Endre søk
Begrens søket
1 - 30 of 30
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Adlerz, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Beckman, Marie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Holback, Sofia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Tehranian, Roya
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Cortés Toro, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Iverfeldt, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Accumulation of the amyloid precursor-like protein APLP2 and reduction of APLP1 in retinoic acid-differentiated human neuroblastoma cells upon curcumin-induced neurite retraction2003Inngår i: Brain Research. Molecular Brain Research, ISSN 0169-328X, E-ISSN 1872-6941, Vol. 119, nr 1, 62-72 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Amyloid precursor protein (APP) belongs to a conserved gene family, also including the amyloid precursor-like proteins, APLP1 and APLP2. The function of these three proteins is not yet fully understood. One of the proposed roles of APP is to promote neurite outgrowth. The aim of this study was to investigate the regulation of the expression levels of APP family members during neurite outgrowth. We observed that retinoic acid (RA)-induced neuronal differentiation of human SH-SY5Y cells resulted in increased expression of APP, APLP1 and APLP2. We also examined the effect of the NFκB, AP-1 and c-Jun N-terminal kinase inhibitor curcumin (diferuloylmethane) on the RA-induced expression levels of these proteins. We found that treatment with curcumin counteracted the RA-induced mRNA expression of all APP family members. In addition, we observed that curcumin treatment resulted in neurite retraction without any effect on cell viability. Surprisingly, curcumin had differential effects on the APLP protein levels in RA-differentiated cells. RA-induced APLP1 protein expression was blocked by curcumin, while the APLP2 protein levels were further increased. APP protein levels were not affected by curcumin treatment. We propose that the sustained levels of APP and the elevated levels of APLP2, in spite of the reduced mRNA expression, are due to altered proteolytic processing of these proteins. Furthermore, our results suggest that APLP1 does not undergo the same type of regulated processing as APP and APLP2.

  • 2.
    Adlerz, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Soomets, Ursel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. University of Tartu, Estonia.
    Holmlund, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Virland, Saade
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Iverfeldt, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Down-regulation of amyloid precursor protein by peptide nucleic acid oligomer in cultured rat primary neurons and astrocytes2003Inngår i: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 336, nr 1, 55-59 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 3.
    Eiríksdóttir, Emelía
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Myrberg, Helena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hansen, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Cellular Uptake of Cell-Penetrating Peptides2004Inngår i: Drug Design Reviews - Online, ISSN 1567-2697, Vol. 1, nr 2, 161-173 s.Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 4.
    El-Andaloussi, S.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi.
    Johansson, H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Magnusdottir, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Järver, P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Lundberg, P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    TP10, a delivery vector for decoy oligonucleotides targeting the Myc protein2005Inngår i: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 110, nr 1, 189-201 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One approach to investigate gene function, by silencing the activity of certain proteins, is the usage of double stranded decoy oligodeoxynucleotides (ds decoy ODNs). Decoy, in this sense, is ds ODNs bearing the consensus binding sequence for a DNA-binding protein. This can be used in clinical settings to attenuate the effect of overexpressed transcription factors in tumor cells. We here choose to target the oncogenic protein Myc. Since oligonucleotides are poorly internalized to cells, a cell-penetrating peptide, TP10, was coupled to the Myc decoy, using two different strategies. Either TP10 was simply mixed with ds decoy ODNs forming complexes through non-covalent electrostatic interactions, or by having a nona-nucleotide overhang in one of the decoy strands, and adding a complementary PNA sequence coupled to an NLS sequence and TP10, which could hybridize to the Myc decoy.

    By using these strategies, uptake was significantly enhanced, especially with the co-incubation approach. Interestingly, various endocytosis inhibitors had no effect on the uptake pattern, suggesting that uptake of these complexes is not mediated via endocytosis. Finally, a decreased proliferative capacity was observed when treating the neuroblastoma cell line N2a with TP10–PNA conjugate hybridized to Myc decoy compared to naked Myc decoy and untreated cells. A dose-dependent decrease in proliferation was also observed in MCF-7 cells, when using both strategies. These results suggest an alternative way to efficiently deliver ds ODNs into cells using the cell-penetrating peptide TP10 and prevent tumor growth by targeting the oncogenic protein Myc.

  • 5.
    Erlandsson, Mikael
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Metallic zinc reduction of disulfide bonds between cysteine residues in peptides and proteins2005Inngår i: International Journal of Peptide Research and Therapeutics, ISSN 1573-3149, Vol. 11, nr 4, 261-265 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of powdered metallic zinc in acidic solution for the reduction of disulfide bonds in peptides and proteins has been investigated. The method has several advantages over the traditional mereapto based reducing methods currently used; the reducing agent is readily available and inexpensive; reduction can be performed in weakly acidic solutions of water and/or acetonitrile; work up simply consists of a centrifugation step followed by pipeting the supernatant from the metal pellet, thereby greatly diminishing the risk of reoxidation as a more elaborate work up procedure could result in. As no mercapto compounds are added, there is no risk that the reducing agent will interfere in subsequent modification of the thiol functionality. Disulfides in a model peptide are reduced within 5 min in any mixture of water/acetonitrile containing 1% TFA, all disulfides in insulin is reduced within I h in any mixture of water/acetonitrile containing 5% acetic acid. To stress the convenience of the metallic zinc reduction method, the resulting thiol compound was subjected to two commonly employed reactions in peptide chemistry: Cys(Npys) directed disulfide formation (70% yield) and native chemical ligation between the reduced model peptide and Boc-Ala-p-metylthiobenzyl ester (65% yield of the ligation product plus disulfide formation between Cys and p-thiocresol).

