Construction of a fusion protein between N-terminal 153 peptide of thrombopoietin and erythropoietin

Thrombopoietin (TPO) functions as a regulator of megakaryocytes in their differentiation and maturation, and is a candidate pharmaceutical for the curing of thrombocytopenia. Erythropoietin (EPO) is a hematopoietic cytokine that regulates the level of red blood cell. It is widely used in renal anemia and tumor associated anemia, and is proved to be safe and effective. In order to study the possibility of using TPO EPO fusion protein for the curing of anemia and thrombocytopenia induced by high dose chemotherapy, a fusion gene is constructed by linking TPO N terminal 153 peptide and EPO mature peptide coding region. The fusion gene is expressed in mammalian cells, revealing that the expression product can support the growth of TPO responsive Ba/F3 mpl cells and EPO dependent Bet 2 cells in the absence of any other stimulating cytokine. It also stimulates the formation of erythroid colonies and megakaryocytic colonies in semi solid bone marrow cultures. These results indicate that the fusion protein has both the in vitro activities of TPO and EPO. The preliminary in vivo experiment reveals that the TPO EPO fusion protein containing cell supernatant raises the platelet level by 37% in mice, while its function on erythroid hematopoiesis remains to be determined. These results indicate that the construction of TPO EPO fusion protein and the further study of its use in high dose chemotherapy are possible