1
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Tam R, Harris TJC. Reshaping the Syncytial Drosophila Embryo with Cortical Actin Networks: Four Main Steps of Early Development. Results Probl Cell Differ 2024; 71:67-90. [PMID: 37996673 DOI: 10.1007/978-3-031-37936-9_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Drosophila development begins as a syncytium. The large size of the one-cell embryo makes it ideal for studying the structure, regulation, and effects of the cortical actin cytoskeleton. We review four main steps of early development that depend on the actin cortex. At each step, dynamic remodelling of the cortex has specific effects on nuclei within the syncytium. During axial expansion, a cortical actomyosin network assembles and disassembles with the cell cycle, generating cytoplasmic flows that evenly distribute nuclei along the ovoid cell. When nuclei move to the cell periphery, they seed Arp2/3-based actin caps which grow into an array of dome-like compartments that house the nuclei as they divide at the cell cortex. To separate germline nuclei from the soma, posterior germ plasm induces full cleavage of mono-nucleated primordial germ cells from the syncytium. Finally, zygotic gene expression triggers formation of the blastoderm epithelium via cellularization and simultaneous division of ~6000 mono-nucleated cells from a single internal yolk cell. During these steps, the cortex is regulated in space and time, gains domain and sub-domain structure, and undergoes mesoscale interactions that lay a structural foundation of animal development.
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Affiliation(s)
- Rebecca Tam
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada.
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2
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Dey B, Mitra D, Das T, Sherlekar A, Balaji R, Rikhy R. Adhesion and Polarity protein distribution-regulates hexagon dominated plasma membrane organization in Drosophila blastoderm embryos. Genetics 2023; 225:iyad184. [PMID: 37804533 DOI: 10.1093/genetics/iyad184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 08/29/2023] [Accepted: 09/25/2023] [Indexed: 10/09/2023] Open
Abstract
Epithelial cells contain polarity complexes on the lateral membrane and are organized in a hexagon-dominated polygonal array. The mechanisms regulating the organization of polygonal architecture in metazoan embryogenesis are not completely understood. Drosophila embryogenesis enables mechanistic analysis of epithelial polarity formation and its impact on polygonal organization. The plasma membrane (PM) of syncytial Drosophila blastoderm embryos is organized as a polygonal array with pseudocleavage furrow formation during the almost synchronous cortical division cycles. We find that polygonal (PM) organization arises in the metaphase (MP) of division cycle 11, and hexagon dominance occurs with an increase in furrow length in the metaphase of cycle 12. There is a decrease in cell shape index in metaphase from cycles 11 to 13. This coincides with Drosophila E-cad (DE-cadherin) and Bazooka enrichment at the edges and the septin, Peanut at the vertices of the furrow. We further assess the role of polarity and adhesion proteins in pseudocleavage furrow formation and its organization as a polygonal array. We find that DE-cadherin depletion leads to decreased furrow length, loss of hexagon dominance, and increased cell shape index. Bazooka and Peanut depletion lead to decreased furrow length, delay in onset of hexagon dominance from cycle 12 to 13, and increased cell shape index. Hexagon dominance occurs with an increase in furrow length in cycle 13 and increased DE-cadherin, possibly due to the inhibition of endocytosis. We conclude that polarity protein recruitment and regulation of endocytic pathways enable pseudocleavage furrow stability and the formation of a hexagon-dominated polygon array.
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Affiliation(s)
- Bipasha Dey
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Debasmita Mitra
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Tirthasree Das
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Aparna Sherlekar
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Ramya Balaji
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune 411008, India
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3
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Miao H, Millage M, Rollins KR, Blankenship JT. A Rab39-Klp98A-Rab35 endocytic recycling pathway is essential for rapid Golgi-dependent furrow ingression. Development 2023; 150:dev201547. [PMID: 37590130 PMCID: PMC10445802 DOI: 10.1242/dev.201547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 07/18/2023] [Indexed: 08/19/2023]
Abstract
Ingression of the plasma membrane is an essential part of the cell topology-distorting repertoire and a key element in animal cell cytokinesis. Many embryos have rapid cleavage stages in which they are furrowing powerhouses, quickly forming and disassembling cleavage furrows on timescales of just minutes. Previous work has shown that cytoskeletal proteins and membrane trafficking coordinate to drive furrow ingression, but where these membrane stores are derived from and how they are directed to furrowing processes has been less clear. Here, we identify an extensive Rab35/Rab4>Rab39/Klp98A>trans-Golgi network (TGN) endocytic recycling pathway necessary for fast furrow ingression in the Drosophila embryo. Rab39 is present in vesiculotubular compartments at the TGN where it receives endocytically derived cargo through a Rab35/Rab4-dependent pathway. A Kinesin-3 family member, Klp98A, drives the movements and tubulation activities of Rab39, and disruption of this Rab39-Klp98A-Rab35 pathway causes deep furrow ingression defects and genomic instability. These data suggest that an endocytic recycling pathway rapidly remobilizes membrane cargo from the cell surface and directs it to the trans-Golgi network to permit the initiation of new cycles of cleavage furrow formation.
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Affiliation(s)
- Hui Miao
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Megan Millage
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | | | - J. Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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4
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Yeh AR, Hoeprich GJ, Goode BL, Martin AC. Bitesize bundles F-actin and influences actin remodeling in syncytial Drosophila embryo development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.17.537198. [PMID: 37131807 PMCID: PMC10153138 DOI: 10.1101/2023.04.17.537198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Actin networks undergo rearrangements that influence cell and tissue shape. Actin network assembly and organization is regulated in space and time by a host of actin binding proteins. The Drosophila Synaptotagmin-like protein, Bitesize (Btsz), is known to organize actin at epithelial cell apical junctions in a manner that depends on its interaction with the actin-binding protein, Moesin. Here, we showed that Btsz functions in actin reorganization at earlier, syncytial stages of Drosophila embryo development. Btsz was required for the formation of stable metaphase pseudocleavage furrows that prevented spindle collisions and nuclear fallout prior to cellularization. While previous studies focused on Btsz isoforms containing the Moesin Binding Domain (MBD), we found that isoforms lacking the MBD also function in actin remodeling. Consistent with this, we found that the C-terminal half of BtszB cooperatively binds to and bundles F-actin, suggesting a direct mechanism for Synaptotagmin-like proteins regulating actin organization during animal development.
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5
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de-Carvalho J, Tlili S, Hufnagel L, Saunders TE, Telley IA. Aster repulsion drives short-ranged ordering in the Drosophila syncytial blastoderm. Development 2022; 149:274085. [DOI: 10.1242/dev.199997] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 12/17/2021] [Indexed: 12/28/2022]
Abstract
ABSTRACT
Biological systems are highly complex, yet notably ordered structures can emerge. During syncytial stage development of the Drosophila melanogaster embryo, nuclei synchronously divide for nine cycles within a single cell, after which most of the nuclei reach the cell cortex. The arrival of nuclei at the cortex occurs with remarkable positional order, which is important for subsequent cellularisation and morphological transformations. Yet, the mechanical principles underlying this lattice-like positional order of nuclei remain untested. Here, using quantification of nuclei position and division orientation together with embryo explants, we show that short-ranged repulsive interactions between microtubule asters ensure the regular distribution and maintenance of nuclear positions in the embryo. Such ordered nuclear positioning still occurs with the loss of actin caps and even the loss of the nuclei themselves; the asters can self-organise with similar distribution to nuclei in the wild-type embryo. The explant assay enabled us to deduce the nature of the mechanical interaction between pairs of nuclei. We used this to predict how the nuclear division axis orientation changes upon nucleus removal from the embryo cortex, which we confirmed in vivo with laser ablation. Overall, we show that short-ranged microtubule-mediated repulsive interactions between asters are important for ordering in the early Drosophila embryo and minimising positional irregularity.
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Affiliation(s)
- Jorge de-Carvalho
- Physics of Intracellular Organization Group, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | - Sham Tlili
- Mechanobiology Institute, National University of Singapore, 117411 Singapore
| | - Lars Hufnagel
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Timothy E. Saunders
- Mechanobiology Institute, National University of Singapore, 117411 Singapore
- Department of Biological Sciences, National University of Singapore, 117411Singapore
- Institute of Molecular and Cellular Biology, A*Star, Proteos, 138632 Singapore
- Warwick Medical School, University of Warwick, Coventry, CV4 7HL, UK
| | - Ivo A. Telley
- Physics of Intracellular Organization Group, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
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6
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Xie Y, Budhathoki R, Blankenship JT. Combinatorial deployment of F-actin regulators to build complex 3D actin structures in vivo. eLife 2021; 10:63046. [PMID: 33949307 PMCID: PMC8149123 DOI: 10.7554/elife.63046] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 05/04/2021] [Indexed: 02/05/2023] Open
Abstract
Despite extensive studies on the actin regulators that direct microfilament dynamics, how these regulators are combinatorially utilized in organismal tissues to generate 3D structures is an unresolved question. Here, we present an in-depth characterization of cortical actin cap dynamics and their regulation in vivo. We identify rapid phases of initiation, expansion, duplication, and disassembly and examine the functions of seven different actin and/or nucleator regulators (ANRPs) in guiding these behaviors. We find ANRPs provide distinct activities in building actin cap morphologies – specifically, while DPod1 is a major regulator of actin intensities, Cortactin is required for continued cortical growth, while Coronin functions in both growth and intensity and is required for Cortactin localization to the cap periphery. Unexpectedly, cortical actin populations recover more rapidly after regulator disruption, suggestive of a deep competition for limited G-actin pools, and we measure in vivo Arp2/3 recruitment efficiencies through an ectopic relocalization strategy. Our results illustrate how the coordination of multiple actin regulators can orchestrate organized and dynamic actin structures in a developmental system.
