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Abram TJ, Pickering CR, Lang AK, Bass NE, Raja R, Meena C, Alousi AM, Myers JN, McDevitt JT, Gillenwater AM, Vigneswaran N. Risk Stratification of Oral Potentially Malignant Disorders in Fanconi Anemia Patients Using Autofluorescence Imaging and Cytology-On-A Chip Assay. Transl Oncol 2018; 11:477-486. [PMID: 29481998 PMCID: PMC5884187 DOI: 10.1016/j.tranon.2018.01.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 01/12/2018] [Accepted: 01/16/2018] [Indexed: 12/18/2022] Open
Abstract
Fanconi anemia (FA) is a hereditary genomic instability disorder with a predisposition to leukemia and oral squamous cell carcinomas (OSCCs). Hematopoietic stem cell transplantation (HSCT) facilitates cure of bone marrow failure and leukemia and thus extends life expectancy in FA patients; however, survival of hematologic malignancies increases the risk of OSCC in these patients. We developed a "cytology-on-a-chip" (COC)-based brush biopsy assay for monitoring patients with oral potentially malignant disorders (OPMDs). Using this COC assay, we measured and correlated the cellular morphometry and Minichromosome Maintenance Complex Component 2 (MCM2) expression levels in brush biopsy samples of FA patients' OPMD with clinical risk indicators such as loss of autofluorescence (LOF), HSCT status, and mutational profiles identified by next-generation sequencing. Statistically significant differences were found in several cytology measurements based on high-risk indicators such as LOF-positive and HSCT-positive status, including greater variation in cell area and chromatin distribution, higher MCM2 expression levels, and greater numbers of white blood cells and cells with enlarged nuclei. Higher OPMD risk scores were associated with differences in the frequency of nuclear aberrations and differed based on LOF and HSCT statuses. We identified mutation of FAT1 gene in five and NOTCH-2 and TP53 genes in two cases of FA patients' OPMD. The high-risk OPMD of a non-FA patient harbored FAT1, CASP8, and TP63 mutations. Use of COC assay in combination with visualization of LOF holds promise for the early diagnosis of high-risk OPMD. These minimally invasive diagnostic tools are valuable for long-term surveillance of OSCC in FA patients and avoidance of unwarranted scalpel biopsies.
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Affiliation(s)
- Timothy J Abram
- Rice University, Department of Bioengineering, Houston, Texas; New York University, Department of Biomaterials, New York, NY, USA
| | - Curtis R Pickering
- University of Texas M. D. Anderson Cancer Center, Department of Head and Neck Surgery, Houston, Texas, USA
| | - Alexander K Lang
- University of Texas School of Dentistry, Department of Diagnostic and Biomedical Sciences, Houston, Texas, USA
| | - Nancy E Bass
- University of Texas School of Dentistry, Department of Diagnostic and Biomedical Sciences, Houston, Texas, USA
| | - Rameez Raja
- Rice University, Department of Bioengineering, Houston, Texas; University of Texas School of Dentistry, Department of Diagnostic and Biomedical Sciences, Houston, Texas, USA
| | - Cynthia Meena
- University of Texas School of Dentistry, Department of Diagnostic and Biomedical Sciences, Houston, Texas, USA
| | - Amin M Alousi
- University of Texas M. D. Anderson Cancer Center, Department of Stem Cell Transplantation, Houston, Texas, USA
| | - Jeffrey N Myers
- University of Texas M. D. Anderson Cancer Center, Department of Head and Neck Surgery, Houston, Texas, USA
| | - John T McDevitt
- New York University, Department of Biomaterials, New York, NY, USA
| | - Ann M Gillenwater
- University of Texas M. D. Anderson Cancer Center, Department of Head and Neck Surgery, Houston, Texas, USA
| | - Nadarajah Vigneswaran
- University of Texas School of Dentistry, Department of Diagnostic and Biomedical Sciences, Houston, Texas, USA.
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202
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Garaycoechea JI, Crossan GP, Langevin F, Mulderrig L, Louzada S, Yang F, Guilbaud G, Park N, Roerink S, Nik-Zainal S, Stratton MR, Patel KJ. Alcohol and endogenous aldehydes damage chromosomes and mutate stem cells. Nature 2018; 553:171-177. [PMID: 29323295 PMCID: PMC6047743 DOI: 10.1038/nature25154] [Citation(s) in RCA: 246] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 11/21/2017] [Indexed: 12/13/2022]
Abstract
Haematopoietic stem cells renew blood. Accumulation of DNA damage in these cells promotes their decline, while misrepair of this damage initiates malignancies. Here we describe the features and mutational landscape of DNA damage caused by acetaldehyde, an endogenous and alcohol-derived metabolite. This damage results in DNA double-stranded breaks that, despite stimulating recombination repair, also cause chromosome rearrangements. We combined transplantation of single haematopoietic stem cells with whole-genome sequencing to show that this damage occurs in stem cells, leading to deletions and rearrangements that are indicative of microhomology-mediated end-joining repair. Moreover, deletion of p53 completely rescues the survival of aldehyde-stressed and mutated haematopoietic stem cells, but does not change the pattern or the intensity of genome instability within individual stem cells. These findings characterize the mutation of the stem-cell genome by an alcohol-derived and endogenous source of DNA damage. Furthermore, we identify how the choice of DNA-repair pathway and a stringent p53 response limit the transmission of aldehyde-induced mutations in stem cells.
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Affiliation(s)
- Juan I Garaycoechea
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Gerry P Crossan
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Frédéric Langevin
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Lee Mulderrig
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sandra Louzada
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Fentang Yang
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Guillaume Guilbaud
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Naomi Park
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Sophie Roerink
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | | | | | - Ketan J Patel
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Hills Rd, Cambridge CB2 0QQ, UK
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203
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Lafuente-Barquero J, Luke-Glaser S, Graf M, Silva S, Gómez-González B, Lockhart A, Lisby M, Aguilera A, Luke B. The Smc5/6 complex regulates the yeast Mph1 helicase at RNA-DNA hybrid-mediated DNA damage. PLoS Genet 2017; 13:e1007136. [PMID: 29281624 PMCID: PMC5760084 DOI: 10.1371/journal.pgen.1007136] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 01/09/2018] [Accepted: 11/28/2017] [Indexed: 01/08/2023] Open
Abstract
RNA-DNA hybrids are naturally occurring obstacles that must be overcome by the DNA replication machinery. In the absence of RNase H enzymes, RNA-DNA hybrids accumulate, resulting in replication stress, DNA damage and compromised genomic integrity. We demonstrate that Mph1, the yeast homolog of Fanconi anemia protein M (FANCM), is required for cell viability in the absence of RNase H enzymes. The integrity of the Mph1 helicase domain is crucial to prevent the accumulation of RNA-DNA hybrids and RNA-DNA hybrid-dependent DNA damage, as determined by Rad52 foci. Mph1 forms foci when RNA-DNA hybrids accumulate, e.g. in RNase H or THO-complex mutants and at short telomeres. Mph1, however is a double-edged sword, whose action at hybrids must be regulated by the Smc5/6 complex. This is underlined by the observation that simultaneous inactivation of RNase H2 and Smc5/6 results in Mph1-dependent synthetic lethality, which is likely due to an accumulation of toxic recombination intermediates. The data presented here support a model, where Mph1’s helicase activity plays a crucial role in responding to persistent RNA-DNA hybrids. DNA damage can either occur exogenously through DNA damaging agents such as UV light and exposure to chemotherapeutics, or endogenously via metabolic, cellular processes. The RNA product of transcription, for example, can engage in the formation of RNA-DNA hybrids. Such RNA-DNA hybrids can impede replication fork progression and cause genomic instability, a hallmark of cancer. The misregulation of RNA-DNA hybrids has also been implicated in several neurological disorders. Recently, it has become evident that RNA-DNA hybrids may also have beneficial roles and therefore, these structures have to be tightly controlled. We found that Mph1 (mutator phenotype 1), the budding yeast homolog of Fanconi Anemia protein M, counteracts the accumulation of RNA-DNA hybrids. The inactivation of MPH1 results in a severe growth defect when combined with mutations in the well-characterized RNase H enzymes, that degrade the RNA moiety of an RNA-DNA hybrid. Based on the data presented here, we propose a model, where Mph1 itself has to be kept in check by the SMC (structural maintenance of chromosome) 5/6 complex at replication forks stalled by RNA-DNA hybrids. Mph1 acts as a double-edged sword, as both its deletion and the inability to control its helicase activity cause DNA damage and growth arrest when RNA-DNA hybrids accumulate.
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Affiliation(s)
- Juan Lafuente-Barquero
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Avda. Americo Vespucio 24, Seville, Spain
| | - Sarah Luke-Glaser
- Institute of Molecular Biology (IMB), Mainz, Germany
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Marco Graf
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Sonia Silva
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Avda. Americo Vespucio 24, Seville, Spain
- Department of Biology, University of Copenhagen, Ole Maaloeesvej 5, Copenhagen N, Denmark
| | - Belén Gómez-González
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Avda. Americo Vespucio 24, Seville, Spain
| | | | - Michael Lisby
- Department of Biology, University of Copenhagen, Ole Maaloeesvej 5, Copenhagen N, Denmark
| | - Andrés Aguilera
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Avda. Americo Vespucio 24, Seville, Spain
- * E-mail: (BL); (AA)
| | - Brian Luke
- Institute of Molecular Biology (IMB), Mainz, Germany
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Institute of Neurobiology and Developmental Biology, JGU Mainz, Mainz, Germany
- * E-mail: (BL); (AA)
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204
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RecQ and Fe-S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions. Biochem Soc Trans 2017; 46:77-95. [PMID: 29273621 DOI: 10.1042/bst20170044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022]
Abstract
Helicases are molecular motors that play central roles in nucleic acid metabolism. Mutations in genes encoding DNA helicases of the RecQ and iron-sulfur (Fe-S) helicase families are linked to hereditary disorders characterized by chromosomal instabilities, highlighting the importance of these enzymes. Moreover, mono-allelic RecQ and Fe-S helicase mutations are associated with a broad spectrum of cancers. This review will discuss and contrast the specialized molecular functions and biological roles of RecQ and Fe-S helicases in DNA repair, the replication stress response, and the regulation of gene expression, laying a foundation for continued research in these important areas of study.
