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Peters NE, Ferguson BJ, Mazzon M, Fahy AS, Krysztofinska E, Arribas-Bosacoma R, Pearl LH, Ren H, Smith GL. A mechanism for the inhibition of DNA-PK-mediated DNA sensing by a virus. PLoS Pathog 2013; 9:e1003649. [PMID: 24098118 PMCID: PMC3789764 DOI: 10.1371/journal.ppat.1003649] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 08/06/2013] [Indexed: 12/17/2022] Open
Abstract
The innate immune system is critical in the response to infection by pathogens and it is activated by pattern recognition receptors (PRRs) binding to pathogen associated molecular patterns (PAMPs). During viral infection, the direct recognition of the viral nucleic acids, such as the genomes of DNA viruses, is very important for activation of innate immunity. Recently, DNA-dependent protein kinase (DNA-PK), a heterotrimeric complex consisting of the Ku70/Ku80 heterodimer and the catalytic subunit DNA-PKcs was identified as a cytoplasmic PRR for DNA that is important for the innate immune response to intracellular DNA and DNA virus infection. Here we show that vaccinia virus (VACV) has evolved to inhibit this function of DNA-PK by expression of a highly conserved protein called C16, which was known to contribute to virulence but by an unknown mechanism. Data presented show that C16 binds directly to the Ku heterodimer and thereby inhibits the innate immune response to DNA in fibroblasts, characterised by the decreased production of cytokines and chemokines. Mechanistically, C16 acts by blocking DNA-PK binding to DNA, which correlates with reduced DNA-PK-dependent DNA sensing. The C-terminal region of C16 is sufficient for binding Ku and this activity is conserved in the variola virus (VARV) orthologue of C16. In contrast, deletion of 5 amino acids in this domain is enough to knockout this function from the attenuated vaccine strain modified vaccinia virus Ankara (MVA). In vivo a VACV mutant lacking C16 induced higher levels of cytokines and chemokines early after infection compared to control viruses, confirming the role of this virulence factor in attenuating the innate immune response. Overall this study describes the inhibition of DNA-PK-dependent DNA sensing by a poxvirus protein, adding to the evidence that DNA-PK is a critical component of innate immunity to DNA viruses.
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Affiliation(s)
- Nicholas E. Peters
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Brian J. Ferguson
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
| | - Michela Mazzon
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
| | - Aodhnait S. Fahy
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Ewelina Krysztofinska
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
| | - Raquel Arribas-Bosacoma
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, United Kingdom
| | - Laurence H. Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, United Kingdom
| | - Hongwei Ren
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
| | - Geoffrey L. Smith
- Section of Virology, Department of Medicine, Imperial College London, Norfolk Place, London, United Kingdom
- Department of Pathology, Cambridge University, Cambridge, United Kingdom
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Chen HY, Lu HF, Yang JS, Kuo SC, Lo C, Yang MD, Chiu TH, Chueh FS, Ho HC, Ko YC, Chung JG. The novel quinolone CHM-1 induces DNA damage and inhibits DNA repair gene expressions in a human osterogenic sarcoma cell line. Anticancer Res 2010; 30:4187-4192. [PMID: 21036739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
20-Fluoro-6,7-methylenedioxy-2-phenyl-4-quino-lone (CHM-1) has been reported to induce cell cycle arrest and apoptosis in many types of cancer cells. However, there is no available information to show CHM-1 affecting DNA damage and expression of associated repair genes. Herein, we investigated whether or not CHM-1 induced DNA damage and affected DNA repair gene expression in U-2 OS human osterogenic sarcoma cells. The comet assay showed that incubation of U-2 OS cells with 0, 0.75, 1.5, 3 and 6 μM of CHM-1 led to a longer DNA migration smear (comet tail). DNA gel electrophoresis showed that 3 μM of CHM-1 for 24 and 48 h treatment induced DNA fragmentation in U-2 OS cells. Real-time PCR analysis showed that treatment with 3 μM of CHM-1 for 24 h reduced the mRNA expression levels of ataxia telangiectasia mutated (ATM), ataxia-telangiectasia and Rad3-related (ATR), breast cancer 1, early onset (BRCA1), 14-3-3sigma (14-3-3σ), DNA-dependent serine/threonine protein kinase (DNA-PK) and O(6)-methylguanine-DNA methyltransferase (MGMT) genes in a time-dependent manner. Taken together, the results indicate that CHM-1 caused DNA damage and reduced DNA repair genes in U-2 OS cells, which may be the mechanism for CHM-1-inhibited cell growth and induction of apoptosis.
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Affiliation(s)
- Hung-Yi Chen
- Schools of Pharmacy, China Medical University, Taichung, Taiwan, ROC
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Chen YY, Chiang SY, Lin JG, Yang JS, Ma YS, Liao CL, Lai TY, Tang NY, Chung JG. Emodin, aloe-emodin and rhein induced DNA damage and inhibited DNA repair gene expression in SCC-4 human tongue cancer cells. Anticancer Res 2010; 30:945-951. [PMID: 20393018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In our primary studies, we have shown that emodin, aloe-emodin and rhein induced cytotoxic effects, including cell cycle arrest and apoptosis in SCC-4 human tongue cancer cells. However, details regarding their effects on DNA damage and repair gene expression in SCC-4 cells are not clear. We investigated whether or not emodin, aloe-emodin and rhein induced DNA damage and inhibited DNA repair gene expression in SCC-4 cells. Comet assay (single cell electrophoresis) indicated that incubation of SCC-4 cells with 0, 20, 30 and 40 microM of emodin, 0, 25, 50 and 100 microM of aloe-emodin or rhein led to a longer DNA migration smear (comet tail). This means that all examined agents induced DNA damage in SCC-4 cells and these effects are dose-dependent but emodin is stronger than that of aloe-emodin or rhein. The results from real-time PCR assay demonstrated that 30 microM of emodin or aloe-emodin used for 24 and 48 h treatment in SCC-4 cells significantly inhibited expression of genes associated with DNA damage and repair [ataxia telangiectasia mutated (ATM); ataxia-telangiectasia and Rad3-related (ATR); 14-3-3sigma (14-3-3sigma); breast cancer 1, early onset (BRCA1); and DNA-dependent serine/threonine protein kinase (DNA-PK)]; only rhein suppressed the expression of O(6)-methylguanine-DNA methyltransferase (MGMT) mRNA with 48 h treatment, but had no effect on ATM expression. On 24 h treatment, only aloe-emodin significantly affected ATM expression. These effects may be the vital factors for emodin, aloe-emodin and rhein induction of DNA damage in vitro. In conclusion, these agents induced DNA damage followed by the inhibition of DNA repair-associated gene expressions, including ATM, ATR, 14-3-3sigma, BRCA1, DNA-PK and MGMT in SCC-4 human tongue cancer cells.
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Affiliation(s)
- Ya-Yin Chen
- China Medical University, No 91, Hsueh-Shih Road, Taichung 404, Taiwan
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Abstract
To study the relationships between different DNA repair pathways, we established a set of clones in which one specific DNA repair gene was silenced using long-term RNA interference in HeLa cell line. We focus here on genes involved in either nucleotide excision repair (XPA and XPC) or nonhomologous end joining (NHEJ; DNA-PKcs and XRCC4). As expected, XPA(KD) (knock down) and XPC(KD) cells were highly sensitive to UVC. DNA-PKcs(KD) and XRCC4(KD) cells presented an increased sensitivity to various inducers of double-strand breaks (DSBs) and a 70% to 80% reduction of in vitro NHEJ activity. Long-term silencing of XPC gene expression led to an increased sensitivity to etoposide, a topoisomerase II inhibitor that creates DSBs through the progression of DNA replication forks. XPC(KD) cells also showed intolerance toward acute gamma-ray irradiation. We showed that XPC(KD) cells exhibited an altered spectrum of NHEJ products with decreased levels of intramolecular joined products. Moreover, in both XPC(KD) and DNA-PKcs(KD) cells, XRCC4 and ligase IV proteins were mobilized on damaged nuclear structures at lower doses of DSB inducer. In XPC-proficient cells, XPC protein was released from nuclear structures after induction of DSBs. By contrast, silencing of XPA gene expression did not have any effect on sensitivity to DSB or NHEJ. Our results suggest that XPC deficiency, certainly in combination with other genetic defects, may contribute to impair DSB repair.
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Affiliation(s)
- Emmanuelle Despras
- Commissariat à l'Energie Atomique, Laboratoire de Génétique de la Radiosensibilité, Département de Radiobiologie et de Radiopathologie, Direction des Sciences du Vivant, Fontenay-aux-Roses, France.
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Luo J, Peng ZG, Chen Y, Lai YR, Lu YY, Song SJ. [Gene of DNA-dependent protein kinase catalylic subunit in chronic myeloid leukemia]. Zhongguo Shi Yan Xue Ye Xue Za Zhi 2007; 15:248-52. [PMID: 17493325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This study was aimed to investigate the expression and regulation mechanism of DNA-dependent protein kinase catalylic subunit (DNA-PKcs) in chronic myeloid leukemia (CML) and its role in blast crisis of CML. Expression of DNA-PKcs mRNA was detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and DNA-PKcs protein by Western blot in 62 CML patients and K562, as compared to those of 23 normal individual controls. In 26 CML patients received allogeneic peripheral blood stem cell transplantation (allo-PBSCT) and 4 CML patients treated with imatinib, the expression of bcr-abl mRNA and DNA-PKcs protein was detected by RT-PCR and Western blot, respectively. After treatment with imatinib in mononuclear cell (MNC) of CML patients and K562 in vitro, expression of DNA-PKcs mRNA was detected by RT-PCR and DNA-PKcs protein level, tyrosine phosphorylation of bcr-abl fusion protein were detected by Western blot. The results showed that the expression of DNA-PKcs protein was significantly lower in CML and K562 than those in normal control (P<0.05). In 26 CML patients received allo-PBSCT and 4 CML patients treated with imatinib, the expression of DNA-PKcs protein was enhanced while the expression of bcr-abl mRNA decreased. After treatment of MNC of CML and K562 with imatinib in vitro, the expression of DNA-PKcs protein was enhanced while tyrosine phosphorylation of bcr-abl fusion protein decreased. It is concluded that the expression of DNA-PKcs protein is down-regulate by bcr-abl fusion gene, and the bcr-abl fusion gene down-regulate the expression of DNA-PKcs protein by post-transcriptional mechanism; the decrease of DNA-PKcs protein expression may be one of mechanisms underlying the acute transformation of CML.
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MESH Headings
- Adult
- Aged
- Benzamides
- Bone Marrow Cells/metabolism
- DNA-Activated Protein Kinase/biosynthesis
- DNA-Activated Protein Kinase/genetics
- Female
- Fusion Proteins, bcr-abl/biosynthesis
- Fusion Proteins, bcr-abl/genetics
- Humans
- Imatinib Mesylate
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/therapy
- Male
- Middle Aged
- Peripheral Blood Stem Cell Transplantation
- Piperazines/therapeutic use
- Pyrimidines/therapeutic use
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
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Affiliation(s)
- Jun Luo
- Department of Hematology, The First Affiliated Hospital of Guangxi Medical University, Nanning 530021, China
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Mitra AK, Bhat N, Sarma A, Krishna M. Alteration in the expression of signaling parameters following carbon ion irradiation. Mol Cell Biochem 2006; 276:169-73. [PMID: 16132698 DOI: 10.1007/s11010-005-3903-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Accepted: 03/16/2005] [Indexed: 11/28/2022]
Abstract
Ionizing radiation induces DNA damage, which generates a complex array of genotoxic responses. These responses depend on the type of DNA damage, which in turn can lead to unique cellular responses. High LET radiation results in clustered damages. This evokes specific signaling responses, which can be cytotoxic or cytoprotective in nature. In the present study the effect of carbon ion irradiation on p 44/42 MAPK and NF-kappaB, which are essentially survival factors, have been studied. Moreover, the effect of inhibition of DNA-PK, which is an important component of DNA repair mechanism, with wortmanin on these signaling factors has been studied. The expression of p 44/42 MAPK was different at 0.1 Gy and 1 Gy and wortmanin was found to inhibit its expression. NF-kappaB expression was higher at 1 Gy than at 0.1 Gy and its expression is unaffected by inhibition of DNA-PK. The notable findings of this study are that the responses to high and low dose of high LET radiation are essentially different and the 6 h time point post irradiation is crucial in deciding the response and needs further investigation.
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Affiliation(s)
- Anirban Kumar Mitra
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
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Yu ZJ, Sui JG, Ding YQ, Cao ZS, Zhou PK, Wu DC. [Expression of DNA-PK in hepato- and cholangio-neoplasms and its significance]. Zhonghua Gan Zang Bing Za Zhi 2004; 12:652-5. [PMID: 15623371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
OBJECTIVE To characterize DNA-PKcs and Ku70 expressions in hepato- and cholangio-neoplastic tissues and the association with the degree of malignancy and invasiveness of the tumors. METHODS The expression of DNA-PKcs and Ku70 was examined in 47 cases of hepato- or cholangio-neoplasm by immunohistochemistry. RESULTS Ku70 was expressed in all of the neoplastic tissues examined and with a little variation in levels. The highest expression was observed in adenocarcinomas and adenomas. There was no statistically significant association between Ku70 expression level and the degree of their malignancy extent or invasiveness. In contrast to Ku 70, a wide variation in expression levels of DNA-Pkcs was observed among different types of neoplastic tissues. The highest ratio of positive expressing cells was detected in hepatocellular carcinomas (92.1%), which was significantly higher than that in cholangioadeno carcinomas (65.3%) and biliary cystadenocarcinomas (51.9%). Low or no expression level was detected in papillary adenoma cases. DNA-PKcs expression of invasive adenomas and adeno-carcinomas (61.2%) was significantly higher than that of non-invasive adenomas and adeno-carcinomas (30.4%). There was no expression observed in the normal tissues adjacent to the tumors. CONCLUSION DNA-PKcs is expressed in hepato- and cholangio-neoplasms and its variable level of expression is associated with the types of the tumor and their degree of malignancy and invasiveness. DNA-PKcs could be recognized as a new biomarker for liver neoplasm.
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Affiliation(s)
- Zi-jian Yu
- Beijing Institute of Radiation Medicine, Beijing 100850, China
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