Roles of Formin Nodes and Myosin Motor Activity in Mid1p-dependent Contractile-Ring Assembly during Fission Yeast Cytokinesis
Roles of Formin Nodes and Myosin Motor Activity in Mid1p-dependent Contractile-Ring Assembly during Fission Yeast Cytokinesis
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DOI：
10.1091/mbc.e09-05-0428
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发表时间：
2009-12-15
影响因子：
3.3
通讯作者：
Wu, Jian-Qiu
中科院分区：
文献类型：
--
作者：
Coffman, Valerie C.;Nile, Aaron H.;Wu, Jian-Qiu
两个流行的模型已经出现，以解释在裂殖酵母裂殖酵母胞质分裂过程中的收缩环组装的机制：点/领先的电缆模型和搜索，捕获，拉，和释放（SCPR）模型。我们测试了这两个模型的一些基本假设。SCPR模型的Monte Carlo模拟要求在> 30个节点中存在Cdc 12 p，肌动蛋白丝从这些节点成核并被邻近节点中的肌球蛋白II捕获。肌球蛋白发动机产生的力将节点拉在一起，形成一个紧凑的收缩环。表达Cdc 12 p荧光融合蛋白的细胞的活体显微镜首次显示Cdc 12 p定位于30-50个动态节点的宽带，其中肌动蛋白丝以随机方向成核。建议的祖点，必不可少的点/领先的电缆模型，通常消失没有成核肌动蛋白丝。α-辅肌动蛋白ain 1缺失细胞在缺乏斑点的情况下通过结节形成正常的收缩环。基于myo 2-E1和UCS rng 3 -65突变体中较慢或不存在的节点凝聚，需要肌球蛋白运动活性来将节点凝聚成收缩环。总之，这些数据为胞质分裂中收缩环形成的SCPR模型提供了强有力的支持。
Two prevailing models have emerged to explain the mechanism of contractile-ring assembly during cytokinesis in the fission yeast Schizosaccharomyces pombe: the spot/leading cable model and the search, capture, pull, and release (SCPR) model. We tested some of the basic assumptions of the two models. Monte Carlo simulations of the SCPR model require that the formin Cdc12p is present in > 30 nodes from which actin filaments are nucleated and captured by myosin-II in neighboring nodes. The force produced by myosin motors pulls the nodes together to form a compact contractile ring. Live microscopy of cells expressing Cdc12p fluorescent fusion proteins shows for the first time that Cdc12p localizes to a broad band of 30-50 dynamic nodes, where actin filaments are nucleated in random directions. The proposed progenitor spot, essential for the spot/leading cable model, usually disappears without nucleating actin filaments. alpha-Actinin ain1 deletion cells form a normal contractile ring through nodes in the absence of the spot. Myosin motor activity is required to condense the nodes into a contractile ring, based on slower or absent node condensation in myo2-E1 and UCS rng3-65 mutants. Taken together, these data provide strong support for the SCPR model of contractile-ring formation in cytokinesis.