1
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Kojak N, Kuno J, Fittipaldi KE, Khan A, Wenger D, Glasser M, Donnianni RA, Tang Y, Zhang J, Huling K, Ally R, Mujica AO, Turner T, Magardino G, Huang PY, Kerk SY, Droguett G, Prissette M, Rojas J, Gomez T, Gagliardi A, Hunt C, Rabinowitz JS, Gong G, Poueymirou W, Chiao E, Zambrowicz B, Siao CJ, Kajimura D. Somatic and intergenerational G4C2 hexanucleotide repeat instability in a human C9orf72 knock-in mouse model. Nucleic Acids Res 2024; 52:5732-5755. [PMID: 38597682 PMCID: PMC11162798 DOI: 10.1093/nar/gkae250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 03/19/2024] [Accepted: 03/28/2024] [Indexed: 04/11/2024] Open
Abstract
Expansion of a G4C2 repeat in the C9orf72 gene is associated with familial Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Dementia (FTD). To investigate the underlying mechanisms of repeat instability, which occurs both somatically and intergenerationally, we created a novel mouse model of familial ALS/FTD that harbors 96 copies of G4C2 repeats at a humanized C9orf72 locus. In mouse embryonic stem cells, we observed two modes of repeat expansion. First, we noted minor increases in repeat length per expansion event, which was dependent on a mismatch repair pathway protein Msh2. Second, we found major increases in repeat length per event when a DNA double- or single-strand break (DSB/SSB) was artificially introduced proximal to the repeats, and which was dependent on the homology-directed repair (HDR) pathway. In mice, the first mode primarily drove somatic repeat expansion. Major changes in repeat length, including expansion, were observed when SSB was introduced in one-cell embryos, or intergenerationally without DSB/SSB introduction if G4C2 repeats exceeded 400 copies, although spontaneous HDR-mediated expansion has yet to be identified. These findings provide a novel strategy to model repeat expansion in a non-human genome and offer insights into the mechanism behind C9orf72 G4C2 repeat instability.
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Affiliation(s)
- Nada Kojak
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Junko Kuno
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | - David Wenger
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | - Yajun Tang
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Jade Zhang
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Katie Huling
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Roxanne Ally
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | | | - Pei Yi Huang
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | - Sze Yen Kerk
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | - Jose Rojas
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | | | | | | | - Guochun Gong
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
| | | | - Eric Chiao
- Regeneron Pharmaceuticals, Tarrytown, NY 10591, USA
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2
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Wimberger S, Akrap N, Firth M, Brengdahl J, Engberg S, Schwinn MK, Slater MR, Lundin A, Hsieh PP, Li S, Cerboni S, Sumner J, Bestas B, Schiffthaler B, Magnusson B, Di Castro S, Iyer P, Bohlooly-Y M, Machleidt T, Rees S, Engkvist O, Norris T, Cadogan EB, Forment JV, Šviković S, Akcakaya P, Taheri-Ghahfarokhi A, Maresca M. Simultaneous inhibition of DNA-PK and Polϴ improves integration efficiency and precision of genome editing. Nat Commun 2023; 14:4761. [PMID: 37580318 PMCID: PMC10425386 DOI: 10.1038/s41467-023-40344-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/25/2023] [Indexed: 08/16/2023] Open
Abstract
Genome editing, specifically CRISPR/Cas9 technology, has revolutionized biomedical research and offers potential cures for genetic diseases. Despite rapid progress, low efficiency of targeted DNA integration and generation of unintended mutations represent major limitations for genome editing applications caused by the interplay with DNA double-strand break repair pathways. To address this, we conduct a large-scale compound library screen to identify targets for enhancing targeted genome insertions. Our study reveals DNA-dependent protein kinase (DNA-PK) as the most effective target to improve CRISPR/Cas9-mediated insertions, confirming previous findings. We extensively characterize AZD7648, a selective DNA-PK inhibitor, and find it to significantly enhance precise gene editing. We further improve integration efficiency and precision by inhibiting DNA polymerase theta (Polϴ). The combined treatment, named 2iHDR, boosts templated insertions to 80% efficiency with minimal unintended insertions and deletions. Notably, 2iHDR also reduces off-target effects of Cas9, greatly enhancing the fidelity and performance of CRISPR/Cas9 gene editing.
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Affiliation(s)
- Sandra Wimberger
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden.
- Department of Chemistry & Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
| | - Nina Akrap
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Mike Firth
- Data Sciences & Quantitative Biology, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Johan Brengdahl
- Cell Assay Development, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Susanna Engberg
- Cell Engineering Sweden, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | | | | | - Anders Lundin
- Translational Genomics, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Pei-Pei Hsieh
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Songyuan Li
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Silvia Cerboni
- Translational Science & Experimental Medicine, Research and Early Development, Respiratory & Immunology (R&I), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Jonathan Sumner
- Cell Immunology, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Burcu Bestas
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Bastian Schiffthaler
- Data Sciences & Quantitative Biology, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Björn Magnusson
- Translational Genomics, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Silvio Di Castro
- Compound Synthesis & Management, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Preeti Iyer
- Molecular AI, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Mohammad Bohlooly-Y
- Translational Genomics, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | | | - Steve Rees
- Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Ola Engkvist
- Molecular AI, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Tyrell Norris
- Cell Engineering Sweden, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | | | | | - Saša Šviković
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Pinar Akcakaya
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Amir Taheri-Ghahfarokhi
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Marcello Maresca
- Genome Engineering, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden.
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3
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Engineered helicase replaces thermocycler in DNA amplification while retaining desired PCR characteristics. Nat Commun 2022; 13:6312. [PMID: 36274095 PMCID: PMC9588791 DOI: 10.1038/s41467-022-34076-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 10/12/2022] [Indexed: 12/25/2022] Open
Abstract
Polymerase Chain Reaction (PCR) is an essential method in molecular diagnostics and life sciences. PCR requires thermal cycling for heating the DNA for strand separation and cooling it for replication. The process uses a specialized hardware and exposes biomolecules to temperatures above 95 °C. Here, we engineer a PcrA M6 helicase with enhanced speed and processivity to replace the heating step by enzymatic DNA unwinding while retaining desired PCR characteristics. We name this isothermal amplification method SHARP (SSB-Helicase Assisted Rapid PCR) because it uses the engineered helicase and single-stranded DNA binding protein (SSB) in addition to standard PCR reagents. SHARP can generate amplicons with lengths of up to 6000 base pairs. SHARP can produce functional DNA, a plasmid that imparts cells with antibiotic resistance, and can amplify specific fragments from genomic DNA of human cells. We further use SHARP to assess the outcome of CRISPR-Cas9 editing at endogenous genomic sites.
