Project description:The epithelium lining the epididymis has a pivotal role in ensuring a luminal environment that can support normal sperm maturation. Many of the individual genes that encode proteins involved in establishing the epididymal luminal fluid are well characterized. They include ion channels, ion exchangers, transporters and solute carriers. However, the molecular mechanisms that coordinate expression of these genes and modulate their activities in response to biological stimuli are less well understood. To identify cis-regulatory elements for genes expressed in human epididymis epithelial cells we generated genome-wide maps of open chromatin by DNase-seq. This analysis identified 33,542 epididymis-selective DNase I hypersensitive sites (DHS), which were not evident in five cell types of different lineages. Identification of genes with epididymis-selective DHS at their promoters revealed gene pathways that are active in immature epididymis epithelial cells. These include processes correlating with epithelial function and also others with specific roles in the epididymis including retinol metabolism and ascorbate and aldarate metabolism. Peaks of epididymis-selective chromatin were seen in the androgen receptor gene and the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which has a critical role in regulating ion transport across the epididymis epithelium. In silico prediction of transcription factor binding sites that were over-represented in epididymis-selective DHS identified epithelial transcription factors including ELF5 and ELF3, the androgen receptor, Pax2 and Sox9, as components of epididymis transcriptional networks. Active genes, which are targets of each transcription factor, reveal important biological processes in the epididymis epithelium. HEE cells were cultured as described previously (Harris and Coleman 1989). RNA was isolated by Trizol extraction from three primary cultures of HEE cells. Total RNA was purified by Millipore Microcon YM-100 filter centrifugation and shipped to MoGene, MO, for gene expression analysis on Nimblegen 4 x 72K HG18 60mer arrays. This submission represents transcriptome component of study.

Project description:STUDY QUESTION:What is the transcriptional network governed by the androgen receptor (AR) in human epididymis epithelial (HEE) cells from the caput region and if the network is tissue-specific, how is this achieved? SUMMARY ANSWER:About 200 genes are differentially expressed in the caput HEE cells after AR activation; the AR transcriptional network is tissue-specific and may be mediated in part by distinct AR co-factors including CAAT-enhancer binding protein beta (CEBPB) and runt-related transcription factor 1 (RUNX1). WHAT IS KNOWN ALREADY:Little is known about the AR transcriptional program genome wide in HEE cells, nor its co-factors in those cells. AR has been best studied in the prostate gland epithelium and prostate cancer cell lines, due to the important role of this factor in prostate cancer. However AR-associated differentially expressed genes (DEGs) and AR co-factors have not yet been compared between human epididymis and prostate epithelial cells. STUDY DESIGN, SIZE, DURATION:Caput HEE cells from two donors were exposed to the synthetic androgen R1881 at 1 nM for 12-16 h after 72 h of hormone starvation. PARTICIPANTS/MATERIALS, SETTING, METHODS:Chromatin was prepared from R1881-treated and vehicle control HEE cells. AR-associated chromatin was purified by chromatin immunoprecipitation (ChIP) and AR occupancy genome wide was revealed by deep sequencing (ChIP-seq). Two independent biological replicates were performed. Total RNA was prepared from R1881 and control-treated HEE cells and gene expression profiles were documented by RNA-seq. The interaction of the potential novel AR co-factors CEBPB and RUNX1, identified through in-silico motif analysis of AR ChIP-seq data, was examined by ChIP-qPCR after siRNA-mediated depletion of each co-factor individually or simultaneously. MAIN RESULTS AND THE ROLE OF CHANCE: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 CEBPB and 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 CEBPB may be a co-activator. These data suggest a novel AR transcriptional network governs differentiated functions of the human epididymis epithelium. LARGE SCALE DATA:AR ChIP-seq and RNA-seq data are deposited at GEO: GSE109063. LIMITATIONS, REASONS FOR CAUTION:There is substantial donor-to-donor variation in primary HEE cells cultures. We applied stringent statistical tests with a false discovery rate (FDR) of 0.1% for ChIP-seq and standard pipelines for RNA-seq so it is possible that we have missed some AR-regulated genes that are important in caput epididymis function. WIDER IMPLICATIONS OF THE FINDINGS:Our data suggest that a novel AR transcriptional network governs differentiated functions of the human epididymis epithelium. Since this cell layer has a critical role in normal sperm maturation, the results are of broader significance in understanding the mechanisms underlying the maintenance of fertility in men. STUDY FUNDING/COMPETING INTERESTS:This work was funded by the National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Development: R01 HD068901 (PI: Harris). The authors have no competing interests to declare.

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A novel transcriptional network for the Androgen Receptor in human epididymis epithelial cells

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