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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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102
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Nyholm MK, Abdelilah-Seyfried S, Grinblat Y. A novel genetic mechanism regulates dorsolateral hinge-point formation during zebrafish cranial neurulation. J Cell Sci 2009; 122:2137-48. [PMID: 19470582 DOI: 10.1242/jcs.043471] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
During neurulation, vertebrate embryos form a neural tube (NT), the rudiment of the central nervous system. In mammals and birds, a key step in cranial NT morphogenesis is dorsolateral hinge-point (DLHP) bending, which requires an apical actomyosin network. The mechanism of DLHP formation is poorly understood, although several essential genes have been identified, among them Zic2, which encodes a zinc-finger transcription factor. We found that DLHP formation in the zebrafish midbrain also requires actomyosin and Zic function. Given this conservation, we used the zebrafish to study how genes encoding Zic proteins regulate DLHP formation. We demonstrate that the ventral zic2a expression border predicts DLHP position. Using morpholino (MO) knockdown, we show zic2a and zic5 are required for apical F-actin and active myosin II localization and junction integrity. Furthermore, myosin II activity can function upstream of junction integrity during DLHP formation, and canonical Wnt signaling, an activator of zic gene transcription, is necessary for apical active myosin II localization, junction integrity and DLHP formation. We conclude that zic genes act downstream of Wnt signaling to control cytoskeletal organization, and possibly adhesion, during neurulation. This study identifies zic2a and zic5 as crucial players in the genetic network linking patterned gene expression to morphogenetic changes during neurulation, and strengthens the utility of the zebrafish midbrain as a NT morphogenesis model.
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Affiliation(s)
- Molly K Nyholm
- Department of Anatomy, University of Wisconsin, Madison, WI 53706, USA
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103
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Lin F, Chen S, Sepich DS, Panizzi JR, Clendenon SG, Marrs JA, Hamm HE, Solnica-Krezel L. Galpha12/13 regulate epiboly by inhibiting E-cadherin activity and modulating the actin cytoskeleton. ACTA ACUST UNITED AC 2009; 184:909-21. [PMID: 19307601 PMCID: PMC2664974 DOI: 10.1083/jcb.200805148] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Epiboly spreads and thins the blastoderm over the yolk cell during zebrafish gastrulation, and involves coordinated movements of several cell layers. Although recent studies have begun to elucidate the processes that underlie these epibolic movements, the cellular and molecular mechanisms involved remain to be fully defined. Here, we show that gastrulae with altered Galpha(12/13) signaling display delayed epibolic movement of the deep cells, abnormal movement of dorsal forerunner cells, and dissociation of cells from the blastoderm, phenocopying e-cadherin mutants. Biochemical and genetic studies indicate that Galpha(12/13) regulate epiboly, in part by associating with the cytoplasmic terminus of E-cadherin, and thereby inhibiting E-cadherin activity and cell adhesion. Furthermore, we demonstrate that Galpha(12/13) modulate epibolic movements of the enveloping layer by regulating actin cytoskeleton organization through a RhoGEF/Rho-dependent pathway. These results provide the first in vivo evidence that Galpha(12/13) regulate epiboly through two distinct mechanisms: limiting E-cadherin activity and modulating the organization of the actin cytoskeleton.
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Affiliation(s)
- Fang Lin
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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104
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Cooperation of Mtmr8 with PI3K regulates actin filament modeling and muscle development in zebrafish. PLoS One 2009; 4:e4979. [PMID: 19325702 PMCID: PMC2656612 DOI: 10.1371/journal.pone.0004979] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 02/28/2009] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND It has been shown that mutations in at least four myotubularin family genes (MTM1, MTMR1, 2 and 13) are causative for human neuromuscular disorders. However, the pathway and regulative mechanism remain unknown. METHODOLOGY/PRINCIPAL FINDINGS Here, we reported a new role for Mtmr8 in neuromuscular development of zebrafish. Firstly, we cloned and characterized zebrafish Mtmr8, and revealed the expression pattern predominantly in the eye field and somites during early somitogenesis. Using morpholino knockdown, then, we observed that loss-of-function of Mtmr8 led to defects in somitogenesis. Subsequently, the possible underlying mechanism and signal pathway were examined. We first checked the Akt phosphorylation, and observed an increase of Akt phosphorylation in the morphant embryos. Furthermore, we studied the PH/G domain function within Mtmr8. Although the PH/G domain deletion by itself did not result in embryonic defect, addition of PI3K inhibitor LY294002 did give a defective phenotype in the PH/G deletion morphants, indicating that the PH/G domain was essential for Mtmr8's function. Moreover, we investigated the cooperation of Mtmr8 with PI3K in actin filament modeling and muscle development, and found that both Mtmr8-MO1 and Mtmr8-MO2+LY294002 led to the disorganization of the actin cytoskeleton. In addition, we revealed a possible participation of Mtmr8 in the Hedgehog pathway, and cell transplantation experiments showed that Mtmr8 worked in a non-cell autonomous manner in actin modeling. CONCLUSION/SIGNIFICANCE The above data indicate that a conserved functional cooperation of Mtmr8 with PI3K regulates actin filament modeling and muscle development in zebrafish, and reveal a possible participation of Mtmr8 in the Hedgehog pathway. Therefore, this work provides a new clue to study the physiological function of MTM family members.
