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Boštjančić LL, Francesconi C, Rutz C, Hoffbeck L, Poidevin L, Kress A, Jussila J, Makkonen J, Feldmeyer B, Bálint M, Schwenk K, Lecompte O, Theissinger K. Host-pathogen coevolution drives innate immune response to Aphanomyces astaci infection in freshwater crayfish: transcriptomic evidence. BMC Genomics 2022; 23:600. [PMID: 35989333 PMCID: PMC9394032 DOI: 10.1186/s12864-022-08571-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 04/20/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND For over a century, scientists have studied host-pathogen interactions between the crayfish plague disease agent Aphanomyces astaci and freshwater crayfish. It has been hypothesised that North American crayfish hosts are disease-resistant due to the long-lasting coevolution with the pathogen. Similarly, the increasing number of latent infections reported in the historically sensitive European crayfish hosts seems to indicate that similar coevolutionary processes are occurring between European crayfish and A. astaci. Our current understanding of these host-pathogen interactions is largely focused on the innate immunity processes in the crayfish haemolymph and cuticle, but the molecular basis of the observed disease-resistance and susceptibility remain unclear. To understand how coevolution is shaping the host's molecular response to the pathogen, susceptible native European noble crayfish and invasive disease-resistant marbled crayfish were challenged with two A. astaci strains of different origin: a haplogroup A strain (introduced to Europe at least 50 years ago, low virulence) and a haplogroup B strain (signal crayfish in lake Tahoe, USA, high virulence). Here, we compare the gene expression profiles of the hepatopancreas, an integrated organ of crayfish immunity and metabolism. RESULTS We characterised several novel innate immune-related gene groups in both crayfish species. Across all challenge groups, we detected 412 differentially expressed genes (DEGs) in the noble crayfish, and 257 DEGs in the marbled crayfish. In the noble crayfish, a clear immune response was detected to the haplogroup B strain, but not to the haplogroup A strain. In contrast, in the marbled crayfish we detected an immune response to the haplogroup A strain, but not to the haplogroup B strain. CONCLUSIONS We highlight the hepatopancreas as an important hub for the synthesis of immune molecules in the response to A. astaci. A clear distinction between the innate immune response in the marbled crayfish and the noble crayfish is the capability of the marbled crayfish to mobilise a higher variety of innate immune response effectors. With this study we outline that the type and strength of the host immune response to the pathogen is strongly influenced by the coevolutionary history of the crayfish with specific A. astaci strains.
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Affiliation(s)
- Ljudevit Luka Boštjančić
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Senckenberg Biodiversity and Climate Research Centre, Georg-Voigt-Str. 14-16, 60325, Frankfurt am Main, Germany
| | - Caterina Francesconi
- Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany.
| | - Christelle Rutz
- Department of Computer Science, ICube, UMR 7357, University of Strasbourg, CNRS, Centre de Recherche en Biomédecine de Strasbourg, Rue Eugène Boeckel 1, 67000, Strasbourg, France
| | - Lucien Hoffbeck
- Department of Computer Science, ICube, UMR 7357, University of Strasbourg, CNRS, Centre de Recherche en Biomédecine de Strasbourg, Rue Eugène Boeckel 1, 67000, Strasbourg, France
| | - Laetitia Poidevin
- Department of Computer Science, ICube, UMR 7357, University of Strasbourg, CNRS, Centre de Recherche en Biomédecine de Strasbourg, Rue Eugène Boeckel 1, 67000, Strasbourg, France
| | - Arnaud Kress
- Department of Computer Science, ICube, UMR 7357, University of Strasbourg, CNRS, Centre de Recherche en Biomédecine de Strasbourg, Rue Eugène Boeckel 1, 67000, Strasbourg, France
| | - Japo Jussila
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, 70210, Kuopio, Finland
| | - Jenny Makkonen
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, 70210, Kuopio, Finland
- Present address: BioSafe - Biological Safety Solutions, Microkatu 1, 70210, Kuopio, Finland
| | - Barbara Feldmeyer
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Senckenberg Biodiversity and Climate Research Centre, Georg-Voigt-Str. 14-16, 60325, Frankfurt am Main, Germany
| | - Miklós Bálint
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Senckenberg Biodiversity and Climate Research Centre, Georg-Voigt-Str. 14-16, 60325, Frankfurt am Main, Germany
| | - Klaus Schwenk
- Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany
| | - Odile Lecompte
- Department of Computer Science, ICube, UMR 7357, University of Strasbourg, CNRS, Centre de Recherche en Biomédecine de Strasbourg, Rue Eugène Boeckel 1, 67000, Strasbourg, France
| | - Kathrin Theissinger
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Senckenberg Biodiversity and Climate Research Centre, Georg-Voigt-Str. 14-16, 60325, Frankfurt am Main, Germany
- Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany
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2
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Neves JH, Rezende-Teixeira P, Palomino NB, Machado-Santelli GM. Molecular and morphological approach to study the innexin gap junctions in Rhynchosciara americana. Open Biol 2021; 11:210224. [PMID: 34753320 PMCID: PMC8580445 DOI: 10.1098/rsob.210224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Gap junctions mediate communication between adjacent cells and are fundamental to the development and homeostasis in multicellular organisms. In invertebrates, gap junctions are formed by transmembrane proteins called innexins. Gap junctions allow the passage of small molecules through an intercellular channel, between a cell and another adjacent cell. The dipteran Rhynchosciara americana has contributed to studying the biology of invertebrates and the study of the interaction and regulation of genes during biological development. Therefore, this paper aimed to study the R. americana innexin-2 by molecular characterization, analysis of the expression profile and cellular localization. The molecular characterization results confirm that the message is from a gap junction protein and analysis of the expression and cellular localization profile shows that innexin-2 can participate in many physiological processes during the development of R. americana.
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Affiliation(s)
- Jorge Henrique Neves
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Paula Rezende-Teixeira
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Natalia Bazan Palomino
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
| | - Glaucia Maria Machado-Santelli
- Institute of Biomedical Sciences, University of São Paulo, Avenida Professor Lineu Prestes, 1524 – sala 307, São Paulo, SP, Brazil
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3
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Heath-Heckman E, Yoo S, Winchell C, Pellegrino M, Angstadt J, Lammardo VB, Bautista D, De-Miguel FF, Weisblat D. Transcriptional profiling of identified neurons in leech. BMC Genomics 2021; 22:215. [PMID: 33765928 PMCID: PMC7992859 DOI: 10.1186/s12864-021-07526-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 03/11/2021] [Indexed: 12/13/2022] Open
Abstract
Background While leeches in the genus Hirudo have long been models for neurobiology, the molecular underpinnings of nervous system structure and function in this group remain largely unknown. To begin to bridge this gap, we performed RNASeq on pools of identified neurons of the central nervous system (CNS): sensory T (touch), P (pressure) and N (nociception) neurons; neurosecretory Retzius cells; and ganglia from which these four cell types had been removed. Results Bioinformatic analyses identified 3565 putative genes whose expression differed significantly among the samples. These genes clustered into 9 groups which could be associated with one or more of the identified cell types. We verified predicted expression patterns through in situ hybridization on whole CNS ganglia, and found that orthologous genes were for the most part similarly expressed in a divergent leech genus, suggesting evolutionarily conserved roles for these genes. Transcriptional profiling allowed us to identify candidate phenotype-defining genes from expanded gene families. Thus, we identified one of eight hyperpolarization-activated cyclic-nucleotide gated (HCN) channels as a candidate for mediating the prominent sag current in P neurons, and found that one of five inositol triphosphate receptors (IP3Rs), representing a sub-family of IP3Rs absent from vertebrate genomes, is expressed with high specificity in T cells. We also identified one of two piezo genes, two of ~ 65 deg/enac genes, and one of at least 16 transient receptor potential (trp) genes as prime candidates for involvement in sensory transduction in the three distinct classes of leech mechanosensory neurons. Conclusions Our study defines distinct transcriptional profiles for four different neuronal types within the leech CNS, in addition to providing a second ganglionic transcriptome for the species. From these data we identified five gene families that may facilitate the sensory capabilities of these neurons, thus laying the basis for future work leveraging the strengths of the leech system to investigate the molecular processes underlying and linking mechanosensation, cell type specification, and behavior. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07526-0.
