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Lu C, Lv Y, Meng X, Yang T, Liu Y, Kou G, Yang X, Luo J. The potential toxic effects of estrogen exposure on neural and vascular development in zebrafish. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 283:116862. [PMID: 39128450 DOI: 10.1016/j.ecoenv.2024.116862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 08/01/2024] [Accepted: 08/08/2024] [Indexed: 08/13/2024]
Abstract
Estrogens and estrogenic chemicals are endocrine-disrupting chemicals (EDCs). The potential toxicity of EDCs to humans and aquatic organisms has become increasingly concerning. However, at present, the potential toxic mechanisms of EDCs on neural and vascular development are still being fully investigated. During the study, we utilized zebrafish to assess the developmental neural and vascular toxicity of different estrogens. The results indicated that zebrafish treated with different estrogens, especially E2, exhibit developmental malformations, including increased mortality, decreased body length, decreased heart rate, aberrant swimming behavior, and increased developmental malformations, including spinal curvature (SC), yolk edema (YE) and pericaidial edema (PE), in a dose-dependent manner with 72 h-treated. Further morphological evaluation revealed that E2 exposure significantly induced motor neural abnormalities in zebrafish embryos. In addition, treated with these three estrogens also impaired the vascular development in the early stage of zebrafish embryos. Mechanistically, the identification of downstream factors revealed that several key neural and vascular development-related genes, including syn2a, gfap, gap43, shha, kdr, flt1 and flt4, were transcriptionally downregulated after estrogen exposure in zebrafish, suggesting that estrogen exposure might cause neural and vascular toxicity by interfering the mRNA levels of genes relevant to neural and vascular development.
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Affiliation(s)
- Chunjiao Lu
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China
| | - Yuhang Lv
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China
| | - Xin Meng
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China
| | - Ting Yang
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China
| | - Yi Liu
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China
| | - Guanhua Kou
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China
| | - Xiaojun Yang
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China; Department of Neurosurgery, The First Affiliated Hospital of Shantou University Medical College, Shantou, China.
| | - Juanjuan Luo
- Engineering Research Center of Key Technique for Biotherapy of Guangdong Province, Shantou University Medical College, Shantou 515041, China.
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2
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Dumoulin A, Wilson NH, Tucker KL, Stoeckli ET. A cell-autonomous role for primary cilium-mediated signaling in long-range commissural axon guidance. Development 2024; 151:dev202788. [PMID: 39157903 DOI: 10.1242/dev.202788] [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: 02/23/2024] [Accepted: 08/08/2024] [Indexed: 08/20/2024]
Abstract
Ciliopathies are characterized by the absence or dysfunction of primary cilia. Despite the fact that cognitive impairments are a common feature of ciliopathies, how cilia dysfunction affects neuronal development has not been characterized in detail. Here, we show that primary cilium-mediated signaling is required cell-autonomously by neurons during neural circuit formation. In particular, a functional primary cilium is crucial during axonal pathfinding for the switch in responsiveness of axons at a choice point or intermediate target. Using different animal models and in vivo, ex vivo and in vitro experiments, we provide evidence for a crucial role of primary cilium-mediated signaling in long-range axon guidance. The primary cilium on the cell body of commissural neurons transduces long-range guidance signals sensed by growth cones navigating an intermediate target. In extension of our finding that Shh is required for the rostral turn of post-crossing commissural axons, we suggest a model implicating the primary cilium in Shh signaling upstream of a transcriptional change of axon guidance receptors, which in turn mediate the repulsive response to floorplate-derived Shh shown by post-crossing commissural axons.
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Affiliation(s)
- Alexandre Dumoulin
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Nicole H Wilson
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Kerry L Tucker
- University of New England, College of Osteopathic Medicine, Department of Biomedical Sciences, Center for Excellence in the Neurosciences, Biddeford, ME 04005, USA
| | - Esther T Stoeckli
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- University Research Priority Program 'Adaptive Brain Circuits in Development and Learning' (URPP AdaBD), University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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3
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Liu J, Wang Y, Liu X, Han J, Tian Y. Spatiotemporal changes in Netrin/Dscam1 signaling dictate axonal projection direction in Drosophila small ventral lateral clock neurons. eLife 2024; 13:RP96041. [PMID: 39052321 PMCID: PMC11272162 DOI: 10.7554/elife.96041] [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] [Indexed: 07/27/2024] Open
Abstract
Axon projection is a spatial- and temporal-specific process in which the growth cone receives environmental signals guiding axons to their final destination. However, the mechanisms underlying changes in axonal projection direction without well-defined landmarks remain elusive. Here, we present evidence showcasing the dynamic nature of axonal projections in Drosophila's small ventral lateral clock neurons (s-LNvs). Our findings reveal that these axons undergo an initial vertical projection in the early larval stage, followed by a subsequent transition to a horizontal projection in the early-to-mid third instar larvae. The vertical projection of s-LNv axons correlates with mushroom body calyx expansion, while the s-LNv-expressed Down syndrome cell adhesion molecule (Dscam1) interacts with Netrins to regulate the horizontal projection. During a specific temporal window, locally newborn dorsal clock neurons secrete Netrins, facilitating the transition of axonal projection direction in s-LNvs. Our study establishes a compelling in vivo model to probe the mechanisms of axonal projection direction switching in the absence of clear landmarks. These findings underscore the significance of dynamic local microenvironments in the complementary regulation of axonal projection direction transitions.
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Affiliation(s)
- Jingjing Liu
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast UniversityNanjingChina
| | - Yuedong Wang
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast UniversityNanjingChina
| | - Xian Liu
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast UniversityNanjingChina
| | - Junhai Han
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast UniversityNanjingChina
- Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
| | - Yao Tian
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast UniversityNanjingChina
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4
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Sauvé R, Morin S, Yam PT, Charron F. β-arrestins Are Scaffolding Proteins Required for Shh-Mediated Axon Guidance. J Neurosci 2024; 44:e0261242024. [PMID: 38886055 PMCID: PMC11270522 DOI: 10.1523/jneurosci.0261-24.2024] [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: 02/08/2024] [Revised: 05/31/2024] [Accepted: 06/06/2024] [Indexed: 06/20/2024] Open
Abstract
During nervous system development, Sonic hedgehog (Shh) guides developing commissural axons toward the floor plate of the spinal cord. To guide axons, Shh binds to its receptor Boc and activates downstream effectors such as Smoothened (Smo) and Src family kinases (SFKs). SFK activation requires Smo activity and is also required for Shh-mediated axon guidance. Here we report that β-arrestin1 and β-arrestin2 (β-arrestins) serve as scaffolding proteins that link Smo and SFKs in Shh-mediated axon guidance. We found that β-arrestins are expressed in rat commissural neurons. We also found that Smo, β-arrestins, and SFKs form a tripartite complex, with the complex formation dependent on β-arrestins. β-arrestin knockdown blocked the Shh-mediated increase in Src phosphorylation, demonstrating that β-arrestins are required to activate Src kinase downstream of Shh. β-arrestin knockdown also led to the loss of Shh-mediated attraction of rat commissural axons in axon turning assays. Expression of two different dominant-negative β-arrestins, β-arrestin1 V53D which blocks the internalization of Smo and β-arrestin1 P91G-P121E which blocks its interaction with SFKs, also led to the loss of Shh-mediated attraction of commissural axons. In vivo, the expression of these dominant-negative β-arrestins caused defects in commissural axon guidance in the spinal cord of chick embryos of mixed sexes. Thus we show that β-arrestins are essential scaffolding proteins that connect Smo to SFKs and are required for Shh-mediated axon guidance.
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Affiliation(s)
- Rachelle Sauvé
- Montreal Clinical Research Institute (IRCM), Montreal, Quebec H2W 1R7, Canada
- Department of Medicine, University of Montreal, Montreal, Quebec H3T 1J4, Canada
| | - Steves Morin
- Montreal Clinical Research Institute (IRCM), Montreal, Quebec H2W 1R7, Canada
| | - Patricia T Yam
- Montreal Clinical Research Institute (IRCM), Montreal, Quebec H2W 1R7, Canada
| | - Frédéric Charron
- Montreal Clinical Research Institute (IRCM), Montreal, Quebec H2W 1R7, Canada
- Department of Medicine, University of Montreal, Montreal, Quebec H3T 1J4, Canada
- Division of Experimental Medicine, Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0G4, Canada
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5
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Albano GA, Hackam AS. Repurposing development genes for axonal regeneration following injury: Examining the roles of Wnt signaling. Front Cell Dev Biol 2024; 12:1417928. [PMID: 38882059 PMCID: PMC11176474 DOI: 10.3389/fcell.2024.1417928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/13/2024] [Indexed: 06/18/2024] Open
Abstract
In this review, we explore the connections between developmental embryology and axonal regeneration. Genes that regulate embryogenesis and central nervous system (CNS) development are discussed for their therapeutic potential to induce axonal and cellular regeneration in adult tissues after neuronal injury. Despite substantial differences in the tissue environment in the developing CNS compared with the injured CNS, recent studies have identified multiple molecular pathways that promote axonal growth in both scenarios. We describe various molecular cues and signaling pathways involved in neural development, with an emphasis on the versatile Wnt signaling pathway. We discuss the capacity of developmental factors to initiate axonal regrowth in adult neural tissue within the challenging environment of the injured CNS. Our discussion explores the roles of Wnt signaling and also examines the potential of other embryonic genes including Pax, BMP, Ephrin, SOX, CNTF, PTEN, mTOR and STAT3 to contribute to axonal regeneration in various CNS injury model systems, including spinal cord and optic crush injuries in mice, Xenopus and zebrafish. Additionally, we describe potential contributions of Müller glia redifferentiation to neuronal regeneration after injury. Therefore, this review provides a comprehensive summary of the state of the field, and highlights promising research directions for the potential therapeutic applications of specific embryologic molecular pathways in axonal regeneration in adults.
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Affiliation(s)
- Gabrielle A Albano
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Abigail S Hackam
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
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6
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Masuda A, Nishida K, Ajima R, Saga Y, Bakhtan M, Klar A, Hirata T, Zhu Y. A global gene regulatory program and its region-specific regulator partition neurons into commissural and ipsilateral projection types. SCIENCE ADVANCES 2024; 10:eadk2149. [PMID: 38781326 PMCID: PMC11114196 DOI: 10.1126/sciadv.adk2149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 04/16/2024] [Indexed: 05/25/2024]
Abstract
Understanding the genetic programs that drive neuronal diversification into classes and subclasses is key to understand nervous system development. All neurons can be classified into two types: commissural and ipsilateral, based on whether their axons cross the midline or not. However, the gene regulatory program underlying this binary division is poorly understood. We identified a pair of basic helix-loop-helix transcription factors, Nhlh1 and Nhlh2, as a global transcriptional mechanism that controls the laterality of all floor plate-crossing commissural axons in mice. Mechanistically, Nhlh1/2 play an essential role in the expression of Robo3, the key guidance molecule for commissural axon projections. This genetic program appears to be evolutionarily conserved in chick. We further discovered that Isl1, primarily expressed in ipsilateral neurons within neural tubes, negatively regulates the Robo3 induction by Nhlh1/2. Our findings elucidate a gene regulatory strategy where a conserved global mechanism intersects with neuron class-specific regulators to control the partitioning of neurons based on axon laterality.
