Up-Regulated Expression and Aberrant DNA Methylation of LEP and SH3PXD2A in Pre-Eclampsia

The primary mechanism underlying pre-eclampsia (PE) remains one of the most burning problems in the obstetrics and gynecology. In this study, we performed an expression profiling screen and detected 1312 genes that were differentially expressed (p1.5) in PE placentas, including LEP and SH3PXD2A. After validating the microarray results, we conducted the quantitative methylation analysis of LEP and SH3PXD2A in preeclamptic (n = 16) versus normal placentas (n = 16). Our results showed that many CpG sites close to the transcriptional start site (TSS) of LEP gene were hypomethylated in placentas from pregnancies with PE compared with those of in controls, including the TSS position (p = 0.001), the binding sites of Sp1 (p = 1.57×10−4), LP1 (p = 0.023) and CEBPα (p = 0.031). Luciferase reporter analysis confirmed the aberrant methylation of LEP promoter and CEBPα co-transfection had a role in the regulation of gene expression. Our results indicated the aberrant LEP promoter methylation was involved in the development of PE. We did not find a significant methylation differences between groups in the promoter region of SH3PXD2A, however, a CGI region in the gene body (CGI34) presented a higher methylation in preeclamptic placentas (p = 1.57×10−4), which might promote the efficiency of gene transcription. We speculated that SH3PXD2A may take part in the pathogenesis of PE through its role in the regulation of trophoblast cell invasion in the period of placenta formation.子痫前期（pre-eclampsia, PE）的核心发病机制仍是妇产科学领域最亟待解决的热点难题之一。本研究通过表达谱筛选，在子痫前期胎盘组织中鉴定出1312个差异表达基因（p=1.5），其中包含LEP与SH3PXD2A。在验证微阵列实验结果后，我们针对16例子痫前期胎盘组织与16例正常胎盘组织，开展了LEP与SH3PXD2A的定量甲基化分析。研究结果显示，相较于对照组，子痫前期妊娠胎盘组织中LEP基因转录起始位点（transcriptional start site, TSS）邻近的多个CpG位点呈现低甲基化状态，具体包括TSS位点本身（p=0.001）、Sp1结合位点（p=1.57×10^-4）、LP1结合位点（p=0.023）以及CEBPα结合位点（p=0.031）。荧光素酶报告基因实验证实，LEP启动子的异常甲基化与CEBPα共转染均可对基因表达产生调控作用。本研究结果表明，LEP启动子的异常甲基化参与了子痫前期的发生发展过程。我们未在SH3PXD2A的启动子区域观察到组间存在显著甲基化差异，但该基因本体中的CGI区域（CGI34）在子痫前期胎盘组织中呈现更高的甲基化水平（p=1.57×10^-4），该变化或可提升基因的转录效率。我们推测，SH3PXD2A可能通过调控胎盘形成阶段的滋养层细胞侵袭过程，参与子痫前期的发病机制。