51
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Popova VV, Brechalov AV, Georgieva SG, Kopytova DV. Nonreplicative functions of the origin recognition complex. Nucleus 2018; 9:460-473. [PMID: 30196754 PMCID: PMC6244734 DOI: 10.1080/19491034.2018.1516484] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/04/2018] [Accepted: 08/16/2018] [Indexed: 12/14/2022] Open
Abstract
Origin recognition complex (ORC), a heteromeric six-subunit complex, is the central component of the eukaryotic pre-replication complex. Recent data from yeast, frogs, flies and mammals present compelling evidence that ORC and its individual subunits have nonreplicative functions as well. The majority of these functions, such as heterochromatin formation, chromosome condensation, and segregation are dependent on ORC-DNA interactions. Furthermore, ORC is involved in the control of cell division via its participation in centrosome duplication and cytokinesis. Recent findings have also demonstrated a direct interaction between ORC and mRNPs and highlighted an essential role of ORC in mRNA nuclear export. Along with the growth of evolutionary complexity of organisms, ORC complex functions become more elaborate and new functions of the ORC sub-complexes and individual subunits have emerged.
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Affiliation(s)
- Varvara V. Popova
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Alexander V. Brechalov
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Sofia G. Georgieva
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Daria V. Kopytova
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
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52
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Bergman J, Betancourt AJ, Vogl C. Transcription-Associated Compositional Skews in Drosophila Genes. Genome Biol Evol 2018; 10:269-275. [PMID: 29036491 PMCID: PMC5786239 DOI: 10.1093/gbe/evx200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2017] [Indexed: 12/23/2022] Open
Abstract
In many organisms, local deviations from Chargaff's second parity rule are observed around replication and transcription start sites and within intron sequences. Here, we use expression data as well as a whole-genome data set of nearly 200 haplotypes to investigate such compositional skews in Drosophila melanogaster genes. We find a positive correlation between compositional skew and gene expression, comparable in strength to similar correlations between expression levels and genome-wide sequence features. This correlation is relatively stronger for germline, compared with somatic expression, consistent with the process of transcription-associated mutation bias. We also inferred mutation rates from alleles segregating at low frequencies in short introns, and show that, whereas the overall GC content of short introns does not conform to the equilibrium expectation, the level of the observed deviation from the second parity rule is generally consistent with the inferred rates.
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Affiliation(s)
- Juraj Bergman
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
- Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Wien, Austria
| | - Andrea J Betancourt
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
- Present address: Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Claus Vogl
- Institut für Tierzucht und Genetik, Vetmeduni Vienna, Wien, Austria
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53
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Vergara Z, Sequeira-Mendes J, Morata J, Peiró R, Hénaff E, Costas C, Casacuberta JM, Gutierrez C. Retrotransposons are specified as DNA replication origins in the gene-poor regions of Arabidopsis heterochromatin. Nucleic Acids Res 2017; 45:8358-8368. [PMID: 28605523 PMCID: PMC5737333 DOI: 10.1093/nar/gkx524] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 06/05/2017] [Indexed: 12/28/2022] Open
Abstract
Genomic stability depends on faithful genome replication. This is achieved by the concerted activity of thousands of DNA replication origins (ORIs) scattered throughout the genome. The DNA and chromatin features determining ORI specification are not presently known. We have generated a high-resolution genome-wide map of 3230 ORIs in cultured Arabidopsis thaliana cells. Here, we focused on defining the features associated with ORIs in heterochromatin. In pericentromeric gene-poor domains ORIs associate almost exclusively with the retrotransposon class of transposable elements (TEs), in particular of the Gypsy family. ORI activity in retrotransposons occurs independently of TE expression and while maintaining high levels of H3K9me2 and H3K27me1, typical marks of repressed heterochromatin. ORI-TEs largely colocalize with chromatin signatures defining GC-rich heterochromatin. Importantly, TEs with active ORIs contain a local GC content higher than the TEs lacking them. Our results lead us to conclude that ORI colocalization with retrotransposons is determined by their transposition mechanism based on transcription, and a specific chromatin landscape. Our detailed analysis of ORIs responsible for heterochromatin replication has implications on the mechanisms of ORI specification in other multicellular organisms in which retrotransposons are major components of heterochromatin and of the entire genome.
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Affiliation(s)
- Zaida Vergara
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Joana Sequeira-Mendes
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Jordi Morata
- Center for Research in Agricultural Genomics, CRAG (CSIC-IRTA-UAB-UB), Campus Universitat Autónoma de Barcelona, Bellaterra, Cerdanyola del Valles, 08193 Barcelona, Spain
| | - Ramón Peiró
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Elizabeth Hénaff
- Center for Research in Agricultural Genomics, CRAG (CSIC-IRTA-UAB-UB), Campus Universitat Autónoma de Barcelona, Bellaterra, Cerdanyola del Valles, 08193 Barcelona, Spain
| | - Celina Costas
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain
| | - Josep M Casacuberta
- Center for Research in Agricultural Genomics, CRAG (CSIC-IRTA-UAB-UB), Campus Universitat Autónoma de Barcelona, Bellaterra, Cerdanyola del Valles, 08193 Barcelona, Spain
| | - Crisanto Gutierrez
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Cantoblanco, 28049 Madrid, Spain
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54
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Bournique E, Dall'Osto M, Hoffmann JS, Bergoglio V. Role of specialized DNA polymerases in the limitation of replicative stress and DNA damage transmission. Mutat Res 2017; 808:62-73. [PMID: 28843435 DOI: 10.1016/j.mrfmmm.2017.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 01/31/2023]
Abstract
Replication stress is a strong and early driving force for genomic instability and tumor development. Beside replicative DNA polymerases, an emerging group of specialized DNA polymerases is involved in the technical assistance of the replication machinery in order to prevent replicative stress and its deleterious consequences. During S-phase, altered progression of the replication fork by endogenous or exogenous impediments induces replicative stress, causing cells to reach mitosis with genomic regions not fully duplicated. Recently, specific mechanisms to resolve replication intermediates during mitosis with the aim of limiting DNA damage transmission to daughter cells have been identified. In this review, we detail the two major actions of specialized DNA polymerases that limit DNA damage transmission: the prevention of replicative stress by non-B DNA replication and the recovery of stalled replication forks.
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Affiliation(s)
- Elodie Bournique
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France
| | - Marina Dall'Osto
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France
| | - Jean-Sébastien Hoffmann
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France
| | - Valérie Bergoglio
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France.
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55
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Agarwal M, Bhowmick K, Shah K, Krishnamachari A, Dhar SK. Identification and characterization of ARS-like sequences as putative origin(s) of replication in human malaria parasite Plasmodium falciparum. FEBS J 2017. [PMID: 28644560 DOI: 10.1111/febs.14150] [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] [Indexed: 01/23/2023]
Abstract
DNA replication is a fundamental process in genome maintenance, and initiates from several genomic sites (origins) in eukaryotes. In Saccharomyces cerevisiae, conserved sequences known as autonomously replicating sequences (ARSs) provide a landing pad for the origin recognition complex (ORC), leading to replication initiation. Although origins from higher eukaryotes share some common sequence features, the definitive genomic organization of these sites remains elusive. The human malaria parasite Plasmodium falciparum undergoes multiple rounds of DNA replication; therefore, control of initiation events is crucial to ensure proper replication. However, the sites of DNA replication initiation and the mechanism by which replication is initiated are poorly understood. Here, we have identified and characterized putative origins in P. falciparum by bioinformatics analyses and experimental approaches. An autocorrelation measure method was initially used to search for regions with marked fluctuation (dips) in the chromosome, which we hypothesized might contain potential origins. Indeed, S. cerevisiae ARS consensus sequences were found in dip regions. Several of these P. falciparum sequences were validated with chromatin immunoprecipitation-quantitative PCR, nascent strand abundance and a plasmid stability assay. Subsequently, the same sequences were used in yeast to confirm their potential as origins in vivo. Our results identify the presence of functional ARSs in P. falciparum and provide meaningful insights into replication origins in these deadly parasites. These data could be useful in designing transgenic vectors with improved stability for transfection in P. falciparum.
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Affiliation(s)
- Meetu Agarwal
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Krishanu Bhowmick
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Kushal Shah
- Department of Electrical Engineering, Indian Institute of Technology, New Delhi, India
| | | | - Suman Kumar Dhar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
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56
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Abstract
In this review, Prioleau and MacAlpine summarize recent advances in our understanding of how primary sequence, chromatin environment, and nuclear architecture contribute to the dynamic selection and activation of replication origins across diverse cell types and developmental stages. For more than three decades, investigators have sought to identify the precise locations where DNA replication initiates in mammalian genomes. The development of molecular and biochemical approaches to identify start sites of DNA replication (origins) based on the presence of defining and characteristic replication intermediates at specific loci led to the identification of only a handful of mammalian replication origins. The limited number of identified origins prevented a comprehensive and exhaustive search for conserved genomic features that were capable of specifying origins of DNA replication. More recently, the adaptation of origin-mapping assays to genome-wide approaches has led to the identification of tens of thousands of replication origins throughout mammalian genomes, providing an unprecedented opportunity to identify both genetic and epigenetic features that define and regulate their distribution and utilization. Here we summarize recent advances in our understanding of how primary sequence, chromatin environment, and nuclear architecture contribute to the dynamic selection and activation of replication origins across diverse cell types and developmental stages.
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Affiliation(s)
- Marie-Noëlle Prioleau
- Institut Jacques Monod, UMR7592, Centre National de la Recherche Scientifique, Universite Paris Diderot, Equipe Labellisee Association pour la Recherche sur le Cancer, Paris 75013, France
| | - David M MacAlpine
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710. USA
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57
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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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58
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DNA Replication Origins and Fork Progression at Mammalian Telomeres. Genes (Basel) 2017; 8:genes8040112. [PMID: 28350373 PMCID: PMC5406859 DOI: 10.3390/genes8040112] [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: 02/07/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions.
