The hereditary hemochromatosis protein, HFE, inhibits iron uptake via downregulation of Zip14 in HEPG2 cells

Gao J, Zhao N, Knutson MD, Enns CA
Source: J Biol Chem
Publication Date: (2008)
Issue: 283(31): 21462-8
Research Area:
Cancer Research/Cell Biology
Cells used in publication:
Hep G2
Species: human
Tissue Origin: liver
Nucleofectorâ„¢ I/II/2b
Lack of functional hereditary hemochromatosis protein, HFE, causes iron overload predominantly in hepatocytes, the major site of HFE expression in the liver. In this study, we investigated the role of HFE on the regulation of both transferrin-bound iron (TBI) and non-transferrin-bound iron (NTBI) uptake in HepG2 cells, a human hepatoma cell line. Expression of HFE decreased both TBI and NTBI uptake. It also resulted in a decrease in the protein levels of Zip14 with no evident change in the mRNA level of Zip14. Zip14 (Slc39a14) is a metal transporter that mediates NTBI into cells (Liuzzi, JP et al. Proc. Natl. Acad. Sci. U. S. A. 2006 103:13612-7). Knockdown of Zip14 with siRNA abolished the effect of HFE on NTBI uptake. To determine if HFE had a similar effect on Zip14 in another cell line, HeLa cells expressing HFE under the tet-repressible promoter were transfected with Zip14. As in HepG2 cells, HFE expression inhibited NTBI uptake by ~50% and decreased Zip14 protein levels. Further analysis of protein turnover indicated that the half-life of Zip14 is lower in cells that express HFE. These results suggest that HFE decreases the stability of Zip14 and therefore reduces the iron loading in HepG2 cells.