Differential hormone-dependent transcriptional activation and -repression by naturally occurring human glucocorticoid receptor variants.
The molecular mechanisms underlying primary glucocorticoid resistance or hypersensitivity are not well understood. Using transfected COS-1 cells as a model system, we studied gene regulation by naturally occurring mutants of the glucocorticoid receptor (GR) with single-point mutations in the regions encoding the ligand-binding domain or the N-terminal domain reflecting different phenotypic expression. We analyzed the capacity of these GR variants to regulate transcription from different promoters, either by binding directly to positive or negative glucocorticoid-response elements on the DNA or by interfering with protein-protein interactions. Decreased dexamethasone (DEX) binding to GR variants carrying mutations in the ligand-binding domain correlated well with decreased capacity to activate transcription from the mouse mammary tumor virus (MMTV) promoter. One variant, D641V, which suboptimally activated MMTV promoter-mediated transcription, repressed a PRL promoter element containing a negative glucocorticoid-response element with wild type activity. DEX-induced repression of transcription from elements of the intercellular adhesion molecule-1 promoter via nuclear factor-kappaB by the D641V variant was even more efficient compared with the wild type GR. We observed a general DEX-responsive AP-1-mediated transcriptional repression of the collagenase-1 promoter, even when receptor variants did not activate transcription from the MMTV promoter. Our findings indicate that different point mutations in the GR can affect separate pathways of gene regulation in a differential fashion, which can explain the various phenotypes observed.
de Lange
P
P
Department of Internal Medicine III, Erasmus University, Rotterdam, The Netherlands.
Koper
J W
JW
Huizenga
N A
NA
Brinkmann
A O
AO
de Jong
F H
FH
Karl
M
M
Chrousos
G P
GP
Lamberts
S W
SW
D000818:Animals; D019556:COS Cells / Q000378:metabolism; D017364:Collagenases / Q000235:genetics / Q000378:metabolism; D003907:Dexamethasone / Q000378:metabolism / Q000494:pharmacology; D014644:Genetic Variation; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D009154:Mutation; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011388:Prolactin / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011965:Receptors, Glucocorticoid / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D016328:NF-kappa B; D011965:Receptors, Glucocorticoid; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D018799:Intercellular Adhesion Molecule-1; D003907:Dexamethasone; D011388:Prolactin; D008156:Luciferases; D017364:Collagenases; D013755:Tetradecanoylphorbol Acetate