The Drosophila sex determination hierarchy modulates wingless and decapentaplegic signaling to deploy dachshund sex-specifically in the genital imaginal disc

The integration of multiple developmental cues is crucial to the combinator ial strategies for cell specification that underlie metazoan development, I n the Drosophila genital imaginal disc, which gives rise to the sexually di morphic genitalia and analia, sexual identity must be integrated with posit ional cues, in order to direct the appropriate sexually dimorphic developme ntal program. Sex determination in Drosophila is controlled by a hierarchy of regulatory genes. The last known gene in the somatic branch of this hier archy is the transcription factor doublesex (dsx); however, targets of the hierarchy that play a role in sexually dimorphic development have remained elusive, We show that the gene dachshund (dac) is differentially expressed in the male and female genital discs, and plays sex-specific roles in the d evelopment of the genitalia. Furthermore, the sex determination hierarchy m ediates this sex-specific deployment of dac by modulating the regulation of dac by the pattern formation genes wingless (Htg) and decapentaplegic (dpp ), We find that the sex determination pathway acts cell-autonomously to det ermine whether dac is activated by wg signaling, as in females, or by dpp s ignaling, as in males.