1
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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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Huang K, Li Z, Zhong D, Yang Y, Yan X, Feng T, Wang X, Zhang L, Shen X, Chen M, Luo X, Cui K, Huang J, Rehman SU, Jiang Y, Shi D, Pauciullo A, Tang X, Liu Q, Li H. A Circular RNA Generated from Nebulin (NEB) Gene Splicing Promotes Skeletal Muscle Myogenesis in Cattle as Detected by a Multi-Omics Approach. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2300702. [PMID: 38036415 PMCID: PMC10797441 DOI: 10.1002/advs.202300702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 10/16/2023] [Indexed: 12/02/2023]
Abstract
Cattle and the draught force provided by its skeletal muscle have been integral to agro-ecosystems of agricultural civilization for millennia. However, relatively little is known about the cattle muscle functional genomics (including protein coding genes, non-coding RNA, etc.). Circular RNAs (circRNAs), as a new class of non-coding RNAs, can be effectively translated into detectable peptides, which enlightened us on the importance of circRNAs in cattle muscle physiology function. Here, RNA-seq, Ribosome profiling (Ribo-seq), and peptidome data are integrated from cattle skeletal muscle, and detected five encoded peptides from circRNAs. It is further identified and functionally characterize a 907-amino acids muscle-specific peptide that is named circNEB-peptide because derived by the splicing of Nebulin (NEB) gene. This peptide localizes to the nucleus and cytoplasm and directly interacts with SKP1 and TPM1, key factors regulating physiological activities of myoblasts, via ubiquitination and myoblast fusion, respectively. The circNEB-peptide is found to promote myoblasts proliferation and differentiation in vitro, and induce muscle regeneration in vivo. These findings suggest circNEB-peptide is an important regulator of skeletal muscle regeneration and underscore the possibility that more encoding polypeptides derived by RNAs currently annotated as non-coding exist.
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Affiliation(s)
- Kongwei Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and EngineeringFoshan UniversityFoshan528225China
- School of Biology and Biological EngineeringSouth China University of TechnologyGuangzhou510641China
| | - Zhipeng Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Dandan Zhong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Yufeng Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Xiuying Yan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Tong Feng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Xiaobo Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Liyin Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Xinyue Shen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Mengjie Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Xier Luo
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and EngineeringFoshan UniversityFoshan528225China
| | - Kuiqing Cui
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and EngineeringFoshan UniversityFoshan528225China
| | - Jieping Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Saif Ur Rehman
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Yu Jiang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and TechnologyNorthwest A&F UniversityYangling712100China
| | - Deshun Shi
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
| | - Alfredo Pauciullo
- Department of Agricultural, Forest and Food SciencesUniversity of TorinoGrugliasco (TO)10095Italy
| | - Xiangfang Tang
- State Key Laboratory of Animal Nutrition and Feeding,Institute of Animal SciencesChinese Academy of Agricultural SciencesBeijing100193China
| | - Qingyou Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and EngineeringFoshan UniversityFoshan528225China
| | - Hui Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and TechnologyGuangxi UniversityNanning530005China
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3
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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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Skrypnyk C, Husain AA, Hassan HY, Ahmed J, Darwish A, Almusalam L, Ben Khalaf N, Al Qashar F. Case report: Homozygous variants of NEB and KLHL40 in two Arab patients with nemaline myopathy. Front Genet 2023; 14:1098102. [PMID: 37025449 PMCID: PMC10070974 DOI: 10.3389/fgene.2023.1098102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/27/2023] [Indexed: 04/08/2023] Open
Abstract
Objective: Nemaline myopathies are a heterogeneous group of congenital myopathies caused by mutations in different genes associated with the structural and functional proteins of thin muscular filaments. Most patients have congenital onset characterized by hypotonia, respiratory issues, and abnormal deep tendon reflexes, which is a phenotype encountered in a wide spectrum of neuromuscular disorders. Whole-exome sequencing (WES) contributes to a faster diagnosis and facilitates genetic counseling. Methods: Here, we report on two Arab patients from consanguineous families diagnosed with nemaline myopathy of different phenotype spectrum severities. Results: Clinical assessment and particular prenatal history raised suspicion of neuromuscular disease. WES identified homozygous variants in NEB and KLHL40. Muscle biopsy and muscle magnetic resonance imaging studies linked the genetic testing results to the clinical phenotype. The novel variant in the NEB gene resulted in a classical type 2 nemaline myopathy, while the KLHL40 gene variant led to a severe phenotype of nemaline myopathy, type 8. Both patients were identified as having other gene variants with uncertain roles in their complex phenotypes. Conclusions: This study enriches the phenotypic spectrum of nemaline myopathy caused by NEB and KLHL40 variants and highlights the importance of detailed prenatal, neonatal, and infancy assessments of muscular weakness associated with complex systemic features. Variants of uncertain significance in genes associated with nemaline myopathy may be correlated with the phenotype. Early, multidisciplinary intervention can improve the outcome in patients with mild forms of nemaline myopathies. WES is essential for clarifying complex clinical phenotypes encountered in patients from consanguineous families. Targeted carrier screening of extended family members would enable accurate genetic counseling and potential genetic prevention.
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Affiliation(s)
- Cristina Skrypnyk
- Department of Molecular Medicine, Al‐Jawhara Centre for Molecular Medicine, Arabian Gulf University, Manama, Bahrain
- Department of Medical Genetics, University Medical Center, King Abdulla Medical City, Manama, Bahrain
- *Correspondence: Cristina Skrypnyk,
| | - Aseel Ahmed Husain
- Department of Pediatrics, Bahrain Defence Force Hospital, Royal Medical Services, Riffa, Bahrain
| | - Hisham Y. Hassan
- Banoon ART and Cytogenetics Centre, Bahrain Defence Force Hospital, Royal Medical Services, Riffa, Bahrain
| | - Jameel Ahmed
- Radiology Department, University Medical Center, King Abdulla Medical City, Manama, Bahrain
| | - Abdulla Darwish
- Department of Pathology, Bahrain Defence Force Hospital, Royal Medical Services, Riffa, Bahrain
| | - Latifa Almusalam
- Department of Pathology, Bahrain Defence Force Hospital, Royal Medical Services, Riffa, Bahrain
| | - Noureddine Ben Khalaf
- Life Sciences Department, Health Biotechnology Program, College of Graduate Studies, Arabian Gulf University, Manama, Bahrain
| | - Fahad Al Qashar
- Department of Pediatrics, Bahrain Defence Force Hospital, Royal Medical Services, Riffa, Bahrain
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5
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Functional genomics analysis reveals the evolutionary adaptation and demographic history of pygmy lorises. Proc Natl Acad Sci U S A 2022; 119:e2123030119. [PMID: 36161902 DOI: 10.1073/pnas.2123030119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lorises are a group of globally threatened strepsirrhine primates that exhibit many unusual physiological and behavioral features, including a low metabolic rate, slow movement, and hibernation. Here, we assembled a chromosome-level genome sequence of the pygmy loris (Xanthonycticebus pygmaeus) and resequenced whole genomes from 50 pygmy lorises and 6 Bengal slow lorises (Nycticebus bengalensis). We found that many gene families involved in detoxification have been specifically expanded in the pygmy loris, including the GSTA gene family, with many newly derived copies functioning specifically in the liver. We detected many genes displaying evolutionary convergence between pygmy loris and koala, including PITRM1. Significant decreases in PITRM1 enzymatic activity in these two species may have contributed to their characteristic low rate of metabolism. We also detected many evolutionarily convergent genes and positively selected genes in the pygmy loris that are involved in muscle development. Functional assays demonstrated the decreased ability of one positively selected gene, MYOF, to up-regulate the fast-type muscle fiber, consistent with the lower proportion of fast-twitch muscle fibers in the pygmy loris. The protein product of another positively selected gene in the pygmy loris, PER2, exhibited weaker binding to the key circadian core protein CRY, a finding that may be related to this species' unusual circadian rhythm. Finally, population genomics analysis revealed that these two extant loris species, which coexist in the same habitat, have exhibited an inverse relationship in terms of their demography over the past 1 million years, implying strong interspecies competition after speciation.
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6
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Liu D, Yu J, Wang X, Yang Y, Yu L, Zeng S, Zhang M, Xu G. Case Report: Prenatal Diagnosis of Nemaline Myopathy. Front Pediatr 2022; 10:937668. [PMID: 35928692 PMCID: PMC9343628 DOI: 10.3389/fped.2022.937668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/22/2022] [Indexed: 11/20/2022] Open
Abstract
Nemaline myopathy (NM) is a rare, hereditary heterogeneous myopathy. Fetal NM has a more severe disease course and a poorer prognosis and is usually lethal during the first few months of life. Hence, early prenatal diagnosis is especially important for clinical interventions and patient counseling. We report the case of a fetus with NM due to KLHL40 gene variation leading to arthrogryposis multiplex congenita (AMC). The ultrasonography and histopathology results revealed an enhanced echo intensity and decreased muscle thickness, which may be novel features providing early clues for the prenatal diagnosis of NM. Moreover, to our knowledge, this article is the first report to describe a case of NM associated with complex congenital heart disease (CHD).
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Affiliation(s)
- Dongmei Liu
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
| | - Jiali Yu
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
| | - Xin Wang
- Department of Obstetrics and Gynecology Prenatal Diagnosis Center, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yang Yang
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
| | - Li Yu
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
| | - Shi Zeng
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
| | - Ming Zhang
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
| | - Ganqiong Xu
- Department of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Center of Ultrasound Diagnostic, The Second Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Medical Imaging in Hunan Province, Changsha, China
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7
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Laitila J, Wallgren-Pettersson C. Recent advances in nemaline myopathy. Neuromuscul Disord 2021; 31:955-967. [PMID: 34561123 DOI: 10.1016/j.nmd.2021.07.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/18/2022]
Abstract
The nemaline myopathies constitute a large proportion of the congenital or structural myopathies. Common to all patients is muscle weakness and the presence in the muscle biopsy of nemaline rods. The causative genes are at least twelve, encoding structural or regulatory proteins of the thin filament, and the clinical picture as well as the histological appearance on muscle biopsy vary widely. Here, we suggest a renewed clinical classification to replace the original one, summarise what is known about the pathogenesis from mutations in each causative gene to the forms of nemaline myopathy described to date, and provide perspectives on pathogenetic mechanisms possibly open to therapeutic modalities.
