Selective modulation of the glucocorticoid receptor can distinguish between transrepression of NF-κB and AP-1

Cell Mol Life Sci. 2014 Jan;71(1):143-63. doi: 10.1007/s00018-013-1367-4. Epub 2013 Jun 20.

Abstract

Glucocorticoids (GCs) block inflammation via interference of the liganded glucocorticoid receptor (GR) with the activity of pro-inflammatory transcription factors NF-κB and AP-1, a mechanism known as transrepression. This mechanism is believed to involve the activity of GR monomers. Here, we explored how the GR monomer-favoring Compound A (CpdA) affects AP-1 activation and activity. Our results demonstrate that non-steroidal CpdA, unlike classic steroidal GCs, blocks NF-κB- but not AP-1-driven gene expression. CpdA rather sustains AP-1-driven gene expression, a result which could mechanistically be explained by the failure of CpdA to block upstream JNK kinase activation and concomitantly also phosphorylation of c-Jun. In concordance and in contrast to DEX, CpdA maintained the expression of the activated AP-1 target gene c-jun, as well as the production of the c-Jun protein. As for the underlying mechanism, GR is a necessary intermediate in the CpdA-mediated gene expression of AP-1-regulated genes, but seems to be superfluous to CpdA-mediated JNK phosphorylation prolongation. The latter phenomenon concurs with the inability of CpdA to stimulate DUSP1 gene expression. ChIP analysis demonstrates that DEX-activated GR, but not CpdA-activated GR, is recruited to AP-1-driven promoters. Furthermore, in mice we observed that CpdA instigates a strong enhancement of TNF-induced AP-1-driven gene expression. Finally, we demonstrate that this phenomenon coincides with an increased sensitivity towards TNF lethality, and implicate again a role for JNK2. In conclusion, our data support the hypothesis that a ligand-induced differential conformation of GR yields a different transcription factor cross-talk profile.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Dexamethasone / pharmacology
  • Dual Specificity Phosphatase 1 / genetics
  • Dual Specificity Phosphatase 1 / metabolism
  • Gene Expression / drug effects
  • Humans
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitogen-Activated Protein Kinase 9 / deficiency
  • Mitogen-Activated Protein Kinase 9 / genetics
  • Mitogen-Activated Protein Kinase 9 / metabolism
  • Mitogen-Activated Protein Kinases / metabolism
  • NF-kappa B / metabolism*
  • Phosphorylation / drug effects
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-jun / genetics
  • Proto-Oncogene Proteins c-jun / metabolism
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Receptors, Glucocorticoid / antagonists & inhibitors
  • Receptors, Glucocorticoid / genetics
  • Receptors, Glucocorticoid / metabolism*
  • Staurosporine / pharmacology
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism*
  • Transcriptional Activation / drug effects
  • Triazoles / pharmacology
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Interleukin-6
  • NF-kappa B
  • Proto-Oncogene Proteins c-jun
  • RNA, Small Interfering
  • Receptors, Glucocorticoid
  • Transcription Factor AP-1
  • Triazoles
  • Tumor Necrosis Factor-alpha
  • compound A (octyltriazole)
  • Dexamethasone
  • Mitogen-Activated Protein Kinase 9
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases
  • Dual Specificity Phosphatase 1
  • Dusp1 protein, mouse
  • Staurosporine