1
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Wan Y, Guo S, Zhen W, Xu L, Chen X, Liu F, Shen Y, Liu S, Hu L, Wang X, Ye F, Wang Q, Wen H, Yang F. Structural basis of adenine nucleotides regulation and neurodegenerative pathology in ClC-3 exchanger. Nat Commun 2024; 15:6654. [PMID: 39107281 PMCID: PMC11303396 DOI: 10.1038/s41467-024-50975-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 07/25/2024] [Indexed: 08/10/2024] Open
Abstract
The ClC-3 chloride/proton exchanger is both physiologically and pathologically critical, as it is potentiated by ATP to detect metabolic energy level and point mutations in ClC-3 lead to severe neurodegenerative diseases in human. However, why this exchanger is differentially modulated by ATP, ADP or AMP and how mutations caused gain-of-function remains largely unknow. Here we determine the high-resolution structures of dimeric wildtype ClC-3 in the apo state and in complex with ATP, ADP and AMP, and the disease-causing I607T mutant in the apo and ATP-bounded state by cryo-electron microscopy. In combination with patch-clamp recordings and molecular dynamic simulations, we reveal how the adenine nucleotides binds to ClC-3 and changes in ion occupancy between apo and ATP-bounded state. We further observe I607T mutation induced conformational changes and augments in current. Therefore, our study not only lays the structural basis of adenine nucleotides regulation in ClC-3, but also clearly indicates the target region for drug discovery against ClC-3 mediated neurodegenerative diseases.
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Affiliation(s)
- Yangzhuoqun Wan
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Shuangshuang Guo
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Wenxuan Zhen
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Lizhen Xu
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Xiaoying Chen
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China
| | - Fangyue Liu
- Department of Neurobiology and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Shen
- Department of Neurobiology and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shuangshuang Liu
- Core Facilities, Zhejiang University School of Medicine, Hangzhou, China
| | - Lidan Hu
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | | | | | | | - Han Wen
- DP Technology, Beijing, China.
- Institute for Advanced Algorithms Research, Shanghai, China.
- State Key Laboratory of Medical Proteomics, Shanghai, China.
- AI for Science Institute, Beijing, China.
- National Key Laboratory of Lead Druggability Research, Beijing, China.
| | - Fan Yang
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China.
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2
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Kwon HC, Fairclough RH, Chen TY. Insights into CLC-0's Slow-Gating from Intracellular Proton Inhibition. Int J Mol Sci 2024; 25:7796. [PMID: 39063037 PMCID: PMC11276645 DOI: 10.3390/ijms25147796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/28/2024] Open
Abstract
The opening of the Torpedo CLC-0 chloride (Cl-) channel is known to be regulated by two gating mechanisms: fast gating and slow (common) gating. The structural basis underlying the fast-gating mechanism is better understood than that of the slow-gating mechanism, which is still largely a mystery. Our previous study on the intracellular proton (H+i)-induced inhibition of the CLC-0 anionic current led to the conclusion that the inhibition results from the slow-gate closure (also called inactivation). The conclusion was made based on substantial evidence such as a large temperature dependence of the H+i inhibition similar to that of the channel inactivation, a resistance to the H+i inhibition in the inactivation-suppressed C212S mutant, and a similar voltage dependence between the current recovery from the H+i inhibition and the recovery from the channel inactivation. In this work, we further examine the mechanism of the H+i inhibition of wild-type CLC-0 and several mutants. We observe that an anion efflux through the pore of CLC-0 accelerates the recovery from the H+i-induced inhibition, a process corresponding to the slow-gate opening. Furthermore, various inactivation-suppressed mutants exhibit different current recovery kinetics, suggesting the existence of multiple inactivated states (namely, slow-gate closed states). We speculate that protonation of the pore of CLC-0 increases the binding affinity of permeant anions in the pore, thereby generating a pore blockage of ion flow as the first step of inactivation. Subsequent complex protein conformational changes further transition the CLC-0 channel to deeper inactivated states.
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Affiliation(s)
- Hwoi Chan Kwon
- Biophysics Graduate Program, University of California, Davis, CA 95618, USA; (H.C.K.); (R.H.F.)
| | - Robert H. Fairclough
- Biophysics Graduate Program, University of California, Davis, CA 95618, USA; (H.C.K.); (R.H.F.)
- Department of Neurology, University of California, Davis, CA 95618, USA
| | - Tsung-Yu Chen
- Biophysics Graduate Program, University of California, Davis, CA 95618, USA; (H.C.K.); (R.H.F.)
- Department of Neurology, University of California, Davis, CA 95618, USA
- Center for Neuroscience, University of California, 1544 Newton Court, Davis, CA 95618, USA
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3
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Kwon HC, Fairclough RH, Chen TY. Biophysical and Pharmacological Insights to CLC Chloride Channels. Handb Exp Pharmacol 2024; 283:1-34. [PMID: 35768555 DOI: 10.1007/164_2022_594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The CLC family encompasses two functional categories of transmembrane proteins: chloride conducting channels and proton-chloride antiporters. All members in this chloride channel/transporter family consist of two identical protein subunits, and each subunit forms an independent ion-transport pathway, a structural architecture known as "double barrel." These CLC proteins serve biological functions ranging from membrane excitability and cell volume regulation to acidification of endosomes. Despite their ubiquitous expression, physiological significance, and resolved molecular structures of some of the family members, the mechanisms governing these molecules' biophysical functions are still not completely settled. However, a series of functional and structural studies have brought insights into interesting questions related to these proteins. This chapter explores the functional peculiarities underlying CLC channels aided by information observed from the chloride-proton antiporters in the CLC family. The overall structural features of these CLC proteins will be presented, and the biophysical functions will be addressed. Finally, the mechanism of pharmacological agents that interact with CLC channels will also be discussed.
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Affiliation(s)
- Hwoi Chan Kwon
- Center for Neuroscience and Biophysics Graduate Group, University of California, Davis, CA, USA
| | - Robert H Fairclough
- Department of Neurology and the Biophysics Graduate Group, University of California, Davis, CA, USA
| | - Tsung-Yu Chen
- Center for Neuroscience, Department of Neurology, and Biophysics Graduate Group, University of California, Davis, CA, USA.
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4
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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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5
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De Jesús-Pérez JJ, Méndez-Maldonado GA, López-Romero AE, Esparza-Jasso D, González-Hernández IL, De la Rosa V, Gastélum-Garibaldi R, Sánchez-Rodríguez JE, Arreola J. Electro-steric opening of the CLC-2 chloride channel gate. Sci Rep 2021; 11:13127. [PMID: 34162897 PMCID: PMC8222222 DOI: 10.1038/s41598-021-92247-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 06/04/2021] [Indexed: 01/18/2023] Open
Abstract
The widely expressed two-pore homodimeric inward rectifier CLC-2 chloride channel regulates transepithelial chloride transport, extracellular chloride homeostasis, and neuronal excitability. Each pore is independently gated at hyperpolarized voltages by a conserved pore glutamate. Presumably, exiting chloride ions push glutamate outwardly while external protonation stabilizes it. To understand the mechanism of mouse CLC-2 opening we used homology modelling-guided structure-function analysis. Structural modelling suggests that glutamate E213 interacts with tyrosine Y561 to close a pore. Accordingly, Y561A and E213D mutants are activated at less hyperpolarized voltages, re-opened at depolarized voltages, and fast and common gating components are reduced. The double mutant cycle analysis showed that E213 and Y561 are energetically coupled to alter CLC-2 gating. In agreement, the anomalous mole fraction behaviour of the voltage dependence, measured by the voltage to induce half-open probability, was strongly altered in these mutants. Finally, cytosolic acidification or high extracellular chloride concentration, conditions that have little or no effect on WT CLC-2, induced reopening of Y561 mutants at positive voltages presumably by the inward opening of E213. We concluded that the CLC-2 gate is formed by Y561-E213 and that outward permeant anions open the gate by electrostatic and steric interactions.
