The Presence of Both the Amino- and Carboxyl-Terminal Domains in the AR Is Essential for the Completion of a Transcriptionally Active Form with Coactivators and Intranuclear Compartmentalization Common to the Steroid Hormone Receptors: A Three-Dimensional Imaging Study

Information on the regulation of steroid hormone receptors and their distinct functions within the human endometrial epithelium is largely unavailable. We have immortalized human primary endometrial epithelial cells (EECs) isolated from a normal proliferative phase endometrium by stably transfecting the catalytic subunit (hTERT) of the human telomerase complex and cultured these hTERT-EECs now for over 350 population doublings. Active hTERT was detected in hTERT-EECs employing the telomerase repeat amplification assay protocol. hTERT-EECs revealed a polarized, non-invasive epithelial phenotype with apical microvilli and production of a basal lamina when grown on a three-dimensional collagen–fibroblast lattice. Employing atomic force microscopy, living hTERT-EECs were shown to produce extracellular matrix (ECM) components and ECM secretion was modified by estrogen and progesterone (P4). hTERT-EECs expressed inducible and functional endogenous estrogen receptor-alpha (ER-alpha) as demonstrated by estrogen response element reporter assays and induction of P4 receptor (PR). P4 treatment down-regulated PR expression, induced MUC-1 gene activity and resulted in increased ER-beta transcriptional activity. Gene activities of cytokines and their receptors interleukin (IL)-6, leukemia inhibitory factor (LIF), IL-11 and IL-6 receptor (IL6-R), LIF receptor and gp130 relevant to implantation revealed a 17 beta-estradiol (E2)-mediated up-regulation of IL-6 and an E2- and P4-mediated up-regulation of IL6-R in hTERT-EECs. Thus, hTERT-EECs may be regarded as a novel in vitro model to investigate the role of human EECs in steroid hormone-dependent normal physiology and pathologies, including implantation failure, endometriosis and endometrial cancer.

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Molecular Biology of the Androgen Receptor

Journal of Clinical Oncology ◽

10.1200/jco.2002.10.018 ◽

2002 ◽

Vol 20 (13) ◽

pp. 3001-3015 ◽

Cited By ~ 580

Author(s):

Edward P. Gelmann

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Ligand Binding ◽

Dna Sequences ◽

Hormone Receptors ◽

Steroid Hormone ◽

Three Dimensional ◽

Intramolecular Interactions ◽

Steroid Hormone Receptors ◽

Dimensional Structure

ABSTRACT: Androgen receptor (AR) is a member of the steroid hormone receptor family of molecules. AR primarily is responsible for mediating the physiologic effects of androgens by binding to specific DNA sequences that influence transcription of androgen-responsive genes. The three-dimensional structure of the AR ligand-binding domain has shown it is similar to other steroid hormone receptors and that ligand binding alters the protein conformation to allow binding of coactivator molecules that amplify the hormone signal and mediate transcriptional initiation. However, AR also undergoes intramolecular interactions that regulate its interactions with coactivators and influence its activity. A large number of naturally occurring mutations of the human AR gene have provided important information about AR molecular structure and intermolecular interactions. AR is also a critical mediator of prostate cancer promotion, conferring growth signals to prostate cancer cells throughout the natural history of the disease. Late-stage prostate cancer, unresponsive to hormonal deprivation, sustains AR signaling through a diverse array of molecular strategies. Variations in the AR gene may also confer genetic predisposition to prostate cancer development and severity. Further understanding of AR action and new strategies to interfere with AR signaling hold promise for improving prostate cancer therapy.

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The 90 kDa heat-shock protein (hsp90) modulates the binding of the oestrogen receptor to its cognate DNA

Biochemical Journal ◽

10.1042/bj3140205 ◽

1996 ◽

Vol 314 (1) ◽

pp. 205-213 ◽

Cited By ~ 45

Author(s):

Michèle SABBAH ◽

Christine RADANYI ◽

Gérard REDEUILH ◽

Etienne-Emile BAULIEU

Keyword(s):

Heat Shock ◽

Heat Shock Protein ◽

Oestrogen Receptor ◽

Hormone Receptors ◽

Elevated Temperatures ◽

Specific Binding ◽

Steroid Hormone ◽

Active Form ◽

Steroid Hormone Receptors ◽

High Affinity

The role of heat-shock protein 90 (hsp90) in the regulation of the oestrogen receptor (ER) function is less well understood than for other steroid-hormone receptors because hsp90 is not involved in the stabilization or induction of a high-affinity ligand-binding state of ER nor in the inhibition of receptor dimerization. Electrophoretic mobility-shift assays, using purified ER and hsp90, were employed to investigate directly the effect of hsp90 on the ability of ER to bind to the oestrogen-response element (ERE) from the vitellogenin A2 gene. Contrary to models in which hsp90 binds to and passively inactivates steroid-hormone receptors, our studies show that the binding of ER to ERE is inversely dependent on the relative concentration of hsp90. Exposure of purified ER–hsp90 complexes to ERE led to the dissociation of hsp90 and concomitant specific binding of ER to ERE. We demonstrate that the amount of ER–ERE complex decreased with increasing concentrations of hsp90. Furthermore hsp90 dissociated preformed high-affinity ER–ERE complexes. Kinetic dissociation experiments indicate that hsp90 acts in a dynamic and specific process rather than by simple trapping of ER owing to its inherent off-rate. The receptor released from the ERE-bound state by hsp90 was recovered associated with hsp90 and was able to rebind to ERE. These results indicate that hsp90 does not suppress ER function merely by steric hindrance. On the basis of these results and others, we propose that, in vivo, hsp90 may play a dual role in ER function: (i) at a physiological temperature, hsp90 stabilizes an active form of the receptor in accordance with its general molecular chaperone role; (ii) at elevated temperatures or under other environmental stress, the increased cellular concentration of hsp90 negatively interferes with ER-dependent transcription, in accordance with the inhibition of gene transcription attributed to hsp90 after heat shock.

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