Imprinting defects leading to Angelman and Prader Willi syndromes

项目总结 这个应用程序试图理解Angelman和Prader-Willi背后的遗传印记机制 综合症，两种终生神经行为障碍。拟议的研究将通过以下方式确定这些机制 哪个基因位点被印记，测试与印记缺陷有关的DNA元件的分子作用，以及 建立AS印迹缺陷动物模型。 与其他印记基因簇类似，印记中心(IC)负责单等位基因 在PWS-AS基因座的表达。在PWS-AS位点上的IC是两部分的，由PWS-IC和 AS-IC。PWS-IC在体细胞中工作，激活父系等位基因的基因表达。AS-IC 在卵母细胞中起到表观失活PWS-IC的作用，从而沉默父系表达的基因 关于未来母亲的等位基因。因此，AS-IC在该区域启动印记。小鼠AS-IC已经躲避了 检测，排除对AS-IC功能的机械性调查。然而，我们最近证明了 卵母细胞中通过PWS-IC的转录是正确印记的必要条件和充分条件 从该基因座衍生出的转基因。我们还发现卵母细胞活性转录启动子是必要的。 观察忠实的转基因印记。综上所述，这些结果表明，转录过程中 PWS-IC包括AS-IC活性。在第一个特定目标中，我们将修改内源PWS-AS基因座以进行测试 假设整个内源PWS-AS基因座由类似的基于转录的机制印记。 目标2将确定印记形成的发育窗口。AIM 3将提供第一个 AS-IC在人类卵母细胞中的功能特征，即其在其中发挥作用的组织。 在这些研究的结论中，我们将对印记是如何在 PWS-AS基因座，并将表征印记的发育阶段和细胞类型 发生。我们还将了解在人类中是否存在类似的机制，以及 当缺失时会导致AS的DNA序列。这些结果将为未来对AS原因的研究提供信息 由于AS-IC的缺失或频率增加而自发产生的印记缺陷 采用辅助生殖技术。

PROJECT SUMMARY This application seeks to understand genetic imprinting mechanisms underlying Angelman and Prader-Willi syndromes, two lifelong neurobehavioral disorders. The proposed studies will determine the mechanisms by which the locus is imprinted, test the molecular role of a DNA element implicated in AS imprinting defects, and create an AS imprinting defect animal model. Similar to other imprinted gene clusters, an imprinting center (IC) is responsible for monoallelic gene expression at the PWS-AS locus. The IC at the PWS-AS locus is bipartite, consisting of the PWS-IC and the AS-IC. The PWS-IC works in somatic cells to activate gene expression from the paternal allele. The AS-IC functions in oocytes to epigenetically inactivate the PWS-IC, and thereby silence paternally-expressed genes on the future maternal allele. The AS-IC thus initiates imprinting in the region. The murine AS-IC has evaded detection, precluding mechanistic investigations into AS-IC function. However we recently demonstrated that transcription transiting through the PWS-IC in oocytes is necessary and sufficient to correctly imprint transgenes derived from the locus. We also found that oocyte-active transcriptional promoters were necessary to observe faithful transgene imprinting. Together, these results indicate that transcription transiting across the PWS-IC comprises AS-IC activity. In the first specific aim we will modify the endogenous PWS-AS locus to test the hypothesis the entire endogenous PWS-AS locus is imprinted by a similar transcription-based mechanism. Aim 2 will determine the developmental window in which imprints are established. Aim 3 will provide the first functional characterization of the AS-IC in human oocytes, the tissue in which it functions. At the conclusion of these studies, we will have a mechanistic understanding of how imprints are established at the PWS-AS locus and will have characterized the developmental stage and cell type in which imprinting occurs. We will also understand whether a similar mechanism operates in humans, and the molecular role of DNA sequences that when deleted result in AS. These results will inform future studies of the causes of AS imprinting defects that arise spontaneously, as a result of a deletion of the AS-IC, or at increased frequency following assisted reproductive technologies.