Ecdysone-responsive Genes Research Articles

Regulatory and developmental aspects of ecdysone-regulated gene expression

Summary The IXth Ecdysone Workshop marked a turning point in studies of ecdysone and gene regulation, as there has been significant progress in our understanding both of the regulatio9n and function of ecdysone-inducible genes. A number of reports confirmed the existence of molecules bearing structural similarities to vertebrate hormone receptors and regulatory sequences resembling their response elements. Work in progress shows that certain early ecdysone responsive genes may encode transcription factors that interact so as to control subsequent stage and tissue patterns of hormonal response.

Characterization of IMP‐E3, A gene active during imaginal disc morphogenesis in Drosophila melanogaster

The steroid hormone 20-hydroxyecdysone (20-HE) induces imaginal discs to form adult appendages in Drosophila. We have isolated a set of six ecdysone-responsive genes that apparently encode disc cell-surface or secreted proteins. Transcripts from one of these genes, IMP-E3, accumulate rapidly within 1-2 h in response to hormone. Developmentally, IMP-E3 transcripts reach maximum levels during the first stages of metamorphosis (white prepupae, WPP) and are primarily limited to imaginal tissues. Transcripts are also present during embryogenesis (0-3 h and 12-18 h). Two different-sized transcripts (1.2 and 1.4 kb) result from differential polyadenylation, with the larger transcript predominating in WPP. The conceptual IMP-E3 protein contains a signal peptide, an RGD sequence, and a potential glycosylphosphatidylinositol anchor. We speculate that the protein provides a transient cue important for imaginal disc morphogenesis.