1
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Tsai FC, Guérin G, Pernier J, Bassereau P. Actin-membrane linkers: Insights from synthetic reconstituted systems. Eur J Cell Biol 2024; 103:151402. [PMID: 38461706 DOI: 10.1016/j.ejcb.2024.151402] [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: 12/03/2023] [Revised: 02/10/2024] [Accepted: 02/28/2024] [Indexed: 03/12/2024] Open
Abstract
At the cell surface, the actin cytoskeleton and the plasma membrane interact reciprocally in a variety of processes related to the remodeling of the cell surface. The actin cytoskeleton has been known to modulate membrane organization and reshape the membrane. To this end, actin-membrane linking molecules play a major role in regulating actin assembly and spatially direct the interaction between the actin cytoskeleton and the membrane. While studies in cells have provided a wealth of knowledge on the molecular composition and interactions of the actin-membrane interface, the complex molecular interactions make it challenging to elucidate the precise actions of the actin-membrane linkers at the interface. Synthetic reconstituted systems, consisting of model membranes and purified proteins, have been a powerful approach to elucidate how actin-membrane linkers direct actin assembly to drive membrane shape changes. In this review, we will focus only on several actin-membrane linkers that have been studied by using reconstitution systems. We will discuss the design principles of these reconstitution systems and how they have contributed to the understanding of the cellular functions of actin-membrane linkers. Finally, we will provide a perspective on future research directions in understanding the intricate actin-membrane interaction.
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Affiliation(s)
- Feng-Ching Tsai
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Physics of Cells and Cancer, Paris 75005, France.
| | - Gwendal Guérin
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Physics of Cells and Cancer, Paris 75005, France
| | - Julien Pernier
- Tumor Cell Dynamics Unit, Inserm U1279, Gustave Roussy Institute, Université Paris-Saclay, Villejuif 94800, France
| | - Patricia Bassereau
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Physics of Cells and Cancer, Paris 75005, France.
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2
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Kovács Z, Bajusz C, Szabó A, Borkúti P, Vedelek B, Benke R, Lipinszki Z, Kristó I, Vilmos P. A bipartite NLS motif mediates the nuclear import of Drosophila moesin. Front Cell Dev Biol 2024; 12:1206067. [PMID: 38450250 PMCID: PMC10915024 DOI: 10.3389/fcell.2024.1206067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 02/08/2024] [Indexed: 03/08/2024] Open
Abstract
The ERM protein family, which consists of three closely related proteins in vertebrates, ezrin, radixin, and moesin (ERM), is an ancient and important group of cytoplasmic actin-binding and organizing proteins. With their FERM domain, ERMs bind various transmembrane proteins and anchor them to the actin cortex through their C-terminal F-actin binding domain, thus they are major regulators of actin dynamics in the cell. ERMs participate in many fundamental cellular processes, such as phagocytosis, microvilli formation, T-cell activation and tumor metastasis. We have previously shown that, besides its cytoplasmic activities, the single ERM protein of Drosophila melanogaster, moesin, is also present in the cell nucleus, where it participates in gene expression and mRNA export. Here we study the mechanism by which moesin enters the nucleus. We show that the nuclear import of moesin is an NLS-mediated, active process. The nuclear localization sequence of the moesin protein is an evolutionarily highly conserved, conventional bipartite motif located on the surface of the FERM domain. Our experiments also reveal that the nuclear import of moesin does not require PIP2 binding or protein activation, and occurs in monomeric form. We propose, that the balance between the phosphorylated and non-phosphorylated protein pools determines the degree of nuclear import of moesin.
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Affiliation(s)
- Zoltán Kovács
- HUN-REN Biological Research Centre, Szeged, Hungary
- Doctoral School of Multidisciplinary Medical Science, University of Szeged, Szeged, Hungary
| | - Csaba Bajusz
- HUN-REN Biological Research Centre, Szeged, Hungary
| | - Anikó Szabó
- HUN-REN Biological Research Centre, Szeged, Hungary
| | | | | | - Réka Benke
- HUN-REN Biological Research Centre, Szeged, Hungary
| | - Zoltán Lipinszki
- HUN-REN Biological Research Centre, Institute of Biochemistry, MTA SZBK Lendület Laboratory of Cell Cycle Regulation, Szeged, Hungary
| | | | - Péter Vilmos
- HUN-REN Biological Research Centre, Szeged, Hungary
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3
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Parent SE, Luu O, Bruce AEE, Winklbauer R. Two-phase kinetics and cell cortex elastic behavior in Xenopus gastrula cell-cell adhesion. Dev Cell 2024; 59:141-155.e6. [PMID: 38091998 DOI: 10.1016/j.devcel.2023.11.014] [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: 06/17/2022] [Revised: 06/21/2023] [Accepted: 11/13/2023] [Indexed: 01/11/2024]
Abstract
Morphogenetic movements during animal development involve repeated making and breaking of cell-cell contacts. Recent biophysical models of cell-cell adhesion integrate adhesion molecule interactions and cortical cytoskeletal tension modulation, describing equilibrium states for established contacts. We extend this emerging unified concept of adhesion to contact formation kinetics, showing that aggregating Xenopus embryonic cells rapidly achieve Ca2+-independent low-contact states. Subsequent transitions to cadherin-dependent high-contact states show rapid decreases in contact cortical F-actin levels but slow contact area growth. We developed a biophysical model that predicted contact growth quantitatively from known cellular and cytoskeletal parameters, revealing that elastic resistance to deformation and cytoskeletal network turnover are essential determinants of adhesion kinetics. Characteristic time scales of contact growth to low and high states differ by an order of magnitude, being at a few minutes and tens of minutes, respectively, thus providing insight into the timescales of cell-rearrangement-dependent tissue movements.
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Affiliation(s)
- Serge E Parent
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
| | - Olivia Luu
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Ashley E E Bruce
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
| | - Rudolf Winklbauer
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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4
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Guo L, Jacob S, Manne BK, Kolawole EM, Guo S, Wang X, Murray D, Tugolukova EA, Portier I, Kosaka Y, Barba C, Rondina MT, Evavold B, Morley C, Bhatlekar S, Bray PF. Actin-bundling protein L-plastin promotes megakaryocyte rigidity and dampens proplatelet formation. Haematologica 2024; 109:331-336. [PMID: 37439340 PMCID: PMC10772514 DOI: 10.3324/haematol.2023.283016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023] Open
Abstract
Not available.
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Affiliation(s)
- Li Guo
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT; Division of Hematology and Hematologic Malignancies, Department of Internal Medicine, University of Utah, Salt Lake City, UT; Bloodworks Research Institute, Seattle, WA; Hematology Division, University of Washington, Seattle, WA
| | - Shancy Jacob
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Bhanu Kanth Manne
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | | | - Siqi Guo
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT; Applied Mathematics, Department of Mathematics, University of Utah, Salt Lake City, UT
| | - Xiang Wang
- HSC Cell Imaging Core, School of Medicine, University of Utah, Salt Lake City, UT
| | - Darian Murray
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Emilia A Tugolukova
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Irina Portier
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Yasuhiro Kosaka
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Cindy Barba
- Department of Pathology, University of Utah, Salt Lake City, UT
| | - Matthew T Rondina
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT; Department of Pathology, University of Utah, Salt Lake City, UT; Department of Internal medicine, University of Utah, Salt Lake City, UT; George E. Wahlen Department of Veterans Affairs Medical Center, Department of Internal Medicine, and Geriatric Research, Education, and Clinical Center (GRECC), Salt Lake City, UT
| | - Brian Evavold
- Department of Pathology, University of Utah, Salt Lake City, UT
| | - Celeste Morley
- Pediatrics, Infectious Diseases, Washington University, St. Louis, MO; Pathology and Immunology, Washington University, St. Louis, MO
| | - Seema Bhatlekar
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT.
| | - Paul F Bray
- Program in Molecular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, UT; Division of Hematology and Hematologic Malignancies, Department of Internal Medicine, University of Utah, Salt Lake City, UT.
