Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan.
J Biol Chem. 2011 Feb 18;286(7):5589-98. doi: 10.1074/jbc.M110.167742. Epub 2010 Dec 16.
The dynactin complex is required for activation of the dynein motor complex, which plays a critical role in various cell functions including mitosis. During metaphase, the dynein-dynactin complex removes spindle checkpoint proteins from kinetochores to facilitate the transition to anaphase. Three components (p150(Glued), dynamitin, and p24) compose a key portion of the dynactin complex, termed the projecting arm. To investigate the roles of the dynactin complex in mitosis, we used RNA interference to down-regulate p24 and p150(Glued) in human cells. In response to p24 down-regulation, we observed cells with delayed metaphase in which chromosomes frequently align abnormally to resemble a "figure eight," resulting in cell death. We attribute the figure eight chromosome alignment to impaired metaphasic centrosomes that lack spindle tension. Like p24, RNA interference of p150(Glued) also induces prometaphase and metaphase delays; however, most of these cells eventually enter anaphase and complete mitosis. Our findings suggest that although both p24 and p150(Glued) components of the dynactin complex contribute to mitotic progression, p24 also appears to play a role in metaphase centrosome integrity, helping to ensure the transition to anaphase.
动力蛋白激活因子复合体对于激活动力蛋白复合物至关重要，后者在包括有丝分裂在内的各种细胞功能中发挥着关键作用。在中期，动力蛋白-动力蛋白激活因子复合物将纺锤体检验点蛋白从动粒上移除，从而促进向后期的转变。三个组件（p150（Glued）、动力素和 p24）组成了动力蛋白激活因子复合体的一个关键部分，称为伸出臂。为了研究动力蛋白激活因子复合体在有丝分裂中的作用，我们使用 RNA 干扰技术下调了人类细胞中的 p24 和 p150（Glued）。在 p24 下调的情况下，我们观察到细胞中期延迟，其中染色体经常异常排列，类似于“8”字形，导致细胞死亡。我们将“8”字形染色体排列归因于缺乏纺锤体张力的中期中心体受损。与 p24 一样，p150（Glued）的 RNA 干扰也会诱导前期和中期延迟；然而，这些细胞中的大多数最终进入后期并完成有丝分裂。我们的发现表明，尽管动力蛋白激活因子复合体的 p24 和 p150（Glued）两个组成部分都有助于有丝分裂的进行，但 p24 似乎也在中期中心体完整性中发挥作用，有助于确保向后期的转变。
