FGF Signaling Pathways and Craniofacial Development

这项建议的主要目的是确定由FGFs启动的信号机制，这些机制是颅面部的基础。 形态发生。FGFR1受体和FGFR2在神经脊细胞中的丢失导致神经发育不全 面中部和下颌的多个组成部分，而FGFR1/2亚型突变会导致唇裂 味觉。在其他地方，FGFR2而不是FGFR1在唾液腺上皮细胞中起主导作用，其活性 受到不同配体的不同调控。成纤维细胞生长因子信号级联的参与导致细胞的二聚化 FGFRs、多个细胞内效应器的结合和汇聚的细胞反应的激活 ERK1/2和其他几条通路。此应用程序提供以下建议： 1.探讨成纤维细胞生长因子信号转导系统在面中部发育中的作用。FGFR1和FGFR2的综合损失 神经脊细胞导致面部裂隙延伸至正中线，面中部、下颌发育不全 鼻侧和上颌突发育不良，细胞明显死亡。确定…的原产地 这些面中部缺陷、FGFR1/2下颌和/或侧鼻/上颌突条件突变 研究FGFR1/2在下颌或侧面结构中的缺失是如何导致面部裂隙的。 此外，神经脊fgfr1/2突变体将与bim突变体杂交，以解除模式改变的关联。 BCL-2家族调控细胞死亡。 2.明确FGFR1和FGFR2在颅面发育中的信号转导机制。要确定 在先前产生的FGFR1和FGFR2等位基因突变系列中保持活跃的信号通路 阻止单个或多个效应蛋白的结合和特定信号通路的启动 将利用内源性表位在小鼠胚胎腭间充质细胞中进行蛋白质组筛选 标记FGFR1和FGFR2受体。在一种补充方法中，在小鼠体内添加额外的候选酪氨酸 被破坏的受体上的磷酸化位点就会产生。 3.研究配体同一性所决定的信号转导途径。成纤维细胞生长因子信号的一个新主题是 在多种生理环境中的细胞反应可以在配体的身份中编码，并且不仅 在受体的水平上指定。中由Fgf7和FGF10差异编码的信令响应 颌下腺分支的形态发生将被研究。关键的下游成纤维细胞生长因子途径 这一反应将通过每个配体刺激后的转录图谱进一步鉴定，以及 对ERK1/2和PI3K信号和反馈抑制通路敏感的形态发生反应将 被调查。 这些拟议的研究探索了生长因子信号转导在颅面生物学和 为预防头面部出生缺陷开辟新的方向。

The major aims of this proposal are to identify signaling mechanisms initiated by FGFs that underlie craniofacial morphogenesis. Loss of the FGFR1 receptor together with FGFR2 in neural crest cells leads to agenesis of multiple components of the midface and mandible, whereas hypomorphic mutations in Fgfr1/2 result in cleft palate. Elsewhere, FGFR2 rather than FGFR1 has a predominant role in salivary gland epithelia, and its activity is differentially regulated by various ligands. Engagement of the FGF signaling cascade leads to dimerization of the FGFRs, binding of multiple intracellular effectors and activation of cellular responses that converge on ERK1/2 and several other pathways. This application proposes: 1. To investigate how FGF signaling coordinates midface development. Combined loss of both Fgfr1 and Fgfr2 in neural crest cells leads to facial clefting that extends through the midline, agenesis of the midface, mandibular hypoplasia, and significant cell death in the lateral nasal and maxillary processes. To determine the origin of these midface defects, Fgfr1/2 mandibular and/or lateral nasal /maxillary process conditional mutants will be generated to investigate how loss of Fgfr1/2 in the mandible or lateral structures contributes to facial clefting. Furthermore, neural crest Fgfr1/2 mutants will be crossed to Bim mutants to disassociate alterations in patterning from BCL-2 family regulated cell death. 2. To identify signaling mechanisms promoted by Fgfr1 and Fgfr2 in craniofacial development. To identify signaling pathways that remain active in a previously generated Fgfr1 and Fgfr2 allelic series of point mutations that prevent the binding of single or multiple effector proteins and the initiation of specific signaling pathways, a proteomic screen will be performed in mouse embryonic palatal mesenchyme cells using endogenous epitope tagged FGFR1 and FGFR2 receptors. In a complementary approach, mice in which additional candidate tyrosine phosphorylation sites are disrupted on the receptors will be generated. 3. To characterize signaling pathways specified by ligand identity. An emerging theme in FGF signaling is that cellular responses in multiple physiological contexts can be encoded in the identity of the ligand and are not only specified at the level of the receptor. Signaling responses that are differentially encoded by FGF7 and FGF10 in submandibular salivary gland branching morphogenesis will be investigated. Critical downstream FGF pathways in this response will be further identified by transcriptional profiling following stimulation with each ligand, and morphogenetic responses that are sensitive to ERK1/2 and PI3K signaling and feedback inhibition pathways will be investigated. These proposed studies explore novel territories in the area of growth factor signaling in craniofacial biology and open new directions for the prevention of craniofacial birth defects.