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Dumas CM, St Clair RM, Lasseigne AM, Ballif BA, Ebert AM. The intracellular domain of Sema6A is essential for development of the zebrafish retina. J Cell Sci 2024; 137:jcs261469. [PMID: 38963001 DOI: 10.1242/jcs.261469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 06/24/2024] [Indexed: 07/05/2024] Open
Abstract
Semaphorin6A (Sema6A) is a repulsive guidance molecule that plays many roles in central nervous system, heart and bone development, as well as immune system responses and cell signaling in cancer. Loss of Sema6A or its receptor PlexinA2 in zebrafish leads to smaller eyes and improper retinal patterning. Here, we investigate a potential role for the Sema6A intracellular domain in zebrafish eye development and dissect which phenotypes rely on forward signaling and which rely on reverse signaling. We performed rescue experiments on zebrafish Sema6A morphants with either full-length Sema6A (Sema6A-FL) or Sema6A lacking its intracellular domain (Sema6A-ΔC). We identified that the intracellular domain is not required for eye size and retinal patterning, however it is required for retinal integrity, the number and end feet strength of Müller glia and protecting against retinal cell death. This novel function for the intracellular domain suggests a role for Sema6A reverse signaling in zebrafish eye development.
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Affiliation(s)
- Caroline M Dumas
- Department of Biology, University of Vermont, Burlington, VT 05405, USA
| | - Riley M St Clair
- Department of Biology, University of Vermont, Burlington, VT 05405, USA
| | | | - Bryan A Ballif
- Department of Biology, University of Vermont, Burlington, VT 05405, USA
| | - Alicia M Ebert
- Department of Biology, University of Vermont, Burlington, VT 05405, USA
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2
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Prieur DS, Francius C, Gaspar P, Mason CA, Rebsam A. Semaphorin-6D and Plexin-A1 Act in a Non-Cell-Autonomous Manner to Position and Target Retinal Ganglion Cell Axons. J Neurosci 2023; 43:5769-5778. [PMID: 37344233 PMCID: PMC10423046 DOI: 10.1523/jneurosci.0072-22.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/04/2023] [Accepted: 05/01/2023] [Indexed: 06/23/2023] Open
Abstract
Semaphorins and Plexins form ligand/receptor pairs that are crucial for a wide range of developmental processes from cell proliferation to axon guidance. The ability of semaphorins to act both as signaling receptors and ligands yields a multitude of responses. Here, we describe a novel role for Semaphorin-6D (Sema6D) and Plexin-A1 in the positioning and targeting of retinogeniculate axons. In Plexin-A1 or Sema6D mutant mice of either sex, the optic tract courses through, rather than along, the border of the dorsal lateral geniculate nucleus (dLGN), and some retinal axons ectopically arborize adjacent and lateral to the optic tract rather than defasciculating and entering the target region. We find that Sema6D and Plexin-A1 act together in a dose-dependent manner, as the number of the ectopic retinal projections is altered in proportion to the level of Sema6D or Plexin-A1 expression. Moreover, using retinal in utero electroporation of Sema6D or Plexin-A1 shRNA, we show that Sema6D and Plexin-A1 are both required in retinal ganglion cells for axon positioning and targeting. Strikingly, nonelectroporated retinal ganglion cell axons also mistarget in the tract region, indicating that Sema6D and Plexin-A1 can act non-cell-autonomously, potentially through axon-axon interactions. These data provide novel evidence for a dose-dependent and non-cell-autonomous role for Sema6D and Plexin-A1 in retinal axon organization in the optic tract and dLGN.SIGNIFICANCE STATEMENT Before innervating their central brain targets, retinal ganglion cell axons fasciculate in the optic tract and then branch and arborize in their target areas. Upon deletion of the guidance molecules Plexin-A1 or Semaphorin-6D, the optic tract becomes disorganized near and extends within the dorsal lateral geniculate nucleus. In addition, some retinal axons form ectopic aggregates within the defasciculated tract. Sema6D and Plexin-A1 act together as a receptor-ligand pair in a dose-dependent manner, and non-cell-autonomously, to produce this developmental aberration. Such a phenotype highlights an underappreciated role for axon guidance molecules in tract cohesion and appropriate defasciculation near, and arborization within, targets.
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Affiliation(s)
- Delphine S Prieur
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
| | - Cédric Francius
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
| | - Patricia Gaspar
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
| | - Carol A Mason
- Departments of Pathology and Cell Biology, Neuroscience, and Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027
| | - Alexandra Rebsam
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, Paris, 75005, France
- Sorbonne Université, Paris, 75005, France
- Institut du Fer à Moulin, Paris, 75005, France
- Sorbonne Université, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Institut de la Vision, Paris, F-75012, France
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3
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Ehrhardt E, Whitehead SC, Namiki S, Minegishi R, Siwanowicz I, Feng K, Otsuna H, Meissner GW, Stern D, Truman J, Shepherd D, Dickinson MH, Ito K, Dickson BJ, Cohen I, Card GM, Korff W. Single-cell type analysis of wing premotor circuits in the ventral nerve cord of Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.542897. [PMID: 37398009 PMCID: PMC10312520 DOI: 10.1101/2023.05.31.542897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
To perform most behaviors, animals must send commands from higher-order processing centers in the brain to premotor circuits that reside in ganglia distinct from the brain, such as the mammalian spinal cord or insect ventral nerve cord. How these circuits are functionally organized to generate the great diversity of animal behavior remains unclear. An important first step in unraveling the organization of premotor circuits is to identify their constituent cell types and create tools to monitor and manipulate these with high specificity to assess their function. This is possible in the tractable ventral nerve cord of the fly. To generate such a toolkit, we used a combinatorial genetic technique (split-GAL4) to create 195 sparse driver lines targeting 198 individual cell types in the ventral nerve cord. These included wing and haltere motoneurons, modulatory neurons, and interneurons. Using a combination of behavioral, developmental, and anatomical analyses, we systematically characterized the cell types targeted in our collection. Taken together, the resources and results presented here form a powerful toolkit for future investigations of neural circuits and connectivity of premotor circuits while linking them to behavioral outputs.
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Affiliation(s)
- Erica Ehrhardt
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
- Institute of Zoology, University of Cologne, Zülpicher Str 47b, 50674 Cologne, Germany
| | - Samuel C Whitehead
- Physics Department, Cornell University, 271 Clark Hall, Ithaca, New York 14853, USA
| | - Shigehiro Namiki
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Ryo Minegishi
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Igor Siwanowicz
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Kai Feng
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
- Queensland Brain Institute, University of Queensland, 79 Upland Rd, Brisbane, QLD, 4072, Australia
| | - Hideo Otsuna
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - FlyLight Project Team
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Geoffrey W Meissner
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - David Stern
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Jim Truman
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
- Department of Biology, University of Washington, Seattle, Washington 98195, USA
| | - David Shepherd
- School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building, Southampton SO17 1BJ
| | - Michael H. Dickinson
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
- California Institute of Technology, 1200 E California Blvd, Pasadena, California 91125, USA
| | - Kei Ito
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
- Institute of Zoology, University of Cologne, Zülpicher Str 47b, 50674 Cologne, Germany
| | - Barry J Dickson
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Itai Cohen
- Physics Department, Cornell University, 271 Clark Hall, Ithaca, New York 14853, USA
| | - Gwyneth M Card
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
| | - Wyatt Korff
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Dr, Ashburn, Virginia 20147, USA
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Fard D, Testa E, Panzeri V, Rizzolio S, Bianchetti G, Napolitano V, Masciarelli S, Fazi F, Maulucci G, Scicchitano BM, Sette C, Viscomi MT, Tamagnone L. SEMA6C: a novel adhesion-independent FAK and YAP activator, required for cancer cell viability and growth. Cell Mol Life Sci 2023; 80:111. [PMID: 37002363 PMCID: PMC10066115 DOI: 10.1007/s00018-023-04756-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/22/2023] [Accepted: 03/11/2023] [Indexed: 04/03/2023]
Abstract
Transmembrane semaphorins are signaling molecules, controlling axonal wiring and embryo development, which are increasingly implicated in human diseases. Semaphorin 6C (Sema6C) is a poorly understood family member and its functional role is still unclear. Upon targeting Sema6C expression in a range of cancer cells, we observed dramatic growth suppression, decreased ERK phosphorylation, upregulation of cell cycle inhibitor proteins p21, p27 and p53, and the onset of cell senescence, associated with activation of autophagy. These data are consistent with a fundamental requirement for Sema6C to support viability and growth in cancer cells. Mechanistically, we unveiled a novel signaling pathway elicited by Sema6C, and dependent on its intracellular domain, mediated by tyrosine kinases c-Abl and Focal Adhesion Kinase (FAK). Sema6C was found in complex with c-Abl, and induced its phosphorylation, which in turn led to FAK activation, independent of cell-matrix adhesion. Sema6C-induced FAK activity was furthermore responsible for increased nuclear localization of YAP transcriptional regulator. Moreover, Sema6C conferred YAP signaling-dependent long-term cancer cell survival upon nutrient deprivation. In conclusion, our findings demonstrate that Sema6C elicits a cancer promoting-signaling pathway sustaining cell viability and self-renewal, independent of growth factors and nutrients availability.
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Affiliation(s)
- Damon Fard
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Erika Testa
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Valentina Panzeri
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | | | - Giada Bianchetti
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Virginia Napolitano
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Silvia Masciarelli
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
- Department of Anatomical, Histological, Forensic and Orthopaedic Sciences, Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Francesco Fazi
- Department of Anatomical, Histological, Forensic and Orthopaedic Sciences, Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Giuseppe Maulucci
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
- Fondazione Policlinico Gemelli-IRCCS, Rome, Italy
| | - Bianca Maria Scicchitano
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
- Fondazione Policlinico Gemelli-IRCCS, Rome, Italy
| | - Claudio Sette
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
- Fondazione Policlinico Gemelli-IRCCS, Rome, Italy
| | - Maria Teresa Viscomi
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
- Fondazione Policlinico Gemelli-IRCCS, Rome, Italy
| | - Luca Tamagnone
- Department of Life Sciences and Public Health, Università Cattolica del Sacro Cuore, Rome, Italy.
- Fondazione Policlinico Gemelli-IRCCS, Rome, Italy.
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Suzuki M, Nukazuka A, Kamei Y, Yuba S, Oda Y, Takagi S. Mosaic gene expression analysis of semaphorin-plexin interactions in Caenorhabditis elegans using the IR-LEGO single-cell gene induction system. Dev Growth Differ 2022; 64:230-242. [PMID: 35596523 DOI: 10.1111/dgd.12793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 02/17/2022] [Accepted: 03/14/2022] [Indexed: 12/16/2022]
Abstract
Genetic mosaic analysis is a powerful means of addressing the sites of gene action in multicellular organisms. In conventional genetic analysis, the generation of desired mosaic patterns is difficult to control due to the randomness of generating the genetic mosaic which often renders the analysis laborious and time consuming. The infrared laser-evoked gene operator (IR-LEGO) microscope system facilitates genetic mosaic analysis by enabling gene induction in targeted single cells in a living organism. However, the level of gene induction is not controllable due to the usage of a heat-shock promoter. Here, we applied IR-LEGO to examine the cell-cell interactions mediated by semaphoring-plexin signaling in Caenorhabditis elegans by inducing wild-type semaphorin/plexin in single cells within the population of mutant cells lacking the relevant proteins. We found that the cell contact-dependent termination of the extension of vulval precursor cells is elicited by the forward signaling mediated by the semaphorin receptor, PLX-1, but not by the reverse signaling via the transmembrane semaphorin, SMP-1. By utilizing Cre/loxP recombination coupled with the IR-LEGO system to induce SMP-1 at a physiological level, we found that SMP-1 interacts with PLX-1 only in trans upon contact between vulval precursor cells. In contrast, when overexpressed, SMP-1 exhibits the ability to cis-interact with PLX-1 on a single cell. These results indicate that mosaic analysis with IR-LEGO, especially when combined with an in vivo recombination system, efficiently complements conventional methods.