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59
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Dolinnaya NG, Ogloblina AM, Yakubovskaya MG. Structure, Properties, and Biological Relevance of the DNA and RNA G-Quadruplexes: Overview 50 Years after Their Discovery. BIOCHEMISTRY (MOSCOW) 2017; 81:1602-1649. [PMID: 28260487 PMCID: PMC7087716 DOI: 10.1134/s0006297916130034] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
G-quadruplexes (G4s), which are known to have important roles in regulation of key biological processes in both normal and pathological cells, are the most actively studied non-canonical structures of nucleic acids. In this review, we summarize the results of studies published in recent years that change significantly scientific views on various aspects of our understanding of quadruplexes. Modern notions on the polymorphism of DNA quadruplexes, on factors affecting thermodynamics and kinetics of G4 folding–unfolding, on structural organization of multiquadruplex systems, and on conformational features of RNA G4s and hybrid DNA–RNA G4s are discussed. Here we report the data on location of G4 sequence motifs in the genomes of eukaryotes, bacteria, and viruses, characterize G4-specific small-molecule ligands and proteins, as well as the mechanisms of their interactions with quadruplexes. New information on the structure and stability of G4s in telomeric DNA and oncogene promoters is discussed as well as proof being provided on the occurrence of G-quadruplexes in cells. Prominence is given to novel experimental techniques (single molecule manipulations, optical and magnetic tweezers, original chemical approaches, G4 detection in situ, in-cell NMR spectroscopy) that facilitate breakthroughs in the investigation of the structure and functions of G-quadruplexes.
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Affiliation(s)
- N G Dolinnaya
- Lomonosov Moscow State University, Department of Chemistry, Moscow, 119991, Russia.
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60
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Köhler C, Koalick D, Fabricius A, Parplys AC, Borgmann K, Pospiech H, Grosse F. Cdc45 is limiting for replication initiation in humans. Cell Cycle 2017; 15:974-85. [PMID: 26919204 PMCID: PMC4889307 DOI: 10.1080/15384101.2016.1152424] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cdc45 is an essential protein that together with Mcm2-7 and GINS forms the eukaryotic replicative helicase CMG. Cdc45 seems to be rate limiting for the initial unwinding or firing of replication origins. In line with this view, Cdc45-overexpressing cells fired at least twice as many origins as control cells. However, these cells displayed an about 2-fold diminished fork elongation rate, a pronounced asymmetry of replication fork extension, and an early S phase arrest. This was accompanied by H2AX-phosphorylation and subsequent apoptosis. Unexpectedly, we did not observe increased ATR/Chk1 signaling but rather a mild ATM/Chk2 response. In addition, we detected accumulation of long stretches of single-stranded DNA, a hallmark of replication catastrophe. We conclude that increased origin firing by upregulated Cdc45 caused exhaustion of the single-strand binding protein RPA, which in consequence diminished the ATR/Chk1 response; the subsequently occurring fork breaks led to an ATM/Chk2 mediated phosphorylation of H2AX and eventually to apoptosis.
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Affiliation(s)
- Carsten Köhler
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany
| | - Dennis Koalick
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany
| | - Anja Fabricius
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany
| | - Ann Christin Parplys
- b Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Kerstin Borgmann
- b Laboratory of Radiobiology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Helmut Pospiech
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany.,c Faculty of Biochemistry and Molecular Medicine, University of Oulu , Finland
| | - Frank Grosse
- a Research group Biochemistry, Leibniz Institute for Age Research - Fritz Lipmann Institute , Jena , Germany.,d Centre for Molecular Biomedicine, Friedrich-Schiller University , Jena , Germany
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61
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Rodríguez-Martínez M, Pinzón N, Ghommidh C, Beyne E, Seitz H, Cayrou C, Méchali M. The gastrula transition reorganizes replication-origin selection in Caenorhabditis elegans. Nat Struct Mol Biol 2017; 24:290-299. [PMID: 28112731 DOI: 10.1038/nsmb.3363] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 12/13/2016] [Indexed: 01/09/2023]
Abstract
Although some features underlying replication-origin activation in metazoan cells have been determined, little is known about their regulation during metazoan development. Using the nascent-strand purification method, here we identified replication origins throughout Caenorhabditis elegans embryonic development and found that the origin repertoire is thoroughly reorganized after gastrulation onset. During the pluripotent embryonic stages (pregastrula), potential cruciform structures and open chromatin are determining factors that establish replication origins. The observed enrichment of replication origins in transcription factor-binding sites and their presence in promoters of highly transcribed genes, particularly operons, suggest that transcriptional activity contributes to replication initiation before gastrulation. After the gastrula transition, when embryonic differentiation programs are set, new origins are selected at enhancers, close to CpG-island-like sequences, and at noncoding genes. Our findings suggest that origin selection coordinates replication initiation with transcriptional programs during metazoan development.
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Affiliation(s)
| | | | - Charles Ghommidh
- Agropolymer Engineering and Emerging Technologies, University of Montpellier, Montpellier, France
| | | | - Hervé Seitz
- Institute of Human Genetics, CNRS, Montpellier, France
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62
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Parker MW, Botchan MR, Berger JM. Mechanisms and regulation of DNA replication initiation in eukaryotes. Crit Rev Biochem Mol Biol 2017; 52:107-144. [PMID: 28094588 DOI: 10.1080/10409238.2016.1274717] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cellular DNA replication is initiated through the action of multiprotein complexes that recognize replication start sites in the chromosome (termed origins) and facilitate duplex DNA melting within these regions. In a typical cell cycle, initiation occurs only once per origin and each round of replication is tightly coupled to cell division. To avoid aberrant origin firing and re-replication, eukaryotes tightly regulate two events in the initiation process: loading of the replicative helicase, MCM2-7, onto chromatin by the origin recognition complex (ORC), and subsequent activation of the helicase by its incorporation into a complex known as the CMG. Recent work has begun to reveal the details of an orchestrated and sequential exchange of initiation factors on DNA that give rise to a replication-competent complex, the replisome. Here, we review the molecular mechanisms that underpin eukaryotic DNA replication initiation - from selecting replication start sites to replicative helicase loading and activation - and describe how these events are often distinctly regulated across different eukaryotic model organisms.
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Affiliation(s)
- Matthew W Parker
- a Department of Biophysics and Biophysical Chemistry , Johns Hopkins University School of Medicine , Baltimore , MD , USA
| | - Michael R Botchan
- b Department of Molecular and Cell Biology , University of California Berkeley , Berkeley , CA , USA
| | - James M Berger
- a Department of Biophysics and Biophysical Chemistry , Johns Hopkins University School of Medicine , Baltimore , MD , USA
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63
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Prioleau MN. G-Quadruplexes and DNA Replication Origins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:273-286. [DOI: 10.1007/978-981-10-6955-0_13] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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64
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Sugimoto N, Fujita M. Molecular Mechanism for Chromatin Regulation During MCM Loading in Mammalian Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:61-78. [PMID: 29357053 DOI: 10.1007/978-981-10-6955-0_3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
DNA replication is a fundamental process required for the accurate and timely duplication of chromosomes. During late mitosis to G1 phase, the MCM2-7 complex is loaded onto chromatin in a manner dependent on ORC, CDC6, and Cdt1, and chromatin becomes licensed for replication. Although every eukaryotic organism shares common features in replication control, there are also some differences among species. For example, in higher eukaryotic cells including human cells, no strict sequence specificity has been observed for replication origins, unlike budding yeast or bacterial replication origins. Therefore, elements other than beyond DNA sequences are important for regulating replication. For example, the stability and precise positioning of nucleosomes affects replication control. However, little is known about how nucleosome structure is regulated when replication licensing occurs. During the last decade, histone acetylation enzyme HBO1, chromatin remodeler SNF2H, and histone chaperone GRWD1 have been identified as chromatin-handling factors involved in the promotion of replication licensing. In this review, we discuss how the rearrangement of nucleosome formation by these factors affects replication licensing.
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Affiliation(s)
- Nozomi Sugimoto
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
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65
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Moriyama K, Lai MS, Masai H. Interaction of Rif1 Protein with G-Quadruplex in Control of Chromosome Transactions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:287-310. [PMID: 29357064 DOI: 10.1007/978-981-10-6955-0_14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Recent studies on G-quadruplex (G4) revealed crucial and conserved functions of G4 in various biological systems. We recently showed that Rif1, a conserved nuclear factor, binds to G4 present in the intergenic regions and plays a major role in spatiotemporal regulation of DNA replication. Rif1 may tether chromatin fibers through binding to G4, generating specific chromatin domains that dictate the replication timing. G4 and its various binding partners are now implicated in many other chromosome regulations, including transcription, replication initiation, recombination, gene rearrangement, and transposition.
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Affiliation(s)
- Kenji Moriyama
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Mong Sing Lai
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Hisao Masai
- Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan.
