文章基本信息

标题：Modulation of Coactivator Recruitment by Cooperative Ligand Binding to Human Estrogen Receptor α and β
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作者：Sachiko Suzuki ; Satoshi Nishida ; Ken-ichi Ohno 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2007
卷号：30
期号：9
页码：1641-1647
DOI：10.1248/bpb.30.1641
出版社：The Pharmaceutical Society of Japan
摘要：Estrogen receptor (ER) is a member of the nuclear receptor superfamily, and functions as a ligand-dependent transcription factor with roles in cell growth and differentiation. In addition to endogenous estrogen, 17β-estradiol (E₂) and artificial antagonists, many suspected environmental estrogenic chemicals are reported to bind to ER, with various affinities and transcriptional responses. ER is also an allosteric protein and shows a positive cooperative interaction with E₂. Cooperativity affects inter-subunit interaction, and while ligand-bound ER interacts with coactivators, antagonist-bound ER does not. We therefore hypothesized that ligand-binding characteristics influence coactivator recruitment to the ER dimer, and thereby affect transcriptional activity. We investigated the interaction between ER and human Steroid Receptor Coactivator-1 (SRC-1), in the presence of compounds exhibiting various Hill coefficients. In the case of both ER subtypes (ERα and ERβ), the Hill coefficients of the compounds tested correlated with the affinity of the ER-ligand complex to SRC-1, with the exception of ERβ-4- n -nonylphenol and ER-antagonist complexes. This is the first report to investigate the relationship between Hill coefficients of ligand binding and coactivator interaction with the ER-ligand complex. We also examined the proteolytic digestion of ER using trypsin, in the presence and absence of compounds with various Hill coefficients, to investigate ligand-dependent conformational changes in ER. We used not only agonists and antagonists but also compounds of weak biological activity (partial agonists). Our results shed light on the subtle modulation of transcriptional activation by chemical agents.
关键词：estrogen receptor;fluorescence polarization;Hill coefficient;limited protease digestion;steroid receptor coactivator-1