GENETIC-ENGINEERING OF HYBRIDOMA GLUTAMINE-METABOLISM

The murine hybridoma PQXB1/2 cannot be adapted to grow in culture medi a containing <0.5 mM glutamine. Transformants selected following elect roporation of PQXB1/2 cells with vectors containing a Chinese hamster glutamine synthetase (GS) cDNA under the control of the SV40 early pro moter also failed to grow in the absence of glutamine in the culture m edium. PQXB1/2 cells have, however, been transformed to glutamine inde pendence following electroporation with a vector containing this gluta mine synthetase cDNA under the control of the human cytomegalovirus im mediate early promoter. In these cells, sufficient active glutamine sy nthetase was expressed from one vector per cell to enable growth in gl utamine-free media. The specific activity of glutamine synthetase in t wo transformed cell lines producing parental levels of antibody was in creased by 128 and 152%, respectively (0.57 and 0.63 mu mol min(-1) pe r 10(6) cells in transformants compared with parental levels of 0.25 m u mol min(-1) per 10(6) cells). This reprogramming of glutamine synthe tase expression and glutamine metabolism is important for developing s trategies to deal with ammonia toxicity and the production of cell lin es with improved metabolic processes.