Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA.
Dev Cell. 2012 Jun 12;22(6):1247-60. doi: 10.1016/j.devcel.2012.04.015.
Actin filaments and myosin II are evolutionarily conserved force-generating components of the contractile ring during cytokinesis. Here we show that in budding yeast, actin filament depolymerization plays a major role in actomyosin ring constriction. Cofilin mutation or chemically stabilizing actin filaments attenuate actomyosin ring constriction. Deletion of myosin II motor domain or the myosin regulatory light chain reduced the contraction rate and also the rate of actin depolymerization in the ring. We constructed a quantitative microscopic model of actomyosin ring constriction via filament sliding driven by both actin depolymerization and myosin II motor activity. Model simulations based on experimental measurements support the notion that actin depolymerization is the predominant mechanism for ring constriction. The model predicts invariability of total contraction time regardless of the initial ring size, as originally reported for C. elegans embryonic cells. This prediction was validated in yeast cells of different sizes due to different ploidies.
肌动蛋白丝和肌球蛋白 II 是有丝分裂细胞分裂过程中收缩环的进化保守的力产生成分。在这里，我们表明在出芽酵母中，肌动蛋白丝解聚在肌球蛋白环收缩中起主要作用。丝切蛋白突变或化学稳定肌动蛋白丝会减弱肌球蛋白环的收缩。肌球蛋白 II 马达结构域或肌球蛋白调节轻链的缺失降低了环的收缩率和肌动蛋白丝的解聚速率。我们通过由肌动蛋白丝解聚和肌球蛋白 II 马达活性驱动的细丝滑动构建了肌球蛋白环收缩的定量显微镜模型。基于实验测量的模型模拟支持这样的观点，即肌动蛋白丝解聚是环收缩的主要机制。该模型预测总收缩时间的不变性，而与初始环大小无关，如最初报道的秀丽隐杆线虫胚胎细胞。由于不同的倍性，该预测在不同大小的酵母细胞中得到了验证。
