1
|
Ylagan M, Xu Q, Kowalski J. TTSBBC: triplex target site biomarkers and barcodes in cancer. Nucleic Acids Res 2024; 52:W547-W555. [PMID: 38661214 PMCID: PMC11223863 DOI: 10.1093/nar/gkae312] [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: 02/03/2024] [Revised: 03/28/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024] Open
Abstract
The technology of triplex-forming oligonucleotides (TFOs) provides an approach to manipulate genes at the DNA level. TFOs bind to specific sites on genomic DNA, creating a unique intermolecular triple-helix DNA structure through Hoogsteen hydrogen bonding. This targeting by TFOs is site-specific and the locations TFOs bind are referred to as TFO target sites (TTS). Triplexes have been observed to selectively influence gene expression, homologous recombination, mutations, protein binding, and DNA damage. These sites typically feature a poly-purine sequence in duplex DNA, and the characteristics of these TTS sequences greatly influence the formation of the triplex. We introduce TTSBBC, a novel analysis and visualization platform designed to explore features of TTS sequences to enable users to design and validate TTSs. The web server can be freely accessed at https://kowalski-labapps.dellmed.utexas.edu/TTSBBC/.
Collapse
Affiliation(s)
- Maya Ylagan
- Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, TX78712, USA
| | - Qi Xu
- Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, TX78712, USA
| | - Jeanne Kowalski
- Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, TX78712, USA
| |
Collapse
|
2
|
Garavís M, Edwards PJB, Serrano-Chacón I, Doluca O, Filichev V, González C. Understanding intercalative modulation of G-rich sequence folding: solution structure of a TINA-conjugated antiparallel DNA triplex. Nucleic Acids Res 2024; 52:2686-2697. [PMID: 38281138 PMCID: PMC10954471 DOI: 10.1093/nar/gkae028] [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: 06/22/2023] [Revised: 12/21/2023] [Accepted: 01/06/2024] [Indexed: 01/30/2024] Open
Abstract
We present here the high-resolution structure of an antiparallel DNA triplex in which a monomer of para-twisted intercalating nucleic acid (para-TINA: (R)-1-O-[4-(1-pyrenylethynyl)phenylmethyl]glycerol) is covalently inserted as a bulge in the third strand of the triplex. TINA is a potent modulator of the hybridization properties of DNA sequences with extremely useful properties when conjugated in G-rich oligonucleotides. The insertion of para-TINA between two guanines of the triplex imparts a high thermal stabilization (ΔTM = 9ºC) to the structure and enhances the quality of NMR spectra by increasing the chemical shift dispersion of proton signals near the TINA location. The structural determination reveals that TINA intercalates between two consecutive triads, causing only local distortions in the structure. The two aromatic moieties of TINA are nearly coplanar, with the phenyl ring intercalating between the flanking guanine bases in the sequence, and the pyrene moiety situated between the Watson-Crick base pair of the two first strands. The precise position of TINA within the triplex structure reveals key TINA-DNA interactions, which explains the high stabilization observed and will aid in the design of new and more efficient binders to DNA.
Collapse
Affiliation(s)
- Miguel Garavís
- Instituto de Química Física ‘Blas Cabrera’, (IQF-CSIC), Madrid 28006, Spain
| | - Patrick J B Edwards
- School of Natural Sciences, Massey University, Palmerston North 4412, New Zealand
| | | | - Osman Doluca
- School of Natural Sciences, Massey University, Palmerston North 4412, New Zealand
| | | | - Carlos González
- Instituto de Química Física ‘Blas Cabrera’, (IQF-CSIC), Madrid 28006, Spain
| |
Collapse
|
3
|
Maldonado R, Längst G. The chromatin - triple helix connection. Biol Chem 2023; 404:1037-1049. [PMID: 37506218 DOI: 10.1515/hsz-2023-0189] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023]
Abstract
Mammalian genomes are extensively transcribed, producing a large number of coding and non-coding transcripts. A large fraction of the nuclear RNAs is physically associated with chromatin, functioning in gene activation and silencing, shaping higher-order genome organisation, such as involvement in long-range enhancer-promoter interactions, transcription hubs, heterochromatin, nuclear bodies and phase transitions. Different mechanisms allow the tethering of these chromatin-associated RNAs (caRNA) to chromosomes, including RNA binding proteins, the RNA polymerases and R-loops. In this review, we focus on the sequence-specific targeting of RNA to DNA by forming triple helical structures and describe its interplay with chromatin. It turns out that nucleosome positioning at triple helix target sites and the nucleosome itself are essential factors in determining the formation and stability of triple helices. The histone H3-tail plays a critical role in triple helix stabilisation, and the role of its epigenetic modifications in this process is discussed.
Collapse
Affiliation(s)
- Rodrigo Maldonado
- Institute of Anatomy, Histology, and Pathology, Faculty of Medicine, Universidad Austral de Chile, 5090000 Valdivia, Chile
| | - Gernot Längst
- Regensburg Center for Biochemistry (RCB), University of Regensburg, D-93053 Regensburg, Germany
| |
Collapse
|
4
|
Kohestani H, Wereszczynski J. The effects of RNA.DNA-DNA triple helices on nucleosome structures and dynamics. Biophys J 2023; 122:1229-1239. [PMID: 36798026 PMCID: PMC10111275 DOI: 10.1016/j.bpj.2023.02.013] [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: 07/02/2022] [Revised: 01/22/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023] Open
Abstract
Noncoding RNAs (ncRNAs) are an emerging epigenetic factor and have been recognized as playing a key role in many gene expression pathways. Structurally, binding of ncRNAs to isolated DNA is strongly dependent on sequence complementary and results in the formation of an RNA.DNA-DNA (RDD) triple helix. However, in vivo DNA is not isolated but is rather packed in chromatin fibers, the fundamental unit of which is the nucleosome. Biochemical experiments have shown that ncRNA binding to nucleosomal DNA is elevated at DNA entry and exit sites and is dependent on the presence of the H3 N-terminal tails. However, the structural and dynamical bases for these mechanisms remain unknown. Here, we have examined the mechanisms and effects of RDD formation in the context of the nucleosome using a series of all-atom molecular dynamics simulations. Results highlight the importance of DNA sequence on complex stability, elucidate the effects of the H3 tails on RDD structures, show how RDD formation impacts the structure and dynamics of the H3 tails, and show how RNA alters the local and global DNA double-helical structure. Together, our results suggest ncRNAs can modify nucleosome, and potentially higher-order chromatin, structures and dynamics as a means of exerting epigenetic control.
Collapse
Affiliation(s)
- Havva Kohestani
- Department of Biology, Illinois Institute of Technology, Chicago, Illinois
| | - Jeff Wereszczynski
- Departments of Physics & Biology, Illinois Institute of Technology, Chicago, Illinois.
| |
Collapse
|
5
|
McGorman B, Fantoni NZ, O'Carroll S, Ziemele A, El-Sagheer AH, Brown T, Kellett A. Enzymatic Synthesis of Chemical Nuclease Triplex-Forming Oligonucleotides with Gene-Silencing Applications. Nucleic Acids Res 2022; 50:5467-5481. [PMID: 35640595 PMCID: PMC9177962 DOI: 10.1093/nar/gkac438] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/10/2022] [Accepted: 05/09/2022] [Indexed: 11/12/2022] Open
Abstract
Triplex-forming oligonucleotides (TFOs) are short, single-stranded oligomers that hybridise to a specific sequence of duplex DNA. TFOs can block transcription and thereby inhibit protein production, making them highly appealing in the field of antigene therapeutics. In this work, a primer extension protocol was developed to enzymatically prepare chemical nuclease TFO hybrid constructs, with gene-silencing applications. Click chemistry was employed to generate novel artificial metallo-nuclease (AMN)-dNTPs, which were selectively incorporated into the TFO strand by a DNA polymerase. This purely enzymatic protocol was then extended to facilitate the construction of 5-methylcytosine (5mC) modified TFOs that displayed increased thermal stability. The utility of the enzymatically synthesised di-(2-picolyl)amine (DPA)-TFOs was assessed and compared to a specifically prepared solid-phase synthesis counterpart through gel electrophoresis, quantitative PCR, and Sanger sequencing, which revealed similar recognition and damage properties to target genes. The specificity was then enhanced through coordinated designer intercalators-DPQ and DPPZ-and high-precision DNA cleavage was achieved. To our knowledge, this is the first example of the enzymatic production of an AMN-TFO hybrid and is the largest base modification incorporated using this method. These results indicate how chemical nuclease-TFOs may overcome limitations associated with non-molecularly targeted metallodrugs and open new avenues for artificial gene-editing technology.
