Regulatory mechanisms controlling pattern formation in the vertebrate embryo

控制脊椎动物胚胎模式形成的调节机制

• 批准号: RGPIN-2019-05085
• 负责人: Berry, Fred
• 金额: $ 2.33万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=715339
• 关键词: Regulatory; mechanisms; controlling; pattern; formation

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.

我正在进行的研究项目旨在发现脊椎动物的身体计划是如何建立的。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节的同色异谱结构建立的。这些组织由不分节的轴旁中胚层形成，组织成沿神经管两侧的上皮球。体节以严格调控的时间和空间顺序形成，随着胚胎向后延伸，斑马鱼每 30 分钟添加一次体节，小鼠每 2 小时添加一次体节。形态发生梯度建立早期身体轴信息。这些分子启动信号转导级联，汇聚到转录调节蛋白上，然后将这些信息解释为基因表达的变化。我未来 5 年的目标集中于基因调控事件如何控制近轴中胚层规范以形成体节。 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节因子。 Foxc 基因在斑马鱼和小鼠发育过程中的轴旁中胚层 (PM) 和所有体节中表达。斑马鱼中foxc1a功能的丧失会扰乱胚胎前部前8-10个体节的形成，但后部形成的体节似乎不受影响。小鼠中 Foxc1 和 Foxc2 功能同时丧失会导致交配后 9.5 天的胚胎死亡，并导致分段体节的缺失。这些小鼠在仅形成前体节的阶段停止发育，因此尚不清楚这些 Foxc 基因是否是胚胎后体节形成所必需的。我的假设是 Foxc 基因（小鼠中的 Foxc1 和 Foxc2；斑马鱼中的 Foxc1a）优先发挥前体节的规范和形成的作用，尽管它们存在于后体节中。我认为后 PM 和体节中存在的因素会使 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节形成的机制。 1. 在前体节和后体节的规范和形成过程中，Foxc TF 有哪些不同的要求？ 2. 形成前体节和后体节的 PM 中是否存在基因表达差异？ 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。这项工作还将为前体节和后体节的形成提供关键发现，并揭示水生和陆生脊椎动物体节发生中可能发生的机制差异。