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Liang HT, Yan JY, Yao HJ, Zhang XN, Xing ZM, Liu L, Chen YQ, Li GR, Huang J, He YD, Zheng KW. G-quadruplexes on chromosomal DNA negatively regulates topoisomerase 1 activity. Nucleic Acids Res 2024; 52:2142-2156. [PMID: 38340342 PMCID: PMC10954455 DOI: 10.1093/nar/gkae073] [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: 10/21/2023] [Revised: 01/03/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Human DNA topoisomerase 1 (Top1) is a crucial enzyme responsible for alleviating torsional stress on DNA during transcription and replication, thereby maintaining genome stability. Previous researches had found that non-working Top1 interacted extensively with chromosomal DNA in human cells. However, the reason for its retention on chromosomal DNA remained unclear. In this study, we discovered a close association between Top1 and chromosomal DNA, specifically linked to the presence of G-quadruplex (G4) structures. G4 structures, formed during transcription, trap Top1 and hinder its ability to relax neighboring DNAs. Disruption of the Top1-G4 interaction using G4 ligand relieved the inhibitory effect of G4 on Top1 activity, resulting in a further reduction of R-loop levels in cells. Additionally, the activation of Top1 through the use of a G4 ligand enhanced the toxicity of Top1 inhibitors towards cancer cells. Our study uncovers a negative regulation mechanism of human Top1 and highlights a novel pathway for activating Top1.
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Affiliation(s)
- Hui-ting Liang
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
- School of Pharmaceutical Sciences, Shenzhen Campus of Sun Yat-Sen University, Shenzhen 518107, China
| | - Jiang-yu Yan
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
| | - Hao-jun Yao
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
| | - Xue-nan Zhang
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
| | - Zhi-ming Xing
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
| | - Lin Liu
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China
| | - Yao-qing Chen
- School of Public Health (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China
| | - Guo-rui Li
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
| | - Jing Huang
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
| | - Yi-de He
- School of Pharmaceutical Sciences, Shenzhen Campus of Sun Yat-Sen University, Shenzhen 518107, China
| | - Ke-wei Zheng
- School of Biomedical Sciences, Hunan University, Changsha 410082, China
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2
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Lista MJ, Jousset AC, Cheng M, Saint-André V, Perrot E, Rodrigues M, Di Primo C, Gadelle D, Toccafondi E, Segeral E, Berlioz-Torrent C, Emiliani S, Mergny JL, Lavigne M. DNA topoisomerase 1 represses HIV-1 promoter activity through its interaction with a guanine quadruplex present in the LTR sequence. Retrovirology 2023; 20:10. [PMID: 37254203 DOI: 10.1186/s12977-023-00625-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/20/2023] [Indexed: 06/01/2023] Open
Abstract
BACKGROUND Once integrated in the genome of infected cells, HIV-1 provirus is transcribed by the cellular transcription machinery. This process is regulated by both viral and cellular factors, which are necessary for an efficient viral replication as well as for the setting up of viral latency, leading to a repressed transcription of the integrated provirus. RESULTS In this study, we examined the role of two parameters in HIV-1 LTR promoter activity. We identified DNA topoisomerase1 (TOP1) to be a potent repressor of this promoter and linked this repression to its catalytic domain. Additionally, we confirmed the folding of a Guanine quadruplex (G4) structure in the HIV-1 promoter and its repressive effect. We demonstrated a direct interaction between TOP1 and this G4 structure, providing evidence of a functional relationship between the two repressive elements. Mutations abolishing G4 folding affected TOP1/G4 interaction and hindered G4-dependent inhibition of TOP1 catalytic activity in vitro. As a result, HIV-1 promoter activity was reactivated in a native chromatin environment. Lastly, we noticed an enrichment of predicted G4 sequences in the promoter of TOP1-repressed cellular genes. CONCLUSIONS Our results demonstrate the formation of a TOP1/G4 complex on the HIV-1 LTR promoter and its repressive effect on the promoter activity. They reveal the existence of a new mechanism of TOP1/G4-dependent transcriptional repression conserved between viral and human genes. This mechanism contrasts with the known property of TOP1 as global transcriptional activator and offers new perspectives for anti-cancer and anti-viral strategies.
