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Sadamitsu K, Yanagi K, Hasegawa Y, Murakami Y, Low SE, Ooshima D, Matsubara Y, Okamoto N, Kaname T, Hirata H. A novel homozygous variant of the PIGK gene caused by paternal disomy in a patient with neurodevelopmental disorder, cerebellar atrophy, and seizures. J Hum Genet 2024:10.1038/s10038-024-01264-3. [PMID: 38902431 DOI: 10.1038/s10038-024-01264-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/27/2024] [Accepted: 05/30/2024] [Indexed: 06/22/2024]
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins are located at the cell surface by a covalent attachment between protein and GPI embedded in the plasma membrane. This attachment is catalyzed by GPI transamidase comprising five subunits (PIGK, PIGS, PIGT, PIGU, and GPAA1) in the endoplasmic reticulum. Loss of either subunit of GPI transamidase eliminates cell surface localization of GPI-anchored proteins. In humans, pathogenic variants in either subunit of GPI transamidase cause neurodevelopmental disorders. However, how the loss of GPI-anchored proteins triggers neurodevelopmental defects remains largely unclear. Here, we identified a novel homozygous variant of PIGK, NM_005482:c.481A > G,p. (Met161Val), in a Japanese female patient with neurodevelopmental delay, hypotonia, cerebellar atrophy, febrile seizures, hearing loss, growth impairment, dysmorphic facial features, and brachydactyly. The missense variant was found heterozygous in her father, but not in her mother. Zygosity analysis revealed that the homozygous PIGK variant in the patient was caused by paternal isodisomy. Rescue experiments using PIGK-deficient CHO cells revealed that the p.Met161Val variant of PIGK reduced GPI transamidase activity. Rescue experiments using pigk mutant zebrafish confirmed that the p.Met161Val variant compromised PIGK function in tactile-evoked motor response. We also demonstrated that axonal localization of voltage-gated sodium channels and concomitant generation of action potentials were impaired in pigk-deficient neurons in zebrafish, suggesting a link between GPI-anchored proteins and neuronal defects. Taken together, the missense p.Met161Val variant of PIGK is a novel pathogenic variant that causes the neurodevelopmental disorder.
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Affiliation(s)
- Kenichiro Sadamitsu
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Kumiko Yanagi
- Department of Genome Medicine, National Center for Child Health and Development, Tokyo, 157-8535, Japan
| | - Yuiko Hasegawa
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Izumi, 594-1101, Japan
| | - Yoshiko Murakami
- Laboratory of Immunoglycobiology, Research Institute for Microbial Diseases, Osaka University, Suita, 565-0871, Japan
| | - Sean E Low
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Daikun Ooshima
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan
| | - Yoichi Matsubara
- National Center for Child Health and Development, Tokyo, 157-8535, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Izumi, 594-1101, Japan
| | - Tadashi Kaname
- Department of Genome Medicine, National Center for Child Health and Development, Tokyo, 157-8535, Japan.
| | - Hiromi Hirata
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan.
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2
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Lee AS, Ayers LJ, Kosicki M, Chan WM, Fozo LN, Pratt BM, Collins TE, Zhao B, Rose MF, Sanchis-Juan A, Fu JM, Wong I, Zhao X, Tenney AP, Lee C, Laricchia KM, Barry BJ, Bradford VR, Lek M, MacArthur DG, Lee EA, Talkowski ME, Brand H, Pennacchio LA, Engle EC. A cell type-aware framework for nominating non-coding variants in Mendelian regulatory disorders. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.12.22.23300468. [PMID: 38234731 PMCID: PMC10793524 DOI: 10.1101/2023.12.22.23300468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Unsolved Mendelian cases often lack obvious pathogenic coding variants, suggesting potential non-coding etiologies. Here, we present a single cell multi-omic framework integrating embryonic mouse chromatin accessibility, histone modification, and gene expression assays to discover cranial motor neuron (cMN) cis-regulatory elements and subsequently nominate candidate non-coding variants in the congenital cranial dysinnervation disorders (CCDDs), a set of Mendelian disorders altering cMN development. We generated single cell epigenomic profiles for ~86,000 cMNs and related cell types, identifying ~250,000 accessible regulatory elements with cognate gene predictions for ~145,000 putative enhancers. Seventy-five percent of elements (44 of 59) validated in an in vivo transgenic reporter assay, demonstrating that single cell accessibility is a strong predictor of enhancer activity. Applying our cMN atlas to 899 whole genome sequences from 270 genetically unsolved CCDD pedigrees, we achieved significant reduction in our variant search space and nominated candidate variants predicted to regulate known CCDD disease genes MAFB, PHOX2A, CHN1, and EBF3 - as well as new candidates in recurrently mutated enhancers through peak- and gene-centric allelic aggregation. This work provides novel non-coding variant discoveries of relevance to CCDDs and a generalizable framework for nominating non-coding variants of potentially high functional impact in other Mendelian disorders.
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Affiliation(s)
- Arthur S Lee
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA
- Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Lauren J Ayers
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Michael Kosicki
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Wai-Man Chan
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Howard Hughes Medical Institute, Chevy Chase, MD
| | - Lydia N Fozo
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Brandon M Pratt
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Thomas E Collins
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Boxun Zhao
- Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA
| | - Matthew F Rose
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Department of Pathology, Boston Children's Hospital, Boston, MA
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
- Medical Genetics Training Program, Harvard Medical School, Boston, MA
| | - Alba Sanchis-Juan
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA
| | - Jack M Fu
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Isaac Wong
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA
| | - Xuefang Zhao
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Alan P Tenney
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Cassia Lee
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Harvard College, Cambridge, MA
| | - Kristen M Laricchia
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Brenda J Barry
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Howard Hughes Medical Institute, Chevy Chase, MD
| | - Victoria R Bradford
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Monkol Lek
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
| | - Daniel G MacArthur
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Centre for Population Genomics, Garvan Institute of Medical Research and UNSW Sydney, Sydney, NSW, Australia
- Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - Eunjung Alice Lee
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA
- Department of Genetics, Harvard Medical School, Boston, MA
| | - Michael E Talkowski
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Harrison Brand
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA
- Pediatric Surgical Research Laboratories, Massachusetts General Hospital, Boston, MA
| | - Len A Pennacchio
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA
| | - Elizabeth C Engle
- Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA
- Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA
- Howard Hughes Medical Institute, Chevy Chase, MD
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA
- Medical Genetics Training Program, Harvard Medical School, Boston, MA
- Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, MA
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Cintrón-Rivera LG, Burns N, Patel R, Plavicki JS. Exposure to the aryl hydrocarbon receptor agonist dioxin disrupts formation of the muscle, nerves, and vasculature in the developing jaw. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 337:122499. [PMID: 37660771 DOI: 10.1016/j.envpol.2023.122499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/14/2023] [Accepted: 08/31/2023] [Indexed: 09/05/2023]
Abstract
Human exposure to environmental pollutants can disrupt embryonic development and impact juvenile and adult health outcomes by adversely affecting cell and organ function. Notwithstanding, environmental contamination continues to increase due to industrial development, insufficient regulations, and the mobilization of pollutants as a result of extreme weather events. Dioxins are a class of structurally related persistent organic pollutants that are highly toxic, carcinogenic, and teratogenic. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most potent dioxin compound and has been shown to induce toxic effects in developing organisms by activating the aryl hydrocarbon receptor (AHR), a ligand activated transcription factor targeted by multiple persistent organic pollutants. Contaminant-induced AHR activation results in malformations of the craniofacial cartilages and neurocranium; however, the mechanisms mediating these phenotypes are not well understood. In this study, we utilized the optically transparent zebrafish model to elucidate novel cellular targets and potential transcriptional targets underlying TCDD-induced craniofacial malformations. To this end, we exposed zebrafish embryos at 4 h post fertilization to TCDD and employed a mixed-methods approach utilizing immunohistochemistry staining, transgenic reporter lines, fixed and in vivo confocal imaging, and timelapse microscopy to determine the targets mediating TCDD-induced craniofacial phenotypes. Our data indicate that embryonic TCDD exposure reduced jaw and pharyngeal arch Sox10+ chondrocytes and Tcf21+ pharyngeal mesoderm progenitors. Exposure to TCDD correspondingly led to a reduction in collagen type II deposition in Sox10+ domains. Embryonic TCDD exposure impaired development of tissues derived from or guided by Tcf21+ progenitors, namely: nerves, muscle, and vasculature. Specifically, TCDD exposure disrupted development of the hyoid and mandibular arch muscles, decreased neural innervation of the jaw, resulted in compression of cranial nerves V and VII, and led to jaw vasculature malformations. Collectively, these findings reveal novel structural targets and potential transcriptional targets of TCDD-induced toxicity, showcasing how contaminant exposures lead to congenital craniofacial malformations.
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Affiliation(s)
- Layra G Cintrón-Rivera
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship St, Providence, RI, 02903, USA
| | - Nicole Burns
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship St, Providence, RI, 02903, USA
| | - Ratna Patel
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship St, Providence, RI, 02903, USA
| | - Jessica S Plavicki
- Department of Pathology and Laboratory Medicine, Brown University, 70 Ship St, Providence, RI, 02903, USA.
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4
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Walker LJ, Guevara C, Kawakami K, Granato M. Target-selective vertebrate motor axon regeneration depends on interaction with glial cells at a peripheral nerve plexus. PLoS Biol 2023; 21:e3002223. [PMID: 37590333 PMCID: PMC10464982 DOI: 10.1371/journal.pbio.3002223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 08/29/2023] [Accepted: 06/28/2023] [Indexed: 08/19/2023] Open
Abstract
A critical step for functional recovery from peripheral nerve injury is for regenerating axons to connect with their pre-injury targets. Reestablishing pre-injury target specificity is particularly challenging for limb-innervating axons as they encounter a plexus, a network where peripheral nerves converge, axons from different nerves intermingle, and then re-sort into target-specific bundles. Here, we examine this process at a plexus located at the base of the zebrafish pectoral fin, equivalent to tetrapod forelimbs. Using live cell imaging and sparse axon labeling, we find that regenerating motor axons from 3 nerves coalesce into the plexus. There, they intermingle and sort into distinct branches, and then navigate to their original muscle domains with high fidelity that restores functionality. We demonstrate that this regeneration process includes selective retraction of mistargeted axons, suggesting active correction mechanisms. Moreover, we find that Schwann cells are enriched and associate with axons at the plexus, and that Schwann cell ablation during regeneration causes profound axonal mistargeting. Our data provide the first real-time account of regenerating vertebrate motor axons navigating a nerve plexus and reveal a previously unappreciated role for Schwann cells to promote axon sorting at a plexus during regeneration.
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Affiliation(s)
- Lauren J. Walker
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Camilo Guevara
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, and Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, Japan
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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5
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Walker LJ, Guevara C, Kawakami K, Granato M. A glia cell dependent mechanism at a peripheral nerve plexus critical for target-selective axon regeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.05.522786. [PMID: 36712008 PMCID: PMC9881934 DOI: 10.1101/2023.01.05.522786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A critical step for functional recovery from peripheral nerve injury is for regenerating axons to connect with their pre-injury targets. Reestablishing pre-injury target specificity is particularly challenging for limb-innervating axons as they encounter a plexus, a network where peripheral nerves converge, axons from different nerves intermingle, and then re-sort into target-specific bundles. Here, we examine this process at a plexus located at the base of the zebrafish pectoral fin, equivalent to tetrapod forelimbs. Using live cell imaging and sparse axon labeling, we find that regenerating motor axons from three nerves coalesce into the plexus. There, they intermingle and sort into distinct branches, and then navigate to their original muscle domains with high fidelity that restores functionality. We demonstrate that this regeneration process includes selective retraction of mistargeted axons, suggesting active correction mechanisms. Moreover, we find that Schwann cells are enriched and associate with axons at the plexus, and that Schwann cell ablation during regeneration causes profound axonal mistargeting. Our data provide the first real time account of regenerating vertebrate motor axons navigating a nerve plexus and reveal a previously unappreciated role for Schwann cells to promote axon sorting at a plexus during regeneration.
