151
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Awwad SW, Abu-Zhayia ER, Guttmann-Raviv N, Ayoub N. NELF-E is recruited to DNA double-strand break sites to promote transcriptional repression and repair. EMBO Rep 2017; 18:745-764. [PMID: 28336775 PMCID: PMC5412775 DOI: 10.15252/embr.201643191] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 02/07/2017] [Accepted: 02/08/2017] [Indexed: 01/12/2023] Open
Abstract
Double-strand breaks (DSBs) trigger rapid and transient transcription pause to prevent collisions between repair and transcription machineries at damage sites. Little is known about the mechanisms that ensure transcriptional block after DNA damage. Here, we reveal a novel role of the negative elongation factor NELF in blocking transcription activity nearby DSBs. We show that NELF-E and NELF-A are rapidly recruited to DSB sites. Furthermore, NELF-E recruitment and its repressive activity are both required for switching off transcription at DSBs. Remarkably, using I-SceI endonuclease and CRISPR-Cas9 systems, we observe that NELF-E is preferentially recruited, in a PARP1-dependent manner, to DSBs induced upstream of transcriptionally active rather than inactive genes. Moreover, the presence of RNA polymerase II is a prerequisite for the preferential recruitment of NELF-E to DNA break sites. Additionally, we demonstrate that NELF-E is required for intact repair of DSBs. Altogether, our data identify the NELF complex as a new component in the DNA damage response.
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Affiliation(s)
- Samah W Awwad
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Enas R Abu-Zhayia
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Noga Guttmann-Raviv
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Nabieh Ayoub
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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152
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Garschall K, Dellago H, Gáliková M, Schosserer M, Flatt T, Grillari J. Ubiquitous overexpression of the DNA repair factor dPrp19 reduces DNA damage and extends Drosophila life span. NPJ Aging Mech Dis 2017. [PMID: 28649423 PMCID: PMC5445577 DOI: 10.1038/s41514-017-0005-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mechanisms that ensure and maintain the stability of genetic information are fundamentally important for organismal function and can have a large impact on disease, aging, and life span. While a multi-layered cellular apparatus exists to detect and respond to DNA damage, various insults from environmental and endogenous sources continuously affect DNA integrity. Over time this can lead to the accumulation of somatic mutations, which is thought to be one of the major causes of aging. We have previously found that overexpression of the essential human DNA repair and splicing factor SNEV, also called PRP19 or hPso4, extends replicative life span of cultured human endothelial cells and impedes accumulation of DNA damage. Here, we show that adult-specific overexpression of dPrp19, the D. melanogaster ortholog of human SNEV/PRP19/hPso4, robustly extends life span in female fruit flies. This increase in life span is accompanied by reduced levels of DNA damage and improved resistance to oxidative and genotoxic stress. Our findings suggest that dPrp19 plays an evolutionarily conserved role in aging, life span modulation and stress resistance, and support the notion that superior DNA maintenance is key to longevity. Increasing levels of DNA repair factor Prp19 in fruit flies extends their life span and protects against stress. Prp19 is a protein that is present in a wide range of organisms and enables human endothelial cells to live longer in vitro. In this article, an international team of scientists from Austria, Germany and Switzerland found that higher Prp19 levels also prolong the life span of a whole organism in fruit flies, reduce DNA damage and increase survival when exposed to DNA damaging compounds. In contrast to female flies, males were unaffected. Their findings support the long-held view that repair of DNA damage, one of the hallmarks of aging, is key to longevity. They also provide an intriguing but poorly understood connection between cellular aging and the survival of whole organisms.
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Affiliation(s)
- Kathrin Garschall
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Hanna Dellago
- Department of Biotechnology, BOKU - University of Natural Resources and Life Sciences, Vienna, Vienna, Austria
| | - Martina Gáliková
- Institut für Populationsgenetik, Vetmeduni Vienna, Vienna Austria.,Department of Developmental Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Markus Schosserer
- Department of Biotechnology, BOKU - University of Natural Resources and Life Sciences, Vienna, Vienna, Austria
| | - Thomas Flatt
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Institut für Populationsgenetik, Vetmeduni Vienna, Vienna Austria
| | - Johannes Grillari
- Department of Biotechnology, BOKU - University of Natural Resources and Life Sciences, Vienna, Vienna, Austria.,Christian Doppler Laboratory on Biotechnology of Skin Aging, Dept. of Biotechnology, BOKU - University of Natural Resources and Life Sciences, Vienna, Vienna, Austria.,Evercyte GmbH, Vienna, Austria
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153
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Khoronenkova SV. Mechanisms of Non-canonical Activation of Ataxia Telangiectasia Mutated. BIOCHEMISTRY (MOSCOW) 2017; 81:1669-1675. [PMID: 28260489 DOI: 10.1134/s0006297916130058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ATM is a master regulator of the cellular response to DNA damage. The classical mechanism of ATM activation involves its monomerization in response to DNA double-strand breaks, resulting in ATM-dependent phosphorylation of more than a thousand substrates required for cell cycle progression, DNA repair, and apoptosis. Here, new experimental evidence for non-canonical mechanisms of ATM activation in response to stimuli distinct from DNA double-strand breaks is discussed. It includes cytoskeletal changes, chromatin modifications, RNA-DNA hybrids, and DNA single-strand breaks. Noncanonical ATM activation may be important for the pathology of the multisystemic disease Ataxia Telangiectasia.
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Affiliation(s)
- S V Khoronenkova
- University of Cambridge, Department of Biochemistry, Cambridge, CB2 1GA, UK.
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154
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Su C, Zhao H, Zhao Y, Ji H, Wang Y, Zhi L, Li X. RUG3 and ATM synergistically regulate the alternative splicing of mitochondrial nad2 and the DNA damage response in Arabidopsis thaliana. Sci Rep 2017; 7:43897. [PMID: 28262819 PMCID: PMC5338318 DOI: 10.1038/srep43897] [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: 11/30/2016] [Accepted: 01/30/2017] [Indexed: 01/10/2023] Open
Abstract
The root apical meristem (RAM) determines both RAM activity and the growth of roots. Plant roots are constantly exposed to adverse environmental stresses that can cause DNA damage or cell cycle arrest in the RAM; however, the mechanism linking root meristematic activity and RAM size to the DNA damage response (DDR) is unclear. Here, we demonstrate that a loss of function in RCC1/UVR8/GEF-Like 3 (RUG3) substantially augmented the DDR and produced a cell cycle arrest in the RAM in rug3 mutant, leading to root growth retardation. Furthermore, the mutation of RUG3 caused increased intracellular reactive oxygen species (ROS) levels, and ROS scavengers improved the observed cell cycle arrest and reduced RAM activity level in rug3 plants. Most importantly, we detected a physical interaction between RUG3 and ataxia telangiectasia mutated (ATM), a key regulator of the DDR, suggesting that they synergistically modulated the alternative splicing of nad2. Our findings reveal a novel synergistic effect of RUG3 and ATM on the regulation of mitochondrial function, redox homeostasis, and the DDR in the RAM, and outline a protective mechanism for DNA damage repair and the restoration of mitochondrial function that involves RUG3-mediated mitochondrial retrograde signaling and the activation of an ATM-mediated DDR pathway.
