Ma Min, Zhou Qiong-Jie, Xiong Yu, Li Bin, Li Xiao-Tian
Department of Obstetrics, Obstetrics and Gynecology Hospital of Fudan UniversityShanghai 200011, China.
Department of Obstetrics and Gynecology, Medical College of Yangzhou UniversityYangzhou 225000, Jiangsu, China.
Am J Transl Res. 2018 Jan 15;10(1):16-39. eCollection 2018.
Previous studies have demonstrated a dynamic epigenetic regulation of genes expression in placenta trophoblasts and a dynamic imbalance of DNA methylation and hydroxymethylation. Reduced IGF-1 has been observed in preeclampsia. This study was to investigate the interactive roles between IGF-1 and the global DNA methylation/hydroxymethylation, and the status of DNA methylation/hydroxymethylation and associated enzymes such as DNMTs and TETs in peeeclamptic placentas and hypoxic trophoblasts. It was found that IGF-1 was decreased in preeclamptic placentas and hypoxic trophoblasts when compared to the control group using immunohistochemisty, western blot, qRT-PCR and ELISA. Pyrophosphate sequencing showed IGF-1 promoter was significantly hypermethylated in preeclamptic placentas, which was responsible for reduced IGF-1 expression. Preeclamptic placentas and hypoxic trophoblasts were hypermethylated and hypohydroxymethylated accompanied by remarkably higher 5mC, DNMT1 and DNMT3b, and lower DNMT3a, 5hmC, TET1, TET2 and TET3 detected by immunohistochemisty, western blot, qRT-PCR and ELISA. Pearson's correlation confirmed a statistically significant negative correlation between IGF-1 and DNMT1. Furthermore, both treatment with 5-Aza-dc and DNMT1-siRNA significantly increased the expression of IGF-1 in HTR8 cells, indicating the potential mechanism of DNMT1-mediated DNA methylation in IGF-1 regulation. However, IGF-1 didn't change DNA methylation or hydroxymethylation. These findings suggest that preeclampsia is associated with hypermethylation of IGF-1 promoter mediated by DNMT1 and provide new insights into the diagnosis and treatment of preeclampsia.
先前的研究已经证明胎盘滋养层细胞中基因表达存在动态表观遗传调控，以及DNA甲基化和羟甲基化的动态失衡。子痫前期患者中已观察到胰岛素样生长因子-1（IGF-1）水平降低。本研究旨在探讨IGF-1与整体DNA甲基化/羟甲基化之间的相互作用，以及子痫前期胎盘和缺氧滋养层细胞中DNA甲基化/羟甲基化状态以及相关酶（如DNA甲基转移酶（DNMTs）和双加氧酶（TETs））的情况。通过免疫组织化学、蛋白质免疫印迹、定量逆转录聚合酶链反应（qRT-PCR）和酶联免疫吸附测定（ELISA）发现，与对照组相比，子痫前期胎盘和缺氧滋养层细胞中的IGF-1水平降低。焦磷酸测序显示，子痫前期胎盘的IGF-1启动子显著高甲基化，这导致了IGF-1表达降低。免疫组织化学、蛋白质免疫印迹、qRT-PCR和ELISA检测发现，子痫前期胎盘和缺氧滋养层细胞存在高甲基化和低羟甲基化，同时5-甲基胞嘧啶（5mC）、DNMT1和DNMT3b水平显著升高，而DNMT3a、5-羟甲基胞嘧啶（5hmC）、TET1、TET2和TET3水平降低。皮尔逊相关性分析证实IGF-1与DNMT1之间存在统计学上显著的负相关。此外，5-氮杂-2'-脱氧胞苷（5-Aza-dc）和DNMT1小干扰RNA（siRNA）处理均显著增加了HTR8细胞中IGF-1的表达，表明DNMT1介导的DNA甲基化在IGF-1调控中的潜在机制。然而，IGF-1并未改变DNA甲基化或羟甲基化。这些发现表明子痫前期与DNMT1介导的IGF-1启动子高甲基化有关，并为子痫前期的诊断和治疗提供了新的见解。
