1
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Lo JY, Adam KM, Garrison JL. Neuropeptide inactivation regulates egg-laying behavior to influence reproductive health in Caenorhabditis elegans. Curr Biol 2024; 34:4715-4728.e4. [PMID: 39395417 DOI: 10.1016/j.cub.2024.09.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 07/11/2024] [Accepted: 09/23/2024] [Indexed: 10/14/2024]
Abstract
Neural communication requires both fast-acting neurotransmitters and neuromodulators that function on slower timescales to communicate. Endogenous bioactive peptides, often called "neuropeptides," comprise the largest and most diverse class of neuromodulators that mediate crosstalk between the brain and peripheral tissues to regulate physiology and behaviors conserved across the animal kingdom. Neuropeptide signaling can be terminated through receptor binding and internalization or degradation by extracellular enzymes called neuropeptidases. Inactivation by neuropeptidases can shape the dynamics of signaling in vivo by specifying both the duration of signaling and the anatomic path neuropeptides can travel before they are degraded. For most neuropeptides, the identity of the relevant inactivating peptidase(s) is unknown. Here, we established a screening platform in C. elegans utilizing mass spectrometry-based peptidomics to discover neuropeptidases and simultaneously profile the in vivo specificity of these enzymes against each of more than 250 endogenous peptides. We identified NEP-2, a worm ortholog of the mammalian peptidase neprilysin-2, and demonstrated that it regulates specific neuropeptides, including those in the egg-laying circuit. We found that NEP-2 is required in muscle cells to regulate signals from neurons to modulate both behavior and health in the reproductive system. Taken together, our results demonstrate that peptidases, which are an important node of regulation in neuropeptide signaling, affect the dynamics of signaling to impact behavior, physiology, and aging.
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Affiliation(s)
- Jacqueline Y Lo
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945, USA
| | - Katelyn M Adam
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945, USA; Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089, USA
| | - Jennifer L Garrison
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945, USA; Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089, USA; Cellular and Molecular Pharmacology, University of California, San Francisco, 600 16th Street, San Francisco, CA 94158, USA; Center for Healthy Aging in Women, 8001 Redwood Boulevard, Novato, CA 94945, USA; Productive Health Global Consortium, 8001 Redwood Boulevard, Novato, CA 94945, USA.
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2
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Butt A, Van Damme S, Santiago E, Olson A, Beets I, Koelle MR. Neuropeptide and serotonin co-transmission sets the activity pattern in the C. elegans egg-laying circuit. Curr Biol 2024; 34:4704-4714.e5. [PMID: 39395419 DOI: 10.1016/j.cub.2024.07.064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/08/2024] [Accepted: 07/17/2024] [Indexed: 10/14/2024]
Abstract
Neurons typically release both a neurotransmitter and one or more neuropeptides, but how these signals are integrated within neural circuits to generate and tune behaviors remains poorly understood. We studied how the two hermaphrodite-specific neurons (HSNs) activate the egg-laying circuit of Caenorhabditis elegans by releasing both the neurotransmitter serotonin and NLP-3 neuropeptides. Egg laying occurs in a temporal pattern with approximately 2-min active phases, during which eggs are laid, separated by approximately 20-min inactive phases, during which no eggs are laid. To understand how serotonin and NLP-3 neuropeptides together help produce this behavior pattern, we identified the G-protein-coupled receptor neuropeptide receptor 36 (NPR-36) as an NLP-3 neuropeptide receptor using genetic and molecular experiments. We found that NPR-36 is expressed in, and promotes egg laying within, the egg-laying muscle cells, the same cells where two serotonin receptors also promote egg laying. During the active phase, when HSN activity is high, we found that serotonin and NLP-3 neuropeptides each have a different effect on the timing of egg laying. During the inactive phase, HSN activity is low, which may result in release of only serotonin, yet mutants lacking either serotonin or nlp-3 signaling have longer inactive phases. This suggests that NLP-3 peptide signaling may persist through the inactive phase to help serotonin signaling terminate the inactive phase. We propose a model for neural circuit function in which multiple signals with short- and long-lasting effects compete to generate and terminate persistent internal states, thus patterning a behavior over tens of minutes.
