7lo9

Publication Abstract from PubMed

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.

Overcoming GNA/RNA base-pairing limitations using isonucleotides improves the pharmacodynamic activity of ESC+ GalNAc-siRNAs.,Schlegel MK, Matsuda S, Brown CR, Harp JM, Barry JD, Berman D, Castoreno A, Schofield S, Szeto J, Manoharan M, Charisse K, Egli M, Maier MA Nucleic Acids Res. 2021 Nov 8;49(19):10851-10867. doi: 10.1093/nar/gkab916. PMID:34648028^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.