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Tal T, Myhre O, Fritsche E, Rüegg J, Craenen K, Aiello-Holden K, Agrillo C, Babin PJ, Escher BI, Dirven H, Hellsten K, Dolva K, Hessel E, Heusinkveld HJ, Hadzhiev Y, Hurem S, Jagiello K, Judzinska B, Klüver N, Knoll-Gellida A, Kühne BA, Leist M, Lislien M, Lyche JL, Müller F, Colbourne JK, Neuhaus W, Pallocca G, Seeger B, Scharkin I, Scholz S, Spjuth O, Torres-Ruiz M, Bartmann K. New approach methods to assess developmental and adult neurotoxicity for regulatory use: a PARC work package 5 project. FRONTIERS IN TOXICOLOGY 2024; 6:1359507. [PMID: 38742231 PMCID: PMC11089904 DOI: 10.3389/ftox.2024.1359507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/18/2024] [Indexed: 05/16/2024] Open
Abstract
In the European regulatory context, rodent in vivo studies are the predominant source of neurotoxicity information. Although they form a cornerstone of neurotoxicological assessments, they are costly and the topic of ethical debate. While the public expects chemicals and products to be safe for the developing and mature nervous systems, considerable numbers of chemicals in commerce have not, or only to a limited extent, been assessed for their potential to cause neurotoxicity. As such, there is a societal push toward the replacement of animal models with in vitro or alternative methods. New approach methods (NAMs) can contribute to the regulatory knowledge base, increase chemical safety, and modernize chemical hazard and risk assessment. Provided they reach an acceptable level of regulatory relevance and reliability, NAMs may be considered as replacements for specific in vivo studies. The European Partnership for the Assessment of Risks from Chemicals (PARC) addresses challenges to the development and implementation of NAMs in chemical risk assessment. In collaboration with regulatory agencies, Project 5.2.1e (Neurotoxicity) aims to develop and evaluate NAMs for developmental neurotoxicity (DNT) and adult neurotoxicity (ANT) and to understand the applicability domain of specific NAMs for the detection of endocrine disruption and epigenetic perturbation. To speed up assay time and reduce costs, we identify early indicators of later-onset effects. Ultimately, we will assemble second-generation developmental neurotoxicity and first-generation adult neurotoxicity test batteries, both of which aim to provide regulatory hazard and risk assessors and industry stakeholders with robust, speedy, lower-cost, and informative next-generation hazard and risk assessment tools.
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Affiliation(s)
- Tamara Tal
- Helmholtz Centre for Environmental Research – UFZ, Chemicals in the Environment Research Section, Leipzig, Germany
- University of Leipzig, Medical Faculty, Leipzig, Germany
| | - Oddvar Myhre
- Norwegian Institute of Public Health – NIPH, Department of Chemical Toxicology, Oslo, Norway
| | - Ellen Fritsche
- IUF – Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
- DNTOX GmbH, Düsseldorf, Germany
- Swiss Centre for Applied Human Toxicology, University of Basel, Basel, Switzerland
| | - Joëlle Rüegg
- Uppsala University, Department of Organismal Biology, Uppsala, Sweden
| | - Kai Craenen
- European Chemicals Agency (ECHA), Helsinki, Finland
| | | | - Caroline Agrillo
- Uppsala University, Department of Organismal Biology, Uppsala, Sweden
| | - Patrick J. Babin
- Université de Bordeaux, Institut National de la Santé et de la Recherche Médicale (INSERM), Maladies Rares: Génétique et Métabolisme (MRGM), Pessac, France
| | - Beate I. Escher
- Helmholtz Centre for Environmental Research – UFZ, Chemicals in the Environment Research Section, Leipzig, Germany
| | - Hubert Dirven
- Norwegian Institute of Public Health – NIPH, Department of Chemical Toxicology, Oslo, Norway
| | | | - Kristine Dolva
- University of Oslo, Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, Olso, Norway
| | - Ellen Hessel
- Dutch Nation Institute for Public Health and the Environment (RIVM), Centre for Health Protection, Bilthoven, Netherlands
| | - Harm J. Heusinkveld
- Dutch Nation Institute for Public Health and the Environment (RIVM), Centre for Health Protection, Bilthoven, Netherlands
| | - Yavor Hadzhiev
- University of Birmingham, Centre for Environmental Research and Justice, Birmingham, UK
| | - Selma Hurem
- Norwegian University of Life Sciences (NMBU), Faculty of Veterinary Medicine, Ås, Norway
| | - Karolina Jagiello
- University of Gdansk, Laboratory of Environmental Chemoinformatics, Gdansk, Poland
| | - Beata Judzinska
- University of Gdansk, Laboratory of Environmental Chemoinformatics, Gdansk, Poland
| | - Nils Klüver
- Helmholtz Centre for Environmental Research – UFZ, Chemicals in the Environment Research Section, Leipzig, Germany
| | - Anja Knoll-Gellida
- Université de Bordeaux, Institut National de la Santé et de la Recherche Médicale (INSERM), Maladies Rares: Génétique et Métabolisme (MRGM), Pessac, France
| | - Britta A. Kühne
- University of Veterinary Medicine Hannover, Foundation, Institute for Food Quality and Food Safety, Hannover, Germany
| | - Marcel Leist
- University of Konstanz, In Vitro Toxicology and Biomedicine/CAAT-Europe, Konstanz, Germany
| | - Malene Lislien
- Norwegian Institute of Public Health – NIPH, Department of Chemical Toxicology, Oslo, Norway
| | - Jan L. Lyche
- Norwegian University of Life Sciences (NMBU), Faculty of Veterinary Medicine, Ås, Norway
| | - Ferenc Müller
- University of Birmingham, Centre for Environmental Research and Justice, Birmingham, UK
| | - John K. Colbourne
- University of Birmingham, Centre for Environmental Research and Justice, Birmingham, UK
| | - Winfried Neuhaus
- AIT Austrian Institute of Technology GmbH, Competence Unit Molecular Diagnostics, Center Health and Bioresources, Vienna, Austria
- Danube Private University, Faculty of Dentistry and Medicine, Department of Medicine, Krems, Austria
| | - Giorgia Pallocca
- University of Konstanz, In Vitro Toxicology and Biomedicine/CAAT-Europe, Konstanz, Germany
| | - Bettina Seeger
- University of Veterinary Medicine Hannover, Foundation, Institute for Food Quality and Food Safety, Hannover, Germany
| | - Ilka Scharkin
- IUF – Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Stefan Scholz
- Helmholtz Centre for Environmental Research – UFZ, Chemicals in the Environment Research Section, Leipzig, Germany
| | - Ola Spjuth
- Uppsala University and Science for Life Laboratory, Department of Pharmaceutical Biosciences, Uppsala, Sweden
| | - Monica Torres-Ruiz
- Instituto de Salud Carlos III (ISCIII), Centro Nacional de Sanidad Ambiental (CNSA), Environmental Toxicology Unit, Majadahonda, Spain
| | - Kristina Bartmann
- IUF – Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
- DNTOX GmbH, Düsseldorf, Germany
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2
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D'Elia KP, Hameedy H, Goldblatt D, Frazel P, Kriese M, Zhu Y, Hamling KR, Kawakami K, Liddelow SA, Schoppik D, Dasen JS. Determinants of motor neuron functional subtypes important for locomotor speed. Cell Rep 2023; 42:113049. [PMID: 37676768 PMCID: PMC10600875 DOI: 10.1016/j.celrep.2023.113049] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/12/2023] [Accepted: 08/11/2023] [Indexed: 09/09/2023] Open
Abstract
Locomotion requires precise control of the strength and speed of muscle contraction and is achieved by recruiting functionally distinct subtypes of motor neurons (MNs). MNs are essential to movement and differentially susceptible in disease, but little is known about how MNs acquire functional subtype-specific features during development. Using single-cell RNA profiling in embryonic and larval zebrafish, we identify novel and conserved molecular signatures for MN functional subtypes and identify genes expressed in both early post-mitotic and mature MNs. Assessing MN development in genetic mutants, we define a molecular program essential for MN functional subtype specification. Two evolutionarily conserved transcription factors, Prdm16 and Mecom, are both functional subtype-specific determinants integral for fast MN development. Loss of prdm16 or mecom causes fast MNs to develop transcriptional profiles and innervation similar to slow MNs. These results reveal the molecular diversity of vertebrate axial MNs and demonstrate that functional subtypes are specified through intrinsic transcriptional codes.