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4
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Sargsyan A, Hovhannisyan G, Simonyan A, Arakelyan M, Arzumanyan M, Aroutiounian R. Application of land snail Helix lucorum for evaluation of genotoxicity of soil pollution. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 878:503500. [PMID: 35649673 DOI: 10.1016/j.mrgentox.2022.503500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 04/15/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
Application of native species as sentinels allows environmental scientists to determine real genotoxic impact of environmental pollutants. The present study aims at investigating the DNA damage in the land snail Helix lucorum as a biomarker of soil pollution. For this reason, the genotoxic impact of contaminated soil on H. lucorum, collected from different polluted areas, was investigated using the comet assay in haemocytes and digestive gland cells. An increase in DNA damage was found in the snails sampled from polluted sites compared with the reference one. Strong correlations between DNA damage in haemocytes and digestive gland cells with the level of contamination indicate pollution-induced genotoxic effects in both tissues. At the same time, the digestive gland was more sensitive towards pollutants compared with haemolymph. A direct relationship between concentrations of Cu, As and Mo in soil and the number of damaged cells for hаemolymph and digestive gland tissue was found. However, the data obtained reflect the total genotoxicity of all pollutants in the studied areas. Significant correlations between the DNA damage measured by the comet assay and metal contents in soil indicate that it is a suitable biomarker in ecotoxicological studies. Our results indicate the effectiveness of H. lucorum in biomonitoring of environmental pollution.
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Affiliation(s)
- Anzhela Sargsyan
- Department of Genetics and Cytology, Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia.
| | - Galina Hovhannisyan
- Department of Genetics and Cytology, Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia; Laboratory of General and Molecular Genetics, RI "Biology", Faculty of Biology Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia.
| | - Anna Simonyan
- A.V. Dumansky Institute of Colloid Chemistry and Water Chemistry of the National Academy of Sciences of Ukraine, 42 Vernadsky Avenue, P.O. Box 03142, Kyiv, Ukraine.
| | - Marine Arakelyan
- Department of Zoology, Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia.
| | - Meri Arzumanyan
- Department of Zoology, Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia.
| | - Rouben Aroutiounian
- Department of Genetics and Cytology, Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia; Laboratory of General and Molecular Genetics, RI "Biology", Faculty of Biology Yerevan State University, 8 Charents Str., P.O. Box 0025, Yerevan, Armenia.
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5
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Fukunaga H, Yokoya A, Prise KM. A Brief Overview of Radiation-Induced Effects on Spermatogenesis and Oncofertility. Cancers (Basel) 2022; 14:cancers14030805. [PMID: 35159072 PMCID: PMC8834293 DOI: 10.3390/cancers14030805] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/03/2022] [Accepted: 02/03/2022] [Indexed: 02/06/2023] Open
Abstract
Simple Summary Spermatogenesis is one of the most important processes for the propagation of life; however, the testes’ ability to form sperm via this differentiation process is highly radiosensitive and easily impacted by exposure to environmental, occupational, or therapeutic radiation. Furthermore, the possibility that radiation effects on the gonads can be passed on from generation to generation should not be overlooked. This review focuses on the radiation-induced effects on spermatogenesis and the transgenerational effects. We also explore the potential of novel radiobiological approaches to improve male fertility preservation during radiotherapy. Abstract The genotoxicity of radiation on germ cells may be passed on to the next generation, thus its elucidation is not only a scientific issue but also an ethical, legal, and social issue in modern society. In this article, we briefly overview the effects of radiation on spermatogenesis and its associated genotoxicity, including the latest findings in the field of radiobiology. The potential role of transgenerational effects is still poorly understood, and further research in this area is desirable. Furthermore, from the perspective of oncofertility, we discuss the historical background and clinical importance of preserving male fertility during radiation treatment and the potential of microbeam radiotherapy. We hope that this review will contribute to stimulating further discussions and investigations for therapies for pediatric and adolescent/young adult patients.
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Affiliation(s)
- Hisanori Fukunaga
- Center for Environmental and Health Sciences, Hokkaido University, Sapporo 060-0812, Japan
- Correspondence:
| | - Akinari Yokoya
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Ibaraki 319-1106, Japan;
- Graduate School of Science and Engineering, Ibaraki University, Ibaraki 310-8512, Japan
| | - Kevin M. Prise
- Patrick G Johnstone Centre for Cancer Research, Queen’s University Belfast, Belfast BT9 7AE, UK;
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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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Ciminera AK, Shuck SC, Termini J. Elevated glucose increases genomic instability by inhibiting nucleotide excision repair. Life Sci Alliance 2021; 4:4/10/e202101159. [PMID: 34426491 PMCID: PMC8385305 DOI: 10.26508/lsa.202101159] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 12/23/2022] Open
Abstract
Exposure to chronic, elevated glucose inhibits nucleotide excision repair, which leads to accumulation of DNA glycation adducts, increased DNA strand breaks, and activation of the DNA damage response. We investigated potential mechanisms by which elevated glucose may promote genomic instability. Gene expression studies, protein measurements, mass spectroscopic analyses, and functional assays revealed that elevated glucose inhibited the nucleotide excision repair (NER) pathway, promoted DNA strand breaks, and increased levels of the DNA glycation adduct N2-(1-carboxyethyl)-2ʹ-deoxyguanosine (CEdG). Glycation stress in NER-competent cells yielded single-strand breaks accompanied by ATR activation, γH2AX induction, and enhanced non-homologous end-joining and homology-directed repair. In NER-deficient cells, glycation stress activated ATM/ATR/H2AX, consistent with double-strand break formation. Elevated glucose inhibited DNA repair by attenuating hypoxia-inducible factor-1α–mediated transcription of NER genes via enhanced 2-ketoglutarate–dependent prolyl hydroxylase (PHD) activity. PHD inhibition enhanced transcription of NER genes and facilitated CEdG repair. These results are consistent with a role for hyperglycemia in promoting genomic instability as a potential mechanism for increasing cancer risk in metabolic disease. Because of the pleiotropic functions of many NER genes beyond DNA repair, these results may have broader implications for cellular pathophysiology.