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Affiliation(s)
- Chao Su
- State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology Huazhong Agricultural University, Wuhan 430070, P.R. China.,Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Hebei 050021, P.R. China
| | - Hongtao Zhao
- Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Hebei 050021, P.R. China.,College of Life Sciences, Hebei Normal University, Hebei 050024, P.R. China
| | - Yankun Zhao
- Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Hebei 050021, P.R. China.,Shijiazhuang Academy of Agricultural and Forestry Sciences, Hebei 050041, P.R. China
| | - Hongtao Ji
- State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology Huazhong Agricultural University, Wuhan 430070, P.R. China
| | - Youning Wang
- State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology Huazhong Agricultural University, Wuhan 430070, P.R. China
| | - Liya Zhi
- Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Hebei 050021, P.R. China
| | - Xia Li
- State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology Huazhong Agricultural University, Wuhan 430070, P.R. China
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155
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Replication Fork Protection Factors Controlling R-Loop Bypass and Suppression. Genes (Basel) 2017; 8:genes8010033. [PMID: 28098815 PMCID: PMC5295027 DOI: 10.3390/genes8010033] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/02/2017] [Accepted: 01/09/2017] [Indexed: 12/17/2022] Open
Abstract
Replication–transcription conflicts have been a well-studied source of genome instability for many years and have frequently been linked to defects in RNA processing. However, recent characterization of replication fork-associated proteins has revealed that defects in fork protection can directly or indirectly stabilize R-loop structures in the genome and promote transcription–replication conflicts that lead to genome instability. Defects in essential DNA replication-associated activities like topoisomerase, or the minichromosome maintenance (MCM) helicase complex, as well as fork-associated protection factors like the Fanconi anemia pathway, both appear to mitigate transcription–replication conflicts. Here, we will highlight recent advances that support the concept that normal and robust replisome function itself is a key component of mitigating R-loop coupled genome instability.
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156
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Marteijn JA, Vermeulen W, Tresini M. Noncanonical ATM Activation and Signaling in Response to Transcription-Blocking DNA Damage. Methods Mol Biol 2017; 1599:347-361. [PMID: 28477131 DOI: 10.1007/978-1-4939-6955-5_25] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Environmental genotoxins and metabolic byproducts generate DNA lesions that can cause genomic instability and disrupt tissue homeostasis. To ensure genomic integrity, cells employ mechanisms that convert signals generated by stochastic DNA damage into organized responses, including activation of repair systems, cell cycle checkpoints, and apoptotic mechanisms. DNA damage response (DDR) signaling pathways coordinate these responses and determine cellular fates in part, by transducing signals that modulate RNA metabolism. One of the master DDR coordinators, the Ataxia Telangiectasia Mutated (ATM) kinase, has a fundamental role in mediating DNA damage-induced changes in mRNA synthesis. ATM acts by modulating a variety of RNA metabolic pathways including nascent RNA splicing, a process catalyzed by the spliceosome. Interestingly, ATM and the spliceosome influence each other's activity in a reciprocal manner by a pathway that initiates when transcribing RNA polymerase II (RNAPII) encounters DNA lesions that prohibit forward translocation. In response to stalling of RNAPII assembly of late-stage spliceosomes is disrupted resulting in increased splicing factor mobility. Displacement of spliceosomes from lesion-arrested RNA polymerases facilitates formation of R-loops between the nascent RNA and DNA adjacent to the transcription bubble. R-loops signal for noncanonical ATM activation which in quiescent cells occurs in absence of detectable dsDNA breaks. In turn, activated ATM signals to regulate spliceosome dynamics and AS genome wide.This chapter describes the use of fluorescence microscopy methods that can be used to evaluate noncanonical ATM activation by transcription-blocking DNA damage. First, we present an immunofluorescence-detection method that can be used to evaluate ATM activation by autophosphorylation, in fixed cells. Second, we present a protocol for Fluorescence Recovery After Photobleaching (FRAP) of GFP-tagged splicing factors, a highly sensitive and reproducible readout to measure in living cells, the ATM influence on the spliceosome. These approaches have been extensively used in our laboratory for a number of cell lines of various origins and are particularly informative when used in primary cells that can be synchronized in quiescence, to avoid generation of replication stress-induced dsDNA breaks and consequent ATM activation through its canonical pathway.
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Affiliation(s)
- Jurgen A Marteijn
- Department of Molecular Genetics, Cancer Genomics Netherlands, Erasmus University Medical Center, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands
| | - Wim Vermeulen
- Department of Molecular Genetics, Cancer Genomics Netherlands, Erasmus University Medical Center, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands
| | - Maria Tresini
- Department of Molecular Genetics, Cancer Genomics Netherlands, Erasmus University Medical Center, Wytemaweg 80, 3015 CN, Rotterdam, The Netherlands.
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157
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Sridhara SC, Carvalho S, Grosso AR, Gallego-Paez LM, Carmo-Fonseca M, de Almeida SF. Transcription Dynamics Prevent RNA-Mediated Genomic Instability through SRPK2-Dependent DDX23 Phosphorylation. Cell Rep 2017; 18:334-343. [DOI: 10.1016/j.celrep.2016.12.050] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 11/13/2016] [Accepted: 12/14/2016] [Indexed: 10/20/2022] Open
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158
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The spliceosome U2 snRNP factors promote genome stability through distinct mechanisms; transcription of repair factors and R-loop processing. Oncogenesis 2016; 5:e280. [PMID: 27991914 PMCID: PMC5177769 DOI: 10.1038/oncsis.2016.70] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 10/02/2016] [Indexed: 12/12/2022] Open
Abstract
Recent whole-exome sequencing of malignancies have detected recurrent somatic mutations in U2 small nuclear ribonucleoprotein complex (snRNP) components of the spliceosome. These factors have also been identified as novel players in the DNA-damage response (DDR) in several genome-wide screens and proteomic analysis. Although accumulating evidence implies that the spliceosome has an important role in genome stability and is an emerging hallmark of cancer, its precise role in DNA repair still remains elusive. Here we identify two distinct mechanisms of how spliceosome U2 snRNP factors contribute to genome stability. We show that the spliceosome maintains protein levels of essential repair factors, thus contributing to homologous recombination repair. In addition, real-time laser microirradiation analysis identified rapid recruitment of the U2 snRNP factor SNRPA1 to DNA-damage sites. Functional analysis of SNRPA1 revealed a more immediate and direct role in preventing R-loop-induced DNA damage. Our present study implies a complex interrelation between transcription, mRNA splicing and the DDR. Cells require rapid spatio-temporal coordination of these chromatin transactions to cope with various forms of genotoxic stress.