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Affiliation(s)
- Kristen P D'Elia
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Hanna Hameedy
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Dena Goldblatt
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA; Center for Neural Science, New York University, New York, NY, USA
| | - Paul Frazel
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Mercer Kriese
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Yunlu Zhu
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kyla R Hamling
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Japan
| | - Shane A Liddelow
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - David Schoppik
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA.
| | - Jeremy S Dasen
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA.
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3
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Tomoi T, Tameshige T, Betsuyaku E, Hamada S, Sakamoto J, Uchida N, Torii K, Shimizu KK, Tamada Y, Urawa H, Okada K, Fukuda H, Tatematsu K, Kamei Y, Betsuyaku S. Targeted single-cell gene induction by optimizing the dually regulated CRE/ loxP system by a newly defined heat-shock promoter and the steroid hormone in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2023; 14:1171531. [PMID: 37351202 PMCID: PMC10283073 DOI: 10.3389/fpls.2023.1171531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/28/2023] [Indexed: 06/24/2023]
Abstract
Multicellular organisms rely on intercellular communication systems to organize their cellular functions. In studies focusing on intercellular communication, the key experimental techniques include the generation of chimeric tissue using transgenic DNA recombination systems represented by the CRE/loxP system. If an experimental system enables the induction of chimeras at highly targeted cell(s), it will facilitate the reproducibility and precision of experiments. However, multiple technical limitations have made this challenging. The stochastic nature of DNA recombination events, especially, hampers reproducible generation of intended chimeric patterns. Infrared laser-evoked gene operator (IR-LEGO), a microscopic system that irradiates targeted cells using an IR laser, can induce heat shock-mediated expression of transgenes, for example, CRE recombinase gene, in the cells. In this study, we developed a method that induces CRE/loxP recombination in the target cell(s) of plant roots and leaves in a highly specific manner. We combined IR-LEGO, an improved heat-shock-specific promoter, and dexamethasone-dependent regulation of CRE. The optimal IR-laser power and irradiation duration were estimated via exhaustive irradiation trials and subsequent statistical modeling. Under optimized conditions, CRE/loxP recombination was efficiently induced without cellular damage. We also found that the induction efficiency varied among tissue types and cellular sizes. The developed method offers an experimental system to generate a precisely designed chimeric tissue, and thus, will be useful for analyzing intercellular communication at high resolution in roots and leaves.
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Affiliation(s)
- Takumi Tomoi
- Center for Innovation Support, Institute for Social Innovation and Cooperation, Utsunomiya University, Utsunomiya, Japan
- School of Engineering, Utsunomiya University, Utsunomiya, Japan
- Laboratory for Biothermology, National Institute for Basic Biology, Okazaki, Japan
| | - Toshiaki Tameshige
- Kihara Institute for Biological Research (KIBR), Yokohama City University, Yokohama, Japan
- Division of Biological Sciences, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Eriko Betsuyaku
- Department of Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Japan
| | - Saki Hamada
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Joe Sakamoto
- Laboratory for Biothermology, National Institute for Basic Biology, Okazaki, Japan
- Biophotonics Research Group, Exploratory Research Center on Life and Living Systems (ExCELLS), Okazaki, Japan
| | - Naoyuki Uchida
- Center for Gene Research, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
| | - Keiko U. Torii
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
- Department of Molecular Biosciences and Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX, United States
| | - Kentaro K. Shimizu
- Kihara Institute for Biological Research (KIBR), Yokohama City University, Yokohama, Japan
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland
| | - Yosuke Tamada
- School of Engineering, Utsunomiya University, Utsunomiya, Japan
- Center for Optical Research and Education (CORE), Utsunomiya University, Utsunomiya, Japan
- Robotics, Engineering and Agriculture-Technology Laboratory (REAL), Utsunomiya University, Utsunomiya, Japan
| | - Hiroko Urawa
- Faculty of Education, Gifu Shotoku Gakuen University, Gifu, Japan
- Laboratory of Plant Organ Development, National Institute for Basic Biology, Okazaki, Japan
| | - Kiyotaka Okada
- Laboratory of Plant Organ Development, National Institute for Basic Biology, Okazaki, Japan
- Ryukoku Extention Center Shiga, Ryukoku University, Otsu, Japan
| | - Hiroo Fukuda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Department of Bioscience and Biotechnology, Faculty of Bioenvironmental Sciences, Kyoto University of Advanced Science, Kyoto, Japan
| | - Kiyoshi Tatematsu
- Laboratory of Plant Organ Development, National Institute for Basic Biology, Okazaki, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Yasuhiro Kamei
- Laboratory for Biothermology, National Institute for Basic Biology, Okazaki, Japan
- Robotics, Engineering and Agriculture-Technology Laboratory (REAL), Utsunomiya University, Utsunomiya, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
- Optics and Imaging Facility, Trans-Scale Biology Center, National Institute for Basic Biology, Okazaki, Japan
| | - Shigeyuki Betsuyaku
- Department of Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Japan
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4
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Fitzgerald JA, Könemann S, Krümpelmann L, Županič A, Vom Berg C. Approaches to Test the Neurotoxicity of Environmental Contaminants in the Zebrafish Model: From Behavior to Molecular Mechanisms. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:989-1006. [PMID: 33270929 DOI: 10.1002/etc.4951] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/15/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
The occurrence of neuroactive chemicals in the aquatic environment is on the rise and poses a potential threat to aquatic biota of currently unpredictable outcome. In particular, subtle changes caused by these chemicals to an organism's sensation or behavior are difficult to tackle with current test systems that focus on rodents or with in vitro test systems that omit whole-animal responses. In recent years, the zebrafish (Danio rerio) has become a popular model organism for toxicological studies and testing strategies, such as the standardized use of zebrafish early life stages in the Organisation for Economic Co-operation and Development's guideline 236. In terms of neurotoxicity, the zebrafish provides a powerful model to investigate changes to the nervous system from several different angles, offering the ability to tackle the mechanisms of action of chemicals in detail. The mechanistic understanding gained through the analysis of this model species provides a good basic knowledge of how neuroactive chemicals might interact with a teleost nervous system. Such information can help infer potential effects occurring to other species exposed to neuroactive chemicals in their aquatic environment and predicting potential risks of a chemical for the aquatic ecosystem. In the present article, we highlight approaches ranging from behavioral to structural, functional, and molecular analysis of the larval zebrafish nervous system, providing a holistic view of potential neurotoxic outcomes. Environ Toxicol Chem 2021;40:989-1006. © 2020 SETAC.
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Affiliation(s)
- Jennifer A Fitzgerald
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Sarah Könemann
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- EPF Lausanne, School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland
| | - Laura Krümpelmann
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Anže Županič
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
- National Institute of Biology, Ljubljana, Slovenia
| | - Colette Vom Berg
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
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5
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Ahmed MU, Maurya AK, Cheng L, Jorge EC, Schubert FR, Maire P, Basson MA, Ingham PW, Dietrich S. Engrailed controls epaxial-hypaxial muscle innervation and the establishment of vertebrate three-dimensional mobility. Dev Biol 2017; 430:90-104. [PMID: 28807781 DOI: 10.1016/j.ydbio.2017.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/07/2017] [Accepted: 08/08/2017] [Indexed: 11/16/2022]
Abstract
Chordates are characterised by contractile muscle on either side of the body that promotes movement by side-to-side undulation. In the lineage leading to modern jawed vertebrates (crown group gnathostomes), this system was refined: body muscle became segregated into distinct dorsal (epaxial) and ventral (hypaxial) components that are separately innervated by the medial and hypaxial motors column, respectively, via the dorsal and ventral ramus of the spinal nerves. This allows full three-dimensional mobility, which in turn was a key factor in their evolutionary success. How the new gnathostome system is established during embryogenesis and how it may have evolved in the ancestors of modern vertebrates is not known. Vertebrate Engrailed genes have a peculiar expression pattern as they temporarily demarcate a central domain of the developing musculature at the epaxial-hypaxial boundary. Moreover, they are the only genes known with this particular expression pattern. The aim of this study was to investigate whether Engrailed genes control epaxial-hypaxial muscle development and innervation. Investigating chick, mouse and zebrafish as major gnathostome model organisms, we found that the Engrailed expression domain was associated with the establishment of the epaxial-hypaxial boundary of muscle in all three species. Moreover, the outgrowing epaxial and hypaxial nerves orientated themselves with respect to this Engrailed domain. In the chicken, loss and gain of Engrailed function changed epaxial-hypaxial somite patterning. Importantly, in all animals studied, loss and gain of Engrailed function severely disrupted the pathfinding of the spinal motor axons, suggesting that Engrailed plays an evolutionarily conserved role in the separate innervation of vertebrate epaxial-hypaxial muscle.