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Affiliation(s)
- Aki Masuda
- National Institute of Genetics, Graduate University for Advanced Studies, Sokendai, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Kazuhiko Nishida
- Department of Medical Chemistry, Kansai Medical University, Hirakata, Osaka 573-1010, Japan
| | - Rieko Ajima
- National Institute of Genetics, Graduate University for Advanced Studies, Sokendai, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Yumiko Saga
- National Institute of Genetics, Graduate University for Advanced Studies, Sokendai, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Marah Bakhtan
- Department of Medical Neurobiology, IMRIC, Hebrew University - Hadassah Medical School, Jerusalem, Israel
| | - Avihu Klar
- Department of Medical Neurobiology, IMRIC, Hebrew University - Hadassah Medical School, Jerusalem, Israel
| | - Tatsumi Hirata
- National Institute of Genetics, Graduate University for Advanced Studies, Sokendai, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Yan Zhu
- National Institute of Genetics, Graduate University for Advanced Studies, Sokendai, Yata 1111, Mishima, Shizuoka 411-8540, Japan
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7
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Safronov BV, Szucs P. Novel aspects of signal processing in lamina I. Neuropharmacology 2024; 247:109858. [PMID: 38286189 DOI: 10.1016/j.neuropharm.2024.109858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 01/31/2024]
Abstract
The most superficial layer of the spinal dorsal horn, lamina I, is a key element of the nociceptive processing system. It contains different types of projection neurons (PNs) and local-circuit neurons (LCNs) whose functional roles in the signal processing are poorly understood. This article reviews recent progress in elucidating novel anatomical features and physiological properties of lamina I PNs and LCNs revealed by whole-cell recordings in ex vivo spinal cord. This article is part of the Special Issue on "Ukrainian Neuroscience".
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Affiliation(s)
- Boris V Safronov
- Neuronal Networks Group, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
| | - Peter Szucs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary; HUN-REN-DE Neuroscience Research Group, Debrecen, Hungary
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8
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Wu B, Yang L, Xi C, Yao H, Chen L, Fan F, Wu G, Du Z, Hu J, Hu S. Corticospinal-specific Shh overexpression in combination with rehabilitation promotes CST axonal sprouting and skilled motor functional recovery after ischemic stroke. Mol Neurobiol 2024; 61:2186-2196. [PMID: 37864058 DOI: 10.1007/s12035-023-03642-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 09/06/2023] [Indexed: 10/22/2023]
Abstract
Ischemic stroke often leads to permanent neurological impairments, largely due to limited neuroplasticity in adult central nervous system. Here, we first showed that the expression of Sonic Hedgehog (Shh) in corticospinal neurons (CSNs) peaked at the 2nd postnatal week, when corticospinal synaptogenesis occurs. Overexpression of Shh in adult CSNs did not affect motor functions and had borderline effects on promoting the recovery of skilled locomotion following ischemic stroke. In contrast, CSNs-specific Shh overexpression significantly enhanced the efficacy of rehabilitative training, resulting in robust axonal sprouting and synaptogenesis of corticospinal axons into the denervated spinal cord, along with significantly improved behavioral outcomes. Mechanistically, combinatory treatment led to additional mTOR activation in CSNs when compared to that evoked by rehabilitative training alone. Taken together, our study unveiled a role of Shh, a morphogen involved in early development, in enhancing neuroplasticity, which significantly improved the outcomes of rehabilitative training. These results thus provide novel insights into the design of combinatory treatment for stroke and traumatic central nervous system injuries.
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Affiliation(s)
- Biwu Wu
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Lei Yang
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Caihua Xi
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Haijun Yao
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Long Chen
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Fengqi Fan
- Pain Department of Yueyang Integrated Traditional Chinese and Western Medicine Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Gang Wu
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Zhouying Du
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Jin Hu
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China
- National Center for Neurological Disorders, Shanghai, China
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China
- Neurosurgical Institute of Fudan University, Shanghai, China
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China
| | - Shukun Hu
- Department of Neurosurgery and Neurocritical Care, Affiliated Huashan Hospital, Fudan University, 12 Wulumuqi Middle Road, Shanghai, 200042, China.
- National Center for Neurological Disorders, Shanghai, China.
- Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China.
- Neurosurgical Institute of Fudan University, Shanghai, China.
- Shanghai Clinical Medical Center of Neurosurgery, Shanghai, China.
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9
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Cucun G, Köhler M, Pfitsch S, Rastegar S. Insights into the mechanisms of neuron generation and specification in the zebrafish ventral spinal cord. FEBS J 2024; 291:646-662. [PMID: 37498183 DOI: 10.1111/febs.16913] [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: 05/02/2023] [Revised: 06/20/2023] [Accepted: 07/25/2023] [Indexed: 07/28/2023]
Abstract
The vertebrate nervous system is composed of a wide range of neurons and complex synaptic connections, raising the intriguing question of how neuronal diversity is generated. The spinal cord provides an excellent model for exploring the mechanisms governing neuronal diversity due to its simple neural network and the conserved molecular processes involved in neuron formation and specification during evolution. This review specifically examines two distinct progenitor domains present in the zebrafish ventral spinal cord: the lateral floor plate (LFP) and the p2 progenitor domain. The LFP is responsible for the production of GABAergic Kolmer-Agduhr neurons (KA″), glutamatergic V3 neurons, and intraspinal serotonergic neurons, while the p2 domain generates V2 precursors that subsequently differentiate into three unique subpopulations of V2 neurons, namely glutamatergic V2a, GABAergic V2b, and glycinergic V2s. Based on recent findings, we will examine the fundamental signaling pathways and transcription factors that play a key role in the specification of these diverse neurons and neuronal subtypes derived from the LFP and p2 progenitor domains.
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Affiliation(s)
- Gokhan Cucun
- Institute for Biological and Chemical Systems - Biological Information Processing (IBCS-BIP), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Melina Köhler
- Institute for Biological and Chemical Systems - Biological Information Processing (IBCS-BIP), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Sabrina Pfitsch
- Institute for Biological and Chemical Systems - Biological Information Processing (IBCS-BIP), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Sepand Rastegar
- Institute for Biological and Chemical Systems - Biological Information Processing (IBCS-BIP), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
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10
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Cai E, Barba MG, Ge X. Hedgehog Signaling in Cortical Development. Cells 2023; 13:21. [PMID: 38201225 PMCID: PMC10778342 DOI: 10.3390/cells13010021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024] Open
Abstract
The Hedgehog (Hh) pathway plays a crucial role in embryonic development, acting both as a morphogenic signal that organizes tissue formation and a potent mitogenic signal driving cell proliferation. Dysregulated Hh signaling leads to various developmental defects in the brain. This article aims to review the roles of Hh signaling in the development of the neocortex in the mammalian brain, focusing on its regulation of neural progenitor proliferation and neuronal production. The review will summarize studies on genetic mouse models that have targeted different components of the Hh pathway, such as the ligand Shh, the receptor Ptch1, the GPCR-like transducer Smo, the intracellular transducer Sufu, and the three Gli transcription factors. As key insights into the Hh signaling transduction mechanism were obtained from mouse models displaying neural tube defects, this review will also cover some studies on Hh signaling in neural tube development. The results from these genetic mouse models suggest an intriguing hypothesis that elevated Hh signaling may play a role in the gyrification of the brain in certain species. Additionally, the distinctive production of GABAergic interneurons in the dorsal cortex in the human brain may also be linked to the extension of Hh signaling from the ventral to the dorsal brain region. Overall, these results suggest key roles of Hh signaling as both a morphogenic and mitogenic signal during the forebrain development and imply the potential involvement of Hh signaling in the evolutionary expansion of the neocortex.
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Affiliation(s)
| | | | - Xuecai Ge
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California Merced, Merced, CA 95340, USA
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11
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Deshpande G, Ng C, Jourjine N, Chiew JW, Dasilva J, Schedl P. Hedgehog signaling guides migration of primordial germ cells to the Drosophila somatic gonad. Genetics 2023; 225:iyad165. [PMID: 37708366 PMCID: PMC10627259 DOI: 10.1093/genetics/iyad165] [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: 07/25/2023] [Revised: 08/18/2023] [Accepted: 08/21/2023] [Indexed: 09/16/2023] Open
Abstract
In addition to inducing nonautonomous specification of cell fate in both Drosophila and vertebrates, the Hedgehog pathway guides cell migration in a variety of different tissues. Although its role in axon guidance in the vertebrate nervous system is widely recognized, its role in guiding the migratory path of primordial germ cells (PGCs) from the outside surface of the Drosophila embryo through the midgut and mesoderm to the SGPs (somatic gonadal precursors) has been controversial. Here we present new experiments demonstrating (1) that Hh produced by mesodermal cells guides PGC migration, (2) that HMG CoenzymeA reductase (Hmgcr) potentiates guidance signals emanating from the SGPs, functioning upstream of hh and of 2 Hh pathway genes important for Hh-containing cytonemes, and (3) that factors required in Hh receiving cells in other contexts function in PGCs to help direct migration toward the SGPs. We also compare the data reported by 4 different laboratories that have studied the role of the Hh pathway in guiding PGC migration.
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Affiliation(s)
- Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Chris Ng
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Nicholas Jourjine
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Joy Wan Chiew
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Juliana Dasilva
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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12
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Rapti G. Regulation of axon pathfinding by astroglia across genetic model organisms. Front Cell Neurosci 2023; 17:1241957. [PMID: 37941606 PMCID: PMC10628440 DOI: 10.3389/fncel.2023.1241957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 09/07/2023] [Indexed: 11/10/2023] Open
Abstract
Glia and neurons are intimately associated throughout bilaterian nervous systems, and were early proposed to interact for patterning circuit assembly. The investigations of circuit formation progressed from early hypotheses of intermediate guideposts and a "glia blueprint", to recent genetic and cell manipulations, and visualizations in vivo. An array of molecular factors are implicated in axon pathfinding but their number appears small relatively to circuit complexity. Comprehending this circuit complexity requires to identify unknown factors and dissect molecular topographies. Glia contribute to both aspects and certain studies provide molecular and functional insights into these contributions. Here, I survey glial roles in guiding axon navigation in vivo, emphasizing analogies, differences and open questions across major genetic models. I highlight studies pioneering the topic, and dissect recent findings that further advance our current molecular understanding. Circuits of the vertebrate forebrain, visual system and neural tube in zebrafish, mouse and chick, the Drosophila ventral cord and the C. elegans brain-like neuropil emerge as major contexts to study glial cell functions in axon navigation. I present astroglial cell types in these models, and their molecular and cellular interactions that drive axon guidance. I underline shared principles across models, conceptual or technical complications, and open questions that await investigation. Glia of the radial-astrocyte lineage, emerge as regulators of axon pathfinding, often employing common molecular factors across models. Yet this survey also highlights different involvements of glia in embryonic navigation or pioneer axon pathfinding, and unknowns in the molecular underpinnings of glial cell functions. Future cellular and molecular investigations should complete the comprehensive view of glial roles in circuit assembly.
