Identification and characterization of CF kinase

细胞分裂是有丝分裂过程中所有必需的细胞成分分离到有丝分裂后的子细胞中。蛋白质磷酸化在有丝分裂控制中起关键作用，但细胞分裂的细胞分裂机制尚不清楚。我们报道了一种磷酸化III型中间丝蛋白，胶质纤维酸性蛋白（GFAP）的蛋白激酶活性，特别是在细胞动力学细胞的卵裂沟处。它被称为卵裂沟激酶（CF）。现在，我们获得了rho相关激酶（rho激酶）是CF激酶的候选物的证据；rho激酶在体外磷酸化GFAP的位点与体内被CF激酶磷酸化的位点相同。我们还通过将突变体gfap引入III型中间丝阴性细胞，分析了CF激酶/ rho激酶活性的功能。CF激酶/ rho激酶磷酸化位点的突变破坏了GFAP向有丝分裂后子细胞的分离。结果，在未分离的子细胞之间形成了异常长的细胞质桥状结构。这些结果表明，CF激酶/ rho激酶对于GFAP分离成子细胞至关重要，从而确保有效的细胞分离。

Cytokinesis is the mitotic precess in which all the essential cell components are segregated into postmitotic daughter cells It is suggested that protein phoshorylation plays pivotal roles in mitotic control, however the mechanisms for the cellular separation in cytokineses are not well characterized. We reported a protein kinase activity that phosphorylates a type III intermediate filament protein, glial fiberllary acidic protein (GFAP), specifically at the cleavage furrow of cytokinetic cells. It was termed cleavage furrow (CF) kinase. Now, we obtained evidence that Rho-associated Kinase (Rho-kinase) is a candidate for CF kinase ; Rho-kinase phosphorylated GFAP in vitro at the same sites that were phosphorylated by CF kinase in vivo. We also analyzed the functions of CF kinase/Rho-kinase activity by introducing mutant GFAPs into type III intermediate filament-negative cells. The mutation in CF kinase/Rho-kinase phosphorylation sites impaired GFAP segregation into postmitotic daughter cells. As a result, unusually long cytoplasmic bridge-like structure was formed between unseparated dughter cells. These results suggst that CF kinase/Rho-kinase is essential for the segragation of GFAP into daughter cells which in turn ensures efficient cellular separation.