title: Unique features of a pH-sensitive fusogenic peptide that improves the transfection efficiency of cationic liposomes.
abstract: BACKGROUND
  One of the critical steps in intracellular gene delivery using cationic liposomes is the endosomal escape of the plasmid/liposome complexes to the cytosol. The addition of GALA, a pH-sensitive fusogenic peptide, is a promising method to accelerate this step in order to enhance the expression of the desired proteins. Detailed studies on the methods of enhancement would broaden the horizon of its application.
  
  
  METHODS
  Using representative commercially available cationic liposomes (Lipofectin, Lipofectamine, and Lipofectamine 2000), the effects of GALA on transfection efficiency were studied by luciferase assay and confocal microscopic observations.
  
  
  RESULTS
  A concentration-dependent increase in the transfection efficiency was observed for GALA. Addition of 0.1 microM GALA to the plasmid/liposome complex significantly increased the transfection efficiency, especially in the case of Lipofectin, but higher concentration of GALA decreased transfection efficiency. Successful reduction in the liposomal dosage was attained by employing GALA while maintaining a high transfection efficiency. Interestingly, although the transfection efficiency was higher in the presence of GALA, a lower amount of the plasmid DNA was taken up by the cells. Confocal microscopic observations of the rhodamine-labeled plasmid did not show a significant difference in the cellular localization among cells incubated in the presence or absence of GALA, suggesting that a slight increase in GALA-induced release of the plasmid to the cytosol may cause a significant change in the transfection efficiency.
  
  
  CONCLUSIONS
  The unique features of GALA to mediate improved transfection efficiencies were identified.
authors: Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan. futaki@scl.kyoto-u.ac.jp
authors: Shiroh
authors: S
authors: Futaki
authors: Yumi
authors: Y
authors: Masui
authors: Ikuhiko
authors: I
authors: Nakase
authors: Yukio
authors: Y
authors: Sugiura
authors: Takashi
authors: T
authors: Nakamura
authors: Kentaro
authors: K
authors: Kogure
authors: Hideyoshi
authors: H
authors: Harashima
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004337:Drug Carriers / Q000378:metabolism; D005822:Genetic Vectors; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000378:metabolism; D008055:Lipids / Q000737:chemistry; D008081:Liposomes; D016716:PC12 Cells; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014162:Transfection / Q000379:methods*
chemical_list: D004337:Drug Carriers; D007202:Indicators and Reagents; D008055:Lipids; C086724:Lipofectamine; D008081:Liposomes; D010455:Peptides; D010714:Phosphatidylethanolamines; C066951:GALA peptide; C020888:1,2-dielaidoylphosphatidylethanolamine