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Baqai N, Amin R, Fatima T, Ahmed Z, Faiz N. Expression Profiling of EMT Transcriptional Regulators ZEB1 and ZEB2 in Different Histopathological Grades of Oral Squamous Cell Carcinoma Patients. Curr Genomics 2024; 25:140-151. [PMID: 38751602 PMCID: PMC11092914 DOI: 10.2174/0113892029284920240212091903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 05/18/2024] Open
Abstract
Background Pakistan has a high burden of oral cancers, with a prevalence rate of around 9%. Oral Squamous Cell Carcinoma (OSCC) accounts for about 90% of oral cancer cases. Epithelial to Mesenchymal Transition (EMT) gets highly stimulated in tumor cells by adopting subsequent malignant features of highly invasive cancer populations. Zinc Finger E-Box binding factors, ZEB1 and ZEB2, are regulatory proteins that promote EMT by suppressing the adherent ability of cells transforming into highly motile cancerous cells. The present study aimed to analyze the expression of EMT regulators, ZEB1 and ZEB2, and their association with the clinicopathological features in different grades of OSCC patients. Methods Tissue samples were collected for both case and control groups from the recruited study participants. Cancer tissues (cases) were collected from the confirmed OSCC patients, and healthy tissues (controls) were collected from third-molar dental extraction patients. The study participants were recruited with informed consent and brief demographic and clinical characteristics. The case group was further segregated with respect to the histological cancer grading system into well-differentiated (WD), moderately differentiated (MD), and poorly differentiated (PD) squamous cell carcinoma (SCC) groups. RNA was extracted from the tissue samples for expression profiling of ZEB1 and ZEB2 genes through quantitative real-time PCR (qRT-PCR). Results All of the recruited participants had a mean age of 46.55 ± 11.7 (years), with most of them belonging to Urdu speaking ethnic group and were married. The BMI (kg/m2) of the healthy participants was in the normal range (18-22 kg/m2). However, BMI was found to be reduced with the proliferation in the pathological state of cancer. The oral hygiene of patients was better than the healthy participants, possibly due to the strict oral hygiene practice concerns of consultants. Every recruited OSCC patient had one or multiple addiction habits for more than a year. Patients reported health frailty (46.6%), unhealed mouth sores (40%), swallowing difficulties and white/reddish marks (80%), and restricted mouth opening (64.4%). Furthermore, 82.2% of the recruited patients observed symptoms within 1-12 months, and buccal mucosa was the most exposed tumor site among 55.6% of the patients. Expression profiling of EMT regulators showed gradual over-expressions of ZEB1 (8, 20, and 42 folds) and ZEB2 (4, 10, and 18 folds) in respective histological cancer grades. Conclusion High expressions of ZEBs have been significantly associated with cancer progression and poor health. However, no association was found between OSCC with other clinicopathological features when compared to healthy controls.
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Affiliation(s)
- Neha Baqai
- Dow Research Institute of Biotechnology and Biomedical Sciences, Dow University of Health Sciences, Ojha Campus, Karachi, Pakistan
| | - Rafat Amin
- Dow College of Biotechnology, Dow University of Health Sciences, Ojha Campus, Karachi, Pakistan
| | - Tehseen Fatima
- Dow College of Biotechnology, Dow University of Health Sciences, Ojha Campus, Karachi, Pakistan
| | - Zeba Ahmed
- Otolaryngology, Dow Medical College-Dr.Ruth KM Pfau Civil Hospital Karachi, Dow University of Health Sciences, Karachi, Pakistan
| | - Nousheen Faiz
- Institute of Basic Medical Sciences, Dow University of Health Sciences, Ojha Campus, Karachi, Pakistan
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2
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Pressl C, Mätlik K, Kus L, Darnell P, Luo JD, Paul MR, Weiss AR, Liguore W, Carroll TS, Davis DA, McBride J, Heintz N. Selective vulnerability of layer 5a corticostriatal neurons in Huntington's disease. Neuron 2024; 112:924-941.e10. [PMID: 38237588 DOI: 10.1016/j.neuron.2023.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/18/2023] [Accepted: 12/13/2023] [Indexed: 01/30/2024]
Abstract
The properties of the cell types that are selectively vulnerable in Huntington's disease (HD) cortex, the nature of somatic CAG expansions of mHTT in these cells, and their importance in CNS circuitry have not been delineated. Here, we employed serial fluorescence-activated nuclear sorting (sFANS), deep molecular profiling, and single-nucleus RNA sequencing (snRNA-seq) of motor-cortex samples from thirteen predominantly early stage, clinically diagnosed HD donors and selected samples from cingulate, visual, insular, and prefrontal cortices to demonstrate loss of layer 5a pyramidal neurons in HD. Extensive mHTT CAG expansions occur in vulnerable layer 5a pyramidal cells, and in Betz cells, layers 6a and 6b neurons that are resilient in HD. Retrograde tracing experiments in macaque brains identify layer 5a neurons as corticostriatal pyramidal cells. We propose that enhanced somatic mHTT CAG expansion and altered synaptic function act together to cause corticostriatal disconnection and selective neuronal vulnerability in HD cerebral cortex.
