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Han ZQ, Wen LN. Application of G-quadruplex targets in gastrointestinal cancers: Advancements, challenges and prospects. World J Gastrointest Oncol 2023; 15:1149-1173. [PMID: 37546556 PMCID: PMC10401460 DOI: 10.4251/wjgo.v15.i7.1149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 04/11/2023] [Accepted: 05/08/2023] [Indexed: 07/12/2023] Open
Abstract
Genomic instability and inflammation are considered to be two enabling characteristics that support cancer development and progression. G-quadruplex structure is a key element that contributes to genomic instability and inflammation. G-quadruplexes were once regarded as simply an obstacle that can block the transcription of oncogenes. A ligand targeting G-quadruplexes was found to have anticancer activity, making G-quadruplexes potential anticancer targets. However, further investigation has revealed that G-quadruplexes are widely distributed throughout the human genome and have many functions, such as regulating DNA replication, DNA repair, transcription, translation, epigenetics, and inflammatory response. G-quadruplexes play double regulatory roles in transcription and translation. In this review, we focus on G-quadruplexes as novel targets for the treatment of gastrointestinal cancers. We summarize the application basis of G-quadruplexes in gastrointestinal cancers, including their distribution sites, structural characteristics, and physiological functions. We describe the current status of applications for the treatment of esophageal cancer, pancreatic cancer, hepatocellular carcinoma, gastric cancer, colorectal cancer, and gastrointestinal stromal tumors, as well as the associated challenges. Finally, we review the prospective clinical applications of G-quadruplex targets, providing references for targeted treatment strategies in gastrointestinal cancers.
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Affiliation(s)
- Zong-Qiang Han
- Department of Laboratory Medicine, Beijing Xiaotangshan Hospital, Beijing 102211, China
| | - Li-Na Wen
- Department of Clinical Nutrition, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, 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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Pavlova AV, Dolinnaya NG, Zvereva MI, Kubareva EA, Monakhova MV. New DNA Plasmid Model for Studying DNA Mismatch Repair Response to the G4 Structure. Int J Mol Sci 2023; 24:ijms24021061. [PMID: 36674575 PMCID: PMC9863064 DOI: 10.3390/ijms24021061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 12/27/2022] [Accepted: 12/31/2022] [Indexed: 01/08/2023] Open
Abstract
G-quadruplexes (G4s), the most widely studied alternative DNA structures, are implicated in the regulation of the key cellular processes. In recent years, their involvement in DNA repair machinery has become the subject of intense research. Here, we evaluated the effect of G4 on the prokaryotic DNA mismatch repair (MMR) pathway from two bacterial sources with different mismatch repair mechanisms. The G4 folding, which competes with the maintenance of double-stranded DNA, is known to be controlled by numerous opposing factors. To overcome the kinetic barrier of G4 formation, we stabilized a parallel G4 formed by the d(GGGT)4 sequence in a DNA plasmid lacking a fragment complementary to the G4 motif. Unlike commonly used isolated G4 structures, our plasmid with an embedded stable G4 structure contained elements, such as a MutH cleavage site, required to initiate the repair process. G4 formation in the designed construct was confirmed by Taq polymerase stop assay and dimethyl sulfate probing. The G4-carrying plasmid, together with control ones (lacking a looped area or containing unstructured d(GT)8 insert instead of the G4 motif), were used as new type models to answer the question of whether G4 formation interferes with DNA cleavage as a basic function of MMR.
