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Montembault E, Deduyer I, Claverie MC, Bouit L, Tourasse NJ, Dupuy D, McCusker D, Royou A. Two RhoGEF isoforms with distinct localisation control furrow position during asymmetric cell division. Nat Commun 2023; 14:3209. [PMID: 37268622 DOI: 10.1038/s41467-023-38912-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 05/19/2023] [Indexed: 06/04/2023] Open
Abstract
Cytokinesis partitions cellular content between daughter cells. It relies on the formation of an acto-myosin contractile ring, whose constriction induces the ingression of the cleavage furrow between the segregated chromatids. Rho1 GTPase and its RhoGEF (Pbl) are essential for this process. However, how Rho1 is regulated to sustain furrow ingression while maintaining correct furrow position remains poorly defined. Here, we show that during asymmetric division of Drosophila neuroblasts, Rho1 is controlled by two Pbl isoforms with distinct localisation. Spindle midzone- and furrow-enriched Pbl-A focuses Rho1 at the furrow to sustain efficient ingression, while Pbl-B pan-plasma membrane localization promotes the broadening of Rho1 activity and the subsequent enrichment of myosin on the entire cortex. This enlarged zone of Rho1 activity is critical to adjust furrow position, thereby preserving correct daughter cell size asymmetry. Our work highlights how the use of isoforms with distinct localisation makes an essential process more robust.
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Affiliation(s)
- Emilie Montembault
- CNRS, UMR5095, University of Bordeaux, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
- CNRS, UMR5095, University of Bordeaux, Institut de Biologie et Génétique Cellulaire, 1 rue Camille Saint-Saëns, 33077, Bordeaux, France
| | - Irène Deduyer
- CNRS, UMR5095, University of Bordeaux, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
- CNRS, UMR5095, University of Bordeaux, Institut de Biologie et Génétique Cellulaire, 1 rue Camille Saint-Saëns, 33077, Bordeaux, France
| | - Marie-Charlotte Claverie
- CNRS, UMR5095, University of Bordeaux, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
- CNRS, UMR5095, University of Bordeaux, Institut de Biologie et Génétique Cellulaire, 1 rue Camille Saint-Saëns, 33077, Bordeaux, France
| | - Lou Bouit
- CNRS, UMR5095, University of Bordeaux, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
- CNRS, UMR5297, University of Bordeaux, 146 Rue Léo Saignat, 33076, Bordeaux, France
| | - Nicolas J Tourasse
- University of Bordeaux, INSERM, U1212, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
| | - Denis Dupuy
- University of Bordeaux, INSERM, U1212, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
| | - Derek McCusker
- CNRS, UMR5095, University of Bordeaux, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France
- CNRS, UMR5095, University of Bordeaux, Institut de Biologie et Génétique Cellulaire, 1 rue Camille Saint-Saëns, 33077, Bordeaux, France
| | - Anne Royou
- CNRS, UMR5095, University of Bordeaux, Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, 33607, Pessac, France.
- CNRS, UMR5095, University of Bordeaux, Institut de Biologie et Génétique Cellulaire, 1 rue Camille Saint-Saëns, 33077, Bordeaux, France.
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Ayoub M, David LM, Shklyar B, Hakim-Mishnaevski K, Kurant E. Drosophila FGFR/Htl signaling shapes embryonic glia to phagocytose apoptotic neurons. Cell Death Discov 2023; 9:90. [PMID: 36898998 PMCID: PMC10006210 DOI: 10.1038/s41420-023-01382-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 02/19/2023] [Accepted: 02/24/2023] [Indexed: 03/12/2023] Open
Abstract
Glial phagocytosis of apoptotic neurons is crucial for development and proper function of the central nervous system. Relying on transmembrane receptors located on their protrusions, phagocytic glia recognize and engulf apoptotic debris. Like vertebrate microglia, Drosophila phagocytic glial cells form an elaborate network in the developing brain to reach and remove apoptotic neurons. However, the mechanisms controlling creation of the branched morphology of these glial cells critical for their phagocytic ability remain unknown. Here, we demonstrate that during early embryogenesis, the Drosophila fibroblast growth factor receptor (FGFR) Heartless (Htl) and its ligand Pyramus are essential in glial cells for the formation of glial extensions, the presence of which strongly affects glial phagocytosis of apoptotic neurons during later stages of embryonic development. Reduction in Htl pathway activity results in shorter lengths and lower complexity of glial branches, thereby disrupting the glial network. Our work thus illuminates the important role Htl signaling plays in glial subcellular morphogenesis and in establishing glial phagocytic ability.
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Affiliation(s)
- Malak Ayoub
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Li-Mor David
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Boris Shklyar
- Bioimaging Unit, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Ketty Hakim-Mishnaevski
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel
| | - Estee Kurant
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, 3498838, Haifa, Israel.
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3
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Lemke S, Kale G, Urbansky S. Comparing gastrulation in flies: Links between cell biology and the evolution of embryonic morphogenesis. Mech Dev 2020. [DOI: 10.1016/j.mod.2020.103648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Stepanik V, Sun J, Stathopoulos A. FGF Pyramus Has a Transmembrane Domain and Cell-Autonomous Function in Polarity. Curr Biol 2020; 30:3141-3153.e5. [PMID: 32619487 DOI: 10.1016/j.cub.2020.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/13/2020] [Accepted: 06/01/2020] [Indexed: 11/18/2022]
Abstract
Most fibroblast growth factors (FGFs) function as receptor ligands through their conserved FGF domain, but sequences outside this domain vary and are not well studied. This core domain of 120 amino acids (aa) is flanked in all FGFs by highly divergent amino-terminal and carboxy-terminal sequences of variable length. Drosophila has fewer FGF genes, with only three identified to date, pyramus (pyr), thisbe (ths), and branchless (bnl), and all three encoding relatively large FGF proteins (∼80 kDa). We hypothesized that the longer FGF proteins present in Drosophila and other organisms may relate to an ancestral form, in which multiple functions or regulatory properties are present within a single polypeptide. Here, we focused analysis on Pyr, finding that it harbors a transmembrane domain (TMD) and extended C-terminal intracellular domain containing a degron. The intracellular portion limits Pyr levels, whereas the TMD promotes spatial precision in the paracrine activation of Heartless FGF receptor. Additionally, degron deletion mutants that upregulate Pyr exhibit cell polarity defects that lead to invagination defects at gastrulation, demonstrating a previously uncharacterized cell-autonomous role. In summary, our data show that Pyr is the first demonstrated transmembrane FGF, that it has both extracellular and intracellular functions, and that spatial distribution and levels of this particular FGF protein are tightly regulated. Our results suggest that other FGFs may be membrane tethered or multifunctional like Pyr.
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Affiliation(s)
- Vincent Stepanik
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Jingjing Sun
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Angelike Stathopoulos
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
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Gheisari E, Aakhte M, Müller HAJ. Gastrulation in Drosophila melanogaster: Genetic control, cellular basis and biomechanics. Mech Dev 2020; 163:103629. [PMID: 32615151 DOI: 10.1016/j.mod.2020.103629] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 06/08/2020] [Accepted: 06/24/2020] [Indexed: 01/31/2023]
Abstract
Gastrulation is generally understood as the morphogenetic processes that result in the spatial organization of the blastomere into the three germ layers, ectoderm, mesoderm and endoderm. This review summarizes our current knowledge of the morphogenetic mechanisms in Drosophila gastrulation. In addition to the events that drive mesoderm invagination and germband elongation, we pay particular attention to other, less well-known mechanisms including midgut invagination, cephalic furrow formation, dorsal fold formation, and mesoderm layer formation. This review covers topics ranging from the identification and functional characterization of developmental and morphogenetic control genes to the analysis of the physical properties of cells and tissues and the control of cell and tissue mechanics of the morphogenetic movements in the gastrula.
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Affiliation(s)
- Elham Gheisari
- Institute for Biology, Dept. Developmental Genetics, University of Kassel, Germany
| | - Mostafa Aakhte
- Institute for Biology, Dept. Developmental Genetics, University of Kassel, Germany
| | - H-Arno J Müller
- Institute for Biology, Dept. Developmental Genetics, University of Kassel, Germany.
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Sun J, Macabenta F, Akos Z, Stathopoulos A. Collective Migrations of Drosophila Embryonic Trunk and Caudal Mesoderm-Derived Muscle Precursor Cells. Genetics 2020; 215:297-322. [PMID: 32487692 PMCID: PMC7268997 DOI: 10.1534/genetics.120.303258] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 04/17/2020] [Indexed: 01/06/2023] Open
Abstract
Mesoderm migration in the Drosophila embryo is a highly conserved, complex process that is required for the formation of specialized tissues and organs, including the somatic and visceral musculature. In this FlyBook chapter, we will compare and contrast the specification and migration of cells originating from the trunk and caudal mesoderm. Both cell types engage in collective migrations that enable cells to achieve new positions within developing embryos and form distinct tissues. To start, we will discuss specification and early morphogenetic movements of the presumptive mesoderm, then focus on the coordinate movements of the two subtypes trunk mesoderm and caudal visceral mesoderm, ending with a comparison of these processes including general insights gained through study.
