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Molecular mechanism of morphogenetic movements in amphibian embryos

两栖动物胚胎形态发生运动的分子机制

基本信息

批准号：
12680713
负责人：
KUBOTA Hiroshi
金额：
$ 2.37万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680713/
关键词：
morphogenetic movement Xenopus gastrulation champignon STI1 Hop Xoom Xenopus gastrulation molecular mechanism

项目摘要

Gastrulation is the most dynamic morphogenetic movement and initiates the body plan in animal development. In order to analyze the molecular mechanism of gastrulation, we have isolated a novel kuppel-like transcription factor, champignon (cpg), that encodes POZ/Zinc finger protein by expression screening in Xenopus laevis. Overexpression of cpg resulted in interference with gastrulation. Comparison of the constituent proteins from control embryos and cpg-injected embryos at stage 11.5 revealed that a 61 kDa protein spot was shifted basically in cpg-injected embryos suggesting that the 61 kDa protein was dephosphorylated by cpg-injection. Partial amino acid sequence (23 mer) of the 61 kDa protein accords 100 % with that of putative Xenopus STI1 protein which is a homolog of stress-induced phosphoprptein (STI1), Hsp70/Hsp90-organizing protein (Hop), or transformation-sensitive protein. The STI1/Hop combines Hsp70 with Hsp90 and modulates the function of Hsp90 chaperone which is known to bind to cytoskeletons. Thus the inhibitory role of cpg on gastrulation is mediated by dephosphorylation of XSTI1. These results suggest that the Hsp90 chaperone is involved in the control of morphogenetic movements.We have also cloned a novel gene, Xoom, which encodes a transmembrane protein. Injection of Xoom antisense RNA into Xenopus embryos reduced the Xoom protein and caused gastrulation defects without any influence on the involution and expression of mesodermal marker genes. Comparison of cell shape among various experimental conditions showed that inhibition of cell spreading occurs specifically in the outer ectodermal layer of the antisense RNA-injected embryo. Cytological examination indicated disorgatrization of F-actin in the ectodermal cells of the antisense RNA-injected embryo. These results suggest that Xoom plays an important role in the epibolic movement of ectodermal cells through some regulation of actin filament organizaiion.

在动物的发育过程中，原肠胚形成是最具活力的形态发生运动，是机体计划的起始。为了分析原肠胚形成的分子机制，我们通过表达筛选，在非洲爪蟾中分离到一个编码POZ/锌指蛋白的新型kuppel样转录因子--campignon（cpg）。cpg的过表达导致原肠胚形成的干扰。在11.5期比较对照胚胎和注射cpg的胚胎的组成蛋白，发现在注射cpg的胚胎中61 kDa的蛋白质点基本上发生了位移，这表明61 kDa的蛋白质被cpg注射去磷酸化。61 kDa蛋白的部分氨基酸序列（23 mer）与推测的非洲爪蟾STI 1蛋白的氨基酸序列100%一致，该蛋白是应激诱导磷酸蛋白（STI 1）、Hsp 70/Hsp 90组织蛋白（Hop）或转化敏感蛋白的同源物。STI 1/Hop将Hsp 70与Hsp 90结合，并调节已知与细胞骨架结合的Hsp 90伴侣蛋白的功能。因此，cpg对原肠胚形成的抑制作用是通过XSTI 1的去磷酸化介导的。我们还克隆了一个新的基因Xoom，它编码一个跨膜蛋白。将Xoom反义RNA注射到非洲爪蟾胚胎中，减少了Xoom蛋白，并导致原肠胚形成缺陷，而对中胚层标记基因的退化和表达没有任何影响。不同实验条件下细胞形态的比较表明，细胞扩散的抑制特异性地发生在注射反义RNA的胚胎的外外胚层。细胞学检查表明，在注射反义RNA的胚胎的外胚层细胞的F-肌动蛋白的disorgatrization。这些结果表明，Xoom通过调节肌动蛋白丝的组织，在外胚层细胞的外胚层运动中起着重要作用。