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REV7 in Cancer Biology and Management. Cancers (Basel) 2023; 15:cancers15061721. [PMID: 36980607 PMCID: PMC10046837 DOI: 10.3390/cancers15061721] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 03/18/2023] Open
Abstract
DNA repair and cell cycle regulation are potential biological fields to develop molecular targeting therapies for cancer. Human REV7 was originally discovered as a homologous molecule to yeast Rev7, which is involved in DNA damage response and mutagenesis, and as the second homolog of yeast Mad2, involved in the spindle assembly checkpoint. Although REV7 principally functions in the fields of DNA repair and cell cycle regulation, many binding partners of REV7 have been identified using comprehensive analyses in the past decade, and the significance of REV7 is expanding in various other biological fields, such as gene transcription, epigenetics, primordial germ cell survival, neurogenesis, intracellular signaling, and microbial infection. In addition, the clinical significance of REV7 has been demonstrated in studies using human cancer tissues, and investigations in cancer cell lines and animal models have revealed the greater impacts of REV7 in cancer biology, which makes it an attractive target molecule for cancer management. This review focuses on the functions of REV7 in human cancer and discusses the utility of REV7 for cancer management with a summary of the recent development of inhibitors targeting REV7.
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2
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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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3
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Takezawa J, Shimazaki A, Takimoto H, Kajiwara K, Yamada K. A large intermediate domain of vertebrate REV3 protein is dispensable for ultraviolet-induced translesion replication. DNA Repair (Amst) 2020; 98:103031. [PMID: 33387704 DOI: 10.1016/j.dnarep.2020.103031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 11/24/2022]
Abstract
DNA polymerase ζ (pol ζ) is involved in translesion replication (translesion synthesis, TLS) and plays an essential role in embryogenesis. In adults, pol ζ triggers mutation as a result of error-prone TLS and causes carcinogenesis. The catalytic subunit of pol ζ, REV3, is evolutionarily conserved from yeast and plants to higher eukaryotes. However, the structures are notably different: unlike that in yeast REV3, a large intermediate domain is inserted in REV3 of humans and mice. The domain is mostly occupied with noncommittal structures (random coil…etc.); therefore, its role and function are yet to be resolved. Previously, we reported deficient levels of ultraviolet (UV)-induced TLS in fibroblasts derived from the Rev3-knockout mouse embryo (Rev3KO-MEF). Here, we constructed a mouse Rev3-expressing plasmid with a deleted intermediate domain (532-1793 a.a,) and transfected it into Rev3KO-MEF. The isolated stable transformants showed comparable levels of UV-sensitivity and UV-TLS activity to those in wild-type MEF, detected using an alkaline sucrose density gradient sedimentation. These results indicate that the intermediate domain is nonessential for UV-induced translesion replication in cultured mouse cells.
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Affiliation(s)
- Jun Takezawa
- Department of Genetic Biochemistry, The National Institutes of Biomedical Innovation, Health and Nutrition, Toyama 1-23-1, Shinjuku-ku, Tokyo, 162-8636, Japan
| | - Anna Shimazaki
- Department of Genetic Biochemistry, The National Institutes of Biomedical Innovation, Health and Nutrition, Toyama 1-23-1, Shinjuku-ku, Tokyo, 162-8636, Japan
| | - Hidemi Takimoto
- Department of Nutritional Epidemiology and Shoku-iku, The National Institutes of Biomedical Innovation, Health and Nutrition, Toyama 1-23-1, Shinjuku-ku, Tokyo, 162-8636, Japan
| | | | - Kouichi Yamada
- Department of Genetic Biochemistry, The National Institutes of Biomedical Innovation, Health and Nutrition, Toyama 1-23-1, Shinjuku-ku, Tokyo, 162-8636, Japan.
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4
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Ma X, Tang TS, Guo C. Regulation of translesion DNA synthesis in mammalian cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:680-692. [PMID: 31983077 DOI: 10.1002/em.22359] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/29/2019] [Accepted: 01/21/2020] [Indexed: 06/10/2023]
Abstract
The genomes of all living cells are under endogenous and exogenous attacks every day, causing diverse genomic lesions. Most of the lesions can be timely repaired by multiple DNA repair pathways. However, some may persist during S-phase, block DNA replication, and challenge genome integrity. Eukaryotic cells have evolved DNA damage tolerance (DDT) to mitigate the lethal effects of arrested DNA replication without prior removal of the offending DNA damage. As one important mode of DDT, translesion DNA synthesis (TLS) utilizes multiple low-fidelity DNA polymerases to incorporate nucleotides opposite DNA lesions to maintain genome integrity. Three different mechanisms have been proposed to regulate the polymerase switching between high-fidelity DNA polymerases in the replicative machinery and one or more specialized enzymes. Additionally, it is known that proliferating cell nuclear antigen (PCNA) mono-ubiquitination is essential for optimal TLS. Given its error-prone property, TLS is closely associated with spontaneous and drug-induced mutations in cells, which can potentially lead to tumorigenesis and chemotherapy resistance. Therefore, TLS process must be tightly modulated to avoid unwanted mutagenesis. In this review, we will focus on polymerase switching and PCNA mono-ubiquitination, the two key events in TLS pathway in mammalian cells, and summarize current understandings of regulation of TLS process at the levels of protein-protein interactions, post-translational modifications as well as transcription and noncoding RNAs. Environ. Mol. Mutagen. 61:680-692, 2020. © 2020 Wiley Periodicals, Inc.
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Affiliation(s)
- Xiaolu Ma
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Tie-Shan Tang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Caixia Guo
- CAS Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
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5
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van Bostelen I, van Schendel R, Romeijn R, Tijsterman M. Translesion synthesis polymerases are dispensable for C. elegans reproduction but suppress genome scarring by polymerase theta-mediated end joining. PLoS Genet 2020; 16:e1008759. [PMID: 32330130 PMCID: PMC7202663 DOI: 10.1371/journal.pgen.1008759] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/06/2020] [Accepted: 04/06/2020] [Indexed: 12/30/2022] Open
Abstract
Bases within DNA are frequently damaged, producing obstacles to efficient and accurate DNA replication by replicative polymerases. Translesion synthesis (TLS) polymerases, via their ability to catalyze nucleotide additions to growing DNA chains across DNA lesions, promote replication of damaged DNA, thus preventing checkpoint activation, genome instability and cell death. In this study, we used C. elegans to determine the contribution of TLS activity on long-term stability of an animal genome. We monitored and compared the types of mutations that accumulate in REV1, REV3, POLH1 and POLK deficient animals that were grown under unchallenged conditions. We also addressed redundancies in TLS activity by combining all deficiencies. Remarkably, animals that are deficient for all Y-family polymerases as well as animals that have lost all TLS activity are viable and produce progeny, demonstrating that TLS is not essential for animal life. Whole genome sequencing analyses, however, reveal that TLS is needed to prevent genomic scars from accumulating. These scars, which are the product of polymerase theta-mediated end joining (TMEJ), are found overrepresented at guanine bases, consistent with TLS suppressing DNA double-strand breaks (DSBs) from occurring at replication-blocking guanine adducts. We found that in C. elegans, TLS across spontaneous damage is predominantly error free and anti-clastogenic, and thus ensures preservation of genetic information.
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Affiliation(s)
- Ivo van Bostelen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Ron Romeijn
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
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6
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Sasatani M, Zaharieva EK, Kamiya K. The in vivo role of Rev1 in mutagenesis and carcinogenesis. Genes Environ 2020; 42:9. [PMID: 32161626 PMCID: PMC7048032 DOI: 10.1186/s41021-020-0148-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/05/2020] [Indexed: 11/23/2022] Open
Abstract
Translesion synthesis (TLS) is an error-prone pathway required to overcome replication blockage by DNA damage. Aberrant activation of TLS has been suggested to play a role in tumorigenesis by promoting genetic mutations. However, the precise molecular mechanisms underlying TLS-mediated tumorigenesis in vivo remain unclear. Rev1 is a member of the Y family polymerases and plays a key role in the TLS pathway. Here we introduce the existing to date Rev1-mutated mouse models, including the Rev1 transgenic (Tg) mouse model generated in our laboratory. We give an overview of the current knowledge on how different disruptions in Rev1 functions impact mutagenesis and the suggested molecular mechanisms underlying these effects. We summarize the available data from ours and others’ in vivo studies on the role of Rev1 in the initiation and promotion of cancer, emphasizing how Rev1-mutated mouse models can be used as complementary tools for future research.
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Affiliation(s)
- Megumi Sasatani
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553 Japan
| | - Elena Karamfilova Zaharieva
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553 Japan
| | - Kenji Kamiya
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553 Japan
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7
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Sasatani M, Xi Y, Kajimura J, Kawamura T, Piao J, Masuda Y, Honda H, Kubo K, Mikamoto T, Watanabe H, Xu Y, Kawai H, Shimura T, Noda A, Hamasaki K, Kusunoki Y, Zaharieva EK, Kamiya K. Overexpression of Rev1 promotes the development of carcinogen-induced intestinal adenomas via accumulation of point mutation and suppression of apoptosis proportionally to the Rev1 expression level. Carcinogenesis 2017; 38:570-578. [PMID: 28498946 PMCID: PMC5872566 DOI: 10.1093/carcin/bgw208] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cancer development often involves mutagenic replication of damaged DNA by the error-prone translesion synthesis (TLS) pathway. Aberrant activation of this pathway plays a role in tumorigenesis by promoting genetic mutations. Rev1 controls the function of the TLS pathway, and Rev1 expression levels are associated with DNA damage induced cytotoxicity and mutagenicity. However, it remains unclear whether deregulated Rev1 expression triggers or promotes tumorigenesis in vivo. In this study, we generated a novel Rev1-overexpressing transgenic (Tg) mouse and characterized its susceptibility to tumorigenesis. Using a small intestinal tumor model induced by N-methyl-N-nitrosourea (MNU), we found that transgenic expression of Rev1 accelerated intestinal adenoma development in proportion to the Rev1 expression level; however, overexpression of Rev1 alone did not cause spontaneous development of intestinal adenomas. In Rev1 Tg mice, MNU-induced mutagenesis was elevated, whereas apoptosis was suppressed. The effects of hREV1 expression levels on the cytotoxicity and mutagenicity of MNU were confirmed in the human cancer cell line HT1080. These data indicate that dysregulation of cellular Rev1 levels leads to the accumulation of mutations and suppression of cell death, which accelerates the tumorigenic activities of DNA-damaging agents.
