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Haug M, Michael M, Ritter P, Kovbasyuk L, Vazakidou ME, Friedrich O. Levosimendan's Effects on Length-Dependent Activation in Murine Fast-Twitch Skeletal Muscle. Int J Mol Sci 2024; 25:6191. [PMID: 38892380 PMCID: PMC11172453 DOI: 10.3390/ijms25116191] [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: 04/22/2024] [Revised: 05/29/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
Levosimendan's calcium sensitizing effects in heart muscle cells are well established; yet, its potential impact on skeletal muscle cells has not been evidently determined. Despite controversial results, levosimendan is still expected to interact with skeletal muscle through off-target sites (further than troponin C). Adding to this debate, we investigated levosimendan's acute impact on fast-twitch skeletal muscle biomechanics in a length-dependent activation study by submersing single muscle fibres in a levosimendan-supplemented solution. We employed our MyoRobot technology to investigate the calcium sensitivity of skinned single muscle fibres alongside their stress-strain response in the presence or absence of levosimendan (100 µM). While control data are in agreement with the theory of length-dependent activation, levosimendan appears to shift the onset of the 'descending limb' of active force generation to longer sarcomere lengths without notably improving myofibrillar calcium sensitivity. Passive stretches in the presence of levosimendan yielded over twice the amount of enlarged restoration stress and Young's modulus in comparison to control single fibres. Both effects have not been described before and may point towards potential off-target sites of levosimendan.
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Affiliation(s)
- Michael Haug
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052 Erlangen, Germany; (M.M.); (P.R.); (L.K.); (M.E.V.); (O.F.)
- Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen, Germany
| | - Mena Michael
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052 Erlangen, Germany; (M.M.); (P.R.); (L.K.); (M.E.V.); (O.F.)
- Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen, Germany
| | - Paul Ritter
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052 Erlangen, Germany; (M.M.); (P.R.); (L.K.); (M.E.V.); (O.F.)
- Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen, Germany
| | - Larisa Kovbasyuk
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052 Erlangen, Germany; (M.M.); (P.R.); (L.K.); (M.E.V.); (O.F.)
| | - Maria Eleni Vazakidou
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052 Erlangen, Germany; (M.M.); (P.R.); (L.K.); (M.E.V.); (O.F.)
| | - Oliver Friedrich
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan Str. 3, 91052 Erlangen, Germany; (M.M.); (P.R.); (L.K.); (M.E.V.); (O.F.)
- Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen, Germany
- School of Biomedical Sciences, University of New South Wales, Wallace Wurth Building, 18 High St., Sydney, NSW 2052, Australia
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Karimi E, Gohlke J, van der Borgh M, Lindqvist J, Hourani Z, Kolb J, Cossette S, Lawlor MW, Ottenheijm C, Granzier H. Characterization of NEB pathogenic variants in patients reveals novel nemaline myopathy disease mechanisms and omecamtiv mecarbil force effects. Acta Neuropathol 2024; 147:72. [PMID: 38634969 PMCID: PMC11026289 DOI: 10.1007/s00401-024-02726-w] [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: 12/22/2023] [Revised: 03/19/2024] [Accepted: 03/26/2024] [Indexed: 04/19/2024]
Abstract
Nebulin, a critical protein of the skeletal muscle thin filament, plays important roles in physiological processes such as regulating thin filament length (TFL), cross-bridge cycling, and myofibril alignment. Pathogenic variants in the nebulin gene (NEB) cause NEB-based nemaline myopathy (NEM2), a genetically heterogeneous disorder characterized by hypotonia and muscle weakness, currently lacking curative therapies. In this study, we examined a cohort of ten NEM2 patients, each with unique pathogenic variants, aiming to understand their impact on mRNA, protein, and functional levels. Results show that pathogenic truncation variants affect NEB mRNA stability and lead to nonsense-mediated decay of the mutated transcript. Moreover, a high incidence of cryptic splice site activation was found in patients with pathogenic splicing variants that are expected to disrupt the actin-binding sites of nebulin. Determination of protein levels revealed patients with either relatively normal or markedly reduced nebulin. We observed a positive relation between the reduction in nebulin and a reduction in TFL, or reduction in tension (both maximal and submaximal tension). Interestingly, our study revealed a pathogenic duplication variant in nebulin that resulted in a four-copy gain in the triplicate region of NEB and a much larger nebulin protein and longer TFL. Additionally, we investigated the effect of Omecamtiv mecarbil (OM), a small-molecule activator of cardiac myosin, on force production of type 1 muscle fibers of NEM2 patients. OM treatment substantially increased submaximal tension across all NEM2 patients ranging from 87 to 318%, with the largest effects in patients with the lowest level of nebulin. In summary, this study indicates that post-transcriptional or post-translational mechanisms regulate nebulin expression. Moreover, we propose that the pathomechanism of NEM2 involves not only shortened but also elongated thin filaments, along with the disruption of actin-binding sites resulting from pathogenic splicing variants. Significantly, our findings highlight the potential of OM treatment to improve skeletal muscle function in NEM2 patients, especially those with large reductions in nebulin levels.
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Affiliation(s)
- Esmat Karimi
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Mila van der Borgh
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
| | - Stacy Cossette
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Michael W Lawlor
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, USA
- Diverge Translational Science Laboratory, Milwaukee, WI, USA
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA
- Department of Physiology, Amsterdam UMC (Location VUMC), Amsterdam, Netherlands
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, USA.
