1
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Bainbridge LJ, Daigaku Y. Bulk synthesis and beyond: The roles of eukaryotic replicative DNA polymerases. DNA Repair (Amst) 2024; 141:103740. [PMID: 39096696 DOI: 10.1016/j.dnarep.2024.103740] [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: 05/14/2024] [Revised: 07/27/2024] [Accepted: 07/28/2024] [Indexed: 08/05/2024]
Abstract
An organism's genomic DNA must be accurately duplicated during each cell cycle. DNA synthesis is catalysed by DNA polymerase enzymes, which extend nucleotide polymers in a 5' to 3' direction. This inherent directionality necessitates that one strand is synthesised forwards (leading), while the other is synthesised backwards discontinuously (lagging) to couple synthesis to the unwinding of duplex DNA. Eukaryotic cells possess many diverse polymerases that coordinate to replicate DNA, with the three main replicative polymerases being Pol α, Pol δ and Pol ε. Studies conducted in yeasts and human cells utilising mutant polymerases that incorporate molecular signatures into nascent DNA implicate Pol ε in leading strand synthesis and Pol α and Pol δ in lagging strand replication. Recent structural insights have revealed how the spatial organization of these enzymes around the core helicase facilitates their strand-specific roles. However, various challenging situations during replication require flexibility in the usage of these enzymes, such as during replication initiation or encounters with replication-blocking adducts. This review summarises the roles of the replicative polymerases in bulk DNA replication and explores their flexible and dynamic deployment to complete genome replication. We also examine how polymerase usage patterns can inform our understanding of global replication dynamics by revealing replication fork directionality to identify regions of replication initiation and termination.
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Affiliation(s)
- Lewis J Bainbridge
- Cancer Genome Dynamics Project, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Yasukazu Daigaku
- Cancer Genome Dynamics Project, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan.
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2
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Triplett MK, Johnson MJ, Symington LS. Induction of homologous recombination by site-specific replication stress. DNA Repair (Amst) 2024; 142:103753. [PMID: 39190984 DOI: 10.1016/j.dnarep.2024.103753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 08/07/2024] [Accepted: 08/12/2024] [Indexed: 08/29/2024]
Abstract
DNA replication stress is one of the primary causes of genome instability. In response to replication stress, cells can employ replication restart mechanisms that rely on homologous recombination to resume replication fork progression and preserve genome integrity. In this review, we provide an overview of various methods that have been developed to induce site-specific replication fork stalling or collapse in eukaryotic cells. In particular, we highlight recent studies of mechanisms of replication-associated recombination resulting from site-specific protein-DNA barriers and single-strand breaks, and we discuss the contributions of these findings to our understanding of the consequences of these forms of stress on genome stability.
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Affiliation(s)
- Marina K Triplett
- Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Irving Medical Center, New York, NY 10032, United States; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, United States
| | - Matthew J Johnson
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, United States; Program in Biological Sciences, Columbia University, New York, NY 10027, United States
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, United States; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY 10032, United States.
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3
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Schirmeisen K, Naiman K, Fréon K, Besse L, Chakraborty S, Saada AA, Carr AM, Kramarz K, Lambert SAE. SUMO protease and proteasome recruitment at the nuclear periphery differently affect replication dynamics at arrested forks. Nucleic Acids Res 2024; 52:8286-8302. [PMID: 38917328 DOI: 10.1093/nar/gkae526] [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: 11/28/2023] [Revised: 05/02/2024] [Accepted: 06/10/2024] [Indexed: 06/27/2024] Open
Abstract
Nuclear pore complexes (NPCs) have emerged as genome organizers, defining a particular nuclear compartment enriched for SUMO protease and proteasome activities, and act as docking sites for the repair of DNA damage. In fission yeast, the anchorage of perturbed replication forks to NPCs is an integral part of the recombination-dependent replication restart mechanism (RDR) that resumes DNA synthesis at terminally dysfunctional forks. By mapping DNA polymerase usage, we report that SUMO protease Ulp1-associated NPCs ensure efficient initiation of restarted DNA synthesis, whereas proteasome-associated NPCs sustain the progression of restarted DNA polymerase. In contrast to Ulp1-dependent events, this last function is not alleviated by preventing SUMO chain formation. By analyzing the role of the nuclear basket, the nucleoplasmic extension of the NPC, we reveal that the activities of Ulp1 and the proteasome cannot compensate for each other and affect the dynamics of RDR in distinct ways. Our work probes two distinct mechanisms by which the NPC environment ensures optimal RDR, both controlled by different NPC components.
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Affiliation(s)
- Kamila Schirmeisen
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
| | - Karel Naiman
- INSERM U1068, CNRS UMR7258, Aix Marseille Univ U105, Institut Paoli-Calmettes, CRCM, Marseille, France
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Karine Fréon
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
| | - Laetitia Besse
- Institut Curie, Université PSL, CNRS UAR2016, Inserm US43, Université Paris-Saclay, Multimodal Imaging Center, 91400 Orsay, France
| | - Shrena Chakraborty
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
| | - Anissia Ait Saada
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Karol Kramarz
- Academic Excellence Hub - Research Centre for DNA Repair and Replication, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Sarah A E Lambert
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France
- Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France
- Equipe Labellisée Ligue Nationale Contre le cancer, France
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4
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Son MY, Belan O, Spirek M, Cibulka J, Nikulenkov F, Kim YY, Hwang S, Myung K, Montagna C, Kim TM, Krejci L, Hasty P. RAD51 separation of function mutation disables replication fork maintenance but preserves DSB repair. iScience 2024; 27:109524. [PMID: 38577109 PMCID: PMC10993188 DOI: 10.1016/j.isci.2024.109524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 03/01/2023] [Accepted: 03/14/2024] [Indexed: 04/06/2024] Open
Abstract
Homologous recombination (HR) protects replication forks (RFs) and repairs DNA double-strand breaks (DSBs). Within HR, BRCA2 regulates RAD51 via two interaction regions: the BRC repeats to form filaments on single-stranded DNA and exon 27 (Ex27) to stabilize the filament. Here, we identified a RAD51 S181P mutant that selectively disrupted the RAD51-Ex27 association while maintaining interaction with BRC repeat and proficiently forming filaments capable of DNA binding and strand invasion. Interestingly, RAD51 S181P was defective for RF protection/restart but proficient for DSB repair. Our data suggest that Ex27-mediated stabilization of RAD51 filaments is required for the protection of RFs, while it seems dispensable for the repair of DSBs.
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Affiliation(s)
- Mi Young Son
- Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA
| | - Ondrej Belan
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
| | - Mario Spirek
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00 Brno, Czech Republic
| | - Jakub Cibulka
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
| | - Fedor Nikulenkov
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
| | - You Young Kim
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Sunyoung Hwang
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Kyungjae Myung
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Cristina Montagna
- Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
| | - Tae Moon Kim
- Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA
- Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Lumir Krejci
- Department of Biology, Masaryk University, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Masaryk University, 625 00 Brno, Czech Republic
| | - Paul Hasty
- Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA
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5
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Martin R, Espinoza CY, Large CRL, Rosswork J, Van Bruinisse C, Miller AW, Sanchez JC, Miller M, Paskvan S, Alvino GM, Dunham MJ, Raghuraman MK, Brewer BJ. Template switching between the leading and lagging strands at replication forks generates inverted copy number variants through hairpin-capped extrachromosomal DNA. PLoS Genet 2024; 20:e1010850. [PMID: 38175823 PMCID: PMC10766183 DOI: 10.1371/journal.pgen.1010850] [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: 06/30/2023] [Accepted: 10/23/2023] [Indexed: 01/06/2024] Open
Abstract
Inherited and germ-line de novo copy number variants (CNVs) are increasingly found to be correlated with human developmental and cancerous phenotypes. Several models for template switching during replication have been proposed to explain the generation of these gross chromosomal rearrangements. We proposed a model of template switching (ODIRA-origin dependent inverted repeat amplification) in which simultaneous ligation of the leading and lagging strands at diverging replication forks could generate segmental inverted triplications through an extrachromosomal inverted circular intermediate. Here, we created a genetic assay using split-ura3 cassettes to trap the proposed inverted intermediate. However, instead of recovering circular inverted intermediates, we found inverted linear chromosomal fragments ending in native telomeres-suggesting that a template switch had occurred at the centromere-proximal fork of a replication bubble. As telomeric inverted hairpin fragments can also be created through double strand breaks we tested whether replication errors or repair of double stranded DNA breaks were the most likely initiating event. The results from CRISPR/Cas9 cleavage experiments and growth in the replication inhibitor hydroxyurea indicate that it is a replication error, not a double stranded break that creates the inverted junctions. Since inverted amplicons of the SUL1 gene occur during long-term growth in sulfate-limited chemostats, we sequenced evolved populations to look for evidence of linear intermediates formed by an error in replication. All of the data are compatible with a two-step version of the ODIRA model in which sequential template switching at short inverted repeats between the leading and lagging strands at a replication fork, followed by integration via homologous recombination, generates inverted interstitial triplications.
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Affiliation(s)
- Rebecca Martin
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Claudia Y. Espinoza
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Christopher R. L. Large
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Joshua Rosswork
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Cole Van Bruinisse
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Aaron W. Miller
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Joseph C. Sanchez
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Madison Miller
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Samantha Paskvan
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Gina M. Alvino
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Maitreya J. Dunham
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - M. K. Raghuraman
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Bonita J. Brewer
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
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6
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Jiang H, Chan YW. Chromatin bridges: stochastic breakage or regulated resolution? Trends Genet 2024; 40:69-82. [PMID: 37891096 DOI: 10.1016/j.tig.2023.10.004] [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: 08/15/2023] [Revised: 09/25/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023]
Abstract
Genetic material is organized in the form of chromosomes, which need to be segregated accurately into two daughter cells in each cell cycle. However, chromosome fusion or the presence of unresolved interchromosomal linkages lead to the formation of chromatin bridges, which can induce DNA lesions and genome instability. Persistent chromatin bridges are trapped in the cleavage furrow and are broken at or after abscission, the final step of cytokinesis. In this review, we focus on recent progress in understanding the mechanism of bridge breakage and resolution. We discuss the molecular machinery and enzymes that have been implicated in the breakage and processing of bridge DNA. In addition, we outline both the immediate outcomes and genomic consequences induced by bridge breakage.
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Affiliation(s)
- Huadong Jiang
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region of China
| | - Ying Wai Chan
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region of China.
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7
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Mason FM, Kounlavong ES, Tebeje AT, Dahiya R, Guess T, Khan A, Vlach L, Norris SR, Lovejoy CA, Dere R, Strahl BD, Ohi R, Ly P, Walker CL, Rathmell WK. SETD2 safeguards the genome against isochromosome formation. Proc Natl Acad Sci U S A 2023; 120:e2303752120. [PMID: 37722039 PMCID: PMC10523680 DOI: 10.1073/pnas.2303752120] [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: 03/06/2023] [Accepted: 08/11/2023] [Indexed: 09/20/2023] Open
Abstract
Isochromosomes are mirror-imaged chromosomes with simultaneous duplication and deletion of genetic material which may contain two centromeres to create isodicentric chromosomes. Although isochromosomes commonly occur in cancer and developmental disorders and promote genome instability, mechanisms that prevent isochromosomes are not well understood. We show here that the tumor suppressor and methyltransferase SETD2 is essential to prevent these errors. Using cellular and cytogenetic approaches, we demonstrate that loss of SETD2 or its epigenetic mark, histone H3 lysine 36 trimethylation (H3K36me3), results in the formation of isochromosomes as well as isodicentric and acentric chromosomes. These defects arise during DNA replication and are likely due to faulty homologous recombination by RAD52. These data provide a mechanism for isochromosome generation and demonstrate that SETD2 and H3K36me3 are essential to prevent the formation of this common mutable chromatin structure known to initiate a cascade of genomic instability in cancer.