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Affiliation(s)
- Motoshi Suzuki
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Akira Nukazuka
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Yasuhiro Kamei
- Laboratory for Biothermology, National Institute of Basic Biology, Okazaki, Aichi, Japan
| | - Shunsuke Yuba
- Research Institute for Cell Engineering, National Institute of Advanced and Industrial Science and Technology, Ikeda, Osaka, Japan
| | - Yoichi Oda
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Shin Takagi
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
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Semaphorin 1a-mediated dendritic wiring of the Drosophila mushroom body extrinsic neurons. Proc Natl Acad Sci U S A 2022; 119:e2111283119. [PMID: 35286204 PMCID: PMC8944846 DOI: 10.1073/pnas.2111283119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The adult Drosophila mushroom body (MB) is one of the most extensively studied neural circuits. However, how its circuit organization is established during development is unclear. In this study, we provide an initial characterization of the assembly process of the extrinsic neurons (dopaminergic neurons and MB output neurons) that target the vertical MB lobes. We probe the cellular mechanisms guiding the neurite targeting of these extrinsic neurons and demonstrate that Semaphorin 1a is required in several MB output neurons for their dendritic innervations to three specific MB lobe zones. Our study reveals several intriguing molecular and cellular principles governing assembly of the MB circuit. The Drosophila mushroom body (MB) is composed of parallel axonal fibers from intrinsic Kenyon cells (KCs). The parallel fibers are bundled into five MB lobes innervated by extrinsic neurons, including dopaminergic neurons (DANs) and MB output neurons (MBONs) that project axons or dendrites to the MB lobes, respectively. Each DAN and MBON innervates specific regions in the lobes and collectively subdivides them into 15 zones. How such modular circuit architecture is established remains unknown. Here, we followed the development of the DANs and MBONs targeting the vertical lobes of the adult MB. We found that these extrinsic neurons innervate the lobes sequentially and their neurite arborizations in the MB lobe zones are independent of each other. Ablation of DAN axons or MBON dendrites in a zone had a minimal effect on other extrinsic neurites in the same or neighboring zones, suggesting that these neurons do not use tiling mechanisms to establish zonal borders. In contrast, KC axons are necessary for the development of extrinsic neurites. Dendrites of some vertical lobe-innervating MBONs were redirected to specific zones in the horizontal lobes when their normal target lobes were missing, indicating a hierarchical organization of guidance signals for the MBON dendrites. We show that Semaphorin 1a is required in MBONs to innervate three specific MB zones, and overexpression of semaphorin 1a is sufficient to redirect DAN dendrites to these zones. Our study provides an initial characterization of the cellular and molecular mechanisms underlying the assembly process of MB extrinsic neurons.
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Carulli D, de Winter F, Verhaagen J. Semaphorins in Adult Nervous System Plasticity and Disease. Front Synaptic Neurosci 2021; 13:672891. [PMID: 34045951 PMCID: PMC8148045 DOI: 10.3389/fnsyn.2021.672891] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/12/2021] [Indexed: 12/13/2022] Open
Abstract
Semaphorins, originally discovered as guidance cues for developing axons, are involved in many processes that shape the nervous system during development, from neuronal proliferation and migration to neuritogenesis and synapse formation. Interestingly, the expression of many Semaphorins persists after development. For instance, Semaphorin 3A is a component of perineuronal nets, the extracellular matrix structures enwrapping certain types of neurons in the adult CNS, which contribute to the closure of the critical period for plasticity. Semaphorin 3G and 4C play a crucial role in the control of adult hippocampal connectivity and memory processes, and Semaphorin 5A and 7A regulate adult neurogenesis. This evidence points to a role of Semaphorins in the regulation of adult neuronal plasticity. In this review, we address the distribution of Semaphorins in the adult nervous system and we discuss their function in physiological and pathological processes.
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Affiliation(s)
- Daniela Carulli
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
- Department of Neuroscience Rita Levi-Montalcini and Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
| | - Fred de Winter
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
| | - Joost Verhaagen
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, Amsterdam, Netherlands
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Furusawa K, Emoto K. Scrap and Build for Functional Neural Circuits: Spatiotemporal Regulation of Dendrite Degeneration and Regeneration in Neural Development and Disease. Front Cell Neurosci 2021; 14:613320. [PMID: 33505249 PMCID: PMC7829185 DOI: 10.3389/fncel.2020.613320] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/04/2020] [Indexed: 01/01/2023] Open
Abstract
Dendrites are cellular structures essential for the integration of neuronal information. These elegant but complex structures are highly patterned across the nervous system but vary tremendously in their size and fine architecture, each designed to best serve specific computations within their networks. Recent in vivo imaging studies reveal that the development of mature dendrite arbors in many cases involves extensive remodeling achieved through a precisely orchestrated interplay of growth, degeneration, and regeneration of dendritic branches. Both degeneration and regeneration of dendritic branches involve precise spatiotemporal regulation for the proper wiring of functional networks. In particular, dendrite degeneration must be targeted in a compartmentalized manner to avoid neuronal death. Dysregulation of these developmental processes, in particular dendrite degeneration, is associated with certain types of pathology, injury, and aging. In this article, we review recent progress in our understanding of dendrite degeneration and regeneration, focusing on molecular and cellular mechanisms underlying spatiotemporal control of dendrite remodeling in neural development. We further discuss how developmental dendrite degeneration and regeneration are molecularly and functionally related to dendrite remodeling in pathology, disease, and aging.
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Affiliation(s)
- Kotaro Furusawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Kazuo Emoto
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Tokyo, Japan
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9
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Clements J, Buhler K, Winant M, Vulsteke V, Callaerts P. Glial and Neuronal Neuroglian, Semaphorin-1a and Plexin A Regulate Morphological and Functional Differentiation of Drosophila Insulin-Producing Cells. Front Endocrinol (Lausanne) 2021; 12:600251. [PMID: 34276554 PMCID: PMC8281472 DOI: 10.3389/fendo.2021.600251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 06/11/2021] [Indexed: 11/21/2022] Open
Abstract
The insulin-producing cells (IPCs), a group of 14 neurons in the Drosophila brain, regulate numerous processes, including energy homeostasis, lifespan, stress response, fecundity, and various behaviors, such as foraging and sleep. Despite their importance, little is known about the development and the factors that regulate morphological and functional differentiation of IPCs. In this study, we describe the use of a new transgenic reporter to characterize the role of the Drosophila L1-CAM homolog Neuroglian (Nrg), and the transmembrane Semaphorin-1a (Sema-1a) and its receptor Plexin A (PlexA) in the differentiation of the insulin-producing neurons. Loss of Nrg results in defasciculation and abnormal neurite branching, including ectopic neurites in the IPC neurons. Cell-type specific RNAi knockdown experiments reveal that Nrg, Sema-1a and PlexA are required in IPCs and glia to control normal morphological differentiation of IPCs albeit with a stronger contribution of Nrg and Sema-1a in glia and of PlexA in the IPCs. These observations provide new insights into the development of the IPC neurons and identify a novel role for Sema-1a in glia. In addition, we show that Nrg, Sema-1a and PlexA in glia and IPCs not only regulate morphological but also functional differentiation of the IPCs and that the functional deficits are likely independent of the morphological phenotypes. The requirements of nrg, Sema-1a, and PlexA in IPC development and the expression of their vertebrate counterparts in the hypothalamic-pituitary axis, suggest that these functions may be evolutionarily conserved in the establishment of vertebrate endocrine systems.
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Cheong HSJ, Nona M, Guerra SB, VanBerkum MF. The first quarter of the C-terminal domain of Abelson regulates the WAVE regulatory complex and Enabled in axon guidance. Neural Dev 2020; 15:7. [PMID: 32359359 PMCID: PMC7196227 DOI: 10.1186/s13064-020-00144-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/17/2020] [Indexed: 12/16/2022] Open
Abstract
Background Abelson tyrosine kinase (Abl) plays a key role in axon guidance in linking guidance receptors to actin dynamics. The long C-terminal domain (CTD) of Drosophila Abl is important for this role, and previous work identified the ‘first quarter’ (1Q) of the CTD as essential. Here, we link the physical interactions of 1Q binding partners to Abl’s function in axon guidance. Methods Protein binding partners of 1Q were identified by GST pulldown and mass spectrometry, and validated using axon guidance assays in the embryonic nerve cord and motoneurons. The role of 1Q was assessed genetically, utilizing a battery of Abl transgenes in combination with mutation or overexpression of the genes of pulled down proteins, and their partners in actin dynamics. The set of Abl transgenes had the following regions deleted: all of 1Q, each half of 1Q (‘eighths’, 1E and 2E) or a PxxP motif in 2E, which may bind SH3 domains. Results GST pulldown identified Hem and Sra-1 as binding partners of 1Q, and our genetic analyses show that both proteins function with Abl in axon guidance, with Sra-1 likely interacting with 1Q. As Hem and Sra-1 are part of the actin-polymerizing WAVE regulatory complex (WRC), we extended our analyses to Abi and Trio, which interact with Abl and WRC members. Overall, the 1Q region (and especially 2E and its PxxP motif) are important for Abl’s ability to work with WRC in axon guidance. These areas are also important for Abl’s ability to function with the actin regulator Enabled. In comparison, 1E contributes to Abl function with the WRC at the midline, but less so with Enabled. Conclusions The 1Q region, and especially the 2E region with its PxxP motif, links Abl with the WRC, its regulators Trio and Abi, and the actin regulator Ena. Removing 1E has specific effects suggesting it may help modulate Abl’s interaction with the WRC or Ena. Thus, the 1Q region of Abl plays a key role in regulating actin dynamics during axon guidance.
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Affiliation(s)
| | - Mark Nona
- Department of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA
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11
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De Novo Truncating Variants in the Last Exon of SEMA6B Cause Progressive Myoclonic Epilepsy. Am J Hum Genet 2020; 106:549-558. [PMID: 32169168 DOI: 10.1016/j.ajhg.2020.02.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/19/2020] [Indexed: 12/22/2022] Open
Abstract
De novo variants (DNVs) cause many genetic diseases. When DNVs are examined in the whole coding regions of genes in next-generation sequencing analyses, pathogenic DNVs often cluster in a specific region. One such region is the last exon and the last 50 bp of the penultimate exon, where truncating DNVs cause escape from nonsense-mediated mRNA decay [NMD(-) region]. Such variants can have dominant-negative or gain-of-function effects. Here, we first developed a resource of rates of truncating DNVs in NMD(-) regions under the null model of DNVs. Utilizing this resource, we performed enrichment analysis of truncating DNVs in NMD(-) regions in 346 developmental and epileptic encephalopathy (DEE) trios. We observed statistically significant enrichment of truncating DNVs in semaphorin 6B (SEMA6B) (p value: 2.8 × 10-8; exome-wide threshold: 2.5 × 10-6). The initial analysis of the 346 individuals and additional screening of 1,406 and 4,293 independent individuals affected by DEE and developmental disorders collectively identified four truncating DNVs in the SEMA6B NMD(-) region in five individuals who came from unrelated families (p value: 1.9 × 10-13) and consistently showed progressive myoclonic epilepsy. RNA analysis of lymphoblastoid cells established from an affected individual showed that the mutant allele escaped NMD, indicating stable production of the truncated protein. Importantly, heterozygous truncating variants in the NMD(+) region of SEMA6B are observed in general populations, and SEMA6B is most likely loss-of-function tolerant. Zebrafish expressing truncating variants in the NMD(-) region of SEMA6B orthologs displayed defective development of brain neurons and enhanced pentylenetetrazole-induced seizure behavior. In summary, we show that truncating DNVs in the final exon of SEMA6B cause progressive myoclonic epilepsy.