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Affiliation(s)
- Jenni Laitila
- The Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Finland; Department of Biomedical Sciences, University of Copenhagen, Denmark.
| | - Carina Wallgren-Pettersson
- The Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Finland
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8
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Meunier J, Villar-Quiles RN, Duband-Goulet I, Ferreiro A. Inherited Defects of the ASC-1 Complex in Congenital Neuromuscular Diseases. Int J Mol Sci 2021; 22:ijms22116039. [PMID: 34204919 PMCID: PMC8199739 DOI: 10.3390/ijms22116039] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/19/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022] Open
Abstract
Defects in transcriptional and cell cycle regulation have emerged as novel pathophysiological mechanisms in congenital neuromuscular disease with the recent identification of mutations in the TRIP4 and ASCC1 genes, encoding, respectively, ASC-1 and ASCC1, two subunits of the ASC-1 (Activating Signal Cointegrator-1) complex. This complex is a poorly known transcriptional coregulator involved in transcriptional, post-transcriptional or translational activities. Inherited defects in components of the ASC-1 complex have been associated with several autosomal recessive phenotypes, including severe and mild forms of striated muscle disease (congenital myopathy with or without myocardial involvement), but also cases diagnosed of motor neuron disease (spinal muscular atrophy). Additionally, antenatal bone fractures were present in the reported patients with ASCC1 mutations. Functional studies revealed that the ASC-1 subunit is a novel regulator of cell cycle, proliferation and growth in muscle and non-muscular cells. In this review, we summarize and discuss the available data on the clinical and histopathological phenotypes associated with inherited defects of the ASC-1 complex proteins, the known genotype–phenotype correlations, the ASC-1 pathophysiological role, the puzzling question of motoneuron versus primary muscle involvement and potential future research avenues, illustrating the study of rare monogenic disorders as an interesting model paradigm to understand major physiological processes.
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Affiliation(s)
- Justine Meunier
- Basic and Translational Myology Laboratory, UMR8251, University of Paris/National Center for Scientific Research, 75013 Paris, France; (J.M.); (R.-N.V.-Q.)
| | - Rocio-Nur Villar-Quiles
- Basic and Translational Myology Laboratory, UMR8251, University of Paris/National Center for Scientific Research, 75013 Paris, France; (J.M.); (R.-N.V.-Q.)
- Reference Center for Neuromuscular Disorders, Pitié-Salpêtrière Hospital, APHP, Institute of Myology, 75013 Paris, France
| | - Isabelle Duband-Goulet
- Basic and Translational Myology Laboratory, UMR8251, University of Paris/National Center for Scientific Research, 75013 Paris, France; (J.M.); (R.-N.V.-Q.)
- Correspondence: (I.D.-G.); (A.F.); Tel.: +33-1-5727-7965 (I.D.-G.); +33-1-5727-7959 (A.F.)
| | - Ana Ferreiro
- Basic and Translational Myology Laboratory, UMR8251, University of Paris/National Center for Scientific Research, 75013 Paris, France; (J.M.); (R.-N.V.-Q.)
- Reference Center for Neuromuscular Disorders, Pitié-Salpêtrière Hospital, APHP, Institute of Myology, 75013 Paris, France
- Correspondence: (I.D.-G.); (A.F.); Tel.: +33-1-5727-7965 (I.D.-G.); +33-1-5727-7959 (A.F.)
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9
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Gohlke J, Tonino P, Lindqvist J, Smith JE, Granzier H. The number of Z-repeats and super-repeats in nebulin greatly varies across vertebrates and scales with animal size. J Gen Physiol 2020; 153:211611. [PMID: 33337482 PMCID: PMC7754682 DOI: 10.1085/jgp.202012783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/20/2020] [Indexed: 12/18/2022] Open
Abstract
Nebulin is a skeletal muscle protein that associates with the sarcomeric thin filaments and has functions in regulating the length of the thin filament and the structure of the Z-disk. Here we investigated the nebulin gene in 53 species of birds, fish, amphibians, reptiles, and mammals. In all species, nebulin has a similar domain composition that mostly consists of ∼30-residue modules (or simple repeats), each containing an actin-binding site. All species have a large region where simple repeats are organized into seven-module super-repeats, each containing a tropomyosin binding site. The number of super-repeats shows high interspecies variation, ranging from 21 (zebrafish, hummingbird) to 31 (camel, chimpanzee), and, importantly, scales with body size. The higher number of super-repeats in large animals was shown to increase thin filament length, which is expected to increase the sarcomere length for optimal force production, increase the energy efficiency of isometric force production, and lower the shortening velocity of muscle. It has been known since the work of A.V. Hill in 1950 that as species increase in size, the shortening velocity of their muscle is reduced, and the present work shows that nebulin contributes to the mechanistic basis. Finally, we analyzed the differentially spliced simple repeats in nebulin's C terminus, whose inclusion correlates with the width of the Z-disk. The number of Z-repeats greatly varies (from 5 to 18) and correlates with the number of super-repeats. We propose that the resulting increase in the width of the Z-disk in large animals increases the number of contacts between nebulin and structural Z-disk proteins when the Z-disk is stressed for long durations.
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Affiliation(s)
- Jochen Gohlke
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Paola Tonino
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - John E Smith
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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10
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A childhood-onset nemaline myopathy caused by novel heterozygote variants in the nebulin gene with literature review. Acta Neurol Belg 2020; 120:1351-1360. [PMID: 31696431 DOI: 10.1007/s13760-019-01230-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 10/17/2019] [Indexed: 10/25/2022]
Abstract
Nemaline myopathy, a rare congenital myopathy, is characterized by generalized muscle weakness, hypotonia, respiratory insufficiency, and the presence of rod structures on muscle biopsy, which is caused by mutations in at least 13 known genes. A patient showing gradually deteriorated proximal muscle weakness and rod-shaped structures found in muscle fibers was suspected of having nemaline myopathy, following by the next-generation sequencing. We report two novel compound heterozygous variants in nebulin gene in a family residing in China. One is an intron event caused by an underlying variant at the + 3 position of the donor site. Another is a novel nonsense variant, which may lead to the end of protein translation and have a significant impact on protein function. The pathogenicity of this novel compound heterozygous variant remains to be verified. Variants reported here could help to diagnose NM for clinicians.
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11
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Triggering typical nemaline myopathy with compound heterozygous nebulin mutations reveals myofilament structural changes as pathomechanism. Nat Commun 2020; 11:2699. [PMID: 32483185 PMCID: PMC7264197 DOI: 10.1038/s41467-020-16526-9] [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: 09/09/2019] [Accepted: 05/06/2020] [Indexed: 12/26/2022] Open
Abstract
Nebulin is a giant protein that winds around the actin filaments in the skeletal muscle sarcomere. Compound-heterozygous mutations in the nebulin gene (NEB) cause typical nemaline myopathy (NM), a muscle disorder characterized by muscle weakness with limited treatment options. We created a mouse model with a missense mutation p.Ser6366Ile and a deletion of NEB exon 55, the Compound-Het model that resembles typical NM. We show that Compound-Het mice are growth-retarded and have muscle weakness. Muscles have a reduced myofibrillar fractional-area and sarcomeres are disorganized, contain rod bodies, and have longer thin filaments. In contrast to nebulin-based severe NM where haplo-insufficiency is the disease driver, Compound-Het mice express normal amounts of nebulin. X-ray diffraction revealed that the actin filament is twisted with a larger radius, that tropomyosin and troponin behavior is altered, and that the myofilament spacing is increased. The unique disease mechanism of nebulin-based typical NM reveals novel therapeutic targets. Nebulin-based nemaline myopathy is a heterogenous disease with unclear pathological mechanisms. Here, the authors generate a mouse model that mimics the most common genetic cause of the disease and demonstrate that muscle weakness in this model is associated with twisted actin filaments and altered tropomyosin and troponin behaviour.
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12
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Laitila JM, McNamara EL, Wingate CD, Goullee H, Ross JA, Taylor RL, van der Pijl R, Griffiths LM, Harries R, Ravenscroft G, Clayton JS, Sewry C, Lawlor MW, Ottenheijm CAC, Bakker AJ, Ochala J, Laing NG, Wallgren-Pettersson C, Pelin K, Nowak KJ. Nebulin nemaline myopathy recapitulated in a compound heterozygous mouse model with both a missense and a nonsense mutation in Neb. Acta Neuropathol Commun 2020; 8:18. [PMID: 32066503 PMCID: PMC7027239 DOI: 10.1186/s40478-020-0893-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 02/05/2020] [Indexed: 12/31/2022] Open
Abstract
Nemaline myopathy (NM) caused by mutations in the gene encoding nebulin (NEB) accounts for at least 50% of all NM cases worldwide, representing a significant disease burden. Most NEB-NM patients have autosomal recessive disease due to a compound heterozygous genotype. Of the few murine models developed for NEB-NM, most are Neb knockout models rather than harbouring Neb mutations. Additionally, some models have a very severe phenotype that limits their application for evaluating disease progression and potential therapies. No existing murine models possess compound heterozygous Neb mutations that reflect the genotype and resulting phenotype present in most patients. We aimed to develop a murine model that more closely matched the underlying genetics of NEB-NM, which could assist elucidation of the pathogenetic mechanisms underlying the disease. Here, we have characterised a mouse strain with compound heterozygous Neb mutations; one missense (p.Tyr2303His), affecting a conserved actin-binding site and one nonsense mutation (p.Tyr935*), introducing a premature stop codon early in the protein. Our studies reveal that this compound heterozygous model, NebY2303H, Y935X, has striking skeletal muscle pathology including nemaline bodies. In vitro whole muscle and single myofibre physiology studies also demonstrate functional perturbations. However, no reduction in lifespan was noted. Therefore, NebY2303H,Y935X mice recapitulate human NEB-NM and are a much needed addition to the NEB-NM mouse model collection. The moderate phenotype also makes this an appropriate model for studying NEB-NM pathogenesis, and could potentially be suitable for testing therapeutic applications.
