title: Ligand induced interaction of thyroid hormone receptor beta with its coregulators.
abstract: Thyroid hormones exert most of their physiological effects through two thyroid hormone receptor (TR) subtypes, TRalpha and TRbeta, which associate with many transcriptional coregulators to mediate activation or repression of target genes. The search for selective TRbeta ligands has been stimulated by the finding that several pharmacological actions mediated by TRbeta might be beneficial in medical conditions such as obesity, hypercholesterolemia and diabetes. Here, we present a new methodology which employs surface plasmon resonance to investigate the interactions between TRbeta ligand binding domain (LBD) complexes and peptides derived from the nuclear receptor interaction motifs of two of its coregulators, SRC2 and DAX1. The effect of several TRbeta ligands, including the TRbeta selective agonist GC-1 and the TRbeta selective antagonist NH-3, were investigated. We also determined the kinetic rate constants for the interaction of TRbeta-T3 with both coregulators, and accessed the thermodynamic parameters for the interaction with DAX1. Our findings suggest that flexibility plays an important role in the interaction between the receptor and its coregulators, and point out important aspects of experimental design that should be addressed when using TRbeta LBD and its agonists. Furthermore, the methodology described here may be useful for the identification of new TRbeta ligands.
authors.affiliation: Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-carlense 400, 13560-970 São Carlos, SP, Brazil. napoleao@mac.com
authors.forename: Napoleão F
authors.initials: NF
authors.lastname: Valadares
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
authors.forename: Richard C
authors.initials: RC
authors.lastname: Garratt
mesh_terms: D000595:Amino Acid Sequence; D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D051958:Nuclear Receptor Coactivator 2 / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D020349:Surface Plasmon Resonance / Q000379:methods; D037042:Thyroid Hormone Receptors beta / Q000819:agonists / Q000378:metabolism*
chemical_list: D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins; D008024:Ligands; C539965:NR0B1 protein, human; D051958:Nuclear Receptor Coactivator 2; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D037042:Thyroid Hormone Receptors beta