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  • 1.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assiut University, Egypt.
    Dowaidar, Moataz
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gene delivery using cell penetrating peptides-zeolitic imidazolate frameworks2020In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 300, article id 110173Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs), and metal-organic frameworks (MOFs) are promising as next-generation for the delivery of gene-based therapeutic agents. Oligonucleotide (ON)-mediated assembly of nanostructures composed of hierarchical porous zeolitic imidazolate framework (ZIF-8), and nanoparticles such as graphene oxide (GO), and magnetic nanoparticles (MNPs) for gene therapy are reported. Five different types of non-viral vectors (ZIF-8, RhB@ZIF-8, BSA@ZIF-8, MNPs@ZIF-8, and GO@ZIF-8), and three gene therapeutic agents (plasmid, splice correction oligonucleotides (SCO), and small interfering RNA (siRNA)) were investigated. The polyplexes were characterized and applied for gene transfection. The materials show very low toxicity with high efficiency for luciferase transfection. ZIF-8 enhances the transfection of plasmid, SCO, siRNA of CPPs by 2-8 folds. The mechanism of the cell uptakes was also highlighted. Data reveal cell internalization via scavenger class A (SCARA).

  • 2.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assiut University, Egypt.
    Dowaidar, Moataz
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Carbonized chitosan encapsulated hierarchical porous zeolitic imidazolate frameworks nanoparticles for gene delivery2020In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 302, article id 110200Article in journal (Refereed)
    Abstract [en]

    Hierarchical mesoporous carbon (MPC) nanomaterials derived from the carbonized chitosan (CTS) encapsulated zeolitic imidazolate frameworks (ZIF-8) is synthesized and applied for gene delivery. The synthesis of ZIF-8 is achieved at room temperature using water as a solvent in the presence of CTS within 60 min. The synthesis method offered a hierarchical porous structure of ZIF-8. The carbonization of the prepared materials leads to the formation of MPC nanomaterials. MPC materials were applied as a non-viral vectors for gene delivery using two oligonucleotides (ONs) called Luciferase-expressing plasmid (pGL3), and splice correction oligonucleotides (SCO). The materials are biocompatible and showed insignificant toxicity. The transfection using MPC with and without cell-penetrating peptides (CPPs) was reported. MPC improved the transfection efficiency of CPPs (PepFect 14 (PF-14), and PF-221) by 10 fold due to the synergistic effect of MCP and CPPs. The reasonable mechanism for the cell transfection using these new vectors was also highlighted.

  • 3.
    Adlerz, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Soomets, Ursel
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology. University of Tartu, Estonia.
    Holmlund, Linda
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Virland, Saade
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Iverfeldt, Kerstin
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Down-regulation of amyloid precursor protein by peptide nucleic acid oligomer in cultured rat primary neurons and astrocytes2003In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 336, no 1, p. 55-59Article in journal (Refereed)
    Abstract [en]

    The amyloid precursor protein (APP) and its proteolytic cleavage products, the amyloid P peptides, have been implicated as a cause of Alzheimer's disease. Peptide nucleic acids (PNA), the DNA mimics, have been shown to block the expression of specific proteins at both transcriptional and translational levels. Generally, the cellular uptake of PNA is low. However, recent studies have indicated that the effect of unmodified antisense PNA uptake is more pronounced in nervous tissue. In this study we have shown that biotinylated PNA directed to the initiator codon region of the APP mRNA (-4 - +11) was taken up into the cytoplasm of primary rat cerebellar granule cells and cortical astrocytes, using fluorescence and confocal microscopy studies. Uptake of PNA was faster in neurons than in astrocytes. Western blotting analysis showed that APP was strongly down-regulated in both neurons and astrocytes. Thus, unmodified PNA can be used for studies on the function of APP in neurons and astrocytes.

  • 4.
    Ajayi, Abiodun
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Yu, Xin
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Lindberg, Staffan
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Ström, Anna-Lena
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Expanded ataxin-7 cause toxicity by inducing ROS production from NADPH oxidase complexes in a stable inducible Spinocerebellar ataxia type 7 (SCA7) model2012In: BMC Neuroscience, E-ISSN 1471-2202, Vol. 13, article id 86Article in journal (Refereed)
    Abstract [en]

    Background: Spinocerebellar ataxia type 7 (SCA7) is one of nine inherited neurodegenerative disorders caused by polyglutamine (polyQ) expansions. Common mechanisms of disease pathogenesis suggested for polyQ disorders include aggregation of the polyQ protein and induction of oxidative stress. However, the exact mechanism(s) of toxicity is still unclear. Results: In this study we show that expression of polyQ expanded ATXN7 in a novel stable inducible cell model first results in a concomitant increase in ROS levels and aggregation of the disease protein and later cellular toxicity. The increase in ROS could be completely prevented by inhibition of NADPH oxidase (NOX) complexes suggesting that ATXN7 directly or indirectly causes oxidative stress by increasing superoxide anion production from these complexes. Moreover, we could observe that induction of mutant ATXN7 leads to a decrease in the levels of catalase, a key enzyme in detoxifying hydrogen peroxide produced from dismutation of superoxide anions. This could also contribute to the generation of oxidative stress. Most importantly, we found that treatment with a general anti-oxidant or inhibitors of NOX complexes reduced both the aggregation and toxicity of mutant ATXN7. In contrast, ATXN7 aggregation was aggravated by treatments promoting oxidative stress. Conclusion: Our results demonstrates that oxidative stress contributes to ATXN7 aggregation as well as toxicity and show that anti-oxidants or NOX inhibition can ameliorate mutant ATXN7 toxicity.

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  • 5. Alier, Kwai
    et al.
    Chen, Yishen
    Eriksson Sollenberg, Ulla
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Smith, Peter
    Selective stimulation of GalR1 and GalR2 in rat substantia gelatinosa reveals a cellular basis for the anti- and pro-nociceptive actions of galanin2008In: Pain, ISSN 0304-3959, E-ISSN 1872-6623, Vol. 137, no 1, p. 138-146Article in journal (Refereed)
    Abstract [en]

    Galanin modulates spinal nociceptive processing by interacting with two receptors, GalR1 and GalR2. The underlying neurophysiological mechanisms were examined by whole-cell recording from identified neurons in the substantia gelatinosa of young adult rats. GalR1 was activated with a 'cocktail' containing the GalR1/2 agonist, AR-M 961 (0.5 mu M), in the presence of the GalR2 antagonist, M871 (1.0-2.5 mu M). GalR2 was activated with the selective agonist, AR-M 1896 (0.5-1.0 mu M). Application of the 'GalR1 agonist cocktail' often activated an inwardly-rectifying conductance in delay firing (excitatory) and tonically firing (inhibitory) neurons. This conductance was not activated by AR-M 1896 which instead decreased or increased an outwardly-rectifying conductance at voltages positive to -70 rnV. Despite this variability in its actions on current-voltage relationships, AR-M 1896 very consistently decreased membrane excitability, as measured by cumulative action potential latency in response to a depolarizing current ramp. This strong GalR2-mediated effect was seen in neurons where membrane conductance was decreased, and where membrane excitability might be predicted to increase. GalR2 was also located presynaptically, as AR-M 1896 increased the interevent interval of spontaneous EPSCs in both delay and tonic cells. By contrast, the 'GalR1 agonist cocktail' had little effect on spontaneous EPSCs, suggesting that presynaptic terminals do not express GalR1. These diverse actions of GalR1 and GalR2 activation on both inhibitory and excitatory neurons are discussed in relation to the known spinal antinociceptive and pro-nociceptive actions of galanin, to the possible association of GalR1 with the inhibitory G-protein, G(i/o) and to report that GalR2 activation suppresses Ca(2+) channel currents.