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Affiliation(s)
- Frank M. Mason
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN37232
| | - Emily S. Kounlavong
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN37232
| | - Anteneh T. Tebeje
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN37232
| | - Rashmi Dahiya
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Tiffany Guess
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN37232
| | - Abid Khan
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC27599
| | - Logan Vlach
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN37232
| | - Stephen R. Norris
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN37232
| | | | - Ruhee Dere
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX77030
| | - Brian D. Strahl
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC27599
| | - Ryoma Ohi
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI48109
| | - Peter Ly
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Cheryl Lyn Walker
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX77030
| | - W. Kimryn Rathmell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN37232
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8
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Chakraborty S, Schirmeisen K, Lambert SA. The multifaceted functions of homologous recombination in dealing with replication-associated DNA damages. DNA Repair (Amst) 2023; 129:103548. [PMID: 37541027 DOI: 10.1016/j.dnarep.2023.103548] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/06/2023]
Abstract
The perturbation of DNA replication, a phenomena termed "replication stress", is a driving force of genome instability and a hallmark of cancer cells. Among the DNA repair mechanisms that contribute to tolerating replication stress, the homologous recombination pathway is central to the alteration of replication fork progression. In many organisms, defects in the homologous recombination machinery result in increased cell sensitivity to replication-blocking agents and a higher risk of cancer in humans. Moreover, the status of homologous recombination in cancer cells often correlates with the efficacy of anti-cancer treatment. In this review, we discuss our current understanding of the different functions of homologous recombination in fixing replication-associated DNA damage and contributing to complete genome duplication. We also examine which functions are pivotal in preventing cancer and genome instability.
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Affiliation(s)
- Shrena Chakraborty
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France; Equipe Labelisée Ligue Nationale Contre le Cancer, France
| | - Kamila Schirmeisen
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France; Equipe Labelisée Ligue Nationale Contre le Cancer, France
| | - Sarah Ae Lambert
- Institut Curie, Université PSL, CNRS UMR3348, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, 91400 Orsay, France; Equipe Labelisée Ligue Nationale Contre le Cancer, France.
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9
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Budden AM, Eravci M, Watson AT, Campillo-Funollet E, Oliver AW, Naiman K, Carr AM. Schizosaccharomyces pombe Rtf2 is important for replication fork barrier activity of RTS1 via splicing of Rtf1. eLife 2023; 12:e78554. [PMID: 37615341 PMCID: PMC10473836 DOI: 10.7554/elife.78554] [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: 03/11/2022] [Accepted: 08/19/2023] [Indexed: 08/25/2023] Open
Abstract
Arrested replication forks, when restarted by homologous recombination, result in error-prone DNA syntheses and non-allelic homologous recombination. Fission yeast RTS1 is a model fork barrier used to probe mechanisms of recombination-dependent restart. RTS1 barrier activity is entirely dependent on the DNA binding protein Rtf1 and partially dependent on a second protein, Rtf2. Human RTF2 was recently implicated in fork restart, leading us to examine fission yeast Rtf2's role in more detail. In agreement with previous studies, we observe reduced barrier activity upon rtf2 deletion. However, we identified Rtf2 to be physically associated with mRNA processing and splicing factors and rtf2 deletion to cause increased intron retention. One of the most affected introns resided in the rtf1 transcript. Using an intronless rtf1, we observed no reduction in RFB activity in the absence of Rtf2. Thus, Rtf2 is essential for correct rtf1 splicing to allow optimal RTS1 barrier activity.
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Affiliation(s)
- Alice M Budden
- Genome Damage and Stability Centre, University of SussexBrightonUnited Kingdom
| | - Murat Eravci
- Department of Biochemistry and Biomedicine, University of SussexBrightonUnited Kingdom
| | - Adam T Watson
- Genome Damage and Stability Centre, University of SussexBrightonUnited Kingdom
| | | | - Antony W Oliver
- Genome Damage and Stability Centre, University of SussexBrightonUnited Kingdom
| | - Karel Naiman
- Genome Damage and Stability Centre, University of SussexBrightonUnited Kingdom
| | - Antony M Carr
- Genome Damage and Stability Centre, University of SussexBrightonUnited Kingdom
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10
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RNA:DNA hybrids from Okazaki fragments contribute to establish the Ku-mediated barrier to replication-fork degradation. Mol Cell 2023; 83:1061-1074.e6. [PMID: 36868227 DOI: 10.1016/j.molcel.2023.02.008] [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: 12/14/2021] [Revised: 12/09/2022] [Accepted: 02/04/2023] [Indexed: 03/05/2023]
Abstract
Nonhomologous end-joining (NHEJ) factors act in replication-fork protection, restart, and repair. Here, we identified a mechanism related to RNA:DNA hybrids to establish the NHEJ factor Ku-mediated barrier to nascent strand degradation in fission yeast. RNase H activities promote nascent strand degradation and replication restart, with a prominent role of RNase H2 in processing RNA:DNA hybrids to overcome the Ku barrier to nascent strand degradation. RNase H2 cooperates with the MRN-Ctp1 axis to sustain cell resistance to replication stress in a Ku-dependent manner. Mechanistically, the need of RNaseH2 in nascent strand degradation requires the primase activity that allows establishing the Ku barrier to Exo1, whereas impairing Okazaki fragment maturation reinforces the Ku barrier. Finally, replication stress induces Ku foci in a primase-dependent manner and favors Ku binding to RNA:DNA hybrids. We propose a function for the RNA:DNA hybrid originating from Okazaki fragments in controlling the Ku barrier specifying nuclease requirement to engage fork resection.
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11
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Wang L, Zhang S, Fang J, Jin X, Mamut R, Li P. The Chloroplast Genome of the Lichen Photobiont Trebouxiophyceae sp. DW1 and Its Phylogenetic Implications. Genes (Basel) 2022; 13:genes13101840. [PMID: 36292725 PMCID: PMC9601494 DOI: 10.3390/genes13101840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/30/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022] Open
Abstract
Lichens are symbiotic associations of algae and fungi. The genetic mechanism of the symbiosis of lichens and the influence of symbiosis on the size and composition of the genomes of symbiotic algae have always been intriguing scientific questions explored by lichenologists. However, there were limited data on lichen genomes. Therefore, we isolated and purified a lichen symbiotic alga to obtain a single strain (Trebouxiophyceae sp. DW1), and then obtained its chloroplast genome information by next-generation sequencing (NGS). The chloroplast genome is 129,447 bp in length, and the GC content is 35.2%. Repetitive sequences with the length of 30–35 bp account for 1.27% of the total chloroplast genome. The simple sequence repeats are all mononucleotide repeats. Codon usage analysis showed that the genome tended to use codon ending in A/U. By comparing the length of different regions of Trebouxiophyceae genomes, we found that the changes in the length of exons, introns, and intergenic sequences affect the size of genomes. Trebouxiophyceae had an unstable chloroplast genome structure, with IRs repeatedly losing during evolution. Phylogenetic analysis showed that Trebouxiophyceae is paraphyletic, and Trebouxiophyceae sp. DW1 is sister to the clade of Koliella longiseta and Pabia signiensis.
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Affiliation(s)
- Lidan Wang
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830046, China
| | - Shenglu Zhang
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jinjin Fang
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830046, China
| | - Xinjie Jin
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Reyim Mamut
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830046, China
- Correspondence: (R.M.); (P.L.)
| | - Pan Li
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
- Correspondence: (R.M.); (P.L.)
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12
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Mohiuddin M, Kooy RF, Pearson CE. De novo mutations, genetic mosaicism and human disease. Front Genet 2022; 13:983668. [PMID: 36226191 PMCID: PMC9550265 DOI: 10.3389/fgene.2022.983668] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/08/2022] [Indexed: 11/23/2022] Open
Abstract
Mosaicism—the existence of genetically distinct populations of cells in a particular organism—is an important cause of genetic disease. Mosaicism can appear as de novo DNA mutations, epigenetic alterations of DNA, and chromosomal abnormalities. Neurodevelopmental or neuropsychiatric diseases, including autism—often arise by de novo mutations that usually not present in either of the parents. De novo mutations might occur as early as in the parental germline, during embryonic, fetal development, and/or post-natally, through ageing and life. Mutation timing could lead to mutation burden of less than heterozygosity to approaching homozygosity. Developmental timing of somatic mutation attainment will affect the mutation load and distribution throughout the body. In this review, we discuss the timing of de novo mutations, spanning from mutations in the germ lineage (all ages), to post-zygotic, embryonic, fetal, and post-natal events, through aging to death. These factors can determine the tissue specific distribution and load of de novo mutations, which can affect disease. The disease threshold burden of somatic de novo mutations of a particular gene in any tissue will be important to define.
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Affiliation(s)
- Mohiuddin Mohiuddin
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
- *Correspondence: Mohiuddin Mohiuddin, ; Christopher E. Pearson,
| | - R. Frank Kooy
- Department of Medical Genetics, University of Antwerp, Edegem, Belgium
| | - Christopher E. Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- *Correspondence: Mohiuddin Mohiuddin, ; Christopher E. Pearson,
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13
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Mellor C, Perez C, Sale JE. Creation and resolution of non-B-DNA structural impediments during replication. Crit Rev Biochem Mol Biol 2022; 57:412-442. [PMID: 36170051 PMCID: PMC7613824 DOI: 10.1080/10409238.2022.2121803] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 08/02/2022] [Accepted: 08/25/2022] [Indexed: 01/27/2023]
Abstract
During replication, folding of the DNA template into non-B-form secondary structures provides one of the most abundant impediments to the smooth progression of the replisome. The core replisome collaborates with multiple accessory factors to ensure timely and accurate duplication of the genome and epigenome. Here, we discuss the forces that drive non-B structure formation and the evidence that secondary structures are a significant and frequent source of replication stress that must be actively countered. Taking advantage of recent advances in the molecular and structural biology of the yeast and human replisomes, we examine how structures form and how they may be sensed and resolved during replication.
