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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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2
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Solovieva T, Wilson V, Stern CD. A niche for axial stem cells - A cellular perspective in amniotes. Dev Biol 2022; 490:13-21. [PMID: 35779606 PMCID: PMC10497457 DOI: 10.1016/j.ydbio.2022.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 05/19/2022] [Accepted: 06/25/2022] [Indexed: 11/24/2022]
Abstract
The head-tail axis in birds and mammals develops from a growth zone in the tail-end, which contains the node. This growth zone then forms the tailbud. Labelling experiments have shown that while many cells leave the node and tailbud to contribute to axial (notochord, floorplate) and paraxial (somite) structures, some cells remain resident in the node and tailbud. Could these cells be resident axial stem cells? If so, do the node and tailbud represent an instructive stem cell niche that specifies and maintains these stem cells? Serial transplantation and single cell labelling studies support the existence of self-renewing stem cells and heterotopic transplantations suggest that the node can instruct such self-renewing behaviour. However, only single cell manipulations can reveal whether self-renewing behaviour occurs at the level of a cell population (asymmetric or symmetric cell divisions) or at the level of single cells (asymmetric divisions only). We combine data on resident cells in the node and tailbud and review it in the context of axial development in chick and mouse, summarising our current understanding of axial stem cells and their niche and highlighting future directions of interest.
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Affiliation(s)
- Tatiana Solovieva
- Department of Cell and Developmental Biology, University College London, UK
| | - Valerie Wilson
- Centre for Regenerative Medicine, The University of Edinburgh, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, UK.
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3
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Martin BL, Steventon B. A fishy tail: Insights into the cell and molecular biology of neuromesodermal cells from zebrafish embryos. Dev Biol 2022; 487:67-73. [PMID: 35525020 DOI: 10.1016/j.ydbio.2022.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/29/2022] [Accepted: 04/26/2022] [Indexed: 11/03/2022]
Abstract
Vertebrate embryos establish their primary body axis in a conserved progressive fashion from the anterior to the posterior. During this process, a posteriorly localized neuromesodermal cell population called neuromesodermal progenitors (NMps) plays a critical role in contributing new cells to the spinal cord and mesoderm as the embryo elongates. Defects in neuromesodermal population development can cause severe disruptions to the formation of the body posterior to the head. Given their importance during development and their potential, some of which has already been realized, for revealing new methods of in vitro tissue generation, there is great interest in better understanding NMp biology. The zebrafish model system has been instrumental in advancing our understanding of the molecular and cellular attributes of the NM cell population and its derivatives. In this review, we focus on our current understanding of the zebrafish NM population and its contribution to body axis formation, with particular emphasis on the lineage potency, morphogenesis, and niche factors that promote or inhibit differentiation.
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Affiliation(s)
- Benjamin L Martin
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794-5215, USA.
| | - Benjamin Steventon
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
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4
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Fulton T, Verd B, Steventon B. The unappreciated generative role of cell movements in pattern formation. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211293. [PMID: 35601454 PMCID: PMC9043703 DOI: 10.1098/rsos.211293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 04/05/2022] [Indexed: 06/15/2023]
Abstract
The mechanisms underpinning the formation of patterned cellular landscapes has been the subject of extensive study as a fundamental problem of developmental biology. In most cases, attention has been given to situations in which cell movements are negligible, allowing researchers to focus on the cell-extrinsic signalling mechanisms, and intrinsic gene regulatory interactions that lead to pattern emergence at the tissue level. However, in many scenarios during development, cells rapidly change their neighbour relationships in order to drive tissue morphogenesis, while also undergoing patterning. To draw attention to the ubiquity of this problem and propose methodologies that will accommodate morphogenesis into the study of pattern formation, we review the current approaches to studying pattern formation in both static and motile cellular environments. We then consider how the cell movements themselves may contribute to the generation of pattern, rather than hinder it, with both a species specific and evolutionary viewpoint.
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Affiliation(s)
- Timothy Fulton
- Department of Genetics, University of Cambridge, Cambridge, UK
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Berta Verd
- Department of Genetics, University of Cambridge, Cambridge, UK
- Department of Zoology, University of Oxford, Oxford, UK
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5
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Solovieva T, Lu HC, Moverley A, Plachta N, Stern CD. The embryonic node behaves as an instructive stem cell niche for axial elongation. Proc Natl Acad Sci U S A 2022. [PMID: 35101917 DOI: 10.1101/2020.11.10.376913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
In warm-blooded vertebrate embryos (mammals and birds), the axial tissues of the body form from a growth zone at the tail end, Hensen's node, which generates neural, mesodermal, and endodermal structures along the midline. While most cells only pass through this region, the node has been suggested to contain a small population of resident stem cells. However, it is unknown whether the rest of the node constitutes an instructive niche that specifies this self-renewal behavior. Here, we use heterotopic transplantation of groups and single cells and show that cells not destined to enter the node can become resident and self-renew. Long-term resident cells are restricted to the posterior part of the node and single-cell RNA-sequencing reveals that the majority of these resident cells preferentially express G2/M phase cell-cycle-related genes. These results provide strong evidence that the node functions as a niche to maintain self-renewal of axial progenitors.
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Affiliation(s)
- Tatiana Solovieva
- Department of Cell and Developmental Biology, University College London, WC1E 6BT London, United Kingdom
| | - Hui-Chun Lu
- Department of Cell and Developmental Biology, University College London, WC1E 6BT London, United Kingdom
| | - Adam Moverley
- Department of Cell and Developmental Biology, University College London, WC1E 6BT London, United Kingdom
- Institute of Molecular Cell Biology, A*STAR, 138673 Proteos, Singapore
| | - Nicolas Plachta
- Institute of Molecular Cell Biology, A*STAR, 138673 Proteos, Singapore
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, WC1E 6BT London, United Kingdom;
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6
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The embryonic node behaves as an instructive stem cell niche for axial elongation. Proc Natl Acad Sci U S A 2022; 119:2108935119. [PMID: 35101917 PMCID: PMC8812687 DOI: 10.1073/pnas.2108935119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2021] [Indexed: 01/30/2023] Open
Abstract
Previous studies have suggested that the amniote node (Hensen’s node) contains a small population of self-renewing resident cells whose progeny progressively lay down axial tissues, including notochord and somites. This can only be demonstrated definitively at the level of single cells. Here we ask whether the node is an environment that can confer this behavior on cells that enter it. We challenge single cells in vivo and mRNA-profile these cells to demonstrate that the node can indeed do this, and thus show that the node acts as an instructive niche. In warm-blooded vertebrate embryos (mammals and birds), the axial tissues of the body form from a growth zone at the tail end, Hensen’s node, which generates neural, mesodermal, and endodermal structures along the midline. While most cells only pass through this region, the node has been suggested to contain a small population of resident stem cells. However, it is unknown whether the rest of the node constitutes an instructive niche that specifies this self-renewal behavior. Here, we use heterotopic transplantation of groups and single cells and show that cells not destined to enter the node can become resident and self-renew. Long-term resident cells are restricted to the posterior part of the node and single-cell RNA-sequencing reveals that the majority of these resident cells preferentially express G2/M phase cell-cycle–related genes. These results provide strong evidence that the node functions as a niche to maintain self-renewal of axial progenitors.
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7
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Yan Y, Wang Q. BMP Signaling: Lighting up the Way for Embryonic Dorsoventral Patterning. Front Cell Dev Biol 2022; 9:799772. [PMID: 35036406 PMCID: PMC8753366 DOI: 10.3389/fcell.2021.799772] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
One of the most significant events during early embryonic development is the establishment of a basic embryonic body plan, which is defined by anteroposterior, dorsoventral (DV), and left-right axes. It is well-known that the morphogen gradient created by BMP signaling activity is crucial for DV axis patterning across a diverse set of vertebrates. The regulation of BMP signaling during DV patterning has been strongly conserved across evolution. This is a remarkable regulatory and evolutionary feat, as the BMP gradient has been maintained despite the tremendous variation in embryonic size and shape across species. Interestingly, the embryonic DV axis exhibits robust stability, even in face of variations in BMP signaling. Multiple lines of genetic, molecular, and embryological evidence have suggested that numerous BMP signaling components and their attendant regulators act in concert to shape the developing DV axis. In this review, we summarize the current knowledge of the function and regulation of BMP signaling in DV patterning. Throughout, we focus specifically on popular model animals, such as Xenopus and zebrafish, highlighting the similarities and differences of the regulatory networks between species. We also review recent advances regarding the molecular nature of DV patterning, including the initiation of the DV axis, the formation of the BMP gradient, and the regulatory molecular mechanisms behind BMP signaling during the establishment of the DV axis. Collectively, this review will help clarify our current understanding of the molecular nature of DV axis formation.
