1
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Michael Sabo T, Trent JO, Chaires JB, Monsen RC. Strategy for modeling higher-order G-quadruplex structures recalcitrant to NMR determination. Methods 2024; 230:9-20. [PMID: 39032720 DOI: 10.1016/j.ymeth.2024.07.004] [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: 04/05/2024] [Revised: 06/22/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024] Open
Abstract
Guanine-rich nucleic acids can form intramolecularly folded four-stranded structures known as G-quadruplexes (G4s). Traditionally, G4 research has focused on short, highly modified DNA or RNA sequences that form well-defined homogeneous compact structures. However, the existence of longer sequences with multiple G4 repeats, from proto-oncogene promoters to telomeres, suggests the potential for more complex higher-order structures with multiple G4 units that might offer selective drug-targeting sites for therapeutic development. These larger structures present significant challenges for structural characterization by traditional high-resolution methods like multi-dimensional NMR and X-ray crystallography due to their molecular complexity. To address this current challenge, we have developed an integrated structural biology (ISB) platform, combining experimental and computational methods to determine self-consistent molecular models of higher-order G4s (xG4s). Here we outline our ISB method using two recent examples from our lab, an extended c-Myc promoter and long human telomere G4 repeats, that highlights the utility and generality of our approach to characterizing biologically relevant xG4s.
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Affiliation(s)
- T Michael Sabo
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States.
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2
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Wondimagegnhu B, Ma W, Paul T, Liao TW, Lee C, Sanford S, Opresko P, Myong S. The molecular mechanism for TERRA recruitment and annealing to telomeres. Nucleic Acids Res 2024; 52:10490-10503. [PMID: 39189448 PMCID: PMC11417404 DOI: 10.1093/nar/gkae732] [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: 04/18/2024] [Accepted: 08/16/2024] [Indexed: 08/28/2024] Open
Abstract
Telomeric repeat containing RNA (TERRA) is a noncoding RNA that is transcribed from telomeres. Previous study showed that TERRA trans anneals by invading into the telomeric duplex to form an R-loop in mammalian cells. Here, we elucidate the molecular mechanism underlying TERRA recruitment and invasion into telomeres in the context of shelterin proteins, RAD51 and RNase H using single molecule (sm) assays. We demonstrate that TERRA trans annealing into telomeric DNA exhibits dynamic movement that is stabilized by TRF2. TERRA annealing to the telomeric duplex results in the formation of a stable triplex structure which differs from a conventional R-loop. We identified that the presence of a sub-telomeric DNA and a telomeric overhang in the form of a G-quadruplex significantly enhances TERRA annealing to telomeric duplex. We also demonstrate that RAD51-TERRA complex invades telomere duplex more efficiently than TERRA alone. Additionally, TRF2 increases TERRA affinity to telomeric duplex and protects it from RNase H digestion. In contrast, TRF1 represses TERRA annealing to telomeric duplex and fails to provide protection against RNase H digestion. Our findings provide an in-depth molecular mechanism underpinning TERRA recruitment and annealing to the telomere.
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Affiliation(s)
- Bersabel Wondimagegnhu
- Program in Cell, Molecular, Developmental Biology and Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Wen Ma
- Department of Physics, The University of Vermont, Burlington, VT 05405, USA
| | - Tapas Paul
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ting-Wei Liao
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Chun Ying Lee
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Samantha Sanford
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh School of Public Health, Pittsburgh, PA 15261, USA
- UPMC Hillman Cancer Center, Pittsburgh, PA 15213, USA
| | - Sua Myong
- Program in Cell, Molecular, Developmental Biology and Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
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3
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Long W, Zeng YX, Zheng BX, Li YB, Wang YK, Chan KH, She MT, Lu YJ, Cao C, Wong WL. Targeting hTERT Promoter G-Quadruplex DNA Structures with Small-Molecule Ligand to Downregulate hTERT Expression for Triple-Negative Breast Cancer Therapy. J Med Chem 2024; 67:13363-13382. [PMID: 38987863 DOI: 10.1021/acs.jmedchem.4c01255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Human telomerase reverse transcriptase (hTERT) may have noncanonical functions in transcriptional regulation and metabolic reprogramming in cancer cells, but it is a challenging target. We thus developed small-molecule ligands targeting hTERT promoter G-quadruplex DNA structures (hTERT G4) to downregulate hTERT expression. Ligand 5 showed high affinity toward hTERT G4 (Kd = 1.1 μM) and potent activity against triple-negative breast cancer cells (MDA-MB-231, IC50 = 1 μM). In cell-based assays, 5 not only exerts markedly inhibitory activity on classical telomere functions including decreased telomerase activity, shortened telomere length, and cellular senescence but also induces DNA damage, acute cellular senescence, and apoptosis. This study reveals that hTERT G4-targeting ligand may cause mitochondrial dysfunction, disrupt iron metabolism and activate ferroptosis in cancer cells. The in vivo antitumor efficacy of 5 was also evaluated in an MDA-MB-231 xenograft mouse model and approximately 78.7% tumor weight reduction was achieved. No observable toxicity against the major organs was observed.
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Affiliation(s)
- Wei Long
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
| | - Yao-Xun Zeng
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
| | - Bo-Xin Zheng
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
| | - Yu-Bo Li
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Ya-Kun Wang
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
| | - Ka-Hin Chan
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
| | - Meng-Ting She
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
| | - Yu-Jing Lu
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology Guangzhou 510006, China
| | - Chunyang Cao
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Wing-Leung Wong
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR 999077, China
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4
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Bisoi A, Sarkar S, Singh PC. Loop nucleobases-dependent folding of G-quadruplex in normal and cancer cell-mimicking KCl microenvironments. Int J Biol Macromol 2024; 265:131050. [PMID: 38522708 DOI: 10.1016/j.ijbiomac.2024.131050] [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: 12/01/2023] [Revised: 03/05/2024] [Accepted: 03/11/2024] [Indexed: 03/26/2024]
Abstract
In this study, the folding of G-quadruplex (G4) from the telomeric DNA sequences having loop nucleobases of different chemical natures, numbers, and arrangements in 10 mM and 100 mM KCl salt conditions mimicking the cancerous and normal KCl salt microenvironments have been investigated. The data suggest that the structure and stability of the G4 are highly dependent on the KCl salt concentration. In general, the conformational flexibility of the folded G4 is higher in KCl salt relevant to cancer than in the normal case for any loop arrangements with the same number of nucleobases. The stability of the G4 decreases with the increase in the number of loop nucleobases for both salt conditions. However, the decrease in the stability of G4 having adenine in the loop region is significantly higher than the case of thymine, particularly more prominent in the KCl salt relevant to the cancer. The topology of the folded G4 and its stability also depend delicately on the permutation of the nucleobases in the loop and the salt concentrations for a particular sequence. The findings indicate that the structure and stability of G4 are noticeably different in KCl salt relevant to physiological and cancer conditions.
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Affiliation(s)
- Asim Bisoi
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Sunipa Sarkar
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Prashant Chandra Singh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
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5
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Wang C, Xu G, Liu X, Jiang L, Zhou X, Liu M, Li C. 19F Nuclear Magnetic Resonance Fingerprinting Technique for Identifying and Quantifying G-Quadruplex Topology in Human Telomeric Overhangs. J Am Chem Soc 2024; 146:4741-4751. [PMID: 38346932 DOI: 10.1021/jacs.3c12247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
G-quadruplexes (G4s) are noncanonical nucleic acid secondary structures with diverse topological features and biological roles. Human telomeric (Htelo) overhangs consisting of TTAGGG repeats can fold into G4s that adopt different topologies under physiological conditions. These G4s are potential targets for anticancer drugs. Despite intensive research, the existence and topology of G4s at Htelo overhangs in vivo are still unclear because there is no method to distinguish and quantify the topology of Htelo overhangs with native lengths that can form more than three tandem G4s in living cells. Herein, we present a novel 19F chemical shift fingerprinting technique to identify and quantify the topology of the Htelo overhangs up to five G-quadruplexes (G4s) and 120 nucleotides long both in vitro and in living cells. Our results show that longer overhang sequences tend to form stable G4s at the 5'- and 3'-ends, while the interior G4s are dynamic and "sliding" along the sequence, with TTA or 1-3 TTAGGG repeats as a linker. Each G4 in the longer overhang is conformationally heterogeneous, but the predominant ones are hybrid-2, two- or three-tetrad antiparallel, and hybrid-1 at the 5'-terminal, interior, and 3'-terminal, respectively. Additionally, we observed a distinct behavior of different lengths of telomeric sequences in living cells, suggesting that the overhang length and protein accessibility are related to its function. This technique provides a powerful tool for quickly identifying the folding topology and relative population of long Htelo overhangs, which may provide valuable insights into telomere functionality and be beneficial for structure-based anticancer drug development targeting G4s.
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Affiliation(s)
- Chen Wang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guohua Xu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Xiaoli Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Ling Jiang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Xin Zhou
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Maili Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Conggang Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
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6
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Hourvitz N, Awad A, Tzfati Y. The many faces of the helicase RTEL1 at telomeres and beyond. Trends Cell Biol 2024; 34:109-121. [PMID: 37532653 DOI: 10.1016/j.tcb.2023.07.002] [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: 04/13/2023] [Revised: 07/01/2023] [Accepted: 07/05/2023] [Indexed: 08/04/2023]
Abstract
Regulator of telomere elongation 1 (RTEL1) is known as a DNA helicase that is important for telomeres and genome integrity. However, the diverse phenotypes of RTEL1 dysfunction, the wide spectrum of symptoms caused by germline RTEL1 mutations, and the association of RTEL1 mutations with cancers suggest that RTEL1 is a complex machine that interacts with DNA, RNA, and proteins, and functions in diverse cellular pathways. We summarize the proposed functions of RTEL1 and discuss their implications for telomere maintenance. Studying RTEL1 is crucial for understanding the complex interplay between telomere maintenance and other nuclear pathways, and how compromising these pathways causes telomere biology diseases, various aging-associated pathologies, and cancer.
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Affiliation(s)
- Noa Hourvitz
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Jerusalem 91904, Israel
| | - Aya Awad
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Jerusalem 91904, Israel
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Safra Campus, Jerusalem 91904, Israel.
