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Bear R, Sloan SA, Caspary T. Primary cilia shape postnatal astrocyte development through Sonic Hedgehog signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.17.618851. [PMID: 39464094 PMCID: PMC11507945 DOI: 10.1101/2024.10.17.618851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/29/2024]
Abstract
Primary cilia function as specialized signaling centers that regulate many cellular processes including neuron and glia development. Astrocytes possess cilia, but the function of cilia in astrocyte development remains largely unexplored. Critically, dysfunction of either astrocytes or cilia contributes to molecular changes observed in neurodevelopmental disorders. Here, we show that a sub-population of developing astrocytes in the prefrontal cortex are ciliated. This population corresponds to proliferating astrocytes and largely expresses the ciliary protein ARL13B. Genetic ablation of astrocyte cilia in vivo at two distinct stages of astrocyte development results in changes to Sonic Hedgehog (Shh) transcriptional targets. We show that Shh activity is decreased in immature and mature astrocytes upon loss of cilia. Furthermore, loss of cilia in immature astrocytes results in decreased astrocyte proliferation and loss of cilia in mature astrocytes causes enlarged astrocyte morphology. Together, these results indicate that astrocytes require cilia for Shh signaling throughout development and uncover functions for astrocyte cilia in regulating astrocyte proliferation and maturation. This expands our fundamental knowledge of astrocyte development and cilia function to advance our understanding of neurodevelopmental disorders.
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Affiliation(s)
- Rachel Bear
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street Suite 301, Atlanta GA 30322
- Graduate Program in Neuroscience
| | - Steven A. Sloan
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street Suite 301, Atlanta GA 30322
| | - Tamara Caspary
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street Suite 301, Atlanta GA 30322
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2
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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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3
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Liu X, Yam PT, Schlienger S, Cai E, Zhang J, Chen WJ, Torres Gutierrez O, Jimenez Amilburu V, Ramamurthy V, Ting AY, Branon TC, Cayouette M, Gen R, Marks T, Kong JH, Charron F, Ge X. Numb positively regulates Hedgehog signaling at the ciliary pocket. Nat Commun 2024; 15:3365. [PMID: 38664376 PMCID: PMC11045789 DOI: 10.1038/s41467-024-47244-1] [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: 07/16/2022] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Hedgehog (Hh) signaling relies on the primary cilium, a cell surface organelle that serves as a signaling hub for the cell. Using proximity labeling and quantitative proteomics, we identify Numb as a ciliary protein that positively regulates Hh signaling. Numb localizes to the ciliary pocket and acts as an endocytic adaptor to incorporate Ptch1 into clathrin-coated vesicles, thereby promoting Ptch1 exit from the cilium, a key step in Hh signaling activation. Numb loss impedes Sonic hedgehog (Shh)-induced Ptch1 exit from the cilium, resulting in reduced Hh signaling. Numb loss in spinal neural progenitors reduces Shh-induced differentiation into cell fates reliant on high Hh activity. Genetic ablation of Numb in the developing cerebellum impairs the proliferation of granule cell precursors, a Hh-dependent process, resulting in reduced cerebellar size. This study highlights Numb as a regulator of ciliary Ptch1 levels during Hh signal activation and demonstrates the key role of ciliary pocket-mediated endocytosis in cell signaling.
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Affiliation(s)
- Xiaoliang Liu
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95340, USA
| | - Patricia T Yam
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
| | - Sabrina Schlienger
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, H3A 0G4, Canada
| | - Eva Cai
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95340, USA
| | - Jingyi Zhang
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95340, USA
| | - Wei-Ju Chen
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Department of Biology, McGill University, Montreal, QC, H3A 0G4, Canada
| | - Oscar Torres Gutierrez
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95340, USA
| | | | - Vasanth Ramamurthy
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
| | - Alice Y Ting
- Departments of Genetics, of Biology, and by courtesy, of Chemistry, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Tess C Branon
- Departments of Genetics, of Biology, and by courtesy, of Chemistry, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Interline Therapeutics, South San Francisco, CA, USA
| | - Michel Cayouette
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, H3A 0G4, Canada
- Department of Medicine, University of Montreal, Montreal, QC, H3T 1J4, Canada
| | - Risako Gen
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Tessa Marks
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Jennifer H Kong
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Frédéric Charron
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada.
