251
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Pavlov YI, Shcherbakova PV, Rogozin IB. Roles of DNA Polymerases in Replication, Repair, and Recombination in Eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 255:41-132. [PMID: 17178465 DOI: 10.1016/s0074-7696(06)55002-8] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The functioning of the eukaryotic genome depends on efficient and accurate DNA replication and repair. The process of replication is complicated by the ongoing decomposition of DNA and damage of the genome by endogenous and exogenous factors. DNA damage can alter base coding potential resulting in mutations, or block DNA replication, which can lead to double-strand breaks (DSB) and to subsequent chromosome loss. Replication is coordinated with DNA repair systems that operate in cells to remove or tolerate DNA lesions. DNA polymerases can serve as sensors in the cell cycle checkpoint pathways that delay cell division until damaged DNA is repaired and replication is completed. Eukaryotic DNA template-dependent DNA polymerases have different properties adapted to perform an amazingly wide spectrum of DNA transactions. In this review, we discuss the structure, the mechanism, and the evolutionary relationships of DNA polymerases and their possible functions in the replication of intact and damaged chromosomes, DNA damage repair, and recombination.
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Affiliation(s)
- Youri I Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, Departments of Biochemistry and Molecular Biology, and Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA
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252
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Sobeck A, Stone S, Costanzo V, de Graaf B, Reuter T, de Winter J, Wallisch M, Akkari Y, Olson S, Wang W, Joenje H, Christian JL, Lupardus PJ, Cimprich KA, Gautier J, Hoatlin ME. Fanconi anemia proteins are required to prevent accumulation of replication-associated DNA double-strand breaks. Mol Cell Biol 2006; 26:425-37. [PMID: 16382135 PMCID: PMC1346898 DOI: 10.1128/mcb.26.2.425-437.2006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Revised: 07/20/2005] [Accepted: 10/13/2005] [Indexed: 12/19/2022] Open
Abstract
Fanconi anemia (FA) is a multigene cancer susceptibility disorder characterized by cellular hypersensitivity to DNA interstrand cross-linking agents such as mitomycin C (MMC). FA proteins are suspected to function at the interface between cell cycle checkpoints, DNA repair, and DNA replication. Using replicating extracts from Xenopus eggs, we developed cell-free assays for FA proteins (xFA). Recruitment of the xFA core complex and xFANCD2 to chromatin is strictly dependent on replication initiation, even in the presence of MMC indicating specific recruitment to DNA lesions encountered by the replication machinery. The increase in xFA chromatin binding following treatment with MMC is part of a caffeine-sensitive S-phase checkpoint that is controlled by xATR. Recruitment of xFANCD2, but not xFANCA, is dependent on the xATR-xATR-interacting protein (xATRIP) complex. Immunodepletion of either xFANCA or xFANCD2 from egg extracts results in accumulation of chromosomal DNA breaks during replicative synthesis. Our results suggest coordinated chromatin recruitment of xFA proteins in response to replication-associated DNA lesions and indicate that xFA proteins function to prevent the accumulation of DNA breaks that arise during unperturbed replication.
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Affiliation(s)
- Alexandra Sobeck
- Division of Biochemistry and Molecular Biology, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, Oregon 97239, USA
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253
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Abstract
Fanconi anemia is characterized by hypersensitivity to DNA interstrand crosslinks (ICLs) and susceptibility to tumor formation. Despite the identification of numerous Fanconi anemia (FANC) genes, the mechanism by which proteins encoded by these genes protect a cell from DNA interstrand crosslinks remains unclear. The recent discovery of two DNA helicases that, when defective, cause Fanconi anemia tips the balance in favor of the direct involvement of the FANC proteins in DNA repair and the bypass of DNA lesions.
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Affiliation(s)
- Laura J Niedernhofer
- Center for Biomedical Genetics, Medical Genetic Center, Department of Cell Biology and Genetics, Erasmus Medical Center, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
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254
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Abstract
Living organisms are constantly exposed to detrimental agents both from the environment (e.g. ionizing radiation, ultraviolet light, natural and synthetic chemicals) and from endogenous metabolic processes (e.g. oxidative and hydrolytic reactions), resulting in modifications of proteins, lipids and DNA. Proteins and lipids are degraded and resynthesized, but the DNA is replicated only during cell division, when DNA damage may result in mutation fixation. Thus the DNA damage generated has the potential to lead to carcinogenesis, cell death, or other genetic disorders in the absence of efficient error-free repair. Because modifications in DNA sequence or structure may be incompatible with its essential role in preservation and transmission of genetic information from generation to generation, exquisitely sensitive DNA repair pathways have evolved to maintain genomic stability and cell viability. This review focuses on the repair and processing of genome destabilizing lesions and helical distortions that differ significantly from the canonical B-form DNA in mammalian cells. In particular, we discuss the introduction and processing of site-specific lesions in mammalian cells with an emphasis on psoralen interstrand crosslinks.
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Affiliation(s)
- Madhava C Reddy
- Department of Carcinogenesis, The University of Texas M. D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
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255
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Wachters FM, Wong LSM, Timens W, Kampinga HH, Groen HJM. ERCC1, hRad51, and BRCA1 protein expression in relation to tumour response and survival of stage III/IV NSCLC patients treated with chemotherapy. Lung Cancer 2005; 50:211-9. [PMID: 16169122 DOI: 10.1016/j.lungcan.2005.06.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 06/06/2005] [Accepted: 06/06/2005] [Indexed: 11/25/2022]
Abstract
Aim of this explorative study was to determine the prognostic value of protein expression of the DNA damage repair enzymes ERCC1, hRad51, and BRCA1 for tumour response and survival of non-small-cell lung cancer patients treated with chemotherapy. Patients with either a short or long overall survival were selected from a randomized phase III trial comparing cisplatin-gemcitabine and epirubicin-gemcitabine. Tumour biopsies were assessed for differences in immunohistochemical staining using antibodies against ERCC1, hRad51, and BRCA1. A total of 33 patients were included. A positive nuclear staining for ERCC1, hRad51, and BRCA1 was observed in 44, 12, and 90% of biopsies, respectively. In large cell carcinoma nuclear hRad51 staining was absent. In five biopsies stained for hRad51 an unexpected membrane-like staining was observed; these biopsies showed no nuclear staining. DNA damage repair protein expressions were not significantly different in responders versus non-responders, or in patients with a short or long overall survival. In conclusion, immunohistochemical staining of ERCC1, hRad51, and BRCA1, in tumour biopsies from non-small-cell lung cancer patients was not predictive for tumour response and survival after chemotherapy.
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Affiliation(s)
- F M Wachters
- Department of Pulmonary Diseases, University Hospital Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands.
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256
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Lee YJ, Park SJ, Ciccone SLM, Kim CR, Lee SH. An
in vivo
analysis of MMC-induced DNA damage and its repair. Carcinogenesis 2005; 27:446-53. [PMID: 16258176 DOI: 10.1093/carcin/bgi254] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mitomycin C (MMC) induces various types of DNA damages that cause significant cytotoxicity to cells. Accordingly, repair of MMC-induced damages involves multiple repair pathways such as nucleotide excision repair, homologous recombination repair and translesion bypass repair pathways. Nonetheless, repair of the MMC-induced DNA damages in mammals have not been fully delineated. In this study, we investigated potential roles for Xeroderma pigmentosum (XP) proteins in the repair of MMC-induced DNA damages using an assay that detects the ssDNA patches generated following treatment with MMC or 8'-methoxy-psoralen (8-MOP) + UVA (ultraviolet light A). Human wild-type cells formed distinctive ssDNA foci following treatment with MMC or 8-MOP + UVA, but not with those inducing alkylation damage, oxidative damage or strand-break damage, suggesting that the foci represent ssDNA patches formed during the crosslink repair. In contrast to wild-type cells, mutant defective in XPE orXPG did not form the ssDNA foci following MMC treatment, while XPF mutant cells showed a significantly delayed response in forming the foci. A positive role for XPG in the repair of MMC-induced DNA damages was further supported by observations that cells treated with MMC induced a tight association of XPG with chromatin, and a targeted inhibition of XPG abolished MMC-induced ssDNA foci formation, rendering cells hypersensitive to MMC. Together, our results suggest that XPG along with XPE and XPF play unique role(s) in the repair of MMC-induced DNA damages.
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Affiliation(s)
- Young-Ju Lee
- Department of Biochemistry and Molecular Biology, Microbiology and Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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257
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Zhang N, Kaur R, Lu X, Shen X, Li L, Legerski RJ. The Pso4 mRNA splicing and DNA repair complex interacts with WRN for processing of DNA interstrand cross-links. J Biol Chem 2005; 280:40559-67. [PMID: 16223718 DOI: 10.1074/jbc.m508453200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA interstrand cross-links (ICLs) are perhaps the most formidable lesion encountered by the cellular DNA repair machinery, and the elucidation of the process by which they are removed in eukaryotic cells has proved a daunting task. In particular, the early stages of adduct recognition and uncoupling of the cross-link have remained elusive principally because genetic studies have not been highly revealing. We have developed a biochemical assay in which processing of a DNA substrate containing a site-specific psoralen ICL can be monitored in vitro. Using this assay we have shown previously that the mismatch repair factor MutSbeta, the nucleotide excision repair heterodimer Ercc1-Xpf, and the replication proteins RPA and PCNA are involved in an early stage of psoralen ICL processing. Here, we report the identification of two additional factors required in the ICL repair process, a previously characterized pre-mRNA splicing complex composed of Pso4/Prp19, Cdc5L, Plrg1, and Spf27 (Pso4 complex), and WRN the protein deficient in Werner syndrome. Analysis of the WRN protein indicates that its DNA helicase function, but not its exonuclease activity, is required for ICL processing in vitro. In addition, we show that WRN and the Pso4 complex interact through a direct physical association between WRN and Cdc5L. A putative model for uncoupling of ICLs in mammalian cells is presented.
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Affiliation(s)
- Nianxiang Zhang
- Department of Molecular Genetics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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258
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Boo LM, Lin HH, Chung V, Zhou B, Louie SG, O'Reilly MA, Yen Y, Ann DK. High mobility group A2 potentiates genotoxic stress in part through the modulation of basal and DNA damage-dependent phosphatidylinositol 3-kinase-related protein kinase activation. Cancer Res 2005; 65:6622-30. [PMID: 16061642 DOI: 10.1158/0008-5472.can-05-0086] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The high mobility group A2 (HMGA2) protein belongs to the architectural transcription factor HMGA family, playing a role in chromosomal organization and transcriptional regulation. We and others have previously reported that ectopic HMGA2 expression is associated with neoplastic transformation and anchorage-independent cell proliferation. Here, we reported a correlation between increased HMGA2 expression and enhanced chemosensitivity towards topoisomerase II inhibitor, doxorubicin, in breast cancer cells. Using cells exhibiting differential HMGA2 expression and small interfering RNA technique, we showed that HMGA2 expression modulates cellular response to the genotoxicity of DNA double-strand breaks. Notably, HMGA2 enhances doxorubicin-elicited cell cycle delay in sub-G1 and G2-M and augments cell cycle dysregulation on cotreatment of doxorubicin and caffeine. We further reported that HMGA2 induces a persistent Ser139 phosphorylation of histone 2A variant X, analogous to the activation by doxorubicin-mediated genotoxic stress. Moreover, this HMGA2-dependent enhancement of cytotoxicity is further extended to other double-strand breaks elicited by cisplatin and X-ray irradiation and is not restricted to one cell type. Together, we postulated that the enhanced cytotoxicity by double-strand breaks in HMGA2-expressing cells is mediated, at least in part, through the signaling pathway of which the physiologic function is to maintain genome integrity. These findings should contribute to a greater understanding of the role of HMGA2 in promoting tumorigenesis and conveying (chemo)sensitivity towards doxorubicin and other related double-strand breaks.
