Svec F
Arch Biochem Biophys. 1985 Jul;240(1):184-90. doi: 10.1016/0003-9861(85)90022-0.
In order to investigate the mechanism through which glucocorticoids downregulate the number of their own receptors in the AtT-20 cell, the effect of glucocorticoids on cell protein metabolism was studied. Glucocorticoids were found to inhibit cellular protein accumulation when included in long-term cultures. The concentrations of agonists that cause a mid-maximal effect are similar to those needed to half-saturate the glucocorticoid receptor, suggesting that the growth-inhibiting effect is receptor-mediated. Two-dimensional electrophoresis of cytosolic extracts of treated and control cells suggested that the effect reflected a general suppression of overall protein accumulation rather than a selective effect on certain classes. Comparison of the protein to DNA ratio of control and dexamethasone-treated cells showed that the latter have higher ratios suggesting that cell composition may be altered by agonists. However, time-course studies of this effect indicated that this is basically an expression of a glucocorticoid effect on cell growth rather than a selective effect on protein metabolism. It is concluded that glucocorticoids inhibit overall AtT-20 cell growth and that this, in turn, manifests itself as a decrease in the rate of protein accumulation. It is suggested that this change in protein metabolism may be a minor component in the mechanism through which glucocorticoids decrease AtT-20 cell ACTH secretion and glucocorticoid receptor number.
为了研究糖皮质激素下调AtT - 20细胞中其自身受体数量的机制，对糖皮质激素对细胞蛋白质代谢的影响进行了研究。发现在长期培养中加入糖皮质激素会抑制细胞蛋白质积累。产生中等最大效应的激动剂浓度与使糖皮质激素受体半饱和所需的浓度相似，这表明生长抑制效应是由受体介导的。对处理过的细胞和对照细胞的胞质提取物进行二维电泳表明，这种效应反映了对总体蛋白质积累的普遍抑制，而不是对某些类别的选择性作用。对照细胞和地塞米松处理细胞的蛋白质与DNA比率比较显示，后者的比率更高，这表明激动剂可能会改变细胞组成。然而，对这种效应的时间进程研究表明，这基本上是糖皮质激素对细胞生长的效应表达，而不是对蛋白质代谢的选择性作用。得出的结论是，糖皮质激素抑制AtT - 20细胞的总体生长，而这反过来又表现为蛋白质积累速率的降低。有人提出，蛋白质代谢的这种变化可能是糖皮质激素降低AtT - 20细胞促肾上腺皮质激素分泌和糖皮质激素受体数量机制中的一个次要成分。
