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Seifert BA, Reddi HV, Kang BE, Bean LJH, Shealy A, Rose NC. Myotonic dystrophy type 1 testing, 2024 revision: A technical standard of the American College of Medical Genetics and Genomics (ACMG). Genet Med 2024:101145. [PMID: 38836869 DOI: 10.1016/j.gim.2024.101145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 04/11/2024] [Indexed: 06/06/2024] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a form of muscular dystrophy causing progressive muscle loss and weakness. Although clinical features can manifest at any age, it is the most common form of muscular dystrophy with onset in adulthood. DM1 is an autosomal dominant condition, resulting from an unstable CTG expansion in the 3'-untranslated region of the myotonic dystrophy protein kinase (DMPK) gene. The age of onset and the severity of the phenotype are roughly correlated with the size of the CTG expansion. Multiple methodologies can be used to diagnose affected individuals with DM1, including polymerase chain reaction, Southern blot, and triplet repeat-primed polymerase chain reaction. Recently, triplet repeat interruptions have been described, which may affect clinical outcomes of a fully-variable allele in DMPK. This document supersedes the Technical Standards and Guidelines for Myotonic Dystrophy originally published in 2009 and reaffirmed in 2015. It is designed for genetic testing professionals who are already familiar with the disease and the methods of analysis.
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Affiliation(s)
- Bryce A Seifert
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Honey V Reddi
- Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, Milwaukee, WI
| | - Benjamin E Kang
- Department of Pathology and Pediatrics, University of Michigan Medical School, Ann Arbor, MI; Vanderbilt University Medical Center, Nashville, TN
| | | | - Amy Shealy
- Cleveland Clinic Center for Personalized Genetic Healthcare, Cleveland, OH
| | - Nancy C Rose
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Utah, Salt Lake City, UT
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2
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Yoshizumi K, Nishi M, Igeta M, Nakamori M, Inoue K, Matsumura T, Fujimura H, Jinnai K, Kimura T. Analysis of splicing abnormalities in the white matter of myotonic dystrophy type 1 brain using RNA sequencing. Neurosci Res 2024; 200:48-56. [PMID: 37806497 DOI: 10.1016/j.neures.2023.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 10/03/2023] [Accepted: 10/05/2023] [Indexed: 10/10/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder caused by the genomic expansion of CTG repeats, in which RNA-binding proteins, such as muscleblind-like protein, are sequestered in the nucleus, and abnormal splicing is observed in various genes. Although abnormal splicing occurs in the brains of patients with DM1, its relation to central nervous system symptoms is unknown. Several imaging studies have indicated substantial white matter defects in patients with DM1. Here, we performed RNA sequencing and analysis of CTG repeat lengths in the frontal lobe of patients with DM1, separating the gray matter and white matter, to investigate splicing abnormalities in the DM1 brain, especially in the white matter. Several genes showed similar levels of splicing abnormalities in both gray and white matter, with an observable trend toward an increased number of repeats in the gray matter. These findings suggest that white matter defects in DM1 stem from aberrant RNA splicing in both gray and white matter. Notably, several of the genes displaying abnormal splicing are recognized as being dominantly expressed in astrocytes and oligodendrocytes, leading us to hypothesize that splicing defects in the white matter may be attributed to abnormal RNA splicing in glial cells.
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Affiliation(s)
- Kazuki Yoshizumi
- Department of Neurology, Hyogo Medical University, Nishinomiya, 663-8501 Hyogo, Japan
| | - Masamitsu Nishi
- Department of Neurology, Hyogo Medical University, Nishinomiya, 663-8501 Hyogo, Japan
| | - Masataka Igeta
- Department of Biostatistics, Hyogo Medical University, Nishinomiya, 663-8501 Hyogo, Japan
| | - Masayuki Nakamori
- Department of Neurology, Yamaguchi University Graduate School of Medicine, Yamaguchi, 755-8505 Yamaguchi, Japan
| | - Kimiko Inoue
- Department of Neurology, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, 560-8552 Osaka, Japan
| | - Tsuyoshi Matsumura
- Department of Neurology, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, 560-8552 Osaka, Japan
| | - Harutoshi Fujimura
- Department of Neurology, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, 560-8552 Osaka, Japan
| | - Kenji Jinnai
- Department of Neurology, National Hospital Organization Hyogo-Chuo Hospital, Sanda, 669-1515 Hyogo, Japan
| | - Takashi Kimura
- Department of Neurology, Hyogo Medical University, Nishinomiya, 663-8501 Hyogo, Japan.
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3
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Sanchez-Flores M, Corral-Juan M, Gasch-Navalón E, Cirillo D, Sanchez I, Matilla-Dueñas A. Novel genotype-phenotype correlations, differential cerebellar allele-specific methylation, and a common origin of the (ATTTC) n insertion in spinocerebellar ataxia type 37. Hum Genet 2024; 143:211-232. [PMID: 38396267 PMCID: PMC11043136 DOI: 10.1007/s00439-024-02644-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 01/17/2024] [Indexed: 02/25/2024]
Abstract
Spinocerebellar ataxia subtype 37 (SCA37) is a rare disease originally identified in ataxia patients from the Iberian Peninsula with a pure cerebellar syndrome. SCA37 patients carry a pathogenic intronic (ATTTC)n repeat insertion flanked by two polymorphic (ATTTT)n repeats in the Disabled-1 (DAB1) gene leading to cerebellar dysregulation. Herein, we determine the precise configuration of the pathogenic 5'(ATTTT)n-(ATTTC)n-3'(ATTTT)n SCA37 alleles by CRISPR-Cas9 and long-read nanopore sequencing, reveal their epigenomic signatures in SCA37 lymphocytes, fibroblasts, and cerebellar samples, and establish new molecular and clinical correlations. The 5'(ATTTT)n-(ATTTC)n-3'(ATTTT)n pathogenic allele configurations revealed repeat instability and differential methylation signatures. Disease age of onset negatively correlated with the (ATTTC)n, and positively correlated with the 3'(ATTTT)n. Geographic origin and gender significantly correlated with age of onset. Furthermore, significant predictive regression models were obtained by machine learning for age of onset and disease evolution by considering gender, the (ATTTC)n, the 3'(ATTTT)n, and seven CpG positions differentially methylated in SCA37 cerebellum. A common 964-kb genomic region spanning the (ATTTC)n insertion was identified in all SCA37 patients analysed from Portugal and Spain, evidencing a common origin of the SCA37 mutation in the Iberian Peninsula originating 859 years ago (95% CI 647-1378). In conclusion, we demonstrate an accurate determination of the size and configuration of the regulatory 5'(ATTTT)n-(ATTTC)n-3'(ATTTT)n repeat tract, avoiding PCR bias amplification using CRISPR/Cas9-enrichment and nanopore long-read sequencing, resulting relevant for accurate genetic diagnosis of SCA37. Moreover, we determine novel significant genotype-phenotype correlations in SCA37 and identify differential cerebellar allele-specific methylation signatures that may underlie DAB1 pathogenic dysregulation.
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Affiliation(s)
- Marina Sanchez-Flores
- Neurogenetics Unit, Department of Neuroscience, Germans Trias i Pujol Research Institute (IGTP), Universitat Autònoma de Barcelona-Can Ruti Campus, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Spain
| | - Marc Corral-Juan
- Neurogenetics Unit, Department of Neuroscience, Germans Trias i Pujol Research Institute (IGTP), Universitat Autònoma de Barcelona-Can Ruti Campus, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Spain
| | - Esther Gasch-Navalón
- Neurogenetics Unit, Department of Neuroscience, Germans Trias i Pujol Research Institute (IGTP), Universitat Autònoma de Barcelona-Can Ruti Campus, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Spain
| | | | - Ivelisse Sanchez
- Neurogenetics Unit, Department of Neuroscience, Germans Trias i Pujol Research Institute (IGTP), Universitat Autònoma de Barcelona-Can Ruti Campus, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Spain
| | - Antoni Matilla-Dueñas
- Neurogenetics Unit, Department of Neuroscience, Germans Trias i Pujol Research Institute (IGTP), Universitat Autònoma de Barcelona-Can Ruti Campus, Carretera de Can Ruti, Camí de les Escoles s/n, 08916, Badalona, Spain.
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4
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Mätlik K, Baffuto M, Kus L, Deshmukh AL, Davis DA, Paul MR, Carroll TS, Caron MC, Masson JY, Pearson CE, Heintz N. Cell-type-specific CAG repeat expansions and toxicity of mutant Huntingtin in human striatum and cerebellum. Nat Genet 2024; 56:383-394. [PMID: 38291334 PMCID: PMC10937393 DOI: 10.1038/s41588-024-01653-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 12/28/2023] [Indexed: 02/01/2024]
Abstract
Brain region-specific degeneration and somatic expansions of the mutant Huntingtin (mHTT) CAG tract are key features of Huntington's disease (HD). However, the relationships among CAG expansions, death of specific cell types and molecular events associated with these processes are not established. Here, we used fluorescence-activated nuclear sorting (FANS) and deep molecular profiling to gain insight into the properties of cell types of the human striatum and cerebellum in HD and control donors. CAG expansions arise at mHTT in striatal medium spiny neurons (MSNs), cholinergic interneurons and cerebellar Purkinje neurons, and at mutant ATXN3 in MSNs from SCA3 donors. CAG expansions in MSNs are associated with higher levels of MSH2 and MSH3 (forming MutSβ), which can inhibit nucleolytic excision of CAG slip-outs by FAN1. Our data support a model in which CAG expansions are necessary but may not be sufficient for cell death and identify transcriptional changes associated with somatic CAG expansions and striatal toxicity.
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Affiliation(s)
- Kert Mätlik
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Matthew Baffuto
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Laura Kus
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Amit Laxmikant Deshmukh
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - David A Davis
- Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Matthew R Paul
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - Thomas S Carroll
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - Marie-Christine Caron
- CHU de Québec Research Center, Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec, Canada
| | - Jean-Yves Masson
- CHU de Québec Research Center, Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec, Canada
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Nathaniel Heintz
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA.
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5
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Mätlik K, Baffuto M, Kus L, Deshmukh AL, Davis DA, Paul MR, Carroll TS, Caron MC, Masson JY, Pearson CE, Heintz N. Cell Type Specific CAG Repeat Expansions and Toxicity of Mutant Huntingtin in Human Striatum and Cerebellum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538082. [PMID: 37333326 PMCID: PMC10274669 DOI: 10.1101/2023.04.24.538082] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Brain region-specific degeneration and somatic expansions of the mutant Huntingtin (mHTT) CAG tract are key features of Huntington's disease (HD). However, the relationships between CAG expansions, death of specific cell types, and molecular events associated with these processes are not established. Here we employed fluorescence-activated nuclear sorting (FANS) and deep molecular profiling to gain insight into the properties of cell types of the human striatum and cerebellum in HD and control donors. CAG expansions arise in striatal medium spiny neurons (MSNs) and cholinergic interneurons, in cerebellar Purkinje neurons, and at mATXN3 in MSNs from SCA3 donors. CAG expansions in MSNs are associated with higher levels of MSH2 and MSH3 (forming MutSβ), which can inhibit nucleolytic excision of CAG slip-outs by FAN1 in a concentration-dependent manner. Our data indicate that ongoing CAG expansions are not sufficient for cell death, and identify transcriptional changes associated with somatic CAG expansions and striatal toxicity.
