DIFFERENTIAL AUTOREGULATION OF GLUCOCORTICOID RECEPTOR EXPRESSION IN HUMAN T-CELL AND B-CELL LINES
DIFFERENTIAL AUTOREGULATION OF GLUCOCORTICOID RECEPTOR EXPRESSION IN HUMAN T-CELL AND B-CELL LINES
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DOI：
10.1210/en.133.1.248
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发表时间：
1993-07-01
期刊：
影响因子：
4.8
通讯作者：
HARMON, JM
中科院分区：
文献类型：
--
作者：
DENTON, RR;EISEN, LP;HARMON, JM
在糖皮质激素敏感的人白血病T细胞系6TG1.1和人B细胞系IM-9中检查了糖皮质激素受体（GR）的同源配体对其表达的调节。与用1 μ M地塞米松处理16-18小时后在IM-9细胞中观察到的GR mRNA的减少相反，如通过北方印迹和RNA酶保护分析所确定的，处理6TG1.1细胞导致GR mRNA增加8倍，GR蛋白相应增加3- 4倍。在10-100 nM地塞米松之间观察到6TG1.1细胞中GR mRNA和蛋白的半数最大诱导，并且包含1 μ M RU 38486完全阻断100 nM地塞米松的作用，表明6TG1.1细胞中GR表达的正性自身调节是受体介导的应答。在糖皮质激素中也观察到GR表达的正性自身调节。耐药CEM-C1细胞，其含有功能性GR，但其生长不受糖皮质激素的影响。因此，积极的自我调节既不是生长停滞的结果，也不是生长停滞的唯一原因。在IM-9细胞中的负性自动调节和在6TG1.1细胞中的正性自动调节的程度不受用放线菌酮抑制蛋白质合成的影响。在6TG1.1细胞与放线菌素D治疗GR mRNA周转的测量显示，半衰期为2.5小时，这是不受地塞米松治疗。在IM-9细胞中测定了类似的半衰期，并且也不受类固醇治疗的影响。这些结果与糖皮质激素介导的GR表达的自动调节是组织特异性的初级转录反应的解释是一致的。
Regulation of glucocorticoid receptor (GR) expression by its cognate ligand was examined in the glucocorticoid-sensitive human leukemic T-cell line 6TG1.1 and in the human B-cell line IM-9. In contrast to the decrease in GR mRNA seen in IM-9 cells after treatment with 1 muM dexamethasone for 16-18 h, treatment of 6TG1.1 cells resulted in an 8-fold increase in GR mRNA, as determined by Northern blot and RNase protection analysis, with a corresponding 3- to 4-fold increase in GR protein. Half-maximal induction of GR mRNA and protein in 6TG1.1 cells was observed between 10-100 nM dexamethasone, and inclusion of 1 muM RU 38486 completely blocked the effects of 100 nM dexamethasone, demonstrating that positive autoregulation of GR expression in 6TG1.1 cells is a receptor-mediated response. Positive autoregulation of GR expression was also observed in glucocorticoid. resistant CEM-C1 cells, which contain functional GR, but whose growth is unaffected by glucocorticoids. Thus, positive autoregulation is neither a consequence nor the sole cause of growth arrest. The degree of negative autoregulation in IM-9 cells and positive autoregulation in 6TG1.1 cells was unaffected by inhibition of protein synthesis with cycloheximide. Measurement of GR mRNA turnover in 6TG1.1 cells treated with actinomycin-D revealed a half-life of 2.5 h, which was unaffected by dexamethasone treatment. A similar half-life was determined in IM-9 cells and was also unaffected by steroid treatment. These results are consistent with the interpretation that glucocorticoid-mediated autoregulation of GR expression is a tissue-specific primary transcriptional response.