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Molecular mechanisms, for cell cycle restart from a quiescent phase in fission yeast

裂殖酵母细胞周期从静止期重新启动的分子机制

基本信息

批准号：
11680706
负责人：
SHIMODA Chikashi
金额：
$ 2.18万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11680706/
关键词：
germination sporulation cdc2 kinase cyclin cdk inhibitor cAMP spore wall pollen allergen 細胞極性アクチン

项目摘要

1) Signal transduction required for spore germination.: Germination of ascospores in the fission yeast Schizosaccharomyces pombe are induced by glucose. The intracellular cAMP level increased transiently by the addition of glucose. Furthermore, we found that mutations in the cyrl and pkal genes, encoding adenylyl cyclase and A-kinase, respectively, blocked the initiation of spore germination. Breaking of dormancy of spores requires activation of the cAMP/PKA signal pathway.2) Cell cycle progression during spore outgrowth : A cell cycle following spore germination was studied. Germinated spores enter the S phase after a long (〜10 hours) G1 phase. Cd2 kinase activity increased shortly before the onset of DNA replication. Coincidently, Cig2 cyclin was accumulated and Ruml Cdk inhibitor was disappeared. In contrast, Cdc13 cyclin is not necessary for S phase. During the G1 phase, expansion growth followed by polar growth occurs. We speculate that the long G1 phase is required for cells to reach a critical cell size necessary for the onset of S phase.3) Identification of a major spore wall protein p23 : Germination is thought to accompany chemical and morphological alteration of spore envelopes. We found that p23, a major spore wall protein, decreased gradually during germination. P23 was purified and its partial amino acid sequence was determined. This sequence was identical with the amino terminus of the isp3/meu4 gene product, The isp3 gene is transcribed during meiosis and its disruption results in reduction of sporulation ability.Isp3-GFP fusion protein localized to the spore envelope. Intriguingly, P23/Isp3 shares a characteristic alanine-rich region with pollen allergen proteins.

1)孢子萌发所需的信号传导。：裂殖酵母裂殖酵母中的子囊孢子的萌发是由葡萄糖诱导的。加入葡萄糖后，细胞内cAMP水平瞬时升高。此外，我们发现，突变的pkal和pkal基因，分别编码腺苷酸环化酶和A-激酶，阻断孢子萌发的启动。打破孢子休眠需要激活cAMP/PKA信号通路。2）孢子生长过程中的细胞周期进程：研究了孢子萌发后的细胞周期。萌发的孢子在长时间（约10小时）的G1期后进入S期。Cd 2激酶活性在DNA复制开始前不久增加。与此同时，Ruml Cdk抑制剂消失，而cyclin β 2表达增加。相反，Cdc 13 cyclin对于S期不是必需的。在G1期，发生膨胀生长，然后是极性生长。我们推测，长的G1期是细胞达到S期开始所必需的临界细胞大小所必需的。3）鉴定一种主要的孢子壁蛋白p23：萌发被认为伴随着孢子包膜的化学和形态改变。我们发现，p23，一个主要的孢子壁蛋白，在萌发过程中逐渐下降。纯化P23蛋白并测定其部分氨基酸序列。该序列与isp 3/meu 4基因产物的氨基端序列一致，isp 3基因在减数分裂过程中转录，其缺失导致孢子形成能力降低，Isp 3-GFP融合蛋白定位于孢子囊膜。有趣的是，P23/Isp 3与花粉过敏原蛋白共享一个特征性的富含丙氨酸的区域。