title: A nuclear protein is required for thyroid hormone receptor binding to an inhibitory half-site in the epidermal growth factor receptor promoter.
abstract: The epidermal growth factor (EGF) receptor (EGFR) promoter is negatively regulated by thyroid hormone and retinoic acid. This regulation can be mapped to a 36-basepair GC-rich region of the promoter (EGFR P/E) that functions autonomously as a promoter and an enhancer when placed in front of the thymidine kinase gene TATA element. Direct high affinity binding of the thyroid hormone receptor (T3R) to this element requires a nuclear protein. Through ion exchange chromatography and gel filtration of HeLa nuclear extract, this activity was identified as a protein of approximately 67 kilodaltons. This protein did not bind to DNA alone, but greatly augmented T3R binding to the EGFR P/E sequence in gel mobility shift and DNA precipitation assays. When combined with the T3R auxillary protein (TRAP), the T3R migrated as a larger complex on the DNA. Chemical cross-linking identified this complex as a heterodimer between T3R and TRAP. T3R-TRAP binds to a 7-basepair site in the EGFR P/E (GGGACTC) that has weak homology to a consensus thyroid response element half-site. Thus, on this element, T3R-TRAP heterodimers contact the DNA primarily on a single site that comprises an inhibitory thyroid response element.
authors.affiliation: Department of Medicine, University of California-San Diego, La Jolla 92093-0650.
authors.forename: K L
authors.initials: KL
authors.lastname: Thompson
authors.forename: J B
authors.initials: JB
authors.lastname: Santon
authors.forename: L B
authors.initials: LB
authors.lastname: Shephard
authors.forename: G M
authors.initials: GM
authors.lastname: Walton
authors.forename: G N
authors.initials: GN
authors.lastname: Gill
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002852:Chromatography, Ion Exchange; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004742:Enhancer Elements, Genetic; D066246:ErbB Receptors / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D016385:TATA Box; D013937:Thymidine Kinase / Q000235:genetics; D014284:Triiodothyronine / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011988:Receptors, Thyroid Hormone; D011994:Recombinant Proteins; D014284:Triiodothyronine; D013937:Thymidine Kinase; D066246:ErbB Receptors