1
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Zhu X, Kanemaki MT. Replication initiation sites and zones in the mammalian genome: Where are they located and how are they defined? DNA Repair (Amst) 2024; 141:103713. [PMID: 38959715 DOI: 10.1016/j.dnarep.2024.103713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 06/14/2024] [Accepted: 06/15/2024] [Indexed: 07/05/2024]
Abstract
Eukaryotic DNA replication is a tightly controlled process that occurs in two main steps, i.e., licensing and firing, which take place in the G1 and S phases of the cell cycle, respectively. In Saccharomyces cerevisiae, the budding yeast, replication origins contain consensus sequences that are recognized and bound by the licensing factor Orc1-6, which then recruits the replicative Mcm2-7 helicase. By contrast, mammalian initiation sites lack such consensus sequences, and the mammalian ORC does not exhibit sequence specificity. Studies performed over the past decades have identified replication initiation sites in the mammalian genome using sequencing-based assays, raising the question of whether replication initiation occurs at confined sites or in broad zones across the genome. Although recent reports have shown that the licensed MCMs in mammalian cells are broadly distributed, suggesting that ORC-dependent licensing may not determine the initiation sites/zones, they are predominantly located upstream of actively transcribed genes. This review compares the mechanism of replication initiation in yeast and mammalian cells, summarizes the sequencing-based technologies used for the identification of initiation sites/zones, and proposes a possible mechanism of initiation-site/zone selection in mammalian cells. Future directions and challenges in this field are also discussed.
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Affiliation(s)
- Xiaoxuan Zhu
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Yata 1111, Shizuoka, Mishima 411-8540, Japan.
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Yata 1111, Shizuoka, Mishima 411-8540, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Yata 1111, Shizuoka, Mishima 411-8540, Japan; Department of Biological Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
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2
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Reed TT, Kendal AH, Wozniak KJ, Simmons LA. DNA replication initiation timing is important for maintaining genome integrity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.18.599555. [PMID: 38948856 PMCID: PMC11212987 DOI: 10.1101/2024.06.18.599555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
DNA replication is regulated by factors that promote or inhibit initiation. In Bacillus subtilis, YabA is a negative regulator of DNA replication initiation while the newly identified kinase CcrZ is a positive regulator. The consequences of under-initiation or over-initiation of DNA replication to genome stability remain unclear. In this work, we measure origin to terminus ratios as a proxy for replication initiation activity. We show that ΔccrZ and several ccrZ alleles under-initiate DNA replication while ablation of yabA or overproduction of CcrZ leads to over-initiation. We find that cells under-initiating DNA replication have few incidents of replication fork stress as determined by low formation of RecA-GFP foci compared with wild type. In contrast, cells over-initiating DNA replication show levels of RecA-GFP foci formation analogous to cells directly challenged with DNA damaging agents. We show that cells under-initiating and over-initiating DNA replication were both sensitive to mitomycin C and that changes in replication initiation frequency cause increased sensitivity to genotoxic stress. With these results, we propose that cells under-initiating DNA replication are sensitive to DNA damage due to a shortage of DNA for repair through homologous recombination. For cells over-initiating DNA replication, we propose that an increase in the number of replication forks leads to replication fork stress which is further exacerbated by chromosomal DNA damage. Together, our study shows that DNA replication initiation frequency must be tightly controlled as changes in initiation influence replication fork fate and the capacity of cells to efficiently repair damage to their genetic material.
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Affiliation(s)
- Tristan T. Reed
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Abigail H. Kendal
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Katherine J Wozniak
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
- Present address: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
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3
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Rojas P, Wang J, Guglielmi G, Sadurnì MM, Pavlou L, Leung GHD, Rajagopal V, Spill F, Saponaro M. Genome-wide identification of replication fork stalling/pausing sites and the interplay between RNA Pol II transcription and DNA replication progression. Genome Biol 2024; 25:126. [PMID: 38773641 PMCID: PMC11106976 DOI: 10.1186/s13059-024-03278-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 05/14/2024] [Indexed: 05/24/2024] Open
Abstract
BACKGROUND DNA replication progression can be affected by the presence of physical barriers like the RNA polymerases, leading to replication stress and DNA damage. Nonetheless, we do not know how transcription influences overall DNA replication progression. RESULTS To characterize sites where DNA replication forks stall and pause, we establish a genome-wide approach to identify them. This approach uses multiple timepoints during S-phase to identify replication fork/stalling hotspots as replication progresses through the genome. These sites are typically associated with increased DNA damage, overlapped with fragile sites and with breakpoints of rearrangements identified in cancers but do not overlap with replication origins. Overlaying these sites with a genome-wide analysis of RNA polymerase II transcription, we find that replication fork stalling/pausing sites inside genes are directly related to transcription progression and activity. Indeed, we find that slowing down transcription elongation slows down directly replication progression through genes. This indicates that transcription and replication can coexist over the same regions. Importantly, rearrangements found in cancers overlapping transcription-replication collision sites are detected in non-transformed cells and increase following treatment with ATM and ATR inhibitors. At the same time, we find instances where transcription activity favors replication progression because it reduces histone density. CONCLUSIONS Altogether, our findings highlight how transcription and replication overlap during S-phase, with both positive and negative consequences for replication fork progression and genome stability by the coexistence of these two processes.
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Affiliation(s)
- Patricia Rojas
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Jianming Wang
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Giovanni Guglielmi
- School of Mathematics, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Martina Mustè Sadurnì
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Lucas Pavlou
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Geoffrey Ho Duen Leung
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Vijay Rajagopal
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Fabian Spill
- School of Mathematics, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Marco Saponaro
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
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4
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Tian M, Wang Z, Su Z, Shibata E, Shibata Y, Dutta A, Zang C. Integrative analysis of DNA replication origins and ORC-/MCM-binding sites in human cells reveals a lack of overlap. eLife 2024; 12:RP89548. [PMID: 38567819 PMCID: PMC10990492 DOI: 10.7554/elife.89548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
Based on experimentally determined average inter-origin distances of ~100 kb, DNA replication initiates from ~50,000 origins on human chromosomes in each cell cycle. The origins are believed to be specified by binding of factors like the origin recognition complex (ORC) or CTCF or other features like G-quadruplexes. We have performed an integrative analysis of 113 genome-wide human origin profiles (from five different techniques) and five ORC-binding profiles to critically evaluate whether the most reproducible origins are specified by these features. Out of ~7.5 million union origins identified by all datasets, only 0.27% (20,250 shared origins) were reproducibly obtained in at least 20 independent SNS-seq datasets and contained in initiation zones identified by each of three other techniques, suggesting extensive variability in origin usage and identification. Also, 21% of the shared origins overlap with transcriptional promoters, posing a conundrum. Although the shared origins overlap more than union origins with constitutive CTCF-binding sites, G-quadruplex sites, and activating histone marks, these overlaps are comparable or less than that of known transcription start sites, so that these features could be enriched in origins because of the overlap of origins with epigenetically open, promoter-like sequences. Only 6.4% of the 20,250 shared origins were within 1 kb from any of the ~13,000 reproducible ORC-binding sites in human cancer cells, and only 4.5% were within 1 kb of the ~11,000 union MCM2-7-binding sites in contrast to the nearly 100% overlap in the two comparisons in the yeast, Saccharomyces cerevisiae. Thus, in human cancer cell lines, replication origins appear to be specified by highly variable stochastic events dependent on the high epigenetic accessibility around promoters, without extensive overlap between the most reproducible origins and currently known ORC- or MCM-binding sites.
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Affiliation(s)
- Mengxue Tian
- Center for Public Health Genomics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Biochemistry and Molecular Genetics, University of Virginia School of MedicineCharlottesvilleUnited States
| | - Zhenjia Wang
- Center for Public Health Genomics, University of Virginia School of MedicineCharlottesvilleUnited States
| | - Zhangli Su
- Department of Biochemistry and Molecular Genetics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Genetics, University of Alabama at BirminghamBirminghamUnited States
| | - Etsuko Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Genetics, University of Alabama at BirminghamBirminghamUnited States
| | - Yoshiyuki Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Genetics, University of Alabama at BirminghamBirminghamUnited States
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Genetics, University of Alabama at BirminghamBirminghamUnited States
| | - Chongzhi Zang
- Center for Public Health Genomics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Biochemistry and Molecular Genetics, University of Virginia School of MedicineCharlottesvilleUnited States
- Department of Public Health Sciences, University of VirginiaCharlottesvilleUnited States
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5
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Khamidullina AI, Abramenko YE, Bruter AV, Tatarskiy VV. Key Proteins of Replication Stress Response and Cell Cycle Control as Cancer Therapy Targets. Int J Mol Sci 2024; 25:1263. [PMID: 38279263 PMCID: PMC10816012 DOI: 10.3390/ijms25021263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/14/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
Replication stress (RS) is a characteristic state of cancer cells as they tend to exchange precision of replication for fast proliferation and increased genomic instability. To overcome the consequences of improper replication control, malignant cells frequently inactivate parts of their DNA damage response (DDR) pathways (the ATM-CHK2-p53 pathway), while relying on other pathways which help to maintain replication fork stability (ATR-CHK1). This creates a dependency on the remaining DDR pathways, vulnerability to further destabilization of replication and synthetic lethality of DDR inhibitors with common oncogenic alterations such as mutations of TP53, RB1, ATM, amplifications of MYC, CCNE1 and others. The response to RS is normally limited by coordination of cell cycle, transcription and replication. Inhibition of WEE1 and PKMYT1 kinases, which prevent unscheduled mitosis entry, leads to fragility of under-replicated sites. Recent evidence also shows that inhibition of Cyclin-dependent kinases (CDKs), such as CDK4/6, CDK2, CDK8/19 and CDK12/13 can contribute to RS through disruption of DNA repair and replication control. Here, we review the main causes of RS in cancers as well as main therapeutic targets-ATR, CHK1, PARP and their inhibitors.
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Affiliation(s)
- Alvina I. Khamidullina
- Laboratory of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia; (A.I.K.); (Y.E.A.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia
| | - Yaroslav E. Abramenko
- Laboratory of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia; (A.I.K.); (Y.E.A.)
| | - Alexandra V. Bruter
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia
| | - Victor V. Tatarskiy
- Laboratory of Molecular Oncobiology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia; (A.I.K.); (Y.E.A.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, 119334 Moscow, Russia
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6
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Irony-Tur Sinai M, Kerem B. Insights into common fragile site instability: DNA replication challenges at DNA repeat sequences. Emerg Top Life Sci 2023; 7:277-287. [PMID: 37876349 PMCID: PMC10754330 DOI: 10.1042/etls20230023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/08/2023] [Accepted: 10/12/2023] [Indexed: 10/26/2023]
Abstract
Common fragile sites (CFS) are specific genomic regions prone to chromosomal instability under conditions of DNA replication stress. CFSs manifest as breaks, gaps, and constrictions on metaphase chromosomes under mild replication stress. These replication-sensitive CFS regions are preferentially unstable during cancer development, as reflected by their association with copy number variants (CNVs) frequently arise in most tumor types. Over the years, it became clear that a combination of different characteristics underlies the enhanced sensitivity of CFSs to replication stress. As of today, there is a strong evidence that the core fragility regions along CFSs overlap with actively transcribed large genes with delayed replication timing upon replication stress. Recently, the mechanistic basis for CFS instability was further extended to regions which span topologically associated domain (TAD) boundaries, generating a fragility signature composed of replication, transcription and genome organization. The presence of difficult-to-replicate AT-rich repeats was one of the early features suggested to characterize a subgroup of CFSs. These long stretches of AT-dinucleotide have the potential to fold into stable secondary structures which may impede replication fork progression, leaving the region under-replicated. Here, we focus on the molecular mechanisms underlying repeat instability at CFSs and on the proteins involved in the resolution of secondary structure impediments arising along repetitive sequence elements which are essential for the maintenance of genome stability.