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159
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Splicing factor gene mutations in hematologic malignancies. Blood 2016; 129:1260-1269. [PMID: 27940478 DOI: 10.1182/blood-2016-10-692400] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 11/25/2016] [Indexed: 01/27/2023] Open
Abstract
Alternative splicing generates a diversity of messenger RNA (mRNA) transcripts from a single mRNA precursor and contributes to the complexity of our proteome. Splicing is perturbed by a variety of mechanisms in cancer. Recurrent mutations in splicing factors have emerged as a hallmark of several hematologic malignancies. Splicing factor mutations tend to occur in the founding clone of myeloid cancers, and these mutations have recently been identified in blood cells from normal, healthy elderly individuals with clonal hematopoiesis who are at increased risk of subsequently developing a hematopoietic malignancy, suggesting that these mutations contribute to disease initiation. Splicing factor mutations change the pattern of splicing in primary patient and mouse hematopoietic cells and alter hematopoietic differentiation and maturation in animal models. Recent developments in this field are reviewed here, with an emphasis on the clinical consequences of splicing factor mutations, mechanistic insights from animal models, and implications for development of novel therapies targeting the precursor mRNA splicing pathway.
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160
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Steurer B, Marteijn JA. Traveling Rocky Roads: The Consequences of Transcription-Blocking DNA Lesions on RNA Polymerase II. J Mol Biol 2016; 429:3146-3155. [PMID: 27851891 DOI: 10.1016/j.jmb.2016.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/04/2016] [Accepted: 11/04/2016] [Indexed: 12/13/2022]
Abstract
The faithful transcription of eukaryotic genes by RNA polymerase II (RNAP2) is crucial for proper cell function and tissue homeostasis. However, transcription-blocking DNA lesions of both endogenous and environmental origin continuously challenge the progression of elongating RNAP2. The stalling of RNAP2 on a transcription-blocking lesion triggers a series of highly regulated events, including RNAP2 processing to make the lesion accessible for DNA repair, R-loop-mediated DNA damage signaling, and the initiation of transcription-coupled DNA repair. The correct execution and coordination of these processes is vital for resuming transcription following the successful repair of transcription-blocking lesions. Here, we outline recent insights into the molecular consequences of RNAP2 stalling on transcription-blocking DNA lesions and how these lesions are resolved to restore mRNA synthesis.
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Affiliation(s)
- Barbara Steurer
- Department of Molecular Genetics, Erasmus MC, Wytemaweg 80, Rotterdam 3015 CN, The Netherlands
| | - Jurgen A Marteijn
- Department of Molecular Genetics, Erasmus MC, Wytemaweg 80, Rotterdam 3015 CN, The Netherlands.
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161
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Mao P, Wyrick JJ. Emerging roles for histone modifications in DNA excision repair. FEMS Yeast Res 2016; 16:fow090. [PMID: 27737893 DOI: 10.1093/femsyr/fow090] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2016] [Indexed: 12/27/2022] Open
Abstract
DNA repair is critical to maintain genome stability. In eukaryotic cells, DNA repair is complicated by the packaging of the DNA 'substrate' into chromatin. DNA repair pathways utilize different mechanisms to overcome the barrier presented by chromatin to efficiently locate and remove DNA lesions in the genome. DNA excision repair pathways are responsible for repairing a majority of DNA lesions arising in the genome. Excision repair pathways include nucleotide excision repair (NER) and base excision repair (BER), which repair bulky and non-bulky DNA lesions, respectively. Numerous studies have suggested that chromatin inhibits both NER and BER in vitro and in vivo Growing evidence demonstrates that histone modifications have important roles in regulating the activity of NER and BER enzymes in chromatin. Here, we will discuss the roles of different histone modifications and the corresponding modifying enzymes in DNA excision repair, highlighting the role of yeast as a model organism for many of these studies.
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Affiliation(s)
- Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
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162
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Wang Y, Guan H, Xie DF, Xie Y, Liu XD, Wang Q, Sui L, Song M, Zhang H, Zhou J, Zhou PK. Proteomic Analysis Implicates Dominant Alterations of RNA Metabolism and the Proteasome Pathway in the Cellular Response to Carbon-Ion Irradiation. PLoS One 2016; 11:e0163896. [PMID: 27711237 PMCID: PMC5053480 DOI: 10.1371/journal.pone.0163896] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 09/18/2016] [Indexed: 12/25/2022] Open
Abstract
Radiotherapy with heavy ions is considered advantageous compared to irradiation with photons due to the characteristics of the Braggs peak and the high linear energy transfer (LET) value. To understand the mechanisms of cellular responses to different LET values and dosages of heavy ion radiation, we analyzed the proteomic profiles of mouse embryo fibroblast MEF cells exposed to two doses from different LET values of heavy ion 12C. Total proteins were extracted from these cells and examined by Q Exactive with Liquid Chromatography (LC)—Electrospray Ionization (ESI) Tandem MS (MS/MS). Using bioinformatics approaches, differentially expressed proteins with 1.5 or 2.0-fold changes between different dosages of exposure were compared. With the higher the dosage and/or LET of ion irradiation, the worse response the cells were in terms of protein expression. For instance, compared to the control (0 Gy), 771 (20.2%) proteins in cells irradiated at 0.2 Gy of carbon-ion radiation with 12.6 keV/μm, 313 proteins (8.2%) in cells irradiated at 2 Gy of carbon-ion radiation with 12.6 keV/μm, and 243 proteins (6.4%) in cells irradiated at 2 Gy of carbon-ion radiation with 31.5 keV/μm exhibited changes of 1.5-fold or greater. Gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Munich Information Center for Protein Sequences (MIPS) analysis, and BioCarta analysis all indicated that RNA metabolic processes (RNA splicing, destabilization and deadenylation) and proteasome pathways may play key roles in the cellular response to heavy-ion irradiation. Proteasome pathways ranked highest among all biological processes associated with heavy carbon-ion irradiation. In addition, network analysis revealed that cellular pathways involving proteins such as Col1a1 and Fn1 continued to respond to high dosages of heavy-ion irradiation, suggesting that these pathways still protect cells against damage. However, pathways such as those involving Ikbkg1 responded better at lower dosages than at higher dosages, implying that cell damage would occur when the networks involving these proteins stop responding. Our investigation provides valuable proteomic information for elucidating the mechanism of biological effects induced by carbon ions in general.
