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Sarai N, Kagawa W, Fujikawa N, Saito K, Hikiba J, Tanaka K, Miyagawa K, Kurumizaka H, Yokoyama S. Biochemical analysis of the N-terminal domain of human RAD54B. Nucleic Acids Res 2008; 36:5441-50. [PMID: 18718930 PMCID: PMC2553597 DOI: 10.1093/nar/gkn516] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 07/16/2008] [Accepted: 07/29/2008] [Indexed: 01/28/2023] Open
Abstract
The human RAD54B protein is a paralog of the RAD54 protein, which plays important roles in homologous recombination. RAD54B contains an N-terminal region outside the SWI2/SNF2 domain that shares less conservation with the corresponding region in RAD54. The biochemical roles of this region of RAD54B are not known, although the corresponding region in RAD54 is known to physically interact with RAD51. In the present study, we have biochemically characterized an N-terminal fragment of RAD54B, consisting of amino acid residues 26-225 (RAD54B(26-225)). This fragment formed a stable dimer in solution and bound to branched DNA structures. RAD54B(26-225) also interacted with DMC1 in both the presence and absence of DNA. Ten DMC1 segments spanning the entire region of the DMC1 sequence were prepared, and two segments, containing amino acid residues 153-214 and 296-340, were found to directly bind to the N-terminal domain of RAD54B. A structural alignment of DMC1 with the Methanococcus voltae RadA protein, a homolog of DMC1 in the helical filament form, indicated that these RAD54B-binding sites are located near the ATP-binding site at the monomer-monomer interface in the DMC1 helical filament. Thus, RAD54B binding may affect the quaternary structure of DMC1. These observations suggest that the N-terminal domain of RAD54B plays multiple roles of in homologous recombination.
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Affiliation(s)
- Naoyuki Sarai
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Wataru Kagawa
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Norie Fujikawa
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kengo Saito
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Juri Hikiba
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kozo Tanaka
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kiyoshi Miyagawa
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hitoshi Kurumizaka
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shigeyuki Yokoyama
- Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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52
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Wu W, Wang M, Mussfeldt T, Iliakis G. Enhanced Use of Backup Pathways of NHEJ in G2in Chinese Hamster Mutant Cells with Defects in the Classical Pathway of NHEJ. Radiat Res 2008; 170:512-20. [DOI: 10.1667/rr1456.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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53
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Rusin P, Olszewski J, Morawiec-Bajda A, Przybylowska K, Kaczmarczyk D, Golinska A, Majsterek I. Role of impaired DNA repair in genotoxic susceptibility of patients with head and neck cancer. Cell Biol Toxicol 2008; 25:489-97. [PMID: 18787964 DOI: 10.1007/s10565-008-9103-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 08/14/2008] [Indexed: 11/28/2022]
Abstract
DNA repair is critical for genotoxic susceptibility and cancer development. Forty-seven patients with head and neck squamous cell carcinoma (HNSCC) and 38 healthy controls were enrolled in this study. Among the patients, 16 subjects had metastasis of HNSCC. The extent of DNA damage, including oxidative lesions, and efficiency of repair after genotoxic treatment with hydrogen peroxide were examined using the alkaline comet assay. HNSCC cells were sensitive to genotoxic treatment and displayed impaired DNA repair. In particular, lesions caused by hydrogen peroxide were repaired less effectively in cancer cells from patients with metastasis than in cells from healthy controls. We suggest that impaired DNA repair might play a role in genotoxic susceptibility of patients with head and neck cancer. Finally, as a consequence of this finding we have shown that treatment with DNA-reactive drugs could be considered as an effective therapy strategy for head and neck cancer.
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Affiliation(s)
- Pawel Rusin
- Department of Molecular Genetics, University of Lodz, Poland
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54
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Abstract
Hereditary defects in the repair of DNA damage are implicated in a variety of diseases, many of which are typified by neurological dysfunction and/or increased genetic instability and cancer. Of the different types of DNA damage that arise in cells, single-strand breaks (SSBs) are the most common, arising at a frequency of tens of thousands per cell per day from direct attack by intracellular metabolites and from spontaneous DNA decay. Here, the molecular mechanisms and organization of the DNA-repair pathways that remove SSBs are reviewed and the connection between defects in these pathways and hereditary neurodegenerative disease are discussed.
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Affiliation(s)
- Keith W Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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55
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Godon C, Cordelières FP, Biard D, Giocanti N, Mégnin-Chanet F, Hall J, Favaudon V. PARP inhibition versus PARP-1 silencing: different outcomes in terms of single-strand break repair and radiation susceptibility. Nucleic Acids Res 2008; 36:4454-64. [PMID: 18603595 PMCID: PMC2490739 DOI: 10.1093/nar/gkn403] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The consequences of PARP-1 disruption or inhibition on DNA single-strand break repair (SSBR) and radio-induced lethality were determined in synchronized, isogenic HeLa cells stably silenced or not for poly(ADP-ribose) polymerase-1 (PARP-1) (PARP-1KD) or XRCC1 (XRCC1KD). PARP-1 inhibition prevented XRCC1-YFP recruitment at sites of 405 nm laser micro irradiation, slowed SSBR 10-fold and triggered the accumulation of large persistent foci of GFP-PARP-1 and GFP-PCNA at photo damaged sites. These aggregates are presumed to hinder the recruitment of other effectors of the base excision repair (BER) pathway. PARP-1 silencing also prevented XRCC1-YFP recruitment but did not lengthen the lifetime of GFP-PCNA foci. Moreover, PARP-1KD and XRCC1KD cells in S phase completed SSBR as rapidly as controls, while SSBR was delayed in G1. Taken together, the data demonstrate that a PARP-1- and XRCC1-independent SSBR pathway operates when the short patch repair branch of the BER is deficient. Long patch repair is the likely mechanism, as GFP-PCNA recruitment at photo-damaged sites was normal in PARP-1KD cells. PARP-1 silencing elicited hyper-radiosensitivity, while radiosensitization by a PARP inhibitor reportedly occurs only in those cells treated in S phase. PARP-1 inhibition and deletion thus have different outcomes in terms of SSBR and radiosensitivity.
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Affiliation(s)
- Camille Godon
- Institut Curie, Centre de Recherche Inserm, U612, Institut Curie, Bât. 110-112, Centre Universitaire, F-91405 Orsay, France
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56
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Role of Dot1 in the response to alkylating DNA damage in Saccharomyces cerevisiae: regulation of DNA damage tolerance by the error-prone polymerases Polzeta/Rev1. Genetics 2008; 179:1197-210. [PMID: 18562671 DOI: 10.1534/genetics.108.089003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Maintenance of genomic integrity relies on a proper response to DNA injuries integrated by the DNA damage checkpoint; histone modifications play an important role in this response. Dot1 methylates lysine 79 of histone H3. In Saccharomyces cerevisiae, Dot1 is required for the meiotic recombination checkpoint as well as for chromatin silencing and the G(1)/S and intra-S DNA damage checkpoints in vegetative cells. Here, we report the analysis of the function of Dot1 in the response to alkylating damage. Unexpectedly, deletion of DOT1 results in increased resistance to the alkylating agent methyl methanesulfonate (MMS). This phenotype is independent of the dot1 silencing defect and does not result from reduced levels of DNA damage. Deletion of DOT1 partially or totally suppresses the MMS sensitivity of various DNA repair mutants (rad52, rad54, yku80, rad1, rad14, apn1, rad5, rad30). However, the rev1 dot1 and rev3 dot1 mutants show enhanced MMS sensitivity and dot1 does not attenuate the MMS sensitivity of rad52 rev3 or rad52 rev1. In addition, Rev3-dependent MMS-induced mutagenesis is increased in dot1 cells. We propose that Dot1 inhibits translesion synthesis (TLS) by Polzeta/Rev1 and that the MMS resistance observed in the dot1 mutant results from the enhanced TLS activity.
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57
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Chen D, Yu Z, Zhu Z, Lopez CD. E2F1 regulates the base excision repair gene XRCC1 and promotes DNA repair. J Biol Chem 2008; 283:15381-9. [PMID: 18348985 PMCID: PMC2397471 DOI: 10.1074/jbc.m710296200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 03/12/2008] [Indexed: 11/06/2022] Open
Abstract
The E2F1 transcription factor activates S-phase-promoting genes, mediates apoptosis, and stimulates DNA repair through incompletely understood mechanisms. XRCC1 (x-ray repair cross-complementing group 1) protein is important for efficient single strand break/base excision repair. Although both damage and proliferative signals increase XRCC1 levels, the mechanisms regulating XRCC1 transcription remain unclear. To study these upstream mechanisms, the XRCC1 promoter was cloned into a luciferase reporter. Ectopic expression of wild-type E2F1, but not an inactive mutant E2F1(132E), activated the XRCC1 promoter-luciferase reporter, and deletion of predicted E2F1 binding sites in the promoter attenuated E2F1-induced activation. Endogenous XRCC1 expression increased in cells conditionally expressing wild-type, but not mutant E2F1, and methyl methanesulfonate-induced DNA damage stimulated XRCC1 expression in E2F1(+/+) but not E2F1(-/-) mouse embryo fibroblasts (MEFs). Additionally, E2F1(-/-) MEFs displayed attenuated DNA repair after methyl methanesulfonate-induced damage compared with E2F1(+/+) MEFs. Moreover, Chinese hamster ovary cells with mutant XRCC1 (EM9) were more sensitive to E2F1-induced apoptosis compared with Chinese hamster ovary cells with wild-type XRCC1 (AA8). These results provide new mechanistic insight into the role of the E2F pathway in maintaining genomic stability.
