Fig. 3: Dynamic alteration of A-to-I RNA editing during myoblast differentiation.

a Alteration of A-to-I RNA editing frequency in AS-Alu1 from Day 0 (red) to 3 (blue). Data are presented as mean values ±S.D. The positions showing statistical significance [p < 0.05, determined by unpaired two-tailed t test; n = 4 (Day 0) and 3 (Day 3) biologically independent samples] are indicated by red triangles. Source data are provided in Source Supplementary Data 1. b The distribution of the A-to-I RNA editing frequency in AS-Alu1 on Days 0 and 3 is shown as box plots (center lines indicate median, box limits indicate upper and lower quartiles, whiskers indicate 1.5× interquartile range and points indicate outliers). Error bars denote S.D. Statistical significance was determined by unpaired two-tailed t test; n = 96 (Day 0) and 72 (Day 3). Source data are provided in Source Supplementary Data 1. c Sanger sequences of the 5′SS of the Alu exon in AS-Alu1 of SELENON mRNAs in differentiating Hu5/KD3 cells on the indicated days. The A-to-I RNA editing sites are boxed, with the site number shown above. d Frequency of editing site No. 46 in Hu5/KD3 cells on different differentiation days. Data are presented as mean values ±S.D.; n = 4 (Day 0 and Day 2), 5 (Day 1), and 3 (Day 3–5) biologically independent samples. Source data are provided in Source Supplementary Data 1. e Schematic model of conformational changes in SELENON pre-mRNA from the early-to-middle stage of differentiation. At the early stage, hnRNP C binds to AS-Alu1, and then S-Alu forms a double-stranded structure with AS-Alu2 or 3. A-to-I RNA editing occurs in this double strand. At the middle stage, the level of hnRNP C decreases. AS-Alu1 forms a double-stranded structure with S-Alu, which is recognized by ADAR1, which then performs A-to-I RNA editing in this double-stranded region, including the 5′SS of the Alu exon, thereby inhibiting U1 snRNA recognition. Source data and unprocessed gel images are provided in Source Data file.