Fig. 1: MPSAs reveal IUPAC motifs for the 5’ss specificities of risdiplam and branaplam.
From: Specificity, synergy, and mechanisms of splice-modifying drugs
A, B Structures of (A) risdiplam and (B) branaplam. C MPSA performed in the context of a minigene library spanning exons 6, 7, and 8 of SMN2. In this library, the 5’ss of exon 20 was replaced by 285 variant 5’ss sequences of the form agga/GUaagu, where lower-case letters indicate mutagenized positions. D–F PSI values measured in the presence of (D) risdiplam vs. DMSO, (E) branaplam vs. risdiplam, or (F) branaplam vs. DMSO. Black dots, wild-type SMN2 exon 7 5’ss (AGGA/GUAAGU). Cyan dots, 5’ss that match the risdiplam IUPAC motif. Purple circles, 5’ss that match the hyper-activation IUPAC motif. Light green outlined areas, 5’ss classified as activated by y-axis treatment relative to x-axis treatment (class 1-ris in panel D, class 1-hyp in panel E, class 1-bran in panel F). Peach outlined areas, 5’ss classified as insensitive to y-axis treatment relative to x-axis treatment (class 2-ris in panel D, class 2-hyp in panel E, class 2-bran in panel F). MPSA, massively parallel splicing assay. 5’ss, 5’ splice site. PSI, percent spliced in. DMSO, dimethyl sulfoxide.
