1
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Pandey A, Roy S, Srivatsan SG. Probing the Competition between Duplex, G-Quadruplex and i-Motif Structures of the Oncogenic c-Myc DNA Promoter Region. Chem Asian J 2023; 18:e202300510. [PMID: 37541298 DOI: 10.1002/asia.202300510] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/09/2023] [Indexed: 08/06/2023]
Abstract
Development of probe systems that provide unique spectral signatures for duplex, G-quadruplex (GQ) and i-motif (iM) structures is very important to understand the relative propensity of a G-rich-C-rich promoter region to form these structures. Here, we devise a platform using a combination of two environment-sensitive nucleoside analogs namely, 5-fluorobenzofuran-modified 2'-deoxyuridine (FBF-dU) and 5-fluoro-2'-deoxyuridine (F-dU) to study the structures adopted by a promoter region of the c-Myc oncogene. FBF-dU serves as a dual-purpose probe containing a fluorescent and 19 F NMR label. When incorporated into the C-rich sequence, it reports the formation of different iMs via changes in its fluorescence properties and 19 F signal. F-dU incorporated into the G-rich ON reports the formation of a GQ structure whose 19 F signal is clearly different from the signals obtained for iMs. Rewardingly, the labeled ONs when mixed with respective complementary strands allows us to determine the relative population of different structures formed by the c-Myc promoter by the virtue of the probe's ability to produce distinct and resolved 19 F signatures for different structures. Our results indicate that at physiological pH and temperature the c-Myc promoter forms duplex, random coil and GQ structures, and does not form an iM. Whereas at acidic pH, the mixture largely forms iM and GQ structures. Taken together, our system will complement existing tools and provide unprecedented insights on the population equilibrium and dynamics of nucleic acid structures under different conditions.
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Affiliation(s)
- Akanksha Pandey
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune, 411008, India
| | - Sarupa Roy
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune, 411008, India
| | - Seergazhi G Srivatsan
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr. Homi Bhabha Road, Pune, 411008, India
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2
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Tsvetkov VB, Turaev AV, Petrunina NA, Melnik DM, Khodarovich YM, Pozmogova GE, Zatsepin TS, Varizhuk AM, Aralov AV. Phenoxazine pseudonucleotides in DNA i-motifs allow precise profiling of small molecule binders by fluorescence monitoring. Analyst 2021; 146:4436-4440. [PMID: 34132709 DOI: 10.1039/d1an00660f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The lack of high throughput screening (HTS) techniques for small molecules that stabilize DNA iMs limits their development as perspective drug candidates. Here we showed that fluorescence monitoring for probing the effects of ligands on the iM stability using the FAM-BHQ1 pair provides incorrect results due to additional dye-related interactions. We developed an alternative system with fluorescent phenoxazine pseudonucleotides in loops that do not alter iM unfolding. At the same time, the fluorescence of phenoxazine residues is sensitive to iM unfolding that enables accurate evaluation of ligand-induced changes of iM stability. Our results provide the basis for new approaches for HTS of iM ligands.
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Affiliation(s)
- Vladimir B Tsvetkov
- Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia and World-Class Research Center "Digital biodesign and personalized healthcare", Sechenov First Moscow State Medical University, 8/2 Trubetskaya Str., Moscow, 119146, Russia and A.V. Topchiev Institute of Petrochemical Synthesis RAS, Moscow, 119071, Russia
| | - Anton V Turaev
- Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Nataliia A Petrunina
- Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia and Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
| | - Denis M Melnik
- Center for Life Sciences, Skolkovo Institute of Science and Technology, Bolshoy boulevard 30b1, Moscow, 121205, Russia
| | - Yuriy M Khodarovich
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
| | - Galina E Pozmogova
- Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Timofei S Zatsepin
- Center for Life Sciences, Skolkovo Institute of Science and Technology, Bolshoy boulevard 30b1, Moscow, 121205, Russia and Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory Str. 1-3, 119992 Moscow, Russia
| | - Anna M Varizhuk
- Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia and Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia and Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Research and Clinical Center of Physical-Chemical Medicine, Moscow 119435, Russia.
| | - Andrey V Aralov
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
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3
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Zhang M, Wei Z, Gong X, Li X, Kang S, Wang J, Liu B, Huang ZS, Li D. Syntheses and evaluation of acridone-naphthalimide derivatives for regulating oncogene PDGFR-β expression. Bioorg Med Chem 2021; 34:116042. [PMID: 33561716 DOI: 10.1016/j.bmc.2021.116042] [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: 11/12/2020] [Revised: 01/12/2021] [Accepted: 01/20/2021] [Indexed: 01/30/2023]
Abstract
Upregulation of platelet-derived growth factor receptor β (PDGFR-β) has been found to be associated with development of various types of cancers, which has become an attractive target for anti-tumor treatment. Previously, we have synthesized and studied an acridone derivative B19, which can selectively bind to and stabilize oncogene c-myc promoter i-motif, resulting in down-regulation of c-myc transcription and translation, however its effect on tumor cells apoptosis requires improvement. In the present study, we synthesized a variety of B19 derivatives containing a known anti-cancer fluorescent chromophore naphthalimide for the purpose of enhancing anti-cancer activity. After screening, we found that acridone-naphthalimide derivative WZZ02 could selectively stabilize PDGFR-β promoter G-quadruplex and destabilize its corresponding i-motif structure, without significant interaction to other oncogenes promoter G-quadruplex and i-motif. WZZ02 down-regulated PDGFR-β gene transcription and translation in a dose-dependent manner, possibly due to above interactions. WZZ02 could significantly inhibit cancer cell proliferation, and induce cell apoptosis and cycle arrest. WZZ02 exhibited tumor growth inhibition activity in MCF-7 xenograft tumor model, which could be due to its binding interactions with PDGFR-β promoter G-quadruplex and i-motif. Our results suggested that WZZ02 as a dual G-quadruplex/i-motif binder could be effective on both oncogene replication and transcription, which could become a promising lead compound for further development with improved potency and selectivity. The wide properties for the derivatives of 1,8-naphthalimide could facilitate further in-depth mechanistic studies of WZZ02 through various fluorescent physical and chemical methods, which could help to further understand the function of PDGFR-β gene promoter G-quadruplex and i-motif.
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Affiliation(s)
- Meiling Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Zuzhuang Wei
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Xue Gong
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Xiaoya Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Shuangshuang Kang
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Jing Wang
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Bobo Liu
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Ding Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road, Guangzhou 510006, PR China.