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205
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Sarkar K, Han SS, Wen KK, Ochs HD, Dupré L, Seidman MM, Vyas YM. R-loops cause genomic instability in T helper lymphocytes from patients with Wiskott-Aldrich syndrome. J Allergy Clin Immunol 2017; 142:219-234. [PMID: 29248492 DOI: 10.1016/j.jaci.2017.11.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 11/07/2017] [Accepted: 11/10/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND Wiskott-Aldrich syndrome (WAS), X-linked thrombocytopenia (XLT), and X-linked neutropenia, which are caused by WAS mutations affecting Wiskott-Aldrich syndrome protein (WASp) expression or activity, manifest in immunodeficiency, autoimmunity, genomic instability, and lymphoid and other cancers. WASp supports filamentous actin formation in the cytoplasm and gene transcription in the nucleus. Although the genetic basis for XLT/WAS has been clarified, the relationships between mutant forms of WASp and the diverse features of these disorders remain ill-defined. OBJECTIVE We sought to define how dysfunctional gene transcription is causally linked to the degree of TH cell deficiency and genomic instability in the XLT/WAS clinical spectrum. METHODS In human TH1- or TH2-skewing cell culture systems, cotranscriptional R-loops (RNA/DNA duplex and displaced single-stranded DNA) and DNA double-strand breaks (DSBs) were monitored in multiple samples from patients with XLT and WAS and in normal T cells depleted of WASp. RESULTS WASp deficiency provokes increased R-loops and R-loop-mediated DSBs in TH1 cells relative to TH2 cells. Mechanistically, chromatin occupancy of serine 2-unphosphorylated RNA polymerase II is increased, and that of topoisomerase 1, an R-loop preventing factor, is decreased at R-loop-enriched regions of IFNG and TBX21 (TH1 genes) in TH1 cells. These aberrations accompany increased unspliced (intron-retained) and decreased spliced mRNA of IFNG and TBX21 but not IL13 (TH2 gene). Significantly, increased cellular load of R-loops and DSBs, which are normalized on RNaseH1-mediated suppression of ectopic R-loops, inversely correlates with disease severity scores. CONCLUSION Transcriptional R-loop imbalance is a novel molecular defect causative in TH1 immunodeficiency and genomic instability in patients with WAS. The study proposes that cellular R-loop load could be used as a potential biomarker for monitoring symptom severity and prognostic outcome in the XLT-WAS clinical spectrum and could be targeted therapeutically.
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Affiliation(s)
- Koustav Sarkar
- Division of Pediatric Hematology-Oncology, Carver College of Medicine and the University of Iowa Stead Family Children's Hospital, Iowa City, Md
| | - Seong-Su Han
- Division of Pediatric Hematology-Oncology, Carver College of Medicine and the University of Iowa Stead Family Children's Hospital, Iowa City, Md
| | - Kuo-Kuang Wen
- Division of Pediatric Hematology-Oncology, Carver College of Medicine and the University of Iowa Stead Family Children's Hospital, Iowa City, Md
| | - Hans D Ochs
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, University of Washington, Seattle, Md
| | - Loïc Dupré
- INSERM, UMR1043, Centre de Physiopathologie de Toulouse Purpan, Toulouse, Md; Université Toulouse III Paul-Sabatier, Toulouse, Md; CNRS, UMR5282, Toulouse, Md; Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Md; CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Md
| | - Michael M Seidman
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health (NIH), NIH Biomedical Research Center, Baltimore, Md
| | - Yatin M Vyas
- Division of Pediatric Hematology-Oncology, Carver College of Medicine and the University of Iowa Stead Family Children's Hospital, Iowa City, Md.
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206
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Mollah ZUA, Quah HS, Graham KL, Jhala G, Krishnamurthy B, Dharma JFM, Chee J, Trivedi PM, Pappas EG, Mackin L, Chu EPF, Akazawa S, Fynch S, Hodson C, Deans AJ, Trapani JA, Chong MMW, Bird PI, Brodnicki TC, Thomas HE, Kay TWH. Granzyme A Deficiency Breaks Immune Tolerance and Promotes Autoimmune Diabetes Through a Type I Interferon-Dependent Pathway. Diabetes 2017; 66:3041-3050. [PMID: 28733313 DOI: 10.2337/db17-0517] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 07/13/2017] [Indexed: 11/13/2022]
Abstract
Granzyme A is a protease implicated in the degradation of intracellular DNA. Nucleotide complexes are known triggers of systemic autoimmunity, but a role in organ-specific autoimmune disease has not been demonstrated. To investigate whether such a mechanism could be an endogenous trigger for autoimmunity, we examined the impact of granzyme A deficiency in the NOD mouse model of autoimmune diabetes. Granzyme A deficiency resulted in an increased incidence in diabetes associated with accumulation of ssDNA in immune cells and induction of an interferon response in pancreatic islets. Central tolerance to proinsulin in transgenic NOD mice was broken on a granzyme A-deficient background. We have identified a novel endogenous trigger for autoimmune diabetes and an in vivo role for granzyme A in maintaining immune tolerance.
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Affiliation(s)
| | - Hong Sheng Quah
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Kate L Graham
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Gaurang Jhala
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Balasubramanian Krishnamurthy
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Joanna Francisca M Dharma
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Jonathan Chee
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Prerak M Trivedi
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Evan G Pappas
- St. Vincent's Institute, Fitzroy, Victoria, Australia
| | - Leanne Mackin
- St. Vincent's Institute, Fitzroy, Victoria, Australia
| | - Edward P F Chu
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | | | - Stacey Fynch
- St. Vincent's Institute, Fitzroy, Victoria, Australia
| | | | - Andrew J Deans
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Joseph A Trapani
- Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Mark M W Chong
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Phillip I Bird
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Thomas C Brodnicki
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Helen E Thomas
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Thomas W H Kay
- St. Vincent's Institute, Fitzroy, Victoria, Australia
- Department of Medicine, St. Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
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207
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Salas-Armenteros I, Pérez-Calero C, Bayona-Feliu A, Tumini E, Luna R, Aguilera A. Human THO-Sin3A interaction reveals new mechanisms to prevent R-loops that cause genome instability. EMBO J 2017; 36:3532-3547. [PMID: 29074626 DOI: 10.15252/embj.201797208] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 09/22/2017] [Accepted: 09/28/2017] [Indexed: 11/09/2022] Open
Abstract
R-loops, formed by co-transcriptional DNA-RNA hybrids and a displaced DNA single strand (ssDNA), fulfill certain positive regulatory roles but are also a source of genomic instability. One key cellular mechanism to prevent R-loop accumulation centers on the conserved THO/TREX complex, an RNA-binding factor involved in transcription elongation and RNA export that contributes to messenger ribonucleoprotein (mRNP) assembly, but whose precise function is still unclear. To understand how THO restrains harmful R-loops, we searched for new THO-interacting factors. We found that human THO interacts with the Sin3A histone deacetylase complex to suppress co-transcriptional R-loops, DNA damage, and replication impairment. Functional analyses show that histone hypo-acetylation prevents accumulation of harmful R-loops and RNA-mediated genomic instability. Diminished histone deacetylase activity in THO- and Sin3A-depleted cell lines correlates with increased R-loop formation, genomic instability, and replication fork stalling. Our study thus uncovers physical and functional crosstalk between RNA-binding factors and chromatin modifiers with a major role in preventing R-loop formation and RNA-mediated genome instability.
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Affiliation(s)
- Irene Salas-Armenteros
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Carmen Pérez-Calero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Aleix Bayona-Feliu
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Emanuela Tumini
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Rosa Luna
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide-Universidad de Sevilla, Seville, Spain
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208
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Chang EYC, Novoa CA, Aristizabal MJ, Coulombe Y, Segovia R, Chaturvedi R, Shen Y, Keong C, Tam AS, Jones SJM, Masson JY, Kobor MS, Stirling PC. RECQ-like helicases Sgs1 and BLM regulate R-loop-associated genome instability. J Cell Biol 2017; 216:3991-4005. [PMID: 29042409 PMCID: PMC5716281 DOI: 10.1083/jcb.201703168] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/16/2017] [Accepted: 09/18/2017] [Indexed: 01/01/2023] Open
Abstract
Sgs1, the orthologue of human Bloom's syndrome helicase BLM, is a yeast DNA helicase functioning in DNA replication and repair. We show that SGS1 loss increases R-loop accumulation and sensitizes cells to transcription-replication collisions. Yeast lacking SGS1 accumulate R-loops and γ-H2A at sites of Sgs1 binding, replication pausing regions, and long genes. The mutation signature of sgs1Δ reveals copy number changes flanked by repetitive regions with high R-loop-forming potential. Analysis of BLM in Bloom's syndrome fibroblasts or by depletion of BLM from human cancer cells confirms a role for Sgs1/BLM in suppressing R-loop-associated genome instability across species. In support of a potential direct effect, BLM is found physically proximal to DNA:RNA hybrids in human cells, and can efficiently unwind R-loops in vitro. Together, our data describe a conserved role for Sgs1/BLM in R-loop suppression and support an increasingly broad view of DNA repair and replication fork stabilizing proteins as modulators of R-loop-mediated genome instability.
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Affiliation(s)
| | - Carolina A Novoa
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
| | | | - Yan Coulombe
- Genome Stability Laboratory, Centre Hospitalier Universitaire de Québec Research Center, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Romulo Segovia
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
| | - Richa Chaturvedi
- Genome Stability Laboratory, Centre Hospitalier Universitaire de Québec Research Center, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Yaoqing Shen
- Michael Smith Genome Sciences Centre, Vancouver, Canada
| | - Christelle Keong
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
| | - Annie S Tam
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Steven J M Jones
- Michael Smith Genome Sciences Centre, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, Centre Hospitalier Universitaire de Québec Research Center, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Michael S Kobor
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Peter C Stirling
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada .,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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209
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Moriel-Carretero M, Ovejero S, Gérus-Durand M, Vryzas D, Constantinou A. Fanconi anemia FANCD2 and FANCI proteins regulate the nuclear dynamics of splicing factors. J Cell Biol 2017; 216:4007-4026. [PMID: 29030393 PMCID: PMC5716273 DOI: 10.1083/jcb.201702136] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 08/02/2017] [Accepted: 08/25/2017] [Indexed: 01/20/2023] Open
Abstract
Moriel-Carretero et al. show that the Fanconi anemia proteins FANCI and FANCD2 associate with the splicing factor SF3B1 and that DNA replication stress induces the FANCI-dependent release of SF3B1 from nuclear speckles. FANCI and FANCD2 prevent accumulation of postcatalytic intron lariats, suggesting that they help coordinate DNA replication and transcription. Proteins disabled in the cancer-prone disorder Fanconi anemia (FA) ensure the maintenance of chromosomal stability during DNA replication. FA proteins regulate replication dynamics, coordinate replication-coupled repair of interstrand DNA cross-links, and mitigate conflicts between replication and transcription. Here we show that FANCI and FANCD2 associate with splicing factor 3B1 (SF3B1), a key spliceosomal protein of the U2 small nuclear ribonucleoprotein (U2 snRNP). FANCI is in close proximity to SF3B1 in the nucleoplasm of interphase and mitotic cells. Furthermore, we find that DNA replication stress induces the release of SF3B1 from nuclear speckles in a manner that depends on FANCI and on the activity of the checkpoint kinase ATR. In chromatin, both FANCD2 and FANCI associate with SF3B1, prevent accumulation of postcatalytic intron lariats, and contribute to the timely eviction of splicing factors. We propose that FANCD2 and FANCI contribute to the organization of functional domains in chromatin, ensuring the coordination of DNA replication and cotranscriptional processes.