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Affiliation(s)
- Allison Butt
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06510, USA
| | | | - Emerson Santiago
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06510, USA
| | - Andrew Olson
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06510, USA
| | - Isabel Beets
- Department of Biology, KU Leuven, 3000 Leuven, Belgium
| | - Michael R Koelle
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06510, USA.
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3
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Wang C, Vidal B, Sural S, Loer C, Aguilar GR, Merritt DM, Toker IA, Vogt MC, Cros CC, Hobert O. A neurotransmitter atlas of C. elegans males and hermaphrodites. eLife 2024; 13:RP95402. [PMID: 39422452 PMCID: PMC11488851 DOI: 10.7554/elife.95402] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2024] Open
Abstract
Mapping neurotransmitter identities to neurons is key to understanding information flow in a nervous system. It also provides valuable entry points for studying the development and plasticity of neuronal identity features. In the Caenorhabditis elegans nervous system, neurotransmitter identities have been largely assigned by expression pattern analysis of neurotransmitter pathway genes that encode neurotransmitter biosynthetic enzymes or transporters. However, many of these assignments have relied on multicopy reporter transgenes that may lack relevant cis-regulatory information and therefore may not provide an accurate picture of neurotransmitter usage. We analyzed the expression patterns of 16 CRISPR/Cas9-engineered knock-in reporter strains for all main types of neurotransmitters in C. elegans (glutamate, acetylcholine, GABA, serotonin, dopamine, tyramine, and octopamine) in both the hermaphrodite and the male. Our analysis reveals novel sites of expression of these neurotransmitter systems within both neurons and glia, as well as non-neural cells, most notably in gonadal cells. The resulting expression atlas defines neurons that may be exclusively neuropeptidergic, substantially expands the repertoire of neurons capable of co-transmitting multiple neurotransmitters, and identifies novel sites of monoaminergic neurotransmitter uptake. Furthermore, we also observed unusual co-expression patterns of monoaminergic synthesis pathway genes, suggesting the existence of novel monoaminergic transmitters. Our analysis results in what constitutes the most extensive whole-animal-wide map of neurotransmitter usage to date, paving the way for a better understanding of neuronal communication and neuronal identity specification in C. elegans.
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Affiliation(s)
- Chen Wang
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Berta Vidal
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Surojit Sural
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Curtis Loer
- Department of Biology, University of San DiegoSan DiegoUnited States
| | - G Robert Aguilar
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Daniel M Merritt
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Itai Antoine Toker
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Merly C Vogt
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Cyril C Cros
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
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4
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Wang C, Vidal B, Sural S, Loer C, Aguilar GR, Merritt DM, Toker IA, Vogt MC, Cros C, Hobert O. A neurotransmitter atlas of C. elegans males and hermaphrodites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.24.573258. [PMID: 38895397 PMCID: PMC11185579 DOI: 10.1101/2023.12.24.573258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Mapping neurotransmitter identities to neurons is key to understanding information flow in a nervous system. It also provides valuable entry points for studying the development and plasticity of neuronal identity features. In the C. elegans nervous system, neurotransmitter identities have been largely assigned by expression pattern analysis of neurotransmitter pathway genes that encode neurotransmitter biosynthetic enzymes or transporters. However, many of these assignments have relied on multicopy reporter transgenes that may lack relevant cis-regulatory information and therefore may not provide an accurate picture of neurotransmitter usage. We analyzed the expression patterns of 16 CRISPR/Cas9-engineered knock-in reporter strains for all main types of neurotransmitters in C. elegans (glutamate, acetylcholine, GABA, serotonin, dopamine, tyramine, and octopamine) in both the hermaphrodite and the male. Our analysis reveals novel sites of expression of these neurotransmitter systems within both neurons and glia, as well as non-neural cells. The resulting expression atlas defines neurons that may be exclusively neuropeptidergic, substantially expands the repertoire of neurons capable of co-transmitting multiple neurotransmitters, and identifies novel neurons that uptake monoaminergic neurotransmitters. Furthermore, we also observed unusual co-expression patterns of monoaminergic synthesis pathway genes, suggesting the existence of novel monoaminergic transmitters. Our analysis results in what constitutes the most extensive whole-animal-wide map of neurotransmitter usage to date, paving the way for a better understanding of neuronal communication and neuronal identity specification in C. elegans.