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Affiliation(s)
- Yifang Yan
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.,National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China.,Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China.,Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China
| | - Qiang Wang
- State Key Laboratory of Membrane Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
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8
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Dissecting the Complexity of Early Heart Progenitor Cells. J Cardiovasc Dev Dis 2021; 9:jcdd9010005. [PMID: 35050215 PMCID: PMC8779398 DOI: 10.3390/jcdd9010005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 12/23/2022] Open
Abstract
Early heart development depends on the coordinated participation of heterogeneous cell sources. As pioneer work from Adriana C. Gittenberger-de Groot demonstrated, characterizing these distinct cell sources helps us to understand congenital heart defects. Despite decades of research on the segregation of lineages that form the primitive heart tube, we are far from understanding its full complexity. Currently, single-cell approaches are providing an unprecedented level of detail on cellular heterogeneity, offering new opportunities to decipher its functional role. In this review, we will focus on three key aspects of early heart morphogenesis: First, the segregation of myocardial and endocardial lineages, which yields an early lineage diversification in cardiac development; second, the signaling cues driving differentiation in these progenitor cells; and third, the transcriptional heterogeneity of cardiomyocyte progenitors of the primitive heart tube. Finally, we discuss how single-cell transcriptomics and epigenomics, together with live imaging and functional analyses, will likely transform the way we delve into the complexity of cardiac development and its links with congenital defects.
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9
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Kumar V, Park S, Lee U, Kim J. The Organizer and Its Signaling in Embryonic Development. J Dev Biol 2021; 9:jdb9040047. [PMID: 34842722 PMCID: PMC8628936 DOI: 10.3390/jdb9040047] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 12/25/2022] Open
Abstract
Germ layer specification and axis formation are crucial events in embryonic development. The Spemann organizer regulates the early developmental processes by multiple regulatory mechanisms. This review focuses on the responsive signaling in organizer formation and how the organizer orchestrates the germ layer specification in vertebrates. Accumulated evidence indicates that the organizer influences embryonic development by dual signaling. Two parallel processes, the migration of the organizer’s cells, followed by the transcriptional activation/deactivation of target genes, and the diffusion of secreting molecules, collectively direct the early development. Finally, we take an in-depth look at active signaling that originates from the organizer and involves germ layer specification and patterning.
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Affiliation(s)
- Vijay Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea;
| | - Soochul Park
- Department of Biological Sciences, Sookmyung Women’s University, Seoul 04310, Korea;
| | - Unjoo Lee
- Department of Electrical Engineering, Hallym University, Chuncheon 24252, Korea
- Correspondence: (U.L.); (J.K.); Tel.: +82-33-248-2544 (J.K.); Fax: +82-33-244-8425 (J.K.)
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Chuncheon 24252, Korea;
- Correspondence: (U.L.); (J.K.); Tel.: +82-33-248-2544 (J.K.); Fax: +82-33-244-8425 (J.K.)
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10
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Romanos M, Allio G, Roussigné M, Combres L, Escalas N, Soula C, Médevielle F, Steventon B, Trescases A, Bénazéraf B. Cell-to-cell heterogeneity in Sox2 and Bra expression guides progenitor motility and destiny. eLife 2021; 10:e66588. [PMID: 34607629 PMCID: PMC8492064 DOI: 10.7554/elife.66588] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 09/13/2021] [Indexed: 12/13/2022] Open
Abstract
Although cell-to-cell heterogeneity in gene and protein expression within cell populations has been widely documented, we know little about its biological functions. By studying progenitors of the posterior region of bird embryos, we found that expression levels of transcription factors Sox2 and Bra, respectively involved in neural tube (NT) and mesoderm specification, display a high degree of cell-to-cell heterogeneity. By combining forced expression and downregulation approaches with time-lapse imaging, we demonstrate that Sox2-to-Bra ratio guides progenitor's motility and their ability to stay in or exit the progenitor zone to integrate neural or mesodermal tissues. Indeed, high Bra levels confer high motility that pushes cells to join the paraxial mesoderm, while high levels of Sox2 tend to inhibit cell movement forcing cells to integrate the NT. Mathematical modeling captures the importance of cell motility regulation in this process and further suggests that randomness in Sox2/Bra cell-to-cell distribution favors cell rearrangements and tissue shape conservation.
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Affiliation(s)
- Michèle Romanos
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
- Institut de Mathématiques de Toulouse UMR 5219, Université de ToulouseToulouseFrance
| | - Guillaume Allio
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
| | - Myriam Roussigné
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
| | - Léa Combres
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
| | - Nathalie Escalas
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
| | - Cathy Soula
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
| | - François Médevielle
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
| | | | - Ariane Trescases
- Institut de Mathématiques de Toulouse UMR 5219, Université de ToulouseToulouseFrance
| | - Bertrand Bénazéraf
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPSToulouseFrance
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11
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Steventon B, Busby L, Arias AM. Establishment of the vertebrate body plan: Rethinking gastrulation through stem cell models of early embryogenesis. Dev Cell 2021; 56:2405-2418. [PMID: 34520764 DOI: 10.1016/j.devcel.2021.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 07/20/2021] [Accepted: 08/14/2021] [Indexed: 12/28/2022]
Abstract
A striking property of vertebrate embryos is the emergence of a conserved body plan across a wide range of organisms through the process of gastrulation. As the body plan unfolds, gene regulatory networks (GRNs) and multicellular interactions (cell regulatory networks, CRNs) combine to generate a conserved set of morphogenetic events that lead to the phylotypic stage. Interrogation of these multilevel interactions requires manipulation of the mechanical environment, which is difficult in vivo. We review recent studies of stem cell models of early embryogenesis from different species showing that, independent of species origin, cells in culture form similar structures. The main difference between embryos and in vitro models is the boundary conditions of the multicellular ensembles. We discuss these observations and suggest that the mechanical and geometric boundary conditions of different embryos before gastrulation hide a morphogenetic ground state that is revealed in the stem-cell-based models of embryo development.
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Affiliation(s)
| | - Lara Busby
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Alfonso Martinez Arias
- Systems Bioengineering, DCEXS, Universidad Pompeu Fabra, Doctor Aiguader, 88 ICREA, Pag Lluis Companys 23, Barcelona, Spain.
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12
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Itoh K, Ossipova O, Sokol SY. Pinhead antagonizes Admp to promote notochord formation. iScience 2021; 24:102520. [PMID: 34142034 PMCID: PMC8188501 DOI: 10.1016/j.isci.2021.102520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 03/18/2021] [Accepted: 05/05/2021] [Indexed: 12/05/2022] Open
Abstract
Dorsoventral patterning of a vertebrate embryo critically depends on the activity of Smad1 that mediates signaling by BMP proteins, anti-dorsalizing morphogenetic protein (Admp), and their antagonists. Pinhead (Pnhd), a cystine-knot-containing secreted protein, is expressed in the ventrolateral mesoderm during Xenopus gastrulation; however, its molecular targets and signaling mechanisms have not been fully elucidated. Our mass spectrometry-based screen of the gastrula secretome identified Admp as Pnhd-associated protein. We show that Pnhd binds Admp and inhibits its ventralizing activity by reducing Smad1 phosphorylation and its transcriptional targets. Importantly, Pnhd depletion further increased phospho-Smad1 levels in the presence of Admp. Furthermore, Pnhd synergized with Chordin and a truncated BMP4 receptor in the induction of notochord markers in ectoderm cells, and Pnhd-depleted embryos displayed notochord defects. Our findings suggest that Pnhd binds and inactivates Admp to promote notochord development. We propose that the interaction between Admp and Pnhd refines Smad1 activity gradients during vertebrate gastrulation.
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Affiliation(s)
- Keiji Itoh
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Olga Ossipova
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, USA
| | - Sergei Y. Sokol
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, USA
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13
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Ossipova O, Itoh K, Radu A, Ezan J, Sokol SY. Pinhead signaling regulates mesoderm heterogeneity via the FGF receptor-dependent pathway. Development 2020; 147:dev.188094. [PMID: 32859582 DOI: 10.1242/dev.188094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 08/04/2020] [Indexed: 12/29/2022]
Abstract
Among the three embryonic germ layers, the mesoderm plays a central role in the establishment of the vertebrate body plan. The mesoderm is specified by secreted signaling proteins from the FGF, Nodal, BMP and Wnt families. No new classes of extracellular mesoderm-inducing factors have been identified in more than two decades. Here, we show that the pinhead (pnhd) gene encodes a secreted protein that is essential for the activation of a subset of mesodermal markers in the Xenopus embryo. RNA sequencing revealed that many transcriptional targets of Pnhd are shared with those of the FGF pathway. Pnhd activity was accompanied by Erk phosphorylation and required FGF and Nodal but not Wnt signaling. We propose that during gastrulation Pnhd acts in the marginal zone to contribute to mesoderm heterogeneity via an FGF receptor-dependent positive feedback mechanism.
