Dissecting the Trigger of the Chromatin Modification Cycle

生活世界通过前馈和反馈循环运行，建立了自我永续的模式，可以在巨大的时间尺度上持续下去。一个仍未得到解答的主要问题是，自我延续的生物周期最初是如何启动的。这个项目的优点是能够重复地触发一个这样的周期，创造了一个难得的机会来了解生物周期最初是如何启动的。这个项目使用尖端技术来理解第一个触发因素的机制，该触发因素负责启动一个前馈循环，调节新引入植物细胞的DNA。通过将新的DNA植入细胞，该项目将在实验上剖析启动调控的最早阶段的机制。该项目的结果将使学术界和工业界了解如何改进工厂，同时避免引发不必要的监管的麻烦循环。该项目还将直接培训下一代科学家，为他们提供全面的指导，为他们在生物学、数据分析和技术领域的职业生涯做好准备。此外，该项目将在东圣路易斯的杰基·乔伊纳·科西中心向新观众进行推广。这项计划将惠及那些传统上认为自己没有资格从事科学事业的群体，因为在科学领域缺乏有代表性的模特，并且非常适合杰基·乔伊纳·科西中心举办的课外计划。染色质修饰的建立是导致转座元件和一些转基因长期可遗传的表观遗传沉默的关键的第一步。一旦启动，染色质修饰，如胞嘧啶DNA甲基化，就会被复制，在植物中，可以在特定的位置跨世代繁殖几个世纪。然而，决定DNA甲基化如何首先定位于某个基因座的机制还知之甚少。支持该项目的初步数据包括建立研究第一轮新的(从头)染色质修饰的工具，这些数据表明，在一个位点产生支架非编码RNA是从头DNA甲基化所需的关键的里程碑事件。由于特定的RNA聚合酶(POLV)的招募来产生这些支架RNA，这种事件可以在植物中得到最好的研究。该项目的首要目标是了解支架RNA靶区是如何选择的，以及在从头DNA甲基化过程中如何首先招募Pol V。这项工作利用尖端技术在分子水平上剖析了一种未知的机制，负责建立从头DNA甲基化，并触发可转座元件和转基因的可遗传、表观遗传沉默的长期生物周期。该项目由分子和细胞生物科学部门的遗传机制计划和综合组织系统部门的植物基因组研究计划共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The living world functions through feed-forward and feed-back cycles, establishing self-perpetuating patterns that can persist over vast timescales. A major question that remains unanswered is how self-perpetuating biological cycles are first initiated. This project has the advantage of being able to trigger one such cycle reproducibly, generating a rare opportunity to understand how a biological cycle is originally initiated. This project uses cutting-edge techniques to understand the mechanism of the first trigger responsible for initiating a feed-forward cycle that regulates DNA newly introduced into plant cells. By placing new DNA into cells, this project will experimentally dissect the mechanism of the earliest stages initiating regulation. The results of this project will inform academics and industry on how to improve plants while avoiding the initiation of troublesome cycles of unwanted regulation. This project will also directly train the next generation of scientists, providing them with thorough mentoring to prepare them for careers in biology, data analysis and technology. In addition, this project will perform outreach to a new audience at the Jackie Joyner Kersee Center in East St. Louis. This program will benefit groups that have traditionally not seen themselves as eligible for a career in science due to lack of representative models in science, and is perfectly suited for the after school programs run by the Jackie Joyner Kersee Center. The establishment of chromatin modifications is an essential first step that leads to the long-term heritable epigenetic silencing of transposable elements and some transgenes. Once initiated, chromatin modifications such as cytosine DNA methylation, are replicated and, in plants, can be propagated at specific loci across generations for centuries. However, the mechanisms dictating how DNA methylation is first targeted to a locus is poorly understood. The preliminary data in support of this project involved building the tools to study the first round of new (de novo) chromatin modification, and these data demonstrate that the production of scaffolding, non-coding RNAs at a locus is the key, milestone event required for de novo DNA methylation. This kind of event can be best studied in plants due to the recruitment of a specific RNA Polymerase (Pol V) to generate these scaffold RNAs. The overarching goals of this project are to understand how scaffold RNA target regions are selected and how Pol V is first recruited during de novo DNA methylation. This work utilizes cutting-edge techniques to dissect, at the molecular level, an unknown mechanism responsible for establishing de novo DNA methylation and triggering the long-term biological cycle of heritable, epigenetic silencing of transposable elements and transgenes.This project is co-funded by the Genetic Mechanisms Program in the Molecular and Cellular Biosciences Division and by the Plant Genome Research Program in the Integrative Organismal Systems Division.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.