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Lu J, Toro C, Adams DR, Moreno CAM, Lee WP, Leung YY, Harms MB, Vardarajan B, Heinzen EL. LUSTR: a new customizable tool for calling genome-wide germline and somatic short tandem repeat variants. BMC Genomics 2024; 25:115. [PMID: 38279154 PMCID: PMC10811831 DOI: 10.1186/s12864-023-09935-9] [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: 05/18/2023] [Accepted: 12/21/2023] [Indexed: 01/28/2024] Open
Abstract
BACKGROUND Short tandem repeats (STRs) are widely distributed across the human genome and are associated with numerous neurological disorders. However, the extent that STRs contribute to disease is likely under-estimated because of the challenges calling these variants in short read next generation sequencing data. Several computational tools have been developed for STR variant calling, but none fully address all of the complexities associated with this variant class. RESULTS Here we introduce LUSTR which is designed to address some of the challenges associated with STR variant calling by enabling more flexibility in defining STR loci, allowing for customizable modules to tailor analyses, and expanding the capability to call somatic and multiallelic STR variants. LUSTR is a user-friendly and easily customizable tool for targeted or unbiased genome-wide STR variant screening that can use either predefined or novel genome builds. Using both simulated and real data sets, we demonstrated that LUSTR accurately infers germline and somatic STR expansions in individuals with and without diseases. CONCLUSIONS LUSTR offers a powerful and user-friendly approach that allows for the identification of STR variants and can facilitate more comprehensive studies evaluating the role of pathogenic STR variants across human diseases.
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Affiliation(s)
- Jinfeng Lu
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- The Taub Institute for Research On Alzheimer's Disease and the Aging Brain, Gertrude H. Sergievsky Center, Department of Neurology, College of Physicians and Surgeons, Columbia University, The New York Presbyterian Hospital, New York, NY, 10032, USA.
| | - Camilo Toro
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health, Bethesda, MD, 20892, USA
| | - David R Adams
- NIH Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health, Bethesda, MD, 20892, USA
| | | | - Wan-Ping Lee
- Penn Neurodegeneration Genomics Center, Department of Pathology and Laboratory MedicinePerelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yuk Yee Leung
- Penn Neurodegeneration Genomics Center, Department of Pathology and Laboratory MedicinePerelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Mathew B Harms
- Department of Neurology, Division of Neuromuscular Medicine, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Badri Vardarajan
- The Taub Institute for Research On Alzheimer's Disease and the Aging Brain, Gertrude H. Sergievsky Center, Department of Neurology, College of Physicians and Surgeons, Columbia University, The New York Presbyterian Hospital, New York, NY, 10032, USA
| | - Erin L Heinzen
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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2
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Fan C, Chen K, Wang Y, Ball EV, Stenson PD, Mort M, Bacolla A, Kehrer-Sawatzki H, Tainer JA, Cooper DN, Zhao H. Profiling human pathogenic repeat expansion regions by synergistic and multi-level impacts on molecular connections. Hum Genet 2023; 142:245-274. [PMID: 36344696 PMCID: PMC10290229 DOI: 10.1007/s00439-022-02500-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/24/2022] [Indexed: 11/09/2022]
Abstract
Whilst DNA repeat expansions cause numerous heritable human disorders, their origins and underlying pathological mechanisms are often unclear. We collated a dataset comprising 224 human repeat expansions encompassing 203 different genes, and performed a systematic analysis with respect to key topological features at the DNA, RNA and protein levels. Comparison with controls without known pathogenicity and genomic regions lacking repeats, allowed the construction of the first tool to discriminate repeat regions harboring pathogenic repeat expansions (DPREx). At the DNA level, pathogenic repeat expansions exhibited stronger signals for DNA regulatory factors (e.g. H3K4me3, transcription factor-binding sites) in exons, promoters, 5'UTRs and 5'genes but were not significantly different from controls in introns, 3'UTRs and 3'genes. Additionally, pathogenic repeat expansions were also found to be enriched in non-B DNA structures. At the RNA level, pathogenic repeat expansions were characterized by lower free energy for forming RNA secondary structure and were closer to splice sites in introns, exons, promoters and 5'genes than controls. At the protein level, pathogenic repeat expansions exhibited a preference to form coil rather than other types of secondary structure, and tended to encode surface-located protein domains. Guided by these features, DPREx ( http://biomed.nscc-gz.cn/zhaolab/geneprediction/# ) achieved an Area Under the Curve (AUC) value of 0.88 in a test on an independent dataset. Pathogenic repeat expansions are thus located such that they exert a synergistic influence on the gene expression pathway involving inter-molecular connections at the DNA, RNA and protein levels.
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Affiliation(s)
- Cong Fan
- Department of Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, 107 Yan Jiang West Road, Guangzhou, 500001, People's Republic of China
| | - Ken Chen
- School of Computer Science and Engineering, Sun Yat-Sen University, Guangzhou, 500001, China
| | - Yukai Wang
- School of Life Science, Sun Yat-Sen University, Guangzhou, 500001, China
| | - Edward V Ball
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Peter D Stenson
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Matthew Mort
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Albino Bacolla
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, 6767 Bertner Avenue, Houston, TX, 77030, USA
| | | | - John A Tainer
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, 6767 Bertner Avenue, Houston, TX, 77030, USA
| | - David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Huiying Zhao
- Department of Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, 107 Yan Jiang West Road, Guangzhou, 500001, People's Republic of China.
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3
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Saha G, Ghosh S, Dubey VK, Saudagar P. Gene Alterations Induced by Glutamine (Q) Encoding CAG Repeats Associated with Neurodegeneration. Methods Mol Biol 2023; 2575:3-23. [PMID: 36301468 DOI: 10.1007/978-1-0716-2716-7_1] [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] [Indexed: 06/16/2023]
Abstract
Several studies have been reported linking the role of polyglutamine (polyQ) disease-associated proteins with altered gene regulation induced by an unstable trinucleotide (CAG) repeat. Owing to their dynamic nature of expansion, these DNA repeats form secondary structures interfering with the normal cellular mechanisms like replication and transcription and, thereby, have become the underlying cause of numerous neurodegenerative disorders involving mental retardation and/or muscular or neuronal degeneration. Despite the widespread expression of the disease-causing protein, specific subsets of neurons are susceptible to specific patterns of inheritance and clinical symptoms. Although this cell-type selectivity is still elusive and less understood, it has been found that aberrant transcriptional regulation is one of the primary causes of polyQ diseases where the functions of histone-modifying complexes are disrupted. Besides, epigenetic modifications play a critical role in the pathogenesis of these diseases. In this chapter, we will be delving into how these polyQ repeats induce the self-assembly and aggregation of altered carrier proteins based on gene alterations, causing neuronal toxicity and cellular deaths. Besides, genomic instability in CAG repeats due to altered chromatin-related enzymes will be highlighted, along with epigenetic changes present in many polyQ disorders. Understanding the underlying molecular mechanisms in the root cause of these disorders will culminate in identifying therapeutic approaches for the treatment of these neurodegenerative disorders.
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Affiliation(s)
- Gundappa Saha
- Department of Basic & Translational Sciences, Penn Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sukanya Ghosh
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Vikash Kumar Dubey
- School of Biochemical Engineering, Indian Institute of Technology BHU, Varanasi, Uttar Pradesh, India
| | - Prakash Saudagar
- Department of Biotechnology, National Institute of Technology, Warangal, Telangana, India.
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4
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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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5
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Deshmukh AL, Caron MC, Mohiuddin M, Lanni S, Panigrahi GB, Khan M, Engchuan W, Shum N, Faruqui A, Wang P, Yuen RKC, Nakamori M, Nakatani K, Masson JY, Pearson CE. FAN1 exo- not endo-nuclease pausing on disease-associated slipped-DNA repeats: A mechanism of repeat instability. Cell Rep 2021; 37:110078. [PMID: 34879276 DOI: 10.1016/j.celrep.2021.110078] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/02/2021] [Accepted: 11/09/2021] [Indexed: 12/19/2022] Open
Abstract
Ongoing inchworm-like CAG and CGG repeat expansions in brains, arising by aberrant processing of slipped DNAs, may drive Huntington's disease, fragile X syndrome, and autism. FAN1 nuclease modifies hyper-expansion rates by unknown means. We show that FAN1, through iterative cycles, binds, dimerizes, and cleaves slipped DNAs, yielding striking exo-nuclease pauses along slip-outs: 5'-C↓A↓GC↓A↓G-3' and 5'-C↓T↓G↓C↓T↓G-3'. CAG excision is slower than CTG and requires intra-strand A·A and T·T mismatches. Fully paired hairpins arrested excision, whereas disease-delaying CAA interruptions further slowed excision. Endo-nucleolytic cleavage is insensitive to slip-outs. Rare FAN1 variants are found in individuals with autism with CGG/CCG expansions, and CGG/CCG slip-outs show exo-nuclease pauses. The slip-out-specific ligand, naphthyridine-azaquinolone, which induces contractions of expanded repeats in vivo, requires FAN1 for its effect, and protects slip-outs from FAN1 exo-, but not endo-, nucleolytic digestion. FAN1's inchworm pausing of slip-out excision rates is well suited to modify inchworm expansion rates, which modify disease onset and progression.
