ENVIRONMENTAL IMPACT ON THE EMBRYONIC MTDNA GENOME

描述：（改编自研究者摘要）长期 本研究的目的是阐明线粒体DNA的作用 线粒体DNA（mtDNA）在环境因素诱导的畸形发病机制中的作用。 本文提出的研究是针对胚胎线粒体DNA表达的， 汞诱导的小鼠神经管缺陷（NTDs）的机制。 鼠标 胚胎从无氧代谢向有氧代谢进行了必要的转变 在8体节和28体节发育阶段之间。 氧化 转换可以通过16S核糖体RNA（16S rRNA）建模。 编码 在mtDNA基因组中，16S rRNA转录本是一种重要的结构蛋白， 线粒体核糖体的组成部分。 它被上调，因为 氧化转换的进展之间的8体节和28体节阶段的 在缺乏p53肿瘤抑制因子的胚胎中， 基因和胚胎暴露于低水平的汞。 这些观察结果 形成对照中p53的假定亚凋亡功能的基础 胚胎新陈代谢的过程。 假设一是， 在16SrRNA表达在p53非依赖性和p53依赖性之间分配中 控件，并且这些控件在开发中以不同方式访问。 前脑和心脏在氧化转换。 假设二是 汞干扰了16S RNA生物合成的p53依赖性控制， 在前脑畸形的诱导过程中， p53对mtDNA基因组的信号作用。 具体目标1将衡量 前脑中p53敏感和不敏感的16S RNA池， 心脏之间的8体节和28体节的发展阶段，并在 低浓度汞诱发畸形的发病机制。 特异性目的2将与p53敏感性16S RNA库的变化相关， 临界暴露过程中线粒体p53蛋白和mtDNA的结合 汞致畸形期。 具体目标3将决定 16S RNA库和mtDNA基因组稳定性的慢性变化程度 在功能上依赖于线粒体p53， 用经尿道靶向的反式显性阴性p53转染 迷你蛋白 这些实验将为未来的研究奠定基础， 使用经皮靶向p53探索体内功能关系 转基因小鼠，以及提供一个新的机制的见解， 汞引起的出生缺陷，也可能适用于其他 导致神经管缺陷的环境因素。

DESCRIPTION: (Adapted from the Investigator's Abstract) The long term objective of this research is to clarify the role of mitochondrial DNA (mtDNA) in pathogenesis of malformations induced by environmental agents. The research proposed here is directed at embryonic mtDNA expression in the mechanism of mercury-induced neural tube defects (NTDs) in mice. Mouse embryos make an essential switch from anaerobic to aerobic metabolism between the 8-somite and 28-somite stages of development. The oxidative transition can be modeled through the 16S ribosomal RNA (16S rRNA). Encoded in the mtDNA genome, the 16S rRNA transcript is an essential structural component of the mitochondrial ribosome. It is up regulated as the oxidative transition advances between the 8-somite and 28-somite stages of development, and de-regulated in embryos lacking the p53 tumor suppressor gene and in embryos exposed to low levels of mercury. These observations form the basis for a postulated sub-apoptotic function of p53 in the control of embryonic metabolism. Hypothesis one is that the developmental changes in 16S rRNA expression partition between p53-independent and p53-dependent controls, and these controls are differentially accessed in the developing prosencephalon and heart during oxidative transition. Hypothesis two is that mercury interferes with the p53-dependent control of 16S RNA biogenesis during induction of prosencephalic malformations, blocking a direct signaling effect of p53 on the mtDNA genome. Specific aim 1 will measure the p53-sensitive and insensitive 16S RNA pools in the prosencephalon and heart between the 8-somite and 28-somite stages of development, and during pathogenesis of malformations induced by low concentrations of mercury. Specific aim 2 will correlate changes in p53 sensitive 16S RNA pools of mitochondrial p53 protein and mtDNA-binding during the critical exposure period in mercury-induced malformation. Specific aim 3 will determine the extent to which chronic changes in 16S RNA pools and mtDNA genomic stability are functionally dependent on mitochondrial p53 using embryonic cells stably transfected with mitochondrially targeted transdominant-negative p53 miniprotein. These experiments will set the stage for future studies to explore functional relationships in vivo using mitochondrially-targeted p53 transgenic mice, as well as provide insights on a novel mechanism of mercury-induced birth defects that may also be applicable to other environmental agents that cause neural tube defects.