Twisted Gastrulation Gene in Vertebrate Development

描述(申请人提供)：建议的研究是为了了解一种可溶性蛋白质扭曲原肠形成(TSG)调节脊椎动物早期胚胎发生的分子机制。主要的焦点将是TSG用来修改来自骨形态发生蛋白(BMP)的信号的策略。BMP是一种多功能的生长因子，在脊椎动物早期发育过程中控制多个过程，如背腹模式形成、各种器官的形态发生和器官发生。BMPs的活性受多种分泌因子的调节，包括BMP拮抗剂Chordin和Chordin失活酶Tolloid/Xolloid/BMP1。最近，一种新的可溶性成分TSG被发现，它似乎以一种独特的方式调制BMP信号。TSG可以阻断斑马鱼和非洲爪哇的BMP功能；然而，它也在青蛙中诱导了一些部分模仿BMP过度表达的表型的缺陷。TSG在体内的作用机制尚不清楚。在本实验室进行的初步研究表明，TSG在青蛙的背部和腹侧区域都是正常胚胎发生所必需的；TSG可能与背部的Chordin合作来控制背部-前部的发育。TSG在体内存在于细胞外周，TSG的过表达可能影响细胞的运动。这项研究将验证以下假设：TSG可能参与BMP配体的运输，从而调节BMP信号；TSG可能通过影响细胞迁移行为来调节脊椎动物的发育。在目标1中，将通过功能丧失的方法在分子水平上进一步研究TSG、Chordin、Tolloid相关酶和BMPs之间的体内相互作用。在目标2中，将分析在有或没有TSG和/或Chordin存在的情况下，BMPs在早期青蛙胚胎外胚层中的分布。在目标3中，将检测TSG对细胞运动的影响。在目标4中，将研究TSG与不同的BMP和其他未知因素的直接相互作用。这些实验结果将为了解TSG的功能机制提供重要线索，并将有助于我们理解细胞外蛋白网络对BMP信号的调控。

DESCRIPTION (provided by applicant): The proposed research is to understand the molecular mechanisms through which a soluble protein, twisted gastrulation (Tsg), regulates the early vertebrate embryogenesis. A main focus will be on the strategies that Tsg uses to modify the signals from the bone morphogenetic proteins (BMPs). BMPs are versatile growth factors that control multiple processes during early vertebrate development, such as the dorsal-ventral patterning and the morphogenesis and the organogenesis of various organs. The activities of BMPs are regulated by many secreted factors, including the BMP antagonist chordin and the chordin inactivating enzymes tolloid/Xolloid/BMP1. Recently, a new soluble component, Tsg, has been identified, which seems to modulate the BMP signals in a unique way. Tsg can block the BMP function in both zebrafish and Xenopus; it, however, also induces some defects in frogs that partially mimic the phenotypes of the BMP overexpression. The mechanisms for the actions of Tsg in vivo are not well understood. Preliminary studies performed in this laboratory demonstrate that Tsg is required both in the dorsal and in the ventral regions for normal frog embryogenesis; Tsg may cooperate with chordin dorsally to control the dorsoanterior development. Tsg is detected at the cell periphery in vivo, and overexpression of Tsg may affect the cell movement. The proposed research will test the hypotheses that Tsg, in complex with chordin and BMPs, may be involved in the transportation of the BMP ligands and thus modulate the BMP signals; and Tsg may regulate the vertebrate development through its influence on the cell migratory behaviors. In aim 1, the in vivo interaction of Tsg, chordin, tolloid-related proteases and BMPs will be further studied at the molecular level by the loss-of-function approach. In aim 2, the distribution of the BMPs in the ectoderm of early frog embryos in the presence or the absence of Tsg and/or chordin will be analyzed. In aim 3, the influence of Tsg on cell movement will be examined. In aim 4, the direct interactions of Tsg with different BMPs and other unidentified factors will be studied. The results from these experiments will provide important clues on the mechanisms of the Tsg function, and will contribute greatly to our understanding on regulation of the BMP signals by a network of the extracellular proteins.