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Glycoengineering of Chinese hamster ovary cells for enhanced erythropoietin N‐glycan branching and sialylation
Author(s) -
Yin Bojiao,
Gao Yuan,
Chung Chengyu,
Yang Shuang,
Blake Emily,
Stuczynski Mark C.,
Tang Juechun,
Kildegaard Helene F.,
Andersen Mikael R.,
Zhang Hui,
Betenbaugh Michael J.
Publication year - 2015
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.25650
Subject(s) - chinese hamster ovary cell , sialic acid , glycan , glycosylation , sialyltransferase , glycoprotein , biochemistry , glycosyltransferase , chemistry , recombinant dna , biology , enzyme , receptor , gene
Sialic acid, a terminal residue on complex N‐glycans, and branching or antennarity can play key roles in both the biological activity and circulatory lifetime of recombinant glycoproteins of therapeutic interest. In order to examine the impact of glycosyltransferase expression on the N‐glycosylation of recombinant erythropoietin (rEPO), a human α2,6‐sialyltransferase (ST6Gal1) was expressed in Chinese hamster ovary (CHO‐K1) cells. Sialylation increased on both EPO and CHO cellular proteins as observed by SNA lectin analysis, and HPLC profiling revealed that the sialic acid content of total glycans on EPO increased by 26%. The increase in sialic acid content was further verified by detailed profiling of the N‐glycan structures using mass spectra (MS) analysis. In order to enhance antennarity/branching, UDP‐ N ‐acetylglucosamine: α‐1,3‐D‐mannoside β1,4‐ N ‐acetylglucosaminyltransferase (GnTIV/Mgat4) and UDP‐ N ‐acetylglucosamine:α‐1,6‐D‐mannoside β1,6‐ N ‐acetylglucosaminyltransferase (GnTV/Mgat5), was incorporated into CHO‐K1 together with ST6Gal1. Tri‐ and tetraantennary N‐glycans represented approximately 92% of the total N‐glycans on the resulting EPO as measured using MS analysis. Furthermore, sialic acid content of rEPO from these engineered cells was increased ∼45% higher with tetra‐sialylation accounting for ∼10% of total sugar chains compared to ∼3% for the wild‐type parental CHO‐K1. In this way, coordinated overexpression of these three glycosyltransferases for the first time in model CHO‐K1 cell lines provides a mean for enhancing both N‐glycan branching complexity and sialylation with opportunities to generate tailored complex N‐glycan structures on therapeutic glycoproteins in the future. Biotechnol. Bioeng. 2015;112: 2343–2351. © 2015 Wiley Periodicals, Inc.