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7
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Zheng YY, Dartawan R, Wu Y, Wu C, Zhang H, Lu J, Hu A, Vangaveti S, Sheng J. Structural effects of inosine substitution in telomeric DNA quadruplex. Front Chem 2024; 12:1330378. [PMID: 38312345 PMCID: PMC10834636 DOI: 10.3389/fchem.2024.1330378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/08/2024] [Indexed: 02/06/2024] Open
Abstract
The telomeric DNA, a distal region of eukaryotic chromosome containing guanine-rich repetitive sequence of (TTAGGG)n, has been shown to adopt higher-order structures, specifically G-quadruplexes (G4s). Previous studies have demonstrated the implication of G4 in tumor inhibition through chromosome maintenance and manipulation of oncogene expression featuring their G-rich promoter regions. Besides higher order structures, several regulatory roles are attributed to DNA epigenetic markers. In this work, we investigated how the structural dynamics of a G-quadruplex, formed by the telomeric sequence, is affected by inosine, a prevalent modified nucleotide. We used the standard (TTAGGG)n telomere repeats with guanosine mutated to inosine at each G position. Sequences (GGG)4, (IGG)4, (GIG)4, (GGI)4, (IGI)4, (IIG)4, (GII)4, and (III)4, bridged by TTA linker, are studied using biophysical experiments and molecular modeling. The effects of metal cations in quadruplex folding were explored in both Na+ and K+ containing buffers using CD and UV-melting studies. Our results show that antiparallel quadruplex topology forms with the native sequence (GGG)4 and the terminal modified DNAs (IGG)4 and (GGI)4 in both Na+ and K+ containing buffers. Specifically, quadruplex hybrid was observed for (GGG)4 in K+ buffer. Among the other modified sequences, (GIG)4, (IGI)4 and (GII)4 show parallel features, while (IIG)4 and (III)4 show no detectable conformation in the presence of either Na+ or K+. Our studies indicate that terminal lesions (IGG)4 and (GGI)4 may induce certain unknown conformations. The folding dynamics become undetectable in the presence of more than one inosine substitution except (IGI)4 in both buffer ions. In addition, both UV melting and CD melting studies implied that in most cases the K+ cation confers more thermodynamic stability compared to Na+. Collectively, our conformational studies revealed the diverse structural polymorphisms of G4 with position dependent G-to-I mutations in different ion conditions.
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Affiliation(s)
- Ya Ying Zheng
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Ricky Dartawan
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Yuhan Wu
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Chengze Wu
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Hope Zhang
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Jeanne Lu
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Ashley Hu
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Sweta Vangaveti
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
| | - Jia Sheng
- Department of Chemistry, Albany, NY, United States
- The RNA Institute, University at Albany, State University of New York, Albany, NY, United States
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8
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Xu Y, Komiyama M. G-Quadruplexes in Human Telomere: Structures, Properties, and Applications. Molecules 2023; 29:174. [PMID: 38202757 PMCID: PMC10780218 DOI: 10.3390/molecules29010174] [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: 11/27/2023] [Revised: 12/20/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
G-quadruplexes, intricate four-stranded structures composed of G-tetrads formed by four guanine bases, are prevalent in both DNA and RNA. Notably, these structures play pivotal roles in human telomeres, contributing to essential cellular functions. Additionally, the existence of DNA:RNA hybrid G-quadruplexes adds a layer of complexity to their structural diversity. This review provides a comprehensive overview of recent advancements in unraveling the intricacies of DNA and RNA G-quadruplexes within human telomeres. Detailed insights into their structural features are presented, encompassing the latest developments in chemical approaches designed to probe these G-quadruplex structures. Furthermore, this review explores the applications of G-quadruplex structures in targeting human telomeres. Finally, the manuscript outlines the imminent challenges in this evolving field, setting the stage for future investigations.
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Affiliation(s)
- Yan Xu
- Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Makoto Komiyama
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8904, Japan
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9
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Ling X, Yao Y, Ding L, Ma J. The mechanism of UP1 binding and unfolding of human telomeric DNA G-quadruplex. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194985. [PMID: 37717939 DOI: 10.1016/j.bbagrm.2023.194985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 08/17/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023]
Abstract
The human telomere contains multiple copies of the DNA sequence d(TTAGGG) which can fold into higher order intramolecular G-quadruplexes and regulate the maintenance of telomere length and chromosomal integrity. The nucleic acid binding protein heteronuclear ribonucleoprotein A1 (hnRNP A1) and its N-terminus proteolytic product UP1 have been shown to efficiently bind and unfold telomeric DNA G-quadruplex. However, the understanding of the molecular mechanism of the UP1 binding and unfolding telomeric G-quadruplexes is still limited. Here, we performed biochemical and biophysical characterizations of UP1 binding and unfolding of human telomeric DNA G-quadruplex d[AGGG(TTAGGG)3], and in combination of systematic site-direct mutagenesis of two tandem RNA recognition motifs (RRMs) in UP1, revealed that RRM1 is responsible for initial binding and unfolding, whereas RRM2 assists RRM1 to complete the unfolding of G-quadruplex. Isothermal titration calorimetry (ITC) and circular dichroism (CD) studies of the interactions between UP1 and DNA G-quadruplex variants indicate that the "TAG" binding motif in Loop2 of telomeric G-quadruplex is critical for UP1 recognition and G-quadruplex unfolding initiation. Together we depict a model for molecular mechanism of hnRNP A1 (UP1) binding and unfolding of the human telomeric DNA G-quadruplex.
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Affiliation(s)
- Xiaobin Ling
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Yuqi Yao
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Lei Ding
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America
| | - Jinbiao Ma
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China.
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10
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Neupane A, Chariker JH, Rouchka EC. Analysis of Nucleotide Variations in Human G-Quadruplex Forming Regions Associated with Disease States. Genes (Basel) 2023; 14:2125. [PMID: 38136947 PMCID: PMC10742762 DOI: 10.3390/genes14122125] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/20/2023] [Accepted: 11/23/2023] [Indexed: 12/24/2023] Open
Abstract
While the role of G quadruplex (G4) structures has been identified in cancers and metabolic disorders, single nucleotide variations (SNVs) and their effect on G4s in disease contexts have not been extensively studied. The COSMIC and CLINVAR databases were used to detect SNVs present in G4s to identify sequence level changes and their effect on the alteration of the G4 secondary structure. A total of 37,515 G4 SNVs in the COSMIC database and 2378 in CLINVAR were identified. Of those, 7236 COSMIC (19.3%) and 457 (19%) of the CLINVAR variants result in G4 loss, while 2728 (COSMIC) and 129 (CLINVAR) SNVs gain a G4 structure. The remaining variants potentially affect the folding energy without affecting the presence of a G4. Analysis of mutational patterns in the G4 structure shows a higher selective pressure (3-fold) in the coding region on the template strand compared to the reverse strand. At the same time, an equal proportion of SNVs were observed among intronic, promoter, and enhancer regions across strands.
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Affiliation(s)
- Aryan Neupane
- School of Graduate and Interdisciplinary Studies, University of Louisville, Louisville, KY 40292, USA;
| | - Julia H. Chariker
- Department of Neuroscience Training, University of Louisville, Louisville, KY 40292, USA;
- Kentucky IDeA Network of Biomedical Research Excellence (KY INBRE) Bioinformatics Core, University of Louisville, Louisville, KY 40292, USA
| | - Eric C. Rouchka
- Kentucky IDeA Network of Biomedical Research Excellence (KY INBRE) Bioinformatics Core, University of Louisville, Louisville, KY 40292, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
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11
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Troisi R, Napolitano V, Rossitto E, Osman W, Nagano M, Wakui K, Popowicz G, Yoshimoto K, Sica F. Steric hindrance and structural flexibility shape the functional properties of a guanine-rich oligonucleotide. Nucleic Acids Res 2023; 51:8880-8890. [PMID: 37503836 PMCID: PMC10484730 DOI: 10.1093/nar/gkad634] [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: 12/15/2022] [Revised: 06/27/2023] [Accepted: 07/18/2023] [Indexed: 07/29/2023] Open
Abstract
Ligand/protein molecular recognition involves a dynamic process, whereby both partners require a degree of structural plasticity to regulate the binding/unbinding event. Here, we present the characterization of the interaction between a highly dynamic G-rich oligonucleotide, M08s-1, and its target protein, human α-thrombin. M08s-1 is the most active anticoagulant aptamer selected thus far. Circular dichroism and gel electrophoresis analyses indicate that both intramolecular and intermolecular G-quadruplex structures are populated in solution. The presence of thrombin stabilises the antiparallel intramolecular chair-like G-quadruplex conformation, that provides by far the main contribution to the biological activity of the aptamer. The crystal structure of the thrombin-oligonucleotide complex reveals that M08s-1 adopts a kinked structural organization formed by a G-quadruplex domain and a long duplex module, linked by a stretch of five purine bases. The quadruplex motif hooks the exosite I region of thrombin and the duplex region is folded towards the surface of the protein. This structural feature, which has never been observed in other anti-exosite I aptamers with a shorter duplex motif, hinders the approach of a protein substrate to the active site region and may well explain the significant increase in the anticoagulant activity of M08s-1 compared to the other anti-exosite I aptamers.
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Affiliation(s)
- Romualdo Troisi
- Department of Chemical Sciences, University of Naples Federico II, Naples 80126, Italy
| | - Valeria Napolitano
- Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
- Biomolecular NMR and Center for Integrated Protein Science Munich at Department Chemie, Technical University of Munich, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Emanuele Rossitto
- Department of Chemical Sciences, University of Naples Federico II, Naples 80126, Italy
| | - Waleed Osman
- Research and Development Division, LinkBIO Co., Ltd., The ICI Center, 5270 Terada, Toride-shi, Ibaraki 302-0021, Japan
| | - Masanobu Nagano
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Koji Wakui
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Grzegorz M Popowicz
- Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
- Biomolecular NMR and Center for Integrated Protein Science Munich at Department Chemie, Technical University of Munich, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Keitaro Yoshimoto
- Research and Development Division, LinkBIO Co., Ltd., The ICI Center, 5270 Terada, Toride-shi, Ibaraki 302-0021, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan
| | - Filomena Sica
- Department of Chemical Sciences, University of Naples Federico II, Naples 80126, Italy
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12
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Moura NMM, Cavaleiro JAS, Neves MGPMS, Ramos CIV. opp-Dibenzoporphyrin Pyridinium Derivatives as Potential G-Quadruplex DNA Ligands. Molecules 2023; 28:6318. [PMID: 37687146 PMCID: PMC10489911 DOI: 10.3390/molecules28176318] [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: 07/12/2023] [Revised: 08/12/2023] [Accepted: 08/13/2023] [Indexed: 09/10/2023] Open
Abstract
Since the occurrence of tumours is closely associated with the telomerase function and oncogene expression, the structure of such enzymes and genes are being recognized as targets for new anticancer drugs. The efficacy of several ligands in telomerase inhibition and in the regulation of genes expression, by an effective stabilisation of G-quadruplexes (G4) DNA structures, is being considered as a promising strategy in cancer therapies. When evaluating the potential of a ligand for telomerase inhibition, the selectivity towards quadruplex versus duplex DNA is a fundamental attribute due to the large amount of double-stranded DNA in the cellular nucleus. This study reports the evaluated efficacy of three tetracationic opp-dibenzoporphyrins, a free base, and the corresponding zinc(II) and nickel(II) complexes, to stabilise G4 structures, namely the telomeric DNA sequence (AG3(T2AG3)3). In order to evaluate the selectivity of these ligands towards G4 structures, their interaction towards DNA calf thymus, as a double-strand DNA sequence, were also studied. The data obtained by using different spectroscopic techniques, such as ultraviolet-visible, fluorescence, and circular dichroism, suggested good affinity of the free-base porphyrin and of its zinc(II) complex for the considered DNA structures, both showing a pattern of selectivity for the telomeric G4 structure. A pattern of aggregation in aqueous solution was detected for both Zn(II) and Ni(II) metallo dibenzoporphyrins and the ability of DNA sequences to induce ligand disaggregation was observed.
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Affiliation(s)
- Nuno M. M. Moura
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal; (J.A.S.C.); (M.G.P.M.S.N.)
| | | | | | - Catarina I. V. Ramos
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal; (J.A.S.C.); (M.G.P.M.S.N.)
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13
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Vijay Kumar MJ, Morales R, Tsvetkov AS. G-quadruplexes and associated proteins in aging and Alzheimer's disease. FRONTIERS IN AGING 2023; 4:1164057. [PMID: 37323535 PMCID: PMC10267416 DOI: 10.3389/fragi.2023.1164057] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 05/17/2023] [Indexed: 06/17/2023]
Abstract
Aging is a prominent risk factor for many neurodegenerative disorders, such as Alzheimer's disease (AD). Alzheimer's disease is characterized by progressive cognitive decline, memory loss, and neuropsychiatric and behavioral symptoms, accounting for most of the reported dementia cases. This disease is now becoming a major challenge and burden on modern society, especially with the aging population. Over the last few decades, a significant understanding of the pathophysiology of AD has been gained by studying amyloid deposition, hyperphosphorylated tau, synaptic dysfunction, oxidative stress, calcium dysregulation, and neuroinflammation. This review focuses on the role of non-canonical secondary structures of DNA/RNA G-quadruplexes (G4s, G4-DNA, and G4-RNA), G4-binding proteins (G4BPs), and helicases, and their roles in aging and AD. Being critically important for cellular function, G4s are involved in the regulation of DNA and RNA processes, such as replication, transcription, translation, RNA localization, and degradation. Recent studies have also highlighted G4-DNA's roles in inducing DNA double-strand breaks that cause genomic instability and G4-RNA's participation in regulating stress granule formation. This review emphasizes the significance of G4s in aging processes and how their homeostatic imbalance may contribute to the pathophysiology of AD.
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Affiliation(s)
- M. J. Vijay Kumar
- The Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
| | - Rodrigo Morales
- The Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
- Centro Integrativo de Biologia y Quimica Aplicada (CIBQA), Universidad Bernardo O’Higgins, Santiago, Chile
| | - Andrey S. Tsvetkov
- The Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
- UTHealth Consortium on Aging, The University of Texas McGovern Medical School, Houston, TX, United States
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14
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Wang G, Vasquez KM. Dynamic alternative DNA structures in biology and disease. Nat Rev Genet 2023; 24:211-234. [PMID: 36316397 DOI: 10.1038/s41576-022-00539-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Abstract
Repetitive elements in the human genome, once considered 'junk DNA', are now known to adopt more than a dozen alternative (that is, non-B) DNA structures, such as self-annealed hairpins, left-handed Z-DNA, three-stranded triplexes (H-DNA) or four-stranded guanine quadruplex structures (G4 DNA). These dynamic conformations can act as functional genomic elements involved in DNA replication and transcription, chromatin organization and genome stability. In addition, recent studies have revealed a role for these alternative structures in triggering error-generating DNA repair processes, thereby actively enabling genome plasticity. As a driving force for genetic variation, non-B DNA structures thus contribute to both disease aetiology and evolution.
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Affiliation(s)
- Guliang Wang
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Paediatric Research Institute, Austin, TX, USA
| | - Karen M Vasquez
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Paediatric Research Institute, Austin, TX, USA.
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15
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Bai D, Shan SW, Zhang X, Li Y, Xie J, Wu WQ. Comprehensive insights into the structures and dynamics of plant telomeric G-quadruplexes. Int J Biol Macromol 2023; 231:123281. [PMID: 36657543 DOI: 10.1016/j.ijbiomac.2023.123281] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/30/2022] [Accepted: 01/11/2023] [Indexed: 01/19/2023]
Abstract
Telomeres, which are located at the ends of eukaryotic chromosomes, are crucial for genomic maintenance. Most telomeric DNA is composed of tandemly repeated guanine (G)-rich sequences, which form G-quadruplexes (G4s). The structures and dynamics of telomeric G4s are essential for telomere functioning and helpful for G4-based biosensing. However, they are far from being understood, especially for plants. In this contribution, the folding, environment-induced G4 dynamics, and protein-catalyzed unfolding of plant telomeric G4s were comprehensively studied. It was found that diverse plant telomeric sequences from land plants to green algae could fold into G4 structures. In addition, 5'-proximal ssDNA but not 3'-proximal ssDNA drove conversion of anti-parallel G4 structures to parallel structures, and both 5' and 3' ssDNA decreased the stability of G4s in dilute solution. Furthermore, molecular crowding promoted the formation of parallel structures for three-layer but not for two-layer G4s, and increased the stability of all selected G4s. Finally, AtRecQ2 helicase resolved the stable parallel structure of typical plant telomeric G4 in crowded solution, but ssDNA binding protein AtRPA did not. Furthermore, AtRecQ2 unwound the structure more efficiently in the presence of AtRPA. The results may expand our understanding on the structures and dynamics of plant telomeric G4s.
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Affiliation(s)
- Di Bai
- State Key Laboratory of Crop Stress Adaptation and Improvement, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Song-Wang Shan
- State Key Laboratory of Crop Stress Adaptation and Improvement, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Xin Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Yan Li
- State Key Laboratory of Crop Stress Adaptation and Improvement, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Jie Xie
- State Key Laboratory of Crop Stress Adaptation and Improvement, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Wen-Qiang Wu
- State Key Laboratory of Crop Stress Adaptation and Improvement, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Henan University, Kaifeng 475004, China.
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16
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Bertini L, Libera V, Ripanti F, Natali F, Paolantoni M, Orecchini A, Nucara A, Petrillo C, Comez L, Paciaroni A. Polymorphism and Ligand Binding Modulate Fast Dynamics of Human Telomeric G-Quadruplexes. Int J Mol Sci 2023; 24:ijms24054280. [PMID: 36901712 PMCID: PMC10001961 DOI: 10.3390/ijms24054280] [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: 12/29/2022] [Revised: 02/07/2023] [Accepted: 02/15/2023] [Indexed: 02/25/2023] Open
Abstract
Telomeric G-quadruplexes (G4s) are promising targets in the design and development of anticancer drugs. Their actual topology depends on several factors, resulting in structural polymorphism. In this study, we investigate how the fast dynamics of the telomeric sequence AG3(TTAG3)3 (Tel22) depends on the conformation. By using Fourier transform Infrared spectroscopy, we show that, in the hydrated powder state, Tel22 adopts parallel and mixed antiparallel/parallel topologies in the presence of K+ and Na+ ions, respectively. These conformational differences are reflected in the reduced mobility of Tel22 in Na+ environment in the sub-nanosecond timescale, as probed by elastic incoherent neutron scattering. These findings are consistent with the G4 antiparallel conformation being more stable than the parallel one, possibly due to the presence of ordered hydration water networks. In addition, we study the effect of Tel22 complexation with BRACO19 ligand. Despite the quite similar conformation in the complexed and uncomplexed state, the fast dynamics of Tel22-BRACO19 is enhanced compared to that of Tel22 alone, independently of the ions. We ascribe this effect to the preferential binding of water molecules to Tel22 against the ligand. The present results suggest that the effect of polymorphism and complexation on the G4 fast dynamics is mediated by hydration water.
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Affiliation(s)
- Luca Bertini
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Valeria Libera
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
- CNR-IOM c/o Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Francesca Ripanti
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
- Correspondence: (F.R.); (L.C.)
| | - Francesca Natali
- CNR-IOM and INSIDE@ILL c/o OGG, 71 avenue des Martyrs, CEDEX 9, 38042 Grenoble, France
| | - Marco Paolantoni
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 6, 06123 Perugia, Italy
| | - Andrea Orecchini
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
- CNR-IOM c/o Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Alessandro Nucara
- Department of Physics, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Roma, Italy
| | - Caterina Petrillo
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
| | - Lucia Comez
- CNR-IOM c/o Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
- Correspondence: (F.R.); (L.C.)
| | - Alessandro Paciaroni
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy
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17
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Bertini L, Libera V, Ripanti F, Seydel T, Paolantoni M, Orecchini A, Petrillo C, Comez L, Paciaroni A. Role of fast dynamics in the complexation of G-quadruplexes with small molecules. Phys Chem Chem Phys 2022; 24:29232-29240. [PMID: 36445842 DOI: 10.1039/d2cp03602a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
G-quadruplexes (G4s) formed by the human telomeric sequence AG3 (TTAG3)3 (Tel22) play a key role in cancer and aging. We combined elastic incoherent neutron scattering (EINS) and quasielastic incoherent neutron scattering (QENS) to characterize the internal dynamics of Tel22 G4s and to assess how it is affected by complexation with two standard ligands, Berberine and BRACO19. We show that the interaction with the two ligands induces an increase of the overall mobility of Tel22 as quantified by the mean squared displacements (MSD) of hydrogen atoms. At the same time, the complexes display a lower stiffness than G4 alone. Two different types of motion characterize the G4 nanosecond timescale dynamics. Upon complexation, an increasing fraction of G4 atomic groups participate in this fast dynamics, along with an increase in the relevant characteristic length scales. We suggest that the entropic contribution to the conformational free energy of these motions might be crucial for the complexation mechanisms.
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Affiliation(s)
- Luca Bertini
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy.
| | - Valeria Libera
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy. .,Istituto Officina dei Materiali-IOM, National Research Council-CNR, Via Alessandro Pascoli, 06123 Perugia, Italy.
| | - Francesca Ripanti
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy.
| | - Tilo Seydel
- Institut Max von Laue - Paul Langevin (ILL) 71 avenue des Martyrs, 38042 Grenoble, France
| | - Marco Paolantoni
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto, 6, 06123 Perugia, Italy
| | - Andrea Orecchini
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy.
| | - Caterina Petrillo
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy.
| | - Lucia Comez
- Istituto Officina dei Materiali-IOM, National Research Council-CNR, Via Alessandro Pascoli, 06123 Perugia, Italy.
| | - Alessandro Paciaroni
- Department of Physics and Geology, University of Perugia, Via Alessandro Pascoli, 06123 Perugia, Italy.
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18
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Abstract
We present single-molecule experimental and computational modeling studies investigating the accessibility of human telomeric overhangs of physiologically relevant lengths. We studied 25 different overhangs that contain 4-28 repeats of GGGTTA (G-Tract) sequence and accommodate one to seven tandem G-quadruplex (GQ) structures. Using the FRET-PAINT method, we probed the distribution of accessible sites via a short imager strand, which is complementary to a G-Tract and transiently binds to available sites. We report accessibility patterns that periodically change with overhang length and interpret these patterns in terms of the underlying folding landscape and folding frustration. Overhangs that have [4n]G-Tracts, (12, 16, 20…) demonstrate the broadest accessibility patterns where the peptide nucleic acid probe accesses G-Tracts throughout the overhang. On the other hand, constructs with [4n+2]G-Tracts, (14, 18, 22…) have narrower patterns where the neighborhood of the junction between single- and double-stranded telomeres is most accessible. We interpret these results as the folding frustration being higher in [4n]G-Tract constructs compared to [4n+2]G-Tract constructs. We also developed a computational model that tests the consistency of different folding stabilities and cooperativities between neighboring GQs with the observed accessibility patterns. Our experimental and computational studies suggest the neighborhood of the junction between single- and double-stranded telomeres is least stable and most accessible, which is significant as this is a potential site where the connection between POT1/TPP1 (bound to single-stranded telomere) and other shelterin proteins (localized on double-stranded telomere) is established.
