Cytosolic Targeting of Macromolecules Using a pH-Dependent Fusogenic Peptide in Combination with Cationic Liposomes

Abstract

pH-Sensitive peptides and polymers have been employed as additives to enhance the cytosolic delivery of drugs and genes by facilitating their endosomal escape. However, little attention has been paid to the intracellular fate of these peptides and polymers. In this study, we explored the possibility of utilizing GALA, a pH-sensitive fusogenic peptide, as a cytosol-targeting vehicle. In combination with cationic liposomes, Lipofectamine 2000 (LF2000), the feasibility of this approach for the cytosolic targeting of proteins and nanoparticles was exemplified through the delivery of avidin (68 kDa) and streptavidin-coated quantum dots (15-20 nm) in serum-containing medium. The use of cationic liposomes is critical to enhance the cell-surface adhesion of the GALA conjugates and eventual endosomal uptake. Circular dichroism studies suggest that the GALA can be liberated from cationic liposomes at a reducing pH to form a helical structure and this may eventually lead to disruption of the endosomal membrane to achieve an efficient leakage of the GALA conjugates into the cytosol.

Cell-Penetrating Peptide-Functionized Quantum Dots for Intracellular Delivery

“…After endocytic uptake, the internalized arginine-rich CPPs, either alone or linked to cargoes, must escape from the endocytic vesicles into the cytosol to avoid degradation,54, 75 although arginine-rich CPPs and cargoes have been reported to be able to reach the cell nucleus 47, 50, 76, 77. Several strategies have been proposed to overcome endosomal entrapment, including incorporation of the lysosomotropic agent chloroquine22 or as endosome disruptive peptides, such as HA2 peptide,39, 78, 79 INF7 peptide,75 deca-histidine,80 GALA peptide,81 and Pas peptide, into the transport complex 82…”

Improving cell-based therapies by nanomodification

“…One approach is to coat particles with membrane structures (polymer) that are able to fuse with endosomal membrane to improve the release of exogenous materials from endosomes or lysosomes [85]. Besides, nanomaterials can also be modified with pH-responsive biomolecules such as a glutamic acid-rich peptide, which can change the structure from random to helical form to promote its interaction with endosomal membranes, inducing membrane disruption and leakage of contents [86, 87]. After being released from the vesicle compartments, the nanomaterials will spontaneously interact with their intracellular targets such as various organelles or nucleus (Fig.…”

Engineered nanomaterial uptake and tissue distribution: from cell to organism

“…[95][96][97] Similar effects can be induced using pH-sensitive fusiogenic peptides (eg, amphiphilic peptides with repetitive GALA sequences) in combination with cationic liposomes. 98 Other ENMs (eg, certain types of carbon nanotubes) penetrate the vesicle (or cell) membrane directly and enter the cytosol. 99 Once in the cytosol, ENMs may induce the production of reactive oxygen species and inflict oxidative stress.…”