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Orsburn BC. Analyzing Posttranslational Modifications in Single Cells. Methods Mol Biol 2024; 2817:145-156. [PMID: 38907153 DOI: 10.1007/978-1-0716-3934-4_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2024]
Abstract
With the rapid expansion of capabilities in the analysis of proteins in single cells, we can now identify multiple classes of protein posttranslational modifications on some of these proteins. Each new technology that has increased the number of proteins measured per cell has likewise increased our ability to identify and quantify modified peptides. In this chapter, I will discuss our current capabilities, concerns, and challenges specific to this emerging field of study and the inevitable demand for services, providing a general review of concepts that should be considered.
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Affiliation(s)
- Benjamin C Orsburn
- The Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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2
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Dingler FA, Wang M, Mu A, Millington CL, Oberbeck N, Watcham S, Pontel LB, Kamimae-Lanning AN, Langevin F, Nadler C, Cordell RL, Monks PS, Yu R, Wilson NK, Hira A, Yoshida K, Mori M, Okamoto Y, Okuno Y, Muramatsu H, Shiraishi Y, Kobayashi M, Moriguchi T, Osumi T, Kato M, Miyano S, Ito E, Kojima S, Yabe H, Yabe M, Matsuo K, Ogawa S, Göttgens B, Hodskinson MRG, Takata M, Patel KJ. Two Aldehyde Clearance Systems Are Essential to Prevent Lethal Formaldehyde Accumulation in Mice and Humans. Mol Cell 2020; 80:996-1012.e9. [PMID: 33147438 PMCID: PMC7758861 DOI: 10.1016/j.molcel.2020.10.012] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/20/2020] [Accepted: 10/08/2020] [Indexed: 01/04/2023]
Abstract
Reactive aldehydes arise as by-products of metabolism and are normally cleared by multiple families of enzymes. We find that mice lacking two aldehyde detoxifying enzymes, mitochondrial ALDH2 and cytoplasmic ADH5, have greatly shortened lifespans and develop leukemia. Hematopoiesis is disrupted profoundly, with a reduction of hematopoietic stem cells and common lymphoid progenitors causing a severely depleted acquired immune system. We show that formaldehyde is a common substrate of ALDH2 and ADH5 and establish methods to quantify elevated blood formaldehyde and formaldehyde-DNA adducts in tissues. Bone-marrow-derived progenitors actively engage DNA repair but also imprint a formaldehyde-driven mutation signature similar to aging-associated human cancer mutation signatures. Furthermore, we identify analogous genetic defects in children causing a previously uncharacterized inherited bone marrow failure and pre-leukemic syndrome. Endogenous formaldehyde clearance alone is therefore critical for hematopoiesis and in limiting mutagenesis in somatic tissues.
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Affiliation(s)
- Felix A Dingler
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Meng Wang
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Department of Haematology, University of Cambridge, Cambridge, UK
| | - Anfeng Mu
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan; Department of Genome Biology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan; Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | | | - Nina Oberbeck
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sam Watcham
- Department of Haematology, University of Cambridge, Cambridge, UK; Wellcome-MRC Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, UK
| | - Lucas B Pontel
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET, Polo Científico Tecnológico, Godoy Cruz 2390, C1425FQD Buenos Aires, Argentina
| | | | - Frederic Langevin
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Camille Nadler
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Rebecca L Cordell
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK
| | - Paul S Monks
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK
| | - Rui Yu
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nicola K Wilson
- Department of Haematology, University of Cambridge, Cambridge, UK; Wellcome-MRC Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, UK
| | - Asuka Hira
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan; Department of Genome Biology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Kenichi Yoshida
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Minako Mori
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan; Department of Genome Biology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan; Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yusuke Okamoto
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan; Department of Genome Biology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan; Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yusuke Okuno
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hideki Muramatsu
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yuichi Shiraishi
- Section of Genome Analysis Platform, Center for Cancer Genomic and Advanced Therapeutics, National Cancer Center, Tokyo, Japan
| | - Masayuki Kobayashi
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Hematology, Kyoto Katsura Hospital, Kyoto, Japan
| | | | - Tomoo Osumi
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan
| | - Motohiro Kato
- Children's Cancer Center, National Center for Child Health and Development, Tokyo, Japan
| | - Satoru Miyano
- Laboratory of DNA Information Analysis, Human Genome Center, The Institute of Medical Science, University of Tokyo, Tokyo Japan
| | - Etsuro Ito
- Department of Pediatrics, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Seiji Kojima
- Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiromasa Yabe
- Department of Innovative Medical Science, Tokai University School of Medicine, Isehara, Japan
| | - Miharu Yabe
- Department of Innovative Medical Science, Tokai University School of Medicine, Isehara, Japan
| | - Keitaro Matsuo
- Division of Cancer Epidemiology and Prevention, Aichi Cancer Center Research Institute, Nagoya, Japan; Division of Analytical Cancer Epidemiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Seishi Ogawa
- Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Medicine, Center for Hematology and Regenerative Medicine, Karolinska Institute, Sweden; Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto, Japan
| | - Berthold Göttgens
- Department of Haematology, University of Cambridge, Cambridge, UK; Wellcome-MRC Cambridge Stem Cell Institute, Jeffrey Cheah Biomedical Centre, University of Cambridge, Cambridge, UK
| | | | - Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan; Department of Genome Biology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
| | - Ketan J Patel
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK; MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK.
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3
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Choi JE, Chung WH. Synthetic lethal interaction between oxidative stress response and DNA damage repair in the budding yeast and its application to targeted anticancer therapy. J Microbiol 2018; 57:9-17. [DOI: 10.1007/s12275-019-8475-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/12/2018] [Accepted: 10/12/2018] [Indexed: 12/11/2022]
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4
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Ghosh R, Roy S, Franco S. PARP1 depletion induces RIG-I-dependent signaling in human cancer cells. PLoS One 2018; 13:e0194611. [PMID: 29590171 PMCID: PMC5874037 DOI: 10.1371/journal.pone.0194611] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/06/2018] [Indexed: 12/11/2022] Open
Abstract
DNA Damage Response (DDR) and DNA repair pathways are emerging as potent, ubiquitous suppressors of innate immune signaling in human cells. Here, we show that human cells surviving depletion of the Single Strand Break (SSB) repair protein PARP1 undergo p21-dependent senescence or cell cycle checkpoint activation in the context of activation of innate immune signaling, or viral mimicry. Specifically, we observe induction of a large number of interferon-stimulated genes (ISGs) and multiple pattern recognition receptors (PRRs; including RIG-I, MDA-5, MAVS, TLR3 and STING) and increased nuclear IRF3 staining. Mechanistically, depletion of the double-stranded RNA (dsRNA) helicase RIG-I or its downstream effector MAVS specifically rescues ISG induction in PARP1-depleted cells, suggesting that the RIG-I/MAVS pathway is required for sustained ISG expression in this context. Experiments with conditioned media or a neutralizing antibody to the α/β-IFN receptor revealed that persistent ISG expression additionally requires an autocrine/paracrine loop. Finally, loss of PARP1 and radiation-induced DNA damage strongly synergize in the induction of p21 and ISGs. Overall, these findings increase our understanding of how PARP1 may suppress deleterious phenotypes associated to aging, inflammation and cancer in humans.