Collapse
Affiliation(s)
- Bríonna McGorman
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Nicolò Zuin Fantoni
- Chemistry Research Laboratory, University of Oxford, South Parks Rd, Oxford, UK
| | - Sinéad O'Carroll
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Anna Ziemele
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Afaf H El-Sagheer
- Chemistry Research Laboratory, University of Oxford, South Parks Rd, Oxford, UK.,Department of Science and Mathematics, Suez University, Faculty of Petroleum and Mining, Engineering, Suez 43721, Egypt
| | - Tom Brown
- Chemistry Research Laboratory, University of Oxford, South Parks Rd, Oxford, UK
| | - Andrew Kellett
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.,SSPC, the Science Foundation Ireland Research Centre for Pharmaceuticals, School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland
| |
Collapse
|
6
|
Khan S, Singh A, Nain N, Gulati S, Kukreti S. Sequence-specific recognition of a coding segment of human DACH1 gene via short pyrimidine/purine oligonucleotides. RSC Adv 2021; 11:40011-40021. [PMID: 35494143 PMCID: PMC9044637 DOI: 10.1039/d1ra06604h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 12/03/2021] [Indexed: 12/18/2022] Open
Abstract
With growing in vivo evidence of the roles of triplexes in biological processes, oligonucleotide-directed targeting of double-helical DNA for selective modulation of gene functions has become imperative in their therapeutic aspects. This study comprises a comparative investigation of 17-mer Py- and Pu-TFO for the formation of an intermolecular triplex with a 27-bp genomic homopurine–homopyrimidine track present in the transcriptional element of the human DACH1 gene. The biochemical and biophysical studies have revealed that triplex formation takes place only with Py-TFO and not with its Pu-counterpart. Non-denaturating gel electrophoresis indicated the formation of an intermolecular triplex in Py-motif with an increasing amount of Py-TFO, whereas no such interaction was observed for the Pu-counterpart. UV-thermal melting (Tm), circular dichroism (CD) and thermal difference spectra (TDS) studies confirmed the pyrimidine motif triplex formation, which was observed to be significantly pH-dependent and stable at acidic pH (5.2) in the presence of 100 mM Na+ ions. Contrarily, Pu-TFO was not found to bind to the target predominantly, owing to its self-association properties. Further studies have revealed that the GA-rich Pu-TFO adopts a homoduplex structure leading to a limit in its availability for triplex formation. These results may add to our understanding of sequence-specific gene targeting and give insight into designing more specific TFOs depending on genomic targets. Schematic representation of the proposed model of intermolecular triplex and homoduplex of used DNA sequences.![]()
Collapse
Affiliation(s)
- Shoaib Khan
- Nucleic Acid Research Laboratory, Department of Chemistry, University of Delhi Delhi-110007 India
| | - Anju Singh
- Department of Chemistry, Ramjas College, University of Delhi Delhi-110007 India
| | - Nishu Nain
- Nucleic Acid Research Laboratory, Department of Chemistry, University of Delhi Delhi-110007 India
| | - Srishty Gulati
- Nucleic Acid Research Laboratory, Department of Chemistry, University of Delhi Delhi-110007 India
| | - Shrikant Kukreti
- Nucleic Acid Research Laboratory, Department of Chemistry, University of Delhi Delhi-110007 India
| |
Collapse
|
7
|
Su Y, Bayarjargal M, Hale TK, Filichev VV. DNA with zwitterionic and negatively charged phosphate modifications: Formation of DNA triplexes, duplexes and cell uptake studies. Beilstein J Org Chem 2021; 17:749-761. [PMID: 33828619 PMCID: PMC8022206 DOI: 10.3762/bjoc.17.65] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/11/2021] [Indexed: 12/15/2022] Open
Abstract
Two phosphate modifications were introduced into the DNA backbone using the Staudinger reaction between the 3’,5’-dinucleoside β-cyanoethyl phosphite triester formed during DNA synthesis and sulfonyl azides, 4-(azidosulfonyl)-N,N,N-trimethylbutan-1-aminium iodide (N+ azide) or p-toluenesulfonyl (tosyl or Ts) azide, to provide either a zwitterionic phosphoramidate with N+ modification or a negatively charged phosphoramidate for Ts modification in the DNA sequence. The incorporation of these N+ and Ts modifications led to the formation of thermally stable parallel DNA triplexes, regardless of the number of modifications incorporated into the oligodeoxynucleotides (ONs). For both N+ and Ts-modified ONs, the antiparallel duplexes formed with complementary RNA were more stable than those formed with complementary DNA (except for ONs with modification in the middle of the sequence). Additionally, the incorporation of N+ modifications led to the formation of duplexes with a thermal stability that was less dependent on the ionic strength than native DNA duplexes. The thermodynamic analysis of the melting curves revealed that it is the reduction in unfavourable entropy, despite the decrease in favourable enthalpy, which is responsible for the stabilisation of duplexes with N+ modification. N+ONs also demonstrated greater resistance to nuclease digestion by snake venom phosphodiesterase I than the corresponding Ts-ONs. Cell uptake studies showed that Ts-ONs can enter the nucleus of mouse fibroblast NIH3T3 cells without any transfection reagent, whereas, N+ONs remain concentrated in vesicles within the cytoplasm. These results indicate that both N+ and Ts-modified ONs are promising for various in vivo applications.
Collapse
Affiliation(s)
- Yongdong Su
- School of Fundamental Sciences, Massey University, Private Bag 11-222, 4442 Palmerston North, New Zealand
| | - Maitsetseg Bayarjargal
- School of Fundamental Sciences, Massey University, Private Bag 11-222, 4442 Palmerston North, New Zealand
| | - Tracy K Hale
- School of Fundamental Sciences, Massey University, Private Bag 11-222, 4442 Palmerston North, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, Auckland 1142, New Zealand
| | - Vyacheslav V Filichev
- School of Fundamental Sciences, Massey University, Private Bag 11-222, 4442 Palmerston North, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, Auckland 1142, New Zealand
| |
Collapse
|
8
|
Lauria T, Slator C, McKee V, Müller M, Stazzoni S, Crisp AL, Carell T, Kellett A. A Click Chemistry Approach to Developing Molecularly Targeted DNA Scissors. Chemistry 2020; 26:16782-16792. [PMID: 32706904 DOI: 10.1002/chem.202002860] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/23/2020] [Indexed: 12/21/2022]
Abstract
Nucleic acid click chemistry was used to prepare a family of chemically modified triplex forming oligonucleotides (TFOs) for application as a new gene-targeted technology. Azide-bearing phenanthrene ligands-designed to promote triplex stability and copper binding-were 'clicked' to alkyne-modified parallel TFOs. Using this approach, a library of TFO hybrids was prepared and shown to effectively target purine-rich genetic elements in vitro. Several of the hybrids provide significant stabilisation toward melting in parallel triplexes (>20 °C) and DNA damage can be triggered upon copper binding in the presence of added reductant. Therefore, the TFO and 'clicked' ligands work synergistically to provide sequence-selectivity to the copper cutting unit which, in turn, confers high stabilisation to the DNA triplex. To extend the boundaries of this hybrid system further, a click chemistry-based di-copper binding ligand was developed to accommodate designer ancillary ligands such as DPQ and DPPZ. When this ligand was inserted into a TFO, a dramatic improvement in targeted oxidative cleavage is afforded.
Collapse
Affiliation(s)
- Teresa Lauria
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, 9, Ireland
| | - Creina Slator
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, 9, Ireland
| | - Vickie McKee
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, 9, Ireland.,Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Markus Müller
- Department of Chemistry, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Samuele Stazzoni
- Department of Chemistry, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Antony L Crisp
- Department of Chemistry, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Thomas Carell
- Department of Chemistry, Ludwig-Maximilians-Universität, Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Andrew Kellett
- School of Chemical Sciences and National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, 9, Ireland.,CÚRAM, Centre for Research in Medical Devices, Dublin City University, Glasnevin, Dublin, 9, Ireland
| |
Collapse
|
9
|
O'Neill RJ. Seq'ing identity and function in a repeat-derived noncoding RNA world. Chromosome Res 2020; 28:111-127. [PMID: 32146545 PMCID: PMC7393779 DOI: 10.1007/s10577-020-09628-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 01/06/2023]
Abstract
Innovations in high-throughout sequencing approaches are being marshaled to both reveal the composition of the abundant and heterogeneous noncoding RNAs that populate cell nuclei and lend insight to the mechanisms by which noncoding RNAs influence chromosome biology and gene expression. This review focuses on some of the recent technological developments that have enabled the isolation of nascent transcripts and chromatin-associated and DNA-interacting RNAs. Coupled with emerging genome assembly and analytical approaches, the field is poised to achieve a comprehensive catalog of nuclear noncoding RNAs, including those derived from repetitive regions within eukaryotic genomes. Herein, particular attention is paid to the challenges and advances in the sequence analyses of repeat and transposable element-derived noncoding RNAs and in ascribing specific function(s) to such RNAs.
Collapse
Affiliation(s)
- Rachel J O'Neill
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, 06269, USA.
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, 06269, USA.
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, 06030, USA.
| |
Collapse
|
10
|
Functional Prediction of Candidate MicroRNAs for CRC Management Using in Silico Approach. Int J Mol Sci 2019; 20:ijms20205190. [PMID: 31635135 PMCID: PMC6834124 DOI: 10.3390/ijms20205190] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/13/2019] [Accepted: 09/14/2019] [Indexed: 02/07/2023] Open
Abstract
Approximately 30–50% of malignant growths can be prevented by avoiding risk factors and implementing evidence-based strategies. Colorectal cancer (CRC) accounted for the second most common cancer and the third most common cause of cancer death worldwide. This cancer subtype can be reduced by early detection and patients’ management. In this study, the functional roles of the identified microRNAs were determined using an in silico pipeline. Five microRNAs identified using an in silico approach alongside their seven target genes from our previous study were used as datasets in this study. Furthermore, the secondary structure and the thermodynamic energies of the microRNAs were revealed by Mfold algorithm. The triplex binding ability of the oligonucleotide with the target promoters were analyzed by Trident. Finally, evolutionary stage-specific somatic events and co-expression analysis of the target genes in CRC were analyzed by SEECancer and GeneMANIA plugin in Cytoscape. Four of the five microRNAs have the potential to form more than one secondary structure. The ranges of the observed/expected ratio of CpG dinucleotides of these genes range from 0.60 to 1.22. Three of the candidate microRNA were capable of forming multiple triplexes along with three of the target mRNAs. Four of the total targets were involved in either early or metastatic stage-specific events while three other genes were either a product of antecedent or subsequent events of the four genes implicated in CRC. The secondary structure of the candidate microRNAs can be used to explain the different degrees of genetic regulation in CRC due to their conformational role to modulate target interaction. Furthermore, due to the regulation of important genes in the CRC pathway and the enrichment of the microRNA with triplex binding sites, they may be a useful diagnostic biomarker for the disease subtype.
Collapse
|
11
|
Sentürk Cetin N, Kuo CC, Ribarska T, Li R, Costa IG, Grummt I. Isolation and genome-wide characterization of cellular DNA:RNA triplex structures. Nucleic Acids Res 2019; 47:2306-2321. [PMID: 30605520 PMCID: PMC6411930 DOI: 10.1093/nar/gky1305] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 12/18/2018] [Accepted: 12/27/2018] [Indexed: 12/21/2022] Open
Abstract
RNA can directly bind to purine-rich DNA via Hoogsteen base pairing, forming a DNA:RNA triple helical structure that anchors the RNA to specific sequences and allows guiding of transcription regulators to distinct genomic loci. To unravel the prevalence of DNA:RNA triplexes in living cells, we have established a fast and cost-effective method that allows genome-wide mapping of DNA:RNA triplex interactions. In contrast to previous approaches applied for the identification of chromatin-associated RNAs, this method uses protein-free nucleic acids isolated from chromatin. High-throughput sequencing and computational analysis of DNA-associated RNA revealed a large set of RNAs which originate from non-coding and coding loci, including super-enhancers and repeat elements. Combined analysis of DNA-associated RNA and RNA-associated DNA identified genomic DNA:RNA triplex structures. The results suggest that triplex formation is a general mechanism of RNA-mediated target-site recognition, which has major impact on biological functions.
