| 1. |
- Juks, Carmen, et al.
(author)
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Cell-penetrating peptides recruit type A scavenger receptors to the plasma membrane for cellular delivery of nucleic acids
- 2017
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In: The FASEB Journal. - 0892-6638 .- 1530-6860. ; 31:3, s. 975-988
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Journal article (peer-reviewed)abstract
- Scavenger receptors (SRs) are a large family of multifunctional receptors that are involved in a range of physiologic and pathologic processes. The ability of class A scavenger receptors (SR-As) to bind anionic ligands facilitates the internalization of negatively charged cell-penetrating peptide (CPP)-nucleic acid nanocomplexes and thus makes them attractive targets for delivery of various nucleic acids. Recently, we demonstrated that SR-A3 and SR-A5 are recruited from intracellular membranes to the plasma membrane after incubation with PepFect 14-splice-switching oligonucleotide complexes. Here, we examined the mechanisms responsible for translocation of SR-As to the cell surface. We demonstrate that, in addition to nanocomplexes, some amphipathic CPPs are able to induce externalization of SR-A3 and SR-A5, and this process requires the presence of calcium ions. Furthermore, translocation of SR-A3 and SR-A5 requires activity of phosphatidylinositol-3-kinase, intact actin cytoskeleton, and the presence of serum proteins in culture medium.
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| 2. |
- Lorents, Annely, et al.
(author)
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Arginine-Rich Cell-Penetrating Peptides Require Nucleolin and Cholesterol-Poor Subdomains for Translocation across Membranes
- 2018
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In: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 29:4, s. 1168-1177
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Journal article (peer-reviewed)abstract
- Proficient transport vectors called cell-penetrating peptides (CPPs) internalize into eukaryotic cells mostly via endocytic pathways and facilitate the uptake of various cargo molecules attached to them. However, some CPPs are able to induce disturbances in the plasma membrane and translocate through it seemingly in an energy-independent manner. For understanding this phenomenon, giant plasma membrane vesides (GPMVs) derived from the cells are a beneficial model system, since GPMVs have a complex membrane composition comparable to the cells yet lack cellular energy dependent mechanisms. We investigated the translocation of arginine-rich CPPs into GPMVs with different membrane compositions. Our results demonstrate that lower cholesterol content favors accumulation of nona-arginine and, additionally, sequestration of cholesterol increases the uptake of the CPPs in vesicles with higher cholesterol packing density. Furthermore, the proteins on the surface of vesicles are essential for the uptake of arginine-rich CPPs: downregulation of nudeolin decreases the accumulation and digestion of proteins on the membrane suppresses translocation even more efficiently.
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| 3. |
- Lorents, Annely, et al.
(author)
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Cell-penetrating Peptides Split into Two Groups Based on Modulation of Intracellular Calcium Concentration
- 2012
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:20, s. 16880-16889
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Journal article (peer-reviewed)abstract
- Cell-penetrating peptides (CPPs) promote the uptake of different cargo molecules, e.g. therapeutic compounds, making the harnessing of CPPs a promising strategy for drug design and delivery. However, the internalization mechanisms of CPPs are still under discussion, and it is not clear how cells compensate the disturbances induced by peptides in the plasma membrane. In this study, we demonstrate that the uptake of various CPPs enhances the intracellular Ca2+ levels in Jurkat and HeLa cells. The elevated Ca2+ concentration in turn triggers plasma membrane blebbing, lysosomal exocytosis, and membrane repair response. Our results indicate that CPPs split into two major classes: (i) amphipathic CPPs that modulate the plasma membrane integrity inducing influx of Ca2+ and activating downstream responses starting from low concentrations; (ii) non-amphipathic CPPs that do not evoke changes at relevant concentrations. Triggering of the membrane repair response may help cells to replace distorted plasma membrane regions and cells can recover from the influx of Ca2+ if its level is not drastically elevated.
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| 4. |
- Padari, Kart, et al.
(author)
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S4(13)-PV Cell-Penetrating Peptide Forms Nanoparticle-Like Structures to Gain Entry Into Cells
- 2010
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In: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 21:4, s. 774-783
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Journal article (peer-reviewed)abstract
- Despite increasing interest in cell-penetrating peptides (CPPs) as carriers for drugs and in gene therapy, the current understanding of their exact internalization mechanism is still far from complete. The cellular translocation of CPPs and their payloads has been mostly described by fluorescence- and activity-based methods, leaving the more detailed characterization at the ultrastructural level almost out of attention. Herein, we used transmission electron microscopy to characterize the membrane interaction and internalization of a cell-penetrating peptide S4(13)-PV. We demonstrate that S4(13)-PV peptide forms spherical nanoparticle-like regular structures upon association with cell surface glycosaminoglycans on the plasma membrane. Insertion of S4(13)-PV particles into plasma membrane induces disturbances and leads to the vesicular uptake of peptides by cells. We propose that for efficient cellular translocation S4(13)-PV peptides have to assemble into particles of specific size and shape. The spherical peptide particles are not dissociated in intracellular vesicles but often retain their organization and remain associated with the membrane of vesicles, destabilizing them and promoting the escape of peptides into cytosol. Lowering the temperature and inhibition of dynamins' activity reduce the internalization of S4(13)-PV peptides, but do not block it completely. Our results provide an ultrastructural insight into the interaction mode of CPPs with the plasma membrane and the distribution in cells, which might help to better understand how CPPs cross the biological membranes and gain access into cells.
