Mps1 Regulates Kinetochore-Microtubule Attachment Stability via the Ska Complex to Ensure Error-Free Chromosome Segregation.
Mps1 Regulates Kinetochore-Microtubule Attachment Stability via the Ska Complex to Ensure Error-Free Chromosome Segregation.
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DOI：
10.1016/j.devcel.2017.03.025
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发表时间：
2017-04-24
影响因子：
11.8
通讯作者：
Jallepalli PV
中科院分区：
文献类型：
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作者：
Maciejowski J;Drechsler H;Grundner-Culemann K;Ballister ER;Rodriguez-Rodriguez JA;Rodriguez-Bravo V;Jones MJK;Foley E;Lampson MA;Daub H;McAinsh AD;Jallepalli PV
纺锤体组装检查点（SAC）激酶Mps1不仅抑制后期，而且纠正可能导致错误分离和非整倍体的错误附着。然而，Mps1的误差校正相关底物是未知的。使用化学调谐的着丝酶靶向测定，我们发现Mps1使微管附着物（k -纤维）上位性地与Aurora B（另一种主要的纠错激酶）不稳定。通过定量蛋白质组学，我们确定了mps1调控的外着丝点磷酸化的多个位点。底物修饰是微管敏感的，并且由稳定染色体-纺锤体附着的PP2A-B56磷酸酶反对。一致地，Mps1抑制在耗尽PP2A-B56后恢复了k纤维的稳定性。我们还发现Ska复合物是Mps1在着丝点-微管界面上的关键效应物，因为在体内，突变模拟了k纤维的组成磷酸化不稳定，并降低了Ska复合物从晶格扩散到端偶联微管结合的转化效率。我们的研究结果揭示了Mps1如何动态修改着丝点以纠正不正确的附着并确保忠实的染色体分离。
The spindle assembly checkpoint (SAC) kinase Mps1 not only inhibits anaphase but also corrects erroneous attachments that could lead to missegregation and aneuploidy. However, Mps1’s error correction-relevant substrates are unknown. Using a chemically tuned kinetochore-targeting assay, we show that Mps1 destabilizes microtubule attachments (K-fibers) epistatically to Aurora B, the other major error-correcting kinase. Through quantitative proteomics, we identify multiple sites of Mps1-regulated phosphorylation at the outer kinetochore. Substrate modification was microtubule-sensitive and opposed by PP2A-B56 phosphatases that stabilize chromosome-spindle attachment. Consistently, Mps1 inhibition rescued K-fiber stability after depleting PP2A-B56. We also identify the Ska complex as a key effector of Mps1 at the kinetochore-microtubule interface, as mutations that mimic constitutive phosphorylation destabilized K-fibers in vivo and reduced the efficiency of the Ska complex’s conversion from lattice diffusion to end-coupled microtubule binding in vitro. Our results reveal how Mps1 dynamically modifies kinetochores to correct improper attachments and ensure faithful chromosome segregation.