1
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Li L, Zhang N, Beati SAH, De Las Heras Chanes J, di Pietro F, Bellaiche Y, Müller HAJ, Großhans J. Kinesin-1 patterns Par-1 and Rho signaling at the cortex of syncytial embryos of Drosophila. J Cell Biol 2024; 223:e202206013. [PMID: 37955925 PMCID: PMC10641515 DOI: 10.1083/jcb.202206013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 03/23/2023] [Accepted: 10/18/2023] [Indexed: 11/14/2023] Open
Abstract
The cell cortex of syncytial Drosophila embryos is patterned into cap and intercap regions by centrosomes, specific sets of proteins that are restricted to their respective regions by unknown mechanisms. Here, we found that Kinesin-1 is required for the restriction of plus- and minus-ends of centrosomal and non-centrosomal microtubules to the cap region, marked by EB1 and Patronin/Shot, respectively. Kinesin-1 also directly or indirectly restricts proteins and Rho signaling to the intercap, including the RhoGEF Pebble, Dia, Myosin II, Capping protein-α, and the polarity protein Par-1. Furthermore, we found that Par-1 is required for cap restriction of Patronin/Shot, and vice versa Patronin, for Par-1 enrichment at the intercap. In summary, our data support a model that Kinesin-1 would mediate the restriction of centrosomal and non-centrosomal microtubules to a region close to the centrosomes and exclude Rho signaling and Par-1. In addition, mutual antagonistic interactions would refine and maintain the boundary between cap and intercap and thus generate a distinct cortical pattern.
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Affiliation(s)
- Long Li
- Department of Biology, Philipps University, Marburg, Germany
| | - Na Zhang
- Department of Biology, Philipps University, Marburg, Germany
| | - Seyed Amir Hamze Beati
- Division of Developmental Genetics, Institute for Biology, University of Kassel, Kassel, Germany
| | - Jose De Las Heras Chanes
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Florencia di Pietro
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Yohanns Bellaiche
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 3215, Inserm U934, Genetics and Developmental Biology , Paris, France
| | - Hans-Arno J Müller
- Division of Developmental Genetics, Institute for Biology, University of Kassel, Kassel, Germany
| | - Jörg Großhans
- Department of Biology, Philipps University, Marburg, Germany
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2
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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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3
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Lauri A, Fasano G, Venditti M, Dallapiccola B, Tartaglia M. In vivo Functional Genomics for Undiagnosed Patients: The Impact of Small GTPases Signaling Dysregulation at Pan-Embryo Developmental Scale. Front Cell Dev Biol 2021; 9:642235. [PMID: 34124035 PMCID: PMC8194860 DOI: 10.3389/fcell.2021.642235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/12/2021] [Indexed: 12/24/2022] Open
Abstract
While individually rare, disorders affecting development collectively represent a substantial clinical, psychological, and socioeconomic burden to patients, families, and society. Insights into the molecular mechanisms underlying these disorders are required to speed up diagnosis, improve counseling, and optimize management toward targeted therapies. Genome sequencing is now unveiling previously unexplored genetic variations in undiagnosed patients, which require functional validation and mechanistic understanding, particularly when dealing with novel nosologic entities. Functional perturbations of key regulators acting on signals' intersections of evolutionarily conserved pathways in these pathological conditions hinder the fine balance between various developmental inputs governing morphogenesis and homeostasis. However, the distinct mechanisms by which these hubs orchestrate pathways to ensure the developmental coordinates are poorly understood. Integrative functional genomics implementing quantitative in vivo models of embryogenesis with subcellular precision in whole organisms contribute to answering these questions. Here, we review the current knowledge on genes and mechanisms critically involved in developmental syndromes and pediatric cancers, revealed by genomic sequencing and in vivo models such as insects, worms and fish. We focus on the monomeric GTPases of the RAS superfamily and their influence on crucial developmental signals and processes. We next discuss the effectiveness of exponentially growing functional assays employing tractable models to identify regulatory crossroads. Unprecedented sophistications are now possible in zebrafish, i.e., genome editing with single-nucleotide precision, nanoimaging, highly resolved recording of multiple small molecules activity, and simultaneous monitoring of brain circuits and complex behavioral response. These assets permit accurate real-time reporting of dynamic small GTPases-controlled processes in entire organisms, owning the potential to tackle rare disease mechanisms.
