1
|
Mok GF, Turner S, Smith EL, Mincarelli L, Lister A, Lipscombe J, Uzun V, Haerty W, Macaulay IC, Münsterberg AE. Single cell RNA-sequencing and RNA-tomography of the avian embryo extending body axis. Front Cell Dev Biol 2024; 12:1382960. [PMID: 38863942 PMCID: PMC11165230 DOI: 10.3389/fcell.2024.1382960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 04/29/2024] [Indexed: 06/13/2024] Open
Abstract
Introduction: Vertebrate body axis formation initiates during gastrulation and continues within the tail bud at the posterior end of the embryo. Major structures in the trunk are paired somites, which generate the musculoskeletal system, the spinal cord-forming part of the central nervous system, and the notochord, with important patterning functions. The specification of these different cell lineages by key signalling pathways and transcription factors is essential, however, a global map of cell types and expressed genes in the avian trunk is missing. Methods: Here we use high-throughput sequencing approaches to generate a molecular map of the emerging trunk and tailbud in the chick embryo. Results and Discussion: Single cell RNA-sequencing (scRNA-seq) identifies discrete cell lineages including somites, neural tube, neural crest, lateral plate mesoderm, ectoderm, endothelial and blood progenitors. In addition, RNA-seq of sequential tissue sections (RNA-tomography) provides a spatially resolved, genome-wide expression dataset for the avian tailbud and emerging body, comparable to other model systems. Combining the single cell and RNA-tomography datasets, we identify spatially restricted genes, focusing on somites and early myoblasts. Thus, this high-resolution transcriptome map incorporating cell types in the embryonic trunk can expose molecular pathways involved in body axis development.
Collapse
Affiliation(s)
- G. F. Mok
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - S. Turner
- Earlham Institute, Norwich, United Kingdom
| | - E. L. Smith
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | | | - A. Lister
- Earlham Institute, Norwich, United Kingdom
| | | | - V. Uzun
- Earlham Institute, Norwich, United Kingdom
| | - W. Haerty
- Earlham Institute, Norwich, United Kingdom
| | | | - A. E. Münsterberg
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| |
Collapse
|
2
|
Kondoh H, Takemoto T. The Origin and Regulation of Neuromesodermal Progenitors (NMPs) in Embryos. Cells 2024; 13:549. [PMID: 38534393 DOI: 10.3390/cells13060549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/04/2024] [Accepted: 03/18/2024] [Indexed: 03/28/2024] Open
Abstract
Neuromesodermal progenitors (NMPs), serving as the common origin of neural and paraxial mesodermal development in a large part of the trunk, have recently gained significant attention because of their critical importance in the understanding of embryonic organogenesis and the design of in vitro models of organogenesis. However, the nature of NMPs at many essential points remains only vaguely understood or even incorrectly assumed. Here, we discuss the nature of NMPs, focusing on their dynamic migratory behavior during embryogenesis and the mechanisms underlying their neural vs. mesodermal fate choice. The discussion points include the following: (1) How the sinus rhomboidals is organized; the tissue where the neural or mesodermal fate choice of NMPs occurs. (2) NMPs originating from the broad posterior epiblast are associated with Sox2 N1 enhancer activity. (3) Tbx6-dependent Sox2 repression occurs during NMP-derived paraxial mesoderm development. (4) The nephric mesenchyme, a component of the intermediate mesoderm, was newly identified as an NMP derivative. (5) The transition of embryonic tissue development from tissue-specific progenitors in the anterior part to that from NMPs occurs at the forelimb bud axial level. (6) The coexpression of Sox2 and Bra in NMPs is conditional and is not a hallmark of NMPs. (7) The ability of the NMP pool to sustain axial embryo growth depends on Wnt3a signaling in the NMP population. Current in vitro models of NMPs are also critically reviewed.
Collapse
Affiliation(s)
- Hisato Kondoh
- Biohistory Research Hall, Takatsuki 569-1125, Japan
- Osaka University, Suita 565-0871, Japan
| | - Tatsuya Takemoto
- Laboratory for Embryology, Institute for Advanced Medical Sciences, Tokushima University, Tokushima 770-8503, Japan
| |
Collapse
|
3
|
Miao Y, Pourquié O. Cellular and molecular control of vertebrate somitogenesis. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00709-z. [PMID: 38418851 DOI: 10.1038/s41580-024-00709-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 03/02/2024]
Abstract
Segmentation is a fundamental feature of the vertebrate body plan. This metameric organization is first implemented by somitogenesis in the early embryo, when paired epithelial blocks called somites are rhythmically formed to flank the neural tube. Recent advances in in vitro models have offered new opportunities to elucidate the mechanisms that underlie somitogenesis. Notably, models derived from human pluripotent stem cells introduced an efficient proxy for studying this process during human development. In this Review, we summarize the current understanding of somitogenesis gained from both in vivo studies and in vitro studies. We deconstruct the spatiotemporal dynamics of somitogenesis into four distinct modules: dynamic events in the presomitic mesoderm, segmental determination, somite anteroposterior polarity patterning, and epithelial morphogenesis. We first focus on the segmentation clock, as well as signalling and metabolic gradients along the tissue, before discussing the clock and wavefront and other models that account for segmental determination. We then detail the molecular and cellular mechanisms of anteroposterior polarity patterning and somite epithelialization.
Collapse
Affiliation(s)
- Yuchuan Miao
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA, USA.
| |
Collapse
|
4
|
Busby L, Serrano Nájera G, Steventon BJ. Intrinsic and extrinsic cues time somite progenitor contribution to the vertebrate primary body axis. eLife 2024; 13:e90499. [PMID: 38193440 PMCID: PMC10834026 DOI: 10.7554/elife.90499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 01/08/2024] [Indexed: 01/10/2024] Open
Abstract
During embryonic development, the timing of events at the cellular level must be coordinated across multiple length scales to ensure the formation of a well-proportioned body plan. This is clear during somitogenesis, where progenitors must be allocated to the axis over time whilst maintaining a progenitor population for continued elaboration of the body plan. However, the relative importance of intrinsic and extrinsic signals in timing progenitor addition at the single-cell level is not yet understood. Heterochronic grafts from older to younger embryos have suggested a level of intrinsic timing whereby later staged cells contribute to more posterior portions of the axis. To determine the precise step at which cells are delayed, we performed single-cell transcriptomic analysis on heterochronic grafts of somite progenitors in the chicken embryo. This revealed a previously undescribed cell state within which heterochronic grafted cells are stalled. The delayed exit of older cells from this state correlates with expression of posterior Hox genes. Using grafting and explant culture, we find that both Hox gene expression and the migratory capabilities of progenitor populations are intrinsically regulated at the population level. However, by grafting varied sizes of tissue, we find that small heterochronic grafts disperse more readily and contribute to more anterior portions of the body axis while still maintaining Hox gene expression. This enhanced dispersion is not replicated in explant culture, suggesting that it is a consequence of interaction between host and donor tissue and thus extrinsic to the donor tissue. Therefore, we demonstrate that the timing of cell dispersion and resulting axis contribution is impacted by a combination of both intrinsic and extrinsic cues.
Collapse
Affiliation(s)
- Lara Busby
- Department of Genetics, University of CambridgeCambridgeUnited Kingdom
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | | | | |
Collapse
|
5
|
Kondoh H. Gastrulation: Its Principles and Variations. Results Probl Cell Differ 2024; 72:27-60. [PMID: 38509251 DOI: 10.1007/978-3-031-39027-2_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
As epiblast cells initiate development into various somatic cells, they undergo a large-scale reorganization, called gastrulation. The gastrulation of the epiblast cells produces three groups of cells: the endoderm layer, the collection of miscellaneous mesodermal tissues, and the ectodermal layer, which includes the neural, epidermal, and associated tissues. Most studies of gastrulation have focused on the formation of the tissues that provide the primary route for cell reorganization, that is, the primitive streak, in the chicken and mouse. In contrast, how gastrulation alters epiblast-derived cells has remained underinvestigated. This chapter highlights the regulation of cell and tissue fate via the gastrulation process. The roles and regulatory functions of neuromesodermal progenitors (NMPs) in the gastrulation process, elucidated in the last decade, are discussed in depth to resolve points of confusion. Chicken and mouse embryos, which form a primitive streak as the site of mesoderm precursor ingression, have been investigated extensively. However, primitive streak formation is an exception, even among amniotes. The roles of gastrulation processes in generating various somatic tissues will be discussed broadly.
