1
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Beta C, Edelstein-Keshet L, Gov N, Yochelis A. From actin waves to mechanism and back: How theory aids biological understanding. eLife 2023; 12:e87181. [PMID: 37428017 DOI: 10.7554/elife.87181] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/01/2023] [Indexed: 07/11/2023] Open
Abstract
Actin dynamics in cell motility, division, and phagocytosis is regulated by complex factors with multiple feedback loops, often leading to emergent dynamic patterns in the form of propagating waves of actin polymerization activity that are poorly understood. Many in the actin wave community have attempted to discern the underlying mechanisms using experiments and/or mathematical models and theory. Here, we survey methods and hypotheses for actin waves based on signaling networks, mechano-chemical effects, and transport characteristics, with examples drawn from Dictyostelium discoideum, human neutrophils, Caenorhabditis elegans, and Xenopus laevis oocytes. While experimentalists focus on the details of molecular components, theorists pose a central question of universality: Are there generic, model-independent, underlying principles, or just boundless cell-specific details? We argue that mathematical methods are equally important for understanding the emergence, evolution, and persistence of actin waves and conclude with a few challenges for future studies.
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Affiliation(s)
- Carsten Beta
- Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany
| | | | - Nir Gov
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Arik Yochelis
- Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
- Department of Physics, Ben-Gurion University of the Negev, Be'er Sheva, Israel
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2
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Heckman CA, Ademuyiwa OM, Cayer ML. How filopodia respond to calcium in the absence of a calcium-binding structural protein: non-channel functions of TRP. Cell Commun Signal 2022; 20:130. [PMID: 36028898 PMCID: PMC9414478 DOI: 10.1186/s12964-022-00927-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 06/21/2022] [Indexed: 11/18/2022] Open
Abstract
Background For many cell types, directional locomotion depends on their maintaining filopodia at the leading edge. Filopodia lack any Ca2+-binding structural protein but respond to store-operated Ca2+ entry (SOCE). Methods SOCE was induced by first replacing the medium with Ca2+-free salt solution with cyclopiazonic acid (CPA). This lowers Ca2+ in the ER and causes stromal interacting molecule (STIM) to be translocated to the cell surface. After this priming step, CPA was washed out, and Ca2+ influx restored by addition of extracellular Ca2+. Intracellular Ca2+ levels were measured by calcium orange fluorescence. Regulatory mechanisms were identified by pharmacological treatments. Proteins mediating SOCE were localized by immunofluorescence and analyzed after image processing. Results Depletion of the ER Ca2+ increased filopodia prevalence briefly, followed by a spontaneous decline that was blocked by inhibitors of endocytosis. Intracellular Ca2+ increased continuously for ~ 50 min. STIM and a transient receptor potential canonical (TRPC) protein were found in separate compartments, but an aquaporin unrelated to SOCE was present in both. STIM1- and TRPC1-bearing vesicles were trafficked on microtubules. During depletion, STIM1 migrated to the surface where it coincided with Orai in punctae, as expected. TRPC1 was partially colocalized with Vamp2, a rapidly releasable pool marker, and with phospholipases (PLCs). TRPC1 retreated to internal compartments during ER depletion. Replenishment of extracellular Ca2+ altered the STIM1 distribution, which came to resemble that of untreated cells. Vamp2 and TRPC1 underwent exocytosis and became homogeneously distributed on the cell surface. This was accompanied by an increased prevalence of filopodia, which was blocked by inhibitors of TRPC1/4/5 and endocytosis. Conclusions Because the media were devoid of ligands that activate receptors during depletion and Ca2+ replenishment, we could attribute filopodia extension to SOCE. We propose that the Orai current stimulates exocytosis of TRPC-bearing vesicles, and that Ca2+ influx through TRPC inhibits PLC activity. This allows regeneration of the substrate, phosphatidylinositol 4,5 bisphosphate (PIP2), a platform for assembling proteins, e. g. Enabled and IRSp53. TRPC contact with PLC is required but is broken by TRPC dissemination. This explains how STIM1 regulates the cell’s ability to orient itself in response to attractive or repulsive cues. Video Abstract
Supplementary Information The online version contains supplementary material available at 10.1186/s12964-022-00927-y.
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Affiliation(s)
- C A Heckman
- Department of Biological Sciences, 217 Life Science Building, Bowling Green State University, Bowling Green, OH, 43403-0001, USA.
| | - O M Ademuyiwa
- Department of Biological Sciences, 217 Life Science Building, Bowling Green State University, Bowling Green, OH, 43403-0001, USA
| | - M L Cayer
- Center for Microscopy and Microanalysis, Bowling Green State University, Bowling Green, OH, 43403, USA
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3
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Platzl C, Kaser-Eichberger A, Benavente-Perez A, Schroedl F. The choroid-sclera interface: An ultrastructural study. Heliyon 2022; 8:e09408. [PMID: 35586330 PMCID: PMC9108890 DOI: 10.1016/j.heliyon.2022.e09408] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/29/2021] [Accepted: 05/05/2022] [Indexed: 11/27/2022] Open
Abstract
Emmetropization is an active and visually guided process that involves the retina, choroid and sclera, and results in compensatory changes in eye growth. This guided growth is the result of visual cues and possibly mechanical interactions being translated into growth signals via molecular events from the retina into the choroid and sclera, through the choroidal scleral transition zone. If mechanical interactions were a part of the choroid-sclera signaling transduction cascade, specific morphological arrangements should be detectable in this region at the ultrastructural level. The goal of this study was to investigate the ultrastructural features of the choroidal scleral transition zone by comparing avian, non-human primate and human eyes, with the goal to confirm whether specific mechanical structures are present. Choroidal and scleral tissue from chicken, marmoset, and human eyes were imaged using transmission electron microscopy to document the choroid-sclera transition zone. In chicken eyes, fibroblast lamellae bordered the scleral matrix and formed thin end elongated processes that were undercut by scleral collagen fibrils. These processes back-looped into the scleral matrix, and displayed small club-like membrane protrusions. Differences in these arrangements in mature vs young chickens were not detected. The club-like membrane protrusions identified in chickens were rare in marmoset eyes, which instead exhibited two types of collagen fibrils discriminated by size, and were absent in the human eyes investigated. In marmoset and human eyes, elastic components were detected in the transition zone that were absent in chickens. In summary, cellular/membrane specializations indicating a mechanical interaction at the choroid-sclera transition zone were not detected in chicken, non-human primate or human eyes. If mechanotransduction is necessary for scleral growth, matrix integrity or development, alternative structural arrangements might be required.
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Affiliation(s)
- C. Platzl
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology -Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - A. Kaser-Eichberger
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology -Salzburg, Paracelsus Medical University, Salzburg, Austria
| | | | - F. Schroedl
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology -Salzburg, Paracelsus Medical University, Salzburg, Austria
- Corresponding author.
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4
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Tracking of Endothelial Cell Migration and Stiffness Measurements Reveal the Role of Cytoskeletal Dynamics. Int J Mol Sci 2022; 23:ijms23010568. [PMID: 35008993 PMCID: PMC8745078 DOI: 10.3390/ijms23010568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/23/2021] [Accepted: 12/30/2021] [Indexed: 02/01/2023] Open
Abstract
Cell migration is a complex, tightly regulated multistep process in which cytoskeletal reorganization and focal adhesion redistribution play a central role. Core to both individual and collective migration is the persistent random walk, which is characterized by random force generation and resistance to directional change. We first discuss a model that describes the stochastic movement of ECs and characterizes EC persistence in wound healing. To that end, we pharmacologically disrupted cytoskeletal dynamics, cytochalasin D for actin and nocodazole for tubulin, to understand its contributions to cell morphology, stiffness, and motility. As such, the use of Atomic Force Microscopy (AFM) enabled us to probe the topography and stiffness of ECs, while time lapse microscopy provided observations in wound healing models. Our results suggest that actin and tubulin dynamics contribute to EC shape, compressive moduli, and directional organization in collective migration. Insights from the model and time lapse experiment suggest that EC speed and persistence are directionally organized in wound healing. Pharmacological disruptions suggest that actin and tubulin dynamics play a role in collective migration. Current insights from both the model and experiment represent an important step in understanding the biomechanics of EC migration as a therapeutic target.
