Ecdysteroid hormone action

Abstract

Several reviews devoted to various aspects of ecdysone research have been published during the last few years. Therefore, this article concentrates mainly on the considerable progress in ecdysone research observed recently, and will cover the results obtained during the last 2 years. The main emphasis is put on the molecular mode of ecdysteroid receptor-mediated hormone action. Two examples of interaction with other hormonal signalling pathways are described, namely crosstalk with juvenile hormone and insulin. Some selected, recently investigated examples of the multitude of hormonal responses are described. Finally, ecological aspects and some practical applications are discussed.

Fig. 1

Transcriptional activity of EcR/Usp in CHO-K1 cells. Heterodimers of EcR isoforms with wild-type and mutated Usps are compared. L259 is located in the loop between helix 1 and helix 3. This amino acid is involved in fixation of helix 12 in the antagonistic position according to Clayton et al. [40]

Fig. 2

Transcriptional activity of EcR isoforms partnered with wild-type Usp. a CHO-K1 cells. b Insect (S2, Drosophila) cells. Transcriptional activity was determined by a luciferase reporter and normalised on EcR concentration as described in Ruff et al. [26]. White bars without hormone, black bars with 1μM muristerone A

Fig. 3

Basal transcriptional activity of EcR^K497E isoforms in the absence of Usp in CHO-K1 cells. Transcriptional activity was determined by a luciferase reporter and normalised on EcR concentration as described in [26]. White bars without hormone, black bars with 1μM muristerone A

Fig. 4

Scheme of Toll signalling pathways involved in regulation of insect development and innate immunity in insects and vertebrates (modified according to Kimbrell and Beutler [146]). Dif Dorsal-related immunity factor, Imd immune deficiency, TLR4 Toll-like receptor 4, IRAK interleukin-1 receptor-associated kinase, homologue to Drosophila Pelle, IκB inhibitor of κB, IKK IκB kinase