A coregulatory role for the TRAP-mediator complex in androgen receptor-mediated gene expression.
The human thyroid hormone receptor-associated protein (TRAP)-Mediator complex was originally identified as a large multimeric complex that copurifies with the thyroid hormone receptor (TR) from HeLa cells and markedly enhances TR-mediated transcription in vitro. More recent studies have implicated TRAP-Mediator as a coactivator for a broad range of nuclear hormone receptors as well as other classes of transcriptional activators. Here we present evidence that TRAP-Mediator plays a functional role in androgen receptor (AR)-mediated transcription. We show that several subunits of the complex ligand-dependently coimmunoprecipitate with AR from both prostate cancer LNCaP cells and from HeLa cells stably transfected with AR. The 220-kDa subunit of the complex (TRAP220) can contact the ligand-binding domain of AR in vitro, possibly implicating TRAP220 involvement in targeting AR to the holocomplex. Consistent with a TRAP-Mediator coactivator role, transient overexpression of the TRAP220, TRAP170, and TRAP100 subunits enhanced ligand-dependent transcription by AR in cultured cells. Finally, chromatin immunoprecipitation assays show that TRAP220 is recruited to the androgen-responsive prostate-specific antigen gene promoter in vivo in ligand-stimulated LNCaP cells. Collectively, these data suggest that TRAP-Mediator may play an important coregulatory role in AR-mediated gene expression.
Wang
Qianben
Q
Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Sharma
Dipali
D
Ren
Yunsheng
Y
Fondell
Joseph D
JD
D000951:Antigens, Neoplasm / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins; D002843:Chromatin / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008297:Male; D056892:Mediator Complex; D056913:Mediator Complex Subunit 1; D011401:Promoter Regions, Genetic; D017430:Prostate-Specific Antigen / Q000235:genetics; D011471:Prostatic Neoplasms; D021122:Protein Subunits / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011944:Receptors, Androgen / Q000502:physiology*; D011988:Receptors, Thyroid Hormone / Q000378:metabolism; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; D001426:Bacterial Proteins; D002352:Carrier Proteins; D002843:Chromatin; C538855:MED1 protein, human; C503845:MED24 protein, human; C538713:Med17 protein, human; D056892:Mediator Complex; D056913:Mediator Complex Subunit 1; C079092:MtrB protein, Bacteria; D021122:Protein Subunits; D016601:RNA-Binding Proteins; D011944:Receptors, Androgen; D011988:Receptors, Thyroid Hormone; D015534:Trans-Activators; D014157:Transcription Factors; D017430:Prostate-Specific Antigen