GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (8)
  • The American Society for Biochemistry and Molecular Biology (ASBMB)  (4)
  • The American Society for Pharmacology and Experimental Therapeutics (ASPET)  (4)
  • 1
    facet.materialart.
    Unknown
    A {mu}O-Conotoxin with Improved Potency for NaV1.8 [Neurobiology] (2016)
    The American Society for Biochemistry and Molecular Biology (ASBMB)
    Details
    Publication Date: 2016-05-28
    Description: The μO-conotoxins MrVIA, MrVIB, and MfVIA inhibit the voltage-gated sodium channel NaV1.8, a well described target for the treatment of pain; however, little is known about the residues or structural elements that define this activity. In this study, we determined the three-dimensional structure of MfVIA, examined its membrane binding properties, performed alanine-scanning mutagenesis, and identified residues important for its activity at human NaV1.8. A second round of mutations resulted in (E5K,E8K)MfVIA, a double mutant with greater positive surface charge and greater affinity for lipid membranes compared with MfVIA. This analogue had increased potency at NaV1.8 and was analgesic in the mouse formalin assay.
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
    Published by The American Society for Biochemistry and Molecular Biology (ASBMB)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    Inhibitory Activity of hNaV1.7 by ProTx-II, the Membrane Link [Lipids] (2016)
    The American Society for Biochemistry and Molecular Biology (ASBMB)
    Details
    Publication Date: 2016-08-13
    Description: ProTx-II is a disulfide-rich peptide toxin from tarantula venom able to inhibit the human voltage-gated sodium channel 1.7 (hNaV1.7), a channel reported to be involved in nociception, and thus it might have potential as a pain therapeutic. ProTx-II acts by binding to the membrane-embedded voltage sensor domain of hNaV1.7, but the precise peptide channel-binding site and the importance of membrane binding on the inhibitory activity of ProTx-II remain unknown. In this study, we examined the structure and membrane-binding properties of ProTx-II and several analogues using NMR spectroscopy, surface plasmon resonance, fluorescence spectroscopy, and molecular dynamics simulations. Our results show a direct correlation between ProTx-II membrane binding affinity and its potency as an hNaV1.7 channel inhibitor. The data support a model whereby a hydrophobic patch on the ProTx-II surface anchors the molecule at the cell surface in a position that optimizes interaction of the peptide with the binding site on the voltage sensor domain. This is the first study to demonstrate that binding of ProTx-II to the lipid membrane is directly linked to its potency as an hNaV1.7 channel inhibitor.
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
    Published by The American Society for Biochemistry and Molecular Biology (ASBMB)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    A Toxoplasma Target for Acyl-protein Thioesterase Inhibitors [Membrane Biology] (2013)
    The American Society for Biochemistry and Molecular Biology (ASBMB)
    Details
    Publication Date: 2013-09-21
    Description: In eukaryotic organisms, cysteine palmitoylation is an important reversible modification that impacts protein targeting, folding, stability, and interactions with partners. Evidence suggests that protein palmitoylation contributes to key biological processes in Apicomplexa with the recent palmitome of the malaria parasite Plasmodium falciparum reporting over 400 substrates that are modified with palmitate by a broad range of protein S-acyl transferases. Dynamic palmitoylation cycles require the action of an acyl-protein thioesterase (APT) that cleaves palmitate from substrates and conveys reversibility to this posttranslational modification. In this work, we identified candidates for APT activity in Toxoplasma gondii. Treatment of parasites with low micromolar concentrations of β-lactone- or triazole urea-based inhibitors that target human APT1 showed varied detrimental effects at multiple steps of the parasite lytic cycle. The use of an activity-based probe in combination with these inhibitors revealed the existence of several serine hydrolases that are targeted by APT1 inhibitors. The active serine hydrolase, TgASH1, identified as the homologue closest to human APT1 and APT2, was characterized further. Biochemical analysis of TgASH1 indicated that this enzyme cleaves substrates with a specificity similar to APTs, and homology modeling points toward an APT-like enzyme. TgASH1 is dispensable for parasite survival, which indicates that the severe effects observed with the β-lactone inhibitors are caused by the inhibition of non-TgASH1 targets. Other ASH candidates for APT activity were functionally characterized, and one of them was found to be resistant to gene disruption due to the potential essential nature of the protein.