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105
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A novel role for MAPKAPK2 in morphogenesis during zebrafish development. PLoS Genet 2009; 5:e1000413. [PMID: 19282986 PMCID: PMC2652113 DOI: 10.1371/journal.pgen.1000413] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 02/09/2009] [Indexed: 12/02/2022] Open
Abstract
One of the earliest morphogenetic processes in the development of many animals is epiboly. In the zebrafish, epiboly ensues when the animally localized blastoderm cells spread, thin over, and enclose the vegetally localized yolk. Only a few factors are known to function in this fundamental process. We identified a maternal-effect mutant, betty boop (bbp), which displays a novel defect in epiboly, wherein the blastoderm margin constricts dramatically, precisely when half of the yolk cell is covered by the blastoderm, causing the yolk cell to burst. Whole-blastoderm transplants and mRNA microinjection rescue demonstrate that Bbp functions in the yolk cell to regulate epiboly. We positionally cloned the maternal-effect bbp mutant gene and identified it as the zebrafish homolog of the serine-threonine kinase Mitogen Activated Protein Kinase Activated Protein Kinase 2, or MAPKAPK2, which was not previously known to function in embryonic development. We show that the regulation of MAPKAPK2 is conserved and p38 MAP kinase functions upstream of MAPKAPK2 in regulating epiboly in the zebrafish embryo. Dramatic alterations in calcium dynamics, together with the massive marginal constrictive force observed in bbp mutants, indicate precocious constriction of an F-actin network within the yolk cell, which first forms at 50% epiboly and regulates epiboly progression. We show that MAPKAPK2 activity and its regulator p38 MAPK function in the yolk cell to regulate the process of epiboly, identifying a new pathway regulating this cell movement process. We postulate that a p38 MAPKAPK2 kinase cascade modulates the activity of F-actin at the yolk cell margin circumference allowing the gradual closure of the blastopore as epiboly progresses. One of the earliest cell movement processes in the development of many animals is epiboly. In the zebrafish, epiboly ensues when the blastoderm cells spread over and enclose the yolk cell. Only a few factors are known to function in this fundamental process. We identified a maternal-effect mutant, betty boop (bbp), which displays a novel defect in epiboly, wherein the blastoderm margin constricts dramatically, precisely when half of the yolk cell is covered by the blastoderm, causing the yolk cell to burst. We demonstrate that Bbp functions in the yolk cell to regulate epiboly. We positionally cloned the bbp mutant gene and identified it as the serine-threonine kinase Mitogen Activated Protein Kinase Activated Protein Kinase 2, or MAPKAPK2, which was not previously known to function in embryonic development. We show that the regulation of MAPKAPK2 is conserved within a p38 MAP kinase pathway, thus identifying a new pathway in the regulation of this fundamental cell movement process. We postulate that a p38 MAPKAPK2 kinase cascade modulates F-actin contraction at the yolk cell margin circumference, allowing the gradual closure of the cells over the yolk cell as epiboly progresses.
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106
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Carvalho L, Stühmer J, Bois JS, Kalaidzidis Y, Lecaudey V, Heisenberg CP. Control of convergent yolk syncytial layer nuclear movement in zebrafish. Development 2009; 136:1305-15. [PMID: 19279138 DOI: 10.1242/dev.026922] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nuclear movements play an essential role in metazoan development. Although the intracellular transport mechanisms underlying nuclear movements have been studied in detail, relatively little is known about signals from surrounding cells and tissues controlling these movements. Here, we show that, in gastrulating zebrafish embryos, convergence movements of nuclei within the yolk syncytial layer (YSL) are guided by mesoderm and endoderm progenitors migrating along the surface of the yolk towards the dorsal side of the developing gastrula. Progenitor cells direct the convergence movements of internal yolk syncytial nuclei (iYSN) by modulating cortical flow within the YSL in which the iYSN are entrained. The effect of mesoderm and endoderm progenitors on the convergence movement of iYSN depends on the expression of E-cadherin, indicating that adhesive contact between the cells and the YSL is required for the mesendoderm-modulated YSL cortical flow mediating nuclear convergence. In summary, our data reveal a crucial function for cortical flow in the coordination of syncytial nuclear movements with surrounding cells and tissues during zebrafish gastrulation.
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Affiliation(s)
- Lara Carvalho
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
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107
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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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108
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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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109
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A targeted gain-of-function screen identifies genes affecting salivary gland morphogenesis/tubulogenesis in Drosophila. Genetics 2008; 181:543-65. [PMID: 19064711 DOI: 10.1534/genetics.108.094052] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During development individual cells in tissues undergo complex cell-shape changes to drive the morphogenetic movements required to form tissues. Cell shape is determined by the cytoskeleton and cell-shape changes critically depend on a tight spatial and temporal control of cytoskeletal behavior. We have used the formation of the salivary glands in the Drosophila embryo, a process of tubulogenesis, as an assay for identifying factors that impinge on cell shape and the cytoskeleton. To this end we have performed a gain-of-function screen in the salivary glands, using a collection of fly lines carrying EP-element insertions that allow the overexpression of downstream-located genes using the UAS-Gal4 system. We used a salivary-gland-specific fork head-Gal4 line to restrict expression to the salivary glands, in combination with reporters of cell shape and the cytoskeleton. We identified a number of genes known to affect salivary gland formation, confirming the effectiveness of the screen. In addition, we found many genes not implicated previously in this process, some having known functions in other tissues. We report the initial characterization of a subset of genes, including chickadee, rhomboid1, egalitarian, bitesize, and capricious, through comparison of gain- and loss-of-function phenotypes.
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110
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Sabel JL, d'Alençon C, O'Brien EK, Van Otterloo E, Lutz K, Cuykendall TN, Schutte BC, Houston DW, Cornell RA. Maternal Interferon Regulatory Factor 6 is required for the differentiation of primary superficial epithelia in Danio and Xenopus embryos. Dev Biol 2008; 325:249-62. [PMID: 19013452 DOI: 10.1016/j.ydbio.2008.10.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 10/16/2008] [Accepted: 10/21/2008] [Indexed: 10/21/2022]
Abstract
Early in the development of animal embryos, superficial cells of the blastula form a distinct lineage and adopt an epithelial morphology. In different animals, the fate of these primary superficial epithelial (PSE) cells varies, and it is unclear whether pathways governing segregation of blastomeres into the PSE lineage are conserved. Mutations in the gene encoding Interferon Regulatory Factor 6 (IRF6) are associated with syndromic and non-syndromic forms of cleft lip and palate, consistent with a role for Irf6 in development of oral epithelia, and mouse Irf6 targeted null mutant embryos display abnormal differentiation of oral epithelia and skin. In Danio rerio (zebrafish) and Xenopus laevis (African clawed frog) embryos, zygotic irf6 transcripts are present in many epithelial tissues including the presumptive PSE cells and maternal irf6 transcripts are present throughout all cells at the blastula stage. Injection of antisense oligonucleotides with ability to disrupt translation of irf6 transcripts caused little or no effect on development. By contrast, injection of RNA encoding a putative dominant negative Irf6 caused epiboly arrest, loss of gene expression characteristic of the EVL, and rupture of the embryo at late gastrula stage. The dominant negative Irf6 disrupted EVL gene expression in a cell autonomous fashion. These results suggest that Irf6 translated in the oocyte or unfertilized egg suffices for early development. Supporting the importance of maternal Irf6, we show that depletion of maternal irf6 transcripts in X. laevis embryos leads to gastrulation defects and rupture of the superficial epithelium. These experiments reveal a conserved role for maternally-encoded Irf6 in differentiation of a simple epithelium in X. laevis and D. rerio. This epithelium constitutes a novel model tissue in which to explore the Irf6 regulatory pathway.
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Affiliation(s)
- Jaime L Sabel
- Interdisciplinary Graduate Program in Genetics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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111
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Lai SL, Chan TH, Lin MJ, Huang WP, Lou SW, Lee SJ. Diaphanous-related formin 2 and profilin I are required for gastrulation cell movements. PLoS One 2008; 3:e3439. [PMID: 18941507 PMCID: PMC2565064 DOI: 10.1371/journal.pone.0003439] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Accepted: 09/14/2008] [Indexed: 11/18/2022] Open
Abstract
Intensive cellular movements occur during gastrulation. These cellular movements rely heavily on dynamic actin assembly. Rho with its associated proteins, including the Rho-activated formin, Diaphanous, are key regulators of actin assembly in cellular protrusion and migration. However, the function of Diaphanous in gastrulation cell movements remains unclear. To study the role of Diaphanous in gastrulation, we isolated a partial zebrafish diaphanous-related formin 2 (zdia2) clone with its N-terminal regulatory domains. The GTPase binding domain of zDia2 is highly conserved compared to its mammalian homologues. Using a yeast two-hybrid assay, we showed that zDia2 interacts with constitutively-active RhoA and Cdc42. The zdia2 mRNAs were ubiquitously expressed during early embryonic development in zebrafish as determined by RT-PCR and whole-mount in situ hybridization analyses. Knockdown of zdia2 by antisense morpholino oligonucleotides (MOs) blocked epiboly formation and convergent extension in a dose-dependent manner, whereas ectopic expression of a human mdia gene partially rescued these defects. Time-lapse recording further showed that bleb-like cellular processes of blastoderm marginal deep marginal cells and pseudopod-/filopod-like processes of prechordal plate cells and lateral cells were abolished in the zdia2 morphants. Furthermore, zDia2 acts cell-autonomously since transplanted zdia2-knockdown cells exhibited low protrusive activity with aberrant migration in wild type host embryos. Lastly, co-injection of antisense MOs of zdia2 and zebrafish profilin I (zpfn 1), but not zebrafish profilin II, resulted in a synergistic inhibition of gastrulation cell movements. These results suggest that zDia2 in conjunction with zPfn 1 are required for gastrulation cell movements in zebrafish.
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Affiliation(s)
- Shih-Lei Lai
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Tun-Hao Chan
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Meng-Ju Lin
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Wei-Pang Huang
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Show-Wan Lou
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan
| | - Shyh-Jye Lee
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- * E-mail:
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112
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Oteíza P, Köppen M, Concha ML, Heisenberg CP. Origin and shaping of the laterality organ in zebrafish. Development 2008; 135:2807-13. [DOI: 10.1242/dev.022228] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Handedness of the vertebrate body plan critically depends on transient embryonic structures/organs that generate cilia-dependent leftward fluid flow within constrained extracellular environments. Although the function of ciliated organs in laterality determination has been extensively studied, how they are formed during embryogenesis is still poorly understood. Here we show that Kupffer's vesicle (KV), the zebrafish organ of laterality, arises from a surface epithelium previously thought to adopt exclusively extra-embryonic fates. Live multi-photon confocal imaging reveals that surface epithelial cells undergo Nodal/TGFβ signalling-dependent ingression at the dorsal germ ring margin prior to gastrulation, to give rise to dorsal forerunner cells (DFCs), the precursors of KV. DFCs then migrate attached to the overlying surface epithelium and rearrange into rosette-like epithelial structures at the end of gastrulation. During early somitogenesis, these epithelial rosettes coalesce into a single rosette that differentiates into the KV with a ciliated lumen at its apical centre. Our results provide novel insights into the morphogenetic transformations that shape the laterality organ in zebrafish and suggest a conserved progenitor role of the surface epithelium during laterality organ formation in vertebrates.
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Affiliation(s)
- Pablo Oteíza
- Laboratory of Experimental Ontogeny, Program of Anatomy and Developmental Biology, Institute of Biomedical Sciences, University of Chile, Clasificador 7- Correo 7, Santiago, Chile
| | - Mathias Köppen
- Max-Planck-Institute of Molecular Cell Biology and Genetics,Pfotenhauerstr.108, 01307 Dresden, Germany
| | - Miguel L. Concha
- Laboratory of Experimental Ontogeny, Program of Anatomy and Developmental Biology, Institute of Biomedical Sciences, University of Chile, Clasificador 7- Correo 7, Santiago, Chile
| | - Carl-Philipp Heisenberg
- Max-Planck-Institute of Molecular Cell Biology and Genetics,Pfotenhauerstr.108, 01307 Dresden, Germany
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113
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Honda H, Nagai T, Tanemura M. Two different mechanisms of planar cell intercalation leading to tissue elongation. Dev Dyn 2008; 237:1826-36. [DOI: 10.1002/dvdy.21609] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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114
