TORC1 kinase and the S-phase cyclin Clb5 collaborate to promote mitotic spindle assembly and DNA replication in S. cerevisiae.
TORC1 kinase and the S-phase cyclin Clb5 collaborate to promote mitotic spindle assembly and DNA replication in S. cerevisiae.
复制标题
TORC1 激酶和 S 期细胞周期蛋白 Clb5 协同促进酿酒酵母有丝分裂纺锤体组装和 DNA 复制。
DOI：
10.1007/s00294-010-0316-0
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发表时间：
2010
期刊：
影响因子：
2.5
通讯作者：
Hood-DeGrenier,JenniferK
中科院分区：
文献类型：
--
作者：
Tran,LieuT;Wang'ondu,RuthW;Weng,JessicaB;Wanjiku,GraceW;Fong,ChiM;Kile,AndrewC;Koepp,DeannaM;Hood-DeGrenier,JenniferK
雷帕霉素靶蛋白复合物1（TORC 1）是真核细胞生长的中心调节因子，可被药物雷帕霉素抑制。在芽殖酵母Saccharomyces cerevisiae中，与TORC 1失活相关的翻译缺陷在G1的早期阶段抑制细胞周期进展，但对TORC 1在细胞周期后期的可能作用知之甚少。我们研究了缺乏S期细胞周期蛋白Clb 5（clb 5 Δ）的细胞的雷帕霉素超敏表型，作为揭示TORC 1和细胞周期调控机制之间新联系的基础。剂量抑制实验表明，clb 5 Δ雷帕霉素超敏反应反映了一种独特的Clb 5相关的细胞周期蛋白依赖性激酶（CDK）功能，该功能不能由有丝分裂细胞周期蛋白执行，并且还涉及马达蛋白，特别是驱动蛋白样蛋白Kip 3。同步细胞实验揭示了雷帕霉素诱导的前后期纺锤体组装和S期进展的缺陷，其在clb 5 Δ中比在野生型细胞中更严重，但没有明显的Rad 53依赖性检查点通路的激活。一些雷帕霉素处理的细胞有异常的纺锤体形态，但雷帕霉素没有引起微管细胞骨架的严重缺陷。我们提出了一个模型，其中TORC 1和Clb 5/CDK协调行动，以促进两个主轴组装通过涉及Kip 3和S期进展的途径。
The Target of Rapamycin complex 1 (TORC1) is a central regulator of eukaryotic cell growth that is inhibited by the drug rapamycin. In the budding yeastSaccharomyces cerevisiae, translational defects associated with TORC1 inactivation inhibit cell cycle progression at an early stage in G1, but little is known about the possible roles for TORC1 later in the cell cycle. We investigated the rapamycin-hypersensitivity phenotype of cells lacking the S phase cyclin Clb5 (clb5Δ) as a basis for uncovering novel connections between TORC1 and the cell cycle regulatory machinery. Dosage suppression experiments suggested that theclb5Δ rapamycin hypersensitivity reflects a unique Clb5-associated cyclin-dependent kinase (CDK) function that cannot be performed by mitotic cyclins and that also involves motor proteins, particularly the kinesin-like protein Kip3. Synchronized cell experiments revealed rapamycin-induced defects in pre-anaphase spindle assembly and S phase progression that were more severe inclb5Δ than in wild-type cells but no apparent activation of Rad53-dependent checkpoint pathways. Some rapamycin-treated cells had aberrant spindle morphologies, but rapamycin did not cause gross defects in the microtubule cytoskeleton. We propose a model in which TORC1 and Clb5/CDK act coordinately to promote both spindle assembly via a pathway involving Kip3 and S phase progression.