101
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Goold R, Flower M, Moss DH, Medway C, Wood-Kaczmar A, Andre R, Farshim P, Bates GP, Holmans P, Jones L, Tabrizi SJ. FAN1 modifies Huntington's disease progression by stabilizing the expanded HTT CAG repeat. Hum Mol Genet 2019; 28:650-661. [PMID: 30358836 PMCID: PMC6360275 DOI: 10.1093/hmg/ddy375] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 11/13/2022] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disease caused by an expanded CAG repeat in the huntingtin (HTT) gene. CAG repeat length explains around half of the variation in age at onset (AAO) but genetic variation elsewhere in the genome accounts for a significant proportion of the remainder. Genome-wide association studies have identified a bidirectional signal on chromosome 15, likely underlain by FANCD2- and FANCI-associated nuclease 1 (FAN1), a nuclease involved in DNA interstrand cross link repair. Here we show that increased FAN1 expression is significantly associated with delayed AAO and slower progression of HD, suggesting FAN1 is protective in the context of an expanded HTT CAG repeat. FAN1 overexpression in human cells reduces CAG repeat expansion in exogenously expressed mutant HTT exon 1, and in patient-derived stem cells and differentiated medium spiny neurons, FAN1 knockdown increases CAG repeat expansion. The stabilizing effects are FAN1 concentration and CAG repeat length-dependent. We show that FAN1 binds to the expanded HTT CAG repeat DNA and its nuclease activity is not required for protection against CAG repeat expansion. These data shed new mechanistic insights into how the genetic modifiers of HD act to alter disease progression and show that FAN1 affects somatic expansion of the CAG repeat through a nuclease-independent mechanism. This provides new avenues for therapeutic interventions in HD and potentially other triplet repeat disorders.
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Affiliation(s)
- Robert Goold
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
| | - Michael Flower
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
| | - Davina Hensman Moss
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
| | - Chris Medway
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, CF24 4HQ, UK
| | - Alison Wood-Kaczmar
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
| | - Ralph Andre
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
| | - Pamela Farshim
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
| | - Gill P Bates
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
- UK Dementia Research Institute, University College London, WC1N 3BG, UK
| | - Peter Holmans
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, CF24 4HQ, UK
| | - Lesley Jones
- Medical Research Council Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, CF24 4HQ, UK
| | - Sarah J Tabrizi
- UCL Huntington’s Disease Centre,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London,Queen Square, London WC1N 3BG, UK
- UK Dementia Research Institute, University College London, WC1N 3BG, UK
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102
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Single-Molecule Sequencing: Towards Clinical Applications. Trends Biotechnol 2019; 37:72-85. [DOI: 10.1016/j.tibtech.2018.07.013] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 07/16/2018] [Accepted: 07/18/2018] [Indexed: 12/31/2022]
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103
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Ren Z, Zhu X, Lv H, Liu H, He H, Zhang X, Wang S. A fluorescent method based on magnetic nanoparticles for detection of CGG trinucleotide repeat genes. NEW J CHEM 2019. [DOI: 10.1039/c8nj04686g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A novel fluorescent sensor based on magnetic nanoparticles as the separator and short report DNA was designed and prepared for the detection of d(CGG)ntrinucleotide repeats. The method exhibited high selectivity and sensitivity, and excellent linear correlation from 100 pM to 150 nM, which is useful for the early diagnosis of neurodegenerative diseases.
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Affiliation(s)
- Ziqi Ren
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
| | - Xiaoqian Zhu
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
| | - Hehong Lv
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
| | - Heng Liu
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
| | - Hanping He
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
| | - Xiuhua Zhang
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
| | - Shengfu Wang
- Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules
- College of Chemistry and Chemical Engineering
- Hubei University
- Youyi Road 368
- Wuchang
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104
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Zhang C, Fu H, Yang Y, Zhou E, Tan Z, You H, Zhang X. The Mechanical Properties of RNA-DNA Hybrid Duplex Stretched by Magnetic Tweezers. Biophys J 2018; 116:196-204. [PMID: 30635125 DOI: 10.1016/j.bpj.2018.12.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 12/05/2018] [Accepted: 12/07/2018] [Indexed: 12/25/2022] Open
Abstract
RNA can anneal to its DNA template to generate an RNA-DNA hybrid (RDH) duplex and a displaced DNA strand, termed R-loop. RDH duplex occupies up to 5% of the mammalian genome and plays important roles in many biological processes. The functions of RDH duplex are affected by its mechanical properties, including the elasticity and the conformation transitions. The mechanical properties of RDH duplex, however, are still unclear. In this work, we studied the mechanical properties of RDH duplex using magnetic tweezers in comparison with those of DNA and RNA duplexes with the same sequences. We report that the contour length of RDH duplex is ∼0.30 nm/bp, and the stretching modulus of RDH duplex is ∼660 pN, neither of which is sensitive to NaCl concentration. The persistence length of RDH duplex depends on NaCl concentration, decreasing from ∼63 nm at 1 mM NaCl to ∼49 nm at 500 mM NaCl. Under high tension of ∼60 pN, the end-opened RDH duplex undergoes two distinct overstretching transitions; at high salt in which the basepairs are stable, it undergoes the nonhysteretic transition, leading to a basepaired elongated structure, whereas at low salt, it undergoes a hysteretic peeling transition, leading to the single-stranded DNA strand under force and the single-stranded RNA strand coils. The peeled RDH is difficult to reanneal back to the duplex conformation, which may be due to the secondary structures formed in the coiled single-stranded RNA strand. These results help us understand the full picture of the structures and mechanical properties of nucleic acid duplexes in solution and provide a baseline for studying the interaction of RDH with proteins at the single-molecule level.
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Affiliation(s)
- Chen Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Hang Fu
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Yajun Yang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Erchi Zhou
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China
| | - Zhijie Tan
- School of Physics and Technology, Wuhan University, Wuhan, China
| | - Huijuan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xinghua Zhang
- College of Life Sciences, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
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105
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Lahiri S, Li Y, Hingorani MM, Mukerji I. MutSγ-Induced DNA Conformational Changes Provide Insights into Its Role in Meiotic Recombination. Biophys J 2018; 115:2087-2101. [PMID: 30467025 DOI: 10.1016/j.bpj.2018.10.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/16/2018] [Accepted: 10/22/2018] [Indexed: 01/11/2023] Open
Abstract
In many organisms, MutSγ plays a role in meiotic recombination, facilitating crossover formation between homologous chromosomes. Failure to form crossovers leads to improper segregation of chromosomes and aneuploidy, which in humans result in infertility and birth defects. To improve current understanding of MutSγ function, this study investigates the binding affinities and structures of MutSγ in complex with DNA substrates that model homologous recombination intermediates. For these studies, we overexpressed and isolated from Escherichia coli the yeast MutSγ protein Saccharomyces cerevisiae (Sc) Msh4-Msh5. Sc Msh4-Msh5 binds Holliday junction (HJ)-like substrates, 3' overhangs, single-stranded (ss) forks, and the displacement loop with nanomolar affinity. The weakest binding affinities are detected for an intact duplex and open-junction construct. Similar to the human protein, Sc Msh4-Msh5 exhibits the highest affinity for the HJ with a Kd < 0.4 nM in solution. Energy-transfer experiments further demonstrate that DNA structure is modulated by the binding interaction with the largest changes associated with substrates containing an ss end. Upon binding, Sc Msh4-Msh5 displaces the ss away from the duplex in most of the ss-containing intermediates, potentially enabling the binding of RPA and other proteins. In the case of the junction-like intermediates, Msh4-Msh5 binding either stabilizes the existing stacked structure or induces formation of the stacked X conformation. Significantly, we find that upon binding, Msh4-Msh5 stacks an open-junction construct to the same extent as the standard junction. Stabilization of the junction in the stacked conformation is generally refractory to branch migration, which is consistent with a potential role for MutSγ to stabilize HJs and prevent branch migration until resolution by MutLγ. The different binding modalities observed suggest that Msh4-Msh5 not only binds to and stabilizes stacked junctions but also participates in meiotic recombination before junction formation through the stabilization of single-end invasion intermediates.
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Affiliation(s)
- Sudipta Lahiri
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Yan Li
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Manju M Hingorani
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Ishita Mukerji
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut.
