1
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Cooper EJ, Scholpp S. Transport and gradient formation of Wnt and Fgf in the early zebrafish gastrula. Curr Top Dev Biol 2023; 157:125-153. [PMID: 38556457 DOI: 10.1016/bs.ctdb.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
Within embryonic development, the occurrence of gastrulation is critical in the formation of multiple germ layers with many differentiative abilities. These cells are instructed through exposure to signalling molecules called morphogens. The secretion of morphogens from a source tissue creates a concentration gradient that allows distinct pattern formation in the receiving tissue. This review focuses on the morphogens Wnt and Fgf in zebrafish development. Wnt has been shown to have critical roles throughout gastrulation, including in anteroposterior patterning and neural posterisation. Fgf is also a vital signal, contributing to involution and mesodermal specification. Both morphogens have also been found to work in finely balanced synergy for processes such as neural induction. Thus, the signalling range of Wnts and Fgfs must be strictly controlled to target the correct target cells. Fgf and Wnts signal to local cells as well as to cells in the distance in a highly regulated way, requiring specific dissemination mechanisms that allow efficient and precise signalling over short and long distances. Multiple transportation mechanisms have been discovered to aid in producing a stable morphogen gradient, including short-range diffusion, filopodia-like extensions called cytonemes and extracellular vesicles, mainly exosomes. These mechanisms are specific to the morphogen that they transport and the intended signalling range. This review article discusses how spreading mechanisms in these two morphogenetic systems differ and the consequences on paracrine signalling, hence tissue patterning.
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Affiliation(s)
- Emma J Cooper
- Living Systems Institute, Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Steffen Scholpp
- Living Systems Institute, Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom.
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2
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Bruet E, Amarante-Silva D, Gorojankina T, Creuzet S. The Emerging Roles of the Cephalic Neural Crest in Brain Development and Developmental Encephalopathies. Int J Mol Sci 2023; 24:9844. [PMID: 37372994 DOI: 10.3390/ijms24129844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023] Open
Abstract
The neural crest, a unique cell population originating from the primitive neural field, has a multi-systemic and structural contribution to vertebrate development. At the cephalic level, the neural crest generates most of the skeletal tissues encasing the developing forebrain and provides the prosencephalon with functional vasculature and meninges. Over the last decade, we have demonstrated that the cephalic neural crest (CNC) exerts an autonomous and prominent control on the development of the forebrain and sense organs. The present paper reviews the primary mechanisms by which CNC can orchestrate vertebrate encephalization. Demonstrating the role of the CNC as an exogenous source of patterning for the forebrain provides a novel conceptual framework with profound implications for understanding neurodevelopment. From a biomedical standpoint, these data suggest that the spectrum of neurocristopathies is broader than expected and that some neurological disorders may stem from CNC dysfunctions.
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Affiliation(s)
- Emmanuel Bruet
- Paris-Saclay Institute of Neuroscience, NeuroPSI, CNRS, Paris-Saclay University, Campus CEA Saclay, Bât 151, 151 Route de la Rotonde, 91400 Saclay, France
| | - Diego Amarante-Silva
- Paris-Saclay Institute of Neuroscience, NeuroPSI, CNRS, Paris-Saclay University, Campus CEA Saclay, Bât 151, 151 Route de la Rotonde, 91400 Saclay, France
| | - Tatiana Gorojankina
- Paris-Saclay Institute of Neuroscience, NeuroPSI, CNRS, Paris-Saclay University, Campus CEA Saclay, Bât 151, 151 Route de la Rotonde, 91400 Saclay, France
| | - Sophie Creuzet
- Paris-Saclay Institute of Neuroscience, NeuroPSI, CNRS, Paris-Saclay University, Campus CEA Saclay, Bât 151, 151 Route de la Rotonde, 91400 Saclay, France
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3
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Fasano G, Compagnucci C, Dallapiccola B, Tartaglia M, Lauri A. Teleost Fish and Organoids: Alternative Windows Into the Development of Healthy and Diseased Brains. Front Mol Neurosci 2022; 15:855786. [PMID: 36034498 PMCID: PMC9403253 DOI: 10.3389/fnmol.2022.855786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
The variety in the display of animals’ cognition, emotions, and behaviors, typical of humans, has its roots within the anterior-most part of the brain: the forebrain, giving rise to the neocortex in mammals. Our understanding of cellular and molecular events instructing the development of this domain and its multiple adaptations within the vertebrate lineage has progressed in the last decade. Expanding and detailing the available knowledge on regionalization, progenitors’ behavior and functional sophistication of the forebrain derivatives is also key to generating informative models to improve our characterization of heterogeneous and mechanistically unexplored cortical malformations. Classical and emerging mammalian models are irreplaceable to accurately elucidate mechanisms of stem cells expansion and impairments of cortex development. Nevertheless, alternative systems, allowing a considerable reduction of the burden associated with animal experimentation, are gaining popularity to dissect basic strategies of neural stem cells biology and morphogenesis in health and disease and to speed up preclinical drug testing. Teleost vertebrates such as zebrafish, showing conserved core programs of forebrain development, together with patients-derived in vitro 2D and 3D models, recapitulating more accurately human neurogenesis, are now accepted within translational workflows spanning from genetic analysis to functional investigation. Here, we review the current knowledge of common and divergent mechanisms shaping the forebrain in vertebrates, and causing cortical malformations in humans. We next address the utility, benefits and limitations of whole-brain/organism-based fish models or neuronal ensembles in vitro for translational research to unravel key genes and pathological mechanisms involved in neurodevelopmental diseases.
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4
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Labbaf Z, Petratou K, Ermlich L, Backer W, Tarbashevich K, Reichman-Fried M, Luschnig S, Schulte-Merker S, Raz E. A robust and tunable system for targeted cell ablation in developing embryos. Dev Cell 2022; 57:2026-2040.e5. [PMID: 35914525 DOI: 10.1016/j.devcel.2022.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/10/2022] [Accepted: 07/07/2022] [Indexed: 11/03/2022]
Abstract
Cell ablation is a key method in the research fields of developmental biology, tissue regeneration, and tissue homeostasis. Eliminating specific cell populations allows for characterizing interactions that control cell differentiation, death, behavior, and spatial organization of cells. Current methodologies for inducing cell death suffer from relatively slow kinetics, making them unsuitable for analyzing rapid events and following primary and immediate consequences of the ablation. To address this, we developed a cell-ablation system that is based on bacterial toxin/anti-toxin proteins and enables rapid and cell-autonomous elimination of specific cell types and organs in zebrafish embryos. A unique feature of this system is that it uses an anti-toxin, which allows for controlling the degree and timing of ablation and the resulting phenotypes. The transgenic zebrafish generated in this work represent a highly efficient tool for cell ablation, and this approach is applicable to other model organisms as demonstrated here for Drosophila.
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Affiliation(s)
- Zahra Labbaf
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Kleio Petratou
- Institute for Cardiovascular Organogenesis and Regeneration, Faculty of Medicine, Münster 48149, Germany
| | - Laura Ermlich
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Wilko Backer
- Institute for Integrative Cell Biology and Physiology, University of Münster, Münster 48149, Germany
| | - Katsiaryna Tarbashevich
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Michal Reichman-Fried
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany
| | - Stefan Luschnig
- Institute for Integrative Cell Biology and Physiology, University of Münster, Münster 48149, Germany
| | - Stefan Schulte-Merker
- Institute for Cardiovascular Organogenesis and Regeneration, Faculty of Medicine, Münster 48149, Germany
| | - Erez Raz
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster 48149, Germany.
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5
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Agnès F, Torres-Paz J, Michel P, Rétaux S. A 3D molecular map of the cavefish neural plate illuminates eye-field organization and its borders in vertebrates. Development 2022; 149:274971. [DOI: 10.1242/dev.199966] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 03/18/2022] [Indexed: 01/21/2023]
Abstract
ABSTRACT
The vertebrate retinas originate from a specific anlage in the anterior neural plate called the eye field. Its identity is conferred by a set of ‘eye transcription factors’, whose combinatorial expression has been overlooked. Here, we use the dimorphic teleost Astyanax mexicanus, which develops proper eyes in the wild type and smaller colobomatous eyes in the blind cavefish embryos, to unravel the molecular anatomy of the eye field and its variations within a species. Using a series of markers (rx3, pax6a, cxcr4b, zic1, lhx2, emx3 and nkx2.1a), we draw a comparative 3D expression map at the end of gastrulation/onset of neurulation, which highlights hyper-regionalization of the eye field into sub-territories of distinct sizes, shapes, cell identities and combinatorial gene expression levels along the three body axes. All these features show significant variations in the cavefish natural mutant. We also discover sub-domains within the prospective telencephalon and characterize cell identities at the frontiers of the eye field. We propose putative fates for some of the characterized eye-field subdivisions, and suggest the existence of a trade-off between some subdivisions in the two Astyanax morphs on a micro-evolutionary scale.
