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Zhang F, Sun J, Zhang L, Li R, Wang Y, Geng H, Shen C, Li L, Chen L. PARP inhibition leads to synthetic lethality with key splicing-factor mutations in myelodysplastic syndromes. Br J Cancer 2024:10.1038/s41416-024-02729-0. [PMID: 38806724 DOI: 10.1038/s41416-024-02729-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 05/30/2024] Open
Abstract
BACKGROUND Splicing factors are frequently mutated in patients with myelodysplastic syndromes and acute myeloid leukaemia. Recent studies have revealed convergent molecular defects caused by splicing factor mutations, among which R-loop dysregulation and resultant genome instability are suggested as contributing factors to disease progression. On the other hand, understanding how mutant cells survive upon aberrant R-loop formation and genome instability is essential for developing novel therapeutics. METHODS The immunoprecipitation was performed to identify R-loops in association with PARP1/poly-ADP-ribosylation. The western blot, immunofluorescence, and flow cytometry assays were used to test the cell viability, cell cycle arrest, apoptosis, and ATM activation in mutant cells following the treatment of the PARP inhibitor. The Srsf2(P95H) knock-in murine hematopoietic cells and MLL-AF9 transformed leukaemia model were generated to investigate the potential of the PARP inhibitor as a therapy for haematological malignancies. RESULTS The disease-causing mutations in SRSF2 activate PARP and elevate the overall poly-ADP-ribosylation levels of proteins in response to R-loop dysregulation. In accordance, mutant cells are more vulnerable to the PARP inhibitors in comparison to the wild-type counterpart. Notably, the synthetic lethality was further validated in the Srsf2(P95H) knock-in murine hematopoietic cell and MLL-AF9 leukaemia model. CONCLUSIONS Our findings suggest that mutant cells antagonise the genome threat caused by R-loop disruption by PARP activation, thus making PARP targeting a promising therapeutic strategy for myeloid cancers with mutations in SRSF2.
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Affiliation(s)
- Fangliang Zhang
- RNA Institute, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jianai Sun
- Department of Hematological Malignancies Translational Science, Gehr Family Center for Leukemia Research, Hematologic Malignancies and Stem Cell Transplantation Institute, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA
- Department of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Lei Zhang
- Department of Hematological Malignancies Translational Science, Gehr Family Center for Leukemia Research, Hematologic Malignancies and Stem Cell Transplantation Institute, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA
| | - Ruiqi Li
- RNA Institute, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yanzhen Wang
- RNA Institute, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Huichao Geng
- RNA Institute, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Chao Shen
- RNA Institute, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China
| | - Ling Li
- Department of Hematological Malignancies Translational Science, Gehr Family Center for Leukemia Research, Hematologic Malignancies and Stem Cell Transplantation Institute, Beckman Research Institute, City of Hope Medical Center, Duarte, CA, USA.
| | - Liang Chen
- RNA Institute, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.
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2
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Imaduwage I, Hewadikaram M. Predicted roles of long non-coding RNAs in abiotic stress tolerance responses of plants. MOLECULAR HORTICULTURE 2024; 4:20. [PMID: 38745264 PMCID: PMC11094901 DOI: 10.1186/s43897-024-00094-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 04/06/2024] [Indexed: 05/16/2024]
Abstract
The plant genome exhibits a significant amount of transcriptional activity, with most of the resulting transcripts lacking protein-coding potential. Non-coding RNAs play a pivotal role in the development and regulatory processes in plants. Long non-coding RNAs (lncRNAs), which exceed 200 nucleotides, may play a significant role in enhancing plant resilience to various abiotic stresses, such as excessive heat, drought, cold, and salinity. In addition, the exogenous application of chemicals, such as abscisic acid and salicylic acid, can augment plant defense responses against abiotic stress. While how lncRNAs play a role in abiotic stress tolerance is relatively well-studied in model plants, this review provides a comprehensive overview of the current understanding of this function in horticultural crop plants. It also delves into the potential role of lncRNAs in chemical priming of plants in order to acquire abiotic stress tolerance, although many limitations exist in proving lncRNA functionality under such conditions.
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Affiliation(s)
- Iuh Imaduwage
- Department of Biomedical Sciences, Faculty of Science, NSBM Green University, Pitipana, Homagama, Sri Lanka
| | - Madhavi Hewadikaram
- Department of Biomedical Sciences, Faculty of Science, NSBM Green University, Pitipana, Homagama, Sri Lanka.
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3
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Hyder U, Challa A, Thornton M, Nandu T, Kraus WL, D’Orso I. KAP1 negatively regulates RNA polymerase II elongation kinetics to activate signal-induced transcription. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.05.592422. [PMID: 38746145 PMCID: PMC11092767 DOI: 10.1101/2024.05.05.592422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Signal-induced transcriptional programs regulate critical biological processes through the precise spatiotemporal activation of Immediate Early Genes (IEGs); however, the mechanisms of transcription induction remain poorly understood. By combining an acute depletion system with high resolution genomics approaches to interrogate synchronized, temporal transcription, we reveal that KAP1/TRIM28 is a first responder that fulfills the temporal and heightened transcriptional demand of IEGs. Unexpectedly, acute KAP1 loss triggers an increase in RNA polymerase II elongation kinetics during early stimulation time points. This elongation defect derails the normal progression through the transcriptional cycle during late stimulation time points, ultimately leading to decreased recruitment of the transcription apparatus for re-initiation thereby dampening IEGs transcriptional output. Collectively, KAP1 plays a counterintuitive role by negatively regulating transcription elongation to support full activation across multiple transcription cycles of genes critical for cell physiology and organismal functions.
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Affiliation(s)
- Usman Hyder
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ashwini Challa
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Micah Thornton
- Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tulip Nandu
- Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - W. Lee Kraus
- Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Iván D’Orso
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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4
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Das P, Hazra A, Saha S, Roy S, Mukherjee M, Hazra S, Majumdar HK, BoseDasgupta S. Resolving the polycistronic aftermath: Essential role of topoisomerase IA in preventing R-loops in Leishmania. J Biol Chem 2024; 300:107162. [PMID: 38484800 PMCID: PMC11021369 DOI: 10.1016/j.jbc.2024.107162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 02/10/2024] [Accepted: 02/26/2024] [Indexed: 04/14/2024] Open
Abstract
Kinetoplastid parasites are "living bridges" in the evolution from prokaryotes to higher eukaryotes. The near-intronless genome of the kinetoplastid Leishmania exhibits polycistronic transcription which can facilitate R-loop formation. Therefore, to prevent such DNA-RNA hybrids, Leishmania has retained prokaryotic-like DNA Topoisomerase IA (LdTOPIA) in the course of evolution. LdTOPIA is an essential enzyme that is expressed ubiquitously and is adapted for the compartmentalized eukaryotic form in harboring functional bipartite nuclear localization signals. Although exhibiting greater homology to mycobacterial TOPIA, LdTOPIA could functionally complement the growth lethality of Escherichia coli TOPIA null GyrB ts strain at non-permissive temperatures. Purified LdTOPIA exhibits Mg2+-dependent relaxation of only negatively supercoiled DNA and preference towards single-stranded DNA substrates. LdTOPIA prevents nuclear R-loops as conditional LdTOPIA downregulated parasites exhibit R-loop formation and thereby parasite killing. The clinically used tricyclic antidepressant, norclomipramine could specifically inhibit LdTOPIA and lead to R-loop formation and parasite elimination. This comprehensive study therefore paves an avenue for drug repurposing against Leishmania.
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Affiliation(s)
- Payel Das
- Molecular Immunology and Cellular Microbiology Laboratory, Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Arnab Hazra
- Molecular Immunology and Cellular Microbiology Laboratory, Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Saradindu Saha
- Molecular Immunology and Cellular Microbiology Laboratory, Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Sadhana Roy
- Molecular Immunology and Cellular Microbiology Laboratory, Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Mandrita Mukherjee
- Molecular Immunology and Cellular Microbiology Laboratory, Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Saugata Hazra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, India
| | - Hemanta K Majumdar
- Infectious Diseases and Immunology Division, CSIR- Indian Institute of Chemical Biology, Kolkata, India
| | - Somdeb BoseDasgupta
- Molecular Immunology and Cellular Microbiology Laboratory, Department of Bioscience and Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India.
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5
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Valenzisi P, Marabitti V, Pichierri P, Franchitto A. WRNIP1 prevents transcription-associated genomic instability. eLife 2024; 12:RP89981. [PMID: 38488661 PMCID: PMC10942783 DOI: 10.7554/elife.89981] [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: 03/17/2024] Open
Abstract
R-loops are non-canonical DNA structures that form during transcription and play diverse roles in various physiological processes. Disruption of R-loop homeostasis can lead to genomic instability and replication impairment, contributing to several human diseases, including cancer. Although the molecular mechanisms that protect cells against such events are not fully understood, recent research has identified fork protection factors and DNA damage response proteins as regulators of R-loop dynamics. In this study, we identify the Werner helicase-interacting protein 1 (WRNIP1) as a novel factor that counteracts transcription-associated DNA damage upon replication perturbation. Loss of WRNIP1 leads to R-loop accumulation, resulting in collisions between the replisome and transcription machinery. We observe co-localization of WRNIP1 with transcription/replication complexes and R-loops after replication perturbation, suggesting its involvement in resolving transcription-replication conflicts. Moreover, WRNIP1-deficient cells show impaired replication restart from transcription-induced fork stalling. Notably, transcription inhibition and RNase H1 overexpression rescue all the defects caused by loss of WRNIP1. Importantly, our findings highlight the critical role of WRNIP1 ubiquitin-binding zinc finger (UBZ) domain in preventing pathological persistence of R-loops and limiting DNA damage, thereby safeguarding genome integrity.
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Affiliation(s)
- Pasquale Valenzisi
- Section of Mechanisms Biomarkers and Models, Department of Environment and Health, Istituto Superiore di SanitaRomeItaly
| | - Veronica Marabitti
- Section of Mechanisms Biomarkers and Models, Department of Environment and Health, Istituto Superiore di SanitaRomeItaly
| | - Pietro Pichierri
- Section of Mechanisms Biomarkers and Models, Department of Environment and Health, Istituto Superiore di SanitaRomeItaly
| | - Annapaola Franchitto
- Section of Mechanisms Biomarkers and Models, Department of Environment and Health, Istituto Superiore di SanitaRomeItaly
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6
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Janissen R, Barth R, Polinder M, van der Torre J, Dekker C. Single-molecule visualization of twin-supercoiled domains generated during transcription. Nucleic Acids Res 2024; 52:1677-1687. [PMID: 38084930 PMCID: PMC10899792 DOI: 10.1093/nar/gkad1181] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/13/2023] [Accepted: 11/30/2023] [Indexed: 02/29/2024] Open
Abstract
Transcription-coupled supercoiling of DNA is a key factor in chromosome compaction and the regulation of genetic processes in all domains of life. It has become common knowledge that, during transcription, the DNA-dependent RNA polymerase (RNAP) induces positive supercoiling ahead of it (downstream) and negative supercoils in its wake (upstream), as rotation of RNAP around the DNA axis upon tracking its helical groove gets constrained due to drag on its RNA transcript. Here, we experimentally validate this so-called twin-supercoiled-domain model with in vitro real-time visualization at the single-molecule scale. Upon binding to the promoter site on a supercoiled DNA molecule, RNAP merges all DNA supercoils into one large pinned plectoneme with RNAP residing at its apex. Transcription by RNAP in real time demonstrates that up- and downstream supercoils are generated simultaneously and in equal portions, in agreement with the twin-supercoiled-domain model. Experiments carried out in the presence of RNases A and H, revealed that an additional viscous drag of the RNA transcript is not necessary for the RNAP to induce supercoils. The latter results contrast the current consensus and simulations on the origin of the twin-supercoiled domains, pointing at an additional mechanistic cause underlying supercoil generation by RNAP in transcription.