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Affiliation(s)
- Elizabeth Heath-Heckman
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA. .,Current address: Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.
| | - Shinja Yoo
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Christopher Winchell
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Maurizio Pellegrino
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,Current address: Invitae Corporation, San Francisco, CA, USA
| | - James Angstadt
- Department of Biology, Siena College, Loudonville, New York, NY, USA
| | | | - Diana Bautista
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Francisco F De-Miguel
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - David Weisblat
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
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Christie AE, Hull JJ, Dickinson PS. In silico analyses suggest the cardiac ganglion of the lobster, Homarus americanus, contains a diverse array of putative innexin/innexin-like proteins, including both known and novel members of this protein family. INVERTEBRATE NEUROSCIENCE 2020; 20:5. [PMID: 32115669 DOI: 10.1007/s10158-020-0238-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 01/31/2020] [Indexed: 01/16/2023]
Abstract
Gap junctions are physical channels that connect adjacent cells, permitting the flow of small molecules/ions between the cytoplasms of the coupled units. Innexin/innexin-like proteins are responsible for the formation of invertebrate gap junctions. Within the nervous system, gap junctions often function as electrical synapses, providing a means for coordinating activity among electrically coupled neurons. While some gap junctions allow the bidirectional flow of small molecules/ions between coupled cells, others permit flow in one direction only or preferentially. The complement of innexins present in a gap junction determines its specific properties. Thus, understanding innexin diversity is key for understanding the full potential of electrical coupling in a species/system. The decapod crustacean cardiac ganglion (CG), which controls cardiac muscle contractions, is a simple pattern-generating neural network with extensive electrical coupling among its circuit elements. In the lobster, Homarus americanus, prior work suggested that the adult neuronal innexin complement consists of six innexins (Homam-Inx1-4 and Homam-Inx6-7). Here, using a H. americanus CG-specific transcriptome, we explored innexin complement in this portion of the lobster nervous system. With the exception of Homam-Inx4, all of the previously described innexins appear to be expressed in the H. americanus CG. In addition, transcripts encoding seven novel putative innexins (Homam-Inx8-14) were identified, four (Homam-Inx8-11) having multiple splice variants, e.g., six for Homam-Inx8. Collectively, these data indicate that the innexin complement of the lobster nervous system in general, and the CG specifically, is likely significantly greater than previously reported, suggesting the possibility of expanded gap junction diversity and function in H. americanus.
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Affiliation(s)
- Andrew E Christie
- Békésy Laboratory of Neurobiology, Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, 1993 East-West Road, Honolulu, HI, 96822, USA.
| | - J Joe Hull
- Pest Management and Biocontrol Research Unit, US Arid Land Agricultural Research Center, USDA Agricultural Research Services, Maricopa, AZ, 85138, USA
| | - Patsy S Dickinson
- Department of Biology, Bowdoin College, 6500 College Station, Brunswick, ME, 04011, USA
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5
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Segura OM, Abdulnoor L, Hua VV, Solano MJ, Macagno ER, Baker MW. Purinergic modulation of neuronal gap junction circuits in the CNS of the leech. J Neurosci Res 2020; 98:1232-1249. [PMID: 32096570 DOI: 10.1002/jnr.24599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 01/25/2020] [Accepted: 02/05/2020] [Indexed: 11/08/2022]
Abstract
Gap junctions (GJs) are widely distributed in brains across the animal kingdom. To visualize the GJ- coupled networks of two major mechanosensory neurons in the ganglia of medicinal leeches, we injected these cells with the GJ-permeable tracer Neurobiotin. When diffusion time was limited to only 30 min, tracer coupling was highly variable for both cells, suggesting a possible modulation of GJ permeability. In invertebrates the innexins (homologs of vertebrate pannexins) form the GJs. Because extracellular adenosine triphosphate (ATP) modulates pannexin and leech innexin hemichannel permeability and is released by leech glial cells following injury, we tested the effects of bath application of ATP after the injection of Neurobiotin and observed a significant increase in the number of neurons tracer coupled to the sensory neurons. This effect required the elevation of intracellular Ca2+ and could be produced by bath application of caffeine. Conversely, scavenging endogenous extracellular ATP with the ATPase apyrase decreased the number of coupled cells. ATP also increased electrical conductance and tracer permeability between the bilateral Retzius neurons. This modulatory effect of ATP on GJ coupling was blocked by siRNA knockdown of a P1-like adenosine receptor. Finally, exposure of leech ganglia to extracellular ATP induced a characteristic low frequency (<0.3 Hz) rhythmic bursting activity that was roughly synchronous among multiple neurons, a behavior that was significantly attenuated by the GJ blocker octanol. These findings highlight the mediation by ATP of a robust physiological mechanism for modifying neuronal circuits by rapidly recruiting neurons into active networks and entraining synchronized bursting activity.
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Affiliation(s)
- Oliva Mota Segura
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Lina Abdulnoor
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Vinh-Vincent Hua
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Martha J Solano
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Eduardo R Macagno
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Michael W Baker
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.,Department of Psychology, Mount Saint Vincent University, Halifax, Nova Scotia, Canada
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6
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Mersman BA, Jolly SN, Lin Z, Xu F. Gap Junction Coding Innexin in Lymnaea stagnalis: Sequence Analysis and Characterization in Tissues and the Central Nervous System. Front Synaptic Neurosci 2020; 12:1. [PMID: 32158385 PMCID: PMC7052179 DOI: 10.3389/fnsyn.2020.00001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/09/2020] [Indexed: 11/19/2022] Open
Abstract
Connections between neurons called synapses are the key components underlying all nervous system functions of animals and humans. However, important genetic information on the formation and plasticity of one type, the electrical (gap junction-mediated) synapse, is understudied in many invertebrates. In the present study, we set forth to identify and characterize the gap junction-encoding gene innexin in the central nervous system (CNS) of the mollusk pond snail Lymnaea stagnalis. With PCR, 3′ and 5′ RACE, and BLAST searches, we identified eight innexin genes in the L. stagnalis genome, named Lst Inx1–Lst Inx8. Phylogenetic analysis revealed that the L. stagnalis innexin genes originated from a single copy in the common ancestor of molluskan species by multiple gene duplication events and have been maintained in L. stagnalis since they were generated. The paralogous innexin genes demonstrate distinct expression patterns among tissues. In addition, one paralog, Lst Inx1, exhibits heterogeneity in cells and ganglia, suggesting the occurrence of functional diversification after gene duplication. These results introduce possibilities to study an intriguing potential relationship between innexin paralog expression and cell-specific functional outputs such as heterogenic ability to form channels and exhibit synapse plasticity. The L. stagnalis CNS contains large neurons and functionally defined networks for behaviors; with the introduction of L. stagnalis in the gap junction gene field, we are providing novel opportunities to combine genetic research with direct investigations of functional outcomes at the cellular, synaptic, and behavioral levels.