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Affiliation(s)
- Antonella Lauri
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | | | | | | | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
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4
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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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5
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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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6
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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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7
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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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8
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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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9
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Saykali B, Mathiah N, Nahaboo W, Racu ML, Hammou L, Defrance M, Migeotte I. Distinct mesoderm migration phenotypes in extra-embryonic and embryonic regions of the early mouse embryo. eLife 2019; 8:42434. [PMID: 30950395 PMCID: PMC6450669 DOI: 10.7554/elife.42434] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 03/11/2019] [Indexed: 12/22/2022] Open
Abstract
In mouse embryo gastrulation, epiblast cells delaminate at the primitive streak to form mesoderm and definitive endoderm, through an epithelial-mesenchymal transition. Mosaic expression of a membrane reporter in nascent mesoderm enabled recording cell shape and trajectory through live imaging. Upon leaving the streak, cells changed shape and extended protrusions of distinct size and abundance depending on the neighboring germ layer, as well as the region of the embryo. Embryonic trajectories were meandrous but directional, while extra-embryonic mesoderm cells showed little net displacement. Embryonic and extra-embryonic mesoderm transcriptomes highlighted distinct guidance, cytoskeleton, adhesion, and extracellular matrix signatures. Specifically, intermediate filaments were highly expressed in extra-embryonic mesoderm, while live imaging for F-actin showed abundance of actin filaments in embryonic mesoderm only. Accordingly, Rhoa or Rac1 conditional deletion in mesoderm inhibited embryonic, but not extra-embryonic mesoderm migration. Overall, this indicates separate cytoskeleton regulation coordinating the morphology and migration of mesoderm subpopulations.
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Affiliation(s)
| | | | - Wallis Nahaboo
- IRIBHM, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Latifa Hammou
- IRIBHM, Université Libre de Bruxelles, Brussels, Belgium
| | - Matthieu Defrance
- Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles, Brussels, Belgium
| | - Isabelle Migeotte
- IRIBHM, Université Libre de Bruxelles, Brussels, Belgium.,Walloon Excellence in Lifesciences and Biotechnology, Wallonia, Belgium
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10
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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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11
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Rosa A, Vlassaks E, Pichaud F, Baum B. Ect2/Pbl acts via Rho and polarity proteins to direct the assembly of an isotropic actomyosin cortex upon mitotic entry. Dev Cell 2015; 32:604-16. [PMID: 25703349 PMCID: PMC4359025 DOI: 10.1016/j.devcel.2015.01.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 10/06/2014] [Accepted: 01/14/2015] [Indexed: 02/06/2023]
Abstract
Entry into mitosis is accompanied by profound changes in cortical actomyosin organization. Here, we delineate a pathway downstream of the RhoGEF Pbl/Ect2 that directs this process in a model epithelium. Our data suggest that the release of Pbl/Ect2 from the nucleus at mitotic entry drives Rho-dependent activation of Myosin-II and, in parallel, induces a switch from Arp2/3 to Diaphanous-mediated cortical actin nucleation that depends on Cdc42, aPKC, and Par6. At the same time, the mitotic relocalization of these apical protein complexes to more lateral cell surfaces enables Cdc42/aPKC/Par6 to take on a mitosis-specific function—aiding the assembly of a relatively isotropic metaphase cortex. Together, these data reveal how the repolarization and remodeling of the actomyosin cortex are coordinated upon entry into mitosis to provide cells with the isotropic and rigid form they need to undergo faithful chromosome segregation and division in a crowded tissue environment. Pbl/Ect2 drives a shift in epithelial polarity upon entry into mitosis Lateral spreading of Cdc42/aPKC/Par6 aids assembly of an isotropic metaphase cortex Mitosis triggers a switch from Arp2/3 to Dia-mediated cortical actin nucleation
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Affiliation(s)
- André Rosa
- MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK; Graduate Program in Areas of Basic and Applied Biology (GABBA), University of Porto, 4200-465 Porto, Portugal
| | - Evi Vlassaks
- MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Franck Pichaud
- MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Buzz Baum
- MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK.
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12
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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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13
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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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14
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Functional analysis of the Drosophila embryonic germ cell transcriptome by RNA interference. PLoS One 2014; 9:e98579. [PMID: 24896584 PMCID: PMC4045815 DOI: 10.1371/journal.pone.0098579] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/05/2014] [Indexed: 11/19/2022] Open
Abstract
In Drosophila melanogaster, primordial germ cells are specified at the posterior pole of the very early embryo. This process is regulated by the posterior localized germ plasm that contains a large number of RNAs of maternal origin. Transcription in the primordial germ cells is actively down-regulated until germ cell fate is established. Bulk expression of the zygotic genes commences concomitantly with the degradation of the maternal transcripts. Thus, during embryogenesis, maternally provided and zygotically transcribed mRNAs determine germ cell development collectively. In an effort to identify novel genes involved in the regulation of germ cell behavior, we carried out a large-scale RNAi screen targeting both maternal and zygotic components of the embryonic germ line transcriptome. We identified 48 genes necessary for distinct stages in germ cell development. We found pebble and fascetto to be essential for germ cell migration and germ cell division, respectively. Our data uncover a previously unanticipated role of mei-P26 in maintenance of embryonic germ cell fate. We also performed systematic co-RNAi experiments, through which we found a low rate of functional redundancy among homologous gene pairs. As our data indicate a high degree of evolutionary conservation in genetic regulation of germ cell development, they are likely to provide valuable insights into the biology of the germ line in general.
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15
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Kitazawa D, Matsuo T, Kaizuka K, Miyauchi C, Hayashi D, Inoue YH. Orbit/CLASP is required for myosin accumulation at the cleavage furrow in Drosophila male meiosis. PLoS One 2014; 9:e93669. [PMID: 24850412 PMCID: PMC4029619 DOI: 10.1371/journal.pone.0093669] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 03/07/2014] [Indexed: 01/24/2023] Open
Abstract
Peripheral microtubules (MTs) near the cell cortex are essential for the positioning and continuous constriction of the contractile ring (CR) in cytokinesis. Time-lapse observations of Drosophila male meiosis showed that myosin II was first recruited along the cell cortex independent of MTs. Then, shortly after peripheral MTs made contact with the equatorial cortex, myosin II was concentrated there in a narrow band. After MT contact, anillin and F-actin abruptly appeared on the equatorial cortex, simultaneously with myosin accumulation. We found that the accumulation of myosin did not require centralspindlin, but was instead dependent on Orbit, a Drosophila ortholog of the MT plus-end tracking protein CLASP. This protein is required for stabilization of central spindle MTs, which are essential for cytokinesis. Orbit was also localized in a mid-zone of peripheral MTs, and was concentrated in a ring at the equatorial cortex during late anaphase. Fluorescence resonance energy transfer experiments indicated that Orbit is closely associated with F-actin in the CR. We also showed that the myosin heavy chain was in close proximity with Orbit in the cleavage furrow region. Centralspindlin was dispensable in Orbit ring formation. Instead, the Polo-KLP3A/Feo complex was required for the Orbit accumulation independently of the Orbit MT-binding domain. However, orbit mutations of consensus sites for the phosphorylation of Cdk1 or Polo did not influence the Orbit accumulation, suggesting an indirect regulatory role of these protein kinases in Orbit localization. Orbit was also necessary for the maintenance of the CR. Our data suggest that Orbit plays an essential role as a connector between MTs and the CR in Drosophila male meiosis.
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Affiliation(s)
- Daishi Kitazawa
- Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Tatsuru Matsuo
- Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Kana Kaizuka
- Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Chie Miyauchi
- Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Daisuke Hayashi
- Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
| | - Yoshihiro H. Inoue
- Insect Biomedical Research Center, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
- * E-mail:
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16
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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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17
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Duan G, Saint RB, Helliwell CA, Behm CA, Wang MB, Waterhouse PM, Gordon KHJ. C. elegans RNA-dependent RNA polymerases rrf-1 and ego-1 silence Drosophila transgenes by differing mechanisms. Cell Mol Life Sci 2013; 70:1469-81. [PMID: 23224429 PMCID: PMC11113355 DOI: 10.1007/s00018-012-1218-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 11/19/2012] [Accepted: 11/22/2012] [Indexed: 10/27/2022]
Abstract
Drosophila possesses the core gene silencing machinery but, like all insects, lacks the canonical RNA-dependent RNA polymerases (RdRps) that in C. elegans either trigger or enhance two major small RNA-dependent gene silencing pathways. Introduction of two different nematode RdRps into Drosophila showed them to be functional, resulting in differing silencing activities. While RRF-1 enhanced transitive dsRNA-dependent silencing, EGO-1 triggered dsRNA-independent silencing, specifically of transgenes. The strain w; da-Gal4; UAST-ego-1, constitutively expressing ego-1, is capable of silencing transgene including dsRNA hairpin upon a single cross, which created a powerful tool for research in Drosophila. In C. elegans, EGO-1 is involved in transcriptional gene silencing (TGS) of chromosome regions that are unpaired during meiosis. There was no opportunity for meiotic interactions involving EGO-1 in Drosophila that would explain the observed transgene silencing. Transgene DNA is, however, unpaired during the pairing of chromosomes in embryonic mitosis that is an unusual characteristic of Diptera, suggesting that in Drosophila, EGO-1 triggers transcriptional silencing of unpaired DNA during embryonic mitosis.
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Affiliation(s)
- Guowen Duan
- CSIRO Ecosystem Sciences, Clunies Ross St., Canberra, ACT, 2601, Australia.
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18
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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: 46] [Impact Index Per Article: 4.2] [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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19
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Kotadia S, Montembault E, Sullivan W, Royou A. Cell elongation is an adaptive response for clearing long chromatid arms from the cleavage plane. ACTA ACUST UNITED AC 2013. [PMID: 23185030 PMCID: PMC3514784 DOI: 10.1083/jcb.201208041] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A cortical myosin-dependent mechanism induces cell elongation to ensure clearance of trailing chromatids from the cleavage plane at the correct time during cytokinesis. Chromosome segregation must be coordinated with cell cleavage to ensure correct transmission of the genome to daughter cells. Here we identify a novel mechanism by which Drosophila melanogaster neuronal stem cells coordinate sister chromatid segregation with cleavage furrow ingression. Cells adapted to a dramatic increase in chromatid arm length by transiently elongating during anaphase/telophase. The degree of cell elongation correlated with the length of the trailing chromatid arms and was concomitant with a slight increase in spindle length and an enlargement of the zone of cortical myosin distribution. Rho guanine-nucleotide exchange factor (Pebble)–depleted cells failed to elongate during segregation of long chromatids. As a result, Pebble-depleted adult flies exhibited morphological defects likely caused by cell death during development. These studies reveal a novel pathway linking trailing chromatid arms and cortical myosin that ensures the clearance of chromatids from the cleavage plane at the appropriate time during cytokinesis, thus preserving genome integrity.
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Affiliation(s)
- Shaila Kotadia
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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20
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Chan E, Nance J. Mechanisms of CDC-42 activation during contact-induced cell polarization. J Cell Sci 2013; 126:1692-702. [PMID: 23424200 DOI: 10.1242/jcs.124594] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polarization of early embryos provides a foundation to execute essential patterning and morphogenetic events. In Caenorhabditis elegans, cell contacts polarize early embryos along their radial axis by excluding the cortical polarity protein PAR-6 from sites of cell contact, thereby restricting PAR-6 to contact-free cell surfaces. Radial polarization requires the cortically enriched Rho GTPase CDC-42, which in its active form recruits PAR-6 through direct binding. The Rho GTPase activating protein (RhoGAP) PAC-1, which localizes specifically to cell contacts, triggers radial polarization by inactivating CDC-42 at these sites. The mechanisms responsible for activating CDC-42 at contact-free surfaces are unknown. Here, in an overexpression screen of Rho guanine nucleotide exchange factors (RhoGEFs), which can activate Rho GTPases, we identify CGEF-1 and ECT-2 as RhoGEFs that act through CDC-42 to recruit PAR-6 to the cortex. We show that ECT-2 and CGEF-1 localize to the cell surface and that removing their activity causes a reduction in levels of cortical PAR-6. Through a structure-function analysis, we show that the tandem DH-PH domains of CGEF-1 and ECT-2 are sufficient for GEF activity, but that regions outside of these domains target each protein to the cell surface. Finally, we provide evidence suggesting that the N-terminal region of ECT-2 may direct its in vivo preference for CDC-42 over another known target, the Rho GTPase RHO-1. We propose that radial polarization results from a competition between RhoGEFs, which activate CDC-42 throughout the cortex, and the RhoGAP PAC-1, which inactivates CDC-42 at cell contacts.
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Affiliation(s)
- Emily Chan
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
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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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Herszterg S, Leibfried A, Bosveld F, Martin C, Bellaiche Y. Interplay between the Dividing Cell and Its Neighbors Regulates Adherens Junction Formation during Cytokinesis in Epithelial Tissue. Dev Cell 2013; 24:256-70. [DOI: 10.1016/j.devcel.2012.11.019] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 11/15/2012] [Accepted: 11/17/2012] [Indexed: 12/31/2022]
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23
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Khoo P, Allan K, Willoughby L, Brumby AM, Richardson HE. In Drosophila, RhoGEF2 cooperates with activated Ras in tumorigenesis through a pathway involving Rho1-Rok-Myosin-II and JNK signalling. Dis Model Mech 2013; 6:661-78. [PMID: 23324326 PMCID: PMC3634650 DOI: 10.1242/dmm.010066] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The Ras oncogene contributes to ≈ 30% of human cancers, but alone is not sufficient for tumorigenesis. In a Drosophila screen for oncogenes that cooperate with an activated allele of Ras (Ras(ACT)) to promote tissue overgrowth and invasion, we identified the GTP exchange factor RhoGEF2, an activator of Rho-family signalling. Here, we show that RhoGEF2 also cooperates with an activated allele of a downstream effector of Ras, Raf (Raf(GOF)). We dissect the downstream pathways through which RhoGEF2 cooperates with Ras(ACT) (and Raf(GOF)), and show that RhoGEF2 requires Rho1, but not Rac, for tumorigenesis. Furthermore, of the Rho1 effectors, we show that RhoGEF2 + Ras (Raf)-mediated tumorigenesis requires the Rho kinase (Rok)-Myosin-II pathway, but not Diaphanous, Lim kinase or protein kinase N. The Rho1-Rok-Myosin-II pathway leads to the activation of Jun kinase (JNK), in cooperation with Ras(ACT). Moreover, we show that activation of Rok or Myosin II, using constitutively active transgenes, is sufficient for cooperative tumorigenesis with Ras(ACT), and together with Ras(ACT) leads to strong activation of JNK. Our results show that Rok-Myosin-II activity is necessary and sufficient for Ras-mediated tumorigenesis. Our observation that activation of Myosin II, which regulates Filamentous actin (F-actin) contractility without affecting F-actin levels, cooperates with Ras(ACT) to promote JNK activation and tumorigenesis, suggests that increased cell contractility is a key factor in tumorigenesis. Furthermore, we show that signalling via the Tumour necrosis factor (TNF; also known as Egr)-ligand-JNK pathway is most likely the predominant pathway that activates JNK upon Rok activation. Overall, our analysis highlights the need for further analysis of the Rok-Myosin-II pathway in cooperation with Ras in human cancers.