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Affiliation(s)
- Megumi Sasatani
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Yang Xi
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan.,Diabetes Center, Zhejiang Provincial Key Laboratory of Pathophysiology, Institute of Biochemistry and Molecular Biology, School of Medicine, Ningbo University, Ningbo 315211, China
| | - Junko Kajimura
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan.,Department of Molecular Biosciences, Radiation Effects Research Foundation, Hiroshima 732-0815, Japan
| | - Toshiyuki Kawamura
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Jinlian Piao
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Yuji Masuda
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan.,Department of Genome Dynamics, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan.,Department of Toxicogenomics, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroaki Honda
- Department of Disease Model, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Kei Kubo
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Takahiro Mikamoto
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Hiromitsu Watanabe
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Yanbin Xu
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Hidehiko Kawai
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Tsutomu Shimura
- Department of Environmental Health, National Institute of Public Health, 2-3-6, Minami, Wako, Saitama 351-0197, Japan and
| | - Asao Noda
- Department of Molecular Biosciences, Radiation Effects Research Foundation, Hiroshima 732-0815, Japan
| | - Kanya Hamasaki
- Department of Molecular Biosciences, Radiation Effects Research Foundation, Hiroshima 732-0815, Japan
| | - Yoichiro Kusunoki
- Department of Molecular Biosciences, Radiation Effects Research Foundation, Hiroshima 732-0815, Japan
| | - Elena Karamfilova Zaharieva
- Department of Genetics and Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Kenji Kamiya
- Department of Experimental Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
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8
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Prasad R, Poltoratsky V, Hou EW, Wilson SH. Rev1 is a base excision repair enzyme with 5'-deoxyribose phosphate lyase activity. Nucleic Acids Res 2016; 44:10824-10833. [PMID: 27683219 PMCID: PMC5159550 DOI: 10.1093/nar/gkw869] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 09/16/2016] [Accepted: 09/21/2016] [Indexed: 12/28/2022] Open
Abstract
Rev1 is a member of the Y-family of DNA polymerases and is known for its deoxycytidyl transferase activity that incorporates dCMP into DNA and its ability to function as a scaffold factor for other Y-family polymerases in translesion bypass events. Rev1 also is involved in mutagenic processes during somatic hypermutation of immunoglobulin genes. In light of the mutation pattern consistent with dCMP insertion observed earlier in mouse fibroblast cells treated with a base excision repair-inducing agent, we questioned whether Rev1 could also be involved in base excision repair (BER). Here, we uncovered a weak 5′-deoxyribose phosphate (5′-dRP) lyase activity in mouse Rev1 and demonstrated the enzyme can mediate BER in vitro. The full-length Rev1 protein and its catalytic core domain are similar in their ability to support BER in vitro. The dRP lyase activity in both of these proteins was confirmed by NaBH4 reduction of the Schiff base intermediate and kinetics studies. Limited proteolysis, mass spectrometry and deletion analysis localized the dRP lyase active site to the C-terminal segment of Rev1's catalytic core domain. These results suggest that Rev1 could serve as a backup polymerase in BER and could potentially contribute to AID-initiated antibody diversification through this activity.
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Affiliation(s)
- Rajendra Prasad
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, PO Box 12233, MD F3-01, Research Triangle Park, NC 27709, USA
| | - Vladimir Poltoratsky
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, PO Box 12233, MD F3-01, Research Triangle Park, NC 27709, USA
| | - Esther W Hou
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, PO Box 12233, MD F3-01, Research Triangle Park, NC 27709, USA
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institutes of Health, NIEHS, 111 T.W. Alexander Drive, PO Box 12233, MD F3-01, Research Triangle Park, NC 27709, USA
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9
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Suzuki T, Grúz P, Honma M, Adachi N, Nohmi T. The role of DNA polymerase ζ in translesion synthesis across bulky DNA adducts and cross-links in human cells. Mutat Res 2016; 791-792:35-41. [PMID: 27591392 DOI: 10.1016/j.mrfmmm.2016.08.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 08/17/2016] [Accepted: 08/24/2016] [Indexed: 06/06/2023]
Abstract
Translesion DNA synthesis (TLS) is a cellular defense mechanism against genotoxins. Defects or mutations in specialized DNA polymerases (Pols) involved in TLS are believed to result in hypersensitivity to various genotoxic stresses. Here, DNA polymerase ζ (Pol ζ)-deficient (KO: knockout) and Pol ζ catalytically dead (CD) human cells were established and their sensitivity towards cytotoxic activities of various genotoxins was examined. The CD cells were engineered by altering the DNA sequence encoding two amino acids essential for the catalytic activity of Pol ζ, i.e., D2781 and D2783, to alanines. Both Pol ζ KO and CD cells displayed a prolonged cell cycle and higher incidence of micronuclei formation than the wild-type (WT) cells in the absence of exogenous genotoxic treatments, and the order of abnormality was CD>KO>WT cells. Both KO and CD cells exhibited higher sensitivity towards the killing effects of benzo[a]pyrene diol epoxide, mitomycin C, potassium bromate, N-methyl-N'-nitro-N-nitrosoguanidine, and ultraviolet C irradiation than WT cells, and there were no differences between the sensitivities of KO and CD cells. Interestingly, neither KO nor CD cells were sensitive to the cytotoxic effects of hydrogen peroxide. Since KO and CD cells displayed similar sensitivities to the genotoxins, we employed only KO cells to further examine their sensitivity to other genotoxic agents. KO cells were more sensitive to the cytotoxicity of 4-nitroquinoline N-oxide, styrene oxide, cisplatin, methyl methanesulfonate, and ethyl methanesulfonate than WT cells. However, the KO cells displayed sensitivity camptothecin, etoposide, bleomycin, hydroxyurea, crotonealdehyde, and methylglyoxal in a manner similar to the WT cells. Our results suggest that Pol ζ plays an important role in the protection of human cells by carrying out TLS across bulky DNA adducts and cross-links, but has no or limited role in the protection against strand-breaks in DNA.
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Affiliation(s)
- Tetsuya Suzuki
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
| | - Petr Grúz
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Masamitsu Honma
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
| | - Noritaka Adachi
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan
| | - Takehiko Nohmi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
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10
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Korzhnev DM, Hadden MK. Targeting the Translesion Synthesis Pathway for the Development of Anti-Cancer Chemotherapeutics. J Med Chem 2016; 59:9321-9336. [PMID: 27362876 DOI: 10.1021/acs.jmedchem.6b00596] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Human cells possess tightly controlled mechanisms to rescue DNA replication following DNA damage caused by environmental and endogenous carcinogens using a set of low-fidelity translesion synthesis (TLS) DNA polymerases. These polymerases can copy over replication blocking DNA lesions while temporarily leaving them unrepaired, preventing cell death at the expense of increasing mutation rates and contributing to the onset and progression of cancer. In addition, TLS has been implicated as a major cellular mechanism promoting acquired resistance to genotoxic chemotherapy. Owing to its central role in mutagenesis and cell survival after DNA damage, inhibition of the TLS pathway has emerged as a potential target for the development of anticancer agents. This review will recap our current understanding of the structure and regulation of DNA polymerase complexes that mediate TLS and describe how this knowledge is beginning to translate into the development of small molecule TLS inhibitors.
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Affiliation(s)
- Dmitry M Korzhnev
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center , Farmington, Connecticut 06030, United States
| | - M Kyle Hadden
- Department of Pharmaceutical Sciences, University of Connecticut , 69 North Eagleville Road, Unit 3092, Storrs, Connecticut 06269, United States
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11
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Tsai RYL. Balancing self-renewal against genome preservation in stem cells: How do they manage to have the cake and eat it too? Cell Mol Life Sci 2016; 73:1803-23. [PMID: 26886024 PMCID: PMC5040593 DOI: 10.1007/s00018-016-2152-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/18/2016] [Accepted: 01/28/2016] [Indexed: 01/22/2023]
Abstract
Stem cells are endowed with the awesome power of self-renewal and multi-lineage differentiation that allows them to be major contributors to tissue homeostasis. Owing to their longevity and self-renewal capacity, they are also faced with a higher risk of genomic damage compared to differentiated cells. Damage on the genome, if not prevented or repaired properly, will threaten the survival of stem cells and culminate in organ failure, premature aging, or cancer formation. It is therefore of paramount importance that stem cells remain genomically stable throughout life. Given their unique biological and functional requirement, stem cells are thought to manage genotoxic stress somewhat differently from non-stem cells. The focus of this article is to review the current knowledge on how stem cells escape the barrage of oxidative and replicative DNA damage to stay in self-renewal. A clear statement on this subject should help us better understand tissue regeneration, aging, and cancer.
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Affiliation(s)
- Robert Y L Tsai
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, 2121 W. Holcombe Blvd, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, College Station, TX, 77843, USA.
