The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Dalia Gordon - One of the best experts on this subject based on the ideXlab platform.
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the specificity of av3 Sea Anemone Toxin for arthropods is determined at linker di ss2 s6 in the pore module of target sodium channels
Biochemical Journal, 2014Co-Authors: Maya Gur Barzilai, Yehu Moran, Roy Kahn, Dalia Gordon, Noa Regev, Michael GurevitzAbstract:Av3 is a peptide neuroToxin from the Sea Anemone Anemonia viridis that shows specificity for arthropod voltage-gated sodium channels (Na v s). Interestingly, Av3 competes with a scorpion α-Toxin on binding to insect Na v s and similarly inhibits the inactivation process, and thus has been classified as ‘receptor site-3 Toxin’, although the two peptides are structurally unrelated. This raises questions as to commonalities and differences in the way both Toxins interact with Na v s. Recently, site-3 was partly resolved for scorpion α-Toxins highlighting S1–S2 and S3–S4 external linkers at the DIV voltage-sensor module and the juxtaposed external linkers at the DI pore module. To uncover channel determinants involved in Av3 specificity for arthropods, the Toxin was examined on channel chimaeras constructed with the external linkers of the mammalian brain Na v 1.2a, which is insensitive to Av3, in the background of the Drosophila DmNa v 1. This approach highlighted the role of linker DI/SS2–S6, adjacent to the channel pore, in determining Av3 specificity. Point mutagenesis at DI/SS2–S6 accompanied by functional assays highlighted Trp 404 and His 405 as a putative point of Av3 interaction with DmNa v 1. His 405 conservation in arthropod Na v s compared with tyrosine in vertebrate Na v s may represent an ancient substitution that explains the contemporary selectivity of Av3. Trp 404 and His 405 localization near the membrane surface and the hydrophobic bioactive surface of Av3 suggest that the Toxin possibly binds at a cleft by DI/S6. A partial overlap in receptor site-3 of both Toxins nearby DI/S6 may explain their binding competition capabilities.
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molecular analysis of the Sea Anemone Toxin av3 reveals selectivity to insects and demonstrates the heterogeneity of receptor site 3 on voltage gated na channels
Biochemical Journal, 2007Co-Authors: Yehu Moran, Lior Cohen, Roy Kahn, Izhar Karbat, Dalia Gordon, Michael GurevitzAbstract:Av3 is a short peptide Toxin from the Sea Anemone Anemonia viridis shown to be active on crustaceans and inactive on mammals. It inhibits inactivation of Navs (voltage-gated Na+ channels) like the structurally dissimilar scorpion α-Toxins and type I Sea Anemone Toxins that bind to receptor site-3. To examine the potency and mode of interaction of Av3 with insect Navs, we established a system for its expression, mutagenized it throughout, and analysed it in toxicity, binding and electrophysiological assays. The recombinant Av3 was found to be highly toxic to blowfly larvae (ED50=2.65±0.46 pmol/100 mg), to compete well with the site-3 Toxin LqhαIT (from the scorpion Leiurus quinquestriatus) on binding to cockroach neuronal membranes (Ki=21.4±7.1 nM), and to inhibit the inactivation of Drosophila melanogaster channel, DmNav1, but not that of mammalian Navs expressed in Xenopus oocytes. Moreover, like other site-3 Toxins, the activity of Av3 was synergically enhanced by ligands of receptor site-4 (e.g. scorpion β-Toxins). The bioactive surface of Av3 was found to consist mainly of aromatic residues and did not resemble any of the bioactive surfaces of other site-3 Toxins. These analyses have portrayed a Toxin that might interact with receptor site-3 in a different fashion compared with other ligands of this site. This assumption was corroborated by a D1701R mutation in DmNav1, which has been shown to abolish the activity of all other site-3 ligands, except Av3. All in all, the present study provides further evidence for the heterogeneity of receptor site-3, and raises Av3 as a unique model for design of selective anti-insect compounds.
