Abstract
Upregulation of endogenous utrophin offers great promise for treating DMD, as it can functionally compensate for the lack of dystrophin caused by DMD gene mutations, without the immunogenic concerns associated with delivering dystrophin. However, post-transcriptional repression mechanisms targeting the 5′ and 3′ untranslated regions (UTRs) of utrophin mRNA significantly limit the magnitude of utrophin upregulation achievable by promoter activation. Using a utrophin 5′3′UTR reporter assay, we performed a high-throughput screen (HTS) for small molecules capable of relieving utrophin post-transcriptional repression. We identified 27 hits that were ranked using an algorithm that we designed for hit prioritization that we call Hit to Lead Prioritization Score (H2LPS). The top 10 hits were validated using an orthogonal assay for endogenous utrophin expression. Evaluation of the top scoring hit, Trichostatin A (TSA), demonstrated utrophin upregulation and functional improvement in the mdx mouse model of DMD. TSA and the other small molecules identified here represent potential starting points for DMD drug discovery efforts.
Highlights
Upregulation of endogenous utrophin offers great promise for treating DMD, as it can functionally compensate for the lack of dystrophin caused by DMD gene mutations, without the immunogenic concerns associated with delivering dystrophin
DMD patients are typically diagnosed in early childhood and become increasingly wheelchair dependent in their teens, with cardiac and respiratory failure being the major causes of morbidity and mortality[4,5,6]
We developed and applied a two-step pipeline which uses cluster analysis to group molecules with similar activity profiles, and ranks them according to an automated Hit 2 Lead Performance Score (H2LPS) algorithm based on efficacy, potency and specificity
Summary
Upregulation of endogenous utrophin offers great promise for treating DMD, as it can functionally compensate for the lack of dystrophin caused by DMD gene mutations, without the immunogenic concerns associated with delivering dystrophin. Evaluation of the top scoring hit, Trichostatin A (TSA), demonstrated utrophin upregulation and functional improvement in the mdx mouse model of DMD. With early intervention, they have been shown to increase life span of patients[11] Their use is associated with extensive side effects and toxicities exemplified by immune suppression, osteoporosis, and weight gain. Www.nature.com/scientificreports the read-through of premature stop codons and correcting mutations using gene editing[17,18] All these approaches are mutation-specific and would be applicable to restricted subsets of DMD patients. An alternate strategy for a DMD-specific therapy that in principle would be applicable to all patients would be to increase the expression of the autosomal-encoded dystrophin-related protein homolog, utrophin[19,20]. Expression of truncated[22,23,24] or full-length[25] utrophin significantly ameliorates the phenotype of mdx mice and provides the rationale for harnessing pharmacological upregulation of endogenous utrophin as a therapeutic strategy for DMD
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