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Adhikari SP, Karmakar S, Hrdlicka PJ. Nicked Invader probes: multistranded and sequence-unrestricted recognition of double-stranded DNA. Org Biomol Chem 2022; 20:1019-1030. [PMID: 34874037 PMCID: PMC8810728 DOI: 10.1039/d1ob02019f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Major efforts have been devoted to the development of constructs that enable sequence-specific recognition of double-stranded (ds) DNA, fueled by the promise for enabling tools for applications in molecular biology, diagnostics, and medicine. Towards this end, we have previously introduced Invader probes, i.e., short DNA duplexes with +1 interstrand zipper arrangements of intercalator-functionalized nucleotides. The individual strands of these labile probes display high affinity towards complementary DNA (cDNA), which drives sequence-unrestricted dsDNA-recognition. However, recognition of long targets is challenging due to the high stability of the corresponding probes. To address this, we recently introduced toehold Invader probes, i.e., Invader probes with 5'-single-stranded overhangs. The toehold architecture allows for shorter double-stranded segments to be used, which facilitates probe dissociation and dsDNA-recognition. As an extension thereof, we here report the biophysical and dsDNA-targeting properties of nicked Invader probes. In this probe architecture, the single-stranded overhangs of toehold Invader probes are hybridized to short intercalator-modified auxiliary strands, leading to formation of additional labile segments. The extra binding potential from the auxiliary strands imparts nicked Invader probes with greater dsDNA-affinity than the corresponding toehold or blunt-ended probes. Recognition of chromosomal DNA targets, refractory to recognition by conventional Invader probes, is demonstrated for nicked Invader probes in the context of non-denaturing FISH experiments, which highlights their utility as dsDNA-targeting tools.
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Affiliation(s)
- Shiva P Adhikari
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
| | - Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
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2
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Adhikari SP, Vukelich P, Guenther DC, Karmakar S, Hrdlicka PJ. Recognition of double-stranded DNA using LNA-modified toehold Invader probes. Org Biomol Chem 2021; 19:9276-9290. [PMID: 34657934 PMCID: PMC8625219 DOI: 10.1039/d1ob01888d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Development of molecules capable of binding to specific sequences of double-stranded (ds) DNA continues to attract considerable interest, as this may yield useful tools for applications in life science, biotechnology, and medicine. We have previously demonstrated sequence-unrestricted of dsDNA using Invader probes, i.e., DNA duplexes that are energetically activated through incorporation of +1 interstrand zipper arrangements of O2'-intercalator-functionalized RNA monomers. Nonetheless, recognition of extended dsDNA target regions remains challenging due to the high stability of the corresponding probes. To address this, we introduce toehold Invader probes, i.e., Invader probes with 5'-single-stranded overhangs. This design provides access to probes with shortened double-stranded segments, which facilitates probe denaturation. The single-stranded overhangs can, furthermore, be modified with affinity-enhancing modifications like LNA (locked nucleic acid) monomers to additionally increase target affinity. Herein, we report the biophysical and dsDNA-targeting properties of different toehold Invader designs and compare them to conventional Invader probes. LNA-modified toehold Invader probes display promising recognition characteristics, including greatly improved affinity to dsDNA, excellent binding specificity, and fast recognition kinetics, which enabled recognition of chromosomal DNA targets that have proven refractory to recognition by conventional Invader probes. Thus, toehold Invader probes represent another step toward a robust, oligonucleotide-based approach for sequence-unrestricted dsDNA-recognition.
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Affiliation(s)
- Shiva P Adhikari
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
| | - Philip Vukelich
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
| | - Dale C Guenther
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
| | - Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
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3
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Topham CM, Smith JC. Peptide nucleic acid Hoogsteen strand linker design for major groove recognition of DNA thymine bases. J Comput Aided Mol Des 2021; 35:355-369. [PMID: 33624202 DOI: 10.1007/s10822-021-00375-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 02/03/2021] [Indexed: 10/22/2022]
Abstract
Sequence-specific targeting of double-stranded DNA and non-coding RNA via triple-helix-forming peptide nucleic acids (PNAs) has attracted considerable attention in therapeutic, diagnostic and nanotechnological fields. An E-base (3-oxo-2,3-dihydropyridazine), attached to the polyamide backbone of a PNA Hoogsteen strand by a side-chain linker molecule, is typically used in the hydrogen bond recognition of the 4-oxo group of thymine and uracil nucleic acid bases in the major groove. We report on the application of quantum chemical computational methods, in conjunction with spatial constraints derived from the experimental structure of a homopyrimidine PNA·DNA-PNA hetero-triplex, to investigate the influence of linker flexibility on binding interactions of the E-base with thymine and uracil bases in geometry-optimised model systems. Hydrogen bond formation between the N2 E-base atom and target pyrimidine base 4-oxo groups in model systems containing a β-alanine linker (J Am Chem Soc 119:11116, 1997) was found to incur significant internal strain energy and the potential disruption of intra-stand aromatic base stacking interactions in an oligomeric context. In geometry-optimised model systems containing a 3-trans olefin linker (Bioorg Med Chem Lett 14:1551, 2004) the E-base swung out away from the target pyrimidine bases into the solvent. These findings are in qualitative agreement with calorimetric measurements in hybridisation experiments at T-A and U-A inversion sites. In contrast, calculations on a novel 2-cis olefin linker design indicate that it could permit simultaneous E-base hydrogen bonding with the thymine 4-oxo group, circumvention and solvent screening of the thymine 5-methyl group, and maintenance of triplex intra-stand base stacking interactions.
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Affiliation(s)
- Christopher M Topham
- Molecular Forces Consulting, 24 Avenue Jacques Besse, 81500, Lavaur, France.
- Computational Molecular Biophysics, IWR Der Universität Heidelberg, Im Neuenheimer Feld 368, 69120, Heidelberg, Germany.
- Center for Molecular Biophysics, University of Tennessee / Oak Ridge National Laboratory, P.O.Box 2008, Oak Ridge, TN, 37831-6309, USA.
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN, 37996, USA.
| | - Jeremy C Smith
- Computational Molecular Biophysics, IWR Der Universität Heidelberg, Im Neuenheimer Feld 368, 69120, Heidelberg, Germany
- Center for Molecular Biophysics, University of Tennessee / Oak Ridge National Laboratory, P.O.Box 2008, Oak Ridge, TN, 37831-6309, USA
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN, 37996, USA
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Guenther DC, Emehiser RG, Inskeep A, Karmakar S, Hrdlicka PJ. Impact of non-nucleotidic bulges on recognition of mixed-sequence dsDNA by pyrene-functionalized Invader probes. Org Biomol Chem 2020; 18:4645-4655. [PMID: 32520054 PMCID: PMC7340116 DOI: 10.1039/d0ob01052a] [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] [Indexed: 11/21/2022]
Abstract
Invader probes, i.e., DNA duplexes modified with +1 interstrand zippers of intercalator-functionalized nucleotides like 2'-O-(pyren-1-yl)methyl-RNA monomers, are energetically activated for sequence-unrestricted recognition of double-stranded DNA (dsDNA) as they are engineered to violate the neighbor exclusion principle, while displaying high affinity towards complementary DNA sequences. The impact on Invader-mediated dsDNA-recognition upon additional modification with different non-nucleotidic bulges is studied herein, based on the hypothesis that bulge-containing Invader probes will display additionally disrupted base-stacking, more extensive denaturation, and improved dsDNA-recognition efficiency. Indeed, Invader probes featuring a single central large bulge - e.g., a nonyl (C9) monomer - display improved recognition of model DNA hairpin targets vis-à-vis conventional Invader probes (C50 values ∼1.5 μM vs. ∼3.9 μM). In contrast, probes with two opposing central bulges display less favorable binding characteristics. Remarkably, C9-modified Invader probes display perfect discrimination between fully complementary dsDNA and dsDNA differing in only one of eighteen base-pairs, underscoring the high binding specificity of double-stranded probes. Cy3-labeled bulge-containing Invader probes are demonstrated to signal the presence of gender-specific DNA sequences in fluorescent in situ hybridization assays (FISH) performed under non-denaturing conditions, highlighting one potential application of dsDNA-targeting Invader probes.
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Affiliation(s)
- Dale C Guenther
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
| | | | - Allison Inskeep
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
| | - Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
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Lu Z, Paolella BR, Truex NL, Loftis AR, Liao X, Rabideau AE, Brown MS, Busanovich J, Beroukhim R, Pentelute BL. Targeting Cancer Gene Dependencies with Anthrax-Mediated Delivery of Peptide Nucleic Acids. ACS Chem Biol 2020; 15:1358-1369. [PMID: 32348107 PMCID: PMC7521945 DOI: 10.1021/acschembio.9b01027] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Antisense oligonucleotide therapies are important cancer treatments, which can suppress genes in cancer cells that are critical for cell survival. SF3B1 has recently emerged as a promising gene target that encodes a key splicing factor in the SF3B protein complex. Over 10% of cancers have lost one or more copies of the SF3B1 gene, rendering these cancers vulnerable after further suppression. SF3B1 is just one example of a CYCLOPS (Copy-number alterations Yielding Cancer Liabilities Owing to Partial losS) gene, but over 120 additional candidate CYCLOPS genes are known. Antisense oligonucleotide therapies for cancer offer the promise of effective suppression for CYCLOPS genes, but developing these treatments is difficult due to their limited permeability into cells and poor cytosolic stability. Here, we develop an effective approach to suppress CYCLOPS genes by delivering antisense peptide nucleic acids (PNAs) into the cytosol of cancer cells. We achieve efficient cytosolic PNA delivery with the two main nontoxic components of the anthrax toxin: protective antigen (PA) and the 263-residue N-terminal domain of lethal factor (LFN). Sortase-mediated ligation readily enables the conjugation of PNAs to the C terminus of the LFN protein. LFN and PA work together in concert to translocate PNAs into the cytosol of mammalian cells. Antisense SF3B1 PNAs delivered with the LFN/PA system suppress the SF3B1 gene and decrease cell viability, particularly of cancer cells with partial copy-number loss of SF3B1. Moreover, antisense SF3B1 PNAs delivered with a HER2-binding PA variant selectively target cancer cells that overexpress the HER2 cell receptor, demonstrating receptor-specific targeting of cancer cells. Taken together, our efforts illustrate how PA-mediated delivery of PNAs provides an effective and general approach for delivering antisense PNA therapeutics and for targeting gene dependencies in cancer.