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Affiliation(s)
- Yi Xie
- Department of Biological Sciences, University of Denver, Denver, United States
| | - Rashmi Budhathoki
- Department of Biological Sciences, University of Denver, Denver, United States
| | - J Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, United States
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7
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Yatsenko AS, Kucherenko MM, Xie Y, Urlaub H, Shcherbata HR. Exocyst-mediated membrane trafficking of the lissencephaly-associated ECM receptor dystroglycan is required for proper brain compartmentalization. eLife 2021; 10:63868. [PMID: 33620318 PMCID: PMC7929561 DOI: 10.7554/elife.63868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 02/23/2021] [Indexed: 12/14/2022] Open
Abstract
To assemble a brain, differentiating neurons must make proper connections and establish specialized brain compartments. Abnormal levels of cell adhesion molecules disrupt these processes. Dystroglycan (Dg) is a major non-integrin cell adhesion receptor, deregulation of which is associated with dramatic neuroanatomical defects such as lissencephaly type II or cobblestone brain. The previously established Drosophila model for cobblestone lissencephaly was used to understand how Dg is regulated in the brain. During development, Dg has a spatiotemporally dynamic expression pattern, fine-tuning of which is crucial for accurate brain assembly. In addition, mass spectrometry analyses identified numerous components associated with Dg in neurons, including several proteins of the exocyst complex. Data show that exocyst-based membrane trafficking of Dg allows its distinct expression pattern, essential for proper brain morphogenesis. Further studies of the Dg neuronal interactome will allow identification of new factors involved in the development of dystroglycanopathies and advance disease diagnostics in humans.
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Affiliation(s)
- Andriy S Yatsenko
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Mariya M Kucherenko
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Yuanbin Xie
- Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Research Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,University Medical Center Göttingen, Bioanalytics, Institute for Clinical Chemistry, Göttingen, Germany
| | - Halyna R Shcherbata
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany.,Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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8
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Lv Z, de-Carvalho J, Telley IA, Großhans J. Cytoskeletal mechanics and dynamics in the Drosophila syncytial embryo. J Cell Sci 2021; 134:134/4/jcs246496. [PMID: 33597155 DOI: 10.1242/jcs.246496] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cell and tissue functions rely on the genetic programmes and cascades of biochemical signals. It has become evident during the past decade that the physical properties of soft material that govern the mechanics of cells and tissues play an important role in cellular function and morphology. The biophysical properties of cells and tissues are determined by the cytoskeleton, consisting of dynamic networks of F-actin and microtubules, molecular motors, crosslinkers and other associated proteins, among other factors such as cell-cell interactions. The Drosophila syncytial embryo represents a simple pseudo-tissue, with its nuclei orderly embedded in a structured cytoskeletal matrix at the embryonic cortex with no physical separation by cellular membranes. Here, we review the stereotypic dynamics and regulation of the cytoskeleton in Drosophila syncytial embryos and how cytoskeletal dynamics underlies biophysical properties and the emergence of collective features. We highlight the specific features and processes of syncytial embryos and discuss the applicability of biophysical approaches.
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Affiliation(s)
- Zhiyi Lv
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, 266003, China
| | - Jorge de-Carvalho
- Instituto Gulbenkian de Ciência, Fundação Calouste Gulbenkian, 2780-156 Oeiras, Portugal
| | - Ivo A Telley
- Instituto Gulbenkian de Ciência, Fundação Calouste Gulbenkian, 2780-156 Oeiras, Portugal
| | - Jörg Großhans
- Fachbereich Biologie, Philipps-Universität Marburg, 35043 Marburg, Germany
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9
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de la Riva-Carrasco R, Perez-Pandolfo S, Suárez Freire S, Romero NM, Bhujabal Z, Johansen T, Wappner P, Melani M. The immunophilin Zonda controls regulated exocytosis in endocrine and exocrine tissues. Traffic 2021; 22:111-122. [PMID: 33336828 DOI: 10.1111/tra.12777] [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: 06/28/2020] [Revised: 12/15/2020] [Accepted: 12/15/2020] [Indexed: 11/30/2022]
Abstract
Exocytosis is a fundamental process in physiology, that ensures communication between cells, organs and even organisms. Hormones, neuropeptides and antibodies, among other cargoes are packed in exocytic vesicles that need to reach and fuse with the plasma membrane to release their content to the extracellular milieu. Hundreds of proteins participate in this process and several others in its regulation. We report here a novel component of the exocytic machinery, the Drosophila transmembrane immunophilin Zonda (Zda), previously found to participate in autophagy. Zda is highly expressed in secretory tissues, and regulates exocytosis in at least three of them: the ring gland, insulin-producing cells and the salivary gland. Using the salivary gland as a model system, we found that Zda is required at final steps of the exocytic process for fusion of secretory granules to the plasma membrane. In a genetic screen we identified the small GTPase RalA as a crucial regulator of secretory granule exocytosis that is required, similarly to Zda, for fusion between the secretory granule and the plasma membrane.
