51
|
Marchant JS, Harding WW, Chan JD. Structure-activity profiling of alkaloid natural product pharmacophores against a Schistosoma serotonin receptor. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2018; 8:550-558. [PMID: 30297303 PMCID: PMC6287472 DOI: 10.1016/j.ijpddr.2018.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 12/21/2022]
Abstract
Serotonin (5-HT) is an important regulator of numerous aspects of flatworm biology, ranging from neuromuscular function to sexual maturation and egg laying. In the parasitic blood fluke Schistosoma mansoni, 5-HT targets several G-protein coupled receptors (GPCRs), one of which has been demonstrated to couple to cAMP and regulate parasite movement. This receptor, Sm.5HTRL, has been successfully co-expressed in mammalian cells alongside a luminescent cAMP-biosensor, enabling pharmacological profiling for candidate anti-schistosomal drugs. Here, we have utilized this assay to perform structure-activity investigations of 143 compounds containing previously identified alkaloid natural product pharmacophores (tryptamines, aporphines and protoberberines) shown to regulate Sm.5HTRL. These experiments mapped regions of the tryptamine pharmacophore amenable and intolerant to substitution, highlighting differences relative to orthologous mammalian 5-HT receptors. Potent Sm.5HTRL antagonists were identified, and the efficacy of these compounds were evaluated against live adult parasites cultured ex vivo. Such structure-activity profiling, characterizing the effect of various modifications to these core ring systems on Sm.5HTRL responses, provides greater understanding of pharmacophores selective for this target to aid future drug development efforts. Various alkaloids were screened against a schistosome serotonin receptor, Sm.5HTRL. Compounds with a tryptamine core displayed agonist activity at Sm.5HTRL. Aporphine and protoberberine compounds displayed antagonist activity at Sm.5HTRL. Compound activity at Sm.5HTRL is broadly mirrored by motility effects on adult worms.
Collapse
Affiliation(s)
- Jonathan S Marchant
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, 533226, USA
| | - Wayne W Harding
- Chemistry Department, Hunter College, City University of New York, New York, NY, 10065, USA; Ph.D. Program in Chemistry, CUNY Graduate Center, 365 5th Avenue, New York, NY, 10016, USA; Ph.D. Program in Biochemistry, CUNY Graduate Center, 365 5th Avenue, New York, NY, 10016, USA
| | - John D Chan
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, 533226, USA.
| |
Collapse
|
52
|
Kamireddy K, Chinnu S, Priyanka PS, Rajini PS, Giridhar P. Neuroprotective effect of Decalepis hamiltonii aqueous root extract and purified 2-hydroxy-4-methoxy benzaldehyde on 6-OHDA induced neurotoxicity in Caenorhabditis elegans. Biomed Pharmacother 2018; 105:997-1005. [PMID: 30021395 DOI: 10.1016/j.biopha.2018.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/01/2018] [Accepted: 06/02/2018] [Indexed: 01/01/2023] Open
Abstract
In this study, we investigated the possible neuroprotective efficacy of Decalepis hamiltonii tuber extract against 6-Hydroxy dopamine (6-OHDA) induced neurotoxicity and associated effects in Caenorhabditis elegans. The major component of flavour rich extract from D. hamiltonii is 2-hydroxy-4-methoxy benzaldehyde (2H4MB) which is an isomer of vanillin. We have conducted preliminary experiments with different types of extracts and subsequently DHFE (D. hamiltonii Fresh Tuber Extract) and DHPF (D. hamiltonii purified 2H4MB fraction) were used for further studies. Here we attempted to enumerate the neuroprotective efficacy of the above compounds in worms by evaluating behavioural and mitochondrial function, dopamine content and selective degeneration of dopaminergic neurons in BZ555 strains in comparison with control and 6-OHDA treated organisms. The relative expression levels of selected antioxidant genes involved in defence mechanism like SOD-3, GST-2 and GST-4 were evaluated along with those of CAT-2 and DOP-2 at mRNA level. We observed that both DHPF and DHFE exhibited significant levels of neuroprotective property against 6-OHDA induced neurotoxicity, which was evident in mitochondrial/dopaminergic function and antioxidant defence mechanism.
Collapse
Affiliation(s)
- Kiran Kamireddy
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India
| | - Salim Chinnu
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Food Protectants and Infestation Control Department, CSIR-CFTRI, Mysore, 570020, India
| | - P S Priyanka
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India
| | - P S Rajini
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Food Protectants and Infestation Control Department, CSIR-CFTRI, Mysore, 570020, India
| | - Parvatam Giridhar
- Academy of Scientific and Innovative Research (CSIR-CFTRI Campus), Mysore, India; Plant Cell Biotechnology Department, CSIR-CFTRI, Mysore, 570020, India.
| |
Collapse
|
53
|
Homeostatic Feedback Modulates the Development of Two-State Patterned Activity in a Model Serotonin Motor Circuit in Caenorhabditis elegans. J Neurosci 2018; 38:6283-6298. [PMID: 29891728 DOI: 10.1523/jneurosci.3658-17.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 06/03/2018] [Accepted: 06/06/2018] [Indexed: 01/31/2023] Open
Abstract
Neuron activity accompanies synapse formation and maintenance, but how early circuit activity contributes to behavior development is not well understood. Here, we use the Caenorhabditis elegans egg-laying motor circuit as a model to understand how coordinated cell and circuit activity develops and drives a robust two-state behavior in adults. Using calcium imaging in behaving animals, we find the serotonergic hermaphrodite-specific neurons (HSNs) and vulval muscles show rhythmic calcium transients in L4 larvae before eggs are produced. HSN activity in L4 is tonic and lacks the alternating burst-firing/quiescent pattern seen in egg-laying adults. Vulval muscle activity in L4 is initially uncoordinated but becomes synchronous as the anterior and posterior muscle arms meet at HSN synaptic release sites. However, coordinated muscle activity does not require presynaptic HSN input. Using reversible silencing experiments, we show that neuronal and vulval muscle activity in L4 is not required for the onset of adult behavior. Instead, the accumulation of eggs in the adult uterus renders the muscles sensitive to HSN input. Sterilization or acute electrical silencing of the vulval muscles inhibits presynaptic HSN activity and reversal of muscle silencing triggers a homeostatic increase in HSN activity and egg release that maintains ∼12-15 eggs in the uterus. Feedback of egg accumulation depends upon the vulval muscle postsynaptic terminus, suggesting that a retrograde signal sustains HSN synaptic activity and egg release. Our results show that egg-laying behavior in C. elegans is driven by a homeostat that scales serotonin motor neuron activity in response to postsynaptic muscle feedback.SIGNIFICANCE STATEMENT The functional importance of early, spontaneous neuron activity in synapse and circuit development is not well understood. Here, we show in the nematode Caenorhabditis elegans that the serotonergic hermaphrodite-specific neurons (HSNs) and postsynaptic vulval muscles show activity during circuit development, well before the onset of adult behavior. Surprisingly, early activity is not required for circuit development or the onset of adult behavior and the circuit remains unable to drive egg laying until fertilized embryos are deposited into the uterus. Egg accumulation potentiates vulval muscle excitability, but ultimately acts to promote burst firing in the presynaptic HSNs which results in egg laying. Our results suggest that mechanosensory feedback acts at three distinct steps to initiate, sustain, and terminate C. elegans egg-laying circuit activity and behavior.
Collapse
|
54
|
Barr MM, García LR, Portman DS. Sexual Dimorphism and Sex Differences in Caenorhabditis elegans Neuronal Development and Behavior. Genetics 2018; 208:909-935. [PMID: 29487147 PMCID: PMC5844341 DOI: 10.1534/genetics.117.300294] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/05/2018] [Indexed: 01/05/2023] Open
Abstract
As fundamental features of nearly all animal species, sexual dimorphisms and sex differences have particular relevance for the development and function of the nervous system. The unique advantages of the nematode Caenorhabditis elegans have allowed the neurobiology of sex to be studied at unprecedented scale, linking ultrastructure, molecular genetics, cell biology, development, neural circuit function, and behavior. Sex differences in the C. elegans nervous system encompass prominent anatomical dimorphisms as well as differences in physiology and connectivity. The influence of sex on behavior is just as diverse, with biological sex programming innate sex-specific behaviors and modifying many other aspects of neural circuit function. The study of these differences has provided important insights into mechanisms of neurogenesis, cell fate specification, and differentiation; synaptogenesis and connectivity; principles of circuit function, plasticity, and behavior; social communication; and many other areas of modern neurobiology.
Collapse
Affiliation(s)
- Maureen M Barr
- Department of Genetics, Rutgers University, Piscataway, New Jersey 08854-8082
| | - L Rene García
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, New York 14642
- Department of Neuroscience, University of Rochester, New York 14642
- Department of Biology, University of Rochester, New York 14642
| |
Collapse
|
55
|
Rodríguez-Palero MJ, López-Díaz A, Marsac R, Gomes JE, Olmedo M, Artal-Sanz M. An automated method for the analysis of food intake behaviour in Caenorhabditis elegans. Sci Rep 2018; 8:3633. [PMID: 29483540 PMCID: PMC5832146 DOI: 10.1038/s41598-018-21964-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 02/09/2018] [Indexed: 11/24/2022] Open
Abstract
The study of mechanisms that govern feeding behaviour and its related disorders is a matter of global health interest. The roundworm Caenorhabditis elegans is becoming a model organism of choice to study these conserved pathways. C. elegans feeding depends on the contraction of the pharynx (pumping). Thanks to the worm transparency, pumping can be directly observed under a stereoscope. Therefore, C. elegans feeding has been historically investigated by counting pharyngeal pumping or by other indirect approaches. However, those methods are short-term, time-consuming and unsuitable for independent measurements of sizable numbers of individuals. Although some particular devices and long-term methods have been lately reported, they fail in the automated, scalable and/or continuous aspects. Here we present an automated bioluminescence-based method for the analysis and continuous monitoring of worm feeding in a multi-well format. We validate the method using genetic, environmental and pharmacological modulators of pharyngeal pumping. This flexible methodology allows studying food intake at specific time-points or during longer periods of time, in single worms or in populations at any developmental stage. Additionally, changes in feeding rates in response to differential metabolic status or external environmental cues can be monitored in real time, allowing accurate kinetic measurements.
Collapse
Affiliation(s)
- Mª Jesús Rodríguez-Palero
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas/Junta de Andalucía/Universidad Pablo de Olavide, Departament of Molecular Biology and Biochemical Engineering, Carretera de Utrera, km 1, 41013, Seville, Spain
| | - Ana López-Díaz
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas/Junta de Andalucía/Universidad Pablo de Olavide, Departament of Molecular Biology and Biochemical Engineering, Carretera de Utrera, km 1, 41013, Seville, Spain
| | - Roxane Marsac
- Institut de Biochimie et Génétique Cellulaires - C.N.R.S. UMR 5095 and Université de Bordeaux, 1, rue Camille Saint-Saëns, 33077, Bordeaux Cedex, France
| | - José-Eduardo Gomes
- Institut de Biochimie et Génétique Cellulaires - C.N.R.S. UMR 5095 and Université de Bordeaux, 1, rue Camille Saint-Saëns, 33077, Bordeaux Cedex, France
| | - María Olmedo
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas/Junta de Andalucía/Universidad Pablo de Olavide, Departament of Molecular Biology and Biochemical Engineering, Carretera de Utrera, km 1, 41013, Seville, Spain.
