Impacts of transcription elongation on cardiac gene regulation during homeostasis and regeneration

项目摘要 在美国，心力衰竭是死亡的主要原因，这给医疗保健带来了巨大的负担 每一年都是这样。尽管心力衰竭的原因是不同的，但心脏经历了基因 在失败过程中，表达发生变化，从而导致结构和功能缺陷。我们的长期目标是 了解维持心脏结构和功能的转录调控机制 动态平衡，可诱导心脏保护作用或促进损伤后的心脏修复。 在本申请中，我们将使用转录调控因子Rtf1作为切入点来解决这一关键问题 在心脏生物学方面。 转录延伸在细胞RNA生物发生中的关键作用近年来受到越来越多的关注 但它们如何有助于维持心脏内稳态，以及如何调节转录 延长术可能会促进受损心脏的修复，但仍难以捉摸。同时使用斑马鱼和老鼠 遗传学方面，我们之前已经证明Rtf1的活性对心肌发育是必不可少的。RTF1耗尽 破坏RNA POL II启动子近端的停顿，阻断心肌基因程序的激活，并 防止心肌祖细胞的形成，导致无情的胚胎。在初步数据中导致 这一建议，我们发现，Rtf1在正常和应激的成人心脏中发挥着重要作用。烧蚀 成人心肌细胞中Rtf1活性导致心脏基因表达异常导致快速心力衰竭 以及收缩能力的丧失。在应激心脏中，我们观察到心肌细胞内Rtf1表达增加 损伤后，提示Rtf1在心脏应激反应中发挥作用。Rtf1的过度表达也促进了 斑马鱼脑室切除模型中的心肌细胞增殖。心脏基因的失调 Rtf1缺陷衰竭心脏中活化转录的表观遗传标志的表达和减少 Rtf1是心肌细胞的关键转录调节因子。这些发现导致了我们的中央 假设Rtf1调节转录暂停和共转录的组蛋白修饰以促进 在心肌细胞中有效地合成mRNA，从而维持正常心脏的结构和功能 和紧张的心脏。我们描绘了三个目标来质疑这一假说。具体来说，我们将 研究Rtf1依赖的基因在心肌细胞中的表达并破译其进展分子， 在心力衰竭期间发生的细胞、生理和代谢变化(目标1)。我们将使用数组 揭示Rtf1影响转录组的分子基础的分子方法 心肌细胞(目标2)。我们还将研究Rtf1如何对心脏损伤做出反应，以及 操纵Rtf1活性以促进心脏修复(目标3)。实现这些目标不仅将提供 对心脏基因表达调控网络的重大新见解也可能成为一种治疗方法 目标是促进心脏健康和损伤后修复。

Project Summary Heart failure is a major cause of death in the US, contributing significantly to the burden of the healthcare system every year. Despite the heterogeneity of the causes of heart failure, the heart undergoes gene expression changes during failure resulting in structural and functional defects. Our long-term goal is to understand the transcriptional regulatory mechanisms that sustain the structure and function of the heart in homeostasis and that can induce cardiac protective effects or promote cardiac repair upon injury. In this application, we will use the transcription regulator Rtf1 as a point of entry to address this critical question in cardiac biology. Critical roles for transcription elongation in cellular RNA biogenesis have gained increasing attention in recent years, but how they contribute to the maintenance of cardiac homeostasis and how modulating transcription elongation might promote cardiac repair in damaged hearts remain elusive. Using both zebrafish and mouse genetics, we have previously shown that Rtf1 activity is essential for myocardial development. Rtf1 depletion destabilizes promoter-proximal pausing of RNA Pol II, blocks activation of the myocardial gene program and prevents myocardial progenitor cell formation resulting in a heartless embryo. In preliminary data leading to this proposal, we have found that Rtf1 plays important roles in normal and stressed adult hearts. Ablation of Rtf1 activity in adult cardiomyocytes leads to rapid heart failure with dysregulated cardiac gene expression and a loss of contractility. In stressed hearts, we observed elevated Rtf1 expression within cardiomyocytes after injury, suggesting a role for Rtf1 in the cardiac stress response. Overexpression of Rtf1 also promotes cardiomyocyte proliferation in a zebrafish ventricular resection model. The dysregulated cardiac gene expression and reduction of epigenetic marks of active transcription in Rtf1-deficient failing hearts suggest that Rtf1 functions as a key transcriptional regulator for cardiomyocytes. These findings lead to our central hypothesis that Rtf1 modulates transcriptional pausing and co-transcriptional histone modification to facilitate efficient mRNA synthesis in cardiomyocytes and thereby sustains cardiac structure and function in normal and stressed hearts. We have delineated three Aims to interrogate this hypothesis. Specifically, we will investigate Rtf1-dependent gene expression in cardiomyocytes and decipher the progressive molecular, cellular, physiological and metabolomic changes occurring during heart failure (Aim 1). We will use an array of molecular approaches to uncover the molecular basis by which Rtf1 impacts the transcriptome in cardiomyocytes (Aim 2). We will also investigate how Rtf1 responds to cardiac damage and the potential of manipulating Rtf1 activity to promote cardiac repair (Aim 3). Accomplishing these aims will not only provide significant new insights into the regulatory network of cardiac gene expression but also a possible therapeutic target to promote cardiac health and post-injury repair.