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Affiliation(s)
- Richard Janissen
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, South-Holland 2629HZ, The Netherlands
| | - Roman Barth
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, South-Holland 2629HZ, The Netherlands
| | - Minco Polinder
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, South-Holland 2629HZ, The Netherlands
| | - Jaco van der Torre
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, South-Holland 2629HZ, The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, South-Holland 2629HZ, The Netherlands
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7
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Huffines AK, Schneider DA. Hmo1 Promotes Efficient Transcription Elongation by RNA Polymerase I in Saccharomyces cerevisiae. Genes (Basel) 2024; 15:247. [PMID: 38397236 PMCID: PMC10888141 DOI: 10.3390/genes15020247] [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: 01/09/2024] [Revised: 02/08/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
RNA polymerase I (Pol I) is responsible for synthesizing the three largest eukaryotic ribosomal RNAs (rRNAs), which form the backbone of the ribosome. Transcription by Pol I is required for cell growth and, therefore, is subject to complex and intricate regulatory mechanisms. To accomplish this robust regulation, the cell engages a series of trans-acting transcription factors. One such factor, high mobility group protein 1 (Hmo1), has long been established as a trans-acting factor for Pol I in Saccharomyces cerevisiae; however, the mechanism by which Hmo1 promotes rRNA synthesis has not been defined. Here, we investigated the effect of the deletion of HMO1 on transcription elongation by Pol I in vivo. We determined that Hmo1 is an important activator of transcription elongation, and without this protein, Pol I accumulates across rDNA in a sequence-specific manner. Our results demonstrate that Hmo1 promotes efficient transcription elongation by rendering Pol I less sensitive to pausing in the G-rich regions of rDNA.
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Affiliation(s)
| | - David A. Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
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8
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Pinto LM, Pailas A, Bondarchenko M, Sharma AB, Neumann K, Rizzo AJ, Jeanty C, Nicot N, Racca C, Graham MK, Naughton C, Liu Y, Chen CL, Meakin PJ, Gilbert N, Britton S, Meeker AK, Heaphy CM, Larminat F, Van Dyck E. DAXX promotes centromeric stability independently of ATRX by preventing the accumulation of R-loop-induced DNA double-stranded breaks. Nucleic Acids Res 2024; 52:1136-1155. [PMID: 38038252 PMCID: PMC10853780 DOI: 10.1093/nar/gkad1141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/08/2023] [Accepted: 11/13/2023] [Indexed: 12/02/2023] Open
Abstract
Maintaining chromatin integrity at the repetitive non-coding DNA sequences underlying centromeres is crucial to prevent replicative stress, DNA breaks and genomic instability. The concerted action of transcriptional repressors, chromatin remodelling complexes and epigenetic factors controls transcription and chromatin structure in these regions. The histone chaperone complex ATRX/DAXX is involved in the establishment and maintenance of centromeric chromatin through the deposition of the histone variant H3.3. ATRX and DAXX have also evolved mutually-independent functions in transcription and chromatin dynamics. Here, using paediatric glioma and pancreatic neuroendocrine tumor cell lines, we identify a novel ATRX-independent function for DAXX in promoting genome stability by preventing transcription-associated R-loop accumulation and DNA double-strand break formation at centromeres. This function of DAXX required its interaction with histone H3.3 but was independent of H3.3 deposition and did not reflect a role in the repression of centromeric transcription. DAXX depletion mobilized BRCA1 at centromeres, in line with BRCA1 role in counteracting centromeric R-loop accumulation. Our results provide novel insights into the mechanisms protecting the human genome from chromosomal instability, as well as potential perspectives in the treatment of cancers with DAXX alterations.
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Affiliation(s)
- Lia M Pinto
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
- Faculty of Science, Technology and Communication, University of Luxembourg, L-4365 Esch-sur-Alzette, Luxembourg
- Discovery & Translational Science Department, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Alexandros Pailas
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
- Faculty of Science, Technology and Communication, University of Luxembourg, L-4365 Esch-sur-Alzette, Luxembourg
| | - Max Bondarchenko
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
- Faculty of Science, Technology and Communication, University of Luxembourg, L-4365 Esch-sur-Alzette, Luxembourg
| | - Abhishek Bharadwaj Sharma
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
| | - Katrin Neumann
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
| | - Anthony J Rizzo
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Céline Jeanty
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
| | - Nathalie Nicot
- Translational Medicine Operations Hub, Luxembourg Institute of Health (LIH), Luxembourg, Luxembourg
| | - Carine Racca
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), 31077 Toulouse Cedex 4, France
| | - Mindy K Graham
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Catherine Naughton
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 1QY, UK
| | - Yaqun Liu
- Institut Curie, PSL Research University, CNRS UMR3244, Dynamics of Genetic Information, Sorbonne Université, 75248 Paris Cedex 05, France
| | - Chun-Long Chen
- Institut Curie, PSL Research University, CNRS UMR3244, Dynamics of Genetic Information, Sorbonne Université, 75248 Paris Cedex 05, France
| | - Paul J Meakin
- Discovery & Translational Science Department, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Nick Gilbert
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh EH4 1QY, UK
| | - Sébastien Britton
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), 31077 Toulouse Cedex 4, France
| | - Alan K Meeker
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Christopher M Heaphy
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Florence Larminat
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III - Paul Sabatier (UT3), 31077 Toulouse Cedex 4, France
| | - Eric Van Dyck
- DNA Repair and Chemoresistance Group, Department of Cancer Research, Luxembourg Institute of Health (LIH), L-1210 Luxembourg, Luxembourg
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9
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Ramos-Alonso L, Chymkowitch P. Maintaining transcriptional homeostasis during cell cycle. Transcription 2024; 15:1-21. [PMID: 37655806 PMCID: PMC11093055 DOI: 10.1080/21541264.2023.2246868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 09/02/2023] Open
Abstract
The preservation of gene expression patterns that define cellular identity throughout the cell division cycle is essential to perpetuate cellular lineages. However, the progression of cells through different phases of the cell cycle severely disrupts chromatin accessibility, epigenetic marks, and the recruitment of transcriptional regulators. Notably, chromatin is transiently disassembled during S-phase and undergoes drastic condensation during mitosis, which is a significant challenge to the preservation of gene expression patterns between cell generations. This article delves into the specific gene expression and chromatin regulatory mechanisms that facilitate the preservation of transcriptional identity during replication and mitosis. Furthermore, we emphasize our recent findings revealing the unconventional role of yeast centromeres and mitotic chromosomes in maintaining transcriptional fidelity beyond mitosis.
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Affiliation(s)
- Lucía Ramos-Alonso
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Pierre Chymkowitch
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
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10
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Lin P, Lourenco C, Cruickshank J, Palomero L, van Leeuwen JE, Tong AHY, Chan K, El Ghamrasni S, Pujana MA, Cescon DW, Moffat J, Penn LZ. Topoisomerase 1 Inhibition in MYC-Driven Cancer Promotes Aberrant R-Loop Accumulation to Induce Synthetic Lethality. Cancer Res 2023; 83:4015-4029. [PMID: 37987734 PMCID: PMC10722143 DOI: 10.1158/0008-5472.can-22-2948] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 07/31/2023] [Accepted: 10/05/2023] [Indexed: 11/21/2023]
Abstract
MYC is a central regulator of gene transcription and is frequently dysregulated in human cancers. As targeting MYC directly is challenging, an alternative strategy is to identify specific proteins or processes required for MYC to function as a potent cancer driver that can be targeted to result in synthetic lethality. To identify potential targets in MYC-driven cancers, we performed a genome-wide CRISPR knockout screen using an isogenic pair of breast cancer cell lines in which MYC dysregulation is the switch from benign to transformed tumor growth. Proteins that regulate R-loops were identified as a potential class of synthetic lethal targets. Dysregulated MYC elevated global transcription and coincident R-loop accumulation. Topoisomerase 1 (TOP1), a regulator of R-loops by DNA topology, was validated to be a vulnerability in cells with high MYC activity. Genetic knockdown of TOP1 in MYC-transformed cells resulted in reduced colony formation compared with control cells, demonstrating synthetic lethality. Overexpression of RNaseH1, a riboendonuclease that specifically degrades R-loops, rescued the reduction in clonogenicity induced by TOP1 deficiency, demonstrating that this vulnerability is driven by aberrant R-loop accumulation. Genetic and pharmacologic TOP1 inhibition selectively reduced the fitness of MYC-transformed tumors in vivo. Finally, drug response to TOP1 inhibitors (i.e., topotecan) significantly correlated with MYC levels and activity across panels of breast cancer cell lines and patient-derived organoids. Together, these results highlight TOP1 as a promising target for MYC-driven cancers. SIGNIFICANCE CRISPR screening reveals topoisomerase 1 as an immediately actionable vulnerability in cancers harboring MYC as a driver oncoprotein that can be targeted with clinically approved inhibitors.
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Affiliation(s)
- Peter Lin
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - Corey Lourenco
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | | | - Luis Palomero
- ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Spain
| | - Jenna E. van Leeuwen
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | | | | | - Samah El Ghamrasni
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - Miquel Angel Pujana
- ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Spain
- CIBERES, Instituto de Salud Carlos III, Madrid, Spain
| | - David W. Cescon
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
- Division of Medical Oncology and Hematology, Department of Medicine, University of Toronto, Toronto, Canada
| | - Jason Moffat
- Donnelly Centre, University of Toronto, Toronto, Canada
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
- Institute for Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Linda Z. Penn
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
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11
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Malina J, Kostrhunova H, Song H, Scott P, Brabec V. Asymmetric triplex metallohelices stabilise DNA G-quadruplexes in promoter oncogene sequences and efficiently reduce their expression in cancer cells. J Enzyme Inhib Med Chem 2023; 38:2198678. [PMID: 37019444 PMCID: PMC10078150 DOI: 10.1080/14756366.2023.2198678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Abstract
Some metallo-supramolecular helical assemblies with size, shape, charge and amphipathic architectures similar to short cationic α-helical peptides have been shown to target and stabilise DNA G-quadruplexes (G4s) in vitro and downregulate the expression of G4-regulated genes in human cells. To expand the library of metallohelical structures that can act as efficient DNA G4 binders and downregulate genes containing G4-forming sequences in their promoter regions, we investigated the interaction of the two enantiomeric pairs of asymmetric Fe(II) triplex metallohelices with a series of five different DNA G4s formed by the human telomeric sequence (hTelo) and in the promoter regions of c-MYC, c-KIT, and k-RAS oncogenes. The metallohelices display preferential binding to G4s over duplex DNA in all investigated G4-forming sequences and induced arrest of DNA polymerase on template strands containing G4-forming sequences. Moreover, the investigated metallohelices suppressed the expression of c-MYC and k-RAS genes at mRNA and protein levels in HCT116 human cancer cells, as revealed by RT-qPCR analysis and western blotting.
