Molecular Characteristic of MAR that Increases Transgene Expression in Recombinant CHO Cells

The aim of this study was to analyze the molecular characteristics and identify the key elements of matrix attachment regions( MARs) that can improve transgene expression in stably transfected CHO cells. β-globin MAR was divided into six sub-fragments( position 1 ~ 540,421 ~ 1 020,901 ~ 1 500,1 381 ~ 1 980,1 861 ~ 2 460,2 341 ~ 2 999) from 5' to 3' end. These sub-fragments were gradually respectively cloned via PCR technology,and then inserted into upstream of SV40 promoter of expression vector including chloramphenicol acetyltransferase( CAT) reporter gene expression cassette,followed by transfection into CHO cells and screened under G418. The CAT reporter gene expression was analyzed by ELISA. The sequence characteristic of each fragment was analyzed by bioinformatics. The results showed that the overall length of β-globin MAR can significantly improve the expression level of CAT. The second and third sub-fragments( position 421 ~ 1 020,901 ~ 1 500) showed the most effective compared to other sub-fragments. The bioinformatics analysis results showed that MAR-like motif of MAR may contribute to the upregulation of transgene expression.