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, H3A 0G4, Canada.
- Department of Medicine, University of Montreal, Montreal, QC, H3T 1J4, Canada.
| | - Xuecai Ge
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95340, USA.
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4
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Bear RM, Caspary T. Uncovering cilia function in glial development. Ann Hum Genet 2024; 88:27-44. [PMID: 37427745 PMCID: PMC10776815 DOI: 10.1111/ahg.12519] [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: 03/31/2023] [Revised: 06/14/2023] [Accepted: 06/19/2023] [Indexed: 07/11/2023]
Abstract
Primary cilia play critical roles in regulating signaling pathways that underlie several developmental processes. In the nervous system, cilia are known to regulate signals that guide neuron development. Cilia dysregulation is implicated in neurological diseases, and the underlying mechanisms remain poorly understood. Cilia research has predominantly focused on neurons and has overlooked the diverse population of glial cells in the brain. Glial cells play essential roles during neurodevelopment, and their dysfunction contributes to neurological disease; however, the relationship between cilia function and glial development is understudied. Here we review the state of the field and highlight the glial cell types where cilia are found and the ciliary functions that are linked to glial development. This work uncovers the importance of cilia in glial development and raises outstanding questions for the field. We are poised to make progress in understanding the function of glial cilia in human development and their contribution to neurological diseases.
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Affiliation(s)
- Rachel M. Bear
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Suite 301, Atlanta GA 30322
- Graduate Program in Neuroscience
| | - Tamara Caspary
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Suite 301, Atlanta GA 30322
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5
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Xie Y, Reid CM, Granados AA, Garcia MT, Dale-Huang F, Hanson SM, Mancia W, Liu J, Adam M, Mosto O, Pisco AO, Alvarez-Buylla A, Harwell CC. Developmental origin and local signals cooperate to determine septal astrocyte identity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.08.561428. [PMID: 37873089 PMCID: PMC10592657 DOI: 10.1101/2023.10.08.561428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Astrocyte specification during development is influenced by both intrinsic and extrinsic factors, but the precise contribution of each remains poorly understood. Here we show that septal astrocytes from Nkx2.1 and Zic4 expressing progenitor zones are allocated into non-overlapping domains of the medial (MS) and lateral septal nuclei (LS) respectively. Astrocytes in these areas exhibit distinctive molecular and morphological features tailored to the unique cellular and synaptic circuit environment of each nucleus. Using single-nucleus (sn) RNA sequencing, we trace the developmental trajectories of cells in the septum and find that neurons and astrocytes undergo region and developmental stage-specific local cell-cell interactions. We show that expression of the classic morphogens Sonic hedgehog (Shh) and Fibroblast growth factors (Fgfs) by MS and LS neurons respectively, functions to promote the molecular specification of local astrocytes in each region. Finally, using heterotopic cell transplantation, we show that both morphological and molecular specifications of septal astrocytes are highly dependent on the local microenvironment, regardless of developmental origins. Our data highlights the complex interplay between intrinsic and extrinsic factors shaping astrocyte identities and illustrates the importance of the local environment in determining astrocyte functional specialization.
