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Hidalgo-Sánchez M, Andreu-Cervera A, Villa-Carballar S, Echevarria D. An Update on the Molecular Mechanism of the Vertebrate Isthmic Organizer Development in the Context of the Neuromeric Model. Front Neuroanat 2022; 16:826976. [PMID: 35401126 PMCID: PMC8987131 DOI: 10.3389/fnana.2022.826976] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
A crucial event during the development of the central nervous system (CNS) is the early subdivision of the neural tube along its anterior-to-posterior axis to form neuromeres, morphogenetic units separated by transversal constrictions and programed for particular genetic cascades. The narrower portions observed in the developing neural tube are responsible for relevant cellular and molecular processes, such as clonal restrictions, expression of specific regulatory genes, and differential fate specification, as well as inductive activities. In this developmental context, the gradual formation of the midbrain-hindbrain (MH) constriction has been an excellent model to study the specification of two major subdivisions of the CNS containing the mesencephalic and isthmo-cerebellar primordia. This MH boundary is coincident with the common Otx2-(midbrain)/Gbx2-(hindbrain) expressing border. The early interactions between these two pre-specified areas confer positional identities and induce the generation of specific diffusible morphogenes at this interface, in particular FGF8 and WNT1. These signaling pathways are responsible for the gradual histogenetic specifications and cellular identity acquisitions with in the MH domain. This review is focused on the cellular and molecular mechanisms involved in the specification of the midbrain/hindbrain territory and the formation of the isthmic organizer. Emphasis will be placed on the chick/quail chimeric experiments leading to the acquisition of the first fate mapping and experimental data to, in this way, better understand pioneering morphological studies and innovative gain/loss-of-function analysis.
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Affiliation(s)
- Matías Hidalgo-Sánchez
- Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain
- *Correspondence: Matías Hidalgo-Sánchez Diego Echevarria
| | - Abraham Andreu-Cervera
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
| | - Sergio Villa-Carballar
- Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain
| | - Diego Echevarria
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Alicante, Spain
- *Correspondence: Matías Hidalgo-Sánchez Diego Echevarria
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Alwin Prem Anand A, Alvarez-Bolado G, Wizenmann A. MiR-9 and the Midbrain-Hindbrain Boundary: A Showcase for the Limited Functional Conservation and Regulatory Complexity of MicroRNAs. Front Cell Dev Biol 2020; 8:586158. [PMID: 33330463 PMCID: PMC7719755 DOI: 10.3389/fcell.2020.586158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/23/2020] [Indexed: 11/15/2022] Open
Abstract
MicroRNAs regulate gene expression at post-transcriptional levels. Some of them appear to regulate brain development and are involved in neurodevelopmental disorders. This has led to the suggestion that the role of microRNAs in neuronal development and function may be more central than previously appreciated. Here, we review the data about miR-9 function to depict the subtlety, complexity, flexibility and limited functional conservation of this essential developmental regulatory system. On this basis we propose that species-specific actions of miR-9 could underlie to a large degree species differences in brain size, shape and function.
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Affiliation(s)
- A Alwin Prem Anand
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Tuebingen, Germany
| | | | - Andrea Wizenmann
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Tuebingen, Germany
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3
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Tambalo M, Mitter R, Wilkinson DG. A single cell transcriptome atlas of the developing zebrafish hindbrain. Development 2020; 147:dev184143. [PMID: 32094115 PMCID: PMC7097387 DOI: 10.1242/dev.184143] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 02/11/2020] [Indexed: 12/31/2022]
Abstract
Segmentation of the vertebrate hindbrain leads to the formation of rhombomeres, each with a distinct anteroposterior identity. Specialised boundary cells form at segment borders that act as a source or regulator of neuronal differentiation. In zebrafish, there is spatial patterning of neurogenesis in which non-neurogenic zones form at boundaries and segment centres, in part mediated by Fgf20 signalling. To further understand the control of neurogenesis, we have carried out single cell RNA sequencing of the zebrafish hindbrain at three different stages of patterning. Analyses of the data reveal known and novel markers of distinct hindbrain segments, of cell types along the dorsoventral axis, and of the transition of progenitors to neuronal differentiation. We find major shifts in the transcriptome of progenitors and of differentiating cells between the different stages analysed. Supervised clustering with markers of boundary cells and segment centres, together with RNA-seq analysis of Fgf-regulated genes, has revealed new candidate regulators of cell differentiation in the hindbrain. These data provide a valuable resource for functional investigations of the patterning of neurogenesis and the transition of progenitors to neuronal differentiation.
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Affiliation(s)
- Monica Tambalo
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Richard Mitter
- Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - David G Wilkinson
- Neural Development Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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Bloch S, Thomas M, Colin I, Galant S, Machado E, Affaticati P, Jenett A, Yamamoto K. Mesencephalic origin of the inferior lobe in zebrafish. BMC Biol 2019; 17:22. [PMID: 30849972 PMCID: PMC6407210 DOI: 10.1186/s12915-019-0631-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 01/22/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Although the overall brain organization is shared in vertebrates, there are significant differences within subregions among different groups, notably between Sarcopterygii (lobe-finned fish) and Actinopterygii (ray-finned fish). Recent comparative studies focusing on the ventricular morphology have revealed a large diversity of the hypothalamus. Here, we study the development of the inferior lobe (IL), a prominent structure forming a bump on the ventral surface of the teleost brain. Based on its position, IL has been thought to be part of the hypothalamus (therefore forebrain). RESULTS Taking advantage of genetic lineage-tracing techniques in zebrafish, we reveal that cells originating from her5-expressing progenitors in the midbrain-hindbrain boundary (MHB) participate in the formation of a large part of the IL. 3D visualization demonstrated how IL develops in relation to the ventricular system. We found that IL is constituted by two developmental components: the periventricular zone of hypothalamic origin and the external zone of mesencephalic origin. The mesencephalic external zone grows progressively until adulthood by adding new cells throughout development. CONCLUSION Our results disprove a homology between the IL and the mammalian lateral hypothalamus. We suggest that the IL is likely to be involved in multimodal sensory integration rather than feeding motivation. The teleost brain is not a simpler version of the mammalian brain, and our study highlights the evolutionary plasticity of the brain which gives rise to novel structures.
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Affiliation(s)
- Solal Bloch
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), CNRS UMR9197, Univ Paris Sud, Université Paris-Saclay, CNRS Bâtiment 5, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France
| | - Manon Thomas
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), CNRS UMR9197, Univ Paris Sud, Université Paris-Saclay, CNRS Bâtiment 5, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France
- Present address: Plateau de phénotypage TEFOR, LPGP-INRA UR1037, 35042, Rennes, France
| | - Ingrid Colin
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), CNRS UMR9197, Univ Paris Sud, Université Paris-Saclay, CNRS Bâtiment 5, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France
| | - Sonya Galant
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), CNRS UMR9197, Univ Paris Sud, Université Paris-Saclay, CNRS Bâtiment 5, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France
| | - Elodie Machado
- TEFOR Paris-Saclay, CNRS UMS2010, INRA UMS1451, Univ Paris Sud, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Pierre Affaticati
- TEFOR Paris-Saclay, CNRS UMS2010, INRA UMS1451, Univ Paris Sud, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Arnim Jenett
- TEFOR Paris-Saclay, CNRS UMS2010, INRA UMS1451, Univ Paris Sud, Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Kei Yamamoto
- Paris-Saclay Institute of Neuroscience (Neuro-PSI), CNRS UMR9197, Univ Paris Sud, Université Paris-Saclay, CNRS Bâtiment 5, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France.
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5
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Alwin Prem Anand A, Huber C, Asnet Mary J, Gallus N, Leucht C, Klafke R, Hirt B, Wizenmann A. Expression and function of microRNA-9 in the mid-hindbrain area of embryonic chick. BMC DEVELOPMENTAL BIOLOGY 2018; 18:3. [PMID: 29471810 PMCID: PMC5824543 DOI: 10.1186/s12861-017-0159-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 11/27/2017] [Indexed: 12/21/2022]
Abstract
Background MiR-9 is a small non-coding RNA that is highly conserved between species and primarily expressed in the central nervous system (CNS). It is known to influence proliferation and neuronal differentiation in the brain and spinal cord of different vertebrates. Different studies have pointed to regional and species-specific differences in the response of neural progenitors to miR-9. Methods In ovo and ex ovo electroporation was used to overexpress or reduce miR-9 followed by mRNA in situ hybridisation and immunofluorescent stainings to evaluate miR- expression and the effect of changed miR-9 expression. Results We have investigated the expression and function of miR-9 during early development of the mid-hindbrain region (MH) in chick. Our analysis reveals a closer relationship of chick miR-9 to mammalian miR-9 than to fish and a dynamic expression pattern in the chick neural tube. Early in development, miR-9 is diffusely expressed in the entire brain, bar the forebrain, and it becomes more restricted to specific areas of the CNS at later stages. MiR-9 overexpression at HH9–10 results in a reduction of FGF8 expression and premature neuronal differentiation in the mid-hindbrain boundary (MHB). Within the midbrain miR-9 does not cause premature neuronal differentiation it rather reduces proliferation in the midbrain. Conclusion Our findings indicate that miR-9 has regional specific effects in the developing mid-hindbrain region with a divergence of response of regional progenitors. Electronic supplementary material The online version of this article (10.1186/s12861-017-0159-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- A Alwin Prem Anand
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Oesterbergstrasse 3, D-72074, Tuebingen, Germany
| | - Carola Huber
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Oesterbergstrasse 3, D-72074, Tuebingen, Germany.,Robert-Bosch-Krankenhaus, Auerbachstraße 110, 70376, Stuttgart, Germany
| | - John Asnet Mary
- Department of Zoology, Fatima College, Madurai, Tamilnadu, 625018, India
| | - Nancy Gallus
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Oesterbergstrasse 3, D-72074, Tuebingen, Germany.,Department of Neurobiology, McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Christoph Leucht
- Institute of Developmental Genetics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
| | - Ruth Klafke
- Institute of Developmental Genetics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
| | - Bernhard Hirt
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Oesterbergstrasse 3, D-72074, Tuebingen, Germany
| | - Andrea Wizenmann
- Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Oesterbergstrasse 3, D-72074, Tuebingen, Germany.
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Mashanov VS, Zueva OR, García-Arrarás JE. Inhibition of cell proliferation does not slow down echinoderm neural regeneration. Front Zool 2017; 14:12. [PMID: 28250799 PMCID: PMC5324207 DOI: 10.1186/s12983-017-0196-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 02/07/2017] [Indexed: 01/14/2023] Open
Abstract
Background Regeneration of the damaged central nervous system is one of the most interesting post-embryonic developmental phenomena. Two distinct cellular events have been implicated in supplying regenerative neurogenesis with cellular material – generation of new cells through cell proliferation and recruitment of already existing cells through cell migration. The relative contribution and importance of these two mechanisms is often unknown. Methods Here, we use the regenerating radial nerve cord (RNC) of the echinoderm Holothuria glaberrima as a model of extensive post-traumatic neurogenesis in the deuterostome central nervous system. To uncouple the effects of cell proliferation from those of cell migration, we treated regenerating animals with aphidicolin, a specific inhibitor of S-phase DNA replication. To monitor the effect of aphidicolin on DNA synthesis, we used BrdU immunocytochemistry. The specific radial glial marker ERG1 was used to label the regenerating RNC. Cell migration was tracked with vital staining with the lipophilic dye DiI. Results Aphidicolin treatment resulted in a significant 2.1-fold decrease in cell proliferation. In spite of this, the regenerating RNC in the treated animals did not differ in histological architecture, size and cell number from its counterpart in the control vehicle-treated animals. DiI labeling showed extensive cell migration in the RNC. Some cells migrated from as far as 2 mm away from the injury plane to contribute to the neural outgrowth. Conclusions We suggest that inhibition of cell division in the regenerating RNC of H. glaberrima is compensated for by recruitment of cells, which migrate into the RNC outgrowth from deeper regions of the neuroepithelium. Neural regeneration in echinoderms is thus a highly regulative developmental phenomenon, in which the size of the cell pool can be controlled either by cell proliferation or cell migration, and the latter can neutralize perturbations in the former. Electronic supplementary material The online version of this article (doi:10.1186/s12983-017-0196-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vladimir S Mashanov
- University of North Florida, 1 UNF Drive, Jacksonville, 32224 FL USA.,University of Puerto Rico, Rio Piedras, PO Box 70377, San Juan, 00936-8377 PR USA
| | - Olga R Zueva
- University of North Florida, 1 UNF Drive, Jacksonville, 32224 FL USA.,University of Puerto Rico, Rio Piedras, PO Box 70377, San Juan, 00936-8377 PR USA
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Villasenor A, Stainier DYR. On the development of the hepatopancreatic ductal system. Semin Cell Dev Biol 2017; 66:69-80. [PMID: 28214561 DOI: 10.1016/j.semcdb.2017.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/03/2017] [Accepted: 02/13/2017] [Indexed: 12/13/2022]
Abstract
The hepatopancreatic ductal system is the collection of ducts that connect the liver and pancreas to the digestive tract. The formation of this system is necessary for the transport of exocrine secretions, for the correct assembly of the pancreatobiliary ductal system, and for the overall function of the digestive system. Studies on endoderm organ formation have significantly advanced our understanding of the molecular mechanisms that govern organ induction, organ specification and morphogenesis of the major foregut-derived organs. However, little is known about the mechanisms that control the development of the hepatopancreatic ductal system. Here, we provide a description of the different components of the system, summarize its development from the endoderm to a complex system of tubes, list the pathologies produced by anomalies in its development, as well as the molecules and signaling pathways that are known to be involved in its formation. Finally, we discuss its proposed potential as a multipotent cell reservoir and the unresolved questions in the field.
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Affiliation(s)
- Alethia Villasenor
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
| | - Didier Y R Stainier
- Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.
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8
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Galant S, Furlan G, Coolen M, Dirian L, Foucher I, Bally-Cuif L. Embryonic origin and lineage hierarchies of the neural progenitor subtypes building the zebrafish adult midbrain. Dev Biol 2016; 420:120-135. [PMID: 27693369 PMCID: PMC5156517 DOI: 10.1016/j.ydbio.2016.09.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 08/31/2016] [Accepted: 09/26/2016] [Indexed: 01/11/2023]
Abstract
Neurogenesis in the post-embryonic vertebrate brain varies in extent and efficiency between species and brain territories. Distinct neurogenesis modes may account for this diversity, and several neural progenitor subtypes, radial glial cells (RG) and neuroepithelial progenitors (NE), have been identified in the adult zebrafish brain. The neurogenic sequences issued from these progenitors, and their contribution to brain construction, remain incompletely understood. Here we use genetic tracing techniques based on conditional Cre recombination and Tet-On neuronal birthdating to unravel the neurogenic sequence operating from NE progenitors in the zebrafish post-embryonic optic tectum. We reveal that a subpopulation of her5-positive NE cells of the posterior midbrain layer stands at the top of a neurogenic hierarchy involving, in order, the amplification pool of the tectal proliferation zone (TPZ), followed by her4-positive RG cells with transient neurogenic activity. We further demonstrate that the adult her5-positive NE pool is issued in lineage from an identically located NE pool expressing the same gene in the embryonic neural tube. Finally, we show that these features are reminiscent of the neurogenic sequence and embryonic origin of the her9-positive progenitor NE pool involved in the construction of the lateral pallium at post-embryonic stages. Together, our results highlight the shared recruitment of an identical neurogenic strategy by two remote brain territories, where long-lasting NE pools serve both as a growth zone and as the life-long source of young neurogenic RG cells. Zebrafish post-embryonic tectal neurogenesis is driven by neuroepithelial progenitors. The neuroepithelial progenitor pool is long-lasting and expresses Her5 life long. Tectal radial glia originate from the her5-positive pool and are transiently neurogenic. The post-embryonic neurogenic sequences of the tectum and lateral pallium are similar.
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Affiliation(s)
- Sonya Galant
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France
| | - Giacomo Furlan
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France
| | - Marion Coolen
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France; Department of Developmental and Stem Cell Biology and CNRS UMR 3738, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France
| | - Lara Dirian
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France
| | - Isabelle Foucher
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France; Department of Developmental and Stem Cell Biology and CNRS UMR 3738, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France.
| | - Laure Bally-Cuif
- Paris-Saclay Institute for Neuroscience, CNRS UMR9197 - Université Paris-Sud, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Bldg 5, F-91198 Gif-sur-Yvette, France; Department of Developmental and Stem Cell Biology and CNRS UMR 3738, Institut Pasteur, 25 rue du Dr Roux, 75015 Paris, France.
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9
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Peretz Y, Eren N, Kohl A, Hen G, Yaniv K, Weisinger K, Cinnamon Y, Sela-Donenfeld D. A new role of hindbrain boundaries as pools of neural stem/progenitor cells regulated by Sox2. BMC Biol 2016; 14:57. [PMID: 27392568 PMCID: PMC4938926 DOI: 10.1186/s12915-016-0277-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/21/2016] [Indexed: 01/28/2023] Open
Abstract
Background Compartment boundaries are an essential developmental mechanism throughout evolution, designated to act as organizing centers and to regulate and localize differently fated cells. The hindbrain serves as a fascinating example for this phenomenon as its early development is devoted to the formation of repetitive rhombomeres and their well-defined boundaries in all vertebrates. Yet, the actual role of hindbrain boundaries remains unresolved, especially in amniotes. Results Here, we report that hindbrain boundaries in the chick embryo consist of a subset of cells expressing the key neural stem cell (NSC) gene Sox2. These cells co-express other neural progenitor markers such as Transitin (the avian Nestin), GFAP, Pax6 and chondroitin sulfate proteoglycan. The majority of the Sox2+ cells that reside within the boundary core are slow-dividing, whereas nearer to and within rhombomeres Sox2+ cells are largely proliferating. In vivo analyses and cell tracing experiments revealed the contribution of boundary Sox2+ cells to neurons in a ventricular-to-mantle manner within the boundaries, as well as their lateral contribution to proliferating Sox2+ cells in rhombomeres. The generation of boundary-derived neurospheres from hindbrain cultures confirmed the typical NSC behavior of boundary cells as a multipotent and self-renewing Sox2+ cell population. Inhibition of Sox2 in boundaries led to enhanced and aberrant neural differentiation together with inhibition in cell-proliferation, whereas Sox2 mis-expression attenuated neurogenesis, confirming its significant function in hindbrain neuronal organization. Conclusions Data obtained in this study deciphers a novel role of hindbrain boundaries as repetitive pools of neural stem/progenitor cells, which provide proliferating progenitors and differentiating neurons in a Sox2-dependent regulation. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0277-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yuval Peretz
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Noa Eren
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Ayelet Kohl
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Gideon Hen
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Karina Yaniv
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Karen Weisinger
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA
| | - Yuval Cinnamon
- Institute of Animal Sciences, Department of Poultry and Aquaculture Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
| | - Dalit Sela-Donenfeld
- Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel.
