1
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Luna R, Gómez-González B, Aguilera A. RNA biogenesis and RNA metabolism factors as R-loop suppressors: a hidden role in genome integrity. Genes Dev 2024; 38:504-527. [PMID: 38986581 PMCID: PMC11293400 DOI: 10.1101/gad.351853.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Genome integrity relies on the accuracy of DNA metabolism, but as appreciated for more than four decades, transcription enhances mutation and recombination frequencies. More recent research provided evidence for a previously unforeseen link between RNA and DNA metabolism, which is often related to the accumulation of DNA-RNA hybrids and R-loops. In addition to physiological roles, R-loops interfere with DNA replication and repair, providing a molecular scenario for the origin of genome instability. Here, we review current knowledge on the multiple RNA factors that prevent or resolve R-loops and consequent transcription-replication conflicts and thus act as modulators of genome dynamics.
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Affiliation(s)
- Rosa Luna
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Belén Gómez-González
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain;
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
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2
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Lafuente-Barquero J, Svejstrup JQ, Luna R, Aguilera A. Expression of human RECQL5 in Saccharomyces cerevisiae causes transcription defects and transcription-associated genome instability. Mol Genet Genomics 2024; 299:59. [PMID: 38796829 PMCID: PMC11128410 DOI: 10.1007/s00438-024-02152-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 05/13/2024] [Indexed: 05/29/2024]
Abstract
RECQL5 is a member of the conserved RecQ family of DNA helicases involved in the maintenance of genome stability that is specifically found in higher eukaryotes and associates with the elongating RNA polymerase II. To expand our understanding of its function we expressed human RECQL5 in the yeast Saccharomyces cerevisiae, which does not have a RECQL5 ortholog. We found that RECQL5 expression leads to cell growth inhibition, increased genotoxic sensitivity and transcription-associated hyperrecombination. Chromatin immunoprecipitation and transcriptomic analysis of yeast cells expressing human RECQL5 shows that this is recruited to transcribed genes and although it causes only a weak impact on gene expression, in particular at G + C-rich genes, it leads to a transcription termination defect detected as readthrough transcription. The data indicate that the interaction between RNAPII and RECQL5 is conserved from yeast to humans. Unexpectedly, however, the RECQL5-ID mutant, previously shown to have reduced the association with RNAPII in vitro, associates with the transcribing polymerase in cells. As a result, expression of RECQL5-ID leads to similar although weaker phenotypes than wild-type RECQL5 that could be transcription-mediated. Altogether, the data suggests that RECQL5 has the intrinsic ability to function in transcription-dependent and independent genome dynamics in S. cerevisiae.
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Affiliation(s)
- Juan Lafuente-Barquero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012, Seville, Spain
| | - Jesper Q Svejstrup
- University of Copenhagen, Copenhagen, Denmark
- Francis Crick Institute, London, UK
| | - Rosa Luna
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain.
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012, Seville, Spain.
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012, Seville, Spain
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3
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Hidmi O, Oster S, Monin J, Aqeilan RI. TOP1 and R-loops facilitate transcriptional DSBs at hypertranscribed cancer driver genes. iScience 2024; 27:109082. [PMID: 38375218 PMCID: PMC10875566 DOI: 10.1016/j.isci.2024.109082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/26/2023] [Accepted: 01/28/2024] [Indexed: 02/21/2024] Open
Abstract
DNA double-stranded breaks (DSBs) pose a significant threat to genomic integrity, and their generation during essential cellular processes like transcription remains poorly understood. In this study, we employ several techniques to map DSBs, R-loops, and topoisomerase 1 cleavage complex (TOP1cc) to comprehensively investigate the interplay between transcription, DSBs, topoisomerase 1 (TOP1), and R-loops. Our findings reveal the presence of DSBs at highly expressed genes enriched with TOP1 and R-loops. Remarkably, transcription-associated DSBs at these loci are significantly reduced upon depletion of R-loops and TOP1, uncovering the pivotal roles of TOP1 and R-loops in transcriptional DSB formation. By elucidating the intricate interplay between TOP1cc trapping, R-loops, and DSBs, our study provides insights into the mechanisms underlying transcription-associated genomic instability. Moreover, we establish a link between transcriptional DSBs and early molecular changes driving cancer development, highlighting the distinct etiology and molecular characteristics of driver mutations compared to passenger mutations.
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Affiliation(s)
- Osama Hidmi
- The Concern Foundation Laboratories, The Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research-IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sara Oster
- The Concern Foundation Laboratories, The Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research-IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jonathan Monin
- The Concern Foundation Laboratories, The Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research-IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rami I. Aqeilan
- The Concern Foundation Laboratories, The Lautenberg Center for Immunology and Cancer Research, Department of Immunology and Cancer Research-IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- Cyprus Cancer Research Institute (CCRI), Nicosia, Cyprus
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4
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Gu L, Li M, Li CM, Haratipour P, Lingeman R, Jossart J, Gutova M, Flores L, Hyde C, Kenjić N, Li H, Chung V, Li H, Lomenick B, Von Hoff DD, Synold TW, Aboody KS, Liu Y, Horne D, Hickey RJ, Perry JJP, Malkas LH. Small molecule targeting of transcription-replication conflict for selective chemotherapy. Cell Chem Biol 2023; 30:1235-1247.e6. [PMID: 37531956 PMCID: PMC10592352 DOI: 10.1016/j.chembiol.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 02/12/2023] [Accepted: 07/10/2023] [Indexed: 08/04/2023]
Abstract
Targeting transcription replication conflicts, a major source of endogenous DNA double-stranded breaks and genomic instability could have important anticancer therapeutic implications. Proliferating cell nuclear antigen (PCNA) is critical to DNA replication and repair processes. Through a rational drug design approach, we identified a small molecule PCNA inhibitor, AOH1996, which selectively kills cancer cells. AOH1996 enhances the interaction between PCNA and the largest subunit of RNA polymerase II, RPB1, and dissociates PCNA from actively transcribed chromatin regions, while inducing DNA double-stranded breaks in a transcription-dependent manner. Attenuation of RPB1 interaction with PCNA, by a point mutation in RPB1's PCNA-binding region, confers resistance to AOH1996. Orally administrable and metabolically stable, AOH1996 suppresses tumor growth as a monotherapy or as a combination treatment but causes no discernable side effects. Inhibitors of transcription replication conflict resolution may provide a new and unique therapeutic avenue for exploiting this cancer-selective vulnerability.
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Affiliation(s)
- Long Gu
- Department of Molecular Diagnostics & Experimental Therapeutics, Beckman Research Institute of City of Hope, Duarte, CA, USA.
| | - Min Li
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Caroline M Li
- Department of Molecular Diagnostics & Experimental Therapeutics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Pouya Haratipour
- Department of Cancer Biology & Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Robert Lingeman
- Department of Molecular Diagnostics & Experimental Therapeutics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Jennifer Jossart
- Department of Molecular Diagnostics & Experimental Therapeutics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Margarita Gutova
- Department of Developmental & Stem Cell Biology, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Linda Flores
- Department of Developmental & Stem Cell Biology, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Caitlyn Hyde
- Department of Developmental & Stem Cell Biology, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Nikola Kenjić
- Department of Biochemistry, University of California Riverside, Riverside, CA, USA
| | - Haiqing Li
- Department of Genomics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Vincent Chung
- Department of Medical Oncology, City of Hope, Duarte, CA, USA
| | - Hongzhi Li
- Department of Bioinformatics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Brett Lomenick
- Proteome Exploration Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Daniel D Von Hoff
- Clinical Translational Research Division, Translational Genomics Research Institute, 445N 5th Street, Phoenix, AZ 85004, USA
| | - Timothy W Synold
- Department of Medical Oncology and Therapeutics Research, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Karen S Aboody
- Department of Developmental & Stem Cell Biology, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - David Horne
- Department of Cancer Biology & Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Robert J Hickey
- Department of Cancer Biology & Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - J Jefferson P Perry
- Department of Molecular Diagnostics & Experimental Therapeutics, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Linda H Malkas
- Department of Molecular Diagnostics & Experimental Therapeutics, Beckman Research Institute of City of Hope, Duarte, CA, USA
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5
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Mo C, Shiozaki Y, Omabe K, Liu Y. Understanding the Human RECQ5 Helicase-Connecting the Dots from DNA to Clinics. Cells 2023; 12:2037. [PMID: 37626846 PMCID: PMC10453775 DOI: 10.3390/cells12162037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/03/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023] Open
Abstract
RECQ5, a member of the conserved RECQ helicase family, is the sole human RECQ homolog that has not been linked to a hereditary developmental syndrome. Nonetheless, dysregulation of RECQ5 has emerged as a significant clinical concern, being linked to cancer predisposition, cardiovascular disease, and inflammation. In cells, RECQ5 assumes a crucial role in the regulation of DNA repair pathways, particularly in the repair of DNA double-strand breaks and inter-strand DNA crosslinks. Moreover, RECQ5 exhibits a capacity to modulate gene expression by interacting with transcription machineries and their co-regulatory proteins, thus safeguarding against transcription-induced DNA damage. This review aims to provide an overview of the multifaceted functions of RECQ5 and its implications in maintaining genomic stability. We will discuss the potential effects of clinical variants of RECQ5 on its cellular functions and their underlying mechanisms in the pathogenesis of cancer and cardiovascular disease. We will review the impact of RECQ5 variants in the field of pharmacogenomics, specifically their influence on drug responses, which may pave the way for novel therapeutic interventions targeting RECQ5 in human diseases.
