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Maatoug S, Cheikh A, Khamessi O, Tabka H, Landoulsi Z, Guigonis JM, Diochot S, Bendahhou S, Benkhalifa R. Cross Pharmacological, Biochemical and Computational Studies of a Human Kv3.1b Inhibitor from Androctonus australis Venom. Int J Mol Sci 2021; 22:ijms222212290. [PMID: 34830172 PMCID: PMC8618407 DOI: 10.3390/ijms222212290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/05/2021] [Accepted: 11/11/2021] [Indexed: 11/23/2022] Open
Abstract
The voltage-gated K+ channels Kv3.1 display fast activation and deactivation kinetics and are known to have a crucial contribution to the fast-spiking phenotype of certain neurons. AahG50, as a natural product extracted from Androctonus australis hector venom, inhibits selectively Kv3.1 channels. In the present study, we focused on the biochemical and pharmacological characterization of the component in AahG50 scorpion venom that potently and selectively blocks the Kv3.1 channels. We used a combined optimization through advanced biochemical purification and patch-clamp screening steps to characterize the peptide in AahG50 active on Kv3.1 channels. We described the inhibitory effect of a toxin on Kv3.1 unitary current in black lipid bilayers. In silico, docking experiments are used to study the molecular details of the binding. We identified the first scorpion venom peptide inhibiting Kv3.1 current at 170 nM. This toxin is the alpha-KTx 15.1, which occludes the Kv3.1 channel pore by means of the lysine 27 lateral chain. This study highlights, for the first time, the modulation of the Kv3.1 by alpha-KTx 15.1, which could be an interesting starting compound for developing therapeutic biomolecules against Kv3.1-associated diseases.
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Affiliation(s)
- Sonia Maatoug
- Laboratoire Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia; (A.C.); (H.T.); (Z.L.)
- Correspondence: (S.M.); (R.B.); Tel.: +216-98-81-27-32 (R.B.)
| | - Amani Cheikh
- Laboratoire Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia; (A.C.); (H.T.); (Z.L.)
| | - Oussema Khamessi
- Laboratoire des Biomolécules Thérapeutiques, Institut Pasteur de Tunis, Université de Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia;
| | - Hager Tabka
- Laboratoire Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia; (A.C.); (H.T.); (Z.L.)
- Faculté des Sciences de Bizerte, Université de Carthage, Bizerte 7021, Tunisia
| | - Zied Landoulsi
- Laboratoire Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia; (A.C.); (H.T.); (Z.L.)
| | - Jean-Marie Guigonis
- Laboratory Transporter in Imaging and Radiotherapy in Oncology (TIRO), Direction de la Recherche Fondamentale (DRF), Institut des Sciences du Vivant Fréderic Joliot, Commissariat à l′Energie Atomique et aux Énergies Alternatives (CEA), Université Côte d’Azur, F-06107 Nice, France;
| | - Sylvie Diochot
- Institut de Pharmacologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Université Côte d’Azur, 660 Route des Lucioles, Sophia-Antipolis, 06560 Valbonne, France;
| | - Saïd Bendahhou
- UMR7370 CNRS, LP2M, Université Côte d’Azur, Labex ICST, Nice, France;
| | - Rym Benkhalifa
- Laboratoire Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia; (A.C.); (H.T.); (Z.L.)
- Correspondence: (S.M.); (R.B.); Tel.: +216-98-81-27-32 (R.B.)
