Regulatory mechanisms controlling pattern formation in the vertebrate embryo

我正在进行的研究项目旨在发现脊椎动物的身体结构是如何建立的。分段的身体结构是许多后生动物的共同特征。在脊椎动物中，脊柱、脊神经和躯干肌肉组织的分割是明显的。这种模式的蓝图是由称为体母的超聚结构建立的。这些组织由未分节的近轴中胚层形成，沿神经管两侧组织成上皮球。随着胚胎向后延伸，斑马鱼每30分钟添加一次体，小鼠每2小时添加一次体，体在严格调控的时间和空间序列中形成。形态形成梯度建立早期体轴信息。这些分子启动信号转导级联，聚集在转录调节蛋白上，然后将这些信息解释为基因表达的变化。我未来5年的目标是研究基因调控事件如何控制近轴中胚层规范形成体。以往的功能研究表明，叉头盒C家族（FOXC）的转录因子是somite形成的重要调控因子。Foxc基因在斑马鱼和小鼠发育的近轴中胚层（PM）和所有体中表达。在斑马鱼中，foxc1a功能的丧失会破坏胚胎前部前8-10个体的形成，但在后部形成的体似乎不受影响。小鼠中Foxc1和Foxc2功能的缺失会导致交配后9.5天的胚胎死亡，并导致节段体缺失。这些小鼠的发育停滞在仅形成前体的阶段，因此不知道这些Foxc基因是否需要胚胎后部体的形成。我的假设是Foxc基因（小鼠中的Foxc1和Foxc2；斑马鱼中的foxc1a）尽管存在于后体细胞中，但它们在前体细胞的规范和形成中优先发挥作用。我认为存在于PM后部和某些部位的因素使Foxc功能失活或补偿其Foxc功能的丧失。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内体形成的机制。1. 在前体和后体的形成过程中对Foxc TFs有什么不同的要求？2. 在形成前体体和后体体的PM中存在基因表达差异吗？我的研究项目将使用斑马鱼和小鼠的功能丧失实验来发现Foxc基因参与形成体的转录调控机制。这项工作还将为前体和后体的形成提供关键发现，并揭示水生和陆生脊椎动物中可能发生的体发育机制差异。

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.