  • 6. Alvarez, Mariano J.
    et al.
    Subramaniam, Prem S.
    Tang, Laura H.
    Grunn, Adina
    Aburi, Mahalaxmi
    Rieckhof, Gabrielle
    Komissarova, Elena V.
    Hagan, Elizabeth A.
    Bodei, Lisa
    Clemons, Paul A.
    Dela Cruz, Filemon S.
    Dhall, Deepti
    Diolaiti, Daniel
    Fraker, Douglas A.
    Ghavami, Afshin
    Kaemmerer, Daniel
    Karan, Charles
    Kidd, Mark
    Kim, Kyoung M.
    Kim, Hee C.
    Kunju, Lakshmi P.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Li, Zhong
    Lee, Jeeyun
    Li, Hai
    LiVolsi, Virginia
    Pfragner, Roswitha
    Rainey, Allison R.
    Realubit, Ronald B.
    Remotti, Helen
    Regberg, Jakob
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Roses, Robert
    Rustgi, Anil
    Sepulveda, Antonia R.
    Serra, Stefano
    Shi, Chanjuan
    Yuan, Xiaopu
    Barberis, Massimo
    Bergamaschi, Roberto
    Chinnaiyan, Arul M.
    Detre, Tony
    Ezzat, Shereen
    Frilling, Andrea
    Hommann, Merten
    Jaeger, Dirk
    Kim, Michelle K.
    Knudsen, Beatrice S.
    Kung, Andrew L.
    Leahy, Emer
    Metz, David C.
    Milsom, Jeffrey W.
    Park, Young S.
    Reidy-Lagunes, Diane
    Schreiber, Stuart
    Washington, Kay
    Wiedenmann, Bertram
    Modlin, Irvin
    Califano, Andrea
    A precision oncology approach to the pharmacological targeting of mechanistic dependencies in neuroendocrine tumors2018In: Nature Genetics, ISSN 1061-4036, E-ISSN 1546-1718, Vol. 50, no 7, p. 979-989Article in journal (Refereed)
    Abstract [en]

    We introduce and validate a new precision oncology framework for the systematic prioritization of drugs targeting mechanistic tumor dependencies in individual patients. Compounds are prioritized on the basis of their ability to invert the concerted activity of master regulator proteins that mechanistically regulate tumor cell state, as assessed from systematic drug perturbation assays. We validated the approach on a cohort of 212 gastroenteropancreatic neuroendocrine tumors (GEP-NETs), a rare malignancy originating in the pancreas and gastrointestinal tract. The analysis identified several master regulator proteins, including key regulators of neuroendocrine lineage progenitor state and immunoevasion, whose role as critical tumor dependencies was experimentally confirmed. Transcriptome analysis of GEP-NET-derived cells, perturbed with a library of 107 compounds, identified the HDAC class I inhibitor entinostat as a potent inhibitor of master regulator activity for 42% of metastatic GEP-NET patients, abrogating tumor growth in vivo. This approach may thus complement current efforts in precision oncology.

  • 7.
    Amelina, Hanna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Holm, Tina
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Cristobal, Susana
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Delivering catalase to yeast peroxisomes using cell-penetrating peptidesIn: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658Article in journal (Refereed)
  • 8. Anderson, Maria E.
    et al.
    Runesson, Johan
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Saar, Indrek
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Robinson, John K.
    Galanin, through GalR1 but not GalR2 receptors, decreases motivation at times of high appetitive behavior2013In: Behavioural Brain Research, ISSN 0166-4328, E-ISSN 1872-7549, Vol. 239, p. 90-93Article in journal (Refereed)
    Abstract [en]

    Galanin is a 29/30-amino acid long neuropeptide that has been implicated in many physiological and behavioral functions. Previous research has shown that i.c.v. administration of galanin strongly stimulates food intake in sated rats when food is freely available, but fails to stimulate this consumption when an operant response requirement is present. Using fixed ratio (FR) schedules, we sought to further clarify galanin's role in motivated behavior by administering galanin i.c.v. to rats working on fixed ratio schedules requiring either a low work condition (FR1) or higher work conditions (FR > 1) to obtain a 0.2% saccharin reward. Rats in the FR > 1 group were assigned to either an FR3, FR5 or FR7 schedule of reinforcement. The rate of reinforcement decreased for only the FR > 1 group as compared to saline controls. Furthermore, injections of GalR1 receptor agonist M617 led to a similar, marginally significant decrease in the number of reinforcers received in the FR > 1 condition, but a decrease was not seen after injections of GalR2 receptor agonist M1153. Taken together, these results show that galanin may be playing a role in decreasing motivation at times of high appetitive behavior, and that this effect is likely mediated by the GalR1 receptor.

  • 9. Anko, Maja
    et al.
    Majhenc, Janja
    Kogej, Ksenija
    Sillard, Rannard
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Anderluh, Gregor
    Zorko, Matjaz
    Influence of stearyl and trifluoromethylquinoline modifications of the cell penetrating peptide TP10 on its interaction with a lipid membrane2012In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1818, no 3, p. 915-924Article in journal (Refereed)
    Abstract [en]

    The PepFect family of cell-penetrating peptides (CPPs) was designed to improve the delivery of nucleic acids across plasma membranes. We present here a comparative study of two members of the family, PepFect3 (PF3) and PepFect6 (PF6), together with their parental CPP transportan-10 (TP10), and their interactions with lipid membranes. We show that the addition of a stearyl moiety to TP10 increases the amphipathicity of these molecules and their ability to insert into a lipid monolayer composed of zwitterionic phospholipids. The addition of negatively charged phospholipids into the monolayer results in decreased binding and insertion of the stearylated peptides, indicating modification in the balance of hydrophobic versus electrostatic interactions of peptides with lipid bilayer, thus revealing some clues for the selective interaction of these CPPs with different lipids. The trifluoromethylquinoline moieties, in PF6 make no significant contribution to membrane binding and insertion. TP10 actively introduces pores into the bilayers of large and giant unilamellar vesicles, while PF3 and PF6 do so only at higher concentrations. This is consistent with the lower toxicity of PR and PF6 observed in previous studies.

  • 10.
    Arrighi, Romanico B. G.
    et al.
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Ebikeme, Charles
    Jiang, Yang
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Ranford-Cartwright, Lisa
    Barrett, Michael P.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Faye, Ingrid
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Cell-penetrating peptide TP10 shows broad-spectrum activity against both Plasmodium falciparum and Trypanosoma brucei brucei2008In: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 52, no 9, p. 3414-3417Article in journal (Refereed)
    Abstract [en]

    Malaria and trypanosomiasis are diseases which afflict millions and for which novel therapies are urgently required. We have tested two well-characterized cell-penetrating peptides (CPPs) for antiparasitic activity. One CPP, designated TP10, has broad-spectrum antiparasitic activity against Plasmodium falciparum, both blood and mosquito stages, and against blood-stage Trypanosoma brucei brucei.

  • 11. Arsov, Zoran
    et al.
    Nemec, Marjana
    Schara, Milan
    Johansson, Henrik
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Zorko, Matjaž
    Cholesterol prevents interaction of the cell-penetrating peptide transportan with model lipid membranes2008In: Journal of Peptide Science, ISSN 1075-2617, E-ISSN 1099-1387, Vol. 14, no 12, p. 1303-1308Article in journal (Refereed)
    Abstract [en]

    Interaction of the cell-penetrating peptide (CPP) cysteine-transportan (Cys-TP) with model lipid membranes was examined by spin-label electron paramagnetic resonance (EPR). Membranes were labeled with lipophilic spin probes and the influence of Cys-TP on membrane structure Was studied. The influence of Cys-TP on membrane permeability was monitored by the reduction of a liposome-trapped water-soluble spin probe. Cys-TP caused lipid ordering in membranes prepared from pure dimyristoylphosphatidylcholine (DMPC) and in DMPC membranes with moderate cholesterol concentration. In addition, Cys-TP caused a large increase in permeation of DMPC membranes. In contrast, with high cholesterol content, at which model lipid membranes are in the so-called liquid-ordered phase, no effect. of Cys-TP was observed, either on Line membrane structure or on the membrane permeability. The interaction between Cys-TP and the lipid membrane therefore depends on the lipid phase. This could be of great. importance for understanding of the CPP-lipid interaction in laterally heterogeneous membranes, white it implies that the CPP-lipid interaction can be different at different points along the membrane.

  • 12. Arukuusk, Piret
    et al.
    Härk, Heleri Heike
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    Utilization of Cell-Penetrating Peptides for In Vivo Delivery of Bioactive Cargo: The Effect of Nanoparticle Formulation2022In: Cell Penetrating Peptides: Methods and Protocols, New York: Humana Press, 2022, 3, p. 247-253Chapter in book (Refereed)
    Abstract [en]

    The efficacy of nanoparticle drugs necessitates the high bioactivity of constituents, but the distribution of the nanoparticles in organisms is mostly determined by their physical properties. Therefore, generation of stable particles with strictly defined characteristics is highly essential. Here we describe a formulation protocol of stable and homogenous CPP/pDNA nanoparticles for in vivo applications. 