  • 6.
    Fisher, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Soomets, Ursel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. University of Tartu, Estonia.
    Cortes Toro, Veronica
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Chilton, Lucy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Jiang, Yang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Langel, Ulo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Iverfeldt, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Cellular delivery of a double-stranded oligonucleotide NFκB decoy by hybridization to complementary PNA linked to a cell-penetrating peptide2004Inngår i: Gene Therapy, ISSN 0969-7128, E-ISSN 1476-5462, Vol. 11, 1264-1272 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The activation of nuclear factor B (NFB) is a key event in immune and inflammatory responses. In this study, a cell-penetrating transport peptide, transportan (TP) or its shorter analogue TP 10, was used to facilitate the cellular uptake of an NFB decoy. Peptide nucleic acid (PNA) hexamer or nonamer was linked to the transport peptide by a disulfide bond. NFB decoy oligonucleotide consisted of a double-stranded consensus sequence corresponding to the B site localized in the IL-6 gene promoter, 5'-GGGACTTTCCC-3', with a single-stranded protruding 3'-terminal sequence complementary to the PNA sequence was hybridized to the transport peptide–PNA construct. The ability of the transport peptide–PNA–NFB decoy complex to block the effect of interleukin (IL)-1-induced NFB activation and IL-6 gene expression was analyzed by electrophoretic mobility shift assay and reverse transcriptase-polymerase chain reaction in rat Rinm5F insulinoma cells. Preincubation with transport peptide–PNA–NFB decoy (1 M, 1 h) blocked IL-1-induced NFB-binding activity and significantly reduced the IL-6 mRNA expression. The same concentration of NFB decoy in the absence of transport peptide–PNA had no effect even after longer incubations. Our results showed that binding of the oligonucleotide NFB decoy to the nonamer PNA sequence resulted in a stable complex that was efficiently translocated across the plasma membrane.

  • 7. Fossat, Pascal
    et al.
    Dobremez, Eric
    Landry, Marc
    Kilk, Kalle
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Sibon, Igor
    Benazzouz, Rabina
    Le Masson, Gwendal
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Nagy, Frederic
    L-type calcium channels and NMDA receptors: a determinant duo for short term nociceptive plasticityManuskript (Annet vitenskapelig)
  • 8.
    Holm, Tina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Netzereab, Semharai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hansen, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Uptake of cell-penetrating peptides in yeasts2005Inngår i: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 579, nr 23, 5217-5222 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The uptake of different cell-penetrating peptides (CPPs) in two yeast species, Saccharomyces cerevisiae and Candida albicans, was studied using fluorescence HPLC-analyses of cell content. Comparison of the ability of penetratin, pVEC and (KFF)(3)K to traverse the yeast cell envelope shows that the cellular uptake of the peptides varies widely. Moreover, the intracellular degradation of the CPPs studied varies from complete stability to complete degradation. We show that intracellular degradation into membrane impermeable products can significantly contribute to the fluorescence signal. pVEC displayed highest internalizing capacity, and considering its stability in both yeast species, it is an attractive candidate for further studies.

  • 9.
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Cell penetrating peptides: mechanisms and applications2000Doktoravhandling, med artikler (Annet vitenskapelig)
  • 10.
    Jönsson, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Applications of multi-component condensations and development of polyamine synthesis on solid-phase2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Solid-phase synthesis of small non-polymeric molecules has become increasingly important as a tool in the development of pharmacologically active compounds. Of particular interest are the syntheses of compounds with low molecular weight, low polarity and a reduced flexibility of the functional groups, i.e. physiochemical properties typical for the majority of drugs currently in use.

    The first part of this thesis describes the synthesis of polycyclic structures with constrained conformation, by the application of multi-component condensations on solid-phase. The 8-azabicyclo[3.2.1]octan-3-one structure of the tropane alkaloids was synthesized on solid-phase by a modification of the well known Robinson tropinone synthesis. The 3-component reaction was performed with the amino component anchored to a solid support, consisting of polyethyleneglycol-grafted polystyrene. Treatment of the primary amine with 1,3-acetonedicarboxylic acid and excess of succinaldehyde, resulted in high purity of the corresponding tropane derivative. Further derivatization of the resin-bound tropane derivative was performed by reduction of the keto-group and acylation of the hydroxyl-group.

    The oxygen-bridged tetrahydropyridones are relatively complex polycyclic structures, which previously have been synthesized in solution by condensation of primary amines, coumarin-3-carboxylic acid and ketones. In the evaluation of a solid-phase approach of this 3-component condensation, several members of this class of compounds were synthesized with the amine anchored to a solid support. The yield and purity of the products were dependent on the ketones used in the reaction, but the expected products were obtained using both acyclic and cyclic ketones and substituted acetophenones.

    The second part of this thesis describes the development of a solid-phase polyamine synthesis. The polyamines are a class of compounds with a wide range of pharmacological and physiological effects, which are constituents in many types of venoms of wasps and spiders. Synthesis of polyamines in homogenous solution is accompanied with several problems concerning selectivity, work-up and yield. By employing a solid-phase approach, a rapid and convenient method for synthesis of polyamines is achieved. In the developed protocol, acid labile benzhydryls are used as amino-protecting groups. The polyamine backbone is assembled sequentially by reductive alkylation of the protected secondary amine with Fmoc-amino aldehydes. The protecting groups allow the use of excess of aldehyde, to avoid underivatized amines, without the risking dialkaylation of the amines, which occurs during reductive alkylations of primary amines with unhindered aliphatic aldehydes. The versatility of the method is displayed by a convenient synthesis of four analogues of a wasp toxin, philanthotoxin.

  • 11.
    Jönsson, Daniel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Erlandsson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Undén, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Solid-phase synthesis of oxygen-bridged tetrahydropyridones2001Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 42, nr 39, 6953-6956 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A solid-phase approach for the synthesis of oxygen-bridged tetrahydropyridones has been developed. A diamine is attached to Trt-Cl resin and condensed with different aliphatic or aromatic ketones and coumarin-3-carboxylic acid for 20 h and cleaved with 5% TFA in DCM, resulting in tri or tetracyclic products in moderate to high yield.

  • 12.
    Kihlmark, Madeleine
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik. Södertörn University College, Sweden.
    Rustum, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Södertörn University College, Sweden.
    Eriksson, Charlotta
    Beckman, Marie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Iverfeldt, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hallberg, Einar
    Correlation between nucleocytoplasmic transport and caspase–3-dependent dismantling of nuclear pores during apoptosis2004Inngår i: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 293, nr 2, 346-356 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During apoptosis (also called programmed cell death), the chromatin condenses and the DNA is cleaved into oligonucleosomal fragments. Caspases are believed to play a major role in nuclear apoptosis. However, the relation between dismantling of nuclear pores, disruption of the nucleocytoplasmic barrier, and nuclear entry of caspases is unclear. We have analyzed nuclear import of the green fluorescent protein fused to a nuclear localization signal (GFP-NLS) in tissue culture cells undergoing apoptosis. Decreased nuclear accumulation of GFP-NLS could be detected at the onset of nuclear apoptosis manifested as dramatic condensation and redistribution of chromatin toward the nuclear periphery. At this step, dismantling of nuclear pores was already evident as indicated by proteolysis of the nuclear pore membrane protein POM121. Thus, disruption of nuclear compartmentalization correlated with early signs of nuclear pore damage. Both these events clearly preceded massive DNA fragmentation, detected by TUNEL assay. Furthermore, we show that in apoptotic cells, POM121 is specifically cleaved at aspartate-531 in its large C-terminal portion by a caspase-3-dependent mechanism. Cleavage of the C-terminal portion of POM121, which is adjoining the nuclear pore complex, is likely to disrupt interactions with other nuclear pore proteins affecting the stability of the pore complex. A temporal correlation of apoptotic events supports a model where caspase-dependent disassembly of nuclear pores and disruption of the nucleocytoplasmic barrier paves the way for nuclear entry of caspases and subsequent activation of CAD-mediated DNA fragmentation.

  • 13.
    Kilk, Kalle
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    EL Andaloussi, Samir
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Järver, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Meikas, Anne
    Valkna, Andres
    Bartfai, Tamas
    Kogerman, Priit
    Metsis, Madis
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Evaluation of transportan 10 in PEI mediated plasmid delivery assay2005Inngår i: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 103, nr 2, 511-23 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are novel high-capacity delivery vectors for different bioactive cargoes. We have evaluated the CPP transportan 10 (TP10) as a delivery vector in different in vitro plasmid delivery assays. Tested methods include: TP10 crosslinked to a plasmid via a peptide nucleic acid (PNA) oligomer, TP10 conjugation with polyethyleneimine (PEI), and addition of unconjugated TP10 to standard PEI transfection assay. We found that without additional DNA condensing agents, TP10 has poor transfection abilities. However, the presence of TP10 increases the transfection efficiency several folds compared to PEI alone. At as low concentrations as 0.6 nM, TP10–PNA constructs were found to enhance plasmid delivery up to 3.7-fold in Neuro-2a cells. Interestingly, the transfection efficiency was most significant at low PEI concentrations, allowing reduced PEI concentration without loss of gene delivery. No increase in cytotoxicity due to TP10 was observed and the uptake mechanism was determined to be endocytosis, as previously reported for PEI mediated transfection. In conclusion, TP10 can enhance PEI mediated transfection at relatively low concentrations and may help to develop future gene delivery systems with reduced toxicity.

