151
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Speirs CK, Jernigan KK, Kim SH, Cha YI, Lin F, Sepich DS, DuBois RN, Lee E, Solnica-Krezel L. Prostaglandin Gbetagamma signaling stimulates gastrulation movements by limiting cell adhesion through Snai1a stabilization. Development 2010; 137:1327-37. [PMID: 20332150 DOI: 10.1242/dev.045971] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Gastrulation movements form the germ layers and shape them into the vertebrate body. Gastrulation entails a variety of cell behaviors, including directed cell migration and cell delamination, which are also involved in other physiological and pathological processes, such as cancer metastasis. Decreased Prostaglandin E(2) (PGE(2)) synthesis due to interference with the Cyclooxygenase (Cox) and Prostaglandin E synthase (Ptges) enzymes halts gastrulation and limits cancer cell invasiveness, but how PGE(2) regulates cell motility remains unclear. Here we show that PGE(2)-deficient zebrafish embryos, impaired in the epiboly, internalization, convergence and extension gastrulation movements, exhibit markedly increased cell-cell adhesion, which contributes to defective cell movements in the gastrula. Our analyses reveal that PGE(2) promotes cell protrusive activity and limits cell adhesion by modulating E-cadherin transcript and protein, in part through stabilization of the Snai1a (also known as Snail1) transcriptional repressor, an evolutionarily conserved regulator of cell delamination and directed migration. We delineate a pathway whereby PGE(2) potentiates interaction between the receptor-coupled G protein betagamma subunits and Gsk3beta to inhibit proteasomal degradation of Snai1a. However, overexpression of beta-catenin cannot stabilize Snai1a in PGE(2)-deficient gastrulae. Thus, the Gsk3beta-mediated and beta-catenin-independent inhibition of cell adhesion by Prostaglandins provides an additional mechanism for the functional interactions between the PGE(2) and Wnt signaling pathways during development and disease. We propose that ubiquitously expressed PGE(2) synthesizing enzymes, by promoting the stability of Snai1a, enable the precise and rapid regulation of cell adhesion that is required for the dynamic cell behaviors that drive various gastrulation movements.
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Affiliation(s)
- Christina K Speirs
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
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152
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Brodland GW, Chen X, Lee P, Marsden M. From genes to neural tube defects (NTDs): insights from multiscale computational modeling. HFSP JOURNAL 2010; 4:142-52. [PMID: 21119766 DOI: 10.2976/1.3338713] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 02/05/2010] [Indexed: 12/21/2022]
Abstract
The morphogenetic movements, and the embryonic phenotypes they ultimately produce, are the consequence of a series of events that involve signaling pathways, cytoskeletal components, and cell- and tissue-level mechanical interactions. In order to better understand how these events work together in the context of amphibian neurulation, an existing multiscale computational model was augmented. Geometric data for this finite element-based mechanical model were obtained from 3D surface reconstructions of live axolotl embryos and serial sections of fixed specimens. Tissue mechanical properties were modeled using cell-based constitutive equations that include internal force generation and cell rearrangement, and equation parameters were adjusted manually to reflect biochemical changes including alterations in Shroom or the planar-cell-polarity pathway. The model indicates that neural tube defects can arise when convergent extension of the neural plate is reduced by as little as 20%, when it is eliminated on one side of the embryo, when neural ridge elevation is disrupted, when tension in the non-neural ectoderm is increased, or when the ectoderm thickness is increased. Where comparable conditions could be induced in Xenopus embryos, good agreement was found, an important step in model validation. The model reveals the neurulating embryo to be a finely tuned biomechanical system.
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153
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Tay HG, Ng YW, Manser E. A vertebrate-specific Chp-PAK-PIX pathway maintains E-cadherin at adherens junctions during zebrafish epiboly. PLoS One 2010; 5:e10125. [PMID: 20405038 PMCID: PMC2853574 DOI: 10.1371/journal.pone.0010125] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 03/13/2010] [Indexed: 11/25/2022] Open
Abstract
Background In early vertebrate development, embryonic tissues modulate cell adhesiveness and acto-myosin contractility to correctly orchestrate the complex processes of gastrulation. E-cadherin (E-cadh) is the earliest expressed cadherin and is needed in the mesendodermal progenitors for efficient migration [1], [2]. Regulatory mechanisms involving directed E-cadh trafficking have been invoked downstream of Wnt11/5 signaling [3]. This non-canonical Wnt pathway regulates RhoA-ROK/DAAM1 to control the acto-myosin network. However, in this context nothing is known of the intracellular signals that participate in the correct localization of E-cadh, other than a need for Rab5c signaling [3]. Methodology/Principal Findings By studying loss of Chp induced by morpholino-oligonucleotide injection in zebrafish, we find that the vertebrate atypical Rho-GTPase Chp is essential for the proper disposition of cells in the early embryo. The underlying defect is not leading edge F-actin assembly (prominent in the cells of the envelope layer), but rather the failure to localize E-cadh and β-catenin at the adherens junctions. Loss of Chp results in delayed epiboly that can be rescued by mRNA co-injection, and phenocopies zebrafish E-cadh mutants [4], [5]. This new signaling pathway involves activation of an effector kinase PAK, and involvement of the adaptor PAK-interacting exchange factor PIX. Loss of signaling by any of the three components results in similar underlying defects, which is most prominent in the epithelial-like envelope layer. Conclusions/Significance Our current study uncovers a developmental pathway involving Chp/PAK/PIX signaling, which helps co-ordinate E-cadh disposition to promote proper cell adhesiveness, and coordinate movements of the three major cell layers in epiboly. Our data shows that without Chp signaling, E-cadh shifts to intracellular vesicles rather than the adhesive contacts needed for directed cell movement. These events may mirror the requirement for PAK2 signaling essential for the proper formation of the blood-brain barrier [6], [7].
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Affiliation(s)
- Hwee Goon Tay
- RGS (Rho GTPases in Stem Cells) Group, Institute of Medical Biology (IMB), Singapore, Singapore
| | - Yuen Wai Ng
- sGSK (Small G-Protein Signaling and Kinases) Group, Institute of Molecular and Cell Biology (IMCB), Neuroscience Research Partnership, Singapore, Singapore
| | - Ed Manser
- RGS (Rho GTPases in Stem Cells) Group, Institute of Medical Biology (IMB), Singapore, Singapore
- sGSK (Small G-Protein Signaling and Kinases) Group, Institute of Molecular and Cell Biology (IMCB), Neuroscience Research Partnership, Singapore, Singapore
- * E-mail:
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154
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Nagy II, Railo A, Rapila R, Hast T, Sormunen R, Tavi P, Räsänen J, Vainio SJ. Wnt-11 signalling controls ventricular myocardium development by patterning N-cadherin and beta-catenin expression. Cardiovasc Res 2010; 85:100-9. [PMID: 19622544 DOI: 10.1093/cvr/cvp254] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS The stage-dependent organization of the cardiomyocytes during formation of the different layers of the developing ventricular wall is critical for the establishment of a functional heart, but the instructive signals involved are still poorly known. We have addressed the potential role of Wnt-11 in the control of early ventricular myocardium assembly. METHODS AND RESULTS We demonstrate by means of expression analysis and a mouse model in which Wnt-11 function has been inactivated that Wnt-11 is expressed by the embryonic ventricular cardiomyocytes and serves as one important signal for ventricular wall development. In the absence of Wnt-11, the coordinated organization, intercellular contacts, co-localized expression of the cell adhesion components N-cadherin and beta-catenin, and the cytoskeleton of the differentiating ventricular cardiomyocytes are all disturbed. Moreover, the ventricular wall lacking Wnt-11 signalling is thinner and the expression of the Gata-4, Nkx2.5, Mef2c, ANP, and BNP genes is down-regulated relative to controls. These defects lie behind disturbed embryonic cardiac functional development, marked by an increase in the ventricular relaxation time during the early diastole. CONCLUSION We conclude that Wnt-11 signalling serves as a critical cell adhesion cue for the organization of the cardiomyocytes in the developing ventricular wall, which is essential for the establishment of a functional heart.
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Affiliation(s)
- Irina I Nagy
- Department of Medical Biochemistry and Molecular Biology, University of Oulu, 90014 Oulu, Finland
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155
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Abstract
Together with cell growth, division and death, changes in cell shape are of central importance for tissue morphogenesis during development. Cell shape is the product of a cell's material and active properties balanced by external forces. Control of cell shape, therefore, relies on both tight regulation of intracellular mechanics and the cell's physical interaction with its environment. In this review, we first discuss the biological and physical mechanisms of cell shape control. We next examine a number of developmental processes in which cell shape change - either individually or in a coordinated manner - drives embryonic morphogenesis and discuss how cell shape is controlled in these processes. Finally, we emphasize that cell shape control during tissue morphogenesis can only be fully understood by using a combination of cellular, molecular, developmental and biophysical approaches.
