Application of Anoxia for the Enhanced Production of hCTLA4Ig in Transgenic Rice Cell Suspension Cultures

초록

To enhance the production of human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4Ig) in transgenic rice cell suspension cultures, anoxia conditions were applied to the production phases. When anoxia was applied in sugar-depleted induction media, cell viability decreased rapidly and protease activity increased more than that in aerobic conditions. However, the maximum production of hCTLA4Ig with sugar-depleted anoxia was the same as that in aerobic conditions. In addition, the production of hCTLA4Ig under anoxia conditions reached a peak 2 days earlier compared to aerobic conditions. In contrast to sugar-depleted anoxia, addition of 30 mM of glucose at the production phases markedly improved cell viability by ethanolic fermentation under anoxia conditions. A viability level of more than 65% could be maintained up to 30 days. Furthermore, the RAmy3D promoter was induced under anoxia conditions despite the presence of 30 mM of glucose. In addition, the production period of hCTLA4Ig was expanded up to 30 days, and the maximum production levels were 29 mg/L of hCTLA4Ig under anoxia compared to 14 mg/L in aerobic conditions. The overall production of hCTLA4Ig under anoxia with 30 mM of glucose was higher than that in aerobic conditions. This study demonstrates that anoxia could be an important condition for enhancing productivity in transgenic rice cell suspension cultures.