Mapping of Protein Transduction Pathways with Fluorescent Microscopy

  • Helin RäägelEmail author
  • Pille Säälik
  • Ülo Langel
  • Margus Pooga
Part of the Methods in Molecular Biology book series (MIMB, volume 683)


The number of various cargo delivered into cells by CPPs demonstrates the effective transport abilities of these short-peptidic sequences. Over the years of research, the translocation process of CPP–cargo complexes has been mapped to being of mostly endocytic nature, however, there is still no consensus on which of the endocytic routes is prevalent and to which extent the interplay between different modes of endocytosis is taking place. The intracellular trafficking of CPPs attached to a cargo molecule is even less understood. Therefore, the internalization and the subsequent intracellular targeting of complexes need clarification in order to define cellular destinations and improve the targeting of the cargo molecule to specific cellular compartments depending on the cargo attached to the transporting vector. This chapter focuses on describing the methods for visualizing the CPP–protein complexes in relation to different endocytic markers, for example transferrin (marker for clathrin-mediated endocytosis) and cholera toxin (ambiguous marker for clathrin-, caveolin-, and flotillin-mediated, but also clathrin- and caveolin-independent endocytosis) to determine the role of the respective pathways during entry to cells, and to different intracellular targets, for instance the lysosomal organelles or the Golgi apparatus. Additionally, antibody staining of respective endocytic vesicles following the internalization of CPP–protein complexes will be discussed.

Key words

Cell-penetrating peptide Fluorescence microscopy Protein transduction Endocytosis Intracellular trafficking 



The work was supported by grants from Estonian Science Foundation (ESF 7058), Estonian Ministry of Education and Research (0182691s05), Swedish Research Council (VR-NT); Center for Biomembrane Research, Stockholm; and Knut and Alice Wallenberg’s Foundation.


  1. 1.
    Schwarze S. R., Ho A., Vocero-Akbani A., Dowdy S. F. (1999) In vivo protein transduction: delivery of a biologically active protein into the mouse. Science. 285(5433), 1569–1572.CrossRefPubMedGoogle Scholar
  2. 2.
    El-Andaloussi S., Johansson H. J., Lundberg P., Langel Ü. (2006) Induction of splice correction by cell-penetrating peptide nucleic acids. J Gene Med. 8(10), 1262–1273.CrossRefPubMedGoogle Scholar
  3. 3.
    Gitton Y., Tibaldi L., Dupont E., Levi G., Joliot A. (2009) Efficient CPP-mediated Cre protein delivery to developing and adult CNS tissues. BMC Biotechnol. 9, 40.CrossRefPubMedGoogle Scholar
  4. 4.
    Console S., Marty C., Garcia-Echeverria C., Schwendener R., Ballmer-Hofer K. (2003) Antennapedia and HIV transactivator of transcription (TAT) “protein transduction domains” promote endocytosis of high molecular weight cargo upon binding to cell surface glycosaminoglycans. J Biol Chem. 278(37), 35109–35114.CrossRefPubMedGoogle Scholar
  5. 5.
    Rinne J., Albarran B., Jylhävä J., Ihalainen T. O., Kankaanpää P., Hytönen V. P., Stayton P. S., Kulomaa M. S., Vihinen-Ranta M. (2007) Internalization of novel non-viral vector TAT-streptavidin into human cells. BMC Biotechnol. 7, 1.CrossRefPubMedGoogle Scholar
  6. 6.
    Säälik P., Padari K., Niinep A., Lorents A., Hansen M., Jokitalo E., Langel Ü., Pooga M. (2009) Protein delivery with transportans is mediated by caveolae rather than flotillin-dependent pathways. Bioconjug Chem. 20(5), 877–887.CrossRefPubMedGoogle Scholar
  7. 7.
    Wadia J. S., Stan R. V., Dowdy S. F. (2004) Transducible TAT-HA fusogenic peptide enhances escape of TAT-fusion proteins after lipid raft macropinocytosis. Nat Med. 10(3), 310–315.CrossRefPubMedGoogle Scholar
  8. 8.
    Tünnemann G., Martin R. M., Haupt S., Patsch C., Edenhofer F., Cardoso M. C. (2006) Cargo-dependent mode of uptake and bioavailability of TAT-containing proteins and peptides in living cells. Faseb J. 20(11), 1775–1784.CrossRefPubMedGoogle Scholar
  9. 9.
    Duchardt F., Fotin-Mleczek M., Schwarz H., Fischer R., Brock R. (2007) A comprehensive model for the cellular uptake of cationic cell-penetrating peptides. Traffic. 8(7), 848–866.CrossRefPubMedGoogle Scholar
  10. 10.
    Räägel H., Säälik P., Hansen M., Langel Ü., Pooga M. (2009) CPP-protein constructs induce a population of non-acidic vesicles during trafficking through endo-lysosomal pathway. J Control Release. 139(2), 108–117.CrossRefPubMedGoogle Scholar
  11. 11.
    Padari K., Säälik P., Hansen M., Koppel K., Raid R., Langel Ü., Pooga M. (2005) Cell transduction pathways of transportans. Bioconjug Chem. 16(6), 1399–1410.CrossRefPubMedGoogle Scholar
  12. 12.
    Bidwell G. L. 3 rd, Davis A. N., Raucher D. (2009) Targeting a c-Myc inhibitory polypeptide to specific intracellular compartments using cell penetrating peptides. J Control Release. 135(1), 2–10.CrossRefPubMedGoogle Scholar
  13. 13.
    Hamilton A. J., Baulcombe D. C. (1999) A species of small antisense RNA in posttranscriptional gene silencing in plants. Science. 286(5441), 950–952.CrossRefPubMedGoogle Scholar
  14. 14.
    Misaki R., Nakagawa T., Fukuda M., Taniguchi N., Taguchi T. (2007) Spatial segregation of degradation- and recycling-trafficking pathways in COS-1 cells. Biochem Biophys Res Commun. 360(3), 580–585.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Helin Räägel
    • 1
    Email author
  • Pille Säälik
    • 2
  • Ülo Langel
    • 1
    • 3
  • Margus Pooga
    • 1
  1. 1.Institute of Molecular and Cell BiologyUniversity of TartuTartuEstonia
  2. 2.Institute of Molecular and Cell BiologyUniversity of TartuTartuEstonia
  3. 3.Laboratory of Molecular Biotechnology, Institute of TechnologyTartu UniversityTartuEstonia

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