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Affiliation(s)
- Zeyu Lu
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Brenton R. Paolella
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02139, USA
| | - Nicholas L. Truex
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Alexander R. Loftis
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Xiaoli Liao
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Amy E. Rabideau
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Meredith S. Brown
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02139, USA
| | - John Busanovich
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02139, USA
| | - Rameen Beroukhim
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02139, USA
| | - Bradley L. Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
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Emehiser RG, Hall E, Guenther DC, Karmakar S, Hrdlicka PJ. Head-to-head comparison of LNA, MPγPNA, INA and Invader probes targeting mixed-sequence double-stranded DNA. Org Biomol Chem 2020; 18:56-65. [PMID: 31681928 DOI: 10.1039/c9ob02111f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Four probe chemistries are characterized and compared with respect to thermal denaturation temperatures (Tms), thermodynamic parameters associated with duplex formation, and recognition of mixed-sequence double-stranded (ds) DNA targets: (i) oligodeoxyribonucleotides (ONs) modified with Locked Nucleic Acid (LNA) monomers, (ii) MPγPNAs, i.e., single-stranded peptide nucleic acid (PNA) probes that are functionalized at the γ-position with (R)-diethylene glycol (mini-PEG, MP) moieties, (iii) Invader probes, i.e., DNA duplexes modified with +1 interstrand zipper arrangements of 2'-O-(pyren-1-yl)methyl-RNA monomers, and (iv) intercalating nucleic acids (INAs), i.e., DNA duplexes with opposing insertions of 1-O-(1-pyrenylmethyl)glycerol bulges. Invader and INA probes, which are designed to violate the nearest-neighbor exclusion principle, denature readily, whereas the individual probe strands display exceptionally high affinity towards complementary DNA (cDNA) as indicated by increases in Tms of up to 8 °C per modification. Optimized Invader and INA probes enable efficient and highly specific recognition of mixed-sequence dsDNA targets with self-complementary regions (C50 = 30-50 nM), whereas recognition is less efficient with LNA-modified ONs and fully modified MPγPNAs due to lower cDNA affinity (LNA) and a proclivity for dimerization (LNA and MPγPNA). A Cy3-labeled Invader probe is shown to stain telomeric DNA of individual chromosomes in metaphasic spreads under non-denaturing conditions with excellent specificity.
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Emehiser RG, Hrdlicka PJ. Chimeric γPNA-Invader probes: using intercalator-functionalized oligonucleotides to enhance the DNA-targeting properties of γPNA. Org Biomol Chem 2020; 18:1359-1368. [PMID: 31984413 DOI: 10.1039/c9ob02726b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Gamma peptide nucleic acids (γPNAs), i.e., single-stranded PNA strands that are modified at the γ-position with (R)-diethylene glycol, and Invader probes, i.e., DNA duplexes with +1 interstrand zipper arrangements of 2'-O-(pyren-1-yl)methyl-RNA monomers, are two types of nucleic acid mimics that are showing promise for sequence-unrestricted recognition of double-stranded (ds) DNA targets. We recently demonstrated that recognition of dsDNA targets with self-complementary regions is challenging for single-stranded high-affinity probes like γPNAs due to their proclivity for secondary structure formation, but not so for Invader probes, which are engineered to form readily denaturing duplexes irrespective of the target sequence context. In the present study, we describe an approach that mitigates these limitations and improves the dsDNA-recognition properties of γPNAs in partially self-complementary target contexts. Chimeric probes between γPNAs and individual Invader strands are shown to form metastable duplexes that (i) are energetically activated for recognition of complementary mixed-sequence dsDNA target regions, (ii) reduce γPNA dimerization, and (iii) substantially improve the fidelity of the dsDNA-recognition process. Chimeric γPNA-Invader probes are characterized with respect to thermal denaturation properties, thermodynamic parameters associated with duplex formation, UV-Vis and fluorescence trends to establish pyrene binding modes, and dsDNA-recognition properties using DNA hairpin model targets.
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8
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Adhikari SP, Emehiser RG, Karmakar S, Hrdlicka PJ. Recognition of mixed-sequence DNA targets using spermine-modified Invader probes. Org Biomol Chem 2020; 17:8795-8799. [PMID: 31469146 DOI: 10.1039/c9ob01686d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Double-stranded oligodeoxyribonucleotides with +1 interstrand zipper arrangements of 2'-O-(pyren-1-yl)methyl-RNA monomers are additionally activated for highly specific recognition of mixed-sequence DNA targets upon incorporation of non-nucleotidic spermine bulges.
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Affiliation(s)
- Shiva P Adhikari
- Department of Chemistry, University of Idaho, 875 Perimeter Drive MS2343, Moscow, ID 83844-2343, USA.
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9
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Indumathi K, Abiram A, Praveena G. Effect of peptidic backbone on the nucleic acid dimeric strands. Mol Phys 2020. [DOI: 10.1080/00268976.2019.1584682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- K. Indumathi
- Department of Physics, PSGR Krishnammal College for Women, Coimbatore, India
| | - A. Abiram
- Department of Physics, Karunya Institute of Technology and Sciences, Coimbatore, India
| | - G. Praveena
- Department of Physics, PSGR Krishnammal College for Women, Coimbatore, India
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10
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Scoles DR, Pulst SM. Antisense therapies for movement disorders. Mov Disord 2019; 34:1112-1119. [PMID: 31283857 DOI: 10.1002/mds.27782] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 05/10/2019] [Accepted: 06/06/2019] [Indexed: 12/12/2022] Open
Abstract
Currently, few disease-modifying therapies exist for degenerative movement disorders. Antisense oligonucleotides are small DNA oligonucleotides, usually encompassing ∼20 base pairs, that can potentially target any messenger RNA of interest. Antisense oligonucleotides often contain modifications to the phosphate backbone, the sugar moiety, and the nucleotide base. The development of antisense oligonucleotide therapies spinal muscular atrophy and Duchenne muscular dystrophy suggest potentially wide-ranging therapeutic applications for antisense oligonucleotides in neurology. Successes with these two diseases have heightened interest in academia and the pharmaceutical industry to develop antisense oligonucleotides for several movement disorders, including, spinocerebellar ataxias, Huntington's disease, and Parkinson's disease. Compared to small molecules, antisense oligonucleotide-based therapies have an advantage because the target disease gene sequence is the immediate path to identifying the therapeutically effective complementary antisense oligonucleotide. In this review we describe the different types of antisense oligonucleotide chemistries and their potential use for the treatment of human movement disorders. © 2019 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Daniel R Scoles
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, 5th Floor, Salt Lake City, Utah, USA
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Scoles DR, Minikel EV, Pulst SM. Antisense oligonucleotides: A primer. NEUROLOGY-GENETICS 2019; 5:e323. [PMID: 31119194 PMCID: PMC6501637 DOI: 10.1212/nxg.0000000000000323] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Abstract
There are few disease-modifying therapeutics for neurodegenerative diseases, but successes on the development of antisense oligonucleotide (ASO) therapeutics for spinal muscular atrophy and Duchenne muscular dystrophy predict a robust future for ASOs in medicine. Indeed, existing pipelines for the development of ASO therapies for spinocerebellar ataxias, Huntington disease, Alzheimer disease, amyotrophic lateral sclerosis, Parkinson disease, and others, and increased focus by the pharmaceutical industry on ASO development, strengthen the outlook for using ASOs for neurodegenerative diseases. Perhaps the most significant advantage to ASO therapeutics over other small molecule approaches is that acquisition of the target sequence provides immediate knowledge of putative complementary oligonucleotide therapeutics. In this review, we describe the various types of ASOs, how they are used therapeutically, and the present efforts to develop new ASO therapies that will contribute to a forthcoming toolkit for treating multiple neurodegenerative diseases.
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Affiliation(s)
- Daniel R Scoles
- Department of Neurology (D.R.S., S.M.P.), University of Utah, Salt Lake City, UT; and Center for the Science of Therapeutics (E.V.M.), Broad Institute of MIT and Harvard, Cambridge, MA
| | - Eric V Minikel
- Department of Neurology (D.R.S., S.M.P.), University of Utah, Salt Lake City, UT; and Center for the Science of Therapeutics (E.V.M.), Broad Institute of MIT and Harvard, Cambridge, MA
| | - Stefan M Pulst
- Department of Neurology (D.R.S., S.M.P.), University of Utah, Salt Lake City, UT; and Center for the Science of Therapeutics (E.V.M.), Broad Institute of MIT and Harvard, Cambridge, MA
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Karmakar S, Horrocks T, Gibbons BC, Guenther DC, Emehiser R, Hrdlicka PJ. Synthesis and biophysical characterization of oligonucleotides modified with O2'-alkylated RNA monomers featuring substituted pyrene moieties. Org Biomol Chem 2019; 17:609-621. [PMID: 30575837 DOI: 10.1039/c8ob02764a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Over the past three decades, a wide range of pyrene-functionalized oligonucleotides have been developed and explored for potential applications in material science and nucleic acid diagnostics. Our efforts have focused on their possible use as components of Invader probes, i.e., DNA duplexes with +1 interstrand zipper arrangements of intercalator-functionalized nucleotides. We have previously demonstrated that Invader probes based on 2'-O-(pyren-1-yl)methyl-RNA monomers are energetically activated for sequence-unrestricted recognition of chromosomal DNA targets under non-denaturing conditions. As part of ongoing efforts towards delineating structure-property relationships and optimizing Invader probes, we report the synthesis and biophysical characterization of oligodeoxyribonucleotides (ONs) modified with 2'-O-(7-neo-pentylpyren-1-yl)methyl-uridine monomer V and 2'-O-(7-tert-butyl-1-methoxypyren-5-yl)methyl-uridine monomer Y. ONs modified with monomer V display increased DNA affinity (ΔTm up to +10.5 °C), while Y-modified ONs display lower DNA affinity and up to 22-fold increases in fluorescence emission upon RNA binding. Although these monomers display limited potential as building blocks for Invader probes, their photophysical properties render them of interest for diagnostic RNA-targeting applications.
