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Miranda A, Cucchiarini A, Esnault C, Andrau JC, Oliveira PA, Mergny JL, Cruz C. G-quadruplex forming motifs in the promoter region of the B-MYB proto-oncogene. Int J Biol Macromol 2024; 270:132244. [PMID: 38729459 DOI: 10.1016/j.ijbiomac.2024.132244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/10/2024] [Accepted: 05/07/2024] [Indexed: 05/12/2024]
Abstract
To combat cancer, a comprehensive understanding of the molecular mechanisms and behaviors involved in carcinogenesis is crucial, as tumorigenesis is a complex process influenced by various genetic events and disease hallmarks. The B-MYB gene encodes a transcription factor involved in cell cycle regulation, survival, and differentiation in normal cells. B-MYB can be transformed into an oncogene through mutations, and abnormal expression of B-MYB has been identified in various cancers, including lung cancer, and is associated with poor prognosis. Targeting this oncogene is a promising approach for anti-cancer drug design. B-MYB has been deemed undruggable in previous reports, necessitating the search for novel therapeutic options. In this study, we found that the B-MYB gene promoter contains several G/C rich motifs compatible with G-quadruplex (G4) formation. We investigated and validated the existence of G4 structures in the promoter region of B-MYB, first in vitro using a combination of bioinformatics, biophysical, and biochemical methods, then in cell with the recently developed G4access method.
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Affiliation(s)
- André Miranda
- CICS-UBI - Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal; Centre for Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Inov4Agro, University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, 5000-801 Vila Real, Portugal
| | - Anne Cucchiarini
- Laboratoire d'Optique et Biosciences, École Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Cyril Esnault
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR, 5535 Montpellier, France
| | - Jean-Christophe Andrau
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR, 5535 Montpellier, France
| | - Paula A Oliveira
- Centre for Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Inov4Agro, University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, 5000-801 Vila Real, Portugal
| | - Jean-Louis Mergny
- Laboratoire d'Optique et Biosciences, École Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91120 Palaiseau, France.
| | - Carla Cruz
- CICS-UBI - Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal; Departamento de Química, Universidade da Beira Interior, Rua Marquês de Ávila e Bolama, 6201-001 Covilhã, Portugal.
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2
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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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3
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Fukute J, Maki K, Adachi T. The nucleolar shell provides anchoring sites for DNA untwisting. Commun Biol 2024; 7:83. [PMID: 38263258 PMCID: PMC10805735 DOI: 10.1038/s42003-023-05750-w] [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: 08/18/2023] [Accepted: 12/28/2023] [Indexed: 01/25/2024] Open
Abstract
DNA underwinding (untwisting) is a crucial step in transcriptional activation. DNA underwinding occurs between the site where torque is generated by RNA polymerase (RNAP) and the site where the axial rotation of DNA is constrained. However, what constrains DNA axial rotation in the nucleus is yet unknown. Here, we show that the anchorage to the nuclear protein condensates constrains DNA axial rotation for DNA underwinding in the nucleolus. In situ super-resolution imaging of underwound DNA reveal that underwound DNA accumulates in the nucleolus, a nuclear condensate with a core-shell structure. Specifically, underwound DNA is distributed in the nucleolar core owing to RNA polymerase I (RNAPI) activities. Furthermore, underwound DNA in the core decreases when nucleolar shell components are prevented from binding to their recognition structure, G-quadruplex (G4). Taken together, these results suggest that the nucleolar shell provides anchoring sites that constrain DNA axial rotation for RNAPI-driven DNA underwinding in the core. Our findings will contribute to understanding how nuclear protein condensates make up constraints for the site-specific regulation of DNA underwinding and transcription.
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Affiliation(s)
- Jumpei Fukute
- Laboratory of Cellular and Molecular Biomechanics, Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto, Japan
- Laboratory of Biomechanics, Institute for Life and Medical Sciences, Kyoto University, Sakyo, Kyoto, Japan
| | - Koichiro Maki
- Laboratory of Cellular and Molecular Biomechanics, Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto, Japan.
- Laboratory of Biomechanics, Institute for Life and Medical Sciences, Kyoto University, Sakyo, Kyoto, Japan.
- Department of Micro Engineering, Graduate School of Engineering, Kyoto University, Sakyo, Kyoto, Japan.
- Department of Medicine and Medical Science, Graduate School of Medicine, Kyoto University, Sakyo, Kyoto, Japan.
| | - Taiji Adachi
- Laboratory of Cellular and Molecular Biomechanics, Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Sakyo, Kyoto, Japan
- Laboratory of Biomechanics, Institute for Life and Medical Sciences, Kyoto University, Sakyo, Kyoto, Japan
- Department of Micro Engineering, Graduate School of Engineering, Kyoto University, Sakyo, Kyoto, Japan
- Department of Medicine and Medical Science, Graduate School of Medicine, Kyoto University, Sakyo, Kyoto, Japan
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4
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Yan MP, Wee CE, Yen KP, Stevens A, Wai LK. G-quadruplex ligands as therapeutic agents against cancer, neurological disorders and viral infections. Future Med Chem 2023; 15:1987-2009. [PMID: 37933551 DOI: 10.4155/fmc-2023-0202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023] Open
Abstract
G-quadruplexes (G4s) within the human genome have undergone extensive molecular investigation, with a strong focus on telomeres, gene promoters and repetitive regulatory sequences. G4s play central roles in regulating essential biological processes, including telomere maintenance, replication, transcription and translation. Targeting these molecular processes with G4-binding ligands holds substantial therapeutic potential in anticancer treatments and has also shown promise in treating neurological, skeletal and muscular disorders. The presence of G4s in bacterial and viral genomes also suggests that G4-binding ligands could be a critical tool in fighting infections. This review provides an overview of the progress and applications of G4-binding ligands, their proposed mechanisms of action, challenges faced and prospects for their utilization in anticancer treatments, neurological disorders and antiviral activities.
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Affiliation(s)
- Mock Phooi Yan
- Centre for Drug & Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, 50300, Malaysia
| | - Chua Eng Wee
- Centre for Drug & Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, 50300, Malaysia
| | - Khor Poh Yen
- Faculty Pharmacy & Health Sciences, Universiti Kuala Lumpur, Royal College of Medicine Perak, 3, Jalan Greentown, Ipoh, Perak, 30450, Malaysia
| | - Aaron Stevens
- Department of Pathology & Molecular Medicine, University of Otago, Wellington, 6021, New Zealand
| | - Lam Kok Wai
- Centre for Drug & Herbal Development, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, 50300, Malaysia
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5
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Esnault C, Magat T, Zine El Aabidine A, Garcia-Oliver E, Cucchiarini A, Bouchouika S, Lleres D, Goerke L, Luo Y, Verga D, Lacroix L, Feil R, Spicuglia S, Mergny JL, Andrau JC. G4access identifies G-quadruplexes and their associations with open chromatin and imprinting control regions. Nat Genet 2023; 55:1359-1369. [PMID: 37400615 DOI: 10.1038/s41588-023-01437-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 05/31/2023] [Indexed: 07/05/2023]
Abstract
Metazoan promoters are enriched in secondary DNA structure-forming motifs, such as G-quadruplexes (G4s). Here we describe 'G4access', an approach to isolate and sequence G4s associated with open chromatin via nuclease digestion. G4access is antibody- and crosslinking-independent and enriches for computationally predicted G4s (pG4s), most of which are confirmed in vitro. Using G4access in human and mouse cells, we identify cell-type-specific G4 enrichment correlated with nucleosome exclusion and promoter transcription. G4access allows measurement of variations in G4 repertoire usage following G4 ligand treatment, HDAC and G4 helicases inhibitors. Applying G4access to cells from reciprocal hybrid mouse crosses suggests a role for G4s in the control of active imprinting regions. Consistently, we also observed that G4access peaks are unmethylated, while methylation at pG4s correlates with nucleosome repositioning on DNA. Overall, our study provides a new tool for studying G4s in cellular dynamics and highlights their association with open chromatin, transcription and their antagonism to DNA methylation.
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Affiliation(s)
- Cyril Esnault
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Talha Magat
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Amal Zine El Aabidine
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Encar Garcia-Oliver
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Anne Cucchiarini
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, Palaiseau, France
| | - Soumya Bouchouika
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - David Lleres
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Lutz Goerke
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Yu Luo
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, Palaiseau, France
- Université Paris-Saclay, Institut Curie, Orsay, France
| | - Daniela Verga
- Université Paris-Saclay, Institut Curie, Orsay, France
| | - Laurent Lacroix
- Institut de Biologie de l'École Normale Supérieure, ENS, CNRS UMR8197, Inserm U1024, Paris, France
| | - Robert Feil
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France
| | - Salvatore Spicuglia
- Aix-Marseille University, INSERM, TAGC, UMR 1090, Marseille, France
- Equipe Labellisée Ligue Contre le Cancer, Marseille, France
| | - Jean-Louis Mergny
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS, Inserm, Institut Polytechnique de Paris, Palaiseau, France
| | - Jean-Christophe Andrau
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS-UMR 5535, Montpellier, France.
