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Mashayekhi F, Ganje C, Caron MC, Heyza JR, Gao Y, Zeinali E, Fanta M, Li L, Ali J, Mersaoui SY, Schmidt JC, Godbout R, Masson JY, Weinfeld M, Ismail IH. PNKP safeguards stalled replication forks from nuclease-dependent degradation during replication stress. Cell Rep 2024; 43:115066. [PMID: 39671289 DOI: 10.1016/j.celrep.2024.115066] [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: 03/26/2024] [Revised: 09/04/2024] [Accepted: 11/22/2024] [Indexed: 12/15/2024] Open
Abstract
Uncontrolled degradation and collapse of stalled replication forks (RFs) are primary sources of genomic instability, yet the molecular mechanisms for protecting forks from degradation/collapse remain to be fully elaborated. Here, we show that polynucleotide kinase-phosphatase (PNKP) localizes at stalled forks and protects stalled forks from excessive degradation. The loss of PNKP results in nucleolytic degradation of nascent DNA at stalled RFs. This mechanism is different from the BRCA2-dependent fork protection pathway, which protects stalled forks from excessive MRE11-dependent nucleolytic degradation. Our research shows that hydroxyurea treatment leads to increased misincorporation of ribonucleotides in DNA, which in turn traps TOP1 on stalled RFs. We have also found that reducing the levels of TOP1 or TDP1 in cells can reverse the degradation of nascent DNA observed in PNKP-deficient cells. In summary, our data suggest that PNKP plays a role in maintaining the stability of stalled RFs.
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Affiliation(s)
- Fatemeh Mashayekhi
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Cassandra Ganje
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Marie-Christine Caron
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, 9 McMahon, Québec City, QC G1R 3S3, Canada
| | - Joshua R Heyza
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Yuandi Gao
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, 9 McMahon, Québec City, QC G1R 3S3, Canada
| | - Elham Zeinali
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Mesfin Fanta
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Lei Li
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Jana Ali
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Sofiane Yacine Mersaoui
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, 9 McMahon, Québec City, QC G1R 3S3, Canada
| | - Jens C Schmidt
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Roseline Godbout
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Jean-Yves Masson
- Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, 9 McMahon, Québec City, QC G1R 3S3, Canada
| | - Michael Weinfeld
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
| | - Ismail Hassan Ismail
- Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada; Biophysics Department, Faculty of Science, Cairo University, Giza 12613, Egypt.
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2
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Thomas R, Zaksauskaite R, Al-Kandari N, Hyde A, Abugable A, El-Khamisy S, van Eeden F. Second generation lethality in RNAseH2a knockout zebrafish. Nucleic Acids Res 2024; 52:11014-11028. [PMID: 39217460 PMCID: PMC11472149 DOI: 10.1093/nar/gkae725] [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: 12/20/2023] [Revised: 07/31/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024] Open
Abstract
Removal of ribonucleotides from DNA by RNaseH2 is essential for genome stability, and its impacted function causes the neurodegenerative disease, Aicardi Goutières Syndrome. We have created a zebrafish rnaseh2a mutant to model this process. Surprisingly, RNaseH2a knockouts show little phenotypic abnormality at adulthood in the first generation, unlike mouse knockout models, which are early embryonic lethal. However, the second generation offspring show reduced development, increased ribonucleotide incorporation and upregulation of key inflammatory markers, resulting in both maternal and paternal embryonic lethality. Thus, neither fathers or mothers can generate viable offspring even when crossed to wild-type partners. Despite their survival, rnaseh2a-/- adults show an accumulation of ribonucleotides in both the brain and testes that is not present in early development. Our data suggest that homozygotes possess RNaseH2 independent compensatory mechanisms that are inactive or overwhelmed by the inherited ribonucleotides in their offspring, or that zebrafish have a yet unknown tolerance mechanism. Additionally, we identify ribodysgenesis, the rapid removal of rNMPs and subsequently lethal fragmentation of DNA as responsible for maternal and paternal embryonic lethality.
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Affiliation(s)
- Ruth C Thomas
- Bateson Centre, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Ringaile Zaksauskaite
- Bateson Centre, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Norah Y Al-Kandari
- Bateson Centre, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Anne Cathrine Hyde
- Bateson Centre, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Arwa A Abugable
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
| | - Sherif F El-Khamisy
- Bateson Centre, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
- The Institute of Cancer Therapeutics, University of Bradford, BD7 1DP, UK
| | - Freek J van Eeden
- Bateson Centre, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Healthy Lifespan Institute, Sheffield Institute for Neuroscience, University of Sheffield, Sheffield S10 2TN, UK
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3
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Williams JS, Lujan SA, Arana ME, Burkholder AB, Tumbale PP, Williams RS, Kunkel TA. High fidelity DNA ligation prevents single base insertions in the yeast genome. Nat Commun 2024; 15:8730. [PMID: 39379399 PMCID: PMC11461686 DOI: 10.1038/s41467-024-53063-1] [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: 04/24/2024] [Accepted: 09/30/2024] [Indexed: 10/10/2024] Open
Abstract
Finalization of eukaryotic nuclear DNA replication relies on DNA ligase 1 (LIG1) to seal DNA nicks generated during Okazaki Fragment Maturation (OFM). Using a mutational reporter in Saccharomyces cerevisiae, we previously showed that mutation of the high-fidelity magnesium binding site of LIG1Cdc9 strongly increases the rate of single-base insertions. Here we show that this rate is increased across the nuclear genome, that it is synergistically increased by concomitant loss of DNA mismatch repair (MMR), and that the additions occur in highly specific sequence contexts. These discoveries are all consistent with incorporation of an extra base into the nascent lagging DNA strand that can be corrected by MMR following mutagenic ligation by the Cdc9-EEAA variant. There is a strong preference for insertion of either dGTP or dTTP into 3-5 base pair mononucleotide sequences with stringent flanking nucleotide requirements. The results reveal unique LIG1Cdc9-dependent mutational motifs where high fidelity DNA ligation of a subset of OFs is critical for preventing mutagenesis across the genome.
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Affiliation(s)
- Jessica S Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Scott A Lujan
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Mercedes E Arana
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Adam B Burkholder
- Office of Environmental Science Cyberinfrastructure, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Percy P Tumbale
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA.
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4
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Wojtaszek JL, Williams RS. From the TOP: Formation, recognition and resolution of topoisomerase DNA protein crosslinks. DNA Repair (Amst) 2024; 142:103751. [PMID: 39180935 PMCID: PMC11404304 DOI: 10.1016/j.dnarep.2024.103751] [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: 04/22/2024] [Revised: 08/07/2024] [Accepted: 08/12/2024] [Indexed: 08/27/2024]
Abstract
Since the report of "DNA untwisting" activity in 1972, ∼50 years of research has revealed seven topoisomerases in humans (TOP1, TOP1mt, TOP2α, TOP2β, TOP3α, TOP3β and Spo11). These conserved regulators of DNA topology catalyze controlled breakage to the DNA backbone to relieve the torsional stress that accumulates during essential DNA transactions including DNA replication, transcription, and DNA repair. Each topoisomerase-catalyzed reaction involves the formation of a topoisomerase cleavage complex (TOPcc), a covalent protein-DNA reaction intermediate formed between the DNA phosphodiester backbone and a topoisomerase catalytic tyrosine residue. A variety of perturbations to topoisomerase reaction cycles can trigger failure of the enzyme to re-ligate the broken DNA strand(s), thereby generating topoisomerase DNA-protein crosslinks (TOP-DPC). TOP-DPCs pose unique threats to genomic integrity. These complex lesions are comprised of structurally diverse protein components covalently linked to genomic DNA, which are bulky DNA adducts that can directly impact progression of the transcription and DNA replication apparatus. A variety of genome maintenance pathways have evolved to recognize and resolve TOP-DPCs. Eukaryotic cells harbor tyrosyl DNA phosphodiesterases (TDPs) that directly reverse 3'-phosphotyrosyl (TDP1) and 5'-phoshotyrosyl (TDP2) protein-DNA linkages. The broad specificity Mre11-Rad50-Nbs1 and APE2 nucleases are also critical for mitigating topoisomerase-generated DNA damage. These DNA-protein crosslink metabolizing enzymes are further enabled by proteolytic degradation, with the proteasome, Spartan, GCNA, Ddi2, and FAM111A proteases implicated thus far. Strategies to target, unfold, and degrade the protein component of TOP-DPCs have evolved as well. Here we survey mechanisms for addressing Topoisomerase 1 (TOP1) and Topoisomerase 2 (TOP2) DPCs, highlighting systems for which molecular structure information has illuminated function of these critical DNA damage response pathways.
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Affiliation(s)
- Jessica L Wojtaszek
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, United States
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, United States.
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5
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Balu KE, Tang Q, Almohdar D, Ratcliffe J, Kalaycioğlu M, Çağlayan M. Structures of LIG1 uncover the mechanism of sugar discrimination against 5'-RNA-DNA junctions during ribonucleotide excision repair. J Biol Chem 2024; 300:107688. [PMID: 39159820 PMCID: PMC11418127 DOI: 10.1016/j.jbc.2024.107688] [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: 05/28/2024] [Revised: 08/06/2024] [Accepted: 08/07/2024] [Indexed: 08/21/2024] Open
Abstract
Ribonucleotides in DNA cause several types of genome instability and can be removed by ribonucleotide excision repair (RER) that is finalized by DNA ligase 1 (LIG1). However, the mechanism by which LIG1 discriminates the RER intermediate containing a 5'-RNA-DNA lesion generated by RNase H2-mediated cleavage of ribonucleotides at atomic resolution remains unknown. Here, we determine X-ray structures of LIG1/5'-rG:C at the initial step of ligation where AMP is bound to the active site of the ligase and uncover a large conformational change downstream the nick resulting in a shift at Arg(R)871 residue in the Adenylation domain of the ligase. Furthermore, we demonstrate a diminished ligation of the nick DNA substrate with a 5'-ribonucleotide in comparison to an efficient end joining of the nick substrate with a 3'-ribonucleotide by LIG1. Finally, our results demonstrate that mutations at the active site residues of the ligase and LIG1 disease-associated variants significantly impact the ligation efficiency of RNA-DNA heteroduplexes harboring "wrong" sugar at 3'- or 5'-end of nick. Collectively, our findings provide a novel atomic insight into proficient sugar discrimination by LIG1 during the processing of the most abundant form of DNA damage in cells, genomic ribonucleotides, during the initial step of the RER pathway.
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Affiliation(s)
- Kanal Elamparithi Balu
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Qun Tang
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Danah Almohdar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Jacob Ratcliffe
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Mustafa Kalaycioğlu
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Melike Çağlayan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA.
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6
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Bugallo A, Segurado M. Unraveling the complexity of asymmetric DNA replication: Advancements in ribonucleotide mapping techniques and beyond. Genomics 2024; 116:110908. [PMID: 39106913 DOI: 10.1016/j.ygeno.2024.110908] [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: 04/12/2024] [Revised: 07/18/2024] [Accepted: 07/31/2024] [Indexed: 08/09/2024]
Abstract
DNA replication is a fundamental process for cell proliferation, governed by intricate mechanisms involving leading and lagging strand synthesis. In eukaryotes, canonical DNA replication occurs during the S phase of the cell cycle, facilitated by various components of the replicative machinery at sites known as replication origins. Leading and lagging strands exhibit distinct replication dynamics, with leading strand replication being relatively straightforward compared to the complex synthesis of lagging strands involving Okazaki fragment maturation. Central to DNA synthesis are DNA polymerases, with Polα, Polε, and Polδ playing pivotal roles, each specializing in specific tasks during replication. Notably, leading and lagging strands are replicated by different polymerases, contributing to the division of labor in DNA replication. Understanding the enzymology of asymmetric DNA replication has been challenging, with methods relying on ribonucleotide incorporation and next-generation sequencing techniques offering comprehensive insights. These methodologies, such as HydEn-seq, PU-seq, ribose-seq, and emRiboSeq, offer insights into polymerase activity and strand synthesis, aiding in understanding DNA replication dynamics. Recent advancements include novel conditional mutants for ribonucleotide excision repair, enzymatic cleavage alternatives, and unified pipelines for data analysis. Further developments in adapting techniques to different organisms, studying non-canonical polymerases, and exploring new sequencing platforms hold promise for expanding our understanding of DNA replication dynamics. Integrating strand-specific information into single-cell studies could offer novel insights into enzymology, opening avenues for future research and applications in repair and replication biology.
