Specific -promoter targeting by CRISPRi reverses myotonic dystrophy type 1-associated defects in patient muscle cells.

Myotonic dystrophy type 1 (DM1) is a neuromuscular disease that originates from an expansion of CTG microsatellites in the 3' untranslated region of the gene, thus leading to the expression of transcripts containing expanded CUG repeats (). The pathophysiology is explained by a toxic RNA gain of function where RNAs form nuclear aggregates that sequester and alter the function of MBNL splicing factors, triggering splicing misregulation linked to the DM1 symptoms. There is currently no cure for DM1, and most therapeutic strategies aim at eliminating transcripts. Here, we investigate a -promoter silencing strategy using CRISPR interference as a new alternative approach. Different sgRNAs targeting the promoter are evaluated in DM1 patient muscle cells. The most effective guides allowed us to reduce the level of transcripts and -RNA aggregates up to 80%. The repression corrects the overall transcriptome, including spliceopathy, and reverses a physiological parameter in DM1 muscle cells. Its action is specific and restricted to the gene, as confirmed by genome-wide expression analysis. Altogether, our findings highlight -promoter silencing by CRISPRi as a promising therapeutic approach for DM1.