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The Bub1-Plk1 kinase complex promotes spindle checkpoint signalling through Cdc20 phosphorylation.
Nature Communications ( IF 14.7 ) Pub Date : 2016-Feb-25 , DOI: 10.1038/ncomms10818
Luying Jia 1 , Bing Li 1 , Hongtao Yu 1
Affiliation  

The spindle checkpoint senses unattached kinetochores and inhibits the Cdc20-bound anaphase-promoting complex or cyclosome (APC/C), to delay anaphase, thereby preventing aneuploidy. A critical checkpoint inhibitor of APC/C(Cdc20) is the mitotic checkpoint complex (MCC). It is unclear whether MCC suffices to inhibit all cellular APC/C. Here we show that human checkpoint kinase Bub1 not only directly phosphorylates Cdc20, but also scaffolds Plk1-mediated phosphorylation of Cdc20. Phosphorylation of Cdc20 by Bub1-Plk1 inhibits APC/C(Cdc20) in vitro and is required for checkpoint signalling in human cells. Bub1-Plk1-dependent Cdc20 phosphorylation is regulated by upstream checkpoint signals and is dispensable for MCC assembly. A phospho-mimicking Cdc20 mutant restores nocodazole-induced mitotic arrest in cells depleted of Mad2 or BubR1. Thus, Bub1-Plk1-mediated phosphorylation of Cdc20 constitutes an APC/C-inhibitory mechanism that is parallel, but not redundant, to MCC formation. Both mechanisms are required to sustain mitotic arrest in response to spindle defects.

中文翻译:


Bub1-Plk1 激酶复合物通过 Cdc20 磷酸化促进纺锤体检查点信号传导。



纺锤体检查点感知未附着的动粒并抑制 Cdc20 结合的后期促进复合物或环体 (APC/C),以延迟后期,从而防止非整倍性。 APC/C(Cdc20) 的一个关键检查点抑制剂是有丝分裂检查点复合物 (MCC)。目前尚不清楚 MCC 是否足以抑制所有细胞 APC/C。在这里,我们证明人类检查点激酶 Bub1 不仅直接磷酸化 Cdc20,而且还支架 Plk1 介导的 Cdc20 磷酸化。 Bub1-Plk1 对 Cdc20 的磷酸化可在体外抑制 APC/C(Cdc20),并且是人体细胞中检查点信号传导所必需的。 Bub1-Plk1 依赖性 Cdc20 磷酸化受上游检查点信号调节,对于 MCC 组装来说是可有可无的。在 Mad2 或 BubR1 耗尽的细胞中,模拟磷酸化的 Cdc20 突变体可恢复诺考达唑诱导的有丝分裂停滞。因此,Bub1-Plk1 介导的 Cdc20 磷酸化构成了 APC/C 抑制机制,与 MCC 形成平行但并非冗余。这两种机制都需要维持有丝分裂停滞以应对纺锤体缺陷。
更新日期:2016-02-28
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