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Affiliation(s)
- Mohi U Ahmed
- King's College London, Dept. of Craniofacial Development and Stem Cell Biology, Floor 27, Guy's Hospital Tower Wing, London SE1 9RT, UK
| | - Ashish K Maurya
- Institute of Molecular&Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Republic of Singapore
| | - Louise Cheng
- King's College London, Dept. of Craniofacial Development and Stem Cell Biology, Floor 27, Guy's Hospital Tower Wing, London SE1 9RT, UK; Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia
| | - Erika C Jorge
- King's College London, Dept. of Craniofacial Development and Stem Cell Biology, Floor 27, Guy's Hospital Tower Wing, London SE1 9RT, UK; Universidade Federal de Minas Gerais - Departamento de Morfologia, Av Antônio Carlos, 6627, Belo Horizonte, MG 31270-901, Brazil
| | - Frank R Schubert
- Institute of Biomedical and Biomolecular Science, School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Pascal Maire
- Institut Cochin, INSERM U567, CNRS UMR 8104, Univ. Paris Descartes, Département Génétique et Développement, Equipegénétique et développement du systèmeneuromusculaire, 24 Rue du Fg St Jacques, 75014 Paris, France
| | - M Albert Basson
- King's College London, Dept. of Craniofacial Development and Stem Cell Biology, Floor 27, Guy's Hospital Tower Wing, London SE1 9RT, UK
| | - Philip W Ingham
- Institute of Molecular&Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Republic of Singapore; Dept. of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore
| | - Susanne Dietrich
- King's College London, Dept. of Craniofacial Development and Stem Cell Biology, Floor 27, Guy's Hospital Tower Wing, London SE1 9RT, UK; Institute of Biomedical and Biomolecular Science, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, UK.
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6
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Slow Muscle Precursors Lay Down a Collagen XV Matrix Fingerprint to Guide Motor Axon Navigation. J Neurosci 2016; 36:2663-76. [PMID: 26937007 DOI: 10.1523/jneurosci.2847-15.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED The extracellular matrix (ECM) provides local positional information to guide motoneuron axons toward their muscle target. Collagen XV is a basement membrane component mainly expressed in skeletal muscle. We have identified two zebrafish paralogs of the human COL15A1 gene, col15a1a and col15a1b, which display distinct expression patterns. Here we show that col15a1b is expressed and deposited in the motor path ECM by slow muscle precursors also called adaxial cells. We further demonstrate that collagen XV-B deposition is both temporally and spatially regulated before motor axon extension from the spinal cord in such a way that it remains in this region after the adaxial cells have migrated toward the periphery of the myotome. Loss- and gain-of-function experiments in zebrafish embryos demonstrate that col15a1b expression and subsequent collagen XV-B deposition and organization in the motor path ECM depend on a previously undescribed two-step mechanism involving Hedgehog/Gli and unplugged/MuSK signaling pathways. In silico analysis predicts a putative Gli binding site in the col15a1b proximal promoter. Using col15a1b promoter-reporter constructs, we demonstrate that col15a1b participates in the slow muscle genetic program as a direct target of Hedgehog/Gli signaling. Loss and gain of col15a1b function provoke pathfinding errors in primary and secondary motoneuron axons both at and beyond the choice point where axon pathway selection takes place. These defects result in muscle atrophy and compromised swimming behavior, a phenotype partially rescued by injection of a smyhc1:col15a1b construct. These reveal an unexpected and novel role for collagen XV in motor axon pathfinding and neuromuscular development. SIGNIFICANCE STATEMENT In addition to the archetypal axon guidance cues, the extracellular matrix provides local information that guides motor axons from the spinal cord to their muscle targets. Many of the proteins involved are unknown. Using the zebrafish model, we identified an unexpected role of the extracellular matrix collagen XV in motor axon pathfinding. We show that the synthesis of collagen XV-B by slow muscle precursors and its deposition in the common motor path are dependent on a novel two-step mechanism that determines axon decisions at a choice point during motor axonogenesis. Zebrafish and humans use common molecular cues and regulatory mechanisms for the neuromuscular system development. And as such, our study reveals COL15A1 as a candidate gene for orphan neuromuscular disorders.
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7
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de Bruin A, A Cornelissen PW, Kirchmaier BC, Mokry M, Iich E, Nirmala E, Liang KH, D Végh AM, Scholman KT, Groot Koerkamp MJ, Holstege FC, Cuppen E, Schulte-Merker S, Bakker WJ. Genome-wide analysis reveals NRP1 as a direct HIF1α-E2F7 target in the regulation of motorneuron guidance in vivo. Nucleic Acids Res 2015; 44:3549-66. [PMID: 26681691 PMCID: PMC4856960 DOI: 10.1093/nar/gkv1471] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 12/01/2015] [Indexed: 02/03/2023] Open
Abstract
In this study, we explored the existence of a transcriptional network co-regulated by E2F7 and HIF1α, as we show that expression of E2F7, like HIF1α, is induced in hypoxia, and because of the previously reported ability of E2F7 to interact with HIF1α. Our genome-wide analysis uncovers a transcriptional network that is directly controlled by HIF1α and E2F7, and demonstrates both stimulatory and repressive functions of the HIF1α -E2F7 complex. Among this network we reveal Neuropilin 1 (NRP1) as a HIF1α-E2F7 repressed gene. By performing in vitro and in vivo reporter assays we demonstrate that the HIF1α-E2F7 mediated NRP1 repression depends on a 41 base pairs ‘E2F-binding site hub’, providing a molecular mechanism for a previously unanticipated role for HIF1α in transcriptional repression. To explore the biological significance of this regulation we performed in situ hybridizations and observed enhanced nrp1a expression in spinal motorneurons (MN) of zebrafish embryos, upon morpholino-inhibition of e2f7/8 or hif1α. Consistent with the chemo-repellent role of nrp1a, morpholino-inhibition of e2f7/8 or hif1α caused MN truncations, which was rescued in TALEN-induced nrp1ahu10012 mutants, and phenocopied in e2f7/8 mutant zebrafish. Therefore, we conclude that repression of NRP1 by the HIF1α-E2F7 complex regulates MN axon guidance in vivo.
