Maddox Amy Shaub, Lewellyn Lindsay, Desai Arshad, Oegema Karen
Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine (UCSD), CMM-East Rm. 3053, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Dev Cell. 2007 May;12(5):827-35. doi: 10.1016/j.devcel.2007.02.018.
During cytokinesis, constriction of a cortical contractile ring generates a furrow that partitions one cell into two. The contractile ring contains three filament systems: actin, bipolar myosin II filaments, and septins, GTP-binding hetero-oligomers that polymerize to form a membrane-associated lattice. The contractile ring also contains a potential filament crosslinker, Anillin, that binds all three filament types. Here, we show that the contractile ring possesses an intrinsic symmetry-breaking mechanism that promotes asymmetric furrowing. Asymmetric ingression requires Anillin and the septins, which promote the coalescence of components on one side of the contractile ring, but is insensitive to a 10-fold reduction in myosin II levels. When asymmetry is disrupted, cytokinesis becomes sensitive to partial inhibition of contractility. Thus, asymmetric furrow ingression, a prevalent but previously unexplored feature of cell division in metazoans, is generated by the action of two conserved furrow components and serves a mechanical function that makes cytokinesis robust.
在胞质分裂过程中，皮层收缩环的收缩产生一个沟，将一个细胞分成两个。收缩环包含三种细丝系统：肌动蛋白、双极肌球蛋白II细丝和隔膜蛋白，后者是聚合形成膜相关晶格的GTP结合异源寡聚体。收缩环还包含一种潜在的细丝交联剂——膜收缩蛋白，它能结合所有三种细丝类型。在这里，我们表明收缩环具有一种内在的对称破坏机制，可促进不对称沟陷。不对称内陷需要膜收缩蛋白和隔膜蛋白，它们促进收缩环一侧成分的聚结，但对肌球蛋白II水平降低10倍不敏感。当不对称性被破坏时，胞质分裂对收缩性的部分抑制变得敏感。因此，不对称沟陷是后生动物细胞分裂中一个普遍但以前未被探索的特征，它由两种保守的沟成分的作用产生，并起到使胞质分裂稳健的机械功能。
