Romeiro Motta Mariana, Nédélec François, Saville Helen, Woelken Elke, Jacquerie Claire, Pastuglia Martine, Stolze Sara Christina, Van De Slijke Eveline, Böttger Lev, Belcram Katia, Nakagami Hirofumi, De Jaeger Geert, Bouchez David, Schnittger Arp
Department of Developmental Biology, Institute for Plant Sciences and Microbiology, University of Hamburg, Hamburg 22609, Germany; Laboratoire de Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, Lyon 69007, France.
Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
Dev Cell. 2024 Nov 18;59(22):2947-2961.e9. doi: 10.1016/j.devcel.2024.08.001. Epub 2024 Aug 26.
To ensure an even segregation of chromosomes during somatic cell division, eukaryotes rely on mitotic spindles. Here, we measured prime characteristics of the Arabidopsis mitotic spindle and built a three-dimensional dynamic model using Cytosim. We identified the cell-cycle regulator CYCLIN-DEPENDENT KINASE B1 (CDKB1) together with its cyclin partner CYCB3;1 as key regulators of spindle morphology in Arabidopsis. We found that the augmin component ENDOSPERM DEFECTIVE1 (EDE1) is a substrate of the CDKB1;1-CYCB3;1 complex. A non-phosphorylatable mutant rescue of ede1 resembled the spindle phenotypes of cycb3;1 and cdkb1 mutants and the protein associated less efficiently with spindle microtubules. Accordingly, reducing the level of augmin in simulations recapitulated the phenotypes observed in the mutants. Our findings emphasize the importance of cell-cycle-dependent phospho-control of the mitotic spindle in plant cells and support the validity of our model as a framework for the exploration of mechanisms controlling the organization of the eukaryotic spindle.
为确保在体细胞分裂过程中染色体的均匀分离，真核生物依赖有丝分裂纺锤体。在此，我们测量了拟南芥有丝分裂纺锤体的主要特征，并使用Cytosim构建了一个三维动态模型。我们鉴定出细胞周期调节因子细胞周期蛋白依赖性激酶B1（CDKB1）及其细胞周期蛋白伴侣CYCB3;1是拟南芥纺锤体形态的关键调节因子。我们发现增强子组分胚乳缺陷1（EDE1）是CDKB1;1 - CYCB3;1复合物的底物。ede1的非磷酸化突变体拯救类似于cycb3;1和cdkb1突变体的纺锤体表型，并且该蛋白与纺锤体微管的结合效率较低。因此，在模拟中降低增强子水平可重现突变体中观察到的表型。我们的研究结果强调了植物细胞中有丝分裂纺锤体的细胞周期依赖性磷酸化控制的重要性，并支持我们的模型作为探索真核纺锤体组织控制机制框架的有效性。