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expression and mutagenesis of the Sea Anemone Toxin av2 reveals key amino acid residues important for activity on voltage gated sodium channels
Biochemistry, 2006Co-Authors: Yehu Moran, Lior Cohen, Roy Kahn, Izhar Karbat, Dalia Gordon, Michael GurevitzAbstract:: Type I Sea Anemone Toxins are highly potent modulators of voltage-gated Na-channels (Na(v)s) and compete with the structurally dissimilar scorpion alpha-Toxins on binding to receptor site-3. Although these features provide two structurally different probes for studying receptor site-3 and channel fast inactivation, the bioactive surface of Sea Anemone Toxins has not been fully resolved. We established an efficient expression system for Av2 (known as ATX II), a highly insecticidal Sea Anemone Toxin from Anemonia viridis (previously named A. sulcata), and mutagenized it throughout. Each Toxin mutant was analyzed in toxicity and binding assays as well as by circular dichroism spectroscopy to discern the effects derived from structural perturbation from those related to bioactivity. Six residues were found to constitute the anti-insect bioactive surface of Av2 (Val-2, Leu-5, Asn-16, Leu-18, and Ile-41). Further analysis of nine Av2 mutants on the human heart channel Na(v)1.5 expressed in Xenopus oocytes indicated that the bioactive surfaces toward insects and mammals practically coincide but differ from the bioactive surface of a structurally similar Sea Anemone Toxin, Anthopleurin B, from Anthopleura xanthogrammica. Hence, our results not only demonstrate clear differences in the bioactive surfaces of Av2 and scorpion alpha-Toxins but also indicate that despite the general conservation in structure and importance of the Arg-14 loop and its flanking residues Gly-10 and Gly-20 for function, the surface of interaction between different Sea Anemone Toxins and Na(v)s varies.
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Toxin iii from leiurus quinquestriatus quinquestriatus a specific probe for receptor site 3 on insect sodium channels
Insect Biochemistry and Molecular Biology, 1997Co-Authors: Sandrine Cestele, Dalia Gordon, Charles Kopeyan, H RochatAbstract:Scorpion Toxin Lqq III binds to a single class of high affinity (Kd = 72 ± 19 pM) and low capacity (Bmax = 2.5 ± 0.2 pmol/mg) binding sites in cockroach neuronal membranes. Its binding was inhibited by LqhαIT (IC50 = 80 ± 30 pM) and Sea-Anemone Toxin ATX II (IC50 = 2.5 ± 0.3 nM), suggesting that Lqq III is a specific probe for receptor site 3 on cockroach sodium channels. This was confirmed by competitive binding experiments between 125I-Lqq III and scorpion α-Toxins which have less toxicity in insects.
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SCORPION ToxinS AFFECTING SODIUM CURRENT INACTIVATION BIND TO DISTINCT HOMOLOGOUS RECEPTOR SITES ON RAT BRAIN AND INSECT SODIUM CHANNELS
Journal of Biological Chemistry, 1996Co-Authors: Dalia Gordon, Sandrine Cestele, Charles Kopeyan, Marie-france Martin-eauclaire, Edmond Carlier, Rym Ben Khalifa, Marcel Pelhate, Hervé RochatAbstract:Abstract Sodium channels posses receptor sites for many neuroToxins, of which several groups were shown to inhibit sodium current inactivation. Receptor sites that bind α- and α-like scorpion Toxins are of particular interest since neuroToxin binding at these extracellular regions can affect the inactivation process at intramembranal segments of the channel. We examined, for the first time, the interaction of different scorpion neuroToxins, all affecting sodium current inactivation and toxic to mammals, with α-scorpion Toxin receptor sites on both mammalian and insect sodium channels. As specific probes for rat and insect sodium channels, we used the radiolabeled α-scorpion Toxins AaH II and LqhαIT, the most active α-Toxins on mammals and insect, respectively. We demonstrate that the different scorpion Toxins may be classified to several groups, according to their in vivo and in vitro activity on mammalian and insect sodium channels. Analysis of competitive binding interaction reveal that each group may occupy a distinct receptor site on sodium channels. The α-mammal scorpion Toxins and the anti-insect LqhαIT bind to homologous but not identical receptor sites on both rat brain and insect sodium channels. Sea Anemone Toxin ATX II, previously considered to share receptor site 3 with α-scorpion Toxins, is suggested to bind to a partially overlapping receptor site with both AaH II and LqhαIT. Competitive binding interactions with other scorpion Toxins suggest the presence of a putative additional receptor site on sodium channels, which may bind a unique group of these scorpion Toxins (Bom III and IV), active on both mammals and insects. We suggest the presence of a cluster of receptor sites for scorpion Toxins that inhibit sodium current inactivation, which is very similar on insect and rat brain sodium channels, in spite of the structural and pharmacological differences between them. The Sea Anemone Toxin ATX II is also suggested to bind within this cluster.
Michael Gurevitz - One of the best experts on this subject based on the ideXlab platform.
