1
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Martin CG, Bent JS, Hill T, Topalidou I, Singhvi A. Epithelial UNC-23 limits mechanical stress to maintain glia-neuron architecture in C. elegans. Dev Cell 2024; 59:1668-1688.e7. [PMID: 38670103 PMCID: PMC11233253 DOI: 10.1016/j.devcel.2024.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/23/2023] [Accepted: 04/03/2024] [Indexed: 04/28/2024]
Abstract
For an organ to maintain correct architecture and function, its diverse cellular components must coordinate their size and shape. Although cell-intrinsic mechanisms driving homotypic cell-cell coordination are known, it is unclear how cell shape is regulated across heterotypic cells. We find that epithelial cells maintain the shape of neighboring sense-organ glia-neuron units in adult Caenorhabditis elegans (C. elegans). Hsp co-chaperone UNC-23/BAG2 prevents epithelial cell shape from deforming, and its loss causes head epithelia to stretch aberrantly during animal movement. In the sense-organ glia, amphid sheath (AMsh), this causes progressive fibroblast growth factor receptor (FGFR)-dependent disruption of the glial apical cytoskeleton. Resultant glial cell shape alteration causes concomitant shape change in glia-associated neuron endings. Epithelial UNC-23 maintenance of glia-neuron shape is specific both spatially, within a defined anatomical zone, and temporally, in a developmentally critical period. As all molecular components uncovered are broadly conserved across central and peripheral nervous systems, we posit that epithelia may similarly regulate glia-neuron architecture cross-species.
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Affiliation(s)
- Cecilia G Martin
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - James S Bent
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Tyler Hill
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Irini Topalidou
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Department of Biological Structure, University of Washington School of Medicine, Seattle, WA 98195, USA.
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2
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Bhar S, Yoon CS, Mai K, Han J, Prajapati DV, Wang Y, Steffen CL, Bailey LS, Basso KB, Butcher RA. An acyl-CoA thioesterase is essential for the biosynthesis of a key dauer pheromone in C. elegans. Cell Chem Biol 2024; 31:1011-1022.e6. [PMID: 38183989 PMCID: PMC11102344 DOI: 10.1016/j.chembiol.2023.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 09/02/2023] [Accepted: 12/10/2023] [Indexed: 01/08/2024]
Abstract
Methyl ketone (MK)-ascarosides represent essential components of several pheromones in Caenorhabditis elegans, including the dauer pheromone, which triggers the stress-resistant dauer larval stage, and the male-attracting sex pheromone. Here, we identify an acyl-CoA thioesterase, ACOT-15, that is required for the biosynthesis of MK-ascarosides. We propose a model in which ACOT-15 hydrolyzes the β-keto acyl-CoA side chain of an ascaroside intermediate during β-oxidation, leading to decarboxylation and formation of the MK. Using comparative metabolomics, we identify additional ACOT-15-dependent metabolites, including an unusual piperidyl-modified ascaroside, reminiscent of the alkaloid pelletierine. The β-keto acid generated by ACOT-15 likely couples to 1-piperideine to produce the piperidyl ascaroside, which is much less dauer-inducing than the dauer pheromone, asc-C6-MK (ascr#2, 1). The bacterial food provided influences production of the piperidyl ascaroside by the worm. Our work shows how the biosynthesis of MK- and piperidyl ascarosides intersect and how bacterial food may impact chemical signaling in the worm.
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Affiliation(s)
- Subhradeep Bhar
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Chi-Su Yoon
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Kevin Mai
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Jungsoo Han
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Dilip V Prajapati
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Yuting Wang
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Candy L Steffen
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Laura S Bailey
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Kari B Basso
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Rebecca A Butcher
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.
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3
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Ray S, Gurung P, Manning RS, Kravchuk AA, Singhvi A. Neuron cilia restrain glial KCC-3 to a microdomain to regulate multisensory processing. Cell Rep 2024; 43:113844. [PMID: 38421867 PMCID: PMC11296322 DOI: 10.1016/j.celrep.2024.113844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/15/2023] [Accepted: 02/06/2024] [Indexed: 03/02/2024] Open
Abstract
Glia interact with multiple neurons, but it is unclear whether their interactions with each neuron are different. Our interrogation at single-cell resolution reveals that a single glial cell exhibits specificity in its interactions with different contacting neurons. Briefly, C. elegans amphid sheath (AMsh) glia apical-like domains contact 12 neuron-endings. At these ad-neuronal membranes, AMsh glia localize the K/Cl transporter KCC-3 to a microdomain exclusively around the thermosensory AFD neuron to regulate its properties. Glial KCC-3 is transported to ad-neuronal regions, where distal cilia of non-AFD glia-associated chemosensory neurons constrain it to a microdomain at AFD-contacting glial membranes. Aberrant KCC-3 localization impacts both thermosensory (AFD) and chemosensory (non-AFD) neuron properties. Thus, neurons can interact non-synaptically through a shared glial cell by regulating microdomain localization of its cues. As AMsh and glia across species compartmentalize multiple cues like KCC-3, we posit that this may be a broadly conserved glial mechanism that modulates information processing across multimodal circuits.
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Affiliation(s)
- Sneha Ray
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Neuroscience Graduate Program, University of Washington, Seattle, WA 98195, USA
| | - Pralaksha Gurung
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Neuroscience Graduate Program, University of Washington, Seattle, WA 98195, USA
| | - R Sean Manning
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Alexandra A Kravchuk
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Department of Biological Structure, University of Washington School of Medicine, Seattle, WA 98195, USA.
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4
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Liska D, Wolfe Z, Norris A. VISTA: visualizing the spatial transcriptome of the C.elegans nervous system. BIOINFORMATICS ADVANCES 2023; 3:vbad127. [PMID: 37810458 PMCID: PMC10560093 DOI: 10.1093/bioadv/vbad127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/07/2023] [Accepted: 09/12/2023] [Indexed: 10/10/2023]
Abstract
Summary Profiling the transcriptomes of single cells without sacrificing spatial information is a major goal of the field of spatial transcriptomics, but current technologies require tradeoffs between single-cell resolution and whole-transcriptome coverage. In one animal species, the nematode worm Caenorhabditis elegans, a comprehensive spatial transcriptome with single-cell resolution is attainable using existing datasets, thanks to the worm's invariant cell lineage and a series of recently generated single cell transcriptomes. Here we present VISTA, which leverages these datasets to provide a visualization of the worm spatial transcriptome, focusing specifically on the nervous system. VISTA allows users to input a query gene and visualize its expression across all neurons in the form of a "spatial heatmap" in which the color of a cell reports the expression level. Underlying gene expression values (in Transcripts Per Million) are displayed when an individual cell is selected. We provide examples of the utility of VISTA for identifying striking new gene expression patterns in specific neurons, and for resolving cellular identities of ambiguous expression patterns generated from in vivo reporter genes. The ability to easily obtain gene-level snapshots of the neuronal spatial transcriptome should facilitate studies on neuron-specific gene expression and regulation and provide a template for the high-resolution spatial transcriptomes the field hopes to obtain for various animal species in the future. Availability and implementation VISTA is freely available at the following URL: https://public.tableau.com/app/profile/smu.oit.data.insights/viz/VISTA_16814210566130/VISTA.
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Affiliation(s)
- David Liska
- Office of Information Technology, Southern Methodist University, Dallas, TX 75205, United States
| | - Zachery Wolfe
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75205, United States
| | - Adam Norris
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75205, United States
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5
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Wang S, Lin D, Cao J, Wang L. APPA Increases Lifespan and Stress Resistance via Lipid Metabolism and Insulin/IGF-1 Signal Pathway in Caenorhabditis elegans. Int J Mol Sci 2023; 24:13682. [PMID: 37761985 PMCID: PMC10531162 DOI: 10.3390/ijms241813682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 08/31/2023] [Accepted: 09/02/2023] [Indexed: 09/29/2023] Open
Abstract
Animal studies have proven that 1-acetyl-5-phenyl-1H-pyrrol-3-yl acetate (APPA) is a powerful antioxidant as a novel aldose reductase inhibitor independently synthesized by our laboratory; however, there is no current information on APPA's anti-aging mechanism. Therefore, this study examined the impact and mechanism of APPA's anti-aging and anti-oxidation capacity using the Caenorhabditis elegans model. The results demonstrated that APPA increases C. elegans' longevity without affecting the typical metabolism of Escherichia coli OP50 (OP50). APPA also had a non-toxic effect on C. elegans, increased locomotor ability, decreased the levels of reactive oxygen species, lipofuscin, and fat, and increased anti-stress capacity. QRT-PCR analysis further revealed that APPA upregulated the expression of antioxidant genes, including sod-3, gst-4, and hsp-16.2, and the critical downstream transcription factors, daf-16, skn-1, and hsf-1 of the insulin/insulin-like growth factor (IGF) receptor, daf-2. In addition, fat-6 and nhr-80 were upregulated. However, the APPA's life-prolonging effects were absent on the daf-2, daf-16, skn-1, and hsf-1 mutants implying that the APPA's life-prolonging mechanism depends on the insulin/IGF-1 signaling system. The transcriptome sequencing also revealed that the mitochondrial route was also strongly associated with the APPA life extension, consistent with mev-1 and isp-1 mutant life assays. These findings aid in the investigation of APPA's longevity extension mechanism.
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Affiliation(s)
| | | | | | - Liping Wang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, China; (S.W.); (D.L.); (J.C.)
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6
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Liska D, Wolfe Z, Norris A. VISTA: Visualizing the Spatial Transcriptome of the C. elegans Nervous System. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538711. [PMID: 37163055 PMCID: PMC10168398 DOI: 10.1101/2023.04.28.538711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Profiling the transcriptomes of single cells without sacrificing spatial information is a major goal of the field of spatial transcriptomics, but current technologies require tradeoffs between single-cell resolution and whole-transcriptome coverage. In one animal species, the nematode worm C. elegans, a comprehensive spatial transcriptome with single-cell resolution is attainable using existing datasets, thanks to the worm's invariant cell lineage and a series of recently-generated single cell transcriptomes. Here we present VISTA, which leverages these datasets to provide a visualization of the worm spatial transcriptome, focusing specifically on the nervous system. VISTA allows users to input a query gene and visualize its expression across all neurons in the form of a "spatial heatmap" in which the color of a cell reports the expression level. Underlying gene expression values (in Transcripts Per Million) are displayed when an individual cell is selected. We provide examples of the utility of VISTA for identifying striking new gene expression patterns in specific neurons, and for resolving cellular identities of ambiguous expression patterns generated from in vivo reporter genes. The ability to easily obtain gene-level snapshots of the neuronal spatial transcriptome should facilitate studies on neuron-specific gene expression and regulation, and provide a template for the high-resolution spatial transcriptomes the field hopes to obtain for various animal species in the future.
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Affiliation(s)
- David Liska
- Office of Information Technology, Southern Methodist University. Dallas, TX USA
| | - Zachery Wolfe
- Department of Biological Sciences, Southern Methodist University. Dallas, TX USA
| | - Adam Norris
- Department of Biological Sciences, Southern Methodist University. Dallas, TX USA
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7
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Thapliyal S, Beets I, Glauser DA. Multisite regulation integrates multimodal context in sensory circuits to control persistent behavioral states in C. elegans. Nat Commun 2023; 14:3052. [PMID: 37236963 DOI: 10.1038/s41467-023-38685-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
Maintaining or shifting between behavioral states according to context is essential for animals to implement fitness-promoting strategies. How the integration of internal state, past experience and sensory inputs orchestrates persistent multidimensional behavioral changes remains poorly understood. Here, we show that C. elegans integrates environmental temperature and food availability over different timescales to engage in persistent dwelling, scanning, global or glocal search strategies matching thermoregulatory and feeding needs. Transition between states, in each case, involves regulating multiple processes including AFD or FLP tonic sensory neurons activity, neuropeptide expression and downstream circuit responsiveness. State-specific FLP-6 or FLP-5 neuropeptide signaling acts on a distributed set of inhibitory GPCR(s) to promote scanning or glocal search, respectively, bypassing dopamine and glutamate-dependent behavioral state control. Integration of multimodal context via multisite regulation in sensory circuits might represent a conserved regulatory logic for a flexible prioritization on the valence of multiple inputs when operating persistent behavioral state transitions.