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Retinoic Acid Signaling Mediates Hair Cell Regeneration by Repressing p27kip and sox2 in Supporting Cells. J Neurosci 2016; 35:15752-66. [PMID: 26609166 DOI: 10.1523/jneurosci.1099-15.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED During development, otic sensory progenitors give rise to hair cells and supporting cells. In mammalian adults, differentiated and quiescent sensory cells are unable to generate new hair cells when these are lost due to various insults, leading to irreversible hearing loss. Retinoic acid (RA) has strong regenerative capacity in several organs, but its role in hair cell regeneration is unknown. Here, we use genetic and pharmacological inhibition to show that the RA pathway is required for hair cell regeneration in zebrafish. When regeneration is induced by laser ablation in the inner ear or by neomycin treatment in the lateral line, we observe rapid activation of several components of the RA pathway, with dynamics that position RA signaling upstream of other signaling pathways. We demonstrate that blockade of the RA pathway impairs cell proliferation of supporting cells in the inner ear and lateral line. Moreover, in neuromast, RA pathway regulates the transcription of p27(kip) and sox2 in supporting cells but not fgf3. Finally, genetic cell-lineage tracing using Kaede photoconversion demonstrates that de novo hair cells derive from FGF-active supporting cells. Our findings reveal that RA has a pivotal role in zebrafish hair cell regeneration by inducing supporting cell proliferation, and shed light on the underlying transcriptional mechanisms involved. This signaling pathway might be a promising approach for hearing recovery. SIGNIFICANCE STATEMENT Hair cells are the specialized mechanosensory cells of the inner ear that capture auditory and balance sensory input. Hair cells die after acoustic trauma, ototoxic drugs or aging diseases, leading to progressive hearing loss. Mammals, in contrast to zebrafish, lack the ability to regenerate hair cells. Here, we find that retinoic acid (RA) pathway is required for hair cell regeneration in vivo in the zebrafish inner ear and lateral line. RA pathway is activated very early upon hair cell loss, promotes cell proliferation of progenitor cells, and regulates two key genes, p27(kip) and sox2. Our results position RA as an essential signal for hair cell regeneration with relevance in future regenerative strategies in mammals.
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11
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Dyer C, Blanc E, Stanley RJ, Knight RD. Dissecting the role of Wnt signaling and its interactions with FGF signaling during midbrain neurogenesis. NEUROGENESIS 2015; 2:e1057313. [PMID: 27606327 PMCID: PMC4973611 DOI: 10.1080/23262133.2015.1057313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/07/2015] [Accepted: 05/27/2015] [Indexed: 11/14/2022]
Abstract
Interactions between FGF and Wnt/ bcat signaling control development of the midbrain. The nature of this interaction and how these regulate patterning, growth and differentiation is less clear, as it has not been possible to temporally dissect the effects of one pathway relative to the other. We have employed pharmacological and genetic tools to probe the temporal and spatial roles of FGF and Wnt in controlling the specification of early midbrain neurons. We identify a β-catenin (bcat) independent role for GSK-3 in modulating FGF activity and hence neuronal patterning. This function is complicated by an overlap with bcat-dependent regulation of FGF signaling, through the regulation of sprouty4. Additionally we reveal how attenuation of Axin protein function can promote fluctuating levels of bcat activity that are dependent on FGF activity. This highlights the complex nature of the interactions between FGF and Wnt/ bcat and reveals that they act at multiple levels to control each others activity in the midbrain.
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Affiliation(s)
- Carlene Dyer
- Craniofacial Development and Stem Cell Biology; King's College London ; London, UK
| | - Eric Blanc
- MRC Centre for Developmental Neurobiology; King's College London ; London, UK
| | - Rob J Stanley
- Department of Cell and Developmental Biology; University College London; London, UK; CoMPLEX; University College London; London, UK
| | - Robert D Knight
- Craniofacial Development and Stem Cell Biology; King's College London ; London, UK
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12
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Vega‐López GA, Bonano M, Tríbulo C, Fernández JP, Agüero TH, Aybar MJ. Functional analysis of
Hairy
genes in
Xenopus
neural crest initial specification and cell migration. Dev Dyn 2015; 244:988-1013. [DOI: 10.1002/dvdy.24295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 04/25/2015] [Accepted: 05/14/2015] [Indexed: 01/28/2023] Open
Affiliation(s)
| | - Marcela Bonano
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
| | - Celeste Tríbulo
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
- Instituto de Biología “Dr. Francisco D. Barbieri”, Facultad de Bioquímica, Química y FarmaciaUniversidad Nacional de TucumánChacabuco San Miguel de Tucumán Argentina
| | - Juan P. Fernández
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
| | - Tristán H. Agüero
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
| | - Manuel J. Aybar
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET‐UNT
- Instituto de Biología “Dr. Francisco D. Barbieri”, Facultad de Bioquímica, Química y FarmaciaUniversidad Nacional de TucumánChacabuco San Miguel de Tucumán Argentina
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13
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The transcription factor hairy/E(spl)-related 2 induces proliferation of neural progenitors and regulates neurogenesis and gliogenesis. Dev Biol 2014; 397:116-28. [PMID: 25446033 DOI: 10.1016/j.ydbio.2014.10.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 02/06/2023]
Abstract
The study of molecular regulation in neural development provides information to understand how diverse neural cells are generated. It also helps to establish therapeutic strategies for the treatment of neural degenerative disorders and brain tumors. The Hairy/E(spl) family members are potential targets of Notch signaling, which is fundamental to neural cell maintenance, cell fate decisions, and compartment boundary formation. In this study, we isolated a zebrafish homolog of Hairy/E(spl), her2, and showed that this gene is expressed in neural progenitor cells and in the developing nervous system. The expression of her2 required Notch activation, as revealed by a Notch-defective mutant and a chemical inhibitor, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). The endogenous expression of Her2 was altered by both overexpression and morpholino-knockdown approaches, and the results demonstrated that Her2 was both necessary and sufficient to promote the proliferation of neural progenitors by inhibiting the transcription of the cell cycle inhibitors cdkn1a, cdkn1ba, and cdkn1bb. Her2 knockdown caused premature neuronal differentiation, which indicates that Her2 is essential for inhibiting neuronal differentiation. At a later stage of neural development, Her2 could induce glial differentiation. The overexpression of Her2 constructs lacking the bHLH or WRPW domain phenocopied the effect of the morpholino knockdown, demonstrating the essential function of these two domains and further confirming the knockdown specificity. In conclusion, our data reveal that Her2 promotes progenitor proliferation and maintains progenitor characteristics by inhibiting neuronal differentiation. Together, these two mechanisms ensure the proper development of the neural progenitor cell pool.
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14
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Dirian L, Galant S, Coolen M, Chen W, Bedu S, Houart C, Bally-Cuif L, Foucher I. Spatial regionalization and heterochrony in the formation of adult pallial neural stem cells. Dev Cell 2014; 30:123-36. [PMID: 25017692 DOI: 10.1016/j.devcel.2014.05.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 03/25/2014] [Accepted: 05/14/2014] [Indexed: 01/10/2023]
Abstract
Little is known on the embryonic origin and related heterogeneity of adult neural stem cells (aNSCs). We use conditional genetic tracing, activated in a global or mosaic fashion by cell type-specific promoters or focal laser uncaging, coupled with gene expression analyses and Notch invalidations, to address this issue in the zebrafish adult telencephalon. We report that the germinal zone of the adult pallium originates from two distinct subtypes of embryonic progenitors and integrates two modes of aNSC formation. Dorsomedial aNSCs derive from the amplification of actively neurogenic radial glia of the embryonic telencephalon. On the contrary, the lateral aNSC population is formed by stepwise addition at the pallial edge from a discrete neuroepithelial progenitor pool of the posterior telencephalic roof, activated at postembryonic stages and persisting lifelong. This dual origin of the pallial germinal zone allows the temporally organized building of pallial territories as a patchwork of juxtaposed compartments.
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Affiliation(s)
- Lara Dirian
- Institute of Neurobiology A. Fessard, Laboratory of Neurobiology and Development, CNRS UPR3294, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Building 5, 91198 Gif-sur-Yvette, France
| | - Sonya Galant
- Institute of Neurobiology A. Fessard, Laboratory of Neurobiology and Development, CNRS UPR3294, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Building 5, 91198 Gif-sur-Yvette, France
| | - Marion Coolen
- Institute of Neurobiology A. Fessard, Laboratory of Neurobiology and Development, CNRS UPR3294, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Building 5, 91198 Gif-sur-Yvette, France
| | - Wenbiao Chen
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 2213 Garland Ave, Nashville, TN 37232, USA
| | - Sébastien Bedu
- Institute of Neurobiology A. Fessard, Laboratory of Neurobiology and Development, CNRS UPR3294, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Building 5, 91198 Gif-sur-Yvette, France
| | - Corinne Houart
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
| | - Laure Bally-Cuif
- Institute of Neurobiology A. Fessard, Laboratory of Neurobiology and Development, CNRS UPR3294, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Building 5, 91198 Gif-sur-Yvette, France.
| | - Isabelle Foucher
- Institute of Neurobiology A. Fessard, Laboratory of Neurobiology and Development, CNRS UPR3294, Team Zebrafish Neurogenetics, Avenue de la Terrasse, Building 5, 91198 Gif-sur-Yvette, France.
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15
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Dyer C, Blanc E, Hanisch A, Roehl H, Otto GW, Yu T, Basson MA, Knight R. A bi-modal function of Wnt signalling directs an FGF activity gradient to spatially regulate neuronal differentiation in the midbrain. Development 2013; 141:63-72. [PMID: 24284206 DOI: 10.1242/dev.099507] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
FGFs and Wnts are important morphogens during midbrain development, but their importance and potential interactions during neurogenesis are poorly understood. We have employed a combination of genetic and pharmacological manipulations in zebrafish to show that during neurogenesis FGF activity occurs as a gradient along the anterior-posterior axis of the dorsal midbrain and directs spatially dynamic expression of the Hairy gene her5. As FGF activity diminishes during development, Her5 is lost and differentiation of neuronal progenitors occurs in an anterior-posterior manner. We generated mathematical models to explain how Wnt and FGFs direct the spatial differentiation of neurons in the midbrain through Wnt regulation of FGF signalling. These models suggested that a negative-feedback loop controlled by Wnt is crucial for regulating FGF activity. We tested Sprouty genes as mediators of this regulatory loop using conditional mouse knockouts and pharmacological manipulations in zebrafish. These reveal that Sprouty genes direct the positioning of early midbrain neurons and are Wnt responsive in the midbrain. We propose a model in which Wnt regulates FGF activity at the isthmus by driving both FGF and Sprouty gene expression. This controls a dynamic, posteriorly retracting expression of her5 that directs neuronal differentiation in a precise spatiotemporal manner in the midbrain.