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Affiliation(s)
- Alain de Bruin
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands Department of Pediatrics, Division of Molecular Genetics, University Medical Center Groningen, University of Groningen, Groningen 9713 AV, The Netherlands
| | - Peter W A Cornelissen
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Bettina C Kirchmaier
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands Goethe Universität Frankfurt, Buchmann Institute of Molecular Life Sciences (BMLS), Neural and Vascular Guidance group, D-60438 Frankfurt am Main, Germany
| | - Michal Mokry
- Division of Pediatrics, Wilhelmina Children's Hospital, University Medical Center Utrecht, 3508 AB Utrecht, The Netherlands
| | - Elhadi Iich
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Ella Nirmala
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Kuo-Hsuan Liang
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Anna M D Végh
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Koen T Scholman
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
| | - Marian J Groot Koerkamp
- Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, Utrecht, 3584 CG, The Netherlands
| | - Frank C Holstege
- Molecular Cancer Research, University Medical Center Utrecht, Universiteitsweg 100, Utrecht, 3584 CG, The Netherlands
| | - Edwin Cuppen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Stefan Schulte-Merker
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands Institute for Cardiovascular Organogenesis and Regeneration, Cells-in-Motion Cluster of Excellence, University of Münster, 48149 Münster, Germany
| | - Walbert J Bakker
- Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands
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8
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Kawasumi-Kita A, Hayashi T, Kobayashi T, Nagayama C, Hayashi S, Kamei Y, Morishita Y, Takeuchi T, Tamura K, Yokoyama H. Application of local gene induction by infrared laser-mediated microscope and temperature stimulator to amphibian regeneration study. Dev Growth Differ 2015; 57:601-13. [DOI: 10.1111/dgd.12241] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 09/02/2015] [Accepted: 09/03/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Aiko Kawasumi-Kita
- Department of Developmental Biology and Neurosciences; Graduate School of Life Sciences; Tohoku University; Aramaki-Aza-Aoba 6-3, Aoba-ku Sendai Miyagi 980-8578 Japan
- Laboratory for Developmental Morphogeometry; RIKEN Quantitative Biology Center; Kobe Hyogo 650-0047 Japan
| | - Toshinori Hayashi
- School of Life Science; Faculty of Medicine; Tottori University; Yonago Tottori 683-8503 Japan
| | - Takuya Kobayashi
- Department of Developmental Biology and Neurosciences; Graduate School of Life Sciences; Tohoku University; Aramaki-Aza-Aoba 6-3, Aoba-ku Sendai Miyagi 980-8578 Japan
| | - Chikashi Nagayama
- Department of Developmental Biology and Neurosciences; Graduate School of Life Sciences; Tohoku University; Aramaki-Aza-Aoba 6-3, Aoba-ku Sendai Miyagi 980-8578 Japan
| | - Shinichi Hayashi
- Department of Developmental Biology and Neurosciences; Graduate School of Life Sciences; Tohoku University; Aramaki-Aza-Aoba 6-3, Aoba-ku Sendai Miyagi 980-8578 Japan
| | - Yasuhiro Kamei
- Spectrography and Bioimaging Facility; National Institute for Basic Biology; Myodaiji Okazaki Aichi 445-8585 Japan
- Department of Basic Biology in the School of Life Science of the Graduate University for Advanced Studies (SOKENDAI); Okazaki Aichi 445-8585 Japan
| | - Yoshihiro Morishita
- Laboratory for Developmental Morphogeometry; RIKEN Quantitative Biology Center; Kobe Hyogo 650-0047 Japan
| | - Takashi Takeuchi
- School of Life Science; Faculty of Medicine; Tottori University; Yonago Tottori 683-8503 Japan
| | - Koji Tamura
- Department of Developmental Biology and Neurosciences; Graduate School of Life Sciences; Tohoku University; Aramaki-Aza-Aoba 6-3, Aoba-ku Sendai Miyagi 980-8578 Japan
| | - Hitoshi Yokoyama
- Department of Developmental Biology and Neurosciences; Graduate School of Life Sciences; Tohoku University; Aramaki-Aza-Aoba 6-3, Aoba-ku Sendai Miyagi 980-8578 Japan
- Department of Biochemistry and Molecular Biology; Faculty of Agriculture and Life Science; Hirosaki University; Hirosaki Aomori 036-8561 Japan
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9
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Balastik M, Zhou XZ, Alberich-Jorda M, Weissova R, Žiak J, Pazyra-Murphy MF, Cosker KE, Machonova O, Kozmikova I, Chen CH, Pastorino L, Asara JM, Cole A, Sutherland C, Segal RA, Lu KP. Prolyl Isomerase Pin1 Regulates Axon Guidance by Stabilizing CRMP2A Selectively in Distal Axons. Cell Rep 2015; 13:812-828. [PMID: 26489457 DOI: 10.1016/j.celrep.2015.09.026] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 07/21/2015] [Accepted: 09/08/2015] [Indexed: 12/29/2022] Open
Abstract
Axon guidance relies on precise translation of extracellular signal gradients into local changes in cytoskeletal dynamics, but the molecular mechanisms regulating dose-dependent responses of growth cones are still poorly understood. Here, we show that during embryonic development in growing axons, a low level of Semaphorin3A stimulation is buffered by the prolyl isomerase Pin1. We demonstrate that Pin1 stabilizes CDK5-phosphorylated CRMP2A, the major isoform of CRMP2 in distal axons. Consequently, Pin1 knockdown or knockout reduces CRMP2A levels specifically in distal axons and inhibits axon growth, which can be fully rescued by Pin1 or CRMP2A expression. Moreover, Pin1 knockdown or knockout increases sensitivity to Sema3A-induced growth cone collapse in vitro and in vivo, leading to developmental abnormalities in axon guidance. These results identify an important isoform-specific function and regulation of CRMP2A in controlling axon growth and uncover Pin1-catalyzed prolyl isomerization as a regulatory mechanism in axon guidance.
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Affiliation(s)
- Martin Balastik
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA; Institute of Molecular Genetics, Vídeňská 1083, 142 20 Prague 4, Czech Republic; Institute of Physiology, Vídeňská 1083, 142 20 Prague 4, Czech Republic.
| | - Xiao Zhen Zhou
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA
| | - Meritxell Alberich-Jorda
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA; Institute of Molecular Genetics, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Romana Weissova
- Institute of Molecular Genetics, Vídeňská 1083, 142 20 Prague 4, Czech Republic; Institute of Physiology, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Jakub Žiak
- Institute of Molecular Genetics, Vídeňská 1083, 142 20 Prague 4, Czech Republic; Institute of Physiology, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Maria F Pazyra-Murphy
- Department of Pediatric Oncology and Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Katharina E Cosker
- Department of Pediatric Oncology and Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Olga Machonova
- Institute of Molecular Genetics, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Iryna Kozmikova
- Institute of Molecular Genetics, Vídeňská 1083, 142 20 Prague 4, Czech Republic
| | - Chun-Hau Chen
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA
| | - Lucia Pastorino
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA
| | - John M Asara
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA
| | - Adam Cole
- Biomedical Research Institute, University of Dundee, Ninewells Hospital, Dundee DD1 9SY, Scotland, UK
| | - Calum Sutherland
- Biomedical Research Institute, University of Dundee, Ninewells Hospital, Dundee DD1 9SY, Scotland, UK
| | - Rosalind A Segal
- Department of Pediatric Oncology and Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Kun Ping Lu
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 0408, Boston, MA 02215, USA; Institute for Translational Medicine, Fujian Medical University, Fuzhou 350108, China.
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10
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Hayashi S, Ochi H, Ogino H, Kawasumi A, Kamei Y, Tamura K, Yokoyama H. Transcriptional regulators in the Hippo signaling pathway control organ growth in Xenopus tadpole tail regeneration. Dev Biol 2014; 396:31-41. [DOI: 10.1016/j.ydbio.2014.09.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/06/2014] [Accepted: 09/17/2014] [Indexed: 11/28/2022]
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11
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Moreno RL, Ribera AB. Spinal neurons require Islet1 for subtype-specific differentiation of electrical excitability. Neural Dev 2014; 9:19. [PMID: 25149090 PMCID: PMC4153448 DOI: 10.1186/1749-8104-9-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 07/16/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the spinal cord, stereotypic patterns of transcription factor expression uniquely identify neuronal subtypes. These transcription factors function combinatorially to regulate gene expression. Consequently, a single transcription factor may regulate divergent development programs by participation in different combinatorial codes. One such factor, the LIM-homeodomain transcription factor Islet1, is expressed in the vertebrate spinal cord. In mouse, chick and zebrafish, motor and sensory neurons require Islet1 for specification of biochemical and morphological signatures. Little is known, however, about the role that Islet1 might play for development of electrical membrane properties in vertebrates. Here we test for a role of Islet1 in differentiation of excitable membrane properties of zebrafish spinal neurons. RESULTS We focus our studies on the role of Islet1 in two populations of early born zebrafish spinal neurons: ventral caudal primary motor neurons (CaPs) and dorsal sensory Rohon-Beard cells (RBs). We take advantage of transgenic lines that express green fluorescent protein (GFP) to identify CaPs, RBs and several classes of interneurons for electrophysiological study. Upon knock-down of Islet1, cells occupying CaP-like and RB-like positions continue to express GFP. With respect to voltage-dependent currents, CaP-like and RB-like neurons have novel repertoires that distinguish them from control CaPs and RBs, and, in some respects, resemble those of neighboring interneurons. The action potentials fired by CaP-like and RB-like neurons also have significantly different properties compared to those elicited from control CaPs and RBs. CONCLUSIONS Overall, our findings suggest that, for both ventral motor and dorsal sensory neurons, Islet1 directs differentiation programs that ultimately specify electrical membrane as well as morphological properties that act together to sculpt neuron identity.
