KLF15 is an important regulator of hepcidin gene transcription in hepatocytes. (A) AML-12 cells were transiently transfected with Klf15 and the indicated reporter gene for 36 hr and then treated with FSK for 12 hr. (B) AML-12 cells were co-transfected with wild-type (wt) and mutant (mt) forms of the Hamp gene promoter and Klf15 for 36 hr. After transfection, cells were treated with FSK for 12 hr. (C) Chromatin immunoprecipitation (ChIP) assay for the recruitment of KLF15 on the Hamp gene promoter. Mouse primary hepatocytes were infected with Ad-Scram and Ad-shKlf15 for 36 hr and then treated with FSK for 12 hr. Cell lysates were immunoprecipitated with an anti-KLF15 antibody. Purified DNA samples were employed for PCR using specific primers binding to specific proximal (Pro) and nonspecific distal (Dis) regions on the Hamp gene promoter. Input was 10% of soluble chromatin. (D) A schematic model illustrating the regulation of hepcidin gene expression and production. Fasting state and forskolin treatment can enhance hepatic hepcidin gene expression by stimulating the CRBN-KLF15 signaling network, which subsequently controls iron metabolism via an increase of hepcidin output and a decrease of iron production. *P < 0.05 vs. untreated control.