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Krens SG, He S, Lamers GE, Meijer AH, Bakkers J, Schmidt T, Spaink HP, Snaar-Jagalska BE. Distinct functions for ERK1 and ERK2 in cell migration processes during zebrafish gastrulation. Dev Biol 2008; 319:370-83. [DOI: 10.1016/j.ydbio.2008.04.032] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 04/11/2008] [Accepted: 04/28/2008] [Indexed: 11/28/2022]
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115
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Ivanov AI, Hopkins AM, Brown GT, Gerner-Smidt K, Babbin BA, Parkos CA, Nusrat A. Myosin II regulates the shape of three-dimensional intestinal epithelial cysts. J Cell Sci 2008; 121:1803-14. [PMID: 18460584 DOI: 10.1242/jcs.015842] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The development of luminal organs begins with the formation of spherical cysts composed of a single layer of epithelial cells. Using a model three-dimensional cell culture, this study examines the role of a cytoskeletal motor, myosin II, in cyst formation. Caco-2 and SK-CO15 intestinal epithelial cells were embedded into Matrigel, and myosin II was inhibited by blebbistatin or siRNA-mediated knockdown. Whereas control cells formed spherical cysts with a smooth surface, inhibition of myosin II induced the outgrowth of F-actin-rich surface protrusions. The development of these protrusions was abrogated after inhibition of F-actin polymerization or of phospholipase C (PLC) activity, as well as after overexpression of a dominant-negative ADF/cofilin. Surface protrusions were enriched in microtubules and their formation was prevented by microtubule depolymerization. Myosin II inhibition caused a loss of peripheral F-actin bundles and a submembranous extension of cortical microtubules. Our findings suggest that inhibition of myosin II eliminates the cortical F-actin barrier, allowing microtubules to reach and activate PLC at the plasma membrane. PLC-dependent stimulation of ADF/cofilin creates actin-filament barbed ends and promotes the outgrowth of F-actin-rich protrusions. We conclude that myosin II regulates the spherical shape of epithelial cysts by controlling actin polymerization at the cyst surface.
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Affiliation(s)
- Andrei I Ivanov
- Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322, USA.
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116
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Zallen JA, Blankenship JT. Multicellular dynamics during epithelial elongation. Semin Cell Dev Biol 2008; 19:263-70. [PMID: 18343171 PMCID: PMC2699999 DOI: 10.1016/j.semcdb.2008.01.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 12/21/2007] [Accepted: 01/23/2008] [Indexed: 12/24/2022]
Abstract
The reorganization of multicellular populations to produce an elongated tissue structure is a conserved mechanism for shaping the body axis and several organ systems. In the Drosophila germband epithelium, this process is accompanied by the formation of a planar polarized network of junctional and cytoskeletal proteins in response to striped patterns of gene expression. Actomyosin cables and adherens junctions are dynamically remodeled during intercalation, providing the basis for polarized cell behavior. Quantitative analysis of cell behavior in living embryos reveals unexpected cell population dynamics that include the formation of multicellular rosette structures as well as local neighbor exchange.
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Affiliation(s)
- Jennifer A Zallen
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA.
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117
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The influence of cell mechanics, cell-cell interactions, and proliferation on epithelial packing. Curr Biol 2008; 17:2095-104. [PMID: 18082406 DOI: 10.1016/j.cub.2007.11.049] [Citation(s) in RCA: 751] [Impact Index Per Article: 46.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 10/19/2007] [Accepted: 11/09/2007] [Indexed: 11/20/2022]
Abstract
BACKGROUND Epithelial junctional networks assume packing geometries characterized by different cell shapes, neighbor number distributions and areas. The development of specific packing geometries is tightly controlled; in the Drosophila wing epithelium, cells convert from an irregular to a hexagonal array shortly before hair formation. Packing geometry is determined by developmental mechanisms that likely control the biophysical properties of cells and their interactions. RESULTS To understand how physical cellular properties and proliferation determine cell-packing geometries, we use a vertex model for the epithelial junctional network in which cell packing geometries correspond to stable and stationary network configurations. The model takes into account cell elasticity and junctional forces arising from cortical contractility and adhesion. By numerically simulating proliferation, we generate different network morphologies that depend on physical parameters. These networks differ in polygon class distribution, cell area variation, and the rate of T1 and T2 transitions during growth. Comparing theoretical results to observed cell morphologies reveals regions of parameter space where calculated network morphologies match observed ones. We independently estimate parameter values by quantifying network deformations caused by laser ablating individual cell boundaries. CONCLUSIONS The vertex model accounts qualitatively and quantitatively for the observed packing geometry in the wing disc and its response to perturbation by laser ablation. Epithelial packing geometry is a consequence of both physical cellular properties and the disordering influence of proliferation. The occurrence of T2 transitions during network growth suggests that elimination of cells from the proliferating disc epithelium may be the result of junctional force balances.