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Affiliation(s)
- François Agnès
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
| | - Jorge Torres-Paz
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
| | - Pauline Michel
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
| | - Sylvie Rétaux
- Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, CNRS UMR9197, 91190 Gif-sur-Yvette, France
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6
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Wang YF, Liu C, Xu PF. Deciphering and reconstitution of positional information in the human brain development. ACTA ACUST UNITED AC 2021; 10:29. [PMID: 34467458 PMCID: PMC8408296 DOI: 10.1186/s13619-021-00091-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 08/02/2021] [Indexed: 12/29/2022]
Abstract
Organoid has become a novel in vitro model to research human development and relevant disorders in recent years. With many improvements on the culture protocols, current brain organoids could self-organize into a complicated three-dimensional organization that mimics most of the features of the real human brain at the molecular, cellular, and further physiological level. However, lacking positional information, an important characteristic conveyed by gradients of signaling molecules called morphogens, leads to the deficiency of spatiotemporally regulated cell arrangements and cell–cell interactions in the brain organoid development. In this review, we will overview the role of morphogen both in the vertebrate neural development in vivo as well as the brain organoid culture in vitro, the strategies to apply morphogen concentration gradients in the organoid system and future perspectives of the brain organoid technology.
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Affiliation(s)
- Yi-Fan Wang
- Women's Hospital, and Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Zhejiang University and University of Edinburgh, Jiaxing, Zhejiang, China.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Dr, Singapore, 117599, Singapore
| | - Cong Liu
- Women's Hospital, and Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Peng-Fei Xu
- Women's Hospital, and Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
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7
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Diaz C, Puelles L. Developmental Genes and Malformations in the Hypothalamus. Front Neuroanat 2020; 14:607111. [PMID: 33324176 PMCID: PMC7726113 DOI: 10.3389/fnana.2020.607111] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 10/26/2020] [Indexed: 12/15/2022] Open
Abstract
The hypothalamus is a heterogeneous rostral forebrain region that regulates physiological processes essential for survival, energy metabolism, and reproduction, mainly mediated by the pituitary gland. In the updated prosomeric model, the hypothalamus represents the rostralmost forebrain, composed of two segmental regions (terminal and peduncular hypothalamus), which extend respectively into the non-evaginated preoptic telencephalon and the evaginated pallio-subpallial telencephalon. Complex genetic cascades of transcription factors and signaling molecules rule their development. Alterations of some of these molecular mechanisms acting during forebrain development are associated with more or less severe hypothalamic and pituitary dysfunctions, which may be associated with brain malformations such as holoprosencephaly or septo-optic dysplasia. Studies on transgenic mice with mutated genes encoding critical transcription factors implicated in hypothalamic-pituitary development are contributing to understanding the high clinical complexity of these pathologies. In this review article, we will analyze first the complex molecular genoarchitecture of the hypothalamus resulting from the activity of previous morphogenetic signaling centers and secondly some malformations related to alterations in genes implicated in the development of the hypothalamus.
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Affiliation(s)
- Carmen Diaz
- Department of Medical Sciences, School of Medicine and Institute for Research in Neurological Disabilities, University of Castilla-La Mancha, Albacete, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, University of Murcia, Murcia, Spain
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8
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Korotkova DD, Lyubetsky VA, Ivanova AS, Rubanov LI, Seliverstov AV, Zverkov OA, Martynova NY, Nesterenko AM, Tereshina MB, Peshkin L, Zaraisky AG. Bioinformatics Screening of Genes Specific for Well-Regenerating Vertebrates Reveals c-answer, a Regulator of Brain Development and Regeneration. Cell Rep 2020; 29:1027-1040.e6. [PMID: 31644900 PMCID: PMC6871517 DOI: 10.1016/j.celrep.2019.09.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 01/28/2019] [Accepted: 09/13/2019] [Indexed: 01/28/2023] Open
Abstract
The molecular basis of higher regenerative capacity of cold-blooded animals comparing to warm-blooded ones is poorly understood. Although this difference in regenerative capacities is commonly thought to be a result of restructuring of the same regulatory gene network, we hypothesized that it may be due to loss of some genes essential for regeneration. We describe here a bioinformatic method that allowed us to identify such genes. For investigation in depth we selected one of them encoding transmembrane protein, named “c-Answer.” Using the Xenopus laevis frog as a model cold-blooded animal, we established that c-Answer regulates regeneration of body appendages and telencephalic development through binding to fibroblast growth factor receptors (FGFRs) and P2ry1 receptors and promoting MAPK/ERK and purinergic signaling. This suggests that elimination of c-answer in warm-blooded animals could lead to decreased activity of at least two signaling pathways, which in turn might contribute to changes in mechanisms regulating regeneration and telencephalic development.
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Affiliation(s)
- Daria D Korotkova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCH RAS), 16/10 Miklukho-Maklaya str., Moscow 117997, Russia
| | - Vassily A Lyubetsky
- The Institute for Information Transmission Problems, Russian Academy of Sciences (IITP RAS), 19 Bolshoy Karetny str., Moscow 127051, Russia
| | - Anastasia S Ivanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCH RAS), 16/10 Miklukho-Maklaya str., Moscow 117997, Russia
| | - Lev I Rubanov
- The Institute for Information Transmission Problems, Russian Academy of Sciences (IITP RAS), 19 Bolshoy Karetny str., Moscow 127051, Russia
| | - Alexander V Seliverstov
- The Institute for Information Transmission Problems, Russian Academy of Sciences (IITP RAS), 19 Bolshoy Karetny str., Moscow 127051, Russia
| | - Oleg A Zverkov
- The Institute for Information Transmission Problems, Russian Academy of Sciences (IITP RAS), 19 Bolshoy Karetny str., Moscow 127051, Russia
| | - Natalia Yu Martynova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCH RAS), 16/10 Miklukho-Maklaya str., Moscow 117997, Russia
| | - Alexey M Nesterenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCH RAS), 16/10 Miklukho-Maklaya str., Moscow 117997, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 1/40 Leninskie Gory, Moscow 119991, Russia
| | - Maria B Tereshina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCH RAS), 16/10 Miklukho-Maklaya str., Moscow 117997, Russia
| | - Leonid Peshkin
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrey G Zaraisky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCH RAS), 16/10 Miklukho-Maklaya str., Moscow 117997, Russia.
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9
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Liu B, Satou Y. The genetic program to specify ectodermal cells in ascidian embryos. Dev Growth Differ 2020; 62:301-310. [PMID: 32130723 DOI: 10.1111/dgd.12660] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/11/2020] [Accepted: 02/21/2020] [Indexed: 12/18/2022]
Abstract
The ascidian belongs to the sister group of vertebrates and shares many features with them. The gene regulatory network (GRN) controlling gene expression in ascidian embryonic development leading to the tadpole larva has revealed evolutionarily conserved gene circuits between ascidians and vertebrates. These conserved mechanisms are indeed useful to infer the original developmental programs of the ancestral chordates. Simultaneously, these studies have revealed which gene circuits are missing in the ascidian GRN; these gene circuits may have been acquired in the vertebrate lineage. In particular, the GRN responsible for gene expression in ectodermal cells of ascidian embryos has revealed the genetic programs that regulate the regionalization of the brain, formation of palps derived from placode-like cells, and differentiation of sensory neurons derived from neural crest-like cells. We here discuss how these studies have given insights into the evolution of these traits.
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Affiliation(s)
- Boqi Liu
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Yutaka Satou
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
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10
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Staudt N, Giger FA, Fielding T, Hutt JA, Foucher I, Snowden V, Hellich A, Kiecker C, Houart C. Pineal progenitors originate from a non-neural territory limited by FGF signalling. Development 2019; 146:dev.171405. [PMID: 31754007 PMCID: PMC7375831 DOI: 10.1242/dev.171405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/30/2019] [Indexed: 01/10/2023]
Abstract
The embryonic development of the pineal organ, a neuroendocrine gland on top of the diencephalon, remains enigmatic. Classic fate-mapping studies suggested that pineal progenitors originate from the lateral border of the anterior neural plate. We show here, using gene expression and fate mapping/lineage tracing in zebrafish, that pineal progenitors originate, at least in part, from the non-neural ectoderm. Gene expression in chick indicates that this non-neural origin of pineal progenitors is conserved in amniotes. Genetic repression of placodal, but not neural crest, cell fate results in pineal hypoplasia in zebrafish, while mis-expression of transcription factors known to specify placodal identity during gastrulation promotes the formation of ectopic pineal progenitors. We also demonstrate that fibroblast growth factors (FGFs) position the pineal progenitor domain within the non-neural border by repressing pineal fate and that the Otx transcription factors promote pinealogenesis by inhibiting this FGF activity. The non-neural origin of the pineal organ reveals an underlying similarity in the formation of the pineal and pituitary glands, and suggests that all CNS neuroendocrine organs may require a non-neural contribution to form neurosecretory cells. Highlighted Article: Gene expression and fate mapping/lineage tracing in zebrafish reveals that the pineal organ develops from the non-neural pre-placodal ectoderm under the control of FGF signalling.