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13
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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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14
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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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15
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Gineste C, Ogier AC, Varlet I, Hourani Z, Bernard M, Granzier H, Bendahan D, Gondin J. In vivo characterization of skeletal muscle function in nebulin-deficient mice. Muscle Nerve 2020; 61:416-424. [PMID: 31893464 DOI: 10.1002/mus.26798] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 12/16/2019] [Accepted: 12/21/2019] [Indexed: 01/04/2023]
Abstract
INTRODUCTION The conditional nebulin knockout mouse is a new model mimicking nemaline myopathy, a rare disease characterized by muscle weakness and rods within muscle fibers. We investigated the impact of nebulin (NEB) deficiency on muscle function in vivo. METHODS Conditional nebulin knockout mice and control littermates were studied at 10 to 12 months. Muscle function (force and fatigue) and anatomy (muscles volume and fat content) were measured in vivo. Myosin heavy chain (MHC) composition and nebulin (NEB) protein expression were assessed by protein electrophoresis. RESULTS Conditional nebulin knockout mice displayed a lower NEB level (-90%) leading to a 40% and 45% reduction in specific maximal force production and muscles volume, respectively. Nebulin deficiency was also associated with higher resistance to fatigue and increased MHC I content. DISCUSSION Adult nebulin-deficient mice displayed severe muscle atrophy and weakness in vivo related to a low NEB content but an improved fatigue resistance due to a slower contractile phenotype.
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Affiliation(s)
| | - Augustin C Ogier
- Aix Marseille Univ, Université de Toulon, CNRS, LIS, Marseille, France
| | | | - Zaynab Hourani
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | | | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | | | - Julien Gondin
- Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.,Institut NeuroMyoGène, UMR CNRS 5310 - INSERM U1217, Université Claude Bernard, Lyon, France
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16
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Tinklenberg JA, Siebers EM, Beatka MJ, Fickau BA, Ayres S, Meng H, Yang L, Simpson P, Granzier HL, Lawlor MW. Myostatin Inhibition Using ActRIIB-mFc Does Not Produce Weight Gain or Strength in the Nebulin Conditional KO Mouse. J Neuropathol Exp Neurol 2019; 78:130-139. [PMID: 30597051 DOI: 10.1093/jnen/nly120] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mutations in at least 12 genes are responsible for a group of congenital skeletal muscle diseases known as nemaline myopathies (NMs). NMs are associated with a range of clinical symptoms and pathological changes often including the presence of cytoplasmic rod-like structures (nemaline bodies) and myofiber hypotrophy. Our recent work has identified a variable degree of behavioral benefit when treating 2 NM mouse models due to mutations in Acta1 with myostatin inhibition. This study is focused on the effects of delivering ActRIIB-mFc (Acceleron; a myostatin inhibitor) to the nebulin conditional knockout KO (Neb cKO) mouse model of NM. Treatment of Neb cKO mice with ActRIIB-mFc did not produce increases in weight gain, strength, myofiber size, or hypertrophic pathway signaling. Overall, our studies demonstrate a lack of response in Neb cKO mice to myostatin inhibition, which differs from the response observed when treating other NM models.
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Affiliation(s)
- Jennifer A Tinklenberg
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine.,Neuroscience Research Center Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Emily M Siebers
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine.,Neuroscience Research Center Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Margaret J Beatka
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine.,Neuroscience Research Center Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Brittany A Fickau
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine.,Neuroscience Research Center Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Samuel Ayres
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine.,Neuroscience Research Center Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Hui Meng
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine
| | - Lin Yang
- Department of Biomedical Engineering, University of Florida, Gainesville, Florida
| | - Pippa Simpson
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine
| | - Henk L Granzier
- Division of Quantitative Health Sciences, Department of Pediatrics Medical College of Wisconsin, Milwaukee, Wisconsin (PS); and College of Medicine, University of Arizona, Tucson, Arizona
| | - Michael W Lawlor
- Division of Pediatric Pathology, Department of Pathology and Laboratory Medicine.,Neuroscience Research Center Medical College of Wisconsin, Milwaukee, Wisconsin
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17
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Lindqvist J, Lee EJ, Karimi E, Kolb J, Granzier H. Omecamtiv mecarbil lowers the contractile deficit in a mouse model of nebulin-based nemaline myopathy. PLoS One 2019; 14:e0224467. [PMID: 31721788 PMCID: PMC6853306 DOI: 10.1371/journal.pone.0224467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 10/14/2019] [Indexed: 01/10/2023] Open
Abstract
Nemaline myopathy (NEM) is a congenital neuromuscular disorder primarily caused by nebulin gene (NEB) mutations. NEM is characterized by muscle weakness for which currently no treatments exist. In NEM patients a predominance of type I fibers has been found. Thus, therapeutic options targeting type I fibers could be highly beneficial for NEM patients. Because type I muscle fibers express the same myosin isoform as cardiac muscle (Myh7), the effect of omecamtiv mecarbil (OM), a small molecule activator of Myh7, was studied in a nebulin-based NEM mouse model (Neb cKO). Skinned single fibers were activated by exogenous calcium and force was measured at a wide range of calcium concentrations. Maximal specific force of type I fibers was much less in fibers from Neb cKO animals and calcium sensitivity of permeabilized single fibers was reduced (pCa50 6.12 ±0.08 (cKO) vs 6.36 ±0.08 (CON)). OM increased the calcium sensitivity of type I single muscle fibers. The greatest effect occurred in type I fibers from Neb cKO muscle where OM restored the calcium sensitivity to that of the control type I fibers. Forces at submaximal activation levels (pCa 6.0–6.5) were significantly increased in Neb cKO fibers (~50%) but remained below that of control fibers. OM also increased isometric force and power during isotonic shortening of intact whole soleus muscle of Neb cKO mice, with the largest effects at physiological stimulation frequencies. We conclude that OM has the potential to improve the quality of life of NEM patients by increasing the force of type I fibers at submaximal activation levels.
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Affiliation(s)
- Johan Lindqvist
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Eun-Jeong Lee
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Esmat Karimi
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Justin Kolb
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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18
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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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19
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Mijailovich SM, Stojanovic B, Nedic D, Svicevic M, Geeves MA, Irving TC, Granzier HL. Nebulin and titin modulate cross-bridge cycling and length-dependent calcium sensitivity. J Gen Physiol 2019; 151:680-704. [PMID: 30948421 PMCID: PMC6504291 DOI: 10.1085/jgp.201812165] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 01/15/2019] [Accepted: 03/03/2019] [Indexed: 12/13/2022] Open
Abstract
Various mutations in the structural proteins nebulin and titin that are present in human disease are known to affect the contractility of striated muscle. Loss of nebulin is associated with reduced actin filament length and impairment of myosin binding to actin, whereas titin is thought to regulate muscle passive elasticity and is likely involved in length-dependent activation. Here, we sought to assess the modulation of muscle function by these sarcomeric proteins by using the computational platform muscle simulation code (MUSICO) to quantitatively separate the effects of structural changes, kinetics of cross-bridge cycling, and calcium sensitivity of the thin filaments. The simulations show that variation in thin filament length cannot by itself account for experimental observations of the contractility in nebulin-deficient muscle, but instead must be accompanied by a decreased myosin binding rate. Additionally, to match the observed calcium sensitivity, the rate of TnI detachment from actin needed to be increased. Simulations for cardiac muscle provided quantitative estimates of the effects of different titin-based passive elasticities on muscle force and activation in response to changes in sarcomere length and interfilament lattice spacing. Predicted force-pCa relations showed a decrease in both active tension and sensitivity to calcium with a decrease in passive tension and sarcomere length. We conclude that this behavior is caused by partial redistribution of the muscle load between active muscle force and titin-dependent passive force, and also by redistribution of stretch along the thin filament, which together modulate the release of TnI from actin. These data help advance understanding of how nebulin and titin mutations affect muscle function.
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Affiliation(s)
- Srboljub M Mijailovich
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA .,Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
| | - Boban Stojanovic
- University of Kragujevac, Faculty of Science, Kragujevac, Serbia
| | - Djordje Nedic
- University of Kragujevac, Faculty of Science, Kragujevac, Serbia
| | - Marina Svicevic
- University of Kragujevac, Faculty of Science, Kragujevac, Serbia
| | - Michael A Geeves
- Department of Biosciences, University of Kent, Canterbury, Kent, UK
| | - Thomas C Irving
- Department of Biological Sciences, Illinois Institute of Technology, Chicago, IL
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20
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Fox MD, Carson VJ, Feng HZ, Lawlor MW, Gray JT, Brigatti KW, Jin JP, Strauss KA. TNNT1 nemaline myopathy: natural history and therapeutic frontier. Hum Mol Genet 2019; 27:3272-3282. [PMID: 29931346 DOI: 10.1093/hmg/ddy233] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/06/2018] [Indexed: 02/03/2023] Open
Abstract
We describe the natural history of 'Amish' nemaline myopathy (ANM), an infantile-onset, lethal disease linked to a pathogenic c.505G>T nonsense mutation of TNNT1, which encodes the slow fiber isoform of troponin T (TNNT1; a.k.a. TnT). The TNNT1 c.505G>T allele has a carrier frequency of 6.5% within Old Order Amish settlements of North America. We collected natural history data for 106 ANM patients born between 1923 and 2017. Over the last two decades, mean age of molecular diagnosis was 16 ± 27 days. TNNT1 c.505G>T homozygotes were normal weight at birth but failed to thrive by age 9 months. Presenting neonatal signs were axial hypotonia, hip and shoulder stiffness, and tremors, followed by progressive muscle weakness, atrophy and contractures. Affected children developed thoracic rigidity, pectus carinatum and restrictive lung disease during infancy, and all succumbed to respiratory failure by 6 years of age (median survival 18 months, range 0.2-66 months). Muscle histology from two affected children showed marked fiber size variation owing to both Type 1 myofiber smallness (hypotrophy) and Type 2 fiber hypertrophy, with evidence of nemaline rods, myofibrillar disarray and vacuolar pathology in both fiber types. The truncated slow TNNT1 (TnT) fragment (p.Glu180Ter) was undetectable in ANM muscle, reflecting its rapid proteolysis and clearance from sarcoplasm. Similar functional and histological phenotypes were observed in other human cohorts and two transgenic murine models (Tnnt1-/- and Tnnt1 c.505G>T). These findings have implications for emerging molecular therapies, including the suitably of TNNT1 gene replacement for newborns with ANM or other TNNT1-associated myopathies.