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Affiliation(s)
- Alberto Bugallo
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Mónica Segurado
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain; Departamento de Microbiología y Genética (USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain.
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7
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Bugallo A, Sánchez M, Fernández-García M, Segurado M. S-phase checkpoint prevents leading strand degradation from strand-associated nicks at stalled replication forks. Nucleic Acids Res 2024; 52:5121-5137. [PMID: 38520409 PMCID: PMC11109941 DOI: 10.1093/nar/gkae192] [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: 11/06/2023] [Revised: 03/01/2024] [Accepted: 03/07/2024] [Indexed: 03/25/2024] Open
Abstract
The S-phase checkpoint is involved in coupling DNA unwinding with nascent strand synthesis and is critical to maintain replication fork stability in conditions of replicative stress. However, its role in the specific regulation of leading and lagging strands at stalled forks is unclear. By conditionally depleting RNaseH2 and analyzing polymerase usage genome-wide, we examine the enzymology of DNA replication during a single S-phase in the presence of replicative stress and show that there is a differential regulation of lagging and leading strands. In checkpoint proficient cells, lagging strand replication is down-regulated through an Elg1-dependent mechanism. Nevertheless, when checkpoint function is impaired we observe a defect specifically at the leading strand, which was partially dependent on Exo1 activity. Further, our genome-wide mapping of DNA single-strand breaks reveals that strand discontinuities highly accumulate at the leading strand in HU-treated cells, whose dynamics are affected by checkpoint function and Exo1 activity. Our data reveal an unexpected role of Exo1 at the leading strand and support a model of fork stabilization through prevention of unrestrained Exo1-dependent resection of leading strand-associated nicks after fork stalling.
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Affiliation(s)
- Alberto Bugallo
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Mar Sánchez
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - María Fernández-García
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Mónica Segurado
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
- Departamento de Microbiología y Genética (USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
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8
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Yang J, Sun M, Ran Z, Yang T, Kundnani DL, Storici F, Xu P. rNMPID: a database for riboNucleoside MonoPhosphates in DNA. BIOINFORMATICS ADVANCES 2024; 4:vbae063. [PMID: 38736683 PMCID: PMC11088741 DOI: 10.1093/bioadv/vbae063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/27/2024] [Accepted: 05/07/2024] [Indexed: 05/14/2024]
Abstract
Motivation Ribonucleoside monophosphates (rNMPs) are the most abundant non-standard nucleotides embedded in genomic DNA. If the presence of rNMP in DNA cannot be controlled, it can lead to genome instability. The actual regulatory functions of rNMPs in DNA remain mainly unknown. Considering the association between rNMP embedment and various diseases and cancer, the phenomenon of rNMP embedment in DNA has become a prominent area of research in recent years. Results We introduce the rNMPID database, which is the first database revealing rNMP-embedment characteristics, strand bias, and preferred incorporation patterns in the genomic DNA of samples from bacterial to human cells of different genetic backgrounds. The rNMPID database uses datasets generated by different rNMP-mapping techniques. It provides the researchers with a solid foundation to explore the features of rNMP embedded in the genomic DNA of multiple sources, and their association with cellular functions, and, in future, disease. It also significantly benefits researchers in the fields of genetics and genomics who aim to integrate their studies with the rNMP-embedment data. Availability and implementation rNMPID is freely accessible on the web at https://www.rnmpid.org.
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Affiliation(s)
- Jingcheng Yang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Human Phenome Institute, and Shanghai Cancer Center, Fudan University, Shanghai 200438, China
- Greater Bay Area Institute of Precision Medicine, Guangzhou, Guangdong 511462, China
| | - Mo Sun
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Zihan Ran
- Department of Research, Shanghai University of Medicine & Health Sciences Affiliated Zhoupu Hospital, Shanghai 201318, China
- Inspection and Quarantine Department, The College of Medical Technology, Shanghai University of Medicine & Health Sciences, Shanghai 201318, China
| | - Taehwan Yang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Deepali L Kundnani
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Francesca Storici
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Penghao Xu
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
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9
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Piguet B, Houseley J. Transcription as source of genetic heterogeneity in budding yeast. Yeast 2024; 41:171-185. [PMID: 38196235 DOI: 10.1002/yea.3926] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 12/10/2023] [Accepted: 12/20/2023] [Indexed: 01/11/2024] Open
Abstract
Transcription presents challenges to genome stability both directly, by altering genome topology and exposing single-stranded DNA to chemical insults and nucleases, and indirectly by introducing obstacles to the DNA replication machinery. Such obstacles include the RNA polymerase holoenzyme itself, DNA-bound regulatory factors, G-quadruplexes and RNA-DNA hybrid structures known as R-loops. Here, we review the detrimental impacts of transcription on genome stability in budding yeast, as well as the mitigating effects of transcription-coupled nucleotide excision repair and of systems that maintain DNA replication fork processivity and integrity. Interactions between DNA replication and transcription have particular potential to induce mutation and structural variation, but we conclude that such interactions must have only minor effects on DNA replication by the replisome with little if any direct mutagenic outcome. However, transcription can significantly impair the fidelity of replication fork rescue mechanisms, particularly Break Induced Replication, which is used to restart collapsed replication forks when other means fail. This leads to de novo mutations, structural variation and extrachromosomal circular DNA formation that contribute to genetic heterogeneity, but only under particular conditions and in particular genetic contexts, ensuring that the bulk of the genome remains extremely stable despite the seemingly frequent interactions between transcription and DNA replication.
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10
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Conti BA, Ruiz PD, Broton C, Blobel NJ, Kottemann MC, Sridhar S, Lach FP, Wiley TF, Sasi NK, Carroll T, Smogorzewska A. RTF2 controls replication repriming and ribonucleotide excision at the replisome. Nat Commun 2024; 15:1943. [PMID: 38431617 PMCID: PMC10908796 DOI: 10.1038/s41467-024-45947-z] [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: 11/09/2023] [Accepted: 02/07/2024] [Indexed: 03/05/2024] Open
Abstract
DNA replication through a challenging genomic landscape is coordinated by the replisome, which must adjust to local conditions to provide appropriate replication speed and respond to lesions that hinder its progression. We have previously shown that proteasome shuttle proteins, DNA Damage Inducible 1 and 2 (DDI1/2), regulate Replication Termination Factor 2 (RTF2) levels at stalled replisomes, allowing fork stabilization and restart. Here, we show that during unperturbed replication, RTF2 regulates replisome localization of RNase H2, a heterotrimeric enzyme that removes RNA from RNA-DNA heteroduplexes. RTF2, like RNase H2, is essential for mammalian development and maintains normal replication speed. However, persistent RTF2 and RNase H2 at stalled replication forks prevent efficient replication restart, which is dependent on PRIM1, the primase component of DNA polymerase α-primase. Our data show a fundamental need for RTF2-dependent regulation of replication-coupled ribonucleotide removal and reveal the existence of PRIM1-mediated direct replication restart in mammalian cells.
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Affiliation(s)
- Brooke A Conti
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Penelope D Ruiz
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Cayla Broton
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Nicolas J Blobel
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Molly C Kottemann
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Sunandini Sridhar
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Francis P Lach
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Tom F Wiley
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA
| | - Nanda K Sasi
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, 10065, USA
| | - Thomas Carroll
- Bioinformatics, The Rockefeller University, New York, NY, 10065, USA
| | - Agata Smogorzewska
- Laboratory of Genome Maintenance, The Rockefeller University, New York, NY, 10065, USA.
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11
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Milano L, Gautam A, Caldecott KW. DNA damage and transcription stress. Mol Cell 2024; 84:70-79. [PMID: 38103560 DOI: 10.1016/j.molcel.2023.11.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023]
Abstract
Genome damage and transcription are intimately linked. Tens to hundreds of thousands of DNA lesions arise in each cell each day, many of which can directly or indirectly impede transcription. Conversely, the process of gene expression is itself a source of endogenous DNA lesions as a result of the susceptibility of single-stranded DNA to damage, conflicts with the DNA replication machinery, and engagement by cells of topoisomerases and base excision repair enzymes to regulate the initiation and progression of gene transcription. Although such processes are tightly regulated and normally accurate, on occasion, they can become abortive and leave behind DNA breaks that can drive genome rearrangements, instability, or cell death.
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Affiliation(s)
- Larissa Milano
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
| | - Amit Gautam
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
| | - Keith W Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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12
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Ahmad T, Kawasumi R, Taniguchi T, Abe T, Terada K, Tsuda M, Shimizu N, Tsurimoto T, Takeda S, Hirota K. The proofreading exonuclease of leading-strand DNA polymerase epsilon prevents replication fork collapse at broken template strands. Nucleic Acids Res 2023; 51:12288-12302. [PMID: 37944988 PMCID: PMC10711444 DOI: 10.1093/nar/gkad999] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 11/12/2023] Open
Abstract
Leading-strand DNA replication by polymerase epsilon (Polϵ) across single-strand breaks (SSBs) causes single-ended double-strand breaks (seDSBs), which are repaired via homology-directed repair (HDR) and suppressed by fork reversal (FR). Although previous studies identified many molecules required for hydroxyurea-induced FR, FR at seDSBs is poorly understood. Here, we identified molecules that specifically mediate FR at seDSBs. Because FR at seDSBs requires poly(ADP ribose)polymerase 1 (PARP1), we hypothesized that seDSB/FR-associated molecules would increase tolerance to camptothecin (CPT) but not the PARP inhibitor olaparib, even though both anti-cancer agents generate seDSBs. Indeed, we uncovered that Polϵ exonuclease and CTF18, a Polϵ cofactor, increased tolerance to CPT but not olaparib. To explore potential functional interactions between Polϵ exonuclease, CTF18, and PARP1, we created exonuclease-deficient POLE1exo-/-, CTF18-/-, PARP1-/-, CTF18-/-/POLE1exo-/-, PARP1-/-/POLE1exo-/-, and CTF18-/-/PARP1-/- cells. Epistasis analysis indicated that Polϵ exonuclease and CTF18 were interdependent and required PARP1 for CPT tolerance. Remarkably, POLE1exo-/- and HDR-deficient BRCA1-/- cells exhibited similar CPT sensitivity. Moreover, combining POLE1exo-/- with BRCA1-/- mutations synergistically increased CPT sensitivity. In conclusion, the newly identified PARP1-CTF18-Polϵ exonuclease axis and HDR act independently to prevent fork collapse at seDSBs. Olaparib inhibits this axis, explaining the pronounced cytotoxic effects of olaparib on HDR-deficient cells.
