Gene-environment interactions in epithelial morphogenesis

项目总结/摘要 二恶英类化学物质（DLC）是全球环境污染物，对人类健康构成重大威胁。 人类人们普遍认为，基因构成是暴露于疾病风险的主要决定因素，但 使个体易患疾病的实际基因-环境机制知之甚少。我们 已经开发了一种小鼠模型来研究使发育组织对二恶英敏感的基因突变 毒性该模型基于胚胎眼睑闭合，这是所有哺乳动物中保守的发育过程。 眼睑闭合是发生在胚胎发育后期的主要形态发生事件，由眼睑的前向运动驱动。 眼睑上皮细胞导致相对眼睑的融合。眼睑闭合失败不会危及生命 但在新生儿中导致出生时睁眼（EOB）表型。EOB表型很容易发现， 因此在大量的遗传突变株中发现。多年来，EOB小鼠作为 是阐明上皮形态发生的遗传网络和信号机制的有力工具。 在此模型的基础上，我们确定了MAP 3 K1-JNK信号级联在眼睑的调节中的作用。 结束我们最近应用该系统研究了环境化学物质的遗传易感性 毒性，并表明Map 3 k1基因杂合性和宫内二恶英暴露的组合， 眼睑闭合，而这两种情况都没有单独的有害影响。这些观察结果表明，眼睑 闭合缺陷可以是由基因-环境（GxE）相互作用引起的多因素疾病。当前 该提案将在三个特定目标中通过检验假设来研究GxE相互作用的机制 遗传和环境压力集中在抑制MAP 3 K1-JNK通路上， 上皮形态发生目标1将确定二恶英信号和MAP 3 K1之间的分子联系。 JNK通路。在初步研究结果的指导下，我们将测试EGFR通路是否介导串扰 在眼睑发育过程中的信号。结果将定义一种新的机制，其中遗传和 环境因素靶向单独的信号传导途径，但是途径的串扰导致不利的信号传导。 结果。目的2将确定新的遗传成分的MAP 3 K1途径二恶英毒性。结果将 导致对易受化学毒性影响的遗传条件的机械理解。目标3将桥梁 利用MAP 3 K1的识别，缩小基础研究与转化研究之间的差距 先天性眼结构异常患者的杂合性。我们将使用患者特异性诱导 多能干细胞（iPSC），以检查在体外分化过程中二恶英处理是否会导致 MAP 3 K1信号转导的失活和上皮细胞迁移受损，这是与 眼睑闭合不良。结果将使我们更接近于将小鼠的机制发现转化为 了解人类疾病。本项目中提出的研究将提供关键的见解， 的GxE相互作用和实验范式，研究多因素病因的出生缺陷。

Project Summary/Abstract The dioxin-like chemicals (DLCs) are global environmental pollutants that pose a significant health threat to humans. It is widely believed that the genetic make-up is a major determinant of disease risk from exposure, but the actual gene-environment mechanisms that predispose individuals to disease are poorly understood. We have developed a mouse model to investigate gene mutations that sensitize developmental tissues to dioxin toxicity. The model is based on embryonic eyelid closure, a developmental process conserved in all mammals. Eyelid closure is a major morphogenetic event occurring in late embryogenesis, driven by forward movement of the eyelid epithelial cells leading to fusion of the opposing eyelids. Failure of eyelid closure is not life threatening but results in an eye open at birth (EOB) phenotype in the newborns. The EOB phenotype is easy to spot, and consequently is found in a large number of genetic mutant strains. Over the years, the EOB mice serve as a powerful tool to elucidate the genetic network and signaling mechanisms underlying epithelium morphogenesis. Building on this model, we have identified the MAP3K1-JNK signaling cascades in the regulation of eyelid closure. We recently applied this system to investigate the genetic susceptibility to environmental chemical toxicity, and showed that the combination of Map3k1 gene heterozygosity and in utero dioxin exposure blocks eyelid closure whereas neither condition alone has a detrimental effect. These observations suggest that eyelid closure defect can be a multifactorial disorder resulting from gene-environment (GxE) interactions. The current proposal will investigate in three Specific Aims the mechanisms of GxE interactions by testing the hypothesis that genetic and environmental stresses converge on repression of the MAP3K1-JNK pathway to disrupt epithelial morphogenesis. Aim 1 will determine the molecular link between the dioxin signals and the MAP3K1- JNK pathways. Guided by preliminary findings, we will test whether the EGFR pathway mediates the crosstalk between these signals in eyelid development. Results will define a novel mechanism where the genetic and environmental factors target separate signaling pathways, but the crosstalk of the pathways leads to adverse outcomes. Aim 2 will identify novel genetic components of the MAP3K1 pathway in dioxin toxicity. Results will lead to a mechanistic understanding of the genetic conditions susceptible to chemical toxicity. Aim 3 will bridge the gap between basic and translational research by taking advantage of the identification of MAP3K1 heterozygosity in a patient with congenital eye structural abnormalities. We will use patient-specific induced pluripotent stem cells (iPSCs) to examine whether dioxin treatment during in vitro differentiation leads to inactivation of MAP3K1 signaling and impaired epithelial cell migration, which are biological endpoints linked to defective eyelid closure. Results will bring us a step closer to translate mechanistic discoveries in mice to understanding human diseases. Studies proposed in this project will provide critical insights into the mechanisms of GxE interactions and an experimental paradigm to study multifactorial etiology underlying birth defects.