1
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Bohaczuk SC, Amador ZJ, Li C, Mallory BJ, Swanson EG, Ranchalis J, Vollger MR, Munson KM, Walsh T, Hamm MO, Mao Y, Lieber A, Stergachis AB. Resolving the chromatin impact of mosaic variants with targeted Fiber-seq. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.09.602608. [PMID: 39026856 PMCID: PMC11257596 DOI: 10.1101/2024.07.09.602608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Accurately quantifying the functional consequences of non-coding mosaic variants requires the pairing of DNA sequence with both accessible and closed chromatin architectures along individual DNA molecules-a pairing that cannot be achieved using traditional fragmentation-based chromatin assays. We demonstrate that targeted single-molecule chromatin fiber sequencing (Fiber-seq) achieves this, permitting single-molecule, long-read genomic and epigenomic profiling across targeted >100 kilobase loci with ~10-fold enrichment over untargeted sequencing. Targeted Fiber-seq reveals that pathogenic expansions of the DMPK CTG repeat that underlie Myotonic Dystrophy 1 are characterized by somatic instability and disruption of multiple nearby regulatory elements, both of which are repeat length-dependent. Furthermore, we reveal that therapeutic adenine base editing of the segmentally duplicated γ-globin (HBG1/HBG2) promoters in primary human hematopoietic cells induced towards an erythroblast lineage increases the accessibility of the HBG1 promoter as well as neighboring regulatory elements. Overall, we find that these non-protein coding mosaic variants can have complex impacts on chromatin architectures, including extending beyond the regulatory element harboring the variant.
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Affiliation(s)
- Stephanie C. Bohaczuk
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | - Zachary J. Amador
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Chang Li
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | | | - Elliott G. Swanson
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jane Ranchalis
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | - Mitchell R. Vollger
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | | | - Tom Walsh
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | - Morgan O. Hamm
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Yizi Mao
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | - Andre Lieber
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
| | - Andrew B. Stergachis
- Division of Medical Genetics, University of Washington School of Medicine, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA USA
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2
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Gadgil RY, Rider SD, Shrestha R, Alhawach V, Hitch D, Leffak M. Microsatellite break-induced replication generates highly mutagenized extrachromosomal circular DNAs. NAR Cancer 2024; 6:zcae027. [PMID: 38854437 PMCID: PMC11161834 DOI: 10.1093/narcan/zcae027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 06/11/2024] Open
Abstract
Extrachromosomal circular DNAs (eccDNAs) are produced from all regions of the eucaryotic genome. We used inverse PCR of non-B microsatellites capable of forming hairpin, triplex, quadruplex and AT-rich structures integrated at a common ectopic chromosomal site to show that these non-B DNAs generate highly mutagenized eccDNAs by replication-dependent mechanisms. Mutagenesis occurs within the non-B DNAs and extends several kilobases bidirectionally into flanking and nonallelic DNA. Each non-B DNA exhibits a different pattern of mutagenesis, while sister clones containing the same non-B DNA also display distinct patterns of recombination, microhomology-mediated template switching and base substitutions. Mutations include mismatches, short duplications, long nontemplated insertions, large deletions and template switches to sister chromatids and nonallelic chromosomes. Drug-induced replication stress or the depletion of DNA repair factors Rad51, the COPS2 signalosome subunit or POLη change the pattern of template switching and alter the eccDNA mutagenic profiles. We propose an asynchronous capture model based on break-induced replication from microsatellite-induced DNA double strand breaks to account for the generation and circularization of mutagenized eccDNAs and the appearance of genomic homologous recombination deficiency (HRD) scars. These results may help to explain the appearance of tumor eccDNAS and their roles in neoantigen production, oncogenesis and resistance to chemotherapy.
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Affiliation(s)
- Rujuta Yashodhan Gadgil
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - S Dean Rider
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Resha Shrestha
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Venicia Alhawach
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - David C Hitch
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Michael Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
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3
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Handal T, Juster S, Abu Diab M, Yanovsky-Dagan S, Zahdeh F, Aviel U, Sarel-Gallily R, Michael S, Bnaya E, Sebban S, Buganim Y, Drier Y, Mouly V, Kubicek S, van den Broek WJAA, Wansink DG, Epsztejn-Litman S, Eiges R. Differentiation shifts from a reversible to an irreversible heterochromatin state at the DM1 locus. Nat Commun 2024; 15:3270. [PMID: 38627364 PMCID: PMC11021500 DOI: 10.1038/s41467-024-47217-4] [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: 09/05/2021] [Accepted: 03/25/2024] [Indexed: 04/19/2024] Open
Abstract
Epigenetic defects caused by hereditary or de novo mutations are implicated in various human diseases. It remains uncertain whether correcting the underlying mutation can reverse these defects in patient cells. Here we show by the analysis of myotonic dystrophy type 1 (DM1)-related locus that in mutant human embryonic stem cells (hESCs), DNA methylation and H3K9me3 enrichments are completely abolished by repeat excision (CTG2000 expansion), whereas in patient myoblasts (CTG2600 expansion), repeat deletion fails to do so. This distinction between undifferentiated and differentiated cells arises during cell differentiation, and can be reversed by reprogramming of gene-edited myoblasts. We demonstrate that abnormal methylation in DM1 is distinctively maintained in the undifferentiated state by the activity of the de novo DNMTs (DNMT3b in tandem with DNMT3a). Overall, the findings highlight a crucial difference in heterochromatin maintenance between undifferentiated (sequence-dependent) and differentiated (sequence-independent) cells, thus underscoring the role of differentiation as a locking mechanism for repressive epigenetic modifications at the DM1 locus.
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Affiliation(s)
- Tayma Handal
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Sarah Juster
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Manar Abu Diab
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Shira Yanovsky-Dagan
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Fouad Zahdeh
- Medical Genetics Institute, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
| | - Uria Aviel
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Roni Sarel-Gallily
- The Azrieli Center for Stem Cells and Genetic Research, Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, 91904, Israel
| | - Shir Michael
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Ester Bnaya
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel
| | - Shulamit Sebban
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel
| | - Yosef Buganim
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel
| | - Yotam Drier
- The Lautenberg Center for Immunology and Cancer Research, IMRIC, Faculty of Medicine, The Hebrew University, Jerusalem, Israel
| | - Vincent Mouly
- Sorbonne Université, Inserm, Institut de Myologie, Centre de Recherche en Myologie, F-75013, Paris, France
| | - Stefan Kubicek
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090, Vienna, Austria
| | - Walther J A A van den Broek
- Department of Medical BioSciences, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Derick G Wansink
- Department of Medical BioSciences, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Silvina Epsztejn-Litman
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel
| | - Rachel Eiges
- Stem Cell Research Laboratory, Medical Genetics Institute, The Eisenberg R&D Authority, Shaare Zedek Medical Center, Jerusalem, 91031, Israel.
- The Hebrew University School of Medicine, Jerusalem, 91120, Israel.
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4
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Gadgil RY, Rider SD, Shrestha R, Alhawach V, Hitch DC, Leffak M. Microsatellite break-induced replication generates highly mutagenized extrachromosomal circular DNAs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.575055. [PMID: 38260482 PMCID: PMC10802558 DOI: 10.1101/2024.01.12.575055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Extrachromosomal circular DNAs (eccDNAs) are produced from all regions of the eucaryotic genome. In tumors, highly transcribed eccDNAs have been implicated in oncogenesis, neoantigen production and resistance to chemotherapy. Here we show that unstable microsatellites capable of forming hairpin, triplex, quadruplex and AT-rich structures generate eccDNAs when integrated at a common ectopic site in human cells. These non-B DNA prone microsatellites form eccDNAs by replication-dependent mechanisms. The microsatellite-based eccDNAs are highly mutagenized and display template switches to sister chromatids and to nonallelic chromosomal sites. High frequency mutagenesis occurs within the eccDNA microsatellites and extends bidirectionally for several kilobases into flanking DNA and nonallelic DNA. Mutations include mismatches, short duplications, longer nontemplated insertions and large deletions. Template switching leads to recurrent deletions and recombination domains within the eccDNAs. Template switching events are microhomology-mediated, but do not occur at all potential sites of complementarity. Each microsatellite exhibits a distinct pattern of recombination, microhomology choice and base substitution signature. Depletion of Rad51, the COPS2 signalosome subunit or POLη alter the eccDNA mutagenic profiles. We propose an asynchronous capture model based on break-induced replication from microsatellite-induced DNA breaks for the generation and circularization of mutagenized eccDNAs and genomic homologous recombination deficiency (HRD) scars.
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5
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da Silva CP, Camuzi D, Reis AHDO, Gonçalves AP, Dos Santos JM, Machado FB, Medina-Acosta E, Soares-Lima SC, Santos-Rebouças CB. Identification of a novel epigenetic marker for typical and mosaic presentations of Fragile X syndrome. Expert Rev Mol Diagn 2023; 23:1273-1281. [PMID: 37970883 DOI: 10.1080/14737159.2023.2284782] [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: 09/05/2023] [Accepted: 11/07/2023] [Indexed: 11/19/2023]
Abstract
BACKGROUND Fragile X syndrome (FXS) is primarily due to CGG repeat expansions in the FMR1 gene. FMR1 alleles are classified as normal (N), intermediate (I), premutation (PM), and full mutation (FM). FXS patients often carry an FM, but size mosaicism can occur. Additionally, loss of methylation boundary upstream of repeats results in de novo methylation spreading to FMR1 promoter in FXS patients. RESEARCH DESIGN AND METHODS This pilot study investigated the methylation boundary and adjacent regions in 66 males with typical and atypical FXS aged 1 to 30 years (10.86 ± 6.48 years). AmplideX FMR1 mPCR kit was used to discriminate allele profiles and methylation levels. CpG sites were assessed by pyrosequencing. RESULTS 40 out of 66 FXS patients (60.6%) showed an exclusive FM (n = 40), whereas the remaining (n = 26) exhibited size mosaicism [10 PM_FM (15.15%); 10 N_FM (15.15%); 2 N_PM_FM (3%)]. Four patients (6.1%) had deletions near repeats. Noteworthy, a CpG within FMR1 intron 2 displayed hypomethylation in FXS patients and hypermethylation in controls, demonstrating remarkable specificity, sensitivity, and accuracy when a methylation threshold of 69.5% was applied. CONCLUSIONS Since intragenic methylation is pivotal in gene regulation, the intronic CpG might be a novel epigenetic biomarker for FXS diagnosis.