  • 14.
    Kilk, Kalle
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Tartu University, Estonia.
    Elmquist, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Saar, Külliki
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Pooga, Margus
    Tiit, Land
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Bartfai, Tamas
    Soomets, Ursel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Tartu University, Estonia.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Targeting of antisense PNA oligomers to human galanin receptor type 1 mRNA2004Inngår i: Neuropeptides, ISSN 0143-4179, E-ISSN 1532-2785, Vol. 38, nr 5, 316-324 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we have targeted positions 18–38 of the human galanin receptor type 1 (GalR1) mRNA coding sequence with different peptide nucleic acid (PNA) oligomers. This region has previously been shown to be a good antisense region and therefore we aimed to identify the subregions and/or thermodynamic parameters determining the antisense efficacy. Nine different PNA oligomers were conjugated to a cell-penetrating peptide, transportan, to enhance their cellular uptake. Concentration-dependent down-regulation of GalR1 protein expression in human melanoma cell line Bowes was measured by radioligand binding assay. No reduction of GalR1 mRNA level was observed upon PNA treatment, thus, the effect was concluded to be translational arrest. Judging from the EC50 values, antisense PNA oligomers targeting regions 24–38 (EC50 = 70 nM) or 27–38 (EC50 = 80 nM) were the most potent suppressors of protein expression. No parameter predicted by M-fold algorithm was found to correlate with the measured antisense activities. Presence of some subregions was found not to increase antisense efficiency of PNA. Presence of a short unpaired triplet between nucleotides 33 and 35 in the target region was, on the other hand, found to be the most critical for efficient GalR1 down-regulation. Thus, the results are of high impact in designing antisense oligomers. Specific results of this study demonstrate 20-fold more efficient antisense down-regulation of GalR1 as achieved before.

  • 15.
    Kilk, Kalle
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. University of Tartu, Estonia.
    Magzoub, Mazin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Pooga, Margus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Estonian Biocenter, Estonia.
    Eriksson, L. E. Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Cellular internalization of a cargo complex with a novel peptide derived from the third helix of the islet-1 homeodomain: Comparison with the penetratin peptide2001Inngår i: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 12, nr 6, 911-916 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellular translocation into a human Bowes melanoma cell line was investigated and compared for penetratin and pIsl, two peptides that correspond to the third helices of the related homeodomains, from the Antennapedia transcription factor of Drosophila and the rat insulin-1 gene enhancer protein, respectively. Both biotinylated peptides internalized into the cells with similar efficacy, yielding an analogous intracellular distribution. When a large cargo protein, 63 kDa avidin, was coupled to either peptide, efficient cellular uptake for both the peptide−protein complexes was observed. The interactions between each peptide and SDS micelles were studied by fluorescence spectroscopy and acrylamide quenching of the intrinsic tryptophan (Trp) fluorescence. Both peptides interacted strongly and almost identically with the membrane mimicking environment. Compared to penetratin, the new transport peptide pIsl has only one Trp residue, which simplifies the interpretation of the fluorescence spectra and in addition has a native Cys residue, which may be used for alternative coupling reactions of cargoes of different character.

  • 16.
    Lindgren, Maria
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    On cell-penetrating peptides and cell-junction interactions2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Cell-penetrating peptides have the remarkable ability to carry hydrophilic macromolecules over the cellular membrane in an energy and protein independent manner. To synthesise and characterise new variants of cell-penetrating peptides, mainly aimed at finding analogues with minimised side effects and efficient cellular delivery, was one of the two main objectives of this thesis. The other principal objective was to study cell-junction interactions by the protein vascular endothelial cadherin. In addition, a study where the two objectives were combined was aimed at investigating the possibility of utilising cell-penetrating peptides for trans-barrier delivery.

    In order to gain more information about the cell-junction interactions of vascular endothelial cadherin, monoclonal antibodies directed to the extracellular domain were tested for their activity. Three of the antibodies were able to increase paracellular permeability, inhibit VE-cadherin reorganisation, and block angiogenesis in vitro. In addition, epitope mapping of the antibodies located their binding sequences to EC1, EC3 and EC4 of VE-cadherin ectodomain. These results support the concept that VE-cadherin protein sequence consists of multiple biologically important domains.

    The aim of paper II was to compare transportan, developed by our group, with the first discovered cell-penetrating peptide, penetratin. Novel analogues were synthesised and tested for cellular uptake and also in molecular modelling. The transportan analogues were different chimeric constructs, elaborating with the two different parts of the peptide, while the penetratin analogues were modifications of the original sequence. Furthermore, the translocation ability of fluorescently labelled parent peptides, transportan and penetratin, were quantitatively measured. The results imply that the two peptides and their analogues do not enter the cells by the same mechanism.

    Since it was clear that the mastoparan part of transportan was necessary for cellular penetration while the galanin part was more adaptable, several shorter analogues were synthesised in order to define the essential sequence for transportan penetration. In order to reduce the unwanted side effects, the biological effects of transportan and its deletion analogues were studied by GTPase activity measurements. It was concluded that the deletion of six amino acids from the N-terminus did not significantly impair the cell penetration, while truncation of the C-terminus or in the middle of the peptide decreased or even abolished the cellular uptake of transportan.

    pVEC is a new type of cell-penetrating peptides derived from the murine sequence of VE-cadherin. In this study we show that pVEC is a non-toxic, efficient cell-penetrating peptide that can be used for cellular delivery of both PNA and large proteins, such as streptavidin. The uptake of pVEC was quantified, by direct fluorescence labelling in both mouse and human endothelial cell lines. Furthermore, no significant effect could be detected on the parent protein VE-cadherins cell-junction clustering.