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Affiliation(s)
- Chen Wang
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Berta Vidal
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Surojit Sural
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Curtis Loer
- Department of Biology, University of San Diego, San Diego, California, USA
| | - G. Robert Aguilar
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Daniel M. Merritt
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Itai Antoine Toker
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Merly C. Vogt
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Cyril Cros
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, USA
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5
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Mignerot L, Gimond C, Bolelli L, Bouleau C, Sandjak A, Boulin T, Braendle C. Natural variation in the Caenorhabditis elegans egg-laying circuit modulates an intergenerational fitness trade-off. eLife 2024; 12:RP88253. [PMID: 38564369 PMCID: PMC10987095 DOI: 10.7554/elife.88253] [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] [Indexed: 04/04/2024] Open
Abstract
Evolutionary transitions from egg laying (oviparity) to live birth (viviparity) are common across various taxa. Many species also exhibit genetic variation in egg-laying mode or display an intermediate mode with laid eggs containing embryos at various stages of development. Understanding the mechanistic basis and fitness consequences of such variation remains experimentally challenging. Here, we report highly variable intra-uterine egg retention across 316 Caenorhabditis elegans wild strains, some exhibiting strong retention, followed by internal hatching. We identify multiple evolutionary origins of such phenotypic extremes and pinpoint underlying candidate loci. Behavioral analysis and genetic manipulation indicates that this variation arises from genetic differences in the neuromodulatory architecture of the egg-laying circuitry. We provide experimental evidence that while strong egg retention can decrease maternal fitness due to in utero hatching, it may enhance offspring protection and confer a competitive advantage. Therefore, natural variation in C. elegans egg-laying behaviour can alter an apparent trade-off between different fitness components across generations. Our findings highlight underappreciated diversity in C. elegans egg-laying behavior and shed light on its fitness consequences. This behavioral variation offers a promising model to elucidate the molecular changes in a simple neural circuit underlying evolutionary shifts between alternative egg-laying modes in invertebrates.
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Affiliation(s)
| | | | | | | | - Asma Sandjak
- Université Côte d’Azur, CNRS, Inserm, IBVNiceFrance
| | - Thomas Boulin
- Institut NeuroMyoGène, CNRS, Inserm, Université de LyonLyonFrance
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6
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Olson AC, Butt AM, Christie NTM, Shelar A, Koelle MR. Multiple Subthreshold GPCR Signals Combined by the G-Proteins Gα q and Gα s Activate the Caenorhabditis elegans Egg-Laying Muscles. J Neurosci 2023; 43:3789-3806. [PMID: 37055179 PMCID: PMC10219013 DOI: 10.1523/jneurosci.2301-22.2023] [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: 12/14/2022] [Revised: 03/21/2023] [Accepted: 04/07/2023] [Indexed: 04/15/2023] Open
Abstract
Individual neurons or muscle cells express many G-protein-coupled receptors (GPCRs) for neurotransmitters and neuropeptides, yet it remains unclear how cells integrate multiple GPCR signals that all must activate the same few G-proteins. We analyzed this issue in the Caenorhabditis elegans egg-laying system, where multiple GPCRs on muscle cells promote contraction and egg laying. We genetically manipulated individual GPCRs and G-proteins specifically in these muscle cells within intact animals and then measured egg laying and muscle calcium activity. Two serotonin GPCRs on the muscle cells, Gαq-coupled SER-1 and Gαs-coupled SER-7, together promote egg laying in response to serotonin. We found that signals produced by either SER-1/Gαq or SER-7/Gαs alone have little effect, but these two subthreshold signals combine to activate egg laying. We then transgenically expressed natural or designer GPCRs in the muscle cells and found that their subthreshold signals can also combine to induce muscle activity. However, artificially inducing strong signaling through just one of these GPCRs can be sufficient to induce egg laying. Knocking down Gαq and Gαs in the egg-laying muscle cells induced egg-laying defects that were stronger than those of a SER-1/SER-7 double knockout, indicating that additional endogenous GPCRs also activate the muscle cells. These results show that in the egg-laying muscles multiple GPCRs for serotonin and other signals each produce weak effects that individually do not result in strong behavioral outcomes. However, they combine to produce sufficient levels of Gαq and Gαs signaling to promote muscle activity and egg laying.SIGNIFICANCE STATEMENT How can neurons and other cells gather multiple independent pieces of information from the soup of chemical signals in their environment and compute an appropriate response? Most cells express >20 GPCRs that each receive one signal and transmit that information through three main types of G-proteins. We analyzed how this machinery generates responses by studying the egg-laying system of C. elegans, where serotonin and multiple other signals act through GPCRs on the egg-laying muscles to promote muscle activity and egg laying. We found that individual GPCRs within an intact animal each generate effects too weak to activate egg laying. However, combined signaling from multiple GPCR types reaches a threshold capable of activating the muscle cells.