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Affiliation(s)
- Saurabh Thapliyal
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland.
| | - Isabel Beets
- Neural Signaling and Circuit Plasticity Group, Department of Biology, KU Leuven, 3000, Leuven, Belgium
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8
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Chaubey AH, Sojka SE, Onukwufor JO, Ezak MJ, Vandermeulen MD, Bowitch A, Vodičková A, Wojtovich AP, Ferkey DM. The Caenorhabditis elegans innexin INX-20 regulates nociceptive behavioral sensitivity. Genetics 2023; 223:iyad017. [PMID: 36753530 PMCID: PMC10319955 DOI: 10.1093/genetics/iyad017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 09/03/2022] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
Organisms rely on chemical cues in their environment to indicate the presence or absence of food, reproductive partners, predators, or other harmful stimuli. In the nematode Caenorhabditis elegans, the bilaterally symmetric pair of ASH sensory neurons serves as the primary nociceptors. ASH activation by aversive stimuli leads to backward locomotion and stimulus avoidance. We previously reported a role for guanylyl cyclases in dampening nociceptive sensitivity that requires an innexin-based gap junction network to pass cGMP between neurons. Here, we report that animals lacking function of the gap junction component INX-20 are hypersensitive in their behavioral response to both soluble and volatile chemical stimuli that signal through G protein-coupled receptor pathways in ASH. We find that expressing inx-20 in the ADL and AFD sensory neurons is sufficient to dampen ASH sensitivity, which is supported by new expression analysis of endogenous INX-20 tagged with mCherry via the CRISPR-Cas9 system. Although ADL does not form gap junctions directly with ASH, it does so via gap junctions with the interneuron RMG and the sensory neuron ASK. Ablating either ADL or RMG and ASK also resulted in nociceptive hypersensitivity, suggesting an important role for RMG/ASK downstream of ADL in the ASH modulatory circuit. This work adds to our growing understanding of the repertoire of ways by which ASH activity is regulated via its connectivity to other neurons and identifies a previously unknown role for ADL and RMG in the modulation of aversive behavior.
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Affiliation(s)
- Aditi H Chaubey
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Savannah E Sojka
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - John O Onukwufor
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Meredith J Ezak
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Matthew D Vandermeulen
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Alexander Bowitch
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
| | - Anežka Vodičková
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Andrew P Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Denise M Ferkey
- Department of Biological Sciences, University at Buffalo, State University of New York, Buffalo, NY 14260, USA
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9
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Wong SQ, Ryan CJ, Bonal DM, Mills J, Lapierre LR. Neuronal HLH-30/TFEB modulates peripheral mitochondrial fragmentation to improve thermoresistance in Caenorhabditis elegans. Aging Cell 2023; 22:e13741. [PMID: 36419219 PMCID: PMC10014052 DOI: 10.1111/acel.13741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 09/29/2022] [Accepted: 10/31/2022] [Indexed: 11/25/2022] Open
Abstract
Transcription factor EB (TFEB) is a conserved master transcriptional activator of autophagy and lysosomal genes that modulates organismal lifespan regulation and stress resistance. As neurons can coordinate organism-wide processes, we investigated the role of neuronal TFEB in stress resistance and longevity. To this end, the Caenorhabditis elegans TFEB ortholog, hlh-30, was rescued panneuronally in hlh-30 loss of function mutants. While important in the long lifespan of daf-2 animals, neuronal HLH-30/TFEB was not sufficient to restore normal lifespan in short-lived hlh-30 mutants. However, neuronal HLH-30/TFEB rescue mediated robust improvements in the heat stress resistance of wildtype but not daf-2 animals. Notably, these mechanisms can be uncoupled, as neuronal HLH-30/TFEB requires DAF-16/FOXO to regulate longevity but not thermoresistance. Through further transcriptomics profiling and functional analysis, we discovered that neuronal HLH-30/TFEB modulates neurotransmission through the hitherto uncharacterized protein W06A11.1 by inducing peripheral mitochondrial fragmentation and organismal heat stress resistance in a non-cell autonomous manner. Taken together, this study uncovers a novel mechanism of heat stress protection mediated by neuronal HLH-30/TFEB.
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Affiliation(s)
- Shi Quan Wong
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
| | - Catherine J. Ryan
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
| | - Dennis M. Bonal
- Pathobiology Graduate Program, Division of Biology & MedicineBrown UniversityProvidenceRhode IslandUSA
| | - Joslyn Mills
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
- Department of BiologyWheaton CollegeNortonMassachusettsUSA
| | - Louis R. Lapierre
- Department of Molecular Biology, Cell Biology and BiochemistryBrown UniversityProvidenceRhode IslandUSA
- Département de Chimie et BiochimieUniversité de MonctonMonctonNew BrunswickCanada
- New Brunswick Center for Precision MedicineMonctonNew BrunswickCanada
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10
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Thapliyal S, Glauser DA. Neurogenetic Analysis in Caenorhabditis elegans. Neurogenetics 2023. [DOI: 10.1007/978-3-031-07793-7_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Izquierdo PG, Charvet CL, Neveu C, Green AC, Tattersall JEH, Holden-Dye L, O'Connor V. Modelling organophosphate intoxication in C. elegans highlights nicotinic acetylcholine receptor determinants that mitigate poisoning. PLoS One 2023; 18:e0284786. [PMID: 37083685 PMCID: PMC10121051 DOI: 10.1371/journal.pone.0284786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 04/06/2023] [Indexed: 04/22/2023] Open
Abstract
Organophosphate intoxication via acetylcholinesterase inhibition executes neurotoxicity via hyper stimulation of acetylcholine receptors. Here, we use the organophosphate paraoxon-ethyl to treat C. elegans and use its impact on pharyngeal pumping as a bio-assay to model poisoning through these neurotoxins. This assay provides a tractable measure of acetylcholine receptor mediated contraction of body wall muscle. Investigation of the time dependence of organophosphate treatment and the genetic determinants of the drug-induced inhibition of pumping highlight mitigating modulation of the effects of paraoxon-ethyl. We identified mutants that reduce acetylcholine receptor function protect against the consequence of intoxication by organophosphates. Data suggests that reorganization of cholinergic signalling is associated with organophosphate poisoning. This reinforces the under investigated potential of using therapeutic approaches which target a modulation of nicotinic acetylcholine receptor function to treat the poisoning effects of this important class of neurotoxins.
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Affiliation(s)
- Patricia G Izquierdo
- Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Claude L Charvet
- French National Institute for Agricultural Research (INRA), Infectiologie Animale et Santé Publique, Nouzilly, France
| | - Cedric Neveu
- French National Institute for Agricultural Research (INRA), Infectiologie Animale et Santé Publique, Nouzilly, France
| | - A Christopher Green
- Dstl, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - John E H Tattersall
- Dstl, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - Lindy Holden-Dye
- Dstl, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - Vincent O'Connor
- Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
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12
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Vora M, Pyonteck SM, Popovitchenko T, Matlack TL, Prashar A, Kane NS, Favate J, Shah P, Rongo C. The hypoxia response pathway promotes PEP carboxykinase and gluconeogenesis in C. elegans. Nat Commun 2022; 13:6168. [PMID: 36257965 PMCID: PMC9579151 DOI: 10.1038/s41467-022-33849-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/05/2022] [Indexed: 12/31/2022] Open
Abstract
Actively dividing cells, including some cancers, rely on aerobic glycolysis rather than oxidative phosphorylation to generate energy, a phenomenon termed the Warburg effect. Constitutive activation of the Hypoxia Inducible Factor (HIF-1), a transcription factor known for mediating an adaptive response to oxygen deprivation (hypoxia), is a hallmark of the Warburg effect. HIF-1 is thought to promote glycolysis and suppress oxidative phosphorylation. Here, we instead show that HIF-1 can promote gluconeogenesis. Using a multiomics approach, we reveal the genomic, transcriptomic, and metabolomic landscapes regulated by constitutively active HIF-1 in C. elegans. We use RNA-seq and ChIP-seq under aerobic conditions to analyze mutants lacking EGL-9, a key negative regulator of HIF-1. We integrate these approaches to identify over two hundred genes directly and functionally upregulated by HIF-1, including the PEP carboxykinase PCK-1, a rate-limiting mediator of gluconeogenesis. This activation of PCK-1 by HIF-1 promotes survival in response to both oxidative and hypoxic stress. Our work identifies functional direct targets of HIF-1 in vivo, comprehensively describing the metabolome induced by HIF-1 activation in an organism.
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Affiliation(s)
- Mehul Vora
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Stephanie M Pyonteck
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Tatiana Popovitchenko
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Tarmie L Matlack
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Aparna Prashar
- The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Nanci S Kane
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - John Favate
- The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Premal Shah
- The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Christopher Rongo
- The Waksman Institute, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA. .,The Department of Genetics, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA.
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13
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Izquierdo PG, Calahorro F, Thisainathan T, Atkins JH, Haszczyn J, Lewis CJ, Tattersall JEH, Green AC, Holden-Dye L, O'Connor V. Cholinergic signaling at the body wall neuromuscular junction distally inhibits feeding behavior in Caenorhabditis elegans. J Biol Chem 2021; 298:101466. [PMID: 34864060 PMCID: PMC8801469 DOI: 10.1016/j.jbc.2021.101466] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 11/13/2021] [Accepted: 11/30/2021] [Indexed: 12/27/2022] Open
Abstract
Complex biological functions within organisms are frequently orchestrated by systemic communication between tissues. In the model organism Caenorhabditis elegans, the pharyngeal and body wall neuromuscular junctions are two discrete structures that control feeding and locomotion, respectively. Separate, the well-defined neuromuscular circuits control these distinct tissues. Nonetheless, the emergent behaviors, feeding and locomotion, are coordinated to guarantee the efficiency of food intake. Here, we show that pharmacological hyperactivation of cholinergic transmission at the body wall muscle reduces the rate of pumping behavior. This was evidenced by a systematic screening of the effect of the cholinesterase inhibitor aldicarb on the rate of pharyngeal pumping on food in mutant worms. The screening revealed that the key determinants of the inhibitory effect of aldicarb on pharyngeal pumping are located at the body wall neuromuscular junction. In fact, the selective stimulation of the body wall muscle receptors with the agonist levamisole inhibited pumping in a lev-1-dependent fashion. Interestingly, this response was independent of unc-38, an alpha subunit of the nicotinic receptor classically expressed with lev-1 at the body wall muscle. This implies an uncharacterized lev-1-containing receptor underpins this effect. Overall, our results reveal that body wall cholinergic transmission not only controls locomotion but simultaneously inhibits feeding behavior.
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Affiliation(s)
- Patricia G Izquierdo
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom.
| | - Fernando Calahorro
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Thibana Thisainathan
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - James H Atkins
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Johanna Haszczyn
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Christian J Lewis
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - John E H Tattersall
- Dstl, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - A Christopher Green
- Dstl, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - Lindy Holden-Dye
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Vincent O'Connor
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
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14
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Lautens MJ, Tan JH, Serrat X, Del Borrello S, Schertzberg MR, Fraser AG. Identification of enzymes that have helminth-specific active sites and are required for Rhodoquinone-dependent metabolism as targets for new anthelmintics. PLoS Negl Trop Dis 2021; 15:e0009991. [PMID: 34843467 PMCID: PMC8659336 DOI: 10.1371/journal.pntd.0009991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 12/09/2021] [Accepted: 11/11/2021] [Indexed: 11/18/2022] Open
Abstract
Soil transmitted helminths (STHs) are major human pathogens that infect over a billion people. Resistance to current anthelmintics is rising and new drugs are needed. Here we combine multiple approaches to find druggable targets in the anaerobic metabolic pathways STHs need to survive in their mammalian host. These require rhodoquinone (RQ), an electron carrier used by STHs and not their hosts. We identified 25 genes predicted to act in RQ-dependent metabolism including sensing hypoxia and RQ synthesis and found 9 are required. Since all 9 have mammalian orthologues, we used comparative genomics and structural modeling to identify those with active sites that differ between host and parasite. Together, we found 4 genes that are required for RQ-dependent metabolism and have different active sites. Finding these high confidence targets can open up in silico screens to identify species selective inhibitors of these enzymes as new anthelmintics.
