Exchange in binding of transcription factors C/EBPalpha and C/EBPbeta at a regulatory site in the alpha1-acid glycoprotein (AGP) promoter, termed the acute phase response element (APRE), has been correlated with bacterial lipopolysaccharide (LPS) mediated induction. The APRE contains overlapping recognition sequences for C/EBP's and glucocorticoid receptor (GR). Electrophortetic mobility shift assays show that this site can bind both GR and C/EBP. However, using liver nuclear extract, which contains GR binding activity, only C/EBP binds to the APRE. Binding interference methods, using dimethyl sulfate and potassium permanganate modification of specific bases, detected interference only with modification of bases that are in the region of the C/EBP binding site that do not overlap with the GRE sequence. There are no significant differences between the interference patterns of control and LPS treated liver nuclear extracts, suggesting that the region of close contact between protein and DNA is similar for C/EBPalpha (untreated) and C/EBPbeta (treated).
Copyright 1999 Academic Press.