MAR-Mediated Integration of Plasmid Vectors for In Vivo Gene Transfer and Regulation

In this study, scientists devised vectors allowing a tight regulation of transgene expression in mice  from such non-viral vectors using a doxycycline-controlled network of activator and  repressor proteins. Using these vectors, we demonstrate proper physiological response as  consequence of the induced expression of two therapeutically relevant proteins, namely  erythropoietin and utrophin. Kinetic studies showed that the induction of transgene  expression was only transient, unless epigenetic regulatory elements termed Matrix  Attachment Regions, or MAR, were inserted upstream of the regulated promoters. Using  episomal plasmid rescue and quantitative PCR assays, we observed that similar amounts of  plasmids remained in muscles after electrotransfer with or without MAR elements, but that a  significant portion had integrated into the muscle fiber chromosomes. Interestingly, the MAR  elements were found to promote plasmid genomic integration but to oppose silencing effects  in vivo, thereby mediating long-term expression.

This article is published online in BMC Molecular Biology and is free to access.