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Affiliation(s)
- Ewa Paluch
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
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156
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Endocytosis is required for efficient apical constriction during Xenopus gastrulation. Curr Biol 2010; 20:253-8. [PMID: 20096583 DOI: 10.1016/j.cub.2009.12.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 12/02/2009] [Accepted: 12/02/2009] [Indexed: 10/19/2022]
Abstract
Coordinated apical constriction (AC) in epithelial sheets drives tissue invagination [1, 2] and is required for diverse morphogenetic movements such as gastrulation [3], neurulation [4, 5], and organogenesis [6]. We showed previously that actomyosin contractility drives AC in Xenopus laevis bottle cells [7]; however, it remained unclear whether it does so in concert with other processes. Here we report that endocytosis-driven membrane remodeling is required for efficient AC. We found endosomes exclusively in bottle cells in the early gastrula. Disrupting endocytosis with dominant-negative dynamin or rab5 perturbed AC, with a significant decrease in constriction rate late in the process, suggesting that endocytosis operates downstream of actomyosin contractility to remove excess membrane. Additionally, disrupting endocytosis during neurulation inhibits AC in hingepoint cells, resulting in neural tube closure defects. Thus, membrane remodeling during AC could be a general mechanism to achieve efficient invagination in embryos.
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157
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The planar cell polarity protein Van Gogh-Like 2 regulates tumor cell migration and matrix metalloproteinase-dependent invasion. Cancer Lett 2010; 287:54-61. [DOI: 10.1016/j.canlet.2009.05.041] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 05/27/2009] [Accepted: 05/29/2009] [Indexed: 01/20/2023]
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158
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Line up and listen: Planar cell polarity regulation in the mammalian inner ear. Semin Cell Dev Biol 2009; 20:978-85. [PMID: 19508855 DOI: 10.1016/j.semcdb.2009.02.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 02/13/2009] [Indexed: 11/21/2022]
Abstract
The inner ear sensory organs possess extraordinary structural features necessary to conduct mechanosensory transduction for hearing and balance. Their structural beauty has fascinated scientists since the dawn of modern science and ensured a rigorous pursuit of the understanding of mechanotransduction. Sensory cells of the inner ear display unique structural features that underlie their mechanosensitivity and resolution, and represent perhaps the most distinctive form of a type of cellular polarity, known as planar cell polarity (PCP). Until recently, however, it was not known how the precise PCP of the inner ear sensory organs was achieved during development. Here, we review the PCP of the inner ear and recent advances in the quest for an understanding of its formation.
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159
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Edeling MA, Sanker S, Shima T, Umasankar PK, Höning S, Kim HY, Davidson LA, Watkins SC, Tsang M, Owen DJ, Traub LM. Structural requirements for PACSIN/Syndapin operation during zebrafish embryonic notochord development. PLoS One 2009; 4:e8150. [PMID: 19997509 PMCID: PMC2780292 DOI: 10.1371/journal.pone.0008150] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 11/05/2009] [Indexed: 11/18/2022] Open
Abstract
PACSIN/Syndapin proteins are membrane-active scaffolds that participate in endocytosis. The structure of the Drosophila Syndapin N-terminal EFC domain reveals a crescent shaped antiparallel dimer with a high affinity for phosphoinositides and a unique membrane-inserting prong upon the concave surface. Combined structural, biochemical and reverse genetic approaches in zebrafish define an important role for Syndapin orthologue, Pacsin3, in the early formation of the notochord during embryonic development. In pacsin3-morphant embryos, midline convergence of notochord precursors is defective as axial mesodermal cells fail to polarize, migrate and differentiate properly. The pacsin3 morphant phenotype of a stunted body axis and contorted trunk is rescued by ectopic expression of Drosophila Syndapin, and depends critically on both the prong that protrudes from the surface of the bowed Syndapin EFC domain and the ability of the antiparallel dimer to bind tightly to phosphoinositides. Our data confirm linkage between directional migration, endocytosis and cell specification during embryonic morphogenesis and highlight a key role for Pacsin3 in this coupling in the notochord.
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Affiliation(s)
- Melissa A. Edeling
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Subramaniam Sanker
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Takaki Shima
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - P. K. Umasankar
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Stefan Höning
- Institute of Biochemistry I and Center for Molecular Medicine, University of Cologne, Cologne, Germany
| | - Hye Y. Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Lance A. Davidson
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Simon C. Watkins
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Michael Tsang
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - David J. Owen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Linton M. Traub
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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160
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Rieger S, Senghaas N, Walch A, Köster RW. Cadherin-2 controls directional chain migration of cerebellar granule neurons. PLoS Biol 2009; 7:e1000240. [PMID: 19901980 PMCID: PMC2766073 DOI: 10.1371/journal.pbio.1000240] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 10/02/2009] [Indexed: 12/17/2022] Open
Abstract
Imaging cerebellar granule neurons in zebrafish embryos reveals a further role for Cadherin-2 in neurogenesis: regulating cohesive and directional granule cell migration via intra-membranous Cadherin-2 relocalisation and centrosome stabilization. Long distance migration of differentiating granule cells from the cerebellar upper rhombic lip has been reported in many vertebrates. However, the knowledge about the subcellular dynamics and molecular mechanisms regulating directional neuronal migration in vivo is just beginning to emerge. Here we show by time-lapse imaging in live zebrafish (Danio rerio) embryos that cerebellar granule cells migrate in chain-like structures in a homotypic glia-independent manner. Temporal rescue of zebrafish Cadherin-2 mutants reveals a direct role for this adhesion molecule in mediating chain formation and coherent migratory behavior of granule cells. In addition, Cadherin-2 maintains the orientation of cell polarization in direction of migration, whereas in Cadherin-2 mutant granule cells the site of leading edge formation and centrosome positioning is randomized. Thus, the lack of adhesion leads to impaired directional migration with a mispositioning of Cadherin-2 deficient granule cells as a consequence. Furthermore, these cells fail to differentiate properly into mature granule neurons. In vivo imaging of Cadherin-2 localization revealed the dynamics of this adhesion molecule during cell locomotion. Cadherin-2 concentrates transiently at the front of granule cells during the initiation of individual migratory steps by intramembraneous transport. The presence of Cadherin-2 in the leading edge corresponds to the observed centrosome orientation in direction of migration. Our results indicate that Cadherin-2 plays a key role during zebrafish granule cell migration by continuously coordinating cell-cell contacts and cell polarity through the remodeling of adherens junctions. As Cadherin-containing adherens junctions have been shown to be connected via microtubule fibers with the centrosome, our results offer an explanation for the mechanism of leading edge and centrosome positioning during nucleokinetic migration of many vertebrate neuronal populations. As the vertebrate nervous system develops, neurons migrate from proliferation zones to their later place of function. Adhesion molecules have been implicated as key players in regulating cellular motility. In addition, the centrosome (the main microtubule organizing center of the cell) orients into the direction of neuronal migration. In this study we assign the trans-membrane adhesion molecule Cadherin-2 with an important function in the migration of granule neurons in the cerebellum, by interconnecting adhesion with directionality of migration. Time-lapse analysis in transparent zebrafish embryos revealed that Cadherin-2 enables granule neurons to form ‘chain’-like structures during migration. In addition, this adhesion molecule stabilized the position of the centrosome at the leading edge of the migrating neuron. In vivo tracing of a fluorescent Cadherin-2 reporter molecule showed that during individual migratory steps of a granule neuron, Cadherin-2 is shifted along the cell membrane in contact with chain-migrating neighboring neurons to the front compartment of migrating cells. Cadherin-2 is a crucial component of adherens junctions, which are connected via microtubules to the centrosome. We propose that the forward translocation of Cadherin-2-containing adherens junctions stabilizes the centrosome to the cell's front. Cadherin-2 thus transmits cell-cell contact modulation into directional migration of cerebellar granule neurons.