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Affiliation(s)
- Lauren J Walker
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Camilo Guevara
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, and Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka 411-8540, Japan
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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6
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Lysko DE, Talbot WS. Unmyelinated sensory neurons use Neuregulin signals to promote myelination of interneurons in the CNS. Cell Rep 2022; 41:111669. [PMID: 36384112 PMCID: PMC9719401 DOI: 10.1016/j.celrep.2022.111669] [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: 04/01/2022] [Revised: 09/06/2022] [Accepted: 10/25/2022] [Indexed: 11/17/2022] Open
Abstract
The signaling mechanisms neurons use to modulate myelination of circuits in the central nervous system (CNS) are only partly understood. Through analysis of isoform-specific neuregulin1 (nrg1) mutants in zebrafish, we demonstrate that nrg1 type II is an important regulator of myelination of two classes of spinal cord interneurons. Surprisingly, nrg1 type II expression is prominent in unmyelinated Rohon-Beard sensory neurons, whereas myelination of neighboring interneurons is reduced in nrg1 type II mutants. Cell-type-specific loss-of-function studies indicate that nrg1 type II is required in Rohon-Beard neurons to signal to other neurons, not oligodendrocytes, to modulate spinal cord myelination. Together, our data support a model in which unmyelinated neurons express Nrg1 type II proteins to regulate myelination of neighboring neurons, a mode of action that may coordinate the functions of unmyelinated and myelinated neurons in the CNS.
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Affiliation(s)
- Daniel E Lysko
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - William S Talbot
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
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7
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Abstract
Motor circuits develop in sequence from those governing fast movements to those governing slow. Here we examine whether upstream sensory circuits are organized by similar principles. Using serial-section electron microscopy in larval zebrafish, we generated a complete map of the gravity-sensing (utricular) system spanning from the inner ear to the brainstem. We find that both sensory tuning and developmental sequence are organizing principles of vestibular topography. Patterned rostrocaudal innervation from hair cells to afferents creates an anatomically inferred directional tuning map in the utricular ganglion, forming segregated pathways for rostral and caudal tilt. Furthermore, the mediolateral axis of the ganglion is linked to both developmental sequence and neuronal temporal dynamics. Early-born pathways carrying phasic information preferentially excite fast escape circuits, whereas later-born pathways carrying tonic signals excite slower postural and oculomotor circuits. These results demonstrate that vestibular circuits are organized by tuning direction and dynamics, aligning them with downstream motor circuits and behaviors. How sensory systems are organized during development remains unclear. Here, the authors used electron microscopy to examine the gravity-sensing system in zebrafish, finding that directional tuning and developmental age are organizing principles of the transformation from vestibular sensation to motor control.
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Closser M, Guo Y, Wang P, Patel T, Jang S, Hammelman J, De Nooij JC, Kopunova R, Mazzoni EO, Ruan Y, Gifford DK, Wichterle H. An expansion of the non-coding genome and its regulatory potential underlies vertebrate neuronal diversity. Neuron 2022; 110:70-85.e6. [PMID: 34727520 PMCID: PMC8738133 DOI: 10.1016/j.neuron.2021.10.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/25/2021] [Accepted: 10/06/2021] [Indexed: 01/07/2023]
Abstract
Proper assembly and function of the nervous system requires the generation of a uniquely diverse population of neurons expressing a cell-type-specific combination of effector genes that collectively define neuronal morphology, connectivity, and function. How countless partially overlapping but cell-type-specific patterns of gene expression are controlled at the genomic level remains poorly understood. Here we show that neuronal genes are associated with highly complex gene regulatory systems composed of independent cell-type- and cell-stage-specific regulatory elements that reside in expanded non-coding genomic domains. Mapping enhancer-promoter interactions revealed that motor neuron enhancers are broadly distributed across the large chromatin domains. This distributed regulatory architecture is not a unique property of motor neurons but is employed throughout the nervous system. The number of regulatory elements increased dramatically during the transition from invertebrates to vertebrates, suggesting that acquisition of new enhancers might be a fundamental process underlying the evolutionary increase in cellular complexity.
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Affiliation(s)
- Michael Closser
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Yuchun Guo
- Computer Science and Artificial Intelligence Laboratory, MIT, Cambridge, MA 02139, USA
| | - Ping Wang
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06030, USA
| | - Tulsi Patel
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Sumin Jang
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jennifer Hammelman
- Computer Science and Artificial Intelligence Laboratory, MIT, Cambridge, MA 02139, USA
| | - Joriene C De Nooij
- Department of Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Rachel Kopunova
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY 10032, USA
| | | | - Yijun Ruan
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06030, USA
| | - David K Gifford
- Computer Science and Artificial Intelligence Laboratory, MIT, Cambridge, MA 02139, USA.
| | - Hynek Wichterle
- Departments of Pathology and Cell Biology, Neuroscience, and Neurology, Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY 10032, USA.
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Haimson B, Hadas Y, Bernat N, Kania A, Daley MA, Cinnamon Y, Lev-Tov A, Klar A. Spinal lumbar dI2 interneurons contribute to stability of bipedal stepping. eLife 2021; 10:62001. [PMID: 34396953 PMCID: PMC8448531 DOI: 10.7554/elife.62001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 08/11/2021] [Indexed: 11/13/2022] Open
Abstract
Peripheral and intraspinal feedback is required to shape and update the output of spinal networks that execute motor behavior. We report that lumbar dI2 spinal interneurons in chicks receive synaptic input from afferents and premotor neurons. These interneurons innervate contralateral premotor networks in the lumbar and brachial spinal cord, and their ascending projections innervate the cerebellum. These findings suggest that dI2 neurons function as interneurons in local lumbar circuits, are involved in lumbo-brachial coupling, and that part of them deliver peripheral and intraspinal feedback to the cerebellum. Silencing of dI2 neurons leads to destabilized stepping in P8 hatchlings, with occasional collapses, variable step profiles and a wide-base walking gait, suggesting that dI2 neurons may contribute to the stabilization of the bipedal gait.
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Affiliation(s)
- Baruch Haimson
- Department of Medical Neurobiology,, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel, jerusalem, Israel
| | - Yoav Hadas
- Department of Medical Neurobiology,, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel, Jerusalem, Israel
| | - Nimrod Bernat
- Department of Medical Neurobiology,, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel, jerusalem, Israel
| | - Artur Kania
- Anatomy and Cell Biology, Institut de recherches cliniques de Montréal (IRCM), Montreal, Canada
| | - Monica A Daley
- Ecology and Evolutionary Biology, University of California, Irvine, Irvine, United States
| | - Yuval Cinnamon
- Institute of Animal Science Poultry and Aquaculture Sci. Dept, Institute of Animal Science Poultry and Aquaculture Sci. Dept. Agricultural Research Organization, The Volcani Center, Israel, Rehovot, Israel
| | - Aharon Lev-Tov
- Department of Medical Neurobiology,, IMRIC, Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel, Jerisalem, Israel
| | - Avihu Klar
- Medical Neurobiology, Hebrew University, Jerusalem, Israel
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10
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Pereira JD, DuBreuil DM, Devlin AC, Held A, Sapir Y, Berezovski E, Hawrot J, Dorfman K, Chander V, Wainger BJ. Human sensorimotor organoids derived from healthy and amyotrophic lateral sclerosis stem cells form neuromuscular junctions. Nat Commun 2021; 12:4744. [PMID: 34362895 PMCID: PMC8346474 DOI: 10.1038/s41467-021-24776-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/06/2021] [Indexed: 02/07/2023] Open
Abstract
Human induced pluripotent stem cells (iPSC) hold promise for modeling diseases in individual human genetic backgrounds and thus for developing precision medicine. Here, we generate sensorimotor organoids containing physiologically functional neuromuscular junctions (NMJs) and apply the model to different subgroups of amyotrophic lateral sclerosis (ALS). Using a range of molecular, genomic, and physiological techniques, we identify and characterize motor neurons and skeletal muscle, along with sensory neurons, astrocytes, microglia, and vasculature. Organoid cultures derived from multiple human iPSC lines generated from individuals with ALS and isogenic lines edited to harbor familial ALS mutations show impairment at the level of the NMJ, as detected by both contraction and immunocytochemical measurements. The physiological resolution of the human NMJ synapse, combined with the generation of major cellular cohorts exerting autonomous and non-cell autonomous effects in motor and sensory diseases, may prove valuable to understand the pathophysiological mechanisms of ALS.
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Affiliation(s)
- João D Pereira
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Daniel M DuBreuil
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Anna-Claire Devlin
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Aaron Held
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Yechiam Sapir
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Eugene Berezovski
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - James Hawrot
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Katherine Dorfman
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Vignesh Chander
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Brian J Wainger
- Department of Neurology, Sean M. Healey & AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA.
- Harvard Stem Cell Institute, Cambridge, MA, USA.
- Broad Institute of Harvard University and MIT, Cambridge, MA, USA.
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11
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Wu MY, Carbo-Tano M, Mirat O, Lejeune FX, Roussel J, Quan FB, Fidelin K, Wyart C. Spinal sensory neurons project onto the hindbrain to stabilize posture and enhance locomotor speed. Curr Biol 2021; 31:3315-3329.e5. [PMID: 34146485 DOI: 10.1016/j.cub.2021.05.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 03/12/2021] [Accepted: 05/19/2021] [Indexed: 12/11/2022]
Abstract
In the spinal cord, cerebrospinal fluid-contacting neurons (CSF-cNs) are GABAergic interoceptive sensory neurons that detect spinal curvature via a functional coupling with the Reissner fiber. This mechanosensory system has recently been found to be involved in spine morphogenesis and postural control but the underlying mechanisms are not fully understood. In zebrafish, CSF-cNs project an ascending and ipsilateral axon reaching two to six segments away. Rostralmost CSF-cNs send their axons ipsilaterally into the hindbrain, a brain region containing motor nuclei and reticulospinal neurons (RSNs), which send descending motor commands to spinal circuits. Until now, the synaptic connectivity of CSF-cNs has only been investigated in the spinal cord, where they synapse onto motor neurons and premotor excitatory interneurons. The identity of CSF-cN targets in the hindbrain and the behavioral relevance of these sensory projections from the spinal cord to the hindbrain are unknown. Here, we provide anatomical and molecular evidence that rostralmost CSF-cNs synapse onto the axons of large RSNs including Mauthner cells and V2a neurons. Functional anatomy and optogenetically assisted mapping reveal that rostral CSF-cNs also synapse onto the soma and dendrites of cranial motor neurons innervating hypobranchial muscles. During acousto-vestibular evoked escape responses, ablation of rostralmost CSF-cNs results in a weaker escape response with a decreased C-bend amplitude, lower speed, and deficient postural control. Our study demonstrates that spinal sensory feedback enhances speed and stabilizes posture, and reveals a novel spinal gating mechanism acting on the output of descending commands sent from the hindbrain to the spinal cord.
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Affiliation(s)
- Ming-Yue Wu
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Martin Carbo-Tano
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France.
| | - Olivier Mirat
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Francois-Xavier Lejeune
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Julian Roussel
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Feng B Quan
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Kevin Fidelin
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France
| | - Claire Wyart
- Sorbonne Université, Institut du Cerveau (ICM), Inserm U 1127, CNRS UMR 7225, 75013 Paris, France.