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Hong YG, Kang B, Lee S, Lee Y, Ju BG, Jeong S. Identification of cis -Regulatory Region Controlling Semaphorin-1a Expression in the Drosophila Embryonic Nervous System. Mol Cells 2020; 43:228-235. [PMID: 32024353 PMCID: PMC7103886 DOI: 10.14348/molcells.2019.0294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 11/27/2022] Open
Abstract
The Drosophila transmembrane semaphorin Sema-1a mediates forward and reverse signaling that plays an essential role in motor and central nervous system (CNS) axon pathfinding during embryonic neural development. Previous immunohistochemical analysis revealed that Sema-1a is expressed on most commissural and longitudinal axons in the CNS and five motor nerve branches in the peripheral nervous system (PNS). However, Sema-1a-mediated axon guidance function contributes significantly to both intersegmental nerve b (ISNb) and segmental nerve a (SNa), and slightly to ISNd and SNc, but not to ISN motor axon pathfinding. Here, we uncover three cis-regulatory elements (CREs), R34A03, R32H10, and R33F06, that robustly drove reporter expression in a large subset of neurons in the CNS. In the transgenic lines R34A03 and R32H10 reporter expression was consistently observed on both ISNb and SNa nerve branches, whereas in the line R33F06 reporter expression was irregularly detected on ISNb or SNa nerve branches in small subsets of abdominal hemisegments. Through complementation test with a Sema1a loss-of-function allele, we found that neuronal expression of Sema-1a driven by each of R34A03 and R32H10 restores robustly the CNS and PNS motor axon guidance defects observed in Sema-1a homozygous mutants. However, when wild-type Sema-1a is expressed by R33F06 in Sema-1a mutants, the Sema-1a PNS axon guidance phenotypes are partially rescued while the Sema-1a CNS axon guidance defects are completely rescued. These results suggest that in a redundant manner, the CREs, R34A03, R32H10, and R33F06 govern the Sema-1a expression required for the axon guidance function of Sema-1a during embryonic neural development.
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Affiliation(s)
- Young Gi Hong
- Division of Life Sciences (Molecular Biology Major), Jeonbuk National University, Jeonju 54896, Korea
| | - Bongsu Kang
- Division of Life Sciences (Molecular Biology Major), Jeonbuk National University, Jeonju 54896, Korea
- Department of Bioactive Material Sciences and Research Center of Bioactive Materials, Jeonbuk National University, Jeonju 54896, Korea
| | - Seongsoo Lee
- Gwangju Center, Korea Basic Science Institute, Gwangju 61186, Korea
| | - Youngseok Lee
- Department of Bio and Fermentation Convergence Technology, BK21 PLUS Project, Kookmin University, Seoul 02707, Korea
| | - Bong-Gun Ju
- Department of Life Science, Sogang University, Seoul 04107, Korea
| | - Sangyun Jeong
- Division of Life Sciences (Molecular Biology Major), Jeonbuk National University, Jeonju 54896, Korea
- Department of Bioactive Material Sciences and Research Center of Bioactive Materials, Jeonbuk National University, Jeonju 54896, Korea
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Ko PH, Lenka G, Chen YA, Chuang EY, Tsai MH, Sher YP, Lai LC. Semaphorin 5A suppresses the proliferation and migration of lung adenocarcinoma cells. Int J Oncol 2019; 56:165-177. [PMID: 31789397 PMCID: PMC6910195 DOI: 10.3892/ijo.2019.4932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 11/13/2019] [Indexed: 12/26/2022] Open
Abstract
Semaphorin 5A (SEMA5A), a member of the semaphorin family, plays an important role in axonal guidance. Previously, the authors identified another possible role of SEMA5A as a prognostic biomarker for non-smoking women with lung adenocarcinoma in Taiwan, and this phenomenon has been validated in other ethnic groups. However, the functional significance of SEMA5A in lung adenocarcinoma remains unclear. Therefore, we assessed the function of SEMA5A in three lung adenocarcinoma cell lines in this study. Kaplan-Meier Plotter for lung cancer was conducted for survival analyses. Reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis were performed to investigate the expression and post-translational regulation of SEMA5A in lung adenocar-cinoma cell lines. A pre-designed PyroMark CpG assay and 5-aza-2′-deoxycytidine treatment were used to measure the methylation levels of SEMA5A. The biological functions of lung adenocarcinoma cells overexpressing SEMA5A were investigated by microarrays, and validated both in vitro (proliferation, colony formation and migration assays) and in vivo (tumor xenografts) experiments. The results revealed that the hypermethylation of SEMA5A and the cleavage of the extracellular domain of SEMA5A were responsible for the downregulation of the SEMA5A levels in lung adenocarcinoma cells (A549 and H1299) as compared to the normal controls. Functional analysis of SEMA5A-regulated genes revealed that they were involved in cellular growth and proliferation. The overexpression of SEMA5A in A549 and H1299 cells significantly decreased the proliferation (P<0.01), colony formation (P<0.001) and migratory ability (P<0.01) of the cells. The suppressive effects of SEMA5A on the proliferative and migratory ability of the cells were also observed in both in vitro and in vivo experiments using brain metastatic Bm7 lung adenocarcinoma cells. On the whole, the findings of this study suggest a suppressive role for SEMA5A in lung adenocarcinoma involving the inhibition of the proliferation and migration of lung transformed cells.
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Affiliation(s)
- Pin-Hao Ko
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 10051, Taiwan, R.O.C
| | - Govinda Lenka
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 10051, Taiwan, R.O.C
| | - Yu-An Chen
- Bioinformatics and Biostatistics Core, Center of Genomic and Precision Medicine, National Taiwan University, Taipei 10055, Taiwan, R.O.C
| | - Eric Y Chuang
- Bioinformatics and Biostatistics Core, Center of Genomic and Precision Medicine, National Taiwan University, Taipei 10055, Taiwan, R.O.C
| | - Mong-Hsun Tsai
- Bioinformatics and Biostatistics Core, Center of Genomic and Precision Medicine, National Taiwan University, Taipei 10055, Taiwan, R.O.C
| | - Yuh-Pyng Sher
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung 40402, Taiwan, R.O.C
| | - Liang-Chuan Lai
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 10051, Taiwan, R.O.C
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Horch HW, Spicer SB, Low IIC, Joncas CT, Quenzer ED, Okoya H, Ledwidge LM, Fisher HP. Characterization of plexinA and two distinct semaphorin1a transcripts in the developing and adult cricket Gryllus bimaculatus. J Comp Neurol 2019; 528:687-702. [PMID: 31621906 DOI: 10.1002/cne.24790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/26/2019] [Accepted: 09/26/2019] [Indexed: 11/06/2022]
Abstract
Guidance cues act during development to guide growth cones to their proper targets in both the central and peripheral nervous systems. Experiments in many species indicate that guidance molecules also play important roles after development, though less is understood about their functions in the adult. The Semaphorin family of guidance cues, signaling through Plexin receptors, influences the development of both axons and dendrites in invertebrates. Semaphorin functions have been extensively explored in Drosophila melanogaster and some other Dipteran species, but little is known about their function in hemimetabolous insects. Here, we characterize sema1a and plexA in the cricket Gryllus bimaculatus. In fact, we found two distinct predicted Sema1a proteins in this species, Sema1a.1 and Sema1a.2, which shared only 48% identity at the amino acid level. We include a phylogenetic analysis that predicted that many other insect species, both holometabolous and hemimetabolous, express two Sema1a proteins as well. Finally, we used in situ hybridization to show that sema1a.1 and sema1a.2 expression patterns were spatially distinct in the embryo, and both roughly overlap with plexA. All three transcripts were also expressed in the adult brain, mainly in the mushroom bodies, though sema1a.2 was expressed most robustly. sema1a.2 was also expressed strongly in the adult thoracic ganglia while sema1a.1 was only weakly expressed and plexA was undetectable.
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Affiliation(s)
- Hadley W Horch
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Sara B Spicer
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Isabel I C Low
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Colby T Joncas
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Eleanor D Quenzer
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Hikmah Okoya
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Lisa M Ledwidge
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
| | - Harrison P Fisher
- Department of Biology and Neuroscience, Bowdoin College, Brunswick, Maine
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15
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Rozbesky D, Robinson RA, Jain V, Renner M, Malinauskas T, Harlos K, Siebold C, Jones EY. Diversity of oligomerization in Drosophila semaphorins suggests a mechanism of functional fine-tuning. Nat Commun 2019; 10:3691. [PMID: 31417095 PMCID: PMC6695400 DOI: 10.1038/s41467-019-11683-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 07/30/2019] [Indexed: 12/30/2022] Open
Abstract
Semaphorin ligands and their plexin receptors are one of the major cell guidance factors that trigger localised changes in the cytoskeleton. Binding of semaphorin homodimer to plexin brings two plexins in close proximity which is a prerequisite for plexin signalling. This model appears to be too simplistic to explain the complexity and functional versatility of these molecules. Here, we determine crystal structures for all members of Drosophila class 1 and 2 semaphorins. Unlike previously reported semaphorin structures, Sema1a, Sema2a and Sema2b show stabilisation of sema domain dimer formation via a disulfide bond. Unexpectedly, our structural and biophysical data show Sema1b is a monomer suggesting that semaphorin function may not be restricted to dimers. We demonstrate that semaphorins can form heterodimers with members of the same semaphorin class. This heterodimerization provides a potential mechanism for cross-talk between different plexins and co-receptors to allow fine-tuning of cell signalling.
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Affiliation(s)
- Daniel Rozbesky
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK.
| | - Ross A Robinson
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
- Immunocore Ltd, Milton Park, Abingdon, OX14 4RY, UK
| | - Vitul Jain
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Max Renner
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Karl Harlos
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK.
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16
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Sales EC, Heckman EL, Warren TL, Doe CQ. Regulation of subcellular dendritic synapse specificity by axon guidance cues. eLife 2019; 8:43478. [PMID: 31012844 PMCID: PMC6499537 DOI: 10.7554/elife.43478] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 04/18/2019] [Indexed: 11/13/2022] Open
Abstract
Neural circuit assembly occurs with subcellular precision, yet the mechanisms underlying this precision remain largely unknown. Subcellular synaptic specificity could be achieved by molecularly distinct subcellular domains that locally regulate synapse formation, or by axon guidance cues restricting access to one of several acceptable targets. We address these models using two Drosophila neurons: the dbd sensory neuron and the A08a interneuron. In wild-type larvae, dbd synapses with the A08a medial dendrite but not the A08a lateral dendrite. dbd-specific overexpression of the guidance receptors Unc-5 or Robo-2 results in lateralization of the dbd axon, which forms anatomical and functional monosynaptic connections with the A08a lateral dendrite. We conclude that axon guidance cues, not molecularly distinct dendritic arbors, are a major determinant of dbd-A08a subcellular synapse specificity.