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Affiliation(s)
- José J De Jesús-Pérez
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, 78290, San Luis Potosí, SLP, Mexico
| | - G Arlette Méndez-Maldonado
- Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. M. García Barragán #1421, 44430, Guadalajara, Jalisco, Mexico
| | - Ana E López-Romero
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, 78290, San Luis Potosí, SLP, Mexico
| | - David Esparza-Jasso
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, 78290, San Luis Potosí, SLP, Mexico
| | - Irma L González-Hernández
- Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. M. García Barragán #1421, 44430, Guadalajara, Jalisco, Mexico
| | - Víctor De la Rosa
- CONACYT, School of Medicine, Universidad Autónoma de San Luis Potosí, Ave. V. Carranza 2005, Los Filtros, 78290, San Luis Potosí, SLP, Mexico
| | - Roberto Gastélum-Garibaldi
- Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. M. García Barragán #1421, 44430, Guadalajara, Jalisco, Mexico
| | - Jorge E Sánchez-Rodríguez
- Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. M. García Barragán #1421, 44430, Guadalajara, Jalisco, Mexico
| | - Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, 78290, San Luis Potosí, SLP, Mexico.
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6
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Kwon HC, Yu Y, Fairclough RH, Chen TY. Proton-dependent inhibition, inverted voltage activation, and slow gating of CLC-0 Chloride Channel. PLoS One 2020; 15:e0240704. [PMID: 33362212 PMCID: PMC7757909 DOI: 10.1371/journal.pone.0240704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 12/03/2020] [Indexed: 11/21/2022] Open
Abstract
CLC-0, a prototype Cl- channel in the CLC family, employs two gating mechanisms that control its ion-permeation pore: fast gating and slow gating. The negatively-charged sidechain of a pore glutamate residue, E166, is known to be the fast gate, and the swinging of this sidechain opens or closes the pore of CLC-0 on the millisecond time scale. The other gating mechanism, slow gating, operates with much slower kinetics in the range of seconds to tens or even hundreds of seconds, and it is thought to involve still-unknown conformational rearrangements. Here, we find that low intracellular pH (pHi) facilitates the closure of the CLC-0’s slow gate, thus generating current inhibition. The rate of low pHi-induced current inhibition increases with intracellular H+ concentration ([H+]i)—the time constants of current inhibition by low pHi = 4.5, 5.5 and 6 are roughly 0.1, 1 and 10 sec, respectively, at room temperature. In comparison, the time constant of the slow gate closure at pHi = 7.4 at room temperature is hundreds of seconds. The inhibition by low pHi is significantly less prominent in mutants favoring the slow-gate open state (such as C212S and Y512A), further supporting the fact that intracellular H+ enhances the slow-gate closure in CLC-0. A fast inhibition by low pHi causes an apparent inverted voltage-dependent activation in the wild-type CLC-0, a behavior similar to those in some channel mutants such as V490W in which only membrane hyperpolarization can open the channel. Interestingly, when V490W mutation is constructed in the background of C212S or Y512A mutation, the inverted voltage-dependent activation disappears. We propose that the slow kinetics of CLC-0’s slow-gate closure may be due to low [H+]i rather than due to the proposed large conformational change of the channel protein. Our results also suggest that the inverted voltage-dependent opening observed in some mutant channels may result from fast closure of the slow gate by the mutations.
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Affiliation(s)
- Hwoi Chan Kwon
- Biophysics Graduate Program, University of California, Davis, California, United States of America
| | - Yawei Yu
- BMCDB Graduate Program, University of California, Davis, California, United States of America
| | - Robert H. Fairclough
- Biophysics Graduate Program, University of California, Davis, California, United States of America
- BMCDB Graduate Program, University of California, Davis, California, United States of America
- Center for Neuroscience, University of California, Davis, California, United States of America
| | - Tsung-Yu Chen
- Biophysics Graduate Program, University of California, Davis, California, United States of America
- BMCDB Graduate Program, University of California, Davis, California, United States of America
- Department of Neurology, University of California, Davis, California, United States of America
- Center for Neuroscience, University of California, Davis, California, United States of America
- * E-mail:
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7
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Altamura C, Ivanova EA, Imbrici P, Conte E, Camerino GM, Dadali EL, Polyakov AV, Kurbatov SA, Girolamo F, Carratù MR, Desaphy JF. Pathomechanisms of a CLCN1 Mutation Found in a Russian Family Suffering From Becker's Myotonia. Front Neurol 2020; 11:1019. [PMID: 33013670 PMCID: PMC7500137 DOI: 10.3389/fneur.2020.01019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 08/04/2020] [Indexed: 11/13/2022] Open
Abstract
Objective: Myotonia congenita (MC) is a rare muscle disease characterized by sarcolemma over-excitability inducing skeletal muscle stiffness. It can be inherited either as an autosomal dominant (Thomsen's disease) or an autosomal recessive (Becker's disease) trait. Both types are caused by loss-of-function mutations in the CLCN1 gene, encoding for ClC-1 chloride channel. We found a ClC-1 mutation, p.G411C, identified in Russian patients who suffered from a severe form of Becker's disease. The purpose of this study was to provide a solid correlation between G411C dysfunction and clinical symptoms in the affected patient. Methods: We provide clinical and genetic information of the proband kindred. Functional studies include patch-clamp electrophysiology, biotinylation assay, western blot analysis, and confocal imaging of G411C and wild-type ClC-1 channels expressed in HEK293T cells. Results: The G411C mutation dramatically abolished chloride currents in transfected HEK cells. Biochemical experiments revealed that the majority of G411C mutant channels did not reach the plasma membrane but remained trapped in the cytoplasm. Treatment with the proteasome inhibitor MG132 reduced the degradation rate of G411C mutant channels, leading to their expression at the plasma membrane. However, despite an increase in cell surface expression, no significant chloride current was recorded in the G411C-transfected cell treated with MG132, suggesting that this mutation produces non-functional ClC-1 chloride channels. Conclusion: These results suggest that the molecular pathophysiology of G411C is linked to a reduced plasma membrane expression and biophysical dysfunction of mutant channels, likely due to a misfolding defect. Chloride current abolition confirms that the mutation is responsible for the clinical phenotype.
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Affiliation(s)
- Concetta Altamura
- Section of Pharmacology, Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Evgeniya A Ivanova
- N.P. Bochkov's Research Centre for Medical Genetics, Federal State Budgetary Scientific Institution, Moscow, Russia
| | - Paola Imbrici
- Section of Pharmacology, Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Elena Conte
- Section of Pharmacology, Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Giulia Maria Camerino
- Section of Pharmacology, Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Elena L Dadali
- N.P. Bochkov's Research Centre for Medical Genetics, Federal State Budgetary Scientific Institution, Moscow, Russia
| | - Alexander V Polyakov
- N.P. Bochkov's Research Centre for Medical Genetics, Federal State Budgetary Scientific Institution, Moscow, Russia
| | | | - Francesco Girolamo
- Unit of Human Anatomy and Histology, Department of Basic Medical Sciences, Neuroscience, and Sense Organs, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Maria Rosaria Carratù
- Section of Pharmacology, Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Jean-François Desaphy
- Section of Pharmacology, Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
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8
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Martínez-Rojas VA, Jiménez-Garduño AM, Michelatti D, Tosatto L, Marchioretto M, Arosio D, Basso M, Pennuto M, Musio C. ClC-2-like Chloride Current Alterations in a Cell Model of Spinal and Bulbar Muscular Atrophy, a Polyglutamine Disease. J Mol Neurosci 2020; 71:662-674. [PMID: 32856205 DOI: 10.1007/s12031-020-01687-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 08/14/2020] [Indexed: 12/21/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by expansions of a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is associated with the progressive loss of lower motor neurons, together with muscle weakness and atrophy. PolyQ-AR is converted to a toxic species upon binding to its natural ligands, testosterone, and dihydrotestosterone (DHT). Our previous patch-clamp studies on a motor neuron-derived cell model of SBMA showed alterations in voltage-gated ion currents. Here, we identified and characterized chloride currents most likely belonging to the chloride channel-2 (ClC-2) subfamily, which showed significantly increased amplitudes in the SBMA cells. The treatment with the pituitary adenylyl cyclase-activating polypeptide (PACAP), a neuropeptide with a proven protective effect in a mouse model of SBMA, recovered chloride channel current alterations in SBMA cells. These observations suggest that the CIC-2 currents are affected in SBMA, an alteration that may contribute and potentially determine the pathophysiology of the disease.
