101
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Cseh B, Fernandez-Sauze S, Grall D, Schaub S, Doma E, Van Obberghen-Schilling E. Autocrine fibronectin directs matrix assembly and crosstalk between cell–matrix and cell–cell adhesion in vascular endothelial cells. J Cell Sci 2010; 123:3989-99. [DOI: 10.1242/jcs.073346] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cellular fibronectin (cFN) variants harboring extra FN type 3 repeats, namely extra domains B and A, are major constituents of the extracellular matrix around newly forming blood vessels during development and angiogenesis. Their expression is induced by angiogenic stimuli and their assembly into fibrillar arrays is driven by cell-generated tension at α5β1 integrin-based adhesions. Here, we examined the role and functional redundancy of cFN variants in cultured endothelial cells by isoform-selective RNA interference. We show that FN fibrillogenesis is a cell-autonomous process whereby basally directed secretion and assembly of cellular FN are tightly coupled events that play an important role not only in signaling at cell–matrix adhesions but also at cell–cell contacts. Silencing of cFN variants differentially affects integrin usage, cell spreading, motility and capillary morphogenesis in vitro. cFN-deficient cells undergo a switch from α5β1- to αvβ3-based adhesion, accompanied by a Src-regulated disruption of adherens junctions. These studies identify a crucial role for autocrine FN in subendothelial matrix assembly and junctional integrity that provides spatially and temporally restricted control of endothelial plasticity during angiogenic blood vessel remodeling.
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Affiliation(s)
- Botond Cseh
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Samantha Fernandez-Sauze
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Dominique Grall
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Sébastien Schaub
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Eszter Doma
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
| | - Ellen Van Obberghen-Schilling
- University of Nice-Sophia Antipolis, CNRS UMR 6543, Centre Antoine Lacassagne, 33 Avenue de Valombrose, 06189 Nice, France
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102
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Rallis C, Pinchin SM, Ish-Horowicz D. Cell-autonomous integrin control of Wnt and Notch signalling during somitogenesis. Development 2010; 137:3591-601. [DOI: 10.1242/dev.050070] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Integrins act at signalling crossroads, and their interactions with other signal transduction pathways are key to the regulation of normal and pathological cell cytoarchitecture and behaviour. Here, we describe a signalling cascade that acts during the formation of the defining segmental features of the vertebrate body – the somites – in which β1-integrin activity regulates epithelialisation by controlling downstream Wnt and Notch activity crucial for somite border formation. Using in vivo transcriptional inhibition in the developing chick embryo, we show that β1-integrin in the anterior presomitic mesoderm activates canonical Wnt signalling in a cell-autonomous, `outside-inside' manner. Signalling is mediated by integrin-linked kinase (ILK), leading to modulation of glycogen synthase kinase 3β (GSK3β) phosphorylation, and activates Notch signalling in the anterior presomitic mesoderm. The two signalling pathways then cooperate to promote somite formation via cMESO1/Mesp2. Our results show that β1-integrin can regulate cell shape and tissue morphogenesis indirectly, by regulation of downstream signalling cascades.
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Affiliation(s)
- Charalampos Rallis
- Developmental Genetics Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 4LY, UK
| | - Sheena M. Pinchin
- Developmental Genetics Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 4LY, UK
| | - David Ish-Horowicz
- Developmental Genetics Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 4LY, UK
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103
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Goody MF, Henry CA. Dynamic interactions between cells and their extracellular matrix mediate embryonic development. Mol Reprod Dev 2010; 77:475-88. [DOI: 10.1002/mrd.21157] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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104
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Krneta-Stankic V, Sabillo A, Domingo CR. Temporal and spatial patterning of axial myotome fibers in Xenopus laevis. Dev Dyn 2010; 239:1162-77. [PMID: 20235228 PMCID: PMC3086394 DOI: 10.1002/dvdy.22275] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Somites give rise to the vertebral column and segmented musculature of adult vertebrates. The cell movements that position cells within somites along the anteroposterior and dorsoventral axes are not well understood. Using a fate mapping approach, we show that at the onset of Xenopus laevis gastrulation, mesoderm cells undergo distinct cell movements to form myotome fibers positioned in discrete locations within somites and along the anteroposterior axis. We show that the distribution of presomitic cells along the anteroposterior axis is influenced by convergent and extension movements of the notochord. Heterochronic and heterotopic transplantations between presomitic gastrula and early tail bud stages show that these cells are interchangeable and can form myotome fibers in locations determined by the host embryo. However, additional transplantation experiments revealed differences in the competency of presomitic cells to form myotome fibers, suggesting that maturation within the tail bud presomitic mesoderm is required for myotome fiber differentiation.
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Affiliation(s)
| | - Armbien Sabillo
- Department of Biology, San Francisco State University, San Francisco, CA, 94132
| | - Carmen R. Domingo
- Department of Biology, San Francisco State University, San Francisco, CA, 94132
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105
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Tsuda S, Kitagawa T, Takashima S, Asakawa S, Shimizu N, Mitani H, Shima A, Tsutsumi M, Hori H, Naruse K, Ishikawa Y, Takeda H. FAK-mediated extracellular signals are essential for interkinetic nuclear migration and planar divisions in the neuroepithelium. J Cell Sci 2010; 123:484-96. [PMID: 20067997 DOI: 10.1242/jcs.057851] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
During the development of the vertebrate nervous system, mitosis of neural progenitor cells takes place near the lumen, the apical side of the neural tube, through a characteristic movement of nuclei known as interkinetic nuclear migration (INM). Furthermore, during the proliferative period, neural progenitor cells exhibit planar cell divisions to produce equivalent daughter cells. Here, we examine the potential role of extracellular signals in INM and planar divisions using the medaka mutant tacobo (tab). This tab mutant shows pleiotropic phenotypes, including neurogenesis, and positional cloning identified tab as laminin gamma1 (lamc1), providing a unique framework to study the role of extracellular signals in neurogenesis. In tab mutant neural tubes, a number of nuclei exhibit abnormal patterns of migration leading to basally mislocalized mitosis. Furthermore, the orientation of cell division near the apical surface is randomized. Probably because of these defects, neurogenesis is accelerated in the tab neural tube. Detailed analyses demonstrate that extracellular signals mediated by the FAK pathway regulate INM and planar divisions in the neuroepithelium, possibly through interaction with the intracellular dynein-motor system.
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Affiliation(s)
- Sachiko Tsuda
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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106
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Kii I, Nishiyama T, Li M, Matsumoto KI, Saito M, Amizuka N, Kudo A. Incorporation of tenascin-C into the extracellular matrix by periostin underlies an extracellular meshwork architecture. J Biol Chem 2009; 285:2028-39. [PMID: 19887451 DOI: 10.1074/jbc.m109.051961] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Extracellular matrix (ECM) underlies a complicated multicellular architecture that is subjected to significant forces from mechanical environment. Although various components of the ECM have been enumerated, mechanisms that evolve the sophisticated ECM architecture remain to be addressed. Here we show that periostin, a matricellular protein, promotes incorporation of tenascin-C into the ECM and organizes a meshwork architecture of the ECM. We found that both periostin null mice and tenascin-C null mice exhibited a similar phenotype, confined tibial periostitis, which possibly corresponds to medial tibial stress syndrome in human sports injuries. Periostin possessed adjacent domains that bind to tenascin-C and the other ECM protein: fibronectin and type I collagen, respectively. These adjacent domains functioned as a bridge between tenascin-C and the ECM, which increased deposition of tenascin-C on the ECM. The deposition of hexabrachions of tenascin-C may stabilize bifurcations of the ECM fibrils, which is integrated into the extracellular meshwork architecture. This study suggests a role for periostin in adaptation of the ECM architecture in the mechanical environment.
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Affiliation(s)
- Isao Kii
- Department of Biological Information, Tokyo Institute of Technology, 4259 Midori-ku, Nagatsuta, Yokohama 226-8501
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107
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Arrington CB, Yost HJ. Extra-embryonic syndecan 2 regulates organ primordia migration and fibrillogenesis throughout the zebrafish embryo. Development 2009; 136:3143-52. [PMID: 19700618 DOI: 10.1242/dev.031492] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
One of the first steps in zebrafish heart and gut organogenesis is the migration of bilateral primordia to the midline to form cardiac and gut tubes. The mechanisms that regulate this process are poorly understood. Here we show that the proteoglycan syndecan 2 (Sdc2) expressed in the extra-embryonic yolk syncytial layer (YSL) acts locally at the YSL-embryo interface to direct organ primordia migration, and is required for fibronectin and laminin matrix assembly throughout the embryo. Surprisingly, neither endogenous nor exogenous sdc2 expressed in embryonic cells can compensate for knockdown of sdc2 in the YSL, indicating that Sdc2 expressed in extra-embryonic tissues is functionally distinct from Sdc2 in embryonic cells. The effects of sdc2 knockdown in the YSL can be rescued by extra-embryonic Sdc2 lacking an extracellular proteolytic cleavage (shedding) site, but not by extra-embryonic Sdc2 lacking extracellular glycosaminoglycan (GAG) addition sites, suggesting that distinct GAG chains on extra-embryonic Sdc2 regulate extracellular matrix assembly, cell migration and epithelial morphogenesis of multiple organ systems throughout the embryo.
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Affiliation(s)
- Cammon B Arrington
- Division of Pediatric Cardiology, University of Utah, Salt Lake City, UT 84112, USA
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108
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Latimer A, Jessen JR. Extracellular matrix assembly and organization during zebrafish gastrulation. Matrix Biol 2009; 29:89-96. [PMID: 19840849 DOI: 10.1016/j.matbio.2009.10.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 10/08/2009] [Accepted: 10/08/2009] [Indexed: 01/31/2023]
Abstract
Zebrafish gastrulation entails morphogenetic cell movements that shape the body plan and give rise to an embryo with defined anterior-posterior and dorsal-ventral axes. Regulating these cell movements are diverse signaling pathways and proteins including Wnts, Src-family tyrosine kinases, cadherins, and matrix metalloproteinases. While our knowledge of how these proteins impact cell polarity and migration has advanced considerably in the last decade, almost no data exist regarding the organization of extracellular matrix (ECM) during zebrafish gastrulation. Here, we describe for the first time the assembly of a fibronectin (FN) and laminin containing ECM in the early zebrafish embryo. This matrix was first detected at early gastrulation (65% epiboly) in the form of punctae that localize to tissue boundaries separating germ layers from each other and the underlying yolk cell. Fibrillogenesis increased after mid-gastrulation (80% epiboly) coinciding with the period of planar cell polarity pathway-dependent convergence and extension cell movements. We demonstrate that FN fibrils present beneath deep mesodermal cells are aligned in the direction of membrane protrusion formation. Utilizing antisense morpholino oligonucleotides, we further show that knockdown of FN expression causes a convergence and extension defect. Taken together, our data show that similar to amphibian embryos, the formation of ECM in the zebrafish gastrula is a dynamic process that occurs in parallel to at least a portion of the polarized cell behaviors shaping the embryonic body plan. These results provide a framework for uncovering the interrelationship between ECM structure and cellular processes regulating convergence and extension such as directed migration and mediolateral/radial intercalation.
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Affiliation(s)
- Andrew Latimer
- Department of Medicine/Division of Genetic Medicine and the Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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109
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Martins GG, Rifes P, Amândio R, Rodrigues G, Palmeirim I, Thorsteinsdóttir S. Dynamic 3D cell rearrangements guided by a fibronectin matrix underlie somitogenesis. PLoS One 2009; 4:e7429. [PMID: 19829711 PMCID: PMC2759537 DOI: 10.1371/journal.pone.0007429] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2009] [Accepted: 09/16/2009] [Indexed: 12/26/2022] Open
Abstract
Somites are transient segments formed in a rostro-caudal progression during vertebrate development. In chick embryos, segmentation of a new pair of somites occurs every 90 minutes and involves a mesenchyme-to-epithelium transition of cells from the presomitic mesoderm. Little is known about the cellular rearrangements involved, and, although it is known that the fibronectin extracellular matrix is required, its actual role remains elusive. Using 3D and 4D imaging of somite formation we discovered that somitogenesis consists of a complex choreography of individual cell movements. Epithelialization starts medially with the formation of a transient epithelium of cuboidal cells, followed by cell elongation and reorganization into a pseudostratified epithelium of spindle-shaped epitheloid cells. Mesenchymal cells are then recruited to this medial epithelium through accretion, a phenomenon that spreads to all sides, except the lateral side of the forming somite, which epithelializes by cell elongation and intercalation. Surprisingly, an important contribution to the somite epithelium also comes from the continuous egression of mesenchymal cells from the core into the epithelium via its apical side. Inhibition of fibronectin matrix assembly first slows down the rate, and then halts somite formation, without affecting pseudopodial activity or cell body movements. Rather, cell elongation, centripetal alignment, N-cadherin polarization and egression are impaired, showing that the fibronectin matrix plays a role in polarizing and guiding the exploratory behavior of somitic cells. To our knowledge, this is the first 4D in vivo recording of a full mesenchyme-to-epithelium transition. This approach brought new insights into this event and highlighted the importance of the extracellular matrix as a guiding cue during morphogenesis.
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Affiliation(s)
- Gabriel G. Martins
- Centro de Biologia Ambiental, Departamento de Biologia Animal Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- * E-mail: (GGM); (ST)
| | - Pedro Rifes
- Centro de Biologia Ambiental, Departamento de Biologia Animal Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Rita Amândio
- Centro de Biologia Ambiental, Departamento de Biologia Animal Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Gabriela Rodrigues
- Centro de Biologia Ambiental, Departamento de Biologia Animal Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Isabel Palmeirim
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Sólveig Thorsteinsdóttir
- Centro de Biologia Ambiental, Departamento de Biologia Animal Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- * E-mail: (GGM); (ST)
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110
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Hidalgo M, Sirour C, Bello V, Moreau N, Beaudry M, Darribère T. In vivo analyzes of dystroglycan function during somitogenesis in Xenopus laevis. Dev Dyn 2009; 238:1332-45. [PMID: 19086027 DOI: 10.1002/dvdy.21814] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Dystroglycan (Dg) is a cell adhesion receptor for laminin that has been reported to play a role in skeletal muscle cell stability, cytoskeletal organization, cell polarity, and signaling. Here we show that Dg is expressed at both the notochord/somite and the intersomitic boundaries, where laminin and fibronectin are accumulated during somitogenesis. Inhibition of Dg function with morpholino antisense oligonucleotides or a dominant negative mutant results in the normal segmentation of the presomitic mesoderm but affects the number, the size, and the integrity of somites. Depletion of Dg disrupts proliferation and alignment of myoblasts without affecting XMyoD and XMRF4 expression. It also leads to defects in laminin deposition at the intersomitic junctions, whereas expression of integrin beta1 subunits and fibronectin assembly occur normally. Our results show that Dg is critical for both proliferation and elongation of somitic cells and that the Dg-cytoplasmic domain is required for the laminin assembly at the intersomitic boundaries. Developmental Dynamics 238:1332-1345, 2009. (c) 2008 Wiley-Liss, Inc.
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Affiliation(s)
- Magdalena Hidalgo
- Université Pierre et Marie Curie Paris 6 UMR CNRS 7622, Laboratoire de Biologie du Développement, équipe Matrice Extracellulaire et Développement, Paris, France
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111
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Jülich D, Mould AP, Koper E, Holley SA. Control of extracellular matrix assembly along tissue boundaries via Integrin and Eph/Ephrin signaling. Development 2009; 136:2913-21. [PMID: 19641014 DOI: 10.1242/dev.038935] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Extracellular matrixes (ECMs) coat and subdivide animal tissues, but it is unclear how ECM formation is restricted to tissue surfaces and specific cell interfaces. During zebrafish somite morphogenesis, segmental assembly of an ECM composed of Fibronectin (FN) depends on the FN receptor Integrin alpha5beta1. Using in vivo imaging and genetic mosaics, our studies suggest that incipient Itgalpha5 clustering along the nascent border precedes matrix formation and is independent of FN binding. Integrin clustering can be initiated by Eph/Ephrin signaling, with Ephrin reverse signaling being sufficient for clustering. Prior to activation, Itgalpha5 expressed on adjacent cells reciprocally and non-cell-autonomously inhibits spontaneous Integrin clustering and assembly of an ECM. Surface derepression of this inhibition provides a self-organizing mechanism for the formation and maintenance of ECM along the tissue surface. Within the tissue, interplay between Eph/Ephrin signaling, ligand-independent Integrin clustering and reciprocal Integrin inhibition restricts de novo ECM production to somite boundaries.
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Affiliation(s)
- Dörthe Jülich
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
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112
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Lee HS, Daar IO. EphrinB reverse signaling in cell-cell adhesion: is it just par for the course? Cell Adh Migr 2009; 3:250-5. [PMID: 19276658 DOI: 10.4161/cam.3.3.8211] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Cell-cell adhesion is a critical process for the formation and maintenance of tissue patterns during development, as well as invasion and metastasis of cancer cells. Although great strides have been made regarding our understanding of the processes that play a role in cell-cell adhesion, the precise mechanisms by which diverse signaling events regulate cell and tissue architecture is poorly understood. In this commentary we will focus on the Eph/ephrin signaling system, and specifically how the ephrinB1 transmembrane ligand for Eph receptor tyrosine kinases sends signals affecting cell-cell junctions. In a recent study using the epithelial cells of early stage Xenopus embryos, we have shown that loss- or gain-of function of ephrinB1 can disrupt cell-cell contacts and tight junctions. This study reveals a mechanism where ephrinB1 competes with active Cdc42 for binding to Par-6, a scaffold protein central to the Par polarity complex (Par-3/Par-6/Cdc42/aPKC) and disrupts the localization of tight junction-associated proteins (ZO-1, Cingulin) at tight junctions. This competition reduces aPKC activity critical to maintaining and/or forming tight junctions. Finally, phosphorylation of ephrinB1 on specific tyrosine residues can block the interaction between ephrinB1 and Par-6 at tight junctions, and restore tight junction formation. Recent evidence indicates that de-regulation of forward signaling through EphB receptors may play a role in metastatic progression in colon cancer. In light of the new data showing an effect of ephrinB reverse signaling on tight junctions, an additional mechanism can be hypothesized where de-regulation of ephrinB1 expression or phosphorylation may also impact metastatic progression.
