Twisted Gastrulation Gene in Vertebrate Development

描述（由申请人提供）：拟议的研究旨在了解可溶性蛋白扭曲原肠胚形成（Tsg）调节早期脊椎动物胚胎发生的分子机制。重点将放在Tsg用于修改骨形态发生蛋白（BMPs）信号的策略上。bmp是一种多用途的生长因子，控制着脊椎动物早期发育的多个过程，如背腹模式、各种器官的形态发生和器官发生。BMP的活性受多种分泌因子的调控，包括BMP拮抗剂chordin和chordin灭活酶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节BMP信号。Tsg可阻断斑马鱼和爪蟾的BMP功能；然而，它也会在青蛙中引起一些缺陷，部分模仿BMP过度表达的表型。Tsg在体内的作用机制尚不清楚。在该实验室进行的初步研究表明，Tsg在背部和腹侧区域都是正常青蛙胚胎发生所必需的；Tsg可能与脊索蛋白协同控制背前发育。Tsg在体内可在细胞外周检测到，Tsg过表达可影响细胞运动。本研究将验证Tsg与脊索蛋白和BMP复合物可能参与BMP配体的运输，从而调节BMP信号的假设；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，将通过功能丧失方法在分子水平上进一步研究Tsg， chordin， tolloid相关蛋白酶和bmp的体内相互作用。在目标2中，将分析在存在或不存在Tsg和/或chordin的情况下，早期青蛙胚胎外胚层中bmp的分布。在目标3中，将研究Tsg对细胞运动的影响。在目标4中，将研究Tsg与不同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功能的机制提供重要线索，并将有助于我们理解细胞外蛋白网络对BMP信号的调节。

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.