Reduction-sensitive polypeptides incorporated with nuclear localization signal sequences for enhanced gene delivery

Abstract

A series of peptide-based vectors (PolyR₈, PolyR₈-NLS₁, PolyR₈-NLS₂ and PolyR₈-NLS₃) containing R₈ sequences linked by disulfide bonds are explored as gene vectors. To overcome the nuclear membrane barrier, nuclear localization signal (NLS) sequences were also introduced to these vectors for nuclear import. It was found that all the vectors except PolyR₈-NLS₃ were efficient for binding and condensing plasmid DNA (pDNA). PolyR₈ without an NLS sequence exhibited a relatively high cytotoxicity, while PolyR₈-NLS (PolyR₈-NLS₁, PolyR₈-NLS₂ and PolyR₈-NLS₃) displayed low cytotoxicity. Moreover, with the increasing amount of NLS sequences, the cytotoxicity of PolyR₈-NLS decreased. PolyR₈-NLS₂ possessed the highest transfection efficiency at a w/w ratio of 40, which was comparable to jetPEI™. According to the result of flow cytometry, the percentage of cells transfected by PolyR₈-NLS₂ was 35.7%, which was even superior to that of jetPEI™ (32.0%). PolyR₈-NLS₂ also presented the best capability for nuclear targeting from the confocal microscopy observations.