1
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Stringer RN, Weiss N. Pathophysiology of ion channels in amyotrophic lateral sclerosis. Mol Brain 2023; 16:82. [PMID: 38102715 PMCID: PMC10722804 DOI: 10.1186/s13041-023-01070-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 12/11/2023] [Indexed: 12/17/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) stands as the most prevalent and severe form of motor neuron disease, affecting an estimated 2 in 100,000 individuals worldwide. It is characterized by the progressive loss of cortical, brainstem, and spinal motor neurons, ultimately resulting in muscle weakness and death. Although the etiology of ALS remains poorly understood in most cases, the remodelling of ion channels and alteration in neuronal excitability represent a hallmark of the disease, manifesting not only during the symptomatic period but also in the early pre-symptomatic stages. In this review, we delve into these alterations observed in ALS patients and preclinical disease models, and explore their consequences on neuronal activities. Furthermore, we discuss the potential of ion channels as therapeutic targets in the context of ALS.
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Affiliation(s)
- Robin N Stringer
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Norbert Weiss
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic.
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia.
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2
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Brenes O, Pusch M, Morales F. ClC-1 Chloride Channel: Inputs on the Structure-Function Relationship of Myotonia Congenita-Causing Mutations. Biomedicines 2023; 11:2622. [PMID: 37892996 PMCID: PMC10604815 DOI: 10.3390/biomedicines11102622] [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: 07/24/2023] [Revised: 08/11/2023] [Accepted: 08/24/2023] [Indexed: 10/29/2023] Open
Abstract
Myotonia congenita is a hereditary muscle disease mainly characterized by muscle hyperexcitability, which leads to a sustained burst of discharges that correlates with the magnitude and duration of involuntary aftercontractions, muscle stiffness, and hypertrophy. Mutations in the chloride voltage-gated channel 1 (CLCN1) gene that encodes the skeletal muscle chloride channel (ClC-1) are responsible for this disease, which is commonly known as myotonic chloride channelopathy. The biophysical properties of the mutated channel have been explored and analyzed through in vitro approaches, providing important clues to the general function/dysfunction of the wild-type and mutated channels. After an exhaustive search for CLCN1 mutations, we report in this review more than 350 different mutations identified in the literature. We start discussing the physiological role of the ClC-1 channel in skeletal muscle functioning. Then, using the reported functional effects of the naturally occurring mutations, we describe the biophysical and structural characteristics of the ClC-1 channel to update the knowledge of the function of each of the ClC-1 helices, and finally, we attempt to point out some patterns regarding the effects of mutations in the different helices and loops of the protein.
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Affiliation(s)
- Oscar Brenes
- Departamento de Fisiología, Escuela de Medicina, Universidad de Costa Rica, San José 11501-2060, Costa Rica;
- Centro de Investigación en Neurociencias (CIN), Universidad de Costa Rica, San José 11501-2060, Costa Rica
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche (CNR), Via De Marini 6, 16149 Genova, Italy
| | - Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José 11501-2060, Costa Rica
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3
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Vacchiano V, Brugnoni R, Campanale C, Imbrici P, Dinoi G, Canioni E, Laghetti P, Saltarella I, Altamura C, Maggi L, Liguori R, Donadio V, Desaphy JF. Coexistence of SCN4A and CLCN1 mutations in a family with atypical myotonic features: A clinical and functional study. Exp Neurol 2023; 362:114342. [PMID: 36720299 DOI: 10.1016/j.expneurol.2023.114342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 01/12/2023] [Accepted: 01/26/2023] [Indexed: 01/30/2023]
Abstract
Non-dystrophic myotonias include several entities with possible clinical overlap, i.e. myotonia congenita caused by CLCN1 gene mutations, as well as paramyotonia congenita and sodium channel myotonia caused by SCN4A gene mutations. Herein, we describe the clinical features of five relatives affected by clinical and neurophysiological myotonia, with an aspecific and mixed phenotype. Next-generation sequencing identified the novel p.K1302R variant in SCN4A and the p.H838P variant in CLCN1. Segregation of the two mutations with the disease was confirmed by genotyping affected and non-affected family members. Patch-clamp experiments showed that sodium currents generated by p.K1302R and WT hNav1.4 were very similar. Mutant channel showed a small negative shift (5 mV) in the voltage-dependence of activation, which increased the likelihood of the channel to open at more negative voltages. The p.H838P mutation caused a reduction in chloride current density and a small voltage-dependence shift towards less negative potentials, in agreement with its position into the CBS2 domain of the C-terminus. Our results demonstrated that the mild functional alterations induced by p.K1302R and p.H838P in combination may be responsible for the mixed myotonic phenotypes. The K1302R mutant was sensitive to mexiletine and lamotrigine, suggesting that both drugs might be useful for the K1302R carriers.
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Affiliation(s)
- Veria Vacchiano
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy.
| | - Raffaella Brugnoni
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Carmen Campanale
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Dept. of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Giorgia Dinoi
- Dept. of Pharmacy - Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Eleonora Canioni
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Paola Laghetti
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Ilaria Saltarella
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Lorenzo Maggi
- Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Italy
| | - Rocco Liguori
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Vincenzo Donadio
- IRCSS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Jean-François Desaphy
- Dept. of Precision and Regenerative Medicine, School of Medicine, University of Bari Aldo Moro, Bari, Italy
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4
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Al-Sabri MH, Behare N, Alsehli AM, Berkins S, Arora A, Antoniou E, Moysiadou EI, Anantha-Krishnan S, Cosmen PD, Vikner J, Moulin TC, Ammar N, Boukhatmi H, Clemensson LE, Rask-Andersen M, Mwinyi J, Williams MJ, Fredriksson R, Schiöth HB. Statins Induce Locomotion and Muscular Phenotypes in Drosophila melanogaster That Are Reminiscent of Human Myopathy: Evidence for the Role of the Chloride Channel Inhibition in the Muscular Phenotypes. Cells 2022; 11:3528. [PMID: 36428957 PMCID: PMC9688544 DOI: 10.3390/cells11223528] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/17/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022] Open
Abstract
The underlying mechanisms for statin-induced myopathy (SIM) are still equivocal. In this study, we employ Drosophila melanogaster to dissect possible underlying mechanisms for SIM. We observe that chronic fluvastatin treatment causes reduced general locomotion activity and climbing ability. In addition, transmission microscopy of dissected skeletal muscles of fluvastatin-treated flies reveals strong myofibrillar damage, including increased sarcomere lengths and Z-line streaming, which are reminiscent of myopathy, along with fragmented mitochondria of larger sizes, most of which are round-like shapes. Furthermore, chronic fluvastatin treatment is associated with impaired lipid metabolism and insulin signalling. Mechanistically, knockdown of the statin-target Hmgcr in the skeletal muscles recapitulates fluvastatin-induced mitochondrial phenotypes and lowered general locomotion activity; however, it was not sufficient to alter sarcomere length or elicit myofibrillar damage compared to controls or fluvastatin treatment. Moreover, we found that fluvastatin treatment was associated with reduced expression of the skeletal muscle chloride channel, ClC-a (Drosophila homolog of CLCN1), while selective knockdown of skeletal muscle ClC-a also recapitulated fluvastatin-induced myofibril damage and increased sarcomere lengths. Surprisingly, exercising fluvastatin-treated flies restored ClC-a expression and normalized sarcomere lengths, suggesting that fluvastatin-induced myofibrillar phenotypes could be linked to lowered ClC-a expression. Taken together, these results may indicate the potential role of ClC-a inhibition in statin-associated muscular phenotypes. This study underlines the importance of Drosophila melanogaster as a powerful model system for elucidating the locomotion and muscular phenotypes, promoting a better understanding of the molecular mechanisms underlying SIM.
