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Endocytic Uptake (endocytic + uptake)

Distribution by Scientific Domains
Chemistry75%

Selected Abstracts

Endocytic uptake of fluorescence labelled DNA in yeast

JOURNAL OF BASIC MICROBIOLOGY, Issue 1 2010
Sean-Patrick Riechers
Abstract After dispiriting results using viral vectors in gene therapy, by which a number of patients acquired cancer as a result of the use of retroviral vector constructs, the percentage of non-viral approaches has increased over recent years. To elucidate potential bottlenecks in the non-viral transfection process we here introduce a novel method to directly visualize endocytic non-viral DNA uptake in a transfection approach. This novel method allows for the first time to monitor the location of DNA which is taken up by endocytosis in yeast (Saccharomyces cerevisiae) wild type and mutant strains. More specifically it enables drawing conclusions about conditions favouring non-viral gene transfection. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Investigation of penetratin peptides.

JOURNAL OF PEPTIDE SCIENCE, Issue 12 2005
Part 2.
Abstract As endocytic uptake of the Antennapedia homeodomain-derived penetratin peptide (RQIKIWFQNRRMKWKK) is finally being revealed, some of the early views about penetratin need to be reconsidered. Endocytic uptake seems to contradict the indispensability of tryptophans and also the minimum length of 16 amino acid residues for efficient internalization. To revise the membrane translocation of penetratin, two penetratin analogs were designed and synthesized: a peptide in which tryptophans were replaced by phenylalanines (Phe6, 14 -penetratin, RQIKIFFQNRRMKFKK) and a shortened analog (dodeca-penetratin, RQIKIWF-R-KWKK) made up of only 12 residues. The peptides were fluorescently labeled and applied to live, unfixed cells from various lines. Cellular uptake was analysed by confocal microscopy and flow cytometry. Low temperature or ATP-depletion blocked the intracellular entry of all three penetratin peptides. A decrease in membrane fluidity or cholesterol depletion with methyl-,-cyclodextrin greatly inhibited peptide uptake, showing the involvement of cholesterol-rich lipid rafts in internalization. Exogenous heparan sulfate also diminished the internalization of penetratin and its derivatives, reflecting the paramount importance of electrostatic interactions with polyanionic cell-surface proteoglycans. The beneficial presence of tryptophans is supported by observations on the decreased cellular uptake of Phe6, 14 -penetratin. The maintained translocational efficiency of dodeca-penetratin demonstrates that a thorough understanding of penetratin internalization can yield new penetratin analogs with unaltered translocational abilities. This study provides evidence on the energy-dependent and lipid raft-mediated endocytic uptake of penetratin and highlights the necessity of revealing those pathways that cationic cell-penetrating peptides employ to enter live cells. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source]

HeLa Cell Entry by Guanidinium-Rich ,-Peptides: Importance of Specific Cation,Cell Surface Interactions

CHEMBIOCHEM, Issue 8 2007
Terra B. Potocky
Abstract Short cationic oligomers, including arginine-rich peptides and analogous ,-amino acid oligomers (", -peptides"), can enter the cytoplasm and nucleus of a living cell from the extracellular medium. It seems increasingly clear that multiple entry pathways are possible, depending upon the structure of the guanidinium-rich molecule, the type of cell, and other factors. We have previously shown that conformational stability and spatial clustering of guanidinium groups increase the HeLa cell entry efficiency of short helical , -peptides bearing six guanidinium groups, results that suggest that these , -peptides could be useful tools for studying the entry process. Here we describe studies intended to identify the point in the entry process at which helix stability and spatial arrangement of guanidinium groups exert their effect. Our results suggest that key distinctions involve the mode of interaction between different guanidinium-rich ,-peptides and the HeLa cell surface. A specific guanidinium display appears to be required for proper engagement of cell-surface heparan sulfate proteoglycans and concomitant induction of endocytic uptake. [source]