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Affiliation(s)
- Sandra Rieger
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Niklas Senghaas
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Axel Walch
- Institute of Pathology, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
| | - Reinhard W. Köster
- Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Munich-Neuherberg, Germany
- * E-mail:
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161
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Roeth JF, Sawyer JK, Wilner DA, Peifer M. Rab11 helps maintain apical crumbs and adherens junctions in the Drosophila embryonic ectoderm. PLoS One 2009; 4:e7634. [PMID: 19862327 PMCID: PMC2763285 DOI: 10.1371/journal.pone.0007634] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 10/07/2009] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Tissue morphogenesis and organogenesis require that cells retain stable cell-cell adhesion while changing shape and moving. One mechanism to accommodate this plasticity in cell adhesion involves regulated trafficking of junctional proteins. METHODOLOGY/PRINCIPAL FINDINGS Here we explored trafficking of junctional proteins in two well-characterized model epithelia, the Drosophila embryonic ectoderm and amnioserosa. We find that DE-cadherin, the transmembrane protein of adherens junctions, is actively trafficked through putative vesicles, and appears to travel through both Rab5-positive and Rab11-positive structures. We manipulated the functions of Rab11 and Rab5 to examine the effects on junctional stability and morphogenesis. Reducing Rab11 function, either using a dominant negative construct or loss of function alleles, disrupts integrity of the ectoderm and leads to loss of adherens junctions. Strikingly, the apical junctional regulator Crumbs is lost before AJs are destabilized, while the basolateral protein Dlg remains cortical. Altering Rab5 function had less dramatic effects, not disrupting adherens junction integrity but affecting dorsal closure. CONCLUSIONS/SIGNIFICANCE We contrast our results with what others saw when disrupting other trafficking regulators, and when disrupting Rab function in other tissues; together these data suggest distinct mechanisms regulate junctional stability and plasticity in different tissues.
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Affiliation(s)
- Jeremiah F. Roeth
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jessica K. Sawyer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Daniel A. Wilner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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162
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Pulsation and stabilization: contractile forces that underlie morphogenesis. Dev Biol 2009; 341:114-25. [PMID: 19874815 DOI: 10.1016/j.ydbio.2009.10.031] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 10/18/2009] [Accepted: 10/20/2009] [Indexed: 11/20/2022]
Abstract
Embryonic development involves global changes in tissue shape and architecture that are driven by cell shape changes and rearrangements within cohesive cell sheets. Morphogenetic changes at the cell and tissue level require that cells generate forces and that these forces are transmitted between the cells of a coherent tissue. Contractile forces generated by the actin-myosin cytoskeleton are critical for morphogenesis, but the cellular and molecular mechanisms of contraction have been elusive for many cell shape changes and movements. Recent studies that have combined live imaging with computational and biophysical approaches have provided new insights into how contractile forces are generated and coordinated between cells and tissues. In this review, we discuss our current understanding of the mechanical forces that shape cells, tissues, and embryos, emphasizing the different modes of actomyosin contraction that generate various temporal and spatial patterns of force generation.
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163
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Abstract
The migration of single cells and epithelial sheets is of great importance for gastrulation and organ formation in developing embryos and, if misregulated, can have dire consequences e.g. during cancer metastasis. A keystone of cell migration is the regulation of adhesive contacts, which are dynamically assembled and disassembled via endocytosis. Here, we discuss some of the basic concepts about the function of endocytic trafficking during cell migration: transport of integrins from the cell rear to the leading edge in fibroblasts; confinement of signalling to the front of single cells by endocytic transport of growth factors; regulation of movement coherence in multicellular sheets by cadherin turnover; and shaping of extracellular chemokine gradients. Taken together, endocytosis enables migrating cells and tissues to dynamically modulate their adhesion and signalling, allowing them to efficiently migrate through their extracellular environment.
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Affiliation(s)
- Florian Ulrich
- Skirball Institute of Biomolecular Medicine, New York, USA
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164
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Roszko I, Sawada A, Solnica-Krezel L. Regulation of convergence and extension movements during vertebrate gastrulation by the Wnt/PCP pathway. Semin Cell Dev Biol 2009; 20:986-97. [PMID: 19761865 DOI: 10.1016/j.semcdb.2009.09.004] [Citation(s) in RCA: 188] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 09/05/2009] [Accepted: 09/08/2009] [Indexed: 12/18/2022]
Abstract
Vertebrate gastrulation entails massive cell movements that establish and shape the germ layers. During gastrulation, the individual cell behaviors are strictly coordinated in time and space by various signaling pathways. These pathways instruct the cells about proliferation, shape, fate and migration into proper location. Convergence and extension (C&E) movements during vertebrate gastrulation play a major role in the shaping of the embryonic body. In vertebrates, the Wnt/Planar Cell Polarity (Wnt/PCP) pathway is a key regulator of C&E movements, essential for several polarized cell behaviors, including directed cell migration, and mediolateral and radial cell intercalation. However, the molecular mechanisms underlying the acquisition of Planar Cell Polarity by highly dynamic mesenchymal cells engaged in C&E are still not well understood. Here we review new evidence implicating the Wnt/PCP pathway in specific cell behaviors required for C&E during zebrafish gastrulation, in comparison to other vertebrates. We also discuss findings on the molecular regulation and the interaction of the Wnt/PCP pathway with other signaling pathways during gastrulation movements.
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Affiliation(s)
- Isabelle Roszko
- Vanderbilt University, Department of Biological Sciences, VU Station B #351634, Nashville, TN 37235-1634, USA
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165
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Chen PI, Kong C, Su X, Stahl PD. Rab5 isoforms differentially regulate the trafficking and degradation of epidermal growth factor receptors. J Biol Chem 2009; 284:30328-38. [PMID: 19723633 DOI: 10.1074/jbc.m109.034546] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ligand-mediated endocytosis is an intricate regulatory mechanism for epidermal growth factor receptor (EGFR) signal transduction. Coordinated trafficking of EGFR ensures its temporal and spatial communication with downstream signaling effectors. We focused our work on Rab5, a monomeric GTPase shown to participate in early stages of the endocytic pathway. Rab5 has three isoforms (A, B, and C) sharing more than 90% of sequence identity. We individually ablated endogenous isoforms in HeLa cells with short interfering RNAs and examined the loss-of-function phenotypes. We found that suppression of Rab5A or 5B hampered the degradation of EGFR, whereas Rab5C depletion had very little effect. The differential delay of EGFR degradation also corresponds with retarded progression of EGFR from early to late endosomes. We investigated the activators/effectors of Rab5A that can potentially separate its potency in EGFR degradation from other isoforms and found that Rin1, a Rab5 exchange factor, preferably associated with Rab5A. Moreover, Rab5A activation is sensitive to EGF stimulation, and suppression of Rin1 diminished this sensitivity. Based on our results together with previous work showing that Rin1 interacts with signal transducing adapter molecule to facilitate the degradation of EGFR (Kong, C., Su, X., Chen, P. I., and Stahl, P. D. (2007) J. Biol. Chem. 282, 15294-15301), we hypothesize that the selective association of Rab5A and Rin1 contributes to the dominance of Rab5A in EGFR trafficking, whereas the other isoforms may have major functions unrelated to the EGFR degradation pathway.
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Affiliation(s)
- Pin-I Chen
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, Missouri 63110, USA
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166
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O'Connell MP, Weeraratna AT. Hear the Wnt Ror: how melanoma cells adjust to changes in Wnt. Pigment Cell Melanoma Res 2009; 22:724-39. [PMID: 19708915 DOI: 10.1111/j.1755-148x.2009.00627.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The interplay between canonical and non-canonical Wnt pathways in development and tumorigenesis is tightly regulated. In this review we will describe the yin and the yang of canonical and non-canonical Wnt signaling pathways during melanocyte development, and melanoma genesis. Canonical Wnt signaling, represented by Wnts such as Wnt1 and Wnt3A, signals via beta-catenin to promote melanocyte differentiation and tumor development. Non-canonical Wnt signaling, specifically Wnt5A, regulates canonical pathways, and signals to induce melanoma metastasis. This review will focus on the role of Wnt5A during melanoma progression, and its relationship to canonical Wnt signaling.
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Affiliation(s)
- Michael P O'Connell
- Laboratory of Immunology, National Institute on Aging, National Institutes of Health, Baltimore MD, USA
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167
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Regulation of endosomal membrane traffic by a Gadkin/AP-1/kinesin KIF5 complex. Proc Natl Acad Sci U S A 2009; 106:15344-9. [PMID: 19706427 DOI: 10.1073/pnas.0904268106] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Endosomes and endosomal vesicles (EVs) rapidly move along cytoskeletal filaments allowing them to exchange proteins and lipids between different endosomal compartments, lysosomes, the trans-Golgi network (TGN), and the plasma membrane. The precise mechanisms that connect membrane traffic between the TGN and perinuclear endosomal compartments with motor-protein driven transport have largely remained elusive. Here we show that Gadkin (also termed gamma-BAR), a peripheral membrane protein localized to the TGN and to TGN-derived EVs, directly associates with the clathrin adaptor AP-1 and with the motor protein kinesin KIF5, thereby potentially regulating EV dynamics. Gadkin overexpression induced the dispersion of transferrin (Tf)- and Rab4-positive EVs to the cell periphery, whereas KIF5B-depleted cells displayed a perinuclear concentration. Functional experiments suggest that the role of Gadkin as a regulator of endosomal membrane traffic critically depends on complex formation with both AP-1 and KIF5. Our data thus provide a direct molecular link between TGN-derived EVs and the microtubule-based cytoskeleton.
