51
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O'Hagan MP, Mergny JL, Waller ZAE. G-quadruplexes in Prague: A Bohemian Rhapsody. Biochimie 2018; 147:170-180. [PMID: 29452278 DOI: 10.1016/j.biochi.2018.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 02/07/2018] [Indexed: 12/26/2022]
Abstract
The Sixth International Meeting on Quadruplex Nucleic Acids was held at the Hotel Internationale in Prague, Czech Republic from 31 May - 3 June 2017. A vibrant interdisciplinary community of over 300 scientists gathered to share their newest results in this exciting field and exchange ideas for further investigations.
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Affiliation(s)
- Michael Paul O'Hagan
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS1 1TS, UK.
| | - Jean-Louis Mergny
- Univ. Bordeaux, ARNA Laboratory, Inserm U1212, CNRS UMR 5320, IECB, F-33600, France; Institute of Biophysics, AS CR, v.v.i., Kralovopolska 135, 612 65 Brno, Czech Republic
| | - Zoë Ann Ella Waller
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK; Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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52
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Fadista J, Lund M, Skotte L, Geller F, Nandakumar P, Chatterjee S, Matsson H, Granström AL, Wester T, Salo P, Virtanen V, Carstensen L, Bybjerg-Grauholm J, Hougaard DM, Pakarinen M, Perola M, Nordenskjöld A, Chakravarti A, Melbye M, Feenstra B. Genome-wide association study of Hirschsprung disease detects a novel low-frequency variant at the RET locus. Eur J Hum Genet 2018; 26:561-569. [PMID: 29379196 DOI: 10.1038/s41431-017-0053-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/03/2017] [Accepted: 11/07/2017] [Indexed: 12/22/2022] Open
Abstract
Hirschsprung disease (HSCR) is a congenital disorder with a population incidence of ~1/5000 live births, defined by an absence of enteric ganglia along variable lengths of the colon. HSCR genome-wide association studies (GWAS) have found common associated variants at RET, SEMA3, and NRG1, but they still fail to explain all of its heritability. To enhance gene discovery, we performed a GWAS of 170 cases identified from the Danish nationwide pathology registry with 4717 controls, based on 6.2 million variants imputed from the haplotype reference consortium panel. We found a novel low-frequency variant (rs144432435), which, when conditioning on the lead RET single-nucleotide polymorphism (SNP), was of genome-wide significance in the discovery analysis. This conditional association signal was replicated in a Swedish HSCR cohort with discovery plus replication meta-analysis conditional odds ratio of 6.6 (P = 7.7 × 10-10; 322 cases and 4893 controls). The conditional signal was, however, not replicated in two HSCR cohorts from USA and Finland, leading to the hypothesis that rs144432435 tags a rare haplotype present in Denmark and Sweden. Using the genome-wide complex trait analysis method, we estimated the SNP heritability of HSCR to be 88%, close to estimates based on classical family studies. Moreover, by using Lasso (least absolute shrinkage and selection operator) regression we were able to construct a genetic HSCR predictor with a area under the receiver operator characteristics curve of 76% in an independent validation set. In conclusion, we combined the largest collection of sporadic Hirschsprung cases to date (586 cases) to further elucidate HSCR's genetic architecture.
