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See detailInsight into the cellular uptake mechanism of a secondary amphipathic cell penetrating peptide for siRNA delivery.
Konate, K.; Crombez, L.; Deshayes, S. et al

in Biochemistry (2010)

Delivery of siRNA remains a major limitation to their clinical application and several technologies have been proposed to improve their cellular uptake. We recently described a peptide-based nanoparticle ... [more ▼]

Delivery of siRNA remains a major limitation to their clinical application and several technologies have been proposed to improve their cellular uptake. We recently described a peptide-based nanoparticle system for efficient delivery of siRNA into primary cell lines: CADY. CADY is a secondary amphipathic peptide that forms stable complexes with siRNA and improves their cellular uptake independently of the endosomal pathway. In the present work, we have combined molecular modelling, spectroscopy and membrane interaction approaches, in order to gain further insight into CADY/siRNA particle mechanism of interaction with biological membrane. We demonstrate that CADY forms stable complexes with siRNA and binds phospholipids tightly, mainly through electrostatic interactions. Binding to siRNA or phospholipids triggers a conformational transition of CADY from an unfolded state to an -helical structure, thereby stabilizing CADY/siRNA complexes and improving their interactions with cell membranes. Therefore, we propose that CADY cellular membrane interaction is driven by its structural polymorphism which enables stabilization of both electrostatic and hydrophobic contacts with surface membrane proteoglycan and phospholipids. [less ▲]

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See detailA New Potent Secondary Amphipathic Cell-Penetrating Peptide For Sirna Delivery Into Mammalian Cells
Crombez, L.; Aldrian-Herrada, G.; Konate, K. et al

in Molecular Therapy (2009), 17(1),

RNA interference constitutes a powerful tool for biological studies, but has also become one of the most challenging therapeutic strategies. However, small interfering RNA (siRNA)-based strategies suffer ... [more ▼]

RNA interference constitutes a powerful tool for biological studies, but has also become one of the most challenging therapeutic strategies. However, small interfering RNA (siRNA)-based strategies suffer from their poor delivery and biodistribution. Cell-penetrating peptides (CPPs) have been shown to improve the intracellular delivery of various biologically active molecules into living cells and have more recently been applied to siRNA delivery. To improve cellular uptake of siRNA into challenging cell lines, we have designed a secondary amphipathic peptide (CADY) of 20 residues combining aromatic tryptophan and cationic arginine residues. CADY adopts a helical conformation within cell membranes, thereby exposing charged residues on one side, and Trp groups that favor cellular uptake on the other. We show that CADY forms stable complexes with siRNA, thereby increasing their stability and improving their delivery into a wide variety of cell lines, including suspension and primary cell lines. CADY-mediated delivery of subnanomolar concentrations of siRNA leads to significant knockdown of the target gene at both the mRNA and protein levels. Moreover, we demonstrate that CADY is not toxic and enters cells through a mechanism which is independent of the major endosomal pathway. Given its biological properties, we propose that CADY-based technology will have a significant effect on the development of fundamental and therapeutic siRNA-based applications. [less ▲]

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See detailNew Basic Membrane-Destabilizing Peptides For Plasmid-Based Gene Delivery In Vitro And In Vivo
Rittner, K.; Benavente, A.; Bompard-Sorlet, A. et al

in Molecular Therapy (2002), 5(2), 104-14

We have designed new basic amphiphilic peptides, ppTG1 and ppTG20 (20 amino acids), and evaluated their efficiencies in vitro and in vivo as single-component gene transfer vectors. ppTG1 and ppTG20 bind ... [more ▼]

We have designed new basic amphiphilic peptides, ppTG1 and ppTG20 (20 amino acids), and evaluated their efficiencies in vitro and in vivo as single-component gene transfer vectors. ppTG1 and ppTG20 bind to nucleic acids and destabilize liposomes consisting of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and cholesterol (3:1 mol/mol) at pH 5 and pH 7. Complexes of plasmid DNA and ppTG1 gave rise to efficient transfection in a variety of human and murine cell lines at low charge ratios ([+/-] between 1 and 2). In cell culture experiments, such vectors were superior to the membrane-destabilizing peptide KALA. In comparison with cationic lipid-, dendrimer-, and polymer-based transfection agents like Superfect, polyethylenimine (PEI), and Lipofectin, ppTG1 vectors showed good transfection efficiencies, especially at low DNA doses. Moreover, we demonstrated for the first time successful gene transfer in living animals with a single-component peptide vector. In the mouse, intravenous injection of a luciferase expression plasmid complexed with ppTG1 or ppTG20 led to significant gene expression in the lung 24 hours after injection. Structure-function studies with ppTG1, ppTG20, and sequence variants suggest that the high gene transfer activity of these peptides is correlated with their propensity to exist in alpha-helical conformation, which seems to be strongly influenced by the nature of the hydrophobic amino acids. [less ▲]

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