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Affiliation(s)
- María José Lista
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King's College London, London, UK
| | - Anne-Caroline Jousset
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
- Université de Strasbourg, CNRS UPR 9002, Architecture et réactivité de l'ARN, 67000, Strasbourg, France
| | - Mingpan Cheng
- CNRS UMR 5320, INSERM U1212, ARNA, Univ. Bordeaux, IECB, 33000, Bordeaux, France
- School of Engineering, China Pharmaceutical University, Nanjing, 211198, China
| | - Violaine Saint-André
- Institut Pasteur, Bioinformatics and Biostatistics Hub, Université Paris Cité, 75015, Paris, France
| | - Elouan Perrot
- Institut Pasteur, Departement of Virology, Université Paris Cité, 75015, Paris, France
| | - Melissa Rodrigues
- Institut Pasteur, Departement of Virology, Université Paris Cité, 75015, Paris, France
| | - Carmelo Di Primo
- CNRS UMR 5320, INSERM U1212, ARNA, Univ. Bordeaux, IECB, 33000, Bordeaux, France
| | - Danielle Gadelle
- Institut de Biologie Integrative de la Cellule, CNRS, Université Paris-Saclay, 91198, Gif Sur Yvette, Cedex, France
| | - Elenia Toccafondi
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
- Université de Strasbourg, CNRS UPR 9002, Architecture et réactivité de l'ARN, 67000, Strasbourg, France
| | - Emmanuel Segeral
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
| | | | - Stéphane Emiliani
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014, Paris, France
| | - Jean-Louis Mergny
- CNRS UMR 5320, INSERM U1212, ARNA, Univ. Bordeaux, IECB, 33000, Bordeaux, France
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91120, Palaiseau, France
| | - Marc Lavigne
- Université Paris Cité, Institut Cochin, INSERM, CNRS, F-75014, Paris, France.
- Institut Pasteur, Departement of Virology, Université Paris Cité, 75015, Paris, France.
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3
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G4-interacting proteins endangering genomic stability at G4 DNA-forming sites. Biochem Soc Trans 2023; 51:403-413. [PMID: 36629511 PMCID: PMC10018705 DOI: 10.1042/bst20221018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/09/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
In guanine-rich DNA strands, base-base interactions among guanines allow the conformational shift from the B-form DNA to the non-canonical quadruplex or G4 structure. The functional significance of G4 DNA in vivo is largely dependent on the interaction with protein factors, many of which contain the arginine-glycine-glycine or RGG repeat and other consensus G4-binding motifs. These G4-interacting proteins can significantly modulate the effect of G4 DNA structure on genome maintenance, either preventing or aggravating G4-assoicated genome instability. While the role of helicases in resolving G4 DNA structure has been extensively discussed, identification and characterization of protein factors contributing to elevation in G4-associated genome instability has been relatively sparse. In this minireview, we will particularly highlight recent discoveries regarding how interaction between certain G4-binding proteins and G4 DNA could exacerbate genome instability potentiated by G4 DNA-forming sequences.