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66
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Stadlbauer P, Mazzanti L, Cragnolini T, Wales DJ, Derreumaux P, Pasquali S, Šponer J. Coarse-Grained Simulations Complemented by Atomistic Molecular Dynamics Provide New Insights into Folding and Unfolding of Human Telomeric G-Quadruplexes. J Chem Theory Comput 2016; 12:6077-6097. [DOI: 10.1021/acs.jctc.6b00667] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Petr Stadlbauer
- Institute
of Biophysics, Academy of Sciences of the Czech Republic, Královopolská
135, 612 65 Brno, Czech Republic
- Regional
Centre of Advanced Technologies and Materials, Departments of Physical
Chemistry, Faculty of Science, Palacký University, 17. listopadu
1192/12, 771 46 Olomouc, Czech Republic
| | - Liuba Mazzanti
- Laboratoire
de Biochimie Théorique, IBPC, CNRS UPR9080, Université Sorbonne Paris Cite, Paris Diderot, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Tristan Cragnolini
- Department
of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW, U.K
| | - David J. Wales
- Department
of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Philippe Derreumaux
- Laboratoire
de Biochimie Théorique, IBPC, CNRS UPR9080, Université Sorbonne Paris Cite, Paris Diderot, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Samuela Pasquali
- Laboratoire
de Biochimie Théorique, IBPC, CNRS UPR9080, Université Sorbonne Paris Cite, Paris Diderot, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Jiří Šponer
- Institute
of Biophysics, Academy of Sciences of the Czech Republic, Královopolská
135, 612 65 Brno, Czech Republic
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67
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Valton AL, Prioleau MN. G-Quadruplexes in DNA Replication: A Problem or a Necessity? Trends Genet 2016; 32:697-706. [DOI: 10.1016/j.tig.2016.09.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/01/2016] [Indexed: 10/21/2022]
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68
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Song J, Perreault JP, Topisirovic I, Richard S. RNA G-quadruplexes and their potential regulatory roles in translation. ACTA ACUST UNITED AC 2016; 4:e1244031. [PMID: 28090421 PMCID: PMC5173311 DOI: 10.1080/21690731.2016.1244031] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 09/26/2016] [Accepted: 09/28/2016] [Indexed: 12/11/2022]
Abstract
DNA guanine (G)-rich 4-stranded helical nucleic acid structures called G-quadruplexes (G4), have been extensively studied during the last decades. However, emerging evidence reveals that 5′- and 3′-untranslated regions (5′- and 3′-UTRs) as well as open reading frames (ORFs) contain putative RNA G-quadruplexes. These stable secondary structures play key roles in telomere homeostasis and RNA metabolism including pre-mRNA splicing, polyadenylation, mRNA targeting and translation. Interestingly, multiple RNA binding proteins such as nucleolin, FMRP, DHX36, and Aven were identified to bind RNA G-quadruplexes. Moreover, accumulating reports suggest that RNA G-quadruplexes regulate translation in cap-dependent and -independent manner. Herein, we discuss potential roles of RNA G-quadruplexes and associated trans-acting factors in the regulation of mRNA translation.
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Affiliation(s)
- Jingwen Song
- Terry Fox Molecular Oncology Group and Segal Cancer Center, McGill University, Montréal, Québec, Canada; Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research, McGill University, Montréal, Québec, Canada; Department of Oncology, McGill University, Montréal, Québec, Canada; Department of Medicine, McGill University, Montréal, Québec, Canada
| | | | - Ivan Topisirovic
- Terry Fox Molecular Oncology Group and Segal Cancer Center, McGill University, Montréal, Québec, Canada; Department of Oncology, McGill University, Montréal, Québec, Canada; Department of Biochemistry, McGill University, Montréal, Québec, Canada
| | - Stéphane Richard
- Terry Fox Molecular Oncology Group and Segal Cancer Center, McGill University, Montréal, Québec, Canada; Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research, McGill University, Montréal, Québec, Canada; Department of Oncology, McGill University, Montréal, Québec, Canada; Department of Medicine, McGill University, Montréal, Québec, Canada
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69
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Identification of Pif1 helicases with novel accessory domains in various amoebae. Mol Phylogenet Evol 2016; 103:64-74. [DOI: 10.1016/j.ympev.2016.07.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 06/06/2016] [Accepted: 07/12/2016] [Indexed: 11/19/2022]
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70
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Langley AR, Gräf S, Smith JC, Krude T. Genome-wide identification and characterisation of human DNA replication origins by initiation site sequencing (ini-seq). Nucleic Acids Res 2016; 44:10230-10247. [PMID: 27587586 PMCID: PMC5137433 DOI: 10.1093/nar/gkw760] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/18/2016] [Accepted: 08/20/2016] [Indexed: 12/25/2022] Open
Abstract
Next-generation sequencing has enabled the genome-wide identification of human DNA replication origins. However, different approaches to mapping replication origins, namely (i) sequencing isolated small nascent DNA strands (SNS-seq); (ii) sequencing replication bubbles (bubble-seq) and (iii) sequencing Okazaki fragments (OK-seq), show only limited concordance. To address this controversy, we describe here an independent high-resolution origin mapping technique that we call initiation site sequencing (ini-seq). In this approach, newly replicated DNA is directly labelled with digoxigenin-dUTP near the sites of its initiation in a cell-free system. The labelled DNA is then immunoprecipitated and genomic locations are determined by DNA sequencing. Using this technique we identify >25,000 discrete origin sites at sub-kilobase resolution on the human genome, with high concordance between biological replicates. Most activated origins identified by ini-seq are found at transcriptional start sites and contain G-quadruplex (G4) motifs. They tend to cluster in early-replicating domains, providing a correlation between early replication timing and local density of activated origins. Origins identified by ini-seq show highest concordance with sites identified by SNS-seq, followed by OK-seq and bubble-seq. Furthermore, germline origins identified by positive nucleotide distribution skew jumps overlap with origins identified by ini-seq and OK-seq more frequently and more specifically than do sites identified by either SNS-seq or bubble-seq.
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Affiliation(s)
- Alexander R Langley
- Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London NW7 1AA, UK
| | - Stefan Gräf
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
- Department of Haematology, University of Cambridge, Cambridge CB2 0PT, UK
| | - James C Smith
- Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, London NW7 1AA, UK
| | - Torsten Krude
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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71
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Drillon G, Audit B, Argoul F, Arneodo A. Evidence of selection for an accessible nucleosomal array in human. BMC Genomics 2016; 17:526. [PMID: 27472913 PMCID: PMC4966569 DOI: 10.1186/s12864-016-2880-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 07/04/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Recently, a physical model of nucleosome formation based on sequence-dependent bending properties of the DNA double-helix has been used to reveal some enrichment of nucleosome-inhibiting energy barriers (NIEBs) nearby ubiquitous human "master" replication origins. Here we use this model to predict the existence of about 1.6 millions NIEBs over the 22 human autosomes. RESULTS We show that these high energy barriers of mean size 153 bp correspond to nucleosome-depleted regions (NDRs) in vitro, as expected, but also in vivo. On either side of these NIEBs, we observe, in vivo and in vitro, a similar compacted nucleosome ordering, suggesting an absence of chromatin remodeling. This nucleosomal ordering strongly correlates with oscillations of the GC content as well as with the interspecies and intraspecies mutation profiles along these regions. Comparison of these divergence rates reveals the existence of both positive and negative selections linked to nucleosome positioning around these intrinsic NDRs. Overall, these NIEBs and neighboring nucleosomes cover 37.5 % of the human genome where nucleosome occupancy is stably encoded in the DNA sequence. These 1 kb-sized regions of intrinsic nucleosome positioning are equally found in GC-rich and GC-poor isochores, in early and late replicating regions, in intergenic and genic regions but not at gene promoters. CONCLUSION The source of selection pressure on the NIEBs has yet to be resolved in future work. One possible scenario is that these widely distributed chromatin patterns have been selected in human to impair the condensation of the nucleosomal array into the 30 nm chromatin fiber, so as to facilitate the epigenetic regulation of nuclear functions in a cell-type-specific manner.
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Affiliation(s)
- Guénola Drillon
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
| | - Benjamin Audit
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
| | - Françoise Argoul
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
- LOMA, Université de Bordeaux, CNRS, UMR 5798, 51 Cours de le Libération, Talence, F-33405 France
| | - Alain Arneodo
- Univ Lyon, Ens de Lyon, Univ Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, Lyon, F-69342 France
- LOMA, Université de Bordeaux, CNRS, UMR 5798, 51 Cours de le Libération, Talence, F-33405 France
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72
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Lombraña R, Álvarez A, Fernández-Justel JM, Almeida R, Poza-Carrión C, Gomes F, Calzada A, Requena JM, Gómez M. Transcriptionally Driven DNA Replication Program of the Human Parasite Leishmania major. Cell Rep 2016; 16:1774-1786. [PMID: 27477279 DOI: 10.1016/j.celrep.2016.07.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/26/2016] [Accepted: 07/01/2016] [Indexed: 01/04/2023] Open
Abstract
Faithful inheritance of eukaryotic genomes requires the orchestrated activation of multiple DNA replication origins (ORIs). Although origin firing is mechanistically conserved, how origins are specified and selected for activation varies across different model systems. Here, we provide a complete analysis of the nucleosomal landscape and replication program of the human parasite Leishmania major, building on a better evolutionary understanding of replication organization in Eukarya. We found that active transcription is a driving force for the nucleosomal organization of the L. major genome and that both the spatial and the temporal program of DNA replication can be explained as associated to RNA polymerase kinetics. This simple scenario likely provides flexibility and robustness to deal with the environmental changes that impose alterations in the genetic programs during parasitic life cycle stages. Our findings also suggest that coupling replication initiation to transcription elongation could be an ancient solution used by eukaryotic cells for origin maintenance.
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Affiliation(s)
- Rodrigo Lombraña
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Alba Álvarez
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
| | - José Miguel Fernández-Justel
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Ricardo Almeida
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
| | - César Poza-Carrión
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Fábia Gomes
- Centro Nacional de Biotecnología (CSIC), Darwin 3, 28049 Madrid, Spain
| | - Arturo Calzada
- Centro Nacional de Biotecnología (CSIC), Darwin 3, 28049 Madrid, Spain
| | - José María Requena
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain
| | - María Gómez
- Functional Organization of the Genome Group, Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Nicolás Cabrera 1, 28049 Madrid, Spain.
