Regulation of Chromatin Signaling in Heart Failure by the BRD4 Bromodomain Protein.

摘要 尽管目前的护理标准，心力衰竭(HF)的诊断与较低的生活质量和 5年死亡率接近50%。鉴于这一迫切的未得到满足的需求，阐明新的机制 参与心力衰竭的发病机制有望为这种流行和致命的疾病找到新的治疗方法。 这一应用的PI首次阐明了保守的乙酰赖氨酸家族的关键作用 Hf转录调控中的“读者”蛋白(BET溴域)。重要的是，这些研究 利用JQ1，一种一流的BET溴域的特定小分子抑制剂。这是多路PI 更新应用程序寻求垂直推进我们对异常染色质依赖信号如何 转导(通过BET家族成员BRD4)驱动病理性心肌纤维化。我们的长期目标是 目的：开发BRD4抑制治疗心力衰竭的新策略。令人振奋的初步研究表明 BRD4在体外介导心脏成纤维细胞活化，JQ1抑制BRD4抑制心脏 心衰小鼠模型中的纤维化。从机制上，我们证明了BRD4在PRO下游的功能。 通过与驱动肌成纤维细胞基因程序的调节增强子结合来传递纤维化转化生长因子-信号 (MyoFB)激活。这一提议将检验BRD4作为节点发挥作用的中心假设 病理性心肌纤维化的转录调节因子，可在体内进行药理学靶向。引导式 通过强大的初步数据，这一假设将通过追求三个稳健的具体目标来检验：(1)发现 BRD4在活体心肌myoFB中的基因特异性作用；(2)剖析染色质依赖的信号转导 调控BRD4依赖的内源性心肌肌纤维蛋白原激活的机制；(3)确定 特异性BRD4功能结构域在控制心肌myoFB激活中的作用。几个创新的工具是 将利用在第一个资助期内制定的方案来推进这一新的调查途径， 包括Brd4小鼠、Brd4-3XFLAG敲入小鼠、Brd4溴结构域敲入小鼠以及 选择性抑制BRD4中不同功能结构域的多肽和小分子。建议数 这项研究具有重要意义，因为它将促进药理学BRD4抑制作为一种新的 治疗策略，因此解决了一个巨大的未得到满足的临床需求。我们的建议是高度 创新是因为我们成功地通过史无前例的药物促进了肝纤维化的转录和重塑 首次明确了BRD4在心脏成纤维细胞中的功能，并首次提出了BRD4在心脏成纤维细胞中的作用。 心脏成纤维细胞的表观基因组学评价。鉴于我们财团的协同专业知识，我们设想 我们高度合作的团队的持续贡献将为小说的发展铺平道路 心血管疾病的“表观遗传疗法”。

Abstract Despite current standard of care, a diagnosis of heart failure (HF) is associated with poor quality-of-life and a 5-year mortality approaching 50%. In light of this urgent unmet need, the elucidation of novel mechanisms involved in HF pathogenesis holds promise for identifying new therapies for this prevalent and deadly disease. The PIs of this application were the first to illustrate a crucial role for a conserved family of acetyl-lysine “reader” proteins (BET bromodomains) in the transcriptional control of HF. Importantly, these studies leveraged the use of JQ1, a first-in-class, specific small molecule inhibitor of BET bromodomains. This multi-PI renewal application seeks to vertically advance our understanding of how aberrant chromatin-dependent signal transduction (via the BET family member BRD4) drives pathologic cardiac fibrosis. Our long-term objective is to develop BRD4 inhibition as a novel therapeutic strategy in HF. Exciting preliminary studies demonstrate that BRD4 mediates cardiac fibroblast activation in vitro, and that BRD4 inhibition with JQ1 suppresses cardiac fibrosis in mouse models of HF. Mechanistically, we demonstrate that BRD4 functions downstream of pro- fibrotic TGF- signaling by binding to regulatory enhancers that drive a gene program of myofibroblast (myoFB) activation. This proposal will test the central hypothesis that BRD4 functions as a nodal transcriptional regulator of pathological cardiac fibrosis that can be pharmacologically targeted in vivo. Guided by strong preliminary data, this hypothesis will be tested by pursuing three robust specific aims: (1) Discover the gene-specific role of BRD4 in cardiac myoFB in vivo; (2) Dissect the chromatin-dependent signaling mechanisms governing BRD4-dependent activation of endogenous cardiac myoFBs; (3) Define the roles of specific BRD4 functional domains in the control of cardiac myoFB activation. Several innovative tools that were developed during the first funding period will be employed to advance this new avenue of investigation, including floxed Brd4 mice, Brd4-3XFLAG knock-in mice, Brd4 bromodomain knock-in mice, as well as peptides and small molecules that selectively inhibit distinct functional domains in BRD4. The proposed research is significant because it will facilitate development of pharmacologic BRD4 inhibition as a novel therapeutic strategy in HF, and therefore addresses an enormous unmet clinical need. Our proposal is highly innovative because we successfully “drug” pro-fibrotic transcription and remodeling via unprecedented approaches, we define the functions of BRD4 in cardiac fibroblasts for the first time, and we provide the first epigenomic evaluation of cardiac fibroblasts. Given the synergistic expertise of our consortium, we envision that sustained contributions from our highly-collaborative group will pave the way for the development of novel “epigenetic therapies” for cardiovascular disease.