- A large-scale chemical modification screen identifies design
rules to generate siRNAs with high activity, high stability and
low toxicity (2009) - The use of chemically synthesized short
interfering RNAs (siRNAs) is currently the method of choice to
manipulate gene expression in mammalian cell culture, yet
improvements of siRNA design is expectably required for
successful application in vivo. Several studies have aimed at
improving siRNA performance through the introduction of chemical
modifications but a direct comparison of these results is
difficult. We have directly compared the effect of 21 types of
chemical modifications on siRNA activity and toxicity in a total
of 2160 siRNA duplexes. We demonstrate that siRNA activity is
primarily enhanced by favouring the incorporation of the
intended antisense strand during RNA-induced silencing complex
(RISC) loading by modulation of siRNA thermodynamic asymmetry
and engineering of siRNA 3-overhangs. Collectively, our results
provide unique insights into the tole