Exploiting viral cell-targeting abilities in a single polypeptide, non-infectious, recombinant vehicle for integrin-mediated DNA delivery and gene expression

A recombinant, multifunctional protein has been designed for optimized, cel l-targeted DNA delivery and gene expression in mammalian cells. This hybrid construct comprises a viral peptide ligand for integrin alpha(v)beta(3) bi nding, a DNA-condensing poly-L-lysine domain, and a complete, functional be ta-galactosidase protein that serves simultaneously as purification tag and DNA-shielding agent. This recombinant protein is stable; it has been produ ced successfully in Escherichia coil and can be purified in a single step b y affinity chromatography. At optimal molar ratios, mixtures of this vector and a luciferase-reporter plasmid form stable complexes that transfect cul tured cells. After exposure to these cell-targeted complexes, steady levels of gene expression are observed for more than 3 days after transfection, r epresenting between 20 and 40% of those achieved with untargeted, lipid-bas ed DNA-condensing agents. The principle to include viral motifs for cell in fection in single polypeptide recombinant proteins represents a promising a pproach towards the design of non-viral modular DNA transfer vectors that c onserve the cell-targeting specificity of native viruses and that do not ne ed further processing after bioproduction in a recombinant host. (C) 2000 J ohn Wiley & Sons, Inc.