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6
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Hu N, Kim E, Antoury L, Wheeler TM. Correction of Clcn1 alternative splicing reverses muscle fiber type transition in mice with myotonic dystrophy. Nat Commun 2023; 14:1956. [PMID: 37029100 PMCID: PMC10082032 DOI: 10.1038/s41467-023-37619-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 03/21/2023] [Indexed: 04/09/2023] Open
Abstract
In myotonic dystrophy type 1 (DM1), deregulated alternative splicing of the muscle chloride channel Clcn1 causes myotonia, a delayed relaxation of muscles due to repetitive action potentials. The degree of weakness in adult DM1 is associated with increased frequency of oxidative muscle fibers. However, the mechanism for glycolytic-to-oxidative fiber type transition in DM1 and its relationship to myotonia are uncertain. Here we cross two mouse models of DM1 to create a double homozygous model that features progressive functional impairment, severe myotonia, and near absence of type 2B glycolytic fibers. Intramuscular injection of an antisense oligonucleotide for targeted skipping of Clcn1 exon 7a corrects Clcn1 alternative splicing, increases glycolytic 2B levels to ≥ 40% frequency, reduces muscle injury, and improves fiber hypertrophy relative to treatment with a control oligo. Our results demonstrate that fiber type transitions in DM1 result from myotonia and are reversible, and support the development of Clcn1-targeting therapies for DM1.
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Affiliation(s)
- Ningyan Hu
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Eunjoo Kim
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Layal Antoury
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Thurman M Wheeler
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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7
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Wang G, Vasquez KM. Dynamic alternative DNA structures in biology and disease. Nat Rev Genet 2023; 24:211-234. [PMID: 36316397 DOI: 10.1038/s41576-022-00539-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Abstract
Repetitive elements in the human genome, once considered 'junk DNA', are now known to adopt more than a dozen alternative (that is, non-B) DNA structures, such as self-annealed hairpins, left-handed Z-DNA, three-stranded triplexes (H-DNA) or four-stranded guanine quadruplex structures (G4 DNA). These dynamic conformations can act as functional genomic elements involved in DNA replication and transcription, chromatin organization and genome stability. In addition, recent studies have revealed a role for these alternative structures in triggering error-generating DNA repair processes, thereby actively enabling genome plasticity. As a driving force for genetic variation, non-B DNA structures thus contribute to both disease aetiology and evolution.
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Affiliation(s)
- Guliang Wang
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Paediatric Research Institute, Austin, TX, USA
| | - Karen M Vasquez
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Paediatric Research Institute, Austin, TX, USA.
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Morales F, Corrales E, Vásquez M, Zhang B, Fernández H, Alvarado F, Cortés S, Santamaría-Ulloa C, Initiative-Mmdbdi MMDBD, Krahe R, Monckton DG. Individual-specific levels of CTG•CAG somatic instability are shared across multiple tissues in myotonic dystrophy type 1. Hum Mol Genet 2023; 32:621-631. [PMID: 36099027 DOI: 10.1093/hmg/ddac231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 08/16/2022] [Accepted: 09/09/2022] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy type 1 is a complex disease caused by a genetically unstable CTG repeat expansion in the 3'-untranslated region of the DMPK gene. Age-dependent, tissue-specific somatic instability has confounded genotype-phenotype associations, but growing evidence suggests that it also contributes directly toward disease progression. Using a well-characterized clinical cohort of DM1 patients from Costa Rica, we quantified somatic instability in blood, buccal cells, skin and skeletal muscle. Whilst skeletal muscle showed the largest expansions, modal allele lengths in skin were also very large and frequently exceeded 2000 CTG repeats. Similarly, the degree of somatic expansion in blood, muscle and skin were associated with each other. Notably, we found that the degree of somatic expansion in skin was highly predictive of that in skeletal muscle. More importantly, we established that individuals whose repeat expanded more rapidly than expected in one tissue (after correction for progenitor allele length and age) also expanded more rapidly than expected in other tissues. We also provide evidence suggesting that individuals in whom the repeat expanded more rapidly than expected in skeletal muscle have an earlier age at onset than expected (after correction for the progenitor allele length). Pyrosequencing analyses of the genomic DNA flanking the CTG repeat revealed that the degree of methylation in muscle was well predicted by the muscle modal allele length and age, but that neither methylation of the flanking DNA nor levels of DMPK sense and anti-sense transcripts could obviously explain individual- or tissue-specific patterns of somatic instability.
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Affiliation(s)
- Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José 2060, Costa Rica
| | - Eyleen Corrales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José 2060, Costa Rica
| | - Melissa Vásquez
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José 2060, Costa Rica
| | - Baili Zhang
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030-4009, USA
| | - Huberth Fernández
- Hospital Calderón Guardia/Escuela de Medicina, Universidad de Costa Rica, San José 2060, Costa Rica
| | - Fernando Alvarado
- Hospital Calderón Guardia/Escuela de Medicina, Universidad de Costa Rica, San José 2060, Costa Rica
| | - Sergio Cortés
- Hospital Calderón Guardia/Escuela de Medicina, Universidad de Costa Rica, San José 2060, Costa Rica
| | | | | | - Ralf Krahe
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030-4009, USA
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
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Todorow V, Hintze S, Schoser B, Meinke P. Nuclear envelope transmembrane proteins involved in genome organization are misregulated in myotonic dystrophy type 1 muscle. Front Cell Dev Biol 2023; 10:1007331. [PMID: 36699009 PMCID: PMC9868253 DOI: 10.3389/fcell.2022.1007331] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 12/27/2022] [Indexed: 01/11/2023] Open
Abstract
Myotonic dystrophy type 1 is a multisystemic disorder with predominant muscle and neurological involvement. Despite a well described pathomechanism, which is primarily a global missplicing due to sequestration of RNA-binding proteins, there are still many unsolved questions. One such question is the disease etiology in the different affected tissues. We observed alterations at the nuclear envelope in primary muscle cell cultures before. This led us to reanalyze a published RNA-sequencing dataset of DM1 and control muscle biopsies regarding the misregulation of NE proteins. We could identify several muscle NE protein encoding genes to be misregulated depending on the severity of the muscle phenotype. Among these misregulated genes were NE transmembrane proteins (NETs) involved in nuclear-cytoskeletal coupling as well as genome organization. For selected genes, we could confirm that observed gene-misregulation led to protein expression changes. Furthermore, we investigated if genes known to be under expression-regulation by genome organization NETs were also misregulated in DM1 biopsies, which revealed that misregulation of two NETs alone is likely responsible for differential expression of about 10% of all genes being differentially expressed in DM1. Notably, the majority of NETs identified here to be misregulated in DM1 muscle are mutated in Emery-Dreifuss muscular dystrophy or clinical similar muscular dystrophies, suggesting a broader similarity on the molecular level for muscular dystrophies than anticipated. This shows not only the importance of muscle NETs in muscle health and disease, but also highlights the importance of the NE in DM1 disease progression.
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Di Leo V, Lawless C, Roussel MP, Gomes TB, Gorman GS, Russell OM, Tuppen HA, Duchesne E, Vincent AE. Resistance Exercise Training Rescues Mitochondrial Dysfunction in Skeletal Muscle of Patients with Myotonic Dystrophy Type 1. J Neuromuscul Dis 2023; 10:1111-1126. [PMID: 37638448 PMCID: PMC10657683 DOI: 10.3233/jnd-230099] [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] [Accepted: 08/08/2023] [Indexed: 08/29/2023]
Abstract
BACKGROUND Myotonic dystrophy type 1 (DM1) is a dominant autosomal neuromuscular disorder caused by the inheritance of a CTG triplet repeat expansion in the Dystrophia Myotonica Protein Kinase (DMPK) gene. At present, no cure currently exists for DM1 disease. OBJECTIVE This study investigates the effects of 12-week resistance exercise training on mitochondrial oxidative phosphorylation in skeletal muscle in a cohort of DM1 patients (n = 11, men) in comparison to control muscle with normal oxidative phosphorylation. METHODS Immunofluorescence was used to assess protein levels of key respiratory chain subunits of complex I (CI) and complex IV (CIV), and markers of mitochondrial mass and cell membrane in individual myofibres sampled from muscle biopsies. Using control's skeletal muscle fibers population, we classified each patient's fibers as having normal, low or high levels of CI and CIV and compared the proportions of fibers before and after exercise training. The significance of changes observed between pre- and post-exercise within patients was estimated using a permutation test. RESULTS At baseline, DM1 patients present with significantly decreased mitochondrial mass, and isolated or combined CI and CIV deficiency. After resistance exercise training, in most patients a significant increase in mitochondrial mass was observed, and all patients showed a significant increase in CI and/or CIV protein levels. Moreover, improvements in mitochondrial mass were correlated with the one-repetition maximum strength evaluation. CONCLUSIONS Remarkably, 12-week resistance exercise training is sufficient to partially rescue mitochondrial dysfunction in DM1 patients, suggesting that the response to exercise is in part be due to changes in mitochondria.
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Affiliation(s)
- Valeria Di Leo
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
| | - Conor Lawless
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
| | - Marie-Pier Roussel
- Department of Fundamental Sciences, Université du Québec à Chicoutimi, Quebec, Canada
| | - Tiago B. Gomes
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle Upon Tyne, UK
| | - Gráinne S. Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle Upon Tyne, UK
| | - Oliver M. Russell
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
| | - Helen A.L. Tuppen
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
| | - Elise Duchesne
- Department of Health Sciences, Université du Québec à Chicoutimi, Québec, Canada
- Neuromuscular Diseases Interdisciplinary Research Group (GRIMN), Saguenay-Lac-St-Jean Integrated University Health and Social Services Center, Saguenay, QC, Canada
| | - Amy E. Vincent
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, UK
- NIHR Newcastle Biomedical Research Centre, Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, Newcastle upon Tyne, England
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11
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Abstract
PURPOSE OF REVIEW Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are genetic disorders affecting skeletal and smooth muscle, heart, brain, eyes, and other organs. The multisystem involvement and disease variability of myotonic dystrophy have presented challenges for clinical care and research. This article focuses on the diagnosis and management of the disease. In addition, recent advances in characterizing the diverse clinical manifestations and variability of the disease are discussed. RECENT FINDINGS Studies of the multisystem involvement of myotonic dystrophy, including the most lethal cardiac and respiratory manifestations and their molecular underpinnings, expand our understanding of the myotonic dystrophy phenotype. Advances have been made in understanding the molecular mechanisms of both types of myotonic dystrophy, providing opportunities for developing targeted therapeutics, some of which have entered clinical trials in DM1. SUMMARY Continued efforts focus on advancing our molecular and clinical understanding of DM1 and DM2. Accurately measuring and monitoring the diverse and variable clinical manifestations of myotonic dystrophy in clinic and in research is important to provide adequate care, prevent complications, and find treatments that improve symptoms and life quality.
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12
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Mohiuddin M, Kooy RF, Pearson CE. De novo mutations, genetic mosaicism and human disease. Front Genet 2022; 13:983668. [PMID: 36226191 PMCID: PMC9550265 DOI: 10.3389/fgene.2022.983668] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/08/2022] [Indexed: 11/23/2022] Open
Abstract
Mosaicism—the existence of genetically distinct populations of cells in a particular organism—is an important cause of genetic disease. Mosaicism can appear as de novo DNA mutations, epigenetic alterations of DNA, and chromosomal abnormalities. Neurodevelopmental or neuropsychiatric diseases, including autism—often arise by de novo mutations that usually not present in either of the parents. De novo mutations might occur as early as in the parental germline, during embryonic, fetal development, and/or post-natally, through ageing and life. Mutation timing could lead to mutation burden of less than heterozygosity to approaching homozygosity. Developmental timing of somatic mutation attainment will affect the mutation load and distribution throughout the body. In this review, we discuss the timing of de novo mutations, spanning from mutations in the germ lineage (all ages), to post-zygotic, embryonic, fetal, and post-natal events, through aging to death. These factors can determine the tissue specific distribution and load of de novo mutations, which can affect disease. The disease threshold burden of somatic de novo mutations of a particular gene in any tissue will be important to define.
