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Clairmont CS, D'Andrea AD. REV7 directs DNA repair pathway choice. Trends Cell Biol 2021; 31:965-978. [PMID: 34147298 DOI: 10.1016/j.tcb.2021.05.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/18/2021] [Accepted: 05/25/2021] [Indexed: 10/21/2022]
Abstract
REV7 is a small multifunctional protein that participates in multiple DNA repair pathways, most notably translesion DNA synthesis and double-strand break (DSB) repair. While the role of REV7 in translesion synthesis has been known for several decades, its function in DSB repair is a recent discovery. Investigations into the DSB repair function of REV7 have led to the discovery of a new DNA repair complex known as Shieldin. Recent studies have also highlighted the importance of REV7's HORMA domain, an ancient structural motif, in REV7 function and have identified the HORMA regulators, TRIP13 and p31, as novel DNA repair factors. In this review, we discuss these recent findings and their implications for repair pathway choice, at both DSBs and replication forks. We suggest that REV7, in particular the activation state of its HORMA domain, can act as a critical determinant of mutagenic versus error-free repair in multiple contexts.
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Affiliation(s)
- Connor S Clairmont
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Center for DNA Damage and Repair, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
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2
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Lou J, Yang Y, Gu Q, Price BA, Qiu Y, Fedoriw Y, Desai S, Mose LE, Chen B, Tateishi S, Parker JS, Vaziri C, Wu D. Rad18 mediates specific mutational signatures and shapes the genomic landscape of carcinogen-induced tumors in vivo. NAR Cancer 2021; 3:zcaa037. [PMID: 33447826 PMCID: PMC7787264 DOI: 10.1093/narcan/zcaa037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/01/2020] [Accepted: 12/31/2020] [Indexed: 12/16/2022] Open
Abstract
The E3 ubiquitin ligase Rad18 promotes a damage-tolerant and error-prone mode of DNA replication termed trans-lesion synthesis that is pathologically activated in cancer. However, the impact of vertebrate Rad18 on cancer genomes is not known. To determine how Rad18 affects mutagenesis in vivo, we have developed and implemented a novel computational pipeline to analyze genomes of carcinogen (7, 12-Dimethylbenz[a]anthracene, DMBA)-induced skin tumors from Rad18+/+ and Rad18- / - mice. We show that Rad18 mediates specific mutational signatures characterized by high levels of A(T)>T(A) single nucleotide variations (SNVs). In Rad18- /- tumors, an alternative mutation pattern arises, which is characterized by increased numbers of deletions >4 bp. Comparison with annotated human mutational signatures shows that COSMIC signature 22 predominates in Rad18+/+ tumors whereas Rad18- / - tumors are characterized by increased contribution of COSMIC signature 3 (a hallmark of BRCA-mutant tumors). Analysis of The Cancer Genome Atlas shows that RAD18 expression is strongly associated with high SNV burdens, suggesting RAD18 also promotes mutagenesis in human cancers. Taken together, our results show Rad18 promotes mutagenesis in vivo, modulates DNA repair pathway choice in neoplastic cells, and mediates specific mutational signatures that are present in human tumors.
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Affiliation(s)
- Jitong Lou
- Department of Biostatistics, University of North Carolina at Chapel Hill, 135 Dauer Drive, 3101 McGavran-Greenberg Hall, Chapel Hill, NC 27599, USA
| | - Yang Yang
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
| | - Qisheng Gu
- Division of Oral and Craniofacial Health Sciences, Adam School of Dentistry, University of North Carolina at Chapel Hill, 385 S. Columbia Street, Chapel Hill, NC 27599, USA
| | - Brandon A Price
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 450 West Drive, Chapel Hill, NC 27599, USA
| | - Yuheng Qiu
- Department of Statistics, Purdue University, 250 N. University St, West Lafayette, IN 47907, USA
| | - Yuri Fedoriw
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
| | - Siddhi Desai
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
| | - Lisle E Mose
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 450 West Drive, Chapel Hill, NC 27599, USA
| | - Brian Chen
- Department of Biostatistics, University of North Carolina at Chapel Hill, 135 Dauer Drive, 3101 McGavran-Greenberg Hall, Chapel Hill, NC 27599, USA
| | - Satoshi Tateishi
- Department of Cell Maintenance, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo Chuoku, Kumamoto 860-0811, Japan
| | - Joel S Parker
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 450 West Drive, Chapel Hill, NC 27599, USA
| | - Cyrus Vaziri
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 614 Brinkhous-Bullitt Building, Chapel Hill, NC 27599, USA
| | - Di Wu
- Department of Biostatistics, University of North Carolina at Chapel Hill, 135 Dauer Drive, 3101 McGavran-Greenberg Hall, Chapel Hill, NC 27599, USA
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3
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Gadgil RY, Romer EJ, Goodman CC, Rider SD, Damewood FJ, Barthelemy JR, Shin-Ya K, Hanenberg H, Leffak M. Replication stress at microsatellites causes DNA double-strand breaks and break-induced replication. J Biol Chem 2020; 295:15378-15397. [PMID: 32873711 DOI: 10.1074/jbc.ra120.013495] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/23/2020] [Indexed: 12/12/2022] Open
Abstract
Short tandemly repeated DNA sequences, termed microsatellites, are abundant in the human genome. These microsatellites exhibit length instability and susceptibility to DNA double-strand breaks (DSBs) due to their tendency to form stable non-B DNA structures. Replication-dependent microsatellite DSBs are linked to genome instability signatures in human developmental diseases and cancers. To probe the causes and consequences of microsatellite DSBs, we designed a dual-fluorescence reporter system to detect DSBs at expanded (CTG/CAG) n and polypurine/polypyrimidine (Pu/Py) mirror repeat structures alongside the c-myc replication origin integrated at a single ectopic chromosomal site. Restriction cleavage near the (CTG/CAG)100 microsatellite leads to homology-directed single-strand annealing between flanking AluY elements and reporter gene deletion that can be detected by flow cytometry. However, in the absence of restriction cleavage, endogenous and exogenous replication stressors induce DSBs at the (CTG/CAG)100 and Pu/Py microsatellites. DSBs map to a narrow region at the downstream edge of the (CTG)100 lagging-strand template. (CTG/CAG) n chromosome fragility is repeat length-dependent, whereas instability at the (Pu/Py) microsatellites depends on replication polarity. Strikingly, restriction-generated DSBs and replication-dependent DSBs are not repaired by the same mechanism. Knockdown of DNA damage response proteins increases (Rad18, polymerase (Pol) η, Pol κ) or decreases (Mus81) the sensitivity of the (CTG/CAG)100 microsatellites to replication stress. Replication stress and DSBs at the ectopic (CTG/CAG)100 microsatellite lead to break-induced replication and high-frequency mutagenesis at a flanking thymidine kinase gene. Our results show that non-B structure-prone microsatellites are susceptible to replication-dependent DSBs that cause genome instability.
