FGF Signaling Pathways and Craniofacial Development

描述（由申请人提供）：本提案的主要目的是确定由fgf启动的信号机制，这些信号机制是腭和中面部正常发育的基础。两种受体Fgfr1和Fgfr2的条件性缺失导致多发性颅面缺陷。尽管FGF信号已经在许多实验室（包括我们自己的实验室）从生化角度进行了广泛的研究，但对于这些信号通路如何调节颅面发育的形态发生过程知之甚少。在本申请中，我们提出：1。目的：探讨FGF信号在腭上皮中调控的通路。上皮中Fgfr2的缺失导致腭裂。为了确定这种缺陷背后的信号机制，我们将在Fgfr2位点生成并分析一系列条件信号小鼠突变体，这些突变体可以阻止单个或多个效应蛋白的结合。我们将进一步表征腭上皮中Fgfr2信号的转录靶点，并确定它们是否可以调节潜在间质的后续增殖。2. 探讨FGF信号在神经嵴中调控的通路。神经嵴Fgfr1缺失可导致多种颅面缺损，包括腭裂。为了确定潜在的信号机制，我们将在Fgfr1位点生成并表征一系列条件信号小鼠突变体，这些突变体可以阻止单个或多个效应蛋白的结合，靶向与Fgfr2相同的途径。由于上颚和其他颅面器官来源于背神经外胚层迁移的神经嵴细胞，我们还将进行基于Cre的谱系分析，以表征神经嵴细胞迁移的缺陷，这些缺陷是突变表型的基础。3. 识别和表征FGF调控的控制额鼻发育的通路。神经嵴细胞中Fgfr1和Fgfr2的联合缺失导致面部裂，并延伸至中线。建立

DESCRIPTION (provided by applicant): The major aims of this proposal are to identify signaling mechanisms initiated by FGFs that underlie normal development of the palate and the midface. Conditional deletion of the two receptors Fgfr1 and Fgfr2 lead to multiple craniofacial defects. Although FGF signaling has been extensively studied from a biochemical standpoint in many laboratories, including our own, remarkably little is known about how these signaling pathways regulate morphogenetic processes in craniofacial development. In this application, we propose: 1. To investigate the pathways regulated by FGF signaling in the palatal epithelium. Loss of Fgfr2 in the epithelium leads to a cleft palate. To establish the signaling mechanisms underlying this defect, we will generate and analyze an allelic series of conditional signaling mouse mutants at the Fgfr2 locus that prevent the binding of single or multiple effector proteins. We will further characterize transcriptional targets of Fgfr2 signaling in the palatal epithelium and determine if they can regulate subsequent proliferation of the underlying mesenchyme. 2. To investigate the pathways regulated by FGF signaling in the neural crest. Loss of Fgfr1 in the neural crest leads to multiple craniofacial defects, including in palate closure. To identify the underlying signaling mechanisms, we will generate and characterize an allelic series of conditional signaling mouse mutants at the Fgfr1 locus that prevent the binding of single or multiple effectors proteins, targeting the same pathways as for Fgfr2. Since the palate and other craniofacial organs are derived from neural crest cells migrated from dorsal neural ectoderm, we will also conduct Cre based lineage analysis to characterize defects in neural crest cell migration that underlie the mutant phenotypes. 3. To identify and characterize the FGF regulated pathways that control frontonasal development. Combined loss of both Fgfr1 and Fgfr2 in neural crest cells leads to facial clefting that extends through the midline. To establish the mechanistic basis for this phenotype, we will perform conditional mutagenesis in neural crest cells with compound Fgfr1 and Fgfr2 conditional mutants carrying point mutations for identical effectors, and compare these to the double null mutants. We will further establish the role of FGF signaling in midface development by conditional mutagenesis specifically in the frontonasal process. The proposed studies are anticipated to have a significant impact in craniofacial biology because they will establish the signaling mechanisms by which FGFs exert their action and open new directions for the prevention of craniofacial birth defects by the possible application of drug targets for critical FGF intracellular effectors.