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Liu T, Cao L, Mladenov M, Jegou A, Way M, Moores CA. Cortactin stabilizes actin branches by bridging activated Arp2/3 to its nucleated actin filament. Nat Struct Mol Biol 2024; 31:801-809. [PMID: 38267598 PMCID: PMC11102864 DOI: 10.1038/s41594-023-01205-2] [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: 07/25/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024]
Abstract
Regulation of the assembly and turnover of branched actin filament networks nucleated by the Arp2/3 complex is essential during many cellular processes, including cell migration and membrane trafficking. Cortactin is important for actin branch stabilization, but the mechanism by which this occurs is unclear. Given this, we determined the structure of vertebrate cortactin-stabilized Arp2/3 actin branches using cryogenic electron microscopy. We find that cortactin interacts with the new daughter filament nucleated by the Arp2/3 complex at the branch site, rather than the initial mother actin filament. Cortactin preferentially binds activated Arp3. It also stabilizes the F-actin-like interface of activated Arp3 with the first actin subunit of the new filament, and its central repeats extend along successive daughter-filament subunits. The preference of cortactin for activated Arp3 explains its retention at the actin branch and accounts for its synergy with other nucleation-promoting factors in regulating branched actin network dynamics.
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Affiliation(s)
- Tianyang Liu
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK
| | - Luyan Cao
- The Francis Crick Institute, London, UK
| | | | - Antoine Jegou
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Michael Way
- The Francis Crick Institute, London, UK.
- Department of Infectious Disease, Imperial College, London, UK.
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK.
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2
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Guo E, Chou SZ, Lara-Tejero M, Galan JE. Cryo-EM structure of the bacterial effector protein SipA bound to F-actin reveals a unique mechanism for filament stabilization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.21.572903. [PMID: 38187563 PMCID: PMC10769390 DOI: 10.1101/2023.12.21.572903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The bacterial pathogen Salmonella spp. modulates cellular processes by delivering effector proteins through its type III secretion systems. Among these effectors, SipA facilitates bacterial invasion and promotes intestinal inflammation. The mechanisms by which this effector carries out these functions are incompletely understood although SipA's ability to modulate actin dynamics is central to some of these activities. Here we report the cryo-EM structure of SipA bound to filamentous actin. We show that this effector stabilizes actin filaments through unique interactions of its carboxy terminal domain with four actin subunits. Furthermore, our structure-function studies revealed that SipA's actin-binding activity is independent from its ability to stimulate intestinal inflammation. Overall, these studies illuminate critical aspects of Salmonella pathogenesis, and provide unique insight into the mechanisms by which a bacterial effector modulates actin dynamics.
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3
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McGuirk ER, Koundinya N, Nagarajan P, Padrick SB, Goode BL. Direct observation of cortactin protecting Arp2/3-actin filament branch junctions from GMF-mediated destabilization. Eur J Cell Biol 2024; 103:151378. [PMID: 38071835 PMCID: PMC10843626 DOI: 10.1016/j.ejcb.2023.151378] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/02/2023] [Accepted: 12/02/2023] [Indexed: 01/28/2024] Open
Abstract
How cells tightly control the formation and turnover of branched actin filament arrays to drive cell motility, endocytosis, and other cellular processes is still not well understood. Here, we investigated the mechanistic relationship between two binding partners of the Arp2/3 complex, glia maturation factor (GMF) and cortactin. Individually, GMF and cortactin have opposite effects on the stability of actin filament branches, but it is unknown how they work in concert with each other to govern branch turnover. Using TIRF microscopy, we observe that GMF's branch destabilizing activities are potently blocked by cortactin (IC50 = 1.3 nM) and that this inhibition requires direct interactions of cortactin with Arp2/3 complex. The simplest model that would explain these results is competition for binding Arp2/3 complex. However, we find that cortactin and GMF do not compete for free Arp2/3 complex in solution. Further, we use single molecule analysis to show that cortactin's on-rate (3 ×107 s-1 M-1) and off-rate (0.03 s-1) at branch junctions are minimally affected by excess GMF. Together, these results show that cortactin binds with high affinity to branch junctions, where it blocks the destabilizing effects of GMF, possibly by a mechanism that is allosteric in nature. In addition, the affinities we measure for cortactin at actin filament branch junctions (Kd = 0.9 nM) and filament sides (Kd = 206 nM) are approximately 20-fold stronger than previously reported. These observations contribute to an emerging view of molecular complexity in how Arp2/3 complex is regulated through the integration of multiple inputs.