    In paper V it is shown that transportan and the analogue, transportan 10, enter and pass across a human colon cancer Caco-2 epithelial cell layer. However, the peptides decreased the trans-epithelial electric resistance of the barrier model, but not the dextran passage to the same extent. Taken together, these data demonstrate that transportan and transportan 10 are conveyed over the epithelial cell layer, mainly by the transcellular pathway, but at higher peptide concentration, the paracellular pathway may contribute to the passage. To conclude, cell-penetrating peptides may be a new possible strategy for drug delivery over a tight junction barrier, such as the blood-brain barrier. 

  • 17.
    Lundberg, Pontus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Magzoub, Mazin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Lindberg, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Jarvet, Jüri
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Eriksson, L. E. Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Cell membrane translocation of the N-terminal (1-28) part of the prion protein2002Inngår i: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 299, nr 1, 85-90 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The N-terminal (1-28) part of the mouse prion protein (PrP) is a cell penetrating peptide, capable of transporting large hydrophilic cargoes through a cell membrane. Confocal fluorescence microscopy shows that it transports the protein avidin (67 kDa) into several cell lines. The (1-28) peptide has a strong tendency for aggregation and P-structure formation, particularly in interaction with negatively charged phospholipid membranes. The findings have implications for how prion proteins with uncleaved signal peptides in the N-termini may enter into cells, which is important for infection. The secondary structure conversion into beta-structure may be relevant as a seed for the conversion into the scrapie (PrPSc) form of the protein and its arnyloidic transformation.

  • 18.
    Lundström, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Lu, Xiaoying
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Bartfai, Tamas
    Important pharmacophores for binding to galanin receptor 22005Inngår i: Neuropeptides, ISSN 0143-4179, E-ISSN 1532-2785, Vol. 39, nr 3, 169-171 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Galanin(2–11) has been introduced as a receptor subtype selective ligand for the GalR2 subtype of the galanin receptors, and has gained use in pharmacological studies of galaninergic signaling in the past two years. By introducing l-Ala substitutions in the galanin(2–11) sequence, we have examined the amino acid residues which are of importance for binding to the GalR2 receptor. Our study shows that Trp2, Asn5, Gly8 and Tyr9 are of great importance for high affinity binding. When placed in an α-helical conformation, the side chains of these residues are, with the exception of Tyr9, displayed on the same “side” of the peptide. This information is useful in the rational design of non-peptide type GalR2 receptor ligands.

  • 19.
    Lundström, Linda
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Sollenberg, Ulla
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Brewer, Ariel
    Kouya, Poli Francois
    Zheng, Kang
    Xu, Xiao-Jun
    Xia, Sheng
    Robinson, John K.
    Wiesenfeld-Hallin, Zsuzsanna
    Xu, Zhi-Qing
    Hökfelt, Tomas
    Bartfai, Tamas
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    A galanin receptor subtype 1 specific agonist2005Inngår i: International Journal of Peptide Research and Therapeutics, ISSN 1573-3904, Vol. 11, nr 1, 17-27 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chimeric peptide M617, galanin(1–13)-Gln14-bradykinin(2–9)amide, is a novel galanin receptor ligand with increased subtype specificity for GalR1 and agonistic activity in cultured cells as well as in vivo. Displacement studies on cell membranes expressing hGalR1 or hGalR2 show the presence of a high affinity binding site for M617 on GalR1 (K i=0.23±.12 nM) while lower affinity was seen towards GalR2 (K i=5.71±1.28 nM) resulting in 25-fold specificity for GalR1. Activation of GalR1 upon stimulation with M617 is further confirmed by internalization of a GalR1-EGFP conjugate. Intracellular signaling studies show the ability of M617 to inhibit forskolin stimulated cAMP formation with 57% and to produce a 5-fold increase in inositol phosphate (IP) accumulation. Agonistic effects on signal transduction are shown on both receptors studied after treatment with M617 in the presence of galanin. In noradrenergic locus coeruleus neurons, M617 induces an outward current even in the presence of TTX plus Ca2+, high Mg2+, suggesting a postsynaptic effect. Intracerebroventricular (i.c.v.) administration of M617 dose-dependently stimulates food uptake in rats while, in contrast, M35 completely fails to affect the feeding behavior. Spinal cord flexor reflex is facilitated by intrathecal (i.t.) administration of M617 as well as galanin with no significant change upon pre-treatment with M617. M617 dose dependently antagonizes the spinal cord hyperexcitablility induced by C-fiber conditioning stimulus and does neither enhance nor antagonize the effect of galanin. These data demonstrate a novel galanin receptor ligand with subtype specificity for GalR1 and agonistic activity, both in vitro and in vivo.