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Affiliation(s)
| | | | | | - Charles D. Lopez
- Department of Medicine, Division of Hematology and Medical Oncology, Oregon Health and Science University, Portland, Oregon 97239
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58
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Brasnjevic I, Hof PR, Steinbusch HWM, Schmitz C. Accumulation of nuclear DNA damage or neuron loss: molecular basis for a new approach to understanding selective neuronal vulnerability in neurodegenerative diseases. DNA Repair (Amst) 2008; 7:1087-97. [PMID: 18458001 DOI: 10.1016/j.dnarep.2008.03.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
According to a long-standing hypothesis, aging is mainly caused by accumulation of nuclear (n) DNA damage in differentiated cells such as neurons due to insufficient nDNA repair during lifetime. In line with this hypothesis it was until recently widely accepted that neuron loss is a general consequence of normal aging, explaining some degree of decline in brain function during aging. However, with the advent of more accurate procedures for counting neurons, it is currently widely accepted that there is widespread preservation of neuron numbers in the aging brain, and the changes that do occur are relatively specific to certain brain regions and types of neurons. Whether accumulation of nDNA damage and decline in nDNA repair is a general phenomenon in the aging brain or also shows cell-type specificity is, however, not known. It has not been possible to address this issue with the biochemical and molecular-biological methods available to study nDNA damage and nDNA repair. Rather, it was the introduction of autoradiographic methods to study quantitatively the relative amounts of nDNA damage (measured as nDNA single-strand breaks) and nDNA repair (measured as unscheduled DNA synthesis) on tissue sections that made it possible to address this question in a cell-type-specific manner under physiological conditions. The results of these studies revealed a formerly unknown inverse relationship between age-related accumulation of nDNA damage and age-related impairment in nDNA repair on the one hand, and the age-related, selective, loss of neurons on the other hand. This inverse relation may not only reflect a fundamental process of aging in the central nervous system but also provide the molecular basis for a new approach to understand the selective neuronal vulnerability in neurodegenerative diseases, particularly Alzheimer's disease.
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Affiliation(s)
- Ivona Brasnjevic
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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59
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Altieri F, Grillo C, Maceroni M, Chichiarelli S. DNA damage and repair: from molecular mechanisms to health implications. Antioxid Redox Signal 2008; 10:891-937. [PMID: 18205545 DOI: 10.1089/ars.2007.1830] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
DNA is subjected to several modifications, resulting from endogenous and exogenous sources. The cell has developed a network of complementary DNA-repair mechanisms, and in the human genome, >130 genes have been found to be involved. Knowledge about the basic mechanisms for DNA repair has revealed an unexpected complexity, with overlapping specificity within the same pathway, as well as extensive functional interactions between proteins involved in repair pathways. Unrepaired or improperly repaired DNA lesions have serious potential consequences for the cell, leading to genomic instability and deregulation of cellular functions. A number of disorders or syndromes, including several cancer predispositions and accelerated aging, are linked to an inherited defect in one of the DNA-repair pathways. Genomic instability, a characteristic of most human malignancies, can also arise from acquired defects in DNA repair, and the specific pathway affected is predictive of types of mutations, tumor drug sensitivity, and treatment outcome. Although DNA repair has received little attention as a determinant of drug sensitivity, emerging knowledge of mutations and polymorphisms in key human DNA-repair genes may provide a rational basis for improved strategies for therapeutic interventions on a number of tumors and degenerative disorders.
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Affiliation(s)
- Fabio Altieri
- Department of Biochemical Sciences, A. Rossi Fanelli, University La Sapienza, Rome, Italy.
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60
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O'Driscoll M, Jeggo PA. CsA can induce DNA double-strand breaks: implications for BMT regimens particularly for individuals with defective DNA repair. Bone Marrow Transplant 2008; 41:983-9. [DOI: 10.1038/bmt.2008.18] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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61
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Rosidi B, Wang M, Wu W, Sharma A, Wang H, Iliakis G. Histone H1 functions as a stimulatory factor in backup pathways of NHEJ. Nucleic Acids Res 2008; 36:1610-23. [PMID: 18250087 PMCID: PMC2275134 DOI: 10.1093/nar/gkn013] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
DNA double-strand breaks (DSBs) induced in the genome of higher eukaryotes by ionizing radiation (IR) are predominantly removed by two pathways of non-homologous end-joining (NHEJ) termed D-NHEJ and B-NHEJ. While D-NHEJ depends on the activities of the DNA-dependent protein kinase (DNA-PK) and DNA ligase IV/XRCC4/XLF, B-NHEJ utilizes, at least partly, DNA ligase III/XRCC1 and PARP-1. Using in vitro end-joining assays and protein fractionation protocols similar to those previously applied for the characterization of DNA ligase III as an end-joining factor, we identify here histone H1 as an additional putative NHEJ factor. H1 strongly enhances DNA-end joining and shifts the product spectrum from circles to multimers. While H1 enhances the DNA-end-joining activities of both DNA Ligase IV and DNA Ligase III, the effect on ligase III is significantly stronger. Histone H1 also enhances the activity of PARP-1. Since histone H1 has been shown to counteract D-NHEJ, these observations and the known functions of the protein identify it as a putative alignment factor operating preferentially within B-NHEJ.
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Affiliation(s)
- Bustanur Rosidi
- University of Duisburg-Essen, Medical School, Institute of Medical Radiation Biology, 45122 Essen, Germany
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62
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CHIP-Mediated Degradation and DNA Damage-Dependent Stabilization Regulate Base Excision Repair Proteins. Mol Cell 2008; 29:477-87. [DOI: 10.1016/j.molcel.2007.12.027] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 08/24/2007] [Accepted: 12/03/2007] [Indexed: 11/24/2022]
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63
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Wu W, Wang M, Wu W, Singh SK, Mussfeldt T, Iliakis G. Repair of radiation induced DNA double strand breaks by backup NHEJ is enhanced in G2. DNA Repair (Amst) 2008; 7:329-38. [DOI: 10.1016/j.dnarep.2007.11.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 01/20/2023]
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64
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Grigoryan RS, Yang B, Keshelava N, Barnhart JR, Reynolds CP. Flow cytometry analysis of single-strand DNA damage in neuroblastoma cell lines using the F7-26 monoclonal antibody. Cytometry A 2008; 71:951-60. [PMID: 17879237 DOI: 10.1002/cyto.a.20458] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The F7-26 monoclonal antibody (Mab) has been reported to be specific for single-strand DNA damage (ssDNA) and to also identify cells in apoptosis. We carriedout studies to determine if F7-26 binding measured by flow cytometry was able to specifically identify exogenous ssDNA as opposed to DNA damage from apoptosis. Neuroblastoma cells were treated with melphalan (L-PAM), fenretinide, 4-hydroperoxycyclophosphamide (4-HC)+/-pan-caspase inhibitor BOC-d-fmk, topotecan or with 10Gy gamma radiation+/-hydrogen peroxide (H2O2) and fixed immediately postradiation. Cytotoxicity was measured by DIMSCAN digital imaging fluorescence assay. The degree of ssDNA damage was analyzed by flow cytometry using Mab F7-26, with DNA visualized by propidium iodide counterstaining. Flow cytometry was used to measure apoptosis detected by terminal deoxynucleotidyltransferase (TUNEL) assay and reactive oxygen species (ROS) by carboxy-dichlorofluorescein diacetate. Irradiated and immediately fixed neuroblastoma cells showed increased ssDNA, but not apoptosis by TUNEL (TUNEL-negative). 4-HC or L-PAM+/-BOC-d-fmk increased ssDNA (F7-26-positive), but BOC-d-fmk prevented TUNEL staining. Fenretinide increased apoptosis by TUNEL but not ssDNA damage detected with F7-26. Enhanced ssDNA in neuroblastoma cells treated with radiation+H2O2 was associated with increased ROS. Topotecan increased both ssDNA and cytotoxicity in 4-HC-treated cells. These data demonstrate that Mab F7-26 recognized ssDNA due to exogenous DNA damage, rather than apoptosis. This assay should be useful to characterize the mechanism of action of antineoplastic drugs.
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Affiliation(s)
- Rita S Grigoryan
- Developmental Therapeutics Program, USC-CHLA Institute for Pediatric Clinical Research, Los Angeles, California 90027, USA
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65
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Windhofer F, Wu W, Iliakis G. Low levels of DNA ligases III and IV sufficient for effective NHEJ. J Cell Physiol 2008; 213:475-83. [PMID: 17492771 DOI: 10.1002/jcp.21120] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cells of higher eukaryotes rejoin double strand breaks (DSBs) in their DNA predominantly by a non-homologous DNA end joining (NHEJ) pathway that utilizes the products of DNA-PKcs, Ku, LIG4, XRCC4, XLF/Cernunnos, Artemis as well as DNA polymerase lambda (termed D-NHEJ). Mutants with defects in these proteins remove a large proportion of DSBs from their genome utilizing an alternative pathway of NHEJ that operates as a backup (B-NHEJ). While D-NHEJ relies exclusively on DNA ligase IV, recent work points to DNA ligase III as a component of B-NHEJ. Here, we use RNA interference (RNAi) to further investigate the activity requirements for DNA ligase III and IV in the pathways of NHEJ. We report that 70-80% knock down of LIG3 expression has no detectable effect on DSB rejoining, either in D-NHEJ proficient cells, or in cells where D-NHEJ has been chemically or genetically compromised. Surprisingly, also LIG4 knock down has no effect on repair proficient cells, but inhibits DSB rejoining in a radiosensitive cell line with a hypomorphic LIG4 mutation that severely compromises its activity. The results suggest that complete coverage for D-NHEJ or B-NHEJ is afforded by very low ligase levels and demonstrate residual end joining by DNA ligase IV in cells of patients with mutations in LIG4.