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the specificity of av3 Sea Anemone Toxin for arthropods is determined at linker di ss2 s6 in the pore module of target sodium channels
Biochemical Journal, 2014Co-Authors: Maya Gur Barzilai, Yehu Moran, Roy Kahn, Dalia Gordon, Noa Regev, Michael GurevitzAbstract:Av3 is a peptide neuroToxin from the Sea Anemone Anemonia viridis that shows specificity for arthropod voltage-gated sodium channels (Na v s). Interestingly, Av3 competes with a scorpion α-Toxin on binding to insect Na v s and similarly inhibits the inactivation process, and thus has been classified as ‘receptor site-3 Toxin’, although the two peptides are structurally unrelated. This raises questions as to commonalities and differences in the way both Toxins interact with Na v s. Recently, site-3 was partly resolved for scorpion α-Toxins highlighting S1–S2 and S3–S4 external linkers at the DIV voltage-sensor module and the juxtaposed external linkers at the DI pore module. To uncover channel determinants involved in Av3 specificity for arthropods, the Toxin was examined on channel chimaeras constructed with the external linkers of the mammalian brain Na v 1.2a, which is insensitive to Av3, in the background of the Drosophila DmNa v 1. This approach highlighted the role of linker DI/SS2–S6, adjacent to the channel pore, in determining Av3 specificity. Point mutagenesis at DI/SS2–S6 accompanied by functional assays highlighted Trp 404 and His 405 as a putative point of Av3 interaction with DmNa v 1. His 405 conservation in arthropod Na v s compared with tyrosine in vertebrate Na v s may represent an ancient substitution that explains the contemporary selectivity of Av3. Trp 404 and His 405 localization near the membrane surface and the hydrophobic bioactive surface of Av3 suggest that the Toxin possibly binds at a cleft by DI/S6. A partial overlap in receptor site-3 of both Toxins nearby DI/S6 may explain their binding competition capabilities.
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molecular analysis of the Sea Anemone Toxin av3 reveals selectivity to insects and demonstrates the heterogeneity of receptor site 3 on voltage gated na channels
Biochemical Journal, 2007Co-Authors: Yehu Moran, Lior Cohen, Roy Kahn, Izhar Karbat, Dalia Gordon, Michael GurevitzAbstract:Av3 is a short peptide Toxin from the Sea Anemone Anemonia viridis shown to be active on crustaceans and inactive on mammals. It inhibits inactivation of Navs (voltage-gated Na+ channels) like the structurally dissimilar scorpion α-Toxins and type I Sea Anemone Toxins that bind to receptor site-3. To examine the potency and mode of interaction of Av3 with insect Navs, we established a system for its expression, mutagenized it throughout, and analysed it in toxicity, binding and electrophysiological assays. The recombinant Av3 was found to be highly toxic to blowfly larvae (ED50=2.65±0.46 pmol/100 mg), to compete well with the site-3 Toxin LqhαIT (from the scorpion Leiurus quinquestriatus) on binding to cockroach neuronal membranes (Ki=21.4±7.1 nM), and to inhibit the inactivation of Drosophila melanogaster channel, DmNav1, but not that of mammalian Navs expressed in Xenopus oocytes. Moreover, like other site-3 Toxins, the activity of Av3 was synergically enhanced by ligands of receptor site-4 (e.g. scorpion β-Toxins). The bioactive surface of Av3 was found to consist mainly of aromatic residues and did not resemble any of the bioactive surfaces of other site-3 Toxins. These analyses have portrayed a Toxin that might interact with receptor site-3 in a different fashion compared with other ligands of this site. This assumption was corroborated by a D1701R mutation in DmNav1, which has been shown to abolish the activity of all other site-3 ligands, except Av3. All in all, the present study provides further evidence for the heterogeneity of receptor site-3, and raises Av3 as a unique model for design of selective anti-insect compounds.