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Affiliation(s)
- Yu Wang
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Hua Guan
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Da-Fei Xie
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Yi Xie
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Xiao-Dan Liu
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Qi Wang
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Li Sui
- China Institute of Atomic Energy, Beijing 102413, China
| | - Man Song
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, School of Radiation Medicine and Protection, Soochow University, Suzhou, China
| | - Hong Zhang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Jianhua Zhou
- iBioinfo Groups, Lexington, Massachusetts 02421, United States of America
- Department of Neuroregeneration, Nantong University, Nantong, China
- * E-mail: (PKZ); (JZ)
| | - Ping-Kun Zhou
- Department of Radiation Toxicology and Oncology, Beijing Key Laboratory for Radiation Biology, Beijing Institute of Radiation Medicine, Beijing, China
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, School of Radiation Medicine and Protection, Soochow University, Suzhou, China
- * E-mail: (PKZ); (JZ)
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163
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DNA-Damage Response RNA-Binding Proteins (DDRBPs): Perspectives from a New Class of Proteins and Their RNA Targets. J Mol Biol 2016; 429:3139-3145. [PMID: 27693651 DOI: 10.1016/j.jmb.2016.09.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 11/23/2022]
Abstract
Upon DNA damage, cells trigger an early DNA-damage response (DDR) involving DNA repair and cell cycle checkpoints, and late responses involving gene expression regulation that determine cell fate. Screens for genes involved in the DDR have found many RNA-binding proteins (RBPs), while screens for novel RBPs have identified DDR proteins. An increasing number of RBPs are involved in early and/or late DDR. We propose to call this new class of actors of the DDR, which contain an RNA-binding activity, DNA-damage response RNA-binding proteins (DDRBPs). We then discuss how DDRBPs contribute not only to gene expression regulation in the late DDR but also to early DDR signaling, DNA repair, and chromatin modifications at DNA-damage sites through interactions with both long and short noncoding RNAs.
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164
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Why Cockayne syndrome patients do not get cancer despite their DNA repair deficiency. Proc Natl Acad Sci U S A 2016; 113:10151-6. [PMID: 27543334 DOI: 10.1073/pnas.1610020113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cockayne syndrome (CS) and xeroderma pigmentosum (XP) are human photosensitive diseases with mutations in the nucleotide excision repair (NER) pathway, which repairs DNA damage from UV exposure. CS is mutated in the transcription-coupled repair (TCR) branch of the NER pathway and exhibits developmental and neurological pathologies. The XP-C group of XP patients have mutations in the global genome repair (GGR) branch of the NER pathway and have a very high incidence of UV-induced skin cancer. Cultured cells from both diseases have similar sensitivity to UV-induced cytotoxicity, but CS patients have never been reported to develop cancer, although they often exhibit photosensitivity. Because cancers are associated with increased mutations, especially when initiated by DNA damage, we examined UV-induced mutagenesis in both XP-C and CS cells, using duplex sequencing for high-sensitivity mutation detection. Duplex sequencing detects rare mutagenic events, independent of selection and in multiple loci, enabling examination of all mutations rather than just those that confer major changes to a specific protein. We found telomerase-positive normal and CS-B cells had increased background mutation frequencies that decreased upon irradiation, purging the population of subclonal variants. Primary XP-C cells had increased UV-induced mutation frequencies compared with normal cells, consistent with their GGR deficiency. CS cells, in contrast, had normal levels of mutagenesis despite their TCR deficiency. The lack of elevated UV-induced mutagenesis in CS cells reveals that their TCR deficiency, although increasing cytotoxicity, is not mutagenic. Therefore the absence of cancer in CS patients results from the absence of UV-induced mutagenesis rather than from enhanced lethality.
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165
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Canonical DNA Repair Pathways Influence R-Loop-Driven Genome Instability. J Mol Biol 2016; 429:3132-3138. [PMID: 27452366 DOI: 10.1016/j.jmb.2016.07.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/05/2016] [Accepted: 07/12/2016] [Indexed: 12/22/2022]
Abstract
DNA repair defects create cancer predisposition in humans by fostering a higher rate of mutations. While DNA repair is quite well characterized, recent studies have identified previously unrecognized relationships between DNA repair and R-loop-mediated genome instability. R-loops are three-stranded nucleic acid structures in which RNA binds to genomic DNA to displace a loop of single-stranded DNA. Mutations in homologous recombination, nucleotide excision repair, crosslink repair, and DNA damage checkpoints have all now been linked to formation and function of transcription-coupled R-loops. This perspective will summarize recent literature linking DNA repair to R-loop-mediated genomic instability and discuss how R-loops may contribute to mutagenesis in DNA-repair-deficient cancers.
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166
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Morales JC, Richard P, Patidar PL, Motea EA, Dang TT, Manley JL, Boothman DA. XRN2 Links Transcription Termination to DNA Damage and Replication Stress. PLoS Genet 2016; 12:e1006107. [PMID: 27437695 PMCID: PMC4954731 DOI: 10.1371/journal.pgen.1006107] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/14/2016] [Indexed: 11/18/2022] Open
Abstract
XRN2 is a 5’-3’ exoribonuclease implicated in transcription termination. Here we demonstrate an unexpected role for XRN2 in the DNA damage response involving resolution of R-loop structures and prevention of DNA double-strand breaks (DSBs). We show that XRN2 undergoes DNA damage-inducible nuclear re-localization, co-localizing with 53BP1 and R loops, in a transcription and R-loop-dependent process. XRN2 loss leads to increased R loops, genomic instability, replication stress, DSBs and hypersensitivity of cells to various DNA damaging agents. We demonstrate that the DSBs that arise with XRN2 loss occur at transcriptional pause sites. XRN2-deficient cells also exhibited an R-loop- and transcription-dependent delay in DSB repair after ionizing radiation, suggesting a novel role for XRN2 in R-loop resolution, suppression of replication stress, and maintenance of genomic stability. Our study highlights the importance of regulating transcription-related activities as a critical component in maintaining genetic stability. Genomic instability is one of the primary causes of disease states, in particular cancer. One major cause of genomic instability is the formation of DNA double strand breaks (DSBs), which are one of the most dangerous types of DNA lesions the cell can encounter. If not repaired in a timely manner, one DSB can lead not only to cell death. If misrepaired, one DSB can lead to a hazardous chromosomal aberration, such as a translocation, that can eventually lead to cancer. The cell encounters and repairs DSBs that arise from naturally occurring cellular processes on a daily basis. A number of studies have demonstrated that aberrant structures that form during transcription under certain circumstances, in particular RNA:DNA hybrids (R loops), can lead to DSB formation and genomic instability, especially during DNA synthesis. Thus, it is important to understand how the cell responds and repairs transcription-mediated DNA damage in general and R loop-related DNA damage in particular. This paper both demonstrates that the XRN transcription termination factor links transcription and DNA damage, but also provides a better understanding of how the cell prevents transcription-related DNA damage.
