Fig. 1.

Small molecule splicing modifiers act directly on the RNA splicing process. a, b, c RT-PCR analysis of SMN2 mRNA FL and ∆7 relative transcript levels in SMA type 1 patient fibroblasts. SMN-C3 compound activity after 6 h treatment was investigated in the presence or absence of inhibitors of splicing or polyadenylation, namely 50 µM isogingketin a, 100 nM pladienolide B b, or 40 µM cordycepin c. d Coomassie gel after chemical proteomics showing proteins pulled down in the presence of Active vs. Inactive compound, as well as after RNase treatment. The full gel is illustrated in Supplementary Fig. 2H. e Pathway enrichment analysis of Active compound (SMN-C6), suggesting highest enrichment of mRNA splicing complexes by Active, together with other categories. Removal of ribosomal proteins from the list confirmed a selective enrichment of proteins involved in mRNA splicing or nucleotide binding. Data in a, b, c represent means ± standard error of the mean (SEM) of at least nine independent assessments per concentration