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Claassen WJ, Baelde RJ, Galli RA, de Winter JM, Ottenheijm CAC. Small molecule drugs to improve sarcomere function in those with acquired and inherited myopathies. Am J Physiol Cell Physiol 2023; 325:C60-C68. [PMID: 37212548 PMCID: PMC10281779 DOI: 10.1152/ajpcell.00047.2023] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/23/2023]
Abstract
Muscle weakness is a hallmark of inherited or acquired myopathies. It is a major cause of functional impairment and can advance to life-threatening respiratory insufficiency. During the past decade, several small-molecule drugs that improve the contractility of skeletal muscle fibers have been developed. In this review, we provide an overview of the available literature and the mechanisms of action of small-molecule drugs that modulate the contractility of sarcomeres, the smallest contractile units in striated muscle, by acting on myosin and troponin. We also discuss their use in the treatment of skeletal myopathies. The first of three classes of drugs discussed here increase contractility by decreasing the dissociation rate of calcium from troponin and thereby sensitizing the muscle to calcium. The second two classes of drugs directly act on myosin and stimulate or inhibit the kinetics of myosin-actin interactions, which may be useful in patients with muscle weakness or stiffness.NEW & NOTEWORTHY During the past decade, several small molecule drugs that improve the contractility of skeletal muscle fibers have been developed. In this review, we provide an overview of the available literature and the mechanisms of action of small molecule drugs that modulate the contractility of sarcomeres, the smallest contractile units in striated muscle, by acting on myosin and troponin.
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Affiliation(s)
- Wout J Claassen
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Rianne J Baelde
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Ricardo A Galli
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Josine M de Winter
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
| | - Coen A C Ottenheijm
- Amsterdam UMC Location Vrije Universiteit Amsterdam, Physiology, De Boelelaan, Amsterdam, Netherlands
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Casey JG, Kim ES, Joseph R, Li F, Granzier H, Gupta VA. NRAP reduction rescues sarcomere defects in nebulin-related nemaline myopathy. Hum Mol Genet 2023; 32:1711-1721. [PMID: 36661122 PMCID: PMC10162428 DOI: 10.1093/hmg/ddad011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/18/2022] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
Nemaline myopathy (NM) is a rare neuromuscular disorder associated with congenital or childhood-onset of skeletal muscle weakness and hypotonia, which results in limited motor function. NM is a genetic disorder and mutations in 12 genes are known to contribute to autosomal dominant or recessive forms of the disease. Recessive mutations in nebulin (NEB) are the most common cause of NM affecting about 50% of patients. Because of the large size of the NEB gene and lack of mutational hot spots, developing therapies that can benefit a wide group of patients is challenging. Although there are several promising therapies under investigation, there is no cure for NM. Therefore, targeting disease modifiers that can stabilize or improve skeletal muscle function may represent alternative therapeutic strategies. Our studies have identified Nrap upregulation in nebulin deficiency that contributes to structural and functional deficits in NM. We show that genetic ablation of nrap in nebulin deficiency restored sarcomeric disorganization, reduced protein aggregates and improved skeletal muscle function in zebrafish. Our findings suggest that Nrap is a disease modifier that affects skeletal muscle structure and function in NM; thus, therapeutic targeting of Nrap in nebulin-related NM and related diseases may be beneficial for patients.
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Affiliation(s)
- Jennifer G Casey
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Euri S Kim
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Remi Joseph
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Frank Li
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA
| | - Vandana A Gupta
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
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Gineste C, Laporte J. Therapeutic approaches in different congenital myopathies. Curr Opin Pharmacol 2023; 68:102328. [PMID: 36512981 DOI: 10.1016/j.coph.2022.102328] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/17/2022] [Accepted: 11/12/2022] [Indexed: 12/14/2022]
Abstract
Congenital myopathies are rare and severe genetic diseases affecting the skeletal muscle function in children and adults. They present a variable spectrum of phenotypes and a genetic heterogeneity. Subgroups are defined according to the clinical and histopathological features and encompass core myopathy, centronuclear myopathy, nemaline myopathy and other rare congenital myopathies. No approved treatment exists to date for any congenital myopathies. To tackle this important unmet need, an increased number of proof-of-concept studies recently assessed the therapeutic potential of various strategies, either pharmacological or genetic-based, aiming at counteracting muscle weakness or/and cure the pathology. Here, we list the implicated genes and cellular pathways, and review the therapeutic approaches preclinically tested and the ongoing/completed clinical trials for the different types of congenital myopathies.
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Affiliation(s)
- Charlotte Gineste
- Department of Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, Cnrs UMR7104, Strasbourg University, Illkirch 67404, France
| | - Jocelyn Laporte
- Department of Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, Cnrs UMR7104, Strasbourg University, Illkirch 67404, France.
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Fisher G, Mackels L, Markati T, Sarkozy A, Ochala J, Jungbluth H, Ramdas S, Servais L. Early clinical and pre-clinical therapy development in Nemaline myopathy. Expert Opin Ther Targets 2022; 26:853-867. [PMID: 36524401 DOI: 10.1080/14728222.2022.2157258] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Nemaline myopathies (NM) represent a group of clinically and genetically heterogeneous congenital muscle disorders with the common denominator of nemaline rods on muscle biopsy. NEB and ACTA1 are the most common causative genes. Currently, available treatments are supportive. AREAS COVERED We explored experimental treatments for NM, identifying at least eleven mainly pre-clinical approaches utilizing murine and/or human muscle cells. These approaches target either i) the causative gene or associated genes implicated in the same pathway; ii) pathophysiologically relevant biochemical mechanisms such as calcium/myosin regulation of muscle contraction; iii) myogenesis; iv) other therapies that improve or optimize muscle function more generally; v) and/or combinations of the above. The scope and efficiency of these attempts is diverse, ranging from gene-specific effects to those widely applicable to all NM-associated genes. EXPERT OPINION The wide range of experimental therapies currently under consideration for NM is promising. Potential translation into clinical use requires consideration of additional factors such as the potential muscle type specificity as well as the possibility of gene expression remodeling. Challenges in clinical translation include the rarity and heterogeneity of genotypes, phenotypes, and disease trajectories, as well as the lack of longitudinal natural history data and validated outcomes and biomarkers.
