Studies on the Internalization Mechanism of Cationic Cell-penetrating Peptides

• Published in: The Journal of biological chemistry Vol. 278; no. 33; pp. 31192 - 31201
• Main Authors: Drin, Guillaume, Cottin, Sylvine, Blanc, Emmanuelle, Rees, Anthony R., Temsamani, Jamal
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15-08-2003; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Antennapedia Homeodomain Protein; Antineoplastic Agents - pharmacology; Antineoplastic Agents, Phytogenic - pharmacology; Cations - metabolism; Cell Membrane - metabolism; Endocytosis - drug effects; Endocytosis - physiology; Enzyme Inhibitors - pharmacology; Ethylmaleimide - pharmacology; Fixatives - pharmacology; Homeodomain Proteins - chemistry; Homeodomain Proteins - metabolism; Humans; Hydrogen-Ion Concentration; K562 Cells; Lipid Bilayers - metabolism; Molecular Sequence Data; Nocodazole - pharmacology; Nuclear Proteins; Oligopeptides - physiology; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Temperature; Transcription Factors; Vinblastine - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M303938200

A great deal of data has been amassed suggesting that cationic peptides are able to translocate into eucaryotic cells in a temperature-independent manner. Although such peptides are widely used to promote the intracellular delivery of bioactive molecules, the mechanism by which this cell-penetrating activity occurs still remains unclear. Here, we present an in vitro study of the cellular uptake of peptides, originally deriving from protegrin (the SynB peptide vectors), that have also been shown to enhance the transport of drugs across the blood-brain barrier. In parallel, we have examined the internalization process of two lipid-interacting peptides, SynB5 and pAntp-(43–58), the latter corresponding to the translocating segment of the Antennapedia homeodomain. We report a quantitative study of the time- and dose-dependence of internalization and demonstrate that these peptides accumulate inside vesicular structures. Furthermore, we have examined the role of endocytotic pathways in this process using a variety of metabolic and endocytosis inhibitors. We show that the internalization of these peptides is a temperature- and energy-dependent process and that endosomal transport is a key component of the mechanism. Altogether, our results suggest that SynB and pAntp-(43–58) peptides penetrate into cells by an adsorptive-mediated endocytosis process rather than temperature-independent translocation.