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Affiliation(s)
- Tasnim Ahmad
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Ryotaro Kawasumi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Tomoya Taniguchi
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Takuya Abe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
| | - Kazuhiro Terada
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masataka Tsuda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
- Program of Mathematical and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501, Japan
| | - Naoto Shimizu
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto 606-8501, Japan
- Program of Mathematical and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Toshiki Tsurimoto
- Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Shunichi Takeda
- Shenzhen University, School of Medicine, Shenzhen, Guangdong 518060, China
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo 192-0397, Japan
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13
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Heuzé J, Kemiha S, Barthe A, Vilarrubias AT, Aouadi E, Aiello U, Libri D, Lin Y, Lengronne A, Poli J, Pasero P. RNase H2 degrades toxic RNA:DNA hybrids behind stalled forks to promote replication restart. EMBO J 2023; 42:e113104. [PMID: 37855233 PMCID: PMC10690446 DOI: 10.15252/embj.2022113104] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 09/27/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023] Open
Abstract
R-loops represent a major source of replication stress, but the mechanism by which these structures impede fork progression remains unclear. To address this question, we monitored fork progression, arrest, and restart in Saccharomyces cerevisiae cells lacking RNase H1 and H2, two enzymes responsible for degrading RNA:DNA hybrids. We found that while RNase H-deficient cells could replicate their chromosomes normally under unchallenged growth conditions, their replication was impaired when exposed to hydroxyurea (HU) or methyl methanesulfonate (MMS). Treated cells exhibited increased levels of RNA:DNA hybrids at stalled forks and were unable to generate RPA-coated single-stranded (ssDNA), an important postreplicative intermediate in resuming replication. Similar impairments in nascent DNA resection and ssDNA formation at HU-arrested forks were observed in human cells lacking RNase H2. However, fork resection was fully restored by addition of triptolide, an inhibitor of transcription that induces RNA polymerase degradation. Taken together, these data indicate that RNA:DNA hybrids not only act as barriers to replication forks, but also interfere with postreplicative fork repair mechanisms if not promptly degraded by RNase H.
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Affiliation(s)
- Jonathan Heuzé
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Samira Kemiha
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Antoine Barthe
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Alba Torán Vilarrubias
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Elyès Aouadi
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Umberto Aiello
- Université Paris Cité, CNRS, Institut Jacques MonodParisFrance
- Department of GeneticsStanford UniversityStanfordCAUSA
| | - Domenico Libri
- Université Paris Cité, CNRS, Institut Jacques MonodParisFrance
- Present address:
Institut de Génétique Moléculaire de MontpellierUniversité de Montpellier, CNRSMontpellierFrance
| | - Yea‐Lih Lin
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Armelle Lengronne
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Jérôme Poli
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
- Institut Universitaire de France (IUF)ParisFrance
| | - Philippe Pasero
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
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14
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Tsao N, Ashour ME, Mosammaparast N. How RNA impacts DNA repair. DNA Repair (Amst) 2023; 131:103564. [PMID: 37776841 PMCID: PMC11232704 DOI: 10.1016/j.dnarep.2023.103564] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 10/02/2023]
Abstract
The central dogma of molecular biology posits that genetic information flows unidirectionally, from DNA, to RNA, and finally to protein. However, this directionality is broken in some cases, such as reverse transcription where RNA is converted to DNA by retroviruses and certain transposable elements. Our genomes have evolved and adapted to the presence of reverse transcription. Similarly, our genome is continuously maintained by several repair pathways to reverse damage due to various endogenous and exogenous sources. More recently, evidence has revealed that RNA, while in certain contexts may be detrimental for genome stability, is involved in promoting certain types of DNA repair. Depending on the pathway in question, the size of these DNA repair-associated RNAs range from one or a few ribonucleotides to long fragments of RNA. Moreover, RNA is highly modified, and RNA modifications have been revealed to be functionally associated with specific DNA repair pathways. In this review, we highlight aspects of this unexpected layer of genomic maintenance, demonstrating how RNA may influence DNA integrity.
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Affiliation(s)
- Ning Tsao
- Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Mohamed E Ashour
- Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Nima Mosammaparast
- Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA.
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15
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Conti BA, Ruiz PD, Broton C, Blobel NJ, Kottemann MC, Sridhar S, Lach FP, Wiley T, Sasi NK, Carroll T, Smogorzewska A. RTF2 controls replication repriming and ribonucleotide excision at the replisome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.13.532415. [PMID: 36993543 PMCID: PMC10054921 DOI: 10.1101/2023.03.13.532415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Genetic information is duplicated via the highly regulated process of DNA replication. The machinery coordinating this process, the replisome, encounters many challenges, including replication fork-stalling lesions that threaten the accurate and timely transmission of genetic information. Cells have multiple mechanisms to repair or bypass lesions that would otherwise compromise DNA replication1,2. We have previously shown that proteasome shuttle proteins, DNA Damage Inducible 1 and 2 (DDI1/2) function to regulate Replication Termination Factor 2 (RTF2) at the stalled replisome, allowing for replication fork stabilization and restart3. Here we show that RTF2 regulates replisome localization of RNase H2, a heterotrimeric enzyme responsible for removing RNA in the context of RNA-DNA heteroduplexes4-6. We show that during unperturbed DNA replication, RTF2, like RNase H2, is required to maintain normal replication fork speeds. However, persistent RTF2 and RNase H2 at stalled replication forks compromises the replication stress response, preventing efficient replication restart. Such restart is dependent on PRIM1, the primase component of DNA polymerase α-primase. Our data show a fundamental need for regulation of replication-coupled ribonucleotide incorporation during normal replication and the replication stress response that is achieved through RTF2. We also provide evidence for PRIM1 function in direct replication restart following replication stress in mammalian cells.
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Affiliation(s)
- Brooke A Conti
- Laboratory of Genome Maintenance, The Rockefeller University
| | - Penelope D Ruiz
- Laboratory of Genome Maintenance, The Rockefeller University
| | - Cayla Broton
- Laboratory of Genome Maintenance, The Rockefeller University
| | | | | | | | - Francis P Lach
- Laboratory of Genome Maintenance, The Rockefeller University
| | - Tom Wiley
- Laboratory of Genome Maintenance, The Rockefeller University
| | - Nanda K Sasi
- Laboratory for Cell Biology and Genetics, The Rockefeller University
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16
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Schindler N, Tonn M, Kellner V, Fung JJ, Lockhart A, Vydzhak O, Juretschke T, Möckel S, Beli P, Khmelinskii A, Luke B. Genetic requirements for repair of lesions caused by single genomic ribonucleotides in S phase. Nat Commun 2023; 14:1227. [PMID: 36869098 PMCID: PMC9984532 DOI: 10.1038/s41467-023-36866-6] [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: 06/12/2022] [Accepted: 02/21/2023] [Indexed: 03/05/2023] Open
Abstract
Single ribonucleoside monophosphates (rNMPs) are transiently present in eukaryotic genomes. The RNase H2-dependent ribonucleotide excision repair (RER) pathway ensures error-free rNMP removal. In some pathological conditions, rNMP removal is impaired. If these rNMPs hydrolyze during, or prior to, S phase, toxic single-ended double-strand breaks (seDSBs) can occur upon an encounter with replication forks. How such rNMP-derived seDSB lesions are repaired is unclear. We expressed a cell cycle phase restricted allele of RNase H2 to nick at rNMPs in S phase and study their repair. Although Top1 is dispensable, the RAD52 epistasis group and Rtt101Mms1-Mms22 dependent ubiquitylation of histone H3 become essential for rNMP-derived lesion tolerance. Consistently, loss of Rtt101Mms1-Mms22 combined with RNase H2 dysfunction leads to compromised cellular fitness. We refer to this repair pathway as nick lesion repair (NLR). The NLR genetic network may have important implications in the context of human pathologies.
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Affiliation(s)
- Natalie Schindler
- Johannes Gutenberg University Mainz, Institute for Developmental Neurology (IDN), Biozentrum 1, Hanns-Dieter-Hüsch-Weg 15, 55128, Mainz, Germany.
| | - Matthias Tonn
- Johannes Gutenberg University Mainz, Institute for Developmental Neurology (IDN), Biozentrum 1, Hanns-Dieter-Hüsch-Weg 15, 55128, Mainz, Germany
| | - Vanessa Kellner
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany.,Department of Biology, New York University, New York, NY, USA
| | - Jia Jun Fung
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
| | - Arianna Lockhart
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
| | - Olga Vydzhak
- Johannes Gutenberg University Mainz, Institute for Developmental Neurology (IDN), Biozentrum 1, Hanns-Dieter-Hüsch-Weg 15, 55128, Mainz, Germany
| | - Thomas Juretschke
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
| | - Stefanie Möckel
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
| | - Petra Beli
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
| | - Anton Khmelinskii
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany
| | - Brian Luke
- Johannes Gutenberg University Mainz, Institute for Developmental Neurology (IDN), Biozentrum 1, Hanns-Dieter-Hüsch-Weg 15, 55128, Mainz, Germany. .,Institute of Molecular Biology (IMB), Ackermannweg 4, 55128, Mainz, Germany.
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17
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McMahon A, Zhao J, Yan S. APE2: catalytic function and synthetic lethality draw attention as a cancer therapy target. NAR Cancer 2023; 5:zcad006. [PMID: 36755963 PMCID: PMC9900424 DOI: 10.1093/narcan/zcad006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/17/2023] [Accepted: 01/20/2023] [Indexed: 02/08/2023] Open
Abstract
AP endonuclease 2 (APE2, APEX2 or APN2) is an emerging critical protein involved in genome and epigenome integrity. Whereas its catalytic function as a nuclease in DNA repair is widely accepted, recent studies have elucidated the function and mechanism of APE2 in the immune response and DNA damage response. Several genome-wide screens have identified APE2 as a synthetic lethal target for deficiencies of BRCA1, BRCA2 or TDP1 in cancer cells. Due to its overexpression in several cancer types, APE2 is proposed as an oncogene and could serve as prognostic marker of overall survival of cancer treatment. However, it remains to be discovered whether and how APE2 catalytic function and synthetic lethality can be modulated and manipulated as a cancer therapy target. In this review, we provide a current understanding of alterations and expression of APE2 in cancer, the function of APE2 in the immune response, and mechanisms of APE2 in ATR/Chk1 DNA damage response. We also summarize the role of APE2 in DNA repair pathways in the removal of heterogenous and complexed 3'-termini and MMEJ. Finally, we provide an updated perspective on how APE2 may be targeted for cancer therapy and future directions of APE2 studies in cancer biology.
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Affiliation(s)
- Anne McMahon
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Jianjun Zhao
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
- School of Data Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
- Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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18
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Primer terminal ribonucleotide alters the active site dynamics of DNA polymerase η and reduces DNA synthesis fidelity. J Biol Chem 2023; 299:102938. [PMID: 36702254 PMCID: PMC9976465 DOI: 10.1016/j.jbc.2023.102938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 01/25/2023] Open
Abstract
DNA polymerases catalyze DNA synthesis with high efficiency, which is essential for all life. Extensive kinetic and structural efforts have been executed in exploring mechanisms of DNA polymerases, surrounding their kinetic pathway, catalytic mechanisms, and factors that dictate polymerase fidelity. Recent time-resolved crystallography studies on DNA polymerase η (Pol η) and β have revealed essential transient events during the DNA synthesis reaction, such as mechanisms of primer deprotonation, separated roles of the three metal ions, and conformational changes that disfavor incorporation of the incorrect substrate. DNA-embedded ribonucleotides (rNs) are the most common lesion on DNA and a major threat to genome integrity. While kinetics of rN incorporation has been explored and structural studies have revealed that DNA polymerases have a steric gate that destabilizes ribonucleotide triphosphate binding, the mechanism of extension upon rN addition remains poorly characterized. Using steady-state kinetics, static and time-resolved X-ray crystallography with Pol η as a model system, we showed that the extra hydroxyl group on the primer terminus does alter the dynamics of the polymerase active site as well as the catalysis and fidelity of DNA synthesis. During rN extension, Pol η error incorporation efficiency increases significantly across different sequence contexts. Finally, our systematic structural studies suggest that the rN at the primer end improves primer alignment and reduces barriers in C2'-endo to C3'-endo sugar conformational change. Overall, our work provides further mechanistic insights into the effects of rN incorporation on DNA synthesis.