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Affiliation(s)
- Gemma Fisher
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK
| | - Laurane Mackels
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK.,Neuromuscular Reference Center, University and University Hospital of Liège, Liège, Belgium
| | - Theodora Markati
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK
| | - Anna Sarkozy
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Hospital, Institute of Child Health, London, UK
| | - Julien Ochala
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Heinz Jungbluth
- Department of Paediatric Neurology - Neuromuscular Service, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK.,Randall Centre for Cell and Molecular Biophysics, Muscle Signalling Section, Faculty of Life Sciences and Medicine (FoLSM), King's College London, London, UK
| | - Sithara Ramdas
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK.,Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK
| | - Laurent Servais
- MDUK Neuromuscular Centre, Department of Paediatrics, University of Oxford, Oxford, UK.,Neuromuscular Reference Center, University and University Hospital of Liège, Liège, Belgium
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De Novo Missense Mutations in TNNC1 and TNNI3 Causing Severe Infantile Cardiomyopathy Affect Myofilament Structure and Function and Are Modulated by Troponin Targeting Agents. Int J Mol Sci 2021; 22:ijms22179625. [PMID: 34502534 PMCID: PMC8431798 DOI: 10.3390/ijms22179625] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 01/09/2023] Open
Abstract
Rare pediatric non-compaction and restrictive cardiomyopathy are usually associated with a rapid and severe disease progression. While the non-compaction phenotype is characterized by structural defects and is correlated with systolic dysfunction, the restrictive phenotype exhibits diastolic dysfunction. The molecular mechanisms are poorly understood. Target genes encode among others, the cardiac troponin subunits forming the main regulatory protein complex of the thin filament for muscle contraction. Here, we compare the molecular effects of two infantile de novo point mutations in TNNC1 (p.cTnC-G34S) and TNNI3 (p.cTnI-D127Y) leading to severe non-compaction and restrictive phenotypes, respectively. We used skinned cardiomyocytes, skinned fibers, and reconstituted thin filaments to measure the impact of the mutations on contractile function. We investigated the interaction of these troponin variants with actin and their inter-subunit interactions, as well as the structural integrity of reconstituted thin filaments. Both mutations exhibited similar functional and structural impairments, though the patients developed different phenotypes. Furthermore, the protein quality control system was affected, as shown for TnC-G34S using patient's myocardial tissue samples. The two troponin targeting agents levosimendan and green tea extract (-)-epigallocatechin-3-gallate (EGCg) stabilized the structural integrity of reconstituted thin filaments and ameliorated contractile function in vitro in some, but not all, aspects to a similar degree for both mutations.
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de Winter JM, Gineste C, Minardi E, Brocca L, Rossi M, Borsboom T, Beggs AH, Bernard M, Bendahan D, Hwee DT, Malik FI, Pellegrino MA, Bottinelli R, Gondin J, Ottenheijm CAC. Acute and chronic tirasemtiv treatment improves in vivo and in vitro muscle performance in actin-based nemaline myopathy mice. Hum Mol Genet 2021; 30:1305-1320. [PMID: 33909041 PMCID: PMC8255131 DOI: 10.1093/hmg/ddab112] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/09/2021] [Accepted: 04/07/2021] [Indexed: 12/13/2022] Open
Abstract
Nemaline myopathy, a disease of the actin-based thin filament, is one of the most frequent congenital myopathies. To date, no specific therapy is available to treat muscle weakness in nemaline myopathy. We tested the ability of tirasemtiv, a fast skeletal troponin activator that targets the thin filament, to augment muscle force-both in vivo and in vitro-in a nemaline myopathy mouse model with a mutation (H40Y) in Acta1. In Acta1H40Y mice, treatment with tirasemtiv increased the force response of muscles to submaximal stimulation frequencies. This resulted in a reduced energetic cost of force generation, which increases the force production during a fatigue protocol. The inotropic effects of tirasemtiv were present in locomotor muscles and, albeit to a lesser extent, in respiratory muscles, and they persisted during chronic treatment, an important finding as respiratory failure is the main cause of death in patients with congenital myopathy. Finally, translational studies on permeabilized muscle fibers isolated from a biopsy of a patient with the ACTA1H40Y mutation revealed that at physiological Ca2+ concentrations, tirasemtiv increased force generation to values that were close to those generated in muscle fibers of healthy subjects. These findings indicate the therapeutic potential of fast skeletal muscle troponin activators to improve muscle function in nemaline myopathy due to the ACTA1H40Y mutation, and future studies should assess their merit for other forms of nemaline myopathy and for other congenital myopathies.
