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Heron R, Amato C, Wood W, Davidson AJ. Understanding the diversity and dynamics of in vivo efferocytosis: Insights from the fly embryo. Immunol Rev 2023; 319:27-44. [PMID: 37589239 PMCID: PMC10952863 DOI: 10.1111/imr.13266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
The clearance of dead and dying cells, termed efferocytosis, is a rapid and efficient process and one that is critical for organismal health. The extraordinary speed and efficiency with which dead cells are detected and engulfed by immune cells within tissues presents a challenge to researchers who wish to unravel this fascinating process, since these fleeting moments of uptake are almost impossible to catch in vivo. In recent years, the fruit fly (Drosophila melanogaster) embryo has emerged as a powerful model to circumvent this problem. With its abundance of dying cells, specialist phagocytes and relative ease of live imaging, the humble fly embryo provides a unique opportunity to catch and study the moment of cell engulfment in real-time within a living animal. In this review, we explore the recent advances that have come from studies in the fly, and how live imaging and genetics have revealed a previously unappreciated level of diversity in the efferocytic program. A variety of efferocytic strategies across the phagocytic cell population ensure efficient and rapid clearance of corpses wherever death is encountered within the varied and complex setting of a multicellular living organism.
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Affiliation(s)
- Rosalind Heron
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
| | - Clelia Amato
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
| | - Will Wood
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
| | - Andrew J. Davidson
- Institute for Regeneration and RepairUniversity of EdinburghEdinburghUK
- School of Cancer SciencesWolfson Wohl Cancer Research Centre, University of GlasgowGlasgowUK
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2
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Fang HY, Forghani R, Clarke A, McQueen PG, Chandrasekaran A, O’Neill KM, Losert W, Papoian GA, Giniger E. Enabled primarily controls filopodial morphology, not actin organization, in the TSM1 growth cone in Drosophila. Mol Biol Cell 2023; 34:ar83. [PMID: 37223966 PMCID: PMC10398877 DOI: 10.1091/mbc.e23-01-0003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023] Open
Abstract
Ena/VASP proteins are processive actin polymerases that are required throughout animal phylogeny for many morphogenetic processes, including axon growth and guidance. Here we use in vivo live imaging of morphology and actin distribution to determine the role of Ena in promoting the growth of the TSM1 axon of the Drosophila wing. Altering Ena activity causes stalling and misrouting of TSM1. Our data show that Ena has a substantial impact on filopodial morphology in this growth cone but exerts only modest effects on actin distribution. This is in contrast to the main regulator of Ena, Abl tyrosine kinase, which was shown previously to have profound effects on actin and only mild effects on TSM1 growth cone morphology. We interpret these data as suggesting that the primary role of Ena in this axon may be to link actin to the morphogenetic processes of the plasma membrane, rather than to regulate actin organization itself. These data also suggest that a key role of Ena, acting downstream of Abl, may be to maintain consistent organization and reliable evolution of growth cone structure, even as Abl activity varies in response to guidance cues in the environment.
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Affiliation(s)
- Hsiao Yu Fang
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Rameen Forghani
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Akanni Clarke
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Philip G. McQueen
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Aravind Chandrasekaran
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20752
| | - Kate M. O’Neill
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
- Institute for Physical Sciences and Department of Physics, University of Maryland, College Park, MD 20752
| | - Wolfgang Losert
- Institute for Physical Sciences and Department of Physics, University of Maryland, College Park, MD 20752
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20752
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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3
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Vaibhvi V, Künzel S, Roeder T. Hemocytes and fat body cells, the only professional immune cell types in Drosophila, show strikingly different responses to systemic infections. Front Immunol 2022; 13:1040510. [PMID: 36505446 PMCID: PMC9726733 DOI: 10.3389/fimmu.2022.1040510] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/07/2022] [Indexed: 11/24/2022] Open
Abstract
The fruit fly Drosophila is an excellent model to study the response of different immunocompetent organs during systemic infection. In the present study, we intended to test the hypothesis that the only professional immune organs of the fly, the fat body and hemocytes, show substantial similarities in their responses to systemic infection. However, comprehensive transcriptome analysis of isolated organs revealed highly divergent transcript signatures, with the few commonly regulated genes encoding mainly classical immune effectors from the antimicrobial peptide family. The fat body and the hemocytes each have specific reactions that are not present in the other organ. Fat body-specific responses comprised those enabling an improved peptide synthesis and export. This reaction is accompanied by transcriptomic shifts enabling the use of the energy resources of the fat body more efficiently. Hemocytes, on the other hand, showed enhanced signatures related to phagocytosis. Comparing immune-induced signatures of both cell types with those of whole-body responses showed only a minimal correspondence, mostly restricted again to antimicrobial peptide genes. In summary, the two major immunocompetent cell types of Drosophila show highly specific responses to infection, which are closely linked to the primary function of the respective organ in the landscape of the systemic immune response.
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Affiliation(s)
- Vaibhvi Vaibhvi
- Department of Molecular Physiology, Zoology Institute, Kiel University, Kiel, Germany
| | - Sven Künzel
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Thomas Roeder
- Department of Molecular Physiology, Zoology Institute, Kiel University, Kiel, Germany,German Center for Lung Research, Airway Research Center North, Kiel, Germany,*Correspondence: Thomas Roeder,
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4
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Logan G, Chou WC, McCartney BM. A Diaphanous and Enabled-dependent asymmetric actin cable array repositions nuclei during Drosophila oogenesis. Development 2022; 149:275657. [DOI: 10.1242/dev.197442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 05/24/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Cells reposition their nuclei for diverse specialized functions through a wide variety of cytoskeletal mechanisms. During Drosophila oogenesis, 15 nurse cells connected by ring canals to each other and the oocyte contract, ‘dumping’ their cytoplasm into the oocyte. Prior to dumping, actin cables initiate from the nurse cell cortex and elongate toward their nuclei, pushing them away from ring canals to prevent obstruction. How the cable arrays reposition nuclei is unknown. We found that these arrays are asymmetric, with regional differences in actin cable growth rate dependent on the differential localization of the actin assembly factors Enabled and Diaphanous. Enabled mislocalization produces a uniform growth rate. In oocyte-contacting nurse cells with asymmetric cable arrays, nuclei move away from ring canals. With uniform arrays, these nuclei move toward the adjacent ring canal instead. This correlated with ring canal nuclear blockage and incomplete dumping. Our data suggest that nuclear repositioning relies on the regulated cortical localization of Diaphanous and Enabled to produce actin cable arrays with asymmetric growth that push nuclei away from ring canals, enabling successful oogenesis.
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Affiliation(s)
- Gregory Logan
- Carnegie Mellon University Department of Biological Sciences , , 4400 Fifth Avenue, Pittsburgh, PA 15213 , USA
| | - Wei-Chien Chou
- Carnegie Mellon University Department of Biological Sciences , , 4400 Fifth Avenue, Pittsburgh, PA 15213 , USA
| | - Brooke M. McCartney
- Carnegie Mellon University Department of Biological Sciences , , 4400 Fifth Avenue, Pittsburgh, PA 15213 , USA
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5
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Moore RP, Fogerson SM, Tulu US, Yu JW, Cox AH, Sican MA, Li D, Legant WR, Weigel AV, Crawford JM, Betzig E, Kiehart DP. Super-resolution microscopy reveals actomyosin dynamics in medioapical arrays. Mol Biol Cell 2022; 33:ar94. [PMID: 35544300 DOI: 10.1091/mbc.e21-11-0537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Arrays of actin filaments (F-actin) near the apical surface of epithelial cells (medioapical arrays) contribute to apical constriction and morphogenesis throughout phylogeny. Here, super-resolution approaches (grazing incidence structured illumination, GI-SIM and lattice light sheet, LLSM) microscopy resolve individual, fluorescently labeled F-actin and bipolar myosin filaments that drive amnioserosa cell shape changes during dorsal closure in Drosophila. In expanded cells, F-actin and myosin form loose, apically domed meshworks at the plasma membrane. The arrays condense as cells contract, drawing the domes into the plane of the junctional belts. As condensation continues, individual filaments are no longer uniformly apparent. As cells expand, arrays of actomyosin are again resolved - some F-actin turnover likely occurs, but a large fraction of existing filaments rearrange. In morphologically isotropic cells, actin filaments are randomly oriented and during contraction, are drawn together but remain essentially randomly oriented. In anisotropic cells, largely parallel actin filaments are drawn closer to one another. Our images offer unparalleled resolution of F-actin in embryonic tissue show that medioapical arrays are tightly apposed to the plasma membrane, are continuous with meshworks of lamellar F-actin and thereby constitute modified cell cortex. In concert with other tagged array components, super-resolution imaging of live specimens will offer new understanding of cortical architecture and function. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].
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Affiliation(s)
- Regan P Moore
- Biology Department, Duke University, Durham, NC, 27708, USA.,Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599, USA.,Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, 27599, USA and North Carolina State University, Raleigh, NC, 27695, USA
| | | | - U Serdar Tulu
- Biology Department, Duke University, Durham, NC, 27708, USA
| | - Jason W Yu
- Biology Department, Duke University, Durham, NC, 27708, USA
| | - Amanda H Cox
- Biology Department, Duke University, Durham, NC, 27708, USA
| | | | - Dong Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wesley R Legant
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, 27599, USA.,Joint Department of Biomedical Engineering, University of North Carolina, Chapel Hill, 27599, USA and North Carolina State University, Raleigh, NC, 27695, USA
| | - Aubrey V Weigel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA
| | | | - Eric Betzig
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA.,Departments of Physics and Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
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6
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Tóth K, Földi I, Mihály J. A Comparative Study of the Role of Formins in Drosophila Embryonic Dorsal Closure. Cells 2022; 11:cells11091539. [PMID: 35563844 PMCID: PMC9102720 DOI: 10.3390/cells11091539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/28/2022] [Accepted: 05/02/2022] [Indexed: 12/10/2022] Open
Abstract
Dorsal closure is a late embryogenesis process required to seal the epidermal hole on the dorsal side of the Drosophila embryo. This process involves the coordination of several forces generated in the epidermal cell layer and in the amnioserosa cells, covering the hole. Ultimately, these forces arise due to cytoskeletal rearrangements that induce changes in cell shape and result in tissue movement. While a number of cytoskeleton regulatory proteins have already been linked to dorsal closure, here we expand this list by demonstrating that four of the six Drosophila formin type actin assembly factors are needed to bring about the proper fusion of the epithelia. An analysis of the morphological and dynamic properties of dorsal closure in formin mutants revealed a differential contribution for each formin, although we found evidence for functional redundancies as well. Therefore, we propose that the four formins promote the formation of several, and only partly identical, actin structures each with a specific role in the mechanics of dorsal closure.
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Affiliation(s)
- Krisztina Tóth
- Biological Research Centre, Institute of Genetics, Temesvári krt. 62, H-6726 Szeged, Hungary; (K.T.); (I.F.)
- Doctoral School of Multidisciplinary Medical Science, Faculty of Medicine, University of Szeged, H-6725 Szeged, Hungary
| | - István Földi
- Biological Research Centre, Institute of Genetics, Temesvári krt. 62, H-6726 Szeged, Hungary; (K.T.); (I.F.)
| | - József Mihály
- Biological Research Centre, Institute of Genetics, Temesvári krt. 62, H-6726 Szeged, Hungary; (K.T.); (I.F.)
- Department of Genetics, University of Szeged, H-6726 Szeged, Hungary
- Correspondence:
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7
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Belyaeva V, Wachner S, Gyoergy A, Emtenani S, Gridchyn I, Akhmanova M, Linder M, Roblek M, Sibilia M, Siekhaus D. Fos regulates macrophage infiltration against surrounding tissue resistance by a cortical actin-based mechanism in Drosophila. PLoS Biol 2022; 20:e3001494. [PMID: 34990456 PMCID: PMC8735623 DOI: 10.1371/journal.pbio.3001494] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 11/25/2021] [Indexed: 12/20/2022] Open
Abstract
The infiltration of immune cells into tissues underlies the establishment of tissue-resident macrophages and responses to infections and tumors. Yet the mechanisms immune cells utilize to negotiate tissue barriers in living organisms are not well understood, and a role for cortical actin has not been examined. Here, we find that the tissue invasion of Drosophila macrophages, also known as plasmatocytes or hemocytes, utilizes enhanced cortical F-actin levels stimulated by the Drosophila member of the fos proto oncogene transcription factor family (Dfos, Kayak). RNA sequencing analysis and live imaging show that Dfos enhances F-actin levels around the entire macrophage surface by increasing mRNA levels of the membrane spanning molecular scaffold tetraspanin TM4SF, and the actin cross-linking filamin Cheerio, which are themselves required for invasion. Both the filamin and the tetraspanin enhance the cortical activity of Rho1 and the formin Diaphanous and thus the assembly of cortical actin, which is a critical function since expressing a dominant active form of Diaphanous can rescue the Dfos macrophage invasion defect. In vivo imaging shows that Dfos enhances the efficiency of the initial phases of macrophage tissue entry. Genetic evidence argues that this Dfos-induced program in macrophages counteracts the constraint produced by the tension of surrounding tissues and buffers the properties of the macrophage nucleus from affecting tissue entry. We thus identify strengthening the cortical actin cytoskeleton through Dfos as a key process allowing efficient forward movement of an immune cell into surrounding tissues. The infiltration of immune cells into tissue underlies the establishment of tissue-resident macrophages, and responses to infections and tumors, but how do they overcome tissue barriers? This study shows that macrophages upregulate the proto-oncogene Fos, increasing the density and crosslinking of cortical actin, thereby counteracting the tension of surrounding tissues and protecting the macrophage nucleus.
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Affiliation(s)
- Vera Belyaeva
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Stephanie Wachner
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Attila Gyoergy
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Shamsi Emtenani
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Igor Gridchyn
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Maria Akhmanova
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Markus Linder
- Institute of Cancer Research, Department of Medicine 1, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
| | - Marko Roblek
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Maria Sibilia
- Institute of Cancer Research, Department of Medicine 1, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria
| | - Daria Siekhaus
- Institute of Science and Technology Austria, Klosterneuburg, Austria
- * E-mail:
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8
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Ramesh P, Dey NS, Kanwal A, Mandal S, Mandal L. Relish plays a dynamic role in the niche to modulate Drosophila blood progenitor homeostasis in development and infection. eLife 2021; 10:67158. [PMID: 34292149 PMCID: PMC8363268 DOI: 10.7554/elife.67158] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 07/14/2021] [Indexed: 12/12/2022] Open
Abstract
Immune challenges demand the gearing up of basal hematopoiesis to combat infection. Little is known about how during development, this switch is achieved to take care of the insult. Here, we show that the hematopoietic niche of the larval lymph gland of Drosophila senses immune challenge and reacts to it quickly through the nuclear factor-κB (NF-κB), Relish, a component of the immune deficiency (Imd) pathway. During development, Relish is triggered by ecdysone signaling in the hematopoietic niche to maintain the blood progenitors. Loss of Relish causes an alteration in the cytoskeletal architecture of the niche cells in a Jun Kinase-dependent manner, resulting in the trapping of Hh implicated in progenitor maintenance. Notably, during infection, downregulation of Relish in the niche tilts the maintenance program toward precocious differentiation, thereby bolstering the cellular arm of the immune response.
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Affiliation(s)
- Parvathy Ramesh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, India.,Developmental Genetics Laboratory, IISER Mohali, SAS Nagar, Punjab, India
| | - Nidhi Sharma Dey
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, India.,Developmental Genetics Laboratory, IISER Mohali, SAS Nagar, Punjab, India
| | - Aditya Kanwal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, India.,Developmental Genetics Laboratory, IISER Mohali, SAS Nagar, Punjab, India
| | - Sudip Mandal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, India.,Molecular Cell and Developmental Biology Laboratory, IISER Mohali, SAS Nagar, Punjab, India
| | - Lolitika Mandal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, India.,Developmental Genetics Laboratory, IISER Mohali, SAS Nagar, Punjab, India
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9
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Yaniv SP, Meltzer H, Alyagor I, Schuldiner O. Developmental axon regrowth and primary neuron sprouting utilize distinct actin elongation factors. J Cell Biol 2021; 219:151569. [PMID: 32191286 PMCID: PMC7199854 DOI: 10.1083/jcb.201903181] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 11/06/2019] [Accepted: 02/14/2020] [Indexed: 01/23/2023] Open
Abstract
Intrinsic neurite growth potential is a key determinant of neuronal regeneration efficiency following injury. The stereotypical remodeling of Drosophila γ-neurons includes developmental regrowth of pruned axons to form adult specific connections, thereby offering a unique system to uncover growth potential regulators. Motivated by the dynamic expression in remodeling γ-neurons, we focus here on the role of actin elongation factors as potential regulators of developmental axon regrowth. We found that regrowth in vivo requires the actin elongation factors Ena and profilin, but not the formins that are expressed in γ-neurons. In contrast, primary γ-neuron sprouting in vitro requires profilin and the formin DAAM, but not Ena. Furthermore, we demonstrate that DAAM can compensate for the loss of Ena in vivo. Similarly, DAAM mutants express invariably high levels of Ena in vitro. Thus, we show that different linear actin elongation factors function in distinct contexts even within the same cell type and that they can partially compensate for each other.
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Affiliation(s)
- Shiri P Yaniv
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Hagar Meltzer
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Idan Alyagor
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Oren Schuldiner
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
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10
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McNeill EM, Thompson C, Berke B, Chou VT, Rusch J, Duckworth A, DeProto J, Taylor A, Gates J, Gertler F, Keshishian H, Van Vactor D. Drosophila enabled promotes synapse morphogenesis and regulates active zone form and function. Neural Dev 2020; 15:4. [PMID: 32183907 PMCID: PMC7076993 DOI: 10.1186/s13064-020-00141-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 02/25/2020] [Indexed: 11/10/2022] Open
Abstract
Background Recent studies of synapse form and function highlight the importance of the actin cytoskeleton in regulating multiple aspects of morphogenesis, neurotransmission, and neural plasticity. The conserved actin-associated protein Enabled (Ena) is known to regulate development of the Drosophila larval neuromuscular junction through a postsynaptic mechanism. However, the functions and regulation of Ena within the presynaptic terminal has not been determined. Methods Here, we use a conditional genetic approach to address a presynaptic role for Ena on presynaptic morphology and ultrastructure, and also examine the pathway in which Ena functions through epistasis experiments. Results We find that Ena is required to promote the morphogenesis of presynaptic boutons and branches, in contrast to its inhibitory role in muscle. Moreover, while postsynaptic Ena is regulated by microRNA-mediated mechanisms, presynaptic Ena relays the output of the highly conserved receptor protein tyrosine phosphatase Dlar and associated proteins including the heparan sulfate proteoglycan Syndecan, and the non-receptor Abelson tyrosine kinase to regulate addition of presynaptic varicosities. Interestingly, Ena also influences active zones, where it restricts active zone size, regulates the recruitment of synaptic vesicles, and controls the amplitude and frequency of spontaneous glutamate release. Conclusion We thus show that Ena, under control of the Dlar pathway, is required for presynaptic terminal morphogenesis and bouton addition and that Ena has active zone and neurotransmission phenotypes. Notably, in contrast to Dlar, Ena appears to integrate multiple pathways that regulate synapse form and function.