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Affiliation(s)
- Jaroslav Malina
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic
| | - Hana Kostrhunova
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic
| | - Hualong Song
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Peter Scott
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Viktor Brabec
- Czech Academy of Sciences, Institute of Biophysics, Brno, Czech Republic
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12
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Kalmykova A. Telomere Checkpoint in Development and Aging. Int J Mol Sci 2023; 24:15979. [PMID: 37958962 PMCID: PMC10647821 DOI: 10.3390/ijms242115979] [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: 09/01/2023] [Revised: 10/19/2023] [Accepted: 11/02/2023] [Indexed: 11/15/2023] Open
Abstract
The maintenance of genome integrity through generations is largely determined by the stability of telomeres. Increasing evidence suggests that telomere dysfunction may trigger changes in cell fate, independently of telomere length. Telomeric multiple tandem repeats are potentially highly recombinogenic. Heterochromatin formation, transcriptional repression, the suppression of homologous recombination and chromosome end protection are all required for telomere stability. Genetic and epigenetic defects affecting telomere homeostasis may cause length-independent internal telomeric DNA damage. Growing evidence, including that based on Drosophila research, points to a telomere checkpoint mechanism that coordinates cell fate with telomere state. According to this scenario, telomeres, irrespective of their length, serve as a primary sensor of genome instability that is capable of triggering cell death or developmental arrest. Telomeric factors released from shortened or dysfunctional telomeres are thought to mediate these processes. Here, we discuss a novel signaling role for telomeric RNAs in cell fate and early development. Telomere checkpoint ensures genome stability in multicellular organisms but aggravates the aging process, promoting the accumulation of damaged and senescent cells.
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Affiliation(s)
- Alla Kalmykova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
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13
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Wu D, Dean J. Reduced female fertility due to sequestration of RNA Pol II by pervasive transcription in exosome RNase-depleted oocytes. Cell Rep 2023; 42:113247. [PMID: 37831603 DOI: 10.1016/j.celrep.2023.113247] [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: 02/16/2023] [Revised: 08/04/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023] Open
Abstract
Perturbing the transcriptome of mammalian oocytes results in meiotic failure. We previously reported that RNA-exosome-associated RNase, EXOSC10, degrades unwanted protein-coding RNA and processes ribosomal RNA to ensure proper oocyte maturation. Here, we establish oocyte-specific knockout mice of another RNA-exosome-associated RNase, DIS3. Mutant females (Dis3cKO) exhibit significantly reduced fertility because oocytes arrest after the growth phase. Single-oocyte RNA sequencing (RNA-seq) and CUT&Tag analyses show that DIS3 degrades intergenic RNA and mediates transcription silencing that is essential for chromatin condensation and resumption of meiosis. Dis3cKO oocytes exhibit elevated H3K27me3 in a pre-defined manner due to insufficient demethylation. During oocyte growth, EXOSC10 functions with DIS3 to degrade intergenic RNA. Double-knockout oocytes have earlier growth defects and more accumulated transcripts. We conclude that RNA exosomes synergistically degrade unwanted RNA and mediate transcription termination to ensure transcriptome integrity during oocyte development.
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Affiliation(s)
- Di Wu
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jurrien Dean
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA.
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14
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Krishnan R, Lapierre M, Gautreau B, Nixon KCJ, El Ghamrasni S, Patel P, Hao J, Yerlici V, Guturi K, St-Germain J, Mateo F, Saad A, Algouneh A, Earnshaw R, Shili D, Seitova A, Miller J, Khosraviani N, Penn A, Ho B, Sanchez O, Hande MP, Masson JY, Brown G, Alaoui-Jamali M, Reynolds J, Arrowsmith C, Raught B, Pujana M, Mekhail K, Stewart G, Hakem A, Hakem R. RNF8 ubiquitylation of XRN2 facilitates R-loop resolution and restrains genomic instability in BRCA1 mutant cells. Nucleic Acids Res 2023; 51:10484-10505. [PMID: 37697435 PMCID: PMC10602868 DOI: 10.1093/nar/gkad733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/10/2023] [Accepted: 08/24/2023] [Indexed: 09/13/2023] Open
Abstract
Breast cancer linked with BRCA1/2 mutations commonly recur and resist current therapies, including PARP inhibitors. Given the lack of effective targeted therapies for BRCA1-mutant cancers, we sought to identify novel targets to selectively kill these cancers. Here, we report that loss of RNF8 significantly protects Brca1-mutant mice against mammary tumorigenesis. RNF8 deficiency in human BRCA1-mutant breast cancer cells was found to promote R-loop accumulation and replication fork instability, leading to increased DNA damage, senescence, and synthetic lethality. Mechanistically, RNF8 interacts with XRN2, which is crucial for transcription termination and R-loop resolution. We report that RNF8 ubiquitylates XRN2 to facilitate its recruitment to R-loop-prone genomic loci and that RNF8 deficiency in BRCA1-mutant breast cancer cells decreases XRN2 occupancy at R-loop-prone sites, thereby promoting R-loop accumulation, transcription-replication collisions, excessive genomic instability, and cancer cell death. Collectively, our work identifies a synthetic lethal interaction between RNF8 and BRCA1, which is mediated by a pathological accumulation of R-loops.
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Affiliation(s)
- Rehna Krishnan
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Mariah Lapierre
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Brandon Gautreau
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Kevin C J Nixon
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Samah El Ghamrasni
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Parasvi S Patel
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, Ontario M5G 1L7, Canada
| | - Jun Hao
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - V Talya Yerlici
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | - Jonathan St-Germain
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Francesca Mateo
- Program Against Cancer Therapeutic Resistance (ProCURE), Catalan Institute of Oncology (ICO), Bellvitge Institute for Biomedical Research (IDIBELL), L’Hospitalet del Llobregat, Barcelona 08908, Catalonia, Spain
| | - Amine Saad
- Segal Cancer Centre and Lady Davis Institute for Medical Research, Departments of Medicine and Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Arash Algouneh
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Rebecca Earnshaw
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Duan Shili
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Alma Seitova
- Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Joshua Miller
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Negin Khosraviani
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Adam Penn
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Brandon Ho
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Otto Sanchez
- Ontario Tech University, 2000 Simcoe Street North Oshawa, Ontario L1G 0C5, Canada
| | - M Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, Oncology Axis; Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, 9 McMahon, Québec City, Québec G1R 2J6, Canada
| | - Grant W Brown
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Moulay Alaoui-Jamali
- Segal Cancer Centre and Lady Davis Institute for Medical Research, Departments of Medicine and Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - John J Reynolds
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Cheryl Arrowsmith
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, Ontario M5G 1L7, Canada
- Structural Genomics Consortium, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
- Department of Medical Biophysics, University of Toronto, Ontario M5G 1L7, Canada
| | - Miguel A Pujana
- Program Against Cancer Therapeutic Resistance (ProCURE), Catalan Institute of Oncology (ICO), Bellvitge Institute for Biomedical Research (IDIBELL), L’Hospitalet del Llobregat, Barcelona 08908, Catalonia, Spain
| | - Karim Mekhail
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Grant S Stewart
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Anne Hakem
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
| | - Razqallah Hakem
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario M5G 1L7, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Department of Medical Biophysics, University of Toronto, Ontario M5G 1L7, Canada
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15
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Li F, Zafar A, Luo L, Denning AM, Gu J, Bennett A, Yuan F, Zhang Y. R-Loops in Genome Instability and Cancer. Cancers (Basel) 2023; 15:4986. [PMID: 37894353 PMCID: PMC10605827 DOI: 10.3390/cancers15204986] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 10/04/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
R-loops are unique, three-stranded nucleic acid structures that primarily form when an RNA molecule displaces one DNA strand and anneals to the complementary DNA strand in a double-stranded DNA molecule. R-loop formation can occur during natural processes, such as transcription, in which the nascent RNA molecule remains hybridized with the template DNA strand, while the non-template DNA strand is displaced. However, R-loops can also arise due to many non-natural processes, including DNA damage, dysregulation of RNA degradation pathways, and defects in RNA processing. Despite their prevalence throughout the whole genome, R-loops are predominantly found in actively transcribed gene regions, enabling R-loops to serve seemingly controversial roles. On one hand, the pathological accumulation of R-loops contributes to genome instability, a hallmark of cancer development that plays a role in tumorigenesis, cancer progression, and therapeutic resistance. On the other hand, R-loops play critical roles in regulating essential processes, such as gene expression, chromatin organization, class-switch recombination, mitochondrial DNA replication, and DNA repair. In this review, we summarize discoveries related to the formation, suppression, and removal of R-loops and their influence on genome instability, DNA repair, and oncogenic events. We have also discussed therapeutical opportunities by targeting pathological R-loops.
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Affiliation(s)
- Fang Li
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Alyan Zafar
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Liang Luo
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Ariana Maria Denning
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Jun Gu
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Ansley Bennett
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Fenghua Yuan
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Yanbin Zhang
- Department of Biochemistry & Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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16
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Lim G, Hwang S, Yu K, Kang JY, Kang C, Hohng S. Translocating RNA polymerase generates R-loops at DNA double-strand breaks without any additional factors. Nucleic Acids Res 2023; 51:9838-9848. [PMID: 37638763 PMCID: PMC10570047 DOI: 10.1093/nar/gkad689] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 08/03/2023] [Accepted: 08/10/2023] [Indexed: 08/29/2023] Open
Abstract
The R-loops forming around DNA double-strand breaks (DSBs) within actively transcribed genes play a critical role in the DSB repair process. However, the mechanisms underlying R-loop formation at DSBs remain poorly understood, with diverse proposed models involving protein factors associated with RNA polymerase (RNAP) loading, pausing/backtracking or preexisting transcript RNA invasion. In this single-molecule study using Escherichia coli RNAP, we discovered that transcribing RNAP alone acts as a highly effective DSB sensor, responsible for generation of R-loops upon encountering downstream DSBs, without requiring any additional factors. The R-loop formation efficiency is greatly influenced by DNA end structures, ranging here from 2.8% to 73%, and notably higher on sticky ends with 3' or 5' single-stranded overhangs compared to blunt ends without any overhangs. The R-loops extend unidirectionally upstream from the DSB sites and can reach the transcription start site, interfering with ongoing-round transcription. Furthermore, the extended R-loops can persist and maintain their structures, effectively preventing the efficient initiation of subsequent transcription rounds. Our results are consistent with the bubble extension model rather than the 5'-end invasion model or the middle insertion model. These discoveries provide valuable insights into the initiation of DSB repair on transcription templates across bacteria, archaea and eukaryotes.
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Affiliation(s)
- Gunhyoung Lim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Seungha Hwang
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Kilwon Yu
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Jin Young Kang
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Changwon Kang
- Department of Biological Sciences, and KAIST Stem Cell Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Sungchul Hohng
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
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17
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Huang Y, Liu Y, Guo X, Fan C, Yi C, Shi Q, Su H, Liu C, Yuan J, Liu D, Yang W, Han F. New insights on the evolution of nucleolar dominance in newly resynthesized hexaploid wheat Triticum zhukovskyi. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:1298-1315. [PMID: 37246611 DOI: 10.1111/tpj.16320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/11/2023] [Accepted: 05/23/2023] [Indexed: 05/30/2023]
Abstract
Nucleolar dominance (ND) is a widespread epigenetic phenomenon in hybridizations where nucleolus transcription fails at the nucleolus organizer region (NOR). However, the dynamics of NORs during the formation of Triticum zhukovskyi (GGAu Au Am Am ), another evolutionary branch of allohexaploid wheat, remains poorly understood. Here, we elucidated genetic and epigenetic changes occurring at the NOR loci within the Am , G, and D subgenomes during allopolyploidization by synthesizing hexaploid wheat GGAu Au Am Am and GGAu Au DD. In T. zhukovskyi, Au genome NORs from T. timopheevii (GGAu Au ) were lost, while the second incoming NORs from T. monococcum (Am Am ) were retained. Analysis of the synthesized T. zhukovskyi revealed that rRNA genes from the Am genome were silenced in F1 hybrids (GAu Am ) and remained inactive after genome doubling and subsequent self-pollinations. We observed increased DNA methylation accompanying the inactivation of NORs in the Am genome and found that silencing of NORs in the S1 generation could be reversed by a cytidine methylase inhibitor. Our findings provide insights into the ND process during the evolutionary period of T. zhukovskyi and highlight that inactive rDNA units may serve as a 'first reserve' in the form of R-loops, contributing to the successful evolution of T. zhukovskyi.
