1
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Keum BR, Yeo I, Koo Y, Han W, Choi SC, Kim GH, Han JK. Transmembrane protein 150b attenuates BMP signaling in the Xenopus organizer. J Cell Physiol 2023; 238:1850-1866. [PMID: 37435758 DOI: 10.1002/jcp.31059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 05/03/2023] [Accepted: 05/06/2023] [Indexed: 07/13/2023]
Abstract
The vertebrate organizer is a specified embryonic tissue that regulates dorsoventral patterning and axis formation. Although numerous cellular signaling pathways have been identified as regulators of the organizer's dynamic functions, the process remains incompletely understood, and as-yet unknown pathways remain to be explored for sophisticated mechanistic understanding of the vertebrate organizer. To identify new potential key factors of the organizer, we performed complementary DNA (cDNA) microarray screening using organizer-mimicking Xenopus laevis tissue. This analysis yielded a list of prospective organizer genes, and we determined the role of six-transmembrane domain containing transmembrane protein 150b (Tmem150b) in organizer function. Tmem150b was expressed in the organizer region and induced by Activin/Nodal signaling. In X. laevis, Tmem150b knockdown resulted in head defects and a shortened body axis. Moreover, Tmem150b negatively regulated bone morphogenetic protein (BMP) signaling, likely via physical interaction with activin receptor-like kinase 2 (ALK2). These findings demonstrated that Tmem150b functions as a novel membrane regulatory factor of BMP signaling with antagonistic effects, contributing to the understanding of regulatory molecular mechanisms of organizer axis function. Investigation of additional candidate genes identified in the cDNA microarray analysis could further delineate the genetic networks of the organizer during vertebrate embryogenesis.
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Affiliation(s)
- Byeong-Rak Keum
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
- Research Center for drug development, CYPHARMA, Daejeon, Korea
| | - Inchul Yeo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| | - Youngmu Koo
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
| | - Wonhee Han
- Department of Neurology, F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Sun-Cheol Choi
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Gun-Hwa Kim
- Research Center for drug development, CYPHARMA, Daejeon, Korea
- Research Center for Bioconvergence Analysis, Korea Basic Science Institute, Cheongju, Korea
| | - Jin-Kwan Han
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea
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2
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Piacentino ML, Bronner ME. Intracellular attenuation of BMP signaling via CKIP-1/Smurf1 is essential during neural crest induction. PLoS Biol 2018; 16:e2004425. [PMID: 29949573 PMCID: PMC6039030 DOI: 10.1371/journal.pbio.2004425] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 07/10/2018] [Accepted: 06/13/2018] [Indexed: 01/22/2023] Open
Abstract
The neural crest is induced at the neural plate border during gastrulation by combined bone morphogenetic protein (BMP), fibroblast growth factor (FGF), and Wnt signaling. While intermediate BMP levels are critical for this induction, secreted BMP inhibitors are largely absent from the neural plate border. Here, we propose a morphogen model in which intracellular attenuation of BMP signaling sets the required intermediate levels to maintain neural crest induction. We show that the scaffold protein casein kinase interacting protein 1 (CKIP-1) and ubiquitin ligase Smad ubiquitin regulatory factor 1 (Smurf1) are coexpressed with BMP4 at the chick neural plate border. Knockdown of CKIP-1 during a critical period between gastrulation and neurulation causes neural crest loss. Consistent with specific BMP modulation, CKIP-1 loss suppresses phospho-Smads 1/5/8 (pSmad1/5/8) and BMP reporter output but has no effect on Wnt signaling; Smurf1 overexpression (OE) acts similarly. Epistasis experiments further show that CKIP-1 rescues Smurf1-mediated neural crest loss. The results support a model in which CKIP-1 suppresses Smurf1-mediated degradation of Smads, uncovering an intracellular mechanism for attenuation of BMP signaling to the intermediate levels required for maintenance of neural crest induction.
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Affiliation(s)
- Michael L. Piacentino
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Marianne E. Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
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3
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Ravindran E, Hu H, Yuzwa SA, Hernandez-Miranda LR, Kraemer N, Ninnemann O, Musante L, Boltshauser E, Schindler D, Hübner A, Reinecker HC, Ropers HH, Birchmeier C, Miller FD, Wienker TF, Hübner C, Kaindl AM. Homozygous ARHGEF2 mutation causes intellectual disability and midbrain-hindbrain malformation. PLoS Genet 2017; 13:e1006746. [PMID: 28453519 PMCID: PMC5428974 DOI: 10.1371/journal.pgen.1006746] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 05/12/2017] [Accepted: 04/05/2017] [Indexed: 11/18/2022] Open
Abstract
Mid-hindbrain malformations can occur during embryogenesis through a disturbance of transient and localized gene expression patterns within these distinct brain structures. Rho guanine nucleotide exchange factor (ARHGEF) family members are key for controlling the spatiotemporal activation of Rho GTPase, to modulate cytoskeleton dynamics, cell division, and cell migration. We identified, by means of whole exome sequencing, a homozygous frameshift mutation in the ARHGEF2 as a cause of intellectual disability, a midbrain-hindbrain malformation, and mild microcephaly in a consanguineous pedigree of Kurdish-Turkish descent. We show that loss of ARHGEF2 perturbs progenitor cell differentiation and that this is associated with a shift of mitotic spindle plane orientation, putatively favoring more symmetric divisions. The ARHGEF2 mutation leads to reduction in the activation of the RhoA/ROCK/MLC pathway crucial for cell migration. We demonstrate that the human brain malformation is recapitulated in Arhgef2 mutant mice and identify an aberrant migration of distinct components of the precerebellar system as a pathomechanism underlying the midbrain-hindbrain phenotype. Our results highlight the crucial function of ARHGEF2 in human brain development and identify a mutation in ARHGEF2 as novel cause of a neurodevelopmental disorder.
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Affiliation(s)
- Ethiraj Ravindran
- Institute of Cell Biology and Neurobiology, Charité University Medicine Berlin, Berlin, Germany
- Department of Pediatric Neurology, Charité University Medicine Berlin, Berlin, Germany
- Sozialpädiatrisches Zentrum (SPZ), Center for Chronic Sick Children, Charité University, Berlin, Germany
| | - Hao Hu
- Max Planck Institute for Molecular Genetics, Berlin, Germany
- Guangzhou Women and Children's Medical Center, Guangzhou, China
| | - Scott A. Yuzwa
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
| | | | - Nadine Kraemer
- Institute of Cell Biology and Neurobiology, Charité University Medicine Berlin, Berlin, Germany
- Department of Pediatric Neurology, Charité University Medicine Berlin, Berlin, Germany
- Sozialpädiatrisches Zentrum (SPZ), Center for Chronic Sick Children, Charité University, Berlin, Germany
| | - Olaf Ninnemann
- Institute of Cell Biology and Neurobiology, Charité University Medicine Berlin, Berlin, Germany
| | - Luciana Musante
- Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Eugen Boltshauser
- Department of Pediatric Neurology, University Children's Hospital of Zurich, Zurich, Switzerland
| | - Detlev Schindler
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Angela Hübner
- Pediatrics, University Hospital, Technical University Dresden, Dresden, Germany
| | - Hans-Christian Reinecker
- Gastrointestinal Unit and Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | | | | | - Freda D. Miller
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
- Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Canada
| | | | - Christoph Hübner
- Department of Pediatric Neurology, Charité University Medicine Berlin, Berlin, Germany
| | - Angela M. Kaindl
- Institute of Cell Biology and Neurobiology, Charité University Medicine Berlin, Berlin, Germany
- Department of Pediatric Neurology, Charité University Medicine Berlin, Berlin, Germany
- Sozialpädiatrisches Zentrum (SPZ), Center for Chronic Sick Children, Charité University, Berlin, Germany
- * E-mail:
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4
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Jang S, Choubey S, Furchtgott L, Zou LN, Doyle A, Menon V, Loew EB, Krostag AR, Martinez RA, Madisen L, Levi BP, Ramanathan S. Dynamics of embryonic stem cell differentiation inferred from single-cell transcriptomics show a series of transitions through discrete cell states. eLife 2017; 6:20487. [PMID: 28296635 PMCID: PMC5352225 DOI: 10.7554/elife.20487] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 01/31/2017] [Indexed: 02/06/2023] Open
Abstract
The complexity of gene regulatory networks that lead multipotent cells to acquire different cell fates makes a quantitative understanding of differentiation challenging. Using a statistical framework to analyze single-cell transcriptomics data, we infer the gene expression dynamics of early mouse embryonic stem (mES) cell differentiation, uncovering discrete transitions across nine cell states. We validate the predicted transitions across discrete states using flow cytometry. Moreover, using live-cell microscopy, we show that individual cells undergo abrupt transitions from a naïve to primed pluripotent state. Using the inferred discrete cell states to build a probabilistic model for the underlying gene regulatory network, we further predict and experimentally verify that these states have unique response to perturbations, thus defining them functionally. Our study provides a framework to infer the dynamics of differentiation from single cell transcriptomics data and to build predictive models of the gene regulatory networks that drive the sequence of cell fate decisions during development. DOI:http://dx.doi.org/10.7554/eLife.20487.001
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Affiliation(s)
- Sumin Jang
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Sandeep Choubey
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Leon Furchtgott
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Biophysics Program, Harvard University, Cambridge, United States
| | - Ling-Nan Zou
- FAS Center for Systems Biology, Harvard University, Cambridge, United States
| | - Adele Doyle
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | - Vilas Menon
- Allen Institute for Brain Science, Seattle, United States
| | - Ethan B Loew
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States
| | | | | | - Linda Madisen
- Allen Institute for Brain Science, Seattle, United States
| | - Boaz P Levi
- Allen Institute for Brain Science, Seattle, United States
| | - Sharad Ramanathan
- FAS Center for Systems Biology, Harvard University, Cambridge, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Allen Institute for Brain Science, Seattle, United States.,School of Engineering and Applied Sciences, Harvard University, Cambridge, United States.,Harvard Stem Cell Institute, Harvard University, Cambridge, United States
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5
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Bhinge A, Poschmann J, Namboori SC, Tian X, Jia Hui Loh S, Traczyk A, Prabhakar S, Stanton LW. MiR-135b is a direct PAX6 target and specifies human neuroectoderm by inhibiting TGF-β/BMP signaling. EMBO J 2014; 33:1271-83. [PMID: 24802670 DOI: 10.1002/embj.201387215] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Several transcription factors (TFs) have been implicated in neuroectoderm (NE) development, and recently, the TF PAX6 was shown to be critical for human NE specification. However, microRNA networks regulating human NE development have been poorly documented. We hypothesized that microRNAs activated by PAX6 should promote NE development. Using a genomics approach, we identified PAX6 binding sites and active enhancers genome-wide in an in vitro model of human NE development that was based on neural differentiation of human embryonic stem cells (hESC). PAX6 binding to active enhancers was found in the proximity of several microRNAs, including hsa-miR-135b. MiR-135b was activated during NE development, and ectopic expression of miR-135b in hESC promoted differentiation toward NE. MiR-135b promotes neural conversion by targeting components of the TGF-β and BMP signaling pathways, thereby inhibiting differentiation into alternate developmental lineages. Our results demonstrate a novel TF-miRNA module that is activated during human neuroectoderm development and promotes the irreversible fate specification of human pluripotent cells toward the neural lineage.