- Department of Genetics, University of Seville, Avenida Reina Mercedes s/n, 41012, Seville, Spain.
| | - Marta Artal-Sanz
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas/Junta de Andalucía/Universidad Pablo de Olavide, Departament of Molecular Biology and Biochemical Engineering, Carretera de Utrera, km 1, 41013, Seville, Spain.
| |
Collapse
|
56
|
Cao J, Packer JS, Ramani V, Cusanovich DA, Huynh C, Daza R, Qiu X, Lee C, Furlan SN, Steemers FJ, Adey A, Waterston RH, Trapnell C, Shendure J. Comprehensive single-cell transcriptional profiling of a multicellular organism. Science 2017; 357:661-667. [PMID: 28818938 DOI: 10.1126/science.aam8940] [Citation(s) in RCA: 826] [Impact Index Per Article: 118.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/12/2017] [Accepted: 07/19/2017] [Indexed: 12/14/2022]
Abstract
To resolve cellular heterogeneity, we developed a combinatorial indexing strategy to profile the transcriptomes of single cells or nuclei, termed sci-RNA-seq (single-cell combinatorial indexing RNA sequencing). We applied sci-RNA-seq to profile nearly 50,000 cells from the nematode Caenorhabditis elegans at the L2 larval stage, which provided >50-fold "shotgun" cellular coverage of its somatic cell composition. From these data, we defined consensus expression profiles for 27 cell types and recovered rare neuronal cell types corresponding to as few as one or two cells in the L2 worm. We integrated these profiles with whole-animal chromatin immunoprecipitation sequencing data to deconvolve the cell type-specific effects of transcription factors. The data generated by sci-RNA-seq constitute a powerful resource for nematode biology and foreshadow similar atlases for other organisms.
Collapse
Affiliation(s)
- Junyue Cao
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Jonathan S Packer
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Vijay Ramani
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | | | - Chau Huynh
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Riza Daza
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Xiaojie Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Scott N Furlan
- Ben Towne Center for Childhood Cancer Research, Seattle Children's Research Institute, Seattle, WA, USA.,Department of Pediatrics, University of Washington, Seattle, WA, USA.,Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - Andrew Adey
- Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, OR, USA.,Knight Cardiovascular Institute, Portland, OR, USA
| | - Robert H Waterston
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA. .,Howard Hughes Medical Institute, Seattle, WA, USA
| |
Collapse
|
57
|
Gracida X, Dion MF, Harris G, Zhang Y, Calarco JA. An Elongin-Cullin-SOCS Box Complex Regulates Stress-Induced Serotonergic Neuromodulation. Cell Rep 2017; 21:3089-3101. [PMID: 29241538 PMCID: PMC6283282 DOI: 10.1016/j.celrep.2017.11.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/15/2017] [Accepted: 11/11/2017] [Indexed: 02/07/2023] Open
Abstract
Neuromodulatory cells transduce environmental information into long-lasting behavioral responses. However, the mechanisms governing how neuronal cells influence behavioral plasticity are difficult to characterize. Here, we adapted the translating ribosome affinity purification (TRAP) approach in C. elegans to profile ribosome-associated mRNAs from three major tissues and the neuromodulatory dopaminergic and serotonergic cells. We identified elc-2, an Elongin C ortholog, specifically expressed in stress-sensing amphid neuron dual ciliated sensory ending (ADF) serotonergic sensory neurons, and we found that it plays a role in mediating a long-lasting change in serotonin-dependent feeding behavior induced by heat stress. We demonstrate that ELC-2 and the von Hippel-Lindau protein VHL-1, components of an Elongin-Cullin-SOCS box (ECS) E3 ubiquitin ligase, modulate this behavior after experiencing stress. Also, heat stress induces a transient redistribution of ELC-2, becoming more nuclearly enriched. Together, our results demonstrate dynamic regulation of an E3 ligase and a role for an ECS complex in neuromodulation and control of lasting behavioral states.
Collapse
Affiliation(s)
- Xicotencatl Gracida
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Michael F Dion
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Gareth Harris
- Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Yun Zhang
- Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
| | - John A Calarco
- FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA; Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
| |
Collapse
|
58
|
Fatin SN, Boon-Khai T, Shu-Chien AC, Khairuddean M, Al-Ashraf Abdullah A. A Marine Actinomycete Rescues Caenorhabditis elegans from Pseudomonas aeruginosa Infection through Restitution of Lysozyme 7. Front Microbiol 2017; 8:2267. [PMID: 29201023 PMCID: PMC5696594 DOI: 10.3389/fmicb.2017.02267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 11/03/2017] [Indexed: 11/13/2022] Open
Abstract
The resistance of Pseudomonas aeruginosa to conventional antimicrobial treatment is a major scourge in healthcare. Therefore, it is crucial that novel potent anti-infectives are discovered. The aim of the present study is to screen marine actinomycetes for chemical entities capable of overcoming P. aeruginosa infection through mechanisms involving anti-virulence or host immunity activities. A total of 18 actinomycetes isolates were sampled from marine sediment of Songsong Island, Kedah, Malaysia. Upon confirming that the methanolic crude extract of these isolates do not display direct bactericidal activities, they were tested for capacity to rescue Caenorhabditis elegans infected with P. aeruginosa strain PA14. A hexane partition of the extract from one isolate, designated as Streptomyces sp. CCB-PSK207, could promote the survival of PA14 infected worms by more than 60%. Partial 16S sequence analysis on this isolate showed identity of 99.79% with Streptomyces sundarbansensis. This partition did not impair feeding behavior of C. elegans worms. Tested on PA14, the partition also did not affect bacterial growth or its ability to colonize host gut. The production of biofilm, protease, and pyocyanin in PA14 were uninterrupted, although there was an increase in elastase production. In lys-7::GFP worms, this partition was shown to induce the expression of lysozyme 7, an important innate immunity defense molecule that was repressed during PA14 infection. GC-MS analysis of the bioactive fraction of Streptomyces sp. CCB-PSK207 revealed the presence of methyl esters of branched saturated fatty acids. In conclusion, this is the first report of a marine actinomycete producing metabolites capable of rescuing C. elegans from PA14 through a lys-7 mediated activity.
Collapse
Affiliation(s)
- Siti N. Fatin
- Centre for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas, Malaysia
| | - Tan Boon-Khai
- Centre for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas, Malaysia
| | - Alexander Chong Shu-Chien
- Centre for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas, Malaysia
- Malaysian Institute of Pharmaceuticals and Nutraceuticals (IPHARM), National Institute of Biotechnology Malaysia, Ministry of Science, Technology and Innovation, Bukit Gambir, Malaysia
- School of Biological Sciences, Universiti Sains Malaysia, Minden, Malaysia
| | - Melati Khairuddean
- School of Chemical Sciences, Universiti Sains Malaysia, Minden, Malaysia
| | - Amirul Al-Ashraf Abdullah
- Centre for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas, Malaysia
- Malaysian Institute of Pharmaceuticals and Nutraceuticals (IPHARM), National Institute of Biotechnology Malaysia, Ministry of Science, Technology and Innovation, Bukit Gambir, Malaysia
- School of Biological Sciences, Universiti Sains Malaysia, Minden, Malaysia
| |
Collapse
|
59
|
Sanders J, Scholz M, Merutka I, Biron D. Distinct unfolded protein responses mitigate or mediate effects of nonlethal deprivation of C. elegans sleep in different tissues. BMC Biol 2017; 15:67. [PMID: 28844202 PMCID: PMC5572162 DOI: 10.1186/s12915-017-0407-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/24/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Disrupting sleep during development leads to lasting deficits in chordates and arthropods. To address lasting impacts of sleep deprivation in Caenorhabditis elegans, we established a nonlethal deprivation protocol. RESULTS Deprivation triggered protective insulin-like signaling and two unfolded protein responses (UPRs): the mitochondrial (UPRmt) and the endoplasmic reticulum (UPRER) responses. While the latter is known to be triggered by sleep deprivation in rodent and insect brains, the former was not strongly associated with sleep deprivation previously. We show that deprivation results in a feeding defect when the UPRmt is deficient and in UPRER-dependent germ cell apoptosis. In addition, when the UPRER is deficient, deprivation causes excess twitching in vulval muscles, mirroring a trend caused by loss of egg-laying command neurons. CONCLUSIONS These data show that nonlethal deprivation of C. elegans sleep causes proteotoxic stress. Unless mitigated, distinct types of deprivation-induced proteotoxicity can lead to anatomically and genetically separable lasting defects. The relative importance of different UPRs post-deprivation likely reflects functional, developmental, and genetic differences between the respective tissues and circuits.
Collapse
Affiliation(s)
- Jarred Sanders
- Genetics, Genomics, and Systems Biology, The University of Chicago, Chicago, IL, 60637, USA.
| | - Monika Scholz
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - Ilaria Merutka
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA
| | - David Biron
- Genetics, Genomics, and Systems Biology, The University of Chicago, Chicago, IL, 60637, USA.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, 60637, USA.,Department of Physics, The University of Chicago, Chicago, IL, 60637, USA
| |
Collapse
|
60
|
Cao J, Packer JS, Ramani V, Cusanovich DA, Huynh C, Daza R, Qiu X, Lee C, Furlan SN, Steemers FJ, Adey A, Waterston RH, Trapnell C, Shendure J. Comprehensive single-cell transcriptional profiling of a multicellular organism. Science 2017. [DOI: 10.1126/science.aam8940 order by 10746--] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Junyue Cao
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Jonathan S. Packer
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Vijay Ramani
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | | | - Chau Huynh
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Riza Daza
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Xiaojie Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Scott N. Furlan
- Ben Towne Center for Childhood Cancer Research, Seattle Children’s Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - Andrew Adey
- Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, OR, USA
- Knight Cardiovascular Institute, Portland, OR, USA
| | | | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, Seattle, WA, USA
| |
Collapse
|
61
|
Wang J, Luo J, Aryal DK, Wetsel WC, Nass R, Benovic JL. G protein-coupled receptor kinase-2 (GRK-2) regulates serotonin metabolism through the monoamine oxidase AMX-2 in Caenorhabditis elegans. J Biol Chem 2017; 292:5943-5956. [PMID: 28213524 DOI: 10.1074/jbc.m116.760850] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 02/15/2017] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) regulate many animal behaviors. GPCR signaling is mediated by agonist-promoted interactions of GPCRs with heterotrimeric G proteins, GPCR kinases (GRKs), and arrestins. To further elucidate the role of GRKs in regulating GPCR-mediated behaviors, we utilized the genetic model system Caenorhabditis elegans Our studies demonstrate that grk-2 loss-of-function strains are egg laying-defective and contain low levels of serotonin (5-HT) and high levels of the 5-HT metabolite 5-hydroxyindole acetic acid (5-HIAA). The egg laying defect could be rescued by the expression of wild type but not by catalytically inactive grk-2 or by the selective expression of grk-2 in hermaphrodite-specific neurons. The addition of 5-HT or inhibition of 5-HT metabolism also rescued the egg laying defect. Furthermore, we demonstrate that AMX-2 is the primary monoamine oxidase that metabolizes 5-HT in C. elegans, and we also found that grk-2 loss-of-function strains have abnormally high levels of AMX-2 compared with wild-type nematodes. Interestingly, GRK-2 was also found to interact with and promote the phosphorylation of AMX-2. Additional studies reveal that 5-HIAA functions to inhibit egg laying in a manner dependent on the 5-HT receptor SER-1 and the G protein GOA-1. These results demonstrate that GRK-2 modulates 5-HT metabolism by regulating AMX-2 function and that 5-HIAA may function in the SER-1 signaling pathway.