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73
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Zhang B, Wu WQ, Liu NN, Duan XL, Li M, Dou SX, Hou XM, Xi XG. G-quadruplex and G-rich sequence stimulate Pif1p-catalyzed downstream duplex DNA unwinding through reducing waiting time at ss/dsDNA junction. Nucleic Acids Res 2016; 44:8385-94. [PMID: 27471032 PMCID: PMC5041479 DOI: 10.1093/nar/gkw669] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/19/2016] [Indexed: 01/04/2023] Open
Abstract
Alternative DNA structures that deviate from B-form double-stranded DNA such as G-quadruplex (G4) DNA can be formed by G-rich sequences that are widely distributed throughout the human genome. We have previously shown that Pif1p not only unfolds G4, but also unwinds the downstream duplex DNA in a G4-stimulated manner. In the present study, we further characterized the G4-stimulated duplex DNA unwinding phenomenon by means of single-molecule fluorescence resonance energy transfer. It was found that Pif1p did not unwind the partial duplex DNA immediately after unfolding the upstream G4 structure, but rather, it would dwell at the ss/dsDNA junction with a 'waiting time'. Further studies revealed that the waiting time was in fact related to a protein dimerization process that was sensitive to ssDNA sequence and would become rapid if the sequence is G-rich. Furthermore, we identified that the G-rich sequence, as the G4 structure, equally stimulates duplex DNA unwinding. The present work sheds new light on the molecular mechanism by which G4-unwinding helicase Pif1p resolves physiological G4/duplex DNA structures in cells.
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Affiliation(s)
- Bo Zhang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Wen-Qiang Wu
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Na-Nv Liu
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xiao-Lei Duan
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Ming Li
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shuo-Xing Dou
- Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xi-Miao Hou
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xu-Guang Xi
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, Centre National de la Recherche Scientifique, 61 Avenue du Président Wilson, 94235 Cachan, France
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74
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The Histone Variant H3.3 Is Enriched at Drosophila Amplicon Origins but Does Not Mark Them for Activation. G3-GENES GENOMES GENETICS 2016; 6:1661-71. [PMID: 27172191 PMCID: PMC4889662 DOI: 10.1534/g3.116.028068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Eukaryotic DNA replication begins from multiple origins. The origin recognition complex (ORC) binds origin DNA and scaffolds assembly of a prereplicative complex (pre-RC), which is subsequently activated to initiate DNA replication. In multicellular eukaryotes, origins do not share a strict DNA consensus sequence, and their activity changes in concert with chromatin status during development, but mechanisms are ill-defined. Previous genome-wide analyses in Drosophila and other organisms have revealed a correlation between ORC binding sites and the histone variant H3.3. This correlation suggests that H3.3 may designate origin sites, but this idea has remained untested. To address this question, we examined the enrichment and function of H3.3 at the origins responsible for developmental gene amplification in the somatic follicle cells of the Drosophila ovary. We found that H3.3 is abundant at these amplicon origins. H3.3 levels remained high when replication initiation was blocked, indicating that H3.3 is abundant at the origins before activation of the pre-RC. H3.3 was also enriched at the origins during early oogenesis, raising the possibility that H3.3 bookmarks sites for later amplification. However, flies null mutant for both of the H3.3 genes in Drosophila did not have overt defects in developmental gene amplification or genomic replication, suggesting that H3.3 is not essential for the assembly or activation of the pre-RC at origins. Instead, our results imply that the correlation between H3.3 and ORC sites reflects other chromatin attributes that are important for origin function.
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75
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Smith OK, Kim R, Fu H, Martin MM, Lin CM, Utani K, Zhang Y, Marks AB, Lalande M, Chamberlain S, Libbrecht MW, Bouhassira EE, Ryan MC, Noble WS, Aladjem MI. Distinct epigenetic features of differentiation-regulated replication origins. Epigenetics Chromatin 2016; 9:18. [PMID: 27168766 PMCID: PMC4862150 DOI: 10.1186/s13072-016-0067-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 04/25/2016] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Eukaryotic genome duplication starts at discrete sequences (replication origins) that coordinate cell cycle progression, ensure genomic stability and modulate gene expression. Origins share some sequence features, but their activity also responds to changes in transcription and cellular differentiation status. RESULTS To identify chromatin states and histone modifications that locally mark replication origins, we profiled origin distributions in eight human cell lines representing embryonic and differentiated cell types. Consistent with a role of chromatin structure in determining origin activity, we found that cancer and non-cancer cells of similar lineages exhibited highly similar replication origin distributions. Surprisingly, our study revealed that DNase hypersensitivity, which often correlates with early replication at large-scale chromatin domains, did not emerge as a strong local determinant of origin activity. Instead, we found that two distinct sets of chromatin modifications exhibited strong local associations with two discrete groups of replication origins. The first origin group consisted of about 40,000 regions that actively initiated replication in all cell types and preferentially colocalized with unmethylated CpGs and with the euchromatin markers, H3K4me3 and H3K9Ac. The second group included origins that were consistently active in cells of a single type or lineage and preferentially colocalized with the heterochromatin marker, H3K9me3. Shared origins replicated throughout the S-phase of the cell cycle, whereas cell-type-specific origins preferentially replicated during late S-phase. CONCLUSIONS These observations are in line with the hypothesis that differentiation-associated changes in chromatin and gene expression affect the activation of specific replication origins.
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Affiliation(s)
- Owen K. Smith
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - RyanGuk Kim
- />In Silico Solutions, Falls Church, VA 22033 USA
| | - Haiqing Fu
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Melvenia M. Martin
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Chii Mei Lin
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Koichi Utani
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Ya Zhang
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Anna B. Marks
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
| | - Marc Lalande
- />Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06032 USA
| | - Stormy Chamberlain
- />Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06032 USA
| | - Maxwell W. Libbrecht
- />Department of Computer Science and Engineering, University of Washington, Seattle, WA 98195 USA
| | - Eric E. Bouhassira
- />Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | | | - William S. Noble
- />Department of Computer Science and Engineering, University of Washington, Seattle, WA 98195 USA
- />Department of Genome Sciences, University of Washington, Seattle, WA 98195 USA
| | - Mirit I. Aladjem
- />DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 USA
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76
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Foti R, Gnan S, Cornacchia D, Dileep V, Bulut-Karslioglu A, Diehl S, Buness A, Klein FA, Huber W, Johnstone E, Loos R, Bertone P, Gilbert DM, Manke T, Jenuwein T, Buonomo SCB. Nuclear Architecture Organized by Rif1 Underpins the Replication-Timing Program. Mol Cell 2016; 61:260-73. [PMID: 26725008 PMCID: PMC4724237 DOI: 10.1016/j.molcel.2015.12.001] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/22/2015] [Accepted: 11/13/2015] [Indexed: 02/08/2023]
Abstract
DNA replication is temporally and spatially organized in all eukaryotes, yet the molecular control and biological function of the replication-timing program are unclear. Rif1 is required for normal genome-wide regulation of replication timing, but its molecular function is poorly understood. Here we show that in mouse embryonic stem cells, Rif1 coats late-replicating domains and, with Lamin B1, identifies most of the late-replicating genome. Rif1 is an essential determinant of replication timing of non-Lamin B1-bound late domains. We further demonstrate that Rif1 defines and restricts the interactions between replication-timing domains during the G1 phase, thereby revealing a function of Rif1 as organizer of nuclear architecture. Rif1 loss affects both number and replication-timing specificity of the interactions between replication-timing domains. In addition, during the S phase, Rif1 ensures that replication of interacting domains is temporally coordinated. In summary, our study identifies Rif1 as the molecular link between nuclear architecture and replication-timing establishment in mammals.
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Affiliation(s)
- Rossana Foti
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Stefano Gnan
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Daniela Cornacchia
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Vishnu Dileep
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Aydan Bulut-Karslioglu
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Sarah Diehl
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Andreas Buness
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Felix A Klein
- Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Wolfgang Huber
- Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Ewan Johnstone
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK
| | - Remco Loos
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK
| | - Paul Bertone
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK; Genome Biology and Developmental Biology Units, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Thomas Manke
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Thomas Jenuwein
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Sara C B Buonomo
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy.
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77
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Bedrat A, Lacroix L, Mergny JL. Re-evaluation of G-quadruplex propensity with G4Hunter. Nucleic Acids Res 2016; 44:1746-59. [PMID: 26792894 PMCID: PMC4770238 DOI: 10.1093/nar/gkw006] [Citation(s) in RCA: 421] [Impact Index Per Article: 52.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/03/2016] [Indexed: 01/01/2023] Open
Abstract
Critical evidence for the biological relevance of G-quadruplexes (G4) has recently been obtained in seminal studies performed in a variety of organisms. Four-stranded G-quadruplex DNA structures are promising drug targets as these non-canonical structures appear to be involved in a number of key biological processes. Given the growing interest for G4, accurate tools to predict G-quadruplex propensity of a given DNA or RNA sequence are needed. Several algorithms such as Quadparser predict quadruplex forming propensity. However, a number of studies have established that sequences that are not detected by these tools do form G4 structures (false negatives) and that other sequences predicted to form G4 structures do not (false positives). Here we report development and testing of a radically different algorithm, G4Hunter that takes into account G-richness and G-skewness of a given sequence and gives a quadruplex propensity score as output. To validate this model, we tested it on a large dataset of 392 published sequences and experimentally evaluated quadruplex forming potential of 209 sequences using a combination of biophysical methods to assess quadruplex formation in vitro. We experimentally validated the G4Hunter algorithm on a short complete genome, that of the human mitochondria (16.6 kb), because of its relatively high GC content and GC skewness as well as the biological relevance of these quadruplexes near instability hotspots. We then applied the algorithm to genomes of a number of species, including humans, allowing us to conclude that the number of sequences capable of forming stable quadruplexes (at least in vitro) in the human genome is significantly higher, by a factor of 2–10, than previously thought.