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4
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Keller JG, Hymøller KM, Thorsager ME, Hansen NY, Erlandsen JU, Tesauro C, Simonsen AKW, Andersen AB, VandsøPetersen K, Holm LL, Stougaard M, Andresen BS, Kristensen P, Frøhlich R, Knudsen BR. Topoisomerase 1 inhibits MYC promoter activity by inducing G-quadruplex formation. Nucleic Acids Res 2022; 50:6332-6342. [PMID: 35687110 PMCID: PMC9226537 DOI: 10.1093/nar/gkac482] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/28/2022] [Accepted: 06/07/2022] [Indexed: 11/23/2022] Open
Abstract
We have investigated the function of human topoisomerase 1 (TOP1) in regulation of G-quadruplex (G4) formation in the Pu27 region of the MYC P1 promoter. Pu27 is among the best characterized G4 forming sequences in the human genome and it is well known that promoter activity is inhibited upon G4 formation in this region. We found that TOP1 downregulation stimulated transcription from a promoter with wildtype Pu27 but not if the G4 motif in Pu27 was interrupted by mutation(s). The effect was not specific to the MYC promoter and similar results were obtained for the G4 forming promoter element WT21. The other major DNA topoisomerases with relaxation activity, topoisomerases 2α and β, on the other hand, did not affect G4 dependent promoter activity. The cellular studies were supported by in vitro investigations demonstrating a high affinity of TOP1 for wildtype Pu27 but not for mutant sequences unable to form G4. Moreover, TOP1 was able to induce G4 formation in Pu27 inserted in double stranded plasmid DNA in vitro. This is the first time TOP1 has been demonstrated capable of inducing G4 formation in double stranded DNA and of influencing G4 formation in cells.
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Affiliation(s)
- Josephine Geertsen Keller
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark.,Department of Clinical Medicine, Aarhus University, 8000 Aarhus C, Denmark
| | | | | | - Noriko Y Hansen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | - Jens Uldum Erlandsen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | - Cinzia Tesauro
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Anne Bech Andersen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Lise Lolle Holm
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark.,Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Magnus Stougaard
- Department of Clinical Medicine, Aarhus University, 8000 Aarhus C, Denmark.,Department of Pathology, Aarhus University Hospital, 8000 Aarhus C, Denmark
| | - Brage Storstein Andresen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense M, Denmark.,Villum Center for Bioanalytical Sciences, University of Southern Denmark, 5230 Odense M, Denmark
| | - Peter Kristensen
- Faculty of Engineering and Science, Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg, Denmark
| | - Rikke Frøhlich
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | - Birgitta R Knudsen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
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5
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Camarillo R, Jimeno S, Huertas P. The Effect of Atypical Nucleic Acids Structures in DNA Double Strand Break Repair: A Tale of R-loops and G-Quadruplexes. Front Genet 2021; 12:742434. [PMID: 34691154 PMCID: PMC8531813 DOI: 10.3389/fgene.2021.742434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/28/2021] [Indexed: 01/08/2023] Open
Abstract
The fine tuning of the DNA double strand break repair pathway choice relies on different regulatory layers that respond to environmental and local cues. Among them, the presence of non-canonical nucleic acids structures seems to create challenges for the repair of nearby DNA double strand breaks. In this review, we focus on the recently published effects of G-quadruplexes and R-loops on DNA end resection and homologous recombination. Finally, we hypothesized a connection between those two atypical DNA structures in inhibiting the DNA end resection step of HR.
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Affiliation(s)
- Rosa Camarillo
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.,Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
| | - Sonia Jimeno
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.,Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
| | - Pablo Huertas
- Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.,Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Sevilla, Spain
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6
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The Functional Consequences of Eukaryotic Topoisomerase 1 Interaction with G-Quadruplex DNA. Genes (Basel) 2020; 11:genes11020193. [PMID: 32059547 PMCID: PMC7073998 DOI: 10.3390/genes11020193] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/07/2020] [Accepted: 02/09/2020] [Indexed: 12/22/2022] Open
Abstract
Topoisomerase I in eukaryotic cells is an important regulator of DNA topology. Its catalytic function is to remove positive or negative superhelical tension by binding to duplex DNA, creating a reversible single-strand break, and finally religating the broken strand. Proper maintenance of DNA topological homeostasis, in turn, is critically important in the regulation of replication, transcription, DNA repair, and other processes of DNA metabolism. One of the cellular processes regulated by the DNA topology and thus by Topoisomerase I is the formation of non-canonical DNA structures. Non-canonical or non-B DNA structures, including the four-stranded G-quadruplex or G4 DNA, are potentially pathological in that they interfere with replication or transcription, forming hotspots of genome instability. In this review, we first describe the role of Topoisomerase I in reducing the formation of non-canonical nucleic acid structures in the genome. We further discuss the interesting recent discovery that Top1 and Top1 mutants bind to G4 DNA structures in vivo and in vitro and speculate on the possible consequences of these interactions.
