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Andrini O, Eladari D, Picard N. ClC-K Kidney Chloride Channels: From Structure to Pathology. Handb Exp Pharmacol 2024; 283:35-58. [PMID: 36811727 DOI: 10.1007/164_2023_635] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The molecular basis of chloride transport varies all along the nephron depending on the tubular segments especially in the apical entry of the cell. The major chloride exit pathway during reabsorption is provided by two kidney-specific ClC chloride channels ClC-Ka and ClC-Kb (encoded by CLCNKA and CLCNKB gene, respectively) corresponding to rodent ClC-K1 and ClC-K2 (encoded by Clcnk1 and Clcnk2). These channels function as dimers and their trafficking to the plasma membrane requires the ancillary protein Barttin (encoded by BSND gene). Genetic inactivating variants of the aforementioned genes lead to renal salt-losing nephropathies with or without deafness highlighting the crucial role of ClC-Ka, ClC-Kb, and Barttin in the renal and inner ear chloride handling. The purpose of this chapter is to summarize the latest knowledge on renal chloride structure peculiarity and to provide some insight on the functional expression on the segments of the nephrons and on the related pathological effects.
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Affiliation(s)
- Olga Andrini
- Univ Lyon, University Claude Bernard Lyon 1, CNRS UMR 5284, INSERM U 1314, Melis, Lyon, France.
| | - Dominique Eladari
- CHU Amiens Picardie, Service de Médecine de Précision des maladies Métaboliques et Rénales, Université de Picardie Jules Verne, Amiens, France
| | - Nicolas Picard
- CNRS, LBTI UMR5305, Université Claude Bernard Lyon 1, Lyon, France
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2
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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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3
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Nojehdeh ST, Mojbafan M, Hooman N, Hoseini R, Otukesh H. Genetic diagnosis of Bartter syndrome in Iranian patients and detection of a novel homozygous CLCNKB mutation. Clin Case Rep 2022; 10:e6698. [PMID: 36514463 PMCID: PMC9734084 DOI: 10.1002/ccr3.6698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 10/28/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022] Open
Abstract
An Iranian girl with clinical symptoms of Bartter syndrome like hypokalemia, polyuria, polydipsia, hyponatremia, and hypochloremic alkalosis was referred to us in whom the CLCNKB gene was genetically evaluated using Sanger sequencing. A homozygous pathogenic variant of c.1332_1335delCTCT was detected in this patient.
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Affiliation(s)
| | - Marzieh Mojbafan
- Department of Medical Genetics, School of MedicineIran University of Medical Sciences (IUMS)TehranIran
- Department of Medical GeneticsAli‐Asghar Children's HospitalTehranIran
| | - Nakysa Hooman
- Clinical research Development CenterIran University of Medical SciencesTehranIran
- Department of Pediatric NephrologyAli‐Asghar Children's HospitalTehranIran
| | - Rozita Hoseini
- Department of Pediatric NephrologyAli‐Asghar Children's HospitalTehranIran
| | - Hasan Otukesh
- Department of Pediatric NephrologyAli‐Asghar Children's HospitalTehranIran
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4
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Singh N, Villoutreix BO. Demystifying the Molecular Basis of Pyrazoloquinolinones Recognition at the Extracellular α1+/β3- Interface of the GABA A Receptor by Molecular Modeling. Front Pharmacol 2020; 11:561834. [PMID: 33041802 PMCID: PMC7518038 DOI: 10.3389/fphar.2020.561834] [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: 05/13/2020] [Accepted: 08/26/2020] [Indexed: 12/16/2022] Open
Abstract
GABAA receptors are pentameric ligand-gated ion channels that serve as major inhibitory neurotransmitter receptors in the mammalian brain and the target of numerous clinically relevant drugs interacting with different ligand binding sites. Here, we report an in silico approach to investigate the binding of pyrazoloquinolinones (PQs) that mediate allosteric effects through the extracellular α+/β- interface of GABAA receptors. First, we docked a potent prototype of PQs into the α1+/β3- site of a homology model of the human α1β3γ2 subtype of the GABAA receptor. Next, for each docking pose, we computationally derived protein-ligand complexes for 18 PQ analogs with known experimental potency. Subsequently, binding energy was calculated for all complexes using the molecular mechanics-generalized Born surface area method. Finally, docking poses were quantitatively assessed in the light of experimental data to derive a binding hypothesis. Collectively, the results indicate that PQs at the α1+/β3- site likely exhibit a common binding mode that can be characterized by a hydrogen bond interaction with β3Q64 and hydrophobic interactions involving residues α1F99, β3Y62, β3M115, α1Y159, and α1Y209. Importantly, our results are in good agreement with the recently resolved cryo-Electron Microscopy structures of the human α1β3γ2 and α1β2γ2 subtypes of GABAA receptors.