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Affiliation(s)
| | - Sebastián Perez-Pandolfo
- Laboratorio de Genética y Fisiología Molecular, Fundación Instituto Leloir, Buenos Aires, Argentina
| | - Sofía Suárez Freire
- Laboratorio de Genética y Fisiología Molecular, Fundación Instituto Leloir, Buenos Aires, Argentina
| | - Nuria M Romero
- Université Côte d'Azur, INRA, CNRS, Institut Sophia Agrobiotech, Sophia Antipolis, France
| | - Zambarlal Bhujabal
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Terje Johansen
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Pablo Wappner
- Laboratorio de Genética y Fisiología Molecular, Fundación Instituto Leloir, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mariana Melani
- Laboratorio de Genética y Fisiología Molecular, Fundación Instituto Leloir, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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10
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Dey B, Rikhy R. DE-cadherin and Myosin II balance regulates furrow length for onset of polygon shape in syncytial Drosophila embryos. J Cell Sci 2020; 133:jcs240168. [PMID: 32265269 DOI: 10.1242/jcs.240168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 03/26/2020] [Indexed: 08/31/2023] Open
Abstract
Cell shape morphogenesis, from spherical to polygonal, occurs in epithelial cell formation in metazoan embryogenesis. In syncytial Drosophila embryos, the plasma membrane incompletely surrounds each nucleus and is organized as a polygonal epithelial-like array. Each cortical syncytial division cycle shows a circular to polygonal plasma membrane transition along with furrow extension between adjacent nuclei from interphase to metaphase. In this study, we assess the relative contribution of DE-cadherin (also known as Shotgun) and Myosin II (comprising Zipper and Spaghetti squash in flies) at the furrow to polygonal shape transition. We show that polygonality initiates during each cortical syncytial division cycle when the furrow extends from 4.75 to 5.75 μm. Polygon plasma membrane organization correlates with increased junctional tension, increased DE-cadherin and decreased Myosin II mobility. DE-cadherin regulates furrow length and polygonality. Decreased Myosin II activity allows for polygonality to occur at a lower length than controls. Increased Myosin II activity leads to loss of lateral furrow formation and complete disruption of the polygonal shape transition. Our studies show that DE-cadherin-Myosin II balance regulates an optimal lateral membrane length during each syncytial cycle for polygonal shape transition.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Bipasha Dey
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Homi Bhabha Road, Pashan, Pune, 411008, India
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11
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Nakamura Y, Ochi Y, Satoh T, Satoh AK. Rab10, Crag and Ehbp1 regulate the basolateral transport of Na +K +ATPase in Drosophila photoreceptors. J Cell Sci 2020; 133:jcs238790. [PMID: 32041903 DOI: 10.1242/jcs.238790] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/27/2020] [Indexed: 08/31/2023] Open
Abstract
Cells in situ are often polarized and have multiple plasma membrane domains. To establish and maintain these domains, polarized transport is essential, and its impairment results in genetic disorders. Nevertheless, the underlying mechanisms of polarized transport have not been elucidated. Drosophila photoreceptor offers an excellent model for studying this. We found that Rab10 impairment significantly reduced basolateral levels of Na+K+ATPase, mislocalizing it to the stalk membrane, which is a domain of the apical plasma membrane. Furthermore, the shrunken basolateral and the expanded stalk membranes were accompanied with abnormalities in the Golgi cisternae of Rab10-impaired retinas. The deficiencies of Rab10-GEF Crag or the Rab10 effector Ehbp1 phenocopied Rab10 deficiency, indicating that Crag, Rab10 and Ehbp1 work together for polarized trafficking of membrane proteins to the basolateral membrane. These phenotypes were similar to those seen upon deficiency of AP1 or clathrin, which are known to be involved in the basolateral transport in other systems. Additionally, Crag, Rab10 and Ehbp1 colocalized with AP1 and clathrin on the trans-side of Golgi stacks. Taken together, these results indicate that AP1 and clathrin, and Crag, Rab10 and Ehbp1 collaborate in polarized basolateral transport, presumably in the budding process in the trans-Golgi network.
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Affiliation(s)
- Yuri Nakamura
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Yuka Ochi
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Takunori Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akiko K Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
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12
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Silva-Rodrigues JF, Patrício-Rodrigues CF, de Sousa-Xavier V, Augusto PM, Fernandes AC, Farinho AR, Martins JP, Teodoro RO. Peripheral axonal ensheathment is regulated by RalA GTPase and the exocyst complex. Development 2020; 147:dev.174540. [PMID: 31969325 DOI: 10.1242/dev.174540] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/14/2020] [Indexed: 12/21/2022]
Abstract
Axon ensheathment is fundamental for fast impulse conduction and the normal physiological functioning of the nervous system. Defects in axonal insulation lead to debilitating conditions, but, despite its importance, the molecular players responsible are poorly defined. Here, we identify RalA GTPase as a key player in axon ensheathment in Drosophila larval peripheral nerves. We demonstrate through genetic analysis that RalA action through the exocyst complex is required in wrapping glial cells to regulate their growth and development. We suggest that the RalA-exocyst pathway controls the targeting of secretory vesicles for membrane growth or for the secretion of a wrapping glia-derived factor that itself regulates growth. In summary, our findings provide a new molecular understanding of the process by which axons are ensheathed in vivo, a process that is crucial for normal neuronal function.
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Affiliation(s)
- Joana F Silva-Rodrigues
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Cátia F Patrício-Rodrigues
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Vicente de Sousa-Xavier
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Pedro M Augusto
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Ana C Fernandes
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - Ana R Farinho
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
| | - João P Martins
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal.,Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Rita O Teodoro
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School - Faculdade de Ciências Médicas, Universidade Nova de Lisboa, 1150-082 Lisboa, Portugal
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13
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Jiang T, Harris TJC. Par-1 controls the composition and growth of cortical actin caps during Drosophila embryo cleavage. J Cell Biol 2019; 218:4195-4214. [PMID: 31641019 PMCID: PMC6891076 DOI: 10.1083/jcb.201903152] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 08/21/2019] [Accepted: 09/22/2019] [Indexed: 11/22/2022] Open
Abstract
The cell cortex is populated by various proteins, but it is unclear how they interact to change cell shape. Jiang and Harris find that the kinase Par-1 is required for Diaphanous-based actin bundles, and that these bundles intersperse with separately induced Arp2/3 networks to form an actin cap that grows into a metaphase compartment of the syncytial Drosophila embryo. Cell structure depends on the cortex, a thin network of actin polymers and additional proteins underlying the plasma membrane. The cell polarity kinase Par-1 is required for cells to form following syncytial Drosophila embryo development. This requirement stems from Par-1 promoting cortical actin caps that grow into dome-like metaphase compartments for dividing syncytial nuclei. We find the actin caps to be a composite material of Diaphanous (Dia)-based actin bundles interspersed with independently formed, Arp2/3-based actin puncta. Par-1 and Dia colocalize along extended regions of the bundles, and both are required for the bundles and for each other’s bundle-like localization, consistent with an actin-dependent self-reinforcement mechanism. Par-1 helps establish or maintain these bundles in a cortical domain with relatively low levels of the canonical formin activator Rho1-GTP. Arp2/3 is required for displacing the bundles away from each other and toward the cap circumference, suggesting interactions between these cytoskeletal components could contribute to the growth of the cap into a metaphase compartment.
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Affiliation(s)
- Tao Jiang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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14
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Patrício-Rodrigues C, Teodoro R. Postsynaptic Rab GTPases and Exocyst: a screen at the Drosophila neuromuscular junction. ACTA ACUST UNITED AC 2018. [DOI: 10.19185/matters.201807000005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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15
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Zhang Y, Yu JC, Jiang T, Fernandez-Gonzalez R, Harris TJC. Collision of Expanding Actin Caps with Actomyosin Borders for Cortical Bending and Mitotic Rounding in a Syncytium. Dev Cell 2018; 45:551-564.e4. [PMID: 29804877 DOI: 10.1016/j.devcel.2018.04.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 03/30/2018] [Accepted: 04/25/2018] [Indexed: 10/24/2022]
Abstract
The early Drosophila embryo is a large syncytial cell that compartmentalizes mitotic spindles with furrows. Before furrow ingression, an Arp2/3 actin cap forms above each nucleus and is encircled by actomyosin. We investigated how these networks transform a flat cortex into a honeycomb-like compartmental array. The growing caps circularize and ingress upon meeting their actomyosin borders, which become the furrow base. Genetic perturbations indicate that the caps physically displace their borders and, reciprocally, that the borders resist and circularize their caps. These interactions create an actomyosin cortex arrayed with circular caps. The Rac-GEF Sponge, Rac-GTP, Arp3, and actin coat the caps as a growing material that can drive cortical bending for initial furrow ingression. Additionally, laser ablations indicate that actomyosin contraction squeezes the cytoplasm, producing counterforces that swell the caps. Thus, Arp2/3 caps form clearances of the actomyosin cortex and control buckling and swelling of these clearances for metaphase compartmentalization.
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Affiliation(s)
- Yixie Zhang
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Jessica C Yu
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Tao Jiang
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Rodrigo Fernandez-Gonzalez
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5G 1M1, Canada; Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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16
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Abstract
Cells depend on hugely diverse lipidomes for many functions. The actions and structural integrity of the plasma membrane and most organelles also critically depend on membranes and their lipid components. Despite the biological importance of lipids, our understanding of lipid engagement, especially the roles of lipid hydrophobic alkyl side chains, in key cellular processes is still developing. Emerging research has begun to dissect the importance of lipids in intricate events such as cell division. This review discusses how these structurally diverse biomolecules are spatially and temporally regulated during cell division, with a focus on cytokinesis. We analyze how lipids facilitate changes in cellular morphology during division and how they participate in key signaling events. We identify which cytokinesis proteins are associated with membranes, suggesting lipid interactions. More broadly, we highlight key unaddressed questions in lipid cell biology and techniques, including mass spectrometry, advanced imaging, and chemical biology, which will help us gain insights into the functional roles of lipids.
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Affiliation(s)
- Elisabeth M Storck
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, United Kingdom;
| | - Cagakan Özbalci
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, United Kingdom;
| | - Ulrike S Eggert
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, United Kingdom; .,Department of Chemistry, King's College London, London SE1 1DB, United Kingdom
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17
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Xie Y, Blankenship JT. Differentially-dimensioned furrow formation by zygotic gene expression and the MBT. PLoS Genet 2018; 14:e1007174. [PMID: 29337989 PMCID: PMC5786337 DOI: 10.1371/journal.pgen.1007174] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 01/26/2018] [Accepted: 12/29/2017] [Indexed: 12/17/2022] Open
Abstract
Despite extensive work on the mechanisms that generate plasma membrane furrows, understanding how cells are able to dynamically regulate furrow dimensions is an unresolved question. Here, we present an in-depth characterization of furrow behaviors and their regulation in vivo during early Drosophila morphogenesis. We show that the deepening in furrow dimensions with successive nuclear cycles is largely due to the introduction of a new, rapid ingression phase (Ingression II). Blocking the midblastula transition (MBT) by suppressing zygotic transcription through pharmacological or genetic means causes the absence of Ingression II, and consequently reduces furrow dimensions. The analysis of compound chromosomes that produce chromosomal aneuploidies suggests that multiple loci on the X, II, and III chromosomes contribute to the production of differentially-dimensioned furrows, and we track the X-chromosomal contribution to furrow lengthening to the nullo gene product. We further show that checkpoint proteins are required for furrow lengthening; however, mitotic phases of the cell cycle are not strictly deterministic for furrow dimensions, as a decoupling of mitotic phases with periods of active ingression occurs as syncytial furrow cycles progress. Finally, we examined the turnover of maternal gene products and find that this is a minor contributor to the developmental regulation of furrow morphologies. Our results suggest that cellularization dynamics during cycle 14 are a continuation of dynamics established during the syncytial cycles and provide a more nuanced view of developmental- and MBT-driven morphogenesis. One of the primary events that must occur repeatedly throughout a complex animal’s lifetime is the ingression of a plasma membrane furrow. Furrow formation and ingression are requisite elements of cell division, and drive the physical separation of one cell into two cells. However, the mechanisms that permit an embryo to change the length and size of a furrow are unclear. Here, we show that a combination of higher ingression rates and longer duration phases drive changes in furrow dimensions through the introduction of a new ingression phase. These changes are driven by the embryo’s own genome, and suggest that zygotic transcription controls organismal form at an earlier time point than previously appreciated. Additionally, the failure to properly lengthen furrows as development proceeds causes defects in chromosome segregation during cell division and results in massive genomic instability. Our data demonstrate the importance of the dynamic regulation of furrow dimensions to organismal form and viability.
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Affiliation(s)
- Yi Xie
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
| | - J. Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO, United States of America
- * E-mail:
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18
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Richhariya S, Hasan G. Ral function in muscle is required for flight maintenance in Drosophila. Small GTPases 2017; 11:174-179. [PMID: 29284321 PMCID: PMC7549642 DOI: 10.1080/21541248.2017.1367456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ral is a small GTPase of the Ras superfamily that is important for a number of cellular functions. Recently, we found that expression of Ral is regulated by store-operated calcium entry (SOCE) in Drosophila neurons. In this study, through genetic and behavioural experiments, we show that Ral function is required in differentiated muscles for flight. Reducing Ral function in muscles, specifically reduced duration of flight bouts but not other motor functions, like climbing. Interestingly, unlike in the nervous system, Ral expression in the muscle is not regulated by SOCE. Moreover, either knockdown or genetic inhibition of SOCE in muscles does not affect flight. These findings demonstrate that a multiplicity of signalling mechanisms very likely regulate Ral expression in different tissues.
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Affiliation(s)
- Shlesha Richhariya
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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19
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Analysis of mitochondrial organization and function in the Drosophila blastoderm embryo. Sci Rep 2017; 7:5502. [PMID: 28710464 PMCID: PMC5511145 DOI: 10.1038/s41598-017-05679-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 06/01/2017] [Indexed: 11/25/2022] Open
Abstract
Mitochondria are inherited maternally as globular and immature organelles in metazoan embryos. We have used the Drosophila blastoderm embryo to characterize their morphology, distribution and functions in embryogenesis. We find that mitochondria are relatively small, dispersed and distinctly distributed along the apico-basal axis in proximity to microtubules by motor protein transport. Live imaging, photobleaching and photoactivation analyses of mitochondrially targeted GFP show that they are mobile in the apico-basal axis along microtubules and are immobile in the lateral plane thereby associating with one syncytial cell. Photoactivated mitochondria distribute equally to daughter cells across the division cycles. ATP depletion by pharmacological and genetic inhibition of the mitochondrial electron transport chain (ETC) activates AMPK and decreases syncytial metaphase furrow extension. In summary, we show that small and dispersed mitochondria of the Drosophila blastoderm embryo localize by microtubule transport and provide ATP locally for the fast syncytial division cycles. Our study opens the possibility of use of Drosophila embryogenesis as a model system to study the impact of maternal mutations in mitochondrial morphology and metabolism on embryo patterning and differentiation.
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20
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Rodrigues FF, Harris TJC. Key roles of Arf small G proteins and biosynthetic trafficking for animal development. Small GTPases 2017; 10:403-410. [PMID: 28410007 DOI: 10.1080/21541248.2017.1304854] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Although biosynthetic trafficking can function constitutively, it also functions specifically for certain developmental processes. These processes require either a large increase to biosynthesis or the biosynthesis and targeted trafficking of specific players. We review the conserved molecular mechanisms that direct biosynthetic trafficking, and discuss how their genetic disruption affects animal development. Specifically, we consider Arf small G proteins, such as Arf1 and Sar1, and their coat effectors, COPI and COPII, and how these proteins promote biosynthetic trafficking for cleavage of the Drosophila embryo, the growth of neuronal dendrites and synapses, extracellular matrix secretion for bone development, lumen development in epithelial tubes, notochord and neural tube development, and ciliogenesis. Specific need for the biosynthetic trafficking system is also evident from conserved CrebA/Creb3-like transcription factors increasing the expression of secretory machinery during several of these developmental processes. Moreover, dysfunctional trafficking leads to a range of developmental syndromes.
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Affiliation(s)
- Francisco F Rodrigues
- Department of Cell & Systems Biology, University of Toronto , Toronto , Ontario , Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto , Toronto , Ontario , Canada
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21
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Abstract
BAR domain proteins can regulate ‘membrane reservoirs’ that provide surface area and buffer membrane tension. Syndapin is an F-BAR and SH3 domain containing protein involved in cytoskeletal remodelling and endocytosis. The Syndapin F-BAR domain is uniquely versatile compared to others in the family and can bend phospholipid membranes into tubules of various diameters and directly bind actin. The Syndapin SH3 domain can also interact with actin remodelling proteins and modulate cytoskeletal contractility. Pseudocleavage furrow extension in the syncytial division cycles of Drosophila embryos requires the homeostatic control of conserved processes that control plasma membrane tension and actin contractility. We find that Syndapin plays an important role in promoting pseudocleavage furrow extension. We propose a model involving roles for Syndapin in membrane dynamics and direct or indirect effect on the cytoskeleton to explain how it affects pseudocleavage furrow growth, independent of its role in endocytosis.
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Affiliation(s)
- Aparna Sherlekar
- Biology, Indian Institute of Science Education and Research, Pune, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Pune, India
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22
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Rodrigues FF, Shao W, Harris TJC. The Arf GAP Asap promotes Arf1 function at the Golgi for cleavage furrow biosynthesis in Drosophila. Mol Biol Cell 2016; 27:3143-3155. [PMID: 27535433 PMCID: PMC5063621 DOI: 10.1091/mbc.e16-05-0272] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/11/2016] [Indexed: 11/11/2022] Open
Abstract
Drosophila embryo cleavage requires the conserved Arf GAP Asap. Asap seems to recycle Arf1 to the Golgi from post-Golgi membranes for optimal Golgi output and cleavage furrow biosynthesis. Biosynthetic traffic from the Golgi drives plasma membrane growth. For Drosophila embryo cleavage, this growth is rapid but regulated for cycles of furrow ingression and regression. The highly conserved small G protein Arf1 organizes Golgi trafficking. Arf1 is activated by guanine nucleotide exchange factors, but essential roles for Arf1 GTPase-activating proteins (GAPs) are less clear. We report that the conserved Arf GAP Asap is required for cleavage furrow ingression in the early embryo. Because Asap can affect multiple subcellular processes, we used genetic approaches to dissect its primary effect. Our data argue against cytoskeletal or endocytic involvement and reveal a common role for Asap and Arf1 in Golgi organization. Although Asap lacked Golgi enrichment, it was necessary and sufficient for Arf1 accumulation at the Golgi, and a conserved Arf1-Asap binding site was required for Golgi organization and output. Of note, Asap relocalized to the nuclear region at metaphase, a shift that coincided with subtle Golgi reorganization preceding cleavage furrow regression. We conclude that Asap is essential for Arf1 to function at the Golgi for cleavage furrow biosynthesis. Asap may recycle Arf1 to the Golgi from post-Golgi membranes, providing optimal Golgi output for specific stages of the cell cycle.