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Affiliation(s)
- Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
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Yang H, Xi W. Nucleobase-Containing Polymers: Structure, Synthesis, and Applications. Polymers (Basel) 2017; 9:E666. [PMID: 30965964 PMCID: PMC6418729 DOI: 10.3390/polym9120666] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 11/25/2017] [Accepted: 11/27/2017] [Indexed: 01/07/2023] Open
Abstract
Nucleobase interactions play a fundamental role in biological functions, including transcription and translation. Natural nucleic acids like DNA are also widely implemented in material realm such as DNA guided self-assembly of nanomaterials. Inspired by that, polymer chemists have contributed phenomenal endeavors to mimic both the structures and functions of natural nucleic acids in synthetic polymers. Similar sequence-dependent responses were observed and employed in the self-assembly of these nucleobase-containing polymers. Here, the structures, synthetic approaches, and applications of nucleobase-containing polymers are highlighted and a brief look is taken at the future development of these polymers.
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Affiliation(s)
- Haitao Yang
- School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China.
| | - Weixian Xi
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, CA 90095, USA.
- Department of Orthopedic Surgery, University of California Los Angeles, Los Angeles, CA 90095, USA.
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Karmakar S, Guenther DC, Gibbons BC, Hrdlicka PJ. Recognition of mixed-sequence DNA using double-stranded probes with interstrand zipper arrangements of O2'-triphenylene- and coronene-functionalized RNA monomers. Org Biomol Chem 2017; 15:9362-9371. [PMID: 29090304 PMCID: PMC5700769 DOI: 10.1039/c7ob01920c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Development of hybridization-based probes that enable recognition of specific mixed-sequence double-stranded DNA (dsDNA) regions is of considerable interest due to their potential applications in molecular biology, biotechnology, and medicine. We have recently demonstrated that nucleic acid duplexes with +1 interstrand zipper arrangements of intercalator-functionalized nucleotides such as 2'-O-(pyren-1-yl)methyl RNA monomers are inherently activated for recognition of mixed-sequence dsDNA targets, including chromosomal DNA. In the present work, we follow up on our previous structure-activity relationship studies and explore if the dsDNA-recognition efficiency of these so-called Invader probes can be improved by using larger intercalators than pyrene. Oligodeoxyribonucleotides modified with 2'-O-(triphenylen-2-yl)methyl-uridine monomer X and 2'-O-(coronen-1-yl)methyl-uridine monomer Z form extraordinarily stabilized duplexes with complementary DNA (ΔTm's per modification of up to 13 °C and 20 °C, respectively). Invader probes based on X- and Z-monomers are shown to recognize model dsDNA targets with exceptional binding specificity, but are less efficient than reference probes modified with 2'-O-(pyren-1-yl)methyl-uridine monomer Y. The insight from this study will inform further optimization of Invader probes.
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Affiliation(s)
- Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA.
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Li Z, Zhang Y, Zhu D, Li S, Yu X, Zhao Y, Ouyang X, Xie Z, Li L. Transporting carriers for intracellular targeting delivery via non-endocytic uptake pathways. Drug Deliv 2017; 24:45-55. [PMID: 29069996 PMCID: PMC8812582 DOI: 10.1080/10717544.2017.1391889] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
To develop novel therapies for clinical treatments, it increasingly depends on sophisticated delivery systems that facilitate the drugs entry into targeting cells. Profound understanding of cellular uptake routes for transporting carriers promotes the optimization of performance in drug delivery systems. Although endocytic pathway is the most important part of cellular uptake routes for many delivery systems, it suffers the trouble of enzymatic degradation of transporting carriers trapped in endosomes/lysosomes. Therefore, it is desirable to develop alternative transporting methods for delivery systems via non-endocytic pathways to achieve more effective intracellular delivery. In this review, we summarize the literature exploring transporting carriers that mediate intracellular delivery via non-endocytic pathways to present the current research status in this field. Cell-penetrating peptides, pH (low) insertion peptides, and nanoparticles are categorized to exhibit their ability to directly transport various cargos into cytoplasm via non-endocytic uptake in different cell lines. It is hoped that this review can spur the interesting on development of drug delivery systems via non-endocytic uptake pathway.
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Affiliation(s)
- Zuhong Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Yanhong Zhang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Danhua Zhu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Shuiqing Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Xiaopeng Yu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Yalei Zhao
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Xiaoxi Ouyang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Zhongyang Xie
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
| | - Lanjuan Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Centre for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
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16
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Genomic targeting of epigenetic probes using a chemically tailored Cas9 system. Proc Natl Acad Sci U S A 2017; 114:681-686. [PMID: 28069948 DOI: 10.1073/pnas.1615723114] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent advances in the field of programmable DNA-binding proteins have led to the development of facile methods for genomic localization of genetically encodable entities. Despite the extensive utility of these tools, locus-specific delivery of synthetic molecules remains limited by a lack of adequate technologies. Here we combine the flexibility of chemical synthesis with the specificity of a programmable DNA-binding protein by using protein trans-splicing to ligate synthetic elements to a nuclease-deficient Cas9 (dCas9) in vitro and subsequently deliver the dCas9 cargo to live cells. The versatility of this technology is demonstrated by delivering dCas9 fusions that include either the small-molecule bromodomain and extra-terminal family bromodomain inhibitor JQ1 or a peptide-based PRC1 chromodomain ligand, which are capable of recruiting endogenous copies of their cognate binding partners to targeted genomic binding sites. We expect that this technology will allow for the genomic localization of a wide array of small molecules and modified proteinaceous materials.
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17
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Anderson BA, Hrdlicka PJ. Merging Two Strategies for Mixed-Sequence Recognition of Double-Stranded DNA: Pseudocomplementary Invader Probes. J Org Chem 2016; 81:3335-46. [PMID: 26998918 PMCID: PMC4836393 DOI: 10.1021/acs.joc.6b00369] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
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The development of molecular strategies
that enable recognition
of specific double-stranded DNA (dsDNA) regions has been a longstanding
goal as evidenced by the emergence of triplex-forming oligonucleotides,
peptide nucleic acids (PNAs), minor groove binding polyamides, and—more
recently—engineered proteins such as CRISPR/Cas9. Despite this
progress, an unmet need remains for simple hybridization-based probes
that recognize specific mixed-sequence dsDNA regions under physiological
conditions. Herein, we introduce pseudocomplementary Invader probes as a step in this direction. These double-stranded probes
are chimeras between pseudocomplementary DNA (pcDNA) and Invader probes,
which are activated for mixed-sequence dsDNA-recognition through the
introduction of pseudocomplementary base pairs comprised of 2-thiothymine
and 2,6-diaminopurine, and +1 interstrand zipper arrangements of intercalator-functionalized
nucleotides, respectively. We demonstrate that certain pseudocomplementary
Invader probe designs result in very efficient and specific recognition
of model dsDNA targets in buffers of high ionic strength. These chimeric
probes, therefore, present themselves as a promising strategy for
mixed-sequence recognition of dsDNA targets for applications in molecular
biology and nucleic acid diagnostics.
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Affiliation(s)
- Brooke A Anderson
- Department of Chemistry, University of Idaho , Moscow, Idaho 83844-2343, United States
| | - Patrick J Hrdlicka
- Department of Chemistry, University of Idaho , Moscow, Idaho 83844-2343, United States
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18
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Ultra-sensitive droplet digital PCR for detecting a low-prevalence somatic GNAQ mutation in Sturge-Weber syndrome. Sci Rep 2016; 6:22985. [PMID: 26957145 PMCID: PMC4783707 DOI: 10.1038/srep22985] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/25/2016] [Indexed: 01/19/2023] Open
Abstract
Droplet digital PCR (ddPCR), a method for measuring target nucleic acid sequence quantity, is useful for determining somatic mutation rates using TaqMan probes. In this study, the detection limit of copy numbers of test DNA by ddPCR was determined based on Poisson distribution. Peptide nucleic acid (PNA), which strongly hybridises to target lesions, can inhibit target amplification by PCR. Therefore, by combination of PCR with PNA and ddPCR (PNA-ddPCR), the detection limit could be lowered. We reanalysed a somatic GNAQ mutation (c.548G > A) in patients with Sturge-Weber syndrome (SWS) using ddPCR and PNA-ddPCR. Importantly, among three patients previously found to be mutation negative by next-generation sequencing, two patients had the GNAQ mutation with a mutant allele frequency of less than 1%. Furthermore, we were able to find the same mutation in blood leukocyte or saliva DNA derived from four out of 40 SWS patients. Vascular anomalies and blood leukocytes originate from endothelial cells and haemangioblasts, respectively, which are both of mesodermal origin. Therefore, blood leukocytes may harbour the GNAQ mutation, depending on the time when the somatic mutation is acquired. These data suggest the possibility of diagnosis using blood DNA in some patients with SWS.
