Isolation and characterization of a novel ligand-dependent thyroid hormone receptor-coactivating protein.
The thyroid hormone receptor (TR) regulates the expression of target genes upon binding to triiodothyronine (T3) response elements. In the presence of T3, the TR recruits coactivating proteins that both modulate and integrate the ligand response. We report here the cloning of a novel protein using the TR ligand-binding domain as bait in the yeast two-hybrid system. Analysis of a putative full-length clone demonstrates a cDNA sequence that encodes a protein of 920 amino acids with a size of 120 kDa (p120). Alignment with known sequences shows homology to a previously identified protein of unknown function, termed skeletal muscle abundant protein. Interaction studies demonstrate that p120 interacts with the TR AF-2 domain in the presence of ligand through a 111-amino acid region. Northern analysis demonstrates widespread expression in human tissues. Cotransfection assays in CV-1 cells demonstrate that p120 enhances TR-mediated transactivation on multiple T3 response elements in the presence of T3. In addition, CREB-binding protein synergizes with p120 to enhance this effect. When linked to the GAL4 DNA-binding domain, p120 is an activator of transcription alone. Thus, p120 satisfies a number of important criteria as a nuclear receptor coactivator.
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Thyroid Unit, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
Wondisford
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Hollenberg
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D000074183:ATPases Associated with Diverse Cellular Activities; D000123:Acetyltransferases / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001665:Binding Sites; D015415:Biomarkers; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification*; D018797:Cell Cycle Proteins / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D051548:Histone Acetyltransferases; D006801:Humans; D060588:LIM Domain Proteins; D008024:Ligands; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D014158:Transcription, Genetic; D014284:Triiodothyronine / Q000378:metabolism*; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; D000092468:Bromodomain Containing Proteins
D000074183:ATPases Associated with Diverse Cellular Activities; D000123:Acetyltransferases; D048868:Adaptor Proteins, Signal Transducing; D015415:Biomarkers; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004247:DNA; D051548:Histone Acetyltransferases; D060588:LIM Domain Proteins; D008024:Ligands; D009687:Nuclear Proteins; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D014157:Transcription Factors; D014284:Triiodothyronine; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C099139:BRD8 protein, human; D000092468:Bromodomain Containing Proteins; C092282:PSMC5 protein, human; C538859:NCOA1 protein, human