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Affiliation(s)
- Yuhong Huang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xianrui Guo
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chaolan Fan
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Congyang Yi
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qinghua Shi
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Handong Su
- Huazhong Agricultural University, Hubei, 430070, China
| | - Chang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jing Yuan
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Dengcai Liu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
| | - Wuyun Yang
- Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, China
| | - Fangpu Han
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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18
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Patrasso EA, Raikundalia S, Arango D. Regulation of the epigenome through RNA modifications. Chromosoma 2023; 132:231-246. [PMID: 37138119 PMCID: PMC10524150 DOI: 10.1007/s00412-023-00794-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/10/2023] [Accepted: 04/12/2023] [Indexed: 05/05/2023]
Abstract
Chemical modifications of nucleotides expand the complexity and functional properties of genomes and transcriptomes. A handful of modifications in DNA bases are part of the epigenome, wherein DNA methylation regulates chromatin structure, transcription, and co-transcriptional RNA processing. In contrast, more than 150 chemical modifications of RNA constitute the epitranscriptome. Ribonucleoside modifications comprise a diverse repertoire of chemical groups, including methylation, acetylation, deamination, isomerization, and oxidation. Such RNA modifications regulate all steps of RNA metabolism, including folding, processing, stability, transport, translation, and RNA's intermolecular interactions. Initially thought to influence all aspects of the post-transcriptional regulation of gene expression exclusively, recent findings uncovered a crosstalk between the epitranscriptome and the epigenome. In other words, RNA modifications feedback to the epigenome to transcriptionally regulate gene expression. The epitranscriptome achieves this feat by directly or indirectly affecting chromatin structure and nuclear organization. This review highlights how chemical modifications in chromatin-associated RNAs (caRNAs) and messenger RNAs (mRNAs) encoding factors involved in transcription, chromatin structure, histone modifications, and nuclear organization affect gene expression transcriptionally.
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Affiliation(s)
- Emmely A Patrasso
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Medical and Pharmaceutical Biotechnology Program, IMC University of Applied Sciences, Krems, Austria
| | - Sweta Raikundalia
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Daniel Arango
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA.
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19
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Templeton CW, Laimins LA. p53-dependent R-loop formation and HPV pathogenesis. Proc Natl Acad Sci U S A 2023; 120:e2305907120. [PMID: 37611058 PMCID: PMC10467572 DOI: 10.1073/pnas.2305907120] [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: 04/12/2023] [Accepted: 06/30/2023] [Indexed: 08/25/2023] Open
Abstract
R-loops are trimeric RNA: DNA hybrids that are important physiological regulators of transcription; however, their aberrant formation or turnover leads to genomic instability and DNA breaks. High-risk human papillomaviruses (HPV) are the causative agents of genital as well as oropharyngeal cancers and exhibit enhanced amounts of DNA breaks. The levels of R-loops were found to be increased up to 50-fold in cells that maintain high-risk HPV genomes and were readily detected in squamous cell cervical carcinomas in vivo but not in normal cells. The high levels of R-loops in HPV-positive cells were present on both viral and cellular sites together with RNase H1, an enzyme that controls their resolution. Depletion of RNase H1 in HPV-positive cells further increased R-loop levels, resulting in impaired viral transcription and replication along with reduced expression of the DNA repair genes such as FANCD2 and ATR, both of which are necessary for viral functions. Overexpression of RNase H1 decreased total R-loop levels, resulting in a reduction of DNA breaks by over 50%. Furthermore, increased RNase H1 expression blocked viral transcription and replication while enhancing the expression of factors in the innate immune regulatory pathway. This suggests that maintaining elevated R-loop levels is important for the HPV life cycle. The E6 viral oncoprotein was found to be responsible for inducing high levels of R-loops by inhibiting p53's transcriptional activity. Our studies indicate that high R-loop levels are critical for HPV pathogenesis and that this depends on suppressing the p53 pathway.
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Affiliation(s)
- Conor Winslow Templeton
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Laimonis A. Laimins
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
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20
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Tschage L, Kowarz E, Marschalek R. Model System to Analyze RNA-Mediated DNA Repair in Mammalian Cells. CRISPR J 2023. [PMID: 37200486 DOI: 10.1089/crispr.2022.0105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023] Open
Abstract
"RNA-templated/directed DNA repair" is a biological mechanism that has been experimentally demonstrated in bacteria, yeast, and mammalian cells. Recent study has shown that small noncoding RNAs (DDRNAs) and/or newly RNAPII transcribed RNAs (dilncRNAs) are orchestrating the initial steps of double-strand break (DSB) repair. In this study, we demonstrate that also pre-mRNA could be used as direct or indirect substrate for DSB repair. Our test system is based on (1) a stably integrated mutant reporter gene that produces constitutively a nonspliceable pre-mRNA, (2) a transiently expressed sgRNA-guided dCas13b::ADAR fusion protein to specifically RNA edit the nonspliceable pre-mRNA, and (3) transiently expressed I-SceI to create a DSB situation to study the effect of spliceable pre-mRNA on DNA repair. Based on our data, the RNA-edited pre-mRNA was used in cis for the DSB repair process, thereby converting the genomically encoded mutant reporter gene into an active reporter gene. Overexpression and knockdown of several cellular proteins were performed to delineate their role in this novel "RNA-mediated end joining" pathway.
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Affiliation(s)
- Lisa Tschage
- Institute of Pharmaceutical Biology, Goethe-University, Frankfurt am Main, Germany
| | - Eric Kowarz
- Institute of Pharmaceutical Biology, Goethe-University, Frankfurt am Main, Germany
| | - Rolf Marschalek
- Institute of Pharmaceutical Biology, Goethe-University, Frankfurt am Main, Germany
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21
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Gong Y, Liu Y. R-Loops at Chromosome Ends: From Formation, Regulation, and Cellular Consequence. Cancers (Basel) 2023; 15:cancers15072178. [PMID: 37046839 PMCID: PMC10093737 DOI: 10.3390/cancers15072178] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 04/14/2023] Open
Abstract
Telomeric repeat containing RNA (TERRA) is transcribed from subtelomeric regions to telomeres. TERRA RNA can invade telomeric dsDNA and form telomeric R-loop structures. A growing body of evidence suggests that TERRA-mediated R-loops are critical players in telomere length homeostasis. Here, we will review current knowledge on the regulation of R-loop levels at telomeres. In particular, we will discuss how the central player TERRA and its binding proteins modulate R-loop levels through various mechanisms. We will further provide an overview of the consequences of TERRA-mediated persistent or unscheduled R-loops at telomeres in human ALT cancers and other organisms, with a focus on telomere length regulation after replication interference-induced damage and DNA homologous recombination-mediated repair.
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Affiliation(s)
- Yi Gong
- Laboratory of Genetics and Genomics, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
| | - Yie Liu
- Laboratory of Genetics and Genomics, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21224, USA
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22
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Laspata N, Kaur P, Mersaoui S, Muoio D, Liu Z, Bannister MH, Nguyen H, Curry C, Pascal J, Poirier G, Wang H, Masson JY, Fouquerel E. PARP1 associates with R-loops to promote their resolution and genome stability. Nucleic Acids Res 2023; 51:2215-2237. [PMID: 36794853 PMCID: PMC10018367 DOI: 10.1093/nar/gkad066] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 01/19/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023] Open
Abstract
PARP1 is a DNA-dependent ADP-Ribose transferase with ADP-ribosylation activity that is triggered by DNA breaks and non-B DNA structures to mediate their resolution. PARP1 was also recently identified as a component of the R-loop-associated protein-protein interaction network, suggesting a potential role for PARP1 in resolving this structure. R-loops are three-stranded nucleic acid structures that consist of a RNA-DNA hybrid and a displaced non-template DNA strand. R-loops are involved in crucial physiological processes but can also be a source of genome instability if persistently unresolved. In this study, we demonstrate that PARP1 binds R-loops in vitro and associates with R-loop formation sites in cells which activates its ADP-ribosylation activity. Conversely, PARP1 inhibition or genetic depletion causes an accumulation of unresolved R-loops which promotes genomic instability. Our study reveals that PARP1 is a novel sensor for R-loops and highlights that PARP1 is a suppressor of R-loop-associated genomic instability.
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Affiliation(s)
- Natalie Laspata
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA 15213, USA
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Parminder Kaur
- Physics Department, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, Raleigh, NC 27695, USA
| | - Sofiane Yacine Mersaoui
- CHU de Québec Research Centre, HDQ Pavilion, Oncology Division, Laval University Cancer Research Center, McMahon, Québec City, Québec G1R 3S3, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Quebec, Canada
| | - Daniela Muoio
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA 15213, USA
| | - Zhiyan Silvia Liu
- Department of Pharmacology, The Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Maxwell Henry Bannister
- Department of Pharmacology, The Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Hai Dang Nguyen
- Department of Pharmacology, The Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Caroline Curry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - John M Pascal
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Guy G Poirier
- Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Quebec, Canada
- CHU de Québec Research Centre, CHUL Pavilion, Oncology Division, Quebec, Canada
| | - Hong Wang
- Physics Department, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, Raleigh, NC 27695, USA
- Toxicology Program, North Carolina State University, Raleigh, NC, USA
| | - Jean-Yves Masson
- CHU de Québec Research Centre, HDQ Pavilion, Oncology Division, Laval University Cancer Research Center, McMahon, Québec City, Québec G1R 3S3, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Université Laval, Quebec, Canada
| | - Elise Fouquerel
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA 15213, USA
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23
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Moeckel C, Zaravinos A, Georgakopoulos-Soares I. Strand Asymmetries Across Genomic Processes. Comput Struct Biotechnol J 2023; 21:2036-2047. [PMID: 36968020 PMCID: PMC10030826 DOI: 10.1016/j.csbj.2023.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/08/2023] [Accepted: 03/08/2023] [Indexed: 03/12/2023] Open
Abstract
Across biological systems, a number of genomic processes, including transcription, replication, DNA repair, and transcription factor binding, display intrinsic directionalities. These directionalities are reflected in the asymmetric distribution of nucleotides, motifs, genes, transposon integration sites, and other functional elements across the two complementary strands. Strand asymmetries, including GC skews and mutational biases, have shaped the nucleotide composition of diverse organisms. The investigation of strand asymmetries often serves as a method to understand underlying biological mechanisms, including protein binding preferences, transcription factor interactions, retrotransposition, DNA damage and repair preferences, transcription-replication collisions, and mutagenesis mechanisms. Research into this subject also enables the identification of functional genomic sites, such as replication origins and transcription start sites. Improvements in our ability to detect and quantify DNA strand asymmetries will provide insights into diverse functionalities of the genome, the contribution of different mutational mechanisms in germline and somatic mutagenesis, and our knowledge of genome instability and evolution, which all have significant clinical implications in human disease, including cancer. In this review, we describe key developments that have been made across the field of genomic strand asymmetries, as well as the discovery of associated mechanisms.
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Affiliation(s)
- Camille Moeckel
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Apostolos Zaravinos
- Department of Life Sciences, European University Cyprus, Diogenis Str., 6, Nicosia 2404, Cyprus
- Cancer Genetics, Genomics and Systems Biology laboratory, Basic and Translational Cancer Research Center (BTCRC), Nicosia 1516, Cyprus
- Corresponding author at: Department of Life Sciences, European University Cyprus, Diogenis Str., 6, Nicosia 2404, Cyprus.
| | - Ilias Georgakopoulos-Soares
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
- Corresponding author.
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24
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Emerging role for R-loop formation in hepatocellular carcinoma. Genes Genomics 2023; 45:543-551. [PMID: 36635460 DOI: 10.1007/s13258-022-01360-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023]
Abstract
The pathophysiological characteristics of hepatocellular carcinoma (HCC) is closely associated with genomic instability. Genomic instability has long been considered to be a hallmark of both human genetic disease and cancers. It is now well accepted that regulating R-loop formation to minimized levels is one of critical modulation to maintain genome integrity, and that improper regulation of R-loop metabolism causes genomic instability via DNA breakage, ultimately resulting in replicative senescence and even tumorigenesis. Given that R-loop is natural by-product formed during normal transcription condition, and that several types of cancer have defense mechanism against the genomic instability resulted from R-loop formation, modulating functional implication of proteins involved in the intrinsic and specific mechanisms of abnormal R-loop formation in cancers therefore could play an important part in appropriated therapeutic strategies for HCC cohorts. In this review, we highlight the latest understanding on how R-loops promote genomic instability and address how alterations in these pathways link to human HCC.
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25
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Wong GCN, Chow KHM. DNA Damage Response-Associated Cell Cycle Re-Entry and Neuronal Senescence in Brain Aging and Alzheimer's Disease. J Alzheimers Dis 2023; 94:S429-S451. [PMID: 35848025 PMCID: PMC10473156 DOI: 10.3233/jad-220203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2022] [Indexed: 11/15/2022]
Abstract
Chronological aging is by far the strongest risk factor for age-related dementia and Alzheimer's disease. Senescent cells accumulated in the aging and Alzheimer's disease brains are now recognized as the keys to describing such an association. Cellular senescence is a classic phenomenon characterized by stable cell arrest, which is thought to be applicable only to dividing cells. Emerging evidence indicates that fully differentiated post-mitotic neurons are also capable of becoming senescent, with roles in contributing to both brain aging and disease pathogenesis. The key question that arises is the identity of the upstream triggers and the molecular mechanisms that underly such changes. Here, we highlight the potential role of persistent DNA damage response as the major driver of senescent phenotypes and discuss the current evidence and molecular mechanisms that connect DNA repair infidelity, cell cycle re-entry and terminal fate decision in committing neuronal cell senescence.
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Affiliation(s)
- Genper Chi-Ngai Wong
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong
| | - Kim Hei-Man Chow
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong
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26
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Brown RE, Su XA, Fair S, Wu K, Verra L, Jong R, Andrykovich K, Freudenreich CH. The RNA export and RNA decay complexes THO and TRAMP prevent transcription-replication conflicts, DNA breaks, and CAG repeat contractions. PLoS Biol 2022; 20:e3001940. [PMID: 36574440 PMCID: PMC9829180 DOI: 10.1371/journal.pbio.3001940] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/09/2023] [Accepted: 12/01/2022] [Indexed: 12/28/2022] Open
Abstract
Expansion of structure-forming CAG/CTG repetitive sequences is the cause of several neurodegenerative disorders and deletion of repeats is a potential therapeutic strategy. Transcription-associated mechanisms are known to cause CAG repeat instability. In this study, we discovered that Thp2, an RNA export factor and member of the THO (suppressors of transcriptional defects of hpr1Δ by overexpression) complex, and Trf4, a key component of the TRAMP (Trf4/5-Air1/2-Mtr4 polyadenylation) complex involved in nuclear RNA polyadenylation and degradation, are necessary to prevent CAG fragility and repeat contractions in a Saccharomyces cerevisiae model system. Depletion of both Thp2 and Trf4 proteins causes a highly synergistic increase in CAG repeat fragility, indicating a complementary role of the THO and TRAMP complexes in preventing genome instability. Loss of either Thp2 or Trf4 causes an increase in RNA polymerase stalling at the CAG repeats and other genomic loci, as well as genome-wide transcription-replication conflicts (TRCs), implicating TRCs as a cause of CAG fragility and instability in their absence. Analysis of the effect of RNase H1 overexpression on CAG fragility, RNAPII stalling, and TRCs suggests that RNAPII stalling with associated R-loops are the main cause of CAG fragility in the thp2Δ mutants. In contrast, CAG fragility and TRCs in the trf4Δ mutant can be compensated for by RPA overexpression, suggesting that excess unprocessed RNA in TRAMP4 mutants leads to reduced RPA availability and high levels of TRCs. Our results show the importance of RNA surveillance pathways in preventing RNAPII stalling, TRCs, and DNA breaks, and show that RNA export and RNA decay factors work collaboratively to maintain genome stability.
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Affiliation(s)
- Rebecca E. Brown
- Program in Genetics, Tufts University School of Graduate Biomedical Sciences, Boston, Massachusetts, United States of America
| | - Xiaofeng A. Su
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
- David H. Koch Institute for Integrative Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Stacey Fair
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Katherine Wu
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Lauren Verra
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Robyn Jong
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Kristin Andrykovich
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
| | - Catherine H. Freudenreich
- Program in Genetics, Tufts University School of Graduate Biomedical Sciences, Boston, Massachusetts, United States of America
- Department of Biology, Tufts University, Medford, Massachusetts, United States of America
- * E-mail:
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27
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Khan ES, Danckwardt S. Pathophysiological Role and Diagnostic Potential of R-Loops in Cancer and Beyond. Genes (Basel) 2022; 13:genes13122181. [PMID: 36553448 PMCID: PMC9777984 DOI: 10.3390/genes13122181] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/07/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022] Open
Abstract
R-loops are DNA-RNA hybrids that play multifunctional roles in gene regulation, including replication, transcription, transcription-replication collision, epigenetics, and preserving the integrity of the genome. The aberrant formation and accumulation of unscheduled R-loops can disrupt gene expression and damage DNA, thereby causing genome instability. Recent links between unscheduled R-loop accumulation and the abundance of proteins that modulate R-loop biogenesis have been associated with numerous human diseases, including various cancers. Although R-loops are not necessarily causative for all disease entities described to date, they can perpetuate and even exacerbate the initially disease-eliciting pathophysiology, making them structures of interest for molecular diagnostics. In this review, we discuss the (patho) physiological role of R-loops in health and disease, their surprising diagnostic potential, and state-of-the-art techniques for their detection.
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Affiliation(s)
- Essak S. Khan
- Posttranscriptional Gene Regulation, Cancer Research and Experimental Hemostasis, University Medical Center Mainz, 55131 Mainz, Germany
- Institute for Clinical Chemistry and Laboratory Medicine, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- German Consortium for Translational Cancer Research (DKTK), DKFZ Frankfurt-Mainz, 60590 Frankfurt am Main, Germany
| | - Sven Danckwardt
- Posttranscriptional Gene Regulation, Cancer Research and Experimental Hemostasis, University Medical Center Mainz, 55131 Mainz, Germany
- Institute for Clinical Chemistry and Laboratory Medicine, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
- German Center for Cardiovascular Research (DZHK), Rhine-Main, 55131 Mainz, Germany
- Correspondence:
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28
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Belotserkovskii BP, Hanawalt PC. Topology and kinetics of R-loop formation. Biophys J 2022; 121:3345-3357. [PMID: 36004778 PMCID: PMC9515371 DOI: 10.1016/j.bpj.2022.08.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/06/2022] [Accepted: 08/18/2022] [Indexed: 11/19/2022] Open
Abstract
R-loops are structures containing an RNA-DNA duplex and an unpaired DNA strand. They can be formed upon "invasion" of an RNA strand into a DNA duplex, during which the RNA displaces the homologous DNA strand and binds the complementary strand. R-loops have many significant beneficial or deleterious biological effects, so it is important to understand the mechanisms for their generation and processing. We propose a model for co-transcriptional R-loop formation, in which their generation requires passage of the nascent RNA "tail" through the gap between the separated DNA strands. This passage becomes increasingly difficult with lengthening of the RNA tail. The length of the tail increases upon increasing distance between the transcription start site and the site of R-loop initiation. This causes reduced yields of R-loops with greater distance from the transcription start site. However, alternative pathways for R-loop formation are possible, involving either transient disruption of the transcription complex or the hypothetical formation of a triple-stranded structure, as a "collapsed R-loop." These alternative pathways could account for the fact that in many systems R-loops are observed very far from the transcription start site. Our model is consistent with experimental data and makes general predictions about the kinetics of R-loop formation.
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29
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Bruno T, Corleone G, Catena V, Cortile C, De Nicola F, Fabretti F, Gumenyuk S, Pisani F, Mengarelli A, Passananti C, Fanciulli M. AATF/Che-1 localizes to paraspeckles and suppresses R-loops accumulation and interferon activation in Multiple Myeloma. EMBO J 2022; 41:e109711. [PMID: 35929179 PMCID: PMC9670196 DOI: 10.15252/embj.2021109711] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 07/06/2022] [Accepted: 07/14/2022] [Indexed: 01/13/2023] Open
Abstract
Several kinds of stress promote the formation of three-stranded RNA:DNA hybrids called R-loops. Insufficient clearance of these structures promotes genomic instability and DNA damage, which ultimately contribute to the establishment of cancer phenotypes. Paraspeckle assemblies participate in R-loop resolution and preserve genome stability, however, the main determinants of this mechanism are still unknown. This study finds that in Multiple Myeloma (MM), AATF/Che-1 (Che-1), an RNA-binding protein fundamental to transcription regulation, interacts with paraspeckles via the lncRNA NEAT1_2 (NEAT1) and directly localizes on R-loops. We systematically show that depletion of Che-1 produces a marked accumulation of RNA:DNA hybrids. We provide evidence that such failure to resolve R-loops causes sustained activation of a systemic inflammatory response characterized by an interferon (IFN) gene expression signature. Furthermore, elevated levels of R-loops and of mRNA for paraspeckle genes in patient cells are linearly correlated with Multiple Myeloma progression. Moreover, increased interferon gene expression signature in patients is associated with markedly poor prognosis. Taken together, our study indicates that Che-1/NEAT1 cooperation prevents excessive inflammatory signaling in Multiple Myeloma by facilitating the clearance of R-loops. Further studies on different cancer types are needed to test if this mechanism is ubiquitously conserved and fundamental for cell homeostasis.
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Affiliation(s)
- Tiziana Bruno
- SAFU Laboratory, Department of Research, Advanced Diagnostics, and Technological Innovation, Translational Research AreaIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Giacomo Corleone
- SAFU Laboratory, Department of Research, Advanced Diagnostics, and Technological Innovation, Translational Research AreaIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Valeria Catena
- SAFU Laboratory, Department of Research, Advanced Diagnostics, and Technological Innovation, Translational Research AreaIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Clelia Cortile
- SAFU Laboratory, Department of Research, Advanced Diagnostics, and Technological Innovation, Translational Research AreaIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Francesca De Nicola
- SAFU Laboratory, Department of Research, Advanced Diagnostics, and Technological Innovation, Translational Research AreaIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Francesca Fabretti
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine and University Hospital of CologneUniversity of CologneCologneGermany,Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Svitlana Gumenyuk
- Hematology UnitIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Francesco Pisani
- Hematology UnitIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Andrea Mengarelli
- Hematology UnitIRCCS Regina Elena National Cancer InstituteRomeItaly
| | - Claudio Passananti
- Department of Molecular Medicine, CNR‐Institute of Molecular Biology and PathologySapienza University of RomeRomeItaly
| | - Maurizio Fanciulli
- SAFU Laboratory, Department of Research, Advanced Diagnostics, and Technological Innovation, Translational Research AreaIRCCS Regina Elena National Cancer InstituteRomeItaly
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30
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Donnio LM, Cerutti E, Magnani C, Neuillet D, Mari PO, Giglia-Mari G. XAB2 dynamics during DNA damage-dependent transcription inhibition. eLife 2022; 11:77094. [PMID: 35880862 PMCID: PMC9436415 DOI: 10.7554/elife.77094] [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: 01/25/2022] [Accepted: 07/25/2022] [Indexed: 11/25/2022] Open
Abstract
Xeroderma Pigmentosum group A-binding protein 2 (XAB2) is a multifunctional protein playing a critical role in distinct cellular processes including transcription, splicing, DNA repair, and messenger RNA export. In this study, we demonstrate that XAB2 is involved specifically and exclusively in Transcription-Coupled Nucleotide Excision Repair (TC-NER) reactions and solely for RNA polymerase 2 (RNAP2)-transcribed genes. Surprisingly, contrary to all the other NER proteins studied so far, XAB2 does not accumulate on the local UV-C damage; on the contrary, it becomes more mobile after damage induction. XAB2 mobility is restored when DNA repair reactions are completed. By scrutinizing from which cellular complex/partner/structure XAB2 is released, we have identified that XAB2 is detached after DNA damage induction from DNA:RNA hybrids, commonly known as R-loops, and from the CSA and XPG proteins. This release contributes to the DNA damage recognition step during TC-NER, as in the absence of XAB2, RNAP2 is blocked longer on UV lesions. Moreover, we also demonstrate that XAB2 has a role in retaining RNAP2 on its substrate without any DNA damage.
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Affiliation(s)
- Lise-Marie Donnio
- Institut NeuroMyogène (INMG), CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Elena Cerutti
- Institut NeuroMyogène (INMG), CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Charlene Magnani
- Institut NeuroMyogène (INMG), CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Damien Neuillet
- Institut NeuroMyogène (INMG), CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Pierre-Olivier Mari
- Institut NeuroMyogène (INMG), CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Giuseppina Giglia-Mari
- Institut NeuroMyogène (INMG), CNRS UMR 5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
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31
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Patel PS, Krishnan R, Hakem R. Emerging roles of DNA topoisomerases in the regulation of R-loops. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 876-877:503450. [PMID: 35483781 DOI: 10.1016/j.mrgentox.2022.503450] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 12/24/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
R-loops are comprised of a DNA:RNA hybrid and a displaced single-strand DNA (ssDNA) that reinvades the DNA duplex behind the moving RNA polymerase. Because they have several physiological functions within the cell, including gene expression, chromosomal segregation, and mitochondrial DNA replication, among others, R-loop homeostasis is tightly regulated to ensure normal functioning of cellular processes. Thus, several classes of enzymes including RNases, helicases, topoisomerases, as well as proteins involved in splicing and the biogenesis of messenger ribonucleoproteins, have been implicated in R-loop prevention, suppression, and resolution. There exist six topoisomerase enzymes encoded by the human genome that function to introduce transient DNA breaks to relax supercoiled DNA. In this mini-review, we discuss functions of DNA topoisomerases and their emerging role in transcription, replication, and regulation of R-loops, and we highlight how their role in maintaining genome stability can be exploited for cancer therapy.
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Affiliation(s)
- Parasvi S Patel
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1L7, Canada
| | - Rehna Krishnan
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
| | - Razqallah Hakem
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, M5G 1L7, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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32
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Chimeric RNA Design Principles for RNA-Mediated Gene Fusion. Cells 2022; 11:cells11061002. [PMID: 35326453 PMCID: PMC8947500 DOI: 10.3390/cells11061002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/07/2022] [Accepted: 03/14/2022] [Indexed: 12/02/2022] Open
Abstract
One common genetic alteration in cancer is gene fusion resulting from chromosomal translocations. The mechanisms that create such oncogenic fusion genes are not well understood. Previously, we provided the direct evidence that expression of a designed chimeric RNA can drive the formation of TMPRSS2-ERG gene fusion. Central to this RNA-mediated gene fusion mechanism is a proposed three-way junction formed by RNA/DNA hybrid and the intergenic DNA stem formed by target genes. In this study, we determined the important parameters for chimeric RNA-mediated gene fusion using TMPRSS2-ERG fusion gene as the model. Our results indicate that both the chimeric RNA lengths and the sizes of unpaired bulges play important roles in inducing TMPRSS2-ERG gene fusion. The optimal length of unpaired bulges was about 35 nt, while the optimal chimeric RNA length was about 50 nt for targeting. These observations were consistent regardless of the target locations within TMPRSS2 and ERG genes. These empirically determined parameters provide important insight for searching cellular RNAs that may initiate oncogenic fusion genes. The knowledge could also facilitate the development of useful genomic technology for manipulating mammalian genomes.
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33
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Pommier Y, Nussenzweig A, Takeda S, Austin C. Human topoisomerases and their roles in genome stability and organization. Nat Rev Mol Cell Biol 2022; 23:407-427. [PMID: 35228717 PMCID: PMC8883456 DOI: 10.1038/s41580-022-00452-3] [Citation(s) in RCA: 118] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
Human topoisomerases comprise a family of six enzymes: two type IB (TOP1 and mitochondrial TOP1 (TOP1MT), two type IIA (TOP2A and TOP2B) and two type IA (TOP3A and TOP3B) topoisomerases. In this Review, we discuss their biochemistry and their roles in transcription, DNA replication and chromatin remodelling, and highlight the recent progress made in understanding TOP3A and TOP3B. Because of recent advances in elucidating the high-order organization of the genome through chromatin loops and topologically associating domains (TADs), we integrate the functions of topoisomerases with genome organization. We also discuss the physiological and pathological formation of irreversible topoisomerase cleavage complexes (TOPccs) as they generate topoisomerase DNA–protein crosslinks (TOP-DPCs) coupled with DNA breaks. We discuss the expanding number of redundant pathways that repair TOP-DPCs, and the defects in those pathways, which are increasingly recognized as source of genomic damage leading to neurological diseases and cancer. Topoisomerases have essential roles in transcription, DNA replication, chromatin remodelling and, as recently revealed, 3D genome organization. However, topoisomerases also generate DNA–protein crosslinks coupled with DNA breaks, which are increasingly recognized as a source of disease-causing genomic damage.
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34
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Mechanism for R-loop formation remote from the transcription start site: Topological issues and possible facilitation by dissociation of RNA polymerase. DNA Repair (Amst) 2022; 110:103275. [DOI: 10.1016/j.dnarep.2022.103275] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 11/18/2022]
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Jauregui‐Lozano J, Escobedo S, Easton A, Lanman N, Weake VM, Hall H. Proper control of R-loop homeostasis is required for maintenance of gene expression and neuronal function during aging. Aging Cell 2022; 21:e13554. [PMID: 35048512 PMCID: PMC8844117 DOI: 10.1111/acel.13554] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/03/2021] [Accepted: 01/03/2022] [Indexed: 01/25/2023] Open
Abstract
Age‐related loss of cellular function and increased cell death are characteristic hallmarks of aging. While defects in gene expression and RNA metabolism have been linked with age‐associated human neuropathies, it is not clear how the changes that occur in aging neurons contribute to loss of gene expression homeostasis. R‐loops are RNA–DNA hybrids that typically form co‐transcriptionally via annealing of the nascent RNA to the template DNA strand, displacing the non‐template DNA strand. Dysregulation of R‐loop homeostasis has been associated with both transcriptional impairment and genome instability. Importantly, a growing body of evidence links R‐loop accumulation with cellular dysfunction, increased cell death, and chronic disease onset. Here, we characterized the R‐loop landscape in aging Drosophila melanogaster photoreceptor neurons and showed that bulk R‐loop levels increased with age. Further, genome‐wide mapping of R‐loops revealed that transcribed genes accumulated R‐loops over gene bodies during aging, which correlated with decreased expression of long and highly expressed genes. Importantly, while photoreceptor‐specific down‐regulation of Top3β, a DNA/RNA topoisomerase associated with R‐loop resolution, lead to decreased visual function, over‐expression of Top3β or nuclear‐localized RNase H1, which resolves R‐loops, enhanced positive light response during aging. Together, our studies highlight the functional link between dysregulation of R‐loop homeostasis, gene expression, and visual function during aging.
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Affiliation(s)
| | - Spencer Escobedo
- Department of Biochemistry Purdue University West Lafayette Indiana USA
| | - Alyssa Easton
- Department of Agricultural and Biological Engineering Purdue University West Lafayette Indiana USA
| | - Nadia A. Lanman
- Department of Comparative Pathobiology College of Veterinary Medicine Purdue University West Lafayette Indiana USA
- Purdue University Center for Cancer Research Purdue University West Lafayette Indiana USA
| | - Vikki M. Weake
- Department of Biochemistry Purdue University West Lafayette Indiana USA
- Purdue University Center for Cancer Research Purdue University West Lafayette Indiana USA
| | - Hana Hall
- Department of Biochemistry Purdue University West Lafayette Indiana USA
- Purdue Institute for Integrative Neuroscience Purdue University West Lafayette Indiana USA
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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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Malina J, Kostrhunova H, Brabec V. Dinuclear nickel( ii) supramolecular helicates down-regulate gene expression in human cells by stabilizing DNA G-quadruplexes formed in the promoter regions. Inorg Chem Front 2022. [DOI: 10.1039/d2qi01435a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dinuclear nickel(ii) supramolecular helicates selectively stabilize DNA G-quadruplexes and suppress G-quadruplex-regulated genes.
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Affiliation(s)
- Jaroslav Malina
- Czech Academy of Sciences, Institute of Biophysics, Kralovopolska 135, CZ-61265 Brno, Czech Republic
| | - Hana Kostrhunova
- Czech Academy of Sciences, Institute of Biophysics, Kralovopolska 135, CZ-61265 Brno, Czech Republic
| | - Viktor Brabec
- Czech Academy of Sciences, Institute of Biophysics, Kralovopolska 135, CZ-61265 Brno, Czech Republic
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38
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Zhang X, Hao Y, Fu XD. Mapping R-Loops Using Catalytically Inactive RNaseH1 (R-ChIP). Methods Mol Biol 2022; 2528:359-372. [PMID: 35704204 DOI: 10.1007/978-1-0716-2477-7_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
R-loops, three-stranded structures containing double-stranded DNA invaded by single-stranded RNA, have been linked to diverse biological processes. They play important roles in regulating gene regulation and DNA repair, contributing to a wide range of diseases. Understanding the formation and dynamic regulation of R-loops is thus a gateway to address many fundamental questions in regulatory biology, which requires the elucidation of the R-loop landscape at the genome scale. To aid in such efforts, this article provides an overview on R-loop mapping strategies along with a detailed protocol based on the use of catalytically inactive RNaseH1, an evolutionarily conserved protein responsible for R-loop recognition and resolution.
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Affiliation(s)
- Xuan Zhang
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California San Diego, La Jolla, CA, USA
| | - Yajing Hao
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California San Diego, La Jolla, CA, USA
| | - Xiang-Dong Fu
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California San Diego, La Jolla, CA, USA.
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Botrugno OA, Tonon G. Genomic Instability and Replicative Stress in Multiple Myeloma: The Final Curtain? Cancers (Basel) 2021; 14:cancers14010025. [PMID: 35008191 PMCID: PMC8750813 DOI: 10.3390/cancers14010025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 12/02/2022] Open
Abstract
Simple Summary Genomic instability is recognized as a driving force in most cancers as well as in the haematological cancer multiple myeloma and remains among the leading cause of drug resistance. Several evidences suggest that replicative stress exerts a fundamental role in fuelling genomic instability. Notably, cancer cells rely on a single protein, ATR, to cope with the ensuing DNA damage. In this perspective, we provide an overview depicting how replicative stress represents an Achilles heel for multiple myeloma, which could be therapeutically exploited either alone or in combinatorial regimens to preferentially ablate tumor cells. Abstract Multiple Myeloma (MM) is a genetically complex and heterogeneous hematological cancer that remains incurable despite the introduction of novel therapies in the clinic. Sadly, despite efforts spanning several decades, genomic analysis has failed to identify shared genetic aberrations that could be targeted in this disease. Seeking alternative strategies, various efforts have attempted to target and exploit non-oncogene addictions of MM cells, including, for example, proteasome inhibitors. The surprising finding that MM cells present rampant genomic instability has ignited concerted efforts to understand its origin and exploit it for therapeutic purposes. A credible hypothesis, supported by several lines of evidence, suggests that at the root of this phenotype there is intense replicative stress. Here, we review the current understanding of the role of replicative stress in eliciting genomic instability in MM and how MM cells rely on a single protein, Ataxia Telangiectasia-mutated and Rad3-related protein, ATR, to control and survive the ensuing, potentially fatal DNA damage. From this perspective, replicative stress per se represents not only an opportunity for MM cells to increase their evolutionary pool by increasing their genomic heterogeneity, but also a vulnerability that could be leveraged for therapeutic purposes to selectively target MM tumor cells.
