201
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Bhatia V, Barroso SI, García-Rubio ML, Tumini E, Herrera-Moyano E, Aguilera A. BRCA2 prevents R-loop accumulation and associates with TREX-2 mRNA export factor PCID2. Nature 2014; 511:362-5. [DOI: 10.1038/nature13374] [Citation(s) in RCA: 359] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 04/08/2014] [Indexed: 12/23/2022]
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202
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Magdalou I, Lopez BS, Pasero P, Lambert SAE. The causes of replication stress and their consequences on genome stability and cell fate. Semin Cell Dev Biol 2014; 30:154-64. [PMID: 24818779 DOI: 10.1016/j.semcdb.2014.04.035] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 04/29/2014] [Indexed: 01/28/2023]
Abstract
Alterations of the dynamics of DNA replication cause genome instability. These alterations known as "replication stress" have emerged as a major source of genomic instability in pre-neoplasic lesions, contributing to cancer development. The concept of replication stress covers a wide variety of events that distort the temporal and spatial DNA replication program. These events have endogenous or exogenous origins and impact globally or locally on the dynamics of DNA replication. They may arise within a short window of time (acute stress) or during each S phase (chronic stress). Here, we review the known situations in which the dynamics of DNA replication is distorted. We have united them in four main categories: (i) inadequate firing of replication origins (deficiency or excess), (ii) obstacles to fork progression, (iii) conflicts between replication and transcription and (iv) DNA replication under inappropriate metabolic conditions (unbalanced DNA replication). Because the DNA replication program is a process tightly regulated by many factors, replication stress often appears as a cascade of events. A local stress may prevent the completion of DNA replication at a single locus and subsequently compromise chromosome segregation in mitosis and therefore have a global effect on genome integrity. Finally, we discuss how replication stress drives genome instability and to what extent it is relevant to cancer biology.
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Affiliation(s)
- Indiana Magdalou
- Université Paris Sud, CNRS, UMR 8200 and Institut de Cancérologie Gustave Roussy, équipe labélisée «LIGUE 2014», Villejuif, France
| | - Bernard S Lopez
- Université Paris Sud, CNRS, UMR 8200 and Institut de Cancérologie Gustave Roussy, équipe labélisée «LIGUE 2014», Villejuif, France
| | - Philippe Pasero
- Institute of Human Genetics, CNRS UPR 1142, équipe labélisée LIGUE contre le Cancer, 141 rue de la Cardonille, 34396 Montpellier, France
| | - Sarah A E Lambert
- Institut Curie, centre de recherche, CNRS UMR338, Bat 110, centre universitaire, 91405 Orsay, France.
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203
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Yang Y, McBride KM, Hensley S, Lu Y, Chedin F, Bedford MT. Arginine methylation facilitates the recruitment of TOP3B to chromatin to prevent R loop accumulation. Mol Cell 2014; 53:484-97. [PMID: 24507716 DOI: 10.1016/j.molcel.2014.01.011] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 12/09/2013] [Accepted: 01/03/2014] [Indexed: 10/25/2022]
Abstract
Tudor domain-containing protein 3 (TDRD3) is a major methylarginine effector molecule that reads methyl-histone marks and facilitates gene transcription. However, the underlying mechanism by which TDRD3 functions as a transcriptional coactivator is unknown. We identified topoisomerase IIIB (TOP3B) as a component of the TDRD3 complex. TDRD3 serves as a molecular bridge between TOP3B and arginine-methylated histones. The TDRD3-TOP3B complex is recruited to the c-MYC gene promoter primarily by the H4R3me2a mark, and the complex promotes c-MYC gene expression. TOP3B relaxes negative supercoiled DNA and reduces transcription-generated R loops in vitro. TDRD3 knockdown in cells increases R loop formation at the c-MYC locus, and Tdrd3 null mice exhibit elevated R loop formation at this locus in B cells. Tdrd3 null mice show significantly increased c-Myc/Igh translocation, a process driven by R loop structures. By reducing negative supercoiling and resolving R loops, TOP3B promotes transcription, protects against DNA damage, and reduces the frequency of chromosomal translocations.
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Affiliation(s)
- Yanzhong Yang
- The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA
| | - Kevin M McBride
- The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA
| | - Sean Hensley
- The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA
| | - Yue Lu
- The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA
| | - Frederic Chedin
- Department of Molecular & Cellular Biology, The University of California at Davis, Davis, CA 95616, USA
| | - Mark T Bedford
- The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA.
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204
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Mechanisms of genome instability induced by RNA-processing defects. Trends Genet 2014; 30:245-53. [PMID: 24794811 DOI: 10.1016/j.tig.2014.03.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/25/2014] [Accepted: 03/26/2014] [Indexed: 12/20/2022]
Abstract
The role of normal transcription and RNA processing in maintaining genome integrity is becoming increasingly appreciated in organisms ranging from bacteria to humans. Several mutations in RNA biogenesis factors have been implicated in human cancers, but the mechanisms and potential connections to tumor genome instability are not clear. Here, we discuss how RNA-processing defects could destabilize genomes through mutagenic R-loop structures and by altering expression of genes required for genome stability. A compelling body of evidence now suggests that researchers should be directly testing these mechanisms in models of human cancer.
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205
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Loomis EW, Sanz LA, Chédin F, Hagerman PJ. Transcription-associated R-loop formation across the human FMR1 CGG-repeat region. PLoS Genet 2014; 10:e1004294. [PMID: 24743386 PMCID: PMC3990486 DOI: 10.1371/journal.pgen.1004294] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 02/21/2014] [Indexed: 11/24/2022] Open
Abstract
Expansion of a trinucleotide (CGG) repeat element within the 5′ untranslated region (5′UTR) of the human FMR1 gene is responsible for a number of heritable disorders operating through distinct pathogenic mechanisms: gene silencing for fragile X syndrome (>200 CGG) and RNA toxic gain-of-function for FXTAS (∼55–200 CGG). Existing models have focused almost exclusively on post-transcriptional mechanisms, but co-transcriptional processes could also contribute to the molecular dysfunction of FMR1. We have observed that transcription through the GC-rich FMR1 5′UTR region favors R-loop formation, with the nascent (G-rich) RNA forming a stable RNA:DNA hybrid with the template DNA strand, thereby displacing the non-template DNA strand. Using DNA:RNA (hybrid) immunoprecipitation (DRIP) of genomic DNA from cultured human dermal fibroblasts with both normal (∼30 CGG repeats) and premutation (55<CGG<200 repeats) alleles, we provide evidence for FMR1 R-loop formation in human genomic DNA. Using a doxycycline (DOX)-inducible episomal system in which both the CGG-repeat and transcription frequency can be varied, we further show that R-loop formation increases with higher expression levels. Finally, non-denaturing bisulfite mapping of the displaced single-stranded DNA confirmed R-loop formation at the endogenous FMR1 locus and further indicated that R-loops formed over CGG repeats may be prone to structural complexities, including hairpin formation, not commonly associated with other R-loops. These observations introduce a new molecular feature of the FMR1 gene that is directly affected by CGG-repeat expansion and is likely to be involved in the associated cellular dysfunction. Expansion of a CGG-repeat element within the human FMR1 gene is responsible for multiple human diseases, including fragile X syndrome and fragile X-associated tremor/ataxia syndrome (FXTAS). These diseases occur in separate ranges of repeat length and are characterized by profoundly different molecular mechanisms. Fragile X syndrome results from FMR1 gene silencing, whereas FXTAS is associated with an increase in transcription and toxicity of the CGG-repeat-containing mRNA. This study introduces a previously unknown molecular feature of the FMR1 locus, namely the co-transcriptional formation of three-stranded R-loop structures upon re-annealing of the nascent FMR1 transcript to the template DNA strand. R-loops are involved in the normal function of human CpG island promoters in that they contribute to protecting these sequences from DNA methylation. However, excessive R-loop formation can lead to activation of the DNA damage response and result in genomic instability. We used antibody recognition and chemical single-stranded DNA footprinting to show that R-loops form at the FMR1 locus with increasing frequency and greater structural complexity as the CGG-repeat length increases. This discovery provides a missing piece of both the complex FMR1 molecular puzzle and the diseases resulting from CGG-repeat expansion.
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Affiliation(s)
- Erick W. Loomis
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - Lionel A. Sanz
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, United States of America
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, United States of America
- The Genome Center, University of California, Davis, Davis, California, United States of America
| | - Paul J. Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
- MIND Institute, University of California, Davis, Health System, Sacramento, California, United States of America
- * E-mail:
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206
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Chan YA, Aristizabal MJ, Lu PYT, Luo Z, Hamza A, Kobor MS, Stirling PC, Hieter P. Genome-wide profiling of yeast DNA:RNA hybrid prone sites with DRIP-chip. PLoS Genet 2014; 10:e1004288. [PMID: 24743342 PMCID: PMC3990523 DOI: 10.1371/journal.pgen.1004288] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 02/21/2014] [Indexed: 12/17/2022] Open
Abstract
DNA:RNA hybrid formation is emerging as a significant cause of genome instability in biological systems ranging from bacteria to mammals. Here we describe the genome-wide distribution of DNA:RNA hybrid prone loci in Saccharomyces cerevisiae by DNA:RNA immunoprecipitation (DRIP) followed by hybridization on tiling microarray. These profiles show that DNA:RNA hybrids preferentially accumulated at rDNA, Ty1 and Ty2 transposons, telomeric repeat regions and a subset of open reading frames (ORFs). The latter are generally highly transcribed and have high GC content. Interestingly, significant DNA:RNA hybrid enrichment was also detected at genes associated with antisense transcripts. The expression of antisense-associated genes was also significantly altered upon overexpression of RNase H, which degrades the RNA in hybrids. Finally, we uncover mutant-specific differences in the DRIP profiles of a Sen1 helicase mutant, RNase H deletion mutant and Hpr1 THO complex mutant compared to wild type, suggesting different roles for these proteins in DNA:RNA hybrid biology. Our profiles of DNA:RNA hybrid prone loci provide a resource for understanding the properties of hybrid-forming regions in vivo, extend our knowledge of hybrid-mitigating enzymes, and contribute to models of antisense-mediated gene regulation. A summary of this paper was presented at the 26th International Conference on Yeast Genetics and Molecular Biology, August 2013.