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Affiliation(s)
- Akshay Bhinge
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Jeremie Poschmann
- Computational and Systems Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Seema C Namboori
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Xianfeng Tian
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Sharon Jia Hui Loh
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Anna Traczyk
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Shyam Prabhakar
- Computational and Systems Biology, Genome Institute of Singapore, Singapore City, Singapore
| | - Lawrence W Stanton
- Stem Cell and Developmental Biology, Genome Institute of Singapore, Singapore City, Singapore Department of Biological Sciences, National University of Singapore, Singapore City, Singapore School of Biological Sciences Nanyang Technological University, Singapore City, Singapore
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6
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Engberg N, Kahn M, Petersen DR, Hansson M, Serup P. Retinoic acid synthesis promotes development of neural progenitors from mouse embryonic stem cells by suppressing endogenous, Wnt-dependent nodal signaling. Stem Cells 2010; 28:1498-509. [PMID: 20665854 DOI: 10.1002/stem.479] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Embryonic stem (ES) cells differentiate spontaneously toward a neuroectodermal fate in serum-free, adherent monocultures. Here, we show that this spontaneous neural fate requires retinoic acid (RA) synthesis. We monitor ES cells containing reporter genes for markers of the early neural plate as well as the primitive streak and its progeny to determine the cell fates induced when RA signaling is perturbed. We demonstrate that the spontaneous neural commitment of mouse ES cells requires endogenous RA production from vitamin A (vitA) in the medium. Formation of neural progenitors is inhibited by removing vitA from the medium, by inhibiting the enzymes that catalyze the synthesis of RA, or by inhibiting RA receptors. We show that subnanomolar concentrations of RA restore neuroectodermal differentiation when RA synthesis is blocked. We demonstrate that a neural to mesodermal fate change occurring when RA signaling is inhibited is dependent on Nodal-, Wnt-, and fibroblast growth factor-signaling. We show that Nodal suppresses neural development in a Wnt-dependent manner and that Wnt-mediated inhibition of neural development is reversed by inhibition of Nodal signaling. Together, our results show that neural induction in ES cells requires RA at subnanomolar levels to suppress Nodal signaling and suggest that the mechanism by which Wnt signaling suppresses neural development is through facilitation of Nodal signaling.
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Affiliation(s)
- Nina Engberg
- Department of Stem Cell Biology, Hagedorn Research Institute, Gentofte, Denmark
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7
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Ishii Y, Garriock RJ, Navetta AM, Coughlin LE, Mikawa T. BMP signals promote proepicardial protrusion necessary for recruitment of coronary vessel and epicardial progenitors to the heart. Dev Cell 2010; 19:307-16. [PMID: 20708592 DOI: 10.1016/j.devcel.2010.07.017] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 04/21/2010] [Accepted: 07/26/2010] [Indexed: 11/25/2022]
Abstract
The coronary vessels and epicardium arise from an extracardiac rudiment called the proepicardium. Failed fusion of the proepicardium to the heart results in severe coronary and heart defects. However, it is unknown how the proepicardium protrudes toward and attaches to the looping heart tube. Here, we show that ectopic expression of BMP ligands in the embryonic myocardium can cause proepicardial cells to target aberrant regions of the heart. Additionally, misexpression of a BMP antagonist, Noggin, suppresses proepicardium protrusion and contact with the heart. Finally, proepicardium explant preferentially expands toward a cocultured heart segment. This preference can be mimicked by BMP2/4 and suppressed by Noggin. These results support a model in which myocardium-derived BMP signals regulate the entry of coronary progenitors to the specific site of the heart by directing their morphogenetic movement.
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Affiliation(s)
- Yasuo Ishii
- Cardiovascular Research Institute, University of California, San Francisco, 94158, USA
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8
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Villegas SN, Canham M, Brickman JM. FGF signalling as a mediator of lineage transitions--evidence from embryonic stem cell differentiation. J Cell Biochem 2010; 110:10-20. [PMID: 20336694 DOI: 10.1002/jcb.22536] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The fibroblast growth factor (FGF) signalling pathway is one of the most ubiquitous in biology. It has diverse roles in development, differentiation and cancer. Embryonic stem (ES) cells are in vitro cell lines capable of differentiating into all the lineages of the conceptus. As such they have the capacity to differentiate into derivatives of all three germ layers and to some extent the extra-embryonic lineages as well. Given the prominent role of FGF signalling in early embryonic development, we explore the role of this pathway in early ES cell differentiation towards the major lineages of the embryo. As early embryonic differentiation is intricately choreographed at the level of morphogenetic movement, adherent ES cell culture affords a unique opportunity to study the basic steps in early lineage specification in the absence of ever shifting complex in vivo microenvironments. Thus recent experiments in ES cell differentiation are able to pinpoint specific FGF dependent lineage transitions that are difficult to resolve in vivo. Here we review the role of FGF signalling in early development alongside the ES cell data and suggest that FGF dependent signalling via phospho-Erk activation maybe a major mediator of transitions in lineage specification.
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Affiliation(s)
- Santiago Nahuel Villegas
- Institute for Stem Cell Research, MRC Centre for Regenerative Medicine, King's Buildings, West Mains Rd., Edinburgh EH9 3JQ, UK
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9
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Sagha M, Karbalaie K, Tanhaee S, Esfandiari E, Salehi H, Sadeghi-Aliabadi H, Razavi S, Nasr-Esfahani MH, Baharvand H. Neural Induction in Mouse Embryonic Stem Cells by Co-Culturing With Chicken Somites. Stem Cells Dev 2009; 18:1351-60. [DOI: 10.1089/scd.2008.0341] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Mohsen Sagha
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
- Department of Anatomical Sciences, School of Medicine, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Khadijeh Karbalaie
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Somaieh Tanhaee
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Ebrahim Esfandiari
- Department of Anatomical Sciences, School of Medicine, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Hossein Salehi
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Hojjat Sadeghi-Aliabadi
- Department of Pharmaceutical Chemistry, School of Pharmacy and Esfahan Pharmaceutical Research Center, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Shahnaz Razavi
- Department of Anatomical Sciences, School of Medicine, Esfahan University of Medical Sciences, Esfahan, Iran
| | - Mohammad Hossein Nasr-Esfahani
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
| | - Hossein Baharvand
- Department of Stem Cells, Cell Science Research Center, Royan Institute, Esfahan Campus, Iranian Academic Center for Education, Culture, and Research (ACECR), Esfahan, Iran
- Department of Developmental Biology, University of Science and Culture, Iranian Academic Center for Education, Culture, and Research (ACECR), Tehran, Iran
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10
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Watanabe H, Fujisawa T, Holstein TW. Cnidarians and the evolutionary origin of the nervous system. Dev Growth Differ 2009; 51:167-83. [PMID: 19379274 DOI: 10.1111/j.1440-169x.2009.01103.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cnidarians are widely regarded as one of the first organisms in animal evolution possessing a nervous system. Conventional histological and electrophysiological studies have revealed a considerable degree of complexity of the cnidarian nervous system. Thanks to expressed sequence tags and genome projects and the availability of functional assay systems in cnidarians, this simple nervous system is now genetically accessible and becomes particularly valuable for understanding the origin and evolution of the genetic control mechanisms underlying its development. In the present review, the anatomical and physiological features of the cnidarian nervous system and the interesting parallels in neurodevelopmental mechanisms between Cnidaria and Bilateria are discussed.
