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Wu S, Cheng P, Yang F. Study on the impact of digital transformation on green competitive advantage: The role of green innovation and government regulation. PLoS One 2024; 19:e0306603. [PMID: 39088476 PMCID: PMC11293740 DOI: 10.1371/journal.pone.0306603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 06/20/2024] [Indexed: 08/03/2024] Open
Abstract
Digital transformation enables small and medium enterprises (SMEs) to reduce or overcome their reliance on resources and energy, thereby minimizing their environmental impact and providing them with sustainable green competitive advantages. However, the reasons for this phenomenon are not yet clear. To further investigate this issue, we selected 391 Chinese SMEs to examine the relationships among green transformation, green innovation, government regulation, and green competitive advantages. Green innovation includes green product innovation and green process innovation, while government regulation includes incentive regulation, constraint regulation, and guidance regulation. The empirical results show that digital transformation can enhance SMEs' green competitive advantages. Additionally, the hypothesized mediating effect of green product innovation and green process innovation between digital transformation and green competitive advantages is supported, while the moderating effect of incentive regulation, constraint regulation, and guidance regulation on the relationship between digital transformation and green product innovation and green process innovation is also confirmed. The findings of this study may contribute to more effective management of digital transformation and green innovation in SMEs, thereby promoting their development.
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Affiliation(s)
- Shaoling Wu
- School of Economics and Management, Hubei University of Automotive Technology, Shiyan, Hubei, China
| | - Peng Cheng
- Dongfeng Commercial Vehicle Co., Ltd, After-Market Business Division, Shiyan, Hubei, China
| | - Fan Yang
- School of Foreign Languages, Hubei University of Automotive Technology, Shiyan, Hubei, China
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2
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Chanou A, Weiβ M, Holler K, Sajid A, Straub T, Krietsch J, Sanchi A, Ummethum H, Lee CSK, Kruse E, Trauner M, Werner M, Lalonde M, Lopes M, Scialdone A, Hamperl S. Single molecule MATAC-seq reveals key determinants of DNA replication origin efficiency. Nucleic Acids Res 2023; 51:12303-12324. [PMID: 37956271 PMCID: PMC10711542 DOI: 10.1093/nar/gkad1022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 10/12/2023] [Accepted: 10/20/2023] [Indexed: 11/15/2023] Open
Abstract
Stochastic origin activation gives rise to significant cell-to-cell variability in the pattern of genome replication. The molecular basis for heterogeneity in efficiency and timing of individual origins is a long-standing question. Here, we developed Methylation Accessibility of TArgeted Chromatin domain Sequencing (MATAC-Seq) to determine single-molecule chromatin accessibility of four specific genomic loci. MATAC-Seq relies on preferential modification of accessible DNA by methyltransferases combined with Nanopore-Sequencing for direct readout of methylated DNA-bases. Applying MATAC-Seq to selected early-efficient and late-inefficient yeast replication origins revealed large heterogeneity of chromatin states. Disruption of INO80 or ISW2 chromatin remodeling complexes leads to changes at individual nucleosomal positions that correlate with changes in their replication efficiency. We found a chromatin state with an accessible nucleosome-free region in combination with well-positioned +1 and +2 nucleosomes as a strong predictor for efficient origin activation. Thus, MATAC-Seq identifies the large spectrum of alternative chromatin states that co-exist on a given locus previously masked in population-based experiments and provides a mechanistic basis for origin activation heterogeneity during eukaryotic DNA replication. Consequently, our single-molecule chromatin accessibility assay will be ideal to define single-molecule heterogeneity across many fundamental biological processes such as transcription, replication, or DNA repair in vitro and ex vivo.