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12
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Beiriger A, Narayan S, Singh N, Prince V. Development and migration of the zebrafish rhombencephalic octavolateral efferent neurons. J Comp Neurol 2021; 529:1293-1307. [PMID: 32869305 PMCID: PMC8238524 DOI: 10.1002/cne.25021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/13/2020] [Accepted: 08/25/2020] [Indexed: 02/05/2023]
Abstract
In vertebrate animals, motor and sensory efferent neurons carry information from the central nervous system (CNS) to peripheral targets. These two types of efferent systems sometimes bear a close resemblance, sharing common segmental organization, axon pathways, and chemical messengers. Here, we focus on the development of the octavolateral efferent neurons (OENs) and their interactions with the closely-related facial branchiomotor neurons (FBMNs) in zebrafish. Using live-imaging approaches, we investigate the birth, migration, and projection patterns of OENs. We find that OENs are born in two distinct groups: a group of rostral efferent neurons (RENs) that arises in the fourth segment, or rhombomere (r4), of the hindbrain and a group of caudal efferent neurons (CENs) that arises in r5. Both RENs and CENs then migrate posteriorly through the hindbrain between 18 and 48 hrs postfertilization, alongside the r4-derived FBMNs. Like the FBMNs, migration of the r4-derived RENs depends on function of the segmental identity gene hoxb1a; unlike the FBMNs, however, both OEN populations move independently of prickle1b. Further, we investigate whether the previously described "pioneer" neuron that leads FBMN migration through the hindbrain is an r4-derived FBMN/REN or an r5-derived CEN. Our experiments verify that the pioneer is an r4-derived neuron and reaffirm its role in leading FBMN migration across the r4/5 border. In contrast, the r5-derived CENs migrate independently of the pioneer. Together, these results indicate that the mechanisms OENs use to navigate the hindbrain differ significantly from those employed by FBMNs.
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Affiliation(s)
- Anastasia Beiriger
- Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Sweta Narayan
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, USA
| | - Noor Singh
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, USA
| | - Victoria Prince
- Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, Illinois, USA
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, USA
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13
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Etchegaray E, Naville M, Volff JN, Haftek-Terreau Z. Transposable element-derived sequences in vertebrate development. Mob DNA 2021; 12:1. [PMID: 33407840 PMCID: PMC7786948 DOI: 10.1186/s13100-020-00229-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 12/15/2020] [Indexed: 12/14/2022] Open
Abstract
Transposable elements (TEs) are major components of all vertebrate genomes that can cause deleterious insertions and genomic instability. However, depending on the specific genomic context of their insertion site, TE sequences can sometimes get positively selected, leading to what are called "exaptation" events. TE sequence exaptation constitutes an important source of novelties for gene, genome and organism evolution, giving rise to new regulatory sequences, protein-coding exons/genes and non-coding RNAs, which can play various roles beneficial to the host. In this review, we focus on the development of vertebrates, which present many derived traits such as bones, adaptive immunity and a complex brain. We illustrate how TE-derived sequences have given rise to developmental innovations in vertebrates and how they thereby contributed to the evolutionary success of this lineage.
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Affiliation(s)
- Ema Etchegaray
- Institut de Genomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Superieure de Lyon, Universite Claude Bernard Lyon 1, 46 allee d'Italie, F-69364, Lyon, France.
| | - Magali Naville
- Institut de Genomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Superieure de Lyon, Universite Claude Bernard Lyon 1, 46 allee d'Italie, F-69364, Lyon, France
| | - Jean-Nicolas Volff
- Institut de Genomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Superieure de Lyon, Universite Claude Bernard Lyon 1, 46 allee d'Italie, F-69364, Lyon, France
| | - Zofia Haftek-Terreau
- Institut de Genomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Superieure de Lyon, Universite Claude Bernard Lyon 1, 46 allee d'Italie, F-69364, Lyon, France
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14
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Neuronal Circuits That Control Rhythmic Pectoral Fin Movements in Zebrafish. J Neurosci 2020; 40:6678-6690. [PMID: 32703904 DOI: 10.1523/jneurosci.1484-20.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/14/2020] [Accepted: 07/16/2020] [Indexed: 12/12/2022] Open
Abstract
The most basic form of locomotion in limbed vertebrates consists of alternating activities of the flexor and extensor muscles within each limb coupled with left/right limb alternation. Although larval zebrafish are not limbed, their pectoral fin movements exhibit the following fundamental aspects of this basic movement: abductor/adductor alternation (corresponding to flexor/extensor alternation) and left/right fin alternation. Because of the simplicity of their movements and the compact neural organization of their spinal cords, zebrafish can serve as a good model to identify the neuronal networks of the central pattern generator (CPG) that controls rhythmic appendage movements. Here, we set out to investigate neuronal circuits underlying rhythmic pectoral fin movements in larval zebrafish, using transgenic fish that specifically express GFP in abductor or adductor motor neurons (MNs) and candidate CPG neurons. First, we showed that spiking activities of abductor and adductor MNs were essentially alternating. Second, both abductor and adductor MNs received rhythmic excitatory and inhibitory synaptic inputs in their active and inactive phases, respectively, indicating that the MN spiking activities are controlled in a push-pull manner. Further, we obtained the following evidence that dmrt3a-expressing commissural inhibitory neurons are involved in regulating the activities of abductor MNs: (1) strong inhibitory synaptic connections were found from dmrt3a neurons to abductor MNs; and (2) ablation of dmrt3a neurons shifted the spike timing of abductor MNs. Thus, in this simple system of abductor/adductor alternation, the last-order inhibitory inputs originating from the contralaterally located neurons play an important role in controlling the firing timings of MNs.SIGNIFICANCE STATEMENT Pectoral fin movements in larval zebrafish exhibit fundamental aspects of basic rhythmic appendage movement: alternation of the abductor and adductor (corresponding to flexor-extensor alternation) coupled with left-right alternation. We set out to investigate the neuronal circuits underlying rhythmic pectoral fin movements in larval zebrafish. We showed that both abductor and adductor MNs received rhythmic excitatory and inhibitory synaptic inputs in their active and inactive phases, respectively. This indicates that MN activities are controlled in a push-pull manner. We further obtained evidence that dmrt3a-expressing commissural inhibitory neurons exert an inhibitory effect on abductor MNs. The current study marks the first step toward the identification of central pattern generator organization for rhythmic fin movements.
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15
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Williams K, Ribera AB. Long-lived zebrafish Rohon-Beard cells. Dev Biol 2020; 464:45-52. [PMID: 32473165 DOI: 10.1016/j.ydbio.2020.05.003] [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: 11/04/2019] [Revised: 05/13/2020] [Accepted: 05/13/2020] [Indexed: 10/24/2022]
Abstract
During normal development of the nervous system, extensive neuronal proliferation as well as death occurs. The extent of development death varies considerably between neuronal populations from little to almost 100%. Early born somatosensory neurons, known as Rohon-Beard cells, have served as an example of neurons that disappear during early developmental stages, presumably as their function is taken over by later developing dorsal root ganglion neurons. However, recent studies have raised questions about the extent to which zebrafish Rohon-Beard cells die during embryogenesis. While Rohon-Beard cells have distinguishing morphological features during embryonic stages development, they subsequently undergo substantial changes in their shape, size and position that hinder their unambiguous identification at later stages. To overcome this obstacle, we identify Rohon-Beard cells at one day, and using a combination of mosaic and stable transgenic labeling and repeated observation, follow them for 13-16 days post fertilization. We find that about 40% survive to late larval stages. Our studies also reveal that Rohon-Beard cells display an unusual repertoire of cell death properties. At one day, about 25% Rohon-Beard cells expose phosphatidyl serine at the surface membrane, but less than one Rohon-Beard cell/embryo expresses activated-caspase-3. Further, the temporal delay between detection of cell death markers and loss of the soma ranges from <one to several days. The fact many Rohon-Beard cells survive for several weeks raises questions about potential unrecognized roles for Rohon-Beard cells in larval zebrafish.
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Affiliation(s)
- Kristina Williams
- Department of Physiology and Biophysics, University of Colorado School of Medicine, 12800 E. 19th Avenue, RC1N-7129, Aurora, CO, 80045, USA
| | - Angeles B Ribera
- Department of Physiology and Biophysics, University of Colorado School of Medicine, 12800 E. 19th Avenue, RC1N-7129, Aurora, CO, 80045, USA.
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16
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CBP and p300 coactivators contribute to the maintenance of Isl1 expression by the Onecut transcription factors in embryonic spinal motor neurons. Mol Cell Neurosci 2019; 101:103411. [PMID: 31648029 DOI: 10.1016/j.mcn.2019.103411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 08/14/2019] [Accepted: 09/11/2019] [Indexed: 11/24/2022] Open
Abstract
Onecut transcription factors are required to maintain Islet1 (Isl1) expression in developing spinal motor neurons (MNs), and this process is critical for proper MN differentiation. However, the mechanisms whereby OC stimulate Isl1 expression remain unknown. CREB-binding protein (CBP) and p300 paralogs are transcriptional coactivators that interact with OC proteins in hepatic cells. In the embryonic spinal cord, CBP and p300 play key roles in neurogenesis and MN differentiation. Here, using chromatin immunoprecipitation and in ovo electroporation in chicken spinal cord, we provide evidence that CBP and p300 contribute to the regulation of Isl1 expression by the OC factors in embryonic spinal MNs. CBP and p300 are detected on the CREST2 enhancer of Isl1 where OC factors are also bound. Inhibition of CBP and p300 activity inhibits activation of the CREST2 enhancer and prevents the stimulation of Isl1 expression by the OC factors. These observations suggest that CBP and p300 coactivators cooperate with OC factors to maintain Isl1 expression in postmitotic MNs.
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17
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Baeuml SW, Biechl D, Wullimann MF. Adult islet1 Expression Outlines Ventralized Derivatives Along Zebrafish Neuraxis. Front Neuroanat 2019; 13:19. [PMID: 30863287 PMCID: PMC6399416 DOI: 10.3389/fnana.2019.00019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/01/2019] [Indexed: 01/16/2023] Open
Abstract
Signals issued by dorsal roof and ventral floor plates, respectively, underlie the major patterning process of dorsalization and ventralization during vertebrate neural tube development. The ventrally produced morphogen Sonic hedgehog (SHH) is crucial for vertebrate hindbrain and spinal motor neuron development. One diagnostic gene for motor neurons is the LIM/homeodomain gene islet1, which has additional ventral expression domains extending into mid- and forebrain. In order to corroborate motor neuron development and, in particular, to improve on the identification of poorly documented zebrafish forebrain islet1 populations, we studied adult brains of transgenic islet1-GFP zebrafish (3 and 6 months). This molecular neuroanatomical analysis was supported by immunostaining these brains for tyrosine hydroxylase (TH) or choline acetyltransferase (ChAT), respectively, revealing zebrafish catecholaminergic and cholinergic neurons. The present analysis of ChAT and islet1-GFP label confirms ongoing adult expression of islet1 in zebrafish (basal plate) midbrain, hindbrain, and spinal motor neurons. In contrast, non-motor cholinergic systems lack islet1 expression. Additional presumed basal plate islet1 positive systems are described in detail, aided by TH staining which is particularly informative in the diencephalon. Finally, alar plate zebrafish forebrain systems with islet1 expression are described (i.e., thalamus, preoptic region, and subpallium). We conclude that adult zebrafish continue to express islet1 in the same brain systems as in the larva. Further, pending functional confirmation we hypothesize that the larval expression of sonic hedgehog (shh) might causally underlie much of adult islet1 expression because it explains findings beyond ventrally located systems, for example regarding shh expression in the zona limitans intrathalamica and correlated islet1-GFP expression in the thalamus.
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Affiliation(s)
- Stephan W Baeuml
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Daniela Biechl
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Mario F Wullimann
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
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18
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Mastrodonato V, Beznoussenko G, Mironov A, Ferrari L, Deflorian G, Vaccari T. A genetic model of CEDNIK syndrome in zebrafish highlights the role of the SNARE protein Snap29 in neuromotor and epidermal development. Sci Rep 2019; 9:1211. [PMID: 30718891 PMCID: PMC6361908 DOI: 10.1038/s41598-018-37780-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/06/2018] [Indexed: 12/25/2022] Open
Abstract
Homozygous mutations in SNAP29, encoding a SNARE protein mainly involved in membrane fusion, cause CEDNIK (Cerebral Dysgenesis, Neuropathy, Ichthyosis and Keratoderma), a rare congenital neurocutaneous syndrome associated with short life expectancy, whose pathogenesis is unclear. Here, we report the analysis of the first genetic model of CEDNIK in zebrafish. Strikingly, homozygous snap29 mutant larvae display CEDNIK-like features, such as microcephaly and skin defects. Consistent with Snap29 role in membrane fusion during autophagy, we observe accumulation of the autophagy markers p62 and LC3, and formation of aberrant multilamellar organelles and mitochondria. Importantly, we find high levels of apoptotic cell death during early development that might play a yet uncharacterized role in CEDNIK pathogenesis. Mutant larvae also display mouth opening problems, feeding impairment and swimming difficulties. These alterations correlate with defective trigeminal nerve formation and excess axonal branching. Since the paralog Snap25 is known to promote axonal branching, Snap29 might act in opposition with, or modulate Snap25 activity during neurodevelopment. Our vertebrate genetic model of CEDNIK extends the description in vivo of the multisystem defects due to loss of Snap29 and could provide the base to test compounds that might ameliorate traits of the disease.