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Affiliation(s)
- Emma R McGuirk
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Neha Koundinya
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Priyashree Nagarajan
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Shae B Padrick
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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4
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Delaunay M, Paterek A, Gautschi I, Scherler G, Diviani D. AKAP2-anchored extracellular signal-regulated kinase 1 (ERK1) regulates cardiac myofibroblast migration. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119674. [PMID: 38242328 DOI: 10.1016/j.bbamcr.2024.119674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/22/2023] [Accepted: 01/10/2024] [Indexed: 01/21/2024]
Abstract
Cardiac fibrosis is a major cause of dysfunctions and arrhythmias in failing hearts. At the cellular level fibrosis is mediated by cardiac myofibroblasts, which display an increased migratory capacity and secrete large amounts of extracellular matrix. These properties allow myofibroblasts to invade, remodel and stiffen the myocardium and eventually alter cardiac function. While the enhanced ability of cardiac myofibroblasts to migrate has been proposed to contribute to the initiation of the fibrotic process, the molecular mechanisms controlling their motile function have been poorly defined. In this context, our current findings indicate that A-kinase anchoring protein 2 (AKAP2) associates with actin at the leading edge of migrating cardiac myofibroblasts. Proteomic analysis of the AKAP2 interactome revealed that this anchoring protein assembles a signaling complex composed of the extracellular regulated kinase 1 (ERK1) and its upstream activator Grb2 that mediates the activation of ERK in cardiac myofibroblasts. Silencing AKAP2 expression results in a significant reduction in the phosphorylation of ERK1 and its downstream effector WAVE2, a protein involved in actin polymerization, and impairs the ability of cardiac myofibroblasts to migrate. Importantly, disruption of the interaction between AKAP2 and F-actin using cell-permeant competitor peptides, inhibits the activation of the ERK-WAVE2 signaling axis, resulting in a reduction of the translocation of Arp2 to the leading-edge membrane and in inhibition of cardiac myofibroblast migration. Collectively, these findings suggest that AKAP2 functions as an F-actin bound molecular scaffold mediating the activation of an ERK1-dependent promigratory transduction pathway in cardiac myofibroblasts.
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Affiliation(s)
- Marion Delaunay
- Department of Biomedical Sciences, Faculty of Biology et Medicine, University of Lausanne, 1011 Lausanne, Switzerland
| | - Aleksandra Paterek
- Department of Biomedical Sciences, Faculty of Biology et Medicine, University of Lausanne, 1011 Lausanne, Switzerland
| | - Ivan Gautschi
- Department of Biomedical Sciences, Faculty of Biology et Medicine, University of Lausanne, 1011 Lausanne, Switzerland
| | - Greta Scherler
- Department of Biomedical Sciences, Faculty of Biology et Medicine, University of Lausanne, 1011 Lausanne, Switzerland
| | - Dario Diviani
- Department of Biomedical Sciences, Faculty of Biology et Medicine, University of Lausanne, 1011 Lausanne, Switzerland.
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5
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Kuiper JWP, Gregg HL, Schüber M, Klein J, Hauck CR. Controling the cytoskeleton during CEACAM3-mediated phagocytosis. Eur J Cell Biol 2024; 103:151384. [PMID: 38215579 DOI: 10.1016/j.ejcb.2024.151384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/20/2023] [Accepted: 01/03/2024] [Indexed: 01/14/2024] Open
Abstract
Phagocytosis, an innate defense mechanism of multicellular animals, is initiated by specialized surface receptors. A phagocytic receptor expressed by human polymorphonuclear granulocytes, the major professional phagocytes in our body, is one of the fastest evolving human proteins implying a special role in human biology. This receptor, CEACAM3, is a member of the CarcinoEmbryonic Antigen-related Cell Adhesion Molecule (CEACAM) family and dedicated to the immediate recognition and rapid internalization of human-restricted pathogens. In this focused contribution, we will review the special adaptations of this protein, which co-evolves with different species of mucosa-colonizing bacteria. While the extracellular Immunoglobulin-variable (IgV)-like domain recognizes various bacterial adhesins, an Immunoreceptor Tyrosine-based Activation Motif (ITAM)-like sequence in the cytoplasmic tail of CEACAM3 constitutes the central signaling hub to trigger actin rearrangements needed for efficient phagocytosis. A major emphasis of this review will be placed on recent findings, which have revealed the multi-level control of this powerful phagocytic device. As tyrosine phosphorylation and small GTPase activity are central for CEACAM3-mediated phagocytosis, the counterregulation of CEACAM3 activity involves the receptor-type protein tyrosine phosphatase J (PTPRJ) as well as the Rac-GTP scavenging protein Cyri-B. Interference with such negative regulatory circuits has revealed that CEACAM3-mediated phagocytosis can be strongly enhanced. In principle, the knowledge gained by studying CEACAM3 can be applied to other phagocytic systems and opens the door to treatments, which boost the phagocytic capacity of professional phagocytes.
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Affiliation(s)
| | - Helena L Gregg
- Lehrstuhl Zellbiologie, Fachbereich Biologie, Universität Konstanz, Germany
| | - Meike Schüber
- Lehrstuhl Zellbiologie, Fachbereich Biologie, Universität Konstanz, Germany
| | - Jule Klein
- Lehrstuhl Zellbiologie, Fachbereich Biologie, Universität Konstanz, Germany
| | - Christof R Hauck
- Lehrstuhl Zellbiologie, Fachbereich Biologie, Universität Konstanz, Germany; Konstanz Research School Chemical Biology, Universität Konstanz, Germany.
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6
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Fokin AI, Boutillon A, James J, Courtois L, Vacher S, Simanov G, Wang Y, Polesskaya A, Bièche I, David NB, Gautreau AM. Inactivating negative regulators of cortical branched actin enhances persistence of single cell migration. J Cell Sci 2024; 137:jcs261332. [PMID: 38059420 DOI: 10.1242/jcs.261332] [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: 05/13/2023] [Accepted: 11/30/2023] [Indexed: 12/08/2023] Open
Abstract
The Rac1-WAVE-Arp2/3 pathway pushes the plasma membrane by polymerizing branched actin, thereby powering membrane protrusions that mediate cell migration. Here, using knockdown (KD) or knockout (KO), we combine the inactivation of the Arp2/3 inhibitory protein arpin, the Arp2/3 subunit ARPC1A and the WAVE complex subunit CYFIP2, all of which enhance the polymerization of cortical branched actin. Inactivation of the three negative regulators of cortical branched actin increases migration persistence of human breast MCF10A cells and of endodermal cells in the zebrafish embryo, significantly more than any single or double inactivation. In the triple KO cells, but not in triple KD cells, the 'super-migrator' phenotype was associated with a heterogenous downregulation of vimentin (VIM) expression and a lack of coordination in collective behaviors, such as wound healing and acinus morphogenesis. Re-expression of vimentin in triple KO cells largely restored normal persistence of single cell migration, suggesting that vimentin downregulation contributes to the maintenance of the super-migrator phenotype in triple KO cells. Constant excessive production of branched actin at the cell cortex thus commits cells into a motile state through changes in gene expression.
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Affiliation(s)
- Artem I Fokin
- CNRS UMR7654, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Arthur Boutillon
- INSERM U1182, CNRS UMR7645, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - John James
- CNRS UMR7654, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Laura Courtois
- Pharmacogenomics Unit, Department of Genetics, Institut Curie, 26 rue d'Ulm, 75005 Paris, France
| | - Sophie Vacher
- Pharmacogenomics Unit, Department of Genetics, Institut Curie, 26 rue d'Ulm, 75005 Paris, France
| | - Gleb Simanov
- CNRS UMR7654, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Yanan Wang
- CNRS UMR7654, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Anna Polesskaya
- CNRS UMR7654, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Ivan Bièche
- Pharmacogenomics Unit, Department of Genetics, Institut Curie, 26 rue d'Ulm, 75005 Paris, France
| | - Nicolas B David
- INSERM U1182, CNRS UMR7645, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
| | - Alexis M Gautreau
- CNRS UMR7654, Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France
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7
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Nanda S, Calderon A, Sachan A, Duong TT, Koch J, Xin X, Solouk-Stahlberg D, Wu YW, Nalbant P, Dehmelt L. Rho GTPase activity crosstalk mediated by Arhgef11 and Arhgef12 coordinates cell protrusion-retraction cycles. Nat Commun 2023; 14:8356. [PMID: 38102112 PMCID: PMC10724141 DOI: 10.1038/s41467-023-43875-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 11/22/2023] [Indexed: 12/17/2023] Open
Abstract
Rho GTPases play a key role in the spatio-temporal coordination of cytoskeletal dynamics during cell migration. Here, we directly investigate crosstalk between the major Rho GTPases Rho, Rac and Cdc42 by combining rapid activity perturbation with activity measurements in mammalian cells. These studies reveal that Rac stimulates Rho activity. Direct measurement of spatio-temporal activity patterns show that Rac activity is tightly and precisely coupled to local cell protrusions, followed by Rho activation during retraction. Furthermore, we find that the Rho-activating Lbc-type GEFs Arhgef11 and Arhgef12 are enriched at transient cell protrusions and retractions and recruited to the plasma membrane by active Rac. In addition, their depletion reduces activity crosstalk, cell protrusion-retraction dynamics and migration distance and increases migration directionality. Thus, our study shows that Arhgef11 and Arhgef12 facilitate exploratory cell migration by coordinating cell protrusion and retraction by coupling the activity of the associated regulators Rac and Rho.
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Affiliation(s)
- Suchet Nanda
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Abram Calderon
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Arya Sachan
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
| | - Thanh-Thuy Duong
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Johannes Koch
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, 45141, Essen, Germany
| | - Xiaoyi Xin
- SciLifeLab and Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, 90187, Umeå, Sweden
| | - Djamschid Solouk-Stahlberg
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Yao-Wen Wu
- SciLifeLab and Department of Chemistry, Umeå Centre for Microbial Research, Umeå University, 90187, Umeå, Sweden
| | - Perihan Nalbant
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, 45141, Essen, Germany.
| | - Leif Dehmelt
- Fakultät für Chemie und Chemische Biologie, TU Dortmund University, 44227, Dortmund, Germany.
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8
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Mandal S, Melo M, Gordiichuk P, Acharya S, Poh YC, Li N, Aung A, Dane EL, Irvine DJ, Kumari S. WASP facilitates tumor mechanosensitivity in T lymphocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.02.560434. [PMID: 37873483 PMCID: PMC10592916 DOI: 10.1101/2023.10.02.560434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Cytotoxic T lymphocytes (CTLs) carry out immunosurveillance by scanning target cells of diverse physical properties for the presence of antigens. While the recognition of cognate antigen by the T cell receptor is the primary signal for CTL activation, it has become increasingly clear that the mechanical stiffness of target cells plays an important role in antigen-triggered T cell responses. However, the molecular machinery within CTLs that transduces the mechanical information of tumor cells remains unclear. We find that CTL's mechanosensitive ability requires the activity of the actin-organizing protein Wiskott-Aldrich Syndrome Protein (WASP). WASP activation is modulated by the mechanical properties of antigen-presenting contexts across a wide range of target cell stiffnesses and activated WASP then mediates mechanosensitive activation of early TCR signaling markers in the CTL. Our results provide a molecular link between antigen mechanosensing and CTL immune response and suggest that CTL-intrinsic cytoskeletal organizing principles enable the processing of mechanical information from diverse target cells.
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Affiliation(s)
| | - Mariane Melo
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
| | | | | | - Yeh-Chuin Poh
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
| | - Na Li
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
| | - Aereas Aung
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
| | - Eric L. Dane
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
| | - Darrell J. Irvine
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
- Department of Biological Engineering, MIT, Cambridge, USA
- Howard Hughes Medical Institute, Ashburn, Virginia, USA
| | - Sudha Kumari
- Indian Institute of Science, Bengaluru, India
- Koch Institute of Integrative Cancer Research, MIT, Cambridge, USA
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9
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Singh Y, Hocky GM, Nolen BJ. Molecular dynamics simulations support a multistep pathway for activation of branched actin filament nucleation by Arp2/3 complex. J Biol Chem 2023; 299:105169. [PMID: 37595874 PMCID: PMC10514467 DOI: 10.1016/j.jbc.2023.105169] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 08/20/2023] Open
Abstract
Actin-related protein 2/3 complex (Arp2/3 complex) catalyzes the nucleation of branched actin filaments that push against membranes in processes like cellular motility and endocytosis. During activation by WASP proteins, the complex must bind WASP and engage the side of a pre-existing (mother) filament before a branched filament is nucleated. Recent high-resolution structures of activated Arp2/3 complex revealed two major sets of activating conformational changes. How these activating conformational changes are triggered by interactions of Arp2/3 complex with actin filaments and WASP remains unclear. Here we use a recent high-resolution structure of Arp2/3 complex at a branch junction to design all-atom molecular dynamics simulations that elucidate the pathway between the active and inactive states. We ran a total of ∼4.6 microseconds of both unbiased and steered all-atom molecular dynamics simulations starting from three different binding states, including Arp2/3 complex within a branch junction, bound only to a mother filament, and alone in solution. These simulations indicate that the contacts with the mother filament are mostly insensitive to the massive rigid body motion that moves Arp2 and Arp3 into a short pitch helical (filament-like) arrangement, suggesting actin filaments alone do not stimulate the short pitch conformational change. In contrast, contacts with the mother filament stabilize subunit flattening in Arp3, an intrasubunit change that converts Arp3 from a conformation that mimics an actin monomer to one that mimics a filamentous actin subunit. Our results support a multistep activation pathway that has important implications for understanding how WASP-mediated activation allows Arp2/3 complex to assemble force-producing actin networks.
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Affiliation(s)
| | - Glen M Hocky
- Department of Chemistry, New York University; Simons Center for Computational Physical Chemistry, New York University.
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon.
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10
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Sadhu RK, Iglič A, Gov NS. A minimal cell model for lamellipodia-based cellular dynamics and migration. J Cell Sci 2023; 136:jcs260744. [PMID: 37497740 DOI: 10.1242/jcs.260744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023] Open
Abstract
One ubiquitous cellular structure for performing various tasks, such as spreading and migration over external surfaces, is the sheet-like protrusion called a lamellipodium, which propels the leading edge of the cell. Despite the detailed knowledge about the many components of this cellular structure, it is not yet fully understood how these components self-organize spatiotemporally to form lamellipodia. We review here recent theoretical works where we have demonstrated that membrane-bound protein complexes that have intrinsic curvature and recruit the protrusive forces of the cytoskeleton result in a simple, yet highly robust, organizing feedback mechanism that organizes the cytoskeleton and the membrane. This self-organization mechanism accounts for the formation of flat lamellipodia at the leading edge of cells spreading over adhesive substrates, allowing for the emergence of a polarized, motile 'minimal cell' model. The same mechanism describes how lamellipodia organize to drive robust engulfment of particles during phagocytosis and explains in simple physical terms the spreading and migration of cells over fibers and other curved surfaces. This Review highlights that despite the complexity of cellular composition, there might be simple general physical principles that are utilized by the cell to drive cellular shape dynamics.
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Affiliation(s)
- Raj Kumar Sadhu
- Institut Curie, PSL Research University, CNRS, UMR 168, Paris 75005, France
| | - Aleš Iglič
- Laboratory of Physics, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Nir S Gov
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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