Figure 6

Theophylline can modulate alternative splicing in vitro. (A) Schematic representation of three-exon pre-mRNA substrates with varying strength of exon 2 5' ss. The sequence of first two exons and the entire intron 1 is identical to AdBPT15AG-8S. The sequence downstream of intron 2 5' ss, including BPS and exon 3 is from pRG1 [44]. The relative strength of exon 2 5' ss described here was based on the published report [45]. (B) Splicing in vitro of the panel of substrates (shown in A) displaying the effect of theophylline on the alternative splicing of exon 2. ³²P-labeled AdML0M-6M pre-mRNAs were subjected to in vitro splicing in the absence (lanes 1, 3, 5 and 7) or presence of theophylline (lanes 2, 4, 6 and 8) as described in Fig. 1. The extracted RNA was fractionated on a 13% polyacrylamide denaturing gel. Other labeling is as in Fig. 1. The internal exon 2 exclusion: inclusion ratio for each substrate in the absence or presence of theophylline is shown below each lane.