Identification of a Zebrafish Model of Muscular Dystrophy

Abstract

1. Large-scale mutagenic screens of the zebrafish genome have identified a number of different classes of mutations that disrupt skeletal muscle formation. Of particular interest and relevance to human health is a class of recessive lethal mutations in which muscle differentiation occurs normally, but is followed by tissue-specific degeneration reminiscent of human muscular dystrophies. 2. We have shown that one member of this class of mutations, sapje (sap), results from mutations within the zebrafish orthologue of the human Duchenne muscular dystrophy (DMD) gene. Mutations in this locus cause Duchenne or Becker muscular dystrophies in human patients and are thought to result in a dystrophic pathology by disrupting the link between the actin cytoskeleton and the extracellular matrix in skeletal muscle cells. 3. We have found that the progressive muscle degeneration phenotype of sapje-mutant zebrafish embryos is caused by the failure of somitic muscle attachments at the embryonic myotendinous junction (MTJ). 4. Although a role for dystrophin at the MTJ has been postulated previously and MTJ structural abnormalities have been identified in the dystrophin-deficient mdx mouse model, in vivo evidence of pathology based on muscle attachment failure is thus far lacking. Therefore, the sapjre mutation may provide a model for a novel pathological mechanism of Duchenne muscular dystrophy and other muscle diseases. In the present review, we discuss this finding in light of previously postulated models of dystrophin function.

MicroRNA-199a is induced in dystrophic muscle and affects WNT signaling, cell proliferation, and myogenic differentiation

“…The sapje fish line has been described previously. 16,54 The Tg(mylz2-miR-199a-5p) Tg zebrafish were generated by injecting a modified version pKSGM2f plasmid that contained the 2 kb mylz2 5 0 upstream promoter sequence as described elsewhere. 55 A 0.5-kb amplicon containing the zebrafish miR-199-2 genomic sequence was cloned by PCR into the BamH1 and HindIII restriction sites and the final plasmid construct was linearized by Not1 restriction digestion.…”

“…The sapje dystrophinmutant zebrafish model is an excellent tool for studying dystrophic-muscle and disease progression, as the sapje mutants show dystrophic disease severity and can be analyzed in large numbers in a short period of time. 16,17 The sapje dystrophic zebrafish has a more severe muscle phenotype in which their dorsal muscles progressively waste resulting in significant early lethality as compared with mdx mouse models. [16][17][18] The sapje zebrafish have weakened and degenerating muscle and the majority of mutants (95%) expire by 10 dpf due to the inability to swim and oxygenate their muscles.…”

“…16,17 The sapje dystrophic zebrafish has a more severe muscle phenotype in which their dorsal muscles progressively waste resulting in significant early lethality as compared with mdx mouse models. [16][17][18] The sapje zebrafish have weakened and degenerating muscle and the majority of mutants (95%) expire by 10 dpf due to the inability to swim and oxygenate their muscles. Thus, we chose to utilize the sapje dystrophic zebrafish as a model for analyzing dysregulated dystrophic miRNAs and to expand our previous findings obtained from DMD muscle biopsies.…”

Dystrophin deficiency in Drosophila reduces lifespan and causes a dilated cardiomyopathy phenotype

“…Model organisms have been used extensively for studying the MD pathology (mdx-mouse, dog, hamster, Caenorhabditis elegans and zebra fish (see Gieseler et al, 2000;Watchko et al, 2002;Bassett & Currie, 2004). These animal models of muscular dystrophies have been complicated by gene redundancy, which can substitute at least in part for the deleted or mutated gene (e.g.…”

Analysis of Zebrafish Larvae Skeletal Muscle Integrity with Evans Blue Dye

“…Due to the fact that most muscular dystrophies result from mutations in proteins that participate in the link between the extracellular matrix and the sarcolemmal cytoskeleton, a common observation at the cellular level is the loss of sacrolemmal integrity 8,9 . This understanding of the primary pathomechanism(s) associated with muscular dystrophies is the product of numerous years of research employing animal model systems 2,[10][11][12][13][14][15] . However, despite advances in the field, there are still limited therapeutic options for treatment or management of the range of dystrophy subtypes.…”