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Carricaburu E, Benner O, Burlingham SR, Dos Santos Passos C, Hobaugh N, Karr CH, Chanda S. Gephyrin promotes autonomous assembly and synaptic localization of GABAergic postsynaptic components without presynaptic GABA release. Proc Natl Acad Sci U S A 2024; 121:e2315100121. [PMID: 38889143 DOI: 10.1073/pnas.2315100121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 05/17/2024] [Indexed: 06/20/2024] Open
Abstract
Synapses containing γ-aminobutyric acid (GABA) constitute the primary centers for inhibitory neurotransmission in our nervous system. It is unclear how these synaptic structures form and align their postsynaptic machineries with presynaptic terminals. Here, we monitored the cellular distribution of several GABAergic postsynaptic proteins in a purely glutamatergic neuronal culture derived from human stem cells, which virtually lacks any vesicular GABA release. We found that several GABAA receptor (GABAAR) subunits, postsynaptic scaffolds, and major cell-adhesion molecules can reliably coaggregate and colocalize at even GABA-deficient subsynaptic domains, but remain physically segregated from glutamatergic counterparts. Genetic deletions of both Gephyrin and a Gephyrin-associated guanosine di- or triphosphate (GDP/GTP) exchange factor Collybistin severely disrupted the coassembly of these postsynaptic compositions and their proper apposition with presynaptic inputs. Gephyrin-GABAAR clusters, developed in the absence of GABA transmission, could be subsequently activated and even potentiated by delayed supply of vesicular GABA. Thus, molecular organization of GABAergic postsynapses can initiate via a GABA-independent but Gephyrin-dependent intrinsic mechanism.
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Affiliation(s)
- Etta Carricaburu
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Orion Benner
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Scott R Burlingham
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | | | - Natalia Hobaugh
- Biological Sciences Division, University of Chicago, Chicago, IL 60637
| | - Charles H Karr
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
| | - Soham Chanda
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523
- Molecular, Cellular and Integrated Neurosciences Program, Colorado State University, Fort Collins, CO 80523
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO 80523
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2
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Hao Y, Liu H, Zeng XT, Wang Y, Zeng WX, Qian KY, Li L, Chi MX, Gao S, Hu Z, Tong XJ. UNC-43/CaMKII-triggered anterograde signals recruit GABA ARs to mediate inhibitory synaptic transmission and plasticity at C. elegans NMJs. Nat Commun 2023; 14:1436. [PMID: 36918518 PMCID: PMC10015018 DOI: 10.1038/s41467-023-37137-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 02/28/2023] [Indexed: 03/16/2023] Open
Abstract
Disturbed inhibitory synaptic transmission has functional impacts on neurodevelopmental and psychiatric disorders. An essential mechanism for modulating inhibitory synaptic transmission is alteration of the postsynaptic abundance of GABAARs, which are stabilized by postsynaptic scaffold proteins and recruited by presynaptic signals. However, how GABAergic neurons trigger signals to transsynaptically recruit GABAARs remains elusive. Here, we show that UNC-43/CaMKII functions at GABAergic neurons to recruit GABAARs and modulate inhibitory synaptic transmission at C. elegans neuromuscular junctions. We demonstrate that UNC-43 promotes presynaptic MADD-4B/Punctin secretion and NRX-1α/Neurexin surface delivery. Together, MADD-4B and NRX-1α recruit postsynaptic NLG-1/Neuroligin and stabilize GABAARs. Further, the excitation of GABAergic neurons potentiates the recruitment of NLG-1-stabilized-GABAARs, which depends on UNC-43, MADD-4B, and NRX-1. These data all support that UNC-43 triggers MADD-4B and NRX-1α, which act as anterograde signals to recruit postsynaptic GABAARs. Thus, our findings elucidate a mechanism for pre- and postsynaptic communication and inhibitory synaptic transmission and plasticity.
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Affiliation(s)
- Yue Hao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Haowen Liu
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Xian-Ting Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ya Wang
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Wan-Xin Zeng
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Kang-Ying Qian
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China
- University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Lei Li
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ming-Xuan Chi
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Shangbang Gao
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Zhitao Hu
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research (CJCADR), The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Xia-Jing Tong
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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3
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Feresten AH, Bhat JM, Yu AJ, Zapf R, Rankin CH, Hutter H. wrk-1 and rig-5 control pioneer and follower axon navigation in the ventral nerve cord of Caenorhabditis elegans in a nid-1 mutant background. Genetics 2023; 223:iyac187. [PMID: 36573271 PMCID: PMC9991498 DOI: 10.1093/genetics/iyac187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 12/10/2022] [Indexed: 12/28/2022] Open
Abstract
During nervous system development, neurons send out axons, which must navigate large distances to reach synaptic targets. Axons grow out sequentially. The early outgrowing axons, pioneers, must integrate information from various guidance cues in their environment to determine the correct direction of outgrowth. Later outgrowing follower axons can at least in part navigate by adhering to pioneer axons. In Caenorhabditis elegans, the right side of the largest longitudinal axon tract, the ventral nerve cord, is pioneered by the AVG axon. How the AVG axon navigates is only partially understood. In this study, we describe the role of two members of the IgCAM family, wrk-1 and rig-5, in AVG axon navigation. While wrk-1 and rig-5 single mutants do not show AVG navigation defects, both mutants have highly penetrant pioneer and follower navigation defects in a nid-1 mutant background. Both mutations increase the fraction of follower axons following the misguided pioneer axon. We found that wrk-1 and rig-5 act in different genetic pathways, suggesting that we identified two pioneer-independent guidance pathways used by follower axons. We assessed general locomotion, mechanosensory responsiveness, and habituation to determine whether axonal navigation defects impact nervous system function. In rig-5 nid-1 double mutants, we found no significant defects in free movement behavior; however, a subpopulation of animals shows minor changes in response duration habituation after mechanosensory stimulation. These results suggest that guidance defects of axons in the motor circuit do not necessarily lead to major movement or behavioral defects but impact more complex behavioral modulation.
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Affiliation(s)
- Abigail H Feresten
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
| | - Jaffar M Bhat
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
| | - Alex J Yu
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T2B5, Canada
| | - Richard Zapf
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
| | - Catharine H Rankin
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T2B5, Canada
- Department of Psychology, University of British Columbia, Vancouver, BC V6T1Z4, Canada
| | - Harald Hutter
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
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4
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Mizumoto K, Jin Y, Bessereau JL. Synaptogenesis: unmasking molecular mechanisms using Caenorhabditis elegans. Genetics 2023; 223:iyac176. [PMID: 36630525 PMCID: PMC9910414 DOI: 10.1093/genetics/iyac176] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/22/2022] [Indexed: 01/13/2023] Open
Abstract
The nematode Caenorhabditis elegans is a research model organism particularly suited to the mechanistic understanding of synapse genesis in the nervous system. Armed with powerful genetics, knowledge of complete connectomics, and modern genomics, studies using C. elegans have unveiled multiple key regulators in the formation of a functional synapse. Importantly, many signaling networks display remarkable conservation throughout animals, underscoring the contributions of C. elegans research to advance the understanding of our brain. In this chapter, we will review up-to-date information of the contribution of C. elegans to the understanding of chemical synapses, from structure to molecules and to synaptic remodeling.
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Affiliation(s)
- Kota Mizumoto
- Department of Zoology, University of British Columbia, Vancouver V6T 1Z3, Canada
| | - Yishi Jin
- Department of Neurobiology, University of California San Diego, La Jolla, CA 92093, USA
| | - Jean-Louis Bessereau
- Univ Lyon, University Claude Bernard Lyon 1, CNRS UMR 5284, INSERM U 1314, Melis, 69008 Lyon, France
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5
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Lu Y, Ahamed T, Mulcahy B, Meng J, Witvliet D, Guan SA, Holmyard D, Hung W, Wen Q, Chisholm AD, Samuel ADT, Zhen M. Extrasynaptic signaling enables an asymmetric juvenile motor circuit to produce symmetric undulation. Curr Biol 2022; 32:4631-4644.e5. [PMID: 36182701 PMCID: PMC9643663 DOI: 10.1016/j.cub.2022.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 06/17/2022] [Accepted: 09/01/2022] [Indexed: 01/28/2023]
Abstract
In many animals, there is a direct correspondence between the motor patterns that drive locomotion and the motor neuron innervation. For example, the adult C. elegans moves with symmetric and alternating dorsal-ventral bending waves arising from symmetric motor neuron input onto the dorsal and ventral muscles. In contrast to the adult, the C. elegans motor circuit at the juvenile larval stage has asymmetric wiring between motor neurons and muscles but still generates adult-like bending waves with dorsal-ventral symmetry. We show that in the juvenile circuit, wiring between excitatory and inhibitory motor neurons coordinates the contraction of dorsal muscles with relaxation of ventral muscles, producing dorsal bends. However, ventral bending is not driven by analogous wiring. Instead, ventral muscles are excited uniformly by premotor interneurons through extrasynaptic signaling. Ventral bends occur in anti-phasic entrainment to activity of the same motor neurons that drive dorsal bends. During maturation, the juvenile motor circuit is replaced by two motor subcircuits that separately drive dorsal and ventral bending. Modeling reveals that the juvenile's immature motor circuit is an adequate solution to generate adult-like dorsal-ventral bending before the animal matures. Developmental rewiring between functionally degenerate circuit solutions, which both generate symmetric bending patterns, minimizes behavioral disruption across maturation.
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Affiliation(s)
- Yangning Lu
- Department of Physiology, University of Toronto, Toronto, ON M5G 1X5, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Tosif Ahamed
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Ben Mulcahy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Jun Meng
- Department of Physiology, University of Toronto, Toronto, ON M5G 1X5, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Daniel Witvliet
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1X5, Canada
| | - Sihui Asuka Guan
- Department of Physiology, University of Toronto, Toronto, ON M5G 1X5, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Douglas Holmyard
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Wesley Hung
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Quan Wen
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA; School of Life Sciences, University of Science and Technology, Hefei, Anhui 230027, China
| | - Andrew D Chisholm
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Aravinthan D T Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Mei Zhen
- Department of Physiology, University of Toronto, Toronto, ON M5G 1X5, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5G 1X5, Canada.