Collapse
Affiliation(s)
- Hisato Kondoh
- Osaka University, Suita, Osaka, Japan
- Biohistory Research Hall, Takatsuki, Osaka, Japan
| |
Collapse
|
6
|
Wang M, Zhang P, Li Z, Yan Y, Cheng X, Wang G, Yang X. Different cellular mechanisms from low- and high-dose zinc oxide nanoparticles-induced heart tube malformation during embryogenesis. Nanotoxicology 2022; 16:580-596. [PMID: 36137004 DOI: 10.1080/17435390.2022.2124130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
With the wide application of nanometer materials in daily life, people pay more attention to the potential toxicity of nanoparticles to human fetal development once the nanoparticles are absorbed into the human body during pregnancy. However, there was no directly solid evidence for ZnO NPs-caused congenital heart defects. Hence, we investigated the effect of ZnO NPs exposure on early cardiogenesis using the chicken/mouse embryo models. First, we showed ZnO NPs reduced H9c2 cell viability in a dose- and time-dependent manner, while cell autophagy was significantly activated too on the same pattern. During early cardiogenesis, ZnO NPs exposure increased the chance of heart tube malformation, while precardiac cell apoptosis rises in the phenotype of closure defect and Bifida. The hypertrophy was also observed in late-stage chicken/mouse survival embryos exposed to ZnO NPs. Apart from cell apoptosis, high-dose ZnO NPs exposure led to massive programmed necrosis, and further experiments verified that ferroptosis remained primarily in ZnO NPs-induced programmed necrosis. We also revealed that the toxicology of low-dose ZnO NPs was mainly featured in the changes of expressions of key genes instead of causing precardiac cell death. MYL2 and CSRP3 could work as the downstream molecules of the above key genes in the context of ZnO NPs exposure to early cardiogenesis based on RNA sequencing. Taken together, this study for the first time revealed the potential risk of heart tube malformation induced by ZnO NPs exposure through different cellular mechanisms, which depended on low- or high-dose ZnO NPs.
Collapse
Affiliation(s)
- Mengwei Wang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou, China.,International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China
| | - Ping Zhang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou, China.,International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China.,Department of Gynaecology and Obstetrics, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Zeyu Li
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou, China.,International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China
| | - Yu Yan
- School of Nursing, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xin Cheng
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou, China.,International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China
| | - Guang Wang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou, China.,International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China
| | - Xuesong Yang
- Division of Histology & Embryology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Medical College, Jinan University, Guangzhou, China.,International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Piatkowska AM, Evans SE, Stern CD. Cellular aspects of somite formation in vertebrates. Cells Dev 2021; 168:203732. [PMID: 34391979 DOI: 10.1016/j.cdev.2021.203732] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/04/2021] [Accepted: 08/04/2021] [Indexed: 10/20/2022]
Abstract
Vertebrate segmentation, the process that generates a regular arrangement of somites and thereby establishes the pattern of the adult body and of the musculoskeletal and peripheral nervous systems, was noticed many centuries ago. In the last few decades, there has been renewed interest in the process and especially in the molecular mechanisms that might account for its regularity and other spatial-temporal properties. Several models have been proposed but surprisingly, most of these do not provide clear links between the molecular mechanisms and the cell behaviours that generate the segmental pattern. Here we present a short survey of our current knowledge about the cellular aspects of vertebrate segmentation and the similarities and differences between different vertebrate groups in how they achieve their metameric pattern. Taking these variations into account should help to assess each of the models more appropriately.
Collapse
Affiliation(s)
- Agnieszka M Piatkowska
- Department of Cell and Developmental Biology, University College London, Gower Street (Anatomy Building), London WC1E 6BT, UK
| | - Susan E Evans
- Department of Cell and Developmental Biology, University College London, Gower Street (Anatomy Building), London WC1E 6BT, UK
| | - Claudio D Stern
- Department of Cell and Developmental Biology, University College London, Gower Street (Anatomy Building), London WC1E 6BT, UK.
| |
Collapse
|
9
|
Guillot C, Djeffal Y, Michaut A, Rabe B, Pourquié O. Dynamics of primitive streak regression controls the fate of neuromesodermal progenitors in the chicken embryo. eLife 2021; 10:64819. [PMID: 34227938 PMCID: PMC8260230 DOI: 10.7554/elife.64819] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 06/23/2021] [Indexed: 12/20/2022] Open
Abstract
In classical descriptions of vertebrate development, the segregation of the three embryonic germ layers completes by the end of gastrulation. Body formation then proceeds in a head to tail fashion by progressive deposition of lineage-committed progenitors during regression of the primitive streak (PS) and tail bud (TB). The identification by retrospective clonal analysis of a population of neuromesodermal progenitors (NMPs) contributing to both musculoskeletal precursors (paraxial mesoderm) and spinal cord during axis formation challenged these notions. However, classical fate mapping studies of the PS region in amniotes have so far failed to provide direct evidence for such bipotential cells at the single-cell level. Here, using lineage tracing and single-cell RNA sequencing in the chicken embryo, we identify a resident cell population of the anterior PS epiblast, which contributes to neural and mesodermal lineages in trunk and tail. These cells initially behave as monopotent progenitors as classically described and only acquire a bipotential fate later, in more posterior regions. We show that NMPs exhibit a conserved transcriptomic signature during axis elongation but lose their epithelial characteristicsin the TB. Posterior to anterior gradients of convergence speed and ingression along the PS lead to asymmetric exhaustion of PS mesodermal precursor territories. Through limited ingression and increased proliferation, NMPs are maintained and amplified as a cell population which constitute the main progenitors in the TB. Together, our studies provide a novel understanding of the PS and TB contribution through the NMPs to the formation of the body of amniote embryos.
Collapse
Affiliation(s)
- Charlene Guillot
- Department of Pathology, Brigham and Women's Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States.,Harvard Stem Cell Institute, Boston, United States
| | - Yannis Djeffal
- Department of Pathology, Brigham and Women's Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States.,Harvard Stem Cell Institute, Boston, United States
| | - Arthur Michaut
- Department of Pathology, Brigham and Women's Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States.,Harvard Stem Cell Institute, Boston, United States
| | - Brian Rabe
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Boston, United States
| | - Olivier Pourquié
- Department of Pathology, Brigham and Women's Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States.,Harvard Stem Cell Institute, Boston, United States
| |
Collapse
|
10
|
Characterising open chromatin in chick embryos identifies cis-regulatory elements important for paraxial mesoderm formation and axis extension. Nat Commun 2021; 12:1157. [PMID: 33608545 PMCID: PMC7895974 DOI: 10.1038/s41467-021-21426-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 01/25/2021] [Indexed: 01/31/2023] Open
Abstract
Somites arising from paraxial mesoderm are a hallmark of the segmented vertebrate body plan. They form sequentially during axis extension and generate musculoskeletal cell lineages. How paraxial mesoderm becomes regionalised along the axis and how this correlates with dynamic changes of chromatin accessibility and the transcriptome remains unknown. Here, we report a spatiotemporal series of ATAC-seq and RNA-seq along the chick embryonic axis. Footprint analysis shows differential coverage of binding sites for several key transcription factors, including CDX2, LEF1 and members of HOX clusters. Associating accessible chromatin with nearby expressed genes identifies cis-regulatory elements (CRE) for TCF15 and MEOX1. We determine their spatiotemporal activity and evolutionary conservation in Xenopus and human. Epigenome silencing of endogenous CREs disrupts TCF15 and MEOX1 gene expression and recapitulates phenotypic abnormalities of anterior-posterior axis extension. Our integrated approach allows dissection of paraxial mesoderm regulatory circuits in vivo and has implications for investigating gene regulatory networks.