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Affiliation(s)
- Frank Windhofer
- Institute of Medical Radiation Biology, University Duisburg-Essen Medical School, Essen, Germany
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66
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Takahashi T, Tada M, Igarashi S, Koyama A, Date H, Yokoseki A, Shiga A, Yoshida Y, Tsuji S, Nishizawa M, Onodera O. Aprataxin, causative gene product for EAOH/AOA1, repairs DNA single-strand breaks with damaged 3'-phosphate and 3'-phosphoglycolate ends. Nucleic Acids Res 2007; 35:3797-809. [PMID: 17519253 PMCID: PMC1920238 DOI: 10.1093/nar/gkm158] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Aprataxin is the causative gene product for early-onset ataxia with ocular motor apraxia and hypoalbuminemia/ataxia with oculomotor apraxia type 1 (EAOH/AOA1), the clinical symptoms of which are predominantly neurological. Although aprataxin has been suggested to be related to DNA single-strand break repair (SSBR), the physiological function of aprataxin remains to be elucidated. DNA single-strand breaks (SSBs) continually produced by endogenous reactive oxygen species or exogenous genotoxic agents, typically possess damaged 3′-ends including 3′-phosphate, 3′-phosphoglycolate, or 3′-α, β-unsaturated aldehyde ends. These damaged 3′-ends should be restored to 3′-hydroxyl ends for subsequent repair processes. Here we demonstrate by in vitro assay that recombinant human aprataxin specifically removes 3′-phosphoglycolate and 3′-phosphate ends at DNA 3′-ends, but not 3′-α, β-unsaturated aldehyde ends, and can act with DNA polymerase β and DNA ligase III to repair SSBs with these damaged 3′-ends. Furthermore, disease-associated mutant forms of aprataxin lack this removal activity. The findings indicate that aprataxin has an important role in SSBR, that is, it removes blocking molecules from 3′-ends, and that the accumulation of unrepaired SSBs with damaged 3′-ends underlies the pathogenesis of EAOH/AOA1. The findings will provide new insight into the mechanism underlying degeneration and DNA repair in neurons.
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Affiliation(s)
- Tetsuya Takahashi
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Masayoshi Tada
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Shuichi Igarashi
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Akihide Koyama
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Hidetoshi Date
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Akio Yokoseki
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Atsushi Shiga
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Yutaka Yoshida
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Shoji Tsuji
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Masatoyo Nishizawa
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
| | - Osamu Onodera
- Department of Neurology, Clinical Neuroscience Branch, Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-Based Research, Brain Research Institute, Department of Structural Pathology Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757 Asahimachi, Niigata 951-8122, Japan and Department of Neurology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo113-8655, Japan
- *To whom correspondence should be addressed. 81 25 227 066581 25 223 6646
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Richter T, Saretzki G, Nelson G, Melcher M, Olijslagers S, von Zglinicki T. TRF2 overexpression diminishes repair of telomeric single-strand breaks and accelerates telomere shortening in human fibroblasts. Mech Ageing Dev 2007; 128:340-5. [PMID: 17395247 DOI: 10.1016/j.mad.2007.02.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 02/14/2007] [Accepted: 02/28/2007] [Indexed: 12/21/2022]
Abstract
Repair of single strand breaks in telomeric DNA is less efficient than in other genomic regions. This leads to an increased vulnerability of telomeric DNA towards damage induced by reactive oxygen species (ROS) and to accelerated telomere shortening under oxidative stress. The causes for the diminished repair efficacy in telomeres are unknown. We show here that overexpression of the telomere-binding protein TRF2 further reduces telomeric, but not genomic, single strand break repair. This suggests the possibility of strand break repair in telomeres being sterically hindered by the three-dimensional structure of the telomere DNA-protein complex and explains the effect of TRF2 on telomere shortening rates in telomerase-negative cells.
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Affiliation(s)
- Torsten Richter
- Henry Wellcome Biogerontology Laboratory and Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, University of Newcastle upon Tyne, UK
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Abstract
Mutations in the Aptx gene lead to a neurological disorder known as ataxia oculomotor apraxia-1. The product of Aptx is Aprataxin (Aptx), a DNA-binding protein that resolves abortive DNA ligation intermediates. Aprataxin catalyzes the nucleophilic release of adenylate groups covalently linked to 5' phosphate termini, resulting in termini that can again serve as substrates for DNA ligases. Here we show that Aprataxin acts preferentially on adenylated nicks and double-strand breaks rather than on single-stranded DNA. Moreover, we show that whereas the catalytic activity of Aptx resides within the HIT domain, the C-terminal zinc finger domain provides stabilizing contacts that lock the enzyme onto its high affinity AMP-DNA target site. Both domains are therefore required for efficient AMP-DNA hydrolase activity. Additionally, we find a role for Aprataxin in base excision repair, specifically in the removal of adenylates that arise from abortive ligation reactions that take place at incised abasic sites in DNA. We suggest that Aprataxin may have a general proofreading function in DNA repair, removing DNA adenylates as they arise during single-strand break repair, double-strand break repair, and in base excision repair.
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Affiliation(s)
- Ulrich Rass
- Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, United Kingdom
| | - Ivan Ahel
- Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, United Kingdom
| | - Stephen C West
- Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, United Kingdom.
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69
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Parlanti E, Locatelli G, Maga G, Dogliotti E. Human base excision repair complex is physically associated to DNA replication and cell cycle regulatory proteins. Nucleic Acids Res 2007; 35:1569-77. [PMID: 17289756 PMCID: PMC1865045 DOI: 10.1093/nar/gkl1159] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
It has been hypothesized that a replication associated repair pathway operates on base damage and single strand breaks (SSB) at replication forks. In this study, we present the isolation from the nuclei of human cycling cells of a multiprotein complex containing most of the essential components of base excision repair (BER)/SSBR, including APE1, UNG2, XRCC1 and POLβ, DNA PK, replicative POLα, δ and ɛ, DNA ligase 1 and cell cycle regulatory protein cyclin A. Co-immunoprecipitation revealed that in this complex DNA repair proteins are physically associated to cyclin A and to DNA replication proteins including MCM7. This complex is endowed with DNA polymerase and protein kinase activity and is able to perform BER of uracil and AP sites. This finding suggests that a preassembled DNA repair machinery is constitutively active in cycling cells and is ready to be recruited at base damage and breaks occurring at replication forks.
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Affiliation(s)
- Eleonora Parlanti
- Department of Environment and Primary Prevention, Section of Molecular Epidemiology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy and DNA Enzymology and Molecular Virology, Istituto di Genetica Molecolare, IGM-CNR, National Research Council, Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Giada Locatelli
- Department of Environment and Primary Prevention, Section of Molecular Epidemiology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy and DNA Enzymology and Molecular Virology, Istituto di Genetica Molecolare, IGM-CNR, National Research Council, Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Giovanni Maga
- Department of Environment and Primary Prevention, Section of Molecular Epidemiology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy and DNA Enzymology and Molecular Virology, Istituto di Genetica Molecolare, IGM-CNR, National Research Council, Via Abbiategrasso 207, 27100 Pavia, Italy
- *To whom correspondence should be addressed. (+39) 0382546354(+39) 0382422286
| | - Eugenia Dogliotti
- Department of Environment and Primary Prevention, Section of Molecular Epidemiology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy and DNA Enzymology and Molecular Virology, Istituto di Genetica Molecolare, IGM-CNR, National Research Council, Via Abbiategrasso 207, 27100 Pavia, Italy
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70
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Prise KM, Burdak-Rothkamm S, Folkard M, Kashino G, Shao C, Tartier L. New insights on radiation-induced bystander signalling and its relationship to DNA repair. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.ics.2006.10.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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71
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Rutten BPF, Schmitz C, Gerlach OHH, Oyen HM, de Mesquita EB, Steinbusch HWM, Korr H. The aging brain: Accumulation of DNA damage or neuron loss? Neurobiol Aging 2007; 28:91-8. [PMID: 16338029 DOI: 10.1016/j.neurobiolaging.2005.10.019] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 10/25/2005] [Accepted: 10/27/2005] [Indexed: 12/22/2022]
Abstract
Age-related molecular and cellular alterations in the central nervous system are known to show selectivity for certain cell types and brain regions. Among them age-related accumulation of nuclear (n) DNA damage can lead to irreversible loss of genetic information content. In the present study on the aging mouse brain, we observed a substantial increase in the amount of nDNA single-strand breaks in hippocampal pyramidal and granule cells as well as in cerebellar granule cells but not in cerebellar Purkinje cells. The reverse pattern was found for age-related reductions in total numbers of neurons. Only the total number of cerebellar Purkinje cells was significantly reduced during aging whereas the total numbers of hippocampal pyramidal and granule cells as well as of cerebellar granule cells were not. This formerly unknown inverse relation between age-related accumulation of nDNA damage and age-related loss of neurons may reflect a fundamental process of aging in the central nervous system.
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Affiliation(s)
- Bart P F Rutten
- Department of Psychiatry and Neuropsychology, Division of Cellular Neuroscience, Maastricht University, Universiteitssingel 50, 6200 MD Maastricht, The Netherlands
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72
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Nazarkina ZK, Khodyreva SN, Marsin S, Lavrik OI, Radicella JP. XRCC1 interactions with base excision repair DNA intermediates. DNA Repair (Amst) 2006; 6:254-64. [PMID: 17118717 DOI: 10.1016/j.dnarep.2006.10.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 10/09/2006] [Accepted: 10/12/2006] [Indexed: 01/21/2023]
Abstract
Abasic (AP) sites in DNA arise either spontaneously, or through glycosylase-catalyzed excision of damaged bases. Their removal by the base excision repair (BER) pathway avoids their mutagenic and cytotoxic consequences. XRCC1 coordinates and facilitates single-strand break (SSB) repair and BER in mammalian cells. We report that XRCC1, through its NTD and BRCT1 domains, has affinity for several DNA intermediates in BER. As shown by its capacity to form a covalent complex via Schiff base, XRCC1 binds AP sites. APE1 suppresses binding of XRCC1 to unincised AP sites however, affinity was higher when the DNA carried an AP-lyase- or APE1-incised AP site. The AP site binding capacity of XRCC1 is enhanced by the presence of strand interruptions in the opposite strand. Binding of XRCC1 to BER DNA intermediates could play an important role to warrant the accurate repair of damaged bases, AP sites or SSBs, in particular in the context of clustered DNA damage.
