Improvement of transient protein production by COS-1 cells stably overexpressing bcl-2 gene

摘要

COS-1 cells were transfected with human bcl-2 gene by using plasmid vector BCMGS-neo derived from bovine papilloma virus type-1: the plasmid can multiply in nucleus of mammalian cells. The transfectants overexpressed human Bcl-2 and showed remarkably improved survival when cultured at low (0.2percent) serum concentration. This survival indicated that Bcl-2 protein functioned in COS_1 cells and then prevented the bcl-2 transfectants from apoptosis caused by serum limitation. For examining efficiency of protein productivity. the bcl-2 transfectants were further transfected with mouse lambda chain cDNA carried by an SV40-derived plasmid for transient expression. The culture supernatant of the bcl-2 transfectants and control cells was sampled on day 4, 5, 6, 7, and 14 posttransfection. Control cells almost stopped producing lambda chain on day 6 posttransfection. On the other hand the bcl-2 transfectants continued production after day 7, producing twofold amound of the lambda chain in total in comparison with control, presumably because Bcl-2 suppressed apoptosis in late culture. These COS-1 cells stably overexpressing Bcl-2 will be advantageous for transient expression of recombinant proteins.