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Affiliation(s)
- Julio C. Morales
- Department of Neurosurgery, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
- * E-mail: (JCM); (DAB)
| | - Patricia Richard
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Praveen L. Patidar
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Edward A. Motea
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Tuyen T. Dang
- Department of Neurosurgery, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
| | - James L. Manley
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - David A. Boothman
- Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (JCM); (DAB)
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167
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Krishnan S, Petchiappan A, Singh A, Bhatt A, Chatterji D. R-loop induced stress response by second (p)ppGpp synthetase in Mycobacterium smegmatis: functional and domain interdependence. Mol Microbiol 2016; 102:168-82. [PMID: 27349932 DOI: 10.1111/mmi.13453] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2016] [Indexed: 02/03/2023]
Abstract
Persistent R-loops lead to replicative stress due to RNA polymerase stalling and DNA damage. RNase H enzymes facilitate the organisms to survive in the hostile condition by removing these R-loops. MS_RHII-RSD was previously identified to be the second (p)ppGpp synthetase in Mycobacterium smegmatis. The unique presence of an additional RNase HII domain raises an important question regarding the significance of this bifunctional protein. In this report, we demonstrate its ability to hydrolyze R-loops in Escherichia coli exposed to UV stress. MS_RHII-RSD gene expression was upregulated under UV stress, and this gene deleted strain showed increased R-loop accumulation as compared to the wild type. The domains in isolation are known to be inactive, and the full length protein is required for its function. Domain interdependence studies using active site mutants reveal the necessity of a hexamer form with high alpha helical content. In previous studies, bacterial RNase type HI has been mainly implicated in R-loop hydrolysis, but in this study, the RNase HII domain containing protein showed the activity. The prospective of this differential RNase HII activity is discussed. This is the first report to implicate a (p)ppGpp synthetase protein in R-loop-induced stress response.
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Affiliation(s)
- Sushma Krishnan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Anushya Petchiappan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Albel Singh
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B152TT, UK
| | - Apoorva Bhatt
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B152TT, UK
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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168
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Abstract
The recent genomic characterization of cancers has revealed recurrent somatic point mutations and copy number changes affecting genes encoding RNA splicing factors. Initial studies of these 'spliceosomal mutations' suggest that the proteins bearing these mutations exhibit altered splice site and/or exon recognition preferences relative to their wild-type counterparts, resulting in cancer-specific mis-splicing. Such changes in the splicing machinery may create novel vulnerabilities in cancer cells that can be therapeutically exploited using compounds that can influence the splicing process. Further studies to dissect the biochemical, genomic and biological effects of spliceosomal mutations are crucial for the development of cancer therapies targeted at these mutations.
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Affiliation(s)
- Heidi Dvinge
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Eunhee Kim
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Omar Abdel-Wahab
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Leukemia Service, Dept. of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Robert K. Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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169
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Abstract
Organism viability relies on the stable maintenance of specific chromatin landscapes, established during development, that shape cell functions and identities by driving distinct gene expression programs. Yet epigenome maintenance is challenged during transcription, replication, and repair of DNA damage, all of which elicit dynamic changes in chromatin organization. Here, we review recent advances that have shed light on the specialized mechanisms contributing to the restoration of epigenome structure and function after DNA damage in the mammalian cell nucleus. By drawing a parallel with epigenome maintenance during replication, we explore emerging concepts and highlight open issues in this rapidly growing field. In particular, we present our current knowledge of molecular players that support the coordinated maintenance of genome and epigenome integrity in response to DNA damage, and we highlight how nuclear organization impacts genome stability. Finally, we discuss possible functional implications of epigenome plasticity in response to genotoxic stress.
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Affiliation(s)
- Juliette Dabin
- Epigenome Integrity Group, UMR 7216 CNRS, Paris Diderot University, Sorbonne Paris Cité, 75013 Paris Cedex 13, France
| | - Anna Fortuny
- Epigenome Integrity Group, UMR 7216 CNRS, Paris Diderot University, Sorbonne Paris Cité, 75013 Paris Cedex 13, France
| | - Sophie E Polo
- Epigenome Integrity Group, UMR 7216 CNRS, Paris Diderot University, Sorbonne Paris Cité, 75013 Paris Cedex 13, France.
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170
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Affiliation(s)
- Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, Sevilla 41092, Spain; ,
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, Sevilla 41092, Spain; ,
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171
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Brennan-Minnella AM, Arron ST, Chou KM, Cunningham E, Cleaver JE. Sources and consequences of oxidative damage from mitochondria and neurotransmitter signaling. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:322-330. [PMID: 27311994 DOI: 10.1002/em.21995] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 12/13/2015] [Accepted: 12/14/2015] [Indexed: 06/06/2023]
Abstract
Cancer and neurodegeneration represent the extreme responses of growing and terminally differentiated cells to cellular and genomic damage. The damage recognition mechanisms of nucleotide excision repair, epitomized by xeroderma pigmentosum (XP), and Cockayne syndrome (CS), lie at these extremes. Patients with mutations in the DDB2 and XPC damage recognition steps of global genome repair exhibit almost exclusively actinic skin cancer. Patients with mutations in the RNA pol II cofactors CSA and CSB, that regulate transcription coupled repair, exhibit developmental and neurological symptoms, but not cancer. The absence of skin cancer despite increased photosensitivity in CS implies that the DNA repair deficiency is not associated with increased ultraviolet (UV)-induced mutagenesis, unlike DNA repair deficiency in XP that leads to high levels of UV-induced mutagenesis. One attempt to explain the pathology of CS is to attribute genomic damage to endogenously generated reactive oxygen species (ROS). We show that inhibition of complex I of the mitochondria generates increased ROS, above an already elevated level in CSB cells, but without nuclear DNA damage. CSB, but not CSA, quenches ROS liberated from complex I by rotenone. Extracellular signaling by N-methyl-D-aspartic acid in neurons, however, generates ROS enzymatically through oxidase that does lead to oxidative damage to nuclear DNA. The pathology of CS may therefore be caused by impaired oxidative phosphorylation or nuclear damage from neurotransmitters, but without damage-specific mutagenesis. Environ. Mol. Mutagen. 57:322-330, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Angela M Brennan-Minnella
- Department of Neurology, University of California, San Francisco and Veterans Affairs Medical Center, San Francisco, California
| | - Sarah T Arron
- Department of Dermatology, University of California San Francisco, 2340 Sutter Street, San Francisco, California
| | - Kai-Ming Chou
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Room MS 552, Indianapolis, Indiana
| | - Eric Cunningham
- Torrey Pines High School, 3710 Del Mar Heights Road, San Diego, California, 92130
| | - James E Cleaver
- Department of Dermatology, University of California San Francisco, 2340 Sutter Street, San Francisco, California
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172
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Abstract
Examples of associations between human disease and defects in pre-messenger RNA splicing/alternative splicing are accumulating. Although many alterations are caused by mutations in splicing signals or regulatory sequence elements, recent studies have noted the disruptive impact of mutated generic spliceosome components and splicing regulatory proteins. This review highlights recent progress in our understanding of how the altered splicing function of RNA-binding proteins contributes to myelodysplastic syndromes, cancer, and neuropathologies.