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Affiliation(s)
- Valeria Mastrodonato
- IFOM, The FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
- University of Milan, Department of Biosciences, Via Celoria 26, 20133, Milan, Italy
| | - Galina Beznoussenko
- IFOM, The FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Alexandre Mironov
- IFOM, The FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Laura Ferrari
- IEO, European Institute of Oncology, via Adamello 16, 20139, Milan, Italy
| | - Gianluca Deflorian
- IFOM, The FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy.
| | - Thomas Vaccari
- University of Milan, Department of Biosciences, Via Celoria 26, 20133, Milan, Italy.
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19
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Wang X, Zhang X, Li F, Ji Q. MiR‐128‐3p accelerates cardiovascular calcification and insulin resistance through ISL1‐dependent Wnt pathway in type 2 diabetes mellitus rats. J Cell Physiol 2018; 234:4997-5010. [PMID: 30341898 DOI: 10.1002/jcp.27300] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 08/01/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Xin‐Yong Wang
- Department of Internal Medicine Linyi Jiaotong Hospital Linyi China
| | - Xian‐Zhao Zhang
- Department of Cardiology Linyi People's Hospital Linyi China
| | - Feng Li
- Clinical Laboratory The Third People's Hospital of Linyi Linyi China
| | - Qing‐Rong Ji
- Department of Cardiology Linyi People's Hospital Linyi China
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20
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Spatiotemporal expression of the cocaine- and amphetamine-regulated transcript-like (cart-like) gene during zebrafish embryogenesis. Gene Expr Patterns 2018; 30:1-6. [PMID: 30125742 DOI: 10.1016/j.gep.2018.08.002] [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: 04/11/2018] [Revised: 06/28/2018] [Accepted: 08/15/2018] [Indexed: 11/23/2022]
Abstract
The cocaine- and amphetamine-regulated transcript (CART) genes are involved in the neural regulation of energy homeostasis; however, their developmental expressions and functions are not fully understood in vertebrates. We have identified a novel zebrafish cart-like gene that encodes a protein of 105 amino acids possessing sequence similarity to zebrafish and mammalian CART proteins. RT-PCR analysis revealed that the cart-like transcripts were maternally supplied and gradually decreased during the cleavage, blastula and gastrula stages; then, transcripts subsequently reaccumulated at the segmentation, pharyngula and hatching stages. Based on a whole-mount in situ hybridization analysis using an antisense cart-like RNA probe, we found that the cart-like transcript was predominantly expressed in both the Rohon-Beard neurons and trigeminal ganglia, suggesting the involvement of the cart-like gene in zebrafish neural development.
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21
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Investigation of Islet2a function in zebrafish embryos: Mutants and morphants differ in morphologic phenotypes and gene expression. PLoS One 2018; 13:e0199233. [PMID: 29927984 PMCID: PMC6013100 DOI: 10.1371/journal.pone.0199233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 06/04/2018] [Indexed: 12/19/2022] Open
Abstract
Zebrafish primary motor neurons differ from each other with respect to morphology, muscle targets and electrophysiological properties. For example, CaP has 2-3-fold larger densities of both inward and outward currents than do other motor neurons. We tested whether the transcription factor Islet2a, uniquely expressed in CaP, but not other primary motor neurons, plays a role in specifying its stereotypic electrophysiological properties. We used both TALEN-based gene editing and antisense morpholino approaches to disrupt Islet2a function. Our electrophysiology results do not support a specific role for Islet2a in determining CaP’s unique electrical properties. However, we also found that the morphological phenotypes of CaP and a later-born motor neuron differed between islet2a mutants and morphants. Using microarrays, we tested whether the gene expression profiles of whole embryo morphants, mutants and controls also differed. Morphants had 174 and 201 genes that were differentially expressed compared to mutants and controls, respectively. Further, islet2a was identified as a differentially expressed gene. To examine how mutation of islet2a affected islet gene expression specifically in CaPs, we performed RNA in situ hybridization. We detected no obvious differences in expression of islet1, islet2a, or islet2b in CaPs of mutant versus sibling control embryos. However, immunolabeling studies revealed that an Islet protein persisted in CaPs of mutants, albeit at a reduced level compared to controls. While we cannot exclude requirement for some Islet protein, we conclude that differentiation of the CaP’s stereotypic large inward and outward currents does not have a specific requirement for Islet2a.
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22
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Allen JR, Bhattacharyya KD, Asante E, Almadi B, Schafer K, Davis J, Cox J, Voigt M, Viator JA, Chandrasekhar A. Role of branchiomotor neurons in controlling food intake of zebrafish larvae. J Neurogenet 2017; 31:128-137. [PMID: 28812416 PMCID: PMC5942883 DOI: 10.1080/01677063.2017.1358270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/18/2017] [Indexed: 10/19/2022]
Abstract
The physical act of eating or feeding involves the coordinated action of several organs like eyes and jaws, and associated neural networks. Moreover, the activity of the neural networks controlling jaw movements (branchiomotor circuits) is regulated by the visual, olfactory, gustatory and hypothalamic systems, which are largely well characterized at the physiological level. By contrast, the behavioral output of the branchiomotor circuits and the functional consequences of disruption of these circuits by abnormal neural development are poorly understood. To begin to address these questions, we sought to evaluate the feeding ability of zebrafish larvae, a direct output of the branchiomotor circuits, and developed a qualitative assay for measuring food intake in zebrafish larvae at 7 days post-fertilization. We validated the assay by examining the effects of ablating the branchiomotor neurons. Metronidazole-mediated ablation of nitroreductase-expressing branchiomotor neurons resulted in a predictable reduction in food intake without significantly affecting swimming ability, indicating that the assay is robust. Laser-mediated ablation of trigeminal motor neurons resulted in a significant decrease in food intake, indicating that the assay is sensitive. Importantly, in larvae of a genetic mutant with severe loss of branchiomotor neurons, food intake was abolished. These studies establish a foundation for dissecting the neural circuits driving a motor behavior essential for survival.
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Affiliation(s)
- James R. Allen
- Division of Biological Sciences, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Kiran D. Bhattacharyya
- Department of Biological Engineering, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Emilia Asante
- Division of Biological Sciences, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Badr Almadi
- Division of Biological Sciences, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Kyle Schafer
- Division of Biological Sciences, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Jeremy Davis
- Division of Biological Sciences, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Jane Cox
- Department of Pharmacology and Physiology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Mark Voigt
- Department of Pharmacology and Physiology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - John A. Viator
- Department of Biological Engineering, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
- Biomedical Engineering Program, Duquesne University, Pittsburgh, PA 15282, USA
| | - Anand Chandrasekhar
- Division of Biological Sciences, and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
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23
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McArthur KL, Fetcho JR. Key Features of Structural and Functional Organization of Zebrafish Facial Motor Neurons Are Resilient to Disruption of Neuronal Migration. Curr Biol 2017; 27:1746-1756.e5. [PMID: 28602649 DOI: 10.1016/j.cub.2017.05.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/15/2017] [Accepted: 05/10/2017] [Indexed: 11/30/2022]
Abstract
The location of neurons early in development can be critical for their ability to differentiate and receive normal synaptic inputs. Indeed, disruptions in neuronal positioning lead to a variety of neurological disorders. Neurons have, however, shifted their positions across phylogeny, suggesting that changes in location do not always spell functional disaster. To investigate the functional consequences of abnormal positioning, we leveraged previously reported genetic perturbations to disrupt normal neuronal migration-and thus positioning-in a population of cranial motor neurons, the facial branchiomotor neurons (FBMNs). We used a combination of topographical, morphological, physiological, and behavioral analyses to determine whether key functional features of FBMNs were still established in migration mutants, in spite of a dramatic rostrocaudal repositioning of these neurons in hindbrain. We discovered that FBMNs seem remarkably resilient to a disruption in positioning, suggesting that they may not rely heavily on rostrocaudal positioning to guide their functional development. Thus, the role of positioning may vary across the developing nervous system, with some populations-like facial motor neurons-exhibiting greater resilience to abnormal positioning that permits them to shift location as a part of evolutionary change.
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Affiliation(s)
- Kimberly L McArthur
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Joseph R Fetcho
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
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Bremer J, Skinner J, Granato M. A small molecule screen identifies in vivo modulators of peripheral nerve regeneration in zebrafish. PLoS One 2017; 12:e0178854. [PMID: 28575069 PMCID: PMC5456414 DOI: 10.1371/journal.pone.0178854] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/21/2017] [Indexed: 12/29/2022] Open
Abstract
Adult vertebrates have retained the ability to regenerate peripheral nerves after injury, although regeneration is frequently incomplete, often leading to functional impairments. Small molecule screens using whole organisms have high potential to identify biologically relevant targets, yet currently available assays for in vivo peripheral nerve regeneration are either very laborious and/or require complex technology. Here we take advantage of the optical transparency of larval zebrafish to develop a simple and fast pectoral fin removal assay that measures peripheral nerve regeneration in vivo. Twenty-four hours after fin amputation we observe robust and stereotyped nerve regrowth at the fin base. Similar to laser mediated nerve transection, nerve regrowth after fin amputation requires Schwann cells and FGF signaling, confirming that the fin amputation assay identifies pathways relevant for peripheral nerve regeneration. From a library of small molecules with known targets, we identified 21 compounds that impair peripheral nerve regeneration. Several of these compounds target known regulators of nerve regeneration, further validating the fin removal assay. Twelve of the identified compounds affect targets not previously known to control peripheral nerve regeneration. Using a laser-mediated nerve transection assay we tested ten of those compounds and confirmed six of these compounds to impair peripheral nerve regeneration: an EGFR inhibitor, a glucocorticoid, prostaglandin D2, a retinoic acid agonist, an inhibitor of calcium channels and a topoisomerase I inhibitor. Thus, we established a technically simple assay to rapidly identify valuable entry points into pathways critical for vertebrate peripheral nerve regeneration.
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Affiliation(s)
- Juliane Bremer
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Julianne Skinner
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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25
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Kabayiza KU, Masgutova G, Harris A, Rucchin V, Jacob B, Clotman F. The Onecut Transcription Factors Regulate Differentiation and Distribution of Dorsal Interneurons during Spinal Cord Development. Front Mol Neurosci 2017; 10:157. [PMID: 28603487 PMCID: PMC5445119 DOI: 10.3389/fnmol.2017.00157] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 05/08/2017] [Indexed: 01/09/2023] Open
Abstract
During embryonic development, the dorsal spinal cord generates numerous interneuron populations eventually involved in motor circuits or in sensory networks that integrate and transmit sensory inputs from the periphery. The molecular mechanisms that regulate the specification of these multiple dorsal neuronal populations have been extensively characterized. In contrast, the factors that contribute to their diversification into smaller specialized subsets and those that control the specific distribution of each population in the developing spinal cord remain unknown. Here, we demonstrate that the Onecut transcription factors, namely Hepatocyte Nuclear Factor-6 (HNF-6) (or OC-1), OC-2 and OC-3, regulate the diversification and the distribution of spinal dorsal interneuron (dINs). Onecut proteins are dynamically and differentially distributed in spinal dINs during differentiation and migration. Analyzes of mutant embryos devoid of Onecut factors in the developing spinal cord evidenced a requirement in Onecut proteins for proper production of a specific subset of dI5 interneurons. In addition, the distribution of dI3, dI5 and dI6 interneuron populations was altered. Hence, Onecut transcription factors control genetic programs that contribute to the regulation of spinal dIN diversification and distribution during embryonic development.
