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Updated: Dec 31, 2025
Evaluation of Exon Inclusion Induced by Splice Switching Antisense Oligonucleotides in SMA Patient Fibroblasts
Published on: May 11, 2018
Drosophila SMN2 minigene reporter model identifies moxifloxacin as a candidate therapy for SMA
Piotr Konieczny1,2,3, Rubén Artero1,2,3
1Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, Valencia, Spain.
Abstract:
Spinal muscular atrophy is a rare and fatal neuromuscular disorder caused by the loss of alpha motor neurons. The affected individuals have mutated the ubiquitously expressed SMN1 gene resulting in the loss or reduction in the survival motor neuron (SMN) protein levels. However, an almost identical paralog exists in humans: SMN2. Pharmacological activation of SMN2 exon 7 inclusion by small molecules or modified antisense oligonucleotides is a valid approach to treat SMA. Here we describe an in vivo SMN2 minigene reporter system in Drosophila motor neurons that serves as a cost-effective, feasible, and stringent primary screening model for identifying chemicals capable of crossing the conserved Drosophila blood-brain barrier and modulating exon 7 inclusion. The model was used for the screening of 1100 drugs from the Prestwick Chemical Library, resulting in 2.45% hit rate. The most promising candidate drugs were validated in patient-derived fibroblasts where they proved to increase SMN protein levels. Among them, moxifloxacin modulated SMN2 splicing by promoting exon 7 inclusion. The recovery of SMN protein levels was confirmed by increased colocalization of nuclear gems with Cajal Bodies. Thus, a Drosophila-based drug screen allowed the discovery of an FDA-approved small molecule with the potential to become a novel therapy for SMA.
Insights
A novel Drosophila model effectively screened drugs for spinal muscular atrophy (SMA). Moxifloxacin was identified as a promising compound, increasing survival motor neuron (SMN) protein levels in patient cells.
Area of Science:
- Neuroscience
- Genetics
- Pharmacology
Background:
- Spinal muscular atrophy (SMA) is a fatal neuromuscular disorder caused by reduced survival motor neuron (SMN) protein levels due to SMN1 gene mutations.
- SMN2, a human paralog, can be pharmacologically modulated to increase SMN protein and treat SMA.
Purpose of the Study:
- To develop and validate an in vivo Drosophila melanogaster model for screening compounds that modulate SMN2 exon 7 inclusion.
- To identify potential therapeutic agents for SMA by screening a chemical library using the developed Drosophila model.
Main Methods:
- An in vivo SMN2 minigene reporter system was established in Drosophila motor neurons.
- 1100 drugs from the Prestwick Chemical Library were screened for their ability to modulate SMN2 exon 7 inclusion.
- Hit compounds were validated in patient-derived fibroblasts to assess SMN protein level recovery.
Main Results:
- The Drosophila screening model identified 2.45% of tested compounds as hits.
- Moxifloxacin was identified as a promising candidate, promoting SMN2 exon 7 inclusion and increasing SMN protein levels.
- Increased colocalization of nuclear gems with Cajal Bodies confirmed SMN protein recovery in patient cells treated with moxifloxacin.
Conclusions:
- A cost-effective and feasible Drosophila-based drug screening platform was successfully developed for SMA.
- Moxifloxacin, an FDA-approved drug, demonstrated potential as a novel therapeutic agent for SMA by modulating SMN2 splicing.
