Co-immunoprecipitated human proteins with tobacco NtFT4

Biopharmaceutical proteins are produced in mammalian cells by transient expression or stable transformation, but both processes require robust and viable cells. Cell line engineering must therefore balance improved cell growth and viability with high productivity. We tested the expression of non-mammalian phosphatidylethanolamine binding proteins to enhance cell proliferation. The tobacco protein NtFT4 improved the proliferation and viability of HEK-293T cells in animal component-free suspension cultures. Viable cell density is usually impaired by efficient transfection, but we found that the number of HEK-293TNtFT4 cells doubled at the peak of protein expression and the antibody yield increased by approximately one third. The improved growth and viability were observed in different cell backgrounds, suggesting the system is transferable. Furthermore, high densities of viable HEK-293TNtFT4 cells will allow further modifications to boost protein synthesis. The established HEK-293TNtFT4 cell line provides a new human cell platform that increases cell proliferation without sacrificing translational activity.