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Affiliation(s)
- Amit Laxmikant Deshmukh
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Marie-Christine Caron
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, Québec City, QC G1R 3S3, Canada; Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec City, QC G1R 3S3, Canada
| | - Mohiuddin Mohiuddin
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Stella Lanni
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Gagan B Panigrahi
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Mahreen Khan
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Worrawat Engchuan
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Natalie Shum
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Aisha Faruqui
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Peixiang Wang
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Ryan K C Yuen
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Kazuhiko Nakatani
- Department of Regulatory Bioorganic Chemistry, the Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Division, Québec City, QC G1R 3S3, Canada; Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec City, QC G1R 3S3, Canada
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, PGCRL, Toronto, Canada, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada.
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6
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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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7
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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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8
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Ding D, Wang C, Chen Z, Xia K, Tang B, Qiu R, Jiang H. Polyglutamine-expanded ataxin3 alter specific gene expressions through changing DNA methylation status in SCA3/MJD. Aging (Albany NY) 2020; 13:3680-3698. [PMID: 33411688 PMCID: PMC7906150 DOI: 10.18632/aging.202331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/27/2020] [Indexed: 11/25/2022]
Abstract
DNA methylation has recently been linked to transcriptional dysregulation and neuronal dysfunction in polyglutamine (polyQ) disease. This study aims to determine whether (CAG)n expansion in ATXN3 perturbs DNA methylation status and affects gene expression. We analyzed DNA methylation throughout the genome using reduced representation bisulfite sequencing (RRBS) and confirmed the results using MethylTarget sequencing. Dynamic changes in DNA methylation, transcriptional and translational levels of specific genes were detected using BSP, qRT-PCR and western blot. In total, 135 differentially methylated regions (DMRs) were identified between SCA3/MJD and WT mouse cerebellum. KEGG analysis revealed differentially methylated genes involved in amino acid metabolism, Hedgehog signaling pathway, thyroid cancer, tumorigenesis and other pathways. We focused on DMRs that were directly associated with gene expression. On this basis, we further assessed 7 genes, including 13 DMRs, for DNA methylation validation and gene expression. We found that the methylation status of the DMRs of En1 and Nkx2-1 was negatively associated with their transcriptional and translational levels and that alteration of the DNA methylation status of DMRs and the corresponding transcription occurred before dyskinesia in SCA3/MJD mice. These results revealed novel DNA methylation-regulated genes, En1 and Nkx2-1, which may be useful for understanding the pathogenesis of SCA3/MJD.
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Affiliation(s)
- Dongxue Ding
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Chunrong Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Zhao Chen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Kun Xia
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China.,State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, P.R. China.,National Clinical Research Center for Geriatric Diseases, Changsha, Hunan, P. R. China
| | - Rong Qiu
- School of Information Science and Engineering, Central South University, Changsha, China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China.,State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, P.R. China.,National Clinical Research Center for Geriatric Diseases, Changsha, Hunan, P. R. China
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9
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Persi E, Wolf YI, Horn D, Ruppin E, Demichelis F, Gatenby RA, Gillies RJ, Koonin EV. Mutation-selection balance and compensatory mechanisms in tumour evolution. Nat Rev Genet 2020; 22:251-262. [PMID: 33257848 DOI: 10.1038/s41576-020-00299-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2020] [Indexed: 12/11/2022]
Abstract
Intratumour heterogeneity and phenotypic plasticity, sustained by a range of somatic aberrations, as well as epigenetic and metabolic adaptations, are the principal mechanisms that enable cancers to resist treatment and survive under environmental stress. A comprehensive picture of the interplay between different somatic aberrations, from point mutations to whole-genome duplications, in tumour initiation and progression is lacking. We posit that different genomic aberrations generally exhibit a temporal order, shaped by a balance between the levels of mutations and selective pressures. Repeat instability emerges first, followed by larger aberrations, with compensatory effects leading to robust tumour fitness maintained throughout the tumour progression. A better understanding of the interplay between genetic aberrations, the microenvironment, and epigenetic and metabolic cellular states is essential for early detection and prevention of cancer as well as development of efficient therapeutic strategies.
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Affiliation(s)
- Erez Persi
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA.
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - David Horn
- School of Physics and Astronomy, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Eytan Ruppin
- Cancer Data Science Lab, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Francesca Demichelis
- Department for Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy.,Caryl and Israel Englander Institute for Precision Medicine, New York Presbyterian Hospital, Weill Cornell Medicine, New York, NY, USA
| | - Robert A Gatenby
- Integrated Mathematical Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Robert J Gillies
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA.
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA.
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10
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Antisense Transcription across Nucleotide Repeat Expansions in Neurodegenerative and Neuromuscular Diseases: Progress and Mysteries. Genes (Basel) 2020; 11:genes11121418. [PMID: 33261024 PMCID: PMC7760973 DOI: 10.3390/genes11121418] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 12/14/2022] Open
Abstract
Unstable repeat expansions and insertions cause more than 30 neurodegenerative and neuromuscular diseases. Remarkably, bidirectional transcription of repeat expansions has been identified in at least 14 of these diseases. More remarkably, a growing number of studies has been showing that both sense and antisense repeat RNAs are able to dysregulate important cellular pathways, contributing together to the observed clinical phenotype. Notably, antisense repeat RNAs from spinocerebellar ataxia type 7, myotonic dystrophy type 1, Huntington's disease and frontotemporal dementia/amyotrophic lateral sclerosis associated genes have been implicated in transcriptional regulation of sense gene expression, acting either at a transcriptional or posttranscriptional level. The recent evidence that antisense repeat RNAs could modulate gene expression broadens our understanding of the pathogenic pathways and adds more complexity to the development of therapeutic strategies for these disorders. In this review, we cover the amazing progress made in the understanding of the pathogenic mechanisms associated with repeat expansion neurodegenerative and neuromuscular diseases with a focus on the impact of antisense repeat transcription in the development of efficient therapies.
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11
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Kovalenko M, Erdin S, Andrew MA, St Claire J, Shaughnessey M, Hubert L, Neto JL, Stortchevoi A, Fass DM, Mouro Pinto R, Haggarty SJ, Wilson JH, Talkowski ME, Wheeler VC. Histone deacetylase knockouts modify transcription, CAG instability and nuclear pathology in Huntington disease mice. eLife 2020; 9:55911. [PMID: 32990597 PMCID: PMC7581428 DOI: 10.7554/elife.55911] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 09/28/2020] [Indexed: 12/13/2022] Open
Abstract
Somatic expansion of the Huntington’s disease (HD) CAG repeat drives the rate of a pathogenic process ultimately resulting in neuronal cell death. Although mechanisms of toxicity are poorly delineated, transcriptional dysregulation is a likely contributor. To identify modifiers that act at the level of CAG expansion and/or downstream pathogenic processes, we tested the impact of genetic knockout, in HttQ111 mice, of Hdac2 or Hdac3 in medium-spiny striatal neurons that exhibit extensive CAG expansion and exquisite disease vulnerability. Both knockouts moderately attenuated CAG expansion, with Hdac2 knockout decreasing nuclear huntingtin pathology. Hdac2 knockout resulted in a substantial transcriptional response that included modification of transcriptional dysregulation elicited by the HttQ111 allele, likely via mechanisms unrelated to instability suppression. Our results identify novel modifiers of different aspects of HD pathogenesis in medium-spiny neurons and highlight a complex relationship between the expanded Htt allele and Hdac2 with implications for targeting transcriptional dysregulation in HD.
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Affiliation(s)
- Marina Kovalenko
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Serkan Erdin
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, United States
| | - Marissa A Andrew
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Jason St Claire
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | | | - Leroy Hubert
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
| | - João Luís Neto
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Alexei Stortchevoi
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Daniel M Fass
- Center for Genomic Medicine, Harvard Medical School, Boston, United States
| | - Ricardo Mouro Pinto
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Stephen J Haggarty
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - John H Wilson
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
| | - Michael E Talkowski
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Vanessa C Wheeler
- Center for Genomic Medicine, Harvard Medical School, Boston, United States.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, United States
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12
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Zhao H, Yang L, Dong Y, Wu ZY. Phenotypic variance in monozygotic twins with SCA3. Mol Genet Genomic Med 2020; 8:e1438. [PMID: 32729243 PMCID: PMC7549591 DOI: 10.1002/mgg3.1438] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/04/2020] [Accepted: 07/10/2020] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Spinocerebellar ataxia type 3 (SCA3) is a hereditary neurodegenerative disorder with high clinical heterogeneity. Twin study is valuable to estimate the contributions of gene and/or environment to phenotypic variance. However, SCA3 twins were extremely sparse and rarely reported. METHODS A pair of monozygotic twins with SCA3 was assessed using well-acknowledged scales. Genetic modifiers and methylation levels were determined by Sanger sequencing and pyrosequencing. RESULTS Sharing identical CAG repeat lengths, the twins presented with similar symptoms, whereas, the younger sister had an earlier age at onset of two years. The occurrence time and severity of constipation, blepharospasm and fasciculation were markedly different between the twins. Notable methylation level differences of several CpG sites existed between the twins. CONCLUSIONS It is the first time to report SCA3 monozygotic twin worldwide. The role of epigenetic factors in the phenotype variance deserved more attention. The DNA methylation may influence the phenotypic variance by altering the occurrence time and severity of symptoms, indicating its potential in alleviating the disease.