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Affiliation(s)
- Carlene Dyer
- Craniofacial Development and Stem Cell Biology, King's College London, Guy's Hospital, London SE1 9RT, UK
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16
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Dworkin S, Jane SM. Novel mechanisms that pattern and shape the midbrain-hindbrain boundary. Cell Mol Life Sci 2013; 70:3365-74. [PMID: 23307071 PMCID: PMC11113640 DOI: 10.1007/s00018-012-1240-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/18/2012] [Accepted: 12/10/2012] [Indexed: 12/27/2022]
Abstract
The midbrain-hindbrain boundary (MHB) is a highly conserved vertebrate signalling centre, acting to pattern and establish neural identities within the brain. While the core signalling pathways regulating MHB formation have been well defined, novel genetic and mechanistic processes that interact with these core components are being uncovered, helping to further elucidate the complicated networks governing MHB specification, patterning and shaping. Although formation of the MHB organiser is traditionally thought of as comprising three stages, namely positioning, induction and maintenance, we propose that a fourth stage, morphogenesis, should be considered as an additional stage in MHB formation. This review will examine evidence for novel factors regulating the first three stages of MHB development and will explore the evidence for regulation of MHB morphogenesis by non-classical MHB-patterning genes.
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Affiliation(s)
- Sebastian Dworkin
- Department of Medicine, Monash University Central Clinical School, Melbourne, VIC, 3004, Australia.
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17
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Gerety SS, Breau MA, Sasai N, Xu Q, Briscoe J, Wilkinson DG. An inducible transgene expression system for zebrafish and chick. Development 2013; 140:2235-43. [PMID: 23633515 DOI: 10.1242/dev.091520] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have generated an inducible system to control the timing of transgene expression in zebrafish and chick. An estrogen receptor variant (ERT2) fused to the GAL4 transcriptional activator rapidly and robustly activates transcription within 3 hours of treatment with the drug 4-hydroxy-tamoxifen (4-OHT) in tissue culture and transgenic zebrafish. We have generated a broadly expressed inducible ERT2-GAL4 zebrafish line using the ubiquitin (ubi) enhancer. In addition, use of ERT2-GAL4 in conjunction with tissue-specific enhancers enables the control of transgene expression in both space and time. This spatial restriction and the ability to sustain forced expression are important advantages over the currently used heat-shock promoters. Moreover, in contrast to currently available TET and LexA systems, which require separate constructs with their own unique recognition sequences, ERT2-GAL4 is compatible with the growing stock of UAS lines being generated in the community. We also applied the same inducible system to the chick embryo and find that it is fully functional, suggesting that this strategy is generally applicable.
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Affiliation(s)
- Sebastian S Gerety
- MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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18
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Schmidt R, Strähle U, Scholpp S. Neurogenesis in zebrafish - from embryo to adult. Neural Dev 2013; 8:3. [PMID: 23433260 PMCID: PMC3598338 DOI: 10.1186/1749-8104-8-3] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/17/2013] [Indexed: 01/19/2023] Open
Abstract
Neurogenesis in the developing central nervous system consists of the induction and proliferation of neural progenitor cells and their subsequent differentiation into mature neurons. External as well as internal cues orchestrate neurogenesis in a precise temporal and spatial way. In the last 20 years, the zebrafish has proven to be an excellent model organism to study neurogenesis in the embryo. Recently, this vertebrate has also become a model for the investigation of adult neurogenesis and neural regeneration. Here, we summarize the contributions of zebrafish in neural development and adult neurogenesis.
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Affiliation(s)
- Rebecca Schmidt
- Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, 76021, Karlsruhe, Germany
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19
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Dworkin S, Jane SM. Novel mechanisms that pattern and shape the midbrain-hindbrain boundary. CELLULAR AND MOLECULAR LIFE SCIENCES : CMLS 2013. [PMID: 23307071 DOI: 10.1007/s00018‐012‐1240‐x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The midbrain-hindbrain boundary (MHB) is a highly conserved vertebrate signalling centre, acting to pattern and establish neural identities within the brain. While the core signalling pathways regulating MHB formation have been well defined, novel genetic and mechanistic processes that interact with these core components are being uncovered, helping to further elucidate the complicated networks governing MHB specification, patterning and shaping. Although formation of the MHB organiser is traditionally thought of as comprising three stages, namely positioning, induction and maintenance, we propose that a fourth stage, morphogenesis, should be considered as an additional stage in MHB formation. This review will examine evidence for novel factors regulating the first three stages of MHB development and will explore the evidence for regulation of MHB morphogenesis by non-classical MHB-patterning genes.
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Affiliation(s)
- Sebastian Dworkin
- Department of Medicine, Monash University Central Clinical School, Melbourne, VIC, 3004, Australia.
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20
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Parain K, Mazurier N, Bronchain O, Borday C, Cabochette P, Chesneau A, Colozza G, El Yakoubi W, Hamdache J, Locker M, Gilchrist MJ, Pollet N, Perron M. A large scale screen for neural stem cell markers in Xenopus retina. Dev Neurobiol 2012; 72:491-506. [PMID: 22275214 DOI: 10.1002/dneu.20973] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Neural stem cell research suffers from a lack of molecular markers to specifically assess stem or progenitor cell properties. The organization of the Xenopus ciliary marginal zone (CMZ) in the retina allows the spatial distinction of these two cell types: stem cells are confined to the most peripheral region, while progenitors are more central. Despite this clear advantage, very few genes specifically expressed in retinal stem cells have been discovered so far in this model. To gain insight into the molecular signature of these cells, we performed a large-scale expression screen in the Xenopus CMZ, establishing it as a model system for stem cell gene profiling. Eighteen genes expressed specifically in the CMZ stem cell compartment were retrieved and are discussed here. These encode various types of proteins, including factors associated with proliferation, mitotic spindle organization, DNA/RNA processing, and cell adhesion. In addition, the publication of this work in a special issue on Xenopus prompted us to give a more general illustration of the value of large-scale screens in this model species. Thus, beyond neural stem cell specific genes, we give a broader highlight of our screen outcome, describing in particular other retinal cell markers that we found. Finally, we present how these can all be easily retrieved through a novel module we developed in the web-based annotation tool XenMARK, and illustrate the potential of this powerful searchable database in the context of the retina.
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Affiliation(s)
- Karine Parain
- Neurobiology and Development Laboratory, CNRS UPR 3294, Univ Paris-Sud, Orsay, France
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21
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Broom ER, Gilthorpe JD, Butts T, Campo-Paysaa F, Wingate RJT. The roof plate boundary is a bi-directional organiser of dorsal neural tube and choroid plexus development. Development 2012; 139:4261-70. [PMID: 23052907 DOI: 10.1242/dev.082255] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The roof plate is a signalling centre positioned at the dorsal midline of the central nervous system and generates dorsalising morphogenic signals along the length of the neuraxis. Within cranial ventricles, the roof plate gives rise to choroid plexus, which regulates the internal environment of the developing and adult brain and spinal cord via the secretion of cerebrospinal fluid. Using the fourth ventricle as our model, we show that the organiser properties of the roof plate are determined by its boundaries with the adjacent neuroepithelium. Through a combination of in ovo transplantation, co-culture and electroporation techniques in chick embryos between embryonic days 3 and 6, we demonstrate that organiser properties are maintained by interactions between the non-neural roof plate and the neural rhombic lip. At the molecular level, this interaction is mediated by Delta-Notch signalling and upregulation of the chick homologue of Hes1: chairy2. Gain- and loss-of-function approaches reveal that cdelta1 is both necessary and sufficient for organiser function. Our results also demonstrate that while chairy2 is specifically required for the maintenance of the organiser, its ectopic expression is not sufficient to recapitulate organiser properties. Expression of atonal1 in the rhombic lip adjacent at the roof plate boundary is acutely dependent on both boundary cell interactions and Delta-Notch signalling. Correspondingly, the roof plate boundary organiser also signals to the roof plate itself to specify the expression of early choroid plexus markers. Thus, the roof plate boundary organiser signals bi-directionally to acutely coordinate the development of adjacent neural and non-neural tissues.
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Affiliation(s)
- Emma R Broom
- MRC Centre for Developmental Neurobiology, King's College London, London, UK
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22
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Abstract
The cerebellum controls smooth and skillful movements and it is also involved in higher cognitive and emotional functions. The cerebellum is derived from the dorsal part of the anterior hindbrain and contains two groups of cerebellar neurons: glutamatergic and gamma-aminobutyric acid (GABA)ergic neurons. Purkinje cells are GABAergic and granule cells are glutamatergic. Granule and Purkinje cells receive input from outside of the cerebellum from mossy and climbing fibers. Genetic analysis of mice and zebrafish has revealed genetic cascades that control the development of the cerebellum and cerebellar neural circuits. During early neurogenesis, rostrocaudal patterning by intrinsic and extrinsic factors, such as Otx2, Gbx2 and Fgf8, plays an important role in the positioning and formation of the cerebellar primordium. The cerebellar glutamatergic neurons are derived from progenitors in the cerebellar rhombic lip, which express the proneural gene Atoh1. The GABAergic neurons are derived from progenitors in the ventricular zone, which express the proneural gene Ptf1a. The mossy and climbing fiber neurons originate from progenitors in the hindbrain rhombic lip that express Atoh1 or Ptf1a. Purkinje cells exhibit mediolateral compartmentalization determined on the birthdate of Purkinje cells, and linked to the precise neural circuitry formation. Recent studies have shown that anatomy and development of the cerebellum is conserved between mammals and bony fish (teleost species). In this review, we describe the development of cerebellar neurons and neural circuitry, and discuss their evolution by comparing developmental processes of mammalian and teleost cerebellum.