Collapse
|
11
|
Wymeersch FJ, Wilson V, Tsakiridis A. Understanding axial progenitor biology in vivo and in vitro. Development 2021; 148:148/4/dev180612. [PMID: 33593754 DOI: 10.1242/dev.180612] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The generation of the components that make up the embryonic body axis, such as the spinal cord and vertebral column, takes place in an anterior-to-posterior (head-to-tail) direction. This process is driven by the coordinated production of various cell types from a pool of posteriorly-located axial progenitors. Here, we review the key features of this process and the biology of axial progenitors, including neuromesodermal progenitors, the common precursors of the spinal cord and trunk musculature. We discuss recent developments in the in vitro production of axial progenitors and their potential implications in disease modelling and regenerative medicine.
Collapse
Affiliation(s)
- Filip J Wymeersch
- Laboratory for Human Organogenesis, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, 650-0047, Japan
| | - Valerie Wilson
- Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Anestis Tsakiridis
- Centre for Stem Cell Biology, Department of Biomedical Science, The University of Sheffield, Western Bank, Sheffield S10 2TN UK .,Neuroscience Institute, The University of Sheffield, Western Bank, Sheffield, S10 2TN UK
| |
Collapse
|
12
|
Diaz‐Cuadros M, Pourquie O. In vitro systems: A new window to the segmentation clock. Dev Growth Differ 2021; 63:140-153. [PMID: 33460448 PMCID: PMC8048467 DOI: 10.1111/dgd.12710] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 01/12/2023]
Abstract
Segmental organization of the vertebrate body plan is established by the segmentation clock, a molecular oscillator that controls the periodicity of somite formation. Given the dynamic nature of the segmentation clock, in vivo studies in vertebrate embryos pose technical challenges. As an alternative, simpler models of the segmentation clock based on primary explants and pluripotent stem cells have recently been developed. These ex vivo and in vitro systems enable more quantitative analysis of oscillatory properties and expand the experimental repertoire applicable to the segmentation clock. Crucially, by eliminating the need for model organisms, in vitro models allow us to study the segmentation clock in new species, including our own. The human oscillator was recently recapitulated using induced pluripotent stem cells, providing a window into human development. Certainly, a combination of in vivo and in vitro work holds the most promising potential to unravel the mechanisms behind vertebrate segmentation.
Collapse
Affiliation(s)
- Margarete Diaz‐Cuadros
- Department of GeneticsHarvard Medical SchoolBostonMassachusettsUSA
- Department of PathologyBrigham and Women’s HospitalBostonMassachusettsUSA
| | - Olivier Pourquie
- Department of GeneticsHarvard Medical SchoolBostonMassachusettsUSA
- Department of PathologyBrigham and Women’s HospitalBostonMassachusettsUSA
- Harvard Stem Cell InstituteBostonMassachusettsUSA
| |
Collapse
|
13
|
Nakajima T, Ikeya M. Development of pluripotent stem cell-based human tenocytes. Dev Growth Differ 2020; 63:38-46. [PMID: 33270251 DOI: 10.1111/dgd.12702] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/17/2020] [Accepted: 11/18/2020] [Indexed: 12/12/2022]
Abstract
Human pluripotent stem cells (PSCs) are used as a platform for therapeutic purposes such as cell transplantation therapy and drug discovery. Another motivation for studying PSCs is to understand human embryogenesis and development. All cell types that make up the body tissues develop through defined trajectories during embryogenesis. For example, paraxial mesoderm is considered to differentiate into several cell types including skeletal muscle cells, chondrocytes, osteocytes, dermal fibroblasts, and tenocytes. Tenocytes are fibroblast cells that constitute the tendon. The step-wise narrowing fate decisions of paraxial mesoderm in the embryo have been modeled in vitro using PSCs; however, deriving tenocytes from human-induced PSCs and their application in cell therapy have long been challenging. PSC-derived tenocytes can be used for a source of cell transplantation to treat a damaged or ruptured tendon due to injury, disorder, or aging. In this review, we discuss the latest research findings on the use of PSCs for studying the biology of tenocyte development and their application in therapeutic settings.
Collapse
Affiliation(s)
- Taiki Nakajima
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.,Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Makoto Ikeya
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| |
Collapse
|
14
|
Abstract
In birds as in all amniotes, the site of gastrulation is a midline structure, the primitive streak. This appears as cells in the one cell-thick epiblast undergo epithelial-to-mesenchymal transition to ingress and form definitive mesoderm and endoderm. Global movements involving tens of thousands of cells in the embryonic epiblast precede gastrulation. They position the primitive streak precursors from a marginal position (equivalent to the situation in anamniotes) along the future antero-posterior axis (typical for amniotes). These epithelial movements continue in modified form during gastrulation, when they are accompanied by collective movements of different class in the forming mesoderm and endoderm. Here I discuss the nature of these collective cell movements shaping the embryo, their interplay with signaling events controlling fate specification and significance in an evolutionary perspective.
Collapse
|
15
|
Bénazéraf B. Dynamics and mechanisms of posterior axis elongation in the vertebrate embryo. Cell Mol Life Sci 2019; 76:89-98. [PMID: 30283977 PMCID: PMC11105343 DOI: 10.1007/s00018-018-2927-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 12/27/2022]
Abstract
During development, the vertebrate embryo undergoes significant morphological changes which lead to its future body form and functioning organs. One of these noticeable changes is the extension of the body shape along the antero-posterior (A-P) axis. This A-P extension, while taking place in multiple embryonic tissues of the vertebrate body, involves the same basic cellular behaviors: cell proliferation, cell migration (of new progenitors from a posterior stem zone), and cell rearrangements. However, the nature and the relative contribution of these different cellular behaviors to A-P extension appear to vary depending upon the tissue in which they take place and on the stage of embryonic development. By focusing on what is known in the neural and mesodermal tissues of the bird embryo, I review the influences of cellular behaviors in posterior tissue extension. In this context, I discuss how changes in distinct cell behaviors can be coordinated at the tissue level (and between tissues) to synergize, build, and elongate the posterior part of the embryonic body. This multi-tissue framework does not only concern axis elongation, as it could also be generalized to morphogenesis of any developing organs.
Collapse
Affiliation(s)
- Bertrand Bénazéraf
- Centre de Biologie du Développement (CBD), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France.
| |
Collapse
|
16
|
Nakajima T, Shibata M, Nishio M, Nagata S, Alev C, Sakurai H, Toguchida J, Ikeya M. Modeling human somite development and fibrodysplasia ossificans progressiva with induced pluripotent stem cells. Development 2018; 145:145/16/dev165431. [PMID: 30139810 PMCID: PMC6124548 DOI: 10.1242/dev.165431] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 07/24/2018] [Indexed: 12/27/2022]
Abstract
Somites (SMs) comprise a transient stem cell population that gives rise to multiple cell types, including dermatome (D), myotome (MYO), sclerotome (SCL) and syndetome (SYN) cells. Although several groups have reported induction protocols for MYO and SCL from pluripotent stem cells, no studies have demonstrated the induction of SYN and D from SMs. Here, we report systematic induction of these cells from human induced pluripotent stem cells (iPSCs) under chemically defined conditions. We also successfully induced cells with differentiation capacities similar to those of multipotent mesenchymal stromal cells (MSC-like cells) from SMs. To evaluate the usefulness of these protocols, we conducted disease modeling of fibrodysplasia ossificans progressiva (FOP), an inherited disease that is characterized by heterotopic endochondral ossification in soft tissues after birth. Importantly, FOP-iPSC-derived MSC-like cells showed enhanced chondrogenesis, whereas FOP-iPSC-derived SCL did not, possibly recapitulating normal embryonic skeletogenesis in FOP and cell-type specificity of FOP phenotypes. These results demonstrate the usefulness of multipotent SMs for disease modeling and future cell-based therapies. Summary: Protocols for the differentiation of human iPSCs to somite derivatives (myotome, sclerotome, syndetome and dermatome) are developed and applied to the modeling of the bone disease fibrodysplasia ossificans progressiva.
Collapse
Affiliation(s)
- Taiki Nakajima
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Mitsuaki Shibata
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Megumi Nishio
- Department of Tissue Regeneration, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Sanae Nagata
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Cantas Alev
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Hidetoshi Sakurai
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Junya Toguchida
- Department of Tissue Regeneration, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.,Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan.,Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | - Makoto Ikeya
- Department of Clinical Application, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| |
Collapse
|
17
|
Abstract
The skeletal muscle lineage derives from the embryonic paraxial mesoderm (PM) which also gives rise to the axial skeleton, the dermis of the back, brown fat, meninges, and endothelial cells. Direct conversion was pioneered in skeletal muscle with overexpression of the transcription factor MyoD which can convert fibroblasts to a muscle fate. In contrast, directed differentiation of skeletal muscle from pluripotent cells (PC) in vitro has proven to be very difficult compared to other lineages and has only been achieved recently. Experimental strategies recapitulating myogenesis in vitro from mouse and human PC (ES/iPS) have now been reported and all rely on early activation of Wnt signaling at the epiblast stage. This leads to induction of neuromesodermal progenitors that can subsequently be induced to a PM fate and to skeletal muscle. These protocols can efficiently produce fetal muscle fibers and immature satellite cells. These new in vitro systems now open the possibility to better understand human myogenesis and to develop in vitro disease models as well as cell therapy approaches.
Collapse
Affiliation(s)
- Olivier Pourquié
- Brigham and Women's Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States; Harvard Stem Cell Institute, Boston, MA, United States.
| | - Ziad Al Tanoury
- Brigham and Women's Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States; Harvard Stem Cell Institute, Boston, MA, United States
| | - Jérome Chal
- Brigham and Women's Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States; Harvard Stem Cell Institute, Boston, MA, United States
| |
Collapse
|
18
|
Abstract
Organizers, which comprise groups of cells with the ability to instruct adjacent cells into specific states, represent a key principle in developmental biology. The concept was first introduced by Spemann and Mangold, who showed that there is a cellular population in the newt embryo that elicits the development of a secondary axis from adjacent cells. Similar experiments in chicken and rabbit embryos subsequently revealed groups of cells with similar instructive potential. In birds and mammals, organizer activity is often associated with a structure known as the node, which has thus been considered a functional homologue of Spemann's organizer. Here, we take an in-depth look at the structure and function of organizers across species and note that, whereas the amphibian organizer is a contingent collection of elements, each performing a specific function, the elements of organizers in other species are dispersed in time and space. This observation urges us to reconsider the universality and meaning of the organizer concept. Summary: This Review re-evaluates the notion of Spemann's organizer as identified in amphibians, highlighting the spatiotemporal dispersion of equivalent elements in mouse and the key influence of responsiveness to organizer signals.
Collapse
Affiliation(s)
| | - Ben Steventon
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| |
Collapse
|
19
|
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]
|
20
|
Abstract
Collinear regulation of Hox genes in space and time has been an outstanding question ever since the initial work of Ed Lewis in 1978. Here we discuss recent advances in our understanding of this phenomenon in relation to novel concepts associated with large-scale regulation and chromatin structure during the development of both axial and limb patterns. We further discuss how this sequential transcriptional activation marks embryonic stem cell-like axial progenitors in mammals and, consequently, how a temporal genetic system is further translated into spatial coordinates via the fate of these progenitors. In this context, we argue the benefit and necessity of implementing this unique mechanism as well as the difficulty in evolving an alternative strategy to deliver this critical positional information.
Collapse
Affiliation(s)
- Jacqueline Deschamps
- Hubrecht Institute, University Medical Center Utrecht, 3584 CT Utrecht, the Netherlands
| | - Denis Duboule
- School of Life Sciences, Ecole Polytechnique Fédérale, Lausanne, 1015 Lausanne, Switzerland.,Department of Genetics and Evolution, University of Geneva, 1211 Geneva 4, Switzerland
| |
Collapse
|
21
|
Abstract
Skeletal muscle is the largest tissue in the body and loss of its function or its regenerative properties results in debilitating musculoskeletal disorders. Understanding the mechanisms that drive skeletal muscle formation will not only help to unravel the molecular basis of skeletal muscle diseases, but also provide a roadmap for recapitulating skeletal myogenesis in vitro from pluripotent stem cells (PSCs). PSCs have become an important tool for probing developmental questions, while differentiated cell types allow the development of novel therapeutic strategies. In this Review, we provide a comprehensive overview of skeletal myogenesis from the earliest premyogenic progenitor stage to terminally differentiated myofibers, and discuss how this knowledge has been applied to differentiate PSCs into muscle fibers and their progenitors in vitro.
Collapse
Affiliation(s)
- Jérome Chal
- Department of Pathology, Brigham and Women's Hospital, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.,Harvard Stem Cell Institute, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Olivier Pourquié
- Department of Pathology, Brigham and Women's Hospital, 77 Avenue Louis Pasteur, Boston, MA 02115, USA .,Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.,Harvard Stem Cell Institute, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.,Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS (UMR 7104), Inserm U964, Université de Strasbourg, 67400 Illkirch-Graffenstaden, France
| |
Collapse
|
22
|
Abstract
In the developing vertebrate embryo, segmentation initiates through the formation of repeated segments, or somites, on either side of the posterior neural tube along the anterior to posterior axis. The periodicity of somitogenesis is regulated by a molecular oscillator, the segmentation clock, driving cyclic gene expression in the unsegmented paraxial mesoderm, from which somites derive. Three signaling pathways underlie the molecular mechanism of the oscillator: Wnt, FGF, and Notch. In particular, Notch has been demonstrated to be an essential piece in the intricate somitogenesis regulation puzzle. Notch is required to synchronize oscillations between neighboring cells, and is moreover necessary for somite formation and clock gene oscillations. Following ligand activation, the Notch receptor is cleaved to liberate the active intracellular domain (NICD) and during somitogenesis NICD itself is produced and degraded in a cyclical manner, requiring tightly regulated, and coordinated turnover. It was recently shown that the pace of the segmentation clock is exquisitely sensitive to levels/stability of NICD. In this review, we focus on what is known about the mechanisms regulating NICD turnover, crucial to the activity of the pathway in all developmental contexts. To date, the regulation of NICD stability has been attributed to phosphorylation of the PEST domain which serves to recruit the SCF/Sel10/FBXW7 E3 ubiquitin ligase complex involved in NICD turnover. We will describe the pathophysiological relevance of NICD-FBXW7 interaction, whose defects have been linked to leukemia and a variety of solid cancers.
Collapse
Affiliation(s)
- Francesca A Carrieri
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee Dundee, UK
| | - Jacqueline Kim Dale
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee Dundee, UK
| |
Collapse
|
23
|
Kimelman D. Tales of Tails (and Trunks): Forming the Posterior Body in Vertebrate Embryos. Curr Top Dev Biol 2016; 116:517-36. [PMID: 26970638 DOI: 10.1016/bs.ctdb.2015.12.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A major question in developmental biology is how the early embryonic axes are established. Recent studies using different model organisms and mammalian in vitro systems have revealed the surprising result that most of the early posterior embryonic body forms from a Wnt-regulated bipotential neuromesodermal progenitor population that escapes early germ layer patterning. Part of the regulatory network that drives the maintenance and differentiation of these progenitors has recently been determined, but much remains to be discovered. This review discusses some of the common features present in all vertebrates, as well as unique aspects that different species utilize to establish their anterior-posterior (A-P) axis.
