Mechanisms of formation and destruction of the contractile ring during cytokinesis

我们用各种细胞分析了收缩环的形成机制。在分裂酵母细胞中，收缩环由在核分裂期间积累在细胞的中间区域的F-肌动蛋白电缆形成。在这个过程中，由F-肌动蛋白电缆和从该结构延伸的前导电缆组成的紫菀状结构是重要的。Cdc 12在前导索的伸长中起作用，而Cdc 15在F-肌动蛋白索与前导索的融合中起作用。我们还分析了Rho蛋白在裂殖酵母中的功能，发现了一个新的G蛋白Rho 3。Rho 3定位于细胞膜上，在Rho 3和Cdc 42的下游发现了一个新的家族蛋白For 3。Rho 3和For 3控制肌动蛋白细胞骨架和微管，从而调节细胞的形状和胞质分裂的位置。Cla 4（PAK）和Bni 1（Bni）在芽殖酵母中协同调节septin环。F-肌动蛋白起重要作用， ...更多信息 在这一过程中的重要作用。在四膜虫中，二聚体EF 1a束F-肌动蛋白。Ca/钙调素解离这种EF 1a二聚体，从而抑制F-肌动蛋白的成束。四膜虫fimalgae结合和捆绑F-肌动蛋白在钙不敏感的方式。它位于卵裂沟。我们发现，肌动蛋白在海胆胚胎第四次分裂时，在中心体附近的皮质中浓度较低，而在远离中心体的皮质中浓度较高，在那里形成了沟。分析了非洲爪蟾卵中微管在收缩环形成中的作用。微管毒素对微管的破坏并不影响收缩环的收缩，但会影响其形成。我们还发现，在卵裂沟的下方，从两极发出的微管相互连接。我们测试了一种可能性，钙离子在裂解信号中发挥作用，通过分析钙释放周围的分裂沟。在卵裂沟的前缘既没有钙波，也没有钙泡或钙点等钙释放。HeLa细胞中的Rho激酶与细丝蛋白A结合。因此，这些蛋白质可能共同定位在收缩环中。少

We analyzed mechanism of formation of the contractile ring using various cells. In fission yeast cells, the contractile ring is formed from F-actin cables which accumulate at the medial region of the cell during nuclear division. The aster-like structure consisting of F-actin cables and the leading cable which elongates from the structure are important in this process. Cdcl2 plays a role in elongation of the leading cable, while Cdc15 plays a role in the fusion of the F-actin cables to the leading cable. We also analyzed function of Rho proteins in fission yeast, and found a novel G-protein Rho3. Rho3 is localized to the cell membrane .It was found that a novel formin family protein For3 is present downstream of either Rho3 or Cdc42. Rho3 and For3 controls both actin cytoskeleton and microtubules, and thereby regulate shape of the cell and position of cytokinesis. Cla4(PAK) and Bni1 (formin) cooperatively function in regulation of the septin ring in budding yeast. F-actin plays an impo … More rtant role in this process. In Tetrahymena, dimeric EF1a bundles F-actin. Ca/calmodulin dissociates this EF1a dimer and thus inhibit the bundling of F-actin. Tetrahymena fimbrin binds and bundles F-actin in a Ca-insensitive manner. It is localized to the cleavage furrow. We found that actin is less concentrated in the cortex near the centrosome while concentrated in the cortex away from it, where the furrow is formed, in the fourth division in sea urchin embryos. Role of microtubules in formation of the contractile ring in Xenopus eggs was analyzed. Disruption of microtubules by microtubule poisons did not interfere with contraction of the contractile ring, but interfered with its formation. We also found that the microtubules emanated from the both poles link with each other beneath the cleavage furrow. We tested a possibility that Ca ions play a role in cleavage signaling by analyzing Ca release around the cleavage furrow. Neither Ca waves nor small Ca releases such as Ca puffs or Ca blips were found at the leading edge of the cleavage furrow. Rho-kinase in HeLa cells binds to filamin A. Thus, it is possible that these proteins co-localize in the contractile ring. Less