The effect of iron on the synthesis and amount of ferritin in red blood cells during ontogeny.

Abstract

mammals. When excess iron was injected, mature red cells of larvae accumulated ferritin iron (increased from 200 pg/ml of cells to 410 pg/ml of cells) and ferritin protein (increased from 0.37 to 1.2% of the soluble protein), which resulted from the de novo synthesis of subunits (increased from 1.9 to 6.3% of the total protein synthesized); there was no detectable ferritin subunit pool. Iron did not change ferritin microheterogeneity. Ferritin synthesis was more sensitive (2-5 times) to inhibitors of translation than total protein syfithesis, indicating that iron may affect the translation of ferritin mRNA as previously observed in rat liver. In vitro, either transferrin or iron-nitrilotriacetic acid donated iron to red cells and ferritin; maximum uptake occurred with a combination of both donors. Iron storage in the larval red cell was similar to liver, except for the apparent absence of a ferritin subunit pool in red cells. Moreover, red cells were more efficient than the liver in acquiring iron for storage, and earlier studies showed that red cell iron stores were used more rapidly than liver stores;, the accessibility of red cells for iron storage may relate to their role in ontogeny. Although an ontogenetic decrease in available iron (transferrin) occurs which could affect red cell iron storage, increasing available iron experimentally had no effect on mature red cells of adults, suggesting an ontogenetic change at the cellular level independent of the change in transferrin.