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Affiliation(s)
- Mohamed H. Al-Sabri
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
- Department of Pharmaceutical Biosciences, Uppsala University, 751 24 Uppsala, Sweden
| | - Neha Behare
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Ahmed M. Alsehli
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
- Faculty of Medicine, King Abdulaziz University and Hospital, Al Ehtifalat St., Jeddah 21589, Saudi Arabia
| | - Samuel Berkins
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Aadeya Arora
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Eirini Antoniou
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Eleni I. Moysiadou
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Sowmya Anantha-Krishnan
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Patricia D. Cosmen
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Johanna Vikner
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Thiago C. Moulin
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
- Faculty of Medicine, Department of Experimental Medical Science, Lund University, Sölvegatan 19, BMC F10, 221 84 Lund, Sweden
| | - Nourhene Ammar
- Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes, CNRS, UMR6290, 35065 Rennes, France
| | - Hadi Boukhatmi
- Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes, CNRS, UMR6290, 35065 Rennes, France
| | - Laura E. Clemensson
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Mathias Rask-Andersen
- Department of Immunology, Genetics and Pathology, Uppsala University, 752 37 Uppsala, Sweden
| | - Jessica Mwinyi
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Michael J. Williams
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
| | - Robert Fredriksson
- Department of Pharmaceutical Biosciences, Uppsala University, 751 24 Uppsala, Sweden
| | - Helgi B. Schiöth
- Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Biomedical Center (BMC), Uppsala University, Husargatan 3, 751 24 Uppsala, Sweden
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5
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Altamura C, Conte E, Campanale C, Laghetti P, Saltarella I, Camerino GM, Imbrici P, Desaphy JF. Chaperone activity of niflumic acid on ClC-1 chloride channel mutants causing myotonia congenita. Front Pharmacol 2022; 13:958196. [PMID: 36034862 PMCID: PMC9403836 DOI: 10.3389/fphar.2022.958196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/08/2022] [Indexed: 11/14/2022] Open
Abstract
Myotonia congenita (MC) is an inherited rare disease characterized by impaired muscle relaxation after contraction, resulting in muscle stiffness. It is caused by loss-of-function mutations in the skeletal muscle chloride channel ClC-1, important for the stabilization of resting membrane potential and for the repolarization phase of action potentials. Thanks to in vitro functional studies, the molecular mechanisms by which ClC-1 mutations alter chloride ion influx into the cell have been in part clarified, classifying them in “gating-defective” or “expression-defective” mutations. To date, the treatment of MC is only palliative because no direct ClC-1 activator is available. An ideal drug should be one which is able to correct biophysical defects of ClC-1 in the case of gating-defective mutations or a drug capable to recover ClC-1 protein expression on the plasma membrane for trafficking-defective ones. In this study, we tested the ability of niflumic acid (NFA), a commercial nonsteroidal anti-inflammatory drug, to act as a pharmacological chaperone on trafficking-defective MC mutants (A531V, V947E). Wild-type (WT) or MC mutant ClC-1 channels were expressed in HEK293 cells and whole-cell chloride currents were recorded with the patch-clamp technique before and after NFA incubation. Membrane biotinylation assays and western blot were performed to support electrophysiological results. A531V and V947E mutations caused a decrease in chloride current density due to a reduction of ClC-1 total protein level and channel expression on the plasma membrane. The treatment of A531V and V947E-transfected cells with 50 µM NFA restored chloride currents, reaching levels similar to those of WT. Furthermore, no significant difference was observed in voltage dependence, suggesting that NFA increased protein membrane expression without altering the function of ClC-1. Indeed, biochemical experiments confirmed that V947E total protein expression and its plasma membrane distribution were recovered after NFA incubation, reaching protein levels similar to WT. Thus, the use of NFA as a pharmacological chaperone in trafficking defective ClC-1 channel mutations could represent a good strategy in the treatment of MC. Because of the favorable safety profile of this drug, our study may easily open the way for confirmatory human pilot studies aimed at verifying the antimyotonic activity of NFA in selected patients carrying specific ClC-1 channel mutations.
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Affiliation(s)
- Concetta Altamura
- Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
- *Correspondence: Concetta Altamura,
| | - Elena Conte
- Dept. of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Carmen Campanale
- Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Paola Laghetti
- Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Ilaria Saltarella
- Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | | | - Paola Imbrici
- Dept. of Pharmacy-Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Jean-François Desaphy
- Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
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6
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Genetic spectrum and founder effect of non-dystrophic myotonia: a Japanese case series study. J Neurol 2022; 269:6406-6415. [PMID: 35907044 DOI: 10.1007/s00415-022-11305-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 10/16/2022]
Abstract
Non-dystrophic myotonias (NDM) are rare skeletal muscle channelopathies, mainly linked to two voltage-gated ion channel genes, CLCN1 and SCN4A. The aim of this study is to identify the clinical and genetic features of patients with NDM in Japan. We collected a Japanese nationwide case series of patients with clinical diagnosis of NDM (1999-2021). Among 71 out of 88 pedigrees, using Sanger and next-generation sequencing targeting both CLCN1 and SCN4A genes, variants classified as pathogenic/likely pathogenic/unknown significance were detected from CLCN1 (31 probands), SCN4A (36 probands), or both genes (4 probands), and 11 of them were novel. Pedigrees carrying mono-allelic CLCN1 variants were more commonly seen than that with bi-allelic/double variants (24:7). Compared to patients with CLCN1 variants, patients harboring SCN4A variants showed younger onset age (5.64 ± 4.70 years vs. 9.23 ± 5.21 years), fewer warm-up phenomenon, but more paramyotonia, hyperCKemia, transient muscle weakness, and cold-induced myotonia. Haplotype analysis verified founder effects of the hot spot variants in both CLCN1 (p.T539A) and SCN4A (p.T1313M). This study reveals variants in CLCN1 and SCN4A from 80.7% of our case series, extending genetic spectrum of NDM, and would further our understanding of clinical similarity/diversity between CLCN1- and SCN4A-related NDM, as well as the genetic racial differences.
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7
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Tarantino N, Canfora I, Camerino GM, Pierno S. Therapeutic Targets in Amyotrophic Lateral Sclerosis: Focus on Ion Channels and Skeletal Muscle. Cells 2022; 11:cells11030415. [PMID: 35159225 PMCID: PMC8834084 DOI: 10.3390/cells11030415] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/18/2022] [Accepted: 01/22/2022] [Indexed: 02/04/2023] Open
Abstract
Amyotrophic Lateral Sclerosis is a neurodegenerative disease caused by progressive loss of motor neurons, which severely compromises skeletal muscle function. Evidence shows that muscle may act as a molecular powerhouse, whose final signals generate in patients a progressive loss of voluntary muscle function and weakness leading to paralysis. This pathology is the result of a complex cascade of events that involves a crosstalk among motor neurons, glia, and muscles, and evolves through the action of converging toxic mechanisms. In fact, mitochondrial dysfunction, which leads to oxidative stress, is one of the mechanisms causing cell death. It is a common denominator for the two existing forms of the disease: sporadic and familial. Other factors include excitotoxicity, inflammation, and protein aggregation. Currently, there are limited cures. The only approved drug for therapy is riluzole, that modestly prolongs survival, with edaravone now waiting for new clinical trial aimed to clarify its efficacy. Thus, there is a need of effective treatments to reverse the damage in this devastating pathology. Many drugs have been already tested in clinical trials and are currently under investigation. This review summarizes the already tested drugs aimed at restoring muscle-nerve cross-talk and on new treatment options targeting this tissue.
