Kimura R, Miller W M
Chemical Engineering Department, Northwestern University, Evanston, Illinois 60208-3120, USA.
Biotechnol Prog. 1997 May-Jun;13(3):311-7. doi: 10.1021/bp9700162.
Carbon dioxide is a metabolic byproduct of mammalian cell metabolism that can accumulate in poorly ventilated cultures. A buildup of CO2 at constant pH will be accompanied by an increase in medium osmolality. We have examined the glycosylation of tissue plasminogen activator (tPA) produced under serum-free conditions by recombinant Chinese hamster ovary (CHO) cells (MT2-1-8 cell line) in response to elevated pCO2 at constant or elevated osmolality. The proportion of sialic acids comprising N-glycolylneuraminic acid decreased from 2.3-4.0% under 36 mmHg pCO2 to 1.5-2.2% under 250 mmHg pCO2. No changes were observed in the total sialic acid content, the content of other monosaccharides, the relative amounts of type I and type II tPAs, the distribution of surface charges, or the proportion of high-mannose oligosaccharides-even though these conditions have previously been shown to inhibit the specific growth rate of MT2-1-8 cells by 30-40% and the specific tPA production rate by as much as 40%. These results suggest robust glycosylation of tPA by CHO cells.
二氧化碳是哺乳动物细胞代谢的一种副产物，可在通风不良的培养环境中蓄积。在恒定pH值下，二氧化碳的蓄积会伴随着培养基渗透压的升高。我们研究了重组中国仓鼠卵巢（CHO）细胞（MT2-1-8细胞系）在无血清条件下产生的组织型纤溶酶原激活剂（tPA）的糖基化情况，该细胞系在恒定或升高的渗透压下对升高的pCO2作出反应。在36 mmHg pCO2条件下，构成N-羟乙酰神经氨酸的唾液酸比例从2.3 - 4.0%降至250 mmHg pCO2条件下的1.5 - 2.2%。在总唾液酸含量、其他单糖含量、I型和II型tPA的相对量、表面电荷分布或高甘露糖寡糖比例方面均未观察到变化——尽管此前已表明这些条件会使MT2-1-8细胞的比生长速率降低30 - 40%，使tPA的比产生速率降低多达40%。这些结果表明CHO细胞对tPA具有强大的糖基化作用。