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Affiliation(s)
- Hiroshi Watanabe
- University of Heidelberg, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany.
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11
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Lee KW, Moreau M, Néant I, Bibonne A, Leclerc C. FGF-activated calcium channels control neural gene expression in Xenopus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1033-40. [DOI: 10.1016/j.bbamcr.2008.12.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 12/03/2008] [Accepted: 12/04/2008] [Indexed: 01/29/2023]
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12
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Cell communication with the neural plate is required for induction of neural markers by BMP inhibition: evidence for homeogenetic induction and implications for Xenopus animal cap and chick explant assays. Dev Biol 2009; 327:478-86. [PMID: 19162002 DOI: 10.1016/j.ydbio.2008.12.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 12/09/2008] [Accepted: 12/22/2008] [Indexed: 11/20/2022]
Abstract
In Xenopus, the animal cap is very sensitive to BMP antagonists, which result in neuralization. In chick, however, only cells at the border of the neural plate can be neuralized by BMP inhibition. Here we compare the two systems. BMP antagonists can induce neural plate border markers in both ventral Xenopus epidermis and non-neural chick epiblast. However, BMP antagonism can only neuralize ectodermal cells when the BMP-inhibited cells form a continuous trail connecting them to the neural plate or its border, suggesting that homeogenetic neuralizing factors can only travel between BMP-inhibited cells. Xenopus animal cap explants contain cells fated to contribute to the neural plate border and even to the anterior neural plate, explaining why they are so easily neuralized by BMP-inhibition. Furthermore, chick explants isolated from embryonic epiblast behave like Xenopus animal caps and express border markers. We propose that the animal cap assay in Xenopus and explant assays in the chick are unsuitable for studying instructive signals in neural induction.
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13
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Lenka N, Ramasamy SK. Neural induction from ES cells portrays default commitment but instructive maturation. PLoS One 2007; 2:e1349. [PMID: 18092007 PMCID: PMC2121127 DOI: 10.1371/journal.pone.0001349] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Accepted: 12/04/2007] [Indexed: 11/18/2022] Open
Abstract
The neural induction has remained a debatable issue pertaining to whether it is a mere default process or it involves precise instructive cues. We have chosen the embryonic stem (ES) cell model to address this issue. In a devised monoculture strategy, the cell-cell interaction availed through optimum cell plating density could define the niche for the attainment of efficient in vitro neurogenesis from the ES cells. The medium plating density was found ideal in generating optimum number of progenitors and also yielded about 80% mature neurons in a serum free culture set up barring any exogenous inducers. We could also demarcate and quantify the neural stem cells/progenitors among the heterogeneous cell population of differentiating ES cells using nestin intron II driven EGFP expression as a tool. The one week post-plating was determined to be the critical time window for optimum neural progenitor generation from ES cells that helped us further in purifying these cells and in demonstrating their proliferation and multipotent differentiation potential. Seeding cells at varying densities, we could decipher an interesting paradoxical scenario that interlinked both commitment and maturation with the initial plating density having a vital influence on neuronal maturation but not specification and the secretory factors were apparently playing a key role during this process. Thus it was comprehended that, the neural specification was a default process independent of exogenous factors and cellular interaction. Conversely, a defined number of cells at the specification stage itself seemed critical to provide an auto-/paracrine means of signaling threshold for the maturation process to materialize.
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Affiliation(s)
- Nibedita Lenka
- National Centre for Cell Science, Ganeshkhind, Pune, Maharashtra, India.
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14
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Stavridis MP, Lunn JS, Collins BJ, Storey KG. A discrete period of FGF-induced Erk1/2 signalling is required for vertebrate neural specification. Development 2007; 134:2889-94. [PMID: 17660197 DOI: 10.1242/dev.02858] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neural tissue formation is induced by growth factors that activate networks of signal transduction cascades that ultimately lead to the expression of early neural genes, including transcription factors of the SoxB family. Here, we report that fibroblast growth factor (FGF)-induced Erk1/2 (Mapk3 and Mapk1, respectively) mitogen-activated protein kinase (MAPK), but not phosphatidylinositol 3'-OH kinase (PI3K, Pik3r1), signalling is required for neural specification in mouse embryonic stem (ES) cells and in the chick embryo. Further, blocking Erk1/2 inhibits the onset of key SoxB genes in both mouse ES cells (Sox1) and chick embryos (Sox2 and Sox3) and, in both contexts, Erk1/2 signalling is required during only a narrow time window, as neural specification takes place. In the absence of Erk1/2 signalling, differentiation of ES cells stalls following Fgf5 upregulation. Using differentiating ES cells as a model for neural specification, we demonstrate that sustained Erk1/2 activation controls the transition from an Fgf5-positive, primitive ectoderm-like cell state to a neural progenitor cell state without attenuating bone morphogenetic protein (BMP) signalling and we also define the minimum period of Erk1/2 activity required to mediate this key developmental step. Together, these findings identify a conserved, specific and stage-dependent requirement for Erk1/2 signalling downstream of FGF-induced neural specification in higher vertebrates and provide insight into the signalling dynamics governing this process.
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Affiliation(s)
- Marios P Stavridis
- Division of Cell and Developmental Biology, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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15
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Varga M, Maegawa S, Bellipanni G, Weinberg ES. Chordin expression, mediated by Nodal and FGF signaling, is restricted by redundant function of two beta-catenins in the zebrafish embryo. Mech Dev 2007; 124:775-91. [PMID: 17686615 PMCID: PMC2156153 DOI: 10.1016/j.mod.2007.05.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 05/30/2007] [Accepted: 05/31/2007] [Indexed: 12/13/2022]
Abstract
Using embryos transgenic for the TOP-GFP reporter, we show that the two zebrafish beta-catenins have different roles in the organizer and germ-ring regions of the embryo. beta-Catenin-activated transcription in the prospective organizer region specifically requires beta-catenin-2, whereas the ventrolateral domain of activated transcription is abolished only when both beta-catenins are inhibited. chordin expression during zebrafish gastrulation has been previously shown in both axial and paraxial domains, but is excluded from ventrolateral domains. We show that this gene is expressed in paraxial territories adjacent to the domain of ventrolateral beta-catenin-activated transcription, with only slight overlap, consistent with the now well-known inhibitory effects of Wnt8 on dorsal gene expression. Eliminating both Wnt8/beta-catenin signaling and organizer activity by inhibition of expression of the two beta-catenins results in massive ectopic circumferential expression of chordin and later, by formation of a distinctive embryonic phenotype ('ciuffo') that expresses trunk and anterior neural markers with correct relative anteroposterior patterning. We show that chordin expression is required for this neural gene expression. The Nodal gene squint has been shown to be necessary for optimal expression of chordin and is sufficient in some contexts for its expression. However, chordin is not normally expressed in the ventrolateral germ-ring despite robust expression of squint in this domain. We show the ectopic circumferential expression of chordin and other dorsal genes to be completely dependent on Nodal and FGF signaling, and to be independent of a functional organizer. We propose that whereas the axial domain of chordin expression is formed by cells that are derived from the organizer, the paraxial domain is the result of axial-derived anti-Wnt signals, which relieve the repression that otherwise is set by the Wnt8/beta-catenin/vox,vent pathway on latent germ-ring Nodal/FGF-activated expression.
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Affiliation(s)
| | - Shingo Maegawa
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Eric S. Weinberg
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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16
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Bonnert TP, Bilsland JG, Guest PC, Heavens R, McLaren D, Dale C, Thakur M, McAllister G, Munoz-Sanjuan I. Molecular characterization of adult mouse subventricular zone progenitor cells during the onset of differentiation. Eur J Neurosci 2006; 24:661-75. [PMID: 16930398 DOI: 10.1111/j.1460-9568.2006.04912.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Adult mouse subventricular zone (SVZ) neural progenitor cells (NPCs) retain the capacity to generate multiple lineages in vitro and in vivo. Thus far, the mechanisms involved in the regulation of these cells have not been well elucidated. We have carried out RNA profiling of adult SVZ cell cultures undergoing differentiation, to identify pathways that regulate progenitor cell proliferation and to define a set of transcripts that can be used as molecular tools in the drug discovery process. We carried out a stepwise stratification of the results to identify transcripts specifically enriched in NPCs and validated some of these using comparative literature analysis, quantitative polymerase chain reaction and immunological techniques. The results show a set of transcription factors, secreted molecules and plasma membrane markers that are differentially regulated during differentiation. Pathway analysis highlights alterations in insulin growth factor, Wnt and transforming growth factor beta signalling cascades. Further characterization of these components could provide greater insight into the mechanisms involved in the regulation of neurogenesis in the adult brain.