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Affiliation(s)
- Emily C Sales
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Emily L Heckman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Timothy L Warren
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, United States.,Institute of Molecular Biology, Howard Hughes Medical Institute, University of Oregon, Eugene, United States
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17
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A Computational Model of the Escape Response Latency in the Giant Fiber System of Drosophila melanogaster. eNeuro 2019; 6:eN-NWR-0423-18. [PMID: 31001574 PMCID: PMC6469880 DOI: 10.1523/eneuro.0423-18.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/22/2019] [Accepted: 03/11/2019] [Indexed: 11/29/2022] Open
Abstract
The giant fiber system (GFS) is a multi-component neuronal pathway mediating rapid escape response in the adult fruit-fly Drosophila melanogaster, usually in the face of a threatening visual stimulus. Two branches of the circuit promote the response by stimulating an escape jump followed by flight initiation. A recent work demonstrated an age-associated decline in the speed of signal propagation through the circuit, measured as the stimulus-to-muscle depolarization response latency. The decline is likely due to the diminishing number of inter-neuronal gap junctions in the GFS of ageing flies. In this work, we presented a realistic conductance-based, computational model of the GFS that recapitulates the experimental results and identifies some of the critical anatomical and physiological components governing the circuit’s response latency. According to our model, anatomical properties of the GFS neurons have a stronger impact on the transmission than neuronal membrane conductance densities. The model provides testable predictions for the effect of experimental interventions on the circuit’s performance in young and ageing flies.
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18
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Kennedy T, Broadie K. Newly Identified Electrically Coupled Neurons Support Development of the Drosophila Giant Fiber Model Circuit. eNeuro 2018; 5:ENEURO.0346-18.2018. [PMID: 30627638 PMCID: PMC6325540 DOI: 10.1523/eneuro.0346-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/29/2018] [Accepted: 11/12/2018] [Indexed: 12/31/2022] Open
Abstract
The Drosophila giant fiber (GF) escape circuit is an extensively studied model for neuron connectivity and function. Researchers have long taken advantage of the simple linear neuronal pathway, which begins at peripheral sensory modalities, travels through the central GF interneuron (GFI) to motor neurons, and terminates on wing/leg muscles. This circuit is more complex than it seems, however, as there exists a complex web of coupled neurons connected to the GFI that widely innervates the thoracic ganglion. Here, we define four new neuron clusters dye coupled to the central GFI, which we name GF coupled (GFC) 1-4. We identify new transgenic Gal4 drivers that express specifically in these neurons, and map both neuronal architecture and synaptic polarity. GFC1-4 share a central site of GFI connectivity, the inframedial bridge, where the neurons each form electrical synapses. Targeted apoptotic ablation of GFC1 reveals a key role for the proper development of the GF circuit, including the maintenance of GFI connectivity with upstream and downstream synaptic partners. GFC1 ablation frequently results in the loss of one GFI, which is always compensated for by contralateral innervation from a branch of the persisting GFI axon. Overall, this work reveals extensively coupled interconnectivity within the GF circuit, and the requirement of coupled neurons for circuit development. Identification of this large population of electrically coupled neurons in this classic model, and the ability to genetically manipulate these electrically synapsed neurons, expands the GF system capabilities for the nuanced, sophisticated circuit dissection necessary for deeper investigations into brain formation.
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Affiliation(s)
- Tyler Kennedy
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Department of Cell and Developmental Biology, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
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19
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Bai Z, Li Z, Xiao W. Drosophila bendless catalyzes K63-linked polyubiquitination and is involved in the response to DNA damage. Mutat Res 2018. [PMID: 29518634 DOI: 10.1016/j.mrfmmm.2018.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In this study, we report the identification and functional characterization of the Drosophila ben/ubc13 gene, encoding a unique ubiquitin-conjugating enzyme (Ubc or E2), in DNA-damage response. Ben forms a heterodimer with DmUev1a, the only Ubc/E2 variant (Uev) in Drosophila. Ben and DmUev1a act together to catalyze K63-linked polyubiquitination in vitro. ben can functionally rescue the yeast ubc13 null mutant from killing by DNA-damaging agents. We also find that BenP97S, which was previously described to affect the connectivity between the giant fiber and the tergotrochanter motor neuron, fails to interact with the RING protein Chfr but retains interaction with DmUev1a as well as Uevs from other species. The corresponding yeast Ubc13P97S interacts with Mms2 but fails to bind Rad5. Consequently, neither benP97S nor ubc13P97S is able to complement the yeast ubc13 mutant defective in error-free DNA-damage tolerance. More importantly, the benP97S mutant flies are more sensitive to a DNA-damaging agent, suggesting that Ben functions in a manner similar to its yeast and mammalian counterparts. Collectively, our observations imply that Ben-DmUev1a-promoted K63-linked polyubiquitination and involvement in DNA-damage response are highly conserved in eukaryotes including flies.
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Affiliation(s)
- Zhiqiang Bai
- Beijing Key Laboratory of DNA Damage Responses and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhouhua Li
- Beijing Key Laboratory of DNA Damage Responses and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Wei Xiao
- Beijing Key Laboratory of DNA Damage Responses and College of Life Sciences, Capital Normal University, Beijing 100048, China; Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
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20
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Hernandez-Fleming M, Rohrbach EW, Bashaw GJ. Sema-1a Reverse Signaling Promotes Midline Crossing in Response to Secreted Semaphorins. Cell Rep 2017; 18:174-184. [PMID: 28052247 DOI: 10.1016/j.celrep.2016.12.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/21/2016] [Accepted: 12/08/2016] [Indexed: 11/26/2022] Open
Abstract
Commissural axons must cross the midline to form functional midline circuits. In the invertebrate nerve cord and vertebrate spinal cord, midline crossing is mediated in part by Netrin-dependent chemoattraction. Loss of crossing, however, is incomplete in mutants for Netrin or its receptor Frazzled/DCC, suggesting the existence of additional pathways. We identified the transmembrane Semaphorin, Sema-1a, as an important regulator of midline crossing in the Drosophila CNS. We show that in response to the secreted Semaphorins Sema-2a and Sema-2b, Sema-1a functions as a receptor to promote crossing independently of Netrin. In contrast to other examples of reverse signaling where Sema1a triggers repulsion through activation of Rho in response to Plexin binding, in commissural neurons Sema-1a acts independently of Plexins to inhibit Rho to promote attraction to the midline. These findings suggest that Sema-1a reverse signaling can elicit distinct axonal responses depending on differential engagement of distinct ligands and signaling effectors.
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Affiliation(s)
- Melissa Hernandez-Fleming
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Ethan W Rohrbach
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Greg J Bashaw
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, 415 Curie Boulevard, Philadelphia, PA 19104, USA.
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21
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Kennedy T, Broadie K. Fragile X Mental Retardation Protein Restricts Small Dye Iontophoresis Entry into Central Neurons. J Neurosci 2017; 37:9844-9858. [PMID: 28887386 PMCID: PMC5637114 DOI: 10.1523/jneurosci.0723-17.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 07/27/2017] [Accepted: 08/29/2017] [Indexed: 01/29/2023] Open
Abstract
Fragile X mental retardation protein (FMRP) loss causes Fragile X syndrome (FXS), a major disorder characterized by autism, intellectual disability, hyperactivity, and seizures. FMRP is both an RNA- and channel-binding regulator, with critical roles in neural circuit formation and function. However, it remains unclear how these FMRP activities relate to each other and how dysfunction in their absence underlies FXS neurological symptoms. In testing circuit level defects in the Drosophila FXS model, we discovered a completely unexpected and highly robust neuronal dye iontophoresis phenotype in the well mapped giant fiber (GF) circuit. Controlled dye injection into the GF interneuron results in a dramatic increase in dye uptake in neurons lacking FMRP. Transgenic wild-type FMRP reintroduction rescues the mutant defect, demonstrating a specific FMRP requirement. This phenotype affects only small dyes, but is independent of dye charge polarity. Surprisingly, the elevated dye iontophoresis persists in shaking B mutants that eliminate gap junctions and dye coupling among GF circuit neurons. We therefore used a wide range of manipulations to investigate the dye uptake defect, including timed injection series, pharmacology and ion replacement, and optogenetic activity studies. The results show that FMRP strongly limits the rate of dye entry via a cytosolic mechanism. This study reveals an unexpected new phenotype in a physical property of central neurons lacking FMRP that could underlie aspects of FXS disruption of neural function.SIGNIFICANCE STATEMENT FXS is a leading heritable cause of intellectual disability and autism spectrum disorders. Although researchers established the causal link with FMRP loss >;25 years ago, studies continue to reveal diverse FMRP functions. The Drosophila FXS model is key to discovering new FMRP roles, because of its genetic malleability and individually identified neuron maps. Taking advantage of a well characterized Drosophila neural circuit, we discovered that neurons lacking FMRP take up dramatically more current-injected small dye. After examining many neuronal properties, we determined that this dye defect is cytoplasmic and occurs due to a highly elevated dye iontophoresis rate. We also report several new factors affecting neuron dye uptake. Understanding how FMRP regulates iontophoresis should reveal new molecular factors underpinning FXS dysfunction.
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Affiliation(s)
| | - Kendal Broadie
- Department of Biological Sciences,
- Department of Cell and Developmental Biology, and
- Vanderbilt Brain Institute, Vanderbilt University and Medical Center, Nashville, Tennessee 37235
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22
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Varicose and cheerio collaborate with pebble to mediate semaphorin-1a reverse signaling in Drosophila. Proc Natl Acad Sci U S A 2017; 114:E8254-E8263. [PMID: 28894005 DOI: 10.1073/pnas.1713010114] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transmembrane semaphorin Sema-1a acts as both a ligand and a receptor to regulate axon-axon repulsion during neural development. Pebble (Pbl), a Rho guanine nucleotide exchange factor, mediates Sema-1a reverse signaling through association with the N-terminal region of the Sema-1a intracellular domain (ICD), resulting in cytoskeletal reorganization. Here, we uncover two additional Sema-1a interacting proteins, varicose (Vari) and cheerio (Cher), each with neuronal functions required for motor axon pathfinding. Vari is a member of the membrane-associated guanylate kinase (MAGUK) family of proteins, members of which can serve as scaffolds to organize signaling complexes. Cher is related to actin filament cross-linking proteins that regulate actin cytoskeleton dynamics. The PDZ domain binding motif found in the most C-terminal region of the Sema-1a ICD is necessary for interaction with Vari, but not Cher, indicative of distinct binding modalities. Pbl/Sema-1a-mediated repulsive guidance is potentiated by both vari and cher Genetic analyses further suggest that scaffolding functions of Vari and Cher play an important role in Pbl-mediated Sema-1a reverse signaling. These results define intracellular components critical for signal transduction from the Sema-1a receptor to the cytoskeleton and provide insight into mechanisms underlying semaphorin-induced localized changes in cytoskeletal organization.
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23
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Kudumala SR, Penserga T, Börner J, Slipchuk O, Kakad P, Lee LH, Qureshi A, Pielage J, Godenschwege TA. Lissencephaly-1 dependent axonal retrograde transport of L1-type CAM Neuroglian in the adult drosophila central nervous system. PLoS One 2017; 12:e0183605. [PMID: 28837701 PMCID: PMC5570280 DOI: 10.1371/journal.pone.0183605] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 08/08/2017] [Indexed: 11/25/2022] Open
Abstract
Here, we established the Drosophila Giant Fiber neurons (GF) as a novel model to study axonal trafficking of L1-type Cell Adhesion Molecules (CAM) Neuroglian (Nrg) in the adult CNS using live imaging. L1-type CAMs are well known for their importance in nervous system development and we previously demonstrated a role for Nrg in GF synapse formation. However, in the adult they have also been implicated in synaptic plasticity and regeneration. In addition, to its canonical role in organizing cytoskeletal elements at the plasma membrane, vertebrate L1CAM has also been shown to regulate transcription indirectly as well as directly via its import to the nucleus. Here, we intend to determine if the sole L1CAM homolog Nrg is retrogradley transported and thus has the potential to relay signals from the synapse to the soma. Live imaging of c-terminally tagged Nrg in the GF revealed that there are at least two populations of retrograde vesicles that differ in speed, and either move with consistent or varying velocity. To determine if endogenous Nrg is retrogradely transported, we inhibited two key regulators, Lissencephaly-1 (Lis1) and Dynactin, of the retrograde motor protein Dynein. Similar to previously described phenotypes for expression of poisonous subunits of Dynactin, we found that developmental knock down of Lis1 disrupted GF synaptic terminal growth and that Nrg vesicles accumulated inside the stunted terminals in both mutant backgrounds. Moreover, post mitotic Lis1 knock down in mature GFs by either RNAi or Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) induced mutations, resulted in normal length terminals with fully functional GF synapses which also exhibited severe accumulation of endogenous Nrg vesicles. Thus, our data suggests that accumulation of Nrg vesicles is due to failure of retrograde transport rather than a failure of terminal development. Together with the finding that post mitotic knock down of Lis1 also disrupted retrograde transport of tagged Nrg vesicles in GF axons, it demonstrates that endogenous Nrg protein is transported from the synapse to the soma in the adult central nervous system in a Lis1-dependent manner.