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8
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Maggi L, Bonanno S, Altamura C, Desaphy JF. Ion Channel Gene Mutations Causing Skeletal Muscle Disorders: Pathomechanisms and Opportunities for Therapy. Cells 2021; 10:cells10061521. [PMID: 34208776 PMCID: PMC8234207 DOI: 10.3390/cells10061521] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/03/2021] [Accepted: 06/10/2021] [Indexed: 02/06/2023] Open
Abstract
Skeletal muscle ion channelopathies (SMICs) are a large heterogeneous group of rare genetic disorders caused by mutations in genes encoding ion channel subunits in the skeletal muscle mainly characterized by myotonia or periodic paralysis, potentially resulting in long-term disabilities. However, with the development of new molecular technologies, new genes and new phenotypes, including progressive myopathies, have been recently discovered, markedly increasing the complexity in the field. In this regard, new advances in SMICs show a less conventional role of ion channels in muscle cell division, proliferation, differentiation, and survival. Hence, SMICs represent an expanding and exciting field. Here, we review current knowledge of SMICs, with a description of their clinical phenotypes, cellular and molecular pathomechanisms, and available treatments.
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Affiliation(s)
- Lorenzo Maggi
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
- Correspondence:
| | - Silvia Bonanno
- Neuroimmunology and Neuromuscular Disorders Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20133 Milan, Italy;
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.A.); (J.-F.D.)
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9
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Altamura C, Fonzino A, Tarantino N, Conte E, Liantonio A, Imbrici P, Carratù MR, Pierno S, Desaphy JF. Increased sarcolemma chloride conductance as one of the mechanisms of action of carbonic anhydrase inhibitors in muscle excitability disorders. Exp Neurol 2021; 342:113758. [PMID: 33991525 DOI: 10.1016/j.expneurol.2021.113758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 04/22/2021] [Accepted: 05/10/2021] [Indexed: 01/19/2023]
Abstract
To get insight into the mechanism of action of carbonic anhydrase inhibitors (CAI) in neuromuscular disorders, we investigated effects of dichlorphenamide (DCP) and acetazolamide (ACTZ) on ClC-1 chloride channels and skeletal muscle excitability. We performed patch-clamp experiments to test drugs on chloride currents in HEK293T cells transfected with hClC-1. Using the two-intracellular microelectrode technique in current-clamp mode, we measured the effects of drugs on the resting chloride conductance and action potential properties of sarcolemma in rat and mouse skeletal muscle fibers. Using BCECF dye fluorometry, we measured the effects of ACTZ on intracellular pH in single rat muscle fibers. Similarly to ACTZ, DCP (100 μM) increased hClC-1 chloride currents in HEK cells, because of the negative shift of the open probability voltage dependence and the slowing of deactivation kinetics. Bendroflumethiazide (BFT, 100 μM), structurally related to DCP but lacking activity on carbonic anhydrase, had little effects on chloride currents. In isolated rat muscle fibers, 50-100 μM of ACTZ or DCP, but not BFT, induced a ~ 20% increase of the resting chloride conductance. ACTZ reduced action potential firing in mouse muscle fibers. ACTZ (100 μM) reduced intracellular pH to 6.8 in rat muscle fibers. These results suggest that carbonic anhydrase inhibitors can reduce muscle excitability by increasing ClC-1 channel activity, probably through intracellular acidification. Such a mechanism may contribute in part to the clinical effects of these drugs in myotonia and other muscle excitability disorders.
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Affiliation(s)
- Concetta Altamura
- Section of Pharmacology, Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Adriano Fonzino
- Section of Pharmacology, Dept. of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Nancy Tarantino
- Section of Pharmacology, Dept. of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Elena Conte
- Section of Pharmacology, Dept. of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Antonella Liantonio
- Section of Pharmacology, Dept. of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Section of Pharmacology, Dept. of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Maria Rosaria Carratù
- Section of Pharmacology, Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Sabata Pierno
- Section of Pharmacology, Dept. of Pharmacy & Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Jean-François Desaphy
- Section of Pharmacology, Dept. of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy.
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10
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Camerino GM, Tarantino N, Canfora I, De Bellis M, Musumeci O, Pierno S. Statin-Induced Myopathy: Translational Studies from Preclinical to Clinical Evidence. Int J Mol Sci 2021; 22:ijms22042070. [PMID: 33669797 PMCID: PMC7921957 DOI: 10.3390/ijms22042070] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 02/07/2023] Open
Abstract
Statins are the most prescribed and effective drugs to treat cardiovascular diseases (CVD). Nevertheless, these drugs can be responsible for skeletal muscle toxicity which leads to reduced compliance. The discontinuation of therapy increases the incidence of CVD. Thus, it is essential to assess the risk. In fact, many studies have been performed at preclinical and clinical level to investigate pathophysiological mechanisms and clinical implications of statin myotoxicity. Consequently, new toxicological aspects and new biomarkers have arisen. Indeed, these drugs may affect gene transcription and ion transport and contribute to muscle function impairment. Identifying a marker of toxicity is important to prevent or to cure statin induced myopathy while assuring the right therapy for hypercholesterolemia and counteracting CVD. In this review we focused on the mechanisms of muscle damage discovered in preclinical and clinical studies and highlighted the pathological situations in which statin therapy should be avoided. In this context, preventive or substitutive therapies should also be evaluated.
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Affiliation(s)
- Giulia Maria Camerino
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.M.C.); (N.T.); (I.C.); (M.D.B.)
| | - Nancy Tarantino
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.M.C.); (N.T.); (I.C.); (M.D.B.)
| | - Ileana Canfora
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.M.C.); (N.T.); (I.C.); (M.D.B.)
| | - Michela De Bellis
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.M.C.); (N.T.); (I.C.); (M.D.B.)
| | - Olimpia Musumeci
- Unit of Neurology and Neuromuscular Disorders, Department of Clinical and Experimental Medicine, University of Messina, 98122 Messina, Italy;
| | - Sabata Pierno
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.M.C.); (N.T.); (I.C.); (M.D.B.)
- Correspondence:
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11
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Brenes O, Barbieri R, Vásquez M, Vindas-Smith R, Roig J, Romero A, del Valle G, Bermúdez-Guzmán L, Bertelli S, Pusch M, Morales F. Functional and Structural Characterization of ClC-1 and Na v1.4 Channels Resulting from CLCN1 and SCN4A Mutations Identified Alone and Coexisting in Myotonic Patients. Cells 2021; 10:cells10020374. [PMID: 33670307 PMCID: PMC7918176 DOI: 10.3390/cells10020374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/13/2021] [Accepted: 01/13/2021] [Indexed: 11/25/2022] Open
Abstract
Non-dystrophic myotonias have been linked to loss-of-function mutations in the ClC-1 chloride channel or gain-of-function mutations in the Nav1.4 sodium channel. Here, we describe a family with members diagnosed with Thomsen’s disease. One novel mutation (p.W322*) in CLCN1 and one undescribed mutation (p.R1463H) in SCN4A are segregating in this family. The CLCN1-p.W322* was also found in an unrelated family, in compound heterozygosity with the known CLCN1-p.G355R mutation. One reported mutation, SCN4A-p.T1313M, was found in a third family. Both CLCN1 mutations exhibited loss-of-function: CLCN1-p.W322* probably leads to a non-viable truncated protein; for CLCN1-p.G355R, we predict structural damage, triggering important steric clashes. The SCN4A-p.R1463H produced a positive shift in the steady-state inactivation increasing window currents and a faster recovery from inactivation. These gain-of-function effects are probably due to a disruption of interaction R1463-D1356, which destabilizes the voltage sensor domain (VSD) IV and increases the flexibility of the S4-S5 linker. Finally, modelling suggested that the p.T1313M induces a strong decrease in protein flexibility on the III-IV linker. This study demonstrates that CLCN1-p.W322* and SCN4A-p.R1463H mutations can act alone or in combination as inducers of myotonia. Their co-segregation highlights the necessity for carrying out deep genetic analysis to provide accurate genetic counseling and management of patients.