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6
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Post-embryonic remodeling of the C. elegans motor circuit. Curr Biol 2022; 32:4645-4659.e3. [DOI: 10.1016/j.cub.2022.09.065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/28/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022]
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7
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Shi Y, Qin L, Wu M, Zheng J, Xie T, Shao Z. Gut neuroendocrine signaling regulates synaptic assembly in C. elegans. EMBO Rep 2022; 23:e53267. [PMID: 35748387 DOI: 10.15252/embr.202153267] [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: 05/14/2021] [Revised: 05/26/2022] [Accepted: 06/01/2022] [Indexed: 11/09/2022] Open
Abstract
Synaptic connections are essential to build a functional brain. How synapses are formed during development is a fundamental question in neuroscience. Recent studies provided evidence that the gut plays an important role in neuronal development through processing signals derived from gut microbes or nutrients. Defects in gut-brain communication can lead to various neurological disorders. Although the roles of the gut in communicating signals from its internal environment to the brain are well known, it remains unclear whether the gut plays a genetically encoded role in neuronal development. Using C. elegans as a model, we uncover that a Wnt-endocrine signaling pathway in the gut regulates synaptic development in the brain. A canonical Wnt signaling pathway promotes synapse formation through regulating the expression of the neuropeptides encoding gene nlp-40 in the gut, which functions through the neuronally expressed GPCR/AEX-2 receptor during development. Wnt-NLP-40-AEX-2 signaling likely acts to modulate neuronal activity. Our study reveals a genetic role of the gut in synaptic development and identifies a novel contribution of the gut-brain axis.
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Affiliation(s)
- Yanjun Shi
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lu Qin
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Mengting Wu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Junyu Zheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Tao Xie
- Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhiyong Shao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Department of Neurosurgery, Zhongshan Hospital, Fudan University, Shanghai, China
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8
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Differential regulation of degradation and immune pathways underlies adaptation of the ectosymbiotic nematode Laxus oneistus to oxic-anoxic interfaces. Sci Rep 2022; 12:9725. [PMID: 35697683 PMCID: PMC9192688 DOI: 10.1038/s41598-022-13235-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 05/13/2022] [Indexed: 11/09/2022] Open
Abstract
Eukaryotes may experience oxygen deprivation under both physiological and pathological conditions. Because oxygen shortage leads to a reduction in cellular energy production, all eukaryotes studied so far conserve energy by suppressing their metabolism. However, the molecular physiology of animals that naturally and repeatedly experience anoxia is underexplored. One such animal is the marine nematode Laxus oneistus. It thrives, invariably coated by its sulfur-oxidizing symbiont Candidatus Thiosymbion oneisti, in anoxic sulfidic or hypoxic sand. Here, transcriptomics and proteomics showed that, whether in anoxia or not, L. oneistus mostly expressed genes involved in ubiquitination, energy generation, oxidative stress response, immune response, development, and translation. Importantly, ubiquitination genes were also highly expressed when the nematode was subjected to anoxic sulfidic conditions, together with genes involved in autophagy, detoxification and ribosome biogenesis. We hypothesize that these degradation pathways were induced to recycle damaged cellular components (mitochondria) and misfolded proteins into nutrients. Remarkably, when L. oneistus was subjected to anoxic sulfidic conditions, lectin and mucin genes were also upregulated, potentially to promote the attachment of its thiotrophic symbiont. Furthermore, the nematode appeared to survive oxygen deprivation by using an alternative electron carrier (rhodoquinone) and acceptor (fumarate), to rewire the electron transfer chain. On the other hand, under hypoxia, genes involved in costly processes (e.g., amino acid biosynthesis, development, feeding, mating) were upregulated, together with the worm's Toll-like innate immunity pathway and several immune effectors (e.g., bactericidal/permeability-increasing proteins, fungicides). In conclusion, we hypothesize that, in anoxic sulfidic sand, L. oneistus upregulates degradation processes, rewires the oxidative phosphorylation and reinforces its coat of bacterial sulfur-oxidizers. In upper sand layers, instead, it appears to produce broad-range antimicrobials and to exploit oxygen for biosynthesis and development.
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9
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Choudhary S, Kashyap SS, Martin RJ, Robertson AP. Advances in our understanding of nematode ion channels as potential anthelmintic targets. Int J Parasitol Drugs Drug Resist 2022; 18:52-86. [PMID: 35149380 PMCID: PMC8841521 DOI: 10.1016/j.ijpddr.2021.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 12/15/2022]
Abstract
Ion channels are specialized multimeric proteins that underlie cell excitability. These channels integrate with a variety of neuromuscular and biological functions. In nematodes, the physiological behaviors including locomotion, navigation, feeding and reproduction, are regulated by these protein entities. Majority of the antinematodal chemotherapeutics target the ion channels to disrupt essential biological functions. Here, we have summarized current advances in our understanding of nematode ion channel pharmacology. We review cys-loop ligand gated ion channels (LGICs), including nicotinic acetylcholine receptors (nAChRs), acetylcholine-chloride gated ion channels (ACCs), glutamate-gated chloride channels (GluCls), and GABA (γ-aminobutyric acid) receptors, and other ionotropic receptors (transient receptor potential (TRP) channels and potassium ion channels). We have provided an update on the pharmacological properties of these channels from various nematodes. This article catalogs the differences in ion channel composition and resulting pharmacology in the phylum Nematoda. This diversity in ion channel subunit repertoire and pharmacology emphasizes the importance of pursuing species-specific drug target research. In this review, we have provided an overview of recent advances in techniques and functional assays available for screening ion channel properties and their application.
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Affiliation(s)
- Shivani Choudhary
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Sudhanva S Kashyap
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Richard J Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
| | - Alan P Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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10
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Politi FAS, Bueno RV, Zeoly LA, Fantatto RR, Eloy JDO, Chorilli M, Coelho F, Guido RVC, Chagas ACDS, Furlan M. Anthelmintic activity of a nanoformulation based on thiophenes identified in Tagetes patula L. (Asteraceae) against the small ruminant nematode Haemonchus contortus. Acta Trop 2021; 219:105920. [PMID: 33861973 DOI: 10.1016/j.actatropica.2021.105920] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 02/02/2021] [Accepted: 04/07/2021] [Indexed: 11/25/2022]
Abstract
The synthesis of thiophenic compounds, previously identified in Tagetes patula, revealed that 4-(5'-(hydroxymethyl)-[2,2'-bithiophene]-5-yl)but-3-yn-1-ol), or simply Thio1, has a pronounced in vitro anthelmintic effect against Haemonchus contortus, showing 100% efficacy in the egg hatch and larval development tests presenting EC50 = 0.1731 mg.mL-1 and EC50 = 0.3243 mg.mL-1, respectively. So, this compound was selected to preparation of a nanostructured formulation to be orally administered to Santa Inês sheep. In general, from the fecal egg count reduction test (FECRT), it was observed that the product kept the parasitic load in the digestive tract of the hosts stable, with eggs per gram of faeces (EPG) counts having a mean value < 3,000 (EPGmean = 2167.1, efficacy = 36,45%), thus protecting the animals from health risks caused by a massive nematode infestation. To better understand the mode of action of this thiophene derivative, in silico molecular modeling studies were carried out with the glutamate-activated chloride channel (GluCl), a well-known molecular target of anthelmintic compounds. Based on the affinity score (GlideScore = -5.7 kcal.mol-1) and the proposed binding mode, Thio1 could be classified as a potential GluCl ligand, justifying the promising results observed in the anthelmintic assays.
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11
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Wang M, Witvliet D, Wu M, Kang L, Shao Z. Temperature regulates synaptic subcellular specificity mediated by inhibitory glutamate signaling. PLoS Genet 2021; 17:e1009295. [PMID: 33428618 PMCID: PMC7822552 DOI: 10.1371/journal.pgen.1009295] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 01/22/2021] [Accepted: 12/05/2020] [Indexed: 01/13/2023] Open
Abstract
Environmental factors such as temperature affect neuronal activity and development. However, it remains unknown whether and how they affect synaptic subcellular specificity. Here, using the nematode Caenorhabditis elegans AIY interneurons as a model, we found that high cultivation temperature robustly induces defects in synaptic subcellular specificity through glutamatergic neurotransmission. Furthermore, we determined that the functional glutamate is mainly released by the ASH sensory neurons and sensed by two conserved inhibitory glutamate-gated chloride channels GLC-3 and GLC-4 in AIY. Our work not only presents a novel neurotransmission-dependent mechanism underlying the synaptic subcellular specificity, but also provides a potential mechanistic insight into high-temperature-induced neurological defects.
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Affiliation(s)
- Mengqing Wang
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Daniel Witvliet
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Mengting Wu
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lijun Kang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Zhiyong Shao
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
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12
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The netrin receptor UNC-40/DCC assembles a postsynaptic scaffold and sets the synaptic content of GABA A receptors. Nat Commun 2020; 11:2674. [PMID: 32471987 PMCID: PMC7260190 DOI: 10.1038/s41467-020-16473-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 04/28/2020] [Indexed: 01/11/2023] Open
Abstract
Increasing evidence indicates that guidance molecules used during development for cellular and axonal navigation also play roles in synapse maturation and homeostasis. In C. elegans the netrin receptor UNC-40/DCC controls the growth of dendritic-like muscle cell extensions towards motoneurons and is required to recruit type A GABA receptors (GABAARs) at inhibitory neuromuscular junctions. Here we show that activation of UNC-40 assembles an intracellular synaptic scaffold by physically interacting with FRM-3, a FERM protein orthologous to FARP1/2. FRM-3 then recruits LIN-2, the ortholog of CASK, that binds the synaptic adhesion molecule NLG-1/Neuroligin and physically connects GABAARs to prepositioned NLG-1 clusters. These processes are orchestrated by the synaptic organizer CePunctin/MADD-4, which controls the localization of GABAARs by positioning NLG-1/neuroligin at synapses and regulates the synaptic content of GABAARs through the UNC-40-dependent intracellular scaffold. Since DCC is detected at GABA synapses in mammals, DCC might also tune inhibitory neurotransmission in the mammalian brain. The netrin receptor UNC-40/DCC is required to recruit GABAAR at neuromuscular junctions in C. elegans. Here, the authors show that UNC-40/DCC assembles an intracellular synaptic scaffold, regulating the content of GABAAR and inhibitory neurotransmission.
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13
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The Synaptic Autophagy Cycle. J Mol Biol 2019; 432:2589-2604. [PMID: 31866297 DOI: 10.1016/j.jmb.2019.12.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/10/2019] [Accepted: 12/12/2019] [Indexed: 02/08/2023]
Abstract
Macroautophagy (hereafter referred to as autophagy) is an evolutionarily conserved pathway in which proteins and organelles are delivered to the lysosome for degradation. In neurons, autophagy was originally described as associated with disease states and neuronal survival. Over the last decade, however, evidence has accumulated that autophagy controls synaptic function in both the axon and dendrite. Here, we review this literature, highlighting the role of autophagy in the pre- and postsynapse, synaptic plasticity, and behavior. We end by discussing open questions in the field of synaptic autophagy.
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Zhou X, Bessereau JL. Molecular Architecture of Genetically-Tractable GABA Synapses in C. elegans. Front Mol Neurosci 2019; 12:304. [PMID: 31920535 PMCID: PMC6920096 DOI: 10.3389/fnmol.2019.00304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/26/2019] [Indexed: 12/18/2022] Open
Abstract
Inhibitory synapses represent a minority of the total chemical synapses in the mammalian brain, yet proper tuning of inhibition is fundamental to shape neuronal network properties. The neurotransmitter γ-aminobutyric acid (GABA) mediates rapid synaptic inhibition by the activation of the type A GABA receptor (GABAAR), a pentameric chloride channel that governs major inhibitory neuronal transduction in the nervous system. Impaired GABA transmission leads to a variety of neuropsychiatric diseases, including schizophrenia, autism, epilepsy or anxiety. From an evolutionary perspective, GABAAR shows remarkable conservations, and are found in all eukaryotic clades and even in bacteria and archaea. Specifically, bona fide GABAARs are found in the nematode Caenorhabditis elegans. Because of the anatomical simplicity of the nervous system and its amenability to genetic manipulations, C. elegans provide a powerful system to investigate the molecular and cellular biology of GABA synapses. In this mini review article, we will introduce the structure of the C. elegans GABAergic system and describe recent advances that have identified novel proteins controlling the localization of GABAARs at synapses. In particular, Ce-Punctin/MADD-4 is an evolutionarily-conserved extracellular matrix protein that behaves as an anterograde synaptic organizer to instruct the excitatory or inhibitory identity of postsynaptic domains.
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Affiliation(s)
- Xin Zhou
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Jean-Louis Bessereau
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
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15
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Rothman J, Jarriault S. Developmental Plasticity and Cellular Reprogramming in Caenorhabditis elegans. Genetics 2019; 213:723-757. [PMID: 31685551 PMCID: PMC6827377 DOI: 10.1534/genetics.119.302333] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/25/2019] [Indexed: 12/28/2022] Open
Abstract
While Caenorhabditis elegans was originally regarded as a model for investigating determinate developmental programs, landmark studies have subsequently shown that the largely invariant pattern of development in the animal does not reflect irreversibility in rigidly fixed cell fates. Rather, cells at all stages of development, in both the soma and germline, have been shown to be capable of changing their fates through mutation or forced expression of fate-determining factors, as well as during the normal course of development. In this chapter, we review the basis for natural and induced cellular plasticity in C. elegans We describe the events that progressively restrict cellular differentiation during embryogenesis, starting with the multipotency-to-commitment transition (MCT) and subsequently through postembryonic development of the animal, and consider the range of molecular processes, including transcriptional and translational control systems, that contribute to cellular plasticity. These findings in the worm are discussed in the context of both classical and recent studies of cellular plasticity in vertebrate systems.
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Affiliation(s)
- Joel Rothman
- Department of MCD Biology and Neuroscience Research Institute, University of California, Santa Barbara, California 93111, and
| | - Sophie Jarriault
- IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Department of Development and Stem Cells, CNRS UMR7104, Inserm U1258, Université de Strasbourg, 67404 Illkirch CU Strasbourg, France
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16
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Huang YC, Pirri JK, Rayes D, Gao S, Mulcahy B, Grant J, Saheki Y, Francis MM, Zhen M, Alkema MJ. Gain-of-function mutations in the UNC-2/CaV2α channel lead to excitation-dominant synaptic transmission in Caenorhabditis elegans. eLife 2019; 8:e45905. [PMID: 31364988 PMCID: PMC6713474 DOI: 10.7554/elife.45905] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 07/30/2019] [Indexed: 01/17/2023] Open
Abstract
Mutations in pre-synaptic voltage-gated calcium channels can lead to familial hemiplegic migraine type 1 (FHM1). While mammalian studies indicate that the migraine brain is hyperexcitable due to enhanced excitation or reduced inhibition, the molecular and cellular mechanisms underlying this excitatory/inhibitory (E/I) imbalance are poorly understood. We identified a gain-of-function (gf) mutation in the Caenorhabditis elegans CaV2 channel α1 subunit, UNC-2, which leads to increased calcium currents. unc-2(zf35gf) mutants exhibit hyperactivity and seizure-like motor behaviors. Expression of the unc-2 gene with FHM1 substitutions R192Q and S218L leads to hyperactivity similar to that of unc-2(zf35gf) mutants. unc-2(zf35gf) mutants display increased cholinergic and decreased GABAergic transmission. Moreover, increased cholinergic transmission in unc-2(zf35gf) mutants leads to an increase of cholinergic synapses and a TAX-6/calcineurin-dependent reduction of GABA synapses. Our studies reveal mechanisms through which CaV2 gain-of-function mutations disrupt excitation-inhibition balance in the nervous system.
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Affiliation(s)
- Yung-Chi Huang
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Jennifer K Pirri
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Diego Rayes
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Shangbang Gao
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Ben Mulcahy
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Jeff Grant
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Yasunori Saheki
- Lulu and Anthony Wang Laboratory of Neural Circuits and BehaviorThe Rockefeller UniversityNew YorkUnited States
| | - Michael M Francis
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
- Department of PhysiologyUniversity of TorontoTorontoCanada
| | - Mark J Alkema
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
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D'Alessandro M, Richard M, Stigloher C, Gache V, Boulin T, Richmond JE, Bessereau JL. CRELD1 is an evolutionarily-conserved maturational enhancer of ionotropic acetylcholine receptors. eLife 2018; 7:39649. [PMID: 30407909 PMCID: PMC6245729 DOI: 10.7554/elife.39649] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/05/2018] [Indexed: 12/22/2022] Open
Abstract
The assembly of neurotransmitter receptors in the endoplasmic reticulum limits the number of receptors delivered to the plasma membrane, ultimately controlling neurotransmitter sensitivity and synaptic transfer function. In a forward genetic screen conducted in the nematode C. elegans, we identified crld-1 as a gene required for the synaptic expression of ionotropic acetylcholine receptors (AChR). We demonstrated that the CRLD-1A isoform is a membrane-associated ER-resident protein disulfide isomerase (PDI). It physically interacts with AChRs and promotes the assembly of AChR subunits in the ER. Mutations of Creld1, the human ortholog of crld-1a, are responsible for developmental cardiac defects. We showed that Creld1 knockdown in mouse muscle cells decreased surface expression of AChRs and that expression of mouse Creld1 in C. elegans rescued crld-1a mutant phenotypes. Altogether these results identify a novel and evolutionarily-conserved maturational enhancer of AChR biogenesis, which controls the abundance of functional receptors at the cell surface.
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Affiliation(s)
- Manuela D'Alessandro
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Magali Richard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Christian Stigloher
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Vincent Gache
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Thomas Boulin
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, United States
| | - Jean-Louis Bessereau
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
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18
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Regulation and Roles of Autophagy at Synapses. Trends Cell Biol 2018; 28:646-661. [DOI: 10.1016/j.tcb.2018.03.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 03/12/2018] [Accepted: 03/30/2018] [Indexed: 12/21/2022]
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19
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Jin Y, Qi YB. Building stereotypic connectivity: mechanistic insights into structural plasticity from C. elegans. Curr Opin Neurobiol 2017; 48:97-105. [PMID: 29182952 DOI: 10.1016/j.conb.2017.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 11/07/2017] [Accepted: 11/14/2017] [Indexed: 01/10/2023]
Abstract
The ability of neurons to modify or remodel their synaptic connectivity is critical for the function of neural circuitry throughout the life of an animal. Understanding the mechanisms underlying neuronal structural changes is central to our knowledge of how the nervous system is shaped for complex behaviors and how it further adapts to developmental and environmental demands. Caenorhabditis elegans provides a powerful model for examining developmental processes and for discovering mechanisms controlling neural plasticity. Recent findings have identified conserved themes underlying neural plasticity in development and under environmental stress.
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Affiliation(s)
- Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Yingchuan B Qi
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
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20
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Barbagallo B, Philbrook A, Touroutine D, Banerjee N, Oliver D, Lambert CM, Francis MM. Excitatory neurons sculpt GABAergic neuronal connectivity in the C. elegans motor circuit. Development 2017; 144:1807-1819. [PMID: 28420711 DOI: 10.1242/dev.141911] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 04/03/2017] [Indexed: 11/20/2022]
Abstract
Establishing and maintaining the appropriate number of GABA synapses is key for balancing excitation and inhibition in the nervous system, though we have only a limited understanding of the mechanisms controlling GABA circuit connectivity. Here, we show that disrupting cholinergic innervation of GABAergic neurons in the C. elegans motor circuit alters GABAergic neuron synaptic connectivity. These changes are accompanied by reduced frequency and increased amplitude of GABAergic synaptic events. Acute genetic disruption in early development, during the integration of post-embryonic-born GABAergic neurons into the circuit, produces irreversible effects on GABAergic synaptic connectivity that mimic those produced by chronic manipulations. In contrast, acute genetic disruption of cholinergic signaling in the adult circuit does not reproduce these effects. Our findings reveal that GABAergic signaling is regulated by cholinergic neuronal activity, probably through distinct mechanisms in the developing and mature nervous system.
