The Hox protein Antennapedia orchestrates Drosophila adult flight muscle development.

Muscle development and diversity require a large number of spatially and temporally regulated events controlled by transcription factors (TFs). Drosophila has long stood as a model to study myogenesis due to the highly conserved key TFs involved at all stages of muscle development. While many studies focused on the diversification of Drosophila larval musculature, how distinct adult muscle types are generated is much less characterized. Here, we identify an essential regulator of Drosophila thoracic flight muscle development, the Hox TF Antennapedia (Antp). Correcting a long-standing belief that flight muscle development occurs without the input of Hox TFs, we show that Antp intervenes at several stages of flight muscle development, from the establishment of the progenitor pool in the embryo to myoblast differentiation in the early pupa. Furthermore, the precisely regulated clearance of Hox in the developing flight muscle fibers is required to allow for fibrillar muscle fate diversification, setting these muscles apart from all other adult tubular muscle types.