Institut für Neurophysiologie, Medizinische Hochschule Hannover Hannover, Germany
| | - Christoph Fahlke
- Institute of Complex Systems-Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich Jülich, Germany
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Imbrici P, Liantonio A, Gradogna A, Pusch M, Camerino DC. Targeting kidney CLC-K channels: Pharmacological profile in a human cell line versus Xenopus oocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2484-91. [DOI: 10.1016/j.bbamem.2014.05.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/29/2014] [Accepted: 05/16/2014] [Indexed: 10/25/2022]
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Identification and characterization of the zebrafish ClC-2 chloride channel orthologs. Pflugers Arch 2014; 467:1769-81. [DOI: 10.1007/s00424-014-1614-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 09/09/2014] [Accepted: 09/09/2014] [Indexed: 12/31/2022]
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Abstract
Specific channels permit movement of selected ions through cellular membranes, and are of vital importance in a number of physiological processes, particularly in excitable tissues such as nerve and muscle, but also in endocrine organs and in epithelial biology. Disorders of channel proteins are termed channelopathies, and their importance is increasingly recognised within medicine. In the kidney, ion channels have critical roles enabling sodium and potassium reuptake or excretion along the nephron, in magnesium homeostasis, in the control of water reabsorption in the collecting duct, and in determining glomerular permeability. In this review, we assess the channelopathies encountered in each nephron segment, and see how their molecular and genetic characterisation in the past 20–30 years has furthered our understanding of normal kidney physiology and disease processes, aids correct diagnosis and promises future therapeutic opportunities.
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Affiliation(s)
- KW Loudon
- Department of Renal Medicine, Addenbrooke’s Hospital, Cambridge, UK
| | - AC Fry
- Department of Renal Medicine, Addenbrooke’s Hospital, Cambridge, UK
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Catterall WA, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ion channels. Br J Pharmacol 2013; 170:1607-51. [PMID: 24528239 PMCID: PMC3892289 DOI: 10.1111/bph.12447] [Citation(s) in RCA: 224] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
- *
Author for correspondence;
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - William A Catterall
- University of Washington, School of Medicine, Department of PharmacologyBox 357280, Seattle, WA 98195-7280, USA
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Characterization of the mouse ClC-K1/Barttin chloride channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2399-409. [DOI: 10.1016/j.bbamem.2013.06.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 05/28/2013] [Accepted: 06/11/2013] [Indexed: 11/24/2022]
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Gabrielli L, Bonasoni MP, Santini D, Piccirilli G, Chiereghin A, Guerra B, Landini MP, Capretti MG, Lanari M, Lazzarotto T. Human fetal inner ear involvement in congenital cytomegalovirus infection. Acta Neuropathol Commun 2013; 1:63. [PMID: 24252374 PMCID: PMC3893406 DOI: 10.1186/2051-5960-1-63] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 09/23/2013] [Indexed: 01/12/2023] Open
Abstract
Background Congenital cytomegalovirus (CMV) infection is a leading cause of sensorineural hearing loss (SNHL). The mechanisms of pathogenesis of CMV-related SNHL are still unclear. The aim is to study congenital CMV-related damage in the fetal inner ear, in order to better understand the underlying pathophysiology behind CMV-SNHL. Results We studied inner ears and brains of 20 human fetuses, all at 21 week gestational age, with a high viral load in the amniotic fluid, with and without ultrasound (US) brain abnormalities. We evaluated histological brain damage, inner ear infection, local inflammatory response and tissue viral load. Immunohistochemistry revealed that CMV was positive in 14/20 brains (70%) and in the inner ears of 9/20 fetuses (45%). In the cases with inner ear infection, the marginal cell layer of the stria vascularis was always infected, followed by infection in the Reissner’s membrane. The highest tissue viral load was observed in the inner ear with infected Organ of Corti. Vestibular labyrinth showed CMV infection of sensory cells in the utricle and in the crista ampullaris. US cerebral anomalies were detected in 6 cases, and in all those cases, the inner ear was always involved. In the other 14 cases with normal brain scan, histological brain damage was present in 8 fetuses and 3 of them presented inner ear infection. Conclusions CMV-infection of the marginal cell layer of the stria vascularis may alter potassium and ion circulation, dissipating the endocochlear potential with consequent SNHL. Although abnormal cerebral US is highly predictive of brain and inner ear damage, normal US findings cannot exclude them either.
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Denton JS, Pao AC, Maduke M. Novel diuretic targets. Am J Physiol Renal Physiol 2013; 305:F931-42. [PMID: 23863472 PMCID: PMC3798746 DOI: 10.1152/ajprenal.00230.2013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 07/12/2013] [Indexed: 01/11/2023] Open
Abstract
As the molecular revolution continues to inform a deeper understanding of disease mechanisms and pathways, there exist unprecedented opportunities for translating discoveries at the bench into novel therapies for improving human health. Despite the availability of several different classes of antihypertensive medications, only about half of the 67 million Americans with hypertension manage their blood pressure appropriately. A broader selection of structurally diverse antihypertensive drugs acting through different mechanisms would provide clinicians with greater flexibility in developing effective treatment regimens for an increasingly diverse and aging patient population. An emerging body of physiological, genetic, and pharmacological evidence has implicated several renal ion-transport proteins, or regulators thereof, as novel, yet clinically unexploited, diuretic targets. These include the renal outer medullary potassium channel, ROMK (Kir1.1), Kir4.1/5.1 potassium channels, ClC-Ka/b chloride channels, UTA/B urea transporters, the chloride/bicarbonate exchanger pendrin, and the STE20/SPS1-related proline/alanine-rich kinase (SPAK). The molecular pharmacology of these putative targets is poorly developed or lacking altogether; however, recent efforts by a few academic and pharmaceutical laboratories have begun to lessen this critical barrier. Here, we review the evidence in support of the aforementioned proteins as novel diuretic targets and highlight examples where progress toward developing small-molecule pharmacology has been made.
