Publication Date:
2014-06-03
Description:
Myotonic dystrophy type 1 (DM1) is a dominantly inherited neuromuscular disorder resulting from expression of RNA containing an expanded CUG repeat (CUG exp ). The pathogenic RNA is retained in nuclear foci. Poly-(CUG) binding proteins in the Muscleblind-like (MBNL) family are sequestered in foci, causing misregulated alternative splicing of specific pre-mRNAs. Inhibitors of MBNL1-CUG exp binding have been shown to restore splicing regulation and correct phenotypes in DM1 models. We therefore conducted a high-throughput screen to identify novel inhibitors of MBNL1-(CUG) 12 binding. The most active compound was lomofungin, a natural antimicrobial agent. We found that lomofungin undergoes spontaneous dimerization in DMSO, producing dilomofungin, whose inhibition of MBNL1–(CUG) 12 binding was 17-fold more potent than lomofungin itself. However, while dilomofungin displayed the desired binding characteristics in vitro , when applied to cells it produced a large increase of CUG exp RNA in nuclear foci, owing to reduced turnover of the CUG exp transcript. By comparison, the monomer did not induce CUG exp accumulation in cells and was more effective at rescuing a CUG exp -induced splicing defect. These results support the feasibility of high-throughput screens to identify compounds targeting toxic RNA, but also demonstrate that ligands for repetitive sequences may have unexpected effects on RNA decay.
Print ISSN:
0305-1048
Electronic ISSN:
1362-4962
Topics:
Biology