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Affiliation(s)
- Margot J. Lautens
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - June H. Tan
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Xènia Serrat
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | | | | | - Andrew G. Fraser
- The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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15
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Marques F, Falquet L, Vandewyer E, Beets I, Glauser DA. Signaling via the FLP-14/FRPR-19 neuropeptide pathway sustains nociceptive response to repeated noxious stimuli in C. elegans. PLoS Genet 2021; 17:e1009880. [PMID: 34748554 PMCID: PMC8601619 DOI: 10.1371/journal.pgen.1009880] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/18/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022] Open
Abstract
In order to thrive in constantly changing environments, animals must adaptively respond to threatening events. Noxious stimuli are not only processed according to their absolute intensity, but also to their context. Adaptation processes can cause animals to habituate at different rates and degrees in response to permanent or repeated stimuli. Here, we used a forward genetic approach in Caenorhabditis elegans to identify a neuropeptidergic pathway, essential to prevent fast habituation and maintain robust withdrawal responses to repeated noxious stimuli. This pathway involves the FRPR-19A and FRPR-19B G-protein coupled receptor isoforms produced from the frpr-19 gene by alternative splicing. Loss or overexpression of each or both isoforms can impair withdrawal responses caused by the optogenetic activation of the polymodal FLP nociceptor neuron. Furthermore, we identified FLP-8 and FLP-14 as FRPR-19 ligands in vitro. flp-14, but not flp-8, was essential to promote withdrawal response and is part of the same genetic pathway as frpr-19 in vivo. Expression and cell-specific rescue analyses suggest that FRPR-19 acts both in the FLP nociceptive neurons and downstream interneurons, whereas FLP-14 acts from interneurons. Importantly, genetic impairment of the FLP-14/FRPR-19 pathway accelerated the habituation to repeated FLP-specific optogenetic activation, as well as to repeated noxious heat and harsh touch stimuli. Collectively, our data suggest that well-adjusted neuromodulation via the FLP-14/FRPR-19 pathway contributes to promote nociceptive signals in C. elegans and counteracts habituation processes that otherwise tend to rapidly reduce aversive responses to repeated noxious stimuli.
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Affiliation(s)
- Filipe Marques
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Laurent Falquet
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Elke Vandewyer
- Neural Signaling and Circuit Plasticity Group, Department of Biology, KU Leuven, Leuven, Belgium
| | - Isabel Beets
- Neural Signaling and Circuit Plasticity Group, Department of Biology, KU Leuven, Leuven, Belgium
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16
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Katsanos D, Ferrando-Marco M, Razzaq I, Aughey G, Southall TD, Barkoulas M. Gene expression profiling of epidermal cell types in C. elegans using Targeted DamID. Development 2021; 148:dev199452. [PMID: 34397094 PMCID: PMC7613258 DOI: 10.1242/dev.199452] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 08/05/2021] [Indexed: 12/19/2022]
Abstract
The epidermis of Caenorhabditis elegans is an essential tissue for survival because it contributes to the formation of the cuticle barrier as well as facilitating developmental progression and animal growth. Most of the epidermis consists of the hyp7 hypodermal syncytium, the nuclei of which are largely generated by the seam cells, which exhibit stem cell-like behaviour during development. How seam cell progenitors differ transcriptionally from the differentiated hypodermis is poorly understood. Here, we introduce Targeted DamID (TaDa) in C. elegans as a method for identifying genes expressed within a tissue of interest without cell isolation. We show that TaDa signal enrichment profiles can be used to identify genes transcribed in the epidermis and use this method to resolve differences in gene expression between the seam cells and the hypodermis. Finally, we predict and functionally validate new transcription and chromatin factors acting in seam cell development. These findings provide insights into cell type-specific gene expression profiles likely associated with epidermal cell fate patterning.
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Affiliation(s)
- Dimitris Katsanos
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Mar Ferrando-Marco
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Iqrah Razzaq
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Gabriel Aughey
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Tony D. Southall
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Michalis Barkoulas
- Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
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17
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Raiders S, Black EC, Bae A, MacFarlane S, Klein M, Shaham S, Singhvi A. Glia actively sculpt sensory neurons by controlled phagocytosis to tune animal behavior. eLife 2021; 10:63532. [PMID: 33759761 PMCID: PMC8079151 DOI: 10.7554/elife.63532] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/23/2021] [Indexed: 02/07/2023] Open
Abstract
Glia in the central nervous system engulf neuron fragments to remodel synapses and recycle photoreceptor outer segments. Whether glia passively clear shed neuronal debris or actively prune neuron fragments is unknown. How pruning of single-neuron endings impacts animal behavior is also unclear. Here, we report our discovery of glia-directed neuron pruning in Caenorhabditis elegans. Adult C. elegans AMsh glia engulf sensory endings of the AFD thermosensory neuron by repurposing components of the conserved apoptotic corpse phagocytosis machinery. The phosphatidylserine (PS) flippase TAT-1/ATP8A functions with glial PS-receptor PSR-1/PSR and PAT-2/α-integrin to initiate engulfment. This activates glial CED-10/Rac1 GTPase through the ternary GEF complex of CED-2/CrkII, CED-5/DOCK180, CED-12/ELMO. Execution of phagocytosis uses the actin-remodeler WSP-1/nWASp. This process dynamically tracks AFD activity and is regulated by temperature, the AFD sensory input. Importantly, glial CED-10 levels regulate engulfment rates downstream of neuron activity, and engulfment-defective mutants exhibit altered AFD-ending shape and thermosensory behavior. Our findings reveal a molecular pathway underlying glia-dependent engulfment in a peripheral sense-organ and demonstrate that glia actively engulf neuron fragments, with profound consequences on neuron shape and animal sensory behavior. Neurons are tree-shaped cells that receive information through endings connected to neighbouring cells or the environment. Controlling the size, number and location of these endings is necessary to ensure that circuits of neurons get precisely the right amount of input from their surroundings. Glial cells form a large portion of the nervous system, and they are tasked with supporting, cleaning and protecting neurons. In humans, part of their duties is to ‘eat’ (or prune) unnecessary neuron endings. In fact, this role is so important that defects in glial pruning are associated with conditions such as Alzheimer’s disease. Yet it is still unknown how pruning takes place, and in particular whether it is the neuron or the glial cell that initiates the process. To investigate this question, Raiders et al. enlisted the common laboratory animal Caenorhabditis elegans, a tiny worm with a simple nervous system where each neuron has been meticulously mapped out. First, the experiments showed that glial cells in C. elegans actually prune the endings of sensory neurons. Focusing on a single glia-neuron pair then revealed that the glial cell could trim the endings of a living neuron by redeploying the same molecular machinery it uses to clear dead cell debris. Compared to this debris-clearing activity, however, the glial cell takes a more nuanced approach to pruning: specifically, it can adjust the amount of trimming based on the activity load of the neuron. When Raiders et al. disrupted the glial pruning for a single temperature-sensing neuron, the worm lost its normal temperature preferences; this demonstrated how the pruning activity of a single glial cell can be linked to behavior. Taken together the experiments showcase how C. elegans can be used to study glial pruning. Further work using this model could help to understand how disease emerges when glial cells cannot perform their role, and to spot the genetic factors that put certain individuals at increased risk for neurological and sensory disorders.
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Affiliation(s)
- Stephan Raiders
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, United States
| | - Erik Calvin Black
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Andrea Bae
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States.,Cellular Imaging Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Stephen MacFarlane
- Department of Physics and Department of Biology, University of Miami, Coral Gables, United States
| | - Mason Klein
- Department of Physics and Department of Biology, University of Miami, Coral Gables, United States
| | - Shai Shaham
- Laboratory of Developmental Genetics, The Rockefeller University, New York, United States
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, United States.,Department of Biological Structure, University of Washington School of Medicine, Seattle, United States.,Brotman Baty Institute for Precision Medicine, Seattle, United States
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18
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Luth ES, Hodul M, Rennich BJ, Riccio C, Hofer J, Markoja K, Juo P. VER/VEGF receptors regulate AMPA receptor surface levels and glutamatergic behavior. PLoS Genet 2021; 17:e1009375. [PMID: 33561120 PMCID: PMC7899335 DOI: 10.1371/journal.pgen.1009375] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 02/22/2021] [Accepted: 01/22/2021] [Indexed: 01/09/2023] Open
Abstract
Several intracellular trafficking pathways contribute to the regulation of AMPA receptor (AMPAR) levels at synapses and the control of synaptic strength. While much has been learned about these intracellular trafficking pathways, a major challenge is to understand how extracellular factors, such as growth factors, neuropeptides and hormones, impinge on specific AMPAR trafficking pathways to alter synaptic function and behavior. Here, we identify the secreted ligand PVF-1 and its cognate VEGF receptor homologs, VER-1 and VER-4, as regulators of glutamate signaling in C. elegans. Loss of function mutations in ver-1, ver-4, or pvf-1, result in decreased cell surface levels of the AMPAR GLR-1 and defects in glutamatergic behavior. Rescue experiments indicate that PVF-1 is expressed and released from muscle, whereas the VERs function in GLR-1-expressing neurons to regulate surface levels of GLR-1 and glutamatergic behavior. Additionally, ver-4 is unable to rescue glutamatergic behavior in the absence of pvf-1, suggesting that VER function requires endogenous PVF-1. Inducible expression of a pvf-1 rescuing transgene suggests that PVF-1 can function in the mature nervous system to regulate GLR-1 signaling. Genetic double mutant analysis suggests that the VERs act together with the VPS-35/retromer recycling complex to promote cell surface levels of GLR-1. Our data support a genetic model whereby PVF-1/VER signaling acts with retromer to promote recycling and cell surface levels of GLR-1 to control behavior. Sensation, behavior, and cognition all depend on the proper function of neuronal connections called synapses. Synapses that use the neurotransmitter glutamate to signal between nerve cells are the most abundant type in our brain. Presynaptic neurons release glutamate, which activates glutamate receptors on postsynaptic neurons. Dysfunction of glutamate synapses leads to several neurological disorders, and changing their strength–in part by altering glutamate receptors numbers on the surface of the postsynaptic cell—provides the cellular basis of learning and memory. Much remains to be learned about how factors released from other cell types affects synaptic communication. We took advantage of light-activated molecular switches engineered into specific sensory neurons of C. elegans worms to trigger a behavioral reflex that depends on glutamate synapses. Using this behavior, we identified proteins called VER-1 and VER-4 as important for glutamate synapse function. We found that worms missing these VER proteins or their activator PVF-1 have reduced levels of glutamate receptors at the postsynaptic surface and defects in glutamate-dependent behaviors. Our results suggest that inter-tissue cross-talk between muscle PVF-1 and neuronal VERs is important for controlling the number of glutamate receptors at the cell surface, robust neuronal communication and behavioral responses.
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Affiliation(s)
- Eric S. Luth
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Department of Biology, Simmons University, Boston, Massachusetts, United States of America
| | - Molly Hodul
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Program in Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Bethany J. Rennich
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Program in Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Carmino Riccio
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Julia Hofer
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Kaitlin Markoja
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Peter Juo
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Program in Neuroscience, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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19
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Wang M, Witvliet D, Wu M, Kang L, Shao Z. Temperature regulates synaptic subcellular specificity mediated by inhibitory glutamate signaling. PLoS Genet 2021; 17:e1009295. [PMID: 33428618 PMCID: PMC7822552 DOI: 10.1371/journal.pgen.1009295] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 01/22/2021] [Accepted: 12/05/2020] [Indexed: 01/13/2023] Open
Abstract
Environmental factors such as temperature affect neuronal activity and development. However, it remains unknown whether and how they affect synaptic subcellular specificity. Here, using the nematode Caenorhabditis elegans AIY interneurons as a model, we found that high cultivation temperature robustly induces defects in synaptic subcellular specificity through glutamatergic neurotransmission. Furthermore, we determined that the functional glutamate is mainly released by the ASH sensory neurons and sensed by two conserved inhibitory glutamate-gated chloride channels GLC-3 and GLC-4 in AIY. Our work not only presents a novel neurotransmission-dependent mechanism underlying the synaptic subcellular specificity, but also provides a potential mechanistic insight into high-temperature-induced neurological defects.
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Affiliation(s)
- Mengqing Wang
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Daniel Witvliet
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Mengting Wu
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lijun Kang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Zhiyong Shao
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
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20
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van der Burght SN, Rademakers S, Johnson JL, Li C, Kremers GJ, Houtsmuller AB, Leroux MR, Jansen G. Ciliary Tip Signaling Compartment Is Formed and Maintained by Intraflagellar Transport. Curr Biol 2020; 30:4299-4306.e5. [DOI: 10.1016/j.cub.2020.08.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 07/13/2020] [Accepted: 08/07/2020] [Indexed: 02/07/2023]
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21
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Tissue-Specific Transcription Footprinting Using RNA PoI DamID (RAPID) in Caenorhabditis elegans. Genetics 2020; 216:931-945. [PMID: 33037050 PMCID: PMC7768263 DOI: 10.1534/genetics.120.303774] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/09/2020] [Indexed: 11/23/2022] Open
Abstract
Differential gene expression across cell types underlies development and cell physiology in multicellular organisms. Caenorhabditis elegans is a powerful, extensively used model to address these biological questions. A remaining bottleneck relates to the difficulty to obtain comprehensive tissue-specific gene transcription data, since available methods are still challenging to execute and/or require large worm populations. Here, we introduce the RNA Polymerase DamID (RAPID) approach, in which the Dam methyltransferase is fused to a ubiquitous RNA polymerase subunit to create transcriptional footprints via methyl marks on the DNA of transcribed genes. To validate the method, we determined the polymerase footprints in whole animals, in sorted embryonic blastomeres and in different tissues from intact young adults by driving tissue-specific Dam fusion expression. We obtained meaningful transcriptional footprints in line with RNA-sequencing (RNA-seq) studies in whole animals or specific tissues. To challenge the sensitivity of RAPID and demonstrate its utility to determine novel tissue-specific transcriptional profiles, we determined the transcriptional footprints of the pair of XXX neuroendocrine cells, representing 0.2% of the somatic cell content of the animals. We identified 3901 candidate genes with putatively active transcription in XXX cells, including the few previously known markers for these cells. Using transcriptional reporters for a subset of new hits, we confirmed that the majority of them were expressed in XXX cells and identified novel XXX-specific markers. Taken together, our work establishes RAPID as a valid method for the determination of RNA polymerase footprints in specific tissues of C. elegans without the need for cell sorting or RNA tagging.
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22
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Saro G, Lia AS, Thapliyal S, Marques F, Busch KE, Glauser DA. Specific Ion Channels Control Sensory Gain, Sensitivity, and Kinetics in a Tonic Thermonociceptor. Cell Rep 2020; 30:397-408.e4. [DOI: 10.1016/j.celrep.2019.12.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 10/17/2019] [Accepted: 12/06/2019] [Indexed: 10/25/2022] Open
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23
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Epidermal Growth Factor Signaling Promotes Sleep through a Combined Series and Parallel Neural Circuit. Curr Biol 2019; 30:1-16.e13. [PMID: 31839447 DOI: 10.1016/j.cub.2019.10.048] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 07/12/2019] [Accepted: 10/23/2019] [Indexed: 11/20/2022]
Abstract
Sleep requires sleep-active neurons that depolarize to inhibit wake circuits. Sleep-active neurons are under the control of homeostatic mechanisms that determine sleep need. However, little is known about the molecular and circuit mechanisms that translate sleep need into the depolarization of sleep-active neurons. During many stages and conditions in C. elegans, sleep requires a sleep-active neuron called RIS. Here, we defined the transcriptome of RIS and discovered that genes of the epidermal growth factor receptor (EGFR) signaling pathway are expressed in RIS. Because of cellular stress, EGFR directly activates RIS. Activation of EGFR signaling in the ALA neuron has previously been suggested to promote sleep independently of RIS. Unexpectedly, we found that ALA activation promotes RIS depolarization. Our results suggest that ALA is a drowsiness neuron with two separable functions: (1) it inhibits specific behaviors, such as feeding, independently of RIS, (2) and it activates RIS. Whereas ALA plays a strong role in surviving cellular stress, surprisingly, RIS does not. In summary, EGFR signaling can depolarize RIS by an indirect mechanism through activation of the ALA neuron that acts upstream of the sleep-active RIS neuron and through a direct mechanism using EGFR signaling in RIS. ALA-dependent drowsiness, rather than RIS-dependent sleep bouts, appears to be important for increasing survival after cellular stress, suggesting that different types of behavioral inhibition play different roles in restoring health. VIDEO ABSTRACT.
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24
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Chute CD, DiLoreto EM, Zhang YK, Reilly DK, Rayes D, Coyle VL, Choi HJ, Alkema MJ, Schroeder FC, Srinivasan J. Co-option of neurotransmitter signaling for inter-organismal communication in C. elegans. Nat Commun 2019; 10:3186. [PMID: 31320626 PMCID: PMC6639374 DOI: 10.1038/s41467-019-11240-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 06/28/2019] [Indexed: 12/22/2022] Open
Abstract
Biogenic amine neurotransmitters play a central role in metazoan biology, and both their chemical structures and cognate receptors are evolutionarily conserved. Their primary roles are in cell-to-cell signaling, as biogenic amines are not normally recruited for communication between separate individuals. Here, we show that in the nematode C. elegans, a neurotransmitter-sensing G protein-coupled receptor, TYRA-2, is required for avoidance responses to osas#9, an ascaroside pheromone that incorporates the neurotransmitter, octopamine. Neuronal ablation, cell-specific genetic rescue, and calcium imaging show that tyra-2 expression in the nociceptive neuron, ASH, is necessary and sufficient to induce osas#9 avoidance. Ectopic expression in the AWA neuron, which is generally associated with attractive responses, reverses the response to osas#9, resulting in attraction instead of avoidance behavior, confirming that TYRA-2 partakes in the sensing of osas#9. The TYRA-2/osas#9 signaling system represents an inter-organismal communication channel that evolved via co-option of a neurotransmitter and its cognate receptor.
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Affiliation(s)
- Christopher D Chute
- Biology and Biotechnology Department, Worcester Polytechnic Institute, Worcester, MA, 01605, USA
- BioHelix Corporation, Beverly, MA, 01915, USA
| | - Elizabeth M DiLoreto
- Biology and Biotechnology Department, Worcester Polytechnic Institute, Worcester, MA, 01605, USA
| | - Ying K Zhang
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Douglas K Reilly
- Biology and Biotechnology Department, Worcester Polytechnic Institute, Worcester, MA, 01605, USA
| | - Diego Rayes
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, 01605, USA
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (CONICET), Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, B8000, Argentina
| | - Veronica L Coyle
- Biology and Biotechnology Department, Worcester Polytechnic Institute, Worcester, MA, 01605, USA
- AbbVie, Cambridge, MA, 02139, USA
| | - Hee June Choi
- Biomedical Engineering Department, Worcester Polytechnic Institute, Worcester, MA, 01605, USA
| | - Mark J Alkema
- Neurobiology Department, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jagan Srinivasan
- Biology and Biotechnology Department, Worcester Polytechnic Institute, Worcester, MA, 01605, USA.
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25
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Maxeiner S, Grolleman J, Schmid T, Kammenga J, Hajnal A. The hypoxia-response pathway modulates RAS/MAPK-mediated cell fate decisions in Caenorhabditis elegans. Life Sci Alliance 2019; 2:e201800255. [PMID: 31126994 PMCID: PMC6536719 DOI: 10.26508/lsa.201800255] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 01/01/2023] Open
Abstract
Animals need to adjust many cellular functions to oxygen availability to adapt to changing environmental conditions. We have used the nematode Caenorhabditis elegans as a model to investigate how variations in oxygen concentrations affect cell fate specification during development. Here, we show that several processes controlled by the conserved RTK/RAS/MAPK pathway are sensitive to changes in the atmospheric oxygen concentration. In the vulval precursor cells (VPCs), the hypoxia-inducible factor HIF-1 activates the expression of the nuclear hormone receptor NHR-57 to counteract RAS/MAPK-induced differentiation. Furthermore, cross-talk between the NOTCH and hypoxia-response pathways modulates the capability of the VPCs to respond to RAS/MAPK signaling. Lateral NOTCH signaling positively regulates the prolyl hydroxylase EGL-9, which promotes HIF-1 degradation in uncommitted VPCs and permits RAS/MAPK-induced differentiation. By inducing DELTA family NOTCH ligands, RAS/MAPK signaling creates a positive feedback loop that represses HIF-1 and NHR-57 expression in the proximal VPCs and keeps them capable of differentiating. This regulatory network formed by the NOTCH, hypoxia, and RAS/MAPK pathways may allow the animals to adapt developmental processes to variations in oxygen concentration.
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Affiliation(s)
- Sabrina Maxeiner
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
- PhD Program in Molecular Life Sciences, University and ETH Zurich, Zurich, Switzerland
| | - Judith Grolleman
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Tobias Schmid
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Jan Kammenga
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands
| | - Alex Hajnal
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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26
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Kanzaki N, Tsai IJ, Tanaka R, Hunt VL, Liu D, Tsuyama K, Maeda Y, Namai S, Kumagai R, Tracey A, Holroyd N, Doyle SR, Woodruff GC, Murase K, Kitazume H, Chai C, Akagi A, Panda O, Ke HM, Schroeder FC, Wang J, Berriman M, Sternberg PW, Sugimoto A, Kikuchi T. Biology and genome of a newly discovered sibling species of Caenorhabditis elegans. Nat Commun 2018; 9:3216. [PMID: 30097582 PMCID: PMC6086898 DOI: 10.1038/s41467-018-05712-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 07/19/2018] [Indexed: 01/19/2023] Open
Abstract
A 'sibling' species of the model organism Caenorhabditis elegans has long been sought for use in comparative analyses that would enable deep evolutionary interpretations of biological phenomena. Here, we describe the first sibling species of C. elegans, C. inopinata n. sp., isolated from fig syconia in Okinawa, Japan. We investigate the morphology, developmental processes and behaviour of C. inopinata, which differ significantly from those of C. elegans. The 123-Mb C. inopinata genome was sequenced and assembled into six nuclear chromosomes, allowing delineation of Caenorhabditis genome evolution and revealing unique characteristics, such as highly expanded transposable elements that might have contributed to the genome evolution of C. inopinata. In addition, C. inopinata exhibits massive gene losses in chemoreceptor gene families, which could be correlated with its limited habitat area. We have developed genetic and molecular techniques for C. inopinata; thus C. inopinata provides an exciting new platform for comparative evolutionary studies.