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Affiliation(s)
- María Moriel-Carretero
- Institute of Human Genetics, Centre National de la Recherche Scientifique UMR 9002, Université de Montpellier, Montpellier, France
| | - Sara Ovejero
- Institute of Human Genetics, Centre National de la Recherche Scientifique UMR 9002, Université de Montpellier, Montpellier, France
| | - Marie Gérus-Durand
- Institute of Human Genetics, Centre National de la Recherche Scientifique UMR 9002, Université de Montpellier, Montpellier, France
| | - Dimos Vryzas
- Institute of Human Genetics, Centre National de la Recherche Scientifique UMR 9002, Université de Montpellier, Montpellier, France
| | - Angelos Constantinou
- Institute of Human Genetics, Centre National de la Recherche Scientifique UMR 9002, Université de Montpellier, Montpellier, France
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210
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Tian Y, Shen X, Wang R, Klages-Mundt NL, Lynn EJ, Martin SK, Ye Y, Gao M, Chen J, Schlacher K, Li L. Constitutive role of the Fanconi anemia D2 gene in the replication stress response. J Biol Chem 2017; 292:20184-20195. [PMID: 29021208 DOI: 10.1074/jbc.m117.814780] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/29/2017] [Indexed: 12/12/2022] Open
Abstract
In response to DNA cross-linking damage, the Fanconi anemia (FA) core complex activates the FA pathway by monoubiquitinating Fanconi anemia complementation group D2 (FANCD2) for the initiation of the nucleolytic processing of the DNA cross-links and stabilization of stalled replication forks. Given that all the classic FA proteins coordinately monoubiquitinate FANCD2, it is unclear why losses of individual classic FA genes yield varying cellular sensitivities to cross-linking damage. To address this question, we generated cellular knock-out models of FA core complex components and FANCD2 and found that FANCD2-null mutants display higher levels of spontaneous chromosomal damage and hypersensitivity to replication-blocking lesions than Fanconi anemia complementation group L (FANCL)-null mutants, suggesting that FANCD2 provides a basal level of DNA protection countering endogenous lesions in the absence of monoubiquitination. FANCD2's ubiquitination-independent function is likely involved in optimized recruitment of nucleolytic activities for the processing and protection of stressed replication forks. Our results reveal that FANCD2 has a ubiquitination-independent role in countering endogenous levels of replication stress, a function that is critical for the maintenance of genomic stability.
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Affiliation(s)
- Yanyan Tian
- Departments of Experimental Radiation Biology, Houston, Texas 77030
| | - Xi Shen
- Departments of Experimental Radiation Biology, Houston, Texas 77030
| | - Rui Wang
- Departments of Experimental Radiation Biology, Houston, Texas 77030
| | - Naeh L Klages-Mundt
- Departments of Experimental Radiation Biology, Houston, Texas 77030; Programs in Genetics and Epigenetics, Houston, Texas 77030
| | - Erica J Lynn
- Departments of Experimental Radiation Biology, Houston, Texas 77030
| | - Sara K Martin
- Departments of Experimental Radiation Biology, Houston, Texas 77030; Programs in Genetics and Epigenetics, Houston, Texas 77030
| | - Yin Ye
- Departments of Experimental Radiation Biology, Houston, Texas 77030
| | - Min Gao
- Departments of Experimental Radiation Biology, Houston, Texas 77030
| | - Junjie Chen
- Departments of Experimental Radiation Biology, Houston, Texas 77030; Programs in Genetics and Epigenetics, Houston, Texas 77030
| | - Katharina Schlacher
- Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030; Cancer Biology, M. D. Anderson Cancer Center University of Texas Health Graduate School of Biomedical Sciences, Houston, Texas 77030
| | - Lei Li
- Departments of Experimental Radiation Biology, Houston, Texas 77030; Programs in Genetics and Epigenetics, Houston, Texas 77030.
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211
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Physical proximity of chromatin to nuclear pores prevents harmful R loop accumulation contributing to maintain genome stability. Proc Natl Acad Sci U S A 2017; 114:10942-10947. [PMID: 28973905 DOI: 10.1073/pnas.1707845114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During transcription, the mRNA may hybridize with DNA, forming an R loop, which can be physiological or pathological, constituting in this case a source of genomic instability. To understand the mechanism by which eukaryotic cells prevent harmful R loops, we used human activation-induced cytidine deaminase (AID) to identify genes preventing R loops. A screening of 400 Saccharomyces cerevisiae selected strains deleted in nuclear genes revealed that cells lacking the Mlp1/2 nuclear basket proteins show AID-dependent genomic instability and replication defects that were suppressed by RNase H1 overexpression. Importantly, DNA-RNA hybrids accumulated at transcribed genes in mlp1/2 mutants, indicating that Mlp1/2 prevents R loops. Consistent with the Mlp1/2 role in gene gating to nuclear pores, artificial tethering to the nuclear periphery of a transcribed locus suppressed R loops in mlp1∆ cells. The same occurred in THO-deficient hpr1∆ cells. We conclude that proximity of transcribed chromatin to the nuclear pore helps restrain pathological R loops.
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212
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Federico MB, Campodónico P, Paviolo NS, Gottifredi V. ACCIDENTAL DUPLICATION: Beyond interstrand crosslinks repair: Contribution of FANCD2 and other Fanconi Anemia proteins to the replication of DNA. Mutat Res 2017:S0027-5107(17)30167-7. [PMID: 28966006 DOI: 10.1016/j.mrfmmm.2017.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 09/24/2017] [Indexed: 11/30/2022]
Abstract
The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/ 10.1016/j.mrfmmm.2017.09.006. This duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Maria B Federico
- Cell Cycle and Genomic Stability Laboratory, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - Paola Campodónico
- Cell Cycle and Genomic Stability Laboratory, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - Natalia S Paviolo
- Cell Cycle and Genomic Stability Laboratory, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina
| | - Vanesa Gottifredi
- Cell Cycle and Genomic Stability Laboratory, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.
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213
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García-Pichardo D, Cañas JC, García-Rubio ML, Gómez-González B, Rondón AG, Aguilera A. Histone Mutants Separate R Loop Formation from Genome Instability Induction. Mol Cell 2017; 66:597-609.e5. [PMID: 28575656 DOI: 10.1016/j.molcel.2017.05.014] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 04/03/2017] [Accepted: 05/15/2017] [Indexed: 01/02/2023]
Abstract
R loops have positive physiological roles, but they can also be deleterious by causing genome instability, and the mechanisms for this are unknown. Here we identified yeast histone H3 and H4 mutations that facilitate R loops but do not cause instability. R loops containing single-stranded DNA (ssDNA), versus RNA-DNA hybrids alone, were demonstrated using ssDNA-specific human AID and bisulfite. Notably, they are similar size regardless of whether or not they induce genome instability. Contrary to mutants causing R loop-mediated instability, these histone mutants do not accumulate H3 serine-10 phosphate (H3S10-P). We propose a two-step mechanism in which, first, an altered chromatin facilitates R loops, and second, chromatin is modified, including H3S10-P, as a requisite for compromising genome integrity. Consistently, these histone mutations suppress the high H3S10 phosphorylation and genomic instability of hpr1 and sen1 mutants. Therefore, contrary to what was previously believed, R loops do not cause genome instability by themselves.
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Affiliation(s)
- Desiré García-Pichardo
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Juan C Cañas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - María L García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Ana G Rondón
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain.
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214
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Madireddy A, Kosiyatrakul ST, Boisvert RA, Herrera-Moyano E, García-Rubio ML, Gerhardt J, Vuono EA, Owen N, Yan Z, Olson S, Aguilera A, Howlett NG, Schildkraut CL. FANCD2 Facilitates Replication through Common Fragile Sites. Mol Cell 2017; 64:388-404. [PMID: 27768874 DOI: 10.1016/j.molcel.2016.09.017] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 08/08/2016] [Accepted: 09/14/2016] [Indexed: 12/27/2022]
Abstract
Common fragile sites (CFSs) are genomic regions that are unstable under conditions of replicative stress. Although the characteristics of CFSs that render them vulnerable to stress are associated mainly with replication, the cellular pathways that protect CFSs during replication remain unclear. Here, we identify and describe a role for FANCD2 as a trans-acting facilitator of CFS replication, in the absence of exogenous replicative stress. In the absence of FANCD2, replication forks stall within the AT-rich fragility core of CFS, leading to dormant origin activation. Furthermore, FANCD2 deficiency is associated with DNA:RNA hybrid formation at CFS-FRA16D, and inhibition of DNA:RNA hybrid formation suppresses replication perturbation. In addition, we also found that FANCD2 reduces the number of potential sites of replication initiation. Our data demonstrate that FANCD2 protein is required to ensure efficient CFS replication and provide mechanistic insight into how FANCD2 regulates CFS stability.
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Affiliation(s)
- Advaitha Madireddy
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | | | - Rebecca A Boisvert
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Emilia Herrera-Moyano
- Centro Andaluz de Biología Molecular y Medicina Regenerativa, Universidad de Sevilla, 41092 Seville, Spain
| | - María L García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa, Universidad de Sevilla, 41092 Seville, Spain
| | - Jeannine Gerhardt
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Elizabeth A Vuono
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Nichole Owen
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Zi Yan
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Susan Olson
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa, Universidad de Sevilla, 41092 Seville, Spain
| | - Niall G Howlett
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Carl L Schildkraut
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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215
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Nguyen HD, Yadav T, Giri S, Saez B, Graubert TA, Zou L. Functions of Replication Protein A as a Sensor of R Loops and a Regulator of RNaseH1. Mol Cell 2017; 65:832-847.e4. [PMID: 28257700 DOI: 10.1016/j.molcel.2017.01.029] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 12/05/2016] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
Abstract
R loop, a transcription intermediate containing RNA:DNA hybrids and displaced single-stranded DNA (ssDNA), has emerged as a major source of genomic instability. RNaseH1, which cleaves the RNA in RNA:DNA hybrids, plays an important role in R loop suppression. Here we show that replication protein A (RPA), an ssDNA-binding protein, interacts with RNaseH1 and colocalizes with both RNaseH1 and R loops in cells. In vitro, purified RPA directly enhances the association of RNaseH1 with RNA:DNA hybrids and stimulates the activity of RNaseH1 on R loops. An RPA binding-defective RNaseH1 mutant is not efficiently stimulated by RPA in vitro, fails to accumulate at R loops in cells, and loses the ability to suppress R loops and associated genomic instability. Thus, in addition to sensing DNA damage and replication stress, RPA is a sensor of R loops and a regulator of RNaseH1, extending the versatile role of RPA in suppression of genomic instability.
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Affiliation(s)
- Hai Dang Nguyen
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Tribhuwan Yadav
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Sumanprava Giri
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Borja Saez
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Timothy A Graubert
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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216
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Hamperl S, Bocek MJ, Saldivar JC, Swigut T, Cimprich KA. Transcription-Replication Conflict Orientation Modulates R-Loop Levels and Activates Distinct DNA Damage Responses. Cell 2017; 170:774-786.e19. [PMID: 28802045 DOI: 10.1016/j.cell.2017.07.043] [Citation(s) in RCA: 386] [Impact Index Per Article: 55.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 05/09/2017] [Accepted: 07/25/2017] [Indexed: 12/19/2022]
Abstract
Conflicts between transcription and replication are a potent source of DNA damage. Co-transcriptional R-loops could aggravate such conflicts by creating an additional barrier to replication fork progression. Here, we use a defined episomal system to investigate how conflict orientation and R-loop formation influence genome stability in human cells. R-loops, but not normal transcription complexes, induce DNA breaks and orientation-specific DNA damage responses during conflicts with replication forks. Unexpectedly, the replisome acts as an orientation-dependent regulator of R-loop levels, reducing R-loops in the co-directional (CD) orientation but promoting their formation in the head-on (HO) orientation. Replication stress and deregulated origin firing increase the number of HO collisions leading to genome-destabilizing R-loops. Our findings connect DNA replication to R-loop homeostasis and suggest a mechanistic basis for genome instability resulting from deregulated DNA replication, observed in cancer and other disease states.