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7
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Kim N. The Interplay between G-quadruplex and Transcription. Curr Med Chem 2019; 26:2898-2917. [PMID: 29284393 PMCID: PMC6026074 DOI: 10.2174/0929867325666171229132619] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/22/2017] [Accepted: 12/21/2017] [Indexed: 12/25/2022]
Abstract
G4 DNA is a non-canonical DNA structure consisting of a stacked array of Gquartets held together by base pairing between guanine bases. The formation of G4 DNA requires a cluster of guanine-runs within a strand of DNA. Even though the chemistry of this remarkable DNA structure has been under investigation for decades, evidence supporting the biological relevance of G4 DNA has only begun to emerge and point to very important and conserved biological functions. This review will specifically focus on the interplay between transcription and G4 DNA and discuss two alternative but interconnected perspectives. The first part of the review will describe the evidence substantiating the intriguing idea that a shift in DNA structural conformation could be another layer of non-genetic or epigenetic regulator of gene expression and thereby an important determinant of cell fate. The second part will describe the recent genetic studies showing that those genomic loci containing G4 DNA-forming guanine-rich sequences are potential hotspots of genome instability and that the level and orientation of transcription is critical in the materialization of genome instability associated with these sequences.
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Affiliation(s)
- Nayun Kim
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
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8
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Abstract
Topoisomerase I (Top1) resolves torsional stress that accumulates during transcription, replication and chromatin remodeling by introducing a transient single-strand break in DNA. The cleavage activity of Top1 has opposing roles, either promoting or destabilizing genome integrity depending on the context. Resolution of transcription-associated negative supercoils, for example, prevents pairing of the nascent RNA with the DNA template (R-loops) as well as DNA secondary structure formation. Reduced Top1 levels thus enhance CAG repeat contraction, somatic hypermutation, and class switch recombination. Actively transcribed ribosomal DNA is also destabilized in the absence of Top1, reflecting the importance of Top1 in ensuring efficient transcription. In terms of promoting genome instability, an aborted Top1 catalytic cycle stimulates deletions at short tandem repeats and the enzyme's transesterification activity supports illegitimate recombination. Finally, Top1 incision at ribonucleotides embedded in DNA generates deletions in tandem repeats, and induces gross chromosomal rearrangements and mitotic recombination.
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Affiliation(s)
- Jang-Eun Cho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, CARL 384, Durham, NC, 27710, USA
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, 213 Research Drive, CARL 384, Durham, NC, 27710, USA.
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9
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Multi-targeted effects of G4-aptamers and their antiproliferative activity against cancer cells. Biochimie 2017; 145:163-173. [PMID: 29208488 DOI: 10.1016/j.biochi.2017.11.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/30/2017] [Indexed: 12/20/2022]
Abstract
We selected and investigated nine G-quadruplex (G4)-forming aptamers originally designed against different proteins involved in the regulation of cellular proliferation (STAT3, nucleolin, TOP1, SP1, VEGF, and SHP-2) and considered to be potential anticancer agents. We showed that under physiological conditions all the aptamers form stable G4s of different topology. G4 aptamers designed against STAT3, nucleolin and SP1 inhibit STAT3 transcriptional activity in human breast adenocarcinoma MCF-7 cells, and all the studied aptamers inhibit TOP1-mediated relaxation of supercoiled plasmid DNA. STAT3 inhibition by G4 aptamer designed against SP1 protein provides a new explanation for the SP1 and STAT3 crosstalk described recently. We found some correlation between G4-mediated inhibition of the DNA replication and TOP1 activity. Four G4 aptamers from our dataset that appeared to be the strongest TOP1 inhibitors most efficiently decreased de novo DNA synthesis, by up to 79-87%. Seven G4 aptamers demonstrated significantly higher antiproliferative activity on human breast adenocarcinoma MCF-7 cells than on immortalized mammary epithelial MCF-10A cells. Pleiotropic properties of G4 aptamers and their high specificity against cancer cells observed for the majority of the studied G4 aptamers allowed us to present them as promising candidates for multi-targeted cancer therapy.
