1
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Ahangar P, Cowin AJ. Reforming the Barrier: The Role of Formins in Wound Repair. Cells 2022; 11:cells11182779. [PMID: 36139355 PMCID: PMC9496773 DOI: 10.3390/cells11182779] [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: 08/19/2022] [Revised: 09/02/2022] [Accepted: 09/02/2022] [Indexed: 12/04/2022] Open
Abstract
The restoration of an intact epidermal barrier after wound injury is the culmination of a highly complex and exquisitely regulated physiological process involving multiple cells and tissues, overlapping dynamic events and protein synthesis and regulation. Central to this process is the cytoskeleton, a system of intracellular proteins that are instrumental in regulating important processes involved in wound repair including chemotaxis, cytokinesis, proliferation, migration, and phagocytosis. One highly conserved family of cytoskeletal proteins that are emerging as major regulators of actin and microtubule nucleation, polymerization, and stabilization are the formins. The formin family includes 15 different proteins categorized into seven subfamilies based on three formin homology domains (FH1, FH2, and FH3). The formins themselves are regulated in different ways including autoinhibition, activation, and localization by a range of proteins, including Rho GTPases. Herein, we describe the roles and effects of the formin family of cytoskeletal proteins on the fundamental process of wound healing and highlight recent advances relating to their important functions, mechanisms, and regulation at the molecular and cellular levels.
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2
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Ahangar P, Strudwick XL, Cowin AJ. Wound Healing from an Actin Cytoskeletal Perspective. Cold Spring Harb Perspect Biol 2022; 14:a041235. [PMID: 35074864 PMCID: PMC9341468 DOI: 10.1101/cshperspect.a041235] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Wound healing requires a complex cascade of highly controlled and conserved cellular and molecular processes. These involve numerous cell types and extracellular matrix molecules regulated by the actin cytoskeleton. This microscopic network of filaments is present within the cytoplasm of all cells and provides the shape and mechanical support required for cell movement and proliferation. Here, an overview of the processes of wound healing are described from the perspective of the cell in relation to the actin cytoskeleton. Key points of discussion include the role of actin, its binding proteins, signaling pathways, and events that play significant roles in the phases of wound healing. The identification of cytoskeletal targets that can be used to manipulate and improve wound healing is included as an emerging area of focus that may inform future therapeutic approaches to improve healing of complex wounds.
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Affiliation(s)
- Parinaz Ahangar
- Future Industries Institute, UniSA STEM, University of South Australia, South Australia, Adelaide 5000, Australia
| | - Xanthe L Strudwick
- Future Industries Institute, UniSA STEM, University of South Australia, South Australia, Adelaide 5000, Australia
| | - Allison J Cowin
- Future Industries Institute, UniSA STEM, University of South Australia, South Australia, Adelaide 5000, Australia
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3
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Valencia FR, Sandoval E, Du J, Iu E, Liu J, Plotnikov SV. Force-dependent activation of actin elongation factor mDia1 protects the cytoskeleton from mechanical damage and promotes stress fiber repair. Dev Cell 2021; 56:3288-3302.e5. [PMID: 34822787 DOI: 10.1016/j.devcel.2021.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 08/02/2021] [Accepted: 11/02/2021] [Indexed: 01/16/2023]
Abstract
Plasticity of cell mechanics underlies a wide range of cell and tissue behaviors allowing cells to migrate through narrow spaces, resist shear forces, and safeguard against mechanical damage. Such plasticity depends on spatiotemporal regulation of the actomyosin cytoskeleton, but mechanisms of adaptive change in cell mechanics remain elusive. Here, we report a mechanism of mechanically activated actin polymerization at focal adhesions (FAs), specifically requiring the actin elongation factor mDia1. By combining live-cell imaging with mathematical modeling, we show that actin polymerization at FAs exhibits pulsatile dynamics where spikes of mDia1 activity are triggered by contractile forces. The suppression of mDia1-mediated actin polymerization increases tension on stress fibers (SFs) leading to an increased frequency of spontaneous SF damage and decreased efficiency of zyxin-mediated SF repair. We conclude that tension-controlled actin polymerization acts as a safety valve dampening excessive tension on the actin cytoskeleton and safeguarding SFs against mechanical damage.
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Affiliation(s)
- Fernando R Valencia
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Eduardo Sandoval
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Joy Du
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Ernest Iu
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Jian Liu
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Sergey V Plotnikov
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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4
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The actin polymerization factor Diaphanous and the actin severing protein Flightless I collaborate to regulate sarcomere size. Dev Biol 2021; 469:12-25. [PMID: 32980309 DOI: 10.1016/j.ydbio.2020.09.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 09/15/2020] [Accepted: 09/19/2020] [Indexed: 12/22/2022]
Abstract
The sarcomere is the basic contractile unit of muscle, composed of repeated sets of actin thin filaments and myosin thick filaments. During muscle development, sarcomeres grow in size to accommodate the growth and function of muscle fibers. Failure in regulating sarcomere size results in muscle dysfunction; yet, it is unclear how the size and uniformity of sarcomeres are controlled. Here we show that the formin Diaphanous is critical for the growth and maintenance of sarcomere size: Dia sets sarcomere length and width through regulation of the number and length of the actin thin filaments in the Drosophila flight muscle. To regulate thin filament length and sarcomere size, Dia interacts with the Gelsolin superfamily member Flightless I (FliI). We suggest that these actin regulators, by controlling actin dynamics and turnover, generate uniformly sized sarcomeres tuned for the muscle contractions required for flight.
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5
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Strudwick XL, Cowin AJ. Multifunctional Roles of the Actin-Binding Protein Flightless I in Inflammation, Cancer and Wound Healing. Front Cell Dev Biol 2020; 8:603508. [PMID: 33330501 PMCID: PMC7732498 DOI: 10.3389/fcell.2020.603508] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 10/30/2020] [Indexed: 11/20/2022] Open
Abstract
Flightless I is an actin-binding member of the gelsolin family of actin-remodeling proteins that inhibits actin polymerization but does not possess actin severing ability. Flightless I functions as a regulator of many cellular processes including proliferation, differentiation, apoptosis, and migration all of which are important for many physiological processes including wound repair, cancer progression and inflammation. More than simply facilitating cytoskeletal rearrangements, Flightless I has other important roles in the regulation of gene transcription within the nucleus where it interacts with nuclear hormone receptors to modulate cellular activities. In conjunction with key binding partners Leucine rich repeat in the Flightless I interaction proteins (LRRFIP)1/2, Flightless I acts both synergistically and competitively to regulate a wide range of cellular signaling including interacting with two of the most important inflammatory pathways, the NLRP3 inflammasome and the MyD88-TLR4 pathways. In this review we outline the current knowledge about this important cytoskeletal protein and describe its many functions across a range of health conditions and pathologies. We provide perspectives for future development of Flightless I as a potential target for clinical translation and insights into potential therapeutic approaches to manipulate Flightless I functions.
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Affiliation(s)
- Xanthe L Strudwick
- Regenerative Medicine, Future Industries Institute, University of South Australia, Mawson Lakes, SA, Australia
| | - Allison J Cowin
- Regenerative Medicine, Future Industries Institute, University of South Australia, Mawson Lakes, SA, Australia
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6
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Pintér R, Huber T, Bukovics P, Gaszler P, Vig AT, Tóth MÁ, Gazsó-Gerhát G, Farkas D, Migh E, Mihály J, Bugyi B. The Activities of the Gelsolin Homology Domains of Flightless-I in Actin Dynamics. Front Mol Biosci 2020; 7:575077. [PMID: 33033719 PMCID: PMC7509490 DOI: 10.3389/fmolb.2020.575077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/14/2020] [Indexed: 12/12/2022] Open
Abstract
Flightless-I is a unique member of the gelsolin superfamily alloying six gelsolin homology domains and leucine-rich repeats. Flightless-I is an established regulator of the actin cytoskeleton, however, its biochemical activities in actin dynamics are still largely elusive. To better understand the biological functioning of Flightless-I we studied the actin activities of Drosophila Flightless-I by in vitro bulk fluorescence spectroscopy and single filament fluorescence microscopy, as well as in vivo genetic approaches. Flightless-I was found to interact with actin and affects actin dynamics in a calcium-independent fashion in vitro. Our work identifies the first three gelsolin homology domains (1–3) of Flightless-I as the main actin-binding site; neither the other three gelsolin homology domains (4–6) nor the leucine-rich repeats bind actin. Flightless-I inhibits polymerization by high-affinity (∼nM) filament barbed end capping, moderately facilitates nucleation by low-affinity (∼μM) monomer binding, and does not sever actin filaments. Our work reveals that in the presence of profilin Flightless-I is only able to cap actin filament barbed ends but fails to promote actin assembly. In line with the in vitro data, while gelsolin homology domains 4–6 have no effect on in vivo actin polymerization, overexpression of gelsolin homology domains 1–3 prevents the formation of various types of actin cables in the developing Drosophila egg chambers. We also show that the gelsolin homology domains 4–6 of Flightless-I interact with the C-terminus of Drosophila Disheveled-associated activator of morphogenesis formin and negatively regulates its actin assembly activity.
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Affiliation(s)
- Réka Pintér
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Tamás Huber
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Bukovics
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Gaszler
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Andrea Teréz Vig
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Mónika Ágnes Tóth
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary
| | - Gabriella Gazsó-Gerhát
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary.,Faculty of Science and Informatics, Doctoral School in Biology, University of Szeged, Szeged, Hungary
| | - Dávid Farkas
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary
| | - Ede Migh
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary
| | - József Mihály
- Biological Research Centre Szeged, Institute of Genetics, Szeged, Hungary
| | - Beáta Bugyi
- Department of Biophysics, Medical School, University of Pécs, Pécs, Hungary.,Szentágothai Research Center, Pécs, Hungary
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7
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Szikora S, Gajdos T, Novák T, Farkas D, Földi I, Lenart P, Erdélyi M, Mihály J. Nanoscopy reveals the layered organization of the sarcomeric H-zone and I-band complexes. J Cell Biol 2020; 219:132617. [PMID: 31816054 PMCID: PMC7039190 DOI: 10.1083/jcb.201907026] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 10/04/2019] [Accepted: 10/22/2019] [Indexed: 01/18/2023] Open
Abstract
Sarcomeres are extremely highly ordered macromolecular assemblies where structural organization is intimately linked to their functionality as contractile units. Although the structural basis of actin and Myosin interaction is revealed at a quasiatomic resolution, much less is known about the molecular organization of the I-band and H-zone. We report the development of a powerful nanoscopic approach, combined with a structure-averaging algorithm, that allowed us to determine the position of 27 sarcomeric proteins in Drosophila melanogaster flight muscles with a quasimolecular, ∼5- to 10-nm localization precision. With this protein localization atlas and template-based protein structure modeling, we have assembled refined I-band and H-zone models with unparalleled scope and resolution. In addition, we found that actin regulatory proteins of the H-zone are organized into two distinct layers, suggesting that the major place of thin filament assembly is an M-line-centered narrow domain where short actin oligomers can form and subsequently anneal to the pointed end.
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Affiliation(s)
- Szilárd Szikora
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Tamás Gajdos
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Tibor Novák
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - Dávid Farkas
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - István Földi
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Peter Lenart
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Miklós Erdélyi
- Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
| | - József Mihály
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.,Department of Optics and Quantum Electronics, University of Szeged, Szeged, Hungary
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8
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Cao L, Yonis A, Vaghela M, Barriga EH, Chugh P, Smith MB, Maufront J, Lavoie G, Méant A, Ferber E, Bovellan M, Alberts A, Bertin A, Mayor R, Paluch EK, Roux PP, Jégou A, Romet-Lemonne G, Charras G. SPIN90 associates with mDia1 and the Arp2/3 complex to regulate cortical actin organization. Nat Cell Biol 2020; 22:803-814. [PMID: 32572169 DOI: 10.1038/s41556-020-0531-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/04/2020] [Indexed: 01/02/2023]
Abstract
Cell shape is controlled by the submembranous cortex, an actomyosin network mainly generated by two actin nucleators: the Arp2/3 complex and the formin mDia1. Changes in relative nucleator activity may alter cortical organization, mechanics and cell shape. Here we investigate how nucleation-promoting factors mediate interactions between nucleators. In vitro, the nucleation-promoting factor SPIN90 promotes formation of unbranched filaments by Arp2/3, a process thought to provide the initial filament for generation of dendritic networks. Paradoxically, in cells, SPIN90 appears to favour a formin-dominated cortex. Our in vitro experiments reveal that this feature stems mainly from two mechanisms: efficient recruitment of mDia1 to SPIN90-Arp2/3 nucleated filaments and formation of a ternary SPIN90-Arp2/3-mDia1 complex that greatly enhances filament nucleation. Both mechanisms yield rapidly elongating filaments with mDia1 at their barbed ends and SPIN90-Arp2/3 at their pointed ends. Thus, in networks, SPIN90 lowers branching densities and increases the proportion of long filaments elongated by mDia1.
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Affiliation(s)
- Luyan Cao
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Amina Yonis
- London Centre for Nanotechnology, University College London, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK
| | - Malti Vaghela
- London Centre for Nanotechnology, University College London, London, UK.,Department of Physics and Astronomy, University College London, London, UK
| | - Elias H Barriga
- Department of Cell and Developmental Biology, University College London, London, UK.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Priyamvada Chugh
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Matthew B Smith
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK.,The Francis Crick institute, London, UK
| | - Julien Maufront
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Universités, Paris, France
| | - Geneviève Lavoie
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada
| | - Antoine Méant
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada
| | - Emma Ferber
- London Centre for Nanotechnology, University College London, London, UK
| | - Miia Bovellan
- London Centre for Nanotechnology, University College London, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK
| | - Art Alberts
- Van Andel research institute, Grand Rapids, MI, USA
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Universités, Paris, France
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Ewa K Paluch
- MRC-Laboratory for Molecular Cell Biology, University College London, London, UK.,Institute for the Physics of Living Systems, University College London, London, UK.,Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Quebec, Canada.,Department of Pathology and Cell Biology, Université de Montréal, Montréal, Canada
| | - Antoine Jégou
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France.
| | | | - Guillaume Charras
- London Centre for Nanotechnology, University College London, London, UK. .,Department of Cell and Developmental Biology, University College London, London, UK. .,Institute for the Physics of Living Systems, University College London, London, UK.
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9
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Nakaya MA, Gudmundsson KO, Komiya Y, Keller JR, Habas R, Yamaguchi TP, Ajima R. Placental defects lead to embryonic lethality in mice lacking the Formin and PCP proteins Daam1 and Daam2. PLoS One 2020; 15:e0232025. [PMID: 32353019 PMCID: PMC7192421 DOI: 10.1371/journal.pone.0232025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 04/06/2020] [Indexed: 01/30/2023] Open
Abstract
The actin cytoskeleton plays a central role in establishing cell polarity and shape during embryonic morphogenesis. Daam1, a member of the Formin family of actin cytoskeleton regulators, is a Dvl2-binding protein that functions in the Wnt/Planar Cell Polarity (PCP) pathway. To examine the role of the Daam proteins in mammalian development, we generated Daam-deficient mice by gene targeting and found that Daam1, but not Daam2, is necessary for fetal survival. Embryonic development of Daam1 mutants was delayed most likely due to functional defects in the labyrinthine layer of the placenta. Examination of Daam2 and Daam1/2 double mutants revealed that Daam1 and Daam2 are functionally redundant during placental development. Of note, neural tube closure defects (NTD), which are observed in several mammalian PCP mutants, are not observed in Wnt5a or Daam1 single mutants, but arise in Daam1;Wnt5a double mutants. These findings demonstrate a unique function for Daam genes in placental development and are consistent with a role for Daam1 in the Wnt/PCP pathway in mammals.
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Affiliation(s)
- Masa-aki Nakaya
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland, United State of America
| | - Kristibjorn Orri Gudmundsson
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland, United State of America
| | - Yuko Komiya
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United State of America
| | - Jonathan R. Keller
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland, United State of America
| | - Raymond Habas
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United State of America
| | - Terry P. Yamaguchi
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland, United State of America
| | - Rieko Ajima
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, Maryland, United State of America
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10
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Chougule A, Lapraz F, Földi I, Cerezo D, Mihály J, Noselli S. The Drosophila actin nucleator DAAM is essential for left-right asymmetry. PLoS Genet 2020; 16:e1008758. [PMID: 32324733 PMCID: PMC7200016 DOI: 10.1371/journal.pgen.1008758] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 05/05/2020] [Accepted: 04/05/2020] [Indexed: 12/14/2022] Open
Abstract
Left-Right (LR) asymmetry is essential for organ positioning, shape and function. Myosin 1D (Myo1D) has emerged as an evolutionary conserved chirality determinant in both Drosophila and vertebrates. However, the molecular interplay between Myo1D and the actin cytoskeleton underlying symmetry breaking remains poorly understood. To address this question, we performed a dual genetic screen to identify new cytoskeletal factors involved in LR asymmetry. We identified the conserved actin nucleator DAAM as an essential factor required for both dextral and sinistral development. In the absence of DAAM, organs lose their LR asymmetry, while its overexpression enhances Myo1D-induced de novo LR asymmetry. These results show that DAAM is a limiting, LR-specific actin nucleator connecting up Myo1D with a dedicated F-actin network important for symmetry breaking. Although our body looks symmetrical when viewed from the outside, it is in fact highly asymmetrical when we consider the shape and implantation of organs. For example, our heart is on the left side of the thorax, while the liver is on the right. In addition, our heart is made up of two distinct parts, the right heart and the left heart, which play different roles for blood circulation. These asymmetries, called left-right asymmetries, play a fundamental role in the morphogenesis and function of visceral organs and the brain. Aberrant LR asymmetry in human results in severe anatomical defects leading to embryonic lethality, spontaneous abortion and a number of congenital disorders. Our recent work has identified a particular myosin (Myo1D) as a major player in asymmetry in Drosophila and vertebrates. Myosins are proteins that can interact with the skeleton of cells (called the cytoskeleton) to transport other proteins, contract the cells, allow them to move, etc. In this work, we were able to identify all the genes of the cytoskeleton involved with myosin in left-right asymmetry, in particular a so-called 'nucleator' gene because it is capable of forming new parts of the cytoskeleton necessary for setting up asymmetries.
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Affiliation(s)
- Anil Chougule
- Université Côte D’Azur, CNRS, Inserm, iBV, Nice, France
| | | | - István Földi
- Biological Research Centre, Hungarian Academy of Sciences, Institute of Genetics, Hungary
| | | | - József Mihály
- Biological Research Centre, Hungarian Academy of Sciences, Institute of Genetics, Hungary
| | - Stéphane Noselli
- Université Côte D’Azur, CNRS, Inserm, iBV, Nice, France
- * E-mail:
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11
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Chen A, Arora PD, Lai CC, Copeland JW, Moraes TF, McCulloch CA, Lavoie BD, Wilde A. The scaffold-protein IQGAP1 enhances and spatially restricts the actin-nucleating activity of Diaphanous-related formin 1 (DIAPH1). J Biol Chem 2020; 295:3134-3147. [PMID: 32005666 DOI: 10.1074/jbc.ra119.010476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/24/2020] [Indexed: 11/06/2022] Open
Abstract
The actin cytoskeleton is a dynamic array of filaments that undergoes rapid remodeling to drive many cellular processes. An essential feature of filament remodeling is the spatio-temporal regulation of actin filament nucleation. One family of actin filament nucleators, the Diaphanous-related formins, is activated by the binding of small G-proteins such as RhoA. However, RhoA only partially activates formins, suggesting that additional factors are required to fully activate the formin. Here we identify one such factor, IQ motif containing GTPase activating protein-1 (IQGAP1), which enhances RhoA-mediated activation of the Diaphanous-related formin (DIAPH1) and targets DIAPH1 to the plasma membrane. We find that the inhibitory intramolecular interaction within DIAPH1 is disrupted by the sequential binding of RhoA and IQGAP1. Binding of RhoA and IQGAP1 robustly stimulates DIAPH1-mediated actin filament nucleation in vitro In contrast, the actin capping protein Flightless-I, in conjunction with RhoA, only weakly stimulates DIAPH1 activity. IQGAP1, but not Flightless-I, is required to recruit DIAPH1 to the plasma membrane where actin filaments are generated. These results indicate that IQGAP1 enhances RhoA-mediated activation of DIAPH1 in vivo Collectively these data support a model where the combined action of RhoA and an enhancer ensures the spatio-temporal regulation of actin nucleation to stimulate robust and localized actin filament production in vivo.
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Affiliation(s)
- Anan Chen
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Pam D Arora
- Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Christine C Lai
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - John W Copeland
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | | | - Brigitte D Lavoie
- Department Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada
| | - Andrew Wilde
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1M1, Canada; Department Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada.