Collapse
Affiliation(s)
- Nevcin Sentürk Cetin
- Division of Molecular Biology of the Cell II, German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Chao-Chung Kuo
- Institute for Computational Genomics, RWTH University Medical School Aachen, Germany
| | - Teodora Ribarska
- Division of Molecular Biology of the Cell II, German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Ronghui Li
- Institute for Computational Genomics, RWTH University Medical School Aachen, Germany
| | - Ivan G Costa
- Institute for Computational Genomics, RWTH University Medical School Aachen, Germany
| | - Ingrid Grummt
- Division of Molecular Biology of the Cell II, German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| |
Collapse
|
12
|
Matsuno Y, Yamashita T, Wagatsuma M, Yamakage H. Convergence in LINE-1 nucleotide variations can benefit redundantly forming triplexes with lncRNA in mammalian X-chromosome inactivation. Mob DNA 2019; 10:33. [PMID: 31384315 PMCID: PMC6664574 DOI: 10.1186/s13100-019-0173-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 07/08/2019] [Indexed: 01/01/2023] Open
Abstract
Background Associations between X-inactive transcript (Xist)–long noncoding RNA (lncRNA) and chromatin are critical intermolecular interactions in the X-chromosome inactivation (XCI) process. Despite high-resolution analyses of the Xist RNA-binding sites, specific interaction sequences are yet to be identified. Based on elusive features of the association between Xist RNA and chromatin and the possible existence of multiple low-affinity binding sites in Xist RNA, we defined short motifs (≥5 nucleotides), termed as redundant UC/TC (r-UC/TC) or AG (r-AG) motifs, which may help in the mediation of triplex formation between the lncRNAs and duplex DNA. Results The study showed that r-UC motifs are densely dispersed throughout mouse and human Xist/XIST RNAs, whereas r-AG motifs are even more densely dispersed along opossum RNA-on-the-silent X (Rsx) RNA, and also along both full-length and truncated long interspersed nuclear elements (LINE-1s, L1s) of the three species. Predicted secondary structures of the lncRNAs showed that the length range of these sequence motifs available for forming triplexes was even shorter, mainly 5- to 9-nucleotides long. Quartz crystal microbalance (QCM) measurements and Monte Carlo (MC) simulations indicated that minimum-length motifs can reinforce the binding state by increasing the copy number of the motifs in the same RNA or DNA molecule. Further, r-AG motifs in L1s had a similar length-distribution pattern, regardless of the similarities in the length or sequence of L1s across the three species; this also applies to high-frequency mutations in r-AG motifs, which suggests convergence in L1 sequence variations. Conclusions Multiple short motifs in both RNA and duplex DNA molecules could be brought together to form triplexes with either Hoogsteen or reverse Hoogsteen hydrogen bonding, by which their associations are cooperatively enhanced. This novel triplex interaction could be involved in associations between lncRNA and chromatin in XCI, particularly at the sites of L1s. Potential binding of Xist/XIST/Rsx RNAs specifically at L1s is most likely preserved through the r-AG motifs conserved in mammalian L1s through convergence in L1 nucleotide variations and by maintaining a particular r-UC/r-AG motif ratio in each of these lncRNAs, irrespective of their poorly conserved sequences. Electronic supplementary material The online version of this article (10.1186/s13100-019-0173-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Yoko Matsuno
- 1Division of Clinical Preventive Medicine, Niigata University, Niigata, Japan
| | - Takefumi Yamashita
- 2Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | | | | |
Collapse
|
13
|
Maldonado R, Schwartz U, Silberhorn E, Längst G. Nucleosomes Stabilize ssRNA-dsDNA Triple Helices in Human Cells. Mol Cell 2019; 73:1243-1254.e6. [PMID: 30770238 DOI: 10.1016/j.molcel.2019.01.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/07/2018] [Accepted: 01/03/2019] [Indexed: 02/06/2023]
Abstract
Chromatin-associated non-coding RNAs modulate the epigenetic landscape and its associated gene expression program. The formation of triple helices is one mechanism of sequence-specific targeting of RNA to chromatin. With this study, we show an important role of the nucleosome and its relative positioning to the triplex targeting site (TTS) in stabilizing RNA-DNA triplexes in vitro and in vivo. Triplex stabilization depends on the histone H3 tail and the location of the TTS close to the nucleosomal DNA entry-exit site. Genome-wide analysis of TTS-nucleosome arrangements revealed a defined chromatin organization with an enrichment of arrangements that allow triplex formation at active regulatory sites and accessible chromatin. We further developed a method to monitor nucleosome-RNA triplexes in vivo (TRIP-seq), revealing RNA binding to TTS sites adjacent to nucleosomes. Our data strongly support an activating role for RNA triplex-nucleosome complexes, pinpointing triplex-mediated epigenetic regulation in vivo.
Collapse
Affiliation(s)
- Rodrigo Maldonado
- Biochemistry Centre Regensburg (BCR), Universität Regensburg, 93053 Regensburg, Germany
| | - Uwe Schwartz
- Biochemistry Centre Regensburg (BCR), Universität Regensburg, 93053 Regensburg, Germany
| | - Elisabeth Silberhorn
- Biochemistry Centre Regensburg (BCR), Universität Regensburg, 93053 Regensburg, Germany
| | - Gernot Längst
- Biochemistry Centre Regensburg (BCR), Universität Regensburg, 93053 Regensburg, Germany.
| |
Collapse
|
14
|
Geel TM, Ruiters MHJ, Cool RH, Halby L, Voshart DC, Andrade Ruiz L, Niezen-Koning KE, Arimondo PB, Rots MG. The past and presence of gene targeting: from chemicals and DNA via proteins to RNA. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170077. [PMID: 29685979 PMCID: PMC5915719 DOI: 10.1098/rstb.2017.0077] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2017] [Indexed: 12/19/2022] Open
Abstract
The ability to target DNA specifically at any given position within the genome allows many intriguing possibilities and has inspired scientists for decades. Early gene-targeting efforts exploited chemicals or DNA oligonucleotides to interfere with the DNA at a given location in order to inactivate a gene or to correct mutations. We here describe an example towards correcting a genetic mutation underlying Pompe's disease using a nucleotide-fused nuclease (TFO-MunI). In addition to the promise of gene correction, scientists soon realized that genes could be inactivated or even re-activated without inducing potentially harmful DNA damage by targeting transcriptional modulators to a particular gene. However, it proved difficult to fuse protein effector domains to the first generation of programmable DNA-binding agents. The engineering of gene-targeting proteins (zinc finger proteins (ZFPs), transcription activator-like effectors (TALEs)) circumvented this problem. The disadvantage of protein-based gene targeting is that a fusion protein needs to be engineered for every locus. The recent introduction of CRISPR/Cas offers a flexible approach to target a (fusion) protein to the locus of interest using cheap designer RNA molecules. Many research groups now exploit this platform and the first human clinical trials have been initiated: CRISPR/Cas has kicked off a new era of gene targeting and is revolutionizing biomedical sciences.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.
Collapse
Affiliation(s)
- T M Geel
- Epigenetic Editing, Dept Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - M H J Ruiters
- Epigenetic Editing, Dept Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - R H Cool
- Chemical and Pharmaceutical Biology, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - L Halby
- CNRS FRE3600 ETaC, bât IBCG, 31062 Toulouse, France
| | - D C Voshart
- Epigenetic Editing, Dept Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - L Andrade Ruiz
- Epigenetic Editing, Dept Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - K E Niezen-Koning
- Laboratory of Metabolic Diseases, Dept Laboratory Medicine, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - P B Arimondo
- CNRS FRE3600 ETaC, bât IBCG, 31062 Toulouse, France
| | - M G Rots
- Epigenetic Editing, Dept Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| |
Collapse
|
15
|
Carr CE, Ganugula R, Shikiya R, Soto AM, Marky LA. Effect of dC → d(m 5C) substitutions on the folding of intramolecular triplexes with mixed TAT and C +GC base triplets. Biochimie 2018; 146:156-165. [PMID: 29277568 PMCID: PMC5811340 DOI: 10.1016/j.biochi.2017.12.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/19/2017] [Indexed: 12/31/2022]
Abstract
Oligonucleotide-directed triple helix formation has been recognized as a potential tool for targeting genes with high specificity. Cystosine methylation in the 5' position is both ubiquitous and a stable regulatory modification, which could potentially stabilize triple helix formation. In this work, we have used a combination of calorimetric and spectroscopic techniques to study the intramolecular unfolding of four triplexes and two duplexes. We used the following triplex control sequence, named Control Tri, d(AGAGAC5TCTCTC5TCTCT), where C5 are loops of five cytosines. From this sequence, we studied three other sequences with dC → d(m5C) substitutions on the Hoogsteen strand (2MeH), Crick strand (2MeC) and both strands (4MeHC). Calorimetric studies determined that methylation does increase the thermal and enthalpic stability, leading to an overall favorable free energy, and that this increased stability is cumulative, i.e. methylation on both the Hoogsteen and Crick strands yields the largest favorable free energy. The differential uptake of protons, counterions and water was determined. It was found that methylation increases cytosine protonation by shifting the apparent pKa value to a higher pH; this increase in proton uptake coincides with a release of counterions during folding of the triplex, likely due to repulsion from the increased positive charge from the protonated cytosines. The immobilization of water was not affected for triplexes with methylated cytosines on their Hoogsteen or Crick strands, but was seen for the triplex where both strands are methylated. This may be due to the alignment in the major groove of the methyl groups on the cytosines with the methyl groups on the thymines which causes an increase in structural water along the spine of the triplex.
Collapse
Affiliation(s)
- Carolyn E Carr
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, 68198-6025, USA
| | - Rajkumar Ganugula
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, 68198-6025, USA
| | - Ronald Shikiya
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, 68198-6025, USA
| | - Ana Maria Soto
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, 68198-6025, USA
| | - Luis A Marky
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE, 68198-6025, USA.
| |
Collapse
|
16
|
Lee HT, Carr CE, Khutsishvili I, Marky LA. Effect of Loop Length and Sequence on the Stability of DNA Pyrimidine Triplexes with TAT Base Triplets. J Phys Chem B 2017; 121:9175-9184. [PMID: 28875701 DOI: 10.1021/acs.jpcb.7b07591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report the thermodynamic contributions of loop length and loop sequence to the overall stability of DNA intramolecular pyrimidine triplexes. Two sets of triplexes were designed: in the first set, the C5 loop closing the triplex stem was replaced with 5'-CTnC loops (n = 1-5), whereas in the second set, both the duplex and triplex loops were replaced with a 5'-GCAA or 5'-AACG tetraloop. For the triplexes with a 5'-CTnC loop, the triplex with five bases in the loop has the highest stability relative to the control. A loop length lower than five compromises the strength of the base-pair stacks without decreasing the thermal stability, leading to a decreased enthalpy, whereas an increase in the loop length leads to a decreased enthalpy and a higher entropic penalty. The incorporation of the GCAA loop yielded more stable triplexes, whereas the incorporation of AACG in the triplex loop yielded a less stable triplex due to an unfavorable enthalpy term. Thus, addition of the GCAA tetraloop can cause an increase in the thermodynamics of the triplex without affecting the sequence or melting behavior and may result in an additional layer of genetic regulation.