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Affiliation(s)
- Yajun Xie
- Department of Neurology, University of California, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA
| | - Christopher M. Reid
- Department of Neurology, University of California, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA
- Department of Neurobiology, Harvard Medical School, Boston, MA
- Ph.D. Program in Neuroscience, Harvard University, Boston, MA
| | | | - Miguel Turrero Garcia
- Department of Neurology, University of California, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA
| | - Fiona Dale-Huang
- Department of Neurology, University of California, San Francisco, CA
- Department of Neurological Surgery, University of California, San Francisco, CA
| | - Sarah M. Hanson
- Department of Neurology, University of California, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA
| | - Walter Mancia
- Department of Neurology, University of California, San Francisco, CA
- Department of Neurological Surgery, University of California, San Francisco, CA
| | - Jonathan Liu
- Chan Zuckerberg Biohub San Francisco, San Francisco, CA
| | - Manal Adam
- Department of Neurology, University of California, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA
| | - Olivia Mosto
- Department of Neurobiology, Harvard Medical School, Boston, MA
| | | | - Arturo Alvarez-Buylla
- Department of Neurology, University of California, San Francisco, CA
- Department of Neurological Surgery, University of California, San Francisco, CA
| | - Corey C. Harwell
- Department of Neurology, University of California, San Francisco, CA
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, San Francisco, CA
- Chan Zuckerberg Biohub San Francisco, San Francisco, CA
- Lead contact
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6
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Lencer E, Rains A, Binne E, Prekeris R, Artinger KB. Mutations in cdon and boc affect trunk neural crest cell migration and slow-twitch muscle development in zebrafish. Development 2023; 150:dev201304. [PMID: 37390228 PMCID: PMC10357035 DOI: 10.1242/dev.201304] [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: 10/04/2022] [Accepted: 06/22/2023] [Indexed: 07/02/2023]
Abstract
The transmembrane proteins cdon and boc are implicated in regulating hedgehog signaling during vertebrate development. Recent work showing roles for these genes in axon guidance and neural crest cell migration suggest that cdon and boc may play additional functions in regulating directed cell movements. We use newly generated and existing mutants to investigate a role for cdon and boc in zebrafish neural crest cell migration. We find that single mutant embryos exhibit normal neural crest phenotypes, but that neural crest migration is strikingly disrupted in double cdon;boc mutant embryos. We further show that this migration phenotype is associated with defects in the differentiation of slow-twitch muscle cells, and the loss of a Col1a1a-containing extracellular matrix, suggesting that neural crest defects may be a secondary consequence to defects in mesoderm development. Combined, our data add to a growing literature showing that cdon and boc act synergistically to promote hedgehog signaling during vertebrate development, and suggest that the zebrafish can be used to study the function of hedgehog receptor paralogs.
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Affiliation(s)
- Ezra Lencer
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Addison Rains
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
- Cell Biology, Stem Cells and Development Graduate Program, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Erin Binne
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
| | - Kristin B. Artinger
- Department of Craniofacial Biology, University of Colorado, Anschutz Medical Campus Aurora, CO 80045, USA
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, USA
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7
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Arcuschin CD, Pinkasz M, Schor IE. Mechanisms of robustness in gene regulatory networks involved in neural development. Front Mol Neurosci 2023; 16:1114015. [PMID: 36814969 PMCID: PMC9940843 DOI: 10.3389/fnmol.2023.1114015] [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: 12/02/2022] [Accepted: 01/16/2023] [Indexed: 02/08/2023] Open
Abstract
The functions of living organisms are affected by different kinds of perturbation, both internal and external, which in many cases have functional effects and phenotypic impact. The effects of these perturbations become particularly relevant for multicellular organisms with complex body patterns and cell type heterogeneity, where transcriptional programs controlled by gene regulatory networks determine, for example, the cell fate during embryonic development. Therefore, an essential aspect of development in these organisms is the ability to maintain the functionality of their genetic developmental programs even in the presence of genetic variation, changing environmental conditions and biochemical noise, a property commonly termed robustness. We discuss the implication of different molecular mechanisms of robustness involved in neurodevelopment, which is characterized by the interplay of many developmental programs at a molecular, cellular and systemic level. We specifically focus on processes affecting the function of gene regulatory networks, encompassing transcriptional regulatory elements and post-transcriptional processes such as miRNA-based regulation, but also higher order regulatory organization, such as gene network topology. We also present cases where impairment of robustness mechanisms can be associated with neurodevelopmental disorders, as well as reasons why understanding these mechanisms should represent an important part of the study of gene regulatory networks driving neural development.
