Epigenetic Regulation of the Mutator System of Transposons

转座子突变系统的表观遗传调控

• 批准号: 0321726
• 负责人: Michael Freeling
• 金额: $ 98.68万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0321726&HistoricalAwards=false
• 关键词: Epigenetic; Regulation; Mutator; System; Transposons

Transposable elements, or transposons, are short stretches of DNA that can move from place to place within genomes. Often they move into, and thus mutagenize, other genes. Because of this propensity, transposons have become remarkably useful mutagens, as they both mutate and "tag" genes, allowing for their rapid recovery, particularly in large, unsequenced genomes such as maize. In maize, the Mutator transposon system has become the primary means by which genes are mutagenized and cloned. The system is composed of a number of different classes of elements, all of which are regulated by the MuDR class. Mutator (Mu) is remarkably active; elements can duplicate themselves at frequencies exceeding one new insertion per element per generation, resulting in massive increases in mutation frequencies. In order to exploit the systems utility, it is necessary to understand its regulation. The aspect of Mu regulation that is least understood involves epigenetic modification of otherwise active MuDR elements. Epigenetic modification involves changes in gene activity without changes in DNA sequence. In the case of Mutator these changes can result in a heritable loss of activity. This project seeks to understand the nature of epigenetic shifts in Mutator system. The project will exploit the availability of a minimal Mutator line, which, unlike those lines used for mutagenesis, carries a single MuDR element at a known chromosomal position. Mutations and chemical agents that either silence or reactivate this single MuDR element will be used to dissect the molecular events that correspond to these changes in Mutator activity. Using the minimal Mutator system it will also be possible to separate the processes involved in the initiation of silencing from those involved in its maintenance, an open question for a variety of epigenetically regulated phenomena. In addition, the system will be used to examine the effects of a large number of mutations in chromatin remodeling genes in maize that are being developed at the University of Arizona as part of a previously funded project. It is expected that this research will make the Mutator system significantly more useful to the maize community, and that it will illuminate a variety of questions concerning epigenetic silencing, both in maize and in other organisms. Of particular and immediate use to the maize community will be a locus we have identified designated Mu killer (Muk), which can silence otherwise highly active and mutagenic maize Mu lines. Lines carrying the Muk locus will be made available, along with instructions as to their use. In addition, initial results of interactions between mutations affecting chromatin structure and silenced MuDR elements will be made public on the University of Arizona chromatin database(ChromDB: http://www.chromdb.org/) as they become available.

转座因子或转座子是一小段DNA，可以在基因组内从一个地方移动到另一个地方。 它们经常进入其他基因，从而引起突变。 由于这种倾向，转座子已经成为非常有用的诱变剂，因为它们既突变又“标记”基因，允许它们快速恢复，特别是在大的、未测序的基因组中，如玉米。 在玉米中，Mutator转座子系统已成为诱变和克隆基因的主要手段。 该系统由许多不同类别的元素组成，所有这些元素都由MuDR类别进行调节。 突变子（Mutator，Mu）非常活跃;每一代每个元素可以以超过一个新插入的频率复制自己，导致突变频率的大幅增加。 为了利用系统效用，有必要了解其监管。 Mu调控的方面是最不了解的，涉及表观遗传修饰，否则活跃的MuDR元件。 表观遗传修饰涉及基因活性的改变而不改变DNA序列。 在Mutator的情况下，这些变化可能导致可遗传的活性丧失。 该项目旨在了解Mutator系统中表观遗传变化的性质。 该项目将利用最小突变株系的可用性，与用于诱变的那些株系不同，该株系在已知的染色体位置携带单个MuDR元件。将使用沉默或重新激活该单个MuDR元件的突变和化学试剂来剖析对应于这些Mutator活性变化的分子事件。 使用最小突变子系统，也将有可能将参与沉默起始的过程与参与其维持的过程分开，这是各种表观遗传调节现象的一个开放问题。 此外，该系统还将用于研究玉米染色质重塑基因中大量突变的影响，这些基因正在亚利桑那大学开发，作为先前资助项目的一部分。 预计这项研究将使Mutator系统对玉米社区更加有用，并且它将阐明玉米和其他生物中有关表观遗传沉默的各种问题。 对玉米群体特别和直接的用途将是我们已经鉴定的指定Mu杀手（Muk）的基因座，其可以沉默否则高度活性和诱变的玉米Mu系。 将提供携带Muk轨迹的线路，沿着使用说明。此外，影响染色质结构的突变和沉默的MuDR元件之间相互作用的初步结果将在亚利桑那大学染色质数据库（ChromDB：http：//www.chromdb.org/）上公开。