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Jaouadi H, Bouyacoub Y, Chabrak S, Kraoua L, Zaroui A, Elouej S, Nagara M, Dallali H, Delague V, Levy N, Benkhalifa R, Mechmeche R, Zaffran S, Abdelhak S. Multiallelic rare variants support an oligogenic origin of sudden cardiac death in the young. Herz 2020; 46:94-102. [PMID: 31970460 DOI: 10.1007/s00059-019-04883-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/20/2019] [Accepted: 12/06/2019] [Indexed: 12/16/2022]
Abstract
Unexplained sudden death in the young is cardiovascular in most cases. Structural and conduction defects in cardiac-related genes can conspire to underlie sudden cardiac death. Here we report a clinical investigation and an extensive genetic assessment of a Tunisian family with sudden cardiac death in young members. In order to identify the family-genetic basis of sudden cardiac death, we performed Whole Exome Sequencing (WES), read depth copy-number-variation (CNV) screening and segregation analysis. We identify 6 ultra-rare pathogenic heterozygous variants in OBSCN, RYR2, DSC2, AKAP9, CACNA1C and RBM20 genes, and one homozygous splicing variant in TECRL gene consistent with an oligogenic model of inheritance. CNV analysis did not reveal any causative CNV consistent with the family phenotype. Overall, our results are highly suggestive for a cumulative effect of heterozygous missense variants as disease causation and to account for a greater disease severity among offspring. Our study further confirms the complexity of the inheritance of sudden cardiac death and highlights the utility of family-based WES and segregation analysis in the identification of family specific mutations within different cardiac genes pathways.
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Affiliation(s)
- Hager Jaouadi
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur, BP74-1002, Tunis, belvédère, Tunisia.
| | - Yosra Bouyacoub
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur, BP74-1002, Tunis, belvédère, Tunisia
| | - Sonia Chabrak
- Department of Cardiology, La Rabta Hospital, Tunis, Tunisia.,Faculty of Medicine of Tunis, Université Tunis El Manar, Tunis, Tunisia
| | - Lilia Kraoua
- Department of Congenital and Hereditary Diseases, Charles Nicolle Hospital, Tunis, Tunisia
| | - Amira Zaroui
- Faculty of Medicine of Tunis, Université Tunis El Manar, Tunis, Tunisia
| | - Sahar Elouej
- Aix Marseille University, INSERM, U1251, Marseille Medical Genetics, Marseille, France
| | - Majdi Nagara
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur, BP74-1002, Tunis, belvédère, Tunisia
| | - Hamza Dallali
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur, BP74-1002, Tunis, belvédère, Tunisia
| | - Valérie Delague
- Aix Marseille University, INSERM, U1251, Marseille Medical Genetics, Marseille, France
| | - Nicolas Levy
- Aix Marseille University, INSERM, U1251, Marseille Medical Genetics, Marseille, France
| | - Rym Benkhalifa
- Venoms and Therapeutic Biomolecules Laboratory LR16IPT08, Institut Pasteur de Tunis, Tunis, Tunisia
| | - Rachid Mechmeche
- Department of Cardiology, La Rabta Hospital, Tunis, Tunisia.,Faculty of Medicine of Tunis, Université Tunis El Manar, Tunis, Tunisia
| | - Stéphane Zaffran
- Aix Marseille University, INSERM, U1251, Marseille Medical Genetics, Marseille, France
| | - Sonia Abdelhak
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur, BP74-1002, Tunis, belvédère, Tunisia
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3
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Cheikh A, Tabka H, Tlili Y, Santulli A, Bouzouaya N, Bouhaouala-Zahar B, Benkhalifa R. Xenopus Oocyte's Conductance for Bioactive Compounds Screening and Characterization. Int J Mol Sci 2019; 20:ijms20092083. [PMID: 31035589 PMCID: PMC6539028 DOI: 10.3390/ijms20092083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 12/23/2022] Open
Abstract
Background: Astaxanthin (ATX) is a lipophilic compound found in many marine organisms. Studies have shown that ATX has many strong biological properties, including antioxidant, antiviral, anticancer, cardiovascular, anti-inflammatory, neuro-protective and anti-diabetic activities. However, no research has elucidated the effect of ATX on ionic channels. ATX can be extracted from shrimp by-products. Our work aims to characterize ATX cell targets to lend value to marine by-products. Methods: We used the Xenopus oocytes cell model to characterize the pharmacological target of ATX among endogenous Xenopus oocytes’ ionic channels and to analyze the effects of all carotenoid-extract samples prepared from shrimp by-products using a supercritical fluid extraction (SFE) method. Results: ATX inhibits amiloride-sensitive sodium conductance, xINa, in a dose-dependent manner with an IC50 of 0.14 µg, a maximum inhibition of 75% and a Hill coefficient of 0.68. It does not affect the potential of half activation, but significantly changes the kinetics, according to the slope factor values. The marine extract prepared from shrimp waste at 10 µg inhibits xINa in the same way as ATX 0.1 µg does. When ATX was added to the entire extract at 10 µg, inhibition reached that induced with ATX 1 µg. Conclusions: ATX and the shrimp Extract inhibit amiloride-sensitive sodium channels in Xenopus oocytes and the TEVC method makes it possible to measure the ATX inhibitory effect in bioactive SFE-Extract samples.