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Affiliation(s)
- Jingjing Sun
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Frank Macabenta
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Zsuzsa Akos
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Angelike Stathopoulos
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
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Yang S, Weske A, Du Y, Valera JM, Jones KL, Johnson AN. FGF signaling directs myotube guidance by regulating Rac activity. Development 2020; 147:dev.183624. [PMID: 31932350 DOI: 10.1242/dev.183624] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 12/27/2019] [Indexed: 01/25/2023]
Abstract
Nascent myotubes undergo a dramatic morphological transformation during myogenesis, in which the myotubes elongate over several cell diameters and are directed to the correct muscle attachment sites. Although this process of myotube guidance is essential to pattern the musculoskeletal system, the mechanisms that control myotube guidance remain poorly understood. Using transcriptomics, we found that components of the Fibroblast Growth Factor (FGF) signaling pathway were enriched in nascent myotubes in Drosophila embryos. Null mutations in the FGF receptor heartless (htl), or its ligands, caused significant myotube guidance defects. The FGF ligand Pyramus is expressed broadly in the ectoderm, and ectopic Pyramus expression disrupted muscle patterning. Mechanistically, Htl regulates the activity of Rho/Rac GTPases in nascent myotubes and effects changes in the actin cytoskeleton. FGF signals are thus essential regulators of myotube guidance that act through cytoskeletal regulatory proteins to pattern the musculoskeletal system.
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Affiliation(s)
- Shuo Yang
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Allison Weske
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Yingqiu Du
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Juliana M Valera
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Kenneth L Jones
- Hematology, Oncology, and Bone Marrow Transplant, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Aaron N Johnson
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
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Beati H, Langlands A, Ten Have S, Müller HAJ. SILAC-based quantitative proteomic analysis of Drosophila gastrula stage embryos mutant for fibroblast growth factor signalling. Fly (Austin) 2019; 14:10-28. [PMID: 31873056 DOI: 10.1080/19336934.2019.1705118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Quantitative proteomic analyses in combination with genetics provide powerful tools in developmental cell signalling research. Drosophila melanogaster is one of the most widely used genetic models for studying development and disease. Here we combined quantitative proteomics with genetic selection to determine changes in the proteome upon depletion of Heartless (Htl) Fibroblast-Growth Factor (FGF) receptor signalling in Drosophila embryos at the gastrula stage. We present a robust, single generation SILAC (stable isotope labelling with amino acids in cell culture) protocol for labelling proteins in early embryos. For the selection of homozygously mutant embryos at the pre-gastrula stage, we developed an independent genetic marker. Our analyses detected quantitative changes in the global proteome of htl mutant embryos during gastrulation. We identified distinct classes of downregulated and upregulated proteins, and network analyses indicate functionally related groups of proteins in each class. In addition, we identified changes in the abundance of phosphopeptides. In summary, our quantitative proteomic analysis reveals global changes in metabolic, nucleoplasmic, cytoskeletal and transport proteins in htl mutant embryos.
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Affiliation(s)
- Hamze Beati
- Developmental Genetics Unit, Institute of Biology, University of Kassel , Kassel, Germany.,Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee , Dundee, UK
| | - Alistair Langlands
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee , Dundee, UK
| | - Sara Ten Have
- Division of Gene Regulation and Expression, School of Life Sciences, University of Dundee , Dundee, UK
| | - H-Arno J Müller
- Developmental Genetics Unit, Institute of Biology, University of Kassel , Kassel, Germany.,Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee , Dundee, UK
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Gao Y, Mao Y, Xu RG, Zhu R, Zhang M, Sun J, Shen D, Peng P, Xie T, Ni JQ. Defining gene networks controlling the maintenance and function of the differentiation niche by an in vivo systematic RNAi screen. J Genet Genomics 2019; 46:19-30. [PMID: 30745214 DOI: 10.1016/j.jgg.2018.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/02/2018] [Accepted: 10/23/2018] [Indexed: 01/13/2023]
Abstract
In the Drosophila ovary, escort cells (ECs) extrinsically control germline stem cell (GSC) maintenance and progeny differentiation. However, the underlying mechanisms remain poorly understood. In this study, we identified 173 EC genes for their roles in controlling GSC maintenance and progeny differentiation by using an in vivo systematic RNAi approach. Of the identified genes, 10 and 163 are required in ECs to promote GSC maintenance and progeny differentiation, respectively. The genes required for progeny differentiation fall into different functional categories, including transcription, mRNA splicing, protein degradation, signal transduction and cytoskeleton regulation. In addition, the GSC progeny differentiation defects caused by defective ECs are often associated with BMP signaling elevation, indicating that preventing BMP signaling is a general functional feature of the differentiation niche. Lastly, exon junction complex (EJC) components, which are essential for mRNA splicing, are required in ECs to promote GSC progeny differentiation by maintaining ECs and preventing BMP signaling. Therefore, this study has identified the major regulators of the differentiation niche, which provides important insights into how stem cell progeny differentiation is extrinsically controlled.
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Affiliation(s)
- Yuan Gao
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Ying Mao
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Rong-Gang Xu
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China; Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Ruibao Zhu
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China; Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Ming Zhang
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Jin Sun
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China; Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Da Shen
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China; Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Ping Peng
- PKU-THU Joint Center for Life Sciences, College of Life Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China; Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Ting Xie
- Stowers Institute for Medical Research, 1000 East 50(th) Street, Kansas City, MO, 64110, USA.
| | - Jian-Quan Ni
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China; Tsingdao Advanced Research Institute, Tongji University, Qingdao, 266000, China.
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Mason FM, Xie S, Vasquez CG, Tworoger M, Martin AC. RhoA GTPase inhibition organizes contraction during epithelial morphogenesis. J Cell Biol 2016; 214:603-17. [PMID: 27551058 PMCID: PMC5004446 DOI: 10.1083/jcb.201603077] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 07/15/2016] [Indexed: 12/05/2022] Open
Abstract
Mason et al. show that RhoA activity is regulated in space and time by a GEF/GAP module that tunes cell behavior and is required for proper tissue folding and shape during Drosophila morphogenesis. During morphogenesis, contraction of the actomyosin cytoskeleton within individual cells drives cell shape changes that fold tissues. Coordination of cytoskeletal contractility is mediated by regulating RhoA GTPase activity. Guanine nucleotide exchange factors (GEFs) activate and GTPase-activating proteins (GAPs) inhibit RhoA activity. Most studies of tissue folding, including apical constriction, have focused on how RhoA is activated by GEFs to promote cell contractility, with little investigation as to how GAPs may be important. Here, we identify a critical role for a RhoA GAP, Cumberland GAP (C-GAP), which coordinates with a RhoA GEF, RhoGEF2, to organize spatiotemporal contractility during Drosophila melanogaster apical constriction. C-GAP spatially restricts RhoA pathway activity to a central position in the apical cortex. RhoGEF2 pulses precede myosin, and C-GAP is required for pulsation, suggesting that contractile pulses result from RhoA activity cycling. Finally, C-GAP expression level influences the transition from reversible to irreversible cell shape change, which defines the onset of tissue shape change. Our data demonstrate that RhoA activity cycling and modulating the ratio of RhoGEF2 to C-GAP are required for tissue folding.
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Affiliation(s)
- Frank M Mason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Shicong Xie
- Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Claudia G Vasquez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Michael Tworoger
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
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Wernike D, Chen Y, Mastronardi K, Makil N, Piekny A. Mechanical forces drive neuroblast morphogenesis and are required for epidermal closure. Dev Biol 2016; 412:261-77. [PMID: 26923492 DOI: 10.1016/j.ydbio.2016.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/24/2016] [Accepted: 02/24/2016] [Indexed: 10/22/2022]
Abstract
Tissue morphogenesis requires myosin-dependent events such as cell shape changes and migration to be coordinated between cells within a tissue, and/or with cells from other tissues. However, few studies have investigated the simultaneous morphogenesis of multiple tissues in vivo. We found that during Caenorhabditis elegans ventral enclosure, when epidermal cells collectively migrate to cover the ventral surface of the embryo, the underlying neuroblasts (neuronal precursor cells) also undergo morphogenesis. We found that myosin accumulates as foci along the junction-free edges of the ventral epidermal cells to form a ring, whose closure is myosin-dependent. We also observed the accumulation of myosin foci and the adhesion junction proteins E-cadherin and α-catenin in the underlying neuroblasts. Myosin may help to reorganize a subset of neuroblasts into a rosette-like pattern, and decrease their surface area as the overlying epidermal cells constrict. Since myosin is required in the neuroblasts for ventral enclosure, we propose that mechanical forces in the neuroblasts influence constriction of the overlying epidermal cells. In support of this model, disrupting neuroblast cell division or altering their fate influences myosin localization in the overlying epidermal cells. The coordination of myosin-dependent events and forces between cells in different tissues could be a common theme for coordinating morphogenetic events during metazoan development.
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Affiliation(s)
- Denise Wernike
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Yun Chen
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | | | - Neetha Makil
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, Quebec, Canada.