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Affiliation(s)
- Anzhela V. Pavlova
- Department of Chemistry, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
| | - Nina G. Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
| | - Maria I. Zvereva
- Department of Chemistry, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
| | - Elena A. Kubareva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
- Correspondence: ; Tel.: +7-(495)-939-54-11
| | - Mayya V. Monakhova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskye Gory 1, Moscow 119991, Russia
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4
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Li D, Chen X, Yan R, Jiang Z, Zhou B, Lv B. G-quadruplex-containing oligodeoxynucleotides as DNA topoisomerase I inhibitors. Int J Biol Macromol 2022; 223:281-289. [PMID: 36356864 DOI: 10.1016/j.ijbiomac.2022.11.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/24/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Abstract
DNA topoisomerase I was found to be highly abundant in fast-proliferating tumor cells and is a potential target for anticancer therapy. A series of G-quadruplex-containing oligodeoxynucleotides (ODNs) were designed and used as inhibitors of DNA topoisomerase I. It was demonstrated that ODNs with G-quadruplexes can efficiently inhibit the supercoiled DNA relaxation reaction catalyzed by DNA topoisomerase I. Compared with the other conformations, the parallel propeller-type G-quadruplex was the most efficient DNA topoisomerase I inhibitor. Further studies revealed that integrating G-quadruplexes with duplexes to form quadruplex-duplex hybrids could significantly improve the inhibition efficiency. In addition, a circular ODN that consists of a G-quadruplex motif and DNA topoisomerase I binding site was synthesized and used as a DNA topoisomerase I inhibitor. The results showed that the particularly designed circular ODN displayed high inhibitory efficiency on the activity of DNA topoisomerase I with an IC50 value of 54.8 nM. Moreover, the circular ODN exhibited excellent thermal stability and nuclease resistance. Considering the low cytotoxicity of DNA-based biopharmaceuticals, the design strategy and results reported in this study may shed new light on nucleic acid-based DNA topoisomerase I inhibitor construction for potential anticancer drugs.
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Affiliation(s)
- Dawei Li
- Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of State Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China.
| | - Xiyu Chen
- Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of State Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
| | - Rumeng Yan
- Jiangsu Key Laboratory for Biofunctional Molecules, College of Life Science and Chemistry, Jiangsu Second Normal University, Nanjing 210013, China
| | - Zeshan Jiang
- Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of State Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
| | - Bing Zhou
- Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of State Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
| | - Bei Lv
- Jiangsu Key Laboratory for Biofunctional Molecules, College of Life Science and Chemistry, Jiangsu Second Normal University, Nanjing 210013, China.
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5
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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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6
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Wu Z, Gong H, Zhou Z, Jiang T, Lin Z, Li J, Xiao S, Yang B, Huang L. Mapping short tandem repeats for liver gene expression traits helps prioritize potential causal variants for complex traits in pigs. J Anim Sci Biotechnol 2022; 13:8. [PMID: 35034641 PMCID: PMC8762894 DOI: 10.1186/s40104-021-00658-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 11/25/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Short tandem repeats (STRs) were recently found to have significant impacts on gene expression and diseases in humans, but their roles on gene expression and complex traits in pigs remain unexplored. This study investigates the effects of STRs on gene expression in liver tissues based on the whole-genome sequences and RNA-Seq data of a discovery cohort of 260 F6 individuals and a validation population of 296 F7 individuals from a heterogeneous population generated from crosses among eight pig breeds. RESULTS We identified 5203 and 5868 significantly expression STRs (eSTRs, FDR < 1%) in the F6 and F7 populations, respectively, most of which could be reciprocally validated (π1 = 0.92). The eSTRs explained 27.5% of the cis-heritability of gene expression traits on average. We further identified 235 and 298 fine-mapped STRs through the Bayesian fine-mapping approach in the F6 and F7 pigs, respectively, which were significantly enriched in intron, ATAC peak, compartment A and H3K4me3 regions. We identified 20 fine-mapped STRs located in 100 kb windows upstream and downstream of published complex trait-associated SNPs, which colocalized with epigenetic markers such as H3K27ac and ATAC peaks. These included eSTR of the CLPB, PGLS, PSMD6 and DHDH genes, which are linked with genome-wide association study (GWAS) SNPs for blood-related traits, leg conformation, growth-related traits, and meat quality traits, respectively. CONCLUSIONS This study provides insights into the effects of STRs on gene expression traits. The identified eSTRs are valuable resources for prioritizing causal STRs for complex traits in pigs.