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Affiliation(s)
- Olga Ossipova
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Keiji Itoh
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Aurelian Radu
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jerome Ezan
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Sergei Y Sokol
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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14
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Axis Specification in Zebrafish Is Robust to Cell Mixing and Reveals a Regulation of Pattern Formation by Morphogenesis. Curr Biol 2020; 30:2984-2994.e3. [PMID: 32559447 PMCID: PMC7416079 DOI: 10.1016/j.cub.2020.05.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/01/2020] [Accepted: 05/14/2020] [Indexed: 12/21/2022]
Abstract
A fundamental question in developmental biology is how the early embryo establishes the spatial coordinate system that is later important for the organization of the embryonic body plan. Although we know a lot about the signaling and gene-regulatory networks required for this process, much less is understood about how these can operate to pattern tissues in the context of the extensive cell movements that drive gastrulation. In zebrafish, germ layer specification depends on the inheritance of maternal mRNAs [1, 2, 3], cortical rotation to generate a dorsal pole of β-catenin activity [4, 5, 6, 7, 8], and the release of Nodal signals from the yolk syncytial layer (YSL) [9, 10, 11, 12]. To determine whether germ layer specification is robust to altered cell-to-cell positioning, we separated embryonic cells from the yolk and allowed them to develop as spherical aggregates. These aggregates break symmetry autonomously to form elongated structures with an anterior-posterior pattern. Both forced reaggregation and endogenous cell mixing reveals how robust early axis specification is to spatial disruption of maternal pre-patterning. During these movements, a pole of Nodal signaling emerges that is required for explant elongation via the planar cell polarity (PCP) pathway. Blocking of PCP-dependent elongation disrupts the shaping of opposing poles of BMP and Wnt/TCF activity and the anterior-posterior patterning of neural tissue. These results lead us to suggest that embryo elongation plays a causal role in timing the exposure of cells to changes in BMP and Wnt signal activity during zebrafish gastrulation. Video Abstract
Whole-zebrafish 256-cell stage embryo explants elongate Patterned germ layers are established Mesoderm formation is robust to extensive cell mixing Inhibition of morphogenesis blocks formation of signaling gradients
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15
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Saadaoui M, Rocancourt D, Roussel J, Corson F, Gros J. A tensile ring drives tissue flows to shape the gastrulating amniote embryo. Science 2020; 367:453-458. [PMID: 31974255 DOI: 10.1126/science.aaw1965] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 12/18/2019] [Indexed: 12/21/2022]
Abstract
Tissue morphogenesis is driven by local cellular deformations that are powered by contractile actomyosin networks. How localized forces are transmitted across tissues to shape them at a mesoscopic scale is still unclear. Analyzing gastrulation in entire avian embryos, we show that it is driven by the graded contraction of a large-scale supracellular actomyosin ring at the margin between the embryonic and extraembryonic territories. The propagation of these forces is enabled by a fluid-like response of the epithelial embryonic disk, which depends on cell division. A simple model of fluid motion entrained by a tensile ring quantitatively captures the vortex-like "polonaise" movements that accompany the formation of the primitive streak. The geometry of the early embryo thus arises from the transmission of active forces generated along its boundary.
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Affiliation(s)
- Mehdi Saadaoui
- Department of Developmental and Stem Cell Biology Institut Pasteur, 75724 Paris, Cedex 15, France.,CNRS UMR3738, 75015 Paris, France
| | - Didier Rocancourt
- Department of Developmental and Stem Cell Biology Institut Pasteur, 75724 Paris, Cedex 15, France.,CNRS UMR3738, 75015 Paris, France
| | - Julian Roussel
- Department of Developmental and Stem Cell Biology Institut Pasteur, 75724 Paris, Cedex 15, France.,CNRS UMR3738, 75015 Paris, France
| | - Francis Corson
- Laboratoire de Physique de l'Ecole Normale Supérieure, CNRS, ENS, Université PSL, Sorbonne Université, Université de Paris, 75005 Paris, France.
| | - Jerome Gros
- Department of Developmental and Stem Cell Biology Institut Pasteur, 75724 Paris, Cedex 15, France. .,CNRS UMR3738, 75015 Paris, France
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16
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Lee HC, Lu HC, Turmaine M, Oliveira NMM, Yang Y, De Almeida I, Stern CD. Molecular anatomy of the pre-primitive-streak chick embryo. Open Biol 2020; 10:190299. [PMID: 32102607 PMCID: PMC7058932 DOI: 10.1098/rsob.190299] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 01/13/2020] [Indexed: 12/16/2022] Open
Abstract
The early stages of development of the chick embryo, leading to primitive streak formation (the start of gastrulation), have received renewed attention recently, especially for studies of the mechanisms of large-scale cell movements and those that position the primitive streak in the radial blastodisc. Over the long history of chick embryology, the terminology used to define different regions has been changing, making it difficult to relate studies to each other. To resolve this objectively requires precise definitions of the regions based on anatomical and functional criteria, along with a systematic molecular map that can be compared directly to the functional anatomy. Here, we undertake these tasks. We describe the characteristic cell morphologies (using scanning electron microscopy and immunocytochemistry for cell polarity markers) in different regions and at successive stages. RNAseq was performed for 12 regions of the blastodisc, from which a set of putative regional markers was selected. These were studied in detail by in situ hybridization. Together this provides a comprehensive resource allowing the community to define the regions unambiguously and objectively. In addition to helping with future experimental design and interpretation, this resource will also be useful for evolutionary comparisons between different vertebrate species.
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Affiliation(s)
| | | | | | | | | | | | - Claudio D. Stern
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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17
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Yan Y, Ning G, Li L, Liu J, Yang S, Cao Y, Wang Q. The BMP ligand Pinhead together with Admp supports the robustness of embryonic patterning. SCIENCE ADVANCES 2019; 5:eaau6455. [PMID: 32064309 PMCID: PMC6989304 DOI: 10.1126/sciadv.aau6455] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 04/30/2019] [Accepted: 10/29/2019] [Indexed: 06/10/2023]
Abstract
Vertebrate embryonic dorsoventral axis is robustly stable in the face of variations in bone morphogenetic protein (BMP) signaling. However, the molecular mechanism behind this robustness remains uncharacterized. In this study, we show that zebrafish Pinhead, together with Admp, plays an important compensatory role in ensuring the robustness of axial patterning through fine-tuning of BMP signaling. pinhead encodes a BMP-like ligand expressed in the ventrolateral margin of the early gastrula. Transcription of pinhead and admp is under opposing regulation, where pinhead depletion results in a compensatory increase in admp transcription and vice versa, leading to normal axis formation in pinhead or admp mutants. Expression of pinhead and admp is directly repressed by the BMP/Smad pathway. When BMP signals were inhibited or excessively activated, pinhead/admp expression changed accordingly, allowing for self-regulation. Thus, this study reveals a negative feedback loop between BMP signaling and pinhead/admp that effectively stabilizes embryonic patterning by buffering against fluctuations in BMP signaling.
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Affiliation(s)
- Yifang Yan
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Guozhu Ning
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Linwei Li
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Jie Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Shuyan Yang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu Cao
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiang Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
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18
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19
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Pieper T, Carpaij M, Reinermann J, Surchev L, Viebahn C, Tsikolia N. Matrix-filled microcavities in the emerging avian left-right organizer. Dev Dyn 2019; 249:496-508. [PMID: 31729123 DOI: 10.1002/dvdy.133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/18/2019] [Accepted: 10/18/2019] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Hensen node of the amniote embryo plays a central role in multiple developmental processes, especially in induction and formation of axial organs. In the chick, it is asymmetrical in shape and has recently been considered to represent the left-right organizer. As mechanisms of breaking the initial left-right symmetry of the embryo are still ill-understood, analyzing the node's microarchitecture may provide insights into functional links between symmetry breaking and asymmetric morphology. RESULTS In the course of a light- and electron-microscopic study addressing this issue we discovered novel intercellular matrix-filled cavities in the node of the chick during gastrulation and during early neurulation stages; measuring up to 45 μm, they are surrounded by densely packed cells and filled with nanoscale fibrils, which immunostaining suggests to consist of the basement membrane-related proteins fibronectin and perlecan. The cavities emerge immediately prior to node formation in the epiblast layer adjacent to the tip of the primitive streak and later, with emerging node asymmetry, they are predominantly located in the right part of the node. Almost identical morphological features of microcavities were found in the duck node. CONCLUSIONS We address these cavities as "nodal microcavities" and propose their content to be involved in the function of the avian node by mediating morphogen signaling and storage.