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12
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Jiang T, Harris TJC. Par-1 controls the composition and growth of cortical actin caps during Drosophila embryo cleavage. J Cell Biol 2019; 218:4195-4214. [PMID: 31641019 PMCID: PMC6891076 DOI: 10.1083/jcb.201903152] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 08/21/2019] [Accepted: 09/22/2019] [Indexed: 11/22/2022] Open
Abstract
The cell cortex is populated by various proteins, but it is unclear how they interact to change cell shape. Jiang and Harris find that the kinase Par-1 is required for Diaphanous-based actin bundles, and that these bundles intersperse with separately induced Arp2/3 networks to form an actin cap that grows into a metaphase compartment of the syncytial Drosophila embryo. Cell structure depends on the cortex, a thin network of actin polymers and additional proteins underlying the plasma membrane. The cell polarity kinase Par-1 is required for cells to form following syncytial Drosophila embryo development. This requirement stems from Par-1 promoting cortical actin caps that grow into dome-like metaphase compartments for dividing syncytial nuclei. We find the actin caps to be a composite material of Diaphanous (Dia)-based actin bundles interspersed with independently formed, Arp2/3-based actin puncta. Par-1 and Dia colocalize along extended regions of the bundles, and both are required for the bundles and for each other’s bundle-like localization, consistent with an actin-dependent self-reinforcement mechanism. Par-1 helps establish or maintain these bundles in a cortical domain with relatively low levels of the canonical formin activator Rho1-GTP. Arp2/3 is required for displacing the bundles away from each other and toward the cap circumference, suggesting interactions between these cytoskeletal components could contribute to the growth of the cap into a metaphase compartment.
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Affiliation(s)
- Tao Jiang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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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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Arora PD, He T, Ng K, McCulloch CA. The leucine-rich region of Flightless I interacts with R-ras to regulate cell extension formation. Mol Biol Cell 2018; 29:2481-2493. [PMID: 30091651 PMCID: PMC6233052 DOI: 10.1091/mbc.e18-03-0147] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Flightless I (FliI) is a calcium-dependent, actin severing and capping protein that localizes to cell matrix adhesions, contributes to the generation of cell extensions, and colocalizes with Ras. Currently, the mechanism by which FliI interacts with Ras to enable assembly of actin-based cell protrusions is not defined. R-Ras, but not K-ras, H-ras, or N-ras, associated with the leucine-rich region (LRR) of FliI. Mutations of the proline-rich region of R-ras (P202A, P203A) prevented this association. Knockdown of Ras GTPase-activating SH3 domain-binding protein (G3BP1) or Rasgap120 by small interfering RNA inhibited the formation of cell extensions and prevented interaction of R-ras and G3BP1 in FliI wild-type (WT) cells. Pull-down assays using G3BP1 fusion proteins showed a strong association of R-ras with the C-terminus of G3BP1 (amino acids 236-466), which also required the LRR of FliI. In cells that expressed the truncated N-terminus or C-terminus of G3BP1, the formation of cell extensions was blocked. Endogenous Rasgap120 interacted with the N-terminus of G3BP1 (amino acids 1-230). We conclude that in cells plated on collagen FliI-LRR interacts with R-ras to promote cell extension formation and that FliI is required for the interaction of Rasgap120 with G3BP1 to regulate R-ras activity and growth of cell extensions.
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Affiliation(s)
- P D Arora
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - T He
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - K Ng
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - C A McCulloch
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 1A1, Canada
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15
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Silkworth WT, Kunes KL, Nickel GC, Phillips ML, Quinlan ME, Vizcarra CL. The neuron-specific formin Delphilin nucleates nonmuscle actin but does not enhance elongation. Mol Biol Cell 2017; 29:610-621. [PMID: 29282276 PMCID: PMC6004577 DOI: 10.1091/mbc.e17-06-0363] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 12/06/2017] [Accepted: 12/22/2017] [Indexed: 12/11/2022] Open
Abstract
The formin Delphilin binds the glutamate receptor, GluRδ2, in dendritic spines of Purkinje cells. Both proteins play a role in learning. To understand how Delphilin functions in neurons, we studied the actin assembly properties of this formin. Formins have a conserved formin homology 2 domain, which nucleates and associates with the fast-growing end of actin filaments, influencing filament growth together with the formin homology 1 (FH1) domain. The strength of nucleation and elongation varies widely across formins. Additionally, most formins have conserved domains that regulate actin assembly through an intramolecular interaction. Delphilin is distinct from other formins in several ways: its expression is limited to Purkinje cells, it lacks classical autoinhibitory domains, and its FH1 domain has minimal proline-rich sequence. We found that Delphilin is an actin nucleator that does not accelerate elongation, although it binds to the barbed end of filaments. In addition, Delphilin exhibits a preference for actin isoforms, nucleating nonmuscle actin but not muscle actin, which has not been described or systematically studied in other formins. Finally, Delphilin is the first formin studied that is not regulated by intramolecular interactions. We speculate how the activity we observe is consistent with its localization in the small dendritic spines.
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Affiliation(s)
- William T Silkworth
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Kristina L Kunes
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Grace C Nickel
- Department of Chemistry, Barnard College, New York, NY 10027
| | - Martin L Phillips
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Margot E Quinlan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095 .,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
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16
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Cytokinesis requires localized β-actin filament production by an actin isoform specific nucleator. Nat Commun 2017; 8:1530. [PMID: 29146911 PMCID: PMC5691081 DOI: 10.1038/s41467-017-01231-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 08/31/2017] [Indexed: 11/30/2022] Open
Abstract
Cytokinesis is initiated by the localized assembly of the contractile ring, a dynamic actomyosin structure that generates a membrane furrow between the segregating chromosomal masses to divide a cell into two. Here we show that the stabilization and organization of the cytokinetic furrow is specifically dependent on localized β-actin filament assembly at the site of cytokinesis. β-actin filaments are assembled directly at the furrow by an anillin-dependent pathway that enhances RhoA-dependent activation of the formin DIAPH3, an actin nucleator. DIAPH3 specifically generates homopolymeric filaments of β-actin in vitro. By employing enhancers and activators, cells can achieve acute spatio-temporal control over isoform-specific actin arrays that are required for distinct cellular functions. Cytokinesis is initiated by the localized assembly of the contractile ring. Here the authors show that the stabilization and organization of the cytokinetic furrow requires localized β-actin filament assembly at the site of cytokinesis by an actin isoform specific nucleator.
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17
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Vig AT, Földi I, Szikora S, Migh E, Gombos R, Tóth MÁ, Huber T, Pintér R, Talián GC, Mihály J, Bugyi B. The activities of the C-terminal regions of the formin protein disheveled-associated activator of morphogenesis (DAAM) in actin dynamics. J Biol Chem 2017. [PMID: 28642367 DOI: 10.1074/jbc.m117.799247] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Disheveled-associated activator of morphogenesis (DAAM) is a diaphanous-related formin protein essential for the regulation of actin cytoskeleton dynamics in diverse biological processes. The conserved formin homology 1 and 2 (FH1-FH2) domains of DAAM catalyze actin nucleation and processively mediate filament elongation. These activities are indirectly regulated by the N- and C-terminal regions flanking the FH1-FH2 domains. Recently, the C-terminal diaphanous-autoregulatory domain (DAD) and the C terminus (CT) of formins have also been shown to regulate actin assembly by directly interacting with actin. Here, to better understand the biological activities of DAAM, we studied the role of DAD-CT regions of Drosophila DAAM in its interaction with actin with in vitro biochemical and in vivo genetic approaches. We found that the DAD-CT region binds actin in vitro and that its main actin-binding element is the CT region, which does not influence actin dynamics on its own. However, we also found that it can tune the nucleating activity and the filament end-interaction properties of DAAM in an FH2 domain-dependent manner. We also demonstrate that DAD-CT makes the FH2 domain more efficient in antagonizing with capping protein. Consistently, in vivo data suggested that the CT region contributes to DAAM-mediated filopodia formation and dynamics in primary neurons. In conclusion, our results demonstrate that the CT region of DAAM plays an important role in actin assembly regulation in a biological context.
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Affiliation(s)
- Andrea Teréz Vig
- From the Department of Biophysics, Medical School, University of Pécs, Szigeti Str. 12, Pécs H-7624
| | - István Földi
- the Biological Research Centre, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, and
| | - Szilárd Szikora
- the Biological Research Centre, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, and
| | - Ede Migh
- the Biological Research Centre, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, and
| | - Rita Gombos
- the Biological Research Centre, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, and
| | - Mónika Ágnes Tóth
- From the Department of Biophysics, Medical School, University of Pécs, Szigeti Str. 12, Pécs H-7624
| | - Tamás Huber
- From the Department of Biophysics, Medical School, University of Pécs, Szigeti Str. 12, Pécs H-7624
| | - Réka Pintér
- From the Department of Biophysics, Medical School, University of Pécs, Szigeti Str. 12, Pécs H-7624
| | - Gábor Csaba Talián
- From the Department of Biophysics, Medical School, University of Pécs, Szigeti Str. 12, Pécs H-7624
| | - József Mihály
- the Biological Research Centre, Institute of Genetics, MTA-SZBK NAP B Axon Growth and Regeneration Group, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6726, and
| | - Beáta Bugyi
- From the Department of Biophysics, Medical School, University of Pécs, Szigeti Str. 12, Pécs H-7624, .,the Szentágothai Research Center, Ifjúság Str. 34, Pécs H-7624, Hungary
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18
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Marei H, Malliri A. GEFs: Dual regulation of Rac1 signaling. Small GTPases 2017; 8:90-99. [PMID: 27314616 PMCID: PMC5464116 DOI: 10.1080/21541248.2016.1202635] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/10/2016] [Accepted: 06/10/2016] [Indexed: 12/15/2022] Open
Abstract
GEFs play a critical role in regulating Rac1 signaling. They serve as signaling nodes converting upstream signals into downstream Rac1-driven cellular responses. Through associating with membrane-bound Rac1, GEFs facilitate the exchange of GDP for GTP, thereby activating Rac1. As a result, Rac1 undergoes conformational changes that mediate its interaction with downstream effectors, linking Rac1 to a multitude of physiological and pathological processes. Interestingly, there are at least 20 GEFs involved in Rac1 activation, suggesting a more complex role of GEFs in regulating Rac1 signaling apart from promoting the exchange of GDP for GTP. Indeed, accumulating evidence implicates GEFs in directing the specificity of Rac1-driven signaling cascades, although the underlying mechanisms were poorly defined. Recently, through conducting a comparative study, we highlighted the role of 2 Rac-specific GEFs, Tiam1 and P-Rex1, in dictating the biological outcome downstream of Rac1. Importantly, further proteomic analysis uncovered a GEF activity-independent function for both GEFs in modulating the Rac1 interactome, which results in the stimulation of GEF-specific signaling cascades. Here, we provide an overview of our recent findings and discuss the role of GEFs as master regulators of Rac1 signaling with a particular focus on GEF-mediated modulation of cell migration following Rac1 activation.
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Affiliation(s)
- Hadir Marei
- Cell Signaling Group, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, UK
| | - Angeliki Malliri
- Cell Signaling Group, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, UK
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19
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Shrivastava A, Prasad A, Kuzontkoski PM, Yu J, Groopman JE. Slit2N Inhibits Transmission of HIV-1 from Dendritic Cells to T-cells by Modulating Novel Cytoskeletal Elements. Sci Rep 2015; 5:16833. [PMID: 26582347 PMCID: PMC4652184 DOI: 10.1038/srep16833] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/20/2015] [Indexed: 11/30/2022] Open
Abstract
Dendritic cells are among the first cells to encounter sexually acquired human immunodeficiency virus (HIV-1), in the mucosa, and they can transmit HIV-1 to CD4(+) T-cells via an infectious synapse. Recent studies reveal that actin-rich membrane extensions establish direct contact between cells at this synapse and facilitate virus transmission. Genesis of these contacts involves signaling through c-Src and Cdc42, which modulate actin polymerization and filopodia formation via the Arp2/3 complex and Diaphanous 2 (Diaph2). We found that Slit2N, a ligand for the Roundabout (Robo) receptors, blocked HIV-1-induced signaling through Arp2/3 and Diaph2, decreased filopodial extensions on dendritic cells, and inhibited cell-to-cell transmission of HIV-1 in a Robo1-dependent manner. Employing proteomic analysis, we identified Flightless-1 as a novel, Robo1-interacting protein. Treatment with shRNAs reduced levels of Flightless-1 and demonstrated its role in efficient cell-to-cell transfer of HIV-1. These results suggest a novel strategy to limit viral infection in the host by targeting the Slit/Robo pathway with modulation of cytoskeletal elements previously unrecognized in HIV-1 transmission.
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Affiliation(s)
- Ashutosh Shrivastava
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Anil Prasad
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Paula M. Kuzontkoski
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
- DynaMed, EBSCO Information Services, 10 Estes Street, Ipswich, Massachusetts, USA
| | - Jinlong Yu
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
- Department of Psychiatry, Mclean Hospital, Harvard Medical School, 115 Mill Street, Belmont, Massachusetts, USA
| | - Jerome E. Groopman
- Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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20
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Arora PD, Wang Y, Bresnick A, Janmey PA, McCulloch CA. Flightless I interacts with NMMIIA to promote cell extension formation, which enables collagen remodeling. Mol Biol Cell 2015; 26:2279-97. [PMID: 25877872 PMCID: PMC4462945 DOI: 10.1091/mbc.e14-11-1536] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 04/09/2015] [Indexed: 01/14/2023] Open
Abstract
The role of the actin-capping protein flightless I in collagen remodeling by mouse fibroblasts is examined. Flightless and nonmuscle myosin IIA cooperate to enable collagen phagocytosis. We examined the role of the actin-capping protein flightless I (FliI) in collagen remodeling by mouse fibroblasts. FliI-overexpressing cells exhibited reduced spreading on collagen but formed elongated protrusions that stained for myosin10 and fascin and penetrated pores of collagen-coated membranes. Inhibition of Cdc42 blocked formation of cell protrusions. In FliI-knockdown cells, transfection with constitutively active Cdc42 did not enable protrusion formation. FliI-overexpressing cells displayed increased uptake and degradation of exogenous collagen and strongly compacted collagen fibrils, which was blocked by blebbistatin. Mass spectrometry analysis of FliI immunoprecipitates showed that FliI associated with nonmuscle myosin IIA (NMMIIA), which was confirmed by immunoprecipitation. GFP-FliI colocalized with NMMIIA at cell protrusions. Purified FliI containing gelsolin-like domains (GLDs) 1–6 capped actin filaments efficiently, whereas FliI GLD 2–6 did not. Binding assays showed strong interaction of purified FliI protein (GLD 1–6) with the rod domain of NMMIIA (kD = 0.146 μM), whereas FliI GLD 2–6 showed lower binding affinity (kD = 0.8584 μM). Cells expressing FliI GLD 2–6 exhibited fewer cell extensions, did not colocalize with NMMIIA, and showed reduced collagen uptake compared with cells expressing FliI GLD 1–6. We conclude that FliI interacts with NMMIIA to promote cell extension formation, which enables collagen remodeling in fibroblasts.
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Affiliation(s)
- Pamma D Arora
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Yongqiang Wang
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada
| | - Anne Bresnick
- Department of Biochemistry, Albert Einstein College of Medicine, New York, NY 10461
| | - Paul A Janmey
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Christopher A McCulloch
- Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON M5S 3E2, Canada
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21
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Abstract
Formin proteins were recognized as effectors of Rho GTPases some 15 years ago. They contribute to different cellular actin cytoskeleton structures by their ability to polymerize straight actin filaments at the barbed end. While not all formins necessarily interact with Rho GTPases, a subgroup of mammalian formins, termed Diaphanous-related formins or DRFs, were shown to be activated by small GTPases of the Rho superfamily. DRFs are autoinhibited in the resting state by an N- to C-terminal interaction that renders the central actin polymerization domain inactive. Upon the interaction with a GTP-bound Rho, Rac, or Cdc42 GTPase, the C-terminal autoregulation domain is displaced from its N-terminal recognition site and the formin becomes active to polymerize actin filaments. In this review we discuss the current knowledge on the structure, activation, and function of formin-GTPase interactions for the mammalian formin families Dia, Daam, FMNL, and FHOD. We describe both direct and indirect interactions of formins with GTPases, which lead to formin activation and cytoskeletal rearrangements. The multifaceted function of formins as effector proteins of Rho GTPases thus reflects the diversity of the actin cytoskeleton in cells.
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Affiliation(s)
- Sonja Kühn
- Center of Advanced European Studies and Research (caesar); Group Physical Biochemistry; Bonn, Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research (caesar); Group Physical Biochemistry; Bonn, Germany
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22
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Jochim N, Gerhard R, Just I, Pich A. Time-resolved cellular effects induced by TcdA from Clostridium difficile. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:1089-1100. [PMID: 24711272 DOI: 10.1002/rcm.6882] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/07/2014] [Accepted: 02/26/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE The anaerobe Clostridium difficile is a common pathogen that causes infection of the colon leading to diarrhea or pseudomembranous colitis. Its major virulence factors are toxin A (TcdA) and toxin B (TcdB), which specifically inactivate small GTPases by glucosylation leading to reorganization of the cytoskeleton and finally to cell death. In the present work a quantitative proteome analysis using the isotope-coded protein label (ICPL) approach was conducted to investigate proteome changes in the colon cell line Caco-2 after treatment with recombinant wild-type TcdA (rTcdA-wt) or a glucosyltransferase-deficient mutant TcdA (rTcdA-mut). METHODS Proteins from crude cell lysates or cellular subfractions were identified by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). Two time points (5 h, 24 h) of toxin treatment were analyzed and about 4000 proteins were identified in each case. RESULTS After 5 h treatment with rTcdA-wt, 150 proteins had a significantly altered abundance; rTcdA-mut caused regulation of 50 proteins at this time point. After 24 h treatment with rTcdA-wt changes in abundance of 61 proteins were observed, but no changes in protein abundance were detected after 24 h if cells were treated with rTcdA-mut. TcdA affected several proteins involved in signaling events, cytoskeleton and cell-cell contact organization, translation, and metabolic processes. The ICPL-dependent quantification was verified by label-free targeted MS techniques based on multiple reaction monitoring (MRM) and triple quadrupole mass spectrometry. CONCLUSIONS LC/MS-based proteome analyses and the ICPL approach revealed comprehensive and reproducible proteome date and provided new insights into the cellular effects of clostridial glucosylating toxins (CGT).
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Affiliation(s)
- Nelli Jochim
- Hannover Medical School, Institute of Toxicology, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
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23
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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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24
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Smith TC, Fridy PC, Li Y, Basil S, Arjun S, Friesen RM, Leszyk J, Chait BT, Rout MP, Luna EJ. Supervillin binding to myosin II and synergism with anillin are required for cytokinesis. Mol Biol Cell 2013; 24:3603-19. [PMID: 24088567 PMCID: PMC3842989 DOI: 10.1091/mbc.e12-10-0714] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cytokinesis, the process by which cytoplasm is apportioned between dividing daughter cells, requires coordination of myosin II function, membrane trafficking, and central spindle organization. Most known regulators act during late cytokinesis; a few, including the myosin II-binding proteins anillin and supervillin, act earlier. Anillin's role in scaffolding the membrane cortex with the central spindle is well established, but the mechanism of supervillin action is relatively uncharacterized. We show here that two regions within supervillin affect cell division: residues 831-1281, which bind central spindle proteins, and residues 1-170, which bind the myosin II heavy chain (MHC) and the long form of myosin light-chain kinase. MHC binding is required to rescue supervillin deficiency, and mutagenesis of this site creates a dominant-negative phenotype. Supervillin concentrates activated and total myosin II at the furrow, and simultaneous knockdown of supervillin and anillin additively increases cell division failure. Knockdown of either protein causes mislocalization of the other, and endogenous anillin increases upon supervillin knockdown. Proteomic identification of interaction partners recovered using a high-affinity green fluorescent protein nanobody suggests that supervillin and anillin regulate the myosin II and actin cortical cytoskeletons through separate pathways. We conclude that supervillin and anillin play complementary roles during vertebrate cytokinesis.
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Affiliation(s)
- Tara C Smith
- Program in Cell and Developmental Dynamics, Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655 Laboratory of Cellular and Structural Biology, Rockefeller University, New York, NY 10065 Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, NY 10065 Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Shrewsbury, MA 01545
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25
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Ditlev JA, Mayer BJ, Loew LM. There is more than one way to model an elephant. Experiment-driven modeling of the actin cytoskeleton. Biophys J 2013; 104:520-32. [PMID: 23442903 DOI: 10.1016/j.bpj.2012.12.044] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 10/27/2022] Open
Abstract
Mathematical modeling has established its value for investigating the interplay of biochemical and mechanical mechanisms underlying actin-based motility. Because of the complex nature of actin dynamics and its regulation, many of these models are phenomenological or conceptual, providing a general understanding of the physics at play. But the wealth of carefully measured kinetic data on the interactions of many of the players in actin biochemistry cries out for the creation of more detailed and accurate models that could permit investigators to dissect interdependent roles of individual molecular components. Moreover, no human mind can assimilate all of the mechanisms underlying complex protein networks; so an additional benefit of a detailed kinetic model is that the numerous binding proteins, signaling mechanisms, and biochemical reactions can be computationally organized in a fully explicit, accessible, visualizable, and reusable structure. In this review, we will focus on how comprehensive and adaptable modeling allows investigators to explain experimental observations and develop testable hypotheses on the intracellular dynamics of the actin cytoskeleton.
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Affiliation(s)
- Jonathon A Ditlev
- Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut, USA
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26
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Jaiswal R, Stepanik V, Rankova A, Molinar O, Goode BL, McCartney BM. Drosophila homologues of adenomatous polyposis coli (APC) and the formin diaphanous collaborate by a conserved mechanism to stimulate actin filament assembly. J Biol Chem 2013; 288:13897-905. [PMID: 23558679 DOI: 10.1074/jbc.m113.462051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Vertebrate APC collaborates with Dia through its Basic domain to assemble actin filaments. RESULTS Despite limited sequence homology between the vertebrate and Drosophila APC Basic domains, Drosophila APC1 collaborates with Dia to stimulate actin assembly in vitro. CONCLUSION The mechanism of actin assembly is highly conserved over evolution. SIGNIFICANCE APC-Dia collaborations may be crucial in a wide range of animal cells. Adenomatous polyposis coli (APC) is a large multidomain protein that regulates the cytoskeleton. Recently, it was shown that vertebrate APC through its Basic domain directly collaborates with the formin mDia1 to stimulate actin filament assembly in the presence of nucleation barriers. However, it has been unclear whether these activities extend to homologues of APC and Dia in other organisms. Drosophila APC and Dia are each required to promote actin furrow formation in the syncytial embryo, suggesting a potential collaboration in actin assembly, but low sequence homology between the Basic domains of Drosophila and vertebrate APC has left their functional and mechanistic parallels uncertain. To address this question, we purified Drosophila APC1 and Dia and determined their individual and combined effects on actin assembly using both bulk fluorescence assays and total internal reflection fluorescence microscopy. Our data show that APC1, similar to its vertebrate homologue, bound to actin monomers and nucleated and bundled filaments. Further, Drosophila Dia nucleated actin assembly and protected growing filament barbed ends from capping protein. Drosophila APC1 and Dia directly interacted and collaborated to promote actin assembly in the combined presence of profilin and capping protein. Thus, despite limited sequence homology, Drosophila and vertebrate APCs exhibit highly related activities and mechanisms and directly collaborate with formins. These results suggest that APC-Dia interactions in actin assembly are conserved and may underlie important in vivo functions in a broad range of animal phyla.
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Affiliation(s)
- Richa Jaiswal
- Department of Biology, Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA
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Strudwick XL, Cowin AJ. Cytoskeletal regulation of dermal regeneration. Cells 2012; 1:1313-27. [PMID: 24710556 PMCID: PMC3901152 DOI: 10.3390/cells1041313] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 11/15/2012] [Accepted: 12/04/2012] [Indexed: 12/21/2022] Open
Abstract
Wound healing results in the repair of injured tissues however fibrosis and scar formation are, more often than not the unfortunate consequence of this process. The ability of lower order vertebrates and invertebrates to regenerate limbs and tissues has been all but lost in mammals; however, there are some instances where glimpses of mammalian regenerative capacity do exist. Here we describe the unlocked potential that exists in mammals that may help us understand the process of regeneration post-injury and highlight the potential role of the actin cytoskeleton in this process. The precise function and regulation of the cytoskeleton is critical to the success of the healing process and its manipulation may therefore facilitate regenerative healing. The gelsolin family of actin remodelling proteins in particular has been shown to have important functions in wound healing and family member Flightless I (Flii) is involved in both regeneration and repair. Understanding the interactions between different cytoskeletal proteins and their dynamic control of processes including cellular adhesion, contraction and motility may assist the development of therapeutics that will stimulate regeneration rather than repair.
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Affiliation(s)
- Xanthe L Strudwick
- Wound Healing Laboratory, Women's and Children's Health Research Institute, 72 King William Road, North Adelaide, South Australia 5006, Australia.
| | - Allison J Cowin
- Wound Healing Laboratory, Women's and Children's Health Research Institute, 72 King William Road, North Adelaide, South Australia 5006, Australia.
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Han Y, Yu G, Sarioglu H, Caballero-Martinez A, Schlott F, Ueffing M, Haase H, Peschel C, Krackhardt AM. Proteomic investigation of the interactome of FMNL1 in hematopoietic cells unveils a role in calcium-dependent membrane plasticity. J Proteomics 2012. [PMID: 23182705 DOI: 10.1016/j.jprot.2012.11.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Formin-like 1 (FMNL1) is a formin-related protein highly expressed in hematopoietic cells and overexpressed in leukemias as well as diverse transformed cell lines. It has been described to play a role in diverse functions of hematopoietic cells such as phagocytosis of macrophages as well as polarization and cytotoxicity of T cells. However, the specific role of FMNL1 in these processes has not been clarified yet and regulation by interaction partners in primary hematopoietic cells has never been investigated. We performed a proteomic screen for investigation of the interactome of FMNL1 in primary hematopoietic cells resulting in the identification of a number of interaction partners. Bioinformatic analysis considering semantic similarity suggested the giant protein AHNAK1 to be an essential interaction partner of FMNL1. We confirmed AHNAK1 as a general binding partner for FMNL1 in diverse hematopoietic cells and demonstrate that the N-terminal part of FMNL1 binds to the C-terminus of AHNAK1. Moreover, we show that the constitutively activated form of FMNL1 (FMNL1γ) induces localization of AHNAK1 to the cell membrane. Finally, we provide evidence that overexpression or knock down of FMNL1 has an impact on the capacitative calcium influx after ionomycin-mediated activation of diverse cell lines and primary cells.
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Affiliation(s)
- Yanan Han
- Medizinische Klinik III, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany
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29
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Mohammad I, Arora PD, Naghibzadeh Y, Wang Y, Li J, Mascarenhas W, Janmey PA, Dawson JF, McCulloch CA. Flightless I is a focal adhesion-associated actin-capping protein that regulates cell migration. FASEB J 2012; 26:3260-72. [PMID: 22581781 DOI: 10.1096/fj.11-202051] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The role of adhesion-associated actin-binding proteins in cell migration is not well defined. In mouse fibroblasts we screened for focal adhesion-associated proteins that were isolated with collagen-coated beads and detected by tandem mass spectrometry. We identified flightless I (FliI) as an actin-binding protein in focal adhesion fractions, which was verified by immunoblotting. By confocal microscopy most FliI was distributed throughout the cytosol and in focal adhesions. By sedimentation assays and in vitro binding assays, we found that FliI associates with actin filaments and actin monomers. Assays using purified proteins showed that FliI inhibits actin polymerization and caps but does not sever actin filaments. Cells with FliI knockdown or cells overexpressing FliI migrated more or less rapidly, respectively, than wild-type controls. Compared with controls, cells with FliI knockdown were less adherent than wild-type cells, exhibited reduced numbers of focal adhesions containing activated β1 integrins and vinculin, and exhibited increased incorporation of actin monomers into nascent filaments at focal adhesions. These data indicate that FliI regulates cell migration through its localization to focal adhesions and its ability to cap actin filaments, which collectively affect focal adhesion maturation.
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Affiliation(s)
- Ibrahim Mohammad
- Matrix Dynamics Group, University of Toronto, Toronto, Ontario, Canada
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30
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Okada H, Uezu A, Mason FM, Soderblom EJ, Moseley MA, Soderling SH. SH3 domain-based phototrapping in living cells reveals Rho family GAP signaling complexes. Sci Signal 2011; 4:rs13. [PMID: 22126966 DOI: 10.1126/scisignal.2002189] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rho family GAPs [guanosine triphosphatase (GTPase) activating proteins] negatively regulate Rho family GTPase activity and therefore modulate signaling events that control cytoskeletal dynamics. The spatial distribution of these GAPs and their specificity toward individual GTPases are controlled by their interactions with various proteins within signaling complexes. These interactions are likely mediated through the Src homology 3 (SH3) domain, which is abundant in the Rho family GAP proteome and exhibits a micromolar binding affinity, enabling the Rho family GAPs to participate in transient interactions with multiple binding partners. To capture these elusive GAP signaling complexes in situ, we developed a domain-based proteomics approach, starting with in vivo phototrapping of SH3 domain-binding proteins and the mass spectrometry identification of associated proteins for nine representative Rho family GAPs. After the selection of candidate binding proteins by cluster analysis, we performed peptide array-based high-throughput in vitro binding assays to confirm the direct interactions and map the SH3 domain-binding sequences. We thereby identified 54 SH3-mediated binding interactions (including 51 previously unidentified ones) for nine Rho family GAPs. We constructed Rho family GAP interactomes that provided insight into the functions of these GAPs. We further characterized one of the predicted functions for the Rac-specific GAP WRP and identified a role for WRP in mediating clustering of the postsynaptic scaffolding protein gephyrin and the GABA(A) (γ-aminobutyric acid type A) receptor at inhibitory synapses.
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Affiliation(s)
- Hirokazu Okada
- Department of Cell Biology, Duke University Medical School, Durham, NC 27710, USA
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31
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Graziano BR, DuPage AG, Michelot A, Breitsprecher D, Moseley JB, Sagot I, Blanchoin L, Goode BL. Mechanism and cellular function of Bud6 as an actin nucleation-promoting factor. Mol Biol Cell 2011; 22:4016-28. [PMID: 21880892 PMCID: PMC3204064 DOI: 10.1091/mbc.e11-05-0404] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Bud6 functions as an actin nucleation–promoting factor (NPF) for Bni1; thus formins can depend on NPFs like the Arp2/3 complex. Unexpected parallels exist between Bud6 and WASp. Bud6 is the first nonmetazoan example of formins pairing with actin monomer–binding proteins to stimulate nucleation, akin to Spire-Capu and APC-mDia1 Formins are a conserved family of actin assembly–promoting factors with diverse biological roles, but how their activities are regulated in vivo is not well understood. In Saccharomyces cerevisiae, the formins Bni1 and Bnr1 are required for the assembly of actin cables and polarized cell growth. Proper cable assembly further requires Bud6. Previously it was shown that Bud6 enhances Bni1-mediated actin assembly in vitro, but the biochemical mechanism and in vivo role of this activity were left unclear. Here we demonstrate that Bud6 specifically stimulates the nucleation rather than the elongation phase of Bni1-mediated actin assembly, defining Bud6 as a nucleation-promoting factor (NPF) and distinguishing its effects from those of profilin. We generated alleles of Bud6 that uncouple its interactions with Bni1 and G-actin and found that both interactions are critical for NPF activity. Our data indicate that Bud6 promotes filament nucleation by recruiting actin monomers to Bni1. Genetic analysis of the same alleles showed that Bud6 regulation of formin activity is critical for normal levels of actin cable assembly in vivo. Our results raise important mechanistic parallels between Bud6 and WASP, as well as between Bud6 and other NPFs that interact with formins such as Spire.
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Affiliation(s)
- Brian R Graziano
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
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Lecuit T, Lenne PF, Munro E. Force generation, transmission, and integration during cell and tissue morphogenesis. Annu Rev Cell Dev Biol 2011; 27:157-84. [PMID: 21740231 DOI: 10.1146/annurev-cellbio-100109-104027] [Citation(s) in RCA: 386] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cell shape changes underlie a large set of biological processes ranging from cell division to cell motility. Stereotyped patterns of cell shape changes also determine tissue remodeling events such as extension or invagination. In vitro and cell culture systems have been essential to understanding the fundamental physical principles of subcellular mechanics. These are now complemented by studies in developing organisms that emphasize how cell and tissue morphogenesis emerge from the interplay between force-generating machines, such as actomyosin networks, and adhesive clusters that transmit tensile forces at the cell cortex and stabilize cell-cell and cell-substrate interfaces. Both force production and transmission are self-organizing phenomena whose adaptive features are essential during tissue morphogenesis. A new era is opening that emphasizes the similarities of and allows comparisons between distant dynamic biological phenomena because they rely on core machineries that control universal features of cytomechanics.
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Affiliation(s)
- Thomas Lecuit
- Developmental Biology Institute of Marseilles-Luminy, Centre National de la Recherche Scientifique, Université de la Méditerranée, 13288 Marseille Cedex 9, France.
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Kopecki Z, O'Neill GM, Arkell RM, Cowin AJ. Regulation of focal adhesions by flightless i involves inhibition of paxillin phosphorylation via a Rac1-dependent pathway. J Invest Dermatol 2011; 131:1450-9. [PMID: 21430700 DOI: 10.1038/jid.2011.69] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Flightless I (Flii) is an actin-remodeling protein that influences diverse processes including cell migration and gene transcription and links signal transduction with cytoskeletal regulation. Here, we show that Flii modulation of focal adhesions and filamentous actin stress fibers is Rac1-dependent. Using primary skin fibroblasts from Flii overexpressing (Flii(Tg/Tg)), wild-type, and Flii deficient (Flii(+/-)) mice, we show that elevated expression of Flii increases stress fiber formation by impaired focal adhesion turnover and enhanced formation of fibrillar adhesions. Conversely, Flii knockdown increases the percentage of focal complex positive cells. We further show that a functional effect of Flii at both the cellular level and in in vivo mouse wounds is through inhibiting paxillin tyrosine phosphorylation and suppression of signaling proteins Src and p130Cas, both of which regulate adhesion signaling pathways. Flii is upregulated in response to wounding, and overexpression of Flii inhibits paxillin activity and reduces adhesion signaling by modulating the activity of the Rho family GTPases. Overexpression of constitutively active Rac1 GTPase restores the spreading ability of Flii(Tg/Tg) fibroblasts and may explain the reduced adhesion, migration, and proliferation observed in Flii(Tg/Tg) mice and their impaired wound healing, a process dependent on effective cellular motility and adhesion.
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Affiliation(s)
- Zlatko Kopecki
- Wound Healing Laboratory, Women's and Children's Health Research Institute, University of Adelaide, North Adelaide, South Australia, Australia
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Li GH, Arora PD, Chen Y, McCulloch CA, Liu P. Multifunctional roles of gelsolin in health and diseases. Med Res Rev 2010; 32:999-1025. [PMID: 22886630 DOI: 10.1002/med.20231] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Gelsolin, a Ca(2+) -regulated actin filament severing, capping, and nucleating protein, is an ubiquitous, multifunctional regulator of cell structure and metabolism. More recent data show that gelsolin can act as a transcriptional cofactor in signal transduction and its own expression and function can be influenced by epigenetic changes. Here, we review the functions of the plasma and cytoplasmic forms of gelsolin, and their manifold impacts on cancer, apoptosis, infection and inflammation, cardiac injury, pulmonary diseases, and aging. An improved understanding of the functions and regulatory mechanisms of gelsolin may lead to new considerations of this protein as a potential biomarker and/or therapeutic target.
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Affiliation(s)
- Guo Hua Li
- Toronto General Hospital, University Health Network, Toronto, Ontario, Canada
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