octaarginine and 1-pyrenebutyrate

Significant progress has been made in the development of chemical biology methods used to study the molecular behavior and interplay among live cells. These include the development of novel fluorescent molecules and photo-cross-linking agents that can be used to determine the cellular locations of biomacromolecules (including proteins and nucleic acids). Various biosensors utilizing the remarkable ligand-recognition abilities of biomacromolecules have also been developed. To allow such chemically functionalized molecules to interact with their partners, and to fully exploit the abilities and functions thereof, it is necessary to efficiently deliver such molecules into cells, specifically into the cytosol. Here, we illustrate intracellular delivery methods employing arginine-rich cell-penetrating peptides (CPPs) (e.g., octa-arginine) in the presence of a counteranion, pyrenebutyrate. This approach is especially suitable for intracellular delivery of small proteins and peptides. Approaches employing arginine-rich CPPs tagged with a penetration-accelerating sequence can also be used toward this end.

Topics: Amino Acid Sequence; Animals; Cell Membrane Permeability; Cell-Penetrating Peptides; Cytosol; Drug Carriers; Endocytosis; Green Fluorescent Proteins; Humans; Luminescent Agents; Molecular Sequence Data; Oligopeptides; Pyrenes; Recombinant Fusion Proteins

Arginine-rich cell-penetrating peptides, including octaarginine (R8) and HIV-1 TAT peptides, have the ability to translocate through cell membranes and transport exogenous bioactive molecules into cells. Hydrophobic counteranions such as pyrenebutyrate (PyB) have been reported to markedly promote the membrane translocation of these peptides. In this study, using model membranes having liquid-ordered (Lo) and liquid-disordered (Ld) phases, we explored the effects of PyB on the promotion of R8 translocation. Confocal microscopic observations of giant unilamellar vesicles (GUVs) showed that PyB significantly accelerated the accumulation of R8 on membranes containing negatively charged lipids, leading to the internalization of R8 without collapse of the GUV structures. PyB displayed an alternative activity, increasing the fluidity of the negatively charged membranes, which diminished the distinct Lo/Ld phase separation on GUVs. This was supported by the decrease in fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH). Additionally, PyB induced membrane curvature, which has been suggested as a possible mechanism of membrane translocation for R8. Taken together, our results indicate that PyB may have multiple effects that promote R8 translocation through cell membranes.

Topics: Animals; Cell-Penetrating Peptides; Diphenylhexatriene; Fluorescence Polarization; Fluorescent Dyes; Hydrophobic and Hydrophilic Interactions; Membrane Fluidity; Microscopy, Confocal; Oligopeptides; Phosphatidylcholines; Protein Transport; Pyrenes; Static Electricity; Swine; Unilamellar Liposomes