Barkan R S, Kudriavtseva N V, Reshetnikova G F
Institute of Cytology, Russian Academy of Sciences, St. Petersburg.
Tsitologiia. 1998;40(2-3):172-7.
It has been confirmed that the main actin-dependent period of G1 phase of the cell cycle is the middle of G1. As the critical points in G1 phase are associated with the synthesis of cycling D and E and with the formation of their active complexes with cyclin-dependent kinases (Cdk's), a study of a possible influence of actin filaments on these processes was performed. The activity of G1 kinases was estimated by the degree of phosphorylation of their specific substrate-retinoblastoma protein (pRb). Immunoblot analysis with specific antibodies to pRb revealed hypophosphorylated from of Rb in lysates of resting Swiss 3T3 cells and the appearance of hyperphosphorylated form after 12 h of EGF and serum stimulation. In was shown that actin filaments distruction by H2CB led to a decrease in hyper phosphorylated form appearance, depending on the depth of resting state of the cells and efficiency of their stimulation by growth factors. Thus, these data may suggest the involvement of actin cytoskeleton in functioning of the transcription chain cyclin/Cdk-R1-E2F.
已经证实，细胞周期G1期主要的肌动蛋白依赖期是G1期的中期。由于G1期的关键点与细胞周期蛋白D和E的合成以及它们与细胞周期蛋白依赖性激酶（Cdk）形成活性复合物有关，因此开展了一项关于肌动蛋白丝对这些过程可能影响的研究。通过其特异性底物视网膜母细胞瘤蛋白（pRb）的磷酸化程度来评估G1激酶的活性。用针对pRb的特异性抗体进行免疫印迹分析，结果显示在静止的瑞士3T3细胞裂解物中Rb呈低磷酸化形式，在表皮生长因子（EGF）和血清刺激12小时后出现高磷酸化形式。结果表明，H2CB破坏肌动蛋白丝会导致高磷酸化形式的出现减少，这取决于细胞静止状态的深度及其受生长因子刺激的效率。因此，这些数据可能表明肌动蛋白细胞骨架参与了细胞周期蛋白/Cdk-R1-E2F转录链的功能。