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Affiliation(s)
- Michal Irony-Tur Sinai
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
| | - Batsheva Kerem
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
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7
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Tian M, Wang Z, Su Z, Shibata E, Shibata Y, Dutta A, Zang C. Integrative analysis of DNA replication origins and ORC/MCM binding sites in human cells reveals a lack of overlap. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550556. [PMID: 37546918 PMCID: PMC10402023 DOI: 10.1101/2023.07.25.550556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Based on experimentally determined average inter-origin distances of ∼100 kb, DNA replication initiates from ∼50,000 origins on human chromosomes in each cell cycle. The origins are believed to be specified by binding of factors like the Origin Recognition Complex (ORC) or CTCF or other features like G-quadruplexes. We have performed an integrative analysis of 113 genome-wide human origin profiles (from five different techniques) and 5 ORC-binding profiles to critically evaluate whether the most reproducible origins are specified by these features. Out of ∼7.5 million union origins identified by all datasets, only 0.27% were reproducibly obtained in at least 20 independent SNS-seq datasets and contained in initiation zones identified by each of three other techniques (20,250 shared origins), suggesting extensive variability in origin usage and identification. 21% of the shared origins overlap with transcriptional promoters, posing a conundrum. Although the shared origins overlap more than union origins with constitutive CTCF binding sites, G-quadruplex sites and activating histone marks, these overlaps are comparable or less than that of known Transcription Start Sites, so that these features could be enriched in origins because of the overlap of origins with epigenetically open, promoter-like sequences. Only 6.4% of the 20,250 shared origins were within 1 kb from any of the ∼13,000 reproducible ORC binding sites in human cancer cells, and only 4.5% were within 1 kb of the ∼11,000 union MCM2-7 binding sites in contrast to the nearly 100% overlap in the two comparisons in the yeast, S. cerevisiae . Thus, in human cancer cell lines, replication origins appear to be specified by highly variable stochastic events dependent on the high epigenetic accessibility around promoters, without extensive overlap between the most reproducible origins and currently known ORC- or MCM-binding sites.
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8
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Eladl A, Yamaoki Y, Kamba K, Hoshina S, Horinouchi H, Kondo K, Waga S, Nagata T, Katahira M. NMR characterization of the structure of the intrinsically disordered region of human origin recognition complex subunit 1, hORC1, and of its interaction with G-quadruplex DNAs. Biochem Biophys Res Commun 2023; 683:149112. [PMID: 37857165 DOI: 10.1016/j.bbrc.2023.10.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023]
Abstract
Human origin recognition complex (hORC) binds to the DNA replication origin and then initiates DNA replication. However, hORC does not exhibit DNA sequence-specificity and how hORC recognizes the replication origin on genomic DNA remains elusive. Previously, we found that hORC recognizes G-quadruplex structures potentially formed near the replication origin. Then, we showed that hORC subunit 1 (hORC1) preferentially binds to G-quadruplex DNAs using a hORC1 construct comprising residues 413 to 511 (hORC1413-511). Here, we investigate the structural characteristics of hORC1413-511 in its free and complex forms with G-quadruplex DNAs. Circular dichroism and nuclear magnetic resonance (NMR) spectroscopic studies indicated that hORC1413-511 is disordered except for a short α-helical region in both the free and complex forms. NMR chemical shift perturbation (CSP) analysis suggested that basic residues, arginines and lysines, and polar residues, serines and threonines, are involved in the G-quadruplex DNA binding. Then, this was confirmed by mutation analysis. Interestingly, CSP analysis indicated that hORC1413-511 binds to both parallel- and (3 + 1)-type G-quadruplex DNAs using the same residues, and thereby in the same manner. Our study suggests that hORC1 uses its intrinsically disordered G-quadruplex binding region to recognize parallel-type and (3 + 1)-type G-quadruplex structures at replication origin.
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Affiliation(s)
- Afaf Eladl
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan; Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig, 44519, Egypt
| | - Yudai Yamaoki
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan; Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Japan; Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Keisuke Kamba
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan; Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Shoko Hoshina
- Department of Chemical and Biological Sciences, Japan Women's University, Tokyo, 112-8681, Japan
| | - Haruka Horinouchi
- Department of Chemical and Biological Sciences, Japan Women's University, Tokyo, 112-8681, Japan
| | - Keiko Kondo
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan; Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Japan; Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Shou Waga
- Department of Chemical and Biological Sciences, Japan Women's University, Tokyo, 112-8681, Japan
| | - Takashi Nagata
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan; Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Japan; Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Masato Katahira
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan; Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan; Integrated Research Center for Carbon Negative Science, Institute of Advanced Energy, Kyoto University, Uji, 611-0011, Japan; Biomass Product Tree Industry-Academia Collaborative Research Laboratory, Kyoto University, Uji, Kyoto, 611-0011, Japan.
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9
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Shekhar S, Verma S, Gupta MK, Roy SS, Kaur I, Krishnamachari A, Dhar SK. Genome-wide binding sites of Plasmodium falciparum mini chromosome maintenance protein MCM6 show new insights into parasite DNA replication. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119546. [PMID: 37482133 DOI: 10.1016/j.bbamcr.2023.119546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 07/08/2023] [Accepted: 07/16/2023] [Indexed: 07/25/2023]
Abstract
Multiple rounds of DNA replication take place in various stages of the life cycle in the human malaria parasite Plasmodium falciparum. Previous bioinformatics analysis has shown the presence of putative Autonomously Replicating Sequence (ARS) like sequences in the Plasmodium genome. However, the actual sites and frequency of replication origins in the P. falciparum genome based on experimental data still remain elusive. Minichromosome maintenance (MCM) proteins are recruited by the Origin recognition complex (ORC) to the origins of replication in eukaryotes including P. falciparum. We used PfMCM6 for chromatin immunoprecipitation followed by sequencing (ChIP-seq) in the quest for identification of putative replication origins in the parasite. PfMCM6 DNA binding sites annotation revealed high enrichment at exon regions. This is contrary to higher eukaryotes that show an inclination of origin sites towards transcriptional start sites. ChIP-seq results were further validated by ChIP-qPCR results as well as nascent strand abundance assay at the selected PfMCM6 enriched sites that also showed preferential binding of PfORC1 suggesting potential of these sites as origin sites. Further, PfMCM6 ChIP-seq data showed a positive correlation with previously published histone H4K8Ac genome-wide binding sites but not with H3K9Ac sites suggesting epigenetic control of replication initiation sites in the parasites. Overall, our data show the genome-wide distribution of PfMCM6 binding sites with their potential as replication origins in this deadly human pathogen that not only broadens our knowledge of parasite DNA replication and its unique biology, it may help to find new avenues for intervention processes.
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Affiliation(s)
- Shashank Shekhar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Sunita Verma
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mohit Kumar Gupta
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Sourav Singha Roy
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | - Inderjeet Kaur
- Department of Biotechnology, Central University of Haryana, Mahendergargh, India
| | | | - Suman Kumar Dhar
- Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India.
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10
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Mas AM, Goñi E, Ruiz de Los Mozos I, Arcas A, Statello L, González J, Blázquez L, Lee WTC, Gupta D, Sejas Á, Hoshina S, Armaos A, Tartaglia GG, Waga S, Ule J, Rothenberg E, Gómez M, Huarte M. ORC1 binds to cis-transcribed RNAs for efficient activation of replication origins. Nat Commun 2023; 14:4447. [PMID: 37488096 PMCID: PMC10366126 DOI: 10.1038/s41467-023-40105-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/11/2023] [Indexed: 07/26/2023] Open
Abstract
Cells must coordinate the activation of thousands of replication origins dispersed throughout their genome. Active transcription is known to favor the formation of mammalian origins, although the role that RNA plays in this process remains unclear. We show that the ORC1 subunit of the human Origin Recognition Complex interacts with RNAs transcribed from genes with origins in their transcription start sites (TSSs), displaying a positive correlation between RNA binding and origin activity. RNA depletion, or the use of ORC1 RNA-binding mutant, result in inefficient activation of proximal origins, linked to impaired ORC1 chromatin release. ORC1 RNA binding activity resides in its intrinsically disordered region, involved in intra- and inter-molecular interactions, regulation by phosphorylation, and phase-separation. We show that RNA binding favors ORC1 chromatin release, by regulating its phosphorylation and subsequent degradation. Our results unveil a non-coding function of RNA as a dynamic component of the chromatin, orchestrating the activation of replication origins.
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Affiliation(s)
- Aina Maria Mas
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Enrique Goñi
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Igor Ruiz de Los Mozos
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Aida Arcas
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Luisa Statello
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Jovanna González
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Lorea Blázquez
- RNA Networks Lab, The Francis Crick Institute, NW11BF, London, UK
- Neurosciences Area, Biodonostia Health Research Institute, 20014, San Sebastian, Spain
- Ikerbasque, Basque Foundation for Science, 48009, Bilbao, Spain
| | - Wei Ting Chelsea Lee
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Dipika Gupta
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - Álvaro Sejas
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Shoko Hoshina
- Department of Chemical and Biological Sciences, Japan Women's University, Tokyo, 112-8681, Japan
| | - Alexandros Armaos
- Center for Human Technologies, Istituto Italiano di Tecnologia, Genova, Italy
| | - Gian Gaetano Tartaglia
- Center for Human Technologies, Istituto Italiano di Tecnologia, Genova, Italy
- Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Department of Biology 'Charles Darwin', Sapienza University of Rome, Rome, Italy
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Shou Waga
- Department of Chemical and Biological Sciences, Japan Women's University, Tokyo, 112-8681, Japan
| | - Jernej Ule
- RNA Networks Lab, The Francis Crick Institute, NW11BF, London, UK
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, Perlmutter Cancer Center, New York University School of Medicine, New York, NY, 10016, USA
| | - María Gómez
- Centro de Biología Molecular Severo Ochoa (CBMSO), Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid (CSIC/UAM), Nicolás Cabrera 1, 28049, Madrid, Spain
| | - Maite Huarte
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 31008, Pamplona, Spain.
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain.
