Prepattern genes and signaling molecules regulate stripe expression to specify Drosophila flight muscle attachment sites.

In Drosophila, muscles attach to epidermal tendon cells specified by the gene stripe (sr). Flight muscle attachment sites are prefigured on the wing imaginal disc by sr expression in discrete domains. We describe the mechanisms underlying the specification of these domains of sr expression. We show that the concerted activities of the wingless (wg), decapentaplegic (dpp) and Notch (N) signaling pathways, and the prepattern genes pannier (pnr) and u-shaped (ush) establish domains of sr expression. N is required for initiation of sr expression. pnr is a positive regulator of sr, and is inhibited by ush in this function. The Wg signal differentially influences the formation of different sr domains. These results identify the multiple regulatory elements involved in the positioning of Drosophila flight muscle attachment sites.