Stromal Pbrm1 mediates chromatin remodeling necessary for embryo implantation in mouse uterus [ATAC-Seq]
Early gestational loss occurs in ~20% of all clinically recognized human pregnancies and is a significant cause of morbidity. Either embryonic or maternal defects can cause loss, but a functioning and receptive uterine endometrium is crucial for embryo implantation. The SWI/SNF remodeling complex containing PBRM1and BRG1 is essential for implantation of the embryonic blastocyst on the wall of the uterus in mice. Although pre-implantation development is unaffected, conditional ablation of Pbrm1 in uterine stromal cells disrupts progesterone pathway and uterine receptivity. Hand2 is a bHLH transcription factor required for embryo implantation. We report a new enhancer of Hand2 in stromal cells that requires PBRM1 for epigenetic histone modifications and coactivator recruitment. In Pbrm1cKO mice, perturbations at the enhancer site compromised Hand2 transcription, disrupts the fibroblast growth factor signaling pathway and prevents normal Stromal- Epithelial crosstalk and embryo implantation. The resultant mutant female mice are infertile and provide insight into potential causes of early pregnancy loss in humans. Overall design: ATAC-seq was performed using  D4 primary uterine stromal cell between control and Pbrm1 cKO mice in order to identify the differentially chromatin accessibility.