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Affiliation(s)
- Camila D. Arcuschin
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Universidad de Buenos Aires—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marina Pinkasz
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Universidad de Buenos Aires—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Ignacio E. Schor
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Universidad de Buenos Aires—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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8
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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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9
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Lacomme M, Hales SC, Brown TW, Stevanovic K, Jolicoeur C, Cai J, Bois T, Desrosiers M, Dalkara D, Cayouette M. Numb regulates Tau levels and prevents neurodegeneration in tauopathy mouse models. SCIENCE ADVANCES 2022; 8:eabm4295. [PMID: 36260685 PMCID: PMC9581485 DOI: 10.1126/sciadv.abm4295] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 09/07/2022] [Indexed: 06/01/2023]
Abstract
Accumulation of the microtubule-associated protein Tau is linked to neuronal cell death in tauopathies, but how intraneuronal Tau levels are regulated in health and disease remains unclear. Here, we show that conditional inactivation of the trafficking adaptor protein Numb in retinal ganglion cells (RGCs) increases Tau levels and leads to axonal blebbing, which is followed by neuronal cell loss in aged mice. In the TauP301S mouse model of tauopathy, conditional inactivation of Numb in RGCs and spinal motoneurons accelerates neurodegeneration, and loss of Numb in motoneurons also leads to precocious hindlimb paralysis. Conversely, overexpression of the long isoform of Numb (Numb-72) decreases intracellular Tau levels and reduces axonal blebbing in TauP301S RGCs, leading to improved electrical activity in cultured neurons and improves performance in a visually guided behavior test in vivo. These results uncover Numb as a key regulator of intracellular Tau levels and identify Numb-72 as a potential therapeutic factor for tauopathies.
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Affiliation(s)
- Marine Lacomme
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Sarah C. Hales
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Thomas W. Brown
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Katarina Stevanovic
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Christine Jolicoeur
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Jenny Cai
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Therence Bois
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
| | - Melissa Desrosiers
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Deniz Dalkara
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Michel Cayouette
- Cellular Neurobiology Research Unit, Institut de recherches cliniques de Montréal (IRCM), Montreal, QC H2W 1R7, Canada
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
- Department of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
- Department of Anatomy and Cell Biology, Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
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10
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Wang S, Tanaka Y, Xu Y, Takeda S, Hirokawa N. KIF3B promotes a PI3K signaling gradient causing changes in a Shh protein gradient and suppressing polydactyly in mice. Dev Cell 2022; 57:2273-2289.e11. [DOI: 10.1016/j.devcel.2022.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 07/27/2022] [Accepted: 09/13/2022] [Indexed: 11/03/2022]
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11
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Reciprocal Regulation of Shh Trafficking and H2O2 Levels via a Noncanonical BOC-Rac1 Pathway. Antioxidants (Basel) 2022; 11:antiox11040718. [PMID: 35453403 PMCID: PMC9025708 DOI: 10.3390/antiox11040718] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/25/2022] [Accepted: 04/03/2022] [Indexed: 11/21/2022] Open
Abstract
Among molecules that bridge environment, cell metabolism, and cell signaling, hydrogen peroxide (H2O2) recently appeared as an emerging but central player. Its level depends on cell metabolism and environment and was recently shown to play key roles during embryogenesis, contrasting with its long-established role in disease progression. We decided to explore whether the secreted morphogen Sonic hedgehog (Shh), known to be essential in a variety of biological processes ranging from embryonic development to adult tissue homeostasis and cancers, was part of these interactions. Here, we report that H2O2 levels control key steps of Shh delivery in cell culture: increased levels reduce primary secretion, stimulate endocytosis and accelerate delivery to recipient cells; in addition, physiological in vivo modulation of H2O2 levels changes Shh distribution and tissue patterning. Moreover, a feedback loop exists in which Shh trafficking controls H2O2 synthesis via a non-canonical BOC-Rac1 pathway, leading to cytoneme growth. Our findings reveal that Shh directly impacts its own distribution, thus providing a molecular explanation for the robustness of morphogenesis to both environmental insults and individual variability.
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12
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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: 30] [Impact Index Per Article: 7.5] [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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13
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Liu K, Lv Z, Huang H, Yu S, Xiao L, Li X, Li G, Liu F. FGF3 from the Hypothalamus Regulates the Guidance of Thalamocortical Axons. Dev Neurosci 2021; 42:208-216. [PMID: 33684917 DOI: 10.1159/000513534] [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: 08/08/2020] [Accepted: 12/02/2020] [Indexed: 11/19/2022] Open
Abstract
Thalamus is an important sensory relay station: afferent sensory information, except olfactory signals, is transmitted by thalamocortical axons (TCAs) to the cerebral cortex. The pathway choice of TCAs depends on diverse diffusible or substrate-bound guidance cues in the environment. Not only classical guidance cues (ephrins, slits, semaphorins, and netrins), morphogens, which exerts patterning effects during early embryonic development, can also help axons navigate to their targets at later development stages. Here, expression analyses reveal that morphogen Fibroblast growth factor (FGF)-3 is expressed in the chick ventral diencephalon, hypothalamus, during the pathfinding of TCAs. Then, using in vitro analyses in chick explants, we identify a concentration-dependent effect of FGF3 on thalamic axons: attractant 100 ng/mL FGF3 transforms to a repellent at high concentration 500 ng/mL. Moreover, inhibition of FGF3 guidance functions indicates that FGF3 signaling is necessary for the correct navigation of thalamic axons. Together, these studies demonstrate a direct effect for the member of FGF7 subfamily, FGF3, in the axonal pathfinding of TCAs.