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168
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Mateus AM, Gorfinkiel N, Arias AM. Origin and function of fluctuations in cell behaviour and the emergence of patterns. Semin Cell Dev Biol 2009; 20:877-84. [PMID: 19665568 DOI: 10.1016/j.semcdb.2009.07.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2009] [Revised: 07/20/2009] [Accepted: 07/31/2009] [Indexed: 11/18/2022]
Abstract
Morphogenesis is the process whereby cells assemble into tissues and organs. Recent studies of this process have revealed heterogeneity of individual cell behaviours that contrasts with the deterministic activity of tissues as a whole. Here we review these observations and suggest that fluctuations and heterogeneities are a central substrate for morphogenesis and that there might exist mechanisms dedicated to the averaging of these fluctuations to ensure robust and reproducible behaviours at the tissue level.
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Affiliation(s)
- Ana M Mateus
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
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169
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Regulation of cell migration during chick gastrulation. Curr Opin Genet Dev 2009; 19:343-9. [PMID: 19647425 DOI: 10.1016/j.gde.2009.06.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/30/2009] [Accepted: 06/30/2009] [Indexed: 01/10/2023]
Abstract
Gastrulation in chick starts with large-scale cell flows in the epiblast and hypoblast, which transport the mesendoderm into the midline of the embryo to form the primitive streak. Several mechanisms such as cell-cell intercalation, deformations of the extracellular matrix and directed cell movements in response to chemical gradients have been proposed to play a role in streak formation. In the streak the epiblast cells undergo an epithelial to mesenchymal transition (EMT), which involves the breakdown of apical junctions and changes in RhoA-dependent signalling to integrins that mediated contact with the basal lamina. The collective migration of the mesendoderm away from the streak appears to be controlled by gradients of growth factors of the FGF and VEGF and Wnt families and requires N-cadherin expression. The timing and order of ingression of epiblast cells appears to be controlled by temporal and spatial colinearity of Hox gene expression in the epiblast. The mechanisms by which Hox genes control these properties remain to be resolved.
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170
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Slanchev K, Carney TJ, Stemmler MP, Koschorz B, Amsterdam A, Schwarz H, Hammerschmidt M. The epithelial cell adhesion molecule EpCAM is required for epithelial morphogenesis and integrity during zebrafish epiboly and skin development. PLoS Genet 2009; 5:e1000563. [PMID: 19609345 PMCID: PMC2700972 DOI: 10.1371/journal.pgen.1000563] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 06/16/2009] [Indexed: 12/13/2022] Open
Abstract
The aberrant expression of the transmembrane protein EpCAM is associated with tumor progression, affecting different cellular processes such as cell–cell adhesion, migration, proliferation, differentiation, signaling, and invasion. However, the in vivo function of EpCAM still remains elusive due to the lack of genetic loss-of-function studies. Here, we describe epcam (tacstd) null mutants in zebrafish. Maternal-zygotic mutants display compromised basal protrusive activity and epithelial morphogenesis in cells of the enveloping layer (EVL) during epiboly. In partial redundancy with E-cadherin (Ecad), EpCAM made by EVL cells is further required for cell–cell adhesion within the EVL and, possibly, for proper attachment of underlying deep cells to the inner surface of the EVL, thereby also affecting deep cell epiboly movements. During later development, EpCAM per se becomes indispensable for epithelial integrity within the periderm of the skin, secondarily leading to disrupted morphology of the underlying basal epidermis and moderate hyper-proliferation of skin cells. On the molecular level, EVL cells of epcam mutant embryos display reduced levels of membranous Ecad, accompanied by an enrichment of tight junction proteins and a basal extension of apical junction complexes (AJCs). Our data suggest that EpCAM acts as a partner of E-cadherin to control adhesiveness and integrity as well as plasticity and morphogenesis within simple epithelia. In addition, EpCAM is required for the interaction of the epithelia with underlying cell layers. EpCAM is a well-established marker for carcinomas of epithelial origin and a potential target for immunotherapy. In vitro analyses have implicated EpCAM in a plethora of different cellular processes, such as adhesion, motility, proliferation, differentiation, and signaling. Strikingly, depending on the context, EpCAM displayed rather opposite effects, either promoting or attenuating cell–cell adhesion versus cell migration and tissue invasion, a phenomenon described as the “double-face” of EpCAM. However, the in vivo relevance of its different effects remained largely unclear. Here, we present the first genetic analysis of EpCAM function in vivo, based on loss-of-function mutants in the zebrafish. As it is in mammals, zebrafish EpCAM is expressed in simple epithelia. Mutant embryos display defects both in epithelial morphogenesis and in epithelial integrity. Reduced epithelial morphogenesis is accompanied, and possibly caused, by an extension of apical junctional complexes and compromised basal protrusive activity. Furthermore, mutant epithelia display alterations in the relative abundance of adherence junction versus tight junction components. In addition, EpCAM tightly cooperates with E-cadherin and has a previously unrecognized trans effect on the morphogenesis and integrity of underlying cell layers. Cell differentiation and proliferation in EpCAM mutants are not, or only secondarily, affected. During later development and adulthood, EpCAM is largely dispensable, reinforcing its suitability as a target for anti-carcinoma immunotherapy with minimal side effects.
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Affiliation(s)
- Krasimir Slanchev
- Georges-Koehler-Laboratory, Max-Planck Institute of Immunobiology, Freiburg, Germany
| | - Thomas J. Carney
- Georges-Koehler-Laboratory, Max-Planck Institute of Immunobiology, Freiburg, Germany
| | - Marc P. Stemmler
- Department of Molecular Embryology, Max-Planck Institute of Immunobiology, Freiburg, Germany
| | - Birgit Koschorz
- Georges-Koehler-Laboratory, Max-Planck Institute of Immunobiology, Freiburg, Germany
| | - Adam Amsterdam
- Koch Institute for Integrative Cancer Research, Cambridge, Massachusetts, United States of America
| | - Heinz Schwarz
- Max-Planck Institute of Developmental Biology, Tübingen, Germany
| | - Matthias Hammerschmidt
- Georges-Koehler-Laboratory, Max-Planck Institute of Immunobiology, Freiburg, Germany
- Institute for Developmental Biology, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- * E-mail:
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171
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Wang Y, Steinbeisser H. Molecular basis of morphogenesis during vertebrate gastrulation. Cell Mol Life Sci 2009; 66:2263-73. [PMID: 19347571 PMCID: PMC11115717 DOI: 10.1007/s00018-009-0018-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 02/23/2009] [Accepted: 03/06/2009] [Indexed: 10/20/2022]
Abstract
Gastrulation is a crucial step in early embryogenesis. During gastrulation, a set of morphogenetic processes takes place leading to the establishment of the basic body plan and formation of primary germ layers. A rich body of knowledge about these morphogenetic processes has been accumulated over decades. The understanding of the molecular mechanism that controls the complex cell movement and inductive processes during gastrulation remains a challenge. Substantial progress has been made recently to identify and characterize pathways and molecules implicated in the modulation of morphogenesis during vertebrate gastrulation. Here, we summarize recent findings in the analysis of signaling pathways implicated in gastrulation movements, with the aim to generalize the basic molecular principles of vertebrate morphogenesis.
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Affiliation(s)
- Yingqun Wang
- Department of Cancer Biology, Abramson Family Cancer Research Institute, University of Pennsylvania, 421 Curie Blvd., Philadelphia, PA 19104, USA.
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172
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Wirtz-Peitz F, Zallen JA. Junctional trafficking and epithelial morphogenesis. Curr Opin Genet Dev 2009; 19:350-6. [PMID: 19559596 DOI: 10.1016/j.gde.2009.04.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Accepted: 04/18/2009] [Indexed: 10/20/2022]
Abstract
Epithelial monolayers are major determinants of three-dimensional tissue organization and provide the structural foundation for the body plan and all of its component organs. Epithelial cells are connected by junctional complexes containing the cell adhesion molecule E-cadherin. Adherens junctions mediate stable cohesion between cells but must be actively reorganized to allow tissue remodeling during development. Recent studies demonstrate that junctional proteins are dynamically turned over at the cell surface, even in cells that do not appear to be moving. The redistribution of E-cadherin through spatially regulated endocytosis and exocytosis contributes to cell adhesion, cell polarity, and cell rearrangement. Here we describe recent progress in understanding the roles of the vesicle transport machinery in regulating cell adhesion and junctional dynamics during epithelial morphogenesis in vivo.
