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Gafur SH, Ghosh S, Richter M, Rozners E. Synthesis and Properties of RNA Modified with Thioamide Internucleoside Linkage. Chembiochem 2024; 25:e202400364. [PMID: 38819607 DOI: 10.1002/cbic.202400364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 05/23/2024] [Accepted: 05/31/2024] [Indexed: 06/01/2024]
Abstract
Recent success of RNA therapeutics has reinvigorated interest in chemical modifications of RNA. As exemplified by the phosphorothioates, modifications of sugar-phosphate backbone have been remarkably impactful but relatively underexplored in therapeutic RNAs. The present study reports synthesis, thermal stability, and RNA interference activity of RNAs modified with thioamide linkages. Compared to the previously studied amide-modified RNA, thioamide linkages strongly destabilized a short self-complementary RNA model duplex. However, in short interfering RNAs amides and thioamides had a similar effect on duplex stability and target RNA cleavage activity and specificity. Hence, the thioamide may be added to the toolbox of chemical biologist as a useful backbone modification well tolerated by the RNA interference machinery.
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Affiliation(s)
- Sayed Habibul Gafur
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - Samir Ghosh
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - Michael Richter
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, Binghamton, New York, 13902, USA
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2
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Li Q, Dong M, Chen P. Advances in structural-guided modifications of siRNA. Bioorg Med Chem 2024; 110:117825. [PMID: 38954918 DOI: 10.1016/j.bmc.2024.117825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/27/2024] [Accepted: 06/27/2024] [Indexed: 07/04/2024]
Abstract
To date, the US Food and Drug Administration (FDA) has approved six small interfering RNA (siRNA) drugs: patisiran, givosiran, lumasiran, inclisiran, vutrisiran, and nedosiran, serving as compelling evidence of the promising potential of RNA interference (RNAi) therapeutics. The successful implementation of siRNA therapeutics is improved through a combination of various chemical modifications and diverse delivery approaches. The utilization of chemically modified siRNA at specific sites on either the sense strand (SS) or antisense strand (AS) has the potential to enhance resistance to ribozyme degradation, improve stability and specificity, and prolong the efficacy of drugs. Herein, we provide comprehensive analyses concerning the correlation between chemical modifications and structure-guided siRNA design. Various modifications, such as 2'-modifications, 2',4'-dual modifications, non-canonical sugar modifications, and phosphonate mimics, are crucial for the activity of siRNA. We also emphasize the essential strategies for enhancing overhang stability, improving RISC loading efficacy and strand selection, reducing off-target effects, and discussing the future of targeted delivery.
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Affiliation(s)
- Qiang Li
- Department of Medicinal Chemistry, School of Pharmacy, Qingdao University, Qingdao 266021, China; Research and Development Department, NanoPeptide (Qingdao) Biotechnology Ltd., Qingdao, China.
| | - Mingxin Dong
- Department of Medicinal Chemistry, School of Pharmacy, Qingdao University, Qingdao 266021, China.
| | - Pu Chen
- Research and Development Department, NanoPeptide (Qingdao) Biotechnology Ltd., Qingdao, China; Department of Chemical Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON, Canada.
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3
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Yamada K, Hariharan VN, Caiazzi J, Miller R, Ferguson CM, Sapp E, Fakih HH, Tang Q, Yamada N, Furgal RC, Paquette JD, Biscans A, Bramato BM, McHugh N, Summers A, Lochmann C, Godinho BMDC, Hildebrand S, Jackson SO, Echeverria D, Hassler MR, Alterman JF, DiFiglia M, Aronin N, Khvorova A. Enhancing siRNA efficacy in vivo with extended nucleic acid backbones. Nat Biotechnol 2024:10.1038/s41587-024-02336-7. [PMID: 39090305 DOI: 10.1038/s41587-024-02336-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 06/25/2024] [Indexed: 08/04/2024]
Abstract
Therapeutic small interfering RNA (siRNA) requires sugar and backbone modifications to inhibit nuclease degradation. However, metabolic stabilization by phosphorothioate (PS), the only backbone chemistry used clinically, may be insufficient for targeting extrahepatic tissues. To improve oligonucleotide stabilization, we report the discovery, synthesis and characterization of extended nucleic acid (exNA) consisting of a methylene insertion between the 5'-C and 5'-OH of a nucleoside. exNA incorporation is compatible with common oligonucleotide synthetic protocols and the PS backbone, provides stabilization against 3' and 5' exonucleases and is tolerated at multiple oligonucleotide positions. A combined exNA-PS backbone enhances resistance to 3' exonuclease by ~32-fold over the conventional PS backbone and by >1,000-fold over the natural phosphodiester backbone, improving tissue exposure, tissue accumulation and efficacy in mice, both systemically and in the brain. The improved efficacy and durability imparted by exNA may enable therapeutic interventions in extrahepatic tissues, both with siRNA and with other oligonucleotides such as CRISPR guide RNA, antisense oligonucleotides, mRNA and tRNA.
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Affiliation(s)
- Ken Yamada
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA.
| | - Vignesh N Hariharan
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jillian Caiazzi
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Rachael Miller
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Chantal M Ferguson
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Ellen Sapp
- Department of Neurology, Harvard Medical School and Mass General Institute for Neurodegenerative Disease, Charlestown, MA, USA
| | - Hassan H Fakih
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Qi Tang
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Nozomi Yamada
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Raymond C Furgal
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Joseph D Paquette
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Annabelle Biscans
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Brianna M Bramato
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Nicholas McHugh
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Ashley Summers
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Clemens Lochmann
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Bruno M D C Godinho
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Samuel Hildebrand
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | | | - Dimas Echeverria
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Matthew R Hassler
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Julia F Alterman
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Marian DiFiglia
- Department of Neurology, Harvard Medical School and Mass General Institute for Neurodegenerative Disease, Charlestown, MA, USA
| | - Neil Aronin
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Anastasia Khvorova
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA, USA.
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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Pal C, Richter M, Rozners E. Synthesis and Properties of RNA Modified with Cationic Amine Internucleoside Linkage. ACS Chem Biol 2024; 19:249-253. [PMID: 38314716 PMCID: PMC11058646 DOI: 10.1021/acschembio.3c00784] [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: 02/07/2024]
Abstract
Chemical modifications of RNA are important tools for the development of RNA therapeutics. The present study reports a novel RNA backbone modification that replaces the negatively charged phosphate with a positively charged amine linkage. Despite being thermally destabilizing in RNA duplexes, the amine linkage caused a relatively modest decrease of activity of a modified short interfering RNA (siRNA). At position 2 of the guide strand, the amine modification strongly enhanced the specificity of siRNA while causing an ∼5-fold drop of on-target activity. These results support the future development of amines as cationic RNA modifications and novel tools to modulate protein-RNA interactions.
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Affiliation(s)
- Chandan Pal
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Michael Richter
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
| | - Eriks Rozners
- Department of Chemistry, Binghamton University, The State University of New York, Binghamton, New York 13902, United States
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Osawa T, Akino T, Obika S. Synthesis, Duplex-Forming Ability, and Enzymatic Stability of Oligonucleotides Modified with Amide-Linked Dinucleotides Containing a 3',4'-Tetrahydropyran-Bridged Nucleic Acid. J Org Chem 2024; 89:269-280. [PMID: 38064209 DOI: 10.1021/acs.joc.3c02019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
Replacement of a phosphodiester linkage with an amide linkage can improve the binding affinity of oligonucleotides to complementary RNA and their stability toward nucleases. In addition, restricting the conformation of the sugar moiety and the phosphate backbone in oligonucleotides effectively improves duplex stability. In this study, we designed amide-linked dinucleotides containing a 3',4'-tetrahydropyran-bridged nucleic acid (3',4'-tpBNA) with a constrained sugar conformation as well as a torsion angle ε. Phosphoramidites of the designed dinucleotides were synthesized and incorporated into oligonucleotides. Conformational analysis of the synthesized dinucleotides showed that the sugar conformation of the S-isomer of the amide-linked dinucleotide containing 3',4'-tpBNA was N-type, which has the same conformation as that of the RNA duplex, while that of another R-isomer was S-type. Tm analysis indicated that the oligonucleotides containing the synthesized S-isomer showed RNA-selective hybridizing ability, although their duplex-forming ability was slightly inferior to that of natural oligonucleotides. Interestingly, the stability of the oligonucleotides toward endonucleases was significantly improved by modification with the two types of amide-linked dinucleotides developed in this study.
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Affiliation(s)
- Takashi Osawa
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Taiki Akino
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Satoshi Obika
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan
- Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Yamadaoka 1-3, Suita, Osaka 565-0871, Japan
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Desaulniers JP, Tsubaki K, Hammill ML, Kitamura M, Okauchi T. Synthesis of Dinucleotide Non-Symmetrical Triester Phosphate Phosphoramidites and Their Incorporation Within Oligonucleotides. Curr Protoc 2023; 3:e784. [PMID: 37219041 DOI: 10.1002/cpz1.784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this protocol article, the synthesis of dinucleotide non-symmetrical triester phosphate phosphoramidites will be highlighted. Specifically, we use a selective transesterification starting with tris(2,2,2-trifluoroethyl) phosphate to afford a dinucleotide derivative phosphate ester. Substitution of the final trifluoroethyl group with various alcohols affords a dinucleotide triester phosphate with a hydrophobic group, which can then be deprotected and converted to a phosphoramidite for incorporation within oligonucleotides. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Synthesis of a DMT- and TBS-protected unsymmetrical dinucleotide Basic Protocol 2: Synthesis of a DMT-protected unsymmetrical dinucleotide phosphotriester monoalcohols Basic Protocol 3: Synthesis of DMT-protected phenylethyl phosphotriester dinucleotide phosphoramidites Basic Protocol 4: Synthesis, purification, and characterization of RNAs containing triester phosphate modifications.
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Affiliation(s)
- Jean-Paul Desaulniers
- University of Ontario Institute of Technology, Faculty of Science, Oshawa, Ontario, Canada
| | - Kouta Tsubaki
- University of Ontario Institute of Technology, Faculty of Science, Oshawa, Ontario, Canada
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu Institute of Technology, Tobata, Kitakyushu, Japan
| | - Matthew L Hammill
- University of Ontario Institute of Technology, Faculty of Science, Oshawa, Ontario, Canada
| | - Mitsuru Kitamura
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu Institute of Technology, Tobata, Kitakyushu, Japan
| | - Tatsuo Okauchi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu Institute of Technology, Tobata, Kitakyushu, Japan
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