Actinomycin D and the Regulation of Apoferritin Synthesis in Rat Liver

Abstract

IRON administration increases the net synthesis of apoferritin in rat liver in vivo¹. Correspondingly, liver slices prepared from rats dosed with iron incorporate ¹⁴C-leucine into apoferritin in vitro more readily than do slices from untreated controls². The mechanism by which the iron acts is unknown, although it has been postulated that intracellular iron in erythroblasts may influence genetic loci³. In the following experiments actinomycin D, an inhibitor of DNA-dependent RNA synthesis⁴, was administered to rats prior to a dose of iron, and liver slices were later tested in vitro for incorporation of ¹⁴C-leucine into apoferritin. Actinomycin D inhibited the stimulatory effect of iron, indicating that derepression of genes and the synthesis of messenger RNA are involved in the regulatory response to the metal.