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Kingsbury M, Marteinson S, Ryall E, Hamoutene D. Considerations and data update for the inference of environmental quality standards for two avermectins widely used in salmon aquaculture. MARINE POLLUTION BULLETIN 2024; 201:116213. [PMID: 38460434 DOI: 10.1016/j.marpolbul.2024.116213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 02/27/2024] [Accepted: 02/28/2024] [Indexed: 03/11/2024]
Abstract
We have updated and reviewed toxicity data for Emamectin benzoate (EMB) and Ivermectin (IVER), two in-feed drugs used to treat sea lice in farmed Atlantic salmon, and inferred new Environmental Quality Standards (EQS) using a deterministic approach or Species Sensitivity Distributions (SSDs) based on available data. We used a SSD model averaging approach and inferred a water acute EQS value of 24.9 ng/L (SSD) for EMB, while previously established chronic water EQS of 0.17 ng/L and sediment benthic EQS of 131 ng/kg dry weight remained unchanged. For IVER, both a water acute EQS of 8.04 ng/L and a chronic water EQS of 3.98 ng/L were inferred using SSDs as well as a benthic EQS of 290 ng/kg dry weight using a deterministic approach. In light of the lack of solubility and tendency of both avermectins to sorb to material benthic EQSs remain the most relevant value to consider for regulators.
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Affiliation(s)
- M Kingsbury
- St. Andrews Biological Station, Fisheries and Oceans Canada, St. Andrews, NB E5B 0E4, Canada
| | - S Marteinson
- National Contaminants Advisory Group, Fisheries and Oceans Canada, Ottawa, ON K2P 2J8, Canada
| | - E Ryall
- Aquaculture, Biotechnology and Aquatic Animal Health Science Branch, Fisheries and Oceans Canada, ON K2P 2J8, Canada
| | - D Hamoutene
- St. Andrews Biological Station, Fisheries and Oceans Canada, St. Andrews, NB E5B 0E4, Canada.
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2
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Choudhary S, Abongwa M, Kashyap SS, Verma S, Mair GR, Kulke D, Martin RJ, Robertson AP. Nodulisporic acid produces direct activation and positive allosteric modulation of AVR-14B, a glutamate-gated chloride channel from adult Brugia malayi. Proc Natl Acad Sci U S A 2022; 119:e2111932119. [PMID: 35969762 PMCID: PMC9407656 DOI: 10.1073/pnas.2111932119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 06/13/2022] [Indexed: 11/18/2022] Open
Abstract
Glutamate-gated chloride channels (GluCls) are unique to invertebrates and are targeted by macrocyclic lactones. In this study, we cloned an AVR-14B GluCl subunit from adult Brugia malayi, a causative agent of lymphatic filariasis in humans. To elucidate this channel's pharmacological properties, we used Xenopus laevis oocytes for expression and performed two-electrode voltage-clamp electrophysiology. The receptor was gated by the natural ligand L-glutamate (effective concentration, 50% [EC50] = 0.4 mM) and ivermectin (IVM; EC50 = 1.8 nM). We also characterized the effects of nodulisporic acid (NA) on Bma-AVR-14B and NA-produced dual effects on the receptor as an agonist and a type II positive allosteric modulator. Here we report characterization of the complex activity of NA on a nematode GluCl. Bma-AVR-14B demonstrated some unique pharmacological characteristics. IVM did not produce potentiation of L-glutamate-mediated responses but instead, reduced the channel's sensitivity for the ligand. Further electrophysiological exploration showed that IVM (at a moderate concentration of 0.1 nM) functioned as an inhibitor of both agonist and positive allosteric modulatory effects of NA. This suggests that IVM and NA share a complex interaction. The pharmacological properties of Bma-AVR-14B indicate that the channel is an important target of IVM and NA. In addition, the unique electrophysiological characteristics of Bma-AVR-14B could explain the observed variation in drug sensitivities of various nematode parasites. We have also shown the inhibitory effects of IVM and NA on adult worm motility using Worminator. RNA interference (RNAi) knockdown suggests that AVR-14 plays a role in influencing locomotion in B. malayi.