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5
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Zhou F, Schaffer SA, Schreiber C, Segerer FJ, Goychuk A, Frey E, Rädler JO. Quasi-periodic migration of single cells on short microlanes. PLoS One 2020; 15:e0230679. [PMID: 32282802 PMCID: PMC7153896 DOI: 10.1371/journal.pone.0230679] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 03/05/2020] [Indexed: 12/02/2022] Open
Abstract
Cell migration on microlanes represents a suitable and simple platform for the exploration of the molecular mechanisms underlying cell cytoskeleton dynamics. Here, we report on the quasi-periodic movement of cells confined in stripe-shaped microlanes. We observe persistent polarized cell shapes and directed pole-to-pole motion within the microlanes. Cells depolarize at one end of a given microlane, followed by delayed repolarization towards the opposite end. We analyze cell motility via the spatial velocity distribution, the velocity frequency spectrum and the reversal time as a measure for depolarization and spontaneous repolarization of cells at the microlane ends. The frequent encounters of a boundary in the stripe geometry provides a robust framework for quantitative investigations of the cytoskeleton protrusion and repolarization dynamics. In a first advance to rigorously test physical models of cell migration, we find that the statistics of the cell migration is recapitulated by a Cellular Potts model with a minimal description of cytoskeleton dynamics. Using LifeAct-GFP transfected cells and microlanes with differently shaped ends, we show that the local deformation of the leading cell edge in response to the tip geometry can locally either amplify or quench actin polymerization, while leaving the average reversal times unaffected.
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Affiliation(s)
- Fang Zhou
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Sophia A. Schaffer
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christoph Schreiber
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Felix J. Segerer
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andriy Goychuk
- Arnold-Sommerfeld-Center for Theoretical Physics, Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Erwin Frey
- Arnold-Sommerfeld-Center for Theoretical Physics, Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Joachim O. Rädler
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
- * E-mail:
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6
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Illukkumbura R, Bland T, Goehring NW. Patterning and polarization of cells by intracellular flows. Curr Opin Cell Biol 2019; 62:123-134. [PMID: 31760155 PMCID: PMC6968950 DOI: 10.1016/j.ceb.2019.10.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/11/2019] [Accepted: 10/16/2019] [Indexed: 11/19/2022]
Abstract
Beginning with Turing’s seminal work [1], decades of research have demonstrated the fundamental ability of biochemical networks to generate and sustain the formation of patterns. However, it is increasingly appreciated that biochemical networks both shape and are shaped by physical and mechanical processes [2, 3, 4]. One such process is fluid flow. In many respects, the cytoplasm, membrane and actin cortex all function as fluids, and as they flow, they drive bulk transport of molecules throughout the cell. By coupling biochemical activity to long range molecular transport, flows can shape the distributions of molecules in space. Here we review the various types of flows that exist in cells, with the aim of highlighting recent advances in our understanding of how flows are generated and how they contribute to intracellular patterning processes, such as the establishment of cell polarity.
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Affiliation(s)
| | - Tom Bland
- The Francis Crick Institute, London, UK; Institute for the Physics of Living Systems, University College London, London, UK
| | - Nathan W Goehring
- The Francis Crick Institute, London, UK; Institute for the Physics of Living Systems, University College London, London, UK; MRC Laboratory for Molecular Cell Biology, University College London, London, UK.
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7
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Wang C, Choi HJ, Kim SJ, Desai A, Lee N, Kim D, Bae Y, Lee K. Deconvolution of subcellular protrusion heterogeneity and the underlying actin regulator dynamics from live cell imaging. Nat Commun 2018; 9:1688. [PMID: 29703977 PMCID: PMC5923236 DOI: 10.1038/s41467-018-04030-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 03/29/2018] [Indexed: 12/25/2022] Open
Abstract
Cell protrusion is morphodynamically heterogeneous at the subcellular level. However, the mechanism of cell protrusion has been understood based on the ensemble average of actin regulator dynamics. Here, we establish a computational framework called HACKS (deconvolution of heterogeneous activity in coordination of cytoskeleton at the subcellular level) to deconvolve the subcellular heterogeneity of lamellipodial protrusion from live cell imaging. HACKS identifies distinct subcellular protrusion phenotypes based on machine-learning algorithms and reveals their underlying actin regulator dynamics at the leading edge. Using our method, we discover "accelerating protrusion", which is driven by the temporally ordered coordination of Arp2/3 and VASP activities. We validate our finding by pharmacological perturbations and further identify the fine regulation of Arp2/3 and VASP recruitment associated with accelerating protrusion. Our study suggests HACKS can identify specific subcellular protrusion phenotypes susceptible to pharmacological perturbation and reveal how actin regulator dynamics are changed by the perturbation.