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Affiliation(s)
- Anna Chanou
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Matthias Weiβ
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Karoline Holler
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Atiqa Sajid
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Tobias Straub
- Core Facility Bioinformatics, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Jana Krietsch
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Andrea Sanchi
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Henning Ummethum
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Clare S K Lee
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Elisabeth Kruse
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Manuel Trauner
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Marcel Werner
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Maxime Lalonde
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Antonio Scialdone
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Stephan Hamperl
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
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3
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Kwan EX, Alvino GM, Lynch KL, Levan PF, Amemiya HM, Wang XS, Johnson SA, Sanchez JC, Miller MA, Croy M, Lee SB, Naushab M, Bedalov A, Cuperus JT, Brewer BJ, Queitsch C, Raghuraman MK. Ribosomal DNA replication time coordinates completion of genome replication and anaphase in yeast. Cell Rep 2023; 42:112161. [PMID: 36842087 PMCID: PMC10142053 DOI: 10.1016/j.celrep.2023.112161] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 12/19/2022] [Accepted: 02/09/2023] [Indexed: 02/27/2023] Open
Abstract
Timely completion of genome replication is a prerequisite for mitosis, genome integrity, and cell survival. A challenge to this timely completion comes from the need to replicate the hundreds of untranscribed copies of rDNA that organisms maintain in addition to the copies required for ribosome biogenesis. Replication of these rDNA arrays is relegated to late S phase despite their large size, repetitive nature, and essentiality. Here, we show that, in Saccharomyces cerevisiae, reducing the number of rDNA repeats leads to early rDNA replication, which results in delaying replication elsewhere in the genome. Moreover, cells with early-replicating rDNA arrays and delayed genome-wide replication aberrantly release the mitotic phosphatase Cdc14 from the nucleolus and enter anaphase prematurely. We propose that rDNA copy number determines the replication time of the rDNA locus and that the release of Cdc14 upon completion of rDNA replication is a signal for cell cycle progression.
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Affiliation(s)
- Elizabeth X Kwan
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Gina M Alvino
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Kelsey L Lynch
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Paula F Levan
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Haley M Amemiya
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Xiaobin S Wang
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Sarah A Johnson
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Joseph C Sanchez
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Madison A Miller
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Mackenzie Croy
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Seung-Been Lee
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Maria Naushab
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Antonio Bedalov
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Bonita J Brewer
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
| | - M K Raghuraman
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
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4
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Kim JM, Visanpattanasin P, Jou V, Liu S, Tang X, Zheng Q, Li KY, Snedeker J, Lavis LD, Lionnet T, Wu C. Single-molecule imaging of chromatin remodelers reveals role of ATPase in promoting fast kinetics of target search and dissociation from chromatin. eLife 2021; 10:e69387. [PMID: 34313223 PMCID: PMC8352589 DOI: 10.7554/elife.69387] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/26/2021] [Indexed: 12/14/2022] Open
Abstract
Conserved ATP-dependent chromatin remodelers establish and maintain genome-wide chromatin architectures of regulatory DNA during cellular lifespan, but the temporal interactions between remodelers and chromatin targets have been obscure. We performed live-cell single-molecule tracking for RSC, SWI/SNF, CHD1, ISW1, ISW2, and INO80 remodeling complexes in budding yeast and detected hyperkinetic behaviors for chromatin-bound molecules that frequently transition to the free state for all complexes. Chromatin-bound remodelers display notably higher diffusion than nucleosomal histones, and strikingly fast dissociation kinetics with 4-7 s mean residence times. These enhanced dynamics require ATP binding or hydrolysis by the catalytic ATPase, uncovering an additional function to its established role in nucleosome remodeling. Kinetic simulations show that multiple remodelers can repeatedly occupy the same promoter region on a timescale of minutes, implicating an unending 'tug-of-war' that controls a temporally shifting window of accessibility for the transcription initiation machinery.
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Affiliation(s)
- Jee Min Kim
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | | | - Vivian Jou
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Sheng Liu
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Xiaona Tang
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Qinsi Zheng
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Kai Yu Li
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Jonathan Snedeker
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Timothee Lionnet
- Institute of Systems Genetics, Langone Medical Center, New York UniversityNew YorkUnited States
| | - Carl Wu
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
- Department of Molecular Biology and Genetics, Johns Hopkins School of MedicineBaltimoreUnited States
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5
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Lee PH, Osley MA. Who gets a license: DNA synthesis in quiescent cells re-entering the cell cycle. Curr Genet 2021; 67:539-543. [PMID: 33682029 DOI: 10.1007/s00294-021-01170-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 12/23/2022]
Abstract
The precise regulation of the entry into S phase is critical for preventing genome instability. The first step in the initiation of eukaryotic DNA synthesis occurs in G1 phase cells and involves the loading of the conserved MCM helicase onto multiple origins of replication in a process known as origin licensing. In proliferating metazoan cells, an origin-licensing checkpoint delays initiation until high levels of MCM loading occur, with excess origins being licensed. One function of this checkpoint is to ensure that S phase can be completed in the face of replication stress by activation of dormant MCM bound origins. However, when both metazoan and yeast cells enter S phase from quiescence or G0 phase, a non-growing but reversible cell cycle state, origins are significantly under-licensed. In metazoan cells, under-licensing is the result of a compromised origin-licensing checkpoint. In budding yeast, our study has revealed that under-licensing can be attributed to the chromatin structure at a class of origins that is inhibitory to the binding of MCM. Thus, defects in multiple pathways may contribute to the failure to fully license origins in quiescent cells re-entering the cell cycle, thereby promoting a higher risk of genome instability.
