1
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Lehne F, Bogdan S. Swip-1 promotes exocytosis of glue granules in the exocrine Drosophila salivary gland. J Cell Sci 2023; 136:286884. [PMID: 36727484 PMCID: PMC10038153 DOI: 10.1242/jcs.260366] [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: 06/22/2022] [Accepted: 01/27/2023] [Indexed: 02/03/2023] Open
Abstract
Exocytosis is a fundamental cellular process by which cells secrete cargos from their apical membrane into the extracellular lumen. Cargo release proceeds in sequential steps that depend on coordinated assembly and organization of an actin cytoskeletal network. Here, we identified the conserved actin-crosslinking protein Swip-1 as a novel regulator controlling exocytosis of glue granules in the Drosophila salivary gland. Real-time imaging revealed that Swip-1 is simultaneously recruited with F-actin onto secreting granules in proximity to the apical membrane. We observed that Swip-1 is rapidly cleared at the point of secretory vesicle fusion and colocalizes with actomyosin network around the fused vesicles. Loss of Swip-1 function impairs secretory cargo expulsion, resulting in strongly delayed secretion. Thus, our results uncover a novel role of Swip-1 in secretory vesicle compression and expulsion of cargo during regulated exocytosis. Remarkably, this function neither requires Ca2+ binding nor dimerization of Swip-1. Our data rather suggest that Swip-1 regulates actomyosin activity upstream of Rho-GTPase signaling to drive proper vesicle membrane crumpling and expulsion of cargo.
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Affiliation(s)
- Franziska Lehne
- Institute of Physiology and Pathophysiology, Department of Molecular Cell Physiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Sven Bogdan
- Institute of Physiology and Pathophysiology, Department of Molecular Cell Physiology, Philipps-University Marburg, 35037 Marburg, Germany
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2
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Drosophila melanogaster: A Model System to Study Distinct Genetic Programs in Myoblast Fusion. Cells 2022; 11:cells11030321. [PMID: 35159130 PMCID: PMC8834112 DOI: 10.3390/cells11030321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 11/25/2022] Open
Abstract
Muscle fibers are multinucleated cells that arise during embryogenesis through the fusion of mononucleated myoblasts. Myoblast fusion is a lifelong process that is crucial for the growth and regeneration of muscles. Understanding the molecular mechanism of myoblast fusion may open the way for novel therapies in muscle wasting and weakness. Recent reports in Drosophila and mammals have provided new mechanistic insights into myoblast fusion. In Drosophila, muscle formation occurs twice: during embryogenesis and metamorphosis. A fundamental feature is the formation of a cell–cell communication structure that brings the apposing membranes into close proximity and recruits possible fusogenic proteins. However, genetic studies suggest that myoblast fusion in Drosophila is not a uniform process. The complexity of the players involved in myoblast fusion can be modulated depending on the type of muscle that is formed. In this review, we introduce the different types of multinucleated muscles that form during Drosophila development and provide an overview in advances that have been made to understand the mechanism of myoblast fusion. Finally, we will discuss conceptual frameworks in cell–cell fusion in Drosophila and mammals.
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Abstract
Cell-cell fusion is indispensable for creating life and building syncytial tissues and organs. Ever since the discovery of cell-cell fusion, how cells join together to form zygotes and multinucleated syncytia has remained a fundamental question in cell and developmental biology. In the past two decades, Drosophila myoblast fusion has been used as a powerful genetic model to unravel mechanisms underlying cell-cell fusion in vivo. Many evolutionarily conserved fusion-promoting factors have been identified and so has a surprising and conserved cellular mechanism. In this review, we revisit key findings in Drosophila myoblast fusion and highlight the critical roles of cellular invasion and resistance in driving cell membrane fusion.
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Affiliation(s)
- Donghoon M Lee
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA;
| | - Elizabeth H Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA;
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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4
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RNAi Screen in Tribolium Reveals Involvement of F-BAR Proteins in Myoblast Fusion and Visceral Muscle Morphogenesis in Insects. G3-GENES GENOMES GENETICS 2019; 9:1141-1151. [PMID: 30733382 PMCID: PMC6469413 DOI: 10.1534/g3.118.200996] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In a large-scale RNAi screen in Tribolium castaneum for genes with knock-down phenotypes in the larval somatic musculature, one recurring phenotype was the appearance of larval muscle fibers that were significantly thinner than those in control animals. Several of the genes producing this knock-down phenotype corresponded to orthologs of Drosophila genes that are known to participate in myoblast fusion, particularly via their effects on actin polymerization. A new gene previously not implicated in myoblast fusion but displaying a similar thin-muscle knock-down phenotype was the Tribolium ortholog of Nostrin, which encodes an F-BAR and SH3 domain protein. Our genetic studies of Nostrin and Cip4, a gene encoding a structurally related protein, in Drosophila show that the encoded F-BAR proteins jointly contribute to efficient myoblast fusion during larval muscle development. Together with the F-Bar protein Syndapin they are also required for normal embryonic midgut morphogenesis. In addition, Cip4 is required together with Nostrin during the profound remodeling of the midgut visceral musculature during metamorphosis. We propose that these F-Bar proteins help govern proper morphogenesis particularly of the longitudinal midgut muscles during metamorphosis.
