Regulation of Mesodermal Progenitors in Transgenic Zebrafish

转基因斑马鱼中胚层祖细胞的调控

基本信息

批准号：
8890841
负责人：
David Kimelman
金额：
$ 31.6万
依托单位：
UNIVERSITY OF WASHINGTON
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-07-01 至 2016-06-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): A hallmark of early vertebrate development is the progressive growth of the embryonic body from the anterior (A) to the posterior (P), which relies on a multipotent stem-like progenitor population located at the most posterior end of the embryo, in a region called the tailbud. This progenitor population gradually releases mesodermal cells that populate the somites (primarily muscle), as well as neural cells that form the spinal cord, until the complete A-P axis has been established. For the body to form normally, both the rate of release from the tailbud and cell proliferation must be carefully controlled so tht the correct proportion of cells is produced along the entire A-P axis. How these processes are regulated and integrated is poorly understood. The first aim of this proposal will examine the mechanisms by which cells leave the tailbud and enter the somites. Based on recent preliminary results with a new transgenic line, the role of Wnt signaling in regulating this process will be elucidated by testing two hypotheses for Wnt function. In addition, analysis of a small unique element within the tbx16/spadetail promoter, which is activated just as cells make the decision to leave the progenitor population, will provide key insight into the molecular mechanism that regulates the initial step in the commitment to the mesodermal fate as the body elongates. Identifying the mechanisms that control cell allocation will be a major step forward in understanding how the vertebrate embryo precisely regulates the release of cells from the tailbud. The second aim will determine why cell proliferation is tightly regulated in the post-gastrula embryo such that the progenitors are quiescent, and only divide when they first begin to differentiate. This aim will test the hypotheses that this regulation is essential to allow normal signaling and/or morphogenesis of the mesodermal progenitors and their derivatives using a novel transgenic line we have recently produced. Determining why the vertebrate embryo strictly controls proliferation is essential for understanding how the embryo regulates the competing needs to increase cell number yet maintain the complex signaling and morphogenetic processes necessary to establish the embryonic body plan. Studies, particularly in mammals, show that the posterior progenitors are a stem-cell like population, which contribute to a variety of cell types. With the ability to produce transgenic lines expressing temporally controlled regulators of signaling and cell proliferation, as well as the ability to easily knock down gene function, zebrafish provides an excellent model system for understanding how vertebrate stem cells are regulated in vivo. As stem cells have great promise for the treatment of many diseases, the studies described here will provide valuable information about the signaling networks and regulatory factors that control stem cell maintenance and tissue formation.

描述（由申请人提供）：早期脊椎动物发育的一个标志是胚胎体从前部（A）到后部（P）的逐渐生长，这依赖于位于最后端的多能干状祖细胞群胚胎的一个区域，称为尾芽。该祖细胞群逐渐释放出体节（主要是肌肉）中的中胚层细胞以及形成脊髓的神经细胞，直到建立完整的 A-P 轴。为了使身体正常形成，必须仔细控制尾芽的释放速率和细胞增殖，以便沿着整个 A-P 轴产生正确的细胞比例。人们对这些过程如何监管和整合知之甚少。该提案的第一个目标是研究细胞离开尾芽并进入体节的机制。根据最近对新转基因系的初步结果，将通过测试 Wnt 功能的两个假设来阐明 Wnt 信号传导在调节这一过程中的作用。此外，对 tbx16/spadetail 启动子内的一个小的独特元件（当细胞决定离开祖细胞群时被激活）的分析将为调节中胚层承诺的初始步骤的分子机制提供关键的见解。命运随着身体的拉长而变化。确定控制细胞分配的机制将是理解脊椎动物胚胎如何精确调节尾芽释放细胞的重要一步。第二个目标将确定为什么细胞增殖在原肠胚后胚胎中受到严格调节，使得祖细胞处于静止状态，并且仅在它们第一次开始分化时才分裂。这一目标将测试以下假设：这种调节对于使用我们最近生产的新型转基因系实现中胚层祖细胞及其衍生物的正常信号传导和/或形态发生至关重要。确定脊椎动物胚胎严格控制增殖的原因对于理解胚胎如何调节增加细胞数量的竞争性需求，同时维持建立胚胎身体计划所需的复杂信号传导和形态发生过程至关重要。研究，特别是在哺乳动物中的研究表明，后祖细胞是一个类似干细胞的群体，有助于形成多种细胞类型。斑马鱼能够产生表达信号和细胞增殖的时间控制调节因子的转基因系，并且能够轻松敲除基因功能，为了解脊椎动物干细胞在体内的调节方式提供了一个极好的模型系统。由于干细胞在治疗许多疾病方面有着巨大的前景，这里描述的研究将提供有关控制干细胞维持和组织形成的信号网络和调节因子的有价值的信息。