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Affiliation(s)
- Lee Ming Boo
- Department of Molecular Pharmacology and Toxicology, University of Southern California, Los Angeles, California 90033-1049, USA
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259
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Richards S, Liu ST, Majumdar A, Liu JL, Nairn RS, Bernier M, Maher V, Seidman MM. Triplex targeted genomic crosslinks enter separable deletion and base substitution pathways. Nucleic Acids Res 2005; 33:5382-93. [PMID: 16186129 PMCID: PMC1236719 DOI: 10.1093/nar/gki851] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Revised: 09/03/2005] [Accepted: 09/03/2005] [Indexed: 12/02/2022] Open
Abstract
We have synthesized triple helix forming oligonucleotides (TFOs) that target a psoralen (pso) interstrand crosslink to a specific chromosomal site in mammalian cells. Mutagenesis of the targeted crosslinks results in base substitutions and deletions. Identification of the gene products involved in mutation formation is important for developing practical applications of pso-TFOs, and may be informative about the metabolism of other interstrand crosslinks. We have studied mutagenesis of a pso-TFO genomic crosslink in repair proficient and deficient cells. Deficiencies in non homologous end joining and mismatch repair do not influence mutation patterns. In contrast, the frequency of base substitutions is dependent on the activity of ERCC1/XPF and polymerase zeta, but independent of other nucleotide excision repair (NER) or transcription coupled repair (TCR) genes. In NER/TCR deficient cells the frequency of deletions rises, indicating that in wild-type cells NER/TCR functions divert pso-TFO crosslinks from processes that result in deletions. We conclude that targeted pso-TFO crosslinks can enter genetically distinct mutational routes that resolve to base substitutions or deletions.
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Affiliation(s)
- Sally Richards
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health5600 Nathan Shock Dr, Baltimore, MD 21224, USA
- University of Texas, MD Anderson Cancer Center, Department of CarcinogenesisPO Box 389, 1808 Park Road 1C, Smithville, TX 78957, USA
- Laboratory of Clinical Investigation, NIA/NIHBaltimore, MD 21224, USA
- Carcinogenesis Laboratory, Michigan State UniversityEast Lansing, MI 48824, USA
| | - Su-Ting Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health5600 Nathan Shock Dr, Baltimore, MD 21224, USA
- University of Texas, MD Anderson Cancer Center, Department of CarcinogenesisPO Box 389, 1808 Park Road 1C, Smithville, TX 78957, USA
- Laboratory of Clinical Investigation, NIA/NIHBaltimore, MD 21224, USA
- Carcinogenesis Laboratory, Michigan State UniversityEast Lansing, MI 48824, USA
| | - Alokes Majumdar
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health5600 Nathan Shock Dr, Baltimore, MD 21224, USA
- University of Texas, MD Anderson Cancer Center, Department of CarcinogenesisPO Box 389, 1808 Park Road 1C, Smithville, TX 78957, USA
- Laboratory of Clinical Investigation, NIA/NIHBaltimore, MD 21224, USA
- Carcinogenesis Laboratory, Michigan State UniversityEast Lansing, MI 48824, USA
| | - Ji-Lan Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health5600 Nathan Shock Dr, Baltimore, MD 21224, USA
- University of Texas, MD Anderson Cancer Center, Department of CarcinogenesisPO Box 389, 1808 Park Road 1C, Smithville, TX 78957, USA
- Laboratory of Clinical Investigation, NIA/NIHBaltimore, MD 21224, USA
- Carcinogenesis Laboratory, Michigan State UniversityEast Lansing, MI 48824, USA
| | - Rodney S. Nairn
- University of Texas, MD Anderson Cancer Center, Department of CarcinogenesisPO Box 389, 1808 Park Road 1C, Smithville, TX 78957, USA
| | - Michel Bernier
- Laboratory of Clinical Investigation, NIA/NIHBaltimore, MD 21224, USA
| | - Veronica Maher
- Carcinogenesis Laboratory, Michigan State UniversityEast Lansing, MI 48824, USA
| | - Michael M. Seidman
- To whom correspondence should be addressed. Tel: +1 410 558 8565; Fax: +1 410 558 8157;
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260
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Frankenberg-Schwager M, Kirchermeier D, Greif G, Baer K, Becker M, Frankenberg D. Cisplatin-mediated DNA double-strand breaks in replicating but not in quiescent cells of the yeast Saccharomyces cerevisiae. Toxicology 2005; 212:175-84. [PMID: 15950355 DOI: 10.1016/j.tox.2005.04.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 04/26/2005] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
DNA double-strand breaks (DSBs) are formed during the processing of DNA interstrand crosslinks in replicating yeast and Chinese hamster cells exposed to DNA crosslinkers such as psoralen plus UVA or nitrogen mustard. They were also detected in human cells after treatment with photoactivated psoralen or mitomycin C. In contrast, no DSBs were observed after exposure of Chinese hamster cells to cisplatin, another crosslinking agent widely used for the therapy of various cancers, challenging a common role for DSBs in the processing of DNA interstrand crosslinks. Here we report for the first time that cisplatin-mediated DSBs are induced in replicating but not quiescent cells of the yeast Saccharomyces cerevisiae. When the main pathway of repair of DSBs is inhibited, these breaks accumulate in replicating cells. Thus it appears that DNA interstrand crosslinks induced by different crosslinking agents, including cisplatin, are processed yielding DSBs as an intermediate lesion. In stationary cells, however, removal of DNA interstrand crosslinks after cisplatin treatment occurs without the formation of DSBs. These findings point to an altered mode of processing of cisplatin-DNA adducts in replicating versus quiescent cells.
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Affiliation(s)
- Marlis Frankenberg-Schwager
- Universitaet Goettingen, Zentrum Radiologie, Abteilung Nuklearmedizin, Von-Siebold-Str. 3, D-37075 Goettingen, Germany.
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261
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Dendouga N, Gao H, Moechars D, Janicot M, Vialard J, McGowan CH. Disruption of murine Mus81 increases genomic instability and DNA damage sensitivity but does not promote tumorigenesis. Mol Cell Biol 2005; 25:7569-79. [PMID: 16107704 PMCID: PMC1190297 DOI: 10.1128/mcb.25.17.7569-7579.2005] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 06/03/2005] [Accepted: 06/15/2005] [Indexed: 11/20/2022] Open
Abstract
The Mus81-Eme1 endonuclease is implicated in the efficient rescue of broken replication forks in Saccharomyces cerevisiae and Schizosaccharomyces pombe. We have used gene targeting to study the function of the Mus81-Eme1 endonuclease in mammalian cells. Mus81-deficient mice develop normally and are fertile. Surprisingly, embryonic fibroblasts from Mus81(-/-) animals fail to proliferate in vitro. This proliferation defect can be rescued by expression of the papillomavirus E6 protein that promotes degradation of p53. When grown in culture, Mus81(-/-) cells have elevated levels of DNA damage, acquire chromosomal aberrations, and are hypersensitive to agents that generate DNA cross-links. In contrast to the situation in yeast, murine Mus81 is not required for replication restart following camptothecin treatment. Mus81(-/-) mice and cells are hypersensitive to DNA cross-linking agents. Cross-link-induced double-strand break formation is normal in Mus81(-/-) cells, but the resolution of repair intermediates is not. The persistence of Rad51 foci in Mus81(-/-) cells suggests that Mus81 acts at a late step in the repair of cross-link-induced lesions. Despite these defects, Mus81(-/-) mice do not show increased predisposition to lymphoma or any other malignancy in the first year of life.
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Affiliation(s)
- Najoua Dendouga
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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262
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Bagherieh-Najjar MB, de Vries OMH, Hille J, Dijkwel PP. Arabidopsis RecQI4A suppresses homologous recombination and modulates DNA damage responses. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 43:789-98. [PMID: 16146519 DOI: 10.1111/j.1365-313x.2005.02501.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The DNA damage response and DNA recombination are two interrelated mechanisms involved in maintaining the integrity of the genome, but in plants they are poorly understood. RecQ is a family of genes with conserved roles in the regulation of DNA recombination in eukaryotes; there are seven members in Arabidopsis. Here we report on the functional analysis of the Arabidopsis RecQl4A gene. Ectopic expression of Arabidopsis RecQl4A in yeast RecQ-deficient cells suppressed their hypersensitivity to the DNA-damaging drug methyl methanesulfonate (MMS) and enhanced their rate of homologous recombination (HR). Analysis of three recQl4A mutant alleles revealed no obvious developmental defects or telomere deregulation in plants grown under standard growth conditions. Compared with wild-type Arabidopsis, the recQl4A mutant seedlings were found to be hypersensitive to UV light and MMS, and more resistant to mitomycin C. The average frequency of intrachromosomal HR in recQl4A mutant plants was increased 7.5-fold over that observed in wild-type plants. The data reveal roles for Arabidopsis RecQl4A in maintenance of genome stability by modulation of the DNA damage response and suppression of HR.
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Affiliation(s)
- Mohammad B Bagherieh-Najjar
- Molecular Biology of Plants, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
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263
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Jonnalagadda VS, Matsuguchi T, Engelward BP. Interstrand crosslink-induced homologous recombination carries an increased risk of deletions and insertions. DNA Repair (Amst) 2005; 4:594-605. [PMID: 15811631 DOI: 10.1016/j.dnarep.2005.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Accepted: 02/04/2005] [Indexed: 10/25/2022]
Abstract
Homology directed repair (HDR) defends cells against the toxic effects of two-ended double strand breaks (DSBs) and one-ended DSBs that arise when replication progression is inhibited, for example by encounter with DNA lesions such as interstrand crosslinks (ICLs). HDR can occur via various mechanisms, some of which are associated with an increased risk of concurrent sequence rearrangements that can lead to deletions, insertions, translocations and loss of heterozygosity. Here, we compared the risk of HDR-associated sequence rearrangements that occur spontaneously versus in response to exposure to an agent that induces ICLs. We describe the creation of two fluorescence-based direct repeat recombination substrates that have been targeted to the ROSA26 locus of embryonic stem cells, and that detect the major pathways of homologous recombination events, e.g., gene conversions with or without crossing over, repair of broken replication forks, and single strand annealing (SSA). SSA can be distinguished from other pathways by application of a matched pair of site-specifically integrated substrates, one of which allows detection of SSA, and one that does not. We show that SSA is responsible for a significant proportion of spontaneous homologous recombination events at these substrates, suggesting that two-ended DSBs are a common spontaneous recombinogenic lesion. Interestingly, exposure to mitomycin C (an agent that induces ICLs) increases the proportion of HDR events associated with deletions and insertions. Given that many chemotherapeutics induce ICLs, these results have important implications in terms of the risk of chemotherapy-induced deleterious sequence rearrangements that could potentially contribute to secondary tumors.