Collapse
Affiliation(s)
- David Kimelman
- Department of Biochemistry, University of Washington, Seattle, Washington, USA.
| |
Collapse
|
24
|
Wymeersch FJ, Huang Y, Blin G, Cambray N, Wilkie R, Wong FCK, Wilson V. Position-dependent plasticity of distinct progenitor types in the primitive streak. eLife 2016; 5:e10042. [PMID: 26780186 PMCID: PMC4798969 DOI: 10.7554/elife.10042] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 01/14/2016] [Indexed: 12/22/2022] Open
Abstract
The rostrocaudal (head-to-tail) axis is supplied by populations of progenitors at the caudal end of the embryo. Despite recent advances characterising one of these populations, the neuromesodermal progenitors, their nature and relationship to other populations remains unclear. Here we show that neuromesodermal progenitors are a single Sox2lowTlow entity whose choice of neural or mesodermal fate is dictated by their position in the progenitor region. The choice of mesoderm fate is Wnt/β-catenin dependent. Wnt/β-catenin signalling is also required for a previously unrecognised phase of progenitor expansion during mid-trunk formation. Lateral/ventral mesoderm progenitors represent a distinct committed state that is unable to differentiate to neural fates, even upon overexpression of the neural transcription factor Sox2. They do not require Wnt/β-catenin signalling for mesoderm differentiation. This information aids the correct interpretation of in vivo genetic studies and the development of in vitro protocols for generating physiologically-relevant cell populations of clinical interest. DOI:http://dx.doi.org/10.7554/eLife.10042.001 Our bodies, like those of all animals with a backbone, form during embryo development in a head-to-tail sequence. This process is fuelled by populations of proliferating cells called progenitor cells, which are found in an early embryonic structure called the primitive streak, and later at the tail-end of the embryo. One of these populations – known as the neuromesodermal progenitors (or NMPs) – produces the animal’s spinal cord, muscle and bone tissue. However, it is not clear how this cell population is maintained or what triggers these cells to specialise into the correct cell type. It is even unclear whether NMPs are a single cell type or a collection of several types of progenitor, each with a slightly different propensity to make spinal cord or muscle and bone. Answering these questions could inform the future development of cell-replacement therapies for conditions such as spinal injuries. Wymeersch et al. used a range of techniques to identify, map the fate, and assess the developmental potential of progenitors in the primitive streak. This revealed fine-grained differences in the fates adopted by cells in the progenitor region. However, these regional differences were found to result from the progenitor cells’ extensive ability to respond to signals they receive from their environment, rather than being hard-wired into the progenitor cells. In fact, Wymeersch et al. detected only two distinct cell types: the NMPs and a new cell population termed lateral/paraxial mesoderm progenitors (or LPMPs), which, unlike NMPs, do not form nerve cells. Further experiments investigated the molecular signals present in the environment of these progenitors that help to decide their fate. NMPs respond to an important developmental signal, called Wnt, by adopting a so-called mesoderm fate. This signal also induces NMPs to undergo a previously unknown phase of proliferation during the formation of the animal’s body. LPMPs, on the other hand, do not require Wnt to form mesoderm. These findings show that studies with embryos can identify new progenitor populations that might be clinically relevant, and reveal new ways in which a cell’s environment inside an embryo can determine its fate. DOI:http://dx.doi.org/10.7554/eLife.10042.002
Collapse
Affiliation(s)
- Filip J Wymeersch
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Yali Huang
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Guillaume Blin
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Noemí Cambray
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ron Wilkie
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Frederick C K Wong
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Valerie Wilson
- MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
25
|
Sheeba CJ, Andrade RP, Palmeirim I. Mechanisms of vertebrate embryo segmentation: Common themes in trunk and limb development. Semin Cell Dev Biol 2016; 49:125-34. [DOI: 10.1016/j.semcdb.2016.01.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/07/2016] [Indexed: 01/02/2023]
|
26
|
Independent regulation of vertebral number and vertebral identity by microRNA-196 paralogs. Proc Natl Acad Sci U S A 2015; 112:E4884-93. [PMID: 26283362 DOI: 10.1073/pnas.1512655112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The Hox genes play a central role in patterning the embryonic anterior-to-posterior axis. An important function of Hox activity in vertebrates is the specification of different vertebral morphologies, with an additional role in axis elongation emerging. The miR-196 family of microRNAs (miRNAs) are predicted to extensively target Hox 3' UTRs, although the full extent to which miR-196 regulates Hox expression dynamics and influences mammalian development remains to be elucidated. Here we used an extensive allelic series of mouse knockouts to show that the miR-196 family of miRNAs is essential both for properly patterning vertebral identity at different axial levels and for modulating the total number of vertebrae. All three miR-196 paralogs, 196a1, 196a2, and 196b, act redundantly to pattern the midthoracic region, whereas 196a2 and 196b have an additive role in controlling the number of rib-bearing vertebra and positioning of the sacrum. Independent of this, 196a1, 196a2, and 196b act redundantly to constrain total vertebral number. Loss of miR-196 leads to a collective up-regulation of numerous trunk Hox target genes with a concomitant delay in activation of caudal Hox genes, which are proposed to signal the end of axis extension. Additionally, we identified altered molecular signatures associated with the Wnt, Fgf, and Notch/segmentation pathways and demonstrate that miR-196 has the potential to regulate Wnt activity by multiple mechanisms. By feeding into, and thereby integrating, multiple genetic networks controlling vertebral number and identity, miR-196 is a critical player defining axial formulae.
Collapse
|
27
|
Denans N, Iimura T, Pourquié O. Hox genes control vertebrate body elongation by collinear Wnt repression. eLife 2015; 4. [PMID: 25719209 PMCID: PMC4384752 DOI: 10.7554/elife.04379] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 02/20/2015] [Indexed: 12/23/2022] Open
Abstract
In vertebrates, the total number of vertebrae is precisely defined. Vertebrae derive
from embryonic somites that are continuously produced posteriorly from the presomitic
mesoderm (PSM) during body formation. We show that in the chicken embryo, activation
of posterior Hox genes (paralogs 9–13) in the tail-bud
correlates with the slowing down of axis elongation. Our data indicate that a subset
of progressively more posterior Hox genes, which are collinearly
activated in vertebral precursors, repress Wnt activity with increasing strength.
This leads to a graded repression of the Brachyury/T transcription
factor, reducing mesoderm ingression and slowing down the elongation process. Due to
the continuation of somite formation, this mechanism leads to the progressive
reduction of PSM size. This ultimately brings the retinoic acid (RA)-producing
segmented region in close vicinity to the tail bud, potentially accounting for the
termination of segmentation and axis elongation. DOI:http://dx.doi.org/10.7554/eLife.04379.001 In humans and other vertebrates, the number of bones (vertebrae) in the spine is
determined early in development. The vertebrae form from blocks of tissue called
somites that make segments along the body axis—a virtual line running from the
head to the tail-end—of the embryo. The somites form as the embryo increases
in length, with new somites forming periodically at the back near the embryo's
tail-end. A family of genes called the Hox genes are involved in controlling
the formation of the somites. However, it is not known whether they directly control
the number of somites that form, or whether they control the length of the body of
the embryo. Denans et al. studied the Hox genes in chicken embryos. The
experiments suggest that the activation of some of the Hox genes in
a structure called the tail-bud, which is found at the tail-end of the embryo, slow
down the elongation of the body. The Hox genes achieve this by
repressing the activity of a signaling pathway called Wnt so that Wnt activity in the
tail-bud progressively decreases as the embryo develops. The elongation of the body stops when the levels of a molecule called retinoic acid
increase in the tail-bud, which causes the loss of the stem cells that are needed to
make the somites. Denans et al.'s findings suggest that Hox
genes influence the timing of the halt in elongation, which in turn is important for
determining the total number of somites that form. Understanding how
Hox genes control the formation of the cells that will make up
the somites and influence Wnt signaling is a major challenge for the future. DOI:http://dx.doi.org/10.7554/eLife.04379.002
Collapse
Affiliation(s)
- Nicolas Denans
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, University of Strasbourg, Illkirch, France
| | - Tadahiro Iimura
- Stowers Institute for Medical Research, Kansas City, United States
| | - Olivier Pourquié
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, University of Strasbourg, Illkirch, France
| |
Collapse
|
28
|
Timing embryo segmentation: dynamics and regulatory mechanisms of the vertebrate segmentation clock. BIOMED RESEARCH INTERNATIONAL 2014; 2014:718683. [PMID: 24895605 PMCID: PMC4033425 DOI: 10.1155/2014/718683] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/09/2014] [Indexed: 11/18/2022]
Abstract
All vertebrate species present a segmented body, easily observed in the vertebrate column and its associated components, which provides a high degree of motility to the adult body and efficient protection of the internal organs. The sequential formation of the segmented precursors of the vertebral column during embryonic development, the somites, is governed by an oscillating genetic network, the somitogenesis molecular clock. Herein, we provide an overview of the molecular clock operating during somite formation and its underlying molecular regulatory mechanisms. Human congenital vertebral malformations have been associated with perturbations in these oscillatory mechanisms. Thus, a better comprehension of the molecular mechanisms regulating somite formation is required in order to fully understand the origin of human skeletal malformations.