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Affiliation(s)
- Alexandra K Ciminera
- Department of Molecular Medicine, Beckman Research Institute at City of Hope, Duarte, CA, USA.,Irell and Manella Graduate School of Biomedical Sciences, City of Hope, Duarte, CA, USA
| | - Sarah C Shuck
- Department of Molecular Medicine, Beckman Research Institute at City of Hope, Duarte, CA, USA
| | - John Termini
- Department of Molecular Medicine, Beckman Research Institute at City of Hope, Duarte, CA, USA
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8
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Lou MM, Tang XQ, Wang GM, He J, Luo F, Guan MF, Wang F, Zou H, Wang JY, Zhang Q, Xu MJ, Shi QL, Shen LB, Ma GM, Wu Y, Zhang YY, Liang AB, Wang TH, Xiong LL, Wang J, Xu J, Wang WY. Long noncoding RNA BS-DRL1 modulates the DNA damage response and genome stability by interacting with HMGB1 in neurons. Nat Commun 2021; 12:4075. [PMID: 34210972 PMCID: PMC8249382 DOI: 10.1038/s41467-021-24236-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 06/09/2021] [Indexed: 12/15/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) are known to regulate DNA damage response (DDR) and genome stability in proliferative cells. However, it remains unknown whether lncRNAs are involved in these vital biological processes in post-mitotic neurons. Here, we report and characterize a lncRNA, termed Brain Specific DNA-damage Related lncRNA1 (BS-DRL1), in the central nervous system. BS-DRL1 is a brain-specific lncRNA and depletion of BS-DRL1 in neurons leads to impaired DDR upon etoposide treatment in vitro. Mechanistically, BS-DRL1 interacts with HMGB1, a chromatin protein that is important for genome stability, and is essential for the assembly of HMGB1 on chromatin. BS-DRL1 mediated DDR exhibits cell-type specificity in the cortex and cerebellum in gamma-irradiated mice and BS-DRL1 knockout mice show impaired motor function and concomitant purkinje cell degeneration. Our study extends the understanding of lncRNAs in DDR and genome stability and implies a protective role of lncRNA against neurodegeneration.
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Affiliation(s)
- Min-Min Lou
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiao-Qiang Tang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Guang-Ming Wang
- East Hospital, Tongji University School of Medicine, Shanghai, China
- Department of Hematology, Tongji Hospital of Tongji University School of Medicine, Shanghai, China
- Postdoctoral Station of Clinical Medicine, Shanghai Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jia He
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fang Luo
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
| | - Ming-Feng Guan
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fei Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Huan Zou
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jun-Ying Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qun Zhang
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Ming-Jian Xu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
| | - Qi-Li Shi
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
| | - Li-Bing Shen
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
| | - Guo-Ming Ma
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yi Wu
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yao-Yang Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China
| | - Ai-Bin Liang
- Postdoctoral Station of Clinical Medicine, Shanghai Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Ting-Hua Wang
- Animal Center of Zoology, Institute of Neuroscience, Kunming medical University, Kunming, China
| | - Liu-Lin Xiong
- Animal Center of Zoology, Institute of Neuroscience, Kunming medical University, Kunming, China
| | - Jian Wang
- Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Jing'an District, Shanghai, China.
| | - Jun Xu
- East Hospital, Tongji University School of Medicine, Shanghai, China.
| | - Wen-Yuan Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese academy of Science, Shanghai, 200032, China.
- Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China.
- Animal Center of Zoology, Institute of Neuroscience, Kunming medical University, Kunming, China.
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9
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The sustained expression of Cas9 targeting toxic RNAs reverses disease phenotypes in mouse models of myotonic dystrophy type 1. Nat Biomed Eng 2020; 5:157-168. [PMID: 32929188 DOI: 10.1038/s41551-020-00607-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/10/2020] [Indexed: 12/19/2022]
Abstract
Myotonic dystrophy type I (DM1) is a multisystemic autosomal-dominant inherited human disorder that is caused by CTG microsatellite repeat expansions (MREs) in the 3' untranslated region of DMPK. Toxic RNAs expressed from such repetitive sequences can be eliminated using CRISPR-mediated RNA targeting, yet evidence of its in vivo efficacy and durability is lacking. Here, using adult and neonatal mouse models of DM1, we show that intramuscular or systemic injections of adeno-associated virus (AAV) vectors encoding nuclease-dead Cas9 and a single-guide RNA targeting CUG repeats results in the expression of the RNA-targeting Cas9 for up to three months, redistribution of the RNA-splicing protein muscleblind-like splicing regulator 1, elimination of foci of toxic RNA, reversal of splicing biomarkers and amelioration of myotonia. The sustained reversal of DM1 phenotypes provides further support that RNA-targeting Cas9 is a viable strategy for treating DM1 and other MRE-associated diseases.
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10
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FOXL2 directs DNA double-strand break repair pathways by differentially interacting with Ku. Nat Commun 2020; 11:2010. [PMID: 32332759 PMCID: PMC7181608 DOI: 10.1038/s41467-020-15748-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 03/22/2020] [Indexed: 12/26/2022] Open
Abstract
The balance between major DNA double-strand break (DSB) repair pathways is influenced by binding of the Ku complex, a XRCC5/6 heterodimer, to DSB ends, initiating non-homologous end joining (NHEJ) but preventing additional DSB end resection and homologous recombination (HR). However, the key molecular cue for Ku recruitment to DSB sites is unknown. Here, we report that FOXL2, a forkhead family transcriptional factor, directs DSB repair pathway choice by acetylation-dependent binding to Ku. Upon DSB induction, SIRT1 translocates to the nucleus and deacetylates FOXL2 at lysine 124, leading to liberation of XRCC5 and XRCC6 from FOXL2 and formation of the Ku complex. FOXL2 ablation enhances Ku recruitment to DSB sites, imbalances DSB repair kinetics by accelerating NHEJ and inhibiting HR, and thus leads to catastrophic genomic events. Our study unveils the SIRT1-(de)acetylated FOXL2-Ku axis that governs the balance of DSB repair pathways to maintain genome integrity.
