Multiple mechanisms of iron-induced ferritin synthesis in HeLa cells.

Iron administration to HeLa cells stimulates the accumulation of H-subunit and L-subunit rich isoferritins at similar extent. The increase in both types of isoferritins is accompanied by an increase in the amount of messenger RNAs specific for H and L subunits. The increase in the amount of these messenger RNAs, which occurs in the nucleus as well as in the cytoplasm, is proportionately lower than the increase in the protein. These results, together with analysis of transcription in isolated nuclei indicate the existence of a mechanism of transcriptional control of ferritin synthesis, associated to the translational control described so far.