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Fu L, Zou Y, Yu B, Hong D, Guan T, Hu J, Xu Y, Wu Y, Kou J, Lv Y. Background and roles: myosin in autoimmune diseases. Front Cell Dev Biol 2023; 11:1220672. [PMID: 37691828 PMCID: PMC10484797 DOI: 10.3389/fcell.2023.1220672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 08/09/2023] [Indexed: 09/12/2023] Open
Abstract
The myosin superfamily is a group of molecular motors. Autoimmune diseases are characterized by dysregulation or deficiency of the immune tolerance mechanism, resulting in an immune response to the human body itself. The link between myosin and autoimmune diseases is much more complex than scientists had hoped. Myosin itself immunization can induce experimental autoimmune diseases of animals, and myosins were abnormally expressed in a number of autoimmune diseases. Additionally, myosin takes part in the pathological process of multiple sclerosis, Alzheimer's disease, Parkinson's disease, autoimmune myocarditis, myositis, hemopathy, inclusion body diseases, etc. However, research on myosin and its involvement in the occurrence and development of diseases is still in its infancy, and the underlying pathological mechanisms are not well understood. We can reasonably predict that myosin might play a role in new treatments of autoimmune diseases.
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Affiliation(s)
- Longsheng Fu
- Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Yonghui Zou
- Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Boyang Yu
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, Jiangxi, China
| | - Daojun Hong
- Department of Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Teng Guan
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, MB, Canada
| | - Jinfang Hu
- Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Yi Xu
- Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Yaoqi Wu
- Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Junping Kou
- Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing, Jiangxi, China
| | - Yanni Lv
- Department of Pharmacy, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China
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Sato K, Miyauchi Y, Xu X, Kon R, Ikarashi N, Chiba Y, Hosoe T, Sakai H. Platinum-based anticancer drugs-induced downregulation of myosin heavy chain isoforms in skeletal muscle of mouse. J Pharmacol Sci 2023; 152:167-177. [PMID: 37257944 DOI: 10.1016/j.jphs.2023.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/19/2023] [Accepted: 04/24/2023] [Indexed: 06/02/2023] Open
Abstract
Cisplatin, a platinum-based anticancer drug used frequently in cancer treatment, causes skeletal muscle atrophy. It was predicted that the proteolytic pathway is enhanced as the mechanism of this atrophy. Therefore, we investigated whether a platinum-based anticancer drug affects the expression of the major proteins of skeletal muscle, myosin heavy chain (MyHC). Mice were injected with cisplatin or oxaliplatin for four consecutive days. C2C12 myotubes were treated using cisplatin and oxaliplatin. Administration of platinum-based anticancer drug reduced quadriceps mass and muscle strength compared to the control group. Protein levels of all MyHC isoforms were reduced in the platinum-based anticancer drug groups. However, only Myh2 (MyHC-IIa) gene expression in skeletal muscle of mice treated with platinum-based anticancer drugs was found to be reduced. Treatment of C2C12 myotubes with platinum-based anticancer drugs reduced the protein levels of all MyHCs, and treatment with the proteasome inhibitor MG-132 restored this reduction. The expression of Mef2c, which was predicted to act upstream of Myh2, was reduced in the skeletal muscle of mice treated systemically with platinum-based anticancer drug. Degradation of skeletal muscle MyHCs by proteasomes may be a factor that plays an important role in muscle mass loss in platinum-based anticancer drug-induced muscle atrophy.
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Affiliation(s)
- Ken Sato
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Yu Miyauchi
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Xinran Xu
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Risako Kon
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Nobutomo Ikarashi
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Yoshihiko Chiba
- Department of Physiology and Molecular Sciences, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Tomoo Hosoe
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan; Department of Bioregulatory Science, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan
| | - Hiroyasu Sakai
- Department of Biomolecular Pharmacology, School of Pharmacy, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 1428501, Japan.
