Comparison of Sugar Uptake between Wild-type and Glycoengineered Rice Cells in Suspension Cultures

초록

N-glycans of proteins are important for their safety as well as efficacy in biopharmaceuticals. N-glycosylation pathway is different between mammalian and plant cells. For this reason, the use of plant-made pharmaceuticals (PMPs) has potential cause of immunogenicity. For that reason, glycoengineering is required for the humanization of plant-derived N-glycans [1, 2]. N-acetylglucosaminyltransferase 1 (gnt1) knockout is known to be an effective glycoengineering strategy that expresses high-mannose N-glycans lacking plant-specific residues. However, modulation of N-glycan has a possibility to affect the physiological characteristics of the cultured cells [3]. Therefore, comparison of different characteristics between wild-type (WT) and glycoengineered cells should be performed for the production of PMPs. In this study, various disaccharides (sucrose, maltose, lactose, trehalose) and monosaccharides (glucose, fructose, mannose, galactose, ribose, xylose) were added into culture medium as a carbon source. Among them, three kinds of carbon sources (sucrose, ribose, maltose) displayed different sugar uptake behavior between WT and glycoengineered rice cells. Glycoengineered cells showed high conversion of sucrose to glucose and fructose. When ribose was added into culture medium, high consumption rate was displayed in glycoengineered cells. However, WT showed low conversion of sucrose and consumption rate of ribose. Especially, rapid cleavage and uptake of maltose was shown in WT. WT completely consumed maltose at day 8, whereas glycoengineered cells did not. Except sucrose, ribose and maltose, similar sugar uptake behavior was showed between WT and glycoengineered rice cells. In conclusion, it was found that gnt1 knockout in rice cells could significantly influence sugar uptake behavior.