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Affiliation(s)
- Mohiuddin Mohiuddin
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
- *Correspondence: Mohiuddin Mohiuddin, ; Christopher E. Pearson,
| | - R. Frank Kooy
- Department of Medical Genetics, University of Antwerp, Edegem, Belgium
| | - Christopher E. Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- *Correspondence: Mohiuddin Mohiuddin, ; Christopher E. Pearson,
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13
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Kelley CP, Haerle MC, Wang ET. Negative autoregulation mitigates collateral RNase activity of repeat-targeting CRISPR-Cas13d in mammalian cells. Cell Rep 2022; 40:111226. [PMID: 35977479 PMCID: PMC9809062 DOI: 10.1016/j.celrep.2022.111226] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/29/2022] [Accepted: 07/26/2022] [Indexed: 01/05/2023] Open
Abstract
CRISPR-Cas13 RNA endonucleases show promise for programmable RNA knockdown. However, sequence-specific binding of Cas13 unleashes non-specific bystander RNA cleavage, or collateral activity, raising concerns for experiments and therapeutic applications. Although robust in cell-free and bacterial environments, collateral activity in mammalian cells remains disputed. We investigate Cas13d collateral activity in a therapeutic context for myotonic dystrophy type 1, caused by a transcribed CTG repeat expansion. We find that, when targeting CUGn RNA in mammalian cells, Cas13d depletes endogenous and transgenic RNAs, interferes with critical cellular processes, and activates stress response and apoptosis. Collateral effects also occur when targeting abundant endogenous transcripts. To minimize collateral activity for repeat-targeting approaches, we introduce GENO, an adeno-associated virus-compatible strategy that leverages guide RNA processing to control Cas13d expression. We argue that thorough assessment of collateral activity is necessary when applying Cas13 in mammalian cells and that GENO illustrates advantages of compact regulatory systems for Cas-based gene therapies.
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Affiliation(s)
- Chase P Kelley
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL 32608, USA; Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL 32608, USA
| | - Maja C Haerle
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL 32608, USA
| | - Eric T Wang
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL 32608, USA; Myology Institute, University of Florida, Gainesville, FL 32608, USA.
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14
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Barbé L, Finkbeiner S. Genetic and Epigenetic Interplay Define Disease Onset and Severity in Repeat Diseases. Front Aging Neurosci 2022; 14:750629. [PMID: 35592702 PMCID: PMC9110800 DOI: 10.3389/fnagi.2022.750629] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 03/01/2022] [Indexed: 11/13/2022] Open
Abstract
Repeat diseases, such as fragile X syndrome, myotonic dystrophy, Friedreich ataxia, Huntington disease, spinocerebellar ataxias, and some forms of amyotrophic lateral sclerosis, are caused by repetitive DNA sequences that are expanded in affected individuals. The age at which an individual begins to experience symptoms, and the severity of disease, are partially determined by the size of the repeat. However, the epigenetic state of the area in and around the repeat also plays an important role in determining the age of disease onset and the rate of disease progression. Many repeat diseases share a common epigenetic pattern of increased methylation at CpG islands near the repeat region. CpG islands are CG-rich sequences that are tightly regulated by methylation and are often found at gene enhancer or insulator elements in the genome. Methylation of CpG islands can inhibit binding of the transcriptional regulator CTCF, resulting in a closed chromatin state and gene down regulation. The downregulation of these genes leads to some disease-specific symptoms. Additionally, a genetic and epigenetic interplay is suggested by an effect of methylation on repeat instability, a hallmark of large repeat expansions that leads to increasing disease severity in successive generations. In this review, we will discuss the common epigenetic patterns shared across repeat diseases, how the genetics and epigenetics interact, and how this could be involved in disease manifestation. We also discuss the currently available stem cell and mouse models, which frequently do not recapitulate epigenetic patterns observed in human disease, and propose alternative strategies to study the role of epigenetics in repeat diseases.
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Affiliation(s)
- Lise Barbé
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, United States
- Department of Neurology, University of California, San Francisco, San Francisco, CA, United States
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
| | - Steve Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, United States
- Department of Neurology, University of California, San Francisco, San Francisco, CA, United States
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
- *Correspondence: Steve Finkbeiner,
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15
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García-Puga M, Saenz-Antoñanzas A, Matheu A, López de Munain A. Targeting Myotonic Dystrophy Type 1 with Metformin. Int J Mol Sci 2022; 23:ijms23052901. [PMID: 35270043 PMCID: PMC8910924 DOI: 10.3390/ijms23052901] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 02/01/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic disorder of genetic origin. Progressive muscular weakness, atrophy and myotonia are its most prominent neuromuscular features, while additional clinical manifestations in multiple organs are also common. Overall, DM1 features resemble accelerated aging. There is currently no cure or specific treatment for myotonic dystrophy patients. However, in recent years a great effort has been made to identify potential new therapeutic strategies for DM1 patients. Metformin is a biguanide antidiabetic drug, with potential to delay aging at cellular and organismal levels. In DM1, different studies revealed that metformin rescues multiple phenotypes of the disease. This review provides an overview of recent findings describing metformin as a novel therapy to combat DM1 and their link with aging.
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Affiliation(s)
- Mikel García-Puga
- Neuromuscular Diseases Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Cellular Oncology Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED-CIBER), Carlos III Institute, 28031 Madrid, Spain
| | - Ander Saenz-Antoñanzas
- Cellular Oncology Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
| | - Ander Matheu
- Cellular Oncology Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Basque Foundation for Science (IKERBASQUE), 48009 Bilbao, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERfes), Carlos III Institute, 28029 Madrid, Spain
- Correspondence: (A.M.); (A.L.d.M.); Tel.: +34-943-006-073 (A.M.); +34-943-006-294 (A.L.d.M.)
| | - Adolfo López de Munain
- Neuromuscular Diseases Group, Biodonostia Health Research Institute, 20014 San Sebastian, Spain;
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED-CIBER), Carlos III Institute, 28031 Madrid, Spain
- Neurology Department, Donostia University Hospital, OSAKIDETZA, 20014 San Sebastian, Spain
- Department of Neurosciences, Faculty of Medicine and Nursery, University of the Basque Country, 20014 San Sebastian, Spain
- Correspondence: (A.M.); (A.L.d.M.); Tel.: +34-943-006-073 (A.M.); +34-943-006-294 (A.L.d.M.)
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16
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Myotonic Dystrophies: A Genetic Overview. Genes (Basel) 2022; 13:genes13020367. [PMID: 35205411 PMCID: PMC8872148 DOI: 10.3390/genes13020367] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/09/2022] [Accepted: 02/16/2022] [Indexed: 02/01/2023] Open
Abstract
Myotonic dystrophies (DM) are the most common muscular dystrophies in adults, which can affect other non-skeletal muscle organs such as the heart, brain and gastrointestinal system. There are two genetically distinct types of myotonic dystrophy: myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2), both dominantly inherited with significant overlap in clinical manifestations. DM1 results from CTG repeat expansions in the 3′-untranslated region (3′UTR) of the DMPK (dystrophia myotonica protein kinase) gene on chromosome 19, while DM2 is caused by CCTG repeat expansions in intron 1 of the CNBP (cellular nucleic acid-binding protein) gene on chromosome 3. Recent advances in genetics and molecular biology, especially in the field of RNA biology, have allowed better understanding of the potential pathomechanisms involved in DM. In this review article, core clinical features and genetics of DM are presented followed by a discussion on the current postulated pathomechanisms and therapeutic approaches used in DM, including the ones currently in human clinical trial phase.
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17
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Molecular and Clinical Implications of Variant Repeats in Myotonic Dystrophy Type 1. Int J Mol Sci 2021; 23:ijms23010354. [PMID: 35008780 PMCID: PMC8745394 DOI: 10.3390/ijms23010354] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/14/2021] [Accepted: 12/18/2021] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is one of the most variable monogenic diseases at phenotypic, genetic, and epigenetic level. The disease is multi-systemic with the age at onset ranging from birth to late age. The underlying mutation is an unstable expansion of CTG repeats in the DMPK gene, varying in size from 50 to >1000 repeats. Generally, large expansions are associated with an earlier age at onset. Additionally, the most severe, congenital DM1 form is typically associated with local DNA methylation. Genetic variability of DM1 mutation is further increased by its structural variations due to presence of other repeats (e.g., CCG, CTC, CAG). These variant repeats or repeat interruptions seem to confer an additional level of epigenetic variability since local DNA methylation is frequently associated with variant CCG repeats independently of the expansion size. The effect of repeat interruptions on DM1 molecular pathogenesis is not investigated enough. Studies on patients indicate their stabilizing effect on DMPK expansions because no congenital cases were described in patients with repeat interruptions, and the age at onset is frequently later than expected. Here, we review the clinical relevance of repeat interruptions in DM1 and genetic and epigenetic characteristics of interrupted DMPK expansions based on patient studies.
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18
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Cardiac Pathology in Myotonic Dystrophy Type 1. Int J Mol Sci 2021; 22:ijms222111874. [PMID: 34769305 PMCID: PMC8584352 DOI: 10.3390/ijms222111874] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 01/08/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy affecting adults and children, is a multi-systemic disorder affecting skeletal, cardiac, and smooth muscles as well as neurologic, endocrine and other systems. This review is on the cardiac pathology associated with DM1. The heart is one of the primary organs affected in DM1. Cardiac conduction defects are seen in up to 75% of adult DM1 cases and sudden death due to cardiac arrhythmias is one of the most common causes of death in DM1. Unfortunately, the pathogenesis of cardiac manifestations in DM1 is ill defined. In this review, we provide an overview of the history of cardiac studies in DM1, clinical manifestations, and pathology of the heart in DM1. This is followed by a discussion of emerging data about the utility of cardiac magnetic resonance imaging (CMR) as a biomarker for cardiac disease in DM1, and ends with a discussion on models of cardiac RNA toxicity in DM1 and recent clinical guidelines for cardiologic management of individuals with DM1.
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19
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Malik I, Kelley CP, Wang ET, Todd PK. Molecular mechanisms underlying nucleotide repeat expansion disorders. Nat Rev Mol Cell Biol 2021; 22:589-607. [PMID: 34140671 PMCID: PMC9612635 DOI: 10.1038/s41580-021-00382-6] [Citation(s) in RCA: 131] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2021] [Indexed: 02/05/2023]
Abstract
The human genome contains over one million short tandem repeats. Expansion of a subset of these repeat tracts underlies over fifty human disorders, including common genetic causes of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (C9orf72), polyglutamine-associated ataxias and Huntington disease, myotonic dystrophy, and intellectual disability disorders such as Fragile X syndrome. In this Review, we discuss the four major mechanisms by which expansion of short tandem repeats causes disease: loss of function through transcription repression, RNA-mediated gain of function through gelation and sequestration of RNA-binding proteins, gain of function of canonically translated repeat-harbouring proteins, and repeat-associated non-AUG translation of toxic repeat peptides. Somatic repeat instability amplifies these mechanisms and influences both disease age of onset and tissue specificity of pathogenic features. We focus on the crosstalk between these disease mechanisms, and argue that they often synergize to drive pathogenesis. We also discuss the emerging native functions of repeat elements and how their dynamics might contribute to disease at a larger scale than currently appreciated. Lastly, we propose that lynchpins tying these disease mechanisms and native functions together offer promising therapeutic targets with potential shared applications across this class of human disorders.
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Affiliation(s)
- Indranil Malik
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Chase P Kelley
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA
- Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA.