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Affiliation(s)
- Hua Zhao
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Lu Yang
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Dong
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhi-Ying Wu
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
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13
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Armstrong MJ, Jin Y, Allen EG, Jin P. Diverse and dynamic DNA modifications in brain and diseases. Hum Mol Genet 2020; 28:R241-R253. [PMID: 31348493 DOI: 10.1093/hmg/ddz179] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 12/17/2022] Open
Abstract
DNA methylation is a class of epigenetic modification essential for coordinating gene expression timing and magnitude throughout normal brain development and for proper brain function following development. Aberrant methylation changes are associated with changes in chromatin architecture, transcriptional alterations and a host of neurological disorders and diseases. This review highlights recent advances in our understanding of the methylome's functionality and covers potential new roles for DNA methylation, their readers, writers, and erasers. Additionally, we examine novel insights into the relationship between the methylome, DNA-protein interactions, and their contribution to neurodegenerative diseases. Lastly, we outline the gaps in our knowledge that will likely be filled through the widespread use of newer technologies that provide greater resolution into how individual cell types are affected by disease and the contribution of each individual modification site to disease pathogenicity.
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Affiliation(s)
- Matthew J Armstrong
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Yulin Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Emily G Allen
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, USA
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14
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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: 148] [Impact Index Per Article: 37.0] [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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15
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Chiara M, Zambelli F, Picardi E, Horner DS, Pesole G. Critical assessment of bioinformatics methods for the characterization of pathological repeat expansions with single-molecule sequencing data. Brief Bioinform 2019; 21:1971-1986. [DOI: 10.1093/bib/bbz099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/22/2019] [Accepted: 07/09/2019] [Indexed: 01/19/2023] Open
Abstract
Abstract
A number of studies have reported the successful application of single-molecule sequencing technologies to the determination of the size and sequence of pathological expanded microsatellite repeats over the last 5 years. However, different custom bioinformatics pipelines were employed in each study, preventing meaningful comparisons and somewhat limiting the reproducibility of the results. In this review, we provide a brief summary of state-of-the-art methods for the characterization of expanded repeats alleles, along with a detailed comparison of bioinformatics tools for the determination of repeat length and sequence, using both real and simulated data. Our reanalysis of publicly available human genome sequencing data suggests a modest, but statistically significant, increase of the error rate of single-molecule sequencing technologies at genomic regions containing short tandem repeats. However, we observe that all the methods herein tested, irrespective of the strategy used for the analysis of the data (either based on the alignment or assembly of the reads), show high levels of sensitivity in both the detection of expanded tandem repeats and the estimation of the expansion size, suggesting that approaches based on single-molecule sequencing technologies are highly effective for the detection and quantification of tandem repeat expansions and contractions.
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Affiliation(s)
- Matteo Chiara
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
| | - Federico Zambelli
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
| | - Ernesto Picardi
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari “A. Moro”, Via Orabona 4, 70126 Bari, Italy
| | - David S Horner
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
| | - Graziano Pesole
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Via Amendola e, 70126 Bari, Italy
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari “A. Moro”, Via Orabona 4, 70126 Bari, Italy
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16
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Patel D, Patel M, Datta S, Singh U. CGGBP1 regulates CTCF occupancy at repeats. Epigenetics Chromatin 2019; 12:57. [PMID: 31547883 PMCID: PMC6757366 DOI: 10.1186/s13072-019-0305-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 09/12/2019] [Indexed: 12/27/2022] Open
Abstract
Background CGGBP1 is a repeat-binding protein with diverse functions in the regulation of gene expression, cytosine methylation, repeat silencing and genomic integrity. CGGBP1 has also been identified as a cooperator of histone-modifying enzymes and as a component of CTCF-containing complexes that regulate the enhancer–promoter looping. CGGBP1–CTCF cross talk in chromatin regulation has been hitherto unknown. Results Here, we report that the occupancy of CTCF at repeats depends on CGGBP1. Using ChIP-sequencing for CTCF, we describe its occupancy at repetitive DNA. Our results show that endogenous level of CGGBP1 ensures CTCF occupancy preferentially on repeats over canonical CTCF motifs. By combining CTCF ChIP-sequencing results with ChIP sequencing for three different kinds of histone modifications (H3K4me3, H3K9me3 and H3K27me3), we show that the CGGBP1-dependent repeat-rich CTCF-binding sites regulate histone marks in flanking regions. Conclusion CGGBP1 affects the pattern of CTCF occupancy. Our results posit CGGBP1 as a regulator of CTCF and its binding sites in interspersed repeats.
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Affiliation(s)
- Divyesh Patel
- HoMeCell Lab, Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat, 382355, India
| | - Manthan Patel
- HoMeCell Lab, Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat, 382355, India
| | - Subhamoy Datta
- HoMeCell Lab, Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat, 382355, India
| | - Umashankar Singh
- HoMeCell Lab, Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat, 382355, India.
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17
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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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18
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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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19
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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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20
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Crowley JJ, Szatkiewicz J, Kähler AK, Giusti-Rodriguez P, Ancalade N, Booker JK, Carr MT JL, Crawford GE, Losh M, Stockmeier CA, Taylor AK, Piven J, Sullivan PF. Common-variant associations with fragile X syndrome. Mol Psychiatry 2019; 24:338-344. [PMID: 30531935 PMCID: PMC6457435 DOI: 10.1038/s41380-018-0290-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 10/07/2018] [Accepted: 10/09/2018] [Indexed: 12/15/2022]
Abstract
Fragile X syndrome is rare but a prominent cause of intellectual disability. It is usually caused by a de novo mutation that occurs on multiple haplotypes and thus would not be expected to be detectible using genome-wide association (GWA). We conducted GWA in 89 male FXS cases and 266 male controls, and detected multiple genome-wide significant signals near FMR1 (odds ratio = 8.10, P = 2.5 × 10-10). These findings withstood robust attempts at falsification. Fine-mapping yielded a minimum P = 1.13 × 10-14, but did not narrow the interval. Comprehensive functional genomic integration did not provide a mechanistic hypothesis. Controls carrying a risk haplotype had significantly longer FMR1 CGG repeats than controls with the protective haplotype (P = 4.75 × 10-5), which may predispose toward increases in CGG number to the premutation range over many generations. This is a salutary reminder of the complexity of even "simple" monogenetic disorders.
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Affiliation(s)
- James J Crowley
- Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
| | - Jin Szatkiewicz
- Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
| | - Anna K Kähler
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | | | - NaEshia Ancalade
- Department of Genetics, University of North Carolina at Chapel Hill, NC, USA
| | - Jessica K Booker
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, NC, USA
| | - Jennifer L Carr MT
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, NC, USA
| | | | - Molly Losh
- Department of Communication Sciences, Northwestern University, Evanston, IL, USA
| | | | | | - Joseph Piven
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. .,Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Patrick F Sullivan
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. .,Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. .,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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21
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Abu Diab M, Eiges R. The Contribution of Pluripotent Stem Cell (PSC)-Based Models to the Study of Fragile X Syndrome (FXS). Brain Sci 2019; 9:brainsci9020042. [PMID: 30769941 PMCID: PMC6406836 DOI: 10.3390/brainsci9020042] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 02/06/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common heritable form of cognitive impairment. It results from a deficiency in the fragile X mental retardation protein (FMRP) due to a CGG repeat expansion in the 5′-UTR of the X-linked FMR1 gene. When CGGs expand beyond 200 copies, they lead to epigenetic gene silencing of the gene. In addition, the greater the allele size, the more likely it will become unstable and exhibit mosaicism for expansion size between and within tissues in affected individuals. The timing and mechanisms of FMR1 epigenetic gene silencing and repeat instability are far from being understood given the lack of appropriate cellular and animal models that can fully recapitulate the molecular features characteristic of the disease pathogenesis in humans. This review summarizes the data collected to date from mutant human embryonic stem cells, induced pluripotent stem cells, and hybrid fusions, and discusses their contribution to the investigation of FXS, their key limitations, and future prospects.
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Affiliation(s)
- Manar Abu Diab
- Stem Cell Research Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center, Jerusalem 91031, Israel.
- School of Medicine, Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
| | - Rachel Eiges
- Stem Cell Research Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center, Jerusalem 91031, Israel.