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Affiliation(s)
- Frederik Wirtz-Peitz
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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173
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Málaga-Trillo E, Solis GP, Schrock Y, Geiss C, Luncz L, Thomanetz V, Stuermer CAO. Regulation of embryonic cell adhesion by the prion protein. PLoS Biol 2009; 7:e55. [PMID: 19278297 PMCID: PMC2653553 DOI: 10.1371/journal.pbio.1000055] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 01/23/2009] [Indexed: 12/22/2022] Open
Abstract
Prion proteins (PrPs) are key players in fatal neurodegenerative disorders, yet their physiological functions remain unclear, as PrP knockout mice develop rather normally. We report a strong PrP loss-of-function phenotype in zebrafish embryos, characterized by the loss of embryonic cell adhesion and arrested gastrulation. Zebrafish and mouse PrP mRNAs can partially rescue this knockdown phenotype, indicating conserved PrP functions. Using zebrafish, mouse, and Drosophila cells, we show that PrP: (1) mediates Ca+2-independent homophilic cell adhesion and signaling; and (2) modulates Ca+2-dependent cell adhesion by regulating the delivery of E-cadherin to the plasma membrane. In vivo time-lapse analyses reveal that the arrested gastrulation in PrP knockdown embryos is due to deficient morphogenetic cell movements, which rely on E-cadherin–based adhesion. Cell-transplantation experiments indicate that the regulation of embryonic cell adhesion by PrP is cell-autonomous. Moreover, we find that the local accumulation of PrP at cell contact sites is concomitant with the activation of Src-related kinases, the recruitment of reggie/flotillin microdomains, and the reorganization of the actin cytoskeleton, consistent with a role of PrP in the modulation of cell adhesion via signaling. Altogether, our data uncover evolutionarily conserved roles of PrP in cell communication, which ultimately impinge on the stability of adherens cell junctions during embryonic development. Unlike conventional pathogens, prions are infectious particles devoid of nucleic acids and composed entirely of a misfolded host protein, PrP. It is widely assumed that the neurodegeneration observed in prion disorders may be related to an aberrant function of PrP in the misfolded state. However, the normal physiological function of PrP remains poorly understood, mainly owing to the absence of clear phenotypes in mice lacking PrP. Here, we show that when PrP is depleted in zebrafish embryos, dramatic phenotypes ensue, severely affecting the development of early and late (neural) structures. We examined the mechanisms responsible for some of these defects, and found that fish and mammalian PrPs play conserved roles in cell–cell communication, by directly mediating cell adhesion and by triggering cellular signals that further modulate the function of other adhesion molecules. In the early zebrafish embryo, these activities control not only tissue integrity and cell morphology, but also the complex cellular movements that give rise to germ layers. This study describes—to our knowledge—the first known in vivo function of PrP and its molecular cellular basis, which may provide helpful insights into the role of PrP in the adult brain and its proposed connections to prion-induced neurotoxicity. Knockdown experiments in zebrafish embryos reveal that prion proteins, otherwise known for their involvement in lethal neurodegenerative disease, play important roles in cell-cell adhesion and signaling during embryonic development.
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174
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Vijayaragavan K, Szabo E, Bossé M, Ramos-Mejia V, Moon RT, Bhatia M. Noncanonical Wnt signaling orchestrates early developmental events toward hematopoietic cell fate from human embryonic stem cells. Cell Stem Cell 2009; 4:248-62. [PMID: 19265664 PMCID: PMC2742366 DOI: 10.1016/j.stem.2008.12.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 10/09/2008] [Accepted: 12/30/2008] [Indexed: 10/21/2022]
Abstract
During human development, signals that govern lineage specification versus expansion of cells committed to a cell fate are poorly understood. We demonstrate that activation of canonical Wnt signaling by Wnt3a promotes proliferation of human embryonic stem cells (hESCs)--precursors already committed to the hematopoietic lineage. In contrast, noncanonical Wnt signals, activated by Wnt11, control exit from the pluripotent state and entry toward mesoderm specification. Unique to embryoid body (EB) formation of hESCs, Wnt11 induces development and arrangement of cells expressing Brachyury that coexpress E-cadherin and Frizzled-7 (Fzd7). Knockdown of Fzd7 expression blocks Wnt11-dependent specification. Our study reveals an unappreciated role for noncanonical Wnt signaling in hESC specification that involves development of unique mesoderm precursors via morphogenic organization within human EBs.
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Affiliation(s)
- Kausalia Vijayaragavan
- Stem Cell and Cancer Research Institute, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
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175
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Liu X, Huang S, Ma J, Li C, Zhang Y, Luo L. NF-kappaB and Snail1a coordinate the cell cycle with gastrulation. ACTA ACUST UNITED AC 2009; 184:805-15. [PMID: 19307597 PMCID: PMC2699144 DOI: 10.1083/jcb.200806074] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cell cycle needs to strictly coordinate with developmental processes to ensure correct generation of the body plan and different tissues. However, the molecular mechanism underlying the coordination remains largely unknown. In this study, we investigate how the cell cycle coordinates gastrulation cell movements in zebrafish. We present a system to modulate the cell cycle in early zebrafish embryos by manipulating the geminin-Cdt1 balance. Alterations of the cell cycle change the apoptotic level during gastrulation, which correlates with the nuclear level of antiapoptotic nuclear factor κB (NF-κB). NF-κB associates with the Snail1a promoter region on the chromatin and directly activates Snail1a, an important factor controlling cell delamination, which is the initial step of mesendodermal cell movements during gastrulation. In effect, the cell cycle coordinates the delamination of mesendodermal cells through the transcription of Snail1a. Our results suggest a molecular mechanism by which NF-κB and Snail1a coordinate the cell cycle through gastrulation.
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Affiliation(s)
- Xiaolin Liu
- Key Laboratory of Aquatic Organism Reproduction and Development, Ministry of Education, Key Laboratory of Aquatic Science of Chongqing, School of Life Science, Southwest University, Beibei, Chongqing, China
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176
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Dzamba BJ, Jakab KR, Marsden M, Schwartz MA, DeSimone DW. Cadherin adhesion, tissue tension, and noncanonical Wnt signaling regulate fibronectin matrix organization. Dev Cell 2009; 16:421-32. [PMID: 19289087 DOI: 10.1016/j.devcel.2009.01.008] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 11/05/2008] [Accepted: 01/20/2009] [Indexed: 12/16/2022]
Abstract
In this study we demonstrate that planar cell polarity signaling regulates morphogenesis in Xenopus embryos in part through the assembly of the fibronectin (FN) matrix. We outline a regulatory pathway that includes cadherin adhesion and signaling through Rac and Pak, culminating in actin reorganization, myosin contractility, and tissue tension, which, in turn, directs the correct spatiotemporal localization of FN into a fibrillar matrix. Increased mechanical tension promotes FN fibril assembly in the blastocoel roof (BCR), while reduced BCR tension inhibits matrix assembly. These data support a model for matrix assembly in tissues where cell-cell adhesions play an analogous role to the focal adhesions of cultured cells by transferring to integrins the tension required to direct FN fibril formation at cell surfaces.
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Affiliation(s)
- Bette J Dzamba
- Department of Cell Biology and the Morphogenesis and Regenerative Medicine Institute, University of Virginia Health Sciences Center, PO Box 800732, Charlottesville, VA 22908, USA
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177
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Affiliation(s)
- Masazumi Tada
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Masatake Kai
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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178
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Schlessinger K, Hall A, Tolwinski N. Wnt signaling pathways meet Rho GTPases. Genes Dev 2009; 23:265-77. [PMID: 19204114 DOI: 10.1101/gad.1760809] [Citation(s) in RCA: 290] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Wnt ligands and their receptors orchestrate many essential cellular and physiological processes. During development they control differentiation, proliferation, migration, and patterning, while in the adult, they regulate tissue homeostasis, primarily through their effects on stem cell proliferation and differentiation. Underpinning these diverse biological activities is a complex set of intracellular signaling pathways that are still poorly understood. Rho GTPases have emerged as key mediators of Wnt signals, most notably in the noncanonical pathways that involve polarized cell shape changes and migrations, but also more recently in the canonical pathway leading to beta-catenin-dependent transcription. It appears that Rho GTPases integrate Wnt-induced signals spatially and temporally to promote morphological and transcriptional changes affecting cell behavior.