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Affiliation(s)
- Georgia Rapti
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Epigenetics and Neurobiology Unit, European Molecular Biology Laboratory, Rome, Italy
- Interdisciplinary Center of Neurosciences, Heidelberg University, Heidelberg, Germany
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13
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Sullivan KG, Bashaw GJ. Commissureless acts as a substrate adapter in a conserved Nedd4 E3 ubiquitin ligase pathway to promote axon growth across the midline. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.13.562283. [PMID: 37905056 PMCID: PMC10614773 DOI: 10.1101/2023.10.13.562283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
In both vertebrates and invertebrates, commissural neurons prevent premature responsiveness to the midline repellant Slit by downregulating surface levels of its receptor Roundabout1 (Robo1). In Drosophila, Commissureless (Comm) plays a critical role in this process; however, there is conflicting data on the underlying molecular mechanism. Here, we demonstrate that the conserved PY motifs in the cytoplasmic domain of Comm are required allow the ubiquitination and lysosomal degradation of Robo1. Disruption of these motifs prevents Comm from localizing to Lamp1 positive late endosomes and to promote axon growth across the midline in vivo. In addition, we conclusively demonstrate a role for Nedd4 in midline crossing. Genetic analysis shows that nedd4 mutations result in midline crossing defects in the Drosophila embryonic nerve cord, which can be rescued by introduction of exogenous Nedd4. Biochemical evidence shows that Nedd4 incorporates into a three-member complex with Comm and Robo in a PY motif-dependent manner. Finally, we present genetic evidence that Nedd4 acts with Comm in the embryonic nerve cord to downregulate Robo1 levels. Taken together, these findings demonstrate that Comm promotes midline crossing in the nerve cord by facilitating Robo ubiquitination by Nedd4, ultimately leading to its degradation.
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Affiliation(s)
- Kelly G. Sullivan
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd., Philadelphia, PA, 19104, USA
| | - Greg J. Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd., Philadelphia, PA, 19104, USA
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14
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Herrera A, Menendez A, Ochoa A, Bardia L, Colombelli J, Pons S. Neurogenesis redirects β-catenin from adherens junctions to the nucleus to promote axonal growth. Development 2023; 150:dev201651. [PMID: 37519286 PMCID: PMC10482005 DOI: 10.1242/dev.201651] [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: 01/27/2023] [Accepted: 07/26/2023] [Indexed: 08/01/2023]
Abstract
Here, we show that, in the developing spinal cord, after the early Wnt-mediated Tcf transcription activation that confers dorsal identity to neural stem cells, neurogenesis redirects β-catenin from the adherens junctions to the nucleus to stimulate Tcf-dependent transcription in a Wnt-independent manner. This new β-catenin activity regulates genes implicated in several aspects of contralateral axon growth, including axon guidance and adhesion. Using live imaging of ex-vivo chick neural tube, we showed that the nuclear accumulation of β-catenin and the rise in Tcf-dependent transcription both initiate before the dismantling of the adherens junctions and remain during the axon elongation process. Notably, we demonstrated that β-catenin activity in post-mitotic cells depends on TCF7L2 and is central to spinal commissural axon growth. Together, our results reveal Wnt-independent Tcf/β-catenin regulation of genes that control the growth and guidance of commissural axons in chick spinal cord.
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Affiliation(s)
- Antonio Herrera
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Anghara Menendez
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Andrea Ochoa
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Lídia Bardia
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, Barcelona 08028, Spain
| | - Julien Colombelli
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, Barcelona 08028, Spain
| | - Sebastian Pons
- Instituto de Biología Molecular de Barcelona (IBMB-CSIC), Parc Científic de Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain
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15
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Dailey-Krempel B, Martin AL, Jo HN, Junge HJ, Chen Z. A tug of war between DCC and ROBO1 signaling during commissural axon guidance. Cell Rep 2023; 42:112455. [PMID: 37149867 DOI: 10.1016/j.celrep.2023.112455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/07/2023] [Accepted: 04/14/2023] [Indexed: 05/09/2023] Open
Abstract
Dynamic and coordinated axonal responses to changing environments are critical for establishing neural connections. As commissural axons migrate across the CNS midline, they are suggested to switch from being attracted to being repelled in order to approach and to subsequently leave the midline. A molecular mechanism that is hypothesized to underlie this switch in axonal responses is the silencing of Netrin1/Deleted in Colorectal Carcinoma (DCC)-mediated attraction by the repulsive SLIT/ROBO1 signaling. Using in vivo approaches including CRISPR-Cas9-engineered mouse models of distinct Dcc splice isoforms, we show here that commissural axons maintain responsiveness to both Netrin and SLIT during midline crossing, although likely at quantitatively different levels. In addition, full-length DCC in collaboration with ROBO3 can antagonize ROBO1 repulsion in vivo. We propose that commissural axons integrate and balance the opposing DCC and Roundabout (ROBO) signaling to ensure proper guidance decisions during midline entry and exit.
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Affiliation(s)
| | - Andrew L Martin
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ha-Neul Jo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Harald J Junge
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA
| | - Zhe Chen
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
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16
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Gu J, Guo L, Zhu Y, Qian L, Shi L, Zhang H, Ji G. Neurodevelopmental Toxicity of Emamectin Benzoate to the Early Life Stage of Zebrafish Larvae ( Danio rerio). Int J Mol Sci 2023; 24:ijms24043757. [PMID: 36835165 PMCID: PMC9964762 DOI: 10.3390/ijms24043757] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/02/2023] [Accepted: 02/06/2023] [Indexed: 02/16/2023] Open
Abstract
Emamectin benzoate (EMB) is a widely used pesticide and feed additive in agriculture and aquaculture. It easily enters the aquatic environment through various pathways, thus causing adverse effects on aquatic organisms. However, there are no systematic studies regarding the effects of EMB on the developmental neurotoxicity of aquatic organisms. Therefore, the aim of this study was to evaluate the neurotoxic effects and mechanisms of EMB at different concentrations (0.1, 0.25, 0.5, 1, 2, 4 and 8 μg/mL) using zebrafish as a model. The results showed that EMB significantly inhibited the hatching rate, spontaneous movement, body length, and swim bladder development of zebrafish embryos, as well as significantly increased the malformation rate of zebrafish larvae. In addition, EMB adversely affected the axon length of motor neurons in Tg (hb9: eGFP) zebrafish and central nervous system (CNS) neurons in Tg (HuC: eGFP) zebrafish and significantly inhibited the locomotor behavior of zebrafish larvae. Meanwhile, EMB induced oxidative damage and was accompanied by increasing reactive oxygen species in the brains of zebrafish larvae. In addition, gene expression involvement in oxidative stress-related (cat, sod and Cu/Zn-sod), GABA neural pathway-related (gat1, gabra1, gad1b, abat and glsa), neurodevelopmental-related (syn2a, gfap, elavl3, shha, gap43 and Nrd) and swim bladder development-related (foxa3, pbxla, mnx1, has2 and elovlla) genes was significantly affected by EMB exposure. In conclusion, our study shows that exposure to EMB during the early life stages of zebrafish significantly increases oxidative damage and inhibits early central neuronal development, motor neuron axon growth and swim bladder development, ultimately leading to neurobehavioral changes in juvenile zebrafish.
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Affiliation(s)
- Jie Gu
- Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
| | - Liguo Guo
- Innovation Center for Sustainable Forestry in Southen China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
| | - Yuanhui Zhu
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Toxicology, School of Public Health, Medical College of Soochow University, Suzhou 215123, China
| | - Lingling Qian
- Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
| | - Lili Shi
- Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
| | - Huanchao Zhang
- Innovation Center for Sustainable Forestry in Southen China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
- Correspondence: (H.Z.); (G.J.)
| | - Guixiang Ji
- Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China
- Correspondence: (H.Z.); (G.J.)
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17
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Douceau S, Deutsch Guerrero T, Ferent J. Establishing Hedgehog Gradients during Neural Development. Cells 2023; 12:225. [PMID: 36672161 PMCID: PMC9856818 DOI: 10.3390/cells12020225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/23/2022] [Accepted: 12/25/2022] [Indexed: 01/07/2023] Open
Abstract
A morphogen is a signaling molecule that induces specific cellular responses depending on its local concentration. The concept of morphogenic gradients has been a central paradigm of developmental biology for decades. Sonic Hedgehog (Shh) is one of the most important morphogens that displays pleiotropic functions during embryonic development, ranging from neuronal patterning to axon guidance. It is commonly accepted that Shh is distributed in a gradient in several tissues from different origins during development; however, how these gradients are formed and maintained at the cellular and molecular levels is still the center of a great deal of research. In this review, we first explored all of the different sources of Shh during the development of the nervous system. Then, we detailed how these sources can distribute Shh in the surrounding tissues via a variety of mechanisms. Finally, we addressed how disrupting Shh distribution and gradients can induce severe neurodevelopmental disorders and cancers. Although the concept of gradient has been central in the field of neurodevelopment since the fifties, we also describe how contemporary leading-edge techniques, such as organoids, can revisit this classical model.
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Affiliation(s)
- Sara Douceau
- INSERM UMR-S 1270, F-75005 Paris, France
- Institut du Fer à Moulin, INSERM, Sorbonne Univeristy, F-75005 Paris, France
| | - Tanya Deutsch Guerrero
- INSERM UMR-S 1270, F-75005 Paris, France
- Institut du Fer à Moulin, INSERM, Sorbonne Univeristy, F-75005 Paris, France
| | - Julien Ferent
- INSERM UMR-S 1270, F-75005 Paris, France
- Institut du Fer à Moulin, INSERM, Sorbonne Univeristy, F-75005 Paris, France
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18
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Sullivan KG, Bashaw GJ. Intracellular Trafficking Mechanisms that Regulate Repulsive Axon Guidance. Neuroscience 2023; 508:123-136. [PMID: 35863679 PMCID: PMC9839465 DOI: 10.1016/j.neuroscience.2022.07.012] [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: 03/31/2022] [Revised: 07/01/2022] [Accepted: 07/13/2022] [Indexed: 01/17/2023]
Abstract
Friedrich Bonhoeffer made seminal contributions to the study of axon guidance in the developing nervous system. His discoveries of key cellular and molecular mechanisms that dictate wiring specificity laid the foundation for countless investigators who have followed in his footsteps. Perhaps his most significant contribution was the cloning and characterization of members of the conserved ephrin family of repulsive axon guidance cues. In this review, we highlight the major contributions that Bonhoeffer and his colleagues made to the field of axon guidance, and discuss ongoing investigations into the diverse array of mechanisms that ensure that axon repulsion is precisely regulated to allow for accurate pathfinding. Specifically, we focus our discussion on the post-translational regulation of two major families of repulsive axon guidance factors: ephrin ligands and their Eph receptors, and slit ligands and their Roundabout (Robo) receptors. We will give special emphasis to the ways in which regulated endocytic trafficking events allow navigating axons to adjust their responses to repellant signals and how these trafficking events are intimately related to receptor signaling. By highlighting parallels and differences between the regulation of these two important repulsive axon guidance pathways, we hope to identify key outstanding questions for future investigation.
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Affiliation(s)
- Kelly G Sullivan
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States.
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19
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Chou Y, Nawabi H, Li J. Research hotspots and trends for axon regeneration (2000-2021): a bibliometric study and systematic review. Inflamm Regen 2022; 42:60. [PMID: 36476643 PMCID: PMC9727899 DOI: 10.1186/s41232-022-00244-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/23/2022] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Axons play an essential role in the connection of the nervous system with the rest of the body. Axon lesions often lead to permanent impairment of motor and cognitive functions and the interaction with the outside world. Studies focusing on axon regeneration have become a research field with considerable interest. The purpose of this study is to obtain an overall perspective of the research field of axonal regeneration and to assist the researchers and the funding agencies to better know the areas of greatest research opportunities. METHODS We conducted a bibliometric analysis and Latent Dirichlet Allocation (LDA) analysis of the global literature on axon regeneration based on the Web of Science (WoS) over the recent 22 years, to address the research hotspots, publication trends, and understudied areas. RESULTS A total of 21,018 articles were included, which in the recent two decades has increased by 125%. Among the top 12 hotspots, the annual productions rapidly increased in some topics, including axonal regeneration signaling pathway, axon guidance cues, neural circuits and functional recovery, nerve conduits, and cells transplant. Comparatively, the number of studies on axon regeneration inhibitors decreased. As for the topics focusing on nerve graft and transplantation, the annual number of papers tended to be relatively stable. Nevertheless, the underlying mechanisms of axon regrowth have not been completely uncovered. A lack of notable research on the epigenetic programs and noncoding RNAs regulation was observed. The significance of cell-type-specific data has been highlighted but with limited research working on that. Functional recovery from neuropathies also needs further studies. CONCLUSION The last two decades witnessed tremendous progress in the field of axon regeneration. There are still a lot of challenges to be tackled in translating these technologies into clinical practice.