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106
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Osinalde N, Duarri A, Ramirez J, Barrio R, Perez de Nanclares G, Mayor U. Impaired proteostasis in rare neurological diseases. Semin Cell Dev Biol 2018; 93:164-177. [PMID: 30355526 DOI: 10.1016/j.semcdb.2018.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 10/09/2018] [Accepted: 10/16/2018] [Indexed: 12/19/2022]
Abstract
Rare diseases are classified as such when their prevalence is 1:2000 or lower, but even if each of them is so infrequent, altogether more than 300 million people in the world suffer one of the ∼7000 diseases considered as rare. Over 1200 of these disorders are known to affect the brain or other parts of our nervous system, and their symptoms can affect cognition, motor function and/or social interaction of the patients; we refer collectively to them as rare neurological disorders or RNDs. We have focused this review on RNDs known to have compromised protein homeostasis pathways. Proteostasis can be regulated and/or altered by a chain of cellular mechanisms, from protein synthesis and folding, to aggregation and degradation. Overall, we provide a list comprised of above 215 genes responsible for causing more than 170 distinct RNDs, deepening on some representative diseases, including as well a clinical view of how those diseases are diagnosed and dealt with. Additionally, we review existing methodologies for diagnosis and treatment, discussing the potential of specific deubiquitinating enzyme inhibition as a future therapeutic avenue for RNDs.
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Affiliation(s)
- Nerea Osinalde
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
| | - Anna Duarri
- Barcelona Stem Cell Bank, Center of Regenerative Medicine in Barcelona, 08908 Hospitalet de Llobregat, Barcelona, Spain
| | - Juanma Ramirez
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain
| | - Rosa Barrio
- Functional Genomics Unit, CIC bioGUNE, 48160 Derio, Spain
| | - Guiomar Perez de Nanclares
- Molecular (Epi)Genetics Laboratory, BioAraba National Health Institute, Hospital Universitario Araba-Txagorritxu, Vitoria-Gasteiz, Alava, Spain
| | - Ugo Mayor
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), 48940 Leioa, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
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107
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Hung CLK, Maiuri T, Bowie LE, Gotesman R, Son S, Falcone M, Giordano JV, Gillis T, Mattis V, Lau T, Kwan V, Wheeler V, Schertzer J, Singh K, Truant R. A patient-derived cellular model for Huntington's disease reveals phenotypes at clinically relevant CAG lengths. Mol Biol Cell 2018; 29:2809-2820. [PMID: 30256717 PMCID: PMC6249865 DOI: 10.1091/mbc.e18-09-0590] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The huntingtin protein participates in several cellular processes that are disrupted when the polyglutamine tract is expanded beyond a threshold of 37 CAG DNA repeats in Huntington’s disease (HD). Cellular biology approaches to understand these functional disruptions in HD have primarily focused on cell lines with synthetically long CAG length alleles that clinically represent outliers in this disease and a more severe form of HD that lacks age onset. Patient-derived fibroblasts are limited to a finite number of passages before succumbing to cellular senescence. We used human telomerase reverse transcriptase (hTERT) to immortalize fibroblasts taken from individuals of varying age, sex, disease onset, and CAG repeat length, which we have termed TruHD cells. TruHD cells display classic HD phenotypes of altered morphology, size and growth rate, increased sensitivity to oxidative stress, aberrant adenosine diphosphate/adenosine triphosphate (ADP/ATP) ratios, and hypophosphorylated huntingtin protein. We additionally observed dysregulated reactive oxygen species (ROS)-dependent huntingtin localization to nuclear speckles in HD cells. We report the generation and characterization of a human, clinically relevant cellular model for investigating disease mechanisms in HD at the single-cell level, which, unlike transformed cell lines, maintains functions critical for huntingtin transcriptional regulation and genomic integrity.
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Affiliation(s)
- Claudia Lin-Kar Hung
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Tamara Maiuri
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Laura Erin Bowie
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Ryan Gotesman
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Susie Son
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Mina Falcone
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - James Victor Giordano
- Center for Genomic Medicine, Harvard Medical School, Boston, MA 02114.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Tammy Gillis
- Center for Genomic Medicine, Harvard Medical School, Boston, MA 02114.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Virginia Mattis
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048
| | - Trevor Lau
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Vickie Kwan
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada.,Stem Cell and Cancer Research Institute, Faculty of Health Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Vanessa Wheeler
- Center for Genomic Medicine, Harvard Medical School, Boston, MA 02114.,Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Jonathan Schertzer
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Karun Singh
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Ray Truant
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
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108
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Murmann AE, Yu J, Opal P, Peter ME. Trinucleotide Repeat Expansion Diseases, RNAi, and Cancer. Trends Cancer 2018; 4:684-700. [PMID: 30292352 DOI: 10.1016/j.trecan.2018.08.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 08/23/2018] [Accepted: 08/24/2018] [Indexed: 01/12/2023]
Abstract
Many neurodegenerative diseases are caused by unstable trinucleotide repeat (TNR) expansions located in disease-associated genes. siRNAs based on CAG repeat expansions effectively kill cancer cell lines in vitro through RNAi. They also cause significant reduction in tumor growth in a human ovarian cancer mouse model with no toxicity to the treated mice. This suggests that cancer cells are particularly sensitive to CAG TNR-derived siRNAs, and explains a reported inverse correlation between the length of CAG TNRs and reduced global cancer incidences in some CAG TNR diseases. This review discusses both mutant proteins and mutant RNAs as a cause of TNR diseases, with a focus on RNAi and its role in contributing to disease pathology and in suppressing cancer.
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Affiliation(s)
- Andrea E Murmann
- Department of Medicine, Division Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jindan Yu
- Department of Medicine, Division Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL 60611, USA
| | - Puneet Opal
- Davee Department of Neurology, Northwestern University, Chicago, IL 60611, USA
| | - Marcus E Peter
- Department of Medicine, Division Hematology/Oncology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Biochemistry and Molecular Genetics, Northwestern University, Chicago, IL 60611, USA.
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109
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Gorgoulis VG, Pefani D, Pateras IS, Trougakos IP. Integrating the DNA damage and protein stress responses during cancer development and treatment. J Pathol 2018; 246:12-40. [PMID: 29756349 PMCID: PMC6120562 DOI: 10.1002/path.5097] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 04/16/2018] [Accepted: 05/08/2018] [Indexed: 12/11/2022]
Abstract
During evolution, cells have developed a wide spectrum of stress response modules to ensure homeostasis. The genome and proteome damage response pathways constitute the pillars of this interwoven 'defensive' network. Consequently, the deregulation of these pathways correlates with ageing and various pathophysiological states, including cancer. In the present review, we highlight: (1) the structure of the genome and proteome damage response pathways; (2) their functional crosstalk; and (3) the conditions under which they predispose to cancer. Within this context, we emphasize the role of oncogene-induced DNA damage as a driving force that shapes the cellular landscape for the emergence of the various hallmarks of cancer. We also discuss potential means to exploit key cancer-related alterations of the genome and proteome damage response pathways in order to develop novel efficient therapeutic modalities. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Vassilis G Gorgoulis
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of MedicineNational and Kapodistrian University of AthensAthensGreece
- Biomedical Research Foundation of the Academy of AthensAthensGreece
- Faculty of Biology, Medicine and HealthUniversity of Manchester, Manchester Academic Health Science CentreManchesterUK
| | - Dafni‐Eleftheria Pefani
- CRUK/MRC Institute for Radiation Oncology, Department of OncologyUniversity of OxfordOxfordUK
| | - Ioannis S Pateras
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of MedicineNational and Kapodistrian University of AthensAthensGreece
| | - Ioannis P Trougakos
- Department of Cell Biology and Biophysics, Faculty of BiologyNational and Kapodistrian University of AthensAthensGreece
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110
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Freudenreich CH. R-loops: targets for nuclease cleavage and repeat instability. Curr Genet 2018; 64:789-794. [PMID: 29327083 PMCID: PMC6039234 DOI: 10.1007/s00294-018-0806-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 01/03/2018] [Accepted: 01/08/2018] [Indexed: 01/09/2023]
Abstract
R-loops form when transcribed RNA remains bound to its DNA template to form a stable RNA:DNA hybrid. Stable R-loops form when the RNA is purine-rich, and are further stabilized by DNA secondary structures on the non-template strand. Interestingly, many expandable and disease-causing repeat sequences form stable R-loops, and R-loops can contribute to repeat instability. Repeat expansions are responsible for multiple neurodegenerative diseases, including Huntington's disease, myotonic dystrophy, and several types of ataxias. Recently, it was found that R-loops at an expanded CAG/CTG repeat tract cause DNA breaks as well as repeat instability (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Two factors were identified as causing R-loop-dependent breaks at CAG/CTG tracts: deamination of cytosines and the MutLγ (Mlh1-Mlh3) endonuclease, defining two new mechanisms for how R-loops can generate DNA breaks (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Following R-loop-dependent nicking, base excision repair resulted in repeat instability. These results have implications for human repeat expansion diseases and provide a paradigm for how RNA:DNA hybrids can cause genome instability at structure-forming DNA sequences. This perspective summarizes mechanisms of R-loop-induced fragility at G-rich repeats and new links between DNA breaks and repeat instability.
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Affiliation(s)
- Catherine H Freudenreich
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
- Program in Genetics, Tufts University, Boston, MA, 02111, USA.
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111
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Abstract
Lynch Syndrome (LS) is the most common dominantly inherited colorectal cancer (CRC) predisposition and is caused by a heterozygous germline defect in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, or PMS2. High microsatellite instability (MSI-H) and loss of MMR protein expression in tumours reflecting a defective MMR are indicators for LS, as well as a positive family history of early onset CRC. MSH2 and MSH6 form a major functional heterodimer, and MSH3 is an alternative binding partner for MSH2. So far, the role of germline MSH3 variants remains unclear, as to our knowledge heterozygous truncating variants are not regarded causative for LS, but were detected in patients with CRC, and recently biallelic MSH3 defects have been identified in two patients with adenomatous polyposis. By gene screening we investigated the role of MSH3 in 11 LS patients with truncating MSH6 germline variants and an unexplained MSH2 protein loss in their corresponding MSI-H tumours. We report the first two LS patients harbouring heterozygous germline variants c.1035del and c.2732T>G in MSH3 coincidentally with truncating variants in MSH6. In the patient with truncating germline variants in MSH3 and MSH6, two additional somatic second hits in both genes abrogate all binding partners for the MSH2 protein which might subsequently be degraded. The clinical relevance of MSH3 germline variants is currently under re-evaluation, and heterozygous MSH3 defects alone do not seem to induce a LS phenotype, but might aggravate the MSH6 phenotype in affected family members.
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112
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van Dijk EL, Jaszczyszyn Y, Naquin D, Thermes C. The Third Revolution in Sequencing Technology. Trends Genet 2018; 34:666-681. [PMID: 29941292 DOI: 10.1016/j.tig.2018.05.008] [Citation(s) in RCA: 580] [Impact Index Per Article: 96.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/18/2018] [Accepted: 05/29/2018] [Indexed: 12/16/2022]
Abstract
Forty years ago the advent of Sanger sequencing was revolutionary as it allowed complete genome sequences to be deciphered for the first time. A second revolution came when next-generation sequencing (NGS) technologies appeared, which made genome sequencing much cheaper and faster. However, NGS methods have several drawbacks and pitfalls, most notably their short reads. Recently, third-generation/long-read methods appeared, which can produce genome assemblies of unprecedented quality. Moreover, these technologies can directly detect epigenetic modifications on native DNA and allow whole-transcript sequencing without the need for assembly. This marks the third revolution in sequencing technology. Here we review and compare the various long-read methods. We discuss their applications and their respective strengths and weaknesses and provide future perspectives.
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Affiliation(s)
- Erwin L van Dijk
- Institute for Integrative Biology of the Cell, UMR9198, CNRS CEA Université Paris-Sud, Université Paris-Saclay, 9198 Gif sur Yvette Cedex, France.
| | - Yan Jaszczyszyn
- Institute for Integrative Biology of the Cell, UMR9198, CNRS CEA Université Paris-Sud, Université Paris-Saclay, 9198 Gif sur Yvette Cedex, France
| | - Delphine Naquin
- Institute for Integrative Biology of the Cell, UMR9198, CNRS CEA Université Paris-Sud, Université Paris-Saclay, 9198 Gif sur Yvette Cedex, France
| | - Claude Thermes
- Institute for Integrative Biology of the Cell, UMR9198, CNRS CEA Université Paris-Sud, Université Paris-Saclay, 9198 Gif sur Yvette Cedex, France
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113
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André LM, Ausems CRM, Wansink DG, Wieringa B. Abnormalities in Skeletal Muscle Myogenesis, Growth, and Regeneration in Myotonic Dystrophy. Front Neurol 2018; 9:368. [PMID: 29892259 PMCID: PMC5985300 DOI: 10.3389/fneur.2018.00368] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/07/2018] [Indexed: 12/16/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and 2 (DM2) are autosomal dominant degenerative neuromuscular disorders characterized by progressive skeletal muscle weakness, atrophy, and myotonia with progeroid features. Although both DM1 and DM2 are characterized by skeletal muscle dysfunction and also share other clinical features, the diseases differ in the muscle groups that are affected. In DM1, distal muscles are mainly affected, whereas in DM2 problems are mostly found in proximal muscles. In addition, manifestation in DM1 is generally more severe, with possible congenital or childhood-onset of disease and prominent CNS involvement. DM1 and DM2 are caused by expansion of (CTG•CAG)n and (CCTG•CAGG)n repeats in the 3' non-coding region of DMPK and in intron 1 of CNBP, respectively, and in overlapping antisense genes. This critical review will focus on the pleiotropic problems that occur during development, growth, regeneration, and aging of skeletal muscle in patients who inherited these expansions. The current best-accepted idea is that most muscle symptoms can be explained by pathomechanistic effects of repeat expansion on RNA-mediated pathways. However, aberrations in DNA replication and transcription of the DM loci or in protein translation and proteome homeostasis could also affect the control of proliferation and differentiation of muscle progenitor cells or the maintenance and physiological integrity of muscle fibers during a patient's lifetime. Here, we will discuss these molecular and cellular processes and summarize current knowledge about the role of embryonic and adult muscle-resident stem cells in growth, homeostasis, regeneration, and premature aging of healthy and diseased muscle tissue. Of particular interest is that also progenitor cells from extramuscular sources, such as pericytes and mesoangioblasts, can participate in myogenic differentiation. We will examine the potential of all these types of cells in the application of regenerative medicine for muscular dystrophies and evaluate new possibilities for their use in future therapy of DM.
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Affiliation(s)
- Laurène M André
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - C Rosanne M Ausems
- Department of Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, Netherlands
| | - Derick G Wansink
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Bé Wieringa
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
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114
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Locus specific engineering of tandem DNA repeats in the genome of Saccharomyces cerevisiae using CRISPR/Cas9 and overlapping oligonucleotides. Sci Rep 2018; 8:7127. [PMID: 29740109 PMCID: PMC5940919 DOI: 10.1038/s41598-018-25508-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 04/23/2018] [Indexed: 11/12/2022] Open
Abstract
DNA repeats constitute a large part of genomes of multicellular eucaryotes. For a longtime considered as junk DNA, their role in genome organization and tuning of gene expression is being increasingly documented. Synthetic biology has so far largely ignored DNA repeats as regulatory elements to manipulate functions in engineered genomes. The yeast Saccharomyces cerevisiae has been a workhorse of synthetic biology, owing to its genetic tractability. Here we demonstrate the ability to synthetize, in a simple manner, tandem DNA repeats of various size by Cas9-assisted oligonucleotide in vivo assembly in this organism. We show that long tandem DNA repeats of several kilobases can be assembled in one step for different monomer size and G/C content. The combinatorial nature of the approach allows exploring a wide variety of design for building synthetic tandem repeated DNA directly at a given locus in the Saccharomyces cerevisiae genome. This approach provides a simple way to incorporate tandem DNA repeat in synthetic genome designs to implement regulatory functions.
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115
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Kramara J, Osia B, Malkova A. Break-Induced Replication: The Where, The Why, and The How. Trends Genet 2018; 34:518-531. [PMID: 29735283 DOI: 10.1016/j.tig.2018.04.002] [Citation(s) in RCA: 171] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 02/27/2018] [Accepted: 04/05/2018] [Indexed: 01/07/2023]
Abstract
Break-induced replication (BIR) is a pathway that repairs one-ended double-strand breaks (DSBs). For decades, yeast model systems offered the only opportunities to study eukaryotic BIR. These studies described an unusual mode of BIR synthesis that is carried out by a migrating bubble and shows conservative inheritance of newly synthesized DNA, leading to genomic instabilities like those associated with cancer in humans. Yet, evidence of BIR functioning in mammals or during repair of other DNA breaks has been missing. Recent studies have uncovered multiple examples of BIR working in replication restart and repair of eroded telomeres in yeast and mammals, as well as some unexpected findings, including the RAD51 independence of BIR. Strong interest remains in determining the variations in molecular mechanisms that drive and regulate BIR in different genetic backgrounds, across organisms, and particularly in the context of human disease.