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Sonne A, Peverelli L, Hernandez-Lain A, Domínguez-González C, Andersen JL, Milone M, Beggs AH, Ochala J. Myosin post-translational modifications and function in the presence of myopathy-linked truncating MYH2 mutations. Am J Physiol Cell Physiol 2023; 324:C769-C776. [PMID: 36745529 DOI: 10.1152/ajpcell.00002.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Congenital myopathies are a vast group of genetic muscle diseases. Among the causes are mutations in the MYH2 gene resulting in truncated type IIa myosin heavy chains (MyHCs). The precise cellular and molecular mechanisms by which these mutations induce skeletal muscle symptoms remain obscure. Hence, in the present study, we aimed to explore whether such genetic defects would alter the presence as well as the post-translational modifications of MyHCs and the functionality of myosin molecules. For this, we dissected muscle fibers from four myopathic patients with MYH2 truncating mutations and from five human healthy controls. We then assessed 1) MyHCs presence/post-translational modifications using LC/MS; 2) relaxed myosin conformation and concomitant ATP consumption with a loaded Mant-ATP chase setup; 3) myosin activation with an unloaded in vitro motility assay; and 4) cellular force production with a myofiber mechanical setup. Interestingly, the type IIa MyHC with one additional acetylated lysine (Lys35-Ac) was present in the patients. This was accompanied by 1) a higher ATP demand of myosin heads in the disordered-relaxed conformation; 2) faster actomyosin kinetics; and 3) reduced muscle fiber force. Overall, our findings indicate that MYH2 truncating mutations impact myosin presence/functionality in human adult mature myofibers by disrupting the ATPase activity and actomyosin complex. These are likely important molecular pathological disturbances leading to the myopathic phenotype in patients.
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Affiliation(s)
- Alexander Sonne
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lorenzo Peverelli
- Neuromuscular and Rare Diseases Unit, Department of Neuroscience, Fondazione, IRCCS Ca' Granda Ospedale Maggiore, Policlinico, Milan, Italy
| | - Aurelio Hernandez-Lain
- Neuropathology Unit, Department of Pathology, 12 de Octubre University Hospital, Madrid, Spain.,imas12 Research Institute, Rare Diseases Network Biomedical Research Center (CIBERER), 12 de Octubre University Hospital, Madrid, Spain
| | - Cristina Domínguez-González
- imas12 Research Institute, Rare Diseases Network Biomedical Research Center (CIBERER), 12 de Octubre University Hospital, Madrid, Spain.,Neuromuscular Unit, Department of Neurology, 12 de Octubre University Hospital, Madrid, Spain
| | - Jesper L Andersen
- Department of Orthopaedic Surgery, Institute of Sports Medicine Copenhagen, University Copenhagen Hospital-Bispebjerg and Frederiksberg, Copenhagen, Denmark.,Center for Healthy Aging, Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Margherita Milone
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, United States
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Julien Ochala
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Centre for Human and Applied Physiological Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
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Kuntawala DH, Martins F, Vitorino R, Rebelo S. Automatic Text-Mining Approach to Identify Molecular Target Candidates Associated with Metabolic Processes for Myotonic Dystrophy Type 1. Int J Environ Res Public Health 2023; 20:2283. [PMID: 36767649 PMCID: PMC9915907 DOI: 10.3390/ijerph20032283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/20/2023] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant hereditary disease caused by abnormal expansion of unstable CTG repeats in the 3' untranslated region of the myotonic dystrophy protein kinase (DMPK) gene. This disease mainly affects skeletal muscle, resulting in myotonia, progressive distal muscle weakness, and atrophy, but also affects other tissues and systems, such as the heart and central nervous system. Despite some studies reporting therapeutic strategies for DM1, many issues remain unsolved, such as the contribution of metabolic and mitochondrial dysfunctions to DM1 pathogenesis. Therefore, it is crucial to identify molecular target candidates associated with metabolic processes for DM1. In this study, resorting to a bibliometric analysis, articles combining DM1, and metabolic/metabolism terms were identified and further analyzed using an unbiased strategy of automatic text mining with VOSviewer software. A list of candidate molecular targets for DM1 associated with metabolic/metabolism was generated and compared with genes previously associated with DM1 in the DisGeNET database. Furthermore, g:Profiler was used to perform a functional enrichment analysis using the Gene Ontology (GO) and REAC databases. Enriched signaling pathways were identified using integrated bioinformatics enrichment analyses. The results revealed that only 15 of the genes identified in the bibliometric analysis were previously associated with DM1 in the DisGeNET database. Of note, we identified 71 genes not previously associated with DM1, which are of particular interest and should be further explored. The functional enrichment analysis of these genes revealed that regulation of cellular metabolic and metabolic processes were the most associated biological processes. Additionally, a number of signaling pathways were found to be enriched, e.g., signaling by receptor tyrosine kinases, signaling by NRTK1 (TRKA), TRKA activation by NGF, PI3K-AKT activation, prolonged ERK activation events, and axon guidance. Overall, several valuable target candidates related to metabolic processes for DM1 were identified, such as NGF, NTRK1, RhoA, ROCK1, ROCK2, DAG, ACTA, ID1, ID2 MYOD, and MYOG. Therefore, our study strengthens the hypothesis that metabolic dysfunctions contribute to DM1 pathogenesis, and the exploitation of metabolic dysfunction targets is crucial for the development of future therapeutic interventions for DM1.