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11
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Han ZQ, Wen LN. Application of G-quadruplex targets in gastrointestinal cancers: Advancements, challenges and prospects. World J Gastrointest Oncol 2023; 15:1149-1173. [PMID: 37546556 PMCID: PMC10401460 DOI: 10.4251/wjgo.v15.i7.1149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 04/11/2023] [Accepted: 05/08/2023] [Indexed: 07/12/2023] Open
Abstract
Genomic instability and inflammation are considered to be two enabling characteristics that support cancer development and progression. G-quadruplex structure is a key element that contributes to genomic instability and inflammation. G-quadruplexes were once regarded as simply an obstacle that can block the transcription of oncogenes. A ligand targeting G-quadruplexes was found to have anticancer activity, making G-quadruplexes potential anticancer targets. However, further investigation has revealed that G-quadruplexes are widely distributed throughout the human genome and have many functions, such as regulating DNA replication, DNA repair, transcription, translation, epigenetics, and inflammatory response. G-quadruplexes play double regulatory roles in transcription and translation. In this review, we focus on G-quadruplexes as novel targets for the treatment of gastrointestinal cancers. We summarize the application basis of G-quadruplexes in gastrointestinal cancers, including their distribution sites, structural characteristics, and physiological functions. We describe the current status of applications for the treatment of esophageal cancer, pancreatic cancer, hepatocellular carcinoma, gastric cancer, colorectal cancer, and gastrointestinal stromal tumors, as well as the associated challenges. Finally, we review the prospective clinical applications of G-quadruplex targets, providing references for targeted treatment strategies in gastrointestinal cancers.
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Affiliation(s)
- Zong-Qiang Han
- Department of Laboratory Medicine, Beijing Xiaotangshan Hospital, Beijing 102211, China
| | - Li-Na Wen
- Department of Clinical Nutrition, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, China
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12
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Brison O, Gnan S, Azar D, Koundrioukoff S, Melendez-Garcia R, Kim SJ, Schmidt M, El-Hilali S, Jaszczyszyn Y, Lachages AM, Thermes C, Chen CL, Debatisse M. Mistimed origin licensing and activation stabilize common fragile sites under tight DNA-replication checkpoint activation. Nat Struct Mol Biol 2023; 30:539-550. [PMID: 37024657 DOI: 10.1038/s41594-023-00949-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 02/28/2023] [Indexed: 04/08/2023]
Abstract
Genome integrity requires replication to be completed before chromosome segregation. The DNA-replication checkpoint (DRC) contributes to this coordination by inhibiting CDK1, which delays mitotic onset. Under-replication of common fragile sites (CFSs), however, escapes surveillance, resulting in mitotic chromosome breaks. Here we asked whether loose DRC activation induced by modest stresses commonly used to destabilize CFSs could explain this leakage. We found that tightening DRC activation or CDK1 inhibition stabilizes CFSs in human cells. Repli-Seq and molecular combing analyses showed a burst of replication initiations implemented in mid S-phase across a subset of late-replicating sequences, including CFSs, while the bulk genome was unaffected. CFS rescue and extra-initiations required CDC6 and CDT1 availability in S-phase, implying that CDK1 inhibition permits mistimed origin licensing and firing. In addition to delaying mitotic onset, tight DRC activation therefore supports replication completion of late origin-poor domains at risk of under-replication, two complementary roles preserving genome stability.
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Affiliation(s)
- Olivier Brison
- CNRS UMR 9019, Gustave Roussy Institute, Villejuif, France
- Paris-Saclay University, Gif-sur-Yvette, France
| | - Stefano Gnan
- Curie Institute, PSL Research University, CNRS UMR 3244, Paris, France
- Sorbonne University, Paris, France
| | - Dana Azar
- Curie Institute, PSL Research University, CNRS UMR 3244, Paris, France
- Sorbonne University, Paris, France
- Laboratoire Biodiversité et Génomique Fonctionnelle, Faculté des Sciences, Université Saint-Joseph, Beirut, Lebanon
| | - Stéphane Koundrioukoff
- CNRS UMR 9019, Gustave Roussy Institute, Villejuif, France
- Sorbonne University, Paris, France
| | - Rodrigo Melendez-Garcia
- CNRS UMR 9019, Gustave Roussy Institute, Villejuif, France
- Paris-Saclay University, Gif-sur-Yvette, France
| | - Su-Jung Kim
- CNRS UMR 9019, Gustave Roussy Institute, Villejuif, France
- Paris-Saclay University, Gif-sur-Yvette, France
| | - Mélanie Schmidt
- CNRS UMR 9019, Gustave Roussy Institute, Villejuif, France
- Paris-Saclay University, Gif-sur-Yvette, France
| | - Sami El-Hilali
- Curie Institute, PSL Research University, CNRS UMR 3244, Paris, France
- Sorbonne University, Paris, France
- Villefranche sur mer Developmental Biology Laboratory, CNRS UMR7009, Villefranche-sur-Mer, France
| | - Yan Jaszczyszyn
- Paris-Saclay University, Gif-sur-Yvette, France
- Institute for Integrative Biology of the Cell (I2BC), UMR 9198CNRS, CEA, Paris-Sud University, Gif-sur-Yvette, France
| | - Anne-Marie Lachages
- Curie Institute, PSL Research University, CNRS UMR 3244, Paris, France
- UTCBS, CNRS UMR 8258/ INSERM U 1267, Sorbonne-Paris-Cité University, Paris, France
| | - Claude Thermes
- Paris-Saclay University, Gif-sur-Yvette, France
- Institute for Integrative Biology of the Cell (I2BC), UMR 9198CNRS, CEA, Paris-Sud University, Gif-sur-Yvette, France
| | - Chun-Long Chen
- Curie Institute, PSL Research University, CNRS UMR 3244, Paris, France
- Sorbonne University, Paris, France
| | - Michelle Debatisse
- CNRS UMR 9019, Gustave Roussy Institute, Villejuif, France.
- Sorbonne University, Paris, France.
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13
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Jaksik R, Wheeler DA, Kimmel M. Detection and characterization of constitutive replication origins defined by DNA polymerase epsilon. BMC Biol 2023; 21:41. [PMID: 36829160 PMCID: PMC9960419 DOI: 10.1186/s12915-023-01527-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 01/24/2023] [Indexed: 02/26/2023] Open
Abstract
BACKGROUND Despite the process of DNA replication being mechanistically highly conserved, the location of origins of replication (ORI) may vary from one tissue to the next, or between rounds of replication in eukaryotes, suggesting flexibility in the choice of locations to initiate replication. Lists of human ORI therefore vary widely in number and location, and there are currently no methods available to compare them. Here, we propose a method of detection of ORI based on somatic mutation patterns generated by the mutator phenotype of damaged DNA polymerase epsilon (POLE). RESULTS We report the genome-wide localization of constitutive ORI in POLE-mutated human tumors using whole genome sequencing data. Mutations accumulated after many rounds of replication of unsynchronized dividing cell populations in tumors allow to identify constitutive origins, which we show are shared with high fidelity between individuals and tumor types. Using a Smith-Waterman-like dynamic programming approach, we compared replication origin positions obtained from multiple different methods. The comparison allowed us to define a consensus set of replication origins, identified consistently by multiple ORI detection methods. Many DNA features co-localized with the consensus set of ORI, including chromatin loop anchors, G-quadruplexes, S/MARs, and CpGs. Among all features, the H2A.Z histone exhibited the most significant association. CONCLUSIONS Our results show that mutation-based detection of replication origins is a viable approach to determining their location and associated sequence features.
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Affiliation(s)
- Roman Jaksik
- Department of Systems Biology and Engineering and Biotechnology Centre, Silesian University of Technology, Gliwice, Poland.
| | - David A. Wheeler
- grid.39382.330000 0001 2160 926XHuman Genome Sequencing Centre, Baylor College of Medicine, Houston, TX USA ,grid.240871.80000 0001 0224 711XPresent Address: Clinical Genomics Group, Department of Computational Biology, St Jude Children’s Research Hospital, Memphis, TN 38103 USA
| | - Marek Kimmel
- grid.6979.10000 0001 2335 3149Department of Systems Biology and Engineering and Biotechnology Centre, Silesian University of Technology, Gliwice, Poland ,grid.21940.3e0000 0004 1936 8278Department of Statistics, Rice University, Houston, TX USA ,grid.21940.3e0000 0004 1936 8278Department of Bioengineering, Rice University, Houston, TX USA
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14
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Jodkowska K, Pancaldi V, Rigau M, Almeida R, Fernández-Justel J, Graña-Castro O, Rodríguez-Acebes S, Rubio-Camarillo M, Carrillo-de Santa Pau E, Pisano D, Al-Shahrour F, Valencia A, Gómez M, Méndez J. 3D chromatin connectivity underlies replication origin efficiency in mouse embryonic stem cells. Nucleic Acids Res 2022; 50:12149-12165. [PMID: 36453993 PMCID: PMC9757045 DOI: 10.1093/nar/gkac1111] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/31/2022] [Accepted: 11/25/2022] [Indexed: 12/03/2022] Open
Abstract
In mammalian cells, chromosomal replication starts at thousands of origins at which replisomes are assembled. Replicative stress triggers additional initiation events from 'dormant' origins whose genomic distribution and regulation are not well understood. In this study, we have analyzed origin activity in mouse embryonic stem cells in the absence or presence of mild replicative stress induced by aphidicolin, a DNA polymerase inhibitor, or by deregulation of origin licensing factor CDC6. In both cases, we observe that the majority of stress-responsive origins are also active in a small fraction of the cell population in a normal S phase, and stress increases their frequency of activation. In a search for the molecular determinants of origin efficiency, we compared the genetic and epigenetic features of origins displaying different levels of activation, and integrated their genomic positions in three-dimensional chromatin interaction networks derived from high-depth Hi-C and promoter-capture Hi-C data. We report that origin efficiency is directly proportional to the proximity to transcriptional start sites and to the number of contacts established between origin-containing chromatin fragments, supporting the organization of origins in higher-level DNA replication factories.
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Affiliation(s)
| | | | | | | | - José M Fernández-Justel
- Functional Organization of the Mammalian Genome Group, Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Madrid, Spain
| | - Osvaldo Graña-Castro
- Bioinformatics Unit, Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain,Institute of Applied Molecular Medicine (IMMA-Nemesio Díez), San Pablo-CEU University, Boadilla del Monte, Madrid, Spain
| | - Sara Rodríguez-Acebes
- DNA Replication Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Miriam Rubio-Camarillo
- Bioinformatics Unit, Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | | | - David Pisano
- Bioinformatics Unit, Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Fátima Al-Shahrour
- Bioinformatics Unit, Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Alfonso Valencia
- Computational Biology Life Sciences Group, Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | - María Gómez
- Correspondence may also be addressed to María Gómez. Tel: +34 911964724; Fax: +34 911964420;
| | - Juan Méndez
- To whom correspondence should be addressed. Tel: +34 917328000; Fax: +34 917328033;
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15
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Ji F, Zhu X, Liao H, Ouyang L, Huang Y, Syeda MZ, Ying S. New Era of Mapping and Understanding Common Fragile Sites: An Updated Review on Origin of Chromosome Fragility. Front Genet 2022; 13:906957. [PMID: 35669181 PMCID: PMC9164283 DOI: 10.3389/fgene.2022.906957] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Common fragile sites (CFSs) are specific genomic loci prone to forming gaps or breakages upon replication perturbation, which correlate well with chromosomal rearrangement and copy number variation. CFSs have been actively studied due to their important pathophysiological relevance in different diseases such as cancer and neurological disorders. The genetic locations and sequences of CFSs are crucial to understanding the origin of such unstable sites, which require reliable mapping and characterizing approaches. In this review, we will inspect the evolving techniques for CFSs mapping, especially genome-wide mapping and sequencing of CFSs based on current knowledge of CFSs. We will also revisit the well-established hypotheses on the origin of CFSs fragility, incorporating novel findings from the comprehensive analysis of finely mapped CFSs regarding their locations, sequences, and replication/transcription, etc. This review will present the most up-to-date picture of CFSs and, potentially, a new framework for future research of CFSs.