  • 13.
    Arukuusk, Piret
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Paernaste, Ly
    Margus, Helerin
    Eriksson, N. K. Jonas
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Vasconcelos, Luis
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Padari, Kaert
    Pooga, Margus
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Differential Endosomal Pathways for Radically Modified Peptide Vectors2013In: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 24, no 10, p. 1721-1732Article in journal (Refereed)
    Abstract [en]

    In the current work we characterize the uptake mechanism of two NickFect family members, NF51 and NF1, related to the biological activity of transfected plasmid DNA (pDNA). Both vectors condense pDNA into small negatively charged nanoparticles that transfect He La cells with equally high efficacy and the delivery is mediated by SCARA3 and SCARA.5 receptors. NF1 condenses DNA into less homogeneous and less stable nanoparticles than NF51. NF51/pDNA nanoparticles enter the cells via macropinocytosis, while NF1/pDNA complexes use clathrin- or caveolae-mediated endocytosis and macropinocytosis. Analysis of separated endosomal compartments uncovered lysomotropic properties of NF51 that was also proven by cotransfection with chloroquine. In summary we characterize how radical modifications in peptides, such as introducing a kink in the structure of NF51 or including extra negative charge by phospho-tyrosine substitution in NF1, resulted in equally high efficacy for gene delivery, although this efficacy is achieved by using differential transfection pathways.

  • 14. Arukuusk, Piret
    et al.
    Paernaste, Ly
    Oskolkov, Nikita
    Copolovici, Dana-Maria
    Margus, Helerin
    Padari, Kaert
    Moell, Kaidi
    Maslovskaja, Julia
    Tegova, Radi
    Kivi, Gaily
    Tover, Andres
    Pooga, Margus
    Ustav, Mart
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    New generation of efficient peptide-based vectors, NickFects, for the delivery of nucleic acids2013In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1828, no 5, p. 1365-1373Article in journal (Refereed)
    Abstract [en]

    Harnessing of a branched structure is a novel approach in the design of cell-penetrating peptides and it has provided highly efficient transfection reagents for intracellular delivery of nucleic acids. The new stearylated TP10 analogs, NickFects, condense plasmid DNA, splice correcting oligonucleotides and short interfering RNAs into stable nanoparticles with a size of 62-160 nm. Such nanoparticles have a negative surface charge (-11 to -18 mV) in serum containing medium and enable highly efficient gene expression, splice correction and gene silencing. One of the novel peptides, NickFect51 is capable of transfecting plasmid DNA into a large variety of cell lines, including refractory suspension and primary cells and in several cases exceeds the transfection level of commercially available reagent Lipofectamine (TM) 2000 without any cytotoxic side effects. Additionally we demonstrate the advantages of NickFect51 in a protein production system, QMCF technology, for expression and production of recombinant proteins in hardly transfectable suspension cells.

  • 15. Arukuusk, Piret
    et al.
    Pärnaste, Ly
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. Tartu University, Estonia.
    PepFects and NickFects for the Intracellular Delivery of Nucleic Acids2015In: Cell-Penetrating Peptides: Methods and Protocols / [ed] Ülo Langel, New York: Springer, 2015, Vol. 1324, p. 303-315Chapter in book (Refereed)
    Abstract [en]

    Nucleic acids can be utilized in gene therapy to restore, alter, or silence gene functions. In order to reveal the biological activity nucleic acids have to reach their intracellular targets by passing through the plasma membrane, which is impermeable for these large and negatively charged molecules. Cell-penetrating peptides (CPPs) condense nucleic acids into nanoparticles using non-covalent complexation strategy and mediate their delivery into the cell, whereas the physicochemical parameters of the nanoparticles determine the interactions with the membranes, uptake mechanism, and subsequent intracellular fate. The nanoparticles are mostly internalized by endocytosis that leads to the entrapment of them in endosomal vesicles. Therefore design of new CPPs that are applicable for non-covalent complex formation strategy and harness endosomolytic properties is highly vital. Here we demonstrate that PepFects and NickFects are efficient vectors for the intracellular delivery of various nucleic acids.This chapter describes how to form CPP/pDNA nanoparticles, evaluate stable nanoparticles formation, and assess gene delivery efficacy.

  • 16. Bavec, Aljosa
    et al.
    Jiang, Yang
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Zorko, Matjaz
    Role of cysteine 341 and arginine 348 of GLP-1 receptor in G-protein coupling2007In: Molecular Biology Reports, ISSN 0301-4851, E-ISSN 1573-4978, Vol. 34, no 1, p. 53-60Article in journal (Refereed)
    Abstract [en]

    We have demonstrated the ability of peptides derived from the third intracellular loop of GLP-1 receptor to differently modulate activity of four different types of G-proteins overexpressed in sf9 cells. In this respect, the involvement of Cys341 in inhibition of Gs and Cys341 in activation of Gs and in inhibition of Gi1, Go, and G11, respectively, indicates their potential role in discrimination between different types of G-proteins. Moreover, these two amino acids from the third intracellular loop might represent an important novel targets for covalent modification by downstream regulators in signaling through GLP-1 receptor.

  • 17. Bell, Thomas J.
    et al.
    Eiríksdóttir, Emelía
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Eberwine, James
    PAIR technology: exon-specific RNA binding protein isolation in live cells2011In: Cell-penetrating peptides: Methods and Protocols / [ed] Ülo Langel, New York: Humana Press, 2011, p. 473-486Chapter in book (Refereed)
    Abstract [en]

    RNA-binding proteins (RBPs) are fundamental regulatory proteins for all forms of transcriptional and posttranscriptional control of gene expression. However, isolating RBPs is technically challenging for investigators. Currently, the most widely used techniques to isolate RBPs are in vitro biochemical approaches. Although these approaches have been useful, they have several limitations. One key limitation to using in vitro biochemical approaches is that RBP–RNA interactions are isolated under nonbiological conditions. Here we review a novel experimental approach to identify RBPs called peptide nucleic acid (PNA)-assisted identification of RBPs (PAIR) technology (Zielinski et al., Proc Natl Acad Sci USA 103:1557–1562, 2006). This technology has two significant advantages over traditional approaches. (1) It overcomes the in vitro limitation of biochemical approaches by allowing investigators to isolate RBP–RNA interactions under in vivo conditions. (2) This technology is highly mRNA specific; it isolates RBPs in an exon-specific manner. By selectively targeting alternatively spliced exons with PAIR technology, investigators can isolate splice variant-specific and mRNA region-specific (5-UTR and 3-UTR) RBP complexes for any mRNA of interest.

  • 18. Blackshear, Alice
    et al.
    Yamamoto, Mihoko
    Anderson, Brenda J.
    Holmes, Philip V.
    Lundström, Linda
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Robinson, John K.
    Intracerebroventricular administration of galanin or galanin receptor subtype 1 agonist M617 induces c-Fos activation in central amygdala and dorsomedial hypothalamus2007In: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 28, no 5, p. 1120-1124Article in journal (Refereed)
    Abstract [en]

    The neuropeptide galanin and galanin receptors are widespread throughout cortical, limbic and midbrain areas implicated in reward, learning/memory, pain, drinking and feeding. While many studies have shown that galanin produces a variety of presynaptic and postsynaptic responses, work studying the effects of galanin on neural activation is limited. The present study examined patterns of c-Fos immunoreactivity resulting from intracerebro-ventricular administration of galanin versus saline injection in awake rats. An initial comprehensive qualitative survey was conducted to identify regions of high c-Fos expression followed up with quantitative analysis. Galanin induced a significant increase in c-Fos levels relative to saline-treated controls in dorsomedial hypothalamus and in the central nucleus of the amygdala. This pattern of activation was also produced by galanin receptor type 1 agonist M617. The present findings confirm that galanin upregulates c-Fos activation in hypothalamic nuclei, and supports roles for galanin in central amygdala-mediated food intake, and Pavlovian conditioning.

  • 19.
    Bárány-Wallje, Elsa
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gaur, Jugnu
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lundberg, Pontus
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Differential membrane perturbation caused by the cell penetrating peptide Tp10 depending on attached cargo2007In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 581, no 13, p. 2389-2393Article in journal (Refereed)
    Abstract [en]

    The membrane leakage caused by the cell penetrating peptide Tp10, a variant of transportan, was studied in large unilamellar vesicles with the entrapped fluorophore calcein. The vesicles were composed of zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. A significant decrease in membrane leakage was found when the 55 kDa streptavidin protein was attached to Tp10. When a 5.4 kDa peptide nucleic acid molecule was attached, the membrane leakage was comparable to that caused by Tp10 alone. The results suggest that direct membrane effects may cause membrane translocation of Tp10 alone and of smaller complexes, whereas these effects do not contribute for larger cargoes.

