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Llense F, Ferraro T, Yang X, Song H, Labouesse M. Muscle and intestine innexins with muscle DEG/ENaC channels promote muscle coordination and embryo elongation in C. elegans. Development 2025; 152:dev204242. [PMID: 40151885 DOI: 10.1242/dev.204242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Accepted: 03/19/2025] [Indexed: 03/29/2025]
Abstract
Body axis elongation represents a fundamental morphogenetic process in development, which involves cell shape changes powered by mechanical forces. How mechanically interconnected tissues coordinate during organismal development remains largely unexplored. During Caenorhabditis elegans elongation, cyclic forces generated by muscle contractions induce remodeling of adherens junctions and the actin cytoskeleton in the epidermis, facilitating gradual embryo lengthening. Although previous studies have identified key players in epidermal cells, understanding how muscle cells coordinate their activity for proper embryo elongation remains unsolved. Using a calcium sensor to monitor muscle activity during elongation, we identified two cells in each muscle quadrant with a leader cell function that orchestrate muscle activity within their respective quadrants. Strikingly, ablation of these cells halted muscle contractions and delayed elongation. A targeted RNA interference screen focusing on communication channels identified two innexins and two DEG/ENaC channels regulating muscle activity, which proved to be required for normal embryonic elongation. Interestingly, one innexin exhibited specific expression in intestinal cells. Our findings provide insights into how embryonic body wall muscles coordinate their activity and how interconnected tissues ensure proper morphogenesis.
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Affiliation(s)
- Flora Llense
- Laboratoire Développement, Adaptation et Vieillissement, Sorbonne Université, IBPS, Dev2A, CNRS UMR8263 - Inserm U1345, 7 Quai St-Bernard, 75005 Paris, France
| | - Teresa Ferraro
- Laboratoire Développement, Adaptation et Vieillissement, Sorbonne Université, IBPS, Dev2A, CNRS UMR8263 - Inserm U1345, 7 Quai St-Bernard, 75005 Paris, France
| | - Xinyi Yang
- Laboratoire Développement, Adaptation et Vieillissement, Sorbonne Université, IBPS, Dev2A, CNRS UMR8263 - Inserm U1345, 7 Quai St-Bernard, 75005 Paris, France
| | - Hanla Song
- Laboratoire Développement, Adaptation et Vieillissement, Sorbonne Université, IBPS, Dev2A, CNRS UMR8263 - Inserm U1345, 7 Quai St-Bernard, 75005 Paris, France
| | - Michel Labouesse
- Laboratoire Développement, Adaptation et Vieillissement, Sorbonne Université, IBPS, Dev2A, CNRS UMR8263 - Inserm U1345, 7 Quai St-Bernard, 75005 Paris, France
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2
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Sojka SE, Ezak MJ, Polk EA, Bischer AP, Neyland KE, Wojtovich AP, Ferkey DM. An Extensive Gap Junction Neural Network Modulates Caenorhabditis elegans Aversive Behavior. Genes (Basel) 2025; 16:260. [PMID: 40149412 PMCID: PMC11941935 DOI: 10.3390/genes16030260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2025] [Revised: 02/17/2025] [Accepted: 02/18/2025] [Indexed: 03/29/2025] Open
Abstract
BACKGROUND/OBJECTIVES Caenorhabditis elegans rely on sensory perception of environmental cues for survival in their native soil and compost habitats. These cues provide information about nutrient availability, mating partners, or predatory and hazardous beacons. In C. elegans, the two bilaterally-symmetric head sensory neurons termed ASH are the main detectors of aversive nociceptive signals. Through their downstream connections in the nervous system, ASH activation causes the animal to initiate backward locomotion to escape and avoid the harmful stimulus. Modulation of avoidance behavior allows for situation-appropriate sensitivity and response to stimuli. We previously reported a role for gap junctions in the transport of regulatory cGMP to the ASHs where it functions to dampen avoidance responses. METHODS Here, we used genetic mutants and a combination of cell-selective rescue and knockdown experiments to identify gap junction proteins (innexins) involved in modulating ASH-mediated nociceptive behavioral responses. RESULTS We have characterized six additional C. elegans innexins that have overlapping and distinct roles within this regulatory network: INX-7, INX-15, INX-16, INX-17, UNC-7, and UNC-9. CONCLUSIONS This work expands our understanding of the extent to which ASH sensitivity can be tuned in a non-cell-autonomous manner.
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Affiliation(s)
- Savannah E. Sojka
- Ferkey Laboratory, Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Meredith J. Ezak
- Ferkey Laboratory, Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Emily A. Polk
- Ferkey Laboratory, Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
| | - Andrew P. Bischer
- Wojtovich Laboratory, Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Katherine E. Neyland
- Wojtovich Laboratory, Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Andrew P. Wojtovich
- Wojtovich Laboratory, Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Denise M. Ferkey
- Ferkey Laboratory, Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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3
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Khan H, Huang X, Raj V, Wang H. A versatile site-directed gene trap strategy to manipulate gene activity and control gene expression in Caenorhabditis elegans. PLoS Genet 2025; 21:e1011541. [PMID: 39841730 PMCID: PMC11753634 DOI: 10.1371/journal.pgen.1011541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2024] [Accepted: 12/15/2024] [Indexed: 01/24/2025] Open
Abstract
The ability to manipulate gene activity and control transgene expression is essential to study gene function. While several genetic tools for modifying genes or controlling expression separately are available for Caenorhabditis elegans, there are no genetic approaches to generate mutations that simultaneously disrupt gene function and provide genetic access to the cells expressing the disrupted gene. To achieve this, we developed a versatile gene trap strategy based on cGAL, a GAL4-UAS bipartite expression system for C. elegans. We designed a cGAL gene trap cassette and used CRISPR/Cas9 to insert it into the target gene, creating a bicistronic operon that simultaneously expresses a truncated endogenous protein and the cGAL driver in the cells expressing the target gene. We demonstrate that our cGAL gene trap strategy robustly generated loss-of-function alleles. Combining the cGAL gene trap lines with different UAS effector strains allowed us to rescue the loss-of-function phenotype, observe the gene expression pattern, and manipulate cell activity spatiotemporally. We show that, by recombinase-mediated cassette exchange (RMCE) via microinjection or genetic crossing, the cGAL gene trap lines can be further engineered in vivo to easily swap cGAL with other bipartite expression systems' drivers, including QF/QF2, Tet-On/Tet-Off, and LexA, to generate new gene trap lines with different drivers at the same genomic locus. These drivers can be combined with their corresponding effectors for orthogonal transgenic control. Thus, our cGAL-based gene trap is versatile and represents a powerful genetic tool for gene function analysis in C. elegans, which will ultimately provide new insights into how genes in the genome control the biology of an organism.
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Affiliation(s)
- Haania Khan
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Xinyu Huang
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Genetics Training Program, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Vishnu Raj
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Han Wang
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Genetics Training Program, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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4
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Turmel-Couture S, Martel PO, Beaulieu L, Lechasseur X, Fotso Dzuna LV, Narbonne P. Bidirectional transfer of a small membrane-impermeable molecule between the Caenorhabditis elegans intestine and germline. J Biol Chem 2024; 300:107963. [PMID: 39510179 DOI: 10.1016/j.jbc.2024.107963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 10/22/2024] [Accepted: 10/24/2024] [Indexed: 11/15/2024] Open
Abstract
The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) is a positive regulator of cell proliferation often upregulated in cancer. Its Caenorhabditis elegans ortholog MPK-1 stimulates germline stem cell (GSC) proliferation nonautonomously from the intestine or somatic gonad. How MPK-1 can perform this task from either of these two tissues however remains unclear. We reasoned that somatic MPK-1 activity could lead to the generation of proproliferative small molecules that could transfer from the intestine and/or somatic gonad to the germline. Here, in support of this hypothesis, we demonstrate that a significant fraction of the small membrane-impermeable fluorescent molecule, 5-carboxyfluorescein, transfers to the germline after its microinjection in the animal's intestine. The larger part of this transfer targets oocytes and requires the germline receptor mediated endocytosis 2 (RME-2) yolk receptor. A minor quantity of the dye is however distributed independently from RME-2 and more widely in the animal, including the distal germline, gonadal sheath, coelomocytes, and hypodermis. We further show that the intestine-to-germline transfer efficiency of this RME-2 independent fraction does not vary together with GSC proliferation rates or MPK-1 activity. Therefore, if germline proliferation was influenced by small membrane-impermeable molecules generated in the intestine, it is unlikely that proliferation would be regulated at the level of molecule transfer rate. Finally, we show that conversely, a similar fraction of germline injected 5-carboxyfluorescein transfers to the intestine, demonstrating transfer bidirectionality. Altogether, our results establish the possibility of an intestine-to-germline signaling axis mediated by small membrane-impermeable molecules that could promote GSC proliferation cell nonautonomously downstream of MPK-1 activity.
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Affiliation(s)
- Sarah Turmel-Couture
- Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada
| | - Pier-Olivier Martel
- Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada
| | - Lucie Beaulieu
- Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada
| | - Xavier Lechasseur
- Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada
| | | | - Patrick Narbonne
- Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Quebec, Canada.
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Wang Z, Garcia F, Ehlers RU, Molina C. Dauer juvenile recovery transcriptome of two contrasting EMS mutants of the entomopathogenic nematode Heterorhabditis bacteriophora. World J Microbiol Biotechnol 2024; 40:128. [PMID: 38451353 DOI: 10.1007/s11274-024-03902-6] [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: 11/17/2023] [Accepted: 01/18/2024] [Indexed: 03/08/2024]
Abstract
The entomopathogenic nematode Heterorhabditis bacteriophora, symbiotically associated with enterobacteria of the genus Photorhabdus, is a biological control agent against many insect pests. Dauer Juveniles (DJ) of this nematode are produced in industrial-scale bioreactors up to 100 m3 in liquid culture processes lasting approximately 11 days. A high DJ yield (> 200,000 DJ·mL-1) determines the success of the process. To start the mass production, a DJ inoculum proceeding from a previous monoxenic culture is added to pre-cultured (24 h) Photorhabdus bacteria. Within minutes after contact with the bacteria, DJ are expected to perceive signals that trigger their further development (DJ recovery) to reproductive hermaphrodites. A rapid, synchronized, and high DJ recovery is a key factor for an efficient culture process. In case of low percentage of DJ recovery, the final DJ yield is drastically reduced, and the amount of non-desired stages (males and non-fertilized females) hinders the DJ harvest. In a preliminary work, a huge DJ recovery phenotypic variability in H. bacteriophora ethyl methanesulphonate (EMS) mutants was determined. In the present study, two EMS-mutant lines (M31 and M88) with high and low recovery phenotypes were analyzed concerning their differences in gene expression during the first hours of contact with Photorhabdus supernatant containing food signals triggering recovery. A snapshot (RNA-seq analysis) of their transcriptome was captured at 0.5, 1, 3 and 6 h after exposure. Transcripts (3060) with significant regulation changes were identified in the two lines. To analyze the RNA-seq data over time, we (1) divided the expression profiles into clusters of similar regulation, (2) identified over and under-represented gene ontology categories for each cluster, (3) identified Caenorhabditis elegans homologous genes with recovery-related function, and (4) combined the information with available single nucleotide polymorphism (SNP) data. We observed that the expression dynamics of the contrasting mutants (M31 and M88) differ the most within the first 3 h after Photorhabdus supernatant exposure, and during this time, genes related to changes in the DJ cuticle and molting are more active in the high-recovery line (M31). Comparing the gene expression of DJ exposed to the insect food signal in the haemolymph, genes related to host immunosuppressive factors were not found in DJ upon bacterial supernatant exposure. No link between the position of SNPs associated with high recovery and changes in gene expression was determined for genes with high differential expression. Concerning specific transcripts, nine H. bacteriophora gene models with differential expression are provided as candidate genes for further studies.
