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Núñez-Manchón J, Capó J, Martínez-Piñeiro A, Juanola E, Pesovic J, Mosqueira-Martín L, González-Imaz K, Maestre-Mora P, Odria R, Savic-Pavicevic D, Vallejo-Illarramendi A, Mamchaoui K, Bigot A, Mouly V, Suelves M, Nogales-Gadea G. Immortalized human myotonic dystrophy type 1 muscle cell lines to address patient heterogeneity. iScience 2024; 27:109930. [PMID: 38832025 PMCID: PMC11144749 DOI: 10.1016/j.isci.2024.109930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 03/21/2024] [Accepted: 05/03/2024] [Indexed: 06/05/2024] Open
Abstract
Historically, cellular models have been used as a tool to study myotonic dystrophy type 1 (DM1) and the validation of therapies in said pathology. However, there is a need for in vitro models that represent the clinical heterogeneity observed in patients with DM1 that is lacking in classical models. In this study, we immortalized three DM1 muscle lines derived from patients with different DM1 subtypes and clinical backgrounds and characterized them at the genetic, epigenetic, and molecular levels. All three cell lines display DM1 hallmarks, such as the accumulation of RNA foci, MBNL1 sequestration, splicing alterations, and reduced fusion. In addition, alterations in early myogenic markers, myotube diameter and CTCF1 DNA methylation were also found in DM1 cells. Notably, the new lines show a high level of heterogeneity in both the size of the CTG expansion and the aforementioned molecular alterations. Importantly, these immortalized cells also responded to previously tested therapeutics. Altogether, our results show that these three human DM1 cellular models are suitable to study the pathophysiological heterogeneity of DM1 and to test future therapeutic options.
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Affiliation(s)
- Judit Núñez-Manchón
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Júlia Capó
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Alicia Martínez-Piñeiro
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Eduard Juanola
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Jovan Pesovic
- University of Belgrade - Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Laura Mosqueira-Martín
- Group of Neurosciences, Department of Pediatrics, UPV/EHU, Hospital Universitario Donostia - IIS Biodonostia, 20014 San Sebastian, Spain
| | - Klaudia González-Imaz
- Group of Neurosciences, Department of Pediatrics, UPV/EHU, Hospital Universitario Donostia - IIS Biodonostia, 20014 San Sebastian, Spain
| | - Pau Maestre-Mora
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Renato Odria
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Dusanka Savic-Pavicevic
- University of Belgrade - Faculty of Biology, Center for Human Molecular Genetics, Belgrade, Serbia
| | - Ainara Vallejo-Illarramendi
- Group of Neurosciences, Department of Pediatrics, UPV/EHU, Hospital Universitario Donostia - IIS Biodonostia, 20014 San Sebastian, Spain
| | - Kamel Mamchaoui
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013 Paris, France
| | - Anne Bigot
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013 Paris, France
| | - Vincent Mouly
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013 Paris, France
| | - Mònica Suelves
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Gisela Nogales-Gadea
- Grup de REcerca Neuromuscular de BAdalona (GRENBA), Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
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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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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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Rapid and comprehensive diagnostic method for repeat expansion diseases using nanopore sequencing. NPJ Genom Med 2022; 7:62. [PMID: 36289212 PMCID: PMC9606279 DOI: 10.1038/s41525-022-00331-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 09/30/2022] [Indexed: 11/23/2022] Open
Abstract
We developed a diagnostic method for repeat expansion diseases using a long-read sequencer to improve currently available, low throughput diagnostic methods. We employed the real-time target enrichment system of the nanopore GridION sequencer using the adaptive sampling option, in which software-based target assignment is available without prior sample enrichment, and built an analysis pipeline that prioritized the disease-causing loci. Twenty-two patients with various neurological and neuromuscular diseases, including 12 with genetically diagnosed repeat expansion diseases and 10 manifesting cerebellar ataxia, but without genetic diagnosis, were analyzed. We first sequenced the 12 molecularly diagnosed patients and accurately confirmed expanded repeats in all with uniform depth of coverage across the loci. Next, we applied our method and a conventional method to 10 molecularly undiagnosed patients. Our method corrected inaccurate diagnoses of two patients by the conventional method. Our method is superior to conventional diagnostic methods in terms of speed, accuracy, and comprehensiveness.
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Koehorst E, Odria R, Capó J, Núñez-Manchón J, Arbex A, Almendrote M, Linares-Pardo I, Natera-de Benito D, Saez V, Nascimento A, Ortez C, Rubio MÁ, Díaz-Manera J, Alonso-Pérez J, Lucente G, Rodriguez-Palmero A, Ramos-Fransi A, Martínez-Piñeiro A, Nogales-Gadea G, Suelves M. An Integrative Analysis of DNA Methylation Pattern in Myotonic Dystrophy Type 1 Samples Reveals a Distinct DNA Methylation Profile between Tissues and a Novel Muscle-Associated Epigenetic Dysregulation. Biomedicines 2022; 10:biomedicines10061372. [PMID: 35740394 PMCID: PMC9220235 DOI: 10.3390/biomedicines10061372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/31/2022] [Accepted: 06/07/2022] [Indexed: 11/16/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a progressive, non-treatable, multi-systemic disorder. To investigate the contribution of epigenetics to the complexity of DM1, we compared DNA methylation profiles of four annotated CpG islands (CpGis) in the DMPK locus and neighbouring genes, in distinct DM1 tissues and derived cells, representing six DM1 subtypes, by bisulphite sequencing. In blood, we found no differences in CpGi 74, 43 and 36 in DNA methylation profile. In contrast, a CTCF1 DNA methylation gradient was found with 100% methylation in congenital cases, 50% in childhood cases and 13% in juvenile cases. CTCF1 methylation correlated to disease severity and CTG expansion size. Notably, 50% of CTCF1 methylated cases showed methylation in the CTCF2 regions. Additionally, methylation was associated with maternal transmission. Interestingly, the evaluation of seven families showed that unmethylated mothers passed on an expansion of the CTG repeat, whereas the methylated mothers transmitted a contraction. The analysis of patient-derived cells showed that DNA methylation profiles were highly preserved, validating their use as faithful DM1 cellular models. Importantly, the comparison of DNA methylation levels of distinct DM1 tissues revealed a novel muscle-specific epigenetic signature with methylation of the CTCF1 region accompanied by demethylation of CpGi 43, a region containing an alternative DMPK promoter, which may decrease the canonical promoter activity. Altogether, our results showed a distinct DNA methylation profile across DM1 tissues and uncovered a novel and dual epigenetic signature in DM1 muscle samples, providing novel insights into the epigenetic changes associated with DM1.
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Affiliation(s)
- Emma Koehorst
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Renato Odria
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Júlia Capó
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Judit Núñez-Manchón
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Andrea Arbex
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Miriam Almendrote
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Ian Linares-Pardo
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Daniel Natera-de Benito
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Verónica Saez
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Andrés Nascimento
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Carlos Ortez
- Neuromuscular Unit, Neuropediatric Department, Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, L'Hospitalet de Llobregat, 08950 Barcelona, Spain
| | - Miguel Ángel Rubio
- Neuromuscular Unit, Department of Neurology, Hospital del Mar, 08003 Barcelona, Spain
| | - Jordi Díaz-Manera
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
- John Walton Muscular Dystrophy Research Centre, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 3BZ, UK
| | - Jorge Alonso-Pérez
- Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
| | - Giuseppe Lucente
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Agustín Rodriguez-Palmero
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Pediatric Neurology Unit, Department of Pediatrics, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Alba Ramos-Fransi
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Alicia Martínez-Piñeiro
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- Neuromuscular Pathology Unit, Neurology Service, Neuroscience Department, Hospital Universitari Germans Trias i Pujol, 08916 Badalona, Spain
| | - Gisela Nogales-Gadea
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Mònica Suelves
- Neuromuscular and Neuropediatric Research Group, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Campus Can Ruti, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
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Rasmussen A, Hildonen M, Vissing J, Duno M, Tümer Z, Birkedal U. High Resolution Analysis of DMPK Hypermethylation and Repeat Interruptions in Myotonic Dystrophy Type 1. Genes (Basel) 2022; 13:genes13060970. [PMID: 35741732 PMCID: PMC9222588 DOI: 10.3390/genes13060970] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/19/2022] [Accepted: 05/26/2022] [Indexed: 02/05/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic neuromuscular disorder caused by the expansion of a CTG repeat in the 3′-UTR of DMPK, which is transcribed to a toxic gain-of-function RNA that affects splicing of a range of genes. The expanded repeat is unstable in both germline and somatic cells. The variable age at disease onset and severity of symptoms have been linked to the inherited CTG repeat length, non-CTG interruptions, and methylation levels flanking the repeat. In general, the genetic biomarkers are investigated separately with specific methods, making it tedious to obtain an overall characterisation of the repeat for a given individual. In the present study, we employed Oxford nanopore sequencing in a pilot study to simultaneously determine the repeat lengths, investigate the presence and nature of repeat interruptions, and quantify methylation levels in the regions flanking the CTG-repeats in four patients with DM1. We determined the repeat lengths, and in three patients, we observed interruptions which were not detected using repeat-primed PCR. Interruptions may thus be more common than previously anticipated and should be investigated in larger cohorts. Allele-specific analyses enabled characterisation of aberrant methylation levels specific to the expanded allele, which greatly increased the sensitivity and resolved cases where the methylation levels were ambiguous.