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12
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Wang K, Ma X, Zhang X, Wu D, Sun C, Sun Y, Lu X, Wu CI, Guo C, Ruan J. Using ultra-sensitive next generation sequencing to dissect DNA damage-induced mutagenesis. Sci Rep 2016; 6:25310. [PMID: 27122023 PMCID: PMC4848531 DOI: 10.1038/srep25310] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/13/2016] [Indexed: 12/17/2022] Open
Abstract
Next generation sequencing (NGS) technologies have dramatically improved studies in biology and biomedical science. However, no optimal NGS approach is available to conveniently analyze low frequency mutations caused by DNA damage treatments. Here, by developing an exquisite ultra-sensitive NGS (USNGS) platform “EasyMF” and incorporating it with a widely used supF shuttle vector-based mutagenesis system, we can conveniently dissect roles of lesion bypass polymerases in damage-induced mutagenesis. In this improved mutagenesis analysis pipeline, the initial steps are the same as in the supF mutation assay, involving damaging the pSP189 plasmid followed by its transfection into human 293T cells to allow replication to occur. Then “EasyMF” is employed to replace downstream MBM7070 bacterial transformation and other steps for analyzing damage-induced mutation frequencies and spectra. This pipeline was validated by using UV damaged plasmid after its replication in lesion bypass polymerase-deficient 293T cells. The increased throughput and reduced cost of this system will allow us to conveniently screen regulators of translesion DNA synthesis pathway and monitor environmental genotoxic substances, which can ultimately provide insight into the mechanisms of genome stability and mutagenesis.
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Affiliation(s)
- Kaile Wang
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaolu Ma
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xue Zhang
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Dafei Wu
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Chenyi Sun
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yazhou Sun
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xuemei Lu
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Chung-I Wu
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.,Department of Ecology and Evolution, University of Chicago, USA
| | - Caixia Guo
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jue Ruan
- Key Laboratory of Genomics and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
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13
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USP7 is essential for maintaining Rad18 stability and DNA damage tolerance. Oncogene 2015; 35:965-76. [PMID: 25961918 DOI: 10.1038/onc.2015.149] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 03/04/2015] [Accepted: 03/06/2015] [Indexed: 01/08/2023]
Abstract
Rad18 functions at the cross-roads of three different DNA damage response (DDR) pathways involved in protecting stressed replication forks: homologous recombination repair, DNA inter-strand cross-link repair and DNA damage tolerance. Although Rad18 serves to facilitate replication of damaged genomes by promoting translesion synthesis (TLS), this comes at a cost of potentially error-prone lesion bypass. In contrast, loss of Rad18-dependent TLS potentiates the collapse of stalled forks and leads to incomplete genome replication. Given the pivotal nature with which Rad18 governs the fine balance between replication fidelity and genome stability, Rad18 levels and activity have a major impact on genomic integrity. Here, we identify the de-ubiquitylating enzyme USP7 as a critical regulator of Rad18 protein levels. Loss of USP7 destabilizes Rad18 and compromises UV-induced PCNA mono-ubiquitylation and Pol η recruitment to stalled replication forks. USP7-depleted cells also fail to elongate nascent daughter strand DNA following UV irradiation and show reduced DNA damage tolerance. We demonstrate that USP7 associates with Rad18 directly via a consensus USP7-binding motif and can disassemble Rad18-dependent poly-ubiquitin chains both in vitro and in vivo. Taken together, these observations identify USP7 as a novel component of the cellular DDR involved in preserving the genome stability.
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14
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Jansen JG, Tsaalbi-Shtylik A, de Wind N. Roles of mutagenic translesion synthesis in mammalian genome stability, health and disease. DNA Repair (Amst) 2015; 29:56-64. [PMID: 25655219 DOI: 10.1016/j.dnarep.2015.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/22/2014] [Accepted: 01/07/2015] [Indexed: 01/08/2023]
Abstract
Most spontaneous and DNA damage-induced nucleotide substitutions in eukaryotes depend on translesion synthesis polymerases Rev1 and Pol ζ, the latter consisting of the catalytic subunit Rev3 and the accessory protein Rev7. Here we review the regulation, and the biochemical and cellular functions, of Rev1/Pol ζ-dependent translesion synthesis. These are correlated with phenotypes of mouse models with defects in Rev1, Rev3 or Rev7. The data indicate that Rev1/Pol ζ-mediated translesion synthesis is important for adaptive immunity while playing paradoxical roles in oncogenesis. On the other hand, by enabling the replication of endogenously damaged templates, Rev1/Pol ζ -dependent translesion synthesis protects stem cells, thereby preventing features of ageing. In conclusion, Rev1/Pol ζ-dependent translesion synthesis at DNA helix-distorting nucleotide lesions orchestrates pleiotropic responses that determine organismal fitness and disease.
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Affiliation(s)
- Jacob G Jansen
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Anastasia Tsaalbi-Shtylik
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands
| | - Niels de Wind
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300RC Leiden, The Netherlands.
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15
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Mao L, Verwoerd WS. Exploration and comparison of inborn capacity of aerobic and anaerobic metabolisms of Saccharomyces cerevisiae for microbial electrical current production. Bioengineered 2013; 4:420-30. [PMID: 23969939 PMCID: PMC3937204 DOI: 10.4161/bioe.26222] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Saccharomyces cerevisiae possesses numerous advantageous biological features, such as being robust, easily handled, mostly non-pathogenic and having high catabolic rates, etc., which can be considered as merits for being used as a promising biocatalyst in microbial fuel cells (MFCs) for electricity generation. Previous studies have developed efficient MFC configurations to convert metabolic electron shuttles, such as cytoplasmic NADH, into usable electric current. However, no studies have elucidated the maximum potential of S. cerevisiae for current output and the underlying metabolic pathways, resulting from the interaction of thousands of reactions inside the cell during MFC operation. To address these two key issues, this study used in silico metabolic engineering techniques, flux balance analysis (FBA), and flux variability analysis with target flux minimization (FATMIN), to model the metabolic perturbation of S. cerevisiae under the MFC-energy extraction. The FBA results showed that, in the cytoplasmic NADH-dependent mediated electron transfer (MET) mode, S. cerevisiae had a potential to produce currents at up to 5.781 A/gDW for the anaerobic and 6.193 A/gDW for the aerobic environments. The FATMIN results showed that the aerobic and anaerobic metabolisms are resilient, relying on six and five contributing reactions respectively for high current production. Two reactions, catalyzed by glutamate dehydrogenase (NAD) (EC 1.4.1.3) and methylene tetrahydrofolate dehydrogenase (NAD) (EC 1.5.1.5), were shared in both current-production modes and contributed to over 80% of the identified maximum current outputs. It is also shown that the NADH regeneration was much less energy costly than biomass production rate. Taken together, our finding suggests that S. cerevisiae should receive more research effort for MFC electricity production.
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Affiliation(s)
- Longfei Mao
- Centre for Advanced Computational Solutions; Department of Molecular Biosciences; Lincoln University; Lincoln, New Zealand
| | - Wynand S Verwoerd
- Centre for Advanced Computational Solutions; Department of Molecular Biosciences; Lincoln University; Lincoln, New Zealand
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16
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Abstract
The structural features that enable replicative DNA polymerases to synthesize DNA rapidly and accurately also limit their ability to copy damaged DNA. Direct replication of DNA damage is termed translesion synthesis (TLS), a mechanism conserved from bacteria to mammals and executed by an array of specialized DNA polymerases. This chapter examines how these translesion polymerases replicate damaged DNA and how they are regulated to balance their ability to replicate DNA lesions with the risk of undesirable mutagenesis. It also discusses how TLS is co-opted to increase the diversity of the immunoglobulin gene hypermutation and the contribution it makes to the mutations that sculpt the genome of cancer cells.
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Affiliation(s)
- Julian E Sale
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom.
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17
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Pryor JM, Gakhar L, Washington MT. Structure and functional analysis of the BRCT domain of translesion synthesis DNA polymerase Rev1. Biochemistry 2013; 52:254-63. [PMID: 23240687 PMCID: PMC3580236 DOI: 10.1021/bi301572z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Translesion synthesis (TLS) is a pathway in which specialized, low-fidelity DNA polymerases are used to overcome replication blocks caused by DNA damage. The use of this pathway often results in somatic mutations that can drive carcinogenesis. Rev1 is a TLS polymerase found in all eukaryotes that plays a pivotal role in mediating DNA damage-induced mutagenesis. It possesses a BRCA1 C-terminal (BRCT) domain that is required for its function. The rev1-1 allele encodes a mutant form of Rev1 with a G193R substitution in this domain, which reduces the level of DNA damage-induced mutagenesis. Despite its clear importance in mutagenic TLS, the role of the BRCT domain is unknown. Here, we report the X-ray crystal structure of the yeast Rev1 BRCT domain and show that substitutions in residues constituting its phosphate-binding pocket do not affect mutagenic TLS. This suggests that the role of the Rev1 BRCT domain is not to recognize phosphate groups on protein binding partners or on DNA. We also found that residue G193 is located in a conserved turn region of the BRCT domain, and our in vivo and in vitro studies suggest that the G193R substitution may disrupt Rev1 function by destabilizing the fold of the BRCT domain.
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Affiliation(s)
- John M. Pryor
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Lokesh Gakhar
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
- Protein Crystallography Facility, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - M. Todd Washington
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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18
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Sharma S, Helchowski CM, Canman CE. The roles of DNA polymerase ζ and the Y family DNA polymerases in promoting or preventing genome instability. Mutat Res 2012. [PMID: 23195997 DOI: 10.1016/j.mrfmmm.2012.11.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cancer cells display numerous abnormal characteristics which are initiated and maintained by elevated mutation rates and genome instability. Chromosomal DNA is continuously surveyed for the presence of damage or blocked replication forks by the DNA Damage Response (DDR) network. The DDR is complex and includes activation of cell cycle checkpoints, DNA repair, gene transcription, and induction of apoptosis. Duplicating a damaged genome is associated with elevated risks to fork collapse and genome instability. Therefore, the DNA damage tolerance (DDT) pathway is also employed to enhance survival and involves the recruitment of translesion DNA synthesis (TLS) polymerases to sites of replication fork blockade or single stranded DNA gaps left after the completion of replication in order to restore DNA to its double stranded form before mitosis. TLS polymerases are specialized for inserting nucleotides opposite DNA adducts, abasic sites, or DNA crosslinks. By definition, the DDT pathway is not involved in the actual repair of damaged DNA, but provides a mechanism to tolerate DNA lesions during replication thereby increasing survival and lessening the chance for genome instability. However this may be associated with increased mutagenesis. In this review, we will describe the specialized functions of Y family polymerases (Rev1, Polη, Polι and Polκ) and DNA polymerase ζ in lesion bypass, mutagenesis, and prevention of genome instability, the latter due to newly appreciated roles in DNA repair. The recently described role of the Fanconi anemia pathway in regulating Rev1 and Polζ-dependent TLS is also discussed in terms of their involvement in TLS, interstrand crosslink repair, and homologous recombination.
