Molecular biomarkers of exposure to an endocrine disrupting herbicide

描述(由申请人提供)：公众对内分泌干扰性化学品(EDCs)对人类健康的潜在影响的担忧，增加了评估接触这些化学品的机制影响的研究的必要性。在发育的关键时期接触EDC可导致组织分化的不可逆转变化，改变后代的性别和长期生殖潜力，支持这些较晚寿命影响的发育起源。在许多研究中，较晚的寿命影响归因于基因组的表观遗传变化。虽然一些研究集中在DNA甲基化作为毒性的表观遗传机制，但很少有研究调查microRNAs(MiRNAs)的作用。MiRNAs是调节基因和蛋白质表达的小RNA。在毒理学研究中，miRNAs在神经内分泌、生殖功能和疾病中发挥作用，并在化学暴露后发生改变，但尚未作为阿特拉津(ATR)毒性的表观遗传学机制进行研究。ATR是一种农业除草剂，据报道，它会污染美国各地的饮用水供应。ATR被认为是一种内分泌干扰物和潜在的致癌物。据报道，ATR作用于下丘脑-垂体-性腺轴，但ATR的内分泌干扰特性尚不完全清楚。在我们正在进行的研究中，在斑马鱼模型系统中，受精后1至72小时内发育的ATR暴露(HPF)后立即进行的转录分析支持HPG轴的变化和ATR内分泌干扰的神经内分泌控制变化。此外，成年斑马鱼在发育过程中暴露于ATR，并在正常实验室条件下成熟，显示出生活史特征和生殖功能的显著变化。我们的中心假设是，发育中ATR暴露引起的HPG轴的变化是由表观遗传机制驱动的。此外，我们假设ATR内分泌紊乱改变受神经内分泌控制。我们研究的长期目标是定义和联系控制ATR诱导的HPG轴改变的发育起源的遗传和表观遗传机制。在这项研究中，我们将首先确定发育ATR暴露后miRNA表达的变化，以确定ATR毒性的表观遗传靶点。在第二和第三个目标中，我们将对发育过程中暴露于ATR的成年雌性和雄性斑马鱼的脑/垂体和性腺组织进行比较转录分析。成年斑马鱼脑组织的初步转录数据进一步支持HPG信号的改变。还将进行大量的确证和靶向分析，以进一步研究ATR对HPG轴的毒性机制。在目标2和3中收集的数据将与目标1的数据相结合，以将ATR诱导的变化的发育起源的遗传和表观遗传机制与HPG轴联系起来。此外，在整个学习过程中，研究生和本科生将在进行科学研究的各个方面发挥积极作用并获得丰富的经验。

DESCRIPTION (provided by applicant): Public concern about the potential effects of endocrine disrupting chemicals (EDCs) on human health has heightened the need for research that assesses the mechanistic effects of exposure to these chemicals. EDC exposure during critical periods of development can result in irreversible changes in tissue differentiation alterig the sex and long-term reproductive potential of offspring supporting a developmental origin of these later lifespan impacts. The later lifespan impacts in many studies are attributed to epigenetic changes in the genome. While a number of studies have focused on DNA methylation as an epigenetic mechanism of toxicity, few studies have investigated the role of microRNAs (miRNAs). miRNAs are small RNAs that regulate expression of genes and proteins. miRNAs play a role in neuroendocrine and reproductive function and disease and are altered following chemical exposure in toxicology studies, but have yet to be investigated as an epigenetic mechanism of atrazine (ATR) toxicity. ATR is an agricultural herbicide commonly reported to contaminate drinking water supplies throughout the United States. ATR is implicated as an endocrine disruptor and a potential carcinogen. ATR is reported to act upon the hypothalamus-pituitary-gonadal (HPG) axis, but the endocrine disrupting properties of ATR are not completely understood. In our ongoing study, transcriptomic analysis immediately following a developmental ATR exposure from 1 to 72 hours post fertilization (hpf) in the zebrafish model system supports alterations in the HPG axis and neuroendocrine control of ATR endocrine disruption alterations. Furthermore, adult zebrafish developmentally exposed to ATR and allowed to mature under normal laboratory conditions exhibited significant alterations in life history traits and reproductive function. Our central hypothesis is that alterations in the HPG axi from a developmental ATR exposure are driven by epigenetic mechanisms. In addition, we hypothesize that ATR endocrine disruption alterations are under neuroendocrine control. The long term goal of our study is to define and link the genetic and epigenetic mechanisms governing the developmental origin of ATR-induced alterations on the HPG axis. In this study we will first identify miRNA expression alterations immediately following a developmental ATR exposure to define epigenetic targets of ATR toxicity. In the second and third aims, we will perform comparative transcriptomic analysis of brain/pituitary and gonadal tissue isolated from adult female and male zebrafish developmentally exposed to ATR. Preliminary transcriptomic data with adult zebrafish brain tissue further supports alterations in HPG signaling. A multitude of confirmation and targeted assays will also be performed to further investigate mechanisms of ATR toxicity on the HPG axis. The data collected in aims 2 and 3 will be coupled to that of aim 1 to link genetic and epigenetic mechanisms of the developmental origin of ATR-induced alterations to the HPG axis. Moreover, throughout this study graduate and undergraduate students will play an active role and gain extensive experience in all aspects of conducting a scientific research study.