Ligand binding is without effect on complex formation of the ligand binding domain of the ecdysone receptor (EcR)

Greb‐Markiewicz, Beata; Fauth, Torsten; Spindler-Barth, Margarethe

doi:10.1002/arch.20054

Cited by 4 publications

(2 citation statements)

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“…Although both receptors can enter the nuclei independently, the heterodimerization partners mutually enhance nuclear localization. This is most In the absence of DNA, dimerization of nuclear receptors in cytoplasm is mediated by the ligandbinding domains, which apparently occurs already in the absence of hormone to a sufficient degree, although ligand binding increases dimerization of LBDs of EcR and Usp significantly (Grebe et al, 2003;Greb-Markiewicz et al, 2005).…”

Section: Nuclear Localization Of Ecr and Uspmentioning

confidence: 99%

Nuclear localization and DNA binding of ecdysone receptor and ultraspiracle

Cronauer¹,

Braun²,

Tremmel³

et al. 2007

Arch Insect Biochem Physiol

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The Ecdysone receptor (EcR) is distributed between cytoplasm and nucleus in CHO cells. Nuclear localization is increased by the ligand Muristerone A. The most important heterodimerization partner Ultraspiracle (Usp) is localized predominantly in the nucleus. We used the diethylentriamine nitric oxide adduct DETA/NO, which releases NO and destroys the zinc-finger structure of nuclear receptors, to investigate whether nuclear EcR and Usp interact with DNA. If expressed separately, Usp and EcR in the absence of hormone do not interact with DNA. The hormone-induced increase in nuclear EcR is due to enhanced DNA binding. In the presence of Usp, EcR is shifted nearly quantitatively into the nucleus. Only a fraction (approximately 30%) of the heterodimer is sensitive to DETA/NO. Interaction of the heterodimer with DNA is mediated mainly by the C-domain of EcR. Deletion of the DNA-binding domain of Usp only slightly reduces nuclear localization of EcR/Usp, although the nuclear localization signal of Usp is not present anymore. The results indicate that EcR and Usp can enter the nucleus independently, but cotransport of both receptors mediated by dimerization via the ligand binding domains is possible even in the absence of hormone.

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Section: Nuclear Localization Of Ecr and Uspmentioning

confidence: 99%

Nuclear localization and DNA binding of ecdysone receptor and ultraspiracle

Cronauer¹,

Braun²,

Tremmel³

et al. 2007

Arch Insect Biochem Physiol

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“…As previously demonstrated, several ecdysone receptor complexes of various molecular sizes that considerably exceed the molecular weight of the heterodimer are present in cytoplasms and nuclei (Greb-Markiewicz et al, 2005;Rauch et al, 1998). The exact composition of these complexes is unknown, but binding of comodulators certainly takes place, and is known to involve binding to the AB-domain.…”

Section: Different Receptor Complexes Interacting With Dna Can Be Dismentioning

confidence: 85%

DNA‐binding properties of Drosophila ecdysone receptor isoforms and their modification by the heterodimerization partner ultraspiracle

Braun

Azoitei

Spindler-Barth

2009

Arch Insect Biochem Physiol

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Transcriptional activity of ecdysone receptor (EcR) isoforms varies considerably and is modified further by the heterodimerization partner and hormone treatment. To investigate whether differences in DNA binding of receptor complexes are responsible for these variations in transcriptional activity, interaction of Drosophila EcR isoforms, and variants of Ultraspiracle (Usp), the orthologue of RXR, with the ecdysone response elements (EcRE) hsp 27, PAL-1, and DR-1, were determined by electrophoretic mobility shift assays. Receptor proteins were expressed in vertebrate cells (CHO-K1) in order to rule out an influence of endogenous receptor proteins. In the absence of a heterodimerization partner, weak DNA binding of EcR was detected even without hormone with EcR-A and -B1, but not EcR-B2. In the presence of hormone, all three isoforms show increased binding to the hsp 27 EcRE. The heterodimerization partner Usp increased DNA binding considerably. The hormone effect of heterodimers is more pronounced with both EcR-B isoforms compared to EcR-A. Two specific bands were obtained for EcR-A and B1 but only one band is visible with EcR-B2. Deletion of the C-domain of Usp still allows basal DNA binding of the heterodimer, but in contrast to full-length Usp, addition of hormone decreases the intensity of the retarded receptor band of all EcR isoforms and the EcREs hsp27 and DR-1 considerably, whereas interaction with the EcRE PAL-1 is only slightly affected. Synergistic effects on transcriptional activity are associated with the formation of different receptor DNA-complexes observed with 1xhsp27 and 3xhsp27. Comparison of DNA-binding properties of EcR isoforms and EcR/Usp heterodimers revealed that binding of receptor complexes to hsp 27 EcRE is dependent on the AB domain of EcR and the AB-, C-, and D-domains of the heterodimerization partner. Interaction with the hsp 27 EcRE correlates neither with ligand binding nor with transcriptional activity of the various receptor complexes. We, therefore, conclude that the different receptor functions are regulated separately, for example, by interaction with co-modulators or post-transcriptional modifications.

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