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Affiliation(s)
- Oscar Brenes
- Departamento de Fisiología, Escuela de Medicina, Universidad de Costa Rica, 11501 San José, Costa Rica;
- Centro de Investigación en Neurociencias (CIN), Universidad de Costa Rica, 11501 San José, Costa Rica
| | | | - Melissa Vásquez
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
| | - Rebeca Vindas-Smith
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
| | - Jeffrey Roig
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
| | - Adarli Romero
- Escuela de Biología, Universidad de Costa Rica, 11501 San José, Costa Rica;
| | - Gerardo del Valle
- Laboratorio de Neurofisiología (Neurolab), 11801 San José, Costa Rica;
| | - Luis Bermúdez-Guzmán
- Sección de Genética y Biotecnología, Escuela de Biología, Universidad de Costa Rica, 11501 San José, Costa Rica;
| | - Sara Bertelli
- Istituto di Biofisica, CNR, 16149 Genova, Italy; (R.B.); (S.B.)
- Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - Michael Pusch
- Istituto di Biofisica, CNR, 16149 Genova, Italy; (R.B.); (S.B.)
- Correspondence: (M.P.); (F.M.); Tel.: +39-0106475-553/522 (M.P.); +506-2511-2124 (F.M.)
| | - Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, 11501 San José, Costa Rica; (M.V.); (R.V.-S.); (J.R.)
- Correspondence: (M.P.); (F.M.); Tel.: +39-0106475-553/522 (M.P.); +506-2511-2124 (F.M.)
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12
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Jehasse K, Jacquerie K, de Froidmont A, Lemoine C, Grisar T, Stouffs K, Lakaye B, Seutin V. Functional analysis of the F337C mutation in the CLCN1 gene associated with dominant myotonia congenita reveals an alteration of the macroscopic conductance and voltage dependence. Mol Genet Genomic Med 2021; 9:e1588. [PMID: 33507632 PMCID: PMC8077071 DOI: 10.1002/mgg3.1588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 11/27/2020] [Accepted: 12/15/2020] [Indexed: 01/14/2023] Open
Abstract
Background Myotonia congenita (MC) is a common channelopathy affecting skeletal muscle and which is due to pathogenic variants within the CLCN1 gene. Various alterations in the function of the channel have been reported and we here illustrate a novel one. Methods A patient presenting the symptoms of myotonia congenita was shown to bear a new heterozygous missense variant in exon 9 of the CLCN1 gene (c.1010 T > G, p.(Phe337Cys)). Confocal imaging and patch clamp recordings of transiently transfected HEK293 cells were used to functionally analyze the effect of this variant on channel properties. Results Confocal imaging showed that the F337C mutant incorporated as well as the WT channel into the plasma membrane. However, in patch clamp, we observed a smaller conductance for F337C at −80 mV. We also found a marked reduction of the fast gating component in the mutant channels, as well as an overall reduced voltage dependence. Conclusion To our knowledge, this is the first report of a mixed alteration in the biophysical properties of hClC‐1 consisting of a reduced conductance at resting potential and an almost abolished voltage dependence.
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Affiliation(s)
- Kevin Jehasse
- Laboratory of NeurophysiologyGIGA InstituteLiegeBelgium
| | - Kathleen Jacquerie
- Department of Electrical Engineering and Computer ScienceLiège UniversityLiègeBelgium
| | | | | | - Thierry Grisar
- Laboratory of Molecular Regulation of NeurogenesisGIGA InstituteLiègeBelgium
| | - Katrien Stouffs
- Neurogenetics Research GroupVrije Universiteit Brussel (VUBUniversitair Ziekenhuis Brussel (UZ Brussel), Reproduction and GeneticsBrusselsBelgium
| | - Bernard Lakaye
- Laboratory of Molecular Regulation of NeurogenesisGIGA InstituteLiègeBelgium
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13
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Desaphy JF, Altamura C, Vicart S, Fontaine B. Targeted Therapies for Skeletal Muscle Ion Channelopathies: Systematic Review and Steps Towards Precision Medicine. J Neuromuscul Dis 2021; 8:357-381. [PMID: 33325393 PMCID: PMC8203248 DOI: 10.3233/jnd-200582] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Skeletal muscle ion channelopathies include non-dystrophic myotonias (NDM), periodic paralyses (PP), congenital myasthenic syndrome, and recently identified congenital myopathies. The treatment of these diseases is mainly symptomatic, aimed at reducing muscle excitability in NDM or modifying triggers of attacks in PP. OBJECTIVE This systematic review collected the evidences regarding effects of pharmacological treatment on muscle ion channelopathies, focusing on the possible link between treatments and genetic background. METHODS We searched databases for randomized clinical trials (RCT) and other human studies reporting pharmacological treatments. Preclinical studies were considered to gain further information regarding mutation-dependent drug effects. All steps were performed by two independent investigators, while two others critically reviewed the entire process. RESULTS For NMD, RCT showed therapeutic benefits of mexiletine and lamotrigine, while other human studies suggest some efficacy of various sodium channel blockers and of the carbonic anhydrase inhibitor (CAI) acetazolamide. Preclinical studies suggest that mutations may alter sensitivity of the channel to sodium channel blockers in vitro, which has been translated to humans in some cases. For hyperkalemic and hypokalemic PP, RCT showed efficacy of the CAI dichlorphenamide in preventing paralysis. However, hypokalemic PP patients carrying sodium channel mutations may have fewer benefits from CAI compared to those carrying calcium channel mutations. Few data are available for treatment of congenital myopathies. CONCLUSIONS These studies provided limited information about the response to treatments of individual mutations or groups of mutations. A major effort is needed to perform human studies for designing a mutation-driven precision medicine in muscle ion channelopathies.
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Affiliation(s)
- Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Concetta Altamura
- Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari Aldo Moro, Bari, Italy
| | - Savine Vicart
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
| | - Bertrand Fontaine
- Sorbonne Université, INSERM, Assistance Publique Hôpitaux de Paris, Centre de Recherche en Myologie-UMR 974, Reference center in neuro-muscular channelopathies, Institute of Myology, Hôpital Universitaire Pitié-Salpêtrière, Paris, France
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14
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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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15
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Modoni A, D'Amico A, Primiano G, Capozzoli F, Desaphy JF, Lo Monaco M. Long-Term Safety and Usefulness of Mexiletine in a Large Cohort of Patients Affected by Non-dystrophic Myotonias. Front Neurol 2020; 11:300. [PMID: 32655465 PMCID: PMC7326038 DOI: 10.3389/fneur.2020.00300] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/30/2020] [Indexed: 02/01/2023] Open
Abstract
Objective: The aim of our study was to evaluate the long-term efficacy and safety of mexiletine in 112 patients affected by genetically confirmed non-dystrophic myotonias. The study was performed at the Neurophysiologic Division of Fondazione Policlinico Universitario A. Gemelli Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), Rome and the Children's Hospital Bambino Gesù, Rome. Methods: The treatment was accepted by 59 patients according to clinical severity, individual needs, and concerns about a chronic medication. Forty-three patients were affected by recessive congenita myotonia, 11 by sodium channel myotonia, and five by dominant congenital myotonia. They underwent clinical examination before and after starting therapy, and Electromyography (EMG). A number of recessive myotonia patients underwent a protocol of repetitive nerve stimulations, for detecting and quantifying the transitory weakness, and a modified version of the Timed Up and Go test, to document and quantify the gait impairment. Results: Treatment duration ranged from 1 month to 20 years and the daily dosages in adults ranged between 200 and 600 mg. No patient developed cardiac arrhythmias causing drug discontinuation. Mexiletine was suspended in 13 cases (22%); in three patients, affected by Sodium Channel myotonia, because flecainide showed better efficacy; in one patient because of a gastric cancer antecedent treatment; in four patients because of untreatable dyspepsia; and five patients considered the treatment not necessary. Conclusions: In our experience, mexiletine is very useful and not expensive. We did not observe any hazarding cardiac arrhythmias. Dyspepsia was the most frequent dose-limiting side effect.