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4
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Chalikian TV, Liu L, Macgregor RB. Duplex-tetraplex equilibria in guanine- and cytosine-rich DNA. Biophys Chem 2020; 267:106473. [PMID: 33031980 DOI: 10.1016/j.bpc.2020.106473] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/03/2020] [Indexed: 02/07/2023]
Abstract
Noncanonical four-stranded DNA structures, including G-quadruplexes and i-motifs, have been discovered in the cell and are implicated in a variety of genomic regulatory functions. The tendency of a specific guanine- and cytosine-rich region of genomic DNA to adopt a four-stranded conformation depends on its ability to overcome the constraints of duplex base-pairing by undergoing consecutive duplex-to-coil and coil-to-tetraplex transitions. The latter ability is determined by the balance between the free energies of participating ordered and disordered structures. In this review, we present an overview of the literature on the stability of G-quadruplex and i-motif structures and discuss the extent of duplex-tetraplex competition as a function of the sequence context of the DNA and environmental conditions including temperature, pH, salt, molecular crowding, and the presence of G-quadruplex-binding ligands. We outline how the results of in vitro studies can be expanded to understanding duplex-tetraplex equilibria in vivo.
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Affiliation(s)
- Tigran V Chalikian
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
| | - Lutan Liu
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
| | - Robert B Macgregor
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada
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5
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Zhang F, Liu B, Lopez A, Wang S, Liu J. Opposite salt-dependent stability of i-motif and duplex reflected in a single DNA hairpin nanomachine. NANOTECHNOLOGY 2020; 31:195503. [PMID: 31978920 DOI: 10.1088/1361-6528/ab6fdf] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We herein report a DNA hairpin structure containing a polycytosine loop region, and this hairpin can operate like a nanomachine allowing independently controlled stability of the i-motif loop and duplex stem region. This was made possible by the opposite salt-dependent stability of DNA duplex and hairpin, thus providing a new method for designing molecular devices or switches design. A singly-labeled fluorescent method was used to measure the stability of an i-motif DNA in the presence of various metal ions. Salt in general destabilizes the i-motif but stabilizes duplex DNA, allowing us to engineer an i-motif containing hairpin for modulating the stability of each secondary structure independently.
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Affiliation(s)
- Fang Zhang
- College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, People's Republic of China. Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo N2L 3G1, Ontario, Canada
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6
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Tang W, Niu K, Yu G, Jin Y, Zhang X, Peng Y, Chen S, Deng H, Li S, Wang J, Song Q, Feng Q. In vivo visualization of the i-motif DNA secondary structure in the Bombyx mori testis. Epigenetics Chromatin 2020; 13:12. [PMID: 32138783 PMCID: PMC7059380 DOI: 10.1186/s13072-020-00334-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 02/19/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND A large number of in vitro experiments have confirmed that DNA molecules can form i-motif advanced structure when multiple cytosines exist in the sequence. However, whether these structures are present in vivo environment still lacks sufficient experimental evidence. RESULTS In this paper, we report the in vivo visualization of i-motif structures in the nuclei and chromosomes of the testis of the invertebrate Bombyx mori using immunofluorescence staining with an antibody specifically recognizing the endogenous transcription factor BmILF, which binds i-motif structure with high specificity. The number of i-motif structures observed in the genome increased when the pH was changed from basic to acidic and decreased under treatment with an i-motif inhibitor, the porphyrin compound TMPyP4. The pH change affected the transcription of genes that contain i-motif sequences. Moreover, there were more i-motif structures observed in the testis cells in interphase than in any other cell cycle stage. CONCLUSIONS In this study, the i-motif structures in invertebrates were detected for the first time at the cell and organ levels. The formation of the structures depended on cell cycle and pH and affected gene expression.
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Affiliation(s)
- Wenhuan Tang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Kangkang Niu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Guoxing Yu
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Ying Jin
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Xian Zhang
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Yuling Peng
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Shuna Chen
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Huimin Deng
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Sheng Li
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Jian Wang
- Department of Entomology, University of Maryland, College Park, MD, 20742, USA
| | - Qisheng Song
- Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA.
| | - Qili Feng
- Guangdong Provincial Key Laboratory of Insect Developmental Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China. .,Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.
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7
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Paul S, Hossain SS, Samanta A. Insights into the Folding Pathway of a c-MYC-Promoter-Based i-Motif DNA in Crowded Environments at the Single-Molecule Level. J Phys Chem B 2020; 124:763-770. [DOI: 10.1021/acs.jpcb.9b10633] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sneha Paul
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Sk Saddam Hossain
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
| | - Anunay Samanta
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
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8
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Benabou S, Ruckebusch C, Sliwa M, Aviñó A, Eritja R, Gargallo R, de Juan A. Study of conformational transitions of i-motif DNA using time-resolved fluorescence and multivariate analysis methods. Nucleic Acids Res 2020; 47:6590-6605. [PMID: 31199873 PMCID: PMC6649798 DOI: 10.1093/nar/gkz522] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/24/2019] [Accepted: 06/03/2019] [Indexed: 12/27/2022] Open
Abstract
Recently, the presence of i-motif structures at C-rich sequences in human cells and their regulatory functions have been demonstrated. Despite numerous steady-state studies on i-motif at neutral and slightly acidic pH, the number and nature of conformation of this biological structure are still controversial. In this work, the fluorescence lifetime of labelled molecular beacon i-motif-forming DNA sequences at different pH values is studied. The influence of the nature of bases at the lateral loops and the presence of a Watson–Crick-stabilized hairpin are studied by means of time-correlated single-photon counting technique. This allows characterizing the existence of several conformers for which the fluorophore has lifetimes ranging from picosecond to nanosecond. The information on the existence of different i-motif structures at different pH values has been obtained by the combination of classical global decay fitting of fluorescence traces, which provides lifetimes associated with the events defined by the decay of each sequence and multivariate analysis, such as principal component analysis or multivariate curve resolution based on alternating least squares. Multivariate analysis, which is seldom used for this kind of data, was crucial to explore similarities and differences of behaviour amongst the different DNA sequences and to model the presence and identity of the conformations involved in the pH range of interest. The results point that, for i-motif, the intrachain contact formation and its dissociation show lifetimes ten times faster than for the open form of DNA sequences. They also highlight that the presence of more than one i-motif species for certain DNA sequences according to the length of the sequence and the composition of the bases in the lateral loop.