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Affiliation(s)
- Sirisha R. Kudumala
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Tyrone Penserga
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Jana Börner
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Olesya Slipchuk
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Priyanka Kakad
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - LaTasha H. Lee
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Aater Qureshi
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, Florida, United States of America
| | - Jan Pielage
- Department of Biology, Division of Zoology/Neurobiology, Technische Universität Kaiserslautern, Kaiserslautern, Germany
| | - Tanja A. Godenschwege
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, United States of America
- * E-mail:
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24
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Sun T, Yang L, Kaur H, Pestel J, Looso M, Nolte H, Krasel C, Heil D, Krishnan RK, Santoni MJ, Borg JP, Bünemann M, Offermanns S, Swiercz JM, Worzfeld T. A reverse signaling pathway downstream of Sema4A controls cell migration via Scrib. J Cell Biol 2016; 216:199-215. [PMID: 28007914 PMCID: PMC5223600 DOI: 10.1083/jcb.201602002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 09/30/2016] [Accepted: 11/13/2016] [Indexed: 11/22/2022] Open
Abstract
Semaphorins comprise a large family of ligands that regulate key cellular functions through their receptors, plexins. In this study, we show that the transmembrane semaphorin 4A (Sema4A) can also function as a receptor, rather than a ligand, and transduce signals triggered by the binding of Plexin-B1 through reverse signaling. Functionally, reverse Sema4A signaling regulates the migration of various cancer cells as well as dendritic cells. By combining mass spectrometry analysis with small interfering RNA screening, we identify the polarity protein Scrib as a downstream effector of Sema4A. We further show that binding of Plexin-B1 to Sema4A promotes the interaction of Sema4A with Scrib, thereby removing Scrib from its complex with the Rac/Cdc42 exchange factor βPIX and decreasing the activity of the small guanosine triphosphatase Rac1 and Cdc42. Our data unravel a role for Plexin-B1 as a ligand and Sema4A as a receptor and characterize a reverse signaling pathway downstream of Sema4A, which controls cell migration.
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Affiliation(s)
- Tianliang Sun
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Lida Yang
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Harmandeep Kaur
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Jenny Pestel
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Mario Looso
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Hendrik Nolte
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Cornelius Krasel
- Institute of Pharmacology and Clinical Pharmacy, Biochemical-Pharmacological Center, University of Marburg, 35043 Marburg, Germany
| | - Daniel Heil
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Ramesh K Krishnan
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Marie-Josée Santoni
- Cell Polarity, Cell Signaling and Cancer, Equipe labellisée Ligue Contre le Cancer, Institut National de la Santé et de la Recherche Médicale, U1068, 13009 Marseille, France.,Institut Paoli-Calmettes, 13009 Marseille, France.,Aix-Marseille Université, 13284 Marseille, France.,Centre National de la Recherche Scientifique, UMR7258, 13273 Marseille, France
| | - Jean-Paul Borg
- Cell Polarity, Cell Signaling and Cancer, Equipe labellisée Ligue Contre le Cancer, Institut National de la Santé et de la Recherche Médicale, U1068, 13009 Marseille, France.,Institut Paoli-Calmettes, 13009 Marseille, France.,Aix-Marseille Université, 13284 Marseille, France.,Centre National de la Recherche Scientifique, UMR7258, 13273 Marseille, France
| | - Moritz Bünemann
- Institute of Pharmacology and Clinical Pharmacy, Biochemical-Pharmacological Center, University of Marburg, 35043 Marburg, Germany
| | - Stefan Offermanns
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany.,Medical Faculty, University of Frankfurt, 60590 Frankfurt am Main, Germany
| | - Jakub M Swiercz
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Thomas Worzfeld
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany .,Institute of Pharmacology, Biochemical-Pharmacological Center, University of Marburg, 35043 Marburg, Germany
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25
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Zwarts L, Goossens T, Clements J, Kang YY, Callaerts P. Axon Branch-Specific Semaphorin-1a Signaling in Drosophila Mushroom Body Development. Front Cell Neurosci 2016; 10:210. [PMID: 27656129 PMCID: PMC5011136 DOI: 10.3389/fncel.2016.00210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/23/2016] [Indexed: 11/25/2022] Open
Abstract
Correct wiring of the mushroom body (MB) neuropil in the Drosophila brain involves appropriate positioning of different axonal lobes, as well as the sister branches that develop from individual axons. This positioning requires the integration of various guidance cues provided by different cell types, which help the axons find their final positions within the neuropil. Semaphorins are well-known for their conserved roles in neuronal development and axon guidance. We investigated the role of Sema-1a in MB development more closely. We show that Sema-1a is expressed in the MBs as well as surrounding structures, including the glial transient interhemispheric fibrous ring, throughout development. By loss- and gain-of-function experiments, we show that the MB axons display lobe and sister branch-specific Sema-1a signaling, which controls different aspects of axon outgrowth and guidance. Furthermore, we demonstrate that these effects are modulated by the integration of MB intrinsic and extrinsic Sema-1a signaling pathways involving PlexA and PlexB. Finally, we also show a role for neuronal- glial interaction in Sema-1a dependent β-lobe outgrowth.
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Affiliation(s)
- Liesbeth Zwarts
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
| | - Tim Goossens
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
| | - Jason Clements
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
| | - Yuan Y Kang
- Department of Biology and Biochemistry, University of Houston, Houston, TX USA
| | - Patrick Callaerts
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
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26
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Perez-Branguli F, Zagar Y, Shanley DK, Graef IA, Chédotal A, Mitchell KJ. Reverse Signaling by Semaphorin-6A Regulates Cellular Aggregation and Neuronal Morphology. PLoS One 2016; 11:e0158686. [PMID: 27392094 PMCID: PMC4938514 DOI: 10.1371/journal.pone.0158686] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 06/20/2016] [Indexed: 12/28/2022] Open
Abstract
The transmembrane semaphorin, Sema6A, has important roles in axon guidance, cell migration and neuronal connectivity in multiple regions of the nervous system, mediated by context-dependent interactions with plexin receptors, PlxnA2 and PlxnA4. Here, we demonstrate that Sema6A can also signal cell-autonomously, in two modes, constitutively, or in response to higher-order clustering mediated by either PlxnA2-binding or chemically induced multimerisation. Sema6A activation stimulates recruitment of Abl to the cytoplasmic domain of Sema6A and phos¡phorylation of this cytoplasmic tyrosine kinase, as well as phosphorylation of additional cytoskeletal regulators. Sema6A reverse signaling affects the surface area and cellular complexity of non-neuronal cells and aggregation and neurite formation of primary neurons in vitro. Sema6A also interacts with PlxnA2 in cis, which reduces binding by PlxnA2 of Sema6A in trans but not vice versa. These experiments reveal the complex nature of Sema6A biochemical functions and the molecular logic of the context-dependent interactions between Sema6A and PlxnA2.
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Affiliation(s)
- Francesc Perez-Branguli
- Smurfit Institute of Genetics and Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Yvrick Zagar
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMR_S968, CNRS_UMR7210, Institut de la Vision, Paris, France
| | - Daniel K. Shanley
- Smurfit Institute of Genetics and Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Isabella A. Graef
- Department of Pathology, Stanford University Medical School, Stanford, California, United States of America
| | - Alain Chédotal
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMR_S968, CNRS_UMR7210, Institut de la Vision, Paris, France
| | - Kevin J. Mitchell
- Smurfit Institute of Genetics and Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
- * E-mail:
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27
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Goshima Y, Yamashita N, Nakamura F, Sasaki Y. Regulation of dendritic development by semaphorin 3A through novel intracellular remote signaling. Cell Adh Migr 2016; 10:627-640. [PMID: 27392015 DOI: 10.1080/19336918.2016.1210758] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Numerous cell adhesion molecules, extracellular matrix proteins and axon guidance molecules participate in neuronal network formation through local effects at axo-dendritic, axo-axonic or dendro-dendritic contact sites. In contrast, neurotrophins and their receptors play crucial roles in neural wiring by sending retrograde signals to remote cell bodies. Semaphorin 3A (Sema3A), a prototype of secreted type 3 semaphorins, is implicated in axon repulsion, dendritic branching and synapse formation via binding protein neuropilin-1 (NRP1) and the signal transducing protein PlexinAs (PlexAs) complex. This review focuses on Sema3A retrograde signaling that regulates dendritic localization of AMPA-type glutamate receptor GluA2 and dendritic patterning. This signaling is elicited by activation of NRP1 in growth cones and is propagated to cell bodies by dynein-dependent retrograde axonal transport of PlexAs. It also requires interaction between PlexAs and a high-affinity receptor for nerve growth factor, toropomyosin receptor kinase A. We propose a control mechanism by which retrograde Sema3A signaling regulates the glutamate receptor localization through trafficking of cis-interacting PlexAs with GluA2 along dendrites; this remote signaling may be an alternative mechanism to local adhesive contacts for neural network formation.
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Affiliation(s)
- Yoshio Goshima
- a Department of Molecular Pharmacology and Neurobiology , Yokohama City University Graduate School of Medicine , Yokohama , Japan
| | - Naoya Yamashita
- a Department of Molecular Pharmacology and Neurobiology , Yokohama City University Graduate School of Medicine , Yokohama , Japan.,c Department of Biology , Johns Hopkins University , Baltimore , MD , USA
| | - Fumio Nakamura
- a Department of Molecular Pharmacology and Neurobiology , Yokohama City University Graduate School of Medicine , Yokohama , Japan
| | - Yukio Sasaki
- b Functional Structural, Biology Laboratory, Department of Medical Life Science , Yokohama City University Graduate School of Medical Life Science , Suehirocho, Tsurumi-ku, Yokohama , Japan
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28
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Battistini C, Tamagnone L. Transmembrane semaphorins, forward and reverse signaling: have a look both ways. Cell Mol Life Sci 2016; 73:1609-22. [PMID: 26794845 PMCID: PMC11108563 DOI: 10.1007/s00018-016-2137-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 01/06/2023]
Abstract
Semaphorins are signaling molecules playing pivotal roles not only as axon guidance cues, but are also involved in the regulation of a range of biological processes, such as immune response, angiogenesis and invasive tumor growth. The main functional receptors for semaphorins are plexins, which are large single-pass transmembrane molecules. Semaphorin signaling through plexins-the "classical" forward signaling-affects cytoskeletal remodeling and integrin-dependent adhesion, consequently influencing cell migration. Intriguingly, semaphorins and plexins can interact not only in trans, but also in cis, leading to differentiated and highly regulated signaling outputs. Moreover, transmembrane semaphorins can also mediate a so-called "reverse" signaling, by acting not as ligands but rather as receptors, and initiate a signaling cascade through their own cytoplasmic domains. Semaphorin reverse signaling has been clearly demonstrated in fruit fly Sema1a, which is required to control motor axon defasciculation and target recognition during neuromuscular development. Sema1a invertebrate semaphorin is most similar to vertebrate class-6 semaphorins, and examples of semaphorin reverse signaling in mammalians have been described for these family members. Reverse signaling is also reported for other vertebrate semaphorin subsets, e.g. class-4 semaphorins, which bear potential PDZ-domain interaction motifs in their cytoplasmic regions. Therefore, thanks to their various signaling abilities, transmembrane semaphorins can play multifaceted roles both in developmental processes and in physiological as well as pathological conditions in the adult.