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Affiliation(s)
- Rajib Ghosh
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Sanchita Roy
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Sonia Franco
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- * E-mail:
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5
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Garaycoechea JI, Crossan GP, Langevin F, Mulderrig L, Louzada S, Yang F, Guilbaud G, Park N, Roerink S, Nik-Zainal S, Stratton MR, Patel KJ. Alcohol and endogenous aldehydes damage chromosomes and mutate stem cells. Nature 2018; 553:171-177. [PMID: 29323295 PMCID: PMC6047743 DOI: 10.1038/nature25154] [Citation(s) in RCA: 246] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 11/21/2017] [Indexed: 12/13/2022]
Abstract
Haematopoietic stem cells renew blood. Accumulation of DNA damage in these cells promotes their decline, while misrepair of this damage initiates malignancies. Here we describe the features and mutational landscape of DNA damage caused by acetaldehyde, an endogenous and alcohol-derived metabolite. This damage results in DNA double-stranded breaks that, despite stimulating recombination repair, also cause chromosome rearrangements. We combined transplantation of single haematopoietic stem cells with whole-genome sequencing to show that this damage occurs in stem cells, leading to deletions and rearrangements that are indicative of microhomology-mediated end-joining repair. Moreover, deletion of p53 completely rescues the survival of aldehyde-stressed and mutated haematopoietic stem cells, but does not change the pattern or the intensity of genome instability within individual stem cells. These findings characterize the mutation of the stem-cell genome by an alcohol-derived and endogenous source of DNA damage. Furthermore, we identify how the choice of DNA-repair pathway and a stringent p53 response limit the transmission of aldehyde-induced mutations in stem cells.
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Affiliation(s)
- Juan I Garaycoechea
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Gerry P Crossan
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Frédéric Langevin
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Lee Mulderrig
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sandra Louzada
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Fentang Yang
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Guillaume Guilbaud
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Naomi Park
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Sophie Roerink
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | | | | | - Ketan J Patel
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Rd, Cambridge CB2 0QQ, UK
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6
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Schuhwerk H, Bruhn C, Siniuk K, Min W, Erener S, Grigaravicius P, Krüger A, Ferrari E, Zubel T, Lazaro D, Monajembashi S, Kiesow K, Kroll T, Bürkle A, Mangerich A, Hottiger M, Wang ZQ. Kinetics of poly(ADP-ribosyl)ation, but not PARP1 itself, determines the cell fate in response to DNA damage in vitro and in vivo. Nucleic Acids Res 2017; 45:11174-11192. [PMID: 28977496 PMCID: PMC5737718 DOI: 10.1093/nar/gkx717] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 08/08/2017] [Indexed: 12/21/2022] Open
Abstract
One of the fastest cellular responses to genotoxic stress is the formation of poly(ADP-ribose) polymers (PAR) by poly(ADP-ribose)polymerase 1 (PARP1, or ARTD1). PARP1 and its enzymatic product PAR regulate diverse biological processes, such as DNA repair, chromatin remodeling, transcription and cell death. However, the inter-dependent function of the PARP1 protein and its enzymatic activity clouds the mechanism underlying the biological response. We generated a PARP1 knock-in mouse model carrying a point mutation in the catalytic domain of PARP1 (D993A), which impairs the kinetics of the PARP1 activity and the PAR chain complexity in vitro and in vivo, designated as hypo-PARylation. PARP1D993A/D993A mice and cells are viable and show no obvious abnormalities. Despite a mild defect in base excision repair (BER), this hypo-PARylation compromises the DNA damage response during DNA replication, leading to cell death or senescence. Strikingly, PARP1D993A/D993A mice are hypersensitive to alkylation in vivo, phenocopying the phenotype of PARP1 knockout mice. Our study thus unravels a novel regulatory mechanism, which could not be revealed by classical loss-of-function studies, on how PAR homeostasis, but not the PARP1 protein, protects cells and organisms from acute DNA damage.
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Affiliation(s)
- Harald Schuhwerk
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Christopher Bruhn
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Kanstantsin Siniuk
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Wookee Min
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Suheda Erener
- Department of Molecular Mechanisms of Disease, University of Zurich, CH-8057 Zurich, Switzerland
| | - Paulius Grigaravicius
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Annika Krüger
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRSCB), University of Konstanz, 78457 Konstanz, Germany
| | - Elena Ferrari
- Department of Molecular Mechanisms of Disease, University of Zurich, CH-8057 Zurich, Switzerland
| | - Tabea Zubel
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRSCB), University of Konstanz, 78457 Konstanz, Germany
| | - David Lazaro
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Shamci Monajembashi
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Kirstin Kiesow
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Torsten Kroll
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany
| | - Alexander Bürkle
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Aswin Mangerich
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Michael Hottiger
- Department of Molecular Mechanisms of Disease, University of Zurich, CH-8057 Zurich, Switzerland
| | - Zhao-Qi Wang
- Leibniz Institute on Aging - Fritz-Lipmann Institute (FLI), Beutenbergstr. 11, 07745 Jena, Germany.,Faculty of Biology and Pharmacy, Friedrich Schiller University Jena, Germany
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The inhibitory effect of minocycline on radiation-induced neuronal apoptosis via AMPKα1 signaling-mediated autophagy. Sci Rep 2017; 7:16373. [PMID: 29180765 PMCID: PMC5703722 DOI: 10.1038/s41598-017-16693-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 10/11/2017] [Indexed: 12/14/2022] Open
Abstract
Due to an increasing concern about radiation-induced cognitive deficits for brain tumor patients receiving radiation therapy, developing and evaluating countermeasures has become inevitable. Our previous study has found that minocycline, a clinical available antibiotics that can easily cross the blood brain barrier, mitigates radiation-induced long-term memory loss in rats, accompanied by decreased hippocampal neuron apoptosis. Thus, in the present study, we report an unknown mechanism underlying the neuroprotective effect of minocycline. We demonstrated that minocycline prevented primary neurons from radiation-induced apoptosis and promoted radiation-induced autophagy in vitro. Moreover, using an immortalized mouse hippocampal neuronal cell line, HT22 cells, we found that the protective effect of minocycline on irradiated HT22 cells was not related to DNA damage repair since minocycline did not facilitate DNA DSB repair in irradiated HT22 cells. Further investigation showed that minocycline significantly enhanced X-irradiation-induced AMPKα1 activation and autophagy, thus resulting in decreased apoptosis. Additionally, although the antioxidant potential of minocycline might contribute to its apoptosis-inhibitory effect, it was not involved in its enhancive effect on radiation-induced AMPKα1-mediated autophagy. Taken together, we have revealed a novel mechanism for the protective effect of minocycline on irradiated neurons, e.g. minocycline protects neurons from radiation-induced apoptosis via enhancing radiation-induced AMPKα1-mediated autophagy.