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Affiliation(s)
- Zhen Wang
- e-nema GmbH, Klausdorfer Str. 28-36, 24223, Schwentinental, Germany
- Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University Kiel, Hermann-Rodewald-Str. 4, 24118, Kiel, Germany
| | - Francisco Garcia
- e-nema GmbH, Klausdorfer Str. 28-36, 24223, Schwentinental, Germany
- Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University Kiel, Hermann-Rodewald-Str. 4, 24118, Kiel, Germany
| | - Ralf-Udo Ehlers
- Faculty of Agricultural and Nutritional Sciences, Christian-Albrechts-University Kiel, Hermann-Rodewald-Str. 4, 24118, Kiel, Germany
| | - Carlos Molina
- e-nema GmbH, Klausdorfer Str. 28-36, 24223, Schwentinental, Germany.
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Petsakou A, Liu Y, Liu Y, Comjean A, Hu Y, Perrimon N. Epithelial Ca 2+ waves triggered by enteric neurons heal the gut. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.14.553227. [PMID: 37645990 PMCID: PMC10461974 DOI: 10.1101/2023.08.14.553227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
A fundamental and unresolved question in regenerative biology is how tissues return to homeostasis after injury. Answering this question is essential for understanding the etiology of chronic disorders such as inflammatory bowel diseases and cancer. We used the Drosophila midgut to investigate this question and discovered that during regeneration a subpopulation of cholinergic enteric neurons triggers Ca2+ currents among enterocytes to promote return of the epithelium to homeostasis. Specifically, we found that down-regulation of the cholinergic enzyme Acetylcholinesterase in the epithelium enables acetylcholine from defined enteric neurons, referred as ARCENs, to activate nicotinic receptors in enterocytes found near ARCEN-innervations. This activation triggers high Ca2+ influx that spreads in the epithelium through Inx2/Inx7 gap junctions promoting enterocyte maturation followed by reduction of proliferation and inflammation. Disrupting this process causes chronic injury consisting of ion imbalance, Yki activation and increase of inflammatory cytokines together with hyperplasia, reminiscent of inflammatory bowel diseases. Altogether, we found that during gut regeneration the conserved cholinergic pathway facilitates epithelial Ca2+ waves that heal the intestinal epithelium. Our findings demonstrate nerve- and bioelectric-dependent intestinal regeneration which advance the current understanding of how a tissue returns to its homeostatic state after injury and could ultimately help existing therapeutics.
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Affiliation(s)
| | - Yifang Liu
- Department of Genetics, Harvard Medical School, Boston, USA
| | - Ying Liu
- Department of Genetics, Harvard Medical School, Boston, USA
| | - Aram Comjean
- Department of Genetics, Harvard Medical School, Boston, USA
| | - Yanhui Hu
- Department of Genetics, Harvard Medical School, Boston, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, USA
- Howard Hughes Medical Institute, Boston, USA
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7
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Laboy JT, Bonner J, Norman KR. DEC-7/SUSD2, a sushi domain-containing protein, regulates an ultradian behavior mediated by intestinal epithelial Ca 2+ oscillations in Caenorhabditis elegans. Am J Physiol Cell Physiol 2023; 324:C1158-C1170. [PMID: 37067458 PMCID: PMC10191124 DOI: 10.1152/ajpcell.00552.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 04/18/2023]
Abstract
In Caenorhabditis elegans, rhythmic posterior body wall muscle contractions mediate the highly regular defecation cycle. These contractions are regulated by inositol-1,4,5-trisphosphate (InsP3) receptor-dependent Ca2+ oscillations in intestinal epithelial cells. Here, we find that mutations in dec-7, which encodes the nematode ortholog of the human Sushi domain-containing 2 protein (SUSD2), lead to an increase in InsP3 receptor-dependent rhythmic posterior body wall muscle contractions. DEC-7 is highly expressed in the intestinal epithelia and localizes to the cell-cell junction. The increase in rhythmic activity caused by the loss of dec-7 is dependent on the innexin gap junction protein INX-16. Moreover, DEC-7 is required for the clustering of INX-16 to the cell-cell junction of the intestinal epithelia. We hypothesize that DEC-7/SUSD2 regulates INX-16 activity to mediate the rhythmic frequency of the defecation motor program. Thus, our data indicate a critical role of a phylogenetically conserved cell-cell junction protein in mediating an ultradian rhythm in the intestinal epithelia of C. elegans.NEW & NOTEWORTHY The conserved complement group protein DEC-7/SUSD2 acts at the apical cell-cell junction of C. elegans intestinal epithelia to mediate gap junction protein organization and function to facilitate a Ca2+ wave-regulated ultradian behavior.
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Affiliation(s)
- Jocelyn T Laboy
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York, United States
| | - Jennifer Bonner
- Department of Biology, Skidmore College, Saratoga Springs, New York, United States
| | - Kenneth R Norman
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, Albany, New York, United States
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8
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Bioelectric regulation of intestinal stem cells. Trends Cell Biol 2022:S0962-8924(22)00234-3. [PMID: 36396487 PMCID: PMC10183058 DOI: 10.1016/j.tcb.2022.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/21/2022] [Accepted: 10/24/2022] [Indexed: 11/17/2022]
Abstract
Proper regulation of ion balance across the intestinal epithelium is essential for physiological functions, while ion imbalance causes intestinal disorders with dire health consequences. Ion channels, pumps, and exchangers are vital for regulating ion movements (i.e., bioelectric currents) that control epithelial absorption and secretion. Recent in vivo studies used the Drosophila gut to identify conserved pathways that link regulators of Ca2+, Na+ and Cl- with intestinal stem cell (ISC) proliferation. These studies laid a foundation for using the Drosophila gut to identify conserved proliferative responses triggered by bioelectric regulators. Here, we review these studies, discuss their significance, as well as the advantages of using Drosophila to unravel conserved bioelectrically induced molecular pathways in the intestinal epithelium under physiological, pathophysiological, and regenerative conditions.
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9
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Kim AA, Nguyen A, Marchetti M, Du X, Montell DJ, Pruitt BL, O'Brien LE. Independently paced Ca2+ oscillations in progenitor and differentiated cells in an ex vivo epithelial organ. J Cell Sci 2022; 135:jcs260249. [PMID: 35722729 PMCID: PMC9450890 DOI: 10.1242/jcs.260249] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 11/22/2022] Open
Abstract
Cytosolic Ca2+ is a highly dynamic, tightly regulated and broadly conserved cellular signal. Ca2+ dynamics have been studied widely in cellular monocultures, yet organs in vivo comprise heterogeneous populations of stem and differentiated cells. Here, we examine Ca2+ dynamics in the adult Drosophila intestine, a self-renewing epithelial organ in which stem cells continuously produce daughters that differentiate into either enteroendocrine cells or enterocytes. Live imaging of whole organs ex vivo reveals that stem-cell daughters adopt strikingly distinct patterns of Ca2+ oscillations after differentiation: enteroendocrine cells exhibit single-cell Ca2+ oscillations, whereas enterocytes exhibit rhythmic, long-range Ca2+ waves. These multicellular waves do not propagate through immature progenitors (stem cells and enteroblasts), of which the oscillation frequency is approximately half that of enteroendocrine cells. Organ-scale inhibition of gap junctions eliminates Ca2+ oscillations in all cell types - even, intriguingly, in progenitor and enteroendocrine cells that are surrounded only by enterocytes. Our findings establish that cells adopt fate-specific modes of Ca2+ dynamics as they terminally differentiate and reveal that the oscillatory dynamics of different cell types in a single, coherent epithelium are paced independently.
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Affiliation(s)
- Anna A Kim
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Departments of Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106, USA
- Department of Materials Science and Engineering, Uppsala University, 75103 Uppsala, Sweden
| | - Amanda Nguyen
- Departments of Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Marco Marchetti
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - XinXin Du
- Center for Computational Biology, Flatiron Institute, New York, NY 10010, USA
| | - Denise J Montell
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Beth L Pruitt
- Departments of Mechanical Engineering and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106, USA
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | - Lucy Erin O'Brien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Chan-Zuckerberg Biohub, San Francisco, CA 94158, USA
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10
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Jiang J, Su Y, Zhang R, Li H, Tao L, Liu Q. C. elegans enteric motor neurons fire synchronized action potentials underlying the defecation motor program. Nat Commun 2022; 13:2783. [PMID: 35589790 PMCID: PMC9120479 DOI: 10.1038/s41467-022-30452-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
C. elegans neurons were thought to be non-spiking until our recent discovery of action potentials in the sensory neuron AWA; however, the extent to which the C. elegans nervous system relies on analog or digital coding is unclear. Here we show that the enteric motor neurons AVL and DVB fire synchronous all-or-none calcium-mediated action potentials following the intestinal pacemaker during the rhythmic C. elegans defecation behavior. AVL fires unusual compound action potentials with each depolarizing calcium spike mediated by UNC-2 followed by a hyperpolarizing potassium spike mediated by a repolarization-activated potassium channel EXP-2. Simultaneous behavior tracking and imaging in free-moving animals suggest that action potentials initiated in AVL propagate along its axon to activate precisely timed DVB action potentials through the INX-1 gap junction. This work identifies a novel circuit of spiking neurons in C. elegans that uses digital coding for long-distance communication and temporal synchronization underlying reliable behavioral rhythm.
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Affiliation(s)
- Jingyuan Jiang
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, 100871, China
| | - Yifan Su
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, 100871, China
| | - Ruilin Zhang
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, 100871, China
- Yuanpei College, Peking University, Beijing, 100871, China
| | - Haiwen Li
- LMAM, School of Mathematical Sciences, Peking University, Beijing, 100871, China
| | - Louis Tao
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, 100871, China
- Center for Quantitative Biology, Peking University, Beijing, 100871, China
| | - Qiang Liu
- Lulu and Anthony Wang Laboratory of Neural Circuits and Behavior, The Rockefeller University, New York, NY, 10065, USA.
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong SAR.