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Affiliation(s)
- Karolina U Kabayiza
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural DifferentiationBrussels, Belgium.,Biology Department, School of Science, College of Science and Technology, University of RwandaButare, Rwanda
| | - Gauhar Masgutova
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural DifferentiationBrussels, Belgium
| | - Audrey Harris
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural DifferentiationBrussels, Belgium
| | - Vincent Rucchin
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural DifferentiationBrussels, Belgium
| | - Benvenuto Jacob
- Université catholique de Louvain, Institute of Neuroscience, System and Cognition DivisionBrussels, Belgium
| | - Frédéric Clotman
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural DifferentiationBrussels, Belgium
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26
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Ermakova YG, Lanin AA, Fedotov IV, Roshchin M, Kelmanson IV, Kulik D, Bogdanova YA, Shokhina AG, Bilan DS, Staroverov DB, Balaban PM, Fedotov AB, Sidorov-Biryukov DA, Nikitin ES, Zheltikov AM, Belousov VV. Thermogenetic neurostimulation with single-cell resolution. Nat Commun 2017; 8:15362. [PMID: 28530239 PMCID: PMC5493594 DOI: 10.1038/ncomms15362] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 03/22/2017] [Indexed: 02/04/2023] Open
Abstract
Thermogenetics is a promising innovative neurostimulation technique, which enables robust activation of neurons using thermosensitive transient receptor potential (TRP) cation channels. Broader application of this approach in neuroscience is, however, hindered by a limited variety of suitable ion channels, and by low spatial and temporal resolution of neuronal activation when TRP channels are activated by ambient temperature variations or chemical agonists. Here, we demonstrate rapid, robust and reproducible repeated activation of snake TRPA1 channels heterologously expressed in non-neuronal cells, mouse neurons and zebrafish neurons in vivo by infrared (IR) laser radiation. A fibre-optic probe that integrates a nitrogen-vacancy (NV) diamond quantum sensor with optical and microwave waveguide delivery enables thermometry with single-cell resolution, allowing neurons to be activated by exceptionally mild heating, thus preventing the damaging effects of excessive heat. The neuronal responses to the activation by IR laser radiation are fully characterized using Ca2+ imaging and electrophysiology, providing, for the first time, a complete framework for a thermogenetic manipulation of individual neurons using IR light.
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Affiliation(s)
- Yulia G. Ermakova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
| | - Aleksandr A. Lanin
- Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
- Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 143025, Russia
- Kazan Quantum Center, A.N. Tupolev Kazan National Research Technical University, 420126 Kazan, Russia
| | - Ilya V. Fedotov
- Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia
- Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 143025, Russia
- Kazan Quantum Center, A.N. Tupolev Kazan National Research Technical University, 420126 Kazan, Russia
- Kurchatov Institute National Research Center, Moscow 123182, Russia
| | - Matvey Roshchin
- Institute of Higher Nervous Activity and Neurophysiology, Moscow 117485, Russia
| | - Ilya V. Kelmanson
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Dmitry Kulik
- Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia
- Present address: Zaporizhya State Engineering Academy, 69006 Zaporizhzhya, Ukraine
| | - Yulia A. Bogdanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Arina G. Shokhina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Dmitry S. Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
| | - Dmitry B. Staroverov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Pavel M. Balaban
- Institute of Higher Nervous Activity and Neurophysiology, Moscow 117485, Russia
| | - Andrei B. Fedotov
- Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
- Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 143025, Russia
- Kazan Quantum Center, A.N. Tupolev Kazan National Research Technical University, 420126 Kazan, Russia
| | - Dmitry A. Sidorov-Biryukov
- Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia
- Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 143025, Russia
- Kazan Quantum Center, A.N. Tupolev Kazan National Research Technical University, 420126 Kazan, Russia
| | - Evgeny S. Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Moscow 117485, Russia
| | - Aleksei M. Zheltikov
- Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
- Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 143025, Russia
- Kazan Quantum Center, A.N. Tupolev Kazan National Research Technical University, 420126 Kazan, Russia
- Kurchatov Institute National Research Center, Moscow 123182, Russia
| | - Vsevolod V. Belousov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
- Institute for Cardiovascular Physiology, Georg August University Göttingen, D-37075 Göttingen, Germany
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27
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Zhang R, Knapp M, Kause F, Reutter H, Ludwig M. Role of the LF-SINE-Derived Distal ISL1 Enhancer in Patients with Classic Bladder Exstrophy. J Pediatr Genet 2017; 6:169-173. [PMID: 28794909 DOI: 10.1055/s-0037-1602387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 03/20/2017] [Indexed: 10/19/2022]
Abstract
A genome-wide association study and meta-analysis identified ISL1 as the first genome-wide significant susceptibility gene for classic bladder exstrophy (CBE). A short interspersed repetitive element (SINE), first detected in lobe-finned fishes (LF-SINE), was shown to drive Isl1 expression in embryonic mouse genital eminence. Hence, we assumed this enhancer a conclusive target for mutations associated with CBE formation and analyzed a cohort of 200 CBE patients. Although we identified two enhancer variants in five CBE patients, their clinical significance seems unlikely, implying that sequence variants in the ISL1 LF-SINE enhancer are not frequently associated with CBE.
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Affiliation(s)
- Rong Zhang
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Michael Knapp
- Institute of Medical Biometry, Informatics, and Epidemiology, University of Bonn, Bonn, Germany
| | - Franziska Kause
- Institute of Human Genetics, University of Bonn, Bonn, Germany
| | - Heiko Reutter
- Institute of Human Genetics, University of Bonn, Bonn, Germany.,Department of Neonatology and Pediatric Intensive Care, Children's Hospital, University of Bonn, Bonn, Germany
| | - Michael Ludwig
- Department of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
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28
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The Isl1-Lhx3 Complex Promotes Motor Neuron Specification by Activating Transcriptional Pathways that Enhance Its Own Expression and Formation. eNeuro 2017; 4:eN-NWR-0349-16. [PMID: 28451636 PMCID: PMC5394944 DOI: 10.1523/eneuro.0349-16.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 02/27/2017] [Accepted: 03/11/2017] [Indexed: 01/27/2023] Open
Abstract
Motor neuron (MN) progenitor cells rapidly induce high expression of the transcription factors Islet-1 (Isl1), LIM-homeobox 3 (Lhx3), and the transcriptional regulator LMO4, as they differentiate. While these factors are critical for MN specification, the mechanisms regulating their precise temporal and spatial expression patterns are not well characterized. Isl1 and Lhx3 form the Isl1-Lhx3 complex, which induces the transcription of genes critical for MN specification and maturation. Here, we report that Isl1, Lhx3, and Lmo4 are direct target genes of the Isl1-Lhx3 complex. Our results show that specific genomic loci associated with these genes recruit the Isl1-Lhx3 complex to activate the transcription of Isl1, Lhx3, and Lmo4 in embryonic MNs of chick and mouse. These findings support a model in which the Isl1-Lhx3 complex amplifies its own expression through a potent autoregulatory feedback loop and simultaneously enhances the transcription of Lmo4. LMO4 blocks the formation of the V2 interneuron-specifying Lhx3 complex. In developing MNs, this action inhibits the expression of V2 interneuron genes and increases the pool of unbound Lhx3 available to incorporate into the Isl1-Lhx3 complex. Identifying the pathways that regulate the expression of these key factors provides important insights into the genetic strategies utilized to promote MN differentiation and maturation.
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29
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Juárez-Morales JL, Martinez-De Luna RI, Zuber ME, Roberts A, Lewis KE. Zebrafish transgenic constructs label specific neurons in Xenopus laevis spinal cord and identify frog V0v spinal neurons. Dev Neurobiol 2017; 77:1007-1020. [PMID: 28188691 DOI: 10.1002/dneu.22490] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 01/26/2017] [Accepted: 02/08/2017] [Indexed: 12/19/2022]
Abstract
A correctly functioning spinal cord is crucial for locomotion and communication between body and brain but there are fundamental gaps in our knowledge of how spinal neuronal circuitry is established and functions. To understand the genetic program that regulates specification and functions of this circuitry, we need to connect neuronal molecular phenotypes with physiological analyses. Studies using Xenopus laevis tadpoles have increased our understanding of spinal cord neuronal physiology and function, particularly in locomotor circuitry. However, the X. laevis tetraploid genome and long generation time make it difficult to investigate how neurons are specified. The opacity of X. laevis embryos also makes it hard to connect functional classes of neurons and the genes that they express. We demonstrate here that Tol2 transgenic constructs using zebrafish enhancers that drive expression in specific zebrafish spinal neurons label equivalent neurons in X. laevis and that the incorporation of a Gal4:UAS amplification cassette enables cells to be observed in live X. laevis tadpoles. This technique should enable the molecular phenotypes, morphologies and physiologies of distinct X. laevis spinal neurons to be examined together in vivo. We have used an islet1 enhancer to label Rohon-Beard sensory neurons and evx enhancers to identify V0v neurons, for the first time, in X. laevis spinal cord. Our work demonstrates the homology of spinal cord circuitry in zebrafish and X. laevis, suggesting that future work could combine their relative strengths to elucidate a more complete picture of how vertebrate spinal cord neurons are specified, and function to generate behavior. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1007-1020, 2017.
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Affiliation(s)
- José L Juárez-Morales
- Department of Biology, Syracuse University, 107 College Place, Syracuse, New York, 13244.,Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, United Kingdom
| | - Reyna I Martinez-De Luna
- The Center for Vision Research, Department of Ophthalmology, SUNY Upstate Medical University, Institute for Human Performance, 505 Irving Ave. Syracuse, New York, 13210
| | - Michael E Zuber
- The Center for Vision Research, Department of Ophthalmology, SUNY Upstate Medical University, Institute for Human Performance, 505 Irving Ave. Syracuse, New York, 13210
| | - Alan Roberts
- School of Biological Sciences, Bristol University, 24 Tyndall Avenue, Bristol, BS8 1TQ, United Kingdom
| | - Katharine E Lewis
- Department of Biology, Syracuse University, 107 College Place, Syracuse, New York, 13244
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30
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Divergent Hox Coding and Evasion of Retinoid Signaling Specifies Motor Neurons Innervating Digit Muscles. Neuron 2017; 93:792-805.e4. [PMID: 28190640 DOI: 10.1016/j.neuron.2017.01.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/13/2016] [Accepted: 01/20/2017] [Indexed: 11/21/2022]
Abstract
The establishment of spinal motor neuron subclass diversity is achieved through developmental programs that are aligned with the organization of muscle targets in the limb. The evolutionary emergence of digits represents a specialized adaptation of limb morphology, yet it remains unclear how the specification of digit-innervating motor neuron subtypes parallels the elaboration of digits. We show that digit-innervating motor neurons can be defined by selective gene markers and distinguished from other LMC neurons by the expression of a variant Hox gene repertoire and by the failure to express a key enzyme involved in retinoic acid synthesis. This divergent developmental program is sufficient to induce the specification of digit-innervating motor neurons, emphasizing the specialized status of digit control in the evolution of skilled motor behaviors. Our findings suggest that the emergence of digits in the limb is matched by distinct mechanisms for specifying motor neurons that innervate digit muscles.
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31
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Tapia VS, Herrera‐Rojas M, Larrain J. JAK-STAT pathway activation in response to spinal cord injury in regenerative and non-regenerative stages of Xenopus laevis. REGENERATION (OXFORD, ENGLAND) 2017; 4:21-35. [PMID: 28316792 PMCID: PMC5350081 DOI: 10.1002/reg2.74] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 12/13/2022]
Abstract
Xenopus laevis tadpoles can regenerate the spinal cord after injury but this capability is lost during metamorphosis. Comparative studies between pre-metamorphic and metamorphic Xenopus stages can aid towards understanding the molecular mechanisms of spinal cord regeneration. Analysis of a previous transcriptome-wide study suggests that, in response to injury, the JAK-STAT pathway is differentially activated in regenerative and non-regenerative stages. We characterized the activation of the JAK-STAT pathway and found that regenerative tadpoles have an early and transient activation. In contrast, the non-regenerative stages have a delayed and sustained activation of the pathway. We found that STAT3 is activated in response to injury mainly in Sox2/3+ ependymal cells, motoneurons and sensory neurons. Finally, to study the role of temporal activation we generated a transgenic line to express a constitutively active version of STAT3. The sustained activation of the JAK-STAT pathway in regenerative tadpoles reduced the expression of pro-neurogenic genes normally upregulated in response to spinal cord injury, suggesting that activation of the JAK-STAT pathway modulates the fate of neural progenitors.