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Affiliation(s)
- Po-Hsuen Lee
- Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA
| | - Mary Ann Osley
- Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM, 87131, USA.
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6
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Talaromyces trachyspermus, an endophyte from Withania somnifera with plant growth promoting attributes. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s42398-019-00045-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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7
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Chromatin Remodeling Factors Isw2 and Ino80 Regulate Chromatin, Replication, and Copy Number of the Saccharomyces cerevisiae Ribosomal DNA Locus. Genetics 2018; 210:1543-1556. [PMID: 30355728 DOI: 10.1534/genetics.118.301579] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/17/2018] [Indexed: 01/08/2023] Open
Abstract
In the budding yeast Saccharomyces cerevisiae, ribosomal RNA genes are encoded in a highly repetitive tandem array referred to as the ribosomal DNA (rDNA) locus. The yeast rDNA is the site of a diverse set of DNA-dependent processes, including transcription of ribosomal RNAs by RNA polymerases I and III, transcription of noncoding RNAs by RNA polymerase II, DNA replication initiation, replication fork blocking, and recombination-mediated regulation of rDNA repeat copy number. All of this takes place in the context of chromatin, but little is known about the roles played by ATP-dependent chromatin remodeling factors at the yeast rDNA. In this work, we report that the Isw2 and Ino80 chromatin remodeling factors are targeted to this highly repetitive locus. We characterize for the first time their function in modifying local chromatin structure, finding that loss of these factors decreases the fraction of actively transcribed 35S ribosomal RNA genes and the positioning of nucleosomes flanking the ribosomal origin of replication. In addition, we report that Isw2 and Ino80 promote efficient firing of the ribosomal origin of replication and facilitate the regulated increase of rDNA repeat copy number. This work significantly expands our understanding of the importance of ATP-dependent chromatin remodeling for rDNA biology.
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8
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Litwin I, Bakowski T, Szakal B, Pilarczyk E, Maciaszczyk-Dziubinska E, Branzei D, Wysocki R. Error-free DNA damage tolerance pathway is facilitated by the Irc5 translocase through cohesin. EMBO J 2018; 37:e98732. [PMID: 30111537 PMCID: PMC6138436 DOI: 10.15252/embj.201798732] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 07/20/2018] [Accepted: 07/25/2018] [Indexed: 12/20/2022] Open
Abstract
DNA damage tolerance (DDT) mechanisms facilitate replication resumption and completion when DNA replication is blocked by bulky DNA lesions. In budding yeast, template switching (TS) via the Rad18/Rad5 pathway is a favored DDT pathway that involves usage of the sister chromatid as a template to bypass DNA lesions in an error-free recombination-like process. Here, we establish that the Snf2 family translocase Irc5 is a novel factor that promotes TS and averts single-stranded DNA persistence during replication. We demonstrate that, during replication stress, Irc5 enables replication progression by assisting enrichment of cohesin complexes, recruited in an Scc2/Scc4-dependent fashion, near blocked replication forks. This allows efficient formation of sister chromatid junctions that are crucial for error-free DNA lesion bypass. Our results support the notion of a key role of cohesin in the completion of DNA synthesis under replication stress and reveal that the Rad18/Rad5-mediated DDT pathway is linked to cohesin enrichment at sites of perturbed replication via the Snf2 family translocase Irc5.
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Affiliation(s)
- Ireneusz Litwin
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Tomasz Bakowski
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Barnabas Szakal
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan, Italy
| | - Ewa Pilarczyk
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | | | - Dana Branzei
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Milan, Italy
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
| | - Robert Wysocki
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
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9
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Poli J, Gasser SM, Papamichos-Chronakis M. The INO80 remodeller in transcription, replication and repair. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0290. [PMID: 28847827 DOI: 10.1098/rstb.2016.0290] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2017] [Indexed: 02/06/2023] Open
Abstract
The accessibility of eukaryotic genomes to the action of enzymes involved in transcription, replication and repair is maintained despite the organization of DNA into nucleosomes. This access is often regulated by the action of ATP-dependent nucleosome remodellers. The INO80 class of nucleosome remodellers has unique structural features and it is implicated in a diverse array of functions, including transcriptional regulation, DNA replication and DNA repair. Underlying these diverse functions is the catalytic activity of the main ATPase subunit, which in the context of a multisubunit complex can shift nucleosomes and carry out histone dimer exchange. In vitro studies showed that INO80 promotes replication fork progression on a chromatin template, while in vivo it was shown to facilitate replication fork restart after stalling and to help evict RNA polymerase II at transcribed genes following the collision of a replication fork with transcription. More recent work in yeast implicates INO80 in the general eviction and degradation of nucleosomes following high doses of oxidative DNA damage. Beyond these replication and repair functions, INO80 was shown to repress inappropriate transcription at promoters in the opposite direction to the coding sequence. Here we discuss the ways in which INO80's diverse functions help maintain genome integrity.This article is part of the themed issue 'Chromatin modifiers and remodellers in DNA repair and signalling'.
