Transient Gene Expression in Chinese Hamster Ovary Cells at Low Temperature – The Effects of Cold-Induced Proteins and an mRNA Regulatory Element

Abstract

Exposure of transfected Chinese hamster ovary (CHO) cells to low temperature increased transient recombinant protein yield up to 18-fold. This phenomenon was not plasmid specific, but the enhancement of protein production under hypothermic conditions varied from 2- to 18-fold depending both on the reporter gene and the presence or absence of the woodchuck hepatitis virus post-transcriptional regulatory element (WPRE). When located in the 3′-untranslated region (UTR) of the transgene it increased protein production 3-fold at 31°C compared to expression from the isogenic plasmid without the element. Cold shock proteins are also known to act in a post-transcriptional manner, but the overexpression of the cold-induced RNA binding protein (CIRBP) and the RNA binding motif 3 (Rbm3) had no effect on the enhancement of transient recombinant protein production in CHO cells.