LncRNA-MALAT1作为ceRNA调控胎盘血管形成的机制研究

A favorable placental vascular development has a direct impact on pregnant outcomes. Endothelial progenitor cells（EPCs）have the characteristics of stem cells and play a key role in the process of angiogenesis. Long non-coding RNA (lncRNA) controls miRNAs available for binding with their target mRNAs, thus raising the repression of these mRNAs, acting as competing endogenous RNA (ceRNA). Studies have shown that the expression of lncRNA MALAT1 is reduced in preeclampsia placenta and over expression of MALAT1 can significantly promote the proliferation of EPCs. Bioinformatics analysis reveals that MALAT1 may combine with miRNA-21, while the latter has been confirmed regulating placental vascular development by targeting BCL-2. Therefore, we infer that MALAT1 can relieve the inhibition effect of target genes by competitive combination with miRNA-21, thus promote placental vascular development. The binding between MALAT1 and miRNA-21 will be verified using dual luciferase and RNA binding protein immunoprecipitation assay. And then we plan to regulate the expression of MALAT1 to verify this mechanism is involved in regulating placental vascular development in vitro and in vivo. Finally we will confirm MALAT1 plays a key role in placental vascular development as ceRNA. And it may provide new way for the diagnosis and treatment of placental vascular diseases.

胎盘血管的良好形成与妊娠结局密切相关。血管内皮祖细胞（EPCs）具有干细胞特性，在血管生成过程中起关键作用。研究证实长链非编码RNA（lncRNA）可作为竞争性内源RNA（ceRNA）抑制miRNA与靶mRNA结合而上调其表达。前期我们发现lncRNA MALAT1在子痫前期胎盘组织中表达降低，上调其表达可显著促进EPCs增殖。生物信息学预测MALAT1可能与miRNA-21结合，而后者已被证实通过靶向BCL-2等调控胎盘血管形成，据此我们推测MALAT1通过竞争性结合miRNA-21，解除其对靶基因的抑制，促进胎盘血管形成。研究拟从EPCs入手，双荧光素酶和RNA结合蛋白免疫沉淀检测MALAT1竞争性结合miRNA-21；调控MALAT1表达，体外及体内验证这一机制参与调控胎盘血管形成。最终阐明MALAT1作为ceRNA在胎盘血管形成中的关键作用，为胎盘血管相关疾病的诊治提供新思路。

胎盘富含血管，是母体和胎儿进行物质交换的主要器官，对妊娠的进展和结局意义重大。胎盘血管发育障碍使得胎盘血流灌注受损、胎儿缺血缺氧，导致临床上常见的一系列胎盘血管相关疾病，严重影响胎儿的生长发育，降低新生儿质量。若能有效促进胎盘血管形成，对改善胎盘血流灌注，治疗胎盘血管相关疾病，提高围产儿预后具有重要意义。内皮祖细胞（EPCs）具有干细胞特性，增殖能力更强，且能直接反映血管受损程度，在胎盘血管形成过程中发挥重要作用。妊娠中EPCs数量和功能不足可引起内皮细胞代谢障碍，导致广泛内皮功能受损及子痫前期的发生。本课题组通过qRT-PCR检测，发现MALAT1在子痫前期胎盘组织中表达降低；通过上调其表达，EPCs的增殖功能显著增强。因此我们初步推测：MALAT1可能通过调节EPCs的功能，促进胎盘血管生成。采用MALAT1 smart silencer转染后，EPCs的增殖、迁移、分化及管腔形成能力均显著降低。提示MALAT1可能参与了胎盘血管形成及子痫前期的发生。进一步我们通过双荧光素酶报告基因检测和RIP实验验证MALAT1与miRNA-21靶向结合，且作为ceRNA调控miRNA-21靶基因BCL-2的表达水平。后续我们通过体内外功能实验进一步验证了MALAT1-miRNA-21-BCL-2通路在子痫前期发病机制中的作用，最终证实MALAT1作为ceRNA在胎盘血管形成中的关键作用。本研究首次将两种非编码RNA的功能结合，初步探讨以lncRNA为基石的ceRNA网络体系在胎盘血管形成中的作用，研究结果为最终阐明胎盘血管形成机制和寻找新的治疗靶点具有重要意义。