Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK.
J Cell Biol. 2010 Jul 12;190(1):25-34. doi: 10.1083/jcb.201002133.
Mps1 is an essential component of the spindle assembly checkpoint. In this study, we describe a novel Mps1 inhibitor, AZ3146, and use it to probe the role of Mps1's catalytic activity during mitosis. When Mps1 is inhibited before mitotic entry, subsequent recruitment of Mad1 and Mad2 to kinetochores is abolished. However, if Mps1 is inhibited after mitotic entry, the Mad1-C-Mad2 core complex remains kinetochore bound, but O-Mad2 is not recruited to the core. Although inhibiting Mps1 also interferes with chromosome alignment, we see no obvious effect on aurora B activity. In contrast, kinetochore recruitment of centromere protein E (CENP-E), a kinesin-related motor protein, is severely impaired. Strikingly, inhibition of Mps1 significantly increases its own abundance at kinetochores. Furthermore, we show that Mps1 can dimerize and transphosphorylate in cells. We propose a model whereby Mps1 transphosphorylation results in its release from kinetochores, thus facilitating recruitment of O-Mad2 and CENP-E and thereby simultaneously promoting checkpoint signaling and chromosome congression.
Mps1 是纺锤体组装检查点的一个必需组成部分。在这项研究中，我们描述了一种新型的 Mps1 抑制剂 AZ3146，并利用它来探究 Mps1 的催化活性在有丝分裂过程中的作用。在有丝分裂进入之前抑制 Mps1 时，随后 Mad1 和 Mad2 向着丝粒的募集被废除。然而，如果在有丝分裂进入之后抑制 Mps1，Mad1-C-Mad2 核心复合物仍然结合在着丝粒上，但 O-Mad2 没有被募集到核心复合物上。尽管抑制 Mps1 也会干扰染色体排列，但我们没有看到对极光激酶 B 活性的明显影响。相比之下，着丝粒募集着丝粒蛋白 E（CENP-E），一种与动力蛋白相关的运动蛋白，受到严重损害。引人注目的是，抑制 Mps1 会显著增加其在着丝粒上的丰度。此外，我们还表明，Mps1 可以在细胞内二聚化和反式磷酸化。我们提出了一个模型，即 Mps1 的反式磷酸化导致其从着丝粒上释放，从而促进 O-Mad2 和 CENP-E 的募集，从而同时促进检查点信号和染色体聚缩。