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Affiliation(s)
- Kuan Liu
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Zhongsheng Lv
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Hong Huang
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Shuyang Yu
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Li Xiao
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Xiang Li
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Gang Li
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China
| | - Fang Liu
- School of Basic Medical Sciences, Medical college of Nanchang University, Nanchang, China,
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14
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Dorskind JM, Kolodkin AL. Revisiting and refining roles of neural guidance cues in circuit assembly. Curr Opin Neurobiol 2021; 66:10-21. [PMID: 32823181 PMCID: PMC10725571 DOI: 10.1016/j.conb.2020.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/16/2020] [Accepted: 07/27/2020] [Indexed: 12/14/2022]
Abstract
Neural guidance mechanisms ensure the precise targeting and synaptogenesis events essential for normal circuit function. Neuronal growth cones encounter numerous attractive and repulsive cues as they navigate toward their intermediate and final targets; temporal and spatial regulation of these responses are critical for circuit assembly. Recent work highlights the complexity of these events throughout neural development and the multifaceted functions of a wide range of guidance cues. Here, we discuss recent studies that leverage advances in genetics, single cell tracing, transcriptomics and proteomics to further our understanding of the molecular mechanisms underlying neural guidance and overall circuit organization.
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Affiliation(s)
- Joelle M Dorskind
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Alex L Kolodkin
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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15
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Merk DJ, Zhou P, Cohen SM, Pazyra-Murphy MF, Hwang GH, Rehm KJ, Alfaro J, Reid CM, Zhao X, Park E, Xu PX, Chan JA, Eck MJ, Nazemi KJ, Harwell CC, Segal RA. The Eya1 Phosphatase Mediates Shh-Driven Symmetric Cell Division of Cerebellar Granule Cell Precursors. Dev Neurosci 2021; 42:170-186. [PMID: 33472197 DOI: 10.1159/000512976] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/10/2020] [Indexed: 12/14/2022] Open
Abstract
During neural development, stem and precursor cells can divide either symmetrically or asymmetrically. The transition between symmetric and asymmetric cell divisions is a major determinant of precursor cell expansion and neural differentiation, but the underlying mechanisms that regulate this transition are not well understood. Here, we identify the Sonic hedgehog (Shh) pathway as a critical determinant regulating the mode of division of cerebellar granule cell precursors (GCPs). Using partial gain and loss of function mutations within the Shh pathway, we show that pathway activation determines spindle orientation of GCPs, and that mitotic spindle orientation correlates with the mode of division. Mechanistically, we show that the phosphatase Eya1 is essential for implementing Shh-dependent GCP spindle orientation. We identify atypical protein kinase C (aPKC) as a direct target of Eya1 activity and show that Eya1 dephosphorylates a critical threonine (T410) in the activation loop. Thus, Eya1 inactivates aPKC, resulting in reduced phosphorylation of Numb and other components that regulate the mode of division. This Eya1-dependent cascade is critical in linking spindle orientation, cell cycle exit and terminal differentiation. Together these findings demonstrate that a Shh-Eya1 regulatory axis selectively promotes symmetric cell divisions during cerebellar development by coordinating spindle orientation and cell fate determinants.