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Affiliation(s)
- Karni Schlessinger
- Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
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179
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Li Y, Rankin SA, Sinner D, Kenny AP, Krieg PA, Zorn AM. Sfrp5 coordinates foregut specification and morphogenesis by antagonizing both canonical and noncanonical Wnt11 signaling. Genes Dev 2009; 22:3050-63. [PMID: 18981481 DOI: 10.1101/gad.1687308] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cell identity and tissue morphogenesis are tightly orchestrated during organogenesis, but the mechanisms regulating this are poorly understood. We show that interactions between Wnt11 and the secreted Wnt antagonist secreted frizzled-related protein 5 (Sfrp5) coordinate cell fate and morphogenesis during Xenopus foregut development. sfrp5 is expressed in the surface cells of the foregut epithelium, whereas wnt11 is expressed in the underlying deep endoderm. Depletion of Sfrp5 results in reduced foregut gene expression and hypoplastic liver and ventral pancreatic buds. In addition, the ventral foregut cells lose adhesion and fail to form a polarized epithelium. We show that the cell fate and epithelial defects are due to inappropriate Wnt/beta-catenin and Wnt/PCP signaling, respectively, both mediated by Wnt11. We provide evidence that Sfrp5 locally inhibits Wnt11 to maintain early foregut identity and to allow an epithelium to form over a mass of tissue undergoing Wnt-mediated cell movements. This novel mechanism coordinating canonical and noncanonical Wnt signaling may have broad implications for organogenesis and cancer.
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Affiliation(s)
- Yan Li
- Cincinnati Children's Research Foundation and Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45229, USA
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180
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Osborne N, Brand-Arzamendi K, Ober EA, Jin SW, Verkade H, Holtzman NG, Yelon D, Stainier DYR. The spinster homolog, two of hearts, is required for sphingosine 1-phosphate signaling in zebrafish. Curr Biol 2009; 18:1882-8. [PMID: 19062281 DOI: 10.1016/j.cub.2008.10.061] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 10/19/2008] [Accepted: 10/21/2008] [Indexed: 11/20/2022]
Abstract
The bioactive lipid sphingosine 1-phosphate (S1P) and its G protein-coupled receptors play critical roles in cardiovascular, immunological, and neural development and function. Despite its importance, many questions remain about S1P signaling, including how S1P, which is synthesized intracellularly, is released from cells. Mutations in the zebrafish gene encoding the S1P receptor Miles Apart (Mil)/S1P(2) disrupt the formation of the primitive heart tube. We find that mutations of another zebrafish locus, two of hearts (toh), cause phenotypes that are morphologically indistinguishable from those seen in mil/s1p2 mutants. Positional cloning of toh reveals that it encodes a member of the Spinster-like family of putative transmembrane transporters. The biological functions of these proteins are poorly understood, although phenotypes of the Drosophila spinster and zebrafish not really started mutants suggest that these proteins may play a role in lipid trafficking. Through gain- and loss-of-function analyses, we show that toh is required for signaling by S1P(2). Further evidence indicates that Toh is involved in the trafficking or cellular release of S1P.
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Affiliation(s)
- Nick Osborne
- Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics and Human Genetics, Cardiovascular Research Institute, University of California, San Francisco, 1550 Fourth Street, San Francisco, CA 94143, USA
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181
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Hammerschmidt M, Wedlich D. Regulated adhesion as a driving force of gastrulation movements. Development 2009; 135:3625-41. [PMID: 18952908 DOI: 10.1242/dev.015701] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent data have reinforced the fundamental role of regulated cell adhesion as a force that drives morphogenesis during gastrulation. As we discuss, cell adhesion is required for all modes of gastrulation movements in all organisms. It can even be instructive in nature, but it must be tightly and dynamically regulated. The picture that emerges from the recent findings that we review here is that different modes of gastrulation movements use the same principles of adhesion regulation, while adhesion molecules themselves coordinate the intra- and extracellular changes required for directed cell locomotion.
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182
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Müller DJ, Krieg M, Alsteens D, Dufrêne YF. New frontiers in atomic force microscopy: analyzing interactions from single-molecules to cells. Curr Opin Biotechnol 2009; 20:4-13. [DOI: 10.1016/j.copbio.2009.02.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 02/10/2009] [Accepted: 02/11/2009] [Indexed: 10/21/2022]
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183
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Abstract
Morphogenesis of epithelial tissues involves various forms of reshaping of cell layers, such as invagination or bending, convergent extension, and epithelial-mesenchymal transition. At the cellular level, these processes include changes in the shape, position, and assembly pattern of cells. During such morphogenetic processes, epithelial sheets in general maintain their multicellular architecture, implying that they must engage the mechanisms to change the spatial relationship with their neighbors without disrupting the junctions. A major junctional structure in epithelial tissues is the "adherens junction," which is composed of cadherin adhesion receptors and associated proteins including F-actin. The adherens junctions are required for the firm associations between cells, as disruption of them causes disorganization of the epithelial architecture. The adherens junctions, however, appear to be a dynamic entity, allowing the rearrangement of cells within cell sheets. This dynamic nature of the adherens junctions seems to be supported by various mechanisms, such as the interactions of cadherins with actin cytoskeleton, endocytosis and recycling of cadherins, and the cooperation of cadherins with other adhesion receptors. In this chapter, we provide an overview of these mechanisms analyzed in vitro and in vivo.
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184
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Yin C, Ciruna B, Solnica-Krezel L. Chapter 7 Convergence and Extension Movements During Vertebrate Gastrulation. Curr Top Dev Biol 2009; 89:163-92. [DOI: 10.1016/s0070-2153(09)89007-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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185
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Carreira-Barbosa F, Kajita M, Kajita M, Morel V, Wada H, Okamoto H, Martinez Arias A, Fujita Y, Wilson SW, Tada M. Flamingo regulates epiboly and convergence/extension movements through cell cohesive and signalling functions during zebrafish gastrulation. Development 2008; 136:383-92. [PMID: 19091770 DOI: 10.1242/dev.026542] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During vertebrate gastrulation, the body axis is established by coordinated and directional movements of cells that include epiboly, involution, and convergence and extension (C&E). Recent work implicates a non-canonical Wnt/planar cell polarity (PCP) pathway in the regulation of C&E. The Drosophila atypical cadherin Flamingo (Fmi) and its vertebrate homologue Celsr, a 7-pass transmembrane protein with extracellular cadherin repeats, regulate several biological processes, including C&E, cochlear cell orientation, axonal pathfinding and neuronal migration. Fmi/Celsr can function together with molecules involved in PCP, such as Frizzled (Fz) and Dishevelled (Dsh), but there is also some evidence that it may act as a cell adhesion molecule in a PCP-pathway-independent manner. We show that abrogation of Celsr activity in zebrafish embryos results in epiboly defects that appear to be independent of the requirement for Celsr in PCP signalling during C&E. Using a C-terminal truncated form of Celsr that inhibits membrane presentation of wild-type Celsr through its putative pro-region, a hanging drop assay reveals that cells from embryos with compromised Celsr activity have different cohesive properties from wild-type cells. It is disruption of this ability of Celsr to affect cell cohesion that primarily leads to the in vivo epiboly defects. In addition, Lyn-Celsr, in which the intracellular domain of Celsr is fused to a membrane localisation signal (Lyn), inhibits Fz-Dsh complex formation during Wnt/PCP signalling without affecting epiboly. Fmi/Celsr therefore has a dual role in mediating two separate morphogenetic movements through its roles in mediating cell cohesion and Wnt/PCP signalling during zebrafish gastrulation.
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Affiliation(s)
- Filipa Carreira-Barbosa
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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186
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Atomic Force Microscopy: A Versatile Tool for Studying Cell Morphology, Adhesion and Mechanics. Cell Mol Bioeng 2008. [DOI: 10.1007/s12195-008-0037-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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187
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Kunwar PS, Sano H, Renault AD, Barbosa V, Fuse N, Lehmann R. Tre1 GPCR initiates germ cell transepithelial migration by regulating Drosophila melanogaster E-cadherin. ACTA ACUST UNITED AC 2008; 183:157-68. [PMID: 18824569 PMCID: PMC2557050 DOI: 10.1083/jcb.200807049] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite significant progress in identifying the guidance pathways that control cell migration, how a cell starts to move within an intact organism, acquires motility, and loses contact with its neighbors is poorly understood. We show that activation of the G protein–coupled receptor (GPCR) trapped in endoderm 1 (Tre1) directs the redistribution of the G protein Gβ as well as adherens junction proteins and Rho guanosine triphosphatase from the cell periphery to the lagging tail of germ cells at the onset of Drosophila melanogaster germ cell migration. Subsequently, Tre1 activity triggers germ cell dispersal and orients them toward the midgut for directed transepithelial migration. A transition toward invasive migration is also a prerequisite for metastasis formation, which often correlates with down-regulation of adhesion proteins. We show that uniform down-regulation of E-cadherin causes germ cell dispersal but is not sufficient for transepithelial migration in the absence of Tre1. Our findings therefore suggest a new mechanism for GPCR function that links cell polarity, modulation of cell adhesion, and invasion.