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11
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Guan L, Yang Y, Liang JJ, Miao Y, Shang AY, Wang B, Wang YC, Ding M. ERGIC2 and ERGIC3 regulate the ER-to-Golgi transport of gap junction proteins in metazoans. Traffic 2022; 23:140-157. [PMID: 34994051 DOI: 10.1111/tra.12830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/16/2021] [Accepted: 01/04/2022] [Indexed: 11/26/2022]
Abstract
The extremely dynamic life cycle of gap junction connections requires highly efficient intracellular trafficking system especially designed for gap junction proteins, but the underlying mechanisms are largely unknown. Here, we identified that the COPII-associated proteins ERGIC2 (ER-Golgi intermediate compartment) and ERGIC3 are specifically required for the efficient intracellular transport of gap junction proteins in both C. elegans and mice. In the absence of Ergic2 or Ergic3, gap junction proteins accumulate in the ER and Golgi apparatus and the size of endogenous gap junction plaques is reduced. Knocking out the Ergic2 or Ergic3 in mice results in heart enlargement and cardiac malfunction accompanied by reduced number and size of connexin 43 (Cx43) gap junctions. Invertebrates' gap junction protein innexins share no sequence similarity with vertebrates' connexins. However, ERGIC2 and ERGIC3 could bind to gap junction proteins in both worms and mice. Characterization of the highly specialized roles of ERGIC2 and ERGIC3 in metazoans reveals how the early secretory pathway could be adapted to facilitate the efficient transport for gap junction proteins in vivo. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Liying Guan
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yongzhi Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jing Jing Liang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yue Miao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ang Yang Shang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Baolei Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ying Chun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Mei Ding
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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12
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Orchard I, Leyria J, Al-Dailami A, Lange AB. Fluid Secretion by Malpighian Tubules of Rhodnius prolixus: Neuroendocrine Control With New Insights From a Transcriptome Analysis. Front Endocrinol (Lausanne) 2021; 12:722487. [PMID: 34512553 PMCID: PMC8426621 DOI: 10.3389/fendo.2021.722487] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/03/2021] [Indexed: 01/25/2023] Open
Abstract
Rhodnius prolixus (the kissing bug and a major vector of Chagas disease) is an obligate blood feeder that in the case of the fifth instar consumes up to 10 times its unfed body weight in a single 20-minute feed. A post-prandial diuresis is initiated, within minutes of the start of gorging, in order to lower the mass and concentrate the nutrients of the meal. Thus, R. prolixus rapidly excretes a fluid that is high in NaCl content and hypo-osmotic to the hemolymph, thereby eliminating 50% of the volume of the blood meal within 3 hours of gorging. In R. prolixus, as with other insects, the Malpighian tubules play a critical role in diuresis. Malpighian tubules are not innervated, and their fine control comes under the influence of the neuroendocrine system that releases amines and neuropeptides as diuretic or antidiuretic hormones. These hormones act upon the Malpighian tubules via a variety of G protein-coupled receptors linked to second messenger systems that influence ion transporters and aquaporins; thereby regulating fluid secretion. Much has been discovered about the control of diuresis in R. prolixus, and other model insects, using classical endocrinological studies. The post-genomic era, however, has brought new insights, identifying novel diuretic and antidiuretic hormone-signaling pathways whilst also validating many of the classical discoveries. This paper will focus on recent discoveries into the neuroendocrine control of the rapid post-prandial diuresis in R. prolixus, in order to emphasize new insights from a transcriptome analysis of Malpighian tubules taken from unfed and fed bugs.
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Affiliation(s)
- Ian Orchard
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
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13
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Bédécarrats A, Puygrenier L, Castro O'Byrne J, Lade Q, Simmers J, Nargeot R. Organelle calcium-derived voltage oscillations in pacemaker neurons drive the motor program for food-seeking behavior in Aplysia. eLife 2021; 10:68651. [PMID: 34190043 PMCID: PMC8263059 DOI: 10.7554/elife.68651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/29/2021] [Indexed: 12/13/2022] Open
Abstract
The expression of motivated behaviors depends on both external and internally arising neural stimuli, yet the intrinsic releasing mechanisms for such variably occurring behaviors remain elusive. In isolated nervous system preparations of Aplysia, we have found that irregularly expressed cycles of motor output underlying food-seeking behavior arise from regular membrane potential oscillations of varying magnitude in an identified pair of interneurons (B63) in the bilateral buccal ganglia. This rhythmic signal, which is specific to the B63 cells, is generated by organelle-derived intracellular calcium fluxes that activate voltage-independent plasma membrane channels. The resulting voltage oscillation spreads throughout a subset of gap junction-coupled buccal network neurons and by triggering plateau potential-mediated bursts in B63, can initiate motor output driving food-seeking action. Thus, an atypical neuronal pacemaker mechanism, based on rhythmic intracellular calcium store release and intercellular propagation, can act as an autonomous intrinsic releaser for the occurrence of a motivated behavior.
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Affiliation(s)
| | - Laura Puygrenier
- Univ. Bordeaux, INCIA, UMR 5287, F-33076 Bordeaux, Bordeaux, France
| | | | - Quentin Lade
- Univ. Bordeaux, INCIA, UMR 5287, F-33076 Bordeaux, Bordeaux, France
| | - John Simmers
- Univ. Bordeaux, INCIA, UMR 5287, F-33076 Bordeaux, Bordeaux, France
| | - Romuald Nargeot
- Univ. Bordeaux, INCIA, UMR 5287, F-33076 Bordeaux, Bordeaux, France
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14
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Choi U, Wang H, Hu M, Kim S, Sieburth D. Presynaptic coupling by electrical synapses coordinates a rhythmic behavior by synchronizing the activities of a neuron pair. Proc Natl Acad Sci U S A 2021; 118:e2022599118. [PMID: 33972428 PMCID: PMC8157971 DOI: 10.1073/pnas.2022599118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electrical synapses are specialized structures that mediate the flow of electrical currents between neurons and have well known roles in synchronizing the activities of neuronal populations, both by mediating the current transfer from more active to less active neurons and by shunting currents from active neurons to their less active neighbors. However, how these positive and negative functions of electrical synapses are coordinated to shape rhythmic synaptic outputs and behavior is not well understood. Here, using a combination of genetics, behavioral analysis, and live calcium imaging in Caenorhabditis elegans, we show that electrical synapses formed by the gap junction protein INX-1/innexin couple the presynaptic terminals of a pair of motor neurons (AVL and DVB) to synchronize their activation in response to a pacemaker signal. Live calcium imaging reveals that inx-1/innexin mutations lead to asynchronous activation of AVL and DVB, due, in part, to loss of AVL-mediated activation of DVB by the pacemaker. In addition, loss of inx-1 leads to the ectopic activation of DVB at inappropriate times during the cycle through the activation of the L-type voltage-gated calcium channel EGL-19. We propose that electrical synapses between AVL and DVB presynaptic terminals function to ensure the precise and robust execution of a specific step in a rhythmic behavior by both synchronizing the activities of presynaptic terminals in response to pacemaker signaling and by inhibiting their activation in between cycles when pacemaker signaling is low.
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Affiliation(s)
- Ukjin Choi
- Development, Stem Cell, and Regenerative Medicine Graduate Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033
| | - Han Wang
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033
| | - Mingxi Hu
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033
| | - Sungjin Kim
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033
| | - Derek Sieburth
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033;
- Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
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15
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Yang ZL, Chen JN, Lu YY, Lu M, Wan QL, Wu GS, Luo HR. Inositol polyphosphate multikinase IPMK-1 regulates development through IP3/calcium signaling in Caenorhabditis elegans. Cell Calcium 2020; 93:102327. [PMID: 33316585 DOI: 10.1016/j.ceca.2020.102327] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 01/17/2023]
Abstract
Inositol polyphosphate multikinase (IPMK) is a conserved protein that initiates the production of inositol phosphate intracellular messengers and is critical for regulating a variety of cellular processes. Here, we report that the C. elegans IPMK-1, which is homologous to the mammalian inositol polyphosphate multikinase, plays a crucial role in regulating rhythmic behavior and development. The deletion mutant ipmk-1(tm2687) displays a long defecation cycle period and retarded postembryonic growth. The expression of functional ipmk-1::GFP was detected in the pharyngeal muscles, amphid sheath cells, the intestine, excretory (canal) cells, proximal gonad, and spermatheca. The expression of IPMK-1 in the intestine was sufficient for the wild-type phenotype. The IP3-kinase activity of IPMK-1 is required for defecation rhythms and postembryonic development. The defective phenotypes of ipmk-1(tm2687) could be rescued by a loss-of-function mutation in type I inositol 5-phosphatase homolog (IPP-5) and improved by a supplemental Ca2+ in the medium. Our work demonstrates that IPMK-1 and the signaling molecule inositol triphosphate (IP3) pathway modulate rhythmic behaviors and development by dynamically regulating the concentration of intracellular Ca2+ in C. elegans. Advances in understanding the molecular regulation of Ca2+ homeostasis and regulation of organism development may lead to therapeutic strategies that modulate Ca2+ signaling to enhance function and counteract disease processes. Unraveling the physiological role of IPMK and the underlying functional mechanism in C. elegans would contribute to understanding the role of IPMK in other species, especially in mammals, and benefit further research on the involvement of IPMK in disease.
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Affiliation(s)
- Zhong-Lin Yang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Graduate University of the Chinese Academy of Science, Beijing, 100049, China
| | - Jian-Ning Chen
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Yu-Yang Lu
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Min Lu
- Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Qin-Li Wan
- The Center for Precision Medicine of First Affiliated Hospital, Biomedical Translational Research Institute, Jinan University, Guangzhou, Guangdong 510632, China
| | - Gui-Sheng Wu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
| | - Huai-Rong Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Science, Kunming, Yunnan 650201, China; Graduate University of the Chinese Academy of Science, Beijing, 100049, China; Key Laboratory for Aging and Regenerative Medicine, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
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16
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Dere D, Zlomuzica A, Dere E. Channels to consciousness: a possible role of gap junctions in consciousness. Rev Neurosci 2020; 32:/j/revneuro.ahead-of-print/revneuro-2020-0012/revneuro-2020-0012.xml. [PMID: 32853172 DOI: 10.1515/revneuro-2020-0012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/26/2020] [Indexed: 12/20/2022]
Abstract
The neurophysiological basis of consciousness is still unknown and one of the most challenging questions in the field of neuroscience and related disciplines. We propose that consciousness is characterized by the maintenance of mental representations of internal and external stimuli for the execution of cognitive operations. Consciousness cannot exist without working memory, and it is likely that consciousness and working memory share the same neural substrates. Here, we present a novel psychological and neurophysiological framework that explains the role of consciousness for cognition, adaptive behavior, and everyday life. A hypothetical architecture of consciousness is presented that is organized as a system of operation and storage units named platforms that are controlled by a consciousness center (central executive/online platform). Platforms maintain mental representations or contents, are entrusted with different executive functions, and operate at different levels of consciousness. The model includes conscious-mode central executive/online and mental time travel platforms and semiconscious steady-state and preconscious standby platforms. Mental representations or contents are represented by neural circuits and their support cells (astrocytes, oligodendrocytes, etc.) and become conscious when neural circuits reverberate, that is, fire sequentially and continuously with relative synchronicity. Reverberatory activity in neural circuits may be initiated and maintained by pacemaker cells/neural circuit pulsars, enhanced electronic coupling via gap junctions, and unapposed hemichannel opening. The central executive/online platform controls which mental representations or contents should become conscious by recruiting pacemaker cells/neural network pulsars, the opening of hemichannels, and promoting enhanced neural circuit coupling via gap junctions.
