胎盘HIF-1α调控miR210/THSD7A在单合子双胎选择性宫内生长受限中的作用的研究

The DNA sequence and intrauterine environment between zygotic twins are almost the same. Selective intrauterine growth restriction (sIUGR) is one of the most severe complications among zygotic twins with adverse outcome, but the mechanism of which is still unclear. We have found that the smaller twin of sIUGR shared less placenta and had sparser vasculature compared with the larger twin. Our previous study in which we investigated the different expressions of miRNA in the placenta of sIUGR showed that miR210 was much higher expressed in the placenta of the small fetuses than that of the lager ones. We infer that the different expressions of miR210 play an important role in sIUGR，but what is the mechanism in this process? Our further study showed that miR210 is induced by hypoxia induced factor 1α (HIF-1α) under a circumstance of hypoxia. We have demonstrated that THSD7A, one of the predicted target genes of miR210, was expressed abundantly in placenta. Previous studies had showed that THSD7A may have an impact on the development of trophoblasts and vasculature. Thus, we presume that the up-regulation of miR210 induced by HIF-1α inhibits the expression of THSD7A, leading to the dysplasias of trophoblasts and vasculature. The dysfunction of placenta results in sIUGR. The purpose of this project is to investigate the mechanism of miR210 and THSD7A regulated by HIF-1α in placenta of sIUGR and try to provide a new insight for the pathogenesis and prenatal treatment of complicated twins and placenta-derived diseases.

单合子双胎具有相同的DNA序列及宫内环境，选择性宫内生长受限（sIUGR）是此类双胎常见的严重并发症，其发病的分子机制未明。我们已证实sIUGR双胎中，生长受限胎所属胎盘份额小、胎盘血管密度及分支减少。前期通过测序技术发现小胎胎盘中miR210表达显著高于大胎。胎盘miR210差异表达与sIUGR发病的关系及其机制是什么？在细胞缺氧模型中我们发现HIF-1α诱导miR210上调，其预测的靶基因THSD7A在胎盘滋养细胞表达丰富。推测THSD7A可能与滋养细胞侵袭增殖、血管形成相关。据此假设：双胎之一胎对应的胎盘局部缺氧时HIF-1α调控miR210表达升高，继而使THSD7A下调，影响滋养细胞功能，造成胎盘绒毛和血管发育障碍，导致一胎发育滞后从而发生sIUGR。本项目拟探讨胎盘HIF-1α调控miR210/THSD7A在sIUGR发病中的作用机制，进一步为胎盘源性疾病的防治提供科学依据。

双胎选择性宫内生长受限(sIUGR)是单绒毛膜双羊膜囊双胎(MCDA)的特有并发症，目前研究认为两胎胎盘份额不均是sIUGR的主要病理机制。我们前期通过small RNA-Seq技术筛选sIUGR的大胎和小胎胎盘份额中差异表达的miRNA，发现miR-210-3p在小胎胎盘中的表达高于大胎且是两胎之间差异最为显著的miRNA之一。目前研究发现并验证的miR-210靶基因约有40个，但尚无与sIUGR发病相关的靶基因的报道。因此，本研究拟以具有高度一致的遗传背景及宫内环境的单合子MCDA双胎作为研究对象，通过检测miR-210-3p在sIUGR与正常妊娠胎盘中的表达特征，探讨胎盘miR-210-3p表达与sIUGR的关系，在体外滋养细胞系HTR8/SVneo中研究miR-210-3p对滋养细胞功能的影响，并进一步利用转录组测序技术筛选和鉴定miR-210-3p靶基因，结合体外缺氧模型，从表观遗传学及分子细胞学水平初步探讨miR-210-3p及其下游靶基因对sIUGR发生发展的可能调控机制。研究结果显示，胎盘miR-210-3p高表达与sIUGR发病有关，FGF1是miR-210-3p的直接调控靶基因，高表达miR-210-3p通过抑制FGF1表达从而抑制滋养细胞增殖、侵袭能力，缺氧条件下通过HIF-1a/miR-210-3p/FGF1信号通路抑制滋养细胞功能，与小胎胎盘份额发育不良及sIUGR发生有关。该研究有助于从分子水平理解sIUGR的发病机制，有助于今后对疾病的早期诊断和改善预后。