Enhancement of ligand-dependent down-regulation of glucocorticoid receptor by lipopolysaccharide

Noriyasu Hirasawa, Kazushi Yashima, Kenji Ishihara

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Aims: The inhibitory actions of glucocorticoids are often attenuated in inflamed tissues. The aim of the present study was to investigate whether the dexamethasone-induced downregulation of glucocorticoid receptor (GR) expression was enhanced by the stimulation with lipopolysaccharide (LPS). Main methods: Various cells were stimulated with LPS (1 μg/ml) for 30 min and then treated with dexamethasone (1 μM) for specified periods. The levels of GR and the phosphorylation at Ser211 were determined by Western blot. The effects of kinase inhibitors and a proteasome inhibitor on them were examined. Key findings: The treatment of NCI-H292 cells with dexamethasone reduced the levels of GR, and the pretreatment with LPS accelerated the reduction. Such an enhancement by LPS of the dexamethasone-induced downregulation was observed in the respiratory epithelial cell lines BEAS-2B and A549, but not in the keratinocyte-like cell line HaCaT, the hematopoietic cell lines U937, THP-1 and Eol-1, or in hepatocytoma HepG2 cells. The treatment with dexamethasone and LPS apparently decreased GR levels in the lungs of BALB/c mice but not in the liver. In NCI-H292 cells, the LPS-enhanced downregulation of GR expression was recovered by the proteasome inhibitor MG-132. SP600125, SB203580 and roscovitine but not U0126 inhibited the LPS-induced enhancement of both the phosphorylation and the downregulation of GR. Significance: These findings suggested that the ligand-dependent downregulation of GR expression via the proteasome was apparent in the respiratory epithelial cells and enhanced by lipopolysaccharide via the activation of p38 MAP kinase, c-Jun N-terminal kinase and cyclin-dependent kinases.

Original languageEnglish
Pages (from-to)578-585
Number of pages8
JournalLife Sciences
Volume85
Issue number15-16
DOIs
Publication statusPublished - 2009 Oct 7

Keywords

  • Dexamethasone
  • Epithelial cell
  • Glucocorticoid receptor
  • Lipopolysaccharide
  • Proteasome

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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