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Affiliation(s)
- Vidya S Jonnalagadda
- Biological Engineering Division, Massachusetts Institute of Technology, 77 Massachusetts Ave., 56-631, Cambridge, MA 02139, USA
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264
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Schärer OD. DNA interstrand crosslinks: natural and drug-induced DNA adducts that induce unique cellular responses. Chembiochem 2005; 6:27-32. [PMID: 15637664 DOI: 10.1002/cbic.200400287] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Orlando D Schärer
- Institute of Molecular Cancer Research, University of Zürich, August Forel Strasse 7, 8008 Zürich, Switzerland.
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265
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Clingen PH, De Silva IU, McHugh PJ, Ghadessy FJ, Tilby MJ, Thurston DE, Hartley JA. The XPF-ERCC1 endonuclease and homologous recombination contribute to the repair of minor groove DNA interstrand crosslinks in mammalian cells produced by the pyrrolo[2,1-c][1,4]benzodiazepine dimer SJG-136. Nucleic Acids Res 2005; 33:3283-91. [PMID: 15944449 PMCID: PMC1145189 DOI: 10.1093/nar/gki639] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2005] [Accepted: 05/19/2005] [Indexed: 11/25/2022] Open
Abstract
SJG-136, a pyrrolo[2,1-c][1,4]benzodiazepine (PBD) dimer, is a highly efficient interstrand crosslinking agent that reacts with guanine bases in a 5'-GATC-3' sequence in the DNA minor groove. SJG-136 crosslinks form rapidly and persist compared to those produced by conventional crosslinking agents such as nitrogen mustard, melphalan or cisplatin which bind in the DNA major groove. A panel of Chinese hamster ovary (CHO) cells with defined defects in specific DNA repair pathways were exposed to the bi-functional agents SJG-136 and melphalan, and to their mono-functional analogues mmy-SJG and mono-functional melphalan. SJG-136 was >100 times more cytotoxic than melphalan, and the bi-functional agents were much more cytotoxic than their respective mono-functional analogues. Cellular sensitivity of both SJG-136 and melphalan was dependent on the XPF-ERCC1 heterodimer, and homologous recombination repair factors XRCC2 and XRCC3. The relative level of sensitivity of these repair mutant cell lines to SJG-136 was, however, significantly less than with major groove crosslinking agents. In contrast to melphalan, there was no clear correlation between sensitivity to SJG-136 and crosslink unhooking capacity measured using a modified comet assay. Furthermore, repair of SJG-136 crosslinks did not involve the formation of DNA double-strand breaks. SJG-136 cytotoxicity is likely to result from the poor recognition of DNA damage by repair proteins resulting in the slow repair of both mono-adducts and more importantly crosslinks in the minor groove.
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Affiliation(s)
- Peter H. Clingen
- Cancer Research UK Drug–DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, UCL91 Riding House Street, London, W1W 7BS, UK
- Northern Institute for Cancer Research, University of Newcastle Upon Tyne Medical SchoolNewcastle Upon Tyne NE2 4HH, UK
- Cancer Research UK Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London29-39 Brunswick Square, London WC1N 1AX, UK
| | - Inusha U. De Silva
- Cancer Research UK Drug–DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, UCL91 Riding House Street, London, W1W 7BS, UK
- Northern Institute for Cancer Research, University of Newcastle Upon Tyne Medical SchoolNewcastle Upon Tyne NE2 4HH, UK
- Cancer Research UK Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London29-39 Brunswick Square, London WC1N 1AX, UK
| | - Peter J. McHugh
- Cancer Research UK Drug–DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, UCL91 Riding House Street, London, W1W 7BS, UK
- Northern Institute for Cancer Research, University of Newcastle Upon Tyne Medical SchoolNewcastle Upon Tyne NE2 4HH, UK
- Cancer Research UK Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London29-39 Brunswick Square, London WC1N 1AX, UK
| | - Farid J Ghadessy
- Cancer Research UK Drug–DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, UCL91 Riding House Street, London, W1W 7BS, UK
- Northern Institute for Cancer Research, University of Newcastle Upon Tyne Medical SchoolNewcastle Upon Tyne NE2 4HH, UK
- Cancer Research UK Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London29-39 Brunswick Square, London WC1N 1AX, UK
| | - Michael J. Tilby
- Northern Institute for Cancer Research, University of Newcastle Upon Tyne Medical SchoolNewcastle Upon Tyne NE2 4HH, UK
| | - David E. Thurston
- Cancer Research UK Gene Targeted Drug Design Research Group, The School of Pharmacy, University of London29-39 Brunswick Square, London WC1N 1AX, UK
| | - John A. Hartley
- To whom correspondence should be addressed. Tel: +44 20 7679 9299; Fax: +44 20 7436 2956;
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266
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Wu Q, Christensen LA, Legerski RJ, Vasquez KM. Mismatch repair participates in error-free processing of DNA interstrand crosslinks in human cells. EMBO Rep 2005; 6:551-7. [PMID: 15891767 PMCID: PMC1369090 DOI: 10.1038/sj.embor.7400418] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Revised: 03/16/2005] [Accepted: 04/06/2005] [Indexed: 11/09/2022] Open
Abstract
DNA interstrand crosslinks (ICLs) present formidable blocks to DNA metabolic processes and must be repaired for cell survival. ICLs are induced in DNA by intercalating compounds such as the widely used therapeutic agent psoralen. In bacteria, both nucleotide excision repair (NER) and homologous recombination are required for the repair of ICLs. The processing of ICLs in mammalian cells is not clearly understood. However, it is known that processing can occur by NER, which for psoralen ICLs can be an error-generating process conducive to mutagenesis. We show here that another repair pathway, mismatch repair (MMR), is also involved in eliminating psoralen ICLs in human cells. MMR deficiency renders cells hypersensitive to psoralen ICLs without diminishing their mutagenic potential, suggesting that MMR does not contribute to error-generating repair, and that MMR may represent a relatively error-free mechanism for processing these lesions in human cells. Thus, enhancement of MMR relative to NER may reduce the mutagenesis caused by DNA ICLs in humans.
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Affiliation(s)
- Qi Wu
- Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, 1808 Park Road 1-C, Smithville, Texas 78957, USA
| | - Laura A. Christensen
- Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, 1808 Park Road 1-C, Smithville, Texas 78957, USA
| | - Randy J. Legerski
- Department of Molecular Genetics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
| | - Karen M. Vasquez
- Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, 1808 Park Road 1-C, Smithville, Texas 78957, USA
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267
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Aparicio AM, Elkhouiery AB, Quinn DI. The Current and Future Application of Adjuvant Systemic Chemotherapy in Patients with Bladder Cancer Following Cystectomy. Urol Clin North Am 2005; 32:217-30, vii. [PMID: 15862619 DOI: 10.1016/j.ucl.2005.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Urothelial transitional cell cancer has a high rate of response to combination cytotoxic therapy. Approximately 50% of patients with high-grade bladder cancer and deep muscle invasion ultimately die of disseminated disease. Translating the high response seen in locally advanced disease into long-term survival in the metastatic setting and to improved survival in the advanced setting has proved difficult. This article reviews the use of adjuvant chemotherapy in localized or locally advanced transitional cell cancer. The chemotherapy of urological malignancies, including bladder cancer, has recently been reviewed in detail; this article does not contain an extensive review of the drugs used.
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Affiliation(s)
- Ana M Aparicio
- Division of Medical Oncology and Kenneth J. Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Avenue, Los Angeles, CA 90089, USA
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268
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Drexler GA, Rogge S, Beisker W, Eckardt-Schupp F, Zdzienicka MZ, Fritz E. Spontaneous homologous recombination is decreased in Rad51C-deficient hamster cells. DNA Repair (Amst) 2005; 3:1335-43. [PMID: 15336628 DOI: 10.1016/j.dnarep.2004.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Revised: 05/04/2004] [Accepted: 05/05/2004] [Indexed: 11/29/2022]
Abstract
The Chinese hamster cell mutant, CL-V4B that is mutated in the Rad51 paralog gene, Rad51C (RAD51L2), has been described to exhibit increased sensitivity to DNA cross-linking agents, genomic instability, and an impaired Rad51 foci formation in response to DNA damage. To directly examine an effect of the Rad51C protein on homologous recombination (HR) in mammalian cells, we compared the frequencies and rates of spontaneous HR in CL-V4B cells and in parental wildtype V79B cells, using a recombination reporter plasmid in host cell reactivation assays. Our results demonstrate that HR is reduced but not abolished in the CL-V4B mutant. We thus, provide direct evidence for a role of mammalian Rad51C in HR processes. The reduced HR events described here help to explain the deficient phenotypes observed in Rad51C mutants and support an accessory role of Rad51C in Rad51-mediated recombination.
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Affiliation(s)
- Guido A Drexler
- Institute of Molecular Radiobiology, GSF-National Research Center for Environment and Health, Neuherberg D-85758, Germany
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269
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Barber LJ, Ward TA, Hartley JA, McHugh PJ. DNA interstrand cross-link repair in the Saccharomyces cerevisiae cell cycle: overlapping roles for PSO2 (SNM1) with MutS factors and EXO1 during S phase. Mol Cell Biol 2005; 25:2297-309. [PMID: 15743825 PMCID: PMC1061624 DOI: 10.1128/mcb.25.6.2297-2309.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pso2/Snm1 is a member of the beta-CASP metallo-beta-lactamase family of proteins that include the V(D)J recombination factor Artemis. Saccharomyces cerevisiae pso2 mutants are specifically sensitive to agents that induce DNA interstrand cross-links (ICLs). Here we establish a novel overlapping function for PSO2 with MutS mismatch repair factors and the 5'-3' exonuclease Exo1 in the repair of DNA ICLs, which is confined to S phase. Our data demonstrate a requirement for NER and Pso2, or Exo1 and MutS factors, in the processing of ICLs, and this is required prior to the repair of ICL-induced DNA double-strand breaks (DSBs) that form during replication. Using a chromosomally integrated inverted-repeat substrate, we also show that loss of both pso2 and exo1/msh2 reduces spontaneous homologous recombination rates. Therefore, PSO2, EXO1, and MSH2 also appear to have overlapping roles in the processing of some forms of endogenous DNA damage that occur at an irreversibly collapsed replication fork. Significantly, our analysis of ICL repair in cells synchronized for each cell cycle phase has revealed that homologous recombination does not play a major role in the direct repair of ICLs, even in G2, when a suitable template is readily available. Rather, we propose that recombination is primarily involved in the repair of DSBs that arise from the collapse of replication forks at ICLs. These findings have led to considerable clarification of the complex genetic relationship between various ICL repair pathways.