  • 20. Carreras-Badosa, Gemma
    et al.
    Maslovskaja, Julia
    Periyasamy, Kapilraj
    Urgard, Egon
    Padari, Kärt
    Vaher, Helen
    Tserel, Liina
    Gestin, Maxime
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Kisand, Kai
    Arukuusk, Piret
    Lou, Chenguang
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    Wengel, Jesper
    Pooga, Margus
    Rebane, Ana
    NickFect type of cell-penetrating peptides present enhanced efficiency for microRNA-146a delivery into dendritic cells and during skin inflammation2020In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 262, article id 120316Article in journal (Refereed)
    Abstract [en]

    MicroRNAs (miRNAs) are post-transcriptional gene expression regulators with potential therapeutic applications. miR-146a is a negative regulator of inflammatory processes in both tissue-resident and specialized immune cells and may therefore have therapeutic effect in inflammatory skin diseases. PepFect (PF) and NickFect (NF) type of cell-penetrating peptides (CPPs) have previously been shown to deliver miRNA mimics and/or siRNAs into cell cultures and in vivo. Here, we first demonstrate that selected PF- and NF-type of CPPs support delivery of fluorescent labelled miRNA mimics into keratinocytes (KCs) and dendritic cells (DCs). Second, we show that both PF- and NF-miR-146a nanocomplexes were equally effective in KCs, while NFs were more efficient in DCs as assessed by downregulation of miR-146a-influenced genes. None of miRNA nanocomplexes with the tested CPPs influenced the viability of KCs and DCs nor caused activation of DCs according to CD86 and CD83 markers. Transmission electron microscopy analysis with Nanogold-labelled miR-146a mimics and assessment of endocytic trafficking pathways revealed endocytosis as an active route of delivery in both KCs and DCs for all tested CPPs. However, consistent with the higher efficiency, NF-delivered miR-146a was detected more often outside endosomes in DCs. Finally, pre-injection of NF71:miR-146a nanocomplexes was confirmed to suppress inflammatory responses in a mouse model of irritant contact dermatitis as shown by reduced ear swelling response and downregulation of pro-inflammatory cytokines, including IL-6, IL-1 beta, IL-33 and TNF-alpha. In conclusion, NF71 efficiently delivers miRNA mimics into KCs as well as DCs, and therefore may have advantage in therapeutic delivery of miRNAs in case of inflammatory skin diseases.

  • 21. Carter, Victoria
    et al.
    Underhill, Ann
    Baber, Ibrahima
    Sylla, Lakamy
    Baby, Mounirou
    Larget-Thiery, Isabelle
    Zettor, Agnès
    Bourgouin, Catherine
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Faye, Ingrid
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Otvos, Laszlo
    Wade, John D.
    Coulibaly, Mamadou B.
    Traore, Sekou F.
    Tripet, Frederic
    Eggleston, Paul
    Hurd, Hilary
    Killer bee molecules: antimicrobial peptides as effector molecules to target sporogonic stages of Plasmodium2013In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 9, no 11, article id e1003790Article in journal (Refereed)
    Abstract [en]

    A new generation of strategies is evolving that aim to block malaria transmission by employing genetically modified vectors or mosquito pathogens or symbionts that express anti-parasite molecules. Whilst transgenic technologies have advanced rapidly, there is still a paucity of effector molecules with potent anti-malaria activity whose expression does not cause detrimental effects on mosquito fitness. Our objective was to examine a wide range of antimicrobial peptides (AMPs) for their toxic effects on Plasmodium and anopheline mosquitoes. Specifically targeting early sporogonic stages, we initially screened AMPs for toxicity against a mosquito cell line and P. berghei ookinetes. Promising candidate AMPs were fed to mosquitoes to monitor adverse fitness effects, and their efficacy in blocking rodent malaria infection in Anopheles stephensi was assessed. This was followed by tests to determine their activity against P. falciparum in An. gambiae, initially using laboratory cultures to infect mosquitoes, then culminating in preliminary assays in the field using gametocytes and mosquitoes collected from the same area in Mali, West Africa. From a range of 33 molecules, six AMPs able to block Plasmodium development were identified: Anoplin, Duramycin, Mastoparan X, Melittin, TP10 and Vida3. With the exception of Anoplin and Mastoparan X, these AMPs were also toxic to an An. gambiae cell line at a concentration of 25 µM. However, when tested in mosquito blood feeds, they did not reduce mosquito longevity or egg production at concentrations of 50 µM. Peptides effective against cultured ookinetes were less effective when tested in vivo and differences in efficacy against P. berghei and P. falciparum were seen. From the range of molecules tested, the majority of effective AMPs were derived from bee/wasp venoms.

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  • 22. Cerrato, Carmine Pasquale
    et al.
    Kivijärvi, Tove
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    Mitochondrial Targeting Probes, Drug Conjugates, and Gene Therapeutics2022In: Cell Penetrating Peptides: Methods and Protocols / [ed] Ülo Langel, New York: Humana Press, 2022, p. 429-446Chapter in book (Refereed)
    Abstract [en]

    Mitochondria represent an important drug target for many phatology, including neurodegeneration, metabolic disease, heart failure, ischemia-reperfusion injury, and cancer. Mitochondrial dysfunctions are caused by mutation in mitochondrial DNA or in nuclear genes encoding mitochondrial proteins. Cell-penetrating peptides (CPPs) have been employed to overcome biological barriers, target this organelle, and therapeuticaly restore mitochondrial functions. Here, we describe recent methods used to deliver oligonucleotides targeting mitochondrial protein by using mitochondrial penetrating peptides. In particular, we highlight recent advances of formulated peptides/oligonucleotides nanocomplexes as a proof-of-principle for pharmaceutical form of peptide-based therapeutics. 

  • 23.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Kivijärvi, Tove
    Tozzi, Roberta
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Peptides targeting mitochondria for efficient delivery of therapeutic biomoleculesManuscript (preprint) (Other academic)
  • 24.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Kivijärvi, Tove
    Tozzi, Roberta
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Lehto, Tõnis
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gestin, Maxime
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    Intracellular delivery of therapeutic antisense oligonucleotides targeting mRNA coding mitochondrial proteins by cell-penetrating peptides2020In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 8, no 47, p. 10825-10836Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides are a promising therapeutic strategy for a wide variety of degenerative diseases, ageing, and cancer. Among the multitude of cell-penetrating peptides, PepFect14 has been preferentially used in our laboratory for oligonucleotide delivery into cells and in vivo mouse models. However, this activity has mainly been reported towards cytoplasm and nuclei, while the mentioned disorders have been linked to mitochondrial defects. Here, we report a library generated from a combinatorial covalent fusion of a mitochondrial-penetrating peptide, mtCPP1, and PepFect14 in order to deliver therapeutic biomolecules to influence mitochondrial protein expression. The non-covalent complexation of these peptides with oligonucleotides resulted in nano-complexes affecting biological functions in the cytoplasm and on mitochondria. This delivery system proved to efficiently target mitochondrial genes, providing a framework for the development of mitochondrial peptide-based oligonucleotide technologies with the potential to be used as a treatment for patients with mitochondrial disorders.

  • 25. Cerrato, Carmine Pasquale
    et al.
    Kivijärvi, Tove
    Tozzi, Roberta
    Lehto, Tõnis
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gestin, Maxime
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Intracellular Delivery of Therapeutic Antisense Oligonucleotides Targeting mRNACoding Mitochondrial Proteins by Cell-Penetrating PeptidesManuscript (preprint) (Other academic)
    Abstract [en]

    Cell-penetrating peptides are a promising therapeutic strategy for a wide variety of degenerative diseases, ageing, and cancer. Among the multitude of cellpenetrating peptides, PepFect14 has been preferentially used in our laboratory for oligonucleotide delivery into cells and in vivo mouse models. However, this activity has mainly been reported towards cytoplasm and nuclei, while the mentioned disorders have been linked to mitochondrial defects. Here, we report a library generated from a combinatorial covalent fusion of a mitochondrial-penetrating peptide, mtCPP1, and PepFect14 in order to deliver therapeutic biomolecules to influence mitochondrial protein expression. The non-covalent complexation of these peptides with oligonucleotides resulted in nanocomplexes affecting biological functions in the cytoplasm and on mitochondria. This delivery system proved to efficiently target mitochondrial genes, providing a framework for the development of mitochondrial peptide-based oligonucleotide technologies with the potential to be used as a treatment for patients with mitochondrial disorders.

