Endocrine Abstracts

Background: Decidualization, a crucial process for successful pregnancy establishment and maintenance, involves endometrial stromal cell differentiation. This process is orchestrated by estradiol (E2), progesterone, and other stimuli that increase intracellular cyclic adenosine monophosphate (cAMP) levels. The progesterone receptor (PR) plays a pivotal role in regulating decidualization, and alterations in its expression are linked to endometrial pathologies. However, the mechanisms governing PR gene (PGR) expression in endometrial stromal cells during decidualization are not fully understood. This study aimed to identify the mechanisms of PGR expression regulation in immortalized human endometrial stromal cells.

Methods: Immortalized human endometrial stromal cells (T-hESC, ATCC, CRL4003) were exposed to individual and combined treatments of E2, medroxyprogesterone (MPA), and cAMP. To understand the underlying action mechanisms of the decidualization stimulus components, we examined the effect of estrogen receptors and PR antagonists, as well as a Protein Kinase A (PKA) inhibitor. We evaluated the expression of PGR isoforms and decidualization-associated genes by RT-qPCR. ChIP-seq and 4C experiments were also performed to identify putative distal regulatory regions involved in PGR expression in T-hESC treated with E2, MPA, and cAMP (EMC).

Results: The expression of PGR-AB and PGR-B was induced after 24 hours of treatment with EMC compared to the vehicle. Interestingly, cAMP induced PGR-AB and PGR-B expression by activating the PKA signaling pathway, while MPA downregulated their expression through the PR. Furthermore, four distal regions interacting with the PGR promoter were identified, three characterized by the presence of H3K4me1 and an increase in the enrichment of H3K27ac when T-hESC were treated with EMC for 24 hours.

Conclusion: This study provides evidence that during in vitro decidualization with EMC, cAMP plays a crucial role in inducing the expression of PGR-AB and PGR-B through PKA signaling pathway. Moreover, the identification of distal regions interacting with the PGR promoter, enriched with H3K4me1 and H3K27ac, suggests the existence of complex networks of genetic regulation influencing in vitro decidualization in T-hESC cells.

Acknowledgments: We acknowledge CONACyT (Grant Number A1-S-26749), INPer (Grant Number 571, 3000—20109-01—571-17), UNAM-PAPIIT (Grant Number IA209520), and UNAM-PAEP.