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11
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Hu M, Lou Y, Liu S, Mao Y, Le F, Wang L, Li L, Wang Q, Li H, Lou H, Wang N, Jin F. Altered expression of DNA damage repair genes in the brain tissue of mice conceived by in vitro fertilization. Mol Hum Reprod 2020; 26:141-153. [PMID: 32003796 DOI: 10.1093/molehr/gaaa010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 12/16/2019] [Accepted: 01/08/2020] [Indexed: 12/22/2022] Open
Abstract
Our previous study revealed a higher incidence of gene dynamic mutation in newborns conceived by IVF, highlighting that IVF may be disruptive to the DNA stability of IVF offspring. However, the underlying mechanisms remain unclear. The DNA damage repair system plays an essential role in gene dynamic mutation and neurodegenerative disease. To evaluate the long-term impact of IVF on DNA damage repair genes, we established an IVF mouse model and analyzed gene and protein expression levels of MSH2, MSH3, MSH6, MLH1, PMS2, OGG1, APEX1, XPA and RPA1 and also the amount of H2AX phosphorylation of serine 139 which is highly suggestive of DNA double-strand break (γH2AX expression level) in the brain tissue of IVF conceived mice and their DNA methylation status using quantitative real-time PCR, western blotting and pyrosequencing. Furthermore, we assessed the capacity of two specific non-physiological factors in IVF procedures during preimplantation development. The results demonstrated that the expression and methylation levels of some DNA damage repair genes in the brain tissue of IVF mice were significantly changed at 3 weeks, 10 weeks and 1.5 years of age, when compared with the in vivo control group. In support of mouse model findings, oxygen concentration of in vitro culture environment was shown to have the capacity to modulate gene expression and DNA methylation levels of some DNA damage repair genes. In summary, our study indicated that IVF could bring about long-term alterations of gene and protein expression and DNA methylation levels of some DNA damage repair genes in the brain tissue and these alterations might be resulted from the different oxygen concentration of culture environment, providing valuable perspectives to improve the safety and efficiency of IVF at early embryonic stage and also throughout different life stages.
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Affiliation(s)
- Minhao Hu
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Yiyun Lou
- Department of Gynaecology, Hangzhou Hospital of Traditional Chinese Medicine, Hangzhou 310007, China
| | - Shuyuan Liu
- Department of Gynaecology, Weifang Maternal and Child Health Hospital, Weifang 261000, China
| | - Yuchan Mao
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Fang Le
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Liya Wang
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Lejun Li
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Qijing Wang
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Hongping Li
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Hangying Lou
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Ning Wang
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China
| | - Fan Jin
- Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University School of Medicine, 1 Xueshi Road, Hangzhou 310006, China.,Women's Reproductive Health Laboratory of Zhejiang Province, Key Laboratory of Reproductive Genetics, Ministry of Education, Hangzhou 310006, China
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12
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Tomé S, Gourdon G. DM1 Phenotype Variability and Triplet Repeat Instability: Challenges in the Development of New Therapies. Int J Mol Sci 2020; 21:ijms21020457. [PMID: 31936870 PMCID: PMC7014087 DOI: 10.3390/ijms21020457] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 01/02/2020] [Accepted: 01/08/2020] [Indexed: 02/07/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a complex neuromuscular disease caused by an unstable cytosine thymine guanine (CTG) repeat expansion in the DMPK gene. This disease is characterized by high clinical and genetic variability, leading to some difficulties in the diagnosis and prognosis of DM1. Better understanding the origin of this variability is important for developing new challenging therapies and, in particular, for progressing on the path of personalized treatments. Here, we reviewed CTG triplet repeat instability and its modifiers as an important source of phenotypic variability in patients with DM1.
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13
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Cinesi C, Yang B, Dion V. GFP Reporters to Monitor Instability and Expression of Expanded CAG/CTG Repeats. Methods Mol Biol 2020; 2056:255-268. [PMID: 31586353 DOI: 10.1007/978-1-4939-9784-8_16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Expanded CAG/CTG repeats are genetically unstable and, upon expression, cause neurological and neuromuscular diseases. The molecular mechanisms of repeat instability and expression remain poorly understood despite their importance for the pathogenesis of a family of 14 devastating human diseases. This is in part because conventional assays are tedious and time-consuming. Recently, however, GFP-based reporters have been designed to provide a rapid and reliable means of assessing these parameters. Here we provide protocols for quantifying repeat instability and expression using a GFP-based chromosomal reporter and the newly developed ParB/ANCHOR-mediated Inducible Targeting (PInT) and how to validate the results.
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Affiliation(s)
- Cinzia Cinesi
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Bin Yang
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Vincent Dion
- Dementia Research Institute, Cardiff University, Cardiff, UK.
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14
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Fukunaga H, Yokoya A, Taki Y, Butterworth KT, Prise KM. Precision Radiotherapy and Radiation Risk Assessment: How Do We Overcome Radiogenomic Diversity? TOHOKU J EXP MED 2019; 247:223-235. [PMID: 30971620 DOI: 10.1620/tjem.247.223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Precision medicine is a rapidly developing area that aims to deliver targeted therapies based on individual patient characteristics. However, current radiation treatment is not yet personalized; consequently, there is a critical need for specific patient characteristics of both tumor and normal tissues to be fully incorporated into dose prescription. Furthermore, current risk assessment following environmental, occupational, or accidental exposures to radiation is based on population effects, and does not account for individual diversity underpinning radiosensitivity. The lack of personalized approaches in both radiotherapy and radiation risk assessment resulted in the current situation where a population-based model, effective dose, is being used. In this review article, to stimulate scientific discussion for precision medicine in both radiotherapy and radiation risk assessment, we propose a novel radiological concept and metric - the personalized dose and the personalized risk index - that incorporate individual physiological, lifestyle-related and genomic variations and radiosensitivity, outlining the potential clinical application for precision medicine. We also review on recent progress in both genomics and biobanking research, which is promising for providing novel insights into individual radiosensitivity, and for creating a novel conceptual framework of precision radiotherapy and radiation risk assessment.
