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Novel Therapeutic Approaches of Ion Channels and Transporters in Cancer. Rev Physiol Biochem Pharmacol 2020; 183:45-101. [PMID: 32715321 DOI: 10.1007/112_2020_28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The expression and function of many ion channels and transporters in cancer cells display major differences in comparison to those from healthy cells. These differences provide the cancer cells with advantages for tumor development. Accordingly, targeting ion channels and transporters have beneficial anticancer effects including inhibition of cancer cell proliferation, migration, invasion, metastasis, tumor vascularization, and chemotherapy resistance, as well as promoting apoptosis. Some of the molecular mechanisms associating ion channels and transporters with cancer include the participation of oxidative stress, immune response, metabolic pathways, drug synergism, as well as noncanonical functions of ion channels. This diversity of mechanisms offers an exciting possibility to suggest novel and more effective therapeutic approaches to fight cancer. Here, we review and discuss most of the current knowledge suggesting novel therapeutic approaches for cancer therapy targeting ion channels and transporters. The role and regulation of ion channels and transporters in cancer provide a plethora of exceptional opportunities in drug design, as well as novel and promising therapeutic approaches that may be used for the benefit of cancer patients.
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Housley DM, Pinyon JL, von Jonquieres G, Perera CJ, Smout M, Liddell MJ, Jennings EA, Wilson D, Housley GD. Australian Scorpion Hormurus waigiensis Venom Fractions Show Broad Bioactivity Through Modulation of Bio-Impedance and Cytosolic Calcium. Biomolecules 2020; 10:E617. [PMID: 32316246 PMCID: PMC7226344 DOI: 10.3390/biom10040617] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/06/2020] [Accepted: 04/06/2020] [Indexed: 12/13/2022] Open
Abstract
Scorpion venoms are a rich source of bioactive molecules, but characterisation of toxin peptides affecting cytosolic Ca2+, central to cell signalling and cell death, is limited. We undertook a functional screening of the venom of the Australian scorpion Hormurus waigiensis to determine the breadth of Ca2+ mobilisation. A human embryonic kidney (HEK293) cell line stably expressing the genetically encoded Ca2+ reporter GCaMP5G and the rabbit type 1 ryanodine receptor (RyR1) was developed as a biosensor. Size-exclusion Fast Protein Liquid Chromatography separated the venom into 53 fractions, constituting 12 chromatographic peaks. Liquid chromatography mass spectroscopy identified 182 distinct molecules with 3 to 63 components per peak. The molecular weights varied from 258 Da-13.6 kDa, with 53% under 1 kDa. The majority of the venom chromatographic peaks (tested as six venom pools) were found to reversibly modulate cell monolayer bioimpedance, detected using the xCELLigence platform (ACEA Biosciences). Confocal Ca2+ imaging showed 9/14 peak samples, with molecules spanning the molecular size range, increased cytosolic Ca2+ mobilization. H. waigiensis venom Ca2+ activity was correlated with changes in bio-impedance, reflecting multi-modal toxin actions on cell physiology across the venom proteome.
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Affiliation(s)
- David M. Housley
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; (D.M.H.); (J.L.P.); (G.v.J.); (C.J.P.)
- Department of Otolaryngology, Sunshine Coast University Hospital, Sunshine Coast, QLD 4575, Australia
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, QLD 4878, Australia;
| | - Jeremy L. Pinyon
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; (D.M.H.); (J.L.P.); (G.v.J.); (C.J.P.)
| | - Georg von Jonquieres
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; (D.M.H.); (J.L.P.); (G.v.J.); (C.J.P.)
| | - Chamini J. Perera
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; (D.M.H.); (J.L.P.); (G.v.J.); (C.J.P.)
| | - Michael Smout
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD 4878, Australia; (M.S.); (D.W.)
- Centre for Molecular Therapeutics, James Cook University, Cairns, QLD 4878, Australia
| | - Michael J. Liddell
- Centre for Tropical Environmental and Sustainability Science, College of Science & Engineering, Cairns Campus, James Cook University, Cairns, QLD 4878, Australia;
| | - Ernest A. Jennings
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, QLD 4878, Australia;
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD 4878, Australia; (M.S.); (D.W.)
- Centre for Molecular Therapeutics, James Cook University, Cairns, QLD 4878, Australia
| | - David Wilson
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD 4878, Australia; (M.S.); (D.W.)
- Centre for Molecular Therapeutics, James Cook University, Cairns, QLD 4878, Australia
| | - Gary D. Housley
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; (D.M.H.); (J.L.P.); (G.v.J.); (C.J.P.)