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Affiliation(s)
- Brittany A Mersman
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States.,Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University, St. Louis, MO, United States
| | - Sonia N Jolly
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States
| | - Zhenguo Lin
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States
| | - Fenglian Xu
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States.,Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University, St. Louis, MO, United States
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7
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Lybrand ZR, Martinez-Acosta VG, Zoran MJ. Coupled sensory interneurons mediate escape neural circuit processing in an aquatic annelid worm, Lumbriculus variegatus. J Comp Neurol 2020; 528:468-480. [PMID: 31502251 DOI: 10.1002/cne.24769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/25/2019] [Accepted: 08/30/2019] [Indexed: 11/08/2022]
Abstract
The interneurons associated with rapid escape circuits are adapted for fast pathway activation and rapid conduction. An essential aspect of fast activation is the processing of sensory information with limited delays. Although aquatic annelid worms have some of the fastest escape responses in nature, the sensory networks that mediate their escape behavior are not well defined. Here, we demonstrate that the escape circuit of the mud worm, Lumbriculus variegatus, is a segmentally arranged network of sensory interneurons electrically coupled to the central medial giant fiber (MGF), the command-like interneuron for head withdrawal. Electrical stimulation of the body wall evoked fast, short-duration spikelets in the MGF, which we suggest are the product of intermediate giant fiber activation coupled to MGF collateral dendrites. Since these contact sites have immunoreactivity with a glutamate receptor antibody, and the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dion abolishes evoked MGF responses, we conclude that the afferent pathway for MGF-mediated escape is glutamatergic. This electrically coupled sensory network may facilitate rapid escape activation by enhancing the amplitude of giant axon depolarization.
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Affiliation(s)
- Zane R Lybrand
- Department of Biology, University of Texas, San Antonio, Texas
| | | | - Mark J Zoran
- Department of Biology, Texas A&M University, College Station, Texas
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8
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Sánchez A, Castro C, Flores DL, Gutiérrez E, Baldi P. Gap Junction Channels of Innexins and Connexins: Relations and Computational Perspectives. Int J Mol Sci 2019; 20:E2476. [PMID: 31109150 PMCID: PMC6566657 DOI: 10.3390/ijms20102476] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/04/2019] [Accepted: 05/14/2019] [Indexed: 12/16/2022] Open
Abstract
Gap junction (GJ) channels in invertebrates have been used to understand cell-to-cell communication in vertebrates. GJs are a common form of intercellular communication channels which connect the cytoplasm of adjacent cells. Dysregulation and structural alteration of the gap junction-mediated communication have been proven to be associated with a myriad of symptoms and tissue-specific pathologies. Animal models relying on the invertebrate nervous system have exposed a relationship between GJs and the formation of electrical synapses during embryogenesis and adulthood. The modulation of GJs as a therapeutic and clinical tool may eventually provide an alternative for treating tissue formation-related diseases and cell propagation. This review concerns the similarities between Hirudo medicinalis innexins and human connexins from nucleotide and protein sequence level perspectives. It also sets forth evidence of computational techniques applied to the study of proteins, sequences, and molecular dynamics. Furthermore, we propose machine learning techniques as a method that could be used to study protein structure, gap junction inhibition, metabolism, and drug development.
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Affiliation(s)
- Alejandro Sánchez
- Facultad de Ciencias, Universidad Autónoma de Baja California, Ensenada, Baja California 22860, Mexico.
| | - Carlos Castro
- Facultad of Ingeniería, Arquitectura y Diseño, Universidad Autónoma de Baja California, Ensenada, Baja California 22860, Mexico.
| | - Dora-Luz Flores
- Facultad of Ingeniería, Arquitectura y Diseño, Universidad Autónoma de Baja California, Ensenada, Baja California 22860, Mexico.
| | - Everardo Gutiérrez
- Facultad de Ciencias, Universidad Autónoma de Baja California, Ensenada, Baja California 22860, Mexico.
| | - Pierre Baldi
- Department of Computer Science, Institute for Genomics and Bioinformatics, and Center for Machine Learning and Intelligent Systems, University of California, Irvine, CA 92697, USA.
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9
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Baranes K, Hibsh D, Cohen S, Yamin T, Efroni S, Sharoni A, Shefi O. Comparing Transcriptome Profiles of Neurons Interfacing Adjacent Cells and Nanopatterned Substrates Reveals Fundamental Neuronal Interactions. NANO LETTERS 2019; 19:1451-1459. [PMID: 30704243 DOI: 10.1021/acs.nanolett.8b03879] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Developing neuronal axons are directed by chemical and physical signals toward a myriad of target cells. According to current dogma, the resulting network architecture is critically shaped by electrical interconnections, the synapses; however, key mechanisms translating neuronal interactions into neuronal growth behavior during network formation are still unresolved. To elucidate these mechanisms, we examined neurons interfacing nanopatterned substrates and compared them to natural interneuron interactions. We grew similar neuronal populations under three connectivity conditions, (1) the neurons are isolated, (2) the neurons are interconnected, and (3) the neurons are connected only to artificial substrates, then quantitatively compared both the cell morphologies and the transcriptome-expression profiles. Our analysis shows that whereas axon-guidance signaling pathways in isolated neurons are predominant, in isolated neurons interfacing nanotopography, these pathways are downregulated, similar to the interconnected neurons. Moreover, in nanotopography, interfacing neuron genes related to synaptogenesis and synaptic regulation are highly expressed, that is, again resembling the behavior of interconnected neurons. These molecular findings demonstrate that interactions with nanotopographies, although not leading to electrical coupling, play a comparable functional role in two major routes, neuronal guidance and network formation, with high relevance to the design of regenerative interfaces.
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Affiliation(s)
- Koby Baranes
- Faculty of Engineering , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Dror Hibsh
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Faculty of Life Sciences , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Sharon Cohen
- Faculty of Engineering , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Gonda Multidisciplinary Brain Research Center , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Tony Yamin
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Department of Physics , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Sol Efroni
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Faculty of Life Sciences , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Amos Sharoni
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Department of Physics , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Orit Shefi
- Faculty of Engineering , Bar-Ilan University , Ramat-Gan 5290002 , Israel
- Bar-Ilan Institute of Nanotechnology and Advanced Materials , Bar-Ilan University , Ramat-Gan 5290002 , Israel
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10
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Abstract
As the nervous system evolved from the diffused to centralised form, the neurones were joined by the appearance of the supportive cells, the neuroglia. Arguably, these non-neuronal cells evolve into a more diversified cell family than the neurones are. The first ancestral neuroglia appeared in flatworms being mesenchymal in origin. In the nematode C. elegans proto-astrocytes/supportive glia of ectodermal origin emerged, albeit the ensheathment of axons by glial cells occurred later in prawns. The multilayered myelin occurred by convergent evolution of oligodendrocytes and Schwann cells in vertebrates above the jawless fishes. Nutritive partitioning of the brain from the rest of the body appeared in insects when the hemolymph-brain barrier, a predecessor of the blood-brain barrier was formed. The defensive cellular mechanism required specialisation of bona fide immune cells, microglia, a process that occurred in the nervous system of leeches, bivalves, snails, insects and above. In ascending phylogeny, new type of glial cells, such as scaffolding radial glia, appeared and as the bran sizes enlarged, the glia to neurone ratio increased. Humans possess some unique glial cells not seen in other animals.
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11
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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: 33] [Impact Index Per Article: 5.5] [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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12
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Welzel G, Schuster S. Long-term potentiation in an innexin-based electrical synapse. Sci Rep 2018; 8:12579. [PMID: 30135467 PMCID: PMC6105662 DOI: 10.1038/s41598-018-30966-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/09/2018] [Indexed: 11/08/2022] Open
Abstract
Electrical synapses are formed by two unrelated gap junction protein families, the primordial innexins (invertebrates) or the connexins (vertebrates). Although molecularly different, innexin- and connexin-based electrical synapses are strikingly similar in their membrane topology. However, it remains unclear if this similarity extends also to more sophisticated functions such as long-term potentiation which is only known in connexin-based synapses. Here we show that this capacity is not unique to connexin-based synapses. Using a method that allowed us to quantitatively measure gap-junction conductance we provide the first and unequivocal evidence of long-term potentiation in an innexin-based electrical synapse. Our findings suggest that long-term potentiation is a property that has likely existed already in ancestral gap junctions. They therefore could provide a highly potent system to dissect shared molecular mechanisms of electrical synapse plasticity.
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Affiliation(s)
- Georg Welzel
- Department of Animal Physiology, University of Bayreuth, 95440, Bayreuth, Germany.
| | - Stefan Schuster
- Department of Animal Physiology, University of Bayreuth, 95440, Bayreuth, Germany.