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Affiliation(s)
- Peytee Khoo
- Cell Cycle and Development Laboratory, Research Division, Peter MacCallum Cancer Center, Melbourne, Victoria, Australia
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24
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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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25
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Matthews H, Delabre U, Rohn J, Guck J, Kunda P, Baum B. Changes in Ect2 localization couple actomyosin-dependent cell shape changes to mitotic progression. Dev Cell 2012; 23:371-83. [PMID: 22898780 PMCID: PMC3763371 DOI: 10.1016/j.devcel.2012.06.003] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 04/04/2012] [Accepted: 06/05/2012] [Indexed: 12/17/2022]
Abstract
As they enter mitosis, animal cells undergo profound actin-dependent changes in shape to become round. Here we identify the Cdk1 substrate, Ect2, as a central regulator of mitotic rounding, thus uncovering a link between the cell-cycle machinery that drives mitotic entry and its accompanying actin remodeling. Ect2 is a RhoGEF that plays a well-established role in formation of the actomyosin contractile ring at mitotic exit, through the local activation of RhoA. We find that Ect2 first becomes active in prophase, when it is exported from the nucleus into the cytoplasm, activating RhoA to induce the formation of a mechanically stiff and rounded metaphase cortex. Then, at anaphase, binding to RacGAP1 at the spindle midzone repositions Ect2 to induce local actomyosin ring formation. Ect2 localization therefore defines the stage-specific changes in actin cortex organization critical for accurate cell division.
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Affiliation(s)
- Helen K. Matthews
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
| | - Ulysse Delabre
- Department of Physics, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
- PCC Curie, Institut Curie/CNRS/Université Paris 6 - UMR 168, 26 rue d'Ulm, 75248 Paris, France
| | - Jennifer L. Rohn
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
| | - Jochen Guck
- Department of Physics, Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - Patricia Kunda
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
| | - Buzz Baum
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK
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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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Frenette P, Haines E, Loloyan M, Kinal M, Pakarian P, Piekny A. An anillin-Ect2 complex stabilizes central spindle microtubules at the cortex during cytokinesis. PLoS One 2012; 7:e34888. [PMID: 22514687 PMCID: PMC3325936 DOI: 10.1371/journal.pone.0034888] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 03/09/2012] [Indexed: 12/31/2022] Open
Abstract
Cytokinesis occurs due to the RhoA-dependent ingression of an actomyosin ring. During anaphase, the Rho GEF (guanine nucleotide exchange factor) Ect2 is recruited to the central spindle via its interaction with MgcRacGAP/Cyk-4, and activates RhoA in the central plane of the cell. Ect2 also localizes to the cortex, where it has access to RhoA. The N-terminus of Ect2 binds to Cyk-4, and the C-terminus contains conserved DH (Dbl homologous) and PH (Pleckstrin Homology) domains with GEF activity. The PH domain is required for Ect2's cortical localization, but its molecular function is not known. In cultured human cells, we found that the PH domain interacts with anillin, a contractile ring protein that scaffolds actin and myosin and interacts with RhoA. The anillin-Ect2 interaction may require Ect2's association with lipids, since a novel mutation in the PH domain, which disrupts phospholipid association, weakens their interaction. An anillin-RacGAP50C (homologue of Cyk-4) complex was previously described in Drosophila, which may crosslink the central spindle to the cortex to stabilize the position of the contractile ring. Our data supports an analogous function for the anillin-Ect2 complex in human cells and one hypothesis is that this complex has functionally replaced the Drosophila anillin-RacGAP50C complex. Complexes between central spindle proteins and cortical proteins could regulate the position of the contractile ring by stabilizing microtubule-cortical interactions at the division plane to ensure the generation of active RhoA in a discrete zone.
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Affiliation(s)
- Paul Frenette
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Eric Haines
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Michael Loloyan
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Mena Kinal
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Paknoosh Pakarian
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, Quebec, Canada
- * E-mail:
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28
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Plageman TF, Chauhan BK, Yang C, Jaudon F, Shang X, Zheng Y, Lou M, Debant A, Hildebrand JD, Lang RA. A Trio-RhoA-Shroom3 pathway is required for apical constriction and epithelial invagination. Development 2011; 138:5177-88. [PMID: 22031541 DOI: 10.1242/dev.067868] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Epithelial invagination is a common feature of embryogenesis. An example of invagination morphogenesis occurs during development of the early eye when the lens placode forms the lens pit. This morphogenesis is accompanied by a columnar-to-conical cell shape change (apical constriction or AC) and is known to be dependent on the cytoskeletal protein Shroom3. Because Shroom3-induced AC can be Rock1/2 dependent, we hypothesized that during lens invagination, RhoA, Rock and a RhoA guanine nucleotide exchange factor (RhoA-GEF) would also be required. In this study, we show that Rock activity is required for lens pit invagination and that RhoA activity is required for Shroom3-induced AC. We demonstrate that RhoA, when activated and targeted apically, is sufficient to induce AC and that RhoA plays a key role in Shroom3 apical localization. Furthermore, we identify Trio as a RhoA-GEF required for Shroom3-dependent AC in MDCK cells and in the lens pit. Collectively, these data indicate that a Trio-RhoA-Shroom3 pathway is required for AC during lens pit invagination.
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Affiliation(s)
- Timothy F Plageman
- The Visual Systems Group, Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH 45229, USA
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29
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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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30
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Migeotte I, Grego-Bessa J, Anderson KV. Rac1 mediates morphogenetic responses to intercellular signals in the gastrulating mouse embryo. Development 2011; 138:3011-20. [PMID: 21693517 DOI: 10.1242/dev.059766] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The establishment of the mammalian body plan depends on signal-regulated cell migration and adhesion, processes that are controlled by the Rho family of GTPases. Here we use a conditional allele of Rac1, the only Rac gene expressed early in development, to define its roles in the gastrulating mouse embryo. Embryos that lack Rac1 in the epiblast (Rac1Δepi) initiate development normally: the signaling pathways required for gastrulation are active, definitive endoderm and all classes of mesoderm are specified, and the neural plate is formed. After the initiation of gastrulation, Rac1Δepi embryos have an enlarged primitive streak, make only a small amount of paraxial mesoderm, and the lateral anlage of the heart do not fuse at the midline. Because these phenotypes are also seen in Nap1 mutants, we conclude that Rac1 acts upstream of the Nap1/WAVE complex to promote migration of the nascent mesoderm. In addition to migration phenotypes, Rac1Δepi cells fail to adhere to matrix, which leads to extensive cell death. Cell death is largely rescued in Rac1Δepi mutants that are heterozygous for a null mutation in Pten, providing evidence that Rac1 is required to link signals from the basement membrane to activation of the PI3K-Akt pathway in vivo. Surprisingly, the frequency of apoptosis is greater in the anterior half of the embryo, suggesting that cell survival can be promoted either by matrix adhesion or by signals from the posterior primitive streak. Rac1 also has essential roles in morphogenesis of the posterior notochordal plate (the node) and the midline.
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Affiliation(s)
- Isabelle Migeotte
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA
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31
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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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32
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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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33
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Abstract
Drosophila melanogaster offers a powerful system for the analysis of cell migration. In the embryo, -pluripotent cells of the mesodermal and endodermal primordia undergo epithelial-mesenchymal transitions and cell migration, while primordial germ cells migrate through an endodermal barrier to form the gonads. Visualisation of these migrations has traditionally been achieved by staining fixed embryos at different developmental stages or through live imaging of cells using tissue-specific expression of marker fluorescent proteins. More recently, photoactivatable fluorescence proteins have allowed the labelling of small groups of cells or single cells so that their migratory patterns and fate can be followed. By fusing the photoactivatable fluorescent protein to proteins that mark different subcellular components, it is now possible to visualise different aspects of the cells as they migrate. Here, we review previous studies of the migration of pluripotent embryonic cells and describe, in detail, methods for visualising these cells.
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Affiliation(s)
- Michael J Murray
- Molecular Genetics and Evolution, Research School of Biological Sciences, Australian National University, Acton, ACT, Australia
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34
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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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