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Barros F, de la Peña P, Domínguez P, Sierra LM, Pardo LA. The EAG Voltage-Dependent K + Channel Subfamily: Similarities and Differences in Structural Organization and Gating. Front Pharmacol 2020; 11:411. [PMID: 32351384 PMCID: PMC7174612 DOI: 10.3389/fphar.2020.00411] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/18/2020] [Indexed: 12/17/2022] Open
Abstract
EAG (ether-à-go-go or KCNH) are a subfamily of the voltage-gated potassium (Kv) channels. Like for all potassium channels, opening of EAG channels drives the membrane potential toward its equilibrium value for potassium, thus setting the resting potential and repolarizing action potentials. As voltage-dependent channels, they switch between open and closed conformations (gating) when changes in membrane potential are sensed by a voltage sensing domain (VSD) which is functionally coupled to a pore domain (PD) containing the permeation pathway, the potassium selectivity filter, and the channel gate. All Kv channels are tetrameric, with four VSDs formed by the S1-S4 transmembrane segments of each subunit, surrounding a central PD with the four S5-S6 sections arranged in a square-shaped structure. Structural information, mutagenesis, and functional experiments, indicated that in "classical/Shaker-type" Kv channels voltage-triggered VSD reorganizations are transmitted to PD gating via the α-helical S4-S5 sequence that links both modules. Importantly, these Shaker-type channels share a domain-swapped VSD/PD organization, with each VSD contacting the PD of the adjacent subunit. In this case, the S4-S5 linker, acting as a rigid mechanical lever (electromechanical lever coupling), would lead to channel gate opening at the cytoplasmic S6 helices bundle. However, new functional data with EAG channels split between the VSD and PD modules indicate that, in some Kv channels, alternative VSD/PD coupling mechanisms do exist. Noticeably, recent elucidation of the architecture of some EAG channels, and other relatives, showed that their VSDs are non-domain swapped. Despite similarities in primary sequence and predicted structural organization for all EAG channels, they show marked kinetic differences whose molecular basis is not completely understood. Thus, while a common general architecture may establish the gating system used by the EAG channels and the physicochemical coupling of voltage sensing to gating, subtle changes in that common structure, and/or allosteric influences of protein domains relatively distant from the central gating machinery, can crucially influence the gating process. We consider here the latest advances on these issues provided by the elucidation of eag1 and erg1 three-dimensional structures, and by both classical and more recent functional studies with different members of the EAG subfamily.
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Affiliation(s)
- Francisco Barros
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, Oviedo, Spain
| | - Pilar de la Peña
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, Oviedo, Spain
| | - Pedro Domínguez
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, Oviedo, Spain
| | - Luisa Maria Sierra
- Departamento de Biología Funcional (Area de Genética), Instituto Universitario de Oncología del Principado de Asturias (IUOPA), Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Universidad de Oviedo, Oviedo, Spain
| | - Luis A. Pardo
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany
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Nematocyst types and venom effects of Aurelia aurita and Velella velella from the Mediterranean Sea. Toxicon 2020; 175:57-63. [DOI: 10.1016/j.toxicon.2019.12.155] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 12/06/2019] [Accepted: 12/21/2019] [Indexed: 01/10/2023]
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Relative positioning of Kv11.1 (hERG) K + channel cytoplasmic domain-located fluorescent tags toward the plasma membrane. Sci Rep 2018; 8:15494. [PMID: 30341381 PMCID: PMC6195548 DOI: 10.1038/s41598-018-33492-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/01/2018] [Indexed: 12/17/2022] Open
Abstract
Recent cryo-EM data have provided a view of the KCNH potassium channels molecular structures. However, some details about the cytoplasmic domains organization and specially their rearrangements associated to channel functionality are still lacking. Here we used the voltage-dependent dipicrylamine (DPA)-induced quench of fluorescent proteins (FPS) linked to different positions at the cytoplasmic domains of KCNH2 (hERG) to gain some insights about the coarse structure of these channel parts. Fast voltage-clamp fluorometry with HEK293 cells expressing membrane-anchored FPs under conditions in which only the plasma membrane potential is modified, demonstrated DPA voltage-dependent translocation and subsequent FRET-triggered FP quenching. Our data demonstrate for the first time that the distance between an amino-terminal FP tag and the intracellular plasma membrane surface is shorter than that between the membrane and a C-terminally-located tag. The distances varied when the FPs were attached to other positions along the channel cytoplasmic domains. In some cases, we also detected slower fluorometric responses following the fast voltage-dependent dye translocation, indicating subsequent label movements orthogonal to the plasma membrane. This finding suggests the existence of additional conformational rearrangements in the hERG cytoplasmic domains, although their association with specific aspects of channel operation remains to be established.
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Housley DM, Housley GD, Liddell MJ, Jennings EA. Scorpion toxin peptide action at the ion channel subunit level. Neuropharmacology 2016; 127:46-78. [PMID: 27729239 DOI: 10.1016/j.neuropharm.2016.10.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 09/06/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022]
Abstract
This review categorizes functionally validated actions of defined scorpion toxin (SCTX) neuropeptides across ion channel subclasses, highlighting key trends in this rapidly evolving field. Scorpion envenomation is a common event in many tropical and subtropical countries, with neuropharmacological actions, particularly autonomic nervous system modulation, causing significant mortality. The primary active agents within scorpion venoms are a diverse group of small neuropeptides that elicit specific potent actions across a wide range of ion channel classes. The identification and functional characterisation of these SCTX peptides has tremendous potential for development of novel pharmaceuticals that advance knowledge of ion channels and establish lead compounds for treatment of excitable tissue disorders. This review delineates the unique specificities of 320 individual SCTX peptides that collectively act on 41 ion channel subclasses. Thus the SCTX research field has significant translational implications for pathophysiology spanning neurotransmission, neurohumoral signalling, sensori-motor systems and excitation-contraction coupling. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- David M Housley
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia; Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Gary D Housley
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia
| | - Michael J Liddell
- Centre for Tropical Environmental and Sustainability Science and College of Science & Engineering, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia
| | - Ernest A Jennings
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia; Centre for Biodiscovery and Molecular Development of Therapeutics, James Cook University, Queensland 4878, Australia; Australian Institute of Tropical Health and Medicine, James Cook University, Cairns Campus, QLD, Australia
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Arrhythmogenic effect of a crude extract from sea anemone Condylactis gigantea: possible involvement of rErg1 channels. Toxicon 2013; 67:47-54. [PMID: 23499927 DOI: 10.1016/j.toxicon.2013.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/11/2013] [Accepted: 02/22/2013] [Indexed: 11/21/2022]
Abstract
Sea anemones possess a number of peptide toxins that target ion channels which provide powerful tools to study the molecular basis of diverse signaling pathways. It is also acknowledged that currents through Erg1 K(+) channels in cardiac myocytes are important for electrical stability of the heart and alterations in its activity has been linked to the onset of a potentially life-threatening heart condition named long QT syndrome type 2. Here, we report that a crude extract from sea anemone Condylactis gigantea significantly increases the QT interval and has arrhythmogenic effects in the rat heart. Furthermore, a bioassay-guided purification procedure allowed the isolation of a chromatographic fraction containing a major component with a molecular mass of 4478 Da from the crude extract, which causes a significant inhibition of whole-cell patch-clamp currents through recombinant Erg1 channels, responsible of the rapid delayed rectifying current crucial for electrical activity in the heart. Further studies could provide relevant information on the molecular mechanism of C. gigantea peptide toxins which represent promising tools in studying the physiology of diverse ion channels.
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Cell type influences the molecular mechanisms involved in hormonal regulation of ERG K+ channels. Pflugers Arch 2012; 463:685-702. [PMID: 22415214 DOI: 10.1007/s00424-012-1094-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 02/25/2012] [Indexed: 10/28/2022]
Abstract
While the thyrotropin-releasing hormone (TRH) effect of raising intracellular Ca(2+) levels has been shown to rely on G(q/11) and PLC activation, the molecular mechanisms involved in the regulation of ERG K(+) channels by TRH are still partially unknown. We have analysed the effects of βγ scavengers, Akt/PKB inactivation, and TRH receptor (TRH-R) overexpression on such regulation in native and heterologous expression cell systems. In native rat pituitary GH(3) cells β-ARK/CT, Gα(t), and phosducin significantly reduced TRH inhibition of rERG currents, whereas in HEK-H36/T1 cells permanently expressing TRH-R and hERG, neither of the βγ scavengers affected the TRH-induced shift in V (1/2). Use of specific siRNAs to knock Akt/PKB expression down abolished the TRH effect on HEK-H36/T1 cell hERG, but not on rERG from GH(3) cells. Indeed, wortmannin or long insulin pretreatment also blocked TRH regulation of ERG currents in HEK-H36/T1 but not in GH(3) cells. To determine whether these differences could be related to the amount of TRH-Rs in the cell, we studied the TRH concentration dependence of the Ca(2+) and ERG responses in GH(3) cells overexpressing the receptors. The data indicated that independent of the receptor number additional cellular factor(s) contribute differently to couple the TRH-R to hERG channel modulation in HEK-H36/T1 cells. We conclude that regulation of ERG currents by TRH and its receptor is transduced in GH(3) and HEK-H36/T1 cell systems through common and different elements, and hence that the cell type influences the signalling pathways involved in the TRH-evoked responses.