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Affiliation(s)
- Sanae Benabou
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
| | - Cyril Ruckebusch
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Michel Sliwa
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Anna Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Jordi Girona 18-26, E-08034 Barcelona, Spain
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Jordi Girona 18-26, E-08034 Barcelona, Spain
| | - Raimundo Gargallo
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
| | - Anna de Juan
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
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9
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Takahashi S, Sugimoto N. Stability prediction of canonical and non-canonical structures of nucleic acids in various molecular environments and cells. Chem Soc Rev 2020; 49:8439-8468. [DOI: 10.1039/d0cs00594k] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review provides the biophysicochemical background and recent advances in stability prediction of canonical and non-canonical structures of nucleic acids in various molecular environments and cells.
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Affiliation(s)
- Shuntaro Takahashi
- Frontier Institute for Biomolecular Engineering Research (FIBER)
- Konan University
- Kobe
- Japan
| | - Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER)
- Konan University
- Kobe
- Japan
- Graduate School of Frontiers of Innovative Research in Science and Technology (FIRST)
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10
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Chaudhary S, Kaushik M, Ahmed S, Kukreti S. Exploring potential of i-motif DNA formed in the promoter region of GRIN1 gene for nanotechnological applications. RESULTS IN CHEMISTRY 2020. [DOI: 10.1016/j.rechem.2020.100086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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11
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Niu K, Zhang X, Deng H, Wu F, Ren Y, Xiang H, Zheng S, Liu L, Huang L, Zeng B, Li S, Xia Q, Song Q, Palli SR, Feng Q. BmILF and i-motif structure are involved in transcriptional regulation of BmPOUM2 in Bombyx mori. Nucleic Acids Res 2019; 46:1710-1723. [PMID: 29194483 PMCID: PMC5829645 DOI: 10.1093/nar/gkx1207] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 11/23/2017] [Indexed: 12/12/2022] Open
Abstract
Guanine-rich and cytosine-rich DNA can form four-stranded DNA secondary structures called G-quadruplex (G4) and i-motif, respectively. These structures widely exist in genomes and play important roles in transcription, replication, translation and protection of telomeres. In this study, G4 and i-motif structures were identified in the promoter of the transcription factor gene BmPOUM2, which regulates the expression of the wing disc cuticle protein gene (BmWCP4) during metamorphosis. Disruption of the i-motif structure by base mutation, anti-sense oligonucleotides (ASOs) or inhibitory ligands resulted in significant decrease in the activity of the BmPOUM2 promoter. A novel i-motif binding protein (BmILF) was identified by pull-down experiment. BmILF specifically bound to the i-motif and activated the transcription of BmPOUM2. The promoter activity of BmPOUM2 was enhanced when BmILF was over-expressed and decreased when BmILF was knocked-down by RNA interference. This study for the first time demonstrated that BmILF and the i-motif structure participated in the regulation of gene transcription in insect metamorphosis and provides new insights into the molecular mechanism of the secondary structures in epigenetic regulation of gene transcription.
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Affiliation(s)
- Kangkang Niu
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Xiaojuan Zhang
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Huimin Deng
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Feng Wu
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Yandong Ren
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Hui Xiang
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Sichun Zheng
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Lin Liu
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Lihua Huang
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Baojuan Zeng
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Sheng Li
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Qingyou Xia
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Qisheng Song
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Subba Reddy Palli
- Department of Entomology, University of Kentucky, Lexington, KY 40546-0091, USA
| | - Qili Feng
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China
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12
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Shu B, Zeng P, Kang S, Li PH, Hu D, Kuang G, Cao J, Li X, Zhang M, An LK, Huang ZS, Li D. Syntheses and evaluation of new Quinoline derivatives for inhibition of hnRNP K in regulating oncogene c-myc transcription. Bioorg Chem 2018; 85:1-17. [PMID: 30599408 DOI: 10.1016/j.bioorg.2018.12.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 12/22/2022]
Abstract
Aberrant overexpression of heterogeneous nuclear ribonucleoprotein K (hnRNP K) is a key feature in oncogenesis and progression of many human cancers. hnRNP K has been found to be a transcriptional activator to up-regulate c-myc gene transcription, a critical proto-oncogene for regulation of cell growth and differentiation. Therefore, down-regulation of c-myc transcription by inhibiting hnRNP K through disrupting its binding to c-myc gene promoter is a potential approach for cancer therapy. In the present study, we synthesized and screened a series of Quinoline derivatives and evaluated their binding affinity for hnRNP K. Among these derivatives, (E)-1-(4-methoxyphenyl)-3-(4-morpholino-6-nitroquinolin-2-yl)prop-2-en-1-one (compound 25) was determined to be the first-reported hnRNP K binding ligand with its KD values of 4.6 and 2.6 μM measured with SPR and MST, respectively. Subsequent evaluation showed that the binding of compound 25 to hnRNP K could disrupt its unfolding of c-myc promoter i-motif, resulting in down-regulation of c-myc transcription. Compound 25 showed a selective anti-proliferative effect on human cancer cell lines with IC50 values ranged from 1.36 to 3.59 μM. Compound 25 exhibited good tumor growth inhibition in a Hela xenograft tumor model, which might be related to its binding with hnRNP K. These findings illustrated that inhibition of DNA-binding protein hnRNP K by compound 25 could be a new and selective strategy of regulating oncogene transcription instead of targeting promoter DNA secondary structures such as G-quadruplexes or i-motifs.
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Affiliation(s)
- Bing Shu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China; School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006, PR China
| | - Ping Zeng
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Shuangshuang Kang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Peng-Hui Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Dexuan Hu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Guotao Kuang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Jiaojiao Cao
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Xiaoya Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Meiling Zhang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Lin-Kun An
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Ding Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China.
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13
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Protopopova AD, Tsvetkov VB, Varizhuk AM, Barinov NA, Podgorsky VV, Klinov DV, Pozmogova GE. The structural diversity of C-rich DNA aggregates: unusual self-assembly of beetle-like nanostructures. Phys Chem Chem Phys 2018; 20:3543-3553. [PMID: 29336444 DOI: 10.1039/c7cp05380k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We studied the ability of oligonucleotides CnT25 (n = 2, 5, 7, 9, 12, 25) to form an intermolecular i-motif using circular dichroism, ultra-violet spectroscopy, nuclear magnetic resonance, high-resolution atomic force microscopy, high-performance liquid chromatography, and molecular dynamics simulations. The arrangement of single-stranded oligonucleotides in multimer i-motifs was very unusual: C-tracts of different oligonucleotides followed each other consecutively in order to fold into a closed intermolecular i-motif core with minimal loops (one cytidine in a loop spanning over a minor groove, three cytidines in a loop over a major groove); intact T-tracts protruded from predefined loci allowing visualization of beetle-like nanostructures by atomic force microscopy. The same structures were formed from analogous biotinylated oligonucleotides demonstrating one of the potential applications of such structures as carriers of multiple functional groups. Our findings open up possibilities for the rational design of pH-sensitive DNA aggregates and evaluation of the efficiency of their assembly.
