Identification of cis-acting elements that regulate expression of the progesterone receptor gene PGR in the uterus.

The steroid hormone progesterone regulates a wide range of functions in the uterus, including menstruation, pregnancy establishment, pregnancy maintenance, and labor. The cellular effects of progesterone are mediated by the nuclear progesterone receptor (PGR). Progesterone resistance, a decreased cellular response to progesterone,is implicated in a wide range of pathologies including endometriosis, preterm birth, and endometrial cancer. Up to 10% of females within reproductive age are impacted by endometriosis, and no cure is available. This study hypothesizes that misregulation of PGR by upstream regulators is a potential cause of progesterone resistance. However, much remains unknown about the regulation of PGR expression, including the location of enhancers and the identity of transcriptional regulators that control PGR expression. In this study, candidate regulatory elements of PGR were identified by integrative analysis of genomic data, and their function was tested using the CRISPR activation system, with PGR mRNA levels as the readout. Using these methods, two PGR enhancers located at the PGR 3’ untranslated region and 200 kbs upstream of the PGR transcription start site were identified. These enhancers permitted the identification of candidate upstream regulators of PGR expression in the uterus, including GATA2, ARID1A, KLF9, and ESR1. Activation of ESR1 increased PGR mRNA levels in the presence of estradiol in cultured uterine cells. Through the discovery of PGR regulators, we can improve our understanding of molecular mechanisms of progesterone resistance. Ultimately, these regulators could be evaluated in cases of progesterone resistance and targeted in the development of therapies.