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

项目摘要 心力衰竭是美国死亡的主要原因，显著增加了医疗保健的负担 系统每年。尽管心力衰竭的原因是异质性的，但心脏经历了基因突变。 在失败期间表达改变导致结构和功能缺陷。我们的长期目标是 理解维持心脏结构和功能的转录调控机制， 体内平衡，并且可以诱导心脏保护作用或促进损伤后的心脏修复。 在本申请中，我们将使用转录调节因子Rtf1作为切入点来解决这一关键问题 心脏生物学 转录延长在细胞RNA生物合成中的重要作用近年来受到越来越多的关注 但是它们如何有助于维持心脏稳态以及如何调节转录 延长可能促进受损心脏的心脏修复仍然是难以捉摸的。用斑马鱼和老鼠 遗传学，我们以前已经表明Rtf1活性是心肌发育所必需的。rtf1缺失 使RNA Pol II的启动子近端暂停不稳定，阻断心肌基因程序的激活， 阻止心肌祖细胞形成，导致无心胚胎。初步数据显示， 根据这一提议，我们发现Rtf1在正常和应激的成人心脏中起重要作用。消融 成年心肌细胞中rtf1活性导致快速心力衰竭并伴有心脏基因表达失调 以及收缩力的丧失。在应激的心脏中，我们观察到心肌细胞中Rtf1的表达升高， 损伤后，提示Rtf1在心脏应激反应中的作用。Rtf1的过度表达也促进了 斑马鱼心室切除模型中的心肌细胞增殖。心脏基因失调 在Rtf1缺陷的衰竭心脏中，表观遗传标记的表达和减少表明， Rtf1是心肌细胞的关键转录调节因子。这些发现导致我们的中央 假设Rtf1调节转录暂停和共转录组蛋白修饰， 在心肌细胞中有效的mRNA合成，从而维持正常的心脏结构和功能。 心有压强。我们提出了三个目标来质疑这一假设。具体来说，我们将 研究心肌细胞中Rtf1依赖性基因的表达， 心力衰竭期间发生的细胞、生理和代谢组学变化（目标1）。我们将使用数组 的分子方法来揭示Rtf1影响转录组的分子基础， 心肌细胞（Aim 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（目的3）。实现这些目标不仅将提供 这是对心脏基因表达调控网络的重要新见解，也是一种可能的治疗方法。 以促进心脏健康和损伤后修复为目标。

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.