Glucocorticoids Antagonize AP-1 by Inhibiting the Activation/Phosphorylation of JNK without Affecting Its Subcellular Distribution

• Published in: The Journal of cell biology 2000-09, Vol.150 (5), p.1199-1207
• Main Authors: González, María Victoria, Jiménez, Benilde, Berciano, María T., González-Sancho, José Manuel, Caelles, Carme, Lafarga, Miguel, Muñoz, Alberto
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Cell Fractionation; Cell interaction; Cell nucleus; Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cells; Cellular biology; COS Cells; Cytosol; Cytosol - drug effects; Cytosol - metabolism; Dexamethasone - pharmacology; Enzyme Activation; Glucocorticoid receptors; Glucocorticoides; Glucocorticoids; Glucocorticoids - pharmacology; HeLa Cells; Humans; Interacció cel·lular; JNK Mitogen-Activated Protein Kinases; Kinetics; Mitogen-Activated Protein Kinases - drug effects; Mitogen-Activated Protein Kinases - metabolism; Phosphorylation; Proteins; Quantification; Recombinant Proteins - metabolism; Signal Transduction - drug effects; Transcription Factor AP-1 - antagonists & inhibitors; Transcription Factor AP-1 - metabolism; Transfection; Tumor Necrosis Factor-alpha - pharmacology; Tumors
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.150.5.1199

The immunosuppressive and antiinflammatory actions of glucocorticoid hormones are mediated by their transrepression of activating protein-1 (AP-1) and nuclear factor-kappa B (NFκB) transcription factors. Inhibition of the c-Jun NH2-terminal kinase (JNK) signaling pathway, the main mediator of AP-1 activation, has been described in extracts of hormone-treated cells. Here, we show by confocal laser microscopy, enzymatic assays, and immunoblotting that the synthetic glucocorticoid dexamethasone inhibited tumor necrosis factor α (TNF-α)-induced phosphorylation and activation of JNK in the cytoplasm and nucleus of intact HeLa cells. As a result, c-Jun NH2-terminal domain phosphorylation and induction were impaired. Dexamethasone did not block the TNF-α-induced JNK nuclear translocation, but rather induced, per se, nuclear accumulation of the enzyme. Consistently with previous findings, a glucocorticoid receptor mutant (GRdim), which is deficient in dimerization, DNA binding, and transactivation, but retains AP-1 transrepressing activity, was as efficient as wild-type GR in mediating the same effects of dexamethasone on JNK in transfected Cos-7 cells. Our results show that glucocorticoids antagonize the TNF-α-induced activation of AP-1 by causing the accumulation of inactive JNK without affecting its subcellular distribution.