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Affiliation(s)
- A D Protopopova
- Biophysics Department, Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, 119435, Russia.
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14
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Liu L, Kim BG, Feroze U, Macgregor RB, Chalikian TV. Probing the Ionic Atmosphere and Hydration of the c-MYC i-Motif. J Am Chem Soc 2018; 140:2229-2238. [DOI: 10.1021/jacs.7b11537] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lutan Liu
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
| | - Byul G. Kim
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
| | - Ujala Feroze
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
| | - Robert B. Macgregor
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
| | - Tigran V. Chalikian
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
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15
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Saxena S, Joshi S, Shankaraswamy J, Tyagi S, Kukreti S. Magnesium and molecular crowding of the cosolutes stabilize the i-motif structure at physiological pH. Biopolymers 2018; 107. [PMID: 28295161 DOI: 10.1002/bip.23018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 03/06/2017] [Accepted: 03/06/2017] [Indexed: 11/09/2022]
Abstract
Most of the important genomic regions, especially the G,C rich gene promoters, consist of sequences with potential to form G,C-tetraplexes on both the DNA strands. In this study, we used three C-rich oligonucleotides (11Py, 21Py, and HTPy), of which 11Py and 21Py are located at various transcriptional regulatory elements of the human genome while HTPy sequence is a C-rich strand of human telomere sequence. These C-rich oligonucleotides formed i-motif structures, verified by Circular Dichroism (CD), UV absorption melting experiments, and native gel electrophoresis. The CD spectra revealed that 11Py and 21Py form i-motif structures at acidic pH values of 4.5 and 5.7 in the presence of 100 mM NaCl but remain unstructured at pH 7.0. However, 21Py can form stable i-motif structure even at neutral pH in presence of 1 mM MgCl2 . UV-thermal melting studies showed stabilization of 21Py i-motif at pH 5.7 in the presence of Na+ or K+ with increasing concentration of MgCl2 or CaCl2 from 1 to 10 mM. Significant shift in the CD peak of HTPy sequence was observed as the positive peak from 286 nm shifted to 276 nm while the negative peak from 265 to 254 nm. Further, inevitable necessity of 1 mM Mg2+ to form i-motif structure at neutral pH was observed. Under similar ionic conditions and neutral pH, all the three C-rich sequences were able to form stable i-motif structures (11Py, 21Py) or altered i-motif/homoduplex structures (HTPy) in the presence of MgCl2 and cell mimicking molecular crowding conditions of 40 wt% PEG 200. It is concluded that presence of Mg2+ ions and molecular crowding agents induce and stabilize i-motif structures at physiological solution environment.
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Affiliation(s)
- Sarika Saxena
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, 201313, India
| | - Savita Joshi
- Department of Chemistry, Nucleic Acids Research laboratory, University of Delhi (North Campus), Delhi, 110007, India
| | - J Shankaraswamy
- Amity International Centre for Post Harvest Technology and Cold Chain Management, Amity University Uttar Pradesh, Noida, 201313, India
| | - Shikhar Tyagi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, 201313, India
| | - Shrikant Kukreti
- Department of Chemistry, Nucleic Acids Research laboratory, University of Delhi (North Campus), Delhi, 110007, India
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16
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Benabou S, Aviñó A, Lyonnais S, González C, Eritja R, De Juan A, Gargallo R. i-motif structures in long cytosine-rich sequences found upstream of the promoter region of the SMARCA4 gene. Biochimie 2017; 140:20-33. [DOI: 10.1016/j.biochi.2017.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 06/06/2017] [Indexed: 12/27/2022]
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17
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Kshirsagar R, Khan K, Joshi MV, Hosur RV, Muniyappa K. Probing the Potential Role of Non-B DNA Structures at Yeast Meiosis-Specific DNA Double-Strand Breaks. Biophys J 2017; 112:2056-2074. [PMID: 28538144 DOI: 10.1016/j.bpj.2017.04.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 04/13/2017] [Accepted: 04/19/2017] [Indexed: 12/29/2022] Open
Abstract
A plethora of evidence suggests that different types of DNA quadruplexes are widely present in the genome of all organisms. The existence of a growing number of proteins that selectively bind and/or process these structures underscores their biological relevance. Moreover, G-quadruplex DNA has been implicated in the alignment of four sister chromatids by forming parallel guanine quadruplexes during meiosis; however, the underlying mechanism is not well defined. Here we show that a G/C-rich motif associated with a meiosis-specific DNA double-strand break (DSB) in Saccharomyces cerevisiae folds into G-quadruplex, and the C-rich sequence complementary to the G-rich sequence forms an i-motif. The presence of G-quadruplex or i-motif structures upstream of the green fluorescent protein-coding sequence markedly reduces the levels of gfp mRNA expression in S. cerevisiae cells, with a concomitant decrease in green fluorescent protein abundance, and blocks primer extension by DNA polymerase, thereby demonstrating the functional significance of these structures. Surprisingly, although S. cerevisiae Hop1, a component of synaptonemal complex axial/lateral elements, exhibits strong affinity to G-quadruplex DNA, it displays a much weaker affinity for the i-motif structure. However, the Hop1 C-terminal but not the N-terminal domain possesses strong i-motif binding activity, implying that the C-terminal domain has a distinct substrate specificity. Additionally, we found that Hop1 promotes intermolecular pairing between G/C-rich DNA segments associated with a meiosis-specific DSB site. Our results support the idea that the G/C-rich motifs associated with meiosis-specific DSBs fold into intramolecular G-quadruplex and i-motif structures, both in vitro and in vivo, thus revealing an important link between non-B form DNA structures and Hop1 in meiotic chromosome synapsis and recombination.
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Affiliation(s)
- Rucha Kshirsagar
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Krishnendu Khan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Mamata V Joshi
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Ramakrishna V Hosur
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - K Muniyappa
- Department of Biochemistry, Indian Institute of Science, Bangalore, India.
