Molecular Analysis of the Segmentation Clock

描述（由申请人提供）：我们对脊椎动物轴的形态发生感兴趣，特别是对身体超构结构的模式和分化感兴趣。在脊椎动物胚胎中，最明显的异聚结构是体体，它产生了身体的分节结构，包括轴骨、背部真皮和所有骨骼肌。与此应用相关的研究的中心主题是了解在分子水平上调节脊椎动物胚胎身体计划分割的级联事件。我们将重点研究一种叫做“分割时钟”的分子振荡器，它是我们几年前发现的。这种分子时钟的节律与片段相似，最初是在鸡胚胎中发现的，作为编码体前中胚层（PSM）特定基因的mRNA脉冲。分割时钟现已在鱼、鸡和小鼠中被发现，并控制“循环基因”的周期性表达，到目前为止，这些基因都与Notch通路有关。目前还不清楚分割时钟的机制及其在分割过程中的确切作用。关于分割时钟的分子机制，一个主要的问题是Notch信号的作用。我们对小鼠和鱼类的初步研究和遗传证据表明，该途径在振荡的控制中起重要作用，但是否在振荡的核心机制中起作用尚不清楚。该项目的一个主要目的是在分子和细胞水平上进行实验，以表征Notch通路在振荡器功能中的作用。我们还发现FGF信号控制着鸡胚分割程序的激活和体细胞边界的定位。我们打算在这个过程中确定FGF通路的各个组成部分的含义，我们将检查FGF信号与分割时钟的相互作用。最后，我们提供了分割时钟与轴形成过程中Hox基因激活或维持之间耦合的证据，我们打算进一步表征鸡胚胎发生过程中的这种相互作用。对分割时钟功能的理解具有相当大的临床意义，因为在人类中，与该振荡器功能相关的基因突变，如delta-样3 (dll3)，会导致脊柱异常分割，类似于在脊柱脊柱失稳综合征中所见的情况。

DESCRIPTION (provided by applicant): We are interested in the morphogenesis of the vertebrate axis and more particularly in the patterning and differentiation of the metameric structures of the body. In the vertebrate embryo, the most overt metameric structures are the somites, which give rise to the segmented structures of the body including the axial skeleton, the dermis of the back and all skeletal muscles. The central theme of the research relevant to this application is to understand the cascade of events, which regulate the segmentation of the body plan of vertebrate embryos at the molecular level. We will essentially focus on the study of a molecular oscillator called the " Segmentation Clock" which we identified a few years ago. This molecular clock whose rhythm parallels that of segmentation was originally discovered in the chick embryo as pulses of mRNA coding for specific genes in the presomitic mesoderm (PSM). The Segmentation Clock has now been identified in fish, chick and mouse and controls the periodic expression of "Cyclic Genes " which are, so far, all related to the Notch pathway. Neither the mechanism underlying the Segmentation Clock nor its precise role in the segmentation process are currently understood. A major question to be asked regarding the molecular machinery of the Segmentation Clock concerns the role of Notch signaling. Our preliminary studies and genetic evidence in mouse and fish suggest that this pathway plays an important role in the control of the oscillations but it is not known whether it acts in the core mechanism of the oscillator. A major aim of this project will be to carry out experiments at the molecular and cellular level to characterize the role of the Notch pathway in the function of the oscillator. We also showed that FGF signaling controls the activation of the segmentation program and the positioning of somitic boundaries in the chick embryo. We intend to establish the implication of the various components of the FGF pathway in this process, and we will examine the interaction of FGF signaling with the Segmentation Clock. Finally, we have provided evidence for a coupling between the Segmentation Clock and the activation or maintenance of Hox genes during axis formation, and we intend to further characterize this interaction during chick embryogenesis. The understanding of the functioning of the Segmentation Clock is of considerable clinical relevance, since in humans mutations in the genes associated with the function of this oscillator such as delta-like 3 (dll3) result in abnormal segmentation of the vertebral column similar to that seen in the spondylocostal dysostosis syndrome.