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12
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Lebreton G, Casanova J. Ligand-binding and constitutive FGF receptors in single Drosophila tracheal cells: Implications for the role of FGF in collective migration. Dev Dyn 2015; 245:372-8. [PMID: 26342211 DOI: 10.1002/dvdy.24345] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 09/01/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The migration of individual cells relies on their capacity to evaluate differences across their bodies and to move either toward or against a chemoattractant or a chemorepellent signal respectively. However, the direction of collective migration is believed to depend on the internal organization of the cell cluster while the role of the external signal is limited to single out some cells in the cluster, conferring them with motility properties. RESULTS Here we analyzed the role of Fibroblast Growth Factor (FGF) signaling in collective migration in the Drosophila trachea. While ligand-binding FGF receptor (FGFR) activity in a single cell can drive migration of a tracheal cluster, we show that activity from a constitutively activated FGFR cannot-an observation that contrasts with previously analyzed cases. CONCLUSIONS Our results indicate that individual cells in the tracheal cluster can "read" differences in the distribution of FGFR activity and lead migration of the cluster accordingly. Thus, FGF can act as a chemoattractant rather than as a motogen in collective cell migration. This finding has many implications in both development and pathology.
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Affiliation(s)
- Gaëlle Lebreton
- Institut de Biologia Molecular de Barcelona (CSIC) and Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Catalonia, Spain
| | - Jordi Casanova
- Institut de Biologia Molecular de Barcelona (CSIC) and Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Catalonia, Spain
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14
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Mulinari S, Häcker U. Rho-guanine nucleotide exchange factors during development: Force is nothing without control. Small GTPases 2014; 1:28-43. [PMID: 21686118 DOI: 10.4161/sgtp.1.1.12672] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 05/31/2010] [Accepted: 06/14/2010] [Indexed: 01/04/2023] Open
Abstract
The development of multicellular organisms is associated with extensive rearrangements of tissues and cell sheets. The driving force for these rearrangements is generated mostly by the actin cytoskeleton. In order to permit the reproducible development of a specific body plan, dynamic reorganization of the actin cytoskeleton must be precisely coordinated in space and time. GTP-exchange factors that activate small GTPases of the Rho family play an important role in this process. Here we review the role of this class of cytoskeletal regulators during important developmental processes such as epithelial morphogenesis, cytokinesis, cell migration, cell polarity, neuronal growth cone extension and phagocytosis in different model systems.
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Affiliation(s)
- Shai Mulinari
- Department of Experimental Medical Science; Lund Strategic Research Center for Stem Cell Biology and Cell Therapy; Lund University; Lund, Sweden
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15
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Bustelo XR. A transcriptional cross-talk between RhoA and c-Myc inhibits the RhoA/Rock-dependent cytoskeleton. Small GTPases 2014; 1:69-74. [PMID: 21686122 DOI: 10.4161/sgtp.1.1.12986] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/12/2010] [Accepted: 07/13/2010] [Indexed: 01/09/2023] Open
Abstract
The GTPase RhoA and the transcriptional factor c-Myc are closely intertwined in cancer cells. Although this cross-talk results in potent synergistic effects that favor the transformed phenotype of cancer cells, recent results from our laboratory indicate that c-Myc also participates in a negative feed-back loop that blocks specific RhoA signaling branches connected to the induction of stress fibers, focal adhesions and actomyosin contractility. Using microarray analysis, we have unveiled a RhoA/c-Myc-dependent gene signature in charge of this negative cross-talk. This signature is composed of upregulated and repressed transcripts encoding cytoskeletal modulators located downstream of both RhoA and Rock. Our results also indicate that this negative feed-back loop modifies the invasion and adhesion properties of RhoA-transformed cells, suggesting that it may be important to ensure fluid cytoskeletal dynamics of cancer cells. Preliminary data indicate that c-Myc may also use a different transcriptional program to interfere with the RhoA/Rock-dependent cytoskeletal branch in non-transformed cells.
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Affiliation(s)
- Xosé R Bustelo
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer; CSIC-University of Salamanca; Campus Unamuno; Salamanca, Spain
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Su KC, Bement WM, Petronczki M, von Dassow G. An astral simulacrum of the central spindle accounts for normal, spindle-less, and anucleate cytokinesis in echinoderm embryos. Mol Biol Cell 2014; 25:4049-62. [PMID: 25298401 PMCID: PMC4263448 DOI: 10.1091/mbc.e14-04-0859] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Live imaging of Ect2 and Cyk4 in echinoderm embryos shows successive recruitment to central spindle, astral microtubules, and the cleavage furrow not only in normal cells, but also between paired asters in toroidal or anucleate cells. This suggests that a common signaling ensemble underlies all functional cytokinetic furrow induction events. Cytokinesis in animal cells depends on spindle-derived spatial cues that culminate in Rho activation, and thereby actomyosin assembly, in a narrow equatorial band. Although the nature, origin, and variety of such cues have long been obscure, one component is certainly the Rho activator Ect2. Here we describe the behavior and function of Ect2 in echinoderm embryos, showing that Ect2 migrates from spindle midzone to astral microtubules in anaphase and that Ect2 shapes the pattern of Rho activation in incipient furrows. Our key finding is that Ect2 and its binding partner Cyk4 accumulate not only at normal furrows, but also at furrows that form in the absence of associated spindle, midzone, or chromosomes. In all these cases, the cell assembles essentially the same cytokinetic signaling ensemble—opposed astral microtubules decorated with Ect2 and Cyk4. We conclude that if multiple signals contribute to furrow induction in echinoderm embryos, they likely converge on the same signaling ensemble on an analogous cytoskeletal scaffold.
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Affiliation(s)
- Kuan-Chung Su
- Oregon Institute of Marine Biology, Charleston, OR 97420 Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms EN6 3LD, United Kingdom
| | - William M Bement
- Oregon Institute of Marine Biology, Charleston, OR 97420 Laboratory of Cell and Molecular Biology, University of Wisconsin, Madison, WI 53706
| | - Mark Petronczki
- Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms EN6 3LD, United Kingdom
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17
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Greer ER, Chao AT, Bejsovec A. Pebble/ECT2 RhoGEF negatively regulates the Wingless/Wnt signaling pathway. Development 2013; 140:4937-46. [PMID: 24198276 DOI: 10.1242/dev.101303] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Wingless (Wg)/Wnt signaling is essential for patterning invertebrate and vertebrate embryos, and inappropriate Wnt activity is associated with a variety of human cancers. Despite intensive study, Wnt pathway mechanisms are not fully understood. We have discovered a new mechanism for regulating the Wnt pathway: activity of a Rho guanine nucleotide exchange factor (GEF) encoded by pebble (pbl) in Drosophila and ECT2 in humans. This RhoGEF has an essential role in cytokinesis, but also plays an unexpected, conserved role in inhibiting Wg/Wnt activity. Loss and gain of pbl function in Drosophila embryos cause pattern defects that indicate altered Wg activity. Both Pbl and ECT2 repress Wg/Wnt target gene expression in cultured Drosophila and human cells. The GEF activity is required for Wnt regulation, whereas other protein domains important for cytokinesis are not. Unlike most negative regulators of Wnt activity, Pbl/ECT2 functions downstream of Armadillo (Arm)/beta-catenin stabilization. Our results indicate GTPase regulation at a novel point in Wg/Wnt signal transduction, and provide new insight into the categorization of ECT2 as a human proto-oncogene.
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18
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Abstract
Tyrosine phosphorylation plays a significant role in a wide range of cellular processes. The Drosophila genome encodes more than 20 receptor tyrosine kinases and extensive studies in the past 20 years have illustrated their diverse roles and complex signaling mechanisms. Although some receptor tyrosine kinases have highly specific functions, others strikingly are used in rather ubiquitous manners. Receptor tyrosine kinases regulate a broad expanse of processes, ranging from cell survival and proliferation to differentiation and patterning. Remarkably, different receptor tyrosine kinases share many of the same effectors and their hierarchical organization is retained in disparate biological contexts. In this comprehensive review, we summarize what is known regarding each receptor tyrosine kinase during Drosophila development. Astonishingly, very little is known for approximately half of all Drosophila receptor tyrosine kinases.
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Affiliation(s)
- Richelle Sopko
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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19
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Ettensohn CA. Encoding anatomy: Developmental gene regulatory networks and morphogenesis. Genesis 2013; 51:383-409. [PMID: 23436627 DOI: 10.1002/dvg.22380] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/06/2013] [Accepted: 02/07/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Charles A. Ettensohn
- Department of Biological Sciences; Carnegie Mellon University; Pittsburgh; Pennsylvania
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20
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Muha V, Müller HAJ. Functions and Mechanisms of Fibroblast Growth Factor (FGF) Signalling in Drosophila melanogaster. Int J Mol Sci 2013; 14:5920-37. [PMID: 23493057 PMCID: PMC3634451 DOI: 10.3390/ijms14035920] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 03/05/2013] [Accepted: 03/12/2013] [Indexed: 01/19/2023] Open
Abstract
Intercellular signalling via growth factors plays an important role in controlling cell differentiation and cell movements during the development of multicellular animals. Fibroblast Growth Factor (FGF) signalling induces changes in cellular behaviour allowing cells in the embryo to move, to survive, to divide or to differentiate. Several examples argue that FGF signalling is used in multi-step morphogenetic processes to achieve and maintain a transitional state of the cells required for the control of cell fate. In the genetic model Drosophila melanogaster, FGF signalling via the receptor tyrosine kinases Heartless (Htl) and Breathless (Btl) is particularly well studied. These FGF receptors affect gene expression, cell shape and cell–cell interactions during mesoderm layer formation, caudal visceral muscle (CVM) formation, tracheal morphogenesis and glia differentiation. Here, we will address the current knowledge of the biological functions of FGF signalling in the fly on the tissue, at a cellular and molecular level.
