Regulatory Effect of circRNA3890 on the Establishment of Receptive Endometrium in Dairy Goats.

Receptive endometrium (RE) is essential for mammalian embryo implantation. The establishment of RE is a complex and precise dynamic process regulated by various cytokines, including non-coding RNAs (miRNAs, lncRNAs, and circRNAs). We identified candidate miR-26b-3p and circRNA3890 from our previous endometrial non-coding RNA sequencing data. CircRNA3890 adsorbs miR-26b-3p and inhibits its activity. Mouse double minute 4 (MDM4) is a target gene of miR-26b-3p, and circRNA3890 up-regulates the expression level of MDM4 by inhibiting the activity of miR-26b-3p in dairy goat endometrial epithelial cells (gEECs) in vitro. circRNA3890/miR-26b-3p/MDM4 could promote the proliferation of gEECs through the p53 signaling pathway. MiR-26b-3p could regulate the expression levels of vascular endothelial growth factor A (VEGFA) and leukemia inhibitory factor (LIF) through MDM4 in gEECs, which contributes to the development of endometrial receptivity. Furthermore, the results showed that miR-26b-3p significantly promoted the development of RE and embryo implantation. These findings demonstrate that circRNA3890 targets and adsorbs miR-26b-3p to relieve MDM4 inhibition and promotes EEC proliferation through the p53 signaling pathway. They reveal the regulatory effect of miR-26b-3p on receptive endometrial development and embryo implantation in vitro and in vivo.