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Affiliation(s)
- Daniel J Merk
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Pengcheng Zhou
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Samuel M Cohen
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Maria F Pazyra-Murphy
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Grace H Hwang
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Kristina J Rehm
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jose Alfaro
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Christopher M Reid
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Xuesong Zhao
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Eunyoung Park
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Pin-Xian Xu
- Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York, USA
| | - Jennifer A Chan
- Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Michael J Eck
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Kellie J Nazemi
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, USA
| | - Corey C Harwell
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA,
| | - Rosalind A Segal
- Department of Cancer Biology and Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
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16
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Zheng S, Huang W, Liu C, Xiao J, Wu R, Wang X, Cai Z, Wu K. Behavioral change and transcriptomics reveal the effects of 2, 2', 4, 4'-tetrabromodiphenyl ether exposure on neurodevelopmental toxicity to zebrafish (Danio rerio) in early life stage. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 752:141783. [PMID: 32890828 DOI: 10.1016/j.scitotenv.2020.141783] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/16/2020] [Accepted: 08/17/2020] [Indexed: 02/05/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants, and their residue in the environment may threaten the ecosystem and human health. The neurodevelopmental toxic effects of PBDEs have been verified in previous studies, but the mechanisms are still unclear. Behavioral analysis and transcriptomics were performed in this study to assess the neurodevelopmental toxic effects of PBDEs on zebrafish embryos and larvae, and the potential mechanisms. The embryos were collected after fertilization and exposed to control (0.05% DMSO), 10, 50, 100 (ug/L) 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) for 7 days. The locomotion parameters of larvae were recorded and analyzed by a behavioral analysis system (EthoVision XT, Noldus). Enrichment of functions and signaling pathways of differentially expressed genes (DEGs) were analyzed by GO and DAVID database. The comparison with the control group showed adverse developments such as low hatching rate, high mortality rate, alterative heart rate, and abnormal spontaneous tail coiling frequency of embryos (24hpf). For the zebrafish larvae, behavioral analyses results suggested decreased activities and movements of the treatment in the light-dark period at 120, 144 and 168hpf, especially the 50 and 100μg/L groups. The affected functions included steroid hormone regulation, neuro regulation, circadian regulation, cardioblast differentiation, immune-related regulation. The enrichment of KEGG pathways were Hedgehog signaling (Shh), Toll-like receptor signaling, FoxO signaling, and Steroid biosynthesis pathway. Hedgehog signaling pathway was further verified via RT-qPCR for its major role in the development of neurogenesis. The mRNA levels of Shh pathway indicated the inhibition of Shh signal in our study since shha, patched1, gli1 and gli2 genes were significantly down-regulated. In summary, PBDEs might influence the neurodevelopment of zebrafish in the early life stage by multiple toxic signaling pathways alteration.
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Affiliation(s)
- Shukai Zheng
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Wenlong Huang
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Caixia Liu
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Jiefeng Xiao
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Ruotong Wu
- School of Life Science, Xiamen University, Xiamen 361102, Fujian, China
| | - Xin Wang
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Zemin Cai
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China
| | - Kusheng Wu
- Department of Preventive Medicine, Shantou University Medical College, Shantou 515041, Guangdong, China.
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17
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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: 30] [Impact Index Per Article: 7.5] [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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18
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Klein R, Pasterkamp RJ. Recent advances in inter-cellular interactions during neural circuit assembly. Curr Opin Neurobiol 2021; 69:25-32. [PMID: 33383489 DOI: 10.1016/j.conb.2020.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022]
Abstract
Neural circuit assembly is regulated by inter-cellular interactions involving secreted and surface-tethered guidance molecules. Here, we review recent progress in our understanding of their mechanisms-of-action and biological effects. We discuss mechanisms through which the secreted cue Netrin-1 regulates neuron migration and highlight novel roles for axon-derived secreted guidance cues. We cover recent structural work at atomic resolution that provides new insights into the activation mechanisms of axon guidance receptors and into protein complexes containing cell adhesion molecules, such as Teneurin (Ten), Latrophilin (Lphn) and FLRT. Ten-Ten homophilic, Ten-Lphn heterophilic, and Ten-Lphn-FLRT tripartite complexes seem to elicit distinct context-dependent cellular responses. Seemingly opposite responses can also be triggered by the Eph/ephrin signaling system. Here, recent work provides a simple mechanism for the decision of forming a new synapse versus rejection of the pre-synaptic partner. These studies identify novel regulatory mechanisms and biological functions that will apply generally in developing neural systems.