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18
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Brown RV, Wang T, Chappeta VR, Wu G, Onel B, Chawla R, Quijada H, Camp SM, Chiang ET, Lassiter QR, Lee C, Phanse S, Turnidge MA, Zhao P, Garcia JGN, Gokhale V, Yang D, Hurley LH. The Consequences of Overlapping G-Quadruplexes and i-Motifs in the Platelet-Derived Growth Factor Receptor β Core Promoter Nuclease Hypersensitive Element Can Explain the Unexpected Effects of Mutations and Provide Opportunities for Selective Targeting of Both Structures by Small Molecules To Downregulate Gene Expression. J Am Chem Soc 2017; 139:7456-7475. [PMID: 28471683 PMCID: PMC5977998 DOI: 10.1021/jacs.6b10028] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The platelet-derived growth factor receptor β (PDGFR-β) signaling pathway is a validated and important target for the treatment of certain malignant and nonmalignant pathologies. We previously identified a G-quadruplex-forming nuclease hypersensitive element (NHE) in the human PDGFR-β promoter that putatively forms four overlapping G-quadruplexes. Therefore, we further investigated the structures and biological roles of the G-quadruplexes and i-motifs in the PDGFR-β NHE with the ultimate goal of demonstrating an alternate and effective strategy for molecularly targeting the PDGFR-β pathway. Significantly, we show that the primary G-quadruplex receptor for repression of PDGFR-β is the 3'-end G-quadruplex, which has a GGA sequence at the 3'-end. Mutation studies using luciferase reporter plasmids highlight a novel set of G-quadruplex point mutations, some of which seem to provide conflicting results on effects on gene expression, prompting further investigation into the effect of these mutations on the i-motif-forming strand. Herein we characterize the formation of an equilibrium between at least two different i-motifs from the cytosine-rich (C-rich) sequence of the PDGFR-β NHE. The apparently conflicting mutation results can be rationalized if we take into account the single base point mutation made in a critical cytosine run in the PDGFR-β NHE that dramatically affects the equilibrium of i-motifs formed from this sequence. We identified a group of ellipticines that targets the G-quadruplexes in the PDGFR-β promoter, and from this series of compounds, we selected the ellipticine analog GSA1129, which selectively targets the 3'-end G-quadruplex, to shift the dynamic equilibrium in the full-length sequence to favor this structure. We also identified a benzothiophene-2-carboxamide (NSC309874) as a PDGFR-β i-motif-interactive compound. In vitro, GSA1129 and NSC309874 downregulate PDGFR-β promoter activity and transcript in the neuroblastoma cell line SK-N-SH at subcytotoxic cell concentrations. GSA1129 also inhibits PDGFR-β-driven cell proliferation and migration. With an established preclinical murine model of acute lung injury, we demonstrate that GSA1129 attenuates endotoxin-mediated acute lung inflammation. Our studies underscore the importance of considering the effects of point mutations on structure formation from the G- and C-rich sequences and provide further evidence for the involvement of both strands and associated structures in the control of gene expression.
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Affiliation(s)
- Robert V. Brown
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Ting Wang
- College of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, Arizona 85724, United States
| | | | - Guanhui Wu
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Buket Onel
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
| | - Reena Chawla
- BIO5 Institute, 1657 East Helen Street, Tucson, Arizona 85721, United States
| | - Hector Quijada
- College of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, Arizona 85724, United States
| | - Sara M. Camp
- College of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, Arizona 85724, United States
| | - Eddie T. Chiang
- College of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, Arizona 85724, United States
| | - Quinea R. Lassiter
- College of Agriculture & Life Sciences, University of Arizona, 1117 East Lowell Street, Tucson, Arizona 85721, United States
| | - Carmen Lee
- College of Agriculture & Life Sciences, University of Arizona, 1117 East Lowell Street, Tucson, Arizona 85721, United States
- College of Science, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, United States
| | - Shivani Phanse
- College of Science, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, United States
| | - Megan A. Turnidge
- College of Science, University of Arizona, 1040 East Fourth Street, Tucson, Arizona 85721, United States
| | - Ping Zhao
- School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, No. 280 Waihuandong Road, Education Mega Centre, Guanzhou 510006, Peoples Republic of China
| | - Joe G. N. Garcia
- College of Medicine, University of Arizona, 1501 North Campbell Avenue, Tucson, Arizona 85724, United States
| | - Vijay Gokhale
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
- BIO5 Institute, 1657 East Helen Street, Tucson, Arizona 85721, United States
| | - Danzhou Yang
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
- BIO5 Institute, 1657 East Helen Street, Tucson, Arizona 85721, United States
- University of Arizona Cancer Center, 1515 North Campbell Avenue, Tucson, Arizona 85724, United States
| | - Laurence H. Hurley
- College of Pharmacy, University of Arizona, 1703 East Mabel Street, Tucson, Arizona 85721, United States
- BIO5 Institute, 1657 East Helen Street, Tucson, Arizona 85721, United States
- University of Arizona Cancer Center, 1515 North Campbell Avenue, Tucson, Arizona 85724, United States
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19
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Kim BG, Chalikian TV. Thermodynamic linkage analysis of pH-induced folding and unfolding transitions of i-motifs. Biophys Chem 2016; 216:19-22. [DOI: 10.1016/j.bpc.2016.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 06/09/2016] [Accepted: 06/09/2016] [Indexed: 10/21/2022]
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20
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Fujii T, Sugimoto N. Loop nucleotides impact the stability of intrastrand i-motif structures at neutral pH. Phys Chem Chem Phys 2016; 17:16719-22. [PMID: 26058487 DOI: 10.1039/c5cp02794b] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The stability of i-motif structures at neutral pH is of interest due to the potential of these structures to impact gene expression. A systematic investigation of loop sequence and length revealed that certain loop nucleobases stabilize i-motif quadruplexes.
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Affiliation(s)
- Taiga Fujii
- Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University, 8-9-1 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan.
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21
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Abstract
Fluorescent silver nanoclusters (Ag-NCs) are in prominence as novel sensing materials due to their biocompatibility, photostability, and molecule-like optical properties. The present work is carried out on an array (17 sequences) of 16 bases long cytosine rich, single stranded DNA templates 5′-C3XiC3XiiC3XiiiC3Xiv-3′ where i, ii, iii, iv correspond to T/G/C deoxynucleobases (with default base A). Among all the oligonucleotides, a sequence C3AC3AC3TC3G (3T4G) has been identified, which grows three different near-infrared-emitting NC species with absorption/emission maxima at ~620/700 (species I), 730/800 (species II), and 830 (Species III) nm, respectively. The nature of the spectral profiles, along with relevant parameters namely absorption maximum (λabsmax), emission maximum (λemmax), anisotropy (r), lifetime (τ), circular dichroism spectral data are used to understand the microenvironments of the fluorescent NC species I, II, and III. DNA:Ag stiochiometric, pH and solvent dependent studies proved that i-motif scaffolds with different folding topologies are associated with the growth of these three species and a certain concentration of silver and H+ favor the growth of species III. Size exclusion chromatographic measurements provided similar indications that a folded, more compact, classic i-motif template is associated with the formation of the longer NIR (~830 nm) absorbing species. This study provides a more definitive approach to design and obtain a targeted DNA templated Ag-NC with required emission properties for biophysical and cellular applications.