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Affiliation(s)
- Nicole Staudt
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Florence A Giger
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Triona Fielding
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - James A Hutt
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Isabelle Foucher
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Vicky Snowden
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Agathe Hellich
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Clemens Kiecker
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
| | - Corinne Houart
- Department for Developmental Neurobiology, Guy's Hospital Campus, King's College London, London SE1 1UL, UK
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11
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Foxg specifies sensory neurons in the anterior neural plate border of the ascidian embryo. Nat Commun 2019; 10:4911. [PMID: 31664020 PMCID: PMC6820760 DOI: 10.1038/s41467-019-12839-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 10/02/2019] [Indexed: 12/12/2022] Open
Abstract
Foxg constitutes a regulatory loop with Fgf8 and plays an important role in the development of anterior placodes and the telencephalon in vertebrate embryos. Ascidians, which belong to Tunicata, the sister group of vertebrates, develop a primitive placode-like structure at the anterior boundary of the neural plate, but lack a clear counterpart of the telencephalon. In this animal, Foxg is expressed in larval palps, which are adhesive organs with sensory neurons. Here, we show that Foxg begins to be expressed in two separate rows of cells within the neural plate boundary region under the control of the MAPK pathway to pattern this region. However, Foxg is not expressed in the brain, and we find no evidence that knockdown of Foxg affects brain formation. Our data suggest that recruitment of Fgf to the downstream of Foxg might have been a critical evolutionary event for the telencephalon in the vertebrate lineage. Vertebrate telencephalon formation requires Foxg-Fgf8 cross-regulation, but while ascidians express Foxg in the neural plate, they lack a telencephalon. Here the authors show that Foxg loss does not affect ascidian brain formation, indicating that telencephalon evolution required recruitment of Fgf downstream of Foxg.
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12
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Abstract
In spite of the high metabolic cost of cellular production, the brain contains only a fraction of the neurons generated during embryonic development. In the rodent cerebral cortex, a first wave of programmed cell death surges at embryonic stages and affects primarily progenitor cells. A second, larger wave unfolds during early postnatal development and ultimately determines the final number of cortical neurons. Programmed cell death in the developing cortex is particularly dependent on neuronal activity and unfolds in a cell-specific manner with precise temporal control. Pyramidal cells and interneurons adjust their numbers in sync, which is likely crucial for the establishment of balanced networks of excitatory and inhibitory neurons. In contrast, several other neuronal populations are almost completely eliminated through apoptosis during the first two weeks of postnatal development, highlighting the importance of programmed cell death in sculpting the mature cerebral cortex.
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Affiliation(s)
- Fong Kuan Wong
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom; .,MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
| | - Oscar Marín
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE1 1UL, United Kingdom; .,MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, United Kingdom
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13
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Prenatal Neuropathologies in Autism Spectrum Disorder and Intellectual Disability: The Gestation of a Comprehensive Zebrafish Model. J Dev Biol 2018; 6:jdb6040029. [PMID: 30513623 PMCID: PMC6316217 DOI: 10.3390/jdb6040029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/20/2018] [Accepted: 11/27/2018] [Indexed: 12/27/2022] Open
Abstract
Autism spectrum disorder (ASD) and intellectual disability (ID) are neurodevelopmental disorders with overlapping diagnostic behaviors and risk factors. These include embryonic exposure to teratogens and mutations in genes that have important functions prenatally. Animal models, including rodents and zebrafish, have been essential in delineating mechanisms of neuropathology and identifying developmental critical periods, when those mechanisms are most sensitive to disruption. This review focuses on how the developmentally accessible zebrafish is contributing to our understanding of prenatal pathologies that set the stage for later ASD-ID behavioral deficits. We discuss the known factors that contribute prenatally to ASD-ID and the recent use of zebrafish to model deficits in brain morphogenesis and circuit development. We conclude by suggesting that a future challenge in zebrafish ASD-ID modeling will be to bridge prenatal anatomical and physiological pathologies to behavioral deficits later in life.
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14
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Alié A, Devos L, Torres-Paz J, Prunier L, Boulet F, Blin M, Elipot Y, Retaux S. Developmental evolution of the forebrain in cavefish, from natural variations in neuropeptides to behavior. eLife 2018; 7:32808. [PMID: 29405116 PMCID: PMC5800845 DOI: 10.7554/elife.32808] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 01/12/2018] [Indexed: 01/11/2023] Open
Abstract
The fish Astyanax mexicanus comes in two forms: the normal surface-dwelling and the blind depigmented cave-adapted morphs. Comparing the development of their basal forebrain, we found quantitative differences in numbers of cells in specific clusters for six out of nine studied neuropeptidergic cell types. Investigating the origins of these differences, we showed that early Shh and Fgf signaling impact on the development of NPY and Hypocretin clusters, via effect on Lhx7 and Lhx9 transcription factors, respectively. Finally, we demonstrated that such neurodevelopmental evolution underlies behavioral evolution, linking a higher number of Hypocretin cells with hyperactivity in cavefish. Early embryonic modifications in signaling/patterning at neural plate stage therefore impact neuronal development and later larval behavior, bridging developmental evolution of a neuronal system and the adaptive behavior it governs. This work uncovers novel variations underlying the evolution and adaptation of cavefish to their extreme environment.
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Affiliation(s)
- Alexandre Alié
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Lucie Devos
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Jorge Torres-Paz
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Lise Prunier
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Fanny Boulet
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Maryline Blin
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Yannick Elipot
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
| | - Sylvie Retaux
- Paris-Saclay Institute of Neuroscience, Université Paris Sud, CNRS UMR9197, Université Paris-Saclay, Avenue de la terrasse, Gif-sur-Yvette, France
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15
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Temporal variations in early developmental decisions: an engine of forebrain evolution. Curr Opin Neurobiol 2017; 42:152-159. [PMID: 28092740 DOI: 10.1016/j.conb.2016.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 11/21/2022]
Abstract
Tight control of developmental timing is pivotal to many major processes in developmental biology, such as patterning, fate specification, cell cycle dynamics, cell migration and connectivity. Temporal change in these ontogenetic sequences is known as heterochrony, a major force in the evolution of body plans and organogenesis. In the last 5 years, studies in fish and rodents indicate that heterochrony in signaling during early development generates diversity in forebrain size and complexity. Here, we summarize these findings and propose that, additionally to spatio-temporal tuning of neurogenesis, temporal and quantitative modulation of signaling events drive pivotal changes in shape, size and complexity of the forebrain across evolution, participating to the generation of diversity in animal behavior and emergence of cognition.
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16
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Sena E, Feistel K, Durand BC. An Evolutionarily Conserved Network Mediates Development of the zona limitans intrathalamica, a Sonic Hedgehog-Secreting Caudal Forebrain Signaling Center. J Dev Biol 2016; 4:jdb4040031. [PMID: 29615594 PMCID: PMC5831802 DOI: 10.3390/jdb4040031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 09/29/2016] [Accepted: 10/13/2016] [Indexed: 12/16/2022] Open
Abstract
Recent studies revealed new insights into the development of a unique caudal forebrain-signaling center: the zona limitans intrathalamica (zli). The zli is the last brain signaling center to form and the first forebrain compartment to be established. It is the only part of the dorsal neural tube expressing the morphogen Sonic Hedgehog (Shh) whose activity participates in the survival, growth and patterning of neuronal progenitor subpopulations within the thalamic complex. Here, we review the gene regulatory network of transcription factors and cis-regulatory elements that underlies formation of a shh-expressing delimitated domain in the anterior brain. We discuss evidence that this network predates the origin of chordates. We highlight the contribution of Shh, Wnt and Notch signaling to zli development and discuss implications for the fact that the morphogen Shh relies on primary cilia for signal transduction. The network that underlies zli development also contributes to thalamus induction, and to its patterning once the zli has been set up. We present an overview of the brain malformations possibly associated with developmental defects in this gene regulatory network (GRN).
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Affiliation(s)
- Elena Sena
- Institut Curie, Université Paris Sud, INSERM U1021, CNRS UMR3347, Centre Universitaire, Bâtiment 110, F-91405 Orsay Cedex, France.
| | - Kerstin Feistel
- Institute of Zoology, University of Hohenheim, Garbenstr. 30, 70593 Stuttgart, Germany.
| | - Béatrice C Durand
- Institut Curie, Université Paris Sud, INSERM U1021, CNRS UMR3347, Centre Universitaire, Bâtiment 110, F-91405 Orsay Cedex, France.
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17
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Fabian P, Pantzartzi CN, Kozmikova I, Kozmik Z. vox homeobox gene: a novel regulator of midbrain-hindbrain boundary development in medaka fish? Dev Genes Evol 2016; 226:99-107. [PMID: 26965282 DOI: 10.1007/s00427-016-0533-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/17/2016] [Indexed: 11/27/2022]
Abstract
The midbrain-hindbrain boundary (MHB) is one of the key organizing centers of the vertebrate central nervous system (CNS). Its patterning is governed by a well-described gene regulatory network (GRN) involving several transcription factors, namely, pax, gbx, en, and otx, together with signaling molecules of the Wnt and Fgf families. Here, we describe the onset of these markers in Oryzias latipes (medaka) early brain development in comparison to previously known zebrafish expression patterns. Moreover, we show for the first time that vox, a member of the vent gene family, is expressed in the developing neural tube similarly to CNS markers. Overexpression of vox leads to profound changes in the gene expression patterns of individual components of MHB-specific GRN, most notably of fgf8, a crucial organizer molecule of MHB. Our data suggest that genes from the vent family, in addition to their crucial role in body axis formation, may play a role in regionalization of vertebrate CNS.
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Affiliation(s)
- Peter Fabian
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, Czech Republic
| | - Chrysoula N Pantzartzi
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, Czech Republic
| | - Iryna Kozmikova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, Czech Republic
| | - Zbynek Kozmik
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4, Czech Republic.
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18
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Abstract
An "organizer" is formally defined as a region, or group of cells in an embryo that can both induce (change the fate) and pattern (generate an organized set of structures) adjacent embryonic cells. To date, about four such regions have been demonstrated: the primary or Spemann organizer (Hensen's node in amniotes), the notochord, the zone of polarizing activity of the limb bud, and the mid-hindbrain boundary. Here we review the evidence for these and compare them with a few other regions which have been proposed to represent other organizers and we speculate on why so few such regions have been discovered.
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Affiliation(s)
- Claire Anderson
- Department of Cell & Developmental Biology, University College London, London, United Kingdom
| | - Claudio D Stern
- Department of Cell & Developmental Biology, University College London, London, United Kingdom.
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19
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Adutwum-Ofosu KK, Magnani D, Theil T, Price DJ, Fotaki V. The molecular and cellular signatures of the mouse eminentia thalami support its role as a signalling centre in the developing forebrain. Brain Struct Funct 2015; 221:3709-27. [PMID: 26459142 PMCID: PMC5009181 DOI: 10.1007/s00429-015-1127-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/30/2015] [Indexed: 12/20/2022]
Abstract
The mammalian eminentia thalami (EmT) (or thalamic eminence) is an embryonic forebrain structure of unknown function. Here, we examined the molecular and cellular properties of the mouse EmT. We first studied mRNA expression of signalling molecules and found that the EmT is a structure, rich in expression of secreted factors, with Wnts being the most abundantly detected. We then examined whether EmT tissue could induce cell fate changes when grafted ectopically. For this, we transplanted EmT tissue from a tau-GFP mouse to the ventral telencephalon of a wild type host, a telencephalic region where Wnt signalling is not normally active but which we showed in culture experiments is competent to respond to Wnts. We observed that the EmT was able to induce in adjacent ventral telencephalic cells ectopic expression of Lef1, a transcriptional activator and a target gene of the Wnt/β-catenin pathway. These Lef1-positive;GFP-negative cells expressed the telencephalic marker Foxg1 but not Ascl1, which is normally expressed by ventral telencephalic cells. These results suggest that the EmT has the capacity to activate Wnt/β-catenin signalling in the ventral telencephalon and to suppress ventral telencephalic gene expression. Altogether, our data support a role of the EmT as a signalling centre in the developing mouse forebrain.
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Affiliation(s)
- Kevin Kofi Adutwum-Ofosu
- The University of Edinburgh, Centre for Integrative Physiology, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Department of Anatomy, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Dario Magnani
- The University of Edinburgh, Centre for Integrative Physiology, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Thomas Theil
- The University of Edinburgh, Centre for Integrative Physiology, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - David J Price
- The University of Edinburgh, Centre for Integrative Physiology, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Vassiliki Fotaki
- The University of Edinburgh, Centre for Integrative Physiology, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.
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20
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La Torre A, Hoshino A, Cavanaugh C, Ware CB, Reh TA. The GIPC1-Akt1 Pathway Is Required for the Specification of the Eye Field in Mouse Embryonic Stem Cells. Stem Cells 2015; 33:2674-85. [PMID: 26013465 DOI: 10.1002/stem.2062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 04/22/2015] [Indexed: 12/20/2022]
Abstract
During early patterning of the neural plate, a single region of the embryonic forebrain, the eye field, becomes competent for eye development. The hallmark of eye field specification is the expression of the eye field transcription factors (EFTFs). Experiments in fish, amphibians, birds, and mammals have demonstrated largely conserved roles for the EFTFs. Although some of the key signaling events that direct the synchronized expression of these factors to the eye field have been elucidated in fish and frogs, it has been more difficult to study these mechanisms in mammalian embryos. In this study, we have used two different methods for directed differentiation of mouse embryonic stem cells (mESCs) to generate eye field cells and retina in vitro to test for a role of the PDZ domain-containing protein GIPC1 in the specification of the mammalian eye primordia. We find that the overexpression of a dominant-negative form of GIPC1 (dnGIPC1), as well as the downregulation of endogenous GIPC1, is sufficient to inhibit the development of eye field cells from mESCs. GIPC1 interacts directly with IGFR and participates in Akt1 activation, and pharmacological inhibition of Akt1 phosphorylation mimics the dnGIPC1 phenotype. Our data, together with previous studies in Xenopus, support the hypothesis that the GIPC1-PI3K-Akt1 pathway plays a key role in eye field specification in vertebrates.
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Affiliation(s)
- Anna La Torre
- Department of Biological Structure, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA.,Department of Cell Biology and Human Anatomy, School of Medicine, University of California, Davis, California, USA
| | - Akina Hoshino
- Department of Biological Structure, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA
| | - Christopher Cavanaugh
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Carol B Ware
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Thomas A Reh
- Department of Biological Structure, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA
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21
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Sánchez-Arrones L, Ferrán JL, Hidalgo-Sanchez M, Puelles L. Origin and early development of the chicken adenohypophysis. Front Neuroanat 2015; 9:7. [PMID: 25741242 PMCID: PMC4330794 DOI: 10.3389/fnana.2015.00007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/12/2015] [Indexed: 01/06/2023] Open
Abstract
The adenohypophysis (ADH) is an important endocrine organ involved in the regulation of many physiological processes. The late morphogenesis of this organ at neural tube stages is well known: the epithelial ADH primordium is recognized as an invagination of the stomodeal roof (Rathke’s pouch), whose walls later thicken and differentiate as the primordium becomes pediculated, and then fully separated from the stomodeum. The primordium attaches to the pial surface of the basal hypothalamus, next to the neurohypophyseal field (NH; future posterior pituitary), from which it was previously separated by migrating prechordal plate (pp) cells. Once the NH evaginates, the ADH surrounds it and jointly forms with it the pituitary gland. In contrast, little is known about the precise origin of the ADH precursors at neural plate stages and how the primordium reaches the stomodeum. For that reason, we produced in the chicken a specific ADH fate map at early neural plate stages, which was amplified with gene markers. By means of experiments labeling the mapped presumptive ADH, we were able to follow the initial anlage into its transformation into Rathke’s pouch. The ADH origin was corroborated to be strictly extraneural, i.e., to lie at stage HH4/5 outside of the anterior neural plate (anp) within the pre-placodal field. The ADH primordium is fully segregated from the anterior neural border cells and the neighboring olfactory placodes both in terms of precursor cells and molecular profile from head fold stages onwards. The placode becomes visible as a molecularly characteristic ectodermal thickening from stage HH10 onwards. The onset of ADH genoarchitectonic regionalization into intermediate and anterior lobes occurs at closed neural tube stages.
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Affiliation(s)
- Luisa Sánchez-Arrones
- Faculty of Medicine, Department of Human Anatomy, School of Medicine and IMIB (Instiuto Murciano de Investigación Biosanitaria), University of Murcia Murcia, Spain
| | - José L Ferrán
- Faculty of Medicine, Department of Human Anatomy, School of Medicine and IMIB (Instiuto Murciano de Investigación Biosanitaria), University of Murcia Murcia, Spain
| | - Matías Hidalgo-Sanchez
- Department of Cell Biology, Faculty of Science, University of Extremadura Badajoz, Spain
| | - Luis Puelles
- Faculty of Medicine, Department of Human Anatomy, School of Medicine and IMIB (Instiuto Murciano de Investigación Biosanitaria), University of Murcia Murcia, Spain
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22
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Jayakody SA, Gonzalez-Cordero A, Ali RR, Pearson RA. Cellular strategies for retinal repair by photoreceptor replacement. Prog Retin Eye Res 2015; 46:31-66. [PMID: 25660226 DOI: 10.1016/j.preteyeres.2015.01.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 01/13/2015] [Accepted: 01/19/2015] [Indexed: 02/08/2023]
Abstract
Loss of photoreceptors due to retinal degeneration is a major cause of blindness in the developed world. While no effective treatment is currently available, cell replacement therapy, using pluripotent stem cell-derived photoreceptor precursor cells, may be a feasible future treatment. Recent reports have demonstrated rescue of visual function following the transplantation of immature photoreceptors and we have seen major advances in our ability to generate transplantation-competent donor cells from stem cell sources. Moreover, we are beginning to realise the possibilities of using endogenous populations of cells from within the retina itself to mediate retinal repair. Here, we present a review of our current understanding of endogenous repair mechanisms together with recent progress in the use of both ocular and pluripotent stem cells for the treatment of photoreceptor loss. We consider how our understanding of retinal development has underpinned many of the recent major advances in translation and moved us closer to the goal of restoring vision by cellular means.
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Affiliation(s)
- Sujatha A Jayakody
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK
| | - Anai Gonzalez-Cordero
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK
| | - Robin R Ali
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK; NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, City Road, London EC1V 2PD, UK
| | - Rachael A Pearson
- Gene and Cell Therapy Group, Department of Genetics, UCL Institute of Ophthalmology, 11-43 Bath St, London EC1V 9EL, UK.
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23
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Juraver-Geslin HA, Durand BC. Early development of the neural plate: new roles for apoptosis and for one of its main effectors caspase-3. Genesis 2015; 53:203-24. [PMID: 25619400 DOI: 10.1002/dvg.22844] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/07/2015] [Indexed: 12/12/2022]
Abstract
Despite its tremendous complexity, the vertebrate nervous system emerges from a homogenous layer of neuroepithelial cells, the neural plate. Its formation relies on the time- and space-controlled progression of developmental programs. Apoptosis is a biological process that removes superfluous and potentially dangerous cells and is implemented through the activation of a molecular pathway conserved during evolution. Apoptosis and an unconventional function of one of its main effectors, caspase-3, contribute to the patterning and growth of the neuroepithelium. Little is known about the intrinsic and extrinsic cues controlling activities of the apoptotic machinery during development. The BarH-like (Barhl) proteins are homeodomain-containing transcription factors. The observations in Caenorhabditis elegans, Xenopus, and mice document that Barhl proteins act in cell survival and as cell type-specific regulators of a caspase-3 function that limits neural progenitor proliferation. In this review, we discuss the roles and regulatory modes of the apoptotic machinery in the development of the neural plate. We focus on the Barhl2, the Sonic Hedgehog, and the Wnt pathways and their activities in neural progenitor survival and proliferation.
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Affiliation(s)
- Hugo A Juraver-Geslin
- Department of Basic Science, Craniofacial Biology, College of Dentistry, New York University, New York, New York
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24
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Cajal M, Creuzet SE, Papanayotou C, Sabéran-Djoneidi D, Chuva de Sousa Lopes SM, Zwijsen A, Collignon J, Camus A. A conserved role for non-neural ectoderm cells in early neural development. Development 2014; 141:4127-38. [DOI: 10.1242/dev.107425] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
During the early steps of head development, ectodermal patterning leads to the emergence of distinct non-neural and neural progenitor cells. The induction of the preplacodal ectoderm and the neural crest depends on well-studied signalling interactions between the non-neural ectoderm fated to become epidermis and the prospective neural plate. By contrast, the involvement of the non-neural ectoderm in the morphogenetic events leading to the development and patterning of the central nervous system has been studied less extensively. Here, we show that the removal of the rostral non-neural ectoderm abutting the prospective neural plate at late gastrulation stage leads, in mouse and chick embryos, to morphological defects in forebrain and craniofacial tissues. In particular, this ablation compromises the development of the telencephalon without affecting that of the diencephalon. Further investigations of ablated mouse embryos established that signalling centres crucial for forebrain regionalization, namely the axial mesendoderm and the anterior neural ridge, form normally. Moreover, changes in cell death or cell proliferation could not explain the specific loss of telencephalic tissue. Finally, we provide evidence that the removal of rostral tissues triggers misregulation of the BMP, WNT and FGF signalling pathways that may affect telencephalon development. This study opens new perspectives on the role of the neural/non-neural interface and reveals its functional relevance across higher vertebrates.
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Affiliation(s)
- Marieke Cajal
- Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, UMR7592 CNRS, Paris F-75013, France
| | - Sophie E. Creuzet
- Institut de Neurobiologie, Laboratoire Neurobiologie et Développement, CNRS-UPR3294, avenue de la Terrasse, Gif-sur-Yvette 91198, France
| | - Costis Papanayotou
- Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, UMR7592 CNRS, Paris F-75013, France
| | - Délara Sabéran-Djoneidi
- Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, UMR7592 CNRS, Paris F-75013, France
| | | | - An Zwijsen
- Laboratory of Developmental Signaling, VIB Center for the Biology of Disease, and KU Leuven, Department for Human Genetics, Leuven 3000, Belgium
| | - Jérôme Collignon
- Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, UMR7592 CNRS, Paris F-75013, France
| | - Anne Camus
- Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, UMR7592 CNRS, Paris F-75013, France
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25
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Aguiar DP, Sghari S, Creuzet S. The facial neural crest controls fore- and midbrain patterning by regulating Foxg1 expression through Smad1 activity. Development 2014; 141:2494-505. [PMID: 24917504 DOI: 10.1242/dev.101790] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The facial neural crest (FNC), a pluripotent embryonic structure forming craniofacial structures, controls the activity of brain organisers and stimulates cerebrum growth. To understand how the FNC conveys its trophic effect, we have studied the role of Smad1, which encodes an intracellular transducer, to which multiple signalling pathways converge, in the regulation of Foxg1. Foxg1 is a transcription factor essential for telencephalic specification, the mutation of which leads to microcephaly and mental retardation. Smad1 silencing, based on RNA interference (RNAi), was performed in pre-migratory FNC cells. Soon after electroporation of RNAi molecules, Smad1 inactivation abolished the expression of Foxg1 in the chick telencephalon, resulting in dramatic microcephaly and partial holoprosencephaly. In addition, the depletion of Foxg1 activity altered the expression Otx2 and Foxa2 in di/mesencephalic neuroepithelium. However, when mutated forms of Smad1 mediating Fgf and Wnt signalling were transfected into FNC cells, these defects were overcome. We also show that, downstream of Smad1 activity, Dkk1, a Wnt antagonist produced by the FNC, initiated the specification of the telencephalon by regulating Foxg1 activity. Additionally, the activity of Cerberus in FNC-derived mesenchyme synergised with Dkk1 to control Foxg1 expression and maintain the balance between Otx2 and Foxa2.
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Affiliation(s)
- Diego P Aguiar
- Institut de Neurobiologie, Laboratoire de Neurobiologie et Développement, Avenue de la Terrasse, Gif-sur-Yvette 91198, France
| | - Soufien Sghari
- Institut de Neurobiologie, Laboratoire de Neurobiologie et Développement, Avenue de la Terrasse, Gif-sur-Yvette 91198, France
| | - Sophie Creuzet
- Institut de Neurobiologie, Laboratoire de Neurobiologie et Développement, Avenue de la Terrasse, Gif-sur-Yvette 91198, France
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26
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Tereshina MB, Ermakova GV, Ivanova AS, Zaraisky AG. Ras-dva1 small GTPase regulates telencephalon development in Xenopus laevis embryos by controlling Fgf8 and Agr signaling at the anterior border of the neural plate. Biol Open 2014; 3:192-203. [PMID: 24570397 PMCID: PMC4001240 DOI: 10.1242/bio.20147401] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We previously found that the small GTPase Ras-dva1 is essential for the telencephalic development in Xenopus laevis because Ras-dva1 controls the Fgf8-mediated induction of FoxG1 expression, a key telencephalic regulator. In this report, we show, however, that Ras-dva1 and FoxG1 are expressed in different groups of cells; whereas Ras-dva1 is expressed in the outer layer of the anterior neural fold, FoxG1 and Fgf8 are activated in the inner layer from which the telencephalon is derived. We resolve this paradox by demonstrating that Ras-dva1 is involved in the transduction of Fgf8 signal received by cells in the outer layer, which in turn send a feedback signal that stimulates FoxG1 expression in the inner layer. We show that this feedback signal is transmitted by secreted Agr proteins, the expression of which is activated in the outer layer by mediation of Ras-dva1 and the homeodomain transcription factor Otx2. In turn, Agrs are essential for maintaining Fgf8 and FoxG1 expression in cells at the anterior neural plate border. Our finding reveals a novel feedback loop mechanism based on the exchange of Fgf8 and Agr signaling between neural and non-neural compartments at the anterior margin of the neural plate and demonstrates a key role of Ras-dva1 in this mechanism.
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Affiliation(s)
- Maria B Tereshina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
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27
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Cavodeassi F. Integration of anterior neural plate patterning and morphogenesis by the Wnt signaling pathway. Dev Neurobiol 2013; 74:759-71. [PMID: 24115566 DOI: 10.1002/dneu.22135] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 09/13/2013] [Accepted: 09/23/2013] [Indexed: 01/08/2023]
Abstract
Wnts are essential for a multitude of processes during embryonic development and adult homeostasis. The molecular structure of the Wnt pathway is extremely complex, and it keeps growing as new molecular components and novel interactions are uncovered. Recent studies have advanced our understanding on how the diverse molecular outcomes of the Wnt pathway are integrated during organ development, an integration that is also essential, although mechanistically poorly understood, during the formation of the anterior part of the nervous system, the forebrain. In this article, the author has summarized these findings and discussed their implications for forebrain development. A special emphasis has been put forth on studies performed in the zebrafish as this model system has been instrumental for our current understanding of forebrain patterning.
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Affiliation(s)
- Florencia Cavodeassi
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Nicolás Cabrera 1, 28049, Madrid, Spain
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28
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Annenkov A. Receptor tyrosine kinase (RTK) signalling in the control of neural stem and progenitor cell (NSPC) development. Mol Neurobiol 2013; 49:440-71. [PMID: 23982746 DOI: 10.1007/s12035-013-8532-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 08/09/2013] [Indexed: 01/04/2023]
Abstract
Important developmental responses are elicited in neural stem and progenitor cells (NSPC) by activation of the receptor tyrosine kinases (RTK), including the fibroblast growth factor receptors, epidermal growth factor receptor, platelet-derived growth factor receptors and insulin-like growth factor receptor (IGF1R). Signalling through these RTK is necessary and sufficient for driving a number of developmental processes in the central nervous system. Within each of the four RTK families discussed here, receptors are activated by sets of ligands that do not cross-activate receptors of the other three families, and therefore, their activation can be independently regulated by ligand availability. These RTK pathways converge on a conserved core of signalling molecules, but differences between the receptors in utilisation of signalling molecules and molecular adaptors for intracellular signal propagation become increasingly apparent. Intracellular inhibitors of RTK signalling are widely involved in the regulation of developmental signalling in NSPC and often determine developmental outcomes of RTK activation. In addition, cellular responses of NSPC to the activation of a given RTK may be significantly modulated by signal strength. Cellular propensity to respond also plays a role in developmental outcomes of RTK signalling. In combination, these mechanisms regulate the balance between NSPC maintenance and differentiation during development and in adulthood. Attribution of particular developmental responses of NSPC to specific pathways of RTK signalling becomes increasingly elucidated. Co-activation of several RTK in developing NSPC is common, and analysis of co-operation between their signalling pathways may advance knowledge of RTK role in NSPC development.
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Affiliation(s)
- Alexander Annenkov
- Bone and Joint Research Unit, William Harvey Research Institute, Bart's and The London School of Medicine, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK,
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29
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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: 207] [Impact Index Per Article: 18.8] [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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30
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Andoniadou CL, Martinez-Barbera JP. Developmental mechanisms directing early anterior forebrain specification in vertebrates. Cell Mol Life Sci 2013; 70:3739-52. [PMID: 23397132 PMCID: PMC3781296 DOI: 10.1007/s00018-013-1269-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 01/10/2013] [Accepted: 01/17/2013] [Indexed: 12/14/2022]
Abstract
Research from the last 15 years has provided a working model for how the anterior forebrain is induced and specified during the early stages of embryogenesis. This model relies on three basic processes: (1) induction of the neural plate from naive ectoderm requires the inhibition of BMP/TGFβ signaling; (2) induced neural tissue initially acquires an anterior identity (i.e., anterior forebrain); (3) maintenance and expansion of the anterior forebrain depends on the antagonism of posteriorizing signals that would otherwise transform this tissue into posterior neural fates. In this review, we present a historical perspective examining some of the significant experiments that have helped to delineate this molecular model. In addition, we discuss the function of the relevant tissues that act prior to and during gastrulation to ensure proper anterior forebrain formation. Finally, we elaborate data, mainly obtained from the analyses of mouse mutants, supporting a role for transcriptional repressors in the regulation of cell competence within the anterior forebrain. The aim of this review is to provide the reader with a general overview of the signals as well as the signaling centers that control the development of the anterior neural plate.
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Affiliation(s)
- Cynthia Lilian Andoniadou
- Birth Defects Research Centre, UCL Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
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31
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Bielen H, Houart C. BMP signaling protects telencephalic fate by repressing eye identity and its Cxcr4-dependent morphogenesis. Dev Cell 2013; 23:812-22. [PMID: 23079599 DOI: 10.1016/j.devcel.2012.09.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 08/08/2012] [Accepted: 09/07/2012] [Indexed: 12/22/2022]
Abstract
Depletion of Wnt signaling is a major requirement for the induction of the anterior prosencephalon. However, the molecular events driving the differential regionalization of this area into eye-field and telencephalon fates are still unknown. Here we show that the BMP pathway is active in the anterior neural ectoderm during late blastula to early gastrula stage in zebrafish. Bmp2b mutants and mosaic loss-of-function experiments reveal that BMP acts as a repressor of eye-field fate through inhibition of its key transcription factor Rx3, thereby protecting the future telencephalon from acquiring eye identity. This BMP-driven mechanism initiates the establishment of the telencephalon prior to the involvement of Wnt antagonists from the anterior neural border. Furthermore, we demonstrate that Rx3 and BMP are respectively required to maintain and restrict the chemokine receptor cxcr4a, which in turn contributes to the morphogenetic separation of eye-field and telencephalic cells during early neurulation.
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Affiliation(s)
- Holger Bielen
- Medical Research Council Centre for Developmental Neurobiology, King's College London, London SE1 1UL, UK
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32
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Beccari L, Marco-Ferreres R, Bovolenta P. The logic of gene regulatory networks in early vertebrate forebrain patterning. Mech Dev 2012; 130:95-111. [PMID: 23111324 DOI: 10.1016/j.mod.2012.10.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 10/09/2012] [Indexed: 01/19/2023]
Abstract
The vertebrate forebrain or prosencephalon is patterned at the beginning of neurulation into four major domains: the telencephalic, hypothalamic, retinal and diencephalic anlagen. These domains will then give rise to the majority of the brain structures involved in sensory integration and the control of higher intellectual and homeostatic functions. Understanding how forebrain pattering arises has thus attracted the interest of developmental neurobiologists for decades. As a result, most of its regulators have been identified and their hierarchical relationship is now the object of active investigation. Here, we summarize the main morphogenetic pathways and transcription factors involved in forebrain specification and propose the backbone of a possible gene regulatory network (GRN) governing its specification, taking advantage of the GRN principles elaborated by pioneer studies in simpler organisms. We will also discuss this GRN and its operational logic in the context of the remarkable morphological and functional diversification that the forebrain has undergone during evolution.
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Affiliation(s)
- Leonardo Beccari
- Centro de Biología Molecular "Severo Ochoa", CSIC-UAM, c/Nicolas Cabrera, 1, Madrid 28049, Spain
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33
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Le Douarin NM, Dupin E. The neural crest in vertebrate evolution. Curr Opin Genet Dev 2012; 22:381-9. [DOI: 10.1016/j.gde.2012.06.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 06/11/2012] [Accepted: 06/12/2012] [Indexed: 01/10/2023]
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34
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Danesin C, Houart C. A Fox stops the Wnt: implications for forebrain development and diseases. Curr Opin Genet Dev 2012; 22:323-30. [DOI: 10.1016/j.gde.2012.05.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 04/17/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022]
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35
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Affiliation(s)
- Clemens Kiecker
- Medical Research Council (MRC) Center for Developmental Neurobiology, King's College, London SE1 1UL, United Kingdom; ,
| | - Andrew Lumsden
- Medical Research Council (MRC) Center for Developmental Neurobiology, King's College, London SE1 1UL, United Kingdom; ,
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36
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Robertshaw E, Kiecker C. Phylogenetic origins of brain organisers. SCIENTIFICA 2012; 2012:475017. [PMID: 24278699 PMCID: PMC3820451 DOI: 10.6064/2012/475017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 06/21/2012] [Indexed: 06/02/2023]
Abstract
The regionalisation of the nervous system begins early in embryogenesis, concomitant with the establishment of the anteroposterior (AP) and dorsoventral (DV) body axes. The molecular mechanisms that drive axis induction appear to be conserved throughout the animal kingdom and may be phylogenetically older than the emergence of bilateral symmetry. As a result of this process, groups of patterning genes that are equally well conserved are expressed at specific AP and DV coordinates of the embryo. In the emerging nervous system of vertebrate embryos, this initial pattern is refined by local signalling centres, secondary organisers, that regulate patterning, proliferation, and axonal pathfinding in adjacent neuroepithelium. The main secondary organisers for the AP neuraxis are the midbrain-hindbrain boundary, zona limitans intrathalamica, and anterior neural ridge and for the DV neuraxis the notochord, floor plate, and roof plate. A search for homologous secondary organisers in nonvertebrate lineages has led to controversy over their phylogenetic origins. Based on a recent study in hemichordates, it has been suggested that the AP secondary organisers evolved at the base of the deuterostome superphylum, earlier than previously thought. According to this view, the lack of signalling centres in some deuterostome lineages is likely to reflect a secondary loss due to adaptive processes. We propose that the relative evolutionary flexibility of secondary organisers has contributed to a broader morphological complexity of nervous systems in different clades.
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Affiliation(s)
- Ellen Robertshaw
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunt's House, Guy's Hospital Campus, London SE1 1UL, UK
| | - Clemens Kiecker
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor, New Hunt's House, Guy's Hospital Campus, London SE1 1UL, UK
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37
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Le Douarin NM, Couly G, Creuzet SE. The neural crest is a powerful regulator of pre-otic brain development. Dev Biol 2012; 366:74-82. [DOI: 10.1016/j.ydbio.2012.01.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 01/10/2012] [Indexed: 11/27/2022]
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38
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Martinez-Ferre A, Martinez S. Molecular regionalization of the diencephalon. Front Neurosci 2012; 6:73. [PMID: 22654731 PMCID: PMC3360461 DOI: 10.3389/fnins.2012.00073] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 05/03/2012] [Indexed: 01/29/2023] Open
Abstract
The anatomic complexity of the diencephalon depends on precise molecular and cellular regulative mechanisms orchestrated by regional morphogenetic organizers at the neural tube stage. In the diencephalon, like in other neural tube regions, dorsal and ventral signals codify positional information to specify ventro-dorsal regionalization. Retinoic acid, Fgf8, BMPs, and Wnts signals are the molecular factors acting upon the diencephalic epithelium to specify dorsal structures, while Shh is the main ventralizing signal. A central diencephalic organizer, the zona limitans intrathalamica (ZLI), appears after neurulation in the central diencephalic alar plate, establishing additional antero-posterior positional information inside diencephalic alar plate. Based on Shh expression, the ZLI acts as a morphogenetic center, which cooperates with other signals in thalamic specification and pattering in the alar plate of diencephalon. Indeed, Shh is expressed first in the basal plate extending dorsally through the ZLI epithelium as the development proceeds. Despite the importance of ZLI in diencephalic morphogenesis the mechanisms that regulate its development remain incompletely understood. Actually, controversial interpretations in different experimental models have been proposed. That is, experimental results have suggested that (i) the juxtaposition of the molecularly heterogeneous neuroepithelial areas, (ii) cell reorganization in the epithelium, and/or (iii) planar and vertical inductions in the neural epithelium, are required for ZLI specification and development. We will review some experimental data to approach the study of the molecular regulation of diencephalic regionalization, with special interest in the cellular mechanisms underlying planar inductions.
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39
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Sanchez-Arrones L, Stern CD, Bovolenta P, Puelles L. Sharpening of the anterior neural border in the chick by rostral endoderm signalling. Development 2012; 139:1034-44. [PMID: 22318633 DOI: 10.1242/dev.067934] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The anterior border of the neural plate, presumed to contain the prospective peripheral portion (roof) of the prospective telencephalon, emerges within a vaguely defined proneural ectodermal region. Fate maps carried out at HH4 in the chick reveal that this region still produces indistinctly neural, placodal and non-neural derivatives; it does not express neural markers. We examined how the definitive anterior border domain of the rostral forebrain becomes established and comes to display a neural molecular profile, whereas local non-neural derivatives become separated. The process, interpreted as a border sharpening mechanism via intercalatory cell movements, was studied using fate mapping, time-lapse microscopy and in situ hybridization. Separation of neural and non-neural domains proceeds along stages HH4-HH4+, is well advanced at HH5, and is accompanied by a novel dorsoventral intercalation, oriented orthogonal to the border, that distributes transitional cells into molecularly distinct neural and non-neural fields. Meanwhile, neuroectodermal Sox2 expression spreads peripherally from the neighbourhood of the node, reaching the nascent anterior border domain at HH5. We also show that concurrent signals from the endodermal layer are necessary to position and sharpen the neural border, and suggest that FGF8 might be a component of this signalling.
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Affiliation(s)
- Luisa Sanchez-Arrones
- Department of Human Anatomy and Psychobiology, University of Murcia, School of Medicine, Murcia, Spain.
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40
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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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41
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Cajal M, Lawson KA, Hill B, Moreau A, Rao J, Ross A, Collignon J, Camus A. Clonal and molecular analysis of the prospective anterior neural boundary in the mouse embryo. Development 2012; 139:423-36. [PMID: 22186731 DOI: 10.1242/dev.075499] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In the mouse embryo the anterior ectoderm undergoes extensive growth and morphogenesis to form the forebrain and cephalic non-neural ectoderm. We traced descendants of single ectoderm cells to study cell fate choice and cell behaviour at late gastrulation. In addition, we provide a comprehensive spatiotemporal atlas of anterior gene expression at stages crucial for anterior ectoderm regionalisation and neural plate formation. Our results show that, at late gastrulation stage, expression patterns of anterior ectoderm genes overlap significantly and correlate with areas of distinct prospective fates but do not define lineages. The fate map delineates a rostral limit to forebrain contribution. However, no early subdivision of the presumptive forebrain territory can be detected. Lineage analysis at single-cell resolution revealed that precursors of the anterior neural ridge (ANR), a signalling centre involved in forebrain development and patterning, are clonally related to neural ectoderm. The prospective ANR and the forebrain neuroectoderm arise from cells scattered within the same broad area of anterior ectoderm. This study establishes that although the segregation between non-neural and neural precursors in the anterior midline ectoderm is not complete at late gastrulation stage, this tissue already harbours elements of regionalisation that prefigure the later organisation of the head.
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Affiliation(s)
- Marieke Cajal
- Université Paris Diderot, Sorbonne Paris Cité, Institut Jacques Monod, UMR7592 CNRS, F-75013 Paris, France
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42
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de Lussanet MH, Osse JW. An ancestral axial twist explains the contralateral forebrain and the optic chiasm in vertebrates. ANIM BIOL 2012. [DOI: 10.1163/157075611x617102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Among the best-known facts of the brain are the contralateral visual, auditory, sensational, and motor mappings in the forebrain. How and why did these evolve? The few theories to this question provide functional answers, such as better networks for visuomotor control. However, these theories contradict the data, as discussed here. Instead we propose that a 90-deg turn on the left side evolved in a common ancestor of all vertebrates. Compensatory migrations of the tissues during development restore body symmetry. Eyes, nostrils and forebrain compensate in the direction of the turn, whereas more caudal structures migrate in the opposite direction. As a result of these opposite migrations the forebrain becomes crossed and inverted with respect to the rest of the nervous system. We show that such compensatory migratory movements can indeed be observed in the zebrafish (Danio rerio) and the chick (Gallus gallus). With a model we show how the axial twist hypothesis predicts that an optic chiasm should develop on the ventral side of the brain, whereas the olfactory tract should be uncrossed. In addition, the hypothesis explains the decussation of the trochlear nerve, why olfaction is non-crossed, why the cerebellar hemispheres represent the ipsilateral bodyside, why in sharks the forebrain halves each represent the ipsilateral eye, why the heart and other inner organs are asymmetric in the body. Due to the poor fossil record, the possible evolutionary scenarios remain speculative. Molecular evidence does support the hypothesis. The findings may shed new insight on the problematic structure of the forebrain.
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Affiliation(s)
- Marc H.E. de Lussanet
- Institute of Psychology, Westf. Wilhelms-Universität, Fliednerstraße 21, 48149 Münster, Germany
| | - Jan W.M. Osse
- Bennekomseweg 83, 6704 AH Wageningen, The Netherlands
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43
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Paek H, Hwang JY, Zukin RS, Hébert JM. β-Catenin-dependent FGF signaling sustains cell survival in the anterior embryonic head by countering Smad4. Dev Cell 2011; 20:689-99. [PMID: 21571225 DOI: 10.1016/j.devcel.2011.04.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 03/02/2011] [Accepted: 04/26/2011] [Indexed: 12/22/2022]
Abstract
Growing evidence suggests that FGFs secreted from embryonic signaling centers are key mediators of cell survival. However, the mechanisms regulating FGF-dependent cell survival remain obscure. At the rostral end of the embryo, for example, ablation of FGF signaling leads to the rapid death of the precursor cells that form the anterior head, including the telencephalon. Here, we outline a core genetic circuit that regulates survival in the embryonic mouse head: WNT signaling through β-catenin directly maintains FGF expression and requires FGF function in vivo to oppose proapoptotic TGF-β signaling through SMAD4. Moreover, these antagonistic pathways converge on the transcriptional regulation of apoptosis, and genes such as Cdkn1a, suggesting a mechanism for how signaling centers in the embryonic head regulate cell survival.
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Affiliation(s)
- Hunki Paek
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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44
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Causeret F, Ensini M, Teissier A, Kessaris N, Richardson WD, Lucas de Couville T, Pierani A. Dbx1-expressing cells are necessary for the survival of the mammalian anterior neural and craniofacial structures. PLoS One 2011; 6:e19367. [PMID: 21552538 PMCID: PMC3084286 DOI: 10.1371/journal.pone.0019367] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 04/04/2011] [Indexed: 01/12/2023] Open
Abstract
Development of the vertebrate forebrain and craniofacial structures are intimately linked processes, the coordinated growth of these tissues being required to ensure normal head formation. In this study, we identify five small subsets of progenitors expressing the transcription factor dbx1 in the cephalic region of developing mouse embryos at E8.5. Using genetic tracing we show that dbx1-expressing cells and their progeny have a modest contribution to the forebrain and face tissues. However, their genetic ablation triggers extensive and non cell-autonomous apoptosis as well as a decrease in proliferation in surrounding tissues, resulting in the progressive loss of most of the forebrain and frontonasal structures. Targeted ablation of the different subsets reveals that the very first dbx1-expressing progenitors are critically required for the survival of anterior neural tissues, the production and/or migration of cephalic neural crest cells and, ultimately, forebrain formation. In addition, we find that the other subsets, generated at slightly later stages, each play a specific function during head development and that their coordinated activity is required for accurate craniofacial morphogenesis. Our results demonstrate that dbx1-expressing cells have a unique function during head development, notably by controlling cell survival in a non cell-autonomous manner.
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Affiliation(s)
- Frédéric Causeret
- CNRS UMR 7592, Institut Jacques Monod, Univ Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Monica Ensini
- CNRS UMR 7592, Institut Jacques Monod, Univ Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Anne Teissier
- CNRS UMR 7592, Institut Jacques Monod, Univ Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Nicoletta Kessaris
- Department of Cell and Developmental Biology and Wolfson Institute for Biomedical Research, University College London, London, United Kingdom
| | - William D. Richardson
- Department of Cell and Developmental Biology and Wolfson Institute for Biomedical Research, University College London, London, United Kingdom
| | | | - Alessandra Pierani
- CNRS UMR 7592, Institut Jacques Monod, Univ Paris Diderot, Sorbonne Paris Cité, Paris, France
- * E-mail:
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45
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Burroughs-Garcia J, Sittaramane V, Chandrasekhar A, Waters ST. Evolutionarily conserved function of Gbx2 in anterior hindbrain development. Dev Dyn 2011; 240:828-38. [PMID: 21360792 DOI: 10.1002/dvdy.22589] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2011] [Indexed: 11/08/2022] Open
Abstract
The amino acid sequence across the DNA-binding homeodomain of Gbx2 is highly conserved across multiple species. In mice, Gbx2 is essential for establishment of the midbrain-hindbrain boundary (MHB), and in development of anterior hindbrain structures, rhombomeres (r) 1-r3, and the r2/r3-derived cranial nerve V. In contrast, studies in zebrafish have implicated gbx1 in establishment of the MHB. Therefore, we tested potential roles for gbx2 in anterior hindbrain development in zebrafish. gbx2 knockdown with antisense morpholino results in increased cell death in r2, r3, and r5 and a truncation of the anterior hindbrain, similar to the defect in Gbx2(-/-) mice. Moreover, there is abnormal clustering of cranial nerve V cell bodies in r2 and r3 indicative of defects in aspects of anterior hindbrain patterning. These phenotypes can be rescued by expression of the mouse GBX2 protein. These results suggest that gbx2/Gbx2 has an evolutionarily conserved role in anterior hindbrain development.
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Affiliation(s)
- Jessica Burroughs-Garcia
- Division of Biological Sciences and Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
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46
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Abstract
The myelin sheath is an essential component of the vertebrate nervous system, and its disruption causes numerous diseases, including multiple sclerosis (MS), and neurodegeneration. Although we understand a great deal about the early development of the glial cells that make myelin (Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system), we know much less about the cellular and molecular mechanisms that regulate the later stages of differentiation that orchestrate myelin formation. Over the past decade, the zebrafish has been employed as a model with which to dissect the development of myelinated axons. Forward genetic screens have revealed new genes essential for myelination, as well as new roles for genes previously implicated in myelinated axon formation in other systems. High-resolution in vivo imaging in zebrafish has also begun to illuminate novel cell behaviors during myelinating glial cell development. Here we review the contribution of zebrafish research to our understanding of myelinated axon formation to date. We also describe and discuss many of the methodologies used in these studies and preview future endeavors that will ensure that the zebrafish remains at the cutting edge of this important area of research.
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Affiliation(s)
- Tim Czopka
- Centre for Neuroregeneration, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, UK
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47
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Ota S, Tonou-Fujimori N, Tonou-Fujimori N, Nakayama Y, Ito Y, Kawamura A, Yamasu K. FGF receptor gene expression and its regulation by FGF signaling during early zebrafish development. Genesis 2010; 48:707-16. [PMID: 20960516 DOI: 10.1002/dvg.20682] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 09/11/2010] [Accepted: 10/07/2010] [Indexed: 12/23/2022]
Abstract
The expression of all four fgfr genes was extensively examined throughout early embryogenesis of the zebrafish (Danio rerio). fgfr1 alone was expressed maternally throughout the blastoderm, and then zygotically in the anterior neural plate and presomitic mesoderm. fgfr4 expression was first detected in late blastulae and was gradually restricted to the brain. fgfr2 and fgfr3 expression were initiated in early and late gastrulae, respectively; fgfr2 was expressed in the anterior neural plate and somitic mesoderm, whereas fgfr3 was activated in the axial mesoderm and then in the midbrain and somitic mesoderm. During somitogenesis, each of these fgfr genes was expressed in a characteristic manner in the brain. Using an FGF signal inhibitor, dominant-negative FGF receptors and fgf8.1/fgf8a mutants, we found that fgfr expression is directly or indirectly regulated by FGF signaling during epiboly and at the end of somitogenesis, revealing the presence of an autoregulatory mechanism.
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Affiliation(s)
- Satoshi Ota
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Shimo-Okubo, Sakura-ku, Saitama, Japan
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48
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49
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Viktorin G, Chiuchitu C, Rissler M, Varga ZM, Westerfield M. Emx3 is required for the differentiation of dorsal telencephalic neurons. Dev Dyn 2009; 238:1984-98. [PMID: 19650145 DOI: 10.1002/dvdy.22031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
emx3 is first expressed in prospective telencephalic cells at the anterior border of the zebrafish neural plate. Knockdown of Emx3 function by morpholino reduces the expression of markers specific to dorsal telencephalon, and impairs axon tract formation. Rescue of both early and late markers requires low-level expression of emx3 at the one- or two-somite stage. Higher emx3 expression levels cause dorsal telencephalic markers to expand ventrally, which points to a possible role of emx3 in specifying dorsal telencephalon and a potential new function for Wnt/beta-catenin pathway activation. In contrast to mice, where Emx2 plays a major role in dorsal telencephalic development, knockdown of zebrafish Emx2 apparently does not affect telencephalic development. Similarly, Emx1 knockdown has little effect. Previously, emx3 was thought to be fish-specific. However, we found all three emx orthologs in Xenopus tropicalis and opossum (Monodelphis domestica) genomes, indicating that emx3 was present in an ancestral tetrapod genome.
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Affiliation(s)
- Gudrun Viktorin
- Institute of Developmental Biology, University of Freiburg, Freiburg, Germany
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50
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Paek H, Gutin G, Hébert JM. FGF signaling is strictly required to maintain early telencephalic precursor cell survival. Development 2009; 136:2457-65. [PMID: 19542358 DOI: 10.1242/dev.032656] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The FGF family of extracellular signaling factors has been proposed to play multiple roles in patterning the telencephalon, the precursor to the cerebrum. In this study, unlike previous ones, we effectively abolish FGF signaling in the anterior neural plate via deletion of three FGF receptor (FGFR) genes. Triple FGFR mutant mice exhibit a complete loss of the telencephalon, except the dorsal midline. Disruption of FGF signaling prior to and coincident with telencephalic induction reveals that FGFs promote telencephalic character and are strictly required to keep telencephalic cells alive. Moreover, progressively more severe truncations of the telencephalon are observed in FGFR single, double and triple mutants. Together with previous gain-of-function studies showing induction of Foxg1 expression and mirror-image duplications of the cortex by exogenous FGF8, our loss-of-function results suggest that, rather than independently patterning different areas, FGF ligands and receptors act in concert to mediate organizer activity for the whole telencephalon.
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Affiliation(s)
- Hunki Paek
- Departments of Neuroscience and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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