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19
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Paul T, Myong S. Helicase mediated vectorial folding of telomere G-quadruplex. Methods Enzymol 2022; 672:283-297. [DOI: 10.1016/bs.mie.2022.03.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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Liu YC, Yang DY, Sheu SY. Insights into the free energy landscape and salt-controlled mechanism of the conformational conversions between human telomeric G-quadruplex structures. Int J Biol Macromol 2021; 191:230-242. [PMID: 34536474 DOI: 10.1016/j.ijbiomac.2021.09.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/23/2021] [Accepted: 09/10/2021] [Indexed: 12/16/2022]
Abstract
G-quadruplexes have become attractive drug targets in cancer therapy. However, due to the polymorphism of G-quadruplex structures, it is difficult to experimentally verify the relevant structures of multiple intermediates and transition states in dynamic equilibrium. Hence, understanding the mechanism by which structural conversions of G-quadruplexes occur is still challenging. We conducted targeted molecular dynamics simulation with umbrella sampling to investigate how salt affects the conformational conversion of human telomeric G-quadruplex. Our results explore a unique view into the structures and energy barrier of the intermediates and transition states in the interconversion process. The pathway of G-quadruplex conformational interconversion was mapped out by a free energy landscape, consisting of branched parallel pathways with multiple energy basins. We propose a salt-controlled mechanism that as the salt concentration increases, the conformational conversion mechanism switches from multi-pathway folding to sequential folding pathways. The hybrid-I and hybrid-II structures are intermediates in the basket-propeller transformation. In high-salt solutions, the conformational conversion upon K+ binding is more feasible than upon Na+ binding. The free energy barrier for conformational conversions ranges from 1.6 to 4.6 kcal/mol. Our work will be beneficial in developing anticancer agents.
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Affiliation(s)
- Yu-Cheng Liu
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
| | - Dah-Yen Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
| | - Sheh-Yi Sheu
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
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21
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Liu Y, Zhu X, Wang K, Zhang B, Qiu S. The Cellular Functions and Molecular Mechanisms of G-Quadruplex Unwinding Helicases in Humans. Front Mol Biosci 2021; 8:783889. [PMID: 34912850 PMCID: PMC8667583 DOI: 10.3389/fmolb.2021.783889] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/02/2021] [Indexed: 01/19/2023] Open
Abstract
G-quadruplexes (G4s) are stable non-canonical secondary structures formed by G-rich DNA or RNA sequences. They play various regulatory roles in many biological processes. It is commonly agreed that G4 unwinding helicases play key roles in G4 metabolism and function, and these processes are closely related to physiological and pathological processes. In recent years, more and more functional and mechanistic details of G4 helicases have been discovered; therefore, it is necessary to carefully sort out the current research efforts. Here, we provide a systematic summary of G4 unwinding helicases from the perspective of functions and molecular mechanisms. First, we provide a general introduction about helicases and G4s. Next, we comprehensively summarize G4 unfolding helicases in humans and their proposed cellular functions. Then, we review their study methods and molecular mechanisms. Finally, we share our perspective on further prospects. We believe this review will provide opportunities for researchers to reach the frontiers in the functions and molecular mechanisms of human G4 unwinding helicases.
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Affiliation(s)
- Yang Liu
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology and Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-bioengineering, Guizhou University, Guiyang, China
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
- The Key Laboratory of Fermentation Engineering and Biological Pharmacy of Guizhou Province, Guizhou University, Guiyang, China
- School of Liquor and Food Engineering, Guizhou University, Guiyang, China
| | - Xinting Zhu
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Kejia Wang
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology and Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-bioengineering, Guizhou University, Guiyang, China
- The Key Laboratory of Fermentation Engineering and Biological Pharmacy of Guizhou Province, Guizhou University, Guiyang, China
- School of Liquor and Food Engineering, Guizhou University, Guiyang, China
| | - Bo Zhang
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Shuyi Qiu
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology and Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-bioengineering, Guizhou University, Guiyang, China
- The Key Laboratory of Fermentation Engineering and Biological Pharmacy of Guizhou Province, Guizhou University, Guiyang, China
- School of Liquor and Food Engineering, Guizhou University, Guiyang, China
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22
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Chatain J, Hatem G, Delagoutte E, Riou JF, Alberti P, Saintomé C. Multiple hPOT1-TPP1 cooperatively unfold contiguous telomeric G-quadruplexes proceeding from 3' toward 5', a feature due to a 3'-end binding preference and to structuring of telomeric DNA. Nucleic Acids Res 2021; 49:10735-10746. [PMID: 34534331 PMCID: PMC8501996 DOI: 10.1093/nar/gkab768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 08/04/2021] [Accepted: 09/15/2021] [Indexed: 02/07/2023] Open
Abstract
Telomeres are DNA repeated sequences that associate with shelterin proteins and protect the ends of eukaryotic chromosomes. Human telomeres are composed of 5'TTAGGG repeats and ends with a 3' single-stranded tail, called G-overhang, that can be specifically bound by the shelterin protein hPOT1 (human Protection of Telomeres 1). In vitro studies have shown that the telomeric G-strand can fold into stable contiguous G-quadruplexes (G4). In the present study we investigated how hPOT1, in complex with its shelterin partner TPP1, binds to telomeric sequences structured into contiguous G4 in potassium solutions. We observed that binding of multiple hPOT1-TPP1 preferentially proceeds from 3' toward 5'. We explain this directionality in terms of two factors: (i) the preference of hPOT1-TPP1 for the binding site situated at the 3' end of a telomeric sequence and (ii) the cooperative binding displayed by hPOT1-TPP1 in potassium. By comparing binding in K+ and in Li+, we demonstrate that this cooperative behaviour does not stem from protein-protein interactions, but from structuring of the telomeric DNA substrate into contiguous G4 in potassium. Our study suggests that POT1-TPP1, in physiological conditions, might preferentially cover the telomeric G-overhang starting from the 3'-end and proceeding toward 5'.
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Affiliation(s)
- Jean Chatain
- Structure et Instabilité des Génomes, Muséum national d'Histoire naturelle, CNRS, INSERM, 43 rue Cuvier, F-75005 Paris, France
| | - Georges Hatem
- Structure et Instabilité des Génomes, Muséum national d'Histoire naturelle, CNRS, INSERM, 43 rue Cuvier, F-75005 Paris, France
| | - Emmanuelle Delagoutte
- Structure et Instabilité des Génomes, Muséum national d'Histoire naturelle, CNRS, INSERM, 43 rue Cuvier, F-75005 Paris, France
| | - Jean-François Riou
- Structure et Instabilité des Génomes, Muséum national d'Histoire naturelle, CNRS, INSERM, 43 rue Cuvier, F-75005 Paris, France
| | - Patrizia Alberti
- Structure et Instabilité des Génomes, Muséum national d'Histoire naturelle, CNRS, INSERM, 43 rue Cuvier, F-75005 Paris, France
| | - Carole Saintomé
- Structure et Instabilité des Génomes, Muséum national d'Histoire naturelle, CNRS, INSERM, 43 rue Cuvier, F-75005 Paris, France.,Sorbonne Université, UFR927, F-75005 Paris, France
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23
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Ma Y, Wakabayashi Y, Watatani N, Saito R, Hirokawa T, Tera M, Nagasawa K. Vinylnaphthalene-bearing hexaoxazole as a fluorescence turn-on type G-quadruplex ligand. Org Biomol Chem 2021; 19:8035-8040. [PMID: 34492672 DOI: 10.1039/d1ob01500a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Oxazole-type fluorophores show an increase of fluorescence intensity upon interaction with nucleic acids, and therefore can be used as tools for nucleic acid-sensing and fluorescence imaging. Here, we developed a novel stilbene-type fluorophore, MO-VN (1), consisting of a mono oxazole bearing a vinyl naphthalene moiety. This compound (1) was embedded in a trioxazole 2 and a cyclic hexaoxazole 3a. The fluorescence properties of 1, 2, and 3a were evaluated in the presence of various nucleic acid sequences. Compound 3 showed significant fluorescent enhancement upon interacting with G-quadruplex (G4) structure, which plays critical roles in various biological phenomena. Further structural development focusing on the vinyl naphthalene moiety of 3a afforded a turn-on type G4 ligand 3e that shows G4-specific fluorescence. Measurement of the fluorescence of 3e during titration of a telomeric DNA, telo24, with its C-rich complementary sequence, which unwinds the G4 structure, allowed us to monitor the dynamics of G4.
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Affiliation(s)
- Yue Ma
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, To-kyo 184-8588, Japan.
| | - Yuki Wakabayashi
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Ko-ganei, Tokyo 184-8588, Japan.
| | - Naruyuki Watatani
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Ko-ganei, Tokyo 184-8588, Japan.
| | - Ryota Saito
- Department of Chemistry Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
| | - Takatsugu Hirokawa
- Transborder Medical Research center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan.,Division of Biomedical Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan.,Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ward, Tokyo 135-0064, Japan
| | - Masayuki Tera
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Ko-ganei, Tokyo 184-8588, Japan.
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Ko-ganei, Tokyo 184-8588, Japan.
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24
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Vesco G, Lamperti M, Salerno D, Marrano CA, Cassina V, Rigo R, Buglione E, Bondani M, Nicoletto G, Mantegazza F, Sissi C, Nardo L. Double-stranded flanking ends affect the folding kinetics and conformational equilibrium of G-quadruplexes forming sequences within the promoter of KIT oncogene. Nucleic Acids Res 2021; 49:9724-9737. [PMID: 34478543 PMCID: PMC8464035 DOI: 10.1093/nar/gkab674] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/13/2021] [Accepted: 09/01/2021] [Indexed: 12/01/2022] Open
Abstract
G-quadruplexes embedded within promoters play a crucial role in regulating the gene expression. KIT is a widely studied oncogene, whose promoter contains three G-quadruplex forming sequences, c-kit1, c-kit2 and c-kit*. For these sequences available studies cover ensemble and single-molecule analyses, although for kit* the latter were limited to a study on a promoter domain comprising all of them. Recently, c-kit2 has been reported to fold according to a multi-step process involving folding intermediates. Here, by exploiting fluorescence resonance energy transfer, both in ensemble and at the single molecule level, we investigated the folding of expressly designed constructs in which, alike in the physiological context, either c-kit2 or c-kit* are flanked by double stranded DNA segments. To assess whether the presence of flanking ends at the borders of the G-quadruplex affects the folding, we studied under the same protocols oligonucleotides corresponding to the minimal G-quadruplex forming sequences. Data suggest that addition of flanking ends results in biasing both the final equilibrium state and the folding kinetics. A previously unconsidered aspect is thereby unravelled, which ought to be taken into account to achieve a deeper insight of the complex relationships underlying the fine tuning of the gene-regulatory properties of these fascinating DNA structures.
