1
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Guo Y, Hartson SD, Rogers J, Brooks-Kanost L, Brooks D, Geisbrecht ER. Protocol for affinity purification-mass spectrometry interactome profiling in larvae of Drosophila melanogaster. STAR Protoc 2024; 5:103064. [PMID: 38743568 PMCID: PMC11108999 DOI: 10.1016/j.xpro.2024.103064] [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] [Received: 03/20/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/16/2024] Open
Abstract
Many techniques exist for the identification of protein interaction networks. We present a protocol that relies on an affinity purification-mass spectrometry (AP-MS) approach to detect proteins that co-purify with a tagged bait of interest from Drosophila melanogaster larval muscles using the GAL4/upstream activating sequence (UAS) expression system. We also describe steps for the isolation and identification of protein complexes, followed by streamlined bioinformatics analysis for rapid and reproducible results. This protocol can be extended to investigate protein interactions in other tissues. For complete details on the use and execution of this protocol, please refer to Guo et al.1.
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Affiliation(s)
- Yungui Guo
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66503, USA.
| | - Steven D Hartson
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Janet Rogers
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Lillian Brooks-Kanost
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66503, USA
| | - David Brooks
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66503, USA.
| | - Erika R Geisbrecht
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66503, USA.
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2
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Chen J, Li G, He X, Chen X, Chen Z, Liu D, Guo S, Huang T, Lin Y, Lan P, Lian L, He X. ELMO1 ameliorates intestinal epithelial cellular senescence via SIRT1/p65 signaling in inflammatory bowel disease-related fibrosis. Gastroenterol Rep (Oxf) 2024; 12:goae045. [PMID: 38756351 PMCID: PMC11096966 DOI: 10.1093/gastro/goae045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/01/2024] [Accepted: 04/10/2024] [Indexed: 05/18/2024] Open
Abstract
Background Intestinal fibrosis is a common complication in inflammatory bowel disease (IBD), which still lacks of reliable markers and therapeutic options. Cellular senescence has been considered an important mechanism of intestinal fibrosis, but the underlying molecular link remains elusive. Methods Tissues were stained using α-smooth muscle actin (α-SMA), fibronectin, and collagen I as markers of myofibroblastic differentiation. Cellular senescence was confirmed through Lamin B1 staining, senescence-associated β-galactosidase staining, and the expression of senescence-associated secretory phenotype (SASP) factors. We explored the relationship between senescence of intestinal epithelial cells (IECs) and intestinal fibrosis, as well as the molecular mechanism underlying this interaction. The effects of irisin on cellular senescence and fibrosis were determined. Results Here, we identify engulfment and cell motility protein 1 (ELMO1) as a novel biomarker for intestinal cellular senescence and fibrosis. In fibrostrictured tissues from patients and murine models with IBD, significantly high levels of cellular senescence score and factors were noted, which positively correlated with the fibrotic regulator fibronectin. Senescent IECs, not fibroblast itself, released SASP factors to regulate fibroblast activation. Prolonging exposure to severe and persistent injurious stimuli decreased ELMO1 expression, which dampened SIRT1 deacetylase activity, enhanced NF-κB (p65) acetylation, and thereby accelerated cellular senescence. Deletion of ELMO1 led to senescent IECs accumulation and triggered premature fibrosis in murine colitis. Furthermore, irisin, inhibiting the degradation of ELMO1, could downregulate p65 acetylation, reduce IECs senescence, and prevent incipient intestinal fibrosis in murine colitis models. Conclusions This study reveals ELMO1 downregulation is an early symbol of intestinal senescence and fibrosis, and the altered ELMO1-SIRT1-p65 pathway plays an important role in intestinal cellular senescence and IBD-related fibrosis.
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Affiliation(s)
- Junguo Chen
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Department of Thoracic Surgery, Thoracic Cancer Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Guanman Li
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- School of Medicine (Shenzhen), Sun Yat-sen University, Shenzhen, Guangdong, P. R. China
| | - Xiaowen He
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Xijie Chen
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Department of Gastrointestinal Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Zexian Chen
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Danling Liu
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Shuang Guo
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Tianze Huang
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Yanyun Lin
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Ping Lan
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Lei Lian
- Department of Gastrointestinal Surgery, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Xiaosheng He
- Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital,Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
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3
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Whitlock JM. Muscle Progenitor Cell Fusion in the Maintenance of Skeletal Muscle. Results Probl Cell Differ 2024; 71:257-279. [PMID: 37996682 DOI: 10.1007/978-3-031-37936-9_13] [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
Skeletal muscle possesses a resident, multipotent stem cell population that is essential for its repair and maintenance throughout life. Here I highlight the role of this stem cell population in muscle repair and regeneration and review the genetic control of the process; the mechanistic steps of activation, migration, recognition, adhesion, and fusion of these cells; and discuss the novel recognition of the membrane signaling that coordinates myogenic cell-cell fusion, as well as the identification of a two-part fusogen system that facilitates it.
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Affiliation(s)
- Jarred M Whitlock
- Section on Membrane Biology, Eunice Kennedy Shrive National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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4
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Morioka S, Kajioka D, Yamaoka Y, Ellison RM, Tufan T, Werkman IL, Tanaka S, Barron B, Ito ST, Kucenas S, Okusa MD, Ravichandran KS. Chimeric efferocytic receptors improve apoptotic cell clearance and alleviate inflammation. Cell 2022; 185:4887-4903.e17. [PMID: 36563662 PMCID: PMC9930200 DOI: 10.1016/j.cell.2022.11.029] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 10/03/2022] [Accepted: 11/24/2022] [Indexed: 12/24/2022]
Abstract
Our bodies turn over billions of cells daily via apoptosis and are in turn cleared by phagocytes via the process of "efferocytosis." Defects in efferocytosis are now linked to various inflammatory diseases. Here, we designed a strategy to boost efferocytosis, denoted "chimeric receptor for efferocytosis" (CHEF). We fused a specific signaling domain within the cytoplasmic adapter protein ELMO1 to the extracellular phosphatidylserine recognition domains of the efferocytic receptors BAI1 or TIM4, generating BELMO and TELMO, respectively. CHEF-expressing phagocytes display a striking increase in efferocytosis. In mouse models of inflammation, BELMO expression attenuates colitis, hepatotoxicity, and nephrotoxicity. In mechanistic studies, BELMO increases ER-resident enzymes and chaperones to overcome protein-folding-associated toxicity, which was further validated in a model of ER-stress-induced renal ischemia-reperfusion injury. Finally, TELMO introduction after onset of kidney injury significantly reduced fibrosis. Collectively, these data advance a concept of chimeric efferocytic receptors to boost efferocytosis and dampen inflammation.
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Affiliation(s)
- Sho Morioka
- The Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA; Department of Medicine, Division of Nephrology and Center for Immunity, Inflammation and Regenerative Medicine (CIIR), University of Virginia, Charlottesville, VA, USA; Preemptive Food Research Center (PFRC), Gifu University Institute for Advanced Study, Gifu, Japan.
| | - Daiki Kajioka
- Department of Medicine, Division of Nephrology and Center for Immunity, Inflammation and Regenerative Medicine (CIIR), University of Virginia, Charlottesville, VA, USA
| | - Yusuke Yamaoka
- Department of Medicine, Division of Nephrology and Center for Immunity, Inflammation and Regenerative Medicine (CIIR), University of Virginia, Charlottesville, VA, USA; Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Rochelle M Ellison
- Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - Turan Tufan
- The Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA; Department of Computational Biology and Medical Science, Graduate School of Frontier Science, University of Tokyo, Tokyo, Japan
| | - Inge L Werkman
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Shinji Tanaka
- Department of Medicine, Division of Nephrology and Center for Immunity, Inflammation and Regenerative Medicine (CIIR), University of Virginia, Charlottesville, VA, USA
| | - Brady Barron
- The Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA; Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA
| | - Satoshi T Ito
- Department of Medicine, Division of Nephrology and Center for Immunity, Inflammation and Regenerative Medicine (CIIR), University of Virginia, Charlottesville, VA, USA; Department of Computational Biology and Medical Science, Graduate School of Frontier Science, University of Tokyo, Tokyo, Japan
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Mark D Okusa
- Department of Medicine, Division of Nephrology and Center for Immunity, Inflammation and Regenerative Medicine (CIIR), University of Virginia, Charlottesville, VA, USA
| | - Kodi S Ravichandran
- The Center for Cell Clearance, University of Virginia, Charlottesville, VA, USA; Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA; VIB/UGent Inflammation Research Centre, Biomedical Molecular Biology, Ghent University, Ghent, Belgium; Division of Immunobiology, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA.
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5
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Tran V, Nahlé S, Robert A, Desanlis I, Killoran R, Ehresmann S, Thibault MP, Barford D, Ravichandran KS, Sauvageau M, Smith MJ, Kmita M, Côté JF. Biasing the conformation of ELMO2 reveals that myoblast fusion can be exploited to improve muscle regeneration. Nat Commun 2022; 13:7077. [PMID: 36400788 PMCID: PMC9674853 DOI: 10.1038/s41467-022-34806-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 11/08/2022] [Indexed: 11/21/2022] Open
Abstract
Myoblast fusion is fundamental for the development of multinucleated myofibers. Evolutionarily conserved proteins required for myoblast fusion include RAC1 and its activator DOCK1. In the current study we analyzed the contribution of the DOCK1-interacting ELMO scaffold proteins to myoblast fusion. When Elmo1-/- mice underwent muscle-specific Elmo2 genetic ablation, they exhibited severe myoblast fusion defects. A mutation in the Elmo2 gene that reduced signaling resulted in a decrease in myoblast fusion. Conversely, a mutation in Elmo2 coding for a protein with an open conformation increased myoblast fusion during development and in muscle regeneration. Finally, we showed that the dystrophic features of the Dysferlin-null mice, a model of limb-girdle muscular dystrophy type 2B, were reversed when expressing ELMO2 in an open conformation. These data provide direct evidence that the myoblast fusion process could be exploited for regenerative purposes and improve the outcome of muscle diseases.
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Affiliation(s)
- Viviane Tran
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Sarah Nahlé
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC, H3T 1J4, Canada
| | - Amélie Robert
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
| | - Inès Desanlis
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Department of Medicine, Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Ryan Killoran
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, QC, H3T 1J4, Canada
| | - Sophie Ehresmann
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC, H3T 1J4, Canada
| | | | - David Barford
- MRC Laboratory of Molecular Biology, Cambridge, CB2 OQH, UK
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, 22908, VA, USA
- VIB/UGent Inflammation Research Centre, Biomedical Molecular Biology, Ghent University, 9052, Ghent, Belgium
| | - Martin Sauvageau
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, QC, H3C 3J7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC, H3T 1J4, Canada
- Department of Biochemistry, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Matthew J Smith
- Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, QC, H3T 1J4, Canada
- Department of Pathology and Cell Biology, Université de Montréal, Montreal, QC, H3C 3J7, Canada
| | - Marie Kmita
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC, H3T 1J4, Canada
- Department of Medicine, Université de Montréal, Montreal, QC, H3C 3J7, Canada
- Department of Experimental Medicine, McGill University, Montréal, QC, H3G 2M1, Canada
| | - Jean-François Côté
- Montreal Clinical Research Institute (IRCM), Montreal, QC, H2W 1R7, Canada.
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, QC, H3C 3J7, Canada.
- Molecular Biology Programs, Université de Montréal, Montréal, QC, H3T 1J4, Canada.
- Department of Medicine, Université de Montréal, Montreal, QC, H3C 3J7, Canada.
- Department of Anatomy and Cell Biology, McGill University, Montréal, QC, H3A 0C7, Canada.
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6
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Actin Up: An Overview of the Rac GEF Dock1/Dock180 and Its Role in Cytoskeleton Rearrangement. Cells 2022; 11:cells11223565. [PMID: 36428994 PMCID: PMC9688060 DOI: 10.3390/cells11223565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/27/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
Dock1, originally Dock180, was the first identified member of the Dock family of GTPase Exchange Factors. Early biochemical and genetic studies of Dock180 elucidated the functions and regulation of Dock180 and informed our understanding of all Dock family members. Dock180 activates Rac to stimulate actin polymerization in response to signals initiated by a variety of receptors. Dock180 dependent Rac activation is essential for processes such as apoptotic cell engulfment, myoblast fusion, and cell migration during development and homeostasis. Inappropriate Dock180 activity has been implicated in cancer invasion and metastasis and in the uptake of bacterial pathogens. Here, we give an overview of the history and current understanding of the activity, regulation, and impacts of Dock180.
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7
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Sponge/DOCK-dependent regulation of F-actin networks directing cortical cap behaviors and syncytial furrow ingression. Dev Biol 2022; 491:82-93. [PMID: 36067836 DOI: 10.1016/j.ydbio.2022.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 08/03/2022] [Accepted: 08/17/2022] [Indexed: 11/22/2022]
Abstract
In the early syncytial Drosophila embryo, rapid changes in filamentous actin networks and membrane trafficking pathways drive the formation and remodeling of cortical and furrow morphologies. Interestingly, genomic integrity and the completion of mitoses during cell cycles 10-13 depends on the formation of transient membrane furrows that serve to separate and anchor individual spindles during division. While substantial work has led to a better understanding of the core network components that are responsible for the formation of these furrows, less is known about the regulation that controls cytoskeletal and trafficking function. The DOCK protein Sponge was one of the first proteins identified as being required for syncytial furrow formation, and disruption of Sponge deeply compromises F-actin populations in the early embryo, but how this occurs is less clear. Here, we perform quantitative analysis of the effects of Sponge disruption on cortical cap growth, furrow formation, membrane trafficking, and cytoskeletal network regulation through live-imaging of the syncytial embryo. We find that membrane trafficking is relatively unaffected by the defects in branched actin networks that occur after Sponge disruption, but that Sponge acts as a master regulator of a diverse cohort of Arp2/3 regulatory proteins. As DOCK family proteins have been implicated in regulating GTP exchange on small GTPases, we also suggest that Rac GTPase activity bridges Sponge regulation to the regulators of Arp2/3 function. Finally, we demonstrate the phasic requirements for branched F-actin and linear F-actin networks in potentiating furrow ingression. In total, these results provide quantitative insights into how a large DOCK scaffolding protein coordinates the activity of a variety of different actin regulatory proteins to direct the remodeling of the apical cortex into cytokinetic-like furrows.
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8
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Boger M, Bennewitz K, Wohlfart DP, Hausser I, Sticht C, Poschet G, Kroll J. Comparative Morphological, Metabolic and Transcriptome Analyses in elmo1−/−, elmo2−/−, and elmo3−/− Zebrafish Mutants Identified a Functional Non-Redundancy of the Elmo Proteins. Front Cell Dev Biol 2022; 10:918529. [PMID: 35874819 PMCID: PMC9304559 DOI: 10.3389/fcell.2022.918529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
The ELMO protein family consists of the homologues ELMO1, ELMO2 and ELMO3. Several studies have shown that the individual ELMO proteins are involved in a variety of cellular and developmental processes. However, it has poorly been understood whether the Elmo proteins show similar functions and act redundantly. To address this question, elmo1−/−, elmo2−/− and elmo3−/− zebrafish were generated and a comprehensive comparison of the phenotypic changes in organ morphology, transcriptome and metabolome was performed in these mutants. The results showed decreased fasting and increased postprandial blood glucose levels in adult elmo1−/−, as well as a decreased vascular formation in the adult retina in elmo1−/−, but an increased vascular formation in the adult elmo3−/− retina. The phenotypical comparison provided few similarities, as increased Bowman space areas in adult elmo1−/− and elmo2−/− kidneys, an increased hyaloid vessel diameter in elmo1−/− and elmo3−/− and a transcriptional downregulation of the vascular development in elmo1−/−, elmo2−/−, and elmo3−/− zebrafish larvae. Besides this, elmo1−/−, elmo2−/−, and elmo3−/− zebrafish exhibited several distinct changes in the vascular and glomerular structure and in the metabolome and the transcriptome. Especially, elmo3−/− zebrafish showed extensive differences in the larval transcriptome and an impaired survivability. Together, the data demonstrated that the three zebrafish Elmo proteins regulate not only similar but also divergent biological processes and mechanisms and show a low functional redundancy.
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Affiliation(s)
- Mike Boger
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Katrin Bennewitz
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - David Philipp Wohlfart
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Ingrid Hausser
- Institute of Pathology IPH, EM Lab, Heidelberg University Hospital, Heidelberg, Germany
| | - Carsten Sticht
- NGS Core Facility, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Gernot Poschet
- Metabolomics Core Technology Platform, Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
| | - Jens Kroll
- Department of Vascular Biology and Tumor Angiogenesis, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- *Correspondence: Jens Kroll,
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9
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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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10
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Dillard C, Reis JGT, Rusten TE. RasV12; scrib-/- Tumors: A Cooperative Oncogenesis Model Fueled by Tumor/Host Interactions. Int J Mol Sci 2021; 22:ijms22168873. [PMID: 34445578 PMCID: PMC8396170 DOI: 10.3390/ijms22168873] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/12/2021] [Accepted: 08/12/2021] [Indexed: 12/19/2022] Open
Abstract
The phenomenon of how oncogenes and tumor-suppressor mutations can synergize to promote tumor fitness and cancer progression can be studied in relatively simple animal model systems such as Drosophila melanogaster. Almost two decades after the landmark discovery of cooperative oncogenesis between oncogenic RasV12 and the loss of the tumor suppressor scribble in flies, this and other tumor models have provided new concepts and findings in cancer biology that has remarkable parallels and relevance to human cancer. Here we review findings using the RasV12; scrib-/- tumor model and how it has contributed to our understanding of how these initial simple genetic insults cooperate within the tumor cell to set in motion the malignant transformation program leading to tumor growth through cell growth, cell survival and proliferation, dismantling of cell-cell interactions, degradation of basement membrane and spreading to other organs. Recent findings have demonstrated that cooperativity goes beyond cell intrinsic mechanisms as the tumor interacts with the immediate cells of the microenvironment, the immune system and systemic organs to eventually facilitate malignant progression.
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Affiliation(s)
- Caroline Dillard
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, 0372 Oslo, Norway;
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0379 Oslo, Norway
- Correspondence: (C.D.); (T.E.R.)
| | - José Gerardo Teles Reis
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, 0372 Oslo, Norway;
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0379 Oslo, Norway
| | - Tor Erik Rusten
- Centre for Cancer Cell Reprogramming, Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, 0372 Oslo, Norway;
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, 0379 Oslo, Norway
- Correspondence: (C.D.); (T.E.R.)
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11
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Vita DJ, Meier CJ, Broadie K. Neuronal fragile X mental retardation protein activates glial insulin receptor mediated PDF-Tri neuron developmental clearance. Nat Commun 2021; 12:1160. [PMID: 33608547 PMCID: PMC7896095 DOI: 10.1038/s41467-021-21429-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/08/2021] [Indexed: 01/31/2023] Open
Abstract
Glia engulf and phagocytose neurons during neural circuit developmental remodeling. Disrupting this pruning process contributes to Fragile X syndrome (FXS), a leading cause of intellectual disability and autism spectrum disorder in mammals. Utilizing a Drosophila FXS model central brain circuit, we identify two glial classes responsible for Draper-dependent elimination of developmentally transient PDF-Tri neurons. We find that neuronal Fragile X Mental Retardation Protein (FMRP) drives insulin receptor activation in glia, promotes glial Draper engulfment receptor expression, and negatively regulates membrane-molding ESCRT-III Shrub function during PDF-Tri neuron clearance during neurodevelopment in Drosophila. In this context, we demonstrate genetic interactions between FMRP and insulin receptor signaling, FMRP and Draper, and FMRP and Shrub in PDF-Tri neuron elimination. We show that FMRP is required within neurons, not glia, for glial engulfment, indicating FMRP-dependent neuron-to-glia signaling mediates neuronal clearance. We conclude neuronal FMRP drives glial insulin receptor activation to facilitate Draper- and Shrub-dependent neuronal clearance during neurodevelopment in Drosophila.
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Affiliation(s)
- Dominic J Vita
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Cole J Meier
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Kendal Broadie
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Kennedy Center for Research on Human Development, Nashville, TN, USA.
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA.
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12
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Rodríguez-Pérez F, Manford AG, Pogson A, Ingersoll AJ, Martínez-González B, Rape M. Ubiquitin-dependent remodeling of the actin cytoskeleton drives cell fusion. Dev Cell 2021; 56:588-601.e9. [PMID: 33609460 DOI: 10.1016/j.devcel.2021.01.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 11/14/2020] [Accepted: 01/24/2021] [Indexed: 12/11/2022]
Abstract
Cell-cell fusion is a frequent and essential event during development, and its dysregulation causes diseases ranging from infertility to muscle weakness. Fusing cells need to repeatedly remodel their plasma membrane through orchestrated formation and disassembly of actin filaments, but how the dynamic reorganization of the cortical actin cytoskeleton is controlled is still poorly understood. Here, we identified a ubiquitin-dependent toggle switch that establishes reversible actin bundling during mammalian cell fusion. We found that EPS8-IRSp53 complexes stabilize cortical actin bundles at sites of cell contact to promote close membrane alignment. EPS8 monoubiquitylation by CUL3KCTD10 displaces EPS8-IRSp53 from membranes and counteracts actin bundling, a dual activity that restricts actin bundling to allow paired cells to progress with fusion. We conclude that cytoskeletal rearrangements during development are precisely controlled by ubiquitylation, raising the possibility of modulating the efficiency of cell-cell fusion for therapeutic benefit.
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Affiliation(s)
- Fernando Rodríguez-Pérez
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Andrew G Manford
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Angela Pogson
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Andrew J Ingersoll
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Brenda Martínez-González
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Michael Rape
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA.
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13
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An insight on Drosophila myogenesis and its assessment techniques. Mol Biol Rep 2020; 47:9849-9863. [PMID: 33263930 DOI: 10.1007/s11033-020-06006-0] [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: 04/10/2020] [Accepted: 11/16/2020] [Indexed: 10/22/2022]
Abstract
Movement assisted by muscles forms the basis of various behavioural traits seen in Drosophila. Myogenesis involves developmental processes like cellular specification, differentiation, migration, fusion, adherence to tendons and neuronal innervation in a series of coordinated event well defined in body space and time. Gene regulatory networks are switched on-off, fine tuning at the right developmental stage to assist each cellular event. Drosophila is a holometabolous organism that undergoes myogenesis waves at two developmental stages, and is ideal for comparative analysis of the role of genes and genetic pathways conserved across phyla. In this review we have summarized myogenic events from the embryo to adult focussing on the somatic muscle development during the early embryonic stage and then on indirect flight muscles (IFM) formation required for adult life, emphasizing on recent trends of analysing muscle mutants and advances in Drosophila muscle biology.
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14
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Lv Z, Rosenbaum J, Mohr S, Zhang X, Kong D, Preiß H, Kruss S, Alim K, Aspelmeier T, Großhans J. The Emergent Yo-yo Movement of Nuclei Driven by Cytoskeletal Remodeling in Pseudo-synchronous Mitotic Cycles. Curr Biol 2020; 30:2564-2573.e5. [DOI: 10.1016/j.cub.2020.04.078] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/25/2020] [Accepted: 04/27/2020] [Indexed: 11/15/2022]
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15
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Brooks D, Naeem F, Stetsiv M, Goetting SC, Bawa S, Green N, Clark C, Bashirullah A, Geisbrecht ER. Drosophila NUAK functions with Starvin/BAG3 in autophagic protein turnover. PLoS Genet 2020; 16:e1008700. [PMID: 32320396 PMCID: PMC7176095 DOI: 10.1371/journal.pgen.1008700] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 02/28/2020] [Indexed: 11/18/2022] Open
Abstract
The inability to remove protein aggregates in post-mitotic cells such as muscles or neurons is a cellular hallmark of aging cells and is a key factor in the initiation and progression of protein misfolding diseases. While protein aggregate disorders share common features, the molecular level events that culminate in abnormal protein accumulation cannot be explained by a single mechanism. Here we show that loss of the serine/threonine kinase NUAK causes cellular degeneration resulting from the incomplete clearance of protein aggregates in Drosophila larval muscles. In NUAK mutant muscles, regions that lack the myofibrillar proteins F-actin and Myosin heavy chain (MHC) instead contain damaged organelles and the accumulation of select proteins, including Filamin (Fil) and CryAB. NUAK biochemically and genetically interacts with Drosophila Starvin (Stv), the ortholog of mammalian Bcl-2-associated athanogene 3 (BAG3). Consistent with a known role for the co-chaperone BAG3 and the Heat shock cognate 71 kDa (HSC70)/HSPA8 ATPase in the autophagic clearance of proteins, RNA interference (RNAi) of Drosophila Stv, Hsc70-4, or autophagy-related 8a (Atg8a) all exhibit muscle degeneration and muscle contraction defects that phenocopy NUAK mutants. We further demonstrate that Fil is a target of NUAK kinase activity and abnormally accumulates upon loss of the BAG3-Hsc70-4 complex. In addition, Ubiquitin (Ub), ref(2)p/p62, and Atg8a are increased in regions of protein aggregation, consistent with a block in autophagy upon loss of NUAK. Collectively, our results establish a novel role for NUAK with the Stv-Hsc70-4 complex in the autophagic clearance of proteins that may eventually lead to treatment options for protein aggregate diseases.
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Affiliation(s)
- David Brooks
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Fawwaz Naeem
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Marta Stetsiv
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Samantha C Goetting
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Simranjot Bawa
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Nicole Green
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Cheryl Clark
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
| | - Arash Bashirullah
- Division of Pharmaceutical Sciences, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Erika R Geisbrecht
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States of America
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16
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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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17
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Geisbrecht ER, Baylies MK. In memoriam: Susan Abmayr (1956–2019) – “What do we do? Whatever it takes!”. Skelet Muscle 2019. [PMCID: PMC6882191 DOI: 10.1186/s13395-019-0215-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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18
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Rival CM, Xu W, Shankman LS, Morioka S, Arandjelovic S, Lee CS, Wheeler KM, Smith RP, Haney LB, Isakson BE, Purcell S, Lysiak JJ, Ravichandran KS. Phosphatidylserine on viable sperm and phagocytic machinery in oocytes regulate mammalian fertilization. Nat Commun 2019; 10:4456. [PMID: 31575859 PMCID: PMC6773685 DOI: 10.1038/s41467-019-12406-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/29/2019] [Indexed: 01/06/2023] Open
Abstract
Fertilization is essential for species survival. Although Izumo1 and Juno are critical for initial interaction between gametes, additional molecules necessary for sperm:egg fusion on both the sperm and the oocyte remain to be defined. Here, we show that phosphatidylserine (PtdSer) is exposed on the head region of viable and motile sperm, with PtdSer exposure progressively increasing during sperm transit through the epididymis. Functionally, masking phosphatidylserine on sperm via three different approaches inhibits fertilization. On the oocyte, phosphatidylserine recognition receptors BAI1, CD36, Tim-4, and Mer-TK contribute to fertilization. Further, oocytes lacking the cytoplasmic ELMO1, or functional disruption of RAC1 (both of which signal downstream of BAI1/BAI3), also affect sperm entry into oocytes. Intriguingly, mammalian sperm could fuse with skeletal myoblasts, requiring PtdSer on sperm and BAI1/3, ELMO2, RAC1 in myoblasts. Collectively, these data identify phosphatidylserine on viable sperm and PtdSer recognition receptors on oocytes as key players in sperm:egg fusion.
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Affiliation(s)
- Claudia M Rival
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Urology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Wenhao Xu
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Laura S Shankman
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Sho Morioka
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Sanja Arandjelovic
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Chang Sup Lee
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Gyeongsang National University, 501 Jinju-daero, Jinju, Gyeongnam, 52828, Republic of Korea
| | - Karen M Wheeler
- Department of Urology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Ryan P Smith
- Department of Urology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Lisa B Haney
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Brant E Isakson
- Department of Molecular Physiology and Biological Physics, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA
| | - Scott Purcell
- Reproductive Medicine and Surgery Center of Virginia, 595 Martha Jefferson Dr., Charlottesville, VA, 22911, USA
| | - Jeffrey J Lysiak
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA.
- Department of Urology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA.
| | - Kodi S Ravichandran
- The Center for Cell Clearance, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA.
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall, Charlottesville, VA, 22903, USA.
- Department of Biomedical Molecular Biology, Ghent University, and the UGent-VIB Center for Inflammation Research, Technologiepark 71, 9052, Ghent, Belgium.
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19
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Abstract
Cell-cell fusion is a fundamental process underlying fertilization, development, regeneration and physiology of metazoans. It is a multi-step process involving cell recognition and adhesion, actin cytoskeletal rearrangements, fusogen engagement, lipid mixing and fusion pore formation, ultimately resulting in the integration of two fusion partners. Here, we focus on the asymmetric actin cytoskeletal rearrangements at the site of fusion, known as the fusogenic synapse, which was first discovered during myoblast fusion in Drosophila embryos and later also found in mammalian muscle and non-muscle cells. At the asymmetric fusogenic synapse, actin-propelled invasive membrane protrusions from an attacking fusion partner trigger actomyosin-based mechanosensory responses in the receiving cell. The interplay between the invasive and resisting forces generated by the two fusion partners puts the fusogenic synapse under high mechanical tension and brings the two cell membranes into close proximity, promoting the engagement of fusogens to initiate fusion pore formation. In this Cell Science at a Glance article and the accompanying poster, we highlight the molecular, cellular and biophysical events at the asymmetric fusogenic synapse using Drosophila myoblast fusion as a model.
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Affiliation(s)
- Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Elizabeth H Chen
- Department of Molecular Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA .,Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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20
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Spracklen AJ, Thornton-Kolbe EM, Bonner AN, Florea A, Compton PJ, Fernandez-Gonzalez R, Peifer M. The Crk adapter protein is essential for Drosophila embryogenesis, where it regulates multiple actin-dependent morphogenic events. Mol Biol Cell 2019; 30:2399-2421. [PMID: 31318326 PMCID: PMC6741062 DOI: 10.1091/mbc.e19-05-0302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Small Src homology domain 2 (SH2) and 3 (SH3) adapter proteins regulate cell fate and behavior by mediating interactions between cell surface receptors and downstream signaling effectors in many signal transduction pathways. The CT10 regulator of kinase (Crk) family has tissue-specific roles in phagocytosis, cell migration, and neuronal development and mediates oncogenic signaling in pathways like that of Abelson kinase. However, redundancy among the two mammalian family members and the position of the Drosophila gene on the fourth chromosome precluded assessment of Crk's full role in embryogenesis. We circumvented these limitations with short hairpin RNA and CRISPR technology to assess Crk's function in Drosophila morphogenesis. We found that Crk is essential beginning in the first few hours of development, where it ensures accurate mitosis by regulating orchestrated dynamics of the actin cytoskeleton to keep mitotic spindles in syncytial embryos from colliding. In this role, it positively regulates cortical localization of the actin-related protein 2/3 complex (Arp2/3), its regulator suppressor of cAMP receptor (SCAR), and filamentous actin to actin caps and pseudocleavage furrows. Crk loss leads to the loss of nuclei and formation of multinucleate cells. We also found roles for Crk in embryonic wound healing and in axon patterning in the nervous system, where it localizes to the axons and midline glia. Thus, Crk regulates diverse events in embryogenesis that require orchestrated cytoskeletal dynamics.
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Affiliation(s)
- Andrew J Spracklen
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Emma M Thornton-Kolbe
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Alison N Bonner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Alexandru Florea
- Institute of Biomaterials and Biomedical Engineering, Ted Rogers Centre for Heart Research, and Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Peter J Compton
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Rodrigo Fernandez-Gonzalez
- Institute of Biomaterials and Biomedical Engineering, Ted Rogers Centre for Heart Research, and Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Mark Peifer
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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21
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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: 0.7] [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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22
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Wang JH, Zhao HM, Mo CH, Hou XW. Identification of Differentially Expressed Genes of Rice Under Cadmium Stress Using DDRT-PCR Approach. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 102:589-594. [PMID: 30788561 DOI: 10.1007/s00128-019-02554-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
Cadmium (Cd) is one of the hazardous environmental pollutants, and it can be harmful to human health through consumption of food-plants capable of bioaccumulating Cd. Therefore, lowering cadmium accumulation in plants is highly desirable. Here, a rice cultivar 'Qisanzhan' was studied using differential display reverse transcription-polymerase chain reaction (DDRT-PCR). Fifty-six differentially expressed genes were found in the root tips of 4-leaf stage rice seedlings exposed to 4 and 12 h of 50 µmol/L Cd(NO3)2 in a nutrient solution using DDRT-PCR. Further validation using semi-quantitative RT-PCR showed that the expression patterns of 16 genes were consistent with those found in DDRT-PCR. These genes encode receptor-like protein kinase, pleiotropic drug resistance protein, aquaporin protein, plasma membrane ATPase, etc. The differentially genes identified here can be used to obtain a better understanding of the molecular mechanisms of Cd absorption and accumulation in plants.
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Affiliation(s)
- Jian-Hui Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642, China
| | - Hai-Ming Zhao
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Ce-Hui Mo
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
| | - Xue-Wen Hou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642, China.
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23
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Neumann B, Linton C, Giordano-Santini R, Hilliard MA. Axonal fusion: An alternative and efficient mechanism of nerve repair. Prog Neurobiol 2018; 173:88-101. [PMID: 30500382 DOI: 10.1016/j.pneurobio.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/22/2018] [Accepted: 11/26/2018] [Indexed: 02/07/2023]
Abstract
Injuries to the nervous system can cause lifelong morbidity due to the disconnect that occurs between nerve cells and their cellular targets. Re-establishing these lost connections is the ultimate goal of endogenous regenerative mechanisms, as well as those induced by exogenous manipulations in a laboratory or clinical setting. Reconnection between severed neuronal fibers occurs spontaneously in some invertebrate species and can be induced in mammalian systems. This process, known as axonal fusion, represents a highly efficient means of repair after injury. Recent progress has greatly enhanced our understanding of the molecular control of axonal fusion, demonstrating that the machinery required for the engulfment of apoptotic cells is repurposed to mediate the reconnection between severed axon fragments, which are subsequently merged by fusogen proteins. Here, we review our current understanding of naturally occurring axonal fusion events, as well as those being ectopically produced with the aim of achieving better clinical outcomes.
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Affiliation(s)
- Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne VIC 3800, Australia.
| | - Casey Linton
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rosina Giordano-Santini
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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24
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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: 60] [Impact Index Per Article: 7.5] [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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25
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Schmidt A, Lv Z, Großhans J. ELMO and Sponge specify subapical restriction of Canoe and formation of the subapical domain in early Drosophila embryos. Development 2017; 145:dev.157909. [DOI: 10.1242/dev.157909] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 12/18/2017] [Indexed: 01/06/2023]
Abstract
Canoe/Afadin and the GTPase Rap1 specify the subapical domain during cellularization in Drosophila embryos. The timing of domain formation is unclear. The subapical domain may gradually mature or emerge synchronously with basal and lateral domain. The mechanism for activation of Rap1 by potential guanyl nucleotide exchange factors (GEF) or GTPase activating proteins (GAP) is unknown. Here, we retraced the emergence of the subapical domain at the onset of cellularization by in vivo imaging with CanoeYFP in comparison to the lateral and basal markers, ScribbledGFP and CherrySlam. CanoeYFP accumulates at a subapical position at about the same time as the lateral marker ScribbledGFP but a few minutes prior to basal CherrySlam. Furthermore, we show that the unconventional GEF complex ELMO-Sponge is subapically enriched and is required for subapical restriction of Canoe. The localization dynamics of ELMO-Sponge suggests a patterning mechanism for positioning the subapical region adjacent to the apical region. While marking the disc-like apical regions before cellularization, ELMO-Sponge redistributes to a ring-like pattern surrounding the apical region at the onset of cellularization.
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Affiliation(s)
- Anja Schmidt
- Institute for Developmental Biochemistry, University of Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Zhiyi Lv
- Institute for Developmental Biochemistry, University of Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
| | - Jörg Großhans
- Institute for Developmental Biochemistry, University of Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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Knockdown of ELMO3 Suppresses Growth, Invasion and Metastasis of Colorectal Cancer. Int J Mol Sci 2016; 17:ijms17122119. [PMID: 27999268 PMCID: PMC5187919 DOI: 10.3390/ijms17122119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/05/2016] [Accepted: 12/12/2016] [Indexed: 01/08/2023] Open
Abstract
The engulfment and cell motility (ELMOs) family of proteins plays a crucial role in tumor cell migration and invasion. However, the function of ELMO3 is poorly defined. To elucidate its role in the development and progression of colorectal cancer (CRC), we examined the expression of ELMO3 in 45 cases of paired CRC tumor tissues and adjacent normal tissues. Furthermore, we assessed the effect of the knockdown of ELMO3 on cell proliferation, cell cycle, migration, invasion and F-actin polymerization in HCT116 cells. The result shows that the expression of ELMO3 in CRC tissues was significantly increased in comparison to the adjacent normal colorectal tissues. Moreover, this overexpression was associated with tumor size (p = 0.007), tumor differentiation (p = 0.001), depth of invasion (p = 0.009), lymph node metastasis (p = 0.003), distant metastasis (p = 0.013) and tumor, node, metastasis (TNM)-based classification (p = 0.000). In in vitro experiments, the silencing of ELMO3 inhibited cell proliferation, invasion, metastasis, and F-actin polymerization, and induced Gap 1 (G1) phase cell cycle arrest. Our study demonstrates that ELMO3 is involved in the processes of growth, invasion and metastasis of CRC, and could be used a potential molecular diagnostic tool or therapy target of CRC.
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27
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Schejter ED. Myoblast fusion: Experimental systems and cellular mechanisms. Semin Cell Dev Biol 2016; 60:112-120. [DOI: 10.1016/j.semcdb.2016.07.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 12/18/2022]
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Cetinkaya A, Xiong J, Vargel İ, Kösemehmetoğlu K, Canter H, Gerdan Ö, Longo N, Alzahrani A, Camps M, Taskiran E, Laupheimer S, Botto L, Paramalingam E, Gormez Z, Uz E, Yuksel B, Ruacan Ş, Sağıroğlu M, Takahashi T, Reversade B, Akarsu N. Loss-of-Function Mutations in ELMO2 Cause Intraosseous Vascular Malformation by Impeding RAC1 Signaling. Am J Hum Genet 2016; 99:299-317. [PMID: 27476657 DOI: 10.1016/j.ajhg.2016.06.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 06/09/2016] [Indexed: 12/16/2022] Open
Abstract
Vascular malformations are non-neoplastic expansions of blood vessels that arise due to errors during angiogenesis. They are a heterogeneous group of sporadic or inherited vascular disorders characterized by localized lesions of arteriovenous, capillary, or lymphatic origin. Vascular malformations that occur inside bone tissue are rare. Herein, we report loss-of-function mutations in ELMO2 (which translates extracellular signals into cellular movements) that are causative for autosomal-recessive intraosseous vascular malformation (VMOS) in five different families. Individuals with VMOS suffer from life-threatening progressive expansion of the jaw, craniofacial, and other intramembranous bones caused by malformed blood vessels that lack a mature vascular smooth muscle layer. Analysis of primary fibroblasts from an affected individual showed that absence of ELMO2 correlated with a significant downregulation of binding partner DOCK1, resulting in deficient RAC1-dependent cell migration. Unexpectedly, elmo2-knockout zebrafish appeared phenotypically normal, suggesting that there might be human-specific ELMO2 requirements in bone vasculature homeostasis or genetic compensation by related genes. Comparative phylogenetic analysis indicated that elmo2 originated upon the appearance of intramembranous bones and the jaw in ancestral vertebrates, implying that elmo2 might have been involved in the evolution of these novel traits. The present findings highlight the necessity of ELMO2 for maintaining vascular integrity, specifically in intramembranous bones.
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The Extracellular and Cytoplasmic Domains of Syndecan Cooperate Postsynaptically to Promote Synapse Growth at the Drosophila Neuromuscular Junction. PLoS One 2016; 11:e0151621. [PMID: 26987116 PMCID: PMC4795781 DOI: 10.1371/journal.pone.0151621] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/01/2016] [Indexed: 11/19/2022] Open
Abstract
The heparan sulfate proteoglycan (HSPG) Syndecan (Sdc) is a crucial regulator of synapse development and growth in both vertebrates and invertebrates. In Drosophila, Sdc binds via its extracellular heparan sulfate (HS) sidechains to the receptor protein tyrosine phosphatase LAR to promote the morphological growth of the neuromuscular junction (NMJ). To date, however, little else is known about the molecular mechanisms by which Sdc functions to promote synapse growth. Here we show that all detectable Sdc found at the NMJ is provided by the muscle, strongly suggesting a post-synaptic role for Sdc. We also show that both the cytoplasmic and extracellular domains of Sdc are required to promote synapse growth or to rescue Sdc loss of function. We report the results of a yeast two-hybrid screen using the cytoplasmic domains of Sdc as bait, and identify several novel candidate binding partners for the cytoplasmic domains of Sdc. Together, these studies provide new insight into the mechanism of Sdc function at the NMJ, and provide enticing future directions for further exploring how Sdc promotes synapse growth.
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Park SY, Yun Y, Lim JS, Kim MJ, Kim SY, Kim JE, Kim IS. Stabilin-2 modulates the efficiency of myoblast fusion during myogenic differentiation and muscle regeneration. Nat Commun 2016; 7:10871. [PMID: 26972991 PMCID: PMC4793076 DOI: 10.1038/ncomms10871] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 01/28/2016] [Indexed: 01/16/2023] Open
Abstract
Myoblast fusion is essential for the formation of skeletal muscle myofibres. Studies have shown that phosphatidylserine is necessary for myoblast fusion, but the underlying mechanism is not known. Here we show that the phosphatidylserine receptor stabilin-2 acts as a membrane protein for myoblast fusion during myogenic differentiation and muscle regeneration. Stabilin-2 expression is induced during myogenic differentiation, and is regulated by calcineurin/NFAT signalling in myoblasts. Forced expression of stabilin-2 in myoblasts is associated with increased myotube formation, whereas deficiency of stabilin-2 results in the formation of small, thin myotubes. Stab2-deficient mice have myofibres with small cross-sectional area and few myonuclei and impaired muscle regeneration after injury. Importantly, myoblasts lacking stabilin-2 have reduced phosphatidylserine-dependent fusion. Collectively, our results show that stabilin-2 contributes to phosphatidylserine-dependent myoblast fusion and provide new insights into the molecular mechanism by which phosphatidylserine mediates myoblast fusion during muscle growth and regeneration. Phosphatidylserine and its receptors are associated with cell-cell fusion. Here, the authors show the phosphatidylserine receptor stabilin-2 is expressed by muscle cells and plays a vital role in myoblast fusion and post-injury muscle regeneration in mice.
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Affiliation(s)
- Seung-Yoon Park
- Department of Biochemistry, School of Medicine, Dongguk University, Gyeongju 780-714, Republic of Korea
| | - Youngeun Yun
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu 700-422, Republic of Korea
| | - Jung-Suk Lim
- Department of Biochemistry, School of Medicine, Dongguk University, Gyeongju 780-714, Republic of Korea
| | - Mi-Jin Kim
- Department of Biochemistry, School of Medicine, Dongguk University, Gyeongju 780-714, Republic of Korea
| | - Sang-Yeob Kim
- Department of Convergence Medicine, University of Ulsan, College of Medicine &Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Republic of Korea
| | - Jung-Eun Kim
- Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 700-422, Republic of Korea
| | - In-San Kim
- Biomedical Research Institute, Korea Institute Science and Technology, Seoul 136-791, Republic of Korea.,KU-KIST school, Korea University, Seoul 136-701, Republic of Korea
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Phagocytosis genes nonautonomously promote developmental cell death in the Drosophila ovary. Proc Natl Acad Sci U S A 2016; 113:E1246-55. [PMID: 26884181 DOI: 10.1073/pnas.1522830113] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Programmed cell death (PCD) is usually considered a cell-autonomous suicide program, synonymous with apoptosis. Recent research has revealed that PCD is complex, with at least a dozen cell death modalities. Here, we demonstrate that the large-scale nonapoptotic developmental PCD in the Drosophila ovary occurs by an alternative cell death program where the surrounding follicle cells nonautonomously promote death of the germ line. The phagocytic machinery of the follicle cells, including Draper, cell death abnormality (Ced)-12, and c-Jun N-terminal kinase (JNK), is essential for the death and removal of germ-line-derived nurse cells during late oogenesis. Cell death events including acidification, nuclear envelope permeabilization, and DNA fragmentation of the nurse cells are impaired when phagocytosis is inhibited. Moreover, elimination of a small subset of follicle cells prevents nurse cell death and cytoplasmic dumping. Developmental PCD in the Drosophila ovary is an intriguing example of nonapoptotic, nonautonomous PCD, providing insight on the diversity of cell death mechanisms.
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Dhanyasi N, Segal D, Shimoni E, Shinder V, Shilo BZ, VijayRaghavan K, Schejter ED. Surface apposition and multiple cell contacts promote myoblast fusion in Drosophila flight muscles. J Cell Biol 2016; 211:191-203. [PMID: 26459604 PMCID: PMC4602036 DOI: 10.1083/jcb.201503005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transmission EM methods reveal that cell–cell fusion of individual myoblasts with growing Drosophila flight muscles is a stepwise process in which the cell adhesion and branched actin machineries mediate tight apposition and formation of multiple contacts and pores between the surfaces of the fusing cells. Fusion of individual myoblasts to form multinucleated myofibers constitutes a widely conserved program for growth of the somatic musculature. We have used electron microscopy methods to study this key form of cell–cell fusion during development of the indirect flight muscles (IFMs) of Drosophila melanogaster. We find that IFM myoblast–myotube fusion proceeds in a stepwise fashion and is governed by apparent cross talk between transmembrane and cytoskeletal elements. Our analysis suggests that cell adhesion is necessary for bringing myoblasts to within a minimal distance from the myotubes. The branched actin polymerization machinery acts subsequently to promote tight apposition between the surfaces of the two cell types and formation of multiple sites of cell–cell contact, giving rise to nascent fusion pores whose expansion establishes full cytoplasmic continuity. Given the conserved features of IFM myogenesis, this sequence of cell interactions and membrane events and the mechanistic significance of cell adhesion elements and the actin-based cytoskeleton are likely to represent general principles of the myoblast fusion process.
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Affiliation(s)
- Nagaraju Dhanyasi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India Manipal University, Manipal, Karnataka 576104, India
| | - Dagan Segal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Vera Shinder
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - K VijayRaghavan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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Jiang C, Wang JH, Yue F, Kuang S. The brain expressed x-linked gene 1 (Bex1) regulates myoblast fusion. Dev Biol 2015; 409:16-25. [PMID: 26586200 DOI: 10.1016/j.ydbio.2015.11.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 11/07/2015] [Accepted: 11/11/2015] [Indexed: 11/28/2022]
Abstract
Skeletal muscle development (myogenesis) is a complex but precisely orchestrated process involving spatiotemporal regulation of the proliferation, differentiation and fusion of myogenic progenitor cells (myoblasts). Here we identify brain expressed x-linked gene 1 (Bex1) as a transient, developmentally regulated gene involved in myoblast fusion. Bex1 expression is undetectable in adult muscles or in quiescent muscle stem cells (satellite cells). During embryonic myogenesis, however, Bex1 is robustly expressed by myogenin(+) differentiating myoblasts, but not by Pax7(+) proliferating myoblasts. Interestingly, Bex1 is initially localized in the cytoplasm and then translocates into the nucleus. During adult muscle regeneration, Bex1 is highly expressed in newly regenerated myofibers and the expression is rapidly downregulated during maturation. Consistently, in cultured myoblasts, Bex1 is not expressed at the proliferation stage but transiently expressed upon induction of myogenic differentiation, following a similar cytoplasm to nucleus translocation pattern as seen in vivo. Using gain- and loss-of-function studies, we found that overexpression of Bex1 promotes the fusion of primary myoblasts without affecting myogenic differentiation and myogenin expression. Conversely, Bex1 knockout myoblasts exhibit obvious fusion defects, even though they express normal levels of myogenin and differentiate normally. These results elucidate a novel role of Bex1 in myogenesis through regulating myoblast fusion.
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Affiliation(s)
- Chunhui Jiang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, United States
| | - Jing-Hua Wang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, United States
| | - Feng Yue
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, United States
| | - Shihuan Kuang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, United States; Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States.
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34
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Levy-Strumpf N, Krizus M, Zheng H, Brown L, Culotti JG. The Wnt Frizzled Receptor MOM-5 Regulates the UNC-5 Netrin Receptor through Small GTPase-Dependent Signaling to Determine the Polarity of Migrating Cells. PLoS Genet 2015; 11:e1005446. [PMID: 26292279 PMCID: PMC4546399 DOI: 10.1371/journal.pgen.1005446] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 07/15/2015] [Indexed: 01/28/2023] Open
Abstract
Wnt and Netrin signaling regulate diverse essential functions. Using a genetic approach combined with temporal gene expression analysis, we found a regulatory link between the Wnt receptor MOM-5/Frizzled and the UNC-6/Netrin receptor UNC-5. These two receptors play key roles in guiding cell and axon migrations, including the migration of the C. elegans Distal Tip Cells (DTCs). DTCs migrate post-embryonically in three sequential phases: in the first phase along the Antero-Posterior (A/P) axis, in the second, along the Dorso-Ventral (D/V) axis, and in the third, along the A/P axis. Loss of MOM-5/Frizzled function causes third phase A/P polarity reversals of the migrating DTCs. We show that an over-expression of UNC-5 causes similar DTC A/P polarity reversals and that unc-5 deficits markedly suppress the A/P polarity reversals caused by mutations in mom-5/frizzled. This implicates MOM-5/Frizzled as a negative regulator of unc-5. We provide further evidence that small GTPases mediate MOM-5's regulation of unc-5 such that one outcome of impaired function of small GTPases like CED-10/Rac and MIG-2/RhoG is an increase in unc-5 function. The work presented here demonstrates the existence of cross talk between components of the Netrin and Wnt signaling pathways and provides further insights into the way guidance signaling mechanisms are integrated to orchestrate directed cell migration.
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Affiliation(s)
- Naomi Levy-Strumpf
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- * E-mail:
| | - Meghan Krizus
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Hong Zheng
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Louise Brown
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Joseph G. Culotti
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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Deng S, Bothe I, Baylies MK. The Formin Diaphanous Regulates Myoblast Fusion through Actin Polymerization and Arp2/3 Regulation. PLoS Genet 2015; 11:e1005381. [PMID: 26295716 PMCID: PMC4546610 DOI: 10.1371/journal.pgen.1005381] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 06/23/2015] [Indexed: 11/19/2022] Open
Abstract
The formation of multinucleated muscle cells through cell-cell fusion is a conserved process from fruit flies to humans. Numerous studies have shown the importance of Arp2/3, its regulators, and branched actin for the formation of an actin structure, the F-actin focus, at the fusion site. This F-actin focus forms the core of an invasive podosome-like structure that is required for myoblast fusion. In this study, we find that the formin Diaphanous (Dia), which nucleates and facilitates the elongation of actin filaments, is essential for Drosophila myoblast fusion. Following cell recognition and adhesion, Dia is enriched at the myoblast fusion site, concomitant with, and having the same dynamics as, the F-actin focus. Through analysis of Dia loss-of-function conditions using mutant alleles but particularly a dominant negative Dia transgene, we demonstrate that reduction in Dia activity in myoblasts leads to a fusion block. Significantly, no actin focus is detected, and neither branched actin regulators, SCAR or WASp, accumulate at the fusion site when Dia levels are reduced. Expression of constitutively active Dia also causes a fusion block that is associated with an increase in highly dynamic filopodia, altered actin turnover rates and F-actin distribution, and mislocalization of SCAR and WASp at the fusion site. Together our data indicate that Dia plays two roles during invasive podosome formation at the fusion site: it dictates the level of linear F-actin polymerization, and it is required for appropriate branched actin polymerization via localization of SCAR and WASp. These studies provide new insight to the mechanisms of cell-cell fusion, the relationship between different regulators of actin polymerization, and invasive podosome formation that occurs in normal development and in disease.
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Affiliation(s)
- Su Deng
- Graduate Program in Physiology, Biophysics & Systems Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America
| | - Ingo Bothe
- Program in Developmental Biology, Sloan Kettering Institute, New York, New York, United States of America
| | - Mary K. Baylies
- Graduate Program in Physiology, Biophysics & Systems Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America
- Program in Developmental Biology, Sloan Kettering Institute, New York, New York, United States of America
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36
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Kim JH, Jin P, Duan R, Chen EH. Mechanisms of myoblast fusion during muscle development. Curr Opin Genet Dev 2015; 32:162-70. [PMID: 25989064 DOI: 10.1016/j.gde.2015.03.006] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 03/13/2015] [Accepted: 03/17/2015] [Indexed: 01/24/2023]
Abstract
The development and regeneration of skeletal muscle require the fusion of mononucleated muscle cells to form multinucleated, contractile muscle fibers. Studies using a simple genetic model, Drosophila melanogaster, have discovered many evolutionarily conserved fusion-promoting factors in vivo. Recent work in zebrafish and mouse also identified several vertebrate-specific factors required for myoblast fusion. Here, we integrate progress in multiple in vivo systems and highlight conceptual advance in understanding how muscle cell membranes are brought together for fusion. We focus on the molecular machinery at the fusogenic synapse and present a three-step model to describe the molecular and cellular events leading to fusion pore formation.
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Affiliation(s)
- Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Peng Jin
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Rui Duan
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States
| | - Elizabeth H Chen
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
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37
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Haralalka S, Abmayr SM. Tracing myoblast fusion in Drosophila embryos by fluorescent actin probes. Methods Mol Biol 2015; 1313:149-64. [PMID: 25947663 DOI: 10.1007/978-1-4939-2703-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Myoblast fusion in the Drosophila embryo is a highly elaborate process that is initiated by Founder Cells and Fusion-Competent Myoblasts (FCMs). It occurs through an asymmetric event in which actin foci assemble in the FCMs at points of cell-cell contact and direct the formation of membrane protrusions that drive fusion. Herein, we describe the approach that we have used to image in living embryos the highly dynamic actin foci and actin-rich projections that precede myoblast fusion. We discuss resources currently available for imaging actin and myogenesis, and our experience with these resources if available. This technical report is not intended to be comprehensive on providing instruction on standard microscopy practices or software utilization. However, we discuss microscope parameters that we have used in data collection, and our experience with image processing tools in data analysis.
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Affiliation(s)
- Shruti Haralalka
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO, 64110, USA
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38
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Maartens AP, Brown NH. The many faces of cell adhesion during Drosophila muscle development. Dev Biol 2015; 401:62-74. [DOI: 10.1016/j.ydbio.2014.12.038] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 12/17/2014] [Accepted: 12/19/2014] [Indexed: 10/24/2022]
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39
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Fine-Tuning of the Actin Cytoskeleton and Cell Adhesion During Drosophila Development by the Unconventional Guanine Nucleotide Exchange Factors Myoblast City and Sponge. Genetics 2015; 200:551-67. [PMID: 25908317 DOI: 10.1534/genetics.115.177063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 04/18/2015] [Indexed: 01/03/2023] Open
Abstract
The evolutionarily conserved Dock proteins function as unconventional guanine nucleotide exchange factors (GEFs). Upon binding to engulfment and cell motility (ELMO) proteins, Dock-ELMO complexes activate the Rho family of small GTPases to mediate a diverse array of biological processes, including cell motility, apoptotic cell clearance, and axon guidance. Overlapping expression patterns and functional redundancy among the 11 vertebrate Dock family members, which are subdivided into four families (Dock A, B, C, and D), complicate genetic analysis. In both vertebrate and invertebrate systems, the actin dynamics regulator, Rac, is the target GTPase of the Dock-A subfamily. However, it remains unclear whether Rac or Rap1 are the in vivo downstream GTPases of the Dock-B subfamily. Drosophila melanogaster is an excellent genetic model organism for understanding Dock protein function as its genome encodes one ortholog per subfamily: Myoblast city (Mbc; Dock A) and Sponge (Spg; Dock B). Here we show that the roles of Spg and Mbc are not redundant in the Drosophila somatic muscle or the dorsal vessel. Moreover, we confirm the in vivo role of Mbc upstream of Rac and provide evidence that Spg functions in concert with Rap1, possibly to regulate aspects of cell adhesion. Together these data show that Mbc and Spg can have different downstream GTPase targets. Our findings predict that the ability to regulate downstream GTPases is dependent on cellular context and allows for the fine-tuning of actin cytoskeletal or cell adhesion events in biological processes that undergo cell morphogenesis.