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Baskar D, Vengalil S, Nashi S, Bardhan M, Srivastava K, Sanka SB, Polavarapu K, Menon D, Preethish-Kumar V, Padmanabha H, Arunachal G, Nalini A. MYH2-related Myopathy: Expanding the Clinical Spectrum of Chronic Progressive External Ophthalmoplegia (CPEO). J Neuromuscul Dis 2023; 10:727-730. [PMID: 37154181 PMCID: PMC10357141 DOI: 10.3233/jnd-230017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2023] [Indexed: 05/10/2023]
Abstract
Chronic progressive external ophthalmoplegia (CPEO) is symptom complex with progressive ptosis and restricted ocular motility without diplopia. MYH2 myopathy is rare disorder presenting with CPEO and muscle weakness. We report two Indian patients of MYH2 myopathy with unique features. Patient-1 presented with early adult-onset esophageal reflux followed by, proximal lower limb weakness, proptosis, CPEO without ptosis. He had elevated creatine kinase along with characteristic muscle MRI findings of prominent semitendinosus and medial gastrocnemius involvement. Patient -2 presented with early adult onset CPEO without limb weakness. His creatine kinase was normal. Both the patients had novel MYH2 mutations: a homozygous 5'splice variation in intron 4 (c.348 + 2dup) in patient 1 and homozygous single base pair deletion in exon 32 (p. Ala1480ProfsTer11) in patient 2. Unique features noted include adult onset, isolated CPEO, proptosis, esophageal reflux disease and absence of skeletal abnormalities. MYH2 myopathy has to be considered in adult patients with CPEO.
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Affiliation(s)
- Dipti Baskar
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Seena Vengalil
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Saraswati Nashi
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Mainak Bardhan
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Kosha Srivastava
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Sai Bhargava Sanka
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Kiran Polavarapu
- Department of Medicine, Children’s Hospitalof Eastern Ontario Research Institute, University of Ottawa and Division of Neurology, The Ottawa Hospital, Ottawa, Canada
| | - Deepak Menon
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | | | - Hansashree Padmanabha
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, Karnataka, India
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Hitachi K, Kiyofuji Y, Yamaguchi H, Nakatani M, Inui M, Tsuchida K. Simultaneous loss of skeletal muscle myosin heavy chain IIx and IIb causes severe skeletal muscle hypoplasia in postnatal mice. FASEB J 2023; 37:e22692. [PMID: 36515178 DOI: 10.1096/fj.202200581r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 11/09/2022] [Accepted: 11/22/2022] [Indexed: 12/15/2022]
Abstract
The skeletal muscle myosin heavy chain (MyHC) is a fundamental component of the sarcomere structure and muscle contraction. Two of the three adult fast MyHCs, MyHC-IIx and MyHC-IIb, are encoded by Myh1 and Myh4, respectively. However, skeletal muscle disorders have not yet been linked to these genes in humans. MyHC-IIb is barely detectable in human skeletal muscles. Thus, to characterize the molecular function of skeletal muscle MyHCs in humans, investigation of the effect of simultaneous loss of MyHC-IIb and other MyHCs on skeletal muscle in mice is essential. Here, we generated double knockout (dKO) mice with simultaneous loss of adult fast MyHCs by introducing nonsense frameshift mutations into the Myh1 and Myh4 genes. The dKO mice appeared normal after birth and until 2 weeks of age but showed severe skeletal muscle hypoplasia after 2 weeks. In 3-week-old dKO mice, increased expression of other skeletal muscle MyHCs, such as MyHC-I, MyHC-IIa, MyHC-neo, and MyHC-emb, was observed. However, these expressions were not sufficient to compensate for the loss of MyHC-IIb and MyHC-IIx. Moreover, the aberrant sarcomere structure with altered expression of sarcomere components was observed in dKO mice. Our findings imply that the simultaneous loss of MyHC-IIb and MyHC-IIx is substantially detrimental to postnatal skeletal muscle function and will contribute to elucidating the molecular mechanisms of skeletal muscle wasting disorders caused by the loss of skeletal muscle MyHCs.
