A Decoy-Based Gene Therapy to Inhibit RNA Toxicity Associated with Expanded CUG
Résumé
"Introduction: Nuclear-retained CUGexp-DMPK transcripts sequester MBNL splicing factor hampering its alternative splicing regulatory function. Here, we develop a novel strategy using an engineered MBNL∆ protein aimed to act as a CUGexp-decoy.
Methods: WT and DM1 myoblasts expressing MBNL∆ lacking splicing activity but keeping RNA binding property. WT and HSALR mice injected with AAV-MBNL∆ vectors.
Results: In vitro, we showed that MBNL∆ binds to CUGexp-DMPK transcripts and displaces MBNL1 from foci in DM1 muscle cells. The subsequent recovery of functional MBNL1 allows an overall reversal of the disease transcriptome. In vivo, intramuscular injection of AAV-MBNL∆ vectors in HSALR mice results in a complete and durable normalization of splicing misregulation and myotonia, up to one year. Systemic delivery of AAV9-MBN∆ in adult HSALR mice leads also to the correction of splicing defects and myotonia in skeletal muscles.
Conclusion: Our results support this decoy-based gene therapy approach as therapeutic intervention for DM1."