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| 5. |
- Palm-Apergi, Caroline, et al.
(author)
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The membrane repair response masks membrane disturbances caused by cell-penetrating peptide uptake
- 2009
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In: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 23:1, s. 214-223
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Journal article (peer-reviewed)abstract
- Although cell-penetrating peptides are able to deliver cargo into cells, their uptake mechanism is still not fully understood and needs to be elucidated to improve their delivery efficiency. Herein, we present evidence of a new mechanism involved in uptake, the membrane repair response. Recent studies have suggested that there might be a direct penetration of peptides in parallel with different forms of endocytosis. The direct penetration of hydrophilic peptides through the hydrophobic plasma membrane, however, is highly controversial. Three proteins involved in target cell apoptosis—perforin, granulysin, and granzymes—share many features common in uptake of cell-penetrating peptides (e.g., they bind proteoglycans). During perforin uptake, the protein activates the membrane repair response, a resealing mechanism triggered in cells with injured plasma membrane, because of extracellular calcium influx. On activation of the membrane repair response, internal vesicles are mobilized to the site of the disrupted plasma membrane, resealing it within seconds. In this study, we have used flow cytometry, fluorescence, and electron microscopy, together with high-performance liquid chromatography and mass spectrometry, to present evidence that the membrane repair response is able to mask damages caused during cell-penetrating peptide uptake, thus preventing leakage of endogenous molecules out of the cell.—Palm-Apergi, C., Lorents, A., Padari, K., Pooga, M., and Hällbrink, M. The membrane repair response masks membrane disturbances caused by cell-penetrating peptide uptake.
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| 6. |
- Säälik, Pille, et al.
(author)
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Protein delivery with transportans is mediated by caveolae rather than flotillin-dependent pathways
- 2009
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In: Bioconjugate chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 20:5, s. 877-887
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Journal article (peer-reviewed)abstract
- Delivery of large bioactive cargoes into cells with the help of cell-penetrating peptides (CPPs) is mostly based on endocytic processes. Here we map the cellular pathways used by transportan and transportan 10 (TP10) for protein transduction in HeLa cells. CPP-mediated cellular delivery is often suggested to be lipid-raft-dependent; therefore, we used flotillin-1, caveolin, Rab5, and PI3P as markers to elucidate the involvement of these particular endosomal pathways in the protein uptake process. Confocal laser scanning and electron microscopy reveal only a negligible overlap of avidin/neutravidin conveyed into cells by transportans with the raft marker flotillin-1 or early endosomal markers Rab5 and PI3P. However, about 20% of protein−CPP complexes colocalize with the caveolar/caveosomal marker caveolin, and down-regulation of caveolin-1 by siRNA treatment leads to the inhibition of the CPP-mediated protein uptake by 30−50%. On the contrary, the lack of flotillin-1 increases rather than decreases the CPP-mediated protein transport. The participation of the caveolin-1-dependent pathway in CPP-mediated protein delivery was also corroborated by using caveolin-1 knockout mouse embryonic fibroblasts.
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| 7. |
- Urgard, Egon, et al.
(author)
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Pre-administration of PepFect6-microRNA-146a nanocomplexes inhibits inflammatory responses in keratinocytes and in a mouse model of irritant contact dermatitis
- 2016
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In: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 235, s. 195-204
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Journal article (peer-reviewed)abstract
- The skin is a difficult to access tissue for efficient delivery of large and/or chargedmacromolecules, including therapeutic DNA and RNA oligonucleotides. Cell-penetrating peptide PepFect6 (PF6) has been shown to be suitable transport vehicle for siRNAs in cell culture and systemically in vivo in mice. MiR-146a is known as anti-inflammatory miRNA that inhibits multiple factors fromthe nuclear factor (NF)-kappa B pathway in various cell types, including keratinocytes. In this study, PF6 was shown to form unimodal nanocomplexes with miR-146a mimic that entered into human primary keratinocytes, where miR-146a inhibited the expression of its direct targets fromthe NF-kappa B pathway and the genes known to be activated by NF-kappa B, C-C motif ligand (CCL)5 and interleukin (IL)-8. The transfection of miR-146a mimic with PF6 was more efficient in sub-confluent keratinocyte cultures, affected keratinocyte proliferation less and had similar effect on cell viability when compared with a lipid based agent. Subcutaneous pre-administration of PF6-miR-146a nanocomplexes attenuated ear-swelling and reduced the expression of pro-inflammatory cytokines and chemokines IL-6, CCL11, CCL24 and C-X-C motif ligand 1 (CXCL1) in a mouse model of irritant contact dermatitis. Our data demonstrates that PF6-miR-146a nanoparticles might have potential in the development of therapeutics to target inflammatory skin diseases.
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