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Affiliation(s)
- Christopher Mellor
- Division of Protein & Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Consuelo Perez
- Division of Protein & Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Julian E Sale
- Division of Protein & Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
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14
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Peng J, Pei S, Cui Y, Xia Y, Huang Y, Wu X, Zheng M, Weng M, Han X, Fu H, Yang L, Zhou W, Fu Z, Wang S, Xie H. Comparative analysis of transient receptor potential channel 5 opposite strand-induced gene expression patterns and protein-protein interactions in triple-negative breast cancer. Oncol Lett 2022; 24:259. [PMID: 35765270 PMCID: PMC9219028 DOI: 10.3892/ol.2022.13379] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/04/2022] [Indexed: 11/06/2022] Open
Abstract
In patients with triple-negative breast cancer (TNBC), high tumour mutation burden and aberrant oncogene expression profiles are some of the causes of poor prognosis. Therefore, it is necessary to identify aberrantly expressed oncogenes, since they have the potential to serve as therapeutic targets. Transient receptor potential channel 5 opposite strand (TRPC5OS) has been previously shown to function as a novel tumour inducer. However, the underlying mechanism of TRPC5OS function in TNBC remain to be elucidated. Therefore, in the present study TRPC5OS expression was first measured in tissue samples of patients with TNBC and a panel of breast cancer cell lines (ZR-75-1, MDA-MB-453, SK-BR-3, JIMT-1, BT474 and HCC1937) by using qRT-PCR and Western blotting. Subsequently, the possible effects of TRPC5OS on MDA-MB-231 cells proliferation were determined using Cell Counting Kit-8 and 5-Ethynyl-2′-deoxyuridine assays after Lentiviral transfection of MDA-MB-231. In addition, potential interaction partners of TRPC5OS were explored using liquid chromatography-mass spectrometry (LC-MS)/MS. Gene expression patterns following TRPC5OS overexpression were also detected in MDA-MB-231 cells by using High-throughput sequencing. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) analysis were then used to systematically verify the potential interactions among the TRPC5OS-regulated genes. The potential relationship between TRPC5OS-interacting proteins and gene expression patterns were studied using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis. TRPC5OS expression was found to be significantly higher in TNBC tumour tissues and breast cancer cell lines compared with luminal tumour tissues and ZR-75-1. In addition, the overexpression of TRPC5OS significantly increased cell proliferation. High-throughput sequencing results revealed that 5,256 genes exhibited differential expression following TRPC5OS overexpression, including 3,269 upregulated genes and 1,987 downregulated genes. GO analysis results indicated that the functions of these differentially expressed genes were enriched in the categories of ‘cell division’ and ‘cell proliferation’ regulation. KEGG analysis showed that the TRPC5OS-regulated genes were associated with processes of ‘homologous recombination’ and ‘TNF signalling pathways’. Subsequently, 17 TRPC5OS-interacting proteins were found using LC-MS/MS and STRING analysis. The most important protein among interacting proteins was ENO1 which was associated with glycolysis and regulated proliferation of cancer. In summary, data from the present study suggest that TRPC5OS overexpression can increase TNBC cell proliferation and ENO1 may be a potential target protein mediated by TRPC5OS. Therefore, TRPC5OS may serve as a novel therapeutic target for TNBC.
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Affiliation(s)
- Jinghui Peng
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.,Breast Disease Laboratory, Women and Children Central Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Shengbin Pei
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.,Breast Disease Laboratory, Women and Children Central Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yangyang Cui
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yiqin Xia
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yue Huang
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Xiaowei Wu
- Breast Disease Laboratory, Women and Children Central Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Mingjie Zheng
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Miaomiao Weng
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Xu Han
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.,Breast Disease Laboratory, Women and Children Central Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Hongtao Fu
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.,Breast Disease Laboratory, Women and Children Central Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Lili Yang
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Wenbin Zhou
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Ziyi Fu
- Breast Disease Laboratory, Women and Children Central Laboratory, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Shui Wang
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Hui Xie
- Department of Breast Surgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
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15
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Functions of Breast Cancer Predisposition Genes: Implications for Clinical Management. Int J Mol Sci 2022; 23:ijms23137481. [PMID: 35806485 PMCID: PMC9267387 DOI: 10.3390/ijms23137481] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 02/04/2023] Open
Abstract
Approximately 5–10% of all breast cancer (BC) cases are caused by germline pathogenic variants (GPVs) in various cancer predisposition genes (CPGs). The most common contributors to hereditary BC are BRCA1 and BRCA2, which are associated with hereditary breast and ovarian cancer (HBOC). ATM, BARD1, CHEK2, PALB2, RAD51C, and RAD51D have also been recognized as CPGs with a high to moderate risk of BC. Primary and secondary cancer prevention strategies have been established for HBOC patients; however, optimal preventive strategies for most hereditary BCs have not yet been established. Most BC-associated CPGs participate in DNA damage repair pathways and cell cycle checkpoint mechanisms, and function jointly in such cascades; therefore, a fundamental understanding of the disease drivers in such cascades can facilitate the accurate estimation of the genetic risk of developing BC and the selection of appropriate preventive and therapeutic strategies to manage hereditary BCs. Herein, we review the functions of key BC-associated CPGs and strategies for the clinical management in individuals harboring the GPVs of such genes.
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16
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Porubsky D, Höps W, Ashraf H, Hsieh P, Rodriguez-Martin B, Yilmaz F, Ebler J, Hallast P, Maria Maggiolini FA, Harvey WT, Henning B, Audano PA, Gordon DS, Ebert P, Hasenfeld P, Benito E, Zhu Q, Lee C, Antonacci F, Steinrücken M, Beck CR, Sanders AD, Marschall T, Eichler EE, Korbel JO. Recurrent inversion polymorphisms in humans associate with genetic instability and genomic disorders. Cell 2022; 185:1986-2005.e26. [PMID: 35525246 PMCID: PMC9563103 DOI: 10.1016/j.cell.2022.04.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/14/2022] [Accepted: 04/08/2022] [Indexed: 12/13/2022]
Abstract
Unlike copy number variants (CNVs), inversions remain an underexplored genetic variation class. By integrating multiple genomic technologies, we discover 729 inversions in 41 human genomes. Approximately 85% of inversions <2 kbp form by twin-priming during L1 retrotransposition; 80% of the larger inversions are balanced and affect twice as many nucleotides as CNVs. Balanced inversions show an excess of common variants, and 72% are flanked by segmental duplications (SDs) or retrotransposons. Since flanking repeats promote non-allelic homologous recombination, we developed complementary approaches to identify recurrent inversion formation. We describe 40 recurrent inversions encompassing 0.6% of the genome, showing inversion rates up to 2.7 × 10-4 per locus per generation. Recurrent inversions exhibit a sex-chromosomal bias and co-localize with genomic disorder critical regions. We propose that inversion recurrence results in an elevated number of heterozygous carriers and structural SD diversity, which increases mutability in the population and predisposes specific haplotypes to disease-causing CNVs.
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Affiliation(s)
- David Porubsky
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA
| | - Wolfram Höps
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Hufsah Ashraf
- Heinrich Heine University, Medical Faculty, Institute for Medical Biometry and Bioinformatics, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - PingHsun Hsieh
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA
| | - Bernardo Rodriguez-Martin
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Feyza Yilmaz
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | - Jana Ebler
- Heinrich Heine University, Medical Faculty, Institute for Medical Biometry and Bioinformatics, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Pille Hallast
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | - Flavia Angela Maria Maggiolini
- Department of Biology, University of Bari "Aldo Moro", 70125 Bari, Italy; Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria-Centro di Ricerca Viticoltura ed Enologia (CREA-VE), Via Casamassima 148, 70010 Turi, Italy
| | - William T Harvey
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA
| | - Barbara Henning
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA
| | - Peter A Audano
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | - David S Gordon
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Peter Ebert
- Heinrich Heine University, Medical Faculty, Institute for Medical Biometry and Bioinformatics, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Patrick Hasenfeld
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Eva Benito
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Qihui Zhu
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | - Charles Lee
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | | | - Matthias Steinrücken
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA; Department of Human Genetics, University of Chicago, Chicago, IL, USA
| | - Christine R Beck
- The Jackson Laboratory for Genomic Medicine, 10 Discovery Drive, Farmington, CT 06032, USA; The University of Connecticut Health Center, 400 Farmington Rd., Farmington, CT 06032, USA
| | - Ashley D Sanders
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany; Charité-Universitätsmedizin, Berlin, Berlin, Germany
| | - Tobias Marschall
- Heinrich Heine University, Medical Faculty, Institute for Medical Biometry and Bioinformatics, Moorenstraße 5, 40225 Düsseldorf, Germany.
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA; Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
| | - Jan O Korbel
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstr. 1, 69117 Heidelberg, Germany; European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, UK.
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17
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Mak CH. Nucleic acid folding simulations using a physics-based atomistic free energy model. J Chem Phys 2022; 156:174114. [PMID: 35525642 DOI: 10.1063/5.0086304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Performing full-resolution atomistic simulations of nucleic acid folding has remained a challenge for biomolecular modeling. Understanding how nucleic acids fold and how they transition between different folded structures as they unfold and refold has important implications for biology. This paper reports a theoretical model and computer simulation of the ab initio folding of DNA inverted repeat sequences. The formulation is based on an all-atom conformational model of the sugar-phosphate backbone via chain closure, and it incorporates three major molecular-level driving forces-base stacking, counterion-induced backbone self-interactions, and base pairing-via separate analytical theories designed to capture and reproduce the effects of the solvent without requiring explicit water and ions in the simulation. To accelerate computational throughput, a mixed numerical/analytical algorithm for the calculation of the backbone conformational volume is incorporated into the Monte Carlo simulation, and special stochastic sampling techniques were employed to achieve the computational efficiency needed to fold nucleic acids from scratch. This paper describes implementation details, benchmark results, and the advantages and technical challenges with this approach.
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Affiliation(s)
- Chi H Mak
- Departments of Chemistry and Quantitative and Computational Biology, and Center of Applied Mathematical Sciences, University of Southern California, Los Angeles, California 90089, USA
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18
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Joseph CR, Dusi S, Giannattasio M, Branzei D. Rad51-mediated replication of damaged templates relies on monoSUMOylated DDK kinase. Nat Commun 2022; 13:2480. [PMID: 35513396 PMCID: PMC9072374 DOI: 10.1038/s41467-022-30215-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 04/21/2022] [Indexed: 12/24/2022] Open
Abstract
DNA damage tolerance (DDT), activated by replication stress during genome replication, is mediated by translesion synthesis and homologous recombination (HR). Here we uncover that DDK kinase, essential for replication initiation, is critical for replication-associated recombination-mediated DDT. DDK relies on its multi-monoSUMOylation to facilitate HR-mediated DDT and optimal retention of Rad51 recombinase at replication damage sites. Impairment of DDK kinase activity, reduced monoSUMOylation and mutations in the putative SUMO Interacting Motifs (SIMs) of Rad51 impair replication-associated recombination and cause fork uncoupling with accumulation of large single-stranded DNA regions at fork branching points. Notably, genetic activation of salvage recombination rescues the uncoupled fork phenotype but not the recombination-dependent gap-filling defect of DDK mutants, revealing that the salvage recombination pathway operates preferentially proximal to fork junctions at stalled replication forks. Overall, we uncover that monoSUMOylated DDK acts with Rad51 in an axis that prevents replication fork uncoupling and mediates recombination-dependent gap-filling.
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Affiliation(s)
- Chinnu Rose Joseph
- IFOM, Istituto Fondazione di Oncologia Molecolare, Via Adamello 16, 20139, Milan, Italy
| | - Sabrina Dusi
- IFOM, Istituto Fondazione di Oncologia Molecolare, Via Adamello 16, 20139, Milan, Italy
| | - Michele Giannattasio
- IFOM, Istituto Fondazione di Oncologia Molecolare, Via Adamello 16, 20139, Milan, Italy
- Università degli Studi di Milano, Dipartimento di Oncologia ed Emato-Oncologia, Via S. Sofia 9/1, 20122, Milano, Italy
| | - Dana Branzei
- IFOM, Istituto Fondazione di Oncologia Molecolare, Via Adamello 16, 20139, Milan, Italy.
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), 27100, Pavia, Italy.