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Affiliation(s)
- Dorothea Dere
- Département UMR 8256 Adaptation Biologique et Vieillissement, Sorbonne Université, Institut de Biologie Paris-Seine, (IBPS), UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris Cedex, France
| | - Armin Zlomuzica
- Faculty of Psychology, Behavioral and Clinical Neuroscience, University of Bochum, Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Département UMR 8256 Adaptation Biologique et Vieillissement, Sorbonne Université, Institut de Biologie Paris-Seine, (IBPS), UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris Cedex, France
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17
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Güiza J, Barría I, Sáez JC, Vega JL. Innexins: Expression, Regulation, and Functions. Front Physiol 2018; 9:1414. [PMID: 30364195 PMCID: PMC6193117 DOI: 10.3389/fphys.2018.01414] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/18/2018] [Indexed: 01/02/2023] Open
Abstract
The innexin (Inx) proteins form gap junction channels and non-junctional channels (named hemichannels) in invertebrates. These channels participate in cellular communication playing a relevant role in several physiological processes. Pioneer studies conducted mainly in worms and flies have shown that innexins participate in embryo development and behavior. However, recent studies have elucidated new functions of innexins in Arthropoda, Nematoda, Annelida, and Cnidaria, such as immune response, and apoptosis. This review describes emerging data of possible new roles of innexins and summarizes the data available to date.
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Affiliation(s)
- Juan Güiza
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Iván Barría
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - José L Vega
- Laboratorio de Fisiología Experimental, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
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18
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Galimov ER, Pryor RE, Poole SE, Benedetto A, Pincus Z, Gems D. Coupling of Rigor Mortis and Intestinal Necrosis during C. elegans Organismal Death. Cell Rep 2018; 22:2730-2741. [PMID: 29514100 PMCID: PMC5863043 DOI: 10.1016/j.celrep.2018.02.050] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 12/22/2017] [Accepted: 02/12/2018] [Indexed: 11/04/2022] Open
Abstract
Organismal death is a process of systemic collapse whose mechanisms are less well understood than those of cell death. We previously reported that death in C. elegans is accompanied by a calcium-propagated wave of intestinal necrosis, marked by a wave of blue autofluorescence (death fluorescence). Here, we describe another feature of organismal death, a wave of body wall muscle contraction, or death contraction (DC). This phenomenon is accompanied by a wave of intramuscular Ca2+ release and, subsequently, of intestinal necrosis. Correlation of directions of the DC and intestinal necrosis waves implies coupling of these death processes. Long-lived insulin/IGF-1-signaling mutants show reduced DC and delayed intestinal necrosis, suggesting possible resistance to organismal death. DC resembles mammalian rigor mortis, a postmortem necrosis-related process in which Ca2+ influx promotes muscle hyper-contraction. In contrast to mammals, DC is an early rather than a late event in C. elegans organismal death. VIDEO ABSTRACT.
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Affiliation(s)
- Evgeniy R Galimov
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Rosina E Pryor
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Sarah E Poole
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK
| | - Alexandre Benedetto
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK; Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YW, UK
| | - Zachary Pincus
- Department of Genetics and Department of Developmental Biology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - David Gems
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK.
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19
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Barr MM, García LR, Portman DS. Sexual Dimorphism and Sex Differences in Caenorhabditis elegans Neuronal Development and Behavior. Genetics 2018; 208:909-935. [PMID: 29487147 PMCID: PMC5844341 DOI: 10.1534/genetics.117.300294] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 01/05/2018] [Indexed: 01/05/2023] Open
Abstract
As fundamental features of nearly all animal species, sexual dimorphisms and sex differences have particular relevance for the development and function of the nervous system. The unique advantages of the nematode Caenorhabditis elegans have allowed the neurobiology of sex to be studied at unprecedented scale, linking ultrastructure, molecular genetics, cell biology, development, neural circuit function, and behavior. Sex differences in the C. elegans nervous system encompass prominent anatomical dimorphisms as well as differences in physiology and connectivity. The influence of sex on behavior is just as diverse, with biological sex programming innate sex-specific behaviors and modifying many other aspects of neural circuit function. The study of these differences has provided important insights into mechanisms of neurogenesis, cell fate specification, and differentiation; synaptogenesis and connectivity; principles of circuit function, plasticity, and behavior; social communication; and many other areas of modern neurobiology.
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Affiliation(s)
- Maureen M Barr
- Department of Genetics, Rutgers University, Piscataway, New Jersey 08854-8082
| | - L Rene García
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, New York 14642
- Department of Neuroscience, University of Rochester, New York 14642
- Department of Biology, University of Rochester, New York 14642
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20
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Electrophysiology of the rhythmic defecation program in nematode Heterorhabditis megidis. Sci Rep 2017; 7:17834. [PMID: 29259280 PMCID: PMC5736584 DOI: 10.1038/s41598-017-18118-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 12/06/2017] [Indexed: 11/08/2022] Open
Abstract
The nervous system controls most rhythmic behaviors, with a remarkable exception. In Caenorhabditis elegans periodic defecation rhythm does not appear to involve the nervous system. Such oscillations are studied in detail with genetic and molecular biology tools. The small size of C. elegans cells impairs the use of standard electrophysiological methods. We studied a similar rhythmic pacemaker in the noticeably larger gut cells of Heterorhabditis megidis nematode. H. megidis defecation cycle is driven by a central pattern generator (CPG) associated with unusual all-or-none hyper-polarization “action potential”. The CPG cycle period depends on the membrane potential and CPG cycling also persisted in experiments where the membrane potential of gut cells was continuously clamped at steady voltage levels. The usual excitable tissue description does not include the endoderm or imply the generation of hyper-polarization spikes. The nematode gut cells activity calls for a reevaluation of the excitable cells definition.
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21
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A Calcium- and Diacylglycerol-Stimulated Protein Kinase C (PKC), Caenorhabditis elegans PKC-2, Links Thermal Signals to Learned Behavior by Acting in Sensory Neurons and Intestinal Cells. Mol Cell Biol 2017; 37:MCB.00192-17. [PMID: 28716951 DOI: 10.1128/mcb.00192-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/07/2017] [Indexed: 12/18/2022] Open
Abstract
Ca2+- and diacylglycerol (DAG)-activated protein kinase C (cPKC) promotes learning and behavioral plasticity. However, knowledge of in vivo regulation and exact functions of cPKCs that affect behavior is limited. We show that PKC-2, a Caenorhabditis elegans cPKC, is essential for a complex behavior, thermotaxis. C. elegans memorizes a nutrient-associated cultivation temperature (Tc ) and migrates along the Tc within a 17 to 25°C gradient. pkc-2 gene disruption abrogated thermotaxis; a PKC-2 transgene, driven by endogenous pkc-2 promoters, restored thermotaxis behavior in pkc-2-/- animals. Cell-specific manipulation of PKC-2 activity revealed that thermotaxis is controlled by cooperative PKC-2-mediated signaling in both AFD sensory neurons and intestinal cells. Cold-directed migration (cryophilic drive) precedes Tc tracking during thermotaxis. Analysis of temperature-directed behaviors elicited by persistent PKC-2 activation or inhibition in AFD (or intestine) disclosed that PKC-2 regulates initiation and duration of cryophilic drive. In AFD neurons, PKC-2 is a Ca2+ sensor and signal amplifier that operates downstream from cyclic GMP-gated cation channels and distal guanylate cyclases. UNC-18, which regulates neurotransmitter and neuropeptide release from synaptic vesicles, is a critical PKC-2 effector in AFD. UNC-18 variants, created by mutating Ser311 or Ser322, disrupt thermotaxis and suppress PKC-2-dependent cryophilic migration.
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22
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Hall DH. Gap junctions in C. elegans: Their roles in behavior and development. Dev Neurobiol 2017; 77:587-596. [PMID: 27294317 PMCID: PMC5412865 DOI: 10.1002/dneu.22408] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/08/2016] [Accepted: 06/08/2016] [Indexed: 01/07/2023]
Abstract
The nematode Caenorhabditis elegans utilizes gap junctions in different fashions in virtually all of its cells. This model animal has a surprisingly large number of innexin genes within its genome, and many nematode cell types can express multiple innexins at once, leading to the formation of diverse junction types and enough redundancy to limit the effect of single gene knockdowns on animal development or behavioral phenotypes. Here, we review the general properties of these junctions, their expression patterns, and their known roles in tissue development and in the animal's connectome. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 587-596, 2017.
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Affiliation(s)
- David H Hall
- Department of Neuroscience, Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx, New York, 10461
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23
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Caenorhabditis elegans Male Copulation Circuitry Incorporates Sex-Shared Defecation Components To Promote Intromission and Sperm Transfer. G3-GENES GENOMES GENETICS 2017; 7:647-662. [PMID: 28031243 PMCID: PMC5295609 DOI: 10.1534/g3.116.036756] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Sexual dimorphism can be achieved using a variety of mechanisms, including sex-specific circuits and sex-specific function of shared circuits, though how these work together to produce sexually dimorphic behaviors requires further investigation. Here, we explore how components of the sex-shared defecation circuitry are incorporated into the sex-specific male mating circuitry in Caenorhabditis elegans to produce successful copulation. Using behavioral studies, calcium imaging, and genetic manipulation, we show that aspects of the defecation system are coopted by the male copulatory circuitry to facilitate intromission and ejaculation. Similar to hermaphrodites, male defecation is initiated by an intestinal calcium wave, but circuit activity is coordinated differently during mating. In hermaphrodites, the tail neuron DVB promotes expulsion of gut contents through the release of the neurotransmitter GABA onto the anal depressor muscle. However, in the male, both neuron and muscle take on modified functions to promote successful copulation. Males require calcium-dependent activator protein for secretion (CAPS)/unc-31, a dense core vesicle exocytosis activator protein, in the DVB to regulate copulatory spicule insertion, while the anal depressor is remodeled to promote release of sperm into the hermaphrodite. This work shows how sex-shared circuitry is modified in multiple ways to contribute to sex-specific mating.
