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. Author manuscript; available in PMC: 2011 Jun 14.
Published in final edited form as: Dev Cell. 2010 Dec 14;19(6):895–902. doi: 10.1016/j.devcel.2010.10.021

Figure 4.

Figure 4

The ecdysone-induced genetic hierarchy necessary for metamorphic development is disrupted in Cyp18a1-RNAi prepupae. (A) A model for the regulation of βFTZ-F1 and the role of Cyp18a1 and 20E. The 20E peak at pupariation induces a set of genes including E75B, DHR3, Blimp-1 and Cyp18a1. Under these conditions, E75B represses DHR3, a transcriptional activator of βFTZ-F1, whereas Blimp-1 directly represses βFTZ-F1 expression. As Cyp18a1 lowers the 20E level, the expression of 20E-inducible genes E75B, DHR3 and Blimp-1 declines. Low expression of E75B and Blimp-1 at 6 hours APF allows residual DHR3 to induce βFTZ-F1. (B) The expression of 20E-regulated genes analyzed using quantitative RT-PCR during the prepupal-pupal transition. Data are expressed as fold changes relative to the lowest expression level for each gene, arbitrarily set to 1. (C) Expression of hsβFTZ-F1 rescues the leg phenotype (red arrows) of Cyp18a1-RNAi animals. A da>Cyp18a1-RNAi, hsβFTZ-F1 pharate adult with normally developed legs like the control (da>) is shown. (D) Ectopic expression of hsβFTZ-F1 recsues lethality and leg abnormalities of Cyp18a1-RNAi animals.