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Affiliation(s)
- Zhanna K Nazarkina
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Prospect Lavrentieva 8, Novosibirsk 630090, Russia
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73
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Wang M, Wu W, Wu W, Rosidi B, Zhang L, Wang H, Iliakis G. PARP-1 and Ku compete for repair of DNA double strand breaks by distinct NHEJ pathways. Nucleic Acids Res 2006; 34:6170-82. [PMID: 17088286 PMCID: PMC1693894 DOI: 10.1093/nar/gkl840] [Citation(s) in RCA: 596] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Poly(ADP-ribose)polymerase 1 (PARP-1) recognizes DNA strand interruptions in vivo and triggers its own modification as well as that of other proteins by the sequential addition of ADP-ribose to form polymers. This modification causes a release of PARP-1 from DNA ends and initiates a variety of responses including DNA repair. While PARP-1 has been firmly implicated in base excision and single strand break repair, its role in the repair of DNA double strand breaks (DSBs) remains unclear. Here, we show that PARP-1, probably together with DNA ligase III, operates in an alternative pathway of non-homologous end joining (NHEJ) that functions as backup to the classical pathway of NHEJ that utilizes DNA-PKcs, Ku, DNA ligase IV, XRCC4, XLF/Cernunnos and Artemis. PARP-1 binds to DNA ends in direct competition with Ku. However, in irradiated cells the higher affinity of Ku for DSBs and an excessive number of other forms of competing DNA lesions limit its contribution to DSB repair. When essential components of the classical pathway of NHEJ are absent, PARP-1 is recruited for DSB repair, particularly in the absence of Ku and non-DSB lesions. This form of DSB repair is sensitive to PARP-1 inhibitors. The results define the function of PARP-1 in DSB repair and characterize a candidate pathway responsible for joining errors causing genomic instability and cancer.
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Affiliation(s)
| | | | | | | | | | - Huichen Wang
- Center for Neurovirology, Temple University1900 North 12th, Philadelphia, PA 19122, USA
| | - George Iliakis
- To whom correspondence should be addressed. Tel: +49 201 723 4152; Fax: +49 201 723 5966;
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Abstract
At least four disorders, ataxia telangiectasia (AT), an ataxia-telangiectasia-like disorder, early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ ataxia with oculomotor apraxia type 1 (AOA1), and ataxia with oculomotor apraxia type 2, are accompanied by ocular motor apraxia (OMA), which is an impairment of saccadic eye movement initiation. The characteristic pathological findings of EAOH/AOA1 and AT are a severe loss of Purkinje cells, severe myelin pallor of the posterior columns, and moderate neuronal loss in the dorsal root ganglia and anterior horn. Purkinje cells stimulate the fastigial nucleus and suppress omnipause neurons to initiate saccadic eye movement. The selective loss of Purkinje cells might cause OMA and disturb the cancellation of the vestibulo-ocular reflex. These disorders have the following common clinical features: ataxia, involuntary movements, and peripheral neuronopathy. In addition, the causative genes for these disorders are associated with the DNA/RNA quality control system. The impairment of DNA/ RNA integrity results in selective neuronal loss in these recessive-inherited ataxias.
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Affiliation(s)
- Osamu Onodera
- Department of Molecular Neuroscience, Resource Branch for Brain Disease, Brain Research Institute, Niigata University, Japan.
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Sarai N, Kagawa W, Kinebuchi T, Kagawa A, Tanaka K, Miyagawa K, Ikawa S, Shibata T, Kurumizaka H, Yokoyama S. Stimulation of Dmc1-mediated DNA strand exchange by the human Rad54B protein. Nucleic Acids Res 2006; 34:4429-37. [PMID: 16945962 PMCID: PMC1636354 DOI: 10.1093/nar/gkl562] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The process of homologous recombination is indispensable for both meiotic and mitotic cell division, and is one of the major pathways for double-strand break (DSB) repair. The human Rad54B protein, which belongs to the SWI2/SNF2 protein family, plays a role in homologous recombination, and may function with the Dmc1 recombinase, a meiosis-specific Rad51 homolog. In the present study, we found that Rad54B enhanced the DNA strand-exchange activity of Dmc1 by stabilizing the Dmc1–single-stranded DNA (ssDNA) complex. Therefore, Rad54B may stimulate the Dmc1-mediated DNA strand exchange by stabilizing the nucleoprotein filament, which is formed on the ssDNA tails produced at DSB sites during homologous recombination.
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Affiliation(s)
- Naoyuki Sarai
- RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Wataru Kagawa
- RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Takashi Kinebuchi
- RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Ako Kagawa
- RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
| | - Kozo Tanaka
- School of Life Sciences, University of Dundee, Wellcome Trust BiocentreDundee DD1 5EH, UK
| | - Kiyoshi Miyagawa
- Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shukuko Ikawa
- RIKEN Discovery Research Institute, Wako-shiSaitama 351-0198, Japan
| | - Takehiko Shibata
- RIKEN Discovery Research Institute, Wako-shiSaitama 351-0198, Japan
| | - Hitoshi Kurumizaka
- RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
- Graduate School of Science and Engineering, Waseda University3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
- To whom correspondence should be addressed. Tel: +81 3 5286 8189; Fax: +81 3 5292 9211;
| | - Shigeyuki Yokoyama
- RIKEN Genomic Sciences Center1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- RIKEN Harima Institute at SPring-8, 1-1-1 KohtoMikazuki-cho, Sayo, Hyogo 679-5148, Japan
- Correspondence may also be addressed to Shigeyuki Yokoyama. Tel: +81 3 5841 4413; Fax: +81 3 5841 8057;
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Sunderland PA, West CE, Waterworth WM, Bray CM. An evolutionarily conserved translation initiation mechanism regulates nuclear or mitochondrial targeting of DNA ligase 1 in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 47:356-67. [PMID: 16790030 DOI: 10.1111/j.1365-313x.2006.02791.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The Arabidopsis DNA ligase 1 gene (AtLIG1) is indispensable for cell viability. AtLIG1 expresses one major and two minor mRNA transcripts differing only in the length of the 5' untranslated leader sequences preceding a common ORF. Control of AtLIG1 isoform production and intracellular targeting depends upon mechanisms controlling the choice of translation initiation site within the AtLIG1 ORF. Confocal laser scanning microscopy of green fluorescent protein-tagged AtLIG1 isoforms expressed in Arabidopsis revealed that translation of AtLIG1 mRNA transcripts from the first in-frame start codon produces an AtLIG1 isoform that is targeted exclusively to the mitochondria. Translation initiation from the second in-frame start codon produces an AtLIG1 isoform targeted only to the nucleus. There is no evidence for AtLIG1-GFP being targeted to chloroplasts. The mitochondrial AtLIG1 isoform possesses both an N-terminal mitochondrial-targeting signal and an internal bipartite nuclear localization signal (NLS) yet is targeted only to mitochondria, demonstrating a hierarchical dominance of the mitochondrial presequence over the NLS. The length of the 5'-UTR and more significantly the nucleotide context around alternative start codons in the AtLIG1 transcripts affect translation initiation to ensure a balanced synthesis of both nuclear and mitochondrial AtLIG1 isoforms, probably via a context-dependent leaky ribosome scanning mechanism.
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Affiliation(s)
- Paul A Sunderland
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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77
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Jiao L, Bondy ML, Hassan MM, Wolff RA, Evans DB, Abbruzzese JL, Li D. Selected polymorphisms of DNA repair genes and risk of pancreatic cancer. ACTA ACUST UNITED AC 2006; 30:284-91. [PMID: 16844323 PMCID: PMC1857309 DOI: 10.1016/j.cdp.2006.05.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2006] [Indexed: 01/19/2023]
Abstract
BACKGROUND Genetic variants of DNA repair genes may contribute to pancreatic carcinogenesis. O(6)-methylguanine-DNA methyltransferase (MGMT) is the major protein that removes alkylating DNA adducts, and apurinic/apyrimidinic endonuclease 1 (APE1) and X-ray repair cross-complementing group 1 (XRCC1) play important roles in the base excision repair pathway. METHODS We investigated the association between polymorphisms of MGMT (Leu(84)Phe and Ile(143)Val), APE1 (Asp(148)Glu), and XRCC1 (Arg(194)Trp and Arg(399)Gln) and risk of pancreatic cancer in a case-control study. Exposure information from 384 patients with primary pancreatic ductal adenocarcinoma and 357 cancer-free healthy controls were collected and genomic DNAs were genotyped for five markers. Controls were frequency matched to patients by age at enrollment (+/-5 years), gender, and race. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) by using unconditional logistic regression models. RESULTS There was no significant main effect or interaction with smoking of these genetic variants on the risk of pancreatic cancer. However, the XRCC1(194) polymorphism had a significant interaction with the APE1(148) (p=0.005) or MGMT(84) polymorphism (p=0.02) in modifying the risk of pancreatic cancer. CONCLUSIONS This study suggests that polymorphisms of genes involved in the repair of alkylating DNA adduct and DNA base damage may play a role in modulating the risk of pancreatic cancer. Larger studies are required to validate these preliminary findings. The mechanism of the combined genotype effects remains to be elucidated.
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Affiliation(s)
- Li Jiao
- Department of Gastrointestinal Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
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Prise KM, Folkard M, Kuosaite V, Tartier L, Zyuzikov N, Shao C. What role for DNA damage and repair in the bystander response? Mutat Res 2006; 597:1-4. [PMID: 16414091 DOI: 10.1016/j.mrfmmm.2005.06.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Accepted: 06/03/2005] [Indexed: 05/06/2023]
Abstract
The radiation-induced bystander effect challenges the accepted paradigm of direct DNA damage in response to energy deposition driving the biological consequences of radiation exposure. With the bystander response, cells which have not been directly exposed to radiation respond to their neighbours being targeted. In our own studies we have used novel targeted microbeam approaches to specifically irradiate parts of individual cells within a population to quantify the bystander response and obtain mechanistic information. Using this approach it has become clear that energy deposited by radiation in nuclear DNA is not required to trigger the effect, with cytoplasmic irradiation required. Irradiated cells also trigger a bystander response regardless of whether they themselves live or die, suggesting that the phenotype of the targeted cell is not a determining factor. Despite this however, a range of evidence has shown that repair status is important for dealing with the consequences of a bystander signal. Importantly, repair processes involved in the processing of dsb appear to be involved suggesting that the bystander response involves the delayed or indirect production of dsb-type lesions in bystander cells. Whether these are infact true dsb or complexes of oxidised bases in combination with strand breaks and the mechanisms for their formation, remains to be elucidated.