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Affiliation(s)
- Jérôme Poli
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.,University of Montpellier and Centre de Recherche en Biologie Cellulaire (CRBM), UMR5237, CNRS, Montpellier 34095, Cedex 5, France
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland .,Faculty of Natural Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Manolis Papamichos-Chronakis
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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10
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Morrison AJ. Genome maintenance functions of the INO80 chromatin remodeller. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0289. [PMID: 28847826 DOI: 10.1098/rstb.2016.0289] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/06/2017] [Indexed: 12/15/2022] Open
Abstract
Chromatin modification is conserved in all eukaryotes and is required to facilitate and regulate DNA-templated processes. For example, chromatin manipulation, such as histone post-translational modification and nucleosome positioning, play critical roles in genome stability pathways. The INO80 chromatin-remodelling complex, which regulates the abundance and positioning of nucleosomes, is particularly important for proper execution of inducible responses to DNA damage. This review discusses the participation and activity of the INO80 complex in DNA repair and cell cycle checkpoint pathways, with emphasis on the Saccharomyces cerevisiae model system. Furthermore, the role of ATM/ATR kinases, central regulators of DNA damage signalling, in the regulation of INO80 function will be reviewed. In addition, emerging themes of chromatin remodelling in mitotic stability pathways and chromosome segregation will be introduced. These studies are critical to understanding the dynamic chromatin landscape that is rapidly and reversibly modified to maintain the integrity of the genome.This article is part of the themed issue 'Chromatin modifiers and remodellers in DNA repair and signalling'.
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Affiliation(s)
- Ashby J Morrison
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA 94305, USA
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11
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Chaudhury I, Koepp DM. Degradation of Mrc1 promotes recombination-mediated restart of stalled replication forks. Nucleic Acids Res 2017; 45:2558-2570. [PMID: 27956499 PMCID: PMC5389566 DOI: 10.1093/nar/gkw1249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 12/01/2016] [Indexed: 11/26/2022] Open
Abstract
The DNA replication or S-phase checkpoint monitors the integrity of DNA synthesis. Replication stress or DNA damage triggers fork stalling and checkpoint signaling to activate repair pathways. Recovery from checkpoint activation is critical for cell survival following DNA damage. Recovery from the S-phase checkpoint includes inactivation of checkpoint signaling and restart of stalled replication forks. Previous studies demonstrated that degradation of Mrc1, the Saccharomyces cerevisiae ortholog of human Claspin, is facilitated by the SCFDia2 ubiquitin ligase and is important for cell cycle re-entry after DNA damage-induced S-phase checkpoint activation. Here, we show that degradation of Mrc1 facilitated by the SCFDia2 complex is critical to restart stalled replication forks during checkpoint recovery. Using DNA fiber analysis, we showed that Dia2 functions with the Sgs1 and Mph1 helicases (orthologs of human BLM and FANCM, respectively) in the recombination-mediated fork restart pathway. In addition, Dia2 physically interacts with Sgs1 upon checkpoint activation. Importantly, failure to target Mrc1 for degradation during recovery inhibits Sgs1 chromatin association, but this can be alleviated by induced proteolysis of Mrc1 after checkpoint activation. Together, these studies provide new mechanistic insights into how cells recover from activation of the S-phase checkpoint.
