201. C105Y, a Novel Cell Penetrating Peptide Enhances Gene Transfer of Sec-R Targeted Molecular Conjugates

Abstract

We have used poly-L-lysine (polyK) condensed DNA complexes to deliver DNA to cells both in vitro and in vivo. In order to target and increase cellular uptake of these complexes, we covalently attached a small peptide ligand, C105Y (CSIPPEVKFNKPFVYLI), to polyK before DNA condensation. This peptide was initially identified as an amino acid sequence within the carboxy-terminal tail of a1-antitrypsin (a1-AT) that could mediate binding to the serpin enzyme complex receptor (sec-R). This putative receptor was characterized, mainly by biochemical means as a cell surface binding site on human hepatoma HepG2 cells and blood monocytes. The synthetic peptide C105Y based on amino acids sequence 346-374 of a1-AT, competed with the natural ligand for binding to the sec-R and provided gene transfer into cells when it was conjugated to polyK - DNA complexes. These particles, which average <50 nm in diameter by EM, provide gene transfer of the CFTR gene in vivo to airway epithelial cells from CFTR deficient mice.