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40
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Wang ZH, Rabouille C, Geisbrecht ER. Loss of a Clueless-dGRASP complex results in ER stress and blocks Integrin exit from the perinuclear endoplasmic reticulum in Drosophila larval muscle. Biol Open 2015; 4:636-48. [PMID: 25862246 PMCID: PMC4434815 DOI: 10.1242/bio.201511551] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Drosophila Clueless (Clu) and its conserved orthologs are known for their role in the prevention of mitochondrial clustering. Here, we uncover a new role for Clu in the delivery of integrin subunits in muscle tissue. In clu mutants, αPS2 integrin, but not βPS integrin, abnormally accumulates in a perinuclear endoplasmic reticulum (ER) subdomain, a site that mirrors the endogenous localization of Clu. Loss of components essential for mitochondrial distribution do not phenocopy the clu mutant αPS2 phenotype. Conversely, RNAi knockdown of the DrosophilaGolgi reassembly and stacking protein GRASP55/65 (dGRASP) recapitulates clu defects, including the abnormal accumulation of αPS2 and larval locomotor activity. Both Clu and dGRASP proteins physically interact and loss of Clu displaces dGRASP from ER exit sites, suggesting that Clu cooperates with dGRASP for the exit of αPS2 from a perinuclear subdomain in the ER. We also found that Clu and dGRASP loss of function leads to ER stress and that the stability of the ER exit site protein Sec16 is severely compromised in the clu mutants, thus explaining the ER accumulation of αPS2. Remarkably, exposure of clu RNAi larvae to chemical chaperones restores both αPS2 delivery and functional ER exit sites. We propose that Clu together with dGRASP prevents ER stress and therefore maintains Sec16 stability essential for the functional organization of perinuclear early secretory pathway. This, in turn, is essential for integrin subunit αPS2 ER exit in Drosophila larval myofibers.
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Affiliation(s)
- Zong-Heng Wang
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City, MO 64110, USA
| | - Catherine Rabouille
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands The Department of Cell Biology, UMC Utrecht, 3584 CX Utrecht, The Netherlands
| | - Erika R Geisbrecht
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City, MO 64110, USA Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
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41
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Schulman VK, Dobi KC, Baylies MK. Morphogenesis of the somatic musculature in Drosophila melanogaster. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:313-34. [PMID: 25758712 DOI: 10.1002/wdev.180] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/28/2015] [Accepted: 01/30/2015] [Indexed: 12/22/2022]
Abstract
In Drosophila melanogaster, the somatic muscle system is first formed during embryogenesis, giving rise to the larval musculature. Later during metamorphosis, this system is destroyed and replaced by an entirely new set of muscles in the adult fly. Proper formation of the larval and adult muscles is critical for basic survival functions such as hatching and crawling (in the larva), walking and flying (in the adult), and feeding (at both larval and adult stages). Myogenesis, from mononucleated muscle precursor cells to multinucleated functional muscles, is driven by a number of cellular processes that have begun to be mechanistically defined. Once the mesodermal cells destined for the myogenic lineage have been specified, individual myoblasts fuse together iteratively to form syncytial myofibers. Combining cytoplasmic contents demands a level of intracellular reorganization that, most notably, leads to redistribution of the myonuclei to maximize internuclear distance. Signaling from extending myofibers induces terminal tendon cell differentiation in the ectoderm, which results in secure muscle-tendon attachments that are critical for muscle contraction. Simultaneously, muscles become innervated and undergo sarcomerogenesis to establish the contractile apparatus that will facilitate movement. The cellular mechanisms governing these morphogenetic events share numerous parallels to mammalian development, and the basic unit of all muscle, the myofiber, is conserved from flies to mammals. Thus, studies of Drosophila myogenesis and comparisons to muscle development in other systems highlight conserved regulatory programs of biomedical relevance to general muscle biology and studies of muscle disease.
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Affiliation(s)
- Victoria K Schulman
- Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA.,Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
| | - Krista C Dobi
- Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
| | - Mary K Baylies
- Cell and Developmental Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY, USA.,Program in Developmental Biology, Sloan Kettering Institute, New York, NY, USA
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42
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Kim JH, Ren Y, Ng WP, Li S, Son S, Kee YS, Zhang S, Zhang G, Fletcher DA, Robinson DN, Chen EH. Mechanical tension drives cell membrane fusion. Dev Cell 2015; 32:561-73. [PMID: 25684354 DOI: 10.1016/j.devcel.2015.01.005] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 11/14/2014] [Accepted: 01/10/2015] [Indexed: 01/05/2023]
Abstract
Membrane fusion is an energy-consuming process that requires tight juxtaposition of two lipid bilayers. Little is known about how cells overcome energy barriers to bring their membranes together for fusion. Previously, we have shown that cell-cell fusion is an asymmetric process in which an "attacking" cell drills finger-like protrusions into the "receiving" cell to promote cell fusion. Here, we show that the receiving cell mounts a Myosin II (MyoII)-mediated mechanosensory response to its invasive fusion partner. MyoII acts as a mechanosensor, which directs its force-induced recruitment to the fusion site, and the mechanosensory response of MyoII is amplified by chemical signaling initiated by cell adhesion molecules. The accumulated MyoII, in turn, increases cortical tension and promotes fusion pore formation. We propose that the protrusive and resisting forces from fusion partners put the fusogenic synapse under high mechanical tension, which helps to overcome energy barriers for membrane apposition and drives cell membrane fusion.
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Affiliation(s)
- Ji Hoon Kim
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yixin Ren
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Win Pin Ng
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Shuo Li
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sungmin Son
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Yee-Seir Kee
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shiliang Zhang
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Guofeng Zhang
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, MD 20892, USA
| | - Daniel A Fletcher
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Douglas N Robinson
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Elizabeth H Chen
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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43
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DRK/DOS/SOS converge with Crk/Mbc/dCed-12 to activate Rac1 during glial engulfment of axonal debris. Proc Natl Acad Sci U S A 2014; 111:12544-9. [PMID: 25099352 DOI: 10.1073/pnas.1403450111] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nervous system injury or disease leads to activation of glia, which govern postinjury responses in the nervous system. Axonal injury in Drosophila results in transcriptional up-regulation of the glial engulfment receptor Draper; there is extension of glial membranes to the injury site (termed activation), and then axonal debris is internalized and degraded. Loss of the small GTPase Rac1 from glia completely suppresses glial responses to injury, but upstream activators remain poorly defined. Loss of the Rac guanine nucleotide exchange factor (GEF) Crk/myoblast city (Mbc)/dCed-12 has no effect on glial activation, but blocks internalization and degradation of debris. Here we show that the signaling molecules downstream of receptor kinase (DRK) and daughter of sevenless (DOS) (mammalian homologs, Grb2 and Gab2, respectively) and the GEF son of sevenless (SOS) (mammalian homolog, mSOS) are required for efficient activation of glia after axotomy and internalization/degradation of axonal debris. At the earliest steps of glial activation, DRK/DOS/SOS function in a partially redundant manner with Crk/Mbc/dCed-12, with blockade of both complexes strongly suppressing all glial responses, similar to loss of Rac1. This work identifies DRK/DOS/SOS as the upstream Rac GEF complex required for glial responses to axonal injury, and demonstrates a critical requirement for multiple GEFs in efficient glial activation after injury and internalization/degradation of axonal debris.
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Abstract
Muscle fibers form as a result of myoblast fusion, yet the cell surface receptors regulating this process are unknown in vertebrates. In Drosophila, myoblast fusion involves the activation of the Rac pathway by the guanine nucleotide exchange factor Myoblast City and its scaffolding protein ELMO, downstream of cell-surface cell-adhesion receptors. We previously showed that the mammalian ortholog of Myoblast City, DOCK1, functions in an evolutionarily conserved manner to promote myoblast fusion in mice. In search for regulators of myoblast fusion, we identified the G-protein coupled receptor brain-specific angiogenesis inhibitor (BAI3) as a cell surface protein that interacts with ELMO. In cultured cells, BAI3 or ELMO1/2 loss of function severely impaired myoblast fusion without affecting differentiation and cannot be rescued by reexpression of BAI3 mutants deficient in ELMO binding. The related BAI protein family member, BAI1, is functionally distinct from BAI3, because it cannot rescue the myoblast fusion defects caused by the loss of BAI3 function. Finally, embryonic muscle precursor expression of a BAI3 mutant unable to bind ELMO was sufficient to block myoblast fusion in vivo. Collectively, our findings provide a role for BAI3 in the relay of extracellular fusion signals to their intracellular effectors, identifying it as an essential transmembrane protein for embryonic vertebrate myoblast fusion.
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Laurin M, Dumouchel A, Fukui Y, Côté JF. The Rac-specific exchange factors Dock1 and Dock5 are dispensable for the establishment of the glomerular filtration barrier in vivo. Small GTPases 2013; 4:221-30. [PMID: 24365888 DOI: 10.4161/sgtp.27430] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Podocytes are specialized kidney cells that form the kidney filtration barrier through the connection of their foot processes. Nephrin and Neph family transmembrane molecules at the surface of podocytes interconnect to form a unique type of cell-cell junction, the slit diaphragm, which acts as a molecular sieve. The cytoplasmic tails of Nephrin and Neph mediate cytoskeletal rearrangement that contributes to the maintenance of the filtration barrier. Nephrin and Neph1 orthologs are essential to regulate cell-cell adhesion and Rac-dependent actin rearrangement during Drosophila myoblast fusion. We hypothesized here that molecules regulating myoblast fusion in Drosophila could contribute to signaling downstream of Nephrin and Neph1 in podocytes. We found that Nephrin engagement promoted recruitment of the Rac exchange factor Dock1 to the membrane. Furthermore, Nephrin overexpression led to lamellipodia formation that could be blocked by inhibiting Rac1 activity. We generated in vivo mouse models to investigate whether Dock1 and Dock5 contribute to the formation and maintenance of the kidney filtration barrier. Our results indicate that while Dock1 and Dock5 are expressed in podocytes, their functions are not essential for the development of the glomerular filtration barrier. Furthermore, mice lacking Dock1 were not protected from LPS-induced podocyte effacement. Our data suggest that Dock1 and Dock5 are not the important exchange factors regulating Rac activity during the establishment and maintenance of the glomerular barrier.
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Affiliation(s)
- Mélanie Laurin
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada; Département de Médecine (Programmes de Biologie Moléculaire); Université de Montréal; Montréal, QC, Canada
| | - Annie Dumouchel
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada
| | - Yoshinori Fukui
- Division of Immunogenetics; Department of Immunobiology and Neuroscience; Medical Institute of Bioregulation; Kyushu University; Fukuoda, Japan
| | - Jean-François Côté
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada; Département de Médecine (Programmes de Biologie Moléculaire); Université de Montréal; Montréal, QC, Canada; Département de Biochimie; Université de Montréal; Montréal, QC, Canada; Division of Experimental Medicine; McGill University; Montréal, QC, Canada
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Liu ZC, Odell N, Geisbrecht ER. Drosophila importin-7 functions upstream of the Elmo signaling module to mediate the formation and stability of muscle attachments. J Cell Sci 2013; 126:5210-23. [PMID: 24046451 DOI: 10.1242/jcs.132241] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Establishment and maintenance of stable muscle attachments is essential for coordinated body movement. Studies in Drosophila have pioneered a molecular understanding of the morphological events in the conserved process of muscle attachment formation, including myofiber migration, muscle-tendon signaling, and stable junctional adhesion between muscle cells and their corresponding target insertion sites. In both Drosophila and vertebrate models, integrin complexes play a key role in the biogenesis and stability of muscle attachments through the interactions of integrins with extracellular matrix (ECM) ligands. We show that Drosophila importin-7 (Dim7) is an upstream regulator of the conserved Elmo-Mbc→Rac signaling pathway in the formation of embryonic muscle attachment sites (MASs). Dim7 is encoded by the moleskin (msk) locus and was identified as an Elmo-interacting protein. Both Dim7 and Elmo localize to the ends of myofibers coincident with the timing of muscle-tendon attachment in late myogenesis. Phenotypic analysis of elmo mutants reveal muscle attachment defects similar to those previously described for integrin mutants. Furthermore, Elmo and Dim7 interact both biochemically and genetically in the developing musculature. The muscle detachment phenotype resulting from mutations in the msk locus can be rescued by components in the Elmo signaling pathway, including the Elmo-Mbc complex, an activated Elmo variant, or a constitutively active form of Rac. In larval muscles, the localization of Dim7 and activated Elmo to the sites of muscle attachment is attenuated upon RNAi knockdown of integrin heterodimer complex components. Our results show that integrins function as upstream signals to mediate Dim7-Elmo enrichment to the MASs.
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Affiliation(s)
- Ze Cindy Liu
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri, Kansas City, MO 64110, USA
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Eguchi K, Yoshioka Y, Yoshida H, Morishita K, Miyata S, Hiai H, Yamaguchi M. The Drosophila DOCK family protein sponge is involved in differentiation of R7 photoreceptor cells. Exp Cell Res 2013; 319:2179-95. [DOI: 10.1016/j.yexcr.2013.05.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 05/16/2013] [Accepted: 05/18/2013] [Indexed: 01/17/2023]
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Phosphatidylserine receptor BAI1 and apoptotic cells as new promoters of myoblast fusion. Nature 2013; 497:263-7. [PMID: 23615608 PMCID: PMC3773542 DOI: 10.1038/nature12135] [Citation(s) in RCA: 236] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Accepted: 03/25/2013] [Indexed: 02/07/2023]
Abstract
Skeletal muscle arises from the fusion of precursor myoblasts into multinucleated myofibers1,2. While conserved transcription factors and signaling proteins involved in myogenesis have been identified, upstream regulators are less well understood. Here, we report an unexpected discovery that the membrane protein BAI1, previously linked to recognition of apoptotic cells by phagocytes3, promotes myoblast fusion. Endogenous BAI1 expression increased during myoblast fusion, and BAI1 overexpression enhanced myoblast fusion via signaling through ELMO/Dock180/Rac1 proteins4. During myoblast fusion, a fraction of myoblasts underwent apoptosis and exposed phosphatidylserine (PtdSer), an established ligand for BAI13. Blocking apoptosis potently impaired myoblast fusion, and adding back apoptotic myoblasts restored fusion. Furthermore, primary human myoblasts could be induced to form myotubes by adding apoptotic myoblasts, even under normal growth conditions. In vivo, myofibers from Bai1−/− mice are smaller than wild-type littermates. Muscle regeneration after injury was also impaired in Bai1−/− mice, highlighting a role for BAI1 in mammalian myogenesis. Collectively, these data identify signaling via the phosphatidylserine receptor BAI1 and apoptotic cells as novel promoters of myoblast fusion, with significant implications for muscle development and repair.
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Margaron Y, Fradet N, Côté JF. ELMO recruits actin cross-linking family 7 (ACF7) at the cell membrane for microtubule capture and stabilization of cellular protrusions. J Biol Chem 2012. [PMID: 23184944 DOI: 10.1074/jbc.m112.431825] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ELMO and DOCK180 proteins form an evolutionarily conserved module controlling Rac GTPase signaling during cell migration, phagocytosis, and myoblast fusion. Here, we identified the microtubule and actin-binding spectraplakin ACF7 as a novel ELMO-interacting partner. A C-terminal polyproline segment in ELMO and the last spectrin repeat of ACF7 mediate a direct interaction between these proteins. Co-expression of ELMO1 with ACF7 promoted the formation of long membrane protrusions during integrin-mediated cell spreading. Quantification of membrane dynamics established that coupling of ELMO and ACF7 increases the persistence of the protruding activity. Mechanistically, we uncovered a role for ELMO in the recruitment of ACF7 to the membrane to promote microtubule capture and stability. Functionally, these effects of ELMO and ACF7 on cytoskeletal dynamics required the Rac GEF DOCK180. In conclusion, our findings support a role for ELMO in protrusion stability by acting at the interface between the actin cytoskeleton and the microtubule network.
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Affiliation(s)
- Yoran Margaron
- Institut de Recherches Cliniques de Montréal, Montréal, Québec H2W 1R7, Canada
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50
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On the role of PDZ domain-encoding genes in Drosophila border cell migration. G3-GENES GENOMES GENETICS 2012; 2:1379-91. [PMID: 23173089 PMCID: PMC3484668 DOI: 10.1534/g3.112.004093] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 09/10/2012] [Indexed: 12/31/2022]
Abstract
Cells often move as collective groups during normal embryonic development and wound healing, although the mechanisms governing this type of migration are poorly understood. The Drosophila melanogaster border cells migrate as a cluster during late oogenesis and serve as a powerful in vivo genetic model for collective cell migration. To discover new genes that participate in border cell migration, 64 out of 66 genes that encode PDZ domain-containing proteins were systematically targeted by in vivo RNAi knockdown. The PDZ domain is one of the largest families of protein-protein interaction domains found in eukaryotes. Proteins that contain PDZ domains participate in a variety of biological processes, including signal transduction and establishment of epithelial apical-basal polarity. Targeting PDZ proteins effectively assesses a larger number of genes via the protein complexes and pathways through which these proteins function. par-6, a known regulator of border cell migration, was a positive hit and thus validated the approach. Knockdown of 14 PDZ domain genes disrupted migration with multiple RNAi lines. The candidate genes have diverse predicted cellular functions and are anticipated to provide new insights into the mechanisms that control border cell movement. As a test of this concept, two genes that disrupted migration were characterized in more detail: big bang and the Dlg5 homolog CG6509. We present evidence that Big bang regulates JAK/STAT signaling, whereas Dlg5/CG6509 maintains cluster cohesion. Moreover, these results demonstrate that targeting a selected class of genes by RNAi can uncover novel regulators of collective cell migration.
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