Molecular mechanisms of heterochromatin spreading at the leading edge

异染色质前沿扩散的分子机制

• 批准号: 2002231
• 负责人: Aaron Johnson
• 金额: $ 82.66万
• 依托单位: University of Colorado at Denver-Downtown Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-01 至 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2002231&HistoricalAwards=false
• 关键词: Molecular; mechanisms; heterochromatin; spreading; leading

Molecular mechanisms of heterochromatin spreading at the leading edgeThis project will uncover molecular details of how genes are stably turned off to produce different types of cells. Stable gene silencing can distinguish single-celled organisms and it also helps the human body use the same genome to create very different cell types that form organs. One major determinant of stable gene silencing is how far along a chromosome the wave of silencing spreads. Understanding how spreading occurs and how it is stopped are the primary focuses of this project. Achieving the goals of this project will help us understand variation across genetically identical cells that underlies development and environmental effects on gene regulation. The project will be undertaken by a team of scientists lead by the PI and including postdoctoral fellows, graduate students, and undergraduates. Summer research experiences for high school students and their teachers from a local school with a high minority population will enhance the training impact of the project. Together, the team will contribute to the research, combining their resources and skill sets while mentoring each other across levels. The results from this project will be broadly shared with the research community and the public and the resources generated will be made available to the scientific field.Heterochromatin is a genomic structure that represses transcription in a manner that is epigenetically maintained through cell division, contributing to stable cell differentiation in all eukaryotes. Establishment of a heterochromatin domain involves site-specific initiation and subsequent spreading across large regions of the genome, incorporating repressor proteins that stably associate with chromatin. Spreading is coupled to the conversion of histone modifications at the “leading edge” and eventual transition to the stable heterochromatin state. This mechanism requires two main modes of action for the heterochromatin machinery: dynamic spreading and stable repressive association with chromatin. While much is known of the components of heterochromatin in multiple systems, we do not understand at molecular resolution how the machinery coordinates the transitions through the steps of the mechanism. This project harnesses a purified budding yeast heterochromatin system that fully recapitulates the dynamic conversion of histone modifications and the formation of a stable repressive heterochromatin state. Previous work from the research group using this system has generated models for many steps in the mechanism that will now be tested at a new level of molecular resolution. Advanced cross-linking mass spectrometry will be used, combined with “designer” chromatin to capture the heterochromatin machinery in the multiple modes of action that drive formation of an epigenetic repressive genomic structure. The wealth of genetic and biochemical tools available will allow for identification of the most important molecular interactions for heterochromatin assembly, generating a new level of mechanistic understanding of this fundamental genomic regulatory system.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.

异染色质在前沿扩散的分子机制这个项目将揭示基因如何稳定关闭以产生不同类型细胞的分子细节。 稳定的基因沉默可以区分单细胞生物体，它也有助于人体使用相同的基因组来创造形成器官的非常不同的细胞类型。 稳定基因沉默的一个主要决定因素是沉默波沿着染色体沿着传播的距离。 了解传播如何发生以及如何停止是这个项目的主要重点。 实现该项目的目标将有助于我们了解遗传相同细胞之间的变异，这些变异是发育和环境对基因调控的影响的基础。 该项目将由PI领导的科学家团队进行，包括博士后研究员，研究生和本科生。 来自少数民族人口较多的当地学校的高中生及其教师的暑期研究经验将加强该项目的培训影响。 团队将共同为研究做出贡献，结合他们的资源和技能，同时在各个层面相互指导。 该项目的成果将广泛地与研究界和公众分享，所产生的资源将提供给科学领域。异染色质是一种基因组结构，它以一种通过细胞分裂表观遗传维持的方式抑制转录，有助于所有真核生物稳定的细胞分化。 异染色质结构域的建立涉及位点特异性起始和随后在基因组的大区域中扩散，掺入与染色质稳定缔合的阻遏蛋白。 扩散与组蛋白修饰在“前沿”的转化和最终向稳定的异染色质状态的转变相关联。 这种机制需要异染色质机制的两种主要作用模式：动态扩散和与染色质的稳定抑制缔合。 虽然在多个系统中异染色质的成分是已知的，但我们不了解在分子分辨率下，机器如何通过机制的步骤协调转换。 这个项目利用一个纯化的芽殖酵母异染色质系统，完全重现了组蛋白修饰的动态转换和稳定的抑制性异染色质状态的形成。 研究小组使用该系统的先前工作已经为该机制的许多步骤生成了模型，现在将在分子分辨率的新水平上进行测试。 将使用先进的交联质谱法，结合“设计者”染色质，以捕获异染色质机制的多种作用模式，驱动表观遗传抑制基因组结构的形成。 丰富的遗传和生物化学工具将允许识别最重要的分子相互作用的异染色质组装，产生一个新的水平的机械理解这一基本的基因组调控system.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。