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Affiliation(s)
- Yujia A. Chan
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - Maria J. Aristizabal
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, Canada
| | - Phoebe Y. T. Lu
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, Canada
| | - Zongli Luo
- Wine Research Centre, University of British Columbia, Vancouver, Canada
| | - Akil Hamza
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - Michael S. Kobor
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Peter C. Stirling
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
- * E-mail: (PCS); (PH)
| | - Philip Hieter
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- * E-mail: (PCS); (PH)
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207
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Myc induced replicative stress response: How to cope with it and exploit it. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:517-24. [PMID: 24735945 DOI: 10.1016/j.bbagrm.2014.04.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 04/07/2014] [Accepted: 04/08/2014] [Indexed: 11/21/2022]
Abstract
Myc is a cellular oncogene frequently deregulated in cancer that has the ability to stimulate cellular growth by promoting a number of proliferative and pro-survival pathways. Here we will focus on how Myc controls a number of diverse cellular processes that converge to ensure processivity and robustness of DNA synthesis, thus preventing the inherent replicative stress responses usually evoked by oncogenic lesions. While these processes provide cancer cells with a long-term proliferative advantage, they also represent cancer liabilities that can be exploited to devise innovative therapeutic approaches to target Myc overexpressing tumors. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.
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208
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Quality control of mRNP biogenesis: networking at the transcription site. Semin Cell Dev Biol 2014; 32:37-46. [PMID: 24713468 DOI: 10.1016/j.semcdb.2014.03.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 03/28/2014] [Indexed: 11/20/2022]
Abstract
Eukaryotic cells carry out quality control (QC) over the processes of RNA biogenesis to inactivate or eliminate defective transcripts, and to avoid their production. In the case of protein-coding transcripts, the quality controls can sense defects in the assembly of mRNA-protein complexes, in the processing of the precursor mRNAs, and in the sequence of open reading frames. Different types of defect are monitored by different specialized mechanisms. Some of them involve dedicated factors whose function is to identify faulty molecules and target them for degradation. Others are the result of a more subtle balance in the kinetics of opposing activities in the mRNA biogenesis pathway. One way or another, all such mechanisms hinder the expression of the defective mRNAs through processes as diverse as rapid degradation, nuclear retention and transcriptional silencing. Three major degradation systems are responsible for the destruction of the defective transcripts: the exosome, the 5'-3' exoribonucleases, and the nonsense-mediated mRNA decay (NMD) machinery. This review summarizes recent findings on the cotranscriptional quality control of mRNA biogenesis, and speculates that a protein-protein interaction network integrates multiple mRNA degradation systems with the transcription machinery.
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209
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Santos-Pereira JM, Herrero AB, Moreno S, Aguilera A. Npl3, a new link between RNA-binding proteins and the maintenance of genome integrity. Cell Cycle 2014; 13:1524-9. [PMID: 24694687 DOI: 10.4161/cc.28708] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The mRNA is co-transcriptionally bound by a number of RNA-binding proteins (RBPs) that contribute to its processing and formation of an export-competent messenger ribonucleoprotein particle (mRNP). In the last few years, increasing evidence suggests that RBPs play a key role in preventing transcription-associated genome instability. Part of this instability is mediated by the accumulation of co-transcriptional R loops, which may impair replication fork (RF) progression due to collisions between transcription and replication machineries. In addition, some RBPs have been implicated in DNA repair and/or the DNA damage response (DDR). Recently, the Npl3 protein, one of the most abundant heterogeneous nuclear ribonucleoproteins (hnRNPs) in yeast, has been shown to prevent transcription-associated genome instability and accumulation of RF obstacles, partially associated with R-loop formation. Interestingly, Npl3 seems to have additional functions in DNA repair, and npl3∆ mutants are highly sensitive to genotoxic agents, such as the antitumor drug trabectedin. Here we discuss the role of Npl3 in particular, and RBPs in general, in the connection of transcription with replication and genome instability, and its effect on the DDR.
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Affiliation(s)
- José M Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER; Universidad de Sevilla-CSIC; Seville, Spain
| | - Ana B Herrero
- Instituto de Biología Molecular y Celular del Cáncer; Universidad de Salamanca-CSIC; Salamanca, Spain
| | - Sergio Moreno
- Instituto de Biología Funcional y Genómica; Universidad de Salamanca-CSIC; Salamanca, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER; Universidad de Sevilla-CSIC; Seville, Spain
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210
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The yeast and human FACT chromatin-reorganizing complexes solve R-loop-mediated transcription-replication conflicts. Genes Dev 2014; 28:735-48. [PMID: 24636987 PMCID: PMC4015491 DOI: 10.1101/gad.234070.113] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The chromatin-reorganizing complex FACT functions in transcription elongation and DNA replication, yet its role in replication is not well understood. Here, Herrera-Moyano et al. find increased recombination rates and genetic instability in yeast mutants and FACT-depleted human cells. The results demonstrate a conserved function for FACT in the resolution of transcription–replication conflicts mediated by R loops. This study therefore links the roles of FACT in transcription elongation and DNA replication. FACT (facilitates chromatin transcription) is a chromatin-reorganizing complex that swaps nucleosomes around the RNA polymerase during transcription elongation and has a role in replication that is not fully understood yet. Here we show that recombination factors are required for the survival of yeast FACT mutants, consistent with an accumulation of DNA breaks that we detected by Rad52 foci and transcription-dependent hyperrecombination. Breaks also accumulate in FACT-depleted human cells, as shown by γH2AX foci and single-cell electrophoresis. Furthermore, FACT-deficient yeast and human cells show replication impairment, which in yeast we demonstrate by ChIP–chip (chromatin immunoprecipitation [ChIP] coupled with microarray analysis) of Rrm3 to occur genome-wide but preferentially at highly transcribed regions. Strikingly, in yeast FACT mutants, high levels of Rad52 foci are suppressed by RNH1 overexpression; R loops accumulate at high levels, and replication becomes normal when global RNA synthesis is inhibited in FACT-depleted human cells. The results demonstrate a key function of FACT in the resolution of R-loop-mediated transcription–replication conflicts, likely associated with a specific chromatin organization.
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211
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Yeo AJ, Becherel OJ, Luff JE, Cullen JK, Wongsurawat T, Jenjaroenpoon P, Kuznetsov VA, McKinnon PJ, Lavin MF. R-loops in proliferating cells but not in the brain: implications for AOA2 and other autosomal recessive ataxias. PLoS One 2014; 9:e90219. [PMID: 24637776 PMCID: PMC3956458 DOI: 10.1371/journal.pone.0090219] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/27/2014] [Indexed: 11/18/2022] Open
Abstract
Disruption of the Setx gene, defective in ataxia oculomotor apraxia type 2 (AOA2) leads to the accumulation of DNA/RNA hybrids (R-loops), failure of meiotic recombination and infertility in mice. We report here the presence of R-loops in the testes from other autosomal recessive ataxia mouse models, which correlate with fertility in these disorders. R-loops were coincident in cells showing high basal levels of DNA double strand breaks and in those cells undergoing apoptosis. Depletion of Setx led to high basal levels of R-loops and these were enhanced further by DNA damage both in vitro and in vivo in tissues with proliferating cells. There was no evidence for accumulation of R-loops in the brains of mice where Setx, Atm, Tdp1 or Aptx genes were disrupted. These data provide further evidence for genome destabilization as a consequence of disrupted transcription in the presence of DNA double strand breaks arising during DNA replication or recombination. They also suggest that R-loop accumulation does not contribute to the neurodegenerative phenotype in these autosomal recessive ataxias.
