Supplementary Figure 12: Analysis of off-target editing sites with attenuated editing upon ASO treatment.

a) Five editing sites, all located in Alu sequences, were found to be significantly less edited in ASO-transfected, IFN-α-treated cells compared to the control lacking ASO transfection (but treated with IFN-α), N=2 independent experiments. b) and c) The regions around the off-target sites were aligned to the ASO-interacting region (40 nt) of the GAPDH transcript using MUSCLE (ebi.ac.uk/tools/msa/muscle/). The red A indicates the respective edited site and nucleotides matching with the ASO target sequence on GAPDH are highlighted in turquois. For the most strongly affected site (MAGT1), but also for the other four sites, the ASO seems to be able to bind tightly in proximity to the respective editing sites and therefore interrupt the dsRNA secondary structure of the Alu repeat, which is required for editing. This suggests that the attenuated editing found at those sites is caused by direct interaction of the ASO with the off-target transcript and is not due to a global sequestering of the ADAR enzyme by the ASO.