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Lerner LK, Moreno NC, Rocha CRR, Munford V, Santos V, Soltys DT, Garcia CCM, Sarasin A, Menck CFM. XPD/ERCC2 mutations interfere in cellular responses to oxidative stress. Mutagenesis 2020; 34:341-354. [PMID: 31348825 DOI: 10.1093/mutage/gez020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 07/10/2019] [Indexed: 01/28/2023] Open
Abstract
Nucleotide excision repair (NER) is a conserved, flexible mechanism responsible for the removal of bulky, helix-distorting DNA lesions, like ultraviolet damage or cisplatin adducts, but its role in the repair of lesions generated by oxidative stress is still not clear. The helicase XPD/ERCC2, one of the two helicases of the transcription complex IIH, together with XPB, participates both in NER and in RNA pol II-driven transcription. In this work, we investigated the responses of distinct XPD-mutated cell lines to the oxidative stress generated by photoactivated methylene blue (MB) and KBrO3 treatments. The studied cells are derived from patients with XPD mutations but expressing different clinical phenotypes, including xeroderma pigmentosum (XP), XP and Cockayne syndrome (XP-D/CS) and trichothiodystrophy (TTD). We show by different approaches that all XPD-mutated cell lines tested were sensitive to oxidative stress, with those from TTD patients being the most sensitive. Host cell reactivation (HCR) assays showed that XP-D/CS and TTD cells have severely impaired repair capacity of oxidised lesions in plasmid DNA, and alkaline comet assays demonstrated the induction of significantly higher amounts of DNA strand breaks after treatment with photoactivated MB in these cells compared to wild-type cells. All XPD-mutated cells presented strong S/G2 arrest and persistent γ-H2AX staining after photoactivated MB treatment. Taken together, these results indicate that XPD participates in the repair of lesions induced by the redox process, and that XPD mutations lead to differences in the response to oxidatively induced damage.
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Affiliation(s)
- Leticia K Lerner
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Natália C Moreno
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Clarissa R R Rocha
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Veridiana Munford
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Valquíria Santos
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Daniela T Soltys
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Camila C M Garcia
- Department of Biological Sciences, Federal University of Ouro Preto, Ouro Preto, MG, Brazil
| | - Alain Sarasin
- CNRS-UMR8200, Institut Gustave Roussy, Université Paris-Sud, Villejuif, France
| | - Carlos F M Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
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Protective Effect of JXT Ethanol Extract on Radiation-Induced Hematopoietic Alteration and Oxidative Stress in the Liver. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:9017835. [PMID: 30510630 PMCID: PMC6230390 DOI: 10.1155/2018/9017835] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/01/2018] [Accepted: 09/04/2018] [Indexed: 01/22/2023]
Abstract
This study aims at investigating the radioprotective effect of ethanol extract from Ji-Xue-Teng (JXT, Spatholobus suberectus) on radiation-induced hematopoietic alteration and oxidative stress in the liver. Mice were exposed to a single acute γ-radiation for the whole body at the dose of 6.0 Gy, then subjected to administration of amifostine (45 mg/kg) or JXT (40 g crude drug/kg) once a day for 28 consecutive days, respectively. Bone marrow cells and hemogram including white cells, red cells, platelet counts, and hemoglobin level were examined. The protein expression levels of pJAK2/JAK2, pSTAT5a/STAT5a, pSTAT5b/STAT5b, and Bcl-2 in bone marrow tissue; levels of reactive oxygen species (ROS); and the activity of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in serum and liver tissue were determined. At the end of the experiment, the effect of JXT on cell viability and G-CSF and G-CSFR levels in NFS-60 cells were tested by CCK-8 assay, ELISA, and flow cytometry. The results showed that the mice exposed to γ-radiation alone exhibited a typical hematopoietic syndrome. In contrast, at the end of the 28-day experiment, irradiated mice subjected to oral administration of JXT showed an obvious improvement on blood profile with reduced leucopenia, thrombocytopenia (platelet counts), RBC, and hemoglobin levels, as well as bone marrow cells. The expression of pJAK2/JAK2, pSTAT5a/STAT5a, and Bcl-2 in bone marrow tissue was increased after JXT treatment. The elevation of ROS was due to radiation-induced toxicity, but JXT significantly reduced the ROS level in serum and liver tissue, elevated endogenous SOD and GSH-PX levels, and reduced the MDA level in the liver. JXT could also increase cell viability and G-CSFR level in NFS-60 cells, which was similar to exogenous G-CSF. Our findings suggested that oral administration of JXT effectively facilitated the recovery of hematopoietic bone marrow damage and oxidative stress of the mice induced by γ-radiation.
