Abstract

Feeding is a crucial behaviour of all animals, which relies on rhythmic motor patterns triggered/elicited by specialized neural circuits. Despite its vital importance, specific determinants required for the development, wiring and connectivity of feeding-specific neuromuscular networks are largely unknown. We have identified the Hox transcription factor Deformed (Dfd) to be expressed and functional in specific motoneurons and muscles, which constitute the feeding circuit in Drosophila. Using genetic, molecular, genomic and behavioural approaches we show that Dfd is needed at subsequent steps of the wiring program by directly controlling target genes with specific functions in motoneuronal specification, axon growth and synapse development. Moreover, the synchronous regulation of neuromuscular target recognition molecules in feeding-associated motoneurons and muscles indicates a role of Dfd in coordinating the interdependent events of feeding circuit formation. We finally demonstrate that the Dfd homolog Hoxb4 is expressed in motoneurons innervating jaw muscles in the vertebrate model medaka, thereby providing the framework for examining the potentially conserved role of paralogy group 4 Hox genes in feeding circuitry establishment.