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Affiliation(s)
- J Kramara
- These authors contributed equally to this work
| | - B Osia
- These authors contributed equally to this work
| | - A Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA.
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116
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Holmans PA, Massey TH, Jones L. Genetic modifiers of Mendelian disease: Huntington's disease and the trinucleotide repeat disorders. Hum Mol Genet 2018; 26:R83-R90. [PMID: 28977442 DOI: 10.1093/hmg/ddx261] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 07/03/2017] [Indexed: 02/06/2023] Open
Abstract
In the decades since the genes and mutations associated with the commoner Mendelian disorders were first discovered, technological advances in genetic analysis have made finding genomic variation a much less onerous task. Recently, the global efforts to collect subjects with Mendelian disorders, to better define the disorders and to empower appropriate clinical trials, along with improved genetic technologies, have allowed the identification of genetic variation that does not cause disease, but substantially modifies disease presentation. The advantage of this is it identifies biological pathways and molecules, that, if modified in people, might alter disease presentation. In Huntington's disease (HD), caused by an expanded CAG repeat tract in HTT, genetic variation has been uncovered that is associated with change in the onset or progression of disease. Some of this variation lies in genes that are part of the DNA damage response, previously suggested to be important in modulating expansion of the repeat tract in germline and somatic cells. The genetic evidence implicates a DNA damage response-related pathway in modulating the pathogenicity of the repeat tracts in HD, and possibly, in other trinucleotide repeat disorders. These findings offer new targets for drug development in these currently intractable disorders.
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Affiliation(s)
- Peter A Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neuroscience, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Thomas H Massey
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neuroscience, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Division of Psychological Medicine and Clinical Neuroscience, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
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117
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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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118
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Chen X, Sun YZ, Zhang DH, Li JQ, Yan GY, An JY, You ZH. NRDTD: a database for clinically or experimentally supported non-coding RNAs and drug targets associations. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2018; 2017:4027556. [PMID: 29220444 PMCID: PMC5527270 DOI: 10.1093/database/bax057] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 06/30/2017] [Indexed: 11/14/2022]
Abstract
In recent years, more and more non-coding RNAs (ncRNAs) have been identified and increasing evidences have shown that ncRNAs may affect gene expression and disease progression, making them a new class of targets for drug discovery. It thus becomes important to understand the relationship between ncRNAs and drug targets. For this purpose, an ncRNAs and drug targets association database would be extremely beneficial. Here, we developed ncRNA Drug Targets Database (NRDTD) that collected 165 entries of clinically or experimentally supported ncRNAs as drug targets, including 97 ncRNAs and 96 drugs. Moreover, we annotated ncRNA-drug target associations with drug information from KEGG, PubChem, DrugBank, CTD or Wikipedia, GenBank sequence links, OMIM disease ID, pathway and function annotation for ncRNAs, detailed description of associations between ncRNAs and diseases from HMDD or LncRNADisease and the publication PubMed ID. Additionally, we provided users a link to submit novel disease-ncRNA-drug associations and corresponding supporting evidences into the database. We hope NRDTD will be a useful resource for investigating the roles of ncRNAs in drug target identification, drug discovery and disease treatment. Database URL:http://chengroup.cumt.edu.cn/NRDTD
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Affiliation(s)
- Xing Chen
- School of Information and Control Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Ya-Zhou Sun
- College of Computer Science and Software Engineering, Shenzhen University, Shenzhen 518060, China
| | - De-Hong Zhang
- School of Information and Control Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Jian-Qiang Li
- College of Computer Science and Software Engineering, Shenzhen University, Shenzhen 518060, China
| | - Gui-Ying Yan
- Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190, China
| | - Ji-Yong An
- School of Computer Science and Technology, China University of Mining and Technology, Xuzhou 21116, China
| | - Zhu-Hong You
- Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Science, Urumqi 830011, China
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119
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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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120
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Abstract
More than 40 diseases, most of which primarily affect the nervous system, are caused by expansions of simple sequence repeats dispersed throughout the human genome. Expanded trinucleotide repeat diseases were discovered first and remain the most frequent. More recently tetra-, penta-, hexa-, and even dodeca-nucleotide repeat expansions have been identified as the cause of human disease, including some of the most common genetic disorders seen by neurologists. Repeat expansion diseases include both causes of myotonic dystrophy (DM1 and DM2), the most common genetic cause of amyotrophic lateral sclerosis/frontotemporal dementia (C9ORF72), Huntington disease, and eight other polyglutamine disorders, including the most common forms of dominantly inherited ataxia, the most common recessive ataxia (Friedreich ataxia), and the most common heritable mental retardation (fragile X syndrome). Here I review distinctive features of this group of diseases that stem from the unusual, dynamic nature of the underlying mutations. These features include marked clinical heterogeneity and the phenomenon of clinical anticipation. I then discuss the diverse molecular mechanisms driving disease pathogenesis, which vary depending on the repeat sequence, size, and location within the disease gene, and whether the repeat is translated into protein. I conclude with a brief clinical and genetic description of individual repeat expansion diseases that are most relevant to neurologists.
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Affiliation(s)
- Henry Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States.
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121
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Abstract
Huntington's disease (HD) is caused by a CAG repeat expansion in the HTT gene. Repeat length can change over time, both in individual cells and between generations, and longer repeats may drive pathology. Cellular DNA repair systems have long been implicated in CAG repeat instability but recent genetic evidence from humans linking DNA repair variants to HD onset and progression has reignited interest in this area. The DNA damage response plays an essential role in maintaining genome stability, but may also license repeat expansions in the context of HD. In this chapter we summarize the methods developed to assay CAG repeat expansion/contraction in vitro and in cells, and review the DNA repair genes tested in mouse models of HD. While none of these systems is currently ideal, new technologies, such as long-read DNA sequencing, should improve the sensitivity of assays to assess the effects of DNA repair pathways in HD. Improved assays will be essential precursors to high-throughput testing of small molecules that can alter specific steps in DNA repair pathways and perhaps ameliorate expansion or enhance contraction of the HTT CAG repeat.
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122
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Williams GM, Surtees JA. Measuring Dynamic Behavior of Trinucleotide Repeat Tracts In Vivo in Saccharomyces cerevisiae. Methods Mol Biol 2018; 1672:439-470. [PMID: 29043641 DOI: 10.1007/978-1-4939-7306-4_30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Trinucleotide repeat (TNR) tracts are inherently unstable during DNA replication, leading to repeat expansions and/or contractions. Expanded tracts are the cause of over 40 neurodegenerative and neuromuscular diseases. In this chapter, we focus on the (CNG)n repeat sequences that, when expanded, lead to Huntington's disease (HD), myotonic dystrophy type 1 (DM1), and a number of other neurodegenerative diseases. We describe a series of in vivo assays, using the model system Saccharomyces cerevisiae, to determine and characterize the dynamic behavior of TNR tracts that are in the early stages of expansion, i.e., the so-called threshold range. Through a series of time courses and PCR-based assays, dynamic changes in tract length can be observed as a function of time. These assays can ultimately be used to determine how genetic factors influence the process of tract expansion in these early stages.
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Affiliation(s)
- Gregory M Williams
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, 14214, USA
| | - Jennifer A Surtees
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, 14214, USA. .,Genetics, Genomics and Bioinformatics Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY, 14214, USA.
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123
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Disease onset in X-linked dystonia-parkinsonism correlates with expansion of a hexameric repeat within an SVA retrotransposon in TAF1. Proc Natl Acad Sci U S A 2017; 114:E11020-E11028. [PMID: 29229810 PMCID: PMC5754783 DOI: 10.1073/pnas.1712526114] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The genetic basis of X-Linked dystonia-parkinsonism (XDP) has been difficult to unravel, in part because all patients inherit the same haplotype of seven sequence variants, none of which has ever been identified in control individuals. This study revealed that one of the haplotype markers, a retrotransposon insertion within an intron of TAF1, has a variable number of hexameric repeats among affected individuals with an increase in repeat number strongly correlated with earlier age at disease onset. These data support a contributing role for this sequence in disease pathogenesis while further suggesting that XDP may be part of a growing list of neurodegenerative disorders associated with unstable repeat expansions. X-linked dystonia-parkinsonism (XDP) is a neurodegenerative disease associated with an antisense insertion of a SINE-VNTR-Alu (SVA)-type retrotransposon within an intron of TAF1. This unique insertion coincides with six additional noncoding sequence changes in TAF1, the gene that encodes TATA-binding protein–associated factor-1, which appear to be inherited together as an identical haplotype in all reported cases. Here we examined the sequence of this SVA in XDP patients (n = 140) and detected polymorphic variation in the length of a hexanucleotide repeat domain, (CCCTCT)n. The number of repeats in these cases ranged from 35 to 52 and showed a highly significant inverse correlation with age at disease onset. Because other SVAs exhibit intrinsic promoter activity that depends in part on the hexameric domain, we assayed the transcriptional regulatory effects of varying hexameric lengths found in the unique XDP SVA retrotransposon using luciferase reporter constructs. When inserted sense or antisense to the luciferase reading frame, the XDP variants repressed or enhanced transcription, respectively, to an extent that appeared to vary with length of the hexamer. Further in silico analysis of this SVA sequence revealed multiple motifs predicted to form G-quadruplexes, with the greatest potential detected for the hexameric repeat domain. These data directly link sequence variation within the XDP-specific SVA sequence to phenotypic variability in clinical disease manifestation and provide insight into potential mechanisms by which this intronic retroelement may induce transcriptional interference in TAF1 expression.