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Affiliation(s)
- Anna Modoni
- Department of Geriatric, Neurologic, Orthopedics and Head-Neck Science, Area of Neuroscience, Institute of Neurology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Adele D'Amico
- Unit of Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Department of Neurosciences, Bambino Gesú Children's Hospital, Rome, Italy
| | - Guido Primiano
- Department of Geriatric, Neurologic, Orthopedics and Head-Neck Science, Area of Neuroscience, Institute of Neurology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | | | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Polyclinic, Bari, Italy
| | - Mauro Lo Monaco
- Department of Geriatric, Neurologic, Orthopedics and Head-Neck Science, Area of Neuroscience, Institute of Neurology, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy.,MiA Onlus ("Miotonici in Associazione"), Portici, Italy
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16
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Conte E, Fonzino A, Cibelli A, De Benedictis V, Imbrici P, Nicchia GP, Pierno S, Camerino GM. Changes in Expression and Cellular Localization of Rat Skeletal Muscle ClC-1 Chloride Channel in Relation to Age, Myofiber Phenotype and PKC Modulation. Front Pharmacol 2020; 11:714. [PMID: 32499703 PMCID: PMC7243361 DOI: 10.3389/fphar.2020.00714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 04/30/2020] [Indexed: 12/16/2022] Open
Abstract
The ClC-1 chloride channel 1 is important for muscle function as it stabilizes resting membrane potential and helps to repolarize the membrane after action potentials. We investigated the contribution of ClC-1 to adaptation of skeletal muscles to needs induced by the different stages of life. We analyzed the ClC-1 gene and protein expression as well as mRNA levels of protein kinase C (PKC) alpha and theta involved in ClC-1 modulation, in soleus (SOL) and extensor digitorum longus (EDL) muscles of rats in all stage of life. The cellular localization of ClC-1 in relation to age was also investigated. Our data show that during muscle development ClC-1 expression differs according to phenotype. In fast-twitch EDL muscles ClC-1 expression increased 10-fold starting at 7 days up to 8 months of life. Conversely, in slow-twitch SOL muscles ClC-1 expression remained constant until 33 days of life and subsequently increased fivefold to reach the adult value. Aging induced a downregulation of gene and protein ClC-1 expression in both muscle types analyzed. The mRNA of PKC-theta revealed the same trend as ClC-1 except in old age, whereas the mRNA of PKC-alpha increased only after 2 months of age. Also, we found that the ClC-1 is localized in both membrane and cytoplasm, in fibers of 12-day-old rats, becoming perfectly localized on the membrane in 2-month-old rats. This study could represent a point of comparison helpful for the identification of accurate pharmacological strategies for all the pathological situations in which ClC-1 protein is altered.
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Affiliation(s)
- Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Adriano Fonzino
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Antonio Cibelli
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Vito De Benedictis
- 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
| | - Grazia Paola Nicchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Sabata Pierno
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Bari, Italy
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17
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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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18
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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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19
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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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20
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Orsini C, Petillo R, D'Ambrosio P, Ergoli M, Picillo E, Scutifero M, Passamano L, De Luca A, Politano L. CLCN1 Molecular Characterization in 19 South-Italian Patients With Dominant and Recessive Type of Myotonia Congenita. Front Neurol 2020; 11:63. [PMID: 32117024 PMCID: PMC7016095 DOI: 10.3389/fneur.2020.00063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/17/2020] [Indexed: 11/13/2022] Open
Abstract
Myotonia congenita is a genetic disease characterized by impaired muscle relaxation after forceful contraction (myotonia). It is caused by mutations in the CLCN1 gene, encoding the voltage-gated chloride channel of skeletal muscle, ClC-1. According to the pattern of inheritance, two distinct clinical forms have been described, Thomsen disease, inherited as an autosomal dominant trait and Becker disease inherited as an autosomal recessive trait. We report genetic and clinical data concerning 19 patients−13 familial and six isolated cases—all but one originating from the Campania Region, in southern Italy. Twelve patients (63.2%) present Becker type myotonia and 7 (36.8%) Thomsen type. Sex ratio M:F in Becker type is 6:6, while in Thomsen myotonia 4:3. The age of onset of the disease ranged from 2 to 15 years in Becker patients, and from 4 to 20 years in Thomsen. Overall 18 mutations were identified, 10 located in the coding part of the gene (exons 1, 3, 4, 5, 7, 8, 13, 15, 21, 22), and four in the intron part (introns 1, 2, 10, 18). All the exon mutations but two were missense mutations. Some of them, such as c.2551 G > A, c.817G > A and c.86A > C recurred more frequently. About 70% of mutations was inherited with an autosomal recessive pattern, two (c.86A and c.817G>A) with both mechanisms. Three novel mutations were identified, never described in the literature: p.Gly276Ser, p.Phe486Ser, and p.Gln812*, associated with Becker phenotype. Furthermore, we identified three CLCN1 mutations—c.86A>C + c.2551G > A, c.313C > T + c.501C > G and 899G > A + c.2284+5C > T, two of them inherited in cis on the same allele, in three unrelated families. The concomitant occurrence of both clinical pictures—Thomsen and Becker—was observed in one family. Intra-familial phenotypic variability was observed in two families, one with Becker phenotype, and one with Thomsen disease. In the latter an incomplete penetrance was hypothesized.
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Affiliation(s)
- Chiara Orsini
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Roberta Petillo
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Paola D'Ambrosio
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Manuela Ergoli
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Esther Picillo
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Marianna Scutifero
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Luigia Passamano
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Alessandro De Luca
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Luisa Politano
- Cardiomiology and Medical Genetics, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
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21
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Morales F, Pusch M. An Up-to-Date Overview of the Complexity of Genotype-Phenotype Relationships in Myotonic Channelopathies. Front Neurol 2020; 10:1404. [PMID: 32010054 PMCID: PMC6978732 DOI: 10.3389/fneur.2019.01404] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022] Open
Abstract
Myotonic disorders are inherited neuromuscular diseases divided into dystrophic myotonias and non-dystrophic myotonias (NDM). The latter is a group of dominant or recessive diseases caused by mutations in genes encoding ion channels that participate in the generation and control of the skeletal muscle action potential. Their altered function causes hyperexcitability of the muscle membrane, thereby triggering myotonia, the main sign in NDM. Mutations in the genes encoding voltage-gated Cl− and Na+ channels (respectively, CLCN1 and SCN4A) produce a wide spectrum of phenotypes, which differ in age of onset, affected muscles, severity of myotonia, degree of hypertrophy, and muscle weakness, disease progression, among others. More than 200 CLCN1 and 65 SCN4A mutations have been identified and described, but just about half of them have been functionally characterized, an approach that is likely extremely helpful to contribute to improving the so-far rather poor clinical correlations present in NDM. The observed poor correlations may be due to: (1) the wide spectrum of symptoms and overlapping phenotypes present in both groups (Cl− and Na+ myotonic channelopathies) and (2) both genes present high genotypic variability. On the one hand, several mutations cause a unique and reproducible phenotype in most patients. On the other hand, some mutations can have different inheritance pattern and clinical phenotypes in different families. Conversely, different mutations can be translated into very similar phenotypes. For these reasons, the genotype-phenotype relationships in myotonic channelopathies are considered complex. Although the molecular bases for the clinical variability present in myotonic channelopathies remain obscure, several hypotheses have been put forward to explain the variability, which include: (a) differential allelic expression; (b) trans-acting genetic modifiers; (c) epigenetic, hormonal, or environmental factors; and (d) dominance with low penetrance. Improvements in clinical tests, the recognition of the different phenotypes that result from particular mutations and the understanding of how a mutation affects the structure and function of the ion channel, together with genetic screening, is expected to improve clinical correlation in NDMs.