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Affiliation(s)
- Zhongzi Wu
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Huanfa Gong
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Zhimin Zhou
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Tao Jiang
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Ziqi Lin
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Jing Li
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Shijun Xiao
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China
| | - Bin Yang
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China.
| | - Lusheng Huang
- State Key Laboratory for Pig Genetic Improvement and Production Technology, Jiangxi Agricultural University, Nanchang, China.
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7
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Beyond G-Quadruplexes-The Effect of Junction with Additional Structural Motifs on Aptamers Properties. Int J Mol Sci 2021; 22:ijms22189948. [PMID: 34576112 PMCID: PMC8466185 DOI: 10.3390/ijms22189948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 12/02/2022] Open
Abstract
G-quadruplexes constitute an important type of nucleic acid structure, which can be found in living cells and applied by cell machinery as pivotal regulatory elements. Importantly, robust development of SELEX technology and modern, nucleic acid-based therapeutic strategies targeted towards various molecules have also revealed a large group of potent aptamers whose structures are grounded in G-quadruplexes. In this review, we analyze further extension of tetraplexes by additional structural elements and investigate whether G-quadruplex junctions with duplex, hairpin, triplex, or second G-quadruplex motifs are favorable for aptamers stability and biological activity. Furthermore, we indicate the specific and pivotal role of the G-quadruplex domain and the additional structural elements in interactions with target molecules. Finally, we consider the potency of G-quadruplex junctions in future applications and indicate the emerging research area that is still waiting for development to obtain highly specific and effective nucleic acid-based molecular tools.
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8
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Real-Hohn A, Blaas D. Rhinovirus Inhibitors: Including a New Target, the Viral RNA. Viruses 2021; 13:1784. [PMID: 34578365 PMCID: PMC8473194 DOI: 10.3390/v13091784] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/21/2021] [Accepted: 09/03/2021] [Indexed: 12/18/2022] Open
Abstract
Rhinoviruses (RVs) are the main cause of recurrent infections with rather mild symptoms characteristic of the common cold. Nevertheless, RVs give rise to enormous numbers of absences from work and school and may become life-threatening in particular settings. Vaccination is jeopardised by the large number of serotypes eliciting only poorly cross-neutralising antibodies. Conversely, antivirals developed over the years failed FDA approval because of a low efficacy and/or side effects. RV species A, B, and C are now included in the fifteen species of the genus Enteroviruses based upon the high similarity of their genome sequences. As a result of their comparably low pathogenicity, RVs have become a handy model for other, more dangerous members of this genus, e.g., poliovirus and enterovirus 71. We provide a short overview of viral proteins that are considered potential drug targets and their corresponding drug candidates. We briefly mention more recently identified cellular enzymes whose inhibition impacts on RVs and comment novel approaches to interfere with infection via aggregation, virus trapping, or preventing viral access to the cell receptor. Finally, we devote a large part of this article to adding the viral RNA genome to the list of potential drug targets by dwelling on its structure, folding, and the still debated way of its exit from the capsid. Finally, we discuss the recent finding that G-quadruplex stabilising compounds impact on RNA egress possibly via obfuscating the unravelling of stable secondary structural elements.
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Affiliation(s)
- Antonio Real-Hohn
- Center for Medical Biochemistry, Vienna Biocenter, Max Perutz Laboratories, Medical University of Vienna, Dr. Bohr Gasse 9/3, A-1030 Vienna, Austria
| | - Dieter Blaas
- Center for Medical Biochemistry, Vienna Biocenter, Max Perutz Laboratories, Medical University of Vienna, Dr. Bohr Gasse 9/3, A-1030 Vienna, Austria
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9
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Gharesouran J, Hosseinzadeh H, Ghafouri-Fard S, Taheri M, Rezazadeh M. STRs: Ancient Architectures of the Genome beyond the Sequence. J Mol Neurosci 2021; 71:2441-2455. [PMID: 34056692 DOI: 10.1007/s12031-021-01850-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/22/2021] [Indexed: 01/24/2023]
Abstract
Short tandem repeats (STRs) are commonly defined as short runs of repetitive nucleotides, consisting of tandemly repeating 2-6- bp motif units, which are ubiquitously distributed throughout genomes. Functional STRs are polymorphic in the population, and their variations influence gene expression, which subsequently may result in pathogenic phenotypes. To understand STR phenotypic effects and their functional roles, we describe four different mutational mechanisms including the unequal crossing-over model, gene conversion, retrotransposition mechanism and replication slippage. Due to the multi-allelic nature, small length, abundance, high variability, codominant inheritance, nearly neutral evolution, extensive genome coverage and simple assaying of STRs, these markers are widely used in various types of biological research, including population genetics studies, genome mapping, molecular epidemiology, paternity analysis and gene flow studies. In this review, we focus on the current knowledge regarding STR genomic distribution, function, mutation and applications.