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Affiliation(s)
- Belinda Barbagallo
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Alison Philbrook
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Denis Touroutine
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Navonil Banerjee
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Devyn Oliver
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Christopher M Lambert
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Michael M Francis
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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21
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Camargo G, Elizalde A, Trujillo X, Montoya-Pérez R, Mendoza-Magaña ML, Hernandez-Chavez A, Hernandez L. Inactivation of GABAA receptor is related to heat shock stress response in organism model Caenorhabditis elegans. Cell Stress Chaperones 2016; 21:763-72. [PMID: 27230213 PMCID: PMC5003793 DOI: 10.1007/s12192-016-0701-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 04/29/2016] [Accepted: 05/11/2016] [Indexed: 01/08/2023] Open
Abstract
The mechanisms underlying oxidative stress (OS) resistance are not completely clear. Caenorhabditis elegans (C. elegans) is a good organism model to study OS because it displays stress responses similar to those in mammals. Among these mechanisms, the insulin/IGF-1 signaling (IIS) pathway is thought to affect GABAergic neurotransmission. The aim of this study was to determine the influence of heat shock stress (HS) on GABAergic activity in C. elegans. For this purpose, we tested the effect of exposure to picrotoxin (PTX), gamma-aminobutyric acid (GABA), hydrogen peroxide, and HS on the occurrence of a shrinking response (SR) after nose touch stimulus in N2 (WT) worms. Moreover, the effect of HS on the expression of UNC-49 (GABAA receptor ortholog) in the EG1653 strain and the effect of GABA and PTX exposure on HSP-16.2 expression in the TJ375 strain were analyzed. PTX 1 mM- or H2O2 0.7 mM-exposed worms displayed a SR in about 80 % of trials. GABA exposure did not cause a SR. HS prompted the occurrence of a SR as did PTX 1 mM or H2O2 0.7 mM exposure. In addition, HS increased UNC-49 expression, and PTX augmented HSP-16.2 expression. Thus, the results of the present study suggest that oxidative stress, through either H2O2 exposure or application of heat shock, inactivates the GABAergic system, which subsequently would affect the oxidative stress response, perhaps by enhancing the activity of transcription factors DAF-16 and HSF-1, both regulated by the IIS pathway and related to hsp-16.2 expression.
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Affiliation(s)
- Gabriela Camargo
- Laboratorio de Neurofisiología, Departamento de Fisiología, Centro Universitario de Ciencias dela Salud, Universidad de Guadalajara, Sierra Mojada # 950, Guadalajara, 44340, Jalisco, Mexico
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Av. 25 de Julio # 965, Colima, 28045, Colima, Mexico
- Laboratorio de Biotecnología, Departamento de Botánica y Zoología, Centro Universitariode Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ramón Padilla Sánchez # 2100, Zapopan, 45110, Jalisco, Mexico
| | - Alejandro Elizalde
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Av. 25 de Julio # 965, Colima, 28045, Colima, Mexico
| | - Xochitl Trujillo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Av. 25 de Julio # 965, Colima, 28045, Colima, Mexico
| | - Rocío Montoya-Pérez
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Francisco J. Mújica S/N, Morelia, 58030, Michoacán, Mexico
| | - María Luisa Mendoza-Magaña
- Laboratorio de Neurofisiología, Departamento de Fisiología, Centro Universitario de Ciencias dela Salud, Universidad de Guadalajara, Sierra Mojada # 950, Guadalajara, 44340, Jalisco, Mexico
| | - Abel Hernandez-Chavez
- Departamento de Fisiología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, SierraMojada # 950, Guadalajara, 44340, Jalisco, Mexico
| | - Leonardo Hernandez
- Laboratorio de Neurofisiología, Departamento de Fisiología, Centro Universitario de Ciencias dela Salud, Universidad de Guadalajara, Sierra Mojada # 950, Guadalajara, 44340, Jalisco, Mexico.
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22
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Kurup N, Jin Y. Neural circuit rewiring: insights from DD synapse remodeling. WORM 2015; 5:e1129486. [PMID: 27073734 DOI: 10.1080/21624054.2015.1129486] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 11/24/2015] [Accepted: 12/04/2015] [Indexed: 01/27/2023]
Abstract
Nervous systems exhibit many forms of neuronal plasticity during growth, learning and memory consolidation, as well as in response to injury. Such plasticity can occur across entire nervous systems as with the case of insect metamorphosis, in individual classes of neurons, or even at the level of a single neuron. A striking example of neuronal plasticity in C. elegans is the synaptic rewiring of the GABAergic Dorsal D-type motor neurons during larval development, termed DD remodeling. DD remodeling entails multi-step coordination to concurrently eliminate pre-existing synapses and form new synapses on different neurites, without changing the overall morphology of the neuron. This mini-review focuses on recent advances in understanding the cellular and molecular mechanisms driving DD remodeling.
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Affiliation(s)
- Naina Kurup
- Neurobiology Section, Division of Biological Sciences, University of California , San Diego, La Jolla, CA, USA
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA; Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA, USA
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23
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Pirri JK, Rayes D, Alkema MJ. A Change in the Ion Selectivity of Ligand-Gated Ion Channels Provides a Mechanism to Switch Behavior. PLoS Biol 2015; 13:e1002238. [PMID: 26348462 PMCID: PMC4562599 DOI: 10.1371/journal.pbio.1002238] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 07/30/2015] [Indexed: 11/19/2022] Open
Abstract
Behavioral output of neural networks depends on a delicate balance between excitatory and inhibitory synaptic connections. However, it is not known whether network formation and stability is constrained by the sign of synaptic connections between neurons within the network. Here we show that switching the sign of a synapse within a neural circuit can reverse the behavioral output. The inhibitory tyramine-gated chloride channel, LGC-55, induces head relaxation and inhibits forward locomotion during the Caenorhabditis elegans escape response. We switched the ion selectivity of an inhibitory LGC-55 anion channel to an excitatory LGC-55 cation channel. The engineered cation channel is properly trafficked in the native neural circuit and results in behavioral responses that are opposite to those produced by activation of the LGC-55 anion channel. Our findings indicate that switches in ion selectivity of ligand-gated ion channels (LGICs) do not affect network connectivity or stability and may provide an evolutionary and a synthetic mechanism to change behavior. A study in Caenorhabditis elegans shows that switching the sign of a synapse within a neural circuit can reverse the behavioral output, providing an evolutionary and synthetic mechanism for changing behavior. Fast neurotransmission in the nervous system is mediated by ligand-gated ion channels. Within the nervous system, the sign of synaptic connections, i.e., whether they are excitatory or inhibitory, is determined by the charge of the ions that flow through these channels. In general, channels that conduct positive ions are excitatory, whereas channels that conduct negative ions are inhibitory. Here, we investigate if it is possible to flip the behavioral output of a neural circuit by changing the sign of a synapse within that circuit. The neural circuit we study controls the escape response of the nematode Caenorhabditis elegans. Activation of the inhibitory receptor, the tyramine-gated chloride channel LGC-55, coordinates the suppression of head movements and backward locomotion during the C. elegans escape response. We selectively mutated LGC-55 to transform it from an inhibitory into an excitatory ion channel and generated transgenic worms in which the inhibitory channel is replaced by the excitatory version of LGC-55. We show that the excitatory version of LGC-55 is properly localized to the postsynaptic compartments, is activated by the natural ligand, and does not affect network connectivity or stability. However, its expression leads to behavioral responses that are opposite to those produced by activation of the native inhibitory channel. We propose that switching the sign of a synapse not only provides a synthetic mechanism to flip behavioral output but could also be an evolutionary mechanism to change behavior.
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Affiliation(s)
- Jennifer K. Pirri
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Diego Rayes
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, UNS-CONICET, Bahía Blanca, Argentina
| | - Mark J. Alkema
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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24
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Howell K, White JG, Hobert O. Spatiotemporal control of a novel synaptic organizer molecule. Nature 2015; 523:83-7. [PMID: 26083757 PMCID: PMC9134992 DOI: 10.1038/nature14545] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 05/12/2015] [Indexed: 12/13/2022]
Abstract
Synapse formation is a process tightly controlled in space and time. How gene regulatory mechanisms specify spatial and temporal aspects of synapse formation is not well understood. In the nematode C.elegans, two subtypes of the D-type inhibitory motor neuron (MN) classes, the dorsal D (DD) and ventral D (VD) neurons, extend axons along both the dorsal and ventral nerve cords 1. The embryonically generated DD MNs initially innervate ventral muscles in the first (L1) larval stage and receive their synaptic input from cholinergic MNs in the dorsal cord. They rewire by the end of the L1 molt to innervate dorsal muscles and to be innervated by newly formed ventral cholinergic MNs 1. VD MNs develop after the L1 molt; they take over the innervation of ventral muscles and receive their synaptic input from dorsal cholinergic MNs. We show here that the spatiotemporal control of synaptic wiring of the D-type neurons is controlled by an intersectional transcriptional strategy in which the UNC-30 Pitx-type homeodomain transcription factor acts together in embryonic and early larval stages with the temporally controlled LIN-14 transcription factor to prevent premature synapse rewiring of the DD MNs and, together with the UNC-55 nuclear hormone receptor, to prevent aberrant VD synaptic wiring in later larval and adult stages. A key effector of this intersectional transcription factor combination is a novel synaptic organizer molecule, the single immunoglobulin domain protein OIG-1. OIG-1 is perisynaptically localized along the synaptic outputs of the D-type MNs in a temporally controlled manner and is required for appropriate selection of both pre- and post-synaptic partners.
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25
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C. elegans Punctin Clusters GABAA Receptors via Neuroligin Binding and UNC-40/DCC Recruitment. Neuron 2015; 86:1407-19. [DOI: 10.1016/j.neuron.2015.05.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 02/13/2015] [Accepted: 03/27/2015] [Indexed: 12/21/2022]
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26
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Maro GS, Gao S, Olechwier AM, Hung WL, Liu M, Özkan E, Zhen M, Shen K. MADD-4/Punctin and Neurexin Organize C. elegans GABAergic Postsynapses through Neuroligin. Neuron 2015; 86:1420-32. [PMID: 26028574 DOI: 10.1016/j.neuron.2015.05.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 04/07/2015] [Accepted: 05/01/2015] [Indexed: 11/29/2022]
Abstract
At synapses, the presynaptic release machinery is precisely juxtaposed to the postsynaptic neurotransmitter receptors. We studied the molecular mechanisms underlying this exquisite alignment at the C. elegans inhibitory synapses. We found that the sole C. elegans neuroligin homolog, NLG-1, localizes specifically at GABAergic postsynapses and is required for clustering the GABA(A) receptor UNC-49. Two presynaptic factors, Punctin/MADD-4, an ADAMTS-like extracellular protein, and neurexin/NRX-1, act partially redundantly to recruit NLG-1 to synapses. In the absence of both MADD-4 and NRX-1, NLG-1 and GABA(A) receptors fail to cluster, and GABAergic synaptic transmission is severely compromised. Biochemically, we detect an interaction between MADD-4 and NLG-1, as well as between MADD-4 and NRX-1. Interestingly, the presence of NRX-1 potentiates binding between Punctin/MADD-4 and NLG-1, suggestive of a tripartite receptor ligand complex. We propose that presynaptic terminals induce postsynaptic receptor clustering through the action of both secreted ECM proteins and trans-synaptic adhesion complexes.
