Lamb J, Wheatley D N
Department of Cell Pathology, University of Aberdeen, MacRobert Building, 581 King Street, Aberdeen, AB24 5UA, Scotland, United Kingdom.
Exp Cell Res. 2000 Mar 15;255(2):238-49. doi: 10.1006/excr.1999.4779.
Withdrawal of a single amino acid (arginine) from freely cycling early passage primary human fibroblasts caused a halt to proliferation, characterized by an accumulation of cells in the G1 phase of the cell cycle. This arrest was accompanied by the suppression of cyclin D1- and cyclin E-associated kinase activities and the appearance of hypophosphorylated retinoblastoma protein. Arginine-deprived cells remained viable for in excess of 4 days and could be made to synchronously reenter the cell cycle by restoration of the amino acid, with kinetics characteristic of exit from a quiescent state. Stimulation of cells arrested by serum withdrawal did not result in S-phase entry when arginine was omitted from the culture medium. Although cyclin D1 accumulated on normal schedule, cdk4, which increased following restimulation in amino acid-replete medium, was not induced when arginine was absent. These results suggest that arginine deprivation-in common with other "suboptimal" conditions-inhibits the passage of normal human cells through the restriction point and implicate cdk4 as the key regulatory element in amino acid-sensitive cell cycle control.
从处于自由循环状态的早期传代原代人成纤维细胞中去除单一氨基酸（精氨酸）会导致细胞增殖停止，其特征是细胞在细胞周期的G1期积累。这种停滞伴随着细胞周期蛋白D1和细胞周期蛋白E相关激酶活性的抑制以及低磷酸化视网膜母细胞瘤蛋白的出现。精氨酸剥夺的细胞存活超过4天，通过恢复氨基酸可使其同步重新进入细胞周期，其动力学具有从静止状态退出的特征。当从培养基中省略精氨酸时，刺激因血清剥夺而停滞的细胞不会导致进入S期。尽管细胞周期蛋白D1按正常时间表积累，但在富含氨基酸的培养基中重新刺激后增加的细胞周期蛋白依赖性激酶4（cdk4），在没有精氨酸时不会被诱导。这些结果表明，与其他“次优”条件一样，精氨酸剥夺会抑制正常人类细胞通过限制点，并暗示cdk4是氨基酸敏感细胞周期控制中的关键调节元件。
