Jagged-Notch and Fgf signaling: patterning the vertebrate upper face

描述(申请人提供)：颅面畸形是人类最常见的先天缺陷，但人们对导致面部错纹的发育基础知之甚少。几项研究已经确定了与形成下(腹面)面部图案有关的因素；然而，关于背面(上)面部的情况知之甚少。在人类中，锯齿状和Notch基因的突变与Alagille综合征有关，而异常的成纤维细胞生长因子信号导致Crouzon综合征。由于Alagille和Crouzon都观察到了类似的面部缺陷，Notch和FGF可能参与了面部骨骼图案的共同途径。在这个提议中，我研究了锯齿状缺口和成纤维细胞生长因子信号在斑马鱼促进背部面部认同感中的一个新的作用。在我的初步数据中，锯齿状Notch信号通过抑制骨骼前体中腹侧基因的表达来促进背部面部认同感；然而，Notch如何促进背部的分子机制尚不清楚。因此，在第一个目标中，我提出了一个模型，其中背侧面部身份是由起源于背侧区域的传播的Notch信令波来指定的。使用转基因Notch报告器和高分辨率成像，我将在构图阶段实时捕捉Notch的激活。在第二个目标中，我提出了建立在我最初发现的基础上的实验，即成纤维细胞生长因子信号也促进背部认同感。通过使用转基因FISH，在特定的发育时期，成纤维细胞生长因子信号被上调或抑制，我将确定成纤维细胞生长因子信号是否使用与Notch相似的分子机制来促进背部特性。在第三个目标中，我将测试锯齿状缺口和成纤维细胞生长因子信号通路是如何整合在一起，以积极促进背部面部认同感的。在这里，我提出了一个线性和并行的信号集成模型。在线性模型中，成纤维细胞生长因子信号通过控制jagib的表达来激活Notch通路。在平行模型中，成纤维细胞生长因子和Notch独立地激活与背侧面部模式有关的相同下游靶点。为了测试这一点，我将使用突变和转基因的组合，通过改变Notch和成纤维细胞生长因子信号来确定这两条途径是如何整合的。这项提议的目的是研究锯齿状缺口和成纤维细胞生长因子信号在脊椎动物上面部图案化中的新作用。由于锯齿状1和成纤维细胞生长因子受体2的突变与Alagille和Crouzon综合征的头面部缺陷有关，我在斑马鱼上的工作将揭示这些途径的中断导致人类面部缺陷的发育基础。

DESCRIPTION (provided by applicant): Craniofacial abnormalities are the most common human birth defects, and yet little is known about the developmental basis that leads to mispatterning of the face. Several studies have Identified factors involved in patterning the lower (ventral) face; however, less is known about the dorsal (upper) face. In humans, mutations in Jagged and Notch have been linked to Alagille syndrome, whereas aberrant Fgf signaling results in Crouzon syndrome. As similar facial defects are observed in both Alagille and Crouzon, Notch and Fgf may be involved in a common pathway that patterns the facial skeleton. In this proposal, I investigate a novel role of Jagged-Notch and Fgf signaling in zebrafish involved in promoting dorsal facial identity. In my preliminary data, Jagged-Notch signaling promotes dorsal facial identity by repressing ventral gene expression in skeletal precursors; however, the molecular mechanism of how Notch promotes dorsal remains unknown. Thus in the first aim, I propose a model where dorsal facial identity is specified by a propagating Notch signaling wave that originates in the dorsal domain. Using a transgenic Notch reporter and high-resolution imaging, I will capture Notch activation in real time during patterning stages. In the second aim, I propose experiments that build on my initial findings that Fgf signaling also promotes dorsal identity. By using transgenic fish, in which Fgf signaling is upregulated or inhibited at specific times of development, I will determine if Fgf signaling uses similar molecular mechanisms as Notch to promote dorsal identity. In the third aim, I will test how Jagged-Notch and Fgf signaling pathways are integrated to actively promote dorsal facial identity. Here, I propose a linear and a parallel model of signal integration. In the linear model, Fgf signaling activates the Notch pathway by controlling jagib expression. In the parallel model, Fgf and Notch independently activate the same downstream targets involved in dorsal facial patterning. To test this, I will use combinations of mutants and transgenics with altered Notch and Fgf signaling to determine how these two pathways are integrated. The goal of this proposal is to investigate a novel role of Jagged-Notch and Fgf signaling in patterning the vertebrate upper face. As mutations in Jagged 1 and the Fgf receptor 2 have been linked to craniofacial defects in Alagille and Crouzon syndrome, my work in zebrafish will reveal the developmental basis by which disruption of these pathways results in facial defects in humans.