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19
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Zhao H, Hartono SR, de Vera KMF, Yu Z, Satchi K, Zhao T, Sciammas R, Sanz L, Chédin F, Barlow J. Senataxin and RNase H2 act redundantly to suppress genome instability during class switch recombination. eLife 2022; 11:e78917. [PMID: 36542058 PMCID: PMC9771370 DOI: 10.7554/elife.78917] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 11/17/2022] [Indexed: 12/24/2022] Open
Abstract
Class switch recombination generates distinct antibody isotypes critical to a robust adaptive immune system, and defects are associated with autoimmune disorders and lymphomagenesis. Transcription is required during class switch recombination to recruit the cytidine deaminase AID-an essential step for the formation of DNA double-strand breaks-and strongly induces the formation of R loops within the immunoglobulin heavy-chain locus. However, the impact of R loops on double-strand break formation and repair during class switch recombination remains unclear. Here, we report that cells lacking two enzymes involved in R loop removal-senataxin and RNase H2-exhibit increased R loop formation and genome instability at the immunoglobulin heavy-chain locus without impacting its transcriptional activity, AID recruitment, or class switch recombination efficiency. Senataxin and RNase H2-deficient cells also exhibit increased insertion mutations at switch junctions, a hallmark of alternative end joining. Importantly, these phenotypes were not observed in cells lacking senataxin or RNase H2B alone. We propose that senataxin acts redundantly with RNase H2 to mediate timely R loop removal, promoting efficient repair while suppressing AID-dependent genome instability and insertional mutagenesis.
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Affiliation(s)
- Hongchang Zhao
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
| | - Stella R Hartono
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | | | - Zheyuan Yu
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
- Graduate Group in Biostatistics, University of California, DavisDavisUnited States
| | - Krishni Satchi
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
| | - Tracy Zhao
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
| | - Roger Sciammas
- Center for Immunology and Infectious Diseases, University of California, DavisDavisUnited States
| | - Lionel Sanz
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Jacqueline Barlow
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
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20
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Molecular basis for processing of topoisomerase 1-triggered DNA damage by Apn2/APE2. Cell Rep 2022; 41:111448. [DOI: 10.1016/j.celrep.2022.111448] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 07/21/2022] [Accepted: 09/13/2022] [Indexed: 11/18/2022] Open
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21
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Sarni D, Barroso S, Shtrikman A, Irony-Tur Sinai M, Oren YS, Aguilera A, Kerem B. Topoisomerase 1-dependent R-loop deficiency drives accelerated replication and genomic instability. Cell Rep 2022; 40:111397. [PMID: 36170822 PMCID: PMC9532845 DOI: 10.1016/j.celrep.2022.111397] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 06/26/2022] [Accepted: 08/31/2022] [Indexed: 11/29/2022] Open
Abstract
DNA replication is a complex process tightly regulated to ensure faithful genome duplication, and its perturbation leads to DNA damage and genomic instability. Replication stress is commonly associated with slow and stalled replication forks. Recently, accelerated replication has emerged as a non-canonical form of replication stress. However, the molecular basis underlying fork acceleration is largely unknown. Here, we show that mutated HRAS activation leads to increased topoisomerase 1 (TOP1) expression, causing aberrant replication fork acceleration and DNA damage by decreasing RNA-DNA hybrids or R-loops. In these cells, restoration of TOP1 expression or mild replication inhibition rescues the perturbed replication and reduces DNA damage. Furthermore, TOP1 or RNaseH1 overexpression induces accelerated replication and DNA damage, highlighting the importance of TOP1 equilibrium in regulating R-loop homeostasis to ensure faithful DNA replication and genome integrity. Altogether, our results dissect a mechanism of oncogene-induced DNA damage by aberrant replication fork acceleration. Increased TOP1 expression by mutated RAS reduces R loops Low R-loop levels promote accelerated replication and DNA damage TOP1 restoration or mild replication inhibition rescue DNA acceleration and damage High TOP1 expression is associated with replication mutagenesis in cancer
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Affiliation(s)
- Dan Sarni
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem 91904, Israel
| | - Sonia Barroso
- Department of Genome Biology, Andalusian Center of Molecular Biology and Regenerative Medicine CABIMER, Seville Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Alon Shtrikman
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem 91904, Israel
| | - Michal Irony-Tur Sinai
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem 91904, Israel
| | - Yifat S Oren
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem 91904, Israel
| | - Andrés Aguilera
- Department of Genome Biology, Andalusian Center of Molecular Biology and Regenerative Medicine CABIMER, Seville Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Batsheva Kerem
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem 91904, Israel.
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22
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Cristini A, Tellier M, Constantinescu F, Accalai C, Albulescu LO, Heiringhoff R, Bery N, Sordet O, Murphy S, Gromak N. RNase H2, mutated in Aicardi-Goutières syndrome, resolves co-transcriptional R-loops to prevent DNA breaks and inflammation. Nat Commun 2022; 13:2961. [PMID: 35618715 PMCID: PMC9135716 DOI: 10.1038/s41467-022-30604-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 05/10/2022] [Indexed: 11/29/2022] Open
Abstract
RNase H2 is a specialized enzyme that degrades RNA in RNA/DNA hybrids and deficiency of this enzyme causes a severe neuroinflammatory disease, Aicardi Goutières syndrome (AGS). However, the molecular mechanism underlying AGS is still unclear. Here, we show that RNase H2 is associated with a subset of genes, in a transcription-dependent manner where it interacts with RNA Polymerase II. RNase H2 depletion impairs transcription leading to accumulation of R-loops, structures that comprise RNA/DNA hybrids and a displaced DNA strand, mainly associated with short and intronless genes. Importantly, accumulated R-loops are processed by XPG and XPF endonucleases which leads to DNA damage and activation of the immune response, features associated with AGS. Consequently, we uncover a key role for RNase H2 in the transcription of human genes by maintaining R-loop homeostasis. Our results provide insight into the mechanistic contribution of R-loops to AGS pathogenesis.
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Affiliation(s)
- Agnese Cristini
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Michael Tellier
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Flavia Constantinescu
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Clelia Accalai
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Laura Oana Albulescu
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Robin Heiringhoff
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Nicolas Bery
- Weatherall Institute of Molecular Medicine, MRC Molecular Haematology Unit, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS, UK
| | - Olivier Sordet
- Cancer Research Center of Toulouse, INSERM, Université de Toulouse, Université Toulouse III Paul Sabatier, CNRS, 31037, Toulouse, France
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
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23
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Carvalho G, Repolês BM, Mendes I, Wanrooij PH. Mitochondrial DNA Instability in Mammalian Cells. Antioxid Redox Signal 2022; 36:885-905. [PMID: 34015960 PMCID: PMC9127837 DOI: 10.1089/ars.2021.0091] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 02/06/2023]
Abstract
Significance: The small, multicopy mitochondrial genome (mitochondrial DNA [mtDNA]) is essential for efficient energy production, as alterations in its coding information or a decrease in its copy number disrupt mitochondrial ATP synthesis. However, the mitochondrial replication machinery encounters numerous challenges that may limit its ability to duplicate this important genome and that jeopardize mtDNA stability, including various lesions in the DNA template, topological stress, and an insufficient nucleotide supply. Recent Advances: An ever-growing array of DNA repair or maintenance factors are being reported to localize to the mitochondria. We review current knowledge regarding the mitochondrial factors that may contribute to the tolerance or repair of various types of changes in the mitochondrial genome, such as base damage, incorporated ribonucleotides, and strand breaks. We also discuss the newly discovered link between mtDNA instability and activation of the innate immune response. Critical Issues: By which mechanisms do mitochondria respond to challenges that threaten mtDNA maintenance? What types of mtDNA damage are repaired, and when are the affected molecules degraded instead? And, finally, which forms of mtDNA instability trigger an immune response, and how? Future Directions: Further work is required to understand the contribution of the DNA repair and damage-tolerance factors present in the mitochondrial compartment, as well as the balance between mtDNA repair and degradation. Finally, efforts to understand the events underlying mtDNA release into the cytosol are warranted. Pursuing these and many related avenues can improve our understanding of what goes wrong in mitochondrial disease. Antioxid. Redox Signal. 36, 885-905.
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Affiliation(s)
- Gustavo Carvalho
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Bruno Marçal Repolês
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Isabela Mendes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Paulina H. Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
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24
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Pommier Y, Nussenzweig A, Takeda S, Austin C. Human topoisomerases and their roles in genome stability and organization. Nat Rev Mol Cell Biol 2022; 23:407-427. [PMID: 35228717 PMCID: PMC8883456 DOI: 10.1038/s41580-022-00452-3] [Citation(s) in RCA: 226] [Impact Index Per Article: 75.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
Human topoisomerases comprise a family of six enzymes: two type IB (TOP1 and mitochondrial TOP1 (TOP1MT), two type IIA (TOP2A and TOP2B) and two type IA (TOP3A and TOP3B) topoisomerases. In this Review, we discuss their biochemistry and their roles in transcription, DNA replication and chromatin remodelling, and highlight the recent progress made in understanding TOP3A and TOP3B. Because of recent advances in elucidating the high-order organization of the genome through chromatin loops and topologically associating domains (TADs), we integrate the functions of topoisomerases with genome organization. We also discuss the physiological and pathological formation of irreversible topoisomerase cleavage complexes (TOPccs) as they generate topoisomerase DNA–protein crosslinks (TOP-DPCs) coupled with DNA breaks. We discuss the expanding number of redundant pathways that repair TOP-DPCs, and the defects in those pathways, which are increasingly recognized as source of genomic damage leading to neurological diseases and cancer. Topoisomerases have essential roles in transcription, DNA replication, chromatin remodelling and, as recently revealed, 3D genome organization. However, topoisomerases also generate DNA–protein crosslinks coupled with DNA breaks, which are increasingly recognized as a source of disease-causing genomic damage.