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Affiliation(s)
- Kevin M Prise
- Gray Cancer Institute, PO Box 100, Mount Vernon Hospital, Northwood, Middlesex HA6 2JR, UK.
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79
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Puebla-Osorio N, Lacey DB, Alt FW, Zhu C. Early embryonic lethality due to targeted inactivation of DNA ligase III. Mol Cell Biol 2006; 26:3935-41. [PMID: 16648486 PMCID: PMC1489003 DOI: 10.1128/mcb.26.10.3935-3941.2006] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 12/21/2005] [Accepted: 03/02/2006] [Indexed: 11/20/2022] Open
Abstract
DNA ligases catalyze the joining of strand breaks in the phosphodiester backbone of duplex DNA and play essential roles in DNA replication, recombination, repair, and maintenance of genomic integrity. Three mammalian DNA ligase genes have been identified, and their corresponding ligases play distinct roles in DNA metabolism. DNA ligase III is proposed to be involved in the repairing of DNA single-strand breaks, but its precise role has not yet been demonstrated directly. To determine its role in DNA repair, cellular growth, and embryonic development, we introduced targeted interruption of the DNA ligase III (LIG3) gene into the mouse. Mice homozygous for LIG3 disruption showed early embryonic lethality. We found that the mutant embryonic developmental process stops at 8.5 days postcoitum (dpc), and excessive cell death occurs at 9.5 dpc. LIG3 mutant cells have relatively normal XRCC1 levels but elevated sister chromatid exchange. These findings indicate that DNA ligase III is involved in essential DNA repair activities required for early embryonic development and therefore cannot be replaced by other DNA ligases.
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Affiliation(s)
- Nahum Puebla-Osorio
- Department of Immunology, Unit 902, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, Texas 77030, USA
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80
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Thyagarajan B, Anderson KE, Folsom AR, Jacobs DR, Lynch CF, Bargaje A, Khaliq W, Gross MD. No association between XRCC1 and XRCC3 gene polymorphisms and breast cancer risk: Iowa Women's Health Study. ACTA ACUST UNITED AC 2006; 30:313-21. [PMID: 16963196 DOI: 10.1016/j.cdp.2006.07.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2006] [Indexed: 12/01/2022]
Abstract
BACKGROUND Genetic variation in DNA repair may contribute to differences in the susceptibility of several cancers. We evaluated two polymorphisms in the base excision repair pathway (BER) (XRCC1; Arg194Trp and Arg399Gln) and one polymorphism in the double strand DNA repair pathway (XRCC3; Thr241Met) for their association with breast cancer risk. METHODS The association was analyzed in a nested case control study of 460 breast cancer cases and 324 cancer-free controls within the Iowa Women's Health Cohort. DNA was obtained from blood samples or paraffin embedded tissues (PET) and all samples were genotyped by one of three genotyping platforms-PCR-RFLP, PCR-INVADER, or Sequenom. RESULTS None of the three polymorphisms studied were significantly associated with breast cancer risk (XRCC1: Arg194Trp (OR=1.21, 95% CI: 0.78-1.88); Arg399Gln (OR=1.20, 95% CI: 0.80-1.79); XRCC3: Thr241Met (OR=1.04, 95% CI: 0.76-1.41). CONCLUSIONS These results suggest that independently these polymorphisms of XRCC1 and XRCC3 genes do not contribute significantly to the genetic susceptibility of breast cancer.
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Affiliation(s)
- Bharat Thyagarajan
- University of Minnesota, Division of Epidemiology, Suite 300, West Bank Office Building, Minneapolis, MN 55454, United States
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81
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Boiteux S, Guillet M. Use of yeast for detection of endogenous abasic lesions, their source, and their repair. Methods Enzymol 2006; 408:79-91. [PMID: 16793364 DOI: 10.1016/s0076-6879(06)08006-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Apurinic/apyrimidinic (AP) sites are expected to be one of the most frequent endogenous lesions in DNA. AP sites are potentially lethal and mutagenic. Data shows that the simultaneous inactivation of two AP endonucleases (Apn1 and Apn2) and of the nuclease Rad1-Rad10 causes cell death in Saccharomyces cerevisiae. We suggest that the essential function of Apn1, Apn2, and Rad1-Rad10 is to repair endogenous AP sites and related 3'-blocked single strand breaks. This data led us to conclude that the burden of endogenous AP sites is not compatible with life in absence of DNA repair. This chapter describes two genetic assays to investigate origin, repair, and biological consequences of endogenous AP sites in yeast. The first assay relies on genetic crosses and tetrad analysis and uses the apn1 apn2 rad1 triple mutant. The apn1 apn2 rad1 triple mutant is unviable; however, it can form microcolonies. By means of genetic crosses, apn1 apn2 rad1 x quadruple mutants are generated. The size of the colonies formed by each quadruple mutant is compared to that of the apn1 apn2 rad1 triple mutant. Three classes of genes (x) were identified: (i) genes whose inactivation aggravates the phenotype (reduces microcolony size), such as RAD9, RAD50, RAD51, RAD52, MUS81, and MRE11; (ii) genes whose inactivation alleviates the phenotype, such as UNG1, NTG1, and NTG2; and (iii) genes whose inactivation is neutral, such as MAG1 or OGG1. The second assay uses the apn1 apn2 rad14 triple mutant, which is viable but exhibits a spontaneous mutator phenotype. This mutant was used in a colethal screen. This assay allowed the identification of mutation in DNA repair genes such as RAD1 or RAD50, as well as a mutation in the DUT1 gene coding for the dUTPase, which has impact on the formation of AP sites in DNA. A model that summarizes our present and puzzling data on the origin and repair of endogenous AP sites is also presented.
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Affiliation(s)
- Serge Boiteux
- Laboratory of Radiobiology DNA, Department of Radiobiology and Radiopathology, Aus Roses, France
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82
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Parsons JL, Dianova II, Boswell E, Weinfeld M, Dianov GL. End-damage-specific proteins facilitate recruitment or stability of X-ray cross-complementing protein 1 at the sites of DNA single-strand break repair. FEBS J 2005; 272:5753-63. [PMID: 16279940 DOI: 10.1111/j.1742-4658.2005.04962.x] [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: 11/29/2022]
Abstract
Ionizing radiation, oxidative stress and endogenous DNA-damage processing can result in a variety of single-strand breaks with modified 5' and/or 3' ends. These are thought to be one of the most persistent forms of DNA damage and may threaten cell survival. This study addresses the mechanism involved in recognition and processing of DNA strand breaks containing modified 3' ends. Using a DNA-protein cross-linking assay, we followed the proteins involved in the repair of oligonucleotide duplexes containing strand breaks with a phosphate or phosphoglycolate group at the 3' end. We found that, in human whole cell extracts, end-damage-specific proteins (apurinic/apyrimidinic endonuclease 1 and polynucleotide kinase in the case of 3' ends containing phosphoglycolate and phosphate, respectively) which recognize and process 3'-end-modified DNA strand breaks are required for efficient recruitment of X-ray cross-complementing protein 1-DNA ligase IIIalpha heterodimer to the sites of DNA repair.
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83
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Bray CM, West CE. DNA repair mechanisms in plants: crucial sensors and effectors for the maintenance of genome integrity. THE NEW PHYTOLOGIST 2005; 168:511-28. [PMID: 16313635 DOI: 10.1111/j.1469-8137.2005.01548.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
As obligate phototrophs, plants harness energy from sunlight to split water, producing oxygen and reducing power. This lifestyle exposes plants to particularly high levels of genotoxic stress that threatens genomic integrity, leading to mutation, developmental arrest and cell death. Plants, which with algae are the only photosynthetic eukaryotes, have evolved very effective pathways for DNA damage signalling and repair, and this review summarises our current understanding of these processes in the responses of plants to genotoxic stress. We also identify how the use of new and emerging technologies can complement established physiological and ecological studies to progress the application of this knowledge in biotechnology.
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Affiliation(s)
- Clifford M Bray
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
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84
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Theron T, Fousteri MI, Volker M, Harries LW, Botta E, Stefanini M, Fujimoto M, Andressoo JO, Mitchell J, Jaspers NGJ, McDaniel LD, Mullenders LH, Lehmann AR. Transcription-associated breaks in xeroderma pigmentosum group D cells from patients with combined features of xeroderma pigmentosum and Cockayne syndrome. Mol Cell Biol 2005; 25:8368-78. [PMID: 16135823 PMCID: PMC1234319 DOI: 10.1128/mcb.25.18.8368-8378.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Defects in the XPD gene can result in several clinical phenotypes, including xeroderma pigmentosum (XP), trichothiodystrophy, and, less frequently, the combined phenotype of XP and Cockayne syndrome (XP-D/CS). We previously showed that in cells from two XP-D/CS patients, breaks were introduced into cellular DNA on exposure to UV damage, but these breaks were not at the sites of the damage. In the present work, we show that three further XP-D/CS patients show the same peculiar breakage phenomenon. We show that these breaks can be visualized inside the cells by immunofluorescence using antibodies to either gamma-H2AX or poly-ADP-ribose and that they can be generated by the introduction of plasmids harboring methylation or oxidative damage as well as by UV photoproducts. Inhibition of RNA polymerase II transcription by four different inhibitors dramatically reduced the number of UV-induced breaks. Furthermore, the breaks were dependent on the nucleotide excision repair (NER) machinery. These data are consistent with our hypothesis that the NER machinery introduces the breaks at sites of transcription initiation. During transcription in UV-irradiated XP-D/CS cells, phosphorylation of the carboxy-terminal domain of RNA polymerase II occurred normally, but the elongating form of the polymerase remained blocked at lesions and was eventually degraded.
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Affiliation(s)
- Therina Theron
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom
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85
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86
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Liu X, Guo Y, Li Y, Jiang Y, Chubb S, Azuma A, Huang P, Matsuda A, Hittelman W, Plunkett W. Molecular Basis for G2Arrest Induced by 2′-C-Cyano-2′-Deoxy-1-β-d-Arabino-Pentofuranosylcytosine and Consequences of Checkpoint Abrogation. Cancer Res 2005; 65:6874-81. [PMID: 16061671 DOI: 10.1158/0008-5472.can-05-0288] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
2'-C-cyano-2'-deoxy-1-beta-D-arabino-pentofuranosylcytosine (CNDAC) is a nucleoside analogue with a novel mechanism of action that is currently being evaluated in clinical trials. Incorporation of CNDAC triphosphate into DNA and extension during replication leads to single-strand breaks directly caused by beta-elimination. These breaks, or the lesions that arise from further processing, cause cells to arrest in G2. The purpose of this investigation was to define the molecular basis for G2 checkpoint activation and to delineate the sequelae of its abrogation. Cell lines derived from diverse human tissues underwent G2 arrest after CNDAC treatment, suggesting a common mechanism of response to the damage created. CNDAC-induced G2 arrest was instituted by activation of the Chk1-Cdc25C-Cdk1/cyclin B checkpoint pathway. Neither Chk2, p38, nor p53 was required for checkpoint activation. Inhibition of Chk1 kinase with 7-hydroxystaurosporine (UCN-01) abrogated the checkpoint pathway as indicated by dephosphorylation of checkpoint proteins and progression of cells through mitosis and into G1. Cell death was first evident in hematologic cell lines after G1 entry. As indicated by histone H2AX phosphorylation, DNA damage initiated by CNDAC incorporation was transformed into double-strand breaks when ML-1 cells arrested in G2. Some breaks were manifested as chromosomal aberrations when the G2 checkpoint of CNDAC-arrested cells was abrogated by UCN-01 but also in a minor population of cells that escaped to mitosis during treatment with CNDAC alone. These findings provide a mechanistic rationale for the design of new strategies, combining CNDAC with inhibitors of cell cycle checkpoint regulation in the therapy of hematologic malignancies.
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Affiliation(s)
- Xiaojun Liu
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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87
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Neijenhuis S, Begg AC, Vens C. Radiosensitization by a dominant negative to DNA polymerase β is DNA polymerase β-independent and XRCC1-dependent. Radiother Oncol 2005; 76:123-8. [PMID: 16024118 DOI: 10.1016/j.radonc.2005.06.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Revised: 05/13/2005] [Accepted: 06/19/2005] [Indexed: 11/17/2022]
Abstract
BACKGROUND AND PURPOSE DNA base damages and single strand breaks after ionizing radiation are repaired by base excision repair (BER) and single strand break repair (SSBR), with both DNA polymerase beta (polbeta) and XRCC1 playing key roles. We previously showed that a dominant negative to polbeta (polbetaDN) sensitized human tumor cells to ionizing radiation. However, polbeta-deficient cells, in contrast to XRCC1-deficient cells, are not more radiosensitive. The purpose of the present study was to further elucidate the mechanism of action of the polbetaDN to better understand the roles of BER and SSBR in determining radiosensitivity. MATERIALS AND METHODS Mouse embryonic fibroblasts, both polbeta wildtype and knockout, and hamster XRCC1-deficient EM9 cells together with its parental line, were transfected with the polbetaDN. Clones with equal polbetaDN expression levels were selected and used in clonogenic assays to determine radiosensitivity. RESULTS Radiosensitization of polbeta deficient cells by the polbetaDN is shown here, demonstrating inhibition of a polbeta-independent pathway. In addition, we observed radiosensitization of wildtype hamster cells but no radiosensitization of the XRCC1-deficient EM9 cells. CONCLUSIONS The polbetaDN acts independently of polbeta status and inhibits a pathway, which is dependent on XRCC1, consistent with inhibition of BER and/or SSBR. The data further indicate involvement of other polymerases, which are inhibited by polbetaDN. Finally, they demonstrate that inhibition of BER and SSBR can increase radiosensitivity, with potential clinical relevance.
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Affiliation(s)
- Sari Neijenhuis
- Division of Experimental Therapy, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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88
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Vidaković M, Poznanović G, Bode J. DNA break repair: refined rules of an already complicated game. Biochem Cell Biol 2005; 83:365-73. [PMID: 15959562 DOI: 10.1139/o05-044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Of the many types of DNA-damage repair, this review concentrates on the aspects of DNA single- and double-strand break repair. Originally considered to represent separate routes based on distinct enzymatic machineries, it has recently been shown that these pathways converge and are interlinked at a number of points. Poly(ADP-ribose) polymerase-1 (PARP-1) is a central player in this complicated game. We present new data and our view on the mechanisms by which PARP-1 is guided to its respective interaction partners to coordinate or participate in repair or apoptosis.Key words: DNA strand break repair (DSBR), non-homologous end joining (NHEJ), nuclear architecture, nuclear matrix, PARP-1.
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Affiliation(s)
- Melita Vidaković
- Molecular Biology Laboratory, Institute for Biological Research, Belgrade, Serbia and Montenegro
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89
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Rinne ML, He Y, Pachkowski BF, Nakamura J, Kelley MR. N-methylpurine DNA glycosylase overexpression increases alkylation sensitivity by rapidly removing non-toxic 7-methylguanine adducts. Nucleic Acids Res 2005; 33:2859-67. [PMID: 15905475 PMCID: PMC1131935 DOI: 10.1093/nar/gki601] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Previous studies indicate that overexpression of N-methylpurine DNA glycosylase (MPG) dramatically sensitizes cells to alkylating agent-induced cytotoxicity. We recently demonstrated that this sensitivity is preceded by an increased production of AP sites and strand breaks, confirming that overexpression of MPG disrupts normal base excision repair and causes cell death through overproduction of toxic repair intermediates. Here we establish through site-directed mutagenesis that MPG-induced sensitivity to alkylation is dependent on enzyme glycosylase activity. However, in contrast to the sensitivity seen to heterogeneous alkylating agents, MPG overexpression generates no cellular sensitivity to MeOSO2(CH2)2-lexitropsin, an alkylator which exclusively induces 3-meA lesions. Indeed, MPG overexpression has been shown to increase the toxicity of alkylating agents that produce 7-meG adducts, and here we demonstrate that MPG-overexpressing cells have dramatically increased removal of 7-meG from their DNA. These data suggest that the mechanism of MPG-induced cytotoxicity involves the conversion of non-toxic 7-meG lesions into highly toxic repair intermediates. This study establishes a mechanism by which a benign DNA modification can be made toxic through the overexpression of an otherwise well-tolerated gene product, and the application of this principle could lead to improved chemotherapeutic strategies that reduce the peripheral toxicity of alkylating agents.
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Affiliation(s)
- M. L. Rinne
- Department of Biochemistry and Molecular Biology, Indiana University School of MedicineIndianapolis, IN 46202, USA
| | - Y. He
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of MedicineIndianapolis, IN 46202, USA
| | - B. F. Pachkowski
- Department of Environmental Sciences and Engineering, School of Public Health, University of North CarolinaChapel Hill, NC 27599, USA
| | - J. Nakamura
- Department of Environmental Sciences and Engineering, School of Public Health, University of North CarolinaChapel Hill, NC 27599, USA
| | - M. R. Kelley
- Department of Biochemistry and Molecular Biology, Indiana University School of MedicineIndianapolis, IN 46202, USA
- Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of MedicineIndianapolis, IN 46202, USA
- Department of Pharmacology and Toxicology, Indiana University School of MedicineIndianapolis, IN 46202, USA
- To whom correspondence should be addressed. Tel: +1 317 274 2755; Fax: +1 317 278 9298;
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90
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Tell G, Damante G, Caldwell D, Kelley MR. The intracellular localization of APE1/Ref-1: more than a passive phenomenon? Antioxid Redox Signal 2005; 7:367-84. [PMID: 15706084 DOI: 10.1089/ars.2005.7.367] [Citation(s) in RCA: 291] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Human apurinic/apyrimidinic endonuclease 1/redox effector factor-1 (APE1/Ref-1) is a perfect paradigm of the functional complexity of a biological macromolecule. First, it plays a crucial role, by both redox-dependent and -independent mechanisms, as a transcriptional coactivator for different transcription factors, either ubiquitous (i.e., AP-1, Egr-1, NF-kappaB, p53, HIF) or tissue-specific (i.e., PEBP-2, Pax-5 and -8, TTF-1), in controlling different cellular processes such as apoptosis, proliferation, and differentiation. Second, it acts, as an apurinic/apyrimidinic endonuclease, during the second step of the DNA base excision repair pathway, which is responsible for the repair of cellular alkylation and oxidative DNA damages. Third, it controls the intracellular reactive oxygen species production by negatively regulating the activity of the Ras-related GTPase Rac1. Despite these known functions of APE1/Ref-1, information is still scanty about the molecular mechanisms responsible for the coordinated control of its several activities. Some evidence suggests that the expression and subcellular localization of APE1/Ref-1 are finely tuned. APE1/Ref-1 is a ubiquitous protein, but its expression pattern differs according to the different cell types. APE1/Ref-1 subcellular localization is mainly nuclear, but cytoplasmic staining has also been reported, the latter being associated with mitochondria and/or presence within the endoplasmic reticulum. It is not by chance that both expression and subcellular localization are altered in several metabolic and proliferative disorders, such as in tumors and aging. Moreover, a fundamental role played by different posttranslational modifications in modulating APE1/Ref-1 functional activity is becoming evident. In the present review, we tried to put together a growing body of information concerning APE1/Ref-1's different functions, shedding new light on present and future directions to understand fully this unique molecule.
