title: A potent new class of reductively activated peptide gene delivery agents.
abstract: A new class of peptide gene delivery agents were developed by inserting multiple cysteine residues into short (dp 20) synthetic peptides. Substitution of one to four cysteine residues for lysine residues in Cys-Trp-Lys(18) resulted in low molecular weight DNA condensing peptides that spontaneously oxidize after binding to plasmid DNA to form interpeptide disulfide bonds. The stability of cross-linked peptide DNA condensates increased in proportion to the number of cysteines incorporated into the peptide. Disulfide bond formation led to a decrease in particle size relative to control peptide DNA condensates and prevented dissociation of peptide DNA condensates in concentrated sodium chloride. Cross-linked peptide DNA condensates were 5-60-fold more potent at mediating gene expression in HepG2 and COS 7 cells relative to uncross-linked peptide DNA condensates. The enhanced gene expression was dependent on the number of cysteine residues incorporated, with a peptide containing two cysteines mediating maximal gene expression. Cross-linking peptides caused elevated gene expression without increasing DNA uptake by cells, suggesting a mechanism involving intracellular release of DNA triggered by disulfide bond reduction. The results establish cross-linking peptides as a novel class of potent gene delivery agents that enhance gene expression through a new mechanism of action.
authors.affiliation: Divisions of Medicinal Chemistry and Pharmaceutics, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109-1065, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: McKenzie
authors.forename: K Y
authors.initials: KY
authors.lastname: Kwok
authors.forename: K G
authors.initials: KG
authors.lastname: Rice
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D004220:Disulfides; D018014:Gene Transfer Techniques; D006801:Humans; D009842:Oligopeptides / Q000138:chemical synthesis / Q000302:isolation & purification; D010455:Peptides / Q000138:chemical synthesis / Q000302:isolation & purification; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis; D013314:Stress, Mechanical; D014162:Transfection / Q000379:methods*; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D004220:Disulfides; D009842:Oligopeptides; D010455:Peptides; D011994:Recombinant Proteins; D001616:beta-Galactosidase