The NPM1/p53 nucleolar stress signaling pathway promotes endometrial receptivity establishment in goats via the Wnt/β-catenin pathway.

In goats, embryo implantation is superficial, making endometrial receptivity a key determinant of pregnancy success. Although the NPM1/p53 nucleolar stress pathway is involved in endometrial receptivity in mice and humans, its role in ruminants remains unknown. Using early-pregnancy goat models, in vitro-induced goat endometrial epithelial cells (gEECs), and low-dose Actinomycin D (ActD) to trigger nucleolar stress, we investigated this signaling axis in goat endometrial receptivity. Compared with pre-receptive Day 10 endometrium, receptive Day 16 endometrium showed increased NPM1 expression in epithelial cells, accompanied by its translocation from the nucleolus to the nucleoplasm. Markers of nucleolar stress (p53, p21, MDM2) were upregulated, while pre-rRNA levels were reduced. In gEECs, low-dose ActD effectively activated the NPM1/p53 pathway, which was also activated during in vitro receptivity induction using estrogen, progesterone, and interferon-tau. Activation of this pathway by ActD increased receptivity markers (HOXA10, HOXA11, MSX1), recapitulating changes seen during receptivity induction, whereas Npm1 knockdown attenuated this effect. ActD treatment also activated Wnt/β-catenin signaling. Pretreatment with the Wnt/β-catenin inhibitor Adavivint markedly reduced ActD-induced upregulation of HOXA10 and HOXA11 proteins but did not affect p53 expression. Together, these results indicate that the NPM1/p53 nucleolar stress pathway promotes endometrial receptivity in goats, at least in part, through the Wnt/β-catenin pathway. This work expands understanding of endometrial receptivity in ruminants and provides a basis for further investigation of nucleolar stress in reproductive regulation.