- School of Medicine, Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
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22
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Costa IPD, Almeida BC, Sequeiros J, Amorim A, Martins S. A Pipeline to Assess Disease-Associated Haplotypes in Repeat Expansion Disorders: The Example of MJD/SCA3 Locus. Front Genet 2019; 10:38. [PMID: 30804982 PMCID: PMC6370646 DOI: 10.3389/fgene.2019.00038] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/18/2019] [Indexed: 12/13/2022] Open
Abstract
At least 40 human diseases are associated with repeat expansions; yet, the mutational origin and instability mechanisms remain unknown for most of them. Previously, genetic epidemiology and predisposing backgrounds for the instability of some expanding loci have been studied in different populations through the analysis of diversity flanking the respective pathogenic repeats. Here, we aimed at developing a pipeline to assess disease-associated haplotypes at oligonucleotide repeat loci, combining analysis of single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs). Machado-Joseph disease (MJD/SCA3), the most frequent dominant ataxia worldwide, was used as an example of a detailed procedure. Thus, to identify genetic backgrounds that segregate with expanded/mutated alleles in MJD, we selected a set of 26 SNPs and 7 STRs flanking the causative CAG repeat. Key criteria and steps for this selection are described, and included (1) haplotype blocks minimizing the occurrence of recombination (for SNPs); and (2) match scores to increase potential for polymorphic information content of repetitive sequences found in Tandem Repeats Finder (for STRs). To directly assess SNP haplotypes in phase with MJD expansions, we optimized a strategy with preferential amplification of normal over expanded alleles, in addition to SNP allele-specific amplifications; this allowed the identification of disease-associated SNP haplotypes, even when only the proband is available in a given family. To infer STR haplotypes, we optimized a multiplex PCR, including 7 STRs plus the MJD_CAG repeat, followed by analysis of segregation or the use of the PHASE software. This protocol is a ready-to-use tool to assess MJD haplotypes in different populations. The pipeline designed can be used to assess disease-associated haplotypes in other repeat-expansion diseases. This should be of great utility to study (1) genetic epidemiology (population-of-origin, age and spreading routes of mutations) and (2) mechanisms responsible for de novo expansions, in these neurological diseases; (3) to detect predisposing haplotypes and (4) phenotype modifiers; (5) to help solving cases of apparent homoallelism (two same-size normal alleles) in diagnosis; and (6) to identify the best targets for the development of allele-specific therapies in ethnically diverse patient populations.
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Affiliation(s)
- Inês P D Costa
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal
| | - Beatriz C Almeida
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.,Faculdade de Ciências da Universidade do Porto, Porto, Portugal
| | - Jorge Sequeiros
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - António Amorim
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.,Faculdade de Ciências da Universidade do Porto, Porto, Portugal
| | - Sandra Martins
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal
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23
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Yau WY, O'Connor E, Sullivan R, Akijian L, Wood NW. DNA repair in trinucleotide repeat ataxias. FEBS J 2018; 285:3669-3682. [PMID: 30152109 DOI: 10.1111/febs.14644] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/15/2018] [Accepted: 08/23/2018] [Indexed: 12/21/2022]
Abstract
The inherited cerebellar ataxias comprise of a genetic heterogeneous group of disorders. Pathogenic expansions of cytosine-adenine-guanine (CAG) encoding polyglutamine tracts account for the largest proportion of autosomal dominant cerebellar ataxias, while GAA expansion in the first introns of frataxin gene is the commonest cause of autosomal recessive cerebellar ataxias. Currently, there is no available treatment to alter the disease trajectory, with devastating consequences for affected individuals. Inter- and Intrafamily phenotypic variability suggest the existence of genetic modifiers, which may become targets amendable to treatment. Recent studies have demonstrated the importance of DNA repair pathways in modifying spinocerebellar ataxia with CAG repeat expansions. In this review, we discuss the mechanisms in which DNA repair pathways, epigenetics and other genetic factors may act as modifiers in cerebellar ataxias due to trinucleotide repeat expansions.
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Affiliation(s)
- Wai Yan Yau
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Emer O'Connor
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Roisin Sullivan
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK
| | - Layan Akijian
- Department of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK
| | - Nicholas W Wood
- Department of Molecular Neuroscience, Institute of Neurology, University College London, UK.,Neurogenetics laboratory, The National Hospital for Neurology and Neurosurgery, London, UK
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24
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Sun JH, Zhou L, Emerson DJ, Phyo SA, Titus KR, Gong W, Gilgenast TG, Beagan JA, Davidson BL, Tassone F, Phillips-Cremins JE. Disease-Associated Short Tandem Repeats Co-localize with Chromatin Domain Boundaries. Cell 2018; 175:224-238.e15. [PMID: 30173918 DOI: 10.1016/j.cell.2018.08.005] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/11/2018] [Accepted: 08/02/2018] [Indexed: 01/15/2023]
Abstract
More than 25 inherited human disorders are caused by the unstable expansion of repetitive DNA sequences termed short tandem repeats (STRs). A fundamental unresolved question is why some STRs are susceptible to pathologic expansion, whereas thousands of repeat tracts across the human genome are relatively stable. Here, we discover that nearly all disease-associated STRs (daSTRs) are located at boundaries demarcating 3D chromatin domains. We identify a subset of boundaries with markedly higher CpG island density compared to the rest of the genome. daSTRs specifically localize to ultra-high-density CpG island boundaries, suggesting they might be hotspots for epigenetic misregulation or topological disruption linked to STR expansion. Fragile X syndrome patients exhibit severe boundary disruption in a manner that correlates with local loss of CTCF occupancy and the degree of FMR1 silencing. Our data uncover higher-order chromatin architecture as a new dimension in understanding repeat expansion disorders.
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Affiliation(s)
- James H Sun
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Linda Zhou
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Genomics and Computational Biology Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel J Emerson
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sai A Phyo
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Katelyn R Titus
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wanfeng Gong
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Thomas G Gilgenast
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan A Beagan
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Beverly L Davidson
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, The University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Flora Tassone
- Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95616, USA; MIND Institute, UC Davis, Sacramento, CA 95616, USA
| | - Jennifer E Phillips-Cremins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA.
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25
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Tomé S, Dandelot E, Dogan C, Bertrand A, Geneviève D, Péréon Y, Simon M, Bonnefont JP, Bassez G, Gourdon G. Unusual association of a unique CAG interruption in 5' of DM1 CTG repeats with intergenerational contractions and low somatic mosaicism. Hum Mutat 2018; 39:970-982. [PMID: 29664219 DOI: 10.1002/humu.23531] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/23/2018] [Accepted: 04/10/2018] [Indexed: 11/11/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a dominant multisystemic disorder associated with high variability of symptoms and anticipation. DM1 is caused by an unstable CTG repeat expansion that usually increases in successive generations and tissues. DM1 family pedigrees have shown that ∼90% and 10% of transmissions result in expansions and contractions of the CTG repeat, respectively. To date, the mechanisms of CTG repeat contraction remain poorly documented in DM1. In this report, we identified two new DM1 families with apparent contractions and no worsening of DM1 symptoms in two and three successive maternal transmissions. A new and unique CAG interruption was found in 5' of the CTG expansion in one family, whereas multiple 5' CCG interruptions were detected in the second family. We showed that these interruptions are associated with maternal intergenerational contractions and low somatic mosaicism in blood. By specific triplet-prime PCR, we observed that CTG repeat changes (contractions/expansions) occur preferentially in 3' of the interruptions for both families.
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Affiliation(s)
- Stéphanie Tomé
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
| | - Elodie Dandelot
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
| | - Céline Dogan
- Neuromuscular Reference Center, AP-HP, Hôpital Pitié-Salpêtrière, F-75013, Paris, France
| | - Alexis Bertrand
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
| | - David Geneviève
- Molecular Genetic Laboratory, Necker Hospital, Paris, France.,Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, CHU Montpellier, Université Montpellier, Montpellier, France
| | - Yann Péréon
- Centre for Neuromuscular Diseases, Hôtel-Dieu Hospital, Nantes, France
| | -
- Pauline Arnaud: Department of genetic, Bichat Hospital, Paris, France, Raphaële Chasserieau: Centre for Neuromuscular Diseases, Hôtel-Dieu Hospital, Nantes, France, Pascal Cintas: Neuromuscular Reference Center, Purpan Hospital, Toulouse, France, Ana-maria Cobo Esteban: Neuromuscular Reference Center, Marin Hospital, Hendaye, France, Marie-Carmen Cruz: Neuromuscular Reference Center, Purpan Hospital, Toulouse, France, Dalil Hamroun: Centre Hospitalo-Universitaire de Montpellier, Montpellier, France, Armelle Magot: Neuromuscular Reference Center, Hôtel-Dieu Hospital, Nantes, France, Alexandra Nadaj-Pakleza Neuromuscular Reference Center, Larrey Hospital, Angers, France, Anne-catherine Aube-Gauthier Neuromuscular Reference Center, Larrey Hospital, Angers, France, Andoni Urtizberea: Neuromuscular Reference Center, Marin Hospital, Hendaye, France
| | - Marie Simon
- Molecular Genetic Laboratory, Necker Hospital, Paris, France
| | | | - Guillaume Bassez
- Sorbonne Université, Inserm, UMRS974, Neuromuscular Reference center, AP-HP, Hôpital Pitié-Salpêtrière, F-75013, Paris, France
| | - Geneviève Gourdon
- Laboratory CTGDM, Inserm UMR1163, Paris, France; Institut Imagine, Université Paris-Descartes-Sorbonne Paris-Cité, Paris, France
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26
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Abstract
Accumulating evidence suggests that many classes of DNA repeats exhibit attributes that distinguish them from other genetic variants, including the fact that they are more liable to mutation; this enables them to mediate genetic plasticity. The expansion of tandem repeats, particularly of short tandem repeats, can cause a range of disorders (including Huntington disease, various ataxias, motor neuron disease, frontotemporal dementia, fragile X syndrome and other neurological disorders), and emerging data suggest that tandem repeat polymorphisms (TRPs) can also regulate gene expression in healthy individuals. TRPs in human genomes may also contribute to the missing heritability of polygenic disorders. A better understanding of tandem repeats and their associated repeatome, as well as their capacity for genetic plasticity via both germline and somatic mutations, is needed to transform our understanding of the role of TRPs in health and disease.
