Activation of Nrf2 during embryonic development: mechanisms and consequences

 描述(由申请人提供)：生命早期暴露于环境污染物可导致胰腺β细胞发育异常，这可能使个人易患糖尿病。许多不同的环境污染物共有的一种常见的毒性模式是产生活性氧物种(ROS)和氧化应激。ROS和细胞氧化还原电位在正常胚胎发育和细胞信号转导中起着重要作用。污染物暴露引起的这些过程的扰动可以改变细胞命运的决定，导致功能或结构的改变，只有在随后的压力或年龄下才会变得明显。然而，令人惊讶的是，人们对胚胎如何应对氧化应激，或毒物暴露对胰腺发育的影响知之甚少。这项研究的长期目标是了解胚胎如何对氧化应激做出反应，以及毒物暴露如何有助于糖尿病的发育起源。斑马鱼(Danio Rerio)是一种在体内研究脊椎动物胚胎发育的成熟、广泛和强大的模式生物。为了研究发育中氧化还原微环境的变化如何影响特定阶段的毒物敏感性和胰腺β细胞，我们将使用荧光氧化还原生物传感器、氧化还原成像和自动化、时间推移显微镜对暴露在环境污染中的透明转基因斑马鱼胚胎进行观察。该项目将重点关注与环境相关的、此前与糖尿病病因学有关的持久性毒物(多氯联苯、邻苯二甲酸盐和特氟龙表面活性剂全氟辛烷磺酸)。我们将研究最丰富的抗氧化防御物质谷胱甘肽(GSH)和调节氧化应激反应的转录因子Nrf2之间的关系。我们的具体目标是：1)阐明谷胱甘肽与胚胎发育过程中NRF2污染激活的关系，并创建胚胎氧化还原图谱；2)确定氧化剂暴露历史如何影响NRF2激活和毒物敏感性；3)确定氧化应激、谷胱甘肽和NRF2激活在胰腺β细胞异常发育中的作用，并确定胰腺器官发生的关键敏感窗口。这项研究将导致对早期生命中化学物质暴露和氧化应激如何损害发育中的胰腺并使人类容易患糖尿病和其他潜在疾病的机械性理解。这项工作还将阐明一个知之甚少但却至关重要的基本生物学过程--角色 研究胚胎发育中的氧化还原环境--并确定缓解和转化毒理学的具体目标。

 DESCRIPTION (provided by applicant): Early life stage exposures to environmental contaminants can result in aberrant pancreatic β-cell development, which may predispose an individual to diabetes. A common mode of toxicity shared by numerous, diverse environmental contaminants is the generation of reactive oxygen species (ROS) and oxidative stress. ROS and cellular redox potential play fundamental roles in normal embryonic development and cell signaling. Perturbation of these processes resulting from contaminant exposure can alter cell fate decisions, resulting in functional or structural alterations that only become apparent with subsequent stress or age. However, surprisingly little is known about how embryos respond to oxidative stress, or the impact of toxicant exposures on pancreas development. The long-term goal of this research is to understand how embryos respond to oxidative stress, and how toxicant exposures contribute to the developmental origins of diabetes. The zebrafish (Danio rerio) is a well-established, widely used, and powerful model organism for studying vertebrate embryonic development in vivo. To investigate how changes in the developmental redox microenvironment affect toxicant sensitivity and pancreatic β-cells at specific stages, we will us a fluorescent redox biosensor, redox imaging, and automated, time-lapse microscopy of transparent, transgenic zebrafish embryos exposed to environmental contaminants. This project will focus on environmentally relevant concentrations of persistent toxicants previously implicated in the etiology of diabetes (PCBs, phthalates, and the Teflon surfactant PFOS). We will examine the relationship between the most abundant antioxidant defense, glutathione (GSH), and the transcription factor Nrf2, that regulates the response to oxidative stress. Our specific aims are: 1) elucidate the relationship between GSH and contaminant activation of Nrf2 during embryonic development and create an embryo redox map; 2) determine how an oxidant exposure history affects Nrf2 activation and toxicant sensitivity, 3) ascertain the roles of oxidative stress, GSH, and Nrf2 activation in deviant pancreatic β-cell development, and identify critical sensitive windows of pancreas organogenesis. This research will lead to a mechanistic understanding of how early life chemical exposures and oxidative stress may damage the developing pancreas and predispose humans to diabetes and potentially other diseases. This work will also elucidate a poorly understood, but critical fundamental biological process- the role of the redox environment in embryonic development- and identify specific targets for mitigation and translational toxicology.