Microtubule Function and Cell Division group, Cell and Developmental Biology Program, Centre for Genomic Regulation (CRG) and UPF, Dr. Aiguader 88, 08003 Barcelona, Spain.
J Cell Sci. 2012 Jun 15;125(Pt 12):2805-14. doi: 10.1242/jcs.092429. Epub 2012 Jun 26.
The mitotic spindle is structurally and functionally defined by its main component, the microtubules (MTs). The MTs making up the spindle have various functions, organization and dynamics: astral MTs emanate from the centrosome and reach the cell cortex, and thus have a major role in spindle positioning; interpolar MTs are the main constituent of the spindle and are key for the establishment of spindle bipolarity, chromosome congression and central spindle assembly; and kinetochore-fibers are MT bundles that connect the kinetochores with the spindle poles and segregate the sister chromatids during anaphase. The duplicated centrosomes were long thought to be the origin of all of these MTs. However, in the last decade, a number of studies have contributed to the identification of non-centrosomal pathways that drive MT assembly in dividing cells. These pathways are now known to be essential for successful spindle assembly and to participate in various processes such as K-fiber formation and central spindle assembly. In this Commentary, we review the recent advances in the field and discuss how different MT assembly pathways might cooperate to successfully form the mitotic spindle.
有丝分裂纺锤体的结构和功能由其主要成分微管（MTs）定义。构成纺锤体的 MTs 具有多种功能、组织和动态：星体 MTs 从中心体发出并到达细胞质皮层，因此在纺锤体定位中起主要作用；极间 MTs 是纺锤体的主要成分，对于建立纺锤体两极、染色体向心性聚集和中心纺锤体组装至关重要；动粒纤维是连接动粒与纺锤体两极的 MT 束，在后期将姐妹染色单体分离。长期以来，人们认为复制的中心体是所有这些 MT 的起源。然而，在过去的十年中，许多研究有助于确定驱动有丝分裂细胞中 MT 组装的非中心体途径。这些途径现在被认为对于成功组装纺锤体至关重要，并参与各种过程，如 K 纤维形成和中心纺锤体组装。在这篇评论中，我们回顾了该领域的最新进展，并讨论了不同的 MT 组装途径如何合作成功形成有丝分裂纺锤体。