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Affiliation(s)
- Tobias Pieper
- Institute of Anatomy and Embryology, University Medical Center, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Meriam Carpaij
- Institute of Anatomy and Embryology, University Medical Center, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Johanna Reinermann
- Institute of Anatomy and Embryology, University Medical Center, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Lachezar Surchev
- Institute of Anatomy and Embryology, University Medical Center, Georg-August-Universität Göttingen, Göttingen, Germany.,Department of Anatomy, Trakia University Stara Zagora, Stara Zagora, Bulgaria
| | - Christoph Viebahn
- Institute of Anatomy and Embryology, University Medical Center, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Nikoloz Tsikolia
- Institute of Anatomy and Embryology, University Medical Center, Georg-August-Universität Göttingen, Göttingen, Germany
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20
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Rougeot J, Chrispijn ND, Aben M, Elurbe DM, Andralojc KM, Murphy PJ, Jansen PWTC, Vermeulen M, Cairns BR, Kamminga LM. Maintenance of spatial gene expression by Polycomb-mediated repression after formation of a vertebrate body plan. Development 2019; 146:dev.178590. [PMID: 31488564 PMCID: PMC6803366 DOI: 10.1242/dev.178590] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/26/2019] [Indexed: 12/22/2022]
Abstract
Polycomb group (PcG) proteins are transcriptional repressors that are important regulators of cell fate during embryonic development. Among them, Ezh2 is responsible for catalyzing the epigenetic repressive mark H3K27me3 and is essential for animal development. The ability of zebrafish embryos lacking both maternal and zygotic ezh2 to form a normal body plan provides a unique model for comprehensively studying Ezh2 function during early development in vertebrates. By using a multi-omics approach, we found that Ezh2 is required for the deposition of H3K27me3 and is essential for proper recruitment of Polycomb group protein Rnf2. However, despite the complete absence of PcG-associated epigenetic mark and proteins, only minor changes in H3K4me3 deposition and gene and protein expression occur. These changes were mainly due to local dysregulation of transcription factors outside their normal expression boundaries. Altogether, our results in zebrafish show that Polycomb-mediated gene repression is important immediately after the body plan is formed to maintain spatially restricted expression profiles of transcription factors, and we highlight the differences that exist in the timing of PcG protein action between vertebrate species. Summary: Our unique zebrafish model of a maternal and zygotic mutant for the Polycomb group gene ezh2 reveals major conserved and divergent mechanisms in epigenetic gene repression during vertebrate development.
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Affiliation(s)
- Julien Rougeot
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands .,Radboud University Medical Center, Department of Molecular Biology, Nijmegen 6525 GA, The Netherlands
| | - Naomi D Chrispijn
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands
| | - Marco Aben
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands.,Radboud University Medical Center, Department of Molecular Biology, Nijmegen 6525 GA, The Netherlands
| | - Dei M Elurbe
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands.,Radboud University Medical Center, Department of Molecular Biology, Nijmegen 6525 GA, The Netherlands
| | - Karolina M Andralojc
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands
| | - Patrick J Murphy
- Howard Hughes Medical Institute, Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.,Wilmot Cancer Institute, Rochester Center for Biomedical Informatics, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Pascal W T C Jansen
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Oncode Institute, Nijmegen 6525 GA, The Netherlands
| | - Michiel Vermeulen
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Oncode Institute, Nijmegen 6525 GA, The Netherlands
| | - Bradley R Cairns
- Howard Hughes Medical Institute, Department of Oncological Sciences and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Leonie M Kamminga
- Radboud University, Faculty of Science, Department of Molecular Biology, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands .,Radboud University Medical Center, Department of Molecular Biology, Nijmegen 6525 GA, The Netherlands
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21
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Embryonic regeneration by relocalization of the Spemann organizer during twinning in Xenopus. Proc Natl Acad Sci U S A 2018; 115:E4815-E4822. [PMID: 29686106 PMCID: PMC6003488 DOI: 10.1073/pnas.1802749115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The formation of identical twins from a single egg has fascinated developmental biologists for a very long time. Previous work had shown that Xenopus blastulae bisected along the dorsal-ventral (D-V) midline (i.e., the sagittal plane) could generate twins but at very low frequencies. Here, we have improved this method by using an eyelash knife and changing saline solutions, reaching frequencies of twinning of 50% or more. This allowed mechanistic analysis of the twinning process. We unexpectedly observed that the epidermis of the resulting twins was asymmetrically pigmented at the tailbud stage of regenerating tadpoles. This pigment was entirely of maternal (oocyte) origin. Bisecting the embryo generated a large wound, which closed from all directions within 60 minutes, bringing cells normally fated to become Spemann organizer in direct contact with predicted ventral-most cells. Lineage-tracing analyses at the four-cell stage showed that in regenerating embryos midline tissues originated from the dorsal half, while the epidermis was entirely of ventral origin. Labeling of D-V segments at the 16-cell stage showed that the more pigmented epidermis originated from the ventral-most cells, while the less-pigmented epidermis arose from the adjoining ventral segment. This suggested a displacement of the organizer by 90°. Studies with the marker Chordin and phospho-Smad1/5/8 showed that in half embryos a new D-V gradient is intercalated at the site of the missing half. The displacement of self-organizing morphogen gradients uncovered here may help us understand not only twin formation in amphibians, but also rare cases of polyembryony.
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22
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Vermillion KL, Bacher R, Tannenbaum AP, Swanson S, Jiang P, Chu LF, Stewart R, Thomson JA, Vereide DT. Spatial patterns of gene expression are unveiled in the chick primitive streak by ordering single-cell transcriptomes. Dev Biol 2018; 439:30-41. [PMID: 29678445 DOI: 10.1016/j.ydbio.2018.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/11/2018] [Accepted: 04/11/2018] [Indexed: 01/07/2023]
Abstract
During vertebrate development, progenitor cells give rise to tissues and organs through a complex choreography that commences at gastrulation. A hallmark event of gastrulation is the formation of the primitive streak, a linear assembly of cells along the anterior-posterior (AP) axis of the developing organism. To examine the primitive streak at a single-cell resolution, we measured the transcriptomes of individual chick cells from the streak or the surrounding tissue (the rest of the area pellucida) in Hamburger-Hamilton stage 4 embryos. The single-cell transcriptomes were then ordered by the statistical method Wave-Crest to deduce both the relative position along the AP axis and the prospective lineage of single cells. The ordered transcriptomes reveal intricate patterns of gene expression along the primitive streak.
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Affiliation(s)
| | - Rhonda Bacher
- Department of Biostatistics, University of Florida, Gainesville, FL 32611, USA
| | | | - Scott Swanson
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Peng Jiang
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Li-Fang Chu
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - Ron Stewart
- Morgridge Institute for Research, Madison, WI 53715, USA
| | - James A Thomson
- Morgridge Institute for Research, Madison, WI 53715, USA; Department of Cell&Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53706, USA; Department of Molecular, Cellular,&Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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23
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Kremnyov S, Henningfeld K, Viebahn C, Tsikolia N. Divergent axial morphogenesis and early shh expression in vertebrate prospective floor plate. EvoDevo 2018; 9:4. [PMID: 29423139 PMCID: PMC5791209 DOI: 10.1186/s13227-017-0090-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 12/18/2017] [Indexed: 11/10/2022] Open
Abstract
Background The notochord has organizer properties and is required for floor plate induction and dorsoventral patterning of the neural tube. This activity has been attributed to sonic hedgehog (shh) signaling, which originates in the notochord, forms a gradient, and autoinduces shh expression in the floor plate. However, reported data are inconsistent and the spatiotemporal development of the relevant shh expression domains has not been studied in detail. We therefore studied the expression dynamics of shh in rabbit, chicken and Xenopus laevis embryos (as well as indian hedgehog and desert hedgehog as possible alternative functional candidates in the chicken). Results Our analysis reveals a markedly divergent pattern within these vertebrates: whereas in the rabbit shh is first expressed in the notochord and its floor plate domain is then induced during subsequent somitogenesis stages, in the chick embryo shh is expressed in the prospective neuroectoderm prior to the notochord formation and, interestingly, prior to mesoderm immigration. Neither indian hedgehog nor desert hedgehog are expressed in these midline structures although mRNA of both genes was detected in other structures of the early chick embryo. In X. laevis, shh is expressed at the beginning of gastrulation in a distinct area dorsal to the dorsal blastopore lip and adjacent to the prospective neuroectoderm, whereas the floor plate expresses shh at the end of gastrulation. Conclusions While shh expression patterns in rabbit and X. laevis embryos are roughly compatible with the classical view of "ventral to dorsal induction" of the floor plate, the early shh expression in the chick floor plate challenges this model. Intriguingly, this alternative sequence of domain induction is related to the asymmetrical morphogenesis of the primitive node and other axial organs in the chick. Our results indicate that the floor plate in X. laevis and chick embryos may be initially induced by planar interaction within the ectoderm or epiblast. Furthermore, we propose that the mode of the floor plate induction adapts to the variant topography of interacting tissues during gastrulation and notochord formation and thereby reveals evolutionary plasticity of early embryonic induction.
