Young Sarah, Besson Sébastien, Welburn Julie P I
Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK.
Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, UK.
Biol Open. 2014 Nov 21;3(12):1217-23. doi: 10.1242/bio.201410363.
Spindle length varies dramatically across species and during early development to segregate chromosomes optimally. Both intrinsic factors, such as regulatory molecules, and extrinsic factors, such as cytoplasmic volume, determine spindle length scaling. However, the properties that govern spindle shape and whether these features can be modulated remain unknown. Here, we analyzed quantitatively how the molecular players which regulate microtubule dynamics control the kinetics of spindle formation and shape. We find that, in absence of Clasp1 and Clasp2, spindle assembly is biphasic due to unopposed inward pulling forces from the kinetochore-fibers and that kinetochore-fibers also alter spindle geometry. We demonstrate that spindle shape scaling is independent of the nature of the molecules that regulate dynamic microtubule properties, but is dependent on the steady-state metaphase spindle length. The shape of the spindle scales anisotropically with increasing length. Our results suggest that intrinsic mechanisms control the shape of the spindle to ensure the efficient capture and alignment of chromosomes independently of spindle length.
纺锤体长度在不同物种间以及早期发育过程中差异极大，以便最优地分离染色体。内在因素，如调控分子，和外在因素，如细胞质体积，共同决定纺锤体长度的缩放。然而，支配纺锤体形状的特性以及这些特征是否可以被调节仍然未知。在这里，我们定量分析了调控微管动力学的分子参与者如何控制纺锤体形成和形状的动力学。我们发现，在没有Clasp1和Clasp2的情况下，由于动粒纤维产生的无对抗向内拉力，纺锤体组装是双相的，并且动粒纤维也会改变纺锤体几何形状。我们证明，纺锤体形状缩放与调节动态微管特性的分子性质无关，但依赖于中期纺锤体的稳态长度。纺锤体形状随着长度增加呈各向异性缩放。我们的结果表明，内在机制控制纺锤体形状，以确保染色体的有效捕获和排列，而与纺锤体长度无关。