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Affiliation(s)
- Rosa L Moreno
- Department of Physiology, University of Colorado Anschutz Medical Campus, RC-1 North, 7403A, Mailstop 8307, 12800 E 19th Ave,, 80045 Aurora, CO, USA.
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12
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The role of inab in axon morphology of an identified zebrafish motoneuron. PLoS One 2014; 9:e88631. [PMID: 24533123 PMCID: PMC3922942 DOI: 10.1371/journal.pone.0088631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 01/15/2014] [Indexed: 12/15/2022] Open
Abstract
The ability of an animal to move and to interact with its environment requires that motoneurons correctly innervate specific muscles. Although many genes that regulate motoneuron development have been identified, our understanding of motor axon branching remains incomplete. We used transcriptional expression profiling to identify potential candidate genes involved in development of zebrafish identified motoneurons. Here we focus on inab, an intermediate filament encoding gene dynamically expressed in a subset of motoneurons as well as in an identified interneuron. We show that inab is necessary for proper axon morphology of a specific motoneuron subtype.
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13
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Morimura R, Nozawa K, Tanaka H, Ohshima T. Phosphorylation of Dpsyl2 (CRMP2) and Dpsyl3 (CRMP4) is required for positioning of caudal primary motor neurons in the zebrafish spinal cord. Dev Neurobiol 2013; 73:911-20. [DOI: 10.1002/dneu.22117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 07/23/2013] [Accepted: 07/28/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Rii Morimura
- Department of Life Science and Medical Bioscience; Waseda University; 2-2 Wakamatsu-cho, Shinjuku-ku Tokyo 162-8480 Japan
| | - Keisuke Nozawa
- Department of Life Science and Medical Bioscience; Waseda University; 2-2 Wakamatsu-cho, Shinjuku-ku Tokyo 162-8480 Japan
| | - Hideomi Tanaka
- Department of Life Science and Medical Bioscience; Waseda University; 2-2 Wakamatsu-cho, Shinjuku-ku Tokyo 162-8480 Japan
- Laboratory for Developmental Gene Regulation; RIKEN Brain Science Institute (BSI); 2-1 Hirosawa, Wako Saitama 351-0198 Japan
| | - Toshio Ohshima
- Department of Life Science and Medical Bioscience; Waseda University; 2-2 Wakamatsu-cho, Shinjuku-ku Tokyo 162-8480 Japan
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14
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Abstract
To form complex neuronal networks, growth cones use intermediate targets as guideposts on the path to more distant targets. In the developing zebrafish (Danio rerio), the muscle pioneers (MPs) are intermediate targets for primary motor neurons (PMNs) that innervate the trunk musculature. The mechanisms regulating PMN axon guidance at the MPs are not fully understood. We have identified a new member of the Notum family in zebrafish, Notum 2, which is expressed exclusively in the MPs during primary motor innervation. While homologs of Notum, including zebrafish Notum 1a, negatively regulate the Wnt/β-catenin signaling pathway, we discovered a novel function of Notum 2 in regulating motor axon guidance. Knockdown of Notum 2 resulted in a failure of caudal primary (CaP) axons to migrate beyond the MPs, despite the proper specification of the intermediate target. In contrast, mosaic Notum 2 overexpression induced branching of PMN axons. This effect is specific to Notum 2, as overexpression of Notum 1a does not affect PMN axon trajectory. Ectopic expression of Notum 2 by cells contacting the growing CaP axon induced the highest frequency of branching, suggesting that localized Notum 2 expression affects axon behavior. We propose a model where Notum 2 expression at the MPs provides a cue to release CaP motor axons from their intermediate targets, allowing growth cones to proceed to secondary targets in the ventral muscle. This work demonstrates an unexpected role for a Notum homolog in regulating growth cone migration, separate from the well established functions of other Notum homologs in Wnt signaling.
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15
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Kimura E, Deguchi T, Kamei Y, Shoji W, Yuba S, Hitomi J. Application of infrared laser to the zebrafish vascular system: gene induction, tracing, and ablation of single endothelial cells. Arterioscler Thromb Vasc Biol 2013; 33:1264-70. [PMID: 23539214 DOI: 10.1161/atvbaha.112.300602] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Infrared laser-evoked gene operator is a new microscopic method optimized to heat cells in living organisms without causing photochemical damage. By combining the promoter system for the heat shock response, infrared laser-evoked gene operator enables laser-mediated gene induction in targeted cells. We applied this method to the vascular system in zebrafish embryos and demonstrated its usability to investigate mechanisms of vascular morphogenesis in vivo. APPROACH AND RESULTS We used double-transgenic zebrafish with fli1:nEGFP to identify the endothelial cells, and with hsp:mCherry to carry out single-cell labeling. Optimizing the irradiation conditions, we finally succeeded in inducing the expression of the mCherry gene in single targeted endothelial cells, at a maximum efficiency rate of 60%. In addition, we indicated that this system could be used for laser ablation under certain conditions. To evaluate infrared laser-evoked gene operator, we applied this system to the endothelial cells of the first intersegmental arteries, and captured images of the connection between the vascular systems of the brain and spinal cord. CONCLUSIONS Our results suggest that the infrared laser-evoked gene operator system will contribute to the elucidation of the mechanisms underlying vascular morphogenesis by controlling spatiotemporal gene activation in single endothelial cells, by labeling or deleting individual vessels in living embryos.
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Affiliation(s)
- Eiji Kimura
- Department of Anatomy, Iwate Medical University, Iwate, Japan.
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16
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Plexin A3 and turnout regulate motor axonal branch morphogenesis in zebrafish. PLoS One 2013; 8:e54071. [PMID: 23349787 PMCID: PMC3549987 DOI: 10.1371/journal.pone.0054071] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/10/2012] [Indexed: 02/01/2023] Open
Abstract
During embryogenesis motor axons navigate to their target muscles, where individual motor axons develop complex branch morphologies. The mechanisms that control axonal branching morphogenesis have been studied intensively, yet it still remains unclear when branches begin to form or how branch locations are determined. Live cell imaging of individual zebrafish motor axons reveals that the first axonal branches are generated at the ventral extent of the myotome via bifurcation of the growth cone. Subsequent branches are generated by collateral branching restricted to their synaptic target field along the distal portion of the axon. This precisely timed and spatially restricted branching process is disrupted in turnout mutants we identified in a forward genetic screen. Molecular genetic mapping positioned the turnout mutation within a 300 kb region encompassing eight annotated genes, however sequence analysis of all eight open reading frames failed to unambiguously identify the turnout mutation. Chimeric analysis and single cell labeling reveal that turnout function is required cell non-autonomously for intraspinal motor axon guidance and peripheral branch formation. turnout mutant motor axons form the first branch on time via growth cone bifurcation, but unlike wild-type they form collateral branches precociously, when the growth cone is still navigating towards the ventral myotome. These precocious collateral branches emerge along the proximal region of the axon shaft typically devoid of branches, and they develop into stable, permanent branches. Furthermore, we find that null mutants of the guidance receptor plexin A3 display identical motor axon branching defects, and time lapse analysis reveals that precocious branch formation in turnout and plexin A3 mutants is due to increased stability of otherwise short-lived axonal protrusions. Thus, plexin A3 dependent intrinsic and turnout dependent extrinsic mechanisms suppress collateral branch morphogenesis by destabilizing membrane protrusions before the growth cone completes navigation into the synaptic target field.