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5
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Rüder M, Nagel BM, Bogdan S. Analysis of Cell Shape and Cell Migration of Drosophila Macrophages In Vivo. Methods Mol Biol 2018; 1749:227-238. [PMID: 29526001 DOI: 10.1007/978-1-4939-7701-7_17] [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: 03/18/2023]
Abstract
The most abundant immune cells in Drosophila are macrophage-like plasmatocytes that fulfill central roles in morphogenesis, immune and tissue damage response. The various genetic tools available in Drosophila together with high-resolution and live-imaging microscopy techniques make Drosophila macrophages an excellent model system that combines many advantages of cultured cells with in vivo genetics. Here, we describe the isolation and staining of macrophages from larvae for ex vivo structured illumination microscopy (SIM), the preparation of white prepupae for in vivo 2D random cell migration analysis, and the preparation of pupae (18 h after puparium formation, APF) for in vivo 3D directed cell migration analysis upon wounding using spinning disk microscopy.
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Affiliation(s)
- Marike Rüder
- Institut für Physiologie und Pathophysiologie, Abteilung Molekulare Zellphysiologie, Phillips-Universität Marburg, Marburg, Germany
| | - Benedikt M Nagel
- Institut für Physiologie und Pathophysiologie, Abteilung Molekulare Zellphysiologie, Phillips-Universität Marburg, Marburg, Germany
| | - Sven Bogdan
- Institut für Physiologie und Pathophysiologie, Abteilung Molekulare Zellphysiologie, Phillips-Universität Marburg, Marburg, Germany.
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6
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Deng S, Azevedo M, Baylies M. Acting on identity: Myoblast fusion and the formation of the syncytial muscle fiber. Semin Cell Dev Biol 2017; 72:45-55. [PMID: 29101004 DOI: 10.1016/j.semcdb.2017.10.033] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/25/2017] [Accepted: 10/30/2017] [Indexed: 12/25/2022]
Abstract
The study of Drosophila muscle development dates back to the middle of the last century. Since that time, Drosophila has proved to be an ideal system for studying muscle development, differentiation, function, and disease. As in humans, Drosophila muscle forms via a series of conserved steps, starting with muscle specification, myoblast fusion, attachment to tendon cells, interactions with motorneurons, and sarcomere and myofibril formation. The genes and mechanisms required for these processes share striking similarities to those found in humans. The highly tractable genetic system and imaging approaches available in Drosophila allow for an efficient interrogation of muscle biology and for application of what we learn to other systems. In this article, we review our current understanding of muscle development in Drosophila, with a focus on myoblast fusion, the process responsible for the generation of syncytial muscle cells. We also compare and contrast those genes required for fusion in Drosophila and vertebrates.
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Affiliation(s)
- Su Deng
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY 10065, United States
| | - Mafalda Azevedo
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY 10065, United States; Graduate Program in Basic and Applied Biology (GABBA), Institute of Biomedical Sciences Abel Salazar, University of Porto, Porto, Portugal
| | - Mary Baylies
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY 10065, United States.
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Abstract
Proteins of the Wiskott-Aldrich syndrome protein (WASP) family function as nucleation-promoting factors for the ubiquitously expressed Arp2/3 complex, which drives the generation of branched actin filaments. Arp2/3-generated actin regulates diverse cellular processes, including the formation of lamellipodia and filopodia, endocytosis and/or phagocytosis at the plasma membrane, and the generation of cargo-laden vesicles from organelles including the Golgi, endoplasmic reticulum (ER) and the endo-lysosomal network. Recent studies have also identified roles for WASP family members in promoting actin dynamics at the centrosome, influencing nuclear shape and membrane remodeling events leading to the generation of autophagosomes. Interestingly, several WASP family members have also been observed in the nucleus where they directly influence gene expression by serving as molecular platforms for the assembly of epigenetic and transcriptional machinery. In this Cell Science at a Glance article and accompanying poster, we provide an update on the subcellular roles of WHAMM, JMY and WASH (also known as WASHC1), as well as their mechanisms of regulation and emerging functions within the cell.
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Affiliation(s)
- Olga Alekhina
- Division of Oncology Research, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Ezra Burstein
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX 75390-9151, USA.,Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390-9151, USA
| | - Daniel D Billadeau
- Division of Oncology Research, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA .,Department of Biochemistry and Molecular Biology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.,Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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8
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Nagel BM, Bechtold M, Rodriguez LG, Bogdan S. Drosophila WASH is required for integrin-mediated cell adhesion, cell motility and lysosomal neutralization. J Cell Sci 2016; 130:344-359. [PMID: 27884932 DOI: 10.1242/jcs.193086] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/08/2016] [Indexed: 12/14/2022] Open
Abstract
The Wiskott-Aldrich syndrome protein and SCAR homolog (WASH; also known as Washout in flies) is a conserved actin-nucleation-promoting factor controlling Arp2/3 complex activity in endosomal sorting and recycling. Previous studies have identified WASH as an essential regulator in Drosophila development. Here, we show that homozygous wash mutant flies are viable and fertile. We demonstrate that Drosophila WASH has conserved functions in integrin receptor recycling and lysosome neutralization. WASH generates actin patches on endosomes and lysosomes, thereby mediating both aforementioned functions. Consistently, loss of WASH function results in cell spreading and cell migration defects of macrophages, and an increased lysosomal acidification that affects efficient phagocytic and autophagic clearance. WASH physically interacts with the vacuolar (V)-ATPase subunit Vha55 that is crucial to establish and maintain lysosome acidification. As a consequence, starved flies that lack WASH function show a dramatic increase in acidic autolysosomes, causing a reduced lifespan. Thus, our data highlight a conserved role for WASH in the endocytic sorting and recycling of membrane proteins, such as integrins and the V-ATPase, that increase the likelihood of survival under nutrient deprivation.
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Affiliation(s)
- Benedikt M Nagel
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.,Institut für Physiologie und Pathophysiologie, Abteilung Molekulare Zellphysiologie, Phillips-Universität Marburg, Emil-Mannkopff-Straße 2, 35037 Marburg, Germany
| | - Meike Bechtold
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | | | - Sven Bogdan
- Institut für Neurobiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany .,Institut für Physiologie und Pathophysiologie, Abteilung Molekulare Zellphysiologie, Phillips-Universität Marburg, Emil-Mannkopff-Straße 2, 35037 Marburg, Germany
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9
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Tyler JJ, Allwood EG, Ayscough KR. WASP family proteins, more than Arp2/3 activators. Biochem Soc Trans 2016; 44:1339-1345. [PMID: 27911716 PMCID: PMC5095904 DOI: 10.1042/bst20160176] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 07/14/2016] [Accepted: 07/21/2016] [Indexed: 01/19/2023]
Abstract
Wiskott-Aldrich syndrome protein (WASP) family proteins have been extensively characterized as factors that promote the nucleation of actin through the activation of the protein complex Arp2/3. While yeast mostly have a single member of the family, mammalian cells have at least six different members, often with multiple isoforms. Members of the family are characterized by a common structure. Their N-termini are varied and are considered to confer spatial and temporal regulation of Arp2/3-activating activity, whereas their C-terminal half contains a polyproline-rich region, one or more WASP homology-2 (WH2) actin-binding domains and motifs that bind directly to Arp2/3. Recent studies, however, indicate that the yeast WASP homologue Las17 is able to nucleate actin independently of Arp2/3 through the function of novel G-actin-binding activities in its polyproline region. This allows Las17 to generate the mother filaments that are needed for subsequent Arp2/3 recruitment and activation during the actin polymerization that drives endocytic invagination in yeast. In this review, we consider how motifs within the polyproline region of Las17 support nucleation of actin filaments, and whether similar mechanisms might exist among other family members.
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Affiliation(s)
- Joe J Tyler
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield S10 2TN, U.K
| | - Ellen G Allwood
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield S10 2TN, U.K
| | - Kathryn R Ayscough
- Department of Biomedical Science, Firth Court, University of Sheffield, Sheffield S10 2TN, U.K
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10
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Brüser L, Bogdan S. Molecular Control of Actin Dynamics In Vivo: Insights from Drosophila. Handb Exp Pharmacol 2016; 235:285-310. [PMID: 27757759 DOI: 10.1007/164_2016_33] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The actin cytoskeleton provides mechanical support for cells and generates forces to drive cell shape changes and cell migration in morphogenesis. Molecular understanding of actin dynamics requires a genetically traceable model system that allows interdisciplinary experimental approaches to elucidate the regulatory network of cytoskeletal proteins in vivo. Here, we will discuss some examples of how advances in Drosophila genetics and high-resolution imaging techniques contribute to the discovery of new actin functions, signaling pathways, and mechanisms of actin regulation in vivo.
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Affiliation(s)
- Lena Brüser
- Institute for Neurobiology, University of Muenster, Badestrasse 9, 48149, Muenster, Germany
| | - Sven Bogdan
- Institute for Neurobiology, University of Muenster, Badestrasse 9, 48149, Muenster, Germany.
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