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Affiliation(s)
- Andrew C Olson
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
| | - Allison M Butt
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
| | - Nakeirah T M Christie
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
| | - Ashish Shelar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
| | - Michael R Koelle
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510
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7
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Porta-de-la-Riva M, Gonzalez AC, Sanfeliu-Cerdán N, Karimi S, Malaiwong N, Pidde A, Morales-Curiel LF, Fernandez P, González-Bolívar S, Hurth C, Krieg M. Neural engineering with photons as synaptic transmitters. Nat Methods 2023; 20:761-769. [PMID: 37024651 DOI: 10.1038/s41592-023-01836-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 03/03/2023] [Indexed: 04/08/2023]
Abstract
Neuronal computation is achieved through connections of individual neurons into a larger network. To expand the repertoire of endogenous cellular communication, we developed a synthetic, photon-assisted synaptic transmission (PhAST) system. PhAST is based on luciferases and channelrhodopsins that enable the transmission of a neuronal state across space, using photons as neurotransmitters. PhAST overcomes synaptic barriers and rescues the behavioral deficit of a glutamate mutant with conditional, calcium-triggered photon emission between two neurons of the Caenorhabditis elegans nociceptive avoidance circuit. To demonstrate versatility and flexibility, we generated de novo synaptic transmission between two unconnected cells in a sexually dimorphic neuronal circuit, suppressed endogenous nocifensive response through activation of an anion channelrhodopsin and switched attractive to aversive behavior in an olfactory circuit. Finally, we applied PhAST to dissect the calcium dynamics of the temporal pattern generator in a motor circuit for ovipositioning. In summary, we established photon-based synaptic transmission that facilitates the modification of animal behavior.
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Affiliation(s)
| | | | | | - Shadi Karimi
- Institut de Ciències Fotòniques, Castelldefels, Spain
| | | | | | | | | | | | - Cedric Hurth
- Institut de Ciències Fotòniques, Castelldefels, Spain
| | - Michael Krieg
- Institut de Ciències Fotòniques, Castelldefels, Spain.
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8
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da Silva TC, da Silveira TL, Dos Santos LV, Arantes LP, Martins RP, Soares FAA, Dalla Corte CL. Exogenous Adenosine Modulates Behaviors and Stress Response in Caenorhabditis elegans. Neurochem Res 2023; 48:117-130. [PMID: 36018438 DOI: 10.1007/s11064-022-03727-5] [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: 01/19/2022] [Revised: 07/14/2022] [Accepted: 08/15/2022] [Indexed: 01/11/2023]
Abstract
Adenosine, a purine nucleoside with neuromodulatory actions, is part of the purinergic signaling system (PSS). Caenorhabditis elegans is a free-living nematode found in soil, used in biological research for its advantages as an alternative experimental model. Since there is a lack of evidence of adenosine's direct actions and the PSS's participation in this animal, such an investigation is necessary. In this research, we aimed to test the effects of acute and chronic adenosine at 1, 5, and 10 mM on nematode's behaviors, morphology, survival after stress conditions, and on pathways related to the response to oxidative stress (DAF-16/FOXO and SKN-1) and genes products downstream these pathways (SOD-3, HSP-16.2, and GCS-1). Acute or chronic adenosine did not alter the worms' morphology analyzed by the worms' length, width, and area, nor interfered with reproductive behavior. On the other hand, acute and chronic adenosine modulated the defecation rate, pharyngeal pumping rate, and locomotion, in addition, to interacting with stress response pathways in C. elegans. Adenosine interfered in the speed and mobility of the worms analyzed. In addition, both acute and chronic adenosine presented modulatory effects on oxidative stress response signaling. Acute adenosine prevented the heat-induced-increase of DAF-16 activation and SOD-3 levels, while chronic adenosine per se induced DAF-16 activation and prevented heat-induced-increase of HSP-16.2 and SKN-1 levels. Together, these results indicate that exogenous adenosine has physiological and biochemical effects on C. elegans and describes possible purinergic signaling in worms.