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Affiliation(s)
- Timothy P Bonnert
- Molecular and Cellular Neuroscience Department, Merck Sharp & Dohme, The Neuroscience Research Centre, Terlings Park, Harlow, Essex CM20 2QR, UK
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17
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Magder S, Neculcea J, Neculcea V, Sladek R. Lipopolysaccharide and TNF-alpha produce very similar changes in gene expression in human endothelial cells. J Vasc Res 2006; 43:447-61. [PMID: 16921252 DOI: 10.1159/000095162] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 05/11/2006] [Indexed: 11/19/2022] Open
Abstract
Intracellular signaling pathways regulated by Toll-like receptor 4 (TLR4) and tumor necrosis factor-alpha (TNF-alpha) both activate NFkappaB. This suggests that lipopolysaccharide (LPS) and TNF-alpha should alter transcription of a common set of genes. We tested this hypothesis by treating first passage human umbilical endothelial cells (HUVEC) for 6 h with LPS (50 ng/ml+1 microg/ml CD14) or TNF-alpha (10 ng/ml) and analyzing changes in gene expression by microarray analysis (Affymetrix GeneChips). LPS and TNF-alpha increased expression of 191 common genes and decreased expression of 102 genes. Regulated transcripts encoded for a large number of chemokines, adhesion molecules, procoagulant factors, and molecules that affect cell integrity. Based on the microarray analysis and subsequent confirmation of specific genes by Northern analysis, all 203 genes altered by LPS were altered by TNF-alpha. An additional 17 genes were induced only by TNF-alpha and the expression of 46 was reduced. There were, however, some differences in the kinetics of changes. We also showed that endogenous CD14 was present on these early passage cells and exogenous CD14 was not necessary for most of the LPS response. An autocrine effect from LPS induced expression of TNF-alpha also was ruled out by blocking TNF-alpha with monoclonal antibodies. In conclusion, LPS induces a robust alteration in gene expression in HUVEC that is very similar to that induced by TNF-a. This LPS effect on endothelium could play an important role in the innate immune response.
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Affiliation(s)
- S Magder
- McGill University Health Centre, Royal Victoria Hospital, Montreal, Canada.
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18
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Matus DQ, Pang K, Marlow H, Dunn CW, Thomsen GH, Martindale MQ. Molecular evidence for deep evolutionary roots of bilaterality in animal development. Proc Natl Acad Sci U S A 2006; 103:11195-200. [PMID: 16837574 PMCID: PMC1544064 DOI: 10.1073/pnas.0601257103] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Indexed: 11/18/2022] Open
Abstract
Nearly all metazoans show signs of bilaterality, yet it is believed the bilaterians arose from radially symmetric forms hundreds of millions of years ago. Cnidarians (corals, sea anemones, and "jellyfish") diverged from other animals before the radiation of the Bilateria. They are diploblastic and are often characterized as being radially symmetrical around their longitudinal (oral-aboral) axis. We have studied the deployment of orthologs of a number of family members of developmental regulatory genes that are expressed asymmetrically during bilaterian embryogenesis from the sea anemone, Nematostella vectensis. The secreted TGF-beta genes Nv-dpp, Nv-BMP5-8, six TGF-beta antagonists (NvChordin, NvNoggin1, NvNoggin2, NvGremlin, NvFollistatin, and NvFollistatin-like), the homeodomain proteins NvGoosecoid (NvGsc) and NvGbx, and the secreted guidance factor, NvNetrin, were studied. NvDpp, NvChordin, NvNoggin1, NvGsc, and NvNetrin are expressed asymmetrically along the axis perpendicular to the oral-aboral axis, the directive axis. Furthermore, NvGbx, and NvChordin are expressed in restricted domains on the left and right sides of the body, suggesting that the directive axis is homologous with the bilaterian dorsal-ventral axis. The asymmetric expression of NvNoggin1 and NvGsc appear to be maintained by the canonical Wnt signaling pathway. The asymmetric expression of NvNoggin1, NvNetrin, and Hox orthologs NvAnthox7, NvAnthox8, NvAnthox1a, and NvAnthox6, in conjunction with the observation that NvNoggin1 is able to induce a secondary axis in Xenopus embryos argues that N. vectensis could possess antecedents of the organization of the bilaterian central nervous system.
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Affiliation(s)
- David Q. Matus
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Kevin Pang
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Heather Marlow
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Casey W. Dunn
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
| | - Gerald H. Thomsen
- Department of Biochemistry and Cell Biology, Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794-5215
| | - Mark Q. Martindale
- *Kewalo Marine Laboratory, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, HI 96813; and
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19
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Schlosser G. Induction and specification of cranial placodes. Dev Biol 2006; 294:303-51. [PMID: 16677629 DOI: 10.1016/j.ydbio.2006.03.009] [Citation(s) in RCA: 280] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 12/22/2005] [Accepted: 12/23/2005] [Indexed: 12/17/2022]
Abstract
Cranial placodes are specialized regions of the ectoderm, which give rise to various sensory ganglia and contribute to the pituitary gland and sensory organs of the vertebrate head. They include the adenohypophyseal, olfactory, lens, trigeminal, and profundal placodes, a series of epibranchial placodes, an otic placode, and a series of lateral line placodes. After a long period of neglect, recent years have seen a resurgence of interest in placode induction and specification. There is increasing evidence that all placodes despite their different developmental fates originate from a common panplacodal primordium around the neural plate. This common primordium is defined by the expression of transcription factors of the Six1/2, Six4/5, and Eya families, which later continue to be expressed in all placodes and appear to promote generic placodal properties such as proliferation, the capacity for morphogenetic movements, and neuronal differentiation. A large number of other transcription factors are expressed in subdomains of the panplacodal primordium and appear to contribute to the specification of particular subsets of placodes. This review first provides a brief overview of different cranial placodes and then synthesizes evidence for the common origin of all placodes from a panplacodal primordium. The role of various transcription factors for the development of the different placodes is addressed next, and it is discussed how individual placodes may be specified and compartmentalized within the panplacodal primordium. Finally, tissues and signals involved in placode induction are summarized with a special focus on induction of the panplacodal primordium itself (generic placode induction) and its relation to neural induction and neural crest induction. Integrating current data, new models of generic placode induction and of combinatorial placode specification are presented.
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Affiliation(s)
- Gerhard Schlosser
- Brain Research Institute, AG Roth, University of Bremen, FB2, 28334 Bremen, Germany.
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20
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Matus DQ, Thomsen GH, Martindale MQ. Dorso/ventral genes are asymmetrically expressed and involved in germ-layer demarcation during cnidarian gastrulation. Curr Biol 2006; 16:499-505. [PMID: 16527745 DOI: 10.1016/j.cub.2006.01.052] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 01/11/2006] [Accepted: 01/19/2006] [Indexed: 11/28/2022]
Abstract
Cnidarians (corals, sea anemones, hydroids, and jellyfish) are a basal taxon closely related to bilaterally symmetrical animals and have been characterized as diploblastic and as radially symmetrical around their longitudinal axis. We show that some orthologs of key bilaterian dorso/ventral (D/V) patterning genes, including the TGFbeta signaling molecules NvDpp and NvBMP5-8 and their antagonist NvChordin, are initially expressed asymmetrically at the onset of gastrulation in the anthozoan sea anemone Nematostella vectensis. Surprisingly, unlike flies and vertebrates, the TGFbeta ligands and their antagonist are colocalized at the onset of gastrulation but then segregate by germ layer as gastrulation proceeds. TGFbeta ligands, their extracellular enhancer, NvTolloid, and components of their downstream signaling pathway (NvSmad1/5 and NvSmad4) are all coexpressed in presumptive endoderm, indicating that only planar TGFbeta signaling operates at these stages. NvChordin expression forms a boundary between TGFbeta-expressing endodermal cells and aboral ectoderm. Manipulation of nuclear beta-catenin localization affects TGFbeta ligand and antagonist expression, suggesting that the ancestral role of the dpp/chordin antagonism during gastrulation may have been in germ-layer segregation and/or epithelial patterning rather than dorsal/ventral patterning.
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Affiliation(s)
- David Q Matus
- Kewalo Marine Lab, Pacific Bioscience Research Center, University of Hawaii, 41 Ahui Street, Honolulu, Hawaii 96813, USA
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21
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Kato T, Heike T, Okawa K, Haruyama M, Shiraishi K, Yoshimoto M, Nagato M, Shibata M, Kumada T, Yamanaka Y, Hattori H, Nakahata T. A neurosphere-derived factor, cystatin C, supports differentiation of ES cells into neural stem cells. Proc Natl Acad Sci U S A 2006; 103:6019-24. [PMID: 16595632 PMCID: PMC1458690 DOI: 10.1073/pnas.0509789103] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Indexed: 11/18/2022] Open
Abstract
Although embryonic stem (ES) cells are capable of unlimited proliferation and pluripotent differentiation, effective preparation of neural stem cells from ES cells are not achieved. Here, we have directly generated under the coculture with dissociated primary neurosphere cells in serum-free medium and the same effect was observed when ES cells were cultured with conditioned medium of primary neurosphere culture (CMPNC). ES-neural stem cells (NSCs) could proliferate for more than seven times and differentiate into neurons, astrocytes, and oligodendrocytes in vitro and in vivo. The responsible molecule in CMPNC was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, which turned out to be cystatin C. Purified cystatin C in place of the CMPNC could generate ES-NSCs efficiently with self-renewal and multidifferentiation potentials. These results reveal the validity of cystatin C for generating NSCs from ES cells.
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Affiliation(s)
| | | | - Katsuya Okawa
- Biomolecular Characterization Unit, Horizontal Medical Research Organization, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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22
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Schlosser G. Development and evolution of lateral line placodes in amphibians I. Development. ZOOLOGY 2006; 105:119-46. [PMID: 16351862 DOI: 10.1078/0944-2006-00058] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2002] [Accepted: 05/30/2002] [Indexed: 11/18/2022]
Abstract
Lateral line placodes are specialized regions of the ectoderm that give rise to the receptor organs of the lateral line system as well as to the sensory neurons innervating them. The development of lateral line placodes has been studied in amphibians since the early 1900s. This paper reviews these older studies and tries to integrate them with more recent findings. Lateral line placodes are probably induced in a multistep process from a panplacodal area surrounding the neural plate. The time schedule of these inductive processes has begun to be unravelled, but little is known yet about their molecular basis. Subsequent pattern formation, morphogenesis and differentiation of lateral line placodes proceeds in most respects relatively autonomously: Onset and polarity of migration of lateral line primordia, the type, spacing, size and number of receptor organs formed, as well as the patterned differentiation of different cell types occur normally even in ectopic locations. Only the pathways for migration of lateral line primordia depend on external cues. Thus, lateral line placodes act as integrated and relatively context-insensitive developmental modules.
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23
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Abstract
The prevailing approach within the field of craniofacial development is focused on finding a balance between tissues (e.g., facial epithelia, neuroectoderm, and neural crest) and molecules (e.g., bone morphogenetic proteins, fibroblast growth factors, Wnts) that play a role in sculpting the face. We are rapidly learning that neither these tissues nor molecular signals are able to act in isolation; in fact, molecular cues are constantly reciprocating signals between the epithelia and the neural crest in order to pattern and mold facial structures. More recently, it has been proposed that this crosstalk is often mediated and organized by discrete organizing centers within the tissues that are able to act as a self-contained unit of developmental potential (e.g., the rhombomere and perhaps the ectomere). Whatever the molecules are and however they are interpreted by these tissues, it appears that there is a remarkably conserved mechanism for setting up the initial organization of the facial prominences between species. Regardless of species, all vertebrates appear to have the same basic bauplan. However, sometime during mid-gestation, the vertebrate face begins to exhibit species-specific variations, in large part due to differences in the rates of growth and differentiation of cells comprising the facial prominences. How do these differences arise? Are they due to late changes in molecular signaling within the facial prominences themselves? Or are these late changes a reflection of earlier, more subtle alterations in boundaries and fields that are established at the earliest stages of head formation? We do not have clear answers to these questions yet, but in this chapter we present new studies that shed light on this age-old question. This chapter aims to present the known signals, both on a molecular and cellular level, responsible for craniofacial development while bringing to light the events that may serve to create difference in facial morphology seen from species to species.
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Affiliation(s)
- Samantha A Brugmann
- Department of Plastic and Reconstructive Surgery, Stanford University, California 94305, USA
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24
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Takemoto T, Uchikawa M, Kamachi Y, Kondoh H. Convergence of Wnt and FGF signals in the genesis of posterior neural plate through activation of the Sox2 enhancer N-1. Development 2005; 133:297-306. [PMID: 16354715 DOI: 10.1242/dev.02196] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The expression of the transcription factor gene Sox2 precisely marks the neural plate in various vertebrate species. We previously showed that the Sox2 expression prevailing in the neural plate of chicken embryos is actually regulated by the coordination of five phylogenetically conserved enhancers having discrete regional coverage, among which the 420-bp long enhancer N-1, active in the node-proximal region, is probably involved directly in the genesis of the posterior neural plate. We investigated the signaling systems regulating this enhancer, first identifying the 56-bp N-1 core enhancer (N-1c), which in a trimeric form recapitulates the activity of the enhancer N-1. Mutational analysis identified five blocks, A to E, that regulate the enhancer N-1c. Functional analysis of these blocks indicated that Wnt and FGF signals synergistically activate the enhancer through Blocks A-B, bound by Lef1, and Block D, respectively. Fgf8b and Wnt8c expressed in the organizer-primitive streak region account for the activity in the embryo. Block E is essential for the repression of the enhancer N-1c activity in the mesendodermal precursors. The enhancer N-1c is not affected by BMP signals. Thus, Wnt and FGF signals converge to activate Sox2 expression through the enhancer N-1c, revealing the direct involvement of the Wnt signal in the initiation of neural plate development.
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Affiliation(s)
- Tatsuya Takemoto
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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25
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Deng J, Petersen BE, Steindler DA, Jorgensen ML, Laywell ED. Mesenchymal stem cells spontaneously express neural proteins in culture and are neurogenic after transplantation. Stem Cells 2005; 24:1054-64. [PMID: 16322639 DOI: 10.1634/stemcells.2005-0370] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Reports of neural transdifferentiation of mesenchymal stem cells (MSCs) suggest the possibility that these cells may serve as a source for stem cell-based regenerative medicine to treat neurological disorders. However, some recent studies controvert previous reports of MSC neurogenecity. In the current study, we evaluate the neural differentiation potential of mouse bone marrow-derived MSCs. Surprisingly, we found that MSCs spontaneously express certain neuronal phenotype markers in culture, in the absence of specialized induction reagents. A previously published neural induction protocol that elevates cytoplasmic cyclic AMP does not upregulate neuron-specific protein expression significantly in MSCs but does significantly increase expression of the astrocyte-specific glial fibrillary acidic protein. Finally, when grafted into the lateral ventricles of neonatal mouse brain, MSCs migrate extensively and differentiate into olfactory bulb granule cells and periventricular astrocytes, without evidence of cell fusion. These results indicate that MSCs may be "primed" toward a neural fate by the constitutive expression of neuronal antigens and that they seem to respond with an appropriate neural pattern of differentiation when exposed to the environment of the developing brain.
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Affiliation(s)
- Jie Deng
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, USA
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26
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Abstract
During neural induction, the embryonic neural plate is specified and set aside from other parts of the ectoderm. A popular molecular explanation is the 'default model' of neural induction, which proposes that ectodermal cells give rise to neural plate if they receive no signals at all, while BMP activity directs them to become epidermis. However, neural induction now appears to be more complex than once thought, and can no longer be fully explained by the default model alone. This review summarizes neural induction events in different species and highlights some unanswered questions about this important developmental process.
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Affiliation(s)
- Claudio D Stern
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.
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27
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Abstract
No region of our anatomy more powerfully conveys our emotions nor elicits more profound reactions when disease or genetic disorders disfigure it than the face. Recent progress has been made towards defining the tissue interactions and molecular mechanisms that control craniofacial morphogenesis. Some insights have come from genetic manipulations and others from tissue recombinations and biochemical approaches, which have revealed the molecular underpinnings of facial morphogenesis. Changes in craniofacial architecture also lie at the heart of evolutionary adaptation, as new studies in fish and fowl attest. Together, these findings reveal much about molecular and tissue interactions behind craniofacial development.
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Affiliation(s)
- Jill A Helms
- Department of Plastic and Reconstructive Surgery, Stanford University, Stanford, CA 94305, USA.
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28
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Abstract
We review the current status of research in dorsal-ventral (D-V) patterning in vertebrates. Emphasis is placed on recent work on Xenopus, which provides a paradigm for vertebrate development based on a rich heritage of experimental embryology. D-V patterning starts much earlier than previously thought, under the influence of a dorsal nuclear -Catenin signal. At mid-blastula two signaling centers are present on the dorsal side: The prospective neuroectoderm expresses bone morphogenetic protein (BMP) antagonists, and the future dorsal endoderm secretes Nodal-related mesoderm-inducing factors. When dorsal mesoderm is formed at gastrula, a cocktail of growth factor antagonists is secreted by the Spemann organizer and further patterns the embryo. A ventral gastrula signaling center opposes the actions of the dorsal organizer, and another set of secreted antagonists is produced ventrally under the control of BMP4. The early dorsal -Catenin signal inhibits BMP expression at the transcriptional level and promotes expression of secreted BMP antagonists in the prospective central nervous system (CNS). In the absence of mesoderm, expression of Chordin and Noggin in ectoderm is required for anterior CNS formation. FGF (fibroblast growth factor) and IGF (insulin-like growth factor) signals are also potent neural inducers. Neural induction by anti-BMPs such as Chordin requires mitogen-activated protein kinase (MAPK) activation mediated by FGF and IGF. These multiple signals can be integrated at the level of Smad1. Phosphorylation by BMP receptor stimulates Smad1 transcriptional activity, whereas phosphorylation by MAPK has the opposite effect. Neural tissue is formed only at very low levels of activity of BMP-transducing Smads, which require the combination of both low BMP levels and high MAPK signals. Many of the molecular players that regulate D-V patterning via regulation of BMP signaling have been conserved between Drosophila and the vertebrates.
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Affiliation(s)
- Edward M De Robertis
- Howard Hughes Medical Institute, Department of Biological Chemistry, University of California-Los Angeles, Los Angeles, CA 90095-1662, USA.
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29
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Linker C, Stern CD. Neural induction requires BMP inhibition only as a late step, and involves signals other than FGF and Wnt antagonists. Development 2005; 131:5671-81. [PMID: 15509767 DOI: 10.1242/dev.01445] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A dominant molecular explanation for neural induction is the 'default model', which proposes that the ectoderm is pre-programmed towards a neural fate, but is normally inhibited by endogenous BMPs. Although there is strong evidence favouring this in Xenopus, data from other organisms suggest more complexity, including an involvement of FGF and modulation of Wnt. However, it is generally believed that these additional signals also act by inhibiting BMPs. We have investigated whether BMP inhibition is necessary and/or sufficient for neural induction. In the chick, misexpression of BMP4 in the prospective neural plate inhibits the expression of definitive neural markers (Sox2 and late Sox3), but does not affect the early expression of Sox3, suggesting that BMP inhibition is required only as a late step during neural induction. Inhibition of BMP signalling by the potent antagonist Smad6, either alone or together with a dominant-negative BMP receptor, Chordin and/or Noggin in competent epiblast is not sufficient to induce expression of Sox2 directly, even in combination with FGF2, FGF3, FGF4 or FGF8 and/or antagonists of Wnt signalling. These results strongly suggest that BMP inhibition is not sufficient for neural induction in the chick embryo. To test this in Xenopus, Smad6 mRNA was injected into the A4 blastomere (which reliably contributes to epidermis but not to neural plate or its border) at the 32-cell stage: expression of neural markers (Sox3 and NCAM) is not induced. We propose that neural induction involves additional signalling events that remain to be identified.
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Affiliation(s)
- Claudia Linker
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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30
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Pera MF, Andrade J, Houssami S, Reubinoff B, Trounson A, Stanley EG, Ward-van Oostwaard D, Mummery C. Regulation of human embryonic stem cell differentiation by BMP-2 and its antagonist noggin. J Cell Sci 2004; 117:1269-80. [PMID: 14996946 DOI: 10.1242/jcs.00970] [Citation(s) in RCA: 367] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human embryonic stem cells differentiate spontaneously in vitro into a range of cell types, and they frequently give rise to cells with the properties of extra-embryonic endoderm. We show here that endogenous signaling by bone morphogenetic protein-2 controls the differentiation of embryonic stem cells into this lineage. Treatment of embryonic stem cell cultures with the bone morphogenetic protein antagonist noggin blocks this form of differentiation and induces the appearance of a novel cell type that can give rise to neural precursors. These findings indicate that bone morphogenetic protein-2 controls a key early commitment step in human embryonic stem cell differentiation, and show that the conservation of developmental mechanisms at the cellular level can be exploited in this system--in this case, to provide a facile route for the generation of neural precursors from pluripotent cells.
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Affiliation(s)
- Martin F Pera
- Monash Institute of Reproduction and Development, Monash University, 246 Clayton Road, Clayton, Victoria 3168, Australia.
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31
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Fürthauer M, Van Celst J, Thisse C, Thisse B. Fgf signalling controls the dorsoventral patterning of the zebrafish embryo. Development 2004; 131:2853-64. [PMID: 15151985 DOI: 10.1242/dev.01156] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The establishment of dorsoventral (DV) patterning in vertebrate embryos depends on the morphogenic activity of a group of Tgfβ superfamily members, the bone morphogenetic proteins (Bmps) (which specify ventral cell fates), and on their interaction with their dorsally secreted cognate inhibitors chordin and noggin. In the zebrafish, genetic analysis has revealed that Bmp2b and Bmp7, as well as their antagonist chordin, are required for proper DV patterning. The expression of Bmp genes is initially activated in the whole blastula. Well before the beginning of gastrulation, Bmp gene expression progressively disappears from the dorsal side to become restricted to the ventral part of the embryo. We show that this early restriction of Bmp gene expression, which occurs independently of noggin and chordin, is an essential step in the establishment of DV patterning. The progressive ventral restriction of Bmp gene transcripts is coincident with the spreading of Fgf activity from the dorsal side of the embryo, suggesting that Fgf signalling is implicated in dorsal downregulation of Bmp gene expression. In accordance with this, activation of the Fgf/Ras/Mapk-signalling pathway inhibits ventral Bmp gene expression, thereby causing a dorsalisation of the embryo. Conversely,inhibition of Fgf signalling causes Bmp gene expression to expand dorsally,leading to an expansion of ventral cell fates. In accordance with an important role of Fgf signalling in the DV patterning of the zebrafish, we show that loss of Fgf8 function enhances the ventralisation of chordin-deficient embryos. Our results thereby demonstrate that pre-gastrula stage Fgf-signalling is essential to delimit the expression domain of the genes encoding the functional morphogen of the dorsoventral axis of the early zebrafish embryo.
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Affiliation(s)
- Maximilian Fürthauer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR 7104, CNRS/INSERM/ULP, 1 rue Laurent Fries, BP10142, CU de Strasbourg, 67404, Illkirch Cedex, France
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32
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Abstract
The current understanding of organizer formation and neural induction in vertebrate embryos is discussed
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Affiliation(s)
- Igor B Dawid
- Laboratory of Molecular Genetics at the National Institute of Child Health and Human Development, National Institutes of Health, in Bethesda, Maryland, USA.
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33
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Bertrand V, Hudson C, Caillol D, Popovici C, Lemaire P. Neural Tissue in Ascidian Embryos Is Induced by FGF9/16/20, Acting via a Combination of Maternal GATA and Ets Transcription Factors. Cell 2003; 115:615-27. [PMID: 14651852 DOI: 10.1016/s0092-8674(03)00928-0] [Citation(s) in RCA: 242] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In chordates, formation of neural tissue from ectodermal cells requires an induction. The molecular nature of the inducer remains controversial in vertebrates. Here, using the early neural marker Otx as an entry point, we dissected the neural induction pathway in the simple embryos of Ciona intestinalis. We first isolated the regulatory element driving Otx expression in the prospective neural tissue, showed that this element directly responds to FGF signaling and that FGF9/16/20 acts as an endogenous neural inducer. Binding site analysis and gene loss of function established that FGF9/16/20 induces neural tissue in the ectoderm via a synergy between two maternal response factors. Ets1/2 mediates general FGF responsiveness, while the restricted activity of GATAa targets the neural program to the ectoderm. Thus, our study identifies an endogenous FGF neural inducer and its early downstream gene cascade. It also reveals a role for GATA factors in FGF signaling.
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Affiliation(s)
- Vincent Bertrand
- Laboratoire de Génétique et Physiologie du Développement, IBDM, CNRS/INSERM, Université de la Méditerranée/AP de Marseille, Parc Scientifique de Luminy, Case 907, F-13288, Marseille Cedex 9, France.
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34
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Aubert J, Stavridis MP, Tweedie S, O'Reilly M, Vierlinger K, Li M, Ghazal P, Pratt T, Mason JO, Roy D, Smith A. Screening for mammalian neural genes via fluorescence-activated cell sorter purification of neural precursors from Sox1-gfp knock-in mice. Proc Natl Acad Sci U S A 2003; 100 Suppl 1:11836-41. [PMID: 12923295 PMCID: PMC304095 DOI: 10.1073/pnas.1734197100] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The transcription factor Sox1 is the earliest and most specific known marker for mammalian neural progenitors. During fetal development, Sox1 is expressed by proliferating progenitor cells throughout the central nervous system and in no tissue but the lens. We generated a reporter mouse line in which egfp is inserted into the Sox1 locus. Sox1GFP animals faithfully recapitulate the expression of the endogenous gene. We have used the GFP reporter to purify neuroepithelial cells by fluorescence-activated cell sorting from embryonic day 10.5 embryos. RNAs prepared from Sox1GFP+ and Sox1GFP- embryo cells were then used to perform a pilot screen of subtracted cDNAs prepared from differentiating embryonic stem cells and arrayed on a glass chip. Fifteen unique differentially expressed genes were identified, all previously associated with fetal or adult neural tissue. Whole mount in situ hybridization against two genes of previously unknown embryonic expression, Lrrn1 and Musashi2, confirmed the selectivity of this screen for early neuroectodermal markers.
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Affiliation(s)
- Jerome Aubert
- Institute for Stem Cell Research, University of Edinburgh, King's Buildings, West Mains Road, EH9 3JQ Edinburgh, Scotland
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35
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Abstract
Signaling between cells is a widely used mechanism by which cell fate and tissue patterning is determined in development. We review the mechanisms by which signaling between cells is regulated so that a cell receives the right amount of signal, at the right time, to achieve its intended developmental fate and position. In nearly all cases, we find that the supply of signal factor (ligand) is the limiting step in initiating a signaling process. Ligand supply is regulated by the transcription and localization of RNA, the spread of ligand from a source, and by inhibitors that operate at several different levels. We emphasize the different regulatory strategies that operate for threshold as opposed to concentration-dependent (morphogen) signaling. Threshold signaling is extensively regulated by feedback mechanisms. Morphogen signaling is regulated quantitatively by receptor loading and transduction flow.
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Affiliation(s)
- M Freeman
- MRC Molecular Biology Laboratory, Hills Road, Cambridge CB2 2QH, United Kingdom.
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36
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Brunelli S, Silva Casey E, Bell D, Harland R, Lovell-Badge R. Expression of Sox3 throughout the developing central nervous system is dependent on the combined action of discrete, evolutionarily conserved regulatory elements. Genesis 2003; 36:12-24. [PMID: 12748963 DOI: 10.1002/gene.10193] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
SOX3 is one of the earliest neural markers in vertebrates and is thought to play a role in specifying neuronal fate. To investigate the regulation of Sox3 expression we identified cis-regulatory regions in the Sox3 promoter that direct tissue-specific heterologous marker gene expression in transgenic mice. Our results show that an 8.3 kb fragment, comprising 3 kb upstream and 3 kb downstream of the Sox3 transcriptional unit, is sufficient in a lacZ reporter construct to reproduce most aspects of Sox3 expression during CNS development from headfold to midgestation stages. The apparently uniform expression of Sox3 in the neural tube depends, however, on the combined action of distinct regulatory modules within this 8.3 kb region. Each of these gives expression in a subdomain of the complete expression pattern. These are restricted along both the rostral-caudal and dorso-ventral axes and can be quite specific, one element giving expression largely confined to V2 interneuron precursors. We also find that at least some of the regulatory sequences are able to drive expression of the transgene in the CNS Xenopus laevis embryos in a manner that reflects the endogenous Sox3 expression pattern. These results imply that the underlying mechanism regulating early CNS patterning is conserved, despite several substantial differences in neurogenesis between mammals and amphibians.