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Fernández-Trillo J, Barros F, Machín A, Carretero L, Domínguez P, de la Peña P. Molecular determinants of interactions between the N-terminal domain and the transmembrane core that modulate hERG K+ channel gating. PLoS One 2011; 6:e24674. [PMID: 21935437 PMCID: PMC3174182 DOI: 10.1371/journal.pone.0024674] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 08/15/2011] [Indexed: 12/18/2022] Open
Abstract
A conserved eag domain in the cytoplasmic amino terminus of the human ether-a-go-go-related gene (hERG) potassium channel is critical for its slow deactivation gating. Introduction of gene fragments encoding the eag domain are able to restore normal deactivation properties of channels from which most of the amino terminus has been deleted, and also those lacking exclusively the eag domain or carrying a single point mutation in the initial residues of the N-terminus. Deactivation slowing in the presence of the recombinant domain is not observed with channels carrying a specific Y542C point mutation in the S4–S5 linker. On the other hand, mutations in some initial positions of the recombinant fragment also impair its ability to restore normal deactivation. Fluorescence resonance energy transfer (FRET) analysis of fluorophore-tagged proteins under total internal reflection fluorescence (TIRF) conditions revealed a substantial level of FRET between the introduced N-terminal eag fragments and the eag domain-deleted channels expressed at the membrane, but not between the recombinant eag domain and full-length channels with an intact amino terminus. The FRET signals were also minimized when the recombinant eag fragments carried single point mutations in the initial portion of their amino end, and when Y542C mutated channels were used. These data suggest that the restoration of normal deactivation gating by the N-terminal recombinant eag fragment is an intrinsic effect of this domain directed by the interaction of its N-terminal segment with the gating machinery, likely at the level of the S4–S5 linker.
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Affiliation(s)
| | - Francisco Barros
- Department of Biochemistry and Molecular Biology, University of Oviedo, Oviedo, Spain
- * E-mail: (FB); (PdlP)
| | - Angeles Machín
- Department of Biochemistry and Molecular Biology, University of Oviedo, Oviedo, Spain
| | - Luis Carretero
- Department of Biochemistry and Molecular Biology, University of Oviedo, Oviedo, Spain
| | - Pedro Domínguez
- Department of Biochemistry and Molecular Biology, University of Oviedo, Oviedo, Spain
| | - Pilar de la Peña
- Department of Biochemistry and Molecular Biology, University of Oviedo, Oviedo, Spain
- * E-mail: (FB); (PdlP)
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Role of ERG1 isoforms in modulation of ERG1 channel trafficking and function. Pflugers Arch 2010; 460:803-12. [DOI: 10.1007/s00424-010-0855-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 06/13/2010] [Accepted: 06/14/2010] [Indexed: 01/31/2023]
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11
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Arcangeli A, Becchetti A. New Trends in Cancer Therapy: Targeting Ion Channels and Transporters. Pharmaceuticals (Basel) 2010; 3:1202-1224. [PMID: 27713296 PMCID: PMC4034029 DOI: 10.3390/ph3041202] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 03/25/2010] [Accepted: 03/29/2010] [Indexed: 02/07/2023] Open
Abstract
The expression and activity of different channel types mark and regulate specific stages of cancer establishment and progression. Blocking channel activity impairs the growth of some tumors, both in vitro and in vivo, which opens a new field for pharmaceutical research. However, ion channel blockers may produce serious side effects, such as cardiac arrhythmias. For instance, Kv11.1 (hERG1) channels are aberrantly expressed in several human cancers, in which they control different aspects of the neoplastic cell behaviour. hERG1 blockers tend to inhibit cancer growth. However they also retard the cardiac repolarization, thus lengthening the electrocardiographic QT interval, which can lead to life-threatening ventricular arrhythmias. Several possibilities exist to produce less harmful compounds, such as developing specific drugs that bind hERG1 channels in the open state or disassemble the ion channel/integrin complex which appears to be crucial in certain stages of neoplastic progression. The potential approaches to improve the efficacy and safety of ion channel targeting in oncology include: (1) targeting specific conformational channel states; (2) finding ever more specific inhibitors, including peptide toxins, for channel subtypes mainly expressed in well-identified tumors; (3) using specific ligands to convey traceable or cytotoxic compounds; (4) developing channel blocking antibodies; (5) designing new molecular tools to decrease channel expression in selected cancer types. Similar concepts apply to ion transporters such as the Na⁺/K⁺ pump and the Na⁺/H⁺ exchanger. Pharmacological targeting of these transporters is also currently being considered in anti-neoplastic therapy.