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Affiliation(s)
- Victor S. Tapia
- Center for Aging and RegenerationMillennium Nucleus in Regenerative BiologyFacultad de Ciencias BiologicasPontificia Universidad Catolica de ChileSantiagoChile
| | - Mauricio Herrera‐Rojas
- Center for Aging and RegenerationMillennium Nucleus in Regenerative BiologyFacultad de Ciencias BiologicasPontificia Universidad Catolica de ChileSantiagoChile
| | - Juan Larrain
- Center for Aging and RegenerationMillennium Nucleus in Regenerative BiologyFacultad de Ciencias BiologicasPontificia Universidad Catolica de ChileSantiagoChile
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Abstract
Myelination by oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system is essential for nervous system function and health. Despite its importance, we have a relatively poor understanding of the molecular and cellular mechanisms that regulate myelination in the living animal, particularly in the CNS. This is partly due to the fact that myelination commences around birth in mammals, by which time the CNS is complex and largely inaccessible, and thus very difficult to image live in its intact form. As a consequence, in recent years much effort has been invested in the use of smaller, simpler, transparent model organisms to investigate mechanisms of myelination in vivo. Although the majority of such studies have employed zebrafish, the Xenopus tadpole also represents an important complementary system with advantages for investigating myelin biology in vivo. Here we review how the natural features of zebrafish embryos and larvae and Xenopus tadpoles make them ideal systems for experimentally interrogating myelination by live imaging. We outline common transgenic technologies used to generate zebrafish and Xenopus that express fluorescent reporters, which can be used to image myelination. We also provide an extensive overview of the imaging modalities most commonly employed to date to image the nervous system in these transparent systems, and also emerging technologies that we anticipate will become widely used in studies of zebrafish and Xenopus myelination in the near future.
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Affiliation(s)
- Jenea M Bin
- Centre for Neuroregeneration, MS Society Centre for Translational Research, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - David A Lyons
- Centre for Neuroregeneration, MS Society Centre for Translational Research, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
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33
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Cadherin-2 Is Required Cell Autonomously for Collective Migration of Facial Branchiomotor Neurons. PLoS One 2016; 11:e0164433. [PMID: 27716840 PMCID: PMC5055392 DOI: 10.1371/journal.pone.0164433] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/26/2016] [Indexed: 11/19/2022] Open
Abstract
Collective migration depends on cell-cell interactions between neighbors that contribute to their overall directionality, yet the mechanisms that control the coordinated migration of neurons remains to be elucidated. During hindbrain development, facial branchiomotor neurons (FBMNs) undergo a stereotypic tangential caudal migration from their place of birth in rhombomere (r)4 to their final location in r6/7. FBMNs engage in collective cell migration that depends on neuron-to-neuron interactions to facilitate caudal directionality. Here, we demonstrate that Cadherin-2-mediated neuron-to-neuron adhesion is necessary for directional and collective migration of FBMNs. We generated stable transgenic zebrafish expressing dominant-negative Cadherin-2 (Cdh2ΔEC) driven by the islet1 promoter. Cell-autonomous inactivation of Cadherin-2 function led to non-directional migration of FBMNs and a defect in caudal tangential migration. Additionally, mosaic analysis revealed that Cdh2ΔEC-expressing FBMNs are not influenced to migrate caudally by neighboring wild-type FBMNs due to a defect in collective cell migration. Taken together, our data suggest that Cadherin-2 plays an essential cell-autonomous role in mediating the collective migration of FBMNs.
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Live Imaging of Calcium Dynamics during Axon Degeneration Reveals Two Functionally Distinct Phases of Calcium Influx. J Neurosci 2016; 35:15026-38. [PMID: 26558774 DOI: 10.1523/jneurosci.2484-15.2015] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
UNLABELLED Calcium is a key regulator of axon degeneration caused by trauma and disease, but its specific spatial and temporal dynamics in injured axons remain unclear. To clarify the function of calcium in axon degeneration, we observed calcium dynamics in single injured neurons in live zebrafish larvae and tested the temporal requirement for calcium in zebrafish neurons and cultured mouse DRG neurons. Using laser axotomy to induce Wallerian degeneration (WD) in zebrafish peripheral sensory axons, we monitored calcium dynamics from injury to fragmentation, revealing two stereotyped phases of axonal calcium influx. First, axotomy triggered a transient local calcium wave originating at the injury site. This initial calcium wave only disrupted mitochondria near the injury site and was not altered by expression of the protective WD slow (WldS) protein. Inducing multiple waves with additional axotomies did not change the kinetics of degeneration. In contrast, a second phase of calcium influx occurring minutes before fragmentation spread as a wave throughout the axon, entered mitochondria, and was abolished by WldS expression. In live zebrafish, chelating calcium after the first wave, but before the second wave, delayed the progress of fragmentation. In cultured DRG neurons, chelating calcium early in the process of WD did not alter degeneration, but chelating calcium late in WD delayed fragmentation. We propose that a terminal calcium wave is a key instructive component of the axon degeneration program. SIGNIFICANCE STATEMENT Axon degeneration resulting from trauma or neurodegenerative disease can cause devastating deficits in neural function. Understanding the molecular and cellular events that execute axon degeneration is essential for developing treatments to address these conditions. Calcium is known to contribute to axon degeneration, but its temporal requirements in this process have been unclear. Live calcium imaging in severed zebrafish neurons and temporally controlled pharmacological treatments in both zebrafish and cultured mouse sensory neurons revealed that axonal calcium influx late in the degeneration process regulates axon fragmentation. These findings suggest that temporal considerations will be crucial for developing treatments for diseases associated with axon degeneration.
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35
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Catela C, Shin MM, Lee DH, Liu JP, Dasen JS. Hox Proteins Coordinate Motor Neuron Differentiation and Connectivity Programs through Ret/Gfrα Genes. Cell Rep 2016; 14:1901-15. [PMID: 26904955 DOI: 10.1016/j.celrep.2016.01.067] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/07/2015] [Accepted: 01/21/2016] [Indexed: 11/25/2022] Open
Abstract
The accuracy of neural circuit assembly relies on the precise spatial and temporal control of synaptic specificity determinants during development. Hox transcription factors govern key aspects of motor neuron (MN) differentiation; however, the terminal effectors of their actions are largely unknown. We show that Hox/Hox cofactor interactions coordinate MN subtype diversification and connectivity through Ret/Gfrα receptor genes. Hox and Meis proteins determine the levels of Ret in MNs and define the intrasegmental profiles of Gfrα1 and Gfrα3 expression. Loss of Ret or Gfrα3 leads to MN specification and innervation defects similar to those observed in Hox mutants, while expression of Ret and Gfrα1 can bypass the requirement for Hox genes during MN pool differentiation. These studies indicate that Hox proteins contribute to neuronal fate and muscle connectivity through controlling the levels and pattern of cell surface receptor expression, consequently gating the ability of MNs to respond to limb-derived instructive cues.
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Affiliation(s)
- Catarina Catela
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Maggie M Shin
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - David H Lee
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Jeh-Ping Liu
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Jeremy S Dasen
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA.
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Isaacman-Beck J, Schneider V, Franzini-Armstrong C, Granato M. The lh3 Glycosyltransferase Directs Target-Selective Peripheral Nerve Regeneration. Neuron 2015; 88:691-703. [PMID: 26549330 PMCID: PMC4655140 DOI: 10.1016/j.neuron.2015.10.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 08/16/2015] [Accepted: 09/28/2015] [Indexed: 12/26/2022]
Abstract
Functional PNS regeneration requires injured axons to return to their original synaptic targets, yet the mechanisms underlying target-selective regeneration have remained elusive. Using live-cell imaging in zebrafish we find that regenerating motor axons exhibit a strong preference for their original muscle territory and that axons probe both correct and incorrect trajectories extensively before selecting their original path. We show that this process requires the glycosyltransferase lh3 and that post-injury expression of lh3 in Schwann cells is sufficient to restore target-selective regeneration. Moreover, we demonstrate that Schwann cells neighboring the transection site express the lh3 substrate collagen4a5 and that during regeneration collagen4a5 destabilizes axons probing inappropriate trajectories to ensure target-selective regeneration, possibly through the axonal repellant slit1a. Our results demonstrate that selective ECM components match subpopulations of regenerating axons with their original targets and reveal a previously unappreciated mechanism that conveys synaptic target selection to regenerating axons in vivo. VIDEO ABSTRACT.
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Affiliation(s)
- Jesse Isaacman-Beck
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6058, USA
| | - Valerie Schneider
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6058, USA
| | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6058, USA
| | - Michael Granato
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6058, USA.
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Kim N, Park C, Jeong Y, Song MR. Functional Diversification of Motor Neuron-specific Isl1 Enhancers during Evolution. PLoS Genet 2015; 11:e1005560. [PMID: 26447474 PMCID: PMC4598079 DOI: 10.1371/journal.pgen.1005560] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 09/09/2015] [Indexed: 11/19/2022] Open
Abstract
Functional diversification of motor neurons has occurred in order to selectively control the movements of different body parts including head, trunk and limbs. Here we report that transcription of Isl1, a major gene necessary for motor neuron identity, is controlled by two enhancers, CREST1 (E1) and CREST2 (E2) that allow selective gene expression of Isl1 in motor neurons. Introduction of GFP reporters into the chick neural tube revealed that E1 is active in hindbrain motor neurons and spinal cord motor neurons, whereas E2 is active in the lateral motor column (LMC) of the spinal cord, which controls the limb muscles. Genome-wide ChIP-Seq analysis combined with reporter assays showed that Phox2 and the Isl1-Lhx3 complex bind to E1 and drive hindbrain and spinal cord-specific expression of Isl1, respectively. Interestingly, Lhx3 alone was sufficient to activate E1, and this may contribute to the initiation of Isl1 expression when progenitors have just developed into motor neurons. E2 was induced by onecut 1 (OC-1) factor that permits Isl1 expression in LMCm neurons. Interestingly, the core region of E1 has been conserved in evolution, even in the lamprey, a jawless vertebrate with primitive motor neurons. All E1 sequences from lamprey to mouse responded equally well to Phox2a and the Isl1-Lhx3 complex. Conversely, E2, the enhancer for limb-innervating motor neurons, was only found in tetrapod animals. This suggests that evolutionarily-conserved enhancers permit the diversification of motor neurons. During evolution, motor neurons became specialized to control movements of different body parts including head, trunk and limbs. Here we report that two enhancers of Isl1, E1 and E2, are active together with transcription factors in motor neurons. Surprisingly, E1 and its response to transcription factors has been conserved in evolution from the lamprey to man, whereas E2 is only found in animals with limbs. Our study provides an evolutionary example of how functional diversification of motor neurons is achieved by a dynamic interplay between enhancers and transcription factors.