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Affiliation(s)
- Rüdiger Klein
- Department Molecules-Signaling-Development, Max Planck Institute of Neurobiology, Am Klopferspitz 18, 82152 Martinsried, Germany.
| | - Ronald Jeroen Pasterkamp
- Department of Translational Neuroscience, University Medical Center (UMC) Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
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19
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Abstract
Retinal ganglion cells (RGCs) serve as a crucial communication channel from the retina to the brain. In the adult, these cells receive input from defined sets of presynaptic partners and communicate with postsynaptic brain regions to convey features of the visual scene. However, in the developing visual system, RGC interactions extend beyond their synaptic partners such that they guide development before the onset of vision. In this Review, we summarize our current understanding of how interactions between RGCs and their environment influence cellular targeting, migration and circuit maturation during visual system development. We describe the roles of RGC subclasses in shaping unique developmental responses within the retina and at central targets. Finally, we highlight the utility of RNA sequencing and genetic tools in uncovering RGC type-specific roles during the development of the visual system.
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Affiliation(s)
- Shane D'Souza
- The Visual Systems Group, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Center for Chronobiology, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Molecular and Developmental Biology Graduate Program, University of Cincinnati, College of Medicine, Cincinnati, OH 45229, USA
| | - Richard A Lang
- The Visual Systems Group, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Center for Chronobiology, Abrahamson Pediatric Eye Institute, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
- Department of Ophthalmology, University of Cincinnati, College of Medicine, Cincinnati, OH 45229, USA
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20
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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: 22] [Impact Index Per Article: 4.4] [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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21
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McCormick LE, Gupton SL. Mechanistic advances in axon pathfinding. Curr Opin Cell Biol 2020; 63:11-19. [PMID: 31927278 DOI: 10.1016/j.ceb.2019.12.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/02/2019] [Accepted: 12/02/2019] [Indexed: 02/08/2023]
Abstract
The development of a functional nervous system entails establishing connectivity between appropriate synaptic partners. During axonal pathfinding, the developing axon navigates through the extracellular environment, extending toward postsynaptic targets. In the early 1900s, Ramon y Cajal suggested that the growth cone, a specialized, dynamic, and cytoskeletal-rich structure at the tip of the extending axon, is guided by chemical cues in the extracellular environment. A century of work supports this hypothesis and introduced myriad guidance cues and receptors that promote a variety of growth cone behaviors including extension, pause, collapse, retraction, turning, and branching. Here, we highlight research from the last two years regarding pathways implicated in axon pathfinding.
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Affiliation(s)
- Laura E McCormick
- UNC Department of Cell Biology and Physiology, 111 Mason Farm Road, Chapel Hill, NC, 27599, USA
| | - Stephanie L Gupton
- UNC Department of Cell Biology and Physiology, 111 Mason Farm Road, Chapel Hill, NC, 27599, USA; UNC Neuroscience Center, 115 Mason Farm Road, Chapel Hill, NC, 27599, USA; UNC Lineberger Comprehensive Cancer Center, 101 Manning Dr, Chapel Hill, NC, 27514, USA.
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22
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Ferent J, Constable S, Gigante ED, Yam PT, Mariani LE, Legué E, Liem KF, Caspary T, Charron F. The Ciliary Protein Arl13b Functions Outside of the Primary Cilium in Shh-Mediated Axon Guidance. Cell Rep 2019; 29:3356-3366.e3. [PMID: 31825820 PMCID: PMC6927553 DOI: 10.1016/j.celrep.2019.11.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/19/2019] [Accepted: 11/04/2019] [Indexed: 12/19/2022] Open
Abstract
The small GTPase Arl13b is enriched in primary cilia and regulates Sonic hedgehog (Shh) signaling. During neural development, Shh controls patterning and proliferation through a canonical, transcription-dependent pathway that requires the primary cilium. Additionally, Shh controls axon guidance through a non-canonical, transcription-independent pathway whose connection to the primary cilium is unknown. Here we show that inactivation of Arl13b results in defective commissural axon guidance in vivo. In vitro, we demonstrate that Arl13b functions autonomously in neurons for their Shh-dependent guidance response. We detect Arl13b protein in axons and growth cones, far from its well-established ciliary enrichment. To test whether Arl13b plays a non-ciliary function, we used an engineered, cilia-localization-deficient Arl13b variant and found that it was sufficient to mediate Shh axon guidance in vitro and in vivo. Together, these results indicate that, in addition to its ciliary role in canonical Shh signaling, Arl13b plays a cilia-independent role in Shh-mediated axon guidance.
