Interaction between apterous and early expression of vestigial in formation of the dorso‐ventral compartments in the Drosophila wing disc

Background: Compartment formation is a developmental process that requires the existence of barriers against intermixing between cell groups. In the Drosophila wing disc, the dorso‐ventral (D/V) compartment boundary is defined by the expression of the apterous (ap) selector gene in the dorsal compartment. AP activity is under control of dLMO which destabilizes the formation of the AP–CHIP complex. Results: We report that D/V boundary formation in the wing disc also depends on early expression of vestigial (vg). Our data suggest that vg is already required for wing cell proliferation before D/V compartmentalization. In addition, we show that over‐expression of vg can, to some extent, rescue the effect of the absence of ap on D/V boundary formation. Early VG product regulates AP activity by inducing dLMO and thus indirectly regulating ap target genes such as fringe and the PSα1 and PSα2 integrins. Conclusion: Normal cell proliferation is necessary for ap expression at the level of the D/V boundary. This would be mediated by vg, which interacts in a dose‐dependent way with ap.