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Affiliation(s)
- Michael D Fox
- Clinic for Special Children, Strasburg, PA, USA
- Department of Pediatrics, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA
- Diagnostic Referral Division, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | | | - Han-Zhong Feng
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Michael W Lawlor
- Department of Pathology and Laboratory Medicine and Neuroscience Research Center, The Medical College of Wisconsin, Milwaukee, WI, USA
| | - John T Gray
- Audentes Therapeutics, San Francisco, CA, USA
| | | | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
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21
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Lindqvist J, van den Berg M, van der Pijl R, Hooijman PE, Beishuizen A, Elshof J, de Waard M, Girbes A, Spoelstra-de Man A, Shi ZH, van den Brom C, Bogaards S, Shen S, Strom J, Granzier H, Kole J, Musters RJP, Paul MA, Heunks LMA, Ottenheijm CAC. Positive End-Expiratory Pressure Ventilation Induces Longitudinal Atrophy in Diaphragm Fibers. Am J Respir Crit Care Med 2018; 198:472-485. [PMID: 29578749 PMCID: PMC6118031 DOI: 10.1164/rccm.201709-1917oc] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 03/26/2018] [Indexed: 01/11/2023] Open
Abstract
RATIONALE Diaphragm weakness in critically ill patients prolongs ventilator dependency and duration of hospital stay and increases mortality and healthcare costs. The mechanisms underlying diaphragm weakness include cross-sectional fiber atrophy and contractile protein dysfunction, but whether additional mechanisms are at play is unknown. OBJECTIVES To test the hypothesis that mechanical ventilation with positive end-expiratory pressure (PEEP) induces longitudinal atrophy by displacing the diaphragm in the caudal direction and reducing the length of fibers. METHODS We studied structure and function of diaphragm fibers of mechanically ventilated critically ill patients and mechanically ventilated rats with normal and increased titin compliance. MEASUREMENTS AND MAIN RESULTS PEEP causes a caudal movement of the diaphragm, both in critically ill patients and in rats, and this caudal movement reduces fiber length. Diaphragm fibers of 18-hour mechanically ventilated rats (PEEP of 2.5 cm H2O) adapt to the reduced length by absorbing serially linked sarcomeres, the smallest contractile units in muscle (i.e., longitudinal atrophy). Increasing the compliance of titin molecules reduces longitudinal atrophy. CONCLUSIONS Mechanical ventilation with PEEP results in longitudinal atrophy of diaphragm fibers, a response that is modulated by the elasticity of the giant sarcomeric protein titin. We postulate that longitudinal atrophy, in concert with the aforementioned cross-sectional atrophy, hampers spontaneous breathing trials in critically ill patients: during these efforts, end-expiratory lung volume is reduced, and the shortened diaphragm fibers are stretched to excessive sarcomere lengths. At these lengths, muscle fibers generate less force, and diaphragm weakness ensues.
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Affiliation(s)
- Johan Lindqvist
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | | | - Robbert van der Pijl
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- Department of Physiology
| | | | - Albertus Beishuizen
- Department of Intensive Care, Medisch Spectrum Twente, Enschede, the Netherlands; and
| | | | | | | | | | - Zhong-Hua Shi
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, PR China
| | | | | | - Shengyi Shen
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Joshua Strom
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | - Henk Granzier
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
| | | | | | - Marinus A. Paul
- Department of Cardiothoracic Surgery, Vrije Universiteit Medical Center, Amsterdam, the Netherlands
| | | | - Coen A. C. Ottenheijm
- Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona
- Department of Physiology
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22
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Wunderlich G, Brunn A, Daimagüler HS, Bozoglu T, Fink GR, Lehmann HC, Weis J, Cirak S. Long term history of a congenital core-rod myopathy with compound heterozygous mutations in the Nebulin gene. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2018; 37:121-127. [PMID: 30057997 PMCID: PMC6060425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Mutations in the Nebulin gene (NEB) may cause core-rod myopathy. The large size of the gene so far prevented inclusion of its routine analysis by didesoxy resequencing methodology in the diagnostic regime for muscular dystrophy cases. Here we report a 54-year-old female with a rare histological myopathy presentation of co-occurring cores and rods. The patient reported early childhood onset weakness. Muscle-MRI showed mainly proximal muscle involvement. We identified two compound heterozygous non-sense mutations in NEB (c.19653G > A, p.W6551* exon 127 and c.25441C > T, p.R8481* exon 182) using a comprehensive next generation sequencing (NGS)-based approach named Mendeliome Sequencing. The p.W6551* mutation has not been reported elsewhere. Early diagnosis by NGS shall be chased since even a scoliosis surgery at the age of 18 years had failed to initiate a neurological workup. Rather, cosmetic surgery for facial weakness had been performed recently, albeit with an unsatisfactory outcome.
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Affiliation(s)
- Gilbert Wunderlich
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany
| | - Anna Brunn
- Institute for Neuropathology, University of Cologne, 50937 Cologne, Germany
| | - Hülya-Sevcan Daimagüler
- Department of Pediatrics, University Hospital Cologne, 50937 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Tarik Bozoglu
- Department of Pediatrics, University Hospital Cologne, 50937 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
| | - Gereon R. Fink
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany
- Cognitive Neuroscience, Institute of Neuroscience and Medicine, Research Centre Jülich, 52428 Jülich, Germany
| | - Helmar C. Lehmann
- Department of Neurology, University Hospital Cologne, 50937 Cologne, Germany
| | - Joachim Weis
- Institute for Neuropathology, RWTH University Hospital Aachen, 52074 Aachen, Germany
| | - Sebahattin Cirak
- Department of Pediatrics, University Hospital Cologne, 50937 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50931 Cologne, Germany
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23
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Ahmed AA, Skaria P, Safina NP, Thiffault I, Kats A, Taboada E, Habeebu S, Saunders C. Arthrogryposis and pterygia as lethal end manifestations of genetically defined congenital myopathies. Am J Med Genet A 2017; 176:359-367. [DOI: 10.1002/ajmg.a.38577] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 11/16/2017] [Accepted: 11/17/2017] [Indexed: 12/16/2022]
Affiliation(s)
- Atif A. Ahmed
- Department of PathologyChildren's Mercy HospitalKansas CityMissouri
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
| | - Priya Skaria
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
| | - Nicole P. Safina
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
- Center for Pediatric Genomic MedicineChildren's Mercy HospitalKansas CityMissouri
- Division of Clinical GeneticsChildren's Mercy HospitalKansas CityMissouri
| | - Isabelle Thiffault
- Department of PathologyChildren's Mercy HospitalKansas CityMissouri
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
- Center for Pediatric Genomic MedicineChildren's Mercy HospitalKansas CityMissouri
| | - Alex Kats
- Department of PathologyChildren's Mercy HospitalKansas CityMissouri
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
| | - Eugenio Taboada
- Department of PathologyChildren's Mercy HospitalKansas CityMissouri
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
| | - Sultan Habeebu
- Department of PathologyChildren's Mercy HospitalKansas CityMissouri
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
| | - Carol Saunders
- Department of PathologyChildren's Mercy HospitalKansas CityMissouri
- University of Missouri‐Kansas City School of MedicineKansas CityMissouri
- Center for Pediatric Genomic MedicineChildren's Mercy HospitalKansas CityMissouri
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24
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Lee JM, Lim JG, Shin JH, Park YE, Kim DS. Clinical and genetic diversity of nemaline myopathy from a single neuromuscular center in Korea. J Neurol Sci 2017; 383:61-68. [PMID: 29246625 DOI: 10.1016/j.jns.2017.10.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/19/2017] [Accepted: 10/09/2017] [Indexed: 11/17/2022]
Abstract
Nemaline myopathy (NM), the most common of the congenital myopathies, is caused by various genetic mutations. In this study, we attempted to identify the causative mutations of NM and to reveal any specific genotype-phenotype relationship in Korean patients with this disease. We investigated the clinical features and genotypes in 15 pathologically diagnosed NM patients, using whole exome sequencing (WES) combined with targeted sequencing and array-based comparative genomic hybridization. This strategy revealed pathogenic causative mutations in seven patients (46.7%), among whom mutations in the nebulin gene (NEB) were the most frequent (5 patients, 33.3%). Copy number variation (CNV) abnormality in NEB was not observed in any of our patients. In those with NEB-associated NM, the clinical spectrum was highly variable regardless of the mutation type. However, the majority of patients showing anterior lower leg weakness were associated with mutations located between NEB exons 166 and 177. We concluded that the combination of WES and targeted Sanger sequencing is an effective strategy for analyzing genotypes in patients with NM, and that CNV in NEB may not be a frequent cause of this disease among Koreans.
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Affiliation(s)
- Jong-Mok Lee
- Department of Neurology, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Republic of Korea
| | - Jeong Geun Lim
- Department of Neurology, Keimyung University School of Medicine, Republic of Korea
| | - Jin-Hong Shin
- Department of Neurology, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Republic of Korea
| | - Young-Eun Park
- Department of Neurology, Pusan National University School of Medicine, Republic of Korea
| | - Dae-Seong Kim
- Department of Neurology, Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Republic of Korea; Department of Neurology, Pusan National University School of Medicine, Republic of Korea.
