Figure 5
Ectopic Dpp signaling induces apoptosis. (A) him-GFP reporter is expressed in muscle and heart precursors in control 69B-gal4 drivers at stage 14. (B) The expression of him- GFP reporter was confined to cardial and pericardial cells at stage 16. (C-F) Overexpression of dpp in ectoderm using 69B-gal4 driver mimicked the raw mutant phenotype. (C) Ectodermal expression of dpp resulted in naked cuticle with dorsal open phenotype. (D) Cardiac him- GFP was overexpressed in embryos overexpressing dpp at stage 14 (brackets). (E) Cardial and muscular him- GFP was lost in embryos overexpressing dpp at stage 16. (F) Ectopic dpp induced excessive cell death. (G) Overexpression of tkvCA using 24B-gal4 increased the expression of him- GFP reporter at stage 14. (H) The expression of him- GFP was abolished in embryos overexpressing tkvCA at stage 16. (I) Normal developmental PCD revealed by AO staining in control 24B-gal4 driver. (J) AO-positive cells were moderately increased in tkv7 mutant embryos. (K) RNAi silenced tkv under the control of 24B-gal4 induced apoptosis. (L) Mesodermal overexpression of tkvCA caused excessive cell death. (M) Scattered AO-positive cells were present in tkv7; raw1 double mutant embryos. Note that the mutant embryos did not exhibit cardial apoptosis, but showed a dorsal open phenotype. (N) Mesodermal knockdown of the expression of tkv suppressed cardial apoptosis in raw mutant. (O-U) Ectopic dpp-induced apoptosis was dose-dependent. (P-R) Control Act5C-gal4 driver showed normal AO staining pattern at different temperatures: (P, S) 18°C; (Q, T) 25°C; (R, U) 30°C. (S-U) Constitutive overexpression of dpp induced apoptosis. (O) Dead cells were quantified and expressed as the mean ± SD values. Comparison of dead cells among three groups was assessed by one-way analysis of variance (ANOVA) followed by Dunnett's post-hoc test (n = 15). * indicates p < 0.05; ** indicates p < 0.001. WT, wild-type; st, stage.