Ecdysteroid Receptors and their Applications in Agriculture and Medicine

Distinct roles of Broad isoforms in regulation of the 20-hydroxyecdysone effector gene, Vitellogenin, in the mosquito Aedes aegypti

“…The receptor complex acts as a transcription factor recognizing specific DNA sequences (ecdysone response elements) of their target promoters. Binding of 20E and agonist ligands to EcR/USP triggers a conformational change that attracts transcriptional coactivators, leading to transcriptional activation of the target genes (Palli et al, 2005). In response to the 20E titers during Drosophila metamorphosis, EcR/USP directly activates a group of primary-response target genes, including a small set of so-called early genes, such as E74, E75 and Broad (br), which encode intermediate transcriptional regulators (Thummel, 2001).…”

The variety of complexes formed by EcR and Usp nuclear receptors in the nuclei of living cells

“…Although components of the EcR/Usp complex are active in mammalian cells and are thus potentially useful in the regulation of transgene expression in mammalian cells and transgenic animals (Lafont and Dinan, 2003;Palli et al, 2005), there is still little data concerning the molecular mechanisms governing the subcellular distribution of the complex and its components. Therefore, earlier we had analyzed the subcellular trafficking of the EcRB1 isoform and Usp in mammalian cells (CHO-K1, COS-7 and HeLa) which are routinely used for EcR/Usp heterologous studies (Gwozdz et al, 2007;Nieva et al, 2005).…”

“…3 20.9±2.3% of cells exhibited fluorescence after the coexpression of YN-EcR and YC-Usp. This value did not significantly change (to the value of 23.4±1.45%) when Muristerone A, the ligand which has been widely used for induction of ecdysteroid receptordependent transcription in mammalian cells (Lafont and Dinan, 2003;Palli et al, 2005), was added (Fig. 3).…”

“…Interestingly, the presence of Muristerone A, the ligand which has been widely used for the induction of ecdysteroid-dependent transcription in mammalian cells (Palli et al, 2005), does not significantly change the amount of EcR/Usp and EcR/EcR complexes and it does not influence their subcellular localization.…”

“…Since a variety of studies have demonstrated that EcR and Usp can function not only in insects but also in mammalian cell lines, the constituents of the EcR/Usp complex, and especially EcR, are of great interest as a source for creating artificial molecular switches (Lafont and Dinan, 2003;Palli et al, 2005). The main advantage of 20E receptor-based molecular switches in mammalian systems is that ecdysteroids, which are used to induce a switch, are structurally different from mammalian steroids, and they do not bind to vertebrate steroid receptors (Lafont and Dinan, 2003).…”