1
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Wanat JJ, McCann JJ, Tingey M, Atkins J, Merlino CO, Lee-Soety JY. Yeast Npl3 regulates replicative senescence outside of TERRA R-loop resolution and co-transcriptional processing. NUCLEOSIDES, NUCLEOTIDES & NUCLEIC ACIDS 2024:1-21. [PMID: 38976968 DOI: 10.1080/15257770.2024.2374023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 06/20/2024] [Indexed: 07/10/2024]
Abstract
Eukaryotic cells without telomerase experience progressively shorter telomeres with each round of cell division until cell cycle arrest is initiated, leading to replicative senescence. When yeast TLC1, which encodes the RNA template of telomerase, is deleted, senescence is accompanied by increased expression of TERRA (non-coding telomere repeat-containing RNA). Deletion of Npl3, an RNA-processing protein with telomere maintenance functions, accelerates senescence in tlc1Δ cells and significantly increases TERRA levels. Using genetic approaches, we set out to determine how Npl3 is involved in regulating TERRA expression and maintaining telomere homeostasis. Even though Npl3 regulates hyperrecombination, we found that Npl3 does not help resolve RNA:DNA hybrids formed during TERRA synthesis in the same way as RNase H1 and H2. Furthermore, Rad52 is still required for cells to escape senescence by telomere recombination in the absence of Npl3. Npl3 also works separately from the THO/TREX pathway for processing nascent RNA for nuclear export. However, deleting Dot1, a histone methyltransferase involved in tethering telomeres to the nuclear periphery, rescued the accelerated senescence phenotype of npl3Δ cells. Thus, our study suggests that Npl3 plays an additional role in regulating cellular senescence outside of RNA:DNA hybrid resolution and co-transcriptional processing.
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Affiliation(s)
- Jennifer J Wanat
- Department of Biology, Washington College, Chestertown, Maryland, USA
| | - Jennifer J McCann
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Mark Tingey
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Jessica Atkins
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Corinne O Merlino
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Julia Y Lee-Soety
- Department of Biology, Saint Joseph's University, Philadelphia, Pennsylvania, USA
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2
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Lafuente-Barquero J, Svejstrup JQ, Luna R, Aguilera A. Expression of human RECQL5 in Saccharomyces cerevisiae causes transcription defects and transcription-associated genome instability. Mol Genet Genomics 2024; 299:59. [PMID: 38796829 PMCID: PMC11128410 DOI: 10.1007/s00438-024-02152-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 05/13/2024] [Indexed: 05/29/2024]
Abstract
RECQL5 is a member of the conserved RecQ family of DNA helicases involved in the maintenance of genome stability that is specifically found in higher eukaryotes and associates with the elongating RNA polymerase II. To expand our understanding of its function we expressed human RECQL5 in the yeast Saccharomyces cerevisiae, which does not have a RECQL5 ortholog. We found that RECQL5 expression leads to cell growth inhibition, increased genotoxic sensitivity and transcription-associated hyperrecombination. Chromatin immunoprecipitation and transcriptomic analysis of yeast cells expressing human RECQL5 shows that this is recruited to transcribed genes and although it causes only a weak impact on gene expression, in particular at G + C-rich genes, it leads to a transcription termination defect detected as readthrough transcription. The data indicate that the interaction between RNAPII and RECQL5 is conserved from yeast to humans. Unexpectedly, however, the RECQL5-ID mutant, previously shown to have reduced the association with RNAPII in vitro, associates with the transcribing polymerase in cells. As a result, expression of RECQL5-ID leads to similar although weaker phenotypes than wild-type RECQL5 that could be transcription-mediated. Altogether, the data suggests that RECQL5 has the intrinsic ability to function in transcription-dependent and independent genome dynamics in S. cerevisiae.
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Affiliation(s)
- Juan Lafuente-Barquero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012, Seville, Spain
| | - Jesper Q Svejstrup
- University of Copenhagen, Copenhagen, Denmark
- Francis Crick Institute, London, UK
| | - Rosa Luna
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain.
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012, Seville, Spain.
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012, Seville, Spain
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3
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Piguet B, Houseley J. Transcription as source of genetic heterogeneity in budding yeast. Yeast 2024; 41:171-185. [PMID: 38196235 DOI: 10.1002/yea.3926] [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: 10/07/2023] [Revised: 12/10/2023] [Accepted: 12/20/2023] [Indexed: 01/11/2024] Open
Abstract
Transcription presents challenges to genome stability both directly, by altering genome topology and exposing single-stranded DNA to chemical insults and nucleases, and indirectly by introducing obstacles to the DNA replication machinery. Such obstacles include the RNA polymerase holoenzyme itself, DNA-bound regulatory factors, G-quadruplexes and RNA-DNA hybrid structures known as R-loops. Here, we review the detrimental impacts of transcription on genome stability in budding yeast, as well as the mitigating effects of transcription-coupled nucleotide excision repair and of systems that maintain DNA replication fork processivity and integrity. Interactions between DNA replication and transcription have particular potential to induce mutation and structural variation, but we conclude that such interactions must have only minor effects on DNA replication by the replisome with little if any direct mutagenic outcome. However, transcription can significantly impair the fidelity of replication fork rescue mechanisms, particularly Break Induced Replication, which is used to restart collapsed replication forks when other means fail. This leads to de novo mutations, structural variation and extrachromosomal circular DNA formation that contribute to genetic heterogeneity, but only under particular conditions and in particular genetic contexts, ensuring that the bulk of the genome remains extremely stable despite the seemingly frequent interactions between transcription and DNA replication.
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4
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Liu H, Deng S, Yao X, Liu Y, Qian L, Wang Y, Zhang T, Shan G, Chen L, Zhou Y. Ascites exosomal lncRNA PLADE enhances platinum sensitivity by inducing R-loops in ovarian cancer. Oncogene 2024; 43:714-728. [PMID: 38225339 DOI: 10.1038/s41388-024-02940-6] [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: 07/12/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 01/17/2024]
Abstract
Cisplatin resistance is a major cause of therapeutic failure in patients with high-grade serous ovarian cancer (HGSOC). Long noncoding RNAs (lncRNAs) have emerged as key regulators of human cancers; however, their modes of action in HGSOC remain largely unknown. Here, we provide evidence to demonstrate that lncRNA Platinum sensitivity-related LncRNA from Ascites-Derived Exosomes (PLADE) transmitted by ascites exosomes enhance platinum sensitivity in HGSOC. PLADE exhibited significantly decreased expression in ascites exosomes and tumor tissues, as well as in the corresponding metastatic tumors from patients with HGSOC cisplatin-resistance. Moreover, HGSOC patients with higher PLADE expression levels exhibited longer progression-free survival. Gain- and loss-of-function studies have revealed that PLADE promotes cisplatin sensitivity by suppressing cell proliferation, migration and invasion, and enhancing apoptosis in vitro and in vivo. Furthermore, the functions of PLADE in increasing cisplatin sensitivity were proven to be transferred by exosomes to the cultured recipient cells and to the adjacent tumor tissues in mouse models. Mechanistically, PLADE binds to and downregulates heterogeneous nuclear ribonucleoprotein D (HNRNPD) by VHL-mediated ubiquitination, thus inducing an increased amount of RNA: DNA hybrids (R-loop) and DNA damage, consequently promoting cisplatin sensitivity in HGSOC. Collectively, these results shed light on the understanding of the vital roles of long noncoding RNAs in cancers.
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Affiliation(s)
- Hanyuan Liu
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Sisi Deng
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Xuelin Yao
- Department of Endocrinology, The First Affiliated Hospital of Anhui Medical University, Hefei, 230032, China
| | - Yi Liu
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Lili Qian
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Yingying Wang
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Tianjiao Zhang
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China
| | - Ge Shan
- Department of Clinical Laboratory, The First Affiliated Hospital of USTC, School of Basic Medical Sciences, Division of Life Science and Medicine, University of Science and Technology of China, Hefei, 230027, China.
| | - Liang Chen
- Department of Cardiology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China.
| | - Ying Zhou
- Department of Obstetrics and Gynecology, Core Facility Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, 230001, China.
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5
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Moursy A, Cléry A, Gerhardy S, Betz KM, Rao S, Mazur J, Campagne S, Beusch I, Duszczyk MM, Robinson MD, Panse VG, Allain FHT. RNA recognition by Npl3p reveals U2 snRNA-binding compatible with a chaperone role during splicing. Nat Commun 2023; 14:7166. [PMID: 37935663 PMCID: PMC10630445 DOI: 10.1038/s41467-023-42962-4] [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: 08/31/2022] [Accepted: 10/27/2023] [Indexed: 11/09/2023] Open
Abstract
The conserved SR-like protein Npl3 promotes splicing of diverse pre-mRNAs. However, the RNA sequence(s) recognized by the RNA Recognition Motifs (RRM1 & RRM2) of Npl3 during the splicing reaction remain elusive. Here, we developed a split-iCRAC approach in yeast to uncover the consensus sequence bound to each RRM. High-resolution NMR structures show that RRM2 recognizes a 5´-GNGG-3´ motif leading to an unusual mille-feuille topology. These structures also reveal how RRM1 preferentially interacts with a CC-dinucleotide upstream of this motif, and how the inter-RRM linker and the region C-terminal to RRM2 contribute to cooperative RNA-binding. Structure-guided functional studies show that Npl3 genetically interacts with U2 snRNP specific factors and we provide evidence that Npl3 melts U2 snRNA stem-loop I, a prerequisite for U2/U6 duplex formation within the catalytic center of the Bact spliceosomal complex. Thus, our findings suggest an unanticipated RNA chaperoning role for Npl3 during spliceosome active site formation.
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Affiliation(s)
- Ahmed Moursy
- Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Antoine Cléry
- Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland.
| | - Stefan Gerhardy
- Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
- Sardona Therapeutics, San Francisco, CA, USA
| | - Katharina M Betz
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Sanjana Rao
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Jarosław Mazur
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Sébastien Campagne
- Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland
- ARNA laboratory, INSERM U1212, University of Bordeaux, Bordeaux, France
| | - Irene Beusch
- Department of Biology, Institute of Biochemistry, ETH Zurich, Switzerland
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | | | - Mark D Robinson
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Vikram Govind Panse
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
- Faculty of Science, University of Zurich, Zurich, Switzerland.
