Writing and Interpreting the Chromatin Enhancer Code in Myeloid Cells

写入和解释骨髓细胞中的染色质增强子代码

• 批准号: 8256242
• 负责人: Steven Zvi Josefowicz
• 金额: $ 4.92万
• 依托单位: ROCKEFELLER UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8256242
• 关键词: Address; Affect; Binding; Biochemical; Biological Models; Biology; Cell Differentiation process; Cell Lineage; Cells; Characteristics; Chromatin; Code; Coenzymes; Complex; Defect; Dependency; Development; Enhancers; Epigenetic Process; Gene Expression; Genetic Transcription; Genome; Genomics; Health; Hematopoietic; Heritability; Heterogeneity; Histone Code; Histones; Human; Knowledge; Life; Link; Location; Maintenance; Mammalian Cell; Modeling; Modification; Molecular; Myelogenous; Myeloid Cells; Organism; Pathway interactions; Post-Translational Protein Processing; Recruitment Activity; Regulation; Relative (related person); Role; Secondary to; Specific qualifier value; Specificity; Techniques; Testing; Transcription Factor AP-1; Variant; Writing; cell type; enzyme activity; improved; in vivo; loss of function; mouse model; novel; programs; proto-oncogene protein Spi-1; transcription factor; tumorigenesis

DESCRIPTION (provided by applicant): Temporal and spatial control of gene expression in metazoan organisms defines cellular heterogeneity, cell type-specific phenotypic specialization, and cell lineage stability. This proposal pursues the description of mechanisms for the establishment of selective and heritable regulatory chromatin landscapes and gene expression programs in distinct mammalian cell lineages. Specifically, utilizing a combination of novel mammalian model systems and established models and techniques I aim to determine how cell lineage specifying transcription factors affect and collaborate with characteristic lineage specifi regulatory chromatin features, such as incorporation of the histone variant H3.3 and monomethylation of H3K4 (H3K4me1), in directing cellular differentiation. The transcription factor PU.1 directs myeloid cell differentiation together with C/EBP1 and AP1, and is clearly linked, spatiotemporally, to lineage specific enhancers decorated with H3K4me1 and other characteristic "enhancer histone code" modifications. Using biochemical approaches, I propose to investigate the histone modifying enzyme activity and cofactor identity contained within myeloid lineage specifying transcription factor complexes. Transcription factors may directly recruit chromatin machinery to lineage specific enhancers, or alternatively, these factors may be sequentially recruited in a chromatin template dependent manner and the relative contributions of these possible mechanisms for establishing and propagating lineage specific chromatin landscapes will be assessed. Additionally, using well- established models of hematopoietic cell differentiation and phenotypic analysis combined with novel mouse models, the functional requirements for H3.3 in cellular differentiation and lineage maintenance will be assessed in vivo. Additionally, I will employ genomic analytical techniques for characterization of discrete functional effects of H3.3 on associated chromatin characteristics such as accessibility, enhancer transcription, and post-translational modification of histones. These studies will address an outstanding question in the field of chromatin biology and epigenetics, namely, how lineage specifying transcription factors template lineage specific chromatin landscapes defining developmental potential, responsiveness to secondary factors, and heritable transcription programs. Increased knowledge of mechanisms of cell fate determination will enhance our understanding of how these epigenetic mechanisms impact human health, during development and in tumorogenesis. PUBLIC HEALTH RELEVANCE: Eukaryotic life is characterized by thousands of differentiated cell types which all derive their "programming" from a single genome. These studies aim to reveal mechanisms for regulation of chromatin characteristics that control the establishment and heritable maintenance of cell type-specific gene expression programs. Alterations in these pathways can result in developmental defects and tumorigenesis, and therefore, an improved understanding of how transcription factors and chromatin features together control cellular differentiation and identity will have an important impact on human health.

描述（由申请人提供）：后生动物生物中基因表达的时空控制定义了细胞异质性、细胞类型特异性表型特化和细胞谱系稳定性。本提案旨在描述在不同的哺乳动物细胞系中选择性和可遗传的染色质调控景观和基因表达程序的建立机制。具体来说，利用新型哺乳动物模型系统和已建立的模型和技术的结合，我的目标是确定指定转录因子的细胞谱系如何影响和协同特征谱系特定的调节染色质特征，如组蛋白变体H3.3的结合和H3K4的单甲基化（H3K4me1），以指导细胞分化。转录因子PU.1与C/EBP1和AP1一起指导髓细胞分化，并且在时空上与带有H3K4me1修饰和其他特征性“增强子组蛋白编码”修饰的谱系特异性增强子明显相关。使用生化方法，我建议研究组蛋白修饰酶活性和辅助因子的身份包含在髓系谱系指定转录因子复合物。转录因子可能直接将染色质机制招募到谱系特异性增强子，或者，这些因子可能以依赖染色质模板的方式依次招募，这些可能的机制在建立和繁殖谱系特异性染色质景观方面的相对贡献将被评估。此外，利用成熟的造血细胞分化模型和表型分析结合新型小鼠模型，将在体内评估H3.3在细胞分化和谱系维持中的功能需求。此外，我将采用基因组分析技术来表征H3.3对相关染色质特征的离散功能影响，如可及性、增强子转录和组蛋白的翻译后修饰。这些研究将解决染色质生物学和表观遗传学领域的一个突出问题，即谱系如何指定转录因子模板谱系特定染色质景观定义发育潜力，对次要因素的反应性和可遗传的转录程序。增加对细胞命运决定机制的了解将增强我们对这些表观遗传机制在发育和肿瘤发生过程中如何影响人类健康的理解。