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Affiliation(s)
- Camilla Pereira da Silva
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Diego Camuzi
- Molecular Carcinogenesis Program, Brazilian National Cancer Institute, Rio de Janeiro, Brazil
| | - Adriana Helena de Oliveira Reis
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Andressa Pereira Gonçalves
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jussara Mendonça Dos Santos
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Filipe Brum Machado
- Department of Biological Sciences, Minas Gerais State University, Minas Gerais, Brazil
| | - Enrique Medina-Acosta
- Biotechnology Laboratory, Molecular Diagnostic, and Research Center, State University of the North Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brazil
| | | | - Cíntia Barros Santos-Rebouças
- Department of Genetics, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil
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6
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Wright SE, Todd PK. Native functions of short tandem repeats. eLife 2023; 12:e84043. [PMID: 36940239 PMCID: PMC10027321 DOI: 10.7554/elife.84043] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 03/08/2023] [Indexed: 03/21/2023] Open
Abstract
Over a third of the human genome is comprised of repetitive sequences, including more than a million short tandem repeats (STRs). While studies of the pathologic consequences of repeat expansions that cause syndromic human diseases are extensive, the potential native functions of STRs are often ignored. Here, we summarize a growing body of research into the normal biological functions for repetitive elements across the genome, with a particular focus on the roles of STRs in regulating gene expression. We propose reconceptualizing the pathogenic consequences of repeat expansions as aberrancies in normal gene regulation. From this altered viewpoint, we predict that future work will reveal broader roles for STRs in neuronal function and as risk alleles for more common human neurological diseases.
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Affiliation(s)
- Shannon E Wright
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- Neuroscience Graduate Program, University of Michigan–Ann ArborAnn ArborUnited States
- Department of Neuroscience, Picower InstituteCambridgeUnited States
| | - Peter K Todd
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- VA Ann Arbor Healthcare SystemAnn ArborUnited States
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7
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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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8
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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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9
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Nakamori M, Shimizu H, Ogawa K, Hasuike Y, Nakajima T, Sakurai H, Araki T, Okada Y, Kakita A, Mochizuki H. Cell type-specific abnormalities of central nervous system in myotonic dystrophy type 1. Brain Commun 2022; 4:fcac154. [PMID: 35770133 PMCID: PMC9218787 DOI: 10.1093/braincomms/fcac154] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 03/13/2022] [Accepted: 06/09/2022] [Indexed: 11/17/2022] Open
Abstract
Myotonic dystrophy type 1 is a multisystem genetic disorder involving the muscle, heart and CNS. It is caused by toxic RNA transcription from expanded CTG repeats in the 3′-untranslated region of DMPK, leading to dysregulated splicing of various genes and multisystemic symptoms. Although aberrant splicing of several genes has been identified as the cause of some muscular symptoms, the pathogenesis of CNS symptoms prevalent in patients with myotonic dystrophy type 1 remains unelucidated, possibly due to a limitation in studying a diverse mixture of different cell types, including neuronal cells and glial cells. Previous studies revealed neuronal loss in the cortex, myelin loss in the white matter and the presence of axonal neuropathy in patients with myotonic dystrophy type 1. To elucidate the CNS pathogenesis, we investigated cell type-specific abnormalities in cortical neurons, white matter glial cells and spinal motor neurons via laser-capture microdissection. We observed that the CTG repeat instability and cytosine–phosphate–guanine (CpG) methylation status varied among the CNS cell lineages; cortical neurons had more unstable and longer repeats with higher CpG methylation than white matter glial cells, and spinal motor neurons had more stable repeats with lower methylation status. We also identified splicing abnormalities in each CNS cell lineage, such as DLGAP1 in white matter glial cells and CAMKK2 in spinal motor neurons. Furthermore, we demonstrated that aberrant splicing of CAMKK2 is associated with abnormal neurite morphology in myotonic dystrophy type 1 motor neurons. Our laser-capture microdissection-based study revealed cell type-dependent genetic, epigenetic and splicing abnormalities in myotonic dystrophy type 1 CNS, indicating the significant potential of cell type-specific analysis in elucidating the CNS pathogenesis.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine , 2-2 Yamadaoka, Suita, Osaka 565-0871 , Japan
- Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University , 1-1 Yamadaoka, Suita, Osaka 565-0871 , Japan
| | - Hiroshi Shimizu
- Department of Pathology, Brain Research Institute, Niigata University , 1-757 Asahimachi, Chuo-ku, Niigata 951-8585 , Japan
| | - Kotaro Ogawa
- Department of Neurology, Osaka University Graduate School of Medicine , 2-2 Yamadaoka, Suita, Osaka 565-0871 , Japan
- Department of Statistical Genetics, Osaka University Graduate School of Medicine , 2-2 Yamadaoka, Suita, Osaka 565-0871 , Japan
| | - Yuhei Hasuike
- Department of Neurology, Osaka University Graduate School of Medicine , 2-2 Yamadaoka, Suita, Osaka 565-0871 , Japan
| | - Takashi Nakajima
- Department of Neurology, National Hospital Organization Niigata National Hospital , 3-52 Akasakamachi, Kashiwazaki, Niigata 945-8585 , Japan
| | - Hidetoshi Sakurai
- Center for iPS Cell Research and Application (CiRA), Kyoto University , 53 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507 , Japan
| | - Toshiyuki Araki
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry , 4-1-1 Ogawahigashimachi, Kodaira, Tokyo 187-8502 , Japan
| | - Yukinori Okada
- Department of Statistical Genetics, Osaka University Graduate School of Medicine , 2-2 Yamadaoka, Suita, Osaka 565-0871 , Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, Niigata University , 1-757 Asahimachi, Chuo-ku, Niigata 951-8585 , Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine , 2-2 Yamadaoka, Suita, Osaka 565-0871 , Japan
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10
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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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11
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Franck S, Couvreu De Deckersberg E, Bubenik JL, Markouli C, Barbé L, Allemeersch J, Hilven P, Duqué G, Swanson MS, Gheldof A, Spits C, Sermon KD. Myotonic dystrophy type 1 embryonic stem cells show decreased myogenic potential, increased CpG methylation at the DMPK locus and RNA mis-splicing. Biol Open 2022; 11:273965. [PMID: 35019138 PMCID: PMC8764412 DOI: 10.1242/bio.058978] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/29/2021] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle tissue is severely affected in myotonic dystrophy type 1 (DM1) patients, characterised by muscle weakness, myotonia and muscle immaturity in the most severe congenital form of the disease. Previously, it was not known at what stage during myogenesis the DM1 phenotype appears. In this study we differentiated healthy and DM1 human embryonic stem cells to myoblasts and myotubes and compared their differentiation potential using a comprehensive multi-omics approach. We found myogenesis in DM1 cells to be abnormal with altered myotube generation compared to healthy cells. We did not find differentially expressed genes between DM1 and non-DM1 cell lines within the same developmental stage. However, during differentiation we observed an aberrant inflammatory response and increased CpG methylation upstream of the CTG repeat at the myoblast level and RNA mis-splicing at the myotube stage. We show that early myogenesis modelled in hESC reiterates the early developmental manifestation of DM1. Summary: Early developmental abnormalities in myotonic dystrophy type 1 are reiterated in vitro in myotubes differentiated from human embryonic stem cells that carry the mutation.
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Affiliation(s)
- Silvie Franck
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | | | - Jodi L Bubenik
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Christina Markouli
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Lise Barbé
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, 94107 CA, United States
| | | | - Pierre Hilven
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Geoffrey Duqué
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - 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
| | - Alexander Gheldof
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium.,Center for Medical Genetics, UZ Brussel, Brussels 1090, Belgium
| | - Claudia Spits
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Karen D Sermon
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
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12
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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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13
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Wieben ED, Aleff RA, Rinkoski TA, Baratz KH, Basu S, Patel SV, Maguire LJ, Fautsch MP. Comparison of TCF4 repeat expansion length in corneal endothelium and leukocytes of patients with Fuchs endothelial corneal dystrophy. PLoS One 2021; 16:e0260837. [PMID: 34855896 PMCID: PMC8638873 DOI: 10.1371/journal.pone.0260837] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 11/17/2021] [Indexed: 12/13/2022] Open
Abstract
Expansion of CTG trinucleotide repeats (TNR) in the transcription factor 4 (TCF4) gene is highly associated with Fuchs Endothelial Corneal Dystrophy (FECD). Due to limitations in the availability of DNA from diseased corneal endothelium, sizing of CTG repeats in FECD patients has typically been determined using DNA samples isolated from peripheral blood leukocytes. However, it is non-feasible to extract enough DNA from surgically isolated FECD corneal endothelial tissue to determine repeat length based on current technology. To circumvent this issue, total RNA was isolated from FECD corneal endothelium and sequenced using long-read sequencing. Southern blotting of DNA samples isolated from primary cultures of corneal endothelium from these same affected individuals was also assessed. Both long read sequencing and Southern blot analysis showed significantly longer CTG TNR expansion (>1000 repeats) in the corneal endothelium from FECD patients than those characterized in leukocytes from the same individuals (<90 repeats). Our findings suggest that the TCF4 CTG repeat expansions in the FECD corneal endothelium are much longer than those found in leukocytes.
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Affiliation(s)
- Eric D. Wieben
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Ross A. Aleff
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Tommy A. Rinkoski
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Keith H. Baratz
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Shubham Basu
- Division of Biostatistics and Bioinformatics and Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Sanjay V. Patel
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Leo J. Maguire
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
| | - Michael P. Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United states of America
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14
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Visconti VV, Centofanti F, Fittipaldi S, Macrì E, Novelli G, Botta A. Epigenetics of Myotonic Dystrophies: A Minireview. Int J Mol Sci 2021; 22:ijms222212594. [PMID: 34830473 PMCID: PMC8623789 DOI: 10.3390/ijms222212594] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 11/19/2021] [Accepted: 11/20/2021] [Indexed: 12/14/2022] Open
Abstract
Myotonic dystrophy type 1 and 2 (DM1 and DM2) are two multisystemic autosomal dominant disorders with clinical and genetic similarities. The prevailing paradigm for DMs is that they are mediated by an in trans toxic RNA mechanism, triggered by untranslated CTG and CCTG repeat expansions in the DMPK and CNBP genes for DM1 and DM2, respectively. Nevertheless, increasing evidences suggest that epigenetics can also play a role in the pathogenesis of both diseases. In this review, we discuss the available information on epigenetic mechanisms that could contribute to the DMs outcome and progression. Changes in DNA cytosine methylation, chromatin remodeling and expression of regulatory noncoding RNAs are described, with the intent of depicting an epigenetic signature of DMs. Epigenetic biomarkers have a strong potential for clinical application since they could be used as targets for therapeutic interventions avoiding changes in DNA sequences. Moreover, understanding their clinical significance may serve as a diagnostic indicator in genetic counselling in order to improve genotype–phenotype correlations in DM patients.