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124
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Guo J, Chen L, Li GM. DNA mismatch repair in trinucleotide repeat instability. SCIENCE CHINA. LIFE SCIENCES 2017; 60:1087-1092. [PMID: 29075942 DOI: 10.1007/s11427-017-9186-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 09/30/2017] [Indexed: 11/29/2022]
Abstract
Trinucleotide repeat expansions cause over 30 severe neuromuscular and neurodegenerative disorders, including Huntington's disease, myotonic dystrophy type 1, and fragile X syndrome. Although previous studies have substantially advanced the understanding of the disease biology, many key features remain unknown. DNA mismatch repair (MMR) plays a critical role in genome maintenance by removing DNA mismatches generated during DNA replication. However, MMR components, particularly mismatch recognition protein MutSβ and its interacting factors MutLα and MutLγ, have been implicated in trinucleotide repeat instability. In this review, we will discuss the roles of these key MMR proteins in promoting trinucleotide repeat instability.
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Affiliation(s)
- Jinzhen Guo
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Luping Chen
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, CA, 90033, USA
| | - Guo-Min Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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125
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Kramara J, Osia B, Malkova A. Break-induced replication: an unhealthy choice for stress relief? Nat Struct Mol Biol 2017; 24:11-12. [PMID: 28054567 DOI: 10.1038/nsmb.3361] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Juraj Kramara
- Department of Biology, University of Iowa, Iowa City, Iowa, USA
| | - Beth Osia
- Department of Biology, University of Iowa, Iowa City, Iowa, USA
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, Iowa, USA
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126
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Pathways and Mechanisms that Prevent Genome Instability in Saccharomyces cerevisiae. Genetics 2017; 206:1187-1225. [PMID: 28684602 PMCID: PMC5500125 DOI: 10.1534/genetics.112.145805] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 04/26/2017] [Indexed: 12/13/2022] Open
Abstract
Genome rearrangements result in mutations that underlie many human diseases, and ongoing genome instability likely contributes to the development of many cancers. The tools for studying genome instability in mammalian cells are limited, whereas model organisms such as Saccharomyces cerevisiae are more amenable to these studies. Here, we discuss the many genetic assays developed to measure the rate of occurrence of Gross Chromosomal Rearrangements (called GCRs) in S. cerevisiae. These genetic assays have been used to identify many types of GCRs, including translocations, interstitial deletions, and broken chromosomes healed by de novo telomere addition, and have identified genes that act in the suppression and formation of GCRs. Insights from these studies have contributed to the understanding of pathways and mechanisms that suppress genome instability and how these pathways cooperate with each other. Integrated models for the formation and suppression of GCRs are discussed.
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127
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Auboeuf D. Genome evolution is driven by gene expression-generated biophysical constraints through RNA-directed genetic variation: A hypothesis. Bioessays 2017; 39. [DOI: 10.1002/bies.201700069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Didier Auboeuf
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210; Laboratory of Biology and Modelling of the Cell; Site Jacques Monod; Lyon France
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128
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Identification of genetic modifiers of somatic CAG instability in Huntington's Disease by in vivo CRISPR – Cas9 genome editing. Porto Biomed J 2017; 2:209-210. [DOI: 10.1016/j.pbj.2017.07.083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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129
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Identifying modifiers of Huntington's disease progression. Lancet Neurol 2017. [DOI: 10.1016/s1474-4422(17)30179-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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130
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Rohilla KJ, Gagnon KT. RNA biology of disease-associated microsatellite repeat expansions. Acta Neuropathol Commun 2017; 5:63. [PMID: 28851463 PMCID: PMC5574247 DOI: 10.1186/s40478-017-0468-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/22/2017] [Indexed: 12/13/2022] Open
Abstract
Microsatellites, or simple tandem repeat sequences, occur naturally in the human genome and have important roles in genome evolution and function. However, the expansion of microsatellites is associated with over two dozen neurological diseases. A common denominator among the majority of these disorders is the expression of expanded tandem repeat-containing RNA, referred to as xtrRNA in this review, which can mediate molecular disease pathology in multiple ways. This review focuses on the potential impact that simple tandem repeat expansions can have on the biology and metabolism of RNA that contain them and underscores important gaps in understanding. Merging the molecular biology of repeat expansion disorders with the current understanding of RNA biology, including splicing, transcription, transport, turnover and translation, will help clarify mechanisms of disease and improve therapeutic development.
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131
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Pećina-Šlaus N, Kafka A, Bukovac A, Vladušić T, Tomas D, Hrašćan R. Genetic changes of MLH1 and MSH2 genes could explain constant findings on microsatellite instability in intracranial meningioma. Tumour Biol 2017; 39:1010428317705791. [PMID: 28705114 DOI: 10.1177/1010428317705791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Postreplicative mismatch repair safeguards the stability of our genome. The defects in its functioning will give rise to microsatellite instability. In this study, 50 meningiomas were investigated for microsatellite instability. Two major mismatch repair genes, MLH1 and MSH2, were analyzed using microsatellite markers D1S1611 and BAT26 amplified by polymerase chain reaction and visualized by gel electrophoresis on high-resolution gels. Furthermore, genes DVL3 (D3S1262), AXIN1 (D16S3399), and CDH1 (D16S752) were also investigated for microsatellite instability. Our study revealed constant presence of microsatellite instability in meningioma patients when compared to their autologous blood DNA. Altogether 38% of meningiomas showed microsatellite instability at one microsatellite locus, 16% on two, and 13.3% on three loci. The percent of detected microsatellite instability for MSH2 gene was 14%, and for MLH1, it was 26%, for DVL3 22.9%, for AXIN1 17.8%, and for CDH1 8.3%. Since markers also allowed for the detection of loss of heterozygosity, gross deletions of MLH1 gene were found in 24% of meningiomas. Genetic changes between MLH1 and MSH2 were significantly positively correlated (p = 0.032). We also noted a positive correlation between genetic changes of MSH2 and DVL3 genes (p = 0.034). No significant associations were observed when MLH1 or MSH2 was tested against specific histopathological meningioma subtype or World Health Organization grade. However, genetic changes in DVL3 were strongly associated with anaplastic histology of meningioma (χ2 = 9.14; p = 0.01). Our study contributes to better understanding of the genetic profile of human intracranial meningiomas and suggests that meningiomas harbor defective cellular DNA mismatch repair mechanisms.
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Affiliation(s)
- Nives Pećina-Šlaus
- 1 Laboratory of Neurooncology, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.,2 Department of Biology, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Anja Kafka
- 1 Laboratory of Neurooncology, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.,2 Department of Biology, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Anja Bukovac
- 1 Laboratory of Neurooncology, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.,2 Department of Biology, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Tomislav Vladušić
- 3 Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Zagreb, Croatia
| | - Davor Tomas
- 4 Department of Pathology, School of Medicine, University of Zagreb, Zagreb, Croatia.,5 University Hospital "Sisters of Charity," Zagreb, Croatia
| | - Reno Hrašćan
- 3 Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Zagreb, Croatia
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132
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Liu Q, Zhang P, Wang D, Gu W, Wang K. Interrogating the "unsequenceable" genomic trinucleotide repeat disorders by long-read sequencing. Genome Med 2017; 9:65. [PMID: 28720120 PMCID: PMC5514472 DOI: 10.1186/s13073-017-0456-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 06/30/2017] [Indexed: 12/26/2022] Open
Abstract
Microsatellite expansion, such as trinucleotide repeat expansion (TRE), is known to cause a number of genetic diseases. Sanger sequencing and next-generation short-read sequencing are unable to interrogate TRE reliably. We developed a novel algorithm called RepeatHMM to estimate repeat counts from long-read sequencing data. Evaluation on simulation data, real amplicon sequencing data on two repeat expansion disorders, and whole-genome sequencing data generated by PacBio and Oxford Nanopore technologies showed superior performance over competing approaches. We concluded that long-read sequencing coupled with RepeatHMM can estimate repeat counts on microsatellites and can interrogate the “unsequenceable” genomic trinucleotide repeat disorders.