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Affiliation(s)
- Christina Pressl
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Kert Mätlik
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Laura Kus
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Paul Darnell
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA
| | - Ji-Dung Luo
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - Matthew R Paul
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - Alison R Weiss
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA
| | - William Liguore
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA
| | - Thomas S Carroll
- Bioinformatics Resource Center, The Rockefeller University, New York, NY, USA
| | - David A Davis
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jodi McBride
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA
| | - Nathaniel Heintz
- Laboratory of Molecular Biology, The Rockefeller University, New York, NY, USA.
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3
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Abstract
At fifteen different genomic locations, the expansion of a CAG/CTG repeat causes a neurodegenerative or neuromuscular disease, the most common being Huntington's disease and myotonic dystrophy type 1. These disorders are characterized by germline and somatic instability of the causative CAG/CTG repeat mutations. Repeat lengthening, or expansion, in the germline leads to an earlier age of onset or more severe symptoms in the next generation. In somatic cells, repeat expansion is thought to precipitate the rate of disease. The mechanisms underlying repeat instability are not well understood. Here we review the mammalian model systems that have been used to study CAG/CTG repeat instability, and the modifiers identified in these systems. Mouse models have demonstrated prominent roles for proteins in the mismatch repair pathway as critical drivers of CAG/CTG instability, which is also suggested by recent genome-wide association studies in humans. We draw attention to a network of connections between modifiers identified across several systems that might indicate pathway crosstalk in the context of repeat instability, and which could provide hypotheses for further validation or discovery. Overall, the data indicate that repeat dynamics might be modulated by altering the levels of DNA metabolic proteins, their regulation, their interaction with chromatin, or by direct perturbation of the repeat tract. Applying novel methodologies and technologies to this exciting area of research will be needed to gain deeper mechanistic insight that can be harnessed for therapies aimed at preventing repeat expansion or promoting repeat contraction.
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Affiliation(s)
- Vanessa C. Wheeler
- Molecular Neurogenetics Unit, Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA,Department of Neurology, Harvard Medical School, Boston, MA, USA,Correspondence to: Vanessa C. Wheeler, Center for Genomic Medicine, Massachusetts Hospital, Boston MAA 02115, USA. E-mail: . and Vincent Dion, UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK. E-mail:
| | - Vincent Dion
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, UK,Correspondence to: Vanessa C. Wheeler, Center for Genomic Medicine, Massachusetts Hospital, Boston MAA 02115, USA. E-mail: . and Vincent Dion, UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ Cardiff, UK. E-mail:
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4
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Yang B, Borgeaud AC, Buřičová M, Aeschbach L, Rodríguez-Lima O, Ruiz Buendía GA, Cinesi C, Taylor AS, Baubec T, Dion V. Expanded CAG/CTG repeats resist gene silencing mediated by targeted Epigenome editing. Hum Mol Genet 2021; 31:386-398. [PMID: 34494094 PMCID: PMC8825355 DOI: 10.1093/hmg/ddab255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 05/08/2021] [Accepted: 08/25/2021] [Indexed: 11/14/2022] Open
Abstract
Expanded CAG/CTG repeat disorders affect over 1 in 2500 individuals worldwide. Potential therapeutic avenues include gene silencing and modulation of repeat instability. However, there are major mechanistic gaps in our understanding of these processes, which prevent the rational design of an efficient treatment. To address this, we developed a novel system, ParB/ANCHOR-mediated Inducible Targeting (PInT), in which any protein can be recruited at will to a GFP reporter containing an expanded CAG/CTG repeat. Previous studies have implicated the histone deacetylase HDAC5 and the DNA methyltransferase DNMT1 as modulators of repeat instability via mechanisms that are not fully understood. Using PInT, we found no evidence that HDAC5 or DNMT1 modulate repeat instability upon targeting to the expanded repeat, suggesting that their effect is independent of local chromatin structure. Unexpectedly, we found that expanded CAG/CTG repeats reduce the effectiveness of gene silencing mediated by targeting HDAC5 and DNMT1. The repeat-length effect in gene silencing by HDAC5 was abolished by a small molecule inhibitor of HDAC3. Our results have important implications on the design of epigenome editing approaches for expanded CAG/CTG repeat disorders. PInT is a versatile synthetic system to study the effect of any sequence of interest on epigenome editing.
