Function of active chromatin domains in erythropoiesis

活性染色质结构域在红细胞生成中的功能

• 批准号: 7196385
• 负责人: MICHAEL D BULGER
• 金额: $ 31.39万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-15 至 2011-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7196385
• 关键词: Function; active; chromatin; domains; erythropoiesis

DESCRIPTION (provided by applicant): Terminal differentiation of erythroid cells is associated with generalized heterochromatinization and gene repression, reflected in decreased nuclear size and visibly more compact chromatin structure as red cells mature prior to enucleation. In the midst of this repressive environment, however, high-level expression of a select group of genes - especially the ?- and ?-globins - must be established and maintained. The mechanisms by which this is accomplished represent a basic question with implications both for studies of tissue-specific gene regulation and for clinical gene therapies, in which transgene expression must similarly be maintained in differentiating cells. Abundant evidence has been presented to establish the role of covalent histone modifications, such as acetylation, in the process of gene activation. For the most part, histone hyperacetylation is confined to promoter-proximal regions, where it presumably contributes to chromatin decondensation, relaxation of histone-DNA interactions, and stabilization of transcription factor interactions. At certain genes, however, histone hyperacetylation extends across much broader regions. In erythroid cells, the ?- and ?-globin loci exhibit such "domains" of hyperacetylation, and we have characterized several additional erythroid-specific gene loci that have them as well. Our results, along with studies of other gene loci, suggest that such domains are a crucial feature of their activation, and that they reflect the activity of distal enhancer elements required for high-level expression. As yet, however, the mechanisms by which such domains are formed, and the precise role they play in gene expression during terminal differentiation, are unknown. We propose to characterize cis-acting DNA sequences required for domain formation at the p-globin and other loci in erythroid cells, and eventually to identify the trans-acting factors that bind to these sequences and mediate domain formation. In this way, we will establish systems that can be used to elucidate the formation and function of hyperacetylated domains. Public Health Statement: This research, while highly basic in nature, is designed to elucidate mechanisms that underlie gene expression during terminal cellular differentiation. As such, it has relevance to disorders in which tissue-specific gene expression is disrupted - which include a number of cancers - as well as gene therapy approaches involving stable transgene expression in specific cell types.

描述（由申请人提供）：红细胞的终末分化与普遍的异染色质化和基因抑制相关，反映在随着红细胞在去核之前成熟，核尺寸减小且染色质结构明显更紧凑。然而，在这种压抑的环境中，必须建立并维持一组选定基因（尤其是α-和β-珠蛋白）的高水平表达。实现这一点的机制代表了一个基本问题，对组织特异性基因调控研究和临床基因治疗都有影响，其中转基因表达必须类似地在分化细胞中维持。已有大量证据证明共价组蛋白修饰（例如乙酰化）在基因激活过程中的作用。在大多数情况下，组蛋白过度乙酰化仅限于启动子近端区域，可能有助于染色质解缩、组蛋白-DNA 相互作用的松弛以及转录因子相互作用的稳定。然而，在某些基因上，组蛋白过度乙酰化会延伸到更广泛的区域。在红系细胞中，α-和β-珠蛋白基因座表现出这种超乙酰化“结构域”，并且我们已经表征了几个也具有它们的其他红系特异性基因位点。我们的结果以及对其他基因位点的研究表明，这些结构域是其激活的关键特征，并且它们反映了高水平表达所需的远端增强子元件的活性。然而，迄今为止，这些结构域的形成机制以及它们在终末分化过程中基因表达中发挥的确切作用尚不清楚。我们建议表征红细胞中p-珠蛋白和其他位点形成结构域所需的顺式作用DNA序列，并最终鉴定与这些序列结合并介导结构域形成的反式作用因子。通过这种方式，我们将建立可用于阐明超乙酰化结构域的形成和功能的系统。公共卫生声明：这项研究虽然本质上是非常基础的，但旨在阐明细胞终末分化过程中基因表达的机制。因此，它与组织特异性基因表达被破坏的疾病（包括多种癌症）以及涉及特定细胞类型中稳定转基因表达的基因治疗方法相关。