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19
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Portnoy V, Lin SHS, Li KH, Burlingame A, Hu ZH, Li H, Li LC. saRNA-guided Ago2 targets the RITA complex to promoters to stimulate transcription. Cell Res 2016; 26:320-35. [PMID: 26902284 PMCID: PMC4783471 DOI: 10.1038/cr.2016.22] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 10/22/2015] [Accepted: 01/12/2016] [Indexed: 12/21/2022] Open
Abstract
Small activating RNAs (saRNAs) targeting specific promoter regions are able to stimulate gene expression at the transcriptional level, a phenomenon known as RNA activation (RNAa). It is known that RNAa depends on Ago2 and is associated with epigenetic changes at the target promoters. However, the precise molecular mechanism of RNAa remains elusive. Using human CDKN1A (p21) as a model gene, we characterized the molecular nature of RNAa. We show that saRNAs guide Ago2 to and associate with target promoters. saRNA-loaded Ago2 facilitates the assembly of an RNA-induced transcriptional activation (RITA) complex, which, in addition to saRNA-Ago2 complex, includes RHA and CTR9, the latter being a component of the PAF1 complex. RITA interacts with RNA polymerase II to stimulate transcription initiation and productive elongation, accompanied by monoubiquitination of histone 2B. Our results establish the existence of a cellular RNA-guided genome-targeting and transcriptional activation mechanism and provide important new mechanistic insights into the RNAa process.
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Affiliation(s)
- Victoria Portnoy
- Department of Urology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94158, USA
| | - Szu Hua Sharon Lin
- Department of Urology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94158, USA
| | - Kathy H Li
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Alma Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Zheng-Hui Hu
- Department of Urology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94158, USA
| | - Hao Li
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Long-Cheng Li
- Department of Urology and Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94158, USA.,Laboratory of Molecular Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing 100730, China
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20
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Zhao XL, Chen BC, Han JC, Wei L, Pan XB. Delivery of cell-penetrating peptide-peptide nucleic acid conjugates by assembly on an oligonucleotide scaffold. Sci Rep 2015; 5:17640. [PMID: 26612536 PMCID: PMC4661726 DOI: 10.1038/srep17640] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 11/03/2015] [Indexed: 01/01/2023] Open
Abstract
Delivery to intracellular target sites is still one of the main obstacles in the development of peptide nucleic acids (PNAs) as antisense-antigene therapeutics. Here, we designed a self-assembled oligonucleotide scaffold that included a central complementary region for self-assembly and lateral regions complementing the PNAs. Assembly of cell-penetrating peptide (CPP)-PNAs on the scaffold significantly promoted endocytosis of PNAs by at least 10-fold in cell cultures, particularly for scaffolds in which the central complementary region was assembled by poly(guanine) and poly(cytosine). The antisense activity of CPP-PNAs increased by assembly on the scaffold and was further enhanced after co-assembly with endosomolytic peptide (EP)-PNA. This synergistic effect was also observed following the assembly of antigene CPP-PNAs\EP-PNAs on the scaffold. However, antigene activity was only observed by targeting episomal viral DNA or transfected plasmids, but not the chromosome in the cell cultures. In conclusion, assembly on oligonucleotide scaffolds significantly enhanced the antisense-antigene activity of PNAs by promoting endocytosis and endosomal escape. This oligonucleotide scaffold provided a simple strategy for assembly of multiple functional peptide-PNA conjugates, expanding the applications of PNAs and demonstrating the potential of PNAs as antiviral therapeutics.
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Affiliation(s)
- Xing-Liang Zhao
- Peking University People's Hospital, Peking University Hepatology Institute, Beijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Diseases; Beijing 100044, P.R. China
| | - Bi-Cheng Chen
- Zhejiang Provincial Top Key Discipline in Surgery, Wenzhou Key Laboratory of Surgery; Department of Surgery, The First Affiliated Hospital, Wenzhou Medical University, Wenzhou, 325200, P.R. China
| | - Jin-Chao Han
- Peking University People's Hospital, Peking University Hepatology Institute, Beijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Diseases; Beijing 100044, P.R. China
| | - Lai Wei
- Peking University People's Hospital, Peking University Hepatology Institute, Beijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Diseases; Beijing 100044, P.R. China
| | - Xiao-Ben Pan
- Peking University People's Hospital, Peking University Hepatology Institute, Beijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Diseases; Beijing 100044, P.R. China
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21
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Guenther DC, Anderson GH, Karmakar S, Anderson BA, Didion BA, Guo W, Verstegen JP, Hrdlicka PJ. Invader probes: Harnessing the energy of intercalation to facilitate recognition of chromosomal DNA for diagnostic applications. Chem Sci 2015; 6:5006-5015. [PMID: 26240741 PMCID: PMC4521421 DOI: 10.1039/c5sc01238d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 06/10/2015] [Indexed: 01/01/2023] Open
Abstract
Development of probes capable of recognizing specific regions of chromosomal DNA has been a long-standing goal for chemical biologists. Current strategies such as PNA, triplex-forming oligonucleotides, and polyamides are subject to target choice limitations and/or necessitate non-physiological conditions, leaving a need for alternative approaches. Toward this end, we have recently introduced double-stranded oligonucleotide probes that are energetically activated for DNA recognition through modification with +1 interstrand zippers of intercalator-functionalized nucleotide monomers. Here, probes with different chemistries and architectures - varying in the position, number, and distance between the intercalator zippers - are studied with respect to hybridization energetics and DNA-targeting properties. Experiments with model DNA targets demonstrate that optimized probes enable efficient (C50 < 1 μM), fast (t50 < 3h), kinetically stable (> 24h), and single nucleotide specific recognition of DNA targets at physiologically relevant ionic strengths. Optimized probes were used in non-denaturing fluorescence in situ hybridization experiments for detection of gender-specific mixed-sequence chromosomal DNA target regions. These probes present themselves as a promising strategy for recognition of chromosomal DNA, which will enable development of new tools for applications in molecular biology, genomic engineering and nanotechnology.
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Affiliation(s)
- Dale C. Guenther
- Department of Chemistry , University of Idaho , 875 Perimeter Dr , Moscow , ID 83844-2343 , USA .
| | - Grace H. Anderson
- Department of Chemistry , University of Idaho , 875 Perimeter Dr , Moscow , ID 83844-2343 , USA .
- Department of Biological Sciences , Montana Tech of the University of Montana , 1300 W Park St , Butte , MT 59701-8997 , USA
| | - Saswata Karmakar
- Department of Chemistry , University of Idaho , 875 Perimeter Dr , Moscow , ID 83844-2343 , USA .
| | - Brooke A. Anderson
- Department of Chemistry , University of Idaho , 875 Perimeter Dr , Moscow , ID 83844-2343 , USA .
| | | | - Wei Guo
- MoFA , PO Box 930187, 419 Venture Ct. , Verona , WI 53593 , USA
| | | | - Patrick J. Hrdlicka
- Department of Chemistry , University of Idaho , 875 Perimeter Dr , Moscow , ID 83844-2343 , USA .
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22
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Anderson BA, Onley JJ, Hrdlicka PJ. Recognition of Double-Stranded DNA Using Energetically Activated Duplexes Modified with N2'-Pyrene-, Perylene-, or Coronene-Functionalized 2'-N-Methyl-2'-amino-DNA Monomers. J Org Chem 2015; 80:5395-406. [PMID: 25984765 DOI: 10.1021/acs.joc.5b00742] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Invader probes have been proposed as alternatives to polyamides, triplex-forming oligonucleotides, and peptide nucleic acids for recognition of chromosomal DNA targets. These double-stranded probes are activated for DNA recognition by +1 interstrand zippers of pyrene-functionalized nucleotides. This particular motif forces the intercalating pyrene moieties into the same region, resulting in perturbation and destabilization of the probe duplex. In contrast, the two probe strands display very high affinity toward complementary DNA. The energy difference between the probe duplexes and recognition complexes provides the driving force for DNA recognition. In the present study, we explore the properties of Invader probes based on larger intercalators, i.e., perylene and coronene, expecting that the larger π-surface area will result in additional destabilization of the probe duplex and further stabilization of probe-target duplexes, in effect increasing the thermodynamic driving force for DNA recognition. Toward this end, we developed protocols for 2'-N-methyl-2'-amino-2'-deoxyuridine phosphoramidites that are functionalized at the N2'-position with pyrene, perylene, or coronene moieties and incorporated these monomers into oligodeoxyribonucleotides (ONs). The resulting ONs and Invader probes are characterized by thermal denaturation experiments, analysis of thermodynamic parameters, absorption and fluorescence spectroscopy, and DNA recognition experiments. Invader probes based on large intercalators efficiently recognize model targets.
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Affiliation(s)
- Brooke A Anderson
- †Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
| | - Jared J Onley
- †Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States.,‡Department of Chemistry, Whitworth University, Spokane, Washington 99251, United States
| | - Patrick J Hrdlicka
- †Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
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23
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Alagpulinsa DA, Yaccoby S, Ayyadevara S, Shmookler Reis RJ. A peptide nucleic acid targeting nuclear RAD51 sensitizes multiple myeloma cells to melphalan treatment. Cancer Biol Ther 2015; 16:976-86. [PMID: 25996477 DOI: 10.1080/15384047.2015.1040951] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
RAD51-mediated recombinational repair is elevated in multiple myeloma (MM) and predicts poor prognosis. RAD51 has been targeted to selectively sensitize and/or kill tumor cells. Here, we employed a peptide nucleic acid (PNA) to inhibit RAD51 expression in MM cells. We constructed a PNA complementary to a unique segment of the RAD51 gene promoter, spanning the transcription start site, and conjugated it to a nuclear localization signal (PKKKRKV) to enhance cellular uptake and nuclear delivery without transfection reagents. This synthetic construct, (PNArad51_nls), significantly reduced RAD51 transcripts in MM cells, and markedly reduced the number and intensity of de novo and melphalan-induced nuclear RAD51 foci, while increasing the level of melphalan-induced γH2AX foci. Melphalan alone markedly induced the expression of 5 other genes involved in homologous-recombination repair, yet suppression of RAD51 by PNArad51_nls was sufficient to synergize with melphalan, producing significant synthetic lethality of MM cells in vitro. In a SCID-rab mouse model mimicking the MM bone marrow microenvironment, treatment with PNArad51_nls ± melphalan significantly suppressed tumor growth after 2 weeks, whereas melphalan plus control PNArad4µ_nls was ineffectual. This study highlights the importance of RAD51 in myeloma growth and is the first to demonstrate that anti-RAD51 PNA can potentiate conventional MM chemotherapy.
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24
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Brown ZZ, Müller MM, Kong HE, Lewis PW, Muir TW. Targeted Histone Peptides: Insights into the Spatial Regulation of the Methyltransferase PRC2 by using a Surrogate of Heterotypic Chromatin. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201500085] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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25
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Brown ZZ, Müller MM, Kong HE, Lewis PW, Muir TW. Targeted Histone Peptides: Insights into the Spatial Regulation of the Methyltransferase PRC2 by using a Surrogate of Heterotypic Chromatin. Angew Chem Int Ed Engl 2015; 54:6457-61. [PMID: 25873363 DOI: 10.1002/anie.201500085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 03/10/2015] [Indexed: 11/10/2022]
Abstract
Eukaryotic genomes are dynamically regulated through a host of epigenetic stimuli. The substrate for these epigenetic transactions, chromatin, is a polymer of nucleosome building blocks. In native chromatin, each nucleosome can differ from its neighbors as a result of covalent modifications to both the DNA and the histone packaging proteins. The heterotypic nature of chromatin presents a formidable obstacle to biochemical studies seeking to understand the role of context on epigenetic regulation. A chemical approach to the production of heterotypic chromatin that can be used in such studies is introduced. This method involves the attachment of a user-defined modified histone peptide to a designated nucleosome within the polymer by using a peptide nucleic acid (PNA) targeting compound. This strategy was applied to dissect the effect of chromatin context on the activity of the histone methyltransferase PRC2. The results show that PRC2 can be stimulated to produce histone H3 methylation from a defined nucleation site.
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Affiliation(s)
- Zachary Z Brown
- Department of Chemistry, Princeton University, Princeton, NJ 08544 (USA)
| | - Manuel M Müller
- Department of Chemistry, Princeton University, Princeton, NJ 08544 (USA)
| | - Ha Eun Kong
- Department of Chemistry, Princeton University, Princeton, NJ 08544 (USA).,Present address: School of Medicine, Emory University, Atlanta, GA 30322 (USA)
| | - Peter W Lewis
- Wisconsin Institute for Discovery, University of Wisconsin, Madison, WI 53715 (USA)
| | - Tom W Muir
- Department of Chemistry, Princeton University, Princeton, NJ 08544 (USA).
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26
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Shen W, Liang XH, Sun H, Crooke ST. 2'-Fluoro-modified phosphorothioate oligonucleotide can cause rapid degradation of P54nrb and PSF. Nucleic Acids Res 2015; 43:4569-78. [PMID: 25855809 PMCID: PMC4482069 DOI: 10.1093/nar/gkv298] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/26/2015] [Indexed: 12/14/2022] Open
Abstract
Synthetic oligonucleotides are used to regulate gene expression through different mechanisms. Chemical modifications of the backbone of the nucleic acid and/or of the 2′ moiety of the ribose can increase nuclease stability and/or binding affinity of oligonucleotides to target molecules. Here we report that transfection of 2′-F-modified phosphorothioate oligonucleotides into cells can reduce the levels of P54nrb and PSF proteins through proteasome-mediated degradation. Such deleterious effects of 2′-F-modified oligonucleotides were observed in different cell types from different species, and were independent of oligonucleotide sequence, positions of the 2′-F-modified nucleotides in the oligonucleotides, method of delivery or mechanism of action of the oligonucleotides. Four 2′-F-modified nucleotides were sufficient to cause the protein reduction. P54nrb and PSF belong to Drosophila behavior/human splicing (DBHS) family. The third member of the family, PSPC1, was also reduced by the 2′-F-modified oligonucleotides. Preferential association of 2′-F-modified oligonucleotides with P54nrb was observed, which is partially responsible for the protein reduction. Consistent with the role of DBHS proteins in double-strand DNA break (DSB) repair, elevated DSBs were observed in cells treated with 2′-F-modified oligonucleotides, which contributed to severe impairment in cell proliferation. These results suggest that oligonucleotides with 2′-F modifications can cause non-specific loss of cellular protein(s).
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Affiliation(s)
- Wen Shen
- Department of Core Antisense Research, ISIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Xue-Hai Liang
- Department of Core Antisense Research, ISIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Hong Sun
- Department of Core Antisense Research, ISIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Stanley T Crooke
- Department of Core Antisense Research, ISIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA 92010, USA
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27
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Karmakar S, Madsen AS, Guenther DC, Gibbons BC, Hrdlicka PJ. Recognition of double-stranded DNA using energetically activated duplexes with interstrand zippers of 1-, 2- or 4-pyrenyl-functionalized O2'-alkylated RNA monomers. Org Biomol Chem 2014; 12:7758-73. [PMID: 25144705 PMCID: PMC4167914 DOI: 10.1039/c4ob01183j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Despite advances with triplex-forming oligonucleotides, peptide nucleic acids, polyamides and--more recently--engineered proteins, there remains an urgent need for synthetic ligands that enable specific recognition of double-stranded (ds) DNA to accelerate studies aiming at detecting, regulating and modifying genes. Invaders, i.e., energetically activated DNA duplexes with interstrand zipper arrangements of intercalator-functionalized nucleotides, are emerging as an attractive approach toward this goal. Here, we characterize and compare Invaders based on 1-, 2- and 4-pyrenyl-functionalized O2'-alkylated uridine monomers X-Z by means of thermal denaturation experiments, optical spectroscopy, force-field simulations and recognition experiments using DNA hairpins as model targets. We demonstrate that Invaders with +1 interstrand zippers of X or Y monomers efficiently recognize mixed-sequence DNA hairpins with single nucleotide fidelity. Intercalator-mediated unwinding and activation of the double-stranded probe, coupled with extraordinary stabilization of probe-target duplexes (ΔT(m)/modification up to +14.0 °C), provides the driving force for dsDNA recognition. In contrast, Z-modified Invaders show much lower dsDNA recognition efficiency. Thus, even very conservative changes in the chemical makeup of the intercalator-functionalized nucleotides used to activate Invader duplexes, affects dsDNA-recognition efficiency of the probes, which highlights the importance of systematic structure-property studies. The insight from this study will guide future design of Invaders for applications in molecular biology and nucleic acid diagnostics.
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Affiliation(s)
- Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID 83844, USA.
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28
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Karmakar S, Guenther DC, Hrdlicka PJ. Recognition of mixed-sequence DNA duplexes: design guidelines for invaders based on 2'-O-(pyren-1-yl)methyl-RNA monomers. J Org Chem 2013; 78:12040-8. [PMID: 24195730 PMCID: PMC3903098 DOI: 10.1021/jo402085v] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The development of agents that recognize mixed-sequence double-stranded DNA (dsDNA) is desirable because of their potential as tools for detection, regulation, and modification of genes. Despite progress with triplex-forming oligonucleotides, peptide nucleic acids, polyamides, and other approaches, recognition of mixed-sequence dsDNA targets remains challenging. Our laboratory studies Invaders as an alternative approach toward this end. These double-stranded oligonucleotide probes are activated for recognition of mixed-sequence dsDNA through modification with +1 interstrand zippers of intercalator-functionalized nucleotides such as 2'-O-(pyren-1-yl)methyl-RNA monomers and have recently been shown to recognize linear dsDNA, DNA hairpins, and chromosomal DNA. In the present work, we systematically studied the influence that the nucleobase moieties of the 2'-O-(pyren-1-yl)methyl-RNA monomers have on the recognition efficiency of Invader duplexes. Results from thermal denaturation, binding energy, and recognition experiments using Invader duplexes with different +1 interstrand zippers of the four canonical 2'-O-(pyren-1-yl)methyl-RNA A/C/G/U monomers show that incorporation of these motifs is a general strategy for activation of probes for recognition of dsDNA. Probe duplexes with interstrand zippers comprising C and/or U monomers result in the most efficient recognition of dsDNA. The insight gained from this study will drive the design of efficient Invaders for applications in molecular biology, nucleic acid diagnostics, and biotechnology.