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Affiliation(s)
- Vladimir A Martínez-Rojas
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Aura M Jiménez-Garduño
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.,Departamento de Ciencias de la Salud, Escuela de Ciencias, Universidad de las Américas Puebla (UDLAP), San Andrés Cholula, Puebla, Mexico
| | - Daniela Michelatti
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.,CIBIO Department, Laboratory of Chromatin Biology and Epigenetics, University of Trento, Trento, Italy
| | - Laura Tosatto
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Marta Marchioretto
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Daniele Arosio
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy
| | - Manuela Basso
- CIBIO Department, Laboratory of Transcriptional Neurobiology, University of Trento, Trento, Italy
| | - Maria Pennuto
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Padova Neuroscience Center (PNC), University of Padova, Padova, Italy.,Veneto Institute of Molecular Medicine, Padova, Italy
| | - Carlo Musio
- Institute of Biophysics (IBF), Trento Unit, National Research Council (CNR) & LabSSAH, Bruno Kessler Foundation (FBK), Trento, Italy.
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9
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Zhao C, Tang D, Huang H, Tang H, Yang Y, Yang M, Luo Y, Tao H, Tang J, Zhou X, Shi X. Myotonia congenita and periodic hypokalemia paralysis in a consanguineous marriage pedigree: Coexistence of a novel CLCN1 mutation and an SCN4A mutation. PLoS One 2020; 15:e0233017. [PMID: 32407401 PMCID: PMC7224471 DOI: 10.1371/journal.pone.0233017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/26/2020] [Indexed: 11/18/2022] Open
Abstract
Myotonia congenita and hypokalemic periodic paralysis type 2 are both rare genetic channelopathies caused by mutations in the CLCN1 gene encoding voltage-gated chloride channel CLC-1 and the SCN4A gene encoding voltage-gated sodium channel Nav1.4. The patients with concomitant mutations in both genes manifested different unique symptoms from mutations in these genes separately. Here, we describe a patient with myotonia and periodic paralysis in a consanguineous marriage pedigree. By using whole-exome sequencing, a novel F306S variant in the CLCN1 gene and a known R222W mutation in the SCN4A gene were identified in the pedigree. Patch clamp analysis revealed that the F306S mutant reduced the opening probability of CLC-1 and chloride conductance. Our study expanded the CLCN1 mutation database. We emphasized the value of whole-exome sequencing for differential diagnosis in atypical myotonic patients.
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Affiliation(s)
- Chenyu Zhao
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - DongFang Tang
- The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
| | - Hui Huang
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Haiyan Tang
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yuan Yang
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Intensive Care Unit, Peking University Cancer Hospital & Institute, Beijing, China
| | - Min Yang
- Department of Rehabilitation, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yingying Luo
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Huai Tao
- Depatment of Biochemistry and Molecular Biology, Hunan University of Chinese Medicine, Changsha, Hunan, China
| | - Jianguang Tang
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Xi Zhou
- The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China
- * E-mail: (XZ); (XLS)
| | - Xiaoliu Shi
- Department of Medical Genetics, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
- * E-mail: (XZ); (XLS)
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10
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Altamura C, Desaphy JF, Conte D, De Luca A, Imbrici P. Skeletal muscle ClC-1 chloride channels in health and diseases. Pflugers Arch 2020; 472:961-975. [PMID: 32361781 DOI: 10.1007/s00424-020-02376-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/18/2020] [Accepted: 03/31/2020] [Indexed: 12/14/2022]
Abstract
In 1970, the study of the pathomechanisms underlying myotonia in muscle fibers isolated from myotonic goats highlighted the importance of chloride conductance for skeletal muscle function; 20 years later, the human ClC-1 chloride channel has been cloned; last year, the crystal structure of human protein has been solved. Over the years, the efforts of many researchers led to significant advances in acknowledging the role of ClC-1 in skeletal muscle physiology and the mechanisms through which ClC-1 dysfunctions lead to impaired muscle function. The wide spectrum of pathophysiological conditions associated with modification of ClC-1 activity, either as the primary cause, such as in myotonia congenita, or as a secondary adaptive mechanism in other neuromuscular diseases, supports the idea that ClC-1 is relevant to preserve not only for skeletal muscle excitability, but also for skeletal muscle adaptation to physiological or harmful events. Improving this understanding could open promising avenues toward the development of selective and safe drugs targeting ClC-1, with the aim to restore normal muscle function. This review summarizes the most relevant research on ClC-1 channel physiology, associated diseases, and pharmacology.
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Affiliation(s)
- Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari "Aldo Moro", Bari, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari "Aldo Moro", Bari, Italy
| | - Diana Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy.
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11
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Jeng CJ, Fu SJ, You CY, Peng YJ, Hsiao CT, Chen TY, Tang CY. Defective Gating and Proteostasis of Human ClC-1 Chloride Channel: Molecular Pathophysiology of Myotonia Congenita. Front Neurol 2020; 11:76. [PMID: 32117034 PMCID: PMC7026490 DOI: 10.3389/fneur.2020.00076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 01/22/2020] [Indexed: 01/17/2023] Open
Abstract
The voltage-dependent ClC-1 chloride channel, whose open probability increases with membrane potential depolarization, belongs to the superfamily of CLC channels/transporters. ClC-1 is almost exclusively expressed in skeletal muscles and is essential for stabilizing the excitability of muscle membranes. Elucidation of the molecular structures of human ClC-1 and several CLC homologs provides important insight to the gating and ion permeation mechanisms of this chloride channel. Mutations in the human CLCN1 gene, which encodes the ClC-1 channel, are associated with a hereditary skeletal muscle disease, myotonia congenita. Most disease-causing CLCN1 mutations lead to loss-of-function phenotypes in the ClC-1 channel and thus increase membrane excitability in skeletal muscles, consequently manifesting as delayed relaxations following voluntary muscle contractions in myotonic subjects. The inheritance pattern of myotonia congenita can be autosomal dominant (Thomsen type) or recessive (Becker type). To date over 200 myotonia-associated ClC-1 mutations have been identified, which are scattered throughout the entire protein sequence. The dominant inheritance pattern of some myotonia mutations may be explained by a dominant-negative effect on ClC-1 channel gating. For many other myotonia mutations, however, no clear relationship can be established between the inheritance pattern and the location of the mutation in the ClC-1 protein. Emerging evidence indicates that the effects of some mutations may entail impaired ClC-1 protein homeostasis (proteostasis). Proteostasis of membrane proteins comprises of biogenesis at the endoplasmic reticulum (ER), trafficking to the surface membrane, and protein turn-over at the plasma membrane. Maintenance of proteostasis requires the coordination of a wide variety of different molecular chaperones and protein quality control factors. A number of regulatory molecules have recently been shown to contribute to post-translational modifications of ClC-1 and play critical roles in the ER quality control, membrane trafficking, and peripheral quality control of this chloride channel. Further illumination of the mechanisms of ClC-1 proteostasis network will enhance our understanding of the molecular pathophysiology of myotonia congenita, and may also bring to light novel therapeutic targets for skeletal muscle dysfunction caused by myotonia and other pathological conditions.
