A small, synthetic peptide for gene delivery via the serpin–enzyme complex receptor

✍ Scribed by Sheetal Patel; Xiaohong Zhang; Louise Collins; John W. Fabre

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 237 KB
• Volume: 3
• Category: Article
• ISSN: 1099-498X
• DOI: 10.1002/jgm.180

✦ Synopsis

Background The serpin-enzyme complex receptor (SECR) has previously been successfully targeted for gene delivery using synthetic peptide ligands covalently linked in fluid phase to commercially available polylysine preparations (y10-54 kDa). The objective of the present study was to improve this approach by the use of small, bifunctional, and easily standardised synthetic peptides.

Methods Two synthetic peptides designated polylysine antitrypsin 1 (PAT1) (K 16 FNKPFVFLI) and PAT2 (K 16 CSIPPEVKFNKPFVFLI) were evaluated for gene delivery to the HUH7 human hepatocyte cell line. The K 16 moiety binds DNA electrostatically, while the FVFLM motif of human a 1 -antitrypsin targets the SECR.

Results Both PAT1 and PAT2 bind to and condense DNA into small particles as shown by laser scattering techniques. However, only PAT2 is effective for gene delivery, presumably on account of the greater distance between the K 16 chain and the FVFLM motif. Gene delivery by PAT2/DNA complexes is chloroquine-dependent, can be blocked completely by free ligand (CSIPPEVKFNKPFVFLI), and is highly efficient (e.g. approximately five-fold more effective than lipofectamine). At physiological salt concentrations, PAT2/DNA complexes formed at 4 mg/ml DNA are y350 nm in diameter and highly effective for gene transfer, but at 100 mg/ml DNA the complexes are aggregated (diameter >4 mm) and inactive.

Conclusions A small (33 amino acid), bifunctional, synthetic peptide represents a highly efficient and readily standardised DNA vector for the SECR. The effectiveness of this peptide depends on the distance of the K 16 moiety from the targeting ligand. High salt concentrations are not required to form effective vector/DNA complexes.