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Affiliation(s)
- Saswata Karmakar
- Department of Chemistry, University of Idaho , 875 Perimeter Drive, MS 2343, Moscow, Idaho 83844-2343, United States
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29
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Sau SP, Madsen AS, Podbevsek P, Andersen NK, Kumar TS, Andersen S, Rathje RL, Anderson BA, Guenther DC, Karmakar S, Kumar P, Plavec J, Wengel J, Hrdlicka PJ. Identification and characterization of second-generation invader locked nucleic acids (LNAs) for mixed-sequence recognition of double-stranded DNA. J Org Chem 2013; 78:9560-70. [PMID: 24032477 PMCID: PMC3833467 DOI: 10.1021/jo4015936] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The development of synthetic agents that recognize double-stranded DNA (dsDNA) is a long-standing goal that is inspired by the promise for tools that detect, regulate, and modify genes. Progress has been made with triplex-forming oligonucleotides, peptide nucleic acids, and polyamides, but substantial efforts are currently devoted to the development of alternative strategies that overcome the limitations observed with the classic approaches. In 2005, we introduced Invader locked nucleic acids (LNAs), i.e., double-stranded probes that are activated for mixed-sequence recognition of dsDNA through modification with "+1 interstrand zippers" of 2'-N-(pyren-1-yl)methyl-2'-amino-α-l-LNA monomers. Despite promising preliminary results, progress has been slow because of the synthetic complexity of the building blocks. Here we describe a study that led to the identification of two simpler classes of Invader monomers. We compare the thermal denaturation characteristics of double-stranded probes featuring different interstrand zippers of pyrene-functionalized monomers based on 2'-amino-α-l-LNA, 2'-N-methyl-2'-amino-DNA, and RNA scaffolds. Insights from fluorescence spectroscopy, molecular modeling, and NMR spectroscopy are used to elucidate the structural factors that govern probe activation. We demonstrate that probes with +1 zippers of 2'-O-(pyren-1-yl)methyl-RNA or 2'-N-methyl-2'-N-(pyren-1-yl)methyl-2'-amino-DNA monomers recognize DNA hairpins with similar efficiency as original Invader LNAs. Access to synthetically simple monomers will accelerate the use of Invader-mediated dsDNA recognition for applications in molecular biology and nucleic acid diagnostics.
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Affiliation(s)
- Sujay P. Sau
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA
| | - Andreas S. Madsen
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
| | | | - Nicolai K. Andersen
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
| | - T. Santhosh Kumar
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
| | - Sanne Andersen
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
| | - Rie L. Rathje
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
| | | | - Dale C. Guenther
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA
| | - Saswata Karmakar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA
| | - Pawan Kumar
- Department of Chemistry, University of Idaho, Moscow, ID-83844, USA
| | - Janez Plavec
- National Institute of Chemistry, Ljubljana, Slovenia
| | - Jesper Wengel
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, Odense, Denmark
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30
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Yaroslavsky AI, Smolina IV. Fluorescence imaging of single-copy DNA sequences within the human genome using PNA-directed padlock probe assembly. ACTA ACUST UNITED AC 2013; 20:445-53. [PMID: 23521801 DOI: 10.1016/j.chembiol.2013.02.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/24/2012] [Accepted: 02/07/2013] [Indexed: 01/07/2023]
Abstract
We present an approach for fluorescent in situ detection of short, single-copy sequences within genomic DNA in human cells. The single-copy sensitivity and single-base specificity of our method is achieved due to the combination of three components. First, a peptide nucleic acid (PNA) probe locally opens a chosen target site, which allows a padlock DNA probe to access the site and become ligated. Second, rolling circle amplification (RCA) generates thousands of single-stranded copies of the target sequence. Finally, fluorescent in situ hybridization (FISH) is used to visualize the amplified DNA. We validate this technique by successfully detecting six single-copy target sites on human mitochondrial and autosomal DNA. We also demonstrate the high selectivity of this method by detecting X- and Y-specific sequences on human sex chromosomes and by simultaneously detecting three sequence-specific target sites. Finally, we discriminate two target sites that differ by 2 nt. The PNA-RCA-FISH approach is a distinctive in situ hybridization method capable of multitarget visualization within human chromosomes and nuclei that does not require DNA denaturation and is extremely sequence specific.
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31
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Didion BA, Karmakar S, Guenther DC, Sau SP, Verstegen JP, Hrdlicka PJ. Invaders: Recognition of Double-Stranded DNA by Using Duplexes Modified with Interstrand Zippers of 2'-O-(Pyren-1-yl)methyl-ribonucleotides. Chembiochem 2013; 14:1534-1538. [PMID: 24038876 PMCID: PMC3838861 DOI: 10.1002/cbic.201300414] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Indexed: 12/23/2022]
Abstract
The invasion has begun: Invaders are shown to recognize DNA hairpins in cell-free assays and chromosomal DNA during non-denaturing fluorescence in situ hybridization (nd-FISH) experiments. As Invaders are devoid of inherent sequence limitations, many previously inaccessible DNA targets could become accessible to exogenous control with important ramifications for karyotyping, in vivo imaging, and gene regulation.
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Affiliation(s)
- Bradley A Didion
- Minitube of America, Inc. PO Box 930187, 419 Venture Ct., Verona, WI 53593 (USA)
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32
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Badı́a C, Souard F, Vicent C. Sugar–Oligoamides: Synthesis of DNA Minor Groove Binders. J Org Chem 2012; 77:10870-81. [DOI: 10.1021/jo302238u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Concepción Badı́a
- Departamento de Sı́ntesis,
Estructura y Propiedades de los Compuestos Orgánicos, Instituto de Quı́mica Orgánica General,
CSIC, c/Juan de la Cierva 3, 28006 Madrid, Spain
| | - Florence Souard
- Departamento de Sı́ntesis,
Estructura y Propiedades de los Compuestos Orgánicos, Instituto de Quı́mica Orgánica General,
CSIC, c/Juan de la Cierva 3, 28006 Madrid, Spain
| | - Cristina Vicent
- Departamento de Sı́ntesis,
Estructura y Propiedades de los Compuestos Orgánicos, Instituto de Quı́mica Orgánica General,
CSIC, c/Juan de la Cierva 3, 28006 Madrid, Spain
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33
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Efthymiou T, Gong W, Desaulniers JP. Chemical architecture and applications of nucleic acid derivatives containing 1,2,3-triazole functionalities synthesized via click chemistry. Molecules 2012; 17:12665-703. [PMID: 23103533 PMCID: PMC6268694 DOI: 10.3390/molecules171112665] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/19/2012] [Accepted: 10/19/2012] [Indexed: 11/16/2022] Open
Abstract
There is considerable attention directed at chemically modifying nucleic acids with robust functional groups in order to alter their properties. Since the breakthrough of copper-assisted azide-alkyne cycloadditions (CuAAC), there have been several reports describing the synthesis and properties of novel triazole-modified nucleic acid derivatives for potential downstream DNA- and RNA-based applications. This review will focus on highlighting representative novel nucleic acid molecular structures that have been synthesized via the “click” azide-alkyne cycloaddition. Many of these derivatives show compatibility for various applications that involve enzymatic transformation, nucleic acid hybridization, molecular tagging and purification, and gene silencing. The details of these applications are discussed. In conclusion, the future of nucleic acid analogues functionalized with triazoles is promising.
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Affiliation(s)
| | | | - Jean-Paul Desaulniers
- Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe St N, Oshawa, ON L1H 7K4, Canada
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34
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Kim JE, Yoon S, Mok H, Jung W, Kim DE. Site-specific cleavage of mutant ABL mRNA by DNAzyme is facilitated by peptide nucleic acid binding to RNA substrate. FEBS Lett 2012; 586:3865-9. [PMID: 23010596 DOI: 10.1016/j.febslet.2012.09.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/04/2012] [Accepted: 09/08/2012] [Indexed: 01/01/2023]
Abstract
RNA-cleaving DNAzymes were constructed to target the point mutation in the BCR-ABL transcript that causes imatinib resistance in leukemic cells. We examined the effect of 12mer peptide nucleic acids (PNAs) as facilitator oligonucleotides that bind to RNA substrate at the termini of the DNAzyme to improve DNAzyme-mediated cleavage of full-length RNA. When imatinib-resistant cells were transfected with the facilitator PNA and DNAzyme, DNAzyme activity was enhanced and the cells were sensitized to imatinib treatment. Thus, facilitator PNA may be used to enhance activity of antisense oligonucleotide targeting the full-length transcript.
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MESH Headings
- Animals
- Antineoplastic Agents/pharmacology
- Base Sequence
- Benzamides
- Cell Line, Tumor
- DNA, Catalytic/chemical synthesis
- DNA, Catalytic/genetics
- DNA, Catalytic/metabolism
- Genes, abl
- Genetic Engineering
- Humans
- Imatinib Mesylate
- Mice
- Molecular Sequence Data
- Nucleic Acid Conformation
- Oligonucleotides, Antisense/genetics
- Peptide Nucleic Acids/chemistry
- Peptide Nucleic Acids/genetics
- Peptide Nucleic Acids/metabolism
- Piperazines/pharmacology
- Polymorphism, Single Nucleotide
- Pyrimidines/pharmacology
- RNA Cleavage/drug effects
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Substrate Specificity
- Transfection
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Affiliation(s)
- Ji Eun Kim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea
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35
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Peñalver P, Marcelo F, Jiménez-Barbero J, Vicent C. Carbohydrate recognition at the minor-groove of the self-complementary duplex d(CGCGAATTCGCG)2 by a synthetic glyco-oligoamide. Chemistry 2011; 17:4561-70. [PMID: 21259350 DOI: 10.1002/chem.201003027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Indexed: 12/20/2022]
Abstract
The structure of a neutral glyco-conjugate β-Gal-Py-γ-Py-Ind (1), designed as a probe for analyzing sugar-DNA interactions, when bound to a self-complementary oligonucleotide duplex d(CGCG AATT CGCG)(2) has been deduced by employing (1)H NMR techniques. Analysis of the formed 1:1 complex demonstrated that the glycol ligand is bound in a hairpin-like conformation in which both pyrrole amino acid moieties are stacked, whereas the indole and the sugar residues are spatially close. The binding site is defined by the minor groove formed by the -AATT- stretch. In particular, the -Py-γ-Py- region of the ligand is sited near the A5-A6 oligonucleotide residues, whereas the indole and the sugar rings are next to the T7-T8 base pairs. More relevant, the existence of a variety of intermolecular NOE correlations permitted the close proximity of the sugar to the minor groove to be assessed, thus showing that the binding of the glycoconjugate at the minor groove is the origin of the specificity of the glycoconjugate-DNA interaction. The experimental NMR data have been combined with restrained and unrestrained molecular dynamics calculations, to provide the 3D structure of the complex.