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6
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Zhou H, Yan Y, Gao J, Ma M, Liu Y, Shi X, Zhang Q, Xu X. Heterogeneous Nuclear Protein U Degraded the m 6A Methylated TRAF3 Transcript by YTHDF2 To Promote Porcine Epidemic Diarrhea Virus Replication. J Virol 2023; 97:e0175122. [PMID: 36752613 PMCID: PMC9973030 DOI: 10.1128/jvi.01751-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 01/06/2023] [Indexed: 02/09/2023] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) belongs to the genus Alphacoronavirus of the Coronaviridae family and can cause fatal watery diarrhea in piglets, causing significant economic losses. Heterogeneous nuclear protein U (HNRNPU) is a novel RNA sensor involved in sensing viral RNA in the nucleus and mediating antiviral immunity. However, it remains elusive whether and how cytoplasmic PEDV can be sensed by the RNA sensor HNRNPU. In this study we determined that HNRNPU was the binding partner of Nsp13 by immunoprecipitation-liquid chromatography-tandem mass spectrometry (IP/LC-MS/MS) analysis. The interaction between Nsp13 and HNRNPU was demonstrated by using coimmunoprecipitation and confocal immunofluorescence. Next, we identified that HNRNPU expression is significantly increased during PEDV infection, whereas the transcription factor hepatocyte nuclear factor 1α (HNF1A) could negatively regulate HNRNPU expression. HNRNPU was retained in the cytoplasm by interaction with PEDV Nsp13. We found that HNRNPU overexpression effectively facilitated PEDV replication, while knockdown of HNRNPU impaired viral replication, suggesting a promoting function of HNRNPU to PEDV infection. Additionally, HNRNPU was found to promote PEDV replication by affecting TRAF3 degradation at the transcriptional level to inhibit PEDV-induced beta interferon (IFN-β) production. Mechanistically, HNRNPU downregulates TRAF3 mRNA levels via the METTL3-METTL14/YTHDF2 axis and regulates immune responses through YTHDF2-dependent mRNA decay. Together, our findings reveal that HNRNPU serves as a negative regulator of innate immunity by degrading TRAF3 mRNA in a YTHDF2-dependent manner and consequently facilitating PEDV propagation. Our findings provide new insights into the immune escape of PEDV. IMPORTANCE PEDV, a highly infectious enteric coronavirus, has spread rapidly worldwide and caused severe economic losses. During virus infection, the host regulates innate immunity to inhibit virus infection. However, PEDV has evolved a variety of different strategies to suppress host IFN-mediated antiviral responses. Here, we identified that HNRNPU interacted with viral protein Nsp13. HNRNPU protein expression was upregulated, and the transcription factor HNF1A could negatively regulate HNRNPU expression during PEDV infection. HNRNPU also downregulated TRAF3 mRNA through the METTL3-METTL14/YTHDF2 axis to inhibit the production of IFN-β and downstream antiviral genes in PEDV-infected cells, thereby promoting viral replication. Our findings reveal a new mechanism with which PEDV suppresses the host antiviral response.
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Affiliation(s)
- Hongchao Zhou
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Yuchao Yan
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Jie Gao
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Mingrui Ma
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Yi Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Xiaojie Shi
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Qi Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
| | - Xingang Xu
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
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7
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Gospodinov A, Dzhokova S, Petrova M, Ugrinova I. Chromatin regulators in DNA replication and genome stability maintenance during S-phase. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 135:243-280. [PMID: 37061334 DOI: 10.1016/bs.apcsb.2023.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
The duplication of genetic information is central to life. The replication of genetic information is strictly controlled to ensure that each piece of genomic DNA is copied only once during a cell cycle. Factors that slow or stop replication forks cause replication stress. Replication stress is a major source of genome instability in cancer cells. Multiple control mechanisms facilitate the unimpeded fork progression, prevent fork collapse and coordinate fork repair. Chromatin alterations, caused by histone post-translational modifications and chromatin remodeling, have critical roles in normal replication and in avoiding replication stress and its consequences. This text reviews the chromatin regulators that ensure DNA replication and the proper response to replication stress. We also briefly touch on exploiting replication stress in therapeutic strategies. As chromatin regulators are frequently mutated in cancer, manipulating their activity could provide many possibilities for personalized treatment.
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Affiliation(s)
- Anastas Gospodinov
- Roumen Tsanev Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
| | - Stefka Dzhokova
- Roumen Tsanev Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Maria Petrova
- Roumen Tsanev Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Iva Ugrinova
- Roumen Tsanev Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria
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8
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Hu X, Wu X, Ding Z, Chen Z, Wu H. Characterization and functional analysis of chicken dsRNA binding protein hnRNPU. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 138:104521. [PMID: 36044969 DOI: 10.1016/j.dci.2022.104521] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
In mammals, heterogeneous ribonucleoprotein U (hnRNPU), also named as nuclear matrix protein-nuclear scaffold attachment factor (SAFA), was originally identified as a DNA/RNA interactor protein. It has been reported that human hnRNPU facilitates IFN-β generation after vesicular stomatitis virus (VSV) infection. Nevertheless, the role of chicken hnRNPU (chhnRNPU) in IFN-β regulation as well as in infectious bursal diseases virus (IBDV) replication is still unclear. Here, we found that chhnRNPU inhibits IFN-β production via interacting with MDA5 and MAVS, and facilitates IBDV replication via associating with genomic dsRNA of IBDV. Firstly, chicken hnRNPU (chhnRNPU) was widely expressed in different tissues of chickens and was distributed in the nucleus of DF-1 cells. Overexpression of chhnRNPU significantly suppresses IFN-β promoter activities induced by MDA5 and MAVS. Additionally, immunoprecipitated by dsRNA antibodies, which followed LC-MS analysis demonstrate that chhnRNPU is a partner of viral genomic dsRNA. chhnRNPU is translocated from nucleus to cytosol to co-localize with replication complex of IBDV after IBDV infection. Over-expression of chhnRNPU significantly promotes IBDV replication, which was determined by western blotting, qRT-PCR and TCID50 assay. Furthermore, knock down chhnRNPU by siRNA remarkably facilitates IFN-β production, and inhibits IBDV proliferation. These data collectively reveal that chhnRNPU positively regulates IBDV replication via negatively regulating IFN-β response.
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Affiliation(s)
- Xifeng Hu
- Department of Veterinary Preventive Medicine, College of Animal Science and Technology, Jiangxi Agricultural University, Zhimin Street, Qingshan Lake, Nanchang, 330045, PR China; Jiangxi Provincial Key Laboratory for Animal Science and Technology, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Xiangdong Wu
- Department of Veterinary Preventive Medicine, College of Animal Science and Technology, Jiangxi Agricultural University, Zhimin Street, Qingshan Lake, Nanchang, 330045, PR China; Jiangxi Provincial Key Laboratory for Animal Science and Technology, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Zhen Ding
- Department of Veterinary Preventive Medicine, College of Animal Science and Technology, Jiangxi Agricultural University, Zhimin Street, Qingshan Lake, Nanchang, 330045, PR China; Jiangxi Provincial Key Laboratory for Animal Science and Technology, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Zheng Chen
- Department of Veterinary Preventive Medicine, College of Animal Science and Technology, Jiangxi Agricultural University, Zhimin Street, Qingshan Lake, Nanchang, 330045, PR China; Jiangxi Provincial Key Laboratory for Animal Science and Technology, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Huansheng Wu
- Department of Veterinary Preventive Medicine, College of Animal Science and Technology, Jiangxi Agricultural University, Zhimin Street, Qingshan Lake, Nanchang, 330045, PR China; Jiangxi Provincial Key Laboratory for Animal Science and Technology, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, 330045, PR China.
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9
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RNase HI Depletion Strongly Potentiates Cell Killing by Rifampicin in Mycobacteria. Antimicrob Agents Chemother 2022; 66:e0209121. [PMID: 36154174 DOI: 10.1128/aac.02091-21] [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: 11/20/2022] Open
Abstract
Multidrug-resistant (MDR) tuberculosis (TB) is defined by the resistance of Mycobacterium tuberculosis, the causative organism, to the first-line antibiotics rifampicin and isoniazid. Mitigating or reversing resistance to these drugs offers a means of preserving and extending their use in TB treatment. R-loops are RNA/DNA hybrids that are formed in the genome during transcription, and they can be lethal to the cell if not resolved. RNase HI is an enzyme that removes R-loops, and this activity is essential in M. tuberculosis: knockouts of rnhC, the gene encoding RNase HI, are nonviable. This essentiality makes it a candidate target for the development of new antibiotics. In the model organism Mycolicibacterium smegmatis, RNase HI activity is provided by two enzymes, RnhA and RnhC. We show that the partial depletion of RNase HI activity in M. smegmatis, by knocking out either of the genes encoding RnhA or RnhC, led to the accumulation of R-loops. The sensitivity of the knockout strains to the antibiotics moxifloxacin, streptomycin, and rifampicin was increased, the latter by a striking near 100-fold. We also show that R-loop accumulation accompanies partial transcriptional inhibition, suggesting a mechanistic basis for the synergy between RNase HI depletion and rifampicin. A model of how transcriptional inhibition can potentiate R-loop accumulation is presented. Finally, we identified four small molecules that inhibit recombinant RnhC activity and that also potentiated rifampicin activity in whole-cell assays against M. tuberculosis, supporting an on-target mode of action and providing the first step in developing a new class of antimycobacterial drug.
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10
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Pérez-Martínez L, Wagner T, Luke B. Telomere Interacting Proteins and TERRA Regulation. Front Genet 2022; 13:872636. [PMID: 35464834 PMCID: PMC9024143 DOI: 10.3389/fgene.2022.872636] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/17/2022] [Indexed: 01/10/2023] Open
Abstract
Telomere shortening rates inversely correlate with life expectancy and hence it is critical to understand how telomere shortening is regulated. Recently, the telomeric non-coding RNA, TERRA has been implicated in the regulation of replicative senescence. To better understand how TERRA is regulated we employed a proteomics approach to look for potential RNA regulators that associate with telomeric sequences. Based on the results, we have identified proteins that may regulate TERRA in both a positive and negative manner, depending on the state of the telomere. In this mini-review, we discuss and speculate about these data to expand our understanding of TERRA and telomere interactors with respect to telomere shortening dynamics.
