Figure 3.

The reaper Promoter Integrates Inputs from JNK and Dpp Signaling

(A) Diagram of the reporter constructs that were tested in transgenic embryos; 5.5 kb of the reaper promoter were used to create rpr-GFP. Predicted binding sites for Schnurri or AP-1 were mutated to generate the variants listed. Details of the mutations are indicated in the text.

(B) The unmutated reporter (rpr-GFP) is almost silent in wild-type embryos. En, Engrailed.

(C) In crumbs mutant embryos, the same reporter is active in the ventrolateral, but not the dorsal (double-headed arrow), epidermis.

(D) By contrast, in schnurri mutants, rpr-GFP becomes active in the dorsal epidermis, suggesting that Schnurri is an essential repressive factor.

(E) Embryos lacking both crumbs and schnurri upregulate rpr-GFP throughout much of the epidermis.

(F) Mutation of the predicted Schnurri binding site leads to upregulation of the reporter in the dorsal epidermis wild-type embryos at stage 13.

(G) In crumbs mutant embryos, rpr[ΔShn]-GFP upregulation is seen in the dorsal epidermis (double-headed arrow) as well as in the ventrolateral epidermis, consistent with the notion that Schnurri contributes to preventing reaper expression in the dorsal epidermis of crumbs embryos.

(H–J) Upregulation of the reaper reporter in crumbs mutants requires the two predicted AP-1 binding sites. Deletion of either site leads to reduced expression while the double mutant reporter (rpr[ΔAP1^D; ΔAP1^P]-GFP) is silent.

(K) Gamma-irradiated embryos carrying the rpr[ΔAP1^D; ΔAP1^P]-GFP transgene express GFP throughout, showing that this reporter is functional.

All embryos are shown at stage 11 except for (F), which shows a stage 12–13 embryo. Engrailed (En), shown in white, provides an indication of the embryos’ overall morphology.