MSX1 is an important member of the muscle segment homeobox gene (Msh) family and acts as a transcription factor to regulate tissue plasticity, yet its role in goat endometrium remodeling remains elusive. In this study, an immunohistochemical analysis showed that MSX1 was mainly expressed in the luminal and glandular epithelium of goat uterus, and the MSX1 expression was upregulated in pregnancy at days 15 and 18 compared with pregnancy at day 5. In order to explore its function, goat endometrial epithelial cells (gEECs) were treated with 17 β-estrogen (E₂), progesterone (P₄), and/or interferon-tau (IFNτ), which were used to mimic the physiological environment of early pregnancy. The results showed that MSX1 was significantly upregulated with E₂- and P₄-alone treatment, or their combined treatment, and IFNτ further enhanced its expression. The spheroid attachment and PGE2/PGF2α ratio were downregulated by the suppression of MSX1. The combination of E₂, P₄, and IFNτ treatment induced the plasma membrane transformation (PMT) of gEECs, which mainly showed the upregulation of N-cadherin (CDH2) and concomitant downregulation of the polarity-related genes (ZO-1, α-PKC, Par3, Lgl2, and SCRIB). The knockdown of MSX1 partly hindered the PMT induced by E₂, P₄, and IFNτ treatment, while the upregulation of CDH2 and the downregulation of the partly polarity-related genes were significantly enhanced when MSX1 was overexpressed. Moreover, MSX1 regulated the CDH2 expression by activating the endoplasmic reticulum (ER) stress-mediated unfolded protein response (UPR) pathway. Collectively, these results suggest that MSX1 was involved in the PMT of the gEECs through the ER stress-mediated UPR pathway, which affects endometrial adhesion and secretion function.

Prostaglandin E₂ (PGE₂) plays a critical role in regulating uterine endometrial function and supporting embryonic development during early pregnancy in ruminants. However, its precise roles in shaping the uterine microenvironment remain unclear. Herein, 1 mg PGE₂ was infused daily into the uterus of dairy heifers from days 12 to 14 of the estrus cycle. ULF was subsequently collected for integrated proteomic, metabolomic, and targeted lipidomic analyses. In addition, bovine endometrial epithelial cells were used to evaluate the effects of PGE₂ on epithelial adhesion and responsiveness to interferon tau (IFNT). PGE₂ infusion resulted in 909 differentially abundant proteins (DAPs), which are primarily associated with early embryonic development, immune regulation, and cell adhesion. Untargeted metabolomics analysis identified 587 altered metabolites, which were enriched in sphingolipid, arachidonic acid, phenylalanine, and tryptophan metabolism. Proteomic–metabolomic analyses showed that these alterations were primarily associated with early embryonic development, immune regulation, and cell adhesion. Targeted lipidomic analysis showed a global reduction in lipid accumulation, with glycerophospholipid metabolism and choline metabolism most significantly affected. In vitro, PGE₂ reduced epithelial microvilli density, increased osteopontin (OPN) expression, and decreased the expression of junctional proteins (zona occludens-1 (ZO-1), E-cadherin (CDH1), and fibronectin 1 (FN1)). Moreover, PGE₂ enhanced the responsiveness of bEECs to IFNT by interferon alpha/beta receptor 1 (IFNAR1) and IFNAR2, and prostaglandin E receptor 4 (PTGER4) was identified as the primary receptor mediating this response. Collectively, these findings suggest that PGE₂ may modulate lipid metabolism and adhesion-related processes in the endometrium and influence endometrial responsiveness to IFNT, providing insights into molecular mechanisms associated with pregnancy establishment in dairy cows.