Gene Silencing Mechanisms in Drosophila

果蝇的基因沉默机制

• 批准号: 0211376
• 负责人: James Birchler
• 金额: $ 45万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0211376&HistoricalAwards=false
• 关键词: Gene; Silencing; Mechanisms; Drosophila

Genes transformed back into the organism of origin often cause silencing of dispersed homologous copies, including the endogenous gene. Two types of silencing occur. One is transcriptional and involves changes in chromatin structure as evidenced by the accumulation of Polycomb Group proteins on the silenced transgene insertion sites. The other involves post-transcriptional RNA turnover in a similar manner to RNA interference. Emerging evidence has indicated potential connections among RNA interference, post-transcriptional silencing and transcriptional transgene silencing. In this project, a genetic and molecular approach will be undertaken to determine any relationship among these types of silencing. Transgenes of the Alcohol dehydrogenase (Adh) and white (w) eye color genes in Drosophila will be used as a model system. First, a series of constructs will be transformed that do or do not exhibit gene expression to determine whether transcriptional silencing requires the expression of the silencing gene to occur. If silencing can only occur when the homologous sequences are expressed, an RNA mediated process would be implicated in causing the chromatin changes that are associated with the cases of transcriptional silencing. Secondly, the interrelationship between RNAi-like mechanisms and transcriptional silencing will be examined. A construct predicted to induce post-transcriptional silencing of Adh will be tested for its ability to produce either type of silencing. Next, mutations that block post-transcriptional silencing will be tested for their influence on pairing sensitive silencing. Further, a transgene predicted to generate double stranded RNA homologous to Adh promoter regions will be produced and tested for its ability to induce transcriptional silencing. Studies of gene silencing are likely to reveal new information about gene expression and nuclear dynamics in multicellular eukaryotes. One role of these silencing mechanisms is as a protection against viruses and transposons, although many of the genes that have been identified in the process are also known to affect developmental mechanisms. Understanding the basic processes of gene silencing has the potential to lead to virus protection and to have applications in gene therapy.

转化回原始生物体的基因通常会导致分散的同源拷贝沉默，包括内源基因。 有两种类型的沉默。 一个是转录的，涉及染色质结构的变化，如在沉默的转基因插入位点上Polycomb组蛋白的积累所证明的。 另一个涉及转录后RNA周转，其方式与RNA干扰相似。 新出现的证据表明，RNA干扰，转录后沉默和转录转基因沉默之间的潜在联系。 在这个项目中，将采取遗传和分子方法来确定这些类型的沉默之间的任何关系。 果蝇中的醇脱氢酶（Adh）和白色（w）眼睛颜色基因的转基因将被用作模型系统。 首先，转化一系列表现出或不表现出基因表达的构建体，以确定转录沉默是否需要沉默基因的表达发生。 如果沉默只能在同源序列表达时发生，则RNA介导的过程将涉及引起与转录沉默情况相关的染色质变化。 其次，将研究RNAi样机制和转录沉默之间的相互关系。 将测试预测诱导Adh转录后沉默的构建体产生任一类型沉默的能力。 接下来，将测试阻断转录后沉默的突变对配对敏感性沉默的影响。 此外，将产生预测产生与Adh启动子区同源的双链RNA的转基因，并测试其诱导转录沉默的能力。基因沉默的研究有可能揭示多细胞真核生物基因表达和核动力学的新信息。 这些沉默机制的一个作用是作为对病毒和转座子的保护，尽管在该过程中已经确定的许多基因也已知会影响发育机制。 了解基因沉默的基本过程有可能导致病毒保护和基因治疗的应用。