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Affiliation(s)
| | | | | | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010-3000, USA
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6
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Saha S, Pommier Y. R-loops, type I topoisomerases and cancer. NAR Cancer 2023; 5:zcad013. [PMID: 37600974 PMCID: PMC9984992 DOI: 10.1093/narcan/zcad013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/18/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
R-loops are abundant and dynamic structures ubiquitously present in human cells both in the nuclear and mitochondrial genomes. They form in cis in the wake of transcription complexes and in trans apart from transcription complexes. In this review, we focus on the relationship between R-loops and topoisomerases, and cancer genomics and therapies. We summarize the topological parameters associated with the formation and resolution of R-loops, which absorb and release high levels of genomic negative supercoiling (Sc-). We review the deleterious consequences of excessive R-loops and rationalize how human type IA (TOP3B) and type IB (TOP1) topoisomerases regulate and resolve R-loops in coordination with helicase and RNase H enzymes. We also review the drugs (topoisomerase inhibitors, splicing inhibitors, G4 stabilizing ligands) and cancer predisposing genes (BRCA1/2, transcription, and splicing genes) known to induce R-loops, and whether stabilizing R-loops and thereby inducing genomic damage can be viewed as a strategy for cancer treatment.
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Affiliation(s)
- Sourav Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Yves Pommier
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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7
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The BRCA1 BRCT promotes antisense RNA production and double-stranded RNA formation to suppress ribosomal R-loops. Proc Natl Acad Sci U S A 2022; 119:e2217542119. [PMID: 36490315 PMCID: PMC9897471 DOI: 10.1073/pnas.2217542119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
R-loops, or RNA:DNA hybrids, can induce DNA damage, which requires DNA repair factors including breast cancer type 1 susceptibility protein (BRCA1) to restore genomic integrity. To date, several pathogenic mutations have been found within the tandem BRCA1 carboxyl-terminal (BRCT) domains that mediate BRCA1 interactions with proteins and DNA in response to DNA damage. Here, we describe a nonrepair role of BRCA1 BRCT in suppressing ribosomal R-loops via two mechanisms. Through its RNA binding and annealing activities, BRCA1 BRCT facilitates the formation of double-stranded RNA between ribosomal RNA (rRNA) and antisense-rRNA (as-rRNA), hereby minimizing rRNA hybridization to ribosomal DNA to form R-loops. BRCA1 BRCT also promotes RNA polymerase I-dependent transcription of as-rRNA to enhance double-stranded rRNA (ds-rRNA) formation. In addition, BRCA1 BRCT-mediated as-rRNA production restricts rRNA maturation in unperturbed cells. Hence, impairing as-rRNA transcription and ds-rRNA formation due to BRCA1 BRCT deficiency deregulates rRNA processing and increases ribosomal R-loops and DNA breaks. Our results link ribosomal biogenesis dysfunction to BRCA1-associated genomic instability.
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8
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Zhou J, Zhang W, Sun Q. R-loop: The new genome regulatory element in plants. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2022; 64:2275-2289. [PMID: 36223078 DOI: 10.1111/jipb.13383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
An R-loop is a three-stranded chromatin structure that consists of a displaced single strand of DNA and an RNA:DNA hybrid duplex, which was thought to be a rare by-product of transcription. However, recent genome-wide data have shown that R-loops are widespread and pervasive in a variety of genomes, and a growing body of experimental evidence indicates that R-loops have both beneficial and harmful effects on an organism. To maximize benefit and avoid harm, organisms have evolved several means by which they tightly regulate R-loop levels. Here, we summarize our current understanding of the biogenesis and effects of R-loops, the mechanisms that regulate them, and methods of R-loop profiling, reviewing recent research advances on R-loops in plants. Furthermore, we provide perspectives on future research directions for R-loop biology in plants, which might lead to a more comprehensive understanding of R-loop functions in plant genome regulation and contribute to future agricultural improvements.
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Affiliation(s)
- Jincong Zhou
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Weifeng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
| | - Qianwen Sun
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Center for Life Sciences, Beijing, 100084, China
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9
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Sun Y, Nitiss JL, Pommier Y. SUMO: A Swiss Army Knife for Eukaryotic Topoisomerases. Front Mol Biosci 2022; 9:871161. [PMID: 35463961 PMCID: PMC9019546 DOI: 10.3389/fmolb.2022.871161] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 03/11/2022] [Indexed: 01/03/2023] Open
Abstract
Topoisomerases play crucial roles in DNA metabolism that include replication, transcription, recombination, and chromatin structure by manipulating DNA structures arising in double-stranded DNA. These proteins play key enzymatic roles in a variety of cellular processes and are also likely to play structural roles. Topoisomerases allow topological transformations by introducing transient breaks in DNA by a transesterification reaction between a tyrosine residue of the enzyme and DNA. The cleavage reaction leads to a unique enzyme intermediate that allows cutting DNA while minimizing the potential for damage-induced genetic changes. Nonetheless, topoisomerase-mediated cleavage has the potential for inducing genome instability if the enzyme-mediated DNA resealing is impaired. Regulation of topoisomerase functions is accomplished by post-translational modifications including phosphorylation, polyADP-ribosylation, ubiquitylation, and SUMOylation. These modifications modulate enzyme activity and likely play key roles in determining sites of enzyme action and enzyme stability. Topoisomerase-mediated DNA cleavage and rejoining are affected by a variety of conditions including the action of small molecules, topoisomerase mutations, and DNA structural forms which permit the conversion of the short-lived cleavage intermediate to persistent topoisomerase DNA-protein crosslink (TOP-DPC). Recognition and processing of TOP-DPCs utilizes many of the same post-translational modifications that regulate enzyme activity. This review focuses on SUMOylation of topoisomerases, which has been demonstrated to be a key modification of both type I and type II topoisomerases. Special emphasis is placed on recent studies that indicate how SUMOylation regulates topoisomerase function in unperturbed cells and the unique roles that SUMOylation plays in repairing damage arising from topoisomerase malfunction.
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Affiliation(s)
- Yilun Sun
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, United States
| | - John L. Nitiss
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois, Rockford, IL, United States
| | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, United States
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10
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Marabitti V, Valenzisi P, Lillo G, Malacaria E, Palermo V, Pichierri P, Franchitto A. R-Loop-Associated Genomic Instability and Implication of WRN and WRNIP1. Int J Mol Sci 2022; 23:ijms23031547. [PMID: 35163467 PMCID: PMC8836129 DOI: 10.3390/ijms23031547] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 02/05/2023] Open
Abstract
Maintenance of genome stability is crucial for cell survival and relies on accurate DNA replication. However, replication fork progression is under constant attack from different exogenous and endogenous factors that can give rise to replication stress, a source of genomic instability and a notable hallmark of pre-cancerous and cancerous cells. Notably, one of the major natural threats for DNA replication is transcription. Encounters or conflicts between replication and transcription are unavoidable, as they compete for the same DNA template, so that collisions occur quite frequently. The main harmful transcription-associated structures are R-loops. These are DNA structures consisting of a DNA–RNA hybrid and a displaced single-stranded DNA, which play important physiological roles. However, if their homeostasis is altered, they become a potent source of replication stress and genome instability giving rise to several human diseases, including cancer. To combat the deleterious consequences of pathological R-loop persistence, cells have evolved multiple mechanisms, and an ever growing number of replication fork protection factors have been implicated in preventing/removing these harmful structures; however, many others are perhaps still unknown. In this review, we report the current knowledge on how aberrant R-loops affect genome integrity and how they are handled, and we discuss our recent findings on the role played by two fork protection factors, the Werner syndrome protein (WRN) and the Werner helicase-interacting protein 1 (WRNIP1) in response to R-loop-induced genome instability.
