Department of Biological Sciences, University of Toledo, 2801 W. Bancroft Street, MS 601, Toledo, OH 43606, USA.
J Cell Biochem. 2010 Dec 1;111(5):1291-8. doi: 10.1002/jcb.22853.
The chromosomal passenger complex consisting of Borealin, INCENP, Survivin, and Aurora B follows a dynamic pattern of localization to perform its role as a regulator of chromosome alignment, aspects of the spindle assembly checkpoint, and cytokinesis. Post-translational modifications of chromosomal passenger proteins play an important role in regulating the localization and function of the complex. Borealin displays a slower electrophoretic mobility during mitosis as a result of phosphorylation. Here we show that phosphorylation at S219 is responsible for this mobility shift. An S219A mutant of Borealin that cannot be phosphorylated at this site displays a defect in centromere localization that is evident in cells arrested in mitosis with nocodazole. Further, the S219A form of Borealin is unable to efficiently rescue mitotic defects that occur upon knock-down of the endogenous protein. These defects are correlated with a reduction in the intensity of Mad2 staining at kinetochores in cells expressing the S219A form of Borealin. These results highlight an important role for phosphorylation of Borealin at S219 in the proper progression through mitosis.
由 Borealin、INCENP、Survivin 和 Aurora B 组成的染色体乘客复合物遵循动态定位模式，以发挥其作为染色体对齐、纺锤体组装检查点和胞质分裂调节因子的作用。染色体乘客蛋白的翻译后修饰在调节复合物的定位和功能方面起着重要作用。Borealin 在有丝分裂期间由于磷酸化而显示出较慢的电泳迁移率。在这里，我们表明 S219 的磷酸化是导致这种迁移率改变的原因。在该位点不能磷酸化的 Borealin S219A 突变体在用 nocodazole 阻滞的有丝分裂细胞中显示出着丝粒定位缺陷。此外，Borealin 的 S219A 形式不能有效地挽救内源蛋白敲低时发生的有丝分裂缺陷。这些缺陷与在表达 Borealin S219A 形式的细胞中，Mad2 在动粒上的染色强度降低有关。这些结果突出了 Borealin 在 S219 处磷酸化在有丝分裂过程中的适当进展中的重要作用。
