Disruption of Pluripotency by Dioxin Exposure

总结 植入前胚胎易受母体环境的影响。暴露于环境 在这段时间内，有毒物质可能会严重损害发育程序，导致胎儿受损。 生长、出生缺陷和终身疾病。因此，迫切需要了解 早期发育期间的环境暴露会影响胚胎发生和成年期疾病。长期 这项研究的目的是确定环境暴露引发的机制，这些机制破坏了 发展方案。这些研究的目的是确定 二恶英是由于胚泡内细胞团（ICM）多能性丧失所致。我们建议 首要假设是芳香烃受体（AHR）-细胞内二恶英受体介导 二恶英的毒性是通过破坏胚胎植入前控制多能性的基因的调节来实现的 胚胎发生我们认为，了解ICM多能性的变化如何与基因组相关， 广泛的染色质相互作用将揭示潜在的发育毒性的机制， 环境暴露。我们会致力达致以下的具体目标：（一）确定二恶英 暴露破坏AHR在ICM多能性调节中的内源性功能;以及，（2）定义 AHR信号失调导致的多能性相互作用体的变化。这些目标考验着 二恶英暴露破坏AHR和核心之间的内源性相互作用的工作假设 在ICM中，多能性因子0CT 4与细胞内多能性因子0CT 4相互作用，并修饰0CT 4相互作用组，导致ICM中多能性的丧失。在 具体目标1，将确定每一种细胞对ICM或滋养层谱系的贡献， 两个全能的2-细胞期卵裂球，受到低剂量的2，3，7，8-四氯二苯并-对-二恶英（TCDD） exposure.在具体目标2中，将使用HiChIP深度测序（一种新的测序方法）研究OCT 4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，在ICM细胞中， 植入前囊胚暴露于TCDD。我们希望能了解 二恶英暴露导致发育损伤的机制。这项工作是创新的 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作用， 环境暴露造成的网络。我们的体内模型将使我们更好地理解 二恶英的发育毒性机制，使预防和干预成为可能 处理胚胎环境损伤的方法。这项工作的预期成果是 建立多能性丧失和全基因组染色质相互作用变化之间的联系， 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.