Premium
Inhibition of NF‐κB Binding Correlates With Increased Nuclear Glucocorticoid Receptor Levels in Acute Alcohol‐Treated Human Monocytes
Author(s) -
Mandrekar Pranoti,
Bellerose Gary,
Szabo Gyongyi
Publication year - 2002
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.2002.tb02495.x
Subject(s) - transactivation , glucocorticoid receptor , electrophoretic mobility shift assay , nfkb1 , lipopolysaccharide , glucocorticoid , nf κb , microbiology and biotechnology , chemistry , receptor , nuclear receptor , monocyte , gene expression , proinflammatory cytokine , transcription factor , endocrinology , medicine , biology , signal transduction , inflammation , biochemistry , gene
Background Acute alcohol treatment blocks inflammatory cytokines via inhibition of NF‐κB in monocytes in the presence of ongoing IκBα degradation, suggesting regulation of NF‐κB activation downstream of IκBα degradation. DNA binding of NF‐κB has been suggested to be regulated by other nuclear regulatory factors, including the glucocorticoid receptor (GR). Here, we show for the first time that acute alcohol (25 mM) exposure modulates GR activation in monocytes. Methods Human peripheral blood monocytes were treated with lipopolysaccharide (LPS) in the presence or absence of alcohol (25 mM) for 1 hour. Nuclear GR levels were estimated by Western blotting and NFκB activation was studied in the same extracts by gel shift analysis (EMSA). Cells were stimulated with 1 μM of Dex to be used as positive control for GR activation. GR/GRE binding was also determined in nuclear extracts by EMSA. IκBα mRNA known to be induced by GR/GRE activation was studied in total RNA extracts by the SuperArray method (SuperArray Inc., Bethesda, MD). Results LPS is a potent inducer of GR nuclear translocation and GR binding to the glucocorticoid response element (GRE). Acute alcohol treatment both induced ( p < 0.05) and augmented ( p < 0.05) LPS‐stimulated GR nuclear levels. However, alcohol inhibits LPS‐induced (nonligand bound) GR/GRE binding activity in monocytes. This inhibition of GR transactivation by alcohol was further confirmed by decreased expression (40%) of a target gene, IκBα. Thus, alcohol treatment increases nonligand‐bound nuclear GR, but inhibits its transactivation function. Ligand‐induced GR/GRE binding was decreased in alcohol‐treated monocytes. Inhibition of ligand‐induced GR/GRE binding by alcohol exposure is likely due to cytoplasmic retention of the GR. Conclusions Our results show that acute alcohol exposure inhibits GR in monocytes by differently affecting ligand‐ and nonligand‐induced GR nuclear translocation. These data also suggest that acute alcohol regulates GR activation in monocytes concomitant to inhibition of NF‐κB activation.