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Affiliation(s)
- Chiara Battistini
- Department of Oncology, University of Torino c/o IRCCS, Str. Prov. 142, 10060, Candiolo (TO), Italy
- Candiolo Cancer Institute, IRCCS-FPO, Str. Prov. 142, 10060, Candiolo (TO), Italy
| | - Luca Tamagnone
- Department of Oncology, University of Torino c/o IRCCS, Str. Prov. 142, 10060, Candiolo (TO), Italy.
- Candiolo Cancer Institute, IRCCS-FPO, Str. Prov. 142, 10060, Candiolo (TO), Italy.
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29
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Talsma AD, Chaves JF, LaMonaca A, Wieczorek ED, Palladino MJ. Genome-wide screen for modifiers of Na (+) /K (+) ATPase alleles identifies critical genetic loci. Mol Brain 2014; 7:89. [PMID: 25476251 PMCID: PMC4302446 DOI: 10.1186/s13041-014-0089-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 11/20/2014] [Indexed: 12/22/2022] Open
Abstract
Background Mutations affecting the Na+/ K+ATPase (a.k.a. the sodium-potassium pump) genes cause conditional locomotor phenotypes in flies and three distinct complex neurological diseases in humans. More than 50 mutations have been identified affecting the human ATP1A2 and ATP1A3 genes that are known to cause rapid-onset Dystonia Parkinsonism, familial hemiplegic migraine, alternating hemiplegia of childhood, and variants of familial hemiplegic migraine with neurological complications including seizures and various mood disorders. In flies, mutations affecting the ATPalpha gene have dramatic phenotypes including altered longevity, neural dysfunction, neurodegeneration, myodegeneration, and striking locomotor impairment. Locomotor defects can manifest as conditional bang-sensitive (BS) or temperature-sensitive (TS) paralysis: phenotypes well-suited for genetic screening. Results We performed a genome-wide deficiency screen using three distinct missense alleles of ATPalpha and conditional locomotor function assays to identify novel modifier loci. A secondary screen confirmed allele-specificity of the interactions and many of the interactions were mapped to single genes and subsequently validated. We successfully identified 64 modifier loci and used classical mutations and RNAi to confirm 50 single gene interactions. The genes identified include those with known function, several with unknown function or that were otherwise uncharacterized, and many loci with no described association with locomotor or Na+/K+ ATPase function. Conclusions We used an unbiased genome-wide screen to find regions of the genome containing elements important for genetic modulation of ATPalpha dysfunction. We have identified many critical regions and narrowed several of these to single genes. These data demonstrate there are many loci capable of modifying ATPalpha dysfunction, which may provide the basis for modifying migraine, locomotor and seizure dysfunction in animals. Electronic supplementary material The online version of this article (doi:10.1186/s13041-014-0089-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aaron D Talsma
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA. .,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA.
| | - John F Chaves
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA. .,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA.
| | - Alexandra LaMonaca
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA. .,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA.
| | - Emily D Wieczorek
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA. .,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA.
| | - Michael J Palladino
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA. .,Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, BST3 7042, Pittsburgh, PA, 15261, USA.
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30
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Andermatt I, Wilson NH, Bergmann T, Mauti O, Gesemann M, Sockanathan S, Stoeckli ET. Semaphorin 6B acts as a receptor in post-crossing commissural axon guidance. Development 2014; 141:3709-20. [PMID: 25209245 DOI: 10.1242/dev.112185] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Semaphorins are a large family of axon guidance molecules that are known primarily as ligands for plexins and neuropilins. Although class-6 semaphorins are transmembrane proteins, they have been implicated as ligands in different aspects of neural development, including neural crest cell migration, axon guidance and cerebellar development. However, the specific spatial and temporal expression of semaphorin 6B (Sema6B) in chick commissural neurons suggested a receptor role in axon guidance at the spinal cord midline. Indeed, in the absence of Sema6B, post-crossing commissural axons lacked an instructive signal directing them rostrally along the contralateral floorplate border, resulting in stalling at the exit site or even caudal turns. Truncated Sema6B lacking the intracellular domain was unable to rescue the loss-of-function phenotype, confirming a receptor function of Sema6B. In support of this, we demonstrate that Sema6B binds to floorplate-derived plexin A2 (PlxnA2) for navigation at the midline, whereas a cis-interaction between PlxnA2 and Sema6B on pre-crossing commissural axons may regulate the responsiveness of axons to floorplate-derived cues.
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Affiliation(s)
- Irwin Andermatt
- Institute of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Nicole H Wilson
- Institute of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Timothy Bergmann
- Institute of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Olivier Mauti
- Institute of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Matthias Gesemann
- Institute of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
| | - Shanthini Sockanathan
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
| | - Esther T Stoeckli
- Institute of Molecular Life Sciences and Neuroscience Center Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland
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31
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Abstract
Semaphorins are secreted and membrane-associated proteins that regulate many different developmental processes, including neural circuit assembly, bone formation and angiogenesis. Trans and cis interactions between semaphorins and their multimeric receptors trigger intracellular signal transduction networks that regulate cytoskeletal dynamics and influence cell shape, differentiation, motility and survival. Here and in the accompanying poster we provide an overview of the molecular biology of semaphorin signalling within the context of specific cell and developmental processes, highlighting the mechanisms that act to fine-tune, diversify and spatiotemporally control the effects of semaphorins.
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Affiliation(s)
- Bart C. Jongbloets
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, UMC Utrecht, 3451 PM Utrecht, The Netherlands
| | - R. Jeroen Pasterkamp
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, UMC Utrecht, 3451 PM Utrecht, The Netherlands
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32
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Abstract
Semaphorin family proteins are well-known axon guidance ligands. Recent studies indicate that certain transmembrane Semaphorins can also function as guidance receptors to mediate axon-axon attraction or repulsion. The mechanisms by which Semaphorin reverse signaling modulates axon-surface affinity, however, remain unknown. In this study, we reveal a novel mechanism underlying upregulation of axon-axon attraction by Semaphorin-1a (Sema1a) reverse signaling in the developing Drosophila visual system. Sema1a promotes the phosphorylation and activation of Moesin (Moe), a member of the ezrin/radixin/moesin family of proteins, and downregulates the level of active Rho1 in photoreceptor axons. We propose that Sema1a reverse signaling activates Moe, which in turn upregulates Fas2-mediated axon-axon attraction by inhibiting Rho1.
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33
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Ermanoska B, Motley WW, Leitão-Gonçalves R, Asselbergh B, Lee LH, De Rijk P, Sleegers K, Ooms T, Godenschwege TA, Timmerman V, Fischbeck KH, Jordanova A. CMT-associated mutations in glycyl- and tyrosyl-tRNA synthetases exhibit similar pattern of toxicity and share common genetic modifiers in Drosophila. Neurobiol Dis 2014; 68:180-9. [PMID: 24807208 DOI: 10.1016/j.nbd.2014.04.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 04/17/2014] [Accepted: 04/27/2014] [Indexed: 01/29/2023] Open
Abstract
Aminoacyl-tRNA synthetases are ubiquitously expressed proteins that charge tRNAs with their cognate amino acids. By ensuring the fidelity of protein synthesis, these enzymes are essential for the viability of every cell. Yet, mutations in six tRNA synthetases specifically affect the peripheral nerves and cause Charcot-Marie-Tooth (CMT) disease. The CMT-causing mutations in tyrosyl- and glycyl-tRNA synthetases (YARS and GARS, respectively) alter the activity of the proteins in a range of ways (some mutations do not impact charging function, while others abrogate it), making a loss of function in tRNA charging unlikely to be the cause of disease pathology. It is currently unknown which cellular mechanisms are triggered by the mutant enzymes and how this leads to neurodegeneration. Here, by expressing two pathogenic mutations (G240R, P234KY) in Drosophila, we generated a model for GARS-associated neuropathy. We observed compromised viability, and behavioral, electrophysiological and morphological impairment in flies expressing the cytoplasmic isoform of mutant GARS. Their features recapitulated several hallmarks of CMT pathophysiology and were similar to the phenotypes identified in our previously described Drosophila model of YARS-associated neuropathy. Furthermore, CG8316 and CG15599 - genes identified in a retinal degeneration screen to modify mutant YARS, also modified the mutant GARS phenotypes. Our study presents genetic evidence for common mutant-specific interactions between two CMT-associated aminoacyl-tRNA synthetases, lending support for a shared mechanism responsible for the synthetase-induced peripheral neuropathies.
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Affiliation(s)
- Biljana Ermanoska
- Molecular Neurogenomics Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium; Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium
| | - William W Motley
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ricardo Leitão-Gonçalves
- Molecular Neurogenomics Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium; Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium; Peripheral Neuropathy Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium
| | - Bob Asselbergh
- Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium; Centralized Service Facility, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium
| | - LaTasha H Lee
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Peter De Rijk
- Applied Molecular Genomics Unit, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium
| | - Kristel Sleegers
- Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium; Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium
| | - Tinne Ooms
- Molecular Neurogenomics Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium; Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium
| | - Tanja A Godenschwege
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Vincent Timmerman
- Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium; Peripheral Neuropathy Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium
| | - Kenneth H Fischbeck
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Albena Jordanova
- Molecular Neurogenomics Group, Department of Molecular Genetics, VIB, University of Antwerp, Antwerp 2610, Belgium; Neurogenetics Laboratory, Institute Born-Bunge, University of Antwerp, Antwerp 2610, Belgium.
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Semaphorins and the dynamic regulation of synapse assembly, refinement, and function. Curr Opin Neurobiol 2014; 27:1-7. [PMID: 24598309 DOI: 10.1016/j.conb.2014.02.005] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/21/2014] [Accepted: 02/06/2014] [Indexed: 01/13/2023]
Abstract
Semaphorins are phylogenetically conserved proteins expressed in most organ systems, including the nervous system. Following their description as axon guidance cues, semaphorins have been implicated in multiple aspects of nervous system development. Semaphorins are key regulators of neural circuit assembly, neuronal morphogenesis, assembly of excitatory and inhibitory synapses, and synaptic refinement. Semaphorins contribute to the balance between excitatory and inhibitory synaptic transmission, and electrical activity can modulate semaphorin signaling in neurons. This interplay between guidance cue signaling and electrical activity has the potential to sculpt the wiring of neural circuits and to modulate their function.