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Affiliation(s)
- Louise J Barber
- Cancer Research UK Drug-DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, University College London, London
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270
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Kimura S, Saotome A, Uchiyama Y, Mori Y, Tahira Y, Sakaguchi K. The expression of the rice (Oryza sativa L.) homologue of Snm1 is induced by DNA damages. Biochem Biophys Res Commun 2005; 329:668-72. [PMID: 15737637 DOI: 10.1016/j.bbrc.2005.01.161] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Indexed: 10/25/2022]
Abstract
We isolated and characterized the rice homologue of the DNA repair gene Snm1 (OsSnm1). The length of the cDNA was 1862bp; the open reading frame encoded a predicted product of 485 amino acid residues with a molecular mass of 53.2kDa. The OsSnm1 protein contained the conserved beta-lactamase domain in its internal region. OsSnm1 was expressed in all rice organs. The expression was induced by MMS, H(2)O(2), and mitomycin C, but not by UV. Transient expression of an OsSnm1/GFP fusion protein in onion epidermal cells revealed the localization of OsSnm1 to the nucleus. These results suggest that OsSnm1 is involved not only in the repair of DNA interstrand crosslinks, but also in various other DNA repair pathways.
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Affiliation(s)
- Seisuke Kimura
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan
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271
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Abdel-Halim HI, Natarajan AT, Mullenders LHF, Boei JJWA. Mitomycin C-induced pairing of heterochromatin reflects initiation of DNA repair and chromatid exchange formation. J Cell Sci 2005; 118:1757-67. [PMID: 15797924 DOI: 10.1242/jcs.02306] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chromatid interchanges induced by the DNA cross-linking agent mitomycin C (MMC) are over-represented in human chromosomes containing large heterochromatic regions. We found that nearly all exchange breakpoints of chromosome 9 are located within the paracentromeric heterochromatin and over 70% of exchanges involving chromosome 9 are between its homologues. We provide evidence that the required pairing of chromosome 9 heterochromatic regions occurs in G(0)/G(1) and S-phase cells as a result of an active cellular process initiated upon MMC treatment. By contrast, no pairing was observed for a euchromatic paracentromeric region of the equal-sized chromosome 8. The MMC-induced pairing of chromosome 9 heterochromatin is observed in a subset of cells; its percentage closely mimics the frequency of homologous interchanges found at metaphase. Moreover, the absence of pairing in cells derived from XPF patients correlates with an altered spectrum of MMC-induced exchanges. Together, the data suggest that the heterochromatin-specific pairing following MMC treatment reflects the initiation of DNA cross-link repair and the formation of exchanges.
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MESH Headings
- Cells, Cultured
- Chromosome Pairing/drug effects
- Chromosome Pairing/physiology
- Chromosomes, Human, Pair 8/drug effects
- Chromosomes, Human, Pair 8/physiology
- Chromosomes, Human, Pair 9/drug effects
- Chromosomes, Human, Pair 9/physiology
- Cross-Linking Reagents/pharmacology
- DNA Damage/drug effects
- DNA Damage/physiology
- DNA Repair/drug effects
- DNA Repair/physiology
- G1 Phase/drug effects
- G1 Phase/physiology
- Heterochromatin/drug effects
- Heterochromatin/physiology
- Humans
- Interphase/physiology
- Metaphase/physiology
- Mitomycin/pharmacology
- Resting Phase, Cell Cycle/drug effects
- Resting Phase, Cell Cycle/physiology
- S Phase/drug effects
- S Phase/physiology
- Sequence Homology, Nucleic Acid
- Sister Chromatid Exchange/drug effects
- Sister Chromatid Exchange/physiology
- Xeroderma Pigmentosum/genetics
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Affiliation(s)
- H I Abdel-Halim
- Department of Toxicogenetics, Leiden University Medical Center, PO Box 9503, 2300 RA Leiden, The Netherlands
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272
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Yun J, Zhong Q, Kwak JY, Lee WH. Hypersensitivity of Brca1-deficient MEF to the DNA interstrand crosslinking agent mitomycin C is associated with defect in homologous recombination repair and aberrant S-phase arrest. Oncogene 2005; 24:4009-16. [PMID: 15782115 DOI: 10.1038/sj.onc.1208575] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hypersensitivity of Brca1-deficient cells to interstrand crosslinking (ICL) agents such as cisplatin and mitomycin C (MMC) implicates an important role for Brca1 in cellular response to the ICL DNA damage repair. However, the detailed mechanism of how Brca1 is involved in the ICL response remains unclear. In this study, we analysed the cellular response to MMC treatment using isogenic mouse embryonic fibroblasts (MEFs) including wild type, p53-/- and p53-/-Brca1-/-. Marked hypersensitivity of p53-/- Brca1-/- MEFs to MMC was found, and the reconstitution of Brca1 expression in these cells restored resistance to MMC. Upon MMC treatment, wild-type MEF was temporarily arrested at G2/M phase but subsequently resumed a normal cell cycle progression. In contrast, Brca1-deficient MEF exhibited a marked time-dependent accumulation of cells arrested at S phase and a prolonged increase in the G2/M population, followed by extensive cell deaths. Importantly, DNA damage-induced Rad51 foci were not formed in these cells, suggesting a defect in homologous recombination. Such defects are fully rescued by reconstitution of Brca1 expression in Brca1-deficient MEF, suggesting that Brca1 directly plays an essential role in ICL repair, which depends on homologous recombination during S phase.
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Affiliation(s)
- Jeanho Yun
- Medical Research Center for Cancer Molecular Therapy, College of Medicine, Dong-A University, Busan 602-714, South Korea
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273
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Nohmi T, Masumura KI. Molecular nature of intrachromosomal deletions and base substitutions induced by environmental mutagens. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2005; 45:150-161. [PMID: 15668939 DOI: 10.1002/em.20110] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cellular DNA is exposed to a variety of exogenous and endogenous mutagens. A complete understanding of the importance of different types of DNA damage requires knowledge of the specific molecular alterations induced by different types of agents in specific target tissues in vivo. The gpt delta transgenic mouse model provides the opportunity to characterize tissue-specific DNA alterations because small and large deletions as well as base substitutions can be analyzed. Here, we summarize the characteristics of intrachromosomal deletions and base substitutions induced by ionizing radiation in liver and spleen, ultraviolet B (UVB) radiation in epidermis, mitomycin C (MMC) in bone marrow, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in colon, and aminophenylnorharman (APNH) in liver of gpt delta mice. Carbon-ion radiation, UVB, and MMC induced large deletions of more than 1 kb. About half of the large deletions occurred between short direct-repeat sequences and the remainder had flush ends, suggesting the involvement of nonhomologous end joining of double-stranded breaks (DSBs) in DNA. UV photoproducts and interstrand crosslinks by MMC may block DNA replication, thereby inducing DSBs. In contrast, PhIP and APNH mainly generated 1 bp deletions in runs of guanine bases. As for base substitutions, UVB and MMC induced G:C-->A:T transitions at dipyrimidine sites and tandem base substitutions at GG sites, respectively. PhIP and APNH induced G:C-->T:A transversions. Translesion DNA synthesis across the lesions, i.e., UV photoproducts, intrastrand crosslinks by MMC, and guanine adducts by the heterocyclic amines, may be involved in the induction of base substitutions. These results indicate the importance of sequence information to elucidate the mechanisms underlying deletions and base substitutions induced in vivo by environmental mutagens.
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Affiliation(s)
- Takehiko Nohmi
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Tokyo, Japan.
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274
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Laurencon A, Orme CM, Peters HK, Boulton CL, Vladar EK, Langley SA, Bakis EP, Harris DT, Harris NJ, Wayson SM, Hawley RS, Burtis KC. A large-scale screen for mutagen-sensitive loci in Drosophila. Genetics 2005; 167:217-31. [PMID: 15166149 PMCID: PMC1470880 DOI: 10.1534/genetics.167.1.217] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In a screen for new DNA repair mutants, we tested 6275 Drosophila strains bearing homozygous mutagenized autosomes (obtained from C. Zuker) for hypersensitivity to methyl methanesulfonate (MMS) and nitrogen mustard (HN2). Testing of 2585 second-chromosome lines resulted in the recovery of 18 mutants, 8 of which were alleles of known genes. The remaining 10 second-chromosome mutants were solely sensitive to MMS and define 8 new mutagen-sensitive genes (mus212-mus219). Testing of 3690 third chromosomes led to the identification of 60 third-chromosome mutants, 44 of which were alleles of known genes. The remaining 16 mutants define 14 new mutagen-sensitive genes (mus314-mus327). We have initiated efforts to identify these genes at the molecular level and report here the first two identified. The HN2-sensitive mus322 mutant defines the Drosophila ortholog of the yeast snm1 gene, and the MMS- and HN2-sensitive mus301 mutant defines the Drosophila ortholog of the human HEL308 gene. We have also identified a second-chromosome mutant, mus215(ZIII-2059), that uniformly reduces the frequency of meiotic recombination to <3% of that observed in wild type and thus defines a function required for both DNA repair and meiotic recombination. At least one allele of each new gene identified in this study is available at the Bloomington Stock Center.
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Affiliation(s)
- Anne Laurencon
- Section of Molecular and Cellular Biology, University of California, Davis, California 95616, USA
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275
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Genomic Instability:Signaling Pathways Orchestrating the Responsesto Ionizing Radiation and Cisplatin. Genome Integr 2005. [DOI: 10.1007/7050_010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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276
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Atanassov B, Gospodinov A, Stoimenov I, Mladenov E, Russev G, Tsaneva I, Anachkova B. Repair of DNA interstrand crosslinks may take place at the nuclear matrix. J Cell Biochem 2005; 96:126-36. [PMID: 16052506 DOI: 10.1002/jcb.20518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Host cell reactivation assay using Trioxsalen-crosslinked plasmid pEGFP-N1 showed that human cells were able to repair Trioxsalen interstrand crosslinks (ICL). To study the mechanism of this repair pathway, cells were transfected with the plasmids pEGFP-1, which did not contain the promoter of the egfp gene, and with pEGFP-G-, which did not contain the egfp gene. Neither of these plasmids alone was able to express the green fluorescent protein. After cotransfection with the two plasmids, 1%-2% of the cells developed fluorescent signal, which showed that recombination events had taken place in these cells to create DNA constructs containing the promoter and the gene properly aligned. When one or both of the plasmids were crosslinked with Trioxsalen, the recombination rate increased several fold. To identify the nuclear compartment where recombination takes place, cells were transfected with crosslinked pEGFP-N1 and the amount of plasmid DNA in the different nuclear fractions was determined. The results showed that Trioxsalen crosslinking increased the percentage of matrix attached plasmid DNA in a dose-dependent way. Immunoblotting experiments showed that after transfection with Trioxsalen crosslinked plasmids the homologous recombination protein Rad51 also associated with the nuclear matrix fraction. These studies provide a model system for investigating the precise molecular mechanisms that appear to couple repair of DNA ICL with nuclear matrix attachment.