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Affiliation(s)
- Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne.,Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
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27
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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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28
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Abstract
The dominant polyglutamine (polyQ) disorders are a group of progressive and incurable neurodegenerative disorders, which are caused by unstable expanded CAG trinucleotide repeats in the coding regions of their respective causative genes. The most prevalent polyQ disorders worldwide are Huntington’s disease and spinocerebellar ataxia type 3. Epigenetic mechanisms, such as DNA methylation, histone modifications and chromatin remodeling and noncoding RNA regulation, regulate gene expression or genome function. Epigenetic dysregulation has been suggested to play a pivotal role in the pathogenesis of polyQ disorders. Here, we summarize the current knowledge of epigenetic changes present in several representative polyQ disorders and discuss the potentiality of miRNAs as therapeutic targets for the clinic therapy of these disorders.
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Affiliation(s)
- Hongmei Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Tie-Shan Tang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Caixia Guo
- CAS Key Laboratory of Genomics & Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
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29
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Zu T, Cleary JD, Liu Y, Bañez-Coronel M, Bubenik JL, Ayhan F, Ashizawa T, Xia G, Clark HB, Yachnis AT, Swanson MS, Ranum LPW. RAN Translation Regulated by Muscleblind Proteins in Myotonic Dystrophy Type 2. Neuron 2017; 95:1292-1305.e5. [PMID: 28910618 DOI: 10.1016/j.neuron.2017.08.039] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 05/31/2017] [Accepted: 08/25/2017] [Indexed: 10/18/2022]
Abstract
Several microsatellite-expansion diseases are characterized by the accumulation of RNA foci and RAN proteins, raising the possibility of a mechanistic connection. We explored this question using myotonic dystrophy type 2, a multisystemic disease thought to be primarily caused by RNA gain-of-function effects. We demonstrate that the DM2 CCTG⋅CAGG expansion expresses sense and antisense tetrapeptide poly-(LPAC) and poly-(QAGR) RAN proteins, respectively. In DM2 autopsy brains, LPAC is found in neurons, astrocytes, and glia in gray matter, and antisense QAGR proteins accumulate within white matter. LPAC and QAGR proteins are toxic to cells independent of RNA gain of function. RNA foci and nuclear sequestration of CCUG transcripts by MBNL1 is inversely correlated with LPAC expression. These data suggest a model that involves nuclear retention of expansion RNAs by RNA-binding proteins (RBPs) and an acute phase in which expansion RNAs exceed RBP sequestration capacity, are exported to the cytoplasm, and undergo RAN translation. VIDEO ABSTRACT.
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Affiliation(s)
- Tao Zu
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - John D Cleary
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Yuanjing Liu
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Monica Bañez-Coronel
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Jodi L Bubenik
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Fatma Ayhan
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Tetsuo Ashizawa
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Neurology, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Neurological Institute, Houston Methodist Hospital, Houston, TX 77030, USA
| | - Guangbin Xia
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Neurology, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - H Brent Clark
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Anthony T Yachnis
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Maurice S Swanson
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA; Genetics Institute, University of Florida, Gainesville, FL 32610, USA
| | - Laura P W Ranum
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA; Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA; Department of Neurology, University of Florida, Gainesville, FL 32610, USA; Genetics Institute, University of Florida, Gainesville, FL 32610, USA.
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30
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Faruq M, Magaña JJ, Suroliya V, Narang A, Murillo-Melo NM, Hernández-Hernández O, Srivastava AK, Mukerji M. A Complete Association of an intronic SNP rs6798742 with Origin of Spinocerebellar Ataxia Type 7-CAG Expansion Loci in the Indian and Mexican Population. Ann Hum Genet 2017; 81:197-204. [DOI: 10.1111/ahg.12200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 04/27/2017] [Accepted: 05/15/2017] [Indexed: 11/28/2022]
Affiliation(s)
- Mohammed Faruq
- Genomics and Molecular Medicine; Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology (CSIR -IGIB); Mall Road Delhi India
| | - Jonathan J. Magaña
- Laboratory of Genomic Medicine, Department of Genetics; National Rehabilitation Institute-LGII (INR-LGII); Mexico City Mexico
| | - Varun Suroliya
- Department of Neurology, Neuroscience Centre; All India Institute of Medical Sciences; New Delhi India
| | - Ankita Narang
- Genomics and Molecular Medicine; Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology (CSIR -IGIB); Mall Road Delhi India
| | - Nadia M. Murillo-Melo
- Laboratory of Genomic Medicine, Department of Genetics; National Rehabilitation Institute-LGII (INR-LGII); Mexico City Mexico
| | - Oscar Hernández-Hernández
- Laboratory of Genomic Medicine, Department of Genetics; National Rehabilitation Institute-LGII (INR-LGII); Mexico City Mexico
| | - Achal K. Srivastava
- Department of Neurology, Neuroscience Centre; All India Institute of Medical Sciences; New Delhi India
| | - Mitali Mukerji
- Genomics and Molecular Medicine; Council of Scientific and Industrial Research-Institute of Genomics and Integrative Biology (CSIR -IGIB); Mall Road Delhi India
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31
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Wang C, Peng H, Li J, Ding D, Chen Z, Long Z, Peng Y, Zhou X, Ye W, Li K, Xu Q, Ai S, Song C, Weng L, Qiu R, Xia K, Tang B, Jiang H. Alteration of methylation status in the ATXN3 gene promoter region is linked to the SCA3/MJD. Neurobiol Aging 2017; 53:192.e5-192.e10. [DOI: 10.1016/j.neurobiolaging.2016.12.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 11/14/2016] [Accepted: 12/11/2016] [Indexed: 12/13/2022]
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32
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Madireddy A, Gerhardt J. Replication Through Repetitive DNA Elements and Their Role in Human Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:549-581. [PMID: 29357073 DOI: 10.1007/978-981-10-6955-0_23] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Human cells contain various repetitive DNA sequences, which can be a challenge for the DNA replication machinery to travel through and replicate correctly. Repetitive DNA sequence can adopt non-B DNA structures, which could block the DNA replication. Prolonged stalling of the replication fork at the endogenous repeats in human cells can have severe consequences such as genome instability that includes repeat expansions, contractions, and chromosome fragility. Several neurological and muscular diseases are caused by a repeat expansion. Furthermore genome instability is the major cause of cancer. This chapter describes some of the important classes of repetitive DNA sequences in the mammalian genome, their ability to form secondary DNA structures, their contribution to replication fork stalling, and models for repeat expansion as well as chromosomal fragility. Included in this chapter are also some of the strategies currently employed to detect changes in DNA replication and proteins that could prevent the repeat-mediated disruption of DNA replication in human cells. Additionally summarized are the consequences of repeat-associated perturbation of the DNA replication, which could lead to specific human diseases.
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33
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Genetic Contributors to Intergenerational CAG Repeat Instability in Huntington's Disease Knock-In Mice. Genetics 2016; 205:503-516. [PMID: 27913616 PMCID: PMC5289832 DOI: 10.1534/genetics.116.195578] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/12/2016] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of a CAG trinucleotide repeat in exon 1 of the HTT gene. Longer repeat sizes are associated with increased disease penetrance and earlier ages of onset. Intergenerationally unstable transmissions are common in HD families, partly underlying the genetic anticipation seen in this disorder. HD CAG knock-in mouse models also exhibit a propensity for intergenerational repeat size changes. In this work, we examine intergenerational instability of the CAG repeat in over 20,000 transmissions in the largest HD knock-in mouse model breeding datasets reported to date. We confirmed previous observations that parental sex drives the relative ratio of expansions and contractions. The large datasets further allowed us to distinguish effects of paternal CAG repeat length on the magnitude and frequency of expansions and contractions, as well as the identification of large repeat size jumps in the knock-in models. Distinct degrees of intergenerational instability were observed between knock-in mice of six background strains, indicating the occurrence of trans-acting genetic modifiers. We also found that lines harboring a neomycin resistance cassette upstream of Htt showed reduced expansion frequency, indicative of a contributing role for sequences in cis, with the expanded repeat as modifiers of intergenerational instability. These results provide a basis for further understanding of the mechanisms underlying intergenerational repeat instability.
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34
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Grzybek M, Golonko A, Walczak M, Lisowski P. Epigenetics of cell fate reprogramming and its implications for neurological disorders modelling. Neurobiol Dis 2016; 99:84-120. [PMID: 27890672 DOI: 10.1016/j.nbd.2016.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 11/03/2016] [Accepted: 11/21/2016] [Indexed: 02/06/2023] Open
Abstract
The reprogramming of human induced pluripotent stem cells (hiPSCs) proceeds in a stepwise manner with reprogramming factors binding and epigenetic composition changes during transition to maintain the epigenetic landscape, important for pluripotency. There arises a question as to whether the aberrant epigenetic state after reprogramming leads to epigenetic defects in induced stem cells causing unpredictable long term effects in differentiated cells. In this review, we present a comprehensive view of epigenetic alterations accompanying reprogramming, cell maintenance and differentiation as factors that influence applications of hiPSCs in stem cell based technologies. We conclude that sample heterogeneity masks DNA methylation signatures in subpopulations of cells and thus believe that beside a genetic evaluation, extensive epigenomic screening should become a standard procedure to ensure hiPSCs state before they are used for genome editing and differentiation into neurons of interest. In particular, we suggest that exploitation of the single-cell composition of the epigenome will provide important insights into heterogeneity within hiPSCs subpopulations to fast forward development of reliable hiPSC-based analytical platforms in neurological disorders modelling and before completed hiPSC technology will be implemented in clinical approaches.
