ABSTRACT
The Chinese hamster ovary (CHO) cell line is the most widely used host cell for therapeutic antibody production. Although its productivity has been improved by various strategies to satisfy the growing global demand, some difficult-to-express (DTE) antibodies remain at low secretion levels. To improve the production of various therapeutic antibodies, it is necessary to determine possible rate-limiting steps in DTE antibody secretion in comparison with other high IgG producers. Here, we analyzed the protein secretion process in CHO cells producing the DTE immunoglobulin G (IgG) infliximab. The results from chase assays using a translation inhibitor revealed that infliximab secretion could be nearly completed within 2 h, at which time the cells still retained about 40% of heavy chains and 65% of light chains. Using fluorescent microscopy, we observed that these IgG chains remained in the endoplasmic reticulum and Golgi apparatus. The cells inefficiently form fully assembled heterodimer IgG by making LC aggregates, which may be the most serious bottleneck in the production of DTE infliximab compared with other IgG high producers. Our study could contribute to establish the common strategy for constructing DTE high-producer cells on the basis of rate-limiting step analysis.
ABSTRACT
A series of the earthquake response analyses of a curved Menshin bridge were carried out using an anlytical approach in which the non-linear behavior in the shear deformation of the Menshin bearing is be able to taken into consideration. It was found that the seismic responses at an individual substructure and Menshin bearings in the tangetial direction to the deck axis are larger than the corresponding responses of the straight bridge in the longitudinal direction, while the seismic responses in the normal direction are smaller than the corresponding responses of the straight bridge in the transverse direction.(AU)