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Affiliation(s)
- Boyko Atanassov
- Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
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277
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Ishiai M, Kimura M, Namikoshi K, Yamazoe M, Yamamoto K, Arakawa H, Agematsu K, Matsushita N, Takeda S, Buerstedde JM, Takata M. DNA cross-link repair protein SNM1A interacts with PIAS1 in nuclear focus formation. Mol Cell Biol 2004; 24:10733-41. [PMID: 15572677 PMCID: PMC533992 DOI: 10.1128/mcb.24.24.10733-10741.2004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 08/27/2004] [Accepted: 09/21/2004] [Indexed: 11/20/2022] Open
Abstract
The yeast SNM1/PSO2 gene specifically functions in DNA interstrand cross-link (ICL) repair, and its role has been suggested to be separate from other DNA repair pathways. In vertebrates, there are three homologs of SNM1 (SNM1A, SNM1B, and SNM1C/Artemis; SNM1 family proteins) whose functions are largely unknown. We disrupted each of the SNM1 family genes in the chicken B-cell line DT40. Both SNM1A- and SNM1B-deficient cells were sensitive to cisplatin but not to X-rays, whereas SNM1C/Artemis-deficient cells exhibited sensitivity to X-rays but not to cisplatin. SNM1A was nonepistatic with XRCC3 (homologous recombination), RAD18 (translesion synthesis), FANCC (Fanconi anemia), and SNM1B in ICL repair. SNM1A protein formed punctate nuclear foci depending on the conserved SNM1 (metallo-beta-lactamase) domain. PIAS1 was found to physically interact with SNM1A, and they colocalized at nuclear foci. Point mutations in the SNM1 domain, which disrupted the interaction with PIAS1, led to mislocalization of SNM1A in the nucleus and loss of complementation of snm1a cells. These results suggest that interaction between SNM1A and PIAS1 is required for ICL repair.
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Affiliation(s)
- Masamichi Ishiai
- Department of Immunology and Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan
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278
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Abstract
A subset of human cancer syndromes result from inherited defects in genes responsible for DNA repair. During the past few years, discoveries concerning the intersection of certain DNA repair processes have increased our understanding of how the disruption of specific DNA repair mechanisms leads to genomic instability and tumorigenesis. This review focuses on the human genes MUTYH, BRCA2/FANCD1, and BLM.
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Affiliation(s)
- Mary A Risinger
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
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279
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Johansson F, Lagerqvist A, Erixon K, Jenssen D. A method to monitor replication fork progression in mammalian cells: nucleotide excision repair enhances and homologous recombination delays elongation along damaged DNA. Nucleic Acids Res 2004; 32:e157. [PMID: 15537835 PMCID: PMC534636 DOI: 10.1093/nar/gnh154] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Revised: 10/22/2004] [Accepted: 10/22/2004] [Indexed: 12/28/2022] Open
Abstract
The capacity to rescue stalled replication forks (RFs) is important for the maintenance of cell viability and genome integrity. Here, we have developed a novel method for monitoring RF progression and the influence of DNA lesions on this process. The method is based on the principle that each RF is expected to be associated with a pair of single-stranded ends, which can be analyzed by employing strand separation in alkali. This method was applied to examine the rate of RF progression in Chinese hamster cell lines deficient in ERCC1, which is involved in nucleotide excision repair (NER), or in XRCC3, which participates in homologous recombination repair, following irradiation with ultraviolet (UV) light or exposure to benzo(a)pyrene-7,8-diol-9,10-epoxide (BPDE). The endpoints observed were cell survival, NER activity, formation of double-strand breaks and the rate of RF progression. Subsequently, we attempted to explain our observation that cells deficient in XRCC3 (irs1SF) exhibit enhanced sensitivity to UV radiation and BPDE. irs1SF cells demonstrated a capacity for NER that was comparable with wild-type AA8 cells, but the rate of RF progression was even higher than that for the wild-type AA8 cells. As expected, cells deficient in ERCC1 (UV4) showed no NER activity and were hypersensitive to both UV radiation and BPDE. The observation that cells deficient in NER displayed a pronounced delay in RF progression indicates that NER plays an important role in maintaining fork progression along damaged DNA. The elevated rate of RF progression in XRCC3-deficient cells indicates that this protein is involved in a time-consuming process which resolves stalled RFs.
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Affiliation(s)
- Fredrik Johansson
- Department of Genetics, Microbiology and Toxicology, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
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280
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Hartley JA, Spanswick VJ, Brooks N, Clingen PH, McHugh PJ, Hochhauser D, Pedley RB, Kelland LR, Alley MC, Schultz R, Hollingshead MG, Schweikart KM, Tomaszewski JE, Sausville EA, Gregson SJ, Howard PW, Thurston DE. SJG-136 (NSC 694501), a novel rationally designed DNA minor groove interstrand cross-linking agent with potent and broad spectrum antitumor activity: part 1: cellular pharmacology, in vitro and initial in vivo antitumor activity. Cancer Res 2004; 64:6693-9. [PMID: 15374986 DOI: 10.1158/0008-5472.can-03-2941] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
SJG-136 (NSC 694501) is a rationally designed pyrrolobenzodiazepine dimer that binds in the minor groove of DNA. It spans 6 bp with a preference for binding to purine-GATC-pyrimidine sequences. The agent has potent activity in the National Cancer Institute (NCI) anticancer drug screen with 50% net growth inhibition conferred by 0.14 to 320 nmol/L (7.4 nmol/L mean). Sensitive cell lines exhibit total growth inhibition and 50% lethality after treatment with as little as 0.83 and 7.1 nmol/L SJG-136, respectively. COMPARE and molecular target analysis of SJG-136 data versus that of >60,000 compounds tested in the NCI 60 cell line screen shows that, although the agent has similarity to other DNA binding agents, the pattern of activity for SJG-136 does not fit within the clusters of any known agents, suggesting that SJG-136 possesses a distinct mechanism of action. Testing in the NCI standard hollow fiber assay produced prominent growth inhibition in 20 of 24 i.p. and 7 of 24 s.c. test combinations with 5 of 12 cell lines exhibiting cell kill. In addition, SJG-136 produced antitumor activity in mice bearing CH1 and CH1cisR xenografts, a cisplatin-resistant human ovarian tumor model, and also in mice bearing LS174T xenografts, a human colon tumor model. SJG-136 produces DNA interstrand cross-links between two N-2 guanine positions on opposite strands and separated by 2 bp. In human tumor cell lines, the cross-links form rapidly and persist compared with those produced by conventional cross-linking agents such as nitrogen mustards. In mice bearing the LS174T human colon xenograft, DNA interstrand cross-links can be detected in tumor cells using a modification of the single cell gel electrophoresis (comet) assay after administration of a therapeutic dose. Cross-links in the tumor increase with dose and are clearly detectable at 1 hour after i.v. administration. The level of cross-linking persists over a 24-hour period in this tumor in contrast to cross-links produced by conventional cross-linking agents observed over the same time period.
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Affiliation(s)
- John A Hartley
- Cancer Research UK Drug-DNA Interactions Research Group, Department of Oncology, Royal Free and University College Medical School, London, United Kingdom.
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281
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Lan L, Hayashi T, Rabeya RM, Nakajima S, Kanno SI, Takao M, Matsunaga T, Yoshino M, Ichikawa M, Riele HT, Tsuchiya S, Tanaka K, Yasui A. Functional and physical interactions between ERCC1 and MSH2 complexes for resistance to cis-diamminedichloroplatinum(II) in mammalian cells. DNA Repair (Amst) 2004; 3:135-43. [PMID: 14706347 DOI: 10.1016/j.dnarep.2003.10.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bulky DNA lesions are mainly repaired by nucleotide excision repair (NER), in which the interaction of ERCC1 with XPA protein recruits the ERCC1-XPF complex, which acts as a structure-specific endonuclease in the repair process. However, additional functions besides NER have been suggested for the ERCC1-XPF complex, because ERCC1- or XPF-deficient rodent cells are significantly more sensitive to DNA interstrand cross-linking (ICL) agents such as cis-diamminedichloroplatinum(II) (CDDP) than any other NER-deficient cells and because ERCC1-deficient mice suffer a more severe phenotype than XPA-deficient mice. By using RNA interference we show here that suppression of ERCC1 expression increases the sensitivity of xeroderma pigmentosum group A (XPA)-deficient human cells to CDDP but not to UV. This increased sensitivity to CDDP is observed in mouse cells defective in Xpa as well but not in cells defective both in Xpa and the mismatch repair gene Msh2. These data suggest that ERCC1 and MSH2 are involved co-operatively in CDDP resistance in mammalian cells. As a possible molecular basis, we show further a physical interaction between endogenous ERCC1 and MSH2 complexes in HeLa cell extracts. Using tagged ERCC1 in COS7 cells, the minimum region in ERCC1 necessary for the immuno-precipitation of MSH2 is turned out to be the carboxyl-terminal domain between the 184th and 260th amino acid, which is partly overlapping with the XPF-binding domain of ERCC1. This interaction may be important in additional functions of ERCC1-XPF including the repair of CDDP-induced DNA damage.
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Affiliation(s)
- Li Lan
- Department of Molecular Genetics, Aging and Cancer, Tohoku University, 980-8575 Sendai, Japan
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282
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Friedmann B, Caplin M, Hartley JA, Hochhauser D. Modulation of DNA Repair In vitro after Treatment with Chemotherapeutic Agents by the Epidermal Growth Factor Receptor Inhibitor Gefitinib (ZD1839). Clin Cancer Res 2004; 10:6476-86. [PMID: 15475435 DOI: 10.1158/1078-0432.ccr-04-0586] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The epidermal growth factor receptor (EGFR) is commonly expressed in human tumors and provides a target for therapy. Gefitinib (Iressa, ZD1839) is a quinazoline derivative that inhibits EGFR tyrosine kinase activity. Gefitinib demonstrated anticancer efficacy in vivo, and although experiments in vitro have suggested that inhibition of EGFR modulates the activity of chemotherapeutic agents, the mechanism of this interaction is unclear. We investigated mechanisms for this modulation. EXPERIMENTAL DESIGN The antiproliferative effect of gefitinib alone or combined with cisplatin, melphalan, and etoposide was determined in a human breast (MCF-7) cancer cell line. Using the alkaline single-cell gel electrophoresis (comet) assay, we investigated kinetics of DNA damage and repair after treatment with the chemotherapeutic drugs combined with gefitinib. To investigate whether the phosphatidylinositol 3'-kinase pathway was contributing to repair-inhibition produced by gefitinib, cells were exposed to chemotherapy in combination with the phosphatidylinositol 3'-kinase inhibitor LY294002. RESULTS A superadditive (synergistic) increase in growth inhibition for combined treatment with gefitinib was found for cisplatin and etoposide, but not with melphalan. There was delayed repair of DNA strand breaks after treatment with etoposide combined with gefitinib, and repair of DNA interstrand cross-links produced by cisplatin is delayed in combination with gefitinib. Inhibition of cell proliferation and DNA repair was identical in cells treated with LY294002. Immunoprecipitation of cell extracts demonstrated that after exposure to gefitinib, there was an association between EGFR and DNA-PK(CS). CONCLUSION Gefitinib acts through inhibition of repair of cisplatin and etoposide-induced DNA damage; this effect is mimicked by inhibitors of the phosphatidylinositol 3'-kinase suggesting similar mechanisms of action.
