Figure 6.

IL-1β-induced C/EBPδ is responsible for hepcidin induction. A–D, HepG2 cells were transfected with siRNA targeting the indicated gene. At 48 h after transfection, cells were treated with IL-1β (25 ng/ml) (A and B), or BMP2 (100 ng/ml) or IL-6 (10 ng/ml) or both (C and D) for 12 (A and B) or 4 h (C and D). Expression of C/EBPδ (A and C) or hepcidin (B and D) was examined by RT-qPCR analysis. The expression level in cells transfected with siGFP and treated without ligand was set at 1. The data are presented as the mean ± S.E. (n = 3). *, p < 0.05 and **, p < 0.01 versus cells transfected with the respective siRNA without ligand treatment. † and ††, p < 0.05 and p < 0.01 versus cells with corresponding ligand treatments and transfected with siGFP. F, HepG2 cells were treated with or without IL-1β (10 ng/ml) for 4 h. The cell lysates were incubated with biotinylated oligonucleotide probe targeting the putative C/EBP-BS, and the presence of C/EBPδ in the DNA-protein complexes was examined by Western blot analysis.