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

摘要 尽管目前的护理标准，但心力衰竭（HF）的诊断与生活质量差相关， 5-年死亡率接近50%。鉴于这一迫切的未满足的需求， 参与HF发病机制的研究有望为这种流行和致命的疾病找到新的治疗方法。 本申请的PI首次阐明了乙酰赖氨酸保守家族的关键作用 “阅读器”蛋白（BET布罗莫结构域）在HF的转录控制中的作用。重要的是，这些研究 利用了JQ 1的使用，JQ 1是BET溴结构域的一流的特异性小分子抑制剂。这种多PI 更新申请旨在垂直推进我们对异常染色质依赖性信号 转导（通过BET家族成员BRD 4）驱动病理性心脏纤维化。我们长远的目标是 开发BRD 4抑制作为HF的新治疗策略。令人兴奋的初步研究表明， BRD 4在体外介导心脏成纤维细胞活化，并且用JQ 1抑制BRD 4抑制心脏成纤维细胞活化。 在HF小鼠模型中的纤维化。从机制上讲，我们证明了BRD 4在亲- 通过与驱动肌成纤维细胞基因程序的调节增强子结合的纤维化TGF-β信号传导 （myoFB）激活。该提案将测试BRD 4作为节点功能的中心假设， 在一些实施方案中，本发明涉及可以在体内靶向的病理性心脏纤维化的转录调节因子。指导 通过强有力的初步数据，这一假设将通过追求三个强有力的具体目标来检验：（1）发现 BRD 4在体内心脏myoFB中的基因特异性作用;（2）分析染色质依赖性信号转导 调节内源性心脏myoFB的BRD 4依赖性激活的机制;（3）定义 在控制心脏myoFB激活中的特异性BRD 4功能结构域。一些创新的工具， 在第一个供资期内开发的技术将用于推进这一新的调查途径， 包括floxed Brd 4小鼠、Brd 4 -3XFLAG敲入小鼠、Brd 4布罗莫结构域敲入小鼠，以及 肽和小分子，选择性抑制BRD 4中的不同功能结构域。拟议 这项研究是重要的，因为它将促进开发药理学BRD 4抑制作为一种新的 因此，它解决了巨大的未满足的临床需求。我们的建议是高度 创新，因为我们成功地“药物”促纤维化转录和重塑通过前所未有的 方法，我们首次定义了心脏成纤维细胞中BRD 4的功能，并首次提供了 心脏成纤维细胞的表观基因组学评价。鉴于我们联盟的协同专业知识，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.