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Affiliation(s)
- Guglielmo Vesco
- Department of Science and High Technology, University of Insubria, 22100 Como, Italy
| | - Marco Lamperti
- Department of Physics, Polytechnic of Milan, 23900 Lecco, Italy
| | - Domenico Salerno
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Claudia Adriana Marrano
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Valeria Cassina
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Riccardo Rigo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Enrico Buglione
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Maria Bondani
- Institute for Photonics and Nanotechnology, IFN-CNR, 22100 Como, Italy
| | - Giulia Nicoletto
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Francesco Mantegazza
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
- CRIBI Biotechnology Center, University of Padova, 35131 Padova, Italy
| | - Luca Nardo
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, University of Milano-Bicocca, 20854 Vedano al Lambro (MB), Italy
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25
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Rocher V, Genais M, Nassereddine E, Mourad R. DeepG4: A deep learning approach to predict cell-type specific active G-quadruplex regions. PLoS Comput Biol 2021; 17:e1009308. [PMID: 34383754 PMCID: PMC8384162 DOI: 10.1371/journal.pcbi.1009308] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/24/2021] [Accepted: 07/26/2021] [Indexed: 12/04/2022] Open
Abstract
DNA is a complex molecule carrying the instructions an organism needs to develop, live and reproduce. In 1953, Watson and Crick discovered that DNA is composed of two chains forming a double-helix. Later on, other structures of DNA were discovered and shown to play important roles in the cell, in particular G-quadruplex (G4). Following genome sequencing, several bioinformatic algorithms were developed to map G4s in vitro based on a canonical sequence motif, G-richness and G-skewness or alternatively sequence features including k-mers, and more recently machine/deep learning. Recently, new sequencing techniques were developed to map G4s in vitro (G4-seq) and G4s in vivo (G4 ChIP-seq) at few hundred base resolution. Here, we propose a novel convolutional neural network (DeepG4) to map cell-type specific active G4 regions (e.g. regions within which G4s form both in vitro and in vivo). DeepG4 is very accurate to predict active G4 regions in different cell types. Moreover, DeepG4 identifies key DNA motifs that are predictive of G4 region activity. We found that such motifs do not follow a very flexible sequence pattern as current algorithms seek for. Instead, active G4 regions are determined by numerous specific motifs. Moreover, among those motifs, we identified known transcription factors (TFs) which could play important roles in G4 activity by contributing either directly to G4 structures themselves or indirectly by participating in G4 formation in the vicinity. In addition, we used DeepG4 to predict active G4 regions in a large number of tissues and cancers, thereby providing a comprehensive resource for researchers. Availability: https://github.com/morphos30/DeepG4. DNA is a molecule carrying genetic information and found in all living cells. In 1953, Watson and Crick found that DNA has a double helix structure. However, other DNA structures were later identified, and most notably, G-quadruplex (G4). In 2000, the Human Genome Project revealed the widespread presence of G4s in the genome using algorithms. To date, all G4 mapping algorithms were developed to map G4s on naked DNA, without knowing if they could be formed in a given cell type. Here, we designed a novel artificial intelligence algorithm that could map G4 regions active in the cell from the DNA sequence and chromatin accessibility. Moreover, we identified key transcriptional factor motifs that could explain G4 activity depending on cell type. Lastly, we used our new algorithm to map active G4 regions in multiple tissues and cancers as a comprehensive resource for the G4 community.
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Affiliation(s)
- Vincent Rocher
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Matthieu Genais
- Centre de Recherches en Cancérologie de Toulouse (CRCT), INSERM U1037, Toulouse, France
| | - Elissar Nassereddine
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
| | - Raphael Mourad
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, Toulouse, France
- * E-mail:
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26
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Carrino S, Hennecker CD, Murrieta AC, Mittermaier A. Frustrated folding of guanine quadruplexes in telomeric DNA. Nucleic Acids Res 2021; 49:3063-3076. [PMID: 33693924 PMCID: PMC8034632 DOI: 10.1093/nar/gkab140] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 01/22/2021] [Accepted: 02/19/2021] [Indexed: 11/23/2022] Open
Abstract
Human chromosomes terminate in long, single-stranded, DNA overhangs of the repetitive sequence (TTAGGG)n. Sets of four adjacent TTAGGG repeats can fold into guanine quadruplexes (GQ), four-stranded structures that are implicated in telomere maintenance and cell immortalization and are targets in cancer therapy. Isolated GQs have been studied in detail, however much less is known about folding in long repeat sequences. Such chains adopt an enormous number of configurations containing various arrangements of GQs and unfolded gaps, leading to a highly frustrated energy landscape. To better understand this phenomenon, we used mutagenesis, thermal melting, and global analysis to determine stability, kinetic, and cooperativity parameters for GQ folding within chains containing 8–12 TTAGGG repeats. We then used these parameters to simulate the folding of 32-repeat chains, more representative of intact telomeres. We found that a combination of folding frustration and negative cooperativity between adjacent GQs increases TTAGGG unfolding by up to 40-fold, providing an abundance of unfolded gaps that are potential binding sites for telomeric proteins. This effect was most pronounced at the chain termini, which could promote telomere extension by telomerase. We conclude that folding frustration is an important and largely overlooked factor controlling the structure of telomeric DNA.
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Affiliation(s)
- Simone Carrino
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
| | - Christopher D Hennecker
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
| | - Ana C Murrieta
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada.,School of Engineering and Sciences, Instituto Tecnológico y de Estudios Superiores De Monterrey, Av. Eugenio Garza Sada 2501 Sur Col. Tecnológico C.P. 64849, Monterrey, Nuevo León, México
| | - Anthony Mittermaier
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, H3A 0B8, Canada
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27
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Mustafa G, Shiekh S, Gc K, Abeysirigunawardena S, Balci H. Interrogating accessibility of telomeric sequences with FRET-PAINT: evidence for length-dependent telomere compaction. Nucleic Acids Res 2021; 49:3371-3380. [PMID: 33693934 PMCID: PMC8034622 DOI: 10.1093/nar/gkab067] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/23/2021] [Accepted: 03/08/2021] [Indexed: 12/25/2022] Open
Abstract
Single-stranded telomeric overhangs are ∼200 nucleotides long and can form tandem G-quadruplex (GQ) structures, which reduce their accessibility to nucleases and proteins that activate DNA damage response. Whether these tandem GQs further stack to form compact superstructures, which may provide better protection for longer telomeres, is not known. We report single-molecule measurements where the accessibility of 24-144 nucleotide long human telomeric DNA molecules is interrogated by a short PNA molecule that is complementary to a single GGGTTA repeat, as implemented in the FRET-PAINT method. Binding of the PNA strand to available GGGTTA sequences results in discrete FRET bursts which were analyzed in terms of their dwell times, binding frequencies, and topographic distributions. The binding frequencies were greater for binding to intermediate regions of telomeric DNA compared to 3'- or 5'-ends, suggesting these regions are more accessible. Significantly, the binding frequency per telomeric repeat monotonically decreased with increasing telomere length. These results are consistent with telomeres forming more compact structures at longer lengths, reducing accessibility of these critical genomic sites.
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Affiliation(s)
- Golam Mustafa
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | - Keshav Gc
- Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA
| | | | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA
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28
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An all-in-one telomerase assay based on CRISPR-Cas12a trans-cleavage while telomere synthesis. Anal Chim Acta 2021; 1159:338404. [PMID: 33867038 DOI: 10.1016/j.aca.2021.338404] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/25/2021] [Accepted: 02/28/2021] [Indexed: 12/26/2022]
Abstract
As one of the crucial factors associated with human life span and cancer progression, telomerase is regarded as an emerging biomarker for cancer diagnosis. Therefore, a facile, rapid and sensitive approach for telomerase activity detection with point-of-care (POC) diagnosis potential is in great demands. Herein, an all-in-one telomerase activity detection assay was established based on the telomere synthesis activated CRISPR-Cas12a system. A telomerase extension reaction generated telomere repeats sequences (TTAGGG)n, which was recognized by a customized CRISPR-guided RNA (crRNA) simultaneously, and finally activated a typical trans-cleavage based CRISPR-Cas12a detection assay. With the inherent sensitivity of CRISPR-Cas12a, this approach achieved a great linear regression ranging from 100 to 2000 HeLa cells and a limitation of detection down to 26 HeLa cells. Moreover, by using the proposed method, telomerase can be detected in one pot under isothermal condition (37 °C) by a simple and fast workflow (one step within 1 h). Due to its excellent performance, this all-in-one method shows great potential in POC detection of the telomerase activity.
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29
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Fluorene/fluorenone carboxamide derivatives as selective light-up fluorophores for c-myc G-quadruplex. Bioorg Med Chem Lett 2021; 36:127824. [PMID: 33513388 DOI: 10.1016/j.bmcl.2021.127824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/01/2021] [Accepted: 01/19/2021] [Indexed: 12/11/2022]
Abstract
The development of fluorescent dyes capable of selective recognition of G-quadruplexes is essential for studying its localization and biological functions. However, considering the G-quadruplex topologies may vary significantly, the synthesis of compounds showing both selectivity and strong fluorescence properties still remains a great challenge. Recently we have developed fluorene/fluorenone derivatives with structure-specific binding towards dsRNA, indicating its potential for structure-selective ligands. Herein, we report the synthesis of novel fluorene/fluorenone derivatives and their selectivity towards various DNA structures, particularly G-quadruplexes, two of which showed strong affinity to the proto-oncogene c-myc promoter G-quadruplex.
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30
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Lejault P, Mitteaux J, Sperti FR, Monchaud D. How to untie G-quadruplex knots and why? Cell Chem Biol 2021; 28:436-455. [PMID: 33596431 DOI: 10.1016/j.chembiol.2021.01.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/08/2020] [Accepted: 01/20/2021] [Indexed: 12/12/2022]
Abstract
For over two decades, the prime objective of the chemical biology community studying G-quadruplexes (G4s) has been to use chemicals to interact with and stabilize G4s in cells to obtain mechanistic interpretations. This strategy has been undoubtedly successful, as demonstrated by recent advances. However, these insights have also led to a fundamental rethinking of G4-targeting strategies: due to the prevalence of G4s in the human genome, transcriptome, and ncRNAome (collectively referred to as the G4ome), and their involvement in human diseases, should we continue developing G4-stabilizing ligands or should we invest in designing molecular tools to unfold G4s? Here, we first focus on how, when, and where G4s fold in cells; then, we describe the enzymatic systems that have evolved to counteract G4 folding and how they have been used as tools to manipulate G4s in cells; finally, we present strategies currently being implemented to devise new molecular G4 unwinding agents.
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Affiliation(s)
- Pauline Lejault
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - Jérémie Mitteaux
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - Francesco Rota Sperti
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - David Monchaud
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France.
