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.

转化回起源生物的基因通常会导致分散的同源副本的沉默，包括内源基因。 发生了两种沉默。 一个是转录的，涉及染色质结构的变化，这是由多肉体组蛋白在沉默的转基因插入位点上的积累所证明的。 另一个涉及以与RNA干扰相似的方式转录后RNA更新。 新兴证据表明，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，将采用遗传和分子方法来确定这些类型的沉默之间的任何关系。 果蝇中酒精脱氢酶（ADH）和白色（W）眼颜色基因的转基因将用作模型系统。 首先，将转换一系列的构建体，该构建体发生或未表现出基因表达，以确定转录沉默是否需要表达沉默基因的表达。 如果只有在表达同源序列时才能进行沉默，则RNA介导的过程与引起与转录沉默相关的染色质变化。 其次，将研究类似RNAi的机制与转录沉默之间的相互关系。 预计会诱导ADH转录后沉默的构造将因其产生任何一种沉默的能力而进行测试。 接下来，将测试阻止转录后沉默的突变，以实现其对配对敏感沉默的影响。 此外，将产生与ADH启动子区域同源的双链RNA的转基因，并以其诱导转录沉默的能力进行测试。基因沉默的研究可能会揭示有关多细胞真核生物中基因表达和核动力学的新信息。 这些沉默机制的作用之一是保护病毒和转座子，尽管已知在此过程中鉴定出的许多基因也会影响发育机制。 了解基因沉默的基本过程有可能导致病毒保护并在基因治疗中应用。