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Affiliation(s)
- Mitsuhiro Hashimoto
- Department of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, Aichi, 466-8550, Japan.
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23
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Terriente J, Gerety SS, Watanabe-Asaka T, Gonzalez-Quevedo R, Wilkinson DG. Signalling from hindbrain boundaries regulates neuronal clustering that patterns neurogenesis. Development 2012; 139:2978-87. [PMID: 22764046 DOI: 10.1242/dev.080135] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
During central nervous system development, neural progenitors are patterned to form discrete neurogenic and non-neurogenic zones. In the zebrafish hindbrain, neurogenesis is organised by Fgf20a emanating from neurons located at each segment centre that inhibits neuronal differentiation in adjacent progenitors. Here, we have identified a molecular mechanism that clusters fgf20a-expressing neurons in segment centres and uncovered a requirement for this positioning in the regulation of neurogenesis. Disruption of hindbrain boundary cell formation alters the organisation of fgf20a-expressing neurons, consistent with a role of chemorepulsion from boundaries. The semaphorins Sema3fb and Sema3gb, which are expressed by boundary cells, and their receptor Nrp2a are required for clustering of fgf20a-expressing neurons at segment centres. The dispersal of fgf20a-expressing neurons that occurs following the disruption of boundaries or of Sema3fb/Sema3gb signalling leads to reduced FGF target gene expression in progenitors and an increased number of differentiating neurons. Sema3 signalling from boundaries thus links hindbrain segmentation to the positioning of fgf20a-expressing neurons that regulates neurogenesis.
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Affiliation(s)
- Javier Terriente
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
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24
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Mukherjee A, Subhedar NK, Ghose A. Ontogeny of the cocaine- and amphetamine-regulated transcript (CART) neuropeptide system in the brain of zebrafish, Danio rerio. J Comp Neurol 2012; 520:770-97. [PMID: 22009187 DOI: 10.1002/cne.22779] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cocaine- and amphetamine-regulated transcript (CART) peptidergic system is involved in processing diverse neuronal functions in adult animals, including energy metabolism. Although CART is widely distributed in the brain of a range of vertebrates, the ontogeny of this system has not been explored. The CART-immunoreactive system in the zebrafish central nervous system (CNS) was studied across developmental stages until adulthood. The peptide is expressed as early as 24 hours post fertilization and establishes itself in several discrete areas of the brain and spinal cord as development progresses. The trends in CART ontogeny suggest that it may be involved in the establishment of commissural tracts, typically expressing early but subsequently decaying. CART elements are commonly overrepresented in diverse sensory areas like the olfactory, photic, and acoustico-mechanosensory systems, perhaps indicating a role for the peptide in sensory perception. Key neuroendocrine centers, like the preoptic area, hypothalamus, and pituitary, conspicuously show CART innervations, suggesting functions analogous to those demonstrated in other chordates. Uniquely, the epiphysis also appears to employ CART as a neurotransmitter. The entopeduncular nucleus is a major CART-containing group in the adult teleost forebrain that may participate in glucose sensing. This region responds to glucose in the 15-day larvae, suggesting that the energy status sensing CART circuits is active early in development. The pattern of CART expression in zebrafish suggests conserved evolutionary trends among vertebrate species. Developmental expression profiling reveals putative novel functions and establishes zebrafish as a model to investigate CART function in physiology and development.
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Affiliation(s)
- Arghya Mukherjee
- Indian Institute of Science Education and Research Pune, Pashan, Pune 411021, India
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25
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Chapouton P, Webb KJ, Stigloher C, Alunni A, Adolf B, Hesl B, Topp S, Kremmer E, Bally-Cuif L. Expression of hairy/enhancer of split genes in neural progenitors and neurogenesis domains of the adult zebrafish brain. J Comp Neurol 2012; 519:1748-69. [PMID: 21452233 DOI: 10.1002/cne.22599] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All subdivisions of the adult zebrafish brain maintain niches of constitutive neurogenesis, sustained by quiescent and multipotent progenitor populations. In the telencephalon, the latter potential neural stem cells take the shape of radial glia aligned along the ventricle and are controlled by Notch signalling. With the aim of identifying new markers of this cell type and of comparing the effectors of embryonic and adult neurogenesis, we focused on the family of hairy/enhancer of split [E(spl)] genes. We report the expression of seven hairy/E(spl) (her) genes and the new helt gene in three neurogenic areas of the adult zebrafish brain (telencephalon, hypothalamus, and midbrain) in relation to radial glia, proliferation, and neurogenesis. We show that the expression of most her genes in the adult brain characterizes quiescent radial glia, whereas only few are expressed in progenitor domains engaged in active proliferation or neurogenesis. The low proliferation status of most her-positive progenitors contrasts with the embryonic nervous system, in which her genes are expressed in actively dividing progenitors. Likewise, we demonstrate largely overlapping expression domains of a set of her genes in the adult brain, which is in striking contrast to their distinct embryonic expression profiles. Overall, our data provide a consolidated map of her expression, quiescent glia, proliferation, and neurogenesis in these various subdivisions of the adult brain and suggest distinct regulation and function of Her factors in the embryonic and adult contexts.
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Affiliation(s)
- Prisca Chapouton
- Zebrafish Neurogenetics Department, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
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26
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Kizil C, Kaslin J, Kroehne V, Brand M. Adult neurogenesis and brain regeneration in zebrafish. Dev Neurobiol 2012; 72:429-61. [DOI: 10.1002/dneu.20918] [Citation(s) in RCA: 249] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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27
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Cavodeassi F, Houart C. Brain regionalization: Of signaling centers and boundaries. Dev Neurobiol 2012; 72:218-33. [DOI: 10.1002/dneu.20938] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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28
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Hibi M, Shimizu T. Development of the cerebellum and cerebellar neural circuits. Dev Neurobiol 2012; 72:282-301. [DOI: 10.1002/dneu.20875] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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29
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Inui M, Montagner M, Piccolo S. miRNAs and morphogen gradients. Curr Opin Cell Biol 2011; 24:194-201. [PMID: 22196932 DOI: 10.1016/j.ceb.2011.11.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 11/16/2011] [Accepted: 11/30/2011] [Indexed: 01/05/2023]
Abstract
Morphogens induce biological diversity by operating in a dose-dependent manner. Here we review recent evidences indicating that microRNAs (miRNAs) are ideally suited to serve the morphogen cause. miRNAs regulate the establishment of morphogen gradients, including TGFβ, Wnt and other growth factors by acting on their secretion, distribution and clearance. miRNA are also critical in receiving cells, establishing context-dependency and threshold responses. Moreover, miRNAs contributes to gene networks that transform the graded activity of a morphogen into robust cell fate decisions. Finally, we discuss in the perspective section the implication of the new ceRNA hypothesis for morphogen biology.
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Affiliation(s)
- Masafumi Inui
- Department of Biomedical Sciences, University of Padua, Italy
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30
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Webb KJ, Coolen M, Gloeckner CJ, Stigloher C, Bahn B, Topp S, Ueffing M, Bally-Cuif L. The Enhancer of split transcription factor Her8a is a novel dimerisation partner for Her3 that controls anterior hindbrain neurogenesis in zebrafish. BMC DEVELOPMENTAL BIOLOGY 2011; 11:27. [PMID: 21586122 PMCID: PMC3125270 DOI: 10.1186/1471-213x-11-27] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 05/17/2011] [Indexed: 12/31/2022]
Abstract
Background Neurogenesis control and the prevention of premature differentiation in the vertebrate embryo are crucial processes, allowing the formation of late-born cell types and ensuring the correct shape and cytoarchitecture of the brain. Members of the Hairy/Enhancer of Split (Hairy/E(spl)) family of bHLH-Orange transcription factors, such as zebrafish Her3, 5, 9 and 11, are implicated in the local inhibition of neurogenesis to maintain progenitor pools within the early neural plate. To better understand how these factors exert their inhibitory function, we aimed to isolate some of their functional interactors. Results We used a yeast two-hybrid screen with Her5 as bait and recovered a novel zebrafish Hairy/E(spl) factor - Her8a. Using phylogenetic and synteny analyses, we demonstrate that her8a evolved from an ancient duplicate of Hes6 that was recently lost in the mammalian lineage. We show that her8a is expressed across the mid- and anterior hindbrain from the start of segmentation. Through knockdown and misexpression experiments, we demonstrate that Her8a is a negative regulator of neurogenesis and plays an essential role in generating progenitor pools within rhombomeres 2 and 4 - a role resembling that of Her3. Her8a co-purifies with Her3, suggesting that Her8a-Her3 heterodimers may be relevant in this domain of the neural plate, where both proteins are co-expressed. Finally, we demonstrate that her8a expression is independent of Notch signaling at the early neural plate stage but that SoxB factors play a role in its expression, linking patterning information to neurogenesis control. Overall, the regulation and function of Her8a differ strikingly from those of its closest relative in other vertebrates - the Hes6-like proteins. Conclusions Our results characterize the phylogeny, expression and functional interactions involving a new Her factor, Her8a, and highlight the complex interplay of E(spl) proteins that generates the neurogenesis pattern of the zebrafish early neural plate.
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Affiliation(s)
- Katharine J Webb
- Zebrafish Neurogenetics Department, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstr, 1, D-85764 Neuherberg, Germany.
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Bonev B, Pisco A, Papalopulu N. MicroRNA-9 reveals regional diversity of neural progenitors along the anterior-posterior axis. Dev Cell 2011; 20:19-32. [PMID: 21238922 PMCID: PMC3361082 DOI: 10.1016/j.devcel.2010.11.018] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 10/11/2010] [Accepted: 11/19/2010] [Indexed: 12/19/2022]
Abstract
Neural progenitors self-renew and generate neurons throughout the central nervous system. Here, we uncover an unexpected regional specificity in the properties of neural progenitor cells, revealed by the function of a microRNA—miR-9. miR-9 is expressed in neural progenitors, and its knockdown results in an inhibition of neurogenesis along the anterior-posterior axis. However, the underlying mechanism differs—in the hindbrain, progenitors fail to exit the cell cycle, whereas in the forebrain they undergo apoptosis, counteracting the proliferative effect. Among several targets, we functionally identify hairy1 as a primary target of miR-9, regulated at the mRNA level. hairy1 mediates the effects of miR-9 on proliferation, through Fgf8 signaling in the forebrain and Wnt signaling in the hindbrain, but affects apoptosis only in the forebrain, via the p53 pathway. Our findings show a positional difference in the responsiveness of progenitors to miR-9 depletion, revealing an underlying divergence of their properties.
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Affiliation(s)
- Boyan Bonev
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
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Feijóo CG, Oñate MG, Milla LA, Palma VA. Sonic hedgehog (Shh)-Gli signaling controls neural progenitor cell division in the developing tectum in zebrafish. Eur J Neurosci 2011; 33:589-98. [PMID: 21219478 DOI: 10.1111/j.1460-9568.2010.07560.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Despite considerable progress, the mechanisms that control neural progenitor differentiation and behavior, as well as their functional integration into adult neural circuitry, are far from being understood. Given the complexity of the mammalian brain, non-mammalian models provide an excellent model to study neurogenesis, including both the cellular composition of the neurogenic microenvironment, and the factors required for precursor growth and maintenance. In particular, we chose to address the question of the control of progenitor proliferation by Sonic hedgehog (Shh) using the zebrafish dorsal mesencephalon, known as the optic tectum (OT), as a model system. Here we show that either inhibiting pharmacologically or eliminating hedgehog (Hh) signaling by using mutants that lack essential components of the Hh pathway reduces neural progenitor cell proliferation affecting neurogenesis in the OT. On the contrary, pharmacological gain-of-function experiments result in significant increase in proliferation. Importantly, Shh-dependent function controls neural progenitor cell behavior as sox2-positive cell populations were lost in the OT in the absence of Hh signaling, as evidenced in slow-muscle-omitted (smu) mutants and with timed cyclopamine inhibition. Expressions of essential components of the Hh pathway reveal for the first time a late dorsal expression in the embryonic OT. Our observations argue strongly for a role of Shh in neural progenitor biology in the OT and provide comparative data to our current understanding of progenitor/stem cell mechanisms that place Shh as a key niche factor in the dorsal brain.
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Affiliation(s)
- Carmen G Feijóo
- Center for Genomics of the Cell, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile
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33
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Hans S, Freudenreich D, Geffarth M, Kaslin J, Machate A, Brand M. Generation of a non-leaky heat shock-inducible Cre line for conditional Cre/lox strategies in zebrafish. Dev Dyn 2010; 240:108-15. [DOI: 10.1002/dvdy.22497] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Sobieszczuk DF, Poliakov A, Xu Q, Wilkinson DG. A feedback loop mediated by degradation of an inhibitor is required to initiate neuronal differentiation. Genes Dev 2010; 24:206-18. [PMID: 20080956 DOI: 10.1101/gad.554510] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Neuronal differentiation is regulated by proneural genes that promote neurogenesis and inhibitory mechanisms that maintain progenitors. This raises the question of how the up-regulation of proneural genes required to initiate neurogenesis occurs in the presence of such inhibition. We carried out loss and gain of gene function, an interaction screen for binding partners, and biochemical analyses to uncover the regulation, developmental role, and mechanism of action of a ubiquitination adaptor protein, Btbd6a (BTB domain containing 6a). We find that the proneural gene neurog1 up-regulates btbd6a, which in turn is required for up-regulation of neurog1. Btbd6a is an adaptor for the Cul3 ubiquitin ligase complex, and we find that it binds to the transcriptional repressor Plzf (promyelocytic leukemia zinc finger). Btbd6a promotes the relocation of Plzf from nucleus to cytoplasm and targets Plzf for ubiquitination and degradation. plzfa is expressed widely in the neural epithelium; when overexpressed, it inhibits neurogenesis, and this inhibition is reversed by btbd6a. The antagonism of endogenous plzfa by btbd6a is required for neurogenesis, since the block in neuronal differentiation caused by btbd6a knockdown is alleviated by plzfa knockdown. These findings reveal a feedback loop mediated by degradation of an inhibitor that is essential for progenitors to undergo the transition to neuronal differentiation.
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Affiliation(s)
- Dorothy F Sobieszczuk
- Division of Developmental Neurobiology, MRC National Institute for Medical Research, London NW7 1AA, United Kingdom
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35
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Gonzalez-Quevedo R, Lee Y, Poss KD, Wilkinson DG. Neuronal regulation of the spatial patterning of neurogenesis. Dev Cell 2010; 18:136-47. [PMID: 20152184 PMCID: PMC2822724 DOI: 10.1016/j.devcel.2009.11.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 10/05/2009] [Accepted: 11/13/2009] [Indexed: 11/25/2022]
Abstract
Precise regulation of neurogenesis is achieved in specific regions of the vertebrate nervous system by formation of distinct neurogenic and nonneurogenic zones. We have investigated how neurogenesis becomes confined to zones adjacent to rhombomere boundaries in the zebrafish hindbrain. The nonneurogenic zone at segment centers comprises a distinct progenitor population that expresses fibroblast growth factor (fgfr) 2, erm, sox9b, and the retinoic acid degrading enzyme, cyp26b1. FGF receptor activation upregulates expression of these genes and inhibits neurogenesis in segment centers. Cyp26 activity is a key effector inhibiting neuronal differentiation, suggesting antagonistic interactions with retinoid signaling. We identify the critical FGF ligand, fgf20a, which is expressed by specific neurons located in the mantle region at the center of segments, adjacent to the nonneurogenic zone. Fgf20a mutants have ectopic neurogenesis and lack the segment center progenitor population. Our findings reveal how signaling from neurons induces formation of a nonneurogenic zone of neural progenitors.
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Affiliation(s)
- Rosa Gonzalez-Quevedo
- Division of Developmental Neurobiology, Medical Research Council National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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36
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Abstract
For more than a decade, the zebrafish has proven to be an excellent model organism to investigate the mechanisms of neurogenesis during development. The often cited advantages, namely external development, genetic, and optical accessibility, have permitted direct examination and experimental manipulations of neurogenesis during development. Recent studies have begun to investigate adult neurogenesis, taking advantage of its widespread occurrence in the mature zebrafish brain to investigate the mechanisms underlying neural stem cell maintenance and recruitment. Here we provide a comprehensive overview of the tools and techniques available to study neurogenesis in zebrafish both during development and in adulthood. As useful resources, we provide tables of available molecular markers, transgenic, and mutant lines. We further provide optimized protocols for studying neurogenesis in the adult zebrafish brain, including in situ hybridization, immunohistochemistry, in vivo lipofection and electroporation methods to deliver expression constructs, administration of bromodeoxyuridine (BrdU), and finally slice cultures. These currently available tools have put zebrafish on par with other model organisms used to investigate neurogenesis.
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Affiliation(s)
- Prisca Chapouton
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
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37
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Her6 regulates the neurogenetic gradient and neuronal identity in the thalamus. Proc Natl Acad Sci U S A 2009; 106:19895-900. [PMID: 19903880 DOI: 10.1073/pnas.0910894106] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
During vertebrate brain development, the onset of neuronal differentiation is under strict temporal control. In the mammalian thalamus and other brain regions, neurogenesis is regulated also in a spatially progressive manner referred to as a neurogenetic gradient, the underlying mechanism of which is unknown. Here we describe the existence of a neurogenetic gradient in the zebrafish thalamus and show that the progression of neurogenesis is controlled by dynamic expression of the bHLH repressor her6. Members of the Hes/Her family are known to regulate proneural genes, such as Neurogenin and Ascl. Here we find that Her6 determines not only the onset of neurogenesis but also the identity of thalamic neurons, marked by proneural and neurotransmitter gene expression: loss of Her6 leads to premature Neurogenin1-mediated genesis of glutamatergic (excitatory) neurons, whereas maintenance of Her6 leads to Ascl1-mediated production of GABAergic (inhibitory) neurons. Thus, the presence or absence of a single upstream regulator of proneural gene expression, Her6, leads to the establishment of discrete neuronal domains in the thalamus.
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Russek-Blum N, Nabel-Rosen H, Levkowitz G. High resolution fate map of the zebrafish diencephalon. Dev Dyn 2009; 238:1827-35. [PMID: 19504459 DOI: 10.1002/dvdy.21987] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The diencephalon acts as an interactive site between the sensory, central, and endocrine systems and is one of the most elaborate structures in the vertebrate brain. To better understand the embryonic development and morphogenesis of the diencephalon, we developed an improved photoactivation (uncaging)-based lineage tracing strategy. To determine the exact position of a given diencephalic progenitor domain, we used a transgenic line driving green fluorescent protein (GFP) in cells expressing the proneural protein, Neurogenin1 (Neurog1), which was used as a visible neural plate landmark. This approach facilitated precise labeling of defined groups of cells in the prospective diencephalon of the zebrafish neural plate. In this manner, we labeled multiple overlapping areas of the diencephalon, thereby ensuring both accuracy and reproducibility of our lineage tracing regardless of the dynamic changes of the developing neural plate. We present a fate map of the zebrafish diencephalon at a higher spatial resolution than previously described.