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Affiliation(s)
- Oronza A. Botrugno
- Functional Genomics of Cancer Unit, Experimental Oncology Division, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Correspondence: (O.A.B.); (G.T.); Tel.: +39-02-2643-6661 (O.A.B.); +39-02-2643-5624 (G.T.); Fax: +39-02-2643-6352 (O.A.B. & G.T.)
| | - Giovanni Tonon
- Functional Genomics of Cancer Unit, Experimental Oncology Division, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Center for Omics Sciences, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy
- Correspondence: (O.A.B.); (G.T.); Tel.: +39-02-2643-6661 (O.A.B.); +39-02-2643-5624 (G.T.); Fax: +39-02-2643-6352 (O.A.B. & G.T.)
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40
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Gupta SK, Jea JDY, Yen L. RNA-driven JAZF1-SUZ12 gene fusion in human endometrial stromal cells. PLoS Genet 2021; 17:e1009985. [PMID: 34928964 PMCID: PMC8722726 DOI: 10.1371/journal.pgen.1009985] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 01/03/2022] [Accepted: 12/08/2021] [Indexed: 12/17/2022] Open
Abstract
Oncogenic fusion genes as the result of chromosomal rearrangements are important for understanding genome instability in cancer cells and developing useful cancer therapies. To date, the mechanisms that create such oncogenic fusion genes are poorly understood. Previously we reported an unappreciated RNA-driven mechanism in human prostate cells in which the expression of chimeric RNA induces specified gene fusions in a sequence-dependent manner. One fundamental question yet to be addressed is whether such RNA-driven gene fusion mechanism is generalizable, or rather, a special case restricted to prostate cells. In this report, we demonstrated that the expression of designed chimeric RNAs in human endometrial stromal cells leads to the formation of JAZF1-SUZ12, a cancer fusion gene commonly found in low-grade endometrial stromal sarcomas. The process is specified by the sequence of chimeric RNA involved and inhibited by estrogen or progesterone. Furthermore, it is the antisense rather than sense chimeric RNAs that effectively drive JAZF1-SUZ12 gene fusion. The induced fusion gene is validated both at the RNA and the genomic DNA level. The ability of designed chimeric RNAs to drive and recapitulate the formation of JAZF1-SUZ12 gene fusion in endometrial cells represents another independent case of RNA-driven gene fusion, suggesting that RNA-driven genomic recombination is a permissible mechanism in mammalian cells. The results could have fundamental implications in the role of RNA in genome stability, and provide important insight in early disease mechanisms related to the formation of cancer fusion genes. Fusion genes resulting from chromosomal translocations are important for understanding cancer mechanisms and developing anti-cancer therapies. Fusion gene are presumed to occur prior to fusion RNA expression. However, studies have reported the presence of fusion RNAs in individuals who were negative for chromosomal translocations. The observation, that fusion RNA could be present prior to fusion gene formation, raises the provocative hypothesis that fusion RNA, or any cellular RNA with sequence compositions resembling that of fusion RNA, could act as a template to mediate genomic rearrangement which leads to the final gene fusion. In this report, we demonstrated that the expression of designed chimeric RNAs in human endometrial stromal cells leads to the formation of JAZF1-SUZ12, a cancer fusion gene found in endometrial stromal sarcomas. The process is specified by the sequence of chimeric RNA involved and inhibited by estrogen or progesterone. Furthermore, it is the antisense rather than sense chimeric RNAs that effectively drive JAZF1-SUZ12 gene fusion. The results could have fundamental implications in the role of RNA in mammalian genome stability, provide important insight in early disease mechanism, as well as developing gene editing technology via mechanisms native to mammalian cells.
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Affiliation(s)
- Sachin Kumar Gupta
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jocelyn Duen-Ya Jea
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Laising Yen
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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41
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Kwak YD, Shaw TI, Downing SM, Tewari A, Jin H, Li Y, Dumitrache LC, Katyal S, Khodakhah K, Russell HR, McKinnon PJ. Chromatin architecture at susceptible gene loci in cerebellar Purkinje cells characterizes DNA damage-induced neurodegeneration. SCIENCE ADVANCES 2021; 7:eabg6363. [PMID: 34910524 DOI: 10.1126/sciadv.abg6363] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The pathogenesis of inherited genome instability neurodegenerative syndromes remains largely unknown. Here, we report new disease-relevant murine models of genome instability–driven neurodegeneration involving disabled ATM and APTX that develop debilitating ataxia. We show that neurodegeneration and ataxia result from transcriptional interference in the cerebellum via aberrant messenger RNA splicing. Unexpectedly, these splicing defects were restricted to only Purkinje cells, disrupting the expression of critical homeostatic regulators including ITPR1, GRID2, and CA8. Abundant genotoxic R loops were also found at these Purkinje cell gene loci, further exacerbating DNA damage and transcriptional disruption. Using ATAC-seq to profile global chromatin accessibility in the cerebellum, we found a notably unique chromatin conformation specifically in Purkinje chromatin at the affected gene loci, thereby promoting susceptibility to DNA damage. These data reveal the pathogenic basis of DNA damage in the nervous system and suggest chromatin conformation as a feature in directing genome instability–associated neuropathology.
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Affiliation(s)
- Young Don Kwak
- Departments of Genetics and Cell Molecular Biology, Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, Memphis, TN 38105, USA
| | | | - Susanna M Downing
- Departments of Genetics and Cell Molecular Biology, Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, Memphis, TN 38105, USA
| | - Ambika Tewari
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Hongjian Jin
- Center for Applied Bioinformatics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yang Li
- Departments of Genetics and Cell Molecular Biology, Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, Memphis, TN 38105, USA
| | - Lavinia C Dumitrache
- Departments of Genetics and Cell Molecular Biology, Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, Memphis, TN 38105, USA
| | - Sachin Katyal
- CancerCare Manitoba Research Institute, CancerCare Manitoba and Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB R3E OV9, Canada
| | - Kamran Khodakhah
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Helen R Russell
- Departments of Genetics and Cell Molecular Biology, Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, Memphis, TN 38105, USA
| | - Peter J McKinnon
- Departments of Genetics and Cell Molecular Biology, Center for Pediatric Neurological Disease Research, St. Jude Pediatric Translational Neuroscience Initiative, Memphis, TN 38105, USA
- St. Jude Graduate School of Biomedical Sciences, Memphis, TN 38105, USA
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42
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Chen L, Xu W, Liu K, Jiang Z, Han Y, Jin H, Zhang L, Shen W, Jia S, Sun Q, Meng A. 5' Half of specific tRNAs feeds back to promote corresponding tRNA gene transcription in vertebrate embryos. SCIENCE ADVANCES 2021; 7:eabh0494. [PMID: 34797706 PMCID: PMC8604414 DOI: 10.1126/sciadv.abh0494] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
5′tRFls are small transfer RNA (tRNA) fragments derived from 5′ half of mature tRNAs. However, it is unknown whether 5′tRFls could feed back to regulate tRNA biogenesis. Here, we show that 5′tRFlGly/GCC and 5′tRFlGlu/CTC function to promote transcription of corresponding tRNA genes and are essential for vertebrate early embryogenesis. During zebrafish embryogenesis, dynamics of 5′tRFlGly/GCC and 5′tRFlGlu/CTC levels correlates with that of tRNAGly/GCC and tRNAGlu/CTC levels. Morpholino-mediated knockdown of 5′tRFlGly/GCC or 5′tRFlGlu/CTC down-regulates tRNAGly/GCC or tRNAGlu/CTC levels, respectively, and causes embryonic lethality that is efficiently rescued by coinjection of properly refolded corresponding tRNA. In zebrafish embryos, tRNA:DNA and 5′tRFl:DNA hybrids commonly exist on the template strand of tRNA genes. Mechanistically, unstable 5′tRFl:DNA hybrid may prevent the formation of transcriptionally inhibitory stable tRNA:DNA hybrids on the same tRNA loci so as to facilitate tRNA gene transcription. The uncovered mechanism may be implicated in other physiological and pathological processes.
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Affiliation(s)
- Luxi Chen
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wei Xu
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
- The Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Kunpeng Liu
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
- The Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zheng Jiang
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yang Han
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Hongbin Jin
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lin Zhang
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Weimin Shen
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shunji Jia
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qianwen Sun
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
- The Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anming Meng
- Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China
- Guangzhou Laboratory, Guangzhou 510320, Guangdong Province, China
- Corresponding author.
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43
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Li Y, Kardell MB, Wang F, Wang L, Zhu S, Bessho T, Peng A. The Sm core components of small nuclear ribonucleoproteins promote homologous recombination repair. DNA Repair (Amst) 2021; 108:103244. [PMID: 34768043 DOI: 10.1016/j.dnarep.2021.103244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 10/01/2021] [Accepted: 10/29/2021] [Indexed: 11/17/2022]
Abstract
DNA Double strand breaks (DSBs) are highly hazardous to the cell, and are repaired predominantly via non-homologous end joining (NHEJ) and homologous recombination (HR). Using DSB-mimicking DNA templates, our proteomic studies identified a group of Sm core proteins of small nuclear ribonucleoproteins (snRNPs) as potential DSB-associated proteins. We further confirmed that these Sm proteins were recruited to laser-induced DNA damage sites, and co-localized with established DNA damage repair factors. Depletion of Sm-D3 or Sm-B induced accumulation of γ-H2AX, and impaired the repair efficiency of HR, but not NHEJ. Furthermore, disruption of Sm-D3 reduced the protein level of HR factors, especially RAD51 and CHK1, but caused no change in the expression of repair factors involved in NHEJ. Mechanistically, Sm-D3 proteins bound RAD51, suppressed the ubiquitination of RAD51, and mediated the stabilization of RAD51; Sm-D3 depletion particularly impacted the level of RAD51 and CHK1 on damaged chromatin. As such, our studies characterized a role of Sm proteins in HR repair, via a new mechanism that is distinct from their conventional functions in RNA processing and gene regulation, but consistent with their direct recruitment to DNA damage sites and association with repair factors.
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Affiliation(s)
- Yanqiu Li
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, USA
| | - Mary Bridget Kardell
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, USA
| | - Feifei Wang
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, USA
| | - Ling Wang
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, USA
| | - Songli Zhu
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, USA
| | - Tadayoshi Bessho
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Aimin Peng
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, USA.