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Affiliation(s)
- Abrey J. Yeo
- QIMR Berghofer Medical Research Institute, Radiation Biology and Oncology Laboratory, Brisbane, Queensland, Australia
- School of Medicine, University of Queensland, Herston, Queensland, Australia
| | - Olivier J. Becherel
- QIMR Berghofer Medical Research Institute, Radiation Biology and Oncology Laboratory, Brisbane, Queensland, Australia
- School of Chemistry and Molecular Biology, University of Queensland, St. Lucia, Queensland, Australia
| | - John E. Luff
- QIMR Berghofer Medical Research Institute, Radiation Biology and Oncology Laboratory, Brisbane, Queensland, Australia
| | - Jason K. Cullen
- QIMR Berghofer Medical Research Institute, Radiation Biology and Oncology Laboratory, Brisbane, Queensland, Australia
| | - Thidathip Wongsurawat
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Singapore, Singapore
- School of Computer Engineering, Nanyang Technological University, Singapore, Singapore
| | - Piroon Jenjaroenpoon
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Singapore, Singapore
| | - Vladimir A. Kuznetsov
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, Singapore, Singapore
- School of Computer Engineering, Nanyang Technological University, Singapore, Singapore
| | - Peter J. McKinnon
- Department of Genetics and Tumour Cell Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Martin F. Lavin
- QIMR Berghofer Medical Research Institute, Radiation Biology and Oncology Laboratory, Brisbane, Queensland, Australia
- School of Medicine, University of Queensland, Herston, Queensland, Australia
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212
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Gaillard H, Aguilera A. Cleavage factor I links transcription termination to DNA damage response and genome integrity maintenance in Saccharomyces cerevisiae. PLoS Genet 2014; 10:e1004203. [PMID: 24603480 PMCID: PMC3945788 DOI: 10.1371/journal.pgen.1004203] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 01/10/2014] [Indexed: 12/18/2022] Open
Abstract
During transcription, the nascent pre-mRNA undergoes a series of processing steps before being exported to the cytoplasm. The 3'-end processing machinery involves different proteins, this function being crucial to cell growth and viability in eukaryotes. Here, we found that the rna14-1, rna15-1, and hrp1-5 alleles of the cleavage factor I (CFI) cause sensitivity to UV-light in the absence of global genome repair in Saccharomyces cerevisiae. Unexpectedly, CFI mutants were proficient in UV-lesion repair in a transcribed gene. DNA damage checkpoint activation and RNA polymerase II (RNAPII) degradation in response to UV were delayed in CFI-deficient cells, indicating that CFI participates in the DNA damage response (DDR). This is further sustained by the synthetic growth defects observed between rna14-1 and mutants of different repair pathways. Additionally, we found that rna14-1 suffers severe replication progression defects and that a functional G1/S checkpoint becomes essential in avoiding genetic instability in those cells. Thus, CFI function is required to maintain genome integrity and to prevent replication hindrance. These findings reveal a new function for CFI in the DDR and underscore the importance of coordinating transcription termination with replication in the maintenance of genomic stability.
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Affiliation(s)
- Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Sevilla, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC, Sevilla, Spain
- * E-mail:
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213
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Wang IX, Core LJ, Kwak H, Brady L, Bruzel A, McDaniel L, Richards AL, Wu M, Grunseich C, Lis JT, Cheung VG. RNA-DNA differences are generated in human cells within seconds after RNA exits polymerase II. Cell Rep 2014; 6:906-15. [PMID: 24561252 DOI: 10.1016/j.celrep.2014.01.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 12/27/2013] [Accepted: 01/28/2014] [Indexed: 10/25/2022] Open
Abstract
RNA sequences are expected to be identical to their corresponding DNA sequences. Here, we found all 12 types of RNA-DNA sequence differences (RDDs) in nascent RNA. Our results show that RDDs begin to occur in RNA chains ~55 nt from the RNA polymerase II (Pol II) active site. These RDDs occur so soon after transcription that they are incompatible with known deaminase-mediated RNA-editing mechanisms. Moreover, the 55 nt delay in appearance indicates that they do not arise during RNA synthesis by Pol II or as a direct consequence of modified base incorporation. Preliminary data suggest that RDD and R-loop formations may be coupled. These findings identify sequence substitution as an early step in cotranscriptional RNA processing.
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Affiliation(s)
- Isabel X Wang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Leighton J Core
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Hojoong Kwak
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Lauren Brady
- Cell and Molecular Biology Graduate Program, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alan Bruzel
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Lee McDaniel
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Allison L Richards
- Human Genetics Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ming Wu
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Christopher Grunseich
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
| | - Vivian G Cheung
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA; Departments of Pediatrics and Genetics, University of Michigan, Ann Arbor, MI 48109, USA.
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214
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Richard P, Manley JL. SETX sumoylation: A link between DNA damage and RNA surveillance disrupted in AOA2. Rare Dis 2014; 2:e27744. [PMID: 25054092 PMCID: PMC4091563 DOI: 10.4161/rdis.27744] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 12/18/2013] [Accepted: 01/06/2014] [Indexed: 01/09/2023] Open
Abstract
Senataxin (SETX) is a putative RNA:DNA helicase that is mutated in two distinct juvenile neurological disorders, AOA2 and ALS4. SETX is involved in the response to oxidative stress and is suggested to resolve R loops formed at transcription termination sites or at sites of collisions between the transcription and replication machineries. R loops are hybrids between RNA and DNA that are believed to lead to DNA damage and genomic instability. We discovered that Rrp45, a core component of the exosome, is a SETX-interacting protein and that the interaction depends on modification of SETX by sumoylation. Importantly, we showed that AOA2 but not ALS4 mutations prevented both SETX sumoylation and the Rrp45 interaction. We also found that upon replication stress induction, SETX and Rrp45 co-localize in nuclear foci that constitute sites of R-loop formation generated by transcription and replication machinery collisions. We suggest that SETX links transcription, DNA damage and RNA surveillance, and discuss here how this link can be relevant to AOA2 disease.
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Affiliation(s)
- Patricia Richard
- Department of Biological Sciences; Columbia University; New York, NY USA
| | - James L Manley
- Department of Biological Sciences; Columbia University; New York, NY USA
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215
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Santos-Pereira JM, Herrero AB, García-Rubio ML, Marín A, Moreno S, Aguilera A. The Npl3 hnRNP prevents R-loop-mediated transcription-replication conflicts and genome instability. Genes Dev 2013; 27:2445-58. [PMID: 24240235 PMCID: PMC3841734 DOI: 10.1101/gad.229880.113] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/11/2013] [Indexed: 12/18/2022]
Abstract
Transcription is a major obstacle for replication fork (RF) progression and a cause of genome instability. Part of this instability is mediated by cotranscriptional R loops, which are believed to increase by suboptimal assembly of the nascent messenger ribonucleoprotein particle (mRNP). However, no clear evidence exists that heterogeneous nuclear RNPs (hnRNPs), the basic mRNP components, prevent R-loop stabilization. Here we show that yeast Npl3, the most abundant RNA-binding hnRNP, prevents R-loop-mediated genome instability. npl3Δ cells show transcription-dependent and R-loop-dependent hyperrecombination and genome-wide replication obstacles as determined by accumulation of the Rrm3 helicase. Such obstacles preferentially occur at long and highly expressed genes, to which Npl3 is preferentially bound in wild-type cells, and are reduced by RNase H1 overexpression. The resulting replication stress confers hypersensitivity to double-strand break-inducing agents. Therefore, our work demonstrates that mRNP factors are critical for genome integrity and opens the option of using them as therapeutic targets in anti-cancer treatment.
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Affiliation(s)
- José M. Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas (CSIC), 41092 Seville, Spain
| | - Ana B. Herrero
- Instituto de Biología Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, 37008 Salamanca, Spain
| | - María L. García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Antonio Marín
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Sergio Moreno
- Instituto de Biología Molecular y Celular del Cáncer, CSIC-Universidad de Salamanca, 37008 Salamanca, Spain
- Instituto de Biología Funcional y Genómica, CSIC-Universidad de Salamanca, 37007 Salamanca, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
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216
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Corden JL. RNA polymerase II C-terminal domain: Tethering transcription to transcript and template. Chem Rev 2013; 113:8423-55. [PMID: 24040939 PMCID: PMC3988834 DOI: 10.1021/cr400158h] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jeffry L Corden
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore Maryland 21205, United States
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217
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Bennett CL, Chen Y, Vignali M, Lo RS, Mason AG, Unal A, Huq Saifee NP, Fields S, La Spada AR. Protein interaction analysis of senataxin and the ALS4 L389S mutant yields insights into senataxin post-translational modification and uncovers mutant-specific binding with a brain cytoplasmic RNA-encoded peptide. PLoS One 2013; 8:e78837. [PMID: 24244371 PMCID: PMC3823977 DOI: 10.1371/journal.pone.0078837] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 09/24/2013] [Indexed: 12/12/2022] Open
Abstract
Senataxin is a large 303 kDa protein linked to neuron survival, as recessive mutations cause Ataxia with Oculomotor Apraxia type 2 (AOA2), and dominant mutations cause amyotrophic lateral sclerosis type 4 (ALS4). Senataxin contains an amino-terminal protein-interaction domain and a carboxy-terminal DNA/RNA helicase domain. In this study, we focused upon the common ALS4 mutation, L389S, by performing yeast two-hybrid screens of a human brain expression library with control senataxin or L389S senataxin as bait. Interacting clones identified from the two screens were collated, and redundant hits and false positives subtracted to yield a set of 13 protein interactors. Among these hits, we discovered a highly specific and reproducible interaction of L389S senataxin with a peptide encoded by the antisense sequence of a brain-specific non-coding RNA, known as BCYRN1. We further found that L389S senataxin interacts with other proteins containing regions of conserved homology with the BCYRN1 reverse complement-encoded peptide, suggesting that such aberrant protein interactions may contribute to L389S ALS4 disease pathogenesis. As the yeast two-hybrid screen also demonstrated senataxin self-association, we confirmed senataxin dimerization via its amino-terminal binding domain and determined that the L389S mutation does not abrogate senataxin self-association. Finally, based upon detection of interactions between senataxin and ubiquitin-SUMO pathway modification enzymes, we examined senataxin for the presence of ubiquitin and SUMO monomers, and observed this post-translational modification. Our senataxin protein interaction study reveals a number of features of senataxin biology that shed light on senataxin normal function and likely on senataxin molecular pathology in ALS4.
