Reconstruction of ligand- dependent transactivation of Choristoneura fumiferana ecdysone receptor in yeast

Hiep T. Tran, Hossein B. Askari, Salam Shaaban, Laura Price, Subba R. Palli, Tarlochan S. Dhadialla, Glenn R. Carlson, Tauseef R. Butt

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Ecdysteroids play an important role in regulating development and reproduction in insects. Interaction of 20-hydroxyecdysone (20E) with ecdysone receptor (EcR) as a heterodimer with ultraspiracle (USP) protein triggers the activation of 20E-responsive genes. In this paper we describe a ligand-mediated transactivation system in yeast using the spruce budworm Choristoneura fumiferana ecdysone receptor (CfEcR). Coexpression of C. fumiferana USP (CfUSP) with CfEcR in yeast led to constitutive transcription of the reporter gene. However, deletion of the A/B domain of CfUSP abolished constitutive activity observed for the CfUSP:CfEcR complex. Replacement of USP with its mammalian homolog retinoid X receptors (RXRs) abolished the constitutive activity of the heterodimer but it did not restore EcR ligand-mediated transactivation. These data suggest that USP and its A/B domain play a role in the constitutive function of CfEcR:USP in yeast. A ligand-mediated transactivation was observed when GRIP1, a mouse coactivator gene, was added to EcR:RXR or EcR:Δ/BUSP complexes. Deletion of the A/B domain of EcR in the context of ΔA/BEcR:RXR:GRIP1 or ΔA/BEcR:ΔA/BUSP:GRIP1 dramatically improved the ligand-dependent transactivation. This is the first example of highly efficient ligand-dependent transactivation of insect EcR in yeast. Analysis of transactivation activity of different ecdysteroidal compounds showed that the yeast system remarkably mimics the response observed in insect tissue culture cells and whole insect systems. The results open the way to develop assays that can be used to screen novel species-specific ecdysone agonist/antagonist insecticides.

Original languageEnglish
Pages (from-to)1140-1153
Number of pages14
JournalMolecular Endocrinology
Issue number7
StatePublished - 2001

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology


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