title: GCN5 and ADA adaptor proteins regulate triiodothyronine/GRIP1 and SRC-1 coactivator-dependent gene activation by the human thyroid hormone receptor.
abstract: We have used yeast genetics and in vitro protein-protein interaction experiments to explore the possibility that GCN5 (general control nonrepressed protein 5) and several other ADA (alteration/deficiency in activation) adaptor proteins of the multimeric SAGA complex can regulate T3/GRIP1 (glucocorticoid receptor interacting protein 1) and SRC-1 (steroid receptor coactivator-1) coactivator-dependent activation of transcription by the human T3 receptor beta1 (hTRbeta1). Here, we show that in vivo activation of a T3/GRIP1 or SRC-1 coactivator-dependent T3 hormone response element by hTRbeta1 is dependent upon the presence of yeast GCN5, ADA2, ADA1, or ADA3 adaptor proteins and that the histone acetyltransferase (HAT) domains and bromodomain (BrD) of yGCN5 must be intact for maximal activation of transcription. We also observed that hTRbeta1 can bind directly to yeast or human GCN5 as well as hADA2, and that the hGCN5(387-837) sequence could bind directly to either GRIP1 or SRC-1 coactivator. Importantly, the T3-dependent binding of hTRbeta1 to hGCN5(387-837) could be markedly increased by the presence of GRIP1 or SRC1. Mutagenesis of GRIP1 nuclear receptor (NR) Box II and III LXXLL motifs also substantially decreased both in vivo activation of transcription and in vitro T3-dependent binding of hTRbeta1 to hGCN5. Taken together, these experiments support a multistep model of transcriptional initiation wherein the binding of T3 to hTRbeta1 initiates the recruitment of p160 coactivators and GCN5 to form a trimeric transcriptional complex that activates target genes through interactions with ADA/SAGA adaptor proteins and nucleosomal histones.
authors.affiliation: Samuel Lunenfeld Research Institute, University of Toronto Medical School, Mount Sinai Hospital, Ontario, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Anafi
authors.forename: Y F
authors.initials: YF
authors.lastname: Yang
authors.forename: N A
authors.initials: NA
authors.lastname: Barlev
authors.forename: M V
authors.initials: MV
authors.lastname: Govindan
authors.forename: S L
authors.initials: SL
authors.lastname: Berger
authors.forename: T R
authors.initials: TR
authors.lastname: Butt
authors.forename: P G
authors.initials: PG
authors.lastname: Walfish
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins / Q000502:physiology; D005656:Fungal Proteins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D005816:Genetic Complementation Test; D051548:Histone Acetyltransferases; D006801:Humans; D046911:Macromolecular Substances; D008957:Models, Genetic; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D010446:Peptide Fragments / Q000378:metabolism; D010940:Plant Proteins / Q000502:physiology; D011494:Protein Kinases / Q000502:physiology*; D011988:Receptors, Thyroid Hormone / Q000187:drug effects* / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014284:Triiodothyronine / Q000502:physiology*; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D051548:Histone Acetyltransferases; D046911:Macromolecular Substances; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D010446:Peptide Fragments; D010940:Plant Proteins; D011494:Protein Kinases; D011988:Receptors, Thyroid Hormone; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D014284:Triiodothyronine; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C090575:ADA2 protein, S cerevisiae; C106162:HFI1 protein, S cerevisiae; C498001:NCOA2 protein, human; C083323:NGG1 protein, S cerevisiae; C099690:SPT20 protein, S cerevisiae; C075582:SPT3 protein, S cerevisiae; C093107:SPT7 protein, S cerevisiae; C089445:SPT8 protein, S cerevisiae; C097695:TADA2A protein, human; C501392:GCN5 protein, S cerevisiae; C501179:KAT2A protein, human; C538859:NCOA1 protein, human