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5
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Asante-Asamani E, Dalton M, Brazill D, Strychalski W. Modeling the dynamics of actin and myosin during bleb stabilization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.564082. [PMID: 37961169 PMCID: PMC10634845 DOI: 10.1101/2023.10.26.564082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The actin cortex is very dynamic during migration of eukaryotes. In cells that use blebs as leading-edge protrusions, the cortex reforms beneath the cell membrane (bleb cortex) and completely disassembles at the site of bleb initiation. Remnants of the actin cortex at the site of bleb nucleation are referred to as the actin scar. We refer to the combined process of cortex reformation along with the degradation of the actin scar during bleb-based cell migration as bleb stabilization. The molecular factors that regulate the dynamic reorganization of the cortex are not fully understood. Myosin motor protein activity has been shown to be necessary for blebbing, with its major role associated with pressure generation to drive bleb expansion. Here, we examine the role of myosin in regulating cortex dynamics during bleb stabilization. Analysis of microscopy data from protein localization experiments in Dictyostelium discoideum cells reveals a rapid formation of the bleb's cortex with a delay in myosin accumulation. In the degrading actin scar, myosin is observed to accumulate before active degradation of the cortex begins. Through a combination of mathematical modeling and data fitting, we identify that myosin helps regulate the equilibrium concentration of actin in the bleb cortex during its reformation by increasing its dissasembly rate. Our modeling and analysis also suggests that cortex degradation is driven primarily by an exponential decrease in actin assembly rate rather than increased myosin activity. We attribute the decrease in actin assembly to the separation of the cell membrane from the cortex after bleb nucleation.
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Affiliation(s)
| | - Mackenzie Dalton
- Department of Mathematics, Clarkson University, Clarkson, Potsdam, NY 13699
| | | | - Wanda Strychalski
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, OH 44106
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6
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Quiroga X, Walani N, Disanza A, Chavero A, Mittens A, Tebar F, Trepat X, Parton RG, Geli MI, Scita G, Arroyo M, Le Roux AL, Roca-Cusachs P. A mechanosensing mechanism controls plasma membrane shape homeostasis at the nanoscale. eLife 2023; 12:e72316. [PMID: 37747150 PMCID: PMC10569792 DOI: 10.7554/elife.72316] [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: 07/19/2021] [Accepted: 09/24/2023] [Indexed: 09/26/2023] Open
Abstract
As cells migrate and experience forces from their surroundings, they constantly undergo mechanical deformations which reshape their plasma membrane (PM). To maintain homeostasis, cells need to detect and restore such changes, not only in terms of overall PM area and tension as previously described, but also in terms of local, nanoscale topography. Here, we describe a novel phenomenon, by which cells sense and restore mechanically induced PM nanoscale deformations. We show that cell stretch and subsequent compression reshape the PM in a way that generates local membrane evaginations in the 100 nm scale. These evaginations are recognized by I-BAR proteins, which triggers a burst of actin polymerization mediated by Rac1 and Arp2/3. The actin polymerization burst subsequently re-flattens the evagination, completing the mechanochemical feedback loop. Our results demonstrate a new mechanosensing mechanism for PM shape homeostasis, with potential applicability in different physiological scenarios.
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Affiliation(s)
- Xarxa Quiroga
- Institute for Bioengineering of Catalonia, the Barcelona Institute of Technology (BIST)BarcelonaSpain
- Departament de Biomedicina, Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de BarcelonaBarcelonaSpain
| | - Nikhil Walani
- Department of Applied Mechanics, IIT DelhiNew DelhiIndia
| | - Andrea Disanza
- IFOM ETS - The AIRC Institute of Molecular OncologyMilanItaly
| | - Albert Chavero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de BarcelonaBarcelonaSpain
| | - Alexandra Mittens
- Institute for Bioengineering of Catalonia, the Barcelona Institute of Technology (BIST)BarcelonaSpain
| | - Francesc Tebar
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de BarcelonaBarcelonaSpain
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia, the Barcelona Institute of Technology (BIST)BarcelonaSpain
| | - Robert G Parton
- Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, University of QueenslandBrisbaneAustralia
| | | | - Giorgio Scita
- IFOM ETS - The AIRC Institute of Molecular OncologyMilanItaly
- Department of Oncology and Haemato-Oncology, University of MilanMilanItaly
| | - Marino Arroyo
- Institute for Bioengineering of Catalonia, the Barcelona Institute of Technology (BIST)BarcelonaSpain
- Universitat Politècnica de Catalunya (UPC), Campus Nord, Carrer de Jordi GironaBarcelonaSpain
- Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE)BarcelonaSpain
| | - Anabel-Lise Le Roux
- Institute for Bioengineering of Catalonia, the Barcelona Institute of Technology (BIST)BarcelonaSpain
| | - Pere Roca-Cusachs
- Institute for Bioengineering of Catalonia, the Barcelona Institute of Technology (BIST)BarcelonaSpain
- Departament de Biomedicina, Unitat de Biofísica i Bioenginyeria, Facultat de Medicina i Ciències de la Salut, Universitat de BarcelonaBarcelonaSpain
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7
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Baldauf L, Frey F, Arribas Perez M, Idema T, Koenderink GH. Branched actin cortices reconstituted in vesicles sense membrane curvature. Biophys J 2023:S0006-3495(23)00124-8. [PMID: 36806830 DOI: 10.1016/j.bpj.2023.02.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/16/2022] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
The actin cortex is a complex cytoskeletal machinery that drives and responds to changes in cell shape. It must generate or adapt to plasma membrane curvature to facilitate diverse functions such as cell division, migration, and phagocytosis. Due to the complex molecular makeup of the actin cortex, it remains unclear whether actin networks are inherently able to sense and generate membrane curvature, or whether they rely on their diverse binding partners to accomplish this. Here, we show that curvature sensing is an inherent capability of branched actin networks nucleated by Arp2/3 and VCA. We develop a robust method to encapsulate actin inside giant unilamellar vesicles (GUVs) and assemble an actin cortex at the inner surface of the GUV membrane. We show that actin forms a uniform and thin cortical layer when present at high concentration and distinct patches associated with negative membrane curvature at low concentration. Serendipitously, we find that the GUV production method also produces dumbbell-shaped GUVs, which we explain using mathematical modeling in terms of membrane hemifusion of nested GUVs. We find that branched actin networks preferentially assemble at the neck of the dumbbells, which possess a micrometer-range convex curvature comparable with the curvature of the actin patches found in spherical GUVs. Minimal branched actin networks can thus sense membrane curvature, which may help mammalian cells to robustly recruit actin to curved membranes to facilitate diverse cellular functions such as cytokinesis and migration.
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Affiliation(s)
- Lucia Baldauf
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Felix Frey
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Marcos Arribas Perez
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Timon Idema
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands.
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8
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Senju Y, Hibino E. Moesin-ezrin-radixin-like protein merlin: Its conserved and distinct functions from those of ERM proteins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184076. [PMID: 36302494 DOI: 10.1016/j.bbamem.2022.184076] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 10/13/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Yosuke Senju
- Research Institute for Interdisciplinary Science (RIIS), Okayama University, Okayama, Japan.
| | - Emi Hibino
- Graduate School of Pharmaceutical Sciences, Nagoya University, Aichi, Japan
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9
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Aufderhorst-Roberts A, Staykova M. Scratching beyond the surface - minimal actin assemblies as tools to elucidate mechanical reinforcement and shape change. Emerg Top Life Sci 2022; 6:ETLS20220052. [PMID: 36541184 PMCID: PMC9788373 DOI: 10.1042/etls20220052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022]
Abstract
The interaction between the actin cytoskeleton and the plasma membrane in eukaryotic cells is integral to a large number of functions such as shape change, mechanical reinforcement and contraction. These phenomena are driven by the architectural regulation of a thin actin network, directly beneath the membrane through interactions with a variety of binding proteins, membrane anchoring proteins and molecular motors. An increasingly common approach to understanding the mechanisms that drive these processes is to build model systems from reconstituted lipids, actin filaments and associated actin-binding proteins. Here we review recent progress in this field, with a particular emphasis on how the actin cytoskeleton provides mechanical reinforcement, drives shape change and induces contraction. Finally, we discuss potential future developments in the field, which would allow the extension of these techniques to more complex cellular processes.
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Affiliation(s)
| | - Margarita Staykova
- Centre for Materials Physics, Department of Physics, Durham University, Durham DH1 3LE, U.K
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10
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Qu Y, Alves‐Silva J, Gupta K, Hahn I, Parkin J, Sánchez‐Soriano N, Prokop A. Re-evaluating the actin-dependence of spectraplakin functions during axon growth and maintenance. Dev Neurobiol 2022; 82:288-307. [PMID: 35333003 PMCID: PMC9320987 DOI: 10.1002/dneu.22873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/30/2022] [Accepted: 03/07/2022] [Indexed: 11/11/2022]
Abstract
Axons are the long and slender processes of neurons constituting the biological cables that wire the nervous system. The growth and maintenance of axons require loose microtubule bundles that extend through their entire length. Understanding microtubule regulation is therefore an essential aspect of axon biology. Key regulators of neuronal microtubules are the spectraplakins, a well-conserved family of cytoskeletal cross-linkers that underlie neuropathies in mouse and humans. Spectraplakin deficiency in mouse or Drosophila causes severe decay of microtubule bundles and reduced axon growth. The underlying mechanisms are best understood for Drosophila's spectraplakin Short stop (Shot) and believed to involve cytoskeletal cross-linkage: Shot's binding to microtubules and Eb1 via its C-terminus has been thoroughly investigated, whereas its F-actin interaction via N-terminal calponin homology (CH) domains is little understood. Here, we have gained new understanding by showing that the F-actin interaction must be finely balanced: altering the properties of F-actin networks or deleting/exchanging Shot's CH domains induces changes in Shot function-with a Lifeact-containing Shot variant causing remarkable remodeling of neuronal microtubules. In addition to actin-microtubule (MT) cross-linkage, we find strong indications that Shot executes redundant MT bundle-promoting roles that are F-actin-independent. We argue that these likely involve the neuronal Shot-PH isoform, which is characterized by a large, unexplored central plakin repeat region (PRR) similarly existing also in mammalian spectraplakins.
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Affiliation(s)
- Yue Qu
- Manchester Academic Health Science CentreFaculty of BiologyMedicine and HealthSchool of Biology, The University of ManchesterManchesterUK
- Present address:
Division of Nutritional Sciences, College of Human Ecology, Cornell University, Ithaca, USA
| | - Juliana Alves‐Silva
- Manchester Academic Health Science CentreFaculty of BiologyMedicine and HealthSchool of Biology, The University of ManchesterManchesterUK
- Present address:
Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Kriti Gupta
- Department of Molecular Physiology & Cell SignallingInstitute of SystemsMolecular & Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - Ines Hahn
- Manchester Academic Health Science CentreFaculty of BiologyMedicine and HealthSchool of Biology, The University of ManchesterManchesterUK
| | - Jill Parkin
- Manchester Academic Health Science CentreFaculty of BiologyMedicine and HealthSchool of Biology, The University of ManchesterManchesterUK
| | - Natalia Sánchez‐Soriano
- Department of Molecular Physiology & Cell SignallingInstitute of SystemsMolecular & Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - Andreas Prokop
- Manchester Academic Health Science CentreFaculty of BiologyMedicine and HealthSchool of Biology, The University of ManchesterManchesterUK
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11
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Muñoz-López MJ, Kim H, Mori Y. A Reduced 1D Stochastic Model of Bleb-driven Cell Migration. Biophys J 2022; 121:1881-1896. [PMID: 35450826 PMCID: PMC9199100 DOI: 10.1016/j.bpj.2022.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/01/2021] [Accepted: 04/14/2022] [Indexed: 11/02/2022] Open
Abstract
Blebs are pressure-driven protrusions that have been observed in cells undergoing apoptosis, cytokinesis, or migration, including tumour cells that use blebs to escape their organs of origin. Here, we present a minimal 1D model of bleb-driven cell motion that combines a simple mechanical model with turnover kinetics of the actin cortex and adhesions between the membrane and the cortex. The deterministic version of this model is used to study the properties of individual blebbing events. We further introduce stochastic turnover of the adhesions, which allows for spontaneous initiation of repeated blebbing events, thus leading to sustained cell travel. We explore how the main parameters of the system control the properties of the blebbing events and the speed of cell travel. Finally, we derive a further simplification by deriving a Langevin approximation to this stochastic model.
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Affiliation(s)
- María Jesús Muñoz-López
- Department of Mathematics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hyunjoong Kim
- Department of Mathematics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yoichiro Mori
- Department of Mathematics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
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12
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A biophysical perspective of the regulatory mechanisms of ezrin/radixin/moesin proteins. Biophys Rev 2022; 14:199-208. [PMID: 35340609 PMCID: PMC8921360 DOI: 10.1007/s12551-021-00928-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/14/2021] [Indexed: 02/08/2023] Open
Abstract
Many signal transductions resulting from ligand-receptor interactions occur at the cell surface. These signaling pathways play essential roles in cell polarization, membrane morphogenesis, and the modulation of membrane tension at the cell surface. However, due to the large number of membrane-binding proteins, including actin-membrane linkers, and transmembrane proteins present at the cell surface, the molecular mechanisms underlying the regulation at the cell surface are yet unclear. Here, we describe the molecular functions of one of the key players at the cell surface, ezrin/radixin/moesin (ERM) proteins from a biophysical point of view. We focus our discussion on biophysical properties of ERM proteins revealed by using biophysical tools in live cells and in vitro reconstitution systems. We first describe the structural properties of ERM proteins and then discuss the interactions of ERM proteins with PI(4,5)P2 and the actin cytoskeleton. These properties of ERM proteins revealed by using biophysical approaches have led to a better understanding of their physiological functions in cells and tissues. Supplementary Information The online version contains supplementary material available at 10.1007/s12551-021-00928-0.
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13
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Shiomi A, Nagao K, Yokota N, Tsuchiya M, Kato U, Juni N, Hara Y, Mori MX, Mori Y, Ui-Tei K, Murate M, Kobayashi T, Nishino Y, Miyazawa A, Yamamoto A, Suzuki R, Kaufmann S, Tanaka M, Tatsumi K, Nakabe K, Shintaku H, Yesylevsky S, Bogdanov M, Umeda M. Extreme deformability of insect cell membranes is governed by phospholipid scrambling. Cell Rep 2021; 35:109219. [PMID: 34107250 DOI: 10.1016/j.celrep.2021.109219] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 04/02/2021] [Accepted: 05/13/2021] [Indexed: 10/21/2022] Open
Abstract
Organization of dynamic cellular structure is crucial for a variety of cellular functions. In this study, we report that Drosophila and Aedes have highly elastic cell membranes with extremely low membrane tension and high resistance to mechanical stress. In contrast to other eukaryotic cells, phospholipids are symmetrically distributed between the bilayer leaflets of the insect plasma membrane, where phospholipid scramblase (XKR) that disrupts the lipid asymmetry is constitutively active. We also demonstrate that XKR-facilitated phospholipid scrambling promotes the deformability of cell membranes by regulating both actin cortex dynamics and mechanical properties of the phospholipid bilayer. Moreover, XKR-mediated construction of elastic cell membranes is essential for hemocyte circulation in the Drosophila cardiovascular system. Deformation of mammalian cells is also enhanced by the expression of Aedes XKR, and thus phospholipid scrambling may contribute to formation of highly deformable cell membranes in a variety of living eukaryotic cells.
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Affiliation(s)
- Akifumi Shiomi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Kohjiro Nagao
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan.
| | - Nobuhiro Yokota
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Masaki Tsuchiya
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Utako Kato
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Naoto Juni
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Yuji Hara
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Masayuki X Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan
| | - Kumiko Ui-Tei
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Motohide Murate
- UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74 Route du Rhin, 67401 Illkirch, France
| | - Toshihide Kobayashi
- UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74 Route du Rhin, 67401 Illkirch, France
| | - Yuri Nishino
- Graduate School of Life Science, University of Hyogo, Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Atsuo Miyazawa
- Graduate School of Life Science, University of Hyogo, Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
| | - Akihisa Yamamoto
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
| | - Ryo Suzuki
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
| | - Stefan Kaufmann
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120 Heidelberg, Germany
| | - Motomu Tanaka
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan; Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120 Heidelberg, Germany
| | - Kazuya Tatsumi
- Department of Mechanical Engineering and Science, Kyoto University, Katsura, Kyoto 615-8540, Japan
| | - Kazuyoshi Nakabe
- Department of Mechanical Engineering and Science, Kyoto University, Katsura, Kyoto 615-8540, Japan
| | - Hirofumi Shintaku
- Microfluidics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Semen Yesylevsky
- Laboratoire Chrono Environnement UMR CNRS 6249, Université de Bourgogne Franche-Comté, 16 Route de Gray, 25030 Besançon Cedex, France; Department of Physics of Biological Systems, Institute of Physics of the National Academy of Sciences of Ukraine, Prospect Nauky 46, 03680 Kyiv, Ukraine
| | - Mikhail Bogdanov
- Department of Biochemistry & Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, 6431 Fannin, Houston, TX 77030, USA
| | - Masato Umeda
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan.
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14
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Molecular basis of functional exchangeability between ezrin and other actin-membrane associated proteins during cytokinesis. Exp Cell Res 2021; 403:112600. [PMID: 33862101 DOI: 10.1016/j.yexcr.2021.112600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/03/2021] [Accepted: 04/05/2021] [Indexed: 01/09/2023]
Abstract
The mechanism that mediates the interaction between the contractile ring and the plasma membrane during cytokinesis remains elusive. We previously found that ERM (Ezrin/Radixin/Moesin) proteins, which usually mediate cellular pole contraction, become over-accumulated at the cell equator and support furrow ingression upon the loss of other actin-membrane associated proteins, anillin and supervillin. In this study, we addressed the molecular basis of the exchangeability between ezrin and other actin-membrane associated proteins in mediating cortical contraction during cytokinesis. We found that depletion of anillin and supervillin caused over-accumulation of the membrane-associated FERM domain and actin-binding C-terminal domain (C-term) of ezrin at the cleavage furrow, respectively. This finding suggests that ezrin differentially shares its binding sites with these proteins on the actin cytoskeleton or inner membrane surface. Using chimeric mutants, we found that ezrin C-term, but not the FERM domain, can substitute for the corresponding anillin domains in cytokinesis and cell proliferation. On the other hand, either the membrane-associated or the actin/myosin-binding domains of anillin could not substitute for the corresponding ezrin domains in controlling cortical blebbing at the cell poles. Our results highlight specific designs of actin- or membrane-associated moieties of different actin-membrane associated proteins with limited exchangeability, which enables them to support diverse cortical activities on the shared actin-membrane interface during cytokinesis.
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15
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Dirks C, Striewski P, Wirth B, Aalto A, Olguin-Olguin A. A mathematical model for bleb regulation in zebrafish primordial germ cells. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2021; 38:218-254. [PMID: 33601409 DOI: 10.1093/imammb/dqab002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/12/2021] [Accepted: 01/24/2021] [Indexed: 01/02/2023]
Abstract
Blebs are cell protrusions generated by local membrane-cortex detachments followed by expansion of the plasma membrane. Blebs are formed by some migrating cells, e.g. primordial germ cells of the zebrafish. While blebs occur randomly at each part of the membrane in unpolarized cells, a polarization process guarantees the occurrence of blebs at a preferential site and thereby facilitates migration toward a specified direction. Little is known about the factors involved in the controlled and directed bleb generation, yet recent studies revealed the influence of an intracellular flow and the stabilizing role of the membrane-cortex linker molecule Ezrin. Based on this information, we develop and analyse a coupled bulk-surface model describing a potential cellular mechanism by which a bleb could be induced at a controlled site. The model rests upon intracellular Darcy flow and a diffusion-advection-reaction system, describing the temporal evolution from a homogeneous to a strongly anisotropic Ezrin distribution. We prove the well-posedness of the mathematical model and show that simulations qualitatively correspond to experimental observations, suggesting that indeed the interaction of an intracellular flow with membrane proteins can be the cause of the Ezrin redistribution accompanying bleb formation.
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Affiliation(s)
- Carolin Dirks
- WWU Münster FB 10 Mathematik und Informatik, Institute for Analysis and Numerics, 48149 Münster, Germany
| | - Paul Striewski
- WWU Münster FB 10 Mathematik und Informatik, Institute for Analysis and Numerics, 48149 Münster, Germany
| | - Benedikt Wirth
- WWU Münster FB 10 Mathematik und Informatik, Institute for Analysis and Numerics, 48149 Münster, Germany
| | - Anne Aalto
- WWU Münster FB 13 Biologie, Institute of Cell Biology, Center for Molecular Biology of Inflammation, 48149 Münster, Germany
| | - Adan Olguin-Olguin
- WWU Münster FB 13 Biologie, Institute of Cell Biology, Center for Molecular Biology of Inflammation, 48149 Münster, Germany
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16
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Paraschiv A, Lagny TJ, Campos CV, Coudrier E, Bassereau P, Šarić A. Influence of membrane-cortex linkers on the extrusion of membrane tubes. Biophys J 2021; 120:598-606. [PMID: 33460596 PMCID: PMC7896025 DOI: 10.1016/j.bpj.2020.12.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/10/2020] [Accepted: 12/30/2020] [Indexed: 01/06/2023] Open
Abstract
The cell membrane is an inhomogeneous system composed of phospholipids, sterols, carbohydrates, and proteins that can be directly attached to underlying cytoskeleton. The protein linkers between the membrane and the cytoskeleton are believed to have a profound effect on the mechanical properties of the cell membrane and its ability to reshape. Here, we investigate the role of membrane-cortex linkers on the extrusion of membrane tubes using computer simulations and experiments. In simulations, we find that the force for tube extrusion has a nonlinear dependence on the density of membrane-cortex attachments: at a range of low and intermediate linker densities, the force is not significantly influenced by the presence of the membrane-cortex attachments and resembles that of the bare membrane. For large concentrations of linkers, however, the force substantially increases compared with the bare membrane. In both cases, the linkers provided membrane tubes with increased stability against coalescence. We then pulled tubes from HEK cells using optical tweezers for varying expression levels of the membrane-cortex attachment protein Ezrin. In line with simulations, we observed that overexpression of Ezrin led to an increased extrusion force, while Ezrin depletion had a negligible effect on the force. Our results shed light on the importance of local protein rearrangements for membrane reshaping at nanoscopic scales.
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Affiliation(s)
- Alexandru Paraschiv
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London, United Kingdom; MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Thibaut J Lagny
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France; Sorbonne Université, Paris, France; Institut Curie, PSL Research University CNRS UMR 144, Paris, France
| | - Christian Vanhille Campos
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London, United Kingdom; MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Evelyne Coudrier
- Institut Curie, PSL Research University CNRS UMR 144, Paris, France
| | - Patricia Bassereau
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France; Sorbonne Université, Paris, France
| | - Anđela Šarić
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London, United Kingdom; MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom.
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17
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Zhu M, Cornwall-Scoones J, Wang P, Handford CE, Na J, Thomson M, Zernicka-Goetz M. Developmental clock and mechanism of de novo polarization of the mouse embryo. Science 2021; 370:370/6522/eabd2703. [PMID: 33303584 DOI: 10.1126/science.abd2703] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/14/2020] [Indexed: 12/31/2022]
Abstract
Embryo polarization is critical for mouse development; however, neither the regulatory clock nor the molecular trigger that it activates is known. Here, we show that the embryo polarization clock reflects the onset of zygotic genome activation, and we identify three factors required to trigger polarization. Advancing the timing of transcription factor AP-2 gamma (Tfap2c) and TEA domain transcription factor 4 (Tead4) expression in the presence of activated Ras homolog family member A (RhoA) induces precocious polarization as well as subsequent cell fate specification and morphogenesis. Tfap2c and Tead4 induce expression of actin regulators that control the recruitment of apical proteins on the membrane, whereas RhoA regulates their lateral mobility, allowing the emergence of the apical domain. Thus, Tfap2c, Tead4, and RhoA are regulators for the onset of polarization and cell fate segregation in the mouse.