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Affiliation(s)
- Qian Liu
- Institute for Genomic Medicine, Columbia University, New York, NY, 10032, USA
| | - Peng Zhang
- Nextomics Biosciences, Wuhan, Hubei, 430000, China
| | - Depeng Wang
- Nextomics Biosciences, Wuhan, Hubei, 430000, China
| | - Weihong Gu
- China-Japan Friendship Hospital, Beijing, 100029, China
| | - Kai Wang
- Institute for Genomic Medicine, Columbia University, New York, NY, 10032, USA. .,Department of Biomedical Informatics, Columbia University, New York, NY, 10032, USA.
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133
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The impact of replication stress on replication dynamics and DNA damage in vertebrate cells. Nat Rev Genet 2017; 18:535-550. [DOI: 10.1038/nrg.2017.46] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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134
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Abstract
In this review, we discuss how two evolutionarily conserved pathways at the interface of DNA replication and repair, template switching and break-induced replication, lead to the deleterious large-scale expansion of trinucleotide DNA repeats that cause numerous hereditary diseases. We highlight that these pathways, which originated in prokaryotes, may be subsequently hijacked to maintain long DNA microsatellites in eukaryotes. We suggest that the negative mutagenic outcomes of these pathways, exemplified by repeat expansion diseases, are likely outweighed by their positive role in maintaining functional repetitive regions of the genome such as telomeres and centromeres.
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Affiliation(s)
| | - Jane C Kim
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, USA
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135
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Patro LPP, Kumar A, Kolimi N, Rathinavelan T. 3D-NuS: A Web Server for Automated Modeling and Visualization of Non-Canonical 3-Dimensional Nucleic Acid Structures. J Mol Biol 2017; 429:2438-2448. [PMID: 28652006 DOI: 10.1016/j.jmb.2017.06.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 06/15/2017] [Accepted: 06/15/2017] [Indexed: 10/19/2022]
Abstract
The inherent conformational flexibility of nucleic acids facilitates the formation of a range of conformations such as duplex, triplex, quadruplex, etc. that play crucial roles in biological processes. Elucidation of the influence of non-canonical base pair mismatches on DNA/RNA structures at different sequence contexts to understand the mismatch repair, misregulation of alternative splicing mechanisms and the sequence-dependent effect of RNA-DNA hybrid in relevance to antisense strategy demand their three-dimensional structural information. Furthermore, structural insights about nucleic acid triplexes, which are generally not tractable to structure determination by X-ray crystallography or NMR techniques, are essential to establish their biological function(s). A web server, namely 3D-NuS (http://iith.ac.in/3dnus/), has been developed to generate energy-minimized models of 80 different types of triplexes, 64 types of G-quadruplexes, left-handed Z-DNA/RNA duplexes, and RNA-DNA hybrid duplex along with inter- and intramolecular DNA or RNA duplexes comprising a variety of mismatches and their chimeric forms for any user-defined sequence and length. It also generates an ensemble of conformations corresponding to the modeled structure. These structures may serve as good starting models for docking proteins and small molecules with nucleic acids, NMR structure determination, cryo-electron microscope modeling, DNA/RNA nanotechnology applications and molecular dynamics simulation studies.
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Affiliation(s)
- L Ponoop Prasad Patro
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana State 502285, India
| | - Abhishek Kumar
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana State 502285, India
| | - Narendar Kolimi
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana State 502285, India
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136
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Abstract
The instability of microsatellite DNA repeats is responsible for at least 40 neurodegenerative diseases. Recently, Mirkin and co-workers presented a novel mechanism for microsatellite expansions based on break-induced replication (BIR) at sites of microsatellite-induced replication stalling and fork collapse. The BIR model aims to explain single-step, large expansions of CAG/CTG trinucleotide repeats in dividing cells. BIR has been characterized extensively in Saccharomyces cerevisiae as a mechanism to repair broken DNA replication forks (single-ended DSBs) and degraded telomeric DNA. However, the structural footprints of BIR-like DSB repair have been recognized in human genomic instability and tied to the etiology of diverse developmental diseases; thus, the implications of the paper by Kim et al. (Kim JC, Harris ST, Dinter T, Shah KA, et al., Nat Struct Mol Biol 24: 55-60) extend beyond trinucleotide repeat expansion in yeast and microsatellite instability in human neurological disorders. Significantly, insight into BIR-like repair can explain certain pathways of complex genome rearrangements (CGRs) initiated at non-B form microsatellite DNA in human cancers.
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Affiliation(s)
- Michael Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
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137
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Kim Y, de la Torre A, Leal AA, Finkelstein IJ. Efficient modification of λ-DNA substrates for single-molecule studies. Sci Rep 2017; 7:2071. [PMID: 28522818 PMCID: PMC5437064 DOI: 10.1038/s41598-017-01984-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 04/05/2017] [Indexed: 01/15/2023] Open
Abstract
Single-molecule studies of protein-nucleic acid interactions frequently require site-specific modification of long DNA substrates. The bacteriophage λ is a convenient source of high quality long (48.5 kb) DNA. However, introducing specific sequences, tertiary structures, and chemical modifications into λ-DNA remains technically challenging. Most current approaches rely on multi-step ligations with low yields and incomplete products. Here, we describe a molecular toolkit for rapid preparation of modified λ-DNA. A set of PCR cassettes facilitates the introduction of recombinant DNA sequences into the λ-phage genome with 90-100% yield. Extrahelical structures and chemical modifications can be inserted at user-defined sites via an improved nicking enzyme-based strategy. As a proof-of-principle, we explore the interactions of S. cerevisiae Proliferating Cell Nuclear Antigen (yPCNA) with modified DNA sequences and structures incorporated within λ-DNA. Our results demonstrate that S. cerevisiae Replication Factor C (yRFC) can load yPCNA onto 5'-ssDNA flaps, (CAG)13 triplet repeats, and homoduplex DNA. However, yPCNA remains trapped on the (CAG)13 structure, confirming a proposed mechanism for triplet repeat expansion. We anticipate that this molecular toolbox will be broadly useful for other studies that require site-specific modification of long DNA substrates.
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Affiliation(s)
- Yoori Kim
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Armando de la Torre
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Andrew A Leal
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, 78712, USA.
- Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, 78712, USA.
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138
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Morriss GR, Cooper TA. Protein sequestration as a normal function of long noncoding RNAs and a pathogenic mechanism of RNAs containing nucleotide repeat expansions. Hum Genet 2017; 136:1247-1263. [PMID: 28484853 DOI: 10.1007/s00439-017-1807-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 04/28/2017] [Indexed: 12/12/2022]
Abstract
An emerging class of long noncoding RNAs (lncRNAs) function as decoy molecules that bind and sequester proteins thereby inhibiting their normal functions. Titration of proteins by lncRNAs has wide-ranging effects affecting nearly all steps in gene expression. While decoy lncRNAs play a role in normal physiology, RNAs expressed from alleles containing nucleotide repeat expansions can be pathogenic due to protein sequestration resulting in disruption of normal functions. This review focuses on commonalities between decoy lncRNAs that regulate gene expression by competitive inhibition of protein function through sequestration and specific examples of nucleotide repeat expansion disorders mediated by toxic RNA that sequesters RNA-binding proteins and impedes their normal functions. Understanding how noncoding RNAs compete with various RNA and DNA molecules for binding of regulatory proteins will provide insight into how similar mechanisms contribute to disease pathogenesis.
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Affiliation(s)
- Ginny R Morriss
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Thomas A Cooper
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, 77030, USA.
