Vale Ronald D, Spudich James A, Griffis Eric R
Physiology Course, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
J Cell Biol. 2009 Sep 7;186(5):727-38. doi: 10.1083/jcb.200902083. Epub 2009 Aug 31.
Signals from the mitotic spindle during anaphase specify the location of the actomyosin contractile ring during cytokinesis, but the detailed mechanism remains unresolved. Here, we have imaged the dynamics of green fluorescent protein-tagged myosin filaments, microtubules, and Kinesin-6 (which carries activators of Rho guanosine triphosphatase) at the cell cortex using total internal reflection fluorescence microscopy in flattened Drosophila S2 cells. At anaphase onset, Kinesin-6 relocalizes to microtubule plus ends that grow toward the cortex, but refines its localization over time so that it concentrates on a subset of stable microtubules and along a diffuse cortical band at the equator. The pattern of Kinesin-6 localization closely resembles where new myosin filaments appear at the cortex by de novo assembly. While accumulating at the equator, myosin filaments disappear from the poles of the cell, a process that also requires Kinesin-6 as well as possibly other signals that emanate from the elongating spindle. These results suggest models for how Kinesin-6 might define the position of cortical myosin during cytokinesis.
后期有丝分裂纺锤体发出的信号决定了胞质分裂期间肌动球蛋白收缩环的位置，但其详细机制仍未解决。在这里，我们使用全内反射荧光显微镜，对扁平的果蝇S2细胞皮质中绿色荧光蛋白标记的肌球蛋白丝、微管和驱动蛋白6（携带 Rho 鸟苷三磷酸酶激活剂）的动态进行了成像。在后期开始时，驱动蛋白6重新定位到向皮质生长的微管正端，但随着时间的推移，其定位会得到优化，使其集中在一部分稳定的微管上，并沿着赤道处的一条弥散的皮质带分布。驱动蛋白6的定位模式与新的肌球蛋白丝通过从头组装出现在皮质的位置非常相似。在赤道处积累时，肌球蛋白丝从细胞两极消失，这一过程也需要驱动蛋白6以及可能来自伸长纺锤体的其他信号。这些结果为驱动蛋白6在胞质分裂期间如何确定皮质肌球蛋白的位置提出了模型。