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Affiliation(s)
- Thayanara Cruz da Silva
- Departamento de Bioquímica e Biologia Molecular, Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Tássia Limana da Silveira
- Departamento de Bioquímica e Biologia Molecular, Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Luiza Venturini Dos Santos
- Departamento de Bioquímica e Biologia Molecular, Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Leticia Priscila Arantes
- Instituto Latino-Americano de Ciências da Vida e da Natureza, Universidade Federal da Integração Latino-Americana, Foz do Iguaçu, Paraná, 85866-000, Brazil
| | - Rodrigo Pereira Martins
- Departamento de Bioquímica e Biologia Molecular, Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Félix Alexandre Antunes Soares
- Departamento de Bioquímica e Biologia Molecular, Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Cristiane Lenz Dalla Corte
- Departamento de Bioquímica e Biologia Molecular, Programa de Pós-graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Av. Roraima nº 1000, Camobi, Santa Maria, RS, 97105-900, Brazil.
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9
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Rosikon KD, Bone MC, Lawal HO. Regulation and modulation of biogenic amine neurotransmission in Drosophila and Caenorhabditis elegans. Front Physiol 2023; 14:970405. [PMID: 36875033 PMCID: PMC9978017 DOI: 10.3389/fphys.2023.970405] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/23/2023] [Indexed: 02/18/2023] Open
Abstract
Neurotransmitters are crucial for the relay of signals between neurons and their target. Monoamine neurotransmitters dopamine (DA), serotonin (5-HT), and histamine are found in both invertebrates and mammals and are known to control key physiological aspects in health and disease. Others, such as octopamine (OA) and tyramine (TA), are abundant in invertebrates. TA is expressed in both Caenorhabditis elegans and Drosophila melanogaster and plays important roles in the regulation of essential life functions in each organism. OA and TA are thought to act as the mammalian homologs of epinephrine and norepinephrine respectively, and when triggered, they act in response to the various stressors in the fight-or-flight response. 5-HT regulates a wide range of behaviors in C. elegans including egg-laying, male mating, locomotion, and pharyngeal pumping. 5-HT acts predominantly through its receptors, of which various classes have been described in both flies and worms. The adult brain of Drosophila is composed of approximately 80 serotonergic neurons, which are involved in modulation of circadian rhythm, feeding, aggression, and long-term memory formation. DA is a major monoamine neurotransmitter that mediates a variety of critical organismal functions and is essential for synaptic transmission in invertebrates as it is in mammals, in which it is also a precursor for the synthesis of adrenaline and noradrenaline. In C. elegans and Drosophila as in mammals, DA receptors play critical roles and are generally grouped into two classes, D1-like and D2-like based on their predicted coupling to downstream G proteins. Drosophila uses histamine as a neurotransmitter in photoreceptors as well as a small number of neurons in the CNS. C. elegans does not use histamine as a neurotransmitter. Here, we review the comprehensive set of known amine neurotransmitters found in invertebrates, and discuss their biological and modulatory functions using the vast literature on both Drosophila and C. elegans. We also suggest the potential interactions between aminergic neurotransmitters systems in the modulation of neurophysiological activity and behavior.
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Affiliation(s)
- Katarzyna D Rosikon
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Megan C Bone
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Hakeem O Lawal
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
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10
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Ptchd1 mediates opioid tolerance via cholesterol-dependent effects on μ-opioid receptor trafficking. Nat Neurosci 2022; 25:1179-1190. [PMID: 35982154 DOI: 10.1038/s41593-022-01135-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/11/2022] [Indexed: 11/09/2022]
Abstract
Repeated exposure to opioids causes tolerance, which limits their analgesic utility and contributes to overdose and abuse liability. However, the molecular mechanisms underpinning tolerance are not well understood. Here, we used a forward genetic screen in Caenorhabditis elegans for unbiased identification of genes regulating opioid tolerance which revealed a role for PTR-25/Ptchd1. We found that PTR-25/Ptchd1 controls μ-opioid receptor trafficking and that these effects were mediated by the ability of PTR-25/Ptchd1 to control membrane cholesterol content. Electrophysiological studies showed that loss of Ptchd1 in mice reduced opioid-induced desensitization of neurons in several brain regions and the peripheral nervous system. Mice and C. elegans lacking Ptchd1/PTR-25 display similarly augmented responses to opioids. Ptchd1 knockout mice fail to develop analgesic tolerance and have greatly diminished somatic withdrawal. Thus, we propose that Ptchd1 plays an evolutionarily conserved role in protecting the μ-opioid receptor against overstimulation.