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
- VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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20
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Morales F, Vásquez M, Corrales E, Vindas-Smith R, Santamaría-Ulloa C, Zhang B, Sirito M, Estecio MR, Krahe R, Monckton DG. Longitudinal increases in somatic mosaicism of the expanded CTG repeat in myotonic dystrophy type 1 are associated with variation in age-at-onset. Hum Mol Genet 2021; 29:2496-2507. [PMID: 32601694 DOI: 10.1093/hmg/ddaa123] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 04/13/2020] [Accepted: 06/16/2020] [Indexed: 12/26/2022] Open
Abstract
In myotonic dystrophy type 1 (DM1), somatic mosaicism of the (CTG)n repeat expansion is age-dependent, tissue-specific and expansion-biased. These features contribute toward variation in disease severity and confound genotype-to-phenotype analyses. To investigate how the (CTG)n repeat expansion changes over time, we collected three longitudinal blood DNA samples separated by 8-15 years and used small pool and single-molecule PCR in 43 DM1 patients. We used the lower boundary of the allele length distribution as the best estimate for the inherited progenitor allele length (ePAL), which is itself the best predictor of disease severity. Although in most patients the lower boundary of the allele length distribution was conserved over time, in many this estimate also increased with age, suggesting samples for research studies and clinical trials should be obtained as early as possible. As expected, the modal allele length increased over time, driven primarily by ePAL, age-at-sampling and the time interval. As expected, small expansions <100 repeats did not expand as rapidly as larger alleles. However, the rate of expansion of very large alleles was not obviously proportionally higher. This may, at least in part, be a result of the allele length-dependent increase in large contractions that we also observed. We also determined that individual-specific variation in the increase of modal allele length over time not accounted for by ePAL, age-at-sampling and time was inversely associated with individual-specific variation in age-at-onset not accounted for by ePAL, further highlighting somatic expansion as a therapeutic target in DM1.
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Affiliation(s)
- Fernando Morales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, Costa Rica
| | - Melissa Vásquez
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, Costa Rica
| | - Eyleen Corrales
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, Costa Rica
| | - Rebeca Vindas-Smith
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, Costa Rica
| | | | - Baili Zhang
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mario Sirito
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Marcos R Estecio
- Department of Epigenetics & Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Ralf Krahe
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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21
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Todorow V, Hintze S, Kerr ARW, Hehr A, Schoser B, Meinke P. Transcriptome Analysis in a Primary Human Muscle Cell Differentiation Model for Myotonic Dystrophy Type 1. Int J Mol Sci 2021; 22:8607. [PMID: 34445314 PMCID: PMC8395314 DOI: 10.3390/ijms22168607] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/30/2021] [Accepted: 08/06/2021] [Indexed: 01/01/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is caused by CTG-repeat expansions leading to a complex pathology with a multisystemic phenotype that primarily affects the muscles and brain. Despite a multitude of information, especially on the alternative splicing of several genes involved in the pathology, information about additional factors contributing to the disease development is still lacking. We performed RNAseq and gene expression analyses on proliferating primary human myoblasts and differentiated myotubes. GO-term analysis indicates that in myoblasts and myotubes, different molecular pathologies are involved in the development of the muscular phenotype. Gene set enrichment for splicing reveals the likelihood of whole, differentiation stage specific, splicing complexes that are misregulated in DM1. These data add complexity to the alternative splicing phenotype and we predict that it will be of high importance for therapeutic interventions to target not only mature muscle, but also satellite cells.
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Affiliation(s)
- Vanessa Todorow
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University Munich, 80336 Munich, Germany
| | - Stefan Hintze
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University Munich, 80336 Munich, Germany
| | - Alastair R W Kerr
- Cancer Biomarker Centre, CRUK Manchester Institute, University of Manchester, Manchester SK10 4TG, UK
| | - Andreas Hehr
- Centre for Human Genetics, 93047 Regensburg, Germany
| | - Benedikt Schoser
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University Munich, 80336 Munich, Germany
| | - Peter Meinke
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University Munich, 80336 Munich, Germany
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22
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Hintze S, Mensel R, Knaier L, Schoser B, Meinke P. CTG-Repeat Detection in Primary Human Myoblasts of Myotonic Dystrophy Type 1. Front Neurosci 2021; 15:686735. [PMID: 34262431 PMCID: PMC8274452 DOI: 10.3389/fnins.2021.686735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 06/07/2021] [Indexed: 11/18/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystemic disorder caused by unstable CTG-repeat expansions in the DMPK gene. Tissue mosaicism has been described for the length of these repeat expansions. The most obvious affected tissue is skeletal muscle, making it the first target for therapy development. To date there is no approved therapy despite some existing approaches. Thus, there is the demand to further advance therapeutic developments, which will in return require several well-characterized preclinical tools and model systems. Here we describe a modified method to identify the CTG-repeat length in primary human myoblasts isolated from DM1 patients that requires less genomic DNA and avoids radioactive labeling. Using this method, we show that primary human DM1 myoblast cultures represent a population of cells with different CTG-repeat length. Comparing DNA from the identical muscle biopsy specimen, the range of CTG-repeat length in the myoblast culture is within the same range of the muscle biopsy specimen. In conclusion, primary human DM1 myoblast cultures are a well-suited model to investigate certain aspects of the DM1 pathology. They are a useful platform to perform first-line investigations of preclinical therapies.
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Affiliation(s)
- Stefan Hintze
- Department of Neurology, LMU Klinikum, Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Raphaela Mensel
- Department of Neurology, LMU Klinikum, Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Lisa Knaier
- Department of Neurology, LMU Klinikum, Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Benedikt Schoser
- Department of Neurology, LMU Klinikum, Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Peter Meinke
- Department of Neurology, LMU Klinikum, Friedrich-Baur-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
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23
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Nguyen Q, Yokota T. Degradation of Toxic RNA in Myotonic Dystrophy Using Gapmer Antisense Oligonucleotides. Methods Mol Biol 2021; 2176:99-109. [PMID: 32865785 DOI: 10.1007/978-1-0716-0771-8_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Myotonic dystrophy (DM) types 1 (DM1) and 2 (DM2) are caused by autosomal dominant gain-of-function RNA which are, in turn, created by the expansion of repeat sequences in the DMPK and ZNF9 genes, respectively. The expansions are highly unstable and biased for further expansion in somatic cells and across generations. Despite the different genes involved, DM1 and DM2 share several clinical features due to having the similar underlying mechanism of repetitive RNA-mediated toxicity. Both disorders manifest as multisystemic conditions with features including myotonia, cataract development, and abnormalities in cardiac conduction. At present, there is no cure for DM and treatments mostly aim at symptom management. Among the therapeutics being developed, antisense therapy using gapmers is one of the most promising. Compared to other antisense oligonucleotides, gapmers maintain the ability to induce RNase H cleavage while having enhanced target binding affinity and nuclease resistance. This chapter will consolidate the different strategies studied thus far to develop a treatment for DM1 through the targeting of toxic repetitive RNA using gapmers.
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Affiliation(s)
- Quynh Nguyen
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Toshifumi Yokota
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
- The Friends of Garret Cumming Research and Muscular Dystrophy Canada HM Toupin Neurological Science Research Chair, Edmonton, AB, Canada.
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24
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Monckton DG. The Contribution of Somatic Expansion of the CAG Repeat to Symptomatic Development in Huntington's Disease: A Historical Perspective. J Huntingtons Dis 2021; 10:7-33. [PMID: 33579863 PMCID: PMC7990401 DOI: 10.3233/jhd-200429] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The discovery in the early 1990s of the expansion of unstable simple sequence repeats as the causative mutation for a number of inherited human disorders, including Huntington’s disease (HD), opened up a new era of human genetics and provided explanations for some old problems. In particular, an inverse association between the number of repeats inherited and age at onset, and unprecedented levels of germline instability, biased toward further expansion, provided an explanation for the wide symptomatic variability and anticipation observed in HD and many of these disorders. The repeats were also revealed to be somatically unstable in a process that is expansion-biased, age-dependent and tissue-specific, features that are now increasingly recognised as contributory to the age-dependence, progressive nature and tissue specificity of the symptoms of HD, and at least some related disorders. With much of the data deriving from affected individuals, and model systems, somatic expansions have been revealed to arise in a cell division-independent manner in critical target tissues via a mechanism involving key components of the DNA mismatch repair pathway. These insights have opened new approaches to thinking about how the disease could be treated by suppressing somatic expansion and revealed novel protein targets for intervention. Exciting times lie ahead in turning these insights into novel therapies for HD and related disorders.
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Affiliation(s)
- Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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25
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Gomes-Pereira M, Monckton DG. Chronic Exposure to Cadmium and Antioxidants Does Not Affect the Dynamics of Expanded CAG•CTG Trinucleotide Repeats in a Mouse Cell Culture System of Unstable DNA. Front Cell Neurosci 2021; 14:606331. [PMID: 33603644 PMCID: PMC7884634 DOI: 10.3389/fncel.2020.606331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/29/2020] [Indexed: 12/02/2022] Open
Abstract
More than 30 human disorders are caused by the expansion of simple sequence DNA repeats, among which triplet repeats remain the most frequent. Most trinucleotide repeat expansion disorders affect primarily the nervous system, through mechanisms of neurodysfunction and/or neurodegeneration. While trinucleotide repeat tracts are short and stably transmitted in unaffected individuals, disease-associated expansions are highly dynamic in the germline and in somatic cells, with a tendency toward further expansion. Since longer repeats are associated with increasing disease severity and earlier onset of symptoms, intergenerational repeat size gains account for the phenomenon of anticipation. In turn, higher levels of age-dependent somatic expansion have been linked with increased disease severity and earlier age of onset, implicating somatic instability in the onset and progression of disease symptoms. Hence, tackling the root cause of symptoms through the control of repeat dynamics may provide therapeutic modulation of clinical manifestations. DNA repair pathways have been firmly implicated in the molecular mechanism of repeat length mutation. The demonstration that repeat expansion depends on functional DNA mismatch repair (MMR) proteins, points to MMR as a potential therapeutic target. Similarly, a role of DNA base excision repair (BER) in repeat expansion has also been suggested, particularly during the removal of oxidative lesions. Using a well-characterized mouse cell model system of an unstable CAG•CTG trinucleotide repeat, we tested if expanded repeat tracts can be stabilized by small molecules with reported roles in both pathways: cadmium (an inhibitor of MMR activity) and a variety of antioxidants (capable of neutralizing oxidative species). We found that chronic exposure to sublethal doses of cadmium and antioxidants did not result in significant reduction of the rate of trinucleotide repeat expansion. Surprisingly, manganese yielded a significant stabilization of the triplet repeat tract. We conclude that treatment with cadmium and antioxidants, at doses that do not interfere with cell survival and cell culture dynamics, is not sufficient to modify trinucleotide repeat dynamics in cell culture.
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Affiliation(s)
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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26
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Leddy S, Serra L, Esposito D, Vizzotto C, Giulietti G, Silvestri G, Petrucci A, Meola G, Lopiano L, Cercignani M, Bozzali M. Lesion distribution and substrate of white matter damage in myotonic dystrophy type 1: Comparison with multiple sclerosis. NEUROIMAGE-CLINICAL 2021; 29:102562. [PMID: 33516936 PMCID: PMC7848627 DOI: 10.1016/j.nicl.2021.102562] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 01/06/2021] [Accepted: 01/08/2021] [Indexed: 02/08/2023]
Abstract
The supratentorial distribution of lesions is similar in DM1 and MS. Patients with DM1 do not show infratentorial lesions. Quantitative magnetization transfer supports the presence of demyelination in DM1 lesions, but not in the NAWM. Anterior temporal lobe lesions in DM1 might have a different substrate than periventricular ones.