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Affiliation(s)
- Rujuta Yashodhan Gadgil
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA
| | - Eric J Romer
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA
| | - Caitlin C Goodman
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA
| | - S Dean Rider
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA
| | - French J Damewood
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA
| | - Joanna R Barthelemy
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA
| | - Kazuo Shin-Ya
- Biomedical Information Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | - Helmut Hanenberg
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, Düsseldorf, Germany; Department of Pediatrics III, University Children's Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Michael Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA.
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Duong PTM, Bui ATN, Kim S, Park H, Seo Y, Choi B. The interaction between ubiquitin and yeast polymerase η C terminus does not require the UBZ domain. FEBS Lett 2020; 594:1726-1737. [DOI: 10.1002/1873-3468.13783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/18/2020] [Accepted: 03/20/2020] [Indexed: 12/28/2022]
Affiliation(s)
| | | | - Seong‐Ok Kim
- Department of Chemistry KAIST Daejeon Korea
- Department of Chemistry Center for Nanomaterials and Chemical Reactions Institute of Basic Science KAIST Daejeon Korea
| | | | - Yeon‐Soo Seo
- Department of Biological Sciences KAIST Daejeon Korea
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5
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Janel-Bintz R, Kuhn L, Frit P, Chicher J, Wagner J, Haracska L, Hammann P, Cordonnier AM. Proteomic Analysis of DNA Synthesis on a Structured DNA Template in Human Cellular Extracts: Interplay Between NHEJ and Replication-Associated Proteins. Proteomics 2020; 20:e1900184. [PMID: 31999075 DOI: 10.1002/pmic.201900184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 12/19/2019] [Indexed: 01/01/2023]
Abstract
It is established that short inverted repeats trigger base substitution mutagenesis in human cells. However, how the replication machinery deals with structured DNA is unknown. It has been previously reported that in human cell-free extracts, DNA primer extension using a structured single-stranded template is transiently blocked at DNA hairpins. Here, the proteomic analysis of proteins bound to the DNA template is reported and evidence that the DNA-PK complex (DNA-PKcs and the Ku heterodimer) recognizes, and is activated by, structured single-stranded DNA is provided. Hijacking the DNA-PK complex by double-stranded oligonucleotides results in a large removal of the pausing sites and an elevated DNA extension efficiency. Conversely, DNA-PKcs inhibition results in its stabilization on the template, along with other proteins acting downstream in the Non-Homologous End-Joining (NHEJ) pathway, especially the XRCC4-DNA ligase 4 complex and the cofactor PAXX. Retention of NHEJ factors to the DNA in the absence of DNA-PKcs activity correlates with additional halts of primer extension, suggesting that these proteins hinder the progression of the DNA synthesis at these sites. Overall these results raise the possibility that, upon binding to hairpins formed onto ssDNA during fork progression, the DNA-PK complex interferes with replication fork dynamics in vivo.
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Affiliation(s)
- Régine Janel-Bintz
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, CNRS, Illkirch, 67412, France
| | - Lauriane Kuhn
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Plateforme Protéomique Strasbourg - Esplanade, FR1589, 67084, Strasbourg, France
| | - Philippe Frit
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Johana Chicher
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Plateforme Protéomique Strasbourg - Esplanade, FR1589, 67084, Strasbourg, France
| | - Jérôme Wagner
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, CNRS, Illkirch, 67412, France
| | - Lajos Haracska
- Institute of Genetics, Biological Research Center, HU-6726, Szeged, Hungary
| | - Philippe Hammann
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Plateforme Protéomique Strasbourg - Esplanade, FR1589, 67084, Strasbourg, France
| | - Agnès M Cordonnier
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, CNRS, Illkirch, 67412, France
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The translesion DNA polymerases Pol ζ and Rev1 are activated independently of PCNA ubiquitination upon UV radiation in mutants of DNA polymerase δ. PLoS Genet 2017; 13:e1007119. [PMID: 29281621 PMCID: PMC5760103 DOI: 10.1371/journal.pgen.1007119] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 01/09/2018] [Accepted: 11/20/2017] [Indexed: 02/07/2023] Open
Abstract
Replicative DNA polymerases cannot insert efficiently nucleotides at sites of base lesions. This function is taken over by specialized translesion DNA synthesis (TLS) polymerases to allow DNA replication completion in the presence of DNA damage. In eukaryotes, Rad6- and Rad18-mediated PCNA ubiquitination at lysine 164 promotes recruitment of TLS polymerases, allowing cells to efficiently cope with DNA damage. However, several studies showed that TLS polymerases can be recruited also in the absence of PCNA ubiquitination. We hypothesized that the stability of the interactions between DNA polymerase δ (Pol δ) subunits and/or between Pol δ and PCNA at the primer/template junction is a crucial factor to determine the requirement of PCNA ubiquitination. To test this hypothesis, we used a structural mutant of Pol δ in which the interaction between Pol3 and Pol31 is inhibited. We found that in yeast, rad18Δ-associated UV hypersensitivity is suppressed by pol3-ct, a mutant allele of the POL3 gene that encodes the catalytic subunit of replicative Pol δ. pol3-ct suppressor effect was specifically dependent on the Rev1 and Pol ζ TLS polymerases. This result strongly suggests that TLS polymerases could rely much less on PCNA ubiquitination when Pol δ interaction with PCNA is partially compromised by mutations. In agreement with this model, we found that the pol3-FI allele suppressed rad18Δ-associated UV sensitivity as observed for pol3-ct. This POL3 allele carries mutations within a putative PCNA Interacting Peptide (PIP) motif. We then provided molecular and genetic evidence that this motif could contribute to Pol δ-PCNA interaction indirectly, although it is not a bona fide PIP. Overall, our results suggest that the primary role of PCNA ubiquitination is to allow TLS polymerases to outcompete Pol δ for PCNA access upon DNA damage. Replicative DNA polymerases have the essential role of replicating genomic DNA during the S phase of each cell cycle. DNA replication occurs smoothly and accurately if the DNA to be replicated is undamaged. Conversely, replicative DNA polymerases stall abruptly when they encounter a damaged base on their template. In this case, alternative specialized DNA polymerases are recruited to insert nucleotides at sites of base lesions. However, these translesion polymerases are not processive and they are poorly accurate. Therefore, they need to be tightly regulated. This is achieved by the covalent binding of the small ubiquitin peptide to the polymerase cofactor PCNA that subsequently triggers the recruitment of translesion polymerases at sites of DNA damage. Yet, recruitment of translesion polymerases independently of PCNA ubiquitination also has been documented, although the underlying mechanism is not known. Moreover, this observation makes more difficult to understand the exact role of PCNA ubiquitination. Here, we present strong genetic evidence in Saccharomyces cerevisiae implying that the replicative DNA polymerase δ (Pol δ) prevents the recruitment of the translesion polymerases Pol ζ and Rev1 following UV irradiation unless PCNA is ubiquitinated. Thus, the primary role of PCNA ubiquitination would be to allow translesion polymerases to outcompete Pol δ upon DNA damage. In addition, our results led us to propose that translesion polymerases could be recruited independently of PCNA ubiquitination when Pol δ association with PCNA is challenged, for instance at difficult-to-replicate loci.