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37
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Hager-Theodorides AL, Outram SV, Shah DK, Sacedon R, Shrimpton RE, Vicente A, Varas A, Crompton T. Bone morphogenetic protein 2/4 signaling regulates early thymocyte differentiation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:5496-504. [PMID: 12421925 DOI: 10.4049/jimmunol.169.10.5496] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Bone morphogenetic protein (BMP)2 and BMP4 are involved in the development of many tissues. In this study, we show that BMP2/4 signaling is involved in thymocyte development. Our data suggest that termination of BMP2/4 signaling is necessary for differentiation of CD44(+)CD25(-)CD4(-)CD8(-) double negative (DN) cells along the T cell lineage. BMP2 and BMP4 are produced by the thymic stroma and the requisite BMP receptor molecules (BMPR-1A, BMPR-1B, BMPR-II), and signal transduction molecules (Smad-1, -5, -8, and -4) are expressed by DN thymocytes. BMP4 inhibits thymocyte proliferation, enhances thymocyte survival, and arrests thymocyte differentiation at the CD44(+)CD25(-) DN stage, before T cell lineage commitment. Neutralization of endogenous BMP2 and BMP4 by treatment with the antagonist Noggin promotes and accelerates thymocyte differentiation, increasing the expression of CD2 and the proportion of CD44(-)CD25(-) DN cells and CD4(+)CD8(+) double-positive cells. Our study suggests that the BMP2/4 pathway may function in thymic homeostasis by regulating T cell lineage commitment and differentiation.
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MESH Headings
- Activin Receptors, Type I/biosynthesis
- Activin Receptors, Type I/genetics
- Adjuvants, Immunologic/pharmacology
- Adjuvants, Immunologic/physiology
- Animals
- Bone Morphogenetic Protein 2
- Bone Morphogenetic Protein 4
- Bone Morphogenetic Protein Receptors, Type I
- Bone Morphogenetic Proteins/antagonists & inhibitors
- Bone Morphogenetic Proteins/physiology
- Carrier Proteins
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Survival/genetics
- Cell Survival/immunology
- Cells, Cultured
- Dose-Response Relationship, Immunologic
- Fetus
- Gene Expression Regulation/immunology
- Genes, T-Cell Receptor beta/genetics
- Genes, T-Cell Receptor delta/genetics
- Growth Inhibitors/physiology
- Hyaluronan Receptors/biosynthesis
- Hyaluronan Receptors/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Organ Culture Techniques
- Protein Serine-Threonine Kinases
- Proteins/pharmacology
- Receptors, Growth Factor
- Receptors, Interleukin-2/biosynthesis
- Receptors, Interleukin-2/metabolism
- Recombinant Fusion Proteins/pharmacology
- Signal Transduction/genetics
- Signal Transduction/immunology
- T-Lymphocytes/cytology
- T-Lymphocytes/metabolism
- Thymus Gland/cytology
- Thymus Gland/metabolism
- Transforming Growth Factor beta
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38
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Charrier JB, Lapointe F, Le Douarin NM, Teillet MA. Dual origin of the floor plate in the avian embryo. Development 2002; 129:4785-96. [PMID: 12361970 DOI: 10.1242/dev.129.20.4785] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Molecular analysis carried out on quail-chick chimeras, in which quail Hensen’s node was substituted for its chick counterpart at the five- to six-somite stage (ss), showed that the floor plate of the avian neural tube is composed of distinct areas: (1) a median one (medial floor plate or MFP) derived from Hensen’s node and characterised by the same gene expression pattern as the node cells (i.e. expression of HNF3β and Shh to the exclusion of genes early expressed in the neural ectoderm such as CSox1); and (2) lateral regions that are differentiated from the neuralised ectoderm (CSox1 positive) and form the lateral floor plate (LFP). LFP cells are induced by the MFP to express HNF3β transiently, Shh continuously and other floor-plate characteristic genes such as Netrin. In contrast to MFP cells, LFP cells also express neural markers such as Nkx2.2 and Sim1. This pattern of avian floor-plate development presents some similarities to floor-plate formation in zebrafish embryos. We also demonstrate that, although MFP and LFP have different embryonic origins in normal development, one can experimentally obtain a complete floor plate in the neural epithelium by the inductive action of either a notochord or a MFP. The competence of the neuroepithelium to respond to notochord or MFP signals is restricted to a short time window, as only the posterior-most region of the neural plate of embryos younger than 15 ss is able to differentiate a complete floor plate comprising MFP and LFP. Moreover, MFP differentiation requires between 4 and 5 days of exposure to the inducing tissues. Under the same conditions LFP and SHH-producing cells only induce LFP-type cells. These results show that the capacity to induce a complete floor plate is restricted to node-derived tissues and probably involves a still unknown factor that is not SHH, the latter being able to induce only LFP characteristics in neuralised epithelium.
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Affiliation(s)
- Jean-Baptiste Charrier
- Institut d'Embryologie Cellulaire et Moléculaire, CNRS and Collège de France, UMR 7128, 49bis Avenue de la Belle Gabrielle, 94736 Nogent-sur-Marne Cedex, France
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39
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Stern CD. Induction and initial patterning of the nervous system - the chick embryo enters the scene. Curr Opin Genet Dev 2002; 12:447-51. [PMID: 12100891 DOI: 10.1016/s0959-437x(02)00324-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Until recently, almost everything known about the molecular controls of early neural development came from studies in amphibians. It is now possible to misexpress factors in chick embryos at relatively late stages in development, allowing careful dissection of the timing of cell interactions. This is starting to contribute significantly to our understanding of neural induction and early patterning.
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Affiliation(s)
- Claudio D Stern
- Department of Anatomy & Developmental Biology, University College London, UK.
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40
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Rusten TE, Cantera R, Kafatos FC, Barrio R. The role of TGFβ signaling in the formation of the dorsal nervous system is conserved betweenDrosophilaand chordates. Development 2002; 129:3575-84. [PMID: 12117808 DOI: 10.1242/dev.129.15.3575] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Transforming growth factor β signaling mediated by Decapentaplegic and Screw is known to be involved in defining the border of the ventral neurogenic region in the fruitfly. A second phase of Decapentaplegic signaling occurs in a broad dorsal ectodermal region. Here, we show that the dorsolateral peripheral nervous system forms within the region where this second phase of signaling occurs. Decapentaplegic activity is required for development of many of the dorsal and lateral peripheral nervous system neurons. Double mutant analysis of the Decapentaplegic signaling mediator Schnurri and the inhibitor Brinker indicates that formation of these neurons requires Decapentaplegic signaling, and their absence in the mutant is mediated by a counteracting repression by Brinker. Interestingly, the ventral peripheral neurons that form outside the Decapentaplegic signaling domain depend on Brinker to develop. The role of Decapentaplegic signaling on dorsal and lateral peripheral neurons is strikingly similar to the known role of Transforming growth factor β signaling in specifying dorsal cell fates of the lateral (later dorsal) nervous system in chordates (Halocythia, zebrafish, Xenopus, chicken and mouse). It points to an evolutionarily conserved mechanism specifying dorsal cell fates in the nervous system of both protostomes and deuterostomes.
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Affiliation(s)
- Tor Erik Rusten
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
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41
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Schubert FR, Mootoosamy RC, Walters EH, Graham A, Tumiotto L, Münsterberg AE, Lumsden A, Dietrich S. Wnt6 marks sites of epithelial transformations in the chick embryo. Mech Dev 2002; 114:143-8. [PMID: 12175501 DOI: 10.1016/s0925-4773(02)00039-4] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In a screen for Wnt genes executing the patterning function of the vertebrate surface ectoderm, we have isolated a novel chick Wnt gene, chick Wnt6. This gene encodes the first pan-epidermal Wnt signalling molecule. Further sites of expression are the boundary of the early neural plate and surface ectoderm, the roof of mesencephalon, pretectum and dorsal thalamus, the differentiating heart, and the otic vesicle. The precise sites of Wnt6 expression coincide with crucial changes in tissue architecture, namely epithelial remodelling and epithelial-mesenchymal transformation (EMT). Moreover, the expression of Wnt6 is closely associated with areas of Bmp signalling.
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Affiliation(s)
- Frank R Schubert
- MRC Centre for Developmental Neurobiology, King's College London, 4th Floor New Hunt's House, Guy's Campus, London SE1 1UL, UK
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42
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Rathjen J, Haines BP, Hudson KM, Nesci A, Dunn S, Rathjen PD. Directed differentiation of pluripotent cells to neural lineages: homogeneous formation and differentiation of a neurectoderm population. Development 2002; 129:2649-61. [PMID: 12015293 DOI: 10.1242/dev.129.11.2649] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During embryogenesis the central and peripheral nervous systems arise from a neural precursor population, neurectoderm, formed during gastrulation. We demonstrate the differentiation of mouse embryonic stem cells to neurectoderm in culture, in a manner which recapitulates embryogenesis, with the sequential and homogeneous formation of primitive ectoderm, neural plate and neural tube. Formation of neurectoderm occurs in the absence of extraembryonic endoderm or mesoderm and results in a stratified epithelium of cells with morphology, gene expression and differentiation potential consistent with positionally unspecified neural tube. Differentiation of this population to homogeneous populations of neural crest or glia was also achieved. Neurectoderm formation in culture allows elucidation of signals involved in neural specification and generation of implantable cell populations for therapeutic use.
