The regulation of transferrin receptor and glutathione peroxidase mRNAs synthesis by changes in intracellular iron levels.

The effect of changes of iron availability in the culture medium on the expression of TfR (transferrin receptor) and glutathione peroxidase (GSHPx) genes was investigated in uninduced or induced murine erythroleukemia (Friend) cells of lines 707 and Fw labeled with (3H)uridine for 3 h. The level of the labeled cytoplasmic TfR mRNA exhibited about 2-3-fold increase and the level of the labeled GSHPx mRNA about 2-fold increase in induced Friend 707 cells in comparison with uninduced cells. Raising the levels of intracellular iron by treatment of Friend 707 cells with either hemin, Fe-pyridoxal isonicotinoyl hydrazone (PIH) or diferric transferrin (Tf) resulted in decreased levels of the labeled TfR mRNA. On the other hand, hemin and Fe-PIH caused an increase in the labeled cytoplasmic GSHPx mRNA. Conversely, treatment with PIH or desferrioxamine stimulated synthesis of TfR mRNA and decreased the levels of the labeled GSHPx mRNA. In Fw cells we did not find any difference between the levels of the labeled cytoplasmic TfR mRNA in induced and uninduced cells and the levels of labeled cytoplasmic GSHPx mRNA were only slightly increased by induction. Changes of the intracellular iron pool caused the same effect as in Friend 707 cells.