Histone H3 Phosphorylation and Gene Silencing in Chlamydomonas and Arabidopsis

衣藻和拟南芥中的组蛋白 H3 磷酸化和基因沉默

• 批准号: 1052281
• 负责人: Heriberto Cerutti
• 金额: $ 59.17万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1052281&HistoricalAwards=false
• 关键词: Histone; H3; Phosphorylation; Gene; Silencing

Intellectual Merit. The growth and development of multicellular organisms is determined by complex interactions between their genetic make-up and the environment. The different types of cells, tissues, and organs are ultimately defined by differential gene expression. Each particular cell type only expresses a unique fraction of the information contained in its genetic material, whereas the rest remains silenced. In some cases, this gene silencing involves heritable (but reversible) mechanisms, termed epigenetic. Epigenetic silencing can occur by covalent chemical modification of chromatin, the complex structure consisting of DNA wrapped around an octamer of proteins, known as histones. One significant challenge in the chromatin field is to define the molecular events that link histone modifications with specific biological outcomes, such as transcriptional activation or silencing. An added level of complexity is that the language of covalent histone modifications may not be universal across evolutionarily diverse organisms. This project will focus on two types of modification that occur on adjacent amino acids in the histone H3 molecule--phosphorylation of threonine 3 (H3T3p) and methylation of lysine 4 (H3K4me). The goals are to understand how these modifications control gene expression in two diverse evolutionary lineages, the green alga Chlamydomonas reinhardtii and the model plant Arabidopsis thaliana under normal growth conditions and in response to environmental change. Research will focus on studying the enzymes responsible for phosphorylating H3T3 and demethylating H3K4, searching for proteins that interact with these modified amino acids, and exploring the role of these modifications in response of Arabidopsis to osmotic stress. Results will contribute to the understanding of the molecular mechanisms involved in determining chromatin silencing states, their differences and/or similarities in evolutionarily divergent lineages, and their role in effecting changes in gene expression under environmental stresses.Broader Impacts. The project will have an impact on human resource development through the direct training of undergraduate and graduate students and one postdoctoral fellow. Students will learn research methodology via hands on experience, with the goal of fostering their interest in scientific discovery. The laboratory findings will be used to stimulate the learning process and to promote discussions on the benefits of plant science research in two plant biology courses. The training of a postdoctoral fellow for a career which combines research and education is also a central component of the project. Additionally, students will participate in a number of programs devoted to the training of minority individuals and in outreach activities with a non-profit organization working to educate the public on the nature and importance of science. Besides advancing our knowledge in chromatin biology and the evolution of histone modifying mechanisms, the results from this project may have practical implications for agriculture. A better understanding of epigenetic gene silencing mechanisms may lead to improvements in transgenic technology. In addition, microalgae are emerging as a suitable resource for the production of renewable carbon-neutral biofuels and a greater knowledge of the regulatory mechanisms that control gene expression and metabolism may become crucial for their commercial development.

智力优点。 多细胞生物的生长和发育是由其遗传组成与环境之间复杂的相互作用决定的。不同类型的细胞、组织和器官最终由差异基因表达来定义。每种特定的细胞类型仅表达其遗传物质中所含信息的独特部分，而其余部分则保持沉默。在某些情况下，这种基因沉默涉及可遗传（但可逆）的机制，称为表观遗传。表观遗传沉默可以通过染色质的共价化学修饰来实现，染色质是由包裹在八聚体蛋白质（称为组蛋白）周围的 DNA 组成的复杂结构。染色质领域的一项重大挑战是定义将组蛋白修饰与特定生物学结果（例如转录激活或沉默）联系起来的分子事件。更复杂的是，共价组蛋白修饰的语言可能在进化多样化的生物体中并不通用。该项目将重点关注组蛋白 H3 分子中相邻氨基酸上发生的两种类型的修饰——苏氨酸 3 (H3T3p) 的磷酸化和赖氨酸 4 (H3K4me) 的甲基化。 目标是了解这些修饰如何控制两个不同进化谱系（绿藻莱茵衣藻和模式植物拟南芥）在正常生长条件下和响应环境变化时的基因表达。 研究重点是研究负责磷酸化 H3T3 和去甲基化 H3K4 的酶，寻找与这些修饰的氨基酸相互作用的蛋白质，并探索这些修饰在拟南芥响应渗透胁迫中的作用。 结果将有助于理解决定染色质沉默状态的分子机制、它们在进化上不同谱系中的差异和/或相似性，以及它们在环境压力下影响基因表达变化中的作用。更广泛的影响。 该项目将通过直接培训本科生和研究生以及一名博士后对人力资源开发产生影响。学生将通过实践经验学习研究方法，目的是培养他们对科学发现的兴趣。实验室研究结果将用于刺激学习过程并促进两门植物生物学课程中关于植物科学研究益处的讨论。对博士后研究员进行研究和教育相结合的职业培训也是该项目的核心组成部分。此外，学生还将参加一些致力于少数族裔个人培训的项目，以及与非营利组织一起开展的外展活动，该组织致力于教育公众科学的本质和重要性。除了提高我们在染色质生物学和组蛋白修饰机制进化方面的知识之外，该项目的结果可能对农业具有实际意义。更好地了解表观遗传基因沉默机制可能会导致转基因技术的改进。此外，微藻正在成为生产可再生碳中性生物燃料的合适资源，对控制基因表达和代谢的调控机制的更多了解可能对其商业发展至关重要。