Previous Article | Next Article ![]()
Mol. Cell. Biol., Feb 1995, 1005-1013, Vol 15, No. 2
W Liu, AG Hillmann and JM Harmon
The role of the ligand in glucocorticoid receptor-mediated transactivation
and transrepression of gene expression was investigated. Half-maximal
transactivation of a mouse mammary tumor virus-chloramphenicol
acetyltransferase reporter gene in transfected cells expressing the human
glucocorticoid receptor mutant GRL753F, from which the rate of ligand
dissociation is four to five times higher than the rate of dissociation
from normal receptors, required a 200- to 300- fold-higher concentration of
dexamethasone than was required in cells expressing the normal receptor.
Immunocytochemical analysis demonstrated that this difference was not the
result of a failure of the mutant receptor to accumulate in the nucleus
after steroid treatment. In contrast, in cells cotransfected with a
reporter gene containing the AP-1-inducible collagenase gene promoter, the
concentration of dexamethasone required for 50% transrepression was the
same for mutant and normal receptors. Efficient receptor-mediated
transrepression was also observed with the double mutant GRL753F/C421Y, in
which the first cysteine residue of the proximal zinc finger has been
replaced by tyrosine, indicating that neither retention of the ligand nor
direct binding of the receptor to DNA is required. RU38486 behaved as a
full agonist with respect to transrepression. In addition,
receptor-dependent transrepression, but not transactivation, was observed
in transfected cells after heat shock in the absence of the ligand. Taken
together, these results suggest that unlike transactivation,
transrepression of AP-1 activity by the nuclear glucocorticoid receptor is
ligand independent.
Copyright © 1995, American Society for Microbiology
Hormone-independent repression of AP-1-inducible collagenase promoter activity by glucocorticoid receptors
Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|