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11
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Exploring the multifunctionality of SR proteins. Biochem Soc Trans 2021; 50:187-198. [PMID: 34940860 PMCID: PMC9022966 DOI: 10.1042/bst20210325] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 12/31/2022]
Abstract
Members of the arginine–serine-rich protein family (SR proteins) are multifunctional RNA-binding proteins that have emerged as key determinants for mRNP formation, identity and fate. They bind to pre-mRNAs early during transcription in the nucleus and accompany bound transcripts until they are translated or degraded in the cytoplasm. SR proteins are mostly known for their essential roles in constitutive splicing and as regulators of alternative splicing. However, many additional activities of individual SR proteins, beyond splicing, have been reported in recent years. We will summarize the different functions of SR proteins and discuss how multifunctionality can be achieved. We will also highlight the difficulties of studying highly versatile SR proteins and propose approaches to disentangle their activities, which is transferrable to other multifunctional RBPs.
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12
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Lee SY, Kim JJ, Miller KM. Bromodomain proteins: protectors against endogenous DNA damage and facilitators of genome integrity. Exp Mol Med 2021; 53:1268-1277. [PMID: 34548613 PMCID: PMC8492697 DOI: 10.1038/s12276-021-00673-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/13/2021] [Indexed: 12/11/2022] Open
Abstract
Endogenous DNA damage is a major contributor to mutations, which are drivers of cancer development. Bromodomain (BRD) proteins are well-established participants in chromatin-based DNA damage response (DDR) pathways, which maintain genome integrity from cell-intrinsic and extrinsic DNA-damaging sources. BRD proteins are most well-studied as regulators of transcription, but emerging evidence has revealed their importance in other DNA-templated processes, including DNA repair and replication. How BRD proteins mechanistically protect cells from endogenous DNA damage through their participation in these pathways remains an active area of investigation. Here, we review several recent studies establishing BRD proteins as key influencers of endogenous DNA damage, including DNA–RNA hybrid (R-loops) formation during transcription and participation in replication stress responses. As endogenous DNA damage is known to contribute to several human diseases, including neurodegeneration, immunodeficiencies, cancer, and aging, the ability of BRD proteins to suppress DNA damage and mutations is likely to provide new insights into the involvement of BRD proteins in these diseases. Although many studies have focused on BRD proteins in transcription, evidence indicates that BRD proteins have emergent functions in DNA repair and genome stability and are participants in the etiology and treatment of diseases involving endogenous DNA damage. Bromodomain (BRD) proteins, known to regulate gene expression, switching particular genes on and off, also play key roles in repairing DNA damage, and studying them may help identify treatments for various diseases, including cancer. DNA damage can occur during normal cellular metabolism, for example, during copying DNA and gene expression. DNA damage is implicated in tumor formation as well as in neurodegeneration, immunodeficiency, and aging. Seo Yun Lee and colleagues at The University of Texas at Austin, USA, have reviewed new results showing how BRD proteins function in repairing DNA damage. They report that when DNA is damaged during copying in BRD-deficient cells, tumors can result. They also report that defects in BRD proteins are often present in cancers. Studying how BRD proteins function in both healthy and diseased cells could help to identify new therapies.
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Affiliation(s)
- Seo Yun Lee
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA
| | - Jae Jin Kim
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA. .,Department of Life Science and Multidisciplinary Genome Institute, Hallym University, Chuncheon, Korea.
| | - Kyle M Miller
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, USA. .,Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, TX, USA.
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13
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Transcription/Replication Conflicts in Tumorigenesis and Their Potential Role as Novel Therapeutic Targets in Multiple Myeloma. Cancers (Basel) 2021; 13:cancers13153755. [PMID: 34359660 PMCID: PMC8345052 DOI: 10.3390/cancers13153755] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/13/2021] [Accepted: 07/22/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Multiple myeloma is a hematologic cancer characterized by the accumulation of malignant plasma cells in the bone marrow. It remains a mostly incurable disease due to the inability to overcome refractory disease and drug-resistant relapse. Oncogenic transformation of PC in multiple myeloma is thought to occur within the secondary lymphoid organs. However, the precise molecular events leading to myelomagenesis remain obscure. Here, we identified genes involved in the prevention and the resolution of conflicts between the replication and transcription significantly overexpressed during the plasma cell differentiation process and in multiple myeloma cells. We discussed the potential role of these factors in myelomagenesis and myeloma biology. The specific targeting of these factors might constitute a new therapeutic strategy in multiple myeloma. Abstract Plasma cells (PCs) have an essential role in humoral immune response by secretion of antibodies, and represent the final stage of B lymphocytes differentiation. During this differentiation, the pre-plasmablastic stage is characterized by highly proliferative cells that start to secrete immunoglobulins (Igs). Thus, replication and transcription must be tightly regulated in these cells to avoid transcription/replication conflicts (TRCs), which could increase replication stress and lead to genomic instability. In this review, we analyzed expression of genes involved in TRCs resolution during B to PC differentiation and identified 41 genes significantly overexpressed in the pre-plasmablastic stage. This illustrates the importance of mechanisms required for adequate processing of TRCs during PCs differentiation. Furthermore, we identified that several of these factors were also found overexpressed in purified PCs from patients with multiple myeloma (MM) compared to normal PCs. Malignant PCs produce high levels of Igs concomitantly with cell cycle deregulation. Therefore, increasing the TRCs occurring in MM cells could represent a potent therapeutic strategy for MM patients. Here, we describe the potential roles of TRCs resolution factors in myelomagenesis and discuss the therapeutic interest of targeting the TRCs resolution machinery in MM.
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14
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Bossaert M, Pipier A, Riou JF, Noirot C, Nguyên LT, Serre RF, Bouchez O, Defrancq E, Calsou P, Britton S, Gomez D. Transcription-associated topoisomerase 2α (TOP2A) activity is a major effector of cytotoxicity induced by G-quadruplex ligands. eLife 2021; 10:65184. [PMID: 34180392 PMCID: PMC8279764 DOI: 10.7554/elife.65184] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 06/16/2021] [Indexed: 12/11/2022] Open
Abstract
G-quadruplexes (G4) are non-canonical DNA structures found in the genome of most species including human. Small molecules stabilizing these structures, called G4 ligands, have been identified and, for some of them, shown to induce cytotoxic DNA double-strand breaks. Through the use of an unbiased genetic approach, we identify here topoisomerase 2α (TOP2A) as a major effector of cytotoxicity induced by two clastogenic G4 ligands, pyridostatin and CX-5461, the latter molecule currently undergoing phase I/II clinical trials in oncology. We show that both TOP2 activity and transcription account for DNA break production following G4 ligand treatments. In contrast, clastogenic activity of these G4 ligands is countered by topoisomerase 1 (TOP1), which limits co-transcriptional G4 formation, and by factors promoting transcriptional elongation. Altogether our results support that clastogenic G4 ligands act as DNA structure-driven TOP2 poisons at transcribed regions bearing G4 structures.
