CONSTRUCTION OF A FUSION PROTEIN BETWEEN N-TERMINAL-153 PEPTIDE OF THROMBOPOIETIN AND ERYTHROPOIETIN

Thrombopoietin (TPO) functions as a regulator of megakaryocytes in the ir differentiation and maturation, and is a candidate pharmaceutical f or the curing of thrombocytopenia. Erythropoietin (EPO) is a hematopoi etic 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-EP O fusion protein for the curing of anemia and thrombocytopenia induced by high dose chemotherapy, a fusion gene is constructed by linking TP O N-terminal 153 peptide and EPO mature peptide-coding region. The fus ion gene is expressed in mammalian cells, revealing that the expressio n 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 cyt okine. It also stimulates the formation of erythroid colonies and mega karyocytic colonies in semi-solid bone marrow cultures. These results indicate that the fusion protein has both the in vitro activities of T PO and EPO. The preliminary in vivo experiment reveals that the TPO-EP O fusion protein containing cell supernatant raises the platelet level by 37 % in mice, while its function on erythroid hematopoiesis remain s to be determined. These results indicate that the construction of TP O-EPO fusion protein and the further study of its use in high dose che motherapy are possible.