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Affiliation(s)
- Prabhat S Kunwar
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
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188
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Helenius J, Heisenberg CP, Gaub HE, Muller DJ. Single-cell force spectroscopy. J Cell Sci 2008; 121:1785-91. [PMID: 18492792 DOI: 10.1242/jcs.030999] [Citation(s) in RCA: 336] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The controlled adhesion of cells to each other and to the extracellular matrix is crucial for tissue development and maintenance. Numerous assays have been developed to quantify cell adhesion. Among these, the use of atomic force microscopy (AFM) for single-cell force spectroscopy (SCFS) has recently been established. This assay permits the adhesion of living cells to be studied in near-physiological conditions. This implementation of AFM allows unrivaled spatial and temporal control of cells, as well as highly quantitative force actuation and force measurement that is sufficiently sensitive to characterize the interaction of single molecules. Therefore, not only overall cell adhesion but also the properties of single adhesion-receptor-ligand interactions can be studied. Here we describe current implementations and applications of SCFS, as well as potential pitfalls, and outline how developments will provide insight into the forces, energetics and kinetics of cell-adhesion processes.
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Affiliation(s)
- Jonne Helenius
- Biotechnology Center, University of Technology Dresden, Germany.
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189
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Harkness L, Christiansen H, Nehlin J, Barington T, Andersen JS, Kassem M. Identification of a membrane proteomic signature for human embryonic stem cells independent of culture conditions. Stem Cell Res 2008; 1:219-27. [DOI: 10.1016/j.scr.2008.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2008] [Revised: 06/25/2008] [Accepted: 06/25/2008] [Indexed: 01/11/2023] Open
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190
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DM-GRASP/ALCAM/CD166 is required for cardiac morphogenesis and maintenance of cardiac identity in first heart field derived cells. Dev Biol 2008; 321:150-61. [DOI: 10.1016/j.ydbio.2008.06.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 05/27/2008] [Accepted: 06/05/2008] [Indexed: 11/23/2022]
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191
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Kai M, Heisenberg CP, Tada M. Sphingosine-1-phosphate receptors regulate individual cell behaviours underlying the directed migration of prechordal plate progenitor cells during zebrafish gastrulation. Development 2008; 135:3043-51. [PMID: 18701549 DOI: 10.1242/dev.020396] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During vertebrate gastrulation, cells forming the prechordal plate undergo directed migration as a cohesive cluster. Recent studies revealed that E-cadherin-mediated coherence between these cells plays an important role in effective anterior migration, and that platelet-derived growth factor (Pdgf) appears to act as a guidance cue in this process. However, the mechanisms underlying this process at the individual cell level remain poorly understood. We have identified miles apart (mil) as a suppressor of defective anterior migration of the prospective prechordal plate in silberblick (slb)/wnt11 mutant embryos, in which E-cadherin-mediated coherence of cell movement is reduced. mil encodes Edg5, a sphingosine-1-phosphate (S1P) receptor belonging to a family of five G-protein-coupled receptors (S1PRs). S1P is a lipid signalling molecule that has been implicated in regulating cytoskeletal rearrangements, cell motility and cell adhesion in a variety of cell types. We examined the roles of Mil in anterior migration of prechordal plate progenitor cells and found that, in slb embryos injected with mil-MO, cells migrate with increased motility but decreased directionality, without restoring the coherence of cell migration. This indicates that prechordal plate progenitor cells can migrate effectively as individuals, as well as in a coherent cluster of cells. Moreover, we demonstrate that Mil regulates cell motility and polarisation through Pdgf and its intracellular effecter PI3K, but modulates cell coherence independently of the Pdgf/PI3K pathway, thus co-ordinating cell motility and coherence. These results suggest that the net migration of prechordal plate progenitors is determined by different parameters, including motility, persistence and coherence.
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Affiliation(s)
- Masatake Kai
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
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192
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Sweetman D, Wagstaff L, Cooper O, Weijer C, Münsterberg A. The migration of paraxial and lateral plate mesoderm cells emerging from the late primitive streak is controlled by different Wnt signals. BMC DEVELOPMENTAL BIOLOGY 2008; 8:63. [PMID: 18541012 PMCID: PMC2435575 DOI: 10.1186/1471-213x-8-63] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 06/09/2008] [Indexed: 11/10/2022]
Abstract
BACKGROUND Co-ordinated cell movement is a fundamental feature of developing embryos. Massive cell movements occur during vertebrate gastrulation and during the subsequent extension of the embryonic body axis. These are controlled by cell-cell signalling and a number of pathways have been implicated. Here we use long-term video microscopy in chicken embryos to visualize the migration routes and movement behaviour of mesoderm progenitor cells as they emerge from the primitive streak (PS) between HH stages 7 and 10. RESULTS We observed distinct cell movement behaviours along the length of the streak and determined that this is position dependent with cells responding to environmental cues. The behaviour of cells was altered by exposing embryos or primitive streak explants to cell pellets expressing Wnt3a and Wnt5a, without affecting cell fates, thus implicating these ligands in the regulation of cell movement behaviour. Interestingly younger embryos were not responsive, suggesting that Wnt3a and Wnt5a are specifically involved in the generation of posterior mesoderm, consistent with existing mouse and zebrafish mutants. To investigate which downstream components are involved mutant forms of dishevelled (dsh) and prickle1 (pk1) were electroporated into the primitive streak. These had differential effects on the behaviour of mesoderm progenitors emerging from anterior or posterior regions of the streak, suggesting that multiple Wnt pathways are involved in controlling cell migration during extension of the body axis in amniote embryos. CONCLUSION We suggest that the distinct behaviours of paraxial and lateral mesoderm precursors are regulated by the opposing actions of Wnt5a and Wnt3a as they leave the primitive streak in neurula stage embryos. Our data suggests that Wnt5a acts via prickle to cause migration of cells from the posterior streak. In the anterior streak, this is antagonised by Wnt3a to generate non-migratory medial mesoderm.
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Affiliation(s)
- Dylan Sweetman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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193
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Kuriyama S, Mayor R. Molecular analysis of neural crest migration. Philos Trans R Soc Lond B Biol Sci 2008; 363:1349-62. [PMID: 18198151 DOI: 10.1098/rstb.2007.2252] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The neural crest (NC) cells have been called the 'explorers of the embryos' because they migrate all over the embryo where they differentiate into a variety of diverse kinds of cells. In this work, we analyse the role of different molecules controlling the migration of NC cells. First, we describe the strong similarity between the process of NC migration and metastasis in tumour cells. The epithelial-mesenchymal transition process that both kinds of cells undergo is controlled by the same molecular machinery, including cadherins, connexins, Snail and Twist genes and matrix metalloproteases. Second, we analysed the molecular signals that control the patterned migration of the cephalic and trunk NC cells. Most of the factors described so far, such as Eph/ephrins, semaphorins/neuropilins and Slit/Robo, are negative signals that prohibit the migration of NC cells into target areas of the embryo. Finally, we analyse how the direction of migration is controlled by regulation of cell polarity and how the planar cell polarity or non-canonical Wnt signalling is involved in this process.
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Affiliation(s)
- Sei Kuriyama
- Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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194
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Vervenne HBVK, Crombez KRMO, Lambaerts K, Carvalho L, Köppen M, Heisenberg CP, Van de Ven WJM, Petit MMR. Lpp is involved in Wnt/PCP signaling and acts together with Scrib to mediate convergence and extension movements during zebrafish gastrulation. Dev Biol 2008; 320:267-77. [PMID: 18582857 DOI: 10.1016/j.ydbio.2008.05.529] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 05/09/2008] [Accepted: 05/09/2008] [Indexed: 01/03/2023]
Abstract
The zyxin-related LPP protein is localized at focal adhesions and cell-cell contacts and is involved in the regulation of smooth muscle cell migration. A known interaction partner of LPP in human is the tumor suppressor protein SCRIB. Knocking down scrib expression during zebrafish embryonic development results in defects of convergence and extension (C&E) movements, which occur during gastrulation and mediate elongation of the anterior-posterior body axis. Mediolateral cell polarization underlying C&E is regulated by a noncanonical Wnt signaling pathway constituting the vertebrate planar cell polarity (PCP) pathway. Here, we investigated the role of Lpp during early zebrafish development. We show that morpholino knockdown of lpp results in defects of C&E, phenocopying noncanonical Wnt signaling mutants. Time-lapse analysis associates the defective dorsal convergence movements with a reduced ability to migrate along straight paths. In addition, expression of Lpp is significantly reduced in Wnt11 morphants and in embryos overexpressing Wnt11 or a dominant-negative form of Rho kinase 2, which is a downstream effector of Wnt11, suggesting that Lpp expression is dependent on noncanonical Wnt signaling. Finally, we demonstrate that Lpp interacts with the PCP protein Scrib in zebrafish, and that Lpp and Scrib cooperate for the mediation of C&E.
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Affiliation(s)
- Hilke B V K Vervenne
- Laboratory for Molecular Oncology, Department of Human Genetics, K.U. Leuven, Leuven, Belgium
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195
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Witze ES, Litman ES, Argast GM, Moon RT, Ahn NG. Wnt5a control of cell polarity and directional movement by polarized redistribution of adhesion receptors. Science 2008; 320:365-9. [PMID: 18420933 DOI: 10.1126/science.1151250] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mechanisms by which Wnt pathways integrate the organization of receptors, organelles, and cytoskeletal proteins to confer cell polarity and directional cell movement are incompletely understood. We show that acute responses to Wnt5a involve recruitment of actin, myosin IIB, Frizzled 3, and melanoma cell adhesion molecule into an intracellular structure in a melanoma cell line. In the presence of a chemokine gradient, this Wnt-mediated receptor-actin-myosin polarity (W-RAMP) structure accumulates asymmetrically at the cell periphery, where it triggers membrane contractility and nuclear movement in the direction of membrane retraction. The process requires endosome trafficking, is associated with multivesicular bodies, and is regulated by Wnt5a through the small guanosine triphosphatases Rab4 and RhoB. Thus, cell-autonomous mechanisms allow Wnt5a to control cell orientation, polarity, and directional movement in response to positional cues from chemokine gradients.
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Affiliation(s)
- Eric S Witze
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO80309, USA
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196
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Lecuit T. "Developmental mechanics": cellular patterns controlled by adhesion, cortical tension and cell division. HFSP JOURNAL 2008; 2:72-8. [PMID: 19404474 PMCID: PMC2645572 DOI: 10.2976/1.2896332] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Indexed: 11/19/2022]
Abstract
How embryos are shaped during development has inspired the work of many, embryologists, geneticists, but also mathematicians such as Turing, and physicists. Despite the inherent complexity of the problems it tackles, developmental biology has produced one of the most spectacular conceptual achievements, demonstrating that embryos are built with conserved molecules that orchestrate pattern and morphogenesis. As the logic of development now emerges, new challenges arise, such as how tissue mechanics is controlled. Quantitative approaches and computational models are essential to predict tissue organization and cell shapes. I review briefly how physical concepts have fueled this research in the past decades.
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Affiliation(s)
- Thomas Lecuit
- IBDML, UMR6216 CNRS-Université de la Méditerranée, Campus de Luminy case 907, 13288 Marseille Cedex 09, France
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197
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Tensile forces govern germ-layer organization in zebrafish. Nat Cell Biol 2008; 10:429-36. [PMID: 18364700 DOI: 10.1038/ncb1705] [Citation(s) in RCA: 549] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 01/28/2008] [Indexed: 01/27/2023]
Abstract
Understanding the factors that direct tissue organization during development is one of the most fundamental goals in developmental biology. Various hypotheses explain cell sorting and tissue organization on the basis of the adhesive and mechanical properties of the constituent cells. However, validating these hypotheses has been difficult due to the lack of appropriate tools to measure these parameters. Here we use atomic force microscopy (AFM) to quantify the adhesive and mechanical properties of individual ectoderm, mesoderm and endoderm progenitor cells from gastrulating zebrafish embryos. Combining these data with tissue self-assembly in vitro and the sorting behaviour of progenitors in vivo, we have shown that differential actomyosin-dependent cell-cortex tension, regulated by Nodal/TGFbeta-signalling (transforming growth factor beta), constitutes a key factor that directs progenitor-cell sorting. These results demonstrate a previously unrecognized role for Nodal-controlled cell-cortex tension in germ-layer organization during gastrulation.
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198
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Esguerra CV, Nelles L, Vermeire L, Ibrahimi A, Crawford AD, Derua R, Janssens E, Waelkens E, Carmeliet P, Collen D, Huylebroeck D. Ttrap is an essential modulator of Smad3-dependent Nodal signaling during zebrafish gastrulation and left-right axis determination. Development 2008; 134:4381-93. [PMID: 18039968 DOI: 10.1242/dev.000026] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During vertebrate development, signaling by the TGFbeta ligand Nodal is critical for mesoderm formation, correct positioning of the anterior-posterior axis, normal anterior and midline patterning, and left-right asymmetric development of the heart and viscera. Stimulation of Alk4/EGF-CFC receptor complexes by Nodal activates Smad2/3, leading to left-sided expression of target genes that promote asymmetric placement of certain internal organs. We identified Ttrap as a novel Alk4- and Smad3-interacting protein that controls gastrulation movements and left-right axis determination in zebrafish. Morpholino-mediated Ttrap knockdown increases Smad3 activity, leading to ectopic expression of snail1a and apparent repression of e-cadherin, thereby perturbing cell movements during convergent extension, epiboly and node formation. Thus, although the role of Smad proteins in mediating Nodal signaling is well-documented, the functional characterization of Ttrap provides insight into a novel Smad partner that plays an essential role in the fine-tuning of this signal transduction cascade.
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Affiliation(s)
- Camila V Esguerra
- Center for Transgene Technology and Gene Therapy, VIB, Herestraat 49, B-3000 Leuven, Belgium.
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199
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Yin C, Kiskowski M, Pouille PA, Farge E, Solnica-Krezel L. Cooperation of polarized cell intercalations drives convergence and extension of presomitic mesoderm during zebrafish gastrulation. ACTA ACUST UNITED AC 2008; 180:221-32. [PMID: 18195109 PMCID: PMC2213609 DOI: 10.1083/jcb.200704150] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During vertebrate gastrulation, convergence and extension (C&E) movements narrow and lengthen the embryonic tissues, respectively. In zebrafish, regional differences of C&E movements have been observed; however, the underlying cell behaviors are poorly understood. Using time-lapse analyses and computational modeling, we demonstrate that C&E of the medial presomitic mesoderm is achieved by cooperation of planar and radial cell intercalations. Radial intercalations preferentially separate anterior and posterior neighbors to promote extension. In knypek;trilobite noncanonical Wnt mutants, the frequencies of cell intercalations are altered and the anteroposterior bias of radial intercalations is lost. This provides evidence for noncanonical Wnt signaling polarizing cell movements between different mesodermal cell layers. We further show using fluorescent fusion proteins that during dorsal mesoderm C&E, the noncanonical Wnt component Prickle localizes at the anterior cell edge, whereas Dishevelled is enriched posteriorly. Asymmetrical localization of Prickle and Dishevelled to the opposite cell edges in zebrafish gastrula parallels their distribution in fly, and suggests that noncanonical Wnt signaling defines distinct anterior and posterior cell properties to bias cell intercalations.
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Affiliation(s)
- Chunyue Yin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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200
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Schötz EM, Burdine RD, Jülicher F, Steinberg MS, Heisenberg CP, Foty RA. Quantitative differences in tissue surface tension influence zebrafish germ layer positioning. HFSP JOURNAL 2008; 2:42-56. [PMID: 19404452 PMCID: PMC2640996 DOI: 10.2976/1.2834817] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Indexed: 11/19/2022]
Abstract
This study provides direct functional evidence that differential adhesion, measurable as quantitative differences in tissue surface tension, influences spatial positioning between zebrafish germ layer tissues. We show that embryonic ectodermal and mesendodermal tissues generated by mRNA-overexpression behave on long-time scales like immiscible fluids. When mixed in hanging drop culture, their cells segregate into discrete phases with ectoderm adopting an internal position relative to the mesendoderm. The position adopted directly correlates with differences in tissue surface tension. We also show that germ layer tissues from untreated embryos, when extirpated and placed in culture, adopt a configuration similar to those of their mRNA-overexpressing counterparts. Down-regulating E-cadherin expression in the ectoderm leads to reduced surface tension and results in phase reversal with E-cadherin-depleted ectoderm cells now adopting an external position relative to the mesendoderm. These results show that in vitro cell sorting of zebrafish mesendoderm and ectoderm tissues is specified by tissue interfacial tensions. We perform a mathematical analysis indicating that tissue interfacial tension between actively motile cells contributes to the spatial organization and dynamics of these zebrafish germ layers in vivo.
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Affiliation(s)
- Eva-Maria Schötz
- Max-Planck-Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max-Planck-Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - Rebecca D. Burdine
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08540
| | - Frank Jülicher
- Max-Planck-Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - Malcolm S. Steinberg
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08540
- New Jersey Center for Biomaterials, Rutgers University, Piscataway, New Jersey 08544
| | | | - Ramsey A. Foty
- UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901
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