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11
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Dhakal P, Chaudhry SI, Signorelli R, Collins KM. Serotonin signals through postsynaptic Gαq, Trio RhoGEF, and diacylglycerol to promote Caenorhabditis elegans egg-laying circuit activity and behavior. Genetics 2022; 221:iyac084. [PMID: 35579369 PMCID: PMC9252285 DOI: 10.1093/genetics/iyac084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/26/2022] [Indexed: 11/12/2022] Open
Abstract
Activated Gαq signals through phospholipase-Cβ and Trio, a Rho GTPase exchange factor (RhoGEF), but how these distinct effector pathways promote cellular responses to neurotransmitters like serotonin remains poorly understood. We used the egg-laying behavior circuit of Caenorhabditis elegans to determine whether phospholipase-Cβ and Trio mediate serotonin and Gαq signaling through independent or related biochemical pathways. Our genetic rescue experiments suggest that phospholipase-Cβ functions in neurons while Trio Rho GTPase exchange factor functions in both neurons and the postsynaptic vulval muscles. While Gαq, phospholipase-Cβ, and Trio Rho GTPase exchange factor mutants fail to lay eggs in response to serotonin, optogenetic stimulation of the serotonin-releasing HSN neurons restores egg laying only in phospholipase-Cβ mutants. Phospholipase-Cβ mutants showed vulval muscle Ca2+ transients while strong Gαq and Trio Rho GTPase exchange factor mutants had little or no vulval muscle Ca2+ activity. Treatment with phorbol 12-myristate 13-acetate that mimics 1,2-diacylglycerol, a product of PIP2 hydrolysis, rescued egg-laying circuit activity and behavior defects of Gαq signaling mutants, suggesting both phospholipase-C and Rho signaling promote synaptic transmission and egg laying via modulation of 1,2-diacylglycerol levels. 1,2-Diacylglycerol activates effectors including UNC-13; however, we find that phorbol esters, but not serotonin, stimulate egg laying in unc-13 and phospholipase-Cβ mutants. These results support a model where serotonin signaling through Gαq, phospholipase-Cβ, and UNC-13 promotes neurotransmitter release, and that serotonin also signals through Gαq, Trio Rho GTPase exchange factor, and an unidentified, phorbol 12-myristate 13-acetate-responsive effector to promote postsynaptic muscle excitability. Thus, the same neuromodulator serotonin can signal in distinct cells and effector pathways to coordinate activation of a motor behavior circuit.
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Affiliation(s)
- Pravat Dhakal
- Department of Biology, University of Miami, Coral Gables, FL 33146, USA
| | - Sana I Chaudhry
- Department of Biology, University of Miami, Coral Gables, FL 33146, USA
| | | | - Kevin M Collins
- Department of Biology, University of Miami, Coral Gables, FL 33146, USA
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12
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Muthubharathi BC, Balasubramaniam B, Mir DA, Ravichandiran V, Balamurugan K. Physiological and Metabolite Alterations Associated with Neuronal Signals of Caenorhabditis elegans during Cronobacter sakazakii Infections. ACS Chem Neurosci 2021; 12:4336-4349. [PMID: 34704733 DOI: 10.1021/acschemneuro.1c00559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Metabolomic reprogramming plays a crucial role in the activation of several regulatory mechanisms including neuronal responses of the host. In the present study, alterations at physiological and biochemical levels were initially assessed to monitor the impact of the candidate pathogen Cronobacter sakazakii on the nematode host Caenorhabditis elegans. The abnormal behavioral responses were observed in infected worms in terms of hyperosmolarity and high viscous chemicals. The microscopic observations indicated reduction in egg laying and internal hatching of larvae in the host. An increased level of total reactive oxygen species and reduction in antioxidant agents such as glutathione and catalase were observed. These observations suggested the severe effect of C. sakazakii infection on C. elegans. To understand the small molecules which likely mediated neurotransmission, the whole metabolome of C. elegans during the infection of C. sakazakii was analyzed using liquid chromatography-mass spectrometry. A decrease in the quantity of methyl dopamine and palmitoyl dopamine and an increase in hydroxyl dopamine suggested that reduction in dopamine reuptake and dopamine neuronal stress. The disordered dopaminergic transmission during infection was confirmed using transgenic C. elegans by microscopic observation of Dat-1 protein expression. In addition, reduction in arachidonic acid and short-chain fatty acids revealed their effect on lipid droplet formation as well as neuronal damage. An increase in the quantity of stearoyl CoA underpinned the higher accumulation of lipid droplets in the host. On the other hand, an increased level of metabolites such as palmitoyl serotonin, citalopram N-oxide, and N-acyl palmitoyl serotonin revealed serotonin-mediated potential response for neuroprotection, cytotoxicity, and cellular damage. Based on the metabolomic data, the genes correspond to small molecules involved in biosynthesis and transportation of candidate neurotransmitters were validated through relative gene expression.