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Affiliation(s)
- Shilpy Sharma
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Corey M Helchowski
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Christine E Canman
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, United States.
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19
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Kuang L, Kou H, Xie Z, Zhou Y, Feng X, Wang L, Wang Z. A non-catalytic function of Rev1 in translesion DNA synthesis and mutagenesis is mediated by its stable interaction with Rad5. DNA Repair (Amst) 2012; 12:27-37. [PMID: 23142547 DOI: 10.1016/j.dnarep.2012.10.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 09/22/2012] [Accepted: 10/12/2012] [Indexed: 01/05/2023]
Abstract
DNA damage tolerance consisting of template switching and translesion synthesis is a major cellular mechanism in response to unrepaired DNA lesions during replication. The Rev1 pathway constitutes the major mechanism of translesion synthesis and base damage-induced mutagenesis in model cell systems. Rev1 is a dCMP transferase, but additionally plays non-catalytic functions in translesion synthesis. Using the yeast model system, we attempted to gain further insights into the non-catalytic functions of Rev1. Rev1 stably interacts with Rad5 (a central component of the template switching pathway) via the C-terminal region of Rev1 and the N-terminal region of Rad5. Supporting functional significance of this interaction, both the Rev1 pathway and Rad5 are required for translesion synthesis and mutagenesis of 1,N(6)-ethenoadenine. Furthermore, disrupting the Rev1-Rad5 interaction by mutating Rev1 did not affect its dCMP transferase, but led to inactivation of the Rev1 non-catalytic function in translesion synthesis of UV-induced DNA damage. Deletion analysis revealed that the C-terminal 21-amino acid sequence of Rev1 is uniquely required for its interaction with Rad5 and is essential for its non-catalytic function. Deletion analysis additionally implicated a C-terminal region of Rev1 in its negative regulation. These results show that a non-catalytic function of Rev1 in translesion synthesis and mutagenesis is mediated by its interaction with Rad5.
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Affiliation(s)
- Lisha Kuang
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
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20
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Suzuki M, Takahashi T. Aberrant DNA replication in cancer. Mutat Res 2012; 743-744:111-117. [PMID: 22968031 DOI: 10.1016/j.mrfmmm.2012.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 07/26/2012] [Accepted: 07/31/2012] [Indexed: 12/11/2022]
Abstract
Genomic instability plays an important role in cancer susceptibility, though the mechanics of its development remain unclear. An often-stated hypothesis is that error-prone phenotypes in DNA replication or aberrations in translesion DNA synthesis lead to genomic instability and cancer. Mutations in core DNA replication proteins have been identified in human cancer, although DNA replication is essential for cell proliferation and most mutations eliminating this function are deleterious. With recent developments in this field we review and discuss the possible involvement of DNA replication proteins in carcinogenesis.
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Affiliation(s)
- Motoshi Suzuki
- Division of Molecular Carcinogenesis, Nagoya University Graduate School of Medicine, Nagoya, Japan.
| | - Takashi Takahashi
- Division of Molecular Carcinogenesis, Nagoya University Graduate School of Medicine, Nagoya, Japan
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21
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Pozhidaeva A, Pustovalova Y, D'Souza S, Bezsonova I, Walker GC, Korzhnev DM. NMR structure and dynamics of the C-terminal domain from human Rev1 and its complex with Rev1 interacting region of DNA polymerase η. Biochemistry 2012; 51:5506-20. [PMID: 22691049 DOI: 10.1021/bi300566z] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Rev1 is a translesion synthesis (TLS) DNA polymerase essential for DNA damage tolerance in eukaryotes. In the process of TLS stalled high-fidelity replicative DNA polymerases are temporarily replaced by specialized TLS enzymes that can bypass sites of DNA damage (lesions), thus allowing replication to continue or postreplicational gaps to be filled. Despite its limited catalytic activity, human Rev1 plays a key role in TLS by serving as a scaffold that provides an access of Y-family TLS polymerases polη, ι, and κ to their cognate DNA lesions and facilitates their subsequent exchange to polζ that extends the distorted DNA primer-template. Rev1 interaction with the other major human TLS polymerases, polη, ι, κ, and the regulatory subunit Rev7 of polζ, is mediated by Rev1 C-terminal domain (Rev1-CT). We used NMR spectroscopy to determine the spatial structure of the Rev1-CT domain (residues 1157-1251) and its complex with Rev1 interacting region (RIR) from polη (residues 524-539). The domain forms a four-helix bundle with a well-structured N-terminal β-hairpin docking against helices 1 and 2, creating a binding pocket for the two conserved Phe residues of the RIR motif that upon binding folds into an α-helix. NMR spin-relaxation and NMR relaxation dispersion measurements suggest that free Rev1-CT and Rev1-CT/polη-RIR complex exhibit μs-ms conformational dynamics encompassing the RIR binding site, which might facilitate selection of the molecular configuration optimal for binding. These results offer new insights into the control of TLS in human cells by providing a structural basis for understanding the recognition of the Rev1-CT by Y-family DNA polymerases.
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Affiliation(s)
- Alexandra Pozhidaeva
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, 06030, United States
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22
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Hashimoto K, Cho Y, Yang IY, Akagi JI, Ohashi E, Tateishi S, de Wind N, Hanaoka F, Ohmori H, Moriya M. The vital role of polymerase ζ and REV1 in mutagenic, but not correct, DNA synthesis across benzo[a]pyrene-dG and recruitment of polymerase ζ by REV1 to replication-stalled site. J Biol Chem 2012; 287:9613-22. [PMID: 22303021 DOI: 10.1074/jbc.m111.331728] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The DNA synthesis across DNA lesions, termed translesion synthesis (TLS), is a complex process influenced by various factors. To investigate this process in mammalian cells, we examined TLS across a benzo[a]pyrene dihydrodiol epoxide-derived dG adduct (BPDE-dG) using a plasmid bearing a single BPDE-dG and genetically engineered mouse embryonic fibroblasts (MEFs). In wild-type MEFs, TLS was extremely miscoding (>90%) with G → T transversions being predominant. Knockout of the Rev1 gene decreased both the TLS efficiency and the miscoding frequency. Knockout of the Rev3L gene, coding for the catalytic subunit of pol ζ, caused even greater decreases in these two TLS parameters; almost all residual TLS were error-free. Thus, REV1 and pol ζ are critical to mutagenic, but not accurate, TLS across BPDE-dG. The introduction of human REV1 cDNA into Rev1(-/-) MEFs restored the mutagenic TLS, but a REV1 mutant lacking the C terminus did not. Yeast and mammalian three-hybrid assays revealed that the REV7 subunit of pol ζ mediated the interaction between REV3 and the REV1 C terminus. These results support the hypothesis that REV1 recruits pol ζ through the interaction with REV7. Our results also predict the existence of a minor REV1-independent pol ζ recruitment pathway. Finally, although mutagenic TLS across BPDE-dG largely depends on RAD18, experiments using Polk(-/-) Polh(-/-) Poli(-/-) triple-gene knockout MEFs unexpectedly revealed that another polymerase(s) could insert a nucleotide opposite BPDE-dG. This indicates that a non-Y family polymerase(s) can insert a nucleotide opposite BPDE-dG, but the subsequent extension from miscoding termini depends on REV1-polζ in a RAD18-dependent manner.
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Affiliation(s)
- Keiji Hashimoto
- Department of Pharmacological Sciences, State University of New York, Stony Brook, New York 11794-8651, USA
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23
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Takezawa J, Aiba N, Kajiwara K, Yamada K. Caffeine abolishes the ultraviolet-induced REV3 translesion replication pathway in mouse cells. Int J Mol Sci 2011; 12:8513-29. [PMID: 22272088 PMCID: PMC3257085 DOI: 10.3390/ijms12128513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/08/2011] [Accepted: 11/17/2011] [Indexed: 11/26/2022] Open
Abstract
When a replicative DNA polymerase stalls upon encountering a photoproduct on the template strand, it is relieved by other low-processivity polymerase(s), which insert nucleotide(s) opposite the lesion. Using an alkaline sucrose density gradient sedimentation technique, we previously classified this process termed UV-induced translesion replication (UV-TLS) into two types. In human cancer cells or xeroderma pigmentosum variant (XP-V) cells, UV-TLS was inhibited by caffeine or proteasome inhibitors. However, in normal human cells, the process was insensitive to these reagents. Reportedly, in yeast or mammalian cells, REV3 protein (a catalytic subunit of DNA polymerase ζ) is predominantly involved in the former type of TLS. Here, we studied UV-TLS in fibroblasts derived from the Rev3-knockout mouse embryo (Rev3KO-MEF). In the wild-type MEF, UV-TLS was slow (similar to that of human cancer cells or XP-V cells), and was abolished by caffeine or MG-262. In 2 cell lines of Rev3KO-MEF (Rev3−/−p53−/−), UV-TLS was not observed. In p53KO-MEF, which is a strict control for Rev3KO-MEF, the UV-TLS response was similar to that of the wild-type. Introduction of the Rev3 expression plasmid into Rev3KO-MEF restored the UV-TLS response in selected stable transformants. In some transformants, viability to UV was the same as that in the wild-type, and the death rate was increased by caffeine. Our findings indicate that REV3 is predominantly involved in UV-TLS in mouse cells, and that the REV3 translesion pathway is suppressed by caffeine or proteasome inhibitors.