Collapse
|
29
|
Wang X, Li Y, Wang G, Münsterberg A, Chuai M, Lee KK, Wang L, Yang X. Combinational electroporation and transplantation approach to studying gene functions in avian embryos. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-013-0090-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
30
|
Neijts R, Simmini S, Giuliani F, van Rooijen C, Deschamps J. Region-specific regulation of posterior axial elongation during vertebrate embryogenesis. Dev Dyn 2013; 243:88-98. [PMID: 23913366 DOI: 10.1002/dvdy.24027] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/18/2013] [Accepted: 07/21/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The vertebrate body axis extends sequentially from the posterior tip of the embryo, fueled by the gastrulation process at the primitive streak and its continuation within the tailbud. Anterior structures are generated early, and subsequent nascent tissues emerge from the posterior growth zone and continue to elongate the axis until its completion. The underlying processes have been shown to be disrupted in mouse mutants, some of which were described more than half a century ago. RESULTS Important progress in elucidating the cellular and genetic events involved in body axis elongation has recently been made on several fronts. Evidence for the residence of self-renewing progenitors, some of which are bipotential for neurectoderm and mesoderm, has been obtained by embryo-grafting techniques and by clonal analyses in the mouse embryo. Transcription factors of several families including homeodomain proteins have proven instrumental for regulating the axial progenitor niche in the growth zone. A complex genetic network linking these transcription factors and signaling molecules is being unraveled that underlies the phenomenon of tissue lengthening from the axial stem cells. The concomitant events of cell fate decision among descendants of these progenitors begin to be better understood at the levels of molecular genetics and cell behavior. CONCLUSIONS The emerging picture indicates that the ontogenesis of the successive body regions is regulated according to different rules. In addition, parameters controlling vertebrate axial length during evolution have emerged from comparative experimental studies. It is on these issues that this review will focus, mainly addressing the study of axial extension in the mouse embryo with some comparison with studies in chick and zebrafish, aiming at unveiling the recent progress, and pointing at still unanswered questions for a thorough understanding of the process of embryonic axis elongation.
Collapse
Affiliation(s)
- Roel Neijts
- Hubrecht Institute and University Medical Center, Utrecht, The Netherlands
| | | | | | | | | |
Collapse
|
31
|
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.
Collapse
Affiliation(s)
- Bertrand Bénazéraf
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS (UMR 7104), Université de Strasbourg, Illkirch F-67400, France;
| | | |
Collapse
|
32
|
Abstract
Gastrulation, the process that puts the three major germlayers, the ectoderm, mesoderm and endoderm in their correct topological position in the developing embryo, is characterised by extensive highly organised collective cell migration of epithelial and mesenchymal cells. We discuss current knowledge and insights in the mechanisms controlling these cell behaviours during gastrulation in the chick embryo. We discuss several ideas that have been proposed to explain the observed large scale vortex movements of epithelial cells in the epiblast during formation of the primitive streak. We review current insights in the control and execution of the epithelial to mesenchymal transition (EMT) underlying the formation of the hypoblast and the ingression of the mesendoderm cells through the streak. We discuss the mechanisms by which the mesendoderm cells move, the nature and dynamics of the signals that guide these movements, as well as the interplay between signalling and movement that result in tissue patterning and morphogenesis. We argue that instructive cell-cell signaling and directed chemotactic movement responses to these signals are instrumental in the execution of all phases of gastrulation.
Collapse
Affiliation(s)
- Manli Chuai
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | | | | |
Collapse
|
33
|
Iimura T, Nakane A, Sugiyama M, Sato H, Makino Y, Watanabe T, Takagi Y, Numano R, Yamaguchi A. A fluorescence spotlight on the clockwork development and metabolism of bone. J Bone Miner Metab 2012; 30:254-69. [PMID: 21766187 DOI: 10.1007/s00774-011-0295-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 06/10/2011] [Indexed: 01/26/2023]
Abstract
Biological phenomena that exhibit periodic activity are often referred as biorhythms or biological clocks. Among these, circadian rhythms, cyclic patterns reflecting a 24-h cycle, are the most obvious in many physiological activities including bone growth and metabolism. In the late 1990s, several clock genes were isolated and their primary structures and functions were identified. The feedback loop model of transcriptional factors was proposed to work as a circadian core oscillator not only in the suprachiasmatic nuclei of the anterior hypothalamus, which is recognized as the mammalian central clock, but also in various peripheral tissues including cartilage and bone. Looking back to embryonic development, the fundamental architecture of skeletal patterning is regulated by ultradian clocks that are defined as biorhythms that cycle more than once every 24 h. As post-genomic approaches, transcriptome analysis by micro-array and bioimaging assays to detect luminescent and fluorescent signals have been exploited to uncover a more comprehensive set of genes and spatio-temporal regulation of the clockwork machinery in animal models. In this review paper, we provide an overview of topics related to these molecular clocks in skeletal biology and medicine, and discuss how fluorescence imaging approaches can contribute to widening our views of this realm of biomedical science.
Collapse
Affiliation(s)
- Tadahiro Iimura
- Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Abstract
Many of the morphogenetic processes that occur during development in the mouse are based on cyclic events with defined time intervals, as exemplified by somitogenesis (every 2 h), hair cycles (every 25 d), and spermatogenesis (every 35 d). Among these events, somitogenesis is the most dynamic morphogenetic mechanism showing clear cyclicity during embryogenesis and is therefore a good system with which to review the synchronous and cyclic characteristics of developmental pathways. The metameric properties of the somites underpin the segmental properties along the anterior-posterior (AP) axis of the body. The periodicity of somites is controlled by the so-called segmentation clock operating in the presomitic mesoderm (PSM). This tissue contains the somite precursor cells that exist only during embryonic development. Both theoretical and experimental approaches have contributed to the understanding of the mechanism of somite segmentation. This article focuses on how the segmentation clock functions to organize the collective behavior of cells and how this information is translated into the spatial patterning of segmental somites. The interplay between signaling molecules that provides positional information and the transcription factors that respond to such positional cues are critical to the role of the segmentation clock and are discussed.
Collapse
|
35
|
Venters SJ, Ordahl CP. Somite unit chronometry to analyze teratogen phase specificity in the paraxial mesoderm. Methods Mol Biol 2012; 798:103-123. [PMID: 22130834 DOI: 10.1007/978-1-61779-343-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Phase specificity, the temporal and tissue restriction of teratogen-induced defects during embryonic -development, is a poorly understood but common property of teratogens, an important source of human birth defects. Somite counting and somite units are novel chronometric tools used here to identify stages of paraxial mesoderm development that are sensitive to pulse-chase exposure (2 to >16 h) to 5-bromodeoxyuridine (BrdU). In all cases, it was the presomitic mesoderm (PSM) that was sensitive to BrdU induced segmentation anomalies. At high concentration (1.0 × 10(-2) M BrdU), PSM presegment stages ss-IV and earlier were irreversibly inhibited from completing segmentation. At low concentration (2.6 × 10(-6) M), BrdU induced periodic focal defects that predominantly trace back to PSM presegments between ss-V and ss-IX. Phase specificity is characteristic of both types of segmentation anomalies. Focal segmentation defects are phase-specific because they result from disruption of 2-3 presegments in the PSM while adjacent -rostral and caudal presegments are (apparently) unaffected. Irreversible inhibition of segmentation is also phase-specific because only PSM presegments ss-IV or earlier were affected while older segments (ss-III to ss-I) were able to complete segmentation. The presegments predominantly affected have not yet passed the determination front, the point at which the segmentation clock establishes somite rostro-caudal -polarity. Somite unit chronometry provides a means to identify specific PSM presegment stages that are susceptible to induced segmentation defects and the biological processes that underlie that vulnerability.