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Affiliation(s)
| | | | - Dilawar Ahmad Mir
- Department of Biotechnology, Science Campus, Alagappa University, Karaikudi 630003, India
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13
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Goodwin SF, Hobert O. Molecular Mechanisms of Sexually Dimorphic Nervous System Patterning in Flies and Worms. Annu Rev Cell Dev Biol 2021; 37:519-547. [PMID: 34613817 DOI: 10.1146/annurev-cellbio-120319-115237] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Male and female brains display anatomical and functional differences. Such differences are observed in species across the animal kingdom, including humans, but have been particularly well-studied in two classic animal model systems, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans. Here we summarize recent advances in understanding how the worm and fly brain acquire sexually dimorphic features during development. We highlight the advantages of each system, illustrating how the precise anatomical delineation of sexual dimorphisms in worms has enabled recent analysis into how these dimorphisms become specified during development, and how focusing on sexually dimorphic neurons in the fly has enabled an increasingly detailed understanding of sex-specific behaviors.
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Affiliation(s)
- Stephen F Goodwin
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford OX1 3SR, United Kingdom;
| | - Oliver Hobert
- Department of Biological Sciences and Howard Hughes Medical Institute, Columbia University, New York, NY 10027, USA;
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14
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Emerson S, Hay M, Smith M, Granger R, Blauch D, Snyder N, El Bejjani R. Acetylcholine signaling genes are required for cocaine-stimulated egg laying in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2021; 11:jkab143. [PMID: 33914087 PMCID: PMC8763240 DOI: 10.1093/g3journal/jkab143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 04/20/2021] [Indexed: 11/23/2022]
Abstract
The toxicity and addictive liability associated with cocaine abuse are well-known. However, its mode of action is not completely understood, and effective pharmacotherapeutic interventions remain elusive. The cholinergic effects of cocaine on acetylcholine receptors, synthetic enzymes, and degradative enzymes have been the focus of relatively little empirical investigation. Due to its genetic tractability and anatomical simplicity, the egg laying circuit of the hermaphroditic nematode, Caenorhabditis elegans, is a powerful model system to precisely examine the genetic and molecular targets of cocaine in vivo. Here, we report a novel cocaine-induced behavioral phenotype in C. elegans, cocaine-stimulated egg laying. In addition, we present the results of an in vivo candidate suppression screen of synthetic enzymes, receptors, degradative enzymes, and downstream components of the intracellular signaling cascades of the main neurotransmitter systems that control C. elegans egg laying. Our results show that cocaine-stimulated egg laying is dependent on acetylcholine synthesis and synaptic release, functional nicotinic acetylcholine receptors, and the C. elegans acetylcholinesterases.