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Zafar MK, Eoff RL. Translesion DNA Synthesis in Cancer: Molecular Mechanisms and Therapeutic Opportunities. Chem Res Toxicol 2017; 30:1942-1955. [PMID: 28841374 DOI: 10.1021/acs.chemrestox.7b00157] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The genomic landscape of cancer is one marred by instability, but the mechanisms that underlie these alterations are multifaceted and remain a topic of intense research. Cellular responses to DNA damage and/or replication stress can affect genome stability in tumors and influence the response of patients to therapy. In addition to direct repair, DNA damage tolerance (DDT) is an element of genomic maintenance programs that contributes to the etiology of several types of cancer. DDT mechanisms primarily act to resolve replication stress, and this can influence the effectiveness of genotoxic drugs. Translesion DNA synthesis (TLS) is an important component of DDT that facilitates direct bypass of DNA adducts and other barriers to replication. The central role of TLS in the bypass of drug-induced DNA lesions, the promotion of tumor heterogeneity, and the involvement of these enzymes in the maintenance of the cancer stem cell niche presents an opportunity to leverage inhibition of TLS as a way of improving existing therapies. In the review that follows, we summarize mechanisms of DDT, misregulation of TLS in cancer, and discuss the potential for targeting these pathways as a means of improving cancer therapies.
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Affiliation(s)
- Maroof K Zafar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
| | - Robert L Eoff
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205-7199, United States
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8
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DNA polymerases eta and kappa exchange with the polymerase delta holoenzyme to complete common fragile site synthesis. DNA Repair (Amst) 2017; 57:1-11. [PMID: 28605669 DOI: 10.1016/j.dnarep.2017.05.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/25/2017] [Accepted: 05/29/2017] [Indexed: 12/21/2022]
Abstract
Common fragile sites (CFSs) are inherently unstable genomic loci that are recurrently altered in human tumor cells. Despite their instability, CFS are ubiquitous throughout the human genome and associated with large tumor suppressor genes or oncogenes. CFSs are enriched with repetitive DNA sequences, one feature postulated to explain why these loci are inherently difficult to replicate, and sensitive to replication stress. We have shown that specialized DNA polymerases (Pols) η and κ replicate CFS-derived sequences more efficiently than the replicative Pol δ. However, we lacked an understanding of how these enzymes cooperate to ensure efficient CFS replication. Here, we designed a model of lagging strand replication with RFC loaded PCNA that allows for maximal activity of the four-subunit human Pol δ holoenzyme, Pol η, and Pol κ in polymerase mixing assays. We discovered that Pol η and κ are both able to exchange with Pol δ stalled at repetitive CFS sequences, enhancing Normalized Replication Efficiency. We used this model to test the impact of PCNA mono-ubiquitination on polymerase exchange, and found no change in polymerase cooperativity in CFS replication compared with unmodified PCNA. Finally, we modeled replication stress in vitro using aphidicolin and found that Pol δ holoenzyme synthesis was significantly inhibited in a dose-dependent manner, preventing any replication past the CFS. Importantly, Pol η and κ were still proficient in rescuing this stalled Pol δ synthesis, which may explain, in part, the CFS instability phenotype of aphidicolin-treated Pol η and Pol κ-deficient cells. In total, our data support a model wherein Pol δ stalling at CFSs allows for free exchange with a specialized polymerase that is not driven by PCNA.
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Toth A, Hegedus L, Juhasz S, Haracska L, Burkovics P. The DNA-binding box of human SPARTAN contributes to the targeting of Polη to DNA damage sites. DNA Repair (Amst) 2016; 49:33-42. [PMID: 27838458 DOI: 10.1016/j.dnarep.2016.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/25/2016] [Accepted: 10/25/2016] [Indexed: 11/16/2022]
Abstract
Inappropriate repair of UV-induced DNA damage results in human diseases such as Xeroderma pigmentosum (XP), which is associated with an extremely high risk of skin cancer. A variant form of XP is caused by the absence of Polη, which is normally able to bypass UV-induced DNA lesions in an error-free manner. However, Polη is highly error prone when replicating undamaged DNA and, thus, the regulation of the proper targeting of Polη is crucial for the prevention of mutagenesis and UV-induced cancer formation. Spartan is a novel regulator of the damage tolerance pathway, and its association with Ub-PCNA has a role in Polη targeting; however, our knowledge about its function is only rudimentary. Here, we describe a new biochemical property of purified human SPARTAN by showing that it is a DNA-binding protein. Using a DNA binding mutant, we provide in vivo evidence that DNA binding by SPARTAN regulates the targeting of Polη to damage sites after UV exposure, and this function contributes highly to its DNA-damage tolerance function.
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Affiliation(s)
- Agnes Toth
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Lili Hegedus
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Szilvia Juhasz
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Lajos Haracska
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Peter Burkovics
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
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Stability of the human polymerase δ holoenzyme and its implications in lagging strand DNA synthesis. Proc Natl Acad Sci U S A 2016; 113:E1777-86. [PMID: 26976599 DOI: 10.1073/pnas.1523653113] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In eukaryotes, DNA polymerase δ (pol δ) is responsible for replicating the lagging strand template and anchors to the proliferating cell nuclear antigen (PCNA) sliding clamp to form a holoenzyme. The stability of this complex is integral to every aspect of lagging strand replication. Most of our understanding comes from Saccharomyces cerevisae where the extreme stability of the pol δ holoenzyme ensures that every nucleobase within an Okazaki fragment is faithfully duplicated before dissociation but also necessitates an active displacement mechanism for polymerase recycling and exchange. However, the stability of the human pol δ holoenzyme is unknown. We designed unique kinetic assays to analyze the processivity and stability of the pol δ holoenzyme. Surprisingly, the results indicate that human pol δ maintains a loose association with PCNA while replicating DNA. Such behavior has profound implications on Okazaki fragment synthesis in humans as it limits the processivity of pol δ on undamaged DNA and promotes the rapid dissociation of pol δ from PCNA on stalling at a DNA lesion.
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11
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Kumar D, Saha S. HAT3-mediated acetylation of PCNA precedes PCNA monoubiquitination following exposure to UV radiation in Leishmania donovani. Nucleic Acids Res 2015; 43:5423-41. [PMID: 25948582 PMCID: PMC4477661 DOI: 10.1093/nar/gkv431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/22/2015] [Indexed: 12/17/2022] Open
Abstract
Histone modifications impact various processes. In examining histone acetyltranferase HAT3 of Leishmania donovani, we find elimination of HAT3 causes decreased cell viability due to defects in histone deposition, and aberrant cell cycle progression pattern. HAT3 associates with proliferating cell nuclear antigen (PCNA), helping load PCNA onto chromatin in proliferating cells. HAT3-nulls show heightened sensitivity to UV radiation. Following UV exposure, PCNA cycles off/on chromatin only in cells expressing HAT3. Inhibition of the ubiquitin-proteasome pathway prior to UV exposure allows accumulation of chromatin-bound PCNA, and reveals that HAT3-nulls are deficient in PCNA monoubiquitination as well as polyubiquitination. While poor monoubiquitination of PCNA may adversely affect translesion DNA synthesis-based repair processes, polyubiquitination deficiencies may result in continued retention of chromatin-bound PCNA, leading to genomic instability. On suppressing the proteasome pathway we also find that HAT3 mediates PCNA acetylation in response to UV. HAT3-mediated PCNA acetylation may serve as a flag for PCNA ubiquitination, thus aiding DNA repair. While PCNA acetylation has previously been linked to its degradation following UV exposure, this is the first report linking a HAT-mediated PCNA acetylation to PCNA monoubiquitination. These findings add a new dimension to our knowledge of the mechanisms regulating PCNA ubiquitination post-UV exposure in eukaryotes.
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Affiliation(s)
- Devanand Kumar
- Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India
| | - Swati Saha
- Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India
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12
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Ahmed-Seghir S, Pouvelle C, Despras E, Cordonnier A, Sarasin A, Kannouche PL. Aberrant C-terminal domain of polymerase η targets the functional enzyme to the proteosomal degradation pathway. DNA Repair (Amst) 2015; 29:154-65. [PMID: 25766642 DOI: 10.1016/j.dnarep.2015.02.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 02/14/2015] [Accepted: 02/16/2015] [Indexed: 12/22/2022]
Abstract
Xeroderma pigmentosum variant (XP-V) is a rare genetic disease, characterized by sunlight sensitivity and predisposition to cutaneous malignancies. XP-V is caused by a deficiency in DNA polymerase eta (Polη) that plays a pivotal role in translesion synthesis by bypassing UV-induced pyrimidine dimers. Previously we identified a new Polη variant containing two missense mutations, one mutation within the bipartite NLS (T692A) and a second mutation on the stop codon (X714W) leading to a longer protein with an extra 8 amino acids (721 instead of 713 AA). First biochemical analysis revealed that this Polη missense variant was barely detectable by western blot. As this mutant is extremely unstable and is nearly undetectable, a definitive measure of its functional deficit in cells has not been explored. Here we report the molecular and cellular characterization of this missense variant. In cell free extracts, the extra 8 amino acids in the C-terminal of Polη(721) only slightly reduce the bypass efficiency through CPD lesions. In vivo, Polη(721) accumulates in replication factories and interacts with mUb-PCNA albeit at lower level than Polη(wt). XP-V cells overexpressing Polη(721) were only slightly UV-sensitive. Altogether, our data strongly suggest that Polη(721) is functional and that the patient displays a XP-V phenotype because the mutant protein is excessively unstable. We then investigated the molecular mechanisms involved in this excessive proteolysis. We showed that Polη(721) is degraded by the proteasome in an ubiquitin-dependent manner and that this proteolysis is independent of the E3 ligases, CRL4(cdt2) and Pirh2, reported to promote Polη degradation. We then demonstrated that the extra 8 amino acids of Polη(721) do not act as a degron but rather induce a conformational change of the Polη C-terminus exposing its bipartite NLS as well as a sequence close to its UBZ to the ubiquitin/proteasome system. Interestingly we showed that the clinically approved proteasome inhibitor, Bortezomib restores the levels of Polη(721) suggesting that this might be a therapeutic approach to preventing tumor development in certain XP-V patients harboring missense mutations.
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Affiliation(s)
- Sana Ahmed-Seghir
- Université Paris-Sud, CNRS-UMR8200, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy, Villejuif, France
| | - Caroline Pouvelle
- Université Paris-Sud, CNRS-UMR8200, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy, Villejuif, France
| | - Emmanuelle Despras
- Université Paris-Sud, CNRS-UMR8200, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy, Villejuif, France
| | | | - Alain Sarasin
- Université Paris-Sud, CNRS-UMR8200, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy, Villejuif, France
| | - Patricia L Kannouche
- Université Paris-Sud, CNRS-UMR8200, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy, Villejuif, France.
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Baldeck N, Janel-Bintz R, Wagner J, Tissier A, Fuchs RP, Burkovics P, Haracska L, Despras E, Bichara M, Chatton B, Cordonnier AM. FF483-484 motif of human Polη mediates its interaction with the POLD2 subunit of Polδ and contributes to DNA damage tolerance. Nucleic Acids Res 2015; 43:2116-25. [PMID: 25662213 PMCID: PMC4344513 DOI: 10.1093/nar/gkv076] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Switching between replicative and translesion synthesis (TLS) DNA polymerases are crucial events for the completion of genomic DNA synthesis when the replication machinery encounters lesions in the DNA template. In eukaryotes, the translesional DNA polymerase η (Polη) plays a central role for accurate bypass of cyclobutane pyrimidine dimers, the predominant DNA lesions induced by ultraviolet irradiation. Polη deficiency is responsible for a variant form of the Xeroderma pigmentosum (XPV) syndrome, characterized by a predisposition to skin cancer. Here, we show that the FF483-484 amino acids in the human Polη (designated F1 motif) are necessary for the interaction of this TLS polymerase with POLD2, the B subunit of the replicative DNA polymerase δ, both in vitro and in vivo. Mutating this motif impairs Polη function in the bypass of both an N-2-acetylaminofluorene adduct and a TT-CPD lesion in cellular extracts. By complementing XPV cells with different forms of Polη, we show that the F1 motif contributes to the progression of DNA synthesis and to the cell survival after UV irradiation. We propose that the integrity of the F1 motif of Polη, necessary for the Polη/POLD2 interaction, is required for the establishment of an efficient TLS complex.
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Affiliation(s)
- Nadège Baldeck
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, Illkirch 67412, France
| | - Régine Janel-Bintz
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, Illkirch 67412, France
| | - Jérome Wagner
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, Illkirch 67412, France
| | - Agnès Tissier
- UMR-S1052, Inserm, Centre de Recherche en Cancérologie de Lyon, Lyon 69000, France
| | - Robert P Fuchs
- Cancer Research Center of Marseille (CRCM), Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7258, Marseille 13009, France
| | - Peter Burkovics
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, HU-6726 Szeged, Hungary
| | - Lajos Haracska
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, HU-6726 Szeged, Hungary
| | - Emmanuelle Despras
- Université Paris-Sud, CNRS-UMR8200, Equipe labellisée Ligue Contre le Cancer, Gustave Roussy, Villejuif, France
| | - Marc Bichara
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, Illkirch 67412, France
| | - Bruno Chatton
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, Illkirch 67412, France
| | - Agnès M Cordonnier
- Biotechnologie et Signalisation Cellulaire, Université de Strasbourg, UMR7242, Illkirch 67412, France
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14
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Han J, Liu T, Huen MSY, Hu L, Chen Z, Huang J. SIVA1 directs the E3 ubiquitin ligase RAD18 for PCNA monoubiquitination. ACTA ACUST UNITED AC 2014; 205:811-27. [PMID: 24958773 PMCID: PMC4068132 DOI: 10.1083/jcb.201311007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Translesion DNA synthesis (TLS) is a universal DNA damage tolerance mechanism conserved from yeast to mammals. A key event in the regulation of TLS is the monoubiquitination of proliferating cell nuclear antigen (PCNA). Extensive evidence indicates that the RAD6-RAD18 ubiquitin-conjugating/ligase complex specifically monoubiquitinates PCNA and regulates TLS repair. However, the mechanism by which the RAD6-RAD18 complex is targeted to PCNA has remained elusive. In this study, we used an affinity purification approach to isolate the PCNA-containing complex and have identified SIVA1 as a critical regulator of PCNA monoubiquitination. We show that SIVA1 constitutively interacts with PCNA via a highly conserved PCNA-interacting peptide motif. Knockdown of SIVA1 compromised RAD18-dependent PCNA monoubiquitination and Polη focus formation, leading to elevated ultraviolet sensitivity and mutation. Furthermore, we demonstrate that SIVA1 interacts with RAD18 and serves as a molecular bridge between RAD18 and PCNA, thus targeting the E3 ligase activity of RAD18 onto PCNA. Collectively, our results provide evidence that the RAD18 E3 ligase requires an accessory protein for binding to its substrate PCNA.
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Affiliation(s)
- Jinhua Han
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ting Liu
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Michael S Y Huen
- Department of Anatomy and Center for Cancer Research, The University of Hong Kong, Hong Kong, China Department of Anatomy and Center for Cancer Research, The University of Hong Kong, Hong Kong, China
| | - Lin Hu
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Zhiqiu Chen
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jun Huang
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China
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15
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Bergoglio V, Boyer AS, Walsh E, Naim V, Legube G, Lee MYWT, Rey L, Rosselli F, Cazaux C, Eckert KA, Hoffmann JS. DNA synthesis by Pol η promotes fragile site stability by preventing under-replicated DNA in mitosis. ACTA ACUST UNITED AC 2013; 201:395-408. [PMID: 23609533 PMCID: PMC3639397 DOI: 10.1083/jcb.201207066] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Pol η–dependent DNA synthesis at stalled replication forks during S phase suppresses chronic fragile site instability by preventing checkpoint-blind under-replicated DNA in mitosis. Human DNA polymerase η (Pol η) is best known for its role in responding to UV irradiation–induced genome damage. We have recently observed that Pol η is also required for the stability of common fragile sites (CFSs), whose rearrangements are considered a driving force of oncogenesis. Here, we explored the molecular mechanisms underlying this newly identified role. We demonstrated that Pol η accumulated at CFSs upon partial replication stress and could efficiently replicate non-B DNA sequences within CFSs. Pol η deficiency led to persistence of checkpoint-blind under-replicated CFS regions in mitosis, detectable as FANCD2-associated chromosomal sites that were transmitted to daughter cells in 53BP1-shielded nuclear bodies. Expression of a catalytically inactive mutant of Pol η increased replication fork stalling and activated the replication checkpoint. These data are consistent with the requirement of Pol η–dependent DNA synthesis during S phase at replication forks stalled in CFS regions to suppress CFS instability by preventing checkpoint-blind under-replicated DNA in mitosis.
