Identification and characterization of ART-27, a novel coactivator for the androgen receptor N terminus

• Published in: Molecular biology of the cell 2002-02, Vol.13 (2), p.670-682
• Main Authors: Markus, Steven M, Taneja, Samir S, Logan, Susan K, Li, Wenhui, Ha, Susan, Hittelman, Adam B, Rogatsky, Inez, Garabedian, Michael J
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Cell Cycle Proteins; Gene Expression Regulation; Humans; Molecular Chaperones; Molecular Sequence Data; Neoplasm Proteins; Receptors, Androgen - genetics; Receptors, Androgen - metabolism; Trans-Activators - genetics; Trans-Activators - metabolism; Tumor Cells, Cultured; Two-Hybrid System Techniques
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.01-10-0513

The androgen receptor (AR) is a ligand-regulated transcription factor that stimulates cell growth and differentiation in androgen-responsive tissues. The AR N terminus contains two activation functions (AF-1a and AF-1b) that are necessary for maximal transcriptional enhancement by the receptor; however, the mechanisms and components regulating AR transcriptional activation are not fully understood. We sought to identify novel factors that interact with the AR N terminus from an androgen-stimulated human prostate cancer cell library using a yeast two-hybrid approach designed to identify proteins that interact with transcriptional activation domains. A 157-amino acid protein termed ART-27 was cloned and shown to interact predominantly with the AR(153-336), containing AF-1a and a part of AF-1b, localize to the nucleus and increase the transcriptional activity of AR when overexpressed in cultured mammalian cells. ART-27 also enhanced the transcriptional activation by AR(153-336) fused to the LexA DNA-binding domain but not other AR N-terminal subdomains, suggesting that ART-27 exerts its effect via an interaction with a defined region of the AR N terminus. ART-27 interacts with AR in nuclear extracts from LNCaP cells in a ligand-independent manner. Interestingly, velocity gradient sedimentation of HeLa nuclear extracts suggests that native ART-27 is part of a multiprotein complex. ART-27 is expressed in a variety of human tissues, including sites of androgen action such as prostate and skeletal muscle, and is conserved throughout evolution. Thus, ART-27 is a novel cofactor that interacts with the AR N terminus and plays a role in facilitating receptor-induced transcriptional activation.