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Affiliation(s)
- Craig L. Bennett
- Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Queensland, Australia
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Yingzhang Chen
- Department of Pediatrics, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Marissa Vignali
- Department of Genome Sciences, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Russell S. Lo
- Department of Genome Sciences, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Amanda G. Mason
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Asli Unal
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
| | - Nabiha P. Huq Saifee
- Department of Pharmacology, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Stanley Fields
- Department of Genome Sciences, University of Washington Medical Center, Seattle, Washington, United States of America
| | - Albert R. La Spada
- Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America
- Department of Cellular & Molecular Medicine, University of California San Diego, La Jolla, California, United States of America
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
- Rady Children’s Hospital, La Jolla, California, United States of America
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218
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Abstract
Transcription is apparently risky business. Its intrinsic mutagenic potential must be kept in check by networks of DNA repair factors that monitor the transcription process to repair DNA lesions that could otherwise compromise transcriptional fidelity and genome integrity. Intriguingly, recent studies point to an even more direct function of DNA repair complexes as coactivators of transcription and the unexpected role of "scheduled" DNA damage/repair at gene promoters. Paradoxically, spontaneous DNA double-strand breaks also induce ectopic transcription that is essential for repair. Thus, transcription, DNA damage, and repair may be more physically and functionally intertwined than previously appreciated.
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Affiliation(s)
- Yick W. Fong
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Claudia Cattoglio
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Robert Tjian
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, CA 94720, USA
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219
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R loops are linked to histone H3 S10 phosphorylation and chromatin condensation. Mol Cell 2013; 52:583-90. [PMID: 24211264 DOI: 10.1016/j.molcel.2013.10.006] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/04/2013] [Accepted: 10/01/2013] [Indexed: 12/20/2022]
Abstract
R loops are transcription byproducts that constitute a threat to genome integrity. Here we show that R loops are tightly linked to histone H3 S10 phosphorylation (H3S10P), a mark of chromatin condensation. Chromatin immunoprecipitation (ChIP)-on-chip (ChIP-chip) analyses reveal H3S10P accumulation at centromeres, pericentromeric chromatin, and a large number of active open reading frames (ORFs) in R-loop-accumulating yeast cells, better observed in G1. Histone H3S10 plays a key role in maintaining genome stability, as scored by ectopic recombination and plasmid loss, Rad52 foci, and Rad53 checkpoint activation. H3S10P coincides with the presence of DNA-RNA hybrids, is suppressed by ribonuclease H overexpression, and causes reduced accessibility of restriction endonucleases, implying a tight connection between R loops, H3S10P, and chromatin compaction. Such histone modifications were also observed in R-loop-accumulating Caenorhabditis elegans and HeLa cells. We therefore provide a role of RNA in chromatin structure essential to understand how R loops modulate genome dynamics.
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220
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Gwynn EJ, Smith AJ, Guy CP, Savery NJ, McGlynn P, Dillingham MS. The conserved C-terminus of the PcrA/UvrD helicase interacts directly with RNA polymerase. PLoS One 2013; 8:e78141. [PMID: 24147116 PMCID: PMC3797733 DOI: 10.1371/journal.pone.0078141] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 09/13/2013] [Indexed: 12/31/2022] Open
Abstract
UvrD-like helicases play diverse roles in DNA replication, repair and recombination pathways. An emerging body of evidence suggests that their different cellular functions are directed by interactions with partner proteins that target unwinding activity to appropriate substrates. Recent studies in E. coli have shown that UvrD can act as an accessory replicative helicase that resolves conflicts between the replisome and transcription complexes, but the mechanism is not understood. Here we show that the UvrD homologue PcrA interacts physically with B. subtilis RNA polymerase, and that an equivalent interaction is conserved in E. coli where UvrD, but not the closely related helicase Rep, also interacts with RNA polymerase. The PcrA-RNAP interaction is direct and independent of nucleic acids or additional mediator proteins. A disordered but highly conserved C-terminal region of PcrA, which distinguishes PcrA/UvrD from otherwise related enzymes such as Rep, is both necessary and sufficient for interaction with RNA polymerase.
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Affiliation(s)
- Emma J. Gwynn
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Abigail J. Smith
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Colin P. Guy
- School of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Nigel J. Savery
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Peter McGlynn
- School of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Department of Biology, University of York, York, United Kingdom
| | - Mark S. Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, United Kingdom
- * E-mail:
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221
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Richard P, Feng S, Manley JL. A SUMO-dependent interaction between Senataxin and the exosome, disrupted in the neurodegenerative disease AOA2, targets the exosome to sites of transcription-induced DNA damage. Genes Dev 2013; 27:2227-32. [PMID: 24105744 PMCID: PMC3814643 DOI: 10.1101/gad.224923.113] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Senataxin (SETX) is an RNA/DNA helicase implicated in transcription termination and the DNA damage response and is mutated in two distinct neurological disorders: AOA2 (ataxia oculomotor apraxia 2) and ALS4 (amyotrophic lateral sclerosis 4). Here we provide evidence that Rrp45, a subunit of the exosome, associates with SETX in a manner dependent on SETX sumoylation. We show that the interaction and SETX sumoylation are disrupted by SETX mutations associated with AOA2 but not ALS4. Furthermore, Rrp45 colocalizes with SETX in distinct foci upon induction of transcription-related DNA damage. Our results thus provide evidence for a SUMO-dependent interaction between SETX and the exosome, disrupted in AOA2, that targets the exosome to sites of DNA damage.
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Affiliation(s)
- Patricia Richard
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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222
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Pfeiffer V, Crittin J, Grolimund L, Lingner J. The THO complex component Thp2 counteracts telomeric R-loops and telomere shortening. EMBO J 2013; 32:2861-71. [PMID: 24084588 DOI: 10.1038/emboj.2013.217] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 09/10/2013] [Indexed: 12/13/2022] Open
Abstract
Telomere maintenance by the conventional DNA replication machinery and telomerase is assisted by specialized DNA helicases, nucleases and telomere binding proteins. Here, we identify the THO components at telomeres and define critical roles of this complex in telomere stability. Deletion of the THO-subunit THP2 leads to telomere shortening. We discover that telomeres contain RNA:DNA hybrid structures or R-loops which involve the long-noncoding RNA TERRA and which accumulate in thp2-Δ cells. Telomere length is not restored by R-loop removal upon RNase H overexpression, but by deletion of Exonuclease 1 (Exo1). Replication stress further enhances the short telomere phenotype of THP2 mutants. Similar events occur upon induced transcription of TERRA and genetic analysis links Thp2 to TERRA function. Altogether, our data indicate that THO, through the interplay with TERRA, regulates chromosome end processing activities and prevents interference with semiconservative DNA replication of telomeric DNA.
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Affiliation(s)
- Verena Pfeiffer
- EPFL-Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, ISREC-Swiss Institute for Experimental Cancer Research, Lausanne, Switzerland
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223
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Abstract
Genomes are transmitted faithfully from dividing cells to their offspring. Changes that occur during DNA repair, chromosome duplication, and transmission or via recombination provide a natural source of genetic variation. They occur at low frequency because of the intrinsic variable nature of genomes, which we refer to as genome instability. However, genome instability can be enhanced by exposure to external genotoxic agents or as the result of cellular pathologies. We review the causes of genome instability as well as how it results in hyper-recombination, genome rearrangements, and chromosome fragmentation and loss, which are mainly mediated by double-strand breaks or single-strand gaps. Such events are primarily associated with defects in DNA replication and the DNA damage response, and show high incidence at repetitive DNA, non-B DNA structures, DNA-protein barriers, and highly transcribed regions. Identifying the causes of genome instability is crucial to understanding genome dynamics during cell proliferation and its role in cancer, aging, and a number of rare genetic diseases.
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Affiliation(s)
- Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, 41092 Seville, Spain;
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224
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D’Heygère F, Rabhi M, Boudvillain M. Phyletic distribution and conservation of the bacterial transcription termination factor Rho. Microbiology (Reading) 2013; 159:1423-1436. [DOI: 10.1099/mic.0.067462-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- François D’Heygère
- Ecole doctorale Santé, Sciences Biologiques et Chimie du Vivant (ED 549), Université d’Orléans, France
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Makhlouf Rabhi
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Marc Boudvillain
- ITP Sciences Biologiques et Chimie du Vivant, Université d’Orléans, France
- Centre de Biophysique Moléculaire, CNRS UPR4301, rue Charles Sadron, 45071 Orléans cedex 2, France
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225
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Transcription-replication encounters, consequences and genomic instability. Nat Struct Mol Biol 2013; 20:412-8. [PMID: 23552296 DOI: 10.1038/nsmb.2543] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/07/2013] [Indexed: 12/16/2022]
Abstract
To ensure accurate duplication of genetic material, the replication fork must overcome numerous natural obstacles on its way, including transcription complexes engaged along the same template. Here we review the various levels of interdependence between transcription and replication processes and how different types of encounters between RNA- and DNA-polymerase complexes may result in clashes of those machineries on the DNA template and thus increase genomic instability. In addition, we summarize strategies evolved in bacteria and eukaryotes to minimize the consequences of collisions, including R-loop formation and topological stresses.
