Proteome analysis of antibody-expressing CHO cells in response to hyperosmotic pressure

To better understand intracellular responses to hyperosmotic pressure of recombinant Chinese hamster ovary (rCHO) cells expressing an antibody, we have taken a proteomics approach. Using two-dimensional electrophoresis and mass spectrometry, a proteome profile of rCHO cells comprising 23 identified proteins was established. On the basis of this proteome profile, we found three proteins of which expression levels were significantly changed at 450 mOsm/kg. Compared to the results at 300 mOsm/kg, two glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase, were found to be up-regulated, probably leading to an increased metabolic energy for antibody synthesis. The elevation of specific glucose consumption rate at 450 mOsm/kg agreed with the up-regulation of these glycolytic enzymes. On the other hand, tubulin expression was down-regulated, reflecting a depressed cell growth rate at 450 mOsm/kg. Taken together, this study shows the potential of the proteomics approach in understanding intracellular and physiological changes in cells and seeking a better insight into possible environmental or genetic manipulation approaches for increasing foreign protein production in rCHO cells.