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Affiliation(s)
- Valérie Bergoglio
- Equipe labellisée Ligue Contre le Cancer 2013, INSERM Unit 1037, ERL5294 Centre National de la Recherche Scientifique, Cancer Research Center of Toulouse, BP3028, CHU Purpan, 31024 Toulouse, France
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16
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Parsons JL, Nicolay NH, Sharma RA. Biological and therapeutic relevance of nonreplicative DNA polymerases to cancer. Antioxid Redox Signal 2013; 18:851-73. [PMID: 22794079 PMCID: PMC3557440 DOI: 10.1089/ars.2011.4203] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Apart from surgical approaches, the treatment of cancer remains largely underpinned by radiotherapy and pharmacological agents that cause damage to cellular DNA, which ultimately causes cancer cell death. DNA polymerases, which are involved in the repair of cellular DNA damage, are therefore potential targets for inhibitors for improving the efficacy of cancer therapy. They can be divided, according to their main function, into two groups, namely replicative and nonreplicative enzymes. At least 15 different DNA polymerases, including their homologs, have been discovered to date, which vary considerably in processivity and fidelity. Many of the nonreplicative (specialized) DNA polymerases replicate DNA in an error-prone fashion, and they have been shown to participate in multiple DNA damage repair and tolerance pathways, which are often aberrant in cancer cells. Alterations in DNA repair pathways involving DNA polymerases have been linked with cancer survival and with treatment response to radiotherapy or to classes of cytotoxic drugs routinely used for cancer treatment, particularly cisplatin, oxaliplatin, etoposide, and bleomycin. Indeed, there are extensive preclinical data to suggest that DNA polymerase inhibition may prove to be a useful approach for increasing the effectiveness of therapies in patients with cancer. Furthermore, specialized DNA polymerases warrant examination of their potential use as clinical biomarkers to select for particular cancer therapies, to individualize treatment for patients.
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Affiliation(s)
- Jason L Parsons
- Cancer Research UK-Medical Research Council, Oncology Department, Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, United Kingdom
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17
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Despras E, Delrieu N, Garandeau C, Ahmed-Seghir S, Kannouche PL. Regulation of the specialized DNA polymerase eta: revisiting the biological relevance of its PCNA- and ubiquitin-binding motifs. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:752-765. [PMID: 23076824 DOI: 10.1002/em.21741] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/22/2012] [Accepted: 08/23/2012] [Indexed: 06/01/2023]
Abstract
During translesion synthesis (TLS), low-fidelity polymerases of the Y-family polymerases bypass DNA damages that block the progression of conventional processive DNA polymerases, thereby allowing the completion of DNA replication. Among the TLS polymerases, DNA polymerase eta (polη) performs nucleotide incorporation past ultraviolet (UV) photoproducts and is deficient in cancer-prone xeroderma pigmentosum variant (XPV) syndrome. Upon UV irradiation, the DNA sliding clamp PCNA is monoubiquitylated on its conserved Lys-164. This event is considered to facilitate the TLS process in vivo since polη preferentially interacts with monoubiquitylated PCNA through its ubiquitin-binding domain (UBZ) as well as its PCNA interacting peptide (PIP)-box. However, recent observations questioned this model. Therefore, in this study, we re-examined the relative contribution of the regulatory UBZ and PIP domains of polη in response to UVC. We show that simultaneous invalidation of both motifs confers sensitivity to UVC, sensitization by low concentrations of caffeine, prolonged inhibition of DNA synthesis and persistent S phase checkpoint activation, all characteristic features of XPV cells. While each domain is essential for efficient accumulation of polη in replication factories, mutational inactivation of UBZ or PIP motif only confers a slight sensitivity to UVC indicating that, although informative, polη focus analysis is not a reliable tool to assess the polη's ability to function in TLS in vivo. Taken together, these data indicate that PIP and UBZ motifs are not required for recruitment but for retention of polη at sites of stalled replication forks. We propose that this is a way to ensure that a sufficient amount of the protein is available for its bypass function.
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Affiliation(s)
- Emmanuelle Despras
- Centre Nationale de la Recherche Scientifique (CNRS) UMR8200 Laboratoire Stabilité Génétique et Oncogenèse, Université Paris-Sud, Institut Gustave Roussy, Villejuif, France.
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18
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Requirement of Rad18 protein for replication through DNA lesions in mouse and human cells. Proc Natl Acad Sci U S A 2012; 109:7799-804. [PMID: 22547805 DOI: 10.1073/pnas.1204105109] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In yeast, the Rad6-Rad18 ubiquitin conjugating enzyme plays a critical role in promoting replication although DNA lesions by translesion synthesis (TLS). In striking contrast, a number of studies have indicated that TLS can occur in the absence of Rad18 in human and other mammalian cells, and also in chicken cells. In this study, we determine the role of Rad18 in TLS that occurs during replication in human and mouse cells, and show that in the absence of Rad18, replication of duplex plasmids containing a cis-syn TT dimer or a (6-4) TT photoproduct is severely inhibited in human cells and that mutagenesis resulting from TLS opposite cyclobutane pyrimidine dimers and (6-4) photoproducts formed at the TT, TC, and CC dipyrimidine sites in the chromosomal cII gene in UV-irradiated mouse cells is abolished. From these and other observations with Rad18, we conclude that the Rad6-Rad18 enzyme plays an essential role in promoting replication through DNA lesions by TLS in mammalian cells. In contrast, the dispensability of Rad18 for TLS in chicken DT40 cells would suggest that the role of the Rad6-Rad18 enzyme complex has diverged considerably between chicken and mammals, raising the possibility that TLS mechanisms differ among them.
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19
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Janel-Bintz R, Wagner J, Haracska L, Mah-Becherel MCM, Bichara M, Fuchs RP, Cordonnier AM. Evidence for a Rad18-independent frameshift mutagenesis pathway in human cell-free extracts. PLoS One 2012; 7:e36004. [PMID: 22558303 PMCID: PMC3338768 DOI: 10.1371/journal.pone.0036004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 03/29/2012] [Indexed: 12/19/2022] Open
Abstract
Bypass of replication blocks by specialized DNA polymerases is crucial for cell survival but may promote mutagenesis and genome instability. To gain insight into mutagenic sub-pathways that coexist in mammalian cells, we examined N-2-acetylaminofluorene (AAF)-induced frameshift mutagenesis by means of SV40-based shuttle vectors containing a single adduct. We found that in mammalian cells, as previously observed in E. coli, modification of the third guanine of two target sequences, 5'-GGG-3' (3G) and 5'-GGCGCC-3' (NarI site), induces –1 and –2 frameshift mutations, respectively. Using an in vitro assay for translesion synthesis, we investigated the biochemical control of these events. We showed that Pol eta, but neither Pol iota nor Pol zeta, plays a major role in the frameshift bypass of the AAF adduct located in the 3G sequence. By complementing PCNA-depleted extracts with either a wild-type or a non-ubiquitinatable form of PCNA, we found that this Pol eta-mediated pathway requires Rad18 and ubiquitination of PCNA. In contrast, when the AAF adduct is located within the NarI site, TLS is only partially dependent upon Pol eta and Rad18, unravelling the existence of alternative pathways that concurrently bypass this lesion.
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Affiliation(s)
- Régine Janel-Bintz
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, Illkirch, France
| | - Jérôme Wagner
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, Illkirch, France
| | - Lajos Haracska
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Marcia Chia Miao Mah-Becherel
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, Illkirch, France
| | - Marc Bichara
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, Illkirch, France
| | - Robert P. Fuchs
- Campus J. Aiguier, UPR3081 Genome Instability and Carcinogenesis, Marseille, France
| | - Agnès M. Cordonnier
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, Illkirch, France
- * E-mail:
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20
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Temviriyanukul P, van Hees-Stuivenberg S, Delbos F, Jacobs H, de Wind N, Jansen JG. Temporally distinct translesion synthesis pathways for ultraviolet light-induced photoproducts in the mammalian genome. DNA Repair (Amst) 2012; 11:550-8. [PMID: 22521143 DOI: 10.1016/j.dnarep.2012.03.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 03/28/2012] [Accepted: 03/28/2012] [Indexed: 10/28/2022]
Abstract
Replicative polymerases (Pols) arrest at damaged DNA nucleotides, which induces ubiquitination of the DNA sliding clamp PCNA (PCNA-Ub) and DNA damage signaling. PCNA-Ub is associated with the recruitment or activation of translesion synthesis (TLS) DNA polymerases of the Y family that can bypass the lesions, thereby rescuing replication and preventing replication fork collapse and consequent formation of double-strand DNA breaks. Here, we have used gene-targeted mouse embryonic fibroblasts to perform a comprehensive study of the in vivo roles of PCNA-Ub and of the Y family TLS Pols η, ι, κ, Rev1 and the B family TLS Polζ in TLS and in the suppression of DNA damage signaling and genome instability after exposure to UV light. Our data indicate that TLS Pols ι and κ and the N-terminal BRCT domain of Rev1, that previously was implicated in the regulation of TLS, play minor roles in TLS of DNA photoproducts. PCNA-Ub is critical for an early TLS pathway that replicates both strongly helix-distorting (6-4) pyrimidine-pyrimidone ((6-4)PP) and mildly distorting cyclobutane pyrimidine dimer (CPD) photoproducts. The role of Polη is mainly restricted to early TLS of CPD photoproducts, whereas Rev1 and, in particular, Polζ are essential for the bypass of (6-4)PP photoproducts, both early and late after exposure. Thus, structurally distinct photoproducts at the mammalian genome are bypassed by different TLS Pols in temporally different, PCNA-Ub-dependent and independent fashions.
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Affiliation(s)
- Piya Temviriyanukul
- Department of Toxicogenetics, Leiden University Medical Center-LUMC, PO Box 9600, 2300 RC Leiden, The Netherlands.
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21
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Loakes D. Nucleotides and nucleic acids; oligo- and polynucleotides. ORGANOPHOSPHORUS CHEMISTRY 2012. [DOI: 10.1039/9781849734875-00169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- David Loakes
- Medical Research Council Laboratory of Molecular Biology, Hills Road Cambridge CB2 2QH UK
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22
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Wigan M, Pinder A, Giles N, Pavey S, Burgess A, Wong S, Sturm RA, Gabrielli B. A UVR-induced G2-phase checkpoint response to ssDNA gaps produced by replication fork bypass of unrepaired lesions is defective in melanoma. J Invest Dermatol 2012; 132:1681-8. [PMID: 22402442 DOI: 10.1038/jid.2012.41] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
UVR is a major environmental risk factor for the development of melanoma. Here we describe a coupled DNA-damage tolerance (DDT) mechanism and G2-phase cell cycle checkpoint induced in response to suberythemal doses of UVR that is commonly defective in melanomas. This coupled response is triggered by a small number of UVR-induced DNA lesions incurred during G1 phase that are not repaired by nucleotide excision repair (NER). These lesions are detected during S phase, but rather than stalling replication, they trigger the DDT-dependent formation of single-stranded DNA (ssDNA) gaps. The ssDNA attracts replication protein A (RPA), which initiates ATR-Chk1 (ataxia telangiectasia and Rad3-related/checkpoint kinase 1) G2-phase checkpoint signaling, and colocalizes with components of the RAD18 and RAD51 postreplication repair pathways. We demonstrate that depletion of RAD18 delays both the resolution of RPA foci and exit from the G2-phase arrest, indicating the involvement of RAD18-dependent postreplication repair in ssDNA gap repair during G2 phase. Moreover, the presence of RAD51 and BRCA1 suggests that an error-free mechanism may also contribute to repair. Loss of the UVR-induced G2-phase checkpoint results in increased UVR signature mutations after exposure to suberythemal UVR. We propose that defects in the UVR-induced G2-phase checkpoint and repair mechanism are likely to contribute to melanoma development.
