title: Cationic cell-penetrating peptides interfere with TNF signalling by induction of TNF receptor internalization.
abstract: Cationic cell-penetrating peptides (CPPs) have been used widely as delivery vectors for the import of molecules that otherwise do not cross the plasma membrane of eukaryotic cells. In this work, we demonstrate that the three cationic CPPs, Antennapedia homeodomain-derived peptide (Antp), nona-arginine and Tat-derived peptide, inhibit tumour necrosis factor (TNF)-mediated signal transduction. This inhibition is based on the downregulation of TNF receptors at the cell surface by induction of internalization. In contrast to TNF-dependent receptor internalization, no receptor activation occurs. The receptor downregulation is not restricted to the CPPs. Remarkably, the HIV-1 Tat protein itself also induces the internalization of TNF receptors. The dynamin dependence of the internalization, as well as the fact that epidermal growth factor receptors are also internalized, suggest a general induction of clathrin-dependent endocytosis as the mechanism of action. The significance of these findings for the use of cationic CPPs in the import of bioactive peptides is demonstrated here using a conjugate consisting of Antp and a Smac protein-derived cargo peptide. The cargo alone, when introduced into cells by electroporation, enhanced TNF-induced apoptosis by inhibiting the anti-apoptotic action of IAPs (inhibitor of apoptosis proteins). For the Antp-Smac conjugate at concentrations below 40 muM the inhibitory effect of the Antp peptide compensated for the pro-apoptotic activity of the cargo, and led to the protection of cells against TNF-mediated apoptosis. These data provide important new information for the use of cationic CPPs for the cellular delivery of bioactive molecules.
authors.affiliation: Department of Molecular Biology, Institute for Cell Biology, University of Tübingen, Auf der Morgenstelle 15, Tübingen, 72076, Germany.
authors.forename: Mariola
authors.initials: M
authors.lastname: Fotin-Mleczek
authors.forename: Stefan
authors.initials: S
authors.lastname: Welte
authors.forename: Oliver
authors.initials: O
authors.lastname: Mader
authors.forename: Falk
authors.initials: F
authors.lastname: Duchardt
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Hufnagel
authors.forename: Peter
authors.initials: P
authors.lastname: Scheurich
authors.forename: Roland
authors.initials: R
authors.lastname: Brock
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002412:Cations / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D015696:Gene Products, tat / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects* / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000187:drug effects / Q000378:metabolism; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D051996:Transcription Factor RelA / Q000037:antagonists & inhibitors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D061945:Caspase Inhibitors; D002412:Cations; D015696:Gene Products, tat; D010446:Peptide Fragments; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases