Cortical capture of microtubules and spindle polarity in budding yeast - where's the catch?
Cortical capture of microtubules and spindle polarity in budding yeast - where's the catch?
复制标题
DOI：
10.1242/jcs.01650
复制
发表时间：
2005-02-01
影响因子：
4
通讯作者：
Segal, M
中科院分区：
文献类型：
--
作者：
Huisman, SM;Segal, M
在不对称分裂中，有丝分裂纺锤体必须根据细胞极性轴对齐。这是通过将从每个纺锤体极发出的星体微管靶向相对的细胞皮层区室来实现的。酿酒酵母是解析这一复杂过程的强大遗传模型。对这种酵母的深入研究为连接肌动蛋白组织和沿着母芽轴的纺锤体方向的程序提供了详细的模型。该程序需要 Kar9p（一种沿着极化肌动蛋白电缆引导微管的蛋白质）和极性决定因子 Bud6p/Aip3（标记芽尖和芽颈处的皮质捕获位点）的单独贡献。更复杂的是，细胞周期蛋白依赖性激酶 (Cdk) 差异性地调节纺锤体极功能，以决定不对称纺锤体极的命运。由纺锤体极建立的不对称接触赋予了另一层外在不对称性，限制了 Kar9p 招募到前往子细胞的极。结果，在纺锤体组装后，来自单极的星体微管被引导至芽室。最后，Cdk 还可能与 Kar9p 一起沿着星体微管易位，以调节纺锤体排列后的微管-皮质相互作用。有丝分裂纺锤体插入芽颈是由微管运动动力蛋白驱动的。该过程依赖于微管加末端跟踪蛋白和驱动蛋白的联合作用，驱动蛋白控制微管加末端的细胞周期依赖性动力蛋白丰度。因此，这种与肌动蛋白无关的纺锤体定向途径也可能受到 Cdk 的影响。
In asymmetric divisions, the mitotic spindle must align according to the cell polarity axis. This is achieved through targeting astral microtubules emanating from each spindle pole to opposite cell cortex compartments. Saccharomyces cerevisiae is a powerful genetic model for dissection of this complex process. Intense research in this yeast has rendered detailed models for a program linking actin organization and spindle orientation along the mother-bud axis. This program requires the separate contributions of Kar9p, a protein guiding microtubules along polarized actin cables, and the polarity determinant Bud6p/Aip3 that marks sites for cortical capture at the bud tip and bud neck. In an added layer of complexity, cyclin-dependent kinase (Cdk) differentially regulates spindle pole function to dictate asymmetric spindle pole fate. Asymmetric contacts established by the spindle poles impart a further layer of extrinsic asymmetry restricting recruitment of Kar9p to the pole destined for the daughter cell. As a result, astral microtubules from a single pole are guided to the bud compartment after spindle assembly. Finally, Cdk might also translocate along astral microtubules in association with Kar9p to modulate microtubule-cortex interactions following spindle alignment. Insertion of the mitotic spindle into the bud neck is driven by the microtubule motor dynein. This process relies on the combined action of microtubule-plus-end-tracking proteins and kinesins that control the cell-cycle-dependent abundance of dynein at microtubule plus ends. Thus, this actin-independent pathway for spindle orientation might also be influenced by Cdk.