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44
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Busatto FF, Mersaoui SY, Sun Y, Pommier Y, Masson JY, Saffi J. Functions of the CSB Protein at Topoisomerase 2 Inhibitors-Induced DNA Lesions. Front Cell Dev Biol 2021; 9:727836. [PMID: 34746125 PMCID: PMC8569893 DOI: 10.3389/fcell.2021.727836] [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: 06/19/2021] [Accepted: 10/01/2021] [Indexed: 12/05/2022] Open
Abstract
Topoisomerase 2 (TOP2) inhibitors are drugs widely used in the treatment of different types of cancer. Processing of their induced-lesions create double-strand breaks (DSBs) in the DNA, which is the main toxic mechanism of topoisomerase inhibitors to kill cancer cells. It was established that the Nucleotide Excision Repair pathway respond to TOP2-induced lesions, mainly through the Cockayne Syndrome B (CSB) protein. In this paper, we further define the mechanism and type of lesions induced by TOP2 inhibitors when CSB is abrogated. In the absence of TOP2, but not during pharmacological inhibition, an increase in R-Loops was detected. We also observed that CSB knockdown provokes the accumulation of DSBs induced by TOP2 inhibitors. Consistent with a functional interplay, interaction between CSB and TOP2 occurred after TOP2 inhibition. This was corroborated with in vitro DNA cleavage assays where CSB stimulated the activity of TOP2. Altogether, our results show that TOP2 is stimulated by the CSB protein and prevents the accumulation of R-loops/DSBs linked to genomic instability.
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Affiliation(s)
- Franciele Faccio Busatto
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, Brazil.,Post-Graduation Program in Molecular and Cell Biology (PPGBCM), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.,Oncology Division, CHU de Québec-Université Laval, Quebec City, QC, Canada.,Laval University Cancer Research Center, Quebec City, QC, Canada
| | - Sofiane Y Mersaoui
- Oncology Division, CHU de Québec-Université Laval, Quebec City, QC, Canada.,Laval University Cancer Research Center, Quebec City, QC, Canada
| | - Yilun Sun
- Developmental Therapeutics Branch, Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Yves Pommier
- Developmental Therapeutics Branch, Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - Jean-Yves Masson
- Oncology Division, CHU de Québec-Université Laval, Quebec City, QC, Canada.,Laval University Cancer Research Center, Quebec City, QC, Canada
| | - Jenifer Saffi
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre (UFCSPA), Porto Alegre, Brazil.,Post-Graduation Program in Molecular and Cell Biology (PPGBCM), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
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45
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Castillo-Guzman D, Chédin F. Defining R-loop classes and their contributions to genome instability. DNA Repair (Amst) 2021; 106:103182. [PMID: 34303066 PMCID: PMC8691176 DOI: 10.1016/j.dnarep.2021.103182] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 01/20/2023]
Abstract
R-loops are non-B DNA structures that form during transcription when the nascent RNA anneals to the template DNA strand forming a RNA:DNA hybrid. Understanding the genomic distribution and function of R-loops is an important goal, since R-loops have been implicated in a number of adaptive and maladaptive processes under physiological and pathological conditions. Based on R-loop mapping datasets, we propose the existence of two main classes of R-loops, each associated with unique characteristics. Promoter-paused R-loops (Class I) are short R-loops that form at high frequency during promoter-proximal pausing by RNA polymerase II. Elongation-associated R-loops (Class II) are long structures that occur throughout gene bodies at modest frequencies. We further discuss the relationships between each R-loop class with instances of genome instability and suggest that increased class I R-loops, resulting from enhanced promoter-proximal pausing, represent the main culprits for R-loop mediated genome instability under pathological conditions.
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Affiliation(s)
- Daisy Castillo-Guzman
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, Davis, CA, 95616, United States
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology and Genome Center, University of California, Davis, Davis, CA, 95616, United States.
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46
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Racca C, Britton S, Hédouin S, Francastel C, Calsou P, Larminat F. BRCA1 prevents R-loop-associated centromeric instability. Cell Death Dis 2021; 12:896. [PMID: 34599155 PMCID: PMC8486751 DOI: 10.1038/s41419-021-04189-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 09/01/2021] [Accepted: 09/15/2021] [Indexed: 02/05/2023]
Abstract
Centromeres are defined by chromatin containing the histone H3 variant CENP-A assembled onto repetitive α-satellite sequences, which are actively transcribed throughout the cell cycle. Centromeres play an essential role in chromosome inheritance and genome stability through coordinating kinetochores assembly during mitosis. Structural and functional alterations of the centromeres cause aneuploidy and chromosome aberrations which can induce cell death. In human cells, the tumor suppressor BRCA1 associates with centromeric chromatin in the absence of exogenous damage. While we previously reported that BRCA1 contributes to proper centromere homeostasis, the mechanism underlying its centromeric function and recruitment was not fully understood. Here, we show that BRCA1 association with centromeric chromatin depends on the presence of R-loops, which are non-canonical three-stranded structures harboring a DNA:RNA hybrid and are frequently formed during transcription. Subsequently, BRCA1 counteracts the accumulation of R-loops at centromeric α-satellite repeats. Strikingly, BRCA1-deficient cells show impaired localization of CENP-A, higher transcription of centromeric RNA, increased breakage at centromeres and formation of acentric micronuclei, all these features being R-loop-dependent. Finally, BRCA1 depletion reveals a Rad52-dependent hyper-recombination process between centromeric satellite repeats, associated with centromere instability and missegregation. Altogether, our findings provide molecular insights into the key function of BRCA1 in maintaining centromere stability and identity.
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Affiliation(s)
- Carine Racca
- 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
| | - Sabrine Hédouin
- Université de Paris, Epigénétique et Destin Cellulaire, CNRS, Paris, F-75013, France.,Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Claire Francastel
- Université de Paris, Epigénétique et Destin Cellulaire, CNRS, Paris, F-75013, 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
| | - Florence Larminat
- 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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47
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Fleming AM, Burrows CJ. Oxidative stress-mediated epigenetic regulation by G-quadruplexes. NAR Cancer 2021; 3:zcab038. [PMID: 34541539 PMCID: PMC8445369 DOI: 10.1093/narcan/zcab038] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/20/2021] [Accepted: 09/06/2021] [Indexed: 02/06/2023] Open
Abstract
Many cancer-associated genes are regulated by guanine (G)-rich sequences that are capable of refolding from the canonical duplex structure to an intrastrand G-quadruplex. These same sequences are sensitive to oxidative damage that is repaired by the base excision repair glycosylases OGG1 and NEIL1–3. We describe studies indicating that oxidation of a guanosine base in a gene promoter G-quadruplex can lead to up- and downregulation of gene expression that is location dependent and involves the base excision repair pathway in which the first intermediate, an apurinic (AP) site, plays a key role mediated by AP endonuclease 1 (APE1/REF1). The nuclease activity of APE1 is paused at a G-quadruplex, while the REF1 capacity of this protein engages activating transcription factors such as HIF-1α, AP-1 and p53. The mechanism has been probed by in vitro biophysical studies, whole-genome approaches and reporter plasmids in cellulo. Replacement of promoter elements by a G-quadruplex sequence usually led to upregulation, but depending on the strand and precise location, examples of downregulation were also found. The impact of oxidative stress-mediated lesions in the G-rich sequence enhanced the effect, whether it was positive or negative.
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Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850, USA
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, UT 84112-0850, USA
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48
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Kumar C, Batra S, Griffith JD, Remus D. The interplay of RNA:DNA hybrid structure and G-quadruplexes determines the outcome of R-loop-replisome collisions. eLife 2021; 10:72286. [PMID: 34494544 PMCID: PMC8479836 DOI: 10.7554/elife.72286] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 09/07/2021] [Indexed: 12/11/2022] Open
Abstract
R-loops are a major source of genome instability associated with transcription-induced replication stress. However, how R-loops inherently impact replication fork progression is not understood. Here, we characterize R-loop-replisome collisions using a fully reconstituted eukaryotic DNA replication system. We find that RNA:DNA hybrids and G-quadruplexes at both co-directional and head-on R-loops can impact fork progression by inducing fork stalling, uncoupling of leading strand synthesis from replisome progression, and nascent strand gaps. RNase H1 and Pif1 suppress replication defects by resolving RNA:DNA hybrids and G-quadruplexes, respectively. We also identify an intrinsic capacity of replisomes to maintain fork progression at certain R-loops by unwinding RNA:DNA hybrids, repriming leading strand synthesis downstream of G-quadruplexes, or utilizing R-loop transcripts to prime leading strand restart during co-directional R-loop-replisome collisions. Collectively, the data demonstrates that the outcome of R-loop-replisome collisions is modulated by R-loop structure, providing a mechanistic basis for the distinction of deleterious from non-deleterious R-loops.
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Affiliation(s)
- Charanya Kumar
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Sahil Batra
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center and Departments of Microbiology and Immunology, and Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, United States
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49
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Robinson J, Raguseo F, Nuccio SP, Liano D, Di Antonio M. DNA G-quadruplex structures: more than simple roadblocks to transcription? Nucleic Acids Res 2021; 49:8419-8431. [PMID: 34255847 PMCID: PMC8421137 DOI: 10.1093/nar/gkab609] [Citation(s) in RCA: 113] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 12/12/2022] Open
Abstract
It has been >20 years since the formation of G-quadruplex (G4) secondary structures in gene promoters was first linked to the regulation of gene expression. Since then, the development of small molecules to selectively target G4s and their cellular application have contributed to an improved understanding of how G4s regulate transcription. One model that arose from this work placed these non-canonical DNA structures as repressors of transcription by preventing polymerase processivity. Although a considerable number of studies have recently provided sufficient evidence to reconsider this simplistic model, there is still a misrepresentation of G4s as transcriptional roadblocks. In this review, we will challenge this model depicting G4s as simple 'off switches' for gene expression by articulating how their formation has the potential to alter gene expression at many different levels, acting as a key regulatory element perturbing the nature of epigenetic marks and chromatin architecture.
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Affiliation(s)
- Jenna Robinson
- Imperial College London, Chemistry Department, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
| | - Federica Raguseo
- Imperial College London, Chemistry Department, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
| | - Sabrina Pia Nuccio
- Imperial College London, Chemistry Department, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
| | - Denise Liano
- Imperial College London, Chemistry Department, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
| | - Marco Di Antonio
- Imperial College London, Chemistry Department, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, 82 Wood Lane, London W12 0BZ, UK
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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50
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Wu T, Nance J, Chu F, Fazzio TG. Characterization of R-Loop-Interacting Proteins in Embryonic Stem Cells Reveals Roles in rRNA Processing and Gene Expression. Mol Cell Proteomics 2021; 20:100142. [PMID: 34478875 PMCID: PMC8461376 DOI: 10.1016/j.mcpro.2021.100142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 08/21/2021] [Accepted: 08/25/2021] [Indexed: 12/14/2022] Open
Abstract
Chromatin-associated RNAs have diverse roles in the nucleus. However, their mechanisms of action are poorly understood, in part because of the inability to identify proteins that specifically associate with chromatin-bound RNAs. Here, we address this problem for a subset of chromatin-associated RNAs that form R-loops-RNA-DNA hybrid structures that include a displaced strand of ssDNA. R-loops generally form cotranscriptionally and have important roles in regulation of gene expression, immunoglobulin class switching, and other processes. However, unresolved R-loops can lead to DNA damage and chromosome instability. To identify factors that may bind and regulate R-loop accumulation or mediate R-loop-dependent functions, we used a comparative immunoprecipitation/MS approach, with and without RNA-protein crosslinking, to identify a stringent set of R-loop-binding proteins in mouse embryonic stem cells. We identified 364 R-loop-interacting proteins, which were highly enriched for proteins with predicted RNA-binding functions. We characterized several R-loop-interacting proteins of the DEAD-box family of RNA helicases and found that these proteins localize to the nucleolus and, to a lesser degree, the nucleus. Consistent with their localization patterns, we found that these helicases are required for rRNA processing and regulation of gene expression. Surprisingly, depletion of these helicases resulted in misregulation of highly overlapping sets of protein-coding genes, including many genes that function in differentiation and development. We conclude that R-loop-interacting DEAD-box helicases have nonredundant roles that are critical for maintaining the normal embryonic stem cell transcriptome.
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Affiliation(s)
- Tong Wu
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Jennifer Nance
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
| | - Feixia Chu
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
| | - Thomas G Fazzio
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
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