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Affiliation(s)
- Fang Ji
- International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.,Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Xinli Zhu
- Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Hongwei Liao
- International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.,Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Liujian Ouyang
- Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingfei Huang
- Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Madiha Zahra Syeda
- Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Songmin Ying
- International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.,Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
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16
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Thakur BL, Baris AM, Fu H, Redon CE, Pongor L, Mosavarpour S, Gross J, Jang SM, Sebastian R, Utani K, Jenkins L, Indig F, Aladjem M. Convergence of SIRT1 and ATR signaling to modulate replication origin dormancy. Nucleic Acids Res 2022; 50:5111-5128. [PMID: 35524559 PMCID: PMC9122590 DOI: 10.1093/nar/gkac299] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 04/08/2022] [Accepted: 04/13/2022] [Indexed: 11/15/2023] Open
Abstract
During routine genome duplication, many potential replication origins remain inactive or 'dormant'. Such origin dormancy is achieved, in part, by an interaction with the metabolic sensor SIRT1 deacetylase. We report here that dormant origins are a group of consistent, pre-determined genomic sequences that are distinguished from baseline (i.e. ordinarily active) origins by their preferential association with two phospho-isoforms of the helicase component MCM2. During normal unperturbed cell growth, baseline origins, but not dormant origins, associate with a form of MCM2 that is phosphorylated by DBF4-dependent kinase (DDK) on serine 139 (pS139-MCM2). This association facilitates the initiation of DNA replication from baseline origins. Concomitantly, SIRT1 inhibits Ataxia Telangiectasia and Rad3-related (ATR)-kinase-mediated phosphorylation of MCM2 on serine 108 (pS108-MCM2) by deacetylating the ATR-interacting protein DNA topoisomerase II binding protein 1 (TOPBP1), thereby preventing ATR recruitment to chromatin. In cells devoid of SIRT1 activity, or challenged by replication stress, this inhibition is circumvented, enabling ATR-mediated S108-MCM2 phosphorylation. In turn, pS108-MCM2 enables DDK-mediated phosphorylation on S139-MCM2 and facilitates replication initiation at dormant origins. These observations suggest that replication origin dormancy and activation are regulated by distinct post-translational MCM modifications that reflect a balance between SIRT1 activity and ATR signaling.
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Affiliation(s)
- Bhushan L Thakur
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Adrian M Baris
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Haiqing Fu
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Christophe E Redon
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Lorinc S Pongor
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Sara Mosavarpour
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Jacob M Gross
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Sang-Min Jang
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Robin Sebastian
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Koichi Utani
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Lisa M Jenkins
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
| | - Fred E Indig
- Confocal Imaging Facility, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Mirit I Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
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17
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A DNA replication-independent function of pre-replication complex genes during cell invasion in C. elegans. PLoS Biol 2022; 20:e3001317. [PMID: 35192608 PMCID: PMC8863262 DOI: 10.1371/journal.pbio.3001317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/01/2021] [Indexed: 11/19/2022] Open
Abstract
Cell invasion is an initiating event during tumor cell metastasis and an essential process during development. A screen of C. elegans orthologs of genes overexpressed in invasive human melanoma cells has identified several components of the conserved DNA pre-replication complex (pre-RC) as positive regulators of anchor cell (AC) invasion. The pre-RC genes function cell-autonomously in the G1-arrested AC to promote invasion, independently of their role in licensing DNA replication origins in proliferating cells. While the helicase activity of the pre-RC is necessary for AC invasion, the downstream acting DNA replication initiation factors are not required. The pre-RC promotes the invasive fate by regulating the expression of extracellular matrix genes and components of the PI3K signaling pathway. Increasing PI3K pathway activity partially suppressed the AC invasion defects caused by pre-RC depletion, suggesting that the PI3K pathway is one critical pre-RC target. We propose that the pre-RC, or a part of it, acts in the postmitotic AC as a transcriptional regulator that facilitates the switch to an invasive phenotype.
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18
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Kim S, Hwang S. G-Quadruplex Matters in Tissue-Specific Tumorigenesis by BRCA1 Deficiency. Genes (Basel) 2022; 13:genes13030391. [PMID: 35327946 PMCID: PMC8948836 DOI: 10.3390/genes13030391] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 12/14/2022] Open
Abstract
How and why distinct genetic alterations, such as BRCA1 mutation, promote tumorigenesis in certain tissues, but not others, remain an important issue in cancer research. The underlying mechanisms may reveal tissue-specific therapeutic vulnerabilities. Although the roles of BRCA1, such as DNA damage repair and stalled fork stabilization, obviously contribute to tumor suppression, these ubiquitously important functions cannot explain tissue-specific tumorigenesis by BRCA1 mutations. Recent advances in our understanding of the cancer genome and fundamental cellular processes on DNA, such as transcription and DNA replication, have provided new insights regarding BRCA1-associated tumorigenesis, suggesting that G-quadruplex (G4) plays a critical role. In this review, we summarize the importance of G4 structures in mutagenesis of the cancer genome and cell type-specific gene regulation, and discuss a recently revealed molecular mechanism of G4/base excision repair (BER)-mediated transcriptional activation. The latter adequately explains the correlation between the accumulation of unresolved transcriptional regulatory G4s and multi-level genomic alterations observed in BRCA1-associated tumors. In summary, tissue-specific tumorigenesis by BRCA1 deficiency can be explained by cell type-specific levels of transcriptional regulatory G4s and the role of BRCA1 in resolving it. This mechanism would provide an integrated understanding of the initiation and development of BRCA1-associated tumors.
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Affiliation(s)
- Sanghyun Kim
- Department of Biomedical Science, College of Life Science, CHA University, Sungnam 13488, Korea;
| | - Sohyun Hwang
- Department of Biomedical Science, College of Life Science, CHA University, Sungnam 13488, Korea;
- Department of Pathology, CHA Bundang Medical Center, CHA University School of Medicine, Sungnam 13496, Korea
- Correspondence:
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19
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Thakur BL, Ray A, Redon CE, Aladjem MI. Preventing excess replication origin activation to ensure genome stability. Trends Genet 2022; 38:169-181. [PMID: 34625299 PMCID: PMC8752500 DOI: 10.1016/j.tig.2021.09.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 02/03/2023]
Abstract
Cells activate distinctive regulatory pathways that prevent excessive initiation of DNA replication to achieve timely and accurate genome duplication. Excess DNA synthesis is constrained by protein-DNA interactions that inhibit initiation at dormant origins. In parallel, specific modifications of pre-replication complexes prohibit post-replicative origin relicensing. Replication stress ensues when the controls that prevent excess replication are missing in cancer cells, which often harbor extrachromosomal DNA that can be further amplified by recombination-mediated processes to generate chromosomal translocations. The genomic instability that accompanies excess replication origin activation can provide a promising target for therapeutic intervention. Here we review molecular pathways that modulate replication origin dormancy, prevent excess origin activation, and detect, encapsulate, and eliminate persistent excess DNA.
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Affiliation(s)
- Bhushan L Thakur
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Anagh Ray
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Christophe E Redon
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Mirit I Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.
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20
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Mei L, Kedziora KM, Song EA, Purvis JE, Cook J. The consequences of differential origin licensing dynamics in distinct chromatin environments. Nucleic Acids Res 2022; 50:9601-9620. [PMID: 35079814 PMCID: PMC9508807 DOI: 10.1093/nar/gkac003] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/17/2021] [Accepted: 01/05/2022] [Indexed: 02/01/2023] Open
Abstract
Eukaryotic chromosomes contain regions of varying accessibility, yet DNA replication factors must access all regions. The first replication step is loading MCM complexes to license replication origins during the G1 cell cycle phase. It is not yet known how mammalian MCM complexes are adequately distributed to both accessible euchromatin regions and less accessible heterochromatin regions. To address this question, we combined time-lapse live-cell imaging with immunofluorescence imaging of single human cells to quantify the relative rates of MCM loading in euchromatin and heterochromatin throughout G1. We report here that MCM loading in euchromatin is faster than that in heterochromatin in early G1, but surprisingly, heterochromatin loading accelerates relative to euchromatin loading in middle and late G1. This differential acceleration allows both chromatin types to begin S phase with similar concentrations of loaded MCM. The different loading dynamics require ORCA-dependent differences in origin recognition complex distribution. A consequence of heterochromatin licensing dynamics is that cells experiencing a truncated G1 phase from premature cyclin E expression enter S phase with underlicensed heterochromatin, and DNA damage accumulates preferentially in heterochromatin in the subsequent S/G2 phase. Thus, G1 length is critical for sufficient MCM loading, particularly in heterochromatin, to ensure complete genome duplication and to maintain genome stability.
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Affiliation(s)
- Liu Mei
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Katarzyna M Kedziora
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Bioinformatics and Analytics Research Collaborative (BARC), University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Eun-Ah Song
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeremy E Purvis
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeanette Gowen Cook
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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21
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Wu W, He JN, Lan M, Zhang P, Chu WK. Transcription-Replication Collisions and Chromosome Fragility. Front Genet 2021; 12:804547. [PMID: 34956339 PMCID: PMC8703014 DOI: 10.3389/fgene.2021.804547] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
Accurate replication of the entire genome is critical for cell division and propagation. Certain regions in the genome, such as fragile sites (common fragile sites, rare fragile sites, early replicating fragile sites), rDNA and telomeres, are intrinsically difficult to replicate, especially in the presence of replication stress caused by, for example, oncogene activation during tumor development. Therefore, these regions are particularly prone to deletions and chromosome rearrangements during tumorigenesis, rendering chromosome fragility. Although, the mechanism underlying their “difficult-to-replicate” nature and genomic instability is still not fully understood, accumulating evidence suggests transcription might be a major source of endogenous replication stress (RS) leading to chromosome fragility. Here, we provide an updated overview of how transcription affects chromosome fragility. Furthermore, we will use the well characterized common fragile sites (CFSs) as a model to discuss pathways involved in offsetting transcription-induced RS at these loci with a focus on the recently discovered atypical DNA synthesis repair pathway Mitotic DNA Synthesis (MiDAS).