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Affiliation(s)
- Julien Ferent
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC H2W 1R7, Canada; Department of Neuroscience, University of Montreal, Montreal, QC H3T 1J4, Canada
| | - Sandii Constable
- Department of Human Genetics, 615 Michael St., Suite 301, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Eduardo D Gigante
- Department of Human Genetics, 615 Michael St., Suite 301, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Patricia T Yam
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC H2W 1R7, Canada
| | - Laura E Mariani
- Department of Human Genetics, 615 Michael St., Suite 301, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Emilie Legué
- Vertebrate Developmental Biology Program and Department of Pediatrics, Yale School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Karel F Liem
- Vertebrate Developmental Biology Program and Department of Pediatrics, Yale School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Tamara Caspary
- Department of Human Genetics, 615 Michael St., Suite 301, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Frédéric Charron
- Montreal Clinical Research Institute (IRCM), 110 Pine Avenue West, Montreal, QC H2W 1R7, Canada; Department of Neuroscience, University of Montreal, Montreal, QC H3T 1J4, Canada; Department of Anatomy and Cell Biology, Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada; Department of Medicine, University of Montreal, Montreal, QC H3T 1J4, Canada.
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23
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Sasai N, Toriyama M, Kondo T. Hedgehog Signal and Genetic Disorders. Front Genet 2019; 10:1103. [PMID: 31781166 PMCID: PMC6856222 DOI: 10.3389/fgene.2019.01103] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 10/11/2019] [Indexed: 12/12/2022] Open
Abstract
The hedgehog (Hh) family comprises sonic hedgehog (Shh), Indian hedgehog (Ihh), and desert hedgehog (Dhh), which are versatile signaling molecules involved in a wide spectrum of biological events including cell differentiation, proliferation, and survival; establishment of the vertebrate body plan; and aging. These molecules play critical roles from embryogenesis to adult stages; therefore, alterations such as abnormal expression or mutations of the genes involved and their downstream factors cause a variety of genetic disorders at different stages. The Hh family involves many signaling mediators and functions through complex mechanisms, and achieving a comprehensive understanding of the entire signaling system is challenging. This review discusses the signaling mediators of the Hh pathway and their functions at the cellular and organismal levels. We first focus on the roles of Hh signaling mediators in signal transduction at the cellular level and the networks formed by these factors. Then, we analyze the spatiotemporal pattern of expression of Hh pathway molecules in tissues and organs, and describe the phenotypes of mutant mice. Finally, we discuss the genetic disorders caused by malfunction of Hh signaling-related molecules in humans.
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Affiliation(s)
- Noriaki Sasai
- Developmental Biomedical Science, Division of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Japan
| | - Michinori Toriyama
- Systems Neurobiology and Medicine, Division of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Japan
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Japan
| | - Toru Kondo
- Division of Stem Cell Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
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24
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Endocytic Adaptor Proteins in Health and Disease: Lessons from Model Organisms and Human Mutations. Cells 2019; 8:cells8111345. [PMID: 31671891 PMCID: PMC6912373 DOI: 10.3390/cells8111345] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 12/11/2022] Open
Abstract
Cells need to exchange material and information with their environment. This is largely achieved via cell-surface receptors which mediate processes ranging from nutrient uptake to signaling responses. Consequently, their surface levels have to be dynamically controlled. Endocytosis constitutes a powerful mechanism to regulate the surface proteome and to recycle vesicular transmembrane proteins that strand at the plasma membrane after exocytosis. For efficient internalization, the cargo proteins need to be linked to the endocytic machinery via adaptor proteins such as the heterotetrameric endocytic adaptor complex AP-2 and a variety of mostly monomeric endocytic adaptors. In line with the importance of endocytosis for nutrient uptake, cell signaling and neurotransmission, animal models and human mutations have revealed that defects in these adaptors are associated with several diseases ranging from metabolic disorders to encephalopathies. This review will discuss the physiological functions of the so far known adaptor proteins and will provide a comprehensive overview of their links to human diseases.
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