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Affiliation(s)
- Benoit Chabot
- Centre of Excellence in RNA Biology, Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Lulzim Shkreta
- Centre of Excellence in RNA Biology, Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
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173
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Giono LE, Nieto Moreno N, Cambindo Botto AE, Dujardin G, Muñoz MJ, Kornblihtt AR. The RNA Response to DNA Damage. J Mol Biol 2016; 428:2636-2651. [PMID: 26979557 DOI: 10.1016/j.jmb.2016.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/01/2016] [Accepted: 03/07/2016] [Indexed: 02/01/2023]
Abstract
Multicellular organisms must ensure genome integrity to prevent accumulation of mutations, cell death, and cancer. The DNA damage response (DDR) is a complex network that senses, signals, and executes multiple programs including DNA repair, cell cycle arrest, senescence, and apoptosis. This entails regulation of a variety of cellular processes: DNA replication and transcription, RNA processing, mRNA translation and turnover, and post-translational modification, degradation, and relocalization of proteins. Accumulated evidence over the past decades has shown that RNAs and RNA metabolism are both regulators and regulated actors of the DDR. This review aims to present a comprehensive overview of the current knowledge on the many interactions between the DNA damage and RNA fields.
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Affiliation(s)
- Luciana E Giono
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Nicolás Nieto Moreno
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Adrián E Cambindo Botto
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Gwendal Dujardin
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Centre for Genomic Regulation, Dr. Aiguader 88, E-08003 Barcelona, Spain
| | - Manuel J Muñoz
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Alberto R Kornblihtt
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET), Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina.
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174
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Kemp MG, Sancar A. ATR Kinase Inhibition Protects Non-cycling Cells from the Lethal Effects of DNA Damage and Transcription Stress. J Biol Chem 2016; 291:9330-42. [PMID: 26940878 DOI: 10.1074/jbc.m116.719740] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Indexed: 01/09/2023] Open
Abstract
ATR (ataxia telangiectasia and Rad-3-related) is a protein kinase that maintains genome stability and halts cell cycle phase transitions in response to DNA lesions that block DNA polymerase movement. These DNA replication-associated features of ATR function have led to the emergence of ATR kinase inhibitors as potential adjuvants for DNA-damaging cancer chemotherapeutics. However, whether ATR affects the genotoxic stress response in non-replicating, non-cycling cells is currently unknown. We therefore used chemical inhibition of ATR kinase activity to examine the role of ATR in quiescent human cells. Although ATR inhibition had no obvious effects on the viability of non-cycling cells, inhibition of ATR partially protected non-replicating cells from the lethal effects of UV and UV mimetics. Analyses of various DNA damage response signaling pathways demonstrated that ATR inhibition reduced the activation of apoptotic signaling by these agents in non-cycling cells. The pro-apoptosis/cell death function of ATR is likely due to transcription stress because the lethal effects of compounds that block RNA polymerase movement were reduced in the presence of an ATR inhibitor. These results therefore suggest that whereas DNA polymerase stalling at DNA lesions activates ATR to protect cell viability and prevent apoptosis, the stalling of RNA polymerases instead activates ATR to induce an apoptotic form of cell death in non-cycling cells. These results have important implications regarding the use of ATR inhibitors in cancer chemotherapy regimens.
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Affiliation(s)
- Michael G Kemp
- From the Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
| | - Aziz Sancar
- From the Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
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175
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Tresini M, Marteijn JA, Vermeulen W. Bidirectional coupling of splicing and ATM signaling in response to transcription-blocking DNA damage. RNA Biol 2016; 13:272-8. [PMID: 26913497 PMCID: PMC4829274 DOI: 10.1080/15476286.2016.1142039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 12/24/2022] Open
Abstract
In response to DNA damage cells activate intricate protein networks to ensure genomic fidelity and tissue homeostasis. DNA damage response signaling pathways coordinate these networks and determine cellular fates, in part, by modulating RNA metabolism. Here we discuss a replication-independent pathway activated by transcription-blocking DNA lesions, which utilizes the ATM signaling kinase to regulate spliceosome function in a reciprocal manner. We present a model according to which, displacement of co-transcriptional spliceosomes from lesion-arrested RNA polymerases, culminates in R-loop formation and non-canonical ATM activation. ATM signals in a feed-forward fashion to further impede spliceosome organization and regulates UV-induced gene expression and alternative splicing genome-wide. This reciprocal coupling between ATM and the spliceosome highlights the importance of ATM signaling in the cellular response to transcription-blocking lesions and supports a key role of the splicing machinery in this process.
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Affiliation(s)
- Maria Tresini
- Department of Genetics, Cancer Genomics Netherlands, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Jurgen A. Marteijn
- Department of Genetics, Cancer Genomics Netherlands, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Wim Vermeulen
- Department of Genetics, Cancer Genomics Netherlands, Erasmus University Medical Center, Rotterdam, The Netherlands
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176
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Abstract
It is emerging that the pathways that process newly transcribed RNA molecules also regulate the response to DNA damage at multiple levels. Here, we discuss recent insights into how RNA processing pathways participate in DNA damage recognition, signaling, and repair, selectively influence the expression of genome-stabilizing proteins, and resolve deleterious DNA/RNA hybrids (R-loops) formed during transcription and RNA processing. The importance of these pathways for the DNA damage response (DDR) is underscored by the growing appreciation that defects in these regulatory connections may be connected to the genome instability involved in several human diseases, including cancer.
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Affiliation(s)
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK.
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177
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Cristini A, Park JH, Capranico G, Legube G, Favre G, Sordet O. DNA-PK triggers histone ubiquitination and signaling in response to DNA double-strand breaks produced during the repair of transcription-blocking topoisomerase I lesions. Nucleic Acids Res 2016; 44:1161-78. [PMID: 26578593 PMCID: PMC4756817 DOI: 10.1093/nar/gkv1196] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/23/2015] [Accepted: 10/26/2015] [Indexed: 12/12/2022] Open
Abstract
Although defective repair of DNA double-strand breaks (DSBs) leads to neurodegenerative diseases, the processes underlying their production and signaling in non-replicating cells are largely unknown. Stabilized topoisomerase I cleavage complexes (Top1cc) by natural compounds or common DNA alterations are transcription-blocking lesions whose repair depends primarily on Top1 proteolysis and excision by tyrosyl-DNA phosphodiesterase-1 (TDP1). We previously reported that stabilized Top1cc produce transcription-dependent DSBs that activate ATM in neurons. Here, we use camptothecin (CPT)-treated serum-starved quiescent cells to induce transcription-blocking Top1cc and show that those DSBs are generated during Top1cc repair from Top1 peptide-linked DNA single-strand breaks generated after Top1 proteolysis and before excision by TDP1. Following DSB induction, ATM activates DNA-PK whose inhibition suppresses H2AX and H2A ubiquitination and the later assembly of activated ATM into nuclear foci. Inhibition of DNA-PK also reduces Top1 ubiquitination and proteolysis as well as resumption of RNA synthesis suggesting that DSB signaling further enhances Top1cc repair. Finally, we show that co-transcriptional DSBs kill quiescent cells. Together, these new findings reveal that DSB production and signaling by transcription-blocking Top1 lesions impact on non-replicating cell fate and provide insights on the molecular pathogenesis of neurodegenerative diseases such as SCAN1 and AT syndromes, which are caused by TDP1 and ATM deficiency, respectively.