Collapse
Affiliation(s)
- Jianjun Wang
- From the Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Jiansong Luo
- From the Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | | | - William C Wetsel
- Departments of Psychiatry and Behavioral Sciences.,Cell Biology, and.,Neurobiology and.,Mouse Behavioral and Neuroendocrine Analysis Core Facility, Duke University Medical Center, Durham, North Carolina 27710, and
| | - Richard Nass
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Jeffrey L Benovic
- From the Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107,
| |
Collapse
|
62
|
Lee KS, Iwanir S, Kopito RB, Scholz M, Calarco JA, Biron D, Levine E. Serotonin-dependent kinetics of feeding bursts underlie a graded response to food availability in C. elegans. Nat Commun 2017; 8:14221. [PMID: 28145493 PMCID: PMC5296638 DOI: 10.1038/ncomms14221] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 12/08/2016] [Indexed: 11/16/2022] Open
Abstract
Animals integrate physiological and environmental signals to modulate their food uptake. The nematode C. elegans, whose food uptake consists of pumping bacteria from the environment into the gut, provides excellent opportunities for discovering principles of conserved regulatory mechanisms. Here we show that worms implement a graded feeding response to the concentration of environmental bacteria by modulating a commitment to bursts of fast pumping. Using long-term, high-resolution, longitudinal recordings of feeding dynamics under defined conditions, we find that the frequency and duration of pumping bursts increase and the duration of long pauses diminishes in environments richer in bacteria. The bioamine serotonin is required for food-dependent induction of bursts as well as for maintaining their high rate of pumping through two distinct mechanisms. We identify the differential roles of distinct families of serotonin receptors in this process and propose that regulation of bursts is a conserved mechanism of behaviour and motor control.
Collapse
Affiliation(s)
- Kyung Suk Lee
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Shachar Iwanir
- Department of Physics and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Ronen B. Kopito
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Monika Scholz
- Department of Physics and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - John A. Calarco
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - David Biron
- Department of Physics and the James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
- The Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Erel Levine
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- FAS Center for Systems Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| |
Collapse
|
63
|
Collins KM, Bode A, Fernandez RW, Tanis JE, Brewer JC, Creamer MS, Koelle MR. Activity of the C. elegans egg-laying behavior circuit is controlled by competing activation and feedback inhibition. eLife 2016; 5. [PMID: 27849154 PMCID: PMC5142809 DOI: 10.7554/elife.21126] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/14/2016] [Indexed: 01/13/2023] Open
Abstract
Like many behaviors, Caenorhabditis elegans egg laying alternates between inactive and active states. To understand how the underlying neural circuit turns the behavior on and off, we optically recorded circuit activity in behaving animals while manipulating circuit function using mutations, optogenetics, and drugs. In the active state, the circuit shows rhythmic activity phased with the body bends of locomotion. The serotonergic HSN command neurons initiate the active state, but accumulation of unlaid eggs also promotes the active state independent of the HSNs. The cholinergic VC motor neurons slow locomotion during egg-laying muscle contraction and egg release. The uv1 neuroendocrine cells mechanically sense passage of eggs through the vulva and release tyramine to inhibit egg laying, in part via the LGC-55 tyramine-gated Cl- channel on the HSNs. Our results identify discrete signals that entrain or detach the circuit from the locomotion central pattern generator to produce active and inactive states. DOI:http://dx.doi.org/10.7554/eLife.21126.001 It has been said that if the human brain were so simple that we could understand it, we would be so simple that we couldn’t. This quote neatly captures the challenge of working out how 80 billion neurons collectively generate our thoughts and behavior. Fortunately, the nervous system is also organized into simpler units called circuits. Each consists of a relatively small number of neurons, which communicate with one another to control as little as a single behavior. These circuits should in principle be simple enough for us to understand, particularly if we study them in nervous systems less complex than our own. Despite this, there is currently not a single circuit in any organism in which we can explain how communication between individual neurons generates behavior. Collins et al. therefore set out to characterize a simple neural circuit in one of the simplest model organisms: the egg-laying circuit of the worm C. elegans. Using mutations, drugs and molecular genetic techniques, Collins et al. systematically altered the activity and signaling of each of the neurons within the egg-laying circuit. The experiments revealed that cells called command neurons trigger egg laying by producing signals that switch on the rest of the circuit. Once activated, the circuit is able to respond to waves of activity from a second circuit – called the central pattern generator – that also controls the worm’s movement. Finally, laying an egg activates a third set of neurons, which release a signal that returns the circuit to its inactive state. The use of distinct signals and neurons to activate the circuit, to coordinate its ongoing activity, and to inactivate the circuit when its task is complete also applies to many other neural circuits. Now that these signals have been identified in one circuit, it should be possible to build on these findings to better understand how others work. DOI:http://dx.doi.org/10.7554/eLife.21126.002
Collapse
Affiliation(s)
- Kevin M Collins
- Department of Biology, University of Miami, Coral Gables, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Addys Bode
- Department of Biology, University of Miami, Coral Gables, United States
| | - Robert W Fernandez
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Jessica E Tanis
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Jacob C Brewer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Matthew S Creamer
- Interdepartmental Neuroscience Program, Yale University, New Haven, United States
| | - Michael R Koelle
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.,Interdepartmental Neuroscience Program, Yale University, New Haven, United States
| |
Collapse
|
64
|
Scholz M, Lynch DJ, Lee KS, Levine E, Biron D. A scalable method for automatically measuring pharyngeal pumping in C. elegans. J Neurosci Methods 2016; 274:172-178. [PMID: 27474347 DOI: 10.1016/j.jneumeth.2016.07.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 07/21/2016] [Accepted: 07/22/2016] [Indexed: 11/20/2022]
Abstract
BACKGROUND The nematode Caenorhabditis elegans is widely used for studying small neural circuits underlying behavior. In particular, the rhythmic feeding motions collectively termed pharyngeal pumping are regulated by a nearly autonomous network of 20 neurons of 14 types. Despite much progress achieved through laser ablation, genetics, electrophysiology, and optogenetics, key questions regarding the regulation of pumping remain open. NEW METHOD We describe the implementation and application of a scalable automated method for measuring pumping in controlled environments. Our implementation is affordable and flexible: key hardware and software elements can be modified to accommodate different requirements. RESULTS We demonstrate prolonged measurements under controlled conditions and the resulting high quality data. We show the scalability of our method, enabling high throughput, and its suitability for maintaining static and dynamic conditions. When food availability was oscillated, pumping rates were low as compared to steady conditions and pumping activity was not reliably modulated in response to changes in food concentration. COMPARISON WITH EXISTING METHOD The prevailing method for measuring rates of pumping relies on scoring by visual inspection of short recordings. Our automated method compares well with manual scoring. It enables detailed statistical characterization under experimental conditions not previously accessible and minimizes unintentional bias. CONCLUSIONS Our approach adds a powerful tool for studying pharyngeal pumping. It enhances the experimental versatility of assaying genetic and pharmacological manipulations and the ability to characterize the resulting behavior. Both the experimental setup and the analysis can be readily adapted to additional challenging motion detection problems.
Collapse
Affiliation(s)
- Monika Scholz
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Dylan J Lynch
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Kyung Suk Lee
- Department of Physics and Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Erel Levine
- Department of Physics and Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - David Biron
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA; Department of Physics, The University of Chicago, Chicago, IL 60637, USA.
| |
Collapse
|
65
|
Pharmacological profiling an abundantly expressed schistosome serotonergic GPCR identifies nuciferine as a potent antagonist. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2016; 6:364-370. [PMID: 27397763 PMCID: PMC5196489 DOI: 10.1016/j.ijpddr.2016.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 06/20/2016] [Indexed: 12/22/2022]
Abstract
5-hydroxytryptamine (5-HT) is a key regulator of muscle contraction in parasitic flatworms. In Schistosoma mansoni, the myoexcitatory action of 5-HT is effected through activation of a serotonergic GPCR (Sm.5HTRL), prioritizing pharmacological characterization of this target for anthelmintic drug discovery. Here, we have examined the effects of several aporphine alkaloids on the signaling activity of a heterologously expressed Sm.5HTRL construct using a cAMP biosensor assay. Four structurally related natural products - nuciferine, D-glaucine, boldine and bulbocapnine - were demonstrated to block Sm.5HTRL evoked cAMP generation with the potency of GPCR blockade correlating well with the ability of each drug to inhibit contractility of schistosomule larvae. Nuciferine was also effective at inhibiting both basal and 5-HT evoked motility of adult schistosomes. These data advance our understanding of structure-affinity relationships at Sm.5HTRL, and demonstrate the effectiveness of Sm.5HTRL antagonists as hypomotility-evoking drugs across different parasite life cycle stages.
Collapse
|
66
|
Abstract
Electrophysiological recordings have enabled identification of physiologically distinct yet behaviorally similar states of mammalian sleep. In contrast, sleep in nonmammals has generally been identified behaviorally and therefore regarded as a physiologically uniform state characterized by quiescence of feeding and locomotion, reduced responsiveness, and rapid reversibility. The nematode Caenorhabditis elegans displays sleep-like quiescent behavior under two conditions: developmentally timed quiescence (DTQ) occurs during larval transitions, and stress-induced quiescence (SIQ) occurs in response to exposure to cellular stressors. Behaviorally, DTQ and SIQ appear identical. Here, we use optogenetic manipulations of neuronal and muscular activity, pharmacology, and genetic perturbations to uncover circuit and molecular mechanisms of DTQ and SIQ. We find that locomotion quiescence induced by DTQ- and SIQ-associated neuropeptides occurs via their action on the nervous system, although their neuronal target(s) and/or molecular mechanisms likely differ. Feeding quiescence during DTQ results from a loss of pharyngeal muscle excitability, whereas feeding quiescence during SIQ results from a loss of excitability in the nervous system. Together these results indicate that, as in mammals, quiescence is subserved by different mechanisms during distinct sleep-like states in C. elegans.
Collapse
|
67
|
Dancy BM, Brockway N, Ramadasan-Nair R, Yang Y, Sedensky MM, Morgan PG. Glutathione S-transferase mediates an ageing response to mitochondrial dysfunction. Mech Ageing Dev 2015; 153:14-21. [PMID: 26704446 DOI: 10.1016/j.mad.2015.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 12/03/2015] [Accepted: 12/10/2015] [Indexed: 12/30/2022]
Abstract
To understand primary mitochondrial disease, we utilized a complex I-deficient Caenorhabditis elegans mutant, gas-1. These animals strongly upregulate the expression of gst-14 (encoding a glutathione S-transferase). Knockdown of gst-14 dramatically extends the lifespan of gas-1 and increases hydroxynonenal (HNE) modified mitochondrial proteins without improving complex I function. We observed no change in reactive oxygen species levels as measured by Mitosox staining, consistent with a potential role of GST-14 in HNE clearance. The upregulation of gst-14 in gas-1 animals is specific to the pharynx. These data suggest that an HNE-mediated response in the pharynx could be beneficial for lifespan extension in the context of complex I dysfunction in C. elegans. Thus, whereas HNE is typically considered damaging, our work is consistent with recent reports of its role in signaling, and that in this case, the signal is pro-longevity in a model of mitochondrial dysfunction.
