Horm Metab Res 2002; 34(8): 425-430
DOI: 10.1055/s-2002-33599
Original Basic

© Georg Thieme Verlag Stuttgart · New York

Transcriptional Suppression of the Estrogen Receptor by Truncated Estrogen Receptor-Alpha

M.  Ikeda 1 , M.  Okai 2 , T.  Miyoshi 2 , S.  Tone 1 , Y.  Minatogawa 1
  • 1Department of Biochemistry, Kawasaki Medical School, Okayama, Japan
  • 2Department of Clinical Engineering, Kawasaki College of Allied Health Professions, Okayama, Japan
Further Information

Publication History

Received: 2 January 2002

Accepted after revision: 14 May 2002

Publication Date:
25 September 2002 (online)

Abstract

The estrogen receptor (ER) is composed of six major functional domains - the A/B domain as the activation function 1 domain, domain C as the DNA-binding domain, domain D as a hinge domain, and domain E/F as the ligand-dependent transcriptional domains. A novel protein (designated as SRB-RGS) that interacted with domains C and D of ERα (ERα C/D) repressed the transcriptional activity of ERα. In this study, we have examined whether ERα C/D releases transcriptional suppression of ERα by intrinsic SRB-RGS. The expression vector of ERα C/D was transfected to the human cancer cell, KPL-1, which expressed the intrinsic ER. Unexpectedly, transcriptional suppression of ER by ERα C/D was observed. COS-7 cells, which have no intrinsic ER, showed a similar suppression of ERα by co-transfection of ERα and ERα C/D. The DNA-binding and the estrogen-binding activities of ERα decreased on co-transfection of ERα C/D, suggesting a decrease in the receptor protein itself. It is likely that the degradation of ER by co-transfection caused the transcriptional suppression of the ER.

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Dr. M. Ikeda

Department of Biochemistry · Kawasaki Medical School ·

577 Matsushima · Kurashiki · Okayama 701-0192 · Japan ·

Phone: + 81 (86) 462 1111 ·

Fax: + 81 (86) 462 1199

Email: ikeda@bcc.kawasaki-m.ac.jp