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24
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Dissection of neuronal gap junction circuits that regulate social behavior in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2017; 114:E1263-E1272. [PMID: 28143932 DOI: 10.1073/pnas.1621274114] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A hub-and-spoke circuit of neurons connected by gap junctions controls aggregation behavior and related behavioral responses to oxygen, pheromones, and food in Caenorhabditis elegans The molecular composition of the gap junctions connecting RMG hub neurons with sensory spoke neurons is unknown. We show here that the innexin gene unc-9 is required in RMG hub neurons to drive aggregation and related behaviors, indicating that UNC-9-containing gap junctions mediate RMG signaling. To dissect the circuit in detail, we developed methods to inhibit unc-9-based gap junctions with dominant-negative unc-1 transgenes. unc-1(dn) alters a stomatin-like protein that regulates unc-9 electrical signaling; its disruptive effects can be rescued by a constitutively active UNC-9::GFP protein, demonstrating specificity. Expression of unc-1(dn) in RMG hub neurons, ADL or ASK pheromone-sensing neurons, or URX oxygen-sensing neurons disrupts specific elements of aggregation-related behaviors. In ADL, unc-1(dn) has effects opposite to those of tetanus toxin light chain, separating the roles of ADL electrical and chemical synapses. These results reveal roles of gap junctions in a complex behavior at cellular resolution and provide a tool for similar exploration of other gap junction circuits.
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25
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Nagy S, Huang YC, Alkema MJ, Biron D. Caenorhabditis elegans exhibit a coupling between the defecation motor program and directed locomotion. Sci Rep 2015; 5:17174. [PMID: 26597056 PMCID: PMC4657007 DOI: 10.1038/srep17174] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/26/2015] [Indexed: 12/27/2022] Open
Abstract
Distinct motor programs can be coupled to refine the repertoire of behavior dynamics. However, mechanisms underlying such coupling are poorly understood. The defecation motor program (DMP) of C. elegans is composed of a succession of body contraction and expulsion steps, performed repeatedly with a period of 50-60 sec. We show that recurring patterns of directed locomotion are executed in tandem with, co-reset, and co-terminate with the DMP cycle. Calcium waves in the intestine and proton signaling were shown to regulate the DMP. We found that genetic manipulations affecting these calcium dynamics regulated the corresponding patterns of directed locomotion. Moreover, we observed the initiation of a recurring locomotion pattern 10 seconds prior to the posterior body contraction, suggesting that the synchronized motor program may initiate prior to the DMP. This study links two multi-step motor programs executed by C. elegans in synchrony, utilizing non-neuronal tissue to drive directed locomotion.
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Affiliation(s)
- Stanislav Nagy
- The Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL
| | - Yung-Chi Huang
- Department of Neurobiology, University of Ma ssachusetts Medical School, Worcester, MA
| | - Mark J Alkema
- Department of Neurobiology, University of Ma ssachusetts Medical School, Worcester, MA
| | - David Biron
- The Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL
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Saijoh Y, Viotti M, Hadjantonakis AK. Follow your gut: relaying information from the site of left-right symmetry breaking in the mouse. Genesis 2014; 52:503-14. [PMID: 24753065 DOI: 10.1002/dvg.22783] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/08/2014] [Accepted: 04/08/2014] [Indexed: 12/19/2022]
Abstract
A central unresolved question in the molecular cascade that drives establishment of left-right (LR) asymmetry in vertebrates are the mechanisms deployed to relay information between the midline site of symmetry-breaking and the tissues which will execute a program of asymmetric morphogenesis. The cells located between these two distant locations must provide the medium for signal relay. Of these, the gut endoderm is an attractive candidate tissue for signal transmission since it comprises the epithelium that lies between the node, where asymmetry originates, and the lateral plate, where asymmetry can first be detected. Here, focusing on the mouse as a model, we review our current understanding and entertain open questions concerning the relay of LR information from its origin.
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Affiliation(s)
- Yukio Saijoh
- Department of Neurobiology and Anatomy, The University of Utah, Salt Lake City, Utah
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Velasquez S, Eugenin EA. Role of Pannexin-1 hemichannels and purinergic receptors in the pathogenesis of human diseases. Front Physiol 2014; 5:96. [PMID: 24672487 PMCID: PMC3953678 DOI: 10.3389/fphys.2014.00096] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 02/24/2014] [Indexed: 12/20/2022] Open
Abstract
In the last decade several groups have determined the key role of hemichannels formed by pannexins or connexins, extracellular ATP and purinergic receptors in physiological and pathological conditions. Our work and the work of others, indicate that the opening of Pannexin-1 hemichannels and activation of purinergic receptors by extracellular ATP is essential for HIV infection, cellular migration, inflammation, atherosclerosis, stroke, and apoptosis. Thus, this review discusses the importance of purinergic receptors, Panx-1 hemichannels and extracellular ATP in the pathogenesis of several human diseases and their potential use to design novel therapeutic approaches.
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Affiliation(s)
- Stephani Velasquez
- Public Health Research Institute, Rutgers the State University of New Jersey Newark, NJ, USA ; Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey Newark, NJ, USA
| | - Eliseo A Eugenin
- Public Health Research Institute, Rutgers the State University of New Jersey Newark, NJ, USA ; Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey Newark, NJ, USA
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Simonsen KT, Moerman DG, Naus CC. Gap junctions in C. elegans. Front Physiol 2014; 5:40. [PMID: 24575048 PMCID: PMC3920094 DOI: 10.3389/fphys.2014.00040] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/20/2014] [Indexed: 11/26/2022] Open
Abstract
As in other multicellular organisms, the nematode Caenorhabditis elegans uses gap junctions to provide direct cell-to-cell contact. The nematode gap junctions are formed by innexins (invertebrate analogs of the connexins); a family of proteins that surprisingly share no primary sequence homology, but do share structural and functional similarity with connexins. The model organism C. elegans contains 25 innexin genes and innexins are found in virtually all cell types and tissues. Additionally, many innexins have dynamic expression patterns during development, and several innexins are essential genes in the nematode. C. elegans is a popular invertebrate model due to several features including a simple anatomy, a complete cell lineage, sequenced genome and an array of genetic resources. Thus, the worm has potential to offer valuable insights into the various functions of gap junction mediated intercellular communication.
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Affiliation(s)
- Karina T. Simonsen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British ColumbiaVancouver, BC, Canada
| | - Donald G. Moerman
- Department of Zoology and Michael Smith Laboratories, University of British ColumbiaVancouver, BC, Canada
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British ColumbiaVancouver, BC, Canada
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Xiong XX, Gu LJ, Shen J, Kang XH, Zheng YY, Yue SB, Zhu SM. Probenecid protects against transient focal cerebral ischemic injury by inhibiting HMGB1 release and attenuating AQP4 expression in mice. Neurochem Res 2013; 39:216-24. [PMID: 24317635 DOI: 10.1007/s11064-013-1212-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/31/2013] [Accepted: 11/25/2013] [Indexed: 12/11/2022]
Abstract
Stroke results in inflammation, brain edema, and neuronal death. However, effective neuroprotectants are not available. Recent studies have shown that high mobility group box-1 (HMGB1), a proinflammatory cytokine, contributes to ischemic brain injury. Aquaporin 4 (AQP4), a water channel protein, is considered to play a pivotal role in ischemia-induced brain edema. More recently, studies have shown that pannexin 1 channels are involved in cerebral ischemic injury and the cellular inflammatory response. Here, we examined whether the pannexin 1 channel inhibitor probenecid could reduce focal ischemic brain injury by inhibiting cerebral inflammation and edema. Transient focal ischemia was induced in C57BL/6J mice by middle cerebral artery occlusion (MCAO) for 1 h. Infarct volume, neurological score and cerebral water content were evaluated 48 h after MCAO. Immunostaining, western blot analysis and ELISA were used to assess the effects of probenecid on the cellular inflammatory response, HMGB1 release and AQP4 expression. Administration of probenecid reduced infarct size, decreased cerebral water content, inhibited neuronal death, and reduced inflammation in the brain 48 h after stroke. In addition, HMGB1 release from neurons was significantly diminished and serum HMGB1 levels were substantially reduced following probenecid treatment. Moreover, AQP4 protein expression was downregulated in the cortical penumbra following post-stroke treatment with probenecid. These results suggest that probenecid, a powerful pannexin 1 channel inhibitor, protects against ischemic brain injury by inhibiting cerebral inflammation and edema.
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Affiliation(s)
- Xiao-Xing Xiong
- Department of Anesthesia, the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
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Liu P, Chen B, Altun ZF, Gross MJ, Shan A, Schuman B, Hall DH, Wang ZW. Six innexins contribute to electrical coupling of C. elegans body-wall muscle. PLoS One 2013; 8:e76877. [PMID: 24130800 PMCID: PMC3793928 DOI: 10.1371/journal.pone.0076877] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 08/29/2013] [Indexed: 11/23/2022] Open
Abstract
C. elegans body-wall muscle cells are electrically coupled through gap junctions. Previous studies suggest that UNC-9 is an important, but not the only, innexin mediating the electrical coupling. Here we analyzed junctional current (Ij) for mutants of additional innexins to identify the remaining innexin(s) important to the coupling. The results suggest that a total of six innexins contribute to the coupling, including UNC-9, INX-1, INX-10, INX-11, INX-16, and INX-18. The Ij deficiency in each mutant was rescued completely by expressing the corresponding wild-type innexin specifically in muscle, suggesting that the innexins function cell-autonomously. Comparisons of Ij between various single, double, and triple mutants suggest that the six innexins probably form two distinct populations of gap junctions with one population consisting of UNC-9 and INX-18 and the other consisting of the remaining four innexins. Consistent with their roles in muscle electrical coupling, five of the six innexins showed punctate localization at muscle intercellular junctions when expressed as GFP- or epitope-tagged proteins, and muscle expression was detected for four of them when assessed by expressing GFP under the control of innexin promoters. The results may serve as a solid foundation for further explorations of structural and functional properties of gap junctions in C. elegans body-wall muscle.
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Affiliation(s)
- Ping Liu
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Bojun Chen
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Zeynep F. Altun
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Maegan J. Gross
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Alan Shan
- Undergraduate Summer Research Internship Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Benjamin Schuman
- Undergraduate Summer Research Internship Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - David H. Hall
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- * E-mail:
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Coburn C, Allman E, Mahanti P, Benedetto A, Cabreiro F, Pincus Z, Matthijssens F, Araiz C, Mandel A, Vlachos M, Edwards SA, Fischer G, Davidson A, Pryor RE, Stevens A, Slack FJ, Tavernarakis N, Braeckman BP, Schroeder FC, Nehrke K, Gems D. Anthranilate fluorescence marks a calcium-propagated necrotic wave that promotes organismal death in C. elegans. PLoS Biol 2013; 11:e1001613. [PMID: 23935448 PMCID: PMC3720247 DOI: 10.1371/journal.pbio.1001613] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 06/13/2013] [Indexed: 12/29/2022] Open
Abstract
Death of the nematode Caenorhabditis elegans involves a conserved necrotic cell death cascade which generates endogenous blue anthranilate fluorescence, allowing death to be visualized. For cells the passage from life to death can involve a regulated, programmed transition. In contrast to cell death, the mechanisms of systemic collapse underlying organismal death remain poorly understood. Here we present evidence of a cascade of cell death involving the calpain-cathepsin necrosis pathway that can drive organismal death in Caenorhabditis elegans. We report that organismal death is accompanied by a burst of intense blue fluorescence, generated within intestinal cells by the necrotic cell death pathway. Such death fluorescence marks an anterior to posterior wave of intestinal cell death that is accompanied by cytosolic acidosis. This wave is propagated via the innexin INX-16, likely by calcium influx. Notably, inhibition of systemic necrosis can delay stress-induced death. We also identify the source of the blue fluorescence, initially present in intestinal lysosome-related organelles (gut granules), as anthranilic acid glucosyl esters—not, as previously surmised, the damage product lipofuscin. Anthranilic acid is derived from tryptophan by action of the kynurenine pathway. These findings reveal a central mechanism of organismal death in C. elegans that is related to necrotic propagation in mammals—e.g., in excitotoxicity and ischemia-induced neurodegeneration. Endogenous anthranilate fluorescence renders visible the spatio-temporal dynamics of C. elegans organismal death. In the nematode Caenorhabditis elegans, intestinal lysosome-related organelles (or “gut granules”) contain a bright blue fluorescent substance of unknown identity. This has similar spectral properties to lipofuscin, a product of oxidative damage known to accumulate with age in postmitotic mammalian cells. Blue fluorescence seems to increase in aging worm populations, and lipofuscin has been proposed to be the source. To analyze this further, we measure fluorescence levels after exposure to oxidative stress and during aging in individually tracked worms. Surprisingly, neither of these conditions increases fluorescence levels; instead blue fluorescence increases in a striking and rapid burst at death. Such death fluorescence (DF) also appears in young worms when killed, irrespective of age or cause of death. We chemically identify DF as anthranilic acid glucosyl esters derived from tryptophan, and not lipofuscin. In addition, we show that DF generation in the intestine is dependent upon the necrotic cell death cascade, previously characterized as a driver of neurodegeneration. We find that necrosis spreads in a rapid wave along the intestine by calcium influx via innexin ion channels, accompanied by cytosolic acidosis. Inhibition of necrosis pathway components can delay stress-induced death, supporting its role as a driver of organismal death. This necrotic cascade provides a model system to study neurodegeneration and organismal death.
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Affiliation(s)
- Cassandra Coburn
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Erik Allman
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Parag Mahanti
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Alexandre Benedetto
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Filipe Cabreiro
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Zachary Pincus
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | | | - Caroline Araiz
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Abraham Mandel
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Manolis Vlachos
- Institute of Molecular Biology and Biotechnology, University of Crete, Heraklion, Crete, Greece
| | - Sally-Anne Edwards
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Grahame Fischer
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Alexander Davidson
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Rosina E. Pryor
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Ailsa Stevens
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Frank J. Slack
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, University of Crete, Heraklion, Crete, Greece
| | | | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Keith Nehrke
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - David Gems
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- * E-mail:
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Zhao X, Xu F, Tang L, Du W, Feng X, Liu BF. Microfluidic chip-based C. elegans microinjection system for investigating cell-cell communication in vivo. Biosens Bioelectron 2013; 50:28-34. [PMID: 23831644 DOI: 10.1016/j.bios.2013.06.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 06/09/2013] [Accepted: 06/10/2013] [Indexed: 11/30/2022]
Abstract
The propagation of intercellular calcium wave (ICW) is essential for coordinating cellular activities in multicellular organisms. However, the limitations of existing analytical methods hamper the studies of this biological process in live animals. In this paper, we demonstrated for the first time a novel microfluidic system with an open chamber for on-chip microinjection of C. elegans and investigation of ICW propagations in vivo. Worms were long-term immobilized on the side wall of the open chamber by suction. Using an external micro-manipulator, localized chemical stimulation was delivered to single intestinal cells of the immobilized worms by microinjection. The calcium dynamics in the intestinal cells expressing Ca(2+) indicator YC2.12 was simultaneously monitored by fluorescence imaging. As a result, thapsigargin injection induced ICW was observed in the intestinal cells of C. elegans. Further analysis of the ICW propagation was realized in the presence of heparin (an inhibitor for IP3 receptor), which allowed us to investigate the mechanism underlying intercellular calcium signaling. We expect this novel microfluidic platform to be a useful tool for studying cell-cell communication in multicellular organisms in vivo.
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Affiliation(s)
- Xingfu Zhao
- Britton Chance Center for Biomedical Photonics at Wuhan National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
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Abstract
Pacemaker cells are specialized cell types that drive biological rhythms like the heartbeat and intestinal peristalsis. What determines whether a cell functions as a pacemaker? Studies in Caenorhabditis elegans suggest that pacemaking activity may be controlled in part by microRNAs.
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Affiliation(s)
- Kevin Strange
- Boylan Center for Cellular and Molecular Physiology, and Davis Center for Regenerative Biology and Medicine, Mount Desert Island Biological Laboratory, PO Box 35, Old Bar Harbor Road, Salisbury Cove, ME 04672, USA.
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Diezmos EF, Sandow SL, Markus I, Shevy Perera D, Lubowski DZ, King DW, Bertrand PP, Liu L. Expression and localization of pannexin-1 hemichannels in human colon in health and disease. Neurogastroenterol Motil 2013; 25:e395-405. [PMID: 23594276 DOI: 10.1111/nmo.12130] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/16/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND Pannexin-1 (Panx1) proteins can function as channels for adenosine triphosphate (ATP) release, but there have been limited studies investigating their potential role in the human intestine. The aim of this study was to characterize Panx1 expression and distribution in the human colon and its potential involvement in inflammatory bowel diseases (IBD). METHODS Human colon segments were dissected into mucosa and muscularis layers, and evaluated for Panx1 expression by real-time PCR and Western blotting. Immunohistochemistry was conducted to localize the cellular distribution of Panx1 in intact tissues. KEY RESULTS In the colonic muscularis of ulcerative colitis (UC), Panx1 mRNA expression showed a 3.5-fold reduction compared with control (P = 0.0015), but no change was seen in UC mucosa. In contrast, down-regulation of Panx1 mRNA was observed in both muscularis and mucosa of Crohn's disease (CD), showing a 2.7- and 1.8-fold reduction, respectively (P < 0.05). There was reduced Panx1 protein expression in CD muscularis, but no change in CD mucosa, UC muscularis, or UC mucosa. Pannexin-1 immunoreactivity was mainly localized to enteric ganglia, blood vessel endothelium, erythrocytes, epithelial cells, and goblet cells. Inflammatory bowel disease samples showed a similar overall pattern of Panx1 staining, but in UC myenteric ganglia, there was a significant reduction in Panx1 immunoreactivity. Significant Panx1 positive leukocyte infiltrations were seen at the sites of inflammation. CONCLUSIONS & INFERENCES The presence of Panx1 in the colon and changes to its distribution in disease suggests that Panx1 channels may play an important role in mediating gut function and in IBD pathophysiology.
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Affiliation(s)
- E F Diezmos
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
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Wang H, Girskis K, Janssen T, Chan JP, Dasgupta K, Knowles JA, Schoofs L, Sieburth D. Neuropeptide secreted from a pacemaker activates neurons to control a rhythmic behavior. Curr Biol 2013; 23:746-54. [PMID: 23583549 DOI: 10.1016/j.cub.2013.03.049] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 03/18/2013] [Accepted: 03/20/2013] [Indexed: 10/27/2022]
Abstract
BACKGROUND Rhythmic behaviors are driven by endogenous biological clocks in pacemakers, which must reliably transmit timing information to target tissues that execute rhythmic outputs. During the defecation motor program in C. elegans, calcium oscillations in the pacemaker (intestine), which occur about every 50 s, trigger rhythmic enteric muscle contractions through downstream GABAergic neurons that innervate enteric muscles. However, the identity of the timing signal released by the pacemaker and the mechanism underlying the delivery of timing information to the GABAergic neurons are unknown. RESULTS Here, we show that a neuropeptide-like protein (NLP-40) released by the pacemaker triggers a single rapid calcium transient in the GABAergic neurons during each defecation cycle. We find that mutants lacking nlp-40 have normal pacemaker function, but lack enteric muscle contractions. NLP-40 undergoes calcium-dependent release that is mediated by the calcium sensor, SNT-2/synaptotagmin. We identify AEX-2, the G-protein-coupled receptor on the GABAergic neurons, as the receptor for NLP-40. Functional calcium imaging reveals that NLP-40 and AEX-2/GPCR are both necessary for rhythmic activation of these neurons. Furthermore, acute application of synthetic NLP-40-derived peptide depolarizes the GABAergic neurons in vivo. CONCLUSIONS Our results show that NLP-40 carries the timing information from the pacemaker via calcium-dependent release and delivers it to the GABAergic neurons by instructing their activation. Thus, we propose that rhythmic release of neuropeptides can deliver temporal information from pacemakers to downstream neurons to execute rhythmic behaviors.
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Affiliation(s)
- Han Wang
- Graduate Program in Genetic, Molecular and Cellular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
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Kemp BJ, Allman E, Immerman L, Mohnen M, Peters MA, Nehrke K, Abbott AL. miR-786 regulation of a fatty-acid elongase contributes to rhythmic calcium-wave initiation in C. elegans. Curr Biol 2012; 22:2213-20. [PMID: 23141108 DOI: 10.1016/j.cub.2012.09.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/30/2012] [Accepted: 09/26/2012] [Indexed: 01/09/2023]
Abstract
BACKGROUND Rhythmic behaviors are ubiquitous phenomena in animals. In C. elegans, defecation is an ultradian rhythmic behavior: every ∼50 s a calcium wave initiating in the posterior intestinal cells triggers the defecation motor program that comprises three sequential muscle contractions. Oscillatory calcium signaling is central to the periodicity of defecation. The posteriormost intestinal cells function as the pacemaker for this rhythmic behavior, although it is unclear how the supremacy of these cells for calcium-wave initiation is controlled. RESULTS We describe how the loss of the mir-240/786 microRNA cluster, which results in arrhythmic defecation, causes ectopic intestinal calcium-wave initiation. mir-240/786 expression in the intestine is restricted to the posterior cells that function as the defecation pacemaker. Genetic data indicate that mir-240/786 functions upstream of the inositol 1,4,5-trisphosphate (IP(3)) receptor. Through rescue analysis, it was determined that miR-786 functions to regulate defecation. Furthermore, we identified elo-2, a fatty-acid elongase with a known role in defecation cycling, as a direct target for miR-786. We propose that the regulation of palmitate levels through repression of elo-2 activity is the likely mechanistic link to defecation. CONCLUSIONS Together, these data indicate that miR-786 confers pacemaker status on posterior intestinal cells for the control of calcium-wave initiation through the regulation of elo-2 and, subsequently, palmitate levels. We propose that a difference in fatty-acid composition in the posterior intestinal cells may alter the activities of membrane proteins, such as IP(3)-receptor or TRPM channels, that control pacemaker activity in the C. elegans intestine.