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Affiliation(s)
- Maciej Grzybek
- Faculty of Veterinary Medicine, University of Life Sciences in Lublin, Akademicka 12, 20-950 Lublin, Poland; Department of Molecular Biology, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Postępu 36A, 05-552 Magdalenka, Poland.
| | - Aleksandra Golonko
- Department of Biotechnology, Faculty of Civil and Environmental Engineering, Bialystok University of Technology, Wiejska 45E, 15-351 Bialystok, Poland.
| | - Marta Walczak
- Department of Animal Behavior, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Postępu 36A, 05-552 Magdalenka, Poland.
| | - Pawel Lisowski
- Department of Molecular Biology, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, Jastrzębiec, Postępu 36A, 05-552 Magdalenka, Poland; iPS Cell-Based Disease Modelling Group, Max Delbrück Center for Molecular Medicine (MDC) in the Helmholtz Association, Robert-Rössle-Str. 10, 13092 Berlin, Germany.
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Contraction of fully expanded FMR1 alleles to the normal range: predisposing haplotype or rare events? J Hum Genet 2016; 62:269-275. [DOI: 10.1038/jhg.2016.122] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/08/2016] [Accepted: 09/09/2016] [Indexed: 12/28/2022]
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Essebier A, Vera Wolf P, Cao MD, Carroll BJ, Balasubramanian S, Bodén M. Statistical Enrichment of Epigenetic States Around Triplet Repeats that Can Undergo Expansions. Front Neurosci 2016; 10:92. [PMID: 27013954 PMCID: PMC4782033 DOI: 10.3389/fnins.2016.00092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/23/2016] [Indexed: 12/18/2022] Open
Abstract
More than 30 human genetic diseases are linked to tri-nucleotide repeat expansions. There is no known mechanism that explains repeat expansions in full, but changes in the epigenetic state of the associated locus has been implicated in the disease pathology for a growing number of examples. A comprehensive comparative analysis of the genomic features associated with diverse repeat expansions has been lacking. Here, in an effort to decipher the propensity of repeats to undergo expansion and result in a disease state, we determine the genomic coordinates of tri-nucleotide repeat tracts at base pair resolution and computationally establish epigenetic profiles around them. Using three complementary statistical tests, we reveal that several epigenetic states are enriched around repeats that are associated with disease, even in cells that do not harbor expansion, relative to a carefully stratified background. Analysis of over one hundred cell types reveals that epigenetic states generally tend to vary widely between genic regions and cell types. However, there is qualified consistency in the epigenetic signatures of repeats associated with disease suggesting that changes to the chromatin and the DNA around an expanding repeat locus are likely to be similar. These epigenetic signatures may be exploited further to develop models that could explain the propensity of repeats to undergo expansions.
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Affiliation(s)
- Alexandra Essebier
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia, QLD, Australia
| | - Patricia Vera Wolf
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia, QLD, Australia
| | - Minh Duc Cao
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia, QLD, Australia
| | - Bernard J Carroll
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia, QLD, Australia
| | | | - Mikael Bodén
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia, QLD, Australia
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Faruq M, Srivastava AK, Singh S, Gupta R, Dada T, Garg A, Behari M, Mukerji M. Spinocerebellar ataxia 7 (SCA7) in Indian population: predilection of ATXN7-CAG expansion mutation in an ethnic population. Indian J Med Res 2016; 141:187-98. [PMID: 25900954 PMCID: PMC4418155 DOI: 10.4103/0971-5916.155556] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND & OBJECTIVES Spinocerebellar ataxia 7 (SCA7) is a rare form of neurodegenerative disorder with the clinical manifestation of cerebellar ataxia and retinal degeneration. In this study we describe the clinico-genetic characteristics of nine SCA7 families of Indian origin and cross compare these with other available worldwide studies. METHODS Thirty five individuals from nine SCA7 families were clinico-genetically characterized and CAG repeat distribution analysis was carried out in 382 control DNA samples from healthy controls (derived from 21 diverse Indian populations based on ethnic and linguistic and geographical location). RESULTS Of the nine families studied, 22 affected individuals and one asymptomatic carrier were identified. The average age at disease onset was 23.4±12.6 yr. The length of expanded CAG ranged from 40-94 with mean value of 53.2±13.9. The main clinical findings in affecteds individuals included cerebellar ataxia, and retinal degeneration along with hyper-reflexia (95%), slow saccades (85%) and spasticity (45%). Analysis of the association of number of CAG repeats with disease onset revealed that <49 repeats were associated with earlier age at onset in South East Asians compared to European populations. Further analysis of CAG repeats from 21 diverse Indian populations showed pre-mutable repeats (28-34) alleles in the IE-N-LP2 population. Six of the nine families identified in this study belonged to the same ethnic population. INTERPRETATIONS & CONCLUSION Our results show that presenece of SCA7 is relatively rare and confined to one ethnic group from Haryana region of India. We observed a homogeneous phenotypic expression of SCA7 mutation as described earlier and an earlier age of onset in our patients with CAG <49. The identification of pre-mutable allele in IE-N-LP2 suggests this population to be at the risk of SCA7.
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Affiliation(s)
| | - Achal Kumar Srivastava
- Department of Neurology, Neurosciences Centre, All India Institute of Medical Sciences (AIIMS), New Delhi, India
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38
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Bornstein S, Schmidt M, Choonoo G, Levin T, Gray J, Thomas CR, Wong M, McWeeney S. IL-10 and integrin signaling pathways are associated with head and neck cancer progression. BMC Genomics 2016; 17:38. [PMID: 26747525 PMCID: PMC4706689 DOI: 10.1186/s12864-015-2359-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 12/28/2015] [Indexed: 12/12/2022] Open
Abstract
Background Head and neck cancer is morbid with a poor prognosis that has not significantly improved in the past several decades. The purpose of this study was to identify biological pathways underlying progressive head and neck cancer to inform prognostic and adjuvant strategies. We identified 235 head and neck cancer patients in The Cancer Genome Atlas (TCGA) with sufficient clinical annotation regarding therapeutic treatment and disease progression to identify progressors and non-progressors. We compared primary tumor gene expression and mutational status between these two groups. Results 105 genes were differentially expressed between progressors and nonprogressors (FDR < 0.05). Pathway analyses revealed deregulation (FDR < 0.05) of multiple pathways related to integrin signaling as well as IL-10 signaling. A number of genes were uniquely mutated in the progressor cohort including increased frequency of truncating mutations in CTCF (P = 0.007). An 11-gene signature derived from a combination of unique mutations and differential expression was identified (PAGE4, SMTNL1, VTN, CA5A, C1orf43, KRTAP19-1, LEP, HRH4, PAGE5, SEZ6L, CREB3). This signature was associated with decreased overall survival (Logrank Test; P = 0.03443). Cox modeling of both key clinical features and the signature was significant (P = 0.032) with the greatest prognostic improvement seen in the model based on nodal extracapsular spread and alcohol use alone (P = 0.004). Conclusions Molecular analyses of head and neck cancer tumors that progressed despite treatment, identified IL-10 and integrin pathways to be strongly associated with cancer progression. In addition, we identified an 11-gene signature with implications for patient prognostication. Mutational analysis highlighted a potential role for CTCF, a crucial regulator of long-range chromatin interactions, in head and neck cancer progression. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2359-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sophia Bornstein
- Department of Radiation Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Mark Schmidt
- Department of Cell, Developmental & Cancer Biology, Oregon Health & Science University 3, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Gabrielle Choonoo
- OHSU Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Trevor Levin
- Department of Biomedical Engineering, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Joe Gray
- OHSU Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA. .,Department of Biomedical Engineering, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Charles R Thomas
- Department of Radiation Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA. .,OHSU Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Melissa Wong
- Department of Cell, Developmental & Cancer Biology, Oregon Health & Science University 3, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA. .,OHSU Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - Shannon McWeeney
- OHSU Knight Cancer Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA. .,Division of Bioinformatics and Computational Biology, Department of Medical Informatics & Clinical Epidemiology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA. .,Division of Biostatistics, Department of Public Health and Preventive Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
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Gerhardt J. Epigenetic modifications in human fragile X pluripotent stem cells; Implications in fragile X syndrome modeling. Brain Res 2015; 1656:55-62. [PMID: 26475977 DOI: 10.1016/j.brainres.2015.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 08/18/2015] [Accepted: 10/02/2015] [Indexed: 12/18/2022]
Abstract
Patients with fragile X syndrome (FXS) exhibit moderate to severe intellectual disabilities. In addition, one-third of FXS patients show characteristics of autism spectrum disorder. FXS is caused by a trinucleotide repeat expansion, which leads to silencing of the fragile X mental retardation (FMR1) gene. The absence of the FMR1 gene product, FMRP, is the reason for the disease symptoms. It has been suggested that repeat instability and transcription of the FMR1 gene occur during early embryonic development, while after cell differentiation repeats become stable and the FMR1 gene is silent. Epigenetic marks, such as DNA methylation, are associated with gene silencing and repeat stability at the FMR1 locus. However, the mechanisms leading to gene silencing and repeat expansion are still ambiguous, because studies at the human genomic locus were limited until now. The FXS pluripotent stem cells, recently derived from FXS adult cells and FXS blastocysts, are new useful tools to examine these mechanisms at the human endogenous FMR1 locus. This review summarizes the epigenetic features and experimental studies of FXS human embryonic and FXS induced pluripotent stem cells, generated so far. This article is part of a Special Issue entitled SI: Exploiting human neurons.