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Affiliation(s)
- Villö Muha
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD15EH, Scotland, UK.
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21
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Nakamura M, Matsumoto K, Iwamoto Y, Muguruma T, Nakazawa N, Hatori R, Taniguchi K, Maeda R, Matsuno K. Reduced cell number in the hindgut epithelium disrupts hindgut left–right asymmetry in a mutant of pebble, encoding a RhoGEF, in Drosophila embryos. Mech Dev 2013; 130:169-80. [DOI: 10.1016/j.mod.2012.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 09/24/2012] [Accepted: 09/26/2012] [Indexed: 10/27/2022]
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22
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White EA, Glotzer M. Centralspindlin: at the heart of cytokinesis. Cytoskeleton (Hoboken) 2012; 69:882-92. [PMID: 22927365 PMCID: PMC3821549 DOI: 10.1002/cm.21065] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/15/2012] [Accepted: 08/20/2012] [Indexed: 12/14/2022]
Abstract
The final step in the cell cycle is the formation of two genetically identical daughter cells by cytokinesis. At the heart of cytokinesis in animal cells is the centralspindlin complex which is composed of two proteins, a kinesin-like protein, Mitotic kinesin-like protein 1, and a Rho GTPase activating protein (RhoGAP), CYK-4. Through its targeted localization to a narrow region of antiparallel microtubule overlap immediately following chromosome segregation, centralspindlin initiates central spindle assembly. Centralspindlin has several critical functions during cell division including positioning of the division plane, regulation of Rho family GTPases, as well as midbody assembly and abscission. In this review, we will examine the biochemistry of centralspindlin and its multiple functions during cell division. Remarkably, several of its critical functions are somewhat unexpected. Although endowed with motor domains, centralspindlin has an important role in generating stable, antiparallel microtubule bundles. Although it contains a Rho family GAP domain, it has a central role in the activation of RhoA during cytokinesis. Finally, centralspindlin functions as a motor protein complex, as a scaffold protein for key regulators of abscission and as a conventional RhoGAP. Because of these diverse functions, centralspindlin lies at the heart of the cytokinetic mechanism.
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Affiliation(s)
- Erin A. White
- Department of Molecular Genetics and Cell Biology, University of
Chicago, CLSC 901, 920 E. 58th St. Chicago, IL 60637
| | - Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of
Chicago, CLSC 901, 920 E. 58th St. Chicago, IL 60637
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23
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Regulation of Drosophila mesoderm migration by phosphoinositides and the PH domain of the Rho GTP exchange factor Pebble. Dev Biol 2012; 372:17-27. [PMID: 23000359 DOI: 10.1016/j.ydbio.2012.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 08/20/2012] [Accepted: 09/13/2012] [Indexed: 11/27/2022]
Abstract
The Drosophila RhoGEF Pebble (Pbl) is required for cytokinesis and migration of mesodermal cells. In a screen for genes that could suppress migration defects in pbl mutants we identified the phosphatidylinositol phosphate (PtdInsP) regulator pi5k59B. Genetic interaction tests with other PtdInsP regulators suggested that PtdIns(4,5)P2 levels are important for mesoderm migration when Pbl is depleted. Consistent with this, the leading front of migrating mesodermal cells was enriched for PtdIns(4,5)P2. Given that Pbl contains a Pleckstrin Homology (PH) domain, a known PtdInsP-binding motif, we examined PtdInsP-binding of Pbl and the importance of the PH domain for Pbl function. In vitro lipid blot assays showed that Pbl binds promiscuously to PtdInsPs, with binding strength associated with the degree of phosphorylation. Pbl was also able to bind lipid vesicles containing PtdIns(4,5)P2 but binding was strongly reduced upon deletion of the PH domain. Similarly, in vivo, loss of the PH domain prevented localisation of Pbl to the cell cortex and severely affected several aspects of early mesoderm development, including flattening of the invaginated tube onto the ectoderm, extension of protrusions, and dorsal migration to form a monolayer. Pbl lacking the PH domain could still localise to the cytokinetic furrow, however, and cytokinesis failure was reduced in pbl(ΔPH) mutants. Taken together, our results support a model in which interaction of the PH-domain of Pbl with PtdIns(4,5)P2 helps localise it to the plasma membrane which is important for mesoderm migration.
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24
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Snail-dependent repression of the RhoGEF pebble is required for gastrulation consistency in Drosophila melanogaster. Dev Genes Evol 2012; 222:361-8. [PMID: 22945369 PMCID: PMC3644191 DOI: 10.1007/s00427-012-0414-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 08/16/2012] [Indexed: 11/14/2022]
Abstract
The Rho GTP exchange factor, Pebble (Pbl), long recognised as an essential activator of Rho during cytokinesis, also regulates mesoderm migration at gastrulation. Like other cell cycle components, pbl expression patterns broadly correlate with proliferative tissue. Surprisingly, in spite of its role in the early mesoderm, pbl is downregulated in the presumptive mesoderm before ventral furrow formation. Here, we show that this mesoderm-specific repression of pbl is dependent on the transcriptional repressor Snail (Sna). pbl repression was lost in sna mutants but was unaffected when Sna was ectopically expressed, showing that Sna is necessary, but not sufficient, for pbl repression. Using DamID, the first intron of pbl was identified as a Sna-binding region. Nine sites with the Sna-binding consensus motif CAGGT[GA] were identified in this intron. Mutating these to TAGGC[GA] abolished the ventral repression of pbl. Surprisingly, Sna-dependent repression of pbl was not essential for viability or fertility. Loss of repression did, however, increase the frequency of low-penetrance gastrulation defects. Consistent with this, expression of a pbl-GFP transgene in the presumptive mesoderm generated similar gastrulation defects. Finally, we show that a cluster of Snail-binding sites in the middle of the first intron of pbl orthologues is a conserved feature in the other 11 sequenced Drosophila species. We conclude that pbl levels are precisely regulated to ensure that there is enough protein available for its role in early mesoderm development but not so much as to inhibit the orderly progression of gastrulation.
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25
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Menant A, Karess RE. Inducing "cytokinesis" without mitosis in unfertilized Drosophila eggs. Cell Cycle 2012; 11:2856-63. [PMID: 22801541 DOI: 10.4161/cc.21190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Selection of the cleavage plane during cytokinesis in dividing cells is linked to the position of the mitotic spindle. A major player in cleavage plane positioning is believed to be the anaphase central spindle and its associated signaling complex called centralspindlin, composed of MgcRacGap and MKLP1. Centralspindlin has the capacity to induce furrowing of the cell cortex by promoting the localized activation of RhoA, which in turn promotes assembly of the contractile ring. We have found a way to induce a cytokinesis-like process in unfertilized Drosophila eggs and very early embryos, when spindle structures are few and located far from invaginating egg cortex. The simple injection of a small molecule inhibitor of Cdk1/Cyclin B (either Roscovitin or RO3306) is sufficient to promote membrane invagination near the site of injection. The furrow generated is in many respects similar to a classical cleavage furrow. Actin, myosin, anillin and MKLP1 are all associated with the forming furrow, which in some cases can entirely circumscribe the unfertilized egg. A similar furrow can also be generated by the localized injection of constitutively active RhoA protein, suggesting that Cdk1 is normally an upstream inhibitor of RhoA activation. We show further that this process apparently is not associated with microtubules. Since simple localized inhibition of Cdk1 is sufficient to induce a furrow, we suggest that in real cytokinesis in normal cells, the localized downregulation of Cdk1 activity at the metaphase-anaphase transition may contribute, along with the spindle, to the positioning of the cleavage furrow.
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Affiliation(s)
- Alexandra Menant
- CNRS, Institut Jacques Monod, UMR7592, Université Paris Diderot, Paris, France
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26
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Reim I, Hollfelder D, Ismat A, Frasch M. The FGF8-related signals Pyramus and Thisbe promote pathfinding, substrate adhesion, and survival of migrating longitudinal gut muscle founder cells. Dev Biol 2012; 368:28-43. [PMID: 22609944 DOI: 10.1016/j.ydbio.2012.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 04/17/2012] [Accepted: 05/04/2012] [Indexed: 01/04/2023]
Abstract
Fibroblast growth factors (FGFs) frequently fulfill prominent roles in the regulation of cell migration in various contexts. In Drosophila, the FGF8-like ligands Pyramus (Pyr) and Thisbe (Ths), which signal through their receptor Heartless (Htl), are known to regulate early mesodermal cell migration after gastrulation as well as glial cell migration during eye development. Herein, we show that Pyr and Ths also exert key roles during the long-distance migration of a specific sub-population of mesodermal cells that migrate from the caudal visceral mesoderm within stereotypic bilateral paths along the trunk visceral mesoderm toward the anterior. These cells constitute the founder myoblasts of the longitudinal midgut muscles. In a forward genetic screen for regulators of this morphogenetic process we identified loss of function alleles for pyr. We show that pyr and ths are expressed along the paths of migration in the trunk visceral mesoderm and endoderm and act largely redundantly to help guide the founder myoblasts reliably onto and along their substrate of migration. Ectopically-provided Pyr and Ths signals can efficiently re-rout the migrating cells, both in the presence and absence of endogenous signals. Our data indicate that the guidance functions of these FGFs must act in concert with other important attractive or adhesive activities of the trunk visceral mesoderm. Apart from their guidance functions, the Pyr and Ths signals play an obligatory role for the survival of the migrating cells. Without these signals, essentially all of these cells enter cell death and detach from the migration substrate during early migration. We present experiments that allowed us to dissect the roles of these FGFs as guidance cues versus trophic activities during the migration of the longitudinal visceral muscle founders.
