Thrombopoietin
- OMIM: 600044
- UniProt: P40225
Thrombopoietin or a thrombopoietin (gene name: THPO ) is a hormone that the formation and differentiation of platelet -forming cells, the megakaryocytes stimulated. It is within the scope of thrombopoiesis necessary for the production of blood platelets (thrombocytes).
Education center and properties
Thrombopoietin is formed in the liver, kidney, and in the bone marrow stromal cells. It takes at various points influence the course of hematopoiesis and acts as a cytokine. In addition to the effect on megakaryocytes and the resultant formation of platelet thrombopoietin acts on hematopoietic stem cells.
Structure and genetics
Thrombopoietin is an approximately 78 kDa glycoprotein. It consists of 332-335 amino acids. A part of protein ( N-terminal domain ) has a great similarity to erythropoietin, for the preparation of the erythrocytes (red blood cells) required hormone. The gene for thrombopoietin is located on the long arm of chromosome 3 ( q26.3 -27).
Regulation
The hormonal control loop of the thrombopoietin differs from that of most other hormones, because it is controlled by the number of available receptors. By the formation of thrombopoietin, platelet formation is promoted. These are able to bind to the circulating hormone in the blood by a thrombopoietin receptor disposed on its surface. In this way there is less thrombopoietin ready for formation of platelets.
Diagnosis and medical application
The thrombopoietin levels in the blood is used as a diagnostic detection. Thus, to correlate inversely proportional to the amount of platelets and megakaryocytes. At high platelet counts can therefore be observed a lower thrombopoietin levels. This in turn is reflected in a lower proportion of newly formed megakaryocytes. Inflammation, infection, liver failure or haematological disorders, however, can lead to unexpectedly high or low thrombopoietin levels.
In order to stimulate the formation with a congenital or chemotherapy -induced thrombocytopenia platelets lack of this, thrombopoietin as a drug of importance could be. Biotechnology, ie recombinant thrombopoietin is the subject of clinical research has shown to date, however, no significant effects. More promising are TPO receptor agonists, which are already being tested clinically.
Further Reading
- Warren S. Alexander and Craig Hyland: thrombopoietin bioassay. In: J. M. Gibbins and M. P. Mahaut -Smith ( eds ): Platelets and megakaryocytes: Volume 1: Functional Assays (Methods in Molecular Biology ) 1st edition, Humana Press, Totowa, 2004, ISBN 1588291014 pp. 347ff. .