Selenium (Se) is incorporated as the 21st
amino acid selenocysteine (Sec) into the growing
polypeptide chain of
proteins involved in redox gatekeeper functions. Erythropoiesis presents a particular problem to redox regulation as the presence of
iron,
heme, and unpaired
globin chains lead to high levels of
free radical-mediated oxidative stress, which are detrimental to erythroid development and can lead to
anemia. Under homeostatic conditions, bone marrow erythropoiesis produces sufficient erythrocytes to maintain homeostasis. In contrast, anemic stress induces an alternative pathway, stress erythropoiesis, which rapidly produces new erythrocytes at extramedullary sites, such as spleen, to alleviate
anemia. Previous studies suggest that dietary Se protects erythrocytes from such oxidative damage and the absence of
selenoproteins causes
hemolysis of erythrocytes due to oxidative stress. Furthermore, Se deficiency or lack of
selenoproteins severely impairs stress erythropoiesis exacerbating the
anemia in rodent models and human patients. Interestingly, erythroid progenitors develop in close proximity with macrophages in structures referred to as erythroblastic islands (
EBIs), where macrophage expression of
selenoproteins appears to be critical for the expression of
heme transporters to facilitate export of
heme from macrophage stores to the developing erythroid cells. Here we review the role of Se and
selenoproteins in the intrinsic development of erythroid cells in addition to their role in the development of the erythropoietic niche that supports the functional role of
EBIs in erythroid expansion and maturation in the spleen during recovery from
anemia.