Cyclin dependent kinase cascade.

线粒体染色体动力学是由多种线粒体激酶的协调活动调节的，如Cdc 2（Cdkl）、Aurora-B或Polo-样激酶1 （P1 k1），但其协调仍然是未知的机制。我们演示了两部小说Cdc 2激酶级联。1）我们演示了Plkl和Vimenti-Ser 55由CDc 2磷酸化的直接相互作用，是导致Plkl激活和进一步Vimentin磷酸化的事件。体外分析揭示了Plkl磷酸化维imentin在1摩尔磷酸盐/摩尔底物中，在某些情况下，它部分地抑制了其薄膜形成能力。体外vimentin上的Plkl磷酸化Ser 82，这种磷酸化是从金属酶中提取出来的，并在mitosis结束前保留的。这一提升，随后是Cdc 2诱导的维明汀-Ser 55磷酸化。Plkl对RNA干扰的抑制抑制了维明丁-Ser 82磷酸化在线粒体中的延长。这些结果表明了一种新颖的机制，即Cdc 2调节的甲基离子体磷酸化不仅是一种直接的酶反应，而且也是Plkl回收到活性体。2）我们在中中心蛋白（INCENP）中发现Cdc 2磷酸化Thr 59和Thr 388，它们调节Aurora-B的定位和激酶活动，从prophase到metaphase。INCENP depletion disrupts Plkl本地化具体在kinetochore。此表型是由INCENP野生型（WT）和INCENP突变在Thr 59到Ala （T59 A），但不是在Thr 388到Ala （T388 A）中恢复的。The replacement of endogenous INCENP with T388A resulted in the delay of progression from metaphase to anaphage。我们提出的结论是，Cdc 2的INCENP磷酸化是必要的对Plkl到动力学的回收，以及Plkl和Aurora-B的复合形成，INCENP可能在染色动力学的调节中发挥关键作用。

Mitotic chromosomal dynamics is regulated by the coordinated activities of many mitotic kinases, such as Cdc2 (Cdkl), Aurora-B or Polo-like kinase 1 (P1k1), but mechanisms of its coordination remain unknown. We demonstrated two novel Cdc2 kinase cascades. 1) We demonstrated a direct interaction between Plkl and vimentin-Ser55 phosphorylated by Cdc2, an event which led to Plkl activation and further vimentin phosphorylation by Plkl. In vitro analyses revealed that Plkl phosphorylated vimentin at,・1 mol phosphate/mol substrate, which partly inhibited its filament forming ability. Plkl phosphorylated Ser82 on vimentin in vitro, and this phosphorylation was elevated from metaphase and was maintained until the end of mitosis. This elevation thus followed the Cdc2-induced vimentin-Ser55 phosphorylation. Depletion of Plkl by RNA interference impaired the elevation of vimentin-Ser82 phosphorylation in mitosis. These results indicated a novel mechanism that Cdc2 regulated mitotic vimentin phosphorylation via not only a direct enzyme reaction but also Plkl recruitment to vimentin. 2) We found that Cdc2 phosphorylates Thr59 and Thr388 on inner centromere protein (INCENP), which regulates localization and kinase activity of Aurora-B, from prophase to metaphase. INCENP depletion disrupts Plkl localization specifically at the kinetochore. This phenotype is rescued by the exogenous expression of INCENP wild type (WT) and INCENP mutated at Thr59 to Ala (T59A), but not at Thr388 to Ala (T388A). The replacement of endogenous INCENP with T388A resulted in the delay of progression from metaphase to anaphage. Our findings suggested that INCENP phosphorylation by Cdc2 is necessary for the recruitment of Plkl to the kinetochore, and the complex formation of Plkl and Aurora-B on INCENP may play critical roles in the regulation of chromosomal dynamics.