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Affiliation(s)
- João Fadista
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
| | - Marie Lund
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Line Skotte
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Frank Geller
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Priyanka Nandakumar
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sumantra Chatterjee
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hans Matsson
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Anna Löf Granström
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Paediatric Surgery, Astrid Lindgren Children Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Tomas Wester
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Paediatric Surgery, Astrid Lindgren Children Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Perttu Salo
- Department of Health, National Institute for Health and Welfare, Helsinki, Finland
| | - Valtter Virtanen
- Pediatric Surgery, Children's Hospital, University of Helsinki, Helsinki, Finland
| | - Lisbeth Carstensen
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
| | - Jonas Bybjerg-Grauholm
- Department of Congenital Disorders, Danish Centre for Neonatal Screening, Statens Serum Institut, Copenhagen, Denmark
| | - David Michael Hougaard
- Department of Congenital Disorders, Danish Centre for Neonatal Screening, Statens Serum Institut, Copenhagen, Denmark
| | - Mikko Pakarinen
- Pediatric Surgery, Children's Hospital, University of Helsinki, Helsinki, Finland
| | - Markus Perola
- Department of Health, National Institute for Health and Welfare, Helsinki, Finland
| | - Agneta Nordenskjöld
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Paediatric Surgery, Astrid Lindgren Children Hospital, Karolinska University Hospital, Stockholm, Sweden.,Center of Molecular Medicine, Karolinska institutet, Stockholm, Sweden
| | - Aravinda Chakravarti
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mads Melbye
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.,Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Bjarke Feenstra
- Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark
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53
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Lebel M, Monnat RJ. Werner syndrome (WRN) gene variants and their association with altered function and age-associated diseases. Ageing Res Rev 2018; 41:82-97. [PMID: 29146545 DOI: 10.1016/j.arr.2017.11.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 11/07/2017] [Accepted: 11/09/2017] [Indexed: 01/14/2023]
Abstract
Werner syndrome (WS) is a heritable autosomal recessive human disorder characterized by the premature onset of several age-associated pathologies including cancer. The protein defective in WS patients, WRN, is encoded by a member of the human RECQ gene family that contains both a DNA exonuclease and a helicase domain. WRN has been shown to participate in several DNA metabolic pathways including DNA replication, recombination and repair, as well as telomere maintenance and transcription modulation. Here we review base pair-level genetic variation that has been documented in WRN, with an emphasis on non-synonymous coding single nucleotide polymorphisms (SNPs) and their associations with anthropomorphic features, longevity and disease risk. These associations have been challenging to identify, as many reported WRN SNP associations appear to be further conditioned upon ethnic, age, gender or other environmental co-variables. The WRN variant phenotypic associations identified to date are intriguing, and several are of clear clinical import. Consequently, it will be important to extend these initial associations and to identify the mechanisms and conditions under which specific WRN variants may compromise WRN function to drive cellular and organismal phenotypes as well as disease risk.
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Affiliation(s)
- Michel Lebel
- Centre de recherche du CHU de Québec, Pavillon CHUL Université Laval, Faculté de Médecine, Québec City, Québec, G1V 4G2, Canada.
| | - Raymond J Monnat
- Departments of Pathology and Genome Sciences, University of Washington, Seattle, WA 98195, USA
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54
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RecQ and Fe-S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions. Biochem Soc Trans 2017; 46:77-95. [PMID: 29273621 DOI: 10.1042/bst20170044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022]
Abstract
Helicases are molecular motors that play central roles in nucleic acid metabolism. Mutations in genes encoding DNA helicases of the RecQ and iron-sulfur (Fe-S) helicase families are linked to hereditary disorders characterized by chromosomal instabilities, highlighting the importance of these enzymes. Moreover, mono-allelic RecQ and Fe-S helicase mutations are associated with a broad spectrum of cancers. This review will discuss and contrast the specialized molecular functions and biological roles of RecQ and Fe-S helicases in DNA repair, the replication stress response, and the regulation of gene expression, laying a foundation for continued research in these important areas of study.
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55
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Tavakoli Shirazi P, Leifert WR, Fenech MF, François M. Folate modulates guanine-quadruplex frequency and DNA damage in Werner syndrome. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2017; 826:47-52. [PMID: 29412869 DOI: 10.1016/j.mrgentox.2017.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 09/20/2017] [Accepted: 12/07/2017] [Indexed: 12/21/2022]
Abstract
Guanine-quadruplexes (G4) are stable tetra-stranded DNA structures that may cause DNA replication stress and inhibit gene expression. Defects in unwinding these structures by DNA helicases may result in telomere shortening and DNA damage. Furthermore, due to mutations in WRN helicase genes in Werner syndrome, G4 motifs are likely to be key elements in the expression of premature aging phenotypes. The methylation of DNA plays a significant role in the stability and occurrence of G4. Thus, G4 frequency and DNA methylation mechanisms may be affected by excesses or deficiencies in methyl donors such as folate. B-Lymphocytes from Werner patients (n = 5) and healthy individuals (n = 5) were cultured in RPMI medium under condition of folate deficiency (20 nM) or sufficiency (200 nM) for 14 days. Cells were fixed on microscope slides for immunofluorescent staining to measure G4 frequency and γH2AX (a marker of DNA strand breaks) intensity, using automated quantitative imaging fluorescent microscopy. There was a significant increase (p < 0.05) in G4 levels in Werner syndrome patients compared to healthy controls. Werner and control cells grown in 20 nM folate media also showed significant increases in G4 (p < 0.001) and γH2AX (p < 0.01) signals compared with the same cells grown in 200 nM folate. Control cells grown in 20 nM folate also showed a significant reduction in DNA methylation levels (P < 0.05). The results of this study suggest that the occurrence of DNA G4 structures can be modulated in vitro via nutrients with important roles in methylation.
