DNA binding activity of C/EBPbeta and C/EBPdelta for the rat alpha2-macroglobulin gene promoter is regulated in an acute-phase dependent manner.
Turpentine-induced acute-phase (AP) response in rats is followed by transcriptional activation of the alpha2-macroglobulin (MG) gene mediated by cytokine interleukin-6 (IL-6) and glucocorticoids. Based on nucleotide sequence analysis of the alpha2-MG gene promoter regions responsive to IL-6, we postulated that binding of members of the liver-enriched CCAAT-enhancer-binding proteins (C/EBP) family of transcription factors to the type I IL-6 responsive element (IL-6RE) may participate in the transcriptional activation of this gene during AP response. Results of Western immunoblot and Northern-blot assays revealed coordinate changes in the pool levels of C/EBPalpha, -beta. and -delta protein isoforms and their genes expression in liver in response to turpentine. By means of an in vitro phosphorylation assay, South-Western blot, and selective proteolysis we have also found that only abilities of 35-kD C/EBPbeta and 27-kD C/EBPdelta to bind to the alpha2-MG gene promoter were affected by phosphorylation. Based on these data we concluded that transcriptional induction of the rat alpha2-MG gene during AP response correlates with both increased synthesis and phosphorylation-induced binding of 35-kD C/EBPbeta and 27-kD C/EBPdelta.
Milosavljevic
T S
TS
Department for Molecular Biology, Institute for Biological Research Sinisa Stankovic, Belgrade 11060, Serbia, Federal Republic of Yugoslavia. pemi@ibiss.bg.ac.yu
Petrovic
M V
MV
Cvetkovic
I D
ID
Grigorov
I I
II
D000210:Acute-Phase Reaction; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D051743:CCAAT-Enhancer-Binding Protein-delta; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D008099:Liver / Q000378:metabolism; D008110:Liver Extracts; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010766:Phosphorylation; D051381:Rats; D014157:Transcription Factors; D000511:alpha-Macroglobulins / Q000235:genetics*
D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C497254:Cebpd protein, rat; D008110:Liver Extracts; D014157:Transcription Factors; D000511:alpha-Macroglobulins; D051743:CCAAT-Enhancer-Binding Protein-delta; D004247:DNA