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10
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Abstract
Topoisomerases manage the torsional stress associated with the separation of DNA strands during transcription and DNA replication. Eukaryotic Topoisomerase I (Top1) is a Type IB enzyme that nicks and rejoins only one strand of duplex DNA, and it is especially important during transcription. By resolving transcription-associated torsional stress, Top1 reduces the accumulation of genome-destabilizing R-loops and non-B DNA structures. The DNA nicking activity of Top1, however, can also initiate genome instability in the form of illegitimate recombination, homologous recombination and mutagenesis. In this review, we focus on the diverse, and often opposing, roles of Top1 in regulating eukaryotic genome stability.
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11
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Dolinnaya NG, Ogloblina AM, Yakubovskaya MG. Structure, Properties, and Biological Relevance of the DNA and RNA G-Quadruplexes: Overview 50 Years after Their Discovery. BIOCHEMISTRY (MOSCOW) 2017; 81:1602-1649. [PMID: 28260487 PMCID: PMC7087716 DOI: 10.1134/s0006297916130034] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
G-quadruplexes (G4s), which are known to have important roles in regulation of key biological processes in both normal and pathological cells, are the most actively studied non-canonical structures of nucleic acids. In this review, we summarize the results of studies published in recent years that change significantly scientific views on various aspects of our understanding of quadruplexes. Modern notions on the polymorphism of DNA quadruplexes, on factors affecting thermodynamics and kinetics of G4 folding–unfolding, on structural organization of multiquadruplex systems, and on conformational features of RNA G4s and hybrid DNA–RNA G4s are discussed. Here we report the data on location of G4 sequence motifs in the genomes of eukaryotes, bacteria, and viruses, characterize G4-specific small-molecule ligands and proteins, as well as the mechanisms of their interactions with quadruplexes. New information on the structure and stability of G4s in telomeric DNA and oncogene promoters is discussed as well as proof being provided on the occurrence of G-quadruplexes in cells. Prominence is given to novel experimental techniques (single molecule manipulations, optical and magnetic tweezers, original chemical approaches, G4 detection in situ, in-cell NMR spectroscopy) that facilitate breakthroughs in the investigation of the structure and functions of G-quadruplexes.
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Affiliation(s)
- N G Dolinnaya
- Lomonosov Moscow State University, Department of Chemistry, Moscow, 119991, Russia.
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12
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Yadav P, Owiti N, Kim N. The role of topoisomerase I in suppressing genome instability associated with a highly transcribed guanine-rich sequence is not restricted to preventing RNA:DNA hybrid accumulation. Nucleic Acids Res 2015; 44:718-29. [PMID: 26527723 PMCID: PMC4737143 DOI: 10.1093/nar/gkv1152] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/19/2015] [Indexed: 11/21/2022] Open
Abstract
Highly transcribed guanine-run containing sequences, in Saccharomyces cerevisiae, become unstable when topoisomerase I (Top1) is disrupted. Topological changes, such as the formation of extended RNA:DNA hybrids or R-loops or non-canonical DNA structures including G-quadruplexes has been proposed as the major underlying cause of the transcription-linked genome instability. Here, we report that R-loop accumulation at a guanine-rich sequence, which is capable of assembling into the four-stranded G4 DNA structure, is dependent on the level and the orientation of transcription. In the absence of Top1 or RNase Hs, R-loops accumulated to substantially higher extent when guanine-runs were located on the non-transcribed strand. This coincides with the orientation where higher genome instability was observed. However, we further report that there are significant differences between the disruption of RNase Hs and Top1 in regards to the orientation-specific elevation in genome instability at the guanine-rich sequence. Additionally, genome instability in Top1-deficient yeasts is not completely suppressed by removal of negative supercoils and further aggravated by expression of mutant Top1. Together, our data provide a strong support for a function of Top1 in suppressing genome instability at the guanine-run containing sequence that goes beyond preventing the transcription-associated RNA:DNA hybrid formation.