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Affiliation(s)
- Amina Bedrat
- Université de Bordeaux, ARNA Laboratory, F-33000 Bordeaux, France Inserm U1212, CNRS UMR 5320, IECB, F-33600 Pessac, France
| | - Laurent Lacroix
- CNRS-Université de Toulouse UMR5099, F-31000 Toulouse, France
| | - Jean-Louis Mergny
- Université de Bordeaux, ARNA Laboratory, F-33000 Bordeaux, France Inserm U1212, CNRS UMR 5320, IECB, F-33600 Pessac, France
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78
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Hutchins JRA, Aze A, Coulombe P, Méchali M. Characteristics of Metazoan DNA Replication Origins. DNA REPLICATION, RECOMBINATION, AND REPAIR 2016. [PMCID: PMC7120227 DOI: 10.1007/978-4-431-55873-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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79
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Cayrou C, Ballester B, Peiffer I, Fenouil R, Coulombe P, Andrau JC, van Helden J, Méchali M. The chromatin environment shapes DNA replication origin organization and defines origin classes. Genome Res 2015; 25:1873-85. [PMID: 26560631 PMCID: PMC4665008 DOI: 10.1101/gr.192799.115] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 10/14/2015] [Indexed: 12/22/2022]
Abstract
To unveil the still-elusive nature of metazoan replication origins, we identified them genome-wide and at unprecedented high-resolution in mouse ES cells. This allowed initiation sites (IS) and initiation zones (IZ) to be differentiated. We then characterized their genetic signatures and organization and integrated these data with 43 chromatin marks and factors. Our results reveal that replication origins can be grouped into three main classes with distinct organization, chromatin environment, and sequence motifs. Class 1 contains relatively isolated, low-efficiency origins that are poor in epigenetic marks and are enriched in an asymmetric AC repeat at the initiation site. Late origins are mainly found in this class. Class 2 origins are particularly rich in enhancer elements. Class 3 origins are the most efficient and are associated with open chromatin and polycomb protein-enriched regions. The presence of Origin G-rich Repeated elements (OGRE) potentially forming G-quadruplexes (G4) was confirmed at most origins. These coincide with nucleosome-depleted regions located upstream of the initiation sites, which are associated with a labile nucleosome containing H3K64ac. These data demonstrate that specific chromatin landscapes and combinations of specific signatures regulate origin localization. They explain the frequently observed links between DNA replication and transcription. They also emphasize the plasticity of metazoan replication origins and suggest that in multicellular eukaryotes, the combination of distinct genetic features and chromatin configurations act in synergy to define and adapt the origin profile.
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Affiliation(s)
| | - Benoit Ballester
- INSERM, U1090 TAGC, Marseille F-13288, France; Aix Marseille University, U1090 TAGC, Marseille F-13288, France
| | | | - Romain Fenouil
- Centre d'Immunologie de Marseille-Luminy (CIML), 13009 Marseille, France
| | | | | | - Jacques van Helden
- INSERM, U1090 TAGC, Marseille F-13288, France; Aix Marseille University, U1090 TAGC, Marseille F-13288, France
| | - Marcel Méchali
- Institute of Human Genetics, CNRS, 34396 Montpellier, France
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80
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Rif1 binds to G quadruplexes and suppresses replication over long distances. Nat Struct Mol Biol 2015; 22:889-97. [PMID: 26436827 DOI: 10.1038/nsmb.3102] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 09/03/2015] [Indexed: 12/20/2022]
Abstract
Rif1 regulates replication timing and repair of double-strand DNA breaks. Using a chromatin immunoprecipitation-sequencing method, we identified 35 high-affinity Rif1-binding sites in fission yeast chromosomes. Binding sites tended to be located near dormant origins and to contain at least two copies of a conserved motif, CNWWGTGGGGG. Base substitution within these motifs resulted in complete loss of Rif1 binding and in activation of late-firing or dormant origins located up to 50 kb away. We show that Rif1-binding sites adopt G quadruplex-like structures in vitro, in a manner dependent on the conserved sequence and on other G tracts, and that purified Rif1 preferentially binds to this structure. These results suggest that Rif1 recognizes and binds G quadruplex-like structures at selected intergenic regions, thus generating local chromatin structures that may exert long-range suppressive effects on origin firing.
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81
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Stadlbauer P, Kührová P, Banáš P, Koča J, Bussi G, Trantírek L, Otyepka M, Šponer J. Hairpins participating in folding of human telomeric sequence quadruplexes studied by standard and T-REMD simulations. Nucleic Acids Res 2015; 43:9626-44. [PMID: 26433223 PMCID: PMC4787745 DOI: 10.1093/nar/gkv994] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 09/22/2015] [Indexed: 11/13/2022] Open
Abstract
DNA G-hairpins are potential key structures participating in folding of human telomeric guanine quadruplexes (GQ). We examined their properties by standard MD simulations starting from the folded state and long T-REMD starting from the unfolded state, accumulating ∼130 μs of atomistic simulations. Antiparallel G-hairpins should spontaneously form in all stages of the folding to support lateral and diagonal loops, with sub-μs scale rearrangements between them. We found no clear predisposition for direct folding into specific GQ topologies with specific syn/anti patterns. Our key prediction stemming from the T-REMD is that an ideal unfolded ensemble of the full GQ sequence populates all 4096 syn/anti combinations of its four G-stretches. The simulations can propose idealized folding pathways but we explain that such few-state pathways may be misleading. In the context of the available experimental data, the simulations strongly suggest that the GQ folding could be best understood by the kinetic partitioning mechanism with a set of deep competing minima on the folding landscape, with only a small fraction of molecules directly folding to the native fold. The landscape should further include non-specific collapse processes where the molecules move via diffusion and consecutive random rare transitions, which could, e.g. structure the propeller loops.
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Affiliation(s)
- Petr Stadlbauer
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, Czech Republic
| | - Petra Kührová
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Pavel Banáš
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Jaroslav Koča
- CEITEC - Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic National Center for Biomolecular Research, Faculty of Science, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, 34136 Trieste, Italy
| | - Lukáš Trantírek
- CEITEC - Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46 Olomouc, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, Czech Republic CEITEC - Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic
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82
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Zamiri B, Mirceta M, Bomsztyk K, Macgregor RB, Pearson CE. Quadruplex formation by both G-rich and C-rich DNA strands of the C9orf72 (GGGGCC)8•(GGCCCC)8 repeat: effect of CpG methylation. Nucleic Acids Res 2015; 43:10055-64. [PMID: 26432832 PMCID: PMC4787773 DOI: 10.1093/nar/gkv1008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/22/2015] [Indexed: 12/13/2022] Open
Abstract
Unusual DNA/RNA structures of the C9orf72 repeat may participate in repeat expansions or pathogenesis of amyotrophic lateral sclerosis and frontotemporal dementia. Expanded repeats are CpG methylated with unknown consequences. Typically, quadruplex structures form by G-rich but not complementary C-rich strands. Using CD, UV and electrophoresis, we characterized the structures formed by (GGGGCC)8 and (GGCCCC)8 strands with and without 5-methylcytosine (5mCpG) or 5-hydroxymethylcytosine (5hmCpG) methylation. All strands formed heterogenous mixtures of structures, with features of quadruplexes (at pH 7.5, in K(+), Na(+) or Li(+)), but no feature typical of i-motifs. C-rich strands formed quadruplexes, likely stabilized by G•C•G•C-tetrads and C•C•C•C-tetrads. Unlike G•G•G•G-tetrads, some G•C•G•C-tetrad conformations do not require the N7-Guanine position, hence C9orf72 quadruplexes still formed when N7-deazaGuanine replace all Guanines. 5mCpG and 5hmCpG increased and decreased the thermal stability of these structures. hnRNPK, through band-shift analysis, bound C-rich but not G-rich strands, with a binding preference of unmethylated > 5hmCpG > 5mCpG, where methylated DNA-protein complexes were retained in the wells, distinct from unmethylated complexes. Our findings suggest that for C-rich sequences interspersed with G-residues, one must consider quadruplex formation and that methylation of quadruplexes may affect epigenetic processes.
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Affiliation(s)
- Bita Zamiri
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - Mila Mirceta
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada Program of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A1, Canada
| | - Karol Bomsztyk
- UW Medicine South Lake Union, University of Washington, Seattle WA 98109, USA
| | - Robert B Macgregor
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada Program of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A1, Canada
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83
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Abstract
DNA replication begins with the assembly of pre-replication complexes (pre-RCs) at thousands of DNA replication origins during the G1 phase of the cell cycle. At the G1-S-phase transition, pre-RCs are converted into pre-initiation complexes, in which the replicative helicase is activated, leading to DNA unwinding and initiation of DNA synthesis. However, only a subset of origins are activated during any S phase. Recent insights into the mechanisms underlying this choice reveal how flexibility in origin usage and temporal activation are linked to chromosome structure and organization, cell growth and differentiation, and replication stress.