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19
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Whale AJ, King M, Hull RM, Krueger F, Houseley J. Stimulation of adaptive gene amplification by origin firing under replication fork constraint. Nucleic Acids Res 2022; 50:915-936. [PMID: 35018465 PMCID: PMC8789084 DOI: 10.1093/nar/gkab1257] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 02/06/2023] Open
Abstract
Adaptive mutations can cause drug resistance in cancers and pathogens, and increase the tolerance of agricultural pests and diseases to chemical treatment. When and how adaptive mutations form is often hard to discern, but we have shown that adaptive copy number amplification of the copper resistance gene CUP1 occurs in response to environmental copper due to CUP1 transcriptional activation. Here we dissect the mechanism by which CUP1 transcription in budding yeast stimulates copy number variation (CNV). We show that transcriptionally stimulated CNV requires TREX-2 and Mediator, such that cells lacking TREX-2 or Mediator respond normally to copper but cannot acquire increased resistance. Mediator and TREX-2 can cause replication stress by tethering transcribed loci to nuclear pores, a process known as gene gating, and transcription at the CUP1 locus causes a TREX-2-dependent accumulation of replication forks indicative of replication fork stalling. TREX-2-dependent CUP1 gene amplification occurs by a Rad52 and Rad51-mediated homologous recombination mechanism that is enhanced by histone H3K56 acetylation and repressed by Pol32 and Pif1. CUP1 amplification is also critically dependent on late-firing replication origins present in the CUP1 repeats, and mutations that remove or inactivate these origins strongly suppress the acquisition of copper resistance. We propose that replicative stress imposed by nuclear pore association causes replication bubbles from these origins to collapse soon after activation, leaving a tract of H3K56-acetylated chromatin that promotes secondary recombination events during elongation after replication fork re-start events. The capacity for inefficient replication origins to promote copy number variation renders certain genomic regions more fragile than others, and therefore more likely to undergo adaptive evolution through de novo gene amplification.
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Affiliation(s)
- Alex J Whale
- Epigenetics Programme, Babraham Institute, Cambridge, UK
| | - Michelle King
- Epigenetics Programme, Babraham Institute, Cambridge, UK
| | - Ryan M Hull
- Epigenetics Programme, Babraham Institute, Cambridge, UK
| | - Felix Krueger
- Babraham Bioinformatics, Babraham Institute, Cambridge, UK
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20
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Protein innovation through template switching in the Saccharomyces cerevisiae lineage. Sci Rep 2021; 11:22558. [PMID: 34799587 PMCID: PMC8604942 DOI: 10.1038/s41598-021-01736-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 10/27/2021] [Indexed: 11/08/2022] Open
Abstract
DNA polymerase template switching between short, non-identical inverted repeats (IRs) is a genetic mechanism that leads to the homogenization of IR arms and to IR spacer inversion, which cause multinucleotide mutations (MNMs). It is unknown if and how template switching affects gene evolution. In this study, we performed a phylogenetic analysis to determine the effect of template switching between IR arms on coding DNA of Saccharomyces cerevisiae. To achieve this, perfect IRs that co-occurred with MNMs between a strain and its parental node were identified in S. cerevisiae strains. We determined that template switching introduced MNMs into 39 protein-coding genes through S. cerevisiae evolution, resulting in both arm homogenization and inversion of the IR spacer. These events in turn resulted in nonsynonymous substitutions and up to five neighboring amino acid replacements in a single gene. The study demonstrates that template switching is a powerful generator of multiple substitutions within codons. Additionally, some template switching events occurred more than once during S. cerevisiae evolution. Our findings suggest that template switching constitutes a general mutagenic mechanism that results in both nonsynonymous substitutions and parallel evolution, which are traditionally considered as evidence for positive selection, without the need for adaptive explanations.
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21
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Sebastian R, Aladjem MI, Oberdoerffer P. Encounters in Three Dimensions: How Nuclear Topology Shapes Genome Integrity. Front Genet 2021; 12:746380. [PMID: 34745220 PMCID: PMC8566435 DOI: 10.3389/fgene.2021.746380] [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: 07/23/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
Almost 25 years ago, the phosphorylation of a chromatin component, histone H2AX, was discovered as an integral part of the DNA damage response in eukaryotes. Much has been learned since then about the control of DNA repair in the context of chromatin. Recent technical and computational advances in imaging, biophysics and deep sequencing have led to unprecedented insight into nuclear organization, highlighting the impact of three-dimensional (3D) chromatin structure and nuclear topology on DNA repair. In this review, we will describe how DNA repair processes have adjusted to and in many cases adopted these organizational features to ensure accurate lesion repair. We focus on new findings that highlight the importance of chromatin context, topologically associated domains, phase separation and DNA break mobility for the establishment of repair-conducive nuclear environments. Finally, we address the consequences of aberrant 3D genome maintenance for genome instability and disease.
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Affiliation(s)
- Robin Sebastian
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, United States
| | - Mirit I Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, United States
| | - Philipp Oberdoerffer
- Division of Cancer Biology, National Cancer Institute, NIH, Rockville, MD, United States
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22
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Gold MA, Whalen JM, Freon K, Hong Z, Iraqui I, Lambert SAE, Freudenreich CH. Restarted replication forks are error-prone and cause CAG repeat expansions and contractions. PLoS Genet 2021; 17:e1009863. [PMID: 34673780 PMCID: PMC8562783 DOI: 10.1371/journal.pgen.1009863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 11/02/2021] [Accepted: 10/06/2021] [Indexed: 12/16/2022] Open
Abstract
Disease-associated trinucleotide repeats form secondary DNA structures that interfere with replication and repair. Replication has been implicated as a mechanism that can cause repeat expansions and contractions. However, because structure-forming repeats are also replication barriers, it has been unclear whether the instability occurs due to slippage during normal replication progression through the repeat, slippage or misalignment at a replication stall caused by the repeat, or during subsequent replication of the repeat by a restarted fork that has altered properties. In this study, we have specifically addressed the fidelity of a restarted fork as it replicates through a CAG/CTG repeat tract and its effect on repeat instability. To do this, we used a well-characterized site-specific replication fork barrier (RFB) system in fission yeast that creates an inducible and highly efficient stall that is known to restart by recombination-dependent replication (RDR), in combination with long CAG repeat tracts inserted at various distances and orientations with respect to the RFB. We find that replication by the restarted fork exhibits low fidelity through repeat sequences placed 2-7 kb from the RFB, exhibiting elevated levels of Rad52- and Rad8ScRad5/HsHLTF-dependent instability. CAG expansions and contractions are not elevated to the same degree when the tract is just in front or behind the barrier, suggesting that the long-traveling Polδ-Polδ restarted fork, rather than fork reversal or initial D-loop synthesis through the repeat during stalling and restart, is the greatest source of repeat instability. The switch in replication direction that occurs due to replication from a converging fork while the stalled fork is held at the barrier is also a significant contributor to the repeat instability profile. Our results shed light on a long-standing question of how fork stalling and RDR contribute to expansions and contractions of structure-forming trinucleotide repeats, and reveal that tolerance to replication stress by fork restart comes at the cost of increased instability of repetitive sequences.
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Affiliation(s)
- Michaela A. Gold
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Jenna M. Whalen
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Karine Freon
- Institut Curie, Université PSL, Orsay, France
- Université Paris-Saclay, Orsay, France
| | - Zixin Hong
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Ismail Iraqui
- Institut Curie, Université PSL, Orsay, France
- Université Paris-Saclay, Orsay, France
| | - Sarah A. E. Lambert
- Institut Curie, Université PSL, Orsay, France
- Université Paris-Saclay, Orsay, France
- Equipes Labélisées Ligue Nationale Contre Le Cancer, Orsay, France
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23
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Carr A, Lambert S. Recombination-dependent replication: new perspectives from site-specific fork barriers. Curr Opin Genet Dev 2021; 71:129-135. [PMID: 34364031 DOI: 10.1016/j.gde.2021.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/16/2021] [Accepted: 07/18/2021] [Indexed: 02/07/2023]
Abstract
Replication stress (RS) is intrinsic to normal cell growth, is enhanced by exogenous factors and elevated in many cancer cells due to oncogene expression. Most genetic changes are a result of RS and the mechanisms by which cells tolerate RS has received considerable attention because of the link to cancer evolution and opportunities for cancer cell-specific therapeutic intervention. Site-specific replication fork barriers have provided unique insights into how cells respond to RS and their recent use has allowed a deeper understanding of the mechanistic and spatial mechanism that restart arrested forks and how these correlate with RS-dependent mutagenesis. Here we review recent data from site-specific fork arrest systems used in yeast and highlight their strengths and limitations.
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Affiliation(s)
- Antony Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Sussex, BN1 9RQ, UK
| | - Sarah Lambert
- Institut Curie, Université PSL, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Equipe Labélisée Ligue Nationale Contre Le Cancer, 91400 Orsay, France.
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Su J, Xu R, Mongia P, Toyofuku N, Nakagawa T. Fission yeast Rad8/HLTF facilitates Rad52-dependent chromosomal rearrangements through PCNA lysine 107 ubiquitination. PLoS Genet 2021; 17:e1009671. [PMID: 34292936 PMCID: PMC8297803 DOI: 10.1371/journal.pgen.1009671] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/18/2021] [Indexed: 11/19/2022] Open
Abstract
Gross chromosomal rearrangements (GCRs), including translocation, deletion, and inversion, can cause cell death and genetic diseases such as cancer in multicellular organisms. Rad51, a DNA strand exchange protein, suppresses GCRs by repairing spontaneous DNA damage through a conservative way of homologous recombination, gene conversion. On the other hand, Rad52 that catalyzes single-strand annealing (SSA) causes GCRs using homologous sequences. However, the detailed mechanism of Rad52-dependent GCRs remains unclear. Here, we provide genetic evidence that fission yeast Rad8/HLTF facilitates Rad52-dependent GCRs through the ubiquitination of lysine 107 (K107) of PCNA, a DNA sliding clamp. In rad51Δ cells, loss of Rad8 eliminated 75% of the isochromosomes resulting from centromere inverted repeat recombination, showing that Rad8 is essential for the formation of the majority of isochromosomes in rad51Δ cells. Rad8 HIRAN and RING finger mutations reduced GCRs, suggesting that Rad8 facilitates GCRs through 3’ DNA-end binding and ubiquitin ligase activity. Mms2 and Ubc4 but not Ubc13 ubiquitin-conjugating enzymes were required for GCRs. Consistent with this, mutating PCNA K107 rather than the well-studied PCNA K164 reduced GCRs. Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs, as PCNA K107R, rad8, and rad52 mutations epistatically reduced GCRs. In contrast to GCRs, PCNA K107R did not significantly change gene conversion rates, suggesting a specific role of PCNA K107 ubiquitination in GCRs. PCNA K107R enhanced temperature-sensitive growth defects of DNA ligase I cdc17-K42 mutant, implying that PCNA K107 ubiquitination occurs when Okazaki fragment maturation fails. Remarkably, K107 is located at the interface between PCNA subunits, and an interface mutation D150E bypassed the requirement of PCNA K107 and Rad8 ubiquitin ligase for GCRs. These data suggest that Rad8-dependent PCNA K107 ubiquitination facilitates Rad52-dependent GCRs by changing the PCNA clamp structure. Gross chromosomal rearrangements (GCRs), including translocation, can alter gene dosage and activity, resulting in genetic diseases such as cancer. However, GCRs can occur by some enzymes, including Rad52 recombinase, and result in chromosomal evolution. Therefore, GCRs are not only pathological but also physiological phenomena from an evolutionary point of view. However, the detailed mechanism of GCRs remains unclear. Here, using fission yeast, we show that the homolog of human HLTF, Rad8 causes GCRs through noncanonical ubiquitination of proliferating cellular nuclear antigen (PCNA) at a lysine 107 (K107). Rad51, a DNA strand exchange protein, suppresses the formation of isochromosomes whose arms mirror each another and chromosomal truncation. We found that, like Rad52, Rad8 is required for isochromosome formation but not chromosomal truncation in rad51Δ cells, showing a specific role of Rad8 in homology-mediated GCRs. Mutations in Rad8 ubiquitin E3 ligase RING finger domain, Mms2-Ubc4 ubiquitin-conjugating enzymes, and PCNA K107 reduced GCRs in rad51Δ cells, suggesting that Rad8-Mms2-Ubc4-dependent PCNA K107 ubiquitination facilitates GCRs. PCNA trimers form a DNA sliding clamp. The K107 residue is located at the PCNA-PCNA interface, and an interface mutation D150E restored GCRs in PCNA K107R mutant cells. This study provides genetic evidence that Rad8-dependent PCNA K107 ubiquitination facilitates GCRs by changing the PCNA clamp structure.