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25
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Feingold-Zadok M, Chitayat D, Chong K, Injeyan M, Shannon P, Chapmann D, Maymon R, Pillar N, Reish O. Mutations in the NEB
gene cause fetal akinesia/arthrogryposis multiplex congenita. Prenat Diagn 2017; 37:144-150. [DOI: 10.1002/pd.4977] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Michal Feingold-Zadok
- Genetic Institute; Assaf Harofeh Medical Center; Zerifin Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
- Department of Obstetrics and Gynecology Ward, Ultrasound Unit; Assaf Harofeh Medical Center; Zerifin Israel
| | - David Chitayat
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and gynecology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Karen Chong
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and gynecology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Marie Injeyan
- Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and gynecology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Patrick Shannon
- Department of Laboratory Medicine and Pathobiology, Mount Sinai Hospital; University of Toronto; Toronto Ontario Canada
| | - Daphne Chapmann
- Genetic Institute; Assaf Harofeh Medical Center; Zerifin Israel
| | - Ron Maymon
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
- Department of Obstetrics and Gynecology Ward, Ultrasound Unit; Assaf Harofeh Medical Center; Zerifin Israel
| | - Nir Pillar
- Bioinformatic Division, Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
| | - Orit Reish
- Genetic Institute; Assaf Harofeh Medical Center; Zerifin Israel
- Sackler School of Medicine; Tel Aviv University; Tel Aviv Israel
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26
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Tsunoda K, Yamashita T, Motokura E, Takahashi Y, Sato K, Takemoto M, Hishikawa N, Ohta Y, Nishikawa A, Nishino I, Abe K. A patient with slowly progressive adult-onset nemaline myopathy and novel compound heterozygous mutations in the nebulin gene. J Neurol Sci 2016; 373:254-257. [PMID: 28131200 DOI: 10.1016/j.jns.2016.12.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/25/2016] [Accepted: 12/29/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Keiichiro Tsunoda
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Toru Yamashita
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Emi Motokura
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Yoshiaki Takahashi
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Kota Sato
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Mami Takemoto
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Nozomi Hishikawa
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Yasuyuki Ohta
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan
| | - Atsuko Nishikawa
- National Center of Neurology and Psychiatry, 4-1-1 Kodaira, Tokyo 187-8502, Japan
| | - Ichizo Nishino
- National Center of Neurology and Psychiatry, 4-1-1 Kodaira, Tokyo 187-8502, Japan
| | - Koji Abe
- Department of Neurology, Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Okayama 700-8558, Japan.
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27
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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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28
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Park YE, Shin JH, Kang B, Lee CH, Kim DS. NEB-related core-rod myopathy with distinct clinical and pathological features. Muscle Nerve 2016; 53:479-84. [PMID: 26562614 DOI: 10.1002/mus.24966] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2015] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Mutations in the gene encoding nebulin (NEB) are known to cause several types of congenital myopathy including recessive nemaline myopathy and distal nebulin myopathy. Core-rod myopathy has recently been reported to be another type of NEB-related myopathy, and is pathologically characterized by the coexistence of cores and nemaline rods within muscle fibers. METHODS We describe 2 patients with core-rod myopathy who were analyzed genetically by whole exome sequencing and evaluated clinically and pathologically. Findings were compared with those of patients with the disease of other genetic causes. RESULTS Three NEB mutations were identified, 2 of which were novel. Mild clinical features, unusual patterns of muscle involvement, and atypical pathological findings were observed. CONCLUSIONS We propose that the clinical and pathological spectrum of core-rod myopathy should be widened. A significant amount of residual nebulin expression is believed to contribute to the much milder phenotype exhibited by the patients we describe here.
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Affiliation(s)
- Young-Eun Park
- Department of Neurology, Pusan National University Yangsan Hospital, Beomo-ri, Mulgeum-eup, Yangsan, 626-770, Gyeongnam, South Korea.,Biomedical Research Institute, Pusan National University Hospital, Busan, South Korea
| | - Jin-Hong Shin
- Department of Neurology, Pusan National University Yangsan Hospital, Beomo-ri, Mulgeum-eup, Yangsan, 626-770, Gyeongnam, South Korea.,Research Institute for Convergence of Biomedical Research and Technology, Pusan National University Yangsan Hospital, Gyeongnam, South Korea
| | - Boram Kang
- Research Institute for Convergence of Biomedical Research and Technology, Pusan National University Yangsan Hospital, Gyeongnam, South Korea
| | - Chang-Hoon Lee
- Biomedical Research Institute, Pusan National University Hospital, Busan, South Korea.,Department of Pathology, Pusan National University, Busan, South Korea
| | - Dae-Seong Kim
- Department of Neurology, Pusan National University Yangsan Hospital, Beomo-ri, Mulgeum-eup, Yangsan, 626-770, Gyeongnam, South Korea.,Research Institute for Convergence of Biomedical Research and Technology, Pusan National University Yangsan Hospital, Gyeongnam, South Korea
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29
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Lehtokari VL, Kiiski K, Sandaradura SA, Laporte J, Repo P, Frey JA, Donner K, Marttila M, Saunders C, Barth PG, den Dunnen JT, Beggs AH, Clarke NF, North KN, Laing NG, Romero NB, Winder TL, Pelin K, Wallgren-Pettersson C. Mutation update: the spectra of nebulin variants and associated myopathies. Hum Mutat 2015; 35:1418-26. [PMID: 25205138 DOI: 10.1002/humu.22693] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 08/29/2014] [Indexed: 12/23/2022]
Abstract
A mutation update on the nebulin gene (NEB) is necessary because of recent developments in analysis methodology, the identification of increasing numbers and novel types of variants, and a widening in the spectrum of clinical and histological phenotypes associated with this gigantic, 183 exons containing gene. Recessive pathogenic variants in NEB are the major cause of nemaline myopathy (NM), one of the most common congenital myopathies. Moreover, pathogenic NEB variants have been identified in core-rod myopathy and in distal myopathies. In this update, we present the disease-causing variants in NEB in 159 families, 143 families with NM, and 16 families with NM-related myopathies. Eighty-eight families are presented here for the first time. We summarize 86 previously published and 126 unpublished variants identified in NEB. Furthermore, we have analyzed the NEB variants deposited in the Exome Variant Server (http://evs.gs.washington.edu/EVS/), identifying that pathogenic variants are a minor fraction of all coding variants (∼7%). This indicates that nebulin tolerates substantial changes in its amino acid sequence, providing an explanation as to why variants in such a large gene result in relatively rare disorders. Lastly, we discuss the difficulties of drawing reliable genotype-phenotype correlations in NEB-associated disease.
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Affiliation(s)
- Vilma-Lotta Lehtokari
- The Folkhälsan Institute of Genetics and the Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
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30
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Li F, Buck D, De Winter J, Kolb J, Meng H, Birch C, Slater R, Escobar YN, Smith JE, Yang L, Konhilas J, Lawlor MW, Ottenheijm C, Granzier HL. Nebulin deficiency in adult muscle causes sarcomere defects and muscle-type-dependent changes in trophicity: novel insights in nemaline myopathy. Hum Mol Genet 2015; 24:5219-33. [PMID: 26123491 DOI: 10.1093/hmg/ddv243] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/22/2015] [Indexed: 01/07/2023] Open
Abstract
Nebulin is a giant filamentous protein that is coextensive with the actin filaments of the skeletal muscle sarcomere. Nebulin mutations are the main cause of nemaline myopathy (NEM), with typical adult patients having low expression of nebulin, yet the roles of nebulin in adult muscle remain poorly understood. To establish nebulin's functional roles in adult muscle, we studied a novel conditional nebulin KO (Neb cKO) mouse model in which nebulin deletion was driven by the muscle creatine kinase (MCK) promotor. Neb cKO mice are born with high nebulin levels in their skeletal muscles, but within weeks after birth nebulin expression rapidly falls to barely detectable levels Surprisingly, a large fraction of the mice survive to adulthood with low nebulin levels (<5% of control), contain nemaline rods and undergo fiber-type switching toward oxidative types. Nebulin deficiency causes a large deficit in specific force, and mechanistic studies provide evidence that a reduced fraction of force-generating cross-bridges and shortened thin filaments contribute to the force deficit. Muscles rich in glycolytic fibers upregulate proteolysis pathways (MuRF-1, Fbxo30/MUSA1, Gadd45a) and undergo hypotrophy with smaller cross-sectional areas (CSAs), worsening their force deficit. Muscles rich in oxidative fibers do not have smaller weights and can even have hypertrophy, offsetting their specific-force deficit. These studies reveal nebulin as critically important for force development and trophicity in adult muscle. The Neb cKO phenocopies important aspects of NEM (muscle weakness, oxidative fiber-type predominance, variable trophicity effects, nemaline rods) and will be highly useful to test therapeutic approaches to ameliorate muscle weakness.
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Affiliation(s)
- Frank Li
- Department of Cellular and Molecular Medicine
| | | | - Josine De Winter
- Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands
| | - Justin Kolb
- Department of Cellular and Molecular Medicine
| | - Hui Meng
- Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, Milwaukee, WI, USA and
| | - Camille Birch
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | | | | | | | - Lin Yang
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - John Konhilas
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Michael W Lawlor
- Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, Milwaukee, WI, USA and
| | - Coen Ottenheijm
- Department of Cellular and Molecular Medicine, Department of Physiology, VU University Medical Center, Amsterdam, The Netherlands
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31
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de Winter JM, Joureau B, Sequeira V, Clarke NF, van der Velden J, Stienen GJ, Granzier H, Beggs AH, Ottenheijm CA. Effect of levosimendan on the contractility of muscle fibers from nemaline myopathy patients with mutations in the nebulin gene. Skelet Muscle 2015; 5:12. [PMID: 25949787 PMCID: PMC4422316 DOI: 10.1186/s13395-015-0037-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/01/2015] [Indexed: 11/25/2022] Open
Abstract
Background Nemaline myopathy (NM), the most common non-dystrophic congenital myopathy, is characterized by generalized skeletal muscle weakness, often from birth. To date, no therapy exists that enhances the contractile strength of muscles of NM patients. Mutations in NEB, encoding the giant protein nebulin, are the most common cause of NM. The pathophysiology of muscle weakness in NM patients with NEB mutations (NEB-NM) includes a lower calcium-sensitivity of force generation. We propose that the lower calcium-sensitivity of force generation in NEB-NM offers a therapeutic target. Levosimendan is a calcium sensitizer that is approved for use in humans and has been developed to target cardiac muscle fibers. It exerts its effect through binding to slow skeletal/cardiac troponin C. As slow skeletal/cardiac troponin C is also the dominant troponin C isoform in slow-twitch skeletal muscle fibers, we hypothesized that levosimendan improves slow-twitch muscle fiber strength at submaximal levels of activation in patients with NEB-NM. Methods To test whether levosimendan affects force production, permeabilized slow-twitch muscle fibers isolated from biopsies of NEB-NM patients and controls were exposed to levosimendan and the force response was measured. Results No effect of levosimendan on muscle fiber force in NEB-NM and control skeletal muscle fibers was found, both at a submaximal calcium level using incremental levosimendan concentrations, and at incremental calcium concentrations in the presence of levosimendan. In contrast, levosimendan did significantly increase the calcium-sensitivity of force in human single cardiomyocytes. Protein analysis confirmed that the slow skeletal/cardiac troponin C isoform was present in the skeletal muscle fibers tested. Conclusions These findings indicate that levosimendan does not improve the contractility in human skeletal muscle fibers, and do not provide rationale for using levosimendan as a therapeutic to restore muscle weakness in NEB-NM patients. We stress the importance of searching for compounds that improve the calcium-sensitivity of force generation of slow-twitch muscle fibers. Such compounds provide an appealing approach to restore muscle force in patients with NEB-NM, and also in patients with other neuromuscular disorders. Electronic supplementary material The online version of this article (doi:10.1186/s13395-015-0037-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Josine M de Winter
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, De Boelelaan 1118, 1081, BT Amsterdam, The Netherlands
| | - Barbara Joureau
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, De Boelelaan 1118, 1081, BT Amsterdam, The Netherlands
| | - Vasco Sequeira
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, De Boelelaan 1118, 1081, BT Amsterdam, The Netherlands
| | - Nigel F Clarke
- INMR, The Children's Hospital at Westmead and Discipline of Paediatrics & Child Health, University of Sydney, Cnr Hawkesbury Road & Hainsworth Street, Sydney, Australia
| | - Jolanda van der Velden
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, De Boelelaan 1118, 1081, BT Amsterdam, The Netherlands
| | - Ger Jm Stienen
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, De Boelelaan 1118, 1081, BT Amsterdam, The Netherlands ; Department of Physics and Astronomy, Faculty of Science, VU University, De Boelelaan 1105, Amsterdam, The Netherlands
| | - Henk Granzier
- Department of Cellular and Molecular Medicine, University of Arizona, 1333 N. Martin Avenue, Tucson, USA
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, 25 Shattuck Street, Boston, USA
| | - Coen Ac Ottenheijm
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, De Boelelaan 1118, 1081, BT Amsterdam, The Netherlands ; Department of Cellular and Molecular Medicine, University of Arizona, 1333 N. Martin Avenue, Tucson, USA
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Abstract
Various human diseases can disrupt the balance between muscle contraction and relaxation. Sarcomeric modulators can be used to readjust this balance either indirectly by intervening in signalling pathways or directly through interaction with the muscle proteins that control contraction. Such agents represent a novel approach to treating any condition in which striated muscle function is compromised, including heart failure, cardiomyopathies, skeletal myopathies and a wide range of neuromuscular conditions. Here, we review agents that modulate the mechanical function of the sarcomere, focusing on emerging compounds that target myosin or the troponin complex.