Collapse
Affiliation(s)
- Hui-Ting Lee
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Carolyn E Carr
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Irine Khutsishvili
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Luis A Marky
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| |
Collapse
|
17
|
Brázda V, Coufal J. Recognition of Local DNA Structures by p53 Protein. Int J Mol Sci 2017; 18:ijms18020375. [PMID: 28208646 PMCID: PMC5343910 DOI: 10.3390/ijms18020375] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/03/2017] [Indexed: 02/06/2023] Open
Abstract
p53 plays critical roles in regulating cell cycle, apoptosis, senescence and metabolism and is commonly mutated in human cancer. These roles are achieved by interaction with other proteins, but particularly by interaction with DNA. As a transcription factor, p53 is well known to bind consensus target sequences in linear B-DNA. Recent findings indicate that p53 binds with higher affinity to target sequences that form cruciform DNA structure. Moreover, p53 binds very tightly to non-B DNA structures and local DNA structures are increasingly recognized to influence the activity of wild-type and mutant p53. Apart from cruciform structures, p53 binds to quadruplex DNA, triplex DNA, DNA loops, bulged DNA and hemicatenane DNA. In this review, we describe local DNA structures and summarize information about interactions of p53 with these structural DNA motifs. These recent data provide important insights into the complexity of the p53 pathway and the functional consequences of wild-type and mutant p53 activation in normal and tumor cells.
Collapse
Affiliation(s)
- Václav Brázda
- Institute of Biophysics, Academy of Sciences of the Czech Republic v.v.i., Královopolská 135, 612 65 Brno, Czech Republic.
| | - Jan Coufal
- Institute of Biophysics, Academy of Sciences of the Czech Republic v.v.i., Královopolská 135, 612 65 Brno, Czech Republic.
| |
Collapse
|
18
|
Bergquist H, Rocha CSJ, Álvarez-Asencio R, Nguyen CH, Rutland MW, Smith CIE, Good L, Nielsen PE, Zain R. Disruption of Higher Order DNA Structures in Friedreich's Ataxia (GAA)n Repeats by PNA or LNA Targeting. PLoS One 2016; 11:e0165788. [PMID: 27846236 PMCID: PMC5112992 DOI: 10.1371/journal.pone.0165788] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/07/2016] [Indexed: 01/08/2023] Open
Abstract
Expansion of (GAA)n repeats in the first intron of the Frataxin gene is associated with reduced mRNA and protein levels and the development of Friedreich’s ataxia. (GAA)n expansions form non-canonical structures, including intramolecular triplex (H-DNA), and R-loops and are associated with epigenetic modifications. With the aim of interfering with higher order H-DNA (like) DNA structures within pathological (GAA)n expansions, we examined sequence-specific interaction of peptide nucleic acid (PNA) with (GAA)n repeats of different lengths (short: n=9, medium: n=75 or long: n=115) by chemical probing of triple helical and single stranded regions. We found that a triplex structure (H-DNA) forms at GAA repeats of different lengths; however, single stranded regions were not detected within the medium size pathological repeat, suggesting the presence of a more complex structure. Furthermore, (GAA)4-PNA binding of the repeat abolished all detectable triplex DNA structures, whereas (CTT)5-PNA did not. We present evidence that (GAA)4-PNA can invade the DNA at the repeat region by binding the DNA CTT strand, thereby preventing non-canonical-DNA formation, and that triplex invasion complexes by (CTT)5-PNA form at the GAA repeats. Locked nucleic acid (LNA) oligonucleotides also inhibited triplex formation at GAA repeat expansions, and atomic force microscopy analysis showed significant relaxation of plasmid morphology in the presence of GAA-LNA. Thus, by inhibiting disease related higher order DNA structures in the Frataxin gene, such PNA and LNA oligomers may have potential for discovery of drugs aiming at recovering Frataxin expression.
Collapse
Affiliation(s)
- Helen Bergquist
- Department of Medical Biochemistry and Microbiology, Microbiology-Immunology, Uppsala University, Uppsala, Sweden
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, SE-141 86, Huddinge, Sweden
| | - Cristina S. J. Rocha
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, SE-141 86, Huddinge, Sweden
| | - Rubén Álvarez-Asencio
- KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Stockholm, Sweden
| | - Chi-Hung Nguyen
- Laboratoire de Pharmacochimie, Institut Curie, PSL Research University, UMR 9187 – U 1196 CNRS-Institut Curie, INSERM, Centre Universitaire, Orsay, France
| | - Mark. W. Rutland
- KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Stockholm, Sweden
| | - C. I. Edvard Smith
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, SE-141 86, Huddinge, Sweden
| | - Liam Good
- Department of Pathology and Infectious Diseases, Royal Veterinary College, University of London, United Kingdom
| | - Peter E. Nielsen
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, The Panum Institute, Copenhagen, Denmark
| | - Rula Zain
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, SE-141 86, Huddinge, Sweden
- Department of Clinical Genetics, Centre for Rare Diseases, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
- * E-mail:
| |
Collapse
|
19
|
Mukherjee A, Vasquez KM. Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks. J Vis Exp 2016. [PMID: 27911399 DOI: 10.3791/54678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
High mobility group box 1 (HMGB1) protein is a non-histone architectural protein that is involved in regulating many important functions in the genome, such as transcription, DNA replication, and DNA repair. HMGB1 binds to structurally distorted DNA with higher affinity than to canonical B-DNA. For example, we found that HMGB1 binds to DNA interstrand crosslinks (ICLs), which covalently link the two strands of the DNA, cause distortion of the helix, and if left unrepaired can cause cell death. Due to their cytotoxic potential, several ICL-inducing agents are currently used as chemotherapeutic agents in the clinic. While ICL-forming agents show preferences for certain base sequences (e.g., 5'-TA-3' is the preferred crosslinking site for psoralen), they largely induce DNA damage in an indiscriminate fashion. However, by covalently coupling the ICL-inducing agent to a triplex-forming oligonucleotide (TFO), which binds to DNA in a sequence-specific manner, targeted DNA damage can be achieved. Here, we use a TFO covalently conjugated on the 5' end to a 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) psoralen to generate a site-specific ICL on a mutation-reporter plasmid to use as a tool to study the architectural modification, processing, and repair of complex DNA lesions by HMGB1 in human cells. We describe experimental techniques to prepare TFO-directed ICLs on reporter plasmids, and to interrogate the association of HMGB1 with the TFO-directed ICLs in a cellular context using chromatin immunoprecipitation assays. In addition, we describe DNA supercoiling assays to assess specific architectural modification of the damaged DNA by measuring the amount of superhelical turns introduced on the psoralen-crosslinked plasmid by HMGB1. These techniques can be used to study the roles of other proteins involved in the processing and repair of TFO-directed ICLs or other targeted DNA damage in any cell line of interest.
Collapse
Affiliation(s)
- Anirban Mukherjee
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin
| | - Karen M Vasquez
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin;
| |
Collapse
|
20
|
Chen Z, Zhang H, Ma X, Lin Z, Zhang L, Chen G. A novel fluorescent reagent for recognition of triplex DNA with high specificity and selectivity. Analyst 2016; 140:7742-7. [PMID: 26456316 DOI: 10.1039/c5an01852h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A fluorescent agent (DMT) was screened for recognizing triplex DNA with a specific and selective characteristic, which was embedded into the triplex DNA structure. The triplex DNA was firstly formed by a complementary target sequence through two distinct and sequential events. The conditions including pH and hybridization time, fluorescent agent concentration and embedding time were optimized in the experiment. Under the optimum conditions, the fluorescence signal was enhanced up to 9-fold in comparison with the DMT embedding into the ssDNA, dsDNA and G-quadruplexes. Under the same fluorescence conditions, the changes of the fluorescence signal were also investigated by several kinds of base mismatched DNAs in the experiment. The results showed that our biosensor provided excellent discrimination efficiency toward the perfectly mismatched target DNA with no formation of triplex DNA. We preliminarily deduced the mechanism of the fluorescent reagent for recognizing triplex DNA with high specificity and selectivity.
Collapse
Affiliation(s)
- Zongbao Chen
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou, Fujian 350002, China. and Key Laboratory of Applied Organic Chemistry, College of Jiangxi Province Department of Chemistry, Shangrao Normal University, 334001, Jiangxi, China
| | - Huimi Zhang
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou, Fujian 350002, China.
| | - Xiaoming Ma
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou, Fujian 350002, China.
| | - Zhenyu Lin
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou, Fujian 350002, China.
| | - Lan Zhang
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou, Fujian 350002, China.
| | - Guonan Chen
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou, Fujian 350002, China.
| |
Collapse
|
21
|
Toscano-Garibay JD, Aquino-Jarquin G. Transcriptional regulation mechanism mediated by miRNA-DNA•DNA triplex structure stabilized by Argonaute. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1079-83. [PMID: 25086339 DOI: 10.1016/j.bbagrm.2014.07.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 12/19/2022]
Abstract
Transcription regulation depends on interactions between repressor or activator proteins with promoter sequences, while post-transcriptional regulation typically relies on microRNA (miRNA) interaction with sequences in 5' and 3'-Untranslated regions (UTRs) of messenger RNA (mRNA). However, several pieces of evidence suggest that miRNA:Argonaute (AGO) complexes may also suppress transcription through RNA interference (RNAi) components and epigenetic mechanisms. However, recent observations suggest that miRNA-induced transcriptional silencing could be exerted by an unknown mechanism independent of chromatin modifiers. The RNA-DNA•DNA triplex structure has emerged as an important RNA tertiary motif in which successive non-canonical base pairs form between a DNA-DNA duplex and a third strand. Frequently, promoters have Purine (PU)-rich tracts, and some Triplex-forming oligonucleotides (TFOs) targeting these regulatory regions have been shown to inhibit transcription selectively. Here, we summarize observations suggesting that miRNAs exert regulation over promoter regions through miRNA-DNA•DNA triplex structure formation stabilized by AGO proteins which represents a plausible model of RNA-mediated Transcriptional gene silencing (TGS).