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Affiliation(s)
- Jie Su
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Ran Xu
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Piyusha Mongia
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Naoko Toyofuku
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Takuro Nakagawa
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan
- * E-mail:
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Al-Zain AM, Symington LS. The dark side of homology-directed repair. DNA Repair (Amst) 2021; 106:103181. [PMID: 34311272 DOI: 10.1016/j.dnarep.2021.103181] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 10/20/2022]
Abstract
DNA double strand breaks (DSB) are cytotoxic lesions that can lead to genome rearrangements and genomic instability, which are hallmarks of cancer. The two main DSB repair pathways are non-homologous end joining and homologous recombination (HR). While HR is generally highly accurate, it has the potential for rearrangements that occur directly or through intermediates generated during the repair process. Whole genome sequencing of cancers has revealed numerous types of structural rearrangement signatures that are often indicative of repair mediated by sequence homology. However, it can be challenging to delineate repair mechanisms from sequence analysis of rearrangement end products from cancer genomes, or even model systems, because the same rearrangements can be generated by different pathways. Here, we review homology-directed repair pathways and their consequences. Exploring those pathways can lead to a greater understanding of rearrangements that occur in cancer cells.
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Affiliation(s)
- Amr M Al-Zain
- Program in Biological Sciences, Columbia University, New York, NY, 10027, United States; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, 10032, United States.
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Liu Y, Wang L, Xu X, Yuan Y, Zhang B, Li Z, Xie Y, Yan R, Zheng Z, Ji J, Murray JM, Carr AM, Kong D. The intra-S phase checkpoint directly regulates replication elongation to preserve the integrity of stalled replisomes. Proc Natl Acad Sci U S A 2021; 118:e2019183118. [PMID: 34108240 PMCID: PMC8214678 DOI: 10.1073/pnas.2019183118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
DNA replication is dramatically slowed down under replication stress. The regulation of replication speed is a conserved response in eukaryotes and, in fission yeast, requires the checkpoint kinases Rad3ATR and Cds1Chk2 However, the underlying mechanism of this checkpoint regulation remains unresolved. Here, we report that the Rad3ATR-Cds1Chk2 checkpoint directly targets the Cdc45-MCM-GINS (CMG) replicative helicase under replication stress. When replication forks stall, the Cds1Chk2 kinase directly phosphorylates Cdc45 on the S275, S322, and S397 residues, which significantly reduces CMG helicase activity. Furthermore, in cds1Chk2 -mutated cells, the CMG helicase and DNA polymerases are physically separated, potentially disrupting replisomes and collapsing replication forks. This study demonstrates that the intra-S phase checkpoint directly regulates replication elongation, reduces CMG helicase processivity, prevents CMG helicase delinking from DNA polymerases, and therefore helps preserve the integrity of stalled replisomes and replication forks.
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Affiliation(s)
- Yang Liu
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Lu Wang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Xin Xu
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Yue Yuan
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Bo Zhang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Zeyang Li
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Yuchen Xie
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Rui Yan
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Zeqi Zheng
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Jianguo Ji
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
| | - Johanne M Murray
- Genome Damage and Stability Center, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, United Kingdom
| | - Antony M Carr
- Genome Damage and Stability Center, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, United Kingdom
| | - Daochun Kong
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China;
- National Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China
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Wu L, Jin L, Chen W, Liu JM, Hu J, Yu Q, Ren XL, Huang B, He H. The true incidence of chromosomal mosaicism after preimplantation genetic testing is much lower than that indicated by trophectoderm biopsy. Hum Reprod 2021; 36:1691-1701. [PMID: 33860322 DOI: 10.1093/humrep/deab064] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/08/2021] [Indexed: 12/16/2022] Open
Abstract
STUDY QUESTION What is the true incidence of chromosomal mosaicism in embryos analyzed by preimplantation genetic testing (PGT). SUMMARY ANSWER The true incidence of chromosomal mosaicism is much lower than we usually surmise. WHAT IS KNOWN ALREADY In recent years, contemporary methods for chromosome analysis, along with the biopsy of more than one cell, have given rise to an increased rate of chromosomal mosaicism detection after preimplantation genetic testing for aneuploidy. However, the exorbitant incidence of mosaicism represents a dilemma and imposes restrictions on the application of PGT treatment. Concern has been raised about the possibility that the incidence of chromosomal mosaicism is overestimated and quite a few of the results are false-positive errors. However, studies verifying the diagnosis of chromosomal mosaicism and assessing the true incidence of chromosomal mosaicism are limited. STUDY DESIGN, SIZE, DURATION A total of 1719 blastocysts from 380 patients who underwent PGT treatment were retrospectively analyzed to evaluate the typical incidence of mosaicism. Then 101 embryos donated by 70 couples were re-biopsied and dissected into three portions if available: trophectoderm (TE), inner cell mass (ICM), and the remaining portions. All the portions were tested using next-generation sequencing (NGS), and the results were compared to the original diagnosis. PARTICIPANTS/MATERIALS, SETTING, METHODS The setting for this study was a university-affiliated center with an in-house PGT laboratory. All samples were amplified with multiple annealing and looping-based amplification cycles (MALBACs) and the NGS was carried out on a Life Technologies Ion Proton platform. MAIN RESULTS AND THE ROLE OF CHANCE A clinical TE biopsy revealed an incidence of 11.9% for diploid-aneuploid mosaicism (DAM), 17.3% for aneuploid mosaicism (AM) and 29.1% in total. After rebiopsy, 94.1% whole-chromosome aneuploidies and 82.8% segmental-chromosome aneuploidies were confirmed in the embryos. As for the mosaic errors, only 32 (31.7%) out of 101 embryos presented with uniform chromosomal aberrations in agreement with the original biopsy results, 15 (14.8%) embryos presented with de novo chromosomal aberrations, and 54 (53.5%) embryos showed a euploid profile in all portions. Among the 32 uniform embryos, the true mosaicism was confirmed in only 4 cases, where a reciprocal chromosomal aberration was identified; 14 embryos presented with identical mosaicism, providing the moderate evidence for true mosaicism; and 14 embryos displayed uniform full aneuploidies in all portions of embryo, revealing a high-grade mosaicism or a false-negative diagnosis. Logistical regression analysis revealed that the concordance rate with ICM was associated with the type and level of mosaicism. The concordance rate of segmental-chromosome mosaicism was significantly lower than whole-chromosome mosaicism (adjusted Odds Ratio (aOR): 5.137 (1.061, 24.876), P = 0.042) and compared to DAM, the concordance rate of AM was significantly higher (aOR: 6.546 (1.354, 31.655), P = 0.019). The concordance rate also increased with increasing levels of mosaicism (P < 0.001). LIMITATIONS, REASONS FOR CAUTION This study was limited by a small sample size and the use of a single whole-genome amplification (WGA) method and NGS platform. These findings are only applicable to samples subjected to MALBAC amplification and Ion Proton platform, and studies involving larger sample sizes and multiple WGA methods and NGS platforms are required to prove our findings. WIDER IMPLICATIONS OF THE FINDINGS TE biopsy is reliable to detect whole-chromosome aneuploidies, but the ability to diagnose mosaicism is doubtful. More attention should be paid to false-positive and false-negative errors in NGS-based PGT, especially for laboratories using less stringent criteria for mosaicism classification (i.e. 20-80%), which might be subject to a much higher false-positive mosaicism rate in the practice. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by grants from the National Key R&D Program of China (No. 2016YFC1000206-5) and the National Natural Science Foundation of China (No. 81701509). TRIAL REGISTRATION NUMBER N/A.
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Affiliation(s)
- L Wu
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - L Jin
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - W Chen
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - J M Liu
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - J Hu
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Q Yu
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - X L Ren
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - B Huang
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - H He
- Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
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28
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Tye S, Ronson GE, Morris JR. A fork in the road: Where homologous recombination and stalled replication fork protection part ways. Semin Cell Dev Biol 2021; 113:14-26. [PMID: 32653304 PMCID: PMC8082280 DOI: 10.1016/j.semcdb.2020.07.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/06/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022]
Abstract
In response to replication hindrances, DNA replication forks frequently stall and are remodelled into a four-way junction. In such a structure the annealed nascent strand is thought to resemble a DNA double-strand break and remodelled forks are vulnerable to nuclease attack by MRE11 and DNA2. Proteins that promote the recruitment, loading and stabilisation of RAD51 onto single-stranded DNA for homology search and strand exchange in homologous recombination (HR) repair and inter-strand cross-link repair also act to set up RAD51-mediated protection of nascent DNA at stalled replication forks. However, despite the similarities of these pathways, several lines of evidence indicate that fork protection is not simply analogous to the RAD51 loading step of HR. Protection of stalled forks not only requires separate functions of a number of recombination proteins, but also utilises nucleases important for the resection steps of HR in alternative ways. Here we discuss how fork protection arises and how its differences with HR give insights into the differing contexts of these two pathways.
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Affiliation(s)
- Stephanie Tye
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, SW7 2AZ, UK
| | - George E Ronson
- University of Birmingham, College of Medical Dental Schools, Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK
| | - Joanna R Morris
- University of Birmingham, College of Medical Dental Schools, Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK.
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29
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Etheridge TJ, Villahermosa D, Campillo-Funollet E, Herbert AD, Irmisch A, Watson AT, Dang HQ, Osborne MA, Oliver AW, Carr AM, Murray JM. Live-cell single-molecule tracking highlights requirements for stable Smc5/6 chromatin association in vivo. eLife 2021; 10:e68579. [PMID: 33860765 PMCID: PMC8075580 DOI: 10.7554/elife.68579] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 04/15/2021] [Indexed: 12/17/2022] Open
Abstract
The essential Smc5/6 complex is required in response to replication stress and is best known for ensuring the fidelity of homologous recombination. Using single-molecule tracking in live fission yeast to investigate Smc5/6 chromatin association, we show that Smc5/6 is chromatin associated in unchallenged cells and this depends on the non-SMC protein Nse6. We define a minimum of two Nse6-dependent sub-pathways, one of which requires the BRCT-domain protein Brc1. Using defined mutants in genes encoding the core Smc5/6 complex subunits, we show that the Nse3 double-stranded DNA binding activity and the arginine fingers of the two Smc5/6 ATPase binding sites are critical for chromatin association. Interestingly, disrupting the single-stranded DNA (ssDNA) binding activity at the hinge region does not prevent chromatin association but leads to elevated levels of gross chromosomal rearrangements during replication restart. This is consistent with a downstream function for ssDNA binding in regulating homologous recombination.