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Affiliation(s)
- Lara Pérez-Martínez
- Institute of Molecular Biology (IMB), Mainz, Germany
- IMDEA Food Institute, Madrid, Spain
| | - Tina Wagner
- Institute of Molecular Biology (IMB), Mainz, Germany
- Institute of Developmental Biology and Neurobiology (IDN), Johannes Gutenberg Universität, Mainz, Germany
| | - Brian Luke
- Institute of Molecular Biology (IMB), Mainz, Germany
- Institute of Developmental Biology and Neurobiology (IDN), Johannes Gutenberg Universität, Mainz, Germany
- *Correspondence: Brian Luke,
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11
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Beghè C, Gromak N. R-Loop Immunoprecipitation: A Method to Detect R-Loop Interacting Factors. Methods Mol Biol 2022; 2528:215-237. [PMID: 35704194 DOI: 10.1007/978-1-0716-2477-7_14] [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: 06/15/2023]
Abstract
R-loops are non-B-DNA structures consisting of an RNA/DNA hybrid and a displaced single-stranded DNA. They arise during transcription and play important biological roles. However, perturbation of R-loop levels represents a source of DNA damage and genome instability resulting in human diseases, including cancer and neurodegeneration. In this chapter, we describe a protocol which allows detection of R-loop interactors using affinity purification with S9.6 antibody, specific for RNA/DNA hybrids, followed by Western blotting or mass spectrometry. Multiple specificity controls including addition of synthetic competitors and RNase H treatment are described to verify the specificity of identified R-loop-binding factors. The identification of new R-loop interacting factors and the characterization of their involvement in R-loop biology provides a powerful resource to study the role of these important structures in health and disease.
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Affiliation(s)
- Chiara Beghè
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Natalia Gromak
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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12
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Kim A, Wang GG. R-loop and its functions at the regulatory interfaces between transcription and (epi)genome. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2021; 1864:194750. [PMID: 34461314 PMCID: PMC8627470 DOI: 10.1016/j.bbagrm.2021.194750] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/10/2021] [Accepted: 08/19/2021] [Indexed: 01/08/2023]
Abstract
R-loop represents a prevalent and specialized chromatin structure critically involved in a wide range of biological processes. In particular, co-transcriptional R-loops, produced often due to RNA polymerase pausing or RNA biogenesis malfunction, can initiate molecular events to context-dependently regulate local gene transcription and crosstalk with chromatin modifications. Cellular "readers" of R-loops are identified, exerting crucial impacts on R-loop homeostasis and gene regulation. Mounting evidence also supports R-loop deregulation as a frequent, sometimes initiating, event during the development of human pathologies, notably cancer and neurological disorder. The purpose of this review is to cover recent advances in understanding the fundamentals of R-loop biology, which have started to unveil complex interplays of R-loops with factors involved in various biological processes such as transcription, RNA processing and epitranscriptomic modification (such as N6-methyladenosine), DNA damage sensing and repair, and epigenetic regulation.
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Affiliation(s)
- Arum Kim
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Gang Greg Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA.
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13
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Gao J, Zhang P, Li X, Wu W, Wei H, Zhang W. Toward an understanding of the detection and function of R-loops in plants. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6110-6122. [PMID: 34115858 DOI: 10.1093/jxb/erab280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 06/10/2021] [Indexed: 06/12/2023]
Abstract
Although lagging behind studies in humans and other mammals, studies of R-loops in plants have recently entered an exciting stage in which the roles of R-loops in gene expression, genome stability, epigenomic signatures, and plant development and stress responses are being elucidated. Here, we review the strengths and weaknesses of existing methodologies, which were largely developed for R-loop studies in mammals, and then discuss the potential challenges of applying these methodologies to R-loop studies in plants. We then focus on recent advances in the functional characterization of R-loops in Arabidopsis thaliana and rice. Recent studies in plants indicate that there are coordinated relationships between R-loops and gene expression, and between R-loops and epigenomic signatures that depend, in part, on the types of R-loops involved. Finally, we discuss the emerging roles of R-loops in plants and directions for future research.
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Affiliation(s)
- Jingjing Gao
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, JCIC-MCP, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Pengyue Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, JCIC-MCP, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Xinxu Li
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, JCIC-MCP, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
| | - Wenqi Wu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
| | - Hairong Wei
- College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI 49931, USA
| | - Wenli Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, JCIC-MCP, CIC-MCP, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu 210095, China
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14
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Transcription and chromatin-based surveillance mechanism controls suppression of cryptic antisense transcription. Cell Rep 2021; 36:109671. [PMID: 34496258 PMCID: PMC8441049 DOI: 10.1016/j.celrep.2021.109671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/26/2020] [Accepted: 08/13/2021] [Indexed: 12/25/2022] Open
Abstract
Phosphorylation of the RNA polymerase II C-terminal domain Y1S2P3T4S5P6S7 consensus sequence coordinates key events during transcription, and its deregulation leads to defects in transcription and RNA processing. Here, we report that the histone deacetylase activity of the fission yeast Hos2/Set3 complex plays an important role in suppressing cryptic initiation of antisense transcription when RNA polymerase II phosphorylation is dysregulated due to the loss of Ssu72 phosphatase. Interestingly, although single Hos2 and Set3 mutants have little effect, loss of Hos2 or Set3 combined with ssu72Δ results in a synergistic increase in antisense transcription globally and correlates with elevated sensitivity to genotoxic agents. We demonstrate a key role for the Ssu72/Hos2/Set3 mechanism in the suppression of cryptic antisense transcription at the 3' end of convergent genes that are most susceptible to these defects, ensuring the fidelity of gene expression within dense genomes of simple eukaryotes.
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15
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Sandhu R, Sinha A, Montpetit B. The SR-protein Npl3 is an essential component of the meiotic splicing regulatory network in Saccharomyces cerevisiae. Nucleic Acids Res 2021; 49:2552-2568. [PMID: 33577675 PMCID: PMC7969001 DOI: 10.1093/nar/gkab071] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 01/30/2023] Open
Abstract
The meiotic gene expression program in Saccharomyces cerevisiae involves regulated splicing of meiosis-specific genes via multiple splicing activators (e.g. Mer1, Nam8, Tgs1). Here, we show that the SR protein Npl3 is required for meiotic splicing regulation and is essential for proper execution of the meiotic cell cycle. The loss of Npl3, though not required for viability in mitosis, caused intron retention in meiosis-specific transcripts, inefficient meiotic double strand break processing and an arrest of the meiotic cell cycle. The targets of Npl3 overlapped in some cases with other splicing regulators, while also having unique target transcripts that were not shared. In the absence of Npl3, splicing defects for three transcripts (MER2, HOP2 and SAE3) were rescued by conversion of non-consensus splice sites to the consensus sequence. Methylation of Npl3 was further found to be required for splicing Mer1-dependent transcripts, indicating transcript-specific mechanisms by which Npl3 supports splicing. Together these data identify an essential function for the budding yeast SR protein Npl3 in meiosis as part of the meiotic splicing regulatory network.
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Affiliation(s)
- Rima Sandhu
- Department of Viticulture and Enology, University of California Davis, Davis, CA, USA
| | - Aniketa Sinha
- Department of Viticulture and Enology, University of California Davis, Davis, CA, USA
| | - Ben Montpetit
- Department of Viticulture and Enology, University of California Davis, Davis, CA, USA
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16
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The Regulatory Properties of the Ccr4-Not Complex. Cells 2020; 9:cells9112379. [PMID: 33138308 PMCID: PMC7692201 DOI: 10.3390/cells9112379] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/21/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022] Open
Abstract
The mammalian Ccr4–Not complex, carbon catabolite repression 4 (Ccr4)-negative on TATA-less (Not), is a large, highly conserved, multifunctional assembly of proteins that acts at different cellular levels to regulate gene expression. In the nucleus, it is involved in the regulation of the cell cycle, chromatin modification, activation and inhibition of transcription initiation, control of transcription elongation, RNA export, nuclear RNA surveillance, and DNA damage repair. In the cytoplasm, the Ccr4–Not complex plays a central role in mRNA decay and affects protein quality control. Most of our original knowledge of the Ccr4–Not complex is derived, primarily, from studies in yeast. More recent studies have shown that the mammalian complex has a comparable structure and similar properties. In this review, we summarize the evidence for the multiple roles of both the yeast and mammalian Ccr4–Not complexes, highlighting their similarities.
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17
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Depletion of the MFAP1/SPP381 Splicing Factor Causes R-Loop-Independent Genome Instability. Cell Rep 2020; 28:1551-1563.e7. [PMID: 31390568 PMCID: PMC6693559 DOI: 10.1016/j.celrep.2019.07.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 03/18/2019] [Accepted: 07/01/2019] [Indexed: 01/19/2023] Open
Abstract
THO/TREX is a conserved complex with a role in messenger ribonucleoprotein biogenesis that links gene expression and genome instability. Here, we show that human THO interacts with MFAP1 (microfibrillar-associated protein 1), a spliceosome-associated factor. Interestingly, MFAP1 depletion impairs cell proliferation and genome integrity, increasing γH2AX foci and DNA breaks. This phenotype is not dependent on either transcription or RNA-DNA hybrids. Mutations in the yeast orthologous gene SPP381 cause similar transcription-independent genome instability, supporting a conserved role. MFAP1 depletion has a wide effect on splicing and gene expression in human cells, determined by transcriptome analyses. MFAP1 depletion affects a number of DNA damage response (DDR) genes, which supports an indirect role of MFAP1 on genome integrity. Our work defines a functional interaction between THO and RNA processing and argues that splicing factors may contribute to genome integrity indirectly by regulating the expression of DDR genes rather than by a direct role.
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18
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Lafuente-Barquero J, García-Rubio ML, Martin-Alonso MS, Gómez-González B, Aguilera A. Harmful DNA:RNA hybrids are formed in cis and in a Rad51-independent manner. eLife 2020; 9:56674. [PMID: 32749214 PMCID: PMC7431130 DOI: 10.7554/elife.56674] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 08/03/2020] [Indexed: 12/20/2022] Open
Abstract
DNA:RNA hybrids constitute a well-known source of recombinogenic DNA damage. The current literature is in agreement with DNA:RNA hybrids being produced co-transcriptionally by the invasion of the nascent RNA molecule produced in cis with its DNA template. However, it has also been suggested that recombinogenic DNA:RNA hybrids could be facilitated by the invasion of RNA molecules produced in trans in a Rad51-mediated reaction. Here, we tested the possibility that such DNA:RNA hybrids constitute a source of recombinogenic DNA damage taking advantage of Rad51-independent single-strand annealing (SSA) assays in the yeast Saccharomyces cerevisiae. For this, we used new constructs designed to induce expression of mRNA transcripts in trans with respect to the SSA system. We show that unscheduled and recombinogenic DNA:RNA hybrids that trigger the SSA event are formed in cis during transcription and in a Rad51-independent manner. We found no evidence that such hybrids form in trans and in a Rad51-dependent manner.