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Affiliation(s)
- Fernando Morales
- Instituto de Investigaciones en Salud, Universidad de Costa, San José, Costa Rica
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22
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Camerino GM, Fonzino A, Conte E, De Bellis M, Mele A, Liantonio A, Tricarico D, Tarantino N, Dobrowolny G, Musarò A, Desaphy JF, De Luca A, Pierno S. Elucidating the Contribution of Skeletal Muscle Ion Channels to Amyotrophic Lateral Sclerosis in search of new therapeutic options. Sci Rep 2019; 9:3185. [PMID: 30816241 PMCID: PMC6395744 DOI: 10.1038/s41598-019-39676-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 01/25/2019] [Indexed: 12/11/2022] Open
Abstract
The discovery of pathogenetic mechanisms is essential to identify new therapeutic approaches in Amyotrophic Lateral Sclerosis (ALS). Here we investigated the role of the most important ion channels in skeletal muscle of an ALS animal model (MLC/SOD1G93A) carrying a mutated SOD1 exclusively in this tissue, avoiding motor-neuron involvement. Ion channels are fundamental proteins for muscle function, and also to sustain neuromuscular junction and nerve integrity. By a multivariate statistical analysis, using machine learning algorithms, we identified the discriminant genes in MLC/SOD1G93A mice. Surprisingly, the expression of ClC-1 chloride channel, present only in skeletal muscle, was reduced. Also, the expression of Protein Kinase-C, known to control ClC-1 activity, was increased, causing its inhibition. The functional characterization confirmed the reduction of ClC-1 activity, leading to hyperexcitability and impaired relaxation. The increased expression of ion channel coupled AMPA-receptor may contribute to sustained depolarization and functional impairment. Also, the decreased expression of irisin, a muscle-secreted peptide protecting brain function, may disturb muscle-nerve connection. Interestingly, the in-vitro application of chelerythrine or acetazolamide, restored ClC-1 activity and sarcolemma hyperexcitability in these mice. These findings show that ion channel function impairment in skeletal muscle may lead to motor-neuron increased vulnerability, and opens the possibility to investigate on new compounds as promising therapy.
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Affiliation(s)
- Giulia Maria Camerino
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Adriano Fonzino
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Michela De Bellis
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Antonietta Mele
- 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
| | - Domenico Tricarico
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Nancy Tarantino
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Gabriella Dobrowolny
- DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy.,Center for Life Nano Science at Sapienza, Istituto Italiano di Tecnologia, 00161, Rome, Italy
| | - Antonio Musarò
- DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, 00161 Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy.,Center for Life Nano Science at Sapienza, Istituto Italiano di Tecnologia, 00161, Rome, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Polyclinic, 70124, Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Sabata Pierno
- Department of Pharmacy-Drug Sciences, University of Bari Aldo Moro, 70125, Bari, Italy.
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23
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Becker's myotonia: novel mutations and clinical variability in patients born to consanguineous parents. Acta Neurol Belg 2018; 118:567-572. [PMID: 29480456 DOI: 10.1007/s13760-018-0893-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 02/05/2018] [Indexed: 01/30/2023]
Abstract
Myotonia congenita is an inherited muscle disease present from childhood that is characterized by impaired muscle relaxation after contraction resulting in muscle stiffness; moreover, skeletal striated muscle groups may be involved. Myotonia congenita occurs due to chloride (Cl) channel mutations that reduce the stabilizing Cl conductance, and it is caused by mutations in the CLCN1 gene. This paper describes four patients from two different healthy consanguineous Turkish families with muscle stiffness and easy fatigability. A genetic investigation was performed. Mutation analyses showed a homozygous p.Tyr150* (c.450C > A) mutation in patients 1, 2 and 3 and a homozygous p.Leu159Cysfs*11 (c.475delC) mutation in patient 4 in the CLCN1 gene. These mutations have never been reported before and in silico analyses showed that the mutations were disease causing. They may be predicted to cause nonsense-mediated mRNA decay. Our data expand the spectrum of CLCN1 mutations and provide insights for genotype-phenotype correlations of myotonia congenita.
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24
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Cheng X, Huang Y, Qiu X, Cheng X, Jin Y, Hu Y, Yang B, Zhao J, Lei Y, Zheng F. Novel compound heterozygous mutations in low density lipoprotein receptor gene causes a severe phenotype in a Chinese hypercholesterolemia family. Exp Ther Med 2018; 16:901-907. [PMID: 30112042 DOI: 10.3892/etm.2018.6205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 02/07/2017] [Indexed: 11/05/2022] Open
Abstract
Mutations in the low density lipoprotein receptor (LDLR) gene serve a causative role in the pathophysiology of familial hypercholesterolemia (FH), a common autosomal inherited disorder characterized by abnormal lipid metabolism. The aim of the present study was to investigate genetic defects in a Chinese family with FH. Clinical features and family histories were collected, as were the results of various laboratory tests, including determinations of serum lipid concentrations, ultrasonography and angiography results. Potential mutations in LDLR were screened using direct polymerase chain reaction (PCR) sequencing. Multiple sequence alignments, structure and hydrophobicity predictions were performed in silico. Novel compound heterozygote mutations in LDLR of the proband were identified, with a Trp577Term-bearing maternal allele and a Pro685Leu-bearing paternal allele. The proband, a 27-year-old male, had severe and diffuse coronary stenosis and non-ST segment elevation myocardial infarction, as well as multiple skin xanthomas and high serum lipid levels. The allele-dosage-dependent clinical features, including hypercholesterolemia and peripheral arterial atherosclerosis, were observed in the proband and the other heterozygous patients. Therefore, the coexistence of Pro685Leu and Trp577Term mutations in LDLR is a novel compound heterozygosis in Chinese patients and may lead to a severe FH phenotype. The explanation for the existence of compound heterozygous mutations instead of homozygous mutations in this particular family requires further study.
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Affiliation(s)
- Xinyao Cheng
- Cardiovascular Division, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yifang Huang
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xueping Qiu
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xiaohuan Cheng
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yalei Jin
- Geriatrics Division, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yafei Hu
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Bing Yang
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Jingbo Zhao
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Yuhua Lei
- Ultrasonography Division, Enshi Center Hospital, Enshi, Hubei 445000, P.R. China
| | - Fang Zheng
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
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25
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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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26
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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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27
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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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28
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Maggi L, Ravaglia S, Farinato A, Brugnoni R, Altamura C, Imbrici P, Camerino DC, Padovani A, Mantegazza R, Bernasconi P, Desaphy JF, Filosto M. Coexistence of CLCN1 and SCN4A mutations in one family suffering from myotonia. Neurogenetics 2017; 18:219-225. [PMID: 28993909 DOI: 10.1007/s10048-017-0525-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 10/01/2017] [Indexed: 01/28/2023]
Abstract
Non-dystrophic myotonias are characterized by clinical overlap making it challenging to establish genotype-phenotype correlations. We report clinical and electrophysiological findings in a girl and her father concomitantly harbouring single heterozygous mutations in SCN4A and CLCN1 genes. Functional characterization of N1297S hNav1.4 mutant was performed by patch clamp. The patients displayed a mild phenotype, mostly resembling a sodium channel myotonia. The CLCN1 c.501C>G (p.F167L) mutation has been already described in recessive pedigrees, whereas the SCN4A c.3890A>G (p.N1297S) variation is novel. Patch clamp experiments showed impairment of fast and slow inactivation of the mutated Nav1.4 sodium channel. The present findings suggest that analysis of both SCN4A and CLCN1 genes should be considered in myotonic patients with atypical clinical and neurophysiological features.
