Overexpression of SR proteins modulates endogenous <i>SMN2</i> exon 7 inclusion in cells.

<p>(<b>A</b>) Semi-quantitative radiolabelled RT-PCR of endogenous <i>SMN2</i> mRNA following selective over-expression of SR proteins in HeLa cells. Reaction products were digested with DdeI to distinguish between <i>SMN1</i> and <i>SMN2</i> transcripts, digestion products are indicated on the left. Mock samples were exposed to the transfection reagent in the absence of siRNA. (<b>B</b>) The graph represents quantification of <i>SMN2</i> exon 7 inclusion: (Exon 7 included/skipped). Asterisks indicate a statistically significant decrease in exon 7 inclusion p≤0.05 and **p≤0.01, by unpaired Student’s t tests. Error bars represent SEM. In all cases, SRSF1, SRSF2, SRSF3, SRSF4, SRSF5, SRSF6, SRSF7, SRSF9 n = 6; SRSF11 n = 5. (<b>C</b>) Immunoblot analysis of protein lysates from HeLa cells transfected with the indicated expression vectors. Immunoblots of T7-tagged SRSF1, SRSF2, SRSF3, SRSF7, and SRSF9 probed with a T7-specific antibody, endogenous SRSF4, 5 and 6 probed with SRSF4-, SRSF5- and SRSF6-specific antibodies and FLAG-tagged SRSF11 probed with a FLAG-specific antibody. β-actin and β-catenin were analyzed for loading control.