Mitochondrial regulation of erythropoiesis in homeostasis and disease.

Erythroid cells undergo a highly complex maturation process, resulting in dynamic changes that generate red blood cells (RBCs) highly rich in haemoglobin. The end stages of the erythroid cell maturation process primarily include chromatin condensation and nuclear polarization, followed by nuclear expulsion called enucleation and clearance of mitochondria and other organelles to finally generate mature RBCs. While healthy RBCs are devoid of mitochondria, recent evidence suggests that mitochondria are actively implicated in the processes of erythroid cell maturation, erythroblast enucleation and RBC production. However, the extent of mitochondrial participation that occurs during these ultimate steps is not completely understood. This is specifically important since abnormal RBC retention of mitochondria or mitochondrial DNA contributes to the pathophysiology of sickle cell and other disorders. Here we review some of the key findings so far that elucidate the importance of this process in various aspects of erythroid maturation and RBC production under homeostasis and disease conditions.