title: Scavenger receptor-mediated uptake of cell-penetrating peptide nanocomplexes with oligonucleotides.
abstract: Cell-penetrating peptides (CPPs) are short cationic peptides that penetrate cells by interacting with the negatively charged plasma membrane; however, the detailed uptake mechanism is not clear. In contrary to the conventional mode of action of CPPs, we show here that a CPP, PepFect14 (PF14), forms negatively charged nanocomplexes with oligonucleotides and their uptake is mediated by class-A scavenger receptors (SCARAs). Specific inhibitory ligands of SCARAs, such as fucoidin, polyinosinic acid, and dextran sulfate, totally inhibit the activity of PF14-oligonucleotide nanocomplexes in the HeLa pLuc705 splice-correction cell model, while nonspecific, chemically related molecules do not. Furthermore, RNA interference (RNAi) knockdown of SCARA subtypes (SCARA3 and SCARA5) that are expressed in this cell line led to a significant reduction of the activity to <50%. In line with this, immunostaining shows prevalent colocalization of the nanocomplexes with the receptors, and electron microscopy images show no binding or internalization of the nanocomplexes in the presence of the inhibitory ligands. Interestingly, naked oligonucleotides also colocalize with SCARAs when used at high concentrations. These results demonstrate the involvement of SCARA3 and SCARA5 in the uptake of PF14-oligonucleotide nanocomplexes and suggest for the first time that some CPP-based systems function through scavenger receptors, which could yield novel possibilities to understand and improve the transfection by CPPs.
authors.affiliation: Department of Neurochemistry, Stockholm University, 21A Svante Arrhenius vag, Stockholm 10691, Sweden. kariem@neurochem.su.se
authors.forename: Kariem
authors.initials: K
authors.lastname: Ezzat
authors.forename: Henrik
authors.initials: H
authors.lastname: Helmfors
authors.forename: Oana
authors.initials: O
authors.lastname: Tudoran
authors.forename: Carmen
authors.initials: C
authors.lastname: Juks
authors.forename: Staffan
authors.initials: S
authors.lastname: Lindberg
authors.forename: Kärt
authors.initials: K
authors.lastname: Padari
authors.forename: Samir
authors.initials: S
authors.lastname: El-Andaloussi
authors.forename: Margus
authors.initials: M
authors.lastname: Pooga
authors.forename: Ulo
authors.initials: U
authors.lastname: Langel
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D057846:Cell-Penetrating Peptides / Q000378:metabolism* / Q000493:pharmacokinetics; D016264:Dextran Sulfate / Q000494:pharmacology; D060748:Fetuins / Q000494:pharmacology; D015870:Gene Expression; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D055666:Lipopeptides / Q000378:metabolism* / Q000493:pharmacokinetics; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000648:ultrastructure; D009841:Oligonucleotides / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051117:Scavenger Receptors, Class A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D057846:Cell-Penetrating Peptides; D060748:Fetuins; D006360:Heat-Shock Proteins; D055666:Lipopeptides; D009841:Oligonucleotides; C560878:PepFect14 peptide; C112525:SCARA3 protein, human; C569833:SCARA5 protein, human; D051117:Scavenger Receptors, Class A; D016264:Dextran Sulfate