Differential autoregulation of glucocorticoid receptor expression in human T- and B-cell lines

Endocrinology. 1993 Jul;133(1):248-56. doi: 10.1210/endo.133.1.8319574.

Abstract

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 microM 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 microM 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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • B-Lymphocytes / metabolism*
  • Blotting, Northern
  • Dactinomycin / pharmacology
  • Dexamethasone / pharmacology
  • Gene Expression Regulation* / drug effects
  • Humans
  • RNA Probes
  • RNA, Messenger / metabolism
  • Receptors, Glucocorticoid / genetics*
  • Ribonucleases
  • T-Lymphocytes / metabolism*

Substances

  • RNA Probes
  • RNA, Messenger
  • Receptors, Glucocorticoid
  • Dactinomycin
  • Dexamethasone
  • Ribonucleases