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Affiliation(s)
- Jalal Gharesouran
- Molecular Genetics Division, GMG center, Tabriz, Iran.,Division of Medical Genetics, Tabriz Childrens Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Hassan Hosseinzadeh
- Molecular Genetics Division, GMG center, Tabriz, Iran.,Division of Medical Genetics, Tabriz Childrens Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Soudeh Ghafouri-Fard
- Department of Medical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Taheri
- Skull Base Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Maryam Rezazadeh
- Division of Medical Genetics, Tabriz Childrens Hospital, Tabriz University of Medical Sciences, Tabriz, Iran. .,Department of Medical Genetics, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
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10
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Responses of DNA Mismatch Repair Proteins to a Stable G-Quadruplex Embedded into a DNA Duplex Structure. Int J Mol Sci 2020; 21:ijms21228773. [PMID: 33233554 PMCID: PMC7699706 DOI: 10.3390/ijms21228773] [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: 10/26/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 12/26/2022] Open
Abstract
DNA mismatch repair (MMR) plays a crucial role in the maintenance of genomic stability. The main MMR protein, MutS, was recently shown to recognize the G-quadruplex (G4) DNA structures, which, along with regulatory functions, have a negative impact on genome integrity. Here, we studied the effect of G4 on the DNA-binding activity of MutS from Rhodobacter sphaeroides (methyl-independent MMR) in comparison with MutS from Escherichia coli (methyl-directed MMR) and evaluated the influence of a G4 on the functioning of other proteins involved in the initial steps of MMR. For this purpose, a new DNA construct was designed containing a biologically relevant intramolecular stable G4 structure flanked by double-stranded regions with the set of DNA sites required for MMR initiation. The secondary structure of this model was examined using NMR spectroscopy, chemical probing, fluorescent indicators, circular dichroism, and UV spectroscopy. The results unambiguously showed that the d(GGGT)4 motif, when embedded in a double-stranded context, adopts a G4 structure of a parallel topology. Despite strong binding affinities of MutS and MutL for a G4, the latter is not recognized by E. coli MMR as a signal for repair, but does not prevent MMR processing when a G4 and G/T mismatch are in close proximity.
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11
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Ogloblina AM, Iaccarino N, Capasso D, Di Gaetano S, Garzarella EU, Dolinnaya NG, Yakubovskaya MG, Pagano B, Amato J, Randazzo A. Toward G-Quadruplex-Based Anticancer Agents: Biophysical and Biological Studies of Novel AS1411 Derivatives. Int J Mol Sci 2020; 21:E7781. [PMID: 33096752 PMCID: PMC7590035 DOI: 10.3390/ijms21207781] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 12/16/2022] Open
Abstract
Certain G-quadruplex forming guanine-rich oligonucleotides (GROs), including AS1411, are endowed with cancer-selective antiproliferative activity. They are known to bind to nucleolin protein, resulting in the inhibition of nucleolin-mediated phenomena. However, multiple nucleolin-independent biological effects of GROs have also been reported, allowing them to be considered promising candidates for multi-targeted cancer therapy. Herein, with the aim of optimizing AS1411 structural features to find GROs with improved anticancer properties, we have studied a small library of AS1411 derivatives differing in the sequence length and base composition. The AS1411 derivatives were characterized by using circular dichroism and nuclear magnetic resonance spectroscopies and then investigated for their enzymatic resistance in serum and nuclear extract, as well as for their ability to bind nucleolin, inhibit topoisomerase I, and affect the viability of MCF-7 human breast adenocarcinoma cells. All derivatives showed higher thermal stability and inhibitory effect against topoisomerase I than AS1411. In addition, most of them showed an improved antiproliferative activity on MCF-7 cells compared to AS1411 despite a weaker binding to nucleolin. Our results support the hypothesis that the antiproliferative properties of GROs are due to multi-targeted effects.