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Affiliation(s)
- Natsumi Kanzaki
- Forestry and Forest Products Research Institute, Tsukuba, 305-8687, Japan
- Kansai Research Center, Forestry and Forest Products Research Institute, 68 Nagaikyutaroh, Momoyama, Fushimi, Kyoto, 612-0855, Japan
| | - Isheng J Tsai
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Ryusei Tanaka
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Vicky L Hunt
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Dang Liu
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Kenji Tsuyama
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Yasunobu Maeda
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Satoshi Namai
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Ryohei Kumagai
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Alan Tracey
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Nancy Holroyd
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Stephen R Doyle
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Gavin C Woodruff
- Forestry and Forest Products Research Institute, Tsukuba, 305-8687, Japan
- Department of Biology, Institute of Ecology and Evolution, University of Oregon, Eugene, OR, 97403-5289, USA
| | - Kazunori Murase
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Hiromi Kitazume
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Cynthia Chai
- HHMI and Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, USA
| | - Allison Akagi
- HHMI and Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, USA
| | - Oishika Panda
- Boyce Thompson Institute, and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Huei-Mien Ke
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Frank C Schroeder
- Boyce Thompson Institute, and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - John Wang
- Biodiversity Research Center, Academia Sinica, Taipei city, 11529, Taiwan
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA, UK
| | - Paul W Sternberg
- HHMI and Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, USA
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
| | - Taisei Kikuchi
- Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan.
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27
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Lim JP, Fehlauer H, Das A, Saro G, Glauser DA, Brunet A, Goodman MB. Loss of CaMKI Function Disrupts Salt Aversive Learning in C. elegans. J Neurosci 2018; 38:6114-6129. [PMID: 29875264 PMCID: PMC6031575 DOI: 10.1523/jneurosci.1611-17.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 04/16/2018] [Accepted: 05/25/2018] [Indexed: 11/21/2022] Open
Abstract
The ability to adapt behavior to environmental fluctuations is critical for survival of organisms ranging from invertebrates to mammals. Caenorhabditis elegans can learn to avoid sodium chloride when it is paired with starvation. This behavior may help animals avoid areas without food. Although some genes have been implicated in this salt-aversive learning behavior, critical genetic components, and the neural circuit in which they act, remain elusive. Here, we show that the sole worm ortholog of mammalian CaMKI/IV, CMK-1, is essential for salt-aversive learning behavior in C. elegans hermaphrodites. We find that CMK-1 acts in the primary salt-sensing ASE neurons to regulate this behavior. By characterizing the intracellular calcium dynamics in ASE neurons using microfluidics, we find that loss of cmk-1 has subtle effects on sensory-evoked calcium responses in ASE axons and their modulation by salt conditioning. Our study implicates the expression of the conserved CaMKI/CMK-1 in chemosensory neurons as a regulator of behavioral plasticity to environmental salt in C. elegansSIGNIFICANCE STATEMENT Like other animals, the nematode Caenorhabditis elegans depends on salt for survival and navigates toward high concentrations of this essential mineral. In addition to its role as an essential nutrient, salt also causes osmotic stress at high concentrations. A growing body of evidence indicates that C. elegans balances the requirement for salt with the danger it presents through a process called salt-aversive learning. We show that this behavior depends on expression of a calcium/calmodulin-dependent kinase, CMK-1, in the ASE salt-sensing neurons. Our study identifies CMK-1 and salt-sensitive chemosensory neurons as key factors in this form of behavioral plasticity.
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Affiliation(s)
- Jana P Lim
- Neurosciences Graduate Program
- Department of Genetics
- Department of Molecular and Cellular Physiology
| | | | | | - Gabriella Saro
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | | | - Anne Brunet
- Neurosciences Graduate Program,
- Department of Genetics
- Glenn Center for the Biology of Aging at Stanford University, Stanford, California 94305, and
| | - Miriam B Goodman
- Neurosciences Graduate Program,
- Department of Molecular and Cellular Physiology
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28
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Vuong-Brender TTK, Boutillon A, Rodriguez D, Lavilley V, Labouesse M. HMP-1/α-catenin promotes junctional mechanical integrity during morphogenesis. PLoS One 2018; 13:e0193279. [PMID: 29466456 PMCID: PMC5821396 DOI: 10.1371/journal.pone.0193279] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/07/2018] [Indexed: 12/13/2022] Open
Abstract
Adherens junctions (AJs) are key structures regulating tissue integrity and maintaining adhesion between cells. During morphogenesis, junctional proteins cooperate closely with the actomyosin network to drive cell movement and shape changes. How the junctions integrate the mechanical forces in space and in time during an in vivo morphogenetic event is still largely unknown, due to a lack of quantitative data. To address this issue, we inserted a functional Fluorescence Resonance Energy Transfer (FRET)-based force biosensor within HMP-1/α-catenin of Caenorhabditis elegans. We find that the tension exerted on HMP-1 has a cell-specific distribution, is actomyosin-dependent, but is regulated differently from the tension on the actin cortex during embryonic elongation. By using time-lapse analysis of mutants and tissue-specific rescue experiments, we confirm the role of VAB-9/Claudin as an actin bundle anchor. Nevertheless, the tension exerted on HMP-1 did not increase in the absence of VAB-9/Claudin, suggesting that HMP-1 activity is not upregulated to compensate for loss of VAB-9. Our data indicate that HMP-1 does not modulate HMR-1/E-cadherin turnover, is required to recruit junctional actin but not stress fiber-like actin bundles. Altogether, our data suggest that HMP-1/α-catenin acts to promote the mechanical integrity of adherens junctions.
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Affiliation(s)
- Thanh Thi Kim Vuong-Brender
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire de Biologie du Développement—Institut de Biologie Paris Seine (LBD—IBPS), Paris, France
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, llkirch, France
| | - Arthur Boutillon
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire de Biologie du Développement—Institut de Biologie Paris Seine (LBD—IBPS), Paris, France
| | - David Rodriguez
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, llkirch, France
| | - Vincent Lavilley
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, llkirch, France
| | - Michel Labouesse
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire de Biologie du Développement—Institut de Biologie Paris Seine (LBD—IBPS), Paris, France
- Development and Stem Cells Program, IGBMC, CNRS (UMR7104), INSERM (U964), Université de Strasbourg, 1 rue Laurent Fries, llkirch, France
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29
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Muñoz-Jiménez C, Ayuso C, Dobrzynska A, Torres-Mendéz A, Ruiz PDLC, Askjaer P. An Efficient FLP-Based Toolkit for Spatiotemporal Control of Gene Expression in Caenorhabditis elegans. Genetics 2017; 206:1763-1778. [PMID: 28646043 PMCID: PMC5560786 DOI: 10.1534/genetics.117.201012] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/19/2017] [Indexed: 02/07/2023] Open
Abstract
Site-specific recombinases are potent tools to regulate gene expression. In particular, the Cre (cyclization recombination) and FLP (flipase) enzymes are widely used to either activate or inactivate genes in a precise spatiotemporal manner. Both recombinases work efficiently in the popular model organism Caenorhabditis elegans, but their use in this nematode is still only sporadic. To increase the utility of the FLP system in C. elegans, we have generated a series of single-copy transgenic strains that stably express an optimized version of FLP in specific tissues or by heat induction. We show that recombination efficiencies reach 100% in several cell types, such as muscles, intestine, and serotonin-producing neurons. Moreover, we demonstrate that most promoters drive recombination exclusively in the expected tissues. As examples of the potentials of the FLP lines, we describe novel tools for induced cell ablation by expression of the PEEL-1 toxin and a versatile FLP-out cassette for generation of GFP-tagged conditional knockout alleles. Together with other recombinase-based reagents created by the C. elegans community, this toolkit increases the possibilities for detailed analyses of specific biological processes at developmental stages inside intact animals.
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Affiliation(s)
- Celia Muñoz-Jiménez
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Cristina Ayuso
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Agnieszka Dobrzynska
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Antonio Torres-Mendéz
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Patricia de la Cruz Ruiz
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Peter Askjaer
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
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30
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A microRNA program in the C. elegans hypodermis couples to intestinal mTORC2/PQM-1 signaling to modulate fat transport. Genes Dev 2017; 30:1515-28. [PMID: 27401555 PMCID: PMC4949325 DOI: 10.1101/gad.283895.116] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 06/13/2016] [Indexed: 01/18/2023]
Abstract
In this study, Dowen et al. identified a microRNA-regulated developmental timing pathway that coordinates the mobilization of intestinal fat stores to the germline during C. elegans development. Their results show that lin-4 and let-7 microRNAs promotes mTOR signaling, which regulates intestinal fat metabolism, thereby providing insight into a novel function for microRNAs. Animals integrate metabolic, developmental, and environmental information before committing key resources to reproduction. In Caenorhabditis elegans, adult animals transport fat from intestinal cells to the germline to promote reproduction. We identified a microRNA (miRNA)-regulated developmental timing pathway that functions in the hypodermis to nonautonomously coordinate the mobilization of intestinal fat stores to the germline upon initiation of adulthood. This developmental timing pathway, which is controlled by the lin-4 and let-7 miRNAs, engages mTOR signaling in the intestine. The intestinal signaling component is specific to mTORC2 and functions in parallel to the insulin pathway to modulate the activity of the serum/glucocorticoid-regulated kinase (SGK-1). Surprisingly, SGK-1 functions independently of DAF-16/FoxO; instead, SGK-1 promotes the cytoplasmic localization of the PQM-1 transcription factor, which antagonizes intestinal fat mobilization at the transcriptional level when localized to the nucleus. These results revealed that a non-cell-autonomous developmental input regulates intestinal fat metabolism by engaging mTORC2 signaling to promote the intertissue transport of fat reserves from the soma to the germline.
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31
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The Bright Fluorescent Protein mNeonGreen Facilitates Protein Expression Analysis In Vivo. G3-GENES GENOMES GENETICS 2017; 7:607-615. [PMID: 28108553 PMCID: PMC5295605 DOI: 10.1534/g3.116.038133] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The Green Fluorescent Protein (GFP) has been tremendously useful in investigating cell architecture, protein localization, and protein function. Recent developments in transgenesis and genome editing methods now enable working with fewer transgene copies and, consequently, with physiological expression levels. However, lower signal intensity might become a limiting factor. The recently developed mNeonGreen protein is a brighter alternative to GFP in vitro. The goal of the present study was to determine how mNeonGreen performs in vivo in Caenorhabditis elegans—a model used extensively for fluorescence imaging in intact animals. We started with a side-by-side comparison between cytoplasmic forms of mNeonGreen and GFP expressed in the intestine, and in different neurons, of adult animals. While both proteins had similar photostability, mNeonGreen was systematically 3–5 times brighter than GFP. mNeonGreen was also used successfully to trace endogenous proteins, and label specific subcellular compartments such as the nucleus or the plasma membrane. To further demonstrate the utility of mNeonGreen, we tested transcriptional reporters for nine genes with unknown expression patterns. While mNeonGreen and GFP reporters gave overall similar expression patterns, low expression tissues were detected only with mNeonGreen. As a whole, our work establishes mNeonGreen as a brighter alternative to GFP for in vivo imaging in a multicellular organism. Furthermore, the present research illustrates the utility of mNeonGreen to tag proteins, mark subcellular regions, and describe new expression patterns, particularly in tissues with low expression.