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Affiliation(s)
- Hyun-Shik Lee
- Laboratory of Cell and Developmental Signaling, National Cancer Institute-Frederick, Frederick, MD 21702, USA
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113
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EphrinB reverse signaling contributes to endothelial and mural cell assembly into vascular structures. Blood 2009; 114:1707-16. [PMID: 19411631 DOI: 10.1182/blood-2008-12-192294] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
EphrinB transmembrane ligands and their cognate EphB receptor tyrosine kinases regulate vascular development through bidirectional cell-to-cell signaling, but little is known about the role of EphrinB during postnatal vascular remodeling. We report that EphrinB is a critical mediator of postnatal pericyte-to-endothelial cell assembly into vascular structures. This function is dependent upon extracellular matrix-supported cell-to-cell contact, engagement of EphrinB by EphB receptors expressed on another cell, and Src-dependent phosphorylation of the intracytoplasmic domain of EphrinB. Phosphorylated EphrinB marks angiogenic blood vessels in the developing and hypoxic retina, the wounded skin, and tumor tissue, and is detected at contact points between endothelial cells and pericytes. Furthermore, inhibition ofEphrinB activity prevents proper assembly of pericytes and endothelial cells into vascular structures. These results reveal a role for EphrinB signaling in orchestrating pericyte/endothelial cell assembly, and suggest that therapeutic targeting of EphrinB may prove useful for disrupting angiogenesis when it contributes to disease.
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114
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Chong SW, Korzh V, Jiang YJ. Myogenesis and molecules - insights from zebrafish Danio rerio. JOURNAL OF FISH BIOLOGY 2009; 74:1693-1755. [PMID: 20735668 DOI: 10.1111/j.1095-8649.2009.02174.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Myogenesis is a fundamental process governing the formation of muscle in multicellular organisms. Recent studies in zebrafish Danio rerio have described the molecular events occurring during embryonic morphogenesis and have thus greatly clarified this process, helping to distinguish between the events that give rise to fast v. slow muscle. Coupled with the well-known Hedgehog signalling cascade and a wide variety of cellular processes during early development, the continual research on D. rerio slow muscle precursors has provided novel insights into their cellular behaviours in this organism. Similarly, analyses on fast muscle precursors have provided knowledge of the behaviour of a sub-set of epitheloid cells residing in the anterior domain of somites. Additionally, the findings by various groups on the roles of several molecules in somitic myogenesis have been clarified in the past year. In this study, the authors briefly review the current trends in the field of research of D. rerio trunk myogenesis.
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Affiliation(s)
- S-W Chong
- Laboratory of Developmental Signalling and Patterning, Genes and Development Division, A STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore.
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115
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Kemp HA, Cooke JE, Moens CB. EphA4 and EfnB2a maintain rhombomere coherence by independently regulating intercalation of progenitor cells in the zebrafish neural keel. Dev Biol 2009; 327:313-26. [PMID: 19135438 PMCID: PMC2861865 DOI: 10.1016/j.ydbio.2008.12.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 12/06/2008] [Accepted: 12/10/2008] [Indexed: 10/21/2022]
Abstract
During vertebrate development, the hindbrain is transiently segmented into 7 distinct rhombomeres (r). Hindbrain segmentation takes place within the context of the complex morphogenesis required for neurulation, which in zebrafish involves a characteristic cross-midline division that distributes progenitor cells bilaterally in the forming neural tube. The Eph receptor tyrosine kinase EphA4 and the membrane-bound Ephrin (Efn) ligand EfnB2a, which are expressed in complementary segments in the early hindbrain, are required for rhombomere boundary formation. We showed previously that EphA4 promotes cell-cell affinity within r3 and r5, and proposed that preferential adhesion within rhombomeres contributes to boundary formation. Here we show that EfnB2a is similarly required in r4 for normal cell affinity and that EphA4 and EfnB2a regulate cell affinity independently within their respective rhombomeres. Live imaging of cell sorting in mosaic embryos shows that both proteins function during cross-midline cell divisions in the hindbrain neural keel. Consistent with this, mosaic EfnB2a over-expression causes widespread cell sorting and disrupts hindbrain organization, but only if induced at or before neural keel stage. We propose a model in which Eph and Efn-dependent cell affinity within rhombomeres serve to maintain rhombomere organization during the potentially disruptive process of teleost neurulation.
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Affiliation(s)
- Hilary A Kemp
- HHMI and Division of Basic Science, Fred Hutchinson Cancer Research Center B2-152, 1100 Fairview Ave. N., Seattle WA 98109, P.O. Box 19024 Summit plc, 91 Milton Park, Abingdon, Oxfordshire, OX14 4RY, UK
| | - Julie E Cooke
- HHMI and Division of Basic Science, Fred Hutchinson Cancer Research Center B2-152, 1100 Fairview Ave. N., Seattle WA 98109, P.O. Box 19024 Summit plc, 91 Milton Park, Abingdon, Oxfordshire, OX14 4RY, UK
| | - Cecilia B Moens
- HHMI and Division of Basic Science, Fred Hutchinson Cancer Research Center B2-152, 1100 Fairview Ave. N., Seattle WA 98109, P.O. Box 19024 Summit plc, 91 Milton Park, Abingdon, Oxfordshire, OX14 4RY, UK
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116
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Abstract
Fibronectin is an extracellular matrix protein found only in vertebrate organisms containing endothelium-lined vasculature and is required for cardiovascular development in fish and mice. Fibronectin and its splice variants containing EIIIA and EIIIB domains are highly upregulated around newly developing vasculature during embryogenesis and in pathological conditions including atherosclerosis, cardiac hypertrophy, and tumorigenesis. However, their molecular roles in these processes are not entirely understood. We review genetic studies examining functions of fibronectin and its splice variants during embryonic cardiovascular development, and discuss potential roles of fibronectin in vascular disease and tumor angiogenesis.
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Affiliation(s)
- Sophie Astrof
- Greenberg Division of Cardiology, Department of Medicine, Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, NY 10065, USA, tel: 01-212-746-7654, fax: 01-212-746-6669,
| | - Richard O. Hynes
- Howard Hughes Medical Institute, Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA 02139 USA, tel: 01-617-253-6422, fax: 01-617-253-8357,
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117
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Integrins during evolution: evolutionary trees and model organisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:779-89. [PMID: 19161977 DOI: 10.1016/j.bbamem.2008.12.013] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 12/03/2008] [Accepted: 12/23/2008] [Indexed: 11/23/2022]
Abstract
The integrins form a large family of cell adhesion receptors. All multicellular animals express integrins, indicating that the family evolved relatively early in the history of metazoans, and homologous sequences of the component domains of integrin alpha and beta subunits are seen in prokaryotes. Some integrins, however, seem to be much younger. For example, the alphaI domain containing integrins, including collagen receptors and leukocyte integrins, have been found in chordates only. Here, we will discuss what conclusions can be drawn about integrin function by studying the evolutionary conservation of integrins. We will also look at how studying integrins in organisms such as the fruit fly and mouse has helped our understanding of integrin evolution-function relationships. As an illustration of this, we will summarize the current understanding of integrin involvement in skeletal muscle formation.
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118
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Snow CJ, Henry CA. Dynamic formation of microenvironments at the myotendinous junction correlates with muscle fiber morphogenesis in zebrafish. Gene Expr Patterns 2009; 9:37-42. [PMID: 18783736 PMCID: PMC2655214 DOI: 10.1016/j.gep.2008.08.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 08/07/2008] [Accepted: 08/17/2008] [Indexed: 10/21/2022]
Abstract
Muscle development involves the specification and morphogenesis of muscle fibers that attach to tendons. After attachment, muscles and tendons then function as an integrated unit to transduce force to the skeletal system and stabilize joints. The attachment site is the myotendinous junction, or MTJ, and is the primary site of force transmission. We find that attachment of fast-twitch myofibers to the MTJ correlates with the formation of novel microenvironments within the MTJ. The expression or activation of two proteins involved in anchoring the intracellular cytoskeleton to the extracellular matrix, Focal adhesion kinase (Fak) and beta-dystroglycan is up-regulated. Conversely, the extracellular matrix protein Fibronectin (Fn) is down-regulated. This degradation of Fn as fast-twitch fibers attach to the MTJ results in Fn protein defining a novel microenvironment within the MTJ adjacent to slow-twitch, but not fast-twitch, muscle. Interestingly, however, Fak, laminin, Fn and beta-dystroglycan concentrate at the MTJ in mutants that do not have slow-twitch fibers. Taken together, these data elucidate novel and dynamic microenvironments within the MTJ and indicate that MTJ morphogenesis is spatially and temporally complex.
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Affiliation(s)
- Chelsi J Snow
- School of Biology and Ecology, University of Maine, Orono, ME 04469-2988, USA
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119
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Wilkinson GA, Schittny JC, Reinhardt DP, Klein R. Role for ephrinB2 in postnatal lung alveolar development and elastic matrix integrity. Dev Dyn 2008; 237:2220-34. [PMID: 18651661 DOI: 10.1002/dvdy.21643] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alveoli are formed in the lung by the insertion of secondary tissue folds, termed septa, which are subsequently remodeled to form the mature alveolar wall. Secondary septation requires interplay between three cell types: endothelial cells forming capillaries, contractile interstitial myofibroblasts, and epithelial cells. Here, we report that postnatal lung alveolization critically requires ephrinB2, a ligand for Eph receptor tyrosine kinases expressed by the microvasculature. Mice homozygous for the hypomorphic knockin allele ephrinB2DeltaV/DeltaV, encoding mutant ephrinB2 with a disrupted C-terminal PDZ interaction motif, show severe postnatal lung defects including an almost complete absence of lung alveoli and abnormal and disorganized elastic matrix. Lung alveolar formation is not sensitive to loss of ephrinB2 cytoplasmic tyrosine phosphorylation sites. Postnatal day 1 mutant lungs show extracellular matrix alterations without differences in proportions of major distal cell populations. We conclude that lung alveolar formation relies on endothelial ephrinB2 function.
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Affiliation(s)
- George A Wilkinson
- Department of Molecular Neurobiology, Max-Planck Institute of Neurobiology, Munich-Martinsried, Germany.
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120
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Snow CJ, Goody M, Kelly MW, Oster EC, Jones R, Khalil A, Henry CA. Time-lapse analysis and mathematical characterization elucidate novel mechanisms underlying muscle morphogenesis. PLoS Genet 2008; 4:e1000219. [PMID: 18833302 PMCID: PMC2543113 DOI: 10.1371/journal.pgen.1000219] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 09/09/2008] [Indexed: 12/26/2022] Open
Abstract
Skeletal muscle morphogenesis transforms short muscle precursor cells into long, multinucleate myotubes that anchor to tendons via the myotendinous junction (MTJ). In vertebrates, a great deal is known about muscle specification as well as how somitic cells, as a cohort, generate the early myotome. However, the cellular mechanisms that generate long muscle fibers from short cells and the molecular factors that limit elongation are unknown. We show that zebrafish fast muscle fiber morphogenesis consists of three discrete phases: short precursor cells, intercalation/elongation, and boundary capture/myotube formation. In the first phase, cells exhibit randomly directed protrusive activity. The second phase, intercalation/elongation, proceeds via a two-step process: protrusion extension and filling. This repetition of protrusion extension and filling continues until both the anterior and posterior ends of the muscle fiber reach the MTJ. Finally, both ends of the muscle fiber anchor to the MTJ (boundary capture) and undergo further morphogenetic changes as they adopt the stereotypical, cylindrical shape of myotubes. We find that the basement membrane protein laminin is required for efficient elongation, proper fiber orientation, and boundary capture. These early muscle defects in the absence of either lamininβ1 or lamininγ1 contrast with later dystrophic phenotypes in lamininα2 mutant embryos, indicating discrete roles for different laminin chains during early muscle development. Surprisingly, genetic mosaic analysis suggests that boundary capture is a cell-autonomous phenomenon. Taken together, our results define three phases of muscle fiber morphogenesis and show that the critical second phase of elongation proceeds by a repetitive process of protrusion extension and protrusion filling. Furthermore, we show that laminin is a novel and critical molecular cue mediating fiber orientation and limiting muscle cell length. Despite the importance of muscle fiber development and tendon attachment, this process is incompletely understood in vertebrates. One critical step is muscle fiber elongation; muscle precursor cells are short and subsequent elongation/fusion generates long, multinucleate muscle fibers. Using a vertebrate model organism, the zebrafish, we find that single round myoblasts elongate to span the entire width of the myotome prior to fusion. Using rigorous and objective mathematical characterization techniques, we can further divide muscle development into three stages: short precursor cells, intercalation/elongation, and boundary capture/myotube formation. The second phase, elongation, occurs via a two-step mechanism of protrusion extension and filling. Myotube formation involves boundary capture, where the ends of muscle fibers anchor themselves to the myotome boundary and stop elongating. We show that the protein laminin is required for boundary capture, normal fiber length, and proper fiber orientation. Genetic mosaic experiments in laminin-deficient embryos reveal that boundary capture is a cell autonomous phenomenon. Wild-type (normal) cells capture the boundary appropriately and stop elongating in laminin-deficient embryos. Although adhesion to laminin has been implicated in muscular dystrophies where the attachment between muscle cells and tendons fails, no early developmental requirements for laminin in fast muscle morphogenesis have been shown until now.
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Affiliation(s)
- Chelsi J. Snow
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
| | - Michelle Goody
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
| | - Meghan W. Kelly
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
| | - Emma C. Oster
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
| | - Robert Jones
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
| | - Andre Khalil
- Department of Mathematics and Statistics, University of Maine, Orono, Maine, United States of America
- Institute for Molecular Biophysics, The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Clarissa A. Henry
- School of Biology and Ecology, University of Maine, Orono, Maine, United States of America
- Institute for Molecular Biophysics, The Jackson Laboratory, Bar Harbor, Maine, United States of America
- * E-mail:
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Snow CJ, Peterson MT, Khalil A, Henry CA. Muscle development is disrupted in zebrafish embryos deficient for fibronectin. Dev Dyn 2008; 237:2542-53. [PMID: 18729220 PMCID: PMC2572006 DOI: 10.1002/dvdy.21670] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
After somitogenesis, skeletal muscle precursors elongate into muscle fibers that anchor to the somite boundary, which becomes the myotome boundary. Fibronectin (Fn) is a major component of the extracellular matrix in both boundaries. Although Fn is required for somitogenesis, effects of Fn disruption on subsequent muscle development are unknown. We show that fn knockdown disrupts myogenesis. Muscle morphogenesis is more disrupted in fn morphants than in a mutant where initial somite boundaries did not form, aei/deltaD. We quantified this disruption using the two-dimensional Wavelet-Transform Modulus Maxima method, which uses the variation of intensity in an image with respect to the direction considered to characterize the structure in a cell lattice. We show that fibers in fn morphants are less organized than in aei/deltaD mutant embryos. Fast- and slow-twitch muscle lengths are also more frequently uncoupled. These data suggest that fn may function to regulate fiber organization and limit fast-twitch muscle fiber length.
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Affiliation(s)
- Chelsi J Snow
- School of Biology and Ecology, University of Maine, Orono, Maine 04469-5735, USA
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122
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Özbudak EM, Lewis J. Notch signalling synchronizes the zebrafish segmentation clock but is not needed to create somite boundaries. PLoS Genet 2008; 4:e15. [PMID: 18248098 PMCID: PMC2222926 DOI: 10.1371/journal.pgen.0040015] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Accepted: 12/11/2007] [Indexed: 01/03/2023] Open
Abstract
Somite segmentation depends on a gene expression oscillator or clock in the posterior presomitic mesoderm (PSM) and on read-out machinery in the anterior PSM to convert the pattern of clock phases into a somite pattern. Notch pathway mutations disrupt somitogenesis, and previous studies have suggested that Notch signalling is required both for the oscillations and for the read-out mechanism. By blocking or overactivating the Notch pathway abruptly at different times, we show that Notch signalling has no essential function in the anterior PSM and is required only in the posterior PSM, where it keeps the oscillations of neighbouring cells synchronized. Using a GFP reporter for the oscillator gene her1, we measure the influence of Notch signalling on her1 expression and show by mathematical modelling that this is sufficient for synchronization. Our model, in which intracellular oscillations are generated by delayed autoinhibition of her1 and her7 and synchronized by Notch signalling, explains the observations fully, showing that there are no grounds to invoke any additional role for the Notch pathway in the patterning of somite boundaries in zebrafish. The somites—the embryonic segments of the vertebrate body—form one after another from tissue at the tail end of the embryo. A gene expression oscillator, the somite segmentation clock, operating in this tail region, marks out a periodic spatial pattern and so controls the segmentation process. Evidence from mutants shows that the Notch cell-cell signalling pathway has a critical role in the clock mechanism. However, when we switch on a blockade of Notch signalling, by immersing zebrafish embryos in the chemical inhibitor DAPT, the next ∼12 somites form normally, and only after that do disrupted somites appear. We show that this is because Notch signalling is needed only to maintain synchrony between the clocks of individual cells. The cells take about seven cycles to drift out of synchrony when Notch-mediated communication is blocked, and then a further five cycles to pass from the site where the tissue receives its “time-stamp” to the site where overt segmentation begins. By mathematical modelling, backed up with measurements on transgenic embryos, we show how Notch signalling may act at a molecular level to synchronise the intracellular oscillators of adjacent individual cells.
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Affiliation(s)
- Ertuğrul M Özbudak
- Vertebrate Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom
| | - Julian Lewis
- Vertebrate Development Laboratory, Cancer Research UK London Research Institute, London, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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123
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Zhang L, Kendrick C, Jülich D, Holley SA. Cell cycle progression is required for zebrafish somite morphogenesis but not segmentation clock function. Development 2008; 135:2065-70. [PMID: 18480162 PMCID: PMC2923836 DOI: 10.1242/dev.022673] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cell division, differentiation and morphogenesis are coordinated during embryonic development, and frequently are in disarray in pathologies such as cancer. Here, we present a zebrafish mutant that ceases mitosis at the beginning of gastrulation, but that undergoes axis elongation and develops blood, muscle and a beating heart. We identify the mutation as being in early mitotic inhibitor 1 (emi1), a negative regulator of the Anaphase Promoting Complex, and use the mutant to examine the role of the cell cycle in somitogenesis. The mutant phenotype indicates that axis elongation during the segmentation period is driven substantially by cell migration. We find that the segmentation clock, which regulates somitogenesis, functions normally in the absence of cell cycle progression, and observe that mitosis is a modest source of noise for the clock. Somite morphogenesis involves the epithelialization of the somite border cells around a core of mesenchyme. As in wild-type embryos, somite boundary cells are polarized along a Fibronectin matrix in emi1(-/-). The mutants also display evidence of segment polarity. However, in the absence of a normal cell cycle, somites appear to hyper-epithelialize, as the internal mesenchymal cells exit the core of the somite after initial boundary formation. Thus, cell cycle progression is not required during the segmentation period for segmentation clock function but is necessary for the normal segmental arrangement of epithelial borders and internal mesenchymal cells.
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Affiliation(s)
- Lixia Zhang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
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124
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Kotani T, Kawakami K. Misty somites, a maternal effect gene identified by transposon-mediated insertional mutagenesis in zebrafish that is essential for the somite boundary maintenance. Dev Biol 2008; 316:383-96. [PMID: 18342848 PMCID: PMC2443191 DOI: 10.1016/j.ydbio.2008.01.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/03/2008] [Accepted: 01/29/2008] [Indexed: 01/25/2023]
Abstract
Somite boundary formation is crucial for segmentation of vertebrate somites and vertebrae and skeletal muscle morphogenesis. Previously, we developed a Tol2 transposon-mediated gene trap method in zebrafish. In the present study, we aimed to isolate transposon insertions that trap maternally-expressed genes. We found that homozygous female fish carrying a transposon insertion within a maternally-expressed gene misty somites (mys) produced embryos that showed obscure somite boundaries at the early segmentation stage (12-13 hpf). The somite boundaries became clear and distinct after this period and the embryos survived to adulthood. This phenotype was rescued by expression of mys cDNA in the homozygous adults, confirming that it was caused by a decreased mys activity. We analyzed a role of the mys gene by using morpholino oligonucleotides (MOs). The MO-injected embryo exhibited severer phenotypes than the insertional mutant probably because the mys gene was partially active in the insertional mutant. The MO-injected embryo also showed the obscure somite boundary phenotype. Fibronectin and phosphorylated FAK at the intersomitic regions were accumulated at the boundaries at this stage, but, unlike wild type embryos, somitic cells adjacent to the boundaries did not undergo epithelialization, suggesting that Mys is required for epithelialization of the somitic cells. Then in the MO-injected embryos, the boundaries once became clear and distinct, but, in the subsequent stages, disappeared, resulting in abnormal muscle morphogenesis. Accumulation of Fibronectin and phosphorylated FAK observed in the initial stage also disappeared. Thus, Mys is crucial for maintenance of the somite boundaries formed at the initial stage. To analyze the mys defect at the cellular level, we placed cells dissociated from the MO-injected embryo on Fibronectin-coated glasses. By this cell spreading assay, we found that the mys-deficient cells reduced the activity to form lamellipodia on Fibronectin while FAK was activated in these cells. Thus, we demonstrate that a novel gene misty somites is essential for epithelialization of the somitic cells and maintenance of the somite boundary. Furthermore, Mys may play a role in a cellular pathway leading to lamellipodia formation in response to the Fibronectin signaling. We propose that the Tol2 transposon mediated gene trap method is powerful to identify a novel gene involved in vertebrate development.
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Affiliation(s)
- Tomoya Kotani
- Division of Molecular and Developmental Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
- Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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125
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Abstract
Bidirectional signaling has emerged as an important signature by which Ephs and ephrins control biological functions. Eph/ephrin signaling participates in a wide spectrum of developmental processes, and cross-regulation with other communication pathways lies at the heart of the complexity underlying their function in vivo. Here, we review in vitro and in vivo data describing molecular, functional, and genetic interactions between Eph/ephrin and other cell surface signaling pathways. The complexity of Eph/ephrin function is discussed in terms of the pathways that regulate Eph/ephrin signaling and also the pathways that are regulated by Eph/ephrin signaling.
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Affiliation(s)
- Dina Arvanitis
- Université de Toulouse, Centre de Biologie du Développement, 31062 Toulouse cedex 9, France
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126
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Recent papers on zebrafish and other aquarium fish models. Zebrafish 2008; 2:125-37. [PMID: 18248172 DOI: 10.1089/zeb.2005.2.125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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127
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Genetic analysis of somite formation in laboratory fish models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008. [PMID: 21038770 DOI: 10.1007/978-0-387-09606-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
The repeated appearance of somites is one of the most fascinating aspects of vertebrate embryogenesis. Recent studies identified complex regulatory circuits that provide the molecular basis for the "clock and wave front" model, postulated almost 30 years ago by Cooke and Zeeman. The highly coordinated process of somite formation involves several networks of molecular cascades including the Delta/Notch, Wnt, FGF and retinoid signalling pathways. Studies in mouse, Xenopus and especially chicken over the last decade have helped to understand the role and interactions of these pathways in somitogenesis. More recently, this has been supplemented by experiments in zebrafish. This animal model offers the possibility of performing large scale mutagenesis screens to identify novel factors and pathways involved in somitogenesis. Molecular cloning of zebrafish somite mutants mainly resulted in genes that belong to the Delta/Notch pathway and therefore underlined the importance of this pathway during somitogenesis. The fact that other pathways have not yet been identified by genetic screening in this species was assumed to be caused by functional redundancy of duplicated genes in zebrafish. In 2000, a large-scale mutagenesis screen has been initiated in Kyoto, Japan using the related teleost medaka (Oryzias latipes). In this screen, mutants with unique phenotypes have been identified, which have not been described in zebrafish or mouse. In this chapter, we will review the progress that has been made in understanding the molecular control of somite formation in zebrafish and will discuss recent efforts to screen for novel phenotypes using medaka somitogenesis mutants.
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128
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Bouaouina M, Lad Y, Calderwood DA. The N-terminal domains of talin cooperate with the phosphotyrosine binding-like domain to activate beta1 and beta3 integrins. J Biol Chem 2007; 283:6118-25. [PMID: 18165225 DOI: 10.1074/jbc.m709527200] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activation of integrin adhesion receptors from low to high affinity in response to intracellular cues controls cell adhesion and signaling. Binding of the cytoskeletal protein talin to the beta3 integrin cytoplasmic tail is required for beta3 activation, and the integrin-binding PTB-like F3 domain of talin is sufficient to activate beta3 integrins. Here we report that, whereas the conserved talin-integrin interaction is also required for beta1 activation, and talin F3 binds beta1 and beta3 integrins with comparable affinity, expression of the talin F3 domain is not sufficient to activate beta1 integrins. beta1 integrin activation could, however, be detected following expression of larger talin fragments that included the N-terminal and F1 domains, and mutagenesis indicates that these domains cooperate with talin F3 to mediate beta1 activation. This effect is not due to increased affinity for the integrin beta tail and we hypothesize that the N-terminal domains function by targeting or orienting talin in such a way as to optimize the interaction with the integrin tail. Analysis of beta3 integrin activation indicates that inclusion of the N-terminal and F1 domains also enhances F3-mediated beta3 activation. Our results therefore reveal a role for the N-terminal and F1 domains of talin during integrin activation and highlight differences in talin-mediated activation of beta1 and beta3 integrins.
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Affiliation(s)
- Mohamed Bouaouina
- Department of Pharmacology and Interdepartmental Program in Vascular Biology and Transplantation, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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129
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Kragtorp KA, Miller JR. Integrin alpha5 is required for somite rotation and boundary formation in Xenopus. Dev Dyn 2007; 236:2713-20. [PMID: 17685483 DOI: 10.1002/dvdy.21280] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The morphogenesis of somites in Xenopus laevis is characterized by a complex process of cell turning that requires coordinated regulation of cell shape, adhesion, and motility. The integrin alpha5 subunit has been implicated in the formation of somite boundaries in organisms utilizing epithelialization to create morphologically distinct somites, but its function has not been examined in Xenopus. We used a splice-blocking morpholino to knock down expression of integrin alpha5 during somite formation. Loss of integrin alpha5 delayed somite turning and accumulation of integrin beta1 at somite boundaries, and disrupted the fibronectin matrix surrounding developing somites. Irregular somite boundaries with a sparse and discontinuous fibronectin matrix formed upon eventual completion of somite turning. Recovery of somite morphology was improved, but still incomplete in far posterior somites. These data demonstrate that the role of integrin alpha5 in somite boundary formation is conserved in a species using a unique mechanism of somitogenesis.
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Affiliation(s)
- Katherine A Kragtorp
- Department of Genetics, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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130
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Kappen C, Neubüser A, Balling R, Finnell R. Molecular basis for skeletal variation: insights from developmental genetic studies in mice. BIRTH DEFECTS RESEARCH. PART B, DEVELOPMENTAL AND REPRODUCTIVE TOXICOLOGY 2007; 80:425-50. [PMID: 18157899 PMCID: PMC3938168 DOI: 10.1002/bdrb.20136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Skeletal variations are common in humans, and potentially are caused by genetic as well as environmental factors. We here review molecular principles in skeletal development to develop a knowledge base of possible alterations that could explain variations in skeletal element number, shape or size. Environmental agents that induce variations, such as teratogens, likely interact with the molecular pathways that regulate skeletal development.
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Affiliation(s)
- C Kappen
- Center for Human Molecular Genetics, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA.
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131
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Akanuma T, Koshida S, Kawamura A, Kishimoto Y, Takada S. Paf1 complex homologues are required for Notch-regulated transcription during somite segmentation. EMBO Rep 2007; 8:858-63. [PMID: 17721442 PMCID: PMC1973952 DOI: 10.1038/sj.embor.7401045] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 06/28/2007] [Accepted: 06/29/2007] [Indexed: 01/13/2023] Open
Abstract
Members of the yeast polymerase-associated factor 1 (Paf1) complex, which is composed of at least five components (Paf1, Rtf1, Cdc73, Leo1 and Ctr9), are conserved from yeast to humans. Although these proteins have been implicated in RNA polymerase II-mediated transcription, their roles in vertebrate development have not been explained. Here, we show that a zebrafish mutant with a somite segmentation defect is deficient in rtf1. In addition, embryos deficient in rtf1 or ctr9 show abnormal development of the heart, ears and neural crest cells. rtf1 is required for correct RNA levels of the Notch-regulated genes her1, her7 and deltaC, and also for Notch-induced her1 expression in the presomitic mesoderm. Furthermore, the phenotype observed in rtf1-deficient mutants is enhanced by an additional deficiency in mind bomb, which encodes an effector of Notch signalling. Therefore, zebrafish homologues of the yeast Paf1 complex seem to preferentially affect a subset of genes, including Notch-regulated genes, during embryogenesis.
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Affiliation(s)
- Takashi Akanuma
- Okazaki Institute for Integrative Biosciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Sumito Koshida
- Okazaki Institute for Integrative Biosciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Basic Biology, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8787, Japan
| | - Akinori Kawamura
- Okazaki Institute for Integrative Biosciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | | | - Shinji Takada
- Okazaki Institute for Integrative Biosciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Basic Biology, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8787, Japan
- Tel: +81 564 59 5241; Fax: +81 564 59 5240; E-mail:
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Rifes P, Carvalho L, Lopes C, Andrade RP, Rodrigues G, Palmeirim I, Thorsteinsdóttir S. Redefining the role of ectoderm in somitogenesis: a player in the formation of the fibronectin matrix of presomitic mesoderm. Development 2007; 134:3155-65. [PMID: 17670788 DOI: 10.1242/dev.003665] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The absence of ectoderm impairs somite formation in cultured presomitic mesoderm (PSM) explants, suggesting that an ectoderm-derived signal is essential for somitogenesis. Here we show in chick that the standard enzymatic treatments used for explant isolation destroy the fibronectin matrix surrounding the anterior PSM, which fails to form somites when cultured for 6 hours. By contrast, explants isolated with collagenase retain their fibronectin matrix and form somites under identical culture conditions. The additional presence of ectoderm enhances somite formation, whereas endoderm has no effect. Furthermore, we show that pancreatin-isolated PSM explants cultured in fibronectin-supplemented medium, form significantly more somites than control explants. Interestingly, ectoderm is the major producer of fibronectin (Fn1) transcripts, whereas all but the anterior-most region of the PSM expresses the fibronectin assembly receptor, integrin alpha5 (Itga5). We thus propose that the ectoderm-derived fibronectin is assembled by mesodermal alpha5beta1 integrin on the surface of the PSM. Finally, we demonstrate that inhibition of fibronectin fibrillogenesis in explants with ectoderm abrogates somitogenesis. We conclude that a fibronectin matrix is essential for morphological somite formation and that a major, previously unrecognised role of ectoderm in somitogenesis is the synthesis of fibronectin.
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Affiliation(s)
- Pedro Rifes
- Departamento de Biologia Animal e Centro de Biologia Ambiental, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
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133
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Ablooglu AJ, Kang J, Handin RI, Traver D, Shattil SJ. The zebrafish vitronectin receptor: Characterization of integrinαVandβ3expression patterns in early vertebrate development. Dev Dyn 2007; 236:2268-76. [PMID: 17626277 DOI: 10.1002/dvdy.21229] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
alphaVbeta3 is a receptor for vitronectin and other extracellular matrix ligands, and it has been implicated in angiogenesis and osteoclast function in mammals. We have cloned full-length cDNAs of zebrafish integrin alphaV (itgalphaV), and two paralogous zebrafish beta3 integrins (itgbeta3.1 and itgbeta3.2). Whole-mount in situ hybridization analysis revealed that alphaV and beta3.1 share overlapping expression domains in apical ectodermal ridge, ventricular myocardium, hypothalamus, posterior tuberculum, medial tectal proliferation zone, and in the odontogenic field of the bilateral pharyngeal dentitions. In contrast to beta3.1, beta3.2 is transiently expressed throughout the developing embryo. In situ hybridization profiles and heterologous expression of proteins in tissue culture cells suggest that beta3.1 is the major beta3 paralog that associates with alphaV in zebrafish. Furthermore, when beta3.1 expression profiles are compared to those of other potential alphaV partners (beta1, beta5, and beta8), pharyngeal dentitions appear to represent a unique expression field for alphaV and beta3.1.
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Affiliation(s)
- Ararat J Ablooglu
- Division of Hematology-Oncology, Department of Medicine, University of California San Diego, La Jolla, California 92093-0726, USA.
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134
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Takahashi S, Leiss M, Moser M, Ohashi T, Kitao T, Heckmann D, Pfeifer A, Kessler H, Takagi J, Erickson HP, Fässler R. The RGD motif in fibronectin is essential for development but dispensable for fibril assembly. ACTA ACUST UNITED AC 2007; 178:167-78. [PMID: 17591922 PMCID: PMC2064432 DOI: 10.1083/jcb.200703021] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Fibronectin (FN) is secreted as a disulfide-bonded FN dimer. Each subunit contains three types of repeating modules: FN-I, FN-II, and FN-III. The interactions of α5β1 or αv integrins with the RGD motif of FN-III repeat 10 (FN-III10) are considered an essential step in the assembly of FN fibrils. To test this hypothesis in vivo, we replaced the RGD motif with the inactive RGE in mice. FN-RGE homozygous embryos die at embryonic day 10 with shortened posterior trunk, absent tail bud–derived somites, and severe vascular defects resembling the phenotype of α5 integrin–deficient mice. Surprisingly, the absence of a functional RGD motif in FN did not compromise assembly of an FN matrix in mutant embryos or on mutant cells. Matrix assembly assays and solid-phase binding assays reveal that αvβ3 integrin assembles FN-RGE by binding an isoDGR motif in FN-I5, which is generated by the nonenzymatic rearrangement of asparagines (N) into an iso-aspartate (iso-D). Our findings demonstrate that FN contains a novel motif for integrin binding and fibril formation whose activity is controlled by amino acid modification.
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Affiliation(s)
- Seiichiro Takahashi
- Max Planck Institute of Biochemistry, Department of Molecular Medicine, 82152 Martinsried, Germany
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135
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Kulesa PM, Schnell S, Rudloff S, Baker RE, Maini PK. From segment to somite: segmentation to epithelialization analyzed within quantitative frameworks. Dev Dyn 2007; 236:1392-402. [PMID: 17497694 PMCID: PMC2030567 DOI: 10.1002/dvdy.21199] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
One of the most visually striking patterns in the early developing embryo is somite segmentation. Somites form as repeated, periodic structures in pairs along nearly the entire caudal vertebrate axis. The morphological process involves short- and long-range signals that drive cell rearrangements and cell shaping to create discrete, epithelialized segments. Key to developing novel strategies to prevent somite birth defects that involve axial bone and skeletal muscle development is understanding how the molecular choreography is coordinated across multiple spatial scales and in a repeating temporal manner. Mathematical models have emerged as useful tools to integrate spatiotemporal data and simulate model mechanisms to provide unique insights into somite pattern formation. In this short review, we present two quantitative frameworks that address the morphogenesis from segment to somite and discuss recent data of segmentation and epithelialization.
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Affiliation(s)
- Paul M Kulesa
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
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136
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Abstract
Somites are the most obvious metameric structures in the vertebrate embryo. They are mesodermal segments that form in bilateral pairs flanking the notochord and are created sequentially in an anterior to posterior sequence concomitant with the posterior growth of the trunk and tail. Zebrafish somitogenesis is regulated by a clock that causes cells in the presomitic mesoderm (PSM) to undergo cyclical activation and repression of several notch pathway genes. Coordinated oscillation among neighboring cells manifests as stripes of gene expression that pass through the cells of the PSM in a posterior to anterior direction. As axial growth continually adds new cells to the posterior tail bud, cells of the PSM become relatively less posterior. This gradual assumption of a more anterior position occurs over developmental time and constitutes part of a maturation process that governs morphological segmentation in conjunction with the clock. Segment morphogenesis involves a mesenchymal to epithelial transition as prospective border cells at the anterior end of the mesenchymal PSM adopt a polarized, columnar morphology and surround a mesenchymal core of cells. The segmental pattern influences the development of the somite derivatives such as the myotome, and the myotome reciprocates to affect the formation of segment boundaries. While somites appear to be serially homologous, there may be variation in the segmentation mechanism along the body axis. Moreover, whereas the genetic architecture of the zebrafish, mouse, and chick segmentation clocks shares many common elements, there is evidence that the gene networks have undergone independent modification during evolution.
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Affiliation(s)
- Scott A Holley
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA.
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137
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Mara A, Schroeder J, Chalouni C, Holley SA. Priming, initiation and synchronization of the segmentation clock by deltaD and deltaC. Nat Cell Biol 2007; 9:523-30. [PMID: 17417625 DOI: 10.1038/ncb1578] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 03/22/2007] [Indexed: 02/06/2023]
Abstract
Zebrafish somitogenesis is governed by a segmentation clock that generates oscillations in expression of several Notch pathway genes, including her1, her7 and deltaC. Using a combination of pharmacological inhibition and Mendelian genetics, we show that DeltaD and DeltaC, two Notch ligands, represent functionally distinct signals within the segmentation clock. Using high-resolution fluorescent in situ hybridization, the oscillations were divided into phases based on eight distinct subcellular patterns of mRNA localization for 140,000 cells. her1, her7 and deltaC expression was examined in wild-type, deltaD(-/-) and deltaC(-/-) embryos. We identified areas within the tailbud where the clock is set up in the progenitor cells (priming), where the clock starts running (initiation), and where the clocks of neighbouring cells are entrained (synchronization). We find that the clocks of motile cells are primed by deltaD in a progenitor zone in the posterior tailbud and that deltaD is required for cells to initiate oscillations on exiting this zone. Oscillations of adjacent cells are synchronized and amplified by deltaC in the posterior presomitic mesoderm as cell movement subsides and cells maintain stable neighbour relationships.
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Affiliation(s)
- Andrew Mara
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA
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138
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Abstract
The generation and targeting of appropriate numbers and types of neurons to where they are needed in the brain is essential for the establishment, maintenance and modification of neural circuitry. This review aims to summarize the patterns, mechanisms and functional significance of neuronal migration in the postnatal brain, with an emphasis on the migratory events that persist in the mature brain.
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Affiliation(s)
- H Troy Ghashghaei
- UNC Neuroscience Center and the Department of Cell and Molecular Physiology, Room 7109B, 103 Mason Farm Road, The University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7250, USA
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139
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Sakaguchi T, Kikuchi Y, Kuroiwa A, Takeda H, Stainier DYR. The yolk syncytial layer regulates myocardial migration by influencing extracellular matrix assembly in zebrafish. Development 2007; 133:4063-72. [PMID: 17008449 DOI: 10.1242/dev.02581] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The roles of extra-embryonic tissues in early vertebrate body patterning have been extensively studied, yet we know little about their function during later developmental events. Here, we analyze the function of the zebrafish extra-embryonic yolk syncytial layer (YSL) specific transcription factor, Mtx1, and find that it plays an essential role in myocardial migration. Downregulating the function of Mtx1 in the YSL leads to cardia bifida, a phenotype in which the myocardial cells fail to migrate to the midline. Mtx1 in the extra-embryonic YSL appears to regulate the embryonic expression of fibronectin, a gene previously implicated in myocardial migration. We further show dosage-sensitive genetic interactions between mtx1 and fibronectin. Based on these data, we propose that the extra-embryonic YSL regulates myocardial migration, at least in part by influencing fibronectin expression and subsequent assembly of the extracellular matrix in embryonic tissues.
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Affiliation(s)
- Takuya Sakaguchi
- Department of Biochemistry and Biophysics and Programs in Developmental Biology, Genetics and Human Genetics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143-2711, USA
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140
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Deniziak M, Thisse C, Rederstorff M, Hindelang C, Thisse B, Lescure A. Loss of selenoprotein N function causes disruption of muscle architecture in the zebrafish embryo. Exp Cell Res 2007; 313:156-67. [PMID: 17123513 DOI: 10.1016/j.yexcr.2006.10.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 09/29/2006] [Accepted: 10/02/2006] [Indexed: 10/23/2022]
Abstract
Mutations in the gene coding for selenoprotein N (SelN), a selenium containing protein of unknown function, cause different forms of congenital muscular dystrophy in humans. These muscular diseases are characterized by early onset of hypotonia which predominantly affect in axial muscles. We used zebrafish as a model system to understand the function of SelN in muscle formation during embryogenesis. Zebrafish SelN is highly homologous to its human counterpart and amino acids corresponding to the mutated positions in human muscle diseases are conserved in the zebrafish protein. The sepn1 gene is highly expressed in the somites and notochord during early development. Inhibition of the sepn1 gene by injection of antisense morpholinos does not alter the fate of the muscular tissue, but causes muscle architecture disorganization and greatly reduced motility. Ultrastructural analysis of the myotomes reveals defects in muscle sarcomeric organization and in myofibers attachment, as well as altered myoseptum integrity. These studies demonstrate the important role of SelN for muscle organization during early development. Moreover, alteration of myofibrils architecture and tendon-like structure in embryo deficient for SelN function provide new insights into the pathological mechanism of SelN-related myopathy.
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Affiliation(s)
- Marzanna Deniziak
- Institut de Biologie Moléculaire et Cellulaire, UPR ARN du CNRS/Université Louis Pasteur, 15 rue René Descartes, 67084 Strasbourg, France
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141
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Yin C, Solnica-Krezel L. Convergence and extension movements affect dynamic notochord-somite interactions essential for zebrafish slow muscle morphogenesis. Dev Dyn 2007; 236:2742-56. [PMID: 17849437 DOI: 10.1002/dvdy.21295] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During vertebrate gastrulation, convergence and extension (C&E) movements shape and position the somites that form the fast and slow muscles. In zebrafish knypek;trilobite non-canonical Wnt mutants, defective C&E movements cause misshapen somites and reduction of slow muscle precursors, the adaxial cells. Here, we demonstrate essential roles of C&E in slow muscle morphogenesis. During segmentation, the adaxial cells change shapes and migrate laterally to form slow muscles at the myotome surface. Using confocal imaging techniques, we show that the adaxial cells undergo three-step shape changes, including dorsoventral elongation, anterior-ward rotation, and anteroposterior elongation. The adaxial cells in knypek;trilobite double mutants maintain prolonged contact with the notochord and fail to rotate anteriorly. Such a defect was suppressed by physical removal of their notochord or by introducing wild-type notochord cells into the mutant. We propose that in the double mutants, impaired C&E movements disrupt notochord development, which impedes the adaxial cell shape changes.
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Affiliation(s)
- Chunyue Yin
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, USA
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142
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Davy A, Soriano P. Ephrin-B2 forward signaling regulates somite patterning and neural crest cell development. Dev Biol 2006; 304:182-93. [PMID: 17223098 PMCID: PMC1892242 DOI: 10.1016/j.ydbio.2006.12.028] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 12/08/2006] [Accepted: 12/12/2006] [Indexed: 11/30/2022]
Abstract
Genetic studies in the mouse have implicated ephrin-B2 (encoded by the gene Efnb2) in blood vessel formation, cardiac development and remodeling of the lymphatic vasculature. Here we report that loss of ephrin-B2 leads to defects in populations of cranial and trunk neural crest cells (NCC) and to defective somite development. In addition, we show that Efnb1/Efnb2 double heterozygous embryos exhibit phenotypes in a number of NCC derivatives. Expression of one copy of a mutant version of Efnb2 that lacks tyrosine phosphorylation sites was sufficient to rescue the embryonic phenotypes associated with loss of Efnb2. Our results uncover an important role for ephrin-B2 in NCC and somites during embryogenesis and suggest that ephrin-B2 exerts many of its embryonic function via activation of forward signaling.
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143
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Morimoto M, Kiso M, Sasaki N, Saga Y. Cooperative Mesp activity is required for normal somitogenesis along the anterior–posterior axis. Dev Biol 2006; 300:687-98. [PMID: 16996494 DOI: 10.1016/j.ydbio.2006.08.043] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 07/10/2006] [Accepted: 08/19/2006] [Indexed: 11/16/2022]
Abstract
Mesp2 is a bHLH-type transcription factor that plays a key role during somitogenesis. Mesp2 is transiently expressed and is quickly degraded once translated. In our current study, we find that Mesp2 contains a degradation domain, which acts as a target of proteasome-mediated proteolysis and appears to play this role in vivo. We have also defined the nuclear localization signals (NLS) and constructed a minimum Mesp2 protein (P2-HD) composed of the NLS, bHLH and the degradation domains. The ability of the P2-HD as a transcription factor in vivo was examined. Some of the defects that had been previously observed in the Mesp2-null mice were rescued in the knock-in mice but only in the posterior half of the body, indicating differential effects of P2-HD along the anterior-posterior (AP) axis. In addition, quantitative analysis of the expression along the AP axis revealed that the relative levels of Mesp2 increased, whereas Mesp1 is down-regulated in the later stages of development by the activities of Mesp2 in the wild-type embryo. Moreover, we have found that somitogenesis in the early stages is more susceptible to changes in the Mesp gene dosage, indicating that a threshold level of Mesp activity must be required for the progression of normal somitogenesis.
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Affiliation(s)
- Mitsuru Morimoto
- Division of Mammalian Development, National Institute of Genetics, Yata 1111, Mishima 411-8540, Japan
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144
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Larsen M, Artym VV, Green JA, Yamada KM. The matrix reorganized: extracellular matrix remodeling and integrin signaling. Curr Opin Cell Biol 2006; 18:463-71. [PMID: 16919434 DOI: 10.1016/j.ceb.2006.08.009] [Citation(s) in RCA: 370] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Accepted: 08/03/2006] [Indexed: 12/22/2022]
Abstract
Via integrins, cells can sense dimensionality and other physical and biochemical properties of the extracellular matrix (ECM). Cells respond differently to two-dimensional substrates and three-dimensional environments, activating distinct signaling pathways for each. Direct integrin signaling and indirect integrin modulation of growth factor and other intracellular signaling pathways regulate ECM remodeling and control subsequent cell behavior and tissue organization. ECM remodeling is critical for many developmental processes, and remodeled ECM contributes to tumorigenesis. These recent advances in the field provide new insights and raise new questions about the mechanisms of ECM synthesis and proteolytic degradation, as well as the roles of integrins and tension in ECM remodeling.
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Affiliation(s)
- Melinda Larsen
- Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive, MSC 4370, Bethesda, MD 20892-4370, USA
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145
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Wang Y, Qian L, Dong Y, Jiang Q, Gui Y, Zhong TP, Song H. Myocyte-specific enhancer factor 2A is essential for zebrafish posterior somite development. Mech Dev 2006; 123:783-91. [PMID: 16942865 DOI: 10.1016/j.mod.2006.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 07/03/2006] [Accepted: 07/11/2006] [Indexed: 11/25/2022]
Abstract
Somite development is governed tightly by genetic factors. In the large-scale mutagenesis screens of zebrafish, no mutations were linked to myocyte enhancer factor 2A (MEF2A) locus. In this study, we find that MEF2A knock-down embryos display a downward tail curvature and have U-shaped posterior somites. Furthermore, we demonstrate that MEF2A is required for Hedgehog signaling. MEF2A inhibition results in induction of apoptosis in the posterior somites. We further find that Hedgehog signaling can negatively regulate MEF2A expression in the somites. Microarray studies reveal a number of genes that are differentially expressed in the MEF2A morphants. Our studies suggest that MEF2A is essential for zebrafish posterior somite development.
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Affiliation(s)
- Yuexiang Wang
- Department of Molecular Genetics, Shanghai Medical School and Key Laboratory of Molecular Medicine, Ministry of Education, Fudan University, Shanghai 200032, PR China
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146
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van der Meer DLM, Marques IJ, Leito JTD, Besser J, Bakkers J, Schoonheere E, Bagowski CP. Zebrafish cypher is important for somite formation and heart development. Dev Biol 2006; 299:356-72. [PMID: 16982050 DOI: 10.1016/j.ydbio.2006.07.032] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 05/25/2006] [Accepted: 07/26/2006] [Indexed: 11/26/2022]
Abstract
Mammalian CYPHER (Oracle, KIA0613), a member of the PDZ-LIM family of proteins (Enigma/LMP-1, ENH, ZASP/Cypher, RIL, ALP, and CLP-36), has been associated with cardiac and muscular myopathies. Targeted deletion of Cypher in mice is neonatal lethal possibly caused by myopathies. To further investigate the role of cypher in development, we have cloned the zebrafish orthologue. We present here the gene, domain structure, and expression pattern of zebrafish cypher during development. Cypher was not present as a maternal mRNA and was absent during early development. Cypher mRNA was first detected at the 3-somite stage in adaxial somites, and as somites matured, cypher expression gradually enveloped the whole somite. Later, cypher expression was also found in the heart, in head and jaw musculature, and in the brain. We further identified 13 alternative spliced forms of cypher from zebrafish heart and skeletal muscle tissue, among them a very short form containing the PDZ domain but lacking the ZM (ZASP-like) motif and the LIM domains. Targeted gene knock-down experiments using cypher antisense morpholinos led to severe defects, including truncation of the embryo, deformation of somites, dilatation of the pericardium, and thinning of the ventricular wall. The phenotype could be rescued by a cypher form, which contains the PDZ domain and the ZM motif, but lacks all three LIM domains. These findings indicate that a PDZ domain protein is important for normal somite formation and in normal heart development. Treatment of zebrafish embryos with cyclopamine, which disrupts hedgehog signaling, abolished cypher expression in 9 somite and 15-somite stage embryos. Taken together, our data suggest that cypher may play a role downstream of sonic hedgehog, in a late stage of somite development, when slow muscle fibers differentiate and migrate from the adaxial cells.
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Affiliation(s)
- David L M van der Meer
- Institute of Biology, Department of Integrative Zoology University of Leiden, Kaiserstraat 3, 2311 GN, The Netherlands
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147
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Holley SA. Anterior-posterior differences in vertebrate segments: specification of trunk and tail somites in the zebrafish blastula. Genes Dev 2006; 20:1831-7. [PMID: 16847343 DOI: 10.1101/gad.1453706] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Scott A Holley
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
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148
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Sieger D, Ackermann B, Winkler C, Tautz D, Gajewski M. her1 and her13.2 are jointly required for somitic border specification along the entire axis of the fish embryo. Dev Biol 2006; 293:242-51. [PMID: 16545363 DOI: 10.1016/j.ydbio.2006.02.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 01/27/2006] [Accepted: 02/03/2006] [Indexed: 11/21/2022]
Abstract
Delta-Notch and FGF signaling are involved in the control of somitogenesis in zebrafish. her genes are generally known as downstream targets of Delta-Notch signaling, but the her13.2 gene from zebrafish has recently been shown to depend on FGF signaling only. We have here studied the functional role of her13.2 in conjunction with her genes that are under Delta-Notch control. We show that joint inactivation of her1 and her13.2 leads to a complete loss of all somitic borders, including the most anterior ones. This somitic phenotype is much stronger than would be expected from the effects of the inactivation of either gene alone. A joint inactivation of her13.2 and her7, which is a paralogue of her1, does not show this enhanced effect. Thus, our results confirm inferences from in vitro studies that her1 and her13.2 form specific heterodimers, which may directly be required for regulating further target genes. These two her genes thus constitute the link between Delta-Notch pathway and FGF signaling during entire somitogenesis. We show that this interaction is conserved in the rice fish medaka, as a joint inactivation of the respective orthologues leads also to the same phenotype as in zebrafish. In addition, our results suggest that the mechanisms for anterior and posterior somite formation are not principally different, although the anterior somites often seem more refractory to genetic perturbations.
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Affiliation(s)
- Dirk Sieger
- Universität zu Köln, Institut für Genetik, Zuelpicherstr. 47, 50674 Köln, Germany
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149
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Rodrigues S, Santos J, Palmeirim I. Molecular characterization of the rostral-most somites in early somitic stages of the chick embryo. Gene Expr Patterns 2006; 6:673-7. [PMID: 16488196 DOI: 10.1016/j.modgep.2006.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 12/28/2005] [Accepted: 01/07/2006] [Indexed: 10/25/2022]
Abstract
Segmentation consists on the progressive formation of repetitive embryonic structures, named somites, which are formed from the most rostral part of the presomitic mesoderm. Somites are subdivided into anterior and posterior compartments and several genes are differentially expressed in either compartment. This has provided evidence for the importance of establishing the anterior-posterior polarity within each somite, which is critical for the correct segmented pattern of the adult vertebrate body. Although all somites appear morphologically similar, fate map studies have shown that the first 4 somites do not give rise to segmented structures, in contrast to more posterior ones. Moreover, in several somitogenesis-related mutants the anterior somites are not affected while posterior somites present clear defects or do not form at all. Altogether these data suggest relevant differences between rostral and caudal somites. In order to check for molecular differences between anterior and posterior somites, we have performed a detailed expression pattern analysis of several Notch signalling related genes. For the first time, we show that the somitic expression pattern profile is not the same along the anterior-posterior axis and that the differences are not observed always at the same somite level.
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Affiliation(s)
- Sofia Rodrigues
- Instituto Gulbenkian de Ciência, Centro de Biologia do Desenvolvimento, Oeiras, Portugal
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150
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Kragtorp KA, Miller JR. Regulation of somitogenesis by Ena/VASP proteins and FAK during Xenopus development. Development 2006; 133:685-95. [PMID: 16421193 DOI: 10.1242/dev.02230] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The metameric organization of the vertebrate body plan is established during somitogenesis as somite pairs sequentially form along the anteroposterior axis. Coordinated regulation of cell shape, motility and adhesion are crucial for directing the morphological segmentation of somites. We show that members of the Ena/VASP family of actin regulatory proteins are required for somitogenesis in Xenopus. Xenopus Ena (Xena) localizes to the cell periphery in the presomitic mesoderm (PSM), and is enriched at intersomitic junctions and at myotendinous junctions in somites and the myotome, where it co-localizes with β1-integrin, vinculin and FAK. Inhibition of Ena/VASP function with dominant-negative mutants results in abnormal somite formation that correlates with later defects in intermyotomal junctions. Neutralization of Ena/VASP activity disrupts cell rearrangements during somite rotation and leads to defects in the fibronectin (FN) matrix surrounding somites. Furthermore, inhibition of Ena/VASP function impairs FN matrix assembly, spreading of somitic cells on FN and autophosphorylation of FAK, suggesting a role for Ena/VASP proteins in the modulation of integrin-mediated processes. We also show that inhibition of FAK results in defects in somite formation, blocks FN matrix deposition and alters Xena localization. Together, these results provide evidence that Ena/VASP proteins and FAK are required for somite formation in Xenopus and support the idea that Ena/VASP and FAK function in a common pathway to regulate integrin-dependent migration and adhesion during somitogenesis.
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Affiliation(s)
- Katherine A Kragtorp
- Department of Genetics, Cell Biology and Development and Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
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