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Abdel-Magied N, Ahmed AG, Abo Zid N. Possible ameliorative effect of aqueous extract of date (Phoenix dactylifera) pits in rats exposed to gamma radiation. Int J Radiat Biol 2018; 94:815-824. [PMID: 29969364 DOI: 10.1080/09553002.2018.1492165] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE To evaluate the radioprotective efficacy of date (Phoenix dactylifera) pits extract (DPE) against γ-irradiation-induced liver damage in the male albino rats. For this study, 30-day survival, dose reduction factor (DRF), antioxidant status and some biochemical changes in the serum and hepatic tissue were evaluated. MATERIALS AND METHODS To calculate 30-day survival, median lethal dose of 30 days (LD50/30) and DRF, DPE was orally administered to rats for 21 days before irradiation with different doses (5, 6, 8, 10 and 12 Gy) of γ-rays and the rats were observed for 30 days post-irradiation. To evaluate the radioprotective efficacy of DPE against γ-irradiation induced-liver tissue damage, animals were divided into four groups (eight animals in each group). (i) Control: rats not subjected to any treatment; (ii) DPE: DPE was orally administrated (1000 mg/kg body weight) for 21 days; (iii) RAD: rats' whole body exposed to 5 Gy of γ-rays; (iv) DPE + RAD: rats received DPE treatment for 21 days before γ-irradiation. Animals were sacrificed on the seventh day postexposure to radiation. RESULTS The results showed that pretreatment prior to irradiation with DPE resulted in a significantly higher 30-day survival rate of rats after exposure to different doses of γ-irradiation. Furthermore, DPE treatment resulted in a significant improvement in the hepatic redox state, manifested by a marked increase of superoxide dismutase (SOD) and catalase (CAT) activities and glutathione content associated with a significant decrease of malondialdehyde (MDA) level. In addition, DPE exhibited hepatoprotective effect evidenced by a marked increase in serum levels of insulin, testosterone, high-density lipoprotein-cholesterol (HDL-c) and hepatic glucose 6 phosphate dehydrogenase (G6PHD) activity associated with a significant decrease in serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), γ-glutamyl transferase (γ-GT), glucose, total cholesterol (TC), triglycerides (TG), low density-lipoprotein cholesterol (LDL-c) and hepatic glucose 6 phosphatase (G6Pase) activity, compared with irradiated group. Moreover, DPE showed positive modulation in the levels of hepatic metals [(iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn)]. CONCLUSIONS DPE treatment prior to gamma irradiation produced biochemical changes that could lead to a reduction in radiation-induced oxidative stress. Hence, we suggest that DPE may be useful as a new natural radioprotective agent.
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Affiliation(s)
- Nadia Abdel-Magied
- a Radiation Biology Department , National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority , Cairo , Egypt
| | - Amal G Ahmed
- a Radiation Biology Department , National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority , Cairo , Egypt
| | - Nahed Abo Zid
- a Radiation Biology Department , National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority , Cairo , Egypt
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Genome instability is a consequence of transcription deficiency in patients with bone marrow failure harboring biallelic ERCC6L2 variants. Proc Natl Acad Sci U S A 2018; 115:7777-7782. [PMID: 29987015 PMCID: PMC6064997 DOI: 10.1073/pnas.1803275115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bone marrow failure (BMF) is an inherited life-threatening condition characterized by defective hematopoiesis, developmental abnormalities, and predisposition to cancer. BMF caused by ERCC6L2 mutations is considered to be a genome instability syndrome, because DNA repair is compromised in patient cells. In this study, we report BMF cases with biallelic disease-causing variants and provide evidence from patients’ cells that transcription deficiency can explain the genome instability. Specifically, we demonstrate that ERCC6L2 participates in RNA polymerase II-mediated transcription via interaction with DNA-dependent protein kinase (DNA-PK) and resolves DNA–RNA hybrids (R loops). Collectively, our data point to a causal mechanism in BMF in which patients with ERCC6L2 mutations are defective in the repair of transcription-associated DNA damage. Biallelic variants in the ERCC excision repair 6 like 2 gene (ERCC6L2) are known to cause bone marrow failure (BMF) due to defects in DNA repair and mitochondrial function. Here, we report on eight cases of BMF from five families harboring biallelic variants in ERCC6L2, two of whom present with myelodysplasia. We confirm that ERCC6L2 patients’ lymphoblastoid cell lines (LCLs) are hypersensitive to DNA-damaging agents that specifically activate the transcription coupled nucleotide excision repair (TCNER) pathway. Interestingly, patients’ LCLs are also hypersensitive to transcription inhibitors that interfere with RNA polymerase II (RNA Pol II) and display an abnormal delay in transcription recovery. Using affinity-based mass spectrometry we found that ERCC6L2 interacts with DNA-dependent protein kinase (DNA-PK), a regulatory component of the RNA Pol II transcription complex. Chromatin immunoprecipitation PCR studies revealed ERCC6L2 occupancy on gene bodies along with RNA Pol II and DNA-PK. Patients’ LCLs fail to terminate transcript elongation accurately upon DNA damage and display a significant increase in nuclear DNA–RNA hybrids (R loops). Collectively, we conclude that ERCC6L2 is involved in regulating RNA Pol II-mediated transcription via its interaction with DNA-PK to resolve R loops and minimize transcription-associated genome instability. The inherited BMF syndrome caused by biallelic variants in ERCC6L2 can be considered as a primary transcription deficiency rather than a DNA repair defect.