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Affiliation(s)
- Stephan Hamperl
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Michael J Bocek
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Joshua C Saldivar
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tomek Swigut
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Karlene A Cimprich
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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217
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Vierra DA, Garzon JL, Rego MA, Adroved MM, Mauro M, Howlett NG. Modulation of the Fanconi anemia pathway via chemically induced changes in chromatin structure. Oncotarget 2017; 8:76443-76457. [PMID: 29100324 PMCID: PMC5652718 DOI: 10.18632/oncotarget.19470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 06/10/2017] [Indexed: 01/04/2023] Open
Abstract
Fanconi anemia (FA) is a rare disease characterized by congenital defects, bone marrow failure, and atypically early-onset cancers. The FA proteins function cooperatively to repair DNA interstrand crosslinks. A major step in the activation of the pathway is the monoubiquitination of the FANCD2 and FANCI proteins, and their recruitment to chromatin-associated nuclear foci. The regulation and function of FANCD2 and FANCI, however, is poorly understood. In addition, how chromatin state impacts pathway activation is also unknown. In this study, we have examined the influence of chromatin state on the activation of the FA pathway. We describe potent activation of FANCD2 and FANCI monoubiquitination and nuclear foci formation following treatment of cells with the histone methyltransferase inhibitor BRD4770. BRD4770-induced activation of the pathway does not occur via the direct induction of DNA damage or via the inhibition of the G9a histone methyltransferase, a mechanism previously proposed for this molecule. Instead, we show that BRD4770-inducible FANCD2 and FANCI monoubiquitination and nuclear foci formation may be a consequence of inhibition of the PRC2/EZH2 chromatin-modifying complex. In addition, we show that inhibition of the class I and II histone deacetylases leads to attenuated FANCD2 and FANCI monoubiquitination and nuclear foci formation. Our studies establish that chromatin state is a major determinant of the activation of the FA pathway and suggest an important role for the PRC2/EZH2 complex in the regulation of this critical tumor suppressor pathway.
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Affiliation(s)
- David A Vierra
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, U.S.A
| | - Jada L Garzon
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, U.S.A
| | | | - Morganne M Adroved
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, U.S.A
| | - Maurizio Mauro
- Department of Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, New York, New York, U.S.A
| | - Niall G Howlett
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, U.S.A
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218
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Hodroj D, Serhal K, Maiorano D. Ddx19 links mRNA nuclear export with progression of transcription and replication and suppresses genomic instability upon DNA damage in proliferating cells. Nucleus 2017; 8:489-495. [PMID: 28696814 DOI: 10.1080/19491034.2017.1348448] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The DEAD-box Helicase 19 (Ddx19) gene codes for an RNA helicase involved in both mRNA (mRNA) export from the nucleus into the cytoplasm and in mRNA translation. In unperturbed cells, Ddx19 localizes in the cytoplasm and at the cytoplasmic face of the nuclear pore. Here we review recent findings related to an additional Ddx19 function in the nucleus in resolving RNA:DNA hybrids (R-loops) generated during collision between transcription and replication, and upon DNA damage. Activation of a DNA damage response pathway dependent upon the ATR kinase, a major regulator of replication fork progression, stimulates translocation of the Ddx19 protein from the cytoplasm into the nucleus. Only nuclear Ddx19 is competent to resolve R-loops, and down regulation of Ddx19 expression induces DNA double strand breaks only in proliferating cells. Overall these observations put forward Ddx19 as an important novel mediator of the crosstalk between transcription and replication.
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Affiliation(s)
- Dana Hodroj
- a Institute of Human Genetics, UMR9002 CNRS-UM, 141, Montpellier , France
| | - Kamar Serhal
- a Institute of Human Genetics, UMR9002 CNRS-UM, 141, Montpellier , France
| | - Domenico Maiorano
- a Institute of Human Genetics, UMR9002 CNRS-UM, 141, Montpellier , France
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219
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Aguilera A, Gómez-González B. DNA-RNA hybrids: the risks of DNA breakage during transcription. Nat Struct Mol Biol 2017; 24:439-443. [PMID: 28471430 DOI: 10.1038/nsmb.3395] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/05/2017] [Indexed: 12/28/2022]
Abstract
Although R loops can occur at different genomic locations, the factors that determine their formation and frequency remain unclear. Emerging evidence indicates that DNA breaks stimulate DNA-RNA hybrid formation. Here, we discuss the possibility that formation of hybrids may be an inevitable risk of DNA breaks that occur within actively transcribed regions. While such hybrids must be removed to permit repair, their potential role as repair intermediates remains to be established.
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Affiliation(s)
- Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
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220
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FANCM, BRCA1, and BLM cooperatively resolve the replication stress at the ALT telomeres. Proc Natl Acad Sci U S A 2017; 114:E5940-E5949. [PMID: 28673972 DOI: 10.1073/pnas.1708065114] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In the mammalian genome, certain genomic loci/regions pose greater challenges to the DNA replication machinery (i.e., the replisome) than others. Such known genomic loci/regions include centromeres, common fragile sites, subtelomeres, and telomeres. However, the detailed mechanism of how mammalian cells cope with the replication stress at these loci/regions is largely unknown. Here we show that depletion of FANCM, or of one of its obligatory binding partners, FAAP24, MHF1, and MHF2, induces replication stress primarily at the telomeres of cells that use the alternative lengthening of telomeres (ALT) pathway as their telomere maintenance mechanism. Using the telomere-specific single-molecule analysis of replicated DNA technique, we found that depletion of FANCM dramatically reduces the replication efficiency at ALT telomeres. We further show that FANCM, BRCA1, and BLM are actively recruited to the ALT telomeres that are experiencing replication stress and that the recruitment of BRCA1 and BLM to these damaged telomeres is interdependent and is regulated by both ATR and Chk1. Mechanistically, we demonstrated that, in FANCM-depleted ALT cells, BRCA1 and BLM help to resolve the telomeric replication stress by stimulating DNA end resection and homologous recombination (HR). Consistent with their roles in resolving the replication stress induced by FANCM deficiency, simultaneous depletion of BLM and FANCM, or of BRCA1 and FANCM, leads to increased micronuclei formation and synthetic lethality in ALT cells. We propose that these synthetic lethal interactions can be explored for targeting the ALT cancers.
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221
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Bhatia V, Herrera-Moyano E, Aguilera A, Gómez-González B. The Role of Replication-Associated Repair Factors on R-Loops. Genes (Basel) 2017; 8:E171. [PMID: 28653981 PMCID: PMC5541304 DOI: 10.3390/genes8070171] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/19/2017] [Accepted: 06/20/2017] [Indexed: 12/12/2022] Open
Abstract
The nascent RNA can reinvade the DNA double helix to form a structure termed the R-loop, where a single-stranded DNA (ssDNA) is accompanied by a DNA-RNA hybrid. Unresolved R-loops can impede transcription and replication processes and lead to genomic instability by a mechanism still not fully understood. In this sense, a connection between R-loops and certain chromatin markers has been reported that might play a key role in R-loop homeostasis and genome instability. To counteract the potential harmful effect of R-loops, different conserved messenger ribonucleoprotein (mRNP) biogenesis and nuclear export factors prevent R-loop formation, while ubiquitously-expressed specific ribonucleases and DNA-RNA helicases resolve DNA-RNA hybrids. However, the molecular events associated with R-loop sensing and processing are not yet known. Given that R-loops hinder replication progression, it is plausible that some DNA replication-associated factors contribute to dissolve R-loops or prevent R-loop mediated genome instability. In support of this, R-loops accumulate in cells depleted of the BRCA1, BRCA2 or the Fanconi anemia (FA) DNA repair factors, indicating that they play an active role in R-loop dissolution. In light of these results, we review our current view of the role of replication-associated DNA repair pathways in preventing the harmful consequences of R-loops.
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Affiliation(s)
- Vaibhav Bhatia
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain.
| | - Emilia Herrera-Moyano
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain.
| | - Andrés Aguilera
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain.
| | - Belén Gómez-González
- Andalusian Center for Molecular Biology and Regenerative Medicine-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Av. Américo Vespucio 24, 41092 Seville, Spain.
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222
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Rowlands H, Dhavarasa P, Cheng A, Yankulov K. Forks on the Run: Can the Stalling of DNA Replication Promote Epigenetic Changes? Front Genet 2017; 8:86. [PMID: 28690636 PMCID: PMC5479891 DOI: 10.3389/fgene.2017.00086] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/06/2017] [Indexed: 11/13/2022] Open
Abstract
Built of DNA polymerases and multiple associated factors, the replication fork steadily progresses along the DNA template and faithfully replicates DNA. This model can be found in practically every textbook of genetics, with the more complex situation of chromatinized DNA in eukaryotes often viewed as a variation. However, the replication-coupled disassembly/reassembly of chromatin adds significant complexity to the whole replication process. During the course of eukaryotic DNA replication the forks encounter various conditions and numerous impediments. These include nucleosomes with a variety of post-translational modifications, euchromatin and heterochromatin, differentially methylated DNA, tightly bound proteins, active gene promoters and DNA loops. At such positions the forks slow down or even stall. Dedicated factors stabilize the fork and prevent its rotation or collapse, while other factors resolve the replication block and facilitate the resumption of elongation. The fate of histones during replication stalling and resumption is not well understood. In this review we briefly describe recent advances in our understanding of histone turnover during DNA replication and focus on the possible mechanisms of nucleosome disassembly/reassembly at paused replication forks. We propose that replication pausing provides opportunities for an epigenetic change of the associated locus.