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Affiliation(s)
- Chuangqi Wang
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, 01609, USA
| | - Hee June Choi
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, 01609, USA
| | - Sung-Jin Kim
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, 01609, USA
| | - Aesha Desai
- Department of Pathology and Anatomical Sciences, Computational Cell Biology, Anatomy and Pathology Program, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, 14203, USA
| | - Namgyu Lee
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Dohoon Kim
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Yongho Bae
- Department of Pathology and Anatomical Sciences, Computational Cell Biology, Anatomy and Pathology Program, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, 14203, USA
| | - Kwonmoo Lee
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, 01609, USA.
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8
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Toledo-Leyva A, Villegas-Pineda JC, Encarnación-Guevara S, Gallardo-Rincón D, Talamás-Rohana P. Effect of ovarian cancer ascites on SKOV-3 cells proteome: new proteins associated with aggressive phenotype in epithelial ovarian cancer. Proteome Sci 2018; 16:3. [PMID: 29456457 PMCID: PMC5810116 DOI: 10.1186/s12953-018-0133-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 02/06/2018] [Indexed: 12/27/2022] Open
Abstract
Background Epithelial ovarian cancer is the second most lethal gynecological cancer worldwide. Ascites can be found in all clinical stages, however in advanced disease stages IIIC and IV it is more frequent and could be massive, associated with worse prognosis. Due to the above, it was our interest to understanding how the ascites of ovarian cancer patients induces the mechanisms by which the cells present in it acquire a more aggressive phenotype and to know new proteins associated to this process. Methods A proteomic analysis of SKOV-3 cells treated with five different EOC ascites was performed by two-dimensional electrophoresis coupled to MALDI-TOF. The level of expression of the proteins of interest was validated by RT-PCR because several of these proteins have only been reported at the messenger level. Results Among the proteins identified that increased their expression in ascites-treated SKOV-3 cells, were Ran GTPase, ZNF268, and Synaptotagmin like-3. On the other hand, proteins that were negatively regulated by ascites were HLA-I, HSPB1, ARF1, Synaptotagmin 1, and hnRNPH1, among others. Furthermore, an interactome for every one of these proteins was done in order to identify biological processes, molecular actions, and cellular components in which they may participate. Conclusions Identified proteins participate in cellular processes highly relevant to the aggressive phenotype such as nuclear transport, regulation of gene expression, vesicular trafficking, evasion of the immune response, invasion, metastasis, and in resistance to chemotherapy. These proteins may represent a source of information which has the potential to be evaluated for the design of therapies directed against these malignant cells that reside on ovarian cancer ascites.
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Affiliation(s)
- Alfredo Toledo-Leyva
- 1Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, Delegación Gustavo A. Madero, 07360 Ciudad de México, Mexico.,Present address: Centro de Investigación de Cáncer en Sonora, Ciudad Obregón, Sonora 85010 Mexico
| | - Julio César Villegas-Pineda
- 1Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, Delegación Gustavo A. Madero, 07360 Ciudad de México, Mexico.,Present address: Centro de Investigación de Cáncer en Sonora, Ciudad Obregón, Sonora 85010 Mexico
| | - Sergio Encarnación-Guevara
- 2Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n Col. Chamilpa, 62210 Cuernavaca, Morelos Mexico
| | - Dolores Gallardo-Rincón
- 3Instituto Nacional de Cancerología, Av. San Fernando No. 22, Col. Sección XVI Delegación Tlalpan, 14080 Ciudad de México, Mexico
| | - Patricia Talamás-Rohana
- 1Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, Delegación Gustavo A. Madero, 07360 Ciudad de México, Mexico
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9
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Ryan GL, Holz D, Yamashiro S, Taniguchi D, Watanabe N, Vavylonis D. Cell protrusion and retraction driven by fluctuations in actin polymerization: A two-dimensional model. Cytoskeleton (Hoboken) 2017; 74:490-503. [PMID: 28752950 PMCID: PMC5725282 DOI: 10.1002/cm.21389] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/19/2017] [Accepted: 07/24/2017] [Indexed: 12/23/2022]
Abstract
Animal cells that spread onto a surface often rely on actin-rich lamellipodial extensions to execute protrusion. Many cell types recently adhered on a two-dimensional substrate exhibit protrusion and retraction of their lamellipodia, even though the cell is not translating. Travelling waves of protrusion have also been observed, similar to those observed in crawling cells. These regular patterns of protrusion and retraction allow quantitative analysis for comparison to mathematical models. The periodic fluctuations in leading edge position of XTC cells have been linked to excitable actin dynamics using a one-dimensional model of actin dynamics, as a function of arc-length along the cell. In this work we extend this earlier model of actin dynamics into two dimensions (along the arc-length and radial directions of the cell) and include a model membrane that protrudes and retracts in response to the changing number of free barbed ends of actin filaments near the membrane. We show that if the polymerization rate at the barbed ends changes in response to changes in their local concentration at the leading edge and/or the opposing force from the cell membrane, the model can reproduce the patterns of membrane protrusion and retraction seen in experiment. We investigate both Brownian ratchet and switch-like force-velocity relationships between the membrane load forces and actin polymerization rate. The switch-like polymerization dynamics recover the observed patterns of protrusion and retraction as well as the fluctuations in F-actin concentration profiles. The model generates predictions for the behavior of cells after local membrane tension perturbations.
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Affiliation(s)
- Gillian L. Ryan
- Department of Physics, Kettering University, 1700 University Avenue, Flint MI 48504, United States
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem PA 18105, United States
| | - Danielle Holz
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem PA 18105, United States
| | - Sawako Yamashiro
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Daisuke Taniguchi
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Naoki Watanabe
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Dimitrios Vavylonis
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem PA 18105, United States
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10
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Nickaeen M, Novak IL, Pulford S, Rumack A, Brandon J, Slepchenko BM, Mogilner A. A free-boundary model of a motile cell explains turning behavior. PLoS Comput Biol 2017; 13:e1005862. [PMID: 29136638 PMCID: PMC5705165 DOI: 10.1371/journal.pcbi.1005862] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 11/28/2017] [Accepted: 10/31/2017] [Indexed: 01/14/2023] Open
Abstract
To understand shapes and movements of cells undergoing lamellipodial motility, we systematically explore minimal free-boundary models of actin-myosin contractility consisting of the force-balance and myosin transport equations. The models account for isotropic contraction proportional to myosin density, viscous stresses in the actin network, and constant-strength viscous-like adhesion. The contraction generates a spatially graded centripetal actin flow, which in turn reinforces the contraction via myosin redistribution and causes retraction of the lamellipodial boundary. Actin protrusion at the boundary counters the retraction, and the balance of the protrusion and retraction shapes the lamellipodium. The model analysis shows that initiation of motility critically depends on three dimensionless parameter combinations, which represent myosin-dependent contractility, a characteristic viscosity-adhesion length, and a rate of actin protrusion. When the contractility is sufficiently strong, cells break symmetry and move steadily along either straight or circular trajectories, and the motile behavior is sensitive to conditions at the cell boundary. Scanning of a model parameter space shows that the contractile mechanism of motility supports robust cell turning in conditions where short viscosity-adhesion lengths and fast protrusion cause an accumulation of myosin in a small region at the cell rear, destabilizing the axial symmetry of a moving cell. To understand shapes and movements of simple motile cells, we systematically explore minimal models describing a cell as a two-dimensional actin-myosin gel with a free boundary. The models account for actin-myosin contraction balanced by viscous stresses in the actin gel and uniform adhesion. The myosin contraction causes the lamellipodial boundary to retract. Actin protrusion at the boundary counters the retraction, and the balance of protrusion and retraction shapes the cell. The models reproduce a variety of motile shapes observed experimentally. The analysis shows that the mechanical state of a cell depends on a small number of parameters. We find that when the contractility is sufficiently strong, cells break symmetry and move steadily along either straight or circular trajectory. Scanning model parameters shows that the contractile mechanism of motility supports robust cell turning behavior in conditions where deformable actin gel and fast protrusion destabilize the axial symmetry of a moving cell.
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Affiliation(s)
- Masoud Nickaeen
- Richard D. Berlin Center for Cell Analysis and Modeling, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, United States of America
| | - Igor L. Novak
- Richard D. Berlin Center for Cell Analysis and Modeling, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, United States of America
| | - Stephanie Pulford
- Center for Engineering Learning & Teaching, University of Washington, Seattle, WA, United States of America
| | - Aaron Rumack
- Department of Computer Science, Cornell University, Ithaca, NY, United States of America
| | - Jamie Brandon
- Department of Mathematics, Adrian College, Adrian, MI, United States of America
| | - Boris M. Slepchenko
- Richard D. Berlin Center for Cell Analysis and Modeling, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, United States of America
| | - Alex Mogilner
- Courant Institute and Department of Biology, New York University, New York, NY, United States of America
- * E-mail:
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11
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Maninova M, Caslavsky J, Vomastek T. The assembly and function of perinuclear actin cap in migrating cells. PROTOPLASMA 2017; 254:1207-1218. [PMID: 28101692 DOI: 10.1007/s00709-017-1077-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/09/2017] [Indexed: 05/24/2023]
Abstract
Stress fibers are actin bundles encompassing actin filaments, actin-crosslinking, and actin-associated proteins that represent the major contractile system in the cell. Different types of stress fibers assemble in adherent cells, and they are central to diverse cellular processes including establishment of the cell shape, morphogenesis, cell polarization, and migration. Stress fibers display specific cellular organization and localization, with ventral fibers present at the basal side, and dorsal fibers and transverse actin arcs rising at the cell front from the ventral to the dorsal side and toward the nucleus. Perinuclear actin cap fibers are a specific subtype of stress fibers that rise from the leading edge above the nucleus and terminate at the cell rear forming a dome-like structure. Perinuclear actin cap fibers are fixed at three points: both ends are anchored in focal adhesions, while the central part is physically attached to the nucleus and nuclear lamina through the linker of nucleoskeleton and cytoskeleton (LINC) complex. Here, we discuss recent work that provides new insights into the mechanism of assembly and the function of these actin stress fibers that directly link extracellular matrix and focal adhesions with the nuclear envelope.
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Affiliation(s)
- Miloslava Maninova
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic
| | - Josef Caslavsky
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic
| | - Tomas Vomastek
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic.
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Ávila-Rodríguez D, Solano Agama C, González-Pozos S, Vicente Méndez-Méndez J, Ortiz Plata A, Arreola-Mendoza L, Mendoza-Garrido ME. The shift in GH3 cell shape and cell motility is dependent on MLCK and ROCK. Exp Cell Res 2017; 354:1-17. [PMID: 28300565 DOI: 10.1016/j.yexcr.2017.03.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/02/2017] [Accepted: 03/09/2017] [Indexed: 11/24/2022]
Abstract
Cytoskeletal organization, actin-myosin contractility and the cell membrane together regulate cell morphology in response to the cell environment, wherein the extracellular matrix (ECM) is an indispensable component. Plasticity in cell shape enables cells to adapt their migration mode to their surroundings. GH3 endocrine cells respond to different ECM proteins, acquiring different morphologies: a rounded on collagen I-III (C I-III) and an elongated on collagen IV (C IV). However, the identities of the molecules that participate in these responses remain unknown. Considering that actin-myosin contractility is crucial to maintaining cell shape, we analyzed the participation of MLCK and ROCK in the acquisition of cell shape, the generation of cellular tension and the cell motility mode. We found that a rounded shape with high cortical tension depends on MLCK and ROCK, whereas in cells with an elongated shape, MLCK is the primary protein responsible for cell spreading. Further, in cells with a slow and directionally persistent motility, MLCK predominates, while rapid and erratic movement is ROCK-dependent. This behavior also correlates with GTPase activation. Cells on C I-III exhibited higher Rho-GTPase activity than cells on C IV and vice versa with Rac-GTPase activity, showing a plastic response of GH3 cells to their environment, leading to the generation of different cytoskeleton and membrane organizations and resulting in two movement strategies, rounded and fibroblastoid-like.
