Pro-inflammatory cytokine induction of 11β-hydroxysteroid dehydrogenase type 1 in A549 cells requires phosphorylation of C/EBPβ at Thr235

PLoS One. 2013 Sep 26;8(9):e75874. doi: 10.1371/journal.pone.0075874. eCollection 2013.

Abstract

11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) converts inert glucocorticoids into active forms, thereby increasing intracellular glucocorticoid levels, important to restrain acute inflammation. 11β-HSD1 is induced by pro-inflammatory cytokines in a variety of cells. Here, we show 11β-HSD1 expression in human A549 epithelial cells is increased by pro-inflammatory cytokines (IL-1α/TNFα) via the P2 promoter of the HSD11B1 gene. Inhibition of p38 MAPK attenuated the pro-inflammatory cytokine induction of mRNA encoding 11β-HSD1 as well as that encoding C/EBPβ. IL-1α/TNFα-induced phosphorylation of C/EBPβ at Thr235 was also attenuated by p38 MAPK inhibition suggesting involvement of a p38 MAPK-C/EBPβ pathway. siRNA-mediated knock-down of C/EBPβ and NF-κB/RelA implicated both transcription factors in the IL-1α/TNFα induction of HSD11B1 mRNA. Transient transfections of HSD11B1 promoter-reporter constructs identified the proximal region of the P2 promoter of HSD11B1 as essential for this induction. IL-1α increased binding of C/EBPβ to the HSD11B1 P2 promoter, but this was not observed for NF-κB/RelA, suggesting indirect regulation by NF-κB/RelA. Ectopic expression of mutant chicken C/EBPβ constructs unable to undergo phosphorylation at the threonine equivalent to Thr235 attenuated the IL-1α-induction of HSD11B1, whereas mimicking constitutive phosphorylation of Thr235 (by mutation to aspartate) increased basal expression of HSD11B1 mRNA without affecting IL-1α-induced levels. These data clearly demonstrate a role for both C/EBPβ and NF-κB/RelA in the pro-inflammatory cytokine induction of HSD11B1 in human epithelial cells and show that p38 MAPK-induced phosphorylation of C/EBPβ at Thr235 is critical in this.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 11-beta-Hydroxysteroid Dehydrogenase Type 1 / genetics
  • 11-beta-Hydroxysteroid Dehydrogenases / metabolism*
  • Animals
  • CCAAT-Enhancer-Binding Protein-beta
  • CCAAT-Enhancer-Binding Proteins / metabolism*
  • Cell Line, Tumor
  • Chickens
  • Cytokines / metabolism*
  • Gene Expression Regulation / immunology*
  • Glucocorticoids / metabolism
  • Humans
  • Ligases / metabolism
  • NF-kappa B / metabolism
  • Phosphorylation
  • Promoter Regions, Genetic / genetics

Substances

  • CCAAT-Enhancer-Binding Protein-beta
  • CCAAT-Enhancer-Binding Proteins
  • CEBPB protein, human
  • Cytokines
  • Glucocorticoids
  • NF-kappa B
  • 11-beta-Hydroxysteroid Dehydrogenase Type 1
  • 11-beta-Hydroxysteroid Dehydrogenases
  • HSD11B1 protein, human
  • Ligases
  • guanosine 3',5'-polyphosphate synthetases