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Affiliation(s)
- Hollie Rowlands
- Department of Molecular and Cellular Biology, University of Guelph, GuelphON, Canada
| | - Piriththiv Dhavarasa
- Department of Molecular and Cellular Biology, University of Guelph, GuelphON, Canada
| | - Ashley Cheng
- Department of Molecular and Cellular Biology, University of Guelph, GuelphON, Canada
| | - Krassimir Yankulov
- Department of Molecular and Cellular Biology, University of Guelph, GuelphON, Canada
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223
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Stafford JL, Dyson G, Levin NK, Chaudhry S, Rosati R, Kalpage H, Wernette C, Petrucelli N, Simon MS, Tainsky MA. Reanalysis of BRCA1/2 negative high risk ovarian cancer patients reveals novel germline risk loci and insights into missing heritability. PLoS One 2017; 12:e0178450. [PMID: 28591191 PMCID: PMC5462348 DOI: 10.1371/journal.pone.0178450] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 05/12/2017] [Indexed: 12/30/2022] Open
Abstract
While up to 25% of ovarian cancer (OVCA) cases are thought to be due to inherited factors, the majority of genetic risk remains unexplained. To address this gap, we sought to identify previously undescribed OVCA risk variants through the whole exome sequencing (WES) and candidate gene analysis of 48 women with ovarian cancer and selected for high risk of genetic inheritance, yet negative for any known pathogenic variants in either BRCA1 or BRCA2. In silico SNP analysis was employed to identify suspect variants followed by validation using Sanger DNA sequencing. We identified five pathogenic variants in our sample, four of which are in two genes featured on current multi-gene panels; (RAD51D, ATM). In addition, we found a pathogenic FANCM variant (R1931*) which has been recently implicated in familial breast cancer risk. Numerous rare and predicted to be damaging variants of unknown significance were detected in genes on current commercial testing panels, most prominently in ATM (n = 6) and PALB2 (n = 5). The BRCA2 variant p.K3326*, resulting in a 93 amino acid truncation, was overrepresented in our sample (odds ratio = 4.95, p = 0.01) and coexisted in the germline of these women with other deleterious variants, suggesting a possible role as a modifier of genetic penetrance. Furthermore, we detected loss of function variants in non-panel genes involved in OVCA relevant pathways; DNA repair and cell cycle control, including CHEK1, TP53I3, REC8, HMMR, RAD52, RAD1, POLK, POLQ, and MCM4. In summary, our study implicates novel risk loci as well as highlights the clinical utility for retesting BRCA1/2 negative OVCA patients by genomic sequencing and analysis of genes in relevant pathways.
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Affiliation(s)
- Jaime L. Stafford
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Gregory Dyson
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Nancy K. Levin
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Sophia Chaudhry
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Rita Rosati
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Hasini Kalpage
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Courtney Wernette
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Nancie Petrucelli
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Michael S. Simon
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Michael A. Tainsky
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
- Molecular Therapeutics Program, Karmanos Cancer Institute at Wayne State University School of Medicine, Detroit, MI, United States of America
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224
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A Class of Environmental and Endogenous Toxins Induces BRCA2 Haploinsufficiency and Genome Instability. Cell 2017; 169:1105-1118.e15. [PMID: 28575672 PMCID: PMC5457488 DOI: 10.1016/j.cell.2017.05.010] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 04/07/2017] [Accepted: 05/02/2017] [Indexed: 02/02/2023]
Abstract
Mutations truncating a single copy of the tumor suppressor, BRCA2, cause cancer susceptibility. In cells bearing such heterozygous mutations, we find that a cellular metabolite and ubiquitous environmental toxin, formaldehyde, stalls and destabilizes DNA replication forks, engendering structural chromosomal aberrations. Formaldehyde selectively depletes BRCA2 via proteasomal degradation, a mechanism of toxicity that affects very few additional cellular proteins. Heterozygous BRCA2 truncations, by lowering pre-existing BRCA2 expression, sensitize to BRCA2 haploinsufficiency induced by transient exposure to natural concentrations of formaldehyde. Acetaldehyde, an alcohol catabolite detoxified by ALDH2, precipitates similar effects. Ribonuclease H1 ameliorates replication fork instability and chromosomal aberrations provoked by aldehyde-induced BRCA2 haploinsufficiency, suggesting that BRCA2 inactivation triggers spontaneous mutagenesis during DNA replication via aberrant RNA-DNA hybrids (R-loops). These findings suggest a model wherein carcinogenesis in BRCA2 mutation carriers can be incited by compounds found pervasively in the environment and generated endogenously in certain tissues with implications for public health.
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225
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Halász L, Karányi Z, Boros-Oláh B, Kuik-Rózsa T, Sipos É, Nagy É, Mosolygó-L Á, Mázló A, Rajnavölgyi É, Halmos G, Székvölgyi L. RNA-DNA hybrid (R-loop) immunoprecipitation mapping: an analytical workflow to evaluate inherent biases. Genome Res 2017; 27:1063-1073. [PMID: 28341774 PMCID: PMC5453320 DOI: 10.1101/gr.219394.116] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/23/2017] [Indexed: 12/16/2022]
Abstract
The impact of R-loops on the physiology and pathology of chromosomes has been demonstrated extensively by chromatin biology research. The progress in this field has been driven by technological advancement of R-loop mapping methods that largely relied on a single approach, DNA-RNA immunoprecipitation (DRIP). Most of the DRIP protocols use the experimental design that was developed by a few laboratories, without paying attention to the potential caveats that might affect the outcome of RNA-DNA hybrid mapping. To assess the accuracy and utility of this technology, we pursued an analytical approach to estimate inherent biases and errors in the DRIP protocol. By performing DRIP-sequencing, qPCR, and receiver operator characteristic (ROC) analysis, we tested the effect of formaldehyde fixation, cell lysis temperature, mode of genome fragmentation, and removal of free RNA on the efficacy of RNA-DNA hybrid detection and implemented workflows that were able to distinguish complex and weak DRIP signals in a noisy background with high confidence. We also show that some of the workflows perform poorly and generate random answers. Furthermore, we found that the most commonly used genome fragmentation method (restriction enzyme digestion) led to the overrepresentation of lengthy DRIP fragments over coding ORFs, and this bias was enhanced at the first exons. Biased genome sampling severely compromised mapping resolution and prevented the assignment of precise biological function to a significant fraction of R-loops. The revised workflow presented herein is established and optimized using objective ROC analyses and provides reproducible and highly specific RNA-DNA hybrid detection.
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Affiliation(s)
- László Halász
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Zsolt Karányi
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Internal Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Beáta Boros-Oláh
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Tímea Kuik-Rózsa
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Éva Sipos
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biopharmacy, University of Debrecen, 4032 Debrecen, Hungary
| | - Éva Nagy
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Ágnes Mosolygó-L
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - Anett Mázló
- Department of Immunology, University of Debrecen, 4032 Debrecen, Hungary
| | - Éva Rajnavölgyi
- Department of Immunology, University of Debrecen, 4032 Debrecen, Hungary
| | - Gábor Halmos
- Department of Biopharmacy, University of Debrecen, 4032 Debrecen, Hungary
| | - Lóránt Székvölgyi
- MTA-DE Momentum, Genome Architecture and Recombination Research Group, Research Centre for Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
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226
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Nguyen DT, Voon HPJ, Xella B, Scott C, Clynes D, Babbs C, Ayyub H, Kerry J, Sharpe JA, Sloane-Stanley JA, Butler S, Fisher CA, Gray NE, Jenuwein T, Higgs DR, Gibbons RJ. The chromatin remodelling factor ATRX suppresses R-loops in transcribed telomeric repeats. EMBO Rep 2017; 18:914-928. [PMID: 28487353 DOI: 10.15252/embr.201643078] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 03/21/2017] [Accepted: 03/27/2017] [Indexed: 02/04/2023] Open
Abstract
ATRX is a chromatin remodelling factor found at a wide range of tandemly repeated sequences including telomeres (TTAGGG)n ATRX mutations are found in nearly all tumours that maintain their telomeres via the alternative lengthening of telomere (ALT) pathway, and ATRX is known to suppress this pathway. Here, we show that recruitment of ATRX to telomeric repeats depends on repeat number, orientation and, critically, on repeat transcription. Importantly, the transcribed telomeric repeats form RNA-DNA hybrids (R-loops) whose abundance correlates with the recruitment of ATRX Here, we show loss of ATRX is also associated with increased R-loop formation. Our data suggest that the presence of ATRX at telomeres may have a central role in suppressing deleterious DNA secondary structures that form at transcribed telomeric repeats, and this may account for the increased DNA damage, stalling of replication and homology-directed repair previously observed upon loss of ATRX function.
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Affiliation(s)
- Diu Tt Nguyen
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Hsiao Phin J Voon
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK.,Department of Biochemistry and Molecular Biology, The Biomedicine Discovery Institute, Monash University, Clayton, Vic., Australia
| | - Barbara Xella
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Caroline Scott
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - David Clynes
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Christian Babbs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Helena Ayyub
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jon Kerry
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jacqueline A Sharpe
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jackie A Sloane-Stanley
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Sue Butler
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Chris A Fisher
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Nicki E Gray
- Computational Biology Research Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Thomas Jenuwein
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Richard J Gibbons
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
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227
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Conflict Resolution in the Genome: How Transcription and Replication Make It Work. Cell 2017; 167:1455-1467. [PMID: 27912056 DOI: 10.1016/j.cell.2016.09.053] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 09/20/2016] [Accepted: 09/27/2016] [Indexed: 01/12/2023]
Abstract
The complex machineries involved in replication and transcription translocate along the same DNA template, often in opposing directions and at different rates. These processes routinely interfere with each other in prokaryotes, and mounting evidence now suggests that RNA polymerase complexes also encounter replication forks in higher eukaryotes. Indeed, cells rely on numerous mechanisms to avoid, tolerate, and resolve such transcription-replication conflicts, and the absence of these mechanisms can lead to catastrophic effects on genome stability and cell viability. In this article, we review the cellular responses to transcription-replication conflicts and highlight how these inevitable encounters shape the genome and impact diverse cellular processes.
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228
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Ishiai M, Sato K, Tomida J, Kitao H, Kurumizaka H, Takata M. Activation of the FA pathway mediated by phosphorylation and ubiquitination. Mutat Res 2017; 803-805:89-95. [PMID: 28552166 DOI: 10.1016/j.mrfmmm.2017.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 05/04/2017] [Accepted: 05/04/2017] [Indexed: 12/15/2022]
Abstract
Fanconi anemia (FA) is a devastating hereditary condition that impacts genome integrity, leading to clinical features such as skeletal and visceral organ malformations, attrition of bone marrow stem cells, and carcinogenesis. At least 21 proteins, when absent or defective, have been implicated in this disorder, and they together constitute the FA pathway, which functions in detection and repair of, and tolerance to, endogenous DNA damage. The damage primarily handled by the FA pathway has been assumed to be related to DNA interstrand crosslinks (ICLs). The FA pathway is activated upon ICL damage, and a hallmark of this activation is the mono-ubiquitination events of the key FANCD2-FANCI protein complex. Recent data have revealed unexpectedly complex details in the regulation of FA pathway activation by ICLs. In this short review, we summarize the knowledge accumulated over the years regarding how the FA pathway is activated via protein modifications.
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Affiliation(s)
- Masamichi Ishiai
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - Koichi Sato
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
| | - Junya Tomida
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - Hiroyuki Kitao
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.
| | - Minoru Takata
- Laboratory of DNA Damage Signaling, Department of Late Effects Studies, Radiation Biology Center, Kyoto University, Kyoto, Japan.
