GSE116397
Genome-wide analysis of AR binding and transcriptomic analysis of mesenchymal subsets during prostate development
Prostate organogenesis is regulated by interactions between mesenchymal and epithelial cells, and via androgen signalling though androgen receptors (AR) expressed in mesenchymal cells. However, there is little knowledge of AR target genes and we have used high resolution genomic methods to examine AR function in subsets of mesenchyme during prostate development. Using ChIP-seq, we defined genomic AR binding sites (ARBS) in microdissected mesenchymal tissues of neonatal male and female rats during prostate growth. By comparing female tissue subsets (ventral mesenchymal pad and urethral smooth muscle) with male tissues (ventral prostate and dorsolateral prostate), we were able to identify sexually dimorphic ARBS.  Females had a distinct AR binding profile from males with enrichment of ARBS proximal to gene transcriptional start sites as well as binding to non-classical AR binding sequence motifs. Using both tissue RNA-sequencing and single-cell RNA-sequencing of the same mesenchymal subsets, we identified 128 differentially expressed transcripts between males and females. Comparison of these to ChIP-seq ARBS allowed us to define sexually dimorphic AR target genes.  Selected candidates were validated as sexually dimorphic at both the mRNA and protein level in both rat and human developing prostate tissues by qPCR and western blot. Response to testosterone stimulation was examined using ex vivo rat tissue organ cultures and qPCR. In single cell RNAseq data we observed subpopulations of mesenchymal cells in males and females as well as subpopulations common to both. The distribution of AR and target genes did not follow the subpopulation distribution, suggesting that AR action is not restricted by subset identity.Our study is the first to apply multiple transcriptomic approaches to prostate mesenchyme, and we have identified unique AR targets. We have identified sexually dimorphic, androgen responsive mesenchymal target genes that may underlie sexually dimorphic development of the prostate. We suggest that the analysis of transcription factor binding and transcriptomes in cell subsets will be informative when applied to tumour cells and stroma – since these show similar cellular heterogeneity and subset specific activity. Overall design: Examination of AR binding profile and transcriptomics in developing rat urogenital sinus tissues.