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Affiliation(s)
- Keisuke Hitachi
- Division for Therapies against Intractable Diseases, Institute for Comprehensive Medical Science (ICMS), Fujita Health University, Toyoake, Japan
| | - Yuri Kiyofuji
- Division for Therapies against Intractable Diseases, Institute for Comprehensive Medical Science (ICMS), Fujita Health University, Toyoake, Japan
| | - Hisateru Yamaguchi
- School of Nursing and Medical Care, Yokkaichi Nursing and Medical Care University, Yokkaichi, Japan
| | - Masashi Nakatani
- Faculty of Rehabilitation and Care, Seijoh University, Tokai, Japan
| | - Masafumi Inui
- Laboratory of Animal Regeneration Systemology, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Japan
| | - Kunihiro Tsuchida
- Division for Therapies against Intractable Diseases, Institute for Comprehensive Medical Science (ICMS), Fujita Health University, Toyoake, Japan
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Hedberg-Oldfors C, Elíasdóttir Ó, Geijer M, Lindberg C, Oldfors A. Dominantly inherited myosin IIa myopathy caused by aberrant splicing of MYH2. BMC Neurol 2022; 22:428. [PMCID: PMC9664609 DOI: 10.1186/s12883-022-02935-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/25/2022] [Indexed: 11/16/2022] Open
Abstract
Abstract
Background
Myosin heavy chain (MyHC) isoforms define the three major muscle fiber types in human extremity muscles. Slow beta/cardiac MyHC (MYH7) is expressed in type 1 muscle fibers. MyHC IIa (MYH2) and MyHC IIx (MYH1) are expressed in type 2A and 2B fibers, respectively. Whereas recessive MyHC IIa myopathy has been described in many cases, myopathy caused by dominant MYH2 variants is rare and has been described with clinical manifestations and muscle pathology in only one family and two sporadic cases.
Methods
We investigated three patients from one family with a dominantly inherited myopathy by clinical investigation, whole-genome sequencing, muscle biopsy, and magnetic resonance imaging (MRI).
Results
Three siblings, one woman and two men now 54, 56 and 66 years old, had experienced muscle weakness initially affecting the lower limbs from young adulthood. They have now generalized proximal muscle weakness affecting ambulation, but no ophthalmoplegia. Whole-genome sequencing identified a heterozygous MYH2 variant, segregating with the disease in the three affected individuals: c.5673 + 1G > C. Analysis of cDNA confirmed the predicted splicing defect with skipping of exon 39 and loss of residues 1860–1891 in the distal tail of the MyHC IIa, largely overlapping with the filament assembly region (aa1877–1905). Muscle biopsy in two of the affected individuals showed prominent type 1 muscle fiber predominance with only a few very small, scattered type 2A fibers and no type 2B fibers. The small type 2A fibers were frequently hybrid fibers with either slow MyHC or embryonic MyHC expression. The type 1 fibers showed variation in fiber size, internal nuclei and some structural alterations. There was fatty infiltration, which was also demonstrated by MRI.
Conclusion
Dominantly inherited MyHC IIa myopathy due to a splice defect causing loss of amino acids 1860–1891 in the distal tail of the MyHC IIa protein including part of the assembly competence domain. The myopathy is manifesting with slowly progressive muscle weakness without overt ophthalmoplegia and markedly reduced number and size of type 2 fibers.
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Oatmen K, Camelo-Piragua S, Zaghloul N. Novel mutation in the MYH2 gene in a symptomatic neonate with a hereditary myosin myopathy. J Neonatal Perinatal Med 2021; 15:63-68. [PMID: 34459418 DOI: 10.3233/npm-210780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Hereditary myosin myopathies are muscle disorders caused by mutations in myosin heavy chain genes. The MYH2 gene encodes the fast 2A skeletal muscle isoform, and mutations manifest as joint contractures, muscle weakness, and external ophthalmoplegia. Muscle biopsy shows decreased type 2A fibers, and vacuoles are sometimes present in adults with progressive disease. PRESENTATION OF CASE This case describes a full term baby boy with hypotonia, dysmorphic features, dysphagia, and aspiration. Whole genome sequencing detected a novel heterozygous variant in the MYH2 gene. Muscle biopsy showed decreased type 2A fibers and vacuoles in myofibers. DISCUSSION Hypotonia and dysphagia are common in infants with a MYH2 myopathy. However, dysmorphic features and vacuoles on biopsy have not previous been described in infants with MYH2 myopathies. CONCLUSION This case reports an unusual phenotype of a rare neonatal-onset congenital myopathy associated with a novel heterozygous variant in MYH2.