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Affiliation(s)
- Dulce Ávila-Rodríguez
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico
| | - Carmen Solano Agama
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico
| | - Sirenia González-Pozos
- Central Laboratories, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico
| | - Juan Vicente Méndez-Méndez
- Center of Nanosciences and Micro and Nanotechnology (CNMN), National Polytechnic Institute, Mexico City, Mexico
| | - Alma Ortiz Plata
- Laboratory of Experimental Neuropathology, National Institute of Neurology and Neurosurgery, Manuel Velasco Suarez, Mexico City, Mexico
| | - Laura Arreola-Mendoza
- Department of Biosciences and Engineering, Center for Interdisciplinary Research and Studies on Environment and Development (CIIEMAD), National Polytechnic Institute, Mexico City, Mexico
| | - María E Mendoza-Garrido
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Mexico City, Mexico.
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13
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Klímová Z, Bráborec V, Maninová M, Čáslavský J, Weber MJ, Vomastek T. Symmetry breaking in spreading RAT2 fibroblasts requires the MAPK/ERK pathway scaffold RACK1 that integrates FAK, p190A-RhoGAP and ERK2 signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2189-200. [PMID: 27212270 DOI: 10.1016/j.bbamcr.2016.05.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 04/22/2016] [Accepted: 05/17/2016] [Indexed: 11/28/2022]
Abstract
The spreading of adhering cells is a morphogenetic process during which cells break spherical or radial symmetry and adopt migratory polarity with spatially segregated protruding cell front and non-protruding cell rear. The organization and regulation of these symmetry-breaking events, which are both complex and stochastic, are not fully understood. Here we show that in radially spreading cells, symmetry breaking commences with the development of discrete non-protruding regions characterized by large but sparse focal adhesions and long peripheral actin bundles. Establishment of this non-protruding static region specifies the distally oriented protruding cell front and thus determines the polarity axis and the direction of cell migration. The development of non-protruding regions requires ERK2 and the ERK pathway scaffold protein RACK1. RACK1 promotes adhesion-mediated activation of ERK2 that in turn inhibits p190A-RhoGAP signaling by reducing the peripheral localization of p190A-RhoGAP. We propose that sustained ERK signaling at the prospective cell rear induces p190A-RhoGAP depletion from the cell periphery resulting in peripheral actin bundles and cell rear formation. Since cell adhesion activates both ERK and p190A-RhoGAP signaling this constitutes a spatially confined incoherent feed-forward signaling circuit.
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Affiliation(s)
| | | | | | | | - Michael J Weber
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Tomáš Vomastek
- Institute of Microbiology AS CR, Prague, Czech Republic.
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14
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Cortical actin and the plasma membrane: inextricably intertwined. Curr Opin Cell Biol 2016; 38:81-9. [PMID: 26986983 DOI: 10.1016/j.ceb.2016.02.021] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/09/2016] [Accepted: 02/25/2016] [Indexed: 11/22/2022]
Abstract
The plasma membrane serves as a barrier, separating the cell from its external environment. Simultaneously it acts as a site for information transduction, entry of nutrients, receptor signaling, and adapts to the shape of the cell. This requires local control of organization at multiple scales in this heterogeneous fluid lipid bilayer with a plethora of proteins and a closely juxtaposed dynamic cortical cytoskeleton. New membrane models highlight the influence of the underlying cortical actin on the diffusion of membrane components. Myosin motors as well as proteins that remodel actin filaments have additionally been implicated in defining the organization of many membrane constituents. Here we provide a perspective of the intimate relationship of the membrane lipid matrix and the underlying cytoskeleton.
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