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Affiliation(s)
- Juan Lafuente-Barquero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Maria Luisa García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Marta San Martin-Alonso
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
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19
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Pérez-Martínez L, Öztürk M, Butter F, Luke B. Npl3 stabilizes R-loops at telomeres to prevent accelerated replicative senescence. EMBO Rep 2020; 21:e49087. [PMID: 32026548 PMCID: PMC7054685 DOI: 10.15252/embr.201949087] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 01/10/2020] [Accepted: 01/13/2020] [Indexed: 01/12/2023] Open
Abstract
Telomere shortening rates must be regulated to prevent premature replicative senescence. TERRA R‐loops become stabilized at critically short telomeres to promote their elongation through homology‐directed repair (HDR), thereby counteracting senescence onset. Using a non‐bias proteomic approach to detect telomere binding factors, we identified Npl3, an RNA‐binding protein previously implicated in multiple RNA biogenesis processes. Using chromatin immunoprecipitation and RNA immunoprecipitation, we demonstrate that Npl3 interacts with TERRA and telomeres. Furthermore, we show that Npl3 associates with telomeres in an R‐loop‐dependent manner, as changes in R‐loop levels, for example, at short telomeres, modulate the recruitment of Npl3 to chromosome ends. Through a series of genetic and biochemical approaches, we reveal that Npl3 binds to TERRA and stabilizes R‐loops at short telomeres, which in turn promotes HDR and prevents premature replicative senescence onset. This may have implications for diseases associated with excessive telomere shortening.
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Affiliation(s)
| | - Merve Öztürk
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - Brian Luke
- Institute of Molecular Biology (IMB), Mainz, Germany.,Institute of Developmental Biology and Neurobiology (IDN), Johannes Gutenberg Universität, Mainz, Germany
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20
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Abstract
Transcription is a source of genome instability that stimulates mutation and recombination. Part of the damage produced by transcription is mediated by R-loops, non-B DNA structures that normally form by the re-annealing of the nascent RNA with the template DNA outside the catalytic center of the RNA polymerase, displacing the non-template strand. Recent discoveries have revealed that R-loops might not be harmful by themselves. Instead, chromatin compaction triggered by these structures seems necessary, as deduced from the histone modifications frequently found associated with harmful R-loops. Remarkably, hybrids may also become harmful if stabilized by specific RNA binding proteins, one example of which is the yeast Yra1. We discuss here the possible mechanisms by which cells may stabilize R-loops and the consequences on transcription-replication conflicts and telomere homeostasis.
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Affiliation(s)
- Ana G Rondón
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, 41092, Seville, Spain.
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21
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Yuan W, Zhou J, Tong J, Zhuo W, Wang L, Li Y, Sun Q, Qian W. ALBA protein complex reads genic R-loops to maintain genome stability in Arabidopsis. SCIENCE ADVANCES 2019; 5:eaav9040. [PMID: 31106272 PMCID: PMC6520018 DOI: 10.1126/sciadv.aav9040] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 04/02/2019] [Indexed: 05/19/2023]
Abstract
The R-loop, composed of a DNA-RNA hybrid and the displaced single-stranded DNA, regulates diverse cellular processes. However, how cellular R-loops are recognized remains poorly understood. Here, we report the discovery of the evolutionally conserved ALBA proteins (AtALBA1 and AtALBA2) functioning as the genic R-loop readers in Arabidopsis. While AtALBA1 binds to the DNA-RNA hybrid, AtALBA2 associates with single-stranded DNA in the R-loops in vitro. In vivo, these two proteins interact and colocalize in the nucleus, where they preferentially bind to genic regions with active epigenetic marks in an R-loop-dependent manner. Depletion of AtALBA1 or AtALBA2 results in hypersensitivity of plants to DNA damaging agents. The formation of DNA breaks in alba mutants originates from unprotected R-loops. Our results reveal that the AtALBA1 and AtALBA2 protein complex is the genic R-loop reader crucial for genome stability in Arabidopsis.
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Affiliation(s)
- Wei Yuan
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jincong Zhou
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Jinjin Tong
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Tsinghua-Peking Joint Center for Life Sciences and Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wanqing Zhuo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Lishuan Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yan Li
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Qianwen Sun
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Corresponding author. (Q.S.); (W.Q.)
| | - Weiqiang Qian
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Corresponding author. (Q.S.); (W.Q.)
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22
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Petti E, Buemi V, Zappone A, Schillaci O, Broccia PV, Dinami R, Matteoni S, Benetti R, Schoeftner S. SFPQ and NONO suppress RNA:DNA-hybrid-related telomere instability. Nat Commun 2019; 10:1001. [PMID: 30824709 PMCID: PMC6397292 DOI: 10.1038/s41467-019-08863-1] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 01/21/2019] [Indexed: 12/15/2022] Open
Abstract
In vertebrates, the telomere repeat containing long, non-coding RNA TERRA is prone to form RNA:DNA hybrids at telomeres. This results in the formation of R-loop structures, replication stress and telomere instability, but also contributes to alternative lengthening of telomeres (ALT). Here, we identify the TERRA binding proteins NONO and SFPQ as novel regulators of RNA:DNA hybrid related telomere instability. NONO and SFPQ locate at telomeres and have a common role in suppressing RNA:DNA hybrids and replication defects at telomeres. NONO and SFPQ act as heterodimers to suppress fragility and homologous recombination at telomeres, respectively. Combining increased telomere fragility with unleashing telomere recombination upon NONO/SFPQ loss of function causes massive recombination events, involving 35% of telomeres in ALT cells. Our data identify the RNA binding proteins SFPQ and NONO as novel regulators at telomeres that collaborate to ensure telomere integrity by suppressing telomere fragility and homologous recombination triggered by RNA:DNA hybrids. LncRNA TERRA forms RNA-DNA hybrids at telomere sites leading to telomere instability. Here the authors identify the RNA interacting factors NONO and SFPQ as proteins that interact with TERRA and telomere chromatin and reveal putative roles for these factors in telomere integry maintenance by interfering with RNA:DNA hybrid formation.
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Affiliation(s)
- Eleonora Petti
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy.,Department of Life Sciences, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.,Oncogenomic and Epigenetic Unit, IRCCS-Regina Elena National Cancer Institute, via Elio Chianesi 53, 00144, Rome, Italy
| | - Valentina Buemi
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy.,Department of Life Sciences, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Antonina Zappone
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy.,Department of Life Sciences, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Odessa Schillaci
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy
| | - Pamela Veneziano Broccia
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy.,Department of Life Sciences, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Roberto Dinami
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy.,Department of Life Sciences, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.,Oncogenomic and Epigenetic Unit, IRCCS-Regina Elena National Cancer Institute, via Elio Chianesi 53, 00144, Rome, Italy
| | - Silvia Matteoni
- Cellular Networks and Molecular Therapeutic Targets, Proteomics Unit, IRCCS-Regina Elena National Cancer Institute, via Elio Chianesi 53, 00144, Rome, Italy
| | - Roberta Benetti
- Dipartimento di Area Medica (Dame), Università degli Studi di Udine, p.le Kolbe 1, 33100, Udine, Italy.,Cancer Epigenetics Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy
| | - Stefan Schoeftner
- Genomic Stability Unit, Laboratorio Nazionale-Consorzio Interuniversitario per le Biotecnologie (LNCIB), Padriciano 99, 34149, Trieste, Italy. .,Department of Life Sciences, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.
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23
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Briggs E, Crouch K, Lemgruber L, Lapsley C, McCulloch R. Ribonuclease H1-targeted R-loops in surface antigen gene expression sites can direct trypanosome immune evasion. PLoS Genet 2018; 14:e1007729. [PMID: 30543624 PMCID: PMC6292569 DOI: 10.1371/journal.pgen.1007729] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/01/2018] [Indexed: 11/19/2022] Open
Abstract
Switching of the Variant Surface Glycoprotein (VSG) in Trypanosoma brucei provides a crucial host immune evasion strategy that is catalysed both by transcription and recombination reactions, each operating within specialised telomeric VSG expression sites (ES). VSG switching is likely triggered by events focused on the single actively transcribed ES, from a repertoire of around 15, but the nature of such events is unclear. Here we show that RNA-DNA hybrids, called R-loops, form preferentially within sequences termed the 70 bp repeats in the actively transcribed ES, but spread throughout the active and inactive ES, in the absence of RNase H1, which degrades R-loops. Loss of RNase H1 also leads to increased levels of VSG coat switching and replication-associated genome damage, some of which accumulates within the active ES. This work indicates VSG ES architecture elicits R-loop formation, and that these RNA-DNA hybrids connect T. brucei immune evasion by transcription and recombination.
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Affiliation(s)
- Emma Briggs
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Glasgow, United Kingdom
| | - Kathryn Crouch
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Glasgow, United Kingdom
| | - Leandro Lemgruber
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Glasgow, United Kingdom
| | - Craig Lapsley
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Glasgow, United Kingdom
| | - Richard McCulloch
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Glasgow, United Kingdom
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24
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Walker C, El-Khamisy SF. Perturbed autophagy and DNA repair converge to promote neurodegeneration in amyotrophic lateral sclerosis and dementia. Brain 2018; 141:1247-1262. [PMID: 29584802 PMCID: PMC5917746 DOI: 10.1093/brain/awy076] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 01/16/2018] [Accepted: 02/09/2018] [Indexed: 12/13/2022] Open
Abstract
Maintaining genomic stability constitutes a major challenge facing cells. DNA breaks can arise from direct oxidative damage to the DNA backbone, the inappropriate activities of endogenous enzymes such as DNA topoisomerases, or due to transcriptionally-derived RNA/DNA hybrids (R-loops). The progressive accumulation of DNA breaks has been linked to several neurological disorders. Recently, however, several independent studies have implicated nuclear and mitochondrial genomic instability, perturbed co-transcriptional processing, and impaired cellular clearance pathways as causal and intertwined mechanisms underpinning neurodegeneration. Here, we discuss this emerging paradigm in the context of amyotrophic lateral sclerosis and frontotemporal dementia, and outline how this knowledge paves the way to novel therapeutic interventions.
