1
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Manning E, Placzek M. Organizing activities of axial mesoderm. Curr Top Dev Biol 2024; 157:83-123. [PMID: 38556460 DOI: 10.1016/bs.ctdb.2024.02.007] [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
For almost a century, developmental biologists have appreciated that the ability of the embryonic organizer to induce and pattern the body plan is intertwined with its differentiation into axial mesoderm. Despite this, we still have a relatively poor understanding of the contribution of axial mesoderm to induction and patterning of different body regions, and the manner in which axial mesoderm-derived information is interpreted in tissues of changing competence. Here, with a particular focus on the nervous system, we review the evidence that axial mesoderm notochord and prechordal mesoderm/mesendoderm act as organizers, discuss how their influence extends through the different axes of the developing organism, and describe how the ability of axial mesoderm to direct morphogenesis impacts on its role as a local organizer.
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Affiliation(s)
- Elizabeth Manning
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom; Bateson Centre, University of Sheffield, Sheffield, United Kingdom
| | - Marysia Placzek
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom; Bateson Centre, University of Sheffield, Sheffield, United Kingdom; Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom.
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2
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Abstract
In avian and mammalian embryos the "organizer" property associated with neural induction of competent ectoderm into a neural plate and its subsequent patterning into rostro-caudal domains resides at the tip of the primitive streak before neurulation begins, and before a morphological Hensen's node is discernible. The same region and its later derivatives (like the notochord) also have the ability to "dorsalize" the adjacent mesoderm, for example by converting lateral plate mesoderm into paraxial (pre-somitic) mesoderm. Both neural induction and dorsalization of the mesoderm involve inhibition of BMP, and the former also requires other signals. This review surveys the key experiments done to elucidate the functions of the organizer and the mechanisms of neural induction in amniotes. We conclude that the mechanisms of neural induction in amniotes and anamniotes are likely to be largely the same; apparent differences are likely to be due to differences in experimental approaches dictated by embryo topology and other practical constraints. We also discuss the relationships between "neural induction" assessed by grafts of the organizer and normal neural plate development, as well as how neural induction relates to the generation of neuronal cells from embryonic and other stem cells in vitro.
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Affiliation(s)
- Claudio D Stern
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.
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3
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Ferran JL, Irimia M, Puelles L. Is There a Prechordal Region and an Acroterminal Domain in Amphioxus? BRAIN, BEHAVIOR AND EVOLUTION 2022; 96:334-352. [PMID: 35034027 DOI: 10.1159/000521966] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/03/2022] [Indexed: 12/16/2022]
Abstract
This essay re-examines the singular case of the supposedly unique rostrally elongated notochord described classically in amphioxus. We start from our previous observations in hpf 21 larvae [Albuixech-Crespo et al.: PLoS Biol. 2017;15(4):e2001573] indicating that the brain vesicle has rostrally a rather standard hypothalamic molecular configuration. This correlates with the notochord across a possible rostromedian acroterminal hypothalamic domain. The notochord shows some molecular differences that specifically characterize its pre-acroterminal extension beyond its normal rostral end under the mamillary region. We explored an alternative interpretation that the putative extension of this notochord actually represents a variant form of the prechordal plate in amphioxus, some of whose cells would adopt the notochordal typology, but would lack notochordal patterning properties, and might have some (but not all) prechordal ones instead. We survey in detail the classic and recent literature on gastrulation, prechordal plate, and notochord formation in amphioxus, compare the observed patterns with those of some other vertebrates of interest, and re-examine the literature on differential gene expression patterns in this rostralmost area of the head. We noted that previous literature failed to identify the amphioxus prechordal primordia at appropriate stages. Under this interpretation, a consistent picture can be drawn for cephalochordates, tunicates, and vertebrates. Moreover, there is little evidence for an intrinsic capacity of the early notochord to grow rostralwards (it normally elongates caudalwards). Altogether, we conclude that the hypothesis of a prechordal nature of the elongated amphioxus notochord is consistent with the evidence presented.
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Affiliation(s)
- José Luis Ferran
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia - IMIB, Virgen de la Arrixaca University Hospital, Murcia, Spain
| | - Manuel Irimia
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain.,ICREA, Barcelona, Spain
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia, Murcia, Spain.,Institute of Biomedical Research of Murcia - IMIB, Virgen de la Arrixaca University Hospital, Murcia, Spain
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4
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Yoshihi K, Kato K, Iida H, Teramoto M, Kawamura A, Watanabe Y, Nunome M, Nakano M, Matsuda Y, Sato Y, Mizuno H, Iwasato T, Ishii Y, Kondoh H. Live imaging of avian epiblast and anterior mesendoderm grafting reveals the complexity of cell dynamics during early brain development. Development 2022; 149:274289. [PMID: 35132990 PMCID: PMC9017232 DOI: 10.1242/dev.199999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 01/18/2022] [Indexed: 11/20/2022]
Abstract
Despite previous intensive investigations on epiblast cell migration in avian embryos during primitive streak development before stage (st.) 4, this migration at later stages of brain development has remained uninvestigated. By live imaging of epiblast cells sparsely labeled with green fluorescence protein, we investigated anterior epiblast cell migration to form individual brain portions. Anterior epiblast cells from a broad area migrated collectively towards the head axis during st. 5-7 at a rate of 70-110 µm/h, changing directions from diagonal to parallel and forming the brain portions and abutting head ectoderm. This analysis revised the previously published head portion precursor map in anterior epiblasts at st. 4/5. Grafting outside the brain precursor region of mCherry-expressing nodes producing anterior mesendoderm (AME) or isolated AME tissues elicited new cell migration towards ectopic AME tissues. These locally convergent cells developed into secondary brains with portions that depended on the ectopic AME position in the anterior epiblast. Thus, anterior epiblast cells are bipotent for brain/head ectoderm development with given brain portion specificities. A brain portion potential map is proposed, also accounting for previous observations. Summary: The first high-resolution live imaging of anterior epiblast cells at the brain-forming stages in avian embryos is reported, revealing their long-distance migration and interaction with the anterior mesendoderm to form brain tissues.
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Affiliation(s)
- Koya Yoshihi
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Kagayaki Kato
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
| | - Hideaki Iida
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Machiko Teramoto
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Akihito Kawamura
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Yusaku Watanabe
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Mitsuo Nunome
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Mikiharu Nakano
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoichi Matsuda
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yuki Sato
- Department of Anatomy and Cell Biology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hidenobu Mizuno
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan.,International Research Center for Medical Sciences (IRCMS), Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto City 860-0811, Japan
| | - Takuji Iwasato
- Laboratory of Mammalian Neural Circuits, National Institute of Genetics (NIG), Mishima, Shizuoka 411-8540, Japan
| | - Yasuo Ishii
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.,Department of Biology, School of Medicine, Tokyo Women's Medical University, Shinjuku-ku, Tokyo 162-8666, Japan
| | - Hisato Kondoh
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.,Institute for Comprehensive Research, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan.,JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan
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5
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Sagai T, Amano T, Maeno A, Ajima R, Shiroishi T. SHH signaling mediated by a prechordal and brain enhancer controls forebrain organization. Proc Natl Acad Sci U S A 2019; 116:23636-23642. [PMID: 31685615 PMCID: PMC6876251 DOI: 10.1073/pnas.1901732116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Sonic hedgehog (SHH) signaling plays a pivotal role in 2 different phases during brain development. Early SHH signaling derived from the prechordal plate (PrCP) triggers secondary Shh induction in the forebrain, which overlies the PrCP, and the induced SHH signaling, in turn, directs late neuronal differentiation of the forebrain. Consequently, Shh regulation in the PrCP is crucial for initiation of forebrain development. However, no enhancer that regulates prechordal Shh expression has yet been found. Here, we identified a prechordal enhancer, named SBE7, in the vicinity of a cluster of known forebrain enhancers for Shh This enhancer also directs Shh expression in the ventral midline of the forebrain, which receives the prechordal SHH signal. Thus, the identified enhancer acts not only for the initiation of Shh regulation in the PrCP but also for subsequent Shh induction in the forebrain. Indeed, removal of the enhancer from the mouse genome markedly down-regulated the expression of Shh in the rostral domains of the axial mesoderm and in the ventral midline of the forebrain and hypothalamus in the mouse embryo, and caused a craniofacial abnormality similar to human holoprosencephaly (HPE). These findings demonstrate that SHH signaling mediated by the newly identified enhancer is essential for development and growth of the ventral midline of the forebrain and hypothalamus. Understanding of the Shh regulation governed by this prechordal and brain enhancer provides an insight into the mechanism underlying craniofacial morphogenesis and the etiology of HPE.
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Affiliation(s)
- Tomoko Sagai
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan
- Information Resource Research Center, Association for Propagation of the Knowledge of Genetics, Mishima 411-8540, Japan
| | - Takanori Amano
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan
- Next Generation Human Disease Model Team, RIKEN BioResource Research Center, Tsukuba 305-0074, Japan
- Department of Genetics, SOKENDAI, Mishima 411-8540, Japan
| | - Akiteru Maeno
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan
- Plant Cytogenetics Laboratory, National Institute of Genetics, Mishima 411-8540, Japan
| | - Rieko Ajima
- Department of Genetics, SOKENDAI, Mishima 411-8540, Japan
- Mammalian Development Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan
- Mouse Research Supporting Unit, National Institute of Genetics, Mishima 411-8540, Japan
| | - Toshihiko Shiroishi
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima 411-8540, Japan;
- Department of Genetics, SOKENDAI, Mishima 411-8540, Japan
- RIKEN BioResource Research Center, Tsukuba 305-0074, Japan
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6
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Tuazon FB, Mullins MC. Temporally coordinated signals progressively pattern the anteroposterior and dorsoventral body axes. Semin Cell Dev Biol 2015; 42:118-33. [PMID: 26123688 PMCID: PMC4562868 DOI: 10.1016/j.semcdb.2015.06.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 06/16/2015] [Indexed: 10/23/2022]
Abstract
The vertebrate body plan is established through the precise spatiotemporal coordination of morphogen signaling pathways that pattern the anteroposterior (AP) and dorsoventral (DV) axes. Patterning along the AP axis is directed by posteriorizing signals Wnt, fibroblast growth factor (FGF), Nodal, and retinoic acid (RA), while patterning along the DV axis is directed by bone morphogenetic proteins (BMP) ventralizing signals. This review addresses the current understanding of how Wnt, FGF, RA and BMP pattern distinct AP and DV cell fates during early development and how their signaling mechanisms are coordinated to concomitantly pattern AP and DV tissues.
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Affiliation(s)
- Francesca B Tuazon
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 1152 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6058, United States
| | - Mary C Mullins
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 1152 BRBII/III, 421 Curie Boulevard, Philadelphia, PA 19104-6058, United States.
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7
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Koike S, Yutoh Y, Keino-Masu K, Noji S, Masu M, Ohuchi H. Autotaxin is required for the cranial neural tube closure and establishment of the midbrain-hindbrain boundary during mouse development. Dev Dyn 2011; 240:413-21. [PMID: 21246658 DOI: 10.1002/dvdy.22543] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/01/2010] [Indexed: 11/07/2022] Open
Abstract
Autotaxin (ATX) is a lysophospholipid-generating exoenzyme expressed in embryonic and adult neural tissues. We previously showed that ATX is expressed in the neural organizing centers, anterior head process, and midbrain-hindbrain boundary (MHB). To elucidate the role of ATX during neural development, here we examined the neural phenotypes of ATX-deficient mice. Expression analysis of neural marker genes revealed that lateral expansion of the rostral forebrain is reduced and establishment of the MHB is compromised as early as the late headfold stage in ATX mutant embryos. Moreover, ATX mutant embryos fail to complete cranial neural tube closure. These results indicate that ATX is essential for cranial neurulation and MHB establishment.
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Affiliation(s)
- Seiichi Koike
- Department of Molecular Neurobiology, Institute of Basic Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
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8
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Sagha M, Karbalaie K, Tanhaee S, Esfandiari E, Salehi H, Sadeghi-Aliabadi H, Razavi S, Nasr-Esfahani MH, Baharvand H. Neural Induction in Mouse Embryonic Stem Cells by Co-Culturing With Chicken Somites. Stem Cells Dev 2009; 18:1351-60. [DOI: 10.1089/scd.2008.0341] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Mohsen Sagha
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
- Department of Anatomical Sciences, School of Medicine, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Khadijeh Karbalaie
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Somaieh Tanhaee
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Ebrahim Esfandiari
- Department of Anatomical Sciences, School of Medicine, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Hossein Salehi
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Hojjat Sadeghi-Aliabadi
- Department of Pharmaceutical Chemistry, School of Pharmacy and Esfahan Pharmaceutical Research Center, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Shahnaz Razavi
- Department of Anatomical Sciences, School of Medicine, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Mohammad Hossein Nasr-Esfahani
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Hossein Baharvand
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
- Department of Developmental Biology, University of Science and Culture, Iranian Academic Center for Education, Culture, and Research (ACECR), Tehran, Iran
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9
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FOLEY ANNC, STERN CLAUDIOD. Evolution of vertebrate forebrain development: how many different mechanisms? J Anat 2009. [DOI: 10.1046/j.1469-7580.199.parts1-2.5.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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10
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García-Calero E, Fernández-Garre P, Martínez S, Puelles L. Early mammillary pouch specification in the course of prechordal ventralization of the forebrain tegmentum. Dev Biol 2008; 320:366-77. [PMID: 18597750 DOI: 10.1016/j.ydbio.2008.05.545] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 04/28/2008] [Accepted: 05/20/2008] [Indexed: 10/22/2022]
Abstract
The mammillary body, a ventral specialization of the caudal hypothalamus, lies close to the transition between epichordal and prechordal parts of the forebrain (Puelles and Rubenstein, 2003). This report examines its presumed causal connection with either prechordal or notochordal mesodermal induction, as well as the timing of its specification, in the context of early ventral forebrain patterning. It was recently found that the ephrin receptor gene EphA7 is selectively expressed in the mammillary pouch from early stages of development (HH14: García-Calero et al., 2006). We used mammillary EphA7 expression as well as ventral hypothalamic expression of the gene markers Nkx2.1 and Shh to analyze experimental effects on mammillary specification and morphogenesis after axial mesoderm ablation at stages HH4+ to HH6. Progressively delayed ablation of the prechordal plate revealed its sequential implication in molecular specification of the entire ventral forebrain, including the mammillary and tuberal regions of the hypothalamus. We observed differential contact requirements for induction by the prechordal plate of all the forebrain regions expressing Shh and Nkx2.1, including distant subpallial ones. In contrast, ablation of the anterior notochordal tip at these stages did not elicit significant patterning changes, particularly no effects on mammillary EphA7 expression or mammillary pouch development.
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Affiliation(s)
- Elena García-Calero
- Department of Human Anatomy and Psychobiology and CIBER en Enfermedades Raras, U736, University of Murcia, Campus de Espinardo, 30100, Murcia, Spain.
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11
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Live Imaging and Genetic Analysis of Mouse Notochord Formation Reveals Regional Morphogenetic Mechanisms. Dev Cell 2007; 13:884-96. [DOI: 10.1016/j.devcel.2007.10.016] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Revised: 10/04/2007] [Accepted: 10/29/2007] [Indexed: 11/20/2022]
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12
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Albazerchi A, Stern CD. A role for the hypoblast (AVE) in the initiation of neural induction, independent of its ability to position the primitive streak. Dev Biol 2006; 301:489-503. [PMID: 17010966 DOI: 10.1016/j.ydbio.2006.08.057] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 07/29/2006] [Accepted: 08/23/2006] [Indexed: 10/24/2022]
Abstract
The mouse anterior visceral endoderm (AVE) has been implicated in embryonic polarity: it helps to position the primitive streak and some have suggested that it might act as a "head organizer", inducing forebrain directly. Here we explore the role of the hypoblast (the chick equivalent of the AVE) in the early steps of neural induction and patterning. We report that the hypoblast can induce a set of very early markers that are later expressed in the nervous system and in the forebrain, but only transiently. Different combinations of signals are responsible for different aspects of this early transient induction: FGF initiates expression of Sox3 and ERNI, retinoic acid can induce Cyp26A1 and only a combination of low levels of FGF8 together with Wnt- and BMP-antagonists can induce Otx2. BMP- and Wnt-antagonists and retinoic acid, in different combinations, can maintain the otherwise transient induction of these markers. However, neither the hypoblast nor any of these factors or combinations thereof can induce the definitive neural marker Sox2 or the formation of a mature neural plate or a forebrain, suggesting that the hypoblast is not a head organizer and that other signals remain to be identified. Interestingly, FGF and retinoids, generally considered as caudalizing factors, are shown here to play a role in the induction of a transient "pre-neural/pre-forebrain" state.
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Affiliation(s)
- Amanda Albazerchi
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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13
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Wittler L, Kessel M. The acquisition of neural fate in the chick. Mech Dev 2005; 121:1031-42. [PMID: 15296969 DOI: 10.1016/j.mod.2004.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Revised: 05/09/2004] [Accepted: 05/09/2004] [Indexed: 01/10/2023]
Abstract
Neural development in the chick embryo is now understood in great detail on a cellular and a molecular level. It begins already before gastrulation, when a separation of neural and epidermal cell fates occurs under the control of FGF and BMP/Wnt signalling, respectively. This early specification becomes further refined around the tip of the primitive streak, until finally the anterior-posterior level of the neuroectoderm becomes established through progressive caudalization. In this review we focus on processes in the chick embryo and put classical and more recent molecular data into a coherent scenario.
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Affiliation(s)
- Lars Wittler
- Department of Molecular Cell Biology, Max-Planck-Institut für biophysikalische Chemie, Am Fassberg 11, 37077 Göttingen, Germany.
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14
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Chapman SC, Schubert FR, Schoenwolf GC, Lumsden A. Analysis of spatial and temporal gene expression patterns in blastula and gastrula stage chick embryos. Dev Biol 2002; 245:187-99. [PMID: 11969265 DOI: 10.1006/dbio.2002.0641] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Studies on the genetic basis of rostral-caudal specification, neural induction, and head development require knowledge of the relevant gene expression patterns. Gaps in our understanding of gene expression have led us to examine the detailed spatiotemporal expression patterns of 19 genes implicated in early development, to learn more about their potential role in specifying and patterning early developmental processes leading to head formation. Here, we report the expression patterns of these markers in blastula- and gastrula-stage chick embryos, using whole-mount in situ hybridisation. Nodal, Fgf8, Bmp7, Chordin, Lim1, Hnf3beta, Otx2, Goosecoid, Cerberus, Hex, Dickkopf1, and Crescent are all already expressed by the time the egg is laid. When the primitive streak has reached its full length, a later group of genes, including Ganf, Six3, Bmp2, Bmp4, Noggin, Follistatin, and Qin (BF1), begins to be expressed. We reassess current models of early rostral patterning based on the analysis of these dynamic spatiotemporal expression patterns.
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Affiliation(s)
- Susan C Chapman
- MRC Centre for Developmental Neurobiology, Kings College London, New Hunts House, London SE1 1UL, United Kingdom.
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15
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Hallonet M, Kaestner KH, Martin-Parras L, Sasaki H, Betz UAK, Ang SL. Maintenance of the specification of the anterior definitive endoderm and forebrain depends on the axial mesendoderm: a study using HNF3beta/Foxa2 conditional mutants. Dev Biol 2002; 243:20-33. [PMID: 11846474 DOI: 10.1006/dbio.2001.0536] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In mouse embryo, the early induction of the head region depends on signals from the anterior visceral endoderm (AVE) and the anterior primitive streak. Subsequently, node derivatives, including anterior definitive endoderm and axial mesendoderm, are thought to play a role in the maintenance and elaboration of anterior neural character. Foxa2 encodes a winged-helix transcription factor expressed in signaling centers required for head development, including the AVE, anterior primitive streak, anterior definitive endoderm, and axial mesendoderm. To address Foxa2 function during formation of the head, we used conditional mutants in which Foxa2 function is preserved in extraembryonic tissues during early embryonic stages and inactivated in embryonic tissues after the onset of gastrulation. In Foxa2 conditional mutants, the anterior neural plate and anterior definitive endoderm were initially specified. In contrast, the axial mesendoderm failed to differentiate. At later stages, specification of the anterior neural plate and anterior definitive endoderm was shown to be labile. As a result, head truncations were observed in Foxa2 conditional mutants. Our results therefore indicate that anterior definitive endoderm alone is not sufficient to maintain anterior head specification and that an interaction between the axial mesendoderm and the anterior definitive endoderm is required for proper specification of the endoderm. Foxa2 therefore plays an integral role in the formation of axial mesendoderm, which is required to maintain the specification of the forebrain and the anterior definitive endoderm.
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Affiliation(s)
- Marc Hallonet
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université Louis Pasteur, C.U. de Strasbourg, Illkirch, France
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Mathis L, Kulesa PM, Fraser SE. FGF receptor signalling is required to maintain neural progenitors during Hensen's node progression. Nat Cell Biol 2001; 3:559-66. [PMID: 11389440 DOI: 10.1038/35078535] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previous analyses of labelled clones of cells within the developing nervous system of the mouse have indicated that descendants are initially dispersed rostrocaudally followed by more local proliferation, which is consistent with the progressing node's contributing descendants from a resident population of progenitor cells as it advances caudally. Here we electroporated an expression vector encoding green fluorescent protein into the chicken embryo near Hensen's node to test and confirm the pattern inferred in the mouse. This provides a model in which a proliferative stem zone is maintained in the node by a localized signal; those cells that are displaced out of the stem zone go on to contribute to the growing axis. To test whether fibroblast growth factor (FGF) signalling could be involved in the maintenance of the stem zone, we co-electroporated a dominant-negative FGF receptor with a lineage marker, and found that it markedly alters the elongation of the spinal cord primordium. The results indicate that FGF receptor signalling promotes the continuous development of the posterior nervous system by maintaining presumptive neural progenitors in the region near Hensen's node. This offers a potential explanation for the mixed findings on FGF in the growth and patterning of the embryonic axis.
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Affiliation(s)
- L Mathis
- Biological Imaging Center, Beckman Institute 139-74, California Institute of Technology, Pasadena, California 91125, USA
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17
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Abstract
For three-quarters of a century, developmental biologists have been asking how the nervous system is specified as distinct from the rest of the ectoderm during early development, and how it becomes subdivided initially into distinct regions such as forebrain, midbrain, hindbrain and spinal cord. The two events of 'neural induction' and 'early neural patterning' seem to be intertwined, and many models have been put forward to explain how these processes work at a molecular level. Here I consider early neural patterning and discuss the evidence for and against the two most popular models proposed for its explanation: the idea that multiple signalling centres (organizers) are responsible for inducing different regions of the nervous system, and a model first articulated by Nieuwkoop that invokes two steps (activation/transformation) necessary for neural patterning. As recent evidence from several systems challenges both models, I propose a modification of Nieuwkoop's model that most easily accommodates both classical and more recent data, and end by outlining some possible directions for future research.
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Affiliation(s)
- C D Stern
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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Wurst W, Bally-Cuif L. Neural plate patterning: upstream and downstream of the isthmic organizer. Nat Rev Neurosci 2001; 2:99-108. [PMID: 11253000 DOI: 10.1038/35053516] [Citation(s) in RCA: 397] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Two organizing centres operate at long-range distances within the anterior neural plate to pattern the forebrain, midbrain and hindbrain. Important progress has been made in understanding the formation and function of one of these organizing centres, the isthmic organizer, which controls the development of the midbrain and anterior hindbrain. Here we review our current knowledge on the identity, localization and maintenance of the isthmic organizer, as well as on the molecular cascades that underlie the activity of this organizing centre.
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Affiliation(s)
- W Wurst
- Institute of Mammalian Genetics, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany.
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19
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Abstract
This review discusses formation of the vertebrate anteroposterior (AP) axis, focusing on the dorsal ectoderm, which gives rise to the nervous system, using the frog Xenopus as a model. After summarizing classical models of AP neural patterning, we describe recent molecular studies that are encouraging re-examination of these models. Such studies have shown that AP ectodermal patterning occurs by the onset of gastrulation, much earlier than previously thought. The identity of tissues that determine AP pattern is discussed, and the definition of the Organizer is reconsidered. The activity of factors secreted by inducing tissues in early patterning decisions is assessed and formulated into a revised model for Xenopus AP neural patterning. Finally, AP ectodermal patterning in Xenopus dorsal ectoderm is compared to that of other germ layers, and to other vertebrates.
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Affiliation(s)
- J Gamse
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Foley AC, Skromne I, Stern CD. Reconciling different models of forebrain induction and patterning: a dual role for the hypoblast. Development 2000; 127:3839-54. [PMID: 10934028 DOI: 10.1242/dev.127.17.3839] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Several models have been proposed for the generation of the rostral nervous system. Among them, Nieuwkoop's activation/transformation hypothesis and Spemann's idea of separate head and trunk/tail organizers have been particularly favoured recently. In the mouse, the finding that the visceral endoderm (VE) is required for forebrain development has been interpreted as support for the latter model. Here we argue that the chick hypoblast is equivalent to the mouse VE, based on fate, expression of molecular markers and characteristic anterior movements around the time of gastrulation. We show that the hypoblast does not fit the criteria for a head organizer because it does not induce neural tissue from naive epiblast, nor can it change the regional identity of neural tissue. However, the hypoblast does induce transient expression of the early markers Sox3 and Otx2. The spreading of the hypoblast also directs cell movements in the adjacent epiblast, such that the prospective forebrain is kept at a distance from the organizer at the tip of the primitive streak. We propose that this movement is important to protect the forebrain from the caudalizing influence of the organizer. This dual role of the hypoblast is more consistent with the Nieuwkoop model than with the notion of separate organizers, and accommodates the available data from mouse and other vertebrates.
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Affiliation(s)
- A C Foley
- Department of Genetics and Development, Columbia University, New York, NY 10032, USA
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21
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Camus A, Davidson BP, Billiards S, Khoo P, Rivera-Pérez JA, Wakamiya M, Behringer RR, Tam PP. The morphogenetic role of midline mesendoderm and ectoderm in the development of the forebrain and the midbrain of the mouse embryo. Development 2000; 127:1799-813. [PMID: 10751169 DOI: 10.1242/dev.127.9.1799] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The anterior midline tissue (AML) of the late gastrula mouse embryo comprises the axial mesendoderm and the ventral neuroectoderm of the prospective forebrain, midbrain and rostral hindbrain. In this study, we have investigated the morphogenetic role of defined segments of the AML by testing their inductive and patterning activity and by assessing the impact of their ablation on the patterning of the neural tube at the early-somite-stage. Both rostral and caudal segments of the AML were found to induce neural gene activity in the host tissue; however, the de novo gene activity did not show any regional characteristic that might be correlated with the segmental origin of the AML. Removal of the rostral AML that contains the prechordal plate resulted in a truncation of the head accompanied by the loss of several forebrain markers. However, the remaining tissues reconstituted Gsc and Shh activity and expressed the ventral forebrain marker Nkx2.1. Furthermore, analysis of Gsc-deficient embryos reveals that the morphogenetic function of the rostral AML requires Gsc activity. Removal of the caudal AML led to a complete loss of midline molecular markers anterior to the 4th somite. In addition, Nkx2.1 expression was not detected in the ventral neural tube. The maintenance and function of the rostral AML therefore require inductive signals emanating from the caudal AML. Our results point to a role for AML in the refinement of the anteroposterior patterning and morphogenesis of the brain.
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Affiliation(s)
- A Camus
- Embryology Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, NSW 2145, Australia.
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