Whitehead C M, Rattner J B
Department of Medical Biochemistry, University of Calgary, Calgary, Alberta, Canada.
J Cell Sci. 1998 Sep;111 ( Pt 17):2551-61. doi: 10.1242/jcs.111.17.2551.
The BimC family of kinesin like proteins are involved in spindle dynamics in a wide variety of organisms. The human member of this family, HsEg5, has been implicated in centrosome separation during prophase/prometaphase and in the organization of in vitro mitotic asters. HsEg5 displays a complex distribution during mitosis, associating with the centrosomes, spindle microtubules, specific regions of the intracellular bridge and a microtubule bundle that forms in association with the post-mitotic migration of the centrosome. In an effort to determine the function of HsEg5 during late mitotic events and refine its proposed function during early mitotic centrosome separation, we microinjected antibodies specific to HsEg5 into HeLa cells during various stages of mitosis. In the presence of HsEg5 antibodies we find that the microtubule arrays responsible for both pre- and post-mitotic centrosome movement never form. Similarly, the microtubule bundle within the intracellular bridge becomes prematurely altered following karyokinesis resulting in the loss of the microtubule array at either end of the bridge. In addition, some peri-centrosomal material at the spindle poles becomes fragmented and the distribution of the spindle protein NuMA becomes more concentrated at the minus ends of the spindle microtubules. Our study also provides direct evidence that there is a link between post-mitotic centrosome migration and Golgi complex positioning and reformation following mitosis. We conclude that HsEg5 plays a recurrent role in establishing and/or determining the stability of specific microtubule arrays that form during cell division and that this role may encompass the ability of HsEg5 to influence the distribution of other protein components associated with cell division
驱动蛋白样蛋白的BimC家族参与了多种生物体中的纺锤体动力学过程。该家族的人类成员HsEg5，已被证明在前期/前中期的中心体分离以及体外有丝分裂星状体的组织过程中发挥作用。HsEg5在有丝分裂过程中呈现出复杂的分布模式，与中心体、纺锤体微管、细胞内桥的特定区域以及与中心体有丝分裂后迁移相关联形成的微管束有关。为了确定HsEg5在有丝分裂后期事件中的功能，并细化其在有丝分裂早期中心体分离过程中所提出的功能，我们在有丝分裂的各个阶段将针对HsEg5的特异性抗体显微注射到HeLa细胞中。在存在HsEg5抗体的情况下，我们发现负责有丝分裂前和有丝分裂后中心体移动的微管阵列从未形成。同样，核分裂后细胞内桥中的微管束会过早改变，导致桥两端的微管阵列丢失。此外，纺锤体极处的一些中心体周围物质会碎片化，纺锤体蛋白NuMA的分布会更集中在纺锤体微管的负端。我们的研究还提供了直接证据，表明有丝分裂后中心体迁移与有丝分裂后高尔基体复合体的定位和重新形成之间存在联系。我们得出结论，HsEg5在建立和/或确定细胞分裂过程中形成的特定微管阵列的稳定性方面发挥着反复作用，并且这一作用可能包括HsEg5影响与细胞分裂相关的其他蛋白质成分分布的能力。