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Affiliation(s)
- Jeannine Gerhardt
- Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx 10461, USA.
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40
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Fraser J, Williamson I, Bickmore WA, Dostie J. An Overview of Genome Organization and How We Got There: from FISH to Hi-C. Microbiol Mol Biol Rev 2015; 79:347-72. [PMID: 26223848 PMCID: PMC4517094 DOI: 10.1128/mmbr.00006-15] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In humans, nearly two meters of genomic material must be folded to fit inside each micrometer-scale cell nucleus while remaining accessible for gene transcription, DNA replication, and DNA repair. This fact highlights the need for mechanisms governing genome organization during any activity and to maintain the physical organization of chromosomes at all times. Insight into the functions and three-dimensional structures of genomes comes mostly from the application of visual techniques such as fluorescence in situ hybridization (FISH) and molecular approaches including chromosome conformation capture (3C) technologies. Recent developments in both types of approaches now offer the possibility of exploring the folded state of an entire genome and maybe even the identification of how complex molecular machines govern its shape. In this review, we present key methodologies used to study genome organization and discuss what they reveal about chromosome conformation as it relates to transcription regulation across genomic scales in mammals.
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Affiliation(s)
- James Fraser
- Department of Biochemistry, and Goodman Cancer Research Center, McGill University, Montréal, Québec, Canada
| | - Iain Williamson
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Wendy A Bickmore
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Josée Dostie
- Department of Biochemistry, and Goodman Cancer Research Center, McGill University, Montréal, Québec, Canada
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Age-, tissue- and length-dependent bidirectional somatic CAG•CTG repeat instability in an allelic series of R6/2 Huntington disease mice. Neurobiol Dis 2015; 76:98-111. [PMID: 25662336 DOI: 10.1016/j.nbd.2015.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 11/30/2014] [Accepted: 01/25/2015] [Indexed: 12/11/2022] Open
Abstract
The expansion of simple sequence CAG•CTG repeats is associated with a number of inherited disorders including Huntington disease (HD), myotonic dystrophy type 1 and several of the spinocerebellar ataxias. Inherited disease-associated alleles usually exceed 40 repeats and may be in excess of 1,000 repeats in some disorders. Inherited allele length is inversely proportional to age at onset, and frequent germline expansions account for the striking anticipation observed in affected families. Expanded disease associated alleles are also somatically unstable via a pathway that is age dependent and tissue specific, and also appears to be expansion biased. Somatic expansions are thought to contribute toward both tissue specificity and disease progression. Here we have examined the somatic mutational dynamics in brain and peripheral tissues from an allelic series of R6/2 HD transgenic mice inheriting from 52 to >700 CAG repeats. We found age-dependent, tissue-specific somatic instability, with particularly large expansions observed in the striatum and cortex. We also found a positive increase in somatic instability with increasing allele length. Surprisingly, however, the degree of somatic variation did not increase in a linear fashion, but leveled off with increasing allele length. Most unexpectedly, the almost exclusive bias toward the accumulation of expansions observed in mice inheriting smaller alleles was lost, and a high frequency of large somatic contractions was observed in mice inheriting very large alleles (>500 repeats). These data highlight the bidirectional nature of CAG•CTG repeat instability and the subtle balance that exists between expansion and contraction in vivo. Defining the dynamics and tissue specificity of expansion and contraction is important for understanding the role of genetic instability in pathophysiology and in particular the development of novel therapies based on suppressing expansions and/or promoting contractions.
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Usdin K, House NCM, Freudenreich CH. Repeat instability during DNA repair: Insights from model systems. Crit Rev Biochem Mol Biol 2015; 50:142-67. [PMID: 25608779 DOI: 10.3109/10409238.2014.999192] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The expansion of repeated sequences is the cause of over 30 inherited genetic diseases, including Huntington disease, myotonic dystrophy (types 1 and 2), fragile X syndrome, many spinocerebellar ataxias, and some cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat expansions are dynamic, and disease inheritance and progression are influenced by the size and the rate of expansion. Thus, an understanding of the various cellular mechanisms that cooperate to control or promote repeat expansions is of interest to human health. In addition, the study of repeat expansion and contraction mechanisms has provided insight into how repair pathways operate in the context of structure-forming DNA, as well as insights into non-canonical roles for repair proteins. Here we review the mechanisms of repeat instability, with a special emphasis on the knowledge gained from the various model systems that have been developed to study this topic. We cover the repair pathways and proteins that operate to maintain genome stability, or in some cases cause instability, and the cross-talk and interactions between them.
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Affiliation(s)
- Karen Usdin
- Laboratory of Cell and Molecular Biology, NIDDK, NIH , Bethesda, MD , USA
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43
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Russ J, Liu EY, Wu K, Neal D, Suh E, Irwin DJ, McMillan CT, Harms MB, Cairns NJ, Wood EM, Xie SX, Elman L, McCluskey L, Grossman M, Van Deerlin VM, Lee EB. Hypermethylation of repeat expanded C9orf72 is a clinical and molecular disease modifier. Acta Neuropathol 2015; 129:39-52. [PMID: 25388784 DOI: 10.1007/s00401-014-1365-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/04/2014] [Accepted: 11/04/2014] [Indexed: 12/12/2022]
Abstract
C9orf72 promoter hypermethylation inhibits the accumulation of pathologies which have been postulated to be neurotoxic. We tested here whether C9orf72 hypermethylation is associated with prolonged disease in C9orf72 mutation carriers. C9orf72 methylation was quantified from brain or blood using methylation-sensitive restriction enzyme digest-qPCR in a cross-sectional cohort of 118 C9orf72 repeat expansion carriers and 19 non-carrier family members. Multivariate regression models were used to determine whether C9orf72 hypermethylation was associated with age at onset, disease duration, age at death, or hexanucleotide repeat expansion size. Permutation analysis was performed to determine whether C9orf72 methylation is heritable. We observed a high correlation between C9orf72 methylation across tissues including cerebellum, frontal cortex, spinal cord and peripheral blood. While C9orf72 methylation was not significantly different between ALS and FTD and did not predict age at onset, brain and blood C9orf72 hypermethylation was associated with later age at death in FTD (brain: β = 0.18, p = 0.006; blood: β = 0.15, p < 0.001), and blood C9orf72 hypermethylation was associated with longer disease duration in FTD (β = 0.03, p = 0.007). Furthermore, C9orf72 hypermethylation was associated with smaller hexanucleotide repeat length (β = -16.69, p = 0.033). Finally, analysis of pedigrees with multiple mutation carriers demonstrated a significant association between C9orf72 methylation and family relatedness (p < 0.0001). C9orf72 hypermethylation is associated with prolonged disease in C9orf72 repeat expansion carriers with FTD. The attenuated clinical phenotype associated with C9orf72 hypermethylation suggests that slower clinical progression in FTD is associated with reduced expression of mutant C9orf72. These results support the hypothesis that expression of the hexanucleotide repeat expansion is associated with a toxic gain of function.
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44
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Franco MM, Prickett AR, Oakey RJ. The role of CCCTC-binding factor (CTCF) in genomic imprinting, development, and reproduction. Biol Reprod 2014; 91:125. [PMID: 25297545 DOI: 10.1095/biolreprod.114.122945] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
CCCTC-binding factor (CTCF) is the major protein involved in insulator activity in vertebrates, with widespread DNA binding sites in the genome. CTCF participates in many processes related to global chromatin organization and remodeling, contributing to the repression or activation of gene transcription. It is also involved in epigenetic reprogramming and is essential during gametogenesis and embryo development. Abnormal DNA methylation patterns at CTCF motifs may impair CTCF binding to DNA, and are related to fertility disorders in mammals. Therefore, CTCF and its binding sites are important candidate regions to be investigated as molecular markers for gamete and embryo quality. This article reviews the role of CTCF in genomic imprinting, gametogenesis, and early embryo development and, moreover, highlights potential opportunities for environmental influences associated with assisted reproductive techniques (ARTs) to affect CTCF-mediated processes. We discuss the potential use of CTCF as a molecular marker for assessing gamete and embryo quality in the context of improving the efficiency and safety of ARTs.
