Inhibition of glucocorticoid receptor-mediated transcriptional activation by p38 mitogen-activated protein (MAP) kinase.
Tumor necrosis factor (TNF) promotes certain immune and inflammatory responses, whereas glucocorticoids exert immunosuppressive and anti-inflammatory actions. We show that TNF treatment produced a modest inhibition of glucocorticoid receptor (GR)-mediated transcriptional activation of a mouse mammary tumor virus (MMTV) promoter-driven luciferase construct in HeLa cells. The mitogen-activated protein (MAP) kinases, p38 and c-Jun N-terminal kinase (JNK), are important mediators of target gene activation by TNF, and JNK activation was earlier shown to inhibit GR-mediated transcriptional activation by direct phosphorylation of GR at Ser-246. Transfection of HeLa cells with MKK6b(E), a constitutively active specific upstream activator of p38, led to a potent inhibition of GR activation of the MMTV promoter-driven luciferase construct. A similar inhibition of activation of the MMTV promoter-driven luciferase construct was seen in HeLa cells transfected with MKK7(D), a constitutively functional activator of JNK. Data from "domain swap" experiments using GR chimeras indicated that the main target of the p38-mediated (but not JNK-mediated) inhibition is the ligand-binding domain of GR (spanning amino acids 525-795), whereas the constitutively active N-terminal AF-1 region (spanning amino acids 106-237) is dispensable for the inhibitory effect of p38. We also demonstrate that activated p38 targets the GR ligand-binding domain indirectly. Suppression of GR function by activated p38 and JNK MAP kinases may be physiologically important as a mechanism of resistance to glucocorticoids seen in many patients with chronic inflammatory conditions.
Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA.
Zoltán
Z
Szatmáry
Michael J
MJ
Garabedian
Jan
J
Vilcek
D003001:Cloning, Molecular; D003907:Dexamethasone / Q000494:pharmacology; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D048669:MAP Kinase Kinase 6 / Q000235:genetics / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D011965:Receptors, Glucocorticoid; D011994:Recombinant Proteins; D003907:Dexamethasone; D048051:p38 Mitogen-Activated Protein Kinases; D048669:MAP Kinase Kinase 6