Cell entry of arginine-rich peptides is independent of endocytosis

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Item Type:	Article
Title:	Cell entry of arginine-rich peptides is independent of endocytosis
Creators Name:	Ter-Avetisyan, G., Tünnemann, G., Nowak, D., Nitschke, M., Herrmann, A., Drab, M. and Cardoso, M.C.
Abstract:	Arginine-rich peptides are a subclass of cell-penetrating peptides that are taken up by living cells and can be detected freely diffusing inside the cytoplasm and nucleoplasm. This phenomenon has been attributed to either an endocytic mode of uptake and a subsequent release from vesicles or to direct membrane penetration (transduction). To distinguish between both possibilities we have blocked endocytic pathways suggested to be involved in uptake of cell penetrating peptides and monitored by confocal microscopy the uptake and distribution of the cell-penetrating TAT peptide into living mammalian cells over time. To prevent side effects of chemical inhibitors, we used genetically engineered cells as well as different temperature. We found that a knock down of clathrin-mediated endocytosis and a knockout of caveolin-mediated endocytosis did not affect the ability of TAT to enter cells. In addition, the TAT peptide showed the same intracellular distribution throughout the cytoplasm and nucleus as in control cells. Even incubation of cells at 4(o)C did neither abrogate TAT uptake nor change its intracellular distribution. We therefore conclude that this distribution results from TAT peptide that directly penetrated (transduced) the plasma membrane. The formation of non selective pores is unlikely, since simultaneously added fluorophores were not taken up together with the TAT peptide. In summary, although the frequency and kinetics of TAT transduction varied between cell types, it was independent of endocytosis.
Keywords:	3T3 Cells, Cell Nucleus Active Transport, Arginine, Caveolins, Cell Membrane, Cell Nucleus, Clathrin, Cricetinae, Cytoplasm, Endocytosis, tat Gene Products, Knockout Mice, Peptides, Animals, Mice
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	284
Number:	6
Page Range:	3370-3378
Date:	6 February 2009
Official Publication:	https://doi.org/10.1074/jbc.M805550200
PubMed:	View item in PubMed

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