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Affiliation(s)
- Callum Walker
- Krebs Institute, Department of Molecular biology and biotechnology, University of Sheffield, UK
- The Institute of Cancer Research, London, UK
| | - Sherif F El-Khamisy
- Krebs Institute, Department of Molecular biology and biotechnology, University of Sheffield, UK
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
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25
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Kotsantis P, Petermann E, Boulton SJ. Mechanisms of Oncogene-Induced Replication Stress: Jigsaw Falling into Place. Cancer Discov 2018; 8:537-555. [PMID: 29653955 DOI: 10.1158/2159-8290.cd-17-1461] [Citation(s) in RCA: 232] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/26/2018] [Accepted: 03/09/2018] [Indexed: 12/31/2022]
Abstract
Oncogene activation disturbs cellular processes and accommodates a complex landscape of changes in the genome that contribute to genomic instability, which accelerates mutation rates and promotes tumorigenesis. Part of this cellular turmoil involves deregulation of physiologic DNA replication, widely described as replication stress. Oncogene-induced replication stress is an early driver of genomic instability and is attributed to a plethora of factors, most notably aberrant origin firing, replication-transcription collisions, reactive oxygen species, and defective nucleotide metabolism.Significance: Replication stress is a fundamental step and an early driver of tumorigenesis and has been associated with many activated oncogenes. Deciphering the mechanisms that contribute to the replication stress response may provide new avenues for targeted cancer treatment. In this review, we discuss the latest findings on the DNA replication stress response and examine the various mechanisms through which activated oncogenes induce replication stress. Cancer Discov; 8(5); 537-55. ©2018 AACR.
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Affiliation(s)
| | - Eva Petermann
- Institute of Cancer and Genomic Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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26
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Cdc73 suppresses genome instability by mediating telomere homeostasis. PLoS Genet 2018; 14:e1007170. [PMID: 29320491 PMCID: PMC5779705 DOI: 10.1371/journal.pgen.1007170] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 01/23/2018] [Accepted: 12/25/2017] [Indexed: 12/18/2022] Open
Abstract
Defects in the genes encoding the Paf1 complex can cause increased genome instability. Loss of Paf1, Cdc73, and Ctr9, but not Rtf1 or Leo1, caused increased accumulation of gross chromosomal rearrangements (GCRs). Combining the cdc73Δ mutation with individual deletions of 43 other genes, including TEL1 and YKU80, which are involved in telomere maintenance, resulted in synergistic increases in GCR rates. Whole genome sequence analysis of GCRs indicated that there were reduced relative rates of GCRs mediated by de novo telomere additions and increased rates of translocations and inverted duplications in cdc73Δ single and double mutants. Analysis of telomere lengths and telomeric gene silencing in strains containing different combinations of cdc73Δ, tel1Δ and yku80Δ mutations suggested that combinations of these mutations caused increased defects in telomere maintenance. A deletion analysis of Cdc73 revealed that a central 105 amino acid region was necessary and sufficient for suppressing the defects observed in cdc73Δ strains; this region was required for the binding of Cdc73 to the Paf1 complex through Ctr9 and for nuclear localization of Cdc73. Taken together, these data suggest that the increased GCR rate of cdc73Δ single and double mutants is due to partial telomere dysfunction and that Ctr9 and Paf1 play a central role in the Paf1 complex potentially by scaffolding the Paf1 complex subunits or by mediating recruitment of the Paf1 complex to the different processes it functions in. Maintaining a stable genome is crucial for all organisms, and loss of genome stability has been linked to multiple human diseases, including many cancers. Previously we found that defects in Cdc73, a component of the Paf1 transcriptional elongation complex, give rise to increased genome instability. Here, we explored the mechanism underlying this instability and found that Cdc73 defects give rise to partial defects in maintaining telomeres, which are the specialized ends of chromosomes, and interact with other mutations causing telomere defects. Remarkably, Cdc73 function is mediated through a short central region of the protein that is not a part of previously identified protein domains but targets Cdc73 to the Paf1 complex through interaction with the Ctr9 subunit. Analysis of the other components of the Paf1 complex provides a model in which the Paf1 subunit mediates recruitment of the other subunits to different processes they function in. Together, these data suggest that the mutations in CDC73 and CTR9 found in patients with hyperparathyroidism-jaw tumor syndrome and some patients with Wilms tumors, respectively, may contribute to cancer progression by contributing to genome instability.
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Abstract
During transcription, the nascent transcript behind an elongating RNA polymerase (RNAP) can invade the DNA duplex and hybridize with the complementary DNA template strand, generating a three-stranded "R-loop" structure, composed of an RNA:DNA duplex and an unpaired non-template DNA strand. R-loops can be strongly associated with actively transcribed loci by all RNAPs including the mitochondrial RNA polymerase (mtRNAP). In this chapter, we describe two protocols for the detection of RNA:DNA hybrids in living budding yeast cells, one that uses conventional chromatin immunoprecipitation (ChIP-qPCR) and one that uses DNA:RNA immunoprecipitation (DRIP-qPCR). Both protocols make use of the S9.6 antibody, which is believed to recognize the intermediate A/B helical RNA:DNA duplex conformation, with no sequence specificity.
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Affiliation(s)
- Aziz El Hage
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK.
| | - David Tollervey
- Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
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28
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Chen G, Magis AT, Xu K, Park D, Yu DS, Owonikoko TK, Sica GL, Satola SW, Ramalingam SS, Curran WJ, Doetsch PW, Deng X. Targeting Mcl-1 enhances DNA replication stress sensitivity to cancer therapy. J Clin Invest 2017; 128:500-516. [PMID: 29227281 DOI: 10.1172/jci92742] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 11/02/2017] [Indexed: 12/21/2022] Open
Abstract
DNA double-strand breaks (DSBs) are mainly repaired either by homologous recombination (HR) or by nonhomologous end-joining (NHEJ) pathways. Here, we showed that myeloid cell leukemia sequence 1 (Mcl-1) acts as a functional switch in selecting between HR and NHEJ pathways. Mcl-1 was cell cycle-regulated during HR, with its expression peaking in S/G2 phase. While endogenous Mcl-1 depletion reduced HR and enhanced NHEJ, Mcl-1 overexpression resulted in a net increase in HR over NHEJ. Mcl-1 directly interacted with the dimeric Ku protein complex via its Bcl-2 homology 1 and 3 (BH1 and BH3) domains, which are required for Mcl-1 to inhibit Ku-mediated NHEJ. Mcl-1 also promoted DNA resection mediated by the Mre11 complex and HR-dependent DSB repair. Using the Mcl-1 BH1 domain as a docking site, we identified a small molecule, MI-223, that directly bound to BH1 and blocked Mcl-1-stimulated HR DNA repair, leading to sensitization of cancer cells to hydroxyurea- or olaparib-induced DNA replication stress. Combined treatment with MI-223 and hydroxyurea or olaparib exhibited a strong synergy against lung cancer in vivo. This mechanism-driven combination of agents provides a highly attractive therapeutic strategy to improve lung cancer outcomes.
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Affiliation(s)
- Guo Chen
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
| | | | - Ke Xu
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
| | - Dongkyoo Park
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
| | - David S Yu
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
| | | | | | | | | | - Walter J Curran
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
| | - Paul W Doetsch
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA.,Department of Biochemistry, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
| | - Xingming Deng
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
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29
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Colombo CV, Trovesi C, Menin L, Longhese MP, Clerici M. The RNA binding protein Npl3 promotes resection of DNA double-strand breaks by regulating the levels of Exo1. Nucleic Acids Res 2017; 45:6530-6545. [PMID: 28472517 PMCID: PMC5499764 DOI: 10.1093/nar/gkx347] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/21/2017] [Indexed: 12/29/2022] Open
Abstract
Eukaryotic cells preserve genome integrity upon DNA damage by activating a signaling network that promotes DNA repair and controls cell cycle progression. One of the most severe DNA damage is the DNA double-strand break (DSB), whose 5΄ ends can be nucleolitically resected by multiple nucleases to create 3΄-ended single-stranded DNA tails that trigger DSB repair by homologous recombination. Here, we identify the Saccharomyces cerevisiae RNA binding protein Npl3 as a new player in DSB resection. Npl3 is related to both the metazoan serine-arginine-rich and the heterogeneous nuclear ribonucleo-proteins. NPL3 deletion impairs the generation of long ssDNA tails at the DSB ends, whereas it does not exacerbate the resection defect of exo1Δ cells. Furthermore, either the lack of Npl3 or the inactivation of its RNA-binding domains causes decrease of the exonuclease Exo1 protein levels as well as generation of unusual and extended EXO1 RNA species. These findings, together with the observation that EXO1 overexpression partially suppresses the resection defect of npl3Δ cells, indicate that Npl3 participates in DSB resection by promoting the proper biogenesis of EXO1 mRNA.
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Affiliation(s)
- Chiara Vittoria Colombo
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | - Camilla Trovesi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | - Luca Menin
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | - Michela Clerici
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
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30
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Auboeuf D. Alternative mRNA processing sites decrease genetic variability while increasing functional diversity. Transcription 2017; 9:75-87. [PMID: 29099315 PMCID: PMC5834221 DOI: 10.1080/21541264.2017.1373891] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Recent large-scale RNA sequencing efforts have revealed the extensive diversity of mRNA molecules produced from most eukaryotic coding genes, which arises from the usage of alternative, cryptic or non-canonical splicing and intronic polyadenylation sites. The prevailing view regarding the tremendous diversity of coding gene transcripts is that mRNA processing is a flexible and more-or-less noisy process leading to a diversity of proteins on which natural selection can act depending on protein-mediated cellular functions. However, this concept raises two main questions. First, do alternative mRNA processing pathways have a role other than generating mRNA and protein diversity? Second, is the cellular function of mRNA variants restricted to the biogenesis of functional protein isoforms? Here, I propose that the co-transcriptional use of alternative mRNA processing sites allows first, the resolution of co-transcriptional biophysical constraints that may otherwise result in DNA instability, and second, increases the diversity of cellular functions of mRNAs in a manner that is not restricted to protein synthesis.
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Affiliation(s)
- Didier Auboeuf
- a Univ Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Laboratory of Biology and Modelling of the Cell , 46 Allée d'Italie Site Jacques Monod, Lyon , France
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31
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Chang EYC, Novoa CA, Aristizabal MJ, Coulombe Y, Segovia R, Chaturvedi R, Shen Y, Keong C, Tam AS, Jones SJM, Masson JY, Kobor MS, Stirling PC. RECQ-like helicases Sgs1 and BLM regulate R-loop-associated genome instability. J Cell Biol 2017; 216:3991-4005. [PMID: 29042409 PMCID: PMC5716281 DOI: 10.1083/jcb.201703168] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/16/2017] [Accepted: 09/18/2017] [Indexed: 01/01/2023] Open
Abstract
Sgs1, the orthologue of human Bloom's syndrome helicase BLM, is a yeast DNA helicase functioning in DNA replication and repair. We show that SGS1 loss increases R-loop accumulation and sensitizes cells to transcription-replication collisions. Yeast lacking SGS1 accumulate R-loops and γ-H2A at sites of Sgs1 binding, replication pausing regions, and long genes. The mutation signature of sgs1Δ reveals copy number changes flanked by repetitive regions with high R-loop-forming potential. Analysis of BLM in Bloom's syndrome fibroblasts or by depletion of BLM from human cancer cells confirms a role for Sgs1/BLM in suppressing R-loop-associated genome instability across species. In support of a potential direct effect, BLM is found physically proximal to DNA:RNA hybrids in human cells, and can efficiently unwind R-loops in vitro. Together, our data describe a conserved role for Sgs1/BLM in R-loop suppression and support an increasingly broad view of DNA repair and replication fork stabilizing proteins as modulators of R-loop-mediated genome instability.