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32
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Lockhead D, Schwarz EM, O'Hagan R, Bellotti S, Krieg M, Barr MM, Dunn AR, Sternberg PW, Goodman MB. The tubulin repertoire of C. elegans sensory neurons and its context-dependent role in process outgrowth. Mol Biol Cell 2016; 27:mbc.E16-06-0473. [PMID: 27654945 PMCID: PMC5170555 DOI: 10.1091/mbc.e16-06-0473] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 09/12/2016] [Accepted: 09/15/2016] [Indexed: 12/21/2022] Open
Abstract
Microtubules contribute to many cellular processes, including transport, signaling, and chromosome separation during cell division (Kapitein and Hoogenraad, 2015). They are comprised of αβ-tubulin heterodimers arranged into linear protofilaments and assembled into tubes. Eukaryotes express multiple tubulin isoforms (Gogonea et al., 1999), and there has been a longstanding debate as to whether the isoforms are redundant or perform specialized roles as part of a tubulin code (Fulton and Simpson, 1976). Here, we use the well-characterized touch receptor neurons (TRNs) of Caenorhabditis elegans to investigate this question, through genetic dissection of process outgrowth both in vivo and in vitro With single-cell RNA-seq, we compare transcription profiles for TRNs with those of two other sensory neurons, and present evidence that each sensory neuron expresses a distinct palette of tubulin genes. In the TRNs, we analyze process outgrowth and show that four tubulins (tba-1, tba-2, tbb-1, and tbb-2) function partially or fully redundantly, while two others (mec-7 and mec-12) perform specialized, context-dependent roles. Our findings support a model in which sensory neurons express overlapping subsets of tubulin genes whose functional redundancy varies between cell types and in vivo and in vitro contexts.
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Affiliation(s)
- Dean Lockhead
- *Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Erich M Schwarz
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Robert O'Hagan
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Sebastian Bellotti
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Michael Krieg
- *Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | - Maureen M Barr
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Paul W Sternberg
- Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Miriam B Goodman
- *Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
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33
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Mora-Lorca JA, Sáenz-Narciso B, Gaffney CJ, Naranjo-Galindo FJ, Pedrajas JR, Guerrero-Gómez D, Dobrzynska A, Askjaer P, Szewczyk NJ, Cabello J, Miranda-Vizuete A. Glutathione reductase gsr-1 is an essential gene required for Caenorhabditis elegans early embryonic development. Free Radic Biol Med 2016; 96:446-61. [PMID: 27117030 PMCID: PMC8386055 DOI: 10.1016/j.freeradbiomed.2016.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 04/18/2016] [Indexed: 12/22/2022]
Abstract
Glutathione is the most abundant thiol in the vast majority of organisms and is maintained in its reduced form by the flavoenzyme glutathione reductase. In this work, we describe the genetic and functional analysis of the Caenorhabditis elegans gsr-1 gene that encodes the only glutathione reductase protein in this model organism. By using green fluorescent protein reporters we demonstrate that gsr-1 produces two GSR-1 isoforms, one located in the cytoplasm and one in the mitochondria. gsr-1 loss of function mutants display a fully penetrant embryonic lethal phenotype characterized by a progressive and robust cell division delay accompanied by an aberrant distribution of interphasic chromatin in the periphery of the cell nucleus. Maternally expressed GSR-1 is sufficient to support embryonic development but these animals are short-lived, sensitized to chemical stress, have increased mitochondrial fragmentation and lower mitochondrial DNA content. Furthermore, the embryonic lethality of gsr-1 worms is prevented by restoring GSR-1 activity in the cytoplasm but not in mitochondria. Given the fact that the thioredoxin redox systems are dispensable in C. elegans, our data support a prominent role of the glutathione reductase/glutathione pathway in maintaining redox homeostasis in the nematode.
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Affiliation(s)
- José Antonio Mora-Lorca
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Sevilla, Spain; Departamento de Farmacología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain
| | | | - Christopher J Gaffney
- MRC/ARUK Centre for Musculoskeletal Ageing Research, University of Nottingham and Medical School Royal Derby Hospital, DE22 3DT Derby, United Kingdom
| | - Francisco José Naranjo-Galindo
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Sevilla, Spain
| | - José Rafael Pedrajas
- Grupo de Bioquímica y Señalización Celular, Departamento de Biología Experimental, Universidad de Jaén, 23071 Jaén, Spain
| | - David Guerrero-Gómez
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Sevilla, Spain
| | - Agnieszka Dobrzynska
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Peter Askjaer
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Nathaniel J Szewczyk
- MRC/ARUK Centre for Musculoskeletal Ageing Research, University of Nottingham and Medical School Royal Derby Hospital, DE22 3DT Derby, United Kingdom
| | - Juan Cabello
- Center for Biomedical Research of La Rioja (CIBIR), 26006 Logroño, Spain.
| | - Antonio Miranda-Vizuete
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41013 Sevilla, Spain.
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34
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Joshi KK, Matlack TL, Rongo C. Dopamine signaling promotes the xenobiotic stress response and protein homeostasis. EMBO J 2016; 35:1885-901. [PMID: 27261197 DOI: 10.15252/embj.201592524] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 05/03/2016] [Indexed: 01/11/2023] Open
Abstract
Multicellular organisms encounter environmental conditions that adversely affect protein homeostasis (proteostasis), including extreme temperatures, toxins, and pathogens. It is unclear how they use sensory signaling to detect adverse conditions and then activate stress response pathways so as to offset potential damage. Here, we show that dopaminergic mechanosensory neurons in C. elegans release the neurohormone dopamine to promote proteostasis in epithelia. Signaling through the DA receptor DOP-1 activates the expression of xenobiotic stress response genes involved in pathogenic resistance and toxin removal, and these genes are required for the removal of unstable proteins in epithelia. Exposure to a bacterial pathogen (Pseudomonas aeruginosa) results in elevated removal of unstable proteins in epithelia, and this enhancement requires DA signaling. In the absence of DA signaling, nematodes show increased sensitivity to pathogenic bacteria and heat-shock stress. Our results suggest that dopaminergic sensory neurons, in addition to slowing down locomotion upon sensing a potential bacterial feeding source, also signal to frontline epithelia to activate the xenobiotic stress response so as to maintain proteostasis and prepare for possible infection.
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Affiliation(s)
- Kishore K Joshi
- Department of Genetics, The Waksman Institute Rutgers The State University of New Jersey, Piscataway, NJ, USA
| | - Tarmie L Matlack
- Department of Genetics, The Waksman Institute Rutgers The State University of New Jersey, Piscataway, NJ, USA
| | - Christopher Rongo
- Department of Genetics, The Waksman Institute Rutgers The State University of New Jersey, Piscataway, NJ, USA
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35
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Zou W, Yadav S, DeVault L, Jan YN, Sherwood DR. RAB-10-Dependent Membrane Transport Is Required for Dendrite Arborization. PLoS Genet 2015; 11:e1005484. [PMID: 26394140 PMCID: PMC4578882 DOI: 10.1371/journal.pgen.1005484] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 08/05/2015] [Indexed: 01/07/2023] Open
Abstract
Formation of elaborately branched dendrites is necessary for the proper input and connectivity of many sensory neurons. Previous studies have revealed that dendritic growth relies heavily on ER-to-Golgi transport, Golgi outposts and endocytic recycling. How new membrane and associated cargo is delivered from the secretory and endosomal compartments to sites of active dendritic growth, however, remains unknown. Using a candidate-based genetic screen in C. elegans, we have identified the small GTPase RAB-10 as a key regulator of membrane trafficking during dendrite morphogenesis. Loss of rab-10 severely reduced proximal dendritic arborization in the multi-dendritic PVD neuron. RAB-10 acts cell-autonomously in the PVD neuron and localizes to the Golgi and early endosomes. Loss of function mutations of the exocyst complex components exoc-8 and sec-8, which regulate tethering, docking and fusion of transport vesicles at the plasma membrane, also caused proximal dendritic arborization defects and led to the accumulation of intracellular RAB-10 vesicles. In rab-10 and exoc-8 mutants, the trans-membrane proteins DMA-1 and HPO-30, which promote PVD dendrite stabilization and branching, no longer localized strongly to the proximal dendritic membranes and instead were sequestered within intracellular vesicles. Together these results suggest a crucial role for the Rab10 GTPase and the exocyst complex in controlling membrane transport from the secretory and/or endosomal compartments that is required for dendritic growth. Dendrites are cellular extensions from neurons that gather information from other neurons or cues from the external environment to convey to the nervous system of an organism. Dendrites are often extensively branched, raising the question of how neurons supply plasma membrane and dendrite specific proteins from the source of synthesis inside the cell to developing dendrites. We have examined membrane trafficking in the PVD neuron in the nematode worm C. elegans to investigate how new membrane and dendrite proteins are trafficked. The PVD neuron is easy to visualize and has remarkably long and widely branched dendrites positioned along the skin of the worm, which transmits information about harsh touch and cold temperature to the nervous system. We have discovered that a key organizer of vesicle trafficking, the RAB-10 protein, localizes to membrane vesicles and is required to traffic these vesicles that contain plasma membrane and dendrite proteins to the growing PVD dendrite. Further, our work revealed that a complex of proteins, termed the exocyst, that helps fuse membrane vesicles at the plasma membrane, localizes with RAB-10 and is required for dendrite branching. Together, our work has revealed a novel mechanism for how neurons build dendrites that could be used to help repair damaged neurons in human diseases and during aging.
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Affiliation(s)
- Wei Zou
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Smita Yadav
- Howard Hughes Medical Institute, Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Laura DeVault
- Howard Hughes Medical Institute, Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - David R. Sherwood
- Department of Biology, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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Gorrepati L, Krause MW, Chen W, Brodigan TM, Correa-Mendez M, Eisenmann DM. Identification of Wnt Pathway Target Genes Regulating the Division and Differentiation of Larval Seam Cells and Vulval Precursor Cells in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2015; 5:1551-66. [PMID: 26048561 PMCID: PMC4528312 DOI: 10.1534/g3.115.017715] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/18/2015] [Indexed: 12/29/2022]
Abstract
The evolutionarily conserved Wnt/β-catenin signaling pathway plays a fundamental role during metazoan development, regulating numerous processes including cell fate specification, cell migration, and stem cell renewal. Wnt ligand binding leads to stabilization of the transcriptional effector β-catenin and upregulation of target gene expression to mediate a cellular response. During larval development of the nematode Caenorhabditis elegans, Wnt/β-catenin pathways act in fate specification of two hypodermal cell types, the ventral vulval precursor cells (VPCs) and the lateral seam cells. Because little is known about targets of the Wnt signaling pathways acting during larval VPC and seam cell differentiation, we sought to identify genes regulated by Wnt signaling in these two hypodermal cell types. We conditionally activated Wnt signaling in larval animals and performed cell type-specific "mRNA tagging" to enrich for VPC and seam cell-specific mRNAs, and then used microarray analysis to examine gene expression compared to control animals. Two hundred thirty-nine genes activated in response to Wnt signaling were identified, and we characterized 50 genes further. The majority of these genes are expressed in seam and/or vulval lineages during normal development, and reduction of function for nine genes caused defects in the proper division, fate specification, fate execution, or differentiation of seam cells and vulval cells. Therefore, the combination of these techniques was successful at identifying potential cell type-specific Wnt pathway target genes from a small number of cells and at increasing our knowledge of the specification and behavior of these C. elegans larval hypodermal cells.
