Application of EBV-based artificial chromosome to genetic engineering of mammalian cells and tissues

Although gene transduction offers a fundamental technology to analyze, manipulate, and regulate functions of mammalian cells, gene delivery systems so far established remains insufficient in terms of the efficiencies of delivery and expression as well as long-term stability. We have examined various non-viral gene transduction systems, including synthetic macromolecules and physical procedures, to genetically engineer a variety of cells/tissues/organs. Noteworthy, the transfer and expression efficacies are highly dependent on the nucleotide sequences employed in the DNA construct. The oriP and the Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA1) gene are two genetic elements originally derived from the EBV, and drastically improve transduction rate as well as expression level when transfected into cells. This was found mainly due to EBNA1-dependent nuclear trafficking of oriP-bearing DNA molecules inside the host cells, while transcriptional enhancement mediated by oriP/EBNA1 also partially contributed. DNA replication did not influence the transduction/expression rates. The efficient gene transduction and expression were obtained regardless whether the DNA construct was in circular or linear conformation. These characteristics of oriP/EBNA1-bearing DNA as an artificial chromosome may provide promising methodologies to manipulate and handle cellular functions in multi-scale system cell engineering approaches