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139
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Sakofsky CJ, Malkova A. Break induced replication in eukaryotes: mechanisms, functions, and consequences. Crit Rev Biochem Mol Biol 2017; 52:395-413. [PMID: 28427283 DOI: 10.1080/10409238.2017.1314444] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Break-induced replication (BIR) is an important pathway specializing in repair of one-ended double-strand DNA breaks (DSBs). This type of DSB break typically arises at collapsed replication forks or at eroded telomeres. BIR initiates by invasion of a broken DNA end into a homologous template followed by initiation of DNA synthesis that can proceed for hundreds of kilobases. This synthesis is drastically different from S-phase replication in that instead of a replication fork, BIR proceeds via a migrating bubble and is associated with conservative inheritance of newly synthesized DNA. This unusual mode of DNA replication is responsible for frequent genetic instabilities associated with BIR, including hyper-mutagenesis, which can lead to the formation of mutation clusters, extensive loss of heterozygosity, chromosomal translocations, copy-number variations and complex genomic rearrangements. In addition to budding yeast experimental systems that were initially employed to investigate eukaryotic BIR, recent studies in different organisms including humans, have provided multiple examples of BIR initiated within different cellular contexts, including collapsed replication fork and telomere maintenance in the absence of telomerase. In addition, significant progress has been made towards understanding microhomology-mediated BIR (MMBIR) that can promote complex chromosomal rearrangements, including those associated with cancer and those leading to a number of neurological disorders in humans.
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Affiliation(s)
- Cynthia J Sakofsky
- a Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences , US National Institutes of Health , Research Triangle Park , NC , USA
| | - Anna Malkova
- b Department of Biology , University of Iowa , Iowa City , IA , USA
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140
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Hinrichsen I, Ackermann A, Düding T, Graband A, Filmann N, Plotz G, Zeuzem S, Brieger A. Loss of MLH1 sensitizes colon cancer cells to DNA-PKcs inhibitor KU60648. Mol Carcinog 2017; 56:1816-1824. [PMID: 28224663 DOI: 10.1002/mc.22640] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 01/30/2017] [Accepted: 02/16/2017] [Indexed: 12/15/2022]
Abstract
Germline mutations of MLH1 are responsible for tumor generation in nearly 50% of patients with Lynch Syndrome, and around 15% of sporadic colorectal cancers show MLH1-deficiency due to promotor hypermethylation. Although these tumors are of lower aggressiveness the benefit for these patients from standard chemotherapy is still under discussion. Recently, it was shown that the sensitivity to the DNA-PKcs inhibitor KU60648 is linked to loss of the MMR protein MSH3. However, loss of MSH3 is rather secondary, as a consequence of MMR-deficiency, and frequently detectable in MLH1-deficient tumors. Therefore, we examined the expression of MLH1, MSH2, MSH6, and MSH3 in different MMR-deficient and proficient cell lines and determined their sensitivity to KU60648 by analyzing cell viability and survival. MLH1-dependent ability of double strand break (DSB) repair was monitored after irradiation via γH2AX detection. A panel of 12 colon cancer cell lines, two pairs of cells, where MLH1 knock down was compared to controls with the same genetic background, and one MLH1-deficient cell line where MLH1 was overexpressed, were included. In summary, we found that MLH1 and/or MSH3-deficient cells exhibited a significantly higher sensitivity to KU60648 than MMR-proficient cells and that overexpression of MLH1 in MLH1-deficient cells resulted in a decrease of cell sensitivity. KU60648 efficiency seems to be associated with reduced DSB repair capacity. Since the molecular testing of colon tumors for MLH1 expression is a clinical standard we believe that MLH1 is a much better marker and a greater number of patients would benefit from KU60648 treatment.
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Affiliation(s)
- Inga Hinrichsen
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Anne Ackermann
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Tonja Düding
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Annika Graband
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Natalie Filmann
- Institute of Biostatistics and Mathematical Modeling, Goethe University Frankfurt, Germany
| | - Guido Plotz
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Stefan Zeuzem
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
| | - Angela Brieger
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a.M., Germany
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141
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Barbé L, Lanni S, López-Castel A, Franck S, Spits C, Keymolen K, Seneca S, Tomé S, Miron I, Letourneau J, Liang M, Choufani S, Weksberg R, Wilson MD, Sedlacek Z, Gagnon C, Musova Z, Chitayat D, Shannon P, Mathieu J, Sermon K, Pearson CE. CpG Methylation, a Parent-of-Origin Effect for Maternal-Biased Transmission of Congenital Myotonic Dystrophy. Am J Hum Genet 2017; 100:488-505. [PMID: 28257691 PMCID: PMC5339342 DOI: 10.1016/j.ajhg.2017.01.033] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/26/2017] [Indexed: 12/13/2022] Open
Abstract
CTG repeat expansions in DMPK cause myotonic dystrophy (DM1) with a continuum of severity and ages of onset. Congenital DM1 (CDM1), the most severe form, presents distinct clinical features, large expansions, and almost exclusive maternal transmission. The correlation between CDM1 and expansion size is not absolute, suggesting contributions of other factors. We determined CpG methylation flanking the CTG repeat in 79 blood samples from 20 CDM1-affected individuals; 21, 27, and 11 individuals with DM1 but not CDM1 (henceforth non-CDM1) with maternal, paternal, and unknown inheritance; and collections of maternally and paternally derived chorionic villus samples (7 CVSs) and human embryonic stem cells (4 hESCs). All but two CDM1-affected individuals showed high levels of methylation upstream and downstream of the repeat, greater than non-CDM1 individuals (p = 7.04958 × 10−12). Most non-CDM1 individuals were devoid of methylation, where one in six showed downstream methylation. Only two non-CDM1 individuals showed upstream methylation, and these were maternally derived childhood onset, suggesting a continuum of methylation with age of onset. Only maternally derived hESCs and CVSs showed upstream methylation. In contrast, paternally derived samples (27 blood samples, 3 CVSs, and 2 hESCs) never showed upstream methylation. CTG tract length did not strictly correlate with CDM1 or methylation. Thus, methylation patterns flanking the CTG repeat are stronger indicators of CDM1 than repeat size. Spermatogonia with upstream methylation may not survive due to methylation-induced reduced expression of the adjacent SIX5, thereby protecting DM1-affected fathers from having CDM1-affected children. Thus, DMPK methylation may account for the maternal bias for CDM1 transmission, larger maternal CTG expansions, age of onset, and clinical continuum, and may serve as a diagnostic indicator.
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142
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Abstract
Most of the human genome encodes RNAs that do not code for proteins. These non-coding RNAs (ncRNAs) may affect normal gene expression and disease progression, making them a new class of targets for drug discovery. Because their mechanisms of action are often novel, developing drugs to target ncRNAs will involve equally novel challenges. However, many potential problems may already have been solved during the development of technologies to target mRNA. Here, we discuss the growing field of ncRNA - including microRNA, intronic RNA, repetitive RNA and long non-coding RNA - and assess the potential and challenges in their therapeutic exploitation.
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Affiliation(s)
- Masayuki Matsui
- Departments of Pharmacology and Biochemistry, UT Southwestern, Dallas, Texas 75390-9041, USA
| | - David R Corey
- Departments of Pharmacology and Biochemistry, UT Southwestern, Dallas, Texas 75390-9041, USA
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143
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Ueki J, Nakamori M, Nakamura M, Nishikawa M, Yoshida Y, Tanaka A, Morizane A, Kamon M, Araki T, Takahashi MP, Watanabe A, Inagaki N, Sakurai H. Myotonic dystrophy type 1 patient-derived iPSCs for the investigation of CTG repeat instability. Sci Rep 2017; 7:42522. [PMID: 28211918 PMCID: PMC5304155 DOI: 10.1038/srep42522] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/09/2017] [Indexed: 02/08/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal-dominant multi-system disease caused by expanded CTG repeats in dystrophia myotonica protein kinase (DMPK). The expanded CTG repeats are unstable and can increase the length of the gene with age, which worsens the symptoms. In order to establish a human stem cell system suitable for the investigation of repeat instability, DM1 patient-derived iPSCs were generated and differentiated into three cell types commonly affected in DM1, namely cardiomyocytes, neurons and myocytes. Then we precisely analysed the CTG repeat lengths in these cells. Our DM1-iPSCs showed a gradual lengthening of CTG repeats with unchanged repeat distribution in all cell lines depending on the passage numbers of undifferentiated cells. However, the average CTG repeat length did not change significantly after differentiation into different somatic cell types. We also evaluated the chromatin accessibility in DM1-iPSCs using ATAC-seq. The chromatin status in DM1 cardiomyocytes was closed at the DMPK locus as well as at SIX5 and its promoter region, whereas it was open in control, suggesting that the epigenetic modifications may be related to the CTG repeat expansion in DM1. These findings may help clarify the role of repeat instability in the CTG repeat expansion in DM1.
