2 Drosophila Myogenesis and insights into the Role of nautilus

Several aspects of muscle development appear to be conserved between Drosophila and vertebrate organisms. Among these is the conservation of genes that are critical to the myogenic process, including transcription factors such as “nautilus.” Drosophila is a useful organism for the identification of molecules that are essential for myogenesis in both Drosophila and in other species. Nautilus appears to be involved in the specification and/or differentiation of a specific subset of muscle founder cells. As with several of its vertebrate and invertebrate counterparts, it is capable of inducing a myogenic program of differentiation reminiscent of that of somatic muscle precursors, when expressed in other cell types. Studies have revealed a critical role for Pax-3 in specifying a particular subset of myogenic cells, the progenitors of the limb muscles. These myogenic cells migrate from the somite into the periphery of the organism, where they differentiate. These myoblasts do not express MyoD or myf5 until they have arrived at their destination and begin the morphologic process of myogenesis. They then begin to express these genes, possibly to put the myogenic plan into action. Thus, as with nautilus, MyoD and myf5 may be necessary for the manifestation of a muscle-specific commitment that has already occurred.