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6
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Zheng KW, Zhang JY, He YD, Gong JY, Wen CJ, Chen JN, Hao YH, Zhao Y, Tan Z. Detection of genomic G-quadruplexes in living cells using a small artificial protein. Nucleic Acids Res 2020; 48:11706-11720. [PMID: 33045726 PMCID: PMC7672459 DOI: 10.1093/nar/gkaa841] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 09/16/2020] [Accepted: 09/19/2020] [Indexed: 01/08/2023] Open
Abstract
G-quadruplex (G4) structures formed by guanine-rich nucleic acids are implicated in essential physiological and pathological processes and serve as important drug targets. The genome-wide detection of G4s in living cells is important for exploring the functional role of G4s but has not yet been achieved due to the lack of a suitable G4 probe. Here we report an artificial 6.7 kDa G4 probe (G4P) protein that binds G4s with high affinity and specificity. We used it to capture G4s in living human, mouse, and chicken cells with the ChIP-Seq technique, yielding genome-wide landscape as well as details on the positions, frequencies, and sequence identities of G4 formation in these cells. Our results indicate that transcription is accompanied by a robust formation of G4s in genes. In human cells, we detected up to >123 000 G4P peaks, of which >1/3 had a fold increase of ≥5 and were present in >60% promoters and ∼70% genes. Being much smaller than a scFv antibody (27 kDa) or even a nanobody (12-15 kDa), we expect that the G4P may find diverse applications in biology, medicine, and molecular devices as a G4 affinity agent.
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Affiliation(s)
- Ke-wei Zheng
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-Sen University, Guangzhou 510275, P.R. China
| | - Jia-yu Zhang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Multidisciplinary Research Division, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, P.R. China
| | - Yi-de He
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510006, P.R. China
| | - Jia-yuan Gong
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Cui-jiao Wen
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Juan-nan Chen
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-Sen University, Guangzhou 510275, P.R. China
| | - Yu-hua Hao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Yong Zhao
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510006, P.R. China
| | - Zheng Tan
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China
- Center for Healthy Aging, Changzhi Medical College, Changzhi 046000, Shanxi, P.R. China
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7
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Joyeux M. Bacterial Nucleoid: Interplay of DNA Demixing and Supercoiling. Biophys J 2020; 118:2141-2150. [PMID: 31629479 PMCID: PMC7202931 DOI: 10.1016/j.bpj.2019.09.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/03/2019] [Accepted: 09/23/2019] [Indexed: 01/17/2023] Open
Abstract
This work addresses the question of the interplay of DNA demixing and supercoiling in bacterial cells. Demixing of DNA from other globular macromolecules results from the overall repulsion between all components of the system and leads to the formation of the nucleoid, which is the region of the cell that contains the genomic DNA in a rather compact form. Supercoiling describes the coiling of the axis of the DNA double helix to accommodate the torsional stress injected in the molecule by topoisomerases. Supercoiling is able to induce some compaction of the bacterial DNA, although to a lesser extent than demixing. In this work, we investigate the interplay of these two mechanisms with the goal of determining whether the total compaction ratio of the DNA is the mere sum or some more complex function of the compaction ratios due to each mechanism. To this end, we developed a coarse-grained bead-and-spring model and investigated its properties through Brownian dynamics simulations. This work reveals that there actually exist different regimes, depending on the crowder volume ratio and the DNA superhelical density. In particular, a regime in which the effects of DNA demixing and supercoiling on the compaction of the DNA coil simply add up is shown to exist up to moderate values of the superhelical density. In contrast, the mean radius of the DNA coil no longer decreases above this threshold and may even increase again for sufficiently large crowder concentrations. Finally, the model predicts that the DNA coil may depart from the spherical geometry very close to the jamming threshold as a trade-off between the need to minimize both the bending energy of the stiff plectonemes and the volume of the DNA coil to accommodate demixing.
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Affiliation(s)
- Marc Joyeux
- Laboratoire Interdisciplinaire de Physique, CNRS and Université Grenoble Alpes, Grenoble, France.