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Affiliation(s)
- Hisanori Fukunaga
- Centre for Cancer Research and Cell Biology, Queen's University Belfast
| | - Akinari Yokoya
- Tokai Quantum Beam Science Center, National Institutes for Quantum and Radiological Science and Technology
| | - Yasuyuki Taki
- Institute of Development, Aging and Cancer, Tohoku University
| | | | - Kevin M Prise
- Centre for Cancer Research and Cell Biology, Queen's University Belfast
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15
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Malbec R, Chami B, Aeschbach L, Ruiz Buendía GA, Socol M, Joseph P, Leïchlé T, Trofimenko E, Bancaud A, Dion V. µLAS: Sizing of expanded trinucleotide repeats with femtomolar sensitivity in less than 5 minutes. Sci Rep 2019; 9:23. [PMID: 30631115 PMCID: PMC6328573 DOI: 10.1038/s41598-018-36632-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 11/23/2018] [Indexed: 11/09/2022] Open
Abstract
We present µLAS, a lab-on-chip system that concentrates, separates, and detects DNA fragments in a single module. µLAS speeds up DNA size analysis in minutes using femtomolar amounts of amplified DNA. Here we tested the relevance of µLAS for sizing expanded trinucleotide repeats, which cause over 20 different neurological and neuromuscular disorders. Because the length of trinucleotide repeats correlates with the severity of the diseases, it is crucial to be able to size repeat tract length accurately and efficiently. Expanded trinucleotide repeats are however genetically unstable and difficult to amplify. Thus, the amount of amplified material to work with is often limited, making its analysis labor-intensive. We report the detection of heterogeneous allele lengths in 8 samples from myotonic dystrophy type 1 and Huntington disease patients with up to 750 CAG/CTG repeats in five minutes or less. The high sensitivity of the method allowed us to minimize the number of amplification cycles and thus reduce amplification artefacts without compromising the detection of the expanded allele. These results suggest that µLAS can speed up routine molecular biology applications of repetitive sequences and may improve the molecular diagnostic of expanded repeat disorders.
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Affiliation(s)
- Rémi Malbec
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, 31031, France
| | - Bayan Chami
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, 31031, France
| | - Lorène Aeschbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Bâtiment Génopode, Lausanne, 1015, Switzerland
| | - Gustavo A Ruiz Buendía
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Bâtiment Génopode, Lausanne, 1015, Switzerland
| | - Marius Socol
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, 31031, France
| | - Pierre Joseph
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, 31031, France
| | - Thierry Leïchlé
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, 31031, France
| | - Evgeniya Trofimenko
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Bâtiment Génopode, Lausanne, 1015, Switzerland
- Department of Physiology, University of Lausanne, Rue du Bugnon 7, Lausanne, 1005, Switzerland
| | - Aurélien Bancaud
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, 31031, France.
| | - Vincent Dion
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Bâtiment Génopode, Lausanne, 1015, Switzerland.
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16
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Wiesweg M, Kasper S, Worm K, Herold T, Reis H, Sara L, Metzenmacher M, Abendroth A, Darwiche K, Aigner C, Wedemeyer HH, Helfritz FA, Stuschke M, Schumacher B, Markus P, Paul A, Rahmann S, Schmid KW, Schuler M. Impact of RAS mutation subtype on clinical outcome—a cross-entity comparison of patients with advanced non-small cell lung cancer and colorectal cancer. Oncogene 2018; 38:2953-2966. [DOI: 10.1038/s41388-018-0634-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/21/2018] [Accepted: 11/21/2018] [Indexed: 12/21/2022]
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17
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Mollica PA, Zamponi M, Reid JA, Sharma DK, White AE, Ogle RC, Bruno RD, Sachs PC. Epigenetic alterations mediate iPSC-induced normalization of DNA repair gene expression and TNR stability in Huntington's disease cells. J Cell Sci 2018; 131:jcs.215343. [PMID: 29898922 DOI: 10.1242/jcs.215343] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 06/05/2018] [Indexed: 12/22/2022] Open
Abstract
Huntington's disease (HD) is a rare autosomal dominant neurodegenerative disorder caused by a cytosine-adenine-guanine (CAG) trinucleotide repeat (TNR) expansion within the HTT gene. The mechanisms underlying HD-associated cellular dysfunction in pluripotency and neurodevelopment are poorly understood. We had previously identified downregulation of selected DNA repair genes in HD fibroblasts relative to wild-type fibroblasts, as a result of promoter hypermethylation. Here, we tested the hypothesis that hypomethylation during cellular reprogramming to the induced pluripotent stem cell (iPSC) state leads to upregulation of DNA repair genes and stabilization of TNRs in HD cells. We sought to determine how the HD TNR region is affected by global epigenetic changes through cellular reprogramming and early neurodifferentiation. We find that early stage HD-affected neural stem cells (HD-NSCs) contain increased levels of global 5-hydroxymethylation (5-hmC) and normalized DNA repair gene expression. We confirm TNR stability is induced in iPSCs, and maintained in HD-NSCs. We also identify that upregulation of 5-hmC increases ten-eleven translocation 1 and 2 (TET1/2) protein levels, and show their knockdown leads to a corresponding decrease in the expression of select DNA repair genes. We further confirm decreased expression of TET1/2-regulating miR-29 family members in HD-NSCs. Our findings demonstrate that mechanisms associated with pluripotency induction lead to a recovery in the expression of select DNA repair gene and stabilize pathogenic TNRs in HD.