  • 26.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Künnapuu, Kadri
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Cell-penetrating peptides with intracellular organelle targeting2017In: Expert Opinion on Drug Delivery, ISSN 1742-5247, E-ISSN 1744-7593, Vol. 14, no 2, p. 245-255Article, review/survey (Refereed)
    Abstract [en]

    INTRODUCTION: One of the major limiting steps in order to have an effective drug is the passage through one or more cell membranes to reach its site of action. To reach the action-site, the specific macromolecules are required to be delivered specifically to the cell compartment/organelle in their (pre)active form.

    AREAS COVERED: In this review, we will discuss cell-penetrating peptides (CPPs) developed in the last decade to transport small RNA/DNA, plasmids, antibodies, and nanoparticles into specific sites of the cell. The article describes CPPs in complex with cargo molecules that target specific intracellular organelles and their potential for pharmacological or clinical use.

    EXPERT OPINION: Organelle targeting is the ultimate goal to ensure selective delivery to the site of action in the cells. CPP technologies represent an important strategy to address drug delivery to specific intracellular compartments by covalent conjugation to targeting sequences, potentially enabling strategies to combat genomic diseases as well as infections, cancer, neurodegenerative and hereditary diseases. They have proven to be successful in delivering various therapeutic agents into cells however, further in vivo experiments and clinical trials are required to demonstrate the efficacy of this technology.

  • 27. Cerrato, Carmine Pasquale
    et al.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    An update on cell-penetrating peptides with intracellular organelle targeting2022In: Expert Opinion on Drug Delivery, ISSN 1742-5247, E-ISSN 1744-7593, Vol. 19, no 2, p. 133-146Article, review/survey (Refereed)
    Abstract [en]

    Introduction Cell-penetrating peptide (CPP) technologies represent an important strategy to address drug delivery to specific intracellular compartments by covalent conjugation to targeting sequences, potentially enabling strategies to combat most diseases.

    Areas covered This updated review article provides an overview of current intracellular organelle targeting by CPP. The targeting strategies of CPP and CPP/cargo complexes to specific cells or intracellular organelles are summarized, and the review provides an update on the current data for their pharmacological and therapeutical applications.

    Expert opinion Targeted drug delivery is moving from the level of tissue or specific pathogenic cell to the level of specific organelle that is the target of the drug, an important aspect in drug design and development. Organelle-targeted drug delivery results in improved efficacy, ability to control mode of action, reduction of undesired toxicities and side effects, and the possibility to overcome drug resistance mechanisms.

  • 28.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    Cell-Penetrating Peptides Targeting Mitochondria2018In: Mitochondrial Biology and Experimental Therapeutics / [ed] Paulo J. Oliveira, Cham: Springer, 2018, p. 593-611Chapter in book (Refereed)
    Abstract [en]

    Mitochondria are key organelles with essential functions and fundamental roles in cell death and survival signaling. Consequently, they are involved in a wide range of diseases with a great diversity of clinical appearance, which makes them attractive as target for drugs to treat metabolic and degenerative diseases and cancer. Efficient methods for specific intracellular delivery of exogenous compounds, including biochemically active small molecules, imaging agents, peptides, peptide nucleic acids, proteins, RNA, DNA, and nanoparticles, would be beneficial for research and patients. A sustained effort in the last 20 years has been done to exploit cell-penetrating peptides (CPPs) for the delivery of such useful cargoes in vitro  and in vivo  because of their biocompatibility, ease of synthesis, and controllable physical chemistry. Here, we discuss the mechanisms by which CPPs can function, the use of this alternative as well as strategies used to target mitochondria and the implications for drug delivery.

  • 29.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Effect of a Fusion Peptide by Covalent Conjugation of a Mitochondrial Cell-Penetrating Peptide and a Glutathione Analog Peptide2017In: Molecular therapy. Methods & clinical development, ISSN 2399-6951, E-ISSN 2329-0501, Vol. 5, p. 221-231Article in journal (Refereed)
    Abstract [en]

    Previously, we designed and synthesized a library of mitochondrial antioxidative cell-penetrating peptides (mtCPPs) superior to the parent peptide, SS31, to protect mitochondria from oxidative damage. A library of antioxidative glutathione analogs called glutathione peptides (UPFs), exceptional in hydroxyl radical elimination compared with glutathione, were also designed and synthesized. Here, a follow-up study is described, investigating the effects of the most promising members from both libraries on reactive oxidative species scavenging ability. None of the peptides influenced cell viability at the concentrations used. Fluorescence microscopy studies showed that the fluorescein-mtCPP1-UPF25 (mtgCPP) internalized into cells, and spectrofluorometric analysis determined the presence and extent of peptide into different cell compartments. mtgCPP has superior antioxidative activity compared with mtCPP1 and UPF25 against H2O2 insult, preventing ROS formation by 2- and 3-fold, respectively. Moreover, we neither observed effects on mitochondrial membrane potential nor production of ATP. These data indicate that mtgCPP is targeting mitochondria, protecting them from oxidative damage, while also being present in the cytosol. Our hypothesis is based on a synergistic effect resulting from the fused peptide. The mitochondrial peptide segment is targeting mitochondria, whereas the glutathione analog peptide segment is active in the cytosol, resulting in increased scavenging ability.

  • 30.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Lehto, Tõnis
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Peptide-based vectors: recent developments2014In: Biomolecular Concepts, ISSN 1868-503X, Vol. 5, no 6, p. 479-488Article in journal (Refereed)
    Abstract [en]

    Peptides and peptide-cargo complexes have been used for drug delivery and gene therapy. One of the most used delivery vectors are cell-penetrating peptides, due to their ability to be taken up by a variety of cell types and deliver a large variety of cargoes through the cell membrane with low cytotoxicity. In vitro and in vivo studies have shown their possibility and full effectiveness to deliver oligonucleotides, plasmid DNA, small interfering RNAs, antibodies, and drugs. We report in this review some of the latest strategies for peptide-mediated delivery of nucleic acids. It focuses on peptide-based vectors for therapeutic molecules and on nucleic acid delivery. In addition, we discuss recent applications and clinical trials.

  • 31.
    Cerrato, Carmine Pasquale
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Pirisinu, Marco
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Sassari, Italy.
    Vlachos, Efstathios Nikolaos
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Novel cell-penetrating peptide targeting mitochondria2015In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 29, no 11, p. 4589-4599Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are short, nontoxic peptides with cationic and/or amphipathic properties able to cross the cellular membrane. CPPs are used for the delivery of a wide variety of cargoes, such as proteins, oligonucleotides, and therapeutic molecules. The aim of the present study was to synthesize unusually small novel CPPs targeting mitochondria based on the Szeto-Schiller peptide (SS-31) to influence intramitochondrial processes and to improve the biologic effects. All the peptides used were synthesized manually using 9-fluorenylmethyloxycarbonyl chemistry. In the first part of the study, HeLa 705, U87, and bEnd.3 cells were used as in vitro delivery model. Cells were incubated for 24 h at 37°C and 5% CO2 with different concentrations of our peptides. Cell proliferation assay was performed to evaluate cell viability. Biologic effects such as mitochondrial membrane potential and antioxidant activity were evaluated. H2O2 was used as positive control. Uptake studies were performed using peptides conjugated with 5(6)-carboxyfluorescein (FAM). Fluorescent microscopy was used to determine presence and localization of peptides into the cells. Isolated mitochondria from pretreated cells and mitochondria treated after isolation were used to confirm the targeting ability of the peptide. Uptake of FAM alone was used as negative control. Microscopy studies confirmed the ability of peptides to penetrate cell. Localization analysis showed increase in uptake by 35% compared with SS-31. Mitochondrial CPP 1 (mtCPP-1) had no effect on mitochondrial membrane potential and prevented reactive oxygen species formation in bEnd.3 cells by 2-fold compared with SS-31. No cytotoxicity was observed even at high concentration (100 µM). These data suggest that mtCPP-1 is a mitochondrial CPP and protect mitochondria from oxidative damage due to its own antioxidant activities.-Cerrato, C. P., Pirisinu M., Vlachos E. N., Langel, Ü. Novel cell-penetrating peptide targeting mitochondria.

  • 32.
    Cerrato, Carmine
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Veiman, Kadi-Liis
    Laboratory of Molecular Biotechnology, Institute of Technology, Tartu University, Tartu, Estonia.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Advances in peptide delivery2015In: Advances in the Discovery and Development of Peptide Therapeutics, Future Science Group , 2015, p. 160-171Chapter in book (Refereed)
  • 33. Copolovici, Dana Maria
    et al.
    Langel, Kent
    Eriste, Elo
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Cell-Penetrating Peptides: Design, Synthesis, and Applications2014In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 8, no 3, p. 1972-1994Article, review/survey (Refereed)
    Abstract [en]

    The intrinsic property of cell-penetrating peptides (CPPs) to deliver therapeutic molecules (nucleic acids, drugs, imaging agents) to cells and tissues in a nontoxic manner has indicated that they may be potential components of future drugs and disease diagnostic agents. These versatile peptides are simple to synthesize, functionalize, and characterize yet are able to deliver covalently or noncovalently conjugated bioactive cargos (from small chemical drugs to large plasmid DNA) inside cells, primarily via endocytosis, in order to obtain high levels of gene expression, gene silencing, or tumor targeting. Typically, CPPs are often passive and nonselective yet must be functionalized or chemically modified to create effective delivery vectors that succeed in targeting specific cells or tissues. Furthermore, the design of clinically effective systemic delivery systems requires the same amount of attention to detail in both design of the delivered cargo and the cell-penetrating peptide used to deliver it.

  • 34. Dash-Wagh, Suvarna
    et al.
    Jacob, Stefan
    Lindberg, Staffan
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Fridberger, Anders
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Ulfendahl, Mats
    Intracellular Delivery of Short Interfering RNA in Rat Organ of Corti Using a Cell-penetrating Peptide PepFect62012In: Molecular Therapy Nucleic Acids, E-ISSN 2162-2531, Vol. 1, no e61Article in journal (Refereed)
    Abstract [en]

    RNA interference (RNAi) using short interfering RNA (siRNA) is an attractive therapeutic approach for treatment of dominant-negative mutations. Some rare missense dominant-negative mutations lead to congenital-hearing impairments. A variety of viral vectors have been tested with variable efficacy for modulating gene expression in inner ear. However, there is concern regarding their safety for clinical use. Here, we report a novel cell-penetrating peptide (CPP)-based nonviral approach for delivering siRNA into inner ear tissue using organotypic cultures as model system. PepFect6 (PF6), a variant of stearyl-TP10, was specially designed for improved delivery of siRNA by facilitating endosomal release. We show that PF6 was internalized by all cells without inducing cytotoxicity in cochlear cultures. PF6/siRNA nanoparticles lead to knockdown of target genes, a housekeeping gene and supporting cell-specific connexin 26. Interestingly, application of PF6/connexin 26 siRNA exhibited knockdown of both connexin 26 and 30 mRNA and their absence led to impaired intercellular communication as demonstrated by reduced transfer of calcein among the PF6/connexin 26-siRNA-treated cells. Thus, we conclude that PF6 is an efficient nonviral vector for delivery of siRNA, which can be applied as a tool for the development of siRNA-based therapeutic applications for hearing impairments.

  • 35. Dash-Wagh, Suvarna
    et al.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Ulfendahl, Mats
    PepFect6 Mediated SiRNA Delivery into Organotypic Cultures2016In: SiRNA Delivery Methods: Methods and Protocols / [ed] K. Shum, J. Rossi, TOTOWA: HUMANA PRESS INC , 2016, Vol. 1364, p. 27-35Chapter in book (Refereed)
    Abstract [en]

    Gene silencing by small interfering RNA (SiRNA) is an attractive therapeutic approach for pathological disorders that targets a specific gene. However, its applications are limited, as naked RNA is rapidly degraded by RNases and is inadequately internalized by the target cells in the body. Several viral and non-viral vectors have been described to improve the delivery of SiRNAs both in cultured cells as well as in vivo. Increasing evidence suggests that cell-penetrating peptides (CPPs) are an efficient, non-cytotoxic tool for intracellular delivery of SiRNA. Recently, a new peptide, PepFect6 (PF6), based system has been described for efficient SiRNA delivery in various cell types. PF6 is an amphipathic stearyl-TP10 peptide carrying a pH titratable trifluoromethylquinoline moiety that facilitate endosomal release. PF6 forms stable non-covalent complexes with SiRNA. Upon internalization, the complexes rapidly escape the endosomal compartment, resulting in robust RNA interference (RNAi) responses. This chapter describes a protocol to use the PF6-nanoparticle technology for SiRNA delivery into organotypic cultures of the inner ear i.e., cochlea. We also highlight different critical points in the peptide/SiRNA complex preparation, transfection and in analyzing the efficacy of PF6-SiRNA associated RNAi response.

  • 36. de Mello, Lucas R.
    et al.
    Porosk, Ly
    Lourenco, Thiago C.
    Garcia, Bianca B. M.
    Costa, Carlos A. R.
    Han, Sang W.
    de Souza, Juliana S.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    da Silva, Emerson R.
    Amyloid-like Self-Assembly of a Hydrophobic Cell-Penetrating Peptide and Its Use as a Carrier for Nucleic Acids2021In: ACS Applied Bio Materials, E-ISSN 2576-6422, Vol. 4, no 8, p. 6404-6416Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are a topical subject potentially exploitable for creating nanotherapeutics for the delivery of bioactive loads. These compounds are often classified into three major categories according to their physicochemical characteristics: cationic, amphiphilic, and hydrophobic. Among them, the group of hydrophobic CPPs has received increasing attention in recent years due to toxicity concerns posed by highly cationic CPPs. The hexapeptide PFVYLI (P, proline; F, phenylalanine; V, valine; Y, tyrosine; L, leucine; and I, isoleucine), a fragment derived from the C-terminal portion of alpha 1-antitrypsin, is a prototypal example of hydrophobic CPP. This sequence shows reduced cytotoxicity and a capacity of nuclear localization, and its small size readily hints at its suitability as a building block to construct nanostructured materials. In this study, we examine the self-assembling properties of PFVYLI and investigate its ability to form noncovalent complexes with nucleic acids. By using a combination of biophysical tools including synchrotron small-angle X-ray scattering and atomic force microscopy-based infrared spectroscopy, we discovered that this CPP self-assembles into discrete nanofibrils with remarkable amyloidogenic features. Over the course of days, these fibrils coalesce into rodlike crystals that easily reach the micrometer range. Despite lacking cationic residues in the composition, PFVYLI forms noncovalent complexes with nucleic acids that retain beta-sheet pairing found in amyloid aggregates. In vitro vectorization experiments performed with doublestranded DNA fragments indicate that complexes promote the internalization of nucleic acids, revealing that tropism toward cell membranes is preserved upon complexation. On the other hand, transfection assays with splice-correction oligonucleotides (SCOs) for luciferase expression show limited bioactivity across a narrow concentration window, suggesting that the propensity to form amyloidogenic aggregates may trigger endosomal entrapment. We anticipate that the findings presented here open perspectives for using this archetypical hydrophobic CPP in the fabrication of nanostructured scaffolds, which potentially integrate properties of amyloids and translocation capabilities of CPPs.

  • 37. Dobchev, D. A.
    et al.
    Mäger, I.
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Tulp, I.
    Karelson, G.
    Tamm, T.
    Tamm, K.
    Jänes, J.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Karelson, M.
    Prediction of Cell-Penetrating Peptides using Artificial Neural Networks2010In: Current Computer-Aided Drug Design, ISSN 1573-4099, Vol. 6, no 2, p. 79-89Article in journal (Refereed)
    Abstract [en]

    An investigation of cell-penetrating peptides (CPPs) by using combination of Artificial Neural Networks (ANN) and Principle Component Analysis (PCA) revealed that the penetration capability (penetrating/non-penetrating) of 101 examined peptides can be predicted with accuracy of 80%-100%. The inputs of the ANN are the main characteristics classifying the penetration. These molecular characteristics (descriptors) were calculated for each peptide and they provide bio-chemical insights for the criteria of penetration. Deeper analysis of the PCA results also showed clear clusterization of the peptides according to their molecular features.

  • 38.
    Dowaidar, Moataz
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Freimann, Krista
    Kurrikof, Kaido
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Magnetic Nanoparticle Assisted Self-assembly of Cell Penetrating Peptides-Oligonucleotides Complexes for Gene Delivery2017In: Scientific Reports, E-ISSN 2045-2322, Vol. 7, article id 9159Article in journal (Refereed)
    Abstract [en]

    Magnetic nanoparticles (MNPs, Fe3O4) incorporated into the complexes of cell penetrating peptides (CPPs)-oligonucleotides (ONs) promoted the cell transfection for plasmid transfection, splice correction, and gene silencing efficiencies. Six types of cell penetrating peptides (CPPs; PeptFect220 (denoted PF220), PF221, PF222, PF223, PF224 and PF14) and three types of gene therapeutic agents (plasmid (pGL3), splicing correcting oligonucleotides (SCO), and small interfering RNA (siRNA) were investigated. Magnetic nanoparticles incorporated into the complexes of CPPs-pGL3, CPPs-SCO, and CPPs-siRNA showed high cell biocompatibility and efficiently transfected the investigated cells with pGL3, SCO, and siRNA, respectively. Gene transfer vectors formed among PF14, SCO, and MNPs (PF14-SCO-MNPs) showed a superior transfection efficiency (up to 4-fold) compared to the noncovalent PF14-SCO complex, which was previously reported with a higher efficiency compared to commercial vector called Lipofectamine™2000. The high transfection efficiency of the new complexes (CPPs-SCO-MNPs) may be attributed to the morphology, low cytotoxicity, and the synergistic effect of MNPs and CPPs. PF14-pDNA-MNPs is an efficient complex for in vivo gene delivery upon systemic administration. The conjugation of CPPs-ONs with inorganic magnetic nanoparticles (Fe3O4) may open new venues for selective and efficient gene therapy.

