From the Institute of Biomedical Sciences, Academia Sinica, 128 Sec. 2, Academia Road, Taipei 115, Taiwan.
From the Institute of Biomedical Sciences, Academia Sinica, 128 Sec. 2, Academia Road, Taipei 115, Taiwan
J Biol Chem. 2014 May 30;289(22):15319-27. doi: 10.1074/jbc.M114.552273. Epub 2014 Apr 24.
Human Mps1 (hMps1) is a mitotic checkpoint kinase responsible for sensing the unattached and tensionless kinetochore. Despite its importance in safeguarding proper chromosome segregation, how hMps1 is recruited to the kinetochore remains incompletely understood. Here, we demonstrate that phosphorylation at Thr-288 by the cell cycle checkpoint kinase CHK2 is involved in this process. We discovered that the phosphorylation-deficient T288A mutant has an impaired ability to localize to the kinetochore and cannot reestablish the mitotic checkpoint in hMps1-depleted cells. In support, we found that nocodazole induced hMps1 phosphorylation at the previously identified CHK2 site Thr-288 and that this could be detected at the kinetochore in a CHK2-dependent manner. Mechanistically, phosphorylation at Thr-288 promoted the interaction with the KMN (KNL1-Mis12-Ndc80 network) protein HEC1. Forced kinetochore localization corrected the defects associated with the T288A mutant. Our results provide evidence of a newly identified hMps1 phosphorylation site that is involved in the mitotic checkpoint and that CHK2 contributes to chromosomal stability through hMps1.
人源 Mps1（hMps1）是一种有丝分裂检查点激酶，负责感知无连接和无张力的动粒。尽管它在保障正确的染色体分离方面非常重要，但 hMps1 如何被招募到动粒仍然不完全清楚。在这里，我们证明细胞周期检查点激酶 CHK2 对 Thr-288 的磷酸化参与了这一过程。我们发现磷酸化缺陷的 T288A 突变体在定位到动粒方面的能力受损，并且不能在 hMps1 耗尽的细胞中重新建立有丝分裂检查点。支持这一观点的是，我们发现长春花碱诱导了先前鉴定的 CHK2 位点 Thr-288 上的 hMps1 磷酸化，并且这种磷酸化可以以 CHK2 依赖的方式在动粒上检测到。从机制上讲，Thr-288 的磷酸化促进了与 KMN（KNL1-Mis12-Ndc80 网络）蛋白 HEC1 的相互作用。强迫动粒定位纠正了 T288A 突变体相关的缺陷。我们的结果提供了证据，证明 hMps1 中有一个新鉴定的磷酸化位点参与有丝分裂检查点，并且 CHK2 通过 hMps1 有助于染色体稳定性。