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33
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Ravenscroft G, Laing NG, Bönnemann CG. Pathophysiological concepts in the congenital myopathies: blurring the boundaries, sharpening the focus. ACTA ACUST UNITED AC 2014; 138:246-68. [PMID: 25552303 DOI: 10.1093/brain/awu368] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The congenital myopathies are a diverse group of genetic skeletal muscle diseases, which typically present at birth or in early infancy. There are multiple modes of inheritance and degrees of severity (ranging from foetal akinesia, through lethality in the newborn period to milder early and later onset cases). Classically, the congenital myopathies are defined by skeletal muscle dysfunction and a non-dystrophic muscle biopsy with the presence of one or more characteristic histological features. However, mutations in multiple different genes can cause the same pathology and mutations in the same gene can cause multiple different pathologies. This is becoming ever more apparent now that, with the increasing use of next generation sequencing, a genetic diagnosis is achieved for a greater number of patients. Thus, considerable genetic and pathological overlap is emerging, blurring the classically established boundaries. At the same time, some of the pathophysiological concepts underlying the congenital myopathies are moving into sharper focus. Here we explore whether our emerging understanding of disease pathogenesis and underlying pathophysiological mechanisms, rather than a strictly gene-centric approach, will provide grounds for a different and perhaps complementary grouping of the congenital myopathies, that at the same time could help instil the development of shared potential therapeutic approaches. Stemming from recent advances in the congenital myopathy field, five key pathophysiology themes have emerged: defects in (i) sarcolemmal and intracellular membrane remodelling and excitation-contraction coupling; (ii) mitochondrial distribution and function; (iii) myofibrillar force generation; (iv) atrophy; and (v) autophagy. Based on numerous emerging lines of evidence from recent studies in cell lines and patient tissues, mouse models and zebrafish highlighting these unifying pathophysiological themes, here we review the congenital myopathies in relation to these emerging pathophysiological concepts, highlighting both areas of overlap between established entities, as well as areas of distinction within single gene disorders.
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Affiliation(s)
- Gianina Ravenscroft
- 1 Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Nigel G Laing
- 1 Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands, Western Australia, Australia
| | - Carsten G Bönnemann
- 2 National Institute of Neurological Disorders and Stroke/NIH, Porter Neuroscience Research Centre, Bethesda, MD, USA
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34
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Marttila M, Hanif M, Lemola E, Nowak KJ, Laitila J, Grönholm M, Wallgren-Pettersson C, Pelin K. Nebulin interactions with actin and tropomyosin are altered by disease-causing mutations. Skelet Muscle 2014; 4:15. [PMID: 25110572 PMCID: PMC4126377 DOI: 10.1186/2044-5040-4-15] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 06/09/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Nemaline myopathy (NM) is a rare genetic muscle disorder, but one of the most common among the congenital myopathies. NM is caused by mutations in at least nine genes: Nebulin (NEB), α-actin (ACTA1), α-tropomyosin (TPM3), β-tropomyosin (TPM2), troponin T (TNNT1), cofilin-2 (CFL2), Kelch repeat and BTB (POZ) domain-containing 13 (KBTBD13), and Kelch-like family members 40 and 41 (KLHL40 and KLHL41). Nebulin is a giant (600 to 900 kDa) filamentous protein constituting part of the skeletal muscle thin filament. Around 90% of the primary structure of nebulin is composed of approximately 35-residue α-helical domains, which form super repeats that bind actin with high affinity. Each super repeat has been proposed to harbor one tropomyosin-binding site. METHODS We produced four wild-type (WT) nebulin super repeats (S9, S14, S18, and S22), 283 to 347 amino acids long, and five corresponding repeats with a patient mutation included: three missense mutations (p.Glu2431Lys, p.Ser6366Ile, and p.Thr7382Pro) and two in-frame deletions (p.Arg2478_Asp2512del and p.Val3924_Asn3929del). We performed F-actin and tropomyosin-binding experiments for the nebulin super repeats, using co-sedimentation and GST (glutathione-S-transferase) pull-down assays. We also used the GST pull-down assay to test the affinity of WT nebulin super repeats for WT α- and β-tropomyosin, and for β-tropomyosin with six patient mutations: p.Lys7del, p.Glu41Lys, p.Lys49del, p.Glu117Lys, p.Glu139del and p.Gln147Pro. RESULTS WT nebulin was shown to interact with actin and tropomyosin. Both the nebulin super repeats containing the p.Glu2431Lys mutation and nebulin super repeats lacking exon 55 (p.Arg2478_Asp2512del) showed weak affinity for F-actin compared with WT fragments. Super repeats containing the p.Ser6366Ile mutation showed strong affinity for actin. When tested for tropomyosin affinity, super repeats containing the p.Glu2431Lys mutation showed stronger binding than WT proteins to tropomyosin, and the super repeat containing the p.Thr7382Pro mutation showed weaker binding than WT proteins to tropomyosin. Super repeats containing the deletion p.Val3924_Asn3929del showed similar affinity for actin and tropomyosin as that seen with WT super repeats. Of the tropomyosin mutations, only p.Glu41Lys showed weaker affinity for nebulin (super repeat 18). CONCLUSIONS We demonstrate for the first time the existence of direct tropomyosin-nebulin interactions in vitro, and show that nebulin interactions with actin and tropomyosin are altered by disease-causing mutations in nebulin and tropomyosin.
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Affiliation(s)
- Minttu Marttila
- The Folkhälsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland.,Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Mubashir Hanif
- The Folkhälsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland.,Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Elina Lemola
- The Folkhälsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland.,Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Kristen J Nowak
- Molecular Neurogenetics Laboratory, Centre for Medical Research, University of Western Australia, Nedlands, Australia
| | - Jenni Laitila
- The Folkhälsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland.,Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Mikaela Grönholm
- Department of Biosciences, Division of Biochemistry and Biotechnology, University of Helsinki, Helsinki, Finland
| | - Carina Wallgren-Pettersson
- The Folkhälsan Institute of Genetics, Biomedicum Helsinki, Helsinki, Finland.,Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Katarina Pelin
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
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Abstract
PURPOSE OF REVIEW This article reviews recent advances in the understanding of nemaline myopathy, with a focus on the genetic basis of the disorder, histology, and pathogenesis. RECENT FINDINGS Pathogenic mutations have been identified in eight genes and there is evidence of further genetic heterogeneity in nemaline myopathy. Clinical presentation, histological features on skeletal muscle biopsy, and pattern of changes on muscle MRI may guide prioritization of molecular genetic testing. It is anticipated that use of new technologies such as whole exome sequencing and comparative genomic hybridization will increase the number of genes associated with nemaline myopathy and the proportion of patients in whom the genetic basis of the disorder is identified. Single fiber studies and animal models continue to add to understanding of the pathogenesis of this disorder. Current management focuses on supportive treatment; however, encouraging advances are emerging for the future. SUMMARY Recent advances in understanding of nemaline myopathy have important implications for clinical practice and for genetic diagnosis of patients with nemaline myopathy.