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Affiliation(s)
- Indrajit Chaudhury
- Department of Genetics, Cell Biology and Development, 321 Church St. SE, University of Minnesota, Minneapolis, MN 55455 USA
| | - Deanna M Koepp
- Department of Genetics, Cell Biology and Development, 321 Church St. SE, University of Minnesota, Minneapolis, MN 55455 USA
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12
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Litwin I, Bakowski T, Maciaszczyk-Dziubinska E, Wysocki R. The LSH/HELLS homolog Irc5 contributes to cohesin association with chromatin in yeast. Nucleic Acids Res 2017; 45:6404-6416. [PMID: 28383696 PMCID: PMC5499779 DOI: 10.1093/nar/gkx240] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 03/28/2017] [Accepted: 04/03/2017] [Indexed: 11/29/2022] Open
Abstract
Accurate chromosome segregation is essential for every living cell as unequal distribution of chromosomes during cell division may result in genome instability that manifests in carcinogenesis and developmental disorders. Irc5 from Saccharomyces cerevisiae is a member of the conserved Snf2 family of ATP-dependent DNA translocases and its function is poorly understood. Here, we identify Irc5 as a novel interactor of the cohesin complex. Irc5 associates with Scc1 cohesin subunit and contributes to cohesin binding to chromatin. Disruption of IRC5 decreases cohesin levels at centromeres and chromosome arms, causing premature sister chromatid separation. Moreover, reduced cohesin occupancy at the rDNA region in cells lacking IRC5 leads to the loss of rDNA repeats. We also show that the translocase activity of Irc5 is required for its function in cohesion pathway. Finally, we demonstrate that in the absence of Irc5 both the level of chromatin-bound Scc2, a member of cohesin loading complex, and physical interaction between Scc1 and Scc2 are reduced. Our results suggest that Irc5 is an auxiliary factor that is involved in cohesin association with chromatin.
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Affiliation(s)
- Ireneusz Litwin
- Institute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Tomasz Bakowski
- Institute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland
| | | | - Robert Wysocki
- Institute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland
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13
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Siler J, Xia B, Wong C, Kath M, Bi X. Cell cycle-dependent positive and negative functions of Fun30 chromatin remodeler in DNA damage response. DNA Repair (Amst) 2017; 50:61-70. [PMID: 28089177 DOI: 10.1016/j.dnarep.2016.12.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/03/2016] [Accepted: 12/31/2016] [Indexed: 11/17/2022]
Abstract
The evolutionally conserved Fun30 chromatin remodeler in Saccharomyces cerevisiae has been shown to contribute to cellular resistance to genotoxic stress inflicted by camptothecin (CPT), methyl methanesulfonate (MMS) and hydroxyurea (HU). Fun30 aids in extensive DNA resection of DNA double stranded break (DSB) ends, which is thought to underlie its role in CPT-resistance. How Fun30 promotes MMS- or HU-resistance has not been resolved. Interestingly, we have recently found Fun30 to also play a negative role in cellular tolerance to MMS and HU in the absence of the Rad5-dependent DNA damage tolerance pathway. In this report, we show that Fun30 acts to down regulate Rad9-dependent DNA damage checkpoint triggered by CPT or MMS, but does not affect Rad9-independent intra-S phase replication checkpoint induced by MMS or HU. These results support the notion that Fun30 contributes to cellular response to DSBs by preventing excessive DNA damage checkpoint activation in addition to its role in facilitating DNA end resection. On the other hand, we present evidence suggesting that Fun30's negative function in MMS- and HU-tolerance in the absence of Rad5 is not related to its regulation of checkpoint activity. Moreover, we find Fun30 to be cell cycle regulated with its abundance peaking in G2/M phase of the cell cycle. Importantly, we demonstrate that artificially restricting Fun30 expression to G2/M does not affect its positive or negative function in genotoxin-resistance, but confining Fun30 to S phase abolishes its functions. These results indicate that both positive and negative functions of Fun30 in DNA damage response occur mainly in G2/M phase.
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Affiliation(s)
- Jasmine Siler
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Bowen Xia
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Carina Wong
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Morgan Kath
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Xin Bi
- Department of Biology, University of Rochester, Rochester, NY 14627, USA.
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14
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Kurat CF, Yeeles JTP, Patel H, Early A, Diffley JFX. Chromatin Controls DNA Replication Origin Selection, Lagging-Strand Synthesis, and Replication Fork Rates. Mol Cell 2017; 65:117-130. [PMID: 27989438 PMCID: PMC5222724 DOI: 10.1016/j.molcel.2016.11.016] [Citation(s) in RCA: 173] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/17/2016] [Accepted: 11/07/2016] [Indexed: 11/16/2022]
Abstract
The integrity of eukaryotic genomes requires rapid and regulated chromatin replication. How this is accomplished is still poorly understood. Using purified yeast replication proteins and fully chromatinized templates, we have reconstituted this process in vitro. We show that chromatin enforces DNA replication origin specificity by preventing non-specific MCM helicase loading. Helicase activation occurs efficiently in the context of chromatin, but subsequent replisome progression requires the histone chaperone FACT (facilitates chromatin transcription). The FACT-associated Nhp6 protein, the nucleosome remodelers INO80 or ISW1A, and the lysine acetyltransferases Gcn5 and Esa1 each contribute separately to maximum DNA synthesis rates. Chromatin promotes the regular priming of lagging-strand DNA synthesis by facilitating DNA polymerase α function at replication forks. Finally, nucleosomes disrupted during replication are efficiently re-assembled into regular arrays on nascent DNA. Our work defines the minimum requirements for chromatin replication in vitro and shows how multiple chromatin factors might modulate replication fork rates in vivo.
