SOX17 regulates uterine epithelial-stromal crosstalk acting via a distal enhancer upstream of Ihh [array]

Mammalian embryo development is dependent on the ability of the uterus to allow and support the implantation of the embryo. Here we demonstrate that ablation of Sox17 specifically in the uterine epithelium results in altered uterine epithelial cell proliferation, uterine gland development and embryo implantation. Uteri lacking Sox17 showed reduction in LIF and IHH signaling which are critical for embryo implantation. ChIP-seq analysis demonstrated that SOX17 binds to a region 19kb 5’ to the Ihh locus. In vivo deletion of this enhancer by the CRISPR-Cas technology reduced Ihh expression in uteri and altered proper endometrial epithelial-stromal interactions required for pregnancy leading to compromised fertility. The SOX17 binding peak at 19kb from the Ihh promoter also bound GATA2, FOXA2 and PGR. Bioinformatic analysis of regions overlapping SOX17, GATA2, FOXA2 and PGR bindings shows 737 genes with these common binding sites. This cluster of transcription factors identified in this enhancer region may represent a combination of regulatory elements essential for uterine epithelial gene expression and differentiation. Mice with ablation of Sox17 in the uterine epithelium and littermate controls were mated to male mice of proven fertility. Upon the presence of the post-coital plug (Gestational Day 0.5, GD0.5), mice were sacrificed 3 days later (GD3.5) and uterine horns (embryo were flushed out) were harvested and frozen. RNA was isolated from the uterus. An Agilent RNA microarray was performed on 3 biological samples per genotype.