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25
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Williams JS, Kunkel TA. Ribonucleotide Incorporation by Eukaryotic B-family Replicases and Its Implications for Genome Stability. Annu Rev Biochem 2022; 91:133-155. [PMID: 35287470 DOI: 10.1146/annurev-biochem-032620-110354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our current view of how DNA-based genomes are efficiently and accurately replicated continues to evolve as new details emerge on the presence of ribonucleotides in DNA. Ribonucleotides are incorporated during eukaryotic DNA replication at rates that make them the most common noncanonical nucleotide placed into the nuclear genome, they are efficiently repaired, and their removal impacts genome integrity. This review focuses on three aspects of this subject: the incorporation of ribonucleotides into the eukaryotic nuclear genome during replication by B-family DNA replicases, how these ribonucleotides are removed, and the consequences of their presence or removal for genome stability and disease. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Jessica S Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA;
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA;
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26
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Reijns MAM, Parry DA, Williams TC, Nadeu F, Hindshaw RL, Rios Szwed DO, Nicholson MD, Carroll P, Boyle S, Royo R, Cornish AJ, Xiang H, Ridout K, Schuh A, Aden K, Palles C, Campo E, Stankovic T, Taylor MS, Jackson AP. Signatures of TOP1 transcription-associated mutagenesis in cancer and germline. Nature 2022; 602:623-631. [PMID: 35140396 PMCID: PMC8866115 DOI: 10.1038/s41586-022-04403-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 01/04/2022] [Indexed: 12/24/2022]
Abstract
The mutational landscape is shaped by many processes. Genic regions are vulnerable to mutation but are preferentially protected by transcription-coupled repair1. In microorganisms, transcription has been demonstrated to be mutagenic2,3; however, the impact of transcription-associated mutagenesis remains to be established in higher eukaryotes4. Here we show that ID4-a cancer insertion-deletion (indel) mutation signature of unknown aetiology5 characterized by short (2 to 5 base pair) deletions -is due to a transcription-associated mutagenesis process. We demonstrate that defective ribonucleotide excision repair in mammals is associated with the ID4 signature, with mutations occurring at a TNT sequence motif, implicating topoisomerase 1 (TOP1) activity at sites of genome-embedded ribonucleotides as a mechanistic basis. Such TOP1-mediated deletions occur somatically in cancer, and the ID-TOP1 signature is also found in physiological settings, contributing to genic de novo indel mutations in the germline. Thus, although topoisomerases protect against genome instability by relieving topological stress6, their activity may also be an important source of mutations in the human genome.
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Affiliation(s)
- Martin A M Reijns
- Disease Mechanisms, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK.
| | - David A Parry
- Disease Mechanisms, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Thomas C Williams
- Disease Mechanisms, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
- Biomedical Genomics, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Ferran Nadeu
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain
| | - Rebecca L Hindshaw
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Diana O Rios Szwed
- Disease Mechanisms, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Michael D Nicholson
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Paula Carroll
- Disease Mechanisms, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Shelagh Boyle
- Genome Regulation, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK
| | - Romina Royo
- Barcelona Supercomputing Center (BSC), Barcelona, Spain
| | | | - Hang Xiang
- Institute of Clinical Molecular Biology, Christian-Albrechts-University and University Hospital Schleswig-Holstein, Kiel, Germany
| | - Kate Ridout
- Department of Oncology, University of Oxford, Oxford, UK
| | - Anna Schuh
- Department of Oncology, University of Oxford, Oxford, UK
| | - Konrad Aden
- Institute of Clinical Molecular Biology, Christian-Albrechts-University and University Hospital Schleswig-Holstein, Kiel, Germany
| | - Claire Palles
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Elias Campo
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Madrid, Spain
- Hospital Clínic of Barcelona, Barcelona, Spain
- Departament de Fonaments Clínics, Universitat de Barcelona, Barcelona, Spain
| | - Tatjana Stankovic
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Martin S Taylor
- Biomedical Genomics, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK.
| | - Andrew P Jackson
- Disease Mechanisms, MRC Human Genetics Unit, Institute of Genetics and Cancer, The University of Edinburgh, Edinburgh, UK.
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27
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Singh M, Posse V, Peter B, Falkenberg M, Gustafsson C. Ribonucleotides embedded in template DNA impair mitochondrial RNA polymerase progression. Nucleic Acids Res 2022; 50:989-999. [PMID: 35018464 PMCID: PMC8789056 DOI: 10.1093/nar/gkab1251] [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: 04/23/2021] [Revised: 11/30/2021] [Accepted: 12/07/2021] [Indexed: 11/12/2022] Open
Abstract
Human mitochondria lack ribonucleotide excision repair pathways, causing misincorporated ribonucleotides (rNMPs) to remain embedded in the mitochondrial genome. Previous studies have demonstrated that human mitochondrial DNA polymerase γ can bypass a single rNMP, but that longer stretches of rNMPs present an obstacle to mitochondrial DNA replication. Whether embedded rNMPs also affect mitochondrial transcription has not been addressed. Here we demonstrate that mitochondrial RNA polymerase elongation activity is affected by a single, embedded rNMP in the template strand. The effect is aggravated at stretches with two or more consecutive rNMPs in a row and cannot be overcome by addition of the mitochondrial transcription elongation factor TEFM. Our findings lead us to suggest that impaired transcription may be of functional relevance in genetic disorders associated with imbalanced nucleotide pools and higher levels of embedded rNMPs.
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Affiliation(s)
- Meenakshi Singh
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Viktor Posse
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
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28
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Nickoloff JA, Sharma N, Taylor L, Allen SJ, Hromas R. The Safe Path at the Fork: Ensuring Replication-Associated DNA Double-Strand Breaks are Repaired by Homologous Recombination. Front Genet 2021; 12:748033. [PMID: 34646312 PMCID: PMC8502867 DOI: 10.3389/fgene.2021.748033] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 09/14/2021] [Indexed: 01/15/2023] Open
Abstract
Cells must replicate and segregate their DNA to daughter cells accurately to maintain genome stability and prevent cancer. DNA replication is usually fast and accurate, with intrinsic (proofreading) and extrinsic (mismatch repair) error-correction systems. However, replication forks slow or stop when they encounter DNA lesions, natural pause sites, and difficult-to-replicate sequences, or when cells are treated with DNA polymerase inhibitors or hydroxyurea, which depletes nucleotide pools. These challenges are termed replication stress, to which cells respond by activating DNA damage response signaling pathways that delay cell cycle progression, stimulate repair and replication fork restart, or induce apoptosis. Stressed forks are managed by rescue from adjacent forks, repriming, translesion synthesis, template switching, and fork reversal which produces a single-ended double-strand break (seDSB). Stressed forks also collapse to seDSBs when they encounter single-strand nicks or are cleaved by structure-specific nucleases. Reversed and cleaved forks can be restarted by homologous recombination (HR), but seDSBs pose risks of mis-rejoining by non-homologous end-joining (NHEJ) to other DSBs, causing genome rearrangements. HR requires resection of broken ends to create 3' single-stranded DNA for RAD51 recombinase loading, and resected ends are refractory to repair by NHEJ. This Mini Review highlights mechanisms that help maintain genome stability by promoting resection of seDSBs and accurate fork restart by HR.
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Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO, United States
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO, United States
| | - Lynn Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO, United States
| | - Sage J Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO, United States
| | - Robert Hromas
- Division of Hematology and Medical Oncology, Department of Medicine and the Mays Cancer Center, University of Texas Health Science Center, San Antonio, TX, United States
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29
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St Germain C, Zhao H, Barlow JH. Transcription-Replication Collisions-A Series of Unfortunate Events. Biomolecules 2021; 11:1249. [PMID: 34439915 PMCID: PMC8391903 DOI: 10.3390/biom11081249] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/12/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Transcription-replication interactions occur when DNA replication encounters genomic regions undergoing transcription. Both replication and transcription are essential for life and use the same DNA template making conflicts unavoidable. R-loops, DNA supercoiling, DNA secondary structure, and chromatin-binding proteins are all potential obstacles for processive replication or transcription and pose an even more potent threat to genome integrity when these processes co-occur. It is critical to maintaining high fidelity and processivity of transcription and replication while navigating through a complex chromatin environment, highlighting the importance of defining cellular pathways regulating transcription-replication interaction formation, evasion, and resolution. Here we discuss how transcription influences replication fork stability, and the safeguards that have evolved to navigate transcription-replication interactions and maintain genome integrity in mammalian cells.
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Affiliation(s)
- Commodore St Germain
- School of Mathematics and Science, Solano Community College, 4000 Suisun Valley Road, Fairfield, CA 94534, USA
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
| | - Hongchang Zhao
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
| | - Jacqueline H. Barlow
- Department of Microbiology and Molecular Genetics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA;
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30
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Yin L, Zhu Z, Huang L, Luo X, Li Y, Xiao C, Yang J, Wang J, Zou Q, Tao L, Kang Z, Tang R, Wang M, Fu S. DNA repair- and nucleotide metabolism-related genes exhibit differential CHG methylation patterns in natural and synthetic polyploids (Brassica napus L.). HORTICULTURE RESEARCH 2021; 8:142. [PMID: 34193846 PMCID: PMC8245426 DOI: 10.1038/s41438-021-00576-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/29/2021] [Accepted: 04/07/2021] [Indexed: 05/03/2023]
Abstract
Polyploidization plays a crucial role in the evolution of angiosperm species. Almost all newly formed polyploids encounter genetic or epigenetic instabilities. However, the molecular mechanisms contributing to genomic instability in synthetic polyploids have not been clearly elucidated. Here, we performed a comprehensive transcriptomic and methylomic analysis of natural and synthetic polyploid rapeseeds (Brassica napus). Our results showed that the CHG methylation levels of synthetic rapeseed in different genomic contexts (genes, transposon regions, and repeat regions) were significantly lower than those of natural rapeseed. The total number and length of CHG-DMRs between natural and synthetic polyploids were much greater than those of CG-DMRs and CHH-DMRs, and the genes overlapping with these CHG-DMRs were significantly enriched in DNA damage repair and nucleotide metabolism pathways. These results indicated that CHG methylation may be more sensitive than CG and CHH methylation in regulating the stability of the polyploid genome of B. napus. In addition, many genes involved in DNA damage repair, nucleotide metabolism, and cell cycle control were significantly differentially expressed between natural and synthetic rapeseeds. Our results highlight that the genes related to DNA repair and nucleotide metabolism display differential CHG methylation patterns between natural and synthetic polyploids and reveal the potential connection between the genomic instability of polyploid plants with DNA methylation defects and dysregulation of the DNA repair system. In addition, it was found that the maintenance of CHG methylation in B. napus might be partially regulated by MET1. Our study provides novel insights into the establishment and evolution of polyploid plants and offers a potential idea for improving the genomic stability of newly formed Brassica polyploids.
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Affiliation(s)
- Liqin Yin
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China.
- College of Life Sciences, Sichuan University, 29 Wangjiang Road, Chengdu, China.
| | - Zhendong Zhu
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Liangjun Huang
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
- Agricultural College, Sichuan Agricultural University, 211 Huimin Road, Chengdu, China
| | - Xuan Luo
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
- Agricultural College, Sichuan Agricultural University, 211 Huimin Road, Chengdu, China
| | - Yun Li
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Chaowen Xiao
- College of Life Sciences, Sichuan University, 29 Wangjiang Road, Chengdu, China
| | - Jin Yang
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Jisheng Wang
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Qiong Zou
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Lanrong Tao
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Zeming Kang
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Rong Tang
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China
| | - Maolin Wang
- College of Life Sciences, Sichuan University, 29 Wangjiang Road, Chengdu, China.
| | - Shaohong Fu
- Institute of Crop Research, Chengdu Academy of Agricultural and Forestry Sciences, 200 Nongke Road, Chengdu, China.
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31
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Ashour ME, Mosammaparast N. Mechanisms of damage tolerance and repair during DNA replication. Nucleic Acids Res 2021; 49:3033-3047. [PMID: 33693881 PMCID: PMC8034635 DOI: 10.1093/nar/gkab101] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/28/2021] [Accepted: 03/02/2021] [Indexed: 01/05/2023] Open
Abstract
Accurate duplication of chromosomal DNA is essential for the transmission of genetic information. The DNA replication fork encounters template lesions, physical barriers, transcriptional machinery, and topological barriers that challenge the faithful completion of the replication process. The flexibility of replisomes coupled with tolerance and repair mechanisms counteract these replication fork obstacles. The cell possesses several universal mechanisms that may be activated in response to various replication fork impediments, but it has also evolved ways to counter specific obstacles. In this review, we will discuss these general and specific strategies to counteract different forms of replication associated damage to maintain genomic stability.
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Affiliation(s)
- Mohamed Elsaid Ashour
- Department of Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Nima Mosammaparast
- Department of Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
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32
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Malfatti MC, Antoniali G, Codrich M, Burra S, Mangiapane G, Dalla E, Tell G. New perspectives in cancer biology from a study of canonical and non-canonical functions of base excision repair proteins with a focus on early steps. Mutagenesis 2021; 35:129-149. [PMID: 31858150 DOI: 10.1093/mutage/gez051] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 12/05/2019] [Indexed: 12/15/2022] Open
Abstract
Alterations of DNA repair enzymes and consequential triggering of aberrant DNA damage response (DDR) pathways are thought to play a pivotal role in genomic instabilities associated with cancer development, and are further thought to be important predictive biomarkers for therapy using the synthetic lethality paradigm. However, novel unpredicted perspectives are emerging from the identification of several non-canonical roles of DNA repair enzymes, particularly in gene expression regulation, by different molecular mechanisms, such as (i) non-coding RNA regulation of tumour suppressors, (ii) epigenetic and transcriptional regulation of genes involved in genotoxic responses and (iii) paracrine effects of secreted DNA repair enzymes triggering the cell senescence phenotype. The base excision repair (BER) pathway, canonically involved in the repair of non-distorting DNA lesions generated by oxidative stress, ionising radiation, alkylation damage and spontaneous or enzymatic deamination of nucleotide bases, represents a paradigm for the multifaceted roles of complex DDR in human cells. This review will focus on what is known about the canonical and non-canonical functions of BER enzymes related to cancer development, highlighting novel opportunities to understand the biology of cancer and representing future perspectives for designing new anticancer strategies. We will specifically focus on APE1 as an example of a pleiotropic and multifunctional BER protein.
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Affiliation(s)
- Matilde Clarissa Malfatti
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
| | - Giulia Antoniali
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
| | - Marta Codrich
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
| | - Silvia Burra
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
| | - Giovanna Mangiapane
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
| | - Emiliano Dalla
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
| | - Gianluca Tell
- Laboratory of Molecular Biology and DNA repair, Department of Medicine (DAME), University of Udine, Udine, Italy
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33
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Williams JS, Tumbale PP, Arana ME, Rana JA, Williams RS, Kunkel TA. High-fidelity DNA ligation enforces accurate Okazaki fragment maturation during DNA replication. Nat Commun 2021; 12:482. [PMID: 33473124 PMCID: PMC7817679 DOI: 10.1038/s41467-020-20800-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/08/2020] [Indexed: 01/29/2023] Open
Abstract
DNA ligase 1 (LIG1, Cdc9 in yeast) finalizes eukaryotic nuclear DNA replication by sealing Okazaki fragments using DNA end-joining reactions that strongly discriminate against incorrectly paired DNA substrates. Whether intrinsic ligation fidelity contributes to the accuracy of replication of the nuclear genome is unknown. Here, we show that an engineered low-fidelity LIG1Cdc9 variant confers a novel mutator phenotype in yeast typified by the accumulation of single base insertion mutations in homonucleotide runs. The rate at which these additions are generated increases upon concomitant inactivation of DNA mismatch repair, or by inactivation of the Fen1Rad27 Okazaki fragment maturation (OFM) nuclease. Biochemical and structural data establish that LIG1Cdc9 normally avoids erroneous ligation of DNA polymerase slippage products, and this protection is compromised by mutation of a LIG1Cdc9 high-fidelity metal binding site. Collectively, our data indicate that high-fidelity DNA ligation is required to prevent insertion mutations, and that this may be particularly critical following strand displacement synthesis during the completion of OFM.
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Affiliation(s)
- Jessica S Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Percy P Tumbale
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Mercedes E Arana
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - Julian A Rana
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA
| | - R Scott Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA.
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC, 27709, USA.
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34
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Zhou ZX, Williams JS, Lujan SA, Kunkel TA. Ribonucleotide incorporation into DNA during DNA replication and its consequences. Crit Rev Biochem Mol Biol 2021; 56:109-124. [PMID: 33461360 DOI: 10.1080/10409238.2020.1869175] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ribonucleotides are the most abundant non-canonical nucleotides in the genome. Their vast presence and influence over genome biology is becoming increasingly appreciated. Here we review the recent progress made in understanding their genomic presence, incorporation characteristics and usefulness as biomarkers for polymerase enzymology. We also discuss ribonucleotide processing, the genetic consequences of unrepaired ribonucleotides in DNA and evidence supporting the significance of their transient presence in the nuclear genome.
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Affiliation(s)
- Zhi-Xiong Zhou
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
| | - Jessica S Williams
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
| | - Scott A Lujan
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
| | - Thomas A Kunkel
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
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Cerritelli SM, El Hage A. RNases H1 and H2: guardians of the stability of the nuclear genome when supply of dNTPs is limiting for DNA synthesis. Curr Genet 2020; 66:1073-1084. [PMID: 32886170 DOI: 10.1007/s00294-020-01086-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/30/2020] [Accepted: 06/01/2020] [Indexed: 11/29/2022]
Abstract
RNA/DNA hybrids are processed by RNases H1 and H2, while single ribonucleoside-monophosphates (rNMPs) embedded in genomic DNA are removed by the error-free, RNase H2-dependent ribonucleotide excision repair (RER) pathway. In the absence of RER, however, topoisomerase 1 (Top1) can cleave single genomic rNMPs in a mutagenic manner. In RNase H2-deficient mice, the accumulation of genomic rNMPs above a threshold of tolerance leads to catastrophic genomic instability that causes embryonic lethality. In humans, deficiencies in RNase H2 induce the autoimmune disorders Aicardi-Goutières syndrome and systemic lupus erythematosus, and cause skin and intestinal cancers. Recently, we reported that in Saccharomyces cerevisiae, the depletion of Rnr1, the major catalytic subunit of ribonucleotide reductase (RNR), which converts ribonucleotides to deoxyribonucleotides, leads to cell lethality in absence of RNases H1 and H2. We hypothesized that under replicative stress and compromised DNA repair that are elicited by an insufficient supply of deoxyribonucleoside-triphosphates (dNTPs), cells cannot survive the accumulation of persistent RNA/DNA hybrids. Remarkably, we found that cells lacking RNase H2 accumulate ~ 5-fold more genomic rNMPs in absence than in presence of Rnr1. When the load of genomic rNMPs is further increased in the presence of a replicative DNA polymerase variant that over-incorporates rNMPs in leading or lagging strand, cells missing both Rnr1 and RNase H2 suffer from severe growth defects. These are reversed in absence of Top1. Thus, in cells lacking RNase H2 and containing a limiting supply of dNTPs, there is a threshold of tolerance for the accumulation of genomic ribonucleotides that is tightly associated with Top1-mediated DNA damage. In this mini-review, we describe the implications of the loss of RNase H2, or RNases H1 and H2, on the integrity of the nuclear genome and viability of budding yeast cells that are challenged with a critically low supply of dNTPs. We further propose that our findings in budding yeast could pave the way for the study of the potential role of mammalian RNR in RNase H2-related diseases.
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Affiliation(s)
- Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Aziz El Hage
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
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Cerritelli SM, Iranzo J, Sharma S, Chabes A, Crouch RJ, Tollervey D, El Hage A. High density of unrepaired genomic ribonucleotides leads to Topoisomerase 1-mediated severe growth defects in absence of ribonucleotide reductase. Nucleic Acids Res 2020; 48:4274-4297. [PMID: 32187369 PMCID: PMC7192613 DOI: 10.1093/nar/gkaa103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/12/2022] Open
Abstract
Cellular levels of ribonucleoside triphosphates (rNTPs) are much higher than those of deoxyribonucleoside triphosphates (dNTPs), thereby influencing the frequency of incorporation of ribonucleoside monophosphates (rNMPs) by DNA polymerases (Pol) into DNA. RNase H2-initiated ribonucleotide excision repair (RER) efficiently removes single rNMPs in genomic DNA. However, processing of rNMPs by Topoisomerase 1 (Top1) in absence of RER induces mutations and genome instability. Here, we greatly increased the abundance of genomic rNMPs in Saccharomyces cerevisiae by depleting Rnr1, the major subunit of ribonucleotide reductase, which converts ribonucleotides to deoxyribonucleotides. We found that in strains that are depleted of Rnr1, RER-deficient, and harbor an rNTP-permissive replicative Pol mutant, excessive accumulation of single genomic rNMPs severely compromised growth, but this was reversed in absence of Top1. Thus, under Rnr1 depletion, limited dNTP pools slow DNA synthesis by replicative Pols and provoke the incorporation of high levels of rNMPs in genomic DNA. If a threshold of single genomic rNMPs is exceeded in absence of RER and presence of limited dNTP pools, Top1-mediated genome instability leads to severe growth defects. Finally, we provide evidence showing that accumulation of RNA/DNA hybrids in absence of RNase H1 and RNase H2 leads to cell lethality under Rnr1 depletion.
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Affiliation(s)
- Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Jaime Iranzo
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE-901 87, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE-901 87, Sweden
| | - Robert J Crouch
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - David Tollervey
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Aziz El Hage
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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Chromatin Architectural Factors as Safeguards against Excessive Supercoiling during DNA Replication. Int J Mol Sci 2020; 21:ijms21124504. [PMID: 32599919 PMCID: PMC7349988 DOI: 10.3390/ijms21124504] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 12/21/2022] Open
Abstract
Key DNA transactions, such as genome replication and transcription, rely on the speedy translocation of specialized protein complexes along a double-stranded, right-handed helical template. Physical tethering of these molecular machines during translocation, in conjunction with their internal architectural features, generates DNA topological strain in the form of template supercoiling. It is known that the build-up of transient excessive supercoiling poses severe threats to genome function and stability and that highly specialized enzymes—the topoisomerases (TOP)—have evolved to mitigate these threats. Furthermore, due to their intracellular abundance and fast supercoil relaxation rates, it is generally assumed that these enzymes are sufficient in coping with genome-wide bursts of excessive supercoiling. However, the recent discoveries of chromatin architectural factors that play important accessory functions have cast reasonable doubts on this concept. Here, we reviewed the background of these new findings and described emerging models of how these accessory factors contribute to supercoil homeostasis. We focused on DNA replication and the generation of positive (+) supercoiling in front of replisomes, where two accessory factors—GapR and HMGA2—from pro- and eukaryotic cells, respectively, appear to play important roles as sinks for excessive (+) supercoiling by employing a combination of supercoil constrainment and activation of topoisomerases. Looking forward, we expect that additional factors will be identified in the future as part of an expanding cellular repertoire to cope with bursts of topological strain. Furthermore, identifying antagonists that target these accessory factors and work synergistically with clinically relevant topoisomerase inhibitors could become an interesting novel strategy, leading to improved treatment outcomes.