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Affiliation(s)
- Lorenzo Maggi
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133, Milan, Italy.
| | | | - Alessandro Farinato
- Department of Pharmacy and Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Raffaella Brugnoni
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133, Milan, Italy
| | - Concetta Altamura
- Department of Pharmacy and Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Paola Imbrici
- Department of Pharmacy and Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Diana Conte Camerino
- Department of Pharmacy and Drug Sciences, University of Bari Aldo Moro, Bari, Italy
| | - Alessandro Padovani
- Center for Neuromuscular Diseases and Neuropathies, Unit of Neurology ASST "Spedali Civili", University of Brescia, Brescia, Italy
| | - Renato Mantegazza
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133, Milan, Italy
| | - Pia Bernasconi
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133, Milan, Italy
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro, Bari, Italy
| | - Massimiliano Filosto
- Center for Neuromuscular Diseases and Neuropathies, Unit of Neurology ASST "Spedali Civili", University of Brescia, Brescia, Italy
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29
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Camerino GM, Musumeci O, Conte E, Musaraj K, Fonzino A, Barca E, Marino M, Rodolico C, Tricarico D, Camerino C, Carratù MR, Desaphy JF, De Luca A, Toscano A, Pierno S. Risk of Myopathy in Patients in Therapy with Statins: Identification of Biological Markers in a Pilot Study. Front Pharmacol 2017; 8:500. [PMID: 28798690 PMCID: PMC5529355 DOI: 10.3389/fphar.2017.00500] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 07/14/2017] [Indexed: 11/24/2022] Open
Abstract
Statin therapy may induce skeletal muscle damage ranging from myalgia to severe rhabdomyolysis. Our previous preclinical studies showed that statin treatment in rats involves the reduction of skeletal muscle ClC-1 chloride channel expression and related chloride conductance (gCl). An increase of the activity of protein kinase C theta (PKC theta) isoform, able to inactivate ClC-1, may contribute to destabilize sarcolemma excitability. These effects can be detrimental for muscle function leading to drug-induced myopathy. Our goal is to study the causes of statin-induced muscle side effects in patients at the aim to identify biological markers useful to prevent and counteract statin-induced muscle damage. We examined 10 patients, who experienced myalgia and hyper-CK-emia after starting statin therapy compared to 9 non-myopathic subjects not using lipid-lowering drugs. Western Blot (WB) analysis showed a 40% reduction of ClC-1 protein and increased expression of phosphorylated PKC in muscle biopsies of statin-treated patients with respect to untreated subjects, independently from their age and statin type. Real-time PCR analysis showed that despite reduction of the protein, the ClC-1 mRNA was not significantly changed, suggesting post-transcriptional modification. The mRNA expression of a series of genes was also evaluated. MuRF-1 was increased in accord with muscle atrophy, MEF-2, calcineurin (CN) and GLUT-4 transporter were reduced, suggesting altered transcription, alteration of glucose homeostasis and energy deficit. Accordingly, the phosphorylated form of AMPK, measured by WB, was increased, suggesting cytoprotective process activation. In parallel, mRNA expression of Notch-1, involved in muscle cell proliferation, was highly expressed in statin-treated patients, indicating active regeneration. Also, PGC-1-alpha and isocitrate-dehydrogenase increased expression together with increased activity of mitochondrial citrate-synthase, measured by spectrophotometric assay, suggests mitochondrial biogenesis. Thus, the reduction of ClC-1 protein and consequent sarcolemma hyperexcitability together with energy deficiency appear to be among the most important alterations to be associated with statin-related risk of myopathy in humans. Thus, it may be important to avoid statin treatment in pathologies characterized by energy deficit and chloride channel malfunction. This study validates the measure of ClC-1 expression as a reliable clinical test for assessing statin-dependent risk of myopathy.
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Affiliation(s)
- Giulia M Camerino
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
| | - Olimpia Musumeci
- Department of Clinical and Experimental Medicine, University of MessinaMessina, Italy
| | - Elena Conte
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
| | - Kejla Musaraj
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
| | - Adriano Fonzino
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
| | - Emanuele Barca
- Department of Clinical and Experimental Medicine, University of MessinaMessina, Italy
| | - Marco Marino
- Department of Clinical and Experimental Medicine, University of MessinaMessina, Italy
| | - Carmelo Rodolico
- Department of Clinical and Experimental Medicine, University of MessinaMessina, Italy
| | - Domenico Tricarico
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
| | - Claudia Camerino
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro Medical SchoolBari, Italy
| | - Maria R Carratù
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro Medical SchoolBari, Italy
| | - Jean-François Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari Aldo Moro Medical SchoolBari, Italy
| | - Annamaria De Luca
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
| | - Antonio Toscano
- Department of Clinical and Experimental Medicine, University of MessinaMessina, Italy
| | - Sabata Pierno
- Section of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo MoroBari, Italy
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30
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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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31
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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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Imbrici P, Liantonio A, Camerino GM, De Bellis M, Camerino C, Mele A, Giustino A, Pierno S, De Luca A, Tricarico D, Desaphy JF, Conte D. Therapeutic Approaches to Genetic Ion Channelopathies and Perspectives in Drug Discovery. Front Pharmacol 2016; 7:121. [PMID: 27242528 PMCID: PMC4861771 DOI: 10.3389/fphar.2016.00121] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 04/25/2016] [Indexed: 12/21/2022] Open
Abstract
In the human genome more than 400 genes encode ion channels, which are transmembrane proteins mediating ion fluxes across membranes. Being expressed in all cell types, they are involved in almost all physiological processes, including sense perception, neurotransmission, muscle contraction, secretion, immune response, cell proliferation, and differentiation. Due to the widespread tissue distribution of ion channels and their physiological functions, mutations in genes encoding ion channel subunits, or their interacting proteins, are responsible for inherited ion channelopathies. These diseases can range from common to very rare disorders and their severity can be mild, disabling, or life-threatening. In spite of this, ion channels are the primary target of only about 5% of the marketed drugs suggesting their potential in drug discovery. The current review summarizes the therapeutic management of the principal ion channelopathies of central and peripheral nervous system, heart, kidney, bone, skeletal muscle and pancreas, resulting from mutations in calcium, sodium, potassium, and chloride ion channels. For most channelopathies the therapy is mainly empirical and symptomatic, often limited by lack of efficacy and tolerability for a significant number of patients. Other channelopathies can exploit ion channel targeted drugs, such as marketed sodium channel blockers. Developing new and more specific therapeutic approaches is therefore required. To this aim, a major advancement in the pharmacotherapy of channelopathies has been the discovery that ion channel mutations lead to change in biophysics that can in turn specifically modify the sensitivity to drugs: this opens the way to a pharmacogenetics strategy, allowing the development of a personalized therapy with increased efficacy and reduced side effects. In addition, the identification of disease modifiers in ion channelopathies appears an alternative strategy to discover novel druggable targets.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Giulia M Camerino
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Michela De Bellis
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Claudia Camerino
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari "Aldo Moro" Bari, Italy
| | - Antonietta Mele
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Arcangela Giustino
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro" Bari, Italy
| | - Sabata Pierno
- 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
| | - Domenico Tricarico
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro" Bari, Italy
| | - Diana Conte
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
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Abstract
Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K(+) levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are "channelopathies" caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1), and several potassium channels (Kir2.1, Kir2.6, and Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics.
