Figure 3.

Phosphorothioate-Mediated Antisense Strand Terminal Stabilization, Not Enhanced Cellular Uptake, Contributes to Productive Silencing Efficacy

(A) HeLa cells were treated with different hsiRNAs (0.25 μM), fixed at the indicated time points, and imaged on widefield fluorescence microscopy (n = 75–100 images per hsiRNA per time point; see Materials and Methods). Scale bars, 100 μm. (B) Quantification of cellular uptake kinetic from (A) fit to a semi-log line. Shaded area indicates 95% confidence interval. (C) Seven-point dose response performed in HeLa cells. HTT mRNA levels were quantified by QuantiGene Assay (Thermo Fisher) after 72 h treatment with hsiRNA. Representative data shown as mean ± SD (n = 3 technical replicates) from at least two independent experiments. hsiRNA (parent sequence) data are the same data in Figure 2 and are shown again for reference. UNT, untreated. ∗p < 0.05, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001 (two-way ANOVA, compared to hsiRNA [parent]).