Dmrt2 and Pax3 double-knockout mice show severe defects in embryonic myogenesis.

Myogenesis is one of the critical developmental processes in mammals. Several transcription factors from the dermomyotome affect embryonic myogenesis. Among these, Dmrt2 and Pax3 were tested for genetic and functional interactions during embryonic myogenesis by evaluating myogenin and desmin expression patterns in Dmrt2-Pax3 mutant mouse embryos. In doubly homozygous mutant embryos, myogenin expression was reduced, and the expression pattern was altered dramatically. In Pax3-knockout mouse embryos, the pattern of Dmrt2 expression was altered, suggesting that Pax3 is important in maintaining the epaxial dermomyotome. Even though Pax3 and Dmrt2 are expressed in similar tissue- and developmental-stage-specific manners during dermomyotomal development, they appear to have independent roles in mammalian myogenesis. The processes characteristic of embryonic myogenesis are similar to those occurring during muscle regeneration in adults. Therefore, these results may provide insight into the pathogenesis of innate muscular dystrophy and may lead to the development of drugs to promote muscle repair after injury.