Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany.
Center for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Belgrade, Serbia.
Nat Cell Biol. 2019 Sep;21(9):1138-1151. doi: 10.1038/s41556-019-0382-6. Epub 2019 Sep 2.
One of the first steps in mitotic spindle assembly is the dissolution of the centrosome linker followed by centrosome separation driven by EG5, a tetrameric plus-end-directed member of the kinesin-5 family. However, even in the absence of the centrosome linker, the two centrosomes are kept together by an ill-defined microtubule-dependent mechanism. Here we show that KIFC3, a minus-end-directed kinesin-14, provides microtubule-based centrosome cohesion. KIFC3 forms a homotetramer that pulls the two centrosomes together via a specific microtubule network. At mitotic onset, KIFC3 activity becomes the main driving force of centrosome cohesion to prevent premature spindle formation after linker dissolution as it counteracts the increasing EG5-driven pushing forces. KIFC3 is eventually inactivated by NEver in mitosis-related Kinase 2 (NEK2) to enable EG5-driven bipolar spindle assembly. We further show that persistent centrosome cohesion in mitosis leads to chromosome mis-segregation. Our findings reveal a mechanism of spindle assembly that is evolutionary conserved from yeast to humans.
有丝分裂纺锤体组装的第一步是中心体连接体的解体，随后由 EG5 驱动中心体分离，EG5 是驱动蛋白-5 家族的四聚体正极导向成员。然而，即使没有中心体连接体，两个中心体仍然通过一种定义不明确的微管依赖性机制保持在一起。在这里，我们表明，向微管负端运动的驱动蛋白-14 家族成员 KIFC3 提供了基于微管的中心体粘着。KIFC3 形成一个四聚体，通过特定的微管网络将两个中心体拉在一起。在有丝分裂开始时，KIFC3 的活性成为中心体粘着的主要驱动力，以防止在连接体解体后过早形成纺锤体，因为它抵消了不断增加的 EG5 驱动的推力。KIFC3 最终被丝裂期相关激酶 2（NEK2）失活，以允许 EG5 驱动的双极纺锤体组装。我们进一步表明，有丝分裂中持续的中心体粘着会导致染色体错误分离。我们的发现揭示了一个从酵母到人类进化保守的纺锤体组装机制。