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Cho J, Bing SJ, Kim A, Lee NH, Byeon SH, Kim GO, Jee Y. Beetroot (Beta vulgaris) rescues mice from γ-ray irradiation by accelerating hematopoiesis and curtailing immunosuppression. PHARMACEUTICAL BIOLOGY 2017; 55:306-319. [PMID: 27927068 PMCID: PMC6130760 DOI: 10.1080/13880209.2016.1237976] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 08/12/2016] [Accepted: 09/09/2016] [Indexed: 06/06/2023]
Abstract
CONTEXT Beetroot [Beta vulgaris Linné (Chenopodiaceae)], a vegetable usually consumed as a food or a medicinal plant in Europe, has been reported to have antioxidant and anti-inflammatory properties. Since the lymphohematopoietic system is the most sensitive tissue to ionizing radiation, protecting it from radiation damage is one of the best ways to decrease detrimental effects from radiation exposure. OBJECTIVE In this study, we evaluated the radio-protective effects of beetroot in hematopoietic stem cells (HSCs) and progenitor cells. MATERIALS AND METHODS Beetroot extract was administered at a dose of 400 mg/mouse per os (p.o.) three times into C57BL/6 mice and, at day 10 after γ-ray irradiation, diverse molecular presentations were measured and compared against non-irradiated and irradiated mice with PBS treatments. Survival of beetroot-fed and unfed irradiated animal was also compared. RESULTS Beetroot not only stimulated cell proliferation, but also minimized DNA damage of splenocytes. Beetroot also repopulated S-phase cells and increased Ki-67 or c-Kit positive cells in bone marrow. Moreover, beetroot-treated mice showed notable boosting of differentiation of HSCs into burst-forming units-erythroid along with increased production of IL-3. Also, beetroot-treated mice displayed enhancement in the level of hematocrit and hemoglobin as well as the number of red blood cell in peripheral blood. Beetroot diet improved survival rate of lethally exposed mice with a dose reduction factor (DRF) of 1.1. DISCUSSION AND CONCLUSION These results suggest that beetroot has the potency to preserve bone marrow integrity and stimulate the differentiation of HSCs against ionizing radiation.
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Affiliation(s)
- Jinhee Cho
- Department of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - So Jin Bing
- Department of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
| | - Areum Kim
- Department of Advanced Convergence Technology & Science, Jeju National University, Jeju, Republic of Korea
| | - Nam Ho Lee
- Department of Chemistry, Jeju National University, Jeju, Republic of Korea
| | - Sang-Hee Byeon
- Department of Chemistry, Jeju National University, Jeju, Republic of Korea
| | - Gi-Ok Kim
- Jeju Diversity Research Institute, Seogwipo, Republic of Korea
| | - Youngheun Jee
- Department of Veterinary Medicine and Veterinary Medical Research Institute, Jeju National University, Jeju, Republic of Korea
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DNA damage during the G0/G1 phase triggers RNA-templated, Cockayne syndrome B-dependent homologous recombination. Proc Natl Acad Sci U S A 2015; 112:E3495-504. [PMID: 26100862 DOI: 10.1073/pnas.1507105112] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Damage repair mechanisms at transcriptionally active sites during the G0/G1 phase are largely unknown. To elucidate these mechanisms, we introduced genome site-specific oxidative DNA damage and determined the role of transcription in repair factor assembly. We find that KU and NBS1 are recruited to damage sites independent of transcription. However, assembly of RPA1, RAD51C, RAD51, and RAD52 at such sites is strictly governed by active transcription and requires both wild-type Cockayne syndrome protein B (CSB) function and the presence of RNA in the G0/G1 phase. We show that the ATPase activity of CSB is indispensable for loading and binding of the recombination factors. CSB counters radiation-induced DNA damage in both cells and zebrafish models. Taken together, our results have uncovered a novel, RNA-based recombination mechanism by which CSB protects genome stability from strand breaks at transcriptionally active sites and may provide insight into the clinical manifestations of Cockayne syndrome.