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Affiliation(s)
- Virginia Veronica Visconti
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Federica Centofanti
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Simona Fittipaldi
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Elisa Macrì
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
| | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
- IRCCS (Institute for Treatment and Research) Neuromed, 86077 Pozzilli, Italy
- Department of Pharmacology, School of Medicine, University of Nevada, Reno, NV 89557, USA
| | - Annalisa Botta
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome “Tor Vergata”, Via Montpellier 1, 00133 Rome, Italy; (V.V.V.); (F.C.); (S.F.); (E.M.); (G.N.)
- Correspondence: ; Tel.: +39-6-7259-6078
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15
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Abstract
At fifteen different genomic locations, the expansion of a CAG/CTG repeat causes a neurodegenerative or neuromuscular disease, the most common being Huntington's disease and myotonic dystrophy type 1. These disorders are characterized by germline and somatic instability of the causative CAG/CTG repeat mutations. Repeat lengthening, or expansion, in the germline leads to an earlier age of onset or more severe symptoms in the next generation. In somatic cells, repeat expansion is thought to precipitate the rate of disease. The mechanisms underlying repeat instability are not well understood. Here we review the mammalian model systems that have been used to study CAG/CTG repeat instability, and the modifiers identified in these systems. Mouse models have demonstrated prominent roles for proteins in the mismatch repair pathway as critical drivers of CAG/CTG instability, which is also suggested by recent genome-wide association studies in humans. We draw attention to a network of connections between modifiers identified across several systems that might indicate pathway crosstalk in the context of repeat instability, and which could provide hypotheses for further validation or discovery. Overall, the data indicate that repeat dynamics might be modulated by altering the levels of DNA metabolic proteins, their regulation, their interaction with chromatin, or by direct perturbation of the repeat tract. Applying novel methodologies and technologies to this exciting area of research will be needed to gain deeper mechanistic insight that can be harnessed for therapies aimed at preventing repeat expansion or promoting repeat contraction.
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Affiliation(s)
- Vanessa C. Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA,Department of Neurology, Harvard Medical School, Boston, MA, USA,Correspondence to: Vanessa C. Wheeler, Center for Genomic Medicine, Massachusetts Hospital, Boston MAA 02115, USA. E-mail: . and Vincent Dion, UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK. E-mail:
| | - Vincent Dion
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, UK,Correspondence to: Vanessa C. Wheeler, Center for Genomic Medicine, Massachusetts Hospital, Boston MAA 02115, USA. E-mail: . and Vincent Dion, UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK. E-mail:
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16
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DMPK hypermethylation in sperm cells of myotonic dystrophy type 1 patients. Eur J Hum Genet 2021; 30:980-983. [PMID: 34776509 PMCID: PMC9349176 DOI: 10.1038/s41431-021-00999-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 10/12/2021] [Accepted: 10/26/2021] [Indexed: 12/03/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant muscular dystrophy that results from a CTG expansion (50–4000 copies) in the 3′ UTR of the DMPK gene. The disease is classified into four or five somewhat overlapping forms, which incompletely correlate with expansion size in somatic cells of patients. With rare exception, it is affected mothers who transmit the congenital (CDM1) and most severe form of the disease. Why CDM1 is hardly ever transmitted by fathers remains unknown. One model to explain the almost exclusive transmission of CDM1 by affected mothers suggests a selection against hypermethylated large expansions in the germline of male patients. By assessing DNA methylation upstream to the CTG expansion in motile sperm cells of four DM1 patients, together with availability of human embryonic stem cell (hESCs) lines with paternally inherited hypermethylated expansions, we exclude the possibility that DMPK hypermethylation leads to selection against viable sperm cells (as indicated by motility) in DM1 patients.
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17
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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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18
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Yang B, Borgeaud AC, Buřičová M, Aeschbach L, Rodríguez-Lima O, Ruiz Buendía GA, Cinesi C, Taylor AS, Baubec T, Dion V. Expanded CAG/CTG repeats resist gene silencing mediated by targeted Epigenome editing. Hum Mol Genet 2021; 31:386-398. [PMID: 34494094 PMCID: PMC8825355 DOI: 10.1093/hmg/ddab255] [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: 11/04/2020] [Revised: 05/08/2021] [Accepted: 08/25/2021] [Indexed: 11/14/2022] Open
Abstract
Expanded CAG/CTG repeat disorders affect over 1 in 2500 individuals worldwide. Potential therapeutic avenues include gene silencing and modulation of repeat instability. However, there are major mechanistic gaps in our understanding of these processes, which prevent the rational design of an efficient treatment. To address this, we developed a novel system, ParB/ANCHOR-mediated Inducible Targeting (PInT), in which any protein can be recruited at will to a GFP reporter containing an expanded CAG/CTG repeat. Previous studies have implicated the histone deacetylase HDAC5 and the DNA methyltransferase DNMT1 as modulators of repeat instability via mechanisms that are not fully understood. Using PInT, we found no evidence that HDAC5 or DNMT1 modulate repeat instability upon targeting to the expanded repeat, suggesting that their effect is independent of local chromatin structure. Unexpectedly, we found that expanded CAG/CTG repeats reduce the effectiveness of gene silencing mediated by targeting HDAC5 and DNMT1. The repeat-length effect in gene silencing by HDAC5 was abolished by a small molecule inhibitor of HDAC3. Our results have important implications on the design of epigenome editing approaches for expanded CAG/CTG repeat disorders. PInT is a versatile synthetic system to study the effect of any sequence of interest on epigenome editing.
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Affiliation(s)
- Bin Yang
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Alicia C Borgeaud
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland.,UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
| | - Marcela Buřičová
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
| | - Lorène Aeschbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Oscar Rodríguez-Lima
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Gustavo A Ruiz Buendía
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Cinzia Cinesi
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Alysha S Taylor
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
| | - Tuncay Baubec
- Department of Molecular Mechanisms of Disease, University of Zurich, 8057, Zurich, Switzerland
| | - Vincent Dion
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
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19
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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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20
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Mouro Pinto R, Arning L, Giordano JV, Razghandi P, Andrew MA, Gillis T, Correia K, Mysore JS, Grote Urtubey DM, Parwez CR, von Hein SM, Clark HB, Nguyen HP, Förster E, Beller A, Jayadaev S, Keene CD, Bird TD, Lucente D, Vonsattel JP, Orr H, Saft C, Petrasch-Parwez E, Wheeler VC. Patterns of CAG repeat instability in the central nervous system and periphery in Huntington's disease and in spinocerebellar ataxia type 1. Hum Mol Genet 2021; 29:2551-2567. [PMID: 32761094 PMCID: PMC7471505 DOI: 10.1093/hmg/ddaa139] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/24/2020] [Accepted: 07/01/2020] [Indexed: 12/23/2022] Open
Abstract
The expanded HTT CAG repeat causing Huntington’s disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.
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Affiliation(s)
- Ricardo Mouro Pinto
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Larissa Arning
- Department of Human Genetics, Ruhr-University Bochum, Bochum 44780, Germany
| | - James V Giordano
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Pedram Razghandi
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Marissa A Andrew
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Tammy Gillis
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Kevin Correia
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jayalakshmi S Mysore
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | | | - Constanze R Parwez
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Sarah M von Hein
- Department of Neurology, Huntington Centre NRW, St. Josef-Hospital, Ruhr-University Bochum, Bochum 44791, Germany
| | - H Brent Clark
- Department of Laboratory Medicine and Pathology, Institute of Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Huu Phuc Nguyen
- Department of Human Genetics, Ruhr-University Bochum, Bochum 44780, Germany
| | - Eckart Förster
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Allison Beller
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Suman Jayadaev
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA
| | - C Dirk Keene
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
| | - Thomas D Bird
- Department of Neurology, University of Washington, Seattle, Washington 98195, USA.,Department of Medicine, University of Washington, Seattle, Washington 98195, USA.,Geriatrics Research Education and Clinical Center, VA Puget Sound Medical Center, Seattle, WA 98108, USA
| | - Diane Lucente
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jean-Paul Vonsattel
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY 10032, USA
| | - Harry Orr
- Department of Laboratory Medicine and Pathology, Institute of Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Carsten Saft
- Department of Neurology, Huntington Centre NRW, St. Josef-Hospital, Ruhr-University Bochum, Bochum 44791, Germany
| | - Elisabeth Petrasch-Parwez
- Department of Neuroanatomy and Molecular Brain Research, Institute of Anatomy, Ruhr-University Bochum, Bochum 44780, Germany
| | - Vanessa C Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
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21
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Morales F, Corrales E, Zhang B, Vásquez M, Santamaría-Ulloa C, Quesada H, Sirito M, Estecio MR, Monckton DG, Krahe R. Myotonic dystrophy type 1 (DM1) clinical sub-types and CTCF site methylation status flanking the CTG expansion are mutant allele length-dependent. Hum Mol Genet 2021; 31:262-274. [PMID: 34432028 DOI: 10.1093/hmg/ddab243] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a complex disease with a wide spectrum of symptoms. The exact relationship between mutant CTG repeat expansion size and clinical outcome remains unclear. DM1 congenital patients (CDM) inherit the largest expanded alleles, which are associated with abnormal and increased DNA methylation flanking the CTG repeat. However, DNA methylation at the DMPK locus remains understudied. Its relationship to DM1 clinical subtypes, expansion size and age-at-onset is not yet completely understood. Using pyrosequencing-based methylation analysis on 225 blood DNA samples from Costa Rican DM1 patients, we determined that the size of the estimated progenitor allele length (ePAL) is not only a good discriminator between CDM and non-CDM cases (with an estimated threshold at 653 CTG repeats), but also for all DM1 clinical subtypes. Secondly, increased methylation at both CTCF sites upstream and downstream of the expansion was almost exclusively present in CDM cases. Thirdly, levels of abnormal methylation were associated with clinical subtype, age and ePAL, with strong correlations between these variables. Fourthly, both ePAL and the intergenerational expansion size were significantly associated with methylation status. Finally, methylation status was associated with ePAL and maternal inheritance, with almost exclusively maternal transmission of CDM. In conclusion, increased DNA methylation at the CTCF sites flanking the DM1 expansion could be linked to ePAL, and both increased methylation and the ePAL could be considered biomarkers for the CDM phenotype.