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Liu C, Ma W, Su W, Zhang J. Prdm14 acts upstream of islet2 transcription to regulate axon growth of primary motoneurons in zebrafish. Development 2012; 139:4591-600. [PMID: 23136389 DOI: 10.1242/dev.083055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The precise formation of three-dimensional motor circuits is essential for movement control. Within these circuits, motoneurons (MNs) are specified from spinal progenitors by dorsoventral signals and distinct transcriptional programs. Different MN subpopulations have stereotypic cell body positions and show specific spatial axon trajectories. Our knowledge of MN axon outgrowth remains incomplete. Here, we report a zebrafish gene-trap mutant, short lightning (slg), in which prdm14 expression is disrupted. slg mutant embryos show shortened axons in caudal primary (CaP) MNs resulting in defective embryonic movement. Both the CaP neuronal defects and behavior abnormality of the mutants can be phenocopied by injection of a prdm14 morpholino into wild-type embryos. By removing a copy of the inserted transposon from homozygous mutants, prdm14 expression and normal embryonic movement were restored, confirming that loss of prdm14 expression accounts for the observed defects. Mechanistically, Prdm14 protein binds to the promoter region of islet2, a known transcription factor required for CaP development. Notably, disruption of islet2 function caused similar CaP axon outgrowth defects as observed in slg mutant embryos. Furthermore, overexpression of islet2 in slg mutant embryos rescued the shortened CaP axon phenotypes. Together, these data reveal that prdm14 regulates CaP axon outgrowth through activation of islet2 expression.
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Affiliation(s)
- Chao Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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18
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Zhang C, Li D, Ma Y, Yan J, Yang B, Li P, Yu A, Lu C, Ma X. Role of spastin and protrudin in neurite outgrowth. J Cell Biochem 2012; 113:2296-307. [PMID: 22573551 DOI: 10.1002/jcb.24100] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder characterized by retrograde axonal degeneration that primarily affects long spinal neurons. The gene encoding spastin has a well-established association with HSP, and protrudin is a known binding partner of spastin. Here, we demonstrate that the N-terminal domain of protrudin mediates the interaction with spastin, which is responsible for neurite outgrowth. We show that spastin promotes protrudin-dependent neurite outgrowth in PC12 cells. To further confirm these physiological functions in vivo, we microinjected zebrafish embryos with various protrudin/spastin mRNA and morpholinos. The results suggest that the spinal cord motor neuron axon outgrowth of zebrafish is regulated by the interaction between spastin and protrudin. In addition, the putative HSP-associated protrudinG191V mutation was shown to alter the subcellular distribution and impair the yolk sac extension of zebrafish, but without significant defects in neurite outgrowth both in PC12 cells and zebrafish. Taken together, our findings indicate that protrudin interacts with spastin and induces axon formation through its N-terminal domain. Moreover, protrudin and spastin may work together to play an indispensable role in motor axon outgrowth.
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Affiliation(s)
- Chuanling Zhang
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
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19
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Ccdc80-l1 Is involved in axon pathfinding of zebrafish motoneurons. PLoS One 2012; 7:e31851. [PMID: 22384085 PMCID: PMC3285184 DOI: 10.1371/journal.pone.0031851] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 01/19/2012] [Indexed: 11/29/2022] Open
Abstract
Axon pathfinding is a subfield of neural development by which neurons send out axons to reach the correct targets. In particular, motoneurons extend their axons toward skeletal muscles, leading to spontaneous motor activity. In this study, we identified the zebrafish Ccdc80 and Ccdc80-like1 (Ccdc80-l1) proteins in silico on the basis of their high aminoacidic sequence identity with the human CCDC80 (Coiled-Coil Domain Containing 80). We focused on ccdc80-l1 gene that is expressed in nervous and non-nervous tissues, in particular in territories correlated with axonal migration, such as adaxial cells and muscle pioneers. Loss of ccdc80-l1 in zebrafish embryos induced motility issues, although somitogenesis and myogenesis were not impaired. Our results strongly suggest that ccdc80-l1 is involved in axon guidance of primary and secondary motoneurons populations, but not in their proper formation. ccdc80-l1 has a differential role as regards the development of ventral and dorsal motoneurons, and this is consistent with the asymmetric distribution of the transcript. The axonal migration defects observed in ccdc80-l1 loss-of-function embryos are similar to the phenotype of several mutants with altered Hedgehog activity. Indeed, we reported that ccdc80-l1 expression is positively regulated by the Hedgehog pathway in adaxial cells and muscle pioneers. These findings strongly indicate ccdc80-l1 as a down-stream effector of the Hedgehog pathway.
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20
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Hale LA, Fowler DK, Eisen JS. Netrin signaling breaks the equivalence between two identified zebrafish motoneurons revealing a new role of intermediate targets. PLoS One 2011; 6:e25841. [PMID: 22003409 PMCID: PMC3189217 DOI: 10.1371/journal.pone.0025841] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 09/12/2011] [Indexed: 12/11/2022] Open
Abstract
Background We previously showed that equivalence between two identified zebrafish motoneurons is broken by interactions with identified muscle fibers that act as an intermediate target for the axons of these motoneurons. Here we investigate the molecular basis of the signaling interaction between the intermediate target and the motoneurons. Principal Findings We provide evidence that Netrin 1a is an intermediate target-derived signal that causes two equivalent motoneurons to adopt distinct fates. We show that although these two motoneurons express the same Netrin receptors, their axons respond differently to Netrin 1a encountered at the intermediate target. Furthermore, we demonstrate that when Netrin 1a is knocked down, more distal intermediate targets that express other Netrins can also function to break equivalence between these motoneurons. Significance Our results suggest a new role for intermediate targets in breaking neuronal equivalence. The data we present reveal that signals encountered during axon pathfinding can cause equivalent neurons to adopt distinct fates. Such signals may be key in diversifying a neuronal population and leading to correct circuit formation.
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Affiliation(s)
- Laura A. Hale
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
| | - Daniel K. Fowler
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
| | - Judith S. Eisen
- Institute of Neuroscience, University of Oregon, Eugene, Oregon, United States of America
- * E-mail:
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21
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22
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Rieger S, Wang F, Sagasti A. Time-lapse imaging of neural development: zebrafish lead the way into the fourth dimension. Genesis 2011; 49:534-45. [PMID: 21305690 DOI: 10.1002/dvg.20729] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 01/01/2023]
Abstract
Time-lapse imaging is often the only way to appreciate fully the many dynamic cell movements critical to neural development. Zebrafish possess many advantages that make them the best vertebrate model organism for live imaging of dynamic development events. This review will discuss technical considerations of time-lapse imaging experiments in zebrafish, describe selected examples of imaging studies in zebrafish that revealed new features or principles of neural development, and consider the promise and challenges of future time-lapse studies of neural development in zebrafish embryos and adults.
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Affiliation(s)
- Sandra Rieger
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, California, USA
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23
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24
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Kucenas S, Wang WD, Knapik EW, Appel B. A selective glial barrier at motor axon exit points prevents oligodendrocyte migration from the spinal cord. J Neurosci 2009; 29:15187-94. [PMID: 19955371 PMCID: PMC2837368 DOI: 10.1523/jneurosci.4193-09.2009] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 10/09/2009] [Accepted: 10/19/2009] [Indexed: 11/21/2022] Open
Abstract
Nerve roots have specialized transition zones that permit axon extension but limit cell movement between the CNS and PNS. Boundary cap cells prevent motor neuron soma from following their axons into the periphery, thereby contributing to a selective barrier. Transition zones also restrict movement of glial cells. Consequently, axons that cross the CNS-PNS interface are insulated by central and peripheral myelin. The mechanisms that prevent the migratory progenitors of oligodendrocytes and Schwann cells, the myelinating cells of the CNS and PNS, respectively, from crossing transition zones are not known. Here, we show that interactions between myelinating glial cells prevent their movements across the interface. Using in vivo time-lapse imaging in zebrafish we found that, in the absence of Schwann cells, oligodendrocyte progenitors cross ventral root transition zones and myelinate motor axons. These studies reveal that distinct mechanisms regulate the movement of axons, neurons, and glial cells across the CNS-PNS interface.
