title: Half-site arrangement of hybrid glucocorticoid and thyroid hormone response elements specifies thyroid hormone receptor complex binding to DNA and transcriptional activity.
abstract: Thyroid hormone receptors bind to thyroid hormone response elements (TREs) as heterodimers with 3,5,3'-L-triiodothyronine (T3) receptor auxiliary protein (TRAP) and retinoid X receptors (RXRs). Currently, it is not known whether TR/TRAP or TR/RXR heterodimers need to bind to both TRE half-sites and whether there is a preferred orientation for TR/RXR heterodimer binding to TREs or transcriptional activation. Accordingly, we created a mutant TR alpha (TR-P box) by changing 3 amino acids in the P box region of the first zinc finger of the DNA-binding domain to that of the glucocorticoid receptor (GR), and we examined wild-type TR alpha and TR-P box complex binding to hybrid response elements containing TRE and glucocorticoid receptor element (GRE) half-sites arranged as a direct repeat with a four-nucleotide gap. TR-P box/RXR heterodimers selectively bound to the hybrid response elements in which GRE half-site was the downstream half-site, whereas TR alpha/RXR bound to hybrid response elements in which GREs were in either position. Additionally, TR/TRAP or TR/RXR heterodimer required two half-sites for binding to DNA, with strong binding to at least one of the half-sites. Last, co-transfection assays and methylation interference studies using the hybrid response elements suggest that the sequential arrangement of strong and weak half-sites in the TRE may be a critical determinant of TR/RXR heterodimer binding and transcriptional activation.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.
authors.forename: P M
authors.initials: PM
authors.lastname: Yen
authors.forename: M
authors.initials: M
authors.lastname: Ikeda
authors.forename: E C
authors.initials: EC
authors.lastname: Wilcox
authors.forename: J H
authors.initials: JH
authors.lastname: Brubaker
authors.forename: R A
authors.initials: RA
authors.lastname: Spanjaard
authors.forename: A
authors.initials: A
authors.lastname: Sugawara
authors.forename: W W
authors.initials: WW
authors.lastname: Chin
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism*; D008969:Molecular Sequence Data; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D047488:Retinoid X Receptors; D013963:Thyroid Hormones / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D005938:Glucocorticoids; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone; D047488:Retinoid X Receptors; D013963:Thyroid Hormones; D014157:Transcription Factors; D004247:DNA