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Affiliation(s)
- Bidisha Sengupta
- Department of Chemistry, Tougaloo College, 500 West County Line Road, Tougaloo, MS 39174, USA; (C.C.); (K.C.); (A.S.)
- Correspondence: ; Tel.: +1-601-977-7779; Fax: +1-601-977-7898
| | - Christa Corley
- Department of Chemistry, Tougaloo College, 500 West County Line Road, Tougaloo, MS 39174, USA; (C.C.); (K.C.); (A.S.)
| | - Keith Cobb
- Department of Chemistry, Tougaloo College, 500 West County Line Road, Tougaloo, MS 39174, USA; (C.C.); (K.C.); (A.S.)
| | - Anthony Saracino
- Department of Chemistry, Tougaloo College, 500 West County Line Road, Tougaloo, MS 39174, USA; (C.C.); (K.C.); (A.S.)
| | - Steffen Jockusch
- Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA;
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22
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Li T, He N, Wang J, Li S, Deng Y, Wang Z. Effects of the i-motif DNA loop on the fluorescence of silver nanoclusters. RSC Adv 2016. [DOI: 10.1039/c5ra22489f] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The loop sequences in i-motif DNA templates are well correlated with the fluorescence of the prepared Ag clusters.
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Affiliation(s)
- Taotao Li
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- China
| | - Nongyue He
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- China
| | - Jiuhai Wang
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- China
| | - Song Li
- Economical Forest Cultivation and Utilization of 2011 Collaborative Innovation Center in Hunan Province
- Hunan Key Laboratory of Green Packaging and Biological Nanotechnology
- Hunan University of Technology
- Zhuzhou 412007
- China
| | - Yan Deng
- Economical Forest Cultivation and Utilization of 2011 Collaborative Innovation Center in Hunan Province
- Hunan Key Laboratory of Green Packaging and Biological Nanotechnology
- Hunan University of Technology
- Zhuzhou 412007
- China
| | - Zunliang Wang
- State Key Laboratory of Bioelectronics
- School of Biological Science and Medical Engineering
- Southeast University
- Nanjing 210096
- China
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23
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Garavís M, Méndez-Lago M, Gabelica V, Whitehead SL, González C, Villasante A. The structure of an endogenous Drosophila centromere reveals the prevalence of tandemly repeated sequences able to form i-motifs. Sci Rep 2015; 5:13307. [PMID: 26289671 PMCID: PMC4542561 DOI: 10.1038/srep13307] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 07/21/2015] [Indexed: 12/21/2022] Open
Abstract
Centromeres are the chromosomal loci at which spindle microtubules attach to mediate chromosome segregation during mitosis and meiosis. In most eukaryotes, centromeres are made up of highly repetitive DNA sequences (satellite DNA) interspersed with middle repetitive DNA sequences (transposable elements). Despite the efforts to establish complete genomic sequences of eukaryotic organisms, the so-called 'finished' genomes are not actually complete because the centromeres have not been assembled due to the intrinsic difficulties in constructing both physical maps and complete sequence assemblies of long stretches of tandemly repetitive DNA. Here we show the first molecular structure of an endogenous Drosophila centromere and the ability of the C-rich dodeca satellite strand to form dimeric i-motifs. The finding of i-motif structures in simple and complex centromeric satellite DNAs leads us to suggest that these centromeric sequences may have been selected not by their primary sequence but by their ability to form noncanonical secondary structures.
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Affiliation(s)
- Miguel Garavís
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain.,Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | - María Méndez-Lago
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
| | - Valérie Gabelica
- Univ. Bordeaux, ARNA Laboratory, IECB, 2 rue Robert Escarpit, F-33600 Pessac, France.,Inserm ARNA Laboratory, 146 rue Leo Saignat, F-33000 Bordeaux, France
| | - Siobhan L Whitehead
- The Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | - Carlos González
- Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Alfredo Villasante
- Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Nicolás Cabrera 1, 28049 Madrid, Spain
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24
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Greco ML, Folini M, Sissi C. Double stranded promoter region of BRAF undergoes to structural rearrangement in nearly physiological conditions. FEBS Lett 2015; 589:2117-23. [DOI: 10.1016/j.febslet.2015.06.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 06/10/2015] [Accepted: 06/19/2015] [Indexed: 10/23/2022]
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25
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Lannes L, Halder S, Krishnan Y, Schwalbe H. Tuning the pH Response of i-Motif DNA Oligonucleotides. Chembiochem 2015; 16:1647-56. [PMID: 26032298 DOI: 10.1002/cbic.201500182] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 12/19/2022]
Abstract
Cytosine-rich single-stranded DNA oligonucleotides are able to adopt an i-motif conformation, a four-stranded structure, near a pH of 6. This unique pH-dependent conformational switch is reversible and hence can be controlled by changing the pH. Here, we show that the pH response range of the human telomeric i-motif can be shifted towards more basic pH values by introducing 5-methylcytidines (5-MeC) and towards more acidic pH values by introducing 5-bromocytidines (5-BrC). No thermal destabilisation was observed in these chemically modified i-motif sequences. The time required to attain the new conformation in response to sudden pH changes was slow for all investigated sequences but was found to be ten times faster in the 5-BrC derivative of the i-motif.
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Affiliation(s)
- Laurie Lannes
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main (Germany)
| | - Saheli Halder
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 560065 (India)
| | - Yamuna Krishnan
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 560065 (India).,Department of Chemistry, University of Chicago, E305, GCIS, 929 E, 57th Street, Chicago, IL 60637 (USA)
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt/Main (Germany).