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Liu C, Vyas A, Kassab MA, Singh AK, Yu X. The role of poly ADP-ribosylation in the first wave of DNA damage response. Nucleic Acids Res 2017; 45:8129-8141. [PMID: 28854736 PMCID: PMC5737498 DOI: 10.1093/nar/gkx565] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 06/15/2017] [Accepted: 06/20/2017] [Indexed: 01/11/2023] Open
Abstract
Poly ADP-ribose polymerases (PARPs) catalyze massive protein poly ADP-ribosylation (PARylation) within seconds after the induction of DNA single- or double-strand breaks. PARylation occurs at or near the sites of DNA damage and promotes the recruitment of DNA repair factors via their poly ADP-ribose (PAR) binding domains. Several novel PAR-binding domains have been recently identified. Here, we summarize these and other recent findings suggesting that PARylation may be the critical event that mediates the first wave of the DNA damage response. We also discuss the potential for functional crosstalk with other DNA damage-induced post-translational modifications.
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Affiliation(s)
- Chao Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Aditi Vyas
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Muzaffer A. Kassab
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Anup K. Singh
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | - Xiaochun Yu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
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Yang ZM, Liao XM, Chen Y, Shen YY, Yang XY, Su Y, Sun YM, Gao YL, Ding J, Zhang A, He JX, Miao ZH. Combining 53BP1 with BRCA1 as a biomarker to predict the sensitivity of poly(ADP-ribose) polymerase (PARP) inhibitors. Acta Pharmacol Sin 2017; 38:1038-1047. [PMID: 28414200 DOI: 10.1038/aps.2017.8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 02/06/2017] [Indexed: 12/24/2022] Open
Abstract
Over half of patients with BRCA1-deficient cancers do not respond to treatment with poly(ADP-ribose) polymerase (PARP) inhibitors. In this study, we report that a combination of 53BP1 and BRCA1 may serve as a biomarker of PARP inhibitor sensitivity. Based on the mRNA levels of four homologous recombination repair (HR) genes and PARP inhibitor sensitivity, we selected BRCA1-deficient MDA-MB-436 cells to conduct RNA interference. Reducing expression of 53BP1, but not the other three HR genes, was found to lower simmiparib sensitivity. Additionally, we generated 53BP1-/-/BRCA1-/- clonal variants by the transcription activator-like effector nuclease (TALEN) technique and found that depleting 53BP1 impaired PARP inhibitor sensitivity with a 36.7-fold increase in their IC50 values. Consistent with its effect on PARP inhibitor sensitivity, 53BP1 loss alleviated cell cycle arrest and apoptosis and partially restored HR function. Importantly, 53BP1 depletion dramatically reduced the ability of PARP inhibitors to suppress tumor growth in vivo. The inhibition rate of simmiparib was 74.16% for BRCA1-deficient MDA-MB-436 xenografts, but only 7.79% for 53BP1/BRCA1-deficient xenografts. Re-expressing 53BP1 in the dual-deficient cells restored PARP inhibitor sensitivity and the levels of HR regulators. Considering that at least 10% of BRCA1-deficient breast and ovarian cancers have reduced expression of 53BP1, using a combination of 53BP1 with BRCA1 as a biomarker for patient selection should reduce the number of patients undergoing futile treatment with PARP inhibitors.
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10
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Combining 53BP1 with BRCA1 as a biomarker to predict the sensitivity of poly(ADP-ribose) polymerase (PARP) inhibitors. Acta Pharmacol Sin 2017. [PMID: 28414200 DOI: 10.1038/aps.2017.8] [] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Over half of patients with BRCA1-deficient cancers do not respond to treatment with poly(ADP-ribose) polymerase (PARP) inhibitors. In this study, we report that a combination of 53BP1 and BRCA1 may serve as a biomarker of PARP inhibitor sensitivity. Based on the mRNA levels of four homologous recombination repair (HR) genes and PARP inhibitor sensitivity, we selected BRCA1-deficient MDA-MB-436 cells to conduct RNA interference. Reducing expression of 53BP1, but not the other three HR genes, was found to lower simmiparib sensitivity. Additionally, we generated 53BP1-/-/BRCA1-/- clonal variants by the transcription activator-like effector nuclease (TALEN) technique and found that depleting 53BP1 impaired PARP inhibitor sensitivity with a 36.7-fold increase in their IC50 values. Consistent with its effect on PARP inhibitor sensitivity, 53BP1 loss alleviated cell cycle arrest and apoptosis and partially restored HR function. Importantly, 53BP1 depletion dramatically reduced the ability of PARP inhibitors to suppress tumor growth in vivo. The inhibition rate of simmiparib was 74.16% for BRCA1-deficient MDA-MB-436 xenografts, but only 7.79% for 53BP1/BRCA1-deficient xenografts. Re-expressing 53BP1 in the dual-deficient cells restored PARP inhibitor sensitivity and the levels of HR regulators. Considering that at least 10% of BRCA1-deficient breast and ovarian cancers have reduced expression of 53BP1, using a combination of 53BP1 with BRCA1 as a biomarker for patient selection should reduce the number of patients undergoing futile treatment with PARP inhibitors.
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11
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Combining 53BP1 with BRCA1 as a biomarker to predict the sensitivity of poly(ADP-ribose) polymerase (PARP) inhibitors. Acta Pharmacol Sin 2017. [PMID: 28414200 DOI: 10.1038/aps.2017.8]+[] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Over half of patients with BRCA1-deficient cancers do not respond to treatment with poly(ADP-ribose) polymerase (PARP) inhibitors. In this study, we report that a combination of 53BP1 and BRCA1 may serve as a biomarker of PARP inhibitor sensitivity. Based on the mRNA levels of four homologous recombination repair (HR) genes and PARP inhibitor sensitivity, we selected BRCA1-deficient MDA-MB-436 cells to conduct RNA interference. Reducing expression of 53BP1, but not the other three HR genes, was found to lower simmiparib sensitivity. Additionally, we generated 53BP1-/-/BRCA1-/- clonal variants by the transcription activator-like effector nuclease (TALEN) technique and found that depleting 53BP1 impaired PARP inhibitor sensitivity with a 36.7-fold increase in their IC50 values. Consistent with its effect on PARP inhibitor sensitivity, 53BP1 loss alleviated cell cycle arrest and apoptosis and partially restored HR function. Importantly, 53BP1 depletion dramatically reduced the ability of PARP inhibitors to suppress tumor growth in vivo. The inhibition rate of simmiparib was 74.16% for BRCA1-deficient MDA-MB-436 xenografts, but only 7.79% for 53BP1/BRCA1-deficient xenografts. Re-expressing 53BP1 in the dual-deficient cells restored PARP inhibitor sensitivity and the levels of HR regulators. Considering that at least 10% of BRCA1-deficient breast and ovarian cancers have reduced expression of 53BP1, using a combination of 53BP1 with BRCA1 as a biomarker for patient selection should reduce the number of patients undergoing futile treatment with PARP inhibitors.