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Affiliation(s)
- Josine M de Winter
- Department of Physiology, Amsterdam UMC (location VUmc), Amsterdam 1081 HV, The Netherlands
| | | | - Elisa Minardi
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Lorenza Brocca
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Maira Rossi
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
| | - Tamara Borsboom
- Department of Physiology, Amsterdam UMC (location VUmc), Amsterdam 1081 HV, The Netherlands
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Monique Bernard
- Aix-Marseille Univ, CNRS, CRMBM, UMR 7339, 13005 Marseille, France
| | - David Bendahan
- Aix-Marseille Univ, CNRS, CRMBM, UMR 7339, 13005 Marseille, France
| | - Darren T Hwee
- Research and Early Development, Cytokinetics Inc., South San Francisco, CA 94080, USA
| | - Fady I Malik
- Research and Early Development, Cytokinetics Inc., South San Francisco, CA 94080, USA
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
- Interdipartimental Centre for Biology and Sport Medicine, University of Pavia, Pavia 27100, Italy
| | - Roberto Bottinelli
- Department of Molecular Medicine, University of Pavia, Pavia 27100, Italy
- Istituti Clinici Maugeri (IRCCS), Scientific Institute of Pavia, Pavia 27100, Italy
| | - Julien Gondin
- Aix-Marseille Univ, CNRS, CRMBM, UMR 7339, 13005 Marseille, France
- Institut NeuroMyoGène, Université Claude Bernard Lyon 1, CNRS 5310, INSERM U1217, 69008, Lyon, France
| | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam UMC (location VUmc), Amsterdam 1081 HV, The Netherlands
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Multiparametric Mechanistic Profiling of Inotropic Drugs in Adult Human Primary Cardiomyocytes. Sci Rep 2020; 10:7692. [PMID: 32376974 PMCID: PMC7203129 DOI: 10.1038/s41598-020-64657-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 04/10/2020] [Indexed: 01/10/2023] Open
Abstract
Effects of non-cardiac drugs on cardiac contractility can lead to serious adverse events. Furthermore, programs aimed at treating heart failure have had limited success and this therapeutic area remains a major unmet medical need. The challenges in assessing drug effect on cardiac contractility point to the fundamental translational value of the current preclinical models. Therefore, we sought to develop an adult human primary cardiomyocyte contractility model that has the potential to provide a predictive preclinical approach for simultaneously predicting drug-induced inotropic effect (sarcomere shortening) and generating multi-parameter data to profile different mechanisms of action based on cluster analysis of a set of 12 contractility parameters. We report that 17 positive and 9 negative inotropes covering diverse mechanisms of action exerted concentration-dependent increases and decreases in sarcomere shortening, respectively. Interestingly, the multiparametric readout allowed for the differentiation of inotropes operating via distinct mechanisms. Hierarchical clustering of contractility transient parameters, coupled with principal component analysis, enabled the classification of subsets of both positive as well as negative inotropes, in a mechanism-related mode. Thus, human cardiomyocyte contractility model could accurately facilitate informed mechanistic-based decision making, risk management and discovery of molecules with the most desirable pharmacological profile for the correction of heart failure.
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Li F, Kolb J, Crudele J, Tonino P, Hourani Z, Smith JE, Chamberlain JS, Granzier H. Expressing a Z-disk nebulin fragment in nebulin-deficient mouse muscle: effects on muscle structure and function. Skelet Muscle 2020; 10:2. [PMID: 31992366 PMCID: PMC6986074 DOI: 10.1186/s13395-019-0219-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Nebulin is a critical thin filament-binding protein that spans from the Z-disk of the skeletal muscle sarcomere to near the pointed end of the thin filament. Its massive size and actin-binding property allows it to provide the thin filaments with structural and regulatory support. When this protein is lost, nemaline myopathy occurs. Nemaline myopathy causes severe muscle weakness as well as structural defects on a sarcomeric level. There is no known cure for this disease. METHODS We studied whether sarcomeric structure and function can be improved by introducing nebulin's Z-disk region into a nebulin-deficient mouse model (Neb cKO) through adeno-associated viral (AAV) vector therapy. Following this treatment, the structural and functional characteristics of both vehicle-treated and AAV-treated Neb cKO and control muscles were studied. RESULTS Intramuscular injection of this AAV construct resulted in a successful expression of the Z-disk fragment within the target muscles. This expression was significantly higher in Neb cKO mice than control mice. Analysis of protein expression revealed that the nebulin fragment was localized exclusively to the Z-disks and that Neb cKO expressed the nebulin fragment at levels comparable to the level of full-length nebulin in control mice. Additionally, the Z-disk fragment displaced full-length nebulin in control mice, resulting in nemaline rod body formation and a worsening of muscle function. Neb cKO mice experienced a slight functional benefit from the AAV treatment, with a small increase in force and fatigue resistance. Disease progression was also slowed as indicated by improved muscle structure and myosin isoform expression. CONCLUSIONS This study reveals that nebulin fragments are well-received by nebulin-deficient mouse muscles and that limited functional benefits are achievable.
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Affiliation(s)
- Frank Li
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85721, USA
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85721, USA
| | - Julie Crudele
- Department of Neurology, University of Washington, Seattle, WA, 98109-8055, USA
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85721, USA
| | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85721, USA
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85721, USA
| | | | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ, 85721, USA.
- Medical Research Building, RM 325, 1656 E Mabel St, Tucson, AZ, 85721, USA.
