Thrombopoietin and its receptor: structure, function and role in the regulation of platelet production

Although thrombopoietin (Tpo) was already described in the early sixties, i t took more than 30 years before it was cloned. It became possible after th e recognition and cloning of its receptor, Mpl. In the past few years new i nformation about Tpo and Mpl has accumulated rapidly. Structure, biosynthes is and tissue expression have been elucidated. The central role of Tpo in t he regulation of megakaryocytopoiesis and platelet production has become cl ear, as has the way in which this is accomplished. Tpo appears to be an imp ortant growth factor for haematopoietic stem cells as well. Thus, it may be come one of the most important factors in stem cell transplantation. Finall y, the signal transduction mechanisms involved and the way in which Tpo aff ects platelets and their precursors functionally have been studied in detai l. The cloning and characterization of thrombopoietin and its receptor Mpl is one of the most important advances in the haematology of the nineties.