Impact of depleting SR proteins on CLK1 exon 4 splicing. (A) HCT116 cells were transfected with a collection of plasmids to promote CRISPR/Cas9 modification of genes encoding various SR proteins. Following extensive validation by DNA sequencing, quantitative RT-PCR and immunoblots, cell lines that did not express the cognate SR proteins were tested for CLK1 exon 4 splicing by end point RT-PCR analysis. PSI value for each sample was obtained and compared with a derivative HCT116 cell line made with an empty vector to produce the ΔPSI values for CLK1 exon 4. (B) We used shRNA-expressing and shSCRAMBLE adenovirus vectors to deplete SRSF3 in HCT116 cells. The ΔPSI value is indicated in the graph. Statistical significance was evaluated using multiple t-test analysis. (*) P < 0.05, (**) P < 0.01, and (***) P < 0.001. Replicates for each sample displaying the RT-PCR reactions are shown in Supplemental Figure S1C.