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Affiliation(s)
- Sarah Kucenas
- Department of Biological Sciences
- Vanderbilt Program in Developmental Biology, and
| | - Wen-Der Wang
- Vanderbilt Program in Developmental Biology, and
- Division of Genetic Medicine, Vanderbilt University, Nashville, Tennessee, 37235, and
| | - Ela W. Knapik
- Vanderbilt Program in Developmental Biology, and
- Division of Genetic Medicine, Vanderbilt University, Nashville, Tennessee, 37235, and
| | - Bruce Appel
- Department of Biological Sciences
- Department of Pediatrics, University of Colorado Denver–Anschutz Medical Campus, Aurora, Colorado 80045
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25
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Abstract
Multiple molecular cues guide neuronal axons to their targets during development. Previous studies in vitro have shown that mechanical stimulation also can affect axon growth; however, whether mechanical force contributes to axon guidance in vivo is unknown. We investigated the role of muscle contractions in the guidance of zebrafish peripheral Rohon-Beard (RB) sensory axons in vivo. We analyzed several mutants that affect muscle contraction through different molecular pathways, including a new mutant allele of the titin a (pik) gene, mutants that affect the hedgehog signaling pathway, and a nicotinic acetylcholine receptor mutant. We found RB axon defects in these mutants, the severity of which appeared to correlate with the extent of muscle contraction loss. These axons extend between the muscle and skin and normally have ventral trajectories and repel each other on contact. RB peripheral axons in muscle mutants extend longitudinally instead of ventrally, and the axons fail to repel one another on contact. In addition, we showed that limiting muscle movements by embedding embryos in agarose caused similar defects in peripheral RB axon guidance. This work suggests that the mechanical forces generated by muscle contractions are necessary for proper sensory axon pathfinding in vivo.
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Deguchi T, Itoh M, Urawa H, Matsumoto T, Nakayama S, Kawasaki T, Kitano T, Oda S, Mitani H, Takahashi T, Todo T, Sato J, Okada K, Hatta K, Yuba S, Kamei Y. Infrared laser-mediated local gene induction in medaka, zebrafish and Arabidopsis thaliana. Dev Growth Differ 2009; 51:769-75. [DOI: 10.1111/j.1440-169x.2009.01135.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Schmidt ER, Pasterkamp RJ, van den Berg LH. Axon guidance proteins: Novel therapeutic targets for ALS? Prog Neurobiol 2009; 88:286-301. [DOI: 10.1016/j.pneurobio.2009.05.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Revised: 04/06/2009] [Accepted: 05/27/2009] [Indexed: 12/12/2022]
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Hilario JD, Rodino-Klapac LR, Wang C, Beattie CE. Semaphorin 5A is a bifunctional axon guidance cue for axial motoneurons in vivo. Dev Biol 2008; 326:190-200. [PMID: 19059233 DOI: 10.1016/j.ydbio.2008.11.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 11/07/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
Abstract
Semaphorins are a large class of proteins that function throughout the nervous system to guide axons. It had previously been shown that Semaphorin 5A (Sema5A) was a bifunctional axon guidance cue for mammalian midbrain neurons. We found that zebrafish sema5A was expressed in myotomes during the period of motor axon outgrowth. To determine whether Sema5A functioned in motor axon guidance, we knocked down Sema5A, which resulted in two phenotypes: a delay in motor axon extension into the ventral myotome and aberrant branching of these motor axons. Both phenotypes were rescued by injection of full-length rat Sema5A mRNA. However, adding back RNA encoding the sema domain alone significantly rescued the branching phenotype in sema5A morphants. Conversely, adding back RNA encoding the thrombospondin repeat (TSR) domain alone into sema5A morphants exclusively rescued delay in ventral motor axon extension. Together, these data show that Sema5A is a bifunctional axon guidance cue for vertebrate motor axons in vivo. The TSR domain promotes growth of developing motor axons into the ventral myotome whereas the sema domain mediates repulsion and keeps these motor axons from branching into surrounding myotome regions.
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Affiliation(s)
- Jona D Hilario
- Center for Molecular Neurobiology and Department of Neuroscience, The Ohio State University, 190 Rightmire Hall, 1060 Carmack Rd, Columbus, OH 43210, USA
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Abstract
The heat shock promoter is useful for regulating transgene expression in small water-living organisms. In zebrafish embryos, downstream gene expression can be greatly induced throughout the body by raising the temperature from 28.5 degrees C to 38.0 degrees C. By manipulating the local temperature within an embryo, spatial control of transgene expression is also possible. One such way for inducing heat shock response in targeted cells is by using a laser microbeam under the microscope. In addition, random mosaic expression by transient gene expression and transplantation of the transgenic embryo into a wild type host can be considered a powerful tool for studying gene functions using this promoter. In this paper, we review the applications of the zebrafish heat shock protein promoter as a gene expression tool and for lineage labeling and transcription enhancer screening.
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Affiliation(s)
- Wataru Shoji
- Department of Cell Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
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Lesnick TG, Sorenson EJ, Ahlskog JE, Henley JR, Shehadeh L, Papapetropoulos S, Maraganore DM. Beyond Parkinson disease: amyotrophic lateral sclerosis and the axon guidance pathway. PLoS One 2008; 3:e1449. [PMID: 18197259 PMCID: PMC2175528 DOI: 10.1371/journal.pone.0001449] [Citation(s) in RCA: 49] [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: 09/13/2007] [Accepted: 12/17/2007] [Indexed: 12/11/2022] Open
Abstract
Background We recently described a genomic pathway approach to study complex diseases. We demonstrated that models constructed using single nucleotide polymorphisms (SNPs) within axon guidance pathway genes were highly predictive of Parkinson disease (PD) susceptibility, survival free of PD, and age at onset of PD within two independent whole-genome association datasets. We also demonstrated that several axon guidance pathway genes represented by SNPs within our final models were differentially expressed in PD. Methodology/Principal Findings Here we employed our genomic pathway approach to analyze data from a whole-genome association dataset of amyotrophic lateral sclerosis (ALS); and demonstrated that models constructed using SNPs within axon guidance pathway genes were highly predictive of ALS susceptibility (odds ratio = 1739.73, p = 2.92×10−60), survival free of ALS (hazards ratio = 149.80, p = 1.25×10−74), and age at onset of ALS (R2 = 0.86, p = 5.96×10−66). We also extended our analyses of a whole-genome association dataset of PD, which shared 320,202 genomic SNPs in common with the whole-genome association dataset of ALS. We compared for ALS and PD the genes represented by SNPs in the final models for susceptibility, survival free of disease, and age at onset of disease and noted that 52.2%, 37.8%, and 34.9% of the genes were shared respectively. Conclusions/Significance Our findings for the axon guidance pathway and ALS have prior biological plausibility, overlap partially with PD, and may provide important insight into the causes of these and related neurodegenerative disorders.
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Affiliation(s)
- Timothy G. Lesnick
- Division of Biostatistics, Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Eric J. Sorenson
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - J. Eric Ahlskog
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - John R. Henley
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Lina Shehadeh
- Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, Florida, United States of America
| | - Spiridon Papapetropoulos
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, Florida, United States of America
| | - Demetrius M. Maraganore
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, United States of America
- * To whom correspondence should be addressed. E-mail:
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Sato-Maeda M, Obinata M, Shoji W. Position fine-tuning of caudal primary motoneurons in the zebrafish spinal cord. Development 2008; 135:323-32. [DOI: 10.1242/dev.007559] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In zebrafish embryos, each myotome is typically innervated by three primary motoneurons (PMNs): the caudal primary (CaP), middle primary (MiP) and rostral primary (RoP). PMN axons first exit the spinal cord through a single exit point located at the midpoint of the overlying somite, which is formed beneath the CaP cell body and is pioneered by the CaP axon. However, the placement of CaP cell bodies with respect to corresponding somites is poorly understood. Here, we determined the early events in CaP cell positioning using neuropilin 1a (nrp1a):gfp transgenic embryos in which CaPs were specifically labeled with GFP. CaP cell bodies first exhibit an irregular pattern in presence of newly formed corresponding somites and then migrate to achieve their proper positions by axonogenesis stages. CaPs are generated in excess compared with the number of somites, and two CaPs often overlap at the same position through this process. Next, we showed that CaP cell bodies remain in the initial irregular positions after knockdown of Neuropilin1a, a component of the class III semaphorin receptor. Irregular CaP position frequently results in aberrant double exit points of motor axons, and secondary motor axons form aberrant exit points following CaP axons. Its expression pattern suggests that sema3ab regulates the CaP position. Indeed, irregular CaP positions and exit points are induced by Sema3ab knockdown, whose ectopic expression can alter the position of CaP cell bodies. Results suggest that Semaphorin-Neuropilin signaling plays an important role in position fine-tuning of CaP cell bodies to ensure proper exit points of motor axons.
