Hoxa11调控β-catenin的分子机制在胚胎着床中作用的研究

Hoxa11 gene plays an important role in uterus development and embryo implantation. The development of endometrial stromal cells, decidual cells and glandular cells were deficient in Hoxa11 knockout mouse.Studies showed that the postnatal loss of Hoxa11 expression in endometrial stroma was observed in Wnt7a knockout mouse, and the mice with conditional deletion of β-catenin in uteri exhibited decidualization defects, suggesting that Wnt/β-catenin is involved in regulation of Hoxa11 in the embryo implantation. Our precious study showed that there was positive correlation between the expression of Hoxa11 and β-catenin in murine uterus in all the ovarian hyperstimulation groups. Overexpression of Hoxa11 could increase the β-catenin expression in endometrial stroma of mice during peri-implantation period. We speculate that Hoxa11 expression could be in favor of embryonic implantation by regulating the Wnt/β-catenin signal pathway. This study aims to further explore the molecular mechanisms of Hoxa11 in regulation of decidualization and to figure out the regulating network between Hoxa11 and Wnt/β-catenin, which implies important scientific and clinical significance in searching for new theropy methods to increase the embryonic implantaion rate .

Hoxa11基因在子宫发育和胚胎着床机制中发挥重要作用，敲除Hoxa11基因的小鼠，子宫内膜基质细胞、蜕膜发育缺陷。研究表明，Wnt7a基因敲除的小鼠子宫基质细胞Hoxa11表达缺失，而敲除β-catenin基因的小鼠也会发生蜕膜化的缺陷，表明Wnt/β-catenin信号通路分子可能参与Hoxa11介导的子宫发育和胚胎着床机制。前期研究中，我们首次发现超促排卵小鼠子宫围着床期Hoxa11和β-catenin的表达明显下降，通过体内转染上调小鼠子宫内膜Hoxa11表达可使基质细胞β-catenin表达显著增强，推测Hoxa11调控Wnt/β-catenin信号通路可能对提高胚胎着床率具有重要科学价值。本课题将深入研究Hoxa11调控基质细胞蜕膜化的分子机制及其与Wnt/β-catenin信号通路的关系，探索新的提高胚胎着床率的治疗靶点，对提高优质胚胎着床成功率具有重要的科学和临床意义。

胚胎着床失败是辅助生殖技术中难以攻克的难题。研究表明Hoxa11及Wnt/β-catenin信号通路在子宫的发育，调控基质细胞蜕膜化及胚胎着床方面均发挥重要的作用。我们前期研究发现，围着床期小鼠子宫内膜Hoxa11可能直接或间接调节β-catenin的表达。但是Hoxa11调控子宫内膜蜕膜化的具体分子机制尚不清楚。本课题将在前一研究的基础上进一步探索Hoxa11调控子宫内膜蜕膜化的分子机制，以及和Wnt/β-catenin信号通路的相互调节关系。免疫组织化学技术检测孕1-8天小鼠子宫内膜中Hoxa11 和 β-catenin的表达情况，发现Hoxa11及β-catenin在孕早期小鼠子宫内膜的基质细胞中表达随孕天数增加而升高，向子宫角注入小鼠Hoxa11上调/下调质粒后，发现围着床期小鼠子宫内膜中β-catenin随Hoxa11的表达升高或下降而随之相应变化。通过shRNA 技术下调人蜕膜细胞及蜕膜化THESC细胞系中Hoxa11的表达，发现β-catenin，wnt5，MMP7表达随之下降。这说明β-catenin参与Hoxa11对蜕膜化的调控过程。人蜕膜细胞转染Hoxa11 shRNA后，通过基因芯片技术，筛选出上调基因330个，下调基因359个。其中差异最为明显的为IL8，随后进一步鉴定证实IL-8随Hoxa11下调表达大幅度增加，说明IL-8可能为Hoxa11的下游靶分子，为改善子宫内膜容受性提供了新靶点。