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Affiliation(s)
- Annarosa Arcangeli
- Department of Experimental Pathology and Oncology, University of Florence, Italy.
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Italy.
| | - Andrea Becchetti
- Department of Experimental Pathology and Oncology, University of Florence, Italy
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Italy
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Abstract
Several noncardiovascular drugs have the potential to induce Torsades de Pointes cardiac arrhythmias via blockade of the rapid component of the cardiac delayed rectifier K(+) current (I(Kr)), which is encoded by human ether-à-go-go-related gene (hERG). The aim of the present study was to characterize possible interactions between terfenadine, binding to a site located inside the central cavity, and the following substances with various binding sites: dofetilide, fluvoxamine, chlorobutanol, and a hERG-specific toxin isolated from scorpion venom (CnErg1). The whole-cell configuration of the patch-clamp technique was employed on hERG channels stably expressed in human embryonic kidney 293 cells. Terfenadine does not interact with dofetilide or fluvoxamine at hERG channels. Slight subadditive inhibitory effects on hERG peak tail currents were observed when terfenadine and CnErg1 were administered in combination. Terfenadine and chlorobutanol synergistically inhibit hERG peak tail currents and enhance each other's inhibitory effect in a concentration-dependent way. In conclusion, terfenadine interacts with CnErg1 and chlorobutanol, but not with dofetilide or fluvoxamine, at hERG channels. It is shown that interactions between chlorobutanol and a hERG channel blocker binding inside the central cavity (terfenadine) produce synergistic effects on hERG currents.
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Affiliation(s)
- Anne Friemel
- Federal Institute for Drugs and Medical Devices, D-53175 Bonn, Germany
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Raschi E, Ceccarini L, De Ponti F, Recanatini M. hERG-related drug toxicity and models for predicting hERG liability and QT prolongation. Expert Opin Drug Metab Toxicol 2009; 5:1005-21. [PMID: 19572824 DOI: 10.1517/17425250903055070] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND hERG K(+) channels have been recognized as a primary antitarget in safety pharmacology. Their blockade, caused by several drugs with different therapeutic indications, may lead to QT prolongation and, eventually, to potentially fatal arrhythmia, namely torsade de pointes. Therefore, a number of preclinical models have been developed to predict hERG liability early in the drug development process. OBJECTIVE The aim of this review is to outline the present state of the art on drug-induced hERG blockade, providing insights on the predictive value of in vitro and in silico models for hERG liability. METHODS On the basis of latest reports, high-throughput preclinical models have been discussed outlining advantages and limitations. CONCLUSION Although no single model has an absolute value, an integrated risk assessment is recommended to predict the pro-arrhythmic risk of a given drug. This prediction requires expertise from different areas and should encompass emerging issues such as interference with hERG trafficking and QT shortening.
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Affiliation(s)
- Emanuel Raschi
- University of Bologna, Department of Pharmacology, Italy
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Redaelli E, Cassulini RR, Silva DF, Clement H, Schiavon E, Zamudio FZ, Odell G, Arcangeli A, Clare JJ, Alagón A, de la Vega RCR, Possani LD, Wanke E. Target promiscuity and heterogeneous effects of tarantula venom peptides affecting Na+ and K+ ion channels. J Biol Chem 2009; 285:4130-4142. [PMID: 19955179 DOI: 10.1074/jbc.m109.054718] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Venom-derived peptide modulators of ion channel gating are regarded as essential tools for understanding the molecular motions that occur during the opening and closing of ion channels. In this study, we present the characterization of five spider toxins on 12 human voltage-gated ion channels, following observations about the target promiscuity of some spider toxins and the ongoing revision of their "canonical" gating-modifying mode of action. The peptides were purified de novo from the venom of Grammostola rosea tarantulas, and their sequences were confirmed by Edman degradation and mass spectrometry analysis. Their effects on seven tetrodotoxin-sensitive Na(+) channels, the three human ether-à-go-go (hERG)-related K(+) channels, and two human Shaker-related K(+) channels were extensively characterized by electrophysiological techniques. All the peptides inhibited ion conduction through all the Na(+) channels tested, although with distinctive patterns. The peptides also affected the three pharmaceutically relevant hERG isoforms differently. At higher concentrations, all peptides also modified the gating of the Na(+) channels by shifting the activation to more positive potentials, whereas more complex effects were recorded on hERG channels. No effects were evident on the two Shaker-related K(+) channels at concentrations well above the IC(50) value for the affected channels. Given the sequence diversity of the tested peptides, we propose that tarantula toxins should be considered both as multimode and target-promiscuous ion channel modulators; both features should not be ignored when extracting mechanistic interpretations about ion channel gating. Our observations could also aid in future structure-function studies and might help the development of novel ion channel-specific drugs.
