A transfecting peptide derived from adenovirus fiber protein

New strategies to improve the outcome of gene therapy often employ a nonviral gene delivery, which is most likely to fulfil microbiological safety criteria and be retained in the clinical setting. Here we show that efficient gene transfer can be achieved in vitro using as a vector a polyvalent peptide derived from the N-terminal sequence of the human adenovirus fiber protein. The level of transfection is better than that obtained with the two liposomes, DOTAP and DOSPER. Internalization was studied by confocal microscopy using fluorescently marked peptide and DNA. The peptide alone is targeted to the nucleus and concentrated within the nucleolus. Similarly, DNA complexed with peptide also enters the nucleolus, where it is retained for at least 48 h. Peptide I appears to attach to cells by a saturable process, as preincubation of cells with peptide blocks transfection and there is no transfection at 4 degrees C. The peptide contains three domains: a nuclear localization signal of adenovirus fiber protein; a domain containing hydrophobic and polar residues harboring an internalization signal for receptor-mediated endocytosis; and a stretch of lysines. Each of these domains is required for optimum gene transfer. Peptide I may be an interesting alternative to known vectors for gene transfer, for local administration and for ex vivo applications.