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，也是心脏病的主要诱因。通常，先天性心脏病的诊断是在病情进展较晚的时候进行的，那时治疗是暂时的，并有显著的副作用。申请者的长期目标是建立一个独立的实验室，利用关于心脏发育的分子基础的发现，改进心脏病的诊断和治疗。在斯坦福大学剩余的博士后培训期间，实验室管理、心血管生物学研究、实验室研究和手稿出版方面的课程将支持申请人向独立的过渡。有指导和独立的研究将集中在申请人的发现上，即心内膜BAF染色质重塑复合体在两个心脏区域具有显著的特定作用。在脑室中，BAF复合体通过抑制基质蛋白酶ADAMTS1的转录来确定肌肉细胞向小梁形态发生所需的细胞外基质。这一调节似乎是动态的，因为在发育后期，ADAMTS1的表达增加，以防止过度的小梁形成。在发育成瓣膜的心内膜垫上，BAF复合体调节心内膜到间充质的转化(EMT)，从而产生垫填充细胞。我假设心内膜BAF复合体在关键部位建立了调控“开关”，以控制心脏不同区域的发育事件。在脑室，我认为BAF复合体是由特定的协同因子招募到ADAMTS1上的，以诱导核小体组织的动态变化来抑制转录。在垫子上，我假设BAF复合体调节Wnt信号的分泌调节因子的转录。在没有BAF复合体的情况下，这些因子的错误表达会导致Wnt的过早和异位激活，从而阻断EMT。这些假说将通过两个特定的目标来实现：1)确定微环境变化是否调节脑室中的细胞信号。描述将BAF复合体招募到ADAMTS1的顺式和反式作用因素。描绘与BAF复合体合作抑制ADAMTS1的核小体修饰。2)确定抑制Wnt信号是否能恢复缺乏心内膜BAF复合体的胚胎的EMT。描述作为BAF复合体潜在靶点的Wnt调控转录本在心内膜垫中的表达。

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.