LPS increases binding of nuclear proteins to SRE3, SRE4, and SRE5 in the Egr-1 promoter.

(A) Nuclear extracts were prepared from THP-1 cells stimulated with LPS for 0 to 30 minutes. An inducible complex was observed in EMSAs using radiolabeled oligonucleotides spanning SRE3, SRE4, and SRE5. (B) Nuclear extracts from unstimulated THP-1 cells were incubated with radiolabeled oligonucleotides containing SRE4 or an Sp1 site. A 50 × excess of unlabeled oligonucleotide was used as a competitor. (C) Nuclear extracts were prepared from THP-1 cells with or without LPS (10 μg/mL) for 30 minutes. Nuclear extracts from unstimulated (upper panel) or LPS-stimulated (lower panel) cells were incubated with SRE4. Supershift experiments were performed with antibodies against SRF, Elk-1, and p65.