Erythropoietin, Thrombopoietin and Leptin Receptors: Signal transduction pathways

International audienceErythropoietin (Epo), Thrombopoietin (Tpo) and leptin are hormones with distinct physiological properties. While the first two regulate survival, growth and differentiation of erythroid and megakaryocytic progenitors respectively, leptin is crucial for mammalian body weight regulation[1–3]. Receptors for these ligands have been isolated and well- characterized; they belong to the class I cytokine receptor family that includes most interleukin receptors involved in hematopoiesis as well as those for prolactin and growth hormone (see Chapter 7) which play an important role in metabolism and reproduction [4]. This family of receptors shares structural similarities both in their extracellular and intracellular domains and is characterized by the absence of an intrinsic tyrosine kinase. Nevertheless, ligand binding to this type of receptor induces the tyrosine phosphorylation of many cellular substrates including the receptor itself, leading to the activation of distinct signaling pathways. This review will focus first on the structure and biological properties of Epo, Tpo, leptin and their receptors. The second part will summarize the signal transduction pathways induced by these three ligands and their roles in cell proliferation, differentiation and survival