Department of Life Sciences, 2 Graduate Institute of Molecular Biology, 3 Graduate Institute of Biomedical Sciences, 4 Agricultural Biotechnology Center, and 5 Rong-Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung 40227, Taiwan.
J Cell Biol. 2014 Jan 6;204(1):19-28. doi: 10.1083/jcb.201306083. Epub 2013 Dec 30.
Mitotic spindles are microtubule-based structures, but increasing evidence indicates that filamentous actin (F-actin) and F-actin-based motors are components of these structures. ADD1 (adducin-1) is an actin-binding protein that has been shown to play important roles in the stabilization of the membrane cortical cytoskeleton and cell-cell adhesions. In this study, we show that ADD1 associates with mitotic spindles and is crucial for proper spindle assembly and mitotic progression. Phosphorylation of ADD1 at Ser12 and Ser355 by cyclin-dependent kinase 1 enables ADD1 to bind to myosin-X (Myo10) and therefore to associate with mitotic spindles. ADD1 depletion resulted in distorted, elongated, and multipolar spindles, accompanied by aberrant chromosomal alignment. Remarkably, the mitotic defects caused by ADD1 depletion were rescued by reexpression of ADD1 but not of an ADD1 mutant defective in Myo10 binding. Together, our findings unveil a novel function for ADD1 in mitotic spindle assembly through its interaction with Myo10.
有丝分裂纺锤体是微管为基础的结构，但越来越多的证据表明丝状肌动蛋白（F-actin）和基于 F-actin 的分子马达是这些结构的组成部分。ADD1（整联蛋白-1）是一种肌动蛋白结合蛋白，已被证明在稳定细胞膜皮质细胞骨架和细胞-细胞黏附中发挥重要作用。在这项研究中，我们表明 ADD1 与有丝分裂纺锤体相关联，对于正确的纺锤体组装和有丝分裂进程至关重要。细胞周期蛋白依赖性激酶 1 对 ADD1 的 Ser12 和 Ser355 的磷酸化使 ADD1 能够与肌球蛋白-X（Myo10）结合，从而与有丝分裂纺锤体相关联。ADD1 耗竭导致纺锤体扭曲、拉长和多极化，并伴有染色体排列异常。值得注意的是，通过重新表达 ADD1 而不是不能与 Myo10 结合的 ADD1 突变体，可以挽救由 ADD1 耗竭引起的有丝分裂缺陷。总之，我们的研究结果揭示了 ADD1 通过与 Myo10 的相互作用在有丝分裂纺锤体组装中的新功能。
