Tissue-specific progesterone receptor-chromatin binding and the regulation of progesterone-dependent gene expression.

Progesterone receptor (PGR) co-ordinately regulates ovulation, fertilisation and embryo implantation through tissue-specific actions, but the mechanisms for divergent PGR action are poorly understood. Here we characterised PGR activity in mouse granulosa cells using combined ChIP-seq for PGR and H3K27ac and gene expression microarray. Comparison of granulosa, uterus and oviduct PGR-dependent genes showed almost complete tissue specificity in PGR target gene profiles. In granulosa cells 82% of identified PGR-regulated genes bound PGR within 3 kb of the gene and PGR binding sites were highly enriched in proximal promoter regions in close proximity to H3K27ac-modified active chromatin. Motif analysis showed highly enriched PGR binding to the PGR response element (GnACAnnnTGTnC), but PGR also interacted significantly with other transcription factor binding motifs. In uterus PGR showed far more tendency to bind intergenic chromatin regions and low evidence of interaction with other transcription factors. This is the first genome-wide description of PGR action in granulosa cells and systematic comparison of diverse PGR action in different reproductive tissues. It clarifies finely-tuned contextual PGR-chromatin interactions with implications for more targeted reproductive medicine.