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

描述（由申请人提供）：颅面畸形是最常见的人类出生缺陷，但对导致面部错误模式的发育基础知之甚少。几项研究已经确定了影响下（腹侧）脸形成的因素；然而，对背侧（上）脸的了解较少。在人类中，Jagged和Notch的突变与Alagille综合征有关，而Fgf信号异常导致Crouzon综合征。由于在Alagille和Crouzon中观察到相似的面部缺陷，Notch和Fgf可能参与了面部骨骼模式的共同途径。在本提案中，我研究了斑马鱼中锯齿状缺口和Fgf信号在促进背侧面部识别中的新作用。在我的初步数据中，锯齿状notch信号通过抑制骨骼前体的腹侧基因表达来促进背侧面部身份；然而，Notch如何促进背侧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域的传播Notch信号波指定的。使用转基因Notch报告和高分辨率成像，我将在模式阶段实时捕获Notch激活。在第二个目标中，我提出了基于Fgf信号也促进背侧身份的初步发现的实验。通过使用Fgf信号在特定发育时期上调或抑制的转基因鱼，我将确定Fgf信号是否使用与Notch相似的分子机制来促进背侧身份。在第三个目标中，我将测试Jagged-Notch和Fgf信号通路如何整合以积极促进背侧面部身份。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，Fgf信号通过控制jagib表达激活Notch通路。在平行模型中，Fgf和Notch独立激活涉及背侧面部模式的相同下游目标。为了验证这一点，我将使用突变体和带有改变Notch和Fgf信号的转基因组合来确定这两种途径是如何整合的。本提案的目的是研究锯齿状缺口和Fgf信号在脊椎动物上面部图案中的新作用。由于Jagged 1和Fgf受体2的突变与Alagille综合征和Crouzon综合征的颅面缺陷有关，我在斑马鱼身上的工作将揭示这些通路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.