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84
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Liu J, Zimmer K, Rusch DB, Paranjape N, Podicheti R, Tang H, Calvi BR. DNA sequence templates adjacent nucleosome and ORC sites at gene amplification origins in Drosophila. Nucleic Acids Res 2015; 43:8746-61. [PMID: 26227968 PMCID: PMC4605296 DOI: 10.1093/nar/gkv766] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/16/2015] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic origins of DNA replication are bound by the origin recognition complex (ORC), which scaffolds assembly of a pre-replicative complex (pre-RC) that is then activated to initiate replication. Both pre-RC assembly and activation are strongly influenced by developmental changes to the epigenome, but molecular mechanisms remain incompletely defined. We have been examining the activation of origins responsible for developmental gene amplification in Drosophila. At a specific time in oogenesis, somatic follicle cells transition from genomic replication to a locus-specific replication from six amplicon origins. Previous evidence indicated that these amplicon origins are activated by nucleosome acetylation, but how this affects origin chromatin is unknown. Here, we examine nucleosome position in follicle cells using micrococcal nuclease digestion with Ilumina sequencing. The results indicate that ORC binding sites and other essential origin sequences are nucleosome-depleted regions (NDRs). Nucleosome position at the amplicons was highly similar among developmental stages during which ORC is or is not bound, indicating that being an NDR is not sufficient to specify ORC binding. Importantly, the data suggest that nucleosomes and ORC have opposite preferences for DNA sequence and structure. We propose that nucleosome hyperacetylation promotes pre-RC assembly onto adjacent DNA sequences that are disfavored by nucleosomes but favored by ORC.
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Affiliation(s)
- Jun Liu
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Kurt Zimmer
- School of Informatics and Computing, Indiana University, Bloomington, IN 47405, USA
| | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN 47405, USA
| | - Neha Paranjape
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Ram Podicheti
- School of Informatics and Computing, Indiana University, Bloomington, IN 47405, USA Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN 47405, USA
| | - Haixu Tang
- School of Informatics and Computing, Indiana University, Bloomington, IN 47405, USA
| | - Brian R Calvi
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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85
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Sequeira-Mendes J, Gutierrez C. Links between genome replication and chromatin landscapes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:38-51. [PMID: 25847096 DOI: 10.1111/tpj.12847] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 03/27/2015] [Accepted: 04/01/2015] [Indexed: 05/07/2023]
Abstract
Post-embryonic organogenesis in plants requires the continuous production of cells in the organ primordia, their expansion and a coordinated exit to differentiation. Genome replication is one of the most important processes that occur during the cell cycle, as the maintenance of genomic integrity is of primary relevance for development. As it is chromatin that must be duplicated, a strict coordination occurs between DNA replication, the deposition of new histones, and the introduction of histone modifications and variants. In turn, the chromatin landscape affects several stages during genome replication. Thus, chromatin accessibility is crucial for the initial stages and to specify the location of DNA replication origins with different chromatin signatures. The chromatin landscape also determines the timing of activation during the S phase. Genome replication must occur fully, but only once during each cell cycle. The re-replication avoidance mechanisms rely primarily on restricting the availability of certain replication factors; however, the presence of specific histone modifications are also revealed as contributing to the mechanisms that avoid re-replication, in particular for heterochromatin replication. We provide here an update of genome replication mostly focused on data from Arabidopsis, and the advances that genomic approaches are likely to provide in the coming years. The data available, both in plants and animals, point to the relevance of the chromatin landscape in genome replication, and require a critical evaluation of the existing views about the nature of replication origins, the mechanisms of origin specification and the relevance of epigenetic modifications for genome replication.
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Affiliation(s)
- Joana Sequeira-Mendes
- Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049, Madrid, Spain
| | - Crisanto Gutierrez
- Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, Cantoblanco, 28049, Madrid, Spain
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86
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Sherstyuk VV, Shevchenko AI, Zakian SM. Mapping of Replication Origins in the X Inactivation Center of Vole Microtus levis Reveals Extended Replication Initiation Zone. PLoS One 2015; 10:e0128497. [PMID: 26038842 PMCID: PMC4454516 DOI: 10.1371/journal.pone.0128497] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 04/27/2015] [Indexed: 11/29/2022] Open
Abstract
DNA replication initiates at specific positions termed replication origins. Genome-wide studies of human replication origins have shown that origins are organized into replication initiation zones. However, only few replication initiation zones have been described so far. Moreover, few origins were mapped in other mammalian species besides human and mouse. Here we analyzed pattern of short nascent strands in the X inactivation center (XIC) of vole Microtus levis in fibroblasts, trophoblast stem cells, and extraembryonic endoderm stem cells and confirmed origins locations by ChIP approach. We found that replication could be initiated in a significant part of XIC. We also analyzed state of XIC chromatin in these cell types. We compared origin localization in the mouse and vole XIC. Interestingly, origins associated with gene promoters are conserved in these species. The data obtained allow us to suggest that the X inactivation center of M. levis is one extended replication initiation zone.
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Affiliation(s)
- Vladimir V. Sherstyuk
- Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia
- State Research Institute of Circulation Pathology, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia
| | - Alexander I. Shevchenko
- Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia
- State Research Institute of Circulation Pathology, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia
| | - Suren M. Zakian
- Institute of Cytology and Genetics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia
- State Research Institute of Circulation Pathology, Novosibirsk, Russia
- Institute of Chemical Biology and Fundamental Medicine, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
- * E-mail:
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87
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Bartholdy B, Mukhopadhyay R, Lajugie J, Aladjem MI, Bouhassira EE. Allele-specific analysis of DNA replication origins in mammalian cells. Nat Commun 2015; 6:7051. [PMID: 25987481 PMCID: PMC4479011 DOI: 10.1038/ncomms8051] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/26/2015] [Indexed: 01/01/2023] Open
Abstract
The mechanisms that control the location and timing of firing of replication origins are poorly understood. Using a novel functional genomic approach based on the analysis of SNPs and indels in phased human genomes, we observe that replication asynchrony is associated with small cumulative variations in the initiation efficiency of multiple origins between the chromosome homologues, rather than with the activation of dormant origins. Allele-specific measurements demonstrate that the presence of G-quadruplex-forming sequences does not correlate with the efficiency of initiation. Sequence analysis reveals that the origins are highly enriched in sequences with profoundly asymmetric G/C and A/T nucleotide distributions and are almost completely depleted of antiparallel triplex-forming sequences. We therefore propose that although G4-forming sequences are abundant in replication origins, an asymmetry in nucleotide distribution, which increases the propensity of origins to unwind and adopt non-B DNA structure, rather than the ability to form G4, is directly associated with origin activity.
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Affiliation(s)
- Boris Bartholdy
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
| | - Rituparna Mukhopadhyay
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
| | - Julien Lajugie
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
| | - Mirit I. Aladjem
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, 37 Convent Drive, Bethesda, Maryland 20892, USA
| | - Eric E. Bouhassira
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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88
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Eddy S, Maddukuri L, Ketkar A, Zafar MK, Henninger EE, Pursell ZF, Eoff RL. Evidence for the kinetic partitioning of polymerase activity on G-quadruplex DNA. Biochemistry 2015; 54:3218-30. [PMID: 25903680 DOI: 10.1021/acs.biochem.5b00060] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We have investigated the action of the human DNA polymerase ε (hpol ε) and η (hpol η) catalytic cores on G-quadruplex (G4) DNA substrates derived from the promoter of the c-MYC proto-oncogene. The translesion enzyme hpol η exhibits a 6.2-fold preference for binding to G4 DNA over non-G4 DNA, while hpol ε binds both G4 and non-G4 substrates with nearly equal affinity. Kinetic analysis of single-nucleotide insertion by hpol η reveals that it is able to maintain >25% activity on G4 substrates compared to non-G4 DNA substrates, even when the primer template junction is positioned directly adjacent to G22 (the first tetrad-associated guanine in the c-MYC G4 motif). Surprisingly, hpol η fidelity increases ~15-fold when copying G22. By way of comparison, hpol ε retains ~4% activity and has a 33-fold decrease in fidelity when copying G22. The fidelity of hpol η is ~100-fold greater than that of hpol ε when comparing the misinsertion frequencies of the two enzymes opposite a tetrad-associated guanine. The kinetic differences observed for the B- and Y-family pols on G4 DNA support a model in which a simple kinetic switch between replicative and TLS pols could help govern fork progress during G4 DNA replication.
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Affiliation(s)
- Sarah Eddy
- †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Leena Maddukuri
- †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Amit Ketkar
- †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Maroof K Zafar
- †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
| | - Erin E Henninger
- ‡Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, Louisiana 70112, United States
| | - Zachary F Pursell
- ‡Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, Louisiana 70112, United States
| | - Robert L Eoff
- †Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, United States
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89
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Lombraña R, Almeida R, Álvarez A, Gómez M. R-loops and initiation of DNA replication in human cells: a missing link? Front Genet 2015; 6:158. [PMID: 25972891 PMCID: PMC4412123 DOI: 10.3389/fgene.2015.00158] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 04/08/2015] [Indexed: 11/13/2022] Open
Abstract
The unanticipated widespread occurrence of stable hybrid DNA/RNA structures (R-loops) in human cells and the increasing evidence of their involvement in several human malignancies have invigorated the research on R-loop biology in recent years. Here we propose that physiological R-loop formation at CpG island promoters can contribute to DNA replication origin specification at these regions, the most efficient replication initiation sites in mammalian cells. Quite likely, this occurs by the strand-displacement reaction activating the formation of G-quadruplex structures that target the origin recognition complex (ORC) in the single-stranded conformation. In agreement with this, we found that R-loops co-localize with the ORC within the same CpG island region in a significant fraction of these efficient replication origins, precisely at the position displaying the highest density of G4 motifs. This scenario builds on the connection between transcription and replication in human cells and suggests that R-loop dysregulation at CpG island promoter-origins might contribute to the phenotype of DNA replication abnormalities and loss of genome integrity detected in cancer cells.
