Regulation of glucocorticoid receptors by glucocorticoids in cultured HeLa S3 cells.
Regulation of glucocorticoid receptors by glucocorticoids in cultured HeLa S3 cells.
复制标题
培养的 HeLa S3 细胞中糖皮质激素对糖皮质激素受体的调节。
作者：
N. B. Cidlowski;J. Cidlowski
HeLa S3 细胞含有糖皮质激素特异性的高亲和力、可饱和受体（相当于每个细胞 20,000 个）。 HeLa S3 细胞在含有地塞米松 (10(-6) M) 的培养基中生长，导致细胞核或细胞质地塞米松受体数量的总细胞水平显着降低（相当于 70%），而类固醇受体解离常数（Kd 相当于 1 X 10(-9) M）没有任何改变。受体数量的减少并不是简单的受体占据的结果，因为当直接添加[3H]地塞米松来调节受体数量时也会发生这种效应。对照细胞和地塞米松处理的细胞在0℃下120分钟和37℃下60分钟都达到受体结合的平衡状态，从而能够通过饱和曲线的Scatchard分析来估计受体数量和亲和力。当类固醇浓度低至 10(-9) M 时，糖皮质激素受体就会下调（减少 40%）。受体的这种变化发生在激素 24 小时后，但在 2 小时或 6 小时后不会发生。只有活性糖皮质激素（地塞米松、皮质醇）才能下调糖皮质激素受体。皮质醇、雌二醇和5α-二氢睾酮对此过程没有明显影响，而黄体酮(10(-7)M)则部分有效。亚细胞分布研究表明，糖皮质激素仅影响能够在 37°C 进行核转位的受体群体。我们的结论是，糖皮质激素可以通过未定义的机制调节其自身受体的代谢。
HeLa S3 cells contain high affinity, saturable receptors specific for glucocorticoids (congruent to 20,000 per cell). Growth of HeLa S3 cells in media containing dexamethasone (10(-6) M) results in a pronounced (congruent to 70%) reduction in the total cellular level of nuclear or cytoplasmic dexamethasone receptor number without any alteration in steroid-receptor dissociation constant (Kd congruent to 1 X 10(-9) M). This reduction in receptor number is not the result of simple receptor occupation, since this effect also occurs when receptor number is modulated by the direct addition of [3H]dexamethasone. Both control and dexamethasone-treated cells attain equilibrium states of receptor binding by 120 min at 0 C and by 60 min at 37 C, enabling estimation of receptor number and affinity by Scatchard analysis of saturation curves. Down-regulation of glucocorticoid receptor occurs at steroid concentrations as low as 10(-9) M (40% reduction). This alteration in receptor occurs after 24 h of hormone but not after either 2 or 6 h. Only the active glucocorticoids, (dexamethasone, cortisol) down-regulate glucocorticoid receptors. Cortexolone, estradiol, and 5 alpha-dihydrotestosterone have no apparent effect on this process, whereas progesterone (10(-7) M) is partially effective. Subcellular distribution studies indicate that glucocorticoids affect only that population of receptors capable of nuclear translocation at 37 C. We conclude that glucocorticoids can regulate the metabolism of their own receptors, via undefined mechanisms.