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Affiliation(s)
- Natesh Singh
- Univ. Lille, INSERM, Institut Pasteur de Lille, U1177-Drugs and Molecules for Living Systems, Lille, France.,Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Bruno O Villoutreix
- Univ. Lille, INSERM, Institut Pasteur de Lille, U1177-Drugs and Molecules for Living Systems, Lille, France
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5
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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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6
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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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7
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Araújo CET, Oliveira CMC, Barbosa JD, Oliveira-Filho JP, Resende LAL, Badial PR, Araujo-Junior JP, McCue ME, Borges AS. A large intragenic deletion in the CLCN1 gene causes Hereditary Myotonia in pigs. Sci Rep 2019; 9:15632. [PMID: 31666547 PMCID: PMC6821760 DOI: 10.1038/s41598-019-51286-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 09/11/2019] [Indexed: 12/14/2022] Open
Abstract
Mutations in the CLCN1 gene are the primary cause of non-dystrophic Hereditary Myotonia in several animal species. However, there are no reports of Hereditary Myotonia in pigs to date. Therefore, the objective of the present study was to characterize the clinical and molecular findings of Hereditary Myotonia in an inbred pedigree. The clinical, electromyographic, histopathological, and molecular findings were evaluated. Clinically affected pigs presented non-dystrophic recessive Hereditary Myotonia. Nucleotide sequence analysis of the entire coding region of the CLCN1 gene revealed the absence of the exons 15 and 16 in myotonic animals. Analysis of the genomic region flanking the deletion unveiled a large intragenic deletion of 4,165 nucleotides. Interestingly, non-related, non-myotonic pigs expressed transcriptional levels of an alternate transcript (i.e., X2) that was identical to the deleted X1 transcript of myotonic pigs. All myotonic pigs and their progenitors were homozygous recessive and heterozygous, respectively, for the 4,165-nucleotide deletion. This is the first study reporting Hereditary Myotonia in pigs and characterizing its clinical and molecular findings. Moreover, to the best of our knowledge, Hereditary Myotonia has never been associated with a genomic deletion in the CLCN1 gene in any other species.
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Affiliation(s)
- C E T Araújo
- São Paulo State University (UNESP), School of Veterinary Medicine and Animal Science, Botucatu, São Paulo, Brazil
| | - C M C Oliveira
- Instituto de Medicina Veterinária, Universidade Federal do Pará, Campus Castanhal, PA, Brazil
| | - J D Barbosa
- Instituto de Medicina Veterinária, Universidade Federal do Pará, Campus Castanhal, PA, Brazil
| | - J P Oliveira-Filho
- São Paulo State University (UNESP), School of Veterinary Medicine and Animal Science, Botucatu, São Paulo, Brazil
| | - L A L Resende
- São Paulo State University (UNESP), Medical School, Botucatu, Brazil
| | - P R Badial
- Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Starkville, MS, USA
| | - J P Araujo-Junior
- São Paulo State University (UNESP), Institute of Bioscience, Botucatu, Brazil
| | - M E McCue
- College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota, 55108, USA
| | - A S Borges
- São Paulo State University (UNESP), School of Veterinary Medicine and Animal Science, Botucatu, São Paulo, Brazil.