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Affiliation(s)
- Madeleine Bossaert
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Angélique Pipier
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Jean-Francois Riou
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, CNRS, INSERM, Paris, France
| | - Céline Noirot
- INRAE, UR 875, Unité de Mathématique et Informatique Appliquées, Genotoul Bioinfo, Castanet-Tolosan, France
| | - Linh-Trang Nguyên
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | | | - Olivier Bouchez
- INRAE, US 1426, GeT-PlaGe, Genotoul, Castanet-Tolosan, France
| | - Eric Defrancq
- Département de Chimie Moléculaire, UMR CNRS 5250, Université Grenoble Alpes, Grenoble, France
| | - Patrick Calsou
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Sébastien Britton
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
| | - Dennis Gomez
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France.,Equipe Labellisée Ligue Contre le Cancer 2018, Toulouse, France
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15
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Das T, Pal S, Ganguly A. Human RecQ helicases in transcription-associated stress management: bridging the gap between DNA and RNA metabolism. Biol Chem 2021; 402:617-636. [PMID: 33567180 DOI: 10.1515/hsz-2020-0324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 01/24/2021] [Indexed: 12/13/2022]
Abstract
RecQ helicases are a highly conserved class of DNA helicases that play crucial role in almost all DNA metabolic processes including replication, repair and recombination. They are able to unwind a wide variety of complex intermediate DNA structures that may result from cellular DNA transactions and hence assist in maintaining genome integrity. Interestingly, a huge number of recent reports suggest that many of the RecQ family helicases are directly or indirectly involved in regulating transcription and gene expression. On one hand, they can remove complex structures like R-loops, G-quadruplexes or RNA:DNA hybrids formed at the intersection of transcription and replication. On the other hand, emerging evidence suggests that they can also regulate transcription by directly interacting with RNA polymerase or recruiting other protein factors that may regulate transcription. This review summarizes the up to date knowledge on the involvement of three human RecQ family proteins BLM, WRN and RECQL5 in transcription regulation and management of transcription associated stress.
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Affiliation(s)
- Tulika Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur721302, India
| | - Surasree Pal
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur721302, India
| | - Agneyo Ganguly
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur721302, India
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16
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Dhar S, Datta A, Brosh RM. DNA helicases and their roles in cancer. DNA Repair (Amst) 2020; 96:102994. [PMID: 33137625 DOI: 10.1016/j.dnarep.2020.102994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/15/2022]
Abstract
DNA helicases, known for their fundamentally important roles in genomic stability, are high profile players in cancer. Not only are there monogenic helicase disorders with a strong disposition to cancer, it is well appreciated that helicase variants are associated with specific cancers (e.g., breast cancer). Flipping the coin, DNA helicases are frequently overexpressed in cancerous tissues and reduction in helicase gene expression results in reduced proliferation and growth capacity, as well as DNA damage induction and apoptosis of cancer cells. The seminal roles of helicases in the DNA damage and replication stress responses, as well as DNA repair pathways, validate their vital importance in cancer biology and suggest their potential values as targets in anti-cancer therapy. In recent years, many laboratories have characterized the specialized roles of helicase to resolve transcription-replication conflicts, maintain telomeres, mediate cell cycle checkpoints, remodel stalled replication forks, and regulate transcription. In vivo models, particularly mice, have been used to interrogate helicase function and serve as a bridge for preclinical studies that may lead to novel therapeutic approaches. In this review, we will summarize our current knowledge of DNA helicases and their roles in cancer, emphasizing the latest developments.
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Affiliation(s)
- Srijita Dhar
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Arindam Datta
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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17
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Chang CW, Xu X, Li M, Xin D, Ding L, Wang YT, Liu Y. Pathogenic mutations reveal a role of RECQ4 in mitochondrial RNA:DNA hybrid formation and resolution. Sci Rep 2020; 10:17033. [PMID: 33046774 PMCID: PMC7552406 DOI: 10.1038/s41598-020-74095-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 09/21/2020] [Indexed: 11/09/2022] Open
Abstract
The synthesis of mitochondrial DNA (mtDNA) is a complex process that involves the formation and resolution of unusual nucleic acid structures, such as RNA:DNA hybrids. However, little is known about the enzymes that regulate these processes. RECQ4 is a DNA replication factor important for mtDNA maintenance, and here, we unveil a role of human RECQ4 in regulating the formation and resolution of mitochondrial RNA:DNA hybrids. Mitochondrial membrane protein p32 can block mtDNA synthesis by restricting RECQ4 mitochondrial localization via protein–protein interaction. We found that the interaction with p32 was disrupted not only by the previously reported cancer-associated RECQ4 mutation, del(A420-A463), but also by a clinical mutation of the adjacent residue, P466L. Surprisingly, although P466L mutant was present in the mitochondria at greater levels, unlike del(A420-A463) mutant, it failed to enhance mtDNA synthesis due to the accumulation of RNA:DNA hybrids throughout the mtDNA. Biochemical analysis revealed that P466L mutation enhanced RECQ4 annealing activity to generate RNA:DNA hybrids at the same time reduced its unwinding activity to resolve this structure. Hence, P466L mutation led to a reduced efficiency in completing mtDNA synthesis due to unresolved RNA:DNA hybrids across mtDNA.
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Affiliation(s)
- Chou-Wei Chang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Xiaohua Xu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Min Li
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Di Xin
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Lin Ding
- J. Craig Venter Institute, San Diego, CA, 92037, USA
| | - Ya-Ting Wang
- Memorial Sloan Kettering, New York, NY, 10065, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA.
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18
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TRIM28 functions as the SUMO E3 ligase for PCNA in prevention of transcription induced DNA breaks. Proc Natl Acad Sci U S A 2020; 117:23588-23596. [PMID: 32900933 DOI: 10.1073/pnas.2004122117] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
In human cells, the DNA replication factor proliferating cell nuclear antigen (PCNA) can be conjugated to either the small ubiquitinlike modifier SUMO1 or SUMO2, but only SUMO2-conjugated PCNA is induced by transcription to facilitate resolution of transcription-replication conflict (TRC). To date, the SUMO E3 ligase that provides substrate specificity for SUMO2-PCNA conjugation in response to TRC remains unknown. Using a proteomic approach, we identified TRIM28 as the E3 ligase that catalyzes SUMO2-PCNA conjugation. In vitro, TRIM28, together with the RNA polymerase II (RNAPII)-interacting protein RECQ5, promotes SUMO2-PCNA conjugation but inhibits SUMO1-PCNA formation. This activity requires a PCNA-interacting protein (PIP) motif located within the bromodomain of TRIM28. In cells, TRIM28 interaction with PCNA on human chromatin is dependent on both transcription and RECQ5, and SUMO2-PCNA level correlates with TRIM28 expression. As a consequence, TRIM28 depletion led to RNAPII accumulation at TRC sites, and expression of a TRIM28 PIP mutant failed to suppress TRC-induced DNA breaks.
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19
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Luna R, Rondón AG, Pérez-Calero C, Salas-Armenteros I, Aguilera A. The THO Complex as a Paradigm for the Prevention of Cotranscriptional R-Loops. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2020; 84:105-114. [PMID: 32493765 DOI: 10.1101/sqb.2019.84.039594] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Different proteins associate with the nascent RNA and the RNA polymerase (RNAP) to catalyze the transcription cycle and RNA export. If these processes are not properly controlled, the nascent RNA can thread back and hybridize to the DNA template forming R-loops capable of stalling replication, leading to DNA breaks. Given the transcriptional promiscuity of the genome, which leads to large amounts of RNAs from mRNAs to different types of ncRNAs, these can become a major threat to genome integrity if they form R-loops. Consequently, cells have evolved nuclear factors to prevent this phenomenon that includes THO, a conserved eukaryotic complex acting in transcription elongation and RNA processing and export that upon inactivation causes genome instability linked to R-loop accumulation. We revise and discuss here the biological relevance of THO and a number of RNA helicases, including the THO partner UAP56/DDX39B, as a paradigm of the cellular mechanisms of cotranscriptional R-loop prevention.