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Affiliation(s)
- Agnese Cristini
- Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France
| | - Joon-Hyung Park
- Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France
| | - Giovanni Capranico
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna 40126, Italy
| | - Gaëlle Legube
- Université de Toulouse, UPS, LBCMCP, 31062 Toulouse, France CNRS, LBCMCP, 31062 Toulouse, France
| | - Gilles Favre
- Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France
| | - Olivier Sordet
- Cancer Research Center of Toulouse, INSERM UMR1037, Toulouse 31037, France
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178
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179
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180
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Abstract
The DNA damage response (DDR) has been broadly defined as a complex network of cellular pathways that cooperate to sense and repair lesions in DNA. Multiple types of DNA damage, some natural DNA sequences, nucleotide pool deficiencies and collisions with transcription complexes can cause replication arrest to elicit the DDR. However, in practice, the term DDR as applied to eukaryotic/mammalian cells often refers more specifically to pathways involving the activation of the ATM (ataxia-telangiectasia mutated) and ATR (ATM-Rad3-related) kinases in response to double-strand breaks or arrested replication forks, respectively. Nevertheless, there are distinct responses to particular types of DNA damage that do not involve ATM or ATR. In addition, some of the aberrations that cause replication arrest and elicit the DDR cannot be categorized as direct DNA damage. These include nucleotide pool deficiencies, nucleotide sequences that can adopt non-canonical DNA structures, and collisions between replication forks and transcription complexes. The response to these aberrations can be called the genomic stress response (GSR), a term that is meant to encompass the sensing of all types of DNA aberrations together with the mechanisms involved in coping with them. In addition to fully functional cells, the consequences of processing genomic aberrations may include mutagenesis, genomic rearrangements and lethality.
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Affiliation(s)
- Philip C Hanawalt
- Department of Biology, Stanford University, Stanford, CA 94305-5020, USA.
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181
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Lin L, Swerdel MR, Lazaropoulos MP, Hoffman GS, Toro-Ramos AJ, Wright J, Lederman H, Chen J, Moore JC, Hart RP. Spontaneous ATM Gene Reversion in A-T iPSC to Produce an Isogenic Cell Line. Stem Cell Reports 2015; 5:1097-1108. [PMID: 26677768 PMCID: PMC4682125 DOI: 10.1016/j.stemcr.2015.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 10/16/2015] [Accepted: 10/19/2015] [Indexed: 12/21/2022] Open
Abstract
A spontaneously reverted iPSC line was identified from an A-T subject with heterozygous ATM truncation mutations. The reverted iPSC line expressed ATM protein and was capable of radiation-induced phosphorylation of CHK2 and H2A.X. Genome-wide SNP analysis confirmed a match to source T cells and also to a distinct, non-reverted iPSC line from the same subject. Rearranged T cell receptor sequences predict that the iPSC culture originated as several independently reprogrammed cells that resolved into a single major clone, suggesting that gene correction likely occurred early in the reprogramming process. Gene expression analysis comparing ATM(-/-) iPSC lines to unrelated ATM(+/-) cells identifies a large number of differences, but comparing only the isogenic pair of A-T iPSC lines reveals that the primary pathway affected by loss of ATM is a diminished expression of p53-related mRNAs. Gene reversion in culture, although likely a rare event, provided a novel, reverted cell line for studying ATM function.
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Affiliation(s)
- Lucy Lin
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Mavis R Swerdel
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Michael P Lazaropoulos
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Gary S Hoffman
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Alana J Toro-Ramos
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Jennifer Wright
- A-T Clinic, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Howard Lederman
- A-T Clinic, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jianmin Chen
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA
| | - Jennifer C Moore
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA; Department of Genetics, Rutgers University, Piscataway, NJ 08854, USA; Human Genetics Institute of New Jersey, Piscataway, NJ 08854, USA
| | - Ronald P Hart
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854, USA; Human Genetics Institute of New Jersey, Piscataway, NJ 08854, USA.
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182
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Abstract
ATM and ATR signaling pathways are well conserved throughout evolution and are central to the maintenance of genome integrity. Although the role of both ATM and ATR in DNA repair, cell cycle regulation and apoptosis have been well studied, both still remain in the focus of current research activities owing to their role in cancer. Recent advances in the field suggest that these proteins have an additional function in maintaining cellular homeostasis under both stressed and non-stressed conditions. In this Cell Science at a Glance article and the accompanying poster, we present an overview of recent advances in ATR and ATM research with emphasis on that into the modes of ATM and ATR activation, the different signaling pathways they participate in - including those that do not involve DNA damage - and highlight their relevance in cancer.
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Affiliation(s)
- Poorwa Awasthi
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, M.G. Marg 80, Lucknow 226001, India Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR campus, Lucknow 226001, India
| | - Marco Foiani
- IFOM (Fondazione Istituto FIRC di Oncologia Molecolare), IFOM-IEO Campus Via Adamello 16, Milan 20139, Italy DSBB-Università degli Studi di Milano, Milan 20133, Italy
| | - Amit Kumar
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, M.G. Marg 80, Lucknow 226001, India Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR campus, Lucknow 226001, India
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183
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Shkreta L, Chabot B. The RNA Splicing Response to DNA Damage. Biomolecules 2015; 5:2935-77. [PMID: 26529031 PMCID: PMC4693264 DOI: 10.3390/biom5042935] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 09/20/2015] [Accepted: 10/16/2015] [Indexed: 12/29/2022] Open
Abstract
The number of factors known to participate in the DNA damage response (DDR) has expanded considerably in recent years to include splicing and alternative splicing factors. While the binding of splicing proteins and ribonucleoprotein complexes to nascent transcripts prevents genomic instability by deterring the formation of RNA/DNA duplexes, splicing factors are also recruited to, or removed from, sites of DNA damage. The first steps of the DDR promote the post-translational modification of splicing factors to affect their localization and activity, while more downstream DDR events alter their expression. Although descriptions of molecular mechanisms remain limited, an emerging trend is that DNA damage disrupts the coupling of constitutive and alternative splicing with the transcription of genes involved in DNA repair, cell-cycle control and apoptosis. A better understanding of how changes in splice site selection are integrated into the DDR may provide new avenues to combat cancer and delay aging.