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Abstract
Nebulin, encoded by NEB, is a giant skeletal muscle protein of about 6669 amino acids which forms an integral part of the sarcomeric thin filament. In recent years, the nebula around this protein has been largely lifted resulting in the discovery that nebulin is critical for a number of tasks in skeletal muscle. In this review, we firstly discussed nebulin’s role as a structural component of the thin filament and the Z-disk, regulating the length and the mechanical properties of the thin filament as well as providing stability to myofibrils by interacting with structural proteins within the Z-disk. Secondly, we reviewed nebulin’s involvement in the regulation of muscle contraction, cross-bridge cycling kinetics, Ca2+-homeostasis and excitation contraction (EC) coupling. While its role in Ca2+-homeostasis and EC coupling is still poorly understood, a large number of studies have helped to improve our knowledge on how nebulin affects skeletal muscle contractile mechanics. These studies suggest that nebulin affects the number of force generating actin-myosin cross-bridges and may also affect the force that each cross-bridge produces. It may exert this effect by interacting directly with actin and myosin and/or indirectly by potentially changing the localisation and function of the regulatory complex (troponin and tropomyosin). Besides unravelling the biology of nebulin, these studies are particularly helpful in understanding the patho-mechanism of myopathies caused by NEB mutations, providing knowledge which constitutes the critical first step towards the development of therapeutic interventions. Currently, effective treatments are not available, although a number of therapeutic strategies are being investigated.
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12
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Abi-Gerges N, Miller PE, Ghetti A. Human Heart Cardiomyocytes in Drug Discovery and Research: New Opportunities in Translational Sciences. Curr Pharm Biotechnol 2019; 21:787-806. [PMID: 31820682 DOI: 10.2174/1389201021666191210142023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/14/2019] [Accepted: 10/28/2019] [Indexed: 12/28/2022]
Abstract
In preclinical drug development, accurate prediction of drug effects on the human heart is critically important, whether in the context of cardiovascular safety or for the purpose of modulating cardiac function to treat heart disease. Current strategies have significant limitations, whereby, cardiotoxic drugs can escape detection or potential life-saving therapies are abandoned due to false positive toxicity signals. Thus, new and more reliable translational approaches are urgently needed to help accelerate the rate of new therapy development. Renewed efforts in the recovery of human donor hearts for research and in cardiomyocyte isolation methods, are providing new opportunities for preclinical studies in adult primary cardiomyocytes. These cells exhibit the native physiological and pharmacological properties, overcoming the limitations presented by artificial cellular models, animal models and have great potential for providing an excellent tool for preclinical drug testing. Adult human primary cardiomyocytes have already shown utility in assessing drug-induced cardiotoxicity risk and helping in the identification of new treatments for cardiac diseases, such as heart failure and atrial fibrillation. Finally, strategies with actionable decision-making trees that rely on data derived from adult human primary cardiomyocytes will provide the holistic insights necessary to accurately predict human heart effects of drugs.
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Affiliation(s)
- Najah Abi-Gerges
- AnaBios Corporation, 3030 Bunker Hill St., Suite 312, San Diego, CA 92109, United States
| | - Paul E Miller
- AnaBios Corporation, 3030 Bunker Hill St., Suite 312, San Diego, CA 92109, United States
| | - Andre Ghetti
- AnaBios Corporation, 3030 Bunker Hill St., Suite 312, San Diego, CA 92109, United States
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13
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Abstract
Nemaline myopathy (NM) is among the most common non-dystrophic congenital myopathies (incidence 1:50.000). Hallmark features of NM are skeletal muscle weakness and the presence of nemaline bodies in the muscle fiber. The clinical phenotype of NM patients is quite diverse, ranging from neonatal death to normal lifespan with almost normal motor function. As the respiratory muscles are involved as well, severely affected patients are ventilator-dependent. The mechanisms underlying muscle weakness in NM are currently poorly understood. Therefore, no therapeutic treatment is available yet. Eleven implicated genes have been identified: ten genes encode proteins that are either components of thin filament, or are thought to contribute to stability or turnover of thin filament proteins. The thin filament is a major constituent of the sarcomere, the smallest contractile unit in muscle. It is at this level of contraction – thin-thick filament interaction – where muscle weakness originates in NM patients. This review focusses on how sarcomeric gene mutations directly compromise sarcomere function in NM. Insight into the contribution of sarcomeric dysfunction to muscle weakness in NM, across the genes involved, will direct towards the development of targeted therapeutic strategies.
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Affiliation(s)
| | - Coen A.C. Ottenheijm
- Correspondence to: Coen Ottenheijm, PhD, Department of Physiology, VU University Medical Center, O|2 building, 12W-51, De Boelelaan 1118, 1081 HV Amsterdam, The Netherlands. Tel.: +31 20 4448123; Fax: +31 20 4448124; E-mail:
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14
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Abstract
The congenital myopathies are a genetically heterogeneous and diverse group of early-onset, nondystrophic neuromuscular disorders. While the originally reported "classical" entities within this group - Central Core Disease, Multiminicore Disease, Nemaline Myopathy, and Centronuclear Myopathy - were defined by the predominant finding on muscle biopsy, "novel" forms with multiple, subtle, and unusual histopathologic features have been described more recently, reflective of an expanding phenotypical spectrum. The main disease mechanisms concern excitation-contraction coupling, intracellular calcium homeostasis, and thin/thick filament interactions. Management to date has been mainly supportive. Therapeutic strategies currently at various stages of exploration include genetic interventions aimed at direct correction of the underlying genetic defect, enzyme replacement therapy, and pharmacologic approaches, either specifically targeting the principal effect of the underlying gene mutation, or addressing its downstream consequences more generally. Clinical trial development is accelerating but will require more robust natural history data and tailored outcome measures.
