Expression of carbamoyl phosphate synthetase I and ornithine transcarbamoylase genes in Chinese hamster ovary dhfr-cells decreases accumulation of ammonium ion in culture media

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• 作者：Park ; Hyo-Soon ; Kim ; Ik-Hwan ; Kim ; Ick-Young ; Kim ; Ki-Ho ; Kim ; Hong-Jin
• 关键词：Carbamoyl phosphate synthetase ; Ornithine transcarbamoylase ; Ammonium ion ; CHO cells ; Urea cycle
• 刊名：Journal of Biotechnology
• 出版年：2000
• 出版时间：August 25, 2000
• 年：2000
• 卷：81
• 期：2-3
• 页码：129-140
• 全文大小：267 K

文摘

Ammonium ion accumulation in mammalian cell culture media causes toxicity which inhibits cell growth and productivity. To reduce the level of the accumulated ammonium ion, carbamoyl phosphate synthetase I (CPS I) and ornithine transcarbamoylase (OTC) were used, which catalyze the first and second steps of the urea cycle in the liver. To examine the effects of overexpressed CPS I and OTC genes on the concentration of the ammonium ion in culture media, the two genes were introduced into Chinese hamster ovary (CHO) dhfr-cells. The CPS I expressing cell lines (CPS I-CHO) and both CPS I and OTC expressing cell lines (CPS I/OTC-CHO) were confirmed at the mRNA level and analyzed in terms of the cell growth and the accumulation of ammonium ion in culture media. The accumulation of ammonium ion was 25–33 % less in CPS I/OTC-CHO than in either CPS I-CHO or the vector-control cell lines. Interestingly however, the cell growth was 15–30 % faster in both CPS I-CHO and CPS I/OTC-CHO than in the control cell lines. Forced expression of urea cycle enzymes in the CHO cells revealed that both the expression of CPS I and OTC can reduce the accumulation of ammonium ion in the culture media.