Department of Biochemistry, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
J Cell Biol. 2011 Feb 7;192(3):433-45. doi: 10.1083/jcb.201011142. Epub 2011 Jan 31.
Ndel1 has been implicated in a variety of dynein-related processes, but its specific function is unclear. Here we describe an experimental approach to evaluate a role of Ndel1 in dynein-dependent microtubule self-organization using Ran-mediated asters in meiotic Xenopus egg extracts. We demonstrate that extracts depleted of Ndel1 are unable to form asters and that this defect can be rescued by the addition of recombinant N-terminal coiled-coil domain of Ndel1. Ndel1-dependent microtubule self-organization requires an interaction between Ndel1 and dynein, which is mediated by the dimerization fragment of the coiled-coil. Full rescue by the coiled-coil domain requires LIS1 binding, and increasing LIS1 concentration partly rescues aster formation, suggesting that Ndel1 is a recruitment factor for LIS1. The interactions between Ndel1 and its binding partners are positively regulated by phosphorylation of the unstructured C terminus. Together, our results provide important insights into how Ndel1 acts as a regulated scaffold to temporally and spatially regulate dynein.
Ndel1 参与了多种与动力蛋白相关的过程,但它的具体功能尚不清楚。在这里,我们描述了一种实验方法,用于使用 Ran 介导的有丝分裂非洲爪蟾卵提取物中的星体来评估 Ndel1 在动力蛋白依赖性微管自组织中的作用。我们证明,耗尽 Ndel1 的提取物无法形成星体,并且可以通过添加重组 N 端卷曲螺旋结构域的 Ndel1 来挽救这种缺陷。Ndel1 依赖性微管自组织需要 Ndel1 和动力蛋白之间的相互作用,这是由卷曲螺旋结构域的二聚化片段介导的。卷曲螺旋结构域的完全挽救需要 LIS1 结合,并且增加 LIS1 浓度部分挽救星体形成,表明 Ndel1 是 LIS1 的募集因子。Ndel1 与其结合伴侣之间的相互作用受到无结构 C 末端磷酸化的正向调节。总之,我们的结果提供了重要的见解,说明 Ndel1 如何作为一个调节支架来暂时和空间调节动力蛋白。