Human estrogen receptor transactivational capacity is determined by both cellular and promoter context and mediated by two functionally distinct intramolecular regions

Published

Journal Article

We have used a series of human estrogen receptor (ER) mutants to evaluate the cell- and promoter-specific transcriptional activities of the TAF1 and TAF2 transactivation regions within the human ER. We show that the manifestation of TAF1 or TAF2 function depends strongly upon promoter context; on certain promoters, both the TAF1 and TAF2 activators are required for wild-type transcriptional activity, whereas on other promoters, the TAF1 and TAF2 activators function independently. Using these constructs, we show that the antagonist activity of the triphenylethylene-derived antiestrogens, e.g. tamoxifen, arises from their intrinsic inability to activate ER TAF2 function. However, on certain promoters, these antiestrogens efficiently activate gene transcription through ER. Consistent with this observation, the TAF2 function of the ER is not required on all promoters. In these TAF2- independent promoter contexts, TAF2 function may be provided by a separate transcription factor bound to the promoter. These data suggest that 1) TAF1 may be the major transcriptional activator of the ER; and 2) TAF2 functions as a transcriptional facilitator. On promoters where TAF2 function is provided independently of the ER, the TAF1 function of the ER can function independently of TAF2 activity, allowing triphenylethylene-derived antiestrogens to demonstrate partial agonist activity. These observations provide a possible molecular explanation for the tissue-specific partial agonist properties of tamoxifen and related triphenylethylene antiestrogens observed in vivo.

Full Text

Duke Authors

Cited Authors

  • Tzukerman, MT; Esty, A; Santiso-Mere, D; Danielian, P; Parker, MG; Stein, RB; Pike, JW; McDonnell, DP

Published Date

  • January 1, 1994

Published In

Volume / Issue

  • 8 / 1

Start / End Page

  • 21 - 30

International Standard Serial Number (ISSN)

  • 0888-8809

Digital Object Identifier (DOI)

  • 10.1210/me.8.1.21

Citation Source

  • Scopus