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Affiliation(s)
| | - Carolina A Novoa
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
| | | | - Yan Coulombe
- Genome Stability Laboratory, Centre Hospitalier Universitaire de Québec Research Center, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Romulo Segovia
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
| | - Richa Chaturvedi
- Genome Stability Laboratory, Centre Hospitalier Universitaire de Québec Research Center, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Yaoqing Shen
- Michael Smith Genome Sciences Centre, Vancouver, Canada
| | - Christelle Keong
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada
| | - Annie S Tam
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Steven J M Jones
- Michael Smith Genome Sciences Centre, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, Centre Hospitalier Universitaire de Québec Research Center, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Michael S Kobor
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Peter C Stirling
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada .,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
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32
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Physical proximity of chromatin to nuclear pores prevents harmful R loop accumulation contributing to maintain genome stability. Proc Natl Acad Sci U S A 2017; 114:10942-10947. [PMID: 28973905 DOI: 10.1073/pnas.1707845114] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During transcription, the mRNA may hybridize with DNA, forming an R loop, which can be physiological or pathological, constituting in this case a source of genomic instability. To understand the mechanism by which eukaryotic cells prevent harmful R loops, we used human activation-induced cytidine deaminase (AID) to identify genes preventing R loops. A screening of 400 Saccharomyces cerevisiae selected strains deleted in nuclear genes revealed that cells lacking the Mlp1/2 nuclear basket proteins show AID-dependent genomic instability and replication defects that were suppressed by RNase H1 overexpression. Importantly, DNA-RNA hybrids accumulated at transcribed genes in mlp1/2 mutants, indicating that Mlp1/2 prevents R loops. Consistent with the Mlp1/2 role in gene gating to nuclear pores, artificial tethering to the nuclear periphery of a transcribed locus suppressed R loops in mlp1∆ cells. The same occurred in THO-deficient hpr1∆ cells. We conclude that proximity of transcribed chromatin to the nuclear pore helps restrain pathological R loops.
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33
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García-Pichardo D, Cañas JC, García-Rubio ML, Gómez-González B, Rondón AG, Aguilera A. Histone Mutants Separate R Loop Formation from Genome Instability Induction. Mol Cell 2017; 66:597-609.e5. [PMID: 28575656 DOI: 10.1016/j.molcel.2017.05.014] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 04/03/2017] [Accepted: 05/15/2017] [Indexed: 01/02/2023]
Abstract
R loops have positive physiological roles, but they can also be deleterious by causing genome instability, and the mechanisms for this are unknown. Here we identified yeast histone H3 and H4 mutations that facilitate R loops but do not cause instability. R loops containing single-stranded DNA (ssDNA), versus RNA-DNA hybrids alone, were demonstrated using ssDNA-specific human AID and bisulfite. Notably, they are similar size regardless of whether or not they induce genome instability. Contrary to mutants causing R loop-mediated instability, these histone mutants do not accumulate H3 serine-10 phosphate (H3S10-P). We propose a two-step mechanism in which, first, an altered chromatin facilitates R loops, and second, chromatin is modified, including H3S10-P, as a requisite for compromising genome integrity. Consistently, these histone mutations suppress the high H3S10 phosphorylation and genomic instability of hpr1 and sen1 mutants. Therefore, contrary to what was previously believed, R loops do not cause genome instability by themselves.
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Affiliation(s)
- Desiré García-Pichardo
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Juan C Cañas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - María L García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Ana G Rondón
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville 41092, Spain.
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34
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Bonnet A, Grosso AR, Elkaoutari A, Coleno E, Presle A, Sridhara SC, Janbon G, Géli V, de Almeida SF, Palancade B. Introns Protect Eukaryotic Genomes from Transcription-Associated Genetic Instability. Mol Cell 2017; 67:608-621.e6. [PMID: 28757210 DOI: 10.1016/j.molcel.2017.07.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 05/19/2017] [Accepted: 06/30/2017] [Indexed: 12/31/2022]
Abstract
Transcription is a source of genetic instability that can notably result from the formation of genotoxic DNA:RNA hybrids, or R-loops, between the nascent mRNA and its template. Here we report an unexpected function for introns in counteracting R-loop accumulation in eukaryotic genomes. Deletion of endogenous introns increases R-loop formation, while insertion of an intron into an intronless gene suppresses R-loop accumulation and its deleterious impact on transcription and recombination in yeast. Recruitment of the spliceosome onto the mRNA, but not splicing per se, is shown to be critical to attenuate R-loop formation and transcription-associated genetic instability. Genome-wide analyses in a number of distant species differing in their intron content, including human, further revealed that intron-containing genes and the intron-richest genomes are best protected against R-loop accumulation and subsequent genetic instability. Our results thereby provide a possible rationale for the conservation of introns throughout the eukaryotic lineage.
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Affiliation(s)
- Amandine Bonnet
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Ana R Grosso
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1600-276 Lisboa, Portugal
| | - Abdessamad Elkaoutari
- Cancer Research Center of Marseille (CRCM), Equipe Labellisée Ligue, U1068 INSERM, UMR7258 CNRS, Institut Paoli-Calmettes, Aix Marseille University, 13284 Marseille, France
| | - Emeline Coleno
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Adrien Presle
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Sreerama C Sridhara
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1600-276 Lisboa, Portugal
| | - Guilhem Janbon
- Institut Pasteur, Unité Biologie des ARN des Pathogènes Fongiques, Département de Mycologie, 75015 Paris, France
| | - Vincent Géli
- Cancer Research Center of Marseille (CRCM), Equipe Labellisée Ligue, U1068 INSERM, UMR7258 CNRS, Institut Paoli-Calmettes, Aix Marseille University, 13284 Marseille, France
| | - Sérgio F de Almeida
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1600-276 Lisboa, Portugal
| | - Benoit Palancade
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France.
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35
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Nishida K, Kuwano Y, Nishikawa T, Masuda K, Rokutan K. RNA Binding Proteins and Genome Integrity. Int J Mol Sci 2017; 18:E1341. [PMID: 28644387 PMCID: PMC5535834 DOI: 10.3390/ijms18071341] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 06/16/2017] [Accepted: 06/20/2017] [Indexed: 01/10/2023] Open
Abstract
Genome integrity can be threatened by various endogenous or exogenous events. To counteract these stressors, the DNA damage response network contributes to the prevention and/or repair of genomic DNA damage and serves an essential function in cellular survival. DNA binding proteins are involved in this network. Recently, several RNA-binding proteins (RBPs) that are recruited to DNA damage sites have been shown to be direct players in the prevention or repair of DNA damage. In addition, non-coding RNAs, themselves, are involved in the RNA-mediated DNA repair system. Furthermore, RNA modification such as m6A methylation might also contribute to the ultraviolet-responsive DNA damage response. Accumulating evidence suggests that RNA metabolism is more deeply involved in diverse cellular functions than previously expected, and is also intricately associated with the maintenance of genome integrity. In this review, we highlight the roles of RBPs in the maintenance of genome integrity.
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Affiliation(s)
- Kensei Nishida
- Department of Pathophysiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan.
| | - Yuki Kuwano
- Department of Pathophysiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan.
| | - Tatsuya Nishikawa
- Department of Pathophysiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan.
| | - Kiyoshi Masuda
- Department of Human Genetics, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan.
| | - Kazuhito Rokutan
- Department of Pathophysiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan.
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36
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The Chromatin Remodeler ISW1 Is a Quality Control Factor that Surveys Nuclear mRNP Biogenesis. Cell 2017; 167:1201-1214.e15. [PMID: 27863241 DOI: 10.1016/j.cell.2016.10.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 09/12/2016] [Accepted: 10/27/2016] [Indexed: 02/07/2023]
Abstract
Chromatin dynamics play an essential role in regulating DNA transaction processes, but it is unclear whether transcription-associated chromatin modifications control the mRNA ribonucleoparticles (mRNPs) pipeline from synthesis to nuclear exit. Here, we identify the yeast ISW1 chromatin remodeling complex as an unanticipated mRNP nuclear export surveillance factor that retains export-incompetent transcripts near their transcription site. This tethering activity of ISW1 requires chromatin binding and is independent of nucleosome sliding activity or changes in RNA polymerase II processivity. Combination of in vivo UV-crosslinking and genome-wide RNA immunoprecipitation assays show that Isw1 and its cofactors interact directly with premature mRNPs. Our results highlight that the concerted action of Isw1 and the nuclear exosome ensures accurate surveillance mechanism that proofreads the efficiency of mRNA biogenesis.
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37
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Gómez-Navarro N, Peiró-Chova L, Estruch F. Iwr1 facilitates RNA polymerase II dynamics during transcription elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:803-811. [PMID: 28258010 DOI: 10.1016/j.bbagrm.2017.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 02/16/2017] [Accepted: 02/27/2017] [Indexed: 11/16/2022]
Abstract
Iwr1 is an RNA polymerase II (RNPII) interacting protein that directs nuclear import of the enzyme which has been previously assembled in the cytoplasm. Here we present genetic and molecular evidence that links Iwr1 with transcription. Our results indicate that Iwr1 interacts with RNPII during elongation and is involved in the disassembly of the enzyme from chromatin. This function is especially important in resolving problems posed by damage-arrested RNPII, as shown by the sensitivity of iwr1 mutants to genotoxic drugs and the Iwr1's genetic interactions with RNPII degradation pathway mutants. Moreover, absence of Iwr1 causes genome instability that is enhanced by defects in the DNA repair machinery.
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Affiliation(s)
- Natalia Gómez-Navarro
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain
| | - Lorena Peiró-Chova
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain
| | - Francisco Estruch
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain.
