MOLECULAR MECHANISM OF SORTING OUT OF CELLULAR SLIME MOLDS

本文介绍了本项目所取得的主要成果.在细胞型黏菌多毛类的发育后期，会发生次生柄的形成。探讨了gp 64作为次生柄形成抑制因子的可能性，即通过融合蛋白引导ecmB启动子，使gp 64在网骨藻细胞中持续表达。茎的次生形成完全停止，表明gp 64抑制了茎的早熟次生形成. IagC是与网骨藻紧密丘形成和进一步发育有关的几个关键基因之一，最近从日本cDNA计划的EST中分离到一个相关序列，命名为lagCII，为了了解该lagCII的功能，我们敲除了该基因，但没有表型改变。进一步构建了lagC和lagCII基因同源重组的双敲除突变体，其表型也没有改变。因此，我们正在进行lagCII的过表达分析。为了分离一种新的细胞间粘附蛋白，我们构建了lagC和gp 8 O基因双重敲除的突变体。突变型在发育后期表现出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.