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Affiliation(s)
- Anna M. Ogloblina
- N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health, 115478 Moscow, Russia; (A.M.O.); (M.G.Y.)
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Nunzia Iaccarino
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Domenica Capasso
- Center for Life Sciences and Technologies (CESTEV), University of Naples Federico II, Via A. De Amicis 95, 80145 Naples, Italy;
| | - Sonia Di Gaetano
- Institute of Biostructures and Bioimaging, National Research Council, Via Mezzocannone 16, 80134 Naples, Italy;
| | - Emanuele U. Garzarella
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Nina G. Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia;
| | - Marianna G. Yakubovskaya
- N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health, 115478 Moscow, Russia; (A.M.O.); (M.G.Y.)
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Via D. Montesano 49, 80131 Naples, Italy; (N.I.); (E.U.G.); (A.R.)
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12
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Khristich AN, Mirkin SM. On the wrong DNA track: Molecular mechanisms of repeat-mediated genome instability. J Biol Chem 2020; 295:4134-4170. [PMID: 32060097 PMCID: PMC7105313 DOI: 10.1074/jbc.rev119.007678] [Citation(s) in RCA: 141] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Expansions of simple tandem repeats are responsible for almost 50 human diseases, the majority of which are severe, degenerative, and not currently treatable or preventable. In this review, we first describe the molecular mechanisms of repeat-induced toxicity, which is the connecting link between repeat expansions and pathology. We then survey alternative DNA structures that are formed by expandable repeats and review the evidence that formation of these structures is at the core of repeat instability. Next, we describe the consequences of the presence of long structure-forming repeats at the molecular level: somatic and intergenerational instability, fragility, and repeat-induced mutagenesis. We discuss the reasons for gender bias in intergenerational repeat instability and the tissue specificity of somatic repeat instability. We also review the known pathways in which DNA replication, transcription, DNA repair, and chromatin state interact and thereby promote repeat instability. We then discuss possible reasons for the persistence of disease-causing DNA repeats in the genome. We describe evidence suggesting that these repeats are a payoff for the advantages of having abundant simple-sequence repeats for eukaryotic genome function and evolvability. Finally, we discuss two unresolved fundamental questions: (i) why does repeat behavior differ between model systems and human pedigrees, and (ii) can we use current knowledge on repeat instability mechanisms to cure repeat expansion diseases?
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Affiliation(s)
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, Massachusetts 02155.
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13
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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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14
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Lowran K, Campbell L, Popp P, Wu CG. Assembly of a G-Quadruplex Repair Complex by the FANCJ DNA Helicase and the REV1 Polymerase. Genes (Basel) 2019; 11:E5. [PMID: 31861576 PMCID: PMC7017153 DOI: 10.3390/genes11010005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 12/17/2019] [Indexed: 12/14/2022] Open
Abstract
The FANCJ helicase unfolds G-quadruplexes (G4s) in human cells to support DNA replication. This action is coupled to the recruitment of REV1 polymerase to synthesize DNA across from a guanine template. The precise mechanisms of these reactions remain unclear. While FANCJ binds to G4s with an AKKQ motif, it is not known whether this site recognizes damaged G4 structures. FANCJ also has a PIP-like (PCNA Interacting Protein) region that may recruit REV1 to G4s either directly or through interactions mediated by PCNA protein. In this work, we measured the affinities of a FANCJ AKKQ peptide for G4s formed by (TTAGGG)4 and (GGGT)4 using fluorescence spectroscopy and biolayer interferometry (BLI). The effects of 8-oxoguanine (8oxoG) on these interactions were tested at different positions. BLI assays were then performed with a FANCJ PIP to examine its recruitment of REV1 and PCNA. FANCJ AKKQ bound tightly to a TTA loop and was sequestered away from the 8oxoG. Reducing the loop length between guanine tetrads increased the affinity of the peptide for 8oxoG4s. FANCJ PIP targeted both REV1 and PCNA but favored interactions with the REV1 polymerase. The impact of these results on the remodeling of damaged G4 DNA is discussed herein.