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Affiliation(s)
- Peter A Mollica
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA.,Molecular Diagnostics Laboratory, Sentara Norfolk General Hospital, Norfolk, VA 23507, USA
| | - Martina Zamponi
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA.,Biomedical Engineering Institute, Old Dominion University, Norfolk, VA 23529, USA
| | - John A Reid
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA.,Biomedical Engineering Institute, Old Dominion University, Norfolk, VA 23529, USA
| | - Deepak K Sharma
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Alyson E White
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Roy C Ogle
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Robert D Bruno
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Patrick C Sachs
- Department of Medical Diagnostic and Translational Sciences, Old Dominion University, Norfolk, VA 23529, USA
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18
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McGinty RJ, Mirkin SM. Cis- and Trans-Modifiers of Repeat Expansions: Blending Model Systems with Human Genetics. Trends Genet 2018; 34:448-465. [PMID: 29567336 PMCID: PMC5959756 DOI: 10.1016/j.tig.2018.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 12/30/2022]
Abstract
Over 30 hereditary diseases are caused by the expansion of microsatellite repeats. The length of the expandable repeat is the main hereditary determinant of these disorders. They are also affected by numerous genomic variants that are either nearby (cis) or physically separated from (trans) the repetitive locus, which we review here. These genetic variants have largely been elucidated in model systems using gene knockouts, while a few have been directly observed as single-nucleotide polymorphisms (SNPs) in patients. There is a notable disconnect between these two bodies of knowledge: knockouts poorly approximate the SNP-level variation in human populations that gives rise to medically relevant cis- and trans-modifiers, while the rarity of these diseases limits the statistical power of SNP-based analysis in humans. We propose that high-throughput SNP-based screening in model systems could become a useful approach to quickly identify and characterize modifiers of clinical relevance for patients.
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Affiliation(s)
- Ryan J McGinty
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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19
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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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20
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Minimizing carry-over PCR contamination in expanded CAG/CTG repeat instability applications. Sci Rep 2017; 7:18026. [PMID: 29269788 PMCID: PMC5740160 DOI: 10.1038/s41598-017-18168-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 12/06/2017] [Indexed: 11/08/2022] Open
Abstract
Expanded CAG/CTG repeats underlie the aetiology of 14 neurological and neuromuscular disorders. The size of the repeat tract determines in large part the severity of these disorders with longer tracts causing more severe phenotypes. Expanded CAG/CTG repeats are also unstable in somatic tissues, which is thought to modify disease progression. Routine molecular biology applications involving these repeats, including quantifying their instability, are plagued by low PCR yields. This leads to the need for setting up more PCRs of the same locus, thereby increasing the risk of carry-over contamination. Here we aimed to reduce this risk by pre-treating the samples with a Uracil N-Glycosylase (Ung) and using dUTP instead of dTTP in PCRs. We successfully applied this method to the PCR amplification of expanded CAG/CTG repeats, their sequencing, and their molecular cloning. In addition, we optimized the gold-standard method for measuring repeat instability, small-pool PCR (SP-PCR), such that it can be used together with Ung and dUTP-containing PCRs, without compromising data quality. We performed SP-PCR on myotonic-dystrophy-derived samples containing an expansion as large as 1000 repeats, demonstrating the applicability to clinically-relevant material. Thus, we expect the protocols herein to be applicable for molecular diagnostics of expanded repeat disorders.
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21
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Chatterjee N, Walker GC. Mechanisms of DNA damage, repair, and mutagenesis. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2017; 58:235-263. [PMID: 28485537 PMCID: PMC5474181 DOI: 10.1002/em.22087] [Citation(s) in RCA: 987] [Impact Index Per Article: 141.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 03/16/2017] [Indexed: 05/08/2023]
Abstract
Living organisms are continuously exposed to a myriad of DNA damaging agents that can impact health and modulate disease-states. However, robust DNA repair and damage-bypass mechanisms faithfully protect the DNA by either removing or tolerating the damage to ensure an overall survival. Deviations in this fine-tuning are known to destabilize cellular metabolic homeostasis, as exemplified in diverse cancers where disruption or deregulation of DNA repair pathways results in genome instability. Because routinely used biological, physical and chemical agents impact human health, testing their genotoxicity and regulating their use have become important. In this introductory review, we will delineate mechanisms of DNA damage and the counteracting repair/tolerance pathways to provide insights into the molecular basis of genotoxicity in cells that lays the foundation for subsequent articles in this issue. Environ. Mol. Mutagen. 58:235-263, 2017. © 2017 Wiley Periodicals, Inc.
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22
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Ren Y, Lai Y, Laverde EE, Lei R, Rein HL, Liu Y. Modulation of trinucleotide repeat instability by DNA polymerase β polymorphic variant R137Q. PLoS One 2017; 12:e0177299. [PMID: 28475635 PMCID: PMC5419657 DOI: 10.1371/journal.pone.0177299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/25/2017] [Indexed: 12/13/2022] Open
Abstract
Trinucleotide repeat (TNR) instability is associated with human neurodegenerative diseases and cancer. Recent studies have pointed out that DNA base excision repair (BER) mediated by DNA polymerase β (pol β) plays a crucial role in governing somatic TNR instability in a damage-location dependent manner. It has been shown that the activities and function of BER enzymes and cofactors can be modulated by their polymorphic variations. This could alter the function of BER in regulating TNR instability. However, the roles of BER polymorphism in modulating TNR instability remain to be elucidated. A previous study has shown that a pol β polymorphic variant, polβR137Q is associated with cancer due to its impaired polymerase activity and its deficiency in interacting with a BER cofactor, proliferating cell nuclear antigen (PCNA). In this study, we have studied the effect of the pol βR137Q variant on TNR instability. We showed that pol βR137Q exhibited weak DNA synthesis activity to cause TNR deletion during BER. We demonstrated that similar to wild-type pol β, the weak DNA synthesis activity of pol βR137Q allowed it to skip over a small loop formed on the template strand, thereby facilitating TNR deletion during BER. Our results further suggest that carriers with pol βR137Q polymorphic variant may not exhibit an elevated risk of developing human diseases that are associated with TNR instability.
