Lower ferroportin levels but higher ferroportin activity in PCBP1^ΔIEC mice. (A) Lower levels of ferroportin on duodenal epithelium of PCBP1^ΔIEC vs WT mice. Fluorescent immunohistochemistry for FPN in proximal duodenum from 2 months old mice. DAPI (4′,6-diamidino-2-phenylindole) stain indicates nuclei. Representative images on the left show quantitative analysis of fluorescence at right. (B) Lower levels of ferroportin in IECs of PCBP1^ΔIEC vs WT mice. IECs from 2 months mice analyzed for FPN and DMT1 by immunoblot. Representative blot on the left, quantitation on the right. (C) Intact tight junctions in intestinal epithelium of PCBP1^ΔIEC mice. Mice were administered FITC-dextran (4000 MW) through oral gavage. IECs and plasma were collected after 1 hour and FITC-dextran measured. (D) Higher levels of hepcidin mRNA in livers of PCBP1^ΔIEC vs WT mice. Hepcidin mRNA levels in liver were measured by qPCR in 2 months mice. (E) Higher levels of hepcidin mRNA in livers of PCBP1^ΔIEC mice on a high-iron diet. Mice were fed defined-iron diets for 1 month and liver hepcidin mRNA levels were analyzed. (F) Ferroportin mediates excess iron absorption through intestinal epithelium of PCBP1^ΔIEC mice. Mice were injected intraperitoneally with synthetic hepcidin or vehicle followed by oral gavage with ⁵⁷Fe solution. IECs, plasma, and liver samples were collected after 1 hour and ⁵⁷Fe levels measured.