Zhong Jianxiang, Xu Cheng, Reece E Albert, Yang Peixin
Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD.
Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD.
Am J Obstet Gynecol. 2016 Sep;215(3):368.e1-368.e10. doi: 10.1016/j.ajog.2016.03.009. Epub 2016 Mar 12.
Maternal diabetes increases the risk of neural tube defects in offspring. Our previous study demonstrated that the green tea polyphenol, Epigallocatechin gallate, inhibits high glucose-induced neural tube defects in cultured embryos. However, the therapeutic effect of Epigallocatechin gallate on maternal diabetes-induced neural tube defects is still unclear.
We aimed to examine whether Epigallocatechin gallate treatment can reduce maternal diabetes-induced DNA methylation and neural tube defects.
Nondiabetic and diabetic pregnant mice at embryonic day 5.5 were given drinking water with or without 1 or 10 μM Epigallocatechin gallate. At embryonic day 8.75, embryos were dissected from the visceral yolk sac for the measurement of the levels and activity of DNA methyltransferases, the levels of global DNA methylation, and methylation in the CpG islands of neural tube closure essential gene promoters. embryonic day 10.5 embryos were examined for neural tube defect incidence.
Epigallocatechin gallate treatment did not affect embryonic development because embryos from nondiabetic dams treated with Epigallocatechin gallate did not exhibit any neural tube defects. Treatment with 1 μM Epigallocatechin gallate did not reduce maternal diabetes-induced neural tube defects significantly. Embryos from diabetic dams treated with 10 μM Epigallocatechin gallate had a significantly lower neural tube defect incidence compared with that of embryos without Epigallocatechin gallate treatment. Epigallocatechin gallate reduced neural tube defect rates from 29.5% to 2%, an incidence that is comparable with that of embryos from nondiabetic dams. Ten micromoles of Epigallocatechin gallate treatment blocked maternal diabetes-increased DNA methyltransferases 3a and 3b expression and their activities, leading to the suppression of global DNA hypermethylation. Additionally, 10 μM Epigallocatechin gallate abrogated maternal diabetes-increased DNA methylation in the CpG islands of neural tube closure essential genes, including Grhl3, Pax3, and Tulp3.
Epigallocatechin gallate reduces maternal diabetes-induced neural tube defects formation and blocks the enhanced expression and activity of DNA methyltransferases, leading to the suppression of DNA hypermethylation and the restoration of neural tube closure essential gene expression. These observations suggest that Epigallocatechin gallate supplements could mitigate the teratogenic effects of hyperglycemia on the developing embryo and prevent diabetes-induced neural tube defects.
母亲患糖尿病会增加后代患神经管缺陷的风险。我们之前的研究表明，绿茶多酚表没食子儿茶素没食子酸酯可抑制培养胚胎中高糖诱导的神经管缺陷。然而，表没食子儿茶素没食子酸酯对母亲糖尿病诱导的神经管缺陷的治疗效果仍不清楚。
我们旨在研究表没食子儿茶素没食子酸酯治疗是否能减少母亲糖尿病诱导的DNA甲基化和神经管缺陷。
在胚胎第5.5天，给非糖尿病和糖尿病怀孕小鼠饮用含或不含1或10 μM表没食子儿茶素没食子酸酯的水。在胚胎第8.75天，从内脏卵黄囊中取出胚胎，用于测量DNA甲基转移酶的水平和活性、整体DNA甲基化水平以及神经管闭合关键基因启动子的CpG岛中的甲基化情况。检查胚胎第10.5天的胚胎的神经管缺陷发生率。
表没食子儿茶素没食子酸酯治疗不影响胚胎发育，因为用表没食子儿茶素没食子酸酯治疗的非糖尿病母鼠的胚胎未表现出任何神经管缺陷。用1 μM表没食子儿茶素没食子酸酯治疗并未显著降低母亲糖尿病诱导的神经管缺陷。与未用表没食子儿茶素没食子酸酯治疗的胚胎相比，用10 μM表没食子儿茶素没食子酸酯治疗的糖尿病母鼠的胚胎的神经管缺陷发生率显著降低。表没食子儿茶素没食子酸酯将神经管缺陷率从29.5%降至2%，这一发生率与非糖尿病母鼠的胚胎相当。10 μmol表没食子儿茶素没食子酸酯治疗可阻断母亲糖尿病增加的DNA甲基转移酶3a和3b的表达及其活性，导致整体DNA高甲基化受到抑制。此外，10 μM表没食子儿茶素没食子酸酯消除了母亲糖尿病增加的神经管闭合关键基因（包括Grhl3、Pax3和Tulp3）的CpG岛中的DNA甲基化。
表没食子儿茶素没食子酸酯可减少母亲糖尿病诱导的神经管缺陷形成，并阻断DNA甲基转移酶的增强表达和活性，导致DNA高甲基化受到抑制以及神经管闭合关键基因表达恢复。这些观察结果表明，表没食子儿茶素没食子酸酯补充剂可减轻高血糖对发育中胚胎的致畸作用，并预防糖尿病诱导的神经管缺陷。