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Affiliation(s)
- Matthew Wigan
- University of Queensland Diamantina Institute, Princess Alexandra Hospital, Brisbane, Queensland, Australia
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23
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PCNA ubiquitination is important, but not essential for translesion DNA synthesis in mammalian cells. PLoS Genet 2011; 7:e1002262. [PMID: 21931560 PMCID: PMC3169526 DOI: 10.1371/journal.pgen.1002262] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/12/2011] [Indexed: 11/19/2022] Open
Abstract
Translesion DNA synthesis (TLS) is a DNA damage tolerance mechanism in which specialized low-fidelity DNA polymerases bypass replication-blocking lesions, and it is usually associated with mutagenesis. In Saccharomyces cerevisiae a key event in TLS is the monoubiquitination of PCNA, which enables recruitment of the specialized polymerases to the damaged site through their ubiquitin-binding domain. In mammals, however, there is a debate on the requirement for ubiquitinated PCNA (PCNA-Ub) in TLS. We show that UV-induced Rpa foci, indicative of single-stranded DNA (ssDNA) regions caused by UV, accumulate faster and disappear more slowly in Pcna(K164R/K164R) cells, which are resistant to PCNA ubiquitination, compared to Pcna(+/+) cells, consistent with a TLS defect. Direct analysis of TLS in these cells, using gapped plasmids with site-specific lesions, showed that TLS is strongly reduced across UV lesions and the cisplatin-induced intrastrand GG crosslink. A similar effect was obtained in cells lacking Rad18, the E3 ubiquitin ligase which monoubiquitinates PCNA. Consistently, cells lacking Usp1, the enzyme that de-ubiquitinates PCNA exhibited increased TLS across a UV lesion and the cisplatin adduct. In contrast, cells lacking the Rad5-homologs Shprh and Hltf, which polyubiquitinate PCNA, exhibited normal TLS. Knocking down the expression of the TLS genes Rev3L, PolH, or Rev1 in Pcna(K164R/K164R) mouse embryo fibroblasts caused each an increased sensitivity to UV radiation, indicating the existence of TLS pathways that are independent of PCNA-Ub. Taken together these results indicate that PCNA-Ub is required for maximal TLS. However, TLS polymerases can be recruited to damaged DNA also in the absence of PCNA-Ub, and perform TLS, albeit at a significantly lower efficiency and altered mutagenic specificity.
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24
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Lehmann AR. Ubiquitin-family modifications in the replication of DNA damage. FEBS Lett 2011; 585:2772-9. [PMID: 21704031 DOI: 10.1016/j.febslet.2011.06.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/06/2011] [Accepted: 06/07/2011] [Indexed: 10/18/2022]
Abstract
The cell uses specialised Y-family DNA polymerases or damage avoidance mechanisms to replicate past damaged sites in DNA. These processes are under complex regulatory systems, which employ different types of post-translational modification. All the Y-family polymerases have ubiquitin binding domains that bind to mono-ubiquitinated PCNA to effect the switching from replicative to Y-family polymerase. Ubiquitination and de-ubiquitination of PCNA are tightly regulated. There is also evidence for another as yet unidentified ubiquitinated protein being involved in recruitment of Y-family polymerases to chromatin. Poly-ubiquitination of PCNA stimulates damage avoidance, and, at least in yeast, PCNA is SUMOylated to prevent unwanted recombination events at the replication fork. The Y-family polymerases themselves can be ubiquitinated and, in the case of DNA polymerase η, this results in the polymerase being excluded from chromatin.
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Affiliation(s)
- Alan R Lehmann
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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25
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Göhler T, Sabbioneda S, Green CM, Lehmann AR. ATR-mediated phosphorylation of DNA polymerase η is needed for efficient recovery from UV damage. ACTA ACUST UNITED AC 2011; 192:219-27. [PMID: 21242293 PMCID: PMC3172178 DOI: 10.1083/jcb.201008076] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phosphorylation of Polη links DNA damage–induced checkpoint activation and translesion synthesis in mammalian cells. DNA polymerase η (polη) belongs to the Y-family of DNA polymerases and facilitates translesion synthesis past UV damage. We show that, after UV irradiation, polη becomes phosphorylated at Ser601 by the ataxia-telangiectasia mutated and Rad3-related (ATR) kinase. DNA damage–induced phosphorylation of polη depends on its physical interaction with Rad18 but is independent of PCNA monoubiquitination. It requires the ubiquitin-binding domain of polη but not its PCNA-interacting motif. ATR-dependent phosphorylation of polη is necessary to restore normal survival and postreplication repair after ultraviolet irradiation in xeroderma pigmentosum variant fibroblasts, and is involved in the checkpoint response to UV damage. Taken together, our results provide evidence for a link between DNA damage–induced checkpoint activation and translesion synthesis in mammalian cells.
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Affiliation(s)
- Thomas Göhler
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, England, UK
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26
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Woodruff RV, Bomar MG, D'Souza S, Zhou P, Walker GC. The unusual UBZ domain of Saccharomyces cerevisiae polymerase η. DNA Repair (Amst) 2010; 9:1130-41. [PMID: 20837403 DOI: 10.1016/j.dnarep.2010.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 07/19/2010] [Accepted: 08/02/2010] [Indexed: 11/25/2022]
Abstract
Recent research has revealed the presence of ubiquitin-binding domains in the Y family polymerases. The ubiquitin-binding zinc finger (UBZ) domain of human polymerase η is vital for its regulation, localization, and function. Here, we elucidate structural and functional features of the non-canonical UBZ motif of Saccharomyces cerevisiae pol η. Characterization of pol η mutants confirms the importance of the UBZ motif and implies that its function is independent of zinc binding. Intriguingly, we demonstrate that zinc does bind to and affect the structure of the purified UBZ domain, but is not required for its ubiquitin-binding activity. Our finding that this unusual zinc finger is able to interact with ubiquitin even in its apo form adds support to the model that ubiquitin binding is the primary and functionally important activity of the UBZ domain in S. cerevisiae polymerase η. Putative ubiquitin-binding domains, primarily UBZs, are identified in the majority of known pol η homologs. We discuss the implications of our observations for zinc finger structure and pol η regulation.
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Affiliation(s)
- Rachel V Woodruff
- Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA
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