Regulation of digitoxin target exons by SRp20 and Tra2-β. (A) shRNA-mediated knockdown of SRp20 and Tra2-β in HEK293 cells. Number below each blot shows relative expression level normalized to GAPDH and β-tubulin. (B) OmniViewer analysis for changes in alternative cassette exons in the two knockdown conditions compared with control. (C) Representative RT-PCR gels for alternative splicing changes. (D) APP exon 8 is the second exon of a dual cassette exon pair with exon 7. It possesses a consensus SRp20 binding site and is repressed by both digitoxin and SRp20 knockdown, but not Tra2-β knockdown. (E) RIPK2 exon 2 contains two potential Tra2-β binding sites and is repressed by digitoxin treatment and Tra2-β knockdown, but is unaffected by SRp20 knockdown. (F) ZNF207 exon 9 contains two potential SRp20 binding sites and one potential Tra2-β binding site and is repressed by digitoxin and both knockdowns.