  • 39.
    Dowaidar, Moataz
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Assuit University, Egypt.
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Chitosan enhances gene delivery of oligonucleotide complexes with magnetic nanoparticles–cell-penetrating peptide2018In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 33, no 3, p. 392-401Article in journal (Refereed)
    Abstract [en]

    Gene-based therapies, including the delivery of oligonucleotides, offer promising methods for the treatment of cancer cells. However, they have various limitations including low efficiency. Herein, cell-penetrating peptides (CPPs)-conjugated chitosan-modified iron oxide magnetic nanoparticles (CPPs-CTS@MNPs) with high biocompatibility as well as high efficiency were tested for the delivery of oligonucleotides such as plasmid pGL3, splice correction oligonucleotides, and small-interfering RNA. A biocompatible nanocomposite, in which CTS@MNPs was incorporated in non-covalent complex with CPPs-oligonucleotide, is developed. Modifying the surface of magnetic nanoparticles with cationic chitosan-modified iron oxide improved the performance of magnetic nanoparticles-CPPs for oligonucleotide delivery. CPPs-CTS@MNPs complexes enhance oligonucleotide transfection compared to CPPs@MNPs or CPPs. The hydrophilic character of CTS@MNPs improves complexation with plasmid pGL3, splice correction oligonucleotides, and small-interfering RNA payload, which consequently resulted in not only strengthening the colloidal stability of the constructed complex but also improving their biocompatibility. Transfection using PF14-splice correction oligonucleotides-CTS@MNPs showed sixfold increase of the transfection compared to splice correction oligonucleotides-PF14 that showed higher transfection than the commercially available lipid-based vector Lipofectamine™ 2000. Nanoscaled CPPs-CTS@MNPs comprise a new family of biomaterials that can circumvent some of the limitations of CPPs or magnetic nanoparticles.

  • 40.
    Dowaidar, Moataz
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Abdelhamid, Hani Nasser
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Graphene oxide nanosheets in complex with cell penetrating peptides for oligonucleotides delivery2017In: Biochimica et Biophysica Acta - General Subjects, ISSN 0304-4165, E-ISSN 1872-8006, Vol. 1861, no 9, p. 2334-2341Article in journal (Refereed)
    Abstract [en]

    A new strategy for gene transfection using the nanocarrier of cell penetrating peptides (CPPs; PepFect14 (PF14) or PepFect14 (PF14) (PF221)) in complex with graphene oxide (GO) is reported. GO complexed with CPPs and plasmid (pGL3), splice correction oligonucleotides (SCO) or small interfering RNA (siRNA) are performed. Data show adsorption of CPPs and oligonucleotides on the top of the graphenic lamellar without any observed change of the particle size of GO. GO mitigates the cytotoxicity of CPPs and improves the material biocompatibility. Complexes of GO-pGL3-CPPs (CPPs; PF14 or PF221) offer 2.1–2.5 fold increase of the cell transfection compared to pGL3-CPPs (CPPs; PF14 or PF221). GO-SCO-PF14 assemblies effectively transfect the cells with an increase of > 10–25 fold compared to the transfection using PF14. The concentration of GO plays a significant role in the material nanotoxicity and the transfection efficiency. The results open a new horizon in the gene treatment using CPPs and offer a simple strategy for further investigations.

  • 41.
    Dowaidar, Moataz
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Abdelhamid, Hani Nasser
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Tartu, Estonia.
    Improvement of Transfection with PepFects Using Organic and Inorganic Materials2022In: Cell Penetrating Peptides: Methods and Protocols / [ed] Ülo Langel, New York: Humana Press, 2022, 3, p. 555-567Chapter in book (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are a promising non-viral vector for gene and drug delivery. CPPs exhibit high cell transfection, and are biocompatible. They can be also conjugated with organic and inorganic nanomaterials, such as magnetic nanoparticles (MNPs), graphene oxide (GO), metal-organic frameworks (MOFs), and chitosan. Nanomaterials offered a high specific surface area and provided relatively straightforward methods to be modified with biomolecules including CPPs and oligonucleotides (ONs). Novel nanomaterials conjugates with CPP/ONs complexes are therefore of interest for cell transfection with high efficiency. In this chapter, we described a summary of the non-viral vectors consisting of CPPs and nanomaterials. The book chapter also included a protocol to generate hybrid biomaterials consisting of CPPs and nanoparticles (NPs) for the delivery of oligonucleotides. The conjugation of NPs with CPPs serves as an effective platform for gene therapy with high cell transfection efficiency. The protocol is simple, offers high cell transfection compared to the CPPs-ONs complexes, and can be used for further improvements using external stimuli.

  • 42.
    Dowaidar, Moataz
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Gestin, Maxime
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Cerrato, Carmine Pasquale
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Jafferali, Mohammed Hakim
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Margus, Helerin
    Kivistik, Paula Ann
    Ezzat, Kariem
    Hallberg, Einar
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Pooga, Margus
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Role of autophagy in cell-penetrating peptide transfection model2017In: Scientific Reports, E-ISSN 2045-2322, Vol. 7, article id 12635Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) uptake mechanism is still in need of more clarification to have a better understanding of their action in the mediation of oligonucleotide transfection. In this study, the effect on early events (1 h treatment) in transfection by PepFect14 (PF14), with or without oligonucleotide cargo on gene expression, in HeLa cells, have been investigated. The RNA expression profile was characterized by RNA sequencing and confirmed by qPCR analysis. The gene regulations were then related to the biological processes by the study of signaling pathways that showed the induction of autophagy-related genes in early transfection. A ligand library interfering with the detected intracellular pathways showed concentration-dependent effects on the transfection efficiency of splice correction oligonucleotide complexed with PepFect14, proving that the autophagy process is induced upon the uptake of complexes. Finally, the autophagy induction and colocalization with autophagosomes have been confirmed by confocal microscopy and transmission electron microscopy. We conclude that autophagy, an inherent cellular response process, is triggered by the cellular uptake of CPP-based transfection system. This finding opens novel possibilities to use autophagy modifiers in future gene therapy.

  • 43.
    Dowaidar, Moataz
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Regberg, Jakob
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Dobchev, Dimitar A.
    Lehto, Tõnis
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Karelson, Mati
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Refinement of a Quantitative Structure–Activity Relationship Model for Prediction of Cell-Penetrating Peptide Based Transfection Systems2017In: International Journal of Peptide Research and Therapeutics, E-ISSN 1573-3904, Vol. 23, no 1, p. 91-100Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptide (CPP) based transfection systems (PBTS) are a promising class of drug delivery vectors. CPPs are short mainly cationic peptides capable of delivering cell non-permeant cargo to the interior of the cell. Some CPPs have the ability to form non-covalent complexes with oligonucleotides for gene therapy applications. In this study, we use quantitative structure–activity relationships (QSAR), a statistical method based on regression data analysis. Here, a fragment QSAR (FQSAR) model is developed to predict new peptides based on standard alpha helical conformers and Assisted Model Building with Energy Refinement molecular mechanics simulations of previous peptides. These new peptides were examined for plasmid transfection efficiency and compared with their predicted biological activity. The best predicted peptides were capable of achieving plasmid transfection with significant improvement compared to the previous generation of peptides. Our results demonstrate that FQSAR model refinement is an efficient method for optimizing PBTS for improved biological activity.

