Details

Autor(en) / Beteiligte

• Schlegel, Mark K
• Matsuda, Shigeo
• Brown, Christopher R
• Harp, Joel M
• Barry, Joseph D
• Berman, Daniel
• Castoreno, Adam
• Schofield, Sally
• Szeto, John
• Manoharan, Muthiah
• Charissé, Klaus
• Egli, Martin
• Maier, Martin A

Titel

Overcoming GNA/RNA base-pairing limitations using isonucleotides improves the pharmacodynamic activity of ESC+ GalNAc-siRNAs

Ist Teil von

• Nucleic acids research, 2021-11, Vol.49 (19), p.10851

Ort / Verlag

England

Erscheinungsjahr

2021

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• We recently reported that RNAi-mediated off-target effects are important drivers of the hepatotoxicity observed for a subset of GalNAc-siRNA conjugates in rodents, and that these findings could be mitigated by seed-pairing destabilization using a single GNA nucleotide placed within the seed region of the guide strand. Here, we report further investigation of the unique and poorly understood GNA/RNA cross-pairing behavior to better inform GNA-containing siRNA design. A reexamination of published GNA homoduplex crystal structures, along with a novel structure containing a single (S)-GNA-A residue in duplex RNA, indicated that GNA nucleotides universally adopt a rotated nucleobase orientation within all duplex contexts. Such an orientation strongly affects GNA-C and GNA-G but not GNA-A or GNA-T pairing in GNA/RNA heteroduplexes. Transposition of the hydrogen-bond donor/acceptor pairs using the novel (S)-GNA-isocytidine and -isoguanosine nucleotides could rescue productive base-pairing with the complementary G or C ribonucleotides, respectively. GalNAc-siRNAs containing these GNA isonucleotides showed an improved in vitro activity, a similar improvement in off-target profile, and maintained in vivo activity and guide strand liver levels more consistent with the parent siRNAs than those modified with isomeric GNA-C or -G, thereby expanding our toolbox for the design of siRNAs with minimized off-target activity.