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Affiliation(s)
- Bin Yang
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Alicia C Borgeaud
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland.,UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
| | - Marcela Buřičová
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
| | - Lorène Aeschbach
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Oscar Rodríguez-Lima
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Gustavo A Ruiz Buendía
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Cinzia Cinesi
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015, Lausanne, Switzerland
| | - Alysha S Taylor
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
| | - Tuncay Baubec
- Department of Molecular Mechanisms of Disease, University of Zurich, 8057, Zurich, Switzerland
| | - Vincent Dion
- UK Dementia Research Institute at Cardiff University, Hadyn Ellis Building, Maindy Road, CF24 4HQ, Cardiff, United Kingdom
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5
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Richard GF. The Startling Role of Mismatch Repair in Trinucleotide Repeat Expansions. Cells 2021; 10:cells10051019. [PMID: 33925919 PMCID: PMC8145212 DOI: 10.3390/cells10051019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/26/2022] Open
Abstract
Trinucleotide repeats are a peculiar class of microsatellites whose expansions are responsible for approximately 30 human neurological or developmental disorders. The molecular mechanisms responsible for these expansions in humans are not totally understood, but experiments in model systems such as yeast, transgenic mice, and human cells have brought evidence that the mismatch repair machinery is involved in generating these expansions. The present review summarizes, in the first part, the role of mismatch repair in detecting and fixing the DNA strand slippage occurring during microsatellite replication. In the second part, key molecular differences between normal microsatellites and those that show a bias toward expansions are extensively presented. The effect of mismatch repair mutants on microsatellite expansions is detailed in model systems, and in vitro experiments on mismatched DNA substrates are described. Finally, a model presenting the possible roles of the mismatch repair machinery in microsatellite expansions is proposed.
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Affiliation(s)
- Guy-Franck Richard
- Institut Pasteur, CNRS UMR3525, 25 rue du Docteur Roux, 75015 Paris, France
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6
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Alternative DNA Structures In Vivo: Molecular Evidence and Remaining Questions. Microbiol Mol Biol Rev 2020; 85:85/1/e00110-20. [PMID: 33361270 DOI: 10.1128/mmbr.00110-20] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Duplex DNA naturally folds into a right-handed double helix in physiological conditions. Some sequences of unusual base composition may nevertheless form alternative structures, as was shown for many repeated sequences in vitro However, evidence for the formation of noncanonical structures in living cells is difficult to gather. It mainly relies on genetic assays demonstrating their function in vivo or through genetic instability reflecting particular properties of such structures. Efforts were made to reveal their existence directly in a living cell, mainly by generating antibodies specific to secondary structures or using chemical ligands selected for their affinity to these structures. Among secondary structure-forming DNAs are G-quadruplexes, human fragile sites containing minisatellites, AT-rich regions, inverted repeats able to form cruciform structures, hairpin-forming CAG/CTG triplet repeats, and triple helices formed by homopurine-homopyrimidine GAA/TTC trinucleotide repeats. Many of these alternative structures are involved in human pathologies, such as neurological or developmental disorders, as in the case of trinucleotide repeats, or cancers triggered by translocations linked to fragile sites. This review will discuss and highlight evidence supporting the formation of alternative DNA structures in vivo and will emphasize the role of the mismatch repair machinery in binding mispaired DNA duplexes, triggering genetic instability.
