Fig. 3: ADAR1-mediated editing of an ISS enhances SRSF7 binding for exon skipping.

a Sequence chromatograms illustrate the editing level of the indicated sites (1–4) at intron 8 of CCDC15 pre-mRNA in HEK293T cells that were transfected with empty vector control (EV), ADAR1 (0.25, 1.0, or 2.0 µg), or ADAR2 (2.0 µg) expression construct. Black arrowhead indicates editing position. Red arrows show the location of primers used for PCR amplification. b Upper panel: schematic diagram of wild-type (WT) CCDC15 exon 8–9–10 minigene. The positions where an A-to-G mutation was introduced are highlighted in red (sites 1, 2, and 4) and purple (site 3). The 13-bp region deleted in the Del minigene is shaded in orange. Lower panel: RT-PCR analysis of exon 9 inclusion of exogenous CCDC15 transcripts in HEK293T cells that were transfected with the indicated WT or mutant minigenes (n = 3 or 2 biological replicates for each). 1 + 2 denotes both sites 1 and 2 were mutated from A to G. c In silico prediction of SRSF7 binding sites on the edited CCDC15 pre-mRNA by Human Splicing Finder (orange line) and RBPmap (blue line). The edited nucleotide at site 2 is highlighted in red. d RT-PCR analysis of exon 9 inclusion of exogenous CCDC15 transcripts in HEK293T cells that were co-transfected with WT or site 2-mutated (Mut 2) minigene together with EV or SRSF7 expression construct (n = 3 biological replicates for each). e WB analysis of RNA pulldown products (eluate) shows binding of SRSF7 and hnRNPK protein to the WT or Mut 2 RNA probes. Sequence of the Mut 2 probe is shown in c and the WT probe is the same except site 2 that remains as an unedited adenosine. FT, flow-through. b, d Data are presented as the mean ± S.D. of percent spliced in (PSI) values from biological replicates. Each dot represents a biological replicate. Statistical significance is determined by paired t-test (*P < 0.05; **P < 0.01). Source data are provided as a Source Data file.