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Affiliation(s)
- Pablo Peñalver
- Departamento de Síntesis, Estructura y Propiedades de Compuestos Orgánicos (SEPCO), Instituto de Química Orgánica general CSIC, c/Juan de la Cierva 3, 28006, Madrid, Spain
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36
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Design of embedded chimeric peptide nucleic acids that efficiently enter and accurately reactivate gene expression in vivo. Proc Natl Acad Sci U S A 2010; 107:16846-51. [PMID: 20837550 DOI: 10.1073/pnas.0912896107] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pharmacological treatments designed to reactivate fetal γ-globin can lead to an effective and successful clinical outcome in patients with hemoglobinopathies. However, new approaches remain highly desired because such treatments are not equally effective for all patients, and toxicity issues remain. We have taken a systematic approach to develop an embedded chimeric peptide nucleic acid (PNA) that effectively enters the cell and the nucleus, binds to its target site at the human fetal γ-globin promoter, and reactivates this transcript in adult transgenic mouse bone marrow and human primary peripheral blood cells. In vitro and in vivo DNA-binding assays in conjunction with live-cell imaging have been used to establish and optimize chimeric PNA design parameters that lead to successful gene activation. Our final molecule contains a specific γ-promoter-binding PNA sequence embedded within two amino acid motifs: one leads to efficient cell/nuclear entry, and the other generates transcriptional reactivation of the target. These embedded PNAs overcome previous limitations and are generally applicable to the design of in vivo transcriptional activation reagents that can be directed to any promoter region of interest and are of direct relevance to clinical applications that would benefit from such a need.
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37
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Mulders SAM, van Engelen BGM, Wieringa B, Wansink DG. Molecular therapy in myotonic dystrophy: focus on RNA gain-of-function. Hum Mol Genet 2010; 19:R90-7. [DOI: 10.1093/hmg/ddq161] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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38
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Tavares MA, Yi S, Masangcay CY, Ota MM, Herrmann PC. Chromogenic In Situ Hybridization Using Peptide Nucleic Acid Probes: A Promising Adjunct to Immunohistochemistry for Identifying Light Chain Restriction in Multiple Myeloma Patients. Lab Med 2010. [DOI: 10.1309/lmq2lz7sscaj6jqi] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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39
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Sau SP, Kumar TS, Hrdlicka PJ. Invader LNA: efficient targeting of short double stranded DNA. Org Biomol Chem 2010; 8:2028-36. [PMID: 20401378 DOI: 10.1039/b923465a] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Despite progress with triplex-forming oligonucleotides or helix-invading peptide nucleic acids (PNAs), there remains a need for probes facilitating sequence-unrestricted targeting of double stranded DNA (dsDNA) at physiologically relevant conditions. Invader LNA probes, i.e., DNA duplexes with "+1 interstrand zipper arrangements" of intercalator-functionalized 2'-amino-alpha-l-LNA monomers, are demonstrated herein to recognize short mixed sequence dsDNA targets. This approach, like pseudo-complementary PNA (pcPNA), relies on relative differences in stability between probe duplexes and the corresponding probe:target duplexes for generation of a favourable thermodynamic gradient. Unlike pcPNA, Invader LNA probes take advantage of the "nearest neighbour exclusion principle", i.e., intercalating units of Invader LNA monomers are poorly accommodated in probe duplexes but extraordinarily well tolerated in probe-target duplexes (DeltaT(m)/modification up to +11.5 degrees C). Recognition of isosequential dsDNA-targets occurs: a) at experimental temperatures much lower than the thermal denaturation temperatures (T(m)'s) of Invader LNAs or dsDNA-targets, b) at a wide range of ionic strengths, and c) with good mismatch discrimination. Recognition of dsDNA is monitored in real-time using inherent pyrene-pyrene excimer signals of Invader LNA probes, which provides insights into reaction kinetics and enables rational design of probes. These properties render Invader LNAs as promising probes for biomedical applications entailing sequence-unrestricted recognition of dsDNA.
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Affiliation(s)
- Sujay P Sau
- Department of Chemistry, University of Idaho, Moscow, ID 83844-2343, USA
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40
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Lu XW, Zeng Y, Liu CF. Modulating the hybridization property of PNA with a peptoid-like side chain. Org Lett 2009; 11:2329-32. [PMID: 19438197 DOI: 10.1021/ol900587b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modification on the gamma-N of the PNA backbone yielded a PNA analogue with a peptoid-like side chain. We found that the length of the side chain was important in influencing the hybridization affinity of the modified PNA.
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Affiliation(s)
- Xiao-Wei Lu
- Division of Chemical Biology and Biotechnology, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
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41
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Hansen ME, Bentin T, Nielsen PE. High-affinity triplex targeting of double stranded DNA using chemically modified peptide nucleic acid oligomers. Nucleic Acids Res 2009; 37:4498-507. [PMID: 19474349 PMCID: PMC2715256 DOI: 10.1093/nar/gkp437] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
While sequence-selective dsDNA targeting by triplex forming oligonucleotides has been studied extensively, only very little is known about the properties of PNA–dsDNA triplexes—mainly due to the competing invasion process. Here we show that when appropriately modified using pseudoisocytosine substitution, in combination with (oligo)lysine or 9-aminoacridine conjugation, homopyrimidine PNA oligomers bind complementary dsDNA targets via triplex formation with (sub)nanomolar affinities (at pH 7.2, 150 mM Na+). Binding affinity can be modulated more than 1000-fold by changes in pH, PNA oligomer length, PNA net charge and/or by substitution of pseudoisocytosine for cytosine, and conjugation of the DNA intercalator 9-aminoacridine. Furthermore, 9-aminoacridine conjugation also strongly enhanced triplex invasion. Specificity for the fully matched target versus one containing single centrally located mismatches was more than 150-fold. Together the data support the use of homopyrimidine PNAs as efficient and sequence selective tools in triplex targeting strategies under physiological relevant conditions.
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Affiliation(s)
- Mads E Hansen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen 2200-N, Denmark
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42
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Beane R, Gabillet S, Montaillier C, Arar K, Corey DR. Recognition of chromosomal DNA inside cells by locked nucleic acids. Biochemistry 2009; 47:13147-9. [PMID: 19053275 DOI: 10.1021/bi801930p] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sequence-selective recognition of DNA inside cells by oligonucleotides would provide valuable insights into cellular processes and new leads for therapeutics. Recent work, however, has shown that noncoding RNA transcripts overlap chromosomal DNA. These RNAs provide alternate targets for oligonucleotides designed to bind promoter DNA, potentially overturning previous assumptions about mechanism. Here, we show that antigene locked nucleic acids (agLNAs) reduce RNA levels of targeted genes, block RNA polymerase and transcription factor association at gene promoters, and bind to chromosomal DNA. These data suggest that the mechanism of LNAs involves recognition of chromosomal DNA and that LNAs are bona fide antigene molecules.
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Affiliation(s)
- Randall Beane
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Road, Dallas, Texas 75390-9041, USA
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43
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Brown EMB, Paunesku T, Wu A, Thurn KT, Haley B, Clark J, Priester T, Woloschak GE. Methods for assessing DNA hybridization of peptide nucleic acid-titanium dioxide nanoconjugates. Anal Biochem 2008; 383:226-35. [PMID: 18786502 DOI: 10.1016/j.ab.2008.08.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 07/28/2008] [Accepted: 08/09/2008] [Indexed: 12/25/2022]
Abstract
We describe the synthesis of peptide nucleic acid (PNA)-titanium dioxide (TiO(2)) nanoconjugates and several novel methods developed to investigate the DNA hybridization behaviors of these constructs. PNAs are synthetic DNA analogs resistant to degradation by cellular enzymes that hybridize to single-stranded DNA (ssDNA) with higher affinity than DNA oligonucleotides, invade double-stranded DNA (dsDNA), and form different PNA/DNA complexes. Previously, we developed a DNA-TiO(2) nanoconjugate capable of hybridizing to target DNA intracellularly in a sequence-specific manner with the ability to cleave DNA when excited by electromagnetic radiation but susceptible to degradation that may lower its intracellular targeting efficiency and retention time. PNA-TiO(2) nanoconjugates described in the current article hybridize to target ssDNA, oligonucleotide dsDNA, and supercoiled plasmid DNA under physiological-like ionic and temperature conditions, enabling rapid, inexpensive, sequence-specific concentration of nucleic acids in vitro. When modified by the addition of imaging agents or peptides, hybridization capabilities of PNA-TiO(2) nanoconjugates are enhanced, providing essential benefits for numerous in vitro and in vivo applications. The series of experiments shown here could not be done with either TiO(2)-DNA nanoconjugates or PNAs alone, and the novel methods developed will benefit studies of numerous other nanoconjugate systems.