Collapse
Affiliation(s)
- Beverley M Dancy
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Nicole Brockway
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Renjini Ramadasan-Nair
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Yoing Yang
- Department of Genetics, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195, USA.
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195, USA.
| |
Collapse
|
68
|
Zhou Y, Falck JR, Rothe M, Schunck WH, Menzel R. Role of CYP eicosanoids in the regulation of pharyngeal pumping and food uptake in Caenorhabditis elegans. J Lipid Res 2015; 56:2110-23. [PMID: 26399467 PMCID: PMC4617398 DOI: 10.1194/jlr.m061887] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/15/2015] [Indexed: 11/20/2022] Open
Abstract
Cytochrome P450 (CYP)-dependent eicosanoids comprise epoxy- and hydroxy-metabolites of long-chain PUFAs (LC-PUFAs). In mammals, CYP eicosanoids contribute to the regulation of cardiovascular and renal function. Caenorhabditis elegans produces a large set of CYP eicosanoids; however, their role in worm's physiology is widely unknown. Mutant strains deficient in LC-PUFA/eicosanoid biosynthesis displayed reduced pharyngeal pumping frequencies. This impairment was rescued by long-term eicosapentaenoic and/or arachidonic acid supplementation, but not with a nonmetabolizable LC-PUFA analog. Short-term treatment with 17,18-epoxyeicosatetraenoic acid (17,18-EEQ), the most abundant CYP eicosanoid in C. elegans, was as effective as long-term LC-PUFA supplementation in the mutant strains. In contrast, 20-HETE caused decreased pumping frequencies. The opposite effects of 17,18-EEQ and 20-HETE were mirrored by the actions of neurohormones. 17,18-EEQ mimicked the stimulating effect of serotonin when added to starved worms, whereas 20-HETE shared the inhibitory effect of octopamine in the presence of abundant food. In wild-type worms, serotonin increased free 17,18-EEQ levels, whereas octopamine selectively induced the synthesis of hydroxy-metabolites. These results suggest that CYP eicosanoids may serve as second messengers in the regulation of pharyngeal pumping and food uptake in C. elegans.
Collapse
Affiliation(s)
- Yiwen Zhou
- Department of Biology, Ecology, Humboldt University of Berlin, 10115 Berlin, Germany
| | - John R. Falck
- Department of Biochemistry, University of Texas Southwestern, Dallas, TX 75390
| | | | | | - Ralph Menzel
- Department of Biology, Ecology, Humboldt University of Berlin, 10115 Berlin, Germany
| |
Collapse
|
69
|
Dallière N, Bhatla N, Luedtke Z, Ma DK, Woolman J, Walker RJ, Holden-Dye L, O'Connor V. Multiple excitatory and inhibitory neural signals converge to fine-tune Caenorhabditis elegans feeding to food availability. FASEB J 2015; 30:836-48. [PMID: 26514165 DOI: 10.1096/fj.15-279257] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/13/2015] [Indexed: 01/02/2023]
Abstract
How an animal matches feeding to food availability is a key question for energy homeostasis. We addressed this in the nematode Caenorhabditis elegans, which couples feeding to the presence of its food (bacteria) by regulating pharyngeal activity (pumping). We scored pumping in the presence of food and over an extended time course of food deprivation in wild-type and mutant worms to determine the neural substrates of adaptive behavior. Removal of food initially suppressed pumping but after 2 h this was accompanied by intermittent periods of high activity. We show pumping is fine-tuned by context-specific neural mechanisms and highlight a key role for inhibitory glutamatergic and excitatory cholinergic/peptidergic drives in the absence of food. Additionally, the synaptic protein UNC-31 [calcium-activated protein for secretion (CAPS)] acts through an inhibitory pathway not explained by previously identified contributions of UNC-31/CAPS to neuropeptide or glutamate transmission. Pumping was unaffected by laser ablation of connectivity between the pharyngeal and central nervous system indicating signals are either humoral or intrinsic to the enteric system. This framework in which control is mediated through finely tuned excitatory and inhibitory drives resonates with mammalian hypothalamic control of feeding and suggests that fundamental regulation of this basic animal behavior may be conserved through evolution from nematode to human.
Collapse
Affiliation(s)
- Nicolas Dallière
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Nikhil Bhatla
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Zara Luedtke
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Dengke K Ma
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jonathan Woolman
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Robert J Walker
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lindy Holden-Dye
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Vincent O'Connor
- *Centre for Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, United Kingdom; and Howard Hughes Medical Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| |
Collapse
|
70
|
Abstract
The compact nervous system of Caenorhabditis elegans and its genetic tractability are features that make this organism highly suitable for investigating energy balance in an animal system. Here, we focus on molecular components and organizational principles emerging from the investigation of pathways that largely originate in the nervous system and regulate feeding behavior but also peripheral fat regulation through neuroendocrine signaling. We provide an overview of studies aimed at understanding how C. elegans integrate internal and external cues in feeding behavior. We highlight some of the similarities and differences in energy balance between C. elegans and mammals. We also provide our perspective on unresolved issues, both conceptual and technical, that we believe have hampered critical evaluation of findings relevant to fat regulation in C. elegans.
Collapse
Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California, San Francisco, California 94158;
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, California 94158;
| |
Collapse
|
71
|
Cheong MC, Artyukhin AB, You YJ, Avery L. An opioid-like system regulating feeding behavior in C. elegans. eLife 2015; 4. [PMID: 25898004 PMCID: PMC4427864 DOI: 10.7554/elife.06683] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 04/21/2015] [Indexed: 01/29/2023] Open
Abstract
Neuropeptides are essential for the regulation of appetite. Here we show that neuropeptides could regulate feeding in mutants that lack neurotransmission from the motor neurons that stimulate feeding muscles. We identified nlp-24 by an RNAi screen of 115 neuropeptide genes, testing whether they affected growth. NLP-24 peptides have a conserved YGGXX sequence, similar to mammalian opioid neuropeptides. In addition, morphine and naloxone respectively stimulated and inhibited feeding in starved worms, but not in worms lacking NPR-17, which encodes a protein with sequence similarity to opioid receptors. Opioid agonists activated heterologously expressed NPR-17, as did at least one NLP-24 peptide. Worms lacking the ASI neurons, which express npr-17, did not response to naloxone. Thus, we suggest that Caenorhabditis elegans has an endogenous opioid system that acts through NPR-17, and that opioids regulate feeding via ASI neurons. Together, these results suggest C. elegans may be the first genetically tractable invertebrate opioid model. DOI:http://dx.doi.org/10.7554/eLife.06683.001 When and how much an animal eats is controlled by a complex web of signals that are produced by the animal's body and brain. Molecules called opioid neuropeptides are among these signals, and act to control eating in mammals by binding to receptors in the brain and body. These receptors can also bind to similar molecules called opiates (such as morphine); opiates are amongst the oldest drugs used by humans and have diverse effects ranging from pain relief to addiction. While the activities of opiates and opioid neuropeptides have been studied in mammals, relatively little is known about opioid signaling in simpler animals. The mechanisms behind many biological processes have been investigated using a worm called C. elegans as a model system because it has a simple body plan and its genes can be altered easily. The feeding behavior of C. elegans is no exception. This worm feeds by contracting and relaxing its pharyngeal muscle to move food into its gut. When the worms sense that food is available, this ‘pharyngeal pumping’ is regulated by one type of nerve cell. Slow pharyngeal pumping also continues in starved worms when food is not available, possibly to encourage them to eat new potential sources of food. However, this slow pumping does not require the same type of nerve cell. Cheong et al. hypothesized that the slow pumping in starved worms might depend on neuropeptide signaling instead, and have now tested this idea using engineered worms that made lower levels of a number of these molecules. The experiments uncovered a molecule called NLP-24 that promotes the slow pharyngeal pumping. This molecule is similar to opioid neuropeptides found in mammals. Worms that made less NLP-24 than normal grew more slowly; this suggests that they had problems feeding. Moreover, the levels of NLP-24 were found to increase in normal worms soon after they were deprived of food. Further experiments revealed the identity of the receptor for this molecule, which is also similar to mammalian opioid receptors. The discovery that opioid signaling is involved in C. elegans' feeding behavior may well, in future, also help to identify new molecular players involved in opioid signaling. Further studies might also help the search for ways to reduce the problematic side-effects that limit the usefulness of opiate drugs as medicines. DOI:http://dx.doi.org/10.7554/eLife.06683.002
Collapse
Affiliation(s)
- Mi Cheong Cheong
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States
| | - Alexander B Artyukhin
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States
| | - Young-Jai You
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, United States
| | - Leon Avery
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States
| |
Collapse
|
72
|
Measuring Food Intake and Nutrient Absorption in Caenorhabditis elegans. Genetics 2015; 200:443-54. [PMID: 25903497 PMCID: PMC4492371 DOI: 10.1534/genetics.115.175851] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 04/16/2015] [Indexed: 12/19/2022] Open
Abstract
Caenorhabditiselegans has emerged as a powerful model to study the genetics of feeding, food-related behaviors, and metabolism. Despite the many advantages of C. elegans as a model organism, direct measurement of its bacterial food intake remains challenging. Here, we describe two complementary methods that measure the food intake of C. elegans. The first method is a microtiter plate-based bacterial clearing assay that measures food intake by quantifying the change in the optical density of bacteria over time. The second method, termed pulse feeding, measures the absorption of food by tracking de novo protein synthesis using a novel metabolic pulse-labeling strategy. Using the bacterial clearance assay, we compare the bacterial food intake of various C. elegans strains and show that long-lived eat mutants eat substantially more than previous estimates. To demonstrate the applicability of the pulse-feeding assay, we compare the assimilation of food for two C. elegans strains in response to serotonin. We show that serotonin-increased feeding leads to increased protein synthesis in a SER-7-dependent manner, including proteins known to promote aging. Protein content in the food has recently emerged as critical factor in determining how food composition affects aging and health. The pulse-feeding assay, by measuring de novo protein synthesis, represents an ideal method to unequivocally establish how the composition of food dictates protein synthesis. In combination, these two assays provide new and powerful tools for C. elegans research to investigate feeding and how food intake affects the proteome and thus the physiology and health of an organism.
Collapse
|
73
|
Law W, Wuescher LM, Ortega A, Hapiak VM, Komuniecki PR, Komuniecki R. Heterologous Expression in Remodeled C. elegans: A Platform for Monoaminergic Agonist Identification and Anthelmintic Screening. PLoS Pathog 2015; 11:e1004794. [PMID: 25928899 PMCID: PMC4415803 DOI: 10.1371/journal.ppat.1004794] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 03/09/2015] [Indexed: 11/30/2022] Open
Abstract
Monoamines, such as 5-HT and tyramine (TA), paralyze both free-living and parasitic nematodes when applied exogenously and serotonergic agonists have been used to clear Haemonchus contortus infections in vivo. Since nematode cell lines are not available and animal screening options are limited, we have developed a screening platform to identify monoamine receptor agonists. Key receptors were expressed heterologously in chimeric, genetically-engineered Caenorhabditis elegans, at sites likely to yield robust phenotypes upon agonist stimulation. This approach potentially preserves the unique pharmacologies of the receptors, while including nematode-specific accessory proteins and the nematode cuticle. Importantly, the sensitivity of monoamine-dependent paralysis could be increased dramatically by hypotonic incubation or the use of bus mutants with increased cuticular permeabilities. We have demonstrated that the monoamine-dependent inhibition of key interneurons, cholinergic motor neurons or body wall muscle inhibited locomotion and caused paralysis. Specifically, 5-HT paralyzed C. elegans 5-HT receptor null animals expressing either nematode, insect or human orthologues of a key Gαo-coupled 5-HT1-like receptor in the cholinergic motor neurons. Importantly, 8-OH-DPAT and PAPP, 5-HT receptor agonists, differentially paralyzed the transgenic animals, with 8-OH-DPAT paralyzing mutant animals expressing the human receptor at concentrations well below those affecting its C. elegans or insect orthologues. Similarly, 5-HT and TA paralyzed C. elegans 5-HT or TA receptor null animals, respectively, expressing either C. elegans or H. contortus 5-HT or TA-gated Cl- channels in either C. elegans cholinergic motor neurons or body wall muscles. Together, these data suggest that this heterologous, ectopic expression screening approach will be useful for the identification of agonists for key monoamine receptors from parasites and could have broad application for the identification of ligands for a host of potential anthelmintic targets.
Collapse
Affiliation(s)
- Wenjing Law
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, United States of America
| | - Leah M. Wuescher
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, United States of America
| | - Amanda Ortega
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, United States of America
| | - Vera M. Hapiak
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, United States of America
| | - Patricia R. Komuniecki
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, United States of America
| | - Richard Komuniecki
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, United States of America
| |
Collapse
|
74
|
Zhang L, Gualberto DG, Guo X, Correa P, Jee C, Garcia LR. TMC-1 attenuates C. elegans development and sexual behaviour in a chemically defined food environment. Nat Commun 2015; 6:6345. [PMID: 25695879 DOI: 10.1038/ncomms7345] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 01/21/2015] [Indexed: 01/22/2023] Open
Abstract
Although diet affects growth and behaviour, the adaptive mechanisms that coordinate these processes in non-optimal food sources are unclear. Here we show that the C. elegans tmc-1 channel, which is homologous to the mammalian tmc deafness genes, attenuates development and inhibits sexual behaviour in non-optimal food, the synthetic CeMM medium. In CeMM medium, signalling from the pharyngeal MC neurons and body wall muscles slows larval development. However, in the non-standard diet, mutation in tmc-1 accelerates development, by impairing the excitability of these cells. The tmc-1 larva can immediately generate ATP when fed CeMM, and their fast development requires insulin signalling. Our findings suggest that the tmc-1 channel indirectly affects metabolism in wild-type animals. In addition to regulating the development, we show that mutating tmc-1 can relax diet-induced inhibition of male sexual behaviour, thus indicating that a single regulator can be genetically modified to promote growth rate and reproductive success in new environments.
Collapse
Affiliation(s)
- Liusuo Zhang
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Daisy G Gualberto
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Xiaoyan Guo
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Paola Correa
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - Changhoon Jee
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| | - L Rene Garcia
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU College Station, Texas 77843-3258, USA
| |
Collapse
|
75
|
Cunningham KA, Bouagnon AD, Barros AG, Lin L, Malard L, Romano-Silva MA, Ashrafi K. Loss of a neural AMP-activated kinase mimics the effects of elevated serotonin on fat, movement, and hormonal secretions. PLoS Genet 2014; 10:e1004394. [PMID: 24921650 PMCID: PMC4055570 DOI: 10.1371/journal.pgen.1004394] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 04/07/2014] [Indexed: 12/30/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an evolutionarily conserved master regulator of metabolism and a therapeutic target in type 2 diabetes. As an energy sensor, AMPK activity is responsive to both metabolic inputs, for instance the ratio of AMP to ATP, and numerous hormonal cues. As in mammals, each of two genes, aak-1 and aak-2, encode for the catalytic subunit of AMPK in C. elegans. Here we show that in C. elegans loss of aak-2 mimics the effects of elevated serotonin signaling on fat reduction, slowed movement, and promoting exit from dauer arrest. Reconstitution of aak-2 in only the nervous system restored wild type fat levels and movement rate to aak-2 mutants and reconstitution in only the ASI neurons was sufficient to significantly restore dauer maintenance to the mutant animals. As in elevated serotonin signaling, inactivation of AAK-2 in the ASI neurons caused enhanced secretion of dense core vesicles from these neurons. The ASI neurons are the site of production of the DAF-7 TGF-β ligand and the DAF-28 insulin, both of which are secreted by dense core vesicles and play critical roles in whether animals stay in dauer or undergo reproductive development. These findings show that elevated levels of serotonin promote enhanced secretions of systemic regulators of pro-growth and differentiation pathways through inactivation of AAK-2. As such, AMPK is not only a recipient of hormonal signals but can also be an upstream regulator. Our data suggest that some of the physiological phenotypes previously attributed to peripheral AAK-2 activity on metabolic targets may instead be due to the role of this kinase in neural serotonin signaling.
Collapse
Affiliation(s)
- Katherine A. Cunningham
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Aude D. Bouagnon
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Alexandre G. Barros
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Lin Lin
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Leandro Malard
- Departamento de Física, Instituto de Ciências Exatas da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Marco Aurélio Romano-Silva
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
| |
Collapse
|
76
|
Trojanowski NF, Padovan-Merhar O, Raizen DM, Fang-Yen C. Neural and genetic degeneracy underlies Caenorhabditis elegans feeding behavior. J Neurophysiol 2014; 112:951-61. [PMID: 24872529 DOI: 10.1152/jn.00150.2014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Degenerate networks, in which structurally distinct elements can perform the same function or yield the same output, are ubiquitous in biology. Degeneracy contributes to the robustness and adaptability of networks in varied environmental and evolutionary contexts. However, how degenerate neural networks regulate behavior in vivo is poorly understood, especially at the genetic level. Here, we identify degenerate neural and genetic mechanisms that underlie excitation of the pharynx (feeding organ) in the nematode Caenorhabditis elegans using cell-specific optogenetic excitation and inhibition. We show that the pharyngeal neurons MC, M2, M4, and I1 form multiple direct and indirect excitatory pathways in a robust network for control of pharyngeal pumping. I1 excites pumping via MC and M2 in a state-dependent manner. We identify nicotinic and muscarinic receptors through which the pharyngeal network regulates feeding rate. These results identify two different mechanisms by which degeneracy is manifest in a neural circuit in vivo.
Collapse
Affiliation(s)
- Nicholas F Trojanowski
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Olivia Padovan-Merhar
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David M Raizen
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Christopher Fang-Yen
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul, South Korea
| |
Collapse
|
77
|
Glebov K, Voronezhskaya EE, Khabarova MY, Ivashkin E, Nezlin LP, Ponimaskin EG. Mechanisms underlying dual effects of serotonin during development of Helisoma trivolvis (Mollusca). BMC DEVELOPMENTAL BIOLOGY 2014; 14:14. [PMID: 24625099 PMCID: PMC4007640 DOI: 10.1186/1471-213x-14-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 02/21/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND Serotonin (5-HT) is well known as widely distributed modulator of developmental processes in both vertebrates and invertebrates. It is also the earliest neurotransmitter to appear during neuronal development. In aquatic invertebrates, which have larvae in their life cycle, 5-HT is involved in regulation of stages transition including larval metamorphosis and settlement. However, molecular and cellular mechanisms underlying developmental transition in aquatic invertebrate species are yet poorly understood. Earlier we demonstrated that in larvae of freshwater molluscs and marine polychaetes, endogenous 5-HT released from the neurons of the apical sensory organ (ASO) in response to external stimuli retarded larval development at premetamorphic stages, and accelerated it at metamorphic stages. Here we used a freshwater snail Helisoma trivolvis to study molecular mechanisms underlying these dual developmental effects of 5-HT. RESULTS Larval development of H. trivolvis includes transition from premetamorphic to metamorphic stages and shares the main features of metamorphosis with free-swimming aquatic larvae. Three types of 5-HT receptors (5-HT1-, 5-HT4- and 5-HT7-like) are functionally active at premetamorphic (trochophore, veliger) and metamorphic (veliconcha) stages, and expression patterns of these receptors and respective G proteins undergo coordinated changes during development. Stimulation of these receptors modulated cAMP-dependent regulation of cell divisions. Expression of 5-HT4- and 5-HT7-like receptors and their downstream Gs protein was down-regulated during the transition of pre- to metamorphic stage, while expression of 5-HT1 -like receptor and its downstream Gi protein was upregulated. In accordance with relative amount of these receptors, stimulation of 5-HTRs at premetamorphic stages induces developmental retardation, while their stimulation at metamorphic stages induces developmental acceleration. CONCLUSIONS We present a novel molecular mechanism that underlies stage-specific changes in developmental tempo of H. trivolvis larvae in response to endogenous 5-HT produced by the neurons of the ASO. We suggest that consecutive changes in expression patterns of different receptors and their downstream partners in the course of larval development represent the molecular base of larval transition from premetamorphic (non-competent) to metamorphic (competent) state.
Collapse
Affiliation(s)
| | | | | | | | | | - Evgeni G Ponimaskin
- DFG-Research Center Molecular Physiology of the Brain (CMPB), Göttingen, Germany.
| |
Collapse
|
78
|
Scharf A, Piechulek A, von Mikecz A. Effect of nanoparticles on the biochemical and behavioral aging phenotype of the nematode Caenorhabditis elegans. ACS NANO 2013; 7:10695-703. [PMID: 24256469 DOI: 10.1021/nn403443r] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Invertebrate animal models such as the nematode Caenorhabditis elegans (C. elegans) are increasingly used in nanotechnological applications. Research in this area covers a wide range from remote control of worm behavior by nanoparticles (NPs) to evaluation of organismal nanomaterial safety. Despite of the broad spectrum of investigated NP-bio interactions, little is known about the role of nanomaterials with respect to aging processes in C. elegans. We trace NPs in single cells of adult C. elegans and correlate particle distribution with the worm's metabolism and organ function. By confocal microscopy analysis of fluorescently labeled NPs in living worms, we identify two entry portals for the uptake of nanomaterials via the pharynx to the intestinal system and via the vulva to the reproductive system. NPs are localized throughout the cytoplasm and the cell nucleus in single intestinal, and vulval B and D cells. Silica NPs induce an untimely accumulation of insoluble ubiquitinated proteins, nuclear amyloid and reduction of pharyngeal pumping that taken together constitute a premature aging phenotype of C. elegans on the molecular and behavioral level, respectively. Screening of different nanomaterials for their effects on protein solubility shows that polystyrene or silver NPs do not induce accumulation of ubiquitinated proteins suggesting that alteration of protein homeostasis is a unique property of silica NPs. The nematode C. elegans represents an excellent model to investigate the effect of different types of nanomaterials on aging at the molecule, cell, and whole organism level.