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Affiliation(s)
- Joy Rathjen
- Department of Molecular Biosciences, The University of Adelaide, South Australia 5005, Australia
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43
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Luo T, Matsuo-Takasaki M, Thomas ML, Weeks DL, Sargent TD. Transcription factor AP-2 is an essential and direct regulator of epidermal development in Xenopus. Dev Biol 2002; 245:136-44. [PMID: 11969261 DOI: 10.1006/dbio.2002.0621] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Expression of the Xenopus homolog of the mammalian transcription factor AP-2alpha (XAP-2) is activated throughout the animal hemisphere shortly after the midblastula transition, and becomes restricted to prospective epidermis by the end of gastrulation, under the control of BMP signal modulation. Elevated expression in the future neural crest region begins at this time. Ectopic expression of XAP-2 can restore transcription of epidermal genes in neuralized ectoderm, both in ectodermal explants and in the intact embryo. Likewise, loss of XAP-2 function, accomplished by injection of antisense oligonucleotides or by overexpression of antimorphic XAP-2 derivatives, leads to loss of epidermal and gain of neural gene expression. These treatments also result in gastrulation failure. Thus, AP-2 is a critical regulator of ectodermal determination that is required for normal epidermal development and morphogenesis in the frog embryo.
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Affiliation(s)
- Ting Luo
- Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
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44
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Faure S, de Santa Barbara P, Roberts DJ, Whitman M. Endogenous patterns of BMP signaling during early chick development. Dev Biol 2002; 244:44-65. [PMID: 11900458 DOI: 10.1006/dbio.2002.0579] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Bone morphogenetic proteins (BMPs) are members of the transforming growth factor beta superfamily signaling molecules that play important roles in a wide variety of developmental processes. In this study, we have used an antibody specific for the phosphorylated and activated form of Smad1 to examine endogenous patterns of BMP signaling in chick embryos during early development. We find complex spatial and temporal distributions of BMP signaling that elucidate how BMPs may function in multiple patterning events in the early chick embryo. In the pregastrula embryo, we find that BMP signaling is initially ubiquitous and is extinguished in the epiblast at the onset of primitive streak formation. At the head process stage, BMP signaling is inactivated in prospective neural plate, while it is strongly activated at the neural plate border, a region which is populated by cells that will give rise to neural crest. During later development, we find a dynamic spatiotemporal activation of BMP signaling along the rostrocaudal axis, in the dorsal neural tube, in the notochord, and in the somites during their maturation process. We discuss the implication of our results for endogenous functions of BMP signaling during chick development.
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Affiliation(s)
- Sandrine Faure
- Department of Cell Biology, Massachusetts General Hospital, Boston, Massachusetts 02115, USA
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45
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Abstract
Neural induction constitutes the initial step in the generation of the vertebrate nervous system. In attempting to understand the principles that underlie this process, two key issues need to be resolved. When is neural induction initiated, and what is the cellular source and molecular nature of the neural inducing signal(s)? Currently, these aspects of neural induction seem to be very different in amphibian and amniote embryos. Here we highlight the similarities and the differences, and we propose a possible unifying mechanism.
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Affiliation(s)
- S I Wilson
- Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden
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46
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Abstract
Over the past decade, several molecules have been identified that influence neural cell fate in vertebrate embryos during gastrulation. The first neural inducers studied were proteins produced by dorsal mesoderm (the Spemann organizer); most of these proteins act by directly binding to and antagonizing the function of bone morphogenetic proteins (BMPs). Recent experiments have suggested that other secreted signals, such as Wnt and FGF, may neuralize ectoderm before organizer function by a different mechanism. Neural effector genes that mediate the response of ectoderm to secreted neuralizing signals have also been discovered. Interestingly, most of these newly identified neuralizing pathways continue the theme of BMP antagonism, but rather than antagonizing BMP protein function, they may neuralize tissue by suppressing Bmp expression. Down-regulation of Bmp expression in the prospective neural plate during gastrulation seems to be a shared feature of neural induction in vertebrate embryos. However, the signals used to accomplish this task seem to vary among vertebrates. Here, we will discuss the role of the recently identified secreted signals and neural effector genes in vertebrate neurogenesis.
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Affiliation(s)
- J J Bainter
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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47
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Abstract
Stem cells have offered much hope by promising to greatly extend the numbers and range of patients who could benefit from transplants, and to provide cell replacement therapy to treat debilitating diseases such as diabetes, Parkinson's and Huntington's disease. The issue of stem cell research is politically charged, prompting biologists to begin engaging in ethical debates, and generating in the general public an unusually high level of interest in this aspect of biology. But excitement notwithstanding, there is a long way to go in basic research before new therapies will be established, and now the pressure is on for scientists and clinicians to deliver.
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Affiliation(s)
- R Lovell-Badge
- Division of Developmental Genetics, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, UK.
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48
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Abstract
Cranial placodes are focal regions of thickened ectoderm in the head of vertebrate embryos that give rise to a wide variety of cell types, including elements of the paired sense organs and neurons in cranial sensory ganglia. They are essential for the formation of much of the cranial sensory nervous system. Although relatively neglected today, interest in placodes has recently been reawakened with the isolation of molecular markers for different stages in their development. This has enabled a more finely tuned approach to the understanding of placode induction and development and in some cases has resulted in the isolation of inducing molecules for particular placodes. Both morphological and molecular data support the existence of a preplacodal domain within the cranial neural plate border region. Nonetheless, multiple tissues and molecules (where known) are involved in placode induction, and each individual placode is induced at different times by a different combination of these tissues, consistent with their diverse fates. Spatiotemporal changes in competence are also important in placode induction. Here, we have tried to provide a comprehensive review that synthesises the highlights of a century of classical experimental research, together with more modern evidence for the tissues and molecules involved in the induction of each placode.
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Affiliation(s)
- C V Baker
- Division of Biology 139-74, California Institute of Technology, Pasadena, California, 91125, USA.
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49
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Altmann CR, Brivanlou AH. Neural patterning in the vertebrate embryo. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 203:447-82. [PMID: 11131523 DOI: 10.1016/s0074-7696(01)03013-3] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The embryonic central nervous system (CNS) is patterned along its antero-posterior, dorsal-ventral, and left-right axes. Along the dorsal-ventral axis, cell fate determination occurs during and following neural tube closure and involves the action of two opposing signaling pathways: SHH ventrally from the notochord and BMP/GDF dorsally from the boundary of neural and nonneural ectoderm and later from the roof plate. In addition, Wnt and retinoic acid signaling have been shown to act in dorsal-ventral patterning; however, their roles are understood in less detail. Along the antero-posterior axis, signals divide the neural tube into four major divisions: forebrain, midbrain, hindbrain, and spinal cord, and these differences can be detected soon after the formation of the neural plate. The FGF, Wnt, and retinoic acid signaling pathways have been implicated in the caudalization of neural tissue. Boundaries of Hox gene expression are observed along the anteroposterior axis and have been suggested to be involved in establishing different identities in the hindbrain and spinal cord. Complex gene expression patterns in the brain suggest the development of neuromeres dividing the brain into different regions that are elaborated further during development. Patterning along the left-right axis occurs concurrently with antero-posterior and dorsal-ventral patterning during gastrulation. A leading candidate for initiating asymmetry is activin, which acts through Nodal and Lefty before any morphological differences are observed. The big challenge will be understanding how these diverse signaling pathways interact both temporally and spatially to generate the complex adult nervous system.
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Affiliation(s)
- C R Altmann
- The Rockefeller University, New York, New York 10021, USA
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50
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Winkler C, Moon RT. Zebrafish mdk2, a novel secreted midkine, participates in posterior neurogenesis. Dev Biol 2001; 229:102-18. [PMID: 11133157 DOI: 10.1006/dbio.2000.9967] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Patterning the neural plate in vertebrates depends on complex interactions between a variety of secreted growth factors. Here we describe a novel secreted factor in zebrafish, named mdk2, related to the midkine family of heparin-binding growth factors that is involved in posterior neural development. mdk2 is expressed shortly after the onset of gastrulation in the presumptive neural plate cells of the epiblast, and this expression is enhanced by exogenous retinoic acid. Ectopic expression of mdk2 enhances neural crest cell fates at the lateral edges of the caudal neural plate, concomitant with a repression of anterior structures and mesendodermal and ectodermal markers. Reciprocally, ectopic expression of a dominant negative mdk2 results in severe deficiencies of structures posterior to the midbrain-hindbrain boundary, with negligible effects on anterior structures. In these embryos, the expression of hindbrain and neural crest markers is strongly reduced, and the formation of posterior primary moto- and sensory neurons is blocked. Analyses in mutant zebrafish embryos shows that expression of mdk2 is independent of FGF8 and nodal-related-1 signaling, but is under negative control of BMP signaling. These data support the hypothesis that mdk2 participates in posterior neural development in zebrafish.
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Affiliation(s)
- C Winkler
- Howard Hughes Medical Institute, Center for Developmental Biology, Seattle, Washington 98195-7750, USA
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