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Affiliation(s)
- Elisa Redaelli
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy
| | - Rita Restano Cassulini
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy; the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Deyanira Fuentes Silva
- the Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, Coyoacán DF 04510, México
| | - Herlinda Clement
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Emanuele Schiavon
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy
| | - Fernando Z Zamudio
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - George Odell
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Annarosa Arcangeli
- the Dipartimento di Patologia e Oncologia Sperimentali, Università di Firenze, Viale Morgagni 50, 50134 Firenze, Italy
| | - Jeffrey J Clare
- Gene Expression and Protein Biochemistry, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts SG1 2NY, United Kingdom, and
| | - Alejandro Alagón
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Ricardo C Rodríguez de la Vega
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México; the Structural and Computational Biology/Genome Biology Units, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Lourival D Possani
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Enzo Wanke
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy.
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15
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Sher D, Zlotkin E. A hydra with many heads: Protein and polypeptide toxins from hydra and their biological roles. Toxicon 2009; 54:1148-61. [DOI: 10.1016/j.toxicon.2009.02.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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16
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Castañeda O, Harvey AL. Discovery and characterization of cnidarian peptide toxins that affect neuronal potassium ion channels. Toxicon 2009; 54:1119-24. [DOI: 10.1016/j.toxicon.2009.02.032] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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17
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Wanke E, Zaharenko AJ, Redaelli E, Schiavon E. Actions of sea anemone type 1 neurotoxins on voltage-gated sodium channel isoforms. Toxicon 2009; 54:1102-11. [DOI: 10.1016/j.toxicon.2009.04.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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18
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19
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Abstract
Cnidarians (Coelenterates), a very old and diverse animal phylum, possess a wide variety of biologically active substances that can be considered as toxins. Anthozoan toxins can be classified into two chemically very different groups, namely polypeptide toxins isolated from sea anemones and diterpenes isolated from octocorals. Cubozoan and scyphozoan protein toxins have been the most elusive cnidarian toxins to investigate - despite a tremendous effort in the past few decades, very few of these large, relatively unstable protein toxins were isolated, but recently this has been achieved for cubozoan venoms. Hydrozoans mainly contain large proteins with physiological mechanisms of action similar to the sea anemone and jellyfish pore-forming toxins. This article will focus on the in vivo physiological effects of cnidarian toxins and venoms; their actions at the cellular level will only be considered to understand their actions at the organ and whole animal levels. An understanding of mechanisms underlying the in vivo toxic effects will facilitate the development of more effective treatments of cnidarian envenomations.
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Affiliation(s)
- Dusan Suput
- University of Ljubljana, Faculty of Medicine, Vrazov trg 2, 1104 Ljubljana, Slovenia.
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20
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Diochot S, Lazdunski M. Sea anemone toxins affecting potassium channels. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2009; 46:99-122. [PMID: 19184586 DOI: 10.1007/978-3-540-87895-7_4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The great diversity of K(+) channels and their wide distribution in many tissues are associated with important functions in cardiac and neuronal excitability that are now better understood thanks to the discovery of animal toxins. During the past few decades, sea anemones have provided a variety of toxins acting on voltage-sensitive sodium and, more recently, potassium channels. Currently there are three major structural groups of sea anemone K(+) channel (SAK) toxins that have been characterized. Radioligand binding and electrophysiological experiments revealed that each group contains peptides displaying selective activities for different subfamilies of K(+) channels. Short (35-37 amino acids) peptides in the group I display pore blocking effects on Kv1 channels. Molecular interactions of SAK-I toxins, important for activity and binding on Kv1 channels, implicate a spot of three conserved amino acid residues (Ser, Lys, Tyr) surrounded by other less conserved residues. Long (58-59 amino acids) SAK-II peptides display both enzymatic and K(+) channel inhibitory activities. Medium size (42-43 amino acid) SAK-III peptides are gating modifiers which interact either with cardiac HERG or Kv3 channels by altering their voltage-dependent properties. SAK-III toxins bind to the S3C region in the outer vestibule of Kv channels. Sea anemones have proven to be a rich source of pharmacological tools, and some of the SAK toxins are now useful drugs for the diagnosis and treatment of autoimmune diseases.
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Affiliation(s)
- Sylvie Diochot
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifi que, Université de Nice-Sophia-Antipolis, 660 Route des Lucioles, Valbonne, 06560, France
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21
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Miranda P, Manso DG, Barros F, Carretero L, Hughes TE, Alonso-Ron C, Domínguez P, de la Peña P. FRET with multiply labeled HERG K(+) channels as a reporter of the in vivo coarse architecture of the cytoplasmic domains. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1681-99. [PMID: 18634834 DOI: 10.1016/j.bbamcr.2008.06.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Revised: 05/30/2008] [Accepted: 06/02/2008] [Indexed: 01/16/2023]
Abstract
The intracellular N-terminus of human ether-a-go-go-related gene (HERG) potassium channels constitutes a key determinant of activation and deactivation characteristics and is necessary for hormone-induced modifications of gating properties. However, the general organization of the long amino and carboxy HERG terminals remains unknown. In this study we performed fluorescence resonance energy transfer (FRET) microscopy with a library of fluorescent HERG fusion proteins obtained combining site-directed and transposon-based random insertion of GFP variants into multiple sites of HERG. Determinations of FRET efficiencies with functional HERG channels labeled in different combinations localize the fluorophores, introduced in the amino and carboxy ends, in two quadratic planes of 7.8 and 8.6 nm lateral size, showing a vertical separation of nearly 8 nm without major angular torsion between the planes. Similar analysis using labels at positions 345 and 905 of the amino and carboxy terminals, located them slightly above the planes delimited by the amino and carboxy end labels, respectively. Our data also indicate an almost vertical arrangement of the fluorophores introduced in the NH(2) and COOH ends and at position 905, but a near 45 degrees angular rotation between the planes delimited by these labels and the 345-located fluorophores. Systematic triangulation using interfluorophore distances coming from multiply labeled channels provides an initial constraint on the overall in vivo arrangement of the HERG cytoplasmic domains, suggesting that the C-linker/CNBD region of HERG hangs centrally below the transmembrane core, with the initial portion of the amino terminus around its top and side surfaces directed towards the gating machinery.
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Affiliation(s)
- Pablo Miranda
- Departamento de Bioquímica y Biología Molecular, Edificio Santiago Gascón, Campus del Cristo, Universidad de Oviedo. E-33006. Oviedo, Asturias, Spain
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22
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Two novel ergtoxins, blockers of K+-channels, purified from the Mexican scorpion Centruroides elegans elegans. Neurochem Res 2008; 33:1525-33. [PMID: 18338253 DOI: 10.1007/s11064-008-9634-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Accepted: 02/19/2008] [Indexed: 10/22/2022]
Abstract
Voltage-gated potassium channels of the ether-a-go-go related gene (ERG) family are implicated in many important cellular processes. Three such genes have been cloned (erg1, erg2 and erg3) and shown to be expressed in the central nervous system (CNS) of mammalians. This communication describes the isolation and characterization of two isoforms of scorpion toxin (CeErg4 and CeErg5, systematic nomenclature gamma-KTx1.7 and gamma-KTx1.8, respectively) that can discriminate the various subtypes of ERG channels of human and rat. These peptides were purified from the venom of the Mexican scorpion Centruroides elegans elegans. They contain 42 amino acid residues, tightly folded by four disulfide bridges. Both peptides block in a reversible manner human and rat ERG1 channels, but have no effect on human ERG2. They also block completely and irreversibly the rat ERG2 and the human ERG3 channels hence are excellent tools for the discrimination of the various sub-types of ion-channels studied.
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23
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Raschi E, Vasina V, Poluzzi E, De Ponti F. The hERG K+ channel: target and antitarget strategies in drug development. Pharmacol Res 2008; 57:181-95. [PMID: 18329284 DOI: 10.1016/j.phrs.2008.01.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 01/21/2008] [Accepted: 01/22/2008] [Indexed: 12/16/2022]
Abstract
The human ether-à-go-go related gene (hERG) K+ channel is of great interest for both basic researchers and clinicians because its blockade by drugs can lead to QT prolongation, which is a risk factor for torsades de pointes, a potentially life-threatening arrhythmia. A growing list of agents with "QT liability" have been withdrawn from the market or restricted in their use, whereas others did not even receive regulatory approval for this reason. Thus, hERG K+ channels have become a primary antitarget (i.e. an unwanted target) in drug development because their blockade causes potentially serious side effects. On the other hand, the recent identification and functional characterization of hERG K+ channels not only in the heart, but also in several other tissues (e.g. neurons, smooth muscle and cancer cells) may have far reaching implications for drug development for a possible exploitation of hERG as a target, especially in oncology and cardiology.
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Affiliation(s)
- Emanuel Raschi
- Department of Pharmacology, University of Bologna, Via Irnerio, 48, I-40126 Bologna BO, Bologna, Italy
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24
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Matsushita N, Miyashita M, Sakai A, Nakagawa Y, Miyagawa H. Purification and characterization of a novel short-chain insecticidal toxin with two disulfide bridges from the venom of the scorpion Liocheles australasiae. Toxicon 2007; 50:861-7. [PMID: 17681581 DOI: 10.1016/j.toxicon.2007.06.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 06/20/2007] [Accepted: 06/21/2007] [Indexed: 10/23/2022]
Abstract
Scorpion venoms contain a variety of peptides toxic to mammals, insects and crustaceans. Most of the scorpion toxins have been isolated from the venoms of scorpions in the family Buthidae, but little interest has been paid to non-Buthidae scorpions. In this study, we isolated a short-chain insecticidal toxin (LaIT1) from the venom of the scorpion Liocheles australasiae belonging to the Hemiscorpiidae family. This toxin showed insect toxicity against crickets at a dose of 1.0 microg/insect, but no toxicity was observed against mice even after injection of 1.0 microg of LaIT1 via the intracerebroventricular route, suggesting that the effect of the toxin is insect-selective. Edman sequencing and mass spectrometric analysis revealed that the toxin is composed of 36 amino acid residues and cross-linked by only two disulfide bridges. The pattern of the disulfide bridges was assigned by LC/MS analysis after enzymatic digestion. LaIT1 shows no sequence homology to any other known toxins, suggesting that this toxin represents a novel structural motif class.
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Affiliation(s)
- Nobuto Matsushita
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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25
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Abstract
Antipsychotic drugs are thought to exert their therapeutic action by antagonizing dopamine receptors but are also known to produce side effects in the heart by inhibiting cardiac ether-a-go-go-related gene (ERG) K(+) channels. Recently, it has been discovered that the same channels are present in the brain, including midbrain dopamine neurons. ERG channels are most active after the cessation of intense electrical activity, and blockade of these channels prolongs plateau potentials in bursting dopamine neurons. This change in excitability would be expected to alter dopamine release. Therefore, the therapeutic action of antipsychotic drugs may depend on inhibition of both postsynaptic dopamine receptors and presynaptic ERG K(+) channels.
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Affiliation(s)
- Paul D Shepard
- Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD 21228, USA.
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26
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Clement H, Odell G, Zamudio FZ, Redaelli E, Wanke E, Alagón A, Possani LD. Isolation and characterization of a novel toxin from the venom of the spider Grammostola rosea that blocks sodium channels. Toxicon 2007; 50:65-74. [PMID: 17418351 DOI: 10.1016/j.toxicon.2007.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2007] [Indexed: 11/19/2022]
Abstract
This communication reports the chemical and physiological characterization of a novel peptide (GrTx1) isolated from the venom of the "rosean-tarantula"Grammostola rosea. This component was one among more than 15 distinct components separated from the soluble venom by high-performance liquid chromatography (HPLC). GrTx1 has 29 amino-acid residues, compactly folded by three disulfide bridges with a molecular weight of 3697 Da. Here we show that this peptide blocks Na(+) currents of neuroblastoma F-11 cells with an IC(50) of 2.8+/-0.1 microM, up to a maximum of about 85% at 10 microM. Moreover, the right-shift (+20.1+/-0.4 mV) of the fractional voltage-dependent conductance could be also compatible with a putative "gating-modifier" mechanism. No effects were seen on common K(+) channels, such as K(v)1.1 and 1.4, using concentrations of toxin up to 10 microM. Sequence analysis reveals that GrTx1 is closely related to other spider toxins reported to affect various distinct ion channel functions. A critical analysis of this study suggests the necessity to search for other potential receptor sites in order to establish the preferred specificity of these kind of peptides.
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Affiliation(s)
- Herlinda Clement
- Instituto de Biotecnologia-Universidad Nacional Autónoma de México-UNAM, Avenida Universidad, 2001 Apartado Postal 510-3, Cuernavaca, Morelos 62210, México
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