  • 20.
    Magzoub, Mazin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Kilk, Kalle
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Eriksson, L. E. Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Gräslund, Astrid
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Interaction and structure induction of cell-penetrating peptides in the presence of phospholipid vesicles2001Inngår i: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1512, nr 1, 77-89 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Certain short peptides, which are able to translocate across cell membranes with a low lytic activity, can be useful as carriers (vectors) for hydrophilic molecules. We have studied three such cell penetrating peptides: pAntp (‘penetratin’), pIsl and transportan. pAntp and pIsl originate from the third helix of homeodomain proteins (Antennapedia and Isl-1, respectively). Transportan is a synthetic chimera (galanin and mastoparan). The peptides in the presence of various phospholipid vesicles (neutral and charged) and SDS micelles have been characterized by spectroscopic methods (fluorescence, EPR and CD). The dynamics of pAntp were monitored using an N-terminal spin label. In aqueous solution, the CD spectra of the three peptides show secondary structures dominated by random coil. With phospholipid vesicles, neutral as well as negatively charged, transportan gives up to 60% α-helix. pAntp and pIsl bind significantly only to negatively charged vesicles with an induction of around 60% β-sheet-like secondary structure. With all three peptides, SDS micelles stabilize a high degree of α-helical structure. We conclude that the exact nature of any secondary structure induced by the membrane model systems is not directly correlated with the common transport property of these translocating peptides.

  • 21.
    Magzoub, Mazin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Lundberg, Pontus
    Oglecka, Kamila
    Eriksson, L. E. Göran
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Gräslund, Astrid
    Cell-penetration and membrane leakage by peptides derived from the N-termini of prion proteinsManuskript (Annet vitenskapelig)
  • 22.
    Mäe, Maarja
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Tallinn University of Technology, Estonia.
    Myrberg, Helena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Jiang, Yang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Paves, Heiti
    Valkna, Andres
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Internalisation of cell-penetrating peptides into tobacco protoplasts2005Inngår i: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1669, nr 2, 101-107 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cells are protected from the surrounding environment by plasma membrane which is impenetrable for most hydrophilic molecules. In the last 10 years cell-penetrating peptides (CPPs) have been discovered and developed. CPPs enter mammalian cells and carry cargo molecules over the plasma membrane with a molecular weight several times their own. Known transformation methods for plant cells have relatively low efficiency and require improvement. The possibility to use CPPs as potential delivery vectors for internalisation in plant cells has been studied in the present work. We analyse and compare the uptake of the fluorescein-labeled CPPs, transportan, TP10, penetratin and pVEC in Bowes human melanoma cells and Nicotiana tabacum cultivar (cv.) SR-1 protoplasts (plant cells without cell wall). We study the internalisation efficiency of CPPs with fluorescence microscopy, spectrofluorometry and fluorescence-activated cell sorter (FACS). All methods indicate, for the first time, that these CPPs can internalise into N. tabacum cv. SR-1 protoplasts. Transportan has the highest uptake efficacy among the studied peptides, both in mammalian cells and plant protoplast. The internalisation of CPPs by plant protoplasts may open up a new effective method for transfection in plants.

  • 23.
    Palm, Caroline
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Netzereab, Semharai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Quantitatively determined uptake of cell-penetrating peptides in non-mammalian cells with an evaluation of degradation and antimicrobial effects2006Inngår i: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 27, nr 7, 1710-1716 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are carriers developed to improve mammalian cell uptake of important research tools such as antisense oligonucleotides and short interfering RNAs. However, the data on CPP uptake into non-mammalian cells are limited. We have studied the uptake and antimicrobial effects of the three representative peptides penetratin (derived from a non-mammalian protein), MAP (artificial peptide) and pVEC (derived from a mammalian protein) using fluorescence HPLC in four common model systems: insect cells (Sfg), gram-positive bacteria (Bacillus megaterium), gram-negative bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae). We demonstrate that non-mammalian cells internalize CPPs and a comparison of the uptake of the peptides show that the intracellular concentration and degradation of the peptides varies widely among organisms. In addition, these CPPs showed antimicrobial activity.

  • 24.
    Pooga, Margus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Estonian Biocentre, Estonia.
    Kut, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Kihlmark, Madeleine
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Fernaeus, Sandra
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Raid, Raivo
    Land, Tiit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Hallberg, Einar
    Bartfai, Tamas
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi. Scripps Research Institute, California.
    Cellular translocation of proteins by transportan2001Inngår i: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 15, nr 6, 1451-1453 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proteins with molecular masses ranging from 30 kDa. (green fluorescent protein, GFP) to 150 kDa (monoclonal and polyclonal antibodies) were coupled to the cellular translocating peptide transportan. We studied the ability of the resulting protein-peptide constructs to penetrate into Bowes melanoma, BRL, and COS-7 cells. After 0.5-3 h incubation with recombinant GFP coupled to transportan, most of the GFP fluorescence was found in intracellular membranes of BRL and COS-7 cells, which suggests that transportan could internalize covalently linked proteins of about 30 kDa in a folded state. Transportan could internalize covalently coupled molecules of even larger size; that is, avidin and antibodies, (up to 150 kDa). The covalent bond between the transport peptide and its cargo is not obligatory because streptavidin was translocated into the cells within 15 min as a noncovalent complex with biotinylated transportan. Inside the cells, the delivered streptavidin was first located mainly in close proximity to the plasma membrane and was later distributed to the perinuclear region. Most of the internalized streptavidin was confined to vesicular structures, but a significant fraction of the protein was distributed in the cytoplasm. Our data suggest that transportan can deliver proteins and other hydrophilic macromolecules into intact mammalian cells, and this finding demonstrates good potential as powerful cellular delivery vector for scientific and therapeutic purposes.