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Affiliation(s)
- Yuyu Chou
- grid.413106.10000 0000 9889 6335Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100730 China ,grid.462307.40000 0004 0429 3736Grenoble Institut Neurosciences, Inserm, U1216, Grenoble Alpes University, Grenoble, France
| | - Homaira Nawabi
- grid.462307.40000 0004 0429 3736Grenoble Institut Neurosciences, Inserm, U1216, Grenoble Alpes University, Grenoble, France
| | - Jingze Li
- grid.216417.70000 0001 0379 7164Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha, 410083 People’s Republic of China ,grid.450307.50000 0001 0944 2786Laboratory 3SR, Grenoble Alpes University, CNRS UMR 5521, 38400 Grenoble, France
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20
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Zang Y, Chaudhari K, Bashaw GJ. Tace/ADAM17 is a bi-directional regulator of axon guidance that coordinates distinct Frazzled and Dcc receptor signaling outputs. Cell Rep 2022; 41:111785. [PMID: 36476876 DOI: 10.1016/j.celrep.2022.111785] [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: 05/23/2022] [Revised: 10/07/2022] [Accepted: 11/15/2022] [Indexed: 12/12/2022] Open
Abstract
Frazzled (Fra) and deleted in colorectal cancer (Dcc) are homologous receptors that promote axon attraction in response to netrin. In Drosophila, Fra also acts independently of netrin by releasing an intracellular domain (ICD) that activates gene transcription. How neurons coordinate these pathways to make accurate guidance decisions is unclear. Here we show that the ADAM metalloprotease Tace cleaves Fra, and this instructs the switch between the two pathways. Genetic manipulations that either increase or decrease Tace levels disrupt midline crossing of commissural axons. These conflicting phenotypes reflect Tace's function as a bi-directional regulator of axon guidance, a function conserved in its vertebrate homolog ADAM17: while Tace induces the formation of the Fra ICD to activate transcription, excessive Tace cleavage of Fra and Dcc suppresses the response to netrin. We propose that Tace and ADAM17 are key regulators of midline axon guidance by establishing the balance between netrin-dependent and netrin-independent signaling.
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Affiliation(s)
- Yixin Zang
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Karina Chaudhari
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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21
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Han P, She Y, Yang Z, Zhuang M, Wang Q, Luo X, Yin C, Zhu J, Jaffrey SR, Ji SJ. Cbln1 regulates axon growth and guidance in multiple neural regions. PLoS Biol 2022; 20:e3001853. [PMID: 36395107 PMCID: PMC9671368 DOI: 10.1371/journal.pbio.3001853] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 09/27/2022] [Indexed: 11/19/2022] Open
Abstract
The accurate construction of neural circuits requires the precise control of axon growth and guidance, which is regulated by multiple growth and guidance cues during early nervous system development. It is generally thought that the growth and guidance cues that control the major steps of axon development have been defined. Here, we describe cerebellin-1 (Cbln1) as a novel cue that controls diverse aspects of axon growth and guidance throughout the central nervous system (CNS) by experiments using mouse and chick embryos. Cbln1 has previously been shown to function in late neural development to influence synapse organization. Here, we find that Cbln1 has an essential role in early neural development. Cbln1 is expressed on the axons and growth cones of developing commissural neurons and functions in an autocrine manner to promote axon growth. Cbln1 is also expressed in intermediate target tissues and functions as an attractive guidance cue. We find that these functions of Cbln1 are mediated by neurexin-2 (Nrxn2), which functions as the Cbln1 receptor for axon growth and guidance. In addition to the developing spinal cord, we further show that Cbln1 functions in diverse parts of the CNS with major roles in cerebellar parallel fiber growth and retinal ganglion cell axon guidance. Despite the prevailing role of Cbln1 as a synaptic organizer, our study discovers a new and unexpected function for Cbln1 as a general axon growth and guidance cue throughout the nervous system.
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Affiliation(s)
- Peng Han
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yuanchu She
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Zhuoxuan Yang
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Mengru Zhuang
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Qingjun Wang
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiaopeng Luo
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Chaoqun Yin
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Junda Zhu
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Samie R. Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, New York, United States of America
- * E-mail: (SRJ); (SJJ)
| | - Sheng-Jian Ji
- School of Life Sciences, Department of Neuroscience and Department of Biology, Brain Research Center, Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
- * E-mail: (SRJ); (SJJ)
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22
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Yu H, Zhang J, Chen Y, Chen J, Qiu Y, Zhao Y, Li H, Xia S, Chen S, Zhu J. The adverse effects of fluxapyroxad on the neurodevelopment of zebrafish embryos. CHEMOSPHERE 2022; 307:135751. [PMID: 35863420 DOI: 10.1016/j.chemosphere.2022.135751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/13/2022] [Accepted: 07/14/2022] [Indexed: 06/15/2023]
Abstract
Fluxapyroxad (Flu), one of the succinate dehydrogenase-inhibited (SDHI) fungicides, has been extensively used in crop fungal disease control. Despite its increasing use in modern agriculture and long-term retention in the environment, the potentially toxic effects of Flu in vivo, especially on neurodevelopment, remain under-evaluated. In this study, zebrafish embryos were exposed to Flu at concentrations of 0.5, 0.75, and 1 mg/L for 96 h to evaluate the neurotoxicity of Flu. The results showed that Flu caused concentration-dependent malformations, including shorter body length, smaller head and eyes, and yolk sac edema. After exposure to Flu, larval zebrafish exhibited severe motor aberrations. Flu at a concentration of 1 mg/L significantly decreased dopamine level and notably altered acetylcholinesterase (AChE) activity and acetylcholine (ACh) content. Abnormal central nervous system (CNS) neurogenesis and disordered motor neuron development were observed in Tg (HUC-GFP) and Tg (hb9-GFP) zebrafish in Flu-treated groups. The expression of key genes involved in neurotransmission and neurodevelopment further proved that Flu impaired the zebrafish nervous system. This work contributes to our understanding of the neurotoxic effects and mechanisms induced by Flu in zebrafish and may help us take precautions against the neurotoxicity of Flu.
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Affiliation(s)
- Huilin Yu
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Junhui Zhang
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Yinghong Chen
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Juan Chen
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Yang Qiu
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Yan Zhao
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Honghao Li
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Shengyao Xia
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Shiguo Chen
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
| | - Jiajin Zhu
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
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23
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Gu J, Gao B, Zafar H, Chu B, Feng X, Ni Y, Xu L, Bao R. Thermo-sensitive hydrogel combined with SHH expressed RMSCs for rat spinal cord regeneration. Front Bioeng Biotechnol 2022; 10:1001396. [PMID: 36338109 PMCID: PMC9634076 DOI: 10.3389/fbioe.2022.1001396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 10/10/2022] [Indexed: 12/04/2022] Open
Abstract
Purpose: Spinal cord injury (SCI) has a damaging impact on patients, amid being a worldwide problem with no effective treatment. Herein, we reported a method for functional therapy of SCI in rats, wherein we combined thermo-sensitive hydrogel with Sonic Hedgehog (SHH) expressed in rat bone-marrow derived mesenchymal stem cells (RMSCs). Methods: Bone marrow-derived mesenchymal stem cells (BMSCs) were isolated from Sprague-Dawley (SD) female rats. The SHH was optimized and transferred into RMSCs via cationic liposomes, while thermo-sensitive hydrogel was reformed with hyaluronate (HA) and Pluronic F127. Then, a rat model with SCI was established accordingly by male SD rats and randomized into sham, model, RMSCs with hydrogel and SHH-RMSCs with hydrogel. The evaluation of SCI repair based on Basso, Beattie Bresnahanlocomotor rating scale (BBB scale) and inclined plate score. Immunofluorescence, immunohistochemistry and hematoxylin-eosin were utilized to explore the expression of protein (GFAP, GAP43, NF200 and MBP) and histopathology. Results: It was demonstrated that transfection of SHH with cationic liposomes exhibited more effect in RMSCs than lipofectamine 2000. As shown in SEM, 3.5% HA-F127 demonstrated porous structure. In the MTT and dead/live assay, 3.5% HA-F127 showed good biocompatibility for RMSCs. Both RMSCs and SHH-RMSCs groups could significantly promote BBB and inclined plate scores (p < 0.01) compared with the model. Furthermore, the SHH-RMSC group was significantly improved than RMSC with the expression of related proteins, where NF200, MBP, and GAP43 were principally enhanced with the GFAP expression being virtually down-regulated. Conclusion: All in all, the results suggested that transplantation of RMSCs with SHH could improve the function of SCI and promote nerve regeneration.
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Affiliation(s)
- Jun Gu
- School of Medicine, Yangzhou University, Yangzhou, China
- Department of Orthopedics, Xishan People’s Hospital, Wuxi, China
- *Correspondence: Jun Gu, ; Hajra Zafar,
| | - Biao Gao
- School of Medicine, Yangzhou University, Yangzhou, China
- Wuxi Xishan District Ehu Town Health Center, Wuxi, China
| | - Hajra Zafar
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
- *Correspondence: Jun Gu, ; Hajra Zafar,
| | - Bo Chu
- Department of Orthopedics, Xishan People’s Hospital, Wuxi, China
| | - Xiaojun Feng
- Department of Orthopedics, Xishan People’s Hospital, Wuxi, China
| | - Yinjie Ni
- Department of Orthopedics, Xishan People’s Hospital, Wuxi, China
| | - Lin Xu
- Department of Orthopedics, Xishan People’s Hospital, Wuxi, China
| | - Rui Bao
- Department of Pharmaceutics, School of Pharmacy, Jiangsu University, Zhenjiang, China
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A systemic cell stress signal confers neuronal resilience toward oxidative stress in a Hedgehog-dependent manner. Cell Rep 2022; 41:111488. [PMID: 36260999 PMCID: PMC9623505 DOI: 10.1016/j.celrep.2022.111488] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/04/2022] [Accepted: 09/21/2022] [Indexed: 11/22/2022] Open
Abstract
Cells possess several conserved adaptive mechanisms to respond to stress. Stress signaling is initiated to reestablish cellular homeostasis, but its effects on the tissue or systemic levels are far less understood. We report that the secreted luminal domain of the endoplasmic reticulum (ER) stress transducer CREB3L2 (which we name TAILS [transmissible activator of increased cell livability under stress]) is an endogenous, cell non-autonomous activator of neuronal resilience. In response to oxidative insults, neurons secrete TAILS, which potentiates hedgehog signaling through direct interaction with Sonic hedgehog (SHH) and its receptor PTCH1, leading to improved antioxidant signaling and mitochondrial function in neighboring neurons. In an in vivo model of ischemic brain injury, administration of TAILS enables survival of CNS neurons and fully preserves cognitive function in behavioral tests. Our findings reveal an SHH-mediated, cell non-autonomous branch of cellular stress signaling that confers resilience to oxidative stress in the mature brain, providing protection from ischemic neurodegeneration. Whether and how neurons can communicate stress to other neurons is poorly understood. Chung et al. demonstrate that oxidative stress in neurons leads to secretion of cell non-autonomous stress signaling protein. This protein, TAILS, induces neuronal resilience against cell stress in recipient cells in an SHH-dependent manner.
