ENVIRONMENTAL IMPACT ON THE EMBRYONIC MTDNA GENOME

描述：(改编自《调查者摘要》)长期 这项研究的目的是阐明线粒体DNA的作用 (MtDNA)在环境致畸机制中的作用。 本文提出的研究是针对胚胎线粒体DNA的表达。 汞致小鼠神经管畸形的机制。小白鼠 胚胎在从厌氧代谢到有氧代谢的过程中起着至关重要的作用 在8体节和28体节的发育阶段之间。氧化的 转换可以通过16S核糖体RNA(16S RRNA)来模拟。已编码 在mtdna基因组中，16srrna转录本是一种重要的结构。 线粒体核糖体的组成部分。它被上调为 黄瓜8-体节和28-体节之间的氧化转变研究进展 缺乏P53肿瘤抑制基因的胚胎的发育和去调控 基因和暴露在低水平汞的胚胎中。这些观察结果 为P53在对照中的亚凋亡性功能奠定基础 胚胎新陈代谢。假设一是发育变化 在16S rRNA中，P53非依赖和P53依赖的表达分区 控件，并且这些控件在开发过程中以不同的方式访问 氧化过渡期的前脑和心脏。假设二是 汞干扰P53依赖的16S RNA生物发生控制 在诱导前脑畸形的过程中，阻断直接 P53在线粒体DNA基因组中的信号转导作用。具体目标1将衡量 前脑和前脑中P53敏感和不敏感的16S RNA池 心脏在8体节和28体节发育阶段之间，以及在 低浓度汞致畸形的发病机制。 特异性目标2将关联P53敏感的16S RNA池的变化 临界暴露过程中线粒体P53蛋白和线粒体DNA结合 汞致畸形期。具体目标3将决定 16S RNA池和mtDNA基因组稳定性的慢性变化程度 稳定地使用胚胎细胞在功能上依赖于线粒体P53 线粒体靶向跨显性阴性P53基因的转染 小蛋白。这些实验将为未来的研究奠定基础 利用线粒体靶向的P53探索体内功能关系 转基因小鼠，以及对一种新的 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.