Essential functions of Fibulin proteins in outflow tract morphogenesis.

项目摘要 先天性心脏病（CHD）是人类最常见的出生缺陷， 缺陷占这一群体的20%。脑室远端畸形，漏斗， 和大动脉近端导致圆锥动脉干异常。具体实例包括 大血管转位、右心室双出口和法洛四联症。此外，相比之下 与其他类型的CHD相比，圆锥动脉干缺陷更常与遗传和综合征相关。 异常在这一患者队列中，17%的死亡率表明迫切需要改善我们的治疗。 了解早期发育线索指导这些畸变的流出道（OFT）形态发生。 这个应用程序的目的是揭示分子和细胞的机制，占中断 在OFT发育中的作用和人类圆锥动脉干CHD的基础。我们鉴定了Fibulin（Fbln）蛋白作为新的 OFT形态发生所必需的细胞外基质（ECM）调节剂。我们的初步数据显示 Fblns是平滑肌加入OFT和TGF-β信号传导所必需的， 动脉极的祖细胞。在目标1中，我将剖析细胞和分子机制 在OFT生长期间由fbln基因介导。我将评估前SHF祖细胞群的增殖 在Fbln功能丧失模型中，并评估心肌细胞、内皮细胞和血管内皮细胞的分化和增殖。 细胞和平滑肌细胞对动脉极处的前SHF衍生谱系的贡献。我会雇佣埃杜 细胞凋亡和发育定时测定来剖析Fbln基因的这些细胞类型特异性功能。在Aim中 2、检测pSmad 3在心肌细胞、内皮细胞和平滑肌细胞中的表达。 Fbln功能丧失胚胎的OFT。此外，我将进行功能获得和功能丧失实验 使用组成型活性Alk 5转基因和Smad 3磷酸化的小分子抑制剂， 分别这些策略将阐明Fbln蛋白如何通过TGF-β信号传导介导OFT发展。 从这些拟议的研究中获得的见解将阐明动脉粥样硬化的机制。 动脉极的顺应性和弹性变形与涉及动脉狭窄的疾病的关系 主动脉瓣和肺动脉瓣。此外，探索Fbln蛋白的细胞类型特异性作用将增强我们的研究。 能够识别新的治疗靶点和OFT导管和人工血管的组织工程方案 阀门.

PROJECT SUMMARY Congenital heart disease (CHD) is the most common birth defect in humans and patients with conotruncal defects comprise 20% of this population. Malformations of the distal aspect of the ventricle, the infundibulum, and the proximal aspect of the great arteries lead to conotruncal anomalies. Specific examples include transposition of the great vessels, double outlet right ventricle, and Tetralogy of Fallot. Moreover, in comparison to other types of CHDs, conotruncal defects are more frequently associated with genetic and syndromic abnormalities. Among this patient cohort, the mortality rate of 17% indicates a dire need for improvement in our understanding of the early developmental cues guiding these aberrations in outflow tract (OFT) morphogenesis. The purpose of this application is to uncover the molecular and cellular mechanisms that account for disruptions in OFT development and underlie human conotruncal CHDs. We identified Fibulin (Fbln) proteins as novel regulators of the extracellular matrix (ECM) essential for OFT morphogenesis. Our preliminary data demonstrate that Fblns are required for smooth muscle addition to the OFT and for TGF-β signaling in the late-differentiating progenitors that contribute to the arterial pole. In Aim 1, I will dissect the cellular and molecular mechanisms mediated by fbln genes during OFT growth. I will assess proliferation of the anterior SHF progenitor population in the Fbln loss-of-function model and evaluate differentiation and proliferation of the cardiomyocyte, endothelial cell, and smooth muscle cell contribution to anterior SHF-derived lineages at the arterial pole. I will employ EdU, apoptosis, and developmental timing assays to dissect these cell type-specific functions of Fbln genes. In Aim 2, I will probe cardiomyocyte, endothelial cell, and smooth muscle cell-type specific expression of pSmad3 in the OFT of Fbln loss-of-function embryos. Moreover, I will perform gain-of-function and loss-of-function experiments with a constitutively active Alk5 transgene and a small molecular inhibitor of Smad3 phosphorylation, respectively. These strategies will illuminate how Fbln proteins mediate OFT development via TGF-β signaling. Insights gained from these proposed studies will shed light on the mechanisms responsible for arterial compliance and elastic deformation at the arterial pole with implications for diseases involving stenosis of the aortic and pulmonary valves. Furthermore, probing the cell type-specific roles of Fbln proteins will augment our ability to identify novel therapeutic targets and protocols for tissue engineering of OFT conduits and artificial valves.