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38
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Abstract
DNA topological transitions occur when replication forks encounter other DNA transactions such as transcription. Failure in resolving such conflicts leads to generation of aberrant replication and transcription intermediates that might have adverse effects on genome stability. Cells have evolved numerous surveillance mechanisms to avoid, tolerate, and resolve such replication-transcription conflicts. Defects or non-coordination in such cellular mechanisms might have catastrophic effect on cell viability. In this chapter, we review consequences of replication encounters with transcription and its associated events, topological challenges, and how these inevitable conflicts alter the genome structure and functions.
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39
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The spliceosome U2 snRNP factors promote genome stability through distinct mechanisms; transcription of repair factors and R-loop processing. Oncogenesis 2016; 5:e280. [PMID: 27991914 PMCID: PMC5177769 DOI: 10.1038/oncsis.2016.70] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 10/02/2016] [Indexed: 12/12/2022] Open
Abstract
Recent whole-exome sequencing of malignancies have detected recurrent somatic mutations in U2 small nuclear ribonucleoprotein complex (snRNP) components of the spliceosome. These factors have also been identified as novel players in the DNA-damage response (DDR) in several genome-wide screens and proteomic analysis. Although accumulating evidence implies that the spliceosome has an important role in genome stability and is an emerging hallmark of cancer, its precise role in DNA repair still remains elusive. Here we identify two distinct mechanisms of how spliceosome U2 snRNP factors contribute to genome stability. We show that the spliceosome maintains protein levels of essential repair factors, thus contributing to homologous recombination repair. In addition, real-time laser microirradiation analysis identified rapid recruitment of the U2 snRNP factor SNRPA1 to DNA-damage sites. Functional analysis of SNRPA1 revealed a more immediate and direct role in preventing R-loop-induced DNA damage. Our present study implies a complex interrelation between transcription, mRNA splicing and the DDR. Cells require rapid spatio-temporal coordination of these chromatin transactions to cope with various forms of genotoxic stress.
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40
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Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes. Nat Struct Mol Biol 2016; 24:162-170. [PMID: 27991904 PMCID: PMC5296403 DOI: 10.1038/nsmb.3342] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/14/2016] [Indexed: 12/03/2022]
Abstract
Saccharomyces cerevisiae encodes two distinct Pif1-family helicases – Pif1 and Rrm3 – which have been reported to play distinct roles in numerous nuclear processes. Here, we systematically characterize the roles of Pif1 helicases in replisome progression and lagging-strand synthesis in S. cerevisiae. We demonstrate that either Pif1 or Rrm3 redundantly stimulate strand-displacement by DNA polymerase δ during lagging-strand synthesis. By analyzing replisome mobility in pif1 and rrm3 mutants, we show that Rrm3, with a partially redundant contribution from Pif1, suppresses widespread terminal arrest of the replisome at tRNA genes. Although both head-on and codirectional collisions induce replication fork arrest at tRNA genes, head-on collisions arrest a higher proportion of replisomes. Consistent with this observation, we find that head-on collisions between tRNA transcription and replication are under-represented in the S. cerevisiae genome. We demonstrate that tRNA-mediated arrest is R-loop independent, and propose that replisome arrest and DNA damage are mechanistically separable.
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41
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Abraham KJ, Chan JNY, Salvi JS, Ho B, Hall A, Vidya E, Guo R, Killackey SA, Liu N, Lee JE, Brown GW, Mekhail K. Intersection of calorie restriction and magnesium in the suppression of genome-destabilizing RNA-DNA hybrids. Nucleic Acids Res 2016; 44:8870-8884. [PMID: 27574117 PMCID: PMC5063000 DOI: 10.1093/nar/gkw752] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/20/2016] [Indexed: 12/14/2022] Open
Abstract
Dietary calorie restriction is a broadly acting intervention that extends the lifespan of various organisms from yeast to mammals. On another front, magnesium (Mg2+) is an essential biological metal critical to fundamental cellular processes and is commonly used as both a dietary supplement and treatment for some clinical conditions. If connections exist between calorie restriction and Mg2+ is unknown. Here, we show that Mg2+, acting alone or in response to dietary calorie restriction, allows eukaryotic cells to combat genome-destabilizing and lifespan-shortening accumulations of RNA–DNA hybrids, or R-loops. In an R-loop accumulation model of Pbp1-deficient Saccharomyces cerevisiae, magnesium ions guided by cell membrane Mg2+ transporters Alr1/2 act via Mg2+-sensitive R-loop suppressors Rnh1/201 and Pif1 to restore R-loop suppression, ribosomal DNA stability and cellular lifespan. Similarly, human cells deficient in ATXN2, the human ortholog of Pbp1, exhibit nuclear R-loop accumulations repressible by Mg2+ in a process that is dependent on the TRPM7 Mg2+ transporter and the RNaseH1 R-loop suppressor. Thus, we identify Mg2+ as a biochemical signal of beneficial calorie restriction, reveal an R-loop suppressing function for human ATXN2 and propose that practical magnesium supplementation regimens can be used to combat R-loop accumulation linked to the dysfunction of disease-linked human genes.
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Affiliation(s)
- Karan J Abraham
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Janet N Y Chan
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Jayesh S Salvi
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Brandon Ho
- Department of Biochemistry and Donnelly Centre, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Amanda Hall
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Elva Vidya
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Ru Guo
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Samuel A Killackey
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Nancy Liu
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Jeffrey E Lee
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada Canada Research Chairs Program, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Grant W Brown
- Department of Biochemistry and Donnelly Centre, University of Toronto, 160 College Street, Toronto, ON M5S 3E1, Canada
| | - Karim Mekhail
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada Canada Research Chairs Program, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
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42
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Stork CT, Bocek M, Crossley MP, Sollier J, Sanz LA, Chédin F, Swigut T, Cimprich KA. Co-transcriptional R-loops are the main cause of estrogen-induced DNA damage. eLife 2016; 5. [PMID: 27552054 PMCID: PMC5030092 DOI: 10.7554/elife.17548] [Citation(s) in RCA: 184] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/18/2016] [Indexed: 12/19/2022] Open
Abstract
The hormone estrogen (E2) binds the estrogen receptor to promote transcription of E2-responsive genes in the breast and other tissues. E2 also has links to genomic instability, and elevated E2 levels are tied to breast cancer. Here, we show that E2 stimulation causes a rapid, global increase in the formation of R-loops, co-transcriptional RNA-DNA products, which in some instances have been linked to DNA damage. We show that E2-dependent R-loop formation and breast cancer rearrangements are highly enriched at E2-responsive genomic loci and that E2 induces DNA replication-dependent double-strand breaks (DSBs). Strikingly, many DSBs that accumulate in response to E2 are R-loop dependent. Thus, R-loops resulting from the E2 transcriptional response are a significant source of DNA damage. This work reveals a novel mechanism by which E2 stimulation leads to genomic instability and highlights how transcriptional programs play an important role in shaping the genomic landscape of DNA damage susceptibility. DOI:http://dx.doi.org/10.7554/eLife.17548.001 The hormone estrogen controls the development of breast tissue. However too much estrogen can damage the DNA in human cells and may be linked to an increased risk of breast cancer. In breast cells, estrogen activates many genes via a process called transcription. The transcription process results in the production of an RNA molecule that contains a copy of the instructions encoded within the gene. Previous studies have found that, in certain cases, a new RNA molecule can stick to the matching DNA from which it was made. This creates a structure known as an R-loop, which can lead the DNA to break. DNA breaks are particularly harmful because they can dramatically alter the cell’s genome in ways that allow it to become cancerous. However, it was not clear if the large increase in transcription triggered by estrogen causes an increase in R-loops, which could help to explain the DNA damage that has been reported to occur when cells are treated with estrogen. Now, Stork et al. show that treating human breast cancer cells with estrogen causes an increase in R-loops and DNA breaks. The R-loops occurred particularly in regions of the genome that contain estrogen-activated genes. Stork et al. also found that regions of estrogen-activated transcription were more frequently mutated in breast cancers, and further experiments confirmed that the R-loops were responsible for many of the DNA breaks that occurred following estrogen treatment. Taken together, these findings demonstrate that the changes in transcription due to estrogen lead to increased R-loops and DNA breaks, which may make the cells vulnerable to becoming cancerous. The next challenge is to determine precisely where these DNA breaks that result from estrogen occur on the DNA. Knowing the location of the DNA breaks will be useful in determining what additional factors or genomic features make an R-loop more prone to being broken. This in turn might help explain how the R-loops lead to DNA damage. In addition, further studies are also needed to determine if tumor samples from breast cancer patients also contain increased levels of R-loops. DOI:http://dx.doi.org/10.7554/eLife.17548.002
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Affiliation(s)
- Caroline Townsend Stork
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Michael Bocek
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Madzia P Crossley
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Julie Sollier
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Lionel A Sanz
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Tomek Swigut
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Karlene A Cimprich
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
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43
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Canonical DNA Repair Pathways Influence R-Loop-Driven Genome Instability. J Mol Biol 2016; 429:3132-3138. [PMID: 27452366 DOI: 10.1016/j.jmb.2016.07.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/05/2016] [Accepted: 07/12/2016] [Indexed: 12/22/2022]
Abstract
DNA repair defects create cancer predisposition in humans by fostering a higher rate of mutations. While DNA repair is quite well characterized, recent studies have identified previously unrecognized relationships between DNA repair and R-loop-mediated genome instability. R-loops are three-stranded nucleic acid structures in which RNA binds to genomic DNA to displace a loop of single-stranded DNA. Mutations in homologous recombination, nucleotide excision repair, crosslink repair, and DNA damage checkpoints have all now been linked to formation and function of transcription-coupled R-loops. This perspective will summarize recent literature linking DNA repair to R-loop-mediated genomic instability and discuss how R-loops may contribute to mutagenesis in DNA-repair-deficient cancers.
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44
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Al-Hadid Q, Yang Y. R-loop: an emerging regulator of chromatin dynamics. Acta Biochim Biophys Sin (Shanghai) 2016; 48:623-31. [PMID: 27252122 DOI: 10.1093/abbs/gmw052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/29/2016] [Indexed: 12/27/2022] Open
Abstract
The dynamic structure of chromatin, which exists in two conformational states: heterochromatin and euchromatin, alters the accessibility of the DNA to regulatory factors during transcription, replication, recombination, and DNA damage repair. Chemical modifications of histones and DNA, as well as adenosine triphospahate-dependent nucleosome remodeling, have been the major focus of research on chromatin dynamics over the past two decades. However, recent studies using a DNA-RNA hybrid-specific antibody and next-generation sequencing approaches have revealed that the formation of R-loops, one of the most common non-canonical DNA structures, is an emerging regulator of chromatin states. This review focuses on recent insights into the interplay between R-loop formation and the epigenetic modifications of chromatin in normal and disease states.