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226
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Abstract
A protein long recognized for its role in DNA repair has now paradoxically been implicated in DNA damage.
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Affiliation(s)
- Sue Mei Tan-Wong
- is at the Sir William Dunn School of Pathology , University of Oxford , Oxford , United Kingdom
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227
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Wahba L, Gore SK, Koshland D. The homologous recombination machinery modulates the formation of RNA-DNA hybrids and associated chromosome instability. eLife 2013; 2:e00505. [PMID: 23795288 PMCID: PMC3679537 DOI: 10.7554/elife.00505] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 05/02/2013] [Indexed: 12/24/2022] Open
Abstract
Genome instability in yeast and mammals is caused by RNA–DNA hybrids that form as a result of defects in different aspects of RNA biogenesis. We report that in yeast mutants defective for transcription repression and RNA degradation, hybrid formation requires Rad51p and Rad52p. These proteins normally promote DNA–DNA strand exchange in homologous recombination. We suggest they also directly promote the DNA–RNA strand exchange necessary for hybrid formation since we observed accumulation of Rad51p at a model hybrid-forming locus. Furthermore, we provide evidence that Rad51p mediates hybridization of transcripts to homologous chromosomal loci distinct from their site of synthesis. This hybrid formation in trans amplifies the genome-destabilizing potential of RNA and broadens the exclusive co-transcriptional models that pervade the field. The deleterious hybrid-forming activity of Rad51p is counteracted by Srs2p, a known Rad51p antagonist. Thus Srs2p serves as a novel anti-hybrid mechanism in vivo. DOI:http://dx.doi.org/10.7554/eLife.00505.001 Cells with an unusually large number of mutations—either in the form of changes to the DNA sequence or changes in the number or structure of chromosomes—are said to show genome instability. Although these mutations sometimes boost an organism's chances of survival and reproduction, they more often have detrimental effects, which can include cancer. Genome instability can arise as a result of mistakes occurring during the repair of damaged DNA, or due to inappropriate hybridization of RNA to its DNA template. These RNA–DNA hybrids had been thought to occur strictly during the transcription of DNA into RNA. During this process, the two strands of the DNA molecule separate behind the moving RNA polymerase, and this provides an opportunity for the newly formed RNA to hybridize back to its DNA template. When these RNA–DNA hybrids persist, they give rise to DNA damage that leads to genome instability. Although much is known about the factors that prevent the formation of hybrids, or promote their removal, little is known about how hybrids form in the first place. Now, Wahba et al. have identified one such mechanism in the model yeast, Saccharomyces cerevisiae. It involves a protein called Rad51p, which helps to join stretches of nucleic acids together to repair breaks in DNA. However, Wahba et al. showed that if Rad51p is not properly regulated, it can also trigger the formation of RNA–DNA hybrids; yeast cells that lack the gene for Rad51p showed significantly reduced levels of hybrid formation. Moreover, dysfunctional Rad51p causes RNA sequences to anneal to DNA throughout the genome, rather than just at the site in which the RNA was originally produced. This means that RNA sequences produced during transcription are much more of a threat to genomic stability than previously thought. The work of Wahba et al. presents a paradox in which a protein that is normally involved in repairing DNA can itself cause damage if it is not carefully regulated. It also raises the possibility that the elevated levels of Rad51p expression observed in cancer cells could be a cause, rather than a consequence, of mutations. DOI:http://dx.doi.org/10.7554/eLife.00505.002
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Affiliation(s)
- Lamia Wahba
- Department of Cell and Molecular Biology , Howard Hughes Medical Institute, University of California, Berkeley , Berkeley , United States ; Department of Biology , Johns Hopkins University , Baltimore , United States
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228
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Porrua O, Libri D. A bacterial-like mechanism for transcription termination by the Sen1p helicase in budding yeast. Nat Struct Mol Biol 2013; 20:884-91. [PMID: 23748379 DOI: 10.1038/nsmb.2592] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 04/22/2013] [Indexed: 12/25/2022]
Abstract
Transcription termination is essential to generate functional RNAs and to prevent disruptive polymerase collisions resulting from concurrent transcription. The yeast Sen1p helicase is involved in termination of most noncoding RNAs transcribed by RNA polymerase II (RNAPII). However, the mechanism of termination and the role of this protein have remained enigmatic. Here we address the mechanism of Sen1p-dependent termination by using a highly purified in vitro system. We show that Sen1p is the key enzyme of the termination reaction and reveal features of the termination mechanism. Like the bacterial termination factor Rho, Sen1p recognizes the nascent RNA and hydrolyzes ATP to dissociate the elongation complex. Sen1p-dependent termination is highly specific and, notably, does not require the C-terminal domain of RNAPII. We also show that termination is inhibited by RNA-DNA hybrids. Our results elucidate the role of Sen1p in controlling pervasive transcription.
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Affiliation(s)
- Odil Porrua
- Centre de Génétique Moléculaire, Centre National de la Recherche Scientifique, Gif sur Yvette, France.
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229
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Gavaldá S, Gallardo M, Luna R, Aguilera A. R-loop mediated transcription-associated recombination in trf4Δ mutants reveals new links between RNA surveillance and genome integrity. PLoS One 2013; 8:e65541. [PMID: 23762389 PMCID: PMC3676323 DOI: 10.1371/journal.pone.0065541] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 04/25/2013] [Indexed: 01/13/2023] Open
Abstract
To get further insight into the factors involved in the maintenance of genome integrity we performed a screening of Saccharomyces cerevisiae deletion strains inducing hyperrecombination. We have identified trf4, a gene encoding a non-canonical polyA-polymerase involved in RNA surveillance, as a factor that prevents recombination between DNA repeats. We show that trf4Δ confers a transcription-associated recombination phenotype that is mediated by the nascent mRNA. In addition, trf4Δ also leads to an increase in the mutation frequency. Both genetic instability phenotypes can be suppressed by overexpression of RNase H and are exacerbated by overexpression of the human cytidine deaminase AID. These results suggest that in the absence of Trf4 R-loops accumulate co-transcriptionally increasing the recombination and mutation frequencies. Altogether our data indicate that Trf4 is necessary for both mRNA surveillance and maintenance of genome integrity, serving as a link between RNA and DNA metabolism in S. cerevisiae.
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Affiliation(s)
- Sandra Gavaldá
- Departamento de Biología Molecular, Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | | | - Rosa Luna
- Departamento de Biología Molecular, Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Andrés Aguilera
- Departamento de Biología Molecular, Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
- * E-mail:
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230
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Montecucco A, Biamonti G. Pre-mRNA processing factors meet the DNA damage response. Front Genet 2013; 4:102. [PMID: 23761808 PMCID: PMC3674313 DOI: 10.3389/fgene.2013.00102] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/20/2013] [Indexed: 12/04/2022] Open
Abstract
It is well-known that DNA-damaging agents induce genome instability, but only recently have we begun to appreciate that chromosomes are fragile per se and frequently subject to DNA breakage. DNA replication further magnifies such fragility, because it leads to accumulation of single-stranded DNA. Recent findings suggest that chromosome fragility is similarly increased during transcription. Transcripts produced by RNA polymerase II (RNAPII) are subject to multiple processing steps, including maturation of 5′ and 3′ ends and splicing, followed by transport to the cytoplasm. RNA maturation starts on nascent transcripts and is mediated by a number of diverse proteins and ribonucleoprotein particles some of which are recruited cotranscriptionally through interactions with the carboxy-terminal domain of RNAPII. This coupling is thought to maximize efficiency of pre-mRNA maturation and directly impacts the choice of alternative splice sites. Mounting evidence suggests that lack of coordination among different RNA maturation steps, by perturbing the interaction of nascent transcripts with the DNA template, has deleterious effects on genome stability. Thus, in the absence of proper surveillance mechanisms, transcription could be a major source of DNA damage in cancer. Recent high-throughput screenings in human cells and budding yeast have identified several factors implicated in RNA metabolism that are targets of DNA damage checkpoint kinases: ATM (ataxia telangiectasia mutated) and ATR (ATM-Rad3 related) (Tel1 and Mec1 in budding yeast, respectively). Moreover, inactivation of various RNA processing factors induces accumulation of γH2AX foci, an early sign of DNA damage. Thus, a complex network is emerging that links DNA repair and RNA metabolism. In this review we provide a comprehensive overview of the role played by pre-mRNA processing factors in the cell response to DNA damage and in the maintenance of genome stability.
