Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Dev Cell. 2011 Mar 15;20(3):342-52. doi: 10.1016/j.devcel.2011.01.008.
Proper bipolar attachment of sister kinetochores to the mitotic spindle is critical for accurate chromosome segregation in mitosis. Here we show an essential role of the formin mDia3 in achieving metaphase chromosome alignment. This function is independent of mDia3 actin nucleation activity, but is attributable to EB1-binding by mDia3. Furthermore, the microtubule binding FH2 domain of mDia3 is phosphorylated by Aurora B kinase in vitro, and cells expressing the nonphosphorylatable mDia3 mutant cannot position chromosomes at the metaphase plate. Purified recombinant mDia3 phosphorylated by Aurora B exhibits reduced ability to bind microtubules and stabilize microtubules against cold-induced disassembly in vitro. Cells expressing the phosphomimetic mDia3 mutant do not form stable kinetochore microtubule fibers; despite they are able to congress chromosomes to the metaphase plate. These findings reveal a key role for mDia3 and its regulation by Aurora B phosphorylation in achieving proper stable kinetochore microtubule attachment.
正确的姐妹染色单体向有丝分裂纺锤体的双极附着对于有丝分裂中染色体的准确分离至关重要。在这里，我们展示了formin mDia3 在实现中期染色体排列中的重要作用。该功能不依赖于 mDia3 的肌动蛋白成核活性，但归因于 mDia3 与 EB1 的结合。此外，mDia3 的微管结合 FH2 结构域在体外被 Aurora B 激酶磷酸化，并且表达不可磷酸化的 mDia3 突变体的细胞不能将染色体定位在中期板上。由 Aurora B 磷酸化的纯化重组 mDia3 表现出结合微管的能力降低，并在体外稳定微管抵抗冷诱导的解体。表达磷酸模拟 mDia3 突变体的细胞不能形成稳定的动粒微管纤维;尽管它们能够将染色体向中期板聚集。这些发现揭示了 mDia3 及其由 Aurora B 磷酸化调节在实现适当的稳定动粒微管附着中的关键作用。