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26
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Mata G, Luedtke NW. Fluorescent Probe for Proton-Coupled DNA Folding Revealing Slow Exchange of i-Motif and Duplex Structures. J Am Chem Soc 2015; 137:699-707. [DOI: 10.1021/ja508741u] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Guillaume Mata
- Department of Chemistry, University of Zürich, Winterthurerstrasse
190, CH-8057 Zürich, Switzerland
| | - Nathan W. Luedtke
- Department of Chemistry, University of Zürich, Winterthurerstrasse
190, CH-8057 Zürich, Switzerland
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27
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Regulation of tyrosine hydroxylase transcription by hnRNP K and DNA secondary structure. Nat Commun 2014; 5:5769. [PMID: 25493445 PMCID: PMC4264680 DOI: 10.1038/ncomms6769] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 11/04/2014] [Indexed: 12/29/2022] Open
Abstract
Regulation of tyrosine hydroxylase gene (Th) transcription is critical for specifying and maintaining the dopaminergic neuronal phenotype. Here we define a molecular regulatory mechanism for Th transcription conserved in tetrapod vertebrates. We show that heterogeneous nuclear ribonucleoprotein (hnRNP) K is a transactivator of Th transcription. It binds to previously unreported and evolutionarily conserved G:C-rich regions in the Th proximal promoter. hnRNP K directly binds C-rich single DNA strands within these conserved regions and also associates with double-stranded sequences when proteins, such as CREB, are bound to an adjacent cis-regulatory element. The single DNA strands within the conserved G:C-rich regions adopt either G-quadruplex or i-motif secondary structures. We also show that small molecule-mediated stabilization of these secondary structures represses Th promoter activity. These data suggest that these secondary structures are targets for pharmacological modulation of the dopaminergic phenotype.
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28
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Amato J, Iaccarino N, Randazzo A, Novellino E, Pagano B. Noncanonical DNA Secondary Structures as Drug Targets: the Prospect of the i-Motif. ChemMedChem 2014; 9:2026-30. [DOI: 10.1002/cmdc.201402153] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Indexed: 11/06/2022]
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29
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Kendrick S, Kang HJ, Alam MP, Madathil MM, Agrawal P, Gokhale V, Yang D, Hecht SM, Hurley LH. The dynamic character of the BCL2 promoter i-motif provides a mechanism for modulation of gene expression by compounds that bind selectively to the alternative DNA hairpin structure. J Am Chem Soc 2014; 136:4161-71. [PMID: 24559410 PMCID: PMC3985915 DOI: 10.1021/ja410934b] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
It
is generally accepted that DNA predominantly exists in duplex
form in cells. However, under torsional stress imposed by active transcription,
DNA can assume nonduplex structures. The BCL2 promoter
region forms two different secondary DNA structures on opposite strands
called the G-quadruplex and the i-motif. The i-motif is a highly dynamic
structure that exists in equilibrium with a flexible hairpin species.
Here we identify a pregnanol derivative and a class of piperidine
derivatives that differentially modulate gene expression by stabilizing
either the i-motif or the flexible hairpin species. Stabilization
of the i-motif structure results in significant upregulation of the BCL2 gene and associated protein expression; in contrast,
stabilization of the flexible hairpin species lowers BCL2 levels. The BCL2 levels reduced by the hairpin-binding
compound led to chemosensitization to etoposide in both in vitro and
in vivo models. Furthermore, we show antagonism between the two classes
of compounds in solution and in cells. For the first time, our results
demonstrate the principle of small molecule targeting of i-motif structures
in vitro and in vivo to modulate gene expression.
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Affiliation(s)
- Samantha Kendrick
- Arizona Cancer Center, University of Arizona , Tucson, Arizona 85724, United States
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30
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Benabou S, Aviñó A, Eritja R, González C, Gargallo R. Fundamental aspects of the nucleic acid i-motif structures. RSC Adv 2014. [DOI: 10.1039/c4ra02129k] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The latest research on fundamental aspects of i-motif structures is reviewed with special attention to their hypothetical rolein vivo.
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Affiliation(s)
- S. Benabou
- Department of Analytical Chemistry
- University of Barcelona
- E-08028 Barcelona, Spain
| | - A. Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC)
- CIBER-BBN Networking Centre on Bioengineering
- Biomaterials and Nanomedicine
- E-08034 Barcelona, Spain
| | - R. Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC-CSIC)
- CIBER-BBN Networking Centre on Bioengineering
- Biomaterials and Nanomedicine
- E-08034 Barcelona, Spain
| | - C. González
- Institute of Physical Chemistry “Rocasolano”
- CSIC
- E-28006 Madrid, Spain
| | - R. Gargallo
- Department of Analytical Chemistry
- University of Barcelona
- E-08028 Barcelona, Spain
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31
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Cui J, Waltman P, Le VH, Lewis EA. The effect of molecular crowding on the stability of human c-MYC promoter sequence I-motif at neutral pH. Molecules 2013; 18:12751-67. [PMID: 24132198 PMCID: PMC6270392 DOI: 10.3390/molecules181012751] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 09/26/2013] [Accepted: 10/10/2013] [Indexed: 12/20/2022] Open
Abstract
We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). In terms of drug targeting, the question is whether c-MYC promoter sequence i-motifs will exist in the nucleus at neutral pH. In this work, we have investigated the stability of a mutant c-MYC i-motif in solutions containing a molecular crowding agent. The crowded nuclear environment was modeled by the addition of up to 40% w/w polyethylene glycols having molecular weights up to 12,000 g/mol. CD and DSC were used to establish the presence and stability of c-MYC i-motifs in buffer solutions over the pH range 4 to 7. We have shown that the c-MYC i-motif can exist as a stable structure at pH values as high as 6.7 in crowded solutions. Generic dielectric constant effects, e.g., a shift in the pKa of cytosine by more than 2 units (e.g., 4.8 to 7.0), or the formation of non-specific PEG/DNA complexes appear to contribute insignificantly to i-motif stabilization. Molecular crowding, largely an excluded volume effect of added PEG, having a molecular weight in excess of 1,000 g/mol, appears to be responsible for stabilizing the more compact i-motif over the random coil at higher pH values.
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Affiliation(s)
- Jingjing Cui
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA.