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
    Published by The American Society for Biochemistry and Molecular Biology (ASBMB)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Conus Venom Peptide Pharmacology [Review Articles] (2012)
    The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Details
    Publication Date: 2012-06-20
    Description: Conopeptides are a diverse group of recently evolved venom peptides used for prey capture and/or defense. Each species of cone snails produces in excess of 1000 conopeptides, with those pharmacologically characterized (~0.1%) targeting a diverse range of membrane proteins typically with high potency and specificity. The majority of conopeptides inhibit voltage- or ligand-gated ion channels, providing valuable research tools for the dissection of the role played by specific ion channels in excitable cells. It is noteworthy that many of these targets are found to be expressed in pain pathways, with several conopeptides having entered the clinic as potential treatments for pain [e.g., pyroglutamate1-MrIA (Xen2174)] and one now marketed for intrathecal treatment of severe pain [ziconotide (Prialt)]. This review discusses the diversity, pharmacology, structure-activity relationships, and therapeutic potential of cone snail venom peptide families acting at voltage-gated ion channels (-, μ-, μO-, -, -, and -conotoxins), ligand-gated ion channels (α-conotoxins, -conotoxin, ikot-ikot, and conantokins), G-protein-coupled receptors (-conopeptides, conopressins, and contulakins), and neurotransmitter transporters (-conopeptides), with expanded discussion on the clinical potential of sodium and calcium channel inhibitors and α-conotoxins. Expanding the discovery of new bioactives using proteomic/transcriptomic approaches combined with high-throughput platforms and better defining conopeptide structure-activity relationships using relevant membrane protein crystal structures are expected to grow the already significant impact conopeptides have had as both research probes and leads to new therapies.
    Print ISSN: 0031-6997
    Electronic ISSN: 1521-0081
    Topics: Chemistry and Pharmacology , Medicine
    Published by The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Identification and Characterization of ProTx-III [{mu}-TRTX-Tp1a], a New Voltage-Gated Sodium Channel Inhibitor from Venom of the Tarantula Thrixopelma pruriens [Articles] (2015)
    The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Details
    Publication Date: 2015-06-21
    Description: Spider venoms are a rich source of ion channel modulators with therapeutic potential. Given the analgesic potential of subtype-selective inhibitors of voltage-gated sodium (Na V ) channels, we screened spider venoms for inhibitors of human Na V 1.7 (hNa V 1.7) using a high-throughput fluorescent assay. Here, we describe the discovery of a novel Na V 1.7 inhibitor, μ -TRTX-Tp1a (Tp1a), isolated from the venom of the Peruvian green-velvet tarantula Thrixopelma pruriens . Recombinant and synthetic forms of this 33-residue peptide preferentially inhibited hNa V 1.7 〉 hNa V 1.6 〉 hNa V 1.2 〉 hNa V 1.1 〉 hNa V 1.3 channels in fluorescent assays. Na V 1.7 inhibition was diminished (IC 50 11.5 nM) and the association rate decreased for the C-terminal acid form of Tp1a compared with the native amidated form (IC 50 2.1 nM), suggesting that the peptide C terminus contributes to its interaction with hNa V 1.7. Tp1a had no effect on human voltage-gated calcium channels or nicotinic acetylcholine receptors at 5 μ M. Unlike most spider toxins that modulate Na V channels, Tp1a inhibited hNa V 1.7 without significantly altering the voltage dependence of activation or inactivation. Tp1a proved to be analgesic by reversing spontaneous pain induced in mice by intraplantar injection in OD1, a scorpion toxin that potentiates hNa V 1.7. The structure of Tp1a as determined using NMR spectroscopy revealed a classic inhibitor cystine knot (ICK) motif. The molecular surface of Tp1a presents a hydrophobic patch surrounded by positively charged residues, with subtle differences from other ICK spider toxins that might contribute to its different pharmacological profile. Tp1a may help guide the development of more selective and potent hNa V 1.7 inhibitors for treatment of chronic pain.