Collapse
Affiliation(s)
- Andrea Scharf
- IUF-Leibniz Research Institute for Environmental Medicine, Heinrich-Heine-University Duesseldorf , Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | | | | |
Collapse
|
79
|
Serotonergic chemosensory neurons modify the C. elegans immune response by regulating G-protein signaling in epithelial cells. PLoS Pathog 2013; 9:e1003787. [PMID: 24348250 PMCID: PMC3861540 DOI: 10.1371/journal.ppat.1003787] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 10/09/2013] [Indexed: 01/08/2023] Open
Abstract
The nervous and immune systems influence each other, allowing animals to rapidly protect themselves from changes in their internal and external environment. However, the complex nature of these systems in mammals makes it difficult to determine how neuronal signaling influences the immune response. Here we show that serotonin, synthesized in Caenorhabditis elegans chemosensory neurons, modulates the immune response. Serotonin released from these cells acts, directly or indirectly, to regulate G-protein signaling in epithelial cells. Signaling in these cells is required for the immune response to infection by the natural pathogen Microbacterium nematophilum. Here we show that serotonin signaling suppresses the innate immune response and limits the rate of pathogen clearance. We show that C. elegans uses classical neurotransmitters to alter the immune response. Serotonin released from sensory neurons may function to modify the immune system in response to changes in the animal's external environment such as the availability, or quality, of food.
Collapse
|
80
|
Soukas AA, Carr CE, Ruvkun G. Genetic regulation of Caenorhabditis elegans lysosome related organelle function. PLoS Genet 2013; 9:e1003908. [PMID: 24204312 PMCID: PMC3812091 DOI: 10.1371/journal.pgen.1003908] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Accepted: 09/11/2013] [Indexed: 12/28/2022] Open
Abstract
Lysosomes are membrane-bound organelles that contain acid hydrolases that degrade cellular proteins, lipids, nucleic acids, and oligosaccharides, and are important for cellular maintenance and protection against age-related decline. Lysosome related organelles (LROs) are specialized lysosomes found in organisms from humans to worms, and share many of the features of classic lysosomes. Defective LROs are associated with human immune disorders and neurological disease. Caenorhabditis elegans LROs are the site of concentration of vital dyes such as Nile red as well as age-associated autofluorescence. Even though certain short-lived mutants have high LRO Nile red and high autofluorescence, and other long-lived mutants have low LRO Nile red and low autofluorescence, these two biologies are distinct. We identified a genetic pathway that modulates aging-related LRO phenotypes via serotonin signaling and the gene kat-1, which encodes a mitochondrial ketothiolase. Regulation of LRO phenotypes by serotonin and kat-1 in turn depend on the proton-coupled, transmembrane transporter SKAT-1. skat-1 loss of function mutations strongly suppress the high LRO Nile red accumulation phenotype of kat-1 mutation. Using a systems approach, we further analyzed the role of 571 genes in LRO biology. These results highlight a gene network that modulates LRO biology in a manner dependent upon the conserved protein kinase TOR complex 2. The results implicate new genetic pathways involved in LRO biology, aging related physiology, and potentially human diseases of the LRO. Lysosome related organelles (LROs) are specialized, membrane-bound organelles that share many common features of canonical lysosomes. Mutations in critical components of LRO biogenesis lead to human diseases of immunity, blood clotting, and pigmentation. In Caenorhabditis elegans, LROs are the site of accumulation of aging-related autofluorescence and the vital dye Nile red when fed to living C. elegans. Through classical genetics we show that the LRO is regulated by a conserved genetic pathway involving serotonin, a mitochondrial ketothiolase, and a proton-coupled solute transporter. Though previously thought to be linked in an obligatory manner, through systems level analysis we show that accumulation of C. elegans LRO Nile red and autofluorescence are mechanistically distinct processes. Contrary to the prior notion that LRO Nile red indicates lipid stores, we show that LRO Nile red is not correlated with, and may be anticorrelated with, C. elegans lipid stores. Using hundreds of candidate gene inactivations that disrupt Nile red accumulation, we determined which LRO regulatory genes specifically interact with 6 genetic mutants known to have altered LRO biology, identifying changes specifically dependent upon target of rapamycin complex 2 signaling. These data reveal relationships between LRO biology and aging and metabolism in C. elegans.
Collapse
Affiliation(s)
- Alexander A. Soukas
- Center for Human Genetic Research, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (AAS); (GR)
| | - Christopher E. Carr
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Earth and Interplanetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Gary Ruvkun
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (AAS); (GR)
| |
Collapse
|
81
|
Song BM, Avery L. The pharynx of the nematode C. elegans: A model system for the study of motor control. WORM 2013; 2:e21833. [PMID: 24058858 PMCID: PMC3670459 DOI: 10.4161/worm.21833] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 08/14/2012] [Indexed: 11/19/2022]
Abstract
Motor control is a complex process that requires interplay among the nervous system, muscles and environment. The simple anatomy, well-characterized muscle movements and ample resources for molecular and cellular dissection make the pharynx of the nematode C. elegans an attractive model system for the study of motor control. The C. elegans pharynx shows two clear muscle movements that are essential for food intake, pharyngeal pumping and isthmus peristalsis. Here, we review our recent findings on the mechanism by which food activates the feeding motions. To understand this process, we characterized the behavior of the feeding motions in response to serotonin, an endogenous pharyngeal pumping activator whose action is triggered by food. We found that: (1) the timing of onset and frequencies of the two feeding motions are distinct; (2) isthmus peristalsis is selectively coupled to the preceding pump; (3) like food, serotonin activates isthmus peristalsis as well as pharyngeal pumping. By genetic analysis, we showed that two separate neural pathways activate the two feeding motions explaining the differences between the two feeding motions. We also proposed a model that explains how the two feeding motions are separately controlled, yet coupled by the interaction between the nervous system and the muscles in the pharynx. Finally, we briefly discuss future approaches to further understand the mechanism that couples the two feeding motions in C. elegans and to possibly understand evolution of motor control in the pharynx by expanding findings in C. elegans to other nematode species.
Collapse
Affiliation(s)
- Bo-Mi Song
- Department of Physiology and Biophysics; Virginia Commonwealth University; Richmond, VA USA
| | | |
Collapse
|
82
|
Kalinnikova TB, Kolsanova RR, Shagidullin RR, Osipova EB, Gaynutdinov MK. On the role of gene of SER-4 serotonin receptor in thermotolerance of Caenorhabditis elegans behavior. RUSS J GENET+ 2013. [DOI: 10.1134/s1022795413030083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
83
|
Postsynaptic ERG potassium channels limit muscle excitability to allow distinct egg-laying behavior states in Caenorhabditis elegans. J Neurosci 2013; 33:761-75. [PMID: 23303953 DOI: 10.1523/jneurosci.3896-12.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Caenorhabditis elegans regulates egg laying by alternating between an inactive phase and a serotonin-triggered active phase. We found that the conserved ERG [ether-a-go-go (EAG) related gene] potassium channel UNC-103 enables this two-state behavior by limiting excitability of the egg-laying muscles. Using both high-speed video recording and calcium imaging of egg-laying muscles in behaving animals, we found that the muscles appear to be excited at a particular phase of each locomotor body bend. During the inactive phase, this rhythmic excitation infrequently evokes calcium transients or contraction of the egg-laying muscles. During the serotonin-triggered active phase, however, these muscles are more excitable and each body bend is accompanied by a calcium transient that drives twitching or full contraction of the egg-laying muscles. We found that ERG-null mutants lay eggs too frequently, and that ERG function is necessary and sufficient in the egg-laying muscles to limit egg laying. ERG K(+) channels localize to postsynaptic sites in the egg-laying muscle, and mutants lacking ERG have more frequent calcium transients and contractions of the egg-laying muscles even during the inactive phase. Thus ERG channels set postsynaptic excitability at a threshold so that further adjustments of excitability by serotonin generate two distinct behavioral states.
Collapse
|
84
|
Song BM, Faumont S, Lockery S, Avery L. Recognition of familiar food activates feeding via an endocrine serotonin signal in Caenorhabditis elegans. eLife 2013; 2:e00329. [PMID: 23390589 PMCID: PMC3564447 DOI: 10.7554/elife.00329] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 12/22/2012] [Indexed: 02/04/2023] Open
Abstract
Familiarity discrimination has a significant impact on the pattern of food intake across species. However, the mechanism by which the recognition memory controls feeding is unclear. Here, we show that the nematode Caenorhabditis elegans forms a memory of particular foods after experience and displays behavioral plasticity, increasing the feeding response when they subsequently recognize the familiar food. We found that recognition of familiar food activates the pair of ADF chemosensory neurons, which subsequently increase serotonin release. The released serotonin activates the feeding response mainly by acting humorally and directly activates SER-7, a type 7 serotonin receptor, in MC motor neurons in the feeding organ. Our data suggest that worms sense the taste and/or smell of novel bacteria, which overrides the stimulatory effect of familiar bacteria on feeding by suppressing the activity of ADF or its upstream neurons. Our study provides insight into the mechanism by which familiarity discrimination alters behavior.DOI:http://dx.doi.org/10.7554/eLife.00329.001.
Collapse
Affiliation(s)
- Bo-mi Song
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Serge Faumont
- Institute of Neuroscience, University of Oregon, Eugene, United States
| | - Shawn Lockery
- Institute of Neuroscience, University of Oregon, Eugene, United States
| | - Leon Avery
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, United States
| |
Collapse
|
85
|
IRK-1 potassium channels mediate peptidergic inhibition of Caenorhabditis elegans serotonin neurons via a G(o) signaling pathway. J Neurosci 2013; 32:16285-95. [PMID: 23152612 DOI: 10.1523/jneurosci.2667-12.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To identify molecular mechanisms that function in G-protein signaling, we have performed molecular genetic studies of a simple behavior of the nematode Caenorhabditis elegans, egg laying, which is driven by a pair of serotonergic neurons, the hermaphrodite-specific neurons (HSNs). The activity of the HSNs is regulated by the G(o)-coupled receptor EGL-6, which mediates inhibition of the HSNs by neuropeptides. We report here that this inhibition requires one of three inwardly rectifying K(+) channels encoded by the C. elegans genome: IRK-1. Using ChannelRhodopsin-2-mediated stimulation of HSNs, we observed roles for egl-6 and irk-1 in regulating the excitability of HSNs. Although irk-1 is required for inhibition of HSNs by EGL-6 signaling, we found that other G(o) signaling pathways that inhibit HSNs involve irk-1 little or not at all. These findings suggest that the neuropeptide receptor EGL-6 regulates the potassium channel IRK-1 via a dedicated pool of G(o) not involved in other G(o)-mediated signaling. We conclude that G-protein-coupled receptors that signal through the same G-protein in the same cell might activate distinct effectors and that specific coupling of a G-protein-coupled receptor to its effectors can be determined by factors other than its associated G-proteins.