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8
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González-Alemán R, Hernández-Castillo D, Caballero J, Montero-Cabrera LA. Quality Threshold Clustering of Molecular Dynamics: A Word of Caution. J Chem Inf Model 2019; 60:467-472. [PMID: 31532987 DOI: 10.1021/acs.jcim.9b00558] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Clustering Molecular Dynamics trajectories is a common analysis that allows grouping together similar conformations. Several algorithms have been designed and optimized to perform this routine task, and among them, Quality Threshold stands as a very attractive option. This algorithm guarantees that in retrieved clusters no pair of frames will have a similarity value greater than a specified threshold, and hence, a set of strongly correlated frames are obtained for each cluster. In this work, it is shown that various commonly used software implementations are flawed by confusing Quality Threshold with another simplistic well-known clustering algorithm published by Daura et al. (Daura, X.; van Gunsteren, W. F.; Jaun, B.; Mark, A. E.; Gademann, K.; Seebach, D. Peptide Folding: When Simulation Meets Experiment. Angew. Chemie Int. Ed. 1999, 38 (1/2), 236-240). Daura's algorithm does not impose any quality threshold for the frames contained in retrieved clusters, bringing unrelated structural configurations altogether. The advantages of using Quality Threshold whenever possible to explore Molecular Dynamic trajectories is exemplified. An in-house implementation of the original Quality Threshold algorithm has been developed in order to illustrate our comments, and its code is freely available for further use by the scientific community.
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Affiliation(s)
- Roy González-Alemán
- Laboratorio de Química Computacional y Teórica, Facultad de Química , Universidad de La Habana , 10400 La Habana , Cuba
| | - David Hernández-Castillo
- Laboratorio de Química Computacional y Teórica, Facultad de Química , Universidad de La Habana , 10400 La Habana , Cuba
| | - Julio Caballero
- Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería en Bioinformática , Universidad de Talca , 2 Norte 685, Casilla 721 , Talca , Chile
| | - Luis A Montero-Cabrera
- Laboratorio de Química Computacional y Teórica, Facultad de Química , Universidad de La Habana , 10400 La Habana , Cuba
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9
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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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10
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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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11
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Altamura C, Mangiatordi GF, Nicolotti O, Sahbani D, Farinato A, Leonetti F, Carratù MR, Conte D, Desaphy JF, Imbrici P. Mapping ligand binding pockets in chloride ClC-1 channels through an integrated in silico and experimental approach using anthracene-9-carboxylic acid and niflumic acid. Br J Pharmacol 2018; 175:1770-1780. [PMID: 29500929 DOI: 10.1111/bph.14192] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 02/19/2018] [Accepted: 02/23/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND PURPOSE Although chloride channels are involved in several physiological processes and acquired diseases, the availability of compounds selectively targeting CLC proteins is limited. ClC-1 channels are responsible for sarcolemma repolarization after an action potential in skeletal muscle and have been associated with myotonia congenita and myotonic dystrophy as well as with other muscular physiopathological conditions. To date only a few ClC-1 blockers have been discovered, such as anthracene-9-carboxylic acid (9-AC) and niflumic acid (NFA), whereas no activator exists. The absence of a ClC-1 structure and the limited information regarding the binding pockets in CLC channels hamper the identification of improved modulators. EXPERIMENTAL APPROACH Here we provide an in-depth characterization of drug binding pockets in ClC-1 through an integrated in silico and experimental approach. We first searched putative cavities in a homology model of ClC-1 built upon an eukaryotic CLC crystal structure, and then validated in silico data by measuring the blocking ability of 9-AC and NFA on mutant ClC-1 channels expressed in HEK 293 cells. KEY RESULTS We identified four putative binding cavities in ClC-1. 9-AC appears to interact with residues K231, R421 and F484 within the channel pore. We also identified one preferential binding cavity for NFA and propose R421 and F484 as critical residues. CONCLUSIONS AND IMPLICATIONS This study represents the first effort to delineate the binding sites of ClC-1. This information is fundamental to discover compounds useful in the treatment of ClC-1-associated dysfunctions and might represent a starting point for specifically targeting other CLC proteins.
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Affiliation(s)
- C Altamura
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - G F Mangiatordi
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - O Nicolotti
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - D Sahbani
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - A Farinato
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - F Leonetti
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - M R Carratù
- Department of Biomedical Sciences and Human Oncology, University of Bari 'Aldo Moro', Bari, Italy
| | - D Conte
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
| | - J-F Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari 'Aldo Moro', Bari, Italy
| | - P Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari 'Aldo Moro', Bari, Italy
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