Collapse
Affiliation(s)
- Sara J Venters
- Department of Neurosurgery, School of Medicine, University of California, San Francisco, CA, USA
| | | |
Collapse
|
36
|
Iimura T, Sugiyama M, Watanabe T, Nakane A, Makino Y, Yamaguchi A. Lighting up Skeletal Biology by Fluorescent Imaging. J Oral Biosci 2011. [DOI: 10.1016/s1349-0079(11)80012-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
37
|
Protogenin mediates cell adhesion for ingression and re-epithelialization of paraxial mesodermal cells. Dev Biol 2010; 351:13-24. [PMID: 21129372 DOI: 10.1016/j.ydbio.2010.11.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 11/10/2010] [Accepted: 11/19/2010] [Indexed: 11/22/2022]
Abstract
In the avian embryo, precursor cells of the paraxial mesoderm that reside in the epiblast ingress through the primitive streak and migrate bilaterally in an anterolateral direction. Herein, we report on the roles of Protogenin (PRTG), an immunoglobulin superfamily protein expressed on the surface of the ingressing and migrating cells that give rise to the paraxial mesoderm, in paraxial mesoderm development. An aggregation assay using L-cells showed that PRTG mediates homophilic cell adhesion. Overexpression of PRTG in the presumptive paraxial mesoderm delayed mesodermal cell migration due to augmented adhesiveness. In contrast, siRNA knockdown of PRTG impaired successive ingression of epiblast cells and disorganized the epithelial structure of the somites. These results suggest that PRTG mediates cell adhesion to regulate continuous ingression of cells giving rise to the paraxial mesodermal lineage, as well as tissue integrity.
Collapse
|
38
|
Krneta-Stankic V, Sabillo A, Domingo CR. Temporal and spatial patterning of axial myotome fibers in Xenopus laevis. Dev Dyn 2010; 239:1162-77. [PMID: 20235228 DOI: 10.1002/dvdy.22275] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Somites give rise to the vertebral column and segmented musculature of adult vertebrates. The cell movements that position cells within somites along the anteroposterior and dorsoventral axes are not well understood. Using a fate mapping approach, we show that at the onset of Xenopus laevis gastrulation, mesoderm cells undergo distinct cell movements to form myotome fibers positioned in discrete locations within somites and along the anteroposterior axis. We show that the distribution of presomitic cells along the anteroposterior axis is influenced by convergent and extension movements of the notochord. Heterochronic and heterotopic transplantations between presomitic gastrula and early tail bud stages show that these cells are interchangeable and can form myotome fibers in locations determined by the host embryo. However, additional transplantation experiments revealed differences in the competency of presomitic cells to form myotome fibers, suggesting that maturation within the tail bud presomitic mesoderm is required for myotome fiber differentiation.
Collapse
Affiliation(s)
- Vanja Krneta-Stankic
- Department of Biology, San Francisco State University, San Francisco, California 94132, USA
| | | | | |
Collapse
|
39
|
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.
Collapse
Affiliation(s)
- Cantas Alev
- Laboratory for Early Embryogenesis, RIKEN Center for Developmental Biology, Kobe, Hyogo, Japan
| | | | | | | | | | | |
Collapse
|
40
|
Tenin G, Wright D, Ferjentsik Z, Bone R, McGrew MJ, Maroto M. The chick somitogenesis oscillator is arrested before all paraxial mesoderm is segmented into somites. BMC DEVELOPMENTAL BIOLOGY 2010; 10:24. [PMID: 20184730 PMCID: PMC2836991 DOI: 10.1186/1471-213x-10-24] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Accepted: 02/25/2010] [Indexed: 11/10/2022]
Abstract
BACKGROUND Somitogenesis is the earliest sign of segmentation in the developing vertebrate embryo. This process starts very early, soon after gastrulation has initiated and proceeds in an anterior-to-posterior direction during body axis elongation. It is widely accepted that somitogenesis is controlled by a molecular oscillator with the same periodicity as somite formation. This periodic mechanism is repeated a specific number of times until the embryo acquires a defined specie-specific final number of somites at the end of the process of axis elongation. This final number of somites varies widely between vertebrate species. How termination of the process of somitogenesis is determined is still unknown. RESULTS Here we show that during development there is an imbalance between the speed of somite formation and growth of the presomitic mesoderm (PSM)/tail bud. This decrease in the PSM size of the chick embryo is not due to an acceleration of the speed of somite formation because it remains constant until the last stages of somitogenesis, when it slows down. When the chick embryo reaches its final number of somites at stage HH 24-25 there is still some remaining unsegmented PSM in which expression of components of the somitogenesis oscillator is no longer dynamic. Finally, we identify a change in expression of retinoic acid regulating factors in the tail bud at late stages of somitogenesis, such that in the chick embryo there is a pronounced onset of Raldh2 expression while in the mouse embryo the expression of the RA inhibitor Cyp26A1 is downregulated. CONCLUSIONS Our results show that the chick somitogenesis oscillator is arrested before all paraxial mesoderm is segmented into somites. In addition, endogenous retinoic acid is probably also involved in the termination of the process of segmentation, and in tail growth in general.
Collapse
Affiliation(s)
- Gennady Tenin
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dow Street, Dundee, UK
| | | | | | | | | | | |
Collapse
|
41
|
Alexander T, Nolte C, Krumlauf R. Hox genes and segmentation of the hindbrain and axial skeleton. Annu Rev Cell Dev Biol 2010; 25:431-56. [PMID: 19575673 DOI: 10.1146/annurev.cellbio.042308.113423] [Citation(s) in RCA: 240] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Segmentation is an important process that is frequently used during development to segregate groups of cells with distinct features. Segmental compartments provide a mechanism for generating and organizing regional properties along an embryonic axis and within tissues. In vertebrates the development of two major systems, the hindbrain and the paraxial mesoderm, displays overt signs of compartmentalization and depends on the process of segmentation for their functional organization. The hindbrain plays a key role in regulating head development, and it is a complex coordination center for motor activity, breathing rhythms, and many unconscious functions. The paraxial mesoderm generates somites, which give rise to the axial skeleton. The cellular processes of segmentation in these two systems depend on ordered patterns of Hox gene expression as a mechanism for generating a combinatorial code that specifies unique identities of the segments and their derivatives. In this review, we compare and contrast the signaling inputs and transcriptional mechanisms by which Hox gene regulatory networks are established during segmentation in these two different systems.
Collapse
Affiliation(s)
- Tara Alexander
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
| | | | | |
Collapse
|
42
|
Iimura T, Himeno A, Nakane A, Yamaguchi A. Hox Genes, a Molecular Constraint for the Development and Evolution of the Vertebrate Body Plan. J Oral Biosci 2010. [DOI: 10.1016/s1349-0079(10)80045-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
43
|
Gomez C, Pourquié O. Developmental control of segment numbers in vertebrates. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2009; 312:533-44. [PMID: 19621429 DOI: 10.1002/jez.b.21305] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Segmentation or metamery in vertebrates is best illustrated by the repetition of the vertebrae and ribs, their associated skeletal muscles and blood vessels, and the spinal nerves and ganglia. The segment number varies tremendously among the different vertebrate species, ranging from as few as six vertebrae in some frogs to as many as several hundred in some snakes and fish. In vertebrates, metameric segments or somites form sequentially during body axis formation. This results in the embryonic axis becoming entirely segmented into metameric units from the level of the otic vesicle almost to the very tip of the tail. The total segment number mostly depends on two parameters: (1) the control of the posterior growth of the body axis during somitogenesis-more same-size segments can be formed in a longer axis and (2) segment size--more smaller--size segments can be formed in a same-size body axis. During evolution, independent variations of these parameters could explain the huge diversity in segment numbers observed among vertebrate species. These variations in segment numbers are accompanied by diversity in the regionalization of the vertebral column. For example, amniotes can exhibit up to five different types of vertebrae: cervical, thoracic, lumbar, sacral and caudal, the number of which varies according to the species. This regionalization of the vertebral column is controlled by the Hox family of transcription factors. We propose that during development, dissociation of the Hox- and segmentation-clock-dependent vertebral patterning systems explains the enormous diversity of vertebral formulae observed in vertebrates.
