Transcription cycle regulation by nutrients

项目总结 非酒精性脂肪性肝病(NAFLD)是最常见的慢性肝病，据估计 全球患病率为每4人中就有1人。目前还没有FDA批准的治疗方法。异常转录 基因表达的控制是代谢性疾病的病理生理学的核心。RNA转录 聚合酶II(RNAP2)通过几个相互协调的步骤发生，其中包括前起始复合体 形成和启动、延伸和终止。基本转录机器的组装和 多年来，转录启动被认为是速度限制和最重要的驱动因素 基因表达。最近的研究表明，从起始到伸长的转变是一个速度限制 和关键步骤，需要特定的信号将RNAP2从暂停状态释放出来并参与转录 伸长率。RNAP2暂停释放是一种允许快速和同步表达基因的机制 对环境提示做出反应，调整整个基因程序的表达。暂停-释放的过程 启动子近端的组蛋白H3K9ac需要组蛋白H3乙酰化。H3K9ac水平为 高脂饮食显著改变了小鼠的肥胖、胰岛素抵抗和非酒精性脂肪肝的模型。 我们假设RNAP2的暂停释放是基因调控的一个基本机制 养分的有效性，以及在养分过剩的情况下，错误的暂停释放有助于 基因表达的异常变化。为了在全基因组水平上研究细胞对营养物质的反应， 将使用吞吐量测序技术。这项提案的目标将通过以下方式实现 具体目的如下：(I)确定RNAP2暂停释放在空腹TO细胞转录调控中的作用 REED转换；(Ii)确定促脂肪生成转录因子斯特罗尔的机制 调节元件结合蛋白1(SREBP-1)参与调节转录延伸； 确定H3K9ac如何在高脂肪条件下改变基因表达。这项建议是 意义重大，因为它将识别一个新的转录调控节点，为药物靶点开辟新的天地 发现号。因此，这项建议解决了新陈代谢领域的一个基本科学空白，以及 这些创新的研究可能导致开发新的有效的治疗干预措施 非酒精性脂肪肝、2型糖尿病和其他相关代谢性疾病。

PROJECT SUMMARY Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, with an estimated global prevalence of 1 in 4 individuals. No FDA-approved treatments are available. Aberrant transcriptional control of gene expression is central to the pathophysiology of metabolic diseases. Transcription by RNA Polymerase II (RNAP2) occurs through several coordinated steps, which include pre-initiation complex formation and initiation, elongation, and termination. The assembly of the basal transcription machinery and transcription initiation was believed for many years to be the rate-limiting and most important aspect driving gene expression. Recent research has revealed that the transition from initiation to elongation is a rate-limiting and critical step, requiring specific signals to release RNAP2 from its paused state and engage in transcription elongation. RNAP2 pause-release is a mechanism that allows fast and synchronized gene expression in response to environmental cues, adjusting expression of entire gene programs. The process of pause-release requires histone H3 acetylation at lys9 (H3K9ac) in the promoter-proximal region. H3K9ac levels are significantly altered by high-fat feeding in mice, a model of diet-induced obesity, insulin resistance and NAFLD. We hypothesize that RNAP2 pause-release is a fundamental mechanism of gene regulation in response to nutrient availability, and under conditions of nutrient excess, misregulated pause-release contributes to aberrant changes in gene expression. To study how cells respond to nutrients at the genome-wide level, high- throughput sequencing technologies will be used. The goals of this proposal will be achieved by pursuing the following specific aims: (i) Define the role of RNAP2 pause-release in transcription regulation in the fasted to refed transition; (ii) Determine the mechanism by which the pro-lipogenesis transcription factor Sterol Regulatory Element Binding Protein 1 (SREBP-1) contributes to regulate transcription elongation; (iii) Determine how H3K9ac contributes to change gene expression under high-fat conditions. This proposal is significant because it will identify a novel node of transcription regulation, breaking new ground for drug target discovery. Thus, this proposal addresses a basic scientific gap in the field of metabolism, and the results of these innovative studies could lead to the development of new and effective therapeutic interventions for NAFLD, type 2 diabetes and other associated metabolic diseases.