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Affiliation(s)
- Géraldine S Maro
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Shangbang Gao
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G1X5, Canada
| | - Agnieszka M Olechwier
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Wesley L Hung
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G1X5, Canada
| | - Michael Liu
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Engin Özkan
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G1X5, Canada.
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA.
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27
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Han B, Bellemer A, Koelle MR. An evolutionarily conserved switch in response to GABA affects development and behavior of the locomotor circuit of Caenorhabditis elegans. Genetics 2015; 199:1159-72. [PMID: 25644702 PMCID: PMC4391577 DOI: 10.1534/genetics.114.173963] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 01/28/2015] [Indexed: 01/23/2023] Open
Abstract
The neurotransmitter gamma-aminobutyric acid (GABA) is depolarizing in the developing vertebrate brain, but in older animals switches to hyperpolarizing and becomes the major inhibitory neurotransmitter in adults. We discovered a similar developmental switch in GABA response in Caenorhabditis elegans and have genetically analyzed its mechanism and function in a well-defined circuit. Worm GABA neurons innervate body wall muscles to control locomotion. Activation of GABAA receptors with their agonist muscimol in newly hatched first larval (L1) stage animals excites muscle contraction and thus is depolarizing. At the mid-L1 stage, as the GABAergic neurons rewire onto their mature muscle targets, muscimol shifts to relaxing muscles and thus has switched to hyperpolarizing. This muscimol response switch depends on chloride transporters in the muscles analogous to those that control GABA response in mammalian neurons: the chloride accumulator sodium-potassium-chloride-cotransporter-1 (NKCC-1) is required for the early depolarizing muscimol response, while the two chloride extruders potassium-chloride-cotransporter-2 (KCC-2) and anion-bicarbonate-transporter-1 (ABTS-1) are required for the later hyperpolarizing response. Using mutations that disrupt GABA signaling, we found that neural circuit development still proceeds to completion but with an ∼6-hr delay. Using optogenetic activation of GABAergic neurons, we found that endogenous GABAA signaling in early L1 animals, although presumably depolarizing, does not cause an excitatory response. Thus a developmental depolarizing-to-hyperpolarizing shift is an ancient conserved feature of GABA signaling, but existing theories for why this shift occurs appear inadequate to explain its function upon rigorous genetic analysis of a well-defined neural circuit.
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Affiliation(s)
- Bingjie Han
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520
| | - Andrew Bellemer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520
| | - Michael R Koelle
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520
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Cherra SJ, Jin Y. Advances in synapse formation: forging connections in the worm. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2015; 4:85-97. [PMID: 25472860 PMCID: PMC4339659 DOI: 10.1002/wdev.165] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 10/09/2014] [Accepted: 10/24/2014] [Indexed: 12/27/2022]
Abstract
UNLABELLED Synapse formation is the quintessential process by which neurons form specific connections with their targets to enable the development of functional circuits. Over the past few decades, intense research efforts have identified thousands of proteins that localize to the pre- and postsynaptic compartments. Genetic dissection has provided important insights into the nexus of the molecular and cellular network, and has greatly advanced our knowledge about how synapses form and function physiologically. Moreover, recent studies have highlighted the complex regulation of synapse formation with the identification of novel mechanisms involving cell interactions from non-neuronal sources. In this review, we cover the conserved pathways required for synaptogenesis and place specific focus on new themes of synapse modulation arising from studies in Caenorhabditis elegans. For further resources related to this article, please visit the WIREs website. CONFLICT OF INTEREST The authors have declared no conflicts of interest for this article.
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Affiliation(s)
- Salvatore J. Cherra
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego
- Howard Hughes Medical Institute
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In vivo single-molecule imaging identifies altered dynamics of calcium channels in dystrophin-mutant C. elegans. Nat Commun 2014; 5:4974. [PMID: 25232639 PMCID: PMC4199201 DOI: 10.1038/ncomms5974] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/12/2014] [Indexed: 01/15/2023] Open
Abstract
Single-molecule (SM) fluorescence microscopy allows the imaging of biomolecules in cultured cells with a precision of a few nanometres but has yet to be implemented in living adult animals. Here we used split-GFP (green fluorescent protein) fusions and complementation-activated light microscopy (CALM) for subresolution imaging of individual membrane proteins in live Caenorhabditis elegans (C. elegans). In vivo tissue-specific SM tracking of transmembrane CD4 and voltage-dependent Ca2+ channels (VDCC) was achieved with a precision of 30 nm within neuromuscular synapses and at the surface of muscle cells in normal and dystrophin-mutant worms. Through diffusion analyses, we reveal that dystrophin is involved in modulating the confinement of VDCC within sarcolemmal membrane nanodomains in response to varying tonus of C. elegans body-wall muscles. CALM expands the applications of SM imaging techniques beyond the petri dish and opens the possibility to explore the molecular basis of homeostatic and pathological cellular processes with subresolution precision, directly in live animals. Single molecule fluorescence microscopy is a powerful technique to study protein dynamics in cells, but it has not been applied to adult animals. The authors use complementation-activated light microscopy in C. elegansto discover that dystrophin regulates the diffusion properties of voltage-dependent calcium ion channels at the surface of body-wall muscle cells.![]()
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Pinan-Lucarré B, Tu H, Pierron M, Cruceyra PI, Zhan H, Stigloher C, Richmond JE, Bessereau JL. C. elegans Punctin specifies cholinergic versus GABAergic identity of postsynaptic domains. Nature 2014; 511:466-70. [DOI: 10.1038/nature13313] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 04/07/2014] [Indexed: 11/09/2022]
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Hernando G, Bouzat C. Caenorhabditis elegans neuromuscular junction: GABA receptors and ivermectin action. PLoS One 2014; 9:e95072. [PMID: 24743647 PMCID: PMC3990606 DOI: 10.1371/journal.pone.0095072] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/23/2014] [Indexed: 11/25/2022] Open
Abstract
The prevalence of human and animal helminth infections remains staggeringly high, thus urging the need for concerted efforts towards this area of research. GABA receptors, encoded by the unc-49 gene, mediate body muscle inhibition in Caenorhabditis elegans and parasitic nematodes and are targets of anthelmintic drugs. Thus, the characterization of nematode GABA receptors provides a foundation for rational anti-parasitic drug design. We therefore explored UNC-49 channels from C. elegans muscle cultured cells of the first larval stage at the electrophysiological and behavioral levels. Whole-cell recordings reveal that GABA, muscimol and the anthelmintic piperazine elicit macroscopic currents from UNC-49 receptors that decay in their sustained presence, indicating full desensitization. Single-channel recordings show that all drugs elicit openings of ∼2.5 pA (+100 mV), which appear either as brief isolated events or in short bursts. The comparison of the lowest concentration required for detectable channel opening, the frequency of openings and the amplitude of macroscopic currents suggest that piperazine is the least efficacious of the three drugs. Macroscopic and single-channel GABA-activated currents are profoundly and apparently irreversibly inhibited by ivermectin. To gain further insight into ivermectin action at C. elegans muscle, we analyzed its effect on single-channel activity of the levamisol-sensitive nicotinic receptor (L-AChR), the excitatory receptor involved in neuromuscular transmission. Ivermectin produces a profound inhibition of the frequency of channel opening without significant changes in channel properties. By revealing that ivermectin inhibits C. elegans muscle GABA and L-AChR receptors, our study adds two receptors to the already known ivermectin targets, thus contributing to the elucidation of its pleiotropic effects. Behavioral assays in worms show that ivermectin potentiates piperazine-induced paralysis, thus suggesting that their combination is a good strategy to overcome the increasing resistance of parasites, an issue of global concern for human and animal health.
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Affiliation(s)
- Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca-Universidad Nacional del Sur, Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Buenos Aires, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca-Universidad Nacional del Sur, Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Buenos Aires, Argentina
- * E-mail:
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Wu YE, Huo L, Maeder CI, Feng W, Shen K. The balance between capture and dissociation of presynaptic proteins controls the spatial distribution of synapses. Neuron 2013; 78:994-1011. [PMID: 23727120 DOI: 10.1016/j.neuron.2013.04.035] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2013] [Indexed: 11/19/2022]
Abstract
The location, size, and number of synapses critically influence the specificity and strength of neural connections. In axons, synaptic vesicle (SV) and active zone (AZ) proteins are transported by molecular motors and accumulate at discrete presynaptic loci. Little is known about the mechanisms coordinating presynaptic protein transport and deposition to achieve proper distribution of synaptic material. Here we show that SV and AZ proteins exhibit extensive cotransport and undergo frequent pauses. At the axonal and synaptic pause sites, the balance between the capture and dissociation of mobile transport packets determines the extent of presynaptic assembly. The small G protein ARL-8 inhibits assembly by promoting dissociation, while a JNK kinase pathway and AZ assembly proteins inhibit dissociation. Furthermore, ARL-8 directly binds to the UNC-104/KIF1A motor to limit the capture efficiency. Together, molecular regulation of the dichotomy between axonal trafficking and local assembly controls vital aspects of synapse formation and maintenance.
