Key result
In vitro fusion into mosaic myotubes restores a normal contractile phenotype using few normal myonuclei.
A small proportion of normal myonuclei is sufficient to rescue the contractile defect in muscular dysgenesis mosaic myotubes in vitro.
Minimal normal nuclei may rescue contraction in mosaic myotubes; leaves open in vivo translation and human muscular dystrophy applications.
Muscular dysgenesis (mdg) in the mouse is an autosomal recessive lethal disorder that is manifested by a gross failure of skeletal muscle development. In vitro mdg/mdg myoblasts proliferate normally and fuse successfully into myotubes, but these myotubes fail to contract either spontaneously or in response to physiological stimuli despite the presence of effective contractile elements and an ability to propagate action potentials normally. We have determined that mdg/mdg and +/+ myoblasts are capable of fusing in vitro to form "mosaic" myotubes which typically express an apparently normal contractile phenotype. Electrophoretic analysis of the relative activities of myotube glucosephosphate isomerase (GPI-1) isozymes provided a means of estimating the proportions of myonuclei of each genotype within individual myotubes. Only a very small proportion of genotypically normal myonuclei were required for expression of an apparently normal contractile phenotype.
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Peterson et al. (1984) studied Muscular dysgenesis (mdg). Fusion of mdg/mdg and +/+ myoblasts into mosaic myotubes vs. mdg/mdg myotubes was evaluated on Contractile phenotype expression. In vitro fusion of mdg/mdg and +/+ myoblasts into mosaic myotubes restored an apparently normal contractile phenotype, requiring only a very small proportion of genotypically normal myonuclei.
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