Disruption of Pluripotency by Dioxin Exposure

摘要 植入前的胚胎很容易受到母体环境的影响。暴露在环境中 在这段时间内，毒物可能会严重损害发育程序，导致胎儿受损 生长、出生缺陷和终生疾病。因此，迫切需要了解 发育早期的环境暴露会影响胚胎发育和成人疾病。长期的 这项研究的目标是确定环境暴露引发的破坏 发展计划。这些研究的目的是确定 二恶英是胚泡内细胞团(ICM)丧失多能性的结果。我们建议 最重要的假设是芳烃受体(AHR)-细胞内的二恶英受体-介导 二恶英在植入前通过破坏控制多能性的基因的调节而产生的毒性 胚胎发生。我们认为，了解ICM多能性的变化如何与基因组- 广泛的染色质相互作用将有助于阐明其发育毒性的潜在机制 暴露在环境中。我们将针对以下具体目标：(1)确定二恶英是否 暴露扰乱AHR在调节ICM多能性中的内源性功能；以及，(2)定义 去调节AHR信号导致的多能性相互作用组的变化。这些目标考验着 工作假说：接触二恶英扰乱了AHR和核心之间的内源性相互作用 多能性因子OCT4并修饰OCT4相互作用组，导致ICM失去多能性。在……里面 具体目标1，将确定对ICM或滋养层谱系的贡献 小剂量2，3，7，8-四氯二苯并-对二恶英(TCDD)诱导的两个全能2-细胞期卵裂球 曝光。在特定目标2中，将使用一种新型的HiChIP深度测序来研究OCT4相互作用组 研究以蛋白质为中心的三维(3D)染色质相互作用的方法 植入前胚泡暴露于TCDD。我们希望加深对基本原理的理解 二恶英暴露所致发育损伤的机制(S)。这项工作具有创新性 因为它将使用先进的3D染色质结构方法来研究多能性的毒性效应 因环境暴露而形成的网络。我们的活体模型将使我们更好地理解 二恶英发育毒性的机制，为预防和干预提供可能 处理胚胎环境损伤的方法。这项工作的预期结果是 在多能性丧失和全基因组染色质相互作用变化之间建立联系，这将 为确定这些变化如何影响子宫内胚胎发育提供了基础。

Summary Preimplantation embryos are vulnerable to the maternal environment. Exposure to environmental toxicants during this time may substantially damage the developmental program, leading to impaired fetal growth, birth defects, and life-long disease. Hence, there is a critical need to understand how the outcome of environmental exposures during early development affects embryogenesis and adult disease. The long-term goal of this research is to identify the mechanisms triggered by environmental exposure that disrupt the developmental programs. The objective of these studies is to determine whether the developmental toxicity of dioxins results from loss of pluripotency in the inner cell mass (ICM) of blastocysts. We propose the overarching hypothesis that the aryl hydrocarbon receptor (AHR) —the intracellular dioxin receptor—mediates the toxicity of dioxin by disrupting the regulation of the genes that control pluripotency during preimplantation embryogenesis. We believe that understanding how changes in ICM pluripotency are associated with genome- wide chromatin interactions will shed light on the mechanisms underlying the developmental toxicity of environmental exposures. We will address the following specific aims: (1) to determine whether dioxin exposure disrupts endogenous functions of the AHR in the regulation of ICM pluripotency; and, (2) to define changes in the pluripotency interactome resulting from deregulation of AHR signaling. These aims test the working hypothesis that dioxin exposure disrupts the endogenous interplay between the AHR and the core pluripotency factor OCT4 and modifies the OCT4 interactome, leading to loss of pluripotency in the ICM. In specific aim 1, the contribution to the ICM or to the trophoblast lineage will be determined for each one of the two totipotent 2-cell-stage blastomeres, subjected to low dose 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure. In specific aim 2, the OCT4 interactome will be investigated using HiChIP deep sequencing, a novel approach to study protein-centered three-dimensional (3D) chromatin interactions, in ICM cells of preimplantation blastocysts exposed to TCDD. We hope to develop an understanding of the fundamental mechanism(s) responsible for the developmental injuries caused by dioxin exposure. This work is innovative because it will use an advanced 3D chromatin structure approach to study toxic effects in pluripotency networks resulting from environmental exposure. Our in vivo model will lead to a better comprehension of the mechanisms of developmental toxicity of dioxins, making it possible to arrive at prevention and intervention approaches to deal with embryonic environmental injury. The expected outcome of this work is the establishment of a link between pluripotency loss and genome-wide chromatin interaction changes, which will provide the foundation to determine how these changes influence the in utero embryonic development.