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Affiliation(s)
- Wei Wu
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Jing Na He
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong, China
| | - Mengjiao Lan
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Pumin Zhang
- Zhejiang Provincial Key Laboratory of Pancreatic Diseases, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Wai Kit Chu
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, Hong Kong, China
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22
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Hayashi-Takanaka Y, Hayashi Y, Hirano Y, Miyawaki-Kuwakado A, Ohkawa Y, Obuse C, Kimura H, Haraguchi T, Hiraoka Y. Chromatin loading of MCM hexamers is associated with di-/tri-methylation of histone H4K20 toward S phase entry. Nucleic Acids Res 2021; 49:12152-12166. [PMID: 34817054 PMCID: PMC8643670 DOI: 10.1093/nar/gkab1068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 09/29/2021] [Accepted: 10/20/2021] [Indexed: 12/30/2022] Open
Abstract
DNA replication is a key step in initiating cell proliferation. Loading hexameric complexes of minichromosome maintenance (MCM) helicase onto DNA replication origins during the G1 phase is essential for initiating DNA replication. Here, we examined MCM hexamer states during the cell cycle in human hTERT-RPE1 cells using multicolor immunofluorescence-based, single-cell plot analysis, and biochemical size fractionation. Experiments involving cell-cycle arrest at the G1 phase and release from the arrest revealed that a double MCM hexamer was formed via a single hexamer during G1 progression. A single MCM hexamer was recruited to chromatin in the early G1 phase. Another single hexamer was recruited to form a double hexamer in the late G1 phase. We further examined relationship between the MCM hexamer states and the methylation levels at lysine 20 of histone H4 (H4K20) and found that the double MCM hexamer state was correlated with di/trimethyl-H4K20 (H4K20me2/3). Inhibiting the conversion from monomethyl-H4K20 (H4K20me1) to H4K20me2/3 retained the cells in the single MCM hexamer state. Non-proliferative cells, including confluent cells or Cdk4/6 inhibitor-treated cells, also remained halted in the single MCM hexamer state. We propose that the single MCM hexamer state is a halting step in the determination of cell cycle progression.
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Affiliation(s)
- Yoko Hayashi-Takanaka
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
| | - Yuichiro Hayashi
- Institute of Biomedical Sciences, Kansai Medical University, 2-5-1 Shin-machi, Hirakata 573-1010, Japan
| | - Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
| | - Atsuko Miyawaki-Kuwakado
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yasuyuki Ohkawa
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Chikashi Obuse
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043, Japan
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita 565-0871, Japan
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23
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Efficiency and equity in origin licensing to ensure complete DNA replication. Biochem Soc Trans 2021; 49:2133-2141. [PMID: 34545932 DOI: 10.1042/bst20210161] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/19/2021] [Accepted: 08/31/2021] [Indexed: 12/21/2022]
Abstract
The cell division cycle must be strictly regulated during both development and adult maintenance, and efficient and well-controlled DNA replication is a key event in the cell cycle. DNA replication origins are prepared in G1 phase of the cell cycle in a process known as origin licensing which is essential for DNA replication initiation in the subsequent S phase. Appropriate origin licensing includes: (1) Licensing enough origins at adequate origin licensing speed to complete licensing before G1 phase ends; (2) Licensing origins such that they are well-distributed on all chromosomes. Both aspects of licensing are critical for replication efficiency and accuracy. In this minireview, we will discuss recent advances in defining how origin licensing speed and distribution are critical to ensure DNA replication completion and genome stability.
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24
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St Germain C, Zhao H, Barlow JH. Transcription-Replication Collisions-A Series of Unfortunate Events. Biomolecules 2021; 11:1249. [PMID: 34439915 PMCID: PMC8391903 DOI: 10.3390/biom11081249] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/12/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Transcription-replication interactions occur when DNA replication encounters genomic regions undergoing transcription. Both replication and transcription are essential for life and use the same DNA template making conflicts unavoidable. R-loops, DNA supercoiling, DNA secondary structure, and chromatin-binding proteins are all potential obstacles for processive replication or transcription and pose an even more potent threat to genome integrity when these processes co-occur. It is critical to maintaining high fidelity and processivity of transcription and replication while navigating through a complex chromatin environment, highlighting the importance of defining cellular pathways regulating transcription-replication interaction formation, evasion, and resolution. Here we discuss how transcription influences replication fork stability, and the safeguards that have evolved to navigate transcription-replication interactions and maintain genome integrity in mammalian cells.
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Affiliation(s)
- Commodore St Germain
- School of Mathematics and Science, Solano Community College, 4000 Suisun Valley Road, Fairfield, CA 94534, USA
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
| | - Hongchang Zhao
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
| | - Jacqueline H. Barlow
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
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25
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Brossas C, Duriez B, Valton AL, Prioleau MN. Promoters are key organizers of the duplication of vertebrate genomes. Bioessays 2021; 43:e2100141. [PMID: 34319621 DOI: 10.1002/bies.202100141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/13/2021] [Accepted: 07/15/2021] [Indexed: 11/06/2022]
Abstract
In vertebrates, single cell analyses of replication timing patterns brought to light a very well controlled program suggesting a tight regulation on initiation sites. Mapping of replication origins with different methods has revealed discrete preferential sites, enriched in promoters and potential G-quadruplex motifs, which can aggregate into initiation zones spanning several tens of kilobases (kb). Another characteristic of replication origins is a nucleosome-free region (NFR). A modified yeast strain containing a humanized origin recognition complex (ORC) fires new origins at NFRs revealing their regulatory role. In cooperation with NFRs, the histone variant H2A.Z facilitates ORC loading through di-methylation of lysine 20 of histone H4. Recent studies using genome editing methods show that efficient initiation sites associated with transcriptional activity can synergize over several tens of kb by establishing physical contacts and lead to the formation of early domains of DNA replication demonstrating a co-regulation between replication initiation and transcription.
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Affiliation(s)
- Caroline Brossas
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Bénédicte Duriez
- IMRB, INSERM U955, Equipe GEIC2O, Faculté de Santé, Créteil, France
| | - Anne-Laure Valton
- Department of Biochemistry and Molecular Pharmacology, Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.,Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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26
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Blin M, Lacroix L, Petryk N, Jaszczyszyn Y, Chen CL, Hyrien O, Le Tallec B. DNA molecular combing-based replication fork directionality profiling. Nucleic Acids Res 2021; 49:e69. [PMID: 33836085 PMCID: PMC8266662 DOI: 10.1093/nar/gkab219] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/15/2021] [Accepted: 03/19/2021] [Indexed: 01/05/2023] Open
Abstract
The replication strategy of metazoan genomes is still unclear, mainly because definitive maps of replication origins are missing. High-throughput methods are based on population average and thus may exclusively identify efficient initiation sites, whereas inefficient origins go undetected. Single-molecule analyses of specific loci can detect both common and rare initiation events along the targeted regions. However, these usually concentrate on positioning individual events, which only gives an overview of the replication dynamics. Here, we computed the replication fork directionality (RFD) profiles of two large genes in different transcriptional states in chicken DT40 cells, namely untranscribed and transcribed DMD and CCSER1 expressed at WT levels or overexpressed, by aggregating hundreds of oriented replication tracks detected on individual DNA fibres stretched by molecular combing. These profiles reconstituted RFD domains composed of zones of initiation flanking a zone of termination originally observed in mammalian genomes and were highly consistent with independent population-averaging profiles generated by Okazaki fragment sequencing. Importantly, we demonstrate that inefficient origins do not appear as detectable RFD shifts, explaining why dispersed initiation has remained invisible to population-based assays. Our method can both generate quantitative profiles and identify discrete events, thereby constituting a comprehensive approach to study metazoan genome replication.
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Affiliation(s)
- Marion Blin
- Département de Gastro-entérologie, pôle MAD, Assistance Publique des Hôpitaux de Marseille, Centre Hospitalier Universitaire de Marseille, Marseille, France
| | - Laurent Lacroix
- Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, Université PSL, 46 rue d’Ulm, F-75005 Paris, France
| | - Nataliya Petryk
- Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, Université PSL, 46 rue d’Ulm, F-75005 Paris, France
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91198 Gif-sur-Yvette, France
| | - Yan Jaszczyszyn
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), F-91198 Gif-sur-Yvette, France
| | - Chun-Long Chen
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR3244, F-75005 Paris, France
| | - Olivier Hyrien
- Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, Université PSL, 46 rue d’Ulm, F-75005 Paris, France
| | - Benoît Le Tallec
- Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, Université PSL, 46 rue d’Ulm, F-75005 Paris, France
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27
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The γ-tubulin meshwork assists in the recruitment of PCNA to chromatin in mammalian cells. Commun Biol 2021; 4:767. [PMID: 34158617 PMCID: PMC8219688 DOI: 10.1038/s42003-021-02280-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 05/28/2021] [Indexed: 12/27/2022] Open
Abstract
Changes in the location of γ-tubulin ensure cell survival and preserve genome integrity. We investigated whether the nuclear accumulation of γ-tubulin facilitates the transport of proliferating cell nuclear antigen (PCNA) between the cytosolic and the nuclear compartment in mammalian cells. We found that the γ-tubulin meshwork assists in the recruitment of PCNA to chromatin. Also, decreased levels of γ-tubulin reduce the nuclear pool of PCNA. In addition, the γ-tubulin C terminus encodes a PCNA-interacting peptide (PIP) motif, and a γ-tubulin–PIP-mutant affects the nuclear accumulation of PCNA. In a cell-free system, PCNA and γ-tubulin formed a complex. In tumors, there is a significant positive correlation between TUBG1 and PCNA expression. Thus, we report a novel mechanism that constitutes the basis for tumor growth by which the γ-tubulin meshwork maintains indefinite proliferation by acting as an opportune scaffold for the transport of PCNA from the cytosol to the chromatin. Corvaisier et al discover that γ-tubulin and replication protein PCNA forms a complex and that this facilitates recruitment of PCNA to chromatin both during cell division and during the DSB repair response. They identify a PCNA binding motif in γ-tubulin, which when mutated affects replication fork progression, providing insights into the role of the nuclear γ-tubulin meshwork.
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28
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Replication initiation: Implications in genome integrity. DNA Repair (Amst) 2021; 103:103131. [PMID: 33992866 DOI: 10.1016/j.dnarep.2021.103131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 02/01/2023]
Abstract
In every cell cycle, billions of nucleotides need to be duplicated within hours, with extraordinary precision and accuracy. The molecular mechanism by which cells regulate the replication event is very complicated, and the entire process begins way before the onset of S phase. During the G1 phase of the cell cycle, cells prepare by assembling essential replication factors to establish the pre-replicative complex at origins, sites that dictate where replication would initiate during S phase. During S phase, the replication process is tightly coupled with the DNA repair system to ensure the fidelity of replication. Defects in replication and any error must be recognized by DNA damage response and checkpoint signaling pathways in order to halt the cell cycle before cells are allowed to divide. The coordination of these processes throughout the cell cycle is therefore critical to achieve genomic integrity and prevent diseases. In this review, we focus on the current understanding of how the replication initiation events are regulated to achieve genome stability.