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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
| | - Baili Zhang
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, Texas, 77030-4009, USA
| | - Melissa Vásquez
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, 2060, Costa Rica
| | - Carolina Santamaría-Ulloa
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, 2060, Costa Rica
| | - Hazel Quesada
- Instituto de Investigaciones en Salud (INISA), Universidad de Costa Rica, San José, 2060, Costa Rica
| | - Mario Sirito
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, Texas, 77030-4009, USA
| | - Marcos R Estecio
- Department of Epigenetics & Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, Texas, 77030-4009, USA.,Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Houston, Texas, 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, United Kingdom
| | - Ralf Krahe
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, Texas, 77030-4009, USA.,Center for Cancer Epigenetics, University of Texas MD Anderson Cancer Center, Houston, Texas, 77030-4009, USA
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22
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Breton É, Légaré C, Overend G, Guay SP, Monckton D, Mathieu J, Gagnon C, Richer L, Gallais B, Bouchard L. DNA methylation at the DMPK gene locus is associated with cognitive functions in myotonic dystrophy type 1. Epigenomics 2020; 12:2051-2064. [PMID: 33301350 DOI: 10.2217/epi-2020-0328] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Aim: Myotonic dystrophy type 1 (DM1) is caused by an unstable trinucleotide (CTG) expansion at the DMPK gene locus. Cognitive dysfunctions are often observed in the condition. We investigated the association between DMPK blood DNA methylation (DNAm) and cognitive functions in DM1, considering expansion length and variant repeats (VRs). Method: Data were obtained from 115 adult-onset DM1 patients. Molecular analyses consisted of pyrosequencing, small pool PCR and Southern blot hybridization. Cognitive functions were assessed by validated neuropsychological tests. Results: For patients without VRs (n = 103), blood DNAm at baseline independently contributed to predict cognitive functions 9 years later. Patients with VRs (n = 12) had different DNAm and cognitive profiles. Conclusion: DNAm allows to better understand DM1-related cognitive dysfunction etiology.
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Affiliation(s)
- Édith Breton
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada
| | - Cécilia Légaré
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada
| | - Gayle Overend
- Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Simon-Pierre Guay
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Centre, Montreal, QC H4A 3J1, Canada
| | - Darren Monckton
- Institute of Molecular, Cell & Systems Biology, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Jean Mathieu
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Centre de recherche Charles-Le-Moyne-Saguenay-Lac-Saint-Jean sur les innovations en santé (CR-CSIS), Université de Sherbrooke, Saguenay, Québec G7H 5H6, Canada
| | - Cynthia Gagnon
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Centre de recherche Charles-Le-Moyne-Saguenay-Lac-Saint-Jean sur les innovations en santé (CR-CSIS), Université de Sherbrooke, Saguenay, Québec G7H 5H6, Canada
| | - Louis Richer
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Department of Health Sciences, Université du Québec à Chicoutimi (UQAC), Saguenay, Québec G7H 2B1, Canada
| | - Benjamin Gallais
- Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Centre de recherche Charles-Le-Moyne-Saguenay-Lac-Saint-Jean sur les innovations en santé (CR-CSIS), Université de Sherbrooke, Saguenay, Québec G7H 5H6, Canada.,ÉCOBES - Recherche et transfert, Cégep de Jonquière, Saguenay, Québec G7X 7W2, Canada
| | - Luigi Bouchard
- Department of Biochemistry & Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.,Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Jonquière, Saguenay, Québec G7X 7X2, Canada.,Department of Medical Biology, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Saguenay-Lac-St-Jean - Hôpital de Chicoutimi, Saguenay, Québec G7H 5H6, Canada
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23
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Franck S, Barbé L, Ardui S, De Vlaeminck Y, Allemeersch J, Dziedzicka D, Spits C, Vanroye F, Hilven P, Duqué G, Vermeesch JR, Gheldof A, Sermon K. MSH2 knock-down shows CTG repeat stability and concomitant upstream demethylation at the DMPK locus in myotonic dystrophy type 1 human embryonic stem cells. Hum Mol Genet 2020; 29:3566-3577. [PMID: 33242073 DOI: 10.1093/hmg/ddaa250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/20/2020] [Accepted: 11/20/2020] [Indexed: 12/14/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is caused by expansion of a CTG repeat in the DMPK gene, where expansion size and somatic mosaicism correlates with disease severity and age of onset. While it is known that the mismatch repair protein MSH2 contributes to the unstable nature of the repeat, its role on other disease-related features, such as CpG methylation upstream of the repeat, is unknown. In this study, we investigated the effect of an MSH2 knock-down (MSH2KD) on both CTG repeat dynamics and CpG methylation pattern in human embryonic stem cells (hESC) carrying the DM1 mutation. Repeat size in MSH2 wild-type (MSH2WT) and MSH2KD DM1 hESC was determined by PacBio sequencing and CpG methylation by bisulfite massive parallel sequencing. We found stabilization of the CTG repeat concurrent with a gradual loss of methylation upstream of the repeat in MSH2KD cells, while the repeat continued to expand and upstream methylation remained unchanged in MSH2WT control lines. Repeat instability was re-established and biased towards expansions upon MSH2 transgenic re-expression in MSH2KD lines while upstream methylation was not consistently re-established. We hypothesize that the hypermethylation at the mutant DM1 locus is promoted by the MMR machinery and sustained by a constant DNA repair response, establishing a potential mechanistic link between CTG repeat instability and upstream CpG methylation. Our work represents a first step towards understanding how epigenetic alterations and repair pathways connect and contribute to the DM1 pathology.
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Affiliation(s)
- Silvie Franck
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Lise Barbé
- Center for systems and Therapeutics, Gladstone Institutes, Finkbeiner lab, San Francisco, CA 94158, USA
| | - Simon Ardui
- Center of Human Genetics, University Hospital Leuven, KU Leuven, Laboratory for Cytogenetics and Genome Research, Leuven 3000, Belgium
| | - Yannick De Vlaeminck
- Laboratory for Molecular and Cellular Therapy, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | | | - Dominika Dziedzicka
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Claudia Spits
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Fien Vanroye
- Laboratory HIV/STD, Institute of Tropical Medicine Antwerp, Antwerp 2000, Belgium
| | - Pierre Hilven
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Geoffrey Duqué
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Joris R Vermeesch
- Center of Human Genetics, University Hospital Leuven, KU Leuven, Laboratory for Cytogenetics and Genome Research, Leuven 3000, Belgium
| | - Alexander Gheldof
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium.,Center of Medical Genetics, UZ Brussel, Brussels 1090, Belgium
| | - Karen Sermon
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
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24
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Abstract
Neuromuscular disorders are a heterogeneous group of conditions affecting the neuromuscular system. The aim of this article is to review the major epigenetic findings in motor neuron diseases and major hereditary muscular dystrophies. DNA methylation changes are observed in both hereditary and sporadic forms, and combining DNA methylation analysis with mutational screening holds the potential for better diagnostic and prognostic accuracy. Novel, less toxic and more selective epigenetic drugs are designed and tested in animal and cell culture models of neuromuscular disorders, and non-coding RNAs are being investigated as either disease biomarkers or targets of therapeutic approaches to restore gene expression levels. Overall, neuromuscular disorder epigenetic biomarkers have a strong potential for clinical applications in the near future.
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Affiliation(s)
- Fabio Coppedè
- Department of Translational Research & of New Surgical & Medical Technologies, University of Pisa, Via Roma 55, 56126 Pisa, Italy
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25
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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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26
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Fautsch MP, Wieben ED, Baratz KH, Bhattacharyya N, Sadan AN, Hafford-Tear NJ, Tuft SJ, Davidson AE. TCF4-mediated Fuchs endothelial corneal dystrophy: Insights into a common trinucleotide repeat-associated disease. Prog Retin Eye Res 2020; 81:100883. [PMID: 32735996 PMCID: PMC7988464 DOI: 10.1016/j.preteyeres.2020.100883] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/24/2020] [Accepted: 07/04/2020] [Indexed: 12/13/2022]
Abstract
Fuchs endothelial corneal dystrophy (FECD) is a common cause for heritable visual loss in the elderly. Since the first description of an association between FECD and common polymorphisms situated within the transcription factor 4 (TCF4) gene, genetic and molecular studies have implicated an intronic CTG trinucleotide repeat (CTG18.1) expansion as a causal variant in the majority of FECD patients. To date, several non-mutually exclusive mechanisms have been proposed that drive and/or exacerbate the onset of disease. These mechanisms include (i) TCF4 dysregulation; (ii) toxic gain-of-function from TCF4 repeat-containing RNA; (iii) toxic gain-of-function from repeat-associated non-AUG dependent (RAN) translation; and (iv) somatic instability of CTG18.1. However, the relative contribution of these proposed mechanisms in disease pathogenesis is currently unknown. In this review, we summarise research implicating the repeat expansion in disease pathogenesis, define the phenotype-genotype correlations between FECD and CTG18.1 expansion, and provide an update on research tools that are available to study FECD as a trinucleotide repeat expansion disease. Furthermore, ongoing international research efforts to develop novel CTG18.1 expansion-mediated FECD therapeutics are highlighted and we provide a forward-thinking perspective on key unanswered questions that remain in the field. FECD is a common, age-related corneal dystrophy. The majority of cases are associated with expansion of a CTG repeat (CTG18.1). FECD is the most common trinucleotide repeat expansion disease in humans. Evidence supports multiple molecular mechanisms underlying the pathophysiology. Novel CTG18.1-targeted therapeutics are in development.
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Affiliation(s)
- Michael P Fautsch
- Department of Ophthalmology, 200 1st St SW, Mayo Clinic, Rochester, MN, 55905, USA.
| | - Eric D Wieben
- Department of Biochemistry and Molecular Biology, 200 1st St SW, Mayo Clinic, Rochester, MN, USA.
| | - Keith H Baratz
- Department of Ophthalmology, 200 1st St SW, Mayo Clinic, Rochester, MN, 55905, USA.
| | | | - Amanda N Sadan
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK.
| | | | - Stephen J Tuft
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK; Moorfields Eye Hospital, London, EC1V 2PD, UK.
| | - Alice E Davidson
- University College London Institute of Ophthalmology, London, ECIV 9EL, UK.