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Affiliation(s)
- Jerod S Denton
- T4208 Medical Center North, 1161 21st Ave. South, Nashville, TN 37232.
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Keck M, Andrini O, Lahuna O, Burgos J, Cid LP, Sepúlveda FV, L‘Hoste S, Blanchard A, Vargas-Poussou R, Lourdel S, Teulon J. NovelCLCNKBMutations Causing Bartter Syndrome Affect Channel Surface Expression. Hum Mutat 2013; 34:1269-78. [DOI: 10.1002/humu.22361] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 05/15/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Mathilde Keck
- UPMC Université Paris 06, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
- INSERM, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
| | - Olga Andrini
- UPMC Université Paris 06, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
- INSERM, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
| | - Olivier Lahuna
- UPMC Université Paris 06, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
- INSERM, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
| | - Johanna Burgos
- Centro de Estudios Científicos; Avenida Arturo Prat 514; Valdivia Chile
| | - L. Pablo Cid
- Centro de Estudios Científicos; Avenida Arturo Prat 514; Valdivia Chile
| | | | - Sébastien L‘Hoste
- UPMC Université Paris 06, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
- INSERM, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
| | - Anne Blanchard
- Assistance Publique-Hôpitaux de Paris; Hôpital Européen Georges Pompidou; Centre d'Investigation Clinique; Paris France
- Université Paris-Descartes; Faculté de Médecine; Paris France
| | - Rosa Vargas-Poussou
- Université Paris-Descartes; Faculté de Médecine; Paris France
- Assistance Publique-Hôpitaux de Paris; Hôpital Européen Georges Pompidou; département de génétique; Paris France
| | - Stéphane Lourdel
- UPMC Université Paris 06, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
- INSERM, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
| | - Jacques Teulon
- UPMC Université Paris 06, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
- INSERM, UMR_S 872; Laboratoire de génomique, physiologie et physiopathologie rénales; Paris France
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Guinamard R, Simard C, Del Negro C. Flufenamic acid as an ion channel modulator. Pharmacol Ther 2013; 138:272-84. [PMID: 23356979 DOI: 10.1016/j.pharmthera.2013.01.012] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 12/26/2012] [Indexed: 12/29/2022]
Abstract
Flufenamic acid has been known since the 1960s to have anti-inflammatory properties attributable to the reduction of prostaglandin synthesis. Thirty years later, flufenamic acid appeared to be an ion channel modulator. Thus, while its use in medicine diminished, its use in ionic channel research expanded. Flufenamic acid commonly not only affects non-selective cation channels and chloride channels, but also modulates potassium, calcium and sodium channels with effective concentrations ranging from 10(-6)M in TRPM4 channel inhibition to 10(-3)M in two-pore outwardly rectifying potassium channel activation. Because flufenamic acid effects develop and reverse rapidly, it is a convenient and widely used tool. However, given the broad spectrum of its targets, experimental results have to be interpreted cautiously. Here we provide an overview of ion channels targeted by flufenamic acid to aid in interpreting its effects at the molecular, cellular, and system levels. If it is used with good practices, flufenamic acid remains a useful tool for ion channel research. Understanding the targets of FFA may help reevaluate its physiological impacts and revive interest in its therapeutic potential.
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Su X, Chang P, Liu Z, Yan M, Liu G, Cui H. Association of CLCNKB haplotypes and hypertension in Mongolian and Han populations. Clin Exp Hypertens 2012; 34:482-7. [PMID: 22578033 DOI: 10.3109/10641963.2012.666602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We investigated a possible association between genetic variations in chloride channel Kb (CLCNKB) gene and essential hypertension (EH) in the Mongolian and Han populations in Inner Mongolia. Our study included 414 unrelated Mongolian herdsmen and 524 Han farmers. Two tagSNPs of CLCNKB (rs945393 and rs10803414) were identified from the Chinese HapMap database based on pairwise r(2) ≥ 0.5 and minor allele frequency ≥0.05. Genotyping was performed using the PCR/ligase detection reaction assay. There was significant difference in allele frequency of rs10803414 between the EH group (35%) and the control group (26%) in the Mongolian population (P < .05). Significant association was identified between rs10803414 and EH in the Mongolian population (P < .05) and rs945393 and EH in the Han population (P < .01). The frequency of haplotype CC in the EH group (9.4%) was significantly higher than in the control group (4.6%) in the Mongolian population; individuals who possessed the CC haplotype had a significantly higher risk of EH in the Mongolian population. There was no association between haplotype and EH in the Han population. After adjusting for age, sex, and other confounding risk factors, only rs10803414 was the risk factor of hypertension in Mongolians. Our results indicate that rs10803414 in CLCNKB confers a significant risk of EH in the Mongolian population and haplotype CC of CLCNKB is a genetic factor for EH in the Mongolian population. Our study expands the association between CLCNKB and EH to a non-European ancestry population and provides the first evidence of a cross-race susceptibility of EH locus.
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Affiliation(s)
- Xiulan Su
- Clinical Medical Research Center of the Affiliated Hospital, Inner Mongolia Medical College, Hohhot, China.
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