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Affiliation(s)
- Ye E Wu
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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Caylor RC, Jin Y, Ackley BD. The Caenorhabditis elegans voltage-gated calcium channel subunits UNC-2 and UNC-36 and the calcium-dependent kinase UNC-43/CaMKII regulate neuromuscular junction morphology. Neural Dev 2013; 8:10. [PMID: 23663262 PMCID: PMC3661369 DOI: 10.1186/1749-8104-8-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/25/2013] [Indexed: 11/30/2022] Open
Abstract
Background The conserved Caenorhabditis elegans proteins NID-1/nidogen and PTP-3A/LAR-RPTP function to efficiently localize the presynaptic scaffold protein SYD-2/α-liprin at active zones. Loss of function in these molecules results in defects in the size, morphology and spacing of neuromuscular junctions. Results Here we show that the Cav2-like voltage-gated calcium channel (VGCC) proteins, UNC-2 and UNC-36, and the calmodulin kinase II (CaMKII), UNC-43, function to regulate the size and morphology of presynaptic domains in C. elegans. Loss of function in unc-2, unc-36 or unc-43 resulted in slightly larger GABAergic neuromuscular junctions (NMJs), but could suppress the synaptic morphology defects found in nid-1/nidogen or ptp-3/LAR mutants. A gain-of-function mutation in unc-43 caused defects similar to those found in nid-1 mutants. Mutations in egl-19, Cav1-like, or cca-1, Cav3-like, α1 subunits, or the second α2/δ subunit, tag-180, did not suppress nid-1, suggesting a specific interaction between unc-2 and the synaptic extracellular matrix (ECM) component nidogen. Using a synaptic vesicle marker in time-lapse microscopy studies, we observed GABAergic motor neurons adding NMJ-like structures during late larval development. The synaptic bouton addition appeared to form in at least two ways: (1) de novo formation, where a cluster of vesicles appeared to coalesce, or (2) when a single punctum became enlarged and then divided to form two discrete fluorescent puncta. In comparison to wild type animals, we found unc-2 mutants exhibited reduced NMJ dynamics, with fewer observed divisions during a similar stage of development. Conclusions We identified UNC-2/UNC-36 VGCCs and UNC-43/CaMKII as regulators of C. elegans synaptogenesis. UNC-2 has a modest role in synapse formation, but a broader role in regulating dynamic changes in the size and morphology of synapses that occur during organismal development. During the late 4th larval stage (L4), wild type animals exhibit synaptic morphologies that are similar to those found in animals lacking NID-1/PTP-3 adhesion, as well as those with constitutive activation of UNC-43. Genetic evidence indicates that the VGCCs and the NID-1/PTP-3 adhesion complex provide opposing functions in synaptic development, suggesting that modulation of synaptic adhesion may underlie synapse development in C. elegans.
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Affiliation(s)
- Raymond C Caylor
- Department of Molecular Biosciences, University of Kansas, 5004 Haworth Hall, 1200 Sunnyside Ave, Lawrence, KS 66045, USA
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Miltsch SM, Krücken J, Demeler J, Janssen IJI, Krüger N, Harder A, von Samson-Himmelstjerna G. Decreased emodepside sensitivity in unc-49 γ-aminobutyric acid (GABA)-receptor-deficient Caenorhabditis elegans. Int J Parasitol 2012; 42:761-70. [PMID: 22727682 DOI: 10.1016/j.ijpara.2012.05.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/15/2012] [Accepted: 05/16/2012] [Indexed: 02/05/2023]
Abstract
Emodepside, a semi-synthetic derivative of PF1022A, belongs to a new class of anthelmintic drugs, the cyclooctadepsipeptides, and shows good efficacy against macrocyclic lactone-, levamisole- or benzimidazole-resistant nematode populations. Although putative receptors for emodepside have already been discovered, its mode of action is still not fully understood. The involvement of the γ-aminobutyric acid (GABA)-receptor on the PF1022A mode of action has previously been postulated. Therefore, a possible role of the GABA-receptor, unc-49, in the mode of action of emodepside was investigated using two different Caenorhabditis elegans in vitro assays, a motility assay and a development assay. It was found that there is a clearly reduced sensitivity against emodepside of strains carrying a GABA-receptor, unc-49, loss of function mutation compared with N2 wild type C. elegans. To transfer these results from the model system to parasitic nematodes, the Toxocara canis unc-49B cDNA sequence was identified and used in a rescue experiment. The emodepside-susceptible phenotype could be fully rescued by injection of the T. canis unc-49B cDNA sequence. We believe that this is the first functional rescue of a C. elegans mutant strain with a gene from a clade III parasitic nematode. These findings, together with the earlier data on GABA-receptor binding of PF1022A, suggest that the GABA(A)-receptor UNC-49 is associated with the emodepside mode of action. However, the only partially resistant phenotype of the loss of function mutants indicates that other pathways play a more significant role.
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Affiliation(s)
- Sandra M Miltsch
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Königsweg 67, 14163 Berlin, Germany
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Accardi MV, Beech RN, Forrester SG. Nematode cys-loop GABA receptors: biological function, pharmacology and sites of action for anthelmintics. INVERTEBRATE NEUROSCIENCE 2012; 12:3-12. [PMID: 22430311 DOI: 10.1007/s10158-012-0129-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 03/03/2012] [Indexed: 10/28/2022]
Abstract
Parasitic nematode infection of humans and livestock is a major problem globally. Attempts to control nematode populations have led to the development of several classes of anthelmintic, which target cys-loop ligand-gated ion channels. Unlike the vertebrate nervous system, the nematode nervous system possesses a large and diversified array of ligand-gated chloride channels that comprise key components of the inhibitory neurotransmission system. In particular, cys-loop GABA receptors have evolved to play many fundamental roles in nematode behaviour such as locomotion. Analysis of the genomes of several free-living and parasitic nematodes suggests that there are several groups of cys-loop GABA receptor subunits that, for the most part, are conserved among nematodes. Despite many similarities with vertebrate cys-loop GABA receptors, those in nematodes are quite distinct in sequence similarity, subunit composition and biological function. With rising anthelmintic resistance in many nematode populations worldwide, GABA receptors should become an area of increased scientific investigation in the development of the next generation of anthelmintics.
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Affiliation(s)
- Michael V Accardi
- Department of Pharmacology and Therapeutics, McGill University, Bellini Life Sciences Complex, 3649 Sir William Osler Promenade, Montreal, QC H3G 0B1, Canada
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CYY-1/cyclin Y and CDK-5 differentially regulate synapse elimination and formation for rewiring neural circuits. Neuron 2011; 70:742-57. [PMID: 21609829 DOI: 10.1016/j.neuron.2011.04.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2011] [Indexed: 12/29/2022]
Abstract
The assembly and maturation of neural circuits require a delicate balance between synapse formation and elimination. The cellular and molecular mechanisms that coordinate synaptogenesis and synapse elimination are poorly understood. In C. elegans, DD motoneurons respecify their synaptic connectivity during development by completely eliminating existing synapses and forming new synapses without changing cell morphology. Using loss- and gain-of-function genetic approaches, we demonstrate that CYY-1, a cyclin box-containing protein, drives synapse removal in this process. In addition, cyclin-dependent kinase-5 (CDK-5) facilitates new synapse formation by regulating the transport of synaptic vesicles to the sites of synaptogenesis. Furthermore, we show that coordinated activation of UNC-104/Kinesin3 and Dynein is required for patterning newly formed synapses. During the remodeling process, presynaptic components from eliminated synapses are recycled to new synapses, suggesting that signaling mechanisms and molecular motors link the deconstruction of existing synapses and the assembly of new synapses during structural synaptic plasticity.
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Chang C, Hsieh YW, Lesch BJ, Bargmann CI, Chuang CF. Microtubule-based localization of a synaptic calcium-signaling complex is required for left-right neuronal asymmetry in C. elegans. Development 2011; 138:3509-18. [PMID: 21771813 DOI: 10.1242/dev.069740] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The axons of C. elegans left and right AWC olfactory neurons communicate at synapses through a calcium-signaling complex to regulate stochastic asymmetric cell identities called AWC(ON) and AWC(OFF). However, it is not known how the calcium-signaling complex, which consists of UNC-43/CaMKII, TIR-1/SARM adaptor protein and NSY-1/ASK1 MAPKKK, is localized to postsynaptic sites in the AWC axons for this lateral interaction. Here, we show that microtubule-based localization of the TIR-1 signaling complex to the synapses regulates AWC asymmetry. Similar to unc-43, tir-1 and nsy-1 loss-of-function mutants, specific disruption of microtubules in AWC by nocodazole generates two AWC(ON) neurons. Reduced localization of UNC-43, TIR-1 and NSY-1 proteins in the AWC axons strongly correlates with the 2AWC(ON) phenotype in nocodazole-treated animals. We identified kinesin motor unc-104/kif1a mutants for enhancement of the 2AWC(ON) phenotype of a hypomorphic tir-1 mutant. Mutations in unc-104, like microtubule depolymerization, lead to a reduced level of UNC-43, TIR-1 and NSY-1 proteins in the AWC axons. In addition, dynamic transport of TIR-1 in the AWC axons is dependent on unc-104, the primary motor required for the transport of presynaptic vesicles. Furthermore, unc-104 acts non-cell autonomously in the AWC(ON) neuron to regulate the AWC(OFF) identity. Together, these results suggest a model in which UNC-104 may transport some unknown presynaptic factor(s) in the future AWC(ON) cell that non-cell autonomously control the trafficking of the TIR-1 signaling complex to postsynaptic regions of the AWC axons to regulate the AWC(OFF) identity.
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Affiliation(s)
- Chieh Chang
- Division of Developmental Biology, Children's Hospital Medical Center Research Foundation, Cincinnati, OH 45229, USA
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Accardi MV, Forrester SG. The Haemonchus contortus UNC-49B subunit possesses the residues required for GABA sensitivity in homomeric and heteromeric channels. Mol Biochem Parasitol 2011; 178:15-22. [PMID: 21524670 DOI: 10.1016/j.molbiopara.2011.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 04/04/2011] [Accepted: 04/06/2011] [Indexed: 11/16/2022]
Abstract
Hco-UNC-49 is a GABA receptor from the parasitic nematode Haemonchus contortus that has a relatively low overall sequence similarity to vertebrate GABA receptors but is very similar to the UNC-49 receptor found in the free living nematode Caenorhabditis elegans. While the nematode receptors do share >80% sequence similarity they exhibit different sensitivities to GABA. In addition, the UNC-49C subunit appears to be a positive modulator of GABA sensitivity in the H. contortus heteromeric channel, but is a negative modulator in the C. elegans heteromeric channel. The cause(s) of these differences is currently unknown since the structural elements essential for GABA sensitivity in nematode receptors have been largely unexplored. Thus, the overall aim of this study was to investigate the residues that are important for UNC-49 receptor sensitivity through the use of homology modeling, site-directed mutagenesis, and two-electrode voltage clamp. This study revealed that Met(170) in Loop B of the GABA binding-site may partially account for the observed differences in GABA receptor sensitivity between the nematode species. Residues in Loops A-D that have been reported to form the GABA binding pocket in mammalian receptors, including those forming the conserved 'aromatic box', also appear to play analogous roles in Hco-UNC-49. In addition, the two mutations that produced the most significant reduction in GABA sensitivity were R66S and Y166S. Homology modeling indicates that these two residues share a hydrogen bond and are positioned close to the carboxyl end of the GABA molecule. However, of residues examined in this study, only those on the Hco-UNC-49B subunit and not its subunit partner, Hco-UNC-49C, appear important for GABA sensitivity. Overall, results from this study suggest that the binding site of the UNC-49 heteromeric GABA receptor exhibits some differences compared to classical vertebrate GABA(A) receptors.
