miR-135a/b-HOXA10调控IVF子宫内膜容受性的作用及机制

Endometrial receptivity is the key factor to establish pregnancy. During controlled ovarian stimulation in vitro fertilization (IVF), super-physiological concentrations of estrogen, progesterone may influence the endometrial receptivity. However, the precise mechanism remains unclear. Our previous study indicated that progesterone elevation with high estrogen levels on the day of HCG administration resulted in low rates of pregnancy and live birth, but the embryo quality was not affected, we thus hypothesized that impaired endometrial receptivity may affect embryo implantation. Meanwhile, miR-135a/b expression in endometrium was elevated during implantation window. We found that one of the potential target genes of miR-135a/b is HOXA 10 via bioinformatics analysis. Interestingly, previous studies have demonstrated that HOXA10 and its target genes, such as integrin β3、EMX2 , and PCAF, play an important role in the construction of endometrial receptivity. In this study, we will investigate whether miR-135a/b influences the endometrial receptivity by regulating HOXA 10 and its target genes of integrin β3, EMX2 as well as PCAF. Meanwhile we will identify the possible signal pathways that are involved in up-regulation of miR-135a/b by high estradiol and progesterone levels. Our study will have important theoretical and clinical significance to improve the pregnancy rate in IVF.

子宫内膜容受性是妊娠建立的关键因素，体外授精（in vitro fetilization，IVF）促排卵过程中，超生理水平的雌孕激素可能影响子宫内膜容受性，其机制不清。我们前期大样本临床研究表明，IVF高孕或伴高雌激素环境导致妊娠率下降，但胚胎质量不受影响，推测子宫内膜容受性下降，同时患者着床窗口期子宫内膜miR-135a/b表达升高。通过生物信息学分析，我们发现miR-135a/b的一个潜在靶基因是HOXA10。有趣的是，以前的研究证明HOXA10及其下游靶基因整合素β3、EMX2及PCAF在构建子宫内膜容受性中发挥重要作用。因此，在本项目中，我们将研究miR-135a/b是否通过作用于HOXA10及其下游靶基因整合素β3、EMX2及PCAF调控IVF子宫内膜容受性。同时，我们将探讨高雌孕激素环境调控miR-135a/b的可能信号通路。这些研究对提高IVF妊娠率有重要理论和临床意义。

背景：辅助生殖治疗过程中，hCG日孕酮升高的患者，有着较低的着床率，我们的研究通过高孕酮环境下评估miR-135a是否通过结合HOXA10调节ITGβ3和EMX2的表达来影响胚胎着床过程。.方法：测定常规IVF治疗中，hCG日孕酮升高的患者子宫内膜组织中miR-135a、HOXA10、ITGβ3和EMX2的表达，对照为同样条件下，孕酮未升高的组织样本。利用Ishikawa细胞，采用5个梯度孕酮浓度，测定不同孕酮浓度下，以上4个基因的表达情况。并验证miR-135a对HOXA10的调控，以及HOXA10对内膜容受性关键基因ITGβ3和EMX2的表达控制。.结果：在体内，高孕酮水平会促进miR-135a的表达，而且，miR-135a可以结合HOXA10 mRNA的3’-UTR，抑制HOXA10的表达，而HOXA10的降低会在促进EMX2表达的同时，抑制ITGβ3的产生。在体外水平，随着孕酮浓度的升高，miR-135a和HOXA10有着反向趋势，即随着孕酮浓度的升高，miR-135a表达先下降后上升，而HOXA10的表达则先上升后下降。而HOXA10对于ITGβ3和EMX2的调控也有着同样的规律。表明HOXA10对于ITGβ3有着同向调控，对EMX2则相反。.结论：hCG日孕酮升高会导致种植率下降，其主要原因可能是高孕酮环境破坏了子宫内膜容受性，子宫内膜容受性的关键因子包括ITGβ3和EMX2，而HOXA10被证明是他们的调控因子。高孕酮水平会影响miR-135a的表达，而miR-135a会抑制HOXA10的基因表达，从而影响子宫内膜容受性。