Expression And Regulation Of Runx In Mouse Uterus

Embryo implantation involves the consanguineous interaction between areceptive uterus and an implantation-competent blastocyst, which occurs in a briefperiod known as the window of implantation. Although numerous of cellular eventsand molecular pathways involved in embryo–uterine crosstalk during implantationhave been affirmed through gene expression studies and transgenosis mouse models,an all-around understanding of the nature of embryo implantation is still missing. TheRunx family of transcription factor consists of three known members (RUNX1–3) thatshare a high degree of sequence homology within most of their coding regions.According to our previous date of implantation and decidualization gene chips, theexpression of Runx1, Runx2, Runx3was remarkably up-regulated compared withcontrol group. In situ hybridization, real-time PCR, siRNA, gelatin zymography,bisulfite-sequencing PCR was preformed to detect the expression of Runx in mouseuterus during early pregnancy. We also used pseudopregnancy, artificialdecidualization and delayed implantation and activation, hormonal treatment modelsto study the regulation of Runx in uterus. In vitro cultured uterine stromal cells, weexamined the regulation of steroid hormones, cAMP and induced decidualization onRunx expression. Using bisulfite-sequencing PCR, the methylation level of Runx3promoter was also investigated.Our data suggest that Runx1may play an important role during mouse embryoimplantation and decidualization. Its expression was affected by the activationembryos. In vitro cultured uterine stromal cells, E and P can inhibite the expression ofRunx1, but ICI182,780and RU486may return this effct. In the uterine stromal cells,cAMP pathway can regulate the expression of Runx1gene. Down-regulation theexpression of Runx1gene by siRNA can reduce the levels of COX-2, mPEGs. Runx2 was involved in embryo implantation and decidual process. Down-regulation theexpression of Runx2gene by siRNA in vivo and in vitro, the results showed that itcan not affecte the number of embryo implantation but can reduce the levels ofmmp-9, not COX-2, VEGF. Estrogen and progesterone can control Runx2throughtheir receptors, and in the process of decidualization Runx2may be involved in thereconstruction of extracellular matrix. Runx3may be related to immune-adjustmentfunction during mouse implantation and decidualization. E2treatment can decreaseRunx3expression in mouse endometrial stromal cells although E2can induce theexpression of Runx3in the uterine luminal epithelium. Bisulfite-sequencing PCRshowed that the methylation level of Runx3promoter increased to73.8%after E2exposure in vitro. The methylation of Runx3promoter may be involved in genesilencing.The analysis of spatial and temporal expression pattern of Runx indicatesnon-redundant functions during mouse embryo implantation and decidualization.