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Affiliation(s)
- Stanislav Kremnyov
- 1Department of Embryology, Faculty of Biology, Lomonosov State University Moscow, Leninskie Gory, 1, Builung 12, Moscow, Russia 119234.,2Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Vavilova Str., 26, Moscow, Russia 119991
| | - Kristine Henningfeld
- 3Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Institute of Developmental Biochemistry, University Medical Center Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Christoph Viebahn
- 4Institute of Anatomy and Embryology, University Medical Center Göttingen, Kreuzbergring 36, 37085 Göttingen, Germany
| | - Nikoloz Tsikolia
- 4Institute of Anatomy and Embryology, University Medical Center Göttingen, Kreuzbergring 36, 37085 Göttingen, Germany
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24
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Leibovich A, Kot-Leibovich H, Ben-Zvi D, Fainsod A. ADMP controls the size of Spemann's organizer through a network of self-regulating expansion-restriction signals. BMC Biol 2018; 16:13. [PMID: 29357852 PMCID: PMC5778663 DOI: 10.1186/s12915-018-0483-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 01/08/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The bone morphogenetic protein (BMP) signaling gradient is central for dorsoventral patterning in amphibian embryos. This gradient is established through the interaction of several BMPs and BMP antagonists and modulators, some secreted by Spemann's organizer, a cluster of cells coordinating embryonic development. Anti-dorsalizing morphogenetic protein (ADMP), a BMP-like transforming growth factor beta ligand, negatively affects the formation of the organizer, although it is robustly expressed within the organizer itself. Previously, we proposed that this apparent discrepancy may be important for the ability of ADMP to scale the BMP gradient with embryo size, but how this is achieved is unclear. RESULTS Here we report that ADMP acts in the establishment of the organizer via temporally and mechanistically distinct signals. At the onset of gastrulation, ADMP is required to establish normal organizer-specific gene expression domains, thus displaying a dorsal, organizer-promoting function. The organizer-restricting, BMP-like function of ADMP becomes apparent slightly later, from mid-gastrula. The organizer-promoting signal of ADMP is mediated by the activin A type I receptor, ACVR1 (also known as activin receptor-like kinase-2, ALK2). ALK2 is expressed in the organizer and is required for organizer establishment. The anti-organizer function of ADMP is mediated by ACVRL1 (ALK1), a putative ADMP receptor expressed in the lateral regions flanking the organizer that blocks expansion of the organizer. Truncated ALK1 prevents the organizer-restricting effects of ADMP overexpression, suggesting a ligand-receptor interaction. We also present a mathematical model of the regulatory network controlling the size of the organizer. CONCLUSIONS We show that the opposed, organizer-promoting and organizer-restricting roles of ADMP are mediated by different receptors. A self-regulating network is proposed in which ADMP functions early through ALK2 to expand its own expression domain, the organizer, and later functions through ALK1 to restrict this domain. These effects are dependent on ADMP concentration, timing, and the spatial localization of the two receptors. This self-regulating temporal switch may control the size of the organizer and the genes expressed within in response to genetic and external stimuli during gastrulation.
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Affiliation(s)
- Avi Leibovich
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel
| | - Hadas Kot-Leibovich
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel
| | - Danny Ben-Zvi
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel
| | - Abraham Fainsod
- Department of Developmental Biology and Cancer Research, Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, 91120, Israel.
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25
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Steventon B, Martinez Arias A. Evo-engineering and the cellular and molecular origins of the vertebrate spinal cord. Dev Biol 2017; 432:3-13. [DOI: 10.1016/j.ydbio.2017.01.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/03/2017] [Accepted: 01/31/2017] [Indexed: 12/31/2022]
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26
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Growth and Morphogenesis during Early Heart Development in Amniotes. J Cardiovasc Dev Dis 2017; 4:jcdd4040020. [PMID: 29367549 PMCID: PMC5753121 DOI: 10.3390/jcdd4040020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 11/17/2017] [Accepted: 11/17/2017] [Indexed: 11/17/2022] Open
Abstract
In this review, we will focus on the growth and morphogenesis of the developing heart, an aspect of cardiovascular development to which Antoon Moorman and colleagues have extensively contributed. Over the last decades, genetic studies and characterization of regionally regulated gene programs have provided abundant novel insights into heart development essential to understand the basis of congenital heart disease. Heart morphogenesis, however, is inherently a complex and dynamic three-dimensional process and we are far from understanding its cellular basis. Here, we discuss recent advances in studying heart morphogenesis and regionalization under the light of the pioneering work of Moorman and colleagues, which allowed the reinterpretation of regional gene expression patterns under a new morphogenetic framework. Two aspects of early heart formation will be discussed in particular: (1) the initial formation of the heart tube and (2) the formation of the cardiac chambers by the ballooning process. Finally, we emphasize that in addition to analyses based on fixed samples, new approaches including clonal analysis, single-cell sequencing, live-imaging and quantitative analysis of the data generated will likely lead to novel insights in understanding early heart tube regionalization and morphogenesis in the near future.
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27
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Tseng WC, Munisha M, Gutierrez JB, Dougan ST. Establishment of the Vertebrate Germ Layers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:307-381. [PMID: 27975275 DOI: 10.1007/978-3-319-46095-6_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The process of germ layer formation is a universal feature of animal development. The germ layers separate the cells that produce the internal organs and tissues from those that produce the nervous system and outer tissues. Their discovery in the early nineteenth century transformed embryology from a purely descriptive field into a rigorous scientific discipline, in which hypotheses could be tested by observation and experimentation. By systematically addressing the questions of how the germ layers are formed and how they generate overall body plan, scientists have made fundamental contributions to the fields of evolution, cell signaling, morphogenesis, and stem cell biology. At each step, this work was advanced by the development of innovative methods of observing cell behavior in vivo and in culture. Here, we take an historical approach to describe our current understanding of vertebrate germ layer formation as it relates to the long-standing questions of developmental biology. By comparing how germ layers form in distantly related vertebrate species, we find that highly conserved molecular pathways can be adapted to perform the same function in dramatically different embryonic environments.
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Affiliation(s)
- Wei-Chia Tseng
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Mumingjiang Munisha
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Juan B Gutierrez
- Department of Mathematics, University of Georgia, Athens, GA, 30602, USA.,Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA
| | - Scott T Dougan
- Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA.
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28
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Houston DW. Vertebrate Axial Patterning: From Egg to Asymmetry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:209-306. [PMID: 27975274 PMCID: PMC6550305 DOI: 10.1007/978-3-319-46095-6_6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The emergence of the bilateral embryonic body axis from a symmetrical egg has been a long-standing question in developmental biology. Historical and modern experiments point to an initial symmetry-breaking event leading to localized Wnt and Nodal growth factor signaling and subsequent induction and formation of a self-regulating dorsal "organizer." This organizer forms at the site of notochord cell internalization and expresses primarily Bone Morphogenetic Protein (BMP) growth factor antagonists that establish a spatiotemporal gradient of BMP signaling across the embryo, directing initial cell differentiation and morphogenesis. Although the basics of this model have been known for some time, many of the molecular and cellular details have only recently been elucidated and the extent that these events remain conserved throughout vertebrate evolution remains unclear. This chapter summarizes historical perspectives as well as recent molecular and genetic advances regarding: (1) the mechanisms that regulate symmetry-breaking in the vertebrate egg and early embryo, (2) the pathways that are activated by these events, in particular the Wnt pathway, and the role of these pathways in the formation and function of the organizer, and (3) how these pathways also mediate anteroposterior patterning and axial morphogenesis. Emphasis is placed on comparative aspects of the egg-to-embryo transition across vertebrates and their evolution. The future prospects for work regarding self-organization and gene regulatory networks in the context of early axis formation are also discussed.
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Affiliation(s)
- Douglas W Houston
- Department of Biology, The University of Iowa, 257 BB, Iowa City, IA, 52242, USA.
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29
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Anderson C, Khan MAF, Wong F, Solovieva T, Oliveira NMM, Baldock RA, Tickle C, Burt DW, Stern CD. A strategy to discover new organizers identifies a putative heart organizer. Nat Commun 2016; 7:12656. [PMID: 27557800 DOI: 10.1038/ncomms12656] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/19/2016] [Indexed: 11/09/2022] Open
Abstract
Organizers are regions of the embryo that can both induce new fates and impart pattern on other regions. So far, surprisingly few organizers have been discovered, considering the number of patterned tissue types generated during development. This may be because their discovery has relied on transplantation and ablation experiments. Here we describe a new approach, using chick embryos, to discover organizers based on a common gene expression signature, and use it to uncover the anterior intestinal portal (AIP) endoderm as a putative heart organizer. We show that the AIP can induce cardiac identity from non-cardiac mesoderm and that it can pattern this by specifying ventricular and suppressing atrial regional identity. We also uncover some of the signals responsible. The method holds promise as a tool to discover other novel organizers acting during development.
