Uptake of analogs of penetratin, Tat(48-60) and oligoarginine in live cells.
Cell-penetrating peptides are regarded as promising vectors for intracellular delivery of large, hydrophilic molecules, but their mechanism of uptake is poorly understood. Since it has now been demonstrated that the use of cell fixation leads to artifacts in microscopy studies on the cellular uptake of such peptides, much of what has been considered as established facts must be reinvestigated using live (unfixed) cells. In this work, the uptake of analogs of penetratin, Tat(48-60), and heptaarginine in two different cell lines was studied by confocal laser scanning microscopy. For penetratin, an apparently endocytotic uptake was observed, in disagreement with previous studies on fixed cells found in the literature. Substitution of the two tryptophan residues, earlier reported to be essential for cellular uptake, did not alter the uptake characteristics. A heptaarginine peptide, with a tryptophan residue added in the C-terminus, was found to be internalized by cells via an energy-independent, non-endocytotic pathway. Finally, a crucial role for arginine residues in penetratin and Tat(48-60) was demonstrated.
Thorén
Per E G
PE
Department of Chemistry and Bioscience, Chalmers University of Technology, Kemivägen 10, SE-412 96, Gothenburg, Sweden. thoren@phc.chalmers.se
Persson
Daniel
D
Isakson
Petter
P
Goksör
Mattias
M
Onfelt
Agneta
A
Nordén
Bengt
B
D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D057846:Cell-Penetrating Peptides; D006224:Cricetinae; D005456:Fluorescent Dyes / Q000378:metabolism; D015696:Gene Products, tat / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D054322:tat Gene Products, Human Immunodeficiency Virus
D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D005456:Fluorescent Dyes; D015696:Gene Products, tat; D009842:Oligopeptides; D010446:Peptide Fragments; C416678:heptaarginine amide; D054322:tat Gene Products, Human Immunodeficiency Virus; C422951:tat peptide (48-60), Human immunodeficiency virus 1; C414409:penetratin