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Affiliation(s)
- Niva Russek-Blum
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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39
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Ninkovic J, Stigloher C, Lillesaar C, Bally-Cuif L. Gsk3beta/PKA and Gli1 regulate the maintenance of neural progenitors at the midbrain-hindbrain boundary in concert with E(Spl) factor activity. Development 2008; 135:3137-48. [PMID: 18725518 DOI: 10.1242/dev.020479] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuronal production in the midbrain-hindbrain domain (MH) of the vertebrate embryonic neural tube depends on a progenitor pool called the ;intervening zone' (IZ), located at the midbrain-hindbrain boundary. The progressive recruitment of IZ progenitors along the mediolateral (future dorsoventral) axis prefigures the earlier maturation of the MH basal plate. It also correlates with a lower sensitivity of medial versus lateral IZ progenitors to the neurogenesis inhibition process that maintains the IZ pool. This role is performed in zebrafish by the E(Spl) factors Her5 and Her11, but the molecular cascades cooperating with Her5/11, and those accounting for their reduced effect in the medial IZ, remain unknown. We demonstrate here that the kinases Gsk3beta and cAMP-dependent protein kinase A (PKA) are novel determinants of IZ formation and cooperate with E(Spl) activity in a dose-dependent manner. Similar to E(Spl), we show that the activity of Gsk3beta/PKA is sensed differently by medial versus lateral IZ progenitors. Furthermore, we identify the transcription factor Gli1, expressed in medial IZ cells, as an antagonist of E(Spl) and Gsk3beta/PKA, and demonstrate that the neurogenesis-promoting activity of Gli1 accounts for the reduced sensitivity of medial IZ progenitors to neurogenesis inhibitors and their increased propensity to differentiate. We also show that the expression and activity of Gli1 in this process are, surprisingly, independent of Hedgehog signaling. Together, our results suggest a model in which the modulation of E(Spl) and Gsk3beta/PKA activities by Gli1 underlies the dynamic properties of IZ maintenance and recruitment.
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Affiliation(s)
- Jovica Ninkovic
- Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Department of Zebrafish Neurogenetics, Institute of Developmental Genetics, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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40
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Leucht C, Stigloher C, Wizenmann A, Klafke R, Folchert A, Bally-Cuif L. MicroRNA-9 directs late organizer activity of the midbrain-hindbrain boundary. Nat Neurosci 2008; 11:641-8. [PMID: 18454145 DOI: 10.1038/nn.2115] [Citation(s) in RCA: 239] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 03/24/2008] [Indexed: 12/22/2022]
Abstract
The midbrain-hindbrain boundary (MHB) is a long-lasting organizing center in the vertebrate neural tube that is both necessary and sufficient for the ordered development of midbrain and anterior hindbrain (midbrain-hindbrain domain, MH). The MHB also coincides with a pool of progenitor cells that contributes neurons to the entire MH. Here we show that the organizing activity and progenitor state of the MHB are co-regulated by a single microRNA, miR-9, during late embryonic development in zebrafish. Endogenous miR-9 expression, initiated at late stages, selectively spares the MHB. Gain- and loss-of-function studies, in silico predictions and sensor assays in vivo demonstrate that miR-9 targets several components of the Fgf signaling pathway, thereby delimiting the organizing activity of the MHB. In addition, miR-9 promotes progression of neurogenesis in the MH, defining the MHB progenitor pool. Together, these findings highlight a previously unknown mechanism by which a single microRNA fine-tunes late MHB coherence via its co-regulation of patterning activities and neurogenesis.
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Affiliation(s)
- Christoph Leucht
- Department of Zebrafish Neurogenetics, Institute of Developmental Genetics, Helmholtz-Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany
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41
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Shin CH, Chung WS, Hong SK, Ober EA, Verkade H, Field HA, Huisken J, Stainier DYR. Multiple roles for Med12 in vertebrate endoderm development. Dev Biol 2008; 317:467-79. [PMID: 18394596 DOI: 10.1016/j.ydbio.2008.02.031] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 02/14/2008] [Accepted: 02/15/2008] [Indexed: 02/02/2023]
Abstract
In zebrafish, the endoderm originates at the blastula stage from the most marginal blastomeres. Through a series of complex morphogenetic movements and differentiation events, the endodermal germ layer gives rise to the epithelial lining of the digestive tract as well as its associated organs such as the liver, pancreas, and swim bladder. How endodermal cells differentiate into distinct cell types such as hepatocytes or endocrine and exocrine pancreatic cells remains a major question. In a forward genetic screen for genes regulating endodermal organ development, we identified mutations at the shiri locus that cause defects in the development of a number of endodermal organs including the liver and pancreas. Detailed phenotypic analyses indicate that these defects are partially due to a reduction in endodermal expression of the hairy/enhancer of split-related gene, her5, at mid to late gastrulation stages. Using the Tg(0.7her5:EGFP)(ne2067) line, we show that her5 is expressed in the endodermal precursors that populate the pharyngeal region as well as the organ-forming region. We also find that knocking down her5 recapitulates some of the endodermal phenotypes of shiri mutants, further revealing the role of her5 in endoderm development. Positional cloning reveals that shiri encodes Med12, a regulatory subunit of the transcriptional Mediator complex recently associated with two human syndromes. Additional studies indicate that Med12 modulates the ability of Casanova/Sox32 to induce sox17 expression. Thus, detailed phenotypic analyses of embryos defective in a component of the Mediator complex have revealed new insights into discrete aspects of vertebrate endoderm development, and provide possible explanations for the craniofacial and digestive system defects observed in humans with mutations in MED12.
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Affiliation(s)
- Chong Hyun Shin
- Department of Biochemistry and Biophysics, Liver Center, University of California, San Francisco, CA 94158, USA.
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42
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Stigloher C, Chapouton P, Adolf B, Bally-Cuif L. Identification of neural progenitor pools by E(Spl) factors in the embryonic and adult brain. Brain Res Bull 2008; 75:266-73. [DOI: 10.1016/j.brainresbull.2007.10.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 10/17/2007] [Indexed: 11/26/2022]
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Abstract
Adult neurogenesis is an exciting and rapidly advancing field of research. It addresses basic biological questions, such as the how and why of de novo neuronal production during adulthood, as well as medically relevant issues, including the potential link between adult neural stem cells and psychiatric disorders, or how stem cell manipulation might be used as a strategy for neuronal replacement. Current research mainly focuses on rodents, but we review here recent examination of non-mammalian vertebrates, which demonstrates that bona fide adult neural stem cells exist in these species. Importantly, especially in teleost fish, these cells can be abundant and located in various brain areas. Hence, non-mammalian vertebrate species provide invaluable comparative material for extracting core mechanisms of adult neural stem cell maintenance and fate.
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Affiliation(s)
- Prisca Chapouton
- Department Zebrafish Neurogenetics, GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, Neuherberg, Germany
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44
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Nagatomo KI, Hashimoto C. Xenopus hairy2 functions in neural crest formation by maintaining cells in a mitotic and undifferentiated state. Dev Dyn 2007; 236:1475-83. [PMID: 17436284 DOI: 10.1002/dvdy.21152] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The neural crest is a population of mitotically active, multipotent progenitor cells that arise at the neural plate border. Neural crest progenitors must be maintained in a multipotent state until after neural tube closure. However, the molecular underpinnings of this process have yet to be fully elucidated. Here we show that the basic helix-loop-helix (bHLH) transcriptional repressor gene, Xenopus hairy2 (Xhairy2), is an essential early regulator of neural crest formation in Xenopus. During gastrulation, Xhairy2 is localized at the presumptive neural crest prior to the expression of such neural crest markers as Slug and FoxD3. Morpholino-mediated knockdown of Xhairy2 results in the repression of neural crest marker gene expression while inducing the ectopic expression of the cell cycle inhibitor p27(xic1) in the presumptive neural crest. We also found that ectopic p27(xic1) disturbs neural crest formation. Furthermore, the depletion of Xhairy2 leads to the apoptosis of mitotic cells. Our results suggest that Xhairy2 functions in neural crest specification by maintaining cells in the mitotic and undifferentiated state.
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Affiliation(s)
- Kan-Ichiro Nagatomo
- Department of Biology, Graduate School of Science, Osaka University, and JT Biohistory Research Hall, Osaka, Japan
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45
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Expression of the zebrafish intermediate neurofilament Nestin in the developing nervous system and in neural proliferation zones at postembryonic stages. BMC DEVELOPMENTAL BIOLOGY 2007; 7:89. [PMID: 17651502 PMCID: PMC1950091 DOI: 10.1186/1471-213x-7-89] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 07/25/2007] [Indexed: 11/29/2022]
Abstract
Background The intermediate filament Nestin has been reported as a marker for stem cells and specific precursor cell populations in the developing mammalian central nervous system (CNS). Nestin expressing precursors may give rise to neurons and glia. Mouse nestin expression starts at the onset of neurulation in the neuroectodermal cells and is dramatically down regulated when progenitor cells differentiate and become postmitotic. It has been reported that in the adult zebrafish (Danio rerio) active neurogenesis continues in all major subdivisions of the CNS, however few markers for zebrafish precursors cells are known, and Nestin has not been described in zebrafish. Results We cloned a zebrafish nestin gDNA fragment in order to find a marker for precursor cells in the developing and postembryonic brain. Phylogenetic tree analysis reveals that this zebrafish ortholog clusters with Nestin sequences from other vertebrates but not with other intermediate filament proteins. We analyzed nestin expression from gastrula stage to 4 day larvae, and in post-embryonic brains. We found broad expression in the neuroectoderm during somitogenesis. In the larvae, nestin expression progressively becomes restricted to all previously described proliferative zones of the developing and postembryonic central nervous system. nestin expressing cells of the forebrain also express PCNA during late embryogenesis, identifying them as proliferating precursor or neural stem cells. nestin is also expressed in the cranial ganglia, in mesodermal precursors of muscle cells, and in cranial mesenchymal tissue. Conclusion Our data demonstrate that in zebrafish, like in mammals, the expression of the intermediated neurofilament nestin gene may serve as a marker for stem cells and proliferating precursors in the developing embryonic nervous system as well as in the postembryonic brain.
