Fig. 7. The Msx2 BMPRE accurately interprets Dpp signals in Drosophila. (A-D) Msx2 transgenes behave like Dpp-responsive genes in imaginal discs. In situ hybridization showing dpp expression (A). Expression of a vestigial-lacZ reporter gene, a known dpp target (B). Expression of the 480bpMsx2-lacZ transgene (C). The 480 bp fragment is the conserved region identified in Fig. 2, Fig. 3A. Expression of the 480bpMsx2-lacZ transgene in the wing pouch with ectopic activation of the Dpp pathway by A9Gal4>TkvA (D). (E-I) dpp and 220bpMsx2-lacZ transgene expression in stage 13 embryos (lateral view). dpp in situ hybridization showing wild-type expression pattern in parasegments (ps) 3 and 7 of the embryonic mid-gut (E) and in dpp (S11/S22) mutant (F), in which dpp expression is lost in ps3 (arrow), but not in ps7. 220bpMsx2-lacZ transgene in wild type (G) and dpp (S11/S22) mutant (H). Expression of 220bpMsx2-lacZ transgene throughout the gut in response to ectopic expression of Dpp driven by a heat-shock promoter (I). (J-Q) dpp and 52bpMsx2-lacZ transgene expression in early blastoderm embryos (lateral view). dpp in situ of a stage 5 embryo showing restriction of dpp expression to the dorsal part of the embryo (J). Expression of the 52bpMsx2-lacZ transgene in wild-type (K) and dorsal mutant (L) embryos. Expression of 52bpMsx2-lacZ transgene in screw (M) and brinker (O) mutant embryos, and in an embryo with ectopic activation of Dpp using Tub Gal4>UAS Dpp (N). 52bpMsx2-lacZ transgene expression is lost when the Smad sites (P) or homeodomain site (Q) are mutated.