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29
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Kumagai A, Dunphy WG. Binding of the Treslin-MTBP Complex to Specific Regions of the Human Genome Promotes the Initiation of DNA Replication. Cell Rep 2021; 32:108178. [PMID: 32966791 PMCID: PMC7523632 DOI: 10.1016/j.celrep.2020.108178] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/12/2020] [Accepted: 08/31/2020] [Indexed: 12/16/2022] Open
Abstract
The processes that control where higher eukaryotic cells initiate DNA replication throughout the genome are not understood clearly. In metazoans, the Treslin-MTBP complex mediates critical final steps in formation of the activated replicative helicase prior to initiation of replication. Here, we map the genome-wide distribution of the MTBP subunit of this complex in human cells. Our results indicate that MTBP binds to at least 30,000 sites in the genome. A majority of these sites reside in regions of open chromatin that contain transcriptional-regulatory elements (e.g., promoters, enhancers, and super-enhancers), which are known to be preferred areas for initiation of replication. Furthermore, many binding sites encompass two genomic features: a nucleosome-free DNA sequence (e.g., G-quadruplex DNA or AP-1 motif) and a nucleosome bearing histone marks characteristic of open chromatin, such as H3K4me2. Taken together, these findings indicate that Treslin-MTBP associates coordinately with multiple genomic signals to promote initiation of replication. Kumagai and Dunphy show that Treslin-MTBP, activator of the replicative helicase, binds to at least 30,000 sites in the human genome. Many sites contain a nucleosome with active chromatin marks and nucleosome-free DNA (G-quadruplex or AP-1 site). Thus, Treslin-MTBP associates with multiple genomic elements to promote initiation of DNA replication.
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Affiliation(s)
- Akiko Kumagai
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - William G Dunphy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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30
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Investigation of the Interaction of Human Origin Recognition Complex Subunit 1 with G-Quadruplex DNAs of Human c-myc Promoter and Telomere Regions. Int J Mol Sci 2021; 22:ijms22073481. [PMID: 33801762 PMCID: PMC8036949 DOI: 10.3390/ijms22073481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/19/2021] [Accepted: 03/23/2021] [Indexed: 12/15/2022] Open
Abstract
Origin recognition complex (ORC) binds to replication origins in eukaryotic DNAs and plays an important role in replication. Although yeast ORC is known to sequence-specifically bind to a replication origin, how human ORC recognizes a replication origin remains unknown. Previous genome-wide studies revealed that guanine (G)-rich sequences, potentially forming G-quadruplex (G4) structures, are present in most replication origins in human cells. We previously suggested that the region comprising residues 413–511 of human ORC subunit 1, hORC1413–511, binds preferentially to G-rich DNAs, which form a G4 structure in the absence of hORC1413–511. Here, we investigated the interaction of hORC1413-511 with various G-rich DNAs derived from human c-myc promoter and telomere regions. Fluorescence anisotropy revealed that hORC1413–511 binds preferentially to DNAs that have G4 structures over ones having double-stranded structures. Importantly, circular dichroism (CD) and nuclear magnetic resonance (NMR) showed that those G-rich DNAs retain the G4 structures even after binding with hORC1413–511. NMR chemical shift perturbation analyses revealed that the external G-tetrad planes of the G4 structures are the primary binding sites for hORC1413–511. The present study suggests that human ORC1 may recognize replication origins through the G4 structure.
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31
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Kirstein N, Buschle A, Wu X, Krebs S, Blum H, Kremmer E, Vorberg IM, Hammerschmidt W, Lacroix L, Hyrien O, Audit B, Schepers A. Human ORC/MCM density is low in active genes and correlates with replication time but does not delimit initiation zones. eLife 2021; 10:62161. [PMID: 33683199 PMCID: PMC7993996 DOI: 10.7554/elife.62161] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 03/05/2021] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic DNA replication initiates during S phase from origins that have been licensed in the preceding G1 phase. Here, we compare ChIP-seq profiles of the licensing factors Orc2, Orc3, Mcm3, and Mcm7 with gene expression, replication timing, and fork directionality profiles obtained by RNA-seq, Repli-seq, and OK-seq. Both, the origin recognition complex (ORC) and the minichromosome maintenance complex (MCM) are significantly and homogeneously depleted from transcribed genes, enriched at gene promoters, and more abundant in early- than in late-replicating domains. Surprisingly, after controlling these variables, no difference in ORC/MCM density is detected between initiation zones, termination zones, unidirectionally replicating regions, and randomly replicating regions. Therefore, ORC/MCM density correlates with replication timing but does not solely regulate the probability of replication initiation. Interestingly, H4K20me3, a histone modification proposed to facilitate late origin licensing, was enriched in late-replicating initiation zones and gene deserts of stochastic replication fork direction. We discuss potential mechanisms specifying when and where replication initiates in human cells.
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Affiliation(s)
- Nina Kirstein
- Research Unit Gene Vectors, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, Munich, Germany
| | - Alexander Buschle
- Research Unit Gene Vectors, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health and German Center for Infection Research (DZIF), Munich, Germany
| | - Xia Wu
- Institut de Biologie de l'ENS (IBENS), Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Stefan Krebs
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center of the Ludwig-Maximilians Universität (LMU) München, Munich, Germany
| | - Helmut Blum
- Laboratory for Functional Genome Analysis (LAFUGA), Gene Center of the Ludwig-Maximilians Universität (LMU) München, Munich, Germany
| | - Elisabeth Kremmer
- Institute for Molecular Immunology, Monoclonal Antibody Core Facility, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Ina M Vorberg
- German Center for Neurodegenerative Diseases (DZNE e.V.), Bonn, Germany.,Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Wolfgang Hammerschmidt
- Research Unit Gene Vectors, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health and German Center for Infection Research (DZIF), Munich, Germany
| | - Laurent Lacroix
- Institut de Biologie de l'ENS (IBENS), Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Olivier Hyrien
- Institut de Biologie de l'ENS (IBENS), Département de Biologie, Ecole Normale Supérieure, CNRS, Inserm, PSL Research University, Paris, France
| | - Benjamin Audit
- Univ Lyon, ENS de Lyon, Univ. Claude Bernard, CNRS, Laboratoire de Physique, 69342 Lyon, France
| | - Aloys Schepers
- Research Unit Gene Vectors, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, Munich, Germany
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32
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Wang J, Rojas P, Mao J, Mustè Sadurnì M, Garnier O, Xiao S, Higgs MR, Garcia P, Saponaro M. Persistence of RNA transcription during DNA replication delays duplication of transcription start sites until G2/M. Cell Rep 2021; 34:108759. [PMID: 33596418 PMCID: PMC7900609 DOI: 10.1016/j.celrep.2021.108759] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 11/09/2020] [Accepted: 01/26/2021] [Indexed: 12/22/2022] Open
Abstract
As transcription and replication use DNA as substrate, conflicts between transcription and replication can occur, leading to genome instability with direct consequences for human health. To determine how the two processes are coordinated throughout S phase, we characterize both processes together at high resolution. We find that transcription occurs during DNA replication, with transcription start sites (TSSs) not fully replicated along with surrounding regions and remaining under-replicated until late in the cell cycle. TSSs undergo completion of DNA replication specifically when cells enter mitosis, when RNA polymerase II is removed. Intriguingly, G2/M DNA synthesis occurs at high frequency in unperturbed cell culture, but it is not associated with increased DNA damage and is fundamentally separated from mitotic DNA synthesis. TSSs duplicated in G2/M are characterized by a series of specific features, including high levels of antisense transcription, making them difficult to duplicate during S phase.
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Affiliation(s)
- Jianming Wang
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Patricia Rojas
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Jingwen Mao
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Martina Mustè Sadurnì
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Olivia Garnier
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Songshu Xiao
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Martin R Higgs
- Lysine Methylation and DNA Damage Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Paloma Garcia
- Stem Cells and Genome Stability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Marco Saponaro
- Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK.
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33
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Akerman I, Kasaai B, Bazarova A, Sang PB, Peiffer I, Artufel M, Derelle R, Smith G, Rodriguez-Martinez M, Romano M, Kinet S, Tino P, Theillet C, Taylor N, Ballester B, Méchali M. A predictable conserved DNA base composition signature defines human core DNA replication origins. Nat Commun 2020; 11:4826. [PMID: 32958757 PMCID: PMC7506530 DOI: 10.1038/s41467-020-18527-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/18/2020] [Indexed: 02/06/2023] Open
Abstract
DNA replication initiates from multiple genomic locations called replication origins. In metazoa, DNA sequence elements involved in origin specification remain elusive. Here, we examine pluripotent, primary, differentiating, and immortalized human cells, and demonstrate that a class of origins, termed core origins, is shared by different cell types and host ~80% of all DNA replication initiation events in any cell population. We detect a shared G-rich DNA sequence signature that coincides with most core origins in both human and mouse genomes. Transcription and G-rich elements can independently associate with replication origin activity. Computational algorithms show that core origins can be predicted, based solely on DNA sequence patterns but not on consensus motifs. Our results demonstrate that, despite an attributed stochasticity, core origins are chosen from a limited pool of genomic regions. Immortalization through oncogenic gene expression, but not normal cellular differentiation, results in increased stochastic firing from heterochromatin and decreased origin density at TAD borders. In metazoan the DNA sequence elements characterizing origin specification are unknown. By generating and analysing 19 SNS-seq datasets from different human cell types, the authors reveal a class and features of Core origins of replication which can be predicted by an algorithm.
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Affiliation(s)
- Ildem Akerman
- Institute of Human Genetics, CNRS - University of Montpellier, Montpellier, France. .,Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.
| | - Bahar Kasaai
- Institute of Human Genetics, CNRS - University of Montpellier, Montpellier, France
| | - Alina Bazarova
- Centre for Computational Biology (CCB), University of Birmingham, Birmingham, UK.,Institute for Biological Physics, University of Cologne, Cologne, Germany
| | - Pau Biak Sang
- Institute of Human Genetics, CNRS - University of Montpellier, Montpellier, France
| | - Isabelle Peiffer
- Institute of Human Genetics, CNRS - University of Montpellier, Montpellier, France
| | - Marie Artufel
- Aix-Marseille University, INSERM, TAGC, UMR S1090, Marseille, France
| | - Romain Derelle
- Life and Environmental Sciences (LES), University of Birmingham, Birmingham, UK
| | - Gabrielle Smith
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
| | | | - Manuela Romano
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Sandrina Kinet
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France
| | - Peter Tino
- Centre for Computational Biology (CCB), University of Birmingham, Birmingham, UK
| | - Charles Theillet
- Institut de Recherche en Cancérologie de Montpellier (IRCM), Montpellier, France
| | - Naomi Taylor
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France.,Pediatric Oncology Branch, NCI, CCR, NIH, Bethesda, MD, USA
| | - Benoit Ballester
- Aix-Marseille University, INSERM, TAGC, UMR S1090, Marseille, France
| | - Marcel Méchali
- Institute of Human Genetics, CNRS - University of Montpellier, Montpellier, France.