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Malfatti E, Lehtokari VL, Böhm J, De Winter JM, Schäffer U, Estournet B, Quijano-Roy S, Monges S, Lubieniecki F, Bellance R, Viou MT, Madelaine A, Wu B, Taratuto AL, Eymard B, Pelin K, Fardeau M, Ottenheijm CAC, Wallgren-Pettersson C, Laporte J, Romero NB. Muscle histopathology in nebulin-related nemaline myopathy: ultrastrastructural findings correlated to disease severity and genotype. Acta Neuropathol Commun 2014; 2:44. [PMID: 24725366 PMCID: PMC4234932 DOI: 10.1186/2051-5960-2-44] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 01/09/2023] Open
Abstract
Nemaline myopathy (NM) is a rare congenital myopathy characterised by hypotonia, muscle weakness, and often skeletal muscle deformities with the presence of nemaline bodies (rods) in the muscle biopsy. The nebulin (NEB) gene is the most commonly mutated and is thought to account for approximately 50% of genetically diagnosed cases of NM. We undertook a detailed muscle morphological analysis of 14 NEB-mutated NM patients with different clinical forms to define muscle pathological patterns and correlate them with clinical course and genotype. Three groups were identified according to clinical severity. Group 1 (n = 5) comprises severe/lethal NM and biopsy in the first days of life. Group 2 (n = 4) includes intermediate NM and biopsy in infancy. Group 3 (n = 5) comprises typical/mild NM and biopsy in childhood or early adult life. Biopsies underwent histoenzymological, immunohistochemical and ultrastructural analysis. Fibre type distribution patterns, rod characteristics, distribution and localization were investigated. Contractile performance was studied in muscle fibre preparations isolated from seven muscle biopsies from each of the three groups. G1 showed significant myofibrillar dissociation and smallness with scattered globular rods in one third of fibres; there was no type 1 predominance. G2 presented milder sarcomeric dissociation, dispersed or clustered nemaline bodies, and type 1 predominance/uniformity. In contrast, G3 had well-delimited clusters of subsarcolemmal elongated rods and type 1 uniformity without sarcomeric alterations. In accordance with the clinical and morphological data, functional studies revealed markedly low forces in muscle bundles from G1 and a better contractile performance in muscle bundles from biopsies of patients from G2, and G3. In conclusion NEB-mutated NM patients present a wide spectrum of morphological features. It is difficult to establish firm genotype phenotype correlation. Interestingly, there was a correlation between clinical severity on the one hand and the degree of sarcomeric dissociation and contractility efficiency on the other. By contrast the percentage of fibres occupied by rods, as well as the quantity and the sub sarcolemmal position of rods, appears to inversely correlate with severity. Based on our observations, we propose myofibrillar dissociation and changes in contractility as an important cause of muscle weakness in NEB-mutated NM patients.
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Scoto M, Cullup T, Cirak S, Yau S, Manzur AY, Feng L, Jacques TS, Anderson G, Abbs S, Sewry C, Jungbluth H, Muntoni F. Nebulin (NEB) mutations in a childhood onset distal myopathy with rods and cores uncovered by next generation sequencing. Eur J Hum Genet 2013; 21:1249-52. [PMID: 23443021 PMCID: PMC3798838 DOI: 10.1038/ejhg.2013.31] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/16/2013] [Accepted: 01/24/2013] [Indexed: 11/09/2022] Open
Abstract
Recessive nebulin (NEB) mutations are a common cause of nemaline myopathy (NM), typically characterized by generalized weakness of early-onset and nemaline rods on muscle biopsy. Exceptional adult cases with additional cores and an isolated distal weakness have been reported. The large NEB gene with 183 exons has been an obstacle for the genetic work-up. Here we report a childhood-onset case with distal weakness and a core-rod myopathy, associated with recessive NEB mutations identified by next generation sequencing (NGS). This 6-year-old boy presented with a history of gross-motor difficulties following a normal early development. He had distal leg weakness with bilateral foot drop, as well as axial muscle weakness, scoliosis and spinal rigidity; additionally he required nocturnal respiratory support. Muscle magnetic resonance (MR) imaging showed distal involvement in the medial and anterior compartment of the lower leg. A muscle biopsy featured both rods and cores. Initial targeted testing identified a heterozygous Nebulin exon 55 deletion. Further analysis using NGS revealed a frameshifting 4 bp duplication, c.24372_24375dup (P.Val8126fs), on the opposite allele. This case illustrates that NEB mutations can cause childhood onset distal NM, with additional cores on muscle biopsy and proves the diagnostic utility of NGS for myopathies, particularly when large genes are implicated.
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Affiliation(s)
| | - Thomas Cullup
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
| | - Sebahattin Cirak
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - Shu Yau
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
| | - Adnan Y Manzur
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - Lucy Feng
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
| | - Thomas S Jacques
- Neural Development Unit, UCL Institute of Child Health, London, UK
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Glenn Anderson
- Department of Histopathology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Stephen Abbs
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
| | - Caroline Sewry
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
- Centre for Inherited Neuromuscular Diseases, RJAH Orthopaedic NHS Foundation Trust, Oswestry, UK
| | - Heinz Jungbluth
- Clinical Neuroscience Division, IOP, King's College London, London, UK
- Department of Paediatric Neurology – Neuromuscular Service, Evelina Children's Hospital, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, UCL Institute of Child Health, London, UK
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38
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Abstract
Congenital myopathies are severe muscle disorders affecting adults as well as children in all populations. The diagnosis of congenital myopathies is constrained by strong clinical and genetic heterogeneity. Moreover, the majority of patients present with unspecific histological features, precluding purposive molecular diagnosis and demonstrating the need for an alternative and more efficient diagnostic approach. We used exome sequencing complemented by histological and ultrastructural analysis of muscle biopsies to identify the causative mutations in eight patients with clinically different skeletal muscle pathologies, ranging from a fatal neonatal myopathy to a mild and slowly progressive myopathy with adult onset. We identified RYR1 (ryanodine receptor) mutations in six patients and NEB (nebulin) mutations in two patients. We found novel missense and nonsense mutations, unraveled small insertions/deletions and confirmed their impact on splicing and mRNA/protein stability. Histological and ultrastructural findings of the muscle biopsies of the patients validated the exome sequencing results. We provide the evidence that an integrated strategy combining exome sequencing with clinical and histopathological investigations overcomes the limitations of the individual approaches to allow a fast and efficient diagnosis, accelerating the patient's access to a better healthcare and disease management. This is of particular interest for the diagnosis of congenital myopathies, which involve very large genes like RYR1 and NEB as well as genetic and phenotypic heterogeneity.
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Ottenheijm CAC, Buck D, de Winter JM, Ferrara C, Piroddi N, Tesi C, Jasper JR, Malik FI, Meng H, Stienen GJM, Beggs AH, Labeit S, Poggesi C, Lawlor MW, Granzier H. Deleting exon 55 from the nebulin gene induces severe muscle weakness in a mouse model for nemaline myopathy. ACTA ACUST UNITED AC 2013; 136:1718-31. [PMID: 23715096 DOI: 10.1093/brain/awt113] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nebulin--a giant sarcomeric protein--plays a pivotal role in skeletal muscle contractility by specifying thin filament length and function. Although mutations in the gene encoding nebulin (NEB) are a frequent cause of nemaline myopathy, the most common non-dystrophic congenital myopathy, the mechanisms by which mutations in NEB cause muscle weakness remain largely unknown. To better understand these mechanisms, we have generated a mouse model in which Neb exon 55 is deleted (Neb(ΔExon55)) to replicate a founder mutation seen frequently in patients with nemaline myopathy with Ashkenazi Jewish heritage. Neb(ΔExon55) mice are born close to Mendelian ratios, but show growth retardation after birth. Electron microscopy studies show nemaline bodies--a hallmark feature of nemaline myopathy--in muscle fibres from Neb(ΔExon55) mice. Western blotting studies with nebulin-specific antibodies reveal reduced nebulin levels in muscle from Neb(ΔExon55) mice, and immunofluorescence confocal microscopy studies with tropomodulin antibodies and phalloidin reveal that thin filament length is significantly reduced. In line with reduced thin filament length, the maximal force generating capacity of permeabilized muscle fibres and single myofibrils is reduced in Neb(ΔExon55) mice with a more pronounced reduction at longer sarcomere lengths. Finally, in Neb(ΔExon55) mice the regulation of contraction is impaired, as evidenced by marked changes in crossbridge cycling kinetics and by a reduction of the calcium sensitivity of force generation. A novel drug that facilitates calcium binding to the thin filament significantly augmented the calcium sensitivity of submaximal force to levels that exceed those observed in untreated control muscle. In conclusion, we have characterized the first nebulin-based nemaline myopathy model, which recapitulates important features of the phenotype observed in patients harbouring this particular mutation, and which has severe muscle weakness caused by thin filament dysfunction.
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Affiliation(s)
- Coen A C Ottenheijm
- Department of Physiology, VU University Medical Centre, Amsterdam, The Netherlands
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40
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Gineste C, Le Fur Y, Vilmen C, Le Troter A, Pecchi E, Cozzone PJ, Hardeman EC, Bendahan D, Gondin J. Combined MRI and ³¹P-MRS investigations of the ACTA1(H40Y) mouse model of nemaline myopathy show impaired muscle function and altered energy metabolism. PLoS One 2013; 8:e61517. [PMID: 23613869 PMCID: PMC3629063 DOI: 10.1371/journal.pone.0061517] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 03/11/2013] [Indexed: 11/19/2022] Open
Abstract
Nemaline myopathy (NM) is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. Mutations in the skeletal muscle α-actin gene (ACTA1) account for ∼25% of all NM cases and are the most frequent cause of severe forms of NM. So far, the mechanisms underlying muscle weakness in NM patients remain unclear. Additionally, recent Magnetic Resonance Imaging (MRI) studies reported a progressive fatty infiltration of skeletal muscle with a specific muscle involvement in patients with ACTA1 mutations. We investigated strictly noninvasively the gastrocnemius muscle function of a mouse model carrying a mutation in the ACTA1 gene (H40Y). Skeletal muscle anatomy (hindlimb muscles and fat volumes) and energy metabolism were studied using MRI and 31Phosphorus magnetic resonance spectroscopy. Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (from 1–150 Hz) and a fatigue protocol (80 stimuli at 40 Hz). H40Y mice showed a reduction of both absolute (−40%) and specific (−25%) maximal force production as compared to controls. Interestingly, muscle weakness was associated with an improved resistance to fatigue (+40%) and an increased energy cost. On the contrary, the force frequency relationship was not modified in H40Y mice and the extent of fatty infiltration was minor and not different from the WT group. We concluded that the H40Y mouse model does not reproduce human MRI findings but shows a severe muscle weakness which might be related to an alteration of intrinsic muscular properties. The increased energy cost in H40Y mice might be related to either an impaired mitochondrial function or an alteration at the cross-bridges level. Overall, we provided a unique set of anatomic, metabolic and functional biomarkers that might be relevant for monitoring the progression of NM disease but also for assessing the efficacy of potential therapeutic interventions at a preclinical level.