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Affiliation(s)
- Jun Takezawa
- Division of Genetic Biochemistry, The National Institute of Health and Nutrition, Shinjuku-ku, Tokyo 162-8636, Japan; E-Mail: (J.T.)
| | - Naomi Aiba
- Division of Genetic Biochemistry, The National Institute of Health and Nutrition, Shinjuku-ku, Tokyo 162-8636, Japan; E-Mail: (J.T.)
| | - Kagemasa Kajiwara
- School of Medicine, Tokai University, Isehara-shi, Kanagawa-ken 259-1193, Japan
| | - Kouichi Yamada
- Division of Genetic Biochemistry, The National Institute of Health and Nutrition, Shinjuku-ku, Tokyo 162-8636, Japan; E-Mail: (J.T.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +81-3-3203-5723; Fax: +81-3-3203-0335
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24
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Xie P. A nucleotide binding rectification Brownian ratchet model for translocation of Y-family DNA polymerases. Theor Biol Med Model 2011; 8:22. [PMID: 21699732 PMCID: PMC3138451 DOI: 10.1186/1742-4682-8-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 06/24/2011] [Indexed: 02/06/2023] Open
Abstract
Y-family DNA polymerases are characterized by low-fidelity synthesis on undamaged DNA and ability to catalyze translesion synthesis over the damaged DNA. Their translocation along the DNA template is an important event during processive DNA synthesis. In this work we present a Brownian ratchet model for this translocation, where the directed translocation is rectified by the nucleotide binding to the polymerase. Using the model, different features of the available structures for Dpo4, Dbh and polymerase ι in binary and ternary forms can be easily explained. Other dynamic properties of the Y-family polymerases such as the fast translocation event upon dNTP binding for Dpo4 and the considerable variations of the processivity among the polymerases can also be well explained by using the model. In addition, some predicted results of the DNA synthesis rate versus the external force acting on Dpo4 and Dbh polymerases are presented. Moreover, we compare the effect of the external force on the DNA synthesis rate of the Y-family polymerase with that of the replicative DNA polymerase.
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Affiliation(s)
- Ping Xie
- Key Laboratory of Soft Matter Physics and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
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25
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Abstract
REV1 is a Y-family polymerase that plays a central role in mutagenic translesion DNA synthesis (TLS), contributing to tumor initiation and progression. In a current model, a monoubiquitinated form of the replication accessory protein, proliferating cell nuclear antigen (PCNA), serves as a platform to recruit REV1 to damaged sites on the DNA template. Emerging evidence indicates that posttranslational mechanisms regulate REV1 in yeast; however, the regulation of REV1 in higher eukaryotes is poorly understood. Here we show that the molecular chaperone Hsp90 is a critical regulator of REV1 in human cells. Hsp90 specifically binds REV1 in vivo and in vitro. Treatment with a specific inhibitor of Hsp90 reduces REV1 protein levels in several cell types through proteasomal degradation. This is associated with suppression of UV-induced mutagenesis. Furthermore, Hsp90 inhibition disrupts the interaction between REV1 and monoubiquitinated PCNA and suppresses UV-induced focus formation. These results indicate that Hsp90 promotes folding of REV1 into a stable and/or functional form(s) to bind to monoubiquitinated PCNA. The present findings reveal a novel role of Hsp90 in the regulation of TLS-mediated mutagenesis.
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26
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Andersen PL, Xu F, Ziola B, McGregor WG, Xiao W. Sequential assembly of translesion DNA polymerases at UV-induced DNA damage sites. Mol Biol Cell 2011; 22:2373-83. [PMID: 21551069 PMCID: PMC3128538 DOI: 10.1091/mbc.e10-12-0938] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Three endogenous translesion DNA polymerases are sequentially assembled to the stalled
replication site in the form of UV-induced nuclear foci. Detailed supporting evidence is given for the polymerase switch model. In response to DNA damage such as from UV irradiation, mammalian Y-family translesion synthesis (TLS) polymerases Polη and Rev1 colocalize with proliferating cell nuclear antigen at nuclear foci, presumably representing stalled replication sites. However, it is unclear whether the localization of one polymerase is dependent on another. Furthermore, there is no report on the in vivo characterization of the Rev3 catalytic subunit of the B-family TLS polymerase Polζ. Here we describe the detection of endogenous human Polη, Rev1, and Rev3 by immunocytochemistry using existing or newly created antibodies, as well as various means of inhibiting their expression, which allows us to examine the dynamics of endogenous TLS polymerases in response to UV irradiation. It is found that Rev1 and Polη are independently recruited to the nuclear foci, whereas the Rev3 nuclear focus formation requires Rev1 but not Polη. In contrast, neither Rev1 nor Polη recruitment requires Rev3. To further support these conclusions, we find that simultaneous suppression of Polη and Rev3 results in an additive cellular sensitivity to UV irradiation. These observations suggest a cooperative and sequential assembly of TLS polymerases in response to DNA damage. They also support and extend the current polymerase switch model.
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Affiliation(s)
- Parker L Andersen
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, S7N 5E5, Canada
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27
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Abstract
Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage. Two models have been proposed: "error-free" bypass of deaminated cytosine-containing cyclobutane pyrimidine dimers (CPDs) by DNA polymerase η, and error-prone bypass of CPDs and other UV-induced photolesions by combinations of TLS and replicative DNA polymerases--the latter model has also been known as the two-step model, in which the cooperation of two (or more) DNA polymerases as misinserters and (mis)extenders is assumed. Daylight UV induces a characteristic UV-specific mutation, a UV-signature mutation occurring preferentially at methyl-CpG sites, which is also observed frequently after exposure to either UVB or UVA, but not to UVC. The wavelengths relevant to the mutation are so consistent with the composition of daylight UV that the mutation is called solar-UV signature, highlighting the importance of this type of mutation for creatures with the cytosine-methylated genome that are exposed to the sun in the natural environment. UVA has also been suggested to induce oxidative types of mutation, which would be caused by oxidative DNA damage produced through the oxidative stress after the irradiation. Indeed, UVA produces oxidative DNA damage not only in cells but also in skin, which, however, does not seem sufficient to induce mutations in the normal skin genome. In contrast, it has been demonstrated that UVA exclusively induces the solar-UV signature mutations in vivo through CPD formation.
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Affiliation(s)
- Hironobu Ikehata
- Division of Genome and Radiation Biology, Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai, Japan.
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28
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Takezawa J, Ishimi Y, Aiba N, Yamada K. Rev1, Rev3, or Rev7 siRNA Abolishes Ultraviolet Light-Induced Translesion Replication in HeLa Cells: A Comprehensive Study Using Alkaline Sucrose Density Gradient Sedimentation. J Nucleic Acids 2010; 2010:750296. [PMID: 21151666 PMCID: PMC2997509 DOI: 10.4061/2010/750296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/13/2010] [Accepted: 09/17/2010] [Indexed: 01/04/2023] Open
Abstract
When a replicative DNA polymerase stalls upon encountering a lesion on the template strand, it is relieved by other low-processivity polymerase(s), which insert nucleotide(s) opposite the lesion, extend by a few nucleotides, and dissociate from the 3'-OH. The replicative polymerase then resumes DNA synthesis. This process, termed translesion replication (TLS) or replicative bypass, may involve at least five different polymerases in mammals, although the participating polymerases and their roles have not been entirely characterized. Using siRNAs originally designed and an alkaline sucrose density gradient sedimentation technique, we verified the involvement of several polymerases in ultraviolet (UV) light-induced TLS in HeLa cells. First, siRNAs to Rev3 or Rev7 largely abolished UV-TLS, suggesting that these 2 gene products, which comprise Polζ, play a main role in mutagenic TLS. Second, Rev1-targeted siRNA also abrogated UV-TLS, indicating that Rev1 is also indispensable to mutagenic TLS. Third, Polη-targeted siRNA also prevented TLS to a greater extent than our expectations. Forth, although siRNA to Polι had no detectable effect, that to Polκ delayed UV-TLS. To our knowledge, this is the first study reporting apparent evidence for the participation of Polκ in UV-TLS.
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Affiliation(s)
- Jun Takezawa
- Division of Genetic Biochemistry, The National Institute of Health and Nutrition, Shinjuku-ku, Tokyo 162-8636, Japan
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29
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Abstract
The development of cancer drug resistance is a persistent clinical problem limiting the successful treatment of disseminated malignancies. However, the molecular mechanisms by which initially chemoresponsive tumors develop therapeutic resistance remain poorly understood. Error-prone translesional DNA synthesis (TLS) is known to underlie the mutagenic effects of numerous anticancer agents, but little is known as to whether mutation induced by this process is ultimately relevant to tumor drug resistance. Here, we use a tractable mouse model of B-cell lymphoma to interrogate the role of error-prone translesional DNA synthesis in chemotherapy-induced mutation and resistance to front-line chemotherapy. We find that suppression of Rev1, an essential TLS scaffold protein and dCMP transferase, inhibits both cisplatin- and cyclophosphamide-induced mutagenesis. Additionally, by performing repeated cycles of tumor engraftment and treatment, we show that Rev1 plays a critical role in the development of acquired cyclophosphamide resistance. Thus, chemotherapy not only selects for drug-resistant tumor population but also directly promotes the TLS-mediated acquisition of resistance-causing mutations. These data provide an example of an alteration that prevents the acquisition of drug resistance in tumors in vivo. Because TLS also represents a critical mechanism of DNA synthesis in tumor cells following chemotherapy, these data suggest that TLS inhibition may have dual anticancer effects, sensitizing tumors to therapy as well as preventing the emergence of tumor chemoresistance.