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Affiliation(s)
- Rodrigo Lombraña
- Functional Organization of the Genome Group, Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid , Madrid, Spain
| | - Ricardo Almeida
- Functional Organization of the Genome Group, Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid , Madrid, Spain
| | - Alba Álvarez
- Functional Organization of the Genome Group, Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid , Madrid, Spain
| | - María Gómez
- Functional Organization of the Genome Group, Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid , Madrid, Spain
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90
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Comoglio F, Schlumpf T, Schmid V, Rohs R, Beisel C, Paro R. High-resolution profiling of Drosophila replication start sites reveals a DNA shape and chromatin signature of metazoan origins. Cell Rep 2015; 11:821-34. [PMID: 25921534 DOI: 10.1016/j.celrep.2015.03.070] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/09/2015] [Accepted: 03/29/2015] [Indexed: 11/16/2022] Open
Abstract
At every cell cycle, faithful inheritance of metazoan genomes requires the concerted activation of thousands of DNA replication origins. However, the genetic and chromatin features defining metazoan replication start sites remain largely unknown. Here, we delineate the origin repertoire of the Drosophila genome at high resolution. We address the role of origin-proximal G-quadruplexes and suggest that they transiently stall replication forks in vivo. We dissect the chromatin configuration of replication origins and identify a rich spatial organization of chromatin features at initiation sites. DNA shape and chromatin configurations, not strict sequence motifs, mark and predict origins in higher eukaryotes. We further examine the link between transcription and origin firing and reveal that modulation of origin activity across cell types is intimately linked to cell-type-specific transcriptional programs. Our study unravels conserved origin features and provides unique insights into the relationship among DNA topology, chromatin, transcription, and replication initiation across metazoa.
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Affiliation(s)
- Federico Comoglio
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Tommy Schlumpf
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Virginia Schmid
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Remo Rohs
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Christian Beisel
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Renato Paro
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland; Faculty of Science, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.
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91
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Urban JM, Foulk MS, Casella C, Gerbi SA. The hunt for origins of DNA replication in multicellular eukaryotes. F1000PRIME REPORTS 2015; 7:30. [PMID: 25926981 PMCID: PMC4371235 DOI: 10.12703/p7-30] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Origins of DNA replication (ORIs) occur at defined regions in the genome. Although DNA sequence defines the position of ORIs in budding yeast, the factors for ORI specification remain elusive in metazoa. Several methods have been used recently to map ORIs in metazoan genomes with the hope that features for ORI specification might emerge. These methods are reviewed here with analysis of their advantages and shortcomings. The various factors that may influence ORI selection for initiation of DNA replication are discussed.
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Affiliation(s)
- John M. Urban
- Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown UniversitySidney Frank Hall, 185 Meeting Street, Providence, RI 02912USA
| | - Michael S. Foulk
- Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown UniversitySidney Frank Hall, 185 Meeting Street, Providence, RI 02912USA
- Department of Biology, Mercyhurst University501 East 38th Street, Erie, PA 16546USA
| | - Cinzia Casella
- Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown UniversitySidney Frank Hall, 185 Meeting Street, Providence, RI 02912USA
- Institute for Molecular Medicine, University of Southern DenmarkJB Winsloews Vej 25, 5000 Odense CDenmark
| | - Susan A. Gerbi
- Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Brown UniversitySidney Frank Hall, 185 Meeting Street, Providence, RI 02912USA
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92
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Foulk MS, Urban JM, Casella C, Gerbi SA. Characterizing and controlling intrinsic biases of lambda exonuclease in nascent strand sequencing reveals phasing between nucleosomes and G-quadruplex motifs around a subset of human replication origins. Genome Res 2015; 25:725-35. [PMID: 25695952 PMCID: PMC4417120 DOI: 10.1101/gr.183848.114] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 02/18/2015] [Indexed: 01/02/2023]
Abstract
Nascent strand sequencing (NS-seq) is used to discover DNA replication origins genome-wide, allowing identification of features for their specification. NS-seq depends on the ability of lambda exonuclease (λ-exo) to efficiently digest parental DNA while leaving RNA-primer protected nascent strands intact. We used genomics and biochemical approaches to determine if λ-exo digests all parental DNA sequences equally. We report that λ-exo does not efficiently digest G-quadruplex (G4) structures in a plasmid. Moreover, λ-exo digestion of nonreplicating genomic DNA (LexoG0) enriches GC-rich DNA and G4 motifs genome-wide. We used LexoG0 data to control for nascent strand–independent λ-exo biases in NS-seq and validated this approach at the rDNA locus. The λ-exo–controlled NS-seq peaks are not GC-rich, and only 35.5% overlap with 6.8% of all G4s, suggesting that G4s are not general determinants for origin specification but may play a role for a subset. Interestingly, we observed a periodic spacing of G4 motifs and nucleosomes around the peak summits, suggesting that G4s may position nucleosomes at this subset of origins. Finally, we demonstrate that use of Na+ instead of K+ in the λ-exo digestion buffer reduced the effect of G4s on λ-exo digestion and discuss ways to increase both the sensitivity and specificity of NS-seq.
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Affiliation(s)
- Michael S Foulk
- Brown University Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Providence, Rhode Island 02912, USA
| | - John M Urban
- Brown University Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Providence, Rhode Island 02912, USA
| | - Cinzia Casella
- Brown University Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Providence, Rhode Island 02912, USA
| | - Susan A Gerbi
- Brown University Division of Biology and Medicine, Department of Molecular Biology, Cell Biology and Biochemistry, Providence, Rhode Island 02912, USA
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93
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Drillon G, Audit B, Argoul F, Arneodo A. Ubiquitous human 'master' origins of replication are encoded in the DNA sequence via a local enrichment in nucleosome excluding energy barriers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:064102. [PMID: 25563930 DOI: 10.1088/0953-8984/27/6/064102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
As the elementary building block of eukaryotic chromatin, the nucleosome is at the heart of the compromise between the necessity of compacting DNA in the cell nucleus and the required accessibility to regulatory proteins. The recent availability of genome-wide experimental maps of nucleosome positions for many different organisms and cell types has provided an unprecedented opportunity to elucidate to what extent the DNA sequence conditions the primary structure of chromatin and in turn participates in the chromatin-mediated regulation of nuclear functions, such as gene expression and DNA replication. In this study, we use in vivo and in vitro genome-wide nucleosome occupancy data together with the set of nucleosome-free regions (NFRs) predicted by a physical model of nucleosome formation based on sequence-dependent bending properties of the DNA double-helix, to investigate the role of intrinsic nucleosome occupancy in the regulation of the replication spatio-temporal programme in human. We focus our analysis on the so-called replication U/N-domains that were shown to cover about half of the human genome in the germline (skew-N domains) as well as in embryonic stem cells, somatic and HeLa cells (mean replication timing U-domains). The 'master' origins of replication (MaOris) that border these megabase-sized U/N-domains were found to be specified by a few hundred kb wide regions that are hyper-sensitive to DNase I cleavage, hypomethylated, and enriched in epigenetic marks involved in transcription regulation, the hallmarks of localized open chromatin structures. Here we show that replication U/N-domain borders that are conserved in all considered cell lines have an environment highly enriched in nucleosome-excluding-energy barriers, suggesting that these ubiquitous MaOris have been selected during evolution. In contrast, MaOris that are cell-type-specific are mainly regulated epigenetically and are no longer favoured by a local abundance of intrinsic NFRs encoded in the DNA sequence. At the smaller few hundred bp scale of gene promoters, CpG-rich promoters of housekeeping genes found nearby ubiquitous MaOris as well as CpG-poor promoters of tissue-specific genes found nearby cell-type-specific MaOris, both correspond to in vivo NFRs that are not coded as nucleosome-excluding-energy barriers. Whereas the former promoters are likely to correspond to high occupancy transcription factor binding regions, the latter are an illustration that gene regulation in human is typically cell-type-specific.
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Affiliation(s)
- Guénola Drillon
- Université de Lyon, F-69000 Lyon, France. Laboratoire de Physique, CNRS UMR 5672, École Normale Supérieure de Lyon, F-69007 Lyon, France
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94
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Wickramasinghe CM, Arzouk H, Frey A, Maiter A, Sale JE. Contributions of the specialised DNA polymerases to replication of structured DNA. DNA Repair (Amst) 2015; 29:83-90. [PMID: 25704659 DOI: 10.1016/j.dnarep.2015.01.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 01/16/2015] [Indexed: 01/06/2023]
Abstract
It is becoming increasingly clear that processive DNA replication is threatened not only by DNA damage but also by secondary structures that can form in the DNA template. Failure to resolve these structures promptly leads to both genetic instability, for instance DNA breaks and rearrangements, and to epigenetic instability, in which inaccurate propagation of the parental chromatin state leads to unscheduled changes in gene expression. Multiple overlapping mechanisms are needed to deal with the wide range of potential DNA structural challenges to replication. This review focuses on the emerging mechanisms by which specialised DNA polymerases, best known for their role in the replication of damaged DNA, contribute to the replication of undamaged but structured DNA, particularly G quadruplexes.