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34
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Kaposi's Sarcoma-Associated Herpesvirus Lytic Replication Is Independent of Anaphase-Promoting Complex Activity. J Virol 2020; 94:JVI.02079-19. [PMID: 32295923 PMCID: PMC7307157 DOI: 10.1128/jvi.02079-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 04/12/2020] [Indexed: 11/20/2022] Open
Abstract
The anaphase-promoting complex, or cyclosome (APC/C), is a large E3 ubiquitin ligase composed of 14 subunits. The activity of APC/C oscillates during the cell cycle to ensure a timely transition through each phase by promoting the degradation of important cell cycle regulators. Of the human herpesviruses, cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) both impair the activity of APC/C during their lytic replication cycle through virus-encoded protein kinases. Here, we addressed whether the oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV) deregulates the activity of APC/C during the lytic replication cycle. To this end, we used the well-characterized iSLK.219 cell model of KSHV infection and established a new infection model of primary lymphatic endothelial cells (LECs) infected with a lytically replicating KSHV BAC16 mutant. In contrast to those of EBV and HCMV, the KSHV lytic cycle occurs while the APC/C is active. Moreover, interfering with the activity of APC/C did not lead to major changes in the production of infectious virus. We further investigated whether rereplication stress induced by the unscheduled activation of the APC/C-CDH1 complex affects the number and integrity of KSHV viral episomes. Deep sequencing of the viral episomes and host chromosomes in iSLK.219 cells revealed that, while distinct regions in the cellular chromosomes were severely affected by rereplication stress, the integrity of the viral episomes remained unaltered.IMPORTANCE DNA viruses have evolved complex strategies to gain control over the cell cycle. Several of them target APC/C, a key cellular machinery that controls the timely progression of the cell cycle, by either blocking or enhancing its activity. Here, we investigated the activity of APC/C during the lytic replication cycle of KSHV and found that, in contrast to that of KSHV's close relatives EBV and HCMV, KSHV lytic replication occurs while the APC/C is active. Perturbing APC/C activity by depleting a core protein or the adaptor proteins of the catalytic domain, and hence interfering with normal cell-cycle progression, did not affect virus replication. This suggests that KSHV has evolved to replicate independently of the activity of APC/C and in various cell cycle conditions.
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35
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Abstract
Common fragile sites (CFSs) are large chromosomal regions that exhibit breakage on metaphase chromosomes upon replication stress. They become preferentially unstable at the early stage of cancer development and are hotspots for chromosomal rearrangements in cancers. Increasing evidence has highlighted the complexity underlying the instability of CFSs, and a combination of multiple mechanisms is believed to cause CFS fragility. We will review recent advancements in our understanding of the molecular mechanisms underlying the maintenance of CFS stability and the relevance of CFSs to cancer-associated genome instability. We will emphasize the contribution of the structure-prone AT-rich sequences to CFS instability, which is in line with the recent genome-wide study showing that structure-forming repeat sequences are principal sites of replication stress.
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Affiliation(s)
- Shibo Li
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA 92037 USA
| | - Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA 92037 USA
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36
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Hulke ML, Massey DJ, Koren A. Genomic methods for measuring DNA replication dynamics. Chromosome Res 2020; 28:49-67. [PMID: 31848781 PMCID: PMC7131883 DOI: 10.1007/s10577-019-09624-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/30/2019] [Accepted: 12/03/2019] [Indexed: 12/27/2022]
Abstract
Genomic DNA replicates according to a defined temporal program in which early-replicating loci are associated with open chromatin, higher gene density, and increased gene expression levels, while late-replicating loci tend to be heterochromatic and show higher rates of genomic instability. The ability to measure DNA replication dynamics at genome scale has proven crucial for understanding the mechanisms and cellular consequences of DNA replication timing. Several methods, such as quantification of nucleotide analog incorporation and DNA copy number analyses, can accurately reconstruct the genomic replication timing profiles of various species and cell types. More recent developments have expanded the DNA replication genomic toolkit to assays that directly measure the activity of replication origins, while single-cell replication timing assays are beginning to reveal a new level of replication timing regulation. The combination of these methods, applied on a genomic scale and in multiple biological systems, promises to resolve many open questions and lead to a holistic understanding of how eukaryotic cells replicate their genomes accurately and efficiently.
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Affiliation(s)
- Michelle L Hulke
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Dashiell J Massey
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
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37
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Transcription-mediated organization of the replication initiation program across large genes sets common fragile sites genome-wide. Nat Commun 2019; 10:5693. [PMID: 31836700 PMCID: PMC6911102 DOI: 10.1038/s41467-019-13674-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 11/15/2019] [Indexed: 12/29/2022] Open
Abstract
Common fragile sites (CFSs) are chromosome regions prone to breakage upon replication stress known to drive chromosome rearrangements during oncogenesis. Most CFSs nest in large expressed genes, suggesting that transcription could elicit their instability; however, the underlying mechanisms remain elusive. Genome-wide replication timing analyses here show that stress-induced delayed/under-replication is the hallmark of CFSs. Extensive genome-wide analyses of nascent transcripts, replication origin positioning and fork directionality reveal that 80% of CFSs nest in large transcribed domains poor in initiation events, replicated by long-travelling forks. Forks that travel long in late S phase explains CFS replication features, whereas formation of sequence-dependent fork barriers or head-on transcription–replication conflicts do not. We further show that transcription inhibition during S phase, which suppresses transcription–replication encounters and prevents origin resetting, could not rescue CFS stability. Altogether, our results show that transcription-dependent suppression of initiation events delays replication of large gene bodies, committing them to instability. Common Fragile Sites (CFSs) are chromosome regions prone to breakage upon replication stress known to drive chromosome rearrangements during oncogenesis. Here the authors use genome-wide and single cell techniques to assess how replication timing and transcriptional activity correlate with genome stability.
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38
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Massip F, Laurent M, Brossas C, Fernández-Justel JM, Gómez M, Prioleau MN, Duret L, Picard F. Evolution of replication origins in vertebrate genomes: rapid turnover despite selective constraints. Nucleic Acids Res 2019; 47:5114-5125. [PMID: 30916335 PMCID: PMC6547456 DOI: 10.1093/nar/gkz182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 02/28/2019] [Accepted: 03/11/2019] [Indexed: 01/03/2023] Open
Abstract
The replication program of vertebrate genomes is driven by the chromosomal distribution and timing of activation of tens of thousands of replication origins. Genome-wide studies have shown the association of origins with promoters and CpG islands, and their enrichment in G-quadruplex motifs (G4). However, the genetic determinants driving their activity remain poorly understood. To gain insight on the constraints operating on origins, we conducted the first evolutionary comparison of origins across vertebrates. We generated a genome-wide map of chicken origins (the first of a bird genome), and performed a comparison with human and mouse maps. The analysis of intra-species polymorphism revealed a strong depletion of genetic diversity at the core of replication initiation loci. This depletion is not linked to the presence of G4 motifs, promoters or CpG islands. In contrast, we show that origins experienced a rapid turnover during vertebrate evolution, since pairwise comparisons of origin maps revealed that <24% of them are conserved among vertebrates. This study unravels the existence of a novel determinant of origins, the precise functional role of which remains to be determined. Despite the importance of replication initiation for the fitness of organisms, the distribution of origins along vertebrate chromosomes is highly flexible.
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Affiliation(s)
- Florian Massip
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, Villleurbanne, France.,Berlin Institute for Medical Systems Biology, Max Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Marc Laurent
- Institut Jacques Monod, CNRS UMR7592, Université Paris Diderot, Equipe Labellisée Association pour la Recherche sur le Cancer, Paris, France
| | - Caroline Brossas
- Institut Jacques Monod, CNRS UMR7592, Université Paris Diderot, Equipe Labellisée Association pour la Recherche sur le Cancer, Paris, France
| | | | - María Gómez
- Centro de Biología Molecular Severo Ochoa CBMSO (CSIC/UAM). Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Marie-Noelle Prioleau
- Institut Jacques Monod, CNRS UMR7592, Université Paris Diderot, Equipe Labellisée Association pour la Recherche sur le Cancer, Paris, France
| | - Laurent Duret
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, Villleurbanne, France
| | - Franck Picard
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, Villleurbanne, France
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39
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Limas JC, Cook JG. Preparation for DNA replication: the key to a successful S phase. FEBS Lett 2019; 593:2853-2867. [PMID: 31556113 PMCID: PMC6817399 DOI: 10.1002/1873-3468.13619] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/09/2019] [Accepted: 09/17/2019] [Indexed: 12/13/2022]
Abstract
Successful genome duplication is required for cell proliferation and demands extraordinary precision and accuracy. The mechanisms by which cells enter, progress through, and exit S phase are intense areas of focus in the cell cycle and genome stability fields. Key molecular events in the G1 phase of the cell division cycle, especially origin licensing, are essential for pre-establishing conditions for efficient DNA replication during the subsequent S phase. If G1 events are poorly regulated or disordered, then DNA replication can be compromised leading to genome instability, a hallmark of tumorigenesis. Upon entry into S phase, coordinated origin firing and replication progression ensure complete, timely, and precise chromosome replication. Both G1 and S phase progressions are controlled by master cell cycle protein kinases and ubiquitin ligases that govern the activity and abundance of DNA replication factors. In this short review, we describe current understanding and recent developments related to G1 progression and S phase entrance and exit with a particular focus on origin licensing regulation in vertebrates.
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Affiliation(s)
- Juanita C Limas
- Department of Pharmacology, University of North Carolina at Chapel Hill, NC, USA
| | - Jeanette Gowen Cook
- Department of Pharmacology, University of North Carolina at Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, NC, USA
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40
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Bryan TM. Mechanisms of DNA Replication and Repair: Insights from the Study of G-Quadruplexes. Molecules 2019; 24:E3439. [PMID: 31546714 PMCID: PMC6804030 DOI: 10.3390/molecules24193439] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/18/2019] [Accepted: 09/18/2019] [Indexed: 12/13/2022] Open
Abstract
G-quadruplexes are four-stranded guanine-rich structures that have been demonstrated to occur across the genome in humans and other organisms. They provide regulatory functions during transcription, translation and immunoglobulin gene rearrangement, but there is also a large amount of evidence that they can present a potent barrier to the DNA replication machinery. This mini-review will summarize recent advances in understanding the many strategies nature has evolved to overcome G-quadruplex-mediated replication blockage, including removal of the structure by helicases or nucleases, or circumventing the deleterious effects on the genome through homologous recombination, alternative end-joining or synthesis re-priming. Paradoxically, G-quadruplexes have also recently been demonstrated to provide a positive role in stimulating the initiation of DNA replication. These recent studies have not only illuminated the many roles and consequences of G-quadruplexes, but have also provided fundamental insights into the general mechanisms of DNA replication and its links with genetic and epigenetic stability.
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Affiliation(s)
- Tracy M Bryan
- Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia.
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41
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Casar Tena T, Maerz LD, Szafranski K, Groth M, Blätte TJ, Donow C, Matysik S, Walther P, Jeggo PA, Burkhalter MD, Philipp M. Resting cells rely on the DNA helicase component MCM2 to build cilia. Nucleic Acids Res 2019; 47:134-151. [PMID: 30329080 PMCID: PMC6326816 DOI: 10.1093/nar/gky945] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Accepted: 10/04/2018] [Indexed: 12/24/2022] Open
Abstract
Minichromosome maintenance (MCM) proteins facilitate replication by licensing origins and unwinding the DNA double strand. Interestingly, the number of MCM hexamers greatly exceeds the number of firing origins suggesting additional roles of MCMs. Here we show a hitherto unanticipated function of MCM2 in cilia formation in human cells and zebrafish that is uncoupled from replication. Zebrafish depleted of MCM2 develop ciliopathy-phenotypes including microcephaly and aberrant heart looping due to malformed cilia. In non-cycling human fibroblasts, loss of MCM2 promotes transcription of a subset of genes, which cause cilia shortening and centriole overduplication. Chromatin immunoprecipitation experiments show that MCM2 binds to transcription start sites of cilia inhibiting genes. We propose that such binding may block RNA polymerase II-mediated transcription. Depletion of a second MCM (MCM7), which functions in complex with MCM2 during its canonical functions, reveals an overlapping cilia-deficiency phenotype likely unconnected to replication, although MCM7 appears to regulate a distinct subset of genes and pathways. Our data suggests that MCM2 and 7 exert a role in ciliogenesis in post-mitotic tissues.