  • 25.
    Rosenthal, Katri
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Erlandsson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Undén, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    4-(3-Hydroxy-4-methylpentyl)phenylacetic acid as a new linker for the solid phase synthesis of peptides with Boc chemistry1999Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 40, nr 2, 377-380 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The anchoring the first amino acid in Boc chemistry to a 4-(3-hydroxy-4-methylpentyl)phenylacetic acid linker is described and compared to the conventional Pam resin. The peptidyl-4-(4-methyl-3-pentoxy)phenylacetamide linkage is slightly more stable to TFA than the Pam linker but in contrast to the Pam linker stable to cleavage of benzylic protective groups with TFMSA/DMS/TFA mixtures. This allows a mild and convenient two step deprotection procedure using the “low TFMSA-high HF”. In HF this new linker reacts preferentially in an intramolecular reaction forming a tetrahydronaphthalene derivative.

  • 26.
    Rosenthal-Aizman, Katri
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Svensson, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Undén, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Self-assembling peptide nanotubes from enantiomeric pairs of cyclic peptides with alternating D and L amino acid residues2004Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, nr 11, 3372-3373 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cyclic peptides with alternating d- and l-amino acid residues containing tert-leucine residues in every second position can form peptide nanotubes only when both enantiomers of the peptide are present in the solution. These results strongly indicate the formation of peptide nanotubes that assemble with one enantiomer in every second position, thereby forming a lamellar structure.

  • 27.
    Saar, Külliki
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Ligands and receptor-derived peptides: approaches to influence signalling via galanin receptors2001Doktoravhandling, med artikler (Annet vitenskapelig)
  • 28.
    Samuelsson, Malin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Fisher, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Iverfeldt, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    β-Amyloid and interleukin-1β induce persistent NF-κB activation in rat primary glial cells2005Inngår i: International Journal of Molecular Medicine, ISSN 1107-3756, E-ISSN 1791-244X, Vol. 16, nr 3, 449-453 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An increasing body of evidence suggests that β-amyloid (Aβ) and activated glial cells play a crucial part in the pathogenesis of Alzheimer's disease (AD). Activated glial cells surrounding the senile plaques, formed by Aβ peptides, have been proposed to promote neurodegeneration by producing putatively toxic factors, including the inflammatory cytokine interleukin-1β (IL-1β). Elevated levels of both IL-1β and activated nuclear factor κB (NF-κB), a key transcription factor regulating a wide variety of inflammatory genes, have been found in the brains of AD patients. In this study, we have investigated the ability of the Aβ(25-35) peptide and IL-1β, either alone or together, in activating NF-κB in glial cells. Mixed primary glial cells from rat were treated with IL-1β and/or Aβ(25-35), and NF-κB binding activity was analyzed by electophoretic mobility shift assay. We observed that the induction of NF-κB binding activity induced by either IL-1β or Aβ(25-35) showed a peak at 30 min, and significantly declined after 2 h. The induced NF-κB activation persisted after 24 h and even seemed to increase in cells treated with Aβ(25-35). The activation of NF-κB by Aβ(25-35) was shown to be dose-dependent. In addition, Aβ(25-35) potentiated the effect of IL-1β in a dose-dependent manner when co-stimulating the cells. The potentiating effect of Aβ(25-35) on IL-1β-induced NF-κB binding activity was observed after 30 min, 2 h and 24 h, and did not significantly differ over time. A possible explanation is that when glial cells are stimulated by inflammatory factors in the presence of Aβ peptides or senile plaques, the NF-κB negative feedback regulation is no longer functional.

  • 29.
    Ståhl, Annelie
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Nilsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Lundberg, Pontus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Bhushan, Shashi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Biverståhl, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Moberg, Per
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Morisett, Magali
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Vener, Alexander
    Mäler, Lena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Glaser, Elzbieta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Two Novel Targeting Peptide Degrading Proteases, PrePs, in Mitochondria and Chloroplasts, so Similar and Still Different2005Inngår i: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 349, nr 4, 847-860 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two novel metalloproteases from Arabidopsis thaliana, termed AtPrePI and AtPrePII, were recently identified and shown to degrade targeting peptides in mitochondria and chloroplasts using an ambiguous targeting peptide. AtPrePI and AtPrePII are classified as dually targeted proteins as they are targeted to both mitochondria and chloroplasts. Both proteases harbour an inverted metal binding motif and belong to the pitrilysin subfamily A. Here we have investigated the subsite specificity of AtPrePI and AtPrePII by studying their proteolytic activity against the mitochondrial F1β pre-sequence, peptides derived from the F1β pre-sequence as well as non-mitochondrial peptides and proteins. The degradation products were analysed, identified by MALDI-TOF spectrometry and superimposed on the 3D structure of the F1β pre-sequence. AtPrePI and AtPrePII cleaved peptides that are in the range of 10 to 65 amino acid residues, whereas folded or longer unfolded peptides and small proteins were not degraded. Both proteases showed preference for basic amino acids in the P1 position and small, uncharged amino acids or serine residues in the P1P′1