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Affiliation(s)
- Benedict J Kemp
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
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Baylis HA, Vázquez-Manrique RP. Genetic analysis of IP3 and calcium signalling pathways in C. elegans. Biochim Biophys Acta Gen Subj 2011; 1820:1253-68. [PMID: 22146231 DOI: 10.1016/j.bbagen.2011.11.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/15/2011] [Accepted: 11/16/2011] [Indexed: 01/02/2023]
Abstract
BACKGROUND The nematode, Caenorhabditis elegans is an established model system that is particularly well suited to genetic analysis. C. elegans is easily manipulated and we have an in depth knowledge of many aspects of its biology. Thus, it is an attractive system in which to pursue integrated studies of signalling pathways. C. elegans has a complement of calcium signalling molecules similar to that of other animals. SCOPE OF REVIEW We focus on IP3 signalling. We describe how forward and reverse genetic approaches, including RNAi, have resulted in a tool kit which enables the analysis of IP3/Ca2+ signalling pathways. The importance of cell and tissue specific manipulation of signalling pathways and the use of epistasis analysis are highlighted. We discuss how these tools have increased our understanding of IP3 signalling in specific developmental, physiological and behavioural roles. Approaches to imaging calcium signals in C. elegans are considered. MAJOR CONCLUSIONS A wide selection of tools is available for the analysis of IP3/Ca2+ signalling in C. elegans. This has resulted in detailed descriptions of the function of IP3/Ca2+ signalling in the animal's biology. Nevertheless many questions about how IP3 signalling regulates specific processes remain. GENERAL SIGNIFICANCE Many of the approaches described may be applied to other calcium signalling systems. C. elegans offers the opportunity to dissect pathways, perform integrated studies and to test the importance of the properties of calcium signalling molecules to whole animal function, thus illuminating the function of calcium signalling in animals. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signalling.
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Affiliation(s)
- Howard A Baylis
- Department of Zoology, University of Cambridge, Cambridge, UK.
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Kobayashi Y, Kimura KD, Katsura I. Ultradian rhythm in the intestine of Caenorhabditis elegans is controlled by the C-terminal region of the FLR-1 ion channel and the hydrophobic domain of the FLR-4 protein kinase. Genes Cells 2011; 16:565-75. [PMID: 21518154 DOI: 10.1111/j.1365-2443.2011.01508.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Defecation behavior in Caenorhabditis elegans is driven by an endogenous ultradian clock in the intestine. Its periods are positively regulated by FLR-1, an ion channel of the epithelial sodium channel/degenerin superfamily, and FLR-4, a protein kinase with a hydrophobic domain at the carboxyl terminus. FLR-1 has many putative phosphorylation sites in the C-terminal intracellular region. This structure implies that the periods may be regulated by the phosphorylation of FLR-1 by FLR-4, but it remains to be clarified. Here, we show that a truncated FLR-1 lacking the C-terminal intracellular region resulted in longer periods, suggesting that this region is involved in the negative regulation of defecation cycle periods. Contrary to our expectation, FLR-4 was still necessary for the function of the truncated FLR-1. Furthermore, FLR-4 containing a kinase-dead mutation or lacking the whole kinase domain was sufficient for normal defecation cycle periods. FLR-4 was necessary for the stable expression of FLR-1::GFP, and its hydrophobic domain was sufficient also for this function. FLR-1 and FLR-4 are often colocalized in the plasma membrane. These data showed an unexpected role of FLR-4: its hydrophobic domain stabilizes the FLR-1 ion channel, a key regulator of defecation cycle periods in the intestine.
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Affiliation(s)
- Yuri Kobayashi
- Structural Biology Center, National Institute of Genetics, Mishima, Shizuoka-ken, Japan
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Wagner J, Allman E, Taylor A, Ulmschneider K, Kovanda T, Ulmschneider B, Nehrke K, Peters MA. A calcineurin homologous protein is required for sodium-proton exchange events in the C. elegans intestine. Am J Physiol Cell Physiol 2011; 301:C1389-403. [PMID: 21865588 DOI: 10.1152/ajpcell.00139.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Caenorhabditis elegans defecation is a rhythmic behavior, composed of three sequential muscle contractions, with a 50-s periodicity. The motor program is driven by oscillatory calcium signaling in the intestine. Proton fluxes, which require sodium-proton exchangers at the apical and basolateral intestinal membranes, parallel the intestinal calcium flux. These proton shifts are critical for defecation-associated muscle contraction, nutrient uptake, and longevity. How sodium-proton exchangers are activated in time with intestinal calcium oscillation is not known. The posterior body defecation contraction mutant (pbo-1) encodes a calcium-binding protein with homology to calcineurin homologous proteins, which are putative cofactors for mammalian sodium-proton exchangers. Loss of pbo-1 function results in a weakened defecation muscle contraction and a caloric restriction phenotype. Both of these phenotypes also arise from dysfunctions in pH regulation due to mutations in intestinal sodium-proton exchangers. Dynamic, in vivo imaging of intestinal proton flux in pbo-1 mutants using genetically encoded pH biosensors demonstrates that proton movements associated with these sodium-proton exchangers are significantly reduced. The basolateral acidification that signals the first defecation motor contraction is scant in the mutant compared with a normal animal. Luminal and cytoplasmic pH shifts are much reduced in the absence of PBO-1 compared with control animals. We conclude that pbo-1 is required for normal sodium-proton exchanger activity and may couple calcium and proton signaling events.
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Affiliation(s)
- Jamie Wagner
- Dept. of Biology, Oberlin College, Oberlin, OH 44074, USA
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Panchin YV. Intercellular channels in animals. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s0006350911030225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Liu Y, LeBeouf B, Guo X, Correa PA, Gualberto DG, Lints R, Garcia LR. A cholinergic-regulated circuit coordinates the maintenance and bi-stable states of a sensory-motor behavior during Caenorhabditis elegans male copulation. PLoS Genet 2011; 7:e1001326. [PMID: 21423722 PMCID: PMC3053324 DOI: 10.1371/journal.pgen.1001326] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 02/04/2011] [Indexed: 11/18/2022] Open
Abstract
Penetration of a male copulatory organ into a suitable mate is a conserved and necessary behavioral step for most terrestrial matings; however, the detailed molecular and cellular mechanisms for this distinct social interaction have not been elucidated in any animal. During mating, the Caenorhabditis elegans male cloaca is maintained over the hermaphrodite's vulva as he attempts to insert his copulatory spicules. Rhythmic spicule thrusts cease when insertion is sensed. Circuit components consisting of sensory/motor neurons and sex muscles for these steps have been previously identified, but it was unclear how their outputs are integrated to generate a coordinated behavior pattern. Here, we show that cholinergic signaling between the cloacal sensory/motor neurons and the posterior sex muscles sustains genital contact between the sexes. Simultaneously, via gap junctions, signaling from these muscles is transmitted to the spicule muscles, thus coupling repeated spicule thrusts with vulval contact. To transit from rhythmic to sustained muscle contraction during penetration, the SPC sensory-motor neurons integrate the signal of spicule's position in the vulva with inputs from the hook and cloacal sensilla. The UNC-103 K(+) channel maintains a high excitability threshold in the circuit, so that sustained spicule muscle contraction is not stimulated by fewer inputs. We demonstrate that coordination of sensory inputs and motor outputs used to initiate, maintain, self-monitor, and complete an innate behavior is accomplished via the coupling of a few circuit components.
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Affiliation(s)
- Yishi Liu
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Brigitte LeBeouf
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- Howard Hughes Medical Institute, Texas A&M University, College Station, Texas, United States of America
| | - Xiaoyan Guo
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Paola A. Correa
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Daisy G. Gualberto
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- Howard Hughes Medical Institute, Texas A&M University, College Station, Texas, United States of America
| | - Robyn Lints
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - L. Rene Garcia
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- Howard Hughes Medical Institute, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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Govorunova EG, Moussaif M, Kullyev A, Nguyen KCQ, McDonald TV, Hall DH, Sze JY. A homolog of FHM2 is involved in modulation of excitatory neurotransmission by serotonin in C. elegans. PLoS One 2010; 5:e10368. [PMID: 20442779 PMCID: PMC2860991 DOI: 10.1371/journal.pone.0010368] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2009] [Accepted: 03/30/2010] [Indexed: 01/13/2023] Open
Abstract
The C. elegans eat-6 gene encodes a Na(+), K(+)-ATPase alpha subunit and is a homolog of the familial hemiplegic migraine candidate gene FHM2. Migraine is the most common neurological disorder linked to serotonergic dysfunction. We sought to study the pathophysiological mechanisms of migraine and their relation to serotonin (5-HT) signaling using C. elegans as a genetic model. In C. elegans, exogenous 5-HT inhibits paralysis induced by the acetylcholinesterase inhibitor aldicarb. We found that the eat-6(ad467) mutation or RNAi of eat-6 increases aldicarb sensitivity and causes complete resistance to 5-HT treatment, indicating that EAT-6 is a component of the pathway that couples 5-HT signaling and ACh neurotransmission. While a postsynaptic role of EAT-6 at the bodywall NMJs has been well established, we found that EAT-6 may in addition regulate presynaptic ACh neurotransmission. We show that eat-6 is expressed in ventral cord ACh motor neurons, and that cell-specific RNAi of eat-6 in the ACh neurons leads to hypersensitivity to aldicarb. Electron microscopy showed an increased number of synaptic vesicles in the ACh neurons in the eat-6(ad467) mutant. Genetic analyses suggest that EAT-6 interacts with EGL-30 Galphaq, EGL-8 phospholipase C and SLO-1 BK channel signaling to modulate ACh neurotransmission and that either reduced or excessive EAT-6 function may lead to increased ACh neurotransmission. Study of the interaction between eat-6 and 5-HT receptors revealed both stimulatory and inhibitory 5-HT inputs to the NMJs. We show that the inhibitory and stimulatory 5-HT signals arise from distinct 5-HT neurons. The role of eat-6 in modulation of excitatory neurotransmission by 5-HT may provide a genetic explanation for the therapeutic effects of the drugs targeting 5-HT receptors in the treatment of migraine patients.