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Kma L. Plant Extracts and Plant-Derived Compounds: Promising Players in Countermeasure Strategy Against Radiological Exposure: A Review. Asian Pac J Cancer Prev 2014; 15:2405-25. [DOI: 10.7314/apjcp.2014.15.6.2405] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Jaarsma D, van der Pluijm I, van der Horst GT, Hoeijmakers JH. Cockayne syndrome pathogenesis: Lessons from mouse models. Mech Ageing Dev 2013; 134:180-95. [DOI: 10.1016/j.mad.2013.04.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 03/04/2013] [Accepted: 04/08/2013] [Indexed: 10/27/2022]
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Vélez-Cruz R, Egly JM. Cockayne syndrome group B (CSB) protein: at the crossroads of transcriptional networks. Mech Ageing Dev 2013; 134:234-42. [PMID: 23562425 DOI: 10.1016/j.mad.2013.03.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 03/14/2013] [Accepted: 03/25/2013] [Indexed: 10/27/2022]
Abstract
Cockayne syndrome (CS) is a rare genetic disorder characterized by a variety of growth and developmental defects, photosensitivity, cachectic dwarfism, hearing loss, skeletal abnormalities, progressive neurological degeneration, and premature aging. CS arises due to mutations in the CSA and CSB genes. Both gene products are required for the transcription-coupled (TC) branch of the nucleotide excision repair (NER) pathway, however, the severe phenotype of CS patients is hard to reconcile with a sole defect in TC-NER. Studies using cells from patients and mouse models have shown that the CSB protein is involved in a variety of cellular pathways and plays a major role in the cellular response to stress. CSB has been shown to regulate processes such as the transcriptional recovery after DNA damage, the p53 transcriptional response, the response to hypoxia, the response to insulin-like growth factor-1 (IGF-1), transactivation of nuclear receptors, transcription of housekeeping genes and the transcription of rDNA. Some of these processes are also affected in combined XP/CS patients. These new advances in the function(s) of CSB shed light onto the etiology of the clinical features observed in CS patients and could potentially open therapeutic avenues for these patients in the future. Moreover, the study of CS could further our knowledge of the aging process.
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Affiliation(s)
- Renier Vélez-Cruz
- Department of Functional Genomics and Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM/Université de Strasbourg, BP 163, 67404 Illkirch Cedex, C. U. Strasbourg, France.
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McKenna DJ, Doherty BA, Downes CS, McKeown SR, McKelvey-Martin VJ. Use of the comet-FISH assay to compare DNA damage and repair in p53 and hTERT genes following ionizing radiation. PLoS One 2012; 7:e49364. [PMID: 23145163 PMCID: PMC3492288 DOI: 10.1371/journal.pone.0049364] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 10/09/2012] [Indexed: 12/02/2022] Open
Abstract
The alkaline single cell gel electrophoresis (comet) assay can be combined with fluorescent in situ hybridisation (FISH) methodology in order to investigate the localisation of specific gene domains within an individual cell. The number and position of the fluorescent signal(s) provides information about the relative damage and subsequent repair that is occurring in the targeted gene domain(s). In this study, we have optimised the comet-FISH assay to detect and compare DNA damage and repair in the p53 and hTERT gene regions of bladder cancer cell-lines RT4 and RT112, normal fibroblasts and Cockayne Syndrome (CS) fibroblasts following γ-radiation. Cells were exposed to 5Gy γ-radiation and repair followed for up to 60 minutes. At each repair time-point, the number and location of p53 and hTERT hybridisation spots was recorded in addition to standard comet measurements. In bladder cancer cell-lines and normal fibroblasts, the p53 gene region was found to be rapidly repaired relative to the hTERT gene region and the overall genome, a phenomenon that appeared to be independent of hTERT transcriptional activity. However, in the CS fibroblasts, which are defective in transcription coupled repair (TCR), this rapid repair of the p53 gene region was not observed when compared to both the hTERT gene region and the overall genome, proving the assay can detect variations in DNA repair in the same gene. In conclusion, we propose that the comet-FISH assay is a sensitive and rapid method for detecting differences in DNA damage and repair between different gene regions in individual cells in response to radiation. We suggest this increases its potential for measuring radiosensitivity in cells and may therefore have value in a clinical setting.
