Localization of iron metabolism-related mRNAs in rat liver indicate that HFE is expressed predominantly in hepatocytes

The mRNAs of proteins involved in iron metabolism were measured in isolated hepatocytes, Kupffer cells, sinusoidal endothelial cells (SECs), and hepatic stellate cells (HSCs). Levels of type I hereditary hemochromatosis gene (HFE), transferrin, hepcidin, transferrin receptors 1 and 2 (TfR1, TfR2), ferroportin 1 (FPN1), divalent metal transporter 1 (DMT1), natural resistance-associated macrophage protein 1 (Nramp1), ceruloplasmin, hephaestin, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), were measured by quantitative reverse-transriptase polyerase chain reaction (qRT-PCR). We show that hepatocytes express almost all the iron-related genes tested, in keeping with their central role in iron metabolism. In addition, hepatocytes had 10-fold lower TfR1 mRNA levels than TfR2 and the lowest levels of TfR1 of the 4 cell types isolated. Kupffer cells, which process senescent red blood cells and recycle the iron, had high levels of ferroportin 1, ceruloplasmin, and hephaestin mRNA. Most important, of all the cell types tested, hepatocytes had the highest level of HFE mRNA, a factor of 10 higher than Kupffer cells. In situ hybridization analysis was conducted with rat liver sections. Consistent with the qRT-PCR analysis, HFE gene expression was localized mainly in hepatocytes. Western blot analysis confirmed this finding. Unexpectedly, HSCs also had high levels of DMT1 and ferroportin, implicating them in either iron sensing or iron cycling.