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231
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Lavin MF, Yeo AJ, Becherel OJ. Senataxin protects the genome: Implications for neurodegeneration and other abnormalities. Rare Dis 2013; 1:e25230. [PMID: 25003001 PMCID: PMC3927485 DOI: 10.4161/rdis.25230] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/31/2013] [Indexed: 11/29/2022] Open
Abstract
Ataxia oculomotor apraxia type 2 (AOA2) is a rare autosomal recessive disorder characterized by cerebellar atrophy, peripheral neuropathy, loss of Purkinje cells and elevated α-fetoprotein. AOA2 is caused by mutations in the SETX gene that codes for the high molecular weight protein senataxin. Mutations in this gene also cause dominant neurodegenerative disorders. Similar to that observed for other autosomal recessive ataxias, this protein protects the integrity of the genome against oxidative and other forms of DNA damage to reduce the risk of neurodegeneration. Senataxin functions in transcription termination and RNA splicing and it has been shown to resolve RNA/DNA hybrids (R-loops) that arise at transcription pause sites or when transcription is blocked. Recent data suggest that this protein functions at the interface between transcription and DNA replication to minimise the risk of collision and maintain genome stability. Our recent data using SETX gene-disrupted mice revealed that male mice were defective in spermatogenesis and were infertile. DNA double strand-breaks persisted throughout meiosis and crossing-over failed in SETX mutant mice. These changes can be explained by the accumulation of R-loops, which interfere with Holiday junctions and crossing-over. We also showed that senataxin was localized to the XY body in pachytene cells and was involved in transcriptional silencing of these chromosomes. While the defect in meiotic recombination was striking in these animals, there was no evidence of neurodegeneration as observed in AOA2 patients. We discuss here potentially different roles for senataxin in proliferating and post-mitotic cells.
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Affiliation(s)
- Martin F Lavin
- Queensland Institute of Medical Research; Radiation Biology and Oncology; Brisbane, QLD, Australia ; University of Queensland Centre for Clinical Research; Herston, QLD, Australia
| | - Abrey J Yeo
- Queensland Institute of Medical Research; Radiation Biology and Oncology; Brisbane, QLD, Australia ; School of Medicine; University of Queensland; Herston, QLD, Australia
| | - Olivier J Becherel
- Queensland Institute of Medical Research; Radiation Biology and Oncology; Brisbane, QLD, Australia ; School of Chemistry & Molecular Biosciences; University of Queensland; St. Lucia, QLD, Australia
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Golla U, Singh V, Azad GK, Singh P, Verma N, Mandal P, Chauhan S, Tomar RS. Sen1p contributes to genomic integrity by regulating expression of ribonucleotide reductase 1 (RNR1) in Saccharomyces cerevisiae. PLoS One 2013; 8:e64798. [PMID: 23741394 PMCID: PMC3669351 DOI: 10.1371/journal.pone.0064798] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 04/18/2013] [Indexed: 12/29/2022] Open
Abstract
Gene expression is a multi-step process which requires recruitment of several factors to promoters. One of the factors, Sen1p is an RNA/DNA helicase implicated in transcriptional termination and RNA processing in yeast. In the present study, we have identified a novel function of Sen1p that regulates the expression of ribonucleotide reductase RNR1 gene, which is essential for maintaining genomic integrity. Cells with mutation in the helicase domain or lacking N-terminal domain of Sen1p displayed a drastic decrease in the basal level transcription of RNR1 gene and showed enhanced sensitivity to various DNA damaging agents. Moreover, SEN1 mutants [Sen1-1 (G1747D), Sen1-2 (Δ1-975)] exhibited defects in DNA damage checkpoint activation. Surprisingly, CRT1 deletion in Sen1p mutants (Sen1-1, Sen1-2) was partly able to rescue the slow growth phenotype upon genotoxic stress. Altogether, our observations suggest that Sen1p is required for cell protection against DNA damage by regulating the expression of DNA repair gene RNR1. Thus, the misregulation of Sen1p regulated genes can cause genomic instability that may lead to neurological disorders and premature aging.
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Affiliation(s)
- Upendarrao Golla
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Vikash Singh
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Gajendra Kumar Azad
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Prabhat Singh
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Naveen Verma
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Papita Mandal
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Sakshi Chauhan
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
| | - Raghuvir S. Tomar
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India
- * E-mail:
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Abstract
A number of DNA repair disorders are known to cause neurological problems. These disorders can be broadly characterised into early developmental, mid-to-late developmental or progressive. The exact developmental processes that are affected can influence disease pathology, with symptoms ranging from early embryonic lethality to late-onset ataxia. The category these diseases belong to depends on the frequency of lesions arising in the brain, the role of the defective repair pathway, and the nature of the mutation within the patient. Using observations from patients and transgenic mice, we discuss the importance of double strand break repair during neuroprogenitor proliferation and brain development and the repair of single stranded lesions in neuronal function and maintenance.
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Affiliation(s)
- Stuart L Rulten
- Genome Damage and Stability Centre, Science Park Road, Falmer, Brighton BN1 9RQ, UK.
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235
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Gaillard H, Herrera-Moyano E, Aguilera A. Transcription-associated genome instability. Chem Rev 2013; 113:8638-61. [PMID: 23597121 DOI: 10.1021/cr400017y] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla , Av. Américo Vespucio s/n, 41092 Seville, Spain
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Winsor TS, Bartkowiak B, Bennett CB, Greenleaf AL. A DNA damage response system associated with the phosphoCTD of elongating RNA polymerase II. PLoS One 2013; 8:e60909. [PMID: 23613755 PMCID: PMC3629013 DOI: 10.1371/journal.pone.0060909] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/04/2013] [Indexed: 01/22/2023] Open
Abstract
RNA polymerase II translocates across much of the genome and since it can be blocked by many kinds of DNA lesions, detects DNA damage proficiently; it thereby contributes to DNA repair and to normal levels of DNA damage resistance. However, the components and mechanisms that respond to polymerase blockage are largely unknown, except in the case of UV-induced damage that is corrected by nucleotide excision repair. Because elongating RNAPII carries with it numerous proteins that bind to its hyperphosphorylated CTD, we tested for effects of interfering with this binding. We find that expressing a decoy CTD-carrying protein in the nucleus, but not in the cytoplasm, leads to reduced DNA damage resistance. Likewise, inducing aberrant phosphorylation of the CTD, by deleting CTK1, reduces damage resistance and also alters rates of homologous recombination-mediated repair. In line with these results, extant data sets reveal a remarkable, highly significant overlap between phosphoCTD-associating protein genes and DNA damage-resistance genes. For one well-known phosphoCTD-associating protein, the histone methyltransferase Set2, we demonstrate a role in DNA damage resistance, and we show that this role requires the phosphoCTD binding ability of Set2; surprisingly, Set2’s role in damage resistance does not depend on its catalytic activity. To explain all of these observations, we posit the existence of a CTD-Associated DNA damage Response (CAR) system, organized around the phosphoCTD of elongating RNAPII and comprising a subset of phosphoCTD-associating proteins.
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Affiliation(s)
- Tiffany Sabin Winsor
- Department of Biochemistry, Duke Center for RNA Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bartlomiej Bartkowiak
- Department of Biochemistry, Duke Center for RNA Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Craig B. Bennett
- Department of Biochemistry, Duke Center for RNA Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Arno L. Greenleaf
- Department of Biochemistry, Duke Center for RNA Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Becherel OJ, Yeo AJ, Stellati A, Heng EYH, Luff J, Suraweera AM, Woods R, Fleming J, Carrie D, McKinney K, Xu X, Deng C, Lavin MF. Senataxin plays an essential role with DNA damage response proteins in meiotic recombination and gene silencing. PLoS Genet 2013; 9:e1003435. [PMID: 23593030 PMCID: PMC3623790 DOI: 10.1371/journal.pgen.1003435] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 02/12/2013] [Indexed: 12/28/2022] Open
Abstract
Senataxin, mutated in the human genetic disorder ataxia with oculomotor apraxia type 2 (AOA2), plays an important role in maintaining genome integrity by coordination of transcription, DNA replication, and the DNA damage response. We demonstrate that senataxin is essential for spermatogenesis and that it functions at two stages in meiosis during crossing-over in homologous recombination and in meiotic sex chromosome inactivation (MSCI). Disruption of the Setx gene caused persistence of DNA double-strand breaks, a defect in disassembly of Rad51 filaments, accumulation of DNA:RNA hybrids (R-loops), and ultimately a failure of crossing-over. Senataxin localised to the XY body in a Brca1-dependent manner, and in its absence there was incomplete localisation of DNA damage response proteins to the XY chromosomes and ATR was retained on the axial elements of these chromosomes, failing to diffuse out into chromatin. Furthermore persistence of RNA polymerase II activity, altered ubH2A distribution, and abnormal XY-linked gene expression in Setx−/− revealed an essential role for senataxin in MSCI. These data support key roles for senataxin in coordinating meiotic crossing-over with transcription and in gene silencing to protect the integrity of the genome. Ataxia with oculomotor apraxia type 2 (AOA2) caused by a defect in the gene Setx (coding for senataxin) is part of a subgroup of autosomal recessive ataxias characterized by defects in genes responsible for the recognition and/or repair of damage in DNA. Cells from these patients are characterized by oxidative stress and are defective in RNA processing and termination of transcription. Recent data suggest that senataxin is involved in coordinating events between DNA replication forks and ongoing transcription. To further understand the role of senataxin, we disrupted the Setx gene in mice and demonstrated its essential role in spermatogenesis during meiotic recombination and in meiotic sex chromosome inactivation (MSCI). In the absence of senataxin, DNA double-strand breaks persist, RNA:DNA hybrids (R-loops) accumulate, and homologous recombination is disrupted. Senataxin localised to the XY chromosomes during pachytene. This was dependent on Brca1, which functions early in MSCI to recruit DNA damage response proteins to the XY body. In the absence of senataxin, there was incomplete accumulation of DNA damage response proteins on the XY chromosomes and no MDC1-dependent diffusion of ATR to the broader XY chromatin. The end result was a defect in MSCI, apoptosis, and a failure to complete meiosis.