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7
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Franck S, Barbé L, Ardui S, De Vlaeminck Y, Allemeersch J, Dziedzicka D, Spits C, Vanroye F, Hilven P, Duqué G, Vermeesch JR, Gheldof A, Sermon K. MSH2 knock-down shows CTG repeat stability and concomitant upstream demethylation at the DMPK locus in myotonic dystrophy type 1 human embryonic stem cells. Hum Mol Genet 2020; 29:3566-3577. [PMID: 33242073 DOI: 10.1093/hmg/ddaa250] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/20/2020] [Accepted: 11/20/2020] [Indexed: 12/14/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is caused by expansion of a CTG repeat in the DMPK gene, where expansion size and somatic mosaicism correlates with disease severity and age of onset. While it is known that the mismatch repair protein MSH2 contributes to the unstable nature of the repeat, its role on other disease-related features, such as CpG methylation upstream of the repeat, is unknown. In this study, we investigated the effect of an MSH2 knock-down (MSH2KD) on both CTG repeat dynamics and CpG methylation pattern in human embryonic stem cells (hESC) carrying the DM1 mutation. Repeat size in MSH2 wild-type (MSH2WT) and MSH2KD DM1 hESC was determined by PacBio sequencing and CpG methylation by bisulfite massive parallel sequencing. We found stabilization of the CTG repeat concurrent with a gradual loss of methylation upstream of the repeat in MSH2KD cells, while the repeat continued to expand and upstream methylation remained unchanged in MSH2WT control lines. Repeat instability was re-established and biased towards expansions upon MSH2 transgenic re-expression in MSH2KD lines while upstream methylation was not consistently re-established. We hypothesize that the hypermethylation at the mutant DM1 locus is promoted by the MMR machinery and sustained by a constant DNA repair response, establishing a potential mechanistic link between CTG repeat instability and upstream CpG methylation. Our work represents a first step towards understanding how epigenetic alterations and repair pathways connect and contribute to the DM1 pathology.
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Affiliation(s)
- Silvie Franck
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Lise Barbé
- Center for systems and Therapeutics, Gladstone Institutes, Finkbeiner lab, San Francisco, CA 94158, USA
| | - Simon Ardui
- Center of Human Genetics, University Hospital Leuven, KU Leuven, Laboratory for Cytogenetics and Genome Research, Leuven 3000, Belgium
| | - Yannick De Vlaeminck
- Laboratory for Molecular and Cellular Therapy, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | | | - Dominika Dziedzicka
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Claudia Spits
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Fien Vanroye
- Laboratory HIV/STD, Institute of Tropical Medicine Antwerp, Antwerp 2000, Belgium
| | - Pierre Hilven
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Geoffrey Duqué
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
| | - Joris R Vermeesch
- Center of Human Genetics, University Hospital Leuven, KU Leuven, Laboratory for Cytogenetics and Genome Research, Leuven 3000, Belgium
| | - Alexander Gheldof
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium.,Center of Medical Genetics, UZ Brussel, Brussels 1090, Belgium
| | - Karen Sermon
- Department Reproduction and Genetics, Vrije Universiteit Brussel, Brussels 1090, Belgium
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8
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Tabrizi SJ, Flower MD, Ross CA, Wild EJ. Huntington disease: new insights into molecular pathogenesis and therapeutic opportunities. Nat Rev Neurol 2020; 16:529-546. [PMID: 32796930 DOI: 10.1038/s41582-020-0389-4] [Citation(s) in RCA: 216] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2020] [Indexed: 12/11/2022]
Abstract
Huntington disease (HD) is a neurodegenerative disease caused by CAG repeat expansion in the huntingtin gene (HTT) and involves a complex web of pathogenic mechanisms. Mutant HTT (mHTT) disrupts transcription, interferes with immune and mitochondrial function, and is aberrantly modified post-translationally. Evidence suggests that the mHTT RNA is toxic, and at the DNA level, somatic CAG repeat expansion in vulnerable cells influences the disease course. Genome-wide association studies have identified DNA repair pathways as modifiers of somatic instability and disease course in HD and other repeat expansion diseases. In animal models of HD, nucleocytoplasmic transport is disrupted and its restoration is neuroprotective. Novel cerebrospinal fluid (CSF) and plasma biomarkers are among the earliest detectable changes in individuals with premanifest HD and have the sensitivity to detect therapeutic benefit. Therapeutically, the first human trial of an HTT-lowering antisense oligonucleotide successfully, and safely, reduced the CSF concentration of mHTT in individuals with HD. A larger trial, powered to detect clinical efficacy, is underway, along with trials of other HTT-lowering approaches. In this Review, we discuss new insights into the molecular pathogenesis of HD and future therapeutic strategies, including the modulation of DNA repair and targeting the DNA mutation itself.