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Affiliation(s)
- Stephen C Cannon
- Department of Physiology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
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34
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Vindas-Smith R, Fiore M, Vásquez M, Cuenca P, del Valle G, Lagostena L, Gaitán-Peñas H, Estevez R, Pusch M, Morales F. Identification and Functional Characterization ofCLCN1Mutations Found in Nondystrophic Myotonia Patients. Hum Mutat 2015; 37:74-83. [DOI: 10.1002/humu.22916] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 09/25/2015] [Indexed: 10/22/2022]
Affiliation(s)
- Rebeca Vindas-Smith
- Instituto de Investigaciones en Salud (INISA); Universidad de Costa Rica; San José Costa Rica
| | - Michele Fiore
- Istituto di Biofisica; CNR; Via De Marini 6 Genova Italy
| | - Melissa Vásquez
- Instituto de Investigaciones en Salud (INISA); Universidad de Costa Rica; San José Costa Rica
- Centro de Investigación en Neurociencias (CIN); Universidad de Costa Rica; San José Costa Rica
| | - Patricia Cuenca
- Instituto de Investigaciones en Salud (INISA); Universidad de Costa Rica; San José Costa Rica
- Centro de Investigación en Neurociencias (CIN); Universidad de Costa Rica; San José Costa Rica
- Escuela de Medicina; Universidad de Costa Rica; Curridabat San José Costa Rica
| | - Gerardo del Valle
- Laboratorio de Neurofisiología (Neurolab); Curridabat San José Costa Rica
| | | | - Héctor Gaitán-Peñas
- Departament de Ciències Fisiològiques II; Unitat de Fisiologia; Universitat de Barcelona; Carrer Feixa Llarga s/n, L'Hospitalet de Llobregat Barcelona Spain
- U-750, Centro de Investigación en red de enfermedades raras (CIBERER); ISCIII; Barcelona Spain
| | - Raúl Estevez
- Departament de Ciències Fisiològiques II; Unitat de Fisiologia; Universitat de Barcelona; Carrer Feixa Llarga s/n, L'Hospitalet de Llobregat Barcelona Spain
- U-750, Centro de Investigación en red de enfermedades raras (CIBERER); ISCIII; Barcelona Spain
| | - Michael Pusch
- Istituto di Biofisica; CNR; Via De Marini 6 Genova Italy
| | - Fernando Morales
- Instituto de Investigaciones en Salud (INISA); Universidad de Costa Rica; San José Costa Rica
- Centro de Investigación en Neurociencias (CIN); Universidad de Costa Rica; San José Costa Rica
- Escuela de Medicina; Universidad de Costa Rica; Curridabat San José Costa Rica
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35
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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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36
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Clinical, Molecular, and Functional Characterization of CLCN1 Mutations in Three Families with Recessive Myotonia Congenita. Neuromolecular Med 2015; 17:285-96. [PMID: 26007199 PMCID: PMC4534513 DOI: 10.1007/s12017-015-8356-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 05/07/2015] [Indexed: 01/08/2023]
Abstract
Myotonia congenita (MC) is an inherited muscle disease characterized by impaired muscle relaxation after contraction, resulting in muscle stiffness. Both recessive (Becker’s disease) or dominant (Thomsen’s disease) MC are caused by mutations in the CLCN1 gene encoding the voltage-dependent chloride ClC-1 channel, which is quite exclusively expressed in skeletal muscle. More than 200 CLCN1 mutations have been associated with MC. We provide herein a detailed clinical, molecular, and functional evaluation of four patients with recessive MC belonging to three different families. Four CLCN1 variants were identified, three of which have never been characterized. The c.244A>G (p.T82A) and c.1357C>T (p.R453W) variants were each associated in compound heterozygosity with c.568GG>TC (p.G190S), for which pathogenicity is already known. The new c.809G>T (p.G270V) variant was found in the homozygous state. Patch-clamp studies of ClC-1 mutants expressed in tsA201 cells confirmed the pathogenicity of p.G270V, which greatly shifts the voltage dependence of channel activation toward positive potentials. Conversely, the mechanisms by which p.T82A and p.R453W cause the disease remained elusive, as the mutated channels behave similarly to WT. The results also suggest that p.G190S does not exert dominant-negative effects on other mutated ClC-1 subunits. Moreover, we performed a RT-PCR quantification of selected ion channels transcripts in muscle biopsies of two patients. The results suggest gene expression alteration of sodium and potassium channel subunits in myotonic muscles; if confirmed, such analysis may pave the way toward a better understanding of disease phenotype and a possible identification of new therapeutic options.
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37
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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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Ulzi G, Sansone VA, Magri F, Corti S, Bresolin N, Comi GP, Lucchiari S. In vitro analysis of splice site mutations in the CLCN1 gene using the minigene assay. Mol Biol Rep 2014; 41:2865-74. [PMID: 24452722 DOI: 10.1007/s11033-014-3142-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 01/11/2014] [Indexed: 12/21/2022]
Abstract
Mutations in the chloride channel gene CLCN1 cause the allelic disorders Thomsen (dominant) and Becker (recessive) myotonia congenita (MC). The encoded protein, ClC-1, is the primary channel that mediates chloride (Cl-) conductance in skeletal muscle. Mutations in CLCN1 lower the channel's threshold voltage, leading to spontaneous action potentials that are not coupled to neuromuscular transmission and resulting in myotonia. Over 120 mutations in CLCN1 have been described, 10% of which are splicing defects. Biological specimens suitable for RNA extraction are not always available, but obtaining genomic DNA for analysis is easy and non-invasive. This is the first study to evaluate the pathogenic potential of novel splicing mutations using the minigene approach, which is based on genomic DNA analysis. Splicing mutations accounted for 23% of all pathogenic variants in our cohort of MC patients. Four were heterozygous mutations in four unrelated individuals, belonging to this cohort: c.563G>T in exon 5; c.1169-5T>G in intron 10; c.1251+1G>A in intron 11, and c.1931-2A>G in intron 16. These variants were expressed in HEK 293 cells, and aberrant splicing was verified by in vitro transcription and sequencing of the cDNA. Our findings confirm the need to further investigate the nature of rearrangements associated with this class of mutations and their effects on mature transcripts. In particular, splicing mutations predicted to generate in-frame transcripts may generate out-of-frame mRNA transcripts that do not produce functional ClC-1. Clinically, incomplete molecular evaluation could lead to delayed or faulty diagnosis.
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Affiliation(s)
- Gianna Ulzi
- Neurology Unit, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Via Sforza 35, 20122, Milan, Italy
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Trivedi JR, Cannon SC, Griggs RC. Nondystrophic myotonia: challenges and future directions. Exp Neurol 2013; 253:28-30. [PMID: 24361411 DOI: 10.1016/j.expneurol.2013.12.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/27/2013] [Accepted: 12/10/2013] [Indexed: 12/29/2022]
Abstract
Non-dystrophic myotonias are rare diseases caused by mutations in skeletal muscle chloride and sodium ion channels with considerable phenotypic overlap between diseases. Common symptoms include muscle stiffness, transitory weakness, fatigue, and pain. Although seldom life-shortening, these myotonias cause life-time disability and affected individuals cannot perform many daily activities. A notable feature of the recessive form of chloride channelopathies is the presence of transient weakness. While there has been considerable progress in skeletal muscle channelopathies with regards to identifying biophysical abnormalities, the mechanism of transient weakness remains unclear. A recent study published in Experimental Neurology (Desaphy et al., 2013) explored this question further by comparing the biophysical properties of 3 chloride channel mutations associated with recessive myotonia congenita, with varying susceptibility to transient weakness. The authors identified a variety of functional defects in channel behavior among the 3 mutations, suggesting that this variability contributes to the differing phenotypes among chloride channelopathies. This commentary discusses nondystrophic myotonias, the results of Desaphy et al., and the treatment challenges in this rare disease.
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Affiliation(s)
- Jaya R Trivedi
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Stephen C Cannon
- Department of Neurology and Neurotherapeutics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Robert C Griggs
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
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