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Affiliation(s)
- Elena G. Govorunova
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Mustapha Moussaif
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Andrey Kullyev
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Ken C. Q. Nguyen
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Thomas V. McDonald
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - David H. Hall
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Ji Y. Sze
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America
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Gap junctions and memory: An investigation using a single trial discrimination avoidance task for the neonate chick. Neurobiol Learn Mem 2010; 93:189-95. [DOI: 10.1016/j.nlm.2009.09.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Revised: 07/21/2009] [Accepted: 09/22/2009] [Indexed: 11/15/2022]
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Xing J, Strange K. Phosphatidylinositol 4,5-bisphosphate and loss of PLCgamma activity inhibit TRPM channels required for oscillatory Ca2+ signaling. Am J Physiol Cell Physiol 2009; 298:C274-82. [PMID: 19923421 DOI: 10.1152/ajpcell.00394.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Caenorhabditis elegans intestinal epithelium generates rhythmic inositol 1,4,5-trisphosphate (IP(3))-dependent Ca(2+) oscillations that control muscle contractions required for defecation. Two highly Ca(2+)-selective transient receptor potential (TRP) melastatin (TRPM) channels, GON-2 and GTL-1, function with PLCgamma in a common signaling pathway that regulates IP(3)-dependent intracellular Ca(2+) release. A second PLC, PLCbeta, is also required for IP(3)-dependent Ca(2+) oscillations, but functions in an independent signaling mechanism. PLCgamma generates IP(3) that regulates IP(3) receptor activity. We demonstrate here that PLCgamma via hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP(2)) also regulates GON-2/GTL-1 function. Knockdown of PLCgamma but not PLCbeta activity by RNA interference (RNAi) inhibits channel activity approximately 80%. Inhibition is fully reversed by agents that deplete PIP(2) levels. PIP(2) added to the patch pipette has no effect on channel activity in PLCgamma RNAi cells. However, in control cells, 10 microM PIP(2) inhibits whole cell current approximately 80%. Channel inhibition by phospholipids is selective for PIP(2) with an IC(50) value of 2.6 microM. Elevated PIP(2) levels have no effect on channel voltage and Ca(2+) sensitivity and likely inhibit by reducing channel open probability, single-channel conductance, and/or trafficking. We conclude that hydrolysis of PIP(2) by PLCgamma functions in the activation of both the IP(3) receptor and GON-2/GTL-1 channels. GON-2/GTL-1 functions as the major intestinal cell Ca(2+) influx pathway. Calcium influx through the channel feedback regulates its activity and likely functions to modulate IP(3) receptor function. PIP(2)-dependent regulation of GON-2/GTL-1 may provide a mechanism to coordinate plasma membrane Ca(2+) influx with PLCgamma and IP(3) receptor activity as well as intracellular Ca(2+) store depletion.
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Affiliation(s)
- Juan Xing
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Allman E, Johnson D, Nehrke K. Loss of the apical V-ATPase a-subunit VHA-6 prevents acidification of the intestinal lumen during a rhythmic behavior in C. elegans. Am J Physiol Cell Physiol 2009; 297:C1071-81. [PMID: 19741196 PMCID: PMC2777397 DOI: 10.1152/ajpcell.00284.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 09/09/2009] [Indexed: 11/22/2022]
Abstract
In Caenorhabditis elegans, oscillations of intestinal pH contribute to the rhythmic defecation behavior, but the acid-base transport mechanisms that facilitate proton movement are not well understood. Here, we demonstrate that VHA-6, an intestine-specific a-subunit of the H(+)-K(+)-ATPase complex (V-ATPase), resides in the apical membrane of the intestinal epithelial cells and is required for luminal acidification. Disruption of the vha-6 gene led to early developmental arrest; the arrest phenotype could be complemented by expression of a fluorescently labeled vha-6 transgene. To study the contribution of vha-6 to pH homeostasis in larval worms, we used a partial reduction of function through postembryonic single-generation RNA interference. We demonstrate that the inability to fully acidify the intestinal lumen coincides with a defect in pH recovery of the intestinal epithelial cells, suggesting that VHA-6 is essential for proton pumping following defecation. Moreover, intestinal dipeptide accumulation and fat storage are compromised by the loss of VHA-6, suggesting that luminal acidification promotes nutrient uptake in worms, as well as in mammals. Since acidified intracellular vesicles and autofluorescent storage granules are indistinguishable between the vha-6 mutant and controls, it is likely that the nutrient-restricted phenotype is due to a loss of plasma membrane V-ATPase activity specifically. These data establish a simple genetic model for proton pump-driven acidification. Since defecation occurs at 45-s intervals in worms, this model represents an opportunity to study acute regulation of V-ATPase activity on a short time scale and may be useful in the study of alternative treatments for acid-peptic disorders.
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Affiliation(s)
- Erik Allman
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York 14642, USA
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Fu Y, Ren M, Feng H, Chen L, Altun ZF, Rubin CS. Neuronal and intestinal protein kinase d isoforms mediate Na+ (salt taste)-induced learning. Sci Signal 2009; 2:ra42. [PMID: 19671928 DOI: 10.1126/scisignal.2000224] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ubiquitously expressed protein kinase D (PKD) isoforms are poised to disseminate signals carried by diacylglycerol (DAG). However, the in vivo regulation and functions of PKDs are poorly understood. We show that the Caenorhabditis elegans gene, dkf-2, encodes not just DKF-2A, but also a second previously unknown isoform, DKF-2B. Whereas DKF-2A is present mainly in intestine, we show that DKF-2B is found in neurons. Characterization of dkf-2 null mutants and transgenic animals expressing DKF-2B, DKF-2A, or both isoforms revealed that PKDs couple DAG signals to regulation of sodium ion (Na+)-induced learning. EGL-8 (a phospholipase Cbeta4 homolog) and TPA-1 (a protein kinase Cdelta homolog) are upstream regulators of DKF-2 isoforms in vivo. Thus, pathways containing EGL-8-TPA-1-DKF-2 enable learning and behavioral plasticity by receiving, transmitting, and cooperatively integrating environmental signals targeted to both neurons and intestine.
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Affiliation(s)
- Ya Fu
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Abstract
The innexin family of gap junction proteins has 25 members in Caenorhabditis elegans. Here, we describe the first high-resolution expression map of all members through analysis of live worms transformed with green fluorescent protein under the control of entire promoter regions. Our analyses show that innexins have dynamic expression patterns throughout development and are found in virtually all cell types and tissues. Complex tissues, such as the pharynx, intestine, gonad, as well as scaffolding tissues and guidepost cells express a variety of innexins in overlapping or complementary patterns, suggesting they may form heteromeric and heterotypic channels. Innexin expression occurs in several types of cells that are not known to form gap junctions as well as in a pair of migrating cells, suggesting they may have hemichannel function. Therefore, innexins likely play roles in almost all body functions, including embryonic development, cell fate determination, oogenesis, egg laying, pharyngeal pumping, excretion, and locomotion.
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Affiliation(s)
- Zeynep F Altun
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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Abstract
In a genetic screen for active zone defective mutants in Caenorhabditis elegans, we isolated a loss-of-function allele of unc-7, a gene encoding an innexin/pannexin family gap junction protein. Innexin UNC-7 regulates the size and distribution of active zones at C. elegans neuromuscular junctions. Loss-of-function mutations in another innexin, UNC-9, cause similar active zone defects as unc-7 mutants. In addition to presumptive gap junction localizations, both UNC-7 and UNC-9 are also localized perisynaptically throughout development and required in presynaptic neurons to regulate active zone differentiation. Our mosaic analyses, electron microscopy, as well as expression studies suggest a novel and likely nonjunctional role of specific innexins in active zone differentiation in addition to gap junction formations.
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Wang XH, Streeter M, Liu YP, Zhao HB. Identification and characterization of pannexin expression in the mammalian cochlea. J Comp Neurol 2009; 512:336-46. [PMID: 19009624 PMCID: PMC2630187 DOI: 10.1002/cne.21898] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The gap junction in vertebrates is encoded by the connexin gene family. Recently, a new gene family termed pannexin (Panx) has been identified in vertebrates and found to encode gap junctional proteins as well. To date, three pannexin isoforms (Panx1, 2, and 3) have been cloned from mouse and human genomes. In this study, expression of pannexins in the mouse and rat cochlea was investigated. Polymerase chain reaction and Western blot analysis showed that all three pannexin isoforms were expressed in the cochlea. Immunofluorescent staining showed that Panx1 expression was extensive. In the organ of Corti, Panx1 labeling was found in supporting cells, including pillar cells, Hensen cells, Claudius cells, and Boettcher cells. Both surface plaque-like punctate labeling and diffuse-cytoplasmic labeling were visible. However, the labeling was weak and rare in Deiters cells. No labeling was found in the hair cells. Intense labeling for Panx1 was also observed in the interdental cells in the spiral limbus, the inner and outer sulcus cells, and the type II fibrocytes in the spiral prominence and central region in the cochlear lateral wall. In addition, Panx1 labeling was detectable in Reissner's membrane and strial blood vessel cells. Panx2 labeling was restricted to the basal cells in the stria vascularis and was also detectable in the spiral ganglion neurons. However, no overlapping labeling for Panx1 and Panx2 was observed. Finally, Panx3 labeling was exclusively observed in the cochlear bone. Thus, Panx1, 2, and 3 are abundantly expressed in the mammalian cochlea and demonstrate distinct cellular distributions. Like connexins, they may play an important role in hearing.
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Affiliation(s)
- Xiao-Hui Wang
- Department of Surgery-Otolaryngology, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA
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Mahoney TR, Luo S, Round EK, Brauner M, Gottschalk A, Thomas JH, Nonet ML. Intestinal signaling to GABAergic neurons regulates a rhythmic behavior in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2008; 105:16350-5. [PMID: 18852466 PMCID: PMC2570992 DOI: 10.1073/pnas.0803617105] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Indexed: 11/18/2022] Open
Abstract
The Caenorhabditis elegans defecation motor program (DMP) is a highly coordinated rhythmic behavior that requires two GABAergic neurons that synapse onto the enteric muscles. One class of DMP mutants, called anterior body wall muscle contraction and expulsion defective (aex) mutants, exhibits similar defects to those caused by the loss of these two neurons. Here, we demonstrate that aex-2 encodes a G-protein-coupled receptor (GPCR) and aex-4 encodes an exocytic SNAP25 homologue. We found that aex-2 functions in the nervous system and activates a G(s)alpha signaling pathway to regulate defecation. aex-4, on the other hand, functions in the intestinal epithelial cells. Furthermore, we show that aex-5, which encodes a pro-protein convertase, functions in the intestine to regulate the DMP and that its secretion from the intestine is impaired in aex-4 mutants. Activation of the G(s)alpha GPCR pathway in GABAergic neurons can suppress the defecation defect of the intestinal mutants aex-4 and aex-5. Lastly, we demonstrate that activation of GABAergic neurons using the light-gated cation channel channelrhodopsin-2 is sufficient to suppress the behavioral defects of aex-2, aex-4, and aex-5. These results genetically place intestinal genes aex-4 and aex-5 upstream of GABAergic GPCR signaling. We propose a model whereby the intestinal genes aex-4 and aex-5 control the DMP by regulating the secretion of a signal, which activates the neuronal receptor aex-2.
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Affiliation(s)
- Timothy R. Mahoney
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Shuo Luo
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Elaine K. Round
- Department of Genome Sciences, University of Washington, Seattle, WA 98195; and
| | - Martin Brauner
- Institute for Biochemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe-University Frankfurt, D-60439 Frankfurt, Germany
| | - Alexander Gottschalk
- Institute for Biochemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe-University Frankfurt, D-60439 Frankfurt, Germany
| | - James H. Thomas
- Department of Genome Sciences, University of Washington, Seattle, WA 98195; and
| | - Michael L. Nonet
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110
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