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30
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The DNA polymerase activity of Saccharomyces cerevisiae Rev1 is biologically significant. Genetics 2010; 187:21-35. [PMID: 20980236 DOI: 10.1534/genetics.110.124172] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
A cell's ability to tolerate DNA damage is directly connected to the human development of diseases and cancer. To better understand the processes underlying mutagenesis, we studied the cell's reliance on the potentially error-prone translesion synthesis (TLS), and an error-free, template-switching pathway in Saccharomyces cerevisiae. The primary proteins mediating S. cerevisiae TLS are three DNA polymerases (Pols): Rev1, Pol ζ (Rev3/7), and Pol η (Rad30), all with human homologs. Rev1's noncatalytic role in recruiting other DNA polymerases is known to be important for TLS. However, the biological significance of Rev1's unusual conserved DNA polymerase activity, which inserts dC, is much less well understood. Here, we demonstrate that inactivating Rev1's DNA polymerase function sensitizes cells to both chronic and acute exposure to 4-nitroquinoline-1-oxide (4-NQO) but not to UV or cisplatin. Full Rev1-dependent resistance to 4-NQO, however, also requires the additional Rev1 functions. When error-free tolerance is disrupted through deletion of MMS2, Rev1's catalytic activity is more vital for 4-NQO resistance, possibly explaining why the biological significance of Rev1's catalytic activity has been elusive. In the presence or absence of Mms2-dependent error-free tolerance, the catalytic dead strain of Rev1 exhibits a lower 4-NQO-induced mutation frequency than wild type. Furthermore, Pol ζ, but not Pol η, also contributes to 4-NQO resistance. These results show that Rev1's catalytic activity is important in vivo when the cell has to cope with specific DNA lesions, such as N(2)-dG.
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31
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Stallons LJ, McGregor WG. Translesion synthesis polymerases in the prevention and promotion of carcinogenesis. J Nucleic Acids 2010; 2010. [PMID: 20936171 PMCID: PMC2945679 DOI: 10.4061/2010/643857] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 08/13/2010] [Indexed: 12/29/2022] Open
Abstract
A critical step in the transformation of cells to the malignant state of cancer is the induction of mutations in the DNA of cells damaged by genotoxic agents. Translesion DNA synthesis (TLS) is the process by which cells copy DNA containing unrepaired damage that blocks progression of the replication fork. The DNA polymerases that catalyze TLS in mammals have been the topic of intense investigation over the last decade. DNA polymerase η (Pol η) is best understood and is active in error-free bypass of UV-induced DNA damage. The other TLS polymerases (Pol ι, Pol κ, REV1, and Pol ζ) have been studied extensively in vitro, but their in vivo role is only now being investigated using knockout mouse models of carcinogenesis. This paper will focus on the studies of mice and humans with altered expression of TLS polymerases and the effects on cancer induced by environmental agents.
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Affiliation(s)
- L Jay Stallons
- Department of Pharmacology and Toxicology, James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY 40202, USA
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32
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Zhou Y, Wang J, Zhang Y, Wang Z. The catalytic function of the Rev1 dCMP transferase is required in a lesion-specific manner for translesion synthesis and base damage-induced mutagenesis. Nucleic Acids Res 2010; 38:5036-46. [PMID: 20388628 PMCID: PMC2926598 DOI: 10.1093/nar/gkq225] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The Rev1-Polzeta pathway is believed to be the major mechanism of translesion DNA synthesis and base damage-induced mutagenesis in eukaryotes. While it is widely believed that Rev1 plays a non-catalytic function in translesion synthesis, the role of its dCMP transferase activity remains uncertain. To determine the relevance of its catalytic function in translesion synthesis, we separated the Rev1 dCMP transferase activity from its non-catalytic function in yeast. This was achieved by mutating two conserved amino acid residues in the catalytic domain of Rev1, i.e. D467A/E468A, where its catalytic function was abolished but its non-catalytic function remained intact. In this mutant strain, whereas translesion synthesis and mutagenesis of UV radiation were fully functional, those of a site-specific 1,N(6)-ethenoadenine were severely deficient. Specifically, the predominant A-->G mutations resulting from C insertion opposite the lesion were abolished. Therefore, translesion synthesis and mutagenesis of 1,N(6)-ethenoadenine require the catalytic function of the Rev1 dCMP transferase, in contrast to those of UV lesions, which only require the non-catalytic function of Rev1. These results show that the catalytic function of the Rev1 dCMP transferase is required in a lesion-specific manner for translesion synthesis and base damage-induced mutagenesis.
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Affiliation(s)
- Ying Zhou
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
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33
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Separate roles of structured and unstructured regions of Y-family DNA polymerases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2009; 78:99-146. [PMID: 20663485 DOI: 10.1016/s1876-1623(08)78004-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
All organisms have multiple DNA polymerases specialized for translesion DNA synthesis (TLS) on damaged DNA templates. Mammalian TLS DNA polymerases include Pol eta, Pol iota, Pol kappa, and Rev1 (all classified as "Y-family" members) and Pol zeta (a "B-family" member). Y-family DNA polymerases have highly structured catalytic domains; however, some of these proteins adopt different structures when bound to DNA (such as archaeal Dpo4 and human Pol kappa), while others maintain similar structures independently of DNA binding (such as archaeal Dbh and Saccharomyces cerevisiae Pol eta). DNA binding-induced structural conversions of TLS polymerases depend on flexible regions present within the catalytic domains. In contrast, noncatalytic regions of Y-family proteins, which contain multiple domains and motifs for interactions with other proteins, are predicted to be mostly unstructured, except for short regions corresponding to ubiquitin-binding domains. In this review we discuss how the organization of structured and unstructured regions in TLS polymerases is relevant to their regulation and function during lesion bypass.
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34
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Kaufmann WK. The human intra-S checkpoint response to UVC-induced DNA damage. Carcinogenesis 2009; 31:751-65. [PMID: 19793801 DOI: 10.1093/carcin/bgp230] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The intra-S checkpoint response to 254 nm light (UVC)-induced DNA damage appears to have dual functions to slow the rate of DNA synthesis and stabilize replication forks that become stalled at sites of UVC-induced photoproducts in DNA. These functions should provide more time for repair of damaged DNA before its replication and thereby reduce the frequencies of mutations and chromosomal aberrations in surviving cells. This review tries to summarize the history of discovery of the checkpoint, the current state of understanding of the biological features of intra-S checkpoint signaling and its mechanisms of action with a focus primarily on intra-S checkpoint responses in human cells. The differences in the intra-S checkpoint responses to UVC and ionizing radiation-induced DNA damage are emphasized. Evidence that [6-4]pyrimidine-pyrimidone photoproducts in DNA trigger the response is discussed and the relationships between cellular responses to UVC and the molecular dose of UVC-induced DNA damage are briefly summarized. The role of the intra-S checkpoint response in protecting against solar radiation carcinogenesis remains to be determined.
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Affiliation(s)
- William K Kaufmann
- Department of Pathology and Laboratory Medicine, Center for Environmental Health and Susceptibility, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA.
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35
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Madia F, Wei M, Yuan V, Hu J, Gattazzo C, Pham P, Goodman MF, Longo VD. Oncogene homologue Sch9 promotes age-dependent mutations by a superoxide and Rev1/Polzeta-dependent mechanism. ACTA ACUST UNITED AC 2009; 186:509-23. [PMID: 19687253 PMCID: PMC2733759 DOI: 10.1083/jcb.200906011] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Oncogenes contribute to tumorigenesis by promoting growth and inhibiting apoptosis. Here we examine the function of Sch9, the Saccharomyces cerevisiae homologue of the mammalian Akt and S6 kinase, in DNA damage and genomic instability during aging in nondividing cells. Attenuation of age-dependent increases in base substitutions, small DNA insertions/deletions, and gross chromosomal rearrangements (GCRs) in sch9Δ mutants is associated with increased mitochondrial superoxide dismutase (MnSOD) expression, decreased DNA oxidation, reduced REV1 expression and translesion synthesis, and elevated resistance to oxidative stress-induced mutagenesis. Deletion of REV1, the lack of components of the error-prone Polζ, or the overexpression of SOD1 or SOD2 is sufficient to reduce age-dependent point mutations in SCH9 overexpressors, but REV1 deficiency causes a major increase in GCRs. These results suggest that the proto-oncogene homologue Sch9 promotes the accumulation of superoxide-dependent DNA damage in nondividing cells, which induces error-prone DNA repair that generates point mutations to avoid GCRs and cell death during the first round of replication.
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Affiliation(s)
- Federica Madia
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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36
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Guo C, Kosarek-Stancel JN, Tang TS, Friedberg EC. Y-family DNA polymerases in mammalian cells. Cell Mol Life Sci 2009; 66:2363-81. [PMID: 19367366 PMCID: PMC11115694 DOI: 10.1007/s00018-009-0024-4] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 03/05/2009] [Accepted: 03/23/2009] [Indexed: 11/26/2022]
Abstract
Eukaryotic genomes are replicated with high fidelity to assure the faithful transmission of genetic information from one generation to the next. The accuracy of replication relies heavily on the ability of replicative DNA polymerases to efficiently select correct nucleotides for the polymerization reaction and, using their intrinsic exonuclease activities, to excise mistakenly incorporated nucleotides. Cells also possess a variety of specialized DNA polymerases that, by a process called translesion DNA synthesis (TLS), help overcome replication blocks when unrepaired DNA lesions stall the replication machinery. This review considers the properties of the Y-family (a subset of specialized DNA polymerases) and their roles in modulating spontaneous and genotoxic-induced mutations in mammals. We also review recent insights into the molecular mechanisms that regulate PCNA monoubiquitination and DNA polymerase switching during TLS and discuss the potential of using Y-family DNA polymerases as novel targets for cancer prevention and therapy.
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Affiliation(s)
- Caixia Guo
- Laboratory of Molecular Pathology, Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9072, USA.
