Regulatory mechanisms controlling pattern formation in the vertebrate embryo

我正在进行的研究计划旨在发现脊椎动物的身体计划是如何建立的。分节的身体平面图是许多后生动物的共同特征。在脊椎动物中，脊柱、脊神经和躯干的肌肉组织中的分段是明显的。这种模式的蓝图是由称为体节的同色异谱结构建立的。这些组织由不分节的近轴中胚层形成，近轴中胚层组织成上皮球，上皮球沿神经管两侧沿着分布。体节的形成在严格调控的时间和空间顺序与体节添加每30分钟在斑马鱼，和每2小时在小鼠中，随着胚胎向后延伸。形态梯度建立早期体轴信息。这些分子启动信号转导级联，汇聚在转录调节蛋白上，然后将此信息解释为基因表达的变化。我未来5年的目标集中在基因调控事件如何控制近轴中胚层特化形成体节。先前的功能研究表明，属于Forkhead box C家族（FOXC）的转录因子是体节形成的重要调控因子。Foxc基因在斑马鱼和小鼠发育过程中的近轴中胚层（PM）和所有体节中表达。斑马鱼foxc 1a功能的缺失破坏了胚胎前部前8-10个体节的形成，但后部体节的形成似乎不受影响。小鼠Foxc 1和Foxc 2功能的缺失导致胚胎在交配后9.5天死亡，并导致分节体节的缺失。这些小鼠在发育中仅在前部体节形成的阶段停滞，因此不知道这些Foxc基因是否是胚胎后部体节形成所需的。我的假设是，Foxc基因（小鼠的Foxc 1和Foxc 2;斑马鱼的foxc 1a）的功能优先于前体节的规范和形成，尽管它们存在于后体节。我建议，目前在后PM和体节的因素，Foxc功能或补偿其损失的Foxc功能。我的短期研究目标将解决以下两个基本问题，以发现Foxc基因如何调节小鼠和斑马鱼体节形成的机制。1.在前体节和后体节的特化和形成过程中，Foxc TF的不同要求是什么？ 2.在形成前体节和后体节的PM中存在基因表达的差异吗？我的研究计划将使用斑马鱼和小鼠的功能丧失实验来发现Foxc基因参与形成体节的转录调控机制。这项工作也将提供关键的发现，形成前与后体节，以及揭示机制的差异，可能发生在体节发生在水生与陆生脊椎动物。

My ongoing research program aims to discover how the vertebrate body plan is established. A segmented body plan is a common feature of many metazoan organisms. In vertebrates, segmentation is evident in the vertebral column, spinal nerves and musculature of the trunk. The blueprint for this pattern is established by metameric structures called somites. These tissues form from unsegmented paraxial mesoderm that organizes into epithelial spheres lying bilaterally along the neural tube. Somites form in a tightly regulated temporal and spatial sequence with somites added every 30 minutes in zebrafish, and every 2 hours in mice, as the embryo extends posteriorly. Morphogen gradient establish early body axis information. These molecules initiate signal transduction cascades that converge on transcriptional regulatory proteins which then interpret this information into changes in gene expression. My goal for the next 5 years focuses on how gene regulatory events controls paraxial mesoderm specification to form somites. Previous functional studies show that transcription factors belong to the Forkhead box C family (FOXC) are essential regulators for somite formation. Foxc genes are expressed in paraxial mesoderm (PM) and throughout all somites during zebrafish and mouse development. Loss of foxc1a function in zebrafish disrupts the formation of first 8-10 somites in the anterior of the embryo but somites forming in the posterior appear unaffected. Loss of both Foxc1 and Foxc2 function in mice causes embryonic lethality at 9.5 days post coitum and results in the absence of segmented somites. These mice arrest in development at a stage where only the anterior somites form, thus it is not known whether these Foxc genes are required for somite formation in the posterior of the embryo. My hypothesis is that Foxc genes (Foxc1 and Foxc2 in mice; foxc1a in zebrafish) function preferentially for the specification and formation of anterior somites despite their presence in the posterior somites. I propose that factors present in the posterior PM and somites, inactivate Foxc function or compensate for its loss of Foxc function. My short-term research goals will address the following two fundamental questions to discover the mechanisms of how Foxc genes regulate the formation of somites in mice and zebrafish. 1. What are the different requirements for Foxc TFs during specification and formation of anterior versus posterior somites? 2. Do differences in gene expression exist in the PM that forms anterior somites vs posterior somites? My research program will use loss of function experiments in zebrafish and mice to discover the transcriptional regulatory mechanisms that Foxc genes participate in to form somites. This work will also provide key discoveries into formation of anterior vs posterior somites as well as uncover mechanistic differences that may occur in somitogenesis in aquatic vs terrestrial vertebrates.