HNF-4 and coactivators in apoAl gene regulation

HNF-4 和 apoAl 基因调控中的共激活因子

• 批准号: 6836453
• 负责人: SOHAIL MALIK
• 金额: $ 35.69万
• 依托单位: ROCKEFELLER UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6836453
• 关键词: DNA directed RNA polymerase; apolipoproteins; cell free system; chromatin; chromatin immunoprecipitation; cofactor; genetic enhancer element; genetic regulation; genetic transcription; high density lipoproteins; laboratory rabbit; liver cells; nuclear receptors; protein binding; protein protein interaction; transcription factor

DESCRIPTION (provided by applicant): This proposal aims to obtain a detailed molecular understanding of how the gene for apolipoprotein AI (apoAI) is transcriptionally regulated in liver cells. ApoAI is the major protein component of high-density lipoprotein, HDL, whose plasma levels are inversely correlated with atherosclerosis, a leading cause of mortality and morbidity in developed countries. An aim of the project is also to understand the mechanism by which the orphan nuclear receptor HNF-4, previously implicated in apoAI transcriptional control, activates transcription by RNA polymerase II. In addition to apoAI, HNF-4 regulates many genes involved in the "metabolic syndrome" [including hypertension and non-insulin dependent diabetes mellitus (NIDDM)]. Also, its gene was independently isolated as the causative factor for maturity onset diabetes of the young (MODY1). Furthermore, HNF-4 is a major transcription factor for hepatitis B viral gene expression, an etiologic agent for liver cancer. The project is therefore expected to have broad relevance. Cellular and in vitro methods will be employed to identify transcription factors that are required for HNF-4-mediated activation at the liver-specific enhancer of the apoAI gene. Transcription factors under study will include another liver-enriched factor, HNF-3 (known to synergistically function with HNF-4), Mediator (the global coactivator recently shown to be necessary for HNF-4 function) and key chromatin cofactors (histone acetyl transferases, ATP-remodeling). Cellular analyses (chromatin immunoprecipitation [ChIP]) will delineate transcription factor interactions in living cells. Both steady-state expression of the apoAI gene in mature hepatocytes, as well as the pathway leading to the initial onset of apoAI gene expression in developing mouse embryoid bodies (in culture) will be monitored. In vitro approaches will complement these in vivo studies. Thus, functional (in vitro transcription from chromatin templates to recapitulate core features of apoAI gene regulation) and structural (protein-protein and protein-DNA interactions) analyses will also be undertaken. Together, the proposed studies will permit understanding of the mechanistic basis for the synergistic function of the relevant transcription factors, which regulate apoAI gene expression in vivo and contribute to its homeostasis. They will also potentially reveal targets for future therapeutic developments in the metabolic and cardiovascular areas.

描述（由申请人提供）：该提案旨在详细了解载脂蛋白 AI (apoAI) 基因如何在肝细胞中进行转录调控。 ApoAI 是高密度脂蛋白 HDL 的主要蛋白质成分，其血浆水平与动脉粥样硬化呈负相关，动脉粥样硬化是发达国家死亡和发病的主要原因。该项目的另一个目的是了解孤儿核受体 HNF-4（之前参与 apoAI 转录控制）通过 RNA 聚合酶 II 激活转录的机制。除了 apoAI 之外，HNF-4 还调节许多与“代谢综合征”[包括高血压和非胰岛素依赖型糖尿病 (NIDDM)] 相关的基因。此外，其基因被独立分离为青少年发病型糖尿病（MODY1）的致病因素。此外，HNF-4 是乙型肝炎病毒基因表达的主要转录因子，乙型肝炎病毒基因表达是肝癌的病因。因此，该项目预计具有广泛的相关性。将采用细胞和体外方法来鉴定 HNF-4 介导的 apoAI 基因肝脏特异性增强子激活所需的转录因子。正在研究的转录因子将包括另一种肝脏富集因子 HNF-3（已知与 HNF-4 具有协同作用）、介导因子（最近显示 HNF-4 功能所必需的全局共激活因子）和关键染色质辅助因子（组蛋白乙酰转移酶） ，ATP 重塑）。细胞分析（染色质免疫沉淀 [ChIP]）将描述活细胞中转录因子的相互作用。将监测成熟肝细胞中 apoAI 基因的稳态表达，以及导致发育中的小鼠胚状体（培养中）中 apoAI 基因表达初始开始的途径。体外方法将补充这些体内研究。因此，还将进行功能（从染色质模板进行体外转录以概括 apoAI 基因调控的核心特征）和结构（蛋白质-蛋白质和蛋白质-DNA 相互作用）分析。总之，拟议的研究将有助于了解相关转录因子协同功能的机制基础，这些转录因子在体内调节 apoAI 基因表达并有助于其稳态。他们还将有可能揭示代谢和心血管领域未来治疗发展的目标。