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13
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Northcutt AJ, Fischer EK, Puhl JG, Mesce KA, Schulz DJ. An annotated CNS transcriptome of the medicinal leech, Hirudo verbana: De novo sequencing to characterize genes associated with nervous system activity. PLoS One 2018; 13:e0201206. [PMID: 30028871 PMCID: PMC6054404 DOI: 10.1371/journal.pone.0201206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/10/2018] [Indexed: 11/19/2022] Open
Abstract
The medicinal leech is one of the most venerated model systems for the study of fundamental nervous system principles, ranging from single-cell excitability to complex sensorimotor integration. Yet, molecular analyses have yet to be extensively applied to complement the rich history of electrophysiological study that this animal has received. Here, we generated the first de novo transcriptome assembly from the entire central nervous system of Hirudo verbana, with the goal of providing a molecular resource, as well as to lay the foundation for a comprehensive discovery of genes fundamentally important for neural function. Our assembly generated 107,704 contigs from over 900 million raw reads. Of these 107,704 contigs, 39,047 (36%) were annotated using NCBI's validated RefSeq sequence database. From this annotated central nervous system transcriptome, we began the process of curating genes related to nervous system function by identifying and characterizing 126 unique ion channel, receptor, transporter, and enzyme contigs. Additionally, we generated sequence counts to estimate the relative abundance of each identified ion channel and receptor contig in the transcriptome through Kallisto mapping. This transcriptome will serve as a valuable community resource for studies investigating the molecular underpinnings of neural function in leech and provide a reference for comparative analyses.
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Affiliation(s)
- Adam J. Northcutt
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri, United States of America
| | - Eva K. Fischer
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Joshua G. Puhl
- Department of Entomology and Graduate Program in Neuroscience, University of Minnesota, Saint Paul, Minnesota, United States of America
| | - Karen A. Mesce
- Department of Entomology and Graduate Program in Neuroscience, University of Minnesota, Saint Paul, Minnesota, United States of America
| | - David J. Schulz
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri, United States of America
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14
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Liu Z, Wang Y, Tong X, Su Y, Yang L, Wang D, Zhao Y. De novo assembly and comparative transcriptome characterization of Poecilobdella javanica provide insight into blood feeding of medicinal leeches. Mol Omics 2018; 14:352-361. [DOI: 10.1039/c8mo00098k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Leeches (family Hirudinidae) are classic model invertebrates used in diverse clinical treatments, such as reconstructive microsurgery, hypertension, and gangrene treatment.
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Affiliation(s)
- Zichao Liu
- Department of Life Science & Technology, Kunming University, Kunming Key Laboratory of Hydroecology Restoration of Dianchi Lake, Key Laboratory of Special Biological Resource Development & Utilization of Universities in Yunnan Province
- Kunming
- China
| | - Yanjie Wang
- Jules Stein Eye Institute, Department of Ophthalmology, University of California
- Los Angeles
- USA
| | - Xiangrong Tong
- Department of Life Science & Technology, Kunming University, Kunming Key Laboratory of Hydroecology Restoration of Dianchi Lake, Key Laboratory of Special Biological Resource Development & Utilization of Universities in Yunnan Province
- Kunming
- China
| | - Yuan Su
- Department of Life Science & Technology, Kunming University, Kunming Key Laboratory of Hydroecology Restoration of Dianchi Lake, Key Laboratory of Special Biological Resource Development & Utilization of Universities in Yunnan Province
- Kunming
- China
| | - Lijiang Yang
- Department of Life Science & Technology, Kunming University, Kunming Key Laboratory of Hydroecology Restoration of Dianchi Lake, Key Laboratory of Special Biological Resource Development & Utilization of Universities in Yunnan Province
- Kunming
- China
| | - Debin Wang
- Department of Life Science & Technology, Kunming University, Kunming Key Laboratory of Hydroecology Restoration of Dianchi Lake, Key Laboratory of Special Biological Resource Development & Utilization of Universities in Yunnan Province
- Kunming
- China
| | - Yuqi Zhao
- Department of Integrative Biology and Physiology, University of California, Los Angeles
- Los Angeles
- USA
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15
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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16
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 916] [Impact Index Per Article: 152.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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17
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Otopalik AG, Lane B, Schulz DJ, Marder E. Innexin expression in electrically coupled motor circuits. Neurosci Lett 2017; 695:19-24. [PMID: 28711343 PMCID: PMC5767152 DOI: 10.1016/j.neulet.2017.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/22/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022]
Abstract
The many roles of innexins, the molecules that form gap junctions in invertebrates, have been explored in numerous species. Here, we present a summary of innexin expression and function in two small, central pattern generating circuits found in crustaceans: the stomatogastric ganglion and the cardiac ganglion. The two ganglia express multiple innexin genes, exhibit varying combinations of symmetrical and rectifying gap junctions, as well as gap junctions within and across different cell types. Past studies have revealed correlations in ion channel and innexin expression in coupled neurons, as well as intriguing functional relationships between ion channel conductances and electrical coupling. Together, these studies suggest a putative role for innexins in correlating activity between coupled neurons at the levels of gene expression and physiological activity during development and in the adult animal.
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Affiliation(s)
- Adriane G Otopalik
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA.
| | - Brian Lane
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - David J Schulz
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Eve Marder
- Volen Center and Biology Department, Brandeis University, Waltham, MA 02454, USA
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18
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Beyer EC, Berthoud VM. Gap junction gene and protein families: Connexins, innexins, and pannexins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:5-8. [PMID: 28559187 DOI: 10.1016/j.bbamem.2017.05.016] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 05/18/2017] [Accepted: 05/25/2017] [Indexed: 02/08/2023]
Abstract
Gap junction channels facilitate the intercellular exchange of ions and small molecules. While this process is critical to all multicellular organisms, the proteins that form gap junction channels are not conserved. Vertebrate gap junctions are formed by connexins, while invertebrate gap junctions are formed by innexins. Interestingly, vertebrates and lower chordates contain innexin homologs, the pannexins, which also form channels, but rarely (if ever) make intercellular channels. While the connexin and the innexin/pannexin polypeptides do not share significant sequence similarity, all three of these protein families share a similar membrane topology and some similarities in quaternary structure. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Eric C Beyer
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States.
| | - Viviana M Berthoud
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, United States
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19
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Miller AC, Whitebirch AC, Shah AN, Marsden KC, Granato M, O'Brien J, Moens CB. A genetic basis for molecular asymmetry at vertebrate electrical synapses. eLife 2017; 6. [PMID: 28530549 PMCID: PMC5462537 DOI: 10.7554/elife.25364] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 05/20/2017] [Indexed: 01/18/2023] Open
Abstract
Neural network function is based upon the patterns and types of connections made between neurons. Neuronal synapses are adhesions specialized for communication and they come in two types, chemical and electrical. Communication at chemical synapses occurs via neurotransmitter release whereas electrical synapses utilize gap junctions for direct ionic and metabolic coupling. Electrical synapses are often viewed as symmetrical structures, with the same components making both sides of the gap junction. By contrast, we show that a broad set of electrical synapses in zebrafish, Danio rerio, require two gap-junction-forming Connexins for formation and function. We find that one Connexin functions presynaptically while the other functions postsynaptically in forming the channels. We also show that these synapses are required for the speed and coordination of escape responses. Our data identify a genetic basis for molecular asymmetry at vertebrate electrical synapses and show they are required for appropriate behavioral performance. DOI:http://dx.doi.org/10.7554/eLife.25364.001
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Affiliation(s)
- Adam C Miller
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Alex C Whitebirch
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Arish N Shah
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Kurt C Marsden
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, United States
| | - Michael Granato
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, United States
| | - John O'Brien
- Department of Ophthalmology and Visual Science, McGovern Medical School, University of Texas Health Sciences Center at Houston, Houston, United States
| | - Cecilia B Moens
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
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20
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Baker MW, Macagno ER. Gap junction proteins and the wiring (Rewiring) of neuronal circuits. Dev Neurobiol 2017; 77:575-586. [PMID: 27512961 DOI: 10.1002/dneu.22429] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 08/01/2016] [Accepted: 08/08/2016] [Indexed: 11/11/2022]
Abstract
The unique morphology and pattern of synaptic connections made by a neuron during development arise in part by an extended period of growth in which cell-cell interactions help to sculpt the arbor into its final shape, size, and participation in different synaptic networks. Recent experiments highlight a guiding role played by gap junction proteins in controlling this process. Ectopic and overexpression studies in invertebrates have revealed that the selective expression of distinct gap junction genes in neurons and glial cells is sufficient to establish selective new connections in the central nervous systems of the leech (Firme et al. [2012]: J Neurosci 32:14265-14270), the nematode (Rabinowitch et al. [2014]: Nat Commun 5:4442), and the fruit fly (Pézier et al., 2016: PLoS One 11:e0152211). We present here an overview of this work and suggest that gap junction proteins, in addition to their synaptic/communicative functions, have an instructive role as recognition and adhesion factors. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 575-586, 2017.
