Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, 3584 CT, the Netherlands.
Department of Biochemistry, the Netherlands Cancer Institute, Amsterdam, 1066 CX, the Netherlands.
Cell Rep. 2019 Feb 19;26(8):2101-2112.e6. doi: 10.1016/j.celrep.2019.01.017.
Faithful chromosome segregation relies on the ability of the spindle assembly checkpoint (SAC) to delay anaphase onset until chromosomes are attached to the mitotic spindle via their kinetochores. MPS1 kinase is recruited to kinetochores to initiate SAC signaling and is removed from kinetochores once stable microtubule attachments have been formed to allow normal mitotic progression. Here, we show that a helical fragment within the kinetochore-targeting N-terminal extension (NTE) module of MPS1 is required for interactions with kinetochores and forms intramolecular interactions with its adjacent tetratricopeptide repeat (TPR) domain. Bypassing this NTE-TPR interaction results in high MPS1 levels at kinetochores due to loss of regulatory input into MPS1 localization, inefficient MPS1 delocalization upon microtubule attachment, and SAC silencing defects. These results show that SAC responsiveness to attachments relies on regulated intramolecular interactions in MPS1 and highlight the sensitivity of mitosis to perturbations in the dynamics of the MPS1-NDC80-C interactions.
染色体的正确分离依赖于纺锤体组装检查点（SAC）的能力，该检查点可以延迟后期起始，直到染色体通过动粒附着到有丝分裂纺锤体上。MPS1 激酶被募集到动粒上以启动 SAC 信号转导，一旦形成稳定的微管连接，就会从动粒上移除，以允许正常的有丝分裂进程。在这里，我们表明 MPS1 的动粒靶向 N 端延伸（NTE）模块中的螺旋片段对于与动粒的相互作用是必需的，并且与相邻的四肽重复（TPR）结构域形成分子内相互作用。绕过这个 NTE-TPR 相互作用会导致 MPS1 在动粒上的水平升高，这是由于对 MPS1 定位的调节输入丢失、微管附着后 MPS1 去定位效率低下以及 SAC 沉默缺陷所致。这些结果表明，SAC 对连接的响应依赖于 MPS1 中的调节分子内相互作用，并突出了有丝分裂对 MPS1-NDC80-C 相互作用动力学扰动的敏感性。