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Affiliation(s)
- Thomas J Etheridge
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Desiree Villahermosa
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Eduard Campillo-Funollet
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Alex David Herbert
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Anja Irmisch
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Adam T Watson
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Hung Q Dang
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Mark A Osborne
- Chemistry Department, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Antony W Oliver
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
| | - Johanne M Murray
- Genome Damage and Stability Centre, School of Life Sciences, University of SussexFalmerUnited Kingdom
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30
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DNA2 in Chromosome Stability and Cell Survival-Is It All about Replication Forks? Int J Mol Sci 2021; 22:ijms22083984. [PMID: 33924313 PMCID: PMC8069077 DOI: 10.3390/ijms22083984] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 01/16/2023] Open
Abstract
The conserved nuclease-helicase DNA2 has been linked to mitochondrial myopathy, Seckel syndrome, and cancer. Across species, the protein is indispensable for cell proliferation. On the molecular level, DNA2 has been implicated in DNA double-strand break (DSB) repair, checkpoint activation, Okazaki fragment processing (OFP), and telomere homeostasis. More recently, a critical contribution of DNA2 to the replication stress response and recovery of stalled DNA replication forks (RFs) has emerged. Here, we review the available functional and phenotypic data and propose that the major cellular defects associated with DNA2 dysfunction, and the links that exist with human disease, can be rationalized through the fundamental importance of DNA2-dependent RF recovery to genome duplication. Being a crucial player at stalled RFs, DNA2 is a promising target for anti-cancer therapy aimed at eliminating cancer cells by replication-stress overload.
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31
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Misova I, Pitelova A, Budis J, Gazdarica J, Sedlackova T, Jordakova A, Benko Z, Smondrkova M, Mayerova N, Pichlerova K, Strieskova L, Prevorovsky M, Gregan J, Cipak L, Szemes T, Polakova SB. Repression of a large number of genes requires interplay between homologous recombination and HIRA. Nucleic Acids Res 2021; 49:1914-1934. [PMID: 33511417 PMCID: PMC7913671 DOI: 10.1093/nar/gkab027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 01/06/2021] [Accepted: 01/09/2021] [Indexed: 12/13/2022] Open
Abstract
During homologous recombination, Dbl2 protein is required for localisation of Fbh1, an F-box helicase that efficiently dismantles Rad51-DNA filaments. RNA-seq analysis of dbl2Δ transcriptome showed that the dbl2 deletion results in upregulation of more than 500 loci in Schizosaccharomyces pombe. Compared with the loci with no change in expression, the misregulated loci in dbl2Δ are closer to long terminal and long tandem repeats. Furthermore, the misregulated loci overlap with antisense transcripts, retrotransposons, meiotic genes and genes located in subtelomeric regions. A comparison of the expression profiles revealed that Dbl2 represses the same type of genes as the HIRA histone chaperone complex. Although dbl2 deletion does not alleviate centromeric or telomeric silencing, it suppresses the silencing defect at the outer centromere caused by deletion of hip1 and slm9 genes encoding subunits of the HIRA complex. Moreover, our analyses revealed that cells lacking dbl2 show a slight increase of nucleosomes at transcription start sites and increased levels of methylated histone H3 (H3K9me2) at centromeres, subtelomeres, rDNA regions and long terminal repeats. Finally, we show that other proteins involved in homologous recombination, such as Fbh1, Rad51, Mus81 and Rad54, participate in the same gene repression pathway.
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Affiliation(s)
- Ivana Misova
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia
| | - Alexandra Pitelova
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia
| | - Jaroslav Budis
- Comenius University Science Park, 841 04 Bratislava, Slovakia
- Geneton Ltd., 841 04 Bratislava, Slovakia
- Slovak Centre of Scientific and Technical Information, 811 04 Bratislava, Slovakia
| | - Juraj Gazdarica
- Geneton Ltd., 841 04 Bratislava, Slovakia
- Slovak Centre of Scientific and Technical Information, 811 04 Bratislava, Slovakia
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University in Bratislava, 841 04 Bratislava, Slovakia
| | - Tatiana Sedlackova
- Comenius University Science Park, 841 04 Bratislava, Slovakia
- Geneton Ltd., 841 04 Bratislava, Slovakia
| | - Anna Jordakova
- Department of Cell Biology, Faculty of Science, Charles University, 128 00 Praha 2, Czechia
| | - Zsigmond Benko
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia
- Department of Molecular Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, H-4010 Debrecen, Hungary
| | - Maria Smondrkova
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, 841 04 Bratislava, Slovakia
| | - Nina Mayerova
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, 841 04 Bratislava, Slovakia
| | - Karoline Pichlerova
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia
| | - Lucia Strieskova
- Comenius University Science Park, 841 04 Bratislava, Slovakia
- Geneton Ltd., 841 04 Bratislava, Slovakia
| | - Martin Prevorovsky
- Department of Cell Biology, Faculty of Science, Charles University, 128 00 Praha 2, Czechia
| | - Juraj Gregan
- Advanced Microscopy Facility, VBCF and Department of Chromosome Biology, Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Lubos Cipak
- Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, 845 05 Bratislava, Slovakia
| | - Tomas Szemes
- Comenius University Science Park, 841 04 Bratislava, Slovakia
- Geneton Ltd., 841 04 Bratislava, Slovakia
- Slovak Centre of Scientific and Technical Information, 811 04 Bratislava, Slovakia
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University in Bratislava, 841 04 Bratislava, Slovakia
| | - Silvia Bagelova Polakova
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, 840 05 Bratislava, Slovakia
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, 841 04 Bratislava, Slovakia
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32
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Naiman K, Campillo-Funollet E, Watson AT, Budden A, Miyabe I, Carr AM. Replication dynamics of recombination-dependent replication forks. Nat Commun 2021; 12:923. [PMID: 33568651 PMCID: PMC7876095 DOI: 10.1038/s41467-021-21198-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/16/2021] [Indexed: 12/30/2022] Open
Abstract
Replication forks restarted by homologous recombination are error prone and replicate both strands semi-conservatively using Pol δ. Here, we use polymerase usage sequencing to visualize in vivo replication dynamics of HR-restarted forks at an S. pombe replication barrier, RTS1, and model replication by Monte Carlo simulation. We show that HR-restarted forks synthesise both strands with Pol δ for up to 30 kb without maturing to a δ/ε configuration and that Pol α is not used significantly on either strand, suggesting the lagging strand template remains as a gap that is filled in by Pol δ later. We further demonstrate that HR-restarted forks progress uninterrupted through a fork barrier that arrests canonical forks. Finally, by manipulating lagging strand resection during HR-restart by deleting pku70, we show that the leading strand initiates replication at the same position, signifying the stability of the 3' single strand in the context of increased resection.
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Affiliation(s)
- Karel Naiman
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK.
| | | | - Adam T Watson
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Alice Budden
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Izumi Miyabe
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, UK.
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33
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Suzuki R, Murata MM, Manguso N, Watanabe T, Mouakkad-Montoya L, Igari F, Rahman MM, Qu Y, Cui X, Giuliano AE, Takeda S, Tanaka H. The fragility of a structurally diverse duplication block triggers recurrent genomic amplification. Nucleic Acids Res 2021; 49:244-256. [PMID: 33290559 PMCID: PMC7797068 DOI: 10.1093/nar/gkaa1136] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/20/2020] [Accepted: 12/05/2020] [Indexed: 11/12/2022] Open
Abstract
The human genome contains hundreds of large, structurally diverse blocks that are insufficiently represented in the reference genome and are thus not amenable to genomic analyses. Structural diversity in the human population suggests that these blocks are unstable in the germline; however, whether or not these blocks are also unstable in the cancer genome remains elusive. Here we report that the 500 kb block called KRTAP_region_1 (KRTAP-1) on 17q12-21 recurrently demarcates the amplicon of the ERBB2 (HER2) oncogene in breast tumors. KRTAP-1 carries numerous tandemly-duplicated segments that exhibit diversity within the human population. We evaluated the fragility of the block by cytogenetically measuring the distances between the flanking regions and found that spontaneous distance outliers (i.e DNA breaks) appear more frequently at KRTAP-1 than at the representative common fragile site (CFS) FRA16D. Unlike CFSs, KRTAP-1 is not sensitive to aphidicolin. The exonuclease activity of DNA repair protein Mre11 protects KRTAP-1 from breaks, whereas CtIP does not. Breaks at KRTAP-1 lead to the palindromic duplication of the ERBB2 locus and trigger Breakage-Fusion-Bridge cycles. Our results indicate that an insufficiently investigated area of the human genome is fragile and could play a crucial role in cancer genome evolution.
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Affiliation(s)
- Ryusuke Suzuki
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Michael M Murata
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Nicholas Manguso
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Takaaki Watanabe
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | | | - Fumie Igari
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Md Maminur Rahman
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Ying Qu
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Xiaojiang Cui
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.,Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Armando E Giuliano
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.,Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.,Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Hisashi Tanaka
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.,Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.,Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
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34
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The nuclear pore primes recombination-dependent DNA synthesis at arrested forks by promoting SUMO removal. Nat Commun 2020; 11:5643. [PMID: 33159083 PMCID: PMC7648084 DOI: 10.1038/s41467-020-19516-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 10/16/2020] [Indexed: 12/31/2022] Open
Abstract
Nuclear Pore complexes (NPCs) act as docking sites to anchor particular DNA lesions facilitating DNA repair by elusive mechanisms. Using replication fork barriers in fission yeast, we report that relocation of arrested forks to NPCs occurred after Rad51 loading and its enzymatic activity. The E3 SUMO ligase Pli1 acts at arrested forks to safeguard integrity of nascent strands and generates poly-SUMOylation which promote relocation to NPCs but impede the resumption of DNA synthesis by homologous recombination (HR). Anchorage to NPCs allows SUMO removal by the SENP SUMO protease Ulp1 and the proteasome, promoting timely resumption of DNA synthesis. Preventing Pli1-mediated SUMO chains was sufficient to bypass the need for anchorage to NPCs and the inhibitory effect of poly-SUMOylation on HR-mediated DNA synthesis. Our work establishes a novel spatial control of Recombination-Dependent Replication (RDR) at a unique sequence that is distinct from mechanisms engaged at collapsed-forks and breaks within repeated sequences. In yeast, collapsed forks shift to the nuclear periphery to associate with two distinct perinuclear anchorage sites such as the nuclear pore complex. Here, the authors reveal the mechanisms engaged at nuclear pore complex facilitating fork integrity and restart via SUMO regulation.
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35
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Falquet B, Ölmezer G, Enkner F, Klein D, Challa K, Appanah R, Gasser SM, Rass U. Disease-associated DNA2 nuclease-helicase protects cells from lethal chromosome under-replication. Nucleic Acids Res 2020; 48:7265-7278. [PMID: 32544229 PMCID: PMC7367196 DOI: 10.1093/nar/gkaa524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 05/21/2020] [Accepted: 06/09/2020] [Indexed: 01/28/2023] Open
Abstract
DNA2 is an essential nuclease–helicase implicated in DNA repair, lagging-strand DNA synthesis, and the recovery of stalled DNA replication forks (RFs). In Saccharomyces cerevisiae, dna2Δ inviability is reversed by deletion of the conserved helicase PIF1 and/or DNA damage checkpoint-mediator RAD9. It has been suggested that Pif1 drives the formation of long 5′-flaps during Okazaki fragment maturation, and that the essential function of Dna2 is to remove these intermediates. In the absence of Dna2, 5′-flaps are thought to accumulate on the lagging strand, resulting in DNA damage-checkpoint arrest and cell death. In line with Dna2’s role in RF recovery, we find that the loss of Dna2 results in severe chromosome under-replication downstream of endogenous and exogenous RF-stalling. Importantly, unfaithful chromosome replication in Dna2-mutant cells is exacerbated by Pif1, which triggers the DNA damage checkpoint along a pathway involving Pif1’s ability to promote homologous recombination-coupled replication. We propose that Dna2 fulfils its essential function by promoting RF recovery, facilitating replication completion while suppressing excessive RF restart by recombination-dependent replication (RDR) and checkpoint activation. The critical nature of Dna2’s role in controlling the fate of stalled RFs provides a framework to rationalize the involvement of DNA2 in Seckel syndrome and cancer.