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Affiliation(s)
- Namhee Kim
- School of Life Sciences, Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, Republic of Korea
| | - Chungoo Park
- School of Biological Sciences and Technology, Chonnam National University, Yongbong-ro, Buk-gu, Gwangju, Republic of Korea
| | - Yongsu Jeong
- Department of Genetic Engineering, College of Life Sciences and Graduate School of Biotechnology, Kyung Hee University, Yongin-si, Republic of Korea
| | - Mi-Ryoung Song
- School of Life Sciences, Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Oryong-dong, Buk-gu, Gwangju, Republic of Korea
- * E-mail:
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Bui TV, Stifani N, Panek I, Farah C. Genetically identified spinal interneurons integrating tactile afferents for motor control. J Neurophysiol 2015; 114:3050-63. [PMID: 26445867 DOI: 10.1152/jn.00522.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/28/2015] [Indexed: 11/22/2022] Open
Abstract
Our movements are shaped by our perception of the world as communicated by our senses. Perception of sensory information has been largely attributed to cortical activity. However, a prior level of sensory processing occurs in the spinal cord. Indeed, sensory inputs directly project to many spinal circuits, some of which communicate with motor circuits within the spinal cord. Therefore, the processing of sensory information for the purpose of ensuring proper movements is distributed between spinal and supraspinal circuits. The mechanisms underlying the integration of sensory information for motor control at the level of the spinal cord have yet to be fully described. Recent research has led to the characterization of spinal neuron populations that share common molecular identities. Identification of molecular markers that define specific populations of spinal neurons is a prerequisite to the application of genetic techniques devised to both delineate the function of these spinal neurons and their connectivity. This strategy has been used in the study of spinal neurons that receive tactile inputs from sensory neurons innervating the skin. As a result, the circuits that include these spinal neurons have been revealed to play important roles in specific aspects of motor function. We describe these genetically identified spinal neurons that integrate tactile information and the contribution of these studies to our understanding of how tactile information shapes motor output. Furthermore, we describe future opportunities that these circuits present for shedding light on the neural mechanisms of tactile processing.
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Affiliation(s)
- Tuan V Bui
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada; Center for Neural Dynamics, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Nicolas Stifani
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Izabela Panek
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carl Farah
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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Stil A, Drapeau P. Neuronal labeling patterns in the spinal cord of adult transgenic Zebrafish. Dev Neurobiol 2015; 76:642-60. [PMID: 26408263 DOI: 10.1002/dneu.22350] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 09/13/2015] [Accepted: 09/14/2015] [Indexed: 01/20/2023]
Abstract
We describe neuronal patterns in the spinal cord of adult zebrafish. We studied the distribution of cells and processes in the three spinal regions reported in the literature: the 8th vertebra used as a transection injury site, the 15th vertebra mainly used for motor cell recordings and also for crush injury, and the 24th vertebra used to record motor nerve activity. We used well-known transgenic lines in which expression of green fluorescent protein (GFP) is driven by promoters to hb9 and isl1 in motoneurons, alx/chx10 and evx1 interneurons, ngn1 in sensory neurons and olig2 in oligodendrocytes, as well as antibodies for neurons (HuC/D, NF and SV2) and glia (GFAP). In isl1:GFP fish, GFP-positive processes are retained in the upper part of ventral horns and two subsets of cell bodies are observed. The pattern of the transgene in hb9:GFP adults is more diffuse and fibers are present broadly through the adult spinal cord. In alx/chx10 and evx1 lines we respectively observed two and three different GFP-positive populations. Finally, the ngn1:GFP transgene identifies dorsal root ganglion and some cells in dorsal horns. Interestingly some GFP positive fibers in ngn1:GFP fish are located around Mauthner axons and their density seems to be related to a rostrocaudal gradient. Many other cell types have been described in embryos and need to be studied in adults. Our findings provide a reference for further studies on spinal cytoarchitecture. Combined with physiological, histological and pathological/traumatic approaches, these studies will help clarify the operation of spinal locomotor circuits of adult zebrafish.
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Affiliation(s)
- Aurélie Stil
- Hospital Research Centre (CRCHUM) and Department of Neurosciences, Université de Montréal, Montréal, Quebec, Canada, H2X 0A9
| | - Pierre Drapeau
- Hospital Research Centre (CRCHUM) and Department of Neurosciences, Université de Montréal, Montréal, Quebec, Canada, H2X 0A9
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Sato S, Yajima H, Furuta Y, Ikeda K, Kawakami K. Activation of Six1 Expression in Vertebrate Sensory Neurons. PLoS One 2015; 10:e0136666. [PMID: 26313368 PMCID: PMC4551851 DOI: 10.1371/journal.pone.0136666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/05/2015] [Indexed: 12/31/2022] Open
Abstract
SIX1 homeodomain protein is one of the essential key regulators of sensory organ development. Six1-deficient mice lack the olfactory epithelium, vomeronasal organs, cochlea, vestibule and vestibuloacoustic ganglion, and also show poor neural differentiation in the distal part of the cranial ganglia. Simultaneous loss of both Six1 and Six4 leads to additional abnormalities such as small trigeminal ganglion and abnormal dorsal root ganglia (DRG). The aim of this study was to understand the molecular mechanism that controls Six1 expression in sensory organs, particularly in the trigeminal ganglion and DRG. To this end, we focused on the sensory ganglia-specific Six1 enhancer (Six1-8) conserved between chick and mouse. In vivo reporter assays using both animals identified an important core region comprising binding consensus sequences for several transcription factors including nuclear hormone receptors, TCF/LEF, SMAD, POU homeodomain and basic-helix-loop-helix proteins. The results provided information on upstream factors and signals potentially relevant to Six1 regulation in sensory neurons. We also report the establishment of a new transgenic mouse line (mSix1-8-NLSCre) that expresses Cre recombinase under the control of mouse Six1-8. Cre-mediated recombination was detected specifically in ISL1/2-positive sensory neurons of Six1-positive cranial sensory ganglia and DRG. The unique features of the mSix1-8-NLSCre line are the absence of Cre-mediated recombination in SOX10-positive glial cells and central nervous system and ability to induce recombination in a subset of neurons derived from the olfactory placode/epithelium. This mouse model can be potentially used to advance research on sensory development.
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Affiliation(s)
- Shigeru Sato
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
- * E-mail:
| | - Hiroshi Yajima
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - Yasuhide Furuta
- Animal Resource Development Unit and Genetic Engineering Team, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies (CLST), Kobe, Hyogo, Japan
| | - Keiko Ikeda
- Division of Biology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Kiyoshi Kawakami
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
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Carmean V, Yonkers MA, Tellez MB, Willer JR, Willer GB, Gregg RG, Geisler R, Neuhauss SC, Ribera AB. pigk Mutation underlies macho behavior and affects Rohon-Beard cell excitability. J Neurophysiol 2015; 114:1146-57. [PMID: 26133798 DOI: 10.1152/jn.00355.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/25/2015] [Indexed: 12/20/2022] Open
Abstract
The study of touch-evoked behavior allows investigation of both the cells and circuits that generate a response to tactile stimulation. We investigate a touch-insensitive zebrafish mutant, macho (maco), previously shown to have reduced sodium current amplitude and lack of action potential firing in sensory neurons. In the genomes of mutant but not wild-type embryos, we identify a mutation in the pigk gene. The encoded protein, PigK, functions in attachment of glycophosphatidylinositol anchors to precursor proteins. In wild-type embryos, pigk mRNA is present at times when mutant embryos display behavioral phenotypes. Consistent with the predicted loss of function induced by the mutation, knock-down of PigK phenocopies maco touch insensitivity and leads to reduced sodium current (INa) amplitudes in sensory neurons. We further test whether the genetic defect in pigk underlies the maco phenotype by overexpressing wild-type pigk in mutant embryos. We find that ubiquitous expression of wild-type pigk rescues the touch response in maco mutants. In addition, for maco mutants, expression of wild-type pigk restricted to sensory neurons rescues sodium current amplitudes and action potential firing in sensory neurons. However, expression of wild-type pigk limited to sensory cells of mutant embryos does not allow rescue of the behavioral touch response. Our results demonstrate an essential role for pigk in generation of the touch response beyond that required for maintenance of proper INa density and action potential firing in sensory neurons.
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Affiliation(s)
- V Carmean
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - M A Yonkers
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - M B Tellez
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - J R Willer
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky; Zebrafish Mutant Mapping Facility, University of Louisville, Louisville, Kentucky; and
| | - G B Willer
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky; Zebrafish Mutant Mapping Facility, University of Louisville, Louisville, Kentucky; and
| | - R G Gregg
- Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, Kentucky; Zebrafish Mutant Mapping Facility, University of Louisville, Louisville, Kentucky; and
| | - R Geisler
- Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany
| | - S C Neuhauss
- Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany
| | - A B Ribera
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado;
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Abstract
Evolutionary modifications in nervous systems enabled organisms to adapt to their specific environments and underlie the remarkable diversity of behaviors expressed by animals. Resolving the pathways that shaped and modified neural circuits during evolution remains a significant challenge. Comparative studies have revealed a surprising conservation in the intrinsic signaling systems involved in early patterning of bilaterian nervous systems but also raise the question of how neural circuit compositions and architectures evolved within specific animal lineages. In this review, we discuss the mechanisms that contributed to the emergence and diversity of animal nervous systems, focusing on the circuits governing vertebrate locomotion.
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Affiliation(s)
- Heekyung Jung
- Howard Hughes Medical Institute (HHMI), NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA
| | - Jeremy S Dasen
- Howard Hughes Medical Institute (HHMI), NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA.
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43
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Love CE, Prince VE. Rest represses maturation within migrating facial branchiomotor neurons. Dev Biol 2015; 401:220-35. [PMID: 25769695 DOI: 10.1016/j.ydbio.2015.02.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/04/2015] [Accepted: 02/28/2015] [Indexed: 10/23/2022]
Abstract
The vertebrate brain arises from the complex organization of millions of neurons. Neurogenesis encompasses not only cell fate specification from neural stem cells, but also the terminal molecular and morphological maturation of neurons at correct positions within the brain. RE1-silencing transcription factor (Rest) is expressed in non-neural tissues and neuronal progenitors where it inhibits the terminal maturation of neurons by repressing hundreds of neuron-specific genes. Here we show that Rest repression of maturation is intimately linked with the migratory capability of zebrafish facial branchiomotor neurons (FBMNs), which undergo a characteristic tangential migration from hindbrain rhombomere (r) 4 to r6/r7 during development. We establish that FBMN migration is increasingly disrupted as Rest is depleted in zebrafish rest mutant embryos, such that around two-thirds of FBMNs fail to complete migration in mutants depleted of both maternal and zygotic Rest. Although Rest is broadly expressed, we show that de-repression or activation of Rest target genes only within FBMNs is sufficient to disrupt their migration. We demonstrate that this migration defect is due to precocious maturation of FBMNs, based on both morphological and molecular criteria. We further show that the Rest target gene and alternative splicing factor srrm4 is a key downstream regulator of maturation; Srrm4 knockdown partially restores the ability of FBMNs to migrate in rest mutants while preventing their precocious morphological maturation. Rest must localize to the nucleus to repress its targets, and its subcellular localization is highly regulated: we show that targeting Rest specifically to FBMN nuclei rescues FBMN migration in Rest-deficient embryos. We conclude that Rest functions in FBMN nuclei to inhibit maturation until the neurons complete their migration.
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Affiliation(s)
- Crystal E Love
- Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, IL 60615, USA
| | - Victoria E Prince
- Committee on Development, Regeneration and Stem Cell Biology, University of Chicago, Chicago, IL 60615, USA; Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.
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Theofilopoulos S, Griffiths WJ, Crick PJ, Yang S, Meljon A, Ogundare M, Kitambi SS, Lockhart A, Tuschl K, Clayton PT, Morris AA, Martinez A, Reddy MA, Martinuzzi A, Bassi MT, Honda A, Mizuochi T, Kimura A, Nittono H, De Michele G, Carbone R, Criscuolo C, Yau JL, Seckl JR, Schüle R, Schöls L, Sailer AW, Kuhle J, Fraidakis MJ, Gustafsson JÅ, Steffensen KR, Björkhem I, Ernfors P, Sjövall J, Arenas E, Wang Y. Cholestenoic acids regulate motor neuron survival via liver X receptors. J Clin Invest 2014; 124:4829-42. [PMID: 25271621 DOI: 10.1172/jci68506] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/21/2014] [Indexed: 11/17/2022] Open
Abstract
Cholestenoic acids are formed as intermediates in metabolism of cholesterol to bile acids, and the biosynthetic enzymes that generate cholestenoic acids are expressed in the mammalian CNS. Here, we evaluated the cholestenoic acid profile of mammalian cerebrospinal fluid (CSF) and determined that specific cholestenoic acids activate the liver X receptors (LXRs), enhance islet-1 expression in zebrafish, and increase the number of oculomotor neurons in the developing mouse in vitro and in vivo. While 3β,7α-dihydroxycholest-5-en-26-oic acid (3β,7α-diHCA) promoted motor neuron survival in an LXR-dependent manner, 3β-hydroxy-7-oxocholest-5-en-26-oic acid (3βH,7O-CA) promoted maturation of precursors into islet-1+ cells. Unlike 3β,7α-diHCA and 3βH,7O-CA, 3β-hydroxycholest-5-en-26-oic acid (3β-HCA) caused motor neuron cell loss in mice. Mutations in CYP7B1 or CYP27A1, which encode enzymes involved in cholestenoic acid metabolism, result in different neurological diseases, hereditary spastic paresis type 5 (SPG5) and cerebrotendinous xanthomatosis (CTX), respectively. SPG5 is characterized by spastic paresis, and similar symptoms may occur in CTX. Analysis of CSF and plasma from patients with SPG5 revealed an excess of the toxic LXR ligand, 3β-HCA, while patients with CTX and SPG5 exhibited low levels of the survival-promoting LXR ligand 3β,7α-diHCA. Moreover, 3β,7α-diHCA prevented the loss of motor neurons induced by 3β-HCA in the developing mouse midbrain in vivo.Our results indicate that specific cholestenoic acids selectively work on motor neurons, via LXR, to regulate the balance between survival and death.
