Nuclear targeting peptide scaffolds for lipofection of nondividing mammalian cells

Lipofection of nondividing cells is inefficient because much of the transfe cted DNA is retained in endosomes, and that which escapes to the cytoplasm enters the nucleus at low rates. To improve the final rate-limiting step of nuclear import, we conjugated a nonclassical nuclear localization signal ( NLS) containing the M9 sequence of heterogeneous nuclear ribonucleoprotein (hnRNP) A1, to a cationic peptide scaffold derived from a scrambled sequenc e of the SV40 T-antigen consensus NLS (ScT). The ScT was added to improve D NA binding of the M9 sequence. Lipofection of confluent endothelium with pl asmid complexed with the M9-ScT conjugate resulted in 83% transfection and a 63-fold increase in marker gene expression. The M9-ScT conjugate localize d fluorescent plasmid into the nucleus of permeabilized cells, and addition of the nuclear pore blocker wheat germ agglutinin prevented nuclear import . This method of gene transfer may lead to viral- and lipid-free transfecti on of nondividing cells.