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Affiliation(s)
- Benoît Falquet
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Gizem Ölmezer
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Franz Enkner
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Dominique Klein
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Rowin Appanah
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, CH-4056 Basel, Switzerland
| | - Ulrich Rass
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland.,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
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36
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Appanah R, Jones D, Falquet B, Rass U. Limiting homologous recombination at stalled replication forks is essential for cell viability: DNA2 to the rescue. Curr Genet 2020; 66:1085-1092. [PMID: 32909097 PMCID: PMC7599155 DOI: 10.1007/s00294-020-01106-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 08/27/2020] [Accepted: 09/01/2020] [Indexed: 12/18/2022]
Abstract
The disease-associated nuclease–helicase DNA2 has been implicated in DNA end-resection during DNA double-strand break repair, Okazaki fragment processing, and the recovery of stalled DNA replication forks (RFs). Its role in Okazaki fragment processing has been proposed to explain why DNA2 is indispensable for cell survival across organisms. Unexpectedly, we found that DNA2 has an essential role in suppressing homologous recombination (HR)-dependent replication restart at stalled RFs. In the absence of DNA2-mediated RF recovery, excessive HR-restart of stalled RFs results in toxic levels of abortive recombination intermediates that lead to DNA damage-checkpoint activation and terminal cell-cycle arrest. While HR proteins protect and restart stalled RFs to promote faithful genome replication, these findings show how HR-dependent replication restart is actively constrained by DNA2 to ensure cell survival. These new insights disambiguate the effects of DNA2 dysfunction on cell survival, and provide a framework to rationalize the association of DNA2 with cancer and the primordial dwarfism disorder Seckel syndrome based on its role in RF recovery.
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Affiliation(s)
- Rowin Appanah
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - David Jones
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - Benoît Falquet
- Friedrich Miescher Institute for Biomedical Research, 4058, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, 4056, Basel, Switzerland
| | - Ulrich Rass
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ, UK.
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37
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Guilliam TA, Yeeles JTP. An updated perspective on the polymerase division of labor during eukaryotic DNA replication. Crit Rev Biochem Mol Biol 2020; 55:469-481. [PMID: 32883112 DOI: 10.1080/10409238.2020.1811630] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In eukaryotes three DNA polymerases (Pols), α, δ, and ε, are tasked with bulk DNA synthesis of nascent strands during genome duplication. Most evidence supports a model where Pol α initiates DNA synthesis before Pol ε and Pol δ replicate the leading and lagging strands, respectively. However, a number of recent reports, enabled by advances in biochemical and genetic techniques, have highlighted emerging roles for Pol δ in all stages of leading-strand synthesis; initiation, elongation, and termination, as well as fork restart. By focusing on these studies, this review provides an updated perspective on the division of labor between the replicative polymerases during DNA replication.
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Affiliation(s)
- Thomas A Guilliam
- Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Joseph T P Yeeles
- Division of Protein and Nucleic Acid Chemistry, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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38
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Todd RT, Selmecki A. Expandable and reversible copy number amplification drives rapid adaptation to antifungal drugs. eLife 2020; 9:e58349. [PMID: 32687060 PMCID: PMC7371428 DOI: 10.7554/elife.58349] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
Previously, we identified long repeat sequences that are frequently associated with genome rearrangements, including copy number variation (CNV), in many diverse isolates of the human fungal pathogen Candida albicans (Todd et al., 2019). Here, we describe the rapid acquisition of novel, high copy number CNVs during adaptation to azole antifungal drugs. Single-cell karyotype analysis indicates that these CNVs appear to arise via a dicentric chromosome intermediate and breakage-fusion-bridge cycles that are repaired using multiple distinct long inverted repeat sequences. Subsequent removal of the antifungal drug can lead to a dramatic loss of the CNV and reversion to the progenitor genotype and drug susceptibility phenotype. These findings support a novel mechanism for the rapid acquisition of antifungal drug resistance and provide genomic evidence for the heterogeneity frequently observed in clinical settings.
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Affiliation(s)
- Robert T Todd
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
| | - Anna Selmecki
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
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39
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Tanaka H, Watanabe T. Mechanisms Underlying Recurrent Genomic Amplification in Human Cancers. Trends Cancer 2020; 6:462-477. [PMID: 32383436 PMCID: PMC7285850 DOI: 10.1016/j.trecan.2020.02.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 12/17/2022]
Abstract
Focal copy-number increases (genomic amplification) pinpoint oncogenic driver genes and therapeutic targets in cancer genomes. With the advent of genomic technologies, recurrent genomic amplification has been mapped throughout the genome. Recurrent amplification could be solely due to positive selection for the tumor-promoting effects of amplified gene products. Alternatively, recurrence could result from the susceptibility of the loci to amplification. Distinguishing between these possibilities requires a full understanding of the amplification mechanisms. Two mechanisms, the formation of double minute (DM) chromosomes and breakage-fusion-bridge (BFB) cycles, have been repeatedly linked to genomic amplification, and the impact of both mechanisms has been confirmed in cancer genomics data. We review the details of these mechanisms and discuss the mechanisms underlying recurrence.
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Affiliation(s)
- Hisashi Tanaka
- Department of Surgery, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA; Biomedical Sciences, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA; Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA.
| | - Takaaki Watanabe
- Department of Surgery, Cedars-Sinai Medical Center, West Hollywood, CA 90046, USA; Molecular Life Science, Tokai University School of Medicine, Kanagawa, Japan
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40
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Girardi L, Serdarogullari M, Patassini C, Poli M, Fabiani M, Caroselli S, Coban O, Findikli N, Boynukalin FK, Bahceci M, Chopra R, Canipari R, Cimadomo D, Rienzi L, Ubaldi F, Hoffmann E, Rubio C, Simon C, Capalbo A. Incidence, Origin, and Predictive Model for the Detection and Clinical Management of Segmental Aneuploidies in Human Embryos. Am J Hum Genet 2020; 106:525-534. [PMID: 32220293 DOI: 10.1016/j.ajhg.2020.03.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 03/06/2020] [Indexed: 12/12/2022] Open
Abstract
Despite next-generation sequencing, which now allows for the accurate detection of segmental aneuploidies from in vitro fertilization embryo biopsies, the origin and characteristics of these aneuploidies are still relatively unknown. Using a multifocal biopsy approach (four trophectoderms [TEs] and one inner cell mass [ICM] analyzed per blastocyst; n = 390), we determine the origin of the aneuploidy and the diagnostic predictive value of segmental aneuploidy detection in TE biopsies toward the ICM's chromosomal constitution. Contrary to the prevalent meiotic origin of whole-chromosome aneuploidies, we show that sub-chromosomal abnormalities in human blastocysts arise from mitotic errors in around 70% of cases. As a consequence, the positive-predictive value toward ICM configuration was significantly lower for segmental as compared to whole-chromosome aneuploidies (70.8% versus 97.18%, respectively). In order to enhance the clinical utility of reporting segmental findings in clinical TE biopsies, we have developed and clinically verified a risk stratification model based on a second TE biopsy confirmation and segmental length; this model can significantly improve the prediction of aneuploidy risk in the ICM in over 86% of clinical cases enrolled. In conclusion, we provide evidence of the predominant mitotic origin of segmental aneuploidies in preimplantation embryos and develop a risk stratification model that can help post-test genetic counseling and that facilitates the decision-making process on clinical utilization of these embryos.
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41
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Zhang R, Ge F, Li H, Chen Y, Zhao Y, Gao Y, Liu Z, Yang L. PCIR: a database of Plant Chloroplast Inverted Repeats. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2020; 2019:5611292. [PMID: 31696928 PMCID: PMC6835207 DOI: 10.1093/database/baz127] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/26/2019] [Accepted: 10/07/2019] [Indexed: 01/06/2023]
Abstract
Inverted repeats (IRs) serve as potential biomarkers for genomic instability, DNA replication and other genetic processes. However, little information can be found in databases to help researchers recognize potential IR nucleotides, explore junction sites and annotate related functional genes. Plant Chloroplast Inverted Repeats (PCIR) is an interactive, web-based platform containing various sequenced chloroplast genomes that enables detection, searching and visualization of large-scale detailed information on IRs. PCIR contains many datasets, including 21 433 IRs, 113 plants chloroplast genomes, 16 948 functional genes and 21 659 visual maps. This database offers an online prediction tool for detecting IRs based on DNA sequences. PCIR can also analyze phylogenetic relationships using IR information among different species and provide users with high-quality marker maps. This database will be a valuable resource for IR distribution patterns, related genes and architectural features.
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Affiliation(s)
- Rui Zhang
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Fangfang Ge
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Huayang Li
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Yudong Chen
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Ying Zhao
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Ying Gao
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Zhiguo Liu
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
| | - Long Yang
- Agricultural Big-Data Research Center and College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China
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42
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Barg-Wojas A, Muraszko J, Kramarz K, Schirmeisen K, Baranowska G, Carr AM, Dziadkowiec D. Schizosaccharomyces pombe DNA translocases Rrp1 and Rrp2 have distinct roles at centromeres and telomeres that ensure genome stability. J Cell Sci 2020; 133:jcs230193. [PMID: 31932509 DOI: 10.1242/jcs.230193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 12/23/2019] [Indexed: 12/13/2022] Open
Abstract
The regulation of telomere and centromere structure and function is essential for maintaining genome integrity. Schizosaccharomyces pombe Rrp1 and Rrp2 are orthologues of Saccharomyces cerevisiae Uls1, a SWI2/SNF2 DNA translocase and SUMO-targeted ubiquitin ligase. Here, we show that Rrp1 or Rrp2 overproduction leads to chromosome instability and growth defects, a reduction in global histone levels and mislocalisation of centromere-specific histone Cnp1. These phenotypes depend on putative DNA translocase activities of Rrp1 and Rrp2, suggesting that Rrp1 and Rrp2 may be involved in modulating nucleosome dynamics. Furthermore, we confirm that Rrp2, but not Rrp1, acts at telomeres, reflecting a previously described interaction between Rrp2 and Top2. In conclusion, we identify roles for Rrp1 and Rrp2 in maintaining centromere function by modulating histone dynamics, contributing to the preservation of genome stability during vegetative cell growth.
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Affiliation(s)
- Anna Barg-Wojas
- Faculty of Biotechnology, University of Wrocław, 50-383 Wrocław, Poland
| | - Jakub Muraszko
- Faculty of Biotechnology, University of Wrocław, 50-383 Wrocław, Poland
| | - Karol Kramarz
- Institut Curie, Centre National de la Recherche Scientifique, F-91405, Orsay, France
| | | | | | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
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43
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Schizosaccharomyces pombe Assays to Study Mitotic Recombination Outcomes. Genes (Basel) 2020; 11:genes11010079. [PMID: 31936815 PMCID: PMC7016768 DOI: 10.3390/genes11010079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/07/2020] [Accepted: 01/07/2020] [Indexed: 01/16/2023] Open
Abstract
The fission yeast—Schizosaccharomyces pombe—has emerged as a powerful tractable system for studying DNA damage repair. Over the last few decades, several powerful in vivo genetic assays have been developed to study outcomes of mitotic recombination, the major repair mechanism of DNA double strand breaks and stalled or collapsed DNA replication forks. These assays have significantly increased our understanding of the molecular mechanisms underlying the DNA damage response pathways. Here, we review the assays that have been developed in fission yeast to study mitotic recombination.