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Affiliation(s)
- Lakshmi Gorrepati
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | | | - Weiping Chen
- Intramural Research Program, NIDDK, Bethesda, Maryland 20814
| | | | - Margarita Correa-Mendez
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
| | - David M Eisenmann
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland 21250
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Entchev EV, Patel DS, Zhan M, Steele AJ, Lu H, Ch'ng Q. A gene-expression-based neural code for food abundance that modulates lifespan. eLife 2015; 4:e06259. [PMID: 25962853 PMCID: PMC4417936 DOI: 10.7554/elife.06259] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 04/03/2015] [Indexed: 12/18/2022] Open
Abstract
How the nervous system internally represents environmental food availability is poorly understood. Here, we show that quantitative information about food abundance is encoded by combinatorial neuron-specific gene-expression of conserved TGFβ and serotonin pathway components in Caenorhabditis elegans. Crosstalk and auto-regulation between these pathways alters the shape, dynamic range, and population variance of the gene-expression responses of daf-7 (TGFβ) and tph-1 (tryptophan hydroxylase) to food availability. These intricate regulatory features provide distinct mechanisms for TGFβ and serotonin signaling to tune the accuracy of this multi-neuron code: daf-7 primarily regulates gene-expression variability, while tph-1 primarily regulates the dynamic range of gene-expression responses. This code is functional because daf-7 and tph-1 mutations bidirectionally attenuate food level-dependent changes in lifespan. Our results reveal a neural code for food abundance and demonstrate that gene expression serves as an additional layer of information processing in the nervous system to control long-term physiology. DOI:http://dx.doi.org/10.7554/eLife.06259.001 To maximize their chances of survival, animals need to be able to sense changes in the abundance of food in their environment and respond in an appropriate manner. The nervous system is able to sense cues from the environment and coordinate responses in the whole organism, but it is not clear how this leads to long-term changes in the organism's biology. In nematode worms, two genes called daf-7 and tph-1 appear to be involved in connecting the sensing of food availability with changes in the biology of the organism. The daf-7 gene encodes a hormone, while tph-1 encodes an enzyme that makes a neurochemical called serotonin. Here, Entchev, Patel, Zhan et al. found that daf-7 and tph-1 genes are active in three pairs of neurons in nematode worms. The experiments show that these neurons collectively form a circuit that carries information about the abundance of food, which leads to changes in how long the worms live. When this circuit was disrupted by removing these genes, the worms' ability to adjust their lifespan in response to changes in the availability of food was weakened, likely because they were unable to sense food. The experiments also show that the circuit regulates itself, largely because daf-7 and tph-1 are able to control each-other's activity. Together, these results suggest that changing the activity of certain genes in neurons enables nematode worms to alter their biology in response to changes in the availability of food. Neurons in the brain use electrical activity to communicate and process information and Entchev, Patel, Zhan et al.'s findings imply that gene activity can also perform a similar role. DOI:http://dx.doi.org/10.7554/eLife.06259.002
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Affiliation(s)
- Eugeni V Entchev
- MRC Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Dhaval S Patel
- MRC Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Mei Zhan
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, United States
| | - Andrew J Steele
- MRC Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Hang Lu
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, United States
| | - QueeLim Ch'ng
- MRC Centre for Developmental Neurobiology, King's College London, London, United Kingdom
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Martín-Durán JM, Hejnol A. The study of Priapulus caudatus reveals conserved molecular patterning underlying different gut morphogenesis in the Ecdysozoa. BMC Biol 2015; 13:29. [PMID: 25895830 PMCID: PMC4434581 DOI: 10.1186/s12915-015-0139-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 04/13/2015] [Indexed: 12/14/2022] Open
Abstract
Background The digestive systems of animals can become highly specialized in response to their exploration and occupation of new ecological niches. Although studies on different animals have revealed commonalities in gut formation, the model systems Caenorhabditis elegans and Drosophila melanogaster, which belong to the invertebrate group Ecdysozoa, exhibit remarkable deviations in how their intestines develop. Their morphological and developmental idiosyncrasies have hindered reconstructions of ancestral gut characters for the Ecdysozoa, and limit comparisons with vertebrate models. In this respect, the phylogenetic position, and slow evolving morphological and molecular characters of marine priapulid worms advance them as a key group to decipher evolutionary events that occurred in the lineages leading to C. elegans and D. melanogaster. Results In the priapulid Priapulus caudatus, the gut consists of an ectodermal foregut and anus, and a mid region of at least partial endodermal origin. The inner gut develops into a 16-cell primordium devoid of visceral musculature, arranged in three mid tetrads and two posterior duplets. The mouth invaginates ventrally and shifts to a terminal anterior position as the ventral anterior ectoderm differentially proliferates. Contraction of the musculature occurs as the head region retracts into the trunk and resolves the definitive larval body plan. Despite obvious developmental differences with C. elegans and D. melanogaster, the expression in P. caudatus of the gut-related candidate genes NK2.1, foxQ2, FGF8/17/18, GATA456, HNF4, wnt1, and evx demonstrate three distinct evolutionarily conserved molecular profiles that correlate with morphologically identified sub-regions of the gut. Conclusions The comparative analysis of priapulid development suggests that a midgut formed by a single endodermal population of vegetal cells, a ventral mouth, and the blastoporal origin of the anus are ancestral features in the Ecdysozoa. Our molecular data on P. caudatus reveal a conserved ecdysozoan gut-patterning program and demonstrates that extreme morphological divergence has not been accompanied by major molecular innovations in transcriptional regulators during digestive system evolution in the Ecdysozoa. Our data help us understand the origins of the ecdysozoan body plan, including those of C. elegans and D. melanogaster, and this is critical for comparisons between these two prominent model systems and their vertebrate counterparts. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0139-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- José M Martín-Durán
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008, Bergen, Norway.
| | - Andreas Hejnol
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008, Bergen, Norway.
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Kagoshima H, Kohara Y. Co-expression of the transcription factors CEH-14 and TTX-1 regulates AFD neuron-specific genes gcy-8 and gcy-18 in C. elegans. Dev Biol 2015; 399:325-36. [PMID: 25614239 DOI: 10.1016/j.ydbio.2015.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 12/28/2014] [Accepted: 01/12/2015] [Indexed: 12/21/2022]
Abstract
A wide variety of cells are generated by the expression of characteristic sets of genes, primarily those regulated by cell-specific transcription. To elucidate the mechanism regulating cell-specific gene expression in a highly specialized cell, AFD thermosensory neuron in Caenorhabditis elegans, we analyzed the promoter sequences of guanylyl cyclase genes, gcy-8 and gcy-18, exclusively expressed in AFD. In this study, we showed that AFD-specific expression of gcy-8 and gcy-18 requires the co-expression of homeodomain proteins, CEH-14/LHX3 and TTX-1/OTX1. We observed that mutation of ttx-1 or ceh-14 caused a reduction in the expression of gcy-8 and gcy-18 and that the expression was completely lost in double mutants. This synergy effect was also observed with other AFD marker genes, such as ntc-1, nlp-21and cng-3. Electrophoretic mobility shift assays revealed direct interaction of CEH-14 and TTX-1 proteins with gcy-8 and gcy-18 promoters in vitro. The binding sites of CEH-14 and TTX-1 proteins were confirmed to be essential for AFD-specific expression of gcy-8 and gcy-18 in vivo. We also demonstrated that forced expression of CEH-14 and TTX-1 in AWB chemosensory neurons induced ectopic expression of gcy-8 and gcy-18 reporters in this neuron. Finally, we showed that the regulation of gcy-8 and gcy-18 expression by ceh-14 and ttx-1 is evolutionally conserved in five Caenorhabditis species. Taken together, ceh-14 and ttx-1 expression determines the fate of AFD as terminal selector genes at the final step of cell specification.
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Affiliation(s)
- Hiroshi Kagoshima
- Genome Biology Laboratory, Center for Genetic Resource Information, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan; Transdisciplinary Research Integration Center, Research Organization of Information and Systems (ROIS), Toranomon 4-3-13, Minato-ku, Tokyo 105-0001, Japan
| | - Yuji Kohara
- Genome Biology Laboratory, Center for Genetic Resource Information, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan.
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Schild LC, Zbinden L, Bell HW, Yu YV, Sengupta P, Goodman MB, Glauser DA. The balance between cytoplasmic and nuclear CaM kinase-1 signaling controls the operating range of noxious heat avoidance. Neuron 2014; 84:983-96. [PMID: 25467982 DOI: 10.1016/j.neuron.2014.10.039] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2014] [Indexed: 12/12/2022]
Abstract
Through encounters with predators, competitors, and noxious stimuli, animals have evolved defensive responses that minimize injury and are essential for survival. Physiological adaptation modulates the stimulus intensities that trigger such nocifensive behaviors, but the molecular networks that define their operating range are largely unknown. Here, we identify a gain-of-function allele of the cmk-1 CaMKI gene in C. elegans and show that loss of the regulatory domain of the CaMKI enzyme produces thermal analgesia and shifts the operating range for nocifensive heat avoidance to higher temperatures. Such analgesia depends on nuclear CMK-1 signaling, while cytoplasmic CMK-1 signaling lowers the threshold for thermal avoidance. CMK-1 acts downstream of heat detection in thermal receptor neurons and controls neuropeptide release. Our results establish CaMKI as a key regulator of the operating range for nocifensive behaviors and suggest strategies for producing thermal analgesia through the regulation of CaMKI-dependent signaling.
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Affiliation(s)
- Lisa C Schild
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Laurie Zbinden
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Harold W Bell
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Yanxun V Yu
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Piali Sengupta
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford School of Medicine, Stanford, CA 94305, USA.
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Reid A, Yücel D, Wood M, Llamosas E, Kant S, Crossley M, Nicholas H. The transcriptional repressor CTBP-1 functions in the nervous system of Caenorhabditis elegans to regulate lifespan. Exp Gerontol 2014; 60:153-65. [PMID: 25456848 DOI: 10.1016/j.exger.2014.09.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 09/11/2014] [Accepted: 09/13/2014] [Indexed: 01/08/2023]
Abstract
C-terminal binding proteins (CtBPs) are recruited by a variety of transcription factors to mediate gene repression. Nematode CTBP-1 has previously been shown to play a role in the regulation of lifespan; Caenorhabditis elegans strains carrying a deletion in the ctbp-1 gene showed a 10-20% increase in mean and maximal lifespan compared with wild-type control strains. We set out to identify the tissues in which CTBP-1 functions to regulate lifespan in C. elegans. Our analysis of reporter genes shows that CTBP-1 is predominantly expressed in the nervous system with lower levels detectable in the hypodermis. Tissue-specific rescue experiments demonstrated that CTBP-1 functions in the nervous system to regulate lifespan. Previously, the lifespan extension in a ctbp-1 mutant was attributed, at least in part, to the misregulation of a lipase gene, lips-7. We therefore focussed on lips-7 and found that expressing CTBP-1 solely in the nervous system of a ctbp-1 mutant significantly reduced lips-7 transcription. In addition, we studied another ctbp-1 mutant allele that also displayed a long-lived phenotype. In this case, lips-7 expression was unaffected. This observation argues that, while lips-7 may play a role in lifespan, its de-repression is not essential for the extension of lifespan phenotype. We show that a prominent site of LIPS-7 expression is the hypodermis, one of the sites of fat storage in C. elegans. Interestingly, we did not observe co-localisation of CTBP-1 and lips-7 transcription in the nervous system, indicating that CTBP-1 may be acting indirectly, in a cell non-autonomous manner. In summary, our data confirm that CTBP-1 is involved in the regulation of lips-7 transcription but suggest that it may perform additional roles in the nervous system that contribute to the regulation of longevity.
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Affiliation(s)
- Anna Reid
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Duygu Yücel
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Mallory Wood
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Estelle Llamosas
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Sashi Kant
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Merlin Crossley
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, NSW 2052, Australia
| | - Hannah Nicholas
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia.
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Abstract
Food is critical for survival. Many animals, including the nematode Caenorhabditis elegans, use sensorimotor systems to detect and locate preferred food sources. However, the signaling mechanisms underlying food-choice behaviors are poorly understood. Here, we characterize the molecular signaling that regulates recognition and preference between different food odors in C. elegans. We show that the major olfactory sensory neurons, AWB and AWC, play essential roles in this behavior. A canonical Gα-protein, together with guanylate cyclases and cGMP-gated channels, is needed for the recognition of food odors. The food-odor-evoked signal is transmitted via glutamatergic neurotransmission from AWC and through AMPA and kainate-like glutamate receptor subunits. In contrast, peptidergic signaling is required to generate preference between different food odors while being dispensable for the recognition of the odors. We show that this regulation is achieved by the neuropeptide NLP-9 produced in AWB, which acts with its putative receptor NPR-18, and by the neuropeptide NLP-1 produced in AWC. In addition, another set of sensory neurons inhibits food-odor preference. These mechanistic logics, together with a previously mapped neural circuit underlying food-odor preference, provide a functional network linking sensory response, transduction, and downstream receptors to process complex olfactory information and generate the appropriate behavioral decision essential for survival.