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Affiliation(s)
- Michael W Baker
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, 92093
| | - Eduardo R Macagno
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, 92093
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21
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Szczupak L. Functional contributions of electrical synapses in sensory and motor networks. Curr Opin Neurobiol 2016; 41:99-105. [PMID: 27649466 DOI: 10.1016/j.conb.2016.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/29/2016] [Accepted: 08/31/2016] [Indexed: 11/28/2022]
Abstract
Intercellular interactions in the nervous system are mediated by two types of dedicated structural arrangements: electrical and chemical synapses. Several characteristics distinguish these two mechanisms of communication, such as speed, reliability and the fact that electrical synapses are, potentially, bidirectional. Given these properties, electrical synapses can subserve, in addition to synchrony, three main interrelated network functions: signal amplification, noise reduction and/or coincidence detection. Specific network motifs in sensory and motor systems of invertebrates and vertebrates illustrate how signal transmission through electrical junctions contributes to a complex processing of information.
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Affiliation(s)
- Lidia Szczupak
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBYNE UBA-CONICET, Pabellón II, piso 2. Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
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22
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De-La-Rosa Tovar A, Mishra PK, De-Miguel FF. On the Basis of Synaptic Integration Constancy during Growth of a Neuronal Circuit. Front Cell Neurosci 2016; 10:198. [PMID: 27587998 PMCID: PMC4989888 DOI: 10.3389/fncel.2016.00198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 07/29/2016] [Indexed: 01/19/2023] Open
Abstract
We studied how a neuronal circuit composed of two neuron types connected by chemical and electrical synapses maintains constant its integrative capacities as neurons grow. For this we combined electrophysiological experiments with mathematical modeling in pairs of electrically-coupled Retzius neurons from postnatal to adult leeches. The electrically-coupled dendrites of both Retzius neurons receive a common chemical input, which produces excitatory postsynaptic potentials (EPSPs) with varying amplitudes. Each EPSP spreads to the soma, but also crosses the electrical synapse to arrive at the soma of the coupled neuron. The leak of synaptic current across the electrical synapse reduces the amplitude of the EPSPs in proportion to the coupling ratio. In addition, summation of EPSPs generated in both neurons generates the baseline action potentials of these serotonergic neurons. To study how integration is adjusted as neurons grow, we first studied the characteristics of the chemical and electrical connections onto the coupled dendrites of neuron pairs with soma diameters ranging from 21 to 75 μm. Then by feeding a mathematical model with the neuronal voltage responses to pseudorandom noise currents we obtained the values of the coupling ratio, the membrane resistance of the soma (rm) and dendrites (rdend), the space constant (λ) and the characteristic dendritic length (L = l/λ). We found that the EPSPs recorded from the somata were similar regardless on the neuron size. However, the amplitude of the EPSPs and the firing frequency of the neurons were inversely proportional to the coupling ratio of the neuron pair, which also was independent from the neuronal size. This data indicated that the integrative constancy relied on the passive membrane properties. We show that the growth of Retzius neurons was compensated by increasing the membrane resistance of the dendrites and therefore the λ value. By solely increasing the dendrite resistance this circuit maintains constant its integrative capacities as its neurons grow.
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Affiliation(s)
- Adriana De-La-Rosa Tovar
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México México, D.F., Mexico
| | - Prashant K Mishra
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México México, D.F., Mexico
| | - Francisco F De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México México, D.F., Mexico
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23
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Wang SP, Chen FY, Dong LX, Zhang YQ, Chen HY, Qiao K, Wang KJ. A novel innexin2 forming membrane hemichannel exhibits immune responses and cell apoptosis in Scylla paramamosain. FISH & SHELLFISH IMMUNOLOGY 2015; 47:485-499. [PMID: 26384843 DOI: 10.1016/j.fsi.2015.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 09/06/2015] [Accepted: 09/14/2015] [Indexed: 06/05/2023]
Abstract
Innexins are a class of transmembrane proteins that are important for embryonic development, morphogenesis and electrical synapse formation. In the present study, a novel innexin2 gene from Scylla paramamosain was named Sp-inx2 and characterized. The complete cDNA and genomic DNA sequences of Sp-inx2 were revealed. Sp-inx2 mRNA transcripts were distributed in various tissues of S. paramamosain and were most abundant in the hemocytes. The Sp-inx2 was significantly upregulated in hemocyte, gill and hepatopancreas tissues with the challenge of either Vibrio alginolyticus, Vibrio parahaemolyticus or lipopolysaccharides (LPSs) when analyzed at 3 and 6 h using quantitative real-time PCR, suggesting that it could activate an immune response against the challenge of LPSs or Vibrio species. Using the chemical inhibitors carbenoxolone and probenecid, the absorption of the fluorescent dye Lucifer yellow decreased in the primary cultured hemocytes of crabs, thus confirming that hemichannels composed of Sp-inx2 existed in the crab hemocytes. With LPS stimulation, the level of mRNA transcripts and protein expression of Sp-inx2 in the same cultured hemocytes gradually increased from 6 to 48 h, while the activity of hemichannels was down-regulated at 6 and 12 h, demonstrating that LPSs could modulate the absorption activity of hemichannels in addition to its upregulation of Sp-inx2 gene expression. Furthermore, the dye uptake rate in HeLa cells in which Sp-inx2 was ectopically expressed increased dramatically but the increase was significantly down-regulated with the addition of 50 μg mL(-1) LPS, suggesting that the LPS stimulation could effectively reduce the activity of hemichannels. Interestingly, with the ectopic expression of Sp-inx2 in HeLa and EPC cells, apoptosis spontaneously occurred in both cultured cell lines when detected using TUNEL assay. In summary, a new Sp-inx2 gene was first characterized in a marine animal S. paramamosain and it had a function associated with immune response and cell apoptosis.
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Affiliation(s)
- Shu-Ping Wang
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China
| | - Fang-Yi Chen
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China; Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources, Xiamen University, Xiamen, Fujian, PR China; Fujian Engineering Laboratory of Marine Bioproducts and Technology, Xiamen University, Xiamen, Fujian, PR China
| | - Li-Xia Dong
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China
| | - Ya-Qun Zhang
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China
| | - Hui-Yun Chen
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China; Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources, Xiamen University, Xiamen, Fujian, PR China; Fujian Engineering Laboratory of Marine Bioproducts and Technology, Xiamen University, Xiamen, Fujian, PR China
| | - Kun Qiao
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China
| | - Ke-Jian Wang
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China; Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources, Xiamen University, Xiamen, Fujian, PR China; Fujian Engineering Laboratory of Marine Bioproducts and Technology, Xiamen University, Xiamen, Fujian, PR China.
