RESUMEN
Ubiquitous chromatin opening element ( UCOE ) , composed of the promoters of human housekeeping genes, prevents transgene from silencing and produces consistent, stable and high-level gene expression irrespec-tive of the chromosomal integration site. The research studied the influence of different UCOE element parts on antibody expression in CHO cells. UCOE 1. 5 kb from chromobox homolog 3 ( CBX3 ) , UCOE 2. 5 kb from the heterogeneous ribonucleoprotein A2/B1 ( HNRPA2 B1 ) and the whole UCOE 4. 0 kb were inserted into the anti-body light and heavy chain vectors, respectively, and transfected into CHO cells using antibiotics-Zeocin and Blasticidin for pressure selection. Four groups of monoclonal cells were harvested and antibody expression of each group was detected. The monoclonal cells with UCOE 1. 5 kb and UCOE 2. 5 kb increased 1. 5 to 2-fold in the level of antibody expression, wheareas, monoclonal cells with UCOE 4. 0 kb increased 3 to 4-fold. The enhance-ment of two housekeeping promoter genes on antibody expression could stack up.