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Updated: Dec 16, 2025
Multi-exon Skipping Using Cocktail Antisense Oligonucleotides in the Canine X-linked Muscular Dystrophy
Published on: May 24, 2016
Premature termination codons in the DMD gene cause reduced local mRNA synthesis
Raquel García-Rodríguez1, Monika Hiller1, Laura Jiménez-Gracia1
1Department of Human Genetics, Leiden University Medical Center, 2333ZA Leiden, The Netherlands.
Abstract:
Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene leading to the presence of premature termination codons (PTC). Previous transcriptional studies have shown reduced DMD transcript levels in DMD patient and animal model muscles when PTC are present. Nonsense-mediated decay (NMD) has been suggested to be responsible for the observed reduction, but there is no experimental evidence supporting this claim. In this study, we aimed to investigate the mechanism responsible for the drop in DMD expression levels in the presence of PTC. We observed that the inhibition of NMD does not normalize DMD gene expression in DMD. Additionally, in situ hybridization showed that DMD messenger RNA primarily localizes in the nuclear compartment, confirming that a cytoplasmic mechanism like NMD indeed cannot be responsible for the observed reduction. Sequencing of nascent RNA to explore DMD transcription dynamics revealed a lower rate of DMD transcription in patient-derived myotubes compared to healthy controls, suggesting a transcriptional mechanism involved in reduced DMD transcript levels. Chromatin immunoprecipitation in muscle showed increased levels of the repressive histone mark H3K9me3 in mdx mice compared to wild-type mice, indicating a chromatin conformation less prone to transcription in mdx mice. In line with this finding, treatment with the histone deacetylase inhibitor givinostat caused a significant increase in DMD transcript expression in mdx mice. Overall, our findings show that transcription dynamics across the DMD locus are affected by the presence of PTC, hinting at a possible epigenetic mechanism responsible for this process.
Insights
Duchenne muscular dystrophy (DMD) transcript levels are reduced due to premature termination codons (PTC). This study finds epigenetic changes, not NMD, affect DMD gene expression in DMD patients.
Area of Science:
- Molecular Biology
- Genetics
- Epigenetics
Background:
- Duchenne muscular dystrophy (DMD) results from DMD gene mutations causing premature termination codons (PTC).
- Reduced DMD transcript levels in DMD are linked to PTC, with nonsense-mediated decay (NMD) previously suspected but unproven.
- This study investigates the mechanism behind decreased DMD expression in the presence of PTC.
Purpose of the Study:
- To determine the mechanism responsible for reduced DMD gene expression in Duchenne muscular dystrophy.
- To experimentally test the involvement of nonsense-mediated decay (NMD) in regulating DMD transcript levels.
- To explore potential transcriptional and epigenetic factors influencing DMD expression.
Main Methods:
- Inhibition of NMD and assessment of DMD gene expression.
- In situ hybridization to determine DMD messenger RNA localization.
- Nascent RNA sequencing to analyze DMD transcription dynamics.
- Chromatin immunoprecipitation (ChIP) to evaluate histone modifications in mdx mice.
- Treatment of mdx mice with givinostat, a histone deacetylase inhibitor.
Main Results:
- NMD inhibition did not restore DMD gene expression in DMD.
- DMD messenger RNA was found to localize primarily in the nuclear compartment, excluding cytoplasmic NMD as the cause.
- DMD transcription rates were lower in patient-derived myotubes compared to controls.
- Increased H3K9me3 repressive histone marks were observed in mdx mouse muscle, suggesting altered chromatin structure.
- Givinostat treatment significantly increased DMD transcript expression in mdx mice.
Conclusions:
- Nonsense-mediated decay is not the primary mechanism reducing DMD transcript levels in Duchenne muscular dystrophy.
- Reduced DMD expression in DMD is linked to altered transcription dynamics and epigenetic modifications at the DMD locus.
- Epigenetic regulation, specifically chromatin conformation, plays a role in the reduced DMD gene expression associated with premature termination codons.
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