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Vaccaro G, Dumoulin A, Zuñiga NR, Bandtlow CE, Stoeckli ET. The Nogo-66 Receptors NgR1 and NgR3 Are Required for Commissural Axon Pathfinding. J Neurosci 2022; 42:4087-4100. [PMID: 35437280 PMCID: PMC9121835 DOI: 10.1523/jneurosci.1390-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022] Open
Abstract
Nogo-66 receptors (NgR1-3) are glycosylphosphatidyl inositol-linked proteins that belong to the leucine-rich repeat superfamily. Through binding to myelin-associated inhibitors, NgRs contribute to the inhibition of axonal regeneration after spinal cord injury. Their role in limiting synaptic plasticity and axonal outgrowth in the adult CNS has been described previously, but not much is known about their role during the development of the nervous system. Here, we show that NgR1 and NgR3 mRNAs are expressed during spinal cord development of the chicken embryo. In particular, they are expressed in the dI1 subpopulation of commissural neurons during the time when their axons navigate toward and across the floorplate, the ventral midline of the spinal cord. To assess a potential role of NgR1 and NgR3 in axon guidance, we downregulated them using in ovo RNAi and analyzed the trajectory of commissural axons by tracing them in open-book preparations of spinal cords. Our results show that loss of either NgR1 or NgR3 causes axons to stall in the midline area and to interfere with the rostral turn of postcrossing axons. In addition, we also show that NgR1, but not NgR3, requires neuronal PlexinA2 for the regulation of commissural axon guidance.SIGNIFICANCE STATEMENT Over the last decades, many studies have focused on the role of NgRs, particularly NgR1, in axonal regeneration in the injured adult CNS. Here, we show a physiological role of NgRs in guiding commissural axons during early development of the chicken spinal cord in vivo Both NgR1 and NgR3 are required for midline crossing and subsequent turning of postcrossing axons into the longitudinal axis of the spinal cord. NgR1, but not NgR3, forms a receptor complex with PlexinA2 during axon guidance. Overall, these findings provide a link between neural regenerative mechanisms and developmental processes.
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Affiliation(s)
- Giuseppe Vaccaro
- Institute of Neurobiochemistry, Biocenter, Medical University of Innsbruck, Innsbruck, 6020, Austria
- Department of Molecular Life Sciences, Neuroscience Center Zurich, Zurich, 8057, Switzerland
| | - Alexandre Dumoulin
- Department of Molecular Life Sciences, Neuroscience Center Zurich, Zurich, 8057, Switzerland
| | - Nikole R Zuñiga
- Department of Molecular Life Sciences, Neuroscience Center Zurich, Zurich, 8057, Switzerland
| | - Christine E Bandtlow
- Institute of Neurobiochemistry, Biocenter, Medical University of Innsbruck, Innsbruck, 6020, Austria
| | - Esther T Stoeckli
- Department of Molecular Life Sciences, Neuroscience Center Zurich, Zurich, 8057, Switzerland
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26
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Higgs VE, Das RM. Establishing neuronal polarity: microtubule regulation during neurite initiation. OXFORD OPEN NEUROSCIENCE 2022; 1:kvac007. [PMID: 38596701 PMCID: PMC10913830 DOI: 10.1093/oons/kvac007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/25/2022] [Accepted: 05/02/2022] [Indexed: 04/11/2024]
Abstract
The initiation of nascent projections, or neurites, from the neuronal cell body is the first stage in the formation of axons and dendrites, and thus a critical step in the establishment of neuronal architecture and nervous system development. Neurite formation relies on the polarized remodelling of microtubules, which dynamically direct and reinforce cell shape, and provide tracks for cargo transport and force generation. Within neurons, microtubule behaviour and structure are tightly controlled by an array of regulatory factors. Although microtubule regulation in the later stages of axon development is relatively well understood, how microtubules are regulated during neurite initiation is rarely examined. Here, we discuss how factors that direct microtubule growth, remodelling, stability and positioning influence neurite formation. In addition, we consider microtubule organization by the centrosome and modulation by the actin and intermediate filament networks to provide an up-to-date picture of this vital stage in neuronal development.
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Affiliation(s)
- Victoria E Higgs
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Raman M Das
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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27
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Wang W, Shiraishi R, Kawauchi D. Sonic Hedgehog Signaling in Cerebellar Development and Cancer. Front Cell Dev Biol 2022; 10:864035. [PMID: 35573667 PMCID: PMC9100414 DOI: 10.3389/fcell.2022.864035] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/28/2022] [Indexed: 12/30/2022] Open
Abstract
The sonic hedgehog (SHH) pathway regulates the development of the central nervous system in vertebrates. Aberrant regulation of SHH signaling pathways often causes neurodevelopmental diseases and brain tumors. In the cerebellum, SHH secreted by Purkinje cells is a potent mitogen for granule cell progenitors, which are the most abundant cell type in the mature brain. While a reduction in SHH signaling induces cerebellar structural abnormalities, such as hypoplasia in various genetic disorders, the constitutive activation of SHH signaling often induces medulloblastoma (MB), one of the most common pediatric malignant brain tumors. Based on the existing literature on canonical and non-canonical SHH signaling pathways, emerging basic and clinical studies are exploring novel therapeutic approaches for MB by targeting SHH signaling at distinct molecular levels. In this review, we discuss the present consensus on SHH signaling mechanisms, their roles in cerebellar development and tumorigenesis, and the recent advances in clinical trials for MB.
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Affiliation(s)
- Wanchen Wang
- Department of Biochemistry and Cellular Biology, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
| | - Ryo Shiraishi
- Department of Biochemistry and Cellular Biology, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
- Department of NCNP Brain Physiology and Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Daisuke Kawauchi
- Department of Biochemistry and Cellular Biology, National Center of Neurology and Psychiatry (NCNP), Tokyo, Japan
- *Correspondence: Daisuke Kawauchi,
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28
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Daly CA, Hall ET, Ogden SK. Regulatory mechanisms of cytoneme-based morphogen transport. Cell Mol Life Sci 2022; 79:119. [PMID: 35119540 PMCID: PMC8816744 DOI: 10.1007/s00018-022-04148-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/05/2022] [Accepted: 01/12/2022] [Indexed: 01/07/2023]
Abstract
During development and tissue homeostasis, cells must communicate with their neighbors to ensure coordinated responses to instructional cues. Cues such as morphogens and growth factors signal at both short and long ranges in temporal- and tissue-specific manners to guide cell fate determination, provide positional information, and to activate growth and survival responses. The precise mechanisms by which such signals traverse the extracellular environment to ensure reliable delivery to their intended cellular targets are not yet clear. One model for how this occurs suggests that specialized filopodia called cytonemes extend between signal-producing and -receiving cells to function as membrane-bound highways along which information flows. A growing body of evidence supports a crucial role for cytonemes in cell-to-cell communication. Despite this, the molecular mechanisms by which cytonemes are initiated, how they grow, and how they deliver specific signals are only starting to be revealed. Herein, we discuss recent advances toward improved understanding of cytoneme biology. We discuss similarities and differences between cytonemes and other types of cellular extensions, summarize what is known about how they originate, and discuss molecular mechanisms by which their activity may be controlled in development and tissue homeostasis. We conclude by highlighting important open questions regarding cytoneme biology, and comment on how a clear understanding of their function may provide opportunities for treating or preventing disease.
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Affiliation(s)
- Christina A Daly
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Pl. MS340, Memphis, TN, 38105, USA
- St. Jude Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Pl, MS 1500, Memphis, TN, 38105, USA
| | - Eric T Hall
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Pl. MS340, Memphis, TN, 38105, USA
| | - Stacey K Ogden
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Pl. MS340, Memphis, TN, 38105, USA.
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Ahmed G, Shinmyo Y. Multiple Functions of Draxin/Netrin-1 Signaling in the Development of Neural Circuits in the Spinal Cord and the Brain. Front Neuroanat 2021; 15:766911. [PMID: 34899198 PMCID: PMC8655782 DOI: 10.3389/fnana.2021.766911] [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] [Received: 08/30/2021] [Accepted: 10/22/2021] [Indexed: 11/30/2022] Open
Abstract
Axon guidance proteins play key roles in the formation of neural circuits during development. We previously identified an axon guidance cue, named draxin, that has no homology with other axon guidance proteins. Draxin is essential for the development of various neural circuits including the spinal cord commissure, corpus callosum, and thalamocortical projections. Draxin has been shown to not only control axon guidance through netrin-1 receptors, deleted in colorectal cancer (Dcc), and neogenin (Neo1) but also modulate netrin-1-mediated axon guidance and fasciculation. In this review, we summarize the multifaceted functions of draxin and netrin-1 signaling in neural circuit formation in the central nervous system. Furthermore, because recent studies suggest that the distributions and functions of axon guidance cues are highly regulated by glycoproteins such as Dystroglycan and Heparan sulfate proteoglycans, we discuss a possible function of glycoproteins in draxin/netrin-1-mediated axon guidance.
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Affiliation(s)
- Giasuddin Ahmed
- Department of Neuroscience and Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Yohei Shinmyo
- Department of Medical Neuroscience, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
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30
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Nectins and Nectin-like molecules in synapse formation and involvement in neurological diseases. Mol Cell Neurosci 2021; 115:103653. [PMID: 34242750 DOI: 10.1016/j.mcn.2021.103653] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 05/11/2021] [Accepted: 06/25/2021] [Indexed: 12/12/2022] Open
Abstract
Synapses are interneuronal junctions which form neuronal networks and play roles in a variety of functions, including learning and memory. Two types of junctions, synaptic junctions (SJs) and puncta adherentia junctions (PAJs), have been identified. SJs are found at all excitatory and inhibitory synapses whereas PAJs are found at excitatory synapses, but not inhibitory synapses, and particularly well developed at hippocampal mossy fiber giant excitatory synapses. Both SJs and PAJs are mediated by cell adhesion molecules (CAMs). Major CAMs at SJs are neuroligins-neurexins and Nectin-like molecules (Necls)/CADMs/SynCAMs whereas those at PAJs are nectins and cadherins. In addition to synaptic PAJs, extrasynaptic PAJs have been identified at contact sites between neighboring dendrites near synapses and regulate synapse formation. In addition to SJs and PAJs, a new type of cell adhesion apparatus different from these junctional apparatuses has been identified and named nectin/Necl spots. One nectin spot at contact sites between neighboring dendrites at extrasynaptic regions near synapses regulates synapse formation. Several members of nectins and Necls had been identified as viral receptors before finding their physiological functions as CAMs and evidence is accumulating that many nectins and Necls are related to onset and progression of neurological diseases. We review here nectin and Necls in synapse formation and involvement in neurological diseases.