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31
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Active and Passive Destabilization of G-Quadruplex DNA by the Telomere POT1-TPP1 Complex. J Mol Biol 2021; 433:166846. [PMID: 33549587 DOI: 10.1016/j.jmb.2021.166846] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 01/05/2021] [Accepted: 01/22/2021] [Indexed: 11/23/2022]
Abstract
Chromosome ends are protected by guanosine-rich telomere DNA that forms stable G-quadruplex (G4) structures. The heterodimeric POT1-TPP1 complex interacts specifically with telomere DNA to shield it from illicit DNA damage repair and to resolve secondary structure that impedes telomere extension. The mechanism by which POT1-TPP1 accomplishes these tasks is poorly understood. Here, we establish the kinetic framework for POT1-TPP1 binding and unfolding of telomere G4 DNA. Our data identify two modes of POT1-TPP1 destabilization of G4 DNA that are governed by protein concentration. At low concentrations, POT1-TPP1 passively captures transiently unfolded G4s. At higher concentrations, POT1-TPP1 proteins bind to G4s to actively destabilize the DNA structures. Cancer-associated POT1-TPP1 mutations impair multiple reaction steps in this process, resulting in less efficient destabilization of G4 structures. The mechanistic insight highlights the importance of cell cycle dependent expression and localization of the POT1-TPP1 complex and distinguishes diverse functions of this complex in telomere maintenance.
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32
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Kumari N, Raghavan SC. G-quadruplex DNA structures and their relevance in radioprotection. Biochim Biophys Acta Gen Subj 2021; 1865:129857. [PMID: 33508382 DOI: 10.1016/j.bbagen.2021.129857] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND DNA, the genetic material of most of the organisms, is the crucial element of life. Integrity of DNA needs to be maintained for transmission of genetic material from one generation to another. All organisms are constantly challenged by the environmental conditions which can lead to the induction of DNA damage. Ionizing radiation (IR) has been known to induce DNA damage and IR sensitivity varies among different organisms. The causes for differential radiosensitivity among various organisms have not been studied in great detail. SCOPE OF REVIEW We discuss DNA secondary structure formation, GC content of the genome, role of G-quadruplex formation, and its relationship with radiosensitivity of the genome. MAJOR CONCLUSION In Deinococcus radiodurans, the bacterium that exhibits maximum radio resistance, multiple G-quadruplex forming motifs are reported. In human cells, G-quadruplex formation led to differential radiosensitivity. In this article, we have discussed, the role of secondary DNA structure formation like G-quadruplex in shielding the genome from radiation and its implications in understanding evolution of radio protective effect of an organism. We also discuss role of GC content and its correlation with radio resistance. GENERAL SIGNIFICANCE This review provides an insight into the role of G-quadruplexes in providing differential radiosensitivity at different site of the genome and in different organisms. It further discusses the possibility of higher GC content contributing towards reduced radiosensitivity in different organisms, evolution of radiosensitivity, and regulation of multiple cellular processes.
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Affiliation(s)
- Nitu Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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33
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Zhang R, Xiao K, Gu Y, Liu H, Sun X. Whole Genome Identification of Potential G-Quadruplexes and Analysis of the G-Quadruplex Binding Domain for SARS-CoV-2. Front Genet 2020; 11:587829. [PMID: 33329730 PMCID: PMC7728997 DOI: 10.3389/fgene.2020.587829] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/22/2020] [Indexed: 01/08/2023] Open
Abstract
The coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has become a global public health emergency. G-quadruplex, one of the non-canonical secondary structures, has shown potential antiviral values. However, little is known about the G-quadruplexes of the emerging SARS-CoV-2. Herein, we characterized the potential G-quadruplexes in both positive and negative-sense viral strands. The identified potential G-quadruplexes exhibited similar features to the G-quadruplexes detected in the human transcriptome. Within some bat- and pangolin-related betacoronaviruses, the G-tracts rather than the loops were under heightened selective constraints. We also found that the amino acid sequence similar to SUD (SARS-unique domain) was retained in SARS-CoV-2 but depleted in some other coronaviruses that can infect humans. Further analysis revealed that the amino acid residues related to the binding affinity of G-quadruplexes were conserved among 16,466 SARS-CoV-2 samples. Moreover, the dimer of the SUD-homology structure in SARS-CoV-2 displayed similar electrostatic potential patterns to the SUD dimer from SARS. Considering the potential value of G-quadruplexes to serve as targets in antiviral strategy, our fundamental research could provide new insights for the SARS-CoV-2 drug discovery.
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Affiliation(s)
| | | | | | | | - Xiao Sun
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
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34
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Yasuda M, Ma Y, Okabe S, Wakabayashi Y, Su D, Chang YT, Seimiya H, Tera M, Nagasawa K. Target identification of a macrocyclic hexaoxazole G-quadruplex ligand using post-target-binding visualization. Chem Commun (Camb) 2020; 56:12905-12908. [PMID: 33030187 DOI: 10.1039/d0cc04957c] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Macrocyclic hexaoxazoles (6OTDs) are G-quadruplex (G4) ligands, and some derivatives, such as L2H2-6OTD (1a) bearing two aminobutyl side chains, show cytotoxicity towards cancer cells. To identify the cellular target of 1a, we employed a post-target-binding strategy utilizing click reaction (Huisgen cyclization) between the azide-conjugated ligand L2H2-6OTD-Az (1b) and the cell-permeable dye CO-1 bearing a strained alkyne moiety and the BODIPY fluorophore under Cu-free conditions. We confirmed that introduction of the small azide group did not alter the physical or biological properties, including anti-cancer activity, of 1a, and we also demonstrated bias-free localization of CO-1. The post-binding visualization strategy suggested that L2H2-6OTD (1a) colocalized with RNA G4 in living cells.
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Affiliation(s)
- Mizuho Yasuda
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
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35
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Lim G, Hohng S. Single-molecule fluorescence studies on cotranscriptional G-quadruplex formation coupled with R-loop formation. Nucleic Acids Res 2020; 48:9195-9203. [PMID: 32810236 PMCID: PMC7498336 DOI: 10.1093/nar/gkaa695] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 01/13/2023] Open
Abstract
G-quadruplex (GQ) is formed at various regions of DNA, including telomeres of chromosomes and regulatory regions of oncogenes. Since GQ is important in both gene regulation and genome instability, the biological and medical implications of this abnormal DNA structure have been intensively studied. Its formation mechanisms, however, are not clearly understood yet. We report single-molecule fluorescence experiments to monitor the cotranscriptional GQ formation coupled with R-loop formation using T7 RNA polymerase. The GQ is formed very rarely per single-round transcription. R-loop formation precedes and facilitates GQ formation. Once formed, some GQs are extremely stable, resistant even to RNase H treatment, and accumulate in multiple-round transcription conditions. On the other hand, GQ existing in the non-template strand promotes the R-loop formation in the next rounds of transcription. Our study clearly shows the existence of a positive feedback mechanism of GQ and R-loop formations, which may possibly contribute to gene regulation and genome instability.
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Affiliation(s)
- Gunhyoung Lim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
| | - Sungchul Hohng
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Republic of Korea
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36
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Imperatore C, Varriale A, Rivieccio E, Pennacchio A, Staiano M, D’Auria S, Casertano M, Altucci C, Valadan M, Singh M, Menna M, Varra M. Spectroscopic Properties of Two 5'-(4-Dimethylamino)Azobenzene Conjugated G-Quadruplex Forming Oligonucleotides. Int J Mol Sci 2020; 21:E7103. [PMID: 32993097 PMCID: PMC7582650 DOI: 10.3390/ijms21197103] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/10/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
The synthesis of two 5'-end (4-dimethylamino)azobenzene conjugated G-quadruplex forming aptamers, the thrombin binding aptamer (TBA) and the HIV-1 integrase aptamer (T30695), was performed. Their structural behavior was investigated by means of UV, CD, fluorescence spectroscopy, and gel electrophoresis techniques in K+-containing buffers and water-ethanol blends. Particularly, we observed that the presence of the 5'-(4-dimethylamino)azobenzene moiety leads TBA to form multimers instead of the typical monomolecular chair-like G-quadruplex and almost hampers T30695 G-quadruplex monomers to dimerize. Fluorescence studies evidenced that both the conjugated G-quadruplexes possess unique fluorescence features when excited at wavelengths corresponding to the UV absorption of the conjugated moiety. Furthermore, a preliminary investigation of the trans-cis conversion of the dye incorporated at the 5'-end of TBA and T30695 showed that, unlike the free dye, in K+-containing water-ethanol-triethylamine blend the trans-to-cis conversion was almost undetectable by means of a standard UV spectrophotometer.
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Affiliation(s)
- Concetta Imperatore
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Antonio Varriale
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Elisa Rivieccio
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Angela Pennacchio
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Maria Staiano
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Sabato D’Auria
- Institute of Food Sciences, National Research Council of Italy, via Roma 64, 83100 Avellino, Italy; (A.V.); (A.P.); (M.S.); (S.D.)
| | - Marcello Casertano
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Carlo Altucci
- Department of Physics “Ettore Pancini”, University of Naples Federico II, Via Cinthia, 21—Building 6, 80126 Naples, Italy; (C.A.); (M.V.); (M.S.)
| | - Mohammadhassan Valadan
- Department of Physics “Ettore Pancini”, University of Naples Federico II, Via Cinthia, 21—Building 6, 80126 Naples, Italy; (C.A.); (M.V.); (M.S.)
| | - Manjot Singh
- Department of Physics “Ettore Pancini”, University of Naples Federico II, Via Cinthia, 21—Building 6, 80126 Naples, Italy; (C.A.); (M.V.); (M.S.)
| | - Marialuisa Menna
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
| | - Michela Varra
- Department of Pharmacy, School of Medicine, University of Naples “Federico II”, Via D. Montesano 49, 80131 Naples, Italy; (C.I.); (E.R.); (M.C.); (M.M.)
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37
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Kamal S, Junaid M, Ejaz A, Bibi I, Akash MSH, Rehman K. The secrets of telomerase: Retrospective analysis and future prospects. Life Sci 2020; 257:118115. [PMID: 32698073 DOI: 10.1016/j.lfs.2020.118115] [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: 04/20/2020] [Revised: 07/06/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022]
Abstract
Telomerase plays a significant role to maintain and regulate the telomere length, cellular immortality and senescence by the addition of guanine-rich repetitive sequences. Chronic inflammation or oxidative stress-induced infection downregulates TERT gene modifying telomerase activity thus contributing to the early steps of gastric carcinogenesis process. Furthermore, telomere-telomerase system performs fundamental role in the pathogenesis and progression of diabetes mellitus as well as in its vascular intricacy. The cessation of cell proliferation in cultured cells by inhibiting the telomerase activity of transformed cells renders the rationale for culling of telomerase as a target therapy for the treatment of metabolic disorders and various types of cancers. In this article, we have briefly described the role of immune system and malignant cells in the expression of telomerase with critical analysis on the gaps and potential for future studies. The key findings regarding the secrets of the telomerase summarized in this article will help in future treatment modalities for the prevention of various types of cancers and metabolic disorders notably diabetes mellitus.