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Affiliation(s)
- Paniz Tavakoli Shirazi
- CSIRO Health and Biosecurity, Personalised Nutrition & Healthy Ageing, Gate 13, Kintore Ave, Adelaide, South Australia, 5000, Australia; University of Adelaide, Department of Molecular and Cellular Biology, School of Biological Sciences, Adelaide, South Australia, 5005, Australia; South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, 5000, Australia.
| | - Wayne Richard Leifert
- CSIRO Health and Biosecurity, Personalised Nutrition & Healthy Ageing, Gate 13, Kintore Ave, Adelaide, South Australia, 5000, Australia; University of Adelaide, Department of Molecular and Cellular Biology, School of Biological Sciences, Adelaide, South Australia, 5005, Australia.
| | - Michael Felix Fenech
- CSIRO Health and Biosecurity, Personalised Nutrition & Healthy Ageing, Gate 13, Kintore Ave, Adelaide, South Australia, 5000, Australia.
| | - Maxime François
- CSIRO Health and Biosecurity, Personalised Nutrition & Healthy Ageing, Gate 13, Kintore Ave, Adelaide, South Australia, 5000, Australia; University of Adelaide, Department of Molecular and Cellular Biology, School of Biological Sciences, Adelaide, South Australia, 5005, Australia.
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56
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Abstract
Aging, the universal phenomenon, affects human health and is the primary risk factor for major disease pathologies. Progeroid diseases, which mimic aging at an accelerated rate, have provided cues in understanding the hallmarks of aging. Mutations in DNA repair genes as well as in telomerase subunits are known to cause progeroid syndromes. Werner syndrome (WS), which is characterized by accelerated aging, is an autosomal-recessive genetic disorder. Hallmarks that define the aging process include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulation of nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. WS recapitulates these hallmarks of aging and shows increased incidence and early onset of specific cancers. Genome integrity and stability ensure the normal functioning of the cell and are mainly guarded by the DNA repair machinery and telomeres. WRN, being a RecQ helicase, protects genome stability by regulating DNA repair pathways and telomeres. Recent advances in WS research have elucidated WRN’s role in DNA repair pathway choice regulation, telomere maintenance, resolution of complex DNA structures, epigenetic regulation, and stem cell maintenance.
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Affiliation(s)
- Raghavendra A Shamanna
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Jong-Hyuk Lee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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57
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Rogers CM, Wang JCY, Noguchi H, Imasaki T, Takagi Y, Bochman ML. Yeast Hrq1 shares structural and functional homology with the disease-linked human RecQ4 helicase. Nucleic Acids Res 2017; 45:5217-5230. [PMID: 28334827 PMCID: PMC5605238 DOI: 10.1093/nar/gkx151] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 02/22/2017] [Indexed: 12/14/2022] Open
Abstract
The five human RecQ helicases participate in multiple processes required to maintain genome integrity. Of these, the disease-linked RecQ4 is the least studied because it poses many technical challenges. We previously demonstrated that the yeast Hrq1 helicase displays similar functions to RecQ4 in vivo, and here, we report the biochemical and structural characterization of these enzymes. In vitro, Hrq1 and RecQ4 are DNA-stimulated ATPases and robust helicases. Further, these activities were sensitive to DNA sequence and structure, with the helicases preferentially unwinding D-loops. Consistent with their roles at telomeres, telomeric repeat sequence DNA also stimulated binding and unwinding by these enzymes. Finally, electron microscopy revealed that Hrq1 and RecQ4 share similar structural features. These results solidify Hrq1 as a true RecQ4 homolog and position it as the premier model to determine how RecQ4 mutations lead to genomic instability and disease.
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Affiliation(s)
- Cody M Rogers
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | | | - Hiroki Noguchi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Tsuyoshi Imasaki
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yuichiro Takagi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Matthew L Bochman
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
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58
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Fleming AM, Burrows CJ. Formation and processing of DNA damage substrates for the hNEIL enzymes. Free Radic Biol Med 2017; 107:35-52. [PMID: 27880870 PMCID: PMC5438787 DOI: 10.1016/j.freeradbiomed.2016.11.030] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/13/2016] [Accepted: 11/16/2016] [Indexed: 12/13/2022]
Abstract
Reactive oxygen species (ROS) are harnessed by the cell for signaling at the same time as being detrimental to cellular components such as DNA. The genome and transcriptome contain instructions that can alter cellular processes when oxidized. The guanine (G) heterocycle in the nucleotide pool, DNA, or RNA is the base most prone to oxidation. The oxidatively-derived products of G consistently observed in high yields from hydroxyl radical, carbonate radical, or singlet oxygen oxidations under conditions modeling the cellular reducing environment are discussed. The major G base oxidation products are 8-oxo-7,8-dihydroguanine (OG), 5-carboxamido-5-formamido-2-iminohydantoin (2Ih), spiroiminodihydantoin (Sp), and 5-guanidinohydantoin (Gh). The yields of these products show dependency on the oxidant and the reaction context that includes nucleoside, single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), and G-quadruplex DNA (G4-DNA) structures. Upon formation of these products in cells, they are recognized by the DNA glycosylases in the base excision repair (BER) pathway. This review focuses on initiation of BER by the mammalian Nei-like1-3 (NEIL1-3) glycosylases for removal of 2Ih, Sp, and Gh. The unique ability of the human NEILs to initiate removal of the hydantoins in ssDNA, bulge-DNA, bubble-DNA, dsDNA, and G4-DNA is outlined. Additionally, when Gh exists in a G4 DNA found in a gene promoter, NEIL-mediated repair is modulated by the plasticity of the G4-DNA structure provided by additional G-runs flanking the sequence. On the basis of these observations and cellular studies from the literature, the interplay between DNA oxidation and BER to alter gene expression is discussed.
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Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah, 315 S 1400 East, Salt Lake City, UT 84112-0850, United States
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, 315 S 1400 East, Salt Lake City, UT 84112-0850, United States.
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59
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Caravia XM, Roiz-Valle D, Morán-Álvarez A, López-Otín C. Functional relevance of miRNAs in premature ageing. Mech Ageing Dev 2017; 168:10-19. [PMID: 28502819 DOI: 10.1016/j.mad.2017.05.003] [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: 10/25/2016] [Revised: 03/30/2017] [Accepted: 05/09/2017] [Indexed: 02/06/2023]
Abstract
Ageing is a complex biological process characterized by the progressive loss of biological fitness due to the accumulation of macromolecular and cellular damage that affects most living organisms. Moreover, ageing is an important risk factor for many pathologies, including cardiovascular diseases, neurological disorders, and cancer. However, the ageing rate can be modulated by genetic, nutritional, and pharmacological factors, highlighting the concept of "ageing plasticity". Progeroid syndromes are a group of rare genetic diseases that resemble many characteristics of physiological ageing. Accordingly, studies on these diseases have been very useful for gaining mechanistic insights in ageing biology. In recent years, a great effort has been made in ageing research and several works have confirmed that geromiRs, the growing subgroup of miRNAs implicated in ageing, are able to modulate organismal lifespan. However, very little is still known about the impact of miRNA in premature ageing. In this review, we will address the functional relevance of this class of small non-coding RNAs in the regulation of the hallmarks of progeroid syndromes. In addition, we will discuss the potential strategies for managing progeria based on geromiR modulation.
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Affiliation(s)
- Xurde M Caravia
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - David Roiz-Valle
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - Alba Morán-Álvarez
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain
| | - Carlos López-Otín
- Departamento de Bioquímica y Biología Molecular, Instituto Universitario de Oncología (IUOPA), Universidad de Oviedo, 33006 Oviedo, Spain; Centro de Investigación Biomédica en Red de Cáncer, Spain.
