Chromatin Remodeling in Cardiovascular Development

描述（由申请人提供）： 心脏缺陷是最常见的先天性缺陷，也是心脏病的主要原因。通常，先天性心脏病在其进展的后期被诊断出来，此时治疗变得暂时并且具有显著的副作用。申请人的长期目标是建立一个独立的实验室，利用有关心脏发育的分子基础的发现来改进心脏病的诊断和治疗。在斯坦福大学博士后培训的剩余时间里，实验室管理、心血管生物学研究、实验室研究和手稿出版等课程将支持申请人向独立性的过渡。指导和独立的研究将集中在申请人的发现，即内皮细胞BAF染色质重塑复合物在两个心脏区域具有显着的特定作用。在心室中，BAF复合物通过抑制基质蛋白酶ADAMTS1的转录来决定肌细胞形态发生为小梁所需的细胞外基质。这种调节似乎是动态的，因为在发育后期ADAMTS1表达增加以防止过度小梁形成。在发育成瓣膜的内膜垫处，BAF复合物调节心内膜向间充质转化（EMT），该EMT引起内膜细胞增殖细胞。我推测，内皮素BAF复合物建立监管“开关”的关键位点，以控制心脏的不同区域的发育事件。在脑室，我建议的BAF复合物被招募到ADAMTS1通过特定的合作因素，以诱导核小体组织的动态变化，抑制转录。在垫子中，我假设BAF复合物调节Wnt信号传导的分泌调节因子的转录。在BAF复合物不存在的情况下，这些因子的错误表达诱导Wnt的过早和异位激活，从而阻断EMT。这些假设将使用两个特定目的来追求：1）确定微环境变化是否调节心室中的细胞信号传导。描述募集BAF复合物至ADAMTS1的顺式和反式作用因子。描述与BAF复合物合作抑制ADAMTS1的核小体修饰。2)确定抑制Wnt信号传导是否恢复缺乏内皮细胞BAF复合物的胚胎的EMT。描述Wnt调节转录本的表达，作为BAF复合物在内膜垫中的潜在靶点。

DESCRIPTION (provided by applicant): Hearts defects are the most common congenital defect and a major contributor to heart disease. Frequently, congenital heart diseases are diagnosed late in their progression, when treatments become temporary and have significant side effects. The applicant's long term goal is to establish an independent laboratory leveraging discoveries about the molecular basis of heart development into improved diagnostics and therapies for heart disease. During the remainder of his postdoctoral training at Stanford University, coursework in lab management, study of cardiovascular biology, laboratory research, and publication of manuscripts will support the applicant's transition to independency. Mentored and independent research will focus on the applicant's discovery that endocardial BAF chromatin remodeling complexes have remarkably specific roles in two heart regions. In the ventricles, the BAF complex determines the extracellular matrix required for morphogenesis of muscle cells into trabeculae by repressing transcription of a matrix protease, ADAMTS1. This regulation appears to be dynamic, as later in development ADAMTS1 expression increases to prevent excessive trabeculation. At the endocardial cushions that develop into valves, the BAF complex regulates an endocardial-to-mesenchymal transformation (EMT) that gives rise to cushion-populating cells. I hypothesize that endocardial BAF complexes establish regulatory "switches" at key loci to control developmental events in different regions of the heart. In the ventricles, I propose the BAF complex is recruited to ADAMTS1 by specific cooperating factors to induce dynamic changes in nucleosome organization to repress transcription. In the cushions, I hypothesize the BAF complex regulates transcription of secreted regulators of Wnt signaling. Misexpression of these factors in the absence of the BAF complex induces a premature and ectopic activation of Wnt that blocks EMT. These hypotheses will be pursued using two Specific Aims: 1) Determine if microenvironment changes regulate cell signaling in the ventricles. Describe cis-and Trans acting factors that recruit the BAF complex to ADAMTS1. Delineate nucleosome modifications that cooperate with the BAF complex to repress ADAMTS1. 2) Determine if inhibiting Wnt signaling restores EMT in embryos lacking endocardial BAF complexes. Describe the expression of Wnt regulating transcripts as potential targets of the BAF complex in endocardial cushions.