Regulation of microtubule-based microtubule nucleation by mammalian polo-like kinase 1
Regulation of microtubule-based microtubule nucleation by mammalian polo-like kinase 1
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DOI：
10.1073/pnas.1106223108
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发表时间：
2011-07-12
影响因子：
11.1
通讯作者：
Lee, Kyung S.
中科院分区：
文献类型：
--
作者：
Johmura, Yoshikazu;Soung, Nak-Kyun;Lee, Kyung S.
双极纺锤体的形成是细胞分裂过程中有丝分裂染色体精确分离的关键。越来越多的证据表明，除了基于中心体和染色质的微管（MT）成核，基于MT的MT成核在各种真核生物中对正确的双极纺锤体形成起着重要作用。虽然最近发现的Augmin复合物似乎在这一事件中发挥了核心作用，但Augmin是如何调节的仍然未知。在这里，我们提供的证据表明，哺乳动物polo样激酶1（Plk 1）定位于有丝分裂纺锤体，并促进MT为基础的MT成核直接调节Augmin。从机制上讲，我们证明了Cdc 2依赖性磷酸化的γ-微管蛋白环复合物（γ-TuRC）招募蛋白，Nedd 1/GCP-WD，在以前未表征的S460残基诱导Nedd 1-Plk 1相互作用。这一步骤似乎是关键，使Plk 1磷酸化的Augmin复合物的Hice 1亚基，以促进Augmin-MT相互作用和MT为基础的MT从纺锤体内成核。Nedd 1 S460功能或Plk 1依赖性Hice 1磷酸化的丧失损害了Augmin-MT相互作用和γ-微管蛋白向纺锤体的募集，从而导致不适当的双极纺锤体形成，最终导致有丝分裂停滞和凋亡性细胞死亡。因此，通过Nedd 1-Plk 1复合物的形成和随后的Augmin磷酸化，Plk 1调节纺锤体基于MT的MT成核，以实现正常的双极纺锤体形成和有丝分裂进程。
Bipolar spindle formation is pivotal for accurate segregation of mitotic chromosomes during cell division. A growing body of evidence suggests that, in addition to centrosome-and chromatin-based microtubule (MT) nucleation, MT-based MT nucleation plays an important role for proper bipolar spindle formation in various eukaryotic organisms. Although a recently discovered Augmin complex appears to play a central role in this event, how Augmin is regulated remains unknown. Here we provide evidence that a mammalian polo-like kinase 1 (Plk1) localizes to mitotic spindles and promotes MT-based MT nucleation by directly regulating Augmin. Mechanistically, we demonstrated that Cdc2-dependent phosphorylation on a gamma-tubulin ring complex (gamma-TuRC) recruitment protein, Nedd1/GCP-WD, at the previously uncharacterized S460 residue induces the Nedd1-Plk1 interaction. This step appeared to be critical to allow Plk1 to phosphorylate the Hice1 subunit of the Augmin complex to promote the Augmin-MT interaction and MT-based MT nucleation from within the spindle. Loss of either the Nedd1 S460 function or the Plk1-dependent Hice1 phosphorylation impaired both the Augmin-MT interaction and gamma-tubulin recruitment to the spindles, thus resulting in improper bipolar spindle formation that ultimately leads to mitotic arrest and apoptotic cell death. Thus, via the formation of the Nedd1-Plk1 complex and subsequent Augmin phosphorylation, Plk1 regulates spindle MT-based MT nucleation to accomplish normal bipolar spindle formation and mitotic progression.