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身体计划是如何建立的。分段的身体计划是许多后生生物的共同特征。在脊椎动物中，脊椎、脊神经和躯干的肌肉系统都有明显的节段。这种模式的蓝图是由被称为体节的变色异体结构建立的。这些组织由未分割的旁轴中胚层形成，这些中胚层组织成沿神经管两侧的上皮球。随着胚胎向后延伸，斑马鱼每30分钟增加一次体节，老鼠每2小时增加一次体节，形成严格控制的时间和空间序列。形态梯度建立早期的体轴信息。这些分子启动信号转导级联，汇聚到转录调控蛋白上，然后转录调控蛋白将这些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规格来形成体节。 以往的功能研究表明，属于Forkhead box C家族(FOXC)的转录因子是体节形成的重要调节因子。在斑马鱼和小鼠的发育过程中，FOXC基因在旁中胚层(PM)和所有体节都有表达。斑马鱼丧失foxc1a功能会扰乱胚胎前部8-10个体节的形成，但在后部形成的体节似乎不受影响。在小鼠中，Foxc1和FOXC2功能的丧失会导致在性交后9.5天的胚胎死亡，并导致缺乏节段性体节。这些小鼠在只有前体节形成的阶段停止发育，因此尚不清楚这些foxc基因是否是胚胎后部体节形成所必需的。我的假设是，foxc基因(在小鼠中为foxc1和foxc2；在斑马鱼中为foxc1a)优先用于指定和形成前体节，尽管它们存在于后体节中。我认为，存在于后部PM和体节的因素，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基因如何调节老鼠和斑马鱼体节的形成机制。 1.在前体节和后体节的特化和形成过程中，对Foxc Tf有什么不同的要求？ 2.前体节和后体节的PM在基因表达上是否存在差异？ 我的研究计划将利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。这项工作还将提供关于水生和陆生脊椎动物体节形成的关键发现，以及揭示水生和陆生脊椎动物在体细胞发生过程中可能出现的机制差异。

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.