Inhibition of estrogen-responsive gene activation by the retinoid X receptor beta: evidence for multiple inhibitory pathways.

Détails

ID Serval
serval:BIB_9448D75F5AB7
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Inhibition of estrogen-responsive gene activation by the retinoid X receptor beta: evidence for multiple inhibitory pathways.
Périodique
Molecular and Cellular Biology
Auteur(s)
Segars J.H., Marks M.S., Hirschfeld S., Driggers P.H., Martinez E., Grippo J.F., Brown M., Wahli W., Ozato K.
ISSN
0270-7306[print], 0270-7306[linking]
Statut éditorial
Publié
Date de publication
04/1993
Volume
13
Numéro
4
Pages
2258-2268
Langue
anglais
Notes
Publication types: In Vitro ; Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S.
Publication Status: ppublish
Résumé
The retinoid X receptor beta (RXR beta; H-2RIIBP) forms heterodimers with various nuclear hormone receptors and binds multiple hormone response elements, including the estrogen response element (ERE). In this report, we show that endogenous RXR beta contributes to ERE binding activity in nuclear extracts of the human breast cancer cell line MCF-7. To define a possible regulatory role of RXR beta regarding estrogen-responsive transcription in breast cancer cells, RXR beta and a reporter gene driven by the vitellogenin A2 ERE were transfected into estrogen-treated MCF-7 cells. RXR beta inhibited ERE-driven reporter activity in a dose-dependent and element-specific fashion. This inhibition occurred in the absence of the RXR ligand 9-cis retinoic acid. The RXR beta-induced inhibition was specific for estrogen receptor (ER)-mediated ERE activation because inhibition was observed in ER-negative MDA-MB-231 cells only following transfection of the estrogen-activated ER. No inhibition of the basal reporter activity was observed. The inhibition was not caused by simple competition of RXR beta with the ER for ERE binding, since deletion mutants retaining DNA binding activity but lacking the N-terminal or C-terminal domain failed to inhibit reporter activity. In addition, cross-linking studies indicated the presence of an auxiliary nuclear factor present in MCF-7 cells that contributed to RXR beta binding of the ERE. Studies using known heterodimerization partners of RXR beta confirmed that RXR beta/triiodothyronine receptor alpha heterodimers avidly bind the ERE but revealed the existence of another triiodothyronine-independent pathway of ERE inhibition. These results indicate that estrogen-responsive genes may be negatively regulated by RXR beta through two distinct pathways.
Mots-clé
Base Sequence, Binding Sites, DNA Mutational Analysis, DNA-Binding Proteins/genetics, Estrogens/pharmacology, Gene Expression Regulation/drug effects, Humans, Macromolecular Substances, Molecular Sequence Data, Nuclear Proteins/genetics, Oligodeoxyribonucleotides/chemistry, Promoter Regions, Genetic, RNA, Messenger/genetics, Receptors, Cell Surface/genetics, Receptors, Estrogen/physiology, Receptors, Retinoic Acid, Receptors, Thyroid Hormone/genetics, Regulatory Sequences, Nucleic Acid, Retinoid X Receptors, Sequence Deletion, Structure-Activity Relationship, Transcription Factors/genetics, Transcriptional Activation, Tumor Cells, Cultured
Pubmed
Création de la notice
24/01/2008 17:05
Dernière modification de la notice
03/03/2018 19:37
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