Effect of co-overexpression of the cargo receptor ERGIC-53/MCFD2 on antibody production and intracellular IgG secretion in recombinant Chinese hamster ovary cells

Therapeutic antibodies are attractive biopharmaceuticals because of their high therapeutic effects, fewer side effects, and prolonged half-life in the blood. Chinese hamster ovary (CHO) cells are the most widely used host cell lines to produce therapeutic antibodies in industries. High-producing recombinant CHO cells can be established via over -expression of endogenous proteins. In this study, we focused on the intracellular traffic of an antibody-producing CHO cell line, CHO-HcD6. Assembled antibodies were accumulated in the endoplasmic reticulum (ER) in the cell. We hy-pothesized that the accumulation was due to the insufficient number of cargo receptors in the cell and focused on a cargo receptor, the ERGIC-53-MCFD2 complex, which transports expressed proteins from the ER to the Golgi apparatus. Overexpression of the cargo receptor transport was expected to improve antibody production. Exogenous ERGIC-53 and MCFD2 were transfected into CHO-HcD6 cells, and overexpressing CHO-HcD6 cells were constructed. As a result of overexpression, antibody productivity increased in batch cultivation. However, the chase assay results and immuno-fluorescence microscopic observations revealed intracellular IgG accumulation in the overexpressing cells. These results suggest that overexpression of cargo receptors not only promoted extracellular secretion but also enhanced the retention of intracellular antibodies.(c) 2022, The Society for Biotechnology, Japan. All rights reserved.

Automated summary

Therapeutic antibodies are highly effective biopharmaceuticals with fewer side effects and longer half-life in the blood. This study focused on the intracellular trafficking of antibody-producing CHO cells and identified the accumulation of antibodies in the endoplasmic reticulum (ER) due to insufficient cargo receptors. Overexpression of the cargo receptor complex, ERGIC-53-MCFD2, improved antibody production but also increased intracellular antibody retention.