Detailed Analysis of Transcriptional Regulation by Activation Functions-1 and -2 of the Human Estrogen Receptor

The human estrogen receptor (ER), is a 66 kilodalton, ligand-inducible transcription factor that regulates the transcription of estrogen-responsive genes. Like other steroid hormone receptors, the ER is a modular protein that can be divided into separable domains with specific functions, such as ligand binding, dimerization, DNA binding, and transactivation. The ER contains two distinct activation domains that are involved in transcription activation. Activation function-1 (AF-1) is located in the amino-terminal A/B domain and activation function-2 (AF-2) is near the carboxyl-terminus in the E domain. In most cell and promoter contexts, AF-1 and AF-2 act synergistically to allow full transcriptional activity of ER. Our studies were designed to examine the transcriptional activity of ER and focus on both the amino- and carboxyl-terminal activation domains. We have demonstrated a functional interaction between the amino- and carboxyl-terminal regions of ER, that was promoted by both estradiol and antiestrogen binding. This interaction was transcriptionally productive, however, only in the presence of estradiol. In subsequent studies, we examined the ability of the steroid receptor coactivator-1 (SRC-1) protein to facilitate the integration of the amino- and carboxyl-terminal functions of ER. We have found that SRC-1, which has been shown to significantly increase ER transcriptional activity, enhanced the interaction, mediated by either estrogen or antiestrogen, between the amino- and carboxyl-terminal regions of ER. This enhanced interaction resulted in increased transcriptional activity only in the presence of estradiol. We also analyzed the A/B domain of ER and its role in the transcriptional activity of ER elicited by estrogens and antiestrogens. Studies showed that AF-1 contained a discrete region necessary for antiestrogen agonism that was not required for estradiol-stimulated activity. Also, we characterized V364E, a novel ER mutant containing a single amino acid substitution at residue 364 in the hormone binding domain, that is a transcriptionally active receptor variant, yet was able to significantly suppress wild type ER activity when both receptors were present together in cells. Together, these studies contribute toward elucidating the detailed biochemical mechanism of activated transcription by the ER.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Molecular and Integrative Physiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• McInerney, Eileen M.

Contributors dc:contributor

• Katzenellenbogen, Benita S.

• Biology, Molecular

Language dc:language

eng

Identifier

(MiAaPQ)AAI9737193

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87257