Developmental Functions of SNR1 and the BRM Chromatin Remodeling Complex in Drosophila

果蝇中 SNR1 和 BRM 染色质重塑复合体的发育功能

• 批准号: 0818620
• 负责人: Andrew Dingwall
• 金额: $ 56.51万
• 依托单位: Loyola University Stritch School of Medicine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0818620&HistoricalAwards=false
• 关键词: Developmental; Functions; SNR1; BRM; Chromatin

Intellectual merit of the project: Access to genetic information embedded within the genome is essential for the proper development of all eukaryotic organisms from simple yeast to vertebrate animals; thus, it is of great importance to understand the cellular processes that guide proper gene regulation in vivo. Several key steps involved in gene regulation require chromatin remodeling, defined as the alteration of DNA-Histone contacts that comprise the basic building blocks of the genome. Recent advances have revealed that chromatin remodeling "complexes" that include multiple proteins are essential cofactors in initiating transcription on chromosomal templates during development, as well as the regulation of alternative splicing and epigenetic control of gene expression. Although considerable progress has been made in recent years in our understanding of the biochemical mechanism of chromatin remodeling, fundamental questions remain as to how chromatin remodeling complexes are targeted to certain genes in vivo and how they contribute mechanistically to both transcription activation and repression. This project explores the role of the Drosophila Brahma (SWI/SNF) chromatin remodeling complex in coordinating hormone signaling with gene regulation at developmentally appropriate time points through effects on transcript elongation by RNA Polymerase II--an exciting and unexpected role only recently discovered. The Drosophila SNR1 and BRM proteins are core components of the Brahma complex, which is highly conserved among all eukaryotes. This project uses unique genetic and biochemical tools in both fruitflies and cultured cell systems to unravel the functional relationships among complex components, including the ATPase subunit BRM and the critical regulatory subunit, SNR1. These analyses will help to define the mechanisms of in vivo target gene selection and regulation by chromatin remodeling complexes. The relationships between the Brahma complex and nuclear receptor coactivators that direct the hormone response pathway are also the focus of this investigation. While coactivator complexes have been identified in both insects and vertebrates and there are strong links between chromatin remodeling and coactivator function, the biological roles of individual components are poorly understood. This project focuses on a biological analysis of the cmi gene, encoding a conserved homolog of the N-terminal portion of the mammalian ALR1/MLL2 protein found as a component of several nuclear receptor coactivator complexes. Through the deployment of recently generated genetic tools this project will enable an unprecedented dissection of the normal functions of cmi. These analyses will provide an important model system to help understand coactivator functions in metazoan development and the relationship with chromatin remodeling. These studies using Drosophila as a genetic model system will provide greater understanding of the basic mechanisms by which chromatin remodeling complexes participate in programming gene expression during development, as the regulatory systems in flies and vertebrates are remarkably similar, including transcription control and nuclear receptor function. Thus, the results of this project should provide important insights to help biologists better understand chromatin remodeling functions as well as the regulation of RNA polymerase elongation in diverse systems.Broader impact of the project. Graduate (both MS and PhD), undergraduate and several high school students directly participate in the research projects and are trained by the PI and senior personnel. Women and minorities are highly represented. Multidisciplinary training is a vital aspect of education to prepare students for diverse science careers and this project takes full advantage of the unique tools currently available for Drosophila research. Students are trained in molecular and developmental genetics, biochemistry, molecular biology and bioinformatics/structural biology. Student research (both graduate and undergraduate) is frequently included in publications. Students are encouraged to present their work at local, regional and national meetings and to collaborate with expert investigators outside the institution to enhance their training experience.

该项目的智力价值：获取嵌入基因组中的遗传信息对于从简单酵母到脊椎动物的所有真核生物的正常发育至关重要；因此，了解指导体内正确基因调控的细胞过程非常重要。基因调控涉及的几个关键步骤需要染色质重塑，染色质重塑定义为构成基因组基本构建模块的 DNA-组蛋白接触的改变。最近的进展表明，包含多种蛋白质的染色质重塑“复合物”是发育过程中在染色体模板上启动转录以及可变剪接和基因表达的表观遗传控制的调节的重要辅助因子。尽管近年来我们对染色质重塑的生化机制的理解取得了相当大的进展，但关于染色质重塑复合物如何靶向体内某些基因以及它们如何在机制上促进转录激活和抑制，仍然存在基本问题。该项目探讨了果蝇 Brahma (SWI/SNF) 染色质重塑复合物在发育适当时间点通过 RNA 聚合酶 II 对转录物延伸的影响来协调激素信号传导与基因调控的作用，这是最近才发现的令人兴奋且意想不到的作用。果蝇SNR1和BRM蛋白是Brahma复合体的核心成分，在所有真核生物中高度保守。该项目在果蝇和培养细胞系统中使用独特的遗传和生化工具来揭示复杂成分之间的功能关系，包括 ATP 酶亚基 BRM 和关键的调节亚基 SNR1。这些分析将有助于定义体内靶基因选择和染色质重塑复合物调节的机制。梵天复合体和指导激素反应途径的核受体共激活剂之间的关系也是本次研究的重点。虽然在昆虫和脊椎动物中都发现了共激活因子复合物，并且染色质重塑和共激活因子功能之间存在密切联系，但对各个成分的生物学作用知之甚少。该项目重点对 cmi 基因进行生物学分析，该基因编码哺乳动物 ALR1/MLL2 蛋白 N 端部分的保守同源物，该蛋白是多种核受体共激活复合物的组成部分。通过部署最近生成的遗传工具，该项目将对 cmi 的正常功能进行前所未有的剖析。这些分析将提供一个重要的模型系统，以帮助了解后生动物发育中的共激活子功能以及与染色质重塑的关系。这些使用果蝇作为遗传模型系统的研究将有助于更好地了解染色质重塑复合物参与发育过程中基因表达编程的基本机制，因为果蝇和脊椎动物的调节系统非常相似，包括转录控制和核受体功能。因此，该项目的结果应该提供重要的见解，帮助生物学家更好地了解染色质重塑功能以及不同系统中RNA聚合酶延伸的调节。该项目的影响更广泛。 研究生（硕士和博士）、本科生和多名高中生直接参与研究项目并接受PI和高级人员的培训。妇女和少数族裔的比例很高。多学科培训是教育的一个重要方面，可以帮助学生为不同的科学职业做好准备，该项目充分利用了目前可用于果蝇研究的独特工具。学生接受分子和发育遗传学、生物化学、分子生物学和生物信息学/结构生物学方面的培训。学生研究（研究生和本科生）经常包含在出版物中。鼓励学生在地方、区域和国家会议上展示他们的工作，并与机构外的专家研究人员合作，以增强他们的培训经验。