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Affiliation(s)
- Chung-Jiuan Jeng
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Ssu-Ju Fu
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Ying You
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Jheng Peng
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Cheng-Tsung Hsiao
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Tsung-Yu Chen
- Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - Chih-Yung Tang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.,College of Medicine, Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
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12
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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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13
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Rohrbough J, Nguyen HN, Lamb FS. Modulation of ClC-3 gating and proton/anion exchange by internal and external protons and the anion selectivity filter. J Physiol 2018; 596:4091-4119. [PMID: 29917234 DOI: 10.1113/jp276332] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/07/2018] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS The ClC-3 2Cl- /1H+ exchanger modulates endosome pH and Cl- concentration. We investigated the relationships between ClC-3-mediated ion transport (steady-state transport current, ISS ), gating charge (Q) and cytoplasmic alkalization. ClC-3 transport is functionally unidirectional. ClC-5 and ClC-3 display indistinguishable exchange ratios, but ClC-3 cycling is less "efficient", as reflected by a large Q/ISS . An M531A mutation predicted to increase water-wire stability and cytoplasmic proton supply improves efficiency. Protonation (pH 5.0) of the outer glutamate gate (Gluext ; E224) reduces Q, inhibits transport, and weakens coupling. Removal of the central tyrosine anion gate (Y572S) greatly increases uncoupled anion current. Tyrosine -OH removal (Y572F) alters anion selectivity and impairs coupling. E224 and Y572 act as anion barriers, and contribute to gating. The Y572 side chain and -OH regulate Q movement kinetics and voltage dependence. E224 and Y572 interact to create a "closed" inner gate conformation that maintains coupling during cycling. ABSTRACT We utilized plasma membrane-localized ClC-3 to investigate relationships between steady-state transport current (ISS ), gating charge (Q) movement, and cytoplasmic alkalization rate. ClC-3 exhibited lower transport efficiency than ClC-5, as reflected by a larger Q/ISS ratio, but an indistinguishable Cl- /H+ coupling ratio. External SCN- reduced H+ transport rate and uncoupled anion/H+ exchange by 80-90%. Removal of the external gating glutamate ("Gluext ") (E224A mutation) reduced Q and abolished H+ transport. We hypothesized that Methionine 531 (M531) impedes "water wire" H+ transfer from the cytoplasm to E224. Accordingly, an M531A mutation decreased the Q/ISS ratio by 50% and enhanced H+ transport. External protons (pH 5.0) inhibited ISS and markedly reduced Q while shifting the Q-voltage (V) relationship positively. The Cl- /H+ coupling ratio at pH 5.0 was significantly increased, consistent with externally protonated Gluext adopting an outward/open position. Internal "anion gate" removal (Y572S) dramatically increased ISS and impaired coupling, without slowing H+ transport rate. Loss of both gates (Y572S/E224A) resulted in a large "open pore" conductance. Y572F (removing only the phenolic hydroxide) and Y572S shortened Q duration similarly, resulting in faster Q kinetics at all voltages. These data reveal a complex relationship between Q and ion transport. Q/ISS must be assessed together with coupling ratio to properly interpret efficiency. Coupling and transport rate are influenced by the anion, internal proton supply and external protons. Y572 regulates H+ coupling as well as anion selectivity, and interacts directly with E224. Disruption of this "closed gate" conformation by internal protons may represent a critical step in the ClC-3 transport cycle.
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Affiliation(s)
- Jeffrey Rohrbough
- Departments of Pediatrics and Molecular Physiology & Biophysics, Monroe Carell Children's Hospital at Vanderbilt University, Nashville, TN, USA
| | - Hong-Ngan Nguyen
- Departments of Pediatrics and Molecular Physiology & Biophysics, Monroe Carell Children's Hospital at Vanderbilt University, Nashville, TN, USA
| | - Fred S Lamb
- Departments of Pediatrics and Molecular Physiology & Biophysics, Monroe Carell Children's Hospital at Vanderbilt University, Nashville, TN, USA
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14
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Altamura C, Lucchiari S, Sahbani D, Ulzi G, Comi GP, D'Ambrosio P, Petillo R, Politano L, Vercelli L, Mongini T, Dotti MT, Cardani R, Meola G, Lo Monaco M, Matthews E, Hanna MG, Carratù MR, Conte D, Imbrici P, Desaphy JF. The analysis of myotonia congenita mutations discloses functional clusters of amino acids within the CBS2 domain and the C-terminal peptide of the ClC-1 channel. Hum Mutat 2018; 39:1273-1283. [PMID: 29935101 DOI: 10.1002/humu.23581] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 11/10/2022]
Abstract
Myotonia congenita (MC) is a skeletal-muscle hyperexcitability disorder caused by loss-of-function mutations in the ClC-1 chloride channel. Mutations are scattered over the entire sequence of the channel protein, with more than 30 mutations located in the poorly characterized cytosolic C-terminal domain. In this study, we characterized, through patch clamp, seven ClC-1 mutations identified in patients affected by MC of various severities and located in the C-terminal region. The p.Val829Met, p.Thr832Ile, p.Val851Met, p.Gly859Val, and p.Leu861Pro mutations reside in the CBS2 domain, while p.Pro883Thr and p.Val947Glu are in the C-terminal peptide. We showed that the functional properties of mutant channels correlated with the clinical phenotypes of affected individuals. In addition, we defined clusters of ClC-1 mutations within CBS2 and C-terminal peptide subdomains that share the same functional defect: mutations between 829 and 835 residues and in residue 883 induced an alteration of voltage dependence, mutations between 851 and 859 residues, and in residue 947 induced a reduction of chloride currents, whereas mutations on 861 residue showed no obvious change in ClC-1 function. This study improves our understanding of the mechanisms underlying MC, sheds light on the role of the C-terminal region in ClC-1 function, and provides information to develop new antimyotonic drugs.
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Affiliation(s)
- Concetta Altamura
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Sabrina Lucchiari
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy.,Neurology Unit, IRCCS Fondazione Ca' Grande Ospedale Maggiore Policlinico, Milan, Italy
| | - Dalila Sahbani
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Gianna Ulzi
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy.,Neurology Unit, IRCCS Fondazione Ca' Grande Ospedale Maggiore Policlinico, Milan, Italy
| | - Giacomo P Comi
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy.,Neurology Unit, IRCCS Fondazione Ca' Grande Ospedale Maggiore Policlinico, Milan, Italy
| | - Paola D'Ambrosio
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania, Naples, Italy
| | - Roberta Petillo
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania, Naples, Italy
| | - Luisa Politano
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania, Naples, Italy
| | - Liliana Vercelli
- Neuromuscular Unit, Department of Neurosciences, Hospital Città della Salute e della Scienza of Torino, University of Torino, Turin, Italy
| | - Tiziana Mongini
- Neuromuscular Unit, Department of Neurosciences, Hospital Città della Salute e della Scienza of Torino, University of Torino, Turin, Italy
| | - Maria Teresa Dotti
- Unit of Neurology and Neurometabolic Disorders, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, Milan, Italy
| | - Giovanni Meola
- Department of Biomedical Sciences for Health, University of Milan, IRCCS Policlinico San Donato, Milan, Italy
| | - Mauro Lo Monaco
- Institute of Neurology, Catholic University of Sacred Heart, Polyclinic Gemelli, Rome, Italy.,MiA Onlus ("Miotonici in Associazione"), Portici, Italy
| | - Emma Matthews
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Michael G Hanna
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK
| | - Maria Rosaria Carratù
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Polyclinic, Bari, Italy
| | - Diana Conte
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Polyclinic, Bari, Italy
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15
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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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16
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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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17
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Regulatory Conformational Coupling between CLC Anion Channel Membrane and Cytoplasmic Domains. Biophys J 2017; 111:1887-1896. [PMID: 27806270 DOI: 10.1016/j.bpj.2016.09.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 08/30/2016] [Accepted: 09/23/2016] [Indexed: 12/23/2022] Open
Abstract
CLC anion channels are homodimeric proteins. Each subunit is comprised of 18 α-helices designated "A-R" and an intracellular carboxy-terminus containing two cystathionine-β-synthase (CBS1 and CBS2) domains. Conformational coupling between membrane and intracellular domains via poorly understood mechanisms is required for CLC regulation. The activity of the C. elegans CLC channel CLH-3b is reduced by phosphorylation of a carboxy-terminus "activation domain," which disrupts its interaction with CBS domains. CBS2 interfaces with a short intracellular loop, the H-I loop, connecting membrane helices H and I. Alanine mutation of a conserved H-I loop tyrosine residue, Y232, prevents regulation demonstrating that the loop functions to couple phosphorylation-dependent CBS domain conformational changes to channel membrane domains. To gain further insight into the mechanisms of this coupling, we mutated conserved amino acid residues in membrane helices H and I. Only mutation of the H-helix valine residue V228 to leucine prevented phosphorylation-dependent channel regulation. Structural and functional studies of other CLC proteins suggest that V228 may interact with Y529, a conserved R-helix tyrosine residue that forms part of the CLC ion conduction pathway. Mutation of Y529 to alanine also prevented CLH-3b regulation. Intracellular application of the sulfhydryl reactive reagent MTSET using CLH-3b channels engineered with single-cysteine residues in CBS2 indicate that V228L, Y529A, and Y232A disrupt putative regulatory intracellular conformational changes. Extracellular Zn2+ inhibits CLH-3b and alters the effects of intracellular MTSET on channel activity. The effects of Zn2+ are disrupted by V228L, Y529A, and Y232A. Collectively, our findings indicate that there is conformational coupling between CBS domains and the H and R membrane helices mediated by the H-I loop. We propose a simple model by which conformational changes in H and R helices mediate CLH-3b regulation by activation domain phosphorylation.