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expression and mutagenesis of the Sea Anemone Toxin av2 reveals key amino acid residues important for activity on voltage gated sodium channels
Biochemistry, 2006Co-Authors: Yehu Moran, Lior Cohen, Roy Kahn, Izhar Karbat, Dalia Gordon, Michael GurevitzAbstract:: Type I Sea Anemone Toxins are highly potent modulators of voltage-gated Na-channels (Na(v)s) and compete with the structurally dissimilar scorpion alpha-Toxins on binding to receptor site-3. Although these features provide two structurally different probes for studying receptor site-3 and channel fast inactivation, the bioactive surface of Sea Anemone Toxins has not been fully resolved. We established an efficient expression system for Av2 (known as ATX II), a highly insecticidal Sea Anemone Toxin from Anemonia viridis (previously named A. sulcata), and mutagenized it throughout. Each Toxin mutant was analyzed in toxicity and binding assays as well as by circular dichroism spectroscopy to discern the effects derived from structural perturbation from those related to bioactivity. Six residues were found to constitute the anti-insect bioactive surface of Av2 (Val-2, Leu-5, Asn-16, Leu-18, and Ile-41). Further analysis of nine Av2 mutants on the human heart channel Na(v)1.5 expressed in Xenopus oocytes indicated that the bioactive surfaces toward insects and mammals practically coincide but differ from the bioactive surface of a structurally similar Sea Anemone Toxin, Anthopleurin B, from Anthopleura xanthogrammica. Hence, our results not only demonstrate clear differences in the bioactive surfaces of Av2 and scorpion alpha-Toxins but also indicate that despite the general conservation in structure and importance of the Arg-14 loop and its flanking residues Gly-10 and Gly-20 for function, the surface of interaction between different Sea Anemone Toxins and Na(v)s varies.
Yehu Moran - One of the best experts on this subject based on the ideXlab platform.
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the specificity of av3 Sea Anemone Toxin for arthropods is determined at linker di ss2 s6 in the pore module of target sodium channels
Biochemical Journal, 2014Co-Authors: Maya Gur Barzilai, Yehu Moran, Roy Kahn, Dalia Gordon, Noa Regev, Michael GurevitzAbstract:Av3 is a peptide neuroToxin from the Sea Anemone Anemonia viridis that shows specificity for arthropod voltage-gated sodium channels (Na v s). Interestingly, Av3 competes with a scorpion α-Toxin on binding to insect Na v s and similarly inhibits the inactivation process, and thus has been classified as ‘receptor site-3 Toxin’, although the two peptides are structurally unrelated. This raises questions as to commonalities and differences in the way both Toxins interact with Na v s. Recently, site-3 was partly resolved for scorpion α-Toxins highlighting S1–S2 and S3–S4 external linkers at the DIV voltage-sensor module and the juxtaposed external linkers at the DI pore module. To uncover channel determinants involved in Av3 specificity for arthropods, the Toxin was examined on channel chimaeras constructed with the external linkers of the mammalian brain Na v 1.2a, which is insensitive to Av3, in the background of the Drosophila DmNa v 1. This approach highlighted the role of linker DI/SS2–S6, adjacent to the channel pore, in determining Av3 specificity. Point mutagenesis at DI/SS2–S6 accompanied by functional assays highlighted Trp 404 and His 405 as a putative point of Av3 interaction with DmNa v 1. His 405 conservation in arthropod Na v s compared with tyrosine in vertebrate Na v s may represent an ancient substitution that explains the contemporary selectivity of Av3. Trp 404 and His 405 localization near the membrane surface and the hydrophobic bioactive surface of Av3 suggest that the Toxin possibly binds at a cleft by DI/S6. A partial overlap in receptor site-3 of both Toxins nearby DI/S6 may explain their binding competition capabilities.
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bcstx3 is a founder of a novel Sea Anemone Toxin family of potassium channel blocker
FEBS Journal, 2013Co-Authors: Diego J B Orts, Yehu Moran, Camila Takeno Cologna, Steve Peigneur, Bruno Madio, Daniela Praher, Loic Quinton, Edwin De Pauw, Jose Eduardo P W Bicudo, Jan TytgatAbstract:Sea Anemone venoms have become a rich source of peptide Toxins which are invaluable tools for studying the structure and functions of ion channels. In this work, BcsTx3, a Toxin found in the venom of a Bunodosoma caissarum (population captured at the Saint Peter and Saint Paul Archipelago, Brazil) was purified and biochemically and pharmacologically characterized. The pharmacological effects were studied on 12 different subtypes of voltage-gated potassium channels (KV1.1–KV1.6; KV2.1; KV3.1; KV4.2; KV4.3; hERG and Shaker IR) and three cloned voltage-gated sodium channel isoforms (NaV1.2, NaV1.4 and BgNaV1.1) expressed in Xenopus laevis oocytes. BcsTx3 shows a high affinity for Drosophila Shaker IR channels over rKv1.2, hKv1.3 and rKv1.6, and is not active on NaV channels. Biochemical characterization reveals that BcsTx3 is a 50 amino acid peptide crosslinked by four disulfide bridges, and sequence comparison allowed BcsTx3 to be classified as a novel type of Sea Anemone Toxin acting on KV channels. Moreover, putative Toxins homologous to BcsTx3 from two additional actiniarian species suggest an ancient origin of this newly discovered Toxin family.
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molecular analysis of the Sea Anemone Toxin av3 reveals selectivity to insects and demonstrates the heterogeneity of receptor site 3 on voltage gated na channels
Biochemical Journal, 2007Co-Authors: Yehu Moran, Lior Cohen, Roy Kahn, Izhar Karbat, Dalia Gordon, Michael GurevitzAbstract:Av3 is a short peptide Toxin from the Sea Anemone Anemonia viridis shown to be active on crustaceans and inactive on mammals. It inhibits inactivation of Navs (voltage-gated Na+ channels) like the structurally dissimilar scorpion α-Toxins and type I Sea Anemone Toxins that bind to receptor site-3. To examine the potency and mode of interaction of Av3 with insect Navs, we established a system for its expression, mutagenized it throughout, and analysed it in toxicity, binding and electrophysiological assays. The recombinant Av3 was found to be highly toxic to blowfly larvae (ED50=2.65±0.46 pmol/100 mg), to compete well with the site-3 Toxin LqhαIT (from the scorpion Leiurus quinquestriatus) on binding to cockroach neuronal membranes (Ki=21.4±7.1 nM), and to inhibit the inactivation of Drosophila melanogaster channel, DmNav1, but not that of mammalian Navs expressed in Xenopus oocytes. Moreover, like other site-3 Toxins, the activity of Av3 was synergically enhanced by ligands of receptor site-4 (e.g. scorpion β-Toxins). The bioactive surface of Av3 was found to consist mainly of aromatic residues and did not resemble any of the bioactive surfaces of other site-3 Toxins. These analyses have portrayed a Toxin that might interact with receptor site-3 in a different fashion compared with other ligands of this site. This assumption was corroborated by a D1701R mutation in DmNav1, which has been shown to abolish the activity of all other site-3 ligands, except Av3. All in all, the present study provides further evidence for the heterogeneity of receptor site-3, and raises Av3 as a unique model for design of selective anti-insect compounds.
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expression and mutagenesis of the Sea Anemone Toxin av2 reveals key amino acid residues important for activity on voltage gated sodium channels
Biochemistry, 2006Co-Authors: Yehu Moran, Lior Cohen, Roy Kahn, Izhar Karbat, Dalia Gordon, Michael GurevitzAbstract:: Type I Sea Anemone Toxins are highly potent modulators of voltage-gated Na-channels (Na(v)s) and compete with the structurally dissimilar scorpion alpha-Toxins on binding to receptor site-3. Although these features provide two structurally different probes for studying receptor site-3 and channel fast inactivation, the bioactive surface of Sea Anemone Toxins has not been fully resolved. We established an efficient expression system for Av2 (known as ATX II), a highly insecticidal Sea Anemone Toxin from Anemonia viridis (previously named A. sulcata), and mutagenized it throughout. Each Toxin mutant was analyzed in toxicity and binding assays as well as by circular dichroism spectroscopy to discern the effects derived from structural perturbation from those related to bioactivity. Six residues were found to constitute the anti-insect bioactive surface of Av2 (Val-2, Leu-5, Asn-16, Leu-18, and Ile-41). Further analysis of nine Av2 mutants on the human heart channel Na(v)1.5 expressed in Xenopus oocytes indicated that the bioactive surfaces toward insects and mammals practically coincide but differ from the bioactive surface of a structurally similar Sea Anemone Toxin, Anthopleurin B, from Anthopleura xanthogrammica. Hence, our results not only demonstrate clear differences in the bioactive surfaces of Av2 and scorpion alpha-Toxins but also indicate that despite the general conservation in structure and importance of the Arg-14 loop and its flanking residues Gly-10 and Gly-20 for function, the surface of interaction between different Sea Anemone Toxins and Na(v)s varies.
Stephan Kellenberger - One of the best experts on this subject based on the ideXlab platform.
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inhibition of voltage gated na currents in sensory neurones by the Sea Anemone Toxin apetx2
British Journal of Pharmacology, 2012Co-Authors: Maxime G Blanchard, Lachlan D Rash, Stephan KellenbergerAbstract:BACKGROUND AND PURPOSE: APETx2, a Toxin from the Sea Anemone Anthropleura elegantissima, inhibits acid-sensing ion channel 3 (ASIC3)-containing homo- and heterotrimeric channels with IC(50) values < 100 nM and 0.1-2 microM respectively. ASIC3 channels mediate acute acid-induced and inflammatory pain response and APETx2 has been used as a selective pharmacological tool in animal studies. Toxins from Sea Anemones also modulate voltage-gated Na(+) channel (Na(v) ) function. Here we tested the effects of APETx2 on Na(v) function in sensory neurones. EXPERIMENTAL APPROACH: Effects of APETx2 on Na(v) function were studied in rat dorsal root ganglion (DRG) neurones by whole-cell patch clamp. KEY RESULTS: APETx2 inhibited the tetrodoToxin (TTX)-resistant Na(v) 1.8 currents of DRG neurones (IC(50) , 2.6 microM). TTX-sensitive currents were less inhibited. The inhibition of Na(v) 1.8 currents was due to a rightward shift in the voltage dependence of activation and a reduction of the maximal macroscopic conductance. The inhibition of Na(v) 1.8 currents by APETx2 was confirmed with cloned channels expressed in Xenopus oocytes. In current-clamp experiments in DRG neurones, the number of action potentials induced by injection of a current ramp was reduced by APETx2. CONCLUSIONS AND IMPLICATIONS: APETx2 inhibited Na(v) 1.8 channels, in addition to ASIC3 channels, at concentrations used in in vivo studies. The limited specificity of this Toxin should be taken into account when using APETx2 as a pharmacological tool. Its dual action will be an advantage for the use of APETx2 or its derivatives as analgesic drugs.
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Inhibition of voltage-gated Na(+) currents in sensory neurones by the Sea Anemone Toxin APETx2.
British Journal of Pharmacology, 2012Co-Authors: Maxime G Blanchard, Lachlan D Rash, Stephan KellenbergerAbstract:BACKGROUND AND PURPOSE: APETx2, a Toxin from the Sea Anemone Anthropleura elegantissima, inhibits acid-sensing ion channel 3 (ASIC3)-containing homo- and heterotrimeric channels with IC(50) values < 100 nM and 0.1-2 microM respectively. ASIC3 channels mediate acute acid-induced and inflammatory pain response and APETx2 has been used as a selective pharmacological tool in animal studies. Toxins from Sea Anemones also modulate voltage-gated Na(+) channel (Na(v) ) function. Here we tested the effects of APETx2 on Na(v) function in sensory neurones. EXPERIMENTAL APPROACH: Effects of APETx2 on Na(v) function were studied in rat dorsal root ganglion (DRG) neurones by whole-cell patch clamp. KEY RESULTS: APETx2 inhibited the tetrodoToxin (TTX)-resistant Na(v) 1.8 currents of DRG neurones (IC(50) , 2.6 microM). TTX-sensitive currents were less inhibited. The inhibition of Na(v) 1.8 currents was due to a rightward shift in the voltage dependence of activation and a reduction of the maximal macroscopic conductance. The inhibition of Na(v) 1.8 currents by APETx2 was confirmed with cloned channels expressed in Xenopus oocytes. In current-clamp experiments in DRG neurones, the number of action potentials induced by injection of a current ramp was reduced by APETx2. CONCLUSIONS AND IMPLICATIONS: APETx2 inhibited Na(v) 1.8 channels, in addition to ASIC3 channels, at concentrations used in in vivo studies. The limited specificity of this Toxin should be taken into account when using APETx2 as a pharmacological tool. Its dual action will be an advantage for the use of APETx2 or its derivatives as analgesic drugs.
