Neural Crest Modulates FGF Signaling in the Pharynx

神经嵴调节咽部 FGF 信号传导

• 批准号: 7287074
• 负责人: Margaret Loewy Kirby
• 金额: $ 3.99万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7287074
• 关键词: Neural; Crest; Modulates; FGF; Signaling

DESCRIPTION (provided by applicant): Conotruncal malformations are severe congenital cardiac defects that require surgery early in childhood. Infants born with these defects suffer from significant morbidity and mortality. Abnormal embryonic development of the outflow tract (a region defined as the outflow vessels including the junction with the myocardium, called the arterial pole) produces these defects. Neural crest ablation causes a wide variety of conotruncal malformations: direct effects include absence of outflow septation, and indirect effects are malalignment of the outflow tract. In recent studies of the neural crest ablation model in chick embryos, we have discovered a secondary heart field (SHF) in the ventral pharyngeal mesenchyme that provides cells that become cardiac and smooth muscle myocytes essential to the normal formation of the arterial pole. In the neural crest-ablation model, myocardium from SHF is not added properly to the growing arterial pole resulting in malalignment of the conotruncus in addition to failure of outflow septation. The malalignment defects are a component of two conotruncal malformations called double outlet right ventricle and tetralogy of Fallot. Our preliminary results indicate that these malformations are due to elevated FGF signaling after neural crest ablation based on four pieces of evidence from investigations performed in this laboratory: 1) FGF target genes are elevated after neural crest ablation; 2) Fgf8b, the most active isoform of FGF8 is elevated; 3) a reporter cell line for FGF registers elevated FGF8b signaling in the ventral pharynx; and 4) FGF8b antibody restores normal looping and rescues alignment of the outflow tract in neural crest-ablated embryos. These preliminary data support our overall hypothesis that normal development of the arterial pole depends on the regulation of FGF8 signaling in the pharynx by cardiac neural crest cells. We will test the specific hypotheses: that elevated FGF8b leads to abnormal arterial pole development by affecting proliferation, migration and/or differentiation of the myocardial component of the secondary heart field (aim 1); neural crest cells normally depress FGF8 signaling in the caudal pharynx by endocytosis of the FGF protein and/or by decreasing the transcription of the Fgf8b isoform (aim 2). In aim 1, we will expose explanted SHF to various concentrations of FGF8b and determine its effect on proliferation, migration, cell death and differentiation. We will electroporate an FGF8b expressing plasmid into the pharyngeal endoderm of chick embryos in ovo to correlate developmental events in the secondary heart field with outflow alignment. In aim 2, we will (truncated)

描述（由申请人提供）：骨膜畸形是严重的先天性心脏缺陷，需要在儿童早期进行手术。患有这些缺陷的婴儿患有明显的发病率和死亡率。流出道的异常胚胎发育（一个定义为与心肌连接在内的流出容器，称为动脉极）会产生这些缺陷。神经rest消融会引起多种构造畸形：直接影响包括缺乏流出分隔，间接影响是流出道的不满。在雏鸡胚胎中神经rest消融模型的最新研究中，我们在腹咽间质中发现了一个次级心脏场（SHF），该细胞提供的细胞成为心脏和平滑肌心肌细胞，对动脉极正常形成必不可少。在神经冠模型中，SHF的心肌未正确地添加到生长的动脉极中，而除了流出分离的失败外，还导致了孔子骨架不良。恶意缺陷是两个共骨畸形的组成部分，称为双插座右心室和法洛的四边形。我们的初步结果表明，这些畸形是由于基于在该实验室进行的研究的四个证据的神经rest消融后的FGF信号传导升高所致：1）神经crest消融后FGF靶基因升高。 2）FGF8B，FGF8最活跃的同工型升高； 3）FGF登记板的记者细胞系升高FGF8B信号传导； 4）FGF8B抗体恢复了神经crest驱动的胚胎中流出道的正常环路并挽救对齐。这些初步数据支持我们的总体假设，即动脉极的正常发育取决于心脏神经crest细胞在咽部中FGF8信号的调节。我们将检验特定的假设：升高的FGF8B通过影响次级心脏场的心肌成分的增殖，迁移和/或分化而导致动脉极发育异常（AIM 1）；神经rest细胞通常通过FGF蛋白的内吞作用和/或降低FGF8B同工型的转录（AIM 2）来降低尾咽中的FGF8信号传导。在AIM 1中，我们将使外植的SHF暴露于各种浓度的FGF8B，并确定其对增殖，迁移，细胞死亡和分化的影响。我们将在OVO中的小鸡胚胎的咽内胚层中进行电燃料，以将次级心脏场中的发育事件与流出比对相关联。在AIM 2中，我们将（截断）