Cell-penetrating peptide secures an efficient endosomal escape of an intact cargo upon a brief photo-induction

• Published in: Cellular and molecular life sciences : CMLS 2013-12, Vol.70 (24), p.4825-4839
• Main Authors: Räägel, Helin, Hein, Margot, Kriiska, Asko, Säälik, Pille, Florén, Anders, Langel, Ülo, Pooga, Margus
• Format: Article
• Language: English
• Subjects: Animals; bioactive properties; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cell Biology; Cell-Penetrating Peptides - metabolism; Cellular biology; CHO Cells; CPP; Cricetinae; Cricetulus; Degradation; Drug Carriers - metabolism; Drug Delivery Systems; Effective delivery; Endosomal release; endosomes; Endosomes - metabolism; Fluorescent Dyes; Galanin - metabolism; Life Sciences; microtubules; Peptides; Photo-induction; Photochemical Processes; physiological transport; Protein transduction domain; Protein Transport; PTD; Recombinant Fusion Proteins - metabolism; Research Article; Signal transduction; Stability; tubulin; Tubulin - administration & dosage; Tubulin - metabolism; Wasp Venoms - metabolism
• ISSN: 1420-682X; 1420-9071; 1420-9071
• DOI: 10.1007/s00018-013-1416-z

Since their discovery, cell-penetrating peptides (CPPs) have provided a novel, efficient, and non-invasive mode of transport for various (bioactive) cargos into cells. Despite the ever-growing number of successful implications of the CPP-mediated delivery, issues concerning their intracellular trafficking, significant targeting to degradative organelles, and limited endosomal escape are still hindering their widespread use. To overcome these obstacles, we have utilized a potent photo-induction technique with a fluorescently labeled protein cargo attached to an efficient CPP, TP10. In this study we have determined some key requirements behind this induced escape (e.g., dependence on peptide-to-cargo ratio, time and cargo), and have semi-quantitatively assessed the characteristics of the endosomes that become leaky upon this treatment. Furthermore, we provide evidence that the photo-released cargo remains intact and functional. Altogether, we can conclude that the photo-induced endosomes are specific large complexes-condensed non-acidic vesicles, where the released cargo remains in its native intact form. The latter was confirmed with tubulin as the cargo, which upon photo-induction was incorporated into microtubules. Because of this, we propose that combining the CPP-mediated delivery with photo-activation technique could provide a simple method for overcoming major limitations faced today and serve as a basis for enhanced delivery efficiency and a subsequent elevated cellular response of different bioactive cargo molecules.