Protein transduction by pseudotyped lentivirus-like nanoparticles

A simple, efficient and reproducible method to transduce proteins into mammalian cells has not been established. Here we describe a novel protein transduction method based on a lentiviral vector. We have developed a method to package several thousand foreign protein molecules into a lentivirus-like nanoparticle (LENA) and deliver them into mammalian cells. In this proof-of-concept study, we used β-lactamase (BlaM) as a reporter molecule. The amino-terminus of BlaM was fused to the myristoylation signal of lyn, which was placed upstream of the amino-terminus of Gag (BlaM-gag-pol). By co-transfection of plasmids encoding BlaM-gag-pol and vesicular stomatitis virus-G (VSV-G) into 293T cells, LENA were produced containing BlaM enzyme molecules as many as Gag per capsid, which has been reported to be ∼5000 molecules, but lacking the viral genome. Infection of 293T and MT-4 cells by VSV-G-pseudotyped BlaM-containing LENA led to successful transduction of BlaM molecules into the cell cytoplasm, as detected by cleavage of the fluorescent BlaM substrate CCF2-AM. LENA-mediated transient protein transduction does not damage cellular DNA, and the preparation of highly purified protein is not necessary. This technology is potentially useful in various basic and clinical applications.