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Affiliation(s)
- Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina's Children Hospital, Guy's and St. Thomas' Hospital NHS Foundation Trust, London, United Kingdom; Randall Division for Cell and Molecular Biophysics, Muscle Signalling Section, London, United Kingdom; Department of Basic and Clinical Neuroscience, IoPPN, King's College, London, United Kingdom.
| | - Francesco Muntoni
- The Dubowitz Neuromuscular Centre, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health & Great Ormond Street Hospital for Children, London, United Kingdom; NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
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15
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Joureau B, de Winter JM, Conijn S, Bogaards SJP, Kovacevic I, Kalganov A, Persson M, Lindqvist J, Stienen GJM, Irving TC, Ma W, Yuen M, Clarke NF, Rassier DE, Malfatti E, Romero NB, Beggs AH, Ottenheijm CAC. Dysfunctional sarcomere contractility contributes to muscle weakness in ACTA1-related nemaline myopathy (NEM3). Ann Neurol 2018; 83:269-282. [PMID: 29328520 DOI: 10.1002/ana.25144] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Nemaline myopathy (NM) is one of the most common congenital nondystrophic myopathies and is characterized by muscle weakness, often from birth. Mutations in ACTA1 are a frequent cause of NM (ie, NEM3). ACTA1 encodes alpha-actin 1, the main constituent of the sarcomeric thin filament. The mechanisms by which mutations in ACTA1 contribute to muscle weakness in NEM3 are incompletely understood. We hypothesized that sarcomeric dysfunction contributes to muscle weakness in NEM3 patients. METHODS To test this hypothesis, we performed contractility measurements in individual muscle fibers and myofibrils obtained from muscle biopsies of 14 NEM3 patients with different ACTA1 mutations. To identify the structural basis for impaired contractility, low angle X-ray diffraction and stimulated emission-depletion microscopy were applied. RESULTS Our findings reveal that muscle fibers of NEM3 patients display a reduced maximal force-generating capacity, which is caused by dysfunctional sarcomere contractility in the majority of patients, as revealed by contractility measurements in myofibrils. Low angle X-ray diffraction and stimulated emission-depletion microscopy indicate that dysfunctional sarcomere contractility in NEM3 patients involves a lower number of myosin heads binding to actin during muscle activation. This lower number is not the result of reduced thin filament length. Interestingly, the calcium sensitivity of force is unaffected in some patients, but decreased in others. INTERPRETATION Dysfunctional sarcomere contractility is an important contributor to muscle weakness in the majority of NEM3 patients. This information is crucial for patient stratification in future clinical trials. Ann Neurol 2018;83:269-282.
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Affiliation(s)
- Barbara Joureau
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | | | - Stefan Conijn
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Sylvia J P Bogaards
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Igor Kovacevic
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Albert Kalganov
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Malin Persson
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada.,Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - Johan Lindqvist
- Department of Molecular and Cellular Biology and Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
| | - Ger J M Stienen
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Thomas C Irving
- Biophysics Collaborative Access Team, Center for Synchrotron Radiation Research and Instrumentation, and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | - Weikang Ma
- Biophysics Collaborative Access Team, Center for Synchrotron Radiation Research and Instrumentation, and Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | - Michaela Yuen
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.,Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Pediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Pediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia
| | - Dilson E Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Edoardo Malfatti
- Pierre and Marie Curie University/University of Paris VI, Sorbonne Universities, National Institute of Health and Medical Research UMRS974, National Center for Scientific Research FRE3617, Center for Research in Myology, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Norma B Romero
- Pierre and Marie Curie University/University of Paris VI, Sorbonne Universities, National Institute of Health and Medical Research UMRS974, National Center for Scientific Research FRE3617, Center for Research in Myology, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Alan H Beggs
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Coen A C Ottenheijm
- Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.,Department of Molecular and Cellular Biology and Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ
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16
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Congenital myopathies: disorders of excitation-contraction coupling and muscle contraction. Nat Rev Neurol 2018; 14:151-167. [PMID: 29391587 DOI: 10.1038/nrneurol.2017.191] [Citation(s) in RCA: 178] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The congenital myopathies are a group of early-onset, non-dystrophic neuromuscular conditions with characteristic muscle biopsy findings, variable severity and a stable or slowly progressive course. Pronounced weakness in axial and proximal muscle groups is a common feature, and involvement of extraocular, cardiorespiratory and/or distal muscles can implicate specific genetic defects. Central core disease (CCD), multi-minicore disease (MmD), centronuclear myopathy (CNM) and nemaline myopathy were among the first congenital myopathies to be reported, and they still represent the main diagnostic categories. However, these entities seem to belong to a much wider phenotypic spectrum. To date, congenital myopathies have been attributed to mutations in over 20 genes, which encode proteins implicated in skeletal muscle Ca2+ homeostasis, excitation-contraction coupling, thin-thick filament assembly and interactions, and other mechanisms. RYR1 mutations are the most frequent genetic cause, and CCD and MmD are the most common subgroups. Next-generation sequencing has vastly improved mutation detection and has enabled the identification of novel genetic backgrounds. At present, management of congenital myopathies is largely supportive, although new therapeutic approaches are reaching the clinical trial stage.