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60
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Zhao Y, Zhang JY, Zhang ZY, Tong TJ, Hao YH, Tan Z. Real-Time Detection Reveals Responsive Cotranscriptional Formation of Persistent Intramolecular DNA and Intermolecular DNA:RNA Hybrid G-Quadruplexes Stabilized by R-Loop. Anal Chem 2017; 89:6036-6042. [DOI: 10.1021/acs.analchem.7b00625] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yang Zhao
- Department
of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Peking University Research Center on Aging, Beijing 100083, P.R. China
| | - Jia-yu Zhang
- State
Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Zong-yu Zhang
- Department
of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Peking University Research Center on Aging, Beijing 100083, P.R. China
| | - Tan-jun Tong
- Department
of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Peking University Research Center on Aging, Beijing 100083, P.R. China
| | - Yu-hua Hao
- State
Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Zheng Tan
- State
Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
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61
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Hänsel-Hertsch R, Di Antonio M, Balasubramanian S. DNA G-quadruplexes in the human genome: detection, functions and therapeutic potential. Nat Rev Mol Cell Biol 2017; 18:279-284. [PMID: 28225080 DOI: 10.1038/nrm.2017.3] [Citation(s) in RCA: 596] [Impact Index Per Article: 85.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Single-stranded guanine-rich DNA sequences can fold into four-stranded DNA structures called G-quadruplexes (G4s) that arise from the self-stacking of two or more guanine quartets. There has been considerable recent progress in the detection and mapping of G4 structures in the human genome and in biologically relevant contexts. These advancements, many of which align with predictions made previously in computational studies, provide important new insights into the functions of G4 structures in, for example, the regulation of transcription and genome stability, and uncover their potential relevance for cancer therapy.
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Affiliation(s)
- Robert Hänsel-Hertsch
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge CB2 0RE, UK
| | - Marco Di Antonio
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge CB2 0RE, UK
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - Shankar Balasubramanian
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge CB2 0RE, UK
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
- School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SP, UK
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62
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Griffin WC, Gao J, Byrd AK, Chib S, Raney KD. A biochemical and biophysical model of G-quadruplex DNA recognition by positive coactivator of transcription 4. J Biol Chem 2017; 292:9567-9582. [PMID: 28416612 DOI: 10.1074/jbc.m117.776211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/14/2017] [Indexed: 12/22/2022] Open
Abstract
DNA sequences that are guanine-rich have received considerable attention because of their potential to fold into a secondary, four-stranded DNA structure termed G-quadruplex (G4), which has been implicated in genomic instability and some human diseases. We have previously identified positive coactivator of transcription (PC4), a single-stranded DNA (ssDNA)-binding protein, as a novel G4 interactor. Here, to expand on these previous observations, we biochemically and biophysically characterized the interaction between PC4 and G4DNA. PC4 can bind alternative G4DNA topologies with a low nanomolar Kd value of ∼2 nm, similar to that observed for ssDNA. In consideration of the different structural features between G4DNA and ssDNA, these binding data indicated that PC4 can interact with G4DNA in a manner distinct from ssDNA. The stoichiometry of the PC4-G4 complex was 1:1 for PC4 dimer:G4 substrate. PC4 did not enhance the rate of folding of G4DNA, and formation of the PC4-G4DNA complex did not result in unfolding of the G4DNA structure. We assembled a G4DNA structure flanked by duplex DNA. We find that PC4 can interact with this G4DNA, as well as the complementary C-rich strand. Molecular docking simulations and DNA footprinting experiments suggest a model where a PC4 dimer accommodates the DNA with one monomer on the G4 strand and the second monomer bound to the C-rich strand. Collectively, these data provide a novel mode of PC4 binding to a DNA secondary structure that remains within the framework of the model for binding to ssDNA. Additionally, consideration of the PC4-G4DNA interaction could provide insight into the biological functions of PC4, which remain incompletely understood.
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Affiliation(s)
- Wezley C Griffin
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Jun Gao
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Alicia K Byrd
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Shubeena Chib
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
| | - Kevin D Raney
- From the Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7101
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63
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64
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Ketkar A, Voehler M, Mukiza T, Eoff RL. Residues in the RecQ C-terminal Domain of the Human Werner Syndrome Helicase Are Involved in Unwinding G-quadruplex DNA. J Biol Chem 2017; 292:3154-3163. [PMID: 28069813 DOI: 10.1074/jbc.m116.767699] [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: 11/11/2016] [Revised: 01/04/2017] [Indexed: 12/11/2022] Open
Abstract
The structural and biophysical properties typically associated with G-quadruplex (G4) structures render them a significant block for DNA replication, which must be overcome for cell division to occur. The Werner syndrome protein (WRN) is a RecQ family helicase that has been implicated in the efficient processing of G4 DNA structures. The aim of this study was to identify the residues of WRN involved in the binding and ATPase-driven unwinding of G4 DNA. Using a c-Myc G4 DNA model sequence and recombinant WRN, we have determined that the RecQ-C-terminal (RQC) domain of WRN imparts a 2-fold preference for binding to G4 DNA relative to non-G4 DNA substrates. NMR studies identified residues involved specifically in interactions with G4 DNA. Three of the amino acids in the WRN RQC domain that exhibited the largest G4-specific changes in NMR signal were then mutated alone or in combination. Mutating individual residues implicated in G4 binding had a modest effect on WRN binding to DNA, decreasing the preference for G4 substrates by ∼25%. Mutating two G4-interacting residues (T1024G and T1086G) abrogated preferential binding of WRN to G4 DNA. Very modest decreases in G4 DNA-stimulated ATPase activity were observed for the mutant enzymes. Most strikingly, G4 unwinding by WRN was inhibited ∼50% for all three point mutants and >90% for the WRN double mutant (T1024G/T1086G) relative to normal B-form dsDNA substrates. Our work has helped to identify residues in the WRN RQC domain that are involved specifically in the interaction with G4 DNA.