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229
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The importance of tying up loose (DNA) ends. Blood 2017; 129:2457-2458. [DOI: 10.1182/blood-2017-03-773184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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230
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Tran PLT, Pohl TJ, Chen CF, Chan A, Pott S, Zakian VA. PIF1 family DNA helicases suppress R-loop mediated genome instability at tRNA genes. Nat Commun 2017; 8:15025. [PMID: 28429714 PMCID: PMC5413955 DOI: 10.1038/ncomms15025] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/17/2017] [Indexed: 01/21/2023] Open
Abstract
Saccharomyces cerevisiae encodes two Pif1 family DNA helicases, Pif1 and Rrm3. Rrm3 promotes DNA replication past stable protein complexes at tRNA genes (tDNAs). We identify a new role for the Pif1 helicase: promotion of replication and suppression of DNA damage at tDNAs. Pif1 binds multiple tDNAs, and this binding is higher in rrm3Δ cells. Accumulation of replication intermediates and DNA damage at tDNAs is higher in pif1Δ rrm3Δ than in rrm3Δ cells. DNA damage at tDNAs in the absence of these helicases is suppressed by destabilizing R-loops while Pif1 and Rrm3 binding to tDNAs is increased upon R-loop stabilization. We propose that Rrm3 and Pif1 promote genome stability at tDNAs by displacing the stable multi-protein transcription complex and by removing R-loops. Thus, we identify tDNAs as a new source of R-loop-mediated DNA damage. Given their large number and high transcription rate, tDNAs may be a potent source of genome instability. The budding yeast genome encodes two Pif1 family helicases, Pif1 and Rrm3, previously shown to have distinct functions in the maintenance of telomeres and other aspects of genome stability. Here the authors identify a role for Pif1 (and Rrm3) in promoting DNA replication and suppressing R-loop mediated DNA damage at tRNA genes.
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Affiliation(s)
- Phong Lan Thao Tran
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - Thomas J Pohl
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - Chi-Fu Chen
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - Angela Chan
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - Sebastian Pott
- Department of Human Genetics, University of Chicago, 920 E 58th St, Chicago, Illinois 60637, USA
| | - Virginia A Zakian
- Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey 08544, USA
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231
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Hodroj D, Recolin B, Serhal K, Martinez S, Tsanov N, Abou Merhi R, Maiorano D. An ATR-dependent function for the Ddx19 RNA helicase in nuclear R-loop metabolism. EMBO J 2017; 36:1182-1198. [PMID: 28314779 DOI: 10.15252/embj.201695131] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 02/10/2017] [Accepted: 02/14/2017] [Indexed: 12/31/2022] Open
Abstract
Coordination between transcription and replication is crucial in the maintenance of genome integrity. Disturbance of these processes leads to accumulation of aberrant DNA:RNA hybrids (R-loops) that, if unresolved, generate DNA damage and genomic instability. Here we report a novel, unexpected role for the nucleopore-associated mRNA export factor Ddx19 in removing nuclear R-loops formed upon replication stress or DNA damage. We show, in live cells, that Ddx19 transiently relocalizes from the nucleopore to the nucleus upon DNA damage, in an ATR/Chk1-dependent manner, and that Ddx19 nuclear relocalization is required to clear R-loops. Ddx19 depletion induces R-loop accumulation, proliferation-dependent DNA damage and defects in replication fork progression. Further, we show that Ddx19 resolves R-loops in vitro via its helicase activity. Furthermore, mutation of a residue phosphorylated by Chk1 in Ddx19 disrupts its interaction with Nup214 and allows its nuclear relocalization. Finally, we show that Ddx19 operates in resolving R-loops independently of the RNA helicase senataxin. Altogether these observations put forward a novel, ATR-dependent function for Ddx19 in R-loop metabolism to preserve genome integrity in mammalian cells.
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Affiliation(s)
- Dana Hodroj
- Genome Surveillance and Stability Laboratory, Institute of Human Genetics, UMR9002, CNRS-UM, University of Montpellier, Montpellier Cedex 5, France.,Genomics and Health Laboratory, Biology Department, Faculty of Sciences, R. Hariri Campus, Lebanese University, Hadath, Lebanon
| | - Bénédicte Recolin
- Genome Surveillance and Stability Laboratory, Institute of Human Genetics, UMR9002, CNRS-UM, University of Montpellier, Montpellier Cedex 5, France
| | - Kamar Serhal
- Genome Surveillance and Stability Laboratory, Institute of Human Genetics, UMR9002, CNRS-UM, University of Montpellier, Montpellier Cedex 5, France
| | - Susan Martinez
- Genome Surveillance and Stability Laboratory, Institute of Human Genetics, UMR9002, CNRS-UM, University of Montpellier, Montpellier Cedex 5, France
| | - Nikolay Tsanov
- Genome Surveillance and Stability Laboratory, Institute of Human Genetics, UMR9002, CNRS-UM, University of Montpellier, Montpellier Cedex 5, France
| | - Raghida Abou Merhi
- Genomics and Health Laboratory, Biology Department, Faculty of Sciences, R. Hariri Campus, Lebanese University, Hadath, Lebanon
| | - Domenico Maiorano
- Genome Surveillance and Stability Laboratory, Institute of Human Genetics, UMR9002, CNRS-UM, University of Montpellier, Montpellier Cedex 5, France
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232
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Takada M, Nagai S, Haruta M, Sugino RP, Tozuka K, Takei H, Ohkubo F, Inoue K, Kurosumi M, Miyazaki M, Sato-Otsubo A, Sato Y, Ogawa S, Kaneko Y. BRCA1 alterations with additional defects in DNA damage response genes may confer chemoresistance to BRCA-like breast cancers treated with neoadjuvant chemotherapy. Genes Chromosomes Cancer 2017; 56:405-420. [PMID: 28124401 DOI: 10.1002/gcc.22445] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 01/15/2017] [Accepted: 01/18/2017] [Indexed: 12/30/2022] Open
Abstract
The BRCA-like phenotype is a feature that some sporadic breast cancers share with those occurring in BRCA1 or BRCA2 mutation carriers. As tumors with the phenotype have defects in the DNA damage response pathway, which may increase sensitivity to drugs such as DNA cross-linking agents and PARP inhibitors, a method to identify this phenotype is important. The prediction of chemoresistance, which frequently develops in these tumors, is also crucial for improving therapy. We examined genomic aberrations and BRCA1 promoter methylation in tumors of 73 breast cancer (20 HR-/HER2- and 53 HR+/HER2-) patients, who received neoadjuvant chemotherapy with anthracycline, cyclophosphamide, and taxane, using SNP array CGH and quantitative PCR. The methylation and/or loss or uniparental disomy (UPD) of BRCA1 (BRCA1 alterations) and the loss or UPD of BRCA2 (BRCA2 alterations) were detected in 27 (37%) and 21 (29%), respectively, of the 73 tumors. Tumors with BRCA1 or BRCA2 alterations were associated with a higher number of genomic aberrations (P < 0.001 and P < 0.001) and higher percentage of TP53 alterations (P < 0.001 and P < 0.001) than those without. Overall survival (OS) rates were similar between patients with or without BRCA1 or BRCA2 alterations. However, when 27 patients with BRCA1-altered tumors were classified into those with or without the loss or UPD of PALB2, PAGR1, RAD51B, FANCM, MLL4, or ERCC1/2 in tumors, patients with additional defects in DNA damage response genes had worse OS (P = 0.037, 0.045, 0.038, 0.044, 0.041, or 0.019) than those without. These defects may confer chemoresistance and predict poor outcomes in patients with BRCA1-altered breast cancer.
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Affiliation(s)
- Mamoru Takada
- Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan.,Department of General Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Shigenori Nagai
- Divisions of Breast Oncology, Saitama Cancer Center, Saitama, Japan
| | - Masayuki Haruta
- Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan
| | - Ryuichi P Sugino
- Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan
| | - Katsunori Tozuka
- Divisions of Breast Surgery, Saitama Cancer Center, Ina, Saitama, Japan
| | - Hiroyuki Takei
- Divisions of Breast Surgery, Saitama Cancer Center, Ina, Saitama, Japan
| | - Fumie Ohkubo
- Divisions of Breast Oncology, Saitama Cancer Center, Saitama, Japan
| | - Kenichi Inoue
- Divisions of Breast Oncology, Saitama Cancer Center, Saitama, Japan
| | | | - Masaru Miyazaki
- Department of General Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Aiko Sato-Otsubo
- Division of Tumor Biology, Department of Pathology, Kyoto University School of Medicine, Kyoto, Japan
| | - Yusuke Sato
- Division of Tumor Biology, Department of Pathology, Kyoto University School of Medicine, Kyoto, Japan
| | - Seishi Ogawa
- Division of Tumor Biology, Department of Pathology, Kyoto University School of Medicine, Kyoto, Japan
| | - Yasuhiko Kaneko
- Research Institute for Clinical Oncology, Saitama Cancer Center, Saitama, Japan
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233
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Ogawa LM, Baserga SJ. Crosstalk between the nucleolus and the DNA damage response. MOLECULAR BIOSYSTEMS 2017; 13:443-455. [PMID: 28112326 PMCID: PMC5340083 DOI: 10.1039/c6mb00740f] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nucleolar function and the cellular response to DNA damage have long been studied as distinct disciplines. New research and a new appreciation for proteins holding multiple functional roles, however, is beginning to change the way we think about the crosstalk among distinct cellular processes. Here, we focus on the crosstalk between the DNA damage response and the nucleolus, including a comprehensive review of the literature that reveals a role for conventional DNA repair proteins in ribosome biogenesis, and conversely, ribosome biogenesis proteins in DNA repair. Furthermore, with recent advances in nucleolar proteomics and a growing list of proteins that localize to the nucleolus, it is likely that we will continue to identify new DNA repair proteins with a nucleolar-specific role. Given the importance of ribosome biogenesis and DNA repair in essential cellular processes and the role that they play in diverse pathologies, continued elucidation of the overlap between these two disciplines will be essential to the advancement of both fields and to the development of novel therapeutics.
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Affiliation(s)
- L M Ogawa
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - S J Baserga
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA. and Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA and Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
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234
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Palovcak A, Liu W, Yuan F, Zhang Y. Maintenance of genome stability by Fanconi anemia proteins. Cell Biosci 2017; 7:8. [PMID: 28239445 PMCID: PMC5320776 DOI: 10.1186/s13578-016-0134-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/07/2016] [Indexed: 12/20/2022] Open
Abstract
Persistent dysregulation of the DNA damage response and repair in cells causes genomic instability. The resulting genetic changes permit alterations in growth and proliferation observed in virtually all cancers. However, an unstable genome can serve as a double-edged sword by providing survival advantages in the ability to evade checkpoint signaling, but also creating vulnerabilities through dependency on alternative genomic maintenance factors. The Fanconi anemia pathway comprises an intricate network of DNA damage signaling and repair that are critical for protection against genomic instability. The importance of this pathway is underlined by the severity of the cancer predisposing syndrome Fanconi anemia which can be caused by biallelic mutations in any one of the 21 genes known thus far. This review delineates the roles of the Fanconi anemia pathway and the molecular actions of Fanconi anemia proteins in confronting replicative, oxidative, and mitotic stress.