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Affiliation(s)
- Shagufta Kamal
- Department of Biochemistry, Government College University Faisalabad, Pakistan
| | - Muhammad Junaid
- Department of Biochemistry, Government College University Faisalabad, Pakistan
| | - Arslan Ejaz
- Department of Biochemistry, Government College University Faisalabad, Pakistan
| | - Ismat Bibi
- Department of Chemistry, Islamia University, Bahawalpur, Pakistan
| | | | - Kanwal Rehman
- Department of Pharmacy, University of Agriculture, Faisalabad, Pakistan.
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38
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Monsen RC, DeLeeuw L, Dean WL, Gray RD, Sabo T, Chakravarthy S, Chaires JB, Trent JO. The hTERT core promoter forms three parallel G-quadruplexes. Nucleic Acids Res 2020; 48:5720-5734. [PMID: 32083666 PMCID: PMC7261196 DOI: 10.1093/nar/gkaa107] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/06/2020] [Accepted: 02/17/2020] [Indexed: 12/13/2022] Open
Abstract
The structure of the 68 nt sequence with G-quadruplex forming potential within the hTERT promoter is disputed. One model features a structure with three stacked parallel G-quadruplex units, while another features an unusual duplex hairpin structure adjoined to two stacked parallel and antiparallel quadruplexes. We report here the results of an integrated structural biology study designed to distinguish between these possibilities. As part of our study, we designed a sequence with an optimized hairpin structure and show that its biophysical and biochemical properties are inconsistent with the structure formed by the hTERT wild-type sequence. By using circular dichroism, thermal denaturation, nuclear magnetic resonance spectroscopy, analytical ultracentrifugation, small-angle X-ray scattering, molecular dynamics simulations and a DNase I cleavage assay we found that the wild type hTERT core promoter folds into a stacked, three-parallel G-quadruplex structure. The hairpin structure is inconsistent with all of our experimental data obtained with the wild-type sequence. All-atom models for both structures were constructed using molecular dynamics simulations. These models accurately predicted the experimental hydrodynamic properties measured for each structure. We found with certainty that the wild-type hTERT promoter sequence does not form a hairpin structure in solution, but rather folds into a compact stacked three-G-quadruplex conformation.
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Affiliation(s)
- Robert C Monsen
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - Lynn DeLeeuw
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - William L Dean
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - T Michael Sabo
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
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39
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Vannutelli A, Belhamiti S, Garant JM, Ouangraoua A, Perreault JP. Where are G-quadruplexes located in the human transcriptome? NAR Genom Bioinform 2020; 2:lqaa035. [PMID: 33575590 PMCID: PMC7671396 DOI: 10.1093/nargab/lqaa035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/28/2020] [Accepted: 05/05/2020] [Indexed: 12/23/2022] Open
Abstract
It has been demonstrated that RNA G-quadruplexes (G4) are structural motifs present in transcriptomes and play important regulatory roles in several post-transcriptional mechanisms. However, the full picture of RNA G4 locations and the extent of their implication remain elusive. Solely computational prediction analysis of the whole transcriptome may reveal all potential G4, since experimental identifications are always limited to specific conditions or specific cell lines. The present study reports the first in-depth computational prediction of potential G4 region across the complete human transcriptome. Although using a relatively stringent approach based on three prediction scores that accounts for the composition of G4 sequences, the composition of their neighboring sequences, and the various forms of G4, over 1.1 million of potential G4 (pG4) were predicted. The abundance of G4 was computationally confirmed in both 5' and 3'UTR as well as splicing junction of mRNA, appreciate for the first time in the long ncRNA, while almost absent of most of the small ncRNA families. The present results constitute an important step toward a full understanding of the roles of G4 in post-transcriptional mechanisms.
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Affiliation(s)
- Anaïs Vannutelli
- Department of Computer Science, Faculté des sciences, Université de Sherbrooke, QC J1K 2R1, Canada
- Department of Biochemistry and Functional Genomics, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, QC J1E 4K8, Canada
| | - Sarah Belhamiti
- Department of Computer Science, Faculté des sciences, Université de Sherbrooke, QC J1K 2R1, Canada
- Department of Biochemistry and Functional Genomics, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, QC J1E 4K8, Canada
| | - Jean-Michel Garant
- Department of Biochemistry and Functional Genomics, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, QC J1E 4K8, Canada
| | - Aida Ouangraoua
- Department of Computer Science, Faculté des sciences, Université de Sherbrooke, QC J1K 2R1, Canada
| | - Jean-Pierre Perreault
- Department of Biochemistry and Functional Genomics, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, QC J1E 4K8, Canada
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40
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G-quadruplex, Friend or Foe: The Role of the G-quartet in Anticancer Strategies. Trends Mol Med 2020; 26:848-861. [PMID: 32467069 DOI: 10.1016/j.molmed.2020.05.002] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 05/06/2020] [Indexed: 02/07/2023]
Abstract
The clinical applicability of G-quadruplexes (G4s) as anticancer drugs is currently being evaluated. Several G4 ligands and aptamers are undergoing clinical trials following the notable examples of quarfloxin and AS1411, respectively. In this review, we summarize the latest achievements and breakthroughs in the use of G4 nucleic acids as both therapeutic tools ('friends', as healing anticancer drugs) and targets ('foes', within the harmful cancer cell), particularly using aptamers and quadruplex-targeted ligands, respectively. We explore the recent research on synthetic G4 ligands toward the discovery of anticancer therapeutics and their mechanism of action. Additionally, we highlight recent advances in chemical and structural biology that enable the design of specific G4 aptamers to be used as novel anticancer agents.
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41
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Mitra J, Ha T. Streamlining effects of extra telomeric repeat on telomeric DNA folding revealed by fluorescence-force spectroscopy. Nucleic Acids Res 2020; 47:11044-11056. [PMID: 31617570 PMCID: PMC6868435 DOI: 10.1093/nar/gkz906] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 09/29/2019] [Accepted: 10/02/2019] [Indexed: 01/26/2023] Open
Abstract
A human telomere ends in a single-stranded 3′ tail, composed of repeats of T2AG3. G-quadruplexes (GQs) formed from four consecutive repeats have been shown to possess high-structural and mechanical diversity. In principle, a GQ can form from any four repeats that are not necessarily consecutive. To understand the dynamics of GQs with positional multiplicity, we studied five and six repeats human telomeric sequence using a combination of single molecule FRET and optical tweezers. Our results suggest preferential formation of GQs at the 3′ end both in K+ and Na+ solutions, with minor populations of 5′-GQ or long-loop GQs. A vectorial folding assay which mimics the directional nature of telomere extension showed that the 3′ preference holds even when folding is allowed to begin from the 5′ side. In 100 mM K+, the unassociated T2AG3 segment has a streamlining effect in that one or two mechanically distinct species was observed at a single position instead of six or more observed without an unassociated repeat. We did not observe such streamlining effect in 100 mM Na+. Location of GQ and reduction in conformational diversity in the presence of extra repeats have implications in telomerase inhibition, T-loop formation and telomere end protection.
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Affiliation(s)
- Jaba Mitra
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana IL 61801, USA.,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA.,Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.,Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, MD 21218, USA
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42
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Wu WQ, Zhang ML, Song CP. A comprehensive evaluation of a typical plant telomeric G-quadruplex (G4) DNA reveals the dynamics of G4 formation, rearrangement, and unfolding. J Biol Chem 2020; 295:5461-5469. [PMID: 32184352 PMCID: PMC7170514 DOI: 10.1074/jbc.ra119.012383] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/16/2020] [Indexed: 11/06/2022] Open
Abstract
Telomeres are specific nucleoprotein structures that are located at the ends of linear eukaryotic chromosomes and play crucial roles in genomic stability. Telomere DNA consists of simple repeats of a short G-rich sequence: TTAGGG in mammals and TTTAGGG in most plants. In recent years, the mammalian telomeric G-rich repeats have been shown to form G-quadruplex (G4) structures, which are crucial for modulating telomere functions. Surprisingly, even though plant telomeres are essential for plant growth, development, and environmental adaptions, only few reports exist on plant telomeric G4 DNA (pTG4). Here, using bulk and single-molecule assays, including CD spectroscopy, and single-molecule FRET approaches, we comprehensively characterized the structure and dynamics of a typical plant telomeric sequence, d[GGG(TTTAGGG)3]. We found that this sequence can fold into mixed G4s in potassium, including parallel and antiparallel structures. We also directly detected intermediate dynamic transitions, including G-hairpin, parallel G-triplex, and antiparallel G-triplex structures. Moreover, we observed that pTG4 is unfolded by the AtRecQ2 helicase but not by AtRecQ3. The results of our work shed light on our understanding about the existence, topological structures, stability, intermediates, unwinding, and functions of pTG4.
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Affiliation(s)
- Wen-Qiang Wu
- State Key Laboratory of Crop Stress Adaptation and Improvement, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng 475001, China
| | - Ming-Li Zhang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng 475001, China
| | - Chun-Peng Song
- State Key Laboratory of Crop Stress Adaptation and Improvement, Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng 475001, China.
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43
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Nuthanakanti A, Ahmed I, Khatik SY, Saikrishnan K, Srivatsan SG. Probing G-quadruplex topologies and recognition concurrently in real time and 3D using a dual-app nucleoside probe. Nucleic Acids Res 2020; 47:6059-6072. [PMID: 31106340 PMCID: PMC6614846 DOI: 10.1093/nar/gkz419] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/30/2019] [Accepted: 05/06/2019] [Indexed: 12/30/2022] Open
Abstract
Comprehensive understanding of structure and recognition properties of regulatory nucleic acid elements in real time and atomic level is highly important to devise efficient therapeutic strategies. Here, we report the establishment of an innovative biophysical platform using a dual-app nucleoside analog, which serves as a common probe to detect and correlate different GQ structures and ligand binding under equilibrium conditions and in 3D by fluorescence and X-ray crystallography techniques. The probe (SedU) is composed of a microenvironment-sensitive fluorophore and an excellent anomalous X-ray scatterer (Se), which is assembled by attaching a selenophene ring at 5-position of 2'-deoxyuridine. SedU incorporated into the loop region of human telomeric DNA repeat fluorescently distinguished subtle differences in GQ topologies and enabled quantify ligand binding to different topologies. Importantly, anomalous X-ray dispersion signal from Se could be used to determine the structure of GQs. As the probe is minimally perturbing, a direct comparison of fluorescence data and crystal structures provided structural insights on how the probe senses different GQ conformations without affecting the native fold. Taken together, our dual-app probe represents a new class of tool that opens up new experimental strategies to concurrently investigate nucleic acid structure and recognition in real time and 3D.
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Affiliation(s)
- Ashok Nuthanakanti
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
| | - Ishtiyaq Ahmed
- Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
| | - Saddam Y Khatik
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
| | - Kayarat Saikrishnan
- Department of Biology, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
- Correspondence may also be addressed to Kayarat Saikrishnan.
