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）：圆锥锥体畸形是严重的先天性心脏缺陷，需要在儿童早期进行手术。出生时患有这些缺陷的婴儿发病率和死亡率都很高。胚胎流出道（一个被定义为流出血管的区域，包括与心肌的连接处，称为动脉极）的异常发育会产生这些缺陷。神经嵴消融术可引起多种圆锥锥体畸形：直接影响包括流出道分隔缺失，间接影响包括流出道排列异常。在最近对鸡胚胎神经嵴消融模型的研究中，我们发现在咽部腹侧间充质中有一个次级心野（SHF），它提供成为心脏和平滑肌细胞的细胞，对动脉极的正常形成至关重要。在神经嵴消融模型中，来自SHF的心肌没有正确地加入到生长的动脉极中，导致颈干错位，并导致流出体分离失败。排列不齐的缺陷是一个组成部分的两个圆锥锥体畸形称为双出口右心室和法洛四联症。我们的初步结果表明，这些畸形是由于神经嵴消融后FGF信号的升高引起的，这是基于本实验室研究的四个证据：1)FGF靶基因在神经嵴消融后升高；2) FGF8最活跃的异构体Fgf8b升高；3) FGF报告细胞系在咽部腹侧表达FGF8b信号；4) FGF8b抗体在神经嵴消融的胚胎中恢复正常的环和挽救流出道的排列。这些初步数据支持了我们的总体假设，即动脉极的正常发育取决于心脏神经嵴细胞对咽部FGF8信号的调节。我们将检验具体假设：FGF8b升高通过影响二次心野心肌成分的增殖、迁移和/或分化导致异常动脉极发育（目的1）；神经嵴细胞通常通过吞噬FGF8蛋白和/或通过减少Fgf8b亚型的转录来抑制尾咽部的FGF8信号传导（目的2）。在目的1中，我们将把外植的SHF暴露于不同浓度的FGF8b中，并确定其对增殖、迁移、细胞死亡和分化的影响。我们将把表达FGF8b的质粒电穿孔到蛋胚的鸡咽内胚层，以将次级心脏场的发育事件与流出线排列联系起来。在目标2中，我们将（截断）