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18
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Poroca DR, Pelis RM, Chappe VM. ClC Channels and Transporters: Structure, Physiological Functions, and Implications in Human Chloride Channelopathies. Front Pharmacol 2017; 8:151. [PMID: 28386229 PMCID: PMC5362633 DOI: 10.3389/fphar.2017.00151] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/09/2017] [Indexed: 02/04/2023] Open
Abstract
The discovery of ClC proteins at the beginning of the 1990s was important for the development of the Cl- transport research field. ClCs form a large family of proteins that mediate voltage-dependent transport of Cl- ions across cell membranes. They are expressed in both plasma and intracellular membranes of cells from almost all living organisms. ClC proteins form transmembrane dimers, in which each monomer displays independent ion conductance. Eukaryotic members also possess a large cytoplasmic domain containing two CBS domains, which are involved in transport modulation. ClC proteins function as either Cl- channels or Cl-/H+ exchangers, although all ClC proteins share the same basic architecture. ClC channels have two gating mechanisms: a relatively well-studied fast gating mechanism, and a slow gating mechanism, which is poorly defined. ClCs are involved in a wide range of physiological processes, including regulation of resting membrane potential in skeletal muscle, facilitation of transepithelial Cl- reabsorption in kidneys, and control of pH and Cl- concentration in intracellular compartments through coupled Cl-/H+ exchange mechanisms. Several inherited diseases result from C1C gene mutations, including myotonia congenita, Bartter's syndrome (types 3 and 4), Dent's disease, osteopetrosis, retinal degeneration, and lysosomal storage diseases. This review summarizes general features, known or suspected, of ClC structure, gating and physiological functions. We also discuss biophysical properties of mammalian ClCs that are directly involved in the pathophysiology of several human inherited disorders, or that induce interesting phenotypes in animal models.
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Affiliation(s)
- Diogo R Poroca
- Department of Physiology and Biophysics, Dalhousie University, Halifax NS, Canada
| | - Ryan M Pelis
- Department of Pharmacology, Dalhousie University, Halifax NS, Canada
| | - Valérie M Chappe
- Department of Physiology and Biophysics, Dalhousie University, Halifax NS, Canada
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19
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Vien M, Basilio D, Leisle L, Accardi A. Probing the conformation of a conserved glutamic acid within the Cl - pathway of a CLC H +/Cl - exchanger. J Gen Physiol 2017; 149:523-529. [PMID: 28246117 PMCID: PMC5379918 DOI: 10.1085/jgp.201611682] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 12/06/2016] [Accepted: 01/24/2017] [Indexed: 12/17/2022] Open
Abstract
A conserved glutamic acid residue is thought to occupy three different conformations in the transport pathway of CLC H+/Cl− exchangers. Vien et al. provide functional evidence that the most central of these three positions is adopted by CLC-ec1 during transport and is stabilized by hydrogen bonds. The CLC proteins form a broad family of anion-selective transport proteins that includes both channels and exchangers. Despite extensive structural, functional, and computational studies, the transport mechanism of the CLC exchangers remains poorly understood. Several transport models have been proposed but have failed to capture all the key features of these transporters. Multiple CLC crystal structures have suggested that a conserved glutamic acid, Gluex, can adopt three conformations and that the interconversion of its side chain between these states underlies H+/Cl− exchange. One of these states, in which Gluex occupies the central binding site (Scen) while Cl− ions fill the internal and external sites (Sint and Sext), has only been observed in one homologue, the eukaryotic cmCLC. The existence of such a state in other CLCs has not been demonstrated. In this study, we find that during transport, the prototypical prokaryotic CLC exchanger, CLC-ec1, adopts a conformation with functional characteristics that match those predicted for a cmCLC-like state, with Gluex trapped in Scen between two Cl− ions. Transport by CLC-ec1 is reduced when [Cl−] is symmetrically increased on both sides of the membrane and mutations that disrupt the hydrogen bonds stabilizing Gluex in Scen destabilize this trapped state. Furthermore, inhibition of transport by high [Cl−] is abolished in the E148A mutant, in which the Gluex side chain is removed. Collectively, our results suggest that, during the CLC transport cycle, Gluex can occupy Scen as well as the Sext position in which it has been captured crystallographically and that hydrogen bonds with the side chains of residues that coordinate ion binding to Scen play a role in determining the equilibrium between these two conformations.
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Affiliation(s)
- Malvin Vien
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10021
| | - Daniel Basilio
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10021
| | - Lilia Leisle
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10021
| | - Alessio Accardi
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY 10021 .,Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10021.,Department of Biochemistry, Weill Cornell Medical College, New York, NY 10021
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20
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Yu Y, Tsai MF, Yu WP, Chen TY. Modulation of the slow/common gating of CLC channels by intracellular cadmium. ACTA ACUST UNITED AC 2017; 146:495-508. [PMID: 26621774 PMCID: PMC4664824 DOI: 10.1085/jgp.201511413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cd2+ binding to the CLC channel dimer interface inhibits slow gating by altering subunit interactions. Members of the CLC family of Cl− channels and transporters are homodimeric integral membrane proteins. Two gating mechanisms control the opening and closing of Cl− channels in this family: fast gating, which regulates opening and closing of the individual pores in each subunit, and slow (or common) gating, which simultaneously controls gating of both subunits. Here, we found that intracellularly applied Cd2+ reduces the current of CLC-0 because of its inhibition on the slow gating. We identified CLC-0 residues C229 and H231, located at the intracellular end of the transmembrane domain near the dimer interface, as the Cd2+-coordinating residues. The inhibition of the current of CLC-0 by Cd2+ was greatly enhanced by mutation of I225W and V490W at the dimer interface. Biochemical experiments revealed that formation of a disulfide bond within this Cd2+-binding site is also affected by mutation of I225W and V490W, indicating that these two mutations alter the structure of the Cd2+-binding site. Kinetic studies showed that Cd2+ inhibition appears to be state dependent, suggesting that structural rearrangements may occur in the CLC dimer interface during Cd2+ modulation. Mutations of I290 and I556 of CLC-1, which correspond to I225 and V490 of CLC-0, respectively, have been shown previously to cause malfunction of CLC-1 Cl− channel by altering the common gating. Our experimental results suggest that mutations of the corresponding residues in CLC-0 change the subunit interaction and alter the slow gating of CLC-0. The effect of these mutations on modulations of slow gating of CLC channels by intracellular Cd2+ likely depends on their alteration of subunit interactions.