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Affiliation(s)
- Shivani Choudhary
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Melanie Abongwa
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Sudhanva S. Kashyap
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Saurabh Verma
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Gunnar R. Mair
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Daniel Kulke
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Richard J. Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
| | - Alan P. Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011
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Structural mechanism underlying the differential effects of ivermectin and moxidectin on the C. elegans glutamate-gated chloride channel GLC-2. Biomed Pharmacother 2021; 145:112380. [PMID: 34749053 DOI: 10.1016/j.biopha.2021.112380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/19/2021] [Accepted: 10/25/2021] [Indexed: 11/02/2022] Open
Abstract
BACKGROUND AND PURPOSE Nematode glutamate-gated chloride channels (GluCls) are targets of ivermectin (IVM) and moxidectin (MOX), structurally dissimilar macrocyclic lactone (ML) anthelmintics. IVM and MOX possess different pharmacokinetics and efficacy profiles but are thought to have the same binding site, through which they allosterically activate GluCls, apart from the GLC-2 receptor, which is antagonized by IVM. Our goal was to determine GLC-2 sensitivity to MOX, investigate residues involved in antagonism of GLC-2, and to identify differences in receptor-level pharmacology between IVM and MOX. EXPERIMENTAL APPROACH Two-electrode voltage clamp electrophysiology was used to study the pharmacology of Caenorhabditis elegans GLC-2 receptors heterologously expressed in Xenopus laevis oocytes. In silico homology modeling identified Cel-GLC-2 residues Met291 and Gln292 at the IVM binding site that differ from other GluCls; we mutated these residues to those found in ML-sensitive GluCls, and those of filarial nematode GLC-2. KEY RESULTS We discovered that MOX inhibits wild-type C. elegans GLC-2 receptors roughly 10-fold more potently than IVM, and with greater maximal inhibition of glutamate activation (MOX = 86.9 ± 2.5%; IVM = 57.8 ± 5.9%). IVM was converted into an agonist in the Met291Gln mutant, but MOX remained an antagonist. Glutamate responses were abrogated in a Met291Leu Gln292Thr double mutant (mimicking filarial nematode GLC-2), but MOX and IVM were converted into positive allosteric modulators of glutamate at this construct. CONCLUSIONS AND IMPLICATIONS Our data provides new insights into differences in receptor-level pharmacology between IVM and MOX and identify residues responsible for ML antagonism of GLC-2.
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Moroz LL, Nikitin MA, Poličar PG, Kohn AB, Romanova DY. Evolution of glutamatergic signaling and synapses. Neuropharmacology 2021; 199:108740. [PMID: 34343611 PMCID: PMC9233959 DOI: 10.1016/j.neuropharm.2021.108740] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/13/2022]
Abstract
Glutamate (Glu) is the primary excitatory transmitter in the mammalian brain. But, we know little about the evolutionary history of this adaptation, including the selection of l-glutamate as a signaling molecule in the first place. Here, we used comparative metabolomics and genomic data to reconstruct the genealogy of glutamatergic signaling. The origin of Glu-mediated communications might be traced to primordial nitrogen and carbon metabolic pathways. The versatile chemistry of L-Glu placed this molecule at the crossroad of cellular biochemistry as one of the most abundant metabolites. From there, innovations multiplied. Many stress factors or injuries could increase extracellular glutamate concentration, which led to the development of modular molecular systems for its rapid sensing in bacteria and archaea. More than 20 evolutionarily distinct families of ionotropic glutamate receptors (iGluRs) have been identified in eukaryotes. The domain compositions of iGluRs correlate with the origins of multicellularity in eukaryotes. Although L-Glu was recruited as a neuro-muscular transmitter in the early-branching metazoans, it was predominantly a non-neuronal messenger, with a possibility that glutamatergic synapses evolved more than once. Furthermore, the molecular secretory complexity of glutamatergic synapses in invertebrates (e.g., Aplysia) can exceed their vertebrate counterparts. Comparative genomics also revealed 15+ subfamilies of iGluRs across Metazoa. However, most of this ancestral diversity had been lost in the vertebrate lineage, preserving AMPA, Kainate, Delta, and NMDA receptors. The widespread expansion of glutamate synapses in the cortical areas might be associated with the enhanced metabolic demands of the complex brain and compartmentalization of Glu signaling within modular neuronal ensembles.
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Affiliation(s)
- Leonid L Moroz
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, 32080, USA; Departments of Neuroscience and McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA.
| | - Mikhail A Nikitin
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119991, Russia; Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127994, Russia
| | - Pavlin G Poličar
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, 32080, USA; Faculty of Computer and Information Science, University of Ljubljana, SI-1000, Ljubljana, Slovenia
| | - Andrea B Kohn
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, 32080, USA
| | - Daria Y Romanova
- Cellular Neurobiology of Learning Lab, Institute of Higher Nervous Activity and Neurophysiology, Moscow, 117485, Russia.
