Whitehead Institute for Biomedical Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
J Cell Biol. 2010 Oct 18;191(2):269-80. doi: 10.1083/jcb.201006129. Epub 2010 Oct 11.
During mitosis, kinetochores play multiple roles to generate interactions with microtubules, and direct chromosome congression, biorientation, error correction, and anaphase segregation. However, it is unclear what changes at the kinetochore facilitate these distinct activities. Here, we describe a complex of the spindle- and kinetochore-associated protein Astrin, the small kinetochore-associated protein (SKAP), and the dynein light chain LC8. Although most dynein-associated proteins localize to unaligned kinetochores in an Aurora B-dependent manner, Astrin, SKAP, and LC8 localization is antagonized by Aurora B such that they target exclusively to bioriented kinetochores. Astrin-SKAP-depleted cells fail to maintain proper chromosome alignment, resulting in a spindle assembly checkpoint-dependent mitotic delay. Consistent with a role in stabilizing bioriented attachments, Astrin and SKAP bind directly to microtubules and are required for CLASP localization to kinetochores. In total, our results suggest that tension-dependent Aurora B phosphorylation can act to control outer kinetochore composition to provide distinct activities to prometaphase and metaphase kinetochores.
在有丝分裂过程中，动粒发挥多种作用，与微管生成相互作用，并指导染色体的向心性移动、正确取向、错误修正和后期分离。然而，动粒发生了哪些变化，从而促进了这些不同的活动，目前尚不清楚。在这里，我们描述了纺锤体和动粒相关蛋白 Astrin、小动粒相关蛋白（SKAP）和动力蛋白轻链 LC8 的复合物。虽然大多数与动力蛋白相关的蛋白以 Aurora B 依赖性方式定位于未对准的动粒，但 Astrin、SKAP 和 LC8 的定位受到 Aurora B 的拮抗，从而使其专门靶向正确取向的动粒。Astrin-SKAP 耗尽的细胞无法维持适当的染色体对齐，导致纺锤体组装检查点依赖性有丝分裂延迟。与稳定正确取向附着的作用一致，Astrin 和 SKAP 直接与微管结合，并且需要 CLASP 定位到动粒。总的来说，我们的结果表明，张力依赖性 Aurora B 磷酸化可以控制外动粒组成，为前期和中期动粒提供不同的功能。