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27
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Ruiz Buendía GA, Leleu M, Marzetta F, Vanzan L, Tan JY, Ythier V, Randall EL, Marques AC, Baubec T, Murr R, Xenarios I, Dion V. Three-dimensional chromatin interactions remain stable upon CAG/CTG repeat expansion. SCIENCE ADVANCES 2020; 6:eaaz4012. [PMID: 32656337 PMCID: PMC7334000 DOI: 10.1126/sciadv.aaz4012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 05/19/2020] [Indexed: 06/11/2023]
Abstract
Expanded CAG/CTG repeats underlie 13 neurological disorders, including myotonic dystrophy type 1 (DM1) and Huntington's disease (HD). Upon expansion, disease loci acquire heterochromatic characteristics, which may provoke changes to chromatin conformation and thereby affect both gene expression and repeat instability. Here, we tested this hypothesis by performing 4C sequencing at the DMPK and HTT loci from DM1 and HD-derived cells. We find that allele sizes ranging from 15 to 1700 repeats displayed similar chromatin interaction profiles. This was true for both loci and for alleles with different DNA methylation levels and CTCF binding. Moreover, the ectopic insertion of an expanded CAG repeat tract did not change the conformation of the surrounding chromatin. We conclude that CAG/CTG repeat expansions are not enough to alter chromatin conformation in cis. Therefore, it is unlikely that changes in chromatin interactions drive repeat instability or changes in gene expression in these disorders.
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Affiliation(s)
- Gustavo A. Ruiz Buendía
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Marion Leleu
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Vital-IT Group, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Flavia Marzetta
- Vital-IT Group, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Ludovica Vanzan
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland
| | - Jennifer Y. Tan
- Department of Computational Biology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Victor Ythier
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland
| | - Emma L. Randall
- UK Dementia Research Institute at Cardiff University at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK
| | - Ana C. Marques
- Department of Computational Biology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Tuncay Baubec
- Department of Molecular Mechanisms of Disease, University of Zurich, 8057 Zurich, Switzerland
| | - Rabih Murr
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva, Switzerland
- Institute for Genetics and Genomics in Geneva (iGE3), University of Geneva, 1211 Geneva, Switzerland
| | - Ioannis Xenarios
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Vincent Dion
- UK Dementia Research Institute at Cardiff University at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK
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28
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Poeta L, Drongitis D, Verrillo L, Miano MG. DNA Hypermethylation and Unstable Repeat Diseases: A Paradigm of Transcriptional Silencing to Decipher the Basis of Pathogenic Mechanisms. Genes (Basel) 2020; 11:E684. [PMID: 32580525 PMCID: PMC7348995 DOI: 10.3390/genes11060684] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/12/2022] Open
Abstract
Unstable repeat disorders comprise a variable group of incurable human neurological and neuromuscular diseases caused by an increase in the copy number of tandem repeats located in various regions of their resident genes. It has become clear that dense DNA methylation in hyperexpanded non-coding repeats induces transcriptional silencing and, subsequently, insufficient protein synthesis. However, the ramifications of this paradigm reveal a far more profound role in disease pathogenesis. This review will summarize the significant progress made in a subset of non-coding repeat diseases demonstrating the role of dense landscapes of 5-methylcytosine (5mC) as a common disease modifier. However, the emerging findings suggest context-dependent models of 5mC-mediated silencing with distinct effects of excessive DNA methylation. An in-depth understanding of the molecular mechanisms underlying this peculiar group of human diseases constitutes a prerequisite that could help to discover novel pathogenic repeat loci, as well as to determine potential therapeutic targets. In this regard, we report on a brief description of advanced strategies in DNA methylation profiling for the identification of unstable Guanine-Cytosine (GC)-rich regions and on promising examples of molecular targeted therapies for Fragile X disease (FXS) and Friedrich ataxia (FRDA) that could pave the way for the application of this technique in other hypermethylated expansion disorders.
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Affiliation(s)
- Loredana Poeta
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso”, CNR, 80131 Naples, Italy; (L.P.); (D.D.); (L.V.)
| | - Denise Drongitis
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso”, CNR, 80131 Naples, Italy; (L.P.); (D.D.); (L.V.)
| | - Lucia Verrillo
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso”, CNR, 80131 Naples, Italy; (L.P.); (D.D.); (L.V.)
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania “Luigi Vanvitelli”, 81100 Caserta, Italy
| | - Maria Giuseppina Miano
- Institute of Genetics and Biophysics “Adriano Buzzati-Traverso”, CNR, 80131 Naples, Italy; (L.P.); (D.D.); (L.V.)
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29
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Khristich AN, Mirkin SM. On the wrong DNA track: Molecular mechanisms of repeat-mediated genome instability. J Biol Chem 2020; 295:4134-4170. [PMID: 32060097 PMCID: PMC7105313 DOI: 10.1074/jbc.rev119.007678] [Citation(s) in RCA: 155] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Expansions of simple tandem repeats are responsible for almost 50 human diseases, the majority of which are severe, degenerative, and not currently treatable or preventable. In this review, we first describe the molecular mechanisms of repeat-induced toxicity, which is the connecting link between repeat expansions and pathology. We then survey alternative DNA structures that are formed by expandable repeats and review the evidence that formation of these structures is at the core of repeat instability. Next, we describe the consequences of the presence of long structure-forming repeats at the molecular level: somatic and intergenerational instability, fragility, and repeat-induced mutagenesis. We discuss the reasons for gender bias in intergenerational repeat instability and the tissue specificity of somatic repeat instability. We also review the known pathways in which DNA replication, transcription, DNA repair, and chromatin state interact and thereby promote repeat instability. We then discuss possible reasons for the persistence of disease-causing DNA repeats in the genome. We describe evidence suggesting that these repeats are a payoff for the advantages of having abundant simple-sequence repeats for eukaryotic genome function and evolvability. Finally, we discuss two unresolved fundamental questions: (i) why does repeat behavior differ between model systems and human pedigrees, and (ii) can we use current knowledge on repeat instability mechanisms to cure repeat expansion diseases?
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Affiliation(s)
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, Massachusetts 02155.
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30
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Joosten IBT, Hellebrekers DMEI, de Greef BTA, Smeets HJM, de Die-Smulders CEM, Faber CG, Gerrits MM. Parental repeat length instability in myotonic dystrophy type 1 pre- and protomutations. Eur J Hum Genet 2020; 28:956-962. [PMID: 32203199 DOI: 10.1038/s41431-020-0601-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 02/14/2020] [Accepted: 02/25/2020] [Indexed: 01/03/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is caused by a CTG trinucleotide repeat expansion on chromosome 19q13.3. While DM1 premutation (36-50 repeats) and protomutation (51-80 repeats) allele carriers are mostly asymptomatic, offspring is at risk of inheriting expanded, symptom-associated, (CTG)n repeats of n > 80. In this study we aimed to evaluate the intergenerational instability of DM1 pre- and protomutation alleles, focussing on the influence of parental gender. One hundred and forty-six parent-child pairs (34 parental premutations, 112 protomutations) were retrospectively selected from the DM1 patient cohort of the Maastricht University Medical Center+. CTG repeat size of parents and children was determined by (triplet-primed) PCR followed by fragment length analysis and Southern blot analysis. Fifty-eight out of eighty-one (71.6%) paternal transmissions led to a (CTG)n repeat of n > 80 in offspring, compared with 15 out of 65 (23.1%) maternal transmissions (p < 0.001). Repeat length instability occurred for paternal (CTG)n repeats of n ≥ 45, while maternal instability did not occur until (CTG)n repeats reached a length of n ≥ 71. Transmission of premutations caused (CTG)n repeats of n > 80 in offspring only when paternally transmitted (two cases), while protomutations caused (CTG)n repeats of n > 80 in offspring in 71 cases, of which 56 (78.9%) were paternally transmitted. In conclusion, our data show that paternally transmitted pre- and protomutations were more unstable than maternally transmitted pre- and protomutations. For genetic counseling, this implies that males with a small DMPK mutation have a higher risk of symptomatic offspring compared with females. Consequently, we suggest addressing sex-dependent factors in genetic counseling of small-sized CTG repeat carriers.
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Affiliation(s)
- Isis B T Joosten
- Department of Neurology, Maastricht University Medical Center+, Maastricht, The Netherlands.,School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Bianca T A de Greef
- Department of Neurology, Maastricht University Medical Center+, Maastricht, The Netherlands.,School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Clinical Epidemiology and Medical Technology Assessment, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Hubert J M Smeets
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Clinical Genomics Unit, Maastricht University, Maastricht, The Netherlands.,School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands
| | | | - Catharina G Faber
- Department of Neurology, Maastricht University Medical Center+, Maastricht, The Netherlands.,School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Monique M Gerrits
- Department of Clinical Genetics, Maastricht University Medical Center+, Maastricht, The Netherlands.
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Campbell MJ. Tales from topographic oceans: topologically associated domains and cancer. Endocr Relat Cancer 2019; 26:R611-R626. [PMID: 31505466 PMCID: PMC7664306 DOI: 10.1530/erc-19-0348] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 09/09/2019] [Indexed: 01/03/2023]
Abstract
The 3D organization of the genome within the cell nucleus has come into sharp focus over the last decade. This has largely arisen because of the application of genomic approaches that have revealed numerous levels of genomic and chromatin interactions, including topologically associated domains (TADs). The current review examines how these domains were identified, are organized, how their boundaries arise and are regulated, and how genes within TADs are coordinately regulated. There are many examples of the disruption to TAD structure in cancer and the altered regulation, structure and function of TADs are discussed in the context of hormone responsive cancers, including breast, prostate and ovarian cancer. Finally, some aspects of the statistical insight and computational skills required to interrogate TAD organization are considered and future directions discussed.