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Miguel-Tomé S, Llinás RR. Broadening the definition of a nervous system to better understand the evolution of plants and animals. PLANT SIGNALING & BEHAVIOR 2021; 16:1927562. [PMID: 34120565 PMCID: PMC8331040 DOI: 10.1080/15592324.2021.1927562] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 05/10/2023]
Abstract
Most textbook definitions recognize only animals as having nervous systems. However, for the past couple decades, botanists have been meticulously studying long-distance signaling systems in plants, and some researchers have stated that plants have a simple nervous system. Thus, an academic conflict has emerged between those who defend and those who deny the existence of a nervous system in plants. This article analyses that debate, and we propose an alternative to answering yes or no: broadening the definition of a nervous system to include plants. We claim that a definition broader than the current one, which is based only on a phylogenetic viewpoint, would be helpful in obtaining a deeper understanding of how evolution has driven the features of signal generation, transmission and processing in multicellular beings. Also, we propose two possible definitions and exemplify how broader a definition allows for new viewpoints on the evolution of plants, animals and the nervous system.
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Affiliation(s)
- Sergio Miguel-Tomé
- Grupo De Investigación En Minería De Datos (Mida), Universidad De Salamanca, Salamanca, Spain
| | - Rodolfo R. Llinás
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
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Islam MS, Sana S, Haque ME, Rahman SM, Samad A, Al Noman A, Alam R, Rana S, Meem RI, Mondol D, Islam MS, Islam MT, Mazumder K. Methanol, ethyl acetate and n-hexane extracts of Tragia involucrata L. leaves exhibit anxiolytic, sedative and analgesic activity in Swiss albino mice. Heliyon 2021; 7:e05814. [PMID: 33426350 PMCID: PMC7785955 DOI: 10.1016/j.heliyon.2020.e05814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/22/2020] [Accepted: 12/18/2020] [Indexed: 10/28/2022] Open
Abstract
INTRODUCTION Tragia involucrata L. have been utilized as traditional medicine in Indian subcontinent for the treatment of numerous illnesses such as inflammation, pain and skin infection. In this current study we sought to assess the anxiolytic, sedative and analgesic activity of Tragia involucrata L. leaves extract. MATERIALS AND METHODS We first performed a phytochemical screening test of the leaves extracts following standard phytochemical screening protocols. We next examined the anxiolytic and sedative activity of crude methanol (TIME), ethyl acetate (TIEAE) and n-Hexane (TIHE) extract of Tragia involucrata L. leaves using mouse behavioral models such as elevated plus-maze test and pentobarbital-induced sleeping time test, respectively. Likewise, we evaluated the analgesic activity using acetic acid induced writhing test and formalin induced paw licking test. Additionally, we performed a quantitative analysis of heavy metals content of Tragia involucrata L. leaves by overnight digestion in concentrated nitric acid (HNO3). RESULTS Phytochemical screening demonstrated that TIME, TIEAE and TIHE contain flavonoids, alkaloids, tannins, phenols, terpenoids and sterols. Administration of these extracts resulted in higher number of open arm entry, lower number of close arm entry and higher time spent in open arm compared to control treatment (p < 0.05). Moreover, these treatments decreased the onset of sleep time and increased the duration of sleep compared to control treated mice (all p < 0.05). Likewise, extracts treated mice exhibited decreased number of writhing as well as lower acute phase and late phase duration compared to control treatment (all p < 0.05). The average level of As and Fe in Tragia involucrata L. leaves was 5.16 ± 0.012 ppm and 2.76 ± 0.015 ppm, respectively. CONCLUSION Results from this study support that Tragia involucrata L. leaves extracts exhibit an anxiolytic, sedative and analgesic activity in mice.
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Affiliation(s)
- Md. Shofiqul Islam
- Department of Genetic Engineering & Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Samiron Sana
- Pharmacy Discipline, Life Science School, Khulna University, Khulna, 9208, Bangladesh
- Department of Pharmacy, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Md. Ehsanul Haque
- Department of Genetic Engineering & Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - S.M. Mushiur Rahman
- Department of Pharmacy, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Abdus Samad
- Department of Genetic Engineering & Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Abdullah Al Noman
- Department of Genetic Engineering & Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Rahat Alam
- Department of Genetic Engineering & Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Sohel Rana
- Department of Pharmacy, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Rima Islam Meem
- Department of Genetic Engineering & Biotechnology, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Debashish Mondol
- Department of Pharmacy, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
| | - Md. Shariful Islam
- Department of Biochemistry and Molecular Biology, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh
| | - Md. Torikul Islam
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah, USA
- Institute of Nutrition and Food Science, University of Dhaka, Dhaka, Bangladesh
| | - Kishor Mazumder
- Department of Pharmacy, Faculty of Biological Science and Technology, Jashore University of Science and Technology, Jashore, 7408, Bangladesh
- School of Biomedical Science, Charles Sturt University, NSW, 2678, Australia
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Robertson RM, Dawson-Scully KD, Andrew RD. Neural shutdown under stress: an evolutionary perspective on spreading depolarization. J Neurophysiol 2020; 123:885-895. [PMID: 32023142 PMCID: PMC7099469 DOI: 10.1152/jn.00724.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 11/22/2022] Open
Abstract
Neural function depends on maintaining cellular membrane potentials as the basis for electrical signaling. Yet, in mammals and insects, neuronal and glial membrane potentials can reversibly depolarize to zero, shutting down neural function by the process of spreading depolarization (SD) that collapses the ion gradients across membranes. SD is not evident in all metazoan taxa with centralized nervous systems. We consider the occurrence and similarities of SD in different animals and suggest that it is an emergent property of nervous systems that have evolved to control complex behaviors requiring energetically expensive, rapid information processing in a tightly regulated extracellular environment. Whether SD is beneficial or not in mammals remains an open question. However, in insects, it is associated with the response to harsh environments and may provide an energetic advantage that improves the chances of survival. The remarkable similarity of SD in diverse taxa supports a model systems approach to understanding the mechanistic underpinning of human neuropathology associated with migraine, stroke, and traumatic brain injury.
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Affiliation(s)
- R Meldrum Robertson
- Department of Biology and Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - Ken D Dawson-Scully
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida
| | - R David Andrew
- Department of Biomedical and Molecular Sciences and Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
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Molina-Obando S, Vargas-Fique JF, Henning M, Gür B, Schladt TM, Akhtar J, Berger TK, Silies M. ON selectivity in the Drosophila visual system is a multisynaptic process involving both glutamatergic and GABAergic inhibition. eLife 2019; 8:e49373. [PMID: 31535971 PMCID: PMC6845231 DOI: 10.7554/elife.49373] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 09/18/2019] [Indexed: 01/06/2023] Open
Abstract
Sensory systems sequentially extract increasingly complex features. ON and OFF pathways, for example, encode increases or decreases of a stimulus from a common input. This ON/OFF pathway split is thought to occur at individual synaptic connections through a sign-inverting synapse in one of the pathways. Here, we show that ON selectivity is a multisynaptic process in the Drosophila visual system. A pharmacogenetics approach demonstrates that both glutamatergic inhibition through GluClα and GABAergic inhibition through Rdl mediate ON responses. Although neurons postsynaptic to the glutamatergic ON pathway input L1 lose all responses in GluClα mutants, they are resistant to a cell-type-specific loss of GluClα. This shows that ON selectivity is distributed across multiple synapses, and raises the possibility that cell-type-specific manipulations might reveal similar strategies in other sensory systems. Thus, sensory coding is more distributed than predicted by simple circuit motifs, allowing for robust neural processing.
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Affiliation(s)
- Sebastian Molina-Obando
- Institute of Developmental Biology and NeurobiologyJohannes Gutenberg-Universität MainzMainzGermany
- European Neuroscience Institute Göttingen – A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-SocietyGöttingenGermany
- International Max Planck Research School and Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB) at the University of GöttingenGöttingenGermany
| | - Juan Felipe Vargas-Fique
- Institute of Developmental Biology and NeurobiologyJohannes Gutenberg-Universität MainzMainzGermany
- European Neuroscience Institute Göttingen – A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-SocietyGöttingenGermany
- International Max Planck Research School and Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB) at the University of GöttingenGöttingenGermany
| | - Miriam Henning
- Institute of Developmental Biology and NeurobiologyJohannes Gutenberg-Universität MainzMainzGermany
- European Neuroscience Institute Göttingen – A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-SocietyGöttingenGermany
| | - Burak Gür
- Institute of Developmental Biology and NeurobiologyJohannes Gutenberg-Universität MainzMainzGermany
- European Neuroscience Institute Göttingen – A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-SocietyGöttingenGermany
- International Max Planck Research School and Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences (GGNB) at the University of GöttingenGöttingenGermany
| | - T Moritz Schladt
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (caesar)BonnGermany
| | - Junaid Akhtar
- Institute of Developmental Biology and NeurobiologyJohannes Gutenberg-Universität MainzMainzGermany
| | - Thomas K Berger
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (caesar)BonnGermany
- Institute of Physiology and PathophysiologyPhilipps-Universität MarburgMarburgGermany
| | - Marion Silies
- Institute of Developmental Biology and NeurobiologyJohannes Gutenberg-Universität MainzMainzGermany
- European Neuroscience Institute Göttingen – A Joint Initiative of the University Medical Center Göttingen and the Max-Planck-SocietyGöttingenGermany
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Abstract
Parasitic nematodes (roundworms) and platyhelminths (flatworms) cause debilitating chronic infections of humans and animals, decimate crop production and are a major impediment to socioeconomic development. Here we report a broad comparative study of 81 genomes of parasitic and non-parasitic worms. We have identified gene family births and hundreds of expanded gene families at key nodes in the phylogeny that are relevant to parasitism. Examples include gene families that modulate host immune responses, enable parasite migration though host tissues or allow the parasite to feed. We reveal extensive lineage-specific differences in core metabolism and protein families historically targeted for drug development. From an in silico screen, we have identified and prioritized new potential drug targets and compounds for testing. This comparative genomics resource provides a much-needed boost for the research community to understand and combat parasitic worms.
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Preza M, Montagne J, Costábile A, Iriarte A, Castillo E, Koziol U. Analysis of classical neurotransmitter markers in tapeworms: Evidence for extensive loss of neurotransmitter pathways. Int J Parasitol 2018; 48:979-992. [DOI: 10.1016/j.ijpara.2018.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 05/30/2018] [Accepted: 06/06/2018] [Indexed: 12/28/2022]
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Callau-Vázquez D, Pless SA, Lynagh T. Investigation of Agonist Recognition and Channel Properties in a Flatworm Glutamate-Gated Chloride Channel. Biochemistry 2018; 57:1360-1368. [PMID: 29411605 DOI: 10.1021/acs.biochem.7b01245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Glutamate-gated chloride channels (GluCls) are neurotransmitter receptors that mediate crucial inhibitory signaling in invertebrate neuromuscular systems. Their role in invertebrate physiology and their absence from vertebrates make GluCls a prime target for antiparasitic drugs. GluCls from flatworm parasites are substantially different from and are much less understood than those from roundworm and insect parasites, hindering the development of potential therapeutics targeting GluCls in flatworm-related diseases such as schistosomiasis. Here, we sought to dissect the molecular and chemical basis for ligand recognition in the extracellular glutamate binding site of SmGluCl-2 from Schistosoma mansoni, using site-directed mutagenesis, noncanonical amino acid incorporation, and electrophysiological recordings. Our results indicate that aromatic residues in ligand binding loops A, B, and C are important for SmGluCl-2 function. Loop C, which differs in length compared to other pentameric ligand-gated ion channels (pLGICs), contributes to ligand recognition through both an aromatic residue and two vicinal threonine residues. We also show that, in contrast to other pLGICs, the hydrophobic channel gate in SmGluCl-2 extends from the 9' position to the 6' position in the channel-forming M2 helix. The 6' and 9' positions also seem to control sensitivity to the pore blocker picrotoxin.
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Affiliation(s)
- Daniel Callau-Vázquez
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - Timothy Lynagh
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
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12
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The iNAPO Project: Biomimetic Nanopores for a New Generation of Lab-on-Chip Micro Sensors. ACTA ACUST UNITED AC 2018. [DOI: 10.11159/ijtan.2018.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Liebeskind BJ, Hofmann HA, Hillis DM, Zakon HH. Evolution of Animal Neural Systems. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2017. [DOI: 10.1146/annurev-ecolsys-110316-023048] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nervous systems are among the most spectacular products of evolution. Their provenance and evolution have been of interest and often the subjects of intense debate since the late nineteenth century. The genomics era has provided researchers with a new set of tools with which to study the early evolution of neurons, and recent progress on the molecular evolution of the first neurons has been both exciting and frustrating. It has become increasingly obvious that genomic data are often insufficient to reconstruct complex phenotypes in deep evolutionary time because too little is known about how gene function evolves over deep time. Therefore, additional functional data across the animal tree are a prerequisite to a fuller understanding of cell evolution. To this end, we review the functional modules of neurons and the evolution of their molecular components, and we introduce the idea of hierarchical molecular evolution.
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Affiliation(s)
- Benjamin J. Liebeskind
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
| | - Hans A. Hofmann
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - David M. Hillis
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
| | - Harold H. Zakon
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712
- Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, Texas 78712
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712
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Degani-Katzav N, Gortler R, Weissman M, Paas Y. Mutational Analysis at Intersubunit Interfaces of an Anionic Glutamate Receptor Reveals a Key Interaction Important for Channel Gating by Ivermectin. Front Mol Neurosci 2017; 10:92. [PMID: 28428744 PMCID: PMC5382172 DOI: 10.3389/fnmol.2017.00092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 03/17/2017] [Indexed: 11/13/2022] Open
Abstract
The broad-spectrum anthelmintic drug ivermectin (IVM) activates and stabilizes an open-channel conformation of invertebrate chloride-selective glutamate receptors (GluClRs), thereby causing a continuous inflow of chloride ions and sustained membrane hyperpolarization. These effects suppress nervous impulses and vital physiological processes in parasitic nematodes. The GluClRs are pentamers. Homopentameric receptors assembled from the Caenorhabditis elegans (C. elegans) GluClα (GLC-1) subunit can inherently respond to IVM but not to glutamate (the neurotransmitter). In contrast, heteromeric GluClα/β (GLC-1/GLC-2) assemblies respond to both ligands, independently of each other. Glutamate and IVM bind at the interface between adjacent subunits, far away from each other; glutamate in the extracellular ligand-binding domain, and IVM in the ion-channel pore periphery. To understand the importance of putative intersubunit contacts located outside the glutamate and IVM binding sites, we introduced mutations at intersubunit interfaces, between these two binding-site types. Then, we determined the effect of these mutations on the activation of the heteromeric mutant receptors by glutamate and IVM. Amongst these mutations, we characterized an α-subunit point mutation located close to the putative IVM-binding pocket, in the extracellular end of the first transmembrane helix (M1). This mutation (αF276A) moderately reduced the sensitivity of the heteromeric GluClαF276A/βWT receptor to glutamate, and slightly decreased the receptor subunits’ cooperativity in response to glutamate. In contrast, the αF276A mutation drastically reduced the sensitivity of the receptor to IVM and significantly increased the receptor subunits’ cooperativity in response to IVM. We suggest that this mutation reduces the efficacy of channel gating, and impairs the integrity of the IVM-binding pocket, likely by disrupting important interactions between the tip of M1 and the M2-M3 loop of an adjacent subunit. We hypothesize that this physical contact between M1 and the M2-M3 loop tunes the relative orientation of the ion-channel transmembrane helices M1, M2 and M3 to optimize pore opening. Interestingly, pre-exposure of the GluClαF276A/βWT mutant receptor to subthreshold IVM concentration recovered the receptor sensitivity to glutamate. We infer that IVM likely retained its positive modulation activity by constraining the transmembrane helices in a preopen orientation sensitive to glutamate, with no need for the aforementioned disrupted interactions between M1 and the M2-M3 loop.
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Affiliation(s)
- Nurit Degani-Katzav
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
| | - Revital Gortler
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
| | - Marina Weissman
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
| | - Yoav Paas
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences, Institute of Nanotechnology and Advanced Materials, Bar-Ilan UniversityRamat Gan, Israel
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Lynagh T, Komnatnyy VV, Pless SA. Unique Contributions of an Arginine Side Chain to Ligand Recognition in a Glutamate-gated Chloride Channel. J Biol Chem 2017; 292:3940-3946. [PMID: 28096462 PMCID: PMC5339774 DOI: 10.1074/jbc.m116.772939] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/11/2017] [Indexed: 11/06/2022] Open
Abstract
Glutamate recognition by neurotransmitter receptors often relies on Arg residues in the binding site, leading to the assumption that charge-charge interactions underlie ligand recognition. However, assessing the precise chemical contribution of Arg side chains to protein function and pharmacology has proven to be exceedingly difficult in such large and complex proteins. Using the in vivo nonsense suppression approach, we report the first successful incorporation of the isosteric, titratable Arg analog, canavanine, into a neurotransmitter receptor in a living cell, utilizing a glutamate-gated chloride channel from the nematode Haemonchus contortus Our data unveil a surprisingly small contribution of charge at a conserved arginine side chain previously suggested to form a salt bridge with the ligand, glutamate. Instead, our data show that Arg contributes crucially to ligand sensitivity via a hydrogen bond network, where Arg interacts both with agonist and with a conserved Thr side chain within the receptor. Together, the data provide a new explanation for the reliance of neurotransmitter receptors on Arg side chains and highlight the exceptional capacity of unnatural amino acid incorporation for increasing our understanding of ligand recognition.
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Affiliation(s)
- Timothy Lynagh
- From the Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, 2100 H Copenhagen, Denmark
| | - Vitaly V Komnatnyy
- From the Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, 2100 H Copenhagen, Denmark
| | - Stephan A Pless
- From the Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, 2100 H Copenhagen, Denmark
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16
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Degani-Katzav N, Klein M, Har-Even M, Gortler R, Tobi R, Paas Y. Trapping of ivermectin by a pentameric ligand-gated ion channel upon open-to-closed isomerization. Sci Rep 2017; 7:42481. [PMID: 28218274 PMCID: PMC5317004 DOI: 10.1038/srep42481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/11/2017] [Indexed: 11/09/2022] Open
Abstract
Ivermectin (IVM) is a broad-spectrum anthelmintic drug used to treat human parasitic diseases like river blindness and lymphatic filariasis. By activating invertebrate pentameric glutamate-gated chloride channels (GluCl receptors; GluClRs), IVM induces sustained chloride influx and long-lasting membrane hyperpolarization that inhibit neural excitation in nematodes. Although IVM activates the C. elegans heteromeric GluClα/β receptor, it cannot activate a homomeric receptor composed of the C. elegans GluClβ subunits. To understand this incapability, we generated a homopentameric α7-GluClβ chimeric receptor that consists of an extracellular ligand-binding domain of an α7 nicotinic acetylcholine receptor known to be potentiated by IVM, and a chloride-selective channel domain assembled from GluClβ subunits. Application of IVM prior to acetylcholine inhibited the responses of the chimeric α7-GluClβR. Adding IVM to activated α7-GluClβRs, considerably accelerated the decline of ACh-elicited currents and stabilized the receptors in a non-conducting state. Determination of IVM association and dissociation rate constants and recovery experiments suggest that, following initial IVM binding to open α7-GluClβRs, the drug induces a conformational change and locks the ion channel in a closed state for a long duration. We further found that IVM also inhibits the activation by glutamate of a homomeric receptor assembled from the C. elegans full-length GluClβ subunits.
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Affiliation(s)
- Nurit Degani-Katzav
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Moshe Klein
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Moran Har-Even
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Revital Gortler
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Ruthi Tobi
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Yoav Paas
- Laboratory of Ion Channels, The Mina and Everard Goodman Faculty of Life Sciences and The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel
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17
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Jaiteh M, Taly A, Hénin J. Evolution of Pentameric Ligand-Gated Ion Channels: Pro-Loop Receptors. PLoS One 2016; 11:e0151934. [PMID: 26986966 PMCID: PMC4795631 DOI: 10.1371/journal.pone.0151934] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 03/07/2016] [Indexed: 01/27/2023] Open
Abstract
Pentameric ligand-gated ion channels (pLGICs) are ubiquitous neurotransmitter receptors in Bilateria, with a small number of known prokaryotic homologues. Here we describe a new inventory and phylogenetic analysis of pLGIC genes across all kingdoms of life. Our main finding is a set of pLGIC genes in unicellular eukaryotes, some of which are metazoan-like Cys-loop receptors, and others devoid of Cys-loop cysteines, like their prokaryotic relatives. A number of such “Cys-less” receptors also appears in invertebrate metazoans. Together, those findings draw a new distribution of pLGICs in eukaryotes. A broader distribution of prokaryotic channels also emerges, including a major new archaeal taxon, Thaumarchaeota. More generally, pLGICs now appear nearly ubiquitous in major taxonomic groups except multicellular plants and fungi. However, pLGICs are sparsely present in unicellular taxa, suggesting a high rate of gene loss and a non-essential character, contrasting with their essential role as synaptic receptors of the bilaterian nervous system. Multiple alignments of these highly divergent sequences reveal a small number of conserved residues clustered at the interface between the extracellular and transmembrane domains. Only the “Cys-loop” proline is absolutely conserved, suggesting the more fitting name “Pro loop” for that motif, and “Pro-loop receptors” for the superfamily. The infered molecular phylogeny shows a Cys-loop and a Cys-less clade in eukaryotes, both containing metazoans and unicellular members. This suggests new hypotheses on the evolutionary history of the superfamily, such as a possible origin of the Cys-loop cysteines in an ancient unicellular eukaryote. Deeper phylogenetic relationships remain uncertain, particularly around the split between bacteria, archaea, and eukaryotes.
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Affiliation(s)
- Mariama Jaiteh
- Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, CNRS and Université Paris Diderot, Paris, France
| | - Antoine Taly
- Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, CNRS and Université Paris Diderot, Paris, France
| | - Jérôme Hénin
- Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, CNRS and Université Paris Diderot, Paris, France
- * E-mail:
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Liebeskind BJ, Hillis DM, Zakon HH, Hofmann HA. Complex Homology and the Evolution of Nervous Systems. Trends Ecol Evol 2015; 31:127-135. [PMID: 26746806 DOI: 10.1016/j.tree.2015.12.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/01/2015] [Accepted: 12/02/2015] [Indexed: 02/07/2023]
Abstract
We examine the complex evolution of animal nervous systems and discuss the ramifications of this complexity for inferring the nature of early animals. Although reconstructing the origins of nervous systems remains a central challenge in biology, and the phenotypic complexity of early animals remains controversial, a compelling picture is emerging. We now know that the nervous system and other key animal innovations contain a large degree of homoplasy, at least on the molecular level. Conflicting hypotheses about early nervous system evolution are due primarily to differences in the interpretation of this homoplasy. We highlight the need for explicit discussion of assumptions and discuss the limitations of current approaches for inferring ancient phenotypic states.
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Affiliation(s)
- Benjamin J Liebeskind
- Center for Systems and Synthetic Biology, University of Texas, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA; Center for Computational Biology and Bioinformatics, University of Texas, Austin, TX 78712.
| | - David M Hillis
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA; Center for Computational Biology and Bioinformatics, University of Texas, Austin, TX 78712; Department of Integrative Biology, University of Texas, Austin, TX 78712, USA
| | - Harold H Zakon
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA; Center for Computational Biology and Bioinformatics, University of Texas, Austin, TX 78712; Department of Integrative Biology, University of Texas, Austin, TX 78712, USA; Department of Neuroscience, University of Texas, Austin, TX 78712, USA; Institute for Neuroscience, University of Texas, Austin, TX 78712, USA; Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Hans A Hofmann
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA; Center for Computational Biology and Bioinformatics, University of Texas, Austin, TX 78712; Department of Integrative Biology, University of Texas, Austin, TX 78712, USA; Department of Neuroscience, University of Texas, Austin, TX 78712, USA; Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
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Transcriptome Analysis of the Central and Peripheral Nervous Systems of the Spider Cupiennius salei Reveals Multiple Putative Cys-Loop Ligand Gated Ion Channel Subunits and an Acetylcholine Binding Protein. PLoS One 2015; 10:e0138068. [PMID: 26368804 PMCID: PMC4569296 DOI: 10.1371/journal.pone.0138068] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 08/25/2015] [Indexed: 11/19/2022] Open
Abstract
Invertebrates possess a diverse collection of pentameric Cys-loop ligand gated ion channel (LGIC) receptors whose molecular structures, evolution and relationships to mammalian counterparts have been intensely investigated in several clinically and agriculturally important species. These receptors are targets for a variety of control agents that may also harm beneficial species. However, little is known about Cys-loop receptors in spiders, which are important natural predators of insects. We assembled de novo transcriptomes from the central and peripheral nervous systems of the Central American wandering spider Cupiennius salei, a model species for neurophysiological, behavioral and developmental studies. We found 15 Cys-loop receptor subunits that are expected to form anion or cation permeable channels, plus a putative acetylcholine binding protein (AChBP) that has only previously been reported in molluscs and one annelid. We used phylogenetic and sequence analysis to compare the spider subunits to homologous receptors in other species and predicted the 3D structures of each protein using the I-Tasser server. The quality of homology models improved with increasing sequence identity to the available high-resolution templates. We found that C. salei has orthologous γ-aminobutyric acid (GABA), GluCl, pHCl, HisCl and nAChα LGIC subunits to other arthropods, but some subgroups are specific to arachnids, or only to spiders. C. salei sequences were phylogenetically closest to gene fragments from the social spider, Stegodyphus mimosarum, indicating high conservation within the Araneomorphae suborder of spiders. C. salei sequences had similar ligand binding and transmembrane regions to other invertebrate and vertebrate LGICs. They also had motifs associated with high sensitivity to insecticides and antiparasitic agents such as fipronil, dieldrin and ivermectin. Development of truly selective control agents for pest species will require information about the molecular structure and pharmacology of Cys-loop receptors in beneficial species.
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Affiliation(s)
- Viktor Žárský
- Institute of Experimental Botany, v.v.i., Academy of Sciences of the Czech Republic, 165 02 Prague, Czech Republic and at the Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, 128 44 Prague, Czech Republic
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