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Abelló G, Khatri S, Giráldez F, Alsina B. Early regionalization of the otic placode and its regulation by the Notch signaling pathway. Mech Dev 2007; 124:631-45. [PMID: 17532192 DOI: 10.1016/j.mod.2007.04.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 04/11/2007] [Accepted: 04/13/2007] [Indexed: 01/30/2023]
Abstract
Otic neuronal precursors are the first cells to be specified and do so in the anterior domain of the otic placode, the proneural domain. In the present study, we have explored the early events of otic proneural regionalization in relation to the activity of the Notch signaling pathway. The proneural domain was characterized by the expression of Sox3, Fgf10 and members of the Notch pathway such as Delta1, Hes5 and Lunatic Fringe. The complementary non-neural domain expressed two patterning genes, Lmx1b and Iroquois1, and the members of the Notch pathway, Serrate1 and Hairy1. Fate map studies and double injections with DiI/DiO showed that labeled cells remained confined to anterior or posterior territories with limited cell intermingling. To explore whether Notch signaling pathway plays a role in the initial regionalization of the otic placode, Notch activity was blocked by a gamma-secretase inhibitor (DAPT). Notch blockade induced the expansion of non-neural genes, Lmx1 and Iroquois1, into the proneural domain. Combined gene expression and DiI experiments showed that these effects were not due to migration of non-neural cells into the proneural domain, suggesting that Notch activity regulates the expression of non-neural genes. This was further confirmed by the electroporation of a dominant-negative form of the Mastermind-like1 gene that caused the up-regulation of Lmx1 within the proneural domain. In addition, Notch pathway was involved in neuronal precursor selection, probably by a classical mechanism of lateral inhibition. We propose that the regionalization of the otic domain into a proneural and a non-neural territory is a very early event in otic development, and that Notch signaling activity is required to exclude the expression of non-neural genes from the proneural territory.
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Affiliation(s)
- Gina Abelló
- DCEXS-Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003 Barcelona, Spain
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47
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Shankaran SS, Sieger D, Schröter C, Czepe C, Pauly MC, Laplante MA, Becker TS, Oates AC, Gajewski M. Completing the set of h/E(spl) cyclic genes in zebrafish: her12 and her15 reveal novel modes of expression and contribute to the segmentation clock. Dev Biol 2007; 304:615-32. [PMID: 17274976 DOI: 10.1016/j.ydbio.2007.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 12/19/2006] [Accepted: 01/04/2007] [Indexed: 11/30/2022]
Abstract
Somitogenesis is the key developmental process that lays down the framework for a metameric body in vertebrates. Somites are generated from the un-segmented presomitic mesoderm (PSM) by a pre-patterning process driven by a molecular oscillator termed the segmentation clock. The Delta-Notch intercellular signaling pathway and genes belonging to the hairy (h) and Enhancer of split (E(spl))-related (h/E(spl)) family of transcriptional repressors are conserved components of this oscillator. A subset of these genes, called cyclic genes, is characterized by oscillating mRNA expression that sweeps anteriorly like a wave through the embryonic PSM. Periodic transcriptional repression by H/E(spl) proteins is thought to provide a critical part of a negative feedback loop in the oscillatory process, but it is an open question how many cyclic h/E(spl) genes are involved in the somitogenesis clock in any species, and what distinct roles they might play. From a genome-wide search for h/E(spl) genes in the zebrafish, we previously estimated a total of five cyclic members. Here we report that one of these, the mHes5 homologue her15 actually exists as a very recently duplicated gene pair. We investigate the expression of this gene pair and analyse its regulation and activity in comparison to the paralogous her12 gene, and the other cyclic h/E(spl) genes in the zebrafish. The her15 gene pair and her12 display novel and distinct expression features, including a caudally restricted oscillatory domain and dynamic stripes of expression in the rostral PSM that occur at the future segmental borders. her15 expression stripes demarcate a unique two-segment interval in the rostral PSM. Mutant, morpholino, and inhibitor studies show that her12 and her15 expression in the PSM is regulated by Delta-Notch signaling in a complex manner, and is dependent on her7, but not her1 function. Morpholino-mediated her12 knockdown disrupts cyclic gene expression, indicating that it is a non-redundant core component of the segmentation clock. Over-expression of her12, her15 or her7 disrupts cyclic gene expression and somite border formation, and structure function analysis of Her7 indicates that DNA binding, but not Groucho-recruitment seems to be important in this process. Thus, the zebrafish has five functional cyclic h/E(spl) genes, which are expressed in a distinct spatial configuration. We propose that this creates a segmentation oscillator that varies in biochemical composition depending on position in the PSM.
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Affiliation(s)
- Sunita S Shankaran
- Institute for Genetics, University of Cologne, Zülpicher Str. 47, 50674 Cologne, Germany
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48
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Kageyama R, Ohtsuka T, Kobayashi T. The Hes gene family: repressors and oscillators that orchestrate embryogenesis. Development 2007; 134:1243-51. [PMID: 17329370 DOI: 10.1242/dev.000786] [Citation(s) in RCA: 488] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Embryogenesis involves orchestrated processes of cell proliferation and differentiation. The mammalian Hes basic helix-loop-helix repressor genes play central roles in these processes by maintaining progenitor cells in an undifferentiated state and by regulating binary cell fate decisions. Hes genes also display an oscillatory expression pattern and control the timing of biological events, such as somite segmentation. Many aspects of Hes expression are regulated by Notch signaling, which mediates cell-cell communication. This primer describes these pleiotropic roles of Hes genes in some developmental processes and aims to clarify the basic mechanism of how gene networks operate in vertebrate embryogenesis.
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Affiliation(s)
- Ryoichiro Kageyama
- Institute for Virus Research, Kyoto University and Japan Science and Technology Agency, CREST, Kyoto 606-8507, Japan.
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49
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Chapouton P, Adolf B, Leucht C, Tannhäuser B, Ryu S, Driever W, Bally-Cuif L. her5 expression reveals a pool of neural stem cells in the adult zebrafish midbrain. Development 2007; 133:4293-303. [PMID: 17038515 DOI: 10.1242/dev.02573] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Current models of vertebrate adult neural stem cells are largely restricted to the rodent forebrain. To extract the general mechanisms of neural stem cell biology, we sought to identify new adult stem cell populations, in other model systems and/or brain areas. The teleost zebrafish appears to be an ideal system, as cell proliferation in the adult zebrafish brain is found in many more niches than in the mammalian brain. As a starting point towards identifying stem cell populations in this system, we used an embryonic neural stem cell marker, the E(spl) bHLH transcription factor Her5. We demonstrate that her5 expression is not restricted to embryonic neural progenitors, but also defines in the adult zebrafish brain a new proliferation zone at the junction between the mid- and hindbrain. We show that adult her5-expressing cells proliferate slowly, self-renew and express neural stem cell markers. Finally, using in vivo lineage tracing in her5:gfp transgenic animals, we demonstrate that the her5-positive population is multipotent, giving rise in situ to differentiated neurons and glia that populate the basal midbrain. Our findings conclusively identify a new population of adult neural stem cells, as well as their fate and their endogenous environment, in the intact vertebrate brain. This cell population, located outside the forebrain, provides a powerful model to assess the general mechanisms of vertebrate neural stem cell biology. In addition, the first transcription factor characteristic of this cell population, Her5, points to the E(Spl) as a promising family of candidate adult neural stem cell regulators.
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Affiliation(s)
- Prisca Chapouton
- Zebrafish Neurogenetics Junior Research Group, Institute of Virology, Technical University-Munich, Trogerstrasse 4b, D-81675, Munich, Germany.
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50
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Jukkola T, Lahti L, Naserke T, Wurst W, Partanen J. FGF regulated gene-expression and neuronal differentiation in the developing midbrain-hindbrain region. Dev Biol 2006; 297:141-57. [PMID: 16782087 DOI: 10.1016/j.ydbio.2006.05.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Revised: 04/03/2006] [Accepted: 05/03/2006] [Indexed: 11/23/2022]
Abstract
The neuroectodermal tissue close to the midbrain-hindbrain boundary (MHB) is an important secondary organizer in the developing neural tube. This so-called isthmic organizer (IsO) secretes signaling molecules, such as fibroblast growth factors (FGFs), which regulate cellular survival, patterning and proliferation in the midbrain and rhombomere 1 (R1) of the hindbrain. We have previously shown that FGF-receptor 1 (FGFR1) is required for the normal development of this brain region in the mouse embryo. Here, we have compared the gene expression profiles of midbrain-R1 tissues from wild-type embryos and conditional Fgfr1 mutants, in which FGFR1 is inactivated in the midbrain and R1. Loss of Fgfr1 results in the downregulation of several genes expressed close to the midbrain-hindbrain boundary and in the disappearance of gene expression gradients in the midbrain and anterior hindbrain. Our screen identified several previously uncharacterized genes which may participate in the development of midbrain-R1 region. Our results also show altered neurogenesis in the midbrain and R1 of the Fgfr1 mutants. Interestingly, the neuronal progenitors in midbrain and R1 show different responses to the loss of signaling through FGFR1.
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Affiliation(s)
- Tomi Jukkola
- Institute of Biotechnology, Viikki Biocenter, P.O. Box 56, 00014 University of Helsinki, Finland
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