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Affiliation(s)
- Amit Ketkar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Markus Voehler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235
| | - Tresor Mukiza
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Robert L Eoff
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199.
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65
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Bloom's syndrome: Why not premature aging?: A comparison of the BLM and WRN helicases. Ageing Res Rev 2017; 33:36-51. [PMID: 27238185 DOI: 10.1016/j.arr.2016.05.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/17/2016] [Accepted: 05/19/2016] [Indexed: 01/19/2023]
Abstract
Genomic instability is a hallmark of cancer and aging. Premature aging (progeroid) syndromes are often caused by mutations in genes whose function is to ensure genomic integrity. The RecQ family of DNA helicases is highly conserved and plays crucial roles as genome caretakers. In humans, mutations in three RecQ genes - BLM, WRN, and RECQL4 - give rise to Bloom's syndrome (BS), Werner syndrome (WS), and Rothmund-Thomson syndrome (RTS), respectively. WS is a prototypic premature aging disorder; however, the clinical features present in BS and RTS do not indicate accelerated aging. The BLM helicase has pivotal functions at the crossroads of DNA replication, recombination, and repair. BS cells exhibit a characteristic form of genomic instability that includes excessive homologous recombination. The excessive homologous recombination drives the development in BS of the many types of cancers that affect persons in the normal population. Replication delay and slower cell turnover rates have been proposed to explain many features of BS, such as short stature. More recently, aberrant transcriptional regulation of growth and survival genes has been proposed as a hypothesis to explain features of BS.
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66
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Targeted inhibition of WRN helicase, replication stress and cancer. Biochim Biophys Acta Rev Cancer 2016; 1867:42-48. [PMID: 27902925 DOI: 10.1016/j.bbcan.2016.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/16/2016] [Accepted: 11/24/2016] [Indexed: 11/21/2022]
Abstract
WRN helicase has several roles in genome maintenance, such as replication, base excision repair, recombination, DNA damage response and transcription. These processes are often found upregulated in human cancers, many of which display increased levels of WRN. Therefore, directed inhibition of this RecQ helicase could be beneficial to selective cancer therapy. Inhibition of WRN is feasible by the use of small-molecule inhibitors or application of RNA interference and EGS/RNase P targeting systems. Remarkably, helicase depletion leads to a severe reduction in cell viability due to mitotic catastrophe, which is triggered by replication stress induced by DNA repair failure and fork progression arrest. Moreover, we present new evidence that WRN depletion results in early changes of RNA polymerase III and RNase P activities, thereby implicating chromatin-associated tRNA enzymes in WRN-related stress response. Combined with the recently discovered roles of RecQ helicases in cancer, current data support the targeting prospect of these genome guardians, as a means of developing clinical phases aimed at diminishing adaptive resistance to present targeted therapies.
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67
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Tokita M, Kennedy SR, Risques RA, Chun SG, Pritchard C, Oshima J, Liu Y, Bryant-Greenwood PK, Welcsh P, Monnat RJ. Werner syndrome through the lens of tissue and tumour genomics. Sci Rep 2016; 6:32038. [PMID: 27559010 PMCID: PMC4997333 DOI: 10.1038/srep32038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/01/2016] [Indexed: 12/11/2022] Open
Abstract
Werner syndrome (WS) is the canonical adult human progeroid ('premature aging') syndrome. Patients with this autosomal recessive Mendelian disorder display constitutional genomic instability and an elevated risk of important age-associated diseases including cancer. Remarkably few analyses of WS patient tissue and tumors have been performed to provide insight into WS disease pathogenesis or the high risk of neoplasia. We used autopsy tissue from four mutation-typed WS patients to characterize pathologic and genomic features of WS, and to determine genomic features of three neoplasms arising in two of these patients. The results of these analyses provide new information on WS pathology and genomics; provide a first genomic characterization of neoplasms arising in WS; and provide new histopathologic and genomic data to test several popular models of WS disease pathogenesis.
