Cell-penetrating peptides uptake

Lundberg, P. and Langel, U. (2006). Uptake mechanisms of cell-penetrating peptides derived from the Alzheimer s disease associated gamma-secretase complex. Int. J. Pept. Res. Therap. 12, 105-114. 

Richard JP, et al. Cell-penetrating peptides - a reevaluation of the mechanism of cellular uptake. J Biol Chem 2003 278 585. 

Marty C, Meylan C, Schott H, et al. Enhanced heparan sulfate proteoglycan-mediated uptake of cell-penetrating peptide-modified liposomes. Cell Mol Life Sci 2004 61 (14) 1785-1794. 

Duchardt, F., Fotin-Mleczek, M., Schwarz, H., Fischer, R., Brock, R. A comprehensive model for the cellular uptake of cationic cell-penetrating peptides. Traffic 2007, 8, 848-66. 

Lundin P, Johansson H, Guterstam P, Holm T, Hansen M, Langel U, EL Andaloussi S (2008) Distinct uptake routes of cell-penetrating peptide conjugates. Bioconjug Chem 19 2535-2542... 

Already in 1965, Ryser and Hancock provided evidence that histones and polyamino acids could greatly enhance albumin uptake by cultured tumor cells (6). More recently, several polybasic peptides (so-called protein transduction domains, PTDs or cell-penetrating peptides, CPPs) have been shown to efficiently mediate uptake of nucleic acids, bioactive peptides, phage particles, and liposomes into a wide variety of mammalian cells. The initially proposed ability of CPPs to penetrate plasma membranes via a temperature-independent, non-endocytotic pathway was later shown to be a fixation artifact, and it is currently widely accepted that CPP-mediated macromolecular delivery follows energy-dependent endocytotic pathways that in most cases depend on the expression of cell-surface heparan sulfate proteoglycans (HSPGs) (7). 

New strategies for the delivery of biomolecules have emerged with the discovery of cell penetrating peptides (CPP), which are small, generally basic amino acid-rich peptides that are internalized within most cell types. More importantly, they allow the cellular uptake of chemically conjugated biomolecules of various types, including ON, peptides or proteins (7,8). 

Abes, S., Richard, J. P., Thierry, A. R., Clair, P., and Lebleu, B. (2007) Tat-Derived Cell-Penetrating Peptides Discovery, Mechanism of Cell Uptake, and Applications to the Delivery of Oligonucleotides. Handbook of Cell-Penetrating Peptides (second edition). 29-42. 

Richard, J. P., Melikov, K., Vives, E., Ramos, C., Verbeure, B., Gait, M. J., Cher-nomordik, L. V., and Lebleu, B. (2003) Cell-penetrating peptides. A reevaluation of the mechanism of cellular uptake. JBiol Chem. 278,585-590. 

The control of inverse transition temperatures by sequence manipulation and biocompatibility of ELPs make them useful polymers for drug delivery. Cultured cancer cells and solid tumors in animal models uptake fluorescently labeled ELPs in a thermally responsive manner (48,49). Two major limitations in cancer therapy have been the inability of therapeutic molecules to cross the cell membrane and the target-specificity of the compounds. To overcome these limitations cell-penetrating, peptides (CPP) have been fused with ELPs (CPP-ELP) to develop thermally responsive therapeutics with the ability to translocate the cell membrane (Figure 3B). CPPs can assist in the transportation of hydrophilic compounds (small molecules, oglionucleotides and peptides) across the cell membrane (50). Fusing ELPs to a variety of CPPs have revealed that the peptide sequence of penetratin demonstrates the most efficient cellular uptake (51). Further, these CPP-ELPs have been fused to a c-Myc inhibitory peptide known to target and inhibit cancer. As proof of principle, these fusion proteins inhibits proliferation of cultured cancer cell lines in a thermally responsive manner (52). 

Cl. Astriab-Fisher A, Sergueev D, Fisher M, et al. (2002). Conjugates of antisense oligonucleotides with the Tat and antennapedia cell-penetrating peptides Effects on cellular uptake, binding to target sequences, and biologic actions. Pharmaceut. Res. 19 744-754. 

Figure 7.7-3. Cell penetrating peptides, CPPs. Suggested uptake mechanisms for CPPs and examples of delivered cargoes. (A) CPP and peptide in single amino acid chain. (B) Oligo-deoxynucleotides either in complex or covalently linked. (C) Plasmid in complex by electrostatic interaction. (D) Protein either as fusion protein or in complex with CPP. (E) siRNA, covalently linked or as complex. (With permission from Ref. 54.)...

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