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Affiliation(s)
- Olivier J. Becherel
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Australia
| | - Abrey J. Yeo
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
- School of Medicine, University of Queensland, Brisbane, Australia
| | - Alissa Stellati
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Australia
| | - Evelyn Y. H. Heng
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
| | - John Luff
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
| | - Amila M. Suraweera
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
| | - Rick Woods
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
| | | | - Dianne Carrie
- QCF Transgenics Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
| | - Kristine McKinney
- Dana Farber Cancer Institute, Harvard University, Boston, Massachusetts, United States of America
| | - Xiaoling Xu
- Mammalian Genetics Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Chuxia Deng
- Mammalian Genetics Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Martin F. Lavin
- Radiation Biology and Oncology Laboratory, Queensland Institute of Medical Research, Brisbane, Australia
- University of Queensland Centre for Clinical Research, University of Queensland, Brisbane, Australia
- * E-mail:
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238
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Andersen PK, Jensen TH, Lykke-Andersen S. Making ends meet: coordination between RNA 3'-end processing and transcription initiation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:233-46. [PMID: 23450686 DOI: 10.1002/wrna.1156] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
RNA polymerase II (RNAPII)-mediated gene transcription initiates at promoters and ends at terminators. Transcription termination is intimately connected to 3'-end processing of the produced RNA and already when loaded at the promoter, RNAPII starts to become configured for this downstream event. Conversely, RNAPII is 'reset' as part of the 3'-end processing/termination event, thus preparing the enzyme for its next round of transcription--possibly on the same gene. There is both direct and circumstantial evidence for preferential recycling of RNAPII from the gene terminator back to its own promoter, which supposedly increases the efficiency of the transcription process under conditions where RNAPII levels are rate limiting. Here, we review differences and commonalities between initiation and 3'-end processing/termination processes on various types of RNAPII transcribed genes. In doing so, we discuss the requirements for efficient 3'-end processing/termination and how these may relate to proper recycling of RNAPII.
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Affiliation(s)
- Pia K Andersen
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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239
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Alzu A, Bermejo R, Begnis M, Lucca C, Piccini D, Carotenuto W, Saponaro M, Brambati A, Cocito A, Foiani M, Liberi G. Senataxin associates with replication forks to protect fork integrity across RNA-polymerase-II-transcribed genes. Cell 2013; 151:835-846. [PMID: 23141540 PMCID: PMC3494831 DOI: 10.1016/j.cell.2012.09.041] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 07/10/2012] [Accepted: 09/20/2012] [Indexed: 01/01/2023]
Abstract
Transcription hinders replication fork progression and stability. The ATR checkpoint and specialized DNA helicases assist DNA synthesis across transcription units to protect genome integrity. Combining genomic and genetic approaches together with the analysis of replication intermediates, we searched for factors coordinating replication with transcription. We show that the Sen1/Senataxin DNA/RNA helicase associates with forks, promoting their progression across RNA polymerase II (RNAPII)-transcribed genes. sen1 mutants accumulate aberrant DNA structures and DNA-RNA hybrids while forks clash head-on with RNAPII transcription units. These replication defects correlate with hyperrecombination and checkpoint activation in sen1 mutants. The Sen1 function at the forks is separable from its role in RNA processing. Our data, besides unmasking a key role for Senataxin in coordinating replication with transcription, provide a framework for understanding the pathological mechanisms caused by Senataxin deficiencies and leading to the severe neurodegenerative diseases ataxia with oculomotor apraxia type 2 and amyotrophic lateral sclerosis 4.
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Affiliation(s)
- Amaya Alzu
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Rodrigo Bermejo
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Martina Begnis
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Chiara Lucca
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Daniele Piccini
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Walter Carotenuto
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Marco Saponaro
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Alessandra Brambati
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare del Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Andrea Cocito
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy
| | - Marco Foiani
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy; DSBB-Università degli Studi di Milano, Via Celoria 26, 20139 Milan, Italy
| | - Giordano Liberi
- The FIRC Institute of Molecular Oncology (IFOM) Foundation, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare del Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100 Pavia, Italy.
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240
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Yüce Ö, West SC. Senataxin, defective in the neurodegenerative disorder ataxia with oculomotor apraxia 2, lies at the interface of transcription and the DNA damage response. Mol Cell Biol 2013; 33:406-17. [PMID: 23149945 PMCID: PMC3554130 DOI: 10.1128/mcb.01195-12] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 11/05/2012] [Indexed: 12/11/2022] Open
Abstract
The neurodegenerative disorder ataxia with oculomotor apraxia 2 (AOA-2) is caused by defects in senataxin, a putative RNA/DNA helicase thought to be involved in the termination of transcription at RNA polymerase pause sites. RNA/DNA hybrids (R loops) that arise during transcription pausing lead to genome instability unless they are resolved efficiently. We found that senataxin forms distinct nuclear foci in S/G(2)-phase human cells and that the number of these foci increases in response to impaired DNA replication or DNA damage. Senataxin colocalizes with 53BP1, a key DNA damage response protein, and with other factors involved in DNA repair. Inhibition of transcription using α-amanitin, or the dissolution of R loops by transient expression of RNase H1, leads to the loss of senataxin foci. These results indicate that senataxin localizes to sites of collision between components of the replisome and the transcription apparatus and that it is targeted to R loops, where it plays an important role at the interface of transcription and the DNA damage response.
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Affiliation(s)
- Özlem Yüce
- London Research Institute, Cancer Research UK, Clare Hall Laboratories, South Mimms, Herts, United Kingdom
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241
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Rho-dependent transcription termination is essential to prevent excessive genome-wide R-loops in Escherichia coli. Proc Natl Acad Sci U S A 2012; 110:258-63. [PMID: 23251031 DOI: 10.1073/pnas.1213123110] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two pathways of transcription termination, factor-independent and -dependent, exist in bacteria. The latter pathway operates on nascent transcripts that are not simultaneously translated and requires factors Rho, NusG, and NusA, each of which is essential for viability of WT Escherichia coli. NusG and NusA are also involved in antitermination of transcription at the ribosomal RNA operons, as well as in regulating the rates of transcription elongation of all genes. We have used a bisulfite-sensitivity assay to demonstrate genome-wide increase in the occurrence of RNA-DNA hybrids (R-loops), including from antisense and read-through transcripts, in a nusG missense mutant defective for Rho-dependent termination. Lethality associated with complete deficiency of Rho and NusG (but not NusA) was rescued by ectopic expression of an R-loop-helicase UvsW, especially so on defined growth media. Our results suggest that factor-dependent transcription termination subserves a surveillance function to prevent translation-uncoupled transcription from generating R-loops, which would block replication fork progression and therefore be lethal, and that NusA performs additional essential functions as well in E. coli. Prevention of R-loop-mediated transcription-replication conflicts by cotranscriptional protein engagement of nascent RNA is emerging as a unifying theme among both prokaryotes and eukaryotes.
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242
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Hazelbaker DZ, Marquardt S, Wlotzka W, Buratowski S. Kinetic competition between RNA Polymerase II and Sen1-dependent transcription termination. Mol Cell 2012. [PMID: 23177741 DOI: 10.1016/j.molcel.2012.10.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The essential helicase-like protein Sen1 mediates termination of RNA Polymerase II (Pol II) transcription at snoRNAs and other noncoding RNAs in yeast. A mutation in the Pol II subunit Rpb1 that increases the elongation rate increases read-through transcription at Sen1-mediated terminators. Termination and growth defects in sen1 mutant cells are partially suppressed by a slowly transcribing Pol II mutant and are exacerbated by a faster-transcribing Pol II mutant. Deletion of the nuclear exosome subunit Rrp6 allows visualization of noncoding RNA intermediates that are terminated but not yet processed. Sen1 mutants or faster-transcribing Pol II increase the average lengths of preprocessed snoRNA, CUT, and SUT transcripts, while slowed Pol II transcription produces shorter transcripts. These connections between transcription rate and Sen1 activity support a model whereby kinetic competition between elongating Pol II and Sen1 helicase establishes the temporal and spatial window for early Pol II termination.
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Affiliation(s)
- Dane Z Hazelbaker
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
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243
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Tan-Wong SM, Zaugg JB, Camblong J, Xu Z, Zhang DW, Mischo HE, Ansari AZ, Luscombe NM, Steinmetz LM, Proudfoot NJ. Gene loops enhance transcriptional directionality. Science 2012; 338:671-5. [PMID: 23019609 PMCID: PMC3563069 DOI: 10.1126/science.1224350] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Eukaryotic genomes are extensively transcribed, forming both messenger RNAs (mRNAs) and noncoding RNAs (ncRNAs). ncRNAs made by RNA polymerase II often initiate from bidirectional promoters (nucleosome-depleted chromatin) that synthesize mRNA and ncRNA in opposite directions. We demonstrate that, by adopting a gene-loop conformation, actively transcribed mRNA encoding genes restrict divergent transcription of ncRNAs. Because gene-loop formation depends on a protein factor (Ssu72) that coassociates with both the promoter and the terminator, the inactivation of Ssu72 leads to increased synthesis of promoter-associated divergent ncRNAs, referred to as Ssu72-restricted transcripts (SRTs). Similarly, inactivation of individual gene loops by gene mutation enhances SRT synthesis. We demonstrate that gene-loop conformation enforces transcriptional directionality on otherwise bidirectional promoters.