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Affiliation(s)
- Mari Tokita
- Department of Medicine Division of Medical Genetics, University of Washington, Seattle, WA USA
| | - Scott R. Kennedy
- Department of Pathology, University of Washington, Seattle, WA USA
| | - Rosa Ana Risques
- Department of Pathology, University of Washington, Seattle, WA USA
| | - Stephen G. Chun
- Department of Radiation Oncology, MD Anderson Cancer Center, Houston, TX USA
| | - Colin Pritchard
- Department of Laboratory Medicine, University of Washington, Seattle, WA USA
| | - Junko Oshima
- Department of Pathology, University of Washington, Seattle, WA USA
- Department of Medicine, Chiba University, Chiba, Japan
| | - Yan Liu
- Department of Pathology, University of Washington, Seattle, WA USA
| | - Peter K. Bryant-Greenwood
- Department of Pathology, John Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI USA
| | - Piri Welcsh
- Department of Pathology, University of Washington, Seattle, WA USA
| | - Raymond J. Monnat
- Department of Pathology, University of Washington, Seattle, WA USA
- Department of Genome Sciences, University of Washington, Seattle, WA USA
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68
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Getting Ready for the Dance: FANCJ Irons Out DNA Wrinkles. Genes (Basel) 2016; 7:genes7070031. [PMID: 27376332 PMCID: PMC4962001 DOI: 10.3390/genes7070031] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/13/2016] [Accepted: 06/27/2016] [Indexed: 12/21/2022] Open
Abstract
Mounting evidence indicates that alternate DNA structures, which deviate from normal double helical DNA, form in vivo and influence cellular processes such as replication and transcription. However, our understanding of how the cellular machinery deals with unusual DNA structures such as G-quadruplexes (G4), triplexes, or hairpins is only beginning to emerge. New advances in the field implicate a direct role of the Fanconi Anemia Group J (FANCJ) helicase, which is linked to a hereditary chromosomal instability disorder and important for cancer suppression, in replication past unusual DNA obstacles. This work sets the stage for significant progress in dissecting the molecular mechanisms whereby replication perturbation by abnormal DNA structures leads to genomic instability. In this review, we focus on FANCJ and its role to enable efficient DNA replication when the fork encounters vastly abundant naturally occurring DNA obstacles, which may have implications for targeting rapidly dividing cancer cells.
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69
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Lu X, Parvathaneni S, Li XL, Lal A, Sharma S. Transcriptome guided identification of novel functions of RECQ1 helicase. Methods 2016; 108:111-7. [PMID: 27102625 DOI: 10.1016/j.ymeth.2016.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/14/2016] [Accepted: 04/15/2016] [Indexed: 01/22/2023] Open
Abstract
Gene expression changes in the functional absence of a specific RecQ protein, and how that relates to disease outcomes including cancer predisposition and premature aging in RecQ helicase associated syndromes, are poorly understood. Here we describe detailed experimental strategy for identification of RECQ1-regulated transcriptome that led us to uncover a novel association of RECQ1 in regulation of cancer cell migration and invasion. We initiated a focused study to determine whether RECQ1, the most abundant RecQ protein in humans, alters gene expression and also investigated whether RECQ1 binds with G4 motifs predicted to form G-quadruplex structures in the target gene promoters. Rescue of mRNA expression of select RECQ1-downregulated genes harboring G4 motifs required wild-type RECQ1 helicase. However, some RECQ1-regulated genes are also regulated by BLM and WRN proteins regardless of the presence or absence of G4 motifs. The approach described here is applicable for systematic comparison of gene expression signatures of individual RecQ proteins in isogenic background, and to elucidate their participation in transcription regulation through G-quadruplex recognition and/or resolution. Such strategies might also reveal molecular pathways that drive the pathogenesis of cancer and other diseases in specific RecQ deficiency.
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Affiliation(s)
- Xing Lu
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA
| | - Swetha Parvathaneni
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA
| | - Xiao Ling Li
- Regulatory RNAs and Cancer Section, Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ashish Lal
- Regulatory RNAs and Cancer Section, Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sudha Sharma
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA.
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