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Affiliation(s)
- Lulzim Shkreta
- Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
| | - Benoit Chabot
- Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
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184
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Lavin MF, Kozlov S, Gatei M, Kijas AW. ATM-Dependent Phosphorylation of All Three Members of the MRN Complex: From Sensor to Adaptor. Biomolecules 2015; 5:2877-902. [PMID: 26512707 PMCID: PMC4693261 DOI: 10.3390/biom5042877] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/14/2015] [Accepted: 10/16/2015] [Indexed: 11/16/2022] Open
Abstract
The recognition, signalling and repair of DNA double strand breaks (DSB) involves the participation of a multitude of proteins and post-translational events that ensure maintenance of genome integrity. Amongst the proteins involved are several which when mutated give rise to genetic disorders characterised by chromosomal abnormalities, cancer predisposition, neurodegeneration and other pathologies. ATM (mutated in ataxia-telangiectasia (A-T) and members of the Mre11/Rad50/Nbs1 (MRN complex) play key roles in this process. The MRN complex rapidly recognises and locates to DNA DSB where it acts to recruit and assist in ATM activation. ATM, in the company of several other DNA damage response proteins, in turn phosphorylates all three members of the MRN complex to initiate downstream signalling. While ATM has hundreds of substrates, members of the MRN complex play a pivotal role in mediating the downstream signalling events that give rise to cell cycle control, DNA repair and ultimately cell survival or apoptosis. Here we focus on the interplay between ATM and the MRN complex in initiating signaling of breaks and more specifically on the adaptor role of the MRN complex in mediating ATM signalling to downstream substrates to control different cellular processes.
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Affiliation(s)
- Martin F Lavin
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia.
| | - Sergei Kozlov
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia.
| | - Magtouf Gatei
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia.
| | - Amanda W Kijas
- UQ Centre for Clinical Research, The University of Queensland, Brisbane, QLD 4029, Australia.
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185
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Schwab RA, Nieminuszczy J, Shah F, Langton J, Lopez Martinez D, Liang CC, Cohn MA, Gibbons RJ, Deans AJ, Niedzwiedz W. The Fanconi Anemia Pathway Maintains Genome Stability by Coordinating Replication and Transcription. Mol Cell 2015; 60:351-61. [PMID: 26593718 PMCID: PMC4644232 DOI: 10.1016/j.molcel.2015.09.012] [Citation(s) in RCA: 249] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 06/20/2015] [Accepted: 09/16/2015] [Indexed: 01/27/2023]
Abstract
DNA replication stress can cause chromosomal instability and tumor progression. One key pathway that counteracts replication stress and promotes faithful DNA replication consists of the Fanconi anemia (FA) proteins. However, how these proteins limit replication stress remains largely elusive. Here we show that conflicts between replication and transcription activate the FA pathway. Inhibition of transcription or enzymatic degradation of transcription-associated R-loops (DNA:RNA hybrids) suppresses replication fork arrest and DNA damage occurring in the absence of a functional FA pathway. Furthermore, we show that simple aldehydes, known to cause leukemia in FA-deficient mice, induce DNA:RNA hybrids in FA-depleted cells. Finally, we demonstrate that the molecular mechanism by which the FA pathway limits R-loop accumulation requires FANCM translocase activity. Failure to activate a response to physiologically occurring DNA:RNA hybrids may critically contribute to the heightened cancer predisposition and bone marrow failure of individuals with mutated FA proteins. Replication and transcription collisions cause genome instability in FA A functional FA pathway protects cells from unscheduled accumulation of R-loops Transcription inhibition or R-loop removal restores normal replication in FA cells FANCM resolves R-loops via its translocase activity
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Affiliation(s)
- Rebekka A Schwab
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Jadwiga Nieminuszczy
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Fenil Shah
- Genome Stability Unit, St. Vincent's Institute, Fitzroy, VIC 3065, Australia
| | - Jamie Langton
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | | | - Chih-Chao Liang
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Martin A Cohn
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Richard J Gibbons
- Medical Research Council Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Andrew J Deans
- Genome Stability Unit, St. Vincent's Institute, Fitzroy, VIC 3065, Australia
| | - Wojciech Niedzwiedz
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK.
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186
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Santos-Pereira JM, Aguilera A. R loops: new modulators of genome dynamics and function. Nat Rev Genet 2015; 16:583-97. [PMID: 26370899 DOI: 10.1038/nrg3961] [Citation(s) in RCA: 517] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
R loops are nucleic acid structures composed of an RNA-DNA hybrid and a displaced single-stranded DNA. Recently, evidence has emerged that R loops occur more often in the genome and have greater physiological relevance, including roles in transcription and chromatin structure, than was previously predicted. Importantly, however, R loops are also a major threat to genome stability. For this reason, several DNA and RNA metabolism factors prevent R-loop formation in cells. Dysfunction of these factors causes R-loop accumulation, which leads to replication stress, genome instability, chromatin alterations or gene silencing, phenomena that are frequently associated with cancer and a number of genetic diseases. We review the current knowledge of the mechanisms controlling R loops and their putative relationship with disease.
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Affiliation(s)
- José M Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Av. Américo Vespucio s/n, Seville 41092, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Av. Américo Vespucio s/n, Seville 41092, Spain
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187
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hPso4/hPrp19: a critical component of DNA repair and DNA damage checkpoint complexes. Oncogene 2015; 35:2279-86. [PMID: 26364595 DOI: 10.1038/onc.2015.321] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/16/2015] [Accepted: 07/19/2015] [Indexed: 12/15/2022]
Abstract
Genome integrity is vital to cellular homeostasis and its forfeiture is linked to deleterious consequences-cancer, immunodeficiency, genetic disorders and premature aging. The human ubiquitin ligase Pso4/Prp19 has emerged as a critical component of multiple DNA damage response (DDR) signaling networks. It not only senses DNA damage, binds double-stranded DNA in a sequence-independent manner, facilitates processing of damaged DNA, promotes DNA end joining, regulates replication protein A (RPA2) phosphorylation and ubiquitination at damaged DNA, but also regulates RNA splicing and mitotic spindle formation in its integral capacity as a scaffold for a multimeric core complex. Accordingly, by virtue of its regulatory and structural interactions with key proteins critical for genome integrity-DNA double-strand break (DSB) repair, DNA interstrand crosslink repair, repair of stalled replication forks and DNA end joining-it fills a unique niche in restoring genomic integrity after multiple types of DNA damage and thus has a vital role in maintaining chromatin integrity and cellular functions. These properties may underlie its ability to thwart replicative senescence and, not surprisingly, have been linked to the self-renewal and colony-forming ability of murine hematopoietic stem cells. This review highlights recent advances in hPso4 research that provides a fascinating glimpse into the pleiotropic activities of a ubiquitously expressed multifunctional E3 ubiquitin ligase.
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188
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Abstract
Environmental agents are constantly challenging cells by damaging DNA, leading to the blockage of transcription elongation. How do cells deal with transcription-blockage and how is transcription restarted after the blocking lesions are removed? Here we review the processes responsible for the removal of transcription-blocking lesions, as well as mechanisms of transcription restart. We also discuss recent data suggesting that blocked RNA polymerases may not resume transcription from the site of the lesion following its removal but, rather, are forced to start over from the beginning of genes.
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189
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DNA damage response: The spliceosome cashes in at the ATM. Nat Rev Mol Cell Biol 2015; 16:454. [PMID: 26153980 DOI: 10.1038/nrm4026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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