Myotonic Dystrophy type 1 (DM1) is an autosomal dominant condition caused by expansion of the CTG triplet repeats within the myotonic dystrophy protein of the kinase (DMPK) gene. The central nervous system is involved in the disease, with multiple symptoms including cognitive impairment. A typical feature of DM1 is the presence of widespread white matter (WM) lesions, whose total volume is associated with CTG triplet expansion. The aim of this study was to characterize the distribution and pathological substrate of these lesions as well as the normal appearing WM (NAWM) using quantitative magnetization transfer (qMT) MRI, and comparing data from DM1 patients with those from patients with multiple sclerosis (MS). Twenty-eight patients with DM1, 29 patients with relapsing-remitting MS, and 15 healthy controls had an MRI scan, including conventional and qMT imaging. The average pool size ratio (F), a proxy of myelination, was computed within lesions and NAWM for every participant. The lesion masks were warped into MNI space and lesion probability maps were obtained for each patient group. The lesion distribution, total lesion load and the tissue-specific mean F were compared between groups. The supratentorial distribution of lesions was similar in the 2 patient groups, although mean lesion volume was higher in MS than DM1. DM1 presented higher prevalence of anterior temporal lobe lesions, but none in the cerebellum and brainstem. Significantly reduced F values were found within DM1 lesions, suggesting a loss of myelin density. While F was reduced in the NAWM of MS patients, it did not differ between DM1 and controls. Our results provide further evidence for a need to compare histology and imaging using new MRI techniques in DM1 patients, in order to further our understanding of the underlying disease process contributing to WM disease.
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Affiliation(s)
- Sara Leddy
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom; Brighton and Sussex University Hospital Trust, Brighton, United Kingdom
| | - Laura Serra
- Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy
| | - Davide Esposito
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom
| | - Camilla Vizzotto
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom
| | | | - Gabriella Silvestri
- Department of Neuroscience, Fondazione Policlinico Gemelli IRCCS, Università Cattolica del S. Cuore, Rome, Italy
| | - Antonio Petrucci
- UOC Neurologia e Neurofisiopatologia, AO San Camillo Forlanini, Rome, Italy
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa di Cura Policlinico, Milan, Italy; Department of Biomedical Science for Health, University of Milan, Milan, Italy
| | - Leonardo Lopiano
- 'Rita Levi Montalcini' Department of Neuroscience, University of Torino, Turin, Italy
| | - Mara Cercignani
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom; Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy
| | - Marco Bozzali
- Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom; UOC Neurologia e Neurofisiopatologia, AO San Camillo Forlanini, Rome, Italy.
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27
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Otero BA, Poukalov K, Hildebrandt RP, Thornton CA, Jinnai K, Fujimura H, Kimura T, Hagerman KA, Sampson JB, Day JW, Wang ET. Transcriptome alterations in myotonic dystrophy frontal cortex. Cell Rep 2021; 34:108634. [PMID: 33472074 PMCID: PMC9272850 DOI: 10.1016/j.celrep.2020.108634] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/16/2020] [Accepted: 12/21/2020] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy (DM) is caused by expanded CTG/CCTG repeats, causing symptoms in skeletal muscle, heart, and central nervous system (CNS). CNS issues are debilitating and include hypersomnolence, executive dysfunction, white matter atrophy, and neurofibrillary tangles. Here, we generate RNA-seq transcriptomes from DM and unaffected frontal cortex and identify 130 high-confidence splicing changes, most occurring only in cortex, not skeletal muscle or heart. Mis-spliced exons occur in neurotransmitter receptors, ion channels, and synaptic scaffolds, and GRIP1 mis-splicing modulates kinesin association. Optical mapping of expanded CTG repeats reveals extreme mosaicism, with some alleles showing >1,000 CTGs. Mis-splicing severity correlates with CTG repeat length across individuals. Upregulated genes tend to be microglial and endothelial, suggesting neuroinflammation, and downregulated genes tend to be neuronal. Many gene expression changes strongly correlate with mis-splicing, suggesting candidate biomarkers of disease. These findings provide a framework for mechanistic and therapeutic studies of the DM CNS. Otero et al. characterize DM1 frontal cortex transcriptomes and observe extreme CTG repeat lengths even in individuals showing modest mis-splicing. Mis-splicing is enriched in ion channels, neurotransmitter receptors, and synaptic scaffolds, in some cases potentially altering synaptic trafficking. Inferred expression signatures from microglia and endothelial cells suggest neuroinflammation.
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Affiliation(s)
- Brittney A Otero
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Kiril Poukalov
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Ryan P Hildebrandt
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Charles A Thornton
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Kenji Jinnai
- Department of Neurology, National Hospital Organization Hyogo-Chuo Hospital, Sanda, Japan
| | - Harutoshi Fujimura
- Department of Neurology, National Hospital Organization Toneyama Hospital, Osaka, Japan
| | - Takashi Kimura
- Department of Neurology, Hyogo College of Medicine, Nichinomiya, Japan
| | | | | | - John W Day
- Department of Neurology, Stanford University, Palo Alto, CA, USA
| | - Eric T Wang
- Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA.
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28
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Marsh S, Hanson B, Wood MJA, Varela MA, Roberts TC. Application of CRISPR-Cas9-Mediated Genome Editing for the Treatment of Myotonic Dystrophy Type 1. Mol Ther 2020; 28:2527-2539. [PMID: 33171139 PMCID: PMC7704741 DOI: 10.1016/j.ymthe.2020.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/03/2020] [Accepted: 10/08/2020] [Indexed: 12/15/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a debilitating multisystemic disorder, caused by expansion of a CTG microsatellite repeat in the 3' untranslated region of the DMPK (dystrophia myotonica protein kinase) gene. To date, novel therapeutic approaches have focused on transient suppression of the mutant, repeat-expanded RNA. However, recent developments in the field of genome editing have raised the exciting possibility of inducing permanent correction of the DM1 genetic defect. Specifically, repurposing of the prokaryotic CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 (CRISPR-associated protein 9) system has enabled programmable, site-specific, and multiplex genome editing. CRISPR-based strategies for the treatment of DM1 can be applied either directly to patients, or indirectly through the ex vivo modification of patient-derived cells, and they include excision of the repeat expansion, insertion of synthetic polyadenylation signals upstream of the repeat, steric interference with RNA polymerase II procession through the repeat leading to transcriptional downregulation of DMPK, and direct RNA targeting of the mutant RNA species. Potential obstacles to such therapies are discussed, including the major challenge of Cas9 and guide RNA transgene/ribonuclear protein delivery, off-target gene editing, vector genome insertion at cut sites, on-target unintended mutagenesis (e.g., repeat inversion), pre-existing immunity to Cas9 or AAV antigens, immunogenicity, and Cas9 persistence.
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Affiliation(s)
- Seren Marsh
- University of Oxford Medical School, Medical Sciences Division, University of Oxford, Oxford OX3 9DU, UK
| | - Britt Hanson
- Department of Physiology, Anatomy and Genetics, Oxford OX1 3QX, UK; Department of Paediatrics, University of Oxford, Oxford OX1 3QX, UK
| | - Matthew J A Wood
- Department of Paediatrics, University of Oxford, Oxford OX1 3QX, UK; MDUK Oxford Neuromuscular Centre, UK
| | - Miguel A Varela
- Department of Paediatrics, University of Oxford, Oxford OX1 3QX, UK
| | - Thomas C Roberts
- Department of Paediatrics, University of Oxford, Oxford OX1 3QX, UK; MDUK Oxford Neuromuscular Centre, UK.
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29
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Antisense oligonucleotide and adjuvant exercise therapy reverse fatigue in old mice with myotonic dystrophy. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 23:393-405. [PMID: 33473325 PMCID: PMC7787993 DOI: 10.1016/j.omtn.2020.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 11/17/2020] [Indexed: 02/06/2023]
Abstract
Patients with myotonic dystrophy type 1 (DM1) identify chronic fatigue as the most debilitating symptom, which manifests in part as prolonged recovery after exercise. Clinical features of DM1 result from pathogenic gain-of-function activity of transcripts containing an expanded microsatellite CUG repeat (CUGexp). In DM1 mice, therapies targeting the CUGexp transcripts correct the molecular phenotype, reverse myotonia, and improve muscle pathology. However, the effect of targeted molecular therapies on fatigue in DM1 is unknown. Here, we use two mouse models of DM1, age-matched wild-type controls, an exercise-activity assay, electrical impedance myography, and therapeutic antisense oligonucleotides (ASOs) to show that exaggerated exercise-induced fatigue progresses with age, is unrelated to muscle fiber size, and persists despite correction of the molecular phenotype for 3 months. In old DM1 mice, ASO treatment combined with an exercise training regimen consisting of treadmill walking 30 min per day 6 days per week for 3 months reverse all measures of fatigue. Exercise training without ASO therapy improves some measures of fatigue without correction of the molecular pathology. Our results highlight a key limitation of ASO monotherapy for this clinically important feature and support the development of moderate-intensity exercise as an adjuvant for targeted molecular therapies of DM1.
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Ballester-Lopez A, Koehorst E, Linares-Pardo I, Núñez-Manchón J, Almendrote M, Lucente G, Arbex A, Alonso CP, Lucia A, Monckton DG, Cumming SA, Pintos-Morell G, Coll-Cantí J, Ramos-Fransi A, Martínez-Piñeiro A, Nogales-Gadea G. Preliminary Findings on CTG Expansion Determination in Different Tissues from Patients with Myotonic Dystrophy Type 1. Genes (Basel) 2020; 11:genes11111321. [PMID: 33171734 PMCID: PMC7695006 DOI: 10.3390/genes11111321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 12/27/2022] Open
Abstract
Myotonic Dystrophy type 1 (DM1) is characterized by a high genetic and clinical variability. Determination of the genetic variability in DM1 might help to determine whether there is an association between CTG (Cytosine-Thymine-Guanine) expansion and the clinical manifestations of this condition. We studied the variability of the CTG expansion (progenitor, mode, and longest allele, respectively, and genetic instability) in three tissues (blood, muscle, and tissue) from eight patients with DM1. We also studied the association of genetic data with the patients’ clinical characteristics. Although genetic instability was confirmed in all the tissues that we studied, our results suggest that CTG expansion is larger in muscle and skin cells compared with peripheral blood leukocytes. While keeping in mind that more research is needed in larger cohorts, we have provided preliminary evidence suggesting that the estimated progenitor CTG size in muscle could be potentially used as an indicator of age of disease onset and muscle function impairment.
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Affiliation(s)
- Alfonsina Ballester-Lopez
- Neuromuscular and Neuropediatric Research Group, Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Barcelona, Spain; (A.B.-L.); (E.K.); (I.L.-P.); (J.N.-M.)