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Affiliation(s)
- Francisco F Rodrigues
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Wei Shao
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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23
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Sherlekar A, Rikhy R. Syndapin promotes pseudocleavage furrow formation by actin organization in the syncytial Drosophila embryo. Mol Biol Cell 2016; 27:2064-79. [PMID: 27146115 PMCID: PMC4927280 DOI: 10.1091/mbc.e15-09-0656] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 04/26/2016] [Indexed: 12/03/2022] Open
Abstract
F-BAR domain–containing proteins link the actin cytoskeleton to the membrane during membrane remodeling. Syndapin associates with the pseudocleavage furrow membrane and is essential for furrow morphology, actin organization, and extension downstream of initiation factor RhoGEF2. Coordinated membrane and cytoskeletal remodeling activities are required for membrane extension in processes such as cytokinesis and syncytial nuclear division cycles in Drosophila. Pseudocleavage furrow membranes in the syncytial Drosophila blastoderm embryo show rapid extension and retraction regulated by actin-remodeling proteins. The F-BAR domain protein Syndapin (Synd) is involved in membrane tubulation, endocytosis, and, uniquely, in F-actin stability. Here we report a role for Synd in actin-regulated pseudocleavage furrow formation. Synd localized to these furrows, and its loss resulted in short, disorganized furrows. Synd presence was important for the recruitment of the septin Peanut and distribution of Diaphanous and F-actin at furrows. Synd and Peanut were both absent in furrow-initiation mutants of RhoGEF2 and Diaphanous and in furrow-progression mutants of Anillin. Synd overexpression in rhogef2 mutants reversed its furrow-extension phenotypes, Peanut and Diaphanous recruitment, and F-actin organization. We conclude that Synd plays an important role in pseudocleavage furrow extension, and this role is also likely to be crucial in cleavage furrow formation during cell division.
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Affiliation(s)
- Aparna Sherlekar
- Biology, Indian Institute of Science Education and Research, Pashan, Pune 411008, India
| | - Richa Rikhy
- Biology, Indian Institute of Science Education and Research, Pashan, Pune 411008, India
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24
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Mavor LM, Miao H, Zuo Z, Holly RM, Xie Y, Loerke D, Blankenship JT. Rab8 directs furrow ingression and membrane addition during epithelial formation in Drosophila melanogaster. Development 2016; 143:892-903. [PMID: 26839362 PMCID: PMC4813336 DOI: 10.1242/dev.128876] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/25/2016] [Indexed: 01/31/2023]
Abstract
One of the most fundamental changes in cell morphology is the ingression of a plasma membrane furrow. The Drosophila embryo undergoes several cycles of rapid furrow ingression during early development that culminate in the formation of an epithelial sheet. Previous studies have demonstrated the requirement for intracellular trafficking pathways in furrow ingression; however, the pathways that link compartmental behaviors with cortical furrow ingression events are unclear. Here, we show that Rab8 has striking dynamic behaviors in vivo. As furrows ingress, cytoplasmic Rab8 puncta are depleted and Rab8 accumulates at the plasma membrane in a location that coincides with known regions of directed membrane addition. We additionally use CRISPR/Cas9 technology to N-terminally tag Rab8, which is then used to address endogenous localization and function. Endogenous Rab8 displays partial coincidence with Rab11 and the Golgi, and this colocalization is enriched during the fast phase of cellularization. When Rab8 function is disrupted, furrow formation in the early embryo is completely abolished. We also demonstrate that Rab8 behaviors require the function of the exocyst complex subunit Sec5 as well as the recycling endosome protein Rab11. Active, GTP-locked Rab8 is primarily associated with dynamic membrane compartments and the plasma membrane, whereas GDP-locked Rab8 forms large cytoplasmic aggregates. These studies suggest a model in which active Rab8 populations direct furrow ingression by guiding the targeted delivery of cytoplasmic membrane stores to the cell surface through interactions with the exocyst tethering complex.
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Affiliation(s)
- Lauren M Mavor
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Hui Miao
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Zhongyuan Zuo
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Ryan M Holly
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Yi Xie
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Dinah Loerke
- Department of Physics, University of Denver, Denver, CO 80208, USA
| | - J Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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25
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Holly RM, Mavor LM, Zuo Z, Blankenship JT. A rapid, membrane-dependent pathway directs furrow formation through RalA in the early Drosophila embryo. J Cell Sci 2015. [DOI: 10.1242/jcs.176560] [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] Open
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