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8
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Zhang JY, Xia Y, Hao YH, Tan Z. DNA:RNA hybrid G-quadruplex formation upstream of transcription start site. Sci Rep 2020; 10:7429. [PMID: 32366914 PMCID: PMC7198591 DOI: 10.1038/s41598-020-64117-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 03/30/2020] [Indexed: 11/09/2022] Open
Abstract
Bioinformatic analysis reveals an enrichment of putative DNA:RNA hybrid G-quadruplex-forming sequences (PHQS) on both sides of the transcription start sites (TSSs) in the genome of warm-blooded animals, suggesting a positive selection of PHQSs in evolution and functional role of DNA:RNA hybrid G-quadruplexes (HQs) in transcription. The formation of HQs downstream of TSS in transcribed DNA has been documented under in vitro conditions; however, it is still not known if such HQs can form at the upstream side of TSSs. In this study, we report that such HQs can form in transcription in DNA with two to three guanine tracts if RNA carrying the required number of G-tracts is supplied. We also show that the formation of such HQs is dependent on the negative supercoiling generated by RNA polymerases. These results suggest that HQs may also form at the upstream side of TSSs in vivo and play a role in transcription since the two requirements are satisfied in cells.
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Affiliation(s)
- Jia-Yu Zhang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, 100101, P. R. China.,CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Multidisciplinary Research Division, Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, P. R. China
| | - Ye Xia
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, 100101, P. R. China
| | - Yu-Hua Hao
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, 100101, P. R. China
| | - Zheng Tan
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences (CAS), Beijing, 100101, P. R. China. .,Center for Healthy Aging, Changzhi Medical College, Changzhi, 046000, Shanxi, P. R. China.
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9
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Kinetics, conformation, stability, and targeting of G-quadruplexes from a physiological perspective. Biochem Biophys Res Commun 2020; 531:84-87. [PMID: 32331835 DOI: 10.1016/j.bbrc.2020.04.047] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 04/13/2020] [Indexed: 02/05/2023]
Abstract
The particular enrichment of G-quadruplex-forming sequences near transcription start sites signifies the involvement of G-quadruplexes in the regulation of transcription. The characterization of G-quadruplex formation, which holds the key to understand the function it plays in physiological and pathological processes, is mostly performed under simplified in vitro experimental conditions. Formation of G-quadruplexes in cells, however, occurs in an environment far different from the ones in which the in vitro studies on G-quadruplexes are normally carried out. Therefore, the characteristics of G-quadruplex structures obtained under the in vitro conditions may not faithfully reveal how the G-quadruplexes would behave in a physiologically relevant situation. In this mini-review, we attempt to briefly summarize the differences in a few important characteristics, including kinetics, conformation, and stability of G-quadruplex formation observed under the two conditions to illustrate how the intracellular environment might affect the behavior of G-quadruplexes largely based on the previous work carried out in the authors' laboratory. We also propose that unstable G-quadruplex variants may be better drug target candidates to improve selectivity and potency.
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10
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Gage HL, Merrick CJ. Conserved associations between G-quadruplex-forming DNA motifs and virulence gene families in malaria parasites. BMC Genomics 2020; 21:236. [PMID: 32183702 PMCID: PMC7077173 DOI: 10.1186/s12864-020-6625-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 02/26/2020] [Indexed: 11/25/2022] Open
Abstract
Background The Plasmodium genus of malaria parasites encodes several families of antigen-encoding genes. These genes tend to be hyper-variable, highly recombinogenic and variantly expressed. The best-characterized family is the var genes, exclusively found in the Laveranian subgenus of malaria parasites infecting humans and great apes. Var genes encode major virulence factors involved in immune evasion and the maintenance of chronic infections. In the human parasite P. falciparum, var gene recombination and diversification appear to be promoted by G-quadruplex (G4) DNA motifs, which are strongly associated with var genes in P. falciparum. Here, we investigated how this association might have evolved across Plasmodium species – both Laverania and also more distantly related species which lack vars but encode other, more ancient variant gene families. Results The association between var genes and G4-forming motifs was conserved across Laverania, spanning ~ 1 million years of evolutionary time, with suggestive evidence for evolution of the association occurring within this subgenus. In rodent malaria species, G4-forming motifs were somewhat associated with pir genes, but this was not conserved in the Laverania, nor did we find a strong association of these motifs with any gene family in a second outgroup of avian malaria parasites. Secondly, we compared two different G4 prediction algorithms in their performance on extremely A/T-rich Plasmodium genomes, and also compared these predictions with experimental data from G4-seq, a DNA sequencing method for identifying G4-forming motifs. We found a surprising lack of concordance between the two algorithms and also between the algorithms and G4-seq data. Conclusions G4-forming motifs are uniquely strongly associated with Plasmodium var genes, suggesting a particular role for G4s in recombination and diversification of these genes. Secondly, in the A/T-rich genomes of Plasmodium species, the choice of prediction algorithm may be particularly influential when studying G4s in these important protozoan pathogens.