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Affiliation(s)
- Gianluca Tell
- Department of Biomedical Sciences and Technologies, University of Udine, Piazzale Kolbe 4, 33100 Udine, Italy.
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91
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Akerman GS, Rosenzweig BA, Domon OE, Tsai CA, Bishop ME, McGarrity LJ, Macgregor JT, Sistare FD, Chen JJ, Morris SM. Alterations in gene expression profiles and the DNA-damage response in ionizing radiation-exposed TK6 cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2005; 45:188-205. [PMID: 15657912 DOI: 10.1002/em.20091] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Identifying genes that are differentially expressed in response to DNA damage may help elucidate markers for genetic damage and provide insight into the cellular responses to specific genotoxic agents. We utilized cDNA microarrays to develop gene expression profiles for ionizing radiation-exposed human lymphoblastoid TK6 cells. In order to relate changes in the expression profiles to biological responses, the effects of ionizing radiation on cell viability, cloning efficiency, and micronucleus formation were measured. TK6 cells were exposed to 0.5, 1, 5, 10, and 20 Gy ionizing radiation and cultured for 4 or 24 hr. A significant (P < 0.0001) decrease in cloning efficiency was observed at all doses at 4 and 24 hr after exposure. Flow cytometry revealed significant decreases in cell viability at 24 hr in cells exposed to 5 (P < 0.001), 10 (P < 0.0001), and 20 Gy (P < 0.0001). An increase in micronucleus frequency occurred at both 4 and 24 hr at 0.5 and 1 Gy; however, insufficient binucleated cells were present for analysis at the higher doses. Gene expression profiles were developed from mRNA isolated from cells exposed to 5, 10, and 20 Gy using a 350 gene human cDNA array platform. Overall, more genes were differentially expressed at 24-hr than at the 4-hr time point. The genes upregulated (> 1.5-fold) or downregulated (< 0.67-fold) at 4 hr were those primarily involved in the cessation of the cell cycle, cellular detoxification pathways, DNA repair, and apoptosis. At 24 hr, glutathione-associated genes were induced in addition to genes involved in apoptosis. Genes involved in cell cycle progression and mitosis were downregulated at 24 hr. Real-time quantitative PCR was used to confirm the microarray results and to evaluate expression levels of selected genes at the low doses (0.5 and 1.0 Gy). The expression profiles reflect the cellular and molecular responses to ionizing radiation related to the recognition of DNA damage, a halt in progression through the cell cycle, activation of DNA-repair pathways, and the promotion of apoptosis.
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Affiliation(s)
- Gregory S Akerman
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079, USA
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92
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Shen J, Gammon MD, Terry MB, Wang L, Wang Q, Zhang F, Teitelbaum SL, Eng SM, Sagiv SK, Gaudet MM, Neugut AI, Santella RM. Polymorphisms in XRCC1 Modify the Association between Polycyclic Aromatic Hydrocarbon-DNA Adducts, Cigarette Smoking, Dietary Antioxidants, and Breast Cancer Risk. Cancer Epidemiol Biomarkers Prev 2005; 14:336-42. [PMID: 15734955 DOI: 10.1158/1055-9965.epi-04-0414] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The variability in DNA repair capacity of the general population may depend in part upon common variants in DNA repair genes. X-ray repair cross complementing group 1 (XRCC1) is an important DNA base excision repair gene and exhibits polymorphic variation. Using the Long Island Breast Cancer Study Project, a population-based case-control study, we evaluated the hypothesis that two common single nucleotide polymorphisms of XRCC1 (codon 194 Arg-->Trp and 399 Arg-->Gln) influence breast cancer susceptibility and interact with polycyclic aromatic hydrocarbon (PAH)-DNA adducts, cigarette smoking, and intake of fruits and vegetables and antioxidants. The available sample for genotyping included 1,067 cases and 1,110 controls. Genotyping was done by a high-throughput single-nucleotide extension assay with fluorescence polarization detection of the incorporated nucleotide. We observed no significant increases in risk among all subjects who were carriers of XRCC1 194Trp or 399Gln alleles. Among never smokers, we observed an increased risk of breast cancer in 399Gln carriers [odds ratio (OR), 1.3; 95% confidence interval (CI), 1.0-1.7). Further analysis indicated a suggestive weak additive interaction between the 399Gln allele and detectable PAH-DNA adducts (OR for exposure with mutant genotype, 1.9; 95% CI, 1.2-3.1). The estimated age-adjusted interaction contrast ratio (ICR) and 95% CI (ICR, 0.38; 95% CI, -0.32 to 1.10) indicated that the departure from additivity was not statistically significant, but that there was some suggestion of a relative excess risk due to the interaction. In subjects with at least one copy of XRCC1 194Trp allele, there was a moderate interaction with high intake of fruits and vegetables (>/=35 half-cup servings per week of any fruits, fruit juices, and vegetables, OR, 0.58; 95% CI, 0.38-0.89; ICR, -0.49; 95% CI, -0.03 to -0.95), and dietary plus supplement antioxidant intake with 33% to 42% decreases in breast cancer risk compared with those with the Arg194Arg genotype and low-intake individuals. These results do not show that the two genetic polymorphisms of XRCC1 independently influence breast cancer risk. However, there is evidence for interactions between the two XRCC1 single nucleotide polymorphisms and PAH-DNA adducts or fruit and vegetable and antioxidant intake on breast cancer risk. Further understanding of the biological function of XRCC1 variants and their interactions with PAH-DNA adducts, antioxidants, and other genes in the pathway are needed.
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Affiliation(s)
- Jing Shen
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA.
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93
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Karumbati AS, Wilson TE. Abrogation of the Chk1-Pds1 checkpoint leads to tolerance of persistent single-strand breaks in Saccharomyces cerevisiae. Genetics 2005; 169:1833-44. [PMID: 15687272 PMCID: PMC1449591 DOI: 10.1534/genetics.104.035931] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In budding yeast, Apn1, Apn2, Tpp1, and Rad1/Rad10 are important enzymes in the removal of spontaneous DNA lesions. apn1 apn2 rad1 yeast are inviable due to accumulation of abasic sites and strand breaks with 3' blocking lesions. We found that tpp1 apn1 rad1 yeast exhibited slow growth but frequently gave rise to spontaneous slow growth suppressors that segregated as single-gene mutations. Using a candidate gene approach, we identified several tpp1 apn1 rad1 suppressors. Deleting uracil glycosylase suppressed both tpp1 apn1 rad1 and apn1 apn2 rad1 growth defects by reducing the abasic site burden. Mutants affecting the Chk1-Pds1 metaphase-anaphase checkpoint only suppressed tpp1 apn1 rad1 slow growth. In contrast, most S-phase checkpoint mutants were synthetically lethal in a tpp1 apn1 rad1 background. Epistasis analyses showed an additive effect between chk1 and ung1, indicating different mechanisms of suppression. Loss of Chk1 partially restored cell-growth parameters in tpp1 apn1 rad1 yeast, but at the same time exacerbated chromosome instability. We propose a model in which recombinational repair during S phase coupled with failure of the metaphase-anaphase checkpoint allows for tolerance of persistent single-strand breaks at the expense of genome stability.
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Affiliation(s)
- Anandi S Karumbati
- Department of Pathology, University of Michigan Medical School, Ann Arbor, 48109-0602, USA
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94
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Sossou M, Flohr-Beckhaus C, Schulz I, Daboussi F, Epe B, Radicella JP. APE1 overexpression in XRCC1-deficient cells complements the defective repair of oxidative single strand breaks but increases genomic instability. Nucleic Acids Res 2005; 33:298-306. [PMID: 15647512 PMCID: PMC546158 DOI: 10.1093/nar/gki173] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
XRCC1 protein is essential for mammalian viability and is required for the efficient repair of single strand breaks (SSBs) and damaged bases in DNA. XRCC1-deficient cells are genetically unstable and sensitive to DNA damaging agents. XRCC1 has no known enzymatic activity and is thought to act as a scaffold protein for both SSB and base excision repair activities. To further define the defects leading to genetic instability in XRCC1-deficient cells, we overexpressed the AP endonuclease APE1, shown previously to interact with and be stimulated by XRCC1. Here, we report that the overexpression of APE1 can compensate for the impaired capability of XRCC1-deficient cells to repair SSBs induced by oxidative DNA damage, both in vivo and in whole-cell extracts. We show that, for this kind of damage, the repair of blocked DNA ends is rate limiting and can be performed by APE1. Conversely, APE1 overproduction resulted in a 3-fold increase in the sensitivity of XRCC1-deficient cells to an alkylating agent, most probably due to the accumulation of SSBs. Finally, the overproduction of APE1 results in increases of 40% in the frequency of micronuclei and 33% in sister chromatid exchanges of XRCC1− cells. These data suggest that the spontaneous generation of AP sites could be at the origin of the SSBs responsible for the spontaneous genetic instability characteristic of XRCC1-deficient cells.