Collapse
Affiliation(s)
- Julia D Toscano-Garibay
- Laboratorio de Medicina Regenerativa, Dirección de Investigación, Hospital Juárez de México, Av. Instituto Politécnico Nacional 5160, Col. Magdalena de las Salinas Del., Gustavo A. Madero, Distrito Federal C.P. 07760, Mexico
| | - Guillermo Aquino-Jarquin
- Laboratorio de Genómica, Genética y Bioinformática, Hospital Infantil de México Federico Gómez, Dr. Márquez No. 162, Col. Doctores, Delegación: Cuauhtémoc, México D.F. C.P. 06720, Mexico.
| |
Collapse
|
22
|
Miyoshi D, Ueda YM, Shimada N, Nakano SI, Sugimoto N, Maruyama A. Drastic stabilization of parallel DNA hybridizations by a polylysine comb-type copolymer with hydrophilic graft chain. ChemMedChem 2014; 9:2156-63. [PMID: 25045164 DOI: 10.1002/cmdc.201402157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Indexed: 11/08/2022]
Abstract
Electrostatic interactions play a major role in protein-DNA interactions. As a model system of a cationic protein, herein we focused on a comb-type copolymer of a polycation backbone and dextran side chains, poly(L-lysine)-graft-dextran (PLL-g-Dex), which has been reported to form soluble interpolyelectrolyte complexes with DNA strands. We investigated the effects of PLL-g-Dex on the conformation and thermodynamics of DNA oligonucleotides forming various secondary structures. Thermodynamic analysis of the DNA structures showed that the parallel conformations involved in both DNA duplexes and triplexes were significantly and specifically stabilized by PLL-g-Dex. On the basis of thermodynamic parameters, it was further possible to design DNA switches that undergo structural transition responding to PLL-g-Dex from an antiparallel duplex to a parallel triplex even with mismatches in the third strand hybridization. These results suggest that polycationic molecules are able to induce structural polymorphism of DNA oligonucleotides, because of the conformation-selective stabilization effects.
Collapse
Affiliation(s)
- Daisuke Miyoshi
- Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University 7-1-20 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047 (Japan).
| | | | | | | | | | | |
Collapse
|
23
|
Boulware SB, Christensen LA, Thames H, Coghlan L, Vasquez KM, Finch RA. Triplex-forming oligonucleotides targeting c-MYC potentiate the anti-tumor activity of gemcitabine in a mouse model of human cancer. Mol Carcinog 2013; 53:744-52. [PMID: 23681918 DOI: 10.1002/mc.22026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 02/25/2013] [Indexed: 12/21/2022]
Abstract
Antimetabolite chemotherapy remains an essential cancer treatment modality, but often produces only marginal benefit due to the lack of tumor specificity, the development of drug resistance, and the refractoriness of slowly proliferating cells in solid tumors. Here, we report a novel strategy to circumvent the proliferation-dependence of traditional antimetabolite-based therapies. Triplex-forming oligonucleotides (TFOs) were used to target site-specific DNA damage to the human c-MYC oncogene, thereby inducing replication-independent, unscheduled DNA repair synthesis (UDS) preferentially in the TFO-targeted region. The TFO-directed UDS facilitated incorporation of the antimetabolite, gemcitabine (GEM), into the damaged oncogene, thereby potentiating the anti-tumor activity of GEM. Mice bearing COLO 320DM human colon cancer xenografts (containing amplified c-MYC) were treated with a TFO targeted to c-MYC in combination with GEM. Tumor growth inhibition produced by the combination was significantly greater than with either TFO or GEM alone. Specific TFO binding to the genomic c-MYC gene was demonstrated, and TFO-induced DNA damage was confirmed by NBS1 accumulation, supporting a mechanism of enhanced efficacy of GEM via TFO-targeted DNA damage-induced UDS. Thus, coupling antimetabolite chemotherapeutics with a strategy that facilitates selective targeting of cells containing amplification of cancer-relevant genes can improve their activity against solid tumors, while possibly minimizing host toxicity.
Collapse
Affiliation(s)
- Stephen B Boulware
- Division of Pharmacology and Toxicology, The University of Texas at Austin, Austin, Texas
| | | | | | | | | | | |
Collapse
|
24
|
Taniguchi Y, Sasaki S. An efficient antigene activity and antiproliferative effect by targeting the Bcl-2 or survivin gene with triplex forming oligonucleotides containing a W-shaped nucleoside analogue (WNA-βT). Org Biomol Chem 2013; 10:8336-41. [PMID: 22987068 DOI: 10.1039/c2ob26431e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Triplex forming oligonucleotides (TFOs) are some of the most promising tools in the antigene strategy for the development of gene targeting therapeutics. However, the stable triplex formation is restricted to the homopurine sequences consisting of purine nucleosides, dG and dA. Therefore, the T or dC nucleoside in the homopurine strand inhibits the stable triplex formation. We have developed W-shaped nucleoside analogues (WNAs) for the formation of the unnatural type triplex DNA, with sequences containing the interrupting site in an antiparallel triplex formation. In the present study, we tested the antigene effect of TFOs having WNA-βT, which increased the stability of the triplex formation with a target sequence including the TA interrupting site. We designed the GU TFO (WNA) and GU TFO (natural) for targeting sequences of the Bcl-2 or survivin oncogene. The gel shift assay showed that the TFO (WNA) formed more stable triplexes than the natural TFO. Remarkably, the Bcl-2- or survivin-targeted TFO (WNA) inhibited the cell proliferation and induced a caspase-dependent apoptosis. It was confirmed that the survivin-targeted TFO (WNA) more effectively decreased the number of survivin products in the A549 cell than the natural TFOs.
Collapse
Affiliation(s)
- Yosuke Taniguchi
- Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, Japan.
| | | |
Collapse
|
25
|
Doluca O, Withers JM, Filichev VV. Molecular engineering of guanine-rich sequences: Z-DNA, DNA triplexes, and G-quadruplexes. Chem Rev 2013; 113:3044-83. [PMID: 23391174 DOI: 10.1021/cr300225q] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Osman Doluca
- Institute of Fundamental Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand
| | | | | |
Collapse
|
26
|
Papadakis G, Gizeli E. In silico search of DNA drugs targeting oncogenes. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2012; 9:1826-1830. [PMID: 23221090 DOI: 10.1109/tcbb.2012.127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Triplex forming oligonucleotides (TFOs) represent a class of drug candidates for antigene therapy. Based on strict criteria, we investigated the potential of 25 known oncogenes to be regulated by TFOs in the mRNA synthesis level and we report specific target sequences found in seven of these genes.
Collapse
Affiliation(s)
- George Papadakis
- Department of Biology, University of Crete and Institute of Molecular Biology and Biotechnology (IMBB), Foundation for Research and Technology Hellas (FORTH), 100 Nikolaou Plastira str, Heraklion 70013, Greece.
| | | |
Collapse
|
27
|
Buske FA, Bauer DC, Mattick JS, Bailey TL. Triplexator: detecting nucleic acid triple helices in genomic and transcriptomic data. Genome Res 2012; 22:1372-81. [PMID: 22550012 PMCID: PMC3396377 DOI: 10.1101/gr.130237.111] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 03/20/2012] [Indexed: 11/28/2022]
Abstract
Double-stranded DNA is able to form triple-helical structures by accommodating a third nucleotide strand in its major groove. This sequence-specific process offers a potent mechanism for targeting genomic loci of interest that is of great value for biotechnological and gene-therapeutic applications. It is likely that nature has leveraged this addressing system for gene regulation, because computational studies have uncovered an abundance of putative triplex target sites in various genomes, with enrichment particularly in gene promoters. However, to draw a more complete picture of the in vivo role of triplexes, not only the putative targets but also the sequences acting as the third strand and their capability to pair with the predicted target sites need to be studied. Here we present Triplexator, the first computational framework that integrates all aspects of triplex formation, and showcase its potential by discussing research examples for which the different aspects of triplex formation are important. We find that chromatin-associated RNAs have a significantly higher fraction of sequence features able to form triplexes than expected at random, suggesting their involvement in gene regulation. We furthermore identify hundreds of human genes that contain sequence features in their promoter predicted to be able to form a triplex with a target within the same promoter, suggesting the involvement of triplexes in feedback-based gene regulation. With focus on biotechnological applications, we screen mammalian genomes for high-affinity triplex target sites that can be used to target genomic loci specifically and find that triplex formation offers a resolution of ~1300 nt.
Collapse
Affiliation(s)
- Fabian A. Buske
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, 4072 QLD, Australia
| | - Denis C. Bauer
- Division of Mathematics, Informatics, and Statistics, CSIRO, Sydney, 2113 NSW, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, 4072 QLD, Australia
| | - John S. Mattick
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, 4072 QLD, Australia
- Garvan Institute of Medical Research, Sydney, 2010 NSW, Australia
| | - Timothy L. Bailey
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, 4072 QLD, Australia
| |
Collapse
|
28
|
Carrascosa LG, Gómez-Montes S, Aviñó A, Nadal A, Pla M, Eritja R, Lechuga LM. Sensitive and label-free biosensing of RNA with predicted secondary structures by a triplex affinity capture method. Nucleic Acids Res 2012; 40:e56. [PMID: 22241768 PMCID: PMC3333861 DOI: 10.1093/nar/gkr1304] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A novel biosensing approach for the label-free detection of nucleic acid sequences of short and large lengths has been implemented, with special emphasis on targeting RNA sequences with secondary structures. The approach is based on selecting 8-aminoadenine-modified parallel-stranded DNA tail-clamps as affinity bioreceptors. These receptors have the ability of creating a stable triplex-stranded helix at neutral pH upon hybridization with the nucleic acid target. A surface plasmon resonance biosensor has been used for the detection. With this strategy, we have detected short DNA sequences (32-mer) and purified RNA (103-mer) at the femtomol level in a few minutes in an easy and level-free way. This approach is particularly suitable for the detection of RNA molecules with predicted secondary structures, reaching a limit of detection of 50 fmol without any label or amplification steps. Our methodology has shown a marked enhancement for the detection (18% for short DNA and 54% for RNA), when compared with the conventional duplex approach, highlighting the large difficulty of the duplex approach to detect nucleic acid sequences, especially those exhibiting stable secondary structures. We believe that our strategy could be of great interest to the RNA field.