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12
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Ali SO, Khan FA, Galindo-Campos MA, Yélamos J. Understanding specific functions of PARP-2: new lessons for cancer therapy. Am J Cancer Res 2016; 6:1842-1863. [PMID: 27725894 PMCID: PMC5043098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 08/31/2016] [Indexed: 06/06/2023] Open
Abstract
Poly(ADP-ribosyl)ation (PARylation) is a widespread and highly conserved post-translational modification catalysed by a large family of enzymes called poly(ADP-ribose) polymerases (PARPs). PARylation plays an essential role in various cardinal processes of cellular physiology and recent approvals and breakthrough therapy designations for PARP inhibitors in cancer therapy have sparked great interest in pharmacological targeting of PARP proteins. Although, many PARP inhibitors have been developed, existing compounds display promiscuous inhibition across the PARP superfamily which could lead to unwanted off-target effects. Thus the prospect of isoform-selective inhibition is being increasingly explored and research is now focusing on understanding specific roles of PARP family members. PARP-2, alongside PARP-1 and PARP-3 are the only known DNA damage-dependent PARPs and play critical roles in the DNA damage response, DNA metabolism and chromatin architecture. However, growing evidence shows that PARP-2 plays specific and diverse regulatory roles in cellular physiology, ranging from genomic stability and epigenetics to proliferative signalling and inflammation. The emerging network of PARP-2 target proteins has uncovered wide-ranging functions of the molecule in many cellular processes commonly dysregulated in carcinogenesis. Here, we review novel PARP-2-specific functions in the hallmarks of cancer and consider the implications for the development of isoform-selective inhibitors in chemotherapy. By considering the roles of PARP-2 through the lens of tumorigenesis, we propose PARP-2-selective inhibition as a potentially multipronged attack on cancer physiology.
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Affiliation(s)
- Syed O Ali
- School of Clinical Medicine, University of CambridgeCambridge, UK
| | - Farhaan A Khan
- School of Clinical Medicine, University of CambridgeCambridge, UK
| | - Miguel A Galindo-Campos
- Department of Immunology, Cancer Research Program, Institut Hospital del Mar d’Investigacions Mèdiques (IMIM)Barcelona, Spain
| | - José Yélamos
- Department of Immunology, Cancer Research Program, Institut Hospital del Mar d’Investigacions Mèdiques (IMIM)Barcelona, Spain
- CIBERehdSpain
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13
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Robust reprogramming of Ataxia-Telangiectasia patient and carrier erythroid cells to induced pluripotent stem cells. Stem Cell Res 2016; 17:296-305. [DOI: 10.1016/j.scr.2016.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 07/29/2016] [Accepted: 08/06/2016] [Indexed: 12/18/2022] Open
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14
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Ghosh R, Roy S, Kamyab J, Danzter F, Franco S. Common and unique genetic interactions of the poly(ADP-ribose) polymerases PARP1 and PARP2 with DNA double-strand break repair pathways. DNA Repair (Amst) 2016; 45:56-62. [PMID: 27373144 DOI: 10.1016/j.dnarep.2016.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 06/01/2016] [Accepted: 06/02/2016] [Indexed: 12/17/2022]
Abstract
In mammalian cells, chromatin poly(ADP-ribos)ylation (PARylation) at sites of DNA Double-Strand Breaks (DSBs) is mediated by two highly related enzymes, PARP1 and PARP2. However, enzyme-specific genetic interactions with other DSB repair factors remain largely undefined. In this context, it was previously shown that mice lacking PARP1 and H2AX, a histone variant that promotes DSB repair throughout the cell cycle, or the core nonhomologous end-joining (NHEJ) factor Ku80 are not viable, while mice lacking PARP1 and the noncore NHEJ factor DNA-PKcs are severely growth retarded and markedly lymphoma-prone. Here, we have examined the requirement for PARP2 in these backgrounds. We find that, like PARP1, PARP2 is essential for viability in mice lacking H2AX. Moreover, treatment of H2AX-deficient primary fibroblasts or B lymphocytes with PARP inhibitors leads to activation of the G2/M checkpoint and accumulation of chromatid-type breaks in a lineage- and gene-dose dependent manner. In marked contrast to PARP1, loss of PARP2 does not result in additional phenotypes in growth, development or tumorigenesis in mice lacking either Ku80 or DNA-PKcs. Altogether these findings highlight specific nonoverlapping functions of PARP1 and PARP2 at H2AX-deficient chromatin during replicative phases of the cell cycle and uncover a unique requirement for PARP1 in NHEJ-deficient cells.
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Affiliation(s)
- Rajib Ghosh
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins School of Medicine, Baltimore, MD 21287, United States
| | - Sanchita Roy
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins School of Medicine, Baltimore, MD 21287, United States
| | - Johan Kamyab
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins School of Medicine, Baltimore, MD 21287, United States
| | - Francoise Danzter
- Biotechnology and Cell Signaling Unit, University of Strasbourg, 67412 Illkirch, France
| | - Sonia Franco
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins School of Medicine, Baltimore, MD 21287, United States
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15
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Ying S, Chen Z, Medhurst AL, Neal JA, Bao Z, Mortusewicz O, McGouran J, Song X, Shen H, Hamdy FC, Kessler BM, Meek K, Helleday T. DNA-PKcs and PARP1 Bind to Unresected Stalled DNA Replication Forks Where They Recruit XRCC1 to Mediate Repair. Cancer Res 2015; 76:1078-88. [PMID: 26603896 DOI: 10.1158/0008-5472.can-15-0608] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 09/12/2015] [Indexed: 12/12/2022]
Abstract
A series of critical pathways are responsible for the detection, signaling, and restart of replication forks that encounter blocks during S-phase progression. Small base lesions may obstruct replication fork progression and processing, but the link between repair of small lesions and replication forks is unclear. In this study, we investigated a hypothesized role for DNA-PK, an important enzyme in DNA repair, in cellular responses to DNA replication stress. The enzyme catalytic subunit DNA-PKcs was phosphorylated on S2056 at sites of stalled replication forks in response to short hydroxyurea treatment. Using DNA fiber experiments, we found that catalytically active DNA-PK was required for efficient replication restart of stalled forks. Furthermore, enzymatically active DNA-PK was also required for PARP-dependent recruitment of XRCC1 to stalled replication forks. This activity was enhanced by preventing Mre11-dependent DNA end resection, suggesting that XRCC1 must be recruited early to an unresected stalled fork. We also found that XRCC1 was required for effective restart of a subset of stalled replication forks. Overall, our work suggested that DNA-PK and PARP-dependent recruitment of XRCC1 is necessary to effectively protect, repair, and restart stalled replication forks, providing new insight into how genomic stability is preserved.