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Saha LK, Wakasugi M, Akter S, Prasad R, Wilson SH, Shimizu N, Sasanuma H, Huang SYN, Agama K, Pommier Y, Matsunaga T, Hirota K, Iwai S, Nakazawa Y, Ogi T, Takeda S. Topoisomerase I-driven repair of UV-induced damage in NER-deficient cells. Proc Natl Acad Sci U S A 2020; 117:14412-14420. [PMID: 32513688 PMCID: PMC7321995 DOI: 10.1073/pnas.1920165117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Nucleotide excision repair (NER) removes helix-destabilizing adducts including ultraviolet (UV) lesions, cyclobutane pyrimidine dimers (CPDs), and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs). In comparison with CPDs, 6-4PPs have greater cytotoxicity and more strongly destabilizing properties of the DNA helix. It is generally believed that NER is the only DNA repair pathway that removes the UV lesions as evidenced by the previous data since no repair of UV lesions was detected in NER-deficient skin fibroblasts. Topoisomerase I (TOP1) constantly creates transient single-strand breaks (SSBs) releasing the torsional stress in genomic duplex DNA. Stalled TOP1-SSB complexes can form near DNA lesions including abasic sites and ribonucleotides embedded in chromosomal DNA. Here we show that base excision repair (BER) increases cellular tolerance to UV independently of NER in cancer cells. UV lesions irreversibly trap stable TOP1-SSB complexes near the UV damage in NER-deficient cells, and the resulting SSBs activate BER. Biochemical experiments show that 6-4PPs efficiently induce stable TOP1-SSB complexes, and the long-patch repair synthesis of BER removes 6-4PPs downstream of the SSB. Furthermore, NER-deficient cancer cell lines remove 6-4PPs within 24 h, but not CPDs, and the removal correlates with TOP1 expression. NER-deficient skin fibroblasts weakly express TOP1 and show no detectable repair of 6-4PPs. Remarkably, the ectopic expression of TOP1 in these fibroblasts led them to completely repair 6-4PPs within 24 h. In conclusion, we reveal a DNA repair pathway initiated by TOP1, which significantly contributes to cellular tolerance to UV-induced lesions particularly in malignant cancer cells overexpressing TOP1.
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Affiliation(s)
- Liton Kumar Saha
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, 606-8501 Kyoto, Japan
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Mitsuo Wakasugi
- Laboratory of Human Molecular Genetics, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 920-1192 Kanazawa, Japan
| | - Salma Akter
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, 606-8501 Kyoto, Japan
| | - Rajendra Prasad
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709
| | - Naoto Shimizu
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, 606-8501 Kyoto, Japan
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, 606-8501 Kyoto, Japan
| | - Shar-Yin Naomi Huang
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Keli Agama
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892
| | - Tsukasa Matsunaga
- Laboratory of Human Molecular Genetics, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 920-1192 Kanazawa, Japan
| | - Kouji Hirota
- Department of Chemistry, Tokyo Metropolitan University, 192-0397 Tokyo, Japan
| | - Shigenori Iwai
- Biological Chemistry Group, Graduate School of Engineering Science, Osaka University, 565-0871 Osaka, Japan
| | - Yuka Nakazawa
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, 464-8601 Nagoya, Japan
| | - Tomoo Ogi
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, 464-8601 Nagoya, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Kyoto University, Graduate School of Medicine, 606-8501 Kyoto, Japan;
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Álvarez-Quilón A, Wojtaszek JL, Mathieu MC, Patel T, Appel CD, Hustedt N, Rossi SE, Wallace BD, Setiaputra D, Adam S, Ohashi Y, Melo H, Cho T, Gervais C, Muñoz IM, Grazzini E, Young JTF, Rouse J, Zinda M, Williams RS, Durocher D. Endogenous DNA 3' Blocks Are Vulnerabilities for BRCA1 and BRCA2 Deficiency and Are Reversed by the APE2 Nuclease. Mol Cell 2020; 78:1152-1165.e8. [PMID: 32516598 PMCID: PMC7340272 DOI: 10.1016/j.molcel.2020.05.021] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/18/2020] [Accepted: 05/13/2020] [Indexed: 02/08/2023]
Abstract
The APEX2 gene encodes APE2, a nuclease related to APE1, the apurinic/apyrimidinic endonuclease acting in base excision repair. Loss of APE2 is lethal in cells with mutated BRCA1 or BRCA2, making APE2 a prime target for homologous recombination-defective cancers. However, because the function of APE2 in DNA repair is poorly understood, it is unclear why BRCA-deficient cells require APE2 for viability. Here we present the genetic interaction profiles of APE2, APE1, and TDP1 deficiency coupled to biochemical and structural dissection of APE2. We conclude that the main role of APE2 is to reverse blocked 3' DNA ends, problematic lesions that preclude DNA synthesis. Our work also suggests that TOP1 processing of genomic ribonucleotides is the main source of 3'-blocking lesions relevant to APEX2-BRCA1/2 synthetic lethality. The exquisite sensitivity of BRCA-deficient cells to 3' blocks indicates that they represent a tractable vulnerability in homologous recombination-deficient tumor cells.
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Affiliation(s)
- Alejandro Álvarez-Quilón
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Jessica L Wojtaszek
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, US Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Marie-Claude Mathieu
- Repare Therapeutics, 7210 Frederick-Banting, Suite 100, St-Laurent, QC H4S 2A1, Canada
| | - Tejas Patel
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, US Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | - C Denise Appel
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, US Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Nicole Hustedt
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Silvia Emma Rossi
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Bret D Wallace
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, US Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Dheva Setiaputra
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Salomé Adam
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Yota Ohashi
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Henrique Melo
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada
| | - Tiffany Cho
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Christian Gervais
- National Research Council Canada Human Health Therapeutics Research Center, 6100 Royalmount Avenue, Montreal, QC H4P 2R2, Canada
| | - Ivan M Muñoz
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Eric Grazzini
- National Research Council Canada Human Health Therapeutics Research Center, 6100 Royalmount Avenue, Montreal, QC H4P 2R2, Canada
| | - Jordan T F Young
- Repare Therapeutics, 7210 Frederick-Banting, Suite 100, St-Laurent, QC H4S 2A1, Canada
| | - John Rouse
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Michael Zinda
- Repare Therapeutics, 7210 Frederick-Banting, Suite 100, St-Laurent, QC H4S 2A1, Canada
| | - R Scott Williams
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, US Department of Health and Human Services, 111 TW Alexander Drive, Research Triangle Park, NC 27709, USA.
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
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40
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Nava GM, Grasso L, Sertic S, Pellicioli A, Muzi Falconi M, Lazzaro F. One, No One, and One Hundred Thousand: The Many Forms of Ribonucleotides in DNA. Int J Mol Sci 2020; 21:E1706. [PMID: 32131532 PMCID: PMC7084774 DOI: 10.3390/ijms21051706] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/26/2020] [Accepted: 02/28/2020] [Indexed: 12/14/2022] Open
Abstract
In the last decade, it has become evident that RNA is frequently found in DNA. It is now well established that single embedded ribonucleoside monophosphates (rNMPs) are primarily introduced by DNA polymerases and that longer stretches of RNA can anneal to DNA, generating RNA:DNA hybrids. Among them, the most studied are R-loops, peculiar three-stranded nucleic acid structures formed upon the re-hybridization of a transcript to its template DNA. In addition, polyribonucleotide chains are synthesized to allow DNA replication priming, double-strand breaks repair, and may as well result from the direct incorporation of consecutive rNMPs by DNA polymerases. The bright side of RNA into DNA is that it contributes to regulating different physiological functions. The dark side, however, is that persistent RNA compromises genome integrity and genome stability. For these reasons, the characterization of all these structures has been under growing investigation. In this review, we discussed the origin of single and multiple ribonucleotides in the genome and in the DNA of organelles, focusing on situations where the aberrant processing of RNA:DNA hybrids may result in multiple rNMPs embedded in DNA. We concluded by providing an overview of the currently available strategies to study the presence of single and multiple ribonucleotides in DNA in vivo.
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Affiliation(s)
| | | | | | | | - Marco Muzi Falconi
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy; (G.M.N.); (L.G.); (S.S.); (A.P.)
| | - Federico Lazzaro
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy; (G.M.N.); (L.G.); (S.S.); (A.P.)
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41
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The Functional Consequences of Eukaryotic Topoisomerase 1 Interaction with G-Quadruplex DNA. Genes (Basel) 2020; 11:genes11020193. [PMID: 32059547 PMCID: PMC7073998 DOI: 10.3390/genes11020193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/07/2020] [Accepted: 02/09/2020] [Indexed: 12/22/2022] Open
Abstract
Topoisomerase I in eukaryotic cells is an important regulator of DNA topology. Its catalytic function is to remove positive or negative superhelical tension by binding to duplex DNA, creating a reversible single-strand break, and finally religating the broken strand. Proper maintenance of DNA topological homeostasis, in turn, is critically important in the regulation of replication, transcription, DNA repair, and other processes of DNA metabolism. One of the cellular processes regulated by the DNA topology and thus by Topoisomerase I is the formation of non-canonical DNA structures. Non-canonical or non-B DNA structures, including the four-stranded G-quadruplex or G4 DNA, are potentially pathological in that they interfere with replication or transcription, forming hotspots of genome instability. In this review, we first describe the role of Topoisomerase I in reducing the formation of non-canonical nucleic acid structures in the genome. We further discuss the interesting recent discovery that Top1 and Top1 mutants bind to G4 DNA structures in vivo and in vitro and speculate on the possible consequences of these interactions.
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42
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Kellner V, Luke B. Molecular and physiological consequences of faulty eukaryotic ribonucleotide excision repair. EMBO J 2020; 39:e102309. [PMID: 31833079 PMCID: PMC6996501 DOI: 10.15252/embj.2019102309] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/22/2019] [Accepted: 11/26/2019] [Indexed: 01/11/2023] Open
Abstract
The duplication of the eukaryotic genome is an intricate process that has to be tightly safe-guarded. One of the most frequently occurring errors during DNA synthesis is the mis-insertion of a ribonucleotide instead of a deoxyribonucleotide. Ribonucleotide excision repair (RER) is initiated by RNase H2 and results in error-free removal of such mis-incorporated ribonucleotides. If left unrepaired, DNA-embedded ribonucleotides result in a variety of alterations within chromosomal DNA, which ultimately lead to genome instability. Here, we review how genomic ribonucleotides lead to chromosomal aberrations and discuss how the tight regulation of RER timing may be important for preventing unwanted DNA damage. We describe the structural impact of unrepaired ribonucleotides on DNA and chromatin and comment on the potential consequences for cellular fitness. In the context of the molecular mechanisms associated with faulty RER, we have placed an emphasis on how and why increased levels of genomic ribonucleotides are associated with severe autoimmune syndromes, neuropathology, and cancer. In addition, we discuss therapeutic directions that could be followed for pathologies associated with defective removal of ribonucleotides from double-stranded DNA.
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Affiliation(s)
- Vanessa Kellner
- Institute of Molecular Biology (IMB)MainzGermany
- Present address:
Department of BiologyNew York UniversityNew YorkNYUSA
| | - Brian Luke
- Institute of Molecular Biology (IMB)MainzGermany
- Institute of Developmental Biology and Neurobiology (IDN)Johannes Gutenberg UniversitätMainzGermany
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43
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Uehara R, Cerritelli SM, Hasin N, Sakhuja K, London M, Iranzo J, Chon H, Grinberg A, Crouch RJ. Two RNase H2 Mutants with Differential rNMP Processing Activity Reveal a Threshold of Ribonucleotide Tolerance for Embryonic Development. Cell Rep 2019; 25:1135-1145.e5. [PMID: 30380406 PMCID: PMC6309994 DOI: 10.1016/j.celrep.2018.10.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/18/2018] [Accepted: 10/03/2018] [Indexed: 11/30/2022] Open
Abstract
RNase H2 has two distinct functions: initiation of the ribonucleotide excision repair (RER) pathway by cleaving ribonucleotides (rNMPs) incorporated during DNA replication and processing the RNA portion of an R-loop formed during transcription. An RNase H2 mutant lacking RER activity but supporting R-loop removal revealed that rNMPs in DNA initiate p53-dependent DNA damage response and early embryonic arrest in mouse. However, an RNase H2 AGS-related mutant with residual RER activity develops to birth. Estimations of the number of rNMPs in DNA in these two mutants define a ribonucleotide threshold above which p53 induces apoptosis. Below the threshold, rNMPs in DNA trigger an innate immune response. Compound heterozygous cells, containing both defective enzymes, retain rNMPs above the threshold, indicative of competition for RER substrates between active and inactive enzymes, suggesting that patients with compound heterozygous mutations in RNASEH2 genes may not reflect the properties of recombinantly expressed proteins. Uehara et al. use RNase H2 mice with differing activity levels for removal of rNMPs embedded in DNA. Moderate levels of rNMPs lead to perinatal lethality activating the cGAS-Sting DNA sensing innate immune response. Exceeding a threshold, high abundance of rNMPs activates p53-dependent DNA damage, causing early embryonic lethality.