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118
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Recent papers on zebrafish and other aquarium fish models. Zebrafish 2008; 3:387-98. [PMID: 18377219 DOI: 10.1089/zeb.2006.3.387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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119
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Shook DR, Keller R. Morphogenic machines evolve more rapidly than the signals that pattern them: lessons from amphibians. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2008; 310:111-35. [PMID: 18041048 DOI: 10.1002/jez.b.21204] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The induction of mesoderm and the patterning of its dorsal-ventral and anterior-posterior axes seems to be relatively conserved throughout the chordates, as do the morphogenic movements that produce a phylotypic stage embryo. What is not conserved is the initial embryonic architecture of the fertilized egg, and the specific cell behaviors used to drive mesoderm morphogenesis. How then do conserved patterning pathways adapt to diverse architectures and where do they diverge to direct the different cell behaviors used to shape the phylotypic body plan? Amphibians in particular, probably because of their broad range of reproductive strategies, show diverse embryonic architectures across their class and use diverse cell behaviors during their early morphogenesis, making them an interesting comparative group. We examine three examples from our work on amphibians that show variations in the use of cell behaviors to drive the morphogenesis of the same tissues. We also consider possible points where the conserved patterning pathways might diverge to produce different cell behaviors.
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Affiliation(s)
- David R Shook
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904-4328, USA.
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120
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Ca2+ channel-independent requirement for MAGUK family CACNB4 genes in initiation of zebrafish epiboly. Proc Natl Acad Sci U S A 2008; 105:198-203. [PMID: 18172207 DOI: 10.1073/pnas.0707948105] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CACNB genes encode membrane-associated guanylate kinase (MAGUK) proteins once thought to function exclusively as auxiliary beta subunits in assembly and gating of voltage-gated Ca(2+) channels. Here, we report that zygotic deficiency of zebrafish beta4 protein blocks initiation of epiboly, the first morphogenetic movement of teleost embryos. Reduced beta4 function in the yolk syncytial layer (YSL) leads to abnormal division and dispersal of yolk syncytial nuclei, blastoderm retraction, and death, effects highly similar to microtubule disruption by nocodazole. Epiboly is restored by coinjection of human beta4 cRNA or, surprisingly, by mutant cRNA encoding beta4 subunits incapable of binding to Ca(2+) channel alpha1 subunits. This study defines a YSL-driven zygotic mechanism essential for epiboly initiation and reveals a Ca(2+) channel-independent beta4 protein function potentially involving the cytoskeleton.
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121
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Extraembryonic development in insects and the acrobatics of blastokinesis. Dev Biol 2008; 313:471-91. [DOI: 10.1016/j.ydbio.2007.11.004] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 10/11/2007] [Accepted: 11/02/2007] [Indexed: 01/04/2023]
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122
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Rohlfs M, Arasada R, Batsios P, Janzen J, Schleicher M. The Ste20-like kinase SvkA ofDictyostelium discoideumis essential for late stages of cytokinesis. J Cell Sci 2007; 120:4345-54. [DOI: 10.1242/jcs.012179] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of the social amoeba Dictyostelium discoideum encodes ∼285 kinases, which represents ∼2.6% of the total genome and suggests a signaling complexity similar to that of yeasts and humans. The behavior of D. discoideum as an amoeba and during development relies heavily on fast rearrangements of the actin cytoskeleton. Here, we describe the knockout phenotype of the svkA gene encoding severin kinase, a homolog of the human MST3, MST4 and YSK1 kinases. SvkA-knockout cells show drastic defects in cytokinesis, development and directed slug movement. The defect in cytokinesis is most prominent, leading to multinucleated cells sometimes with >30 nuclei. The defect arises from the frequent inability of svkA-knockout cells to maintain symmetry during formation of the cleavage furrow and to sever the last cytosolic connection. We demonstrate that GFP-SvkA is enriched at the centrosome and localizes to the midzone during the final stage of cell division. This distribution is mediated by the C-terminal half of the kinase, whereas a rescue of the phenotypic changes requires the active N-terminal kinase domain as well. The data suggest that SvkA is part of a regulatory pathway from the centrosome to the midzone, thus regulating the completion of cell division.