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31
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Suciu SK, Long AB, Caspary T. Smoothened and ARL13B are critical in mouse for superior cerebellar peduncle targeting. Genetics 2021; 218:6300527. [PMID: 34132778 PMCID: PMC8864748 DOI: 10.1093/genetics/iyab084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/15/2021] [Indexed: 01/07/2023] Open
Abstract
Patients with the ciliopathy Joubert syndrome present with physical anomalies, intellectual disability, and a hindbrain malformation described as the "molar tooth sign" due to its appearance on an MRI. This radiological abnormality results from a combination of hypoplasia of the cerebellar vermis and inappropriate targeting of the white matter tracts of the superior cerebellar peduncles. ARL13B is a cilia-enriched regulatory GTPase established to regulate cell fate, cell proliferation, and axon guidance through vertebrate Hedgehog signaling. In patients, mutations in ARL13B cause Joubert syndrome. To understand the etiology of the molar tooth sign, we used mouse models to investigate the role of ARL13B during cerebellar development. We found that ARL13B regulates superior cerebellar peduncle targeting and these fiber tracts require Hedgehog signaling for proper guidance. However, in mouse, the Joubert-causing R79Q mutation in ARL13B does not disrupt Hedgehog signaling nor does it impact tract targeting. We found a small cerebellar vermis in mice lacking ARL13B function but no cerebellar vermis hypoplasia in mice expressing the Joubert-causing R79Q mutation. In addition, mice expressing a cilia-excluded variant of ARL13B that transduces Hedgehog normally showed normal tract targeting and vermis width. Taken together, our data indicate that ARL13B is critical for the control of cerebellar vermis width as well as superior cerebellar peduncle axon guidance, likely via Hedgehog signaling. Thus, our work highlights the complexity of ARL13B in molar tooth sign etiology.
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Affiliation(s)
- Sarah K Suciu
- Genetics and Molecular Biology Graduate Program, Emory University, Atlanta, GA 30322, USA,Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Alyssa B Long
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Tamara Caspary
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA,Corresponding author: Department of Human Genetics, 615 Michael Street, Suite 301, Atlanta, GA 30322.
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32
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New Tricks for an Old (Hedge)Hog: Sonic Hedgehog Regulation of Astrocyte Function. Cells 2021; 10:cells10061353. [PMID: 34070740 PMCID: PMC8228508 DOI: 10.3390/cells10061353] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 01/12/2023] Open
Abstract
The Sonic hedgehog (Shh) molecular signaling pathway is well established as a key regulator of neurodevelopment. It regulates diverse cellular behaviors, and its functions vary with respect to cell type, region, and developmental stage, reflecting the incredible pleiotropy of this molecular signaling pathway. Although it is best understood for its roles in development, Shh signaling persists into adulthood and is emerging as an important regulator of astrocyte function. Astrocytes play central roles in a broad array of nervous system functions, including synapse formation and function as well as coordination and orchestration of CNS inflammatory responses in pathological states. Neurons are the source of Shh in the adult, suggesting that Shh signaling mediates neuron-astrocyte communication, a novel role for this multifaceted pathway. Multiple roles for Shh signaling in astrocytes are increasingly being identified, including regulation of astrocyte identity, modulation of synaptic organization, and limitation of inflammation. This review discusses these novel roles for Shh signaling in regulating diverse astrocyte functions in the healthy brain and in pathology.
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33
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Ho EK, Stearns T. Hedgehog signaling and the primary cilium: implications for spatial and temporal constraints on signaling. Development 2021; 148:dev195552. [PMID: 33914866 PMCID: PMC8126410 DOI: 10.1242/dev.195552] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mechanisms of vertebrate Hedgehog signaling are linked to the biology of the primary cilium, an antenna-like organelle that projects from the surface of most vertebrate cell types. Although the advantages of restricting signal transduction to cilia are often noted, the constraints imposed are less frequently considered, and yet they are central to how Hedgehog signaling operates in developing tissues. In this Review, we synthesize current understanding of Hedgehog signal transduction, ligand secretion and transport, and cilia dynamics to explore the temporal and spatial constraints imposed by the primary cilium on Hedgehog signaling in vivo.
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Affiliation(s)
- Emily K. Ho
- Department of Developmental Biology, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Tim Stearns
- Department of Biology, Stanford University, Stanford, CA 94305, USA
- Department of Genetics, Stanford School of Medicine, Stanford, CA 94305, USA
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34
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Knickmeyer MD, Mateo JL, Heermann S. BMP Signaling Interferes with Optic Chiasm Formation and Retinal Ganglion Cell Pathfinding in Zebrafish. Int J Mol Sci 2021; 22:ijms22094560. [PMID: 33925390 PMCID: PMC8123821 DOI: 10.3390/ijms22094560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/19/2021] [Accepted: 04/24/2021] [Indexed: 11/17/2022] Open
Abstract
Decussation of axonal tracts is an important hallmark of vertebrate neuroanatomy resulting in one brain hemisphere controlling the contralateral side of the body and also computing the sensory information originating from that respective side. Here, we show that BMP interferes with optic chiasm formation and RGC pathfinding in zebrafish. Experimental induction of BMP4 at 15 hpf results in a complete ipsilateral projection of RGC axons and failure of commissural connections of the forebrain, in part as the result of an interaction with shh signaling, transcriptional regulation of midline guidance cues and an affected optic stalk morphogenesis. Experimental induction of BMP4 at 24 hpf, resulting in only a mild repression of forebrain shh ligand expression but in a broad expression of pax2a in the diencephalon, does not per se prevent RGC axons from crossing the midline. It nevertheless shows severe pathologies of RGC projections e.g., the fasciculation of RGC axons with the ipsilateral optic tract resulting in the innervation of one tectum by two eyes or the projection of RGC axons in the direction of the contralateral eye.
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Affiliation(s)
- Max D. Knickmeyer
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Faculty of Medicine, University Freiburg, 79104 Freiburg, Germany;
- Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany
| | - Juan L. Mateo
- Departamento de Informática, Universidad de Oviedo, Jesús Arias de Velasco, 33005 Oviedo, Spain;
| | - Stephan Heermann
- Department of Molecular Embryology, Institute of Anatomy and Cell Biology, Faculty of Medicine, University Freiburg, 79104 Freiburg, Germany;
- Correspondence:
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Hill SA, Fu M, Garcia ADR. Sonic hedgehog signaling in astrocytes. Cell Mol Life Sci 2021; 78:1393-1403. [PMID: 33079226 PMCID: PMC7904711 DOI: 10.1007/s00018-020-03668-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 09/02/2020] [Accepted: 10/05/2020] [Indexed: 01/12/2023]
Abstract
Astrocytes are complex cells that perform a broad array of essential functions in the healthy and injured nervous system. The recognition that these cells are integral components of various processes, including synapse formation, modulation of synaptic activity, and response to injury, underscores the need to identify the molecular signaling programs orchestrating these diverse functional properties. Emerging studies have identified the Sonic hedgehog (Shh) signaling pathway as an essential regulator of the molecular identity and functional properties of astrocytes. Well established as a powerful regulator of diverse neurodevelopmental processes in the embryonic nervous system, its functional significance in astrocytes is only beginning to be revealed. Notably, Shh signaling is active only in discrete subpopulations of astrocytes distributed throughout the brain, a feature that has potential to yield novel insights into functional specialization of astrocytes. Here, we discuss Shh signaling and emerging data that point to essential roles for this pleiotropic signaling pathway in regulating various functional properties of astrocytes in the healthy and injured brain.
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Affiliation(s)
- Steven A Hill
- Department of Biology, Drexel University, Philadelphia, PA, 19104, USA
| | - Marissa Fu
- Department of Biology, Drexel University, Philadelphia, PA, 19104, USA
| | - A Denise R Garcia
- Department of Biology, Drexel University, Philadelphia, PA, 19104, USA.
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA.
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Zhang C, Cui L, He W, Zhang X, Liu H. Dl-3-n-butylphthalide promotes neurite outgrowth of primary cortical neurons by Sonic Hedgehog signaling via upregulating Gap43. Exp Cell Res 2020; 398:112420. [PMID: 33296663 DOI: 10.1016/j.yexcr.2020.112420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 11/17/2020] [Accepted: 11/26/2020] [Indexed: 10/22/2022]
Abstract
Neurite outgrowth is the basis for wiring during the development of the nervous system. Dl-3-n-butylphthalide (NBP) has been recognized as a promising treatment to improve behavioral, neurological and cognitive outcomes in ischemic stroke. However, little is known about the effect and mechanism of NBP on the neurite outgrowth. In this study, we used different methods to investigate the potential effects of NBP on the neurite extension and plasticity of immature and mature primary cortical neurons and explored the underlying mechanisms. Our results demonstrated that in immature and mature cortical neurons, NBP promoted the neurite length and intersections, increased neuritic arborization, elevated numbers of neurite branch and terminal points and improved neurite complexity and plasticity of neuronal development processes. Besides, our data revealed that NBP promoted neurite extension and branching partly by activating Shh signaling pathway via increasing Gap43 expression both in immature and mature primary cortical neurons. The present study provided new insights into the contribution of NBP in neuronal plasticity and unveiled a novel pathway to induce Gap43 expression in primary cortical neurons.
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Affiliation(s)
- Cong Zhang
- Department of Radiology, Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China; Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, Shijiazhuang, Hebei, China
| | - Lili Cui
- Department of Neurology, Second Hospital of Hebei Medical University; Shijiazhuang, Hebei, China; Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, Shijiazhuang, Hebei, China
| | - Weiliang He
- Department of Neurology, Hebei General Hospital, Shijiazhuang, Hebei, China
| | - Xiangjian Zhang
- Department of Neurology, Second Hospital of Hebei Medical University; Shijiazhuang, Hebei, China; Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, Shijiazhuang, Hebei, China
| | - Huaijun Liu
- Department of Radiology, Second Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
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Alvarez S, Varadarajan SG, Butler SJ. Dorsal commissural axon guidance in the developing spinal cord. Curr Top Dev Biol 2020; 142:197-231. [PMID: 33706918 DOI: 10.1016/bs.ctdb.2020.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Commissural axons have been a key model system for identifying axon guidance signals in vertebrates. This review summarizes the current thinking about the molecular and cellular mechanisms that establish a specific commissural neural circuit: the dI1 neurons in the developing spinal cord. We assess the contribution of long- and short-range signaling while sequentially following the developmental timeline from the birth of dI1 neurons, to the extension of commissural axons first circumferentially and then contralaterally into the ventral funiculus.
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Affiliation(s)
- Sandy Alvarez
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Molecular Biology Interdepartmental Doctoral Program, University of California, Los Angeles, CA, United States
| | | | - Samantha J Butler
- Department of Neurobiology, University of California, Los Angeles, CA, United States; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, CA, United States.
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38
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Hedgehog signaling promotes endoneurial fibroblast migration and Vegf-A expression following facial nerve injury. Brain Res 2020; 1751:147204. [PMID: 33189691 DOI: 10.1016/j.brainres.2020.147204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 11/03/2020] [Accepted: 11/07/2020] [Indexed: 02/05/2023]
Abstract
BACKGROUND Peripheral nerve injuries are a common clinical problem which may result in permanent loss of motor or sensory function. A better understanding of the signaling pathways that lead to successful nerve regeneration may help in discovering new therapeutic targets. The Hedgehog (Hh) signaling pathway plays significant roles in nerve development and regeneration. In a mouse model of facial nerve injury, Hedgehog-responsive fibroblasts increase in number both at the site of injury and within the distal nerve. However, the role of these cells in facial nerve regeneration is not fully understood. We hypothesize that the Hh pathway plays an angiogenic and pro-migratory role following facial nerve injury. METHODS Hedgehog pathway modulators were applied to murine endoneurial fibroblasts isolated from the murine facial nerve. The impact of pathway modulation on endoneurial fibroblast migration and cell proliferation was assessed. Gene expression changes of known Hedgehog target genes and the key angiogenic factor Vegf-A were determined by qPCR. In vivo, mice were treated with pathway agonist (SAG21k) and injured facial nerve specimens were analyzed via immunofluorescence and in situ hybridization. RESULTS Hedgehog pathway activation in facial nerve fibroblasts via SAG21k treatment increases Gli1 and Ptch1 expression, the rate of cellular migration, and Vegf-A expression in vitro. In vivo, expression of Gli1 and Vegf-A expression appears to increase after injury, particularly at the site of nerve injury and the distal nerve, as detected by immunofluorescence and in situ hybridization. Additionally, Gli1 transcripts co-localize with Vegf-A following transection injury to the facial nerve. DISCUSSION These findings describe an angiogenic and pro-migratory role for the Hedgehog pathway mediated through effects on nerve fibroblasts. Given the critical role of Vegf-A in nerve regeneration, modulation of this pathway may represent a potential therapeutic target to improve facial nerve regeneration following injury.