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24
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Hibsh D, Schori H, Efroni S, Shefi O. De novo transcriptome assembly databases for the central nervous system of the medicinal leech. Sci Data 2015; 2:150015. [PMID: 25977819 PMCID: PMC4412018 DOI: 10.1038/sdata.2015.15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/03/2015] [Indexed: 01/17/2023] Open
Abstract
The study of non-model organisms stands to benefit greatly from genetic and genomic data. For a better understanding of the molecular mechanisms driving neuronal development, and to characterize the entire leech Hirudo medicinalis central nervous system (CNS) transcriptome we combined Trinity for de-novo assembly and Illumina HiSeq2000 for RNA-Seq. We present a set of 73,493 de-novo assembled transcripts for the leech, reconstructed from RNA collected, at a single ganglion resolution, from the CNS. This set of transcripts greatly enriches the available data for the leech. Here, we share two databases, such that each dataset allows a different type of search for candidate homologues. The first is the raw set of assembled transcripts. This set allows a sequence-based search. A comprehensive analysis of which revealed 22,604 contigs with high e-values, aligned versus the Swiss-Prot database. This analysis enabled the production of the second database, which includes correlated sequences to annotated transcript names, with the confidence of BLAST best hit.
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Affiliation(s)
- Dror Hibsh
- Faculty of Life Sciences, Bar Ilan University, Ramat Gan 5290002, Israel
- Faculty of Engineering, Bar Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, Ramat Gan 5290002, Israel
| | - Hadas Schori
- Faculty of Engineering, Bar Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, Ramat Gan 5290002, Israel
| | - Sol Efroni
- Faculty of Life Sciences, Bar Ilan University, Ramat Gan 5290002, Israel
| | - Orit Shefi
- Faculty of Engineering, Bar Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, Ramat Gan 5290002, Israel
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25
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Ounzain S, Pezzuto I, Micheletti R, Burdet F, Sheta R, Nemir M, Gonzales C, Sarre A, Alexanian M, Blow MJ, May D, Johnson R, Dauvillier J, Pennacchio LA, Pedrazzini T. Functional importance of cardiac enhancer-associated noncoding RNAs in heart development and disease. J Mol Cell Cardiol 2014; 76:55-70. [PMID: 25149110 PMCID: PMC4445080 DOI: 10.1016/j.yjmcc.2014.08.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 08/07/2014] [Accepted: 08/07/2014] [Indexed: 01/17/2023]
Abstract
The key information processing units within gene regulatory networks are enhancers. Enhancer activity is associated with the production of tissue-specific noncoding RNAs, yet the existence of such transcripts during cardiac development has not been established. Using an integrated genomic approach, we demonstrate that fetal cardiac enhancers generate long noncoding RNAs (lncRNAs) during cardiac differentiation and morphogenesis. Enhancer expression correlates with the emergence of active enhancer chromatin states, the initiation of RNA polymerase II at enhancer loci and expression of target genes. Orthologous human sequences are also transcribed in fetal human hearts and cardiac progenitor cells. Through a systematic bioinformatic analysis, we identified and characterized, for the first time, a catalog of lncRNAs that are expressed during embryonic stem cell differentiation into cardiomyocytes and associated with active cardiac enhancer sequences. RNA-sequencing demonstrates that many of these transcripts are polyadenylated, multi-exonic long noncoding RNAs. Moreover, knockdown of two enhancer-associated lncRNAs resulted in the specific downregulation of their predicted target genes. Interestingly, the reactivation of the fetal gene program, a hallmark of the stress response in the adult heart, is accompanied by increased expression of fetal cardiac enhancer transcripts. Altogether, these findings demonstrate that the activity of cardiac enhancers and expression of their target genes are associated with the production of enhancer-derived lncRNAs.
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Affiliation(s)
- Samir Ounzain
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland.
| | - Iole Pezzuto
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Rudi Micheletti
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Frédéric Burdet
- VitalIT, Swiss Institute of Bioinformatics, University of Lausanne, Lausanne, Switzerland
| | - Razan Sheta
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Mohamed Nemir
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Christine Gonzales
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Alexandre Sarre
- Cardiovascular Assessment Facility, University of Lausanne, Lausanne, Switzerland
| | - Michael Alexanian
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland
| | - Matthew J Blow
- Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; US Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Dalit May
- Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; US Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Rory Johnson
- Bioinformatics and Genomics Group, Centre for Genomic Regulation, Barcelona, Spain
| | - Jérôme Dauvillier
- VitalIT, Swiss Institute of Bioinformatics, University of Lausanne, Lausanne, Switzerland
| | - Len A Pennacchio
- Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; US Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Department of Medicine, University of Lausanne Medical School, Lausanne, Switzerland.
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Shruti S, Schulz DJ, Lett KM, Marder E. Electrical coupling and innexin expression in the stomatogastric ganglion of the crab Cancer borealis. J Neurophysiol 2014; 112:2946-58. [PMID: 25210156 DOI: 10.1152/jn.00536.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Gap junctions are intercellular channels that allow for the movement of small molecules and ions between the cytoplasm of adjacent cells and form electrical synapses between neurons. In invertebrates, the gap junction proteins are coded for by the innexin family of genes. The stomatogastric ganglion (STG) in the crab Cancer borealis contains a small number of identified and electrically coupled neurons. We identified Innexin 1 (Inx1), Innexin 2 (Inx2), Innexin 3 (Inx3), Innexin 4 (Inx4), Innexin 5 (Inx5), and Innexin 6 (Inx6) members of the C. borealis innexin family. We also identified six members of the innexin family from the lobster Homarus americanus transcriptome. These innexins show significant sequence similarity to other arthropod innexins. Using in situ hybridization and reverse transcriptase-quantitative PCR (RT-qPCR), we determined that all the cells in the crab STG express multiple innexin genes. Electrophysiological recordings of coupling coefficients between identified pairs of pyloric dilator (PD) cells and PD-lateral posterior gastric (LPG) neurons show that the PD-PD electrical synapse is nonrectifying while the PD-LPG synapse is apparently strongly rectifying.
