title: Identification of a novel testicular orphan receptor-4 (TR4)-associated protein as repressor for the selective suppression of TR4-mediated transactivation.
abstract: Although many co-activators have been identified for various nuclear receptors, relatively fewer co-repressors have been isolated and characterized. Here we report the identification of a novel testicular orphan nuclear receptor-4 (TR4)-associated protein (TRA16) that is mainly localized in the nucleus of cells as a repressor to suppress TR4-mediated transactivation. The suppression of TR4-mediated transactivation is selective because TRA16 shows only a slight influence on the transactivation of androgen receptor, glucocorticoid receptor, and progesterone receptor. Sequence analysis shows that TRA16 is a novel gene with 139 amino acids in an open reading frame with a molecular mass of 16 kDa, which did not match any published gene sequences. Mammalian two-hybrid system and co-immunoprecipitation assays both demonstrate that TRA16 can interact strongly with TR4. The electrophoretic mobility shift assay suggests that TRA16 may suppress TR4-mediated transactivation via decreased binding between the TR4 protein and the TR4 response element on the target gene(s). Furthermore, TRA16 can also block the interaction between TR4 and TR4 ligand-binding domain through interacting with TR4-DNA-binding and ligand-binding domains. These unique suppression mechanisms suggest that TRA16 may function as a novel repressor to selectively suppress the TR4-mediated transactivation.
authors.affiliation: George Whipple Laboratory for Cancer Research Department of Pathology, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Yang
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Tiefei
authors.initials: T
authors.lastname: Dong
authors.forename: Eungseok
authors.initials: E
authors.lastname: Kim
authors.forename: Wen-Jye
authors.initials: WJ
authors.lastname: Lin
authors.forename: Chawnshang
authors.initials: C
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D015723:Gene Library; D017930:Genes, Reporter; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism*; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D018076:DNA, Complementary; C490515:NR2C2 protein, human; C472782:NR2C2AP protein, human; C490514:Nr2c2 protein, mouse; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011944:Receptors, Androgen; D011965:Receptors, Glucocorticoid; D011980:Receptors, Progesterone; D011987:Receptors, Steroid; D011988:Receptors, Thyroid Hormone; D012097:Repressor Proteins