Collapse
|
86
|
Gürel G, Gustafson MA, Pepper JS, Horvitz HR, Koelle MR. Receptors and other signaling proteins required for serotonin control of locomotion in Caenorhabditis elegans. Genetics 2012; 192:1359-71. [PMID: 23023001 PMCID: PMC3512144 DOI: 10.1534/genetics.112.142125] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 09/15/2012] [Indexed: 01/05/2023] Open
Abstract
A better understanding of the molecular mechanisms of signaling by the neurotransmitter serotonin is required to assess the hypothesis that defects in serotonin signaling underlie depression in humans. Caenorhabditis elegans uses serotonin as a neurotransmitter to regulate locomotion, providing a genetic system to analyze serotonin signaling. From large-scale genetic screens we identified 36 mutants of C. elegans in which serotonin fails to have its normal effect of slowing locomotion, and we molecularly identified eight genes affected by 19 of the mutations. Two of the genes encode the serotonin-gated ion channel MOD-1 and the G-protein-coupled serotonin receptor SER-4. mod-1 is expressed in the neurons and muscles that directly control locomotion, while ser-4 is expressed in an almost entirely non-overlapping set of sensory and interneurons. The cells expressing the two receptors are largely not direct postsynaptic targets of serotonergic neurons. We analyzed animals lacking or overexpressing the receptors in various combinations using several assays for serotonin response. We found that the two receptors act in parallel to affect locomotion. Our results show that serotonin functions as an extrasynaptic signal that independently activates multiple receptors at a distance from its release sites and identify at least six additional proteins that appear to act with serotonin receptors to mediate serotonin response.
Collapse
Affiliation(s)
- Güliz Gürel
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Megan A. Gustafson
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Judy S. Pepper
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Michael R. Koelle
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520
| |
Collapse
|
87
|
Röser C, Jordan N, Balfanz S, Baumann A, Walz B, Baumann O, Blenau W. Molecular and pharmacological characterization of serotonin 5-HT2α and 5-HT7 receptors in the salivary glands of the blowfly Calliphora vicina. PLoS One 2012; 7:e49459. [PMID: 23145175 PMCID: PMC3493529 DOI: 10.1371/journal.pone.0049459] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 10/09/2012] [Indexed: 11/18/2022] Open
Abstract
Secretion in blowfly (Calliphora vicina) salivary glands is stimulated by the biogenic amine serotonin (5-hydroxytryptamine, 5-HT), which activates both inositol 1,4,5-trisphosphate (InsP(3))/Ca(2+) and cyclic adenosine 3',5'-monophosphate (cAMP) signalling pathways in the secretory cells. In order to characterize the signal-inducing 5-HT receptors, we cloned two cDNAs (Cv5-ht2α, Cv5-ht7) that share high similarity with mammalian 5-HT(2) and 5-HT(7) receptor genes, respectively. RT-PCR demonstrated that both receptors are expressed in the salivary glands and brain. Stimulation of Cv5-ht2α-transfected mammalian cells with 5-HT elevates cytosolic [Ca(2+)] in a dose-dependent manner (EC(50) = 24 nM). In Cv5-ht7-transfected cells, 5-HT produces a dose-dependent increase in [cAMP](i) (EC(50) = 4 nM). We studied the pharmacological profile for both receptors. Substances that appear to act as specific ligands of either Cv5-HT(2α) or Cv5-HT(7) in the heterologous expression system were also tested in intact blowfly salivary gland preparations. We observed that 5-methoxytryptamine (100 nM) activates only the Cv5-HT(2α) receptor, 5-carboxamidotryptamine (300 nM) activates only the Cv5-HT(7) receptor, and clozapine (1 µM) antagonizes the effects of 5-HT via Cv5-HT(7) in blowfly salivary glands, providing means for the selective activation of each of the two 5-HT receptor subtypes. This study represents the first comprehensive molecular and pharmacological characterization of two 5-HT receptors in the blowfly and permits the analysis of the physiological role of these receptors, even when co-expressed in cells, and of the modes of interaction between the Ca(2+)- and cAMP-signalling cascades.
Collapse
Affiliation(s)
- Claudia Röser
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Nadine Jordan
- Institute of Complex Systems (ICS-4), Research Center Jülich, Jülich, Germany
| | - Sabine Balfanz
- Institute of Complex Systems (ICS-4), Research Center Jülich, Jülich, Germany
| | - Arnd Baumann
- Institute of Complex Systems (ICS-4), Research Center Jülich, Jülich, Germany
| | - Bernd Walz
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Otto Baumann
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Wolfgang Blenau
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
- Institut für Bienenkunde (Polytechnische Gesellschaft), Goethe University Frankfurt, Oberursel, Germany
| |
Collapse
|
88
|
Cunningham KA, Hua Z, Srinivasan S, Liu J, Lee BH, Edwards RH, Ashrafi K. AMP-activated kinase links serotonergic signaling to glutamate release for regulation of feeding behavior in C. elegans. Cell Metab 2012; 16:113-21. [PMID: 22768843 PMCID: PMC3413480 DOI: 10.1016/j.cmet.2012.05.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 03/08/2012] [Accepted: 05/29/2012] [Indexed: 01/01/2023]
Abstract
Serotonergic regulation of feeding behavior has been studied intensively, both for an understanding of the basic neurocircuitry of energy balance in various organisms and as a therapeutic target for human obesity. However, its underlying molecular mechanisms remain poorly understood. Here, we show that neural serotonin signaling in C. elegans modulates feeding behavior through inhibition of AMP-activated kinase (AMPK) in interneurons expressing the C. elegans counterpart of human SIM1, a transcription factor associated with obesity. In turn, glutamatergic signaling links these interneurons to pharyngeal neurons implicated in feeding behavior. We show that AMPK-mediated regulation of glutamatergic release is conserved in rat hippocampal neurons. These findings reveal cellular and molecular mediators of serotonergic signaling.
Collapse
Affiliation(s)
- Katherine A. Cunningham
- Department of Physiology and Cardiovascular Research Institute and the UCSF Diabetes Center, University of California, San Francisco, San Francisco, California, USA
| | - Zhaolin Hua
- Departments of Physiology and Neurology, University of California, San Francisco, San Francisco, California, USA
| | - Supriya Srinivasan
- Department of Chemical Physiology and Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, USA
| | - Jason Liu
- Department of Physiology and Cardiovascular Research Institute and the UCSF Diabetes Center, University of California, San Francisco, San Francisco, California, USA
| | - Brian H. Lee
- Department of Physiology and Cardiovascular Research Institute and the UCSF Diabetes Center, University of California, San Francisco, San Francisco, California, USA
| | - Robert H. Edwards
- Departments of Physiology and Neurology, University of California, San Francisco, San Francisco, California, USA
| | - Kaveh Ashrafi
- Department of Physiology and Cardiovascular Research Institute and the UCSF Diabetes Center, University of California, San Francisco, San Francisco, California, USA
| |
Collapse
|
89
|
Lockery SR, Hulme SE, Roberts WM, Robinson KJ, Laromaine A, Lindsay TH, Whitesides GM, Weeks JC. A microfluidic device for whole-animal drug screening using electrophysiological measures in the nematode C. elegans. LAB ON A CHIP 2012; 12:2211-20. [PMID: 22588281 PMCID: PMC3372093 DOI: 10.1039/c2lc00001f] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This paper describes the fabrication and use of a microfluidic device for performing whole-animal chemical screens using non-invasive electrophysiological readouts of neuromuscular function in the nematode worm, C. elegans. The device consists of an array of microchannels to which electrodes are attached to form recording modules capable of detecting the electrical activity of the pharynx, a heart-like neuromuscular organ involved in feeding. The array is coupled to a tree-like arrangement of distribution channels that automatically delivers one nematode to each recording module. The same channels are then used to perfuse the recording modules with test solutions while recording the electropharyngeogram (EPG) from each worm with sufficient sensitivity to detect each pharyngeal contraction. The device accurately reported the acute effects of known anthelmintics (anti-nematode drugs) and also correctly distinguished a specific drug-resistant mutant strain of C. elegans from wild type. The approach described here is readily adaptable to parasitic species for the identification of novel anthelmintics. It is also applicable in toxicology and drug discovery programs for human metabolic and degenerative diseases for which C. elegans is used as a model.
Collapse
Affiliation(s)
- Shawn R Lockery
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403-1254, USA.
| | | | | | | | | | | | | | | |
Collapse
|
90
|
Komuniecki R, Law WJ, Jex A, Geldhof P, Gray J, Bamber B, Gasser RB. Monoaminergic signaling as a target for anthelmintic drug discovery: receptor conservation among the free-living and parasitic nematodes. Mol Biochem Parasitol 2012; 183:1-7. [PMID: 22343182 PMCID: PMC3403675 DOI: 10.1016/j.molbiopara.2012.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 02/01/2012] [Accepted: 02/02/2012] [Indexed: 01/20/2023]
Abstract
This review is designed to summarize the information on monoamine-dependent paralysis as a target for anthelmintic development, examine the conservation of monoamine receptors in the genomes of both free-living and parasitic nematodes, and highlight the utility of the Caenorhabditis elegans model system for dissecting the monoaminergic modulation of locomotory decision-making.
Collapse
Affiliation(s)
- Richard Komuniecki
- Department of Biological Sciences, The University of Toledo, Toledo, OH 43606, United States.
| | | | | | | | | | | | | |
Collapse
|
91
|
Estevez AO, Mueller CL, Morgan KL, Szewczyk NJ, Teece L, Miranda-Vizuete A, Estevez M. Selenium induces cholinergic motor neuron degeneration in Caenorhabditis elegans. Neurotoxicology 2012; 33:1021-32. [PMID: 22560997 DOI: 10.1016/j.neuro.2012.04.019] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 04/06/2012] [Accepted: 04/18/2012] [Indexed: 10/28/2022]
Abstract
Selenium is an essential micronutrient required for cellular antioxidant systems, yet at higher doses it induces oxidative stress. Additionally, in vertebrates environmental exposures to toxic levels of selenium can cause paralysis and death. Here we show that selenium-induced oxidative stress leads to decreased cholinergic signaling and degeneration of cholinergic neurons required for movement and egg-laying in Caenorhabditis elegans. Exposure to high levels of selenium leads to proteolysis of a soluble muscle protein through mechanisms suppressible by two pharmacological agents, levamisole and aldicarb which enhance cholinergic signaling in muscle. In addition, animals with reduction-of-function mutations in genes encoding post-synaptic levamisole-sensitive acetylcholine receptor subunits or the vesicular acetylcholine transporter developed impaired forward movement faster during selenium-exposure than normal animals, again confirming that selenium reduces cholinergic signaling. Finally, the antioxidant reduced glutathione, inhibits selenium-induced reductions in egg-laying through a cellular protective mechanism dependent on the C. elegans glutaredoxin, GLRX-21. These studies provide evidence that the environmental toxicant selenium induces neurodegeneration of cholinergic neurons through depletion of glutathione, a mechanism linked to the neuropathology of Alzheimer's disease, amyotrophic lateral sclerosis, and Parkinson's disease.
