A novel chemical-combination screen in zebrafish identifies epigenetic small molecule candidates for the treatment of Duchenne muscular dystrophy

Abstract

Background Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder and is one of the most common muscular dystrophies. There are currently few effective therapies to treat the disease, although many small-molecule approaches are being pursued. Certain histone deacetylase inhibitors (HDACi) have been shown to ameliorate DMD phenotypes in mouse and zebrafish animal models. The HDACi givinostat has shown promise for DMD in clinical trials. However, beyond a small group of HDACi, other classes of epigenetic small molecules have not been broadly and systematically studied for their benefits for DMD. Methods We used an established animal model for DMD, the zebrafish dmd mutant strain sapje. A commercially available library of epigenetic small molecules was used to treat embryonic-larval stages of dmd mutant zebrafish. We used a quantitative muscle birefringence assay in order to assess and compare the effects of small-molecule treatments on dmd mutant zebrafish skeletal muscle structure. Results We performed a novel chemical-combination screen of a library of epigenetic compounds using the zebrafish dmd model. We identified candidate pools of epigenetic compounds that improve skeletal muscle structure in dmd mutant zebrafish. We then identified a specific combination of two HDACi compounds, oxamflatin and salermide, that ameliorated dmd mutant zebrafish skeletal muscle degeneration. We validated the effects of oxamflatin and salermide on dmd mutant zebrafish in an independent laboratory. Furthermore, we showed that the combination of oxamflatin and salermide caused increased levels of histone H4 acetylation in zebrafish larvae. Conclusions Our results provide novel, effective methods for performing a combination of small-molecule screen in zebrafish. Our results also add to the growing evidence that epigenetic small molecules may be promising candidates for treating DMD.

Development of a high-throughput tailored imaging method in zebrafish to understand and treat neuromuscular diseases

“…For example, the zebrafish is an excellent model for muscle pathologies ( Jagla et al, 2017 ), more adapted than mouse ( Berger and Currie, 2012 ). Models with mutations in the zebrafish dystrophin gene ( dmd and sapje models) of DMD have been developed ( Bassett and Currie, 2004 ; Guyon et al, 2009 ), whose robustness of phenotypes (muscle lesions and birefringence, almost 100% penetrant) has led to the development of a therapeutic strategy for human patients ( Johnson et al, 2013 ; Farr et al, 2020 ), which is now in phase 3 in clinical trial.…”

Modeling neuromuscular diseases in zebrafish

“…Farr et al tested epigenetic small molecules from the Cayman Chemical Epigenetics Screening Library on dmd mutant zebrafish line sapje . They developed a grid system containing 403 chemical pools, which would allow testing of each compound in the library in combination with every other library compound at least once ( Farr et al, 2020 ). Their method was validated against TSA-containing chemical pools which rescued the skeletal muscle phenotype in sapje zebrafish.…”

Epigenetic modifications in muscle regeneration and progression of Duchenne muscular dystrophy

“…In a recently published study, the authors performed a pilot screen of the commercially available Cayman Chemical Epigenetics Screening Library to identify epigenetic molecules that could improve muscle phenotype in the DMD zebrafish model. Interestingly, they proved that a novel combination of HDACi drugs, oxamflatin, and salermide significantly rescued muscle degeneration [ 266 ]. In particular, oxamflatin is an HDACi that inhibits HDACs classes I and II and is chemically similar to TSA.…”