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39
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Guo SY, Zhang Y, Zhu XY, Zhou JL, Li J, Li CQ, Wu LR. Developmental neurotoxicity and toxic mechanisms induced by olaquindox in zebrafish. J Appl Toxicol 2020; 41:549-560. [PMID: 33111391 DOI: 10.1002/jat.4062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/13/2020] [Accepted: 08/17/2020] [Indexed: 12/30/2022]
Abstract
Olaquindox (OLA) has been widely used as an animal feed additive in China for decades; however, its toxicity and toxic mechanisms have not been well investigated. In this study, the developmental neurotoxicity and toxic mechanisms of OLA were evaluated in zebrafish. Zebrafish embryos were exposed to different concentrations of OLA (25-1,000 mg/L) from 6 to 120 hours post fertilization (hpf). OLA exposure resulted in many abnormal phenotypes in zebrafish, including shortened body length, notochord degeneration, spinal curvature, brain apoptosis, damage of axon and peripheral motor neuron, and hepatotoxicity. Interestingly, OLA increased zebrafish spontaneous tail coiling, while reduced locomotor capacity. Quantitative polymerase chain reaction (Q-PCR) showed that the expression levels of nine marker genes for nervous system functions or development, namely, α1-tubulin, glial fibrillary acidic protein (gfap), myelin basic protein (mbp), synapsinII a (syn2a), sonic hedgehog a (shha), encoding HuC (elavl3), mesencephalic astrocyte-derived neurotrophic factor (manf) growth associated protein 43 (gap43), and acetylcholinesterase (ache) were all down-regulated significantly in zebrafish after treated with OLA. Besides, the anti-apoptotic and pro-apoptotic genes bcl-2/bax ratio was reduced. These results show that OLA exposure could cause severe developmental neurotoxicity in the early stages of zebrafish life and OLA might induce neurotoxicity by inhibiting the expression of neuro-developmental genes and promoting apoptosis.
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Affiliation(s)
- Sheng-Ya Guo
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Binwen Road, Hangzhou, 310053, China.,Research and Development Department, Hunter Biotechnology, Inc., Jiangling Road, Hangzhou, 310051, China
| | - Yong Zhang
- Research and Development Department, Hunter Biotechnology, Inc., Jiangling Road, Hangzhou, 310051, China
| | - Xiao-Yu Zhu
- Research and Development Department, Hunter Biotechnology, Inc., Jiangling Road, Hangzhou, 310051, China
| | - Jia-Li Zhou
- Research and Development Department, Hunter Biotechnology, Inc., Jiangling Road, Hangzhou, 310051, China
| | - Jiao Li
- Research and Development Department, Hunter Biotechnology, Inc., Jiangling Road, Hangzhou, 310051, China
| | - Chun-Qi Li
- Research and Development Department, Hunter Biotechnology, Inc., Jiangling Road, Hangzhou, 310051, China.,Research and Development Department, New Hunter Testing and Technology Co., Ltd, Xinjinhu Road, Nanjing, 210046, China
| | - Li-Ren Wu
- Laboratory Animal Regulatory Center, Hangzhou Medical College, Tianmushan Road, Hangzhou, 310013, China
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40
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Pasterkamp RJ, Burk K. Axon guidance receptors: Endocytosis, trafficking and downstream signaling from endosomes. Prog Neurobiol 2020; 198:101916. [PMID: 32991957 DOI: 10.1016/j.pneurobio.2020.101916] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/06/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
During the development of the nervous system, axons extend through complex environments. Growth cones at the axon tip allow axons to find and innervate their appropriate targets and form functional synapses. Axon pathfinding requires axons to respond to guidance signals and these cues need to be detected by specialized receptors followed by intracellular signal integration and translation. Several downstream signaling pathways have been identified for axon guidance receptors and it has become evident that these pathways are often initiated from intracellular vesicles called endosomes. Endosomes allow receptors to traffic intracellularly, re-locating receptors from one cellular region to another. The localization of axon guidance receptors to endosomal compartments is crucial for their function, signaling output and expression levels. For example, active receptors within endosomes can recruit downstream proteins to the endosomal membrane and facilitate signaling. Also, endosomal trafficking can re-locate receptors back to the plasma membrane to allow re-activation or mediate downregulation of receptor signaling via degradation. Accumulating evidence suggests that axon guidance receptors do not follow a pre-set default trafficking route but may change their localization within endosomes. This re-routing appears to be spatially and temporally regulated, either by expression of adaptor proteins or co-receptors. These findings shed light on how signaling in axon guidance is regulated and diversified - a mechanism which explains how a limited set of guidance cues can help to establish billions of neuronal connections. In this review, we summarize and discuss our current knowledge of axon guidance receptor trafficking and provide directions for future research.
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Affiliation(s)
- R J Pasterkamp
- Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, 3584 CG Utrecht, the Netherlands.
| | - K Burk
- Department of Neurology, University Medical Center Göttingen, 37075 Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration, 37075 Göttingen, Germany.
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41
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McCurdy EP, Chung KM, Benitez-Agosto CR, Hengst U. Promotion of Axon Growth by the Secreted End of a Transcription Factor. Cell Rep 2020; 29:363-377.e5. [PMID: 31597097 DOI: 10.1016/j.celrep.2019.08.101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/02/2019] [Accepted: 08/29/2019] [Indexed: 12/27/2022] Open
Abstract
Axon growth is regulated externally by attractive and repulsive cues generated in the environment. In addition, intrinsic pathways govern axon development, although the extent to which axons themselves can influence their own growth is unknown. We find that dorsal root ganglion (DRG) axons secrete a factor supporting axon growth and identify it as the C terminus of the ER stress-induced transcription factor CREB3L2, which is generated by site 2 protease (S2P) cleavage in sensory neurons. S2P and CREB3L2 knockdown or inhibition of axonal S2P interfere with the growth of axons, and C-terminal CREB3L2 is sufficient to rescue these effects. C-terminal CREB3L2 forms a complex with Shh and stabilizes its association with the Patched-1 receptor on developing axons. Our results reveal a neuron-intrinsic pathway downstream of S2P that promotes axon growth.
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Affiliation(s)
- Ethan P McCurdy
- Integrated Program in Cellular, Molecular and Biomedical Studies, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Kyung Min Chung
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Carlos R Benitez-Agosto
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Ulrich Hengst
- The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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42
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Gorla M, Bashaw GJ. Molecular mechanisms regulating axon responsiveness at the midline. Dev Biol 2020; 466:12-21. [PMID: 32818516 DOI: 10.1016/j.ydbio.2020.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/12/2020] [Accepted: 08/12/2020] [Indexed: 02/06/2023]
Abstract
During embryonic development in bilaterally symmetric organisms, correct midline crossing is important for the proper formation of functional neural circuits. The aberrant development of neural circuits can result in multiple neurodevelopmental disorders, including horizontal gaze palsy, congenital mirror movement disorder, and autism spectrum disorder. Thus, understanding the molecular mechanisms that regulate proper axon guidance at the midline can provide insights into the pathology of neurological disorders. The signaling mechanisms that regulate midline crossing have been extensively studied in the Drosophila ventral nerve cord and the mouse embryonic spinal cord. In this review, we discuss these axon guidance mechanisms, highlighting the most recent advances in the understanding of how commissural axons switch their responsiveness from attractants to repellents during midline crossing.
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Affiliation(s)
- Madhavi Gorla
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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43
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Suciu SK, Caspary T. Cilia, neural development and disease. Semin Cell Dev Biol 2020; 110:34-42. [PMID: 32732132 DOI: 10.1016/j.semcdb.2020.07.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 12/16/2022]
Abstract
Neural development requires a series of cellular events starting with cell specification, proliferation, and migration. Subsequently, axons and dendrites project from the cell surface to form connections to other neurons, interneurons and glia. Anomalies in any one of these steps can lead to malformation or malfunction of the nervous system. Here we review the critical role the primary cilium plays in the fundamental steps of neurodevelopment. By highlighting human diseases caused by mutations in cilia-associated proteins, it is clear that cilia are essential to multiple neural processes. Furthermore, we explore whether additional aspects of cilia regulation, most notably post-translational modification of the tubulin scaffold in cilia, play underappreciated roles in neural development. Finally, we discuss whether cilia-associated proteins function outside the cilium in some aspects of neurodevelopment. These data underscore both the importance of cilia in the nervous system and some outstanding questions in the field.
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Affiliation(s)
- Sarah K Suciu
- Genetics and Molecular Biology Graduate Program, USA; Department of Human Genetics, Emory University, Atlanta, GA 30322, Georgia
| | - Tamara Caspary
- Department of Human Genetics, Emory University, Atlanta, GA 30322, Georgia.
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44
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Bautista J, Chandrasekhar A, Komirishetty PK, Duraikannu A, Zochodne DW. Regenerative plasticity of intact human skin axons. J Neurol Sci 2020; 417:117058. [PMID: 32755738 DOI: 10.1016/j.jns.2020.117058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/01/2020] [Accepted: 07/22/2020] [Indexed: 01/29/2023]
Abstract
The evaluation of human epidermal innervation and its impact by disease has largely focused on rigorous immunohistochemical counts of PGP 9.5 labelled axons. In this brief and preliminary report, we expand the repertoire of epidermal axon markers to include those with an influence on their regenerative plasticity. We studied human lower limb punch skin samples with tandem analyses of their mRNA content using qRT-PCR. Normal human subjects (n = 11) and two patients with newly diagnosed CIDP were sampled with the latter undergoing serial tandem biopsies before and after 3 months of immunotherapy. Controls expressed regeneration proteins within dermal and epidermal axons: GAP43 (growth associated protein 43), Shh (sonic hedgehog) and SCG (superior cervical ganglion-10; stathmin 2). Moreover, this expression accompanied intraepidermal nerve fiber density (IENF) within normal established values. CIDP patients had lower IENF but also expressed GAP43, Shh, and SCG. Tandem qRT-PCR identified confirmed the presence not only of these plasticity markers but of additional regeneration related mRNAs. CIDP patients had marked elevation of several mRNAs, with improvement following treatment. The findings support the concept of dynamic skin axon plasticity in humans is relevant toward consideration of newer therapeutic approaches.
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Affiliation(s)
- J Bautista
- Division of Neurology, Department of Medicine, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - A Chandrasekhar
- Division of Neurology, Department of Medicine, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - P K Komirishetty
- Division of Neurology, Department of Medicine, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - A Duraikannu
- Division of Neurology, Department of Medicine, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - D W Zochodne
- Division of Neurology, Department of Medicine, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada.
