Properties of Overlapping EREs:  Synergistic Activation of Transcription and Cooperative Binding of ER

• Published in: Biochemistry (Easton) 1998-04, Vol.37 (17), p.6023-6032
• Main Authors: Massaad, Charbel, Coumoul, Xavier, Sabbah, Michèle, Garlatti, Michèle, Redeuilh, Gérard, Barouki, Robert
• Format: Article
• Language: English
• Subjects: Base Sequence; Breast Neoplasms; Carcinoma, Hepatocellular; Chlordan - pharmacology; Dimerization; Drug Synergism; Electrophoresis, Polyacrylamide Gel; Estrogen Antagonists - pharmacology; Estrogens - agonists; Estrogens - pharmacology; Gammaretrovirus - genetics; Genes, Overlapping - drug effects; Genes, Overlapping - physiology; Genetic Vectors - pharmacology; Humans; Molecular Sequence Data; Phenolsulfonphthalein - pharmacology; Protein Binding - drug effects; Protein Binding - genetics; Protein Structure, Tertiary; Receptors, Estrogen - chemistry; Receptors, Estrogen - genetics; Receptors, Estrogen - metabolism; Regulatory Sequences, Nucleic Acid - physiology; Transcription, Genetic - drug effects; Tumor Cells, Cultured; Xenobiotics - pharmacology
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi972445e

We have designed a novel estrogen-responsive unit, overERE, which consists of two overlapping ERE separated by 5 bp (center-to-center). In gel retardation assays, this sequence forms a low-mobility complex that migrates like an estrogen receptor tetramer. The receptor−overERE complex was specific and was supershifted by anti-ER H222 antibodies. Dose response studies showed that the formation of the receptor tetramer−overERE complex was cooperative. Truncated receptors were used to assess the contribution of the receptor domains. Deletion of the E domain of the ER prevented the formation of an ER−tetramer complex, which reflects a novel function of this receptor domain. In transfection experiments, 17-β-estradiol activated transcription from an overERE-containing promoter 4−6 times better than from an ERE-containing promoter. This synergistic effect was observed using either the natural hormone (17-β-estradiol) or xenoestrogens (phenol red, chlordane). We conclude that two overlapping estrogen-responsive elements can elicit synergistic induction of transcription.