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Affiliation(s)
- Sonal Shruti
- Volen Center and Biology Department, Brandeis University, Waltham, Massachusetts; and
| | - David J Schulz
- Division of Biological Sciences, University of Missouri at Columbia, Columbia, Missouri
| | - Kawasi M Lett
- Division of Biological Sciences, University of Missouri at Columbia, Columbia, Missouri
| | - Eve Marder
- Volen Center and Biology Department, Brandeis University, Waltham, Massachusetts; and
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Randel N, Asadulina A, Bezares-Calderón LA, Verasztó C, Williams EA, Conzelmann M, Shahidi R, Jékely G. Neuronal connectome of a sensory-motor circuit for visual navigation. eLife 2014; 3. [PMID: 24867217 PMCID: PMC4059887 DOI: 10.7554/elife.02730] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/25/2014] [Indexed: 12/11/2022] Open
Abstract
Animals use spatial differences in environmental light levels for visual navigation; however, how light inputs are translated into coordinated motor outputs remains poorly understood. Here we reconstruct the neuronal connectome of a four-eye visual circuit in the larva of the annelid Platynereis using serial-section transmission electron microscopy. In this 71-neuron circuit, photoreceptors connect via three layers of interneurons to motorneurons, which innervate trunk muscles. By combining eye ablations with behavioral experiments, we show that the circuit compares light on either side of the body and stimulates body bending upon left-right light imbalance during visual phototaxis. We also identified an interneuron motif that enhances sensitivity to different light intensity contrasts. The Platynereis eye circuit has the hallmarks of a visual system, including spatial light detection and contrast modulation, illustrating how image-forming eyes may have evolved via intermediate stages contrasting only a light and a dark field during a simple visual task. DOI:http://dx.doi.org/10.7554/eLife.02730.001 Many animals show automatic responses to light, from moths, which are attracted to light sources, to cockroaches, which are repelled by them. This phenomenon, known as phototaxis, is thought to help animals navigate through their environment. It is an evolutionarily ancient behavior, as revealed by its widespread presence in the animal kingdom. One animal with a simple visual system for phototactic behavior is the marine worm Platynereis dumerilii. Platynereis is a segmented worm (annelid) with four eyes on the top of its head, two on the right and two on the left. Exposure to light triggers the contraction of muscles that run along the length of the body, causing the worm to bend and thus change the direction it is swimming in. Now, using a combination of high-resolution microscopy and behavioral experiments in larvae, Randel et al. have mapped the neural circuits underlying the worm's phototactic behavior. A 3-day-old Platynereis larva was sectioned to produce almost 1700 slices, each less than 50 nanometers thick, which were then viewed under a transmission electron microscope. By tracing individual neurons from one slice to the next, it was possible to reconstruct the entire visual system and all of its connections. This ‘visual connectome’ consisted of 71 neurons—21 light-sensitive cells, 42 interneurons, and 8 muscle-controlling motorneurons—organized into a circuit with 1106 connections. Shining light onto living larvae triggered phototaxis, with some larvae consistently swimming towards the light and others away from it. Using a laser to destroy all four eyes abolished this behavior, as did the removal of both eyes on either side of the head. By contrast, removing one eye from each side had no effect. This was because these larvae were still able to simultaneously compare the amounts of light reaching the left and right sides of their body, and to use any difference in these levels as a directional cue to guide swimming. By revealing the circuitry underlying phototaxis in a marine worm, Randel et al. have provided clues to the mechanisms that support this behavior in other species. The data could also provide insights into the processes that contributed to the evolution of more complex visual systems. DOI:http://dx.doi.org/10.7554/eLife.02730.002
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Affiliation(s)
- Nadine Randel
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Albina Asadulina
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | | | - Csaba Verasztó
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | | | | | - Réza Shahidi
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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28
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Innexin and pannexin channels and their signaling. FEBS Lett 2014; 588:1396-402. [PMID: 24632288 DOI: 10.1016/j.febslet.2014.03.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 03/06/2014] [Indexed: 01/24/2023]
Abstract
Innexins are bifunctional membrane proteins in invertebrates, forming gap junctions as well as non-junctional membrane channels (innexons). Their vertebrate analogues, the pannexins, have not only lost the ability to form gap junctions but are also prevented from it by glycosylation. Pannexins appear to form only non-junctional membrane channels (pannexons). The membrane channels formed by pannexins and innexins are similar in their biophysical and pharmacological properties. Innexons and pannexons are permeable to ATP, are present in glial cells, and are involved in activation of microglia by calcium waves in glia. Directional movement and accumulation of microglia following nerve injury, which has been studied in the leech which has unusually large glial cells, involves at least 3 signals: ATP is the "go" signal, NO is the "where" signal and arachidonic acid is a "stop" signal.
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29
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Electrical synapses and their functional interactions with chemical synapses. Nat Rev Neurosci 2014; 15:250-63. [PMID: 24619342 DOI: 10.1038/nrn3708] [Citation(s) in RCA: 306] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Brain function relies on the ability of neurons to communicate with each other. Interneuronal communication primarily takes place at synapses, where information from one neuron is rapidly conveyed to a second neuron. There are two main modalities of synaptic transmission: chemical and electrical. Far from functioning independently and serving unrelated functions, mounting evidence indicates that these two modalities of synaptic transmission closely interact, both during development and in the adult brain. Rather than conceiving synaptic transmission as either chemical or electrical, this article emphasizes the notion that synaptic transmission is both chemical and electrical, and that interactions between these two forms of interneuronal communication might be required for normal brain development and function.
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30
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Baker MW, Macagno ER. Control of neuronal morphology and connectivity: Emerging developmental roles for gap junctional proteins. FEBS Lett 2014; 588:1470-9. [DOI: 10.1016/j.febslet.2014.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 02/10/2014] [Accepted: 02/12/2014] [Indexed: 11/25/2022]
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Abstract
The pannexins (Panxs) are a family of chordate proteins homologous to the invertebrate gap junction forming proteins named innexins. Three distinct Panx paralogs (Panx1, Panx2, and Panx3) are shared among the major vertebrate phyla, but they appear to have suppressed (or even lost) their ability to directly couple adjacent cells. Connecting the intracellular and extracellular compartments is now widely accepted as Panx's primary function, facilitating the passive movement of ions and small molecules along electrochemical gradients. The tissue distribution of the Panxs ranges from pervasive to very restricted, depending on the paralog, and are often cell type-specific and/or developmentally regulated within any given tissue. In recent years, Panxs have been implicated in an assortment of physiological and pathophysiological processes, particularly with respect to ATP signaling and inflammation, and they are now considered to be a major player in extracellular purinergic communication. The following is a comprehensive review of the Panx literature, exploring the historical events leading up to their discovery, outlining our current understanding of their biochemistry, and describing the importance of these proteins in health and disease.
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Affiliation(s)
- Stephen R Bond
- Genome Technology Branch, Division of Intramural Research, National Human Genome Research Institute, National Institutes of Health Bethesda, MD, USA ; Department of Cellular and Physiological Science, Life Sciences Institute, University of British Columbia Vancouver, BC, Canada
| | - Christian C Naus
- Department of Cellular and Physiological Science, Life Sciences Institute, University of British Columbia Vancouver, BC, Canada
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Abstract
Oppositely directed projections of some homologous neurons in the developing CNS of the medicinal leech (Hirudo verbana), such as the AP cells, undergo a form of contact-dependent homolog avoidance. Embryonic APs extend axons within the connective nerve toward adjacent ganglia, in which they meet and form gap junctions (GJs) with the oppositely directed axons of their segmental homologs, stop growing, and are later permanently retracted (Wolszon et al., 1994a,b). However, early deletion of an AP neuron leads to resumed growth and permanent maintenance of the projections of neighboring APs. Here we test the hypothesis that a GJ-based signaling mechanism is responsible for this instance of homolog avoidance. We demonstrate that selective knockdown of GJ gene Hve-inx1 expression in single embryonic APs, by expressing a short-hairpin interfering RNA, leads to continued growth of the projections of the cell toward, into, and beyond adjacent ganglia. Moreover, the projections of the APs in adjacent ganglia also resume growth, mimicking their responses to cell deletion. Continued growth was also observed when two different INX1 mutant transgenes that abolish dye coupling between APs were expressed. These include a mutant transgene that effectively downregulates all GJ plaques that include the INX1 protein and a closed channel INX1 mutant that retains the adhesive cellular binding characteristic of INX1 GJs but not the open channel pore function. Our results add GJ intercellular communication to the list of molecular signaling mechanisms that can act as mediators of growth-inhibiting cell-cell interactions that define the topography of neuronal arbors.
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Titlow J, Majeed ZR, Nicholls JG, Cooper RL. Intracellular recording, sensory field mapping, and culturing identified neurons in the leech, Hirudo medicinalis. J Vis Exp 2013:e50631. [PMID: 24299987 PMCID: PMC3969890 DOI: 10.3791/50631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The freshwater leech, Hirudo medicinalis, is a versatile model organism that has been used to address scientific questions in the fields of neurophysiology, neuroethology, and developmental biology. The goal of this report is to consolidate experimental techniques from the leech system into a single article that will be of use to physiologists with expertise in other nervous system preparations, or to biology students with little or no electrophysiology experience. We demonstrate how to dissect the leech for recording intracellularly from identified neural circuits in the ganglion. Next we show how individual cells of known function can be removed from the ganglion to be cultured in a Petri dish, and how to record from those neurons in culture. Then we demonstrate how to prepare a patch of innervated skin to be used for mapping sensory or motor fields. These leech preparations are still widely used to address basic electrical properties of neural networks, behavior, synaptogenesis, and development. They are also an appropriate training module for neuroscience or physiology teaching laboratories.