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Affiliation(s)
- Anna Palovcak
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Gautier Building Room 311, 1011 NW 15th Street, Miami, FL 33136 USA
| | - Wenjun Liu
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Gautier Building Room 311, 1011 NW 15th Street, Miami, FL 33136 USA
| | - Fenghua Yuan
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Gautier Building Room 311, 1011 NW 15th Street, Miami, FL 33136 USA
| | - Yanbin Zhang
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Gautier Building Room 311, 1011 NW 15th Street, Miami, FL 33136 USA
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Abstract
Genomic instability is a hallmark of cancer and a common feature of human disorders, characterized by growth defects, neurodegeneration, cancer predisposition, and aging. Recent evidence has shown that DNA replication stress is a major driver of genomic instability and tumorigenesis. Cells can undergo mitosis with under-replicated DNA or unresolved DNA structures, and specific pathways are dedicated to resolving these structures during mitosis, suggesting that mitotic rescue from replication stress (MRRS) is a key process influencing genome stability and cellular homeostasis. Deregulation of MRRS following oncogene activation or loss-of-function of caretaker genes may be the cause of chromosomal aberrations that promote cancer initiation and progression. In this review, we discuss the causes and consequences of replication stress, focusing on its persistence in mitosis as well as the mechanisms and factors involved in its resolution, and the potential impact of incomplete replication or aberrant MRRS on tumorigenesis, aging and disease.
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Affiliation(s)
- Michalis Fragkos
- a CNRS UMR8200 , University Paris-Saclay , Gustave Roussy, Villejuif , France
| | - Valeria Naim
- a CNRS UMR8200 , University Paris-Saclay , Gustave Roussy, Villejuif , France
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236
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Lakhi NA, Mizejewski GJ. Alpha-fetoprotein and Fanconi Anemia: Relevance to DNA Repair and Breast Cancer Susceptibility. Fetal Pediatr Pathol 2017; 36:49-61. [PMID: 27690720 DOI: 10.1080/15513815.2016.1225873] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Elevations of serum alpha-fetoprotein (sAFP) have been reported in fetal and infant states of anemia. Fanconi anemia (FA) belongs to a family of genetic instability disorders which lack the capability to repair DNA breaks. The lesion occurs at a checkpoint regulatory step of the G2 to mitotic transition, allowing FA cells to override cell-cycle arrest. FA DNA repair pathways contain complementation groups known as FANC proteins. FANC proteins form multi-protein complexes with BRCA proteins and are involved in homologous DNA repair. An impaired cascade in these events imparts an increased breast cancer susceptibility to female FA patients. Elevations of sAFP have availed this fetal protein to serve as a biomarker for FA disease. However, the origin of the synthesis of sAFA has not been determined in FA patients. We hypothesize that hematopoietic multipotent progenitor stem cells in the bone marrow are the source of sAFP production in FA patients.
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Affiliation(s)
- Nisha A Lakhi
- a Department of Obstetrics and Gynecology , Richmond University Medical Center , Staten Island , New York , USA
| | - Gerald J Mizejewski
- b Wadsworth Center , New York State Department of Health , Albany , New York , USA
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237
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Sander Effron S, Makvandi M, Lin L, Xu K, Li S, Lee H, Hou C, Pryma DA, Koch C, Mach RH. PARP-1 Expression Quantified by [ 18F]FluorThanatrace: A Biomarker of Response to PARP Inhibition Adjuvant to Radiation Therapy. Cancer Biother Radiopharm 2017; 32:9-15. [PMID: 28118040 DOI: 10.1089/cbr.2016.2133] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
INTRODUCTION Poly (ADP-ribose) polymerase 1 (PARP-1) is the major target of clinical PARP inhibitors and is a potential predictive biomarker for response to therapy. Due to the limited success of PARP inhibitors as monotherapy, investigators have shifted the clinical role of PARP inhibitors to the adjuvant setting. In this study, we evaluate the radiotracer [18F]FluorThanatrace ([18F]FTT) as a marker of PARP expression in vitro and the associated biological implications of PARP-1 expression in PARP inhibitor treatment adjuvant to radiation therapy. MATERIALS AND METHODS SNU-251 (BRCA1-mutant) and SKOV3 (BRCA1-WT) cell lines were evaluated in vitro by using the radiotracer [18F]FTT. Pharmacological binding assays were performed at baseline and were correlated with PARP-1 protein expression measured by Western blot protein analysis. Cell viability and clonogenic assays were used to characterize in vitro cytotoxicity for treatments, including: PARP inhibitors alone, radiation alone, and PARP inhibitor adjuvant to radiation. Western blot protein analysis was used to assess response to treatment by using γH2AX to measure DNA damage and PAR to measure the catalytic inhibition of PARP. RESULTS [18F]FTT was capable of measuring PARP-1 protein expression in vitro and corresponded to Western blot protein analysis at baseline. The addition of a PARP inhibitor enhanced radiation effects in both cell lines; however, a greater synergy was observed in the SNU-251 cell line that expresses a BRCA1 mutation and homologous recombination deficiency. Western blot protein analysis showed that the addition of a PARP inhibitor adjuvant to radiation increases DNA damage in both cell lines and reduces PARP enzymatic activity as measured by PAR. CONCLUSIONS In this work, we found that PARP-1 expression positively corresponds in vitro to the response of PARP inhibitors in combination with radiation therapy in ovarian cancer.
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Affiliation(s)
- Samuel Sander Effron
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Mehran Makvandi
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Lilie Lin
- 2 Department of Radiation Oncology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Kuiying Xu
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Shihong Li
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Hsiaoju Lee
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Catherine Hou
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Daniel A Pryma
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Cameron Koch
- 2 Department of Radiation Oncology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Robert H Mach
- 1 Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
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238
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Detectable clonal mosaicism in blood as a biomarker of cancer risk in Fanconi anemia. Blood Adv 2017; 1:319-329. [PMID: 29296947 DOI: 10.1182/bloodadvances.2016000943] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 12/11/2016] [Indexed: 01/28/2023] Open
Abstract
Detectable clonal mosaicism for large chromosomal events has been associated with aging and an increased risk of hematological and some solid cancers. We hypothesized that genetic cancer predisposition disorders, such as Fanconi anemia (FA), could manifest a high rate of chromosomal mosaic events (CMEs) in peripheral blood, which could be used as early biomarkers of cancer risk. We studied the prevalence of CMEs by single-nucleotide polymorphism (SNP) array in 130 FA patients' blood DNA and their impact on cancer risk. We detected 51 CMEs (4.4-159 Mb in size) in 16 out of 130 patients (12.3%), of which 9 had multiple CMEs. The most frequent events were gains at 3q (n = 6) and 1q (n = 5), both previously associated with leukemia, as well as rearrangements with breakpoint clustering within the major histocompatibility complex locus (P = 7.3 × 10-9). Compared with 15 743 age-matched population controls, FA patients had a 126 to 140 times higher risk of detectable CMEs in blood (P < 2.2 × 10-16). Prevalent and incident hematologic and solid cancers were more common in CME carriers (odds ratio [OR] = 11.6, 95% confidence interval [CI] = 3.4-39.3, P = 2.8 × 10-5), leading to poorer prognosis. The age-adjusted hazard risk (HR) of having cancer was almost 5 times higher in FA individuals with CMEs than in those without CMEs. Regarding survival, the HR of dying was 4 times higher in FA individuals having CMEs (HR = 4.0, 95% CI = 2.0-7.9, P = 5.7 × 10-5). Therefore, our data suggest that molecular karyotyping with SNP arrays in easy-to-obtain blood samples could be used for better monitoring of bone marrow clonal events, cancer risk, and overall survival of FA patients.
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239
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Replication Fork Protection Factors Controlling R-Loop Bypass and Suppression. Genes (Basel) 2017; 8:genes8010033. [PMID: 28098815 PMCID: PMC5295027 DOI: 10.3390/genes8010033] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/02/2017] [Accepted: 01/09/2017] [Indexed: 12/17/2022] Open
Abstract
Replication–transcription conflicts have been a well-studied source of genome instability for many years and have frequently been linked to defects in RNA processing. However, recent characterization of replication fork-associated proteins has revealed that defects in fork protection can directly or indirectly stabilize R-loop structures in the genome and promote transcription–replication conflicts that lead to genome instability. Defects in essential DNA replication-associated activities like topoisomerase, or the minichromosome maintenance (MCM) helicase complex, as well as fork-associated protection factors like the Fanconi anemia pathway, both appear to mitigate transcription–replication conflicts. Here, we will highlight recent advances that support the concept that normal and robust replisome function itself is a key component of mitigating R-loop coupled genome instability.
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240
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Brosh RM, Bellani M, Liu Y, Seidman MM. Fanconi Anemia: A DNA repair disorder characterized by accelerated decline of the hematopoietic stem cell compartment and other features of aging. Ageing Res Rev 2017; 33:67-75. [PMID: 27223997 DOI: 10.1016/j.arr.2016.05.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/06/2016] [Accepted: 05/13/2016] [Indexed: 01/05/2023]
Abstract
Fanconi Anemia (FA) is a rare autosomal genetic disorder characterized by progressive bone marrow failure (BMF), endocrine dysfunction, cancer, and other clinical features commonly associated with normal aging. The anemia stems directly from an accelerated decline of the hematopoietic stem cell compartment. Although FA is a complex heterogeneous disease linked to mutations in 19 currently identified genes, there has been much progress in understanding the molecular pathology involved. FA is broadly considered a DNA repair disorder and the FA gene products, together with other DNA repair factors, have been implicated in interstrand cross-link (ICL) repair. However, in addition to the defective DNA damage response, altered epigenetic regulation, and telomere defects, FA is also marked by elevated levels of inflammatory mediators in circulation, a hallmark of faster decline in not only other hereditary aging disorders but also normal aging. In this review, we offer a perspective of FA as a monogenic accelerated aging disorder, citing the latest evidence for its multi-factorial deficiencies underlying its unique clinical and cellular features.
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241
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Roles of human POLD1 and POLD3 in genome stability. Sci Rep 2016; 6:38873. [PMID: 27974823 PMCID: PMC5156928 DOI: 10.1038/srep38873] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/16/2016] [Indexed: 12/11/2022] Open
Abstract
DNA replication is essential for cellular proliferation. If improperly controlled it can constitute a major source of genome instability, frequently associated with cancer and aging. POLD1 is the catalytic subunit and POLD3 is an accessory subunit of the replicative Pol δ polymerase, which also functions in DNA repair, as well as the translesion synthesis polymerase Pol ζ, whose catalytic subunit is REV3L. In cells depleted of POLD1 or POLD3 we found a differential but general increase in genome instability as manifested by DNA breaks, S-phase progression impairment and chromosome abnormalities. Importantly, we showed that both proteins are needed to maintain the proper amount of active replication origins and that POLD3-depletion causes anaphase bridges accumulation. In addition, POLD3-associated DNA damage showed to be dependent on RNA-DNA hybrids pointing toward an additional and specific role of this subunit in genome stability. Interestingly, a similar increase in RNA-DNA hybrids-dependent genome instability was observed in REV3L-depleted cells. Our findings demonstrate a key role of POLD1 and POLD3 in genome stability and S-phase progression revealing RNA-DNA hybrids-dependent effects for POLD3 that might be partly due to its Pol ζ interaction.