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17
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18
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Muscle weakness in respiratory and peripheral skeletal muscles in a mouse model for nebulin-based nemaline myopathy. Neuromuscul Disord 2016; 27:83-89. [PMID: 27890461 DOI: 10.1016/j.nmd.2016.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 09/21/2016] [Accepted: 10/11/2016] [Indexed: 12/28/2022]
Abstract
Nemaline myopathy is among the most common non-dystrophic congenital myopathies, and is characterized by the presence of nemaline rods in skeletal muscles fibers, general muscle weakness, and hypotonia. Although respiratory failure is the main cause of death in nemaline myopathy, only little is known regarding the contractile strength of the diaphragm, the main muscle of inspiration. To investigate diaphragm contractility, in the present study we took advantage of a mouse model for nebulin-based nemaline myopathy that we recently developed. In this mouse model, exon 55 of Neb is deleted (NebΔExon55), a mutation frequently found in patients. Diaphragm contractility was determined in permeabilized muscle fibers and was compared to the contractility of permeabilized fibers from three peripheral skeletal muscles: soleus, extensor digitorum longus, and gastrocnemius. The force generating capacity of diaphragm muscle fibers of NebΔExon55 mice was reduced to 25% of wildtype levels, indicating severe contractile weakness. The contractile weakness of diaphragm fibers was more pronounced than that observed in soleus muscle, but not more pronounced than that observed in extensor digitorum longus and gastrocnemius muscles. The reduced muscle contractility was at least partly caused by changes in cross-bridge cycling kinetics which reduced the number of bound cross-bridges. The severe diaphragm weakness likely contributes to the development of respiratory failure in NebΔExon55 mice and might explain their early, postnatal death.
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19
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Jungbluth H, Ochala J, Treves S, Gautel M. Current and future therapeutic approaches to the congenital myopathies. Semin Cell Dev Biol 2016; 64:191-200. [PMID: 27515125 DOI: 10.1016/j.semcdb.2016.08.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 08/04/2016] [Accepted: 08/08/2016] [Indexed: 12/14/2022]
Abstract
The congenital myopathies - including Central Core Disease (CCD), Multi-minicore Disease (MmD), Centronuclear Myopathy (CNM), Nemaline Myopathy (NM) and Congenital Fibre Type Disproportion (CFTD) - are a genetically heterogeneous group of early-onset neuromuscular conditions characterized by distinct histopathological features, and associated with a substantial individual and societal disease burden. Appropriate supportive management has substantially improved patient morbidity and mortality but there is currently no cure. Recent years have seen an exponential increase in the genetic and molecular understanding of these conditions, leading to the identification of underlying defects in proteins involved in calcium homeostasis and excitation-contraction coupling, thick/thin filament assembly and function, redox regulation, membrane trafficking and/or autophagic pathways. Based on these findings, specific therapies are currently being developed, or are already approaching the clinical trial stage. Despite undeniable progress, therapy development faces considerable challenges, considering the rarity and diversity of specific conditions, and the size and complexity of some of the genes and proteins involved. The present review will summarize the key genetic, histopathological and clinical features of specific congenital myopathies, and outline therapies already available or currently being developed in the context of known pathogenic mechanisms. The relevance of newly discovered molecular mechanisms and novel gene editing strategies for future therapy development will be discussed.
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Affiliation(s)
- Heinz Jungbluth
- Department of Paediatric Neurology, Neuromuscular Service, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, United Kingdom; Randall Division for Cell and Molecular Biophysics, Muscle Signalling Section Biophysics and Cardiovascular Division, King's College BHF Centre of Research Excellence, United Kingdom; Department of Basic and Clinical Neuroscience, IoPPN, King's College, London, United Kingdom.
| | - Julien Ochala
- Centre of Human and Aerospace Physiological Sciences, King's College London, United Kingdom
| | - Susan Treves
- Departments of Biomedicine and Anaesthesia, Basel University Hospital, 4031 Basel, Switzerland
| | - Mathias Gautel
- Randall Division for Cell and Molecular Biophysics, Muscle Signalling Section Biophysics and Cardiovascular Division, King's College BHF Centre of Research Excellence, United Kingdom
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20
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Winter JMD, Joureau B, Lee EJ, Kiss B, Yuen M, Gupta VA, Pappas CT, Gregorio CC, Stienen GJM, Edvardson S, Wallgren-Pettersson C, Lehtokari VL, Pelin K, Malfatti E, Romero NB, Engelen BGV, Voermans NC, Donkervoort S, Bönnemann CG, Clarke NF, Beggs AH, Granzier H, Ottenheijm CAC. Mutation-specific effects on thin filament length in thin filament myopathy. Ann Neurol 2016; 79:959-69. [PMID: 27074222 DOI: 10.1002/ana.24654] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 03/22/2016] [Accepted: 03/27/2016] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Thin filament myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin filament. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin filament, an important determinant of force generation. METHODS We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin filaments, in muscle fibers from 51 patients with thin filament myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. RESULTS Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force-sarcomere length relations, indicative of shorter thin filaments. Confocal microscopy confirmed shorter thin filaments in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin filament myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin filaments was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin-thick filament overlap. INTERPRETATION These findings might provide a novel direction for the development of therapeutic strategies for thin filament myopathy patients with shortened thin filament lengths. Ann Neurol 2016;79:959-969.
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Affiliation(s)
- Josine M de Winter
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Barbara Joureau
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands
| | - Eun-Jeong Lee
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Balázs Kiss
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Michaela Yuen
- Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia
| | - Vandana A Gupta
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Christopher T Pappas
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Ger J M Stienen
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands.,Department of Physics and Astronomy, VU University, Amsterdam, the Netherlands
| | - Simon Edvardson
- Pediatric Neurology Unit, Hadassah University Hospital, Jerusalem, Israel
| | - Carina Wallgren-Pettersson
- Department of Medical and Clinical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.,Folkhaelsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland
| | - Vilma-Lotta Lehtokari
- Department of Medical and Clinical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.,Folkhaelsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland
| | - Katarina Pelin
- Folkhaelsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland.,Division of Genetics, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Edoardo Malfatti
- Center for Research in Myology, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Norma B Romero
- Center for Research in Myology, Pitié-Salpêtrière Hospital Group, Paris, France
| | - Baziel G van Engelen
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Nicol C Voermans
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Sandra Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institutes of Health, Bethesda, MD
| | - C G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institutes of Health, Bethesda, MD
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, Children's Hospital at Westmead, Westmead, New South Wales, Australia.,Discipline of Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia
| | - Alan H Beggs
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Coen A C Ottenheijm
- Department of Physiology, VU University Medical Center, Amsterdam, the Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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21
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Abstract
Efficient muscle contraction in skeletal muscle is predicated on the regulation of actin filament lengths. In one long-standing model that was prominent for decades, the giant protein nebulin was proposed to function as a 'molecular ruler' to specify the lengths of the thin filaments. This theory was questioned by many observations, including experiments in which the length of nebulin was manipulated in skeletal myocytes; this approach revealed that nebulin functions to stabilize filamentous actin, allowing thin filaments to reach mature lengths. In addition, more recent data, mostly from in vivo models and identification of new interacting partners, have provided evidence that nebulin is not merely a structural protein. Nebulin plays a role in numerous cellular processes including regulation of muscle contraction, Z-disc formation, and myofibril organization and assembly.
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Affiliation(s)
- Miensheng Chu
- Department of Cellular and Molecular Medicine and the Sarver Molecular Cardiovascular Research Program, The University of Arizona, 1656 East Mabel, MRB315, Tucson, AZ 85724, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine and the Sarver Molecular Cardiovascular Research Program, The University of Arizona, 1656 East Mabel, MRB315, Tucson, AZ 85724, USA
| | - Christopher T Pappas
- Department of Cellular and Molecular Medicine and the Sarver Molecular Cardiovascular Research Program, The University of Arizona, 1656 East Mabel, MRB315, Tucson, AZ 85724, USA
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22
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Yuen M, Cooper ST, Marston SB, Nowak KJ, McNamara E, Mokbel N, Ilkovski B, Ravenscroft G, Rendu J, de Winter JM, Klinge L, Beggs AH, North KN, Ottenheijm CAC, Clarke NF. Muscle weakness in TPM3-myopathy is due to reduced Ca2+-sensitivity and impaired acto-myosin cross-bridge cycling in slow fibres. Hum Mol Genet 2015; 24:6278-92. [PMID: 26307083 DOI: 10.1093/hmg/ddv334] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/10/2015] [Indexed: 11/13/2022] Open
Abstract
Dominant mutations in TPM3, encoding α-tropomyosinslow, cause a congenital myopathy characterized by generalized muscle weakness. Here, we used a multidisciplinary approach to investigate the mechanism of muscle dysfunction in 12 TPM3-myopathy patients. We confirm that slow myofibre hypotrophy is a diagnostic hallmark of TPM3-myopathy, and is commonly accompanied by skewing of fibre-type ratios (either slow or fast fibre predominance). Patient muscle contained normal ratios of the three tropomyosin isoforms and normal fibre-type expression of myosins and troponins. Using 2D-PAGE, we demonstrate that mutant α-tropomyosinslow was expressed, suggesting muscle dysfunction is due to a dominant-negative effect of mutant protein on muscle contraction. Molecular modelling suggested mutant α-tropomyosinslow likely impacts actin-tropomyosin interactions and, indeed, co-sedimentation assays showed reduced binding of mutant α-tropomyosinslow (R168C) to filamentous actin. Single fibre contractility studies of patient myofibres revealed marked slow myofibre specific abnormalities. At saturating [Ca(2+)] (pCa 4.5), patient slow fibres produced only 63% of the contractile force produced in control slow fibres and had reduced acto-myosin cross-bridge cycling kinetics. Importantly, due to reduced Ca(2+)-sensitivity, at sub-saturating [Ca(2+)] (pCa 6, levels typically released during in vivo contraction) patient slow fibres produced only 26% of the force generated by control slow fibres. Thus, weakness in TPM3-myopathy patients can be directly attributed to reduced slow fibre force at physiological [Ca(2+)], and impaired acto-myosin cross-bridge cycling kinetics. Fast myofibres are spared; however, they appear to be unable to compensate for slow fibre dysfunction. Abnormal Ca(2+)-sensitivity in TPM3-myopathy patients suggests Ca(2+)-sensitizing drugs may represent a useful treatment for this condition.
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Affiliation(s)
- Michaela Yuen
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia,
| | - Sandra T Cooper
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Steve B Marston
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Kristen J Nowak
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Elyshia McNamara
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Nancy Mokbel
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Faculty of Health Sciences, St. George Health Complex, The University of Balamand, Beirut, Lebanon
| | - Biljana Ilkovski
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research and the Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - John Rendu
- Département de Biochimie Toxicologie et Pharmacologie, Département de Biochimie Génétique et Moléculaire, Centre Hospitalier Universitaire de Grenoble, Grenoble, France
| | - Josine M de Winter
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Lars Klinge
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neurology, Faculty of Medicine, Georg August University, Göttingen, Germany
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kathryn N North
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia, Murdoch Children's Research Institute, the Royal Children's Hospital, Parkville, Australia and Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Coen A C Ottenheijm
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Nigel F Clarke
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Westmead, Australia, Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
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