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain;
| | - Emma Koehorst
- Neuromuscular and Neuropediatric Research Group, Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Barcelona, Spain; (A.B.-L.); (E.K.); (I.L.-P.); (J.N.-M.)
| | - Ian Linares-Pardo
- Neuromuscular and Neuropediatric Research Group, Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Barcelona, Spain; (A.B.-L.); (E.K.); (I.L.-P.); (J.N.-M.)
| | - Judit Núñez-Manchón
- Neuromuscular and Neuropediatric Research Group, Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Barcelona, Spain; (A.B.-L.); (E.K.); (I.L.-P.); (J.N.-M.)
| | - Miriam Almendrote
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain; (M.A.); (G.L.); (A.A.); (J.C.-C.); (A.R.-F.); (A.M.-P.)
| | - Giuseppe Lucente
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain; (M.A.); (G.L.); (A.A.); (J.C.-C.); (A.R.-F.); (A.M.-P.)
| | - Andrea Arbex
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain; (M.A.); (G.L.); (A.A.); (J.C.-C.); (A.R.-F.); (A.M.-P.)
| | - Carles Puente Alonso
- Servei de Cirugia Ortopèdica i Traumatologia, Unitat de mà i nervi Perifèric, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain;
| | - Alejandro Lucia
- Facultad de Ciencias de la Actividad física y el Deporte, Universidad Europea, 28670 Madrid, Spain;
- Instituto de Investigación Hospital 12 de Octubre (i+12), 28041 Madrid, Spain
| | - Darren G. Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G126QQ, UK; (D.G.M.); (S.A.C.)
| | - Sarah A. Cumming
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G126QQ, UK; (D.G.M.); (S.A.C.)
| | - Guillem Pintos-Morell
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain;
- Division of Rare Diseases, Vall d’Hebron University Hospital, 08035 Barcelona, Spain
| | - Jaume Coll-Cantí
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain; (M.A.); (G.L.); (A.A.); (J.C.-C.); (A.R.-F.); (A.M.-P.)
| | - Alba Ramos-Fransi
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain; (M.A.); (G.L.); (A.A.); (J.C.-C.); (A.R.-F.); (A.M.-P.)
| | - Alicia Martínez-Piñeiro
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Barcelona, Spain; (M.A.); (G.L.); (A.A.); (J.C.-C.); (A.R.-F.); (A.M.-P.)
| | - Gisela Nogales-Gadea
- Neuromuscular and Neuropediatric Research Group, Institut d’Investigació en Ciències de la Salut Germans Trias i Pujol, Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Barcelona, Spain; (A.B.-L.); (E.K.); (I.L.-P.); (J.N.-M.)
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain;
- Correspondence: ; Tel.: +34-93-4978684
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An Overview of Alternative Splicing Defects Implicated in Myotonic Dystrophy Type I. Genes (Basel) 2020; 11:genes11091109. [PMID: 32971903 PMCID: PMC7564762 DOI: 10.3390/genes11091109] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/14/2020] [Accepted: 09/17/2020] [Indexed: 01/02/2023] Open
Abstract
Myotonic dystrophy type I (DM1) is the most common form of adult muscular dystrophy, caused by expansion of a CTG triplet repeat in the 3′ untranslated region (3′UTR) of the myotonic dystrophy protein kinase (DMPK) gene. The pathological CTG repeats result in protein trapping by expanded transcripts, a decreased DMPK translation and the disruption of the chromatin structure, affecting neighboring genes expression. The muscleblind-like (MBNL) and CUG-BP and ETR-3-like factors (CELF) are two families of tissue-specific regulators of developmentally programmed alternative splicing that act as antagonist regulators of several pre-mRNA targets, including troponin 2 (TNNT2), insulin receptor (INSR), chloride channel 1 (CLCN1) and MBNL2. Sequestration of MBNL proteins and up-regulation of CELF1 are key to DM1 pathology, inducing a spliceopathy that leads to a developmental remodelling of the transcriptome due to an adult-to-foetal splicing switch, which results in the loss of cell function and viability. Moreover, recent studies indicate that additional pathogenic mechanisms may also contribute to disease pathology, including a misregulation of cellular mRNA translation, localization and stability. This review focuses on the cause and effects of MBNL and CELF1 deregulation in DM1, describing the molecular mechanisms underlying alternative splicing misregulation for a deeper understanding of DM1 complexity. To contribute to this analysis, we have prepared a comprehensive list of transcript alterations involved in DM1 pathogenesis, as well as other deregulated mRNA processing pathways implications.
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32
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HDAC3 deacetylates the DNA mismatch repair factor MutSβ to stimulate triplet repeat expansions. Proc Natl Acad Sci U S A 2020; 117:23597-23605. [PMID: 32900932 PMCID: PMC7519323 DOI: 10.1073/pnas.2013223117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Trinucleotide repeat (TNR) expansions cause nearly 20 severe human neurological diseases which are currently untreatable. For some of these diseases, ongoing somatic expansions accelerate disease progression and may influence age of onset. This new knowledge emphasizes the importance of understanding the protein factors that drive expansions. Recent genetic evidence indicates that the mismatch repair factor MutSβ (Msh2-Msh3 complex) and the histone deacetylase HDAC3 function in the same pathway to drive triplet repeat expansions. Here we tested the hypothesis that HDAC3 deacetylates MutSβ and thereby activates it to drive expansions. The HDAC3-selective inhibitor RGFP966 was used to examine its biological and biochemical consequences in human tissue culture cells. HDAC3 inhibition efficiently suppresses repeat expansion without impeding canonical mismatch repair activity. Five key lysine residues in Msh3 are direct targets of HDAC3 deacetylation. In cells expressing Msh3 in which these lysine residues are mutated to arginine, the inhibitory effect of RGFP966 on expansions is largely bypassed, consistent with the direct deacetylation hypothesis. RGFP966 treatment does not alter MutSβ subunit abundance or complex formation but does partially control its subcellular localization. Deacetylation sites in Msh3 overlap a nuclear localization signal, and we show that localization of MutSβ is partially dependent on HDAC3 activity. Together, these results indicate that MutSβ is a key target of HDAC3 deacetylation and provide insights into an innovative regulatory mechanism for triplet repeat expansions. The results suggest expansion activity may be druggable and support HDAC3-selective inhibition as an attractive therapy in some triplet repeat expansion diseases.
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Hildonen M, Knak KL, Dunø M, Vissing J, Tümer Z. Stable Longitudinal Methylation Levels at the CpG Sites Flanking the CTG Repeat of DMPK in Patients with Myotonic Dystrophy Type 1. Genes (Basel) 2020; 11:genes11080936. [PMID: 32823742 PMCID: PMC7465187 DOI: 10.3390/genes11080936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/10/2020] [Accepted: 08/10/2020] [Indexed: 12/11/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystem disorder mainly characterized by gradual muscle loss, weakness, and delayed relaxation after muscle contraction. It is caused by an expanded CTG repeat in the 3′ UTR of DMPK, which is transcribed into a toxic gain-of-function mRNA that affects the splicing of a range of other genes. The repeat is unstable, with a bias towards expansions both in somatic cells and in the germline, which results in a tendency for earlier onset with each generation, as longer repeat lengths generally correlate with earlier onset. Previous studies have found hypermethylation in the regions flanking the repeat in congenital onset DM1 and in some patients with non-congenital DM1. We used pyrosequencing to investigate blood methylation levels in 68 patients with non-congenital DM1, compare the methylation levels between the blood and muscle, and assess whether methylation levels change over time in the blood. We found higher methylation levels in the blood of DM1 patients than in healthy controls and especially in the patients who had inherited the disease allele maternally. The methylation levels remained relatively stable over time and are a strong biomarker of the disease, as well as of the maternal inheritance of the disease.
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Affiliation(s)
- Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark;
| | - Kirsten Lykke Knak
- Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark; (K.L.K.); (J.V.)
| | - Morten Dunø
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - John Vissing
- Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark; (K.L.K.); (J.V.)
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark;
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence: ; Tel.: +45-2920-4855
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34
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Affiliation(s)
- Michael D Flower
- University College London (UCL) Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology and Dementia Research Centre at UCL, London, UK
| | - Sarah J Tabrizi
- University College London (UCL) Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology and Dementia Research Centre at UCL, London, UK.
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35
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Flower M, Lomeikaite V, Holmans P, Jones L, Tabrizi SJ, Monckton DG. Reply: The repeat variant in MSH3 is not a genetic modifier for spinocerebellar ataxia type 3 and Friedreich's ataxia. Brain 2020; 143:e26. [PMID: 32154840 DOI: 10.1093/brain/awaa044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Michael Flower
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Vilija Lomeikaite
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, UK
| | - Sarah J Tabrizi
- Department of Neurodegenerative Disease and Dementia Research Institute, UCL, UK
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, UK
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36
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Overend G, Légaré C, Mathieu J, Bouchard L, Gagnon C, Monckton DG. Allele length of the DMPK CTG repeat is a predictor of progressive myotonic dystrophy type 1 phenotypes. Hum Mol Genet 2020; 28:2245-2254. [PMID: 31220271 DOI: 10.1093/hmg/ddz055] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/13/2019] [Accepted: 03/13/2019] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant inherited disorder caused by expansion of a germline and somatically unstable CTG repeat in the DMPK gene. Previously, CTG repeat length at birth has been correlated to patient age at symptom onset. Attempts to correlate CTG repeat length with progressive DM1 phenotypes, such as muscle power, have proven difficult. To better correlate genotype with progressive phenotypes, we have measured CTG repeat tract length and screened for interrupting variant repeats in 192 study participants from a well-characterized Canadian cohort. We have assessed genotype-phenotype correlations with nine progressive measures of skeletal muscle power and respiratory function. We have built statistical models that include confounding factors such as sex, age, height and weight to further explain variation in muscle power. Our analysis reveals a strong correlation between DM1 genotype and respiratory function and skeletal muscle power, as part of a complex model that includes additional modulators such as sex, age, height, weight and the presence or absence of interrupting variant repeats. Distal skeletal muscle measurements, such as hand pinch and grip strength, show the strongest correlation with disease genotype. Detailed analysis of CTG repeat length, and incorporation of confounding factors, greatly improves the predictive ability of these models. They reveal a greater genetic influence on individual progressive phenotypes than on age at symptom onset and for clinical trials will help optimize stratification and explain patient variability. They will also help practitioners prioritize assessment of the muscular power measurements that correlate best with disease severity.
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Affiliation(s)
- Gayle Overend
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Cécilia Légaré
- Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Québec, Canada.,ECOGENE Biocluster, Chicoutimi, Québec, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires, Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, rue de l'Hôpital, Saguenay, Québec, Canada
| | - Jean Mathieu
- École de réadaptation, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires, Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, rue de l'Hôpital, Saguenay, Québec, Canada
| | - Luigi Bouchard
- Department of Biochemistry, Université de Sherbrooke, Sherbrooke, Québec, Canada.,ECOGENE Biocluster, Chicoutimi, Québec, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires, Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, rue de l'Hôpital, Saguenay, Québec, Canada
| | - Cynthia Gagnon
- École de réadaptation, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires, Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, rue de l'Hôpital, Saguenay, Québec, Canada
| | - Darren G Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Serra L, Bianchi G, Bruschini M, Giulietti G, Domenico CD, Bonarota S, Petrucci A, Silvestri G, Perna A, Meola G, Caltagirone C, Bozzali M. Abnormal Cortical Thickness Is Associated With Deficits in Social Cognition in Patients With Myotonic Dystrophy Type 1. Front Neurol 2020; 11:113. [PMID: 32180756 PMCID: PMC7059122 DOI: 10.3389/fneur.2020.00113] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/31/2020] [Indexed: 12/15/2022] Open
Abstract
Aim: To investigate the cortical thickness in myotonic dystrophy type 1 (DM1) and its potential association with patients' genetic triplet expansion and social cognition deficits. Methods: Thirty patients with DM1 underwent the Social Cognition Battery Test and magnetic resonance imaging (MRI) scanning at 3 T. Twenty-five healthy subjects (HSs) were enrolled in the study to serve as a control group for structural MRI data. To assess changes in cortical thickness in DM1 patients, they were compared to HSs using a t-test model. Correlations were used to assess potential associations between genetic and clinical characteristics and social cognition performances in the patient group. Additionally, multiple regression models were used to explore associations between cortical thickness, CTG triplet expansion size, and scores obtained by DM1 patients on the Social Cognition Battery. Results: DM1 patients showed low performances in several subtests of the Social Cognition Battery. Specifically, they obtained pathological scores at Emotion Attribution Test (i.e., Sadness, Embarrassment, Happiness, and Anger) and at the Social Situations Test (i.e., recognition of normal situation, recognition of aberrant behavior). Significant negative correlations were found between CTG triplet expansion size and Embarrassment, and Severity of Aberrant Behavior. Similarly, a negative correlation was found between patients' MIRS scores and Sadness. DM1 patients compared to HSs showed reduced thickness in the right premotor cortex, angular gyrus, precuneus, and inferior parietal lobule. Significant associations were found between patients' CTG triplet expansion size and thickness in left postcentral gyrus and in the left primary somatosensory cortex, in the posterior cingulate cortex bilaterally, and in the right lingual gyrus. Finally, significant associations were found between cortical thickness and sadness in the superior temporal gyrus, the right precentral gyrus, the right angular gyrus, and the left medial frontal gyrus bilaterally. DM1 patients showed a negative correlation between cortical thickness in the bilateral precuneus and in the left lateral occipital cortex and performance at the Social Situations Test. Finally, DM1 patients showed a negative correlation between cortical thickness in the left precuneus and in the superior frontal gyrus and scores at the Moral Distinction Test. Discussion: The present study shows both cortical thickness changes in DM1 patients compared to controls and significant associations between cortical thickness and patients' social cognition performances. These data confirm the presence of widespread brain damages associated with cognitive impairment in DM1 patients.
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Affiliation(s)
- Laura Serra
- Neuroimaging Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy
| | | | | | | | | | - Sabrina Bonarota
- Neuroimaging Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Antonio Petrucci
- UOC Neurologia e Neurofisiopatologia, AO San Camillo Forlanini, Rome, Italy
| | - Gabriella Silvestri
- Department of Geriatrics, Orthopedic and Neuroscience, Institute of Neurology, Catholic University of Sacred Heart, Rome, Italy
| | - Alessia Perna
- Department of Geriatrics, Orthopedic and Neuroscience, Institute of Neurology, Catholic University of Sacred Heart, Rome, Italy
| | - Giovanni Meola
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
| | - Carlo Caltagirone
- Department of Clinical and Behavioral Neurology, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Marco Bozzali
- Neuroimaging Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy.,Brighton & Sussex Medical School, CISC, University of Sussex, Brighton, United Kingdom
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Nutter CA, Bubenik JL, Oliveira R, Ivankovic F, Sznajder ŁJ, Kidd BM, Pinto BS, Otero BA, Carter HA, Vitriol EA, Wang ET, Swanson MS. Cell-type-specific dysregulation of RNA alternative splicing in short tandem repeat mouse knockin models of myotonic dystrophy. Genes Dev 2019; 33:1635-1640. [PMID: 31624084 PMCID: PMC6942047 DOI: 10.1101/gad.328963.119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/24/2019] [Indexed: 11/25/2022]
Abstract
Short tandem repeats (STRs) are prone to expansion mutations that cause multiple hereditary neurological and neuromuscular diseases. To study pathomechanisms using mouse models that recapitulate the tissue specificity and developmental timing of an STR expansion gene, we used rolling circle amplification and CRISPR/Cas9-mediated genome editing to generate Dmpk CTG expansion (CTGexp) knockin models of myotonic dystrophy type 1 (DM1). We demonstrate that skeletal muscle myoblasts and brain choroid plexus epithelial cells are particularly susceptible to Dmpk CTGexp mutations and RNA missplicing. Our results implicate dysregulation of muscle regeneration and cerebrospinal fluid homeostasis as early pathogenic events in DM1.
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Affiliation(s)
- Curtis A Nutter
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Jodi L Bubenik
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Ruan Oliveira
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Franjo Ivankovic
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Łukasz J Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Benjamin M Kidd
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Belinda S Pinto
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Brittney A Otero
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Helmut A Carter
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Eric A Vitriol
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida 32610, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
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A CTG repeat-selective chemical screen identifies microtubule inhibitors as selective modulators of toxic CUG RNA levels. Proc Natl Acad Sci U S A 2019; 116:20991-21000. [PMID: 31570586 DOI: 10.1073/pnas.1901893116] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A CTG repeat expansion in the DMPK gene is the causative mutation of myotonic dystrophy type 1 (DM1). Transcription of the expanded CTG repeat produces toxic gain-of-function CUG RNA, leading to disease symptoms. A screening platform that targets production or stability of the toxic CUG RNA in a selective manner has the potential to provide new biological and therapeutic insights. A DM1 HeLa cell model was generated that stably expresses a toxic r(CUG)480 and an analogous r(CUG)0 control from DMPK and was used to measure the ratio-metric level of r(CUG)480 versus r(CUG)0. This DM1 HeLa model recapitulates pathogenic hallmarks of DM1, including CUG ribonuclear foci and missplicing of pre-mRNA targets of the muscleblind (MBNL) alternative splicing factors. Repeat-selective screening using this cell line led to the unexpected identification of multiple microtubule inhibitors as hits that selectively reduce r(CUG)480 levels and partially rescue MBNL-dependent missplicing. These results were validated by using the Food and Drug Administration-approved clinical microtubule inhibitor colchicine in DM1 mouse and primary patient cell models. The mechanism of action was found to involve selective reduced transcription of the CTG expansion that we hypothesize to involve the LINC (linker of nucleoskeleton and cytoskeleton) complex. The unanticipated identification of microtubule inhibitors as selective modulators of toxic CUG RNA opens research directions for this form of muscular dystrophy and may shed light on the biology of CTG repeat expansion and inform therapeutic avenues. This approach has the potential to identify modulators of expanded repeat-containing gene expression for over 30 microsatellite expansion disorders.
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Cumming SA, Jimenez-Moreno C, Okkersen K, Wenninger S, Daidj F, Hogarth F, Littleford R, Gorman G, Bassez G, Schoser B, Lochmüller H, van Engelen BGM, Monckton DG. Genetic determinants of disease severity in the myotonic dystrophy type 1 OPTIMISTIC cohort. Neurology 2019; 93:e995-e1009. [PMID: 31395669 PMCID: PMC6745735 DOI: 10.1212/wnl.0000000000008056] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 04/10/2019] [Indexed: 01/11/2023] Open
Abstract
Objective To evaluate the role of genetic variation at the DMPK locus on symptomatic diversity in 250 adult, ambulant patients with myotonic dystrophy type 1 (DM1) recruited to the Observational Prolonged Trial in Myotonic Dystrophy Type 1 to Improve Quality of Life—Standards, a Target Identification Collaboration (OPTIMISTIC) clinical trial. Methods We used small pool PCR to correct age at sampling biases and estimate the progenitor allele CTG repeat length and somatic mutational dynamics, and AciI digests and repeat primed PCR to test for the presence of variant repeats. Results We confirmed disease severity is driven by progenitor allele length, is further modified by age, and, in some cases, sex, and that patients in whom the CTG repeat expands more rapidly in the soma develop symptoms earlier than predicted. We revealed a key role for variant repeats in reducing disease severity and quantified their role in delaying age at onset by approximately 13.2 years (95% confidence interval 5.7–20.7, 2-tailed t test t = −3.7, p = 0.0019). Conclusions Careful characterization of the DMPK CTG repeat to define progenitor allele length and presence of variant repeats has increased utility in understanding clinical variability in a trial cohort and provides a genetic route for defining disease-specific outcome measures, and the basis of treatment response and stratification in DM1 trials.
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Affiliation(s)
- Sarah A Cumming
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Cecilia Jimenez-Moreno
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Kees Okkersen
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Stephan Wenninger
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Ferroudja Daidj
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Fiona Hogarth
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Roberta Littleford
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Gráinne Gorman
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Guillaume Bassez
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Benedikt Schoser
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Hanns Lochmüller
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Baziel G M van Engelen
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK
| | - Darren G Monckton
- From the Institute of Molecular, Cell and Systems Biology (S.A.C., D.G.M.), University of Glasgow; Institute of Genetic Medicine (C.J.-M., H.L.) and Institute of Neurosciences (G.G.), Newcastle University, Newcastle upon Tyne, UK; Department of Neurology (K.O., B.G.M.v.E.), Donders Institute for Brain Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands; Department of Neurology (S.W., B.S.), Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany; Neuromuscular Reference Centre (F.D., G.B.), Assistance Publique-Hôpitaux de Paris, France; and Tayside Clinical Trials Unit (F.H., R.L.), The University of Dundee, UK.
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Lanni S, Pearson CE. Molecular genetics of congenital myotonic dystrophy. Neurobiol Dis 2019; 132:104533. [PMID: 31326502 DOI: 10.1016/j.nbd.2019.104533] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/29/2019] [Accepted: 07/11/2019] [Indexed: 12/26/2022] Open
Abstract
Myotonic Dystrophy type 1 (DM1) is a neuromuscular disease showing strong genetic anticipation, and is caused by the expansion of a CTG repeat tract in the 3'-UTR of the DMPK gene. Congenital Myotonic Dystrophy (CDM1) represents the most severe form of the disease, with prenatal onset, symptoms distinct from adult onset DM1, and a high rate of perinatal mortality. CDM1 is usually associated with very large CTG expansions, but this correlation is not absolute and cannot explain the distinct clinical features and the strong bias for maternal transmission. This review focuses upon the molecular and epigenetic factors that modulate disease severity and might be responsible for CDM1. Changes in the epigenetic status of the DM1 locus and in gene expression have recently been observed. Increasing evidence supports a role of a CTCF binding motif as a cis-element, upstream of the DMPK CTG tract, whereby CpG methylation of this site regulates the interaction of the insulator protein CTCF as a modulating trans-factor responsible for the inheritance and expression of CDM1.
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Affiliation(s)
- Stella Lanni
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto M5G 0A4, Ontario, Canada
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto M5G 0A4, Ontario, Canada; University of Toronto, Program of Molecular Genetics, Canada.
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Sznajder ŁJ, Swanson MS. Short Tandem Repeat Expansions and RNA-Mediated Pathogenesis in Myotonic Dystrophy. Int J Mol Sci 2019; 20:ijms20133365. [PMID: 31323950 PMCID: PMC6651174 DOI: 10.3390/ijms20133365] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 06/27/2019] [Accepted: 07/08/2019] [Indexed: 12/23/2022] Open
Abstract
Short tandem repeat (STR) or microsatellite, expansions underlie more than 50 hereditary neurological, neuromuscular and other diseases, including myotonic dystrophy types 1 (DM1) and 2 (DM2). Current disease models for DM1 and DM2 propose a common pathomechanism, whereby the transcription of mutant DMPK (DM1) and CNBP (DM2) genes results in the synthesis of CUG and CCUG repeat expansion (CUGexp, CCUGexp) RNAs, respectively. These CUGexp and CCUGexp RNAs are toxic since they promote the assembly of ribonucleoprotein (RNP) complexes or RNA foci, leading to sequestration of Muscleblind-like (MBNL) proteins in the nucleus and global dysregulation of the processing, localization and stability of MBNL target RNAs. STR expansion RNAs also form phase-separated gel-like droplets both in vitro and in transiently transfected cells, implicating RNA-RNA multivalent interactions as drivers of RNA foci formation. Importantly, the nucleation and growth of these nuclear foci and transcript misprocessing are reversible processes and thus amenable to therapeutic intervention. In this review, we provide an overview of potential DM1 and DM2 pathomechanisms, followed by a discussion of MBNL functions in RNA processing and how multivalent interactions between expanded STR RNAs and RNA-binding proteins (RBPs) promote RNA foci assembly.
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Affiliation(s)
- Łukasz J Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA.