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Affiliation(s)
- Kaitlin Lowran
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA; (K.L.); (L.C.)
| | - Laura Campbell
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA; (K.L.); (L.C.)
| | - Phillip Popp
- Case Western Reserve University, Cleveland, OH 44106, USA;
| | - Colin G. Wu
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA; (K.L.); (L.C.)
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15
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Viryasova GM, Dolinnaya NG, Golenkina EA, Gaponova TV, Viryasov MB, Romanova YM, Sud'ina GF. G-quadruplex-forming oligodeoxyribonucleotides activate leukotriene synthesis in human neutrophils. J Biomol Struct Dyn 2019; 37:3649-3659. [PMID: 30238827 DOI: 10.1080/07391102.2018.1523748] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Human polymorphonuclear leukocytes (PMNLs, neutrophils) play a major role in the immune response to bacterial and fungal infections and eliminate pathogens through phagocytosis. During phagocytosis of microorganisms, the 5-lipoxygenase (5-LOX) pathway is activated resulting in generation of leukotrienes, which mediate host defense. In this study, a library of oligodeoxyribonucleotides (ODNs) with varying numbers of human telomeric repeats (d(TTAGGG)n) and their analogues with phosphorothioate internucleotide linkages and single-nucleotide substitutions was designed. These ODNs with the potential to fold into G-quadruplex structures were studied from structural and functional perspectives. We showed that exogenous G-quadruplex-forming ODNs significantly enhanced 5-LOX metabolite formation in human neutrophils exposed to Salmonella Typhimurium bacteria. However, the activation of leukotriene synthesis was completely lost when G-quadruplex formation was prevented by substitution of guanosine with 7-deazaguanosine or adenosine residues at several positions. To our knowledge, this study is the first to demonstrate that G-quadruplex structures are potent regulators of 5-LOX product synthesis in human neutrophils in the presence of targets of phagocytosis. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Galina M Viryasova
- a Belozersky Institute of Physico-Chemical Biology , Lomonosov Moscow State University , Moscow , Russia
| | - Nina G Dolinnaya
- b Department of Chemistry , Lomonosov Moscow State University , Moscow , Russia
| | - Ekaterina A Golenkina
- a Belozersky Institute of Physico-Chemical Biology , Lomonosov Moscow State University , Moscow , Russia
| | - Tatjana V Gaponova
- c FGBU Hematology Research Centre , Russia Federation Ministry of Public Health , Moscow , Russia
| | - Mikhail B Viryasov
- b Department of Chemistry , Lomonosov Moscow State University , Moscow , Russia
| | - Yulia M Romanova
- d Gamaleya National Research Centre of Epidemiology and Microbiology , Moscow , Russia.,e Department of Unfectology and Virology, Sechenov First Moscow State Medical University , Moscow , Russia
| | - Galina F Sud'ina
- a Belozersky Institute of Physico-Chemical Biology , Lomonosov Moscow State University , Moscow , Russia
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16
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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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17
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Bagshaw AT. Functional Mechanisms of Microsatellite DNA in Eukaryotic Genomes. Genome Biol Evol 2017; 9:2428-2443. [PMID: 28957459 PMCID: PMC5622345 DOI: 10.1093/gbe/evx164] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2017] [Indexed: 02/06/2023] Open
Abstract
Microsatellite repeat DNA is best known for its length mutability, which is implicated in several neurological diseases and cancers, and often exploited as a genetic marker. Less well-known is the body of work exploring the widespread and surprisingly diverse functional roles of microsatellites. Recently, emerging evidence includes the finding that normal microsatellite polymorphism contributes substantially to the heritability of human gene expression on a genome-wide scale, calling attention to the task of elucidating the mechanisms involved. At present, these are underexplored, but several themes have emerged. I review evidence demonstrating roles for microsatellites in modulation of transcription factor binding, spacing between promoter elements, enhancers, cytosine methylation, alternative splicing, mRNA stability, selection of transcription start and termination sites, unusual structural conformations, nucleosome positioning and modification, higher order chromatin structure, noncoding RNA, and meiotic recombination hot spots.