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44
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Zapatka M, Pociño-Merino I, Heluani-Gahete H, Bermúdez-López M, Tarrés M, Ibars E, Solé-Soler R, Gutiérrez-Escribano P, Apostolova S, Casas C, Aragon L, Wellinger R, Colomina N, Torres-Rosell J. Sumoylation of Smc5 Promotes Error-free Bypass at Damaged Replication Forks. Cell Rep 2019; 29:3160-3172.e4. [DOI: 10.1016/j.celrep.2019.10.123] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 09/25/2019] [Accepted: 10/29/2019] [Indexed: 12/15/2022] Open
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45
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Hardy J, Dai D, Ait Saada A, Teixeira-Silva A, Dupoiron L, Mojallali F, Fréon K, Ochsenbein F, Hartmann B, Lambert S. Histone deposition promotes recombination-dependent replication at arrested forks. PLoS Genet 2019; 15:e1008441. [PMID: 31584934 PMCID: PMC6795475 DOI: 10.1371/journal.pgen.1008441] [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: 05/20/2019] [Revised: 10/16/2019] [Accepted: 09/20/2019] [Indexed: 11/18/2022] Open
Abstract
Replication stress poses a serious threat to genome stability. Recombination-Dependent-Replication (RDR) promotes DNA synthesis resumption from arrested forks. Despite the identification of chromatin restoration pathways after DNA repair, crosstalk coupling RDR and chromatin assembly is largely unexplored. The fission yeast Chromatin Assembly Factor-1, CAF-1, is known to promote RDR. Here, we addressed the contribution of histone deposition to RDR. We expressed a mutated histone, H3-H113D, to genetically alter replication-dependent chromatin assembly by destabilizing (H3-H4)2 tetramer. We established that DNA synthesis-dependent histone deposition, by CAF-1 and Asf1, promotes RDR by preventing Rqh1-mediated disassembly of joint-molecules. The recombination factor Rad52 promotes CAF-1 binding to sites of recombination-dependent DNA synthesis, indicating that histone deposition occurs downstream Rad52. Histone deposition and Rqh1 activity act synergistically to promote cell resistance to camptothecin, a topoisomerase I inhibitor that induces replication stress. Moreover, histone deposition favors non conservative recombination events occurring spontaneously in the absence of Rqh1, indicating that the stabilization of joint-molecules by histone deposition also occurs independently of Rqh1 activity. These results indicate that histone deposition plays an active role in promoting RDR, a benefit counterbalanced by stabilizing at-risk joint-molecules for genome stability.
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Affiliation(s)
- Julien Hardy
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Dingli Dai
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Anissia Ait Saada
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Ana Teixeira-Silva
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Louise Dupoiron
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Fatemeh Mojallali
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Karine Fréon
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
| | - Francoise Ochsenbein
- CEA, DRF, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, Gif-sur-Yvette, France
| | - Brigitte Hartmann
- Laboratoire de Biologie et Pharmacologie Appliquée (LBPA) UMR 8113, CNRS / ENS de Cachan, Cachan cedex, France
| | - Sarah Lambert
- Institut Curie, PSL Research University, UMR3348, Orsay, France.,University Paris Sud, Paris-Saclay University, UMR3348, Orsay, France.,CNRS, UMR3348, Orsay France
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46
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Ait-Saada A, Khorosjutina O, Chen J, Kramarz K, Maksimov V, Svensson JP, Lambert S, Ekwall K. Chromatin remodeler Fft3 plays a dual role at blocked DNA replication forks. Life Sci Alliance 2019; 2:e201900433. [PMID: 31575705 PMCID: PMC6771652 DOI: 10.26508/lsa.201900433] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 09/23/2019] [Accepted: 09/24/2019] [Indexed: 01/26/2023] Open
Abstract
Here, we investigate the function of fission yeast Fun30/Smarcad1 family of SNF2 ATPase-dependent chromatin remodeling enzymes in DNA damage repair. There are three Fun30 homologues in fission yeast, Fft1, Fft2, and Fft3. We find that only Fft3 has a function in DNA repair and it is needed for single-strand annealing of an induced double-strand break. Furthermore, we use an inducible replication fork barrier system to show that Fft3 has two distinct roles at blocked DNA replication forks. First, Fft3 is needed for the resection of nascent strands, and second, it is required to restart the blocked forks. The latter function is independent of its ATPase activity.
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Affiliation(s)
- Anissia Ait-Saada
- Institut Curie, Paris-Saclay University, Centre National de la Recherche Scientifique, Unités Mixtes de Recherche 3348, F-91405, Orsay, France
| | - Olga Khorosjutina
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Jiang Chen
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Karol Kramarz
- Institut Curie, Paris-Saclay University, Centre National de la Recherche Scientifique, Unités Mixtes de Recherche 3348, F-91405, Orsay, France
| | - Vladimir Maksimov
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - J Peter Svensson
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Sarah Lambert
- Institut Curie, Paris-Saclay University, Centre National de la Recherche Scientifique, Unités Mixtes de Recherche 3348, F-91405, Orsay, France
| | - Karl Ekwall
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
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47
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Nieminuszczy J, Broderick R, Bellani MA, Smethurst E, Schwab RA, Cherdyntseva V, Evmorfopoulou T, Lin YL, Minczuk M, Pasero P, Gagos S, Seidman MM, Niedzwiedz W. EXD2 Protects Stressed Replication Forks and Is Required for Cell Viability in the Absence of BRCA1/2. Mol Cell 2019; 75:605-619.e6. [PMID: 31255466 PMCID: PMC6695479 DOI: 10.1016/j.molcel.2019.05.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/15/2019] [Accepted: 05/17/2019] [Indexed: 12/15/2022]
Abstract
Accurate DNA replication is essential to preserve genomic integrity and prevent chromosomal instability-associated diseases including cancer. Key to this process is the cells' ability to stabilize and restart stalled replication forks. Here, we show that the EXD2 nuclease is essential to this process. EXD2 recruitment to stressed forks suppresses their degradation by restraining excessive fork regression. Accordingly, EXD2 deficiency leads to fork collapse, hypersensitivity to replication inhibitors, and genomic instability. Impeding fork regression by inactivation of SMARCAL1 or removal of RECQ1's inhibition in EXD2-/- cells restores efficient fork restart and genome stability. Moreover, purified EXD2 efficiently processes substrates mimicking regressed forks. Thus, this work identifies a mechanism underpinned by EXD2's nuclease activity, by which cells balance fork regression with fork restoration to maintain genome stability. Interestingly, from a clinical perspective, we discover that EXD2's depletion is synthetic lethal with mutations in BRCA1/2, implying a non-redundant role in replication fork protection.
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Affiliation(s)
| | | | - Marina A Bellani
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD, USA
| | | | | | - Veronica Cherdyntseva
- Laboratory of Genetics, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Theodora Evmorfopoulou
- Laboratory of Genetics, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Yea-Lih Lin
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Sarantis Gagos
- Laboratory of Genetics, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Michael M Seidman
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD, USA
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48
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Replication fork stalling elicits chromatin compaction for the stability of stalling replication forks. Proc Natl Acad Sci U S A 2019; 116:14563-14572. [PMID: 31262821 DOI: 10.1073/pnas.1821475116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
DNA replication forks in eukaryotic cells stall at a variety of replication barriers. Stalling forks require strict cellular regulations to prevent fork collapse. However, the mechanism underlying these cellular regulations is poorly understood. In this study, a cellular mechanism was uncovered that regulates chromatin structures to stabilize stalling forks. When replication forks stall, H2BK33, a newly identified acetylation site, is deacetylated and H3K9 trimethylated in the nucleosomes surrounding stalling forks, which results in chromatin compaction around forks. Acetylation-mimic H2BK33Q and its deacetylase clr6-1 mutations compromise this fork stalling-induced chromatin compaction, cause physical separation of replicative helicase and DNA polymerases, and significantly increase the frequency of stalling fork collapse. Furthermore, this fork stalling-induced H2BK33 deacetylation is independent of checkpoint. In summary, these results suggest that eukaryotic cells have developed a cellular mechanism that stabilizes stalling forks by targeting nucleosomes and inducing chromatin compaction around stalling forks. This mechanism is named the "Chromsfork" control: Chromatin Compaction Stabilizes Stalling Replication Forks.
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49
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Liddiard K, Ruis B, Kan Y, Cleal K, Ashelford KE, Hendrickson EA, Baird DM. DNA Ligase 1 is an essential mediator of sister chromatid telomere fusions in G2 cell cycle phase. Nucleic Acids Res 2019; 47:2402-2424. [PMID: 30590694 PMCID: PMC6411840 DOI: 10.1093/nar/gky1279] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 12/11/2018] [Accepted: 12/14/2018] [Indexed: 12/27/2022] Open
Abstract
Fusion of critically short or damaged telomeres is associated with the genomic rearrangements that support malignant transformation. We have demonstrated the fundamental contribution of DNA ligase 4-dependent classical non-homologous end-joining to long-range inter-chromosomal telomere fusions. In contrast, localized genomic recombinations initiated by sister chromatid fusion are predominantly mediated by alternative non-homologous end-joining activity that may employ either DNA ligase 3 or DNA ligase 1. In this study, we sought to discriminate the relative involvement of these ligases in sister chromatid telomere fusion through a precise genetic dissociation of functional activity. We have resolved an essential and non-redundant role for DNA ligase 1 in the fusion of sister chromatids bearing targeted double strand DNA breaks that is entirely uncoupled from its requisite engagement in DNA replication. Importantly, this fusogenic repair occurs in cells fully proficient for non-homologous end-joining and is not compensated by DNA ligases 3 or 4. The dual functions of DNA ligase 1 in replication and non-homologous end-joining uniquely position and capacitate this ligase for DNA repair at stalled replication forks, facilitating mitotic progression.
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Affiliation(s)
- Kate Liddiard
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Brian Ruis
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yinan Kan
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kez Cleal
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Kevin E Ashelford
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
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50
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Piazza A, Heyer WD. Homologous Recombination and the Formation of Complex Genomic Rearrangements. Trends Cell Biol 2019; 29:135-149. [PMID: 30497856 PMCID: PMC6402879 DOI: 10.1016/j.tcb.2018.10.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/28/2018] [Accepted: 10/29/2018] [Indexed: 12/13/2022]
Abstract
The maintenance of genome integrity involves multiple independent DNA damage avoidance and repair mechanisms. However, the origin and pathways of the focal chromosomal reshuffling phenomena collectively referred to as chromothripsis remain mechanistically obscure. We discuss here the role, mechanisms, and regulation of homologous recombination (HR) in the formation of simple and complex chromosomal rearrangements. We emphasize features of the recently characterized multi-invasion (MI)-induced rearrangement (MIR) pathway which uniquely amplifies the initial DNA damage. HR intermediates and cellular contexts that endanger genomic stability are discussed as well as the emerging roles of various classes of nucleases in the formation of genome rearrangements. Long-read sequencing and improved mapping of repeats should enable better appreciation of the significance of recombination in generating genomic rearrangements.
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Affiliation(s)
- Aurèle Piazza
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; Spatial Regulation of Genomes, Department of Genomes and Genetics, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 3525, Institut Pasteur, 75015 Paris, France
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA.
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