Sawin K E, Nurse P
Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom.
J Cell Biol. 1998 Jul 27;142(2):457-71. doi: 10.1083/jcb.142.2.457.
To investigate the role of microtubules in regulating cell polarity in Schizosaccharomyces pombe, we have developed a system in which normally cylindrical fission yeast synchronously form branched cells at high frequency upon treatment with the microtubule-depolymerizing drug thiabendazole (TBZ). Branching depends on both elevated temperature and cell cycle state and occurs at high frequency only when TBZ is added to cells that have not yet passed through New-End Take-Off (NETO), the normal transition from monopolar to bipolar growth. This suggests that microtubules may be of greatest physiological importance for the maintenance of cell shape at specific points in the cell cycle. The localization of three different proteins normally found at cell ends-cortical F-actin, tea1, and an ral3 (scd2)-green fluorescent protein (GFP) fusion-is disrupted by TBZ treatment. However, these proteins can eventually return to cell ends in the absence of microtubules, indicating that although their localization to ends normally depends on microtubules, they may recover by alternative mechanisms. In addition, TBZ induces a shift in ral3-GFP distribution from cell ends to the cell middle, suggesting that a protein complex containing ral3 may be part of the cue that specifies the position of branch formation.
为了研究微管在粟酒裂殖酵母细胞极性调控中的作用，我们开发了一个系统，在该系统中，正常呈圆柱形的裂殖酵母在用微管解聚药物噻苯咪唑（TBZ）处理后会高频同步形成分支细胞。分支的形成依赖于升高的温度和细胞周期状态，并且只有当TBZ添加到尚未经历新端起始（NETO）（即从单极生长到双极生长的正常转变）的细胞中时才会高频发生。这表明微管对于在细胞周期的特定时间点维持细胞形状可能具有最大的生理重要性。正常情况下位于细胞末端的三种不同蛋白质——皮质F-肌动蛋白、tea1和ral3（scd2）-绿色荧光蛋白（GFP）融合蛋白的定位会因TBZ处理而受到破坏。然而，在没有微管的情况下，这些蛋白质最终可以回到细胞末端，这表明尽管它们正常情况下定位于末端依赖于微管，但它们可能通过其他机制恢复。此外，TBZ诱导ral3-GFP分布从细胞末端转移到细胞中部，这表明包含ral3的蛋白质复合物可能是指定分支形成位置的线索的一部分。