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Affiliation(s)
- Meng Zhu
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Jake Cornwall-Scoones
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech), Pasadena, CA 91125, USA
| | - Peizhe Wang
- Centre for Stem Cell Biology and Regenerative Medicine, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Charlotte E Handford
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.,Centre for Trophoblast Research, University of Cambridge, Cambridge CB2 3EG, UK
| | - Jie Na
- Centre for Stem Cell Biology and Regenerative Medicine, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Matt Thomson
- Division of Biology and Biological Engineering, California Institute of Technology (Caltech), Pasadena, CA 91125, USA
| | - Magdalena Zernicka-Goetz
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK. .,Division of Biology and Biological Engineering, California Institute of Technology (Caltech), Pasadena, CA 91125, USA.,Centre for Trophoblast Research, University of Cambridge, Cambridge CB2 3EG, UK
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18
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Welf ES, Miles CE, Huh J, Sapoznik E, Chi J, Driscoll MK, Isogai T, Noh J, Weems AD, Pohlkamp T, Dean K, Fiolka R, Mogilner A, Danuser G. Actin-Membrane Release Initiates Cell Protrusions. Dev Cell 2020; 55:723-736.e8. [PMID: 33308479 DOI: 10.1016/j.devcel.2020.11.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 09/08/2020] [Accepted: 11/20/2020] [Indexed: 01/04/2023]
Abstract
Despite the well-established role of actin polymerization as a driving mechanism for cell protrusion, upregulated actin polymerization alone does not initiate protrusions. Using a combination of theoretical modeling and quantitative live-cell imaging experiments, we show that local depletion of actin-membrane links is needed for protrusion initiation. Specifically, we show that the actin-membrane linker ezrin is depleted prior to protrusion onset and that perturbation of ezrin's affinity for actin modulates protrusion frequency and efficiency. We also show how actin-membrane release works in concert with actin polymerization, leading to a comprehensive model for actin-driven shape changes. Actin-membrane release plays a similar role in protrusions driven by intracellular pressure. Thus, our findings suggest that protrusion initiation might be governed by a universal regulatory mechanism, whereas the mechanism of force generation determines the shape and expansion properties of the protrusion.
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Affiliation(s)
- Erik S Welf
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Christopher E Miles
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA; Department of Biology, New York University, New York, NY 10012, USA
| | - Jaewon Huh
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Etai Sapoznik
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph Chi
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Meghan K Driscoll
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tadamoto Isogai
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jungsik Noh
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Andrew D Weems
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Theresa Pohlkamp
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kevin Dean
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Reto Fiolka
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA; Department of Biology, New York University, New York, NY 10012, USA.
| | - Gaudenz Danuser
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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19
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Ramalho JJ, Sepers JJ, Nicolle O, Schmidt R, Cravo J, Michaux G, Boxem M. C-terminal phosphorylation modulates ERM-1 localization and dynamics to control cortical actin organization and support lumen formation during Caenorhabditiselegans development. Development 2020; 147:dev188011. [PMID: 32586975 PMCID: PMC10755404 DOI: 10.1242/dev.188011] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/13/2020] [Indexed: 12/31/2023]
Abstract
ERM proteins are conserved regulators of cortical membrane specialization that function as membrane-actin linkers and molecular hubs. The activity of ERM proteins requires a conformational switch from an inactive cytoplasmic form into an active membrane- and actin-bound form, which is thought to be mediated by sequential PIP2 binding and phosphorylation of a conserved C-terminal threonine residue. Here, we use the single Caenorhabditiselegans ERM ortholog, ERM-1, to study the contribution of these regulatory events to ERM activity and tissue formation in vivo Using CRISPR/Cas9-generated erm-1 mutant alleles, we demonstrate that a PIP2-binding site is crucially required for ERM-1 function. By contrast, dynamic regulation of C-terminal T544 phosphorylation is not essential but modulates ERM-1 apical localization and dynamics in a tissue-specific manner, to control cortical actin organization and support lumen formation in epithelial tubes. Our work highlights the dynamic nature of ERM protein regulation during tissue morphogenesis and the importance of C-terminal phosphorylation in fine-tuning ERM activity in a tissue-specific context.
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Affiliation(s)
- João J Ramalho
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Jorian J Sepers
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Ophélie Nicolle
- Univ Rennes, CNRS, IGDR (Institut de Génétique et de Développement de Rennes), UMR 6290, F-35000 Rennes, France
| | - Ruben Schmidt
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Janine Cravo
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Grégoire Michaux
- Univ Rennes, CNRS, IGDR (Institut de Génétique et de Développement de Rennes), UMR 6290, F-35000 Rennes, France
| | - Mike Boxem
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
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20
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Bisaria A, Hayer A, Garbett D, Cohen D, Meyer T. Membrane-proximal F-actin restricts local membrane protrusions and directs cell migration. Science 2020; 368:1205-1210. [PMID: 32527825 DOI: 10.1126/science.aay7794] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 02/24/2020] [Accepted: 04/09/2020] [Indexed: 12/14/2022]
Abstract
Cell migration is driven by local membrane protrusion through directed polymerization of F-actin at the front. However, F-actin next to the plasma membrane also tethers the membrane and thus resists outgoing protrusions. Here, we developed a fluorescent reporter to monitor changes in the density of membrane-proximal F-actin (MPA) during membrane protrusion and cell migration. Unlike the total F-actin concentration, which was high in the front of migrating cells, MPA density was low in the front and high in the back. Back-to-front MPA density gradients were controlled by higher cofilin-mediated turnover of F-actin in the front. Furthermore, nascent membrane protrusions selectively extended outward from areas where MPA density was reduced. Thus, locally low MPA density directs local membrane protrusions and stabilizes cell polarization during cell migration.
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Affiliation(s)
- Anjali Bisaria
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
| | - Arnold Hayer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Damien Garbett
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Daniel Cohen
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Tobias Meyer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
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21
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Zhang X, Flores LR, Keeling MC, Sliogeryte K, Gavara N. Ezrin Phosphorylation at T567 Modulates Cell Migration, Mechanical Properties, and Cytoskeletal Organization. Int J Mol Sci 2020; 21:ijms21020435. [PMID: 31936668 PMCID: PMC7013973 DOI: 10.3390/ijms21020435] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 12/24/2019] [Accepted: 01/08/2020] [Indexed: 12/21/2022] Open
Abstract
Ezrin, a member of the ERM (ezrin/radixin/moesin) family of proteins, serves as a crosslinker between the plasma membrane and the actin cytoskeleton. By doing so, it provides structural links to strengthen the connection between the cell cortex and the plasma membrane, acting also as a signal transducer in multiple pathways during migration, proliferation, and endocytosis. In this study, we investigated the role of ezrin phosphorylation and its intracellular localization on cell motility, cytoskeleton organization, and cell stiffness, using fluorescence live-cell imaging, image quantification, and atomic force microscopy (AFM). Our results show that cells expressing constitutively active ezrin T567D (phosphomimetic) migrate faster and in a more directional manner, especially when ezrin accumulates at the cell rear. Similarly, image quantification results reveal that transfection with ezrin T567D alters the cell’s gross morphology and decreases cortical stiffness. In contrast, constitutively inactive ezrin T567A accumulates around the nucleus, and although it does not impair cell migration, it leads to a significant buildup of actin fibers, a decrease in nuclear volume, and an increase in cytoskeletal stiffness. Finally, cell transfection with the dominant negative ezrin FERM domain induces significant morphological and nuclear changes and affects actin, microtubules, and the intermediate filament vimentin, resulting in cytoskeletal fibers that are longer, thicker, and more aligned. Collectively, our results suggest that ezrin’s phosphorylation state and its intracellular localization plays a pivotal role in cell migration, modulating also biophysical properties, such as membrane–cortex linkage, cytoskeletal and nuclear organization, and the mechanical properties of cells.
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22
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Sonal, Ganzinger KA, Vogel SK, Mücksch J, Blumhardt P, Schwille P. Myosin-II activity generates a dynamic steady state with continuous actin turnover in a minimal actin cortex. J Cell Sci 2018; 132:jcs.219899. [PMID: 30538127 DOI: 10.1242/jcs.219899] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 10/16/2018] [Indexed: 01/24/2023] Open
Abstract
Dynamic reorganization of the actomyosin cytoskeleton allows fast modulation of the cell surface, which is vital for many cellular functions. Myosin-II motors generate the forces required for this remodeling by imparting contractility to actin networks. However, myosin-II activity might also have a more indirect contribution to cytoskeletal dynamics; it has been proposed that myosin activity increases actin turnover in various cellular contexts, presumably by enhancing disassembly. In vitro reconstitution of actomyosin networks has confirmed the role of myosin in actin network disassembly, but the reassembly of actin in these assays was limited by factors such as diffusional constraints and the use of stabilized actin filaments. Here, we present the reconstitution of a minimal dynamic actin cortex, where actin polymerization is catalyzed on the membrane in the presence of myosin-II activity. We demonstrate that myosin activity leads to disassembly and redistribution in this simplified cortex. Consequently, a new dynamic steady state emerges in which the actin network undergoes constant turnover. Our findings suggest a multifaceted role of myosin-II in the dynamics of the eukaryotic actin cortex. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Sonal
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | | | - Sven K Vogel
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Jonas Mücksch
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | | | - Petra Schwille
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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23
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Tsai FC, Bertin A, Bousquet H, Manzi J, Senju Y, Tsai MC, Picas L, Miserey-Lenkei S, Lappalainen P, Lemichez E, Coudrier E, Bassereau P. Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner. eLife 2018; 7:37262. [PMID: 30234483 PMCID: PMC6167055 DOI: 10.7554/elife.37262] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 09/14/2018] [Indexed: 01/12/2023] Open
Abstract
One challenge in cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat, positively or negatively curved. Using in vitro and cell biology approaches, we assess mechanisms of ezrin’s enrichment on curved membranes. We evidence that wild-type ezrin (ezrinWT) and its phosphomimetic mutant T567D (ezrinTD) do not deform membranes but self-assemble anti-parallelly, zipping adjacent membranes. EzrinTD’s specific conformation reduces intermolecular interactions, allows binding to actin filaments, which reduces membrane tethering, and promotes ezrin binding to positively-curved membranes. While neither ezrinTD nor ezrinWT senses negative curvature alone, we demonstrate that interacting with curvature-sensing I-BAR-domain proteins facilitates ezrin enrichment in negatively-curved membrane protrusions. Overall, our work demonstrates that ezrin can tether membranes, or be targeted to curved membranes, depending on conformations and interactions with actin and curvature-sensing binding partners.
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Affiliation(s)
- Feng-Ching Tsai
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Aurelie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Hugo Bousquet
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - John Manzi
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
| | - Yosuke Senju
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Meng-Chen Tsai
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.,Département de Microbiologie, Unité des Toxines Bactériennes, Université Paris Descartes, Institut Pasteur, Paris, France
| | - Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS UMR 9004, Montpellier, France
| | - Stephanie Miserey-Lenkei
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Pekka Lappalainen
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Emmanuel Lemichez
- Département de Microbiologie, Unité des Toxines Bactériennes, Université Paris Descartes, Institut Pasteur, Paris, France
| | - Evelyne Coudrier
- Sorbonne Université, Paris, France.,Compartimentation et dynamique cellulaire, Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - Patricia Bassereau
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, Paris, France.,Sorbonne Université, Paris, France
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Nöding H, Schön M, Reinermann C, Dörrer N, Kürschner A, Geil B, Mey I, Heussinger C, Janshoff A, Steinem C. Rheology of Membrane-Attached Minimal Actin Cortices. J Phys Chem B 2018; 122:4537-4545. [DOI: 10.1021/acs.jpcb.7b11491] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Helen Nöding
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Markus Schön
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Corinna Reinermann
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Nils Dörrer
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Aileen Kürschner
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Burkhard Geil
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Ingo Mey
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
| | - Claus Heussinger
- Institut für Theoretische Physik, Georg August Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Andreas Janshoff
- Institut für Physikalische Chemie, Georg August Universität Göttingen, Tammannstr. 6, 37077 Göttingen, Germany
| | - Claudia Steinem
- Institut für Organische und Biomolekulare Chemie, Georg August Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany
- Max-Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
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25
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Hinojosa LS, Holst M, Baarlink C, Grosse R. MRTF transcription and Ezrin-dependent plasma membrane blebbing are required for entotic invasion. J Cell Biol 2017; 216:3087-3095. [PMID: 28774893 PMCID: PMC5626544 DOI: 10.1083/jcb.201702010] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 06/06/2017] [Accepted: 07/12/2017] [Indexed: 12/20/2022] Open
Abstract
Entosis is a nonapoptotic form of cell death initiated by actomyosin-dependent homotypic cell-in-cell invasion that can be observed in malignant exudates during tumor progression. We previously demonstrated formin-mediated actin dynamics at the rear of the invading cell as well as nonapoptotic plasma membrane (PM) blebbing in this cellular motile process. Although the contractile actin cortex involved in bleb-driven motility is well characterized, a role for transcriptional regulation in this process has not been studied. Here, we explore the impact of the actin-controlled MRTF-SRF (myocardin-related transcription factor-serum response factor) pathway for sustained PM blebbing and entotic invasion. We find that cortical blebbing is tightly coupled to MRTF nuclear shuttling to promote the SRF transcriptional activity required for entosis. Furthermore, PM blebbing triggered SRF-mediated up-regulation of the metastasis-associated ERM protein Ezrin. Notably, Ezrin is sufficient and important to sustain bleb dynamics for cell-in-cell invasion when SRF is suppressed. Our results highlight the critical role of the actin-regulated MRTF transcriptional pathway for bleb-associated invasive motility, such as during entosis.
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Affiliation(s)
- Laura Soto Hinojosa
- Institute of Pharmacology, Biochemisch-Pharmakologisches Centrum Marburg, University of Marburg, Marburg, Germany.,Deutsche Forschungsgemeinschaft Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, University of Marburg, Marburg, Germany
| | - Manuel Holst
- Institute of Pharmacology, Biochemisch-Pharmakologisches Centrum Marburg, University of Marburg, Marburg, Germany
| | - Christian Baarlink
- Institute of Pharmacology, Biochemisch-Pharmakologisches Centrum Marburg, University of Marburg, Marburg, Germany
| | - Robert Grosse
- Institute of Pharmacology, Biochemisch-Pharmakologisches Centrum Marburg, University of Marburg, Marburg, Germany .,Deutsche Forschungsgemeinschaft Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, University of Marburg, Marburg, Germany
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26
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Clausen MP, Colin-York H, Schneider F, Eggeling C, Fritzsche M. Dissecting the actin cortex density and membrane-cortex distance in living cells by super-resolution microscopy. JOURNAL OF PHYSICS D: APPLIED PHYSICS 2017; 50:064002. [PMID: 28458398 PMCID: PMC5390943 DOI: 10.1088/1361-6463/aa52a1] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 11/30/2016] [Accepted: 12/08/2016] [Indexed: 05/30/2023]
Abstract
Nanoscale spacing between the plasma membrane and the underlying cortical actin cytoskeleton profoundly modulates cellular morphology, mechanics, and function. Measuring this distance has been a key challenge in cell biology. Current methods for dissecting the nanoscale spacing either limit themselves to complex survey design using fixed samples or rely on diffraction-limited fluorescence imaging whose spatial resolution is insufficient to quantify distances on the nanoscale. Using dual-color super-resolution STED (stimulated-emission-depletion) microscopy, we here overcome this challenge and accurately measure the density distribution of the cortical actin cytoskeleton and the distance between the actin cortex and the membrane in live Jurkat T-cells. We found an asymmetric cortical actin density distribution with a mean width of 230 (+105/-125) nm. The spatial distances measured between the maximum density peaks of the cortex and the membrane were bi-modally distributed with mean values of 50 ± 15 nm and 120 ± 40 nm, respectively. Taken together with the finite width of the cortex, our results suggest that in some regions the cortical actin is closer than 10 nm to the membrane and a maximum of 20 nm in others.
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Affiliation(s)
- M P Clausen
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, OX3 9DS Oxford, UK
- Department of Physics, Chemistry, and Pharmacy, MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - H Colin-York
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, OX3 9DS Oxford, UK
| | - F Schneider
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, OX3 9DS Oxford, UK
| | - C Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, OX3 9DS Oxford, UK
| | - M Fritzsche
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, OX3 9DS Oxford, UK
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford OX3 7LF Oxford, UK
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27
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Self-organizing actin patterns shape membrane architecture but not cell mechanics. Nat Commun 2017; 8:14347. [PMID: 28194011 PMCID: PMC5316839 DOI: 10.1038/ncomms14347] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 12/15/2016] [Indexed: 01/24/2023] Open
Abstract
Cell-free studies have demonstrated how collective action of actin-associated proteins can organize actin filaments into dynamic patterns, such as vortices, asters and stars. Using complementary microscopic techniques, we here show evidence of such self-organization of the actin cortex in living HeLa cells. During cell adhesion, an active multistage process naturally leads to pattern transitions from actin vortices over stars into asters. This process is primarily driven by Arp2/3 complex nucleation, but not by myosin motors, which is in contrast to what has been theoretically predicted and observed in vitro. Concomitant measurements of mechanics and plasma membrane fluidity demonstrate that changes in actin patterning alter membrane architecture but occur functionally independent of macroscopic cortex elasticity. Consequently, tuning the activity of the Arp2/3 complex to alter filament assembly may thus be a mechanism allowing cells to adjust their membrane architecture without affecting their macroscopic mechanical properties. In vitro models of actin organization show the formation of vortices, asters and stars. Here Fritzsche et al. show that such actin structures form in living cells in a manner dependent on the Arp2/3 complex but not myosin, and such structures influence membrane architecture but not cortex elasticity.
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28
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Cell Surface Mechanochemistry and the Determinants of Bleb Formation, Healing, and Travel Velocity. Biophys J 2016; 110:1636-1647. [PMID: 27074688 DOI: 10.1016/j.bpj.2016.03.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/07/2016] [Accepted: 03/07/2016] [Indexed: 11/21/2022] Open
Abstract
Blebs are pressure-driven cell protrusions implicated in cellular functions such as cell division, apoptosis, and cell motility, including motility of protease-inhibited cancer cells. Because of their mechanical nature, blebs inform us about general cell-surface mechanics, including membrane dynamics, pressure propagation throughout the cytoplasm, and the architecture and dynamics of the actin cortex. Mathematical models including detailed fluid dynamics have previously been used to understand bleb expansion. Here, we develop mathematical models in two and three dimensions on longer timescales that recapitulate the full bleb life cycle, including both expansion and healing by cortex reformation, in terms of experimentally accessible biophysical parameters such as myosin contractility, osmotic pressure, and turnover of actin and ezrin. The model provides conditions under which blebbing occurs, and naturally gives rise to traveling blebs. The model predicts conditions under which blebs travel or remain stationary, as well as the bleb traveling velocity, a quantity that has remained elusive in previous models. As previous studies have used blebs as reporters of membrane tension and pressure dynamics within the cell, we have used our system to investigate various pressure equilibration models and dynamic, nonuniform membrane tension to account for the shape of a traveling bleb. We also find that traveling blebs tend to expand in all directions unless otherwise constrained. One possible constraint could be provided by spatial heterogeneity in, for example, adhesion density.
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29
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Stanly TA, Fritzsche M, Banerji S, García E, Bernardino de la Serna J, Jackson DG, Eggeling C. Critical importance of appropriate fixation conditions for faithful imaging of receptor microclusters. Biol Open 2016; 5:1343-50. [PMID: 27464671 PMCID: PMC5051640 DOI: 10.1242/bio.019943] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Receptor clustering is known to trigger signalling events that contribute to critical changes in cellular functions. Faithful imaging of such clusters by means of fluorescence microscopy relies on the application of adequate cell fixation methods prior to immunolabelling in order to avoid artefactual redistribution by the antibodies themselves. Previous work has highlighted the inadequacy of fixation with paraformaldehyde (PFA) alone for efficient immobilisation of membrane-associated molecules, and the advantages of fixation with PFA in combination with glutaraldehyde (GA). Using fluorescence microscopy, we here highlight how inadequate fixation can lead to the formation of artefactual clustering of receptors in lymphatic endothelial cells, focussing on the transmembrane hyaluronan receptors LYVE-1 and CD44, and the homotypic adhesion molecule CD31, each of which displays their native diffuse surface distribution pattern only when visualised with the right fixation techniques, i.e. PFA/GA in combination. Fluorescence recovery after photobleaching (FRAP) confirms that the artefactual receptor clusters are indeed introduced by residual mobility. In contrast, we observed full immobilisation of membrane proteins in cells that were fixed and then subsequently permeabilised, irrespective of whether the fixative was PFA or PFA/GA in combination. Our study underlines the importance of choosing appropriate sample preparation protocols for preserving authentic receptor organisation in advanced fluorescence microscopy. Summary: Commonly used fixation protocols during immunolabelling can result in artefactual protein distribution. We highlight the artefacts in images and provide fixation conditions for studying membrane receptor organisation.
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Affiliation(s)
- Tess A Stanly
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Marco Fritzsche
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Suneale Banerji
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Esther García
- Wolfson Imaging Centre, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Jorge Bernardino de la Serna
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK Science & Technology Facilities Council, Rutherford Appleton Laboratory, Central Laser Facility, Research Complex at Harwell, Harwell-Oxford Campus, Oxford OX11 0FA, UK
| | - David G Jackson
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK Wolfson Imaging Centre, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
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30
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Eghiaian F, Rigato A, Scheuring S. Structural, mechanical, and dynamical variability of the actin cortex in living cells. Biophys J 2016; 108:1330-1340. [PMID: 25809247 DOI: 10.1016/j.bpj.2015.01.016] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/18/2014] [Accepted: 01/07/2015] [Indexed: 12/31/2022] Open
Abstract
In eukaryotic cells, an actin-based cortex lines the inner leaflet of the plasma membrane, endowing the cells with crucial mechanical and functional properties. Unfortunately, it has not been possible to study the structural dynamics of the actin cortex at high lateral resolution in living cells. Here, we performed atomic force microscopy time-lapse imaging and mechanical mapping of actin in the cortex of living cells at high lateral and temporal resolution. Cortical actin filaments adopted discernible arrangements, ranging from large parallel bundles with low connectivity to a tight meshwork of short filaments. Mixing of these architectures resulted in attuned cortex networks with specific connectivity, mechanical responses, and marked differences in their dynamic behavior.
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Affiliation(s)
- Frédéric Eghiaian
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Annafrancesca Rigato
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Simon Scheuring
- U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, Marseille, France.
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31
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Fritzsche M, Erlenkämper C, Moeendarbary E, Charras G, Kruse K. Actin kinetics shapes cortical network structure and mechanics. SCIENCE ADVANCES 2016; 2:e1501337. [PMID: 27152338 PMCID: PMC4846455 DOI: 10.1126/sciadv.1501337] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 03/30/2016] [Indexed: 05/20/2023]
Abstract
The actin cortex of animal cells is the main determinant of cellular mechanics. The continuous turnover of cortical actin filaments enables cells to quickly respond to stimuli. Recent work has shown that most of the cortical actin is generated by only two actin nucleators, the Arp2/3 complex and the formin Diaph1. However, our understanding of their interplay, their kinetics, and the length distribution of the filaments that they nucleate within living cells is poor. Such knowledge is necessary for a thorough comprehension of cellular processes and cell mechanics from basic polymer physics principles. We determined cortical assembly rates in living cells by using single-molecule fluorescence imaging in combination with stochastic simulations. We find that formin-nucleated filaments are, on average, 10 times longer than Arp2/3-nucleated filaments. Although formin-generated filaments represent less than 10% of all actin filaments, mechanical measurements indicate that they are important determinants of cortical elasticity. Tuning the activity of actin nucleators to alter filament length distribution may thus be a mechanism allowing cells to adjust their macroscopic mechanical properties to their physiological needs.
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Affiliation(s)
- Marco Fritzsche
- MRC Human Immunology Unit, Weatherall Institute for Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
- Corresponding author. E-mail: (M.F.); (K.K.); (G.C.)
| | - Christoph Erlenkämper
- Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany
- Institut Curie, 26 Rue d’Ulm, 75248 Paris Cedex 05, France
| | - Emad Moeendarbary
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Guillaume Charras
- London Centre for Nanotechnology, Institute for the Physics of Living Systems, and Department of Cell and Developmental Biology, University College London, London WC1H 0AH, UK
- Corresponding author. E-mail: (M.F.); (K.K.); (G.C.)
| | - Karsten Kruse
- Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany
- Corresponding author. E-mail: (M.F.); (K.K.); (G.C.)
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32
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Alterations of the cytoskeleton in human cells in space proved by life-cell imaging. Sci Rep 2016; 6:20043. [PMID: 26818711 PMCID: PMC4730242 DOI: 10.1038/srep20043] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 12/23/2015] [Indexed: 12/16/2022] Open
Abstract
Microgravity induces changes in the cytoskeleton. This might have an impact on cells and organs of humans in space. Unfortunately, studies of cytoskeletal changes in microgravity reported so far are obligatorily based on the analysis of fixed cells exposed to microgravity during a parabolic flight campaign (PFC). This study focuses on the development of a compact fluorescence microscope (FLUMIAS) for fast live-cell imaging under real microgravity. It demonstrates the application of the instrument for on-board analysis of cytoskeletal changes in FTC-133 cancer cells expressing the Lifeact-GFP marker protein for the visualization of F-actin during the 24th DLR PFC and TEXUS 52 rocket mission. Although vibration is an inevitable part of parabolic flight maneuvers, we successfully for the first time report life-cell cytoskeleton imaging during microgravity, and gene expression analysis after the 31st parabola showing a clear up-regulation of cytoskeletal genes. Notably, during the rocket flight the FLUMIAS microscope reveals significant alterations of the cytoskeleton related to microgravity. Our findings clearly demonstrate the applicability of the FLUMIAS microscope for life-cell imaging during microgravity, rendering it an important technological advance in live-cell imaging when dissecting protein localization.
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33
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Directional memory arises from long-lived cytoskeletal asymmetries in polarized chemotactic cells. Proc Natl Acad Sci U S A 2016; 113:1267-72. [PMID: 26764383 DOI: 10.1073/pnas.1513289113] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chemotaxis, the directional migration of cells in a chemical gradient, is robust to fluctuations associated with low chemical concentrations and dynamically changing gradients as well as high saturating chemical concentrations. Although a number of reports have identified cellular behavior consistent with a directional memory that could account for behavior in these complex environments, the quantitative and molecular details of such a memory process remain unknown. Using microfluidics to confine cellular motion to a 1D channel and control chemoattractant exposure, we observed directional memory in chemotactic neutrophil-like cells. We modeled this directional memory as a long-lived intracellular asymmetry that decays slower than observed membrane phospholipid signaling. Measurements of intracellular dynamics revealed that moesin at the cell rear is a long-lived element that when inhibited, results in a reduction of memory. Inhibition of ROCK (Rho-associated protein kinase), downstream of RhoA (Ras homolog gene family, member A), stabilized moesin and directional memory while depolymerization of microtubules (MTs) disoriented moesin deposition and also reduced directional memory. Our study reveals that long-lived polarized cytoskeletal structures, specifically moesin, actomyosin, and MTs, provide a directional memory in neutrophil-like cells even as they respond on short time scales to external chemical cues.
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34
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Ezrin is a Major Regulator of Membrane Tension in Epithelial Cells. Sci Rep 2015; 5:14700. [PMID: 26435322 PMCID: PMC4592969 DOI: 10.1038/srep14700] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 09/07/2015] [Indexed: 11/12/2022] Open
Abstract
Plasma membrane tension is responsible for a variety of cellular functions such as motility, cell division, and endocytosis. Since membrane tension is dominated by the attachment of the actin cortex to the inner leaflet of the plasma membrane, we investigated the importance of ezrin, a major cross-linker of the membrane-cytoskeleton interface, for cellular mechanics of confluent MDCK II cells. For this purpose, we carried out ezrin depletion experiments and also enhanced the number of active ezrin molecules at the interface. Mechanical properties were assessed by force indentation experiments followed by membrane tether extraction. PIP2 micelles were injected into individual living cells to reinforce the linkage between plasma membrane and actin-cortex, while weakening of this connection was reached by ezrin siRNA and administration of the inhibitors neomycin and NSC 668394, respectively. We observed substantial stiffening of cells and an increase in membrane tension after addition of PIP2 micelles. In contrast, reduction of active ezrin led to a decrease of membrane tension accompanied by loss of excess surface area, increase in cortical tension, remodelling of actin cytoskeleton, and reduction of cell height. The data confirm the importance of the ezrin-mediated connection between plasma membrane and cortex for cellular mechanics and cell morphology.
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35
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Andrade DM, Clausen MP, Keller J, Mueller V, Wu C, Bear JE, Hell SW, Lagerholm BC, Eggeling C. Cortical actin networks induce spatio-temporal confinement of phospholipids in the plasma membrane--a minimally invasive investigation by STED-FCS. Sci Rep 2015; 5:11454. [PMID: 26118385 PMCID: PMC4484492 DOI: 10.1038/srep11454] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 05/20/2015] [Indexed: 11/09/2022] Open
Abstract
Important discoveries in the last decades have changed our view of the plasma membrane organisation. Specifically, the cortical cytoskeleton has emerged as a key modulator of the lateral diffusion of membrane proteins. Cytoskeleton-dependent compartmentalised lipid diffusion has been proposed, but this concept remains controversial because this phenomenon has thus far only been observed with artefact-prone probes in combination with a single technique: single particle tracking. In this paper, we report the first direct observation of compartmentalised phospholipid diffusion in the plasma membrane of living cells using a minimally invasive, fluorescent dye labelled lipid analogue. These observations were made using optical STED nanoscopy in combination with fluorescence correlation spectroscopy (STED-FCS), a technique which allows the study of membrane dynamics on a sub-millisecond time-scale and with a spatial resolution of down to 40 nm. Specifically, we find that compartmentalised phospholipid diffusion depends on the cortical actin cytoskeleton, and that this constrained diffusion is directly dependent on the F-actin branching nucleator Arp2/3. These findings provide solid evidence that the Arp2/3-dependent cortical actin cytoskeleton plays a pivotal role in the dynamic organisation of the plasma membrane, potentially regulating fundamental cellular processes.
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Affiliation(s)
- Débora M Andrade
- 1] Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany [2] Centre for Neural Circuits and Behaviour, University of Oxford, Mansfield Road, Oxford OX1 3SR, UK
| | - Mathias P Clausen
- 1] Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany [2] MRC Human Immunology Unit and Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK [3] MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, Odense M,DK-5230, Denmark
| | - Jan Keller
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
| | - Veronika Mueller
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
| | - Congying Wu
- Department of Cell &Developmental Biology, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill NC 27599, USA
| | - James E Bear
- 1] Department of Cell &Developmental Biology, and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill NC 27599, USA [2] Howard Hughes Medical Institute, University of North Carolina, Chapel Hill NC 27599, USA
| | - Stefan W Hell
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany
| | - B Christoffer Lagerholm
- 1] MRC Human Immunology Unit and Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK [2] MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, Campusvej 55, Odense M,DK-5230, Denmark
| | - Christian Eggeling
- 1] Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen 37077, Germany [2] MRC Human Immunology Unit and Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
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36
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The NHERF2 sequence adjacent and upstream of the ERM-binding domain affects NHERF2-ezrin binding and dexamethasone stimulated NHE3 activity. Biochem J 2015; 470:77-90. [PMID: 26251448 PMCID: PMC4613507 DOI: 10.1042/bj20150238] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 06/16/2015] [Indexed: 12/19/2022]
Abstract
The microvillar localization of Na+-H+ exchanger regulatory factor (NHERF)1/2 requires not only ezrin, radixin and moesin (ERM)-binding domain (EBD) but also a newly defined ERM-binding regulatory sequence (EBRS) that modulates NHERF1/2–ezrin binding. NHERF2 EBRS is also regulated by phosphorylation, which affects NHE3 (Na+-H+ exchanger 3) stimulation by dexamethasone. In the brush border of intestinal and kidney epithelial cells, scaffolding proteins ezrin, Na+-H+ exchanger regulatory factor (NHERF)1 and NHERF2 play important roles in linking transmembrane proteins to the cytoskeleton and assembling signalling regulatory complexes. The last 30 carboxyl residues of NHERF1 and NHERF2 form the EBDs [ezrin, radixin and moesin (ERM)-binding domain]. The current study found that NHERF1/2 contain an ERM-binding regulatory sequence (EBRS), which facilitates the interaction between the EBD and ezrin. The EBRSs are located within 24 and 19 residues immediately upstream of EBDs for NHERF1 and NHERF2 respectively. In OK (opossum kidney) epithelial cells, EBRSs are necessary along with the EBD to distribute NHERF1 and NHERF2 exclusively to the apical domain. Furthermore, phosphorylation of Ser303 located in the EBRS of NHERF2, decreases the binding affinity for ezrin, dislocates apical NHERF2 into the cytosol and increases the NHERF2 microvillar mobility rate. Moreover, increased phosphorylation of Ser303 was functionally significant preventing acute stimulation of NHE3 (Na+-H+ exchanger 3) activity by dexamethasone.
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Dissecting protein reaction dynamics in living cells by fluorescence recovery after photobleaching. Nat Protoc 2015; 10:660-80. [DOI: 10.1038/nprot.2015.042] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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