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
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Carrell ST, Tang Z, Mohr S, Lambowitz AM, Thornton CA. Detection of expanded RNA repeats using thermostable group II intron reverse transcriptase. Nucleic Acids Res 2019; 46:e1. [PMID: 29036654 PMCID: PMC5758912 DOI: 10.1093/nar/gkx867] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/27/2017] [Indexed: 12/15/2022] Open
Abstract
Cellular accumulation of repetitive RNA occurs in several dominantly-inherited genetic disorders. Expanded CUG, CCUG or GGGGCC repeats are expressed in myotonic dystrophy type 1 (DM1), myotonic dystrophy type 2 (DM2), or familial amyotrophic lateral sclerosis, respectively. Expanded repeat RNAs (ER-RNAs) exert a toxic gain-of-function and are prime therapeutic targets in these diseases. However, efforts to quantify ER-RNA levels or monitor knockdown are confounded by stable structure and heterogeneity of the ER-RNA tract and background signal from non-expanded repeats. Here, we used a thermostable group II intron reverse transcriptase (TGIRT-III) to convert ER-RNA to cDNA, followed by quantification on slot blots. We found that TGIRT-III was capable of reverse transcription (RTn) on enzymatically synthesized ER-RNAs. By using conditions that limit cDNA synthesis from off-target sequences, we observed hybridization signals on cDNA slot blots from DM1 and DM2 muscle samples but not from healthy controls. In transgenic mouse models of DM1 the cDNA slot blots accurately reflected the differences of ER-RNA expression across different transgenic lines, and showed therapeutic reductions in skeletal and cardiac muscle, accompanied by improvements of the DM1-associated splicing defects. TGIRT-III was also active on CCCCGG- and GGGGCC-repeats, suggesting that ER-RNA analysis is feasible for several repeat expansion disorders.
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Affiliation(s)
- Samuel T Carrell
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY 14611, USA
| | - Zhenzhi Tang
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14611, USA
| | - Sabine Mohr
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Alan M Lambowitz
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Charles A Thornton
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14611, USA
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Wahbi K, Furling D. Cardiovascular manifestations of myotonic dystrophy. Trends Cardiovasc Med 2019; 30:232-238. [PMID: 31213350 DOI: 10.1016/j.tcm.2019.06.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 06/03/2019] [Accepted: 06/04/2019] [Indexed: 11/25/2022]
Abstract
Patients with myotonic dystrophy, the most common neuromuscular dystrophy in adults, have a high prevalence of arrhythmic complications with increased cardiovascular mortality and high risk for sudden death. Sudden death prevention is central and relies on annual follow-up and prophylactic permanent pacing in patients with conduction defects on electrocardiogram and/or infrahisian blocks on electrophysiological study. Implantable cardiac defibrillator therapy may be indicated in patients with ventricular tachyarrhythmia.
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Affiliation(s)
- Karim Wahbi
- APHP, Cochin Hospital, Cardiology Department, Centre de Référence de Pathologie Neuromusculaire, Nord Est, Ile de France, Paris-Descartes, Sorbonne Paris Cité University, Cochin Hospital, 27 Rue du Faubourg Saint Jacques, 75679 Paris Cedex 14 Paris, France.
| | - Denis Furling
- Sorbonne Université, INSERM, Association Institut de Myologie, Centre de Recherche en Myologie, Paris, France
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Analysis of mutational dynamics at the DMPK (CTG)n locus identifies saliva as a suitable DNA sample source for genetic analysis in myotonic dystrophy type 1. PLoS One 2019; 14:e0216407. [PMID: 31048891 PMCID: PMC6497304 DOI: 10.1371/journal.pone.0216407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 04/21/2019] [Indexed: 12/12/2022] Open
Abstract
Genotype-to-phenotype correlation studies in myotonic dystrophy type 1 (DM1) have been confounded by the age-dependent, tissue-specific and expansion-biased features of somatic mosaicism of the expanded CTG repeat. Previously, we showed that by controlling for the confounding effects of somatic instability to estimate the progenitor allele CTG length in blood DNA, age at onset correlations could be significantly improved. To determine the suitability of saliva DNA as a source for genotyping, we used small pool-PCR to perform a detailed quantitative study of the somatic mutational dynamics of the CTG repeat in saliva and blood DNA from 40 DM1 patients. Notably, the modal allele length in saliva was only moderately higher in saliva and not as large as previously observed in most other tissues. The lower boundary of the allele distribution was also slightly higher in saliva than it was in blood DNA. However, the progenitor allele length estimated in blood explained more of the variation in age at onset than that estimated from saliva. Interestingly, although the modal allele length was slightly higher in saliva, the overall degree of somatic variation was typically lower than in blood DNA, revealing new insights into the tissue-specific dynamics of somatic mosaicism. These data indicate that saliva constitutes an accessible, non-invasive and suitable DNA sample source for performing genetic studies in DM1.
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Winkler NS, Milone M, Martinez-Thompson JM, Raja H, Aleff RA, Patel SV, Fautsch MP, Wieben ED, Baratz KH. Fuchs' Endothelial Corneal Dystrophy in Patients With Myotonic Dystrophy, Type 1. Invest Ophthalmol Vis Sci 2019; 59:3053-3057. [PMID: 30025114 PMCID: PMC6005624 DOI: 10.1167/iovs.17-23160] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose RNA toxicity from CTG trinucleotide repeat (TNR) expansion within noncoding DNA of the transcription factor 4 (TCF4) and DM1 protein kinase (DMPK) genes has been described in Fuchs' endothelial corneal dystrophy (FECD) and myotonic dystrophy, type 1 (DM1), respectively. We prospectively evaluated DM1 patients and their families for phenotypic FECD and report the analysis of CTG expansion in the TCF4 gene and DMPK expression in corneal endothelium. Methods FECD grade was evaluated by slit lamp biomicroscopy in 26 participants from 14 families with DM1. CTG TNR length in TCF4 and DMPK was determined by a combination of Gene Scan and Southern blotting of peripheral blood leukocyte DNA. Results FECD grade was 2 or higher in 5 (36%) of 14 probands, significantly greater than the general population (5%) (P < 0.001). FECD segregated with DM1; six of eight members of the largest family had both FECD and DM1, while the other two family members had neither disease. All DNA samples from 24 subjects, including four FECD-affected probands, were bi-allelic for nonexpanded TNR length in TCF4 (<40 repeats). Considering a 75% prevalence of TCF4 TNR expansion in FECD, the probability of four FECD probands lacking TNR expansion was 0.4%. Neither severity of DM1 nor DMPK TNR length predicted the presence of FECD in DM1 patients. Conclusions FECD was common in DM1 families, and the diseases cosegregated. TCF4 TNR expansion was lacking in DM1 families. These findings support a hypothesis that DMPK TNR expansion contributes to clinical FECD.
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Affiliation(s)
- Nelson S Winkler
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Margherita Milone
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, United States
| | | | - Harish Raja
- Mount Sinai School of Medicine, New York, New York, United States
| | - Ross A Aleff
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States
| | - Sanjay V Patel
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Eric D Wieben
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States
| | - Keith H Baratz
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
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Souidi A, Zmojdzian M, Jagla K. Dissecting Pathogenetic Mechanisms and Therapeutic Strategies in Drosophila Models of Myotonic Dystrophy Type 1. Int J Mol Sci 2018; 19:E4104. [PMID: 30567354 PMCID: PMC6321436 DOI: 10.3390/ijms19124104] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 12/08/2018] [Accepted: 12/13/2018] [Indexed: 12/16/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1), the most common cause of adult-onset muscular dystrophy, is autosomal dominant, multisystemic disease with characteristic symptoms including myotonia, heart defects, cataracts and testicular atrophy. DM1 disease is being successfully modelled in Drosophila allowing to identify and validate new pathogenic mechanisms and potential therapeutic strategies. Here we provide an overview of insights gained from fruit fly DM1 models, either: (i) fundamental with particular focus on newly identified gene deregulations and their link with DM1 symptoms; or (ii) applied via genetic modifiers and drug screens to identify promising therapeutic targets.
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Affiliation(s)
- Anissa Souidi
- GReD, INSERM U1103, CNRS, UMR6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France.
| | - Monika Zmojdzian
- GReD, INSERM U1103, CNRS, UMR6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France.
| | - Krzysztof Jagla
- GReD, INSERM U1103, CNRS, UMR6293, University of Clermont Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France.
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Validation of the Nine Hole Peg Test as a measure of dexterity in myotonic dystrophy type 1. Neuromuscul Disord 2018; 28:947-951. [PMID: 30270126 DOI: 10.1016/j.nmd.2018.08.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/24/2018] [Accepted: 08/28/2018] [Indexed: 11/17/2022]
Abstract
We aimed to validate the Nine Hole Peg Test as a measure of dexterity in myotonic dystrophy type 1 (DM1). Fifty patients with adult-onset, genetically confirmed DM1 were evaluated by Nine Hole Peg Test and re-evaluated at one week. Myotonia was not a limiting factor. The first test was compared with that performed by normal subjects (n = 28). Contextually, patients underwent handgrip and three-finger pinch assessments by handheld dynamometer. The Nine Hole Peg Test showed high intra-rater and inter-rater reliability in DM1 [ICC 0.86/0.83 for dominant and 0.90/0.88 for non-dominant hand, respectively]. Inverse correlation with handgrip and pinch strength values (r = -0.4; p < 0.01) and direct correlation with Muscular Impairment Rating Scale (r = 0.4; p < 0.01) were found for both DH and NDH. The test was able to differentiate severe DM1 patients, stratified by extent of muscle impairment, from mildly affected and normal controls, with a sensitivity of 97% and 95% for dominant hand and non-dominant hand, respectively (p < 0.0001). In conclusion, we showed that the Nine Hole Peg Test is a reliable, valid and sensitive test of dexterity in DM1, and that it can be considered as a candidate outcome measure to monitor natural history of disease and, possibly, therapeutic response in clinical trials.
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Abstract
Myotonic dystrophy is an autosomal dominant muscular dystrophy not only associated with muscle weakness, atrophy, and myotonia but also prominent multisystem involvement. There are 2 similar, but distinct, forms of myotonic dystrophy; type 1 is caused by a CTG repeat expansion in the DMPK gene, and type 2 is caused by a CCTG repeat expansion in the CNBP gene. Type 1 is associated with distal limb, neck flexor, and bulbar weakness and results in different phenotypic subtypes with variable onset from congenital to very late-onset as well as variable signs and symptoms. The classically described adult-onset form is the most common. In contrast, myotonic dystrophy type 2 is adult-onset or late-onset, has proximal predominant muscle weakness, and generally has less severe multisystem involvement. In both forms of myotonic dystrophy, the best characterized disease mechanism is a RNA toxic gain-of-function during which RNA repeats form nuclear foci resulting in sequestration of RNA-binding proteins and, therefore, dysregulated splicing of premessenger RNA. There are currently no disease-modifying therapies, but clinical surveillance, preventative measures, and supportive treatments are used to reduce the impact of muscular impairment and other systemic involvement including cataracts, cardiac conduction abnormalities, fatigue, central nervous system dysfunction, respiratory weakness, dysphagia, and endocrine dysfunction. Exciting preclinical progress has been made in identifying a number of potential strategies including genome editing, small molecule therapeutics, and antisense oligonucleotide-based therapies to target the pathogenesis of type 1 and type 2 myotonic dystrophies at the DNA, RNA, or downstream target level.
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Affiliation(s)
- Samantha LoRusso
- Department of Neurology, The Ohio State University, 395 West 12th Avenue, Columbus, OH, 43210, USA
| | - Benjamin Weiner
- The Ohio State University College of Medicine, The Ohio State University, 370 West 9th Avenue, Columbus, OH, 43210, USA
| | - W David Arnold
- Department of Neurology, The Ohio State University, 395 West 12th Avenue, Columbus, OH, 43210, USA.
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Kumari R, Kumar D, Brahmachari SK, Srivastava AK, Faruq M, Mukerji M. Paradigm for disease deconvolution in rare neurodegenerative disorders in Indian population: insights from studies in cerebellar ataxias. J Genet 2018. [DOI: 10.1007/s12041-018-0948-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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