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MESH Headings
- Exosome Multienzyme Ribonuclease Complex/metabolism
- Genes, Fungal
- Genome, Fungal
- Mutation
- Nucleic Acid Conformation
- Phosphoprotein Phosphatases/metabolism
- Promoter Regions, Genetic
- RNA Polymerase II/metabolism
- RNA Stability
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Untranslated/genetics
- RNA, Untranslated/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/metabolism
- Transcription, Genetic
- mRNA Cleavage and Polyadenylation Factors/metabolism
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Affiliation(s)
- Sue Mei Tan-Wong
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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244
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Mischo HE, Proudfoot NJ. Disengaging polymerase: terminating RNA polymerase II transcription in budding yeast. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:174-85. [PMID: 23085255 PMCID: PMC3793857 DOI: 10.1016/j.bbagrm.2012.10.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/01/2012] [Accepted: 10/05/2012] [Indexed: 11/29/2022]
Abstract
Termination of transcription by RNA polymerase II requires two distinct processes: The formation of a defined 3′ end of the transcribed RNA, as well as the disengagement of RNA polymerase from its DNA template. Both processes are intimately connected and equally pivotal in the process of functional messenger RNA production. However, research in recent years has elaborated how both processes can additionally be employed to control gene expression in qualitative and quantitative ways. This review embraces these new findings and attempts to paint a broader picture of how this final step in the transcription cycle is of critical importance to many aspects of gene regulation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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Affiliation(s)
- Hannah E Mischo
- Cancer Research UK London Research Institute, Blanche Lane South Mimms, Herts, UK.
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245
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Arana ME, Kerns RT, Wharey L, Gerrish KE, Bushel PR, Kunkel TA. Transcriptional responses to loss of RNase H2 in Saccharomyces cerevisiae. DNA Repair (Amst) 2012; 11:933-41. [PMID: 23079308 DOI: 10.1016/j.dnarep.2012.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/28/2012] [Accepted: 09/04/2012] [Indexed: 01/27/2023]
Abstract
We report here the transcriptional responses in Saccharomyces cerevisiae to deletion of the RNH201 gene encoding the catalytic subunit of RNase H2. Deleting RNH201 alters RNA expression of 349 genes by ≥1.5-fold (q-value <0.01), of which 123 are upregulated and 226 are downregulated. Differentially expressed genes (DEGs) include those involved in stress responses and genome maintenance, consistent with a role for RNase H2 in removing ribonucleotides incorporated into DNA during replication. Upregulated genes include several that encode subunits of RNA polymerases I and III, and genes involved in ribosomal RNA processing, ribosomal biogenesis and tRNA modification and processing, supporting a role for RNase H2 in resolving R-loops formed during transcription of rRNA and tRNA genes. A role in R-loop resolution is further suggested by a higher average GC-content proximal to the transcription start site of downregulated as compared to upregulated genes. Several DEGs are involved in telomere maintenance, supporting a role for RNase H2 in resolving RNA-DNA hybrids formed at telomeres. A large number of DEGs encode nucleases, helicases and genes involved in response to dsRNA viruses, observations that could be relevant to the nucleic acid species that elicit an innate immune response in RNase H2-defective humans.
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Affiliation(s)
- Mercedes E Arana
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
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Schmid M, Jensen TH. Transcription-associated quality control of mRNP. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:158-68. [PMID: 22982197 DOI: 10.1016/j.bbagrm.2012.08.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 08/24/2012] [Accepted: 08/29/2012] [Indexed: 01/06/2023]
Abstract
Although a prime purpose of transcription is to produce RNA, a substantial amount of transcript is nevertheless turned over very early in its lifetime. During transcription RNAs are matured by nucleases from longer precursors and activities are also employed to exert quality control over the RNA synthesis process so as to discard, retain or transcriptionally silence unwanted molecules. In this review we discuss the somewhat paradoxical circumstance that the retention or turnover of RNA is often linked to its synthesis. This occurs via the association of chromatin, or the transcription elongation complex, with RNA degradation (co)factors. Although our main focus is on protein-coding genes, we also discuss mechanisms of transcription-connected turnover of non-protein-coding RNA from where important general principles are derived. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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Affiliation(s)
- Manfred Schmid
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C., Denmark
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247
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Lin YL, Pasero P. Interference between DNA replication and transcription as a cause of genomic instability. Curr Genomics 2012; 13:65-73. [PMID: 22942676 PMCID: PMC3269018 DOI: 10.2174/138920212799034767] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 10/03/2011] [Accepted: 10/06/2011] [Indexed: 11/22/2022] Open
Abstract
Replication and transcription are key aspects of DNA metabolism that take place on the same template and potentially interfere with each other. Conflicts between these two activities include head-on or co-directional collisions between DNA and RNA polymerases, which can lead to the formation of DNA breaks and chromosome rearrangements. To avoid these deleterious consequences and prevent genomic instability, cells have evolved multiple mechanisms preventing replication forks from colliding with the transcription machinery. Yet, recent reports indicate that interference between replication and transcription is not limited to physical interactions between polymerases and that other cotranscriptional processes can interfere with DNA replication. These include DNA-RNA hybrids that assemble behind elongating RNA polymerases, impede fork progression and promote homologous recombination. Here, we discuss recent evidence indicating that R-loops represent a major source of genomic instability in all organisms, from bacteria to human, and are potentially implicated in cancer development.
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Affiliation(s)
- Yea-Lih Lin
- Institute of Human Genetics, CNRS-UPR1142, Montpellier, France
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248
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R-loops cause replication impairment and genome instability during meiosis. EMBO Rep 2012; 13:923-9. [PMID: 22878416 DOI: 10.1038/embor.2012.119] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 07/13/2012] [Accepted: 07/16/2012] [Indexed: 01/17/2023] Open
Abstract
R-loops are harmful structures with a negative impact on transcription and recombination during mitosis, but no information exists for meiosis. We used Saccharomyces cerevisiae and Caenorhabditis elegans THO mutants as a tool to determine the consequences of R-loops in meiosis. We found that both S. cerevisiae and C. elegans THO mutants show defective meiosis and an impairment of premeiotic replication as well as DNA-damage accumulation. Importantly, RNase H partially suppressed the replication impairment and the DNA-damage accumulation. We conclude that R-loops can form during meiosis causing replication impairment with deleterious results.
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249
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R loops: from transcription byproducts to threats to genome stability. Mol Cell 2012; 46:115-24. [PMID: 22541554 DOI: 10.1016/j.molcel.2012.04.009] [Citation(s) in RCA: 719] [Impact Index Per Article: 59.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 04/03/2012] [Accepted: 04/06/2012] [Indexed: 12/17/2022]
Abstract
RNA:DNA hybrid structures known as R loops were thought to be rare byproducts of transcription. In the last decade, however, accumulating evidence has pointed to a new view in which R loops form more frequently, impacting transcription and threatening genome integrity as a source of chromosome fragility and a potential cause of disease. Not surprisingly, cells have evolved mechanisms to prevent cotranscriptional R loop formation. Here we discuss the factors and cellular processes that control R loop formation and the mechanisms by which R loops may influence gene expression and the integrity of the genome.
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250
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Ivančić-Baće I, Al Howard J, Bolt EL. Tuning in to interference: R-loops and cascade complexes in CRISPR immunity. J Mol Biol 2012; 422:607-616. [PMID: 22743103 DOI: 10.1016/j.jmb.2012.06.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 06/13/2012] [Accepted: 06/16/2012] [Indexed: 12/26/2022]
Abstract
Stable RNA-DNA hybrids formed by invasion of an RNA strand into duplex DNA, termed R-loops, are notorious for provoking genome instability especially when they arise during transcription. However, in some instances (DNA replication and class switch recombination), R-loops are useful so long as their existence is carefully managed to avoid them persisting. A recent flow of research papers establishes a newly discovered use for R-loops as key intermediates in a prokaryotic immune system called CRISPR (Clustered Regularly Interspersed Short Palindromic Repeats). Structures and mechanism of ribonucleoprotein complexes ("Cascades") that form CRISPR R-loops highlight precision targeting of duplex DNA that has sequence characteristics marking it as foe, enabling nucleolytic destruction of DNA and recycling the Cascade. We review these significant recent breakthroughs in understanding targeting/interference stages of CRISPR immunity and discuss questions arising, including a possible link between targeting and adaptive immunity in prokaryotes.
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Affiliation(s)
- Ivana Ivančić-Baće
- Department of Molecular Biology, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - Jamieson Al Howard
- School of Biomedical Sciences, University of Nottingham Medical School, Queens Medical Centre, Nottingham NG7 2UH, UK
| | - Edward L Bolt
- School of Biomedical Sciences, University of Nottingham Medical School, Queens Medical Centre, Nottingham NG7 2UH, UK.
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