Distinct Features of Iron Metabolism in Erythroid Cells: Implications for Heme Synthesis Regulation
Except for mature erythrocytes, and perhaps other terminally differentiated cells, all animal cells have the ability to synthesize heme1. Virtually all eukaryotic cells require iron to maintain normal cellular metabolism, because iron is an essential component of ubiquitous heme proteins and also numerous non-heme iron-containing enzymes2,3. Heme plays a fundamental role in a multiplicity of crucial biochemical reactions and its synthesis is finely tuned to these requirements which vary greatly among various cells and tissues. As compared to other cells in the organism, rapid rates of heme biosynthesis occur in liver and erythroid cells where large amounts of heme are needed not only for mitochondrial cytochromes but also as prosthetic groups for cytochrome P450 and hemoglobin, respectively. Even between these two tissues there is a dramatic difference in synthetic rates since, on a per cell basis, erythroid cells produce heme several fold faster than hepatocytes. This is not unexpected since hemoglobin is the most abundant hemoprotein, containing as much as 70% of the total iron content of a normal adult. It is thus reasonable to expect that both iron metabolism and the regulation of heme synthesis are different in hemoglobin-synthesizing as compared to non-erythroid cells.
KeywordsIron Metabolism Transferrin Receptor Erythroid Cell Erythroid Differentiation Heme Biosynthesis
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