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Affiliation(s)
- Astrid Rasmussen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
| | - Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence:
| | - Ulf Birkedal
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
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de Pontual L, Tomé S. Overview of the Complex Relationship between Epigenetics Markers, CTG Repeat Instability and Symptoms in Myotonic Dystrophy Type 1. Int J Mol Sci 2022; 23:ijms23073477. [PMID: 35408837 PMCID: PMC8998570 DOI: 10.3390/ijms23073477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 02/05/2023] Open
Abstract
Among the trinucleotide repeat disorders, myotonic dystrophy type 1 (DM1) is one of the most complex neuromuscular diseases caused by an unstable CTG repeat expansion in the DMPK gene. DM1 patients exhibit high variability in the dynamics of CTG repeat instability and in the manifestations and progression of the disease. The largest expanded alleles are generally associated with the earliest and most severe clinical form. However, CTG repeat length alone is not sufficient to predict disease severity and progression, suggesting the involvement of other factors. Several data support the role of epigenetic alterations in clinical and genetic variability. By highlighting epigenetic alterations in DM1, this review provides a new avenue on how these changes can serve as biomarkers to predict clinical features and the mutation behavior.
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Affiliation(s)
| | - Stéphanie Tomé
- Correspondence: ; Tel.: +33-1-42-16-57-16; Fax: +33-1-42-16-57-00
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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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De Serres-Bérard T, Pierre M, Chahine M, Puymirat J. Deciphering the mechanisms underlying brain alterations and cognitive impairment in congenital myotonic dystrophy. Neurobiol Dis 2021; 160:105532. [PMID: 34655747 DOI: 10.1016/j.nbd.2021.105532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/24/2021] [Accepted: 10/11/2021] [Indexed: 12/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic and heterogeneous disorder caused by the expansion of CTG repeats in the 3' UTR of the myotonic dystrophy protein kinase (DMPK) gene. There is a congenital form (CDM1) of the disease characterized by severe hypotonia, respiratory insufficiency as well as developmental delays and intellectual disabilities. CDM1 infants manifest important brain structure abnormalities present from birth while, in contrast, older patients with adult-onset DM1 often present neurodegenerative features and milder progressive cognitive deficits. Promising therapies targeting central molecular mechanisms contributing to the symptoms of adult-onset DM1 are currently in development, but their relevance for treating cognitive impairment in CDM1, which seems to be a partially distinct neurodevelopmental disorder, remain to be elucidated. Here, we provide an update on the clinical presentation of CDM1 and review recent in vitro and in vivo models that have provided meaningful insights on its consequences in development, with a particular focus on the brain. We discuss how enhanced toxic gain-of-function of the mutated DMPK transcripts with larger CUG repeats and the resulting dysregulation of RNA-binding proteins may affect the developing cortex in utero. Because the methylation of CpG islets flanking the trinucleotide repeats has emerged as a strong biomarker of CDM1, we highlight the need to investigate the tissue-specific impacts of these chromatin modifications in the brain. Finally, we outline promising potential therapeutic treatments for CDM1 and propose future in vitro and in vivo models with great potential to shed light on this disease.
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Affiliation(s)
- Thiéry De Serres-Bérard
- LOEX, CHU de Québec-Université Laval Research Center, Quebec City, Canada; CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, Canada
| | - Marion Pierre
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, Canada
| | - Mohamed Chahine
- CERVO Brain Research Center, Institut universitaire en santé mentale de Québec, Quebec City, Canada; Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Canada.
| | - Jack Puymirat
- LOEX, CHU de Québec-Université Laval Research Center, Quebec City, Canada; Department of Medicine, Faculty of Medicine, Université Laval, Quebec City, Canada
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