    Print ISSN: 0026-895X
    Electronic ISSN: 1521-0111
    Topics: Chemistry and Pharmacology , Medicine
    Published by The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Activating and Inhibitory Functions of WNT/{beta}-Catenin in the Induction of Cytochromes P450 by Nuclear Receptors in HepaRG Cells [Articles] (2015)
    The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Details
    Publication Date: 2015-05-01
    Description: The WNT/ β -catenin signaling pathway has been identified as an important endogenous regulator of hepatic cytochrome P450 (P450) expression in mouse liver. In particular, it is involved in the regulation of P450 expression in response to exposure to xenobiotic agonists of the nuclear receptors constitutive androstane receptor (CAR), aryl hydrocarbon receptor (AhR), and Nrf2. To systematically elucidate the effect of the WNT/ β -catenin pathway on the regulation and inducibility of major human P450 enzymes, HepaRG cells were treated with either the WNT/ β -catenin signaling pathway agonist, WNT3a, or with small interfering RNA directed against β -catenin, alone or in combination with a panel of activating ligands for AhR [2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD)], CAR [6-(4-chlorophenyl)imidazo[2,1- b ][1,3]thiazole-5-carbaldehyde- O -(3,4-dichlorobenzyl)oxime (CITCO)], pregnane X receptor (PXR) [rifampicin], and peroxisome proliferator–activated receptor (PPAR) α [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid (WY14,643)]. Assessment of P450 gene expression and enzymatic activity after downregulation or activation of the WNT/ β -catenin pathway revealed a requirement of β -catenin in the AhR-, CAR-, and PXR-mediated induction of CYP1A, CYP2B6 and CYP3A4 (for CAR and PXR), and CYP2C8 (for PXR) gene expression. By contrast, activation of the WNT/ β -catenin pathway prevented PPAR α -mediated induction of CYP1A, CYP2C8, CYP3A4, and CYP4A11 genes, suggesting a dominant-negative role of β -catenin in PPAR α -mediated regulation of these genes. Our data indicate a significant effect of the WNT/ β -catenin pathway on the regulation of P450 enzymes in human hepatocytes and reveal a novel crosstalk between β -catenin and PPAR α signaling pathways in the regulation of P450 expression.
    Print ISSN: 0026-895X
    Electronic ISSN: 1521-0111
    Topics: Chemistry and Pharmacology , Medicine
    Published by The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Comparative Analysis and Functional Characterization of HC-AFW1 Hepatocarcinoma Cells: Cytochrome P450 Expression and Induction by Nuclear Receptor Agonists [Articles] (2015)
    The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Details
    Publication Date: 2015-10-14
    Description: Enzymatic conversion of most xenobiotic compounds is accomplished by hepatocytes in the liver, which are also an important target for the manifestation of the toxic effects of foreign compounds. Most cell lines derived from hepatocytes lack important toxifying or detoxifying enzymes or are defective in signaling pathways that regulate expression and activity of these enzymes. On the other hand, the use of primary human hepatocytes is complicated by scarce availability of cells and high interdonor variability. Thus, analyses of drug metabolism and hepatotoxicity in vitro are a difficult task. The cell line HC-AFW1 was isolated from a pediatric hepatocellular carcinoma and so far has been used for tumorigenicity and chemotherapy resistance studies. Here, a comprehensive characterization of xenobiotic metabolism in HC-AFW1 cells is presented along with studies on the functionality of the most important transcriptional regulators of drug-metabolizing enzymes. Results from HC-AFW1 cells were compared with commercially available HepaRG cells and cultured primary human hepatocytes. Data show that the nuclear receptors and xenosensors AHR (aryl hydrocarbon receptor), CAR (constitutive androstane receptor), PXR (pregnane-X-receptor), NRF2 [nuclear factor (erythroid-derived 2)–like 2], and PPAR α (peroxisome proliferator–activated receptor α ) are functional in HC-AFW1 cells, comparable to HepaRG and primary cells. HC-AFW1 cells possess considerable activities of different cytochrome P450 enzymes, which, however, are lower than corresponding enzyme activities in HepaRG cells or primary hepatocytes. In summary, HC-AFW1 are a new promising tool for studying the mechanisms of the regulation of drug metabolism in human liver cells in vitro.
    Print ISSN: 0090-9556
    Electronic ISSN: 1521-009X
    Topics: Chemistry and Pharmacology , Medicine
    Published by The American Society for Pharmacology and Experimental Therapeutics (ASPET)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Analysis of the Catalytic Site of the GTPase Ran [Protein Structure and Folding] (2015)
    The American Society for Biochemistry and Molecular Biology (ASBMB)
    Details
    Publication Date: 2015-10-03
    Description: Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg2+ coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg2+ in GTPases. The Mg2+ coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis.
    Print ISSN: 0021-9258
    Electronic ISSN: 1083-351X
    Topics: Biology , Chemistry and Pharmacology
    Published by The American Society for Biochemistry and Molecular Biology (ASBMB)
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...