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Affiliation(s)
- Moray J Campbell
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
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32
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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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33
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Wang ET, Treacy D, Eichinger K, Struck A, Estabrook J, Olafson H, Wang TT, Bhatt K, Westbrook T, Sedehizadeh S, Ward A, Day J, Brook D, Berglund JA, Cooper T, Housman D, Thornton C, Burge C. Transcriptome alterations in myotonic dystrophy skeletal muscle and heart. Hum Mol Genet 2019; 28:1312-1321. [PMID: 30561649 DOI: 10.1093/hmg/ddy432] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/30/2018] [Accepted: 12/10/2018] [Indexed: 11/12/2022] Open
Abstract
Myotonic dystrophy (dystrophia myotonica, DM) is a multi-systemic disease caused by expanded CTG or CCTG microsatellite repeats. Characterized by symptoms in muscle, heart and central nervous system, among others, it is one of the most variable diseases known. A major pathogenic event in DM is the sequestration of muscleblind-like proteins by CUG or CCUG repeat-containing RNAs transcribed from expanded repeats, and differences in the extent of MBNL sequestration dependent on repeat length and expression level may account for some portion of the variability. However, many other cellular pathways are reported to be perturbed in DM, and the severity of specific disease symptoms varies among individuals. To help understand this variability and facilitate research into DM, we generated 120 RNASeq transcriptomes from skeletal and heart muscle derived from healthy and DM1 biopsies and autopsies. A limited number of DM2 and Duchenne muscular dystrophy samples were also sequenced. We analyzed splicing and gene expression, identified tissue-specific changes in RNA processing and uncovered transcriptome changes strongly correlating with muscle strength. We created a web resource at http://DMseq.org that hosts raw and processed transcriptome data and provides a lightweight, responsive interface that enables browsing of processed data across the genome.
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Affiliation(s)
- Eric T Wang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL, USA.,University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Daniel Treacy
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Katy Eichinger
- Department of Neurology, University of Rochester, Rochester, NY, USA
| | - Adam Struck
- Department of Biochemistry, University of Oregon, Eugene, OR, USA
| | - Joseph Estabrook
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL, USA.,University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Hailey Olafson
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL, USA.,University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Thomas T Wang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kirti Bhatt
- Department of Neurology, University of Rochester, Rochester, NY, USA
| | - Tony Westbrook
- School of Life Sciences, Queen's Medical Center, University of Nottingham, Nottingham, UK
| | - Sam Sedehizadeh
- School of Life Sciences, Queen's Medical Center, University of Nottingham, Nottingham, UK
| | - Amanda Ward
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA
| | - John Day
- Department of Neurology, Stanford University, Palo Alto, CA, USA
| | - David Brook
- School of Life Sciences, Queen's Medical Center, University of Nottingham, Nottingham, UK
| | - J Andrew Berglund
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL, USA.,University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA.,Department of Biochemistry, University of Oregon, Eugene, OR, USA
| | - Thomas Cooper
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - David Housman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Charles Thornton
- Department of Neurology, University of Rochester, Rochester, NY, USA
| | - Christopher Burge
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.,Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
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Légaré C, Overend G, Guay SP, Monckton DG, Mathieu J, Gagnon C, Bouchard L. DMPK gene DNA methylation levels are associated with muscular and respiratory profiles in DM1. NEUROLOGY-GENETICS 2019; 5:e338. [PMID: 31334355 PMCID: PMC6568328 DOI: 10.1212/nxg.0000000000000338] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 12/03/2022]
Abstract
Objective To assess the effects of dystrophia myotonica protein kinase (DMPK) DNA methylation (DNAme) epivariation on muscular and respiratory profiles in patients with myotonic dystrophy type 1 (DM1). Methods Phenotypes were assessed with standardized measures. Pyrosequencing of bisulfite-treated DNA was used to quantify DNAme levels in blood from 90 patients with DM1 (adult form). Modal CTG repeat length was assessed using small-pool PCR. The presence of Acil-sensitive variant repeats was also tested. Results DNAme levels upstream of the CTG expansion (exon and intron 11) were correlated with modal CTG repeat length (rs = −0.224, p = 0.040; rs = −0.317, p = 0.003; and rs = −0.241, p = 0.027), whereas correlations were observed with epivariations downstream of the CTG repeats (rs = 0.227; p = 0.037). The presence of a variant repeat was associated with higher DNAme levels at multiple CpG sites (up to 10% higher; p = 0.001). Stepwise multiple linear regression modeling showed that DNAme contributed significantly and independently to explain phenotypic variability in ankle dorsiflexor (3 CpGs: p = 0.001, 0.013, and 0.001), grip (p = 0.089), and pinch (p = 0.028) strengths and in forced vital capacity (2 CpGs: p = 0.002 and 0.021) and maximal inspiratory pressure (p = 0.012). Conclusions In addition to the CTG repeat length, DMPK epivariations independently explain phenotypic variability in DM1 and could thus improve prognostic accuracy for patients.
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Affiliation(s)
- Cécilia Légaré
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Gayle Overend
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Simon-Pierre Guay
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Darren G Monckton
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Jean Mathieu
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Cynthia Gagnon
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
| | - Luigi Bouchard
- Department of Biochemistry (C.L., S.-P.G., L.B.), Université de Sherbrooke, Sherbrooke; ECOGENE-21 Biocluster (C.L., S.-P.G., L.B.), Chicoutimi, Québec, Canada; Groupe de Recherche interdisciplinaire sur les maladies neuromusculaires (C.L., J.M., C.G., L.B.), Saguenay, Canada; Institute of Molecular (G.O., D.G.M.), Cell and Systems Biology, University of Glasgow, United Kingdom; and Centre de Recherche Charles-Le-Moyne-Saguenay-Lac-StJean sur les innovations en santé (J.M., C.G.), Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Canada
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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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36
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Meinke P, Hintze S, Limmer S, Schoser B. Myotonic Dystrophy-A Progeroid Disease? Front Neurol 2018; 9:601. [PMID: 30140252 PMCID: PMC6095001 DOI: 10.3389/fneur.2018.00601] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/06/2018] [Indexed: 12/27/2022] Open
Abstract
Myotonic dystrophies (DM) are slowly progressing multisystemic disorders caused by repeat expansions in the DMPK or CNBP genes. The multisystemic involvement in DM patients often reflects the appearance of accelerated aging. This is partly due to visible features such as cataracts, muscle weakness, and frontal baldness, but there are also less obvious features like cardiac arrhythmia, diabetes or hypogammaglobulinemia. These aging features suggest the hypothesis that DM could be a segmental progeroid disease. To identify the molecular cause of this characteristic appearance of accelerated aging we compare clinical features of DM to “typical” segmental progeroid disorders caused by mutations in DNA repair or nuclear envelope proteins. Furthermore, we characterize if this premature aging effect is also reflected on the cellular level in DM and investigate overlaps with “classical” progeroid disorders. To investigate the molecular similarities at the cellular level we use primary DM and control cell lines. This analysis reveals many similarities to progeroid syndromes linked to the nuclear envelope. Our comparison on both clinical and molecular levels argues for qualification of DM as a segmental progeroid disorder.
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Affiliation(s)
- Peter Meinke
- Friedrich-Baur-Institute at the Department of Neurology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Stefan Hintze
- Friedrich-Baur-Institute at the Department of Neurology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Sarah Limmer
- Friedrich-Baur-Institute at the Department of Neurology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Benedikt Schoser
- Friedrich-Baur-Institute at the Department of Neurology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
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37
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Thomas JD, Oliveira R, Sznajder ŁJ, Swanson MS. Myotonic Dystrophy and Developmental Regulation of RNA Processing. Compr Physiol 2018; 8:509-553. [PMID: 29687899 PMCID: PMC11323716 DOI: 10.1002/cphy.c170002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myotonic dystrophy (DM) is a multisystemic disorder caused by microsatellite expansion mutations in two unrelated genes leading to similar, yet distinct, diseases. DM disease presentation is highly variable and distinguished by differences in age-of-onset and symptom severity. In the most severe form, DM presents with congenital onset and profound developmental defects. At the molecular level, DM pathogenesis is characterized by a toxic RNA gain-of-function mechanism that involves the transcription of noncoding microsatellite expansions. These mutant RNAs disrupt key cellular pathways, including RNA processing, localization, and translation. In DM, these toxic RNA effects are predominantly mediated through the modulation of the muscleblind-like and CUGBP and ETR-3-like factor families of RNA binding proteins (RBPs). Dysfunction of these RBPs results in widespread RNA processing defects culminating in the expression of developmentally inappropriate protein isoforms in adult tissues. The tissue that is the focus of this review, skeletal muscle, is particularly sensitive to mutant RNA-responsive perturbations, as patients display a variety of developmental, structural, and functional defects in muscle. Here, we provide a comprehensive overview of DM1 and DM2 clinical presentation and pathology as well as the underlying cellular and molecular defects associated with DM disease onset and progression. Additionally, fundamental aspects of skeletal muscle development altered in DM are highlighted together with ongoing and potential therapeutic avenues to treat this muscular dystrophy. © 2018 American Physiological Society. Compr Physiol 8:509-553, 2018.
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Affiliation(s)
- James D. Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Ruan Oliveira
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Łukasz J. Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
| | - Maurice S. Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, Florida, USA
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38
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Spitalieri P, Talarico RV, Caioli S, Murdocca M, Serafino A, Girasole M, Dinarelli S, Longo G, Pucci S, Botta A, Novelli G, Zona C, Mango R, Sangiuolo F. Modelling the pathogenesis of Myotonic Dystrophy type 1 cardiac phenotype through human iPSC-derived cardiomyocytes. J Mol Cell Cardiol 2018; 118:95-109. [PMID: 29551391 DOI: 10.1016/j.yjmcc.2018.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/12/2018] [Accepted: 03/14/2018] [Indexed: 12/20/2022]
Abstract
Myotonic Dystrophy type 1 (DM1) is a multisystemic disease, autosomal dominant, caused by a CTG repeat expansion in DMPK gene. We assessed the appropriateness of patient-specific induced pluripotent stem cell-derived cardiomyocytes (CMs) as a model to recapitulate some aspects of the pathogenetic mechanism involving cardiac manifestations in DM1 patients. Once obtained in vitro, CMs have been characterized for their morphology and their functionality. CMs DM1 show intranuclear foci and transcript markers abnormally spliced respect to WT ones, as well as several irregularities in nuclear morphology, probably caused by an unbalanced lamin A/C ratio. Electrophysiological characterization evidences an abnormal profile only in CMs DM1 such that the administration of antiarrythmic drugs to these cells highlights even more the functional defect linked to the disease. Finally, Atomic Force Measurements reveal differences in the biomechanical behaviour of CMs DM1, in terms of frequencies and synchronicity of the beats. Altogether the complex phenotype described in this work, strongly reproduces some aspects of the human DM1 cardiac phenotype. Therefore, the present study provides an in vitro model suggesting novel insights into the mechanisms leading to the development of arrhythmogenesis and dilatative cardiomyopathy to consider when approaching to DM1 patients, especially for the risk assessment of sudden cardiac death (SCD). These data could be also useful in identifying novel biomarkers effective in clinical settings and patient-tailored therapies.