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Affiliation(s)
- Yawei Yu
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
| | - Ming-Feng Tsai
- Department of Biochemistry, Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02453
| | - Wei-Ping Yu
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
| | - Tsung-Yu Chen
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
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Pedersen TH, Riisager A, de Paoli FV, Chen TY, Nielsen OB. Role of physiological ClC-1 Cl- ion channel regulation for the excitability and function of working skeletal muscle. ACTA ACUST UNITED AC 2016; 147:291-308. [PMID: 27022190 PMCID: PMC4810071 DOI: 10.1085/jgp.201611582] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/07/2016] [Indexed: 12/13/2022]
Abstract
Electrical membrane properties of skeletal muscle fibers have been thoroughly studied over the last five to six decades. This has shown that muscle fibers from a wide range of species, including fish, amphibians, reptiles, birds, and mammals, are all characterized by high resting membrane permeability for Cl− ions. Thus, in resting human muscle, ClC-1 Cl− ion channels account for ∼80% of the membrane conductance, and because active Cl− transport is limited in muscle fibers, the equilibrium potential for Cl− lies close to the resting membrane potential. These conditions—high membrane conductance and passive distribution—enable ClC-1 to conduct membrane current that inhibits muscle excitability. This depressing effect of ClC-1 current on muscle excitability has mostly been associated with skeletal muscle hyperexcitability in myotonia congenita, which arises from loss-of-function mutations in the CLCN1 gene. However, given that ClC-1 must be drastically inhibited (∼80%) before myotonia develops, more recent studies have explored whether acute and more subtle ClC-1 regulation contributes to controlling the excitability of working muscle. Methods were developed to measure ClC-1 function with subsecond temporal resolution in action potential firing muscle fibers. These and other techniques have revealed that ClC-1 function is controlled by multiple cellular signals during muscle activity. Thus, onset of muscle activity triggers ClC-1 inhibition via protein kinase C, intracellular acidosis, and lactate ions. This inhibition is important for preserving excitability of working muscle in the face of activity-induced elevation of extracellular K+ and accumulating inactivation of voltage-gated sodium channels. Furthermore, during prolonged activity, a marked ClC-1 activation can develop that compromises muscle excitability. Data from ClC-1 expression systems suggest that this ClC-1 activation may arise from loss of regulation by adenosine nucleotides and/or oxidation. The present review summarizes the current knowledge of the physiological factors that control ClC-1 function in active muscle.
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Affiliation(s)
| | - Anders Riisager
- Department of Biomedicine, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Tsung-Yu Chen
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
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22
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Seong JY, Ha K, Hong C, Myeong J, Lim HH, Yang D, So I. Helix O modulates voltage dependency of CLC-1. Pflugers Arch 2016; 469:183-193. [PMID: 27921211 DOI: 10.1007/s00424-016-1907-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 10/14/2016] [Accepted: 11/14/2016] [Indexed: 11/25/2022]
Abstract
The chloride channel (CLC) family of proteins consists of channels and transporters that share similarities in architecture and play essential roles in physiological functions. Among the CLC family, CLC-1 channels have the representative homodimeric double-barreled structure carrying two gating processes. One is protopore gating that acts on each pore independently by glutamate residue (Eext). The other is common gating that closes both pores simultaneously in association with large conformational changes across each subunit. In skeletal muscle, CLC-1 is associated with maintaining normal sarcolemmal excitability, and a number of myotonic mutants were reported to modify the channel gating of CLC-1. In this study, we characterized highly conserved helix O as a key determinant of structural stability in CLC-1. Supporting this hypothesis, myotonic mutant (G523D) at N-terminal of helix O showed the activation at hyperpolarizing membrane potentials with a reversed voltage dependency. However, introducing glutamate at serine residue (S537) at the C-terminal of the helix O on G523D restored WT-like voltage dependency of the common gate and showed proton insensitive voltage dependency. To further validate this significant site, site-specific mutagenesis experiments was performed on V292 that is highly conserved as glutamate in antiporter and closely located to S537 and showed that this area is essential for channel function. Taken together, the results of our study suggest the importance of helix O as the main contributor for stable structure of evolutionary conserved CLC proteins and its key role in voltage dependency of the CLC-1. Furthermore, the C-terminal of the helix O can offer a clue for possible proton involvement in CLC-1 channel.
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Affiliation(s)
- Ju Yong Seong
- Department of Physiology, Seoul National University, College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Kotdaji Ha
- Department of Physiology, Seoul National University, College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Chansik Hong
- Department of Physiology, Seoul National University, College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Jongyun Myeong
- Department of Physiology, Seoul National University, College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul, 110-799, Republic of Korea
| | - Hyun-Ho Lim
- Korea Brain Research Institute (KBRI), Daegu, 41068, Republic of Korea
| | - Dongki Yang
- Department of Physiology, College of Medicine, Gachon University, Incheon, 461-701, Republic of Korea
| | - Insuk So
- Department of Physiology, Seoul National University, College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul, 110-799, Republic of Korea.
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23
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Imbrici P, Altamura C, Camerino GM, Mangiatordi GF, Conte E, Maggi L, Brugnoni R, Musaraj K, Caloiero R, Alberga D, Marsano RM, Ricci G, Siciliano G, Nicolotti O, Mora M, Bernasconi P, Desaphy JF, Mantegazza R, Camerino DC. Multidisciplinary study of a new ClC-1 mutation causing myotonia congenita: a paradigm to understand and treat ion channelopathies. FASEB J 2016; 30:3285-3295. [PMID: 27324117 PMCID: PMC5024700 DOI: 10.1096/fj.201500079r] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 06/07/2016] [Indexed: 11/11/2022]
Abstract
Myotonia congenita is an inherited disease that is characterized by impaired muscle relaxation after contraction caused by loss-of-function mutations in the skeletal muscle ClC-1 channel. We report a novel ClC-1 mutation, T335N, that is associated with a mild phenotype in 1 patient, located in the extracellular I-J loop. The purpose of this study was to provide a solid correlation between T335N dysfunction and clinical symptoms in the affected patient as well as to offer hints for drug development. Our multidisciplinary approach includes patch-clamp electrophysiology on T335N and ClC-1 wild-type channels expressed in tsA201 cells, Western blot and quantitative PCR analyses on muscle biopsies from patient and unaffected individuals, and molecular dynamics simulations using a homology model of the ClC-1 dimer. T335N channels display reduced chloride currents as a result of gating alterations rather than altered surface expression. Molecular dynamics simulations suggest that the I-J loop might be involved in conformational changes that occur at the dimer interface, thus affecting gating. Finally, the gene expression profile of T335N carrier showed a diverse expression of K+ channel genes, compared with control individuals, as potentially contributing to the phenotype. This experimental paradigm satisfactorily explained myotonia in the patient. Furthermore, it could be relevant to the study and therapy of any channelopathy.-Imbrici, P., Altamura, C., Camerino, G. M., Mangiatordi, G. F., Conte, E., Maggi, L., Brugnoni, R., Musaraj, K., Caloiero, R., Alberga, D., Marsano, R. M., Ricci, G., Siciliano, G., Nicolotti, O., Mora, M., Bernasconi, P., Desaphy, J.-F., Mantegazza, R., Camerino, D. C. Multidisciplinary study of a new ClC-1 mutation causing myotonia congenita: a paradigm to understand and treat ion channelopathies.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy; paola.imbrici@uniba
| | - Concetta Altamura
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | | | | | - Elena Conte
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Lorenzo Maggi
- Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy
| | - Raffaella Brugnoni
- Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy
| | - Kejla Musaraj
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Roberta Caloiero
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Domenico Alberga
- Department of Physics "M. Merlin," Istituto Nazionale di Fisica Nucleare and Centro di Tecnologie Innovative per la Rilevazione e l'Elaborazione del Segnale, University of Bari "Aldo Moro," Bari, Italy
| | | | - Giulia Ricci
- Department of Clinical and Experimental Medicine, Section of Neurology, University of Pisa, Pisa, Italy
| | - Gabriele Siciliano