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37
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Chen B, Simpson DA, Zhou Y, Mitra A, Mitchell DL, Cordeiro-Stone M, Kaufmann WK. Human papilloma virus type16 E6 deregulates CHK1 and sensitizes human fibroblasts to environmental carcinogens independently of its effect on p53. Cell Cycle 2009; 8:1775-87. [PMID: 19411857 DOI: 10.4161/cc.8.11.8724] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
After treatment with ultraviolet radiation (UV), human fibroblasts that express the HPV type 16 E6 oncoprotein display defects in repair of cyclobutane pyrimidine dimers, hypersensitivity to inactivation of clonogenic survival and an inability to sustain DNA replication. To determine whether these effects are specific to depletion of p53 or inactivation of its function, fibroblast lines were constructed with ectopic expression of a dominant-negative p53 allele (p53-H179Q) to inactivate function or a short-hairpin RNA (p53-RNAi) to deplete expression of p53. Only the expression of HPV16E6 sensitized fibroblasts to UV or the chemical carcinogen, benzo[a]pyrene diolepoxide I (BPDE). Carcinogen-treated cells expressing p53-H179Q or p53-RNAi were resistant to inactivation of colony formation and did not suffer replication arrest. CHK1 is a key checkpoint kinase in the response to carcinogen-induced DNA damage. Control and p53-RNAi-expressing fibroblasts displayed phosphorylation of Ser345 on CHK1 45-120 min after carcinogen treatment with a return to near baseline phosphorylation by 6 h after treatment. HPV16E6-expressing fibroblasts displayed enhanced and sustained phosphorylation of CHK1. This was associated with enhanced phosphorylation of Thr68 on CHK2 and Ser139 on H2AX, both markers of severe replication stress and DNA double strand breaks. Incubation with the phosphatase inhibitor okadaic acid produced more phosphorylation of CHK1 in UV-treated HPV16E6-expressing cells than in p53-H179Q-expressing cells suggesting that HPV16E6 may interfere with the recovery of coupled DNA replication at replication forks that are stalled at [6-4]pyrimidine-pyrimidone photoproducts and BPDE-DNA adducts. The results indicate that HPV16E6 targets a protein or proteins other than p53 to deregulate the activity of CHK1 in carcinogen-damaged cells.
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Affiliation(s)
- Bo Chen
- Department of Nutrition Health and Food Safety, School of Public Health, Fudan University, Shanghai, China
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38
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Akagi JI, Masutani C, Kataoka Y, Kan T, Ohashi E, Mori T, Ohmori H, Hanaoka F. Interaction with DNA polymerase η is required for nuclear accumulation of REV1 and suppression of spontaneous mutations in human cells. DNA Repair (Amst) 2009; 8:585-99. [DOI: 10.1016/j.dnarep.2008.12.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 11/27/2008] [Accepted: 12/09/2008] [Indexed: 01/26/2023]
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39
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Waters LS, Minesinger BK, Wiltrout ME, D'Souza S, Woodruff RV, Walker GC. Eukaryotic translesion polymerases and their roles and regulation in DNA damage tolerance. Microbiol Mol Biol Rev 2009; 73:134-54. [PMID: 19258535 PMCID: PMC2650891 DOI: 10.1128/mmbr.00034-08] [Citation(s) in RCA: 440] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
DNA repair and DNA damage tolerance machineries are crucial to overcome the vast array of DNA damage that a cell encounters during its lifetime. In this review, we summarize the current state of knowledge about the eukaryotic DNA damage tolerance pathway translesion synthesis (TLS), a process in which specialized DNA polymerases replicate across from DNA lesions. TLS aids in resistance to DNA damage, presumably by restarting stalled replication forks or filling in gaps that remain in the genome due to the presence of DNA lesions. One consequence of this process is the potential risk of introducing mutations. Given the role of these translesion polymerases in mutagenesis, we discuss the significant regulatory mechanisms that control the five known eukaryotic translesion polymerases: Rev1, Pol zeta, Pol kappa, Pol eta, and Pol iota.
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Affiliation(s)
- Lauren S Waters
- Department of Biology, Massachusetts Institute of Technology, Building 68, Room 653, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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40
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Dumstorf CA, Mukhopadhyay S, Krishnan E, Haribabu B, McGregor WG. REV1 is implicated in the development of carcinogen-induced lung cancer. Mol Cancer Res 2009; 7:247-54. [PMID: 19176310 DOI: 10.1158/1541-7786.mcr-08-0399] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The somatic mutation hypothesis of cancer predicts that reducing the frequency of mutations induced by carcinogens will reduce the incidence of cancer. To examine this, we developed an antimutator strategy based on the manipulation of the level of a protein required for mutagenic bypass of DNA damage induced by the ubiquitous carcinogen benzo[a]pyrene. The expression of this protein, REV1, was reduced in mouse cells using a vector encoding a gene-specific targeting ribozyme. In the latter cells, mutagenesis induced by the activated form of benzo[a]pyrene was reduced by >90%. To examine if REV1 transcripts could be lowered in vivo, the plasmid was complexed with polyethyleneimine, a nonviral cationic polymer, and delivered to the lung via aerosol. The endogenous REV1 transcript in the bronchial epithelium as determined by quantitative real-time PCR in laser capture microdissected cells was reduced by 60%. There was a significant decrease in the multiplicity of carcinogen-induced lung tumors from 6.4 to 3.7 tumors per mouse. Additionally, REV1 inhibition completely abolished tumor formation in 27% of the carcinogen-exposed mice. These data support the central role of the translesion synthesis pathway in the development of lung cancer. Further, the selective modulation of members of this pathway presents novel potential targets for cancer prevention. The somatic mutation hypothesis of cancer predicts that the frequency of cancers will also be reduced.
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Affiliation(s)
- Chad A Dumstorf
- Department of Pharmacology, University of Louisville, Louisville, KY 40202, USA
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41
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Watson NB, Nelson E, Digman M, Thornburg JA, Alphenaar BW, McGregor WG. RAD18 and associated proteins are immobilized in nuclear foci in human cells entering S-phase with ultraviolet light-induced damage. Mutat Res 2008; 648:23-31. [PMID: 18926833 PMCID: PMC2610409 DOI: 10.1016/j.mrfmmm.2008.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 09/09/2008] [Accepted: 09/10/2008] [Indexed: 05/26/2023]
Abstract
Proteins required for translesion DNA synthesis localize in nuclear foci of cells with replication-blocking lesions. The dynamics of this process were examined in human cells with fluorescence-based biophysical techniques. Photobleaching recovery and raster image correlation spectroscopy experiments indicated that involvement in the nuclear foci reduced the movement of RAD18 from diffusion-controlled to virtual immobility. Examination of the mobility of REV1 indicated that it is similarly immobilized when it is observed in nuclear foci. Reducing the level of RAD18 greatly reduced the focal accumulation of REV1 and reduced UV mutagenesis to background frequencies. Fluorescence lifetime measurements indicated that RAD18 and RAD6A or poleta only transferred resonance energy when these proteins colocalized in damage-induced nuclear foci, indicating a close physical association only within such foci. Our data support a model in which RAD18 within damage-induced nuclear foci is immobilized and is required for recruitment of Y-family DNA polymerases and subsequent mutagenesis. In the absence of damage these proteins are not physically associated within the nucleoplasm.
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Affiliation(s)
- Nicholas B. Watson
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202
| | - Eric Nelson
- Department of Computer and Electrical Engineering, University of Louisville, Louisville, KY 40202
| | - Michelle Digman
- Laboratory for Fluorescence Dynamics, University of California, Irvine, CA 92697
| | - Joshua A. Thornburg
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202
| | - Bruce W. Alphenaar
- Department of Computer and Electrical Engineering, University of Louisville, Louisville, KY 40202
| | - W. Glenn McGregor
- Department of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202
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42
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D'Souza S, Waters LS, Walker GC. Novel conserved motifs in Rev1 C-terminus are required for mutagenic DNA damage tolerance. DNA Repair (Amst) 2008; 7:1455-70. [PMID: 18603483 DOI: 10.1016/j.dnarep.2008.05.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 05/02/2008] [Accepted: 05/08/2008] [Indexed: 01/28/2023]
Abstract
The genes encoding Rev1 and DNA polymerase zeta (Rev3/Rev7) are together required for the vast majority of DNA damage-induced mutations in eukaryotes from yeast to humans. Here, we provide insight into the critical role that the Saccharomyces cerevisiae Rev1 C-terminus plays in the process of mutagenic DNA damage tolerance. The Rev1 C-terminus was previously thought to be poorly conserved and therefore not likely to be important for mediating protein-protein interactions. However, through comprehensive alignments of the Rev1 C-terminus, we have identified novel and hitherto unrecognized conserved motifs that we show play an essential role in REV1-dependent survival and mutagenesis in S. cerevisiae, likely in its post-replicative gap-filling mode. We further show that the minimal C-terminal fragment of Rev1 containing these highly conserved motifs is sufficient to interact with Rev7.
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Affiliation(s)
- Sanjay D'Souza
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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43
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Mirchandani KD, McCaffrey RM, D'Andrea AD. The Fanconi anemia core complex is required for efficient point mutagenesis and Rev1 foci assembly. DNA Repair (Amst) 2008; 7:902-11. [PMID: 18448394 DOI: 10.1016/j.dnarep.2008.03.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 02/28/2008] [Accepted: 03/03/2008] [Indexed: 11/28/2022]
Abstract
Fanconi anemia (FA) is a chromosome instability syndrome characterized by congenital abnormalities, cellular hypersensitivity to DNA crosslinking agents, and heightened cancer risk. Eight of the thirteen identified FA genes encode subunits of a nuclear FA core complex that monoubiquitinates FANCD2 and FANCI to maintain genomic stability in response to replication stress. The FA pathway has been implicated in the regulation of error-prone DNA damage tolerance via an undefined molecular mechanism. Here, we show that the FA core complex is required for efficient spontaneous and UVC-induced point mutagenesis, independently of FANCD2 and FANCI. Consistent with the observed hypomutability of cells deficient in the FA core complex, we also demonstrate that these cells are impaired in the assembly of the error-prone translesion DNA synthesis polymerase Rev1 into nuclear foci. Consistent with a role downstream of the FA core complex and like known FA proteins, Rev1 is required to prevent DNA crosslinker-induced chromosomal aberrations in human cells. Interestingly, proliferating cell nuclear antigen (PCNA) monoubiquitination, known to contribute to Rev1 recruitment, does not require FA core complex function. Our results suggest a role for the FA core complex in regulating Rev1-dependent DNA damage tolerance independently of FANCD2, FANCI, and PCNA monoubiquitination.
