Integrated Genome and Protein Editing Swaps α-2,6 Sialylation for α-2,3 Sialic Acid on Recombinant Antibodies from CHO

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• 作者：Cheng-yu Chung ; Qiong Wang ; Shuang Yang ; Bojiao Yin ; Hui Zhang and Michael Betenbaugh
• 刊名：Biotechnology Journal
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：12
• 期：2
• 全文大小：1117K
• ISSN：1860-7314

文摘

Immunoglobin G with α-2,6 sialylation has been reported to have an impact on antibody-dependent cellular cytotoxicity and anti-inflammatory efficacy. However, production of antibodies with α-2,6 sialylation from Chinese hamster ovary cells is challenging due to the inaccessibility of sialyltransferases for the heavy chain N-glycan site and the presence of exclusively α-2,3 sialyltransferases. In this study, combining mutations on the Fc regions to allow sialyltransferase accessibility with overexpression of α-2,6 sialyltransferase produced IgG with significant levels of both α-2,6 and α-2,3 sialylation. Therefore, ST3GAL4 and ST3GAL6 genes were disrupted by CRISPR/Cas9 to minimize the α-2,3 sialylation. Sialidase treatment and SNA lectin blot indicated greatly increased α-2,6 sialylation level relative to α-2,3 sialylation for the α-2,3 sialyltransferase knockouts when combined with α-2,6 sialyltransferase overexpression. Indeed, α-2,3 linked sialic acids were not detected on IgG produced from the α-2,3 sialyltransferase knockout-α-2,6 sialyltransferase overexpression pools. Finally, glycoprofiling of IgG with four amino acid substitutions expressed from an α-2,3 sialyltransferase knockout-α-2,6 sialyltransferase stable clone resulted in more than 77% sialylated glycans and more than 62% biantennary disialylated glycans as indicated by both MALDI-TOF and LC-ESI-MS. Engineered antibodies from these modified Chinese hamster ovary cell lines will provide biotechnologists with IgGs containing N-glycans with different structural variations for examining the role of glycosylation on protein performance.