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Affiliation(s)
- Sarah J Tabrizi
- Huntington's Disease Centre, University College London, London, UK. .,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, London, UK. .,UK Dementia Research Institute, University College London, London, UK.
| | - Michael D Flower
- Huntington's Disease Centre, University College London, London, UK.,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
| | - Christopher A Ross
- Departments of Neurology, Neuroscience and Pharmacology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Edward J Wild
- Huntington's Disease Centre, University College London, London, UK.,Department of Neurodegenerative Disease, Queen Square Institute of Neurology, University College London, London, UK
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9
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Zheng J, Xu H, Cao H. A Long Polymorphic GT Microsatellite within a Gene Promoter Mediates Non-Imprinted Allele-Specific DNA Methylation of a CpG Island in a Goldfish Inter-Strain Hybrid. Int J Mol Sci 2019; 20:ijms20163923. [PMID: 31409051 PMCID: PMC6721770 DOI: 10.3390/ijms20163923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/01/2019] [Accepted: 08/06/2019] [Indexed: 11/26/2022] Open
Abstract
It is now widely accepted that allele-specific DNA methylation (ASM) commonly occurs at non-imprinted loci. Most of the non-imprinted ASM regions observed both within and outside of the CpG island show a strong correlation with DNA polymorphisms. However, what polymorphic cis-acting elements mediate non-imprinted ASM of the CpG island remains unclear. In this study, we investigated the impact of polymorphic GT microsatellites within the gene promoter on non-imprinted ASM of the local CpG island in goldfish. We generated various goldfish heterozygotes, in which the length of GT microsatellites or some non-repetitive sequences in the promoter of no tail alleles was different. By examining the methylation status of the downstream CpG island in these heterozygotes, we found that polymorphisms of a long GT microsatellite can lead to the ASM of the downstream CpG island during oogenesis and embryogenesis, polymorphisms of short GT microsatellites and non-repetitive sequences in the promoter exhibited no significant effect on the methylation of the CpG island. We also observed that the ASM of the CpG island was associated with allele-specific expression in heterozygous embryos. These results suggest that a long polymorphic GT microsatellite within a gene promoter mediates non-imprinted ASM of the local CpG island in a goldfish inter-strain hybrid.
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Affiliation(s)
- Jianbo Zheng
- Zhejiang Institute of Freshwater Fisheries, Huzhou 313001, China.
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
| | - Haomang Xu
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Huiwen Cao
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
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10
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Loureiro JR, Oliveira CL, Mota C, Castro AF, Costa C, Loureiro JL, Coutinho P, Martins S, Sequeiros J, Silveira I. Mutational mechanism for DAB1 (ATTTC) n insertion in SCA37: ATTTT repeat lengthening and nucleotide substitution. Hum Mutat 2019; 40:404-412. [PMID: 30588707 DOI: 10.1002/humu.23704] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 11/28/2018] [Accepted: 12/22/2018] [Indexed: 12/20/2022]
Abstract
Dynamic mutations by microsatellite instability are the molecular basis of a growing number of neuromuscular and neurodegenerative diseases. Repetitive stretches in the human genome may drive pathogenicity, either by expansion above a given threshold, or by insertion of abnormal tracts in nonpathogenic polymorphic repetitive regions, as is the case in spinocerebellar ataxia type 37 (SCA37). We have recently established that this neurodegenerative disease is caused by an (ATTTC)n insertion within an (ATTTT)n in a noncoding region of DAB1. We now investigated the mutational mechanism that originated the (ATTTC)n insertion within an ancestral (ATTTT)n . Approximately 3% of nonpathogenic (ATTTT)n alleles are interspersed by AT-rich motifs, contrarily to mutant alleles that are composed of pure (ATTTT)n and (ATTTC)n stretches. Haplotype studies in unaffected chromosomes suggested that the primary mutational mechanism, leading to the (ATTTC)n insertion, was likely one or more T>C substitutions in an (ATTTT)n pure allele of approximately 200 repeats. Then, the (ATTTC)n expanded in size, originating a deleterious allele in DAB1 that leads to SCA37. This is likely the mutational mechanism in three similar (TTTCA)n insertions responsible for familial myoclonic epilepsy. Because (ATTTT)n tracts are frequent in the human genome, many loci could be at risk for this mutational process.