Collapse
Affiliation(s)
- Céline Gomez
- University of Cambridge, Cambridge, United Kingdom
| | | |
Collapse
|
44
|
Tzouanacou E, Wegener A, Wymeersch FJ, Wilson V, Nicolas JF. Redefining the progression of lineage segregations during mammalian embryogenesis by clonal analysis. Dev Cell 2009; 17:365-76. [PMID: 19758561 DOI: 10.1016/j.devcel.2009.08.002] [Citation(s) in RCA: 269] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 06/24/2009] [Accepted: 08/11/2009] [Indexed: 10/20/2022]
Abstract
Clonal lineage information is fundamental in revealing cell fate choices. Using genetic single-cell labeling in utero, we investigated lineage segregations during anteroposterior axis formation in mouse. We show that while endoderm and surface ectoderm segregate during gastrulation, neural ectoderm and mesoderm share a common progenitor persisting through all stages of axis elongation. These data challenge the paradigm that the three germ layers, formed by gastrulation, constitute the primary branchpoints in differentiation of the pluripotent epiblast toward tissue-specific precursors. Bipotent neuromesodermal progenitors show self-renewing characteristics and may represent the cellular substrate coupling sustained axial elongation and coordinated differentiation of these tissues. These findings have important implications for the interpretation of the phenotypic defects of several mouse mutants and the directed differentiation of embryonic stem (ES) cells in vitro.
Collapse
Affiliation(s)
- Elena Tzouanacou
- Institut Pasteur, Département de Biologie du Développement, CNRS URA 2578, 25 rue du Dr. Roux, 75724 Paris cedex 15, France.
| | | | | | | | | |
Collapse
|
45
|
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.
Collapse
|
46
|
Regulation of cell migration during chick gastrulation. Curr Opin Genet Dev 2009; 19:343-9. [PMID: 19647425 DOI: 10.1016/j.gde.2009.06.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/30/2009] [Accepted: 06/30/2009] [Indexed: 01/10/2023]
Abstract
Gastrulation in chick starts with large-scale cell flows in the epiblast and hypoblast, which transport the mesendoderm into the midline of the embryo to form the primitive streak. Several mechanisms such as cell-cell intercalation, deformations of the extracellular matrix and directed cell movements in response to chemical gradients have been proposed to play a role in streak formation. In the streak the epiblast cells undergo an epithelial to mesenchymal transition (EMT), which involves the breakdown of apical junctions and changes in RhoA-dependent signalling to integrins that mediated contact with the basal lamina. The collective migration of the mesendoderm away from the streak appears to be controlled by gradients of growth factors of the FGF and VEGF and Wnt families and requires N-cadherin expression. The timing and order of ingression of epiblast cells appears to be controlled by temporal and spatial colinearity of Hox gene expression in the epiblast. The mechanisms by which Hox genes control these properties remain to be resolved.
Collapse
|
47
|
Iimura T, Denans N, Pourquié O. Establishment of Hox vertebral identities in the embryonic spine precursors. Curr Top Dev Biol 2009; 88:201-34. [PMID: 19651306 DOI: 10.1016/s0070-2153(09)88007-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The vertebrate spine exhibits two striking characteristics. The first one is the periodic arrangement of its elements-the vertebrae-along the anteroposterior axis. This segmented organization is the result of somitogenesis, which takes place during organogenesis. The segmentation machinery involves a molecular oscillator-the segmentation clock-which delivers a periodic signal controlling somite production. During embryonic axis elongation, this signal is displaced posteriorly by a system of traveling signaling gradients-the wavefront-which depends on the Wnt, FGF, and retinoic acid pathways. The other characteristic feature of the spine is the subdivision of groups of vertebrae into anatomical domains, such as the cervical, thoracic, lumbar, sacral, and caudal regions. This axial regionalization is controlled by a set of transcription factors called Hox genes. Hox genes exhibit nested expression domains in the somites which reflect their linear arrangement along the chromosomes-a property termed colinearity. The colinear disposition of Hox genes expression domains provides a blueprint for the regionalization of the future vertebral territories of the spine. In amniotes, Hox genes are activated in the somite precursors of the epiblast in a temporal colinear sequence and they were proposed to control their progressive ingression into the nascent paraxial mesoderm. Consequently, the positioning of the expression domains of Hox genes along the anteroposterior axis is largely controlled by the timing of Hox activation during gastrulation. Positioning of the somitic Hox domains is subsequently refined through a crosstalk with the segmentation machinery in the presomitic mesoderm. In this review, we focus on our current understanding of the embryonic mechanisms that establish vertebral identities during vertebrate development.
Collapse
|
48
|
Abstract
The introduction of in ovo electroporation a decade ago has helped the chick embryo to become a powerful system to study gene regulation and function during development. Although this is a simple procedure for embryos of 2-d incubation, earlier stages (from laying to early neurulation, 0-1 d) present special challenges. Here we describe a robust and reproducible protocol for electroporation of expression vectors and morpholino oligonucleotides into the epiblast of embryos from soon after laying (stage XI) to stages 6-7 (early neurulation), with precise spatial and temporal control. Within 3 h, about 12 embryos can be electroporated and set up for culture by the New technique; the effects of morpholinos can be assessed immediately after electroporation, and robust overexpression from plasmid DNA is seen 2-3 h after electroporation. These techniques can be used for time-lapse imaging, gain- and loss-of-function experiments and studying gene regulatory elements in living embryos.
Collapse
|
49
|
Yang X, Chrisman H, Weijer CJ. PDGF signalling controls the migration of mesoderm cells during chick gastrulation by regulating N-cadherin expression. Development 2008; 135:3521-30. [DOI: 10.1242/dev.023416] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In the early chick embryo, Pdgfa is expressed in the epiblast,outlining the migration route that mesoderm cells expressing the receptor, Pdgfrα, follow to form somites. Both expression of a dominant-negative PDGFRα and depletion of endogenous PDGFRαligands through injection of PDGFRα-Fc fragments, inhibit the migration of mesoderm cells after their ingression through the primitive streak. siRNA-mediated downregulation of Pdgfa expression in the epiblast on one side of the streak strongly blocks the migration of mesoderm cells into that side. Beads soaked in PDGFA elicit a directional attractive movement response in mesoderm cells, showing that PDGFA can provide directional information. Surprisingly, however, PDGF signalling is also required for directional movement towards other attractants, such as FGF4. PDGF signalling controls N-cadherin expression on mesoderm cells, which is required for efficient migration. PDGF signalling activates the PI3 kinase signalling pathway in vivo and activation of this pathway is required for proper N-cadherin expression.
Collapse
Affiliation(s)
- Xuesong Yang
- Division of Cell and Developmental Biology, Wellcome Trust Biocentre,College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Holly Chrisman
- Division of Cell and Developmental Biology, Wellcome Trust Biocentre,College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Cornelis J. Weijer
- Division of Cell and Developmental Biology, Wellcome Trust Biocentre,College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| |
Collapse
|
50
|
Freter S, Muta Y, Mak SS, Rinkwitz S, Ladher RK. Progressive restriction of otic fate: the role of FGF and Wnt in resolving inner ear potential. Development 2008; 135:3415-24. [PMID: 18799542 DOI: 10.1242/dev.026674] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The development of the vertebrate inner ear is an emergent process. Its progression from a relatively simple disk of thickened epithelium within head ectoderm into a complex organ capable of sensing sound and balance is controlled by sequential molecular and cellular interactions. Fibroblast growth factor (FGF) and Wnt signals emanating from mesoderm and neural ectoderm have been shown to direct inner ear fate. However, the role of these multiple signals during inner ear induction is unclear. We demonstrate that the action of the FGFs and Wnts is sequential, and that their roles support a model of hierarchical fate decisions that progressively restrict the developmental potential of the ectoderm until otic commitment. We show that signalling by Fgf3 and Fgf19 is required to initiate a proliferative progenitor region that is a precursor to both the inner ear and the neurogenic epibranchial placodes. Significantly, we find that only after FGF action is attenuated can the subsequent action of Wnt signalling allow otic differentiation to proceed. In addition, gain and loss of function of Wnt-signalling components show a role for this signalling in repressing epibranchial fate. This interplay of signalling factors ensures the correct and ordered differentiation of both inner ear and epibranchial systems.
Collapse
Affiliation(s)
- Sabine Freter
- Laboratory for Sensory Development, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | | | | | | | | |
Collapse
|