Transcription cycle regulation by nutrients

项目摘要 非酒精性脂肪性肝病（NAFLD）是最常见的慢性肝病， 全球患病率为1/4。没有FDA批准的治疗方法可用。异常转录 基因表达的控制是代谢疾病的病理生理学的中心。RNA转录 聚合酶II（RNAP 2）通过几个协调步骤发生，其中包括前起始复合物 形成和起始、延伸和终止。基础转录机器的组装， 多年来，转录起始被认为是转录的限速和最重要的方面， 基因表达。最近的研究表明，从起始到伸长的过渡是一个限速过程， 这是一个关键步骤，需要特定的信号将RNAP 2从暂停状态释放出来，并参与转录 伸长率RNAP 2暂停释放是一种机制，允许快速和同步的基因表达， 对环境线索的反应，调整整个基因程序的表达。暂停-释放过程 需要在启动子近端区域的lys 9（H3 K9 ac）处的组蛋白H3乙酰化。H3 K9 ac水平 在小鼠中，通过高脂肪喂养显著改变，饮食诱导的肥胖、胰岛素抵抗和NAFLD模型。 我们假设RNAP 2的暂停释放是基因调控的基本机制， 养分有效性，在养分过剩的条件下，失调的暂停释放有助于 基因表达的异常变化。为了研究细胞如何在全基因组水平上对营养素做出反应，高- 将使用通量测序技术。本提案的目标将通过以下方式实现： （i）定义RNAP 2暂停释放在禁食至禁食的小鼠中转录调节中的作用， （ii）确定促脂肪生成转录因子甾醇 调节元件结合蛋白1（SREBP-1）有助于调节转录延伸;（iii） 确定H3 K9 ac如何在高脂肪条件下改变基因表达。这项建议是 意义重大，因为它将确定一个新的转录调控节点，为药物靶向开辟新的领域 的发现因此，该提案解决了代谢领域的一个基本科学空白， 这些创新的研究可能会导致新的和有效的治疗干预的发展， NAFLD、2型糖尿病和其他相关代谢疾病。

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.