- Department of Clinical and Experimental Medicine, Section of Neurology, University of Pisa, Pisa, Italy
| | - Orazio Nicolotti
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
| | - Marina Mora
- Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy
| | - Pia Bernasconi
- Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro," Bari, Italy
| | - Renato Mantegazza
- Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy
| | - Diana Conte Camerino
- Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy
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24
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Riisager A, de Paoli FV, Yu WP, Pedersen TH, Chen TY, Nielsen OB. Protein kinase C-dependent regulation of ClC-1 channels in active human muscle and its effect on fast and slow gating. J Physiol 2016; 594:3391-406. [PMID: 26857341 DOI: 10.1113/jp271556] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/26/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Regulation of ion channel function during repeated firing of action potentials is commonly observed in excitable cells. Recently it was shown that muscle activity is associated with rapid, protein kinase C (PKC)-dependent ClC-1 Cl(-) channel inhibition in rodent muscle. While this PKC-dependent ClC-1 inhibition during muscle activity was shown to be important for the maintenance of contractile endurance in rat muscle it is unknown whether a similar regulation exists in human muscle. Also, the molecular mechanisms underlying the observed PKC-dependent ClC-1 inhibition are unclear. Here we present the first demonstration of ClC-1 inhibition in active human muscle fibres, and we determine the changes in ClC-1 gating that underlie the PKC-dependent ClC-1 inhibition in active muscle using human ClC-1 expressed in Xenopus oocytes. This activity-induced ClC-1 inhibition is suggested to represent a mechanism by which human muscle fibres maintain their excitability during sustained activity. ABSTRACT Repeated firing of action potentials (APs) is known to trigger rapid, protein kinase C (PKC)-dependent inhibition of ClC-1 Cl(-) ion channels in rodent muscle and this inhibition is important for contractile endurance. It is currently unknown whether similar regulation exists in human muscle, and the molecular mechanisms underlying PKC-dependent ClC-1 inhibition are unclear. This study first determined whether PKC-dependent ClC-1 inhibition exists in active human muscle, and second, it clarified how PKC alters the gating of human ClC-1 expressed in Xenopus oocytes. In human abdominal and intercostal muscles, repeated AP firing was associated with 30-60% reduction of ClC-1 function, which could be completely prevented by PKC inhibition (1 μm GF109203X). The role of the PKC-dependent ClC-1 inhibition was evaluated from rheobase currents before and after firing 1000 APs: while rheobase current was well maintained after activity under control conditions it rose dramatically if PKC-dependent ClC-1 inhibition had been prevented with the inhibitor. This demonstrates that the ClC-1 inhibition is important for maintenance of excitability in active human muscle fibres. Oocyte experiments showed that PKC activation lowered the overall open probability of ClC-1 in the voltage range relevant for AP initiation in muscle fibres. More detailed analysis of this reduction showed that PKC mostly affected the slow gate of ClC-1. Indeed, there was no effect of PKC activation in C277S mutated ClC-1 in which the slow gate is effectively locked open. It is concluded that regulation of excitability of active human muscle fibres relies on PKC-dependent ClC-1 inhibition via a gating mechanism.
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Affiliation(s)
- Anders Riisager
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark.,Centre for Neuroscience and Department of Neurology, University of California, Davis, CA, 95618, USA
| | - Frank Vincenzo de Paoli
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark.,Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200, Aarhus N, Denmark
| | - Wei-Ping Yu
- Centre for Neuroscience and Department of Neurology, University of California, Davis, CA, 95618, USA
| | - Thomas Holm Pedersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark
| | - Tsung-Yu Chen
- Centre for Neuroscience and Department of Neurology, University of California, Davis, CA, 95618, USA
| | - Ole Baekgaard Nielsen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, 8000, Aarhus C, Denmark
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25
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Accardi A. Structure and gating of CLC channels and exchangers. J Physiol 2015; 593:4129-38. [PMID: 26148215 DOI: 10.1113/jp270575] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 06/28/2015] [Indexed: 11/08/2022] Open
Abstract
Since their serendipitous discovery the CLC family of Cl(-) transporting proteins has been a never ending source of surprises. From their double-barrelled architecture to their complex structure and divergence as channels and transporters, the CLCs never cease to amaze biophysicists, biochemists and physiologists alike. These unusual functional properties allow the CLCs to fill diverse physiological niches, regulating processes that range from muscle contraction to acidification of intracellular organelles, nutrient accumulation and survival of bacteria to environmental stresses. Over the last 15 years, the availability of atomic-level information on the structure of the CLCs, coupled to the discovery that the family is divided into passive channels and secondary active transporters, has revolutionized our understanding of their function. These breakthroughs led to the identification of the key structural elements regulating gating, transport, selectivity and regulation by ligands. Unexpectedly, many lines of evidence indicate that the CLC exchangers function according to a non-conventional transport mechanism that defies the fundamental tenets of the alternating-access paradigm for exchange transport, paving the way for future unexpected insights into the principles underlying active transport and channel gating.
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Affiliation(s)
- Alessio Accardi
- Departments of Anaesthesiology, Physiology & Biophysics, and Biochemistry, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10021, USA
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26
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Imbrici P, Maggi L, Mangiatordi GF, Dinardo MM, Altamura C, Brugnoni R, Alberga D, Pinter GL, Ricci G, Siciliano G, Micheli R, Annicchiarico G, Lattanzi G, Nicolotti O, Morandi L, Bernasconi P, Desaphy JF, Mantegazza R, Camerino DC. ClC-1 mutations in myotonia congenita patients: insights into molecular gating mechanisms and genotype-phenotype correlation. J Physiol 2015; 593:4181-99. [PMID: 26096614 DOI: 10.1113/jp270358] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 06/04/2015] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Loss-of-function mutations of the skeletal muscle ClC-1 channel cause myotonia congenita with variable phenotypes. Using patch clamp we show that F484L, located in the conducting pore, probably induces mild dominant myotonia by right-shifting the slow gating of ClC-1 channel, without exerting a dominant-negative effect on the wild-type (WT) subunit. Molecular dynamics simulations suggest that F484L affects the slow gate by increasing the frequency and the stability of H-bond formation between E232 in helix F and Y578 in helix R. Three other myotonic ClC-1 mutations are shown to produce distinct effects on channel function: L198P shifts the slow gate to positive potentials, V640G reduces channel activity, while L628P displays a WT-like behaviour (electrophysiology data only). Our results provide novel insight into the molecular mechanisms underlying normal and altered ClC-1 function. ABSTRACT Myotonia congenita is an inherited disease caused by loss-of-function mutations of the skeletal muscle ClC-1 chloride channel, characterized by impaired muscle relaxation after contraction and stiffness. In the present study, we provided an in-depth characterization of F484L, a mutation previously identified in dominant myotonia, in order to define the genotype-phenotype correlation, and to elucidate the contribution of this pore residue to the mechanisms of ClC-1 gating. Patch-clamp recordings showed that F484L reduced chloride currents at every tested potential and dramatically right-shifted the voltage dependence of slow gating, thus contributing to the mild clinical phenotype of affected heterozygote carriers. Unlike dominant mutations located at the dimer interface, no dominant-negative effect was observed when F484L mutant subunits were co-expressed with wild type. Molecular dynamics simulations further revealed that F484L affected the slow gate by increasing the frequency and stability of the H-bond formation between the pore residue E232 and the R helix residue Y578. In addition, using patch-clamp electrophysiology, we characterized three other myotonic ClC-1 mutations. We proved that the dominant L198P mutation in the channel pore also right-shifted the voltage dependence of slow gating, recapitulating mild myotonia. The recessive V640G mutant drastically reduced channel function, which probably accounts for myotonia. In contrast, the recessive L628P mutant produced currents very similar to wild type, suggesting that the occurrence of the compound truncating mutation (Q812X) or other muscle-specific mechanisms accounted for the severe symptoms observed in this family. Our results provide novel insight into the molecular mechanisms underlying normal and altered ClC-1 function.