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Affiliation(s)
- Rosa Luna
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092 Seville, Spain
| | - Ana G Rondón
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092 Seville, Spain
| | - Carmen Pérez-Calero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092 Seville, Spain
| | - Irene Salas-Armenteros
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092 Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092 Seville, Spain
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20
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Zhang LH, Zhang XY, Hu T, Chen XY, Li JJ, Raida M, Sun N, Luo Y, Gao X. The SUMOylated METTL8 Induces R-loop and Tumorigenesis via m3C. iScience 2020; 23:100968. [PMID: 32199293 PMCID: PMC7082549 DOI: 10.1016/j.isci.2020.100968] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/08/2020] [Accepted: 03/03/2020] [Indexed: 01/26/2023] Open
Abstract
R-loops, three-stranded DNA-DNA:RNA hybrid structures, are best known for their deleterious effects on genome stability. The regulatory factors of this fundamental genetic structure remain unclear. Here, we reveal an epigenetic factor that controls R-loop stability. METTL8, a member of the methyltransferase-like protein family that methylates 3-methylcytidine (m3C), is a key factor in the R-loop regulating methyltransferase complex. Biochemical studies show that METTL8 forms a large SUMOylated nuclear RNA-binding protein complex (∼0.8 mega daltons) that contains well-reported R-loop related factors. Genetic ablation of METTL8 results in an overall reduction of R-loops in cells. Interaction assays indicated METTL8 binds to RNAs and is responsible for R-loop stability on selected gene regions. Our results demonstrate that the SUMOylated METTL8 promotes tumorigenesis by affecting genetic organization primarily in, or in close proximity to, the nucleolus and impacts the formation of regulatory R-loops through its methyltransferase activity on m3C. DNA:RNA hybrid structures are regulated by RNA methyltransferase via 3-methylcytidine SUMOylation stabilizes the RNA methyltransferase complex in the nucleus Dysregulation of DNA:RNA hybrids may induce tumorigenesis in mammalian cells
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Affiliation(s)
- Li-Hong Zhang
- Department of Biochemistry and Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Key Laboratory of Cancer Prevention and Intervention of China National Ministry of Education, Hangzhou 310009, China
| | - Xue-Yun Zhang
- Department of Biochemistry and Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Key Laboratory of Cancer Prevention and Intervention of China National Ministry of Education, Hangzhou 310009, China
| | - Tao Hu
- Department of Spine Surgery, Shanghai East Hospital, Tongji University, Shanghai 200092, China
| | - Xin-Yun Chen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Jing-Jia Li
- Department of Biochemistry and Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Key Laboratory of Cancer Prevention and Intervention of China National Ministry of Education, Hangzhou 310009, China
| | - Manfred Raida
- Life Sciences Institute, National University of Singapore, Singapore 117456, Singapore
| | - Ning Sun
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Yan Luo
- Department of Biochemistry and Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Key Laboratory of Cancer Prevention and Intervention of China National Ministry of Education, Hangzhou 310009, China.
| | - Xiang Gao
- Department of Biochemistry and Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Key Laboratory of Cancer Prevention and Intervention of China National Ministry of Education, Hangzhou 310009, China.
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21
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Brosh RM, Matson SW. History of DNA Helicases. Genes (Basel) 2020; 11:genes11030255. [PMID: 32120966 PMCID: PMC7140857 DOI: 10.3390/genes11030255] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 12/13/2022] Open
Abstract
Since the discovery of the DNA double helix, there has been a fascination in understanding the molecular mechanisms and cellular processes that account for: (i) the transmission of genetic information from one generation to the next and (ii) the remarkable stability of the genome. Nucleic acid biologists have endeavored to unravel the mysteries of DNA not only to understand the processes of DNA replication, repair, recombination, and transcription but to also characterize the underlying basis of genetic diseases characterized by chromosomal instability. Perhaps unexpectedly at first, DNA helicases have arisen as a key class of enzymes to study in this latter capacity. From the first discovery of ATP-dependent DNA unwinding enzymes in the mid 1970's to the burgeoning of helicase-dependent pathways found to be prevalent in all kingdoms of life, the story of scientific discovery in helicase research is rich and informative. Over four decades after their discovery, we take this opportunity to provide a history of DNA helicases. No doubt, many chapters are left to be written. Nonetheless, at this juncture we are privileged to share our perspective on the DNA helicase field - where it has been, its current state, and where it is headed.
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Affiliation(s)
- Robert M. Brosh
- Section on DNA Helicases, Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
- Correspondence: (R.M.B.J.); (S.W.M.); Tel.: +1-410-558-8578 (R.M.B.J.); +1-919-962-0005 (S.W.M.)
| | - Steven W. Matson
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Correspondence: (R.M.B.J.); (S.W.M.); Tel.: +1-410-558-8578 (R.M.B.J.); +1-919-962-0005 (S.W.M.)
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22
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Andrs M, Hasanova Z, Oravetzova A, Dobrovolna J, Janscak P. RECQ5: A Mysterious Helicase at the Interface of DNA Replication and Transcription. Genes (Basel) 2020; 11:genes11020232. [PMID: 32098287 PMCID: PMC7073763 DOI: 10.3390/genes11020232] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/14/2020] [Accepted: 02/18/2020] [Indexed: 12/11/2022] Open
Abstract
RECQ5 belongs to the RecQ family of DNA helicases. It is conserved from Drosophila to humans and its deficiency results in genomic instability and cancer susceptibility in mice. Human RECQ5 is known for its ability to regulate homologous recombination by disrupting RAD51 nucleoprotein filaments. It also binds to RNA polymerase II (RNAPII) and negatively regulates transcript elongation by RNAPII. Here, we summarize recent studies implicating RECQ5 in the prevention and resolution of transcription-replication conflicts, a major intrinsic source of genomic instability during cancer development.
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Affiliation(s)
- Martin Andrs
- Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 143 00 Prague, Czech Republic; (M.A.); (Z.H.); (A.O.); (J.D.)
| | - Zdenka Hasanova
- Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 143 00 Prague, Czech Republic; (M.A.); (Z.H.); (A.O.); (J.D.)
| | - Anna Oravetzova
- Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 143 00 Prague, Czech Republic; (M.A.); (Z.H.); (A.O.); (J.D.)
- Department of Cell Biology, Charles University, Vinicna 7, 128 43 Prague, Czech Republic
| | - Jana Dobrovolna
- Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 143 00 Prague, Czech Republic; (M.A.); (Z.H.); (A.O.); (J.D.)
| | - Pavel Janscak
- Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 143 00 Prague, Czech Republic; (M.A.); (Z.H.); (A.O.); (J.D.)
- Institute of Molecular Cancer Research, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Correspondence:
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23
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Kim JJ, Lee SY, Gong F, Battenhouse AM, Boutz DR, Bashyal A, Refvik ST, Chiang CM, Xhemalce B, Paull TT, Brodbelt JS, Marcotte EM, Miller KM. Systematic bromodomain protein screens identify homologous recombination and R-loop suppression pathways involved in genome integrity. Genes Dev 2019; 33:1751-1774. [PMID: 31753913 PMCID: PMC6942044 DOI: 10.1101/gad.331231.119] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 10/28/2019] [Indexed: 01/01/2023]
Abstract
Bromodomain proteins (BRD) are key chromatin regulators of genome function and stability as well as therapeutic targets in cancer. Here, we systematically delineate the contribution of human BRD proteins for genome stability and DNA double-strand break (DSB) repair using several cell-based assays and proteomic interaction network analysis. Applying these approaches, we identify 24 of the 42 BRD proteins as promoters of DNA repair and/or genome integrity. We identified a BRD-reader function of PCAF that bound TIP60-mediated histone acetylations at DSBs to recruit a DUB complex to deubiquitylate histone H2BK120, to allowing direct acetylation by PCAF, and repair of DSBs by homologous recombination. We also discovered the bromo-and-extra-terminal (BET) BRD proteins, BRD2 and BRD4, as negative regulators of transcription-associated RNA-DNA hybrids (R-loops) as inhibition of BRD2 or BRD4 increased R-loop formation, which generated DSBs. These breaks were reliant on topoisomerase II, and BRD2 directly bound and activated topoisomerase I, a known restrainer of R-loops. Thus, comprehensive interactome and functional profiling of BRD proteins revealed new homologous recombination and genome stability pathways, providing a framework to understand genome maintenance by BRD proteins and the effects of their pharmacological inhibition.
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Affiliation(s)
- Jae Jin Kim
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Seo Yun Lee
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Fade Gong
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Anna M Battenhouse
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Daniel R Boutz
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Aarti Bashyal
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Samantha T Refvik
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,The Howard Hughes Medical Institute
| | - Cheng-Ming Chiang
- Simmons Comprehensive Cancer Center, Department of Biochemistry, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Blerta Xhemalce
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Tanya T Paull
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,The Howard Hughes Medical Institute.,Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, USA.,Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Edward M Marcotte
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Kyle M Miller
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Livestrong Cancer Institutes, Dell Medical School, The University of Texas at Austin, Austin, Texas 78712, USA
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24
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R Loops: From Physiological to Pathological Roles. Cell 2019; 179:604-618. [PMID: 31607512 DOI: 10.1016/j.cell.2019.08.055] [Citation(s) in RCA: 353] [Impact Index Per Article: 70.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/19/2019] [Accepted: 08/28/2019] [Indexed: 12/13/2022]
Abstract
DNA-RNA hybrids play a physiological role in cellular processes, but often, they represent non-scheduled co-transcriptional structures with a negative impact on transcription, replication and DNA repair. Accumulating evidence suggests that they constitute a source of replication stress, DNA breaks and genome instability. Reciprocally, DNA breaks facilitate DNA-RNA hybrid formation by releasing the double helix torsional conformation. Cells avoid DNA-RNA accumulation by either preventing or removing hybrids directly or by DNA repair-coupled mechanisms. Given the R-loop impact on chromatin and genome organization and its potential relation with genetic diseases, we review R-loop homeostasis as well as their physiological and pathological roles.
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25
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Chen FX, Smith ER, Shilatifard A. Born to run: control of transcription elongation by RNA polymerase II. Nat Rev Mol Cell Biol 2019; 19:464-478. [PMID: 29740129 DOI: 10.1038/s41580-018-0010-5] [Citation(s) in RCA: 253] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The dynamic regulation of transcription elongation by RNA polymerase II (Pol II) is an integral part of the implementation of gene expression programmes during development. In most metazoans, the majority of transcribed genes exhibit transient pausing of Pol II at promoter-proximal regions, and the release of Pol II into gene bodies is controlled by many regulatory factors that respond to environmental and developmental cues. Misregulation of the elongation stage of transcription is implicated in cancer and other human diseases, suggesting that mechanistic understanding of transcription elongation control is therapeutically relevant. In this Review, we discuss the features, establishment and maintenance of Pol II pausing, the transition into productive elongation, the control of transcription elongation by enhancers and by factors of other cellular processes, such as topoisomerases and poly(ADP-ribose) polymerases (PARPs), and the potential of therapeutic targeting of the elongation stage of transcription by Pol II.
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Affiliation(s)
- Fei Xavier Chen
- Simpson Querrey Center for Epigenetics and the Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Edwin R Smith
- Simpson Querrey Center for Epigenetics and the Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Ali Shilatifard
- Simpson Querrey Center for Epigenetics and the Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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26
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Girstun A, Ishikawa T, Staron K. Effects of SRSF1 on subnuclear localization of topoisomerase I. J Cell Biochem 2019; 120:11794-11808. [PMID: 30775805 DOI: 10.1002/jcb.28459] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 11/30/2018] [Accepted: 12/06/2018] [Indexed: 01/24/2023]
Abstract
Subnuclear localization of topoisomerase I (top I) is determined by its DNA relaxation activity and a net of its interactions with in majority unidentified nucleolar and nucleoplasmic elements. Here, we recognized SR protein SRSF1 (Serine/arginine-rich splicing factor 1, previously known as SF2/ASF) as a new element of the net. In HeLa cells, overexpression of SRSF1 recruited top I to the nucleoplasm whereas its silencing concentrated it in the nucleolus. Effect of SRSF1 was independent of top I relaxation activity and was the best pronounced for the mutant inactive in relaxation reaction. In HCT116 cells where top I was not released from the nucleolus upon halting relaxation activity, it was also not relocated by elevated level of SRSF1. Out of remaining SR proteins, SRSF5, SRSF7, and SRSF9 did not influence the localization of top I in HeLa cells whereas overexpression of SRSF2, SRSF3, SRSF6, and partly SRSF4 concentrated top I in the nucleolus, most possibly due to the reduction of the SRSF1 accessibility. Specific effect of SRSF1 was exerted because of its distinct RS domain. Silencing of SRSF1 compensated the deletion of the top I N-terminal region, individually responsible for nucleoplasmic localization of the mutant, and restored the wild-type phenotype of deletion mutant localization. SRSF1 was essential for the camptothecin-induced clearance from the nucleolus. These results suggest a possible role of SRSF1 in establishing partition of top I between the nucleolus and the nucleoplasm in some cell types with distinct combinations of SR proteins levels.
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Affiliation(s)
- Agnieszka Girstun
- Department of Molecular Biology, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Takao Ishikawa
- Department of Molecular Biology, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Krzysztof Staron
- Department of Molecular Biology, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Warsaw, Poland
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27
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Olson HC, Davis L, Kiianitsa K, Khoo KJ, Liu Y, Knijnenburg TA, Maizels N. Increased levels of RECQ5 shift DNA repair from canonical to alternative pathways. Nucleic Acids Res 2019; 46:9496-9509. [PMID: 30107528 PMCID: PMC6182128 DOI: 10.1093/nar/gky727] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 08/02/2018] [Indexed: 12/11/2022] Open
Abstract
RECQ5 (RECQL5) is one of several human helicases that dissociates RAD51-DNA filaments. The gene that encodes RECQ5 is frequently amplified in human tumors, but it is not known whether amplification correlates with increased gene expression, or how increased RECQ5 levels affect DNA repair at nicks and double-strand breaks. Here, we address these questions. We show that RECQ5 gene amplification correlates with increased gene expression in human tumors, by in silico analysis of over 9000 individual tumors representing 32 tumor types in the TCGA dataset. We demonstrate that, at double-strand breaks, increased RECQ5 levels inhibited canonical homology-directed repair (HDR) by double-stranded DNA donors, phenocopying the effect of BRCA deficiency. Conversely, at nicks, increased RECQ5 levels stimulated 'alternative' HDR by single-stranded DNA donors, which is normally suppressed by RAD51; this was accompanied by stimulation of mutagenic end-joining. Even modest changes (2-fold) in RECQ5 levels caused significant dysregulation of repair, especially HDR. These results suggest that in some tumors, RECQ5 gene amplification may have profound consequences for genomic instability.
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Affiliation(s)
- Henry C Olson
- Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Luther Davis
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Kostantin Kiianitsa
- Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Kevin J Khoo
- Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA.,Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 E. Duarte Road, Duarte, CA 91010, USA
| | - Theo A Knijnenburg
- Institute for Systems Biology, 401 Terry Ave. N., Seattle, WA 98109, USA
| | - Nancy Maizels
- Department of Biochemistry, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA.,Department of Immunology, University of Washington, 1959 NE Pacific St., Seattle, WA 98195, USA
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28
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Marabitti V, Lillo G, Malacaria E, Palermo V, Sanchez M, Pichierri P, Franchitto A. ATM pathway activation limits R-loop-associated genomic instability in Werner syndrome cells. Nucleic Acids Res 2019; 47:3485-3502. [PMID: 30657978 PMCID: PMC6468170 DOI: 10.1093/nar/gkz025] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 01/22/2023] Open
Abstract
Werner syndrome (WS) is a cancer-prone disease caused by deficiency of Werner protein (WRN). WRN maintains genome integrity by promoting replication-fork stability after various forms of replication stress. Under mild replication stress, WS cells show impaired ATR-mediated CHK1 activation. However, it remains unclear if WS cells elicit other repair pathway. We demonstrate that loss of WRN leads to enhanced ATM phosphorylation upon prolonged exposure to aphidicolin, a specific inhibitor of DNA polymerases, resulting in CHK1 activation. Moreover, we find that loss of WRN sensitises cells to replication-transcription collisions and promotes accumulation of R-loops, which undergo XPG-dependent cleavage responsible for ATM signalling activation. Importantly, we observe that ATM pathway limits chromosomal instability in WS cells. Finally, we prove that, in WS cells, genomic instability enhanced upon chemical inhibition of ATM kinase activity is counteracted by direct or indirect suppression of R-loop formation or by XPG abrogation. Together, these findings suggest a potential role of WRN as regulator of R-loop-associated genomic instability, strengthening the notion that conflicts between replication and transcription can affect DNA replication, leading to human disease and cancer.