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45
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LRRK2 mediates axon development by regulating Frizzled3 phosphorylation and growth cone-growth cone communication. Proc Natl Acad Sci U S A 2020; 117:18037-18048. [PMID: 32641508 PMCID: PMC7395514 DOI: 10.1073/pnas.1921878117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Axon-axon interactions are essential for axon guidance during nervous system wiring. However, it is unknown whether and how the growth cones communicate with each other while sensing and responding to guidance cues. We found that the Parkinson's disease gene, leucine-rich repeat kinase 2 (LRRK2), has an unexpected role in growth cone-growth cone communication. The LRRK2 protein acts as a scaffold and induces Frizzled3 hyperphosphorylation indirectly by recruiting other kinases and also directly phosphorylates Frizzled3 on threonine 598 (T598). In LRRK1 or LRRK2 single knockout, LRRK1/2 double knockout, and LRRK2 G2019S knockin, the postcrossing spinal cord commissural axons are disorganized and showed anterior-posterior guidance errors after midline crossing. Growth cones from either LRRK2 knockout or G2019S knockin mice showed altered interactions, suggesting impaired communication. Intercellular interaction between Frizzled3 and Vangl2 is essential for planar cell polarity signaling. We show here that this interaction is regulated by phosphorylation of Frizzled3 at T598 and can be regulated by LRRK2 in a kinase activity-dependent way. In the LRRK1/2 double knockout or LRRK2 G2019S knockin, the dopaminergic axon bundle in the midbrain was significantly widened and appeared disorganized, showing aberrant posterior-directed growth. Our findings demonstrate that LRRK2 regulates growth cone-growth cone communication in axon guidance and that both loss-of-function mutation and a gain-of-function mutation (G2019S) cause axon guidance defects in development.
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46
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Ulisse V, Dey S, Rothbard DE, Zeevi E, Gokhman I, Dadosh T, Minis A, Yaron A. Regulation of axonal morphogenesis by the mitochondrial protein Efhd1. Life Sci Alliance 2020; 3:3/7/e202000753. [PMID: 32414840 PMCID: PMC7232985 DOI: 10.26508/lsa.202000753] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/12/2022] Open
Abstract
During development, neurons adjust their energy balance to meet the high demands of robust axonal growth and branching. The mechanisms that regulate this tuning are largely unknown. Here, we show that sensory neurons lacking liver kinase B1 (Lkb1), a master regulator of energy homeostasis, exhibit impaired axonal growth and branching. Biochemical analysis of these neurons revealed reduction in axonal ATP levels, whereas transcriptome analysis uncovered down-regulation of Efhd1 (EF-hand domain family member D1), a mitochondrial Ca2+-binding protein. Genetic ablation of Efhd1 in mice resulted in reduced axonal morphogenesis as well as enhanced neuronal death. Strikingly, this ablation causes mitochondrial dysfunction and a decrease in axonal ATP levels. Moreover, Efhd1 KO sensory neurons display shortened mitochondria at the axonal growth cones, activation of the AMP-activated protein kinase (AMPK)-Ulk (Unc-51-like autophagy-activating kinase 1) pathway and an increase in autophagic flux. Overall, this work uncovers a new mitochondrial regulator that is required for axonal morphogenesis.
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Affiliation(s)
- Valeria Ulisse
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Swagata Dey
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Deborah E Rothbard
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Einav Zeevi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Irena Gokhman
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Tali Dadosh
- Department of Chemical Research Support, Faculty of Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Adi Minis
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Avraham Yaron
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
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47
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Seo J, Youn W, Choi JY, Cho H, Choi H, Lanara C, Stratakis E, Choi IS. Neuro-taxis: Neuronal movement in gradients of chemical and physical environments. Dev Neurobiol 2020; 80:361-377. [PMID: 32304173 DOI: 10.1002/dneu.22749] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 04/13/2020] [Indexed: 12/15/2022]
Abstract
Environmental chemical and physical cues dynamically interact with migrating neurons and sprouting axons, and in particular, the gradients of environmental cues are regarded as one of the factors intimately involved in the neuronal movement. Since a growth cone was first described by Cajal, more than one century ago, chemical gradients have been suggested as one of the mechanisms by which the neurons determine proper paths and destinations. However, the gradients of physical cues, such as stiffness and topography, which also interact constantly with the neurons and their axons as a component of the extracellular environments, have rarely been noted regarding the guidance of neurons, despite their gradually increasingly reported influences in the case of nonneuronal-cell migration. In this review, we discuss chemical (i.e., chemo- and hapto-) and physical (i.e., duro-) taxis phenomena on the movement of neurons including axonal elongation. In addition, we suggest topotaxis, the most recently proposed physical-taxis phenomenon, as another potential mechanism in the neuronal movement, based on the reports of neuronal recognition of and responses to nanotopography.
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Affiliation(s)
| | - Wongu Youn
- Department of Chemistry, KAIST, Daejeon, Korea
| | - Ji Yu Choi
- Department of Chemistry, KAIST, Daejeon, Korea
| | | | | | - Christina Lanara
- Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece
| | - Emmanuel Stratakis
- Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion, Crete, Greece.,Physics Department, University of Crete, Heraklion, Crete, Greece
| | - Insung S Choi
- Department of Chemistry, KAIST, Daejeon, Korea.,Department of Bio and Brain Engineering, KAIST, Daejeon, Korea
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48
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Toro-Tapia G, Das RM. Primary cilium remodeling mediates a cell signaling switch in differentiating neurons. SCIENCE ADVANCES 2020; 6:eabb0601. [PMID: 32494754 PMCID: PMC7252506 DOI: 10.1126/sciadv.abb0601] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/09/2020] [Indexed: 05/28/2023]
Abstract
Cellular differentiation leads to the formation of specialized cell types and complex morphological variations. Often, differentiating cells transition between states by switching how they respond to the signaling environment. However, the mechanisms regulating these transitions are poorly understood. Differentiating neurons delaminate from the neuroepithelium through the regulated process of apical abscission, which mediates an acute loss of polarity and primary cilium disassembly. Using high-resolution live-cell imaging in chick neural tube, we show that these cells retain an Arl13b+ particle, which elongates and initiates intraflagellar trafficking as it transits toward the cell body, indicating primary cilium remodeling. Notably, disrupting cilia during and after remodeling inhibits axon extension and leads to axon collapse, respectively. Furthermore, cilium remodeling corresponds to a switch from a canonical to noncanonical cellular response to Shh. This work transforms our understanding of how cells can rapidly reinterpret signals to produce qualitatively different responses within the same tissue context.
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Affiliation(s)
- Gabriela Toro-Tapia
- Division of Molecular and Cellular Function, Faculty of Biology Medicine and Health, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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49
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Kim Y, Lee J, Seppala M, Cobourne MT, Kim SH. Ptch2/Gas1 and Ptch1/Boc differentially regulate Hedgehog signalling in murine primordial germ cell migration. Nat Commun 2020; 11:1994. [PMID: 32332736 PMCID: PMC7181751 DOI: 10.1038/s41467-020-15897-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 04/01/2020] [Indexed: 12/24/2022] Open
Abstract
Gas1 and Boc/Cdon act as co-receptors in the vertebrate Hedgehog signalling pathway, but the nature of their interaction with the primary Ptch1/2 receptors remains unclear. Here we demonstrate, using primordial germ cell migration in mouse as a developmental model, that specific hetero-complexes of Ptch2/Gas1 and Ptch1/Boc mediate the process of Smo de-repression with different kinetics, through distinct modes of Hedgehog ligand reception. Moreover, Ptch2-mediated Hedgehog signalling induces the phosphorylation of Creb and Src proteins in parallel to Gli induction, identifying a previously unknown Ptch2-specific signal pathway. We propose that although Ptch1 and Ptch2 functionally overlap in the sequestration of Smo, the spatiotemporal expression of Boc and Gas1 may determine the outcome of Hedgehog signalling through compartmentalisation and modulation of Smo-downstream signalling. Our study identifies the existence of a divergent Hedgehog signal pathway mediated by Ptch2 and provides a mechanism for differential interpretation of Hedgehog signalling in the germ cell niche. How co-receptors Gas1 and Boc interact with Ptch1/2 receptors and regulate Hh signalling is unclear. Here, the authors demonstrate that the spatiotemporal expression of Gas1 and Boc determines how Hh signalling affects the dynamic migration of murine primordial germ cells.
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Affiliation(s)
- Yeonjoo Kim
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, UK
| | - Jiyoung Lee
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, UK
| | - Maisa Seppala
- Centre for Craniofacial and Regenerative Biology, Faculty of Dental, Oral and Craniofacial Sciences King's College London Floor 27, Guy's Hospital, London, SE1 9RT, UK
| | - Martyn T Cobourne
- Centre for Craniofacial and Regenerative Biology, Faculty of Dental, Oral and Craniofacial Sciences King's College London Floor 27, Guy's Hospital, London, SE1 9RT, UK
| | - Soo-Hyun Kim
- Molecular and Clinical Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, UK.
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50
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Delmotte Q, Diabira D, Belaidouni Y, Hamze M, Kochmann M, Montheil A, Gaiarsa JL, Porcher C, Belgacem YH. Sonic Hedgehog Signaling Agonist (SAG) Triggers BDNF Secretion and Promotes the Maturation of GABAergic Networks in the Postnatal Rat Hippocampus. Front Cell Neurosci 2020; 14:98. [PMID: 32425757 PMCID: PMC7212340 DOI: 10.3389/fncel.2020.00098] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
Sonic hedgehog (Shh) signaling plays critical roles during early central nervous system development, such as neural cell proliferation, patterning of the neural tube and neuronal differentiation. While Shh signaling is still present in the postnatal brain, the roles it may play are, however, largely unknown. In particular, Shh signaling components are found at the synaptic junction in the maturing hippocampus during the first two postnatal weeks. This period is characterized by the presence of ongoing spontaneous synaptic activity at the cellular and network levels thought to play important roles in the onset of neuronal circuit formation and synaptic plasticity. Here, we demonstrate that non-canonical Shh signaling increases the frequency of the synchronized electrical activity called Giant Depolarizing Potentials (GDP) and enhances spontaneous GABA post-synaptic currents in the rodent hippocampus during the early postnatal period. This effect is mediated specifically through the Shh co-receptor Smoothened via intracellular Ca2+ signal and the activation of the BDNF-TrkB signaling pathway. Given the importance of these spontaneous events on neuronal network maturation and refinement, this study opens new perspectives for Shh signaling on the control of early stages of postnatal brain maturation and physiology.
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Affiliation(s)
- Quentin Delmotte
- Aix-Marseille Univ, Marseille, France.,INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Diabe Diabira
- INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Yasmine Belaidouni
- Aix-Marseille Univ, Marseille, France.,INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Mira Hamze
- Aix-Marseille Univ, Marseille, France.,INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Marine Kochmann
- Aix-Marseille Univ, Marseille, France.,Institut des Neurosciences de La Timone, Marseille, France
| | - Aurélie Montheil
- Aix-Marseille Univ, Marseille, France.,INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Jean-Luc Gaiarsa
- Aix-Marseille Univ, Marseille, France.,INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Christophe Porcher
- Aix-Marseille Univ, Marseille, France.,INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
| | - Yesser H Belgacem
- INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, Marseille, France.,INMED (Institut de Neurobiologie de la Méditerranée), Parc Scientifique de Luminy, Marseille, France
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