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Affiliation(s)
- Declan J McKenna
- Biomedical Sciences Research Institute, University of Ulster, Coleraine, Northern Ireland, United Kingdom.
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Friedl AA, Mazurek B, Seiler DM. Radiation-induced alterations in histone modification patterns and their potential impact on short-term radiation effects. Front Oncol 2012; 2:117. [PMID: 23050241 PMCID: PMC3445916 DOI: 10.3389/fonc.2012.00117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 08/28/2012] [Indexed: 12/12/2022] Open
Abstract
Detection and repair of radiation-induced DNA damage occur in the context of chromatin. An intricate network of mechanisms defines chromatin structure, including DNA methylation, incorporation of histone variants, histone modifications, and chromatin remodeling. In the last years it became clear that the cellular response to radiation-induced DNA damage involves all of these mechanisms. Here we focus on the current knowledge on radiation-induced alterations in post-translational histone modification patterns and their effect on the chromatin accessibility, transcriptional regulation and chromosomal stability.
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Affiliation(s)
- Anna A Friedl
- Department of Radiation Oncology, Ludwig-Maximilians-University Munich, Germany
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Berquist BR, Wilson DM. Pathways for repairing and tolerating the spectrum of oxidative DNA lesions. Cancer Lett 2012; 327:61-72. [PMID: 22353689 DOI: 10.1016/j.canlet.2012.02.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/26/2012] [Accepted: 02/01/2012] [Indexed: 01/03/2023]
Abstract
Reactive oxygen species (ROS) arise from both endogenous and exogenous sources. These reactive molecules possess the ability to damage both the DNA nucleobases and the sugar phosphate backbone, leading to a wide spectrum of lesions, including non-bulky (8-oxoguanine and formamidopyrimidine) and bulky (cyclopurine and etheno adducts) base modifications, abasic sites, non-conventional single-strand breaks, protein-DNA adducts, and intra/interstrand DNA crosslinks. Unrepaired oxidative DNA damage can result in bypass mutagenesis during genome copying or gene expression, or blockage of the essential cellular processes of DNA replication or transcription. Such outcomes underlie numerous pathologies, including, but not limited to, carcinogenesis and neurodegeneration, as well as the aging process. Cells have adapted and evolved defense systems against the deleterious effects of ROS, and specifically devote a number of cellular DNA repair and tolerance pathways to combat oxidative DNA damage. Defects in these protective pathways trigger hereditary human diseases that exhibit increased cancer incidence, developmental defects, neurological abnormalities, and/or premature aging. We review herein classic and atypical oxidative DNA lesions, outcomes of encountering these damages during DNA replication and transcription, and the consequences of losing the ability to repair the different forms of oxidative DNA damage. We particularly focus on the hereditary human diseases Xeroderma Pigmentosum, Cockayne Syndrome and Fanconi Anemia, which may involve defects in the efficient repair of oxidative modifications to chromosomal DNA.
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Affiliation(s)
- Brian R Berquist
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, 77843, United States
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Cramers P, Filon AR, Pines A, Kleinjans JC, Mullenders LHF, van Zeeland AA. Enhanced nucleotide excision repair in human fibroblasts pre-exposed to ionizing radiation. Photochem Photobiol 2011; 88:147-53. [PMID: 22017241 DOI: 10.1111/j.1751-1097.2011.01019.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cellular protection against deleterious effects of DNA damaging agents requires an intricate network of defense mechanisms known as the DNA damage response (DDR). Ionizing radiation (IR) mediated activation of the DDR induces a transcriptional upregulation of genes that are also involved in nucleotide excision repair (NER). This suggests that pre-exposure to X-rays might stimulate NER in human cells. Here, we demonstrate in normal human fibroblasts that UV-induced NER is augmented by pre-exposure to IR and that this increased repair is accompanied by elevated mRNA and protein levels of the NER factors XPC and DDB2. Furthermore, when IR exposure precedes local UV irradiation, the presence of XPC and DDB2 at the sites of local UV damages is increased. This increase might be p53 dependent, but the mechanism of X-ray specific stabilization of p53 is unclear as both X-rays and UV stabilize p53.
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Affiliation(s)
- Patricia Cramers
- Department of Toxicogenetics, Leiden University Medical Center, Leiden, The Netherlands
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