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Affiliation(s)
- Michael V Accardi
- University of Ontario Institute of Technology, Faculty of Science, Oshawa, ON, Canada
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Van Epps H, Dai Y, Qi Y, Goncharov A, Jin Y. Nuclear pre-mRNA 3'-end processing regulates synapse and axon development in C. elegans. Development 2010; 137:2237-50. [PMID: 20530551 DOI: 10.1242/dev.049692] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Nuclear pre-mRNA 3'-end processing is vital for the production of mature mRNA and the generation of the 3' untranslated region (UTR). However, the roles and regulation of this event in cellular development remain poorly understood. Here, we report the function of a nuclear pre-mRNA 3'-end processing pathway in synapse and axon formation in C. elegans. In a genetic enhancer screen for synaptogenesis mutants, we identified a novel polyproline-rich protein, Synaptic defective enhancer-1 (SYDN-1). Loss of function of sydn-1 causes abnormal synapse and axon development, and displays striking synergistic interactions with several genes that regulate specific aspects of synapses. SYDN-1 is required in neurons and localizes to distinct regions of the nucleus. Through a genetic suppressor screen, we found that the neuronal defects of sydn-1 mutants are suppressed by loss of function in Polyadenylation factor subunit-2 (PFS-2), a conserved WD40-repeat protein that interacts with multiple subcomplexes of the pre-mRNA 3'-end processing machinery. PFS-2 partially colocalizes with SYDN-1, and SYDN-1 influences the nuclear abundance of PFS-2. Inactivation of several members of the nuclear 3'-end processing complex suppresses sydn-1 mutants. Furthermore, lack of sydn-1 can increase the activity of 3'-end processing. Our studies provide in vivo evidence for pre-mRNA 3'-end processing in synapse and axon development and identify SYDN-1 as a negative regulator of this cellular event in neurons.
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Affiliation(s)
- Heather Van Epps
- Division of Biological Sciences, Section of Neurobiology, University of California, San Diego, CA 92093, USA
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Davis KM, Sturt BL, Friedmann AJ, Richmond JE, Bessereau JL, Grant BD, Bamber BA. Regulated lysosomal trafficking as a mechanism for regulating GABAA receptor abundance at synapses in Caenorhabditis elegans. Mol Cell Neurosci 2010; 44:307-17. [PMID: 20403442 DOI: 10.1016/j.mcn.2010.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 04/05/2010] [Accepted: 04/10/2010] [Indexed: 11/19/2022] Open
Abstract
GABA(A) receptor plasticity is important for both normal brain function and disease progression. We are studying GABA(A) receptor plasticity in Caenorhabditis elegans using a genetic approach. Acute exposure of worms to the GABA(A) agonist muscimol hyperpolarizes postsynaptic cells, causing paralysis. Worms adapt after several hours, but show uncoordinated locomotion consistent with decreased GABA signaling. Using patch-clamp and immunofluorescence approaches, we show that GABA(A) receptors are selectively removed from synapses during adaptation. Subunit mRNA levels were unchanged, suggesting a post-transcriptional mechanism. Mutants with defective lysosome function (cup-5) show elevated GABA(A) receptor levels at synapses prior to muscimol exposure. During adaptation, these receptors are removed more slowly, and accumulate in intracellular organelles positive for the late endosome marker GFP-RAB-7. These findings suggest that chronic agonist exposure increases endocytosis and lysosomal trafficking of GABA(A) receptors, leading to reduced levels of synaptic GABA(A) receptors and reduced postsynaptic GABA sensitivity.
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Affiliation(s)
- Kathleen M Davis
- Department of Biological Sciences, University of Toledo, 2801 W Bancroft St. Toledo, OH 43606, USA
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Gendrel M, Rapti G, Richmond JE, Bessereau JL. A secreted complement-control-related protein ensures acetylcholine receptor clustering. Nature 2009; 461:992-6. [PMID: 19794415 DOI: 10.1038/nature08430] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2009] [Accepted: 08/14/2009] [Indexed: 01/02/2023]
Abstract
Efficient neurotransmission at chemical synapses relies on spatial congruence between the presynaptic active zone, where synaptic vesicles fuse, and the postsynaptic differentiation, where neurotransmitter receptors concentrate. Diverse molecular systems have evolved to localize receptors at synapses, but in most cases, they rely on scaffolding proteins localized below the plasma membrane. A few systems have been suggested to control the synaptic localization of neurotransmitter receptors through extracellular interactions, such as the pentraxins that bind AMPA receptors and trigger their aggregation. However, it is not yet clear whether these systems have a central role in the organization of postsynaptic domains in vivo or rather provide modulatory functions. Here we describe an extracellular scaffold that is necessary to cluster acetylcholine receptors at neuromuscular junctions in the nematode Caenorhabditis elegans. It involves the ectodomain of the previously identified transmembrane protein LEV-10 (ref. 6) and a novel extracellular protein, LEV-9. LEV-9 is secreted by the muscle cells and localizes at cholinergic neuromuscular junctions. Acetylcholine receptors, LEV-9 and LEV-10 are interdependent for proper synaptic localization and physically interact based on biochemical evidence. Notably, the function of LEV-9 relies on eight complement control protein (CCP) domains. These domains, also called 'sushi domains', are usually found in proteins regulating complement activity in the vertebrate immune system. Because the complement system does not exist in protostomes, our results suggest that some of the numerous uncharacterized CCP proteins expressed in the mammalian brain might be directly involved in the organization of the synapse, independently from immune functions.
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Senti G, Swoboda P. Distinct isoforms of the RFX transcription factor DAF-19 regulate ciliogenesis and maintenance of synaptic activity. Mol Biol Cell 2008; 19:5517-28. [PMID: 18843046 DOI: 10.1091/mbc.e08-04-0416] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Neurons form elaborate subcellular structures such as dendrites, axons, cilia, and synapses to receive signals from their environment and to transmit them to the respective target cells. In the worm Caenorhabditis elegans, lack of the RFX transcription factor DAF-19 leads to the absence of cilia normally found on 60 sensory neurons. We now describe and functionally characterize three different isoforms of DAF-19. The short isoform DAF-19C is specifically expressed in ciliated sensory neurons and sufficient to rescue all cilia-related phenotypes of daf-19 mutants. In contrast, the long isoforms DAF-19A/B function in basically all nonciliated neurons. We discovered behavioral and cellular phenotypes in daf-19 mutants that depend on the isoforms daf-19a/b. These novel synaptic maintenance phenotypes are reminiscent of synaptic decline seen in many human neurodegenerative disorders. The C. elegans daf-19 mutant worms can thus serve as a molecular model for the mechanisms of functional neuronal decline.
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Affiliation(s)
- Gabriele Senti
- Department of Biosciences and Nutrition, Karolinska Institute, S-14157 Huddinge, Sweden
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43
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Eimer S, Gottschalk A, Hengartner M, Horvitz HR, Richmond J, Schafer WR, Bessereau JL. Regulation of nicotinic receptor trafficking by the transmembrane Golgi protein UNC-50. EMBO J 2007; 26:4313-23. [PMID: 17853888 PMCID: PMC2034668 DOI: 10.1038/sj.emboj.7601858] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Accepted: 08/22/2007] [Indexed: 01/21/2023] Open
Abstract
Nicotinic acetylcholine receptors (AChRs) are pentameric ligand-gated ion channels that mediate fast synaptic transmission at the neuromuscular junction (NMJ). After assembly in the endoplasmic reticulum (ER), AChRs must be transported to the plasma membrane through the secretory apparatus. Little is known about specific molecules that mediate this transport. Here we identify a gene that is required for subtype-specific trafficking of assembled nicotinic AChRs in Caenorhabditis elegans. unc-50 encodes an evolutionarily conserved integral membrane protein that localizes to the Golgi apparatus. In the absence of UNC-50, a subset of AChRs present in body-wall muscle are sorted to the lysosomal system and degraded. However, the trafficking of a second AChR type and of GABA ionotropic receptors expressed in the same muscle cells is not affected in unc-50 mutants. These results suggest that, in addition to ER quality control, assembled AChRs are sorted within the Golgi system by a mechanism that controls the amount of cell-surface AChRs in a subtype-specific way.
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Affiliation(s)
- Stefan Eimer
- Ecole Normale Supérieure, Biology Department, Paris, France
- INSERM, U789, Biologie cellulaire de la synapse, Paris, France
| | - Alexander Gottschalk
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Michael Hengartner
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - H Robert Horvitz
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Janet Richmond
- Department of Biology, University of Illinois, Chicago, IL, USA
| | - William R Schafer
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Jean-Louis Bessereau
- Ecole Normale Supérieure, Biology Department, Paris, France
- INSERM, U789, Biologie cellulaire de la synapse, Paris, France
- Ecole Normale Supérieure, INSERM, U789, Biologie cellulaire de la synapse, 46 Rue d'Ulm, Paris 75005, France. Tel.: +33 1 44 32 23 05; Fax: +33 1 44 32 36 54; E-mail:
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44
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Fritschy JM, Panzanelli P. Molecular and synaptic organization of GABAA receptors in the cerebellum: Effects of targeted subunit gene deletions. THE CEREBELLUM 2007; 5:275-85. [PMID: 17134990 DOI: 10.1080/14734220600962805] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
GABAA receptors form heteromeric GABA-gated chloride channels assembled from a large family of subunit genes. In cerebellum, distinct GABAA receptor subtypes, differing in subunit composition, are segregated between cell types and synaptic circuits. The cerebellum therefore represents a useful system to investigate the significance of GABAA receptor heterogeneity. For instance, studies of mice carrying targeted deletion of major GABAA receptor subunit genes revealed the role of alpha subunit variants for receptor assembly, synaptic targeting, and functional properties. In addition, these studies unraveled mandatory association between certain subunits and demonstrated distinct pharmacology of receptors mediating phasic and tonic inhibition. Although some of these mutants have a profound loss of GABAA receptors, they exhibit only minor impairment of motor function, suggesting activation of compensatory mechanisms to preserve inhibitory networks in the cerebellum. These adaptations include an altered balance between phasic and tonic inhibition, activation of voltage-independent K+ conductances, and upregulation of GABAA receptors in interneurons that are not affected directly by the mutation. Deletion of the alpha1 subunit gene leads to complete loss of GABAA receptors in Purkinje cells. A striking alteration occurs in these mice, whereby presynaptic GABAergic terminals are preserved in the molecular layer but make heterologous synapses with spines, characterized by a glutamatergic-like postsynaptic density. During development of alpha1(0/0) mice, GABAergic synapses are initially formed but are replaced upon spine maturation. These findings suggest that functional GABAA receptors are required for long-term maintenance of GABAergic synapses in Purkinje cells.
