Interaction of Androgen Receptors with Androgen Response Element in Intact Cells
ROLES OF AMINO- AND CARBOXYL-TERMINAL REGIONS AND THE LIGAND*
- From the ‡Institute of Biomedicine, Department of Physiology, and the §Department of Clinical Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland
Abstract
Promoter interference assay was employed to examine in intact cells the roles of the functional domains of androgen receptor (AR) and the ligand for specific DNA interactions using a cytomegalovirus-(androgen response element)-chloramphenicol acetyltransferase reporter (pCMV-ARE2-CAT). Native rat and human ARs interfered with pCMV-ARE2-CAT expression in a hormone-dependent fashion. Low steroid-independent interference seemed to occur because of the ligand binding domain (LBD), which was transcriptionally inhibitory also in a heterologous context. AR devoid of LBD (rARΔ641–902) decreased pCMV-ARE2-CAT activity by 50%. The rARΔ46–408 mutant devoid of the NH2-terminal transcription activation region exhibited ligand-dependent promoter interference of a similar magnitude. Ligand and DNA binding-deficient mutants (hARM807R and rARC562G, respectively) did not influence pCMV-ARE2-CAT expression, although hARM807R binds to ARE in vitro. Non-steroidal anti-androgens casodex and hydroxyflutamide antagonized agonist-dependent promoter interference, whereas cyproterone acetate, RU 56187, RU 57073, and RU 59063 were partial agonists/antagonists. Collectively, interaction of ARs with ARE in intact cells does not require the presence of the COOH-terminal or NH2-terminal domain and/or their interaction. In the context of native AR, however, the androgen-induced conformational change in LBD is mandatory for generation of a transcriptionally competent receptor that binds to DNA in intact cells.
Footnotes
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↵* This work was supported by grants from the Medical Research Council (Academy of Finland), the Finnish Foundation for Cancer Research, the Jalmari and Rauha Ahokas Foundation, and the University of Helsinki.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed: Institute of Biomedicine, Dept. of Physiology, University of Helsinki, P.O. Box 9 (Siltavuorenpenger 20 J), FIN-00014 Helsinki, Finland. Tel.: 358-9-191-8542; Fax: 358-9-191-8681; E-mail:jorma.palvimo{at}helsinki.fi.
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↵1 The abbreviations used are: AR, androgen receptor; hAR, human AR; rAR, rat AR; ARE, androgen response element; CAT, chloramphenicol acetyltransferase; CMV, cytomegalovirus; DBD, DNA binding domain; ER, estrogen receptor; ERE, estrogen response element; LBD, ligand-binding domain; MMTV, mouse mammary tumor virus; Nterm, NH2-terminal region of rAR; PR, progesterone receptor; PRE, progesterone response element; SV, simian virus.
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↵2 T. Ikonen, J. J. Palvimo, and O. A. Jänne, submitted for publication.
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↵3 U. Karvonen, O. A. Jänne, and J. J. Palvimo, unpublished observations.
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- Received November 15, 1996.
- Revision received April 17, 1997.