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Affiliation(s)
- Christoph F Kurat
- Clare Hall Laboratory, Francis Crick Institute, South Mimms, Hertfordshire EN6 3LD, UK
| | - Joseph T P Yeeles
- Clare Hall Laboratory, Francis Crick Institute, South Mimms, Hertfordshire EN6 3LD, UK
| | - Harshil Patel
- Lincoln's Inn Fields Laboratory, Francis Crick Institute, London NW1 1AT, UK
| | - Anne Early
- Clare Hall Laboratory, Francis Crick Institute, South Mimms, Hertfordshire EN6 3LD, UK
| | - John F X Diffley
- Clare Hall Laboratory, Francis Crick Institute, South Mimms, Hertfordshire EN6 3LD, UK.
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Recovery from the DNA Replication Checkpoint. Genes (Basel) 2016; 7:genes7110094. [PMID: 27801838 PMCID: PMC5126780 DOI: 10.3390/genes7110094] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/20/2016] [Accepted: 10/23/2016] [Indexed: 11/17/2022] Open
Abstract
Checkpoint recovery is integral to a successful checkpoint response. Checkpoint pathways monitor progress during cell division so that in the event of an error, the checkpoint is activated to block the cell cycle and activate repair pathways. Intrinsic to this process is that once repair has been achieved, the checkpoint signaling pathway is inactivated and cell cycle progression resumes. We use the term “checkpoint recovery” to describe the pathways responsible for the inactivation of checkpoint signaling and cell cycle re-entry after the initial stress has been alleviated. The DNA replication or S-phase checkpoint monitors the integrity of DNA synthesis. When replication stress is encountered, replication forks are stalled, and the checkpoint signaling pathway is activated. Central to recovery from the S-phase checkpoint is the restart of stalled replication forks. If checkpoint recovery fails, stalled forks may become unstable and lead to DNA breaks or unusual DNA structures that are difficult to resolve, causing genomic instability. Alternatively, if cell cycle resumption mechanisms become uncoupled from checkpoint inactivation, cells with under-replicated DNA might proceed through the cell cycle, also diminishing genomic stability. In this review, we discuss the molecular mechanisms that contribute to inactivation of the S-phase checkpoint signaling pathway and the restart of replication forks during recovery from replication stress.
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16
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Yadav T, Whitehouse I. Replication-Coupled Nucleosome Assembly and Positioning by ATP-Dependent Chromatin-Remodeling Enzymes. Cell Rep 2016; 15:715-723. [PMID: 27149855 DOI: 10.1016/j.celrep.2016.03.059] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/05/2016] [Accepted: 03/15/2016] [Indexed: 12/27/2022] Open
Abstract
During DNA replication, chromatin must be disassembled and faithfully reassembled on newly synthesized genomes. The mechanisms that govern the assembly of chromatin structures following DNA replication are poorly understood. Here, we exploited Okazaki fragment synthesis and other assays to study how nucleosomes are deposited and become organized in S. cerevisiae. We observe that global nucleosome positioning is quickly established on newly synthesized DNA in vivo. Importantly, we find that ATP-dependent chromatin-remodeling enzymes, Isw1 and Chd1, collaborate with histone chaperones to remodel nucleosomes as they are loaded behind a replication fork. Using a whole-genome sequencing approach, we determine that the positioning of newly deposited nucleosomes in vivo is specified by the combined actions of ATP-dependent chromatin-remodeling enzymes and select DNA-binding proteins. Altogether, our data provide in vivo evidence for coordinated "loading and remodeling" of nucleosomes behind the replication fork, allowing for rapid organization of chromatin during S phase.
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Affiliation(s)
- Tejas Yadav
- Weill Cornell Graduate School of Medical Sciences, 1300 York Avenue, New York, NY 10065, USA; Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Iestyn Whitehouse
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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