Correction of dystrophia myotonica type 1 pre-mRNA transcripts by artificial trans-splicing

Dystrophia myotonica type 1 (DM1), the most common muscular dystrophy in adults, results from expansion of a CTG repeat in the 3'-untranslated region of the dystrophia myotonica protein kinase gene (DMPK). Correction of the mutant DMPK transcript is a potential therapeutic strategy in DM1. We investigated the efficacy of artificial trans-splicing molecules (ATMs) to target and correct DMPK transcripts. ATMs designed to target intron 14 of DMPK pre-mRNA transcripts were tested for their ability to trans-splice the transcripts of a DMPK mini-gene construct and the endogenous DMPK transcripts of human myosarcoma cells (CCL-136). On agarose gel electrophoresis analysis, six of eight ATMs showed trans-splicing efficacy when applied to DMPK mini-gene construct transcripts, of which three were able to trans-splice endogenous DMPK pre-mRNA transcripts in myosarcoma cells, with trans-splicing efficiency ranging from 1.81 to 7.41%. These findings confirm that artificial trans-splicing can repair DMPK pre-mRNA and provide proof-of-principle evidence for this approach as potential therapeutic strategy for DM1.