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Chávez-Galarza J, Henriques D, Johnston JS, Azevedo JC, Patton JC, Muñoz I, De la Rúa P, Pinto MA. Signatures of selection in the Iberian honey bee (Apis mellifera iberiensis) revealed by a genome scan analysis of single nucleotide polymorphisms. Mol Ecol 2013; 22:5890-907. [PMID: 24118235 DOI: 10.1111/mec.12537] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 09/12/2013] [Accepted: 09/19/2013] [Indexed: 12/30/2022]
Abstract
Understanding the genetic mechanisms of adaptive population divergence is one of the most fundamental endeavours in evolutionary biology and is becoming increasingly important as it will allow predictions about how organisms will respond to global environmental crisis. This is particularly important for the honey bee, a species of unquestionable ecological and economical importance that has been exposed to increasing human-mediated selection pressures. Here, we conducted a single nucleotide polymorphism (SNP)-based genome scan in honey bees collected across an environmental gradient in Iberia and used four FST -based outlier tests to identify genomic regions exhibiting signatures of selection. Additionally, we analysed associations between genetic and environmental data for the identification of factors that might be correlated or act as selective pressures. With these approaches, 4.4% (17 of 383) of outlier loci were cross-validated by four FST -based methods, and 8.9% (34 of 383) were cross-validated by at least three methods. Of the 34 outliers, 15 were found to be strongly associated with one or more environmental variables. Further support for selection, provided by functional genomic information, was particularly compelling for SNP outliers mapped to different genes putatively involved in the same function such as vision, xenobiotic detoxification and innate immune response. This study enabled a more rigorous consideration of selection as the underlying cause of diversity patterns in Iberian honey bees, representing an important first step towards the identification of polymorphisms implicated in local adaptation and possibly in response to recent human-mediated environmental changes.
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Affiliation(s)
- Julio Chávez-Galarza
- Mountain Research Centre (CIMO), Polytechnic Institute of Bragança, Campus de Sta. Apolónia, Apartado 1172, 5301-855, Bragança, Portugal
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36
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Pfister A, Johnson A, Ellers O, Horch HW. Quantification of dendritic and axonal growth after injury to the auditory system of the adult cricket Gryllus bimaculatus. Front Physiol 2013; 3:367. [PMID: 23986706 PMCID: PMC3750946 DOI: 10.3389/fphys.2012.00367] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/27/2012] [Indexed: 12/13/2022] Open
Abstract
Dendrite and axon growth and branching during development are regulated by a complex set of intracellular and external signals. However, the cues that maintain or influence adult neuronal morphology are less well understood. Injury and deafferentation tend to have negative effects on adult nervous systems. An interesting example of injury-induced compensatory growth is seen in the cricket, Gryllus bimaculatus. After unilateral loss of an ear in the adult cricket, auditory neurons within the central nervous system (CNS) sprout to compensate for the injury. Specifically, after being deafferented, ascending neurons (AN-1 and AN-2) send dendrites across the midline of the prothoracic ganglion where they receive input from auditory afferents that project through the contralateral auditory nerve (N5). Deafferentation also triggers contralateral N5 axonal growth. In this study, we quantified AN dendritic and N5 axonal growth at 30 h, as well as at 3, 5, 7, 14, and 20 days after deafferentation in adult crickets. Significant differences in the rates of dendritic growth between males and females were noted. In females, dendritic growth rates were non-linear; a rapid burst of dendritic extension in the first few days was followed by a plateau reached at 3 days after deafferentation. In males, however, dendritic growth rates were linear, with dendrites growing steadily over time and reaching lengths, on average, twice as long as in females. On the other hand, rates of N5 axonal growth showed no significant sexual dimorphism and were linear. Within each animal, the growth rates of dendrites and axons were not correlated, indicating that independent factors likely influence dendritic and axonal growth in response to injury in this system. Our findings provide a basis for future study of the cellular features that allow differing dendrite and axon growth patterns as well as sexually dimorphic dendritic growth in response to deafferentation.
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Affiliation(s)
- Alexandra Pfister
- Department of Invertebrate Zoology, American Museum of Natural History New York, NY, USA
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37
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Nesler KR, Sand RI, Symmes BA, Pradhan SJ, Boin NG, Laun AE, Barbee SA. The miRNA pathway controls rapid changes in activity-dependent synaptic structure at the Drosophila melanogaster neuromuscular junction. PLoS One 2013; 8:e68385. [PMID: 23844193 PMCID: PMC3699548 DOI: 10.1371/journal.pone.0068385] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/29/2013] [Indexed: 01/12/2023] Open
Abstract
It is widely accepted that long-term changes in synapse structure and function are mediated by rapid activity-dependent gene transcription and new protein synthesis. A growing amount of evidence suggests that the microRNA (miRNA) pathway plays an important role in coordinating these processes. Despite recent advances in this field, there remains a critical need to identify specific activity-regulated miRNAs as well as their key messenger RNA (mRNA) targets. To address these questions, we used the larval Drosophila melanogaster neuromuscular junction (NMJ) as a model synapse in which to identify novel miRNA-mediated mechanisms that control activity-dependent synaptic growth. First, we developed a screen to identify miRNAs differentially regulated in the larval CNS following spaced synaptic stimulation. Surprisingly, we identified five miRNAs (miRs-1, -8, -289, -314, and -958) that were significantly downregulated by activity. Neuronal misexpression of three miRNAs (miRs-8, -289, and -958) suppressed activity-dependent synaptic growth suggesting that these miRNAs control the translation of biologically relevant target mRNAs. Functional annotation cluster analysis revealed that putative targets of miRs-8 and -289 are significantly enriched in clusters involved in the control of neuronal processes including axon development, pathfinding, and growth. In support of this, miR-8 regulated the expression of a wingless 3′UTR (wg 3′ untranslated region) reporter in vitro. Wg is an important presynaptic regulatory protein required for activity-dependent axon terminal growth at the fly NMJ. In conclusion, our results are consistent with a model where key activity-regulated miRNAs are required to coordinate the expression of genes involved in activity-dependent synaptogenesis.
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Affiliation(s)
- Katherine R. Nesler
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Robert I. Sand
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Breanna A. Symmes
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Sarala J. Pradhan
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Nathan G. Boin
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Anna E. Laun
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
| | - Scott A. Barbee
- Department of Biological Sciences and Eleanor Roosevelt Institute, University of Denver, Denver, Colorado, United States of America
- Molecular and Cellular Biophysics Program, University of Denver, Denver, Colorado, United States of America
- Colorado Intellectual and Developmental Disabilities Research Center (IDDRC), University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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Emerson MM, Long JB, Van Vactor D. Drosophila semaphorin2b is required for the axon guidance of a subset of embryonic neurons. Dev Dyn 2013; 242:861-73. [PMID: 23606306 PMCID: PMC3739952 DOI: 10.1002/dvdy.23979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Revised: 03/20/2013] [Accepted: 03/21/2013] [Indexed: 12/26/2022] Open
Abstract
Background: The process of axon guidance is important in establishing functional neural circuits. The differential expression of cell-autonomous axon guidance factors is crucial for allowing axons of different neurons to take unique trajectories in response to spatially and temporally restricted cell non-autonomous axon guidance factors. A key motivation in the field is to provide adequate explanations for axon behavior with respect to the differential expression of these factors. Results: We report the characterization of a predicted secreted semaphorin family member, semaphorin2b (Sema-2b) in Drosophila embryonic axon guidance. Misexpression of Sema-2b in neurons causes highly penetrant axon guidance phenotypes in specific longitudinal and motoneuron pathways; however, expression of Sema-2b in muscles traversed by these motoneurons has no effect on axon guidance. In Sema-2b loss-of-function embryos, specific motoneuron and interneuron axon pathways display guidance defects. Specific visualization of the neurons that normally express Sema-2b reveals that this neuronal cohort is strongly affected by Sema-2b loss-of-function alleles. Conclusions: While secreted semaphorins have been implicated as cell non-autonomous chemorepellants in a variety of contexts, here we report previously undescribed Sema-2b loss-of-function and misexpression phenotypes that are consistent with a cell-autonomous role for Sema-2b. Developmental Dynamics 242:861–873, 2013. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Mark M Emerson
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
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Mizumoto K, Shen K. Interaxonal interaction defines tiled presynaptic innervation in C. elegans. Neuron 2013; 77:655-66. [PMID: 23439119 DOI: 10.1016/j.neuron.2012.12.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2012] [Indexed: 10/27/2022]
Abstract
VIDEO ABSTRACT Cellular interactions between neighboring axons are essential for global topographic map formation. Here we show that axonal interactions also precisely instruct the location of synapses. Motoneurons form en passant synapses in Caenorhabditis elegans. Although axons from the same neuron class significantly overlap, each neuron innervates a unique and tiled segment of the muscle field by restricting its synapses to a distinct subaxonal domain-a phenomenon we term synaptic tiling. Using DA8 and DA9 motoneurons, we found that the synaptic tiling requires the PlexinA4 homolog, PLX-1, and two transmembrane semaphorins. In the plexin or semaphorin mutants, synaptic domains from both neurons expand and overlap with each other without guidance defects. In a semaphorin-dependent manner, PLX-1 is concentrated at the synapse-free axonal segment, delineating the tiling border. Furthermore, plexin inhibits presynapse formation by suppressing synaptic F-actin through its cytoplasmic GTPase-activating protein (GAP) domain. Hence, contact-dependent, intra-axonal plexin signaling specifies synaptic circuits by inhibiting synapse formation at the subcellular loci.
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Affiliation(s)
- Kota Mizumoto
- Department of Biology, Howard Hughes Medical Institute, Stanford University, 385 Serra Mall, Stanford, CA 94305, USA
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40
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Enneking EM, Kudumala SR, Moreno E, Stephan R, Boerner J, Godenschwege TA, Pielage J. Transsynaptic coordination of synaptic growth, function, and stability by the L1-type CAM Neuroglian. PLoS Biol 2013; 11:e1001537. [PMID: 23610557 PMCID: PMC3627646 DOI: 10.1371/journal.pbio.1001537] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 03/06/2013] [Indexed: 12/27/2022] Open
Abstract
Experiments in peripheral and central synapses reveal the regulatory mechanisms that enable trans-synaptic control of synapse development and maintenance by the L1-type CAM Neuroglian. The precise control of synaptic connectivity is essential for the development and function of neuronal circuits. While there have been significant advances in our understanding how cell adhesion molecules mediate axon guidance and synapse formation, the mechanisms controlling synapse maintenance or plasticity in vivo remain largely uncharacterized. In an unbiased RNAi screen we identified the Drosophila L1-type CAM Neuroglian (Nrg) as a central coordinator of synapse growth, function, and stability. We demonstrate that the extracellular Ig-domains and the intracellular Ankyrin-interaction motif are essential for synapse development and stability. Nrg binds to Ankyrin2 in vivo and mutations reducing the binding affinities to Ankyrin2 cause an increase in Nrg mobility in motoneurons. We then demonstrate that the Nrg–Ank2 interaction controls the balance of synapse growth and stability at the neuromuscular junction. In contrast, at a central synapse, transsynaptic interactions of pre- and postsynaptic Nrg require a dynamic, temporal and spatial, regulation of the intracellular Ankyrin-binding motif to coordinate pre- and postsynaptic development. Our study at two complementary model synapses identifies the regulation of the interaction between the L1-type CAM and Ankyrin as an important novel module enabling local control of synaptic connectivity and function while maintaining general neuronal circuit architecture. The function of neuronal circuits relies on precise connectivity, and processes like learning and memory involve refining this connectivity through the selective formation and elimination of synapses. Cell adhesion molecules (CAMs) that directly mediate cell–cell interactions at synaptic contacts are thought to mediate this structural synaptic plasticity. In this study, we used an unbiased genetic screen to identify the Drosophila L1-type CAM Neuroglian as a central regulator of synapse formation and maintenance. We show that the intracellular Ankyrin interaction motif, which links Neuroglian to the cytoskeleton, is an essential regulatory site for Neuroglian mobility, adhesion, and synaptic function. In motoneurons, the strength of Ankyrin binding directly controls the balance between synapse formation and maintenance. At a central synapse, however, a dynamic regulation of the Neuroglian–Ankyrin interaction is required to coordinate transsynaptic development. Our study identifies the interaction of the L1-type CAM with Ankyrin as a novel regulatory module enabling local and precise control of synaptic connectivity without altering general neuronal circuit architecture. This interaction is relevant for normal nervous system development and disease as mutations in L1-type CAMs cause mental retardation and psychiatric diseases in humans.