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Affiliation(s)
- K Oatmen
- Department of Pediatrics, University of Arizona, Tucson, AZ, USA
| | - S Camelo-Piragua
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - N Zaghloul
- Department of Pediatrics, Division of Neonatology, University of Arizona, Tucson, AZ, USA
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Madigan NN, Polzin MJ, Cui G, Liewluck T, Alsharabati MH, Klein CJ, Windebank AJ, Mer G, Milone M. Filamentous tangles with nemaline rods in MYH2 myopathy: a novel phenotype. Acta Neuropathol Commun 2021; 9:79. [PMID: 33926564 PMCID: PMC8082902 DOI: 10.1186/s40478-021-01168-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 03/21/2021] [Indexed: 11/30/2022] Open
Abstract
The MYH2 gene encodes the skeletal muscle myosin heavy chain IIA (MyHC-IIA) isoform, which is expressed in the fast twitch type 2A fibers. Autosomal dominant or recessive pathogenic variants in MYH2 lead to congenital myopathy clinically featured by ophthalmoparesis and predominantly proximal weakness. MYH2-myopathy is pathologically characterized by loss and atrophy of type 2A fibers. Additional myopathological abnormalities have included rimmed vacuoles containing small p62 positive inclusions, 15–20 nm tubulofilaments, minicores and dystrophic changes. We report an adult patient with late-pediatric onset MYH2-myopathy caused by two heterozygous pathogenic variants: c.3331C>T, p.Gln1111* predicted to result in truncation of the proximal tail region of MyHC-IIA, and c.1546T>G, p.Phe516Val, affecting a highly conserved amino acid within the highly conserved catalytic motor head relay loop. This missense variant is predicted to result in a less compact loop domain and in turn could affect the protein affinity state. The patient’s genotype is accompanied by a novel myopathological phenotype characterized by centralized large myofilamentous tangles associated with clusters of nemaline rods, and ring fibers, in addition to the previously reported rimmed vacuoles, paucity and atrophy of type 2A fibers. Electron microscopy demonstrated wide areas of disorganized myofibrils which were oriented in various planes of direction and entrapped multiple nemaline rods, as corresponding to the large tangles with rods seen on light microscopy. Nemaline rods were rarely observed also in nuclei. We speculate that the mutated MyHC-IIA may influence myofibril disorganization. While nemaline rods have been described in myopathies caused by pathogenic variants in genes encoding several sarcomeric proteins, to our knowledge, nemaline rods have not been previously described in MYH2-myopathy.
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Telese R, Pagliarani S, Lerario A, Ciscato P, Fagiolari G, Cassandrini D, Grimoldi N, Conte G, Cinnante C, Santorelli FM, Comi GP, Sciacco M, Peverelli L. MYH2 myopathy, a new case expands the clinical and pathological spectrum of the recessive form. Mol Genet Genomic Med 2020; 8:e1320. [PMID: 32578970 PMCID: PMC7507101 DOI: 10.1002/mgg3.1320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 12/10/2019] [Accepted: 04/28/2020] [Indexed: 11/18/2022] Open
Abstract
Background Hereditary myosin myopathies are a group of rare muscle disorders, caused by mutations in genes encoding for skeletal myosin heavy chains (MyHCs). MyHCIIa is encoded by MYH2 and is expressed in fast type 2A and 2B muscle fibers. MYH2 mutations are responsible for an autosomal dominant (AD) progressive myopathy, characterized by the presence of rimmed vacuoles and by a reduction in the number and size of type 2A fibers, and a recessive early onset myopathy characterized by complete loss of type 2A fibers. Recently, a patient with a homozygous mutation but presenting a dominant phenotype has been reported. Methods The patient was examined thoroughly and two muscle biopsies were performed through the years. NGS followed by confirmation in Sanger sequencing was used to identify the genetic cause. Results We describe the second case presenting with late‐onset ophthalmoparesis, ptosis, diffuse muscle weakness, and histopathological features typical for AD forms but with a recessive MYH2 genotype. Conclusion This report contributes to expand the clinical and genetic spectrum of MYH2 myopathies and to increase the awareness of these very rare diseases.
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Affiliation(s)
- Roberta Telese
- Department of Neurosciences, Imaging and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Serena Pagliarani
- Dino Ferrari Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Alberto Lerario
- Neuromuscular and Rare diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Patrizia Ciscato
- Neuromuscular and Rare diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Gigliola Fagiolari
- Neuromuscular and Rare diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Nadia Grimoldi
- University of Milan, Neurosurgey Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giorgio Conte
- Neuroradiology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Claudia Cinnante
- Neuroradiology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | | | - Giacomo P Comi
- Dino Ferrari Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Monica Sciacco
- Neuromuscular and Rare diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Lorenzo Peverelli
- Neuromuscular and Rare diseases Unit, Department of Neuroscience, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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