1
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Ivanova JR, Benk AS, Schaefer JV, Dreier B, Hermann LO, Plückthun A, Missirlis D, Spatz JP. Designed Ankyrin Repeat Proteins as Actin Labels of Distinct Cytoskeletal Structures in Living Cells. ACS NANO 2024; 18:8919-8933. [PMID: 38489155 DOI: 10.1021/acsnano.3c12265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
The orchestrated assembly of actin and actin-binding proteins into cytoskeletal structures coordinates cell morphology changes during migration, cytokinesis, and adaptation to external stimuli. The accurate and unbiased visualization of the diverse actin assemblies within cells is an ongoing challenge. We describe here the identification and use of designed ankyrin repeat proteins (DARPins) as synthetic actin binders. Actin-binding DARPins were identified through ribosome display and validated biochemically. When introduced or expressed inside living cells, fluorescently labeled DARPins accumulated at actin filaments, validated through phalloidin colocalization on fixed cells. Nevertheless, different DARPins displayed different actin labeling patterns: some DARPins labeled efficiently dynamic structures, such as filopodia, lamellipodia, and blebs, while others accumulated primarily in stress fibers. This differential intracellular distribution correlated with DARPin-actin binding kinetics, as measured by fluorescence recovery after photobleaching experiments. Moreover, the rapid arrest of actin dynamics induced by pharmacological treatment led to the fast relocalization of DARPins. Our data support the hypothesis that the localization of actin probes depends on the inherent dynamic movement of the actin cytoskeleton. Compared to the widely used LifeAct probe, one DARPin exhibited enhanced signal-to-background ratio while retaining a similar