원문정보
초록
영어
Sialic acid, the terminal sugar in N-linked complex glycans, is usually found in glycoproteins and plays a major role in determining the circulatory lifespan of glycoproteins. In this study, we attempted to enhance the sialylation of recombinant erythropoietin (EPO) in Chinese hamster ovary (CHO) cells. To enhance EPO sialylation, we introduced human α2,3-sialyltransferase (α
2,3-ST) and CMP-sialic acid synthase (CMP-SAS) into recombinant human EPO-producing CHO cells. The sialylation of EPO was increased by the expression of α2,3-ST alone. Although the co-expression of α2,3-ST and CMP-SAS did not increase sialylation, an increase in the intracellular pool of CMP-sialic acid was noted. Based on these observations, it was postulated
that the transport capacity of CMP-sialic acid into the Golgi lumen was limited, thereby causing the reduced availability of CMP-sialic acid substrate for sialylation. Therefore, we co-expressed human α2,3-ST and CMP-SAS, as well as also over-expressed Chinese hamster CMP-sialic acid transporter (CMP-SAT) in CHO cells, which produced recombinant human EPO. When α
2,3-ST, CMP-SAS, and CMP-SAT were over-expressed in CHO cells, there was a corresponding increase in sialylation compared to the co-expression of α2,3-ST and CMP-SAS. The present study provides a useful strategy to enhance the sialylation of therapeutic glycoproteins produced in CHO cells.