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Affiliation(s)
- Hunter L Gage
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Catherine J Merrick
- Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, CB2 1QP, UK.
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11
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DDX5 helicase resolves G-quadruplex and is involved in MYC gene transcriptional activation. Proc Natl Acad Sci U S A 2019; 116:20453-20461. [PMID: 31548374 DOI: 10.1073/pnas.1909047116] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G-quadruplexes (G4) are noncanonical secondary structures formed in guanine-rich DNA and RNA sequences. MYC, one of the most critical oncogenes, forms a DNA G4 in its proximal promoter region (MycG4) that functions as a transcriptional silencer. However, MycG4 is highly stable in vitro and its regulatory role would require active unfolding. Here we report that DDX5, one of the founding members of the DEAD-box RNA helicase family, is extremely proficient at unfolding MycG4-DNA. Our results show that DDX5 is a highly active G4-resolvase that does not require a single-stranded overhang and that ATP hydrolysis is not directly coupled to G4-unfolding of DDX5. The chromatin binding sites of DDX5 are G-rich sequences. In cancer cells, DDX5 is enriched at the MYC promoter and activates MYC transcription. The DDX5 interaction with the MYC promoter and DDX5-mediated MYC activation is inhibited by G4-interactive small molecules. Our results uncover a function of DDX5 in resolving DNA and RNA G4s and suggest a molecular target to suppress MYC for cancer intervention.
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Dickerhoff J, Onel B, Chen L, Chen Y, Yang D. Solution Structure of a MYC Promoter G-Quadruplex with 1:6:1 Loop Length. ACS OMEGA 2019; 4:2533-2539. [PMID: 30842981 PMCID: PMC6396123 DOI: 10.1021/acsomega.8b03580] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
The important MYC oncogene is deregulated in many cancer cells and comprises one of the most prominent G-quadruplex (G4) forming sequences in its promoter regions, the NHE III1 motif. Formation of G4s suppresses MYC transcription and can be modulated by drug binding, establishing these DNA structures as promising targets in cancer therapy. The NHE III1 motif can fold into more than one parallel G4s, including 1:2:1 and 1:6:1 loop length conformers, with the 1:2:1 conformer shown as the major species under physiological conditions in solution. However, additional factors such as protein interactions may affect the cellular folding equilibrium. Nucleolin, a protein shown to bind MYC G4 and repress MYC transcription, is reported herein to preferably bind to the 1:6:1 loop length conformer suggesting a physiological significance of this species. The high-resolution NMR solution structure of the 1:6:1 conformer is determined, which reveals a 5'-capping structure distinctive from the 1:2:1 form, with the 6 nt central loop playing an essential role for this specific capping structure. This suggests that each parallel G-quadruplex likely adopts unique capping and loop structures determined by the specific central loop and flanking sequences. The resulting structural information at the molecular level will help to understand protein recognition of different G4s, contribution of G4 polymorphism to gene regulation, and to rationally design small molecules selectively targeting the 1:6:1 MYC G4.
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Affiliation(s)
- Jonathan Dickerhoff
- College
of Pharmacy, Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 W Stadium Avenue, West
Lafayette, Indiana 47907, United States
| | - Buket Onel
- College
of Pharmacy, Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 W Stadium Avenue, West
Lafayette, Indiana 47907, United States
| | - Luying Chen
- College
of Pharmacy, Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 W Stadium Avenue, West
Lafayette, Indiana 47907, United States
| | - Yuwei Chen
- Department
of Chemistry and Biochemistry, College of Science, University of Arizona, 1306 E. University Blvd, Tucson, Arizona 85721, United
States
| | - Danzhou Yang
- College
of Pharmacy, Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 W Stadium Avenue, West
Lafayette, Indiana 47907, United States
- Center
for Cancer Research, Purdue University, 201 S University Street, West Lafayette, Indiana 47906, United States
- Purdue
Institute for Drug Discovery, 720 Clinic Dr, West Lafayette, Indiana 47907, United
States
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