CRISPR/Cas Applications in Myotonic Dystrophy: Expanding Opportunities

• Published in: International journal of molecular sciences 2019-07, Vol.20 (15), p.3689
• Main Authors: Raaijmakers, Renée H L, Ripken, Lise, Ausems, C Rosanne M, Wansink, Derick G
• Format: Article
• Language: English
• Subjects: Animals; Cell cycle; cell therapy; Cell- and Tissue-Based Therapy; Chemical compounds; CRISPR; CRISPR-Cas Systems; Deoxyribonucleic acid; Disease; DNA; DNA methylation; Domains; Dystrophy; Fluorescence; Fluorophores; Gene Editing; Gene Targeting; gene therapy; Genetic Association Studies; Genetic Loci; Genetic modification; Genetic Predisposition to Disease; Genetic Therapy; Genomes; Green fluorescent protein; Humans; Laboratories; muscular dystrophy; Mutation; Myotonic dystrophy; Myotonic Dystrophy - genetics; Myotonic Dystrophy - therapy; neuromuscular disease; Nuclease; Open reading frames; Polyglutamine; Proteins; repeat expansion; Review; Transcription factors; trinucleotide repeat; Trinucleotide Repeat Expansion; Trinucleotide Repeats
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms20153689

CRISPR/Cas technology holds promise for the development of therapies to treat inherited diseases. Myotonic dystrophy type 1 (DM1) is a severe neuromuscular disorder with a variable multisystemic character for which no cure is yet available. Here, we review CRISPR/Cas-mediated approaches that target the unstable (CTG•CAG)n repeat in the / gene pair, the autosomal dominant mutation that causes DM1. Expansion of the repeat results in a complex constellation of toxicity at the DNA level, an altered transcriptome and a disturbed proteome. To restore cellular homeostasis and ameliorate DM1 disease symptoms, CRISPR/Cas approaches were directed at the causative mutation in the DNA and the RNA. Specifically, the triplet repeat has been excised from the genome by several laboratories via dual CRISPR/Cas9 cleavage, while one group prevented transcription of the (CTG)n repeat through homology-directed insertion of a polyadenylation signal in . Independently, catalytically deficient Cas9 (dCas9) was recruited to the (CTG)n repeat to block progression of RNA polymerase II and a dCas9-RNase fusion was shown to degrade expanded (CUG)n RNA. We compare these promising developments in DM1 with those in other microsatellite instability diseases. Finally, we look at hurdles that must be taken to make CRISPR/Cas-mediated editing a therapeutic reality in patients.