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Affiliation(s)
- Paola Spitalieri
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Rosa V Talarico
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | | | - Michela Murdocca
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | | | | | | | | | - Sabina Pucci
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Annalisa Botta
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Giuseppe Novelli
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy
| | - Cristina Zona
- I.R.C.C.S. S. Lucia, Rome, Italy; Dept of Systems Medicine, University of Rome "Tor Vergata", Rome, Italy
| | | | - Federica Sangiuolo
- Dept of Biomedicine and Prevention, University of Rome "Tor Vergata", Rome, Italy.
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39
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Santoro M, Fontana L, Maiorca F, Centofanti F, Massa R, Silvestri G, Novelli G, Botta A. Expanded [CCTG]n repetitions are not associated with abnormal methylation at the CNBP locus in myotonic dystrophy type 2 (DM2) patients. Biochim Biophys Acta Mol Basis Dis 2018; 1864:917-924. [DOI: 10.1016/j.bbadis.2017.12.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 12/21/2017] [Accepted: 12/28/2017] [Indexed: 01/10/2023]
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40
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The Chromatin Remodeler Isw1 Prevents CAG Repeat Expansions During Transcription in Saccharomyces cerevisiae. Genetics 2018; 208:963-976. [PMID: 29305386 PMCID: PMC5844344 DOI: 10.1534/genetics.117.300529] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 01/02/2018] [Indexed: 12/23/2022] Open
Abstract
CAG/CTG trinucleotide repeat expansions cause several degenerative neurological and muscular diseases. Koch et al. show that the chromatin remodeling... CAG/CTG trinucleotide repeats are unstable sequences that are difficult to replicate, repair, and transcribe due to their structure-forming nature. CAG repeats strongly position nucleosomes; however, little is known about the chromatin remodeling needed to prevent repeat instability. In a Saccharomyces cerevisiae model system with CAG repeats carried on a YAC, we discovered that the chromatin remodeler Isw1 is required to prevent CAG repeat expansions during transcription. CAG repeat expansions in the absence of Isw1 were dependent on both transcription-coupled repair (TCR) and base-excision repair (BER). Furthermore, isw1∆ mutants are sensitive to methyl methanesulfonate (MMS) and exhibit synergistic MMS sensitivity when combined with BER or TCR pathway mutants. We conclude that CAG expansions in the isw1∆ mutant occur during a transcription-coupled excision repair process that involves both TCR and BER pathways. We observed increased RNA polymerase II (RNAPII) occupancy at the CAG repeat when transcription of the repeat was induced, but RNAPII binding did not change in isw1∆ mutants, ruling out a role for Isw1 remodeling in RNAPII progression. However, nucleosome occupancy over a transcribed CAG tract was altered in isw1∆ mutants. Based on the known role of Isw1 in the reestablishment of nucleosomal spacing after transcription, we suggest that a defect in this function allows DNA structures to form within repetitive DNA tracts, resulting in inappropriate excision repair and repeat-length changes. These results establish a new function for Isw1 in directly maintaining the chromatin structure at the CAG repeat, thereby limiting expansions that can occur during transcription-coupled excision repair.
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41
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Nakamori M, Hamanaka K, Thomas JD, Wang ET, Hayashi YK, Takahashi MP, Swanson MS, Nishino I, Mochizuki H. Aberrant Myokine Signaling in Congenital Myotonic Dystrophy. Cell Rep 2017; 21:1240-1252. [PMID: 29091763 PMCID: PMC5689469 DOI: 10.1016/j.celrep.2017.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/02/2017] [Accepted: 10/04/2017] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy types 1 (DM1) and 2 (DM2) are dominantly inherited neuromuscular disorders caused by a toxic gain of function of expanded CUG and CCUG repeats, respectively. Although both disorders are clinically similar, congenital myotonic dystrophy (CDM), a severe DM form, is found only in DM1. CDM is also characterized by muscle fiber immaturity not observed in adult DM, suggesting specific pathological mechanisms. Here, we revealed upregulation of the interleukin-6 (IL-6) myokine signaling pathway in CDM muscles. We also found a correlation between muscle immaturity and not only IL-6 expression but also expanded CTG repeat length and CpG methylation status upstream of the repeats. Aberrant CpG methylation was associated with transcriptional dysregulation at the repeat locus, increasing the toxic RNA burden that upregulates IL-6. Because the IL-6 pathway is involved in myocyte maturation and muscle atrophy, our results indicate that enhanced RNA toxicity contributes to severe CDM phenotypes through aberrant IL-6 signaling.
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Affiliation(s)
- Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan.
| | - Kohei Hamanaka
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - James D Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Gainesville, FL 32610, USA
| | - Yukiko K Hayashi
- Department of Pathophysiology, Tokyo Medical University, Shinjuku, Tokyo 160-0022, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan; Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - 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
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo 187-8502, Japan
| | - Hideki Mochizuki
- Department of Neurology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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Thomas JD, Sznajder ŁJ, Bardhi O, Aslam FN, Anastasiadis ZP, Scotti MM, Nishino I, Nakamori M, Wang ET, Swanson MS. Disrupted prenatal RNA processing and myogenesis in congenital myotonic dystrophy. Genes Dev 2017; 31:1122-1133. [PMID: 28698297 PMCID: PMC5538435 DOI: 10.1101/gad.300590.117] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 05/26/2017] [Indexed: 02/06/2023]
Abstract
Thomas et al. demonstrate that RNA misprocessing is a major pathogenic factor in congenital myotonic dystrophy and provide novel mouse models to further examine roles for cotranscriptional/post-transcriptional gene regulation during tissue development. Myotonic dystrophy type 1 (DM1) is a CTG microsatellite expansion (CTGexp) disorder caused by expression of CUGexp RNAs. These mutant RNAs alter the activities of RNA processing factors, including MBNL proteins, leading to re-expression of fetal isoforms in adult tissues and DM1 pathology. While this pathogenesis model accounts for adult-onset disease, the molecular basis of congenital DM (CDM) is unknown. Here, we test the hypothesis that disruption of developmentally regulated RNA alternative processing pathways contributes to CDM disease. We identify prominent alternative splicing and polyadenylation abnormalities in infant CDM muscle, and, although most are also misregulated in adult-onset DM1, dysregulation is significantly more severe in CDM. Furthermore, analysis of alternative splicing during human myogenesis reveals that CDM-relevant exons undergo prenatal RNA isoform transitions and are predicted to be disrupted by CUGexp-associated mechanisms in utero. To test this possibility and the contribution of MBNLs to CDM pathogenesis, we generated mouse Mbnl double (Mbnl1; Mbnl2) and triple (Mbnl1; Mbnl2; Mbnl3) muscle-specific knockout models that recapitulate the congenital myopathy, gene expression, and spliceopathy defects characteristic of CDM. This study demonstrates that RNA misprocessing is a major pathogenic factor in CDM and provides novel mouse models to further examine roles for cotranscriptional/post-transcriptional gene regulation during development.
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Affiliation(s)
- James D Thomas
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Łukasz J Sznajder
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Olgert Bardhi
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Faaiq N Aslam
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Zacharias P Anastasiadis
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Marina M Scotti
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Center of Neurology and Psychiatry, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Eric T Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
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Abstract
Eukaryotic genomes contain many repetitive DNA sequences that exhibit size instability. Some repeat elements have the added complication of being able to form secondary structures, such as hairpin loops, slipped DNA, triplex DNA or G-quadruplexes. Especially when repeat sequences are long, these DNA structures can form a significant impediment to DNA replication and repair, leading to DNA nicks, gaps, and breaks. In turn, repair or replication fork restart attempts within the repeat DNA can lead to addition or removal of repeat elements, which can sometimes lead to disease. One important DNA repair mechanism to maintain genomic integrity is recombination. Though early studies dismissed recombination as a mechanism driving repeat expansion and instability, recent results indicate that mitotic recombination is a key pathway operating within repetitive DNA. The action is two-fold: first, it is an important mechanism to repair nicks, gaps, breaks, or stalled forks to prevent chromosome fragility and protect cell health; second, recombination can cause repeat expansions or contractions, which can be deleterious. In this review, we summarize recent developments that illuminate the role of recombination in maintaining genome stability at DNA repeats.
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Barbé L, Lanni S, López-Castel A, Franck S, Spits C, Keymolen K, Seneca S, Tomé S, Miron I, Letourneau J, Liang M, Choufani S, Weksberg R, Wilson MD, Sedlacek Z, Gagnon C, Musova Z, Chitayat D, Shannon P, Mathieu J, Sermon K, Pearson CE. CpG Methylation, a Parent-of-Origin Effect for Maternal-Biased Transmission of Congenital Myotonic Dystrophy. Am J Hum Genet 2017; 100:488-505. [PMID: 28257691 PMCID: PMC5339342 DOI: 10.1016/j.ajhg.2017.01.033] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/26/2017] [Indexed: 12/13/2022] Open
Abstract
CTG repeat expansions in DMPK cause myotonic dystrophy (DM1) with a continuum of severity and ages of onset. Congenital DM1 (CDM1), the most severe form, presents distinct clinical features, large expansions, and almost exclusive maternal transmission. The correlation between CDM1 and expansion size is not absolute, suggesting contributions of other factors. We determined CpG methylation flanking the CTG repeat in 79 blood samples from 20 CDM1-affected individuals; 21, 27, and 11 individuals with DM1 but not CDM1 (henceforth non-CDM1) with maternal, paternal, and unknown inheritance; and collections of maternally and paternally derived chorionic villus samples (7 CVSs) and human embryonic stem cells (4 hESCs). All but two CDM1-affected individuals showed high levels of methylation upstream and downstream of the repeat, greater than non-CDM1 individuals (p = 7.04958 × 10−12). Most non-CDM1 individuals were devoid of methylation, where one in six showed downstream methylation. Only two non-CDM1 individuals showed upstream methylation, and these were maternally derived childhood onset, suggesting a continuum of methylation with age of onset. Only maternally derived hESCs and CVSs showed upstream methylation. In contrast, paternally derived samples (27 blood samples, 3 CVSs, and 2 hESCs) never showed upstream methylation. CTG tract length did not strictly correlate with CDM1 or methylation. Thus, methylation patterns flanking the CTG repeat are stronger indicators of CDM1 than repeat size. Spermatogonia with upstream methylation may not survive due to methylation-induced reduced expression of the adjacent SIX5, thereby protecting DM1-affected fathers from having CDM1-affected children. Thus, DMPK methylation may account for the maternal bias for CDM1 transmission, larger maternal CTG expansions, age of onset, and clinical continuum, and may serve as a diagnostic indicator.
