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Jahns H, Degaonkar R, Podbevsek P, Gupta S, Bisbe A, Aluri K, Szeto J, Kumar P, LeBlanc S, Racie T, Brown CR, Castoreno A, Guenther DC, Jadhav V, Maier MA, Plavec J, Egli M, Manoharan M, Zlatev I. Small circular interfering RNAs (sciRNAs) as a potent therapeutic platform for gene-silencing. Nucleic Acids Res 2021; 49:10250-10264. [PMID: 34508350 PMCID: PMC8501968 DOI: 10.1093/nar/gkab724] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/05/2021] [Accepted: 09/08/2021] [Indexed: 12/19/2022] Open
Abstract
In order to achieve efficient therapeutic post-transcriptional gene-silencing mediated by the RNA interference (RNAi) pathway, small interfering RNAs (siRNAs) must be chemically modified. Several supra-RNA structures, with the potential to stabilize siRNAs metabolically have been evaluated for their ability to induce gene silencing, but all have limitations or have not been explored in therapeutically relevant contexts. Covalently closed circular RNA transcripts are prevalent in eukaryotes and have potential as biomarkers and disease targets, and circular RNA mimics are being explored for use as therapies. Here we report the synthesis and evaluation of small circular interfering RNAs (sciRNAs). To synthesize sciRNAs, a sense strand functionalized with the trivalent N-acetylgalactosamine (GalNAc) ligand and cyclized using ‘click’ chemistry was annealed to an antisense strand. This strategy was used for synthesis of small circles, but could also be used for synthesis of larger circular RNA mimics. We evaluated various sciRNA designs in vitro and in vivo. We observed improved metabolic stability of the sense strand upon circularization and off-target effects were eliminated. The 5′-(E)-vinylphosphonate modification of the antisense strand resulted in GalNAc-sciRNAs that are potent in vivo at therapeutically relevant doses. Physicochemical studies and NMR-based structural analysis, together with molecular modeling studies, shed light on the interactions of this novel class of siRNAs, which have a partial duplex character, with the RNAi machinery.
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Affiliation(s)
- Hartmut Jahns
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | | | - Peter Podbevsek
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia, EU
| | - Swati Gupta
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | - Anna Bisbe
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | - Krishna Aluri
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | - John Szeto
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | - Pawan Kumar
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | - Sarah LeBlanc
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | - Tim Racie
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | | | | | | | - Vasant Jadhav
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
| | | | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia, EU
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | | | - Ivan Zlatev
- Alnylam Pharmaceuticals, Inc., Cambridge, MA 02142, USA
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Akabane-Nakata M, Erande ND, Kumar P, Degaonkar R, Gilbert JA, Qin J, Mendez M, Woods LB, Jiang Y, Janas M, O’Flaherty DK, Zlatev I, Schlegel M, Matsuda S, Egli M, Manoharan M. siRNAs containing 2'-fluorinated Northern-methanocarbacyclic (2'-F-NMC) nucleotides: in vitro and in vivo RNAi activity and inability of mitochondrial polymerases to incorporate 2'-F-NMC NTPs. Nucleic Acids Res 2021; 49:2435-2449. [PMID: 33577685 PMCID: PMC7969009 DOI: 10.1093/nar/gkab050] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 01/13/2021] [Accepted: 02/07/2021] [Indexed: 02/01/2023] Open
Abstract
We recently reported the synthesis of 2'-fluorinated Northern-methanocarbacyclic (2'-F-NMC) nucleotides, which are based on a bicyclo[3.1.0]hexane scaffold. Here, we analyzed RNAi-mediated gene silencing activity in cell culture and demonstrated that a single incorporation of 2'-F-NMC within the guide or passenger strand of the tri-N-acetylgalactosamine-conjugated siRNA targeting mouse Ttr was generally well tolerated. Exceptions were incorporation of 2'-F-NMC into the guide strand at positions 1 and 2, which resulted in a loss of the in vitro activity. Activity at position 1 was recovered when the guide strand was modified with a 5' phosphate, suggesting that the 2'-F-NMC is a poor substrate for 5' kinases. In mice, the 2'-F-NMC-modified siRNAs had comparable RNAi potencies to the parent siRNA. 2'-F-NMC residues in the guide seed region position 7 and at positions 10, 11 and 12 were well tolerated. Surprisingly, when the 5'-phosphate mimic 5'-(E)-vinylphosphonate was attached to the 2'-F-NMC at the position 1 of the guide strand, activity was considerably reduced. The steric constraints of the bicyclic 2'-F-NMC may impair formation of hydrogen-bonding interactions between the vinylphosphonate and the MID domain of Ago2. Molecular modeling studies explain the position- and conformation-dependent RNAi-mediated gene silencing activity of 2'-F-NMC. Finally, the 5'-triphosphate of 2'-F-NMC is not a substrate for mitochondrial RNA and DNA polymerases, indicating that metabolites should not be toxic.