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Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
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Mullen GP, Mathews EA, Saxena P, Fields SD, McManus JR, Moulder G, Barstead RJ, Quick MW, Rand JB. The Caenorhabditis elegans snf-11 gene encodes a sodium-dependent GABA transporter required for clearance of synaptic GABA. Mol Biol Cell 2006; 17:3021-30. [PMID: 16641366 PMCID: PMC1483038 DOI: 10.1091/mbc.e06-02-0155] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Sodium-dependent neurotransmitter transporters participate in the clearance and/or recycling of neurotransmitters from synaptic clefts. The snf-11 gene in Caenorhabditis elegans encodes a protein of high similarity to mammalian GABA transporters (GATs). We show here that snf-11 encodes a functional GABA transporter; SNF-11-mediated GABA transport is Na+ and Cl- dependent, has an EC50 value of 168 microM, and is blocked by the GAT1 inhibitor SKF89976A. The SNF-11 protein is expressed in seven GABAergic neurons, several additional neurons in the head and retrovesicular ganglion, and three groups of muscle cells. Therefore, all GABAergic synapses are associated with either presynaptic or postsynaptic (or both) expression of SNF-11. Although a snf-11 null mutation has no obvious effects on GABAergic behaviors, it leads to resistance to inhibitors of acetylcholinesterase. In vivo, a snf-11 null mutation blocks GABA uptake in at least a subset of GABAergic cells; in a cell culture system, all GABA uptake is abolished by the snf-11 mutation. We conclude that GABA transport activity is not essential for normal GABAergic function in C. elegans and that the localization of SNF-11 is consistent with a GABA clearance function rather than recycling.
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Affiliation(s)
- Gregory P. Mullen
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
| | - Eleanor A. Mathews
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
| | - Paurush Saxena
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2520
| | - Stephen D. Fields
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
| | - John R. McManus
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
| | - Gary Moulder
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
| | - Robert J. Barstead
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
| | - Michael W. Quick
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2520
| | - James B. Rand
- *Program in Molecular, Cell, and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104; and
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46
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Francis MM, Evans SP, Jensen M, Madsen DM, Mancuso J, Norman KR, Maricq AV. The Ror receptor tyrosine kinase CAM-1 is required for ACR-16-mediated synaptic transmission at the C. elegans neuromuscular junction. Neuron 2005; 46:581-94. [PMID: 15944127 DOI: 10.1016/j.neuron.2005.04.010] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2003] [Revised: 02/28/2005] [Accepted: 04/15/2005] [Indexed: 11/15/2022]
Abstract
Nicotinic (cholinergic) neurotransmission plays a critical role in the vertebrate nervous system, underlies nicotine addiction, and nicotinic receptor dysfunction leads to neurological disorders. The C. elegans neuromuscular junction (NMJ) shares many characteristics with neuronal synapses, including multiple classes of postsynaptic currents. Here, we identify two genes required for the major excitatory current found at the C. elegans NMJ: acr-16, which encodes a nicotinic AChR subunit homologous to the vertebrate alpha7 subunit, and cam-1, which encodes a Ror receptor tyrosine kinase. acr-16 mutants lack fast cholinergic current at the NMJ and exhibit synthetic behavioral deficits with other known AChR mutants. In cam-1 mutants, ACR-16 is mislocalized and ACR-16-dependent currents are disrupted. The postsynaptic deficit in cam-1 mutants is accompanied by alterations in the distribution of cholinergic vesicles and associated synaptic proteins. We hypothesize that CAM-1 contributes to the localization or stabilization of postsynaptic ACR-16 receptors and presynaptic release sites.
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Affiliation(s)
- Michael M Francis
- Department of Biology, University of Utah, Salt Lake City 84112, USA
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Bamber BA, Richmond JE, Otto JF, Jorgensen EM. The composition of the GABA receptor at the Caenorhabditis elegans neuromuscular junction. Br J Pharmacol 2005; 144:502-9. [PMID: 15655525 PMCID: PMC1576029 DOI: 10.1038/sj.bjp.0706052] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The unc-49 gene of the nematode Caenorhabditis elegans encodes three gamma-aminobutyric acid type A (GABA(A)) receptor subunits. Two of these, UNC-49B and UNC-49C, are expressed at high abundance and co-localize at the neuromuscular junction. 2. The UNC-49B subunit is sufficient to form a GABA(A) receptor in vitro and in vivo. Furthermore, all loss-of-function unc-49 alleles lack functional UNC-49B. No mutations specifically inactivate UNC-49C. Thus, UNC-49C appears to be dispensable for receptor function; however, UNC-49C has been conserved among different nematode species, suggesting it plays a necessary role. 3. To ascertain whether UNC-49C is part of the GABA(A) receptor in vivo, we performed patch-clamp electrophysiology on C. elegans muscle cells. Sensitivity to GABA, and to the antagonists picrotoxin and pregnenolone sulfate, matched the UNC-49B/C heteromer rather than the UNC-49B homomer, for both exogenous and synaptically-released GABA. 4. The synaptic localization of UNC-49C requires the presence of UNC-49B, indicative of a physical association between the two subunits in vivo. Thus, the in vivo receptor is an UNC-49B/C heteromer. 5. UNC-49C plays a negative modulatory role. Using the rapid ligand-exchange technique in vitro, we determined that UNC-49C causes accelerated receptor desensitization. Previously, UNC-49C was shown to reduce single-channel conductance in UNC-49B/C heteromers. Thus, the function of UNC-49B is to provide GABA responsiveness and localization to synapses, while the function of UNC-49C is to negatively modulate receptor function and precisely shape inhibitory postsynaptic currents.
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Affiliation(s)
- Bruce A Bamber
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, U.S.A
| | - Janet E Richmond
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, U.S.A
| | - James F Otto
- Department of Pharmacology and Toxicology, University of Utah, 30 South 2000 East, Salt Lake City, UT 84112-0840, U.S.A
| | - Erik M Jorgensen
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, U.S.A
- Author for correspondence:
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Shan G, Kim K, Li C, Walthall WW. Convergent genetic programs regulate similarities and differences between related motor neuron classes in Caenorhabditis elegans. Dev Biol 2005; 280:494-503. [PMID: 15882588 DOI: 10.1016/j.ydbio.2005.01.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 01/27/2005] [Accepted: 01/31/2005] [Indexed: 11/17/2022]
Abstract
How do genetic programs create features common to a specific cell or tissue type while generating modifications necessary for functional diversification? We have addressed this question using the nematode Caenorhabditis elegans. The dorsal D (DD) and ventral D (VD) motorneurons (mns), referred to collectively as the D mns, compose a cross-inhibitory network that contributes to the animal's sinuous locomotion. The D mns share a number of structural and functional features, but are distinguished from one another by their synaptic patterns and the expression of a neuropeptide gene. Our findings suggest that the similarities and differences are generated at the transcriptional level. UNC-30 contains a homeodomain and activates structural and functional genes expressed in both classes. UNC-55 is a nuclear receptor expressed in the VD mns that is necessary for generating features that distinguish the two classes of D mns from one another. In unc-55 mutants, the VD mns adopt the DD mn synaptic pattern and peptide expression profile. Conversely, ectopic expression of unc-55 in the DD mns causes them to adopt VD mn features. The promoter of the neuropeptide gene expressed in the DD mns contains putative binding sites for both UNC-30 and UNC-55; alteration of these sites suggests that UNC-55 represses the ability of UNC-30 to activate a subset of genes that are expressed in the DD mns but not in the VD mns. Thus UNC-55 acts as a switch for the features that distinguish these two functionally related classes of mns.
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Affiliation(s)
- Ge Shan
- Department of Biology, Georgia State University, Atlanta, 30302-4010, USA
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Gally C, Eimer S, Richmond JE, Bessereau JL. A transmembrane protein required for acetylcholine receptor clustering in Caenorhabditis elegans. Nature 2004; 431:578-82. [PMID: 15457263 PMCID: PMC3781939 DOI: 10.1038/nature02893] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 07/30/2004] [Indexed: 02/05/2023]
Abstract
Clustering neurotransmitter receptors at the synapse is crucial for efficient neurotransmission. Here we identify a Caenorhabditis elegans locus, lev-10, required for postsynaptic aggregation of ionotropic acetylcholine receptors (AChRs). lev-10 mutants were identified on the basis of weak resistance to the anthelminthic drug levamisole, a nematode-specific cholinergic agonist that activates AChRs present at neuromuscular junctions (NMJs) resulting in muscle hypercontraction and death at high concentrations. In lev-10 mutants, the density of levamisole-sensitive AChRs at NMJs is markedly reduced, yet the number of functional AChRs present at the muscle cell surface remains unchanged. LEV-10 is a transmembrane protein localized to cholinergic NMJs and required in body-wall muscles for AChR clustering. We also show that the LEV-10 extracellular region, containing five predicted CUB domains and one LDLa domain, is sufficient to rescue AChR aggregation in lev-10 mutants. This suggests a mechanism for AChR clustering that relies on extracellular protein-protein interactions. Such a mechanism is likely to be evolutionarily conserved because CUB/LDL transmembrane proteins similar to LEV-10, but lacking any assigned function, are expressed in the mammalian nervous system and might be used to cluster ionotropic receptors in vertebrates.
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Affiliation(s)
- Christelle Gally
- INSERM U.497, Ecole Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France
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50
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Abstract
GABA neurotransmission requires a specialized set of proteins to synthesize, transport or respond to GABA. This article reviews results from a genetic strategy in the nematode Caenorhabditis elegans designed to identify the genes responsible for these activities. These studies identified mutations in genes encoding five different proteins: the biosynthetic enzyme for GABA, the vesicular GABA transporter, a transcription factor that determines GABA neuron identity, a classic inhibitory GABA receptor and a novel excitatory GABA receptor. This review discusses the strategy employed to identify these genes as well as the conclusions about GABA transmission derived from study of the mutant phenotypes.
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Affiliation(s)
- Kim Schuske
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, USA
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