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45
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Carlisle TC, Ribera AB. Connexin 35b expression in the spinal cord of Danio rerio embryos and larvae. J Comp Neurol 2014; 522:861-75. [PMID: 23939687 DOI: 10.1002/cne.23449] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/10/2013] [Accepted: 08/02/2013] [Indexed: 11/11/2022]
Abstract
Electrical synapses are expressed prominently in the developing and mature nervous systems. Unlike chemical synapses, little is known about the developmental role of electrical synapses, reflecting the limitations imposed by the lack of selective pharmacological blockers. At a molecular level, the building blocks of electrical synapses are connexin proteins. In this study, we report the expression pattern for neuronally expressed connexin 35b (cx35b), the zebrafish orthologue of mammalian connexin (Cx) 36. We find that cx35b is expressed at the time of neural induction, indicating a possible early role in neural progenitor cells. Additionally, cx35b localizes to the ventral spinal cord during embryonic and early larval stages. We detect cx35b mRNA in secondary motor neurons (SMNs) and interneurons. We identified the premotor circumferential descending (CiD) interneuron as one interneuron subtype expressing cx35b. In addition, cx35b is present in other ventral interneurons of unknown subtype(s). This early expression of cx35b in SMNs and CiDs suggests a possible role in motor network function during embryonic and larval stages.
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Affiliation(s)
- Tara C Carlisle
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045; Colorado Clinical and Translational Sciences Institute, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045; Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045
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Huang HS, Redmond TM, Kubish GM, Gupta S, Thompson RC, Turner DL, Uhler MD. Transcriptional regulatory events initiated by Ascl1 and Neurog2 during neuronal differentiation of P19 embryonic carcinoma cells. J Mol Neurosci 2014; 55:684-705. [PMID: 25189318 DOI: 10.1007/s12031-014-0408-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/20/2014] [Indexed: 11/25/2022]
Abstract
As members of the proneural basic-helix-loop-helix (bHLH) family of transcription factors, Ascl1 and Neurog2 direct the differentiation of specific populations of neurons at various times and locations within the developing nervous system. In order to characterize the mechanisms employed by these two bHLH factors, we generated stable, doxycycline-inducible lines of P19 embryonic carcinoma cells that express comparable levels of Ascl1 and Neurog2. Upon induction, both Ascl1 and Neurog2 directed morphological and immunocytochemical changes consistent with initiation of neuronal differentiation. Comparison of Ascl1- and Neurog2-regulated genes by microarray analyses showed both shared and distinct transcriptional changes for each bHLH protein. In both Ascl1- and Neurog2-differentiating cells, repression of Oct4 mRNA levels was accompanied by increased Oct4 promoter methylation. However, DNA demethylation was not detected for genes induced by either bHLH protein. Neurog2-induced genes included glutamatergic marker genes while Ascl1-induced genes included GABAergic marker genes. The Neurog2-specific induction of a gene encoding a protein phosphatase inhibitor, Ppp1r14a, was dependent on distinct, canonical E-box sequences within the Ppp1r14a promoter and the nucleotide sequences within these E-boxes were partially responsible for Neurog2-specific regulation. Our results illustrate multiple novel mechanisms by which Ascl1 and Neurog2 regulate gene repression during neuronal differentiation in P19 cells.
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Affiliation(s)
- Holly S Huang
- Molecular and Behavioral Neuroscience Institute, University of Michigan, 109 Zina Pitcher Pl, Ann Arbor, MI, 48109-2200, USA
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Moreno RL, Ribera AB. Spinal neurons require Islet1 for subtype-specific differentiation of electrical excitability. Neural Dev 2014; 9:19. [PMID: 25149090 PMCID: PMC4153448 DOI: 10.1186/1749-8104-9-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 07/16/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the spinal cord, stereotypic patterns of transcription factor expression uniquely identify neuronal subtypes. These transcription factors function combinatorially to regulate gene expression. Consequently, a single transcription factor may regulate divergent development programs by participation in different combinatorial codes. One such factor, the LIM-homeodomain transcription factor Islet1, is expressed in the vertebrate spinal cord. In mouse, chick and zebrafish, motor and sensory neurons require Islet1 for specification of biochemical and morphological signatures. Little is known, however, about the role that Islet1 might play for development of electrical membrane properties in vertebrates. Here we test for a role of Islet1 in differentiation of excitable membrane properties of zebrafish spinal neurons. RESULTS We focus our studies on the role of Islet1 in two populations of early born zebrafish spinal neurons: ventral caudal primary motor neurons (CaPs) and dorsal sensory Rohon-Beard cells (RBs). We take advantage of transgenic lines that express green fluorescent protein (GFP) to identify CaPs, RBs and several classes of interneurons for electrophysiological study. Upon knock-down of Islet1, cells occupying CaP-like and RB-like positions continue to express GFP. With respect to voltage-dependent currents, CaP-like and RB-like neurons have novel repertoires that distinguish them from control CaPs and RBs, and, in some respects, resemble those of neighboring interneurons. The action potentials fired by CaP-like and RB-like neurons also have significantly different properties compared to those elicited from control CaPs and RBs. CONCLUSIONS Overall, our findings suggest that, for both ventral motor and dorsal sensory neurons, Islet1 directs differentiation programs that ultimately specify electrical membrane as well as morphological properties that act together to sculpt neuron identity.
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Affiliation(s)
- Rosa L Moreno
- Department of Physiology, University of Colorado Anschutz Medical Campus, RC-1 North, 7403A, Mailstop 8307, 12800 E 19th Ave,, 80045 Aurora, CO, USA.
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48
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O'Donnell KC, Lulla A, Stahl MC, Wheat ND, Bronstein JM, Sagasti A. Axon degeneration and PGC-1α-mediated protection in a zebrafish model of α-synuclein toxicity. Dis Model Mech 2014; 7:571-82. [PMID: 24626988 PMCID: PMC4007408 DOI: 10.1242/dmm.013185] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
α-synuclein (aSyn) expression is implicated in neurodegenerative processes, including Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). In animal models of these diseases, axon pathology often precedes cell death, raising the question of whether aSyn has compartment-specific toxic effects that could require early and/or independent therapeutic intervention. The relevance of axonal pathology to degeneration can only be addressed through longitudinal, in vivo monitoring of different neuronal compartments. With current imaging methods, dopaminergic neurons do not readily lend themselves to such a task in any vertebrate system. We therefore expressed human wild-type aSyn in zebrafish peripheral sensory neurons, which project elaborate superficial axons that can be continuously imaged in vivo. Axonal outgrowth was normal in these neurons but, by 2 days post-fertilization (dpf), many aSyn-expressing axons became dystrophic, with focal varicosities or diffuse beading. Approximately 20% of aSyn-expressing cells died by 3 dpf. Time-lapse imaging revealed that focal axonal swelling, but not overt fragmentation, usually preceded cell death. Co-expressing aSyn with a mitochondrial reporter revealed deficits in mitochondrial transport and morphology even when axons appeared overtly normal. The axon-protective protein Wallerian degeneration slow (WldS) delayed axon degeneration but not cell death caused by aSyn. By contrast, the transcriptional coactivator PGC-1α, which has roles in the regulation of mitochondrial biogenesis and reactive-oxygen-species detoxification, abrogated aSyn toxicity in both the axon and the cell body. The rapid onset of axonal pathology in this system, and the relatively moderate degree of cell death, provide a new model for the study of aSyn toxicity and protection. Moreover, the accessibility of peripheral sensory axons will allow effects of aSyn to be studied in different neuronal compartments and might have utility in screening for novel disease-modifying compounds.
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Affiliation(s)
- Kelley C O'Donnell
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
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Francius C, Clotman F. Generating spinal motor neuron diversity: a long quest for neuronal identity. Cell Mol Life Sci 2014; 71:813-29. [PMID: 23765105 PMCID: PMC11113339 DOI: 10.1007/s00018-013-1398-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/30/2013] [Accepted: 05/31/2013] [Indexed: 03/26/2023]
Abstract
Understanding how thousands of different neuronal types are generated in the CNS constitutes a major challenge for developmental neurobiologists and is a prerequisite before considering cell or gene therapies of nervous lesions or pathologies. During embryonic development, spinal motor neurons (MNs) segregate into distinct subpopulations that display specific characteristics and properties including molecular identity, migration pattern, allocation to specific motor columns, and innervation of defined target. Because of the facility to correlate these different characteristics, the diversification of spinal MNs has become the model of choice for studying the molecular and cellular mechanisms underlying the generation of multiple neuronal populations in the developing CNS. Therefore, how spinal motor neuron subpopulations are produced during development has been extensively studied during the last two decades. In this review article, we will provide a comprehensive overview of the genetic and molecular mechanisms that contribute to the diversification of spinal MNs.
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Affiliation(s)
- Cédric Francius
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, 55 Avenue Hippocrate, Box (B1.55.11), 1200 Brussels, Belgium
| | - Frédéric Clotman
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, 55 Avenue Hippocrate, Box (B1.55.11), 1200 Brussels, Belgium
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Aoki M, Segawa H, Naito M, Okamoto H. Identification of possible downstream genes required for the extension of peripheral axons in primary sensory neurons. Biochem Biophys Res Commun 2014; 445:357-62. [PMID: 24513284 DOI: 10.1016/j.bbrc.2014.01.193] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 01/31/2014] [Indexed: 10/25/2022]
Abstract
The LIM-homeodomain transcription factor Islet2a establishes neuronal identity in the developing nervous system. Our previous study showed that Islet2a function is crucial for extending peripheral axons of sensory neurons in zebrafish embryo. Overexpressing a dominant-negative form of Islet2a significantly reduced peripheral axon extension in zebrafish sensory neurons, implicating Islet2a in the gene regulation required for neurite formation or proper axon growth in developing sensory neurons. Based on this, we conducted systematic screening to isolate genes regulated by Islet2a and affecting the development of axon growth in embryonic zebrafish sensory neurons. The 26 genes selected included some encoding factors involved in neuronal differentiation, axon growth, cellular signaling, and structural integrity of neurons, as well as genes whose functions are not fully determined. We chose four representative candidates as possible Islet2a downstream functional targets (simplet, tppp, tusc5 and tmem59l) and analyzed their respective mRNA expressions in dominant-negative Islet2a-expressing embryos. They are not reported the involvement of axonal extension or their functions in neural cells. Finally, knockdown of these genes suggested their direct actual involvement in the extension of peripheral axons in sensory neurons.
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Affiliation(s)
- Makoto Aoki
- Laboratory for Developmental Gene Regulation, Brain Science Institute, Riken, Japan
| | - Hiroshi Segawa
- Laboratory for Developmental Gene Regulation, Brain Science Institute, Riken, Japan
| | - Mayumi Naito
- Laboratory for Developmental Gene Regulation, Brain Science Institute, Riken, Japan
| | - Hitoshi Okamoto
- Laboratory for Developmental Gene Regulation, Brain Science Institute, Riken, Japan.
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