Collapse
Affiliation(s)
- Laura G Carrascosa
- Nanobiosensors and Bioanalytical Applications Group, CIBER-BBN and Research Center on Nanoscience and Nanotechnology (CIN2) CSIC, Barcelona, Spain.
| | | | | | | | | | | | | |
Collapse
|
29
|
Doluca O, Boutorine AS, Filichev VV. Triplex-Forming Twisted Intercalating Nucleic Acids (TINAs): Design Rules, Stabilization of Antiparallel DNA Triplexes and Inhibition of G-Quartet-Dependent Self-Association. Chembiochem 2011; 12:2365-74. [DOI: 10.1002/cbic.201100354] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
30
|
Targeted gene modification of hematopoietic progenitor cells in mice following systemic administration of a PNA-peptide conjugate. Mol Ther 2011; 20:109-18. [PMID: 21829173 DOI: 10.1038/mt.2011.163] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hematopoietic stem cell (HSC) gene therapy offers promise for the development of new treatments for a variety of hematologic disorders. However, efficient in vivo modification of HSCs has proved challenging, thus imposing constraints on the therapeutic potential of this approach. Herein, we provide a gene-targeting strategy that allows site-specific in vivo gene modification in the HSCs of mice. Through conjugation of a triplex-forming peptide nucleic acid (PNA) to the transport peptide, antennapedia (Antp), we achieved successful in vivo chromosomal genomic modification of hematopoietic progenitor cells, while still retaining intact differentiation capabilities. Following systemic administration of PNA-Antp conjugates, sequence-specific gene modification was observed in multiple somatic tissues as well as within multiple compartments of the hematopoietic system, including erythroid, myeloid, and lymphoid cell lineages. As a true functional measure of gene targeting in a long-term renewable HSC, we also demonstrate preserved genomic modification in the bone marrow and spleen of primary recipient mice following transplantation of bone marrow from PNA-Antp-treated donor mice. Our approach offers a minimally invasive alternative to ex vivo gene therapy, by eliminating the need for the complex steps of stem cell mobilization and harvesting, ex vivo manipulation, and transplantation of stem cells. Therefore, our approach may provide new options for individualized therapies in the treatment of monogenic hematologic diseases such as sickle cell anemia and thalassemia.
Collapse
|
31
|
Abstract
Tumor necrosis factor-α (TNF-α), a proinflammatory cytokine, plays a key role in the pathogenesis of many inflammatory diseases, including arthritis. Neutralization of this cytokine by anti-TNF-α antibodies has shown its efficacy in rheumatoid arthritis (RA) and is now widely used. Nevertheless, some patients currently treated with anti-TNF-α remain refractory or become nonresponder to these treatments. In this context, there is a need for new or complementary therapeutic strategies. In this study, we investigated in vitro and in vivo anti-inflammatory potentialities of an anti-TNF-α triplex-forming oligonucleotide (TFO), as judged from effects on two rat arthritis models. The inhibitory activity of this TFO on articular cells (synoviocytes and chondrocytes) was verified and compared to that of small interfering RNA (siRNA) in vitro. The use of the anti-TNF-α TFO as a preventive and local treatment in both acute and chronic arthritis models significantly reduced disease development. Furthermore, the TFO efficiently blocked synovitis and cartilage and bone destruction in the joints. The results presented here provide the first evidence that gene targeting by anti-TNF-α TFO modulates arthritis in vivo, thus providing proof-of-concept that it could be used as therapeutic tool for TNF-α-dependent inflammatory disorders.
Collapse
|
32
|
Buske FA, Mattick JS, Bailey TL. Potential in vivo roles of nucleic acid triple-helices. RNA Biol 2011; 8:427-39. [PMID: 21525785 DOI: 10.4161/rna.8.3.14999] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The ability of double-stranded DNA to form a triple-helical structure by hydrogen bonding with a third strand is well established, but the biological functions of these structures remain largely unknown. There is considerable albeit circumstantial evidence for the existence of nucleic triplexes in vivo and their potential participation in a variety of biological processes including chromatin organization, DNA repair, transcriptional regulation, and RNA processing has been investigated in a number of studies to date. There is also a range of possible mechanisms to regulate triplex formation through differential expression of triplex-forming RNAs, alteration of chromatin accessibility, sequence unwinding and nucleotide modifications. With the advent of next generation sequencing technology combined with targeted approaches to isolate triplexes, it is now possible to survey triplex formation with respect to their genomic context, abundance and dynamical changes during differentiation and development, which may open up new vistas in understanding genome biology and gene regulation.
Collapse
Affiliation(s)
- Fabian A Buske
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD Australia
| | | | | |
Collapse
|
33
|
|
34
|
Mukherjee A, Vasquez KM. Triplex technology in studies of DNA damage, DNA repair, and mutagenesis. Biochimie 2011; 93:1197-208. [PMID: 21501652 DOI: 10.1016/j.biochi.2011.04.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 04/01/2011] [Indexed: 12/18/2022]
Abstract
Triplex-forming oligonucleotides (TFOs) can bind to the major groove of homopurine-homopyrimidine stretches of double-stranded DNA in a sequence-specific manner through Hoogsteen hydrogen bonding to form DNA triplexes. TFOs by themselves or conjugated to reactive molecules can be used to direct sequence-specific DNA damage, which in turn results in the induction of several DNA metabolic activities. Triplex technology is highly utilized as a tool to study gene regulation, molecular mechanisms of DNA repair, recombination, and mutagenesis. In addition, TFO targeting of specific genes has been exploited in the development of therapeutic strategies to modulate DNA structure and function. In this review, we discuss advances made in studies of DNA damage, DNA repair, recombination, and mutagenesis by using triplex technology to target specific DNA sequences.
Collapse
Affiliation(s)
- Anirban Mukherjee
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, 1400 Barbara Jordan Blvd., Austin, TX 78723, USA
| | | |
Collapse
|
35
|
Zheng R, Shen Z, Tripathi V, Xuan Z, Freier SM, Bennett CF, Prasanth SG, Prasanth KV. Polypurine-repeat-containing RNAs: a novel class of long non-coding RNA in mammalian cells. J Cell Sci 2010; 123:3734-44. [PMID: 20940252 DOI: 10.1242/jcs.070466] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In higher eukaryotic cells, long non-protein-coding RNAs (lncRNAs) have been implicated in a wide array of cellular functions. Cell- or tissue-specific expression of lncRNA genes encoded in the mammalian genome is thought to contribute to the complex gene networks needed to regulate cellular function. Here, we have identified a novel species of polypurine triplet repeat-rich lncRNAs, designated as GAA repeat-containing RNAs (GRC-RNAs), that localize to numerous punctate foci in the mammalian interphase nuclei. GRC-RNAs consist of a heterogeneous population of RNAs, ranging in size from ~1.5 kb to ~4 kb and localize to subnuclear domains, several of which associate with GAA.TTC-repeat-containing genomic regions. GRC-RNAs are components of the nuclear matrix and interact with various nuclear matrix-associated proteins. In mitotic cells, GRC-RNAs form distinct cytoplasmic foci and, in telophase and G1 cells, localize to the midbody, a structure involved in accurate cell division. Differentiation of tissue culture cells leads to a decrease in the number of GRC-RNA nuclear foci, albeit with an increase in size as compared with proliferating cells. Conversely, the number of GRC-RNA foci increases during cellular transformation. We propose that nuclear GRC-RNAs represent a novel family of mammalian lncRNAs that might play crucial roles in the cell nucleus.
Collapse
Affiliation(s)
- Ruiping Zheng
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Chemical and Life Sciences Laboratory, 601 South Goodwin Avenue, Urbana, IL 61801, USA
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Zaghloul EM, Madsen AS, Moreno PMD, Oprea II, El-Andaloussi S, Bestas B, Gupta P, Pedersen EB, Lundin KE, Wengel J, Smith CIE. Optimizing anti-gene oligonucleotide 'Zorro-LNA' for improved strand invasion into duplex DNA. Nucleic Acids Res 2010; 39:1142-54. [PMID: 20860997 PMCID: PMC3035455 DOI: 10.1093/nar/gkq835] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Zorro-LNA (Zorro) is a newly developed, oligonucleotide (ON)-based, Z-shaped construct with the potential of specific binding to each strand of duplex DNA. The first-generation Zorros are formed by two hybridized LNA/DNA mixmers (2-ON Zorros) and was hypothesized to strand invade. We have now established a method, which conclusively demonstrates that an LNA ON can strand invade into duplex DNA. To make Zorros smaller in size and easier to design, we synthesized 3′–5′–5′–3′ single-stranded Zorro-LNA (ssZorro) by using both 3′- and 5′-phosphoramidites. With ssZorro, a significantly greater extent and rate of double-strand invasion (DSI) was obtained than with conventional 2-ON Zorros. Introducing hydrophilic PEG-linkers connecting the two strands did not significantly change the rate or extent of DSI as compared to ssZorro with a nucleotide-based linker, while the longest alkyl-chain linker tested (36 carbons) resulted in a very slow DSI. The shortest alkyl-chain linker (3 carbons) did not reduce the extent of DSI of ssZorro, but significantly decreased the DSI rate. Collectively, ssZorro is smaller in size, easier to design and more efficient than conventional 2-ON Zorro in inducing DSI. Analysis of the chemical composition of the linker suggests that it could be of importance for future therapeutic considerations.
Collapse
Affiliation(s)
- Eman M Zaghloul
- Department of Laboratory Medicine, Karolinska Institutet, 141 86 Huddinge, Stockholm, Sweden.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Gillespie MN, Pastukh VM, Ruchko MV. Controlled DNA "damage" and repair in hypoxic signaling. Respir Physiol Neurobiol 2010; 174:244-51. [PMID: 20831905 DOI: 10.1016/j.resp.2010.08.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 08/31/2010] [Indexed: 12/29/2022]
Abstract
Hypoxia, a fundamental stimulus in biology and medicine, uses reactive oxygen species (ROS) as second messengers. A surprising target of hypoxia-generated ROS is specific bases within hypoxic response elements (HREs) of the VEGF and other hypoxia-inducible genes. Oxidative modifications coincide with the onset of mRNA accumulation and are localized to transcriptionally active mono-nucleosomes. The oxidative base modifications are removed by the base excision DNA repair pathway for which one of its components, the bifunctional transcriptional co-activator and DNA endonuclease Ref-1/Ape1, is critical for transcription complex assembly. Mimicking the effect of hypoxia by introducing an abasic site in an oligonucleotide model of the VEGF HRE, altered transcription factor binding, enhanced sequence flexibility, and engendered more robust reporter gene expression. These observations suggest that controlled DNA "damage" and repair, mediated by ROS used as second messengers and critically involving the base excision pathway of DNA repair, respectively, are important for hypoxia-induced transcriptional activation.