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Affiliation(s)
- Joana R Loureiro
- Genetics of Cognitive Dysfunction Laboratory, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal.,ICBAS, Universidade do Porto, Porto, Portugal
| | - Cláudia L Oliveira
- Genetics of Cognitive Dysfunction Laboratory, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal
| | - Carolina Mota
- Genetics of Cognitive Dysfunction Laboratory, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal
| | - Ana F Castro
- Genetics of Cognitive Dysfunction Laboratory, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal
| | - Cristina Costa
- Department of Neurology, Hospital Prof. Doutor Fernando Fonseca, Amadora, Portugal
| | - José L Loureiro
- IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal.,UnIGENe, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Department of Neurology, Hospital São Sebastião, Feira, Portugal
| | - Paula Coutinho
- IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal.,UnIGENe, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Sandra Martins
- Population Genetics & Evolution, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Institute of Molecular Pathology and Immunology, University of Porto, Porto, Portugal
| | - Jorge Sequeiros
- IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal.,ICBAS, Universidade do Porto, Porto, Portugal.,UnIGENe, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Isabel Silveira
- Genetics of Cognitive Dysfunction Laboratory, i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC- Institute for Molecular and Cell Biology, Universidade do Porto, Porto, Portugal
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11
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The G-rich Repeats in FMR1 and C9orf72 Loci Are Hotspots for Local Unpairing of DNA. Genetics 2018; 210:1239-1252. [PMID: 30396881 DOI: 10.1534/genetics.118.301672] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 10/15/2018] [Indexed: 12/13/2022] Open
Abstract
Pathological mutations involving noncoding microsatellite repeats are typically located near promoters in CpG islands and are coupled with extensive repeat instability when sufficiently long. What causes these regions to be prone to repeat instability is not fully understood. There is a general consensus that instability results from the induction of unusual structures in the DNA by the repeats as a consequence of mispairing between complementary strands. In addition, there is some evidence that repeat instability is mediated by RNA transcription through the formation of three-stranded nucleic structures composed of persistent DNA:RNA hybrids, concomitant with single-strand DNA displacements (R-loops). Using human embryonic stem cells with wild-type and repeat expanded alleles in the FMR1 (CGGs) and C9orf72 (GGGGCCs) genes, we show that these loci constitute preferential sites (hotspots) for DNA unpairing. When R-loops are formed, DNA unpairing is more extensive, and is coupled with the interruptions of double-strand structures by the nontranscribing (G-rich) DNA strand. These interruptions are likely to reflect unusual structures in the DNA that drive repeat instability when the G-rich repeats considerably expand. Further, we demonstrate that when the CGGs in FMR1 are hyper-methylated and transcriptionally inactive, local DNA unpairing is abolished. Our study thus takes one more step toward the identification of dynamic, unconventional DNA structures across the G-rich repeats at FMR1 and C9orf72 disease-associated loci.