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Affiliation(s)
- Charlotte Gineste
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Yann Le Fur
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Christophe Vilmen
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Arnaud Le Troter
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Emilie Pecchi
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Patrick J. Cozzone
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Edna C. Hardeman
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - David Bendahan
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
| | - Julien Gondin
- Aix-Marseille Université, Centre National de la Recherche Scientifique (CNRS), Centre de Résonance Magnétique Biologique et Médicale (CRMBM) Unité Mixte de Recherche (UMR), Marseille, France
- * E-mail:
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41
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de Winter JM, Buck D, Hidalgo C, Jasper JR, Malik FI, Clarke NF, Stienen GJM, Lawlor MW, Beggs AH, Ottenheijm CAC, Granzier H. Troponin activator augments muscle force in nemaline myopathy patients with nebulin mutations. J Med Genet 2013; 50:383-92. [PMID: 23572184 PMCID: PMC3865762 DOI: 10.1136/jmedgenet-2012-101470] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background Nemaline myopathy—the most common non-dystrophic congenital myopathy—is caused by mutations in thin filament genes, of which the nebulin gene is the most frequently affected one. The nebulin gene codes for the giant sarcomeric protein nebulin, which plays a crucial role in skeletal muscle contractile performance. Muscle weakness is a hallmark feature of nemaline myopathy patients with nebulin mutations, and is caused by changes in contractile protein function, including a lower calcium-sensitivity of force generation. To date no therapy exists to treat muscle weakness in nemaline myopathy. Here, we studied the ability of the novel fast skeletal muscle troponin activator, CK-2066260, to augment force generation at submaximal calcium levels in muscle cells from nemaline myopathy patients with nebulin mutations. Methods Contractile protein function was determined in permeabilised muscle cells isolated from frozen patient biopsies. The effect of 5 µM CK-2066260 on force production was assessed. Results Nebulin protein concentrations were severely reduced in muscle cells from these patients compared to controls, while myofibrillar ultrastructure was largely preserved. Both maximal active tension and the calcium-sensitivity of force generation were lower in patients compared to controls. Importantly, CK-2066260 greatly increased the calcium-sensitivity of force generation—without affecting the cooperativity of activation—in patients to levels that exceed those observed in untreated control muscle. Conclusions Fast skeletal troponin activation is a therapeutic mechanism to augment contractile protein function in nemaline myopathy patients with nebulin mutations and with other neuromuscular diseases.
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Affiliation(s)
- Josine Marieke de Winter
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
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Lee EJ, De Winter JM, Buck D, Jasper JR, Malik FI, Labeit S, Ottenheijm CA, Granzier H. Fast skeletal muscle troponin activation increases force of mouse fast skeletal muscle and ameliorates weakness due to nebulin-deficiency. PLoS One 2013; 8:e55861. [PMID: 23437068 PMCID: PMC3577798 DOI: 10.1371/journal.pone.0055861] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022] Open
Abstract
The effect of the fast skeletal muscle troponin activator, CK-2066260, on calcium-induced force development was studied in skinned fast skeletal muscle fibers from wildtype (WT) and nebulin deficient (NEB KO) mice. Nebulin is a sarcomeric protein that when absent (NEB KO mouse) or present at low levels (nemaline myopathy (NM) patients with NEB mutations) causes muscle weakness. We studied the effect of fast skeletal troponin activation on WT muscle and tested whether it might be a therapeutic mechanism to increase muscle strength in nebulin deficient muscle. We measured tension-pCa relations with and without added CK-2066260. Maximal active tension in NEB KO tibialis cranialis fibers in the absence of CK-2066260 was ∼60% less than in WT fibers, consistent with earlier work. CK-2066260 shifted the tension-calcium relationship leftwards, with the largest relative increase (up to 8-fold) at low to intermediate calcium levels. This was a general effect that was present in both WT and NEB KO fiber bundles. At pCa levels above ∼6.0 (i.e., calcium concentrations <1 µM), CK-2066260 increased tension of NEB KO fibers to beyond that of WT fibers. Crossbridge cycling kinetics were studied by measuring k(tr) (rate constant of force redevelopment following a rapid shortening/restretch). CK-2066260 greatly increased k(tr) at submaximal activation levels in both WT and NEB KO fiber bundles. We also studied the sarcomere length (SL) dependence of the CK-2066260 effect (SL 2.1 µm and 2.6 µm) and found that in the NEB KO fibers, CK-2066260 had a larger effect on calcium sensitivity at the long SL. We conclude that fast skeletal muscle troponin activation increases force at submaximal activation in both wildtype and NEB KO fiber bundles and, importantly, that this troponin activation is a potential therapeutic mechanism for increasing force in NM and other skeletal muscle diseases with loss of muscle strength.
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Affiliation(s)
- Eun-Jeong Lee
- Department of Physiology, University of Arizona, Tucson, Arizona, United States of America
| | - Josine M. De Winter
- Institute for Cardiovascular Research, Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Danielle Buck
- Department of Physiology, University of Arizona, Tucson, Arizona, United States of America
| | - Jeffrey R. Jasper
- Research & Early Development, Cytokinetics, Inc., South San Francisco, California, United States of America
| | - Fady I. Malik
- Research & Early Development, Cytokinetics, Inc., South San Francisco, California, United States of America
| | - Siegfried Labeit
- Department of Integrative Pathophysiology, Universitätsmedizin Mannheim, University of Heidelberg, Mannheim, Germany
| | - Coen A. Ottenheijm
- Department of Physiology, University of Arizona, Tucson, Arizona, United States of America
- Institute for Cardiovascular Research, Department of Physiology, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Henk Granzier
- Department of Physiology, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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43
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Gineste C, De Winter JM, Kohl C, Witt CC, Giannesini B, Brohm K, Le Fur Y, Gretz N, Vilmen C, Pecchi E, Jubeau M, Cozzone PJ, Stienen GJM, Granzier H, Labeit S, Ottenheijm CAC, Bendahan D, Gondin J. In vivo and in vitro investigations of heterozygous nebulin knock-out mice disclose a mild skeletal muscle phenotype. Neuromuscul Disord 2013; 23:357-69. [PMID: 23375831 DOI: 10.1016/j.nmd.2012.12.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 12/07/2012] [Accepted: 12/29/2012] [Indexed: 01/30/2023]
Abstract
Nemaline myopathy is the most common congenital skeletal muscle disease, and mutations in the nebulin gene account for 50% of all cases. Recent studies suggest that the disease severity might be related to the nebulin expression levels. Considering that mutations in the nebulin gene are typically recessive, one would expect that a single functional nebulin allele would maintain nebulin protein expression which would result in preserved skeletal muscle function. We investigated skeletal muscle function of heterozygous nebulin knock-out (i.e., nebulin(+/-)) mice using a multidisciplinary approach including protein and gene expression analysis and combined in vivo and in vitro force measurements. Skeletal muscle anatomy and energy metabolism were studied strictly non-invasively using magnetic resonance imaging and 31P-magnetic resonance spectroscopy. Maximal force production was reduced by around 16% in isolated muscle of nebulin(+/-) mice while in vivo force generating capacity was preserved. Muscle weakness was associated with a shift toward a slower proteomic phenotype, but was not related to nebulin protein deficiency or to an impaired energy metabolism. Further studies would be warranted in order to determine the mechanisms leading to a mild skeletal muscle phenotype resulting from the expression of a single nebulin allele.
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Affiliation(s)
- C Gineste
- Aix-Marseille Université, CRMBM, 13005 Marseille, France
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44
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Dieterich K, Quijano-Roy S, Monnier N, Zhou J, Fauré J, Smirnow DA, Carlier R, Laroche C, Marcorelles P, Mercier S, Mégarbané A, Odent S, Romero N, Sternberg D, Marty I, Estournet B, Jouk PS, Melki J, Lunardi J. The neuronal endopeptidase ECEL1 is associated with a distinct form of recessive distal arthrogryposis. Hum Mol Genet 2012; 22:1483-92. [PMID: 23236030 DOI: 10.1093/hmg/dds514] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Distal arthrogryposis (DA) is a heterogeneous subgroup of arthrogryposis multiplex congenita (AMC), a large family of disorders characterized by multiple congenital joint limitations due to reduced fetal movements. DA is mainly characterized by contractures afflicting especially the distal extremities without overt muscular or neurological signs. Although a limited number of genes mostly implicated in the contractile apparatus have been identified in DA, most patients failed to show mutations in currently known genes. Using a pangenomic approach, we demonstrated linkage of DA to chromosome 2q37 in two consanguineous families and the endothelin-converting enzyme like 1 (ECEL1) gene present in this region was associated with DA. Screening of a panel of 20 families with non-specific DA identified seven homozygous or compound heterozygous mutations of ECEL1 in a total of six families. Mutations resulted mostly in the absence of protein. ECEL1 is a neuronal endopeptidase predominantly expressed in the central nervous system and brain structures during fetal life in mice and human. ECEL1 plays a major role in intramuscular axonal branching of motor neurons in skeletal muscle during embryogenesis. A detailed review of clinical findings of DA patients with ECEL1 mutations revealed a homogeneous and recognizable phenotype characterized by limited knee flexion, flexed third to fifth fingers and severe muscle atrophy predominant on lower limbs and tongue that suggested a common pathogenic mechanism. We described a new and homogenous phenotype of DA associated with ECEL1 that resulted in symptoms involving rather the peripheral than the central nervous system and suggesting a developmental dysfunction.
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Affiliation(s)
- Klaus Dieterich
- Inserm U836, Grenoble Institut des Neurosciences, Equipe Muscle et Pathologie, Grenoble, France
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Nance JR, Dowling JJ, Gibbs EM, Bönnemann CG. Congenital myopathies: an update. Curr Neurol Neurosci Rep 2012; 12:165-74. [PMID: 22392505 DOI: 10.1007/s11910-012-0255-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Congenital myopathy is a clinicopathological concept of characteristic histopathological findings on muscle biopsy in a patient with early-onset weakness. Three main categories are recognized within the classical congenital myopathies: nemaline myopathy, core myopathy, and centronuclear myopathy. Recent evidence of overlapping clinical and histological features between the classical forms and their different genetic entities suggests that there may be shared pathomechanisms between the congenital myopathies. Animal models, especially mouse and zebrafish, have been especially helpful in elucidating such pathomechanisms associated with the congenital myopathies and provide models in which future therapies can be investigated.
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Affiliation(s)
- Jessica R Nance
- Department of Neurology, Children's National Medical Center, Washington, DC 20010, USA
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