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Affiliation(s)
- Veronica Marabitti
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
| | - Giorgia Lillo
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
| | - Eva Malacaria
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
| | - Valentina Palermo
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
| | - Massimo Sanchez
- Department of Cell Biology and Neurosciences, Section of Gene and Cell Therapy, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
| | - Pietro Pichierri
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
| | - Annapaola Franchitto
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita’, Viale Regina Elena 299, Rome 00161, Italy
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29
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The NORAD lncRNA assembles a topoisomerase complex critical for genome stability. Nature 2018; 561:132-136. [DOI: 10.1038/s41586-018-0453-z] [Citation(s) in RCA: 218] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 07/17/2018] [Indexed: 01/08/2023]
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30
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Li M, Xu X, Chang CW, Zheng L, Shen B, Liu Y. SUMO2 conjugation of PCNA facilitates chromatin remodeling to resolve transcription-replication conflicts. Nat Commun 2018; 9:2706. [PMID: 30006506 PMCID: PMC6045570 DOI: 10.1038/s41467-018-05236-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 06/14/2018] [Indexed: 12/27/2022] Open
Abstract
During DNA synthesis, DNA replication and transcription machinery can collide, and the replication fork may temporarily dislodge RNA polymerase II (RNAPII) to resolve the transcription-replication conflict (TRC), a major source of endogenous DNA double-strand breaks (DSBs) and common fragile site (CFS) instability. However, the mechanism of TRC resolution remains unclear. Here, we show that conjugation of SUMO2, but not SUMO1 or SUMO3, to the essential replication factor PCNA is induced on transcribed chromatin by the RNAPII-bound helicase RECQ5. Proteomic analysis reveals that SUMO2-PCNA enriches histone chaperones CAF1 and FACT in the replication complex via interactions with their SUMO-interacting motifs. SUMO2-PCNA enhances CAF1-dependent histone deposition, which correlates with increased histone H3.1 at CFSs and repressive histone marks in the chromatin to reduce chromatin accessibility. Hence, SUMO2-PCNA dislodges RNAPII at CFSs, and overexpressing either SUMO2-PCNA or CAF1 reduces the incidence of DSBs in TRC-prone RECQ5-deficient cells.
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Affiliation(s)
- Min Li
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Xiaohua Xu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Chou-Wei Chang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA, 91010-3000, USA.
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31
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Pozzi B, Mammi P, Bragado L, Giono LE, Srebrow A. When SUMO met splicing. RNA Biol 2018; 15:689-695. [PMID: 29741121 PMCID: PMC6152442 DOI: 10.1080/15476286.2018.1457936] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 02/22/2018] [Accepted: 03/20/2018] [Indexed: 12/12/2022] Open
Abstract
Spliceosomal proteins have been revealed as SUMO conjugation targets. Moreover, we have reported that many of these are in a SUMO-conjugated form when bound to a pre-mRNA substrate during a splicing reaction. We demonstrated that SUMOylation of Prp3 (PRPF3), a component of the U4/U6 di-snRNP, is required for U4/U6•U5 tri-snRNP formation and/or recruitment to active spliceosomes. Expanding upon our previous results, we have shown that the splicing factor SRSF1 stimulates SUMO conjugation to several spliceosomal proteins. Given the relevance of the splicing process, as well as the complex and dynamic nature of its governing machinery, the spliceosome, the molecular mechanisms that modulate its function represent an attractive topic of research. We posit that SUMO conjugation could represent a way of modulating spliceosome assembly and thus, splicing efficiency. How cycles of SUMOylation/de-SUMOylation of spliceosomal proteins become integrated throughout the highly choreographed spliceosomal cycle awaits further investigation.
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Affiliation(s)
- Berta Pozzi
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA- CONICET); Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Buenos Aires, Argentina
| | - Pablo Mammi
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA- CONICET); Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Buenos Aires, Argentina
| | - Laureano Bragado
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA- CONICET); Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Buenos Aires, Argentina
| | - Luciana E. Giono
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA- CONICET); Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Buenos Aires, Argentina
| | - Anabella Srebrow
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA- CONICET); Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Ciudad Universitaria, Buenos Aires, Argentina
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Kotsantis P, Petermann E, Boulton SJ. Mechanisms of Oncogene-Induced Replication Stress: Jigsaw Falling into Place. Cancer Discov 2018; 8:537-555. [PMID: 29653955 DOI: 10.1158/2159-8290.cd-17-1461] [Citation(s) in RCA: 232] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/26/2018] [Accepted: 03/09/2018] [Indexed: 12/31/2022]
Abstract
Oncogene activation disturbs cellular processes and accommodates a complex landscape of changes in the genome that contribute to genomic instability, which accelerates mutation rates and promotes tumorigenesis. Part of this cellular turmoil involves deregulation of physiologic DNA replication, widely described as replication stress. Oncogene-induced replication stress is an early driver of genomic instability and is attributed to a plethora of factors, most notably aberrant origin firing, replication-transcription collisions, reactive oxygen species, and defective nucleotide metabolism.Significance: Replication stress is a fundamental step and an early driver of tumorigenesis and has been associated with many activated oncogenes. Deciphering the mechanisms that contribute to the replication stress response may provide new avenues for targeted cancer treatment. In this review, we discuss the latest findings on the DNA replication stress response and examine the various mechanisms through which activated oncogenes induce replication stress. Cancer Discov; 8(5); 537-55. ©2018 AACR.
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Affiliation(s)
| | - Eva Petermann
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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33
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Abstract
Topoisomerase I (Top1) resolves torsional stress that accumulates during transcription, replication and chromatin remodeling by introducing a transient single-strand break in DNA. The cleavage activity of Top1 has opposing roles, either promoting or destabilizing genome integrity depending on the context. Resolution of transcription-associated negative supercoils, for example, prevents pairing of the nascent RNA with the DNA template (R-loops) as well as DNA secondary structure formation. Reduced Top1 levels thus enhance CAG repeat contraction, somatic hypermutation, and class switch recombination. Actively transcribed ribosomal DNA is also destabilized in the absence of Top1, reflecting the importance of Top1 in ensuring efficient transcription. In terms of promoting genome instability, an aborted Top1 catalytic cycle stimulates deletions at short tandem repeats and the enzyme's transesterification activity supports illegitimate recombination. Finally, Top1 incision at ribonucleotides embedded in DNA generates deletions in tandem repeats, and induces gross chromosomal rearrangements and mitotic recombination.
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Affiliation(s)
- Jang-Eun Cho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, CARL 384, Durham, NC, 27710, USA
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, CARL 384, Durham, NC, 27710, USA.
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34
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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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Stirnweiss A, Oommen J, Kotecha RS, Kees UR, Beesley AH. Molecular-genetic profiling and high-throughput in vitro drug screening in NUT midline carcinoma-an aggressive and fatal disease. Oncotarget 2017; 8:112313-112329. [PMID: 29348827 PMCID: PMC5762512 DOI: 10.18632/oncotarget.22862] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 11/26/2017] [Indexed: 12/11/2022] Open
Abstract
NUT midline carcinoma (NMC) is a rare and aggressive cancer, with survival typically less than seven months, that can arise in people of any age. Genetically, NMC is defined by the chromosomal fusion of NUTM1 with a chromatin-binding partner, typically the bromodomain-containing protein BRD4. However, little is known about other genetic aberrations in this disease. In this study, we used a unique panel of cell lines to describe the molecular-genetic features of NMC. Next-generation sequencing identified a recurring high-impact mutation in the DNA-helicase gene RECQL5 in 75% of lines studied, and biological signals from mutation-signature and network analyses consistent with a general failure in DNA-repair. A high-throughput drug screen confirmed that microtubule inhibitors, topoisomerase inhibitors and anthracyclines are highly cytotoxic in the majority of NMC lines, and that cell lines expressing the BRD4-NUTM1 (exon11:exon2) variant are an order of magnitude more responsive to bromodomain inhibitors (iBETs) on average than those with other BRD4-NUTM1 translocation variants. We also identified a highly significant correlation between iBET and aurora kinase inhibitor efficacy in this study. Integration of exome sequencing, transcriptome, and drug sensitivity profiles suggested that aberrant activity of the nuclear receptor co-activator NCOA3 may correlate with poor response to iBETs. In conclusion, our data emphasize the heterogeneity of NMC and highlights genetic aberrations that could be explored to improve therapeutic strategies. The novel finding of a recurring RECQL5 mutation, together with recent reports of chromoplexy in this disease, suggests that DNA-repair pathways are likely to play a central role in NMC tumorigenesis.