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Affiliation(s)
- Ingolf Reim
- University of Erlangen-Nuremberg, Department of Biology, Division of Developmental Biology, Staudtstr. 5, 91058 Erlangen, Germany
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27
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Mariappa D, Sauert K, Mariño K, Turnock D, Webster R, van Aalten DMF, Ferguson MAJ, Müller HAJ. Protein O-GlcNAcylation is required for fibroblast growth factor signaling in Drosophila. Sci Signal 2011; 4:ra89. [PMID: 22375049 DOI: 10.1126/scisignal.2002335] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Glycosylation is essential for growth factor signaling through N-glycosylation of ligands and receptors and the biosynthesis of proteoglycans as co-receptors. Here, we show that protein O-GlcNAcylation is crucial for fibroblast growth factor (FGF) signaling in Drosophila. We found that nesthocker (nst) encodes a phosphoacetylglucosamine mutase and that nst mutant embryos exhibited low amounts of intracellular uridine 5'-diphosphate-N-acetylglucosamine (UDP-GlcNAc), which disrupted protein O-GlcNAcylation. Nst was required for mitogen-activated protein kinase (MAPK) signaling downstream of FGF but not MAPK signaling activated by epidermal growth factor. nst was dispensable for the function of the FGF ligands and the FGF receptor's extracellular domain but was essential in the signal-receiving cells downstream of the FGF receptor. We identified the adaptor protein Downstream of FGF receptor (Dof), which interacts with the FGF receptor, as the relevant target for O-GlcNAcylation in the FGF pathway, suggesting that protein O-GlcNAcylation of the activated receptor complex is essential for FGF signal transduction.
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Affiliation(s)
- Daniel Mariappa
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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28
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Cook DR, Solski PA, Bultman SJ, Kauselmann G, Schoor M, Kuehn R, Friedman LS, Cowley DO, Van Dyke T, Yeh JJ, Johnson L, Der CJ. The ect2 rho Guanine nucleotide exchange factor is essential for early mouse development and normal cell cytokinesis and migration. Genes Cancer 2011; 2:932-42. [PMID: 22701760 PMCID: PMC3374631 DOI: 10.1177/1947601912437035] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/14/2011] [Accepted: 12/18/2011] [Indexed: 12/23/2022] Open
Abstract
Ect2 is a member of the human Dbl family of guanine nucleotide exchange factors (RhoGEFs) that serve as activators of Rho family small GTPases. Although Ect2 is one of at least 25 RhoGEFs that can activate the RhoA small GTPase, cell culture studies using established cell lines determined that Ect2 is essential for mammalian cell cytokinesis and proliferation. To address the function of Ect2 in normal mammalian development, we performed gene targeting to generate Ect2 knockout mice. The heterozygous Ect2(+/-) mice showed normal development and life span, indicating that Ect2 haplodeficiency was not deleterious for development or growth. In contrast, Ect2(-/-) embryos were not found at birth or postimplantation stages. Ect2(-/-) blastocysts were recovered at embryonic day 3.5 but did not give rise to viable outgrowths in culture, indicating that Ect2 is required for peri-implantation development. To further assess the importance of Ect2 in normal cell physiology, we isolated primary fibroblasts from Ect2(fl/fl) embryos (MEFs) and ablated Ect2 using adenoviral delivery of Cre recombinase. We observed a significant increase in multinucleated cells and accumulation of cells in G2/M phase, consistent with a role for Ect2 in cytokinesis. Ect2 deficiency also caused enlargement of the cytoplasm and impaired cell migration. Finally, although Ect2-dependent activation of RhoA has been implicated in cytokinesis, Ect2 can also activate Rac1 and Cdc42 to cause growth transformation. Surprisingly, ectopic expression of constitutively activated RhoA, Rac1, or Cdc42, known substrates of Ect2, failed to phenocopy Ect2 and did not rescue the defect in cytokinesis caused by loss of Ect2. In summary, our results establish the unique role of Ect2 in development and normal cell proliferation.
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Affiliation(s)
- Danielle R. Cook
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Patricia A. Solski
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Scott J. Bultman
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | | | - Ralf Kuehn
- TaconicArtemis GmbH, Cologne, Germany
- Institute of Developmental Genetics, Helmholtz Center Munich, Munich, Germany
- Institute of Developmental Genetics, Helmholtz Center Munich, Munich,Germany
| | - Lori S. Friedman
- Exelixis Inc., South San Francisco, CA, USA
- Genentech Inc., South San Francisco, CA, USA
| | - Dale O. Cowley
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Terry Van Dyke
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jen Jen Yeh
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Leisa Johnson
- Exelixis Inc., South San Francisco, CA, USA
- Genentech Inc., South San Francisco, CA, USA
| | - Channing J. Der
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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29
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Abstract
During gastrulation, the mesoderm spreads out between ectoderm and endoderm to form a mesenchymal cell layer. Surprisingly the underlying principles of mesoderm layer formation are very similar in evolutionarily distant species like the fruit fly, Drosophila melanogaster, and the frog, Xenopus laevis, in which the molecular and the cellular basis of mesoderm layer formation have been extensively studied. Complementary expression of growth factors in the ectoderm and their receptors in the mesoderm act to orient cellular protrusive activities and direct cell movement, leading to radial cell intercalation and the spreading of the mesoderm layer. This mechanism is contrasted with generic physical mechanisms of tissue spreading that consider the adhesive and physical properties of the cells and tissues. Both mechanisms need to be integrated to orchestrate mesenchymal morphogenesis.
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Affiliation(s)
- Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
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30
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Jankovics F, Henn L, Bujna Á, Vilmos P, Kiss N, Erdélyi M. A functional genomic screen combined with time-lapse microscopy uncovers a novel set of genes involved in dorsal closure of Drosophila embryos. PLoS One 2011; 6:e22229. [PMID: 21799798 PMCID: PMC3140500 DOI: 10.1371/journal.pone.0022229] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 06/17/2011] [Indexed: 11/19/2022] Open
Abstract
Morphogenesis, the establishment of the animal body, requires the coordinated rearrangement of cells and tissues regulated by a very strictly-determined genetic program. Dorsal closure of the epithelium in the Drosophila melanogaster embryo is one of the best models for such a complex morphogenetic event. To explore the genetic regulation of dorsal closure, we carried out a large-scale RNA interference-based screen in combination with in vivo time-lapse microscopy and identified several genes essential for the closure or affecting its dynamics. One of the novel dorsal closure genes, the small GTPase activator pebble (pbl), was selected for detailed analysis. We show that pbl regulates actin accumulation and protrusion dynamics in the leading edge of the migrating epithelial cells. In addition, pbl affects dorsal closure dynamics by regulating head involution, a morphogenetic process mechanically coupled with dorsal closure. Finally, we provide evidence that pbl is involved in closure of the adult thorax, suggesting its general requirement in epithelial closure processes.
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Affiliation(s)
- Ferenc Jankovics
- Institute of Genetics, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary.
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31
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Clark IBN, Muha V, Klingseisen A, Leptin M, Müller HAJ. Fibroblast growth factor signalling controls successive cell behaviours during mesoderm layer formation in Drosophila. Development 2011; 138:2705-15. [PMID: 21613323 DOI: 10.1242/dev.060277] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Fibroblast growth factor (FGF)-dependent epithelial-mesenchymal transitions and cell migration contribute to the establishment of germ layers in vertebrates and other animals, but a comprehensive demonstration of the cellular activities that FGF controls to mediate these events has not been provided for any system. The establishment of the Drosophila mesoderm layer from an epithelial primordium involves a transition to a mesenchymal state and the dispersal of cells away from the site of internalisation in a FGF-dependent fashion. We show here that FGF plays multiple roles at successive stages of mesoderm morphogenesis in Drosophila. It is first required for the mesoderm primordium to lose its epithelial polarity. An intimate, FGF-dependent contact is established and maintained between the germ layers through mesoderm cell protrusions. These protrusions extend deep into the underlying ectoderm epithelium and are associated with high levels of E-cadherin at the germ layer interface. Finally, FGF directs distinct hitherto unrecognised and partially redundant protrusive behaviours during later mesoderm spreading. Cells first move radially towards the ectoderm, and then switch to a dorsally directed movement across its surface. We show that both movements are important for layer formation and present evidence suggesting that they are controlled by genetically distinct mechanisms.