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inhibition of voltage gated na currents in sensory neurons by the Sea Anemone Toxin apetx2
Biophysical Journal, 2012Co-Authors: Maxime G Blanchard, Lachlan D Rash, Stephan KellenbergerAbstract:ASICs are neuronal H+-gated channel that are transiently opened by extracellular acidification. Functional ASIC channels are made of homotrimeric or heterotrimeric complexes of different ASIC subunits (ASIC1a, −1b, −2a, −2b and 3). APETx2, a Toxin from the Sea Anemone Anthropleura elegantissima inhibits homotrimeric ASIC3 with IC50<100 nM. In rat sensory neurons (DRG), where heterotrimeric channels are expressed, higher concentration are necessary to block ASIC3 containing channels (0.1-2μM). Several animal studies relied on APETx2 as a selective pharmacological tool to study ASIC3 physiological role.A large number of Toxins from Sea Anemone have been previously shown to modulate voltage-gated Na+ channel (Nav) function. The aim of this study was to test whether APETx2, at concentrations used to block heterotrimeric ASIC3 containing channels, affects Nav function in sensory neurons. The effect of APETx2 on Nav function was studied using the whole-cell patch-clamp technique on acutely dissociated small-diameter rat dorsal root ganglion (DRG) neurons.In our study, APETx2 inhibited the tetrodoToxin (TTX)-resistant Nav1.8 currents of DRG neurons in a concentration-dependent manner with an IC50 of ∼3 μM. TTX-sensitive currents were inhibited to a smaller extent. The observed inhibition of Nav1.8 currents is due to a rightward shift in the voltage dependence of activation, and a reduction of the maximal macroscopic conductance. In current-clamp experiments in DRG neurons the number of action potentials induced by injection of a current ramp was reduced by APETx2.APETx2 inhibits, in addition to ASIC3, Nav1.8 channels at concentrations used in in vivo studies. The limited specificity of this Toxin should be taken into account when using APETx2 as a pharmacological tool. Its dual action will be an advantage for the use of APETx2 or its derivatives as analgesic drugs.
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Inhibition of voltage-gated Na+ currents in sensory neurons by the Sea Anemone Toxin APETx2
Biophysical Journal, 2012Co-Authors: Maxime G Blanchard, Lachlan D Rash, Stephan KellenbergerAbstract:ASICs are neuronal H+-gated channel that are transiently opened by extracellular acidification. Functional ASIC channels are made of homotrimeric or heterotrimeric complexes of different ASIC subunits (ASIC1a, −1b, −2a, −2b and 3). APETx2, a Toxin from the Sea Anemone Anthropleura elegantissima inhibits homotrimeric ASIC3 with IC50
Jan Tytgat - One of the best experts on this subject based on the ideXlab platform.
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abetx1 is a novel Sea Anemone Toxin with a dual mechanism of action on shaker type k channels activation
Marine Drugs, 2018Co-Authors: Diego J B Orts, Steve Peigneur, Jose Eduardo P W Bicudo, Laiz Costa Silvagoncalves, Manoel Arcisiomiranda, Jan TytgatAbstract:Voltage-gated potassium (KV) channels regulate diverse physiological processes and are an important target for developing novel therapeutic approaches. Sea Anemone (Cnidaria, Anthozoa) venoms comprise a highly complex mixture of peptide Toxins with diverse and selective pharmacology on KV channels. From the nematocysts of the Sea Anemone Actinia bermudensis, a peptide that we named AbeTx1 was purified and functionally characterized on 12 different subtypes of KV channels (KV1.1–KV1.6; KV2.1; KV3.1; KV4.2; KV4.3; KV11.1; and, Shaker IR), and three voltage-gated sodium channel isoforms (NaV1.2, NaV1.4, and BgNaV). AbeTx1 was selective for Shaker-related K+ channels and is capable of inhibiting K+ currents, not only by blocking the K+ current of KV1.2 subtype, but by altering the energetics of activation of KV1.1 and KV1.6. Moreover, experiments using six synthetic alanine point-mutated analogs further showed that a ring of basic amino acids acts as a multipoint interaction for the binding of the Toxin to the channel. The AbeTx1 primary sequence is composed of 17 amino acids with a high proportion of lysines and arginines, including two disulfide bridges (Cys1–Cys4 and Cys2–Cys3), and it is devoid of aromatic or aliphatic amino acids. Secondary structure analysis reveals that AbeTx1 has a highly flexible, random-coil-like conformation, but with a tendency of structuring in the beta sheet. Its overall structure is similar to open-ended cyclic peptides found on the scorpion κ-KTx Toxins family, cone snail venoms, and antimicrobial peptides.