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Affiliation(s)
- Songmin Ying
- Department of Respiratory and Critical Care Medicine of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China.
| | - Zhihui Chen
- Department of Gastrointestinal and Pancreatic Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Annette L Medhurst
- Department of Oncology, CR-UK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Jessica A Neal
- Department of Microbiology & Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan. Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan
| | - Zhengqiang Bao
- Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, China
| | - Oliver Mortusewicz
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Joanna McGouran
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford, United Kingdom
| | - Xinming Song
- Department of Gastrointestinal and Pancreatic Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Huahao Shen
- Department of Respiratory and Critical Care Medicine of Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. State Key Laboratory for Respiratory Diseases, Guangzhou, China
| | - Freddie C Hamdy
- Nuffield Department of Surgical Sciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Benedikt M Kessler
- Nuffield Department of Medicine, Henry Wellcome Building for Molecular Physiology, University of Oxford, Oxford, United Kingdom
| | - Katheryn Meek
- Department of Microbiology & Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan. Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan
| | - Thomas Helleday
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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16
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Zhou X, Ma X, Wang Z, Sun C, Wang Y, He Y, Zhang H. Radiation-induced hyperproliferation of intestinal crypts results in elevated genome instability with inactive p53-related genomic surveillance. Life Sci 2015; 143:80-8. [PMID: 26514305 DOI: 10.1016/j.lfs.2015.10.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 10/20/2015] [Accepted: 10/23/2015] [Indexed: 12/12/2022]
Abstract
AIMS Radiation-induced hyperproliferation of intestinal crypts is well documented, but its potential tumorigenic effects remain elusive. Here we aim to determine the genomic surveillance process during crypt hyperproliferation, and its consequential outcome after ionizing radiation. MAIN METHODS Crypt regeneration in the intestine was induced by a single dose of 12Gy abdominal irradiation. γ-H2AX, 53BP1 and DNA-PKcs were used as DNA repair surrogates to investigate the inherent ability of intestinal crypt cells to recognize and repair double-strand breaks. Ki67 staining and the 5-bromo-2'-deoxyuridine incorporation assay were used to study patterns of cell proliferation in regenerating crypts. Staining for ATM, p53, Chk1 and Chk2 was performed to study checkpoint activation and release. Apoptosis was evaluated through H&E staining and terminal deoxynucleotidyl transferase (dUTP) nick-end labeling. KEY FINDINGS The ATM-p53 pathway was immediately activated after irradiation. A second wave of DSBs in crypt cells was observed in regenerating crypts, accompanied with significantly increased chromosomal bridges. The p53-related genomic surveillance pathway was not active during the regeneration phase despite DSBs and chromosomal bridges in the cells of regenerating crypts. Non-homologous end joining (NHEJ) DSBs repair was involved in the DSBs repair process, as indicated by p-DNA-PKcs staining. SIGNIFICANCE Intestinal crypt cells retained hyperproliferation with inactive p53-related genomic surveillance system. NHEJ was involved in the resultant genomic instability during hyperproliferation.
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Affiliation(s)
- Xin Zhou
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China
| | - Xiaofei Ma
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; The School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 10049, PR China; The National Laboratory for the Heavy Ion Research Facility in Lanzhou, Lanzhou 730000, PR China
| | - Zhenhua Wang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China
| | - Chao Sun
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 10049, PR China
| | - Yupei Wang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 10049, PR China; The National Laboratory for the Heavy Ion Research Facility in Lanzhou, Lanzhou 730000, PR China
| | - Yang He
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 10049, PR China; The National Laboratory for the Heavy Ion Research Facility in Lanzhou, Lanzhou 730000, PR China
| | - Hong Zhang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China; Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou 730000, PR China; The National Laboratory for the Heavy Ion Research Facility in Lanzhou, Lanzhou 730000, PR China.
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17
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Rybanska-Spaeder I, Ghosh R, Franco S. 53BP1 mediates the fusion of mammalian telomeres rendered dysfunctional by DNA-PKcs loss or inhibition. PLoS One 2014; 9:e108731. [PMID: 25264618 PMCID: PMC4181871 DOI: 10.1371/journal.pone.0108731] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 09/04/2014] [Indexed: 12/21/2022] Open
Abstract
Telomere dysfunction promotes genomic instability and carcinogenesis via inappropriate end-to-end chromosomal rearrangements, or telomere fusions. Previous work indicates that the DNA Damage Response (DDR) factor 53BP1 promotes the fusion of telomeres rendered dysfunctional by loss of TRF2, but is dispensable for the fusion of telomeres lacking Pot1 or critically shortened (in telomerase-deficient mice). Here, we examine a role for 53BP1 at telomeres rendered dysfunctional by loss or catalytic inhibition of DNA-PKcs. Using mouse embryonic fibroblasts lacking 53BP1 and/or DNA-PKcs, we show that 53BP1 deficiency suppresses G1-generated telomere fusions that normally accumulate in DNA-PKcs-deficient fibroblasts with passage. Likewise, we find that 53BP1 promotes telomere fusions during the replicative phases of the cell cycle in cells treated with the specific DNA-PKcs inhibitor NU7026. However, telomere fusions are not fully abrogated in DNA-PKcs-inhibited 53BP1-deficient cells, but occur with a frequency approximately 10-fold lower than in control 53BP1-proficient cells. Treatment with PARP inhibitors or PARP1 depletion abrogates residual fusions, while Ligase IV depletion has no measurable effect, suggesting that PARP1-dependent alternative end-joining operates at low efficiency at 53BP1-deficient, DNA-PKcs-inhibited telomeres. Finally, we have also examined the requirement for DDR factors ATM, MDC1 or H2AX in this context. We find that ATM loss or inhibition has no measurable effect on the frequency of NU7026-induced fusions in wild-type MEFs. Moreover, analysis of MEFs lacking both ATM and 53BP1 indicates that ATM is also dispensable for telomere fusions via PARP-dependent end-joining. In contrast, loss of either MDC1 or H2AX abrogates telomere fusions in response to DNA-PKcs inhibition, suggesting that these factors operate upstream of both 53BP1-dependent and -independent telomere rejoining. Together, these experiments define a novel requirement for 53BP1 in the fusions of DNA-PKcs-deficient telomeres throughout the cell cycle and uncover a Ligase IV-independent, PARP1-dependent pathway that fuses telomeres at reduced efficiency in the absence of 53BP1.
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Affiliation(s)
- Ivana Rybanska-Spaeder
- Department of Radiation Oncology and Molecular Radiation Sciences; and Department of Oncology; and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Rajib Ghosh
- Department of Radiation Oncology and Molecular Radiation Sciences; and Department of Oncology; and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Sonia Franco
- Department of Radiation Oncology and Molecular Radiation Sciences; and Department of Oncology; and the Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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18
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Beck C, Robert I, Reina-San-Martin B, Schreiber V, Dantzer F. Poly(ADP-ribose) polymerases in double-strand break repair: focus on PARP1, PARP2 and PARP3. Exp Cell Res 2014; 329:18-25. [PMID: 25017100 DOI: 10.1016/j.yexcr.2014.07.003] [Citation(s) in RCA: 216] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Revised: 06/24/2014] [Accepted: 07/01/2014] [Indexed: 10/25/2022]
Abstract
Poly(ADP-ribosyl)ation (PARylation) is a post-translational modification of proteins catalysed by Poly(ADP-ribose) polymerases (PARP). A wealth of recent advances in the biochemical and functional characterization of the DNA-dependent PARP family members have highlighted their key contribution in the DNA damage response network, the best characterized being the role of PARP1 and PARP2 in the resolution of single-strand breaks as part of the BER/SSBR process. How PARylation contributes to the repair of double-strand breaks is less well defined but has become recently the subject of significant research in the field. The aim of this review is to provide an overview of the current knowledge concerning the role of the DNA-activated PARP1, PARP2 and PARP3 in cellular response to double-strand breaks (DSB). In addition, we outline the biological significance of these properties in response to programmed DNA lesions formed during physiological processes such as antibody repertoire assembly and diversification.
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Affiliation(s)
- Carole Beck
- Poly(ADP-ribosyl)ation and Genome Integrity, Equipe labellisée Ligue Nationale Contre Le Cancer, Laboratoire d׳Excellence Medalis, UMR7242, Centre National de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l׳Ecole de Biotechnologie de Strasbourg, bld. S. Brant, BP10413,67412 Illkirch, France
| | - Isabelle Robert
- Institut de Génétique et de Biologie Moléculaire et Cellulaire; Institut National de la Santé et de la Recherche Médicale, U964; Centre National de la Recherche Scientifique, UMR7104; Université de Strasbourg; Illkirch, 67400, France
| | - Bernardo Reina-San-Martin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire; Institut National de la Santé et de la Recherche Médicale, U964; Centre National de la Recherche Scientifique, UMR7104; Université de Strasbourg; Illkirch, 67400, France
| | - Valérie Schreiber
- Poly(ADP-ribosyl)ation and Genome Integrity, Equipe labellisée Ligue Nationale Contre Le Cancer, Laboratoire d׳Excellence Medalis, UMR7242, Centre National de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l׳Ecole de Biotechnologie de Strasbourg, bld. S. Brant, BP10413,67412 Illkirch, France
| | - Françoise Dantzer
- Poly(ADP-ribosyl)ation and Genome Integrity, Equipe labellisée Ligue Nationale Contre Le Cancer, Laboratoire d׳Excellence Medalis, UMR7242, Centre National de la Recherche Scientifique/Université de Strasbourg, Institut de Recherche de l׳Ecole de Biotechnologie de Strasbourg, bld. S. Brant, BP10413,67412 Illkirch, France.
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19
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Sasaki MS, Tachibana A, Takeda S. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors. JOURNAL OF RADIATION RESEARCH 2014; 55:391-406. [PMID: 24366315 PMCID: PMC4014156 DOI: 10.1093/jrr/rrt133] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 10/20/2013] [Accepted: 10/22/2013] [Indexed: 06/03/2023]
Abstract
Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to (239)Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation-environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking.
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Affiliation(s)
- Masao S. Sasaki
- Kyoto University, 17-12 Shironosato, Nagaokakyo-shi, Kyoto 617-0835, Japan
| | - Akira Tachibana
- Department of Biology, Faculty of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512, Japan
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-konoecho, Sakyo-ku, Kyoto 606-8501, Japan
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20
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RNF168 ubiquitylates 53BP1 and controls its response to DNA double-strand breaks. Proc Natl Acad Sci U S A 2013; 110:20982-7. [PMID: 24324146 DOI: 10.1073/pnas.1320302111] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Defective signaling or repair of DNA double-strand breaks has been associated with developmental defects and human diseases. The E3 ligase RING finger 168 (RNF168), mutated in the human radiosensitivity, immunodeficiency, dysmorphic features, and learning difficulties syndrome, was shown to ubiquitylate H2A-type histones, and this ubiquitylation was proposed to facilitate the recruitment of p53-binding protein 1 (53BP1) to the sites of DNA double-strand breaks. In contrast to more upstream proteins signaling DNA double-strand breaks (e.g., RNF8), deficiency of RNF168 fully prevents both the initial recruitment to and retention of 53BP1 at sites of DNA damage; however, the mechanism for this difference has remained unclear. Here, we identify mechanisms that regulate 53BP1 recruitment to the sites of DNA double-strand breaks and provide evidence that RNF168 plays a central role in the regulation of 53BP1 functions. RNF168 mediates K63-linked ubiquitylation of 53BP1 which is required for the initial recruitment of 53BP1 to sites of DNA double-strand breaks and for its function in DNA damage repair, checkpoint activation, and genomic integrity. Our findings highlight the multistep roles of RNF168 in signaling DNA damage.
