Reid S, Snow E C
Department of Microbiology and Immunology, University of Kentucky Medical Center, Lexington 40536-0084, U.S.A.
Mol Immunol. 1996 Oct;33(14):1139-51. doi: 10.1016/s0161-5890(96)00065-x.
Resting B-cells lack both cyclins D and E while constitutively expressing low levels of cdk4 and cdk2. B-cells receiving a complete growth stimulus express cyclin D2 by 10hr and cyclin E by 10-24hr poststimulation while increasing their protein levels of cdk4 and cdk2. B-cells receiving partial growth stimuli move into G1 without passing the G1 restriction point and transiently increase cyclin D2 mRNA levels without accumulating cyclin D2 protein. In the absence of cyclin D2 accumulation, cdk4 is not activated, and cyclin E is not expressed. These results suggest that signals responsible for moving B-cells through the G1 restriction point impact at the level of cyclin D2 protein accumulation. The possible implications of these results are discussed.
静止的B细胞既缺乏细胞周期蛋白D也缺乏细胞周期蛋白E，同时组成性地表达低水平的细胞周期蛋白依赖性激酶4（cdk4）和细胞周期蛋白依赖性激酶2（cdk2）。受到完全生长刺激的B细胞在刺激后10小时表达细胞周期蛋白D2，在10 - 24小时表达细胞周期蛋白E，同时其cdk4和cdk2的蛋白水平增加。受到部分生长刺激的B细胞进入G1期但未通过G1限制点，并且细胞周期蛋白D2的mRNA水平短暂增加，但细胞周期蛋白D2蛋白未积累。在没有细胞周期蛋白D2积累的情况下，cdk4未被激活，细胞周期蛋白E也未表达。这些结果表明，负责使B细胞通过G1限制点的信号在细胞周期蛋白D2蛋白积累水平上起作用。讨论了这些结果可能的意义。