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Affiliation(s)
- Elizabeth M McNeill
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA.
| | - Cheryl Thompson
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Brett Berke
- Department of Biology, Yale University, New Haven, CT, USA
| | - Vivian T Chou
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
| | - Jannette Rusch
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - April Duckworth
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jamin DeProto
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Alicia Taylor
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA.,Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Julie Gates
- Department of Biology, Bucknell University, Lewisburg, PA, USA
| | - Frank Gertler
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, England
| | | | - David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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11
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The Arp2/3 complex and the formin, Diaphanous, are both required to regulate the size of germline ring canals in the developing egg chamber. Dev Biol 2020; 461:75-85. [PMID: 31945342 DOI: 10.1016/j.ydbio.2020.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/10/2020] [Accepted: 01/10/2020] [Indexed: 01/30/2023]
Abstract
Intercellular bridges are an essential structural feature found in both germline and somatic cells throughout the animal kingdom. Because of their large size, the germline intercellular bridges, or ring canals, in the developing fruit fly egg chamber are an excellent model to study the formation, stabilization, and growth of these structures. Within the egg chamber, the germline ring canals connect 15 supporting nurse cells to the developing oocyte, facilitating the transfer of materials required for successful oogenesis. The ring canals are derived from a stalled actomyosin contractile ring; once formed, additional actin and actin-binding proteins are recruited to the ring to support the 20-fold growth that accompanies oogenesis. These behaviors provide a unique model system to study the actin regulators that control incomplete cytokinesis, intercellular bridge formation, and growth. By temporally controlling their expression in the germline, we have demonstrated that the Arp2/3 complex and the formin, Diaphanous (Dia), coordinately regulate ring canal size and growth throughout oogenesis. Dia is required for successful incomplete cytokinesis and the initial stabilization of the germline ring canals. Once ring canals have formed, the Arp2/3 complex and Dia cooperate to determine ring canal size and maintain stability. Our data suggest that nurse cells must maintain a precise balance between the activity of these two nucleators during oogenesis.
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12
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Davidson AJ, Millard TH, Evans IR, Wood W. Ena orchestrates remodelling within the actin cytoskeleton to drive robust Drosophila macrophage chemotaxis. J Cell Sci 2019; 132:jcs.224618. [PMID: 30718364 PMCID: PMC6432709 DOI: 10.1242/jcs.224618] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/15/2019] [Indexed: 01/08/2023] Open
Abstract
The actin cytoskeleton is the engine that powers the inflammatory chemotaxis of immune cells to sites of tissue damage or infection. Here, we combine genetics with live in vivo imaging to investigate how cytoskeletal rearrangements drive macrophage recruitment to wounds in Drosophila. We find that the actin-regulatory protein Ena is a master regulator of lamellipodial dynamics in migrating macrophages, where it remodels the cytoskeleton to form linear filaments that can then be bundled together by the cross-linker Fascin (also known as Singed in flies). In contrast, the formin Dia generates rare, probing filopods for specialised functions that are not required for migration. The role of Ena in lamellipodial bundling is so fundamental that its overexpression increases bundling even in the absence of Fascin by marshalling the remaining cross-linking proteins to compensate. This reorganisation of the lamellipod generates cytoskeletal struts that push against the membrane to drive leading edge advancement and boost cell speed. Thus, Ena-mediated remodelling extracts the most from the cytoskeleton to power robust macrophage chemotaxis during their inflammatory recruitment to wounds. Summary: Macrophages must migrate to a variety of stimuli, including inflammatory wounds. We identify the actin-regulatory protein Ena as a master remodeller of the cytoskeleton within migrating macrophages in vivo.
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Affiliation(s)
- Andrew J Davidson
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Tom H Millard
- Faculty of Biology, Medicine and Health, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Iwan R Evans
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield S10 2RX, UK.,The Bateson Centre, University of Sheffield, Sheffield S10 2TN, UK
| | - Will Wood
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, University of Bristol, Bristol BS8 1TD, UK
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13
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Higashi T, Stephenson RE, Miller AL. Comprehensive analysis of formin localization in Xenopus epithelial cells. Mol Biol Cell 2018; 30:82-95. [PMID: 30379611 PMCID: PMC6337911 DOI: 10.1091/mbc.e18-02-0133] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Reorganization of the actin cytoskeleton is crucial for cellular processes, including cytokinesis and cell–cell junction remodeling. Formins are conserved processive actin-polymerizing machines that regulate actin dynamics by nucleating, elongating, and bundling linear actin filaments. Because the formin family is large, with at least 15 members in vertebrates, there have not been any comprehensive studies examining formin localization and function within a common cell type. Here, we characterized the localization of all 15 formins in epithelial cells of Xenopus laevis gastrula-stage embryos. Dia1 and Dia2 localized to tight junctions, while Fhod1 and Fhod3 localized to adherens junctions. Only Dia3 strongly localized at the cytokinetic contractile ring. The Diaphanous inhibitory domain–dimerization domain (DID-DD) region of Dia1 was sufficient for Dia1 localization, and overexpression of a Dia1 DID-DD fragment competitively removed Dia1 and Dia2 from cell–cell junctions. In Dia1 DID-DD–overexpressing cells, Dia1 and Dia2 were mislocalized to the contractile ring, and cells exhibited increased cytokinesis failure. This work provides a comprehensive analysis of the localization of all 15 vertebrate formins in epithelial cells and suggests that misregulated formin localization results in epithelial cytokinesis failure.
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Affiliation(s)
- Tomohito Higashi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Rachel E Stephenson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Ann L Miller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
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14
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Young LE, Latario CJ, Higgs HN. Roles for Ena/VASP proteins in FMNL3-mediated filopodial assembly. J Cell Sci 2018; 131:131/21/jcs220814. [PMID: 30373894 DOI: 10.1242/jcs.220814] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/25/2018] [Indexed: 02/01/2023] Open
Abstract
Filopodia are actin-dependent finger-like structures that protrude from the plasma membrane. Actin filament barbed-end-binding proteins localized to filopodial tips are key to filopodial assembly. Two classes of barbed-end-binding proteins are formins and Ena/VASP proteins, and both classes have been localized to filopodial tips in specific cellular contexts. Here, we examine the filopodial roles of the FMNL formins and Ena/VASP proteins in U2OS cells. FMNL3 suppression reduces filopodial assembly by 90%, and FMNL3 is enriched at >95% of filopodial tips. Suppression of VASP or Mena (also known as ENAH) reduces filopodial assembly by >75%. However, VASP and Mena do not display consistent filopodial tip localization, but are enriched in focal adhesions (FAs). Interestingly, >85% of FMNL3-containing filopodia are associated with FAs. Two situations increase Ena/VASP filopodial localization: (1) expression of myosin-X, and (2) actively spreading cells. In spreading cells, filopodia often mark sites of nascent adhesions. Interestingly, VASP suppression in spreading cells causes a significant increase in adhesion assembly at filopodial tips. This work demonstrates that, in U2OS cells, Ena/VASP proteins play roles in filopodia beyond those at filopodial tips.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Lorna E Young
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover NH 03755, USA
| | - Casey J Latario
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover NH 03755, USA
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover NH 03755, USA
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15
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Molinar-Inglis O, Oliver SL, Rudich P, Kunttas E, McCartney BM. APC2 associates with the actin cortex through a multipart mechanism to regulate cortical actin organization and dynamics in the Drosophila ovary. Cytoskeleton (Hoboken) 2018; 75:323-335. [PMID: 30019417 DOI: 10.1002/cm.21471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/24/2018] [Accepted: 06/19/2018] [Indexed: 01/20/2023]
Abstract
The actin cortex that lines the plasma membrane of most eukaryotic cells resists external mechanical forces and plays critical roles in a variety of cellular processes including morphogenesis, cytokinesis, and cell migration. Despite its ubiquity and significance, we understand relatively little about the composition, dynamics, and structure of the actin cortex. Adenomatous polyposis coli (APC) proteins regulate the actin and microtubule cytoskeletons through a variety of mechanisms, and in some contexts, APC proteins are cortically enriched. Here we show that APC2 regulates cortical actin dynamics in the follicular epithelium and the nurse cells of the Drosophila ovary and in addition affects the distribution of cortical actin at the apical side of the follicular epithelium. To understand how APC2 influences these properties of the actin cortex, we investigated the mechanisms controlling the cortical localization of APC2 in S2 cultured cells. We previously showed that the N-terminal half of APC2 containing the Armadillo repeats and the C-terminal 30 amino acids (C30) are together necessary and sufficient for APC2's cortical localization. Our work presented here supports a model that cortical localization of APC2 is governed in part by self-association through the N-terminal APC Self-Association Domain (ASAD) and a highly conserved coiled-coil within the C30 domain.
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Affiliation(s)
- Olivia Molinar-Inglis
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Stacie L Oliver
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Paige Rudich
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Ezgi Kunttas
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Brooke M McCartney
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania
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16
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Abstract
The actin cytoskeleton-a collection of actin filaments with their accessory and regulatory proteins-is the primary force-generating machinery in the cell. It can produce pushing (protrusive) forces through coordinated polymerization of multiple actin filaments or pulling (contractile) forces through sliding actin filaments along bipolar filaments of myosin II. Both force types are particularly important for whole-cell migration, but they also define and change the cell shape and mechanical properties of the cell surface, drive the intracellular motility and morphogenesis of membrane organelles, and allow cells to form adhesions with each other and with the extracellular matrix.
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Affiliation(s)
- Tatyana Svitkina
- Department of Biology, University of Pennsylvania, 221 Leidy Labs, Philadelphia, Pennsylvania 19104
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17
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Quantitative modelling of epithelial morphogenesis: integrating cell mechanics and molecular dynamics. Semin Cell Dev Biol 2017; 67:153-160. [DOI: 10.1016/j.semcdb.2016.07.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 06/28/2016] [Accepted: 07/27/2016] [Indexed: 12/22/2022]
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18
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Xie S, Mason FM, Martin AC. Loss of Gα12/13 exacerbates apical area dependence of actomyosin contractility. Mol Biol Cell 2016; 27:3526-3536. [PMID: 27489340 PMCID: PMC5221585 DOI: 10.1091/mbc.e16-05-0305] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/27/2016] [Indexed: 01/23/2023] Open
Abstract
Gα12/13 loss causes cells with a larger apical area to constrict later than smaller cells, leading to uncoordinated constriction. Apical area influences actin density, myosin regulation, and E-cadherin levels. Thus Gα12/13 is crucial for the robust initiation of contraction in a tissue in which cells initially have heterogeneous apical areas. During development, coordinated cell shape changes alter tissue shape. In the Drosophila ventral furrow and other epithelia, apical constriction of hundreds of epithelial cells folds the tissue. Genes in the Gα12/13 pathway coordinate collective apical constriction, but the mechanism of coordination is poorly understood. Coupling live-cell imaging with a computational approach to identify contractile events, we discovered that differences in constriction behavior are biased by initial cell shape. Disrupting Gα12/13 exacerbates this relationship. Larger apical area is associated with delayed initiation of contractile pulses, lower apical E-cadherin and F-actin levels, and aberrantly mobile Rho-kinase structures. Our results suggest that loss of Gα12/13 disrupts apical actin cortex organization and pulse initiation in a size-dependent manner. We propose that Gα12/13 robustly organizes the apical cortex despite variation in apical area to ensure the timely initiation of contractile pulses in a tissue with heterogeneity in starting cell shape.
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Affiliation(s)
- Shicong Xie
- Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Frank M Mason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
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19
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Davidson AJ, Wood W. Unravelling the Actin Cytoskeleton: A New Competitive Edge? Trends Cell Biol 2016; 26:569-576. [PMID: 27133808 PMCID: PMC4961066 DOI: 10.1016/j.tcb.2016.04.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 12/27/2022]
Abstract
Dynamic rearrangements in the actin cytoskeleton underlie a wide range of cell behaviours, which in turn contribute to many aspects of human health including embryogenesis, cancer metastasis, wound healing, and inflammation. Precise control of the actin cytoskeleton requires the coordinated activity of a diverse set of different actin regulators. However, our current understanding of the actin cytoskeleton has focused on how individual actin regulatory pathways function in isolation from one another. Recently, competition has emerged as a means by which different actin assembly factors can influence each other's activity at the cellular level. Here such findings will be used to explore the possibility that competition within the actin cytoskeleton confers cellular plasticity and the ability to prioritise multiple conflicting stimuli. Cells maintain a dynamic actin cytoskeleton by carefully balancing the activities of a diverse collection of actin regulators. Recent findings suggest that key actin assembly factors limit one another through competition over a finite pool of G-actin. Increasing or decreasing cellular G-actin influences the type of F-actin network generated. The actin monomer binding protein profilin is responsible for proportioning how much G-actin is available to each assembly factor. Cytoskeletal competition appears universally conserved from yeast to human. Competition ensures cytoskeletal homeostasis and integration/coordination between the different actin regulatory pathways to support dynamic cell behaviour.
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Affiliation(s)
- Andrew J Davidson
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, Biomedical Science Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Will Wood
- School of Cellular and Molecular Medicine, Faculty of Biomedical Sciences, Biomedical Science Building, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
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20
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Shekhar S, Kerleau M, Kühn S, Pernier J, Romet-Lemonne G, Jégou A, Carlier MF. Formin and capping protein together embrace the actin filament in a ménage à trois. Nat Commun 2015; 6:8730. [PMID: 26564775 PMCID: PMC4660058 DOI: 10.1038/ncomms9730] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 09/24/2015] [Indexed: 11/09/2022] Open
Abstract
Proteins targeting actin filament barbed ends play a pivotal role in motile processes. While formins enhance filament assembly, capping protein (CP) blocks polymerization. On their own, they both bind barbed ends with high affinity and very slow dissociation. Their barbed-end binding is thought to be mutually exclusive. CP has recently been shown to be present in filopodia and controls their morphology and dynamics. Here we explore how CP and formins may functionally coregulate filament barbed-end assembly. We show, using kinetic analysis of individual filaments by microfluidics-assisted fluorescence microscopy, that CP and mDia1 formin are able to simultaneously bind barbed ends. This is further confirmed using single-molecule imaging. Their mutually weakened binding enables rapid displacement of one by the other. We show that formin FMNL2 behaves similarly, thus suggesting that this is a general property of formins. Implications in filopodia regulation and barbed-end structural regulation are discussed.
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Affiliation(s)
- Shashank Shekhar
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
| | - Mikael Kerleau
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
| | - Sonja Kühn
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
| | - Julien Pernier
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
| | - Guillaume Romet-Lemonne
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
| | - Antoine Jégou
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
| | - Marie-France Carlier
- Cytoskeleton Dynamics and Cell Motility, Department of Biochemistry, Biophysics and Structural Biology, I2BC, CNRS, 91198 Gif-sur-Yvette, France
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21
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Flores-Benitez D, Knust E. Crumbs is an essential regulator of cytoskeletal dynamics and cell-cell adhesion during dorsal closure in Drosophila. eLife 2015; 4. [PMID: 26544546 PMCID: PMC4718732 DOI: 10.7554/elife.07398] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 11/06/2015] [Indexed: 12/12/2022] Open
Abstract
The evolutionarily conserved Crumbs protein is required for epithelial polarity and morphogenesis. Here we identify a novel role of Crumbs as a negative regulator of actomyosin dynamics during dorsal closure in the Drosophila embryo. Embryos carrying a mutation in the FERM (protein 4.1/ezrin/radixin/moesin) domain-binding motif of Crumbs die due to an overactive actomyosin network associated with disrupted adherens junctions. This phenotype is restricted to the amnioserosa and does not affect other embryonic epithelia. This function of Crumbs requires DMoesin, the Rho1-GTPase, class-I p21-activated kinases and the Arp2/3 complex. Data presented here point to a critical role of Crumbs in regulating actomyosin dynamics, cell junctions and morphogenesis. DOI:http://dx.doi.org/10.7554/eLife.07398.001 A layer of epithelial cells covers the body surface of animals. Epithelial cells have a property known as polarity; this means that they have two different poles, one of which is in contact with the environment. Midway through embryonic development, the Drosophila embryo is covered by two kinds of epithelial sheets; the epidermis on the front, the belly and the sides of the embryo, and the amnioserosa on the back. In the second half of embryonic development, the amnioserosa is brought into the embryo in a process called dorsal closure, while the epidermis expands around the back of the embryo to encompass it. One of the major activities driving dorsal closure is the contraction of amnioserosa cells. This contraction depends on the highly dynamic activity of the protein network that helps give cells their shape, known as the actomyosin cytoskeleton. One major question in the field is how changes in the actomyosin cytoskeleton are controlled as tissues take shape (a process known as “morphogenesis”) and how the integrity of epithelial tissues is maintained during these processes. A key regulator of epidermal and amnioserosa polarity is an evolutionarily conserved protein called Crumbs. The epithelial tissues of mutant embryos that do not produce Crumbs lose polarity and integrity, and the embryos fail to develop properly. Flores-Benitez and Knust have now studied the role of Crumbs in the morphogenesis of the amnioserosa during dorsal closure. This revealed that fly embryos that produce a mutant Crumbs protein that cannot interact with a protein called Moesin (which links the cell membrane and the actomyosin cytoskeleton) are unable to complete dorsal closure. Detailed analyses showed that this failure of dorsal closure is due to the over-activity of the actomyosin cytoskeleton in the amnioserosa. This results in increased and uncoordinated contractions of the cells, and is accompanied by defects in cell-cell adhesion that ultimately cause the amnioserosa to lose integrity. Flores-Benitez and Knust’s genetic analyses further showed that several different signalling systems participate in this process. Flores-Benitez and Knust’s results reveal an unexpected role of Crumbs in coordinating polarity, actomyosin activity and cell-cell adhesion. Further work is now needed to understand the molecular mechanisms and interactions that enable Crumbs to coordinate these processes; in particular, to unravel how Crumbs influences the periodic contractions that drive changes in cell shape. It will also be important to investigate whether Crumbs is involved in similar mechanisms that operate in other developmental events in which actomyosin oscillations have been linked to tissue morphogenesis. DOI:http://dx.doi.org/10.7554/eLife.07398.002
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Affiliation(s)
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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22
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Young LE, Heimsath EG, Higgs HN. Cell type-dependent mechanisms for formin-mediated assembly of filopodia. Mol Biol Cell 2015; 26:4646-59. [PMID: 26446836 PMCID: PMC4678021 DOI: 10.1091/mbc.e15-09-0626] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/01/2015] [Indexed: 11/11/2022] Open
Abstract
Filopodia are finger-like protrusions from the plasma membrane and are of fundamental importance to cellular physiology, but the mechanisms governing their assembly are still in question. One model, called convergent elongation, proposes that filopodia arise from Arp2/3 complex-nucleated dendritic actin networks, with factors such as formins elongating these filaments into filopodia. We test this model using constitutively active constructs of two formins, FMNL3 and mDia2. Surprisingly, filopodial assembly requirements differ between suspension and adherent cells. In suspension cells, Arp2/3 complex is required for filopodial assembly through either formin. In contrast, a subset of filopodia remains after Arp2/3 complex inhibition in adherent cells. In adherent cells only, mDia1 and VASP also contribute to filopodial assembly, and filopodia are disproportionately associated with focal adhesions. We propose an extension of the existing models for filopodial assembly in which any cluster of actin filament barbed ends in proximity to the plasma membrane, either Arp2/3 complex dependent or independent, can initiate filopodial assembly by specific formins.
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Affiliation(s)
- Lorna E Young
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Ernest G Heimsath
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Henry N Higgs
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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23
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Hunter MV, Lee DM, Harris TJC, Fernandez-Gonzalez R. Polarized E-cadherin endocytosis directs actomyosin remodeling during embryonic wound repair. J Cell Biol 2015; 210:801-16. [PMID: 26304727 PMCID: PMC4555830 DOI: 10.1083/jcb.201501076] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 07/14/2015] [Indexed: 12/26/2022] Open
Abstract
Clathrin, dynamin, and ARF6 accumulate around wounds in Drosophila embryos in a calcium- and actomyosin-dependent manner and drive polarized E-cadherin endocytosis, which is necessary for actomyosin remodeling during wound repair. Embryonic epithelia have a remarkable ability to rapidly repair wounds. A supracellular actomyosin cable around the wound coordinates cellular movements and promotes wound closure. Actomyosin cable formation is accompanied by junctional rearrangements at the wound margin. We used in vivo time-lapse quantitative microscopy to show that clathrin, dynamin, and the ADP-ribosylation factor 6, three components of the endocytic machinery, accumulate around wounds in Drosophila melanogaster embryos in a process that requires calcium signaling and actomyosin contractility. Blocking endocytosis with pharmacological or genetic approaches disrupted wound repair. The defect in wound closure was accompanied by impaired removal of E-cadherin from the wound edge and defective actomyosin cable assembly. E-cadherin overexpression also resulted in reduced actin accumulation around wounds and slower wound closure. Reducing E-cadherin levels in embryos in which endocytosis was blocked rescued actin localization to the wound margin. Our results demonstrate a central role for endocytosis in wound healing and indicate that polarized E-cadherin endocytosis is necessary for actomyosin remodeling during embryonic wound repair.
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Affiliation(s)
- Miranda V Hunter
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Donghoon M Lee
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Rodrigo Fernandez-Gonzalez
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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24
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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: 29] [Impact Index Per Article: 3.2] [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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25
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Matsubayashi Y, Coulson-Gilmer C, Millard TH. Endocytosis-dependent coordination of multiple actin regulators is required for wound healing. J Cell Biol 2015. [PMID: 26216900 PMCID: PMC4523608 DOI: 10.1083/jcb.201411037] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ability to heal wounds efficiently is essential for life. After wounding of an epithelium, the cells bordering the wound form dynamic actin protrusions and/or a contractile actomyosin cable, and these actin structures drive wound closure. Despite their importance in wound healing, the molecular mechanisms that regulate the assembly of these actin structures at wound edges are not well understood. In this paper, using Drosophila melanogaster embryos, we demonstrate that Diaphanous, SCAR, and WASp play distinct but overlapping roles in regulating actin assembly during wound healing. Moreover, we show that endocytosis is essential for wound edge actin assembly and wound closure. We identify adherens junctions (AJs) as a key target of endocytosis during wound healing and propose that endocytic remodeling of AJs is required to form "signaling centers" along the wound edge that control actin assembly. We conclude that coordination of actin assembly, AJ remodeling, and membrane traffic is required for the construction of a motile leading edge during wound healing.
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Affiliation(s)
- Yutaka Matsubayashi
- The Healing Foundation Centre, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Camilla Coulson-Gilmer
- The Healing Foundation Centre, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
| | - Tom H Millard
- The Healing Foundation Centre, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK
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26
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Davis JR, Luchici A, Mosis F, Thackery J, Salazar JA, Mao Y, Dunn GA, Betz T, Miodownik M, Stramer BM. Inter-cellular forces orchestrate contact inhibition of locomotion. Cell 2015; 161:361-73. [PMID: 25799385 PMCID: PMC4398973 DOI: 10.1016/j.cell.2015.02.015] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 11/24/2014] [Accepted: 01/27/2015] [Indexed: 11/15/2022]
Abstract
Contact inhibition of locomotion (CIL) is a multifaceted process that causes many cell types to repel each other upon collision. During development, this seemingly uncoordinated reaction is a critical driver of cellular dispersion within embryonic tissues. Here, we show that Drosophila hemocytes require a precisely orchestrated CIL response for their developmental dispersal. Hemocyte collision and subsequent repulsion involves a stereotyped sequence of kinematic stages that are modulated by global changes in cytoskeletal dynamics. Tracking actin retrograde flow within hemocytes in vivo reveals synchronous reorganization of colliding actin networks through engagement of an inter-cellular adhesion. This inter-cellular actin-clutch leads to a subsequent build-up in lamellar tension, triggering the development of a transient stress fiber, which orchestrates cellular repulsion. Our findings reveal that the physical coupling of the flowing actin networks during CIL acts as a mechanotransducer, allowing cells to haptically sense each other and coordinate their behaviors.
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Affiliation(s)
- John R Davis
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Andrei Luchici
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Department of Mechanical Engineering, University College London, London WC2R 2LS, UK
| | - Fuad Mosis
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - James Thackery
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Jesus A Salazar
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Yanlan Mao
- Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
| | - Graham A Dunn
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Timo Betz
- Centre de Recherche, Institut Curie, Paris, UMR168, France
| | - Mark Miodownik
- Department of Mechanical Engineering, University College London, London WC2R 2LS, UK.
| | - Brian M Stramer
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
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27
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Lu Q, Adler PN. The diaphanous gene of Drosophila interacts antagonistically with multiple wing hairs and plays a key role in wing hair morphogenesis. PLoS One 2015; 10:e0115623. [PMID: 25730111 PMCID: PMC4346269 DOI: 10.1371/journal.pone.0115623] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/25/2014] [Indexed: 11/18/2022] Open
Abstract
The Drosophila wing is covered by an array of distally pointing hairs that has served as a key model system for studying planar cell polarity (PCP). The adult cuticular hairs are formed in the pupae from cell extensions that contain extensive actin filaments and microtubules. The importance of the actin cytoskeleton for hair growth and morphogenesis is clear from the wide range of phenotypes seen in mutations in well-known actin regulators. Formin proteins promote the formation of long actin filaments of the sort thought to be important for hair growth. We report here that the formin encoding diaphanous (dia) gene plays a key role in hair morphogenesis. Both loss of function mutations and the expression of a constitutively active Dia led to cells forming both morphologically abnormal hairs and multiple hairs. The conserved frizzled (fz)/starry night (stan) PCP pathway functions to restrict hair initiation and activation of the cytoskeleton to the distal most part of wing cells. It also ensures the formation of a single hair per cell. Our data suggest that the localized inhibition of Dia activity may be part of this mechanism. We found the expression of constitutively active Dia greatly expands the region for activation of the cytoskeleton and that dia functions antagonistically with multiple wing hairs (mwh), the most downstream member of the fz/stan pathway. Further we established that purified fragments of Dia and Mwh could be co-immunoprecipitated suggesting the genetic interaction could reflect a direct physical interaction.
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Affiliation(s)
- Qiuheng Lu
- Biology Department, University of Virginia, Charlottesville, Virginia, United States of America
| | - Paul N. Adler
- Biology Department, University of Virginia, Charlottesville, Virginia, United States of America
- Cell Biology Department, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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28
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Haralalka S, Shelton C, Cartwright HN, Guo F, Trimble R, Kumar RP, Abmayr SM. Live imaging provides new insights on dynamic F-actin filopodia and differential endocytosis during myoblast fusion in Drosophila. PLoS One 2014; 9:e114126. [PMID: 25474591 PMCID: PMC4256407 DOI: 10.1371/journal.pone.0114126] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 10/28/2014] [Indexed: 11/29/2022] Open
Abstract
The process of myogenesis includes the recognition, adhesion, and fusion of committed myoblasts into multinucleate syncytia. In the larval body wall muscles of Drosophila, this elaborate process is initiated by Founder Cells and Fusion-Competent Myoblasts (FCMs), and cell adhesion molecules Kin-of-IrreC (Kirre) and Sticks-and-stones (Sns) on their respective surfaces. The FCMs appear to provide the driving force for fusion, via the assembly of protrusions associated with branched F-actin and the WASp, SCAR and Arp2/3 pathways. In the present study, we utilize the dorsal pharyngeal musculature that forms in the Drosophila embryo as a model to explore myoblast fusion and visualize the fusion process in live embryos. These muscles rely on the same cell types and genes as the body wall muscles, but are amenable to live imaging since they do not undergo extensive morphogenetic movement during formation. Time-lapse imaging with F-actin and membrane markers revealed dynamic FCM-associated actin-enriched protrusions that rapidly extend and retract into the myotube from different sites within the actin focus. Ultrastructural analysis of this actin-enriched area showed that they have two morphologically distinct structures: wider invasions and/or narrow filopodia that contain long linear filaments. Consistent with this, formin Diaphanous (Dia) and branched actin nucleator, Arp3, are found decorating the filopodia or enriched at the actin focus, respectively, indicating that linear actin is present along with branched actin at sites of fusion in the FCM. Gain-of-function Dia and loss-of-function Arp3 both lead to fusion defects, a decrease of F-actin foci and prominent filopodia from the FCMs. We also observed differential endocytosis of cell surface components at sites of fusion, with actin reorganizing factors, WASp and SCAR, and Kirre remaining on the myotube surface and Sns preferentially taken up with other membrane proteins into early endosomes and lysosomes in the myotube.
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Affiliation(s)
- Shruti Haralalka
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Claude Shelton
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Heather N. Cartwright
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Fengli Guo
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Rhonda Trimble
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Ram P. Kumar
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
| | - Susan M. Abmayr
- Stowers Institute for Medical Research, Kansas City, Missouri, 64110, United States of America
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas, 66160, United States of America
- * E-mail:
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29
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Sun H, Al-Romaih KI, MacRae CA, Pollak MR. Human Kidney Disease-causing INF2 Mutations Perturb Rho/Dia Signaling in the Glomerulus. EBioMedicine 2014; 1:107-15. [PMID: 26086034 PMCID: PMC4457406 DOI: 10.1016/j.ebiom.2014.11.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/08/2014] [Accepted: 11/11/2014] [Indexed: 01/10/2023] Open
Abstract
Mutations in Inverted Formin 2 (INF2), a diaphanous formin family protein that regulates actin cytoskeleton dynamics, cause focal segmental glomerulosclerosis (FSGS) and Charcot-Marie-Tooth Disease (CMT) in humans. In addition to directly remodeling actin filaments in vitro, we have shown that INF2 regulates intracellular actin dynamics and actin dependent cellular behavior by opposing Rhoa/Dia signaling. As a step towards a better understanding of the human kidney disease, we wanted to explore the relevance of these findings to the in vivo situation. We used dose dependent knockdown of INF2 to first define an in vivo model and establish an overt glomerular phenotype in zebrafish. This simple assay was validated by rescue with wild type INF2 confirming the specificity of the findings. The edema, podocyte dysfunction, and an altered glomerular filtration barrier observed in the zebrafish pronephros correlate with mistrafficking of glomerular slit diaphragm proteins, defective slit-diaphragm signaling, and disinhibited diaphanous formin (mDia) activity. In contrast to wild-type human INF2, INF2 mutants associated with kidney disease fail to rescue the zINF2 morphant phenotype. Of particular interest, this INF2 knockdown phenotype is also rescued by loss of either RhoA or Dia2. This simple assay allows the demonstration that INF2 functions, at least in part, to modulate Dia-mediated Rho signaling, and that disease causing mutations specifically impair this regulatory function. These data support a model in which disease-associated diaphanous inhibitory domain (DID) mutants in INF2 interfere with its binding to and inhibition of Dia, leading to uncontrolled Rho/Dia signaling and perturbed actin dynamics. Methods to fine tune Rho signaling in the glomerulus may lead to new approaches to therapy in humans.
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Affiliation(s)
- Hua Sun
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, United States ; Harvard Medical School, Boston, MA 02215, United States ; Iowa University Children's Hospital, Iowa City, IA 52242, United States
| | - Khaldoun I Al-Romaih
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, United States ; Harvard Medical School, Boston, MA 02215, United States
| | - Calum A MacRae
- Harvard Medical School, Boston, MA 02215, United States ; Cardiology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, United States ; Broad Institute of Harvard and MIT, Cambridge, MA, United States
| | - Martin R Pollak
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, United States ; Harvard Medical School, Boston, MA 02215, United States ; Broad Institute of Harvard and MIT, Cambridge, MA, United States
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Havrylenko S, Noguera P, Abou-Ghali M, Manzi J, Faqir F, Lamora A, Guérin C, Blanchoin L, Plastino J. WAVE binds Ena/VASP for enhanced Arp2/3 complex-based actin assembly. Mol Biol Cell 2014; 26:55-65. [PMID: 25355952 PMCID: PMC4279229 DOI: 10.1091/mbc.e14-07-1200] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A dual in vitro/in vivo approach is used to show that WAVE directly binds Ena/VASP, coordinating its activity with that of the Arp2/3 complex for enhanced actin assembly. The WAVE complex is the main activator of the Arp2/3 complex for actin filament nucleation and assembly in the lamellipodia of moving cells. Other important players in lamellipodial protrusion are Ena/VASP proteins, which enhance actin filament elongation. Here we examine the molecular coordination between the nucleating activity of the Arp2/3 complex and the elongating activity of Ena/VASP proteins for the formation of actin networks. Using an in vitro bead motility assay, we show that WAVE directly binds VASP, resulting in an increase in Arp2/3 complex–based actin assembly. We show that this interaction is important in vivo as well, for the formation of lamellipodia during the ventral enclosure event of Caenorhabditis elegans embryogenesis. Ena/VASP's ability to bind F-actin and profilin-complexed G-actin are important for its effect, whereas Ena/VASP tetramerization is not necessary. Our data are consistent with the idea that binding of Ena/VASP to WAVE potentiates Arp2/3 complex activity and lamellipodial actin assembly.
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Affiliation(s)
- Svitlana Havrylenko
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
| | - Philippe Noguera
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
| | - Majdouline Abou-Ghali
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
| | - John Manzi
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
| | - Fahima Faqir
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
| | - Audrey Lamora
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
| | - Christophe Guérin
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, CNRS/CEA/INRA/UJF, Grenoble 38054, France
| | - Laurent Blanchoin
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, CNRS/CEA/INRA/UJF, Grenoble 38054, France
| | - Julie Plastino
- Institut Curie, Centre de Recherche Centre National de la Recherche Scientifique, Unité Mixte de Recherche 168 Université Pierre et Marie Curie, Paris F-75248, France
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31
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Nowotarski SH, McKeon N, Moser RJ, Peifer M. The actin regulators Enabled and Diaphanous direct distinct protrusive behaviors in different tissues during Drosophila development. Mol Biol Cell 2014; 25:3147-65. [PMID: 25143400 PMCID: PMC4196866 DOI: 10.1091/mbc.e14-05-0951] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Actin-based protrusions are important for signaling and migration during development and homeostasis. Gain- and loss-of-function and quantitative approaches are used to define differential roles for the actin elongation factors Diaphanous and Enabled in regulating distinct protrusive behaviors in different tissues during Drosophila morphogenesis. Actin-based protrusions are important for signaling and migration during development and homeostasis. Defining how different tissues in vivo craft diverse protrusive behaviors using the same genomic toolkit of actin regulators is a current challenge. The actin elongation factors Diaphanous and Enabled both promote barbed-end actin polymerization and can stimulate filopodia in cultured cells. However, redundancy in mammals and Diaphanous’ role in cytokinesis limited analysis of whether and how they regulate protrusions during development. We used two tissues driving Drosophila dorsal closure—migratory leading-edge (LE) and nonmigratory amnioserosal (AS) cells—as models to define how cells shape distinct protrusions during morphogenesis. We found that nonmigratory AS cells produce filopodia that are morphologically and dynamically distinct from those of LE cells. We hypothesized that differing Enabled and/or Diaphanous activity drives these differences. Combining gain- and loss-of-function with quantitative approaches revealed that Diaphanous and Enabled each regulate filopodial behavior in vivo and defined a quantitative “fingerprint”—the protrusive profile—which our data suggest is characteristic of each actin regulator. Our data suggest that LE protrusiveness is primarily Enabled driven, whereas Diaphanous plays the primary role in the AS, and reveal each has roles in dorsal closure, but its robustness ensures timely completion in their absence.
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Affiliation(s)
- Stephanie H Nowotarski
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Natalie McKeon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Rachel J Moser
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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32
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Barzik M, McClain LM, Gupton SL, Gertler FB. Ena/VASP regulates mDia2-initiated filopodial length, dynamics, and function. Mol Biol Cell 2014; 25:2604-19. [PMID: 24989797 PMCID: PMC4148250 DOI: 10.1091/mbc.e14-02-0712] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Filopodia are long plasma membrane extensions involved in the formation of adhesive, contractile, and protrusive actin-based structures in spreading and migrating cells. Whether filopodia formed by different molecular mechanisms equally support these cellular functions is unresolved. We used Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP)-deficient MV(D7) fibroblasts, which are also devoid of endogenous mDia2, as a model system to investigate how these different actin regulatory proteins affect filopodia morphology and dynamics independently of one another. Filopodia initiated by either Ena/VASP or mDia2 contained similar molecular inventory but differed significantly in parameters such as number, length, F-actin organization, lifetime, and protrusive persistence. Moreover, in the absence of Ena/VASP, filopodia generated by mDia2 did not support initiation of integrin-dependent signaling cascades required for adhesion and subsequent lamellipodial extension, thereby causing a defect in early cell spreading. Coexpression of VASP with constitutively active mDia2(M/A) rescued these early adhesion defects. We conclude that Ena/VASP and mDia2 support the formation of filopodia with significantly distinct properties and that Ena/VASP regulates mDia2-initiated filopodial morphology, dynamics, and function.
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Affiliation(s)
- Melanie Barzik
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Leslie M McClain
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Frank B Gertler
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
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33
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Bilancia CG, Winkelman JD, Tsygankov D, Nowotarski SH, Sees JA, Comber K, Evans I, Lakhani V, Wood W, Elston TC, Kovar DR, Peifer M. Enabled negatively regulates diaphanous-driven actin dynamics in vitro and in vivo. Dev Cell 2014; 28:394-408. [PMID: 24576424 PMCID: PMC3992947 DOI: 10.1016/j.devcel.2014.01.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 12/20/2013] [Accepted: 01/15/2014] [Indexed: 11/03/2022]
Abstract
Actin regulators facilitate cell migration by controlling cell protrusion architecture and dynamics. As the behavior of individual actin regulators becomes clear, we must address why cells require multiple regulators with similar functions and how they cooperate to create diverse protrusions. We characterized Diaphanous (Dia) and Enabled (Ena) as a model, using complementary approaches: cell culture, biophysical analysis, and Drosophila morphogenesis. We found that Dia and Ena have distinct biochemical properties that contribute to the different protrusion morphologies each induces. Dia is a more processive, faster elongator, paralleling the long, stable filopodia it induces in vivo, while Ena promotes filopodia with more dynamic changes in number, length, and lifetime. Acting together, Ena and Dia induce protrusions distinct from those induced by either alone, with Ena reducing Dia-driven protrusion length and number. Consistent with this, EnaEVH1 binds Dia directly and inhibits DiaFH1FH2-mediated nucleation in vitro. Finally, Ena rescues hemocyte migration defects caused by activated Dia. Dia and Ena differ biochemically, promoting distinct filopodia dynamics Dia and Ena colocalization negatively regulates filopodia Ena’s EVH1 binds Dia’s FH1 and reduces Dia-driven filopodia and actin nucleation Ena rescues DiaΔDAD inhibition of hemocyte migration speed to wounds in vivo
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Affiliation(s)
- Colleen G Bilancia
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jonathan D Winkelman
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Denis Tsygankov
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Stephanie H Nowotarski
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jennifer A Sees
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Kate Comber
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Iwan Evans
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Vinal Lakhani
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Will Wood
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Timothy C Elston
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Mark Peifer
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Tsygankov D, Bilancia CG, Vitriol EA, Hahn KM, Peifer M, Elston TC. CellGeo: a computational platform for the analysis of shape changes in cells with complex geometries. ACTA ACUST UNITED AC 2014; 204:443-60. [PMID: 24493591 PMCID: PMC3912527 DOI: 10.1083/jcb.201306067] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The open source MATLAB application CellGeo is a user-friendly computational platform that allows simultaneous, automated tracking and analysis of dynamic changes in cell shape, including protrusions ranging from filopodia to lamellipodia to growth cones. Cell biologists increasingly rely on computer-aided image analysis, allowing them to collect precise, unbiased quantitative results. However, despite great progress in image processing and computer vision, current computational approaches fail to address many key aspects of cell behavior, including the cell protrusions that guide cell migration and drive morphogenesis. We developed the open source MATLAB application CellGeo, a user-friendly computational platform to allow simultaneous, automated tracking and analysis of dynamic changes in cell shape, including protrusions ranging from filopodia to lamellipodia. Our method maps an arbitrary cell shape onto a tree graph that, unlike traditional skeletonization algorithms, preserves complex boundary features. CellGeo allows rigorous but flexible definition and accurate automated detection and tracking of geometric features of interest. We demonstrate CellGeo’s utility by deriving new insights into (a) the roles of Diaphanous, Enabled, and Capping protein in regulating filopodia and lamellipodia dynamics in Drosophila melanogaster cells and (b) the dynamic properties of growth cones in catecholaminergic a–differentiated neuroblastoma cells.
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Affiliation(s)
- Denis Tsygankov
- Department of Pharmacology, 2 Department of Biology, and 3 Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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Liu L, Wu CF. Distinct effects of Abelson kinase mutations on myocytes and neurons in dissociated Drosophila embryonic cultures: mimicking of high temperature. PLoS One 2014; 9:e86438. [PMID: 24466097 PMCID: PMC3897706 DOI: 10.1371/journal.pone.0086438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/07/2013] [Indexed: 11/18/2022] Open
Abstract
Abelson tyrosine kinase (Abl) is known to regulate axon guidance, muscle development, and cell-cell interaction in vivo. The Drosophila primary culture system offers advantages in exploring the cellular mechanisms mediated by Abl with utilizing various experimental manipulations. Here we demonstrate that single-embryo cultures exhibit stage-dependent characteristics of cellular differentiation and developmental progression in neurons and myocytes, as well as nerve-muscle contacts. In particular, muscle development critically depends on the stage of dissociated embryos. In wild-type (WT) cultures derived from embryos before stage 12, muscle cells remained within cell clusters and were rarely detected. Interestingly, abundant myocytes were spotted in Abl mutant cultures, exhibiting enhanced myocyte movement and fusion, as well as neuron-muscle contacts even in cultures dissociated from younger, stage 10 embryos. Notably, Abl myocytes frequently displayed well-expanded lamellipodia. Conversely, Abl neurons were characterized with fewer large veil-like lamellipodia, but instead had increased numbers of filopodia and darker nodes along neurites. These distinct phenotypes were equally evident in both homo- and hetero-zygous cultures (Abl/Abl vs. Abl/+) of different alleles (Abl1 and Abl4) indicating dominant mutational effects. Strikingly, in WT cultures derived from stage 10 embryos, high temperature (HT) incubation promoted muscle migration and fusion, partially mimicking the advanced muscle development typical of Abl cultures. However, HT enhanced neuronal growth with increased numbers of enlarged lamellipodia, distinct from the characteristic Abl neuronal morphology. Intriguingly, HT incubation also promoted Abl lamellipodia expansion, with a much greater effect on nerve cells than muscle. Our results suggest that Abl is an essential regulator for myocyte and neuron development and that high-temperature incubation partially mimics the faster muscle development typical of Abl cultures. Despite the extensive alterations by Abl mutations, we observed myocyte fusion events and nerve-muscle contact formation between WT and Abl cells in mixed WT and Abl cultures derived from labeled embryos.
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Affiliation(s)
- Lijuan Liu
- Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
| | - Chun-Fang Wu
- Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, China
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
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Bogdan S, Schultz J, Grosshans J. Formin' cellular structures: Physiological roles of Diaphanous (Dia) in actin dynamics. Commun Integr Biol 2014; 6:e27634. [PMID: 24719676 PMCID: PMC3977921 DOI: 10.4161/cib.27634] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/21/2013] [Accepted: 12/23/2013] [Indexed: 01/06/2023] Open
Abstract
Members of the Diaphanous (Dia) protein family are key regulators of fundamental actin driven cellular processes, which are conserved from yeast to humans. Researchers have uncovered diverse physiological roles in cell morphology, cell motility, cell polarity, and cell division, which are involved in shaping cells into tissues and organs. The identification of numerous binding partners led to substantial progress in our understanding of the differential functions of Dia proteins. Genetic approaches and new microscopy techniques allow important new insights into their localization, activity, and molecular principles of regulation.
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Affiliation(s)
- Sven Bogdan
- Institut für Neurobiologie; Universität Münster; Münster, Germany
| | - Jörg Schultz
- Bioinformatik, Biozentrum; Universität Würzburg; Würzburg, Germany
| | - Jörg Grosshans
- Institut für Biochemie; Universitätsmedizin; Universität Göttingen; Göttingen, Germany
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37
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Roy S, Huang H, Liu S, Kornberg TB. Cytoneme-mediated contact-dependent transport of the Drosophila decapentaplegic signaling protein. Science 2014; 343:1244624. [PMID: 24385607 DOI: 10.1126/science.1244624] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Decapentaplegic (Dpp), a Drosophila morphogen signaling protein, transfers directly at synapses made at sites of contact between cells that produce Dpp and cytonemes that extend from recipient cells. The Dpp that cytonemes receive moves together with activated receptors toward the recipient cell body in motile puncta. Genetic loss-of-function conditions for diaphanous, shibire, neuroglian, and capricious perturbed cytonemes by reducing their number or only the synapses they make with cells they target, and reduced cytoneme-mediated transport of Dpp and Dpp signaling. These experiments provide direct evidence that cells use cytonemes to exchange signaling proteins, that cytoneme-based exchange is essential for signaling and normal development, and that morphogen distribution and signaling can be contact-dependent, requiring cytoneme synapses.
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Affiliation(s)
- Sougata Roy
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA
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38
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Starke J, Maaser K, Wehrle-Haller B, Friedl P. Mechanotransduction of mesenchymal melanoma cell invasion into 3D collagen lattices: Filopod-mediated extension–relaxation cycles and force anisotropy. Exp Cell Res 2013; 319:2424-33. [DOI: 10.1016/j.yexcr.2013.04.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/05/2013] [Indexed: 10/26/2022]
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39
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Rousso T, Shewan AM, Mostov KE, Schejter ED, Shilo BZ. Apical targeting of the formin Diaphanous in Drosophila tubular epithelia. eLife 2013; 2:e00666. [PMID: 23853710 PMCID: PMC3707080 DOI: 10.7554/elife.00666] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 06/03/2013] [Indexed: 12/12/2022] Open
Abstract
Apical secretion from epithelial tubes of the Drosophila embryo is mediated by apical F-actin cables generated by the formin-family protein Diaphanous (Dia). Apical localization and activity of Dia are at the core of restricting F-actin formation to the correct membrane domain. Here we identify the mechanisms that target Dia to the apical surface. PI(4,5)P2 levels at the apical membrane regulate Dia localization in both the MDCK cyst model and in Drosophila tubular epithelia. An N-terminal basic domain of Dia is crucial for apical localization, implying direct binding to PI(4,5)P2. Dia apical targeting also depends on binding to Rho1, which is critical for activation-induced conformational change, as well as physically anchoring Dia to the apical membrane. We demonstrate that binding to Rho1 facilitates interaction with PI(4,5)P2 at the plane of the membrane. Together these cues ensure efficient and distinct restriction of Dia to the apical membrane. DOI:http://dx.doi.org/10.7554/eLife.00666.001.
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Affiliation(s)
- Tal Rousso
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Annette M Shewan
- Department of Anatomy, University of California, San Francisco, San Francisco, United States
| | - Keith E Mostov
- Department of Anatomy, University of California, San Francisco, San Francisco, United States
| | - Eyal D Schejter
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ben-Zion Shilo
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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40
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Pickering K, Alves-Silva J, Goberdhan D, Millard TH. Par3/Bazooka and phosphoinositides regulate actin protrusion formation during Drosophila dorsal closure and wound healing. Development 2013; 140:800-9. [PMID: 23318638 DOI: 10.1242/dev.089557] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Effective wound closure mechanisms are essential for maintenance of epithelial structure and function. The repair of wounded epithelia is primarily driven by the cells bordering the wound, which become motile after wounding, forming dynamic actin protrusions along the wound edge. The molecular mechanisms that trigger wound edge cells to become motile following tissue damage are not well understood. Using wound healing and dorsal closure in Drosophila, we identify a direct molecular link between changes in cell-cell adhesion at epithelial edges and induction of actin protrusion formation. We find that the scaffolding protein Par3/Bazooka and the lipid phosphatase Pten are specifically lost from cell-cell junctions at epithelial edges. This results in a localized accumulation of phosphatidylinositol 3,4,5-trisphosphate (PIP3), which promotes the formation of actin protrusions along the epithelial edge. Depleting PIP3 results in defective epithelial closure during both dorsal closure and wound healing. These data reveal a novel mechanism that directly couples loss of epithelial integrity to activation of epithelial closure.
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Affiliation(s)
- Karen Pickering
- The Healing Foundation Centre, Faculty of Life Sciences, University of Manchester, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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41
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Sano H, Kunwar PS, Renault AD, Barbosa V, Clark IBN, Ishihara S, Sugimura K, Lehmann R. The Drosophila actin regulator ENABLED regulates cell shape and orientation during gonad morphogenesis. PLoS One 2012; 7:e52649. [PMID: 23300733 PMCID: PMC3530444 DOI: 10.1371/journal.pone.0052649] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/16/2012] [Indexed: 12/27/2022] Open
Abstract
Organs develop distinctive morphologies to fulfill their unique functions. We used Drosophila embryonic gonads as a model to study how two different cell lineages, primordial germ cells (PGCs) and somatic gonadal precursors (SGPs), combine to form one organ. We developed a membrane GFP marker to image SGP behaviors live. These studies show that a combination of SGP cell shape changes and inward movement of anterior and posterior SGPs leads to the compaction of the spherical gonad. This process is disrupted in mutants of the actin regulator, enabled (ena). We show that Ena coordinates these cell shape changes and the inward movement of the SGPs, and Ena affects the intracellular localization of DE-cadherin (DE-cad). Mathematical simulation based on these observations suggests that changes in DE-cad localization can generate the forces needed to compact an elongated structure into a sphere. We propose that Ena regulates force balance in the SGPs by sequestering DE-cad, leading to the morphogenetic movement required for gonad compaction.
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Affiliation(s)
- Hiroko Sano
- HHMI and Developmental Genetics Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University Medical Center, New York, New York, United States of America.
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42
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Gupton SL, Riquelme D, Hughes-Alford SK, Tadros J, Rudina SS, Hynes RO, Lauffenburger D, Gertler FB. Mena binds α5 integrin directly and modulates α5β1 function. ACTA ACUST UNITED AC 2012; 198:657-76. [PMID: 22908313 PMCID: PMC3514034 DOI: 10.1083/jcb.201202079] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mena binds to the cytoplasmic tail of α5 integrin and modulates key
α5β1 integrin functions in adhesion, motility, and
fibrillogenesis. Mena is an Ena/VASP family actin regulator with roles in cell migration,
chemotaxis, cell–cell adhesion, tumor cell invasion, and metastasis.
Although enriched in focal adhesions, Mena has no established function within
these structures. We find that Mena forms an adhesion-regulated complex with
α5β1 integrin, a fibronectin receptor involved in cell adhesion,
motility, fibronectin fibrillogenesis, signaling, and growth factor receptor
trafficking. Mena bound directly to the carboxy-terminal portion of the
α5 cytoplasmic tail via a 91-residue region containing 13 five-residue
“LERER” repeats. In fibroblasts, the Mena–α5 complex
was required for “outside-in” α5β1 functions,
including normal phosphorylation of FAK and paxillin and formation of fibrillar
adhesions. It also supported fibrillogenesis and cell spreading and controlled
cell migration speed. Thus, fibroblasts require Mena for multiple
α5β1-dependent processes involving bidirectional interactions
between the extracellular matrix and cytoplasmic focal adhesion proteins.
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Affiliation(s)
- Stephanie L Gupton
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Peng Y, Han C, Axelrod JD. Planar polarized protrusions break the symmetry of EGFR signaling during Drosophila bract cell fate induction. Dev Cell 2012; 23:507-18. [PMID: 22921201 DOI: 10.1016/j.devcel.2012.07.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 04/12/2012] [Accepted: 07/20/2012] [Indexed: 01/06/2023]
Abstract
Secreted signaling molecules typically float in the outer leaflet of the plasma membrane or freely diffuse away from the signaling cell, suggesting that a signal should be sensed equally by all neighboring cells. However, we demonstrate that Spitz (Spi)-mediated epidermal growth factor receptor (EGFR) signaling is spatially biased to selectively determine the induction of a single bract cell on the proximal side of each mechanosensory organ on the Drosophila leg. Dynamic and oriented cellular protrusions emanating from the socket cell, the source of Spi, robustly favor the Spi/EGFR signaling response in a particular cell among equally competent neighbors. We propose that these protrusive structures enhance signaling by increasing contact between the signaling and responding cells. The planar polarized direction of the protrusions determines the direction of the signaling outcome. This asymmetric cell signaling serves as a developmental mechanism to generate spatially patterned cell fates.
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Affiliation(s)
- Ying Peng
- Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
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44
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Anhezini L, Saita AP, Costa MS, Ramos RGP, Simon CR. Fhosencodes aDrosophilaFormin-Like Protein participating in autophagic programmed cell death. Genesis 2012; 50:672-84. [DOI: 10.1002/dvg.22025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 03/01/2012] [Accepted: 03/05/2012] [Indexed: 01/12/2023]
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45
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Control of dendritic morphogenesis by Trio in Drosophila melanogaster. PLoS One 2012; 7:e33737. [PMID: 22438988 PMCID: PMC3305316 DOI: 10.1371/journal.pone.0033737] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/16/2012] [Indexed: 11/19/2022] Open
Abstract
Abl tyrosine kinase and its effectors among the Rho family of GTPases each act to control dendritic morphogenesis in Drosophila. It has not been established, however, which of the many GTPase regulators in the cell link these signaling molecules in the dendrite. In axons, the bifunctional guanine exchange factor, Trio, is an essential link between the Abl tyrosine kinase signaling pathway and Rho GTPases, particularly Rac, allowing these systems to act coordinately to control actin organization. In dendritic morphogenesis, however, Abl and Rac have contrary rather than reinforcing effects, raising the question of whether Trio is involved, and if so, whether it acts through Rac, Rho or both. We now find that Trio is expressed in sensory neurons of the Drosophila embryo and regulates their dendritic arborization. trio mutants display a reduction in dendritic branching and increase in average branch length, whereas over-expression of trio has the opposite effect. We further show that it is the Rac GEF domain of Trio, and not its Rho GEF domain that is primarily responsible for the dendritic function of Trio. Thus, Trio shapes the complexity of dendritic arbors and does so in a way that mimics the effects of its target, Rac.
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46
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Varghese M, Gorsevski P, Cayer ML, Boudreau NS, Heckman CA. Unraveling the determinants of protrusion formation. Int J Cell Biol 2012; 2012:402916. [PMID: 22500172 PMCID: PMC3303863 DOI: 10.1155/2012/402916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 10/26/2011] [Indexed: 01/13/2023] Open
Abstract
A COMPUTERIZED MORPHOMETRIC CLASSIFICATION TECHNIQUE BASED ON LATENT FACTORS REVEALS MAJOR PROTRUSION CLASSES: factors 4, 5, and 7. Previous work showed that factor 4 represented filopodia, 5 the distribution of lamellar cytoplasm, and 7 a blunt protrusion. We explore the relationship of focal contact (FC) characteristics and their integrated actin cables to factors values. The results show that FC maturation/cytoskeletal integration affects factor 5, because FC elongation/integration was correlated with its values. On the contrary, 7 values decreased with maturation, so cable or FC size or their integration must be restricted to form these protrusions. Where integration did occur, the cables showed distinctive size and orientation, as indicated by correlation of 7 values with FC shape. Results obtained with myosin inhibitors support the interpretation that a central, isometric, contractile network puts constraints on both factor 5 and 7 protrusions. We conclude that cells establish functional domains by rearranging the cytoskeleton.
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Affiliation(s)
- Mita Varghese
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403-0212, USA
| | - Peter Gorsevski
- School of Earth, Environment and Society, Bowling Green State University, Bowling Green, OH 43403-0212, USA
| | - Marilyn L. Cayer
- Center for Microscopy and Microanalysis, Bowling Green State University, Bowling Green, OH 43403-0212, USA
| | - Nancy S. Boudreau
- Department of Applied Statistics and Operations Research, Bowling Green State University, Bowling Green, OH 43403-0212, USA
| | - Carol A. Heckman
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403-0212, USA
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Takahashi K, Suzuki K. WAVE2, N-WASP, and Mena facilitate cell invasion via phosphatidylinositol 3-kinase-dependent local accumulation of actin filaments. J Cell Biochem 2012; 112:3421-9. [PMID: 21769917 DOI: 10.1002/jcb.23276] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cell migration is accomplished by the formation of cellular protrusions such as lamellipodia and filopodia. These protrusions result from actin filament (F-actin) rearrangement at the cell cortex by WASP/WAVE family proteins and Drosophila enabled (Ena)/vasodilator-stimulated factor proteins. However, the role of each of these actin cytoskeletal regulatory proteins in the regulation of three-dimensional cell invasion remains to be clarified. We found that platelet-derived growth factor (PDGF) induces invasion of MDA-MB-231 human breast cancer cells through invasion chamber membrane pores. This invasion was accompanied by intensive F-actin accumulation at the sites of cell infiltration. After PDGF stimulation, WAVE2, N-WASP, and a mammalian Ena (Mena) colocalized with F-actin at the sites of cell infiltration in a phosphatidylinositol 3-kinase (PI3K)-dependent manner. Depletion of WAVE2, N-WASP, or Mena by RNA interference (RNAi) abrogated both cell invasion and intensive F-actin accumulation at the invasion site. These results indicate that by mediating intensive F-actin accumulation at the sites of cell infiltration, WAVE2, N-WASP, and Mena are crucial for PI3K-dependent cell invasion induced by PDGF.
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Affiliation(s)
- Kazuhide Takahashi
- Molecular Cell Biology Division, Kanagawa Cancer Center Research Institute, Yokohama 241-0815, Japan.
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48
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Yang C, Svitkina T. Filopodia initiation: focus on the Arp2/3 complex and formins. Cell Adh Migr 2012; 5:402-8. [PMID: 21975549 DOI: 10.4161/cam.5.5.16971] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Filopodia are long, slender, actin-rich cellular protrusions, which recently have become a focus of cell biology research because of their proposed roles as sensory and exploratory organelles that allow for "intelligent" cell behavior. Actin nucleation, elongation and bundling are believed to be essential for filopodia formation and functions. However, the identity of actin filament nucleators responsible for the initiation of filopodia remains controversial. Two alternative models, the convergent elongation and tip nucleation, emphasize two different actin filament nucleators, the Arp2/3 complex or formins, respectively, as key players during filopodia initiation. Although these two models in principle are not mutually exclusive, it is important to understand which of them is actually employed by cells. In this review, we discuss the existing evidence regarding the relative roles of the Arp2/3 complex and formins in filopodia initiation.
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Affiliation(s)
- Changsong Yang
- Department of Biology; University of Pennsylvania; Philadelphia, PA, USA
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49
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Heckman C, Varghese M, Cayer M, Boudreau NS. Origin of ruffles: Linkage to other protrusions, filopodia and lamellae. Cell Signal 2012; 24:189-98. [DOI: 10.1016/j.cellsig.2011.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Accepted: 08/28/2011] [Indexed: 10/17/2022]
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50
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Harris TJ. Adherens Junction Assembly and Function in the Drosophila Embryo. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 293:45-83. [DOI: 10.1016/b978-0-12-394304-0.00007-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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