Environmental Modulation of Epigenetic Reprogramming in Pluripotent Cells

描述(由申请人提供)：表观遗传重编程，特别是DNA甲基化的重置，是植入前发育和胎儿胚系中的关键事件。母亲饮食的改变或暴露在环境污染物中会扰乱胎儿的表观遗传重新编程，并导致妊娠失败、发育障碍或成人发病，但其潜在的分子机制仍不清楚。重要的是要填补这一空白，以便为产妇饮食和环境毒素暴露制定知情的安全标准，并了解成人发病的表观遗传学基础。研究人员的长期目标是了解胚胎发育的表观遗传调节。这项应用的目的是确定维生素C在胚胎表观遗传重编程中的作用。人类完全依赖饮食中的维生素C，这是几个生理过程中必不可少的。我们实验室的最新发现表明，维生素C在表观遗传重编程的直接调节中具有新的作用，特别是在多能干细胞中DNA去甲基化和生殖系基因的激活方面。这项提议将检验这一创新假设，即维生素C是多能干细胞和胎儿生殖系表观遗传重新编程的关键环境调节因子。其具体目的是：1)确定维生素C在表观遗传重编程中的作用机制。研究人员将测试维生素C作为Tet酶的潜在辅助因素在生殖系基因启动子产生5-羟甲基胞嘧啶中的作用；2)确定暴露在多能干细胞中的维生素C的功能后果。将评估维生素C在调节体外多能干细胞特有的功能中的作用；以及3)挑战维生素C介导的表观遗传重新编程的易感性窗口(WOS)。研究人员将使用一种经过验证的维生素C缺乏症小鼠模型来确定在体内发生表观遗传重编程的阶段WOS到维生素C的比例。这项研究有望为妊娠期间表观遗传重编程的饮食和环境调节提供基本的新见解，在毒理学、母婴医学、生殖生物学和癌症方面具有重大影响。

DESCRIPTION (provided by applicant): Epigenetic reprogramming, and specifically the resetting of DNA methylation, is a key event during preimplantation development and in the fetal germline. Changes in the maternal diet or exposure to environmental contaminants can disrupt fetal epigenetic reprogramming and lead to pregnancy failure, developmental disorders or adult-onset disease, but the underlying molecular mechanisms remain unknown. It is important to fill this gap in order to develop informed safety standards for maternal diet and exposure to environmental toxins, and understand the epigenetic basis of adult-onset disease. The long-term goal of the investigators' research is to understand the epigenetic regulation of embryonic development. The objective of this application is to define the role of Vitamin C in epigenetic reprogramming in the embryo. Humans rely entirely on their diet for Vitamin C, which is essential for several physiological processes. Recent findings from our lab indicate that Vitamin C has a novel role in the direct regulation of epigenetic reprogramming, and specifically in DNA de-methylation and activation of germline genes in pluripotent stem cells. This proposal will test the innovative hypothesis that Vitamin C is a critical environmental regulator of epigenetic reprogramming in pluripotent stem cells and the fetal germline. The specific aims are: 1) to determine the mechanism of action of Vitamin C in epigenetic reprogramming. The investigators will test the role of Vitamin C as a potential co-factor of Tet enzymes in the generation of 5-hydroxymethyl-Cytosine at the promoters of germline genes; 2) to determine the functional consequences of exposure to Vitamin C in pluripotent stem cells. The role of Vitamin C will be assessed in the regulation of functions specific to pluripotent stem cells in vitro; and 3) to defie the Windows of Susceptibility (WOS) of Vitamin C-mediated epigenetic reprogramming. The investigators will use a validated mouse model of Vitamin C deficiency to determine the WOS to Vitamin C during the stages when epigenetic reprogramming occurs in vivo. This research is expected to provide fundamental new insights into the dietary and environmental modulation of epigenetic reprogramming during gestation, with significant impact in toxicology, maternal-fetal medicine, reproductive biology and cancer.