MOLECULAR MECHANISM OF SORTING OUT OF CELLULAR SLIME MOLDS

本项目取得的主要成果已在此介绍。在细胞黏菌Polysphondylium的发育后期，发生了二次茎的形成。它有可能成为次生茎形成的抑制因子。即gp64通过融合蛋白引导ecmB启动子的方式，在盘基骨柱细胞中连续表达。茎的次生形成完全停止，表明gp64抑制了茎的早熟次生形成。IagC是盘基骨柱紧密丘形成及其进一步发育的几个关键基因之一，最近从日本cDNA项目ESTs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。进一步将lagC和lagCII基因同源重组，获得了一个双敲除突变体，其表型也未发生变化。因此，我们正在进行lagci3过表达基因的分析。为了分离一种新的细胞-细胞粘附蛋白，我们制备了双敲除lagC和gp80o基因的突变体。突变体pehnotype在发育后期显示edta抗性细胞-细胞粘附的延迟表达，表明在发育后期存在另一种细胞粘附分子。

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.