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Affiliation(s)
- Eric M B Brown
- Department of Radiation Oncology, Northwestern University, Feinberg School of Medicine, 303 E. Chicago Avenue, Ward-13-002, Chicago, IL 60611, USA
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44
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Faccini A, Tortori A, Tedeschi T, Sforza S, Tonelli R, Pession A, Corradini R, Marchelli R. Circular dichroism study of DNA binding by a potential anticancer peptide nucleic acid targeted against the MYCN oncogene. Chirality 2008; 20:494-500. [PMID: 17963203 DOI: 10.1002/chir.20489] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The interaction with DNA of a peptide nucleic acid (PNA) oligomer (16nt) conjugated with a nuclear localization signal (NLS) peptide, which was previously found to be able to inhibit tumor cell proliferation through block of transcription of the MYCN oncogene, was studied by UV and CD spectroscopy. While data obtained by UV were not conclusive, the use of circular dichroism gave clear-cut evidence of the formation of a PNA:DNA duplex of exceptionally high stability (Tm >or= 90 degrees C). Using the same approach, the effect of mutations on DNA:PNA stability was evaluated, and was found in accordance with that expected for a Watson-Crick interaction. The role of the NLS peptide was evaluated by using a PNA lacking of this part, which gave rise to less stable PNA:DNA duplexes. Finally, a competition experiment carried out with a 26mer dsDNA, containing the target 16mer sequence in its middle region, in the presence of PNA-NLS gave evidence for the formation of a ternary complex at 25 degrees , while at higher temperature, the PNA:DNA duplex and the displaced homologous DNA strand were detected. The present results support the possibility of an analogous mechanism of action of this antitumor PNA in vivo.
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Affiliation(s)
- Andrea Faccini
- Dipartimento di Chimica, Organica e Industriale, Università di Parma, Parma, Italy
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45
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Fabani MM, Ivanova GD, Gait MJ. Peptide–Peptide Nucleic Acid Conjugates for Modulation of Gene Expression. THERAPEUTIC OLIGONUCLEOTIDES 2008. [DOI: 10.1039/9781847558275-00080] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Martin M. Fabani
- Medical Research Council Laboratory of Molecular Biology Hills Road Cambridge CB2 0QH UK
| | - Gabriela D. Ivanova
- Medical Research Council Laboratory of Molecular Biology Hills Road Cambridge CB2 0QH UK
| | - Michael J. Gait
- Medical Research Council Laboratory of Molecular Biology Hills Road Cambridge CB2 0QH UK
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46
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Ishizuka T, Yoshida J, Yamamoto Y, Sumaoka J, Tedeschi T, Corradini R, Sforza S, Komiyama M. Chiral introduction of positive charges to PNA for double-duplex invasion to versatile sequences. Nucleic Acids Res 2008; 36:1464-71. [PMID: 18203747 PMCID: PMC2275137 DOI: 10.1093/nar/gkm1154] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 12/12/2007] [Accepted: 12/12/2007] [Indexed: 11/12/2022] Open
Abstract
Invasion of two PNA strands to double-stranded DNA is one of the most promising methods to recognize a predetermined site in double-stranded DNA (PNA = peptide nucleic acid). In order to facilitate this 'double-duplex invasion', a new type of PNA was prepared by using chiral PNA monomers in which a nucleobase was bound to the alpha-nitrogen of N-(2-aminoethyl)-d-lysine. These positively charged monomer units, introduced to defined positions in Nielsen's PNAs (poly[N-(2-aminoethyl)glycine] derivatives), promoted the invasion without impairing mismatch-recognizing activity. When pseudo-complementary nucleobases 2,6-diaminopurine and 2-thiouracil were bound to N-(2-aminoethyl)-d-lysine, the invasion successfully occurred even at highly G-C-rich regions [e.g. (G/C)7(A/T)3 and (G/C)8(A/T)2] which were otherwise hardly targeted. Thus, the scope of sequences available as the target site has been greatly expanded. In contrast with the promotion by the chiral PNA monomers derived from N-(2-aminoethyl)-d-lysine, their l-isomers hardly invaded, showing crucial importance of the d-chirality. The promotion of double-duplex invasion by the chiral (d) PNA monomer units was ascribed to both destabilization of PNA/PNA duplex and stabilization of PNA/DNA duplexes.
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Affiliation(s)
- Takumi Ishizuka
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Junya Yoshida
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Yoji Yamamoto
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Jun Sumaoka
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Tullia Tedeschi
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Roberto Corradini
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Stefano Sforza
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
| | - Makoto Komiyama
- Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan and Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, Parma, I-43100 Italy
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47
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Doria F, Richter SN, Nadai M, Colloredo-Mels S, Mella M, Palumbo M, Freccero M. BINOL-amino acid conjugates as triggerable carriers of DNA-targeted potent photocytotoxic agents. J Med Chem 2007; 50:6570-9. [PMID: 18047263 DOI: 10.1021/jm070828x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mild photoactivation of new BINOL-amino acid and -amino ester conjugates (BINOLAMs) yielded alkylating and DNA cross-linking agents with high photoefficiency and superior cytotoxicity. Detection of the transient electrophile, by laser flash photolysis (LFP), suggests that BINOL-quinone methides (QMs) are key intermediates in the process. QMs trapping by water, monitored in a time-dependent product distribution analysis, demonstrated that the phototriggered reactivity of BINOLAMs as bis-alkylating agents is the result of a two-step process involving sequential photogeneration of monoalkylating QMs. Light activation of the BINOL-L-amino esters produced cytotoxic QMs very effective against human tumor LoVo cells with EC50 in the 130-230 nM range. Trimethylpsoralen (PS) is about 4 times less potent than our newly tested compounds. BINOL-L-proline methyl ester showed notable photoselectivity because it displayed cytotoxic effects upon irradiation only and was able to efficiently reach the target DNA inside the cells, where it forms both alkylated and cross-linked species.
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Affiliation(s)
- Filippo Doria
- Dipartimento di Chimica Organica, Università di Pavia, Italy
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48
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Xiao M, Gordon MP, Phong A, Ha C, Chan TF, Cai D, Selvin PR, Kwok PY. Determination of haplotypes from single DNA molecules: a method for single-molecule barcoding. Hum Mutat 2007; 28:913-21. [PMID: 17443670 DOI: 10.1002/humu.20528] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Determining the haplotypes in a diploid individual is a major technical challenge in genetic studies of human complex traits. Here we report a method of molecular haplotyping by directly imaging multiple polymorphic sites on individual DNA molecules simultaneously. DNA fragments amplified by long-range PCR were labeled with fluorescent dyes at each polymorphic site using a modified gap-filled padlock probe ligation approach. The labeled DNA molecules were then stretched into linear form on a functionalized glass surface and imaged with multicolor total internal reflection fluorescence (TIRF) microscopy. By determining the colors and positions of the fluorescent labels with respect to the backbone at polymorphic sites, the haplotype can be inferred accurately, in a manner similar to reading a barcode, even when the DNA fragments are not fully labeled. The feasibility of this technology is demonstrated by the determination of the haplotype of a 9.3-kbp DNA fragment containing four SNPs.
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Affiliation(s)
- Ming Xiao
- Cardiovascular Research Institute and Center for Human Genetics, University of California, San Francisco, San Francisco, California
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49
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Beane RL, Ram R, Gabillet S, Arar K, Monia BP, Corey DR. Inhibiting gene expression with locked nucleic acids (LNAs) that target chromosomal DNA. Biochemistry 2007; 46:7572-80. [PMID: 17536839 PMCID: PMC2527755 DOI: 10.1021/bi700227g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Oligonucleotides containing locked nucleic acid bases (LNAs) have increased affinity for complementary DNA sequences. We hypothesized that enhanced affinity might allow LNAs to recognize chromosomal DNA inside human cells and inhibit gene expression. To test this hypothesis, we synthesized antigene LNAs (agLNAs) complementary to sequences within the promoters of progesterone receptor (PR) and androgen receptor (AR). We observed inhibition of AR and PR expression by agLNAs but not by analogous oligomers containing 2'-methoxyethyl bases or noncomplementary LNAs. Inhibition was dose dependent and exhibited IC50 values of <10 nM. Efficient inhibition depended on the length of the agLNA, the location of LNA bases, the number of LNA substitutions, and the location of the target sequence within the targeted promoter. LNAs targeting sequences at or near transcription start sites yielded better inhibition than LNAs targeting transcription factor binding sites or an inverted repeat. These results demonstrate that agLNAs can recognize chromosomal target sequences and efficiently block gene expression. agLNAs could be used for gene silencing, as cellular probes for chromosome structure, and therapeutic applications.
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Affiliation(s)
- Randall L. Beane
- The Departments of Pharmacology and Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Road, Dallas, TX, 75390-9041
| | - Rosalyn Ram
- The Departments of Pharmacology and Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Road, Dallas, TX, 75390-9041
| | - Sylvie Gabillet
- SIGMA-Proligo Genopole Campus 1 5, rue Desbruères, 91030 Evry Cedex, France
| | - Khalil Arar
- SIGMA-Proligo Genopole Campus 1 5, rue Desbruères, 91030 Evry Cedex, France
| | | | - David R. Corey
- The Departments of Pharmacology and Biochemistry, University of Texas Southwestern Medical Center at Dallas, 6001 Forest Park Road, Dallas, TX, 75390-9041
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50
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Janowski BA, Hu J, Corey DR. Silencing gene expression by targeting chromosomal DNA with antigene peptide nucleic acids and duplex RNAs. Nat Protoc 2007; 1:436-43. [PMID: 17406266 DOI: 10.1038/nprot.2006.64] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The value of recognizing cellular RNA sequences by short interfering RNAs (siRNAs) in mammalian cells is widely appreciated, but what might be learned if it were also possible to recognize chromosomal DNA? Recognition of chromosomal DNA would have many applications, such as inhibiting gene expression, activating gene expression, introducing mutations, and probing chromosome structure and function. We have shown that antigene peptide nucleic acids (agPNAs) and antigene duplex RNAs (agRNAs) block gene expression and probe chromosomal DNA. Here we describe a protocol for designing antigene agents and introducing them into cells. This protocol can also be used to silence expression with PNAs or siRNAs that target mRNA. From preparation of oligomers to analysis of data, experiments with agPNAs and agRNAs require approximately 14 d and 9 d, respectively.
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Affiliation(s)
- Bethany A Janowski
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9041, USA.
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