Requirement of co-factors for the ligand-mediated activity of the insect ecdysteroid receptor in yeast
Bibliographic record
Abstract
In insects, a steroid hormone 20-hydroxyecdysone has an important role in regulating critical events such as development and reproduction. The action of 20-hydroxyecdysone is mediated by its binding to the ecdysteroid receptor (EcR), which requires a heterodimeric partner, ultraspiracle protein (USP), a homologue of the retinoid X receptor (RXR). The EcR-USP heterodimer represents a functional receptor complex capable of initiating transcription of early genes. Our goal was to establish a ligand-dependent transactivation system in yeast utilizing an insect EcR-USP heterodimer. This has been achieved using mosquito Aedes aegypti AaEcR-USP. Expression of AaEcR alone, but not USP, resulted in constitutive transcription of the ecdysone reporter gene coupled with the Drosophila heat shock protein-27 ecdysone response elements. Removal of the N-terminal A/B domain of AaEcR abolished its constitutive transcription. Constitutive transcription was also eliminated in the presence of its heterodimeric partner, AaUSPa, AaUSPb or mammalian RXR. This suggests that the A/B domain is essential for the EcR ligand-independent transactivation and its interaction with the yeast transcription complex. A ligand-mediated transactivation of Aa(Delta A/B)EcR-USP or Aa(Delta A/B)EcR-RXR heterodimers in response to an ecdysteroid agonist RH-5992 was observed only in the presence of GRIP1, a mouse co-activator. In the presence of a co-repressor, SMRT, Aa(Delta A/B)EcR-USP heterodimer exhibited a ligand-dependent repression activity. In addition, ligand-dependent transactivation systems for spruce budworm and fruit fly ecdysone receptors were also reported. This is the first report establishing the requirements of co-factors for a highly efficient ligand-dependent function of the insect EcR-USP in yeast. These findings open a way to study insect EcR-USP structure and function and to identify ligands that are specific for a certain group of insects, such as mosquitoes.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".