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Affiliation(s)
- P Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
| | - L Maggi
- Neuroimmunology and Neuromuscular Diseases Unit, IRCCS Fondazione Istituto Neurologico 'Carlo Besta', Milano, Italy
| | - G F Mangiatordi
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
| | - M M Dinardo
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
| | - C Altamura
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
| | - R Brugnoni
- Neuroimmunology and Neuromuscular Diseases Unit, IRCCS Fondazione Istituto Neurologico 'Carlo Besta', Milano, Italy
| | - D Alberga
- Department of Physics 'M. Merlin', INFN and TIRES, University of Bari, Bari, Italy
| | - G Lauria Pinter
- Neuroalgology and Headache Unit, IRCCS Fondazione Istituto Neurologico 'Carlo Besta', Milano, Italy
| | - G Ricci
- Department of Clinical and Experimental Medicine, Section of Neurology, University of Pisa, Pisa, Italy
| | - G Siciliano
- Department of Clinical and Experimental Medicine, Section of Neurology, University of Pisa, Pisa, Italy
| | - R Micheli
- Unit of Child Neurology and Psychiatry, Spedali Civili, Brescia, Italy
| | - G Annicchiarico
- Regional Coordination for Rare Diseases, A. Re. S. Puglia, Bari, Italy
| | - G Lattanzi
- Department of Physics 'M. Merlin', INFN and TIRES, University of Bari, Bari, Italy
| | - O Nicolotti
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
| | - L Morandi
- Neuroimmunology and Neuromuscular Diseases Unit, IRCCS Fondazione Istituto Neurologico 'Carlo Besta', Milano, Italy
| | - P Bernasconi
- Neuroimmunology and Neuromuscular Diseases Unit, IRCCS Fondazione Istituto Neurologico 'Carlo Besta', Milano, Italy
| | - J-F Desaphy
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
| | - R Mantegazza
- Neuroimmunology and Neuromuscular Diseases Unit, IRCCS Fondazione Istituto Neurologico 'Carlo Besta', Milano, Italy
| | - D Conte Camerino
- Department of Pharmacy - Drug Sciences, University of Bari, Bari, Italy
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27
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Imbrici P, Altamura C, Pessia M, Mantegazza R, Desaphy JF, Camerino DC. ClC-1 chloride channels: state-of-the-art research and future challenges. Front Cell Neurosci 2015; 9:156. [PMID: 25964741 PMCID: PMC4410605 DOI: 10.3389/fncel.2015.00156] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/08/2015] [Indexed: 01/06/2023] Open
Abstract
The voltage-dependent ClC-1 chloride channel belongs to the CLC channel/transporter family. It is a homodimer comprising two individual pores which can operate independently or simultaneously according to two gating modes, the fast and the slow gate of the channel. ClC-1 is preferentially expressed in the skeletal muscle fibers where the presence of an efficient Cl(-) homeostasis is crucial for the correct membrane repolarization and propagation of action potential. As a consequence, mutations in the CLCN1 gene cause dominant and recessive forms of myotonia congenita (MC), a rare skeletal muscle channelopathy caused by abnormal membrane excitation, and clinically characterized by muscle stiffness and various degrees of transitory weakness. Elucidation of the mechanistic link between the genetic defects and the disease pathogenesis is still incomplete and, at this time, there is no specific treatment for MC. Still controversial is the subcellular localization pattern of ClC-1 channels in skeletal muscle as well as its modulation by some intracellular factors. The expression of ClC-1 in other tissues such as in brain and heart and the possible assembly of ClC-1/ClC-2 heterodimers further expand the physiological properties of ClC-1 and its involvement in diseases. A recent de novo CLCN1 truncation mutation in a patient with generalized epilepsy indeed postulates an unexpected role of this channel in the control of neuronal network excitability. This review summarizes the most relevant and state-of-the-art research on ClC-1 chloride channels physiology and associated diseases.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari “Aldo Moro”,Bari, Italy
| | - Concetta Altamura
- Department of Pharmacy - Drug Sciences, University of Bari “Aldo Moro”,Bari, Italy
| | - Mauro Pessia
- Department of Pharmacy - Drug Sciences, University of Bari “Aldo Moro”,Bari, Italy
| | - Renato Mantegazza
- Department of Pharmacy - Drug Sciences, University of Bari “Aldo Moro”,Bari, Italy
| | | | - Diana Conte Camerino
- Department of Pharmacy - Drug Sciences, University of Bari “Aldo Moro”,Bari, Italy
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Pusch M, Zifarelli G. ClC-5: Physiological role and biophysical mechanisms. Cell Calcium 2014; 58:57-66. [PMID: 25443653 DOI: 10.1016/j.ceca.2014.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/19/2014] [Accepted: 09/20/2014] [Indexed: 01/05/2023]
Abstract
Cl(-) transport in animal cells has fundamental physiological roles and it is mediated by a variety of protein families, one of them being the CLC family of ion channels and transporters. Besides their physiological relevance, CLC proteins show peculiar biophysical properties. This review will focus on a member of the CLC protein family, the endosomal Cl(-)/H(+) antiporter ClC-5. ClC-5 mutations cause Dent's disease, a renal syndrome due to defective protein reabsorption in the proximal tubule. This established the critical function of ClC-5 for endocytosis. However, our understanding of ClC-5's molecular role in endosomes and of its biophysical properties has proved elusive in spite of important progress achieved in the last two decades. Early models in which ClC-5 would provide a shunt conductance to enable efficient endosomal acidification conflicted with the antiport activity of ClC-5 that has more recently emerged. Currently, the physiological role of ClC-5 is hotly debated and its biophysical properties are still not fully understood.
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Affiliation(s)
- Michael Pusch
- Istituto di Biofisica, CNR, Via De Marini 6, 16149 Genoa, Italy
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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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Conformational changes required for H(+)/Cl(-) exchange mediated by a CLC transporter. Nat Struct Mol Biol 2014; 21:456-63. [PMID: 24747941 PMCID: PMC4040230 DOI: 10.1038/nsmb.2814] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 03/26/2014] [Indexed: 11/08/2022]
Abstract
CLC-type exchangers mediate transmembrane Cl(-) transport. Mutations altering their gating properties cause numerous genetic disorders. However, their transport mechanism remains poorly understood. In conventional models, two gates alternatively expose substrates to the intra- or extracellular solutions. A glutamate was identified as the only gate in the CLCs, suggesting that CLCs function by a nonconventional mechanism. Here we show that transport in CLC-ec1, a prokaryotic homolog, is inhibited by cross-links constraining movement of helix O far from the transport pathway. Cross-linked CLC-ec1 adopts a wild-type-like structure, indicating stabilization of a native conformation. Movements of helix O are transduced to the ion pathway via a direct contact between its C terminus and a tyrosine that is a constitutive element of the second gate of CLC transporters. Therefore, the CLC exchangers have two gates that are coupled through conformational rearrangements outside the ion pathway.
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ClC-1 and ClC-2 form hetero-dimeric channels with novel protopore functions. Pflugers Arch 2014; 466:2191-204. [DOI: 10.1007/s00424-014-1490-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 02/19/2014] [Indexed: 10/25/2022]
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Pusch M, Zifarelli G. Thermal sensitivity of CLC and TMEM16 chloride channels and transporters. CURRENT TOPICS IN MEMBRANES 2014; 74:213-31. [PMID: 25366238 DOI: 10.1016/b978-0-12-800181-3.00008-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cl(-) transport is of fundamental importance in the most diverse physiological contexts and it is mediated by a variety of ion channels and transporters belonging to different protein families. In particular, the recently identified TMEM16 protein family comprises the long sought Ca(2+)-activated Cl(-) channel (CaCC) and the activity of one of its members, TMEM16A, is highly dependent on temperature and is involved in thermal nociception. Among the other protein families mediating Cl(-) transport, CLC proteins are also regulated by temperature although so far the physiological implications of this dependence are unknown.
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