Controlling miRNA-like off-target effects of an siRNA with nucleobase modifications.Suter, S.R., Ball-Jones, A., Mumbleau, M.M., Valenzuela, R., Ibarra-Soza, J., Owens, H., Fisher, A.J., Beal, P.A.
(2017) Org. Biomol. Chem. 15: 10029-10036
- PubMed: 29164215
- DOI: 10.1039/c7ob02654d
- PubMed Abstract:
SiRNAs can cause unintended gene silencing due to miRNA-like effects because of the similarity in function of an siRNA guide strand and a miRNA. Here we evaluate the effect on miRNA-like off targeting of introducing the adenosine derivative 7-EAA and ...
SiRNAs can cause unintended gene silencing due to miRNA-like effects because of the similarity in function of an siRNA guide strand and a miRNA. Here we evaluate the effect on miRNA-like off targeting of introducing the adenosine derivative 7-EAA and triazoles prepared from 7-EAA at different positions in an siRNA guide strand. We find that a sterically demanding triazole placed in the RNA duplex major groove at position six of the guide strand dramatically reduces miRNA-like off targeting potency. A high-resolution structure of an RNA duplex bearing a novel, major-groove localized triazole is reported, which suggests that modified triazoles could be disrupting the hAgo2-guide-target RNA ternary complex. Five different triazole modifications were tested at the guide strand 6-position for effects on on-target and miRNA-like off target knockdown potency. A 7-EAA triazole bearing a benzylamine substituent displayed on-target knockdown activity as potent as the native siRNA, while having an IC50 against a miRNA-like off target >100-fold higher. Melting temperature studies revealed no obvious correlation between potency in knockdown assays and a modification's effect on duplex stability. These results, along with known structures of hAgo2-guide-target ternary complexes, are used to rationalize the effect of 7-EAA triazoles on miRNA-like off target effects.
Department of Chemistry, University of California, Davis, One Shields Ave, Davis, California, 95616 USA. firstname.lastname@example.org.