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Affiliation(s)
| | - Namrata D Erande
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Pawan Kumar
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Rohan Degaonkar
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Jason A Gilbert
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - June Qin
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Martha Mendez
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Lauren Blair Woods
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Yongfeng Jiang
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Maja M Janas
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Derek K O’Flaherty
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Ivan Zlatev
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Mark K Schlegel
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Shigeo Matsuda
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | - Muthiah Manoharan
- Alnylam Pharmaceuticals, 675 West Kendall Street, Cambridge, MA 02142, USA
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Kumar P, Degaonkar R, Guenther DC, Abramov M, Schepers G, Capobianco M, Jiang Y, Harp J, Kaittanis C, Janas MM, Castoreno A, Zlatev I, Schlegel MK, Herdewijn P, Egli M, Manoharan M. Chimeric siRNAs with chemically modified pentofuranose and hexopyranose nucleotides: altritol-nucleotide (ANA) containing GalNAc-siRNA conjugates: in vitro and in vivo RNAi activity and resistance to 5'-exonuclease. Nucleic Acids Res 2020; 48:4028-4040. [PMID: 32170309 PMCID: PMC7192627 DOI: 10.1093/nar/gkaa125] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/15/2020] [Accepted: 03/04/2020] [Indexed: 12/23/2022] Open
Abstract
In this report, we investigated the hexopyranose chemical modification Altriol Nucleic Acid (ANA) within small interfering RNA (siRNA) duplexes that were otherwise fully modified with the 2′-deoxy-2′-fluoro and 2′-O-methyl pentofuranose chemical modifications. The siRNAs were designed to silence the transthyretin (Ttr) gene and were conjugated to a trivalent N-acetylgalactosamine (GalNAc) ligand for targeted delivery to hepatocytes. Sense and antisense strands of the parent duplex were synthesized with single ANA residues at each position on the strand, and the resulting siRNAs were evaluated for their ability to inhibit Ttr mRNA expression in vitro. Although ANA residues were detrimental at the 5′ end of the antisense strand, the siRNAs with ANA at position 6 or 7 in the seed region had activity comparable to the parent. The siRNA with ANA at position 7 in the seed region was active in a mouse model. An Oligonucleotide with ANA at the 5′ end was more stable in the presence of 5′-exonuclease than an oligonucleotide of the same sequence and chemical composition without the ANA modification. Modeling studies provide insight into the origins of regiospecific changes in potency of siRNAs and the increased protection against 5′-exonuclease degradation afforded by the ANA modification.
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Affiliation(s)
- Pawan Kumar
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Rohan Degaonkar
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Dale C Guenther
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Mikhail Abramov
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Guy Schepers
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Marie Capobianco
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Yongfeng Jiang
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Joel Harp
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
| | | | - Maja M Janas
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Adam Castoreno
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Ivan Zlatev
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Mark K Schlegel
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, MA 02142, USA
| | - Piet Herdewijn
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN 37232, USA
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