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Affiliation(s)
- Maurício M Franco
- Embrapa Genetic Resources & Biotechnology, Laboratory of Animal Reproduction, Parque Estação Biológica, Brasília, Brazil
| | - Adam R Prickett
- Department of Medical & Molecular Genetics, King's College London, Guy's Hospital, London, United Kingdom
| | - Rebecca J Oakey
- Department of Medical & Molecular Genetics, King's College London, Guy's Hospital, London, United Kingdom
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45
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Sandi C, Sandi M, Anjomani Virmouni S, Al-Mahdawi S, Pook MA. Epigenetic-based therapies for Friedreich ataxia. Front Genet 2014; 5:165. [PMID: 24917884 PMCID: PMC4042889 DOI: 10.3389/fgene.2014.00165] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/19/2014] [Indexed: 11/29/2022] Open
Abstract
Friedreich ataxia (FRDA) is a lethal autosomal recessive neurodegenerative disorder caused primarily by a homozygous GAA repeat expansion mutation within the first intron of the FXN gene, leading to inhibition of FXN transcription and thus reduced frataxin protein expression. Recent studies have shown that epigenetic marks, comprising chemical modifications of DNA and histones, are associated with FXN gene silencing. Such epigenetic marks can be reversed, making them suitable targets for epigenetic-based therapy. Furthermore, since FRDA is caused by insufficient, but functional, frataxin protein, epigenetic-based transcriptional re-activation of the FXN gene is an attractive therapeutic option. In this review we summarize our current understanding of the epigenetic basis of FXN gene silencing and we discuss current epigenetic-based FRDA therapeutic strategies.
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Affiliation(s)
| | | | | | | | - Mark A. Pook
- Division of Biosciences, School of Health Sciences and Social Care, Brunel University LondonUxbridge, UK
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46
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Dion V. Tissue specificity in DNA repair: lessons from trinucleotide repeat instability. Trends Genet 2014; 30:220-9. [PMID: 24842550 DOI: 10.1016/j.tig.2014.04.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/14/2014] [Accepted: 04/16/2014] [Indexed: 12/13/2022]
Abstract
DNA must constantly be repaired to maintain genome stability. Although it is clear that DNA repair reactions depend on cell type and developmental stage, we know surprisingly little about the mechanisms that underlie this tissue specificity. This is due, in part, to the lack of adequate study systems. This review discusses recent progress toward understanding the mechanism leading to varying rates of instability at expanded trinucleotide repeats (TNRs) in different tissues. Although they are not DNA lesions, TNRs are hotspots for genome instability because normal DNA repair activities cause changes in repeat length. The rates of expansions and contractions are readily detectable and depend on cell identity, making TNR instability a particularly convenient model system. A better understanding of this type of genome instability will provide a foundation for studying tissue-specific DNA repair more generally, which has implications in cancer and other diseases caused by mutations in the caretakers of the genome.
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Affiliation(s)
- Vincent Dion
- University of Lausanne, Center for Integrative Genomics, Bâtiment Génopode, 1015 Lausanne, Switzerland.
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47
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Richard GF, Viterbo D, Khanna V, Mosbach V, Castelain L, Dujon B. Highly specific contractions of a single CAG/CTG trinucleotide repeat by TALEN in yeast. PLoS One 2014; 9:e95611. [PMID: 24748175 PMCID: PMC3991675 DOI: 10.1371/journal.pone.0095611] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 03/28/2014] [Indexed: 12/22/2022] Open
Abstract
Trinucleotide repeat expansions are responsible for more than two dozens severe neurological disorders in humans. A double-strand break between two short CAG/CTG trinucleotide repeats was formerly shown to induce a high frequency of repeat contractions in yeast. Here, using a dedicated TALEN, we show that induction of a double-strand break into a CAG/CTG trinucleotide repeat in heterozygous yeast diploid cells results in gene conversion of the repeat tract with near 100% efficacy, deleting the repeat tract. Induction of the same TALEN in homozygous yeast diploids leads to contractions of both repeats to a final length of 3–13 triplets, with 100% efficacy in cells that survived the double-strand breaks. Whole-genome sequencing of surviving yeast cells shows that the TALEN does not increase mutation rate. No other CAG/CTG repeat of the yeast genome showed any length alteration or mutation. No large genomic rearrangement such as aneuploidy, segmental duplication or translocation was detected. It is the first demonstration that induction of a TALEN in an eukaryotic cell leads to shortening of trinucleotide repeat tracts to lengths below pathological thresholds in humans, with 100% efficacy and very high specificity.
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Affiliation(s)
- Guy-Franck Richard
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, Département Génomes & Génétique, Paris, France
- Sorbonne Universités, UPMC Univ Paris 6, IFD, Paris, France
- CNRS, UMR3525, Paris, France
- * E-mail:
| | - David Viterbo
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, Département Génomes & Génétique, Paris, France
- Sorbonne Universités, UPMC Univ Paris 6, IFD, Paris, France
- CNRS, UMR3525, Paris, France
| | - Varun Khanna
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, Département Génomes & Génétique, Paris, France
- Sorbonne Universités, UPMC Univ Paris 6, IFD, Paris, France
- CNRS, UMR3525, Paris, France
| | - Valentine Mosbach
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, Département Génomes & Génétique, Paris, France
- Sorbonne Universités, UPMC Univ Paris 6, IFD, Paris, France
- CNRS, UMR3525, Paris, France
| | - Lauriane Castelain
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, Département Génomes & Génétique, Paris, France
- Sorbonne Universités, UPMC Univ Paris 6, IFD, Paris, France
- CNRS, UMR3525, Paris, France
| | - Bernard Dujon
- Institut Pasteur, Unité de Génétique Moléculaire des Levures, Département Génomes & Génétique, Paris, France
- Sorbonne Universités, UPMC Univ Paris 6, IFD, Paris, France
- CNRS, UMR3525, Paris, France
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48
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Mohan A, Goodwin M, Swanson MS. RNA-protein interactions in unstable microsatellite diseases. Brain Res 2014; 1584:3-14. [PMID: 24709120 DOI: 10.1016/j.brainres.2014.03.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/25/2014] [Accepted: 03/26/2014] [Indexed: 12/14/2022]
Abstract
A novel RNA-mediated disease mechanism has emerged from studies on dominantly inherited neurological disorders caused by unstable microsatellite expansions in non-coding regions of the genome. These non-coding tandem repeat expansions trigger the production of unusual RNAs that gain a toxic function, which involves the formation of RNA repeat structures that interact with, and alter the activities of, various factors required for normal RNA processing as well as additional cellular functions. In this review, we explore the deleterious effects of toxic RNA expression and discuss the various model systems currently available for studying RNA gain-of-function in neurologic diseases. Common themes, including bidirectional transcription and repeat-associated non-ATG (RAN) translation, have recently emerged from expansion disease studies. These and other discoveries have highlighted the need for further investigations designed to provide the additional mechanistic insights essential for future therapeutic development.
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Affiliation(s)
- Apoorva Mohan
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Cancer Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610-3610, USA
| | - Marianne Goodwin
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Cancer Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610-3610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Cancer Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610-3610, USA.
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Matilla-Dueñas A, Ashizawa T, Brice A, Magri S, McFarland KN, Pandolfo M, Pulst SM, Riess O, Rubinsztein DC, Schmidt J, Schmidt T, Scoles DR, Stevanin G, Taroni F, Underwood BR, Sánchez I. Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias. CEREBELLUM (LONDON, ENGLAND) 2014; 13:269-302. [PMID: 24307138 PMCID: PMC3943639 DOI: 10.1007/s12311-013-0539-y] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.
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Affiliation(s)
- A Matilla-Dueñas
- Health Sciences Research Institute Germans Trias i Pujol (IGTP), Ctra. de Can Ruti, Camí de les Escoles s/n, Badalona, Barcelona, Spain,
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Transcriptionally Repressive Chromatin Remodelling and CpG Methylation in the Presence of Expanded CTG-Repeats at the DM1 Locus. J Nucleic Acids 2013; 2013:567435. [PMID: 24455202 PMCID: PMC3884603 DOI: 10.1155/2013/567435] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 10/22/2013] [Indexed: 12/21/2022] Open
Abstract
An expanded CTG-repeat in the 3′ UTR of the DMPK gene is responsible for myotonic dystrophy type I (DM1). Somatic and intergenerational instability cause the disease to become more severe during life and in subsequent generations. Evidence is accumulating that trinucleotide repeat instability and disease progression involve aberrant chromatin dynamics. We explored the chromatin environment in relation to expanded CTG-repeat tracts in hearts from transgenic mice carrying the DM1 locus with different repeat lengths. Using bisulfite sequencing we detected abundant CpG methylation in the regions flanking the expanded CTG-repeat. CpG methylation was postulated to affect CTCF binding but we found that CTCF binding is not affected by CTG-repeat length in our transgenic mice. We detected significantly decreased DMPK sense and SIX5 transcript expression levels in mice with expanded CTG-repeats. Expression of the DM1 antisense transcript was barely affected by CTG-repeat expansion. In line with altered gene expression, ChIP studies revealed a locally less active chromatin conformation around the expanded CTG-repeat, namely, decreased enrichment of active histone mark H3K9/14Ac and increased H3K9Me3 enrichment (repressive chromatin mark). We also observed binding of PCNA around the repeats, a candidate that could launch chromatin remodelling cascades at expanded repeats, ultimately affecting gene transcription and repeat instability.
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