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Affiliation(s)
- Meino Rohlfs
- Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, 80336 München, Germany
| | - Rajesh Arasada
- Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, 80336 München, Germany
| | - Petros Batsios
- Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, 80336 München, Germany
| | - Julia Janzen
- Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, 80336 München, Germany
| | - Michael Schleicher
- Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, 80336 München, Germany
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123
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Wilkins SJ, Yoong S, Verkade H, Mizoguchi T, Plowman SJ, Hancock JF, Kikuchi Y, Heath JK, Perkins AC. Mtx2 directs zebrafish morphogenetic movements during epiboly by regulating microfilament formation. Dev Biol 2007; 314:12-22. [PMID: 18154948 DOI: 10.1016/j.ydbio.2007.10.050] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 10/17/2007] [Accepted: 10/19/2007] [Indexed: 11/16/2022]
Abstract
The homeobox transcription factor Mtx2 is essential for epiboly, the first morphogenetic movement of gastrulation in zebrafish. Morpholino knockdown of Mtx2 results in stalling of epiboly and lysis due to yolk rupture. However, the mechanism of Mtx2 action is unknown. The role of mtx2 is surprising as most mix/bix family genes are thought to have roles in mesendoderm specification. Using a transgenic sox17-promoter driven EGFP line, we show that Mtx2 is not required for endoderm specification but is required for correct morphogenetic movements of endoderm and axial mesoderm. During normal zebrafish development, mtx2 is expressed at both the blastoderm margin and in the zebrafish equivalent of visceral endoderm, the extra-embryonic yolk syncytial layer (YSL). We show that formation of the YSL is not Mtx2 dependent, but that Mtx2 directs spatial arrangement of YSL nuclei. Furthermore, we demonstrate that Mtx2 knockdown results in loss of the YSL F-actin ring, a microfilament structure previously shown to be necessary for epiboly progression. In summary, we propose that Mtx2 acts within the YSL to regulate morphogenetic movements of both embryonic and extra-embryonic tissues, independently of cell fate specification.
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Affiliation(s)
- Simon J Wilkins
- Institute for Molecular Bioscience, University of Queensland, Brisbane, 4072, Australia
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124
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Lachnit M, Kur E, Driever W. Alterations of the cytoskeleton in all three embryonic lineages contribute to the epiboly defect of Pou5f1/Oct4 deficient MZspg zebrafish embryos. Dev Biol 2007; 315:1-17. [PMID: 18215655 DOI: 10.1016/j.ydbio.2007.10.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2007] [Revised: 10/03/2007] [Accepted: 10/05/2007] [Indexed: 01/23/2023]
Abstract
Pou5f1/Oct4 is a transcription factor required for pluripotency of embryonic stem cells in mammals. Zebrafish pou5f1 deficient maternal and zygotic spiel ohne grenzen (MZspg) mutant embryos develop severe gastrulation defects, are dorsalized, and defective in endoderm formation. Here we analyze in detail gastrulation defects, which are manifested by a severe delay in epiboly progression. All three embryonic lineages in MZspg embryos behave abnormally during epiboly: the yolk cell forms an altered array of cortical microtubules and F-Actin, with large patches of microtubule free areas; the enveloping layer (EVL) is delayed in the coordinated cell shape changes of marginal cells, that may be mediated by F-Actin; the deep layer cells (DEL), forming the embryo proper, are non-autonomously affected in their motility and do not enter the space opening by epiboly of the EVL. Analysis of adhesiveness as well as high resolution in vivo time lapse image analysis of DEL cells suggests changed adhesive properties and inability to migrate properly on EVL and yolk syncytial layer (YSL) surfaces. Our data further reveal that during epiboly the EVL may actively probe the YSL by filopodia formation, rather than just being passively pulled vegetalwards. Our findings on the effect of Pou5f1 on cell behavior may be relevant to understand stem cell behavior and tumorigenesis involving Pou5f1.
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Affiliation(s)
- Martina Lachnit
- Department of Developmental Biology, Institute Biology 1, University of Freiburg, 79104 Freiburg, Germany
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125
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Boettner B, Van Aelst L. The Rap GTPase activator Drosophila PDZ-GEF regulates cell shape in epithelial migration and morphogenesis. Mol Cell Biol 2007; 27:7966-80. [PMID: 17846121 PMCID: PMC2169160 DOI: 10.1128/mcb.01275-07] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epithelial morphogenesis is characterized by an exquisite control of cell shape and position. Progression through dorsal closure in Drosophila gastrulation depends on the ability of Rap1 GTPase to signal through the adherens junctional multidomain protein Canoe. Here, we provide genetic evidence that epithelial Rap activation and Canoe effector usage are conferred by the Drosophila PDZ-GEF (dPDZ-GEF) exchange factor. We demonstrate that dPDZ-GEF/Rap/Canoe signaling modulates cell shape and apicolateral cell constriction in embryonic and wing disc epithelia. In dPDZ-GEF mutant embryos with strong dorsal closure defects, cells in the lateral ectoderm fail to properly elongate. Postembryonic dPDZ-GEF mutant cells generated in mosaic tissue display a striking extension of lateral cell perimeters in the proximity of junctional complexes, suggesting a loss of normal cell contractility. Furthermore, our data indicate that dPDZ-GEF signaling is linked to myosin II function. Both dPDZ-GEF and cno show strong genetic interactions with the myosin II-encoding gene, and myosin II distribution is severely perturbed in epithelia of both mutants. These findings provide the first insight into the molecular machinery targeted by Rap signaling to modulate epithelial plasticity. We propose that dPDZ-GEF-dependent signaling functions as a rheostat linking Rap activity to the regulation of cell shape in epithelial morphogenesis at different developmental stages.
