Figure 6.

The Sequence of the Single-Stranded Phosphorothioate Tail Affects Cellular Uptake

(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). hsiRNA (parent sequence) data are the same data in Figure 2 and are shown again for reference. Scale bars, 100 μm. (B) Quantification of cellular uptake kinetic from (A) fit to a semi-log line. Shaded area indicates 95% confidence interval. Top left panel shows hsiRNA^HTT and hsiRNA^sFLT and their chimeric tail-swapped sequences, hsiRNA^HTT15/sFLT5 and hsiRNA^sFLT15/HTT5. Other panels compare only two hsiRNAs compared at a time for clarity, showing that hsiRNA^sFLT tail sequence enhances cellular uptake compared to the hsiRNA^HTT tail sequence.