Reduction of Protein Degradation by Using Protein-stabilizing Agents in Transgenic Rice Cell Cultures

초록

Human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4Ig) was expressed in transgenic rice cell cultures using RAmy3D promoter which is induced by sugar starvation. RAmy3D promoter has been used as an effective tool to increase the expression, but the sugar starvation condition causes cell death and triggers the release of proteases by cell lysis. Consequently the target protein is degraded rapidly by protease. Also protein production in bioreactors is greatly affected by physical factors such as aeration and agitation [1]. High aeration rates in plant cell cultures may result in severe foaming which can inhibit cell growth and high agitation rates induce shear damage, reducing cell growth and production of recombinant proteins. In order to reduce the degradation of hCTLA4Ig by aeration, agitation and proteases, protection effects of protein-stabilizing agents such as polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were evaluated [2]. It was found that these agents lowered the degradation of target protein by plant proteases and improved the production level in transgenic rice cell cultures. In conclusion, supplementation of 0.1 g/L PVA and 0.5 g/L PVP enhanced hCTLA4Ig production 1.5-fold and 2.8-fold, respectively.