Gabrielli B G, De Souza C P, Tonks I D, Clark J M, Hayward N K, Ellem K A
Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, Bancroft Centre, Brisbane, Australia.
J Cell Sci. 1996 May;109 ( Pt 5):1081-93. doi: 10.1242/jcs.109.5.1081.
The formation of the mitotic spindle is an essential prerequisite for successful mitosis. The dramatic changes in the level of microtubule (Mt) nucleation at the centrosomes and Mt dynamics that occur in prophase are presumed to be initiated through the activity of cdc2/cyclin B. Here we present data that the cdc25B isoform functions to activate the cytoplasmic pool of cdc2/cyclin B responsible for these events. In contrast to cdc25C, cdc25B is present at low levels in HeLa cells during interphase, but sharply increases in prophase, when cdc25B accumulation in the cytoplasm correlates with prophase spindle formation. Overexpression of wild type and dominant negative mutants of cdc25B and cdc25C shows that prophase Mt nucleation is a consequence of cytoplasmic cdc25B activity, and that cdc25C regulates nuclear G2/M events. Our data also suggest that the functional status of the centrosome can regulate nuclear mitotic events.
有丝分裂纺锤体的形成是成功进行有丝分裂的必要前提。中心体处微管（Mt）成核水平的显著变化以及前期发生的Mt动力学变化被认为是通过cdc2/细胞周期蛋白B的活性启动的。在此，我们展示的数据表明，cdc25B亚型的功能是激活负责这些事件的细胞质池中的cdc2/细胞周期蛋白B。与cdc25C不同，cdc25B在间期的HeLa细胞中含量较低，但在前期急剧增加，此时cdc25B在细胞质中的积累与前期纺锤体形成相关。cdc25B和cdc25C野生型及显性负性突变体的过表达表明，前期Mt成核是细胞质cdc25B活性的结果，并且cdc25C调节核G2/M期事件。我们的数据还表明，中心体的功能状态可以调节核有丝分裂事件。