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Affiliation(s)
- Benjamin Boettner
- Cold Spring Harbor Laboratory, Watson School of Biological Sciences, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
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126
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Lee RHK, Iioka H, Ohashi M, Iemura SI, Natsume T, Kinoshita N. XRab40 and XCullin5 form a ubiquitin ligase complex essential for the noncanonical Wnt pathway. EMBO J 2007; 26:3592-606. [PMID: 17627283 PMCID: PMC1949004 DOI: 10.1038/sj.emboj.7601781] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Accepted: 06/11/2007] [Indexed: 12/17/2022] Open
Abstract
Rab GTPases are key regulators of intracellular membrane trafficking. We sought to elucidate the roles of Rab GTPases in Xenopus gastrulation, and found that a Xenopus homolog of Rab40 (XRab40) is required for normal gastrulation. XRab40 is localized at the Golgi apparatus and interacts with ElonginB/C and Cullin5 to form a ubiquitin ligase. XRab40/XCullin5 functions cooperatively and regulates the ubiquitination and localization of Rap2 GTPase. Furthermore, XRab40/XCullin5 regulates the membrane localization of Dishevelled (Dsh), a key signaling molecule in the Wnt pathway, through Rap2 and its effector Misshapen/Nck-interacting kinase (XMINK). XMINK interacts with Dsh, and is translocated to the plasma membrane by Wnt activation. We propose a novel signaling cascade consisting of XRab40/XCullin5, Rap2 and XMINK, which plays a crucial role in the regulation of the noncanonical Wnt pathway.
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Affiliation(s)
- Rebecca Hui Kwan Lee
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
- Department of Molecular Biomechanics, The Graduate University for Advanced Studies; Okazaki, Aichi, Japan
| | - Hidekazu Iioka
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Masato Ohashi
- Okazaki Institute for Integrative Bioscience, National Institute of Natural Sciences, Okazaki, Japan
| | - Shun-ichiro Iemura
- National Institutes of Advanced Industrial Science and Technology; Biological Information Research Center; Tokyo, Japan
| | - Tohru Natsume
- National Institutes of Advanced Industrial Science and Technology; Biological Information Research Center; Tokyo, Japan
| | - Noriyuki Kinoshita
- Department of Developmental Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
- Department of Molecular Biomechanics, The Graduate University for Advanced Studies; Okazaki, Aichi, Japan
- Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan. Tel.: +81 564 55 7573; Fax: +81 564 55 7571; E-mail:
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127
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Abstract
Planar polarity is a global, tissue-level phenomenon that coordinates cell behavior in a two-dimensional plane. The Frizzled/planar cell polarity (PCP) and anterior-posterior (AP) patterning systems for planar polarity operate in a variety of cell types and provide direction to cells with different morphologies and behaviors. These two systems involve different sets of proteins but both use directional cues provided locally by communication between neighboring cells. This review describes our current understanding of the mechanisms that transmit directional signals from cell to cell and compares the strategies for generating global systems of spatial information in stationary and dynamic cell populations.
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Affiliation(s)
- Jennifer A Zallen
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA.
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128
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Rohde LA, Heisenberg CP. Zebrafish Gastrulation: Cell Movements, Signals, and Mechanisms. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 261:159-92. [PMID: 17560282 DOI: 10.1016/s0074-7696(07)61004-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gastrulation is a morphogenetic process that results in the formation of the embryonic germ layers. Here we detail the major cell movements that occur during zebrafish gastrulation: epiboly, internalization, and convergent extension. Although gastrulation is known to be regulated by signaling pathways such as the Wnt/planar cell polarity pathway, many questions remain about the underlying molecular and cellular mechanisms. Key factors that may play a role in gastrulation cell movements are cell adhesion and cytoskeletal rearrangement. In addition, some of the driving force for gastrulation may derive from tissue interactions such as those described between the enveloping layer and the yolk syncytial layer. Future exploration of gastrulation mechanisms relies on the development of sensitive and quantitative techniques to characterize embryonic germ-layer properties.
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Affiliation(s)
- Laurel A Rohde
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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129
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In Brief. Nat Rev Mol Cell Biol 2006. [DOI: 10.1038/nrm2000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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