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32
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Le VH, Nagesh N, Lewis EA. Bcl-2 promoter sequence G-quadruplex interactions with three planar and non-planar cationic porphyrins: TMPyP4, TMPyP3, and TMPyP2. PLoS One 2013; 8:e72462. [PMID: 23977303 PMCID: PMC3748076 DOI: 10.1371/journal.pone.0072462] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 07/18/2013] [Indexed: 12/31/2022] Open
Abstract
The interactions of three related cationic porphyrins, TMPyP4, TMPyP3 and TMPyP2, with a WT 39-mer Bcl-2 promoter sequence G-quadruplex were studied using Circular Dichroism, ESI mass spectrometry, Isothermal Titration Calorimetry, and Fluorescence spectroscopy. The planar cationic porphyrin TMPyP4 (5, 10, 15, 20-meso-tetra (N-methyl-4-pyridyl) porphine) is shown to bind to a WT Bcl-2 G-quadruplex via two different binding modes, an end binding mode and a weaker mode attributed to intercalation. The related non-planar ligands, TMPyP3 and TMPyP2, are shown to bind to the Bcl-2 G-quadruplex by a single mode. ESI mass spectrometry experiments confirmed that the saturation stoichiometry is 4:1 for the TMPyP4 complex and 2:1 for the TMPyP2 and TMPyP3 complexes. ITC experiments determined that the equilibrium constant for formation of the (TMPyP4)1/DNA complex (K1 = 3.7 × 10(6)) is approximately two orders of magnitude greater than the equilibrium constant for the formation of the (TMPyP2)1/DNA complex, (K1 = 7.0 × 10(4)). Porphyrin fluorescence is consistent with intercalation in the case of the (TMPyP4)3/DNA and (TMPyP4)4/DNA complexes. The non-planar shape of the TMPyP2 and TMPyP3 molecules results in both a reduced affinity for the end binding interaction and the elimination of the intercalation binding mode.
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Affiliation(s)
- Vu H. Le
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, United States of America
| | - Narayana Nagesh
- Centre for Cellular and Molecular Biology, Hyderabad, Andhra Pradesh, India
| | - Edwin A. Lewis
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, United States of America
- * E-mail:
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33
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Choi J, Majima T. Reversible conformational switching of i-motif DNA studied by fluorescence spectroscopy. Photochem Photobiol 2013; 89:513-22. [PMID: 23311444 DOI: 10.1111/php.12042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 01/04/2013] [Indexed: 12/19/2022]
Abstract
Non-B DNAs, which can form unique structures other than double helix of B-DNA, have attracted considerable attention from scientists in various fields including biology, chemistry and physics etc. Among them, i-motif DNA, which is formed from cytosine (C)-rich sequences found in telomeric DNA and the promoter region of oncogenes, has been extensively investigated as a signpost and controller for the oncogene expression at the transcription level and as a promising material in nanotechnology. Fluorescence techniques such as fluorescence resonance energy transfer (FRET) and the fluorescence quenching are important for studying DNA and in particular for the visualization of reversible conformational switching of i-motif DNA that is triggered by the protonation. Here, we review the latest studies on the conformational dynamics of i-motif DNA as well as the application of FRET and fluorescence quenching techniques to the visualization of reversible conformational switching of i-motif DNA in nano-biotechnology.
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Affiliation(s)
- Jungkweon Choi
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Osaka, Japan
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34
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Choi J, Kim S, Tachikawa T, Fujitsuka M, Majima T. pH-Induced Intramolecular Folding Dynamics of i-Motif DNA. J Am Chem Soc 2011; 133:16146-53. [DOI: 10.1021/ja2061984] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jungkweon Choi
- The Institute of Scientific and Industrial (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 Japan
| | - Sooyeon Kim
- The Institute of Scientific and Industrial (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 Japan
| | - Takashi Tachikawa
- The Institute of Scientific and Industrial (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 Japan
| | - Mamoru Fujitsuka
- The Institute of Scientific and Industrial (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 Japan
| | - Tetsuro Majima
- The Institute of Scientific and Industrial (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047 Japan
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35
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Abstract
In contrast to B-DNA that has a right-handed double helical structure with Watson-Crick base pairing under the ordinary physiological conditions, repetitive DNA sequences under certain conditions have the potential to fold into non-B DNA structures such as hairpin, triplex, cruciform, left-handed Z-form, tetraplex, A-motif, etc. Since the non-B DNA-forming sequences induce the genetic instability and consequently can cause human diseases, the molecular mechanism for their genetic instability has been extensively investigated. On the contrary, non-B DNA can be widely used for application in biotechnology because many DNA breakage hotspots are mapped in or near the sequences that have the potential to adopt non-B DNA structures. In addition, they are regarded as a fascinating material for the nanotechnology using non-B DNAs because they do not produce any toxic byproducts and are robust enough for the repetitive working cycle. This being the case, an understanding on the mechanism and dynamics of their structural changes is important. In this critical review, we describe the latest studies on the conformational dynamics of non-B DNAs, with a focus on G-quadruplex, i-motif, Z-DNA, A-motif, hairpin and triplex (189 references).
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Affiliation(s)
- Jungkweon Choi
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Ibaraki, Osaka 567-0047, Japan
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36
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Dettler JM, Buscaglia R, Le VH, Lewis EA. DSC deconvolution of the structural complexity of c-MYC P1 promoter G-quadruplexes. Biophys J 2011; 100:1517-25. [PMID: 21402034 DOI: 10.1016/j.bpj.2011.01.068] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 01/21/2011] [Accepted: 01/25/2011] [Indexed: 01/01/2023] Open
Abstract
We completed a biophysical characterization of the c-MYC proto-oncogene P1 promoter quadruplex and its interaction with a cationic porphyrin, 5,10,15,20-tetra(N-methyl-4-pyridyl)porphyrin (TMPyP4), using differential scanning calorimetry, isothermal titration calorimetry, and circular dichroism spectroscopy. We examined three different 24-mer oligonucleotides, including the wild-type (WT) sequence found in the c-MYC P(1) promoter and two mutant G→T sequences that are known to fold into single 1:2:1 and 1:6:1 loop isomer quadruplexes. Biophysical experiments were performed on all three oligonucleotide sequences at two different ionic strengths (30 mM [K(+)] and 130 mM [K(+)]). Differential scanning calorimetry experiments demonstrated that the WT quadruplex consists of a mixture of at least two different folded conformers at both ionic strengths, whereas both mutant sequences exhibit a single two-state melting transition at both ionic strengths. Isothermal titration calorimetry experiments demonstrated that both mutant sequences bind 4 mols of TMPyP4 to 1 mol of DNA, in similarity to the WT sequence. The circular dichroism spectroscopy signatures for all three oligonucleotides at both ionic strengths are consistent with an intramolecular parallel stranded G-quadruplex structure, and no change in quadruplex structure is observed upon addition of saturating amounts of TMPyP4 (i.e., 4:1 TMPyP4/DNA).
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Affiliation(s)
- Jamie M Dettler
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi, USA
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