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Affiliation(s)
- Josh Titlow
- Department of Biology, University of Kentucky
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Hibsh D, Schori H, Efroni S, Shefi O. Spatial regulation dominates gene function in the ganglia chain. ACTA ACUST UNITED AC 2013; 30:310-6. [PMID: 24085568 DOI: 10.1093/bioinformatics/btt570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
MOTIVATION To understand the molecular mechanisms of neurons, it is imperative to identify genomic dissimilarities within the heterogeneity of the neural system. This is especially true for neuronal disorders in which spatial considerations are of critical nature. For this purpose, Hirudo medicinalis provides here an ideal system in which we are able to follow gene expression along the central nervous system, to affiliate location with gene behavior. RESULTS In all, 221.1 million high-quality short reads were sequenced on the Illumina Hiseq2000 platform at the single ganglion level. Thereafter, a de novo assembly was performed using two state-of-the-art assemblers, Trinity and Trans-ABySS, to reconstruct a comprehensive de novo transcriptome. Classification of Trinity and Trans-ABySS transcripts produced a non-redundant set of 76 845 and 268 355 transcripts (>200 bp), respectively. Remarkably, using Trinity, 82% of the published medicinal leech messenger RNAs was identified. For the innexin family, all of the 21 recently reported genes were identified. Spatial regulation analysis across three ganglia throughout the entire central nervous system revealed distinct patterns of gene expression. These transcriptome data were combined with expression distribution to produce a spatio-transcripto map along the ganglia chain. This study provides a resource for gene discovery and gene regulation in future studies.
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Affiliation(s)
- Dror Hibsh
- Faculty of Life Sciences, Faculty of Engineering and Institute of Nanotechnologies and Advanced Materials, Bar Ilan University, Ramat Gan, Israel 52900
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35
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Yazdani N, Firme CP, Macagno ER, Baker MW. Expression of a dominant negative mutant innexin in identified neurons and glial cells reveals selective interactions among gap junctional proteins. Dev Neurobiol 2013; 73:571-86. [DOI: 10.1002/dneu.22082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/25/2013] [Accepted: 02/26/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Neema Yazdani
- Section of Cell and Developmental Biology; University of California; San Diego La Jolla; California; 92093
| | - Constantine P. Firme
- Section of Cell and Developmental Biology; University of California; San Diego La Jolla; California; 92093
| | - Eduardo R. Macagno
- Section of Cell and Developmental Biology; University of California; San Diego La Jolla; California; 92093
| | - Michael W. Baker
- Section of Cell and Developmental Biology; University of California; San Diego La Jolla; California; 92093
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36
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Jabeen S, Thirumalai V. Distribution of the gap junction protein connexin 35 in the central nervous system of developing zebrafish larvae. Front Neural Circuits 2013; 7:91. [PMID: 23717264 PMCID: PMC3653060 DOI: 10.3389/fncir.2013.00091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 04/23/2013] [Indexed: 11/13/2022] Open
Abstract
Gap junctions are membrane specializations that allow the passage of ions and small molecules from one cell to another. In vertebrates, connexins are the protein subunits that assemble to form gap junctional plaques. Connexin-35 (Cx35) is the fish ortholog of mammalian Cx36, which is enriched in the retina and the brain and has been shown to form neuronal gap junctions. As a first step toward understanding the role of neuronal gap junctions in central nervous system (CNS) development, we describe here the distribution of Cx35 in the CNS during zebrafish development. Cx35 expression is first seen at 1 day post fertilization (dpf) along cell boundaries throughout the nervous system. At 2 dpf, Cx35 immunoreactivity appears in commissures and fiber tracts throughout the CNS and along the edges of the tectal neuropil. In the rhombencephalon, the Mauthner neurons and fiber tracts show strong Cx35 immunoreactivity. As the larva develops, the commissures and fiber tracts continue to be immunoreactive for Cx35. In addition, the area of the tectal neuropil stained increases vastly and tectal commissures are visible. Furthermore, at 4–5 dpf, Cx35 is seen in the habenulae, cerebellum and in radial glia lining the rhombencephalic ventricle. This pattern of Cx35 immunoreactivity is stable at least until 15 dpf. To test whether the Cx35 immunoreactivity seen corresponds to functional gap junctional coupling, we documented the number of dye-coupled neurons in the hindbrain. We found several dye-coupled neurons within the reticulospinal network indicating functional gap junctional connectivity in the developing zebrafish brain.
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Affiliation(s)
- Shaista Jabeen
- National Centre for Biological Sciences, NCBS-TIFR Bangalore, India
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37
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Oshima A, Matsuzawa T, Nishikawa K, Fujiyoshi Y. Oligomeric structure and functional characterization of Caenorhabditis elegans Innexin-6 gap junction protein. J Biol Chem 2013; 288:10513-21. [PMID: 23460640 DOI: 10.1074/jbc.m112.428383] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Innexin is the molecular component of invertebrate gap junctions. Here we successfully expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels and characterized the molecular dimensions and channel permeability using electron microscopy (EM) and microinjection of fluorescent dye tracers, respectively. Negative staining and thin-section EM of isolated INX-6 gap junction membranes revealed a loosely packed hexagonal lattice and a greater cross-sectional width than that of connexin26 and connexin43 (Cx43)-GFP. In gel filtration analysis, the elution profile of purified INX-6 channels in dodecyl maltoside solution exhibited a peak at ∼400 kDa that was shifted to ∼800 kDa in octyl glucose neopentyl glycol. We also obtained the class averages of purified INX-6 channels from these peak fractions by single particle analysis. The class average from the ∼800-kDa fraction showed features of the junction form with a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class averages from the ∼400-kDa fraction showed diameters of up to 140 Å in the presence of detergent micelles. These findings indicate that the purified INX-6 channels are predominantly hemichannels in dodecyl maltoside and docked junction channels in octyl glucose neopentyl glycol. Dye transfer experiments revealed that the INX-6-GFP-His channels are permeable to 3- and 10-kDa tracers, whereas no significant amounts of these tracers passed through the Cx43-GFP channels. Based on these findings, INX-6 channels have a larger overall structure and greater permeability than connexin channels.
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Affiliation(s)
- Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
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Arafah K, Croix D, Vizioli J, Desmons A, Fournier I, Salzet M. Involvement of nitric oxide through endocannabinoids release in microglia activation during the course of CNS regeneration in the medicinal leech. Glia 2013; 61:636-49. [DOI: 10.1002/glia.22462] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 12/17/2012] [Indexed: 11/06/2022]
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Ectopic expression of select innexins in individual central neurons couples them to pre-existing neuronal or glial networks that express the same innexin. J Neurosci 2013; 32:14265-70. [PMID: 23055495 DOI: 10.1523/jneurosci.2693-12.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Fifteen of the 21 innexin (Inx) genes (Hve-inx) found in the genome of the medicinal leech, Hirudo verbana, are expressed in the CNS (Kandarian et al., 2012). Two are expressed pan-neuronally, while the others are restricted in their expression to small numbers of cells, in some cases reflecting the membership of known networks of electrically coupled and dye-coupled neurons or glial cells. We report here that when Hve-inx genes characteristic of discrete coupled networks were expressed ectopically in neurons known not to express them, the experimental cells were found to become dye coupled with the other cells in that network. Hve-inx6 is normally expressed by only three neurons in each ganglion, which form strongly dye-coupled electrical connections with each other [Shortening-Coupling interneuron (S-CI) network] (Muller and Scott, 1981; Dykes and Macagno, 2006). But when Hve-inx6 was ectopically expressed in a variety of central embryonic neurons, those cells became dye coupled with the S-CI network. Similarly, Hve-inx2 is normally uniquely expressed by the ganglion's large glial cells, but when it was ectopically expressed in different central neurons, they became dye coupled to the glial cells. In contrast, overexpression of the pan-neuronal Inx genes Hve-inx1 and Hve-inx14 did not yield any novel instances of dye coupling to pre-existent neuronal networks. These results reveal that expression of certain innexins is sufficient to couple individual neurons to pre-existing networks in the CNS. We propose that a primary determinant of selective neuronal connectivity and circuit formation in the leech is the surface expression of unique subsets of gap junctional proteins.
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