Chromatin Remodeling During Liver Development

肝脏发育过程中的染色质重塑

• 批准号: 7146597
• 负责人: Lisa A Cirillo
• 金额: $ 27.95万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-10 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7146597
• 关键词: cell differentiation; chromatin; developmental genetics; gene expression; genetic enhancer element; genetic regulation; genetic transcription; histogenesis; histones; laboratory rat; liver cells; molecular assembly /self assembly; protein binding; protein protein interaction; transcription factor

DESCRIPTION (provided by applicant): My goal is to determine how "pioneer" or initial chromatin binding transcription factors engage target sites in silent, compacted chromatin and promote entry of subsequent proteins. The pioneer transcription factor HNF3 binds to and activates numerous liver genes required for differentiation and metabolism. Previous studies have shown that HNF3 engages specific sites in chromatin in undifferentiated endoderm, prior to the activation of the albumin gene during liver specification. Using an in vitro system of reconstituted nucleosomes, I have demonstrated that HNF3 can bind its target sites within highly compacted chromatin packaging the albumin enhancer. This binding, and subsequent nucleosome positioning, creates a localized, open domain of chromatin accessible to other proteins. I hypothesize that chromatin binding and remodeling initiated by HNF3 establishes a chromatin environment that enables the subsequent binding, remodeling, and modification events required for albumin enhancer activation. I also propose that establishment of HNF3-mediated transcriptional competency is a prerequisite to the developmental activation of genes required for hepatocyte differentiation and function. In order to test these hypotheses, I will combine in vitro biochemical and in vivo-genetic approaches to address the following specific aims: 1) Does HNF3 displace linker histone from the albumin enhancer during chromatin opening? 2) Can HNF3-mediated chromatin remodeling activate the albumin enhancer in vivo? and 3) Is HNF3-mediated transcriptional competency essential for the activation of liver genes? These studies are designed to define the role played by pioneer DNA binding regulatory factors in the chromatin remodeling required for gene activation. Understanding how chromatin structural changes specify early gene regulatory events will provide insight into molecular mechanisms which underlie growth, development, and disease in humans. This primary goal of this grant is to determine the mechanisms used by the HNF3 protein to activate genes in the liver. HNF3 is essential for liver development, and is mutated in certain forms of cancer and diabetes. The results of the studies described in this grant will provide novel targets for the study and treatment of liver disease and neoplasia.

描述（由申请人提供）：我的目标是确定“先锋”或初始染色质结合转录因子如何参与沉默、压缩染色质中的靶位点并促进后续蛋白质的进入。先锋转录因子 HNF3 结合并激活分化和代谢所需的众多肝脏基因。先前的研究表明，在肝脏特化过程中白蛋白基因被激活之前，HNF3 会参与未分化内胚层染色质中的特定位点。使用体外重构核小体系统，我已经证明 HNF3 可以在高度压缩的染色质包装白蛋白增强剂中结合其靶位点。这种结合以及随后的核小体定位创建了其他蛋白质可接近的局部开放染色质结构域。我假设 HNF3 启动的染色质结合和重塑建立了一个染色质环境，该环境能够实现白蛋白增强子激活所需的后续结合、重塑和修饰事件。我还认为，HNF3 介导的转录能力的建立是肝细胞分化和功能所需基因发育激活的先决条件。为了检验这些假设，我将结合体外生化和体内遗传学方法来实现以下具体目标：1) HNF3 在染色质打开过程中是否会取代白蛋白增强子中的连接组蛋白？ 2) HNF3介导的染色质重塑能否在体内激活白蛋白增强子？ 3) HNF3 介导的转录能力对于肝基因的激活至关重要吗？这些研究旨在明确先锋 DNA 结合调节因子在基因激活所需的染色质重塑中所发挥的作用。了解染色质结构变化如何指定早期基因调控事件将有助于深入了解人类生长、发育和疾病的分子机制。 这笔资助的主要目标是确定 HNF3 蛋白激活肝脏基因的机制。 HNF3 对于肝脏发育至关重要，并且在某些形式的癌症和糖尿病中发生突变。该赠款中描述的研究结果将为肝病和肿瘤的研究和治疗提供新的靶标。