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Affiliation(s)
- Eva-Maria Enneking
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | | | - Eliza Moreno
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Raiko Stephan
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jana Boerner
- Florida Atlantic University, Boca Raton, Florida, United States of America
| | - Tanja A. Godenschwege
- Florida Atlantic University, Boca Raton, Florida, United States of America
- * E-mail: (JP); (TAG)
| | - Jan Pielage
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
- * E-mail: (JP); (TAG)
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41
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Multiple interactions control synaptic layer specificity in the Drosophila visual system. Neuron 2013; 77:299-310. [PMID: 23352166 PMCID: PMC3684158 DOI: 10.1016/j.neuron.2012.11.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2012] [Indexed: 01/03/2023]
Abstract
How neurons form synapses within specific layers remains poorly understood. In the Drosophila medulla, neurons target to discrete layers in a precise fashion. Here we demonstrate that the targeting of L3 neurons to a specific layer occurs in two steps. Initially, L3 growth cones project to a common domain in the outer medulla, overlapping with the growth cones of other neurons destined for a different layer through the redundant functions of N-Cadherin (CadN) and Semaphorin-1a (Sema-1a). CadN mediates adhesion within the domain and Sema-1a mediates repulsion through Plexin A (PlexA) expressed in an adjacent region. Subsequently, L3 growth cones segregate from the domain into their target layer in part through Sema-1a/PlexA-dependent remodeling. Together, our results and recent studies argue that the early medulla is organized into common domains, comprising processes bound for different layers, and that discrete layers later emerge through successive interactions between processes within domains and developing layers.
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42
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Jeong S, Juhaszova K, Kolodkin AL. The Control of semaphorin-1a-mediated reverse signaling by opposing pebble and RhoGAPp190 functions in drosophila. Neuron 2013. [PMID: 23177958 DOI: 10.1016/j.neuron.2012.09.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Transmembrane semaphorins (Semas) serve evolutionarily conserved guidance roles, and some function as both ligands and receptors. However, the molecular mechanisms underlying the transduction of these signals to the cytoskeleton remain largely unknown. We have identified two direct regulators of Rho family small GTPases, pebble (a Rho guanine nucleotide exchange factor [GEF]) and RhoGAPp190 (a GTPase activating protein [GAP]), that show robust interactions with the cytoplasmic domain of the Drosophila Sema-1a protein. Neuronal pebble and RhoGAPp190 are required to control motor axon defasciculation at specific pathway choice points and also for target recognition during Drosophila neuromuscular development. Sema-1a-mediated motor axon defasciculation is promoted by pebble and inhibited by RhoGAPp190. Genetic analyses show that opposing pebble and RhoGAPp190 functions mediate Sema-1a reverse signaling through the regulation of Rho1 activity. Therefore, pebble and RhoGAPp190 transduce transmembrane semaphorin-mediated guidance cue information that regulates the establishment of neuronal connectivity during Drosophila development.
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Affiliation(s)
- Sangyun Jeong
- Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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43
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Baudet ML, Bellon A, Holt CE. Role of microRNAs in Semaphorin function and neural circuit formation. Semin Cell Dev Biol 2012; 24:146-55. [PMID: 23219835 DOI: 10.1016/j.semcdb.2012.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 10/19/2012] [Accepted: 11/28/2012] [Indexed: 01/23/2023]
Abstract
Since the discovery of the first microRNA (miRNA) almost 20 years ago, insight into their functional role has gradually been accumulating. This class of non-coding RNAs has recently been implicated as key molecular regulators in the biology of most eukaryotic cells, contributing to the physiology of various systems including immune, cardiovascular, nervous systems and also to the pathophysiology of cancers. Interestingly, Semaphorins, a class of evolutionarily conserved signalling molecules, are acknowledged to play major roles in these systems also. This, combined with the fact that Semaphorin signalling requires tight spatiotemporal regulation, a hallmark of miRNA expression, suggests that miRNAs could be crucial regulators of Semaphorin function. Here, we review evidence suggesting that Semaphorin signalling is regulated by miRNAs in various systems in health and disease. In particular, we focus on neural circuit formation, including axon guidance, where Semaphorin function was first discovered.
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44
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Grondona JM, Hoyo-Becerra C, Visser R, Fernández-Llebrez P, López-Ávalos MD. The subcommissural organ and the development of the posterior commissure. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 296:63-137. [PMID: 22559938 DOI: 10.1016/b978-0-12-394307-1.00002-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Growing axons navigate through the developing brain by means of axon guidance molecules. Intermediate targets producing such signal molecules are used as guideposts to find distal targets. Glial, and sometimes neuronal, midline structures represent intermediate targets when axons cross the midline to reach the contralateral hemisphere. The subcommissural organ (SCO), a specialized neuroepithelium located at the dorsal midline underneath the posterior commissure, releases SCO-spondin, a large glycoprotein belonging to the thrombospondin superfamily that shares molecular domains with axonal pathfinding molecules. Several evidences suggest that the SCO could be involved in the development of the PC. First, both structures display a close spatiotemporal relationship. Second, certain mutants lacking an SCO present an abnormal PC. Third, some axonal guidance molecules are expressed by SCO cells. Finally, SCO cells, the Reissner's fiber (the aggregated form of SCO-spondin), or synthetic peptides from SCO-spondin affect the neurite outgrowth or neuronal aggregation in vitro.
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Affiliation(s)
- Jesús M Grondona
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Spain.
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45
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Tillo M, Ruhrberg C, Mackenzie F. Emerging roles for semaphorins and VEGFs in synaptogenesis and synaptic plasticity. Cell Adh Migr 2012; 6:541-6. [PMID: 23076132 PMCID: PMC3547901 DOI: 10.4161/cam.22408] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Synapse formation, maintenance and plasticity are critical for the correct function of the nervous system and its target organs. During development, these processes enable the establishment of appropriate neural circuits. During adulthood, they allow adaptation to both physiological and environmental changes. In this review, we discuss emerging roles for two families of classical axon and vascular guidance cues in synaptogenesis and synaptic plasticity, the semaphorins and the vascular endothelial growth factors (VEGFs). Their contribution to synapse formation and function add a new facet to the spectrum of overlapping and complementary roles for these molecules in development, adulthood and disease.
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Affiliation(s)
- Miguel Tillo
- Institute of Ophthalmology, University College London, London, UK
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46
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Eickhoff R, Bicker G. Developmental expression of cell recognition molecules in the mushroom body and antennal lobe of the locust Locusta migratoria. J Comp Neurol 2012; 520:2021-40. [PMID: 22173776 DOI: 10.1002/cne.23026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We examined the development of olfactory neuropils in the hemimetabolous insect Locusta migratoria with an emphasis on the mushroom bodies, protocerebral integration centers implicated in memory formation. Using a marker of the cyclic adenosine monophosphate (cAMP) signaling cascade and lipophilic dye labeling, we obtained new insights into mushroom body organization by resolving previously unrecognized accessory lobelets arising from Class III Kenyon cells. We utilized antibodies against axonal guidance cues, such as the cell surface glycoproteins Semaphorin 1a (Sema 1a) and Fasciclin I (Fas I), as embryonic markers to compile a comprehensive atlas of mushroom body development. During embryogenesis, all neuropils of the olfactory pathway transiently expressed Sema 1a. The immunoreactivity was particularly strong in developing mushroom bodies. During late embryonic stages, Sema 1a expression in the mushroom bodies became restricted to a subset of Kenyon cells in the core region of the peduncle. Sema 1a was differentially sorted to the Kenyon cell axons and absent in the dendrites. In contrast to Drosophila, locust mushroom bodies and antennal lobes expressed Fas I, but not Fas II. While Fas I immunoreactivity was widely distributed in the midbrain during embryogenesis, labeling persisted into adulthood only in the mushroom bodies and antennal lobes. Kenyon cells proliferated throughout the larval stages. Their neurites retained the embryonic expression pattern of Sema 1a and Fas I, suggesting a role for these molecules in developmental mushroom body plasticity. Our study serves as an initial step toward functional analyses of Sema 1a and Fas I expression during locust mushroom body formation.
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Affiliation(s)
- René Eickhoff
- University of Veterinary Medicine Hannover, Division of Cell Biology, D-30173 Hannover, Germany
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47
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Abstract
Semaphorins are key players in the control of neural circuit development. Recent studies have uncovered several exciting and novel aspects of neuronal semaphorin signalling in various cellular processes--including neuronal polarization, topographical mapping and axon sorting--that are crucial for the assembly of functional neuronal connections. This progress is important for further understanding the many neuronal and non-neuronal functions of semaphorins and for gaining insight into their emerging roles in the perturbed neural connectivity that is observed in some diseases. This Review discusses recent advances in semaphorin research, focusing on novel aspects of neuronal semaphorin receptor regulation and previously unexplored cellular functions of semaphorins in the nervous system.
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48
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Stern M, Scheiblich H, Eickhoff R, Didwischus N, Bicker G. Regeneration of olfactory afferent axons in the locust brain. J Comp Neurol 2012; 520:679-93. [DOI: 10.1002/cne.22770] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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49
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Kuzirian MS, Paradis S. Emerging themes in GABAergic synapse development. Prog Neurobiol 2011; 95:68-87. [PMID: 21798307 DOI: 10.1016/j.pneurobio.2011.07.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/30/2011] [Accepted: 07/03/2011] [Indexed: 12/25/2022]
Abstract
Glutamatergic synapse development has been rigorously investigated for the past two decades at both the molecular and cell biological level yet a comparable intensity of investigation into the cellular and molecular mechanisms of GABAergic synapse development has been lacking until relatively recently. This review will provide a detailed overview of the current understanding of GABAergic synapse development with a particular emphasis on assembly of synaptic components, molecular mechanisms of synaptic development, and a subset of human disorders which manifest when GABAergic synapse development is disrupted. An unexpected and emerging theme from these studies is that glutamatergic and GABAergic synapse development share a number of overlapping molecular and cell biological mechanisms that will be emphasized in this review.
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Affiliation(s)
- Marissa S Kuzirian
- Brandeis Univeristy, Department of Biology, National Center for Behavioral Genomics, Volen Center for Complex Systems, Waltham, MA 02453, USA
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50
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Plexin a-semaphorin-1a reverse signaling regulates photoreceptor axon guidance in Drosophila. J Neurosci 2010; 30:12151-6. [PMID: 20826677 DOI: 10.1523/jneurosci.1494-10.2010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
While it is well established that Semaphorin family proteins function as axon guidance ligands in invertebrates and vertebrates, several recent studies indicate that the Drosophila Semaphorin-1a (Sema1a), a transmembrane Semaphorin, can also function as a receptor during neural development. The regulator of Sema1a reverse signaling, however, remains unknown. In this study, we show that like Sema1a, the well known Semaphorin receptor Plexin A (PlexA), is required for the proper guidance of photoreceptor (R cell) axons in the Drosophila visual system. Loss of PlexA, like loss of semala, disrupted the association of R-cell growth cones in the optic lobe. Conversely, overexpression of PlexA, like overexpression of sema1a, induced the hyperfasciculation of R-cell axons. Unlike Sema1a, however, the cytoplasmic domain of PlexA is dispensable. Epistasis analysis suggests that PlexA functions upstream of semala. And PlexA and sema1a interact genetically with Rho1. We propose that PlexA regulates Semala reverse signaling in the Drosophila visual system.
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