  • 44. Ehrlich, Kersti
    et al.
    Viirlaid, Säde
    Mahlapuu, Riina
    Saar, Külliki
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Kullisaar, Tiiu
    Zilmer, Mihkel
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Soomets, Ursel
    Design, synthesis and properties of novel powerful antioxidants, glutathione analogues2007In: Free radical research, ISSN 1071-5762, E-ISSN 1029-2470, Vol. 41, no 7, p. 779-787Article in journal (Refereed)
    Abstract [en]

    Glutathione (GSH) is the major low-molecular weight antioxidant in mammalian cells. Thus, its analogues carrying similar and/or additional positive properties might have clinical perspectives. Here, we report the design and synthesis of a library of tetrapeptidic GSH analogues called UPF peptides. Compared to cellular GSH our designed peptidic analogues showed remarkably higher hydroxyl radical scavenging ability (EC50 of GSH: 1231.0 +/- 311.8 mu M; EC50 of UPF peptides: from 0.03 to 35 mu M) and improved antiradical efficiency towards a stable alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical. The best of UPF peptides was 370-fold effective hydroxyl radical scavengers than melatonin (EC50: 11.4 +/- 1.0 mu M). We also found that UPF peptides do not influence the viability and membrane integrity of K562 human erythroleukemia cells even at 200 mu M concentration. Dimerization of GSH and UPF peptides was compared in water and in 0.9% saline solutions. The results, together with an earlier finding that UPF1 showed protective effects in global cerebral ischemia model in rats, suggest that UPF peptides might serve both as potent antioxidants as well as leads for design of powerful non-peptidic antioxidants that correct oxidative stress-driven events.

  • 45.
    Eiríksdóttir, Emelía
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Konate, Karidia
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Divita, Gilles
    Deshayes, Sébastien
    Secondary Structure of Cell-Penetrating Peptides Controls Membrane Interaction and Insertion2010In: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1798, no 6, p. 1119-1128Article in journal (Refereed)
    Abstract [en]

    The clinical use of efficient therapeutic agents is often limited by the poor permeability of the biological membranes. In order to enhance their cell delivery, short amphipathic peptides called cell-penetrating peptides (CPPs) have been intensively developed for the last two decades. CPPs are based either on protein transduction domains, model peptide or chimeric constructs and have been used to deliver cargoes into cells through either covalent or non-covalent strategies. Although several parameters are simultaneously involved in their internalization mechanism, recent focuses on CPPs suggested that structural properties and interactions with membrane phospholipids could play a major role in the cellular uptake mechanism. In the present work, we report a comparative analysis of the structural plasticity of 10 well-known CPPs as well as their ability to interact with phospholipid membranes. We propose a new classification of CPPs based on their structural properties, affinity for phospholipids and internalization pathways already reported in the literature.

  • 46.
    Eiríksdóttir, Emelía
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Rosenthal-Aizman, Katri
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    An improved synthesis of releasable luciferin-CPP conjugates2009In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 50, no 33, p. 4731-4733Article in journal (Refereed)
    Abstract [en]

    We have improved the synthesis of a previously published luciferin-linker, used in an assay enabling rapid real-time quantification of luciferin–CPP conjugate uptake and cytosolic cargo release. We also present the synthesis of a new luciferin-linker with the same conjugation ability. Both luciferin-linkers are now available via an efficient one-pot procedure.

  • 47.
    Eiríksdóttir, Emelía
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Mager, Imre
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Lehto, Taavi
    EL Andaloussi, Samir
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Cellular Internalization Kinetics of (Luciferin-)Cell-Penetrating Peptide Conjugates2010In: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 21, no 9, p. 1662-1672Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) belong to a class of delivery vectors that have been extensively used for the cellular delivery of various, otherwise impermeable, macromolecules. However, results on the cellular internalization efficacy of CPPs obtained from various laboratories are sometimes challenging to compare because of differences in the experimental setups. Here, for the first time, the cellular uptake kinetics of eight well-established CPPs is compared in HeLa pLuc 705 cells using a recently published releasable luciferin assay. Using this assay, the kinetic behavior of cytosolic entry of these luciferin-CPP conjugates are registered in real time. Our data reveal that the uptake rate of CPPs reaches its maximum either in seconds or in tens of minutes, depending on the CPP used. Tat and higher concentrations of MAP and TP10 display fast internalization profiles that resemble the kinetic profile of membrane-permeable free luciferin. The uptake of the other peptides, pVec, penetratin, M918, and EB I, is much slower and is consistent with the reported observations of endocytosis being the predominant internalization mechanism. Additionally, to some extent, the latter CPPs can be clustered into subgroups which are based on time points when the most pronounced uptake rates are observed. This may indicate once more involvement of various (concentration dependent) mechanisms in the uptake of CPPs. In summary, the variances in the internalization profiles for the CPPs demonstrate the importance of measuring kinetics instead of only relying on simple end-point studies, and with the luciferin CPP assay, more lucid information can be retrieved when studying the internalization mechanisms of CPPs.

  • 48.
    Eiríksdóttir, Emelía
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Myrberg, Helena
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Hansen, Mats
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Cellular Uptake of Cell-Penetrating Peptides2004In: Drug Design Reviews - Online, ISSN 1567-2697, Vol. 1, no 2, p. 161-173Article in journal (Refereed)
    Abstract [en]

    Cellular machinery is protected from the surrounding by two-layer lipid membrane that is impermeable for most substances unnecessary for cellular metabolism. Unfortunately, from a cellular point of view, most new generation drugs, designed to act on gene regulation and transcription, are also considered to be unnecessary for metabolism and therefore showing poor, if any, intracellular localization. To overcome this obstacle, several chemical and physical methods have been developed, improving the uptake, but, on the other hand, also showing some unwanted side effects or limitations for in vivo applications. This dictates the continuing need for improved drug delivery and one way seems to be the relatively new class of compounds – cell-penetrating peptides (CPPs). Discovered approximately a decade ago, the content of this class is growing rapidly, containing now more than 100 compounds, which shows the intensity of work in this field. CPPs have already been shown to translocate cellular membranes in an unknown, seemingly receptor-independent and non-endocytotic manner. Moreover, they are able to deliver cargoes exceeding their own size up to 100-fold into a cellular milieu both in vitro and in vivo. The variety of different cargoes includes, but is not limited to: DNA, antisense PNA, oligonucleotides and small proteins. Recent data argues though that endocytosis is involved and contributes in some cases to the main part of the translocation. This review summarizes data on mechanisms of cell-penetrating peptides.

  • 49.
    EL Andaloussi, Samir
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Guterstam, Peter
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Assessing the delivery efficacy and internalization route of cell-penetrating peptides2007In: Nature Protocols, ISSN 1754-2189, E-ISSN 1750-2799, Vol. 2, no 8, p. 2043-2047Article in journal (Refereed)
    Abstract [en]

    Developing efficient delivery vectors for bioactive molecules is of great importance within both traditional and novel drug development, such as oligonucleotide (ON)-based therapeutics. To address delivery efficiency using cell-penetrating peptides (CPPs), we here present a protocol based on splice correction utilizing both neutral and anionic antisense ONs, either covalently conjugated via a disulfide bridge or non-covalently complexed, respectively, that generates positive readout in the form of luciferase expression. The decisive advantage of using splice correction for evaluation of CPPs is that the ON induces a biological response in contrast to traditionally used methods, for example, fluorescently labeled peptides. An emerging number of studies emphasize the role of endocytosis in translocation of CPPs, and this protocol is also utilized to determine the relative contribution of different endocytic pathways in the uptake of CPPs, which provides valuable information for future design of novel, more potent CPPs for bioactive cargoes.

  • 50.
    EL Andaloussi, Samir
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Johansson, Henrik
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Holm, Tina
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    A novel cell-penetrating peptide, M918, for efficient delivery of proteins and peptide nucleic acids2007In: Molecular Therapy, ISSN 1525-0016, E-ISSN 1525-0024, Vol. 15, no 10, p. 1820-1826Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) have attracted increasing attention in the past decade as a result of their high potential to convey various, otherwise impermeable, bioactive agents across cellular plasma membranes. Albeit different CPPs have proven potent in delivery of different cargoes, there is generally a correlation between high efficacy and cytotoxicity for these peptides. Hence, it is of great importance to find new, non-toxic CPPs with more widespread delivery properties. We present a novel CPP, M918, that efficiently translocates various cells in a non-toxic fashion. In line with most other CPPs, the peptide is internalized mainly via endocytosis, and in particular macropinocytosis, but independent of glycosaminoglycans on the cell surface. In addition, in a splice correction assay using antisense peptide nucleic acid (PNA) conjugated via a disulphide bridge to M918 (M918-PNA), we observed a dose-dependent increase in correct splicing, exceeding the effect of other CPPs. Our data demonstrate that M918 is a novel CPP that can be used to translocate different cargoes inside various cells efficiently.

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