Transfected plasmid DNA is incorporated into the nucleus via nuclear envelope reformation at telophase

Abstract DNA transfection is an important technology in the life sciences, wherein nuclear entry of DNA is necessary to achieve expression of the exogenous DNA. Non-viral vectors and their transfection reagents are useful as safe tools for transfection. However, they have no effects for transfection of non-proliferating cells, the reason for which remains unknown. This study aimed to elucidate the mechanism by which transfected DNA enters the nucleus for gene expression. To monitor the intracellular behavior of transfected DNA, we introduced a plasmid bearing lacO repeats and RFP-coding sequences into cells expressing GFP-LacI and observed plasmid behavior and RFP expression. RFP expression appeared only after mitosis. Electron microscopy showed that plasmids were wrapped with nuclear envelope (NE)-like membranes or associated with chromosomes at telophase. Depletion of BAF, which is involved in NE reformation, delayed plasmid RFP expression. These results suggest that transfected DNA is incorporated into the nucleus via NE reformation at telophase.