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Affiliation(s)
- Claire Anderson
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Mohsin A F Khan
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Frances Wong
- Department of Genomics and Genetics, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG Scotland, UK
| | - Tatiana Solovieva
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Nidia M M Oliveira
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Richard A Baldock
- Biomedical Systems Analysis Section, MRC Human Genetics Unit, IGMM, University of Edinburgh, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Cheryll Tickle
- Department of Biology &Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Dave W Burt
- Department of Genomics and Genetics, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG Scotland, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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Abstract
The discovery of the transforming growth factor β (TGF-β) family ligands and the realization that their bioactivities need to be tightly controlled temporally and spatially led to intensive research that has identified a multitude of extracellular modulators of TGF-β family ligands, uncovered their functions in developmental and pathophysiological processes, defined the mechanisms of their activities, and explored potential modulator-based therapeutic applications in treating human diseases. These studies revealed a diverse repertoire of extracellular and membrane-associated molecules that are capable of modulating TGF-β family signals via control of ligand availability, processing, ligand-receptor interaction, and receptor activation. These molecules include not only soluble ligand-binding proteins that were conventionally considered as agonists and antagonists of TGF-β family of growth factors, but also extracellular matrix (ECM) proteins and proteoglycans that can serve as "sink" and control storage and release of both the TGF-β family ligands and their regulators. This extensive network of soluble and ECM modulators helps to ensure dynamic and cell-specific control of TGF-β family signals. This article reviews our knowledge of extracellular modulation of TGF-β growth factors by diverse proteins and their molecular mechanisms to regulate TGF-β family signaling.
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Affiliation(s)
- Chenbei Chang
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294
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31
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Sieiro D, Rios AC, Hirst CE, Marcelle C. Cytoplasmic NOTCH and membrane-derived β-catenin link cell fate choice to epithelial-mesenchymal transition during myogenesis. eLife 2016; 5. [PMID: 27218451 PMCID: PMC4917337 DOI: 10.7554/elife.14847] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 05/23/2016] [Indexed: 11/13/2022] Open
Abstract
How cells in the embryo coordinate epithelial plasticity with cell fate decision in a fast changing cellular environment is largely unknown. In chick embryos, skeletal muscle formation is initiated by migrating Delta1-expressing neural crest cells that trigger NOTCH signaling and myogenesis in selected epithelial somite progenitor cells, which rapidly translocate into the nascent muscle to differentiate. Here, we uncovered at the heart of this response a signaling module encompassing NOTCH, GSK-3β, SNAI1 and β-catenin. Independent of its transcriptional function, NOTCH profoundly inhibits GSK-3β activity. As a result SNAI1 is stabilized, triggering an epithelial to mesenchymal transition. This allows the recruitment of β-catenin from the membrane, which acts as a transcriptional co-factor to activate myogenesis, independently of WNT ligand. Our results intimately associate the initiation of myogenesis to a change in cell adhesion and may reveal a general principle for coupling cell fate changes to EMT in many developmental and pathological processes. DOI:http://dx.doi.org/10.7554/eLife.14847.001
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Affiliation(s)
- Daniel Sieiro
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia.,Institut NeuroMyoGene, University Lyon 1, CNRS UMR 5310, INSERM U 1217, Villeurbanne, France
| | - Anne C Rios
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
| | - Claire E Hirst
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia
| | - Christophe Marcelle
- Australian Regenerative Medicine Institute, Monash University, Clayton, Australia.,Institut NeuroMyoGene, University Lyon 1, CNRS UMR 5310, INSERM U 1217, Villeurbanne, France
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32
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Meinhardt H. Dorsoventral patterning by the Chordin-BMP pathway: a unified model from a pattern-formation perspective for drosophila, vertebrates, sea urchins and nematostella. Dev Biol 2015; 405:137-48. [DOI: 10.1016/j.ydbio.2015.05.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/14/2015] [Indexed: 01/15/2023]
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33
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Stern CD, Piatkowska AM. Multiple roles of timing in somite formation. Semin Cell Dev Biol 2015; 42:134-9. [PMID: 26116228 DOI: 10.1016/j.semcdb.2015.06.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 06/15/2015] [Indexed: 12/11/2022]
Abstract
During development, vertebrate embryos produce serially repeated elements, the somites, on each side of the midline. These generate the vertebral column, skeletal musculature and dermis. They form sequentially, one pair at a time, from mesenchymal tissue near the tail. Somite development is a complex process. The embryo must control the number, size, and timing of somite formation, their subdivision into functional regions along three axes, regional identity such that somites develop in a region-specific way, and interactions with neighbouring tissues that coordinate them with nearby structures. Here we discuss many timing-related mechanisms that contribute to set up the spatial pattern.
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Affiliation(s)
- Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
| | - Agnieszka M Piatkowska
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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34
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Mendes R, Martins G, Cristovão A, Saúde L. N-Cadherin Locks Left-Right Asymmetry by Ending the Leftward Movement of Hensen’s Node Cells. Dev Cell 2014; 30:353-60. [DOI: 10.1016/j.devcel.2014.06.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 05/17/2014] [Accepted: 06/12/2014] [Indexed: 01/29/2023]
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35
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Voiculescu O, Bodenstein L, Lau IJ, Stern CD. Local cell interactions and self-amplifying individual cell ingression drive amniote gastrulation. eLife 2014; 3:e01817. [PMID: 24850665 PMCID: PMC4029171 DOI: 10.7554/elife.01817] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Gastrulation generates three layers of cells (ectoderm, mesoderm, endoderm) from a single sheet, while large scale cell movements occur across the entire embryo. In amniote (reptiles, birds, mammals) embryos, the deep layers arise by epithelial-to-mesenchymal transition (EMT) at a morphologically stable midline structure, the primitive streak (PS). We know very little about how these events are controlled or how the PS is maintained despite its continuously changing cellular composition. Using the chick, we show that isolated EMT events and ingression of individual cells start well before gastrulation. A Nodal-dependent ‘community effect’ then concentrates and amplifies EMT by positive feedback to form the PS as a zone of massive cell ingression. Computer simulations show that a combination of local cell interactions (EMT and cell intercalation) is sufficient to explain PS formation and the associated complex movements globally across a large epithelial sheet, without the need to invoke long-range signalling. DOI:http://dx.doi.org/10.7554/eLife.01817.001 A key process during the development of an embryo involves a single layer of cells reorganizing into three ‘germ layers’: the ectoderm, which becomes the skin and nervous system; the mesoderm, which gives rise to the skeleton, muscles and the circulatory and urinogenital systems, and the endoderm, which gives rise to the lining of the gut and associated organs. The process of forming these three layers is known as gastrulation. To date most experiments on gastrulation in vertebrates have been performed on frog embryos. However, the embryos of amniotes, the group of ‘higher’ vertebrates that comprises reptiles, birds and mammals, differ from those of frogs in a number of ways. Now Voiculescu et al. have used a combination of experimental and computational techniques to shed new light on gastrulation in chick embryos. Just prior to gastrulation, the cells of the amniote embryo are arranged in a flat disk, one cell thick, called the epiblast. The cells of the epiblast then move to form the mesoderm and endoderm (in a process called epithelial-to-mesenchymal transition). These cell movements also lead to the formation of a structure called the primitive streak that establishes the left-right symmetry of the organism, and also defines the midline of the body. Now Voiculescu et al. have shown that the epithelial-to-mesenchymal transition starts before the primitive streak appears, and that two main processes drive gastrulation. One involves cells inserting themselves between other cells at the midline of the epiblast, which causes a double whorl-like movement within the plane of the epiblast. At the same time small numbers of cells leave the epiblast, and as these cells accumulate under the epiblast, they initiate a positive feedback effect by which they encourage more cells to leave the epiblast. Voiculescu et al. found that this ‘community effect’ involves signalling by a protein called Nodal. This protein effectively amplifies the epithelial-to-mesenchymal transition and leads to the appearance of the primitive streak at the midline. Using computational modelling, Voiculescu et al. argue that the movements of gastrulation can be explained entirely based on local interactions between cells, without the need for cells to send signals over long distances to guide cell movements, as had been generally believed. DOI:http://dx.doi.org/10.7554/eLife.01817.002
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Affiliation(s)
- Octavian Voiculescu
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Lawrence Bodenstein
- Division of Pediatric Surgery, Morgan Stanley Children's Hospital of New York-Presbyterian, New York, United States Department of Surgery, College of Physicians and Surgeons, Columbia University, New York, United States
| | - I-Jun Lau
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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36
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Abstract
Body axis elongation and segmentation are major morphogenetic events that take place concomitantly during vertebrate embryonic development. Establishment of the final body plan requires tight coordination between these two key processes. In this review, we detail the cellular and molecular as well as the physical processes underlying body axis formation and patterning. We discuss how formation of the anterior region of the body axis differs from that of the posterior region. We describe the developmental mechanism of segmentation and the regulation of body length and segment numbers. We focus mainly on the chicken embryo as a model system. Its accessibility and relatively flat structure allow high-quality time-lapse imaging experiments, which makes it one of the reference models used to study morphogenesis. Additionally, we illustrate conservation and divergence of specific developmental mechanisms by discussing findings in other major embryonic model systems, such as mice, frogs, and zebrafish.
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Affiliation(s)
- Bertrand Bénazéraf
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS (UMR 7104), Université de Strasbourg, Illkirch F-67400, France;
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37
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Fleming BM, Yelin R, James RG, Schultheiss TM. A role for Vg1/Nodal signaling in specification of the intermediate mesoderm. Development 2013; 140:1819-29. [PMID: 23533180 PMCID: PMC3621495 DOI: 10.1242/dev.093740] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2013] [Indexed: 11/20/2022]
Abstract
The intermediate mesoderm (IM) is the embryonic source of all kidney tissue in vertebrates. The factors that regulate the formation of the IM are not yet well understood. Through investigations in the chick embryo, the current study identifies and characterizes Vg1/Nodal signaling (henceforth referred to as 'Nodal-like signaling') as a novel regulator of IM formation. Excess Nodal-like signaling at gastrulation stages resulted in expansion of the IM at the expense of the adjacent paraxial mesoderm, whereas inhibition of Nodal-like signaling caused repression of IM gene expression. IM formation was sensitive to levels of the Nodal-like pathway co-receptor Cripto and was inhibited by a truncated form of the secreted molecule cerberus, which specifically blocks Nodal, indicating that the observed effects are specific to the Nodal-like branch of the TGFβ signaling pathway. The IM-promoting effects of Nodal-like signaling were distinct from the known effects of this pathway on mesoderm formation and left-right patterning, a finding that can be attributed to specific time windows for the activities of these Nodal-like functions. Finally, a link was observed between Nodal-like and BMP signaling in the induction of IM. Activation of IM genes by Nodal-like signaling required an active BMP signaling pathway, and Nodal-like signals induced phosphorylation of Smad1/5/8, which is normally associated with activation of BMP signaling pathways. We postulate that Nodal-like signaling regulates IM formation by modulating the IM-inducing effects of BMP signaling.
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Affiliation(s)
- Britannia M. Fleming
- Department of Anatomy and Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ronit Yelin
- Department of Anatomy and Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Richard G. James
- Department of Pharmacology, University of Washington, Seattle, WA, 98195, USA
| | - Thomas M. Schultheiss
- Department of Anatomy and Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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38
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Imai KS, Daido Y, Kusakabe TG, Satou Y. Cis-acting transcriptional repression establishes a sharp boundary in chordate embryos. Science 2012; 337:964-7. [PMID: 22923581 DOI: 10.1126/science.1222488] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The function of bone morphogenetic protein (BMP) signaling in dorsoventral (DV) patterning of animal embryos is conserved among Bilateria. In vertebrates, the BMP ligand antidorsalizing morphogenetic protein (Admp) is expressed dorsally and moves to the opposite side to specify the ventral fate. Here, we show that Pinhead is an antagonist specific for Admp with a role in establishing the DV axis of the trunk epidermis in embryos of the ascidian Ciona intestinalis. Pinhead and Admp exist in tandem in the genomes of various animals from arthropods to vertebrates. This genomic configuration is important for mutually exclusive expression of these genes, because Pinhead transcription directly disturbs the action of the Admp enhancer. Our data suggest that this dual negative regulatory mechanism is widely conserved in animals.
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Affiliation(s)
- Kaoru S Imai
- Department of Biodiversity, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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39
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Shin D, Weidinger G, Moon RT, Stainier DYR. Intrinsic and extrinsic modifiers of the regulative capacity of the developing liver. Mech Dev 2012; 128:525-35. [PMID: 22313811 DOI: 10.1016/j.mod.2012.01.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 01/23/2012] [Indexed: 10/14/2022]
Abstract
Zebrafish wnt2bb mutants initially fail to form a liver, but surprisingly the liver eventually forms in a majority of these embryos which then develop into fertile adults. This unexpected result raised the possibility that identifying the mechanisms of liver formation in wnt2bb mutants could provide insights into the poorly understood yet general principle of regulative development, a process by which some cells can change fate in order to compensate for a deficiency. Here, we identify two factors that underlie the regulative capacity of endodermal tissues: an intrinsic factor, Sox32, a transcription factor of the SoxF subfamily, and an extrinsic factor, Fgf10a. sox32 is expressed in the extrahepatic duct primordium which is not affected in wnt2bb mutants. Blocking Sox32 function prevented liver formation in most wnt2bb mutants. fgf10a, which is expressed in the mesenchyme surrounding non-hepatic endodermal cells, negatively impacts the regulative capacity of endodermal tissues. In Wnt/β-catenin signaling deficient embryos, in which the liver completely fails to form, the repression of Fgf10a function allowed liver formation. Altogether, these studies reveal that there is more than one way to form a liver, and provide molecular insights into the phenomenon of tissue plasticity.
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Affiliation(s)
- Donghun Shin
- Department of Biochemistry and Biophysics, Programs in Developmental and Stem Cell Biology, Genetics and Human Genetics, Institute for Regeneration Medicine, Diabetes Center and Liver Center, University of California, San Francisco, CA 94158, USA.
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40
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Lemke S, Antonopoulos DA, Meyer F, Domanus MH, Schmidt-Ott U. BMP signaling components in embryonic transcriptomes of the hover fly Episyrphus balteatus (Syrphidae). BMC Genomics 2011; 12:278. [PMID: 21627820 PMCID: PMC3224130 DOI: 10.1186/1471-2164-12-278] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 05/31/2011] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND In animals, signaling of Bone Morphogenetic Proteins (BMPs) is essential for dorsoventral (DV) patterning of the embryo, but how BMP signaling evolved with changes in embryonic DV differentiation is largely unclear. Based on the extensive knowledge of BMP signaling in Drosophila melanogaster, the morphological diversity of extraembryonic tissues in different fly species provides a comparative system to address this question. The closest relatives of D. melanogaster with clearly distinct DV differentiation are hover flies (Diptera: Syrphidae). The syrphid Episyrphus balteatus is a commercial bio-agent against aphids and has been established as a model organism for developmental studies and chemical ecology. The dorsal blastoderm of E. balteatus gives rise to two extraembryonic tissues (serosa and amnion), whereas in D. melanogaster, the dorsal blastoderm differentiates into a single extraembryonic epithelium (amnioserosa). Recent studies indicate that several BMP signaling components of D. melanogaster, including the BMP ligand Screw (Scw) and other extracellular regulators, evolved in the dipteran lineage through gene duplication and functional divergence. These findings raise the question of whether the complement of BMP signaling components changed with the origin of the amnioserosa. RESULTS To search for BMP signaling components in E. balteatus, we generated and analyzed transcriptomes of freshly laid eggs (0-30 minutes) and late blastoderm to early germband extension stages (3-6 hours) using Roche/454 sequencing. We identified putative E. balteatus orthologues of 43% of all annotated D. melanogaster genes, including the genes of all BMP ligands and other BMP signaling components. CONCLUSION The diversification of several BMP signaling components in the dipteran linage of D. melanogaster preceded the origin of the amnioserosa.[Transcriptome sequence data from this study have been deposited at the NCBI Sequence Read Archive (SRP005289); individually assembled sequences have been deposited at GenBank (JN006969-JN006986).].
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Affiliation(s)
- Steffen Lemke
- University of Chicago, Dept. of Organismal Biology and Anatomy, CLSC 921B, 920 E. 58th Street, Chicago, IL 60637, USA
- Current Address: University of Heidelberg, Centre for Organismal Studies, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
| | - Dionysios A Antonopoulos
- Argonne National Laboratory, Institute for Genomics & Systems Biology, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Folker Meyer
- Argonne National Laboratory, Institute for Genomics & Systems Biology, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Marc H Domanus
- Argonne National Laboratory, Institute for Genomics & Systems Biology, 9700 S. Cass Avenue, Argonne, IL 60439, USA
| | - Urs Schmidt-Ott
- University of Chicago, Dept. of Organismal Biology and Anatomy, CLSC 921B, 920 E. 58th Street, Chicago, IL 60637, USA
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41
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Rios AC, Serralbo O, Salgado D, Marcelle C. Neural crest regulates myogenesis through the transient activation of NOTCH. Nature 2011; 473:532-5. [PMID: 21572437 DOI: 10.1038/nature09970] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 02/24/2011] [Indexed: 11/09/2022]
Abstract
How dynamic signalling and extensive tissue rearrangements interact to generate complex patterns and shapes during embryogenesis is poorly understood. Here we characterize the signalling events taking place during early morphogenesis of chick skeletal muscles. We show that muscle progenitors present in somites require the transient activation of NOTCH signalling to undergo terminal differentiation. The NOTCH ligand Delta1 is expressed in a mosaic pattern in neural crest cells that migrate past the somites. Gain and loss of Delta1 function in neural crest modifies NOTCH signalling in somites, which results in delayed or premature myogenesis. Our results indicate that the neural crest regulates early muscle formation by a unique mechanism that relies on the migration of Delta1-expressing neural crest cells to trigger the transient activation of NOTCH signalling in selected muscle progenitors. This dynamic signalling guarantees a balanced and progressive differentiation of the muscle progenitor pool.
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Affiliation(s)
- Anne C Rios
- EMBL Australia, Australian Regenerative Medicine Institute, Monash University, Building 75, Clayton, Victoria 3800, Australia
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42
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Sharon N, Mor I, Golan-lev T, Fainsod A, Benvenisty N. Molecular and Functional Characterizations of Gastrula Organizer Cells Derived from Human Embryonic Stem Cells. Stem Cells 2011; 29:600-8. [DOI: 10.1002/stem.621] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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43
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Gaviño MA, Reddien PW. A Bmp/Admp regulatory circuit controls maintenance and regeneration of dorsal-ventral polarity in planarians. Curr Biol 2011; 21:294-9. [PMID: 21295483 DOI: 10.1016/j.cub.2011.01.017] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 11/19/2010] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
Animal embryos have diverse anatomy and vary greatly in size. It is therefore remarkable that a common signaling pathway, BMP signaling, controls development of the dorsoventral (DV) axis throughout the Bilateria. In vertebrates, spatially opposed expression of the BMP family proteins Bmp4 and Admp (antidorsalizing morphogenetic protein) can promote restoration of DV pattern following tissue removal. bmp4 orthologs have been identified in all three groups of the Bilateria (deuterostomes, ecdysozoans, and lophotrochozoans). By contrast, the absence of admp orthologs in ecdysozoans such as Drosophila and C. elegans has suggested that a regulatory circuit of oppositely expressed bmp4 and admp genes represents a deuterostome-specific innovation. Here we describe the existence of spatially opposed bmp and admp expression in a protostome. An admp ortholog (Smed-admp) is expressed ventrally and laterally in adult Schmidtea mediterranea planarians, opposing the dorsal-pole expression of Smed-bmp4. Smed-admp is required for regeneration following parasagittal amputation. Furthermore, Smed-admp promotes Smed-bmp4 expression and Smed-bmp4 inhibits Smed-admp expression, generating a regulatory circuit that buffers against perturbations of Bmp signaling. These results suggest that a Bmp/Admp regulatory circuit is a central feature of the Bilateria, used broadly for the establishment, maintenance, and regeneration of the DV axis.
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Affiliation(s)
- Michael A Gaviño
- Howard Hughes Medical Institute, Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, 9 Cambridge Center, Cambridge, MA 02142, USA
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45
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Hassoun R, Schwartz P, Rath D, Viebahn C, Männer J. Germ layer differentiation during early hindgut and cloaca formation in rabbit and pig embryos. J Anat 2010; 217:665-78. [PMID: 20874819 DOI: 10.1111/j.1469-7580.2010.01303.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Relative to recent advances in understanding molecular requirements for endoderm differentiation, the dynamics of germ layer morphology and the topographical distribution of molecular factors involved in endoderm formation at the caudal pole of the embryonic disc are still poorly defined. To discover common principles of mammalian germ layer development, pig and rabbit embryos at late gastrulation and early neurulation stages were analysed as species with a human-like embryonic disc morphology, using correlative light and electron microscopy. Close intercellular contact but no direct structural evidence of endoderm formation such as mesenchymal-epithelial transition between posterior primitive streak mesoderm and the emerging posterior endoderm were found. However, a two-step process closely related to posterior germ layer differentiation emerged for the formation of the cloacal membrane: (i) a continuous mesoderm layer and numerous patches of electron-dense flocculent extracellular matrix mark the prospective region of cloacal membrane formation; and (ii) mesoderm cells and all extracellular matrix including the basement membrane are lost locally and close intercellular contact between the endoderm and ectoderm is established. The latter process involves single cells at first and then gradually spreads to form a longitudinally oriented seam-like cloacal membrane. These gradual changes were found from gastrulation to early somite stages in the pig, whereas they were found from early somite to mid-somite stages in the rabbit; in both species cloacal membrane formation is complete prior to secondary neurulation. The results highlight the structural requirements for endoderm formation during development of the hindgut and suggest new mechanisms for the pathogenesis of common urogenital and anorectal malformations.
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Affiliation(s)
- Romia Hassoun
- Department of Anatomy and Embryology, Göttingen University, Göttingen, Germany
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46
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Alev C, Wu Y, Kasukawa T, Jakt LM, Ueda HR, Sheng G. Transcriptomic landscape of the primitive streak. Development 2010; 137:2863-74. [PMID: 20667916 DOI: 10.1242/dev.053462] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In birds and mammals, all mesoderm cells are generated from the primitive streak. Nascent mesoderm cells contain unique dorsoventral (D/V) identities according to their relative ingression position along the streak. Molecular mechanisms controlling this initial phase of mesoderm diversification are not well understood. Using the chick model, we generated high-quality transcriptomic datasets of different streak regions and analyzed their molecular heterogeneity. Fifteen percent of expressed genes exhibit differential expression levels, as represented by two major groups (dorsal to ventral and ventral to dorsal). A complete set of transcription factors and many novel genes with strong and region-specific expression were uncovered. Core components of BMP, Wnt and FGF pathways showed little regional difference, whereas their positive and negative regulators exhibited both dorsal-to-ventral and ventral-to-dorsal gradients, suggesting that robust D/V positional information is generated by fine-tuned regulation of key signaling pathways at multiple levels. Overall, our study provides a comprehensive molecular resource for understanding mesoderm diversification in vivo and targeted mesoderm lineage differentiation in vitro.
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Affiliation(s)
- Cantas Alev
- Laboratory for Early Embryogenesis, RIKEN Center for Developmental Biology, Kobe, Hyogo, Japan
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47
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Niehrs C. On growth and form: a Cartesian coordinate system of Wnt and BMP signaling specifies bilaterian body axes. Development 2010; 137:845-57. [DOI: 10.1242/dev.039651] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The regulation of body axis specification in the common ancestor of bilaterians remains controversial. BMP signaling appears to be an ancient program for patterning the secondary, or dorsoventral, body axis, but any such program for the primary, or anteroposterior, body axis is debated. Recent work in invertebrates indicates that posterior Wnt/β-catenin signaling is such a mechanism and that it evolutionarily predates the cnidarian-bilaterian split. Here, I argue that a Cartesian coordinate system of positional information set up by gradients of perpendicular Wnt and BMP signaling is conserved in bilaterians, orchestrates body axis patterning and contributes to both the relative invariance and diversity of body forms.
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Affiliation(s)
- Christof Niehrs
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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48
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Wilson V, Olivera-Martinez I, Storey KG. Stem cells, signals and vertebrate body axis extension. Development 2009; 136:1591-604. [PMID: 19395637 DOI: 10.1242/dev.021246] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The progressive generation of chick and mouse axial tissues - the spinal cord, skeleton and musculature of the body - has long been proposed to depend on the activity of multipotent stem cells. Here, we evaluate evidence for the existence and multipotency of axial stem cells. We show that although the data strongly support their existence, there is little definitive information about their multipotency or extent of contribution to the axis. We also review the location and molecular characteristics of these putative stem cells, along with their evolutionary conservation in vertebrates and the signalling mechanisms that regulate and arrest axis extension.
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Barkai N, Ben-Zvi D. 'Big frog, small frog'--maintaining proportions in embryonic development: delivered on 2 July 2008 at the 33rd FEBS Congress in Athens, Greece. FEBS J 2009; 276:1196-207. [PMID: 19175672 DOI: 10.1111/j.1742-4658.2008.06854.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We discuss mechanisms that enable the scaling of pattern with size during the development of multicellular organisms. Recently, we analyzed scaling in the context of the early Xenopus embryo, focusing on the determination of the dorsal-ventral axis by a gradient of BMP activation. The ability of this system to withstand extreme perturbation was exemplified in classical experiments performed by Hans Spemann in the early 20th century. Quantitative analysis revealed that patterning is governed by a noncanonical 'shuttling-based' mechanism, and defined the feedback enabling the scaling of pattern with size. Robust scaling is due to molecular implementation of an integral-feedback controller, which adjusts the width of the BMP morphogen gradient with the size of the system. We present an 'expansion-repression' feedback topology which generalizes this concept for a wider range of patterning systems, providing a general, and potentially widely applicable model for the robust scaling of morphogen gradients with size.
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Affiliation(s)
- Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
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Jaeger J, Irons D, Monk N. Regulative feedback in pattern formation: towards a general relativistic theory of positional information. Development 2009; 135:3175-83. [PMID: 18776142 DOI: 10.1242/dev.018697] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Positional specification by morphogen gradients is traditionally viewed as a two-step process. A gradient is formed and then interpreted, providing a spatial metric independent of the target tissue, similar to the concept of space in classical mechanics. However, the formation and interpretation of gradients are coupled, dynamic processes. We introduce a conceptual framework for positional specification in which cellular activity feeds back on positional information encoded by gradients, analogous to the feedback between mass-energy distribution and the geometry of space-time in Einstein's general theory of relativity. We discuss how such general relativistic positional information (GRPI) can guide systems-level approaches to pattern formation.
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Affiliation(s)
- Johannes Jaeger
- Laboratory for Development and Evolution, University Museum of Zoology, Department of Zoology, University of Cambridge, Cambridge, UK.
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