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Affiliation(s)
- Yaou Ren
- Biochemistry Ph.D. Program, Florida International University, Miami, Florida, United States of America
| | - Yanhao Lai
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Eduardo E. Laverde
- Biochemistry Ph.D. Program, Florida International University, Miami, Florida, United States of America
| | - Ruipeng Lei
- Biochemistry Ph.D. Program, Florida International University, Miami, Florida, United States of America
| | - Hayley L. Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
| | - Yuan Liu
- Biochemistry Ph.D. Program, Florida International University, Miami, Florida, United States of America
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, United States of America
- Biomolecular Sciences Institute, Florida International University, Miami, Florida, United States of America
- * E-mail:
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23
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Yum K, Wang ET, Kalsotra A. Myotonic dystrophy: disease repeat range, penetrance, age of onset, and relationship between repeat size and phenotypes. Curr Opin Genet Dev 2017; 44:30-37. [PMID: 28213156 DOI: 10.1016/j.gde.2017.01.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/11/2016] [Accepted: 01/13/2017] [Indexed: 01/29/2023]
Abstract
Myotonic dystrophy (DM) is an autosomal dominant neuromuscular disease primarily characterized by myotonia and progressive muscle weakness. The pathogenesis of DM involves microsatellite expansions in noncoding regions of transcripts that result in toxic RNA gain-of-function. Each successive generation of DM families carries larger repeat expansions, leading to an earlier age of onset with increasing disease severity. At present, diagnosis of DM is challenging and requires special genetic testing to account for somatic mosaicism and meiotic instability. While progress in genetic testing has been made, more rapid, accurate, and cost-effective approaches for measuring repeat lengths are needed to establish clear correlations between repeat size and disease phenotypes.
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Affiliation(s)
- Kevin Yum
- Department of Biochemistry, University of Illinois, Urbana-Champaign, USA
| | - Eric T Wang
- Department of Molecular Genetics & Microbiology, Center for Neurogenetics, University of Florida, Gainesville, FL 32610, USA.
| | - Auinash Kalsotra
- Department of Biochemistry, University of Illinois, Urbana-Champaign, USA; Institute of Genomic Biology, University of Illinois, Urbana-Champaign, USA.
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24
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Contracting CAG/CTG repeats using the CRISPR-Cas9 nickase. Nat Commun 2016; 7:13272. [PMID: 27827362 PMCID: PMC5105158 DOI: 10.1038/ncomms13272] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/12/2016] [Indexed: 12/15/2022] Open
Abstract
CAG/CTG repeat expansions cause over 13 neurological diseases that remain without a cure. Because longer tracts cause more severe phenotypes, contracting them may provide a therapeutic avenue. No currently known agent can specifically generate contractions. Using a GFP-based chromosomal reporter that monitors expansions and contractions in the same cell population, here we find that inducing double-strand breaks within the repeat tract causes instability in both directions. In contrast, the CRISPR-Cas9 D10A nickase induces mainly contractions independently of single-strand break repair. Nickase-induced contractions depend on the DNA damage response kinase ATM, whereas ATR inhibition increases both expansions and contractions in a MSH2- and XPA-dependent manner. We propose that DNA gaps lead to contractions and that the type of DNA damage present within the repeat tract dictates the levels and the direction of CAG repeat instability. Our study paves the way towards deliberate induction of CAG/CTG repeat contractions in vivo. The expansion of trinucleotide repeats has been linked to several neurodegenerative disorders. Here, the authors show that the CRISPR-Cas9 nuclease induces both expansions and contractions of the repeat region, whereas the nickase leads predominantly to contractions.
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Chatterjee N, Lin Y, Wilson JH. Mismatch repair enhances convergent transcription-induced cell death at trinucleotide repeats by activating ATR. DNA Repair (Amst) 2016; 42:26-32. [PMID: 27131875 DOI: 10.1016/j.dnarep.2016.03.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 03/15/2016] [Accepted: 03/16/2016] [Indexed: 01/08/2023]
Abstract
Trinucleotide repeat (TNR) expansion beyond a certain threshold results in some 20 incurable neurodegenerative disorders where disease anticipation positively correlates with repeat length. Long TNRs typically display a bias toward further expansion during germinal transmission from parents to offspring, and then are highly unstable in somatic tissues of affected individuals. Understanding mechanisms of TNR instability will provide insights into disease pathogenesis. Previously, we showed that enhanced convergent transcription at long CAG repeat tracks induces TNR instability and cell death via ATR activation. Components of TC-NER (transcription-coupled nucleotide excision repair) and RNaseH enzymes that resolve RNA/DNA hybrids oppose cell death, whereas the MSH2 component of MMR (mismatch repair) enhances cell death. The exact role of the MMR pathway during convergent transcription-induced cell death at CAG repeats is not well understood. In this study, we show that siRNA knockdowns of MMR components-MSH2, MSH3, MLHI, PMS2, and PCNA-reduce DNA toxicity. Furthermore, knockdown of MSH2, MLH1, and PMS2 significantly reduces the frequency of ATR foci formation. These observations suggest that MMR proteins activate DNA toxicity by modulating ATR foci formation during convergent transcription.
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Affiliation(s)
- Nimrat Chatterjee
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Yunfu Lin
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX 78957, USA
| | - John H Wilson
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Schaefer MH, Serrano L. Cell type-specific properties and environment shape tissue specificity of cancer genes. Sci Rep 2016; 6:20707. [PMID: 26856619 PMCID: PMC4746590 DOI: 10.1038/srep20707] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/11/2016] [Indexed: 12/21/2022] Open
Abstract
One of the biggest mysteries in cancer research remains why mutations in certain genes cause cancer only at specific sites in the human body. The poor correlation between the expression level of a cancer gene and the tissues in which it causes malignant transformations raises the question of which factors determine the tissue-specific effects of a mutation. Here, we explore why some cancer genes are associated only with few different cancer types (i.e., are specific), while others are found mutated in a large number of different types of cancer (i.e., are general). We do so by contrasting cellular functions of specific-cancer genes with those of general ones to identify properties that determine where in the body a gene mutation is causing malignant transformations. We identified different groups of cancer genes that did not behave as expected (i.e., DNA repair genes being tissue specific, immune response genes showing a bimodal specificity function or strong association of generally expressed genes to particular cancers). Analysis of these three groups demonstrates the importance of environmental impact for understanding why certain cancer genes are only involved in the development of some cancer types but are rarely found mutated in other types of cancer.