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Defects in the C. elegans acyl-CoA synthase, acs-3, and nuclear hormone receptor, nhr-25, cause sensitivity to distinct, but overlapping stresses. PLoS One 2014; 9:e92552. [PMID: 24651852 PMCID: PMC3961378 DOI: 10.1371/journal.pone.0092552] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 02/25/2014] [Indexed: 12/13/2022] Open
Abstract
Metazoan transcription factors control distinct networks of genes in specific tissues, yet understanding how these networks are integrated into physiology, development, and homeostasis remains challenging. Inactivation of the nuclear hormone receptor nhr-25 ameliorates developmental and metabolic phenotypes associated with loss of function of an acyl-CoA synthetase gene, acs-3. ACS-3 activity prevents aberrantly high NHR-25 activity. Here, we investigated this relationship further by examining gene expression patterns following acs-3 and nhr-25 inactivation. Unexpectedly, we found that the acs-3 mutation or nhr-25 RNAi resulted in similar transcriptomes with enrichment in innate immunity and stress response gene expression. Mutants of either gene exhibited distinct sensitivities to pathogens and environmental stresses. Only nhr-25 was required for wild-type levels of resistance to the bacterial pathogen P. aeruginosa and only acs-3 was required for wild-type levels of resistance to osmotic stress and the oxidative stress generator, juglone. Inactivation of either acs-3 or nhr-25 compromised lifespan and resistance to the fungal pathogen D. coniospora. Double mutants exhibited more severe defects in the lifespan and P. aeruginosa assays, but were similar to the single mutants in other assays. Finally, acs-3 mutants displayed defects in their epidermal surface barrier, potentially accounting for the observed sensitivities. Together, these data indicate that inactivation of either acs-3 or nhr-25 causes stress sensitivity and increased expression of innate immunity/stress genes, most likely by different mechanisms. Elevated expression of these immune/stress genes appears to abrogate the transcriptional signatures relevant to metabolism and development.
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Afonso MQL, de Lima LHF, Bleicher L. Residue correlation networks in nuclear receptors reflect functional specialization and the formation of the nematode-specific P-box. BMC Genomics 2013; 14 Suppl 6:S1. [PMID: 24564869 PMCID: PMC3908500 DOI: 10.1186/1471-2164-14-s6-s1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Nuclear receptors (NRs) are transcription factors which bind small hormones, whose evolutionary history and the presence of different functional surfaces makes them an interesting target for a correlation based analysis. Results Correlation analysis of ligand binding domains shows that correlated residue subsets arise from the differences between functional sites in different nuclear receptor subfamilies. For the DNA binding domain, particularly, the analysis shows that the main source of correlation comes from residues that regulate hormone response element specificity, and one of the conserved residue sub-sets arises due to the presence of an unusual sequence for the DNA binding motif known as P-box in nematodes, suggesting the existence of different DBD-DNA specificities in nuclear receptors. Conclusions We conclude that DNA specificity and functional surface specialization has independently driven nuclear receptor evolution, and suggest possible binding modes for the class of divergent nuclear receptors in nematodes.
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Chapman K, Holmes M, Seckl J. 11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action. Physiol Rev 2013; 93:1139-206. [PMID: 23899562 DOI: 10.1152/physrev.00020.2012] [Citation(s) in RCA: 562] [Impact Index Per Article: 51.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.
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Affiliation(s)
- Karen Chapman
- Endocrinology Unit, Centre for Cardiovascular Science, The Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
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Berber S, Llamosas E, Thaivalappil P, Boag PR, Crossley M, Nicholas HR. Homeodomain interacting protein kinase (HPK-1) is required in the soma for robust germline proliferation in C. elegans. Dev Dyn 2013; 242:1250-61. [PMID: 23904186 DOI: 10.1002/dvdy.24023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Tightly regulated pathways maintain the balance between proliferation and differentiation within stem cell populations. In Caenorhabditis elegans, the germline is the only tissue that is maintained by stem-like cells into adulthood. In the current study, we investigated the role played by a member of the Homeodomain interacting protein kinase (HIPK) family of serine/threonine kinases, HPK-1, in the development and maintenance of the C. elegans germline. RESULTS We report that HPK-1 is required for promotion of germline proliferation during development and into adulthood. Additionally, we show that HPK-1 is required in the soma for regulation of germline proliferation. We also show that HPK-1 is a predominantly nuclear protein expressed in several somatic tissues including germline-interacting somatic cells. CONCLUSIONS Our observations are consistent with a conserved role for HIPKs in the control of cellular proliferation and identify a new context for such control in germ cell proliferation.
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Affiliation(s)
- Slavica Berber
- School of Molecular Bioscience, University of Sydney, Sydney, Australia
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A neuronal signaling pathway of CaMKII and Gqα regulates experience-dependent transcription of tph-1. J Neurosci 2013; 33:925-35. [PMID: 23325232 DOI: 10.1523/jneurosci.2355-12.2013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dynamic serotonin biosynthesis is important for serotonin function; however, the mechanisms that underlie experience-dependent transcriptional regulation of the rate-limiting serotonin biosynthetic enzyme tryptophan hydroxylase (TPH) are poorly understood. Here, we characterize the molecular and cellular mechanisms that regulate increased transcription of Caenorhabditis elegans tph-1 in a pair of serotonergic neurons ADF during an aversive experience with pathogenic bacteria, a common environmental peril for worms. Training with pathogenic bacteria induces a learned aversion to the smell of the pathogen, a behavioral plasticity that depends on the serotonin signal from ADF neurons. We demonstrate that pathogen training increases ADF neuronal activity. While activating ADF increases tph-1 transcription, inhibiting ADF activity abolishes the training effect on tph-1, demonstrating the dependence of tph-1 transcriptional regulation on ADF neural activity. At the molecular level, the C. elegans homolog of CaMKII, UNC-43, functions cell-autonomously in ADF neurons to generate training-dependent enhancement in neuronal activity and tph-1 transcription, and this cell-autonomous function of UNC-43 is required for learning. Furthermore, selective expression of an activated form of UNC-43 in ADF neurons is sufficient to increase ADF activity and tph-1 transcription, mimicking the training effect. Upstream of ADF, the Gqα protein EGL-30 facilitates training-dependent induction of tph-1 by functional regulation of olfactory sensory neurons, which underscores the importance of sensory experience. Together, our work elucidates the molecular and cellular mechanisms whereby experience modulates tph-1 transcription.
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Van Nostrand EL, Kim SK. Integrative analysis of C. elegans modENCODE ChIP-seq data sets to infer gene regulatory interactions. Genome Res 2013; 23:941-53. [PMID: 23531767 PMCID: PMC3668362 DOI: 10.1101/gr.152876.112] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The C. elegans modENCODE Consortium has defined in vivo binding sites for a large array of transcription factors by ChIP-seq. In this article, we present examples that illustrate how this compendium of ChIP-seq data can drive biological insights not possible with analysis of individual factors. First, we analyze the number of independent factors bound to the same locus, termed transcription factor complexity, and find that low-complexity sites are more likely to respond to altered expression of a single bound transcription factor. Next, we show that comparison of binding sites for the same factor across developmental stages can reveal insight into the regulatory network of that factor, as we find that the transcription factor UNC-62 has distinct binding profiles at different stages due to distinct cofactor co-association as well as tissue-specific alternative splicing. Finally, we describe an approach to infer potential regulators of gene expression changes found in profiling experiments (such as DNA microarrays) by screening these altered genes to identify significant enrichment for targets of a transcription factor identified in ChIP-seq data sets. After confirming that this approach can correctly identify the upstream regulator on expression data sets for which the regulator was previously known, we applied this approach to identify novel candidate regulators of transcriptional changes with age. The analysis revealed nine candidate aging regulators, of which three were previously known to have a role in longevity. We experimentally showed that two of the new candidate aging regulators can extend lifespan when overexpressed, indicating that this approach can identify novel functional regulators of complex processes.
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Affiliation(s)
- Eric L Van Nostrand
- Department of Genetics and Department of Developmental Biology, Stanford University Medical Center, Stanford, California 94305, USA
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He C, Lee JI, L'etoile N, O'Halloran D. A molecular readout of long-term olfactory adaptation in C. elegans. J Vis Exp 2012:4443. [PMID: 23287821 DOI: 10.3791/4443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps shape attention and also protects cells from over-stimulation. Adaptation within the olfactory circuit of C. elegans was first described by Colbert and Bargmann(1,2). Here, the authors defined parameters of the olfactory adaptation paradigm, which they used to design a genetic screen to isolate mutants defective in their ability to adapt to volatile odors sensed by the Amphid Wing cells type C (AWC) sensory neurons. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor(3) for 30 min they will adapt their responsiveness to the odor and will then ignore the adapting odor in a chemotaxis behavioral assay for ~1 hr. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor for ~1 hr they will then ignore the adapting odor in a chemotaxis behavioral assay for ~3 hr. These two phases of olfactory adaptation in C. elegans were described as short-term olfactory adaptation (induced after 30 min odor exposure), and long-term olfactory adaptation (induced after 60 min odor exposure). Later work from L'Etoile et al.,(4) uncovered a Protein Kinase G (PKG) called EGL-4 that is required for both the short-term and long-term olfactory adaptation in AWC neurons. The EGL-4 protein contains a nuclear localization sequence that is necessary for long-term olfactory adaptation responses but dispensable for short-term olfactory adaptation responses in the AWC(4). By tagging EGL-4 with a green fluorescent protein, it was possible to visualize the localization of EGL-4 in the AWC during prolonged odor exposure. Using this fully functional GFP-tagged EGL-4 (GFP::EGL-4) molecule we have been able to develop a molecular readout of long-term olfactory adaptation in the AWC(5). Using this molecular readout of olfactory adaptation we have been able to perform both forward and reverse genetic screens to identify mutant animals that exhibit defective subcellular localization patterns of GFP::EGL-4 in the AWC(6,7). Here we describe: 1) the construction of GFP::EGL-4 expressing animals; 2) the protocol for cultivation of animals for long-term odor-induced nuclear translocation assays; and 3) the scoring of the long-term odor-induced nuclear translocation event and recovery (re-sensitization) from the nuclear GFP::EGL-4 state.
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Affiliation(s)
- Chao He
- Department of Biological Sciences and Institute for Neuroscience, George Washington University
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Xie M, Roy R. Increased levels of hydrogen peroxide induce a HIF-1-dependent modification of lipid metabolism in AMPK compromised C. elegans dauer larvae. Cell Metab 2012; 16:322-35. [PMID: 22921415 DOI: 10.1016/j.cmet.2012.07.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 06/05/2012] [Accepted: 07/13/2012] [Indexed: 10/28/2022]
Abstract
Cells have evolved numerous mechanisms to circumvent stresses caused by the environment, and many of them are regulated by the AMP-activated kinase (AMPK). Unlike most organisms, C. elegans AMPK-null mutants are viable, but they die prematurely in the "long-lived" dauer stage due to exhaustion of triglyceride stores. Using a genome-wide RNAi approach, we demonstrate that the disruption of genes that increase hydrogen peroxide levels enhance the survival of AMPK mutant dauers by altering both the abundance and the nature of the fatty-acid content in the animal by increasing the HIF-1-dependent expression of several key enzymes involved in fatty-acid biosynthesis. Our data provide a mechanistic foundation to explain how an optimal level of an often vilified ROS-generating compound such as hydrogen peroxide can provide cellular benefit, a phenomenon described as hormesis, by instructing cells to readjust their lipid biosynthetic capacity through downstream HIF-1 activation to correct cellular energy deficiencies.
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Affiliation(s)
- Meng Xie
- Developmental Biology Research Initiative, Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, QC H3A 1B1, Canada
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