A novel transcriptional network for the Androgen Receptor in human epididymis epithelial cells [RNA-Seq]

The androgen receptor (AR) has a pivotal role in regulating gene expression in the male reproductive system. Due to the involvement of AR in prostate cancer, its role is best studied in the prostate gland epithelium and prostate cancer cell lines. Here we investigate the transcriptional program of AR in normal human epididymis epithelial (HEE) cells. After AR stimulation of caput HEE cells with the synthetic androgen R1881, AR targets were revealed with RNA-sequencing. Next, AR occupancy genome-wide was determined in control or R1881-stimulated HEE cells by chromatin immunoprecipitation and deep sequencing (ChIP-seq). The results identify about 200 genes that are differentially expressed (DEGs) in HEE cells after AR activation. Some of these DEGs show occupancy of AR at their promoters or cis-regulatory elements suggesting direct regulation. However there is little overlap in AR-associated DEGs between HEE and prostate epithelial cells. Inspection of over-represented motifs in AR ChIP-seq peaks identified CAAT-enhancer binding protein beta (CEBPB) and Runt-related transcription factor 1 (RUNX1) as potential co-factors, with no evidence for FOXA1, which is an important co-factor in the prostate epithelium. CEBPB and RUNX1 ChIP-seq in HEE cells showed that both these factors often occupied AR-binding sites, though rarely simultaneously. Further analysis at a single AR-regulated locus (FK506-binding protein 5, FKPB5) suggests that RUNX1 may inhibit AR occupancy, while CEBP appears to be a co-activator. These data suggest a novel AR transcriptional network governs differentiated functions of the human epididymis epithelium. Examination of AR cistrome in primary human epididymis cells with or without R1881 treatment