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21
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Rybanska-Spaeder I, Reynolds TL, Chou J, Prakash M, Jefferson T, Huso DL, Desiderio S, Franco S. 53BP1 is limiting for NHEJ repair in ATM-deficient model systems that are subjected to oncogenic stress or radiation. Mol Cancer Res 2013; 11:1223-34. [PMID: 23858098 DOI: 10.1158/1541-7786.mcr-13-0252-t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
UNLABELLED The DNA damage response (DDR) factors ataxia telangiectasia mutated (ATM) and p53 binding protein 1 (53BP1) function as tumor suppressors in humans and mice, but the significance of their mutual interaction to the suppression of oncogenic translocations in vivo has not been investigated. To address this question, the phenotypes of compound mutant mice lacking 53BP1 and ATM (Trp53bp1(-/-)/Atm(-/-)), relative to single mutants, were examined. These analyses revealed that loss of 53BP1 markedly decreased the latency of T-lineage lymphomas driven by RAG-dependent oncogenic translocations in Atm(-/-) mice (average survival, 14 and 23 weeks for Trp53bp1(-/-)/Atm(-/-) and Atm(-/-) mice, respectively). Mechanistically, 53BP1 deficiency aggravated the deleterious effect of ATM deficiency on nonhomologous end-joining (NHEJ)-mediated double-strand break repair. Analysis of V(D)J recombinase-mediated coding joints and signal joints in Trp53bp1(-/-)/Atm(-/-) primary thymocytes is, however, consistent with canonical NHEJ-mediated repair. Together, these findings indicate that the greater NHEJ defect in the double mutant mice resulted from decreased efficiency of rejoining rather than switching to an alternative NHEJ-mediated repair mechanism. Complementary analyses of irradiated primary cells indicated that defects in cell-cycle checkpoints subsequently function to amplify the NHEJ defect, resulting in more frequent chromosomal breaks and translocations in double mutant cells throughout the cell cycle. Finally, it was determined that 53BP1 is dispensable for the formation of RAG-mediated hybrid joints in Atm(-/-) thymocytes but is required to suppress large deletions in a subset of hybrid joints. IMPLICATIONS The current study uncovers novel ATM-independent functions for 53BP1 in the suppression of oncogenic translocations and in radioprotection.
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Affiliation(s)
- Ivana Rybanska-Spaeder
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, 1550 Orleans Street, CRB II, Rm#405, Baltimore, MD 21287.
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Touching base with PARPs: moonlighting in the repair of UV lesions and double-strand breaks. Trends Biochem Sci 2013; 38:321-30. [PMID: 23562323 DOI: 10.1016/j.tibs.2013.03.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 12/13/2022]
Abstract
Distinct types of DNA damage elicit signaling and repair pathways that counteract the adverse effect of DNA lesions to maintain genome stability. The negatively charged polymer poly(ADP-ribose), which is catalyzed by poly(ADP-ribose) polymerase (PARP) enzymes, is a post-translational modification that serves as a chromatin-based platform for the recruitment of a variety of repair factors and chromatin-remodeling enzymes. Recent work implicates PARP3 in the efficient joining of DNA double-strand breaks during non-homologous end-joining (NHEJ), whereas PARP1 modulates the repair of UV-induced DNA lesions. Here we discuss emerging roles of PARP enzymes in mechanistically distinct DNA repair pathways and highlight unresolved issues and questions for future research.
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23
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Rass E, Chandramouly G, Zha S, Alt FW, Xie A. Ataxia telangiectasia mutated (ATM) is dispensable for endonuclease I-SceI-induced homologous recombination in mouse embryonic stem cells. J Biol Chem 2013; 288:7086-95. [PMID: 23355489 DOI: 10.1074/jbc.m112.445825] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ataxia telangiectasia mutated (ATM) is activated upon DNA double strand breaks (DSBs) and phosphorylates numerous DSB response proteins, including histone H2AX on serine 139 (Ser-139) to form γ-H2AX. Through interaction with MDC1, γ-H2AX promotes DSB repair by homologous recombination (HR). H2AX Ser-139 can also be phosphorylated by DNA-dependent protein kinase catalytic subunit and ataxia telangiectasia- and Rad3-related kinase. Thus, we tested whether ATM functions in HR, particularly that controlled by γ-H2AX, by comparing HR occurring at the euchromatic ROSA26 locus between mouse embryonic stem cells lacking either ATM, H2AX, or both. We show here that loss of ATM does not impair HR, including H2AX-dependent HR, but confers sensitivity to inhibition of poly(ADP-ribose) polymerases. Loss of ATM or H2AX has independent contributions to cellular sensitivity to ionizing radiation. The ATM-independent HR function of H2AX requires both Ser-139 phosphorylation and γ-H2AX/MDC1 interaction. Our data suggest that ATM is dispensable for HR, including that controlled by H2AX, in the context of euchromatin, excluding the implication of such an HR function in genomic instability, hypersensitivity to DNA damage, and poly(ADP-ribose) polymerase inhibition associated with ATM deficiency.
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Affiliation(s)
- Emilie Rass
- Department of Medicine, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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PARP1 and DNA-PKcs synergize to suppress p53 mutation and telomere fusions during T-lineage lymphomagenesis. Oncogene 2012; 32:1761-71. [PMID: 22614020 DOI: 10.1038/onc.2012.199] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Poly(ADP-ribose) polymerase 1 (PARP1) interacts genetically with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to suppress early-onset T-lineage lymphomas in the mouse, but the underlying mechanisms have remained unknown. To address this question, we analyzed a series of lymphomas arising in PARP1(-/-)/DNA-PKcs(-/-) (P1(-/-)/D(-/-)) mice. We found that, despite defective V(D)J recombination, P1(-/-)/D(-/-) lymphomas lacked clonal reciprocal translocations involving antigen-receptor loci. Instead, tumor cells were characterized by aneuploidy driven by two main mechanisms: p53 inactivation and abnormal chromosome disjunction due to telomere fusions (TFs). Aberrant accumulation of p53 was observed in 13/19 (68.4%) lymphomas. Sequence analysis revealed five p53 mutations: three missense point mutations (one transition in exon 8 and two transversions in exons 5 and 8, respectively), one in-frame 5-11 microindel in exon 7 and a 410-bp deletion encompassing exons 5-8, resulting in a truncated protein. Analysis of tumor metaphases using sequential telomere fluorescent in-situ hybridization and spectral karyotyping revealed that nine out of nine lymphomas contained TFs. Mutant but not wild-type p53 status was associated with frequent clonal and nonclonal TFs, suggesting that p53 normally limits the extent of telomere dysfunction during transformation. Chromosomes involved in TFs were more likely to be aneuploid than chromosomes not involved in TFs in the same metaphases, regardless of the p53 status, indicating that TFs promote aneuploidy via a mechanism that is distinct from p53 loss. Finally, analysis of radiation responses in P1(-/-)/D(-/-), and control primary cells and tissues indicates that loss of PARP1 increases in vivo radiosensitivity and genomic instability in DNA-PKcs-deficient mice without impairing p53 stabilization and effector functions, suggesting a more severe defect in double-strand break (DSB) repair in double mutants. Together, our findings uncover defective DSB repair leading to tumor suppressor inactivation and abnormal segregation of fused chromosomes as two novel mechanisms promoting tumorigenesis in thymocytes lacking PARP1 and DNA-PKcs.
