Development of methods for using fission yeast as a test tube for analyzing highly complex biological systems.

在本研究期间，我们重点研究了调控裂殖酵母分化起始的新元件，分离出了4个调控分裂酵母分化起始和切换生长分化的关键元件。一个是phhl^+，编码一种与哺乳动物p38高度同源的应激图蛋白激酶。分析表明，phh1是营养饥饿所必需的，它诱导了Ste11的诱导，Ste11是启动分化的关键转录因子，为胁迫促进分化提供了分子基础。第二个是rcdl^+，它的结构同源物至少存在于萌芽中的酵母、植物、线虫和人类中。Rcdl^+是氮饥饿诱导分化和Ste11诱导所必需的。人类rcdl^+的同源物在卵巢、脾和胸腺等细胞增殖和分化活跃的器官中大量表达。第三个是编码典型的核糖核酸结合…的nrdl^+更多的蛋白质。分析表明，该基因的生物学作用是通过抑制Ste11调控的基因来抑制分化，这些基因对接合和/或减数分裂至关重要，直到细胞达到饥饿的临界点。我们还以裂解酵母为宿主，通过表达克隆的方法分离了大鼠和人的nrdl^+同源基因。它们被命名为ROD1。在裂解酵母中，ROD1和nrdl^+在功能上没有区别。ROD1在人类造血细胞系中的过表达有效地阻止了其向巨核细胞的分化。第四个是编码WD重复蛋白的srwl^+。缺乏该基因的细胞无法开始分化，对arrestin G1和DefectiveG2的控制较差。Cig2细胞周期蛋白基因的缺失抑制了细胞不能启动分化的过程，我们之前发现cig2细胞周期蛋白基因是分化的负调控因子。分析表明，srwl^+在营养饥饿诱导的有丝分裂周期蛋白CDc13的降解中是必不可少的。因此，srwl^+是细胞增殖和分化之间转换的关键因素。较少

During this research term, we have focused on the identification of new elements regulating onset of differentiation of fission yeast and isolated 4 such elements playing key roles regulating the onset of differentiation and switching growth and differentiation. One is phhl^+ encoding a stress MAP kinase highly homologous with mammalian p38. Analysis shows that phhl is required for nutrient starvation-invokes induction of Ste11, a key transcriptional factor essential for the onset of differentiation, providing a molecular basis for the promotion of differentiation by stress. The second is rcdl^+ whose structural homologues are present at least in budding yeast, plant, nematodes and humans. rcdl^+ is essential for nitrogen starvation-invoked differentiation and Ste11 induction. The human homologue of rcdl^+ is expressed abundantly in tests, ovary, spleen and thymus, where cell proliferation and differentiation are actively taking place. The third is nrdl^+ encoding a typical RNA binding … More protein. Analysis shows that the biological role of this gene is to inhibit differentiation by repressing Ste11-regulated genes essential for conjugation and/or meiosis until cells reach a critical point of starvation. We also isolated rat and human homologues of nrdl^+ by expression cloning using fission yeast as host. They are named ROD1. As far as assayd in fission yeast, ROD1 is functionally indistinguishable from nrdl^+. Overexpression of ROD1 in a human hematopietic cell line effectively blocks its differentiation to megakaryocytes.The fourth is srwl^+ encoding a WD repeat protein. Cells lacking this gene are unable to start differentiation, poor to arrestin G1 and defectivein G2 control. The inability to start differentiation is suppressed by deletion of the cig2 cyclin gene, which we previously identified as a negative regulator of differentiation. Analysis shows that srwl^+ is essential for nutrient starvation-induced degradation of the Cdc13 mitotic cyclin. Thus, srwl^+ is a key factor switching between cell proliferation and differentiation. Less