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18
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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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19
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Rigo R, Palumbo M, Sissi C. G-quadruplexes in human promoters: A challenge for therapeutic applications. Biochim Biophys Acta Gen Subj 2016; 1861:1399-1413. [PMID: 28025083 DOI: 10.1016/j.bbagen.2016.12.024] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND G-rich sequences undergo unique structural equilibria to form G-quadruplexes (G4) both in vitro and in cell systems. Several pathologies emerged to be directly related to G4 occurrence at defined genomic portions. Additionally, G-rich sequences are significantly represented around transcription start sites (TSS) thus leading to the hypothesis of a gene regulatory function for G4. Thus, the tuning of G4 formation has been proposed as a new powerful tool to regulate gene expression to treat related pathologies. However, up-to date this approach did not provide any new really efficient treatment. SCOPE OF REVIEW Here, we summarize the most recent advances on the correlation between the structural features of G4 in human promoters and the role these systems physiologically exert. In particular we focus on the effect of G4 localization among cell compartments and along the promoters in correlation with protein interaction networks and epigenetic state. Finally the intrinsic structural features of G4 at promoters are discussed to unveil the contribution of different G4 structural modules in this complex architecture. MAJOR CONCLUSIONS It emerges that G4s play several roles in the intriguing and complex mechanism of gene expression, being able to produce opposite effects on the same target. This reflects the occurrence of a highly variegate network of several components working simultaneously. GENERAL SIGNIFICANCE The resulting picture is still fuzzy but some points of strength are definitely emerging, which prompts all of us to strengthen our efforts in view of a selective control of gene expression through G4 modulation. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Affiliation(s)
- Riccardo Rigo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Manlio Palumbo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Claudia Sissi
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy.
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20
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Wu CG, Spies M. G-quadruplex recognition and remodeling by the FANCJ helicase. Nucleic Acids Res 2016; 44:8742-8753. [PMID: 27342280 PMCID: PMC5062972 DOI: 10.1093/nar/gkw574] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/15/2016] [Indexed: 12/16/2022] Open
Abstract
Guanine rich nucleic acid sequences can form G-quadruplex (G4) structures that interfere with DNA replication, repair and RNA transcription. The human FANCJ helicase contributes to maintaining genomic integrity by promoting DNA replication through G4-forming DNA regions. Here, we combined single-molecule and ensemble biochemical analysis to show that FANCJ possesses a G4-specific recognition site. Through this interaction, FANCJ targets G4-containing DNA where its helicase and G4-binding activities enable repeated rounds of stepwise G4-unfolding and refolding. In contrast to other G4-remodeling enzymes, FANCJ partially stabilizes the G-quadruplex. This would preserve the substrate for the REV1 translesion DNA synthesis polymerase to incorporate cytosine across from a replication-stalling G-quadruplex. The residues responsible for G-quadruplex recognition also participate in interaction with MLH1 mismatch-repair protein, suggesting that the FANCJ activity supporting replication and its participation in DNA interstrand crosslink repair and/or heteroduplex rejection are mutually exclusive. Our findings not only describe the mechanism by which FANCJ recognizes G-quadruplexes and mediates their stepwise unfolding, but also explain how FANCJ chooses between supporting DNA repair versus promoting DNA replication through G-rich sequences.
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Affiliation(s)
- Colin G Wu
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Rd., 4-532 BSB, Iowa City, IA 52242, USA
| | - Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Rd., 4-532 BSB, Iowa City, IA 52242, USA
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