Coordination of Drosophila Metamorphosis by Two Ecdysone-Induced Nuclear Receptors

Abstract

The functions of the ecdysone-induced DHR3 and E75B orphan nuclear receptors in the early stages of Drosophila metamorphosis were investigated. DHR3 represses the ecdysone induction of early genes turned on by the pulse of ecdysone that triggers metamorphosis. It also induces betaFTZF1, an orphan nuclear receptor that is essential for the appropriate response to the subsequent prepupal pulse of ecdysone. The E75B receptor, which lacks a complete DNA binding domain, inhibits this inductive function by forming a complex with DHR3 on the betaFTZF1 promoter, thereby providing a timing mechanism for betaFTZF1 induction that is dependent on the disappearance of E75B.

Nuclear receptor BgFTZ‐F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insect Blattella germanica

“…1; Cruz et al, 2007). Given that DHR3 regulates the expression of ␤FTZ-F1 at the prepupal stage of D. melanogaster (White et al, 1997;Lam et al, 1999), we sought to determine whether BgHR3 was required for Bg-FTZ-F1 activation in B. germanica. In this line, we studied the BgFTZ-F1 mRNA levels in prothoracic glands and in abdominal segments with epi- Cruz et al (2003).…”

“…In D. melanogaster, the four nuclear receptors that we have characterized in B. germanica up to now, EcR, RXR, E75, and HR3, constitute a functional axis that controls the expression of the nuclear hormone receptor FTZ-F1 in a very precise way (White et al, 1997;Lam et al, 1999). Therefore, the obvious next step to further study the role of 20E in the development of B. germanica has been the characterization of the ortholog of FTZ-F1 in this species.…”

Nitric oxide directly regulates gene expression during Drosophila development: need some gas to drive into metamorphosis?: Figure 1.

“…On the other hand, expression of bFTZ-F1 is repressed when the 20E titer is high and is only induced after the hemolymph 20E titer declines (Woodard et al 1994;Broadus et al 1999;Yamada et al 2000;Rewitz et al 2010). This unique expression profile of bFTZ-F1 is usually explained by the balance between DHR3 accumulation and E75 decay (White et al 1997). When the 20E titer is high, one of the E75 isoforms, E75B, suppresses DHR3 activity to induce bFTZ-F1.…”

Thehedgehog-related genequa-1 is required for molting inCaenorhabditis elegans

“…This critical developmental transition is accompanied by characteristic morphological changes. In Drosophila, molting is regulated by pulses of steroid hormone, 20-hydroxyecdysone, and the regulatory cascade involves the ecdysone receptor (EcR), which is a transcription factor of the nuclear hormone receptor group, and two other nuclear hormone receptors (NHRs), DHR3 and ␤FTZ-F1 (Kageyama et al, 1997;Lam et al, 1997Lam et al, , 1999White et al, 1997).…”