Genome-wide analysis reveals porcine LIFR regulated by DNA methylation promotes the implantation process via the STAT3 signaling.

Embryo-uterine interaction during embryo implantation depends on the coordinated expression of numerous genes in the receptive endometrium. While DNA methylation is known to play a significant role in controlling gene expression, specific molecular mechanisms underlying this regulatory event remain elusive in early porcine pregnancy. Here, we investigated the genome-wide DNA methylation landscape in the Yorkshire and Meishan pig's endometrium. The results revealed a higher degree of DNA methylation modifications on gene promoter regions on day 32 of pregnancy compared to that on day 18 of pregnancy. By integrating the mRNA and methylation profiles, leukemia inhibitory factor receptor (LIFR) was identified as a differentially methylated and expressed gene, crucial in early pregnancy. LIFR expression is epigenetically silenced via promoter hypermethylation from days 18 to 32 of pregnancy. Moreover, functional assays demonstrated that LIFR knockdown inhibited the proliferation, adhesion, and migration of endometrial epithelial cells (EECs) and downregulated the expression of STAT3 signaling and pregnancy-related genes. In vivo studies further revealed a reduction of implanted mouse embryos upon loss of function of LIFR. Furthermore, RUNX1 up-regulates LIFR expression by binding to the differentially methylated region (DMR) of the LIFR promoter. High levels of RUNX1T1, in turn, recruit RUNX1/HDAC1/DNMTs to assemble a regulatory complex that silences LIFR expression through the same locus. Collectively, our findings shed light on the role of dynamic DNA methylation and the epigenetic regulation of LIFR on embryo implantation in early swine pregnancy.