Ecdysteroid Regulation and DNA Binding Properties of Drosophila Nuclear Hormone Receptor Superfamily Members

摘要: Pulses of the steroid hormone 20-hydroxyecdysone (20E) trigger larval-to-adult metamorphosis Drosophila by reprogramming gene expression throughout organism. 20E directly induces a small set early regulatory genes that repress their own and induce large late secondary-response genes. We show here two members nuclear receptor superfamily, DHR3 DHR39, are rapidly induced 20E, in parallel with Both also require protein synthesis at high concentrations for maximal induction hormone. Developmental Northern blot analysis reveals DHR39 is mid third instar larvae expressed most larval prepupal development, while briefly prepupae. The 20E-induction temporal patterns transcription strongly suggest these function together to coordinate complex networks direct stages metamorphosis. In an initial effort understand how orphan receptors might during we examined DNA binding properties compared them known superfamily involved ecdysteroid response: EcR, Usp, E75A, E78A, beta FTZ-F1. Upon testing all pairwise combinations seven proteins on panel oligonucleotides, only EcR Usp bound as heterodimer, indicating this interaction highly specific. With exception which did not bind any sequence tested, each remaining able single consensus AGGTCA half-site; however, displayed different specificities depending flanking nucleotide sequence. These observations 20E-regulated monomers control target