MECHANISM AND FUNCTION OF GENOMIC IMPRINTING

基因组印记的机制和功能

• 批准号: 6180564
• 负责人: SHIRLEY M. TILGHMAN
• 金额: $ 31.09万
• 依托单位: PRINCETON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 2002-07-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6180564
• 关键词: DNA methylation; Marsupialia; Peromyscus; Prader Willi syndrome; Wilms' tumor; alleles; artificial chromosomes; biochemical evolution; embryonic stem cell; fluorescent in situ hybridization; gene expression; gene mutation; genetic enhancer element; genetic promoter element; genetic regulatory element; genetic transcription; genomic imprinting; happy puppet syndrome; laboratory mouse; molecular cloning; protein structure function; single cell analysis; transfection

DESCRIPTION (Adapted from investigator's abstract): A small number of genes in the mammalian genome are regulated by a process called genomic imprinting, whereby the maternal and paternal alleles are differentially expressed. The process requires a gamete-specific mark, most likely DNA methylation of specific sequences in the vicinity of imprinted genes. The mark is inherited from parents, and maintained in their progeny throughout life. Based on mutations in both humans and mice in imprinted genes, it is likely that the process evolved in mammals to regulated prenatal and possibly early postnatal growth. In human disruptions in imprinting have been implicated in three genetic syndromes, Beckwith-Wiedemann, Prader Willi and Angelman syndromes. Furthermore, loss of imprinting of specific genes has been observed in a large number of human tumors. This application proposes experiments to understand the number of human tumors. This application proposes experiments to understand the mechanism of genomic imprinting, as well as the function and evolution of the process. The laboratory is studying a cluster of imprinted genes on the distal end of mouse Chromosome 7 that include four maternally expressed genes that encode the growth factors insulin and insulin-like growth factor II. A model was proposed to explain the reciprocal imprinting of H19 and Igf2 in which the promoters of the two genes, which lie 90 kb apart, compete for transcriptional enhancers. Although there is substantial evidence in support of this model, the basis for the competition on the maternal chromosome is not completely understood. The investigators propose to generate two conditional mutations of the H19 gene, one in the promoter and a second in the 5' flank, to assess the relative importance of transcription of H19 versus a requirement for lack of methylation of the gametic mark in its 5' flank, for the imprinted silencing of Igf2. The nature of the gametic mark, and its acquisition of stable DNA methylation will be explored using both transfections and transgenic mice experiments. The proteins that act to prevent its methylation in the female germline and in somatic cells will be identified and cloned. The generality of the competition model will be explored by studying the genes at the telomeric end of the cluster. Gametic imprints will be identified and tested by transgenesis. To explore the importance of linkage for the imprinting of the genes in the region, specific translocations will be engineered in mice to dissociate the linkage of the genes. Finally the evolution of imprinting will be studied in the marsupial, Monodelphis, and in two strains of the wild mouse Peromyscus, where dramatic perturbations in growth are observed in reciprocal F1 hybrids.

描述（改编自研究者摘要）：少数 哺乳动物基因组中的基因是由一个叫做基因组学的过程调控的。 印记，由此母亲和父亲的等位基因是不同的 表达。这个过程需要一个配子特异性的标记，很可能是DNA 印迹基因附近特定序列的甲基化。的 标记是从父母那里遗传来的，并在他们的后代中一直保持着。 生活基于人类和小鼠印记基因的突变， 这一过程很可能在哺乳动物中进化到产前调节， 可能是出生后早期的生长。在人类的印记中断， 与三种遗传综合征有关，贝克维-维德曼，普拉德 Willi和Angelman综合征。此外，特定的印记的丧失 在大量的人类肿瘤中观察到了这些基因。这 申请提出了实验来了解人类肿瘤的数量。 本申请提出了实验，以了解的机制， 基因组印记，以及该过程的功能和进化。 实验室正在研究远端的一组印记基因 小鼠7号染色体，包括四个母系表达的基因， 编码生长因子胰岛素和胰岛素样生长因子II。一 提出了一个模型来解释H19和Igf 2的相互印迹， 这两个基因的启动子相距90 kb， 转录增强子。虽然有大量证据表明， 这种模式的支持下，产妇的竞争基础上， 染色体还不完全清楚。研究人员建议 产生H19基因的两个条件突变，一个在启动子中， 第二个在5'侧翼，以评估 H19转录与缺乏甲基化的要求 其5'侧翼有配子标记，用于Igf 2的印记沉默。的 配子标记的性质及其稳定的DNA甲基化的获得 将使用转染和转基因小鼠实验来探索。 在雌性生殖细胞中阻止甲基化的蛋白质 和体细胞中的基因将被识别和克隆。的一般性的 竞争模型将通过研究端粒的基因来探索 集群的结束。配子印记将由以下人员识别和检测： 转基因探讨联系对印刻的重要性 在该地区的基因，特定的易位将被工程化， 小鼠来分离这些基因的连锁。最后， 印记将在有袋动物Monodelphis中进行研究， 野生小鼠Peromyscus的品系，其中戏剧性的扰动， 在正反交F1杂种中观察到生长。