1
|
Nanes BA, Bhatt K, Boujemaa-Paterski R, Azarova E, Munawar S, Rajendran D, Isogai T, Dean KM, Medalia O, Danuser G. Keratin isoform shifts modulate motility signals during wound healing. bioRxiv 2024:2023.05.04.538989. [PMID: 37205459 PMCID: PMC10187270 DOI: 10.1101/2023.05.04.538989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Keratin intermediate filaments form strong mechanical scaffolds that confer structural stability to epithelial tissues, but the reason this function requires a protein family with 54 isoforms is not understood. During skin wound healing, a shift in keratin isoform expression alters the composition of keratin filaments. How this change modulates cellular function to support epidermal remodeling remains unclear. We report an unexpected effect of keratin isoform variation on kinase signal transduction. Increased expression of wound-associated keratin 6A, but not of steady-state keratin 5, potentiated keratinocyte migration and wound closure without compromising epidermal stability by activating myosin motors. This pathway depended on isoform-specific interaction between intrinsically disordered keratin head domains and non-filamentous vimentin shuttling myosin-activating kinases. These results substantially expand the functional repertoire of intermediate filaments from their canonical role as mechanical scaffolds to include roles as isoform-tuned signaling scaffolds that organize signal transduction cascades in space and time to influence epithelial cell state.
Collapse
Affiliation(s)
- Benjamin A Nanes
- Department of Dermatology, UT Southwestern Medical Center; Dallas, TX 75390, USA
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| | - Kushal Bhatt
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| | | | - Evgenia Azarova
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
- Present address: Department of Materials Science and Engineering, Johns Hopkins University; Baltimore, MD 21218, USA
| | - Sabahat Munawar
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| | - Divya Rajendran
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| | - Tadamoto Isogai
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| | - Kevin M Dean
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich; Zurich CH-8057, Switzerland
| | - Gaudenz Danuser
- Lyda Hill Department of Bioinformatics and Cecil H and Ida Green Center for Systems Biology, UT Southwestern Medical Center; Dallas, TX 75390, USA
| |
Collapse
|
2
|
Eibauer M, Weber MS, Kronenberg-Tenga R, Beales CT, Boujemaa-Paterski R, Turgay Y, Sivagurunathan S, Kraxner J, Köster S, Goldman RD, Medalia O. Vimentin filaments integrate low-complexity domains in a complex helical structure. Nat Struct Mol Biol 2024:10.1038/s41594-024-01261-2. [PMID: 38632361 DOI: 10.1038/s41594-024-01261-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 03/01/2024] [Indexed: 04/19/2024]
Abstract
Intermediate filaments (IFs) are integral components of the cytoskeleton. They provide cells with tissue-specific mechanical properties and are involved in numerous cellular processes. Due to their intricate architecture, a 3D structure of IFs has remained elusive. Here we use cryo-focused ion-beam milling, cryo-electron microscopy and tomography to obtain a 3D structure of vimentin IFs (VIFs). VIFs assemble into a modular, intertwined and flexible helical structure of 40 α-helices in cross-section, organized into five protofibrils. Surprisingly, the intrinsically disordered head domains form a fiber in the lumen of VIFs, while the intrinsically disordered tails form lateral connections between the protofibrils. Our findings demonstrate how protein domains of low sequence complexity can complement well-folded protein domains to construct a biopolymer with striking mechanical strength and stretchability.
Collapse
Affiliation(s)
- Matthias Eibauer
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
| | - Miriam S Weber
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | | | - Charlie T Beales
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | | | - Yagmur Turgay
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Suganya Sivagurunathan
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Julia Kraxner
- Institute for X-Ray Physics, University of Göttingen, Göttingen, Germany
- MDC Berlin-Buch, Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Göttingen, Germany
| | - Robert D Goldman
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
3
|
Franz F, Tapia-Rojo R, Winograd-Katz S, Boujemaa-Paterski R, Li W, Unger T, Albeck S, Aponte-Santamaria C, Garcia-Manyes S, Medalia O, Geiger B, Gräter F. Allosteric activation of vinculin by talin. Nat Commun 2023; 14:4311. [PMID: 37463895 DOI: 10.1038/s41467-023-39646-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 06/22/2023] [Indexed: 07/20/2023] Open
Abstract
The talin-vinculin axis is a key mechanosensing component of cellular focal adhesions. How talin and vinculin respond to forces and regulate one another remains unclear. By combining single-molecule magnetic tweezers experiments, Molecular Dynamics simulations, actin-bundling assays, and adhesion assembly experiments in live cells, we here describe a two-ways allosteric network within vinculin as a regulator of the talin-vinculin interaction. We directly observe a maturation process of vinculin upon talin binding, which reinforces the binding to talin at a rate of 0.03 s-1. This allosteric transition can compete with force-induced dissociation of vinculin from talin only at forces up to 10 pN. Mimicking the allosteric activation by mutation yields a vinculin molecule that bundles actin and localizes to focal adhesions in a force-independent manner. Hence, the allosteric switch confines talin-vinculin interactions and focal adhesion build-up to intermediate force levels. The 'allosteric vinculin mutant' is a valuable molecular tool to further dissect the mechanical and biochemical signalling circuits at focal adhesions and elsewhere.
Collapse
Affiliation(s)
- Florian Franz
- Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Mathematikon, INF 205, 69120, Heidelberg, Germany
| | - Rafael Tapia-Rojo
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King's College London, Strand, WC2R 2LS London, UK.
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, London, UK.
| | - Sabina Winograd-Katz
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | | | - Wenhong Li
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Tamar Unger
- The Dana and Yossie Hollander Center for Structural Proteomics, Weizmann Institute of Science, Rehovot, Israel
| | - Shira Albeck
- The Dana and Yossie Hollander Center for Structural Proteomics, Weizmann Institute of Science, Rehovot, Israel
| | - Camilo Aponte-Santamaria
- Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Mathematikon, INF 205, 69120, Heidelberg, Germany
| | - Sergi Garcia-Manyes
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King's College London, Strand, WC2R 2LS London, UK
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, London, UK
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland.
| | - Benjamin Geiger
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel.
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies (HITS), Schloß-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany.
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Mathematikon, INF 205, 69120, Heidelberg, Germany.
- IMSEAM, Heidelberg University, INF 225, 69120, Heidelberg, Germany.
| |
Collapse
|
4
|
Geiger B, Boujemaa-Paterski R, Winograd-Katz SE, Balan Venghateri J, Chung WL, Medalia O. The Actin Network Interfacing Diverse Integrin-Mediated Adhesions. Biomolecules 2023; 13:biom13020294. [PMID: 36830665 PMCID: PMC9953007 DOI: 10.3390/biom13020294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 02/08/2023] Open
Abstract
The interface between the cellular actin network and diverse forms of integrin-mediated cell adhesions displays a unique capacity to serve as accurate chemical and mechanical sensors of the cell's microenvironment. Focal adhesion-like structures of diverse cell types, podosomes in osteoclasts, and invadopodia of invading cancer cells display distinct morphologies and apparent functions. Yet, all three share a similar composition and mode of coupling between a protrusive structure (the lamellipodium, the core actin bundle of the podosome, and the invadopodia protrusion, respectively), and a nearby adhesion site. Cytoskeletal or external forces, applied to the adhesion sites, trigger a cascade of unfolding and activation of key adhesome components (e.g., talin, vinculin, integrin), which in turn, trigger the assembly of adhesion sites and generation of adhesion-mediated signals that affect cell behavior and fate. The structural and molecular mechanisms underlying the dynamic crosstalk between the actin cytoskeleton and the adhesome network are discussed.
Collapse
Affiliation(s)
- Benjamin Geiger
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
- Correspondence: (B.G.); (O.M.)
| | - Rajaa Boujemaa-Paterski
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Sabina E. Winograd-Katz
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Jubina Balan Venghateri
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Wen-Lu Chung
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Correspondence: (B.G.); (O.M.)
| |
Collapse
|
5
|
Tapia-Rojo R, Mora M, Board S, Walker J, Boujemaa-Paterski R, Medalia O, Garcia-Manyes S. Enhanced statistical sampling reveals microscopic complexity in the talin mechanosensor folding energy landscape. Nat Phys 2023; 19:52-60. [PMID: 36660164 PMCID: PMC7614079 DOI: 10.1038/s41567-022-01808-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Statistical mechanics can describe the major conformational ensembles determining the equilibrium free-energy landscape of a folding protein. The challenge is to capture the full repertoire of low-occurrence conformations separated by high kinetic barriers that define complex landscapes. Computationally, enhanced sampling methods accelerate the exploration of molecular rare events. However, accessing the entire protein's conformational space in equilibrium experiments requires technological developments to enable extended observation times. We developed single-molecule magnetic tweezers to capture over a million individual transitions as a single talin protein unfolds and refolds under force in equilibrium. When observed at classically-probed timescales, talin folds in an apparently uncomplicated two-state manner. As the sampling time extends from minutes to days, the underlying energy landscape exhibits gradually larger signatures of complexity, involving a finite number of well-defined rare conformations. A fluctuation analysis allows us to propose plausible structures of each low-probability conformational state. The physiological relevance of each distinct conformation can be connected to the binding of the cytoskeletal protein vinculin, suggesting an extra layer of complexity in talin-mediated mechanotransduction. More generally, our experiments directly test the fundamental notion that equilibrium dynamics depend on the observation timescale.
Collapse
Affiliation(s)
- Rafael Tapia-Rojo
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, Strand, WC2R 2LS London, United Kingdom
- Corresponding authors: , ,
| | - Marc Mora
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, Strand, WC2R 2LS London, United Kingdom
- Corresponding authors: , ,
| | - Stephanie Board
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, Strand, WC2R 2LS London, United Kingdom
| | - Jane Walker
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, Strand, WC2R 2LS London, United Kingdom
| | - Rajaa Boujemaa-Paterski
- Department of Biochemistry, Zurich University, Winterhurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Ohad Medalia
- Department of Biochemistry, Zurich University, Winterhurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Sergi Garcia-Manyes
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, Strand, WC2R 2LS London, United Kingdom
- Corresponding authors: , ,
| |
Collapse
|
6
|
Boujemaa-Paterski R, Martins B, Eibauer M, Beales CT, Geiger B, Medalia O. Talin-activated vinculin interacts with branched actin networks to initiate bundles. eLife 2020; 9:e53990. [PMID: 33185186 PMCID: PMC7682986 DOI: 10.7554/elife.53990] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 11/12/2020] [Indexed: 12/18/2022] Open
Abstract
Vinculin plays a fundamental role in integrin-mediated cell adhesion. Activated by talin, it interacts with diverse adhesome components, enabling mechanical coupling between the actin cytoskeleton and the extracellular matrix. Here we studied the interactions of activated full-length vinculin with actin and the way it regulates the organization and dynamics of the Arp2/3 complex-mediated branched actin network. Through a combination of surface patterning and light microscopy experiments we show that vinculin can bundle dendritic actin networks through rapid binding and filament crosslinking. We show that vinculin promotes stable but flexible actin bundles having a mixed-polarity organization, as confirmed by cryo-electron tomography. Adhesion-like synthetic design of vinculin activation by surface-bound talin revealed that clustered vinculin can initiate and immobilize bundles from mobile Arp2/3-branched networks. Our results provide a molecular basis for coordinate actin bundle formation at nascent adhesions.
Collapse
Affiliation(s)
- Rajaa Boujemaa-Paterski
- Department of Biochemistry, University of ZurichZurichSwitzerland
- Université Grenoble AlpesGrenobleFrance
| | - Bruno Martins
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Matthias Eibauer
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Charlie T Beales
- Department of Biochemistry, University of ZurichZurichSwitzerland
| | - Benjamin Geiger
- Department of Immunology, Weizmann Institute of ScienceRehovotIsrael
| | - Ohad Medalia
- Department of Biochemistry, University of ZurichZurichSwitzerland
| |
Collapse
|
7
|
Martiel JL, Michelot A, Boujemaa-Paterski R, Blanchoin L, Berro J. Force Production by a Bundle of Growing Actin Filaments Is Limited by Its Mechanical Properties. Biophys J 2019; 118:182-192. [PMID: 31791547 DOI: 10.1016/j.bpj.2019.10.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/16/2019] [Accepted: 10/30/2019] [Indexed: 12/16/2022] Open
Abstract
Bundles of actin filaments are central to a large variety of cellular structures such as filopodia, stress fibers, cytokinetic rings, and focal adhesions. The mechanical properties of these bundles are critical for proper force transmission and force bearing. Previous mathematical modeling efforts have focused on bundles' rigidity and shape. However, it remains unknown how bundle length and buckling are controlled by external physical factors. In this work, we present a biophysical model for dynamic bundles of actin filaments submitted to an external load. In combination with in vitro motility assays of beads coated with formins, our model allowed us to characterize conditions for bead movement and bundle buckling. From the deformation profiles, we determined key biophysical properties of tethered actin bundles such as their rigidity and filament density.
Collapse
Affiliation(s)
- Jean-Louis Martiel
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; CNRS, CHU Grenoble-Alpes, Inserm, TIMC-IMAG, University Grenoble-Alpes, Grenoble, France.
| | - Alphée Michelot
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; CNRS, IBDM, Turing Centre for Living Systems, Aix Marseille University, Marseille, France
| | - Rajaa Boujemaa-Paterski
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Julien Berro
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut; Nanobiology Institute, Yale University, West Haven, Connecticut; Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut.
| |
Collapse
|
8
|
Manhart A, Icheva TA, Guerin C, Klar T, Boujemaa-Paterski R, Thery M, Blanchoin L, Mogilner A. Quantitative regulation of the dynamic steady state of actin networks. eLife 2019; 8:42413. [PMID: 30869077 PMCID: PMC6417862 DOI: 10.7554/elife.42413] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 02/26/2019] [Indexed: 12/30/2022] Open
Abstract
Principles of regulation of actin network dimensions are fundamentally important for cell functions, yet remain unclear. Using both in vitro and in silico approaches, we studied the effect of key parameters, such as actin density, ADF/Cofilin concentration and network width on the network length. In the presence of ADF/Cofilin, networks reached equilibrium and became treadmilling. At the trailing edge, the network disintegrated into large fragments. A mathematical model predicts the network length as a function of width, actin and ADF/Cofilin concentrations. Local depletion of ADF/Cofilin by binding to actin is significant, leading to wider networks growing longer. A single rate of breaking network nodes, proportional to ADF/Cofilin density and inversely proportional to the square of the actin density, can account for the disassembly dynamics. Selective disassembly of heterogeneous networks by ADF/Cofilin controls steering during motility. Our results establish general principles on how the dynamic steady state of actin network emerges from biochemical and structural feedbacks.
Collapse
Affiliation(s)
- Angelika Manhart
- Courant Institute of Mathematical Sciences, New York University, New York, United States.,Department of Biology, New York University, New York, United States
| | - Téa Aleksandra Icheva
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Christophe Guerin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Tobbias Klar
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Rajaa Boujemaa-Paterski
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France
| | - Manuel Thery
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France.,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, Paris, France
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, Grenoble, France.,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, Paris, France
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences, New York University, New York, United States.,Department of Biology, New York University, New York, United States
| |
Collapse
|
9
|
Dahan I, Sorrentino S, Boujemaa-Paterski R, Medalia O. Tiopronin-Protected Gold Nanoparticles as a Potential Marker for Cryo-EM and Tomography. Structure 2018; 26:1408-1413.e3. [PMID: 30078643 DOI: 10.1016/j.str.2018.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/03/2018] [Accepted: 06/27/2018] [Indexed: 10/28/2022]
Abstract
Gold nanoparticles (AuNPs) and their conjugation to biological samples have numerous potential applications. When combined with cryo-electron microscopy and tomography analysis, AuNPs may provide a versatile and powerful tool to identify and precisely localize proteins even when attached to cellular components. Here, we describe a general and facile approach for the synthesis of homogeneous and stable AuNPs, which can readily be conjugated to a molecule of interest and imaged by cryo-electron tomography (cryo-ET). We demonstrate the synthesis of 2.2 ± 0.45-nm tiopronin-protected AuNPs, followed by their conjugation with recombinant proteins and peptides. Visualization of the ∼2.2-nm gold-tagged peptides by cryo-ET reveals the potential use of this strategy to label and localize accessible proteins in a cellular environment with nanometric resolution.
Collapse
Affiliation(s)
- Idit Dahan
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, 84105 Beer-Sheva, Israel
| | - Simona Sorrentino
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Rajaa Boujemaa-Paterski
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Université Grenoble Alpes, 38400 Grenoble, France
| | - Ohad Medalia
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, 84105 Beer-Sheva, Israel; Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| |
Collapse
|
10
|
Boujemaa-Paterski R, Suarez C, Klar T, Zhu J, Guérin C, Mogilner A, Théry M, Blanchoin L. Network heterogeneity regulates steering in actin-based motility. Nat Commun 2017; 8:655. [PMID: 28935896 PMCID: PMC5608943 DOI: 10.1038/s41467-017-00455-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 06/29/2017] [Indexed: 11/10/2022] Open
Abstract
The growth of branched actin networks powers cell-edge protrusions and motility. A heterogeneous density of actin, which yields to a tunable cellular response, characterizes these dynamic structures. We study how actin organization controls both the rate and the steering during lamellipodium growth. We use a high-resolution surface structuration assay combined with mathematical modeling to describe the growth of a reconstituted lamellipodium. We demonstrate that local monomer depletion at the site of assembly negatively impacts the network growth rate. At the same time, network architecture tunes the protrusion efficiency, and regulates the rate of growth. One consequence of this interdependence between monomer depletion and network architecture effects is the ability of heterogeneous network to impose steering during motility. Therefore, we have established that the general principle, by which the cell can modulate the rate and the direction of a protrusion, is by varying both density and architecture of its actin network. Protrusive cellular structures contain a heterogeneous density of actin, but whether this influences motility is not known. Using an in vitro system and modelling, here the authors show that local actin monomer depletion and network architecture can tune the rate of network growth to impose steering during motility.
Collapse
Affiliation(s)
- Rajaa Boujemaa-Paterski
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Cristian Suarez
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Tobias Klar
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Jie Zhu
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY, 10012, USA
| | - Christophe Guérin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY, 10012, USA.
| | - Manuel Théry
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France. .,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, 75010, Paris, France.
| | - Laurent Blanchoin
- CytomorphoLab, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, Université Grenoble-Alpes/CEA/CNRS/INRA, 38054, Grenoble, France. .,CytomorphoLab, Hôpital Saint Louis, Institut Universitaire d'Hematologie, UMRS1160, INSERM/AP-HP/Université Paris Diderot, 75010, Paris, France.
| |
Collapse
|
11
|
Chaudhry F, Jansen S, Little K, Suarez C, Boujemaa-Paterski R, Blanchoin L, Goode BL. Autonomous and in trans functions for the two halves of Srv2/CAP in promoting actin turnover. Cytoskeleton (Hoboken) 2014; 71:351-360. [PMID: 24616256 DOI: 10.1002/cm.21170] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 02/24/2014] [Accepted: 02/25/2014] [Indexed: 01/06/2023]
Abstract
Recent evidence has suggested that Srv2/CAP (cyclase-associated protein) has two distinct functional roles in regulating actin turnover, with its N-terminus enhancing cofilin-mediated severing of actin filaments and its C-terminus catalyzing actin monomer recycling. However, it has remained unclear to what degree these two activities are coordinated by being linked in one molecule, or whether they can function autonomously. To address this, we physically divided the protein into two separate halves, N-Srv2 and C-Srv2, and asked whether they are able to function in trans both in living cells and in reconstituted assays for F-actin turnover and actin-based motility. Remarkably, in F-actin turnover assays the stimulatory effects of N-Srv2 and C-Srv2 functioning in trans were quantitatively similar to those of intact full-length Srv2. Further, in bead motility assays and in vivo, the fragments again functioned in trans, although not with the full effectiveness of intact Srv2. From these data, we conclude that the functions of the two halves of Srv2/CAP are largely autonomous, although their linkage improves coordination of the two functions in specific settings, possibly explaining why the linkage is conserved across distant plant, animal, and fungal species.
Collapse
Affiliation(s)
- Faisal Chaudhry
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, 02454, U.S.A
| | - Silvia Jansen
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, 02454, U.S.A
| | - Kristin Little
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, 02454, U.S.A
| | - Cristian Suarez
- Laboratoire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, Centre National de la Recherche Scientifique/Commissariat à l'énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier, Grenoble 38054, FRANCE
| | - Rajaa Boujemaa-Paterski
- Laboratoire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, Centre National de la Recherche Scientifique/Commissariat à l'énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier, Grenoble 38054, FRANCE
| | - Laurent Blanchoin
- Laboratoire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, Centre National de la Recherche Scientifique/Commissariat à l'énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier, Grenoble 38054, FRANCE
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, 02454, U.S.A
| |
Collapse
|
12
|
Blanchoin L, Boujemaa-Paterski R, Sykes C, Plastino J. Actin dynamics, architecture, and mechanics in cell motility. Physiol Rev 2014; 94:235-63. [PMID: 24382887 DOI: 10.1152/physrev.00018.2013] [Citation(s) in RCA: 833] [Impact Index Per Article: 83.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Tight coupling between biochemical and mechanical properties of the actin cytoskeleton drives a large range of cellular processes including polarity establishment, morphogenesis, and motility. This is possible because actin filaments are semi-flexible polymers that, in conjunction with the molecular motor myosin, can act as biological active springs or "dashpots" (in laymen's terms, shock absorbers or fluidizers) able to exert or resist against force in a cellular environment. To modulate their mechanical properties, actin filaments can organize into a variety of architectures generating a diversity of cellular organizations including branched or crosslinked networks in the lamellipodium, parallel bundles in filopodia, and antiparallel structures in contractile fibers. In this review we describe the feedback loop between biochemical and mechanical properties of actin organization at the molecular level in vitro, then we integrate this knowledge into our current understanding of cellular actin organization and its physiological roles.
Collapse
|
13
|
Abstract
The actin cytoskeleton is a fundamental player in many cellular processes. Ultrastructural studies have revealed its extremely complex organization, where actin filaments self-organize into defined and specialized structures of distinct functions and, yet, are able to selectively recruit biochemical regulators that are available in the entire cell volume. To overcome this extraordinary complexity, simplified reconstituted systems significantly improve our understanding of actin dynamics and self-organization. However, little is known regarding physical rules governing actin networks organization and to which extent network structure may direct and regulate selective interactions with specific regulators. Here, we describe the first method to direct actin filament assembly to specific 2D motifs with a finely tuned geometry and relative distribution. This method enables the study of how geometrical confinement governs actin network structural organization and how, in return, structural cues can control selective contraction by myosin motor. The protocol relies on the use of surface micropatterning and functionalization procedures in order to selectively direct actin filament assembly to specific sites of nucleation.
Collapse
Affiliation(s)
- Anne-Cécile Reymann
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Christophe Guérin
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Manuel Théry
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Laurent Blanchoin
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Rajaa Boujemaa-Paterski
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, CNRS/CEA/INRA/UJF, Grenoble, France
| |
Collapse
|
14
|
Abstract
The actin cytoskeleton is a key component of the cellular architecture. However, understanding actin organization and dynamics in vivo is a complex challenge. Reconstitution of actin structures in vitro, in simplified media, allows one to pinpoint the cellular biochemical components and their molecular interactions underlying the architecture and dynamics of the actin network. Previously, little was known about the extent to which geometrical constraints influence the dynamic ultrastructure of these networks. Therefore, in order to study the balance between biochemical and geometrical control of complex actin organization, we used the innovative methodologies of UV and laser patterning to design a wide repertoire of nucleation geometries from which we assembled branched actin networks. Using these methods, we were able to reconstitute complex actin network organizations, closely related to cellular architecture, to precisely direct and control their 3D connections. This methodology mimics the actin networks encountered in cells and can serve in the fabrication of innovative bioinspired systems.
Collapse
Affiliation(s)
- Rajaa Boujemaa-Paterski
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, France.
| | - Rémi Galland
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Cristian Suarez
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Christophe Guérin
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Manuel Théry
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, France
| | - Laurent Blanchoin
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, France
| |
Collapse
|
15
|
Reymann AC, Boujemaa-Paterski R, Martiel JL, Guérin C, Cao W, Chin HF, De La Cruz EM, Théry M, Blanchoin L. Actin network architecture can determine myosin motor activity. Science 2012; 336:1310-4. [PMID: 22679097 DOI: 10.1126/science.1221708] [Citation(s) in RCA: 225] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The organization of actin filaments into higher-ordered structures governs eukaryotic cell shape and movement. Global actin network size and architecture are maintained in a dynamic steady state through regulated assembly and disassembly. Here, we used experimentally defined actin structures in vitro to investigate how the activity of myosin motors depends on network architecture. Direct visualization of filaments revealed myosin-induced actin network deformation. During this reorganization, myosins selectively contracted and disassembled antiparallel actin structures, while parallel actin bundles remained unaffected. The local distribution of nucleation sites and the resulting orientation of actin filaments appeared to regulate the scalability of the contraction process. This "orientation selection" mechanism for selective contraction and disassembly suggests how the dynamics of the cellular actin cytoskeleton can be spatially controlled by actomyosin contractility.
Collapse
Affiliation(s)
- Anne-Cécile Reymann
- Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA)-Institut National de la Recherche Agronomique (INRA), Grenoble, France
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Reymann AC, Suarez C, Guérin C, Martiel JL, Staiger CJ, Blanchoin L, Boujemaa-Paterski R. Turnover of branched actin filament networks by stochastic fragmentation with ADF/cofilin. Mol Biol Cell 2011; 22:2541-50. [PMID: 21613547 PMCID: PMC3135479 DOI: 10.1091/mbc.e11-01-0052] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cell motility depends on the rapid assembly, aging, severing, and disassembly of actin filaments in spatially distinct zones. How a set of actin regulatory proteins that sustains actin-based force generation during motility work together in space and time remains poorly understood. We present our study of the distribution and dynamics of Arp2/3 complex, capping protein (CP), and actin-depolymerizing factor (ADF)/cofilin in actin "comet tails," using a minimal reconstituted system with nucleation-promoting factor (NPF)-coated beads. The Arp2/3 complex concentrates at nucleation sites near the beads as well as in the first actin shell. CP colocalizes with actin and is homogeneously distributed throughout the comet tail; it serves to constrain the spatial distribution of ATP/ADP-P(i) filament zones to areas near the bead. The association of ADF/cofilin with the actin network is therefore governed by kinetics of actin assembly, actin nucleotide state, and CP binding. A kinetic simulation accurately validates these observations. Following its binding to the actin networks, ADF/cofilin is able to break up the dense actin filament array of a comet tail. Stochastic severing by ADF/cofilin loosens the tight entanglement of actin filaments inside the comet tail and facilitates turnover through the macroscopic release of large portions of the aged actin network.
Collapse
Affiliation(s)
- Anne-Cécile Reymann
- Laboratoire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant, Centre National de la Recherche Scientifique/Commissariat à l'énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier, Grenoble 38054, France
| | | | | | | | | | | | | |
Collapse
|
17
|
Suarez C, Roland J, Boujemaa-Paterski R, Kang H, McCullough B, Reymann AC, Guérin C, Martiel JL, De La Cruz EM, Blanchoin L. Cofilin Tunes the Nucleotide State of Actin Filaments and Severs at Bare and Decorated Segment Boundaries. Curr Biol 2011. [DOI: 10.1016/j.cub.2011.05.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
18
|
Suarez C, Roland J, Boujemaa-Paterski R, Kang H, McCullough BR, Reymann AC, Guérin C, Martiel JL, De la Cruz EM, Blanchoin L. Cofilin tunes the nucleotide state of actin filaments and severs at bare and decorated segment boundaries. Curr Biol 2011; 21:862-8. [PMID: 21530260 DOI: 10.1016/j.cub.2011.03.064] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 03/09/2011] [Accepted: 03/24/2011] [Indexed: 11/30/2022]
Abstract
Actin-based motility demands the spatial and temporal coordination of numerous regulatory actin-binding proteins (ABPs), many of which bind with affinities that depend on the nucleotide state of actin filament. Cofilin, one of three ABPs that precisely choreograph actin assembly and organization into comet tails that drive motility in vitro, binds and stochastically severs aged ADP actin filament segments of de novo growing actin filaments. Deficiencies in methodologies to track in real time the nucleotide state of actin filaments, as well as cofilin severing, limit the molecular understanding of coupling between actin filament chemical and mechanical states and severing. We engineered a fluorescently labeled cofilin that retains actin filament binding and severing activities. Because cofilin binding depends strongly on the actin-bound nucleotide, direct visualization of fluorescent cofilin binding serves as a marker of the actin filament nucleotide state during assembly. Bound cofilin allosterically accelerates P(i) release from unoccupied filament subunits, which shortens the filament ATP/ADP-P(i) cap length by nearly an order of magnitude. Real-time visualization of filament severing indicates that fragmentation scales with and occurs preferentially at boundaries between bare and cofilin-decorated filament segments, thereby controlling the overall filament length, depending on cofilin binding density.
Collapse
Affiliation(s)
- Cristian Suarez
- Laboratoire de Physiologie Cellulaire et Végétale, Institut de Recherches en Sciences et Technologies pour le Vivant, CEA/CNRS/INRA/UJF, F-38054 Grenoble, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Blanchoin L, Boujemaa-Paterski R, Henty JL, Khurana P, Staiger CJ. Actin dynamics in plant cells: a team effort from multiple proteins orchestrates this very fast-paced game. Curr Opin Plant Biol 2010; 13:714-23. [PMID: 20970372 DOI: 10.1016/j.pbi.2010.09.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/27/2010] [Accepted: 09/23/2010] [Indexed: 05/21/2023]
Abstract
Gazing at a giant redwood tree in the Pacific Northwest, that has grown to enormous heights over centuries, does little to convince one that plants are built for speed and versatility. Even at the cellular level, a system of polymers-the cell skeleton or cytoskeleton-integrates signals and generates subcellular structures spanning scales of a few nanometers to hundreds of micrometers that coordinate cell growth. The term cytoskeleton itself connotes a stable structure. Clearly, this is not the case. Recent studies using advanced imaging modalities reveal the plant actin cytoskeleton to be a highly dynamic, ever changing assemblage of polymers. These insights along with growing evidence about the biochemical/biophysical properties of plant cytoskeletal polymers, especially those obtained by single filament imaging and reconstituted systems of purified proteins analyzed by total internal reflection fluorescence microscopy, allow the generation of a unique model for the dynamic turnover of actin filaments, termed stochastic dynamics. Here, we review several significant advances and highlight opportunities that will position plants at the vanguard of research on actin organization and turnover. A challenge for the future will be to apply the power of reverse-genetics in several model organisms to test the molecular details of this new model.
Collapse
Affiliation(s)
- Laurent Blanchoin
- Institut de Recherches en Technologies et Sciences pour le Vivant - iRTSV, Laboratoire de Phyiologie Cellulaire et Végétale, Commissariat à l'Energie Atomique /Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, CEA Grenoble, F38054, Grenoble, France.
| | | | | | | | | |
Collapse
|
20
|
Reymann AC, Martiel JL, Cambier T, Blanchoin L, Boujemaa-Paterski R, Théry M. Nucleation geometry governs ordered actin networks structures. Nat Mater 2010; 9:827-32. [PMID: 20852617 DOI: 10.1038/nmat2855] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 08/11/2010] [Indexed: 05/16/2023]
Abstract
Actin filaments constitute one of the main components of cell cytoskeleton. Assembled into bundles in filopodia or in stress fibres, they play a pivotal role in eukaryotes during cell morphogenesis, adhesion and motility. The bundle emergence has been extensively related to specific actin regulators in vivo. Such dynamic modulation was also highlighted by biochemical reconstitution of the actin-network assembly, in bulk solution or with biomimetic devices. However, the question of how geometrical boundaries, such as those encountered in cells, affect the dynamic formation of highly ordered actin structures remains poorly studied. Here we demonstrate that the nucleation geometry in itself can be the principal determinant of actin-network architecture. We developed a micropatterning method that enables the spatial control of actin nucleation sites for in vitro assays. Shape, orientation and distance between nucleation regions control filament orientation and length, filament-filament interactions and filopodium-like bundle formation. Modelling of filament growth and interactions demonstrates that basic mechanical and probabilistic laws govern actin assembly in higher-order structures.
Collapse
Affiliation(s)
- Anne-Cécile Reymann
- Institut de Recherches en Technologies et Sciences pour le Vivant, iRTSV, Laboratoire de Physiologie Cellulaire et Végétale, CNRS/CEA/INRA/UJF, Grenoble, 38054, France
| | | | | | | | | | | |
Collapse
|
21
|
Abstract
In this issue of Chemistry and Biology, Rizvi and colleagues indentify a small molecule that inhibits formin-mediated actin assembly. Together with recently characterized inhibitors of the Arp2/3 complex (Nolen et al., 2009) and formins (Gauvin et al., 2009), these small molecules provide useful laboratory tools to dissect the link between actin nucleators and actin-based structures in living cells.
Collapse
Affiliation(s)
- Laurent Blanchoin
- Institut de Recherches en Technologies et Sciences pour le Vivant, CNRS/CEA/INRA/UJF, Grenoble, France.
| | | |
Collapse
|
22
|
Achard V, Martiel JL, Michelot A, Guérin C, Reymann AC, Blanchoin L, Boujemaa-Paterski R. A “Primer”-Based Mechanism Underlies Branched Actin Filament Network Formation and Motility. Curr Biol 2010; 20:423-8. [DOI: 10.1016/j.cub.2009.12.056] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 12/22/2009] [Accepted: 12/23/2009] [Indexed: 10/19/2022]
|
23
|
Michelot A, Berro J, Guérin C, Boujemaa-Paterski R, Staiger CJ, Martiel JL, Blanchoin L. Actin-Filament Stochastic Dynamics Mediated by ADF/Cofilin. Curr Biol 2007; 17:825-33. [PMID: 17493813 DOI: 10.1016/j.cub.2007.04.037] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 03/16/2007] [Accepted: 04/12/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND The rapid dynamics of actin filaments is a fundamental process that powers a large number of cellular functions. However, the basic mechanisms that control and coordinate such dynamics remain a central question in cell biology. To reach beyond simply defining the inventory of molecules that control actin dynamics and to understand how these proteins act synergistically to modulate filament turnover, we combined evanescent-wave microscopy with a biomimetic system and followed the behavior of single actin filaments in the presence of a physiologically relevant mixture of accessory proteins. This approach allows for the real-time visualization of actin polymerization and age-dependent filament severing. RESULTS In the presence of actin-depolymerizing factor (ADF)/cofilin and profilin, actin filaments with a processive formin attached at their barbed ends were observed to oscillate between stochastic growth and shrinkage phases. Fragmentation of continuously growing actin filaments by ADF/cofilin is the key mechanism modulating the prominent and frequent shortening events. The net effect of continuous actin polymerization, driven by a processive formin that uses profilin-actin, and of ADF/cofilin-mediating severing that trims the aged ends of the growing filaments is an up to 155-fold increase in the rate of actin-filament turnover in vitro in comparison to that of actin alone. Lateral contact between actin filaments dampens the dynamics and favors actin-cable formation. A kinetic simulation accurately validates these observations. CONCLUSIONS Our proposed mechanism for the control of actin dynamics is dominated by ADF/cofilin-mediated filament severing that induces a stochastic behavior upon individual actin filaments. When combined with a selection process that stabilizes filaments in bundles, this mechanism could account for the emergence and extension of actin-based structures in cells.
Collapse
Affiliation(s)
- Alphée Michelot
- Institut de Recherches en Technologie et Sciences pour le Vivant, Laboratoire de Physiologie Cellulaire Végétale, CEA Grenoble, Université Joseph Fourier, 17 rue des Martyrs, F38054 Grenoble, France
| | | | | | | | | | | | | |
Collapse
|
24
|
Boujemaa-Paterski R, Gouin E, Hansen G, Samarin S, Le Clainche C, Didry D, Dehoux P, Cossart P, Kocks C, Carlier MF, Pantaloni D. Listeria protein ActA mimics WASp family proteins: it activates filament barbed end branching by Arp2/3 complex. Biochemistry 2001; 40:11390-404. [PMID: 11560487 DOI: 10.1021/bi010486b] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Actin-based propulsion of the bacteria Listeria and Shigella mimics the forward movement of the leading edge of motile cells. While Shigella harnesses the eukaryotic protein N-WASp to stimulate actin polymerization and filament branching through Arp2/3 complex, the Listeria surface protein ActA directly activates Arp2/3 complex by an unknown mechanism. Here we show that the N-terminal domain of ActA binds one actin monomer, in a profilin-like fashion, and Arp2/3 complex and mimics the C-terminal domain of WASp family proteins in catalyzing filament barbed end branching by Arp2/3 complex. No evidence is found for side branching of filaments by ActA-activated Arp2/3 complex. Mutations in the conserved acidic (41)DEWEEE(46) and basic (146)KKRRK(150) regions of ActA affect Arp2/3 binding but not G-actin binding. The motility properties of wild-type and mutated Listeria strains in living cells and in the medium reconstituted from pure proteins confirm the conclusions of biochemical experiments. Filament branching is followed by rapid debranching. Debranching is 3-4-fold faster when Arp2/3 is activated by ActA than by the C-terminal domain of N-WASp. VASP is required for efficient propulsion of ActA-coated beads in the reconstituted motility medium, but it does not affect the rates of barbed end branching/debranching by ActA-activated Arp2/3 nor the capping of filaments. VASP therefore affects another still unidentified biochemical reaction that plays an important role in actin-based movement.
Collapse
|