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apetx4 a novel Sea Anemone Toxin and a modulator of the cancer relevant potassium channel kv10 1
Marine Drugs, 2017Co-Authors: Lien Moreels, Steve Peigneur, Loic Quinton, Edwin De Pauw, Lászlo Béress, Diogo T Galan, Etienne Waelkens, Luis A Pardo, Jan TytgatAbstract:The human ether-a-go-go channel (hEag1 or KV10.1) is a cancer-relevant voltage-gated potassium channel that is overexpressed in a majority of human tumors. Peptides that are able to selectively inhibit this channel can be lead compounds in the Search for new anticancer drugs. Here, we report the activity-guided purification and electrophysiological characterization of a novel KV10.1 inhibitor from the Sea Anemone Anthopleura elegantissima. Purified Sea Anemone fractions were screened for inhibitory activity on KV10.1 by measuring whole-cell currents as expressed in Xenopus laevis oocytes using the two-microelectrode voltage clamp technique. Fractions that showed activity on Kv10.1 were further purified by RP-HPLC. The amino acid sequence of the peptide was determined by a combination of MALDI- LIFT-TOF/TOF MS/MS and CID-ESI-FT-ICR MS/MS and showed a high similarity with APETx1 and APETx3 and was therefore named APETx4. Subsequently, the peptide was electrophysiologically characterized on KV10.1. The selectivity of the Toxin was investigated on an array of voltage-gated ion channels, including the cardiac human ether-a-go-go-related gene potassium channel (hERG or Kv11.1). The Toxin inhibits KV10.1 with an IC50 value of 1.1 μM. In the presence of a similar Toxin concentration, a shift of the activation curve towards more positive potentials was observed. Similar to the effect of the gating modifier Toxin APETx1 on hERG, the inhibition of Kv10.1 by the isolated Toxin is reduced at more positive voltages and the peptide seems to keep the channel in a closed state. Although the peptide also induces inhibitory effects on other KV and NaV channels, it exhibits no significant effect on hERG. Moreover, APETx4 induces a concentration-dependent cytotoxic and proapoptotic effect in various cancerous and noncancerous cell lines. This newly identified KV10.1 inhibitor can be used as a tool to further characterize the oncogenic channel KV10.1 or as a scaffold for the design and synthesis of more potent and safer anticancer drugs.
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bcstx3 is a founder of a novel Sea Anemone Toxin family of potassium channel blocker
FEBS Journal, 2013Co-Authors: Diego J B Orts, Yehu Moran, Camila Takeno Cologna, Steve Peigneur, Bruno Madio, Daniela Praher, Loic Quinton, Edwin De Pauw, Jose Eduardo P W Bicudo, Jan TytgatAbstract:Sea Anemone venoms have become a rich source of peptide Toxins which are invaluable tools for studying the structure and functions of ion channels. In this work, BcsTx3, a Toxin found in the venom of a Bunodosoma caissarum (population captured at the Saint Peter and Saint Paul Archipelago, Brazil) was purified and biochemically and pharmacologically characterized. The pharmacological effects were studied on 12 different subtypes of voltage-gated potassium channels (KV1.1–KV1.6; KV2.1; KV3.1; KV4.2; KV4.3; hERG and Shaker IR) and three cloned voltage-gated sodium channel isoforms (NaV1.2, NaV1.4 and BgNaV1.1) expressed in Xenopus laevis oocytes. BcsTx3 shows a high affinity for Drosophila Shaker IR channels over rKv1.2, hKv1.3 and rKv1.6, and is not active on NaV channels. Biochemical characterization reveals that BcsTx3 is a 50 amino acid peptide crosslinked by four disulfide bridges, and sequence comparison allowed BcsTx3 to be classified as a novel type of Sea Anemone Toxin acting on KV channels. Moreover, putative Toxins homologous to BcsTx3 from two additional actiniarian species suggest an ancient origin of this newly discovered Toxin family.
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trpv1 channel as new target for marine Toxins example of giganToxin i a Sea Anemone Toxin acting via modulation of the pla2 pathway
Acta Chimica Slovenica, 2011Co-Authors: Eva Cuypers, Steve Peigneur, Sarah Debaveye, Kazuo Shiomi, Jan TytgatAbstract:: GiganToxin I, isolated from Sea Anemone Stichodactyla gigantea, was previously described as the first epidermal growth factor (EGF)-like Toxin from natural origin. In this study, we discovered the interaction between the transient receptor potential vanilloid subtype I (TRPV1) channels and giganToxin I. The TRPV1 channel is a non-selective cation channel involved in pain sensation and is described as pharmacological target of cnidaria venom. Our results highlight the involvement of the epidermal growth factor receptor/phospholipaSea2/arachidonic acid/lipoxygenase (EGFR/PLA2/AA/ LOX) pathway in the indirect activation of TRPV1 channels by giganToxin I. This is the first time that this pathway is described in the indirect activation of TRPV1 channels by Toxins. This knowledge not only gives insights into the possible induced effects by this new group of Toxins, but also leads to a better understanding of the regulatory mechanism of TRPV1 channels themselves.