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Affiliation(s)
- Soren Emerson
- Neuroscience Interdisciplinary Program, Davidson College, Davidson, NC 28035, USA
| | - Megan Hay
- Biology Department, Davidson College, Davidson, NC 28035, USA
| | - Mark Smith
- Neuroscience Interdisciplinary Program, Davidson College, Davidson, NC 28035, USA
- Psychology Department, Davidson College, Davidson, NC 28035, USA
| | - Ricky Granger
- Biology Department, Davidson College, Davidson, NC 28035, USA
| | - David Blauch
- Chemistry Department, Davidson College, Davidson, NC 28035 USA
| | - Nicole Snyder
- Chemistry Department, Davidson College, Davidson, NC 28035 USA
| | - Rachid El Bejjani
- Neuroscience Interdisciplinary Program, Davidson College, Davidson, NC 28035, USA
- Biology Department, Davidson College, Davidson, NC 28035, USA
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15
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Byrd DT, Jin Y. Wired for insight-recent advances in Caenorhabditis elegans neural circuits. Curr Opin Neurobiol 2021; 69:159-169. [PMID: 33957432 PMCID: PMC8387325 DOI: 10.1016/j.conb.2021.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/16/2021] [Accepted: 02/22/2021] [Indexed: 11/15/2022]
Abstract
The completion of Caenorhabditis elegans connectomics four decades ago has long guided mechanistic investigation of neuronal circuits. Recent technological advances in microscopy and computation programs have aided re-examination of this connectomics, expanding our knowledge by both uncovering previously unreported synaptic connections and also generating models for neural networks underlying behaviors. Combining molecular information from single cell transcriptomes with elegant tools for cell-specific manipulation has further enhanced the ability to precisely investigate individual neurons in behaving animals. This mini-review aims to provide an overview of new information on connectomics and progress toward a molecular atlas of C. elegans nervous system, and discuss emerging findings on neuronal circuits.
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Affiliation(s)
- Dana T Byrd
- Neurobiology Section, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Yishi Jin
- Neurobiology Section, University of California San Diego, La Jolla, CA, 92093, USA; Kavli Institute of Brain and Mind, University of California San Diego, La Jolla, CA, 92093, USA.
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16
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Ravi B, Zhao J, Chaudhry I, Signorelli R, Bartole M, Kopchock RJ, Guijarro C, Kaplan JM, Kang L, Collins KM. Presynaptic Gαo (GOA-1) signals to depress command neuron excitability and allow stretch-dependent modulation of egg laying in Caenorhabditis elegans. Genetics 2021; 218:6284136. [PMID: 34037773 DOI: 10.1093/genetics/iyab080] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 05/18/2021] [Indexed: 12/29/2022] Open
Abstract
Egg laying in the nematode worm Caenorhabditis elegans is a two-state behavior modulated by internal and external sensory input. We have previously shown that homeostatic feedback of embryo accumulation in the uterus regulates bursting activity of the serotonergic HSN command neurons that sustains the egg-laying active state. How sensory feedback of egg release signals to terminate the egg-laying active state is less understood. We find that Gαo, a conserved Pertussis Toxin-sensitive G protein, signals within HSN to inhibit egg-laying circuit activity and prevent entry into the active state. Gαo signaling hyperpolarizes HSN, reducing HSN Ca2+ activity and input onto the postsynaptic vulval muscles. Loss of inhibitory Gαo signaling uncouples presynaptic HSN activity from a postsynaptic, stretch-dependent homeostat, causing precocious entry into the egg-laying active state when only a few eggs are present in the uterus. Feedback of vulval opening and egg release activates the uv1 neuroendocrine cells which release NLP-7 neuropeptides which signal to inhibit egg laying through Gαo-independent mechanisms in the HSNs and Gαo-dependent mechanisms in cells other than the HSNs. Thus, neuropeptide and inhibitory Gαo signaling maintains a bi-stable state of electrical excitability that dynamically controls circuit activity in response to both external and internal sensory input to drive a two-state behavior output.
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Affiliation(s)
- Bhavya Ravi
- Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL USA 33136.,Department of Biology, University of Miami, Coral Gables, FL USA 33146
| | - Jian Zhao
- Department of Neuroscience, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA USA 02114
| | - I Chaudhry
- Department of Biology, University of Miami, Coral Gables, FL USA 33146
| | | | - Mattingly Bartole
- Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL USA 33136.,Department of Biology, University of Miami, Coral Gables, FL USA 33146
| | | | | | - Joshua M Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA USA 02114
| | - Lijun Kang
- Department of Neuroscience, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Kevin M Collins
- Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL USA 33136.,Department of Biology, University of Miami, Coral Gables, FL USA 33146
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