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Affiliation(s)
- Mika Sato-Maeda
- Department of Cell Biology, Institute of Development, Aging and Cancer,Tohoku University, Sendai 980-8575, Japan
| | - Masuo Obinata
- Department of Cell Biology, Institute of Development, Aging and Cancer,Tohoku University, Sendai 980-8575, Japan
| | - Wataru Shoji
- Department of Cell Biology, Institute of Development, Aging and Cancer,Tohoku University, Sendai 980-8575, Japan
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32
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Callander DC, Lamont RE, Childs SJ, McFarlane S. Expression of multiple class three semaphorins in the retina and along the path of zebrafish retinal axons. Dev Dyn 2008; 236:2918-24. [PMID: 17879313 DOI: 10.1002/dvdy.21315] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Retinal ganglion cells (RGCs) extend axons that exit the eye, cross the midline at the optic chiasm, and synapse on target cells in the optic tectum. Class three semaphorins (Sema3s) are a family of molecules known to direct axon growth. We undertook an expression screen to identify sema3s expressed in the retina and/or brain close to in-growing RGC axons, which might therefore influence retinal-tectal pathfinding. We find that sema3Aa, 3Fa, 3Ga, and 3Gb are expressed in the retina, although only sema3Fa is present during the time window when the axons extend. Also, we show that sema3Aa and sema3E are present near or at the optic chiasm. Furthermore, sema3C, 3Fa, 3Ga, and 3Gb are expressed in regions of the diencephalon near the path taken by RGC axons. Finally, the optic tectum expresses sema3Aa, 3Fa, 3Fb, and 3Gb. Thus, sema3s are spatiotemporally placed to influence RGC axon growth.
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33
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34
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Tanaka H, Maeda R, Shoji W, Wada H, Masai I, Shiraki T, Kobayashi M, Nakayama R, Okamoto H. Novel mutations affecting axon guidance in zebrafish and a role for plexin signalling in the guidance of trigeminal and facial nerve axons. Development 2007; 134:3259-69. [PMID: 17699608 DOI: 10.1242/dev.004267] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In zebrafish embryos, the axons of the posterior trigeminal (Vp) and facial (VII) motoneurons project stereotypically to a small number of target muscles derived from the first and second branchial arches (BA1, BA2). Use of the Islet1 (Isl1)-GFP transgenic line enabled precise real-time observations of the growth cone behaviour of the Vp and VII motoneurons within BA1 and BA2. Screening for N-ethyl-N-nitrosourea-induced mutants identified seven distinct mutations affecting different steps in the axonal pathfinding of these motoneurons. The class 1 mutations caused severe defasciculation and abnormal pathfinding in both Vp and VII motor axons before they reached their target muscles in BA1. The class 2 mutations caused impaired axonal outgrowth of the Vp motoneurons at the BA1-BA2 boundary. The class 3 mutation caused impaired axonal outgrowth of the Vp motoneurons within the target muscles derived from BA1 and BA2. The class 4 mutation caused retraction of the Vp motor axons in BA1 and abnormal invasion of the VII motor axons in BA1 beyond the BA1-BA2 boundary. Time-lapse observations of the class 1 mutant, vermicelli (vmc), which has a defect in the plexin A3 (plxna3) gene, revealed that Plxna3 acts with its ligand Sema3a1 for fasciculation and correct target selection of the Vp and VII motor axons after separation from the common pathways shared with the sensory axons in BA1 and BA2, and for the proper exit and outgrowth of the axons of the primary motoneurons from the spinal cord.
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Affiliation(s)
- Hideomi Tanaka
- Laboratory for Developmental Gene Regulation, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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35
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Palaisa KA, Granato M. Analysis of zebrafish sidetracked mutants reveals a novel role for Plexin A3 in intraspinal motor axon guidance. Development 2007; 134:3251-7. [PMID: 17699603 DOI: 10.1242/dev.007112] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One of the earliest guidance decisions for spinal cord motoneurons occurs when pools of motoneurons orient their growth cones towards a common, segmental exit point. In contrast to later events, remarkably little is known about the molecular mechanisms underlying intraspinal motor axon guidance. In zebrafish sidetracked (set) mutants, motor axons exit from the spinal cord at ectopic positions. By single-cell labeling and time-lapse analysis we show that motoneurons with cell bodies adjacent to the segmental exit point properly exit from the spinal cord, whereas those farther away display pathfinding errors. Misguided growth cones either orient away from the endogenous exit point, extend towards the endogenous exit point but bypass it or exit at non-segmental, ectopic locations. Furthermore, we show that sidetracked acts cell autonomously in motoneurons. Positional cloning reveals that sidetracked encodes Plexin A3, a semaphorin guidance receptor for repulsive guidance. Finally, we show that sidetracked (plexin A3) plays an additional role in motor axonal morphogenesis. Together, our data genetically identify the first guidance receptor required for intraspinal migration of pioneering motor axons and implicate the well-described semaphorin/plexin signaling pathway in this poorly understood process. We propose that axonal repulsion via Plexin A3 is a major driving force for intraspinal motor growth cone guidance.
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Affiliation(s)
- Kelly A Palaisa
- University of Pennsylvania School of Medicine, Department of Cell and Developmental Biology, Philadelphia, PA 19104-6058, USA
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36
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Feldner J, Reimer MM, Schweitzer J, Wendik B, Meyer D, Becker T, Becker CG. PlexinA3 restricts spinal exit points and branching of trunk motor nerves in embryonic zebrafish. J Neurosci 2007; 27:4978-83. [PMID: 17475806 PMCID: PMC6672091 DOI: 10.1523/jneurosci.1132-07.2007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The pioneering primary motor axons in the zebrafish trunk are guided by multiple cues along their pathways. Plexins are receptor components for semaphorins that influence motor axon growth and path finding. We cloned plexinA3 in zebrafish and localized plexinA3 mRNA in primary motor neurons during axon outgrowth. Antisense morpholino knock-down led to substantial errors in motor axon growth. Errors comprised aberrant branching of primary motor nerves as well as additional exit points of axons from the spinal cord. Excessively branched and supernumerary nerves were found in both ventral and dorsal pathways of motor axons. The trunk environment and several other types of axons, including trigeminal axons, were not detectably affected by plexinA3 knock-down. RNA overexpression rescued all morpholino effects. Synergistic effects of combined morpholino injections indicate interactions of plexinA3 with semaphorin3A homologs. Thus, plexinA3 is a crucial receptor for axon guidance cues in primary motor neurons.
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Affiliation(s)
- Julia Feldner
- Institute for Molecular Bioscience, University of Queensland, St Lucia QLD 4072, Australia
- Zentrum für Molekulare Neurobiologie, University of Hamburg, D-20246 Hamburg, Germany
| | - Michell M. Reimer
- Centre for Neuroscience Research, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH9 1QH, United Kingdom
| | - Jörn Schweitzer
- Institut für Biologie 1, Universität Freiburg, Freiburg, D-79104, Germany
| | - Björn Wendik
- Institut für Biologie 1, Universität Freiburg, Freiburg, D-79104, Germany
| | - Dirk Meyer
- Institut für Molekularbiologie, Leopold-Franzens-Universität Innsbruck, A-6020 Innsbruck, Austria, and
| | - Thomas Becker
- Centre for Neuroscience Research, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH9 1QH, United Kingdom
- Zentrum für Molekulare Neurobiologie, University of Hamburg, D-20246 Hamburg, Germany
| | - Catherina G. Becker
- Centre for Neuroscience Research, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH9 1QH, United Kingdom
- Zentrum für Molekulare Neurobiologie, University of Hamburg, D-20246 Hamburg, Germany
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