Studies on the role of growth factors in embryonic inductions

生长因子在胚胎诱导中作用的研究

基本信息

批准号：
03833001
负责人：
UENO Naoto
金额：
$ 1.15万
依托单位：
University of Tsukuba, Institute of Applied Biochemistry
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Growth factors have been implicated in the regulation of early development. Although activin,a member of TGF-beta related growth factor family was discovered as a stimulator of FSH secretion from pituitary cells,it has recently been shown to induce mesodermal tissues from presumptive ectoderm of Xenopus laevis. In order to understand more precisely the molecular mechanism of the mesoderm induction,we have screened a genomic DNA library of Xenopus laevis with rat activin betaALPHA gene as a probe. We have isolated 5 independent genes and one of the genes was found to be encoding a protein closely related to mammalian activin. Interestingly,the rest of the gene contained an amphibian counterpart of mammalian bone morphogenetic proteins, which was purifed based on their ability to induce ectopic bone formation in vivo. Eventually,we isolated cDNAs of Xenopus activin,BMP-2,-4 and -7.Functional analysis has been performed for the growth factor cDNAs by injecting their RNA into early blastomeres early Xenopus embryos to see the effect of overexpression of their gene product. Overexpression of activin in ventral half resulted in duplication of body axis,suggesting that activin play a role in dorsalization. On the other hand,over expression of BMP-4 in dorsal half inhibited the formation of anterior and dorsal structure,suggesting that BMP may be important for ventralization. These results suggest that activin and BMP have distinct role in pattern formation of early embryos.

生长因子与早期发育的调节有关。尽管激活素（TGF-β相关生长因子家族的成员）被发现是垂体细胞分泌FSH的刺激剂，但最近显示它可以诱导非洲爪蟾假定外胚层的中胚层组织。为了更准确地了解中胚层诱导的分子机制，我们以大鼠激活素βALPHA基因为探针，筛选了非洲爪蟾基因组DNA文库。我们分离出5个独立的基因，其中一个基因被发现编码与哺乳动物激活素密切相关的蛋白质。有趣的是，该基因的其余部分包含哺乳动物骨形态发生蛋白的两栖动物对应物，该蛋白是根据其在体内诱导异位骨形成的能力而被纯化的。最终，我们分离出了爪蟾激活素、BMP-2、-4和-7的cDNA。通过将其RNA注射到爪蟾早期胚胎的早期卵裂球中，对生长因子cDNA进行了功能分析，以观察其基因产物过表达的效果。激活素在腹侧的过度表达导致体轴重复，表明激活素在背侧化中发挥作用。另一方面，BMP-4在背半部的过度表达抑制了前部和背部结构的形成，表明BMP可能对腹侧化很重要。这些结果表明激活素和 BMP 在早期胚胎的模式形成中具有不同的作用。