Use of a new genetic element to improve expression level of cell lines for recombinant protein production

Background Naturally occurring chromatin modifying elements such as MAR, UCOE or cHS4 were identified from the genome of higher eukaryotes. It is well documented that the presence of these regulatory elements leads to better recruitment of transcriptional machinery and/or prevents epigenetic silencing mechanisms [1,2]. The goal of this work was the evaluation of a new genetic element to improve transgene expression, from the flanking sequences of the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene, which is a ubiquitously expressed enzyme. It was hypothesized that the surrounding genetic environment of the gene may lead to a DNA structure favorable for transgene expression in eukaryotes. In this study, we have investigated the effect on stable and transient expression in CHO and HEK293 cells of the 3.2 kilo base pairs (kb) sequences flanking upstream (5’) and downstream (3’) the GAPDH locus.