Broad objectives and specific aims
To develop novel RNA-based therapy for Familial Dysautonomia (FD). To provide splicing-switching molecules based on modified U1 snRNA characterized for in vivo efficacy and safety, able to rescue, particularly in the central/peripheral sensory and autonomic nervous systems, the IKBKAP expression impaired by the IVS20+6t/c mutation.
FD is a life-threatening rare recessive disease, common in Ashkenazi Jews, characterized by poor development and degeneration of sensory/autonomic nerves. There is no cure. The exon skipping IVS20+6t/c mutation in IKBKAP gene, is the major (>99%) FD cause. Whereas the IKBKAP size and its poorly known regulation complicates replacement gene therapy, the molecular defect renders FD an ideal target for strategies promoting exon 20 inclusion. We propose to rescue exon 20 skipping using an RNA- based approaches that use modified U1 snRNA, named Exon Specific U1snRNA (ExSpeU1), aimed at improving exon definition. Preliminary data show a significant activity of one ExSpeU1 in FD patient’s cells.
Research design and methods
Rescue of aberrant IKBKAP exon 20 splicing by ExSpeU1s will be explored in minigene assays. ExSpeU1IKAP efficacy (rescue of IKBKAP expression and protein) and safety (analysis of off-targets by RNA seq) of ExSpeU1IKAP, delivered by Lentivirus will be directly evaluated in FD patients’ fibroblasts. Active and safe ExSpeU1IKAP, delivered by adenoassociated viruses (AAV9) will be tested in humanized FD mouse models for their ability to rescue IKBKAP expression and ameliorate the clinical phenotype.
To establish the in vivo efficacy/safety of the ExSpeU1 IKBKAP-specific splicing-switching molecules for the development of valid therapeutic options for FD.
Impact on patients
To cure Familial Dysautonomia we propose modified U1 snRNA splicing-switching molecules (ExSpeU1s) that, differently from other drugs under study, would specifically target the IKBKAP disease gene and counteract the major (99%) FD-causing mutation. The correction at the mRNA level that, at variance from gene therapy approaches inserting exogenous sequences that drive the expression of the missing factor, would restore gene expression while maintaining the proper transcriptional control at the natural chromosomal environment. This approach might be used to cure the FD symptoms and/or to ensure a long-life treatment (ExSpeU1 delivered by AdenoAssociated vectors). AAV-releted strategies are currently tested in clinical trials for different genetic disorders. Thus, the results in vivo from this project might boost the ExSpeU1 development to provide valid and tailored therapeutic options for this serious life-threatening disease.
Franco Pagani, Human Molecular Genetics, ICGEB Trieste, Italy