Parallel Assessment Of Silencing Potency Of Conventional Sirnas Vs. Dicer Substrate Interfering Rnas

RNA interference (RNAi) is a sequence specific gene silencing mechanism that can decrease the expression of target proteins. RNAi's sequence specificity has made it a powerful tool for cell biologists and is being developed for therapeutics. RNAi is triggered by short interfering RNA (siRNA), which are ~21bp RNA duplexes designed such that one of the strands (the guide strand (GS)) is complementary to the mRNA of the target protein. Biasing strand selection in favor of the guide strand, rather than the non‐guide strand (the passenger strand (PS)) will improve gene silencing potency. Our lab has developed longer, asymmetric, and chemically modified siRNA variants, termed Dicer substrate interfering RNA (dsiRNA). DsiRNA are engineered such that the GS is preferentially selected. Here we present a parallel screening of gene silencing ability of conventional siRNA vs. dsiRNA. Using a psiCHECK assay and calculating the 50% inhibitory concentration (IC 50 ), we found that the PS of conventional siRNA exhibited > 8‐fold lower IC50 value than the GS (IC 50 (PS) = 9.75 pM vs. IC 50 (GS) = 71.55 pM). Meanwhile, dsiRNA reduced the silencing potency of the PS (IC 50 (PS) = 24.40 pM) while simultaneously increasing the silencing potency of the GS (IC 50 (GS) = 29.90 pM). Thus, relative to conventional siRNA, the biased strand selection of the dsiRNA improves the silencing ability of the GS and reduces the silencing ability of the PS.