Characterization of the amino-terminal transcriptional activation function of the human estrogen receptor in animal and yeast cells.
We have previously reported that the transcriptional activation function AF-1, located in the A/B region of the human estrogen receptor, exhibits cell-type and promoter context specificity in both animal cells and yeast. To further characterize AF-1, we have constructed a number of deletion mutants spanning the A/B region in the context of either the whole human estrogen receptor or the A/B region linked to the GAL4 DNA binding domain, and tested their transcriptional activity in chicken embryo fibroblasts and in yeast cells, two cell types in which AF-1 efficiently activates transcription on its own. Additionally, we utilized HeLa cells in which AF-1 is poorly active but can synergize with the transcriptional activation function AF-2 located in the hormone binding domain. We show that in animal cells the "independent" activity of AF-1 is embodied in a rather hydrophobic proline-rich 99-amino acid activating domain (amino acids 51-149), whereas amino acids 51-93 and 102-149 can independently synergize with AF-2. Interestingly, in yeast, three discrete activating domains (amino acids 1-62, 80-113, and 118-149) are almost as active on their own as the whole A/B region, indicating that multiple activating domains can operate independently in yeast. Our study also demonstrates that, within the context of the whole human estrogen receptor, the same AF-1 activating domains are "induced" by either estradiol or 4-hydroxytamoxifen.
Metzger
D
D
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Collège de France, Illkirch, C.U. de Strasbourg.
Ali
S
S
Bornert
J M
JM
Chambon
P
P
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D004958:Estradiol / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011960:Receptors, Estrogen / Q000737:chemistry / Q000502:physiology*; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D015533:Transcriptional Activation; D015003:Yeasts
D011960:Receptors, Estrogen; D013629:Tamoxifen; C016601:afimoxifene; D004958:Estradiol