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Affiliation(s)
| | - Hayat Arzouk
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Alexander Frey
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Ahmed Maiter
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Julian E Sale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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95
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Embryonic stem cell specific "master" replication origins at the heart of the loss of pluripotency. PLoS Comput Biol 2015; 11:e1003969. [PMID: 25658386 PMCID: PMC4319821 DOI: 10.1371/journal.pcbi.1003969] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 10/06/2014] [Indexed: 11/29/2022] Open
Abstract
Epigenetic regulation of the replication program during mammalian cell differentiation remains poorly understood. We performed an integrative analysis of eleven genome-wide epigenetic profiles at 100 kb resolution of Mean Replication Timing (MRT) data in six human cell lines. Compared to the organization in four chromatin states shared by the five somatic cell lines, embryonic stem cell (ESC) line H1 displays (i) a gene-poor but highly dynamic chromatin state (EC4) associated to histone variant H2AZ rather than a HP1-associated heterochromatin state (C4) and (ii) a mid-S accessible chromatin state with bivalent gene marks instead of a polycomb-repressed heterochromatin state. Plastic MRT regions (≲ 20% of the genome) are predominantly localized at the borders of U-shaped timing domains. Whereas somatic-specific U-domain borders are gene-dense GC-rich regions, 31.6% of H1-specific U-domain borders are early EC4 regions enriched in pluripotency transcription factors NANOG and OCT4 despite being GC poor and gene deserts. Silencing of these ESC-specific “master” replication initiation zones during differentiation corresponds to a loss of H2AZ and an enrichment in H3K9me3 mark characteristic of late replicating C4 heterochromatin. These results shed a new light on the epigenetically regulated global chromatin reorganization that underlies the loss of pluripotency and lineage commitment. During development, embryonic stem cell (ESC) enter a program of cell differentiation eventually leading to all the necessary differentiated cell types. Understanding the mechanisms responsible for the underlying modifications of the gene expression program is of fundamental importance, as it will likely have strong impact on the development of regenerative medicine. We show that besides some epigenetic regulation, ubiquitous master replication origins at replication timing U-domain borders shared by 6 human cell types are transcriptionally active open chromatin regions specified by a local enrichment in nucleosome free regions encoded in the DNA sequence suggesting that they have been selected during evolution. In contrast, ESC specific master replication origins bear a unique epigenetic signature (enrichment in CTCF, H2AZ, NANOG, OCT4, …) likely contributing to maintain ESC chromatin in a highly dynamic and accessible state that is refractory to polycomb and HP1 heterochromatin spreading. These ESC specific master origins thus appear as key genomic regions where epigenetic control of chromatin organization is at play to maintain pluripotency of stem cell lineages and to guide lineage commitment to somatic cell types.
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96
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Duan XL, Liu NN, Yang YT, Li HH, Li M, Dou SX, Xi XG. G-quadruplexes significantly stimulate Pif1 helicase-catalyzed duplex DNA unwinding. J Biol Chem 2015; 290:7722-35. [PMID: 25627683 DOI: 10.1074/jbc.m114.628008] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The evolutionarily conserved G-quadruplexes (G4s) are faithfully inherited and serve a variety of cellular functions such as telomere maintenance, gene regulation, DNA replication initiation, and epigenetic regulation. Different from the Watson-Crick base-pairing found in duplex DNA, G4s are formed via Hoogsteen base pairing and are very stable and compact DNA structures. Failure of untangling them in the cell impedes DNA-based transactions and leads to genome instability. Cells have evolved highly specific helicases to resolve G4 structures. We used a recombinant nuclear form of Saccharomyces cerevisiae Pif1 to characterize Pif1-mediated DNA unwinding with a substrate mimicking an ongoing lagging strand synthesis stalled by G4s, which resembles a replication origin and a G4-structured flap in Okazaki fragment maturation. We find that the presence of G4 may greatly stimulate the Pif1 helicase to unwind duplex DNA. Further studies reveal that this stimulation results from G4-enhanced Pif1 dimerization, which is required for duplex DNA unwinding. This finding provides new insights into the properties and functions of G4s. We discuss the observed activation phenomenon in relation to the possible regulatory role of G4s in the rapid rescue of the stalled lagging strand synthesis by helping the replicator recognize and activate the replication origin as well as by quickly removing the G4-structured flap during Okazaki fragment maturation.
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Affiliation(s)
- Xiao-Lei Duan
- From the College of Life Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China
| | - Na-Nv Liu
- From the College of Life Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China
| | - Yan-Tao Yang
- From the College of Life Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China
| | - Hai-Hong Li
- From the College of Life Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China
| | - Ming Li
- the CAS Key Laboratory of Soft Matter Physics, International Associated Laboratory of CNRS-Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and
| | - Shuo-Xing Dou
- the CAS Key Laboratory of Soft Matter Physics, International Associated Laboratory of CNRS-Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and
| | - Xu-Guang Xi
- From the College of Life Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China, the Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure de Cachan, CNRS, 61 Avenue du Président Wilson, 94235 Cachan, France
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97
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Dellino GI, Pelicci PG. Next-generation sequencing and DNA replication in human cells: the future has arrived. Future Oncol 2015; 10:683-93. [PMID: 24754597 DOI: 10.2217/fon.13.182] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Accurate regulation of DNA replication ensures faithful transmission of eukaryotic genomes and maintenance of genomic stability and chromatin organization. However, by itself the replication process is a threat for both DNA and chromatin integrity. This becomes particularly relevant in cancer cells, where activated oncogenes induce replication-stress, including unscheduled initiation, fork stalling and collapse and, ultimately, genomic instability. Studies addressing the relationship between (epi)genome integrity and disease have been hampered by our poor knowledge of the mechanisms regulating where and when eukaryotic replication initiates. Recently developed genome-scale methods for the analysis of DNA replication in mammals will contribute to the identification of missing links between replication, chromatin regulation and genome stability in normal and cancer cells.
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Affiliation(s)
- Gaetano Ivan Dellino
- Department of Experimental Oncology, European Institute of Oncology, 20141 Milan, Italy
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98
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Hyrien O. Peaks cloaked in the mist: the landscape of mammalian replication origins. J Cell Biol 2015; 208:147-60. [PMID: 25601401 PMCID: PMC4298691 DOI: 10.1083/jcb.201407004] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 12/16/2014] [Indexed: 12/23/2022] Open
Abstract
Replication of mammalian genomes starts at sites termed replication origins, which historically have been difficult to locate as a result of large genome sizes, limited power of genetic identification schemes, and rareness and fragility of initiation intermediates. However, origins are now mapped by the thousands using microarrays and sequencing techniques. Independent studies show modest concordance, suggesting that mammalian origins can form at any DNA sequence but are suppressed by read-through transcription or that they can overlap the 5' end or even the entire gene. These results require a critical reevaluation of whether origins form at specific DNA elements and/or epigenetic signals or require no such determinants.
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Affiliation(s)
- Olivier Hyrien
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique UMR8197 and Institut National de la Santé et de la Recherche Médicale U1024, 75005 Paris, France
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99
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Lexa M, Steflova P, Martinek T, Vorlickova M, Vyskot B, Kejnovsky E. Guanine quadruplexes are formed by specific regions of human transposable elements. BMC Genomics 2014; 15:1032. [PMID: 25431265 PMCID: PMC4407331 DOI: 10.1186/1471-2164-15-1032] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/29/2014] [Indexed: 11/23/2022] Open
Abstract
Background Transposable elements form a significant proportion of eukaryotic genomes. Recently, Lexa et al. (Nucleic Acids Res 42:968-978, 2014) reported that plant long terminal repeat (LTR) retrotransposons often contain potential quadruplex sequences (PQSs) in their LTRs and experimentally confirmed their ability to adopt four-stranded DNA conformations. Results Here, we searched for PQSs in human retrotransposons and found that PQSs are specifically localized in the 3’-UTR of LINE-1 elements, in LTRs of HERV elements and are strongly accumulated in specific regions of SVA elements. Circular dichroism spectroscopy confirmed that most PQSs had adopted monomolecular or bimolecular guanine quadruplex structures. Evolutionarily young SVA elements contained more PQSs than older elements and their propensity to form quadruplex DNA was higher. Full-length L1 elements contained more PQSs than truncated elements; the highest proportion of PQSs was found inside transpositionally active L1 elements (PA2 and HS families). Conclusions Conservation of quadruplexes at specific positions of transposable elements implies their importance in their life cycle. The increasing quadruplex presence in evolutionarily young LINE-1 and SVA families makes these elements important contributors toward present genome-wide quadruplex distribution. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1032) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | - Eduard Kejnovsky
- Department of Plant Developmental Genetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic.
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100
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Li WC, Zhong ZJ, Zhu PP, Deng EZ, Ding H, Chen W, Lin H. Sequence analysis of origins of replication in the Saccharomyces cerevisiae genomes. Front Microbiol 2014; 5:574. [PMID: 25477864 PMCID: PMC4235382 DOI: 10.3389/fmicb.2014.00574] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/11/2014] [Indexed: 12/26/2022] Open
Abstract
DNA replication is a highly precise process that is initiated from origins of replication (ORIs) and is regulated by a set of regulatory proteins. The mining of DNA sequence information will be not only beneficial for understanding the regulatory mechanism of replication initiation but also for accurately identifying ORIs. In this study, the GC profile and GC skew were calculated to analyze the compositional bias in the Saccharomyces cerevisiae genome. We found that the GC profile in the region of ORIs is significantly lower than that in the flanking regions. By calculating the information redundancy, an estimation of the correlation of nucleotides, we found that the intensity of adjoining correlation in ORIs is dramatically higher than that in flanking regions. Furthermore, the relationships between ORIs and nucleosomes as well as transcription start sites were investigated. Results showed that ORIs are usually not occupied by nucleosomes. Finally, we calculated the distribution of ORIs in yeast chromosomes and found that most ORIs are in transcription terminal regions. We hope that these results will contribute to the identification of ORIs and the study of DNA replication mechanisms.
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Affiliation(s)
- Wen-Chao Li
- Key Laboratory for Neuro-Information of Ministry of Education, Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China Chengdu, China
| | - Zhe-Jin Zhong
- Key Laboratory for Neuro-Information of Ministry of Education, Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China Chengdu, China
| | - Pan-Pan Zhu
- Key Laboratory for Neuro-Information of Ministry of Education, Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China Chengdu, China
| | - En-Ze Deng
- Key Laboratory for Neuro-Information of Ministry of Education, Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China Chengdu, China
| | - Hui Ding
- Key Laboratory for Neuro-Information of Ministry of Education, Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China Chengdu, China
| | - Wei Chen
- Department of Physics, School of Sciences and Center for Genomics and Computational Biology, Hebei United University Tangshan, China
| | - Hao Lin
- Key Laboratory for Neuro-Information of Ministry of Education, Center of Bioinformatics, School of Life Science and Technology, University of Electronic Science and Technology of China Chengdu, China
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