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Affiliation(s)
- Ryo Uehara
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Naushaba Hasin
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Kiran Sakhuja
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Mariya London
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Jaime Iranzo
- NCBI, National Library of Medicine, Bethesda, MD, USA
| | - Hyongi Chon
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Alexander Grinberg
- Mouse Core, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Robert J Crouch
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.
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44
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Cerritelli SM, Crouch RJ. RNase H2-RED carpets the path to eukaryotic RNase H2 functions. DNA Repair (Amst) 2019; 84:102736. [PMID: 31761672 PMCID: PMC6936605 DOI: 10.1016/j.dnarep.2019.102736] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 10/15/2019] [Indexed: 11/24/2022]
Abstract
Eukaryotic RNases H2 have dual functions in initiating the removal of ribonucleoside monophosphates (rNMPs) incorporated by DNA polymerases during DNA synthesis and in cleaving the RNA moiety of RNA/DNA hybrids formed during transcription and retrotransposition. The other major cellular RNase H, RNase H1, shares the hybrid processing activity, but not all substrates. After RNase H2 incision at the rNMPs in DNA the Ribonucleotide Excision Repair (RER) pathway completes the removal, restoring dsDNA. The development of the RNase H2-RED (Ribonucleotide Excision Defective) mutant enzyme, which can process RNA/DNA hybrids but is unable to cleave rNMPs embedded in DNA has unlinked the two activities and illuminated the roles of RNase H2 in cellular metabolism. Studies mostly in Saccharomyces cerevisiae, have shown both activities of RNase H2 are necessary to maintain genome integrity and that RNase H1 and H2 have overlapping as well as distinct RNA/DNA hybrid substrates. In mouse RNase H2-RED confirmed that rNMPs in DNA during embryogenesis induce lethality in a p53-dependent DNA damage response. In mammalian cell cultures, RNase H2-RED helped identifying DNA lesions produced by Top1 cleavage at rNMPs and led to determine that RNase H2 participates in the retrotransposition of LINE-1 elements. In this review, we summarize the studies and conclusions reached by utilization of RNase H2-RED enzyme in different model systems.
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Affiliation(s)
- Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Robert J Crouch
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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Lockhart A, Pires VB, Bento F, Kellner V, Luke-Glaser S, Yakoub G, Ulrich HD, Luke B. RNase H1 and H2 Are Differentially Regulated to Process RNA-DNA Hybrids. Cell Rep 2019; 29:2890-2900.e5. [DOI: 10.1016/j.celrep.2019.10.108] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/10/2019] [Accepted: 10/28/2019] [Indexed: 10/25/2022] Open
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Abstract
DNA topoisomerases are enzymes that catalyze changes in the torsional and flexural strain of DNA molecules. Earlier studies implicated these enzymes in a variety of processes in both prokaryotes and eukaryotes, including DNA replication, transcription, recombination, and chromosome segregation. Studies performed over the past 3 years have provided new insight into the roles of various topoisomerases in maintaining eukaryotic chromosome structure and facilitating the decatenation of daughter chromosomes at cell division. In addition, recent studies have demonstrated that the incorporation of ribonucleotides into DNA results in trapping of topoisomerase I (TOP1)–DNA covalent complexes during aborted ribonucleotide removal. Importantly, such trapped TOP1–DNA covalent complexes, formed either during ribonucleotide removal or as a consequence of drug action, activate several repair processes, including processes involving the recently described nuclear proteases SPARTAN and GCNA-1. A variety of new TOP1 inhibitors and formulations, including antibody–drug conjugates and PEGylated complexes, exert their anticancer effects by also trapping these TOP1–DNA covalent complexes. Here we review recent developments and identify further questions raised by these new findings.
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Affiliation(s)
- Mary-Ann Bjornsti
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, 35294-0019, USA
| | - Scott H Kaufmann
- Departments of Oncology and Molecular Pharmacolgy & Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
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Processing of a single ribonucleotide embedded into DNA by human nucleotide excision repair and DNA polymerase η. Sci Rep 2019; 9:13910. [PMID: 31558768 PMCID: PMC6763444 DOI: 10.1038/s41598-019-50421-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/05/2019] [Indexed: 12/18/2022] Open
Abstract
DNA polymerases often incorporate non-canonical nucleotide, i.e., ribonucleoside triphosphates into the genomic DNA. Aberrant accumulation of ribonucleotides in the genome causes various cellular abnormalities. Here, we show the possible role of human nucleotide excision repair (NER) and DNA polymerase η (Pol η) in processing of a single ribonucleotide embedded into DNA. We found that the reconstituted NER system can excise the oxidized ribonucleotide on the plasmid DNA. Taken together with the evidence that Pol η accurately bypasses a ribonucleotide, i.e., riboguanosine (rG) or its oxidized derivative (8-oxo-rG) in vitro, we further assessed the mutagenic potential of the embedded ribonucleotide in human cells lacking NER or Pol η. A single rG on the supF reporter gene predominantly induced large deletion mutations. An embedded 8-oxo-rG caused base substitution mutations at the 3′-neighboring base rather than large deletions in wild-type cells. The disruption of XPA, an essential factor for NER, or Pol η leads to the increased mutant frequency of 8-oxo-rG. Furthermore, the frequency of 8-oxo-rG-mediated large deletions was increased by the loss of Pol η, but not XPA. Collectively, our results suggest that base oxidation of the embedded ribonucleotide enables processing of the ribonucleotide via alternative DNA repair and damage tolerance pathways.
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Williams JS, Lujan SA, Zhou ZX, Burkholder AB, Clark AB, Fargo DC, Kunkel TA. Genome-wide mutagenesis resulting from topoisomerase 1-processing of unrepaired ribonucleotides in DNA. DNA Repair (Amst) 2019; 84:102641. [PMID: 31311768 DOI: 10.1016/j.dnarep.2019.102641] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/28/2019] [Accepted: 07/02/2019] [Indexed: 01/10/2023]
Abstract
Ribonucleotides are the most common non-canonical nucleotides incorporated into DNA during replication, and their processing leads to mutations and genome instability. Yeast mutation reporter systems demonstrate that 2-5 base pair deletions (Δ2-5bp) in repetitive DNA are a signature of unrepaired ribonucleotides, and that these events are initiated by topoisomerase 1 (Top1) cleavage. However, a detailed understanding of the frequency and locations of ribonucleotide-dependent mutational events across the genome has been lacking. Here we present the results of genome-wide mutational analysis of yeast strains deficient in Ribonucleotide Excision Repair (RER). We identified mutations that accumulated over thousands of generations in strains expressing either wild-type or variant replicase alleles (M644G Pol ε, L612M Pol δ, L868M Pol α) that confer increased ribonucleotide incorporation into DNA. Using a custom-designed mutation-calling pipeline called muver (for mutationes verificatae), we observe a number of surprising mutagenic features. This includes a 24-fold preferential elevation of AG and AC relative to AT dinucleotide deletions in the absence of RER, suggesting specificity for Top1-initiated deletion mutagenesis. Moreover, deletion rates in di- and trinucleotide repeat tracts increase exponentially with tract length. Consistent with biochemical and reporter gene mutational analysis, these deletions are no longer observed upon deletion of TOP1. Taken together, results from these analyses demonstrate the global impact of genomic ribonucleotide processing by Top1 on genome integrity.
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Affiliation(s)
- Jessica S Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - Scott A Lujan
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - Zhi-Xiong Zhou
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - Adam B Burkholder
- Integrative Bioinformatics Support Group, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - Alan B Clark
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - David C Fargo
- Integrative Bioinformatics Support Group, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC, USA.
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49
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Wanrooij PH, Chabes A. Ribonucleotides in mitochondrial DNA. FEBS Lett 2019; 593:1554-1565. [PMID: 31093968 DOI: 10.1002/1873-3468.13440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/09/2019] [Accepted: 05/09/2019] [Indexed: 01/05/2023]
Abstract
The incorporation of ribonucleotides (rNMPs) into DNA during genome replication has gained substantial attention in recent years and has been shown to be a significant source of genomic instability. Studies in yeast and mammals have shown that the two genomes, the nuclear DNA (nDNA) and the mitochondrial DNA (mtDNA), differ with regard to their rNMP content. This is largely due to differences in rNMP repair - whereas rNMPs are efficiently removed from the nuclear genome, mitochondria lack robust mechanisms for removal of single rNMPs incorporated during DNA replication. In this minireview, we describe the processes that determine the frequency of rNMPs in the mitochondrial genome and summarise recent findings regarding the effect of incorporated rNMPs on mtDNA stability and function.
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Affiliation(s)
- Paulina H Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Sweden
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Ren M, Cheng Y, Duan Q, Zhou C. Transesterification Reaction and the Repair of Embedded Ribonucleotides in DNA Are Suppressed upon the Assembly of DNA into Nucleosome Core Particles †. Chem Res Toxicol 2019; 32:926-934. [PMID: 30990021 DOI: 10.1021/acs.chemrestox.9b00059] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Ribonucleotides can be incorporated into DNA through many different cellular processes, and abundant amounts of ribonucleotides are detected in genomic DNA. Embedded ribonucleotides lead to genomic instability through either spontaneous ribonucleotide cleavage via internal transesterification or by inducing mutagenesis, recombination, and chromosome rearrangements. Ribonucleotides misincorporated in genomic DNA can be removed by the ribonucleotide excision repair (RER) pathway in which RNase HII initiates the repair by cleaving the 5'-phosphate of the ribonucleotide. Herein, based on in vitro reconstituted nucleosome core particles (NCPs) containing a single ribonucleotide at different positions, we studied the kinetics of ribonucleotide cleavage via the internal transesterification reaction and repair of the ribonucleotides by RNase HII in NCPs. Our results show that ribonucleotide cleavage via the internal transesterification in NCPs is suppressed compared to that in free DNA. DNA bending and structural rigidity account for the suppressed ribonucleotide cleavage in NCPs. Ribonucleotide repair by RNase HII in NCPs exhibits a strong correlation between the translational and rotational positions of the ribonucleotides. An embedded ribonucleotide located at the entry site while facing outward in NCP is repaired as efficiently as that in free DNA. However, the repair of those located in the central part of NCPs and facing inward are inhibited by up to 273-fold relative to those in free dsDNA. The difference in repair efficiency appears to arise from their different accessibility to repair enzymes in NCPs. This study reveals that a ribonucleotide misincorporated in DNA assembled into NCPs is protected against cleavage. Hence, the spontaneous cleavage of the misincorporated ribonucleotides under physiological conditions is not an essential threat to the stability of chromatin DNA. Instead, their decreased repair efficiency in NCPs may result in numerous and persistent ribonucleotides in genomic DNA, which could exert other deleterious effects on DNA such as mutagenesis and recombination.
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Affiliation(s)
- Mengtian Ren
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Yiran Cheng
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Qian Duan
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, College of Chemistry , Nankai University , Tianjin 300071 , China
| | - Chuanzheng Zhou
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, College of Chemistry , Nankai University , Tianjin 300071 , China
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