Influence of cytoskeleton organization on recombinant protein expression by CHO cells

In this study, we assessed the importance of cytoskeleton organization in the mammalian cells used to produce therapeutic proteins. Two cytoskeletal genes, Actin alpha cardiac muscle 1 (ACTC1) and a guanosine triphosphate GTPase‐activating protein (TAGAP), were found to be upregulated in highly productive therapeutic protein‐expressing Chinese hamster ovary (CHO) cells selected by the deprivation of vitamin B5. We report here that the overexpression of the ACTC1 protein was able to improve significantly recombinant therapeutic production, as well as to decrease the levels of toxic lactate metabolic by‐products. ACTC1 overexpression was accompanied by altered as well as decreased polymerized actin, which was associated with high protein production by CHO cell cultured in suspension. We suggest that the depolymerization of actin and the possible modulation of integrin signaling, as well as changes in basal metabolism, may be driving the increase of protein secretion by CHO cells. Pourcel et al. observed that several cytoskeletal genes are upregulated in highly productive CHO cell clones. Actin alpha overexpression yielded altered cytoskeletal organization, which was accompanied by improved recombinant therapeutic production as well as decreased levels of toxic lactate metabolic by‐products. Cells spontaneously displaying low actin polymerization yielded higher protein production in suspension cultures, highlighting the importance of the cytoskeleton for the efficient production of easy‐ as well as difficult‐to‐express therapeutic proteins.