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KMID : 0545120080180121945
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Journal of Microbiology and Biotechnology
2008 Volume.18 No. 12 p.1945 ~ p.1952
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Enhanced Sialylation of Recombinant Erythropoietin in CHO Cells by Human Glycosyltransferase Expression
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Jeong Yeon-Tae
Choi One
Lim Hye-Rim
Son Young-Dok
Kim Hong-Jin
Kim Jung-Hoe
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Abstract
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Sialylation, the attachment of sialic acid residues to a protein, can affect the biological activity and in vivo circulatory half-life of glycoproteins. Human α2,3- sialyltransferase (α2,3-ST) and β1,4-galactosyltransferase (β1,4-GT) are responsible for terminal sialylation and galactosylation, respectively. Enhanced sialylation of human erythropoietin (EPO) by the expression of α2,3-ST and β1,4-GT was achieved using recombinant Chinese hamster ovary (CHO) cells (EC1). The sialic acid content and sialylation of N-glycans were evaluated by HPLC. When α2,3-ST was expressed in CHO cells (EC1-ST2), the sialic acid content (moles of sialic acid/mole of EPO) increased from 6.7 to 7.5. In addition, the amount of trisialylated glycans increased from 17.3% to 26.1%. When α2,3-ST and β1,4-GT were coexpressed in CHO cells (EC1-GTST15), the degree of sialylation was greater than that in EC1-ST2 cells. In the case of EC1-GTST15 cells, the sialic acid content increased to 8.2 and the proportion of trisialylated glycans was markedly increased from 17.3% to 35.5%. Interestingly, the amount of asialoglycans decreased only in the case of GTST15 cells (21.4% to 14.2%). These results show that coexpression of α2,3- ST and β1,4-GT is more effective than the expression of α2,3-ST alone. Coexpression of α2,3-ST and β1,4-GT did not affect CHO cell growth and metabolism or EPO production. Thus, coexpression of α2,3-ST and β1,4-GT may be beneficial for producing therapeutic glycoproteins with enhanced sialylation in CHO cells.
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KEYWORD
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Glycosylation, sialylation, recombinant erythropoietin, sialyltransferase, galactosyltransferase
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