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Lang J, Smetana O, Sanchez-Calderon L, Lincker F, Genestier J, Schmit AC, Houlné G, Chabouté ME. Plant γH2AX foci are required for proper DNA DSB repair responses and colocalize with E2F factors. THE NEW PHYTOLOGIST 2012; 194:353-363. [PMID: 22339405 DOI: 10.1111/j.1469-8137.2012.04062.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Cellular responses to DNA double-strand breaks (DSBs) are linked in mammals and yeasts to the phosphorylated histones H2AX (γH2AX) repair foci which are multiproteic nuclear complexes responsible for DSB sensing and signalling. However, neither the components of these foci nor their role are yet known in plants. In this paper, we describe the effects of γH2AX deficiency in Arabidopsis thaliana plants challenged with DSBs in terms of genotoxic sensitivity and E2F-mediated transcriptional responses. We further establish the existence, restrictive to the G1/S transition, of specific DSB-induced foci containing tobacco E2F transcription factors, in both A. thaliana roots and BY-2 tobacco cells. These E2F foci partially colocalize with γH2AX foci while their formation is ataxia telangiectasia mutated (ATM)-dependent, requires the E2F transactivation domain with its retinoblastoma-binding site and is optimal in the presence of functional H2AXs. Overall, our results unveil a new interplay between plant H2AX and E2F transcriptional activators during the DSB response.
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Affiliation(s)
- Julien Lang
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - Ondrej Smetana
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - Lenin Sanchez-Calderon
- Laboratorio de Biología Molecular de Plantas Unidad Académica de Biología Experimental Universidad Autónoma de Zacatecas, Av. Revolución S/N Col. Tierra y Libertad CP, 98615 Guadalupe, Zacatecas, México
| | - Frédéric Lincker
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - Julie Genestier
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - Anne-Catherine Schmit
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - Guy Houlné
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes, laboratoire propre du CNRS, (UPR 2357) conventionné avec l'Université de Strasbourg 12, rue du Général Zimmer, 67084 Strasbourg Cedex, France
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Fink LS, Roell M, Caiazza E, Lerner C, Stamato T, Hrelia S, Lorenzini A, Sell C. 53BP1 contributes to a robust genomic stability in human fibroblasts. Aging (Albany NY) 2012; 3:836-45. [PMID: 21931182 PMCID: PMC3227449 DOI: 10.18632/aging.100381] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Faithful repair of damaged DNA is a crucial process in maintaining cell viability and function. A multitude of factors and pathways guides this process and includes repair proteins and cell cycle checkpoint factors. Differences in the maintenance of genomic processes are one feature that may contribute to species-specific differences in lifespan. We predicted that 53BP1, a key transducer of the DNA damage response and cell cycle checkpoint control, is highly involved in maintaining genomic stability and may function differently in cells from different species. We demonstrate a difference in the levels and recruitment of 53BP1 in mouse and human cells following DNA damage. In addition, we show that unresolved DNA damage persists more in mouse cells than in human cells, as evidenced by increased numbers of micronuclei. The difference in micronuclei seems to be related to the levels of 53BP1 present in cells. Finally, we present evidence that unresolved DNA damage correlates with species lifespan. Taken together, these studies suggest a link between recruitment of 53BP1, resolution of DNA damage, and increased species lifespan.
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Affiliation(s)
- Lauren S Fink
- Department of Pathology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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27
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Nonhomologous end joining drives poly(ADP-ribose) polymerase (PARP) inhibitor lethality in homologous recombination-deficient cells. Proc Natl Acad Sci U S A 2011; 108:3406-11. [PMID: 21300883 DOI: 10.1073/pnas.1013715108] [Citation(s) in RCA: 405] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Poly(ADP-ribose) polymerase (PARP) inhibitors are strikingly toxic to cells with defects in homologous recombination (HR). The mechanistic basis for these findings is incompletely understood. Here, we show that PARP inhibitor treatment induces phosphorylation of DNA-dependent protein kinase substrates and stimulates error-prone nonhomologous end joining (NHEJ) selectively in HR-deficient cells. Notably, inhibiting DNA-dependent protein kinase activity reverses the genomic instability previously reported in these cells after PARP inhibition. Moreover, disabling NHEJ by using genetic or pharmacologic approaches rescues the lethality of PARP inhibition or down-regulation in cell lines lacking BRCA2, BRCA1, or ATM. Collectively, our results not only implicate PARP1 catalytic activity in the regulation of NHEJ in HR-deficient cells, but also indicate that deregulated NHEJ plays a major role in generating the genomic instability and cytotoxicity in HR-deficient cells treated with PARP inhibitors.
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Nijman SMB. Synthetic lethality: general principles, utility and detection using genetic screens in human cells. FEBS Lett 2010; 585:1-6. [PMID: 21094158 PMCID: PMC3018572 DOI: 10.1016/j.febslet.2010.11.024] [Citation(s) in RCA: 205] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 11/10/2010] [Indexed: 12/14/2022]
Abstract
Synthetic lethality occurs when the simultaneous perturbation of two genes results in cellular or organismal death. Synthetic lethality also occurs between genes and small molecules, and can be used to elucidate the mechanism of action of drugs. This area has recently attracted attention because of the prospect of a new generation of anti-cancer drugs. Based on studies ranging from yeast to human cells, this review provides an overview of the general principles that underlie synthetic lethality and relates them to its utility for identifying gene function, drug action and cancer therapy. It also identifies the latest strategies for the large-scale mapping of synthetic lethalities in human cells which bring us closer to the generation of comprehensive human genetic interaction maps.
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Affiliation(s)
- Sebastian M B Nijman
- Research Center for Molecular Medicine of the Austrian Academy of Sciences (CeMM), Vienna, Austria.
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Yuan J, Adamski R, Chen J. Focus on histone variant H2AX: to be or not to be. FEBS Lett 2010; 584:3717-24. [PMID: 20493860 DOI: 10.1016/j.febslet.2010.05.021] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 05/04/2010] [Accepted: 05/11/2010] [Indexed: 12/16/2022]
Abstract
Phosphorylation of histone variant H2AX at serine 139, named gammaH2AX, has been widely used as a sensitive marker for DNA double-strand breaks (DSBs). gammaH2AX is required for the accumulation of many DNA damage response (DDR) proteins at DSBs. Thus it is believed to be the principal signaling protein involved in DDR and to play an important role in DNA repair. However, only mild defects in DNA damage signaling and DNA repair were observed in H2AX-deficient cells and animals. Such findings prompted us and others to explore H2AX-independent mechanisms in DNA damage response. Here, we will review recent advances in our understanding of H2AX-dependent and independent DNA damage signaling and repair pathways in mammalian cells.
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Affiliation(s)
- Jingsong Yuan
- Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
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