MOLECULAR MECHANISM OF SORTING OUT OF CELLULAR SLIME MOLDS

本文介绍了该项目取得的主要成果。在细胞黏菌Polysphondylium发育后期，出现次生茎的形成。Gp64可能作为次生柄形成的抑制因子，通过融合蛋白引导ecmB启动子的方式在Dictyostelius细胞中持续表达。茎的二次形成完全停止，说明gp64抑制了茎的早熟二次形成。IagC是参与网柄网柄菌紧密丘形成及其进一步发育的少数几个关键基因之一，最近从日本cDNA计划的EST中分离到一个相关序列，命名为lagCII。为了了解这个lagCII的功能作用，我们敲除了这个基因，但没有表型变化。在此基础上，我们又获得了一个lagC和lagCII基因同源重组的双基因敲除突变体，同样没有表型变化。因此，我们正在进行LagCII基因过表达的分析。为了分离出一种新的细胞-细胞黏附蛋白，在网柄苔藓的发育后期，我们进行了lagC和gp8O基因的突变。突变型细胞在发育后期延迟表达抗乙二胺四乙酸二钠的细胞-细胞黏附，表明在发育后期还存在另一种细胞黏附分子S。

The major results obtained during this project have been described here.1. At the late development of the cellular slime mold Polysphondylium, there occurs the secondary stalk formation. The possibility to be as a suppressor of the secondary stalk formation was undertaken.Namely gp64 was forced to express in Dictyostelium cells continuously by the way of the fusion protein directing an ecmB promotor. The secondary formation of stalk was completely stopped, indicating that gp64 inhibits the precocious secondary formation of the stalks.2. IagC is one of a few critical genes involved in the tight mound formation and its further development of Dictyostelium, and recently a related sequence isolated from ESTs of the Japan cDNA project, designated as lagCII, had been found. To see the functional role of this lagCII, we knocked out this gene, but with no phenotypic change. Further we made a double knock out mutant which both lagC and lagCII genes were recombined by homologously, it was again no change of phenotype. Therefore we are undertaking the analysis of overexpressor of lagCII.3. To isolate a new cell-cell adhesion protein in the late development of Dictyostelium, we made mutants which lagC and gp8O genes weredoubly knocked out. The mutant pehnotype showed a delayed expression of a EDTA-resistant cell-cell adhesion during late development, indicating that there are another cell adhesion molecule(s) in the late development.