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Affiliation(s)
- Qais Al-Hadid
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Cancer Center, Duarte, CA 91010, USA
| | - Yanzhong Yang
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope Cancer Center, Duarte, CA 91010, USA
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45
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Long non-coding RNAs in cancer drug resistance development. DNA Repair (Amst) 2016; 45:25-33. [PMID: 27427176 DOI: 10.1016/j.dnarep.2016.06.003] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 06/29/2016] [Accepted: 06/29/2016] [Indexed: 02/06/2023]
Abstract
The presence or emergence of chemoresistance in tumor cells is a major burden in cancer therapy. While drug resistance is a multifactorial phenomenon arising from altered membrane transport of drugs, altered drug metabolism, altered DNA repair, reduced apoptosis rate and alterations of drug metabolism, it can also be linked to genetic and epigenetic factors. Long non-coding RNAs (lncRNAs) have important regulatory roles in many aspects of genome function including gene transcription, splicing, and epigenetics as well as biological processes involved in cell cycle, cell differentiation, development, and pluripotency. As such, it may not be surprising that some lncRNAs have been recently linked to carcinogenesis and drug resistance/sensitivity. Research is accelerating to decipher the exact molecular mechanism of lncRNA-regulated drug resistance and its therapeutic implications. In this article, we will review the structure, biogenesis, and mode of action of lncRNAs. Then, the involvement of lncRNAs in drug resistance will be discussed in detail.
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46
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Heterogeneous Nuclear Ribonucleoprotein L is required for the survival and functional integrity of murine hematopoietic stem cells. Sci Rep 2016; 6:27379. [PMID: 27271479 PMCID: PMC4895350 DOI: 10.1038/srep27379] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 05/16/2016] [Indexed: 12/15/2022] Open
Abstract
The proliferation and survival of hematopoietic stem cells (HSCs) has to be strictly coordinated to ensure the timely production of all blood cells. Here we report that the splice factor and RNA binding protein hnRNP L (heterogeneous nuclear ribonucleoprotein L) is required for hematopoiesis, since its genetic ablation in mice reduces almost all blood cell lineages and causes premature death of the animals. In agreement with this, we observed that hnRNP L deficient HSCs lack both the ability to self-renew and foster hematopoietic differentiation in transplanted hosts. They also display mitochondrial dysfunction, elevated levels of γH2AX, are Annexin V positive and incorporate propidium iodide indicating that they undergo cell death. Lin(-)c-Kit(+) fetal liver cells from hnRNP L deficient mice show high p53 protein levels and up-regulation of p53 target genes. In addition, cells lacking hnRNP L up-regulated the expression of the death receptors TrailR2 and CD95/Fas and show Caspase-3, Caspase-8 and Parp cleavage. Treatment with the pan-caspase inhibitor Z-VAD-fmk, but not the deletion of p53, restored cell survival in hnRNP L deficient cells. Our data suggest that hnRNP L is critical for the survival and functional integrity of HSCs by restricting the activation of caspase-dependent death receptor pathways.
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47
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Affiliation(s)
- Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, Sevilla 41092, Spain; ,
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, Sevilla 41092, Spain; ,
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48
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Gavaldá S, Santos-Pereira JM, García-Rubio ML, Luna R, Aguilera A. Excess of Yra1 RNA-Binding Factor Causes Transcription-Dependent Genome Instability, Replication Impairment and Telomere Shortening. PLoS Genet 2016; 12:e1005966. [PMID: 27035147 PMCID: PMC4818039 DOI: 10.1371/journal.pgen.1005966] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 03/09/2016] [Indexed: 11/19/2022] Open
Abstract
Yra1 is an essential nuclear factor of the evolutionarily conserved family of hnRNP-like export factors that when overexpressed impairs mRNA export and cell growth. To investigate further the relevance of proper Yra1 stoichiometry in the cell, we overexpressed Yra1 by transforming yeast cells with YRA1 intron-less constructs and analyzed its effect on gene expression and genome integrity. We found that YRA1 overexpression induces DNA damage and leads to a transcription-associated hyperrecombination phenotype that is mediated by RNA:DNA hybrids. In addition, it confers a genome-wide replication retardation as seen by reduced BrdU incorporation and accumulation of the Rrm3 helicase. In addition, YRA1 overexpression causes a cell senescence-like phenotype and telomere shortening. ChIP-chip analysis shows that overexpressed Yra1 is loaded to transcribed chromatin along the genome and to Y’ telomeric regions, where Rrm3 is also accumulated, suggesting an impairment of telomere replication. Our work not only demonstrates that a proper stoichiometry of the Yra1 mRNA binding and export factor is required to maintain genome integrity and telomere homeostasis, but suggests that the cellular imbalance between transcribed RNA and specific RNA-binding factors may become a major cause of genome instability mediated by co-transcriptional replication impairment. Yra1 is an essential nuclear RNA-binding protein that plays a role in mRNA export in Saccharomyces cerevisiae. The cellular levels of Yra1 are tightly auto-regulated by splicing of an unusual intron in its pre-mRNA, removal of which causes Yra1 overexpression that results in a dominant-negative growth defect and mRNA export defect. We wondered whether or not YRA1 overexpression has an effect on genome integrity that could explain the loss of cell viability. Our analyses reveal that YRA1 overexpression causes DNA damage, confers a hyperrecombination phenotype that depends on transcription and that is mediated by RNA:DNA hybrids. YRA1 overexpression also leads to a cell senescence-like phenotype and telomere shortening. We show by ChIP-chip analysis that Yra1 binds to active chromatin and Y’ telomeric regions when it is overexpressed, in agreement with a possible role of this mRNP factor in the maintenance of telomere integrity. Our data indicate that YRA1 overexpression correlates with replication impairment as inferred by the reduction of BrdU incorporation and the increase of Rrm3 recruitment, a helicase involved in replication fork progression, at transcribed genes and Y’ regions. We conclude that the stoichiometry of specific RNA-binding factors such as Yra1 at telomeres is critical for genome integrity and for preventing transcription-replication conflicts.
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Affiliation(s)
- Sandra Gavaldá
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | - José M. Santos-Pereira
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | - María L. García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | - Rosa Luna
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
- * E-mail: (AA); (RL)
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
- * E-mail: (AA); (RL)
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49
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Holmes RK, Tuck AC, Zhu C, Dunn-Davies HR, Kudla G, Clauder-Munster S, Granneman S, Steinmetz LM, Guthrie C, Tollervey D. Loss of the Yeast SR Protein Npl3 Alters Gene Expression Due to Transcription Readthrough. PLoS Genet 2015; 11:e1005735. [PMID: 26694144 PMCID: PMC4687934 DOI: 10.1371/journal.pgen.1005735] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/20/2015] [Indexed: 01/25/2023] Open
Abstract
Yeast Npl3 is a highly abundant, nuclear-cytoplasmic shuttling, RNA-binding protein, related to metazoan SR proteins. Reported functions of Npl3 include transcription elongation, splicing and RNA 3’ end processing. We used UV crosslinking and analysis of cDNA (CRAC) to map precise RNA binding sites, and strand-specific tiling arrays to look at the effects of loss of Npl3 on all transcripts across the genome. We found that Npl3 binds diverse RNA species, both coding and non-coding, at sites indicative of roles in both early pre-mRNA processing and 3’ end formation. Tiling arrays and RNAPII mapping data revealed 3’ extended RNAPII-transcribed RNAs in the absence of Npl3, suggesting that defects in pre-mRNA packaging events result in termination readthrough. Transcription readthrough was widespread and frequently resulted in down-regulation of neighboring genes. We conclude that the absence of Npl3 results in widespread 3' extension of transcripts with pervasive effects on gene expression. Npl3 is a yeast mRNA binding protein with many reported functions in RNA processing. We wanted to identify direct targets and therefore combined analyses of the transcriptome-wide effects of the loss of Npl3 on gene expression with UV crosslinking and bioinformatics to identify RNA-binding sites for Npl3. We found that Npl3 binds diverse sites on large numbers of transcripts, and that the loss of Npl3 results in transcriptional readthrough on many genes. One effect of this transcription readthrough is that the expression of numerous flanking genes is strongly down regulated. This underlines the importance of faithful termination for the correct regulation of gene expression. The effects of the loss of Npl3 are seen on both mRNAs and non-protein coding RNAs. These have distinct but overlapping termination mechanisms, with both classes requiring Npl3 for correct RNA packaging.
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Affiliation(s)
- Rebecca K. Holmes
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Alex C. Tuck
- FMI Basel, Basel, Switzerland
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | | | - Hywel R. Dunn-Davies
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Grzegorz Kudla
- The Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland, United Kingdom
| | | | - Sander Granneman
- SynthSys, University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | | | - Christine Guthrie
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - David Tollervey
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
- * E-mail:
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50
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Molla-Herman A, Vallés AM, Ganem-Elbaz C, Antoniewski C, Huynh JR. tRNA processing defects induce replication stress and Chk2-dependent disruption of piRNA transcription. EMBO J 2015; 34:3009-27. [PMID: 26471728 PMCID: PMC4687792 DOI: 10.15252/embj.201591006] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 09/01/2015] [Accepted: 09/04/2015] [Indexed: 02/01/2023] Open
Abstract
RNase P is a conserved endonuclease that processes the 5' trailer of tRNA precursors. We have isolated mutations in Rpp30, a subunit of RNase P, and find that these induce complete sterility in Drosophila females. Here, we show that sterility is not due to a shortage of mature tRNAs, but that atrophied ovaries result from the activation of several DNA damage checkpoint proteins, including p53, Claspin, and Chk2. Indeed, we find that tRNA processing defects lead to increased replication stress and de-repression of transposable elements in mutant ovaries. We also report that transcription of major piRNA sources collapse in mutant germ cells and that this correlates with a decrease in heterochromatic H3K9me3 marks on the corresponding piRNA-producing loci. Our data thus link tRNA processing, DNA replication, and genome defense by small RNAs. This unexpected connection reveals constraints that could shape genome organization during evolution.
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Affiliation(s)
- Anahi Molla-Herman
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| | - Ana Maria Vallés
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| | - Carine Ganem-Elbaz
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| | - Christophe Antoniewski
- GED, UPMC, CNRS UMR 7622, IBPS, Developmental Biology Laboratory (IBPS-LBD), Paris, France
| | - Jean-René Huynh
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
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