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Affiliation(s)
| | | | - Ina Schulz
- Institute of Pharmacy, University of MainzD-55128 Mainz, Germany
| | | | - Bernd Epe
- Institute of Pharmacy, University of MainzD-55128 Mainz, Germany
| | - J. Pablo Radicella
- To whom correspondence should be addressed. Tel: +33 1 46 54 88 57; Fax: +33 1 46 54 88 59;
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95
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Pascucci B, Russo MT, Crescenzi M, Bignami M, Dogliotti E. The accumulation of MMS-induced single strand breaks in G1 phase is recombinogenic in DNA polymerase beta defective mammalian cells. Nucleic Acids Res 2005; 33:280-8. [PMID: 15647510 PMCID: PMC546155 DOI: 10.1093/nar/gki168] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
DNA polymerase (Pol) beta null mouse embryonic fibroblasts provide a useful cell system to investigate the effects of alterations in base excision repair (BER) on genome stability. These cells are characterized by hypersensitivity to the cytotoxic effects of methyl methanesulfonate (MMS) and by decreased repair of the MMS-induced DNA single strand breaks (SSB). Here, we show that, in the absence of Pol beta, SSB accumulate in G1 phase cells, accompanied by the formation of proliferating cell nuclear antigen foci in the nuclei. When replicating Pol beta null cells are treated with MMS, a rapid phosphorylation of histone H2AX is detected in the nuclei of S phase cells, indicating that double strand breaks (DSB) are formed in response to unrepaired SSB. This is followed by relocalization within the nuclei of Rad51 protein, which is essential for homologous recombination (HR). These findings are compatible with a model where, in mammalian cells, unrepaired SSB produced during BER are substrates for the HR pathway via DSB formation. This is an example of a coordinated effort of two different repair pathways, BER and HR, to protect mammalian cells from alkylation-induced cytotoxicity.
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Affiliation(s)
- Barbara Pascucci
- Istituto di Cristallografia, CNR, Sezione di RomaPO Box 10, 00016 Monterotondo Stazione, Roma, Italy
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Roma, Italy
| | - Maria Teresa Russo
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Roma, Italy
| | - Marco Crescenzi
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Roma, Italy
| | - Margherita Bignami
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Roma, Italy
| | - Eugenia Dogliotti
- Department of Environment and Primary Prevention, Istituto Superiore di SanitàViale Regina Elena 299, 00161 Roma, Italy
- To whom correspondence should be addressed. Tel: +39 06 49902580; Fax: +39 06 49903650;
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96
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Audebert M, Salles B, Calsou P. Involvement of Poly(ADP-ribose) Polymerase-1 and XRCC1/DNA Ligase III in an Alternative Route for DNA Double-strand Breaks Rejoining. J Biol Chem 2004; 279:55117-26. [PMID: 15498778 DOI: 10.1074/jbc.m404524200] [Citation(s) in RCA: 510] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The efficient repair of DNA double-strand breaks (DSBs) is critical for the maintenance of genomic integrity. In mammalian cells, the nonhomologous end-joining process that represents the predominant repair pathway relies on the DNA-dependent protein kinase (DNA-PK) and the XRCC4-DNA ligase IV complex. Nonetheless, several in vitro and in vivo results indicate that mammalian cells use more than a single end-joining mechanism. While searching for a DNA-PK-independent end-joining activity, we found that the pretreatment of DNA-PK-proficient and -deficient rodent cells with an inhibitor of the poly(ADP-ribose) polymerase-1 enzyme (PARP-1) led to increased cytotoxicity of the highly efficient DNA double-strand breaking compound calicheamicin gamma1. In addition, the repair kinetics of the DSBs induced by calicheamicin gamma1 was delayed both in PARP-1-proficient cells pretreated with the PARP-1 inhibitor and in PARP-1-deficient cells. In order to get new insights into the mechanism of an alternative route for DSBs repair, we have established a new synapsis and end-joining two-step assay in vitro, operating on DSBs with either nuclear protein extracts or recombinant proteins. We found an end-joining activity independent of the DNA-PK/XRCC4-ligase IV complex but that actually required a novel synapsis activity of PARP-1 and the ligation activity of the XRCC1-DNA ligase III complex, proteins otherwise involved in the base excision repair pathway. Taken together, these results strongly suggest that a PARP-1-dependent DSBs end-joining activity may exist in mammalian cells. We propose that this mechanism could act as an alternative route of DSBs repair that complements the DNA-PK/XRCC4/ligase IV-dependent nonhomologous end-joining.
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Affiliation(s)
- Marc Audebert
- Institut de Pharmacologie et de Biologie Structurale, CNRS UMR 5089, 205 route de Narbonne, F-31077 Toulouse Cedex, France
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97
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Noé V, Peñuelas S, Lamuela-Raventós RM, Permanyer J, Ciudad CJ, Izquierdo-Pulido M. Epicatechin and a cocoa polyphenolic extract modulate gene expression in human Caco-2 cells. J Nutr 2004; 134:2509-16. [PMID: 15465739 DOI: 10.1093/jn/134.10.2509] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We performed a functional genomic analysis to study the effect of epicatechin and polyphenolic cocoa extract in the human colon adenocarcinoma cell line Caco-2. The specific Human Hematology/Immunology cDNA arrays by Clontech, containing 406 genes in duplicate, were used. The differentially expressed genes were classified according to their level of expression, calculated as the ratio of the value obtained after each treatment relative to control cells, with a statistical significance of P < 0.05 (upregulated: ratio > 1.5; downregulated: ratio < 0.6). Treatment with epicatechin decreased the expression of 21 genes and upregulated 24 genes. Upon incubation with the cocoa polyphenolic extract, 24 genes were underexpressed and 28 were overexpressed. The changes in expression for ferritin heavy polypeptide 1 (FTH1), mitogen-activated protein kinase kinase 1 (MAPKK1), signal transducer and activator of transcription 1 (STAT1), and topoisomerase 1 upon incubation with epicatechin, and for myeloid leukemia factor 2 (MLF2), CCAAT/enhancer binding protein gamma (C/EBPG), MAPKK1, ATP-binding cassette, subfamily c member 1 (MRP1), STAT1, topoisomerase 1, and x-ray repair complementing defective repair 1 (XRCC1) upon incubation with the cocoa polyphenolic extract were validated by RT-PCR. Changes in the messenger RNA levels for MAPKK1, STAT1, MRP1, and topoisomerase 1 upon incubation with either epicatechin or cocoa extract were further confirmed at the protein level by Western blotting. The changes in the expression of STAT1, MAPKK1, MRP1, and FTH1 genes, which are involved in the cellular response to oxidative stress, are in agreement with the antioxidant properties of cocoa flavonoids. In addition, the changes in the expression of C/EBPG, topoisomerase 1, MLF2, and XRCC1 suggest novel mechanisms of action of flavonoids at the molecular level.
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Affiliation(s)
- Véronique Noé
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, E-08028 Barcelona, Spain.
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98
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Abstract
The association of human genetic disorders with defects in the DNA damage response is well established. Most of the major DNA repair pathways are represented by diseases in which that pathway is absent or impaired, including those responsible for repairing DNA double-strand breaks. Conspicuous by their absence, however, have been human disorders associated with defects in the repair or response to DNA single-strand breaks (SSBs). However, three papers have recently associated hereditary spinocerebellar ataxia with mutations in genes connected with SSBR. The emerging links between SSBR and neurodegeneration are discussed.
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Affiliation(s)
- Keith W Caldecott
- Genome Damage and Stability Centre, University of Sussex, Science Park Road, Falmer, Brighton BN1 9RQ, UK.
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99
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Li L, Berger SH, Wyatt MD. Involvement of base excision repair in response to therapy targeted at thymidylate synthase. Mol Cancer Ther 2004. [DOI: 10.1158/1535-7163.747.3.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Thymidylate synthase (TS) is an important target of several classes of chemotherapeutic agents. Although the precise mechanism of cytotoxicity in thymidylate deprivation remains obscure, uracil misincorporation and DNA strand breaks are recognized as important events during thymidylate deprivation. Base excision repair (BER) plays a primary role in removing damaged or modified bases from the genome, including uracil. Because of uracil misincorporation, BER is hypothesized to play a role in the cellular response to thymidylate deprivation. In this study, we used murine embryo fibroblasts wild-type or homozygous null for DNA polymerase β (β-pol), which plays a central role in BER. We found that, compared with wild-type, β-pol null cells were resistant to the toxic effects of raltitrexed (Tomudex, ZD1694), a folate inhibitor of TS. There was little difference in TS levels or in TS-ligand complex formation between the cell lines. Furthermore, cells deficient in XRCC1, a scaffold protein for the final steps of BER, were also modestly resistant to raltitrexed compared with XRCC1-proficient cells. Cell cycle analysis revealed that the responses of the wild-type and β-pol null cells were similar during drug exposure. However, following drug removal, the β-pol null cells appeared to resume cell cycle progression more rapidly than the wild-type cells. The results suggest that BER plays a role in modulating the toxic effects of TS inhibitors, and that this role occurs during recovery from TS inhibition.
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Affiliation(s)
- Li Li
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Sondra H. Berger
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Michael D. Wyatt
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
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100
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Inoue M, Shen GP, Chaudhry MA, Galick H, Blaisdell JO, Wallace SS. Expression of the oxidative base excision repair enzymes is not induced in TK6 human lymphoblastoid cells after low doses of ionizing radiation. Radiat Res 2004; 161:409-17. [PMID: 15038771 DOI: 10.1667/3163] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Most of the DNA damage produced by ionizing radiation is repaired by the base excision repair (BER) pathway. To determine whether the BER genes were up-regulated by low doses of ionizing radiation, we investigated their expression in TK6 human lymphoblastoid cells by measuring mRNA levels using real-time quantitative PCR. No induction at the transcriptional level of any of the base excision repair genes, NTH1 (NTHL1), OGG1, NEIL1, NEIL2, NEIL3, APE1, POLB, or accessory protein genes, LIG3, XRCC1 or XPG, was found at gamma-radiation doses ranging from 1 cGy to 2 Gy in a 24-h period. As has been measured in other cell lines, a dose-dependent induction of CDKN1A (WAF1) mRNA levels was observed in TK6 cells in the dose range of 0.5 to 2.0 Gy. We also examined BER enzyme activity on 8-oxoguanine-, dihydrouracil- and furan-containing oligonucleotide substrates and found no increase in extracts of TK6 cells after gamma-ray doses of 0.5-2.0 Gy. These data were corroborated by Western blot analysis of APE1 and NTH1, suggesting that the BER enzymes are also not up-regulated at the post-transcriptional level after ionizing radiation exposure.
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Affiliation(s)
- M Inoue
- Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, The University of Vermont, Burlington, Vermont 05405-0068, USA
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