Functional effects of BMPR1B in porcine endometrium provides novel insights into the high fecundity of Taihu pigs.

Litter size in pigs is affected by factors such as ovulation number, embryonic survival, and uterine environment conditions. Endometrial epithelial and stromal cells represent the first site of contact between the embryo and sows; therefore, dynamic changes in the growth and development of these cells are among the major factors affecting the intrauterine environment and implantation. Bone morphogenetic protein receptor type-1B (BMPR1B) is a receptor of the bone morphogenetic protein (BMP) family that has been identified as a candidate gene for reproductive traits in pigs. In our previous study, we used whole-genome resequencing to identify BMPR1B as a candidate gene affecting sow litter size in Taihu pigs and revealed the transcriptional regulation of BMPR1B in the endometrium. However, the functional role of BMPR1B in the growth and development of the endometrium in pigs has not been comprehensively elucidated. In this study, we isolated, characterized, and immortalized Meishan pig endometrial cells, and systematically explored the biological function of BMPR1B using a cell model. BMPR1B promoted cell proliferation and migration of endometrial stromal cells but inhibited that of endometrial epithelial cells. Transcriptome sequencing revealed potential pathways through which BMPR1B influences the growth and development of endometrial cells, including vascular system development, gland morphology, cell migration and adhesion, and reproductive system development. Moreover, the outstanding uterine function of Meishan pigs from endometrial genomic aspects was performed elucidated through CUT&Tag experiments. Most biological processes, including reproductive system development, embryonic morphogenesis, and angiogenesis, were enriched by genes that were differentially bound by enhancer markers. These findings provide a valuable resource for future research on the mechanisms underlying the excellent uterine function in Meishan pigs.