Thrombopoietin: The THPO gene provides instructions for making a protein called thrombopoietin that promotes the growth and division (proliferation) of cells.
The THPO gene provides instructions for making a protein called thrombopoietin that promotes the growth and division (proliferation) of cells. This protein attaches to (binds) and turns on (activates) the thrombopoietin receptor, which stimulates several signaling pathways that transmit chemical signals from outside the cell to the cell's nucleus. These pathways are important for controlling the production of blood cells.
Thrombopoietin is especially important for the proliferation of certain blood cells called megakaryocytes, which produce platelets, the cells involved in blood clotting. Research suggests that thrombopoietin signaling may also play a role in the renewal of hematopoietic stem cells, which are stem cells located within the bone marrow that have the potential to develop into red blood cells, white blood cells, and platelets.
Several mutations in the THPO gene have been found in people with essential thrombocythemia, a condition characterized by an increased number of platelets in the blood. Because platelets are the blood cells involved in blood clotting, abnormal clotting (thrombosis) is common in people with essential thrombocythemia.
THPO gene mutations are found in families with an inherited form of the condition called familial essential thrombocythemia. These mutations affect a region of the gene that usually blocks (inhibits) the production of the thrombopoietin protein (a process called translation). THPO gene mutations lead to increased translation of the protein. The excess protein can abnormally activate the thrombopoietin receptor and the signaling pathways, leading to overproduction of megakaryocytes and increased numbers of platelets. Excess platelets can cause thrombosis, which leads to many signs and symptoms of essential thrombocythemia.