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Comparative studies on early neural-type differentiation between isolated blastomeres of protochordate embryos and teratocarcinoma cell lines derived from mouse primitive ectoderm.

原索动物胚胎分离卵裂球与小鼠原始外胚层畸胎癌细胞系早期神经型分化的比较研究。

基本信息

批准号：
62440023
负责人：
TAKAHASHI Kunitaro
金额：
$ 19.2万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

As previously reported, when the Halocynthia embryo, a protochordate, is cleavage-arrested at early developmental stages, 1- to 4-cell, and cultured further until the normal hatching time, the membrane of the large blastomeres expresses exclusively the epidermal-type excitability, while when cleavage-arrested after 8-cell stage, some of blastomeres show neural-type excitability. The difference can be caused by further segregation of egg cytoplasmic factors and/or cell-cell interaction after 8-cell stage. In the present project, a single anterior-animal blastomere which includes the presumptive neural region in the 8-cell embryo, when dissociated, cleavage-arrested and cultured in solution, differentiated exclusively to epidermal type judging from membrane excitability and immunoreactivity. However, when the same blastomere was cultured in contact with a single anterior-vegetal blastomere which includes the presumptive notochordal region, it displayed Na spikes, characterized by Na and … More K channels, and showed no expression of the epidermal antigen, suggesting "neural induction" resulted in a single cell during the interaction with a single neighboring cell. The contact necessary for this inductive interaction between an anterior-animal blastomere and an anterior-vegetal blastomere had a critical period before and after which the contact became ineffective and the period was between 64-cell stage and mid-gastrula stage of the control embryo. Further, some agents which mimic the inductive effects upon the anterior-animal blastomere were looked for and a proteolytic enzyme was found to develop Na spikes exactly identical with those induced by the cell-cell contact. Finally studying the mammalian embryonic system in comparison with the protochordate inductive system, the stem cells of cloned teratocarcinoma cell line derived from the primitive ectoderm of the 5 day mouse embryo was chemically induced to differentiate into neurons. The early stage of neural differentiation was characterized by expression of Na channels, T-type Ca channels, and 160 kD neurofilament protein in a round cell without neurite extension. Less

据报道，当原脊索类胚胎在发育早期(1-4-细胞)被卵裂阻止，并进一步培养到正常孵化时间时，大卵裂球的膜只表达表皮型兴奋性，而当8-细胞期后卵裂停止时，一些卵裂球表现出神经型兴奋性。这种差异可能是由于卵细胞胞质因子的进一步分离和/或8-细胞期后的细胞-细胞相互作用造成的。在本项目中，包括8-细胞胚胎中假定的神经区的单个前动物卵裂球，当分离、卵裂停止并在溶液中培养时，根据膜的兴奋性和免疫反应性，完全分化为表皮类型。然而，当同样的卵裂球与包括假定脊索区域的单个前植物卵裂球接触时，它显示出Na峰，以Na和…为特征。更多的K通道，不表达表皮抗原，提示“神经诱导”导致了单个细胞与单个相邻细胞的相互作用。前动物卵裂球和前植物卵裂球之间的这种诱导相互作用所需的接触有一个关键期，在此之前和之后接触无效，这一时期介于对照胚胎的细胞期和原肠胚中期之间。此外，还寻找了一些模拟对前动物卵裂球的诱导作用的试剂，并发现一种蛋白水解酶产生与细胞-细胞接触所诱导的钠峰完全相同的钠峰。最后对哺乳动物胚胎系统进行了研究，并与原索诱导系统进行了比较，克隆的畸胎癌细胞系来源于5日龄小鼠胚胎原始外胚层的干细胞被化学诱导分化为神经元。神经分化早期的特点是Na通道、T型钙通道和160kD神经丝蛋白在圆形细胞中表达，而不是轴突延伸。较少