Collapse
Affiliation(s)
- Annette O Estevez
- Department of Neurology, University of Arizona, Tucson, AZ 85724-5023, USA.
| | | | | | | | | | | | | |
Collapse
|
92
|
Dissecting a central flip-flop circuit that integrates contradictory sensory cues in C. elegans feeding regulation. Nat Commun 2012; 3:776. [PMID: 22491324 DOI: 10.1038/ncomms1780] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 03/08/2012] [Indexed: 01/16/2023] Open
|
93
|
Serotonin activates overall feeding by activating two separate neural pathways in Caenorhabditis elegans. J Neurosci 2012; 32:1920-31. [PMID: 22323705 DOI: 10.1523/jneurosci.2064-11.2012] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Food intake in the nematode Caenorhabditis elegans requires two distinct feeding motions, pharyngeal pumping and isthmus peristalsis. Bacteria, the natural food of C. elegans, activate both feeding motions (Croll, 1978; Horvitz et al., 1982; Chiang et al., 2006). The mechanisms by which bacteria activate the feeding motions are largely unknown. To understand the process, we studied how serotonin, an endogenous pharyngeal pumping activator whose action is triggered by bacteria, activates feeding motions. Here, we show that serotonin, like bacteria, activates overall feeding by activating isthmus peristalsis as well as pharyngeal pumping. During active feeding, the frequencies and the timing of onset of the two motions were distinct, but each isthmus peristalsis was coupled to the preceding pump. We found that serotonin activates the two feeding motions mainly by activating two separate neural pathways in response to bacteria. For activating pumping, the SER-7 serotonin receptor in the MC motor neurons in the feeding organ activated cholinergic transmission from MC to the pharyngeal muscles by activating the Gsα signaling pathway. For activating isthmus peristalsis, SER-7 in the M4 (and possibly M2) motor neuron in the feeding organ activated the G(12)α signaling pathway in a cell-autonomous manner, which presumably activates neurotransmission from M4 to the pharyngeal muscles. Based on our results and previous calcium imaging of pharyngeal muscles (Shimozono et al., 2004), we propose a model that explains how the two feeding motions are separately regulated yet coupled. The feeding organ may have evolved this way to support efficient feeding.
Collapse
|
94
|
Komuniecki R, Harris G, Hapiak V, Wragg R, Bamber B. Monoamines activate neuropeptide signaling cascades to modulate nociception in C. elegans: a useful model for the modulation of chronic pain? INVERTEBRATE NEUROSCIENCE 2011; 12:53-61. [PMID: 22143253 DOI: 10.1007/s10158-011-0127-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 11/15/2011] [Indexed: 12/13/2022]
Abstract
Monoamines and neuropeptides interact to modulate key behaviors in most organisms. This review is focused on the interaction between octopamine (OA) and an array of neuropeptides in the inhibition of a simple, sensory-mediated aversive behavior in the C. elegans model system and describes the role of monoamines in the activation of global peptidergic signaling cascades. OA has been often considered the invertebrate counterpart of norepinephrine, and the review also highlights the similarities between OA inhibition in C. elegans and the noradrenergic modulation of pain in higher organisms.
Collapse
Affiliation(s)
- Rick Komuniecki
- Department of Biological Sciences, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606, USA.
| | | | | | | | | |
Collapse
|
95
|
Wang Y, Tang L, Feng X, Du W, Liu BF. Ethanol interferes with gustatory plasticity in Caenorhabditis elegans. Neurosci Res 2011; 71:341-7. [DOI: 10.1016/j.neures.2011.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/25/2011] [Accepted: 08/18/2011] [Indexed: 12/01/2022]
|
96
|
Ezcurra M, Tanizawa Y, Swoboda P, Schafer WR. Food sensitizes C. elegans avoidance behaviours through acute dopamine signalling. EMBO J 2011; 30:1110-22. [PMID: 21304491 DOI: 10.1038/emboj.2011.22] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 01/07/2011] [Indexed: 01/28/2023] Open
Abstract
Many behavioural states are modulated by food availability and nutritional status. Here, we report that in Caenorhabditis elegans, the presence of an external food source enhances avoidance responses to soluble repellents sensed by the polymodal ASH neurons. This enhancement requires dopamine signalling and is mimicked by exogenous dopamine. Food modulation is dependent on the mechanosensory cilia of the dopaminergic neurons, indicating that dopamine is released in response to sensation of bacteria. Activation of the dopamine neurons leads within seconds to a transient state of increased sensory acuity. In vivo imaging experiments indicate that this dopamine-dependent sensitization results in part from modality-specific increases in the magnitude and duration of gustatory responses in the ASH neurons. The D1-like dopamine receptor DOP-4 acts cell autonomously in ASH to mediate effects on response magnitude. Thus, dopamine functions as a direct signal of the presence of food to control context-dependent behavioural states.
Collapse
Affiliation(s)
- Marina Ezcurra
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | | | | |
Collapse
|
97
|
Luedtke S, O'Connor V, Holden-Dye L, Walker RJ. The regulation of feeding and metabolism in response to food deprivation in Caenorhabditis elegans. INVERTEBRATE NEUROSCIENCE 2010; 10:63-76. [PMID: 21120572 DOI: 10.1007/s10158-010-0112-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 11/18/2010] [Indexed: 12/31/2022]
Abstract
This review considers the factors involved in the regulation of feeding and metabolism in response to food deprivation using Caenorhabditis elegans as a model organism. Some of the sensory neurons and interneurons involved in food intake are described, together with an overview of pharyngeal pumping. A number of chemical transmitters control feeding in C. elegans including 5-hydroxytryptamine (5-HT, serotonin), acetylcholine, glutamate, dopamine, octopamine, and tyramine. The roles of these transmitters are modified by neuropeptides, including FMRFamide-like peptides (FLPs), neuropeptide-like protein (NLPs), and insulin-like peptides. The precise effects of many of these neuropeptides have yet to be elucidated but increasingly they are being shown to play a role in feeding and metabolism in C. elegans. The regulation of fat stores is complex and appears to involve the expression of a large number of genes, many with mammalian homologues, suggesting that fat regulatory signalling is conserved across phyla. Finally, a brief comparison is made between C. elegans and mammals where for both, despite their evolutionary distance, classical transmitters and neuropeptides have anorectic or orexigenic properties. Thus, there is a rationale to support the argument that an understanding of the molecular and genetic basis of feeding and fat regulation in C. elegans may contribute to efforts aimed at the identification of targets for the treatment of conditions associated with abnormal metabolism and obesity.
Collapse
Affiliation(s)
- Sarah Luedtke
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | | | | | | |
Collapse
|
98
|
Kullyev A, Dempsey CM, Miller S, Kuan CJ, Hapiak VM, Komuniecki RW, Griffin CT, Sze JY. A genetic survey of fluoxetine action on synaptic transmission in Caenorhabditis elegans. Genetics 2010; 186:929-41. [PMID: 20739712 PMCID: PMC2975281 DOI: 10.1534/genetics.110.118877] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 08/13/2010] [Indexed: 11/18/2022] Open
Abstract
Fluoxetine is one of the most commonly prescribed medications for many behavioral and neurological disorders. Fluoxetine acts primarily as an inhibitor of the serotonin reuptake transporter (SERT) to block the removal of serotonin from the synaptic cleft, thereby enhancing serotonin signals. While the effects of fluoxetine on behavior are firmly established, debate is ongoing whether inhibition of serotonin reuptake is a sufficient explanation for its therapeutic action. Here, we provide evidence of two additional aspects of fluoxetine action through genetic analyses in Caenorhabditis elegans. We show that fluoxetine treatment and null mutation in the sole SERT gene mod-5 eliminate serotonin in specific neurons. These neurons do not synthesize serotonin but import extracellular serotonin via MOD-5/SERT. Furthermore, we show that fluoxetine acts independently of MOD-5/SERT to regulate discrete properties of acetylcholine (Ach), gamma-aminobutyric acid (GABA), and glutamate neurotransmission in the locomotory circuit. We identified that two G-protein-coupled 5-HT receptors, SER-7 and SER-5, antagonistically regulate the effects of fluoxetine and that fluoxetine binds to SER-7. Epistatic analyses suggest that SER-7 and SER-5 act upstream of AMPA receptor GLR-1 signaling. Our work provides genetic evidence that fluoxetine may influence neuronal functions and behavior by directly targeting serotonin receptors.
Collapse
Affiliation(s)
- Andrey Kullyev
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Catherine M. Dempsey
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Sarah Miller
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Chih-Jen Kuan
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Vera M. Hapiak
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Richard W. Komuniecki
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Christine T. Griffin
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| | - Ji Ying Sze
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461 Department of Biology, National University of Ireland, Maynooth, County Kilare, Ireland Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606
| |
Collapse
|
99
|
Packham R, Walker RJ, Holden-Dye L. The effect of a selective octopamine antagonist, epinastine, on pharyngeal pumping in Caenorhabditis elegans. INVERTEBRATE NEUROSCIENCE 2010; 10:47-52. [PMID: 20967561 DOI: 10.1007/s10158-010-0107-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Accepted: 10/05/2010] [Indexed: 11/30/2022]
Abstract
This paper investigates the effect of epinastine, a selective octopamine antagonist in invertebrates, in Caenorhabditis elegans. Specifically, its ability to block the inhibitory action of octopamine on C. elegans-isolated pharynx was assayed. Isolated pharynxes were stimulated to pump by the addition of 500 nM 5-hydroxytryptamine (5-HT) (113 ± 2 per 30 s, n = 15). Octopamine inhibited the 5-HT-induced pumping in a concentration-dependent manner (threshold 1-5 μM) with a 61 ± 11% inhibition with 50 μM (n = 5). Epinastine (0.1 μM) antagonized the inhibitory response to octopamine (P < 0.001; n = 15). Tyramine also inhibited pharyngeal pumping induced by 5-HT but was less potent than octopamine. Tyramine, 50 μM to 1 mM, gave a transient inhibition e.g. of 40 ± 5% at 50 μM (n = 5). A higher (10 μM) concentration of epinastine was required to block the tryamine response compared with octopamine. It is concluded that epinastine selectively antagonizes the effect of octopamine on C. elegans pharynx. Further studies are required to test its selectivity for octopamine in other tissues and other nematodes.
Collapse
Affiliation(s)
- Rachel Packham
- School of Biological Sciences, University of Southampton, Highfield Campus, Life Sciences Building 85, Southampton, SO17 1BJ, UK
| | | | | |
Collapse
|
100
|
Hypoxia activates a latent circuit for processing gustatory information in C. elegans. Nat Neurosci 2010; 13:610-4. [PMID: 20400959 DOI: 10.1038/nn.2537] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 03/26/2010] [Indexed: 02/06/2023]
Abstract
Dedicated neuronal circuits enable animals to engage in specific behavioral responses to environmental stimuli. We found that hypoxic stress enhanced gustatory sensory perception via previously unknown circuitry in Caenorhabditis elegans. The hypoxia-inducible transcription factor HIF-1 upregulated serotonin (5-HT) expression in specific sensory neurons that are not normally required for chemosensation. 5-HT subsequently promoted hypoxia-enhanced sensory perception by signaling through the metabotropic G protein-coupled receptor SER-7 in an unusual peripheral neuron, the M4 motor neuron. M4 relayed this information back into the CNS via the FMRFamide-related neuropeptide FLP-21 and its cognate receptor, NPR-1. Thus, physiological detection of hypoxia results in the activation of an additional, previously unrecognized circuit for processing sensory information that is not required for sensory processing under normoxic conditions.
Collapse
|