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Affiliation(s)
- Anja Stirnweiss
- Leukaemia and Cancer Genetics Program, Telethon Kids Institute, The University of Western Australia, Perth, Australia.,Drug Discovery Group, Telethon Kids Institute, The University of Western Australia, Perth, Australia
| | - Joyce Oommen
- Leukaemia and Cancer Genetics Program, Telethon Kids Institute, The University of Western Australia, Perth, Australia
| | - Rishi S Kotecha
- Leukaemia and Cancer Genetics Program, Telethon Kids Institute, The University of Western Australia, Perth, Australia.,Department of Haematology and Oncology, Princess Margaret Hospital for Children, Perth, Australia.,School of Paediatrics and Child Health, University of Western Australia, Perth, Australia
| | - Ursula R Kees
- Leukaemia and Cancer Genetics Program, Telethon Kids Institute, The University of Western Australia, Perth, Australia
| | - Alex H Beesley
- Leukaemia and Cancer Genetics Program, Telethon Kids Institute, The University of Western Australia, Perth, Australia
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36
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Boulianne B, Feldhahn N. Transcribing malignancy: transcription-associated genomic instability in cancer. Oncogene 2017; 37:971-981. [DOI: 10.1038/onc.2017.402] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/12/2017] [Accepted: 09/12/2017] [Indexed: 12/17/2022]
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37
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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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38
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Parajuli S, Teasley DC, Murali B, Jackson J, Vindigni A, Stewart SA. Human ribonuclease H1 resolves R-loops and thereby enables progression of the DNA replication fork. J Biol Chem 2017; 292:15216-15224. [PMID: 28717002 DOI: 10.1074/jbc.m117.787473] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/21/2017] [Indexed: 11/06/2022] Open
Abstract
Faithful DNA replication is essential for genome stability. To ensure accurate replication, numerous complex and redundant replication and repair mechanisms function in tandem with the core replication proteins to ensure DNA replication continues even when replication challenges are present that could impede progression of the replication fork. A unique topological challenge to the replication machinery is posed by RNA-DNA hybrids, commonly referred to as R-loops. Although R-loops play important roles in gene expression and recombination at immunoglobulin sites, their persistence is thought to interfere with DNA replication by slowing or impeding replication fork progression. Therefore, it is of interest to identify DNA-associated enzymes that help resolve replication-impeding R-loops. Here, using DNA fiber analysis, we demonstrate that human ribonuclease H1 (RNH1) plays an important role in replication fork movement in the mammalian nucleus by resolving R-loops. We found that RNH1 depletion results in accumulation of RNA-DNA hybrids, slowing of replication forks, and increased DNA damage. Our data uncovered a role for RNH1 in global DNA replication in the mammalian nucleus. Because accumulation of RNA-DNA hybrids is linked to various human cancers and neurodegenerative disorders, our study raises the possibility that replication fork progression might be impeded, adding to increased genomic instability and contributing to disease.
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Affiliation(s)
| | | | - Bhavna Murali
- From the Departments of Cell Biology and Physiology and
| | - Jessica Jackson
- the Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104
| | - Alessandro Vindigni
- the Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri 63104 .,Siteman Cancer Center, and
| | - Sheila A Stewart
- From the Departments of Cell Biology and Physiology and .,Siteman Cancer Center, and.,Medicine.,Integrating Communications within the Cancer Environment (ICCE) Institute, Washington University School of Medicine, St. Louis, Missouri 63110 and
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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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Wei L, Zhao X. Roles of SUMO in Replication Initiation, Progression, and Termination. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:371-393. [PMID: 29357067 PMCID: PMC6643980 DOI: 10.1007/978-981-10-6955-0_17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Accurate genome duplication during cell division is essential for life. This process is accomplished by the close collaboration between replication factors and many additional proteins that provide assistant roles. Replication factors establish the replication machineries capable of copying billions of nucleotides, while regulatory proteins help to achieve accuracy and efficiency of replication. Among regulatory proteins, protein modification enzymes can bestow fast and reversible changes to many targets, leading to coordinated effects on replication. Recent studies have begun to elucidate how one type of protein modification, sumoylation, can modify replication proteins and regulate genome duplication through multiple mechanisms. This chapter summarizes these new findings, and how they can integrate with the known regulatory circuitries of replication. As this area of research is still at its infancy, many outstanding questions remain to be explored, and we discuss these issues in light of the new advances.
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Affiliation(s)
- Lei Wei
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Xiaolan Zhao
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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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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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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Li M, Liu Y. Topoisomerase I in Human Disease Pathogenesis and Treatments. GENOMICS PROTEOMICS & BIOINFORMATICS 2016; 14:166-171. [PMID: 27181710 PMCID: PMC4936607 DOI: 10.1016/j.gpb.2016.02.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 02/17/2016] [Accepted: 02/22/2016] [Indexed: 11/24/2022]
Abstract
Mammalian topoisomerase 1 (TOP1) is an essential enzyme for normal development. TOP1 relaxes supercoiled DNA to remove helical constraints that can otherwise hinder DNA replication and transcription and thus block cell growth. Unfortunately, this exact activity can covalently trap TOP1 on the DNA that could lead to cell death or mutagenesis, a precursor for tumorigenesis. It is therefore important for cells to find a proper balance between the utilization of the TOP1 catalytic activity to maintain DNA topology and the risk of accumulating the toxic DNA damages due to TOP1 trapping that prevents normal cell growth. In an apparent contradiction to the negative attribute of the TOP1 activity to genome stability, the detrimental effect of the TOP1-induced DNA lesions on cell survival has made this enzyme a prime target for cancer therapies to kill fast-growing cancer cells. In addition, cumulative evidence supports a direct role of TOP1 in promoting transcriptional progression independent of its topoisomerase activity. The involvement of TOP1 in transcriptional regulation has recently become a focus in developing potential new treatments for a subtype of autism spectrum disorders. Clearly, the impact of TOP1 on human health is multifold. In this review, we will summarize our current understandings on how TOP1 contributes to human diseases and how its activity is targeted for disease treatments.
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Affiliation(s)
- Min Li
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA
| | - Yilun Liu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, Duarte, CA 91010-3000, USA.
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Wu CS, Zou L. The SUMO (Small Ubiquitin-like Modifier) Ligase PIAS3 Primes ATR for Checkpoint Activation. J Biol Chem 2015; 291:279-90. [PMID: 26565033 DOI: 10.1074/jbc.m115.691170] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Indexed: 12/22/2022] Open
Abstract
The maintenance of genomic stability relies on the concerted action of DNA repair and DNA damage signaling pathways. The PIAS (protein inhibitor of activated STAT) family of SUMO (small ubiquitin-like modifier) ligases has been implicated in DNA repair, but whether it plays a role in DNA damage signaling is still unclear. Here, we show that the PIAS3 SUMO ligase is important for activation of the ATR (ataxia telangiectasia and Rad3 related)-regulated DNA damage signaling pathway. PIAS3 is the only member of the PIAS family that is indispensable for ATR activation. In response to different types of DNA damage and replication stress, PIAS3 plays multiple roles in ATR activation. In cells treated with camptothecin (CPT), PIAS3 contributes to formation of DNA double-stranded breaks. In UV (ultraviolet light)- or HU (hydroxyurea)-treated cells, PIAS3 is required for efficient ATR autophosphorylation, one of the earliest events during ATR activation. Although PIAS3 is dispensable for ATRIP (ATR-interacting protein) SUMOylation and the ATR-ATRIP interaction, it is required for maintaining the basal kinase activity of ATR prior to DNA damage. In the absence of PIAS3, ATR fails to display normal kinase activity after DNA damage, which accompanies with reduced phosphorylation of ATR substrates. Together, these results suggest that PIAS3 primes ATR for checkpoint activation by sustaining its basal kinase activity, revealing a new function of the PIAS family in DNA damage signaling.
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Affiliation(s)
- Ching-Shyi Wu
- From the Massachusetts General Hospital (MGH) Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129 and
| | - Lee Zou
- From the Massachusetts General Hospital (MGH) Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129 and Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02115
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Santos-Pereira JM, Aguilera A. R loops: new modulators of genome dynamics and function. Nat Rev Genet 2015; 16:583-97. [PMID: 26370899 DOI: 10.1038/nrg3961] [Citation(s) in RCA: 517] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
R loops are nucleic acid structures composed of an RNA-DNA hybrid and a displaced single-stranded DNA. Recently, evidence has emerged that R loops occur more often in the genome and have greater physiological relevance, including roles in transcription and chromatin structure, than was previously predicted. Importantly, however, R loops are also a major threat to genome stability. For this reason, several DNA and RNA metabolism factors prevent R-loop formation in cells. Dysfunction of these factors causes R-loop accumulation, which leads to replication stress, genome instability, chromatin alterations or gene silencing, phenomena that are frequently associated with cancer and a number of genetic diseases. We review the current knowledge of the mechanisms controlling R loops and their putative relationship with disease.
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Affiliation(s)
- José M Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Av. Américo Vespucio s/n, Seville 41092, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Av. Américo Vespucio s/n, Seville 41092, Spain
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