Improved Production of hCTLA4Ig with Sodium Pyruvate in Transgenic Rice Cell Cultures

초록

Human cytotoxic T lymphocyte-associated antigen 4-immunoglobulin (hCTLA4Ig), an immunosuppressive agent, was expressed in transgenic rice cells using RAmy3D promoter and RAmy1A signal peptide for the inducible production and secretion into culture media by sugar depletion. Since the target protein is produced by starvation of sugar, there are no energy sources during the production phase of cultures. For this reason, the viability of the cells is reduced after induction. We tried to overcome this problem by adding alternative energy sources in this study. To improve the productivity of hCTLA4Ig, pyruvic acid and sodium pyruvate were added in transgenic rice cell cultures. When 87 and 174 mM pyruvic acid were added during the production phase, the viability of the cells has been similar to that of control. However, no hCTLA4Ig was produced. It has been shown that pyruvic acid was not an effective energy source in this system. Both concentrations (87, 174 mM) of sodium pyruvate were also investigated to determine the optimal level. When 87mM sodium pyruvate was added in sugar-free media, the rate of cell death was decreased and the production of hCTLA4Ig was increased. The viability of cultures without sodium pyruvate was almost zero at day 6. However, by adding sodium pyruvate, 18% of viability could be kept until the tenth day. In addition, the production of hCTLA4Ig could be increased 1.4 fold.