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12
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Trinucleotide repeat instability during double-strand break repair: from mechanisms to gene therapy. Curr Genet 2018; 65:17-28. [DOI: 10.1007/s00294-018-0865-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/25/2018] [Accepted: 07/01/2018] [Indexed: 12/26/2022]
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13
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TALEN-Induced Double-Strand Break Repair of CTG Trinucleotide Repeats. Cell Rep 2018; 22:2146-2159. [DOI: 10.1016/j.celrep.2018.01.083] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 12/19/2017] [Accepted: 01/25/2018] [Indexed: 11/19/2022] Open
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14
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Keogh N, Chan KY, Li GM, Lahue RS. MutSβ abundance and Msh3 ATP hydrolysis activity are important drivers of CTG•CAG repeat expansions. Nucleic Acids Res 2017; 45:10068-10078. [PMID: 28973443 PMCID: PMC5622409 DOI: 10.1093/nar/gkx650] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 07/14/2017] [Indexed: 01/01/2023] Open
Abstract
CTG•CAG repeat expansions cause at least twelve inherited neurological diseases. Expansions require the presence, not the absence, of the mismatch repair protein MutSβ (Msh2-Msh3 heterodimer). To evaluate properties of MutSβ that drive expansions, previous studies have tested under-expression, ATPase function or polymorphic variants of Msh2 and Msh3, but in disparate experimental systems. Additionally, some variants destabilize MutSβ, potentially masking the effects of biochemical alterations of the variations. Here, human Msh3 was mutated to selectively inactivate MutSβ. Msh3-/- cells are severely defective for CTG•CAG repeat expansions but show full activity on contractions. Msh3-/- cells provide a single, isogenic system to add back Msh3 and test key biochemical features of MutSβ on expansions. Msh3 overexpression led to high expansion activity and elevated levels of MutSβ complex, indicating that MutSβ abundance drives expansions. An ATPase-defective Msh3 expressed at normal levels was as defective in expansions as Msh3-/- cells, indicating that Msh3 ATPase function is critical for expansions. Expression of two Msh3 polymorphic variants at normal levels showed no detectable change in expansions, suggesting these polymorphisms primarily affect Msh3 protein stability, not activity. In summary, CTG•CAG expansions are limited by the abundance of MutSβ and rely heavily on Msh3 ATPase function.
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Affiliation(s)
- Norma Keogh
- Centre for Chromosome Biology, National University of Ireland Galway, Newcastle Road, Galway H91T K33, Ireland
| | - Kara Y Chan
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Guo-Min Li
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY 40536, USA.,Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, CA 90033, USA
| | - Robert S Lahue
- Centre for Chromosome Biology, National University of Ireland Galway, Newcastle Road, Galway H91T K33, Ireland.,NCBES Galway Neuroscience Centre, National University of Ireland Galway, Newcastle Road, Galway H91T K33, Ireland
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15
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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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16
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Polyzos AA, McMurray CT. Close encounters: Moving along bumps, breaks, and bubbles on expanded trinucleotide tracts. DNA Repair (Amst) 2017; 56:144-155. [PMID: 28690053 PMCID: PMC5558859 DOI: 10.1016/j.dnarep.2017.06.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Expansion of simple triplet repeats (TNR) underlies more than 30 severe degenerative diseases. There is a good understanding of the major pathways generating an expansion, and the associated polymerases that operate during gap filling synthesis at these "difficult to copy" sequences. However, the mechanism by which a TNR is repaired depends on the type of lesion, the structural features imposed by the lesion, the assembled replication/repair complex, and the polymerase that encounters it. The relationships among these parameters are exceptionally complex and how they direct pathway choice is poorly understood. In this review, we consider the properties of polymerases, and how encounters with GC-rich or abnormal structures might influence polymerase choice and the success of replication and repair. Insights over the last three years have highlighted new mechanisms that provide interesting choices to consider in protecting genome stability.
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Affiliation(s)
- Aris A Polyzos
- MBIB Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, United States
| | - Cynthia T McMurray
- MBIB Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, United States.
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17
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Genetic Contributors to Intergenerational CAG Repeat Instability in Huntington's Disease Knock-In Mice. Genetics 2016; 205:503-516. [PMID: 27913616 PMCID: PMC5289832 DOI: 10.1534/genetics.116.195578] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/12/2016] [Indexed: 12/11/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by the expansion of a CAG trinucleotide repeat in exon 1 of the HTT gene. Longer repeat sizes are associated with increased disease penetrance and earlier ages of onset. Intergenerationally unstable transmissions are common in HD families, partly underlying the genetic anticipation seen in this disorder. HD CAG knock-in mouse models also exhibit a propensity for intergenerational repeat size changes. In this work, we examine intergenerational instability of the CAG repeat in over 20,000 transmissions in the largest HD knock-in mouse model breeding datasets reported to date. We confirmed previous observations that parental sex drives the relative ratio of expansions and contractions. The large datasets further allowed us to distinguish effects of paternal CAG repeat length on the magnitude and frequency of expansions and contractions, as well as the identification of large repeat size jumps in the knock-in models. Distinct degrees of intergenerational instability were observed between knock-in mice of six background strains, indicating the occurrence of trans-acting genetic modifiers. We also found that lines harboring a neomycin resistance cassette upstream of Htt showed reduced expansion frequency, indicative of a contributing role for sequences in cis, with the expanded repeat as modifiers of intergenerational instability. These results provide a basis for further understanding of the mechanisms underlying intergenerational repeat instability.
