Laycock Joseph E, Savoian Matthew S, Glover David M
Cancer Research UK Cell Cycle Genetics Group, University of Cambridge, Department of Genetics.
J Cell Sci. 2006 Jun 1;119(Pt 11):2354-61. doi: 10.1242/jcs.02957.
The metaphase-spindle steady-state length occurs as spindle microtubules ;flux', incorporating new subunits at their plus ends, while simultaneously losing subunits from their minus ends. Orbit/Mast/CLASP is required for tubulin subunit addition at kinetochores, and several kinesins regulate spindle morphology and/or flux by serving as microtubule depolymerases. Here, we use RNA interference in S2 cells to examine the relationship between Orbit and the four predicted kinesin-type depolymerases encoded by the Drosophila genome (Klp10A, Klp59C, Klp59D and Klp67A). Single depletion of Orbit results in monopolar spindles, mitotic arrest and a subsequent increase in apoptotic cells. These phenotypes are rescued by co-depleting Klp10A but none of the other three depolymerases. Spindle bipolarity is restored by preventing the spindle collapse seen in cells that lack Orbit, leading to functional spindles that are similar to controls in shape and length. We conclude that Klp10A exclusively antagonises Orbit in the regulation of bipolar spindle formation and maintenance.
中期纺锤体的稳态长度出现在纺锤体微管“通量”过程中，微管在其正端并入新的亚基，同时在负端失去亚基。着丝粒处微管蛋白亚基的添加需要Orbit/Mast/CLASP，并且几种驱动蛋白作为微管解聚酶来调节纺锤体形态和/或通量。在这里，我们利用RNA干扰S2细胞来研究Orbit与果蝇基因组编码的四种预测的驱动蛋白型解聚酶（Klp10A、Klp59C、Klp59D和Klp67A）之间的关系。单独缺失Orbit会导致单极纺锤体、有丝分裂停滞以及随后凋亡细胞的增加。通过共同缺失Klp10A可以挽救这些表型，但其他三种解聚酶则不能。通过防止缺乏Orbit的细胞中出现的纺锤体塌陷来恢复纺锤体双极性，从而产生在形状和长度上与对照相似的功能性纺锤体。我们得出结论，在双极纺锤体形成和维持的调节中，Klp10A专门拮抗Orbit。