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Santoro M, Masciullo M, Silvestri G, Novelli G, Botta A. Myotonic dystrophy type 1: role of CCG, CTC and CGG interruptions within DMPK alleles in the pathogenesis and molecular diagnosis. Clin Genet 2017; 92:355-364. [PMID: 27991661 DOI: 10.1111/cge.12954] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/09/2016] [Accepted: 12/12/2016] [Indexed: 12/12/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystem neuromuscular disease caused by a CTG triplet expansion in the 3'-untranslated region (3'-UTR) of DMPK gene. This CTG array is usually uninterrupted in both healthy and DM1 patients, but recent studies identified pathological variant expansions containing unstable CCG, CTC and CGG interruptions with a prevalence of 3-5% of cases. In this review, we will describe the clinical, molecular and genetic issues related to the occurrence of variant expansions associated with DM1. Indeed, the identification of these complex DMPK alleles leads to practical consequences in DM1 genetic counseling and testing, because these exams can give false negative results. Moreover, DM1 patients carrying interrupted alleles can manifest either additional atypical neurological symptoms or, conversely, mild, late-onset forms. Therefore, the prognosis of the disease in these patients is difficult to determine because of the great uncertainty about the genotype-phenotype correlations. We will discuss the putative effects of the variant DM1 alleles on the pathogenic disease mechanisms, including mitotic and meiotic repeats instability and splicing alteration typical of DM1 tissues. Interruptions within the DMPK expanded alleles could also interfere with the chromatin structure, the transcriptional activity of the DM1 locus and the interaction with RNA CUG-binding proteins.
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Affiliation(s)
- M Santoro
- Department of Neuroscience, Fondazione Don Carlo Gnocchi, Milan, Italy
| | - M Masciullo
- SPInal REhabilitation Lab, Fondazione Santa Lucia IRCCS, Rome, Italy
| | - G Silvestri
- Institute of Neurology, Fondazione Policlinico 'Gemelli', Rome, Italy
| | - G Novelli
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
| | - A Botta
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
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46
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Ueki J, Nakamori M, Nakamura M, Nishikawa M, Yoshida Y, Tanaka A, Morizane A, Kamon M, Araki T, Takahashi MP, Watanabe A, Inagaki N, Sakurai H. Myotonic dystrophy type 1 patient-derived iPSCs for the investigation of CTG repeat instability. Sci Rep 2017; 7:42522. [PMID: 28211918 PMCID: PMC5304155 DOI: 10.1038/srep42522] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/09/2017] [Indexed: 02/08/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal-dominant multi-system disease caused by expanded CTG repeats in dystrophia myotonica protein kinase (DMPK). The expanded CTG repeats are unstable and can increase the length of the gene with age, which worsens the symptoms. In order to establish a human stem cell system suitable for the investigation of repeat instability, DM1 patient-derived iPSCs were generated and differentiated into three cell types commonly affected in DM1, namely cardiomyocytes, neurons and myocytes. Then we precisely analysed the CTG repeat lengths in these cells. Our DM1-iPSCs showed a gradual lengthening of CTG repeats with unchanged repeat distribution in all cell lines depending on the passage numbers of undifferentiated cells. However, the average CTG repeat length did not change significantly after differentiation into different somatic cell types. We also evaluated the chromatin accessibility in DM1-iPSCs using ATAC-seq. The chromatin status in DM1 cardiomyocytes was closed at the DMPK locus as well as at SIX5 and its promoter region, whereas it was open in control, suggesting that the epigenetic modifications may be related to the CTG repeat expansion in DM1. These findings may help clarify the role of repeat instability in the CTG repeat expansion in DM1.
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Affiliation(s)
- Junko Ueki
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.,Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masahiro Nakamura
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Misato Nishikawa
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yoshinori Yoshida
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Azusa Tanaka
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Asuka Morizane
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masayoshi Kamon
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Toshiyuki Araki
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akira Watanabe
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hidetoshi Sakurai
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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Carrell ST, Carrell EM, Auerbach D, Pandey SK, Bennett CF, Dirksen RT, Thornton CA. Dmpk gene deletion or antisense knockdown does not compromise cardiac or skeletal muscle function in mice. Hum Mol Genet 2016; 25:4328-4338. [PMID: 27522499 DOI: 10.1093/hmg/ddw266] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/27/2016] [Accepted: 07/29/2016] [Indexed: 11/13/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a genetic disorder in which dominant-active DM protein kinase (DMPK) transcripts accumulate in nuclear foci, leading to abnormal regulation of RNA processing. A leading approach to treat DM1 uses DMPK-targeting antisense oligonucleotides (ASOs) to reduce levels of toxic RNA. However, basal levels of DMPK protein are reduced by half in DM1 patients. This raises concern that intolerance for further DMPK loss may limit ASO therapy, especially since mice with Dmpk gene deletion reportedly show cardiac defects and skeletal myopathy. We re-examined cardiac and muscle function in mice with Dmpk gene deletion, and studied post-maturity knockdown using Dmpk-targeting ASOs in mice with heterozygous deletion. Contrary to previous reports, we found no effect of Dmpk gene deletion on cardiac or muscle function, when studied on two genetic backgrounds. In heterozygous knockouts, the administration of ASOs reduced Dmpk expression in cardiac and skeletal muscle by > 90%, yet survival, electrocardiogram intervals, cardiac ejection fraction and muscle strength remained normal. The imposition of cardiac stress by pressure overload, or muscle stress by myotonia, did not unmask a requirement for DMPK. Our results support the feasibility and safety of using ASOs for post-transcriptional silencing of DMPK in muscle and heart.
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Affiliation(s)
| | | | | | | | | | | | - Charles A Thornton
- Department of Neurology, University of Rochester, Rochester, New York, NY, USA and
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Absence of MutSβ leads to the formation of slipped-DNA for CTG/CAG contractions at primate replication forks. DNA Repair (Amst) 2016; 42:107-18. [PMID: 27155933 DOI: 10.1016/j.dnarep.2016.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/22/2016] [Accepted: 04/05/2016] [Indexed: 11/22/2022]
Abstract
Typically disease-causing CAG/CTG repeats expand, but rare affected families can display high levels of contraction of the expanded repeat amongst offspring. Understanding instability is important since arresting expansions or enhancing contractions could be clinically beneficial. The MutSβ mismatch repair complex is required for CAG/CTG expansions in mice and patients. Oddly, by unknown mechanisms MutSβ-deficient mice incur contractions instead of expansions. Replication using CTG or CAG as the lagging strand template is known to cause contractions or expansions respectively; however, the interplay between replication and repair leading to this instability remains unclear. Towards understanding how repeat contractions may arise, we performed in vitro SV40-mediated replication of repeat-containing plasmids in the presence or absence of mismatch repair. Specifically, we separated repair from replication: Replication mediated by MutSβ- and MutSα-deficient human cells or cell extracts produced slipped-DNA heteroduplexes in the contraction- but not expansion-biased replication direction. Replication in the presence of MutSβ disfavoured the retention of replication products harbouring slipped-DNA heteroduplexes. Post-replication repair of slipped-DNAs by MutSβ-proficient extracts eliminated slipped-DNAs. Thus, a MutSβ-deficiency likely enhances repeat contractions because MutSβ protects against contractions by repairing template strand slip-outs. Replication deficient in LigaseI or PCNA-interaction mutant LigaseI revealed slipped-DNA formation at lagging strands. Our results reveal that distinct mechanisms lead to expansions or contractions and support inhibition of MutSβ as a therapeutic strategy to enhance the contraction of expanded repeats.
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Six Serum miRNAs Fail to Validate as Myotonic Dystrophy Type 1 Biomarkers. PLoS One 2016; 11:e0150501. [PMID: 26919350 PMCID: PMC4769077 DOI: 10.1371/journal.pone.0150501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 02/16/2016] [Indexed: 11/19/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic disease caused by expansion of a CTG microsatellite in the 3' untranslated region of the DMPK gene. Despite characteristic muscular, cardiac, and neuropsychological symptoms, CTG trinucleotide repeats are unstable both in the somatic and germinal lines, making the age of onset, clinical presentation, and disease severity very variable. A molecular biomarker to stratify patients and to follow disease progression is, thus, an unmet medical need. Looking for a novel biomarker, and given that specific miRNAs have been found to be misregulated in DM1 heart and muscle tissues, we profiled the expression of 175 known serum miRNAs in DM1 samples. The differences detected between patients and controls were less than 2.6 fold for all of them and a selection of six candidate miRNAs, miR-103, miR-107, miR-21, miR-29a, miR-30c, and miR-652 all failed to show consistent differences in serum expression in subsequent validation experiments.
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50
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Buckley L, Lacey M, Ehrlich M. Epigenetics of the myotonic dystrophy-associated DMPK gene neighborhood. Epigenomics 2016; 8:13-31. [PMID: 26756355 PMCID: PMC4863877 DOI: 10.2217/epi.15.104] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aim: Identify epigenetic marks in the vicinity of DMPK (linked to myotonic dystrophy, DM1) that help explain tissue-specific differences in its expression. Materials & methods: At DMPK and its flanking genes (DMWD, SIX5, BHMG1 and RSPH6A), we analyzed many epigenetic and transcription profiles from myoblasts, myotubes, skeletal muscle, heart and 30 nonmuscle samples. Results: In the DMPK gene neighborhood, muscle-associated DNA hypermethylation and hypomethylation, enhancer chromatin, and CTCF binding were seen. Myogenic DMPK hypermethylation correlated with high expression and decreased alternative promoter usage. Testis/sperm hypomethylation of BHMG1 and RSPH6A was associated with testis-specific expression. G-quadruplex (G4) motifs and sperm-specific hypomethylation were found near the DM1-linked CTG repeats within DMPK. Conclusion: Tissue-specific epigenetic features in DMPK and neighboring genes help regulate its expression. G4 motifs in DMPK DNA and RNA might contribute to DM1 pathology.
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Affiliation(s)
- Lauren Buckley
- Human Genetics Program, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
| | - Michelle Lacey
- Tulane Cancer Center & Department of Mathematics, Tulane University, New Orleans, LA 70112, USA
| | - Melanie Ehrlich
- Human Genetics Program, Center for Bioinformatics & Genomics, Tulane Cancer Center, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
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