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Affiliation(s)
- Teresa Casar Tena
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Lars D Maerz
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Karol Szafranski
- Leibniz Institute on Aging, Fritz Lipmann Institute, 07745 Jena, Germany
| | - Marco Groth
- Leibniz Institute on Aging, Fritz Lipmann Institute, 07745 Jena, Germany
| | - Tamara J Blätte
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Cornelia Donow
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Sabrina Matysik
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, 89081 Ulm, Germany
| | - Penelope A Jeggo
- Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK
| | - Martin D Burkhalter
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
| | - Melanie Philipp
- Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
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42
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Prorok P, Artufel M, Aze A, Coulombe P, Peiffer I, Lacroix L, Guédin A, Mergny JL, Damaschke J, Schepers A, Cayrou C, Teulade-Fichou MP, Ballester B, Méchali M. Involvement of G-quadruplex regions in mammalian replication origin activity. Nat Commun 2019; 10:3274. [PMID: 31332171 PMCID: PMC6646384 DOI: 10.1038/s41467-019-11104-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/08/2019] [Indexed: 12/11/2022] Open
Abstract
Genome-wide studies of DNA replication origins revealed that origins preferentially associate with an Origin G-rich Repeated Element (OGRE), potentially forming G-quadruplexes (G4). Here, we functionally address their requirements for DNA replication initiation in a series of independent approaches. Deletion of the OGRE/G4 sequence strongly decreased the corresponding origin activity. Conversely, the insertion of an OGRE/G4 element created a new replication origin. This element also promoted replication of episomal EBV vectors lacking the viral origin, but not if the OGRE/G4 sequence was deleted. A potent G4 ligand, PhenDC3, stabilized G4s but did not alter the global origin activity. However, a set of new, G4-associated origins was created, whereas suppressed origins were largely G4-free. In vitro Xenopus laevis replication systems showed that OGRE/G4 sequences are involved in the activation of DNA replication, but not in the pre-replication complex formation. Altogether, these results converge to the functional importance of OGRE/G4 elements in DNA replication initiation.
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Affiliation(s)
- Paulina Prorok
- Institute of Human Genetics, CNRS-University of Montpellier, 141 rue de la Cardonille, 34396, Montpellier, France
| | | | - Antoine Aze
- Institute of Human Genetics, CNRS-University of Montpellier, 141 rue de la Cardonille, 34396, Montpellier, France
| | - Philippe Coulombe
- Institute of Human Genetics, CNRS-University of Montpellier, 141 rue de la Cardonille, 34396, Montpellier, France
| | - Isabelle Peiffer
- Institute of Human Genetics, CNRS-University of Montpellier, 141 rue de la Cardonille, 34396, Montpellier, France
| | - Laurent Lacroix
- Balasubramanian group, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Aurore Guédin
- ARNA Laboratory, Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie Biologie (IECB), Pessac, 33607, France
| | - Jean-Louis Mergny
- ARNA Laboratory, Université de Bordeaux, Inserm U1212, CNRS UMR5320, Institut Européen de Chimie Biologie (IECB), Pessac, 33607, France.,Institut Curie, CNRS UMR9187, Inserm U1196, Universite Paris Saclay, Orsay, France
| | - Julia Damaschke
- Research Unit Gene Vectors, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, Marchioninistraße 25, 81377, Munich, Germany
| | - Aloys Schepers
- Research Unit Gene Vectors, Helmholtz Zentrum München (GmbH), German Research Center for Environmental Health, Marchioninistraße 25, 81377, Munich, Germany.,Monoclonal Antibody Core Facility & Research Group, Institute for Diabetes and Obesity, Helmholtz Zentrum München, Ingolstädter Landstrasse, 85764, Neuherberg, Germany
| | - Christelle Cayrou
- Institute of Human Genetics, CNRS-University of Montpellier, 141 rue de la Cardonille, 34396, Montpellier, France.,Centre de Recherche en Cancérologie de Marseille 27 Boulevard Lei Roure, 13273, Marseille, France
| | | | | | - Marcel Méchali
- Institute of Human Genetics, CNRS-University of Montpellier, 141 rue de la Cardonille, 34396, Montpellier, France.
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43
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Abstract
DNA replication starts with the opening of DNA at sites called DNA replication origins. From the single sequence-specific DNA replication origin of the small Escherichia coli genome, up to thousands of origins that are necessary to replicate the large human genome, strict sequence specificity has been lost. Nevertheless, genome-wide analyses performed in the recent years, using different mapping methods, demonstrated that there are precise locations along the metazoan genome from which replication initiates. These sites contain relaxed sequence consensus and epigenetic features. There is flexibility in the choice of origins to be used during a given cell cycle, probably imposed by evolution and developmental constraints. Here, we will briefly describe their main features.
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44
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Okamoto Y, Hejna J, Takata M. Regulation of R-loops and genome instability in Fanconi anemia. J Biochem 2019; 165:465-470. [DOI: 10.1093/jb/mvz019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/25/2019] [Indexed: 12/13/2022] Open
Affiliation(s)
- Yusuke Okamoto
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Graduate School of Biostudies, Radiation Biology Center, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, Japan
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, Japan
| | - James Hejna
- Laboratory of Science Communication, Department of Biology Education and Heredity, Graduate School of Biostudies, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Japan
| | - Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Graduate School of Biostudies, Radiation Biology Center, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, Japan
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45
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Developing Novel G-Quadruplex Ligands: from Interaction with Nucleic Acids to Interfering with Nucleic Acid⁻Protein Interaction. Molecules 2019; 24:molecules24030396. [PMID: 30678288 PMCID: PMC6384609 DOI: 10.3390/molecules24030396] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/10/2019] [Accepted: 01/22/2019] [Indexed: 12/20/2022] Open
Abstract
G-quadruplex is a special secondary structure of nucleic acids in guanine-rich sequences of genome. G-quadruplexes have been proved to be involved in the regulation of replication, DNA damage repair, and transcription and translation of oncogenes or other cancer-related genes. Therefore, targeting G-quadruplexes has become a novel promising anti-tumor strategy. Different kinds of small molecules targeting the G-quadruplexes have been designed, synthesized, and identified as potential anti-tumor agents, including molecules directly bind to the G-quadruplex and molecules interfering with the binding between the G-quadruplex structures and related binding proteins. This review will explore the feasibility of G-quadruplex ligands acting as anti-tumor drugs, from basis to application. Meanwhile, since helicase is the most well-defined G-quadruplex-related protein, the most extensive research on the relationship between helicase and G-quadruplexes, and its meaning in drug design, is emphasized.
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46
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Transcription-dependent regulation of replication dynamics modulates genome stability. Nat Struct Mol Biol 2018; 26:58-66. [PMID: 30598553 DOI: 10.1038/s41594-018-0170-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 11/16/2018] [Indexed: 01/17/2023]
Abstract
Common fragile sites (CFSs) are loci that are hypersensitive to replication stress and hotspots for chromosomal rearrangements in cancers. CFSs replicate late in S phase, are cell-type specific and nest in large genes. The relative impact of transcription-replication conflicts versus a low density in initiation events on fragility is currently debated. Here we addressed the relationships between transcription, replication, and instability by manipulating the transcription of endogenous large genes in chicken and human cells. We found that inducing low transcription with a weak promoter destabilized large genes, whereas stimulating their transcription with strong promoters alleviated instability. Notably, strong promoters triggered a switch to an earlier replication timing, supporting a model in which high transcription levels give cells more time to complete replication before mitosis. Transcription could therefore contribute to maintaining genome integrity, challenging the dominant view that it is exclusively a threat.
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47
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Irony-Tur Sinai M, Kerem B. Genomic instability in fragile sites-still adding the pieces. Genes Chromosomes Cancer 2018; 58:295-304. [PMID: 30525255 DOI: 10.1002/gcc.22715] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 12/19/2022] Open
Abstract
Common fragile sites (CFSs) are specific genomic regions in normal chromosomes that exhibit genomic instability under DNA replication stress. As replication stress is an early feature of cancer development, CFSs are involved in the signature of genomic instability found in malignant tumors. The landscape of CFSs is tissue-specific and differs under different replication stress inducers. Nevertheless, the features underlying CFS sensitivity to replication stress are shared. Here, we review the events generating replication stress and discuss the unique characteristics of CFS regions and the cellular responses aimed to stabilizing these regions.
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Affiliation(s)
- Michal Irony-Tur Sinai
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
| | - Batsheva Kerem
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
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48
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Bouwman BAM, Crosetto N. Endogenous DNA Double-Strand Breaks during DNA Transactions: Emerging Insights and Methods for Genome-Wide Profiling. Genes (Basel) 2018; 9:E632. [PMID: 30558210 PMCID: PMC6316733 DOI: 10.3390/genes9120632] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/11/2018] [Accepted: 12/12/2018] [Indexed: 02/07/2023] Open
Abstract
DNA double-strand breaks (DSBs) jeopardize genome integrity and can-when repaired unfaithfully-give rise to structural rearrangements associated with cancer. Exogenous agents such as ionizing radiation or chemotherapy can invoke DSBs, but a vast amount of breakage arises during vital endogenous DNA transactions, such as replication and transcription. Additionally, chromatin looping involved in 3D genome organization and gene regulation is increasingly recognized as a possible contributor to DSB events. In this review, we first discuss insights into the mechanisms of endogenous DSB formation, showcasing the trade-off between essential DNA transactions and the intrinsic challenges that these processes impose on genomic integrity. In the second part, we highlight emerging methods for genome-wide profiling of DSBs, and discuss future directions of research that will help advance our understanding of genome-wide DSB formation and repair.
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Affiliation(s)
- Britta A M Bouwman
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17165 Stockholm, Sweden.
| | - Nicola Crosetto
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17165 Stockholm, Sweden.
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Courtot L, Hoffmann JS, Bergoglio V. The Protective Role of Dormant Origins in Response to Replicative Stress. Int J Mol Sci 2018; 19:ijms19113569. [PMID: 30424570 PMCID: PMC6274952 DOI: 10.3390/ijms19113569] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/05/2018] [Accepted: 11/07/2018] [Indexed: 02/07/2023] Open
Abstract
Genome stability requires tight regulation of DNA replication to ensure that the entire genome of the cell is duplicated once and only once per cell cycle. In mammalian cells, origin activation is controlled in space and time by a cell-specific and robust program called replication timing. About 100,000 potential replication origins form on the chromatin in the gap 1 (G1) phase but only 20⁻30% of them are active during the DNA replication of a given cell in the synthesis (S) phase. When the progress of replication forks is slowed by exogenous or endogenous impediments, the cell must activate some of the inactive or "dormant" origins to complete replication on time. Thus, the many origins that may be activated are probably key to protect the genome against replication stress. This review aims to discuss the role of these dormant origins as safeguards of the human genome during replicative stress.
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Affiliation(s)
- Lilas Courtot
- 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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