Regulation of the human glucocorticoid receptor by long-term and chronic treatment with glucocorticoid.
HeLa S3 cells that contain endogenous glucocorticoid receptors (GR) were treated with dexamethasone (DEX) for periods of time ranging from 24 h to 2 weeks or chronically over a 2-year period. Regulation of GR protein and mRNA were examined by affinity labeling, Western blotting, and Northern blotting. Relatively short-term treatment of cells with DEX for 24 or 48 h revealed more profound down-regulation of GR protein than of GR mRNA. However, by 2 weeks of DEX treatment, the levels of both receptor protein and mRNA were both maximally down-regulated. Cells that had been chronically DEX treated (for up to 2 years) had no measurable GR protein or mRNA. The down-regulation of receptor protein and RNA that occurred after 2 weeks of DEX treatment is completely reversible upon DEX removal, whereas reversibility did not occur with cells that had been chronically treated with DEX. Furthermore, transfection of a glucocorticoid responsive reporter plasmid into these chronically DEX-treated cells demonstrated that these cells were no longer responsive to steroid treatment. However, cotransfection of a plasmid encoding the human GR into these chronically DEX-treated cells resulted in restored production of GR and responsiveness to hormone, indicating that the defect in these cells occurs only at the receptor level.
Silva
C M
CM
Department of Physiology, University of North Carolina at Chapel Hill, 27599.
Powell-Oliver
F E
FE
Jewell
C M
CM
Sar
M
M
Allgood
V E
VE
Cidlowski
J A
JA
D015152:Blotting, Northern; D015153:Blotting, Western; D003907:Dexamethasone / Q000494:pharmacology*; D015536:Down-Regulation; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D012333:RNA, Messenger / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000187:drug effects*; D013997:Time Factors; D014162:Transfection
D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone