Functional screening of FxxLF-like peptide motifs identifies SMARCD1/BAF60a as an androgen receptor cofactor that modulates TMPRSS2 expression.
Androgen receptor (AR) transcriptional activity is tightly regulated by interacting cofactors and cofactor complexes. The best described cofactor interaction site in the AR is the hormone-induced coactivator binding groove in the ligand-binding domain, which serves as a high-affinity docking site for FxxLF-like motifs. This study aimed at identifying novel AR cofactors by in silico selection and functional screening of FxxLF-like peptide motifs. Candidate interacting motifs were selected from a proteome-wide screening and from a supervised screening focusing on components of protein complexes involved in transcriptional regulation. Of the 104 peptides tested, 12 displayed moderate to strong in vivo hormone-dependent interactions with AR. For three of these, ZBTB16/PLZF, SMARCA4/BRG1, and SMARCD1/BAF60a, the full-length protein was tested for interaction with AR. Of these, BAF60a, a subunit of the SWI/SNF chromatin remodeling complex, displayed hormone-dependent interactions with AR through its FxxFF motif. Vice versa, recruitment of BAF60a by the AR required an intact coactivator groove. BAF60a depletion by small interfering RNA in LNCaP cells demonstrated differential effects on expression of endogenous AR target genes. AR-driven expression of TMPRSS2 was almost completely blocked by BAF60a small interfering RNA. In summary, our data demonstrate that BAF60a directly interacts with the coactivator groove in the AR ligand-binding domain via its FxxFF motif, thereby selectively activating specific AR-driven promoters.
van de Wijngaart
Dennis J
DJ
Department of Urology, Josephine Nefkens Institute, Erasmus Medical College, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Dubbink
Hendrikus J
HJ
Molier
Michel
M
de Vos
Carola
C
Trapman
Jan
J
Jenster
Guido
G
D020816:Amino Acid Motifs; D002460:Cell Line; D045744:Cell Line, Tumor; D002868:Chromosomal Proteins, Non-Histone; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry*; D011471:Prostatic Neoplasms / Q000378:metabolism; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D002868:Chromosomal Proteins, Non-Histone; D010455:Peptides; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; C109786:SMARCD1 protein, human; D014157:Transcription Factors; D012697:Serine Endopeptidases; C421305:TMPRSS2 protein, human