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Affiliation(s)
- Benjamin Friedmann
- Department of Oncology, Royal Free and University College Medical School, University College London, London, United Kingdom
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283
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Demuth I, Digweed M, Concannon P. Human SNM1B is required for normal cellular response to both DNA interstrand crosslink-inducing agents and ionizing radiation. Oncogene 2004; 23:8611-8. [PMID: 15467758 DOI: 10.1038/sj.onc.1207895] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
DNA interstrand crosslinks (ICLs) are critical lesions for the mammalian cell since they affect both DNA strands and block transcription and replication. The repair of ICLs in the mammalian cell involves components of different repair pathways such as nucleotide-excision repair and the double-strand break/homologous recombination repair pathways. However, the mechanistic details of mammalian ICL repair have not been fully delineated. We describe here the complete coding sequence and the genomic organization of hSNM1B, one of at least three human homologs of the Saccharomyces cerevisiae PSO2 gene. Depletion of hSNM1B by RNA interference rendered cells hypersensitive to ICL-inducing agents. This requirement for hSNM1B in the cellular response to ICL has been hypothesized before but never experimentally verified. In addition, siRNA knockdown of hSNM1B rendered cells sensitive to ionizing radiation, suggesting the possibility of hSNM1B involvement in homologous recombination repair of double-strand breaks arising as intermediates of ICL repair. Monoubiquitination of FANCD2, a key step in the FANC/BRCA pathway, is not affected in hSNM1B-depleted HeLa cells, indicating that hSNM1B is probably not a part of the Fanconi anemia core complex. Nonetheless, similarities in the phenotype of hSNM1B-depleted cells and cultured cells from patients suffering from Fanconi anemia make hSNM1B a candidate for one of the as yet unidentified Fanconi anemia genes not involved in monoubiquitination of FANCD2.
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Affiliation(s)
- Ilja Demuth
- Molecular Genetics Program, Benaroya Research Institute, Seattle, WA 98101-2795, USA
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284
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Molinier J, Stamm ME, Hohn B. SNM-dependent recombinational repair of oxidatively induced DNA damage in Arabidopsis thaliana. EMBO Rep 2004; 5:994-9. [PMID: 15448639 PMCID: PMC1299156 DOI: 10.1038/sj.embor.7400256] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2004] [Revised: 07/28/2004] [Accepted: 08/23/2004] [Indexed: 01/14/2023] Open
Abstract
Two different roles for SNM (sensitive to nitrogen mustard) proteins have already been described: the SNM1/PSO2-related proteins are involved in the repair of the interstrand crosslink (ICL) and the ARTEMIS proteins are involved in the V(D)J recombination process. Our study shows that an Arabidopsis SNM protein, although structurally closer to the SNM1/PSO2 members, shares some properties with ARTEMIS but also has novel characteristics. Arabidopsis plants defective for the expression of AtSNM1 did not show hypersensitivity to the ICL-forming agents but to the chemotherapeutic agent bleomycin and to H(2)O(2). AtSNM1 mutant plants are delayed in the repair of oxidative damage and did not show enhancement of the frequency of somatic homologous recombination on exposure to H(2)O(2) and to the bacterial elicitor flagellin, both inducing oxidative stress, as observed in the control plants. Therefore, our results suggest the existence, in plants, of a novel SNM-dependent recombinational repair process of oxidatively induced DNA damage.
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Affiliation(s)
- Jean Molinier
- Friedrich Miescher-Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland.
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285
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Koeppel F, Poindessous V, Lazar V, Raymond E, Sarasin A, Larsen AK. Irofulven cytotoxicity depends on transcription-coupled nucleotide excision repair and is correlated with XPG expression in solid tumor cells. Clin Cancer Res 2004; 10:5604-13. [PMID: 15328203 DOI: 10.1158/1078-0432.ccr-04-0442] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Irofulven is a novel alkylating agent with promising clinical activity, particularly toward ovarian and hormone-refractory prostate cancers. To facilitate additional clinical development, we have aimed to identify biological markers associated with sensitivity to the compound. METHODS Fibroblasts derived from patients with xeroderma pigmentosum or Cockayne's syndrome along with a panel of 20 human cancer cell lines (eight different tumor types) were examined to establish the importance of nucleotide excision repair proteins in the sensitivity to irofulven. RESULTS Human cells deficient in nucleotide excision repair are up to 30-fold more sensitive to the cytotoxic effects of irofulven compared with repair-proficient controls, clearly indicating that nucleotide excision repair plays a crucial role in the sensitivity to the drug. Interestingly, our results show that irofulven-induced lesions are recognized by transcription-coupled repair but not by global genome repair. Another unique feature is the pronounced sensitivity of XPD and XPB helicase-deficient cells to the drug. Comparison of the IC50 values for irofulven, cisplatin, and ecteinascidin 743 with the expression levels of ERCC1, XPD, and XPG genes in different solid tumor cell lines shows no correlation between the expression levels of any of the three nucleotide excision repair proteins and the sensitivity to ecteinascidin 743. In contrast, expression of the XPG endonuclease was correlated with the cytotoxicity for irofulven and, to a lesser degree, for cisplatin. Importantly, XPG expression was also correlated with cellular nucleotide excision repair activity. CONCLUSIONS Increasing evidence indicates that compromised nucleotide excision repair activity is frequent in several solid tumor types. The results presented here suggest that XPG expression in such tumors may be a useful marker to predict their sensitivity to irofulven.
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Affiliation(s)
- Florence Koeppel
- Group of Biology and Pharmacogenetics of Human Tumors, Centre National de la Recherche Scientifique, UMR 8113, Institut Gustave-Roussy, Villejuif, France
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286
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Pichierri P, Franchitto A, Rosselli F. BLM and the FANC proteins collaborate in a common pathway in response to stalled replication forks. EMBO J 2004; 23:3154-63. [PMID: 15257300 PMCID: PMC514912 DOI: 10.1038/sj.emboj.7600277] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Accepted: 05/25/2004] [Indexed: 12/28/2022] Open
Abstract
Fanconi anaemia (FA) and Bloom syndrome (BS) are autosomal recessive diseases characterised by chromosome fragility and cancer proneness. Here, we report that BLM and the FA pathway are activated in response to both crosslinked DNA and replication fork stall. We provide evidence that BLM and FANCD2 colocalise and co-immunoprecipitate following treatment with either DNA crosslinkers or agents inducing replication arrest. We also find that the FA core complex is necessary for BLM phosphorylation and assembly in nuclear foci in response to crosslinked DNA. Moreover, we show that knock-down of the MRE11 complex, whose function is also under the control of the FA core complex, enhances cellular and chromosomal sensitivity to DNA interstrand crosslinks in BS cells. These findings suggest the existence of a functional link between BLM and the FA pathway and that BLM and the MRE11 complex are in two separated branches of a pathway resulting in S-phase checkpoint activation, chromosome integrity and cell survival in response to crosslinked DNA.
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Affiliation(s)
- Pietro Pichierri
- UPR2169 CNRS, ‘Genetic Instability and Cancer', Institut Gustave Roussy, Pavillon de Recherche, Rue Camille Desmoulins, Villejuif, France
| | - Annapaola Franchitto
- UPR2169 CNRS, ‘Genetic Instability and Cancer', Institut Gustave Roussy, Pavillon de Recherche, Rue Camille Desmoulins, Villejuif, France
| | - Filippo Rosselli
- UPR2169 CNRS, ‘Genetic Instability and Cancer', Institut Gustave Roussy, Pavillon de Recherche, Rue Camille Desmoulins, Villejuif, France
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287
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Niedernhofer LJ, Odijk H, Budzowska M, van Drunen E, Maas A, Theil AF, de Wit J, Jaspers NGJ, Beverloo HB, Hoeijmakers JHJ, Kanaar R. The structure-specific endonuclease Ercc1-Xpf is required to resolve DNA interstrand cross-link-induced double-strand breaks. Mol Cell Biol 2004; 24:5776-87. [PMID: 15199134 PMCID: PMC480908 DOI: 10.1128/mcb.24.13.5776-5787.2004] [Citation(s) in RCA: 391] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2003] [Revised: 01/07/2004] [Accepted: 04/06/2004] [Indexed: 11/20/2022] Open
Abstract
Interstrand cross-links (ICLs) are an extremely toxic class of DNA damage incurred during normal metabolism or cancer chemotherapy. ICLs covalently tether both strands of duplex DNA, preventing the strand unwinding that is essential for polymerase access. The mechanism of ICL repair in mammalian cells is poorly understood. However, genetic data implicate the Ercc1-Xpf endonuclease and proteins required for homologous recombination-mediated double-strand break (DSB) repair. To examine the role of Ercc1-Xpf in ICL repair, we monitored the phosphorylation of histone variant H2AX (gamma-H2AX). The phosphoprotein accumulates at DSBs, forming foci that can be detected by immunostaining. Treatment of wild-type cells with mitomycin C (MMC) induced gamma-H2AX foci and increased the amount of DSBs detected by pulsed-field gel electrophoresis. Surprisingly, gamma-H2AX foci were also induced in Ercc1(-/-) cells by MMC treatment. Thus, DSBs occur after cross-link damage via an Ercc1-independent mechanism. Instead, ICL-induced DSB formation required cell cycle progression into S phase, suggesting that DSBs are an intermediate of ICL repair that form during DNA replication. In Ercc1(-/-) cells, MMC-induced gamma-H2AX foci persisted at least 48 h longer than in wild-type cells, demonstrating that Ercc1 is required for the resolution of cross-link-induced DSBs. MMC triggered sister chromatid exchanges in wild-type cells but chromatid fusions in Ercc1(-/-) and Xpf mutant cells, indicating that in their absence, repair of DSBs is prevented. Collectively, these data support a role for Ercc1-Xpf in processing ICL-induced DSBs so that these cytotoxic intermediates can be repaired by homologous recombination.
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Affiliation(s)
- Laura J Niedernhofer
- Department of Cell Biology and Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
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288
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Saffran WA, Ahmed S, Bellevue S, Pereira G, Patrick T, Sanchez W, Thomas S, Alberti M, Hearst JE. DNA repair defects channel interstrand DNA cross-links into alternate recombinational and error-prone repair pathways. J Biol Chem 2004; 279:36462-9. [PMID: 15213235 DOI: 10.1074/jbc.m402323200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The repair of psoralen interstrand cross-links in the yeast Saccharomyces cerevisiae involves the DNA repair groups nucleotide excision repair (NER), homologous recombination (HR), and post-replication repair (PRR). In repair-proficient yeast cells cross-links induce double-strand breaks, in an NER-dependent process; the double-strand breaks are then repaired by HR. An alternate error-prone repair pathway generates mutations at cross-link sites. We have characterized the repair of plasmid molecules carrying a single psoralen cross-link, psoralen monoadduct, or double-strand break in yeast cells with deficiencies in NER, HR, or PRR genes, measuring the repair efficiencies and the levels of gene conversions, crossing over, and mutations. Strains with deficiencies in the NER genes RAD1, RAD3, RAD4, and RAD10 had low levels of cross-link-induced recombination but higher mutation frequencies than repair-proficient cells. Deletion of the HR genes RAD51, RAD52, RAD54, RAD55, and RAD57 also decreased induced recombination and increased mutation frequencies above those of NER-deficient yeast. Strains lacking the PRR genes RAD5, RAD6, and RAD18 did not have any cross-link-induced mutations but showed increased levels of recombination; rad5 and rad6 cells also had altered patterns of cross-link-induced gene conversion in comparison with repair-proficient yeast. Our observations suggest that psoralen cross-links can be repaired by three pathways: an error-free recombinational pathway requiring NER and HR and two PRR-dependent error-prone pathways, one NER-dependent and one NER-independent.
