Transcriptomic profiling of canine decidualization and effects evoked by antigestagens on decidualized canine uterine stromal cells

Maternal-stroma derived decidual cells are the single population in the canine placenta expressing the nuclear progesterone (P4) receptor (PGR), rendering them crucial for the maintenance of canine pregnancy. Indeed, decreased circulating P4 levels or blockage of PGR function with antigestagens (e.g., aglepristone), culminates in the termination of canine pregnancy. As an in vitro model for canine decidualization, dog uterine stromal (DUS; Graubner et al., 2017) cells can be decidualized in vitro with cAMP. The antigestagens aglepristone and mifepristone ablate the expression of decidualization markers in DUS cells (e.g., PGR, PRLR, IGF1 or PTGES). In order to study the mechanisms involved in feto-maternal communication during pregnancy and induction of parturition, the goal of the present work was to assess transcriptional changes mediated by decidualization and antigestagens-induced effects in decidualized DUS cells. Decidualization led to the upregulation of 1841 differentially expressed genes (DEGs, P < 0.01, FDR < 0.01) involved in cellular proliferation and adhesion, mesenchymal-epithelial transition, extracellular matrix organization, and vaso- and immunomodulation. The 1475 DEGs downregulated after decidualization were mostly associated with apoptosis and cell migration. In decidualized DUS cells, aglepristone modulated 1400 DEGs and mifepristone 1558 DEGs. Interestingly, only around half of the identified DEGs were modulated uniquely by one of the antigestagens. In both situations, however, PGR-blockage was associated with an inversion of decidualization-induced effects. Comparison between antigestagens-mediated effects and transcriptional changes in the canine placenta at term allowed the identification of 191 DEGs associated with cell proliferation and adhesion, vascularization and immune activity. These findings emphasize the importance of P4/PGR signaling for decidual cells function. Overall design: A total of 4 groups were used. Immortalized Dog Uterine Stromal (DUS) cells were cultured in vitro for 72h either in serum-free medium (non-decidualized control group, n = 3 replicates), or in the presence of 0.5mM dbcAMP (decidualized DUS/cAMP group, n = 3 replicates). Decidualized DUS cells were then treated for 6h in the presence of 1µM of aglepristone or mifepristone (n = 5 replicates for each antigestagen). At the end of each treatment, cells were washed with ice cold PBS and collected for further RNA isolation with Trizol.