A sequential multi-target Mps1 phosphorylation cascade promotes spindle checkpoint signaling
A sequential multi-target Mps1 phosphorylation cascade promotes spindle checkpoint signaling
复制标题
DOI：
10.7554/elife.22513
复制
发表时间：
2017-01-10
期刊：
影响因子：
7.7
通讯作者：
Yu, Hongtao
中科院分区：
文献类型：
--
作者：
Ji, Zhejian;Gao, Haishan;Yu, Hongtao
主纺锤体检查点激酶Mps 1感知着丝粒-微管附着并促进检查点信号传导以确保准确的染色体分离。当被Mps 1磷酸化时，动粒支架Knl 1将检查点复合物Bub 1Bub 3和BubR 1Bub 3募集到未连接的动粒。主动检查点信号传导最终增强由BubR 1Bub 3、Mad 2和Cdc 20组成的有丝分裂检查点复合物（MCC）的组装，其抑制与Cdc 20结合的后期促进复合物或细胞核小体（APC/CCdc 20）以延迟后期开始。使用体外重建，我们表明，Mps 1促进APC/C抑制MCC组件通过磷酸化Bub 1和Mad 1。磷酸化的Bub 1与Mad 1 Mad 2结合。磷酸化的Mad 1直接与Cdc 20相互作用。Bub 1或Mad 1中Mps 1磷酸化位点的突变废除了人类细胞中的纺锤体检查点。因此，Mps 1通过依次磷酸化Knl 1、Bub 1和Mad 1来促进检查点激活。这种连续的多靶点磷酸化级联反应使得检查点对Mps 1和微管结合高度敏感。
The master spindle checkpoint kinase Mps1 senses kinetochore-microtubule attachment and promotes checkpoint signaling to ensure accurate chromosome segregation. The kinetochore scaffold Knl1, when phosphorylated by Mps1, recruits checkpoint complexes Bub1Bub3 and BubR1Bub3 to unattached kinetochores. Active checkpoint signaling ultimately enhances the assembly of the mitotic checkpoint complex (MCC) consisting of BubR1Bub3, Mad2, and Cdc20, which inhibits the anaphase-promoting complex or cyclosome bound to Cdc20 (APC/CCdc20) to delay anaphase onset. Using in vitro reconstitution, we show that Mps1 promotes APC/C inhibition by MCC components through phosphorylating Bub1 and Mad1. Phosphorylated Bub1 binds to Mad1Mad2. Phosphorylated Mad1 directly interacts with Cdc20. Mutations of Mps1 phosphorylation sites in Bub1 or Mad1 abrogate the spindle checkpoint in human cells. Therefore, Mps1 promotes checkpoint activation through sequentially phosphorylating Knl1, Bub1, and Mad1. This sequential multi-target phosphorylation cascade makes the checkpoint highly responsive to Mps1 and to kinetochore-microtubule attachment.