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242
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Vuono EA, Mukherjee A, Vierra DA, Adroved MM, Hodson C, Deans AJ, Howlett NG. The PTEN phosphatase functions cooperatively with the Fanconi anemia proteins in DNA crosslink repair. Sci Rep 2016; 6:36439. [PMID: 27819275 PMCID: PMC5098254 DOI: 10.1038/srep36439] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 10/17/2016] [Indexed: 11/13/2022] Open
Abstract
Fanconi anemia (FA) is a genetic disease characterized by bone marrow failure and increased cancer risk. The FA proteins function primarily in DNA interstrand crosslink (ICL) repair. Here, we have examined the role of the PTEN phosphatase in this process. We have established that PTEN-deficient cells, like FA cells, exhibit increased cytotoxicity, chromosome structural aberrations, and error-prone mutagenic DNA repair following exposure to ICL-inducing agents. The increased ICL sensitivity of PTEN-deficient cells is caused, in part, by elevated PLK1 kinase-mediated phosphorylation of FANCM, constitutive FANCM polyubiquitination and degradation, and the consequent inefficient assembly of the FA core complex, FANCD2, and FANCI into DNA repair foci. We also establish that PTEN function in ICL repair is dependent on its protein phosphatase activity and ability to be SUMOylated, yet is independent of its lipid phosphatase activity. Finally, via epistasis analysis, we demonstrate that PTEN and FANCD2 function cooperatively in ICL repair.
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Affiliation(s)
- Elizabeth A. Vuono
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Ananda Mukherjee
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, Grand Rapids, Michigan, USA
| | - David A. Vierra
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Morganne M. Adroved
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
| | - Charlotte Hodson
- Genome Stability Unit, St. Vincent’s Institute, Fitzroy, VIC 3065, Australia
| | - Andrew J. Deans
- Genome Stability Unit, St. Vincent’s Institute, Fitzroy, VIC 3065, Australia
- Department of Medicine, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Niall G. Howlett
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, USA
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243
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Oestergaard VH, Lisby M. Transcription-replication conflicts at chromosomal fragile sites-consequences in M phase and beyond. Chromosoma 2016; 126:213-222. [PMID: 27796495 DOI: 10.1007/s00412-016-0617-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 10/10/2016] [Accepted: 10/17/2016] [Indexed: 12/29/2022]
Abstract
Collision between the molecular machineries responsible for transcription and replication is an important source of genome instability. Certain transcribed regions known as chromosomal fragile sites are particularly prone to recombine and mutate in a manner that correlates with specific transcription and replication patterns. At the same time, these chromosomal fragile sites engage in aberrant DNA structures in mitosis. Here, we discuss the mechanistic details of transcription-replication conflicts including putative scenarios for R-loop-induced replication inhibition to understand how transcription-replication conflicts transition from S phase into various aberrant DNA structures in mitosis.
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Affiliation(s)
- Vibe H Oestergaard
- Department of Biology, University of Copenhagen, Ole Maaloees Vej 5, DK-2200, Copenhagen N, Denmark.
| | - Michael Lisby
- Department of Biology, University of Copenhagen, Ole Maaloees Vej 5, DK-2200, Copenhagen N, Denmark.
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244
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Fradet-Turcotte A, Sitz J, Grapton D, Orthwein A. BRCA2 functions: from DNA repair to replication fork stabilization. Endocr Relat Cancer 2016; 23:T1-T17. [PMID: 27530658 DOI: 10.1530/erc-16-0297] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 08/16/2016] [Indexed: 12/12/2022]
Abstract
Maintaining genomic integrity is essential to preserve normal cellular physiology and to prevent the emergence of several human pathologies including cancer. The breast cancer susceptibility gene 2 (BRCA2, also known as the Fanconi anemia (FA) complementation group D1 (FANCD1)) is a potent tumor suppressor that has been extensively studied in DNA double-stranded break (DSB) repair by homologous recombination (HR). However, BRCA2 participates in numerous other processes central to maintaining genome stability, including DNA replication, telomere homeostasis and cell cycle progression. Consequently, inherited mutations in BRCA2 are associated with an increased risk of breast, ovarian and pancreatic cancers. Furthermore, bi-allelic mutations in BRCA2 are linked to FA, a rare chromosome instability syndrome characterized by aplastic anemia in children as well as susceptibility to leukemia and cancer. Here, we discuss the recent developments underlying the functions of BRCA2 in the maintenance of genomic integrity. The current model places BRCA2 as a central regulator of genome stability by repairing DSBs and limiting replication stress. These findings have direct implications for the development of novel anticancer therapeutic approaches.
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Affiliation(s)
- Amélie Fradet-Turcotte
- Laval University Cancer Research CenterCHU de Québec Research Center - Université Laval, Hôtel-Dieu de Québec, Oncology Axis, Quebec City, Canada
| | - Justine Sitz
- Laval University Cancer Research CenterCHU de Québec Research Center - Université Laval, Hôtel-Dieu de Québec, Oncology Axis, Quebec City, Canada
| | - Damien Grapton
- Lady Davis Institute for Medical ResearchSegal Cancer Centre, Jewish General Hospital, Montreal, Canada
| | - Alexandre Orthwein
- Lady Davis Institute for Medical ResearchSegal Cancer Centre, Jewish General Hospital, Montreal, Canada Department of OncologyMcGill University, Montreal, Canada
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245
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Katsuki Y, Takata M. Defects in homologous recombination repair behind the human diseases: FA and HBOC. Endocr Relat Cancer 2016; 23:T19-37. [PMID: 27550963 DOI: 10.1530/erc-16-0221] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 12/25/2022]
Abstract
Hereditary breast and ovarian cancer (HBOC) syndrome and a rare childhood disorder Fanconi anemia (FA) are caused by homologous recombination (HR) defects, and some of the causative genes overlap. Recent studies in this field have led to the exciting development of PARP inhibitors as novel cancer therapeutics and have clarified important mechanisms underlying genome instability and tumor suppression in HR-defective disorders. In this review, we provide an overview of the basic molecular mechanisms governing HR and DNA crosslink repair, highlighting BRCA2, and the intriguing relationship between HBOC and FA.
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Affiliation(s)
- Yoko Katsuki
- Laboratory of DNA Damage SignalingDepartment of Late Effects Studies, Radiation Biology Center, Kyoto University, Yoshidakonoecho, Sakyo-ku, Kyoto, Japan
| | - Minoru Takata
- Laboratory of DNA Damage SignalingDepartment of Late Effects Studies, Radiation Biology Center, Kyoto University, Yoshidakonoecho, Sakyo-ku, Kyoto, Japan
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246
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Richard P, Manley JL. R Loops and Links to Human Disease. J Mol Biol 2016; 429:3168-3180. [PMID: 27600412 DOI: 10.1016/j.jmb.2016.08.031] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 08/26/2016] [Accepted: 08/31/2016] [Indexed: 12/13/2022]
Abstract
Aberrant R-loop structures are increasingly being realized as an important contributor to human disease. R loops, which are mainly co-transcriptional, abundant RNA/DNA hybrids, form naturally and can indeed be beneficial for transcription regulation at certain loci. However, their unwanted persistence elsewhere or in particular situations can lead to DNA double-strand breaks, chromosome rearrangements, and hypermutation, which are all sources of genomic instability. Mutations in genes involved in R-loop resolution or mutations leading to R-loop formation at specific genes affect the normal physiology of the cell. We discuss here the examples of diseases for which a link with R loops has been described, as well as how disease-causing mutations might participate in the development and/or progression of diseases that include repeat-associated conditions, other neurological disorders, and cancers.
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Affiliation(s)
- Patricia Richard
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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247
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Lopez-Martinez D, Liang CC, Cohn MA. Cellular response to DNA interstrand crosslinks: the Fanconi anemia pathway. Cell Mol Life Sci 2016; 73:3097-114. [PMID: 27094386 PMCID: PMC4951507 DOI: 10.1007/s00018-016-2218-x] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 04/04/2016] [Accepted: 04/05/2016] [Indexed: 12/22/2022]
Abstract
Interstrand crosslinks (ICLs) are a highly toxic form of DNA damage. ICLs can interfere with vital biological processes requiring separation of the two DNA strands, such as replication and transcription. If ICLs are left unrepaired, it can lead to mutations, chromosome breakage and mitotic catastrophe. The Fanconi anemia (FA) pathway can repair this type of DNA lesion, ensuring genomic stability. In this review, we will provide an overview of the cellular response to ICLs. First, we will discuss the origin of ICLs, comparing various endogenous and exogenous sources. Second, we will describe FA proteins as well as FA-related proteins involved in ICL repair, and the post-translational modifications that regulate these proteins. Finally, we will review the process of how ICLs are repaired by both replication-dependent and replication-independent mechanisms.
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Affiliation(s)
- David Lopez-Martinez
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Chih-Chao Liang
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Martin A Cohn
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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248
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Canonical DNA Repair Pathways Influence R-Loop-Driven Genome Instability. J Mol Biol 2016; 429:3132-3138. [PMID: 27452366 DOI: 10.1016/j.jmb.2016.07.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/05/2016] [Accepted: 07/12/2016] [Indexed: 12/22/2022]
Abstract
DNA repair defects create cancer predisposition in humans by fostering a higher rate of mutations. While DNA repair is quite well characterized, recent studies have identified previously unrecognized relationships between DNA repair and R-loop-mediated genome instability. R-loops are three-stranded nucleic acid structures in which RNA binds to genomic DNA to displace a loop of single-stranded DNA. Mutations in homologous recombination, nucleotide excision repair, crosslink repair, and DNA damage checkpoints have all now been linked to formation and function of transcription-coupled R-loops. This perspective will summarize recent literature linking DNA repair to R-loop-mediated genomic instability and discuss how R-loops may contribute to mutagenesis in DNA-repair-deficient cancers.
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249
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García-Muse T, Aguilera A. Transcription–replication conflicts: how they occur and how they are resolved. Nat Rev Mol Cell Biol 2016; 17:553-63. [DOI: 10.1038/nrm.2016.88] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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250
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Al-Hadid Q, Yang Y. R-loop: an emerging regulator of chromatin dynamics. Acta Biochim Biophys Sin (Shanghai) 2016; 48:623-31. [PMID: 27252122 DOI: 10.1093/abbs/gmw052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/29/2016] [Indexed: 12/27/2022] Open
Abstract
The dynamic structure of chromatin, which exists in two conformational states: heterochromatin and euchromatin, alters the accessibility of the DNA to regulatory factors during transcription, replication, recombination, and DNA damage repair. Chemical modifications of histones and DNA, as well as adenosine triphospahate-dependent nucleosome remodeling, have been the major focus of research on chromatin dynamics over the past two decades. However, recent studies using a DNA-RNA hybrid-specific antibody and next-generation sequencing approaches have revealed that the formation of R-loops, one of the most common non-canonical DNA structures, is an emerging regulator of chromatin states. This review focuses on recent insights into the interplay between R-loop formation and the epigenetic modifications of chromatin in normal and disease states.
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Affiliation(s)
- Qais Al-Hadid
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Cancer Center, Duarte, CA 91010, USA
| | - Yanzhong Yang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Cancer Center, Duarte, CA 91010, USA
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