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Affiliation(s)
- Junko Ueki
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.,Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masayuki Nakamori
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Masahiro Nakamura
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Misato Nishikawa
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yoshinori Yoshida
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Azusa Tanaka
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Asuka Morizane
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Masayoshi Kamon
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Toshiyuki Araki
- Department of Peripheral Nervous System Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8502, Japan
| | - Masanori P Takahashi
- Department of Neurology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akira Watanabe
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hidetoshi Sakurai
- Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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144
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Embryological Results of Couples Undergoing ICSI-ET Treatments with Males Carrying the Single Nucleotide Polymorphism rs175080 of the MLH3 Gene. Int J Mol Sci 2017; 18:ijms18020314. [PMID: 28157160 PMCID: PMC5343850 DOI: 10.3390/ijms18020314] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 01/26/2017] [Indexed: 01/06/2023] Open
Abstract
Human MLH3 (hMLH3) gene has been suggested to play a role in the DNA mismatch repair mechanism, while it may also be associated with abnormal spermatogenesis and subsequently male infertility. The aim of the present study was to investigate possible relationships between the single nucleotide polymorphism (SNP) rs175080 in the MLH3 gene of males and the embryological results in couples undergoing intracytoplasmatic sperm injection-embryo transfer (ICSI-ET) treatments. A total of 132 men volunteered for the study and gave written informed consent. All couples were subjected to ICSI-ET treatments in the years 2010 to 2012. The couples were divided into three groups according to the genotype of their husbands: the wild type GG (n = 28), the heterozygotic type GA (n = 72) and the mutant type AA (n = 32). Significantly lower sperm concentration and progressive motility were observed in the AA group as compared to the other two groups (Concentration: 14.57 ± 4.9 mil/mL in AA, 38.3 ± 5.4 mil/mL in GA and 41.03 ± 6.8 mil/mL in GG, p < 0.05, mean ± standard error of the mean—SEM). However, significantly better embryological results (mean score of embryo quality–MSEQ) were found in the AA (8.12 ± 0.5) and the GA group (7.36 ± 0.4) as compared to the GG group (5.82 ± 0.7), (p < 0.05). Clinical pregnancy rate was significantly higher in the AA genotype group (43.8%) and the GA group (30.6%) than in the GG group (14.3%), (p < 0.05). Live birth rate was not different. It is suggested for the first time that the deteriorating effect of the mutant type on sperm characteristics does not impact on embryo development after fertilization in vitro.
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145
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Effects of Replication and Transcription on DNA Structure-Related Genetic Instability. Genes (Basel) 2017; 8:genes8010017. [PMID: 28067787 PMCID: PMC5295012 DOI: 10.3390/genes8010017] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 12/21/2016] [Accepted: 12/26/2016] [Indexed: 12/20/2022] Open
Abstract
Many repetitive sequences in the human genome can adopt conformations that differ from the canonical B-DNA double helix (i.e., non-B DNA), and can impact important biological processes such as DNA replication, transcription, recombination, telomere maintenance, viral integration, transposome activation, DNA damage and repair. Thus, non-B DNA-forming sequences have been implicated in genetic instability and disease development. In this article, we discuss the interactions of non-B DNA with the replication and/or transcription machinery, particularly in disease states (e.g., tumors) that can lead to an abnormal cellular environment, and how such interactions may alter DNA replication and transcription, leading to potential conflicts at non-B DNA regions, and eventually result in genetic stability and human disease.
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146
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Jones L, Houlden H, Tabrizi SJ. DNA repair in the trinucleotide repeat disorders. Lancet Neurol 2017; 16:88-96. [PMID: 27979358 DOI: 10.1016/s1474-4422(16)30350-7] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/22/2016] [Accepted: 10/27/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Inherited diseases caused by unstable repeated DNA sequences are rare, but together represent a substantial cause of morbidity. Trinucleotide repeat disorders are severe, usually life-shortening, neurological disorders caused by nucleotide expansions, and most have no disease-modifying treatments. Longer repeat expansions are associated with genetic anticipation (ie, earlier disease onset in successive generations), although the differences in age at onset are not entirely accounted for by repeat length. Such phenotypic variation within disorders implies the existence of additional modifying factors in pathways that can potentially be modulated to treat disease. RECENT DEVELOPMENTS A genome-wide association study detected genetic modifiers of age at onset in Huntington's disease. Similar findings were seen in the spinocerebellar ataxias, indicating an association between DNA damage-response and repair pathways and the age at onset of disease. These studies also suggest that a common genetic mechanism modulates age at onset across polyglutamine diseases and could extend to other repeat expansion disorders. Genetic defects in DNA repair underlie other neurodegenerative disorders (eg, ataxia-telangiectasia), and DNA double-strand breaks are crucial to the modulation of early gene expression, which provides a mechanistic link between DNA repair and neurodegeneration. Mismatch and base-excision repair are important in the somatic expansion of repeated sequences in mouse models of trinucleotide repeat disorders, and somatic expansion of the expanded CAG tract in HTT correlates with age at onset of Huntington's disease and other trinucleotide repeat disorders. WHERE NEXT?: To understand the common genetic architecture of trinucleotide repeat disorders and any further genetic susceptibilities in individual disorders, genetic analysis with increased numbers of variants and sample sizes is needed, followed by sequencing approaches to define the phenotype-modifying variants. The findings must then be translated into cell biology analyses to elucidate the mechanisms through which the genetic variants operate. Genes that have roles in the DNA damage response could underpin a common DNA repeat-based mechanism and provide new therapeutic targets (and hence therapeutics) in multiple trinucleotide repeat disorders.
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Affiliation(s)
- Lesley Jones
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, UK.
| | - Henry Houlden
- Department of Molecular Neuroscience and MRC Centre for Neuromuscular Diseases, Institute of Neurology, Queen Square, London, UK
| | - Sarah J Tabrizi
- UCL Huntington's Disease Centre, Department of Neurodegenerative Disease, Institute of Neurology, University College London, London, UK
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147
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Eid R, Arab NTT, Greenwood MT. Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1864:399-430. [PMID: 27939167 DOI: 10.1016/j.bbamcr.2016.12.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/08/2016] [Accepted: 12/04/2016] [Indexed: 12/11/2022]
Abstract
Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe2+) and ferric (Fe3+) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.
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Affiliation(s)
- Rawan Eid
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Nagla T T Arab
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada
| | - Michael T Greenwood
- Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, Canada.
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148
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The role of break-induced replication in large-scale expansions of (CAG) n/(CTG) n repeats. Nat Struct Mol Biol 2016; 24:55-60. [PMID: 27918542 PMCID: PMC5215974 DOI: 10.1038/nsmb.3334] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/31/2016] [Indexed: 12/11/2022]
Abstract
Expansions of (CAG)n•(CTG)n trinucleotide repeats are responsible for over a dozen neuromuscular and neurodegenerative disorders. Large-scale expansions are typical for human pedigrees and may be explained by iterative small-scale events such as strand slippage during replication or repair DNA synthesis. Alternatively, a distinct mechanism could lead to a large-scale repeat expansion at a step. To distinguish between these possibilities, we developed a novel experimental system specifically tuned to analyze large-scale expansions of (CAG)n•(CTG)n repeats in Saccharomyces cerevisiae. The median size of repeat expansions was ~60 triplets, though additions in excess of 150 triplets were also observed. Genetic analysis revealed that Rad51, Rad52, Mre11, Pol32, Pif1, and Mus81 and/or Yen1 proteins are required for large-scale expansions, whereas proteins previously implicated in small-scale expansions are not involved. Based on these results, we propose a new model for large-scale expansions based on recovery of replication forks broken at (CAG)n•(CTG)n repeats via break-induced replication.
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149
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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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150
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Chakraborty U, Alani E. Understanding how mismatch repair proteins participate in the repair/anti-recombination decision. FEMS Yeast Res 2016; 16:fow071. [PMID: 27573382 PMCID: PMC5976031 DOI: 10.1093/femsyr/fow071] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/24/2016] [Accepted: 08/24/2016] [Indexed: 01/06/2023] Open
Abstract
Mismatch repair (MMR) systems correct DNA mismatches that result from DNA polymerase misincorporation errors. Mismatches also appear in heteroduplex DNA intermediates formed during recombination between nearly identical sequences, and can be corrected by MMR or removed through an unwinding mechanism, known as anti-recombination or heteroduplex rejection. We review studies, primarily in baker's yeast, which support how specific factors can regulate the MMR/anti-recombination decision. Based on recent advances, we present models for how DNA structure, relative amounts of key repair proteins, the timely localization of repair proteins to DNA substrates and epigenetic marks can modulate this critical decision.
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Affiliation(s)
- Ujani Chakraborty
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2703, USA
| | - Eric Alani
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2703, USA
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