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18
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Gadgil R, Barthelemy J, Lewis T, Leffak M. Replication stalling and DNA microsatellite instability. Biophys Chem 2016; 225:38-48. [PMID: 27914716 DOI: 10.1016/j.bpc.2016.11.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/05/2016] [Accepted: 11/05/2016] [Indexed: 01/08/2023]
Abstract
Microsatellites are short, tandemly repeated DNA motifs of 1-6 nucleotides, also termed simple sequence repeats (SRSs) or short tandem repeats (STRs). Collectively, these repeats comprise approximately 3% of the human genome Subramanian et al. (2003), Lander and Lander (2001) [1,2], and represent a large reservoir of loci highly prone to mutations Sun et al. (2012), Ellegren (2004) [3,4] that contribute to human evolution and disease. Microsatellites are known to stall and reverse replication forks in model systems Pelletier et al. (2003), Samadashwily et al. (1997), Kerrest et al. (2009) [5-7], and are hotspots of chromosomal double strand breaks (DSBs). We briefly review the relationship of these repeated sequences to replication stalling and genome instability, and present recent data on the impact of replication stress on DNA fragility at microsatellites in vivo.
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Affiliation(s)
- R Gadgil
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - J Barthelemy
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - T Lewis
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - M Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA.
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19
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Guo J, Gu L, Leffak M, Li GM. MutSβ promotes trinucleotide repeat expansion by recruiting DNA polymerase β to nascent (CAG)n or (CTG)n hairpins for error-prone DNA synthesis. Cell Res 2016; 26:775-86. [PMID: 27255792 PMCID: PMC5129881 DOI: 10.1038/cr.2016.66] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/15/2016] [Accepted: 05/17/2016] [Indexed: 12/12/2022] Open
Abstract
Expansion of (CAG)•(CTG) repeats causes a number of familial neurodegenerative disorders. Although the underlying mechanism remains largely unknown, components involved in DNA mismatch repair, particularly mismatch recognition protein MutSβ (a MSH2-MSH3 heterodimer), are implicated in (CAG)•(CTG) repeat expansion. In addition to recognizing small insertion-deletion loop-outs, MutSβ also specifically binds DNA hairpin imperfect heteroduplexes formed within (CAG)n•(CTG)n sequences. However, whether or not and how MutSβ binding triggers expansion of (CAG)•(CTG) repeats remain unknown. We show here that purified recombinant MutSβ physically interacts with DNA polymerase β (Polβ) and stimulates Polβ-catalyzed (CAG)n or (CTG)n hairpin retention. Consistent with these in vitro observations, MutSβ and Polβ interact with each other in vivo, and colocalize at (CAG)•(CTG) repeats during DNA replication. Our data support a model for error-prone processing of (CAG)n or (CTG)n hairpins by MutSβ and Polβ during DNA replication and/or repair: MutSβ recognizes (CAG)n or (CTG)n hairpins formed in the nascent DNA strand, and recruits Polβ to the complex, which then utilizes the hairpin as a primer for extension, leading to (CAG)•(CTG) repeat expansion. This study provides a novel mechanism for trinucleotide repeat expansion in both dividing and non-dividing cells.
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Affiliation(s)
- Jinzhen Guo
- Department of Basic Medical Sciences, Tsinghua University School of Medicine, Beijing 100084, China.,Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1450 Biggy Street, Los Angeles, CA 90033, USA
| | - Liya Gu
- Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1450 Biggy Street, Los Angeles, CA 90033, USA
| | - Michael Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Guo-Min Li
- Department of Basic Medical Sciences, Tsinghua University School of Medicine, Beijing 100084, China.,Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1450 Biggy Street, Los Angeles, CA 90033, USA
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20
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Viterbo D, Michoud G, Mosbach V, Dujon B, Richard GF. Replication stalling and heteroduplex formation within CAG/CTG trinucleotide repeats by mismatch repair. DNA Repair (Amst) 2016; 42:94-106. [DOI: 10.1016/j.dnarep.2016.03.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/01/2016] [Accepted: 03/11/2016] [Indexed: 10/22/2022]
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