[Analysis of the iron-related proteins during proliferation and differentiational change of human hepatoblastoma cells (HepG2)].
The modulation of cellular iron metabolism depends on the expression of ferritin and transferrin receptor (TfR). These proteins are regulated post-transcriptionally by interaction of specific sequences, termed iron responsive elements (IRE) which are located in the 5' untranslated region (UTR) of ferritin mRNA and 3'UTR of TfR mRNA and a specific cytosolic protein, termed iron responsive element-binding protein (IRE-BP). The liver plays an important role in iron metabolism as a major organ of iron storage. In hepatocytes iron is taken up in the form of transferrin and intercellular iron levels are regulated by IRE/IRE-BP interaction. In spite of the important role of IRE/IRE-BP interaction, the role of it for proliferation and differentiational change in hepatoma cells is not well known. In this study, the author has investigated IRE/IRE-BP interaction and its target protein expression during proliferation and differentiational change of human hepatoblastoma cells (HepG2). This study revealed that the binding activity of IRE-BP to IRE was increased when HepG2 cells were cultured with an iron-chelating agent, deferoxamine (4.5 microM), and it was decreased when cultured with transferrin (100 micrograms/ml) during both proliferation and differentiational change induced by sodium butyrate. Also, the change of TfR expression was correlated with that of IRE-BP. These findings suggest that IRE/IRE-BP interaction may play an important role in the expression of TfR and cellular iron metabolism during proliferation and differentiational change of HepG2 cells.
Kamiya
K
K
Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
D001483:Base Sequence; D002454:Cell Differentiation; D002455:Cell Division; D018197:Hepatoblastoma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D008969:Molecular Sequence Data; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D016601:RNA-Binding Proteins; D011990:Receptors, Transferrin