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Affiliation(s)
- Ivan B N Clark
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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32
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Vlachos S, Harden N. Genetic evidence for antagonism between Pak protein kinase and Rho1 small GTPase signaling in regulation of the actin cytoskeleton during Drosophila oogenesis. Genetics 2011; 187:501-12. [PMID: 21098722 PMCID: PMC3030492 DOI: 10.1534/genetics.110.120998] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 11/18/2010] [Indexed: 12/15/2022] Open
Abstract
During Drosophila oogenesis, basally localized F-actin bundles in the follicle cells covering the egg chamber drive its elongation along the anterior-posterior axis. The basal F-actin of the follicle cell is an attractive system for the genetic analysis of the regulation of the actin cytoskeleton, and results obtained in this system are likely to be broadly applicable in understanding tissue remodeling. Mutations in a number of genes, including that encoding the p21-activated kinase Pak, have been shown to disrupt organization of the basal F-actin and in turn affect egg chamber elongation. pak mutant egg chambers have disorganized F-actin distribution and remain spherical due to a failure to elongate. In a genetic screen to identify modifiers of the pak rounded egg chamber phenotype several second chromosome deficiencies were identified as suppressors. One suppressing deficiency removes the rho1 locus, and we determined using several rho1 alleles that removal of a single copy of rho1 can suppress the pak phenotype. Reduction of any component of the Rho1-activated actomyosin contractility pathway suppresses pak oogenesis defects, suggesting that Pak counteracts Rho1 signaling. There is ectopic myosin light chain phosphorylation in pak mutant follicle cell clones in elongating egg chambers, probably due at least in part to mislocalization of RhoGEF2, an activator of the Rho1 pathway. In early egg chambers, pak mutant follicle cells have reduced levels of myosin phosphorylation and we conclude that Pak both promotes and restricts myosin light chain phosphorylation in a temporally distinct manner during oogenesis.
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Affiliation(s)
| | - Nicholas Harden
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
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33
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Kedinger V, Nepveu A. The roles of CUX1 homeodomain proteins in the establishment of a transcriptional program required for cell migration and invasion. Cell Adh Migr 2010; 4:348-52. [PMID: 20224295 DOI: 10.4161/cam.4.3.11407] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The Cut homeobox gene 1 (CUX1) codes for several homeodomain proteins that display distinct DNA binding and transcriptional properties. Some CUX1 isoforms were previously shown to stimulate entry into S phase. More recently, siRNA-mediated knockdown of CUX1 was shown to cause a decrease in cell migration and invasion. In contrast, ectopic expression of p110 or p75 CUX1 stimulated cell migration and invasion in tissue culture. Moreover, metastasis to the lung was observed in a few cases following development of mammary tumors in p75 CUX1 transgenic mice. Chromatin immunoprecipitation (ChIP) assays followed by hybridization on promoter arrays (ChIP-chip) led to the identification of more than 20 genes that are directly regulated by CUX1 and code for proteins involved in cytoskeleton remodeling, cell-cell and cell-matrix adhesion, epithelial to mesenchymal transition and transcriptional regulation. Many targets of CUX1 are regulators of Rho GTPases that play a role both in cell cycle progression and cell motility. Interestingly, some genes that promote cell motility are activated by CUX1, while some genes that inhibit cell motility are repressed by CUX1. The dual function of CUX1 as an activator and repressor is best exemplified by the regulatory cascade whereby CUX1 activates expression of the Snail and Slug transcription factors and then cooperates with them to repress the E-cadherin and occludin genes, thereby causing a severe disorganization of cell-cell junctions. Together, these studies indicate that CUX1 stimulates cell motility by regulating a large number of genes involved in various molecular functions.
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McMahon A, Reeves GT, Supatto W, Stathopoulos A. Mesoderm migration in Drosophila is a multi-step process requiring FGF signaling and integrin activity. Development 2010; 137:2167-75. [PMID: 20530544 DOI: 10.1242/dev.051573] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Migration is a complex, dynamic process that has largely been studied using qualitative or static approaches. As technology has improved, we can now take quantitative approaches towards understanding cell migration using in vivo imaging and tracking analyses. In this manner, we have established a four-step model of mesoderm migration during Drosophila gastrulation: (I) mesodermal tube formation, (II) collapse of the mesoderm, (III) dorsal migration and spreading and (IV) monolayer formation. Our data provide evidence that these steps are temporally distinct and that each might require different chemical inputs. To support this, we analyzed the role of fibroblast growth factor (FGF) signaling, in particular the function of two Drosophila FGF ligands, Pyramus and Thisbe, during mesoderm migration. We determined that FGF signaling through both ligands controls movements in the radial direction. Thisbe is required for the initial collapse of the mesoderm onto the ectoderm, whereas both Pyramus and Thisbe are required for monolayer formation. In addition, we uncovered that the GTPase Rap1 regulates radial movement of cells and localization of the beta-integrin subunit, Myospheroid, which is also required for monolayer formation. Our analyses suggest that distinct signals influence particular movements, as we found that FGF signaling is involved in controlling collapse and monolayer formation but not dorsal movement, whereas integrins are required to support monolayer formation only and not earlier movements. Our work demonstrates that complex cell migration is not necessarily a fluid process, but suggests instead that different types of movements are directed by distinct inputs in a stepwise manner.
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Affiliation(s)
- Amy McMahon
- California Institute of Technology, Division of Biology MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
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35
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Gregory SL, Lorensuhewa N, Saint R. Signalling through the RhoGEF Pebble in Drosophila. IUBMB Life 2010; 62:290-5. [PMID: 20175154 DOI: 10.1002/iub.310] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Small GTPase pathways of the Ras superfamily are implicated in a wide range of signalling processes in animal cells. Small GTPases control pathways by acting as molecular switches. They are converted from an inactive GDP-bound form to an active GTP-bound form by GTP exchange factors (GEFs). The spatial and temporal regulation of GEFs is a major component of the regulation of small GTPases. Here we review the role of the Drosophila RhoGEF, Pebble (the Drosophila ortholog of mammalian ECT2). We discuss its roles in cytokinesis and cell migration, highlighting the diversity with which Rho family signalling pathways operate in biological systems.
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Affiliation(s)
- Stephen L Gregory
- School of Molecular and Biomedical Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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36
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Dynamic regulation of LARG in blastopore closure and archenteron formation during Xenopus laevis gastrulation. Genes Genomics 2010. [DOI: 10.1007/s13258-010-0861-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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37
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Klingseisen A, Clark IBN, Gryzik T, Müller HAJ. Differential and overlapping functions of two closely related Drosophila FGF8-like growth factors in mesoderm development. Development 2009; 136:2393-402. [PMID: 19515694 DOI: 10.1242/dev.035451] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Thisbe (Ths) and Pyramus (Pyr), two closely related Drosophila homologues of the vertebrate fibroblast growth factor (FGF) 8/17/18 subfamily, are ligands for the FGF receptor Heartless (Htl). Both ligands are required for mesoderm development, but their differential expression patterns suggest distinct functions during development. We generated single mutants and found that ths or pyr loss-of-function mutations are semi-lethal and mutants exhibit much weaker phenotypes as compared with loss of both ligands or htl. Thus, pyr and ths display partial redundancy in their requirement in embryogenesis and viability. Nevertheless, we find that pyr and ths single mutants display defects in gastrulation and mesoderm differentiation. We show that localised expression of pyr is required for normal cell protrusions and high levels of MAPK activation in migrating mesoderm cells. The results support the model that Pyr acts as an instructive cue for mesoderm migration during gastrulation. Consistent with this function, mutations in pyr affect the normal segmental number of cardioblasts. Furthermore, Pyr is essential for the specification of even-skipped-positive mesodermal precursors and Pyr and Ths are both required for the specification of a subset of somatic muscles. The results demonstrate both independent and overlapping functions of two FGF8 homologues in mesoderm morphogenesis and differentiation. We propose that the integration of Pyr and Ths function is required for robustness of Htl-dependent mesoderm spreading and differentiation, but that the functions of Pyr have become more specific, possibly representing an early stage of functional divergence after gene duplication of a common ancestor.
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Affiliation(s)
- Anna Klingseisen
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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38
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van Impel A, Schumacher S, Draga M, Herz HM, Grosshans J, Müller HAJ. Regulation of the Rac GTPase pathway by the multifunctional Rho GEF Pebble is essential for mesoderm migration in the Drosophila gastrula. Development 2009; 136:813-22. [PMID: 19176590 PMCID: PMC2685947 DOI: 10.1242/dev.026203] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2009] [Indexed: 01/09/2023]
Abstract
The Drosophila guanine nucleotide exchange factor Pebble (Pbl) is essential for cytokinesis and cell migration during gastrulation. In dividing cells, Pbl promotes Rho1 activation at the cell cortex, leading to formation of the contractile actin-myosin ring. The role of Pbl in fibroblast growth factor-triggered mesoderm spreading during gastrulation is less well understood and its targets and subcellular localization are unknown. To address these issues we performed a domain-function study in the embryo. We show that Pbl is localized to the nucleus and the cell cortex in migrating mesoderm cells and found that, in addition to the PH domain, the conserved C-terminal tail of the protein is crucial for cortical localization. Moreover, we show that the Rac pathway plays an essential role during mesoderm migration. Genetic and biochemical interactions indicate that during mesoderm migration, Pbl functions by activating a Rac-dependent pathway. Furthermore, gain-of-function and rescue experiments suggest an important regulatory role of the C-terminal tail of Pbl for the selective activation of Rho1-versus Rac-dependent pathways.
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Affiliation(s)
- Andreas van Impel
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, UK
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39
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Seguin L, Liot C, Mzali R, Harada R, Siret A, Nepveu A, Bertoglio J. CUX1 and E2F1 regulate coordinated expression of the mitotic complex genes Ect2, MgcRacGAP, and MKLP1 in S phase. Mol Cell Biol 2009; 29:570-81. [PMID: 19015243 PMCID: PMC2612504 DOI: 10.1128/mcb.01275-08] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/13/2008] [Accepted: 11/03/2008] [Indexed: 01/19/2023] Open
Abstract
Rho GTPases are critical for mitosis progression and completion of cytokinesis. During mitosis, the GDP/GTP cycle of Rho GTPases is regulated by the exchange factor Ect2 and the GTPase activating protein MgcRacGAP which associates with the kinesin MKLP1 in the centralspindlin complex. We report here that expression of Ect2, MgcRacGAP, and MKLP1 is tightly regulated during cell cycle progression. These three genes share similar cell cycle-related signatures within their promoter regions: (i) cell cycle gene homology region (CHR) sites located at -20 to +40 nucleotides of their transcription start sites that are required for repression in G(1), (ii) E2F binding elements, and (iii) tandem repeats of target sequences for the CUX1 transcription factor. CUX1 and E2F1 bind these three promoters upon S-phase entry, as demonstrated by chromatin immunoprecipitation, and regulate transcription of these genes, as established using promoter-luciferase reporter constructs and expression of activated or dominant negative transcription factors. Overexpression of either E2F1 or CUX1 increased the levels of the endogenous proteins whereas small interfering RNA knockdown of E2F1 or use of a dominant negative E2F1 reduced their expression levels. Thus, CUX1, E2F, and CHR elements provide the transcriptional controls that coordinate induction of Ect2, MgcRacGAP, and MKLP1 in S phase, leading to peak expression of these interacting proteins in G(2)/M, at the time they are required to regulate cytokinesis.
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Affiliation(s)
- Laetitia Seguin
- INSERM U749, Faculté de Pharmacie Paris XI, 92296 Châtenay-Malabry, France
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40
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McMahon A, Supatto W, Fraser SE, Stathopoulos A. Dynamic analyses of Drosophila gastrulation provide insights into collective cell migration. Science 2008; 322:1546-50. [PMID: 19056986 DOI: 10.1126/science.1167094] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The concerted movement of cells from different germ layers contributes to morphogenesis during early embryonic development. Using an optimized imaging approach and quantitative methods, we analyzed the trajectories of hundreds of ectodermal cells and internalized mesodermal cells within Drosophila embryos over 2 hours during gastrulation. We found a high level of cellular organization, with mesoderm cell movements correlating with some but not all ectoderm movements. During migration, the mesoderm population underwent two ordered waves of cell division and synchronous cell intercalation, and cells at the leading edge stably maintained position. Fibroblast growth factor (FGF) signaling guides mesodermal cell migration; however, we found some directed dorsal migration in an FGF receptor mutant, which suggests that additional signals are involved. Thus, decomposing complex cellular movements can provide detailed insights into collective cell migration.
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Affiliation(s)
- Amy McMahon
- Division of Biology, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
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41
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Fukai J, Yokote H, Yamanaka R, Arao T, Nishio K, Itakura T. EphA4 promotes cell proliferation and migration through a novel EphA4-FGFR1 signaling pathway in the human glioma U251 cell line. Mol Cancer Ther 2008; 7:2768-78. [PMID: 18790757 DOI: 10.1158/1535-7163.mct-07-2263] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Eph receptor tyrosine kinases and their ephrin ligands form a unique cell-cell contact-mediated bidirectional signaling mechanism for regulating cell localization and organization. High expression of Eph receptors in a wide variety of human tumors indicates some roles in tumor progression, which makes these proteins potential targets for anticancer therapy. For this purpose, we did gene expression profiling for 47 surgical specimens of brain tumors including 32 high-grade glioma using a microarray technique. The analysis, focused on the receptor tyrosine kinases, showed that EphA4 mRNA in the tumors was 4-fold higher than in normal brain tissue. To investigate the biological significance of EphA4 overexpression in these tumors, we analyzed EphA4-induced phenotypic changes and the signaling mechanisms using human glioma U251 cells. EphA4 promoted fibroblast growth factor 2-mediated cell proliferation and migration accompanied with enhancement of fibroblast growth factor 2-triggered mitogen-activated protein kinase and Akt phosphorylation. In addition, active forms of Rac1 and Cdc42 increased in the EphA4-overexpressing cells. Furthermore, we found that EphA4 formed a heteroreceptor complex with fibroblast growth factor receptor 1 (FGFR1) in the cells and that the EphA4-FGFR1 complex potentiated FGFR-mediated downstream signaling. Thus, our results indicate that EphA4 plays an important role in malignant phenotypes of glioblastoma by enhancing cell proliferation and migration through accelerating a canonical FGFR signaling pathway.
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Affiliation(s)
- Junya Fukai
- Department of Neurological Surgery, Wakayama Medical University, Wakayama, Japan
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42
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Baum B, Settleman J, Quinlan MP. Transitions between epithelial and mesenchymal states in development and disease. Semin Cell Dev Biol 2008; 19:294-308. [PMID: 18343170 DOI: 10.1016/j.semcdb.2008.02.001] [Citation(s) in RCA: 319] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Accepted: 02/04/2008] [Indexed: 12/21/2022]
Abstract
The ancestors of modern Metazoa were constructed in large part by the foldings and distortions of two-dimensional sheets of epithelial cells. This changed approximately 600 million years ago with the evolution of mesenchymal cells. These cells arise as the result of epithelial cell delamination through a reprogramming process called an epithelial to mesenchymal transition (EMT) [Shook D, Keller R. Mechanisms, mechanics and function of epithelial-mesenchymal transitions in early development. Mech Dev 2003;120:1351-83; Thiery JP, Sleeman JP. Complex networks orchestrate epithelial-mesenchymal transitions. Nat Rev Mol Cell Biol 2006;7:131-42]. Because mesenchymal cells are free to migrate through the body cavity, the evolution of the mesenchyme opened up new avenues for morphological plasticity, as cells evolved the ability to take up new positions within the embryo and to participate in novel cell-cell interactions; forming new types of internal tissues and organs such as muscle and bone [Thiery JP, Sleeman, JP. Complex networks orchestrate epithelial-mesenchymal transitions. Nat Rev Mol Cell Biol 2006;7:131-42; Hay ED, Zuk A. Transformations between epithelium and mesenchyme: normal, pathological, and experimentally induced. Am J Kidney Dis 1995;26:678-90]. After migrating to a suitable site, mesenchymal cells coalesce and re-polarize to form secondary epithelia, in a so-called mesenchymal-epithelial transition (MET). Such switches between mesenchymal and epithelial states are a frequent feature of Metazoan gastrulation [Hay ED, Zuk A. Transformations between epithelium and mesenchyme: normal, pathological, and experimentally induced. Am J Kidney Dis 1995;26:678-90] and the neural crest lineage [Duband JL, Monier F, Delannet M, Newgreen D. Epitheliu-mmesenchyme transition during neural crest development. Acta Anat 1995;154:63-78]. Significantly, however, when hijacked during the development of cancer, the ability of cells to undergo EMT, to leave the primary tumor and to undergo MET at secondary sites can have devastating consequences on the organism, allowing tumor cells derived from epithelia to invade surrounding tissues and spread through the host [Thiery JP, Sleeman JP. Complex networks orchestrate epithelial-mesenchymal transitions. Nat Rev Mol Cell Biol 2006;7:131-42; Hay ED, Zuk A. Transformations between epithelium and mesenchyme: normal, pathological, and experimentally induced. Am J Kidney Dis 1995;26:678-90]. Thus, the molecular and cellular mechanisms underpinning EMT are both an essential feature of Metazoan development and an important area of biomedical research. In this review, we discuss the common molecular and cellular mechanisms involved in EMT in both cases.
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Affiliation(s)
- Buzz Baum
- Department of Cell and Developmental Biology, UCL, London, UK
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43
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Boissel L, Houssin N, Chikh A, Rynditch A, Van Hove L, Moreau J. Recruitment of Cdc42 through the GAP domain of RLIP participates in remodeling of the actin cytoskeleton and is involved in Xenopus gastrulation. Dev Biol 2007; 312:331-43. [DOI: 10.1016/j.ydbio.2007.09.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 09/07/2007] [Accepted: 09/17/2007] [Indexed: 12/23/2022]
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44
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Murray MJ, Saint R. Photoactivatable GFP resolves Drosophila mesoderm migration behaviour. Development 2007; 134:3975-83. [PMID: 17942486 DOI: 10.1242/dev.005389] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mesoderm migration is a pivotal event in the early embryonic development of animals. One of the best-studied examples occurs during Drosophila gastrulation. Here, mesodermal cells invaginate, undergo an epithelial-to-mesenchymal transition (EMT), and spread out dorsally over the inner surface of the ectoderm. Although several genes required for spreading have been identified, our inability to visualise mesodermal cells in living embryos has left us to speculate about the cell rearrangements involved. Several mechanisms, such as chemotaxis towards a dorsally expressed attractant, differential affinity between mesodermal cells and the ectoderm, and convergent extension, have been proposed. Here we resolve the behaviour of Drosophila mesodermal cells in live embryos using photoactivatable-GFP fused to alpha-Tubulin (PAGFP-Tub). By photoactivating presumptive mesodermal cells before gastrulation, we could observe their migration over non-fluorescent ectodermal cells. We show that the outermost (outer) cells, which are in contact with the ectoderm, migrate dorsolaterally as a group but can be overtaken by more internal (inner) cells. Using laser-photoactivation of individual cells, we then show that inner cells adjacent to the centre of the furrow migrate dorsolaterally away from the midline to reach dorsal positions, while cells at the centre of the furrow disperse randomly across the mesoderm, before intercalating with outer cells. These movements are dependent on the FGF receptor Heartless. The results indicate that chemotactic movement and differential affinity are the primary drivers of mesodermal cell spreading. These characterisations pave the way for a more detailed analysis of gene function during early mesoderm development.
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Affiliation(s)
- Michael J Murray
- The ARC Special Research Centre for the Molecular Genetics of Development and Molecular Genetics and Evolution Group, Research School of Biological Sciences, The Australian National University, Canberra, ACT 2601, Australia
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45
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Ilagan R, Abu-Issa R, Brown D, Yang YP, Jiao K, Schwartz RJ, Klingensmith J, Meyers EN. Fgf8 is required for anterior heart field development. Development 2006; 133:2435-45. [PMID: 16720880 DOI: 10.1242/dev.02408] [Citation(s) in RCA: 187] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the mouse embryo, the splanchnic mesodermal cells of the anterior heart field (AHF) migrate from the pharynx to contribute to the early myocardium of the outflow tract (OT) and right ventricle (RV). Recent studies have attempted to distinguish the AHF from other precardiac populations, and to determine the genetic and molecular mechanisms that regulate its development. Here, we have used an Fgf8lacZ allele to demonstrate that Fgf8is expressed within the developing AHF. In addition, we use both a hypomorphic Fgf8 allele (Fgf8neo) and Cre-mediated gene ablation to show that Fgf8 is essential for the survival and proliferation of the AHF. Nkx2.5Cre is expressed in the AHF, primary heart tube and pharyngeal endoderm, while TnT-Cre is expressed only within the specified heart tube myocardium. Deletion of Fgf8 by Nkx2.5Cre results in a significant loss of the Nkx2.5Cre lineage and severe OT and RV truncations by E9.5, while the remaining heart chambers (left ventricle and atria) are grossly normal. These defects result from significant decreases in cell proliferation and aberrant cell death in both the pharyngeal endoderm and splanchnic mesoderm. By contrast, ablation of Fgf8 in the TnT-Cre domain does not result in OT or RV defects, providing strong evidence that Fgf8 expression is crucial in the pharyngeal endoderm and/or overlying splanchnic mesoderm of the AHF at a stage prior to heart tube elongation. Analysis of downstream signaling components, such as phosphorylated-Erk and Pea3, identifies the AHF splanchnic mesoderm itself as a target for Fgf8 signaling.
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Affiliation(s)
- Roger Ilagan
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
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46
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Morita K, Hirono K, Han M. The Caenorhabditis elegans ect-2 RhoGEF gene regulates cytokinesis and migration of epidermal P cells. EMBO Rep 2006; 6:1163-8. [PMID: 16170304 PMCID: PMC1369201 DOI: 10.1038/sj.embor.7400533] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 08/17/2005] [Accepted: 08/17/2005] [Indexed: 11/08/2022] Open
Abstract
A reduction-of-function mutation in ect-2 was isolated as a suppressor of the Multivulva phenotype of a lin-31 mutation. Analysis using markers indicates that this mutation causes defects in both the cytokinesis and migration of epidermal P cells, phenotypes similar to those caused by expressing a rho-1 dominant-negative construct. ect-2 encodes the Caenorhabditis elegans orthologue of the mouse Ect2 and Drosophila Pebble that function as guanine nucleotide exchange factors (GEFs) for Rho GTPases. The ect-2Colon, two colonsGFP reporter is expressed in embryonic cells and P cells. RNA interference of ect-2 causes sterility and embryonic lethality, in addition to the P-cell defects. We have determined the lesions of two ect-2 alleles, and described their differences in phenotypes in specific tissues. We propose a model in which ECT-2GEF not only activates RHO-1 for P-cell cytokinesis, but also collaborates with UNC-73GEF and at least two Rac proteins to regulate P-cell migration.
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Affiliation(s)
- Kiyokazu Morita
- Department of MCD Biology, Howard Hughes Medical Institute, University of Colorado, Boulder, Colorado 80309, USA
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47
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Canevascini S, Marti M, Fröhli E, Hajnal A. The Caenorhabditis elegans homologue of the proto-oncogene ect-2 positively regulates RAS signalling during vulval development. EMBO Rep 2006; 6:1169-75. [PMID: 16270101 PMCID: PMC1369209 DOI: 10.1038/sj.embor.7400574] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Revised: 09/22/2005] [Accepted: 10/10/2005] [Indexed: 11/08/2022] Open
Abstract
Guanine nucleotide exchange factors (GEFs) regulate the activity of small GTP-binding proteins in a variety of biological processes. We have identified a gain-of-function mutation in the Caenorhabditis elegans GEF ect-2, the homologue of the mammalian ect2 proto-oncogene that has an essential role during cytokinesis. Here, we report that, in addition to its known function during mitosis, ECT-2 promotes the specification of the primary vulval cell fate by activating RAS/mitogen-activated protein kinase (MAPK) signalling before the end of the S-phase. Epistasis analysis indicates that ECT-2 crosstalks to the canonical RAS/MAPK cascade upstream of the RAS GEF SOS-1 by means of a RHO-1 signalling pathway. Our results raise the possibility that the transforming activity of the mammalian ect-2 oncogene could be due to hyperactivation of the RAS/MAPK pathway.
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Affiliation(s)
- Stefano Canevascini
- Institute of Zoology, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Mark Marti
- Institute of Zoology, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Erika Fröhli
- Institute of Zoology, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Alex Hajnal
- Institute of Zoology, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
- Tel: +41 44 6354854; Fax: +41 44 6356878; E-mail:
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48
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Abstract
As the gateway to shaping the body plan, gastrulation is an important problem in developmental biology, and recent advances in cell biology have overcome some of the limitations of past approaches to learning how genes control reshaping of embryonic tissues. The use of fluorescent tracer dyes and live cell imaging methods to evaluate at the cellular level the results of genetic and molecular manipulations has advanced our understanding of the cell motility and contact behavior underlying tissue remodeling during gastrulation.
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Affiliation(s)
- Ray Keller
- Department of Biology and Morphogenesis and Regenerative Medicine Institute, University of Virginia, Charlottesville, Virginia 22904, USA.
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49
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Chung HA, Hyodo-Miura J, Nagamune T, Ueno N. FGF signal regulates gastrulation cell movements and morphology through its target NRH. Dev Biol 2005; 282:95-110. [PMID: 15936332 DOI: 10.1016/j.ydbio.2005.02.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 01/28/2005] [Accepted: 02/26/2005] [Indexed: 01/19/2023]
Abstract
We used cDNA microarray analysis to screen for FGF target genes in Xenopus embryos treated with the FGFR1 inhibitor SU5402, and identified neurotrophin receptor homolog (NRH) as an FGF target. Causing gain of NRH function by NRH mRNA or loss of NRH function using a Morpholino antisense-oligonucleotide (Mo) led to gastrulation defects without affecting mesoderm differentiation. Depletion of NRH by the Mo perturbed the polarization of cells in the dorsal marginal zone (DMZ), thereby inhibiting the intercalation of the cells during convergent extension as well as the filopodia formation on DMZ cells. Deletion analysis showed that the carboxyl-terminal region of NRH, which includes the "death domain," was necessary and sufficient to rescue gastrulation defects and to induce the protrusive cell morphology. Furthermore, we found that the FGF signal was both capable of inducing filopodia in animal cap cells, where they do not normally form, and necessary for filopodia formation in DMZ cells. Finally, we demonstrated that FGF required NRH function to induce normal DMZ cell morphology. This study is the first to identify an in vivo role for FGF in the regulation of cell morphology, and we have linked this function to the control of gastrulation cell movements via NRH.
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Affiliation(s)
- Hyeyoung A Chung
- Department of Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan
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50
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Abstract
The development of human cancer is a multistep process, involving the cooperation of mutations in signalling, cell-cycle and cell-death pathways, as well as interactions between the tumour and the tumour microenvironment. To dissect the steps of tumorigenesis, simple animal models are needed. This article discusses the use of the genetically amenable, multicellular organism, the vinegar fly Drosophila melanogaster. In particular, recent studies have highlighted the power of D. melanogaster for examining cooperative interactions between tumour suppressors and oncogenes and for generating in vivo models of tumour development and metastasis.
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Affiliation(s)
- Anthony M Brumby
- Cell Cycle and Development Group, Research Division, Peter MacCallum Cancer Centre, 7 St Andrew's Place, 3002, East Melbourne, Victoria, Australia.
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