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Affiliation(s)
- Kanchan D Mirchandani
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
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44
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Nikolaishvili-Feinberg N, Jenkins GS, Nevis KR, Staus DP, Scarlett CO, Unsal-Kaçmaz K, Kaufmann WK, Cordeiro-Stone M. Ubiquitylation of proliferating cell nuclear antigen and recruitment of human DNA polymerase eta. Biochemistry 2008; 47:4141-50. [PMID: 18321066 DOI: 10.1021/bi702329h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This study investigated the requirement for ubiquitylation of PCNA at lysine 164 during polymerase eta-dependent translesion synthesis (TLS) of site-specific cis-syn cyclobutane thymine dimers (T (wedge)T). The in vitro assay recapitulated origin-dependent initiation, fork assembly, and semiconservative, bidirectional replication of double-stranded circular DNA substrates. A phosphocellulose column was used to fractionate HeLa cell extracts into two fractions; flow-through column fraction I (CFI) contained endogenous PCNA, RPA, ubiquitin-activating enzyme E1, and ubiquitin conjugase Rad6, and eluted column fraction II (CFII) included pol delta, pol eta, and RFC. CFII supplemented with purified recombinant RPA and PCNA (wild type or K164R, in which lysine was replaced with arginine) was competent for DNA replication and TLS. K164R-PCNA complemented CFII for these activities to the same extent and efficiency as wild-type PCNA. CFII mixed with CFI (endogenous PCNA, E1, Rad6) exhibited enhanced DNA replication activity, but the same TLS efficiency determined with the purified proteins. These results demonstrate that PCNA ubiquitylation at K164 of PCNA is not required in vitro for pol eta to gain access to replication complexes at forks stalled by T (wedge)T and to catalyze TLS across this dimer.
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Affiliation(s)
- Nana Nikolaishvili-Feinberg
- Department of Pathology and Laboratory Medicine, Lineberger Comprehensive Cancer Center and Center for Environmental Health and Susceptibility, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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45
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Eukaryotic DNA damage tolerance and translesion synthesis through covalent modifications of PCNA. Cell Res 2008; 18:162-73. [PMID: 18157158 DOI: 10.1038/cr.2007.114] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In addition to well-defined DNA repair pathways, all living organisms have evolved mechanisms to avoid cell death caused by replication fork collapse at a site where replication is blocked due to disruptive covalent modifications of DNA. The term DNA damage tolerance (DDT) has been employed loosely to include a collection of mechanisms by which cells survive replication-blocking lesions with or without associated genomic instability. Recent genetic analyses indicate that DDT in eukaryotes, from yeast to human, consists of two parallel pathways with one being error-free and another highly mutagenic. Interestingly, in budding yeast, these two pathways are mediated by sequential modifications of the proliferating cell nuclear antigen (PCNA) by two ubiquitination complexes Rad6-Rad18 and Mms2-Ubc13-Rad5. Damage-induced monoubiquitination of PCNA by Rad6-Rad18 promotes translesion synthesis (TLS) with increased mutagenesis, while subsequent polyubiquitination of PCNA at the same K164 residue by Mms2-Ubc13-Rad5 promotes error-free lesion bypass. Data obtained from recent studies suggest that the above mechanisms are conserved in higher eukaryotes. In particular, mammals contain multiple specialized TLS polymerases. Defects in one of the TLS polymerases have been linked to genomic instability and cancer.
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46
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Gan GN, Wittschieben JP, Wittschieben BØ, Wood RD. DNA polymerase zeta (pol zeta) in higher eukaryotes. Cell Res 2008; 18:174-83. [PMID: 18157155 DOI: 10.1038/cr.2007.117] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Most current knowledge about DNA polymerase zeta (pol zeta) comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where pol zeta consists of a complex of the catalytic subunit Rev3 with Rev7, which associates with Rev1. Most spontaneous and induced mutagenesis in yeast is dependent on these gene products, and yeast pol zeta can mediate translesion DNA synthesis past some adducts in DNA templates. Study of the homologous gene products in higher eukaryotes is in a relatively early stage, but additional functions for the eukaryotic proteins are already apparent. Suppression of vertebrate REV3L function not only reduces induced point mutagenesis but also causes larger-scale genome instability by raising the frequency of spontaneous chromosome translocations. Disruption of Rev3L function is tolerated in Drosophila, Arabidopsis, and in vertebrate cell lines under some conditions, but is incompatible with mouse embryonic development. Functions for REV3L and REV7(MAD2B) in higher eukaryotes have been suggested not only in translesion DNA synthesis but also in some forms of homologous recombination, repair of interstrand DNA crosslinks, somatic hypermutation of immunoglobulin genes and cell-cycle control. This review discusses recent developments in these areas.
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Affiliation(s)
- Gregory N Gan
- Department of Pharmacology, University of Pittsburgh Medical School, Pittsburgh, PA 15213, USA
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Yoshihara R, Nakane C, Sato R, Yasuda A, Takimoto K. Silencing of CPD Photolyase Makes Arabidopsis Hypersensitive and Hypermutable in Response to UV-B Radiation. Genes Environ 2008. [DOI: 10.3123/jemsge.30.53] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Ikehata H, Ono T, Tanaka K, Todo T. A model for triplet mutation formation based on error-prone translesional DNA synthesis opposite UV photolesions. DNA Repair (Amst) 2007; 6:658-68. [PMID: 17275422 DOI: 10.1016/j.dnarep.2006.12.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 12/14/2006] [Accepted: 12/14/2006] [Indexed: 11/23/2022]
Abstract
A triplet mutation is defined as multiple base substitutions or frameshifts within a three-nucleotide sequence which includes a dipyrimidine sequence. Triplet mutations have recently been identified as a new type of UV-specific mutation, although the mechanism of their formation is unknown. A total of 163 triplet mutations were identified through an extensive search of previously published data on UV-induced mutations, including mutations from skin, skin cancer, and cultured mammalian cells. Seven common patterns of sequence changes were found: Type I, NTC-->TTT; Type IIa, NCC-->PyTT or PyCT (Py, pyrimidine); Type IIb, TCC-->PuTT or PuCT (Pu, purine); Type III, NCC-->NAT or NTA; Type IV, NTT-->AAT; Type Va, NCT-->NTX; and Type Vb, PuCT-->XTT (N and X, independent anonymous bases). Furthermore, it is suggested that the type of UV lesion responsible for each of these triplet mutation classes are (a) pyrimidine(6-4)pyrimidone photoproducts for Types I, IIb, III, IV and Vb, (b) cyclobutane pyrimidine dimers for Type Va, and (c) Dewar valence isomers for Types IIa and IIb. These estimations are based primarily on results from previous studies using photolyases specific for each type of UV lesion. A model is proposed to explain the formation of each type of triplet mutation, based on error-prone translesional DNA synthesis opposite UV-specific photolesions. The model is largely consistent with the 'A-rule', and predicts error-prone insertions not only opposite photolesions but also opposite the undamaged template base one-nucleotide downstream from the lesions.
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Affiliation(s)
- Hironobu Ikehata
- Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan.
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Garcia-Diaz M, Bebenek K. Multiple functions of DNA polymerases. CRITICAL REVIEWS IN PLANT SCIENCES 2007; 26:105-122. [PMID: 18496613 PMCID: PMC2391090 DOI: 10.1080/07352680701252817] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The primary role of DNA polymerases is to accurately and efficiently replicate the genome in order to ensure the maintenance of the genetic information and its faithful transmission through generations. This is not a simple task considering the size of the genome and its constant exposure to endogenous and environmental DNA damaging agents. Thus, a number of DNA repair pathways operate in cells to protect the integrity of the genome. In addition to their role in replication, DNA polymerases play a central role in most of these pathways. Given the multitude and the complexity of DNA transactions that depend on DNA polymerase activity, it is not surprising that cells in all organisms contain multiple highly specialized DNA polymerases, the majority of which have only recently been discovered. Five DNA polymerases are now recognized in Escherichia coli, 8 in Saccharomyces cerevisiae, and at least 15 in humans. While polymerases in bacteria, yeast and mammalian cells have been extensively studied much less is known about their counterparts in plants. For example, the plant model organism Arabidopsis thaliana is thought to contain 12 DNA polymerases, whose functions are mostly unknown. Here we review the properties and functions of DNA polymerases focusing on yeast and mammalian cells but paying special attention to the plant enzymes and the special circumstances of replication and repair in plant cells.
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Affiliation(s)
- Miguel Garcia-Diaz
- Laboratory of Structural Biology and Laboratory of Molecular Genetics NIEHS, NIH, DHHS, Research Triangle Park, North Carolina 27709
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Abstract
Errol Friedberg suggested that I write a biographical account of the work carried out in my lab for the Historical Reflections section of the DNA Repair. Although I started out studying meiotic recombination, I have spent much of the last four and a half decades focused on trying to understand the mechanism underlying induced mutagenesis, which led me into what was eventually called DNA damage tolerance, the process that facilitates the resumption of replication when replicases are stalled at sites of DNA template damage. The following account highlights some of our work that contributed to an understanding of the mechanisms underlying these activities, carried out by the RAD6 pathway, my main preoccupation over this period.
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Affiliation(s)
- Christopher W Lawrence
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 602 Elmwood Avenue, Rochester, NY 14642, United States.
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