    position. Interestingly, both AtPrePI and AtPrePII cleaved almost exclusively towards the ends of the α-helical elements of the F1β pre-sequence. However, AtPrePI showed a preference for the N-terminal amphiphilic α-helix and positively charged amino acid residues and degraded the F1β pre-sequence into 10–16 amino acid fragments, whereas AtPrePII did not show any positional preference and degraded the F1β pre-sequence into 10–23 amino acid fragments. In conclusion, despite the high sequence identity between AtPrePI and AtPrePII and similarities in cleavage specificities, cleavage site recognition differs for both proteases and is context and structure dependent.

  • 30.
    Tehranian, Roya
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    On inflammatory cytokines and β-amyloid peptides in acute and chronic neurodegeneration2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Insults to the brain as well as neurodegenerative diseases are known to elicit inflammatory responses. Inflammation in the brain can on one hand initiate processes that are harmful to the injured tissue and exacerbate the damage, leading to neuronal degeneration and glial activation, and on the other hand activate processes that may be necessary for repair mechanisms and regeneration. Among the mediators of inflammatory response in the brain are the inflammatory cytokines. The most studied are interleukin-1 (IL)-1, IL-6 and tumor necrosis factor-alfa (TNF- ). Although the expression of these cytokines is low under normal conditions in the brain, it can be rapidly induced in response to injury.

    This thesis is focused on the role of IL-1 family of proteins, namely the agonists IL-1 and and the endogenous IL-1 receptor antagonist (IL-1ra), and IL-6, in different experimental models of neurodegeneration. In order to study the role of IL-1 family of proteins during inflammation in an excitotoxic model of brain injury, adult rats were injected systemically with kainic acid, a glutamate analogue known to evoke seizures and neuronal cell loss in the rat brain. Using the combined technique of reverse-transcriptase coupled to PCR (RT-PCR) and in situ hybridization histochemistry, an upregulation of microglial mRNA expression of IL-1 and IL-1ra was found in brain areas with neuronal degeneration, such as the hippocampus and amygdala. IL-1ra mRNA was induced at later time point than IL-1 mRNA and was identified as the transcript coding for the secreted isoform of IL-1ra. This suggets that upregulation of these cytokines is a part of an inflammtory response associated with neurodegeneration and that the effect of IL-1 may be regulated by the expression of IL-1ra in this model. In order to study the role played by IL-1 in inflammation associated with traumatic brain injury (TBI), an experimental model was inflicted on transgenic mice. Heterozygous overexpression of the human secreted isoform of IL-1ra in the brain decreased the induction of IL-1 and IL-6 after injury. Using a neurological severity score (NSS), which mainly reflects motor recovery, we found that these animals recovered faster as compared to their non-transgenic littermates.

    Furthermore, the proinflammatory cytokine expression was studied by RT-PCR in a mouse model of Alzheimer's disease (AD). The Tg2576 mice strain overexpress -amyloid (A ) precursor protein with the "Swedish" mutation linked to familiar AD and exhibits some of the neuropathology associated with AD, such as the deposition of insoluble extracellular amyloid fibrils (amyloid plaques) in specific brain regions. Analysis of expression of cytokines in the brain of Tg2576 mice revealed an early induction of IL-6 in the hippocampus and cerebral cortex that precedes the formation of amyloid plaques. This finding is interesting since in AD brain IL-6 is detected in microglia in the vicinity of diffuse plaques (non-fibrillar). Thus, the result from this study suggests that increased IL-6 expression may be an early event in AD inflammation.

    The main constituent of amyloid plaques in the AD brain is the A peptide. The synthetic peptide A (25-35), a neurotoxic fragment of the full-length A peptide was studied for its ability to activate glial cells in culture and induce cytokine expression, as well as for its influence on G-protein coupled signalling in rat brain tissue. A (25-35) treatment of mixed astroglial cultures resulted in marked induction of IL-6 mRNA as studied by RT-PCR. Together with the results from the Tg2576 mice these results suggest a role for IL-6 in AD pathogenesis.

    Alteration in cellular signal transduction has also been reported in AD brain. A (25-35) was shown to stimulate the enzymatic activities of GTPase and adenylate cyclase in membrane preparations from rat hippocampus and cerebral cortex, which are particularly affected regions in AD brain. Using Pertussis toxin treated membranes, the stimulatory effect on GTPase activity was totally abolished, suggesting that Gi/Go type of G-proteins mediated the effect of the A peptide. 

1 - 30 of 30
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf