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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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2
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Karimi E, van der Borgh M, Lindqvist J, Gohlke J, Hourani Z, Kolb J, Cossette S, Lawlor MW, Ottenheijm C, Granzier H. Characterization of NEB mutations in patients reveals novel nemaline myopathy disease mechanisms and omecamtiv mecarbil force effects. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572678. [PMID: 38187705 PMCID: PMC10769406 DOI: 10.1101/2023.12.20.572678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
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. Mutations in the nebulin gene ( NEB ) cause NEB-based nemaline myopathy (NEM2), a genetically heterogeneous disorder characterized by hypotonia and muscle weakness, currently lacking therapies targeting the underlying pathological mechanisms. In this study, we examined a cohort of ten NEM2 patients, each with unique mutations, aiming to understand their impact on mRNA, protein, and functional levels. Results show that truncation mutations 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 splicing mutations which is expected to disrupt the actin-binding sites of nebulin. Determination of protein levels revealed patients with relatively normal nebulin levels and others with markedly reduced nebulin. We observed a positive relation between the reduction in nebulin and a reduction in TFL, and a positive relation between the reduction in nebulin level and the reduction in tension (both maximal and submaximal tension). Interestingly, our study revealed a duplication mutation in nebulin that resulted in a 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 I muscle fibers of NEM2 patients. OM treatment substantially increased submaximal tension across all NEM2 patients ranging from 87-318%, 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 splicing mutations. 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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3
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Lindqvist J, Granzier H. Pharmacological Inhibition of Myostatin in a Mouse Model of Typical Nemaline Myopathy Increases Muscle Size and Force. Int J Mol Sci 2023; 24:15124. [PMID: 37894805 PMCID: PMC10606666 DOI: 10.3390/ijms242015124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/27/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023] Open
Abstract
Nemaline myopathy is one of the most common non-dystrophic congenital myopathies. Individuals affected by this condition experience muscle weakness and muscle smallness, often requiring supportive measures like wheelchairs or respiratory support. A significant proportion of patients, approximately one-third, exhibit compound heterozygous nebulin mutations, which usually give rise to the typical form of the disease. Currently, there are no approved treatments available for nemaline myopathy. Our research explored the modulation of myostatin, a negative regulator of muscle mass, in combating the muscle smallness associated with the disease. To investigate the effect of myostatin inhibition, we employed a mouse model with compound heterozygous nebulin mutations that mimic the typical form of the disease. The mice were treated with mRK35, a myostatin antibody, through weekly intraperitoneal injections of 10 mg/kg mRK35, commencing at two weeks of age and continuing until the mice reached four months of age. The treatment resulted in an increase in body weight and an approximate 20% muscle weight gain across most skeletal muscles, without affecting the heart. The minimum Feret diameter of type IIA and IIB fibers exhibited an increase in compound heterozygous mice, while only type IIB fibers demonstrated an increase in wild-type mice. In vitro mechanical experiments conducted on intact extensor digitorum longus muscle revealed that mRK35 augmented the physiological cross-sectional area of muscle fibers and enhanced absolute tetanic force in both wild-type and compound heterozygous mice. Furthermore, mRK35 administration improved grip strength in treated mice. Collectively, these findings indicate that inhibiting myostatin can mitigate the muscle deficits in nebulin-based typical nemaline myopathy, potentially serving as a much-needed therapeutic option.
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Affiliation(s)
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, USA;
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4
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Tinklenberg JA, Slick RA, Sutton J, Zhang L, Meng H, Beatka MJ, Vanden Avond M, Prom MJ, Ott E, Montanaro F, Heisner J, Toro R, Hardeman EC, Geurts AM, Stowe DF, Hill RB, Lawlor MW. Different Mouse Models of Nemaline Myopathy Harboring Acta1 Mutations Display Differing Abnormalities Related to Mitochondrial Biology. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1548-1567. [PMID: 37419385 PMCID: PMC10548277 DOI: 10.1016/j.ajpath.2023.06.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 06/20/2023] [Accepted: 06/23/2023] [Indexed: 07/09/2023]
Abstract
ACTA1 encodes skeletal muscle-specific α-actin, which polymerizes to form the thin filament of the sarcomere. Mutations in ACTA1 are responsible for approximately 30% of nemaline myopathy (NM) cases. Previous studies of weakness in NM have focused on muscle structure and contractility, but genetic issues alone do not explain the phenotypic heterogeneity observed in patients with NM or NM mouse models. To identify additional biological processes related to NM phenotypic severity, proteomic analysis was performed using muscle protein isolates from wild-type mice in comparison to moderately affected knock-in (KI) Acta1H40Y and the minimally affected transgenic (Tg) ACTA1D286G NM mice. This analysis revealed abnormalities in mitochondrial function and stress-related pathways in both mouse models, supporting an in-depth assessment of mitochondrial biology. Interestingly, evaluating each model in comparison to its wild-type counterpart identified different degrees of mitochondrial abnormality that correlated well with the phenotypic severity of the mouse model. Muscle histology, mitochondrial respiration, electron transport chain function, and mitochondrial transmembrane potential were all normal or minimally affected in the TgACTA1D286G mouse model. In contrast, the more severely affected KI.Acta1H40Y mice displayed significant abnormalities in relation to muscle histology, mitochondrial respirometry, ATP, ADP, and phosphate content, and mitochondrial transmembrane potential. These findings suggest that abnormal energy metabolism is related to symptomatic severity in NM and may constitute a contributor to phenotypic variability and a novel treatment target.
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Affiliation(s)
- Jennifer A Tinklenberg
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Clinical and Translational Science Institute, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Rebecca A Slick
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Clinical and Translational Science Institute, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jessica Sutton
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Liwen Zhang
- Mass Spectrometry and Proteomics Facility, Campus Chemical Instrument Center, The Ohio State University, Columbus, Ohio
| | - Hui Meng
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Margaret J Beatka
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mark Vanden Avond
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mariah J Prom
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Emily Ott
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Federica Montanaro
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neuroscience Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, United Kingdom; NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - James Heisner
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Rafael Toro
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Edna C Hardeman
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Mellowes Center for Genomic Sciences and Precision Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - David F Stowe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Michael W Lawlor
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin.
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Slick RA, Tinklenberg JA, Sutton J, Zhang L, Meng H, Beatka MJ, Vanden Avond M, Prom MJ, Ott E, Montanaro F, Heisner J, Toro R, Granzier H, Geurts AM, Stowe DF, Hill RB, Lawlor MW. Aberrations in Energetic Metabolism and Stress-Related Pathways Contribute to Pathophysiology in the Neb Conditional Knockout Mouse Model of Nemaline Myopathy. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1528-1547. [PMID: 37422147 PMCID: PMC10548278 DOI: 10.1016/j.ajpath.2023.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 05/08/2023] [Accepted: 06/08/2023] [Indexed: 07/10/2023]
Abstract
Nemaline myopathy (NM) is a genetically and clinically heterogeneous disease that is diagnosed on the basis of the presence of nemaline rods on skeletal muscle biopsy. Although NM has typically been classified by causative genes, disease severity or prognosis cannot be predicted. The common pathologic end point of nemaline rods (despite diverse genetic causes) and an unexplained range of muscle weakness suggest that shared secondary processes contribute to the pathogenesis of NM. We speculated that these processes could be identified through a proteome-wide interrogation using a mouse model of severe NM in combination with pathway validation and structural/functional analyses. A proteomic analysis was performed using skeletal muscle tissue from the Neb conditional knockout mouse model compared with its wild-type counterpart to identify pathophysiologically relevant biological processes that might impact disease severity or provide new treatment targets. A differential expression analysis and Ingenuity Pathway Core Analysis predicted perturbations in several cellular processes, including mitochondrial dysfunction and changes in energetic metabolism and stress-related pathways. Subsequent structural and functional studies demonstrated abnormal mitochondrial distribution, decreased mitochondrial respiratory function, an increase in mitochondrial transmembrane potential, and extremely low ATP content in Neb conditional knockout muscles relative to wild type. Overall, the findings of these studies support a role for severe mitochondrial dysfunction as a novel contributor to muscle weakness in NM.
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Affiliation(s)
- Rebecca A Slick
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Clinical and Translational Science Institute, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jennifer A Tinklenberg
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Clinical and Translational Science Institute, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jessica Sutton
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Liwen Zhang
- Mass Spectrometry and Proteomics Facility, Campus Chemical Instrument Center, The Ohio State University, Columbus, Ohio
| | - Hui Meng
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Margaret J Beatka
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mark Vanden Avond
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mariah J Prom
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Emily Ott
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Federica Montanaro
- Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neuroscience Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, United Kingdom the NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom; NIHR Great Ormond Street Hospital Biomedical Research Centre, London, United Kingdom
| | - James Heisner
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Rafael Toro
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Henk Granzier
- College of Medicine, University of Arizona, Tucson, Arizona
| | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Mellowes Center for Genomic Sciences and Precision Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - David F Stowe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Joint Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, Wisconsin
| | - R Blake Hill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Michael W Lawlor
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin.
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6
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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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Hamm SE, Fathalikhani DD, Bukovec KE, Addington AK, Zhang H, Perry JB, McMillan RP, Lawlor MW, Prom MJ, Vanden Avond MA, Kumar SN, Coleman KE, Dupont JB, Mack DL, Brown DA, Morris CA, Gonzalez JP, Grange RW. Voluntary wheel running complements microdystrophin gene therapy to improve muscle function in mdx mice. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 21:144-160. [PMID: 33850950 PMCID: PMC8020351 DOI: 10.1016/j.omtm.2021.02.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 02/25/2021] [Indexed: 12/12/2022]
Abstract
We tested the hypothesis that voluntary wheel running would complement microdystrophin gene therapy to improve muscle function in young mdx mice, a model of Duchenne muscular dystrophy. mdx mice injected with a single dose of AAV9-CK8-microdystrophin or vehicle at age 7 weeks were assigned to three groups: mdxRGT (run, gene therapy), mdxGT (no run, gene therapy), or mdx (no run, no gene therapy). Wild-type (WT) mice were assigned to WTR (run) and WT (no run) groups. WTR and mdxRGT performed voluntary wheel running for 21 weeks; remaining groups were cage active. Robust expression of microdystrophin occurred in heart and limb muscles of treated mice. mdxRGT versus mdxGT mice showed increased microdystrophin in quadriceps but decreased levels in diaphragm. mdx final treadmill fatigue time was depressed compared to all groups, improved in mdxGT, and highest in mdxRGT. Both weekly running distance (km) and final treadmill fatigue time for mdxRGT and WTR were similar. Remarkably, mdxRGT diaphragm power was only rescued to 60% of WT, suggesting a negative impact of running. However, potential changes in fiber type distribution in mdxRGT diaphragms could indicate an adaptation to trade power for endurance. Post-treatment in vivo maximal plantar flexor torque relative to baseline values was greater for mdxGT and mdxRGT versus all other groups. Mitochondrial respiration rates from red quadriceps fibers were significantly improved in mdxGT animals, but the greatest bioenergetic benefit was observed in the mdxRGT group. Additional assessments revealed partial to full functional restoration in mdxGT and mdxRGT muscles relative to WT. These data demonstrate that voluntary wheel running combined with microdystrophin gene therapy in young mdx mice improved whole-body performance, affected muscle function differentially, mitigated energetic deficits, but also revealed some detrimental effects of exercise. With microdystrophin gene therapy currently in clinical trials, these data may help us understand the potential impact of exercise in treated patients.
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Affiliation(s)
- Shelby E Hamm
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Daniel D Fathalikhani
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Katherine E Bukovec
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Adele K Addington
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Haiyan Zhang
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Justin B Perry
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Ryan P McMillan
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | - Michael W Lawlor
- Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Mariah J Prom
- Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Mark A Vanden Avond
- Department of Pathology and Laboratory Medicine and Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Suresh N Kumar
- Department of Pathology and Laboratory Medicine and Children's Hospital of Wisconsin Research Institute Imaging Core, Milwaukee, WI 53226, USA
| | - Kirsten E Coleman
- Powell Gene Therapy Center Toxicology Core, University of Florida, Gainesville, FL 32610, USA
| | - J B Dupont
- Translational Gene Therapy for Genetic Diseases, INSERM UMR1089, IRS2 Nantes Biotech, Université de Nantes, Nantes 44200, France
| | - David L Mack
- Department of Rehabilitation Medicine, University of Washington, Seattle, WA 98104, USA.,Institute for Stem Cell and Regenerative Medicine, School of Medicine, University of Washington, Seattle, WA 98107, USA
| | - David A Brown
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
| | | | | | - Robert W Grange
- Department of Human Nutrition, Foods, and Exercise and Metabolism Core, Virginia Tech, Blacksburg, VA 24060, USA
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9
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Brennan S, Garcia-Castañeda M, Michelucci A, Sabha N, Malik S, Groom L, Wei LaPierre L, Dowling JJ, Dirksen RT. Mouse model of severe recessive RYR1-related myopathy. Hum Mol Genet 2020; 28:3024-3036. [PMID: 31107960 DOI: 10.1093/hmg/ddz105] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/07/2019] [Accepted: 05/13/2019] [Indexed: 12/16/2022] Open
Abstract
Ryanodine receptor type I (RYR1)-related myopathies (RYR1 RM) are a clinically and histopathologically heterogeneous group of conditions that represent the most common subtype of childhood onset non-dystrophic muscle disorders. There are no treatments for this severe group of diseases. A major barrier to therapy development is the lack of an animal model that mirrors the clinical severity of pediatric cases of the disease. To address this, we used CRISPR/Cas9 gene editing to generate a novel recessive mouse model of RYR1 RM. This mouse (Ryr1TM/Indel) possesses a patient-relevant point mutation (T4706M) engineered into 1 allele and a 16 base pair frameshift deletion engineered into the second allele. Ryr1TM/Indel mice exhibit an overt phenotype beginning at 14 days of age that consists of reduced body/muscle mass and myofibre hypotrophy. Ryr1TM/Indel mice become progressively inactive from that point onward and die at a median age of 42 days. Histopathological assessment shows myofibre hypotrophy, increased central nuclei and decreased triad number but no clear evidence of metabolic cores. Biochemical analysis reveals a marked decrease in RYR1 protein levels (20% of normal) as compared to only a 50% decrease in transcript. Functional studies at end stage show significantly reduced electrically evoked Ca2+ release and force production. In summary, Ryr1TM/Indel mice exhibit a post-natal lethal recessive form of RYR1 RM that pheno-copies the severe congenital clinical presentation seen in a subgroup of RYR1 RM children. Thus, Ryr1TM/Indel mice represent a powerful model for both establishing the pathomechanisms of recessive RYR1 RM and pre-clinical testing of therapies for efficacy.
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Affiliation(s)
- Stephanie Brennan
- Program for Genetics and Genome Biology, Hospital for Sick Children, 686 Bay St, Toronto, Ontario, M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, 686 Bay St, Toronto, Ontario, M5G 0A4, Canada
| | - Maricela Garcia-Castañeda
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642 USA
| | - Antonio Michelucci
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642 USA
| | - Nesrin Sabha
- Program for Genetics and Genome Biology, Hospital for Sick Children, 686 Bay St, Toronto, Ontario, M5G 0A4, Canada
| | - Sundeep Malik
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642 USA
| | - Linda Groom
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642 USA
| | - Lan Wei LaPierre
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642 USA
| | - James J Dowling
- Program for Genetics and Genome Biology, Hospital for Sick Children, 686 Bay St, Toronto, Ontario, M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, 686 Bay St, Toronto, Ontario, M5G 0A4, Canada.,Division of Neurology, Hospital for Sick Children, 686 Bay St, Toronto, Ontario, M5G 0A4, Canada
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642 USA
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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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11
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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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