Hematopoiesis is a dynamic process resulting in continuous production of
mature blood cells, from a small population of pluripotent stem cells through several
proliferative and differentiative events. Different functions of hematopoietic cells are
regulated by growth factors and cytokines, and by the interaction with other cells and
extracellular matrix.
Erythropoiesis is mainly orchestrated by erythropoietin and its receptor. Binding of this
growth factor to its receptor induces the activation of signal transduction intermediates,
especially the JAK2/STAT5 (Janus associated kinase 2/signal transducers and activators of
transcription 5), the mitogen activated protein (MAP) kinase and the phosphatidylinositol 3
(PI3) kinase pathways. Several transcription factors are then activated, which will initiate
transcription of specific genes. Embryonic and adult erythropoiesis require broad spectrum
transcription factors, as well as, specific erythroid transcription factors, which are necessary
for the regulation of cell cycle, cell survival, differentiation, proliferation and for the
intermediary metabolism of cells and to block apoptosis.
Keywords: Growth factors, growth factors receptors, signal transduction,
transcription factors.