Collapse
Affiliation(s)
- Mark N Gillespie
- Department of Pharmacology and Center for Lung Biology, College of Medicine, University of South Alabama, Mobile, AL 36688-0002, United States.
| | | | | |
Collapse
|
38
|
van der Gun BTF, Maluszynska-Hoffman M, Kiss A, Arendzen AJ, Ruiters MHJ, McLaughlin PMJ, Weinhold E, Rots MG. Targeted DNA methylation by a DNA methyltransferase coupled to a triple helix forming oligonucleotide to down-regulate the epithelial cell adhesion molecule. Bioconjug Chem 2010; 21:1239-45. [PMID: 20593890 PMCID: PMC2907751 DOI: 10.1021/bc1000388] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The epithelial cell adhesion molecule (EpCAM) is a membrane glycoprotein that has been identified as a marker of cancer-initiating cells. EpCAM is highly expressed on most carcinomas, and transient silencing of EpCAM expression leads to reduced oncogenic potential. To silence the EpCAM gene in a persistent manner via targeted DNA methylation, a low activity mutant (C141S) of the CpG-specific DNA methyltransferase M.SssI was coupled to a triple-helix-forming oligonucleotide (TFO-C141S) specifically designed for the EpCAM gene. Reporter plasmids encoding the green fluorescent protein under control of different EpCAM promoter fragments were treated with the TFO-C141S conjugate to determine the specificity of targeted DNA methylation in the context of a functional EpCAM promoter. Treatment of the plasmids with TFO-C141S resulted in efficient and specific methylation of the targeted CpG located directly downstream of the triple helix forming site (TFS). No background DNA methylation was observed neither in a 700 bp region of the EpCAM promoter nor in a 400 bp region of the reporter gene downstream of the TFS. Methylation of the target CpG did not have a detectable effect on promoter activity. This study shows that the combination of a specific TFO and a reduced activity methyltransferase variant can be used to target DNA methylation to predetermined sites with high specificity, allowing determination of crucial CpGs for promoter activity.
Collapse
Affiliation(s)
- Bernardina T F van der Gun
- Epigenetic Editing, Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, The Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Zhu X, Liu Y, Yang J, Liang Z, Li G. Gold nanoparticle-based colorimetric assay of single-nucleotide polymorphism of triplex DNA. Biosens Bioelectron 2010; 25:2135-9. [PMID: 20233656 DOI: 10.1016/j.bios.2010.02.017] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/04/2010] [Accepted: 02/18/2010] [Indexed: 11/26/2022]
Abstract
Triplex DNA technology has been considered as an attractive antigen strategy for the treatment of genetic-based diseases. Assay of the formation of triplex is an important part in the development of triplex technology. In this paper, we present a novel method to assay triplex DNA. The strategy is based on the unspecific interaction between single-stranded triplex-forming oligonucleotide (TFO) and negatively charged gold nanoparticles (AuNPs). While triplex is formed, gold nanoparticles will aggregate without the protection of triplex-forming oligonucleotide under a certain concentration of salt. Consequently, the color of the gold nanoparticles will change from red to blue. The formation of triplex DNA and the discrimination of triplex-forming oligonucleotide candidates are thereby easily monitored by the color changes of gold nanoparticles. Also by precisely controlling the working salt concentration, we are allowed to assay single-nucleotide polymorphism of triplex-forming oligonucleotides. Mismatched variants and length variants of triplex-forming oligonucleotides with single-nucleotide or double-nucleotides differences can be well discriminated. This method presented here is simple, fast, and with considerable selectivity, so we expect it will be a promising candidate for the assay of triplex DNA and the screening of appropriate triplex-forming oligonucleotide.
Collapse
Affiliation(s)
- Xiaoli Zhu
- Laboratory of Biosensing Technology, School of Life Science, Shanghai University, Shanghai 200444, PR China
| | | | | | | | | |
Collapse
|
40
|
Genereux JC, Boal AK, Barton JK. DNA-mediated charge transport in redox sensing and signaling. J Am Chem Soc 2010; 132:891-905. [PMID: 20047321 PMCID: PMC2902267 DOI: 10.1021/ja907669c] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The transport of charge through the DNA base-pair stack offers a route to carry out redox chemistry at a distance. Here we describe characteristics of this chemistry that have been elucidated and how this chemistry may be utilized within the cell. The shallow distance dependence associated with these redox reactions permits DNA-mediated signaling over long molecular distances in the genome and facilitates the activation of redox-sensitive transcription factors globally in response to oxidative stress. The long-range funneling of oxidative damage to sites of low oxidation potential in the genome also may provide a means of protection within the cell. Furthermore, the sensitivity of DNA charge transport to perturbations in base-pair stacking, as may arise with base lesions and mismatches, may be used as a route to scan the genome for damage as a first step in DNA repair. Thus, the ability of double-helical DNA in mediating redox chemistry at a distance provides a natural mechanism for redox sensing and signaling in the genome.
Collapse
Affiliation(s)
- Joseph C. Genereux
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125,
| | - Amie K. Boal
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125,
| | - Jacqueline K. Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125,
| |
Collapse
|
41
|
Laible G, Alonso-González L. Gene targeting from laboratory to livestock: current status and emerging concepts. Biotechnol J 2009; 4:1278-92. [PMID: 19606430 DOI: 10.1002/biot.200900006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of methods for cell-mediated transgenesis, based on somatic cell nuclear transfer, provides a tremendous opportunity to shape the genetic make-up of livestock animals in a much more directed approach than traditional animal breeding and selection schemes. Progress in the site-directed modulation of livestock genomes is currently limited by the low efficiencies of gene targeting imposed by the low frequency of homologous recombination and limited proliferative capacity of primary somatic cells that are used to produce transgenic animals. Here we review the current state of the art in the field, discuss the crucial aspects of the methodology and provide an overview of emerging approaches to increase the efficiency of gene targeting in somatic cells.
Collapse
Affiliation(s)
- Götz Laible
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand.
| | | |
Collapse
|
42
|
Jenjaroenpun P, Kuznetsov VA. TTS mapping: integrative WEB tool for analysis of triplex formation target DNA sequences, G-quadruplets and non-protein coding regulatory DNA elements in the human genome. BMC Genomics 2009; 10 Suppl 3:S9. [PMID: 19958507 PMCID: PMC2788396 DOI: 10.1186/1471-2164-10-s3-s9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Background DNA triplexes can naturally occur, co-localize and interact with many other regulatory DNA elements (e.g. G-quadruplex (G4) DNA motifs), specific DNA-binding proteins (e.g. transcription factors (TFs)), and micro-RNA (miRNA) precursors. Specific genome localizations of triplex target DNA sites (TTSs) may cause abnormalities in a double-helix DNA structure and can be directly involved in some human diseases. However, genome localization of specific TTSs, their interconnection with regulatory DNA elements and physiological roles in a cell are poor defined. Therefore, it is important to identify comprehensive and reliable catalogue of specific potential TTSs (pTTSs) and their co-localization patterns with other regulatory DNA elements in the human genome. Results "TTS mapping" database is a web-based search engine developed here, which is aimed to find and annotate pTTSs within a region of interest of the human genome. The engine provides descriptive statistics of pTTSs in a given region and its sequence context. Different annotation tracks of TTS-overlapping gene region(s), G4 motifs, CpG Island, miRNA precursors, miRNA targets, transcription factor binding sites (TFBSs), Single Nucleotide Polymorphisms (SNPs), small nucleolar RNAs (snoRNA), and repeat elements are also mapped based onto a sequence location provided by UCSC genome browser, G4 database http://www.quadruplex.org and several other datasets. The results pages provide links to UCSC genome browser annotation tracks and relative DBs. BLASTN program was included to check the uniqueness of a given pTTS in the human genome. Recombination- and mutation-prone genes (e.g. EVI-1, MYC) were found to be significantly enriched by TTSs and multiple co-occurring with our regulatory DNA elements. TTS mapping reveals that a high-complementary and evolutionarily conserved polypurine and polypyrimidine DNA sequence pair linked by a non-conserved short DNA sequence can form miR-483 transcribed from intron 2 of IGF2 gene and bound double-strand nucleic acid TTSs forming natural triplex structures. Conclusion TTS mapping provides comprehensive visual and analytical tools to help users to find pTTSs, G-quadruplets and other regulatory DNA elements in various genome regions. TTS Mapping not only provides sequence visualization and statistical information, but also integrates knowledge about co-localization TTS with various DNA elements and facilitates that data analysis. In particular, TTS Mapping reveals complex structural-functional regulatory module of gene IGF2 including TF MZF1 binding site and ncRNA precursor mir-483 formed by the high-complementary and evolutionarily conserved polypurine- and polypyrimidine-rich DNA pair. Such ncRNAs capable of forming helical triplex structures with a polypurine strand of a nucleic acid duplexes (DNA or RNA) via Hoogsteen or reverse Hoogsteen hydrogen bonds. Our web tool could be used to discover biologically meaningful genome modules and to optimize experimental design of anti-gene treatment.
Collapse
Affiliation(s)
- Piroon Jenjaroenpun
- Department of Genome and Gene Expression Data Analysis, Bioinformatics Institute, 30 Biopolis str #07-01, Singapore.
| | | |
Collapse
|
43
|
Lundin KE, Simonson OE, Moreno PMD, Zaghloul EM, Oprea II, Svahn MG, Smith CIE. Nanotechnology approaches for gene transfer. Genetica 2009; 137:47-56. [PMID: 19488829 DOI: 10.1007/s10709-009-9372-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Accepted: 05/14/2009] [Indexed: 01/07/2023]
Abstract
In both basic research as well as experimental gene therapy the need to transfer genetic material into a cell is of vital importance. The cellular compartment, which is the target for the genetic material, depends upon application. An siRNA that mediates silencing is preferably delivered to the cytosol while a transgene would need to end up in the nucleus for successful transcription to occur. Furthermore the ability to regulate gene expression has grown substantially since the discovery of RNA interference. In such diverse fields as medical research and agricultural pest control, the capability to alter the genetic output has been a useful tool for pushing the scientific frontiers. This review is focused on nanotechnological approaches to assemble optimised structures of nucleic acid derivatives to facilitate gene delivery as well as promoting down regulation of endogenous genes.