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Affiliation(s)
- Puja Yadav
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Norah Owiti
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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13
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Ogloblina AM, Bannikova VA, Khristich AN, Oretskaya TS, Yakubovskaya MG, Dolinnaya NG. Parallel G-quadruplexes formed by guanine-rich microsatellite repeats inhibit human topoisomerase I. BIOCHEMISTRY (MOSCOW) 2015; 80:1026-38. [DOI: 10.1134/s0006297915080088] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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14
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Yadav P, Harcy V, Argueso JL, Dominska M, Jinks-Robertson S, Kim N. Topoisomerase I plays a critical role in suppressing genome instability at a highly transcribed G-quadruplex-forming sequence. PLoS Genet 2014; 10:e1004839. [PMID: 25473964 PMCID: PMC4256205 DOI: 10.1371/journal.pgen.1004839] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/20/2014] [Indexed: 11/18/2022] Open
Abstract
G-quadruplex or G4 DNA is a non-B secondary DNA structure that comprises a stacked array of guanine-quartets. Cellular processes such as transcription and replication can be hindered by unresolved DNA secondary structures potentially endangering genome maintenance. As G4-forming sequences are highly frequent throughout eukaryotic genomes, it is important to define what factors contribute to a G4 motif becoming a hotspot of genome instability. Using a genetic assay in Saccharomyces cerevisiae, we previously demonstrated that a potential G4-forming sequence derived from a guanine-run containing immunoglobulin switch Mu (Sμ) region becomes highly unstable when actively transcribed. Here we describe assays designed to survey spontaneous genome rearrangements initiated at the Sμ sequence in the context of large genomic areas. We demonstrate that, in the absence of Top1, a G4 DNA-forming sequence becomes a strong hotspot of gross chromosomal rearrangements and loss of heterozygosity associated with mitotic recombination within the ∼20 kb or ∼100 kb regions of yeast chromosome V or III, respectively. Transcription confers a critical strand bias since genome rearrangements at the G4-forming Sμ are elevated only when the guanine-runs are located on the non-transcribed strand. The direction of replication and transcription, when in a head-on orientation, further contribute to the elevated genome instability at a potential G4 DNA-forming sequence. The implications of our identification of Top1 as a critical factor in suppression of instability associated with potential G4 DNA-forming sequences are discussed. Genome instability is not evenly distributed, but rather is highly elevated at certain genomic loci containing DNA sequences that can fold into non-canonical secondary structures. The four-stranded G-quadruplex or G4 DNA is one such DNA structure capable of instigating transcription and/or replication obstruction and subsequent genome instability. In this study, we used a reporter system to quantitatively measure the level of genome instability occurring at a G4 DNA motif integrated into the yeast genome. We showed that the disruption of Topoisomerase I function significantly elevated various types of genome instability at the highly transcribed G4 motif generating loss of heterozygosity and copy number alterations (deletions and duplications), both of which are frequently observed in cancer genomes.
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Affiliation(s)
- Puja Yadav
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Victoria Harcy
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Juan Lucas Argueso
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Margaret Dominska
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- * E-mail:
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15
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Hoshyar R, Bathaie SZ, Kyani A, Mousavi MF. Is there any interaction between telomeric DNA structures, G-quadruplex and I-motif, with saffron active metabolites? NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2014; 31:801-12. [PMID: 23145950 DOI: 10.1080/15257770.2012.730164] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Telomeric DNA contains some unique secondary structures, such as G-quadruplex and I-motif. These structures may be stabilized or changed by binding to specific proteins or small molecules. Herein, we report the in vitro effect of crocin, crocetin, picrocrocin, and safranal on these structures. Circular dichroism (CD) data indicate that crocetin has higher affinity for these structures. Safranal and crocin induce little change in the I-motif and G-quadruplex, respectively. The molecular docking confirms the experimental data and indicates the minor groove binding of ligands with G-quadruplex. The possibility for application of these ligands as sequence-specific drugs should be further investigated.
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Affiliation(s)
- Reyhane Hoshyar
- Department of Clinical Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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