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune 411008, India
- To whom correspondence should be addressed. Tel: +91 2025908086;
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44
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Structural Features of Nucleoprotein CST/Shelterin Complex Involved in the Telomere Maintenance and Its Association with Disease Mutations. Cells 2020; 9:cells9020359. [PMID: 32033110 PMCID: PMC7072152 DOI: 10.3390/cells9020359] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 12/29/2022] Open
Abstract
Telomere comprises the ends of eukaryotic linear chromosomes and is composed of G-rich (TTAGGG) tandem repeats which play an important role in maintaining genome stability, premature aging and onsets of many diseases. Majority of the telomere are replicated by conventional DNA replication, and only the last bit of the lagging strand is synthesized by telomerase (a reverse transcriptase). In addition to replication, telomere maintenance is principally carried out by two key complexes known as shelterin (TRF1, TRF2, TIN2, RAP1, POT1, and TPP1) and CST (CDC13/CTC1, STN1, and TEN1). Shelterin protects the telomere from DNA damage response (DDR) and regulates telomere length by telomerase; while, CST govern the extension of telomere by telomerase and C strand fill-in synthesis. We have investigated both structural and biochemical features of shelterin and CST complexes to get a clear understanding of their importance in the telomere maintenance. Further, we have analyzed ~115 clinically important mutations in both of the complexes. Association of such mutations with specific cellular fault unveils the importance of shelterin and CST complexes in the maintenance of genome stability. A possibility of targeting shelterin and CST by small molecule inhibitors is further investigated towards the therapeutic management of associated diseases. Overall, this review provides a possible direction to understand the mechanisms of telomere borne diseases, and their therapeutic intervention.
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45
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POT1-TPP1 differentially regulates telomerase via POT1 His266 and as a function of single-stranded telomere DNA length. Proc Natl Acad Sci U S A 2019; 116:23527-23533. [PMID: 31685617 PMCID: PMC6876245 DOI: 10.1073/pnas.1905381116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Telomeres cap the ends of linear chromosomes and terminate in a single-stranded DNA (ssDNA) overhang recognized by POT1-TPP1 heterodimers to help regulate telomere length homeostasis. Here hydroxyl radical footprinting coupled with mass spectrometry was employed to probe protein-protein interactions and conformational changes involved in the assembly of telomere ssDNA substrates of differing lengths bound by POT1-TPP1 heterodimers. Our data identified environmental changes surrounding residue histidine 266 of POT1 that were dependent on telomere ssDNA substrate length. We further determined that the chronic lymphocytic leukemia-associated H266L substitution significantly reduced POT1-TPP1 binding to short ssDNA substrates; however, it only moderately impaired the heterodimer binding to long ssDNA substrates containing multiple protein binding sites. Additionally, we identified a telomerase inhibitory role when several native POT1-TPP1 proteins coat physiologically relevant lengths of telomere ssDNA. This POT1-TPP1 complex-mediated inhibition of telomerase is abrogated in the context of the POT1 H266L mutation, which leads to telomere overextension in a malignant cellular environment.
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46
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Lansdorp P, van Wietmarschen N. Helicases FANCJ, RTEL1 and BLM Act on Guanine Quadruplex DNA in Vivo. Genes (Basel) 2019; 10:genes10110870. [PMID: 31683575 PMCID: PMC6896191 DOI: 10.3390/genes10110870] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 10/29/2019] [Accepted: 10/29/2019] [Indexed: 02/03/2023] Open
Abstract
Guanine quadruplex (G4) structures are among the most stable secondary DNA structures that can form in vitro, and evidence for their existence in vivo has been steadily accumulating. Originally described mainly for their deleterious effects on genome stability, more recent research has focused on (potential) functions of G4 structures in telomere maintenance, gene expression, and other cellular processes. The combined research on G4 structures has revealed that properly regulating G4 DNA structures in cells is important to prevent genome instability and disruption of normal cell function. In this short review we provide some background and historical context of our work resulting in the identification of FANCJ, RTEL1 and BLM as helicases that act on G4 structures in vivo. Taken together these studies highlight important roles of different G4 DNA structures and specific G4 helicases at selected genomic locations and telomeres in regulating gene expression and maintaining genome stability.
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Affiliation(s)
- Peter Lansdorp
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC V5Z 1L3, Canada.
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada.
- European Research Institute for the Biology of Ageing, University of Groningen, 9713 AV Groningen, The Netherlands.
| | - Niek van Wietmarschen
- European Research Institute for the Biology of Ageing, University of Groningen, 9713 AV Groningen, The Netherlands.
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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47
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Mukherjee AK, Sharma S, Bagri S, Kutum R, Kumar P, Hussain A, Singh P, Saha D, Kar A, Dash D, Chowdhury S. Telomere repeat-binding factor 2 binds extensively to extra-telomeric G-quadruplexes and regulates the epigenetic status of several gene promoters. J Biol Chem 2019; 294:17709-17722. [PMID: 31575660 PMCID: PMC6879327 DOI: 10.1074/jbc.ra119.008687] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 09/18/2019] [Indexed: 12/22/2022] Open
Abstract
The role of the telomere repeat-binding factor 2 (TRF2) in telomere maintenance is well-established. However, recent findings suggest that TRF2 also functions outside telomeres, but relatively little is known about this function. Herein, using genome-wide ChIP-Seq assays of TRF2-bound chromatin from HT1080 fibrosarcoma cells, we identified thousands of TRF2-binding sites within the extra-telomeric genome. In light of this observation, we asked how TRF2 occupancy is organized within the genome. Interestingly, we found that extra-telomeric TRF2 sites throughout the genome are enriched in potential G-quadruplex-forming DNA sequences. Furthermore, we validated TRF2 occupancy at several promoter G-quadruplex motifs, which did adopt quadruplex forms in solution. TRF2 binding altered expression and the epigenetic state of several target promoters, indicated by histone modifications resulting in transcriptional repression of eight of nine genes investigated here. Furthermore, TRF2 occupancy and target gene expression were also sensitive to the well-known intracellular G-quadruplex-binding ligand 360A. Together, these results reveal an extensive genome-wide association of TRF2 outside telomeres and that it regulates gene expression in a G-quadruplex-dependent fashion.
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Affiliation(s)
- Ananda Kishore Mukherjee
- Integrative and Functional Biology Unit, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Shalu Sharma
- Integrative and Functional Biology Unit, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Sulochana Bagri
- Integrative and Functional Biology Unit, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Rintu Kutum
- Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,G.N.R. Knowledge Centre for Genome Informatics, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,CSIR Ayurgenomics Unit-TRISUTRA, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Pankaj Kumar
- Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,G.N.R. Knowledge Centre for Genome Informatics, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Asgar Hussain
- Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,G.N.R. Knowledge Centre for Genome Informatics, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Prateek Singh
- Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,G.N.R. Knowledge Centre for Genome Informatics, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Dhurjhoti Saha
- Integrative and Functional Biology Unit, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Anirban Kar
- Integrative and Functional Biology Unit, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Debasis Dash
- Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,G.N.R. Knowledge Centre for Genome Informatics, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,CSIR Ayurgenomics Unit-TRISUTRA, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
| | - Shantanu Chowdhury
- Integrative and Functional Biology Unit, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India .,Academy of Scientific and Innovative Research (AcSIR), Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India.,G.N.R. Knowledge Centre for Genome Informatics, Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology (IGIB), Mathura Road, New Delhi 110025, India
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48
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Oxidative Stress: Role and Response of Short Guanine Tracts at Genomic Locations. Int J Mol Sci 2019; 20:ijms20174258. [PMID: 31480304 PMCID: PMC6747389 DOI: 10.3390/ijms20174258] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/20/2019] [Accepted: 07/26/2019] [Indexed: 12/21/2022] Open
Abstract
Over the decades, oxidative stress has emerged as a major concern to biological researchers. It is involved in the pathogenesis of various lifestyle-related diseases such as hypertension, diabetes, atherosclerosis, and neurodegenerative diseases. The connection between oxidative stress and telomere shortening via oxidative guanine lesion is well documented. Telomeres are confined to guanine rich ends of chromosomes. Owing to its self-association properties, it adopts G-quadruplex structures and hampers the overexpression of telomerase in the cancer cells. Guanine, being the most oxidation prone nucleobase, when structured in G-quadruplex entity, is found to respond peculiarly towards oxidative stress. Interestingly, this non-Watson-Crick structural feature exists abundantly in promoters of various oncogenes, exons and other genomic locations. The involvement of G-quadruplex architecture in oncogene promoters is well recognized in gene regulation processes. Development of small molecules aimed to target G-quadruplex structures, have found to alter the overexpression of oncogenes. The interaction may lead to the obstruction of diseased cell having elevated level of reactive oxygen species (ROS). Thus, presence of short guanine tracts (Gn) forming G-quadruplexes suggests its critical role in oxidative genome damage. Present review is a modest attempt to gain insight on the association of oxidative stress and G-quadruplexes, in various biological processes.
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Wumaier M, Shi JJ, Yao TM, Hu XC, Gao RR, Shi S. G-quadruplex and duplex DNA binding studies of novel Ruthenium(II) complexes containing ascididemin ligands. J Inorg Biochem 2019; 196:110681. [DOI: 10.1016/j.jinorgbio.2019.03.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 03/22/2019] [Accepted: 03/27/2019] [Indexed: 11/29/2022]
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50
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Lee YH, Chen YY, Yeh YL, Wang YJ, Chen RJ. Stilbene Compounds Inhibit Tumor Growth by the Induction of Cellular Senescence and the Inhibition of Telomerase Activity. Int J Mol Sci 2019; 20:ijms20112716. [PMID: 31159515 PMCID: PMC6600253 DOI: 10.3390/ijms20112716] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 12/17/2022] Open
Abstract
Cellular senescence is a state of cell cycle arrest characterized by a distinct morphology, gene expression pattern, and secretory phenotype. It can be triggered by multiple mechanisms, including those involved in telomere shortening, the accumulation of DNA damage, epigenetic pathways, and the senescence-associated secretory phenotype (SASP), and so on. In current cancer therapy, cellular senescence has emerged as a potent tumor suppression mechanism that restrains proliferation in cells at risk for malignant transformation. Therefore, compounds that stimulate the growth inhibition effects of senescence while limiting its detrimental effects are believed to have great clinical potential. In this review article, we first review the current knowledge of the pro- and antitumorigeneic functions of senescence and summarize the key roles of telomerase in the regulation of senescence in tumors. Second, we review the current literature regarding the anticancer effects of stilbene compounds that are mediated by the targeting of telomerase and cell senescence. Finally, we provide future perspectives on the clinical utilization of stilbene compounds, especially resveratrol and pterostilbene, as novel cancer therapeutic remedies. We conclude and propose that stilbene compounds may induce senescence and may potentially be used as the therapeutic or adjuvant agents for cancers with high telomerase activity.
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Affiliation(s)
- Yu-Hsuan Lee
- Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan 70428, Taiwan.
| | - Yu-Ying Chen
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan 70428, Taiwan.
| | - Ya-Ling Yeh
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan 70428, Taiwan.
| | - Ying-Jan Wang
- Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan 70428, Taiwan.
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan.
| | - Rong-Jane Chen
- Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan 70428, Taiwan.
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