Collapse
Affiliation(s)
- Karin E Lundin
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital, 141 86 Huddinge, Sweden.
| | | | | | | | | | | | | |
Collapse
|
44
|
Belotserkovskii BP, Liu R, Hanawalt PC. Peptide nucleic acid (PNA) binding and its effect on in vitro transcription in friedreich's ataxia triplet repeats. Mol Carcinog 2009; 48:299-308. [PMID: 19306309 DOI: 10.1002/mc.20486] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Peptide nucleic acids (PNAs) are DNA mimics in which peptide-like linkages are substituted for the phosphodiester backbone. Homopyrimidine PNAs can invade double-stranded DNA containing the homologous sequence by displacing the homopyrimidine strand from the DNA duplex and forming a PNA/DNA/PNA triplex with the complementary homopurine strand. Among biologically interesting targets for triplex-forming PNA are (GAA/CTT)(n) repeats. Expansion of these repeats results in partial inhibition of transcription in the frataxin gene, causing Friedreich's ataxia. We have studied PNA binding and its effect on T7 RNA polymerase transcription in vitro for short repeats (n = 3) and for long repeats (n = 39), placed in both possible orientations relative to the T7 promoter such that either the GAA-strand, or the CTT-strand serves as the template for transcription. In all cases PNA bound specifically and efficiently to its target sequence. For the short insert, PNA binding to the template strand caused partial transcription blockage with well-defined sites of RNA product truncation in the region of the PNA-binding sequence, whereas binding to the nontemplate strand did not block transcription. However, PNA binding to long repeats, whether in the template or the nontemplate strand, resulted in a dramatic reduction of the amount of full-length transcription product, although in the case of the nontemplate strand there were no predominant truncation sites. Biological implications of these results are discussed.
Collapse
|
45
|
Reeves GA, Talavera D, Thornton JM. Genome and proteome annotation: organization, interpretation and integration. J R Soc Interface 2009; 6:129-47. [PMID: 19019817 DOI: 10.1098/rsif.2008.0341] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recent years have seen a huge increase in the generation of genomic and proteomic data. This has been due to improvements in current biological methodologies, the development of new experimental techniques and the use of computers as support tools. All these raw data are useless if they cannot be properly analysed, annotated, stored and displayed. Consequently, a vast number of resources have been created to present the data to the wider community. Annotation tools and databases provide the means to disseminate these data and to comprehend their biological importance. This review examines the various aspects of annotation: type, methodology and availability. Moreover, it puts a special interest on novel annotation fields, such as that of phenotypes, and highlights the recent efforts focused on the integrating annotations.
Collapse
Affiliation(s)
- Gabrielle A Reeves
- EMBL-EBI, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK.
| | | | | |
Collapse
|
46
|
Duca M, Vekhoff P, Oussedik K, Halby L, Arimondo PB. The triple helix: 50 years later, the outcome. Nucleic Acids Res 2008; 36:5123-38. [PMID: 18676453 PMCID: PMC2532714 DOI: 10.1093/nar/gkn493] [Citation(s) in RCA: 265] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Triplex-forming oligonucleotides constitute an interesting DNA sequence-specific tool that can be used to target cleaving or cross-linking agents, transcription factors or nucleases to a chosen site on the DNA. They are not only used as biotechnological tools but also to induce modifications on DNA with the aim to control gene expression, such as by site-directed mutagenesis or DNA recombination. Here, we report the state of art of the triplex-based anti-gene strategy 50 years after the discovery of such a structure, and we show the importance of the actual applications and the main challenges that we still have ahead of us.
Collapse
Affiliation(s)
- Maria Duca
- LCMBA CNRS UMR6001, University of Nice-Sophia Antipolis, Parc Valrose, 06108 NICE Cedex 2, France
| | | | | | | | | |
Collapse
|
47
|
Triplex-forming oligonucleotide-orthophenanthroline conjugates for efficient targeted genome modification. Proc Natl Acad Sci U S A 2008; 105:9576-81. [PMID: 18599454 DOI: 10.1073/pnas.0710433105] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The inefficiency of gene modification by homologous recombination can be overcome by the introduction of a double-strand break (DSB) in the target. Engineering the endonucleases needed, however, remains a challenging task that limits widespread application of nuclease-driven gene modification. We report here that conjugates of orthophenanthroline (OP), a DNA cleaving molecule, and triplex-forming oligonucleotides (TFOs), known to bind specific DNA sequences, are synthetic nucleases efficient at stimulating targeted genome modification. We show that in cultured cells, OP-TFO conjugates induce targeted DSBs. An OP-TFO with a unique target was highly efficient, and mutations at the target site were found in approximately 10% of treated cells, including small deletions most likely introduced during DSB repair by nonhomologous end joining. Importantly, we found that when homologous donor DNA was cotransfected, targeted gene modification took place in >1.5% of treated cells. Because triplex-forming sequences are frequent in human and mouse genes, OP-TFO conjugates therefore constitute an important class of site-specific nucleases for targeted gene modification. Harnessing DNA-damaging molecules to predetermined genomic sites, as achieved here, should also provide inroads into mechanisms of DNA repair and cancer.
Collapse
|
48
|
Benfield AP, Macleod MC, Liu Y, Wu Q, Wensel TG, Vasquez KM. Targeted generation of DNA strand breaks using pyrene-conjugated triplex-forming oligonucleotides. Biochemistry 2008; 47:6279-88. [PMID: 18473480 DOI: 10.1021/bi7024029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gene targeting by triplex-forming oligonucleotides (TFOs) has proven useful for gene modulation in vivo. Photoreactive molecules have been conjugated to TFOs to direct sequence-specific damage in double-stranded DNA. However, the photoproducts are often repaired efficiently in cells. This limitation has led to the search for sequence-specific photoreactive reagents that can produce more genotoxic lesions. Here we demonstrate that photoactivated pyrene-conjugated TFOs (pyr-TFOs) induce DNA strand breaks near the pyrene moiety with remarkably high efficiency and also produce covalent pyrene-DNA adducts. Free radical scavenging experiments demonstrated a role for singlet oxygen activated by the singlet excited state of pyrene in the mechanism of pyr-TFO-induced DNA damage. In cultured mammalian cells, the effect of photoactivated pyr-TFO-directed DNA damage was to induce mutations, in the form of deletions, approximately 7-fold over background levels, at the targeted site. Thus, pyr-TFOs represent a potentially powerful new tool for directing DNA strand breaks to specific chromosomal locations for biotechnological and potential clinical applications.
Collapse
Affiliation(s)
- Aaron P Benfield
- Department of Carcinogenesis, The University of Texas M. D. Anderson Cancer Center, Science Park-Research Division, Smithville, Texas 78957, USA
| | | | | | | | | | | |
Collapse
|
49
|
Paramasivam M, Cogoi S, Filichev VV, Bomholt N, Pedersen EB, Xodo LE. Purine twisted-intercalating nucleic acids: a new class of anti-gene molecules resistant to potassium-induced aggregation. Nucleic Acids Res 2008; 36:3494-507. [PMID: 18456705 PMCID: PMC2425464 DOI: 10.1093/nar/gkn242] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Sequence-specific targeting of genomic DNA by triplex-forming oligonucleotides (TFOs) is a promising strategy to modulate in vivo gene expression. Triplex formation involving G-rich oligonucleotides as third strand is, however, strongly inhibited by potassium-induced TFO self-association into G-quartet structures. We report here that G-rich TFOs with bulge insertions of (R)-1-O-[4-(1-pyrenylethynyl)-phenylmethyl] glycerol (called twisted intercalating nucleic acids, TINA) show a much lower tendency to aggregate in potassium than wild-type analogues do. We designed purine-motif TINA–TFOs for binding to a regulatory polypurine-polypyrimidine (pur/pyr) motif present in the promoter of the KRAS proto-oncogene. The binding of TINA–TFOs to the KRAS target has been analysed by electrophoresis mobility shift assays and DNase I footprinting experiments. We discovered that in the presence of potassium the wild-type TFOs did not bind to the KRAS target, differently from the TINA analogues, whose binding was observed up to 140 mM KCl. The designed TINA–TFOs were found to abrogate the formation of a DNA–protein complex at the pur/pyr site and to down-regulate the transcription of CAT driven by the murine KRAS promoter. Molecular modelling of the DNA/TINA–TFO triplexes are also reported. This study provides a new and promising approach to create TFOs to target in vivo the genome.
Collapse
|
50
|
Simon P, Cannata F, Concordet JP, Giovannangeli C. Targeting DNA with triplex-forming oligonucleotides to modify gene sequence. Biochimie 2008; 90:1109-16. [PMID: 18460344 DOI: 10.1016/j.biochi.2008.04.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Accepted: 04/14/2008] [Indexed: 12/19/2022]
Abstract
Molecules that interact with DNA in a sequence-specific manner are attractive tools for manipulating gene sequence and expression. For example, triplex-forming oligonucleotides (TFOs), which bind to oligopyrimidine.oligopurine sequences via Hoogsteen hydrogen bonds, have been used to inhibit gene expression at the DNA level as well as to induce targeted mutagenesis in model systems. Recent advances in using oligonucleotides and analogs to target DNA in a sequence-specific manner will be discussed. In particular, chemical modification of TFOs has been used to improve binding to chromosomal target sequences in living cells. Various oligonucleotide analogs have also been found to expand the range of sequences amenable to manipulation, including so-called "Zorro" locked nucleic acids (LNAs) and pseudo-complementary peptide nucleic acids (pcPNAs). Finally, we will examine the potential of TFOs for directing targeted gene sequence modification and propose that synthetic nucleases, based on conjugation of sequence-specific DNA ligands to DNA damaging molecules, are a promising alternative to protein-based endonucleases for targeted gene sequence modification.
Collapse
Affiliation(s)
- Philippe Simon
- Laboratoire de Biophysique, Muséum National d'Histoire Naturelle, USM 503, 43 rue Cuvier, 75005 Paris, France
| | | | | | | |
Collapse
|