Identification and characterization of ART-27, a novel coactivator for the androgen receptor N terminus.
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.
Markus
Steven M
SM
Department of Microbiology, The Kaplan Comprehensive Cancer Center, New York University School of Medicine, New York, New York 10016, USA.
Taneja
Samir S
SS
Logan
Susan K
SK
Li
Wenhui
W
Ha
Susan
S
Hittelman
Adam B
AB
Rogatsky
Inez
I
Garabedian
Michael J
MJ
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins; D005786:Gene Expression Regulation; D006801:Humans; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques
D018797:Cell Cycle Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D011944:Receptors, Androgen; D015534:Trans-Activators; C118920:UXT protein, human