Université de la Méditerranée/Aix-Marseille II, Developmental Biology Institute (IBDML), Centre National de la Recherche Scientifique UMR6216, Case 907, Campus de Luminy, 13288 Marseille, France.
J Cell Biol. 2011 Apr 4;193(1):141-54. doi: 10.1083/jcb.201101039. Epub 2011 Mar 28.
To maintain tissue architecture, epithelial cells divide in a planar fashion, perpendicular to their main polarity axis. As the centrosome resumes an apical localization in interphase, planar spindle orientation is reset at each cell cycle. We used three-dimensional live imaging of GFP-labeled centrosomes to investigate the dynamics of spindle orientation in chick neuroepithelial cells. The mitotic spindle displays stereotypic movements during metaphase, with an active phase of planar orientation and a subsequent phase of planar maintenance before anaphase. We describe the localization of the NuMA and LGN proteins in a belt at the lateral cell cortex during spindle orientation. Finally, we show that the complex formed of LGN, NuMA, and of cortically located Gαi subunits is necessary for spindle movements and regulates the dynamics of spindle orientation. The restricted localization of LGN and NuMA in the lateral belt is instructive for the planar alignment of the mitotic spindle, and required for its planar maintenance.
为了维持组织架构，上皮细胞以平面方式分裂，垂直于它们的主要极性轴。当中心体在细胞间期中重新定位于顶端时，每个细胞周期都会重新设置平面纺锤体的方向。我们使用 GFP 标记的中心体的三维实时成像来研究鸡神经上皮细胞中纺锤体方向的动力学。在有丝分裂中期，纺锤体显示出典型的运动，在后期之前，有一个主动的平面取向阶段和随后的平面维持阶段。我们描述了 NuMA 和 LGN 蛋白在纺锤体取向过程中在细胞侧皮质带上的定位。最后，我们表明 LGN、NuMA 和位于皮质的 Gαi 亚基形成的复合物对于纺锤体运动是必要的，并调节纺锤体取向的动力学。LGN 和 NuMA 在侧带上的受限定位为有丝分裂纺锤体的平面排列提供了指导，并需要其平面维持。