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Affiliation(s)
- Martin H Schaefer
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, Barcelona, Spain
| | - Luis Serrano
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, Barcelona, Spain
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Lheureux S, Karakasis K, Kohn EC, Oza AM. Ovarian cancer treatment: The end of empiricism? Cancer 2015; 121:3203-11. [PMID: 26096019 PMCID: PMC4744728 DOI: 10.1002/cncr.29481] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 04/12/2015] [Accepted: 05/05/2015] [Indexed: 01/06/2023]
Abstract
The diagnosis, investigation, and management of ovarian cancer are in a state of flux-balancing ever rapid advances in our understanding of its biology with 3 decades of clinical trials. Clinical trials that started with empirically driven selections have evolved in an evidence-informed manner to gradually improve outcome. Has this improved understanding of the biology and associated calls to action led to appropriate changes in therapy? In this review, the authors discuss incorporating emerging data on biology, combinations, dose, and scheduling of new and existing agents with patient preferences in the management of women with ovarian cancer.
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Affiliation(s)
- Stephanie Lheureux
- Division of Medical Oncology and Hematology, Bras Family Drug Development ProgramPrincess Margaret Cancer CenterTorontoOntarioCanada
| | - Katherine Karakasis
- Division of Medical Oncology and Hematology, Bras Family Drug Development ProgramPrincess Margaret Cancer CenterTorontoOntarioCanada
| | - Elise C. Kohn
- Cancer Therapy Evaluation Program, Division of Cancer Treatment and DiagnosisNational Cancer InstituteBethesdaMaryland
| | - Amit M. Oza
- Division of Medical Oncology and Hematology, Bras Family Drug Development ProgramPrincess Margaret Cancer CenterTorontoOntarioCanada
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Abstract
The demonstration of DNA damage excision and repair replication by Setlow, Howard-Flanders, Hanawalt and their colleagues in the early 1960s, constituted the discovery of the ubiquitous pathway of nucleotide excision repair (NER). The serial steps in NER are similar in organisms from unicellular bacteria to complex mammals and plants, and involve recognition of lesions, adducts or structures that disrupt the DNA double helix, removal of a short oligonucleotide containing the offending lesion, synthesis of a repair patch copying the opposite undamaged strand, and ligation, to restore the DNA to its original form. The transcription-coupled repair (TCR) subpathway of NER, discovered nearly two decades later, is dedicated to the removal of lesions from the template DNA strands of actively transcribed genes. In this review I will outline the essential factors and complexes involved in NER in humans, and will comment on additional factors and metabolic processes that affect the efficiency of this important process.
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Affiliation(s)
- Graciela Spivak
- Department of Biology, Stanford University, Stanford, CA 94305-5020,USA.
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Large expansion of CTG•CAG repeats is exacerbated by MutSβ in human cells. Sci Rep 2015; 5:11020. [PMID: 26047474 PMCID: PMC4457148 DOI: 10.1038/srep11020] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 05/12/2015] [Indexed: 11/08/2022] Open
Abstract
Trinucleotide repeat expansion disorders (TRED) are caused by genomic expansions of trinucleotide repeats, such as CTG and CAG. These expanded repeats are unstable in germline and somatic cells, with potential consequences for disease severity. Previous studies have demonstrated the involvement of DNA repair proteins in repeat instability, although the key factors affecting large repeat expansion and contraction are unclear. Here we investigated these factors in a human cell model harboring 800 CTG•CAG repeats by individually knocking down various DNA repair proteins using short interfering RNA. Knockdown of MSH2 and MSH3, which form the MutSβ heterodimer and function in mismatch repair, suppressed large repeat expansions, whereas knockdown of MSH6, which forms the MutSα heterodimer with MSH2, promoted large expansions exceeding 200 repeats by compensatory increases in MSH3 and the MutSβ complex. Knockdown of topoisomerase 1 (TOP1) and TDP1, which are involved in single-strand break repair, enhanced large repeat contractions. Furthermore, knockdown of senataxin, an RNA/DNA helicase which affects DNA:RNA hybrid formation and transcription-coupled nucleotide excision repair, exacerbated repeat instability in both directions. These results indicate that DNA repair factors, such as MutSβ play important roles in large repeat expansion and contraction, and can be an excellent therapeutic target for TRED.
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Su XA, Dion V, Gasser SM, Freudenreich CH. Regulation of recombination at yeast nuclear pores controls repair and triplet repeat stability. Genes Dev 2015; 29:1006-17. [PMID: 25940904 PMCID: PMC4441049 DOI: 10.1101/gad.256404.114] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 04/10/2015] [Indexed: 12/16/2022]
Abstract
Secondary structure-forming DNA sequences such as CAG repeats interfere with replication and repair, provoking fork stalling, chromosome fragility, and recombination. In budding yeast, Su et al. find that expanded CAG repeats are more likely than unexpanded repeats to localize to the nuclear periphery and that the relocation of damage to nuclear pores plays an important role in a naturally occurring repair process. Secondary structure-forming DNA sequences such as CAG repeats interfere with replication and repair, provoking fork stalling, chromosome fragility, and recombination. In budding yeast, we found that expanded CAG repeats are more likely than unexpanded repeats to localize to the nuclear periphery. This positioning is transient, occurs in late S phase, requires replication, and is associated with decreased subnuclear mobility of the locus. In contrast to persistent double-stranded breaks, expanded CAG repeats at the nuclear envelope associate with pores but not with the inner nuclear membrane protein Mps3. Relocation requires Nup84 and the Slx5/8 SUMO-dependent ubiquitin ligase but not Rad51, Mec1, or Tel1. Importantly, the presence of the Nup84 pore subcomplex and Slx5/8 suppresses CAG repeat fragility and instability. Repeat instability in nup84, slx5, or slx8 mutant cells arises through aberrant homologous recombination and is distinct from instability arising from the loss of ligase 4-dependent end-joining. Genetic and physical analysis of Rad52 sumoylation and binding at the CAG tract suggests that Slx5/8 targets sumoylated Rad52 for degradation at the pore to facilitate recovery from acute replication stress by promoting replication fork restart. We thereby confirmed that the relocation of damage to nuclear pores plays an important role in a naturally occurring repair process.
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Affiliation(s)
- Xiaofeng A Su
- Department of Biology, Tufts University, Medford, Massachusetts 02155, USA
| | - Vincent Dion
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland; Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Catherine H Freudenreich
- Department of Biology, Tufts University, Medford, Massachusetts 02155, USA; Program in Genetics, Tufts University, Medford, Massachusetts 02155, USA;
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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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