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Affiliation(s)
- Amani Cheikh
- Laboratoire Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia.
| | - Hager Tabka
- Laboratoire Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia.
| | - Yassine Tlili
- Laboratoire Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia.
| | - Andrea Santulli
- Laboratorio di Biochimica Marina ed ecotossicologia, Dipartimento di Scienze della Terra e del Mare, Università degli Studi di Palermo, 91100 Trapani, Italy.
| | | | - Balkiss Bouhaouala-Zahar
- Laboratoire Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia.
- Faculté de Médecine de Tunis, Université Tunis El Manar, 15 Rue Djebel Lakhdhar, La Rabta, Tunis 1007, Tunisia.
| | - Rym Benkhalifa
- Laboratoire Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, Université Tunis El Manar, 13 Place Pasteur BP74, Tunis 1002, Tunisia.
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Jaouadi H, Zaouak A, Sellami K, Messaoud O, Chargui M, Hammami H, Jones M, Jouini R, Chadli Debbiche A, Chraiet K, Fenniche S, Mrad R, Mokni M, Turki H, Benkhalifa R, Abdelhak S. H syndrome: Clinical, histological and genetic investigation in Tunisian patients. J Dermatol 2018; 45:978-985. [PMID: 29808591 DOI: 10.1111/1346-8138.14359] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022]
Abstract
H syndrome is a rare autosomal recessive disorder with characteristic dermatological findings consisting of hyperpigmentation and hypertrichosis patches mainly located on the inner thighs and multisystemic involvement including hepatosplenomegaly, hearing loss, heart abnormalities and hypogonadism. The aim of this study was to conduct a clinical and genetic investigation in five unrelated Tunisian patients with suspected H syndrome. Hence, genetic analysis of the SLC29A3 gene was performed for four patients with a clinical diagnosis of H syndrome. We identified a novel frame-shift mutation in the SLC29A3 gene in a female patient with a severe clinical presentation. Furthermore, we report two mutations previously described, the p.R363Q mutation in a male patient and the p.P324L mutation in two patients of different age and sex. This paper extends the mutation spectrum of H syndrome by reporting a novel frame-shift mutation, the p.S15Pfs*86 in exon 2 of SLC29A3 gene and emphasizes the relevance of genetic testing for its considerable implications in early diagnosis and clinical management.
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Affiliation(s)
- Hager Jaouadi
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
| | - Anissa Zaouak
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia.,Department of Dermatology, Habib Thameur Hospital, Tunis, Tunisia
| | - Khadija Sellami
- Department of Dermatology, Hedi Chaker Hospital, Sfax, Tunisia
| | - Olfa Messaoud
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
| | - Mariem Chargui
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
| | - Houda Hammami
- Department of Dermatology, Habib Thameur Hospital, Tunis, Tunisia
| | - Meriem Jones
- Department of Dermatology, Charles Nicolle Hospital, Tunis, Tunisia
| | - Raja Jouini
- Department of Pathology, Habib Thameur Hospital, Tunis, Tunisia
| | | | - Karima Chraiet
- Department of Pediatrics, Mohamed Tahar Maamouri Hospital, Nabeul, Tunisia
| | - Sami Fenniche
- Department of Dermatology, Habib Thameur Hospital, Tunis, Tunisia
| | - Ridha Mrad
- Department of Congenital and Hereditary Diseases, Charles Nicolle Hospital, Tunis, Tunisia
| | - Mourad Mokni
- Department of Dermatology, La Rabta Hospital, Tunis, Tunisia
| | - Hamida Turki
- Department of Dermatology, Hedi Chaker Hospital, Sfax, Tunisia
| | - Rym Benkhalifa
- Venoms and Therapeutic Biomolecules Laboratory LR16IPT08, Pasteur Institute of Tunis, Tunis, Tunisia
| | - Sonia Abdelhak
- Biomedical Genomics and Oncogenetics Laboratory LR16IPT05, Pasteur Institute of Tunis, Tunis El Manar University, Tunis, Tunisia
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Landoulsi Z, Miceli F, Palmese A, Amoresano A, Marino G, El Ayeb M, Taglialatela M, Benkhalifa R. 23. A novel toxin variant from the Androctonus australis hector scorpion venom selectively activates Kv7.4 channel. Toxicon 2014. [DOI: 10.1016/j.toxicon.2014.08.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Landoulsi Z, Miceli F, Palmese A, Amoresano A, Marino G, El Ayeb M, Taglialatela M, Benkhalifa R. Subtype-selective activation of K(v)7 channels by AaTXKβ₂₋₆₄, a novel toxin variant from the Androctonus australis scorpion venom. Mol Pharmacol 2013; 84:763-73. [PMID: 24019223 DOI: 10.1124/mol.113.088971] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
K(v)7.4 channel subunits are expressed in central auditory pathways and in inner ear sensory hair cells and skeletal and smooth muscle cells. Openers of K(v)7.4 channels have been suggested to improve hearing loss, systemic or pulmonary arterial hypertension, urinary incontinence, gastrointestinal and neuropsychiatric diseases, and skeletal muscle disorders. Scorpion venoms are a large source of peptides active on K⁺ channels. Therefore, we have optimized a combined purification/screening procedure to identify specific modulator(s) of K(v)7.4 channels from the venom of the North African scorpion Androctonus australis (Aa). We report the isolation and functional characterization of AaTXKβ₂₋₆₄, a novel variant of AaTXKβ₁₋₆₄, in a high-performance liquid chromatography fraction from Aa venom (named P8), which acts as the first peptide activator of K(v)7.4 channels. In particular, in both Xenopus oocytes and mammalian Chinese hamster ovary cells, AaTXKβ₂₋₆₄, but not AaTXKβ₁₋₆₄, hyperpolarized the threshold voltage of current activation and increased the maximal currents of heterologously expressed K(v)7.4 channels. AaTXKβ₂₋₆₄ also activated K(v)7.3, K(v)7.2/3, and K(v)7.5/3 channels, whereas homomeric K(v)1.1, K(v)7.1, and K(v)7.2 channels were unaffected. We anticipate that these results may prove useful in unraveling the novel biologic roles of AaTXKβ₂₋₆₄-sensitive K(v)7 channels and developing novel pharmacologic tools that allow subtype-selective targeting of K(v)7 channels.
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Affiliation(s)
- Zied Landoulsi
- Laboratoire des Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, Université Tunis-El Manar, Tunis-Belvédère, Tunisia (Z.L., M.E.A., R.B.); Division of Pharmacology, Department of Neuroscience, University of Naples Federico II, Naples, Italy (F.M., M.T.); Department of Chemical Sciences, University of Naples Federico II, Naples, Italy (A.P., A.A., G.M.); Department of Medicine and Health Science, University of Molise, Campobasso, Italy (M.T.); and Unidad de Biofísica, Consejo Superior de Investigaciones Cientificas, Universidad del Pais Vasco, Leioa, Spain (M.T.)
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Cheikh A, Benkhalifa R, Landoulsi Z, Chatti I, Ayeb ME. Inhibition of human Kv3.1 current expressed in Xenopus oocytes by the toxic venom fraction of Androctonus australis hector. Arch Pharm Res 2013; 37:1445-53. [PMID: 23771502 DOI: 10.1007/s12272-013-0176-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 06/03/2013] [Indexed: 10/26/2022]
Abstract
AahG50, the toxic fraction of Androctonus australis hector venom, was studied on human Kv3.1 channels activation, stably expressed in Xenopus oocytes using the two-electrode voltage clamp technique. AahG50 reduced Kv3.1 currents in a reversible concentration-dependent manner, with an IC50 value and a Hill coefficient of 40.4 ± 0.2 μg/ml and 1.3 ± 0.05, respectively. AahG50 inhibited IKv3.1 without modifying the current activation kinetics. The AahG50-induced inhibition of Kv3.1 channels was voltage-dependent, with a gradual increase at lower concentrations and over the voltage range of channels opening. However, at higher concentrations, the inhibition exhibited voltage dependence only in the first range of channels opening from -20 to +10 mV, but demonstrates a low degree of voltage-dependence when channels are fully activated. In the literature, toxins have previously been isolated from AahG50, KAaH1 and KAaH2 and were reported not to have any effect on IKv3.1. The present article's findings suggest that AahG50 may contain a peptidic component active on Kv3.1 channels, which inhibits IKv3.1 in a selective manner.
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Affiliation(s)
- Amani Cheikh
- Laboratoire des Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, BP 74, 1002, Tunis, Tunisia,
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Srairi-Abid N, Shahbazzadeh D, Chatti I, Mlayah-Bellalouna S, Mejdoub H, Borchani L, Benkhalifa R, Akbari A, El Ayeb M. Hemitoxin, the first potassium channel toxin from the venom of the Iranian scorpion Hemiscorpius lepturus. FEBS J 2008; 275:4641-50. [DOI: 10.1111/j.1742-4658.2008.06607.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Cheikh A, Cognard C, Potreau D, Bescond J, Raymond G, El Ayeb M, Benkhalifa R. [Modulation of skeletal muscle contraction by the non-toxic fraction of Buthus occitanus tunetanus venom via the cholinergic receptors]. Arch Inst Pasteur Tunis 2007; 84:39-47. [PMID: 19388582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cholinergic receptors have an essential physiological role in the central nervous system because of their implication in higher functions in the neuromuscular junction within the brain and also in the peripheral nervous system by activating nicotinic (nAChRs) or muscarinic (mAChRs) receptors. Moreover, cholinergic receptors could be recognized by animal toxins isolated from snake venoms or alkaloids having animal or vegetal origin. In this context, we aim to find such molecules in a non toxic venom fraction of Buthus occitanus tunetanus scorpion, M1, which could therefore constitute promising medical tool. We present here a physiological study in skeletal muscle cells that regroups data that have been recently published and some new results reinforcing the last ones. The global effect of M1, was firstly studied on isolated nerve-muscle preparation. In cultured myotubes, we have found that the intracellular calcium increase, induced by M1 was blocked when ryanodine or inositol 1,4,5-triphosphate receptors are inhibited. Moreover, we have shown that M1 application on myotubes, induced a membrane depolarization as seen with acetylcholine. The treatment of myotubes with alpha-bungarotoxin blocked in most parts the depolarization amplitude. Thus, these results confirm the presence of at least one component in M1 active in nAChRs.
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Affiliation(s)
- A Cheikh
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, BP 74-1002 Tunis, Tunisie
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Cheikh A, Benkhalifa R, Potreau D, Raymond G, El Ayeb M, Cognard C. A novel depolarizing activity of scorpion venom fraction M1 due to activation of skeletal muscle nicotinic receptors. Toxicon 2007; 49:117-22. [PMID: 17069869 DOI: 10.1016/j.toxicon.2006.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 09/08/2006] [Accepted: 09/12/2006] [Indexed: 10/24/2022]
Abstract
A depolarizing activity following interaction with nicotinic acetylcholine receptors (nAchRs) in skeletal muscle cells, was observed for the first time in the non-toxic venom fraction (M1) of the yellow scorpion Buthus occitanus tunetanus (Bot). The effects of M1 fraction were tested on cultured rat myotubes by recording changes in [Ca2+]i. When applied, M1 (10 microg/mL) induced a transient increase of [Ca2+]i which could be blocked by a prior application of alpha-Bungarotoxin (alpha-Bg-Tx).
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Affiliation(s)
- Amani Cheikh
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, Tunis BP 74-1002, Tunisia
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Cheikh A, Benkhalifa R, Bescond J, El Ayeb M, Raymond G, Cognard C, Potreau D. Depression of cardiac L-type calcium current by a scorpion venom fraction M1 following muscarinic receptors interaction involving adenylate cyclase pathway. Toxicon 2006; 48:373-87. [PMID: 16904145 DOI: 10.1016/j.toxicon.2006.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 06/20/2006] [Accepted: 06/22/2006] [Indexed: 11/21/2022]
Abstract
The effects of a non-toxic fraction, called M1, from Buthus occitanus tunetanus (Bot) scorpion were studied on rat cardiac contraction and calcium transient and current. A decrease in both rate and tension on isolated intact hearts as well as in calcium transient induced by depolarizing 100 K(+) solution on isolated ventricular cardiomyocytes was firstly observed. Studies with the whole cell patch clamp method showed that M1 decreased the L-type calcium current (ICa(L)) in a dose-dependent manner with an IC50 of 0.36 microg/mL and a Hill coefficient of 0.95. This effect was blocked and reversed by the specific muscarinic receptors antagonist atropine, 1 microM, and was completely prevented when cardiomyocytes were pretreated with Pertussis toxin, 1 microg/mL, to block the alpha subunit of the PTX-sensitive G proteins. These results show that M1 fraction of Bot inhibits basal calcium current by interacting with muscarinic receptors and suggest that this inhibition could be attributed to inhibition of adenylate cyclase activity by a mechanism involving PTX-sensitive G proteins.
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Affiliation(s)
- Amani Cheikh
- Laboratoire Venins et Toxines, Institut Pasteur de Tunis, BP 74-1002, Tunis, Tunisia
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Srairi-Abid N, Guijarro JI, Benkhalifa R, Mantegazza M, Cheikh A, Ben Aissa M, Haumont PY, Delepierre M, El Ayeb M. A new type of scorpion Na+-channel-toxin-like polypeptide active on K+ channels. Biochem J 2005; 388:455-64. [PMID: 15656785 PMCID: PMC1138952 DOI: 10.1042/bj20041407] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have purified and characterized two peptides, named KAaH1 and KAaH2 (AaH polypeptides 1 and 2 active on K+ channels, where AaH stands for Androctonus australis Hector), from the venom of A. australis Hector scorpions. Their sequences contain 58 amino acids including six half-cysteines and differ only at positions 26 (Phe/Ser) and 29 (Lys/Gln). Although KAaH1 and KAaH2 show important sequence similarity with anti-mammal beta toxins specific for voltage-gated Na+ channels, only weak beta-like effects were observed when KAaH1 or KAaH2 (1 microM) were tested on brain Nav1.2 channels. In contrast, KAaH1 blocks Kv1.1 and Kv1.3 channels expressed in Xenopus oocytes with IC50 values of 5 and 50 nM respectively, whereas KAaH2 blocks only 20% of the current on Kv1.1 and is not active on Kv1.3 channels at a 100 nM concentration. KAaH1 is thus the first member of a new subfamily of long-chain toxins mainly active on voltage-gated K+ channels. NMR spectra of KAaH1 and KAaH2 show good dispersion of signals but broad lines and poor quality. Self-diffusion NMR experiments indicate that lines are broadened due to a conformational exchange on the millisecond time scale. NMR and CD indicate that both polypeptides adopt a similar fold with alpha-helical and b-sheet structures. Homology-based molecular models generated for KAaH1 and KAaH2 are in accordance with CD and NMR data. In the model of KAaH1, the functionally important residues Phe26 and Lys29 are close to each other and are located in the alpha-helix. These residues may constitute the so-called functional dyad observed for short alpha-KTx scorpion toxins in the beta-sheet.
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Affiliation(s)
- Najet Srairi-Abid
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, 13, place Pasteur, BP-74 Tunis 1002, Tunisia.
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Mejri T, Borchani L, Srairi-Abid N, Benkhalifa R, Cestele S, Regaya I, Karoui H, Pelhate M, Rochat H, El Ayeb M. BotIT6: a potent depressant insect toxin from Buthus occitanus tunetanus venom. Toxicon 2003; 41:163-71. [PMID: 12565735 DOI: 10.1016/s0041-0101(02)00246-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A new depressant insect toxin Buthus occitanus tunetanus insect-toxin 6 (BotIT6) was purified by high-performance liquid chromatography from Buthus occitanus tunetanus (Bot) venom. BotIT6 is very active against Blatella germanica (LD50=10ng/100mg body mass) thus being one of the most potent anti-insect toxin so far characterised. When compared to other insect toxin sequences, BotIT6 present high similarities with depressant insect toxins with an additional arginine residue at the C-terminus and a methionine at position 27. The calculated net charge of BotIT6 is positive (+3) whereas it is negative for classical depressant toxins: this might be associated with its high toxicity. Voltage current clump studies show that BotIT6 is not a very potent depressant insect toxin despite its high toxicity in vivo. BotIT6 is able to fully inhibit the specific binding of 125I AaHIT and 125I-BotIT2 on Periplaneta americana synaptosomal membrane vesicles with high affinities. Despite its higher toxicity BotIT6 is a weaker competitor with 125I AaHIT and 125I BotIT2 as compared to the other beta toxins.Altogether, these results may suggest that BotIT6 probably defines a novel sub-group of depressant anti-insect toxins for which the receptor site can be overlapping, but not identical to that for classical depressant insect toxins.
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Affiliation(s)
- Thouraya Mejri
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, BP 74-1002, Tunis, Tunisia.
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Bouhaouala-Zahar B, Benkhalifa R, Srairi N, Zenouaki I, Ligny-Lemaire C, Drevet P, Sampieri F, Pelhate M, El Ayeb M, Ménez A, Karoui H, Ducancel F. A chimeric scorpion alpha-toxin displays de novo electrophysiological properties similar to those of alpha-like toxins. Eur J Biochem 2002; 269:2831-41. [PMID: 12071945 DOI: 10.1046/j.1432-1033.2002.02918.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BotXIV and LqhalphaIT are two structurally related long chain scorpion alpha-toxins that inhibit sodium current inactivation in excitable cells. However, while LqhalphaIT from Leiurus quinquestriatus hebraeus is classified as a true and strong insect alpha-toxin, BotXIV from Buthus occitanus tunetanus is characterized by moderate biological activities. To assess the possibility that structural differences between these two molecules could reflect the localization of particular functional topographies, we compared their sequences. Three structurally deviating segments located in three distinct and exposed loops were identified. They correspond to residues 8-10, 19-22, and 38-43. To evaluate their functional role, three BotXIV/LqhalphaIT chimeras were designed by transferring the corresponding LqhalphaIT sequences into BotXIV. Structural and antigenic characterizations of the resulting recombinant chimera show that BotXIV can accommodate the imposed modifications, confirming the structural flexibility of that particular alpha/beta fold. Interestingly, substitution of residues 8-10 yields to a new electrophysiological profile of the corresponding variant, partially comparable to that one of alpha-like scorpion toxins. Taken together, these results suggest that even limited structural deviations can reflect functional diversity, and also that the structure-function relationships between insect alpha-toxins and alpha-like scorpion toxins are probably more complex than expected.
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Stankiewicz M, Hamon A, Benkhalifa R, Kadziela W, Hue B, Lucas S, Mebs D, Pelhate M. Effects of a centipede venom fraction on insect nervous system, a native Xenopus oocyte receptor and on an expressed Drosophila muscarinic receptor. Toxicon 1999; 37:1431-45. [PMID: 10414867 DOI: 10.1016/s0041-0101(99)00089-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Centipede venoms are complex protein mixtures; very few is known about their pharmacological actions. Application of a Scolopendra sp. venom fraction (SC1) on the cockroach giant axon induced an increase in the leak current correlated with a decrease in the membrane resistance, suggesting the presence in SC1 of components opening non-specific pores in the axonal membrane. On a cockroach central cholinergic synapse, microinjection of SC1 induced a small transient depolarization of the postsynaptic membrane, followed by a slow stable depolarization and a drastic decrease in the evoked subthreshold excitatory postsynaptic potential amplitude. A pretreatment of the ganglion with atropine or scopolamine reduced the amplitude of the SC1-induced depolarizing wave, suggesting a possible cholinergic muscarinic target. On control Xenopus oocytes, SC1 induced an inward oscillatory Ca2(+)-dependent Cl- current mediated through the activation of native lysophosphatidic acid receptors (LPAr). Indeed, pretreatment of oocytes with 1 microM N-palmitoyl-tyrosine phosphoric acid, a selective competitive antagonist of LPAr, decreased responses to SC1 by 70%. Application of SC1 to oocytes expressing a cloned Drosophila muscarinic receptor (Dml) induced a biphasic response comprising: (1) a large fast Cl- current that was abolished by pretreatment with atropine and scopolamine and (2) a slow and small oscillating Cl- current corresponding to the response observed in control oocytes. These observations confirm the presence of muscarinic agonists in SCI and reveal their direct action on an insect muscarinic receptor subtype homologous to mammalian M1-M3 receptors.
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Affiliation(s)
- M Stankiewicz
- Laboratory of Biophysics, Institute of General and Molecular Biology, N. Copernicus University, Torun, Poland
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Benkhalifa R, Stankiewicz M, Lapied B, Turkov M, Zilberberg N, Gurevitz M, Pelhate M. Refined electrophysiological analysis suggests that a depressant toxin is a sodium channel opener rather than a blocker. Life Sci 1997; 61:819-30. [PMID: 9275012 DOI: 10.1016/s0024-3205(97)00564-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of a recombinant depressant insect toxin from Leiurus quinquestriatus hebraeus, Lqh IT2-r, have been studied in current and voltage-clamp conditions on the isolated axonal and DUM neuron preparations of the cockroach Periplaneta americana. Lqh IT2-r depolarizes the axon, blocks the evoked action potentials, and modifies the amplitude and the kinetics of the sodium current. The inward transient peak current is greatly decreased and is followed by a maintained slow activating-deactivating sodium current. The slow component develops at membrane potentials more negative than the control, and has a time constant of activation of several tens of milliseconds. The flaccid properties of Lqh IT2-r do not correspond to a blockage of the Na+ channels, but may be attributed to modified Na+ channels which open at more negative potential, activate slowly and do not inactivate normally.
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Affiliation(s)
- R Benkhalifa
- Laboratory of Neurophysiology, CNRS EREA 120, University of Angers, France.
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