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Affiliation(s)
- Wilma A Saffran
- Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367, USA.
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289
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Sasaki MS, Takata M, Sonoda E, Tachibana A, Takeda S. Recombination repair pathway in the maintenance of chromosomal integrity against DNA interstrand crosslinks. Cytogenet Genome Res 2004; 104:28-34. [PMID: 15162012 DOI: 10.1159/000077463] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2003] [Accepted: 12/08/2003] [Indexed: 11/19/2022] Open
Abstract
DNA interstrand crosslinks (ICL) present a major threat to cell viability and genome integrity. In eukaryotic cells, the ICLs have been suggested to be repaired by a complex process involving Xpf/Ercc1-mediated endonucleolytic incision and homologous recombination (HR). However, the entire feature of the ICL tolerating mechanism is still poorly understood. Here we studied chromosome aberrations (CA) and sister chromatid exchanges (SCE) by the use of the crosslinking agent mitomycin C (MMC), in chicken DT40 cells with the HR genes disrupted by targeted replacement. The disruption of the Rad54, Rad51B, Rad51C, Rad51D, Xrcc2 and Xrcc3 genes resulted in a dramatic reduction of spontaneous and MMC-induced SCEs. Interestingly, while HR-deficient cells were hypersensitive to cell killing by MMC, MMC-induced CAs were also suppressed in the HR-deficient cells except for Rad51D-, Xrcc2- and Xrcc3-deficient cells. These observations indicate that DNA double strand breaks (DSB) at stalled replication forks and those arising as repair intermediates present strong signals to cell death but can be tolerated by the HR repair pathway, where Rad54, Rad51B and Rad51C have an initiative role and repair can be completed by their paralogs Rad51D, Xrcc2 and Xrcc3. The impairment of the HR pathway, which otherwise leads to cell death, may be somewhat substituted by an alternative mechanism such as the Mre11/Rad50/Nbs1 pathway, resulting in reduced frequencies of SCEs and CAs.
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Affiliation(s)
- M S Sasaki
- Radiation Biology Center, Kyoto University, Kyoto, Japan.
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290
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Molinier J, Ramos C, Fritsch O, Hohn B. CENTRIN2 modulates homologous recombination and nucleotide excision repair in Arabidopsis. THE PLANT CELL 2004; 16:1633-43. [PMID: 15155891 PMCID: PMC490051 DOI: 10.1105/tpc.021378] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Accepted: 03/17/2004] [Indexed: 05/17/2023]
Abstract
A genetic screen of a population of Arabidopsis thaliana lines exhibiting enhanced somatic homologous recombination yielded a mutant affected in expression of a gene encoding a caltractin-like protein (centrin). The hyperrecombinogenic phenotype could be reproduced using RNA interference (RNAi) technology. Both the original mutant and the RNAi plants exhibited a moderate UV-C sensitivity as well as a reduced efficiency of in vitro repair of UV-damaged DNA. Transcription profiling of the mutant showed that expression of components of the nucleotide excision repair (NER) pathway and of factors involved in other DNA repair processes were significantly changed. Our data suggest an indirect involvement of centrin in recombinational DNA repair via the modulation of the NER pathway. These findings thus point to a novel interconnection between an early step of NER and homologous recombination, which may play a critical role in plant DNA repair.
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Affiliation(s)
- Jean Molinier
- Friedrich Miescher-Institute for Biomedical Research, CH-4058 Basel, Switzerland.
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291
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Reynolds M, Peterson E, Quievryn G, Zhitkovich A. Human nucleotide excision repair efficiently removes chromium-DNA phosphate adducts and protects cells against chromate toxicity. J Biol Chem 2004; 279:30419-24. [PMID: 15087443 DOI: 10.1074/jbc.m402486200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracellular reduction of carcinogenic Cr(VI) leads to the extensive formation of Cr(III)-DNA phosphate adducts. Repair mechanisms for chromium and other DNA phosphate-based adducts are currently unknown in human cells. We found that nucleotide excision repair (NER)-proficient human cells rapidly removed chromium-DNA adducts, with an average t((1/2)) of 7.1 h, whereas NER-deficient XP-A, XP-C, and XP-F cells were severely compromised in their ability to repair chromium-DNA lesions. Activation of NER in Cr(VI)-treated human fibroblasts or lung epithelial H460 cells was manifested by XPC-dependent binding of the XPA protein to the nuclear matrix, which was also observed in UV light-treated (but not oxidant-stressed) cells. Intracellular replication of chromium-modified plasmids demonstrated increased mutagenicity of binary Cr(III)-DNA and ternary cysteine-Cr(III)-DNA adducts in cells with inactive NER. NER deficiency created by the loss of XPA in fibroblasts or by knockdown of this protein by stable expression of small interfering RNA in H460 cells increased apoptosis and clonogenic death by Cr(VI), providing genetic evidence for the role of monofunctional chromium-DNA adducts in the toxic effects of this metal. The rate of NER of chromium-DNA adducts under saturating conditions was calculated to be approximately 50,000 lesions/min/cell. Because chromium-DNA adducts cause only small changes in the DNA helix, rapid repair of these modifications in human cells indicates that the presence of major structural distortions in DNA is not required for the efficient detection of the damaged sites by NER proteins in vivo.
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Affiliation(s)
- Mindy Reynolds
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912, USA
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292
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Pichierri P, Rosselli F. The DNA crosslink-induced S-phase checkpoint depends on ATR-CHK1 and ATR-NBS1-FANCD2 pathways. EMBO J 2004; 23:1178-87. [PMID: 14988723 PMCID: PMC380971 DOI: 10.1038/sj.emboj.7600113] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2003] [Accepted: 01/12/2004] [Indexed: 02/07/2023] Open
Abstract
The genetic syndrome Fanconi anemia (FA) is characterized by aplastic anemia, cancer predisposition and hypersensitivity to DNA interstrand crosslinks (ICLs). FA proteins (FANCs) are thought to work in pathway(s) essential for dealing with crosslinked DNA. FANCs interact with other proteins involved in both DNA repair and S-phase checkpoint such as BRCA1, ATM and the RAD50/MRE11/NBS1 (RMN) complex. We deciphered the previously undefined pathway(s) leading to the ICLs-induced S-phase checkpoint and the role of FANCs in this process. We found that ICLs activate a branched pathway downstream of the ATR kinase: one branch depending on CHK1 activity and the other on the FANCs-RMN complex. The transient slow-down of DNA synthesis was abolished in cells lacking ATR, whereas CHK1-siRNA-treated cells, NBS1 or FA cells showed partial S-phase arrest. CHK1 RNAi in NBS1 or FA cells abolished the S-phase checkpoint, suggesting that CHK1 and FANCs/NBS1 proteins work on parallel pathways. Furthermore, we found that ICLs trigger ATR-dependent FANCD2 phosphorylation and FANCD2/ATR colocalization. This study demonstrates a novel relationship between the FA pathway(s) and the ATR kinase.
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Affiliation(s)
- Pietro Pichierri
- UPR 2169 du CNRS, Institut Gustave Roussy PR2, Villejuif Cedex, France
| | - Filippo Rosselli
- UPR 2169 du CNRS, Institut Gustave Roussy PR2, Villejuif Cedex, France
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293
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Guillonneau F, Guieysse AL, Nocentini S, Giovannangeli C, Praseuth D. Psoralen interstrand cross-link repair is specifically altered by an adjacent triple-stranded structure. Nucleic Acids Res 2004; 32:1143-53. [PMID: 14966263 PMCID: PMC373402 DOI: 10.1093/nar/gkh267] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Revised: 01/16/2004] [Accepted: 01/16/2004] [Indexed: 11/14/2022] Open
Abstract
Targeting DNA-damaging agents to specific DNA sites by using sequence-specific DNA ligands has been successful in directing genomic modifications. The understanding of repair processing of such targeted damage and the influence of the adjacent complex is largely unknown. In this way, directed interstrand cross-links (ICLs) have already been generated by psoralen targeting. The mechanisms responsible for ICL removal are far from being understood in mammalian cells, with the proposed involvement of both mutagenic and recombinogenic pathways. Here, a unique ICL was introduced at a selected site by photoactivation of a psoralen moiety with the use of psoralen conjugates of triplex-forming oligonucleotides. The processing of psoralen ICL was evaluated in vitro and in cells for two types of cross-linked substrates, either containing a psoralen ICL alone or with an adjacent triple-stranded structure. We show that the presence of a neighbouring triplex structure interferes with different stages of psoralen ICL processing: (i) the ICL-induced DNA repair synthesis in HeLa cell extracts is inhibited by the triplex structure, as measured by the efficiency of 'true' and futile repair synthesis, stopping at the ICL site; (ii) in HeLa cells, the ICL removal via a nucleotide excision repair (NER) pathway is delayed in the presence of a neighbouring triplex; and (iii) the binding to ICL of recombinant xeroderma pigmentosum A protein, which is involved in pre-incision recruitment of NER factors is impaired by the presence of the third DNA strand. These data characterize triplex-induced modulation of ICL repair pathways at specific steps, which might have implications for the controlled induction of targeted genomic modifications and for the associated cellular responses.
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Affiliation(s)
- F Guillonneau
- Laboratoire de Biophysique, INSERM U565, CNRS UMR5153, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France
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294
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Shorrocks J, Tobi SE, Latham H, Peacock JH, Eeles R, Eccles D, McMillan TJ. Primary fibroblasts from BRCA1 heterozygotes display an abnormal G1/S cell cycle checkpoint following UVA irradiation but show normal levels of micronuclei following oxidative stress or mitomycin C treatment. Int J Radiat Oncol Biol Phys 2004; 58:470-8. [PMID: 14751517 DOI: 10.1016/j.ijrobp.2003.09.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE There is evidence to suggest that the breast cancer predisposing gene, BRCA1, is involved in cell cycle control and the response to damage but mouse brca1+/- heterozygotes have no distinctive phenotype. Here the response to the three forms of cellular stress was examined in primary human fibroblasts from individuals with a +/+ or +/- genotype for BRCA1. METHODS AND MATERIALS Fibroblasts from individuals carrying mutations in the BRCA1 gene were compared with those from those wild-type for BRCA1 in their response to long wavelength uv (UVA), hydrogen peroxide, and mitomycin C (MMC). Cell cycle progression and micronucleus formation (MN) were used as end points. RESULTS After UVA treatment there was no difference between +/- and +/+ cells in the initial fall in DNA synthetic activity (G(1) arrest) but the reentry into S-phase was restored at a faster rate in the BRCA1+/- cells after UVA exposure. Thus, for three normal (+/+) cell lines irradiated in monolayer, S-phase values averaged 15 +/- 3.7% 14 h post-UVA (1 x 10(5) J/m(2)), as compared with 35.7 +/- 1.9 (range) for two BRCA1(+/-) strains. Because a defective G(1)/S checkpoint in BRCA1 heterozygotes could lead to a greater proportion of S-phase cells with unrepaired DNA damage (strand breaks) and a resultant increase in chromosomal instability, the frequency of micronuclei induced by UVA was examined. Three normal (+/+) and three mutant (+/-) strains (two of which were used in the cell cycle experiments) produced mean micronuclei frequencies of 0.077 +/- 0.016 and 0.094 +/- 0.04/binucleate cell respectively (not statistically significant), 48 h after UVA exposure. No differences were found between BRCA1+/+ and +/- cells in MN formation after treatment with MMC or hydrogen peroxide. CONCLUSION Our data suggest a defective G(1)/S checkpoint in cells from BRCA1 heterozygotes in response to UVA although this is not reflected in genomic instability as measured by micronuclei induction after oxidative stress or MMC treatment.
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Affiliation(s)
- Julie Shorrocks
- Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Lancaster LA1 4YQ, UK
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295
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Zhao R, Yang FT, Alexander DR. An oncogenic tyrosine kinase inhibits DNA repair and DNA-damage-induced Bcl-xL deamidation in T cell transformation. Cancer Cell 2004; 5:37-49. [PMID: 14749125 DOI: 10.1016/s1535-6108(03)00333-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A transgenic mouse model of T cell lymphoma was used to investigate the transforming events mediated by an oncogenic tyrosine kinase in pretumorigenic CD4-CD8- (DN) thymocytes. Parental CD45(-/-) and p56(lck-F505Y) mice do not develop tumors, whereas their CD45(-/-)p56(lck-F505Y) progeny develop T lymphomas. Increased but nononcogenic p56lck kinase activity in p56(lck-F505Y) mice DN thymocytes causes cell-cycle progression, survival, and Bcl-XL upregulation. Additional unique oncogenic signals occur in pretumorigenic CD45(-/-)p56(lck-F505Y) thymocytes in which p56lck kinase activity is 2- to 3-fold higher relative to p56(lck-F505Y): inhibition of DNA repair, inhibition of DNA-damage-induced Bcl-XL deamidation, Bax conformational change and mitochondrial translocation, cytochrome c release, and the apoptotic caspase execution cascade. Inhibition of Bcl-XL deamidation may be a critical switch in oncogenic kinase-induced T cell transformation.
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Affiliation(s)
- Rui Zhao
- Laboratory of Lymphocyte Signalling and Development, Molecular Immunology Programme, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK
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296
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Rothfuss A, Grompe M. Repair kinetics of genomic interstrand DNA cross-links: evidence for DNA double-strand break-dependent activation of the Fanconi anemia/BRCA pathway. Mol Cell Biol 2004; 24:123-34. [PMID: 14673148 PMCID: PMC303365 DOI: 10.1128/mcb.24.1.123-134.2004] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2003] [Revised: 09/04/2003] [Accepted: 10/23/2003] [Indexed: 11/20/2022] Open
Abstract
The detailed mechanisms of DNA interstrand cross-link (ICL) repair and the involvement of the Fanconi anemia (FA)/BRCA pathway in this process are not known. Present models suggest that recognition and repair of ICL in human cells occur primarily during the S phase. Here we provide evidence for a refined model in which ICLs are recognized and are rapidly incised by ERCC1/XPF independent of DNA replication. However, the incised ICLs are then processed further and DNA double-strand breaks (DSB) form exclusively in the S phase. FA cells are fully proficient in the sensing and incision of ICL as well as in the subsequent formation of DSB, suggesting a role of the FA/BRCA pathway downstream in ICL repair. In fact, activation of FANCD2 occurs slowly after ICL treatment and correlates with the appearance of DSB in the S phase. In contrast, activation is rapid after ionizing radiation, indicating that the FA/BRCA pathway is specifically activated upon DSB formation. Furthermore, the formation of FANCD2 foci is restricted to a subpopulation of cells, which can be labeled by bromodeoxyuridine incorporation. We therefore conclude that the FA/BRCA pathway, while being dispensable for the early events in ICL repair, is activated in S-phase cells after DSB have formed.
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Affiliation(s)
- Andreas Rothfuss
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon 97239, USA.
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297
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Abstract
An increased mutation rate in human cells is a critical contributing factor for the development of malignancy. Many autosomal recessive genetic disorders are known, in which an increased mutation rate and predisposition for cancer can be attributed to a deficiency in DNA repair or associated processes. Some of these DNA repair deficiencies are manifested at the level of the mitotic chromosome as increased breakage, particularly after treatment with specific mutagens. The examination of the response of cells from patients with these disorders to carcinogens offers the opportunity to elucidate the mechanisms operating in human cells to combat DNA damage and mutation. Over the last few years, the underlying genes in many of these syndromes have been identified, enabling a much more detailed definition of the processes disturbed. This review concentrates on two of the chromosomal breakage syndromes, Fanconi anaemia and Nijmegen breakage syndrome, which have both distinct and common cellular features.
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Affiliation(s)
- Martin Digweed
- Institut für Humangenetik, Charité-Campus Virchow Klinikum, Humboldt Universität zu Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
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298
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Seki M, Marini F, Wood RD. POLQ (Pol theta), a DNA polymerase and DNA-dependent ATPase in human cells. Nucleic Acids Res 2003; 31:6117-26. [PMID: 14576298 PMCID: PMC275456 DOI: 10.1093/nar/gkg814] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2003] [Revised: 09/04/2003] [Accepted: 09/04/2003] [Indexed: 11/14/2022] Open
Abstract
The genomes of eukaryotic cells predict the existence of multiple DNA polymerases, which are proposed to serve specialized roles in DNA replication and repair. We report here the isolation of the full-length human DNA POLQ gene, and an initial characterization of its gene product, DNA polymerase theta. POLQ is of particular interest as it is orthologous to Drosophila Mus308, a gene implicated in cellular resistance to interstrand DNA cross-linking agents. The POLQ cDNA encodes a polypeptide of 2592 amino acids with an ATPase-helicase domain in the N-terminal part of the protein, a central spacer domain, and a DNA polymerase domain in the C-terminal portion. This arrangement is conserved with Mus308. Expression of an mRNA of approximately 8.5 kb was detected in human cell lines. In a survey of human and mouse tissues, expression was highest in testis. Immunoblotting with POLQ antibodies detected a protein of >250 kDa in extracts from HeLa cells. Prominent fragments of approximately 100 kDa suggest that POLQ is readily proteolyzed. Full-length human POLQ was expressed from a baculovirus system. Purified POLQ showed DNA polymerase activity on nicked double-stranded DNA and on a singly primed DNA template. The enzyme activity was resistant to aphidicolin, consistent with its membership of the A family of DNA polymerases, and inhibited by dideoxynucleotides. POLQ further exhibited a single-stranded DNA-dependent ATPase activity.
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Affiliation(s)
- Mineaki Seki
- University of Pittsburgh Cancer Institute, Hillman Cancer Center, Research Pavilion, 5117 Centre Avenue, Suite 2.6, Pittsburgh, PA 15213, USA
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299
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Lage C, de Pádula M, de Alencar TAM, da Fonseca Gonçalves SR, da Silva Vidal L, Cabral-Neto J, Leitão AC. New insights on how nucleotide excision repair could remove DNA adducts induced by chemotherapeutic agents and psoralens plus UV-A (PUVA) in Escherichia coli cells. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2003; 544:143-57. [PMID: 14644316 DOI: 10.1016/j.mrrev.2003.06.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Chemotherapeutic agents such as mitomycin C or nitrogen mustards induce DNA inter-strand cross-links (ICL) and are highly toxic, thus constituting an useful tool to treat some human degenerative diseases, such as cancer. Additionally, psoralens plus UV-A (PUVA), which also induce ICL, find use in treatment of patients afflicted with psoriasis and vitiligo. The repair of DNA ICL generated by different molecules involves a number of multi-step DNA repair pathways. In bacteria, as in eukaryotic cells, if DNA ICL are not tolerated or repaired via nucleotide excision repair (NER), homologous recombination or translesion synthesis pathways, these DNA lesions may lead to mutations and cell death. Herein, we bring new insights to the role of Escherichia coli nucleotide excision repair genes uvrA, uvrB and uvrC in the repair of DNA damage induced by some chemotherapeutic agents and psoralen derivatives plus UV-A. These new observations point to a novel role for the UvrB protein, independent of its previously described role in the Uvr(A)BC complex, which could be specific for repair of monoadducts, intra-strand biadducts and/or ICL.
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Affiliation(s)
- Claudia Lage
- Laboratório de Radiobiologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Bloco G, Centro de Ciencias da Saude, Universidade de Federal do Rio de Janeiro, 21949-900 Rio de Janeiro, RJ, Brazil
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300
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Wachters FM, van Putten JWG, Maring JG, Zdzienicka MZ, Groen HJM, Kampinga HH. Selective targeting of homologous DNA recombination repair by gemcitabine. Int J Radiat Oncol Biol Phys 2003; 57:553-62. [PMID: 12957269 DOI: 10.1016/s0360-3016(03)00503-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE Gemcitabine (2',2'-difluoro-2'-deoxycytidine, dFdC) is a potent radiosensitizer. The mechanism of dFdC-mediated radiosensitization is yet poorly understood. We recently excluded inhibition of DNA double-strand break (DSB) repair by nonhomologous end-joining (NHEJ) as a means of radiosensitization. In the current study, we addressed the possibility that dFdC might affect homologous recombination (HR)-mediated DSB repair or base excision repair (BER). METHODS AND MATERIALS DFdC-mediated radiosensitization in cell lines deficient in BER and in HR was compared with that in their BER-proficient and HR-proficient parental counterparts. Sensitization to mitomycin C (MMC) was also investigated in cell lines deficient and proficient in HR. Additionally, the effect of dFdC on Rad51 foci formation after irradiation was studied. RESULTS DFdC did induce radiosensitization in BER-deficient cells; however, the respective mutant cells deficient in HR did not show dFdC-mediated radiosensitization. In HR-proficient, but not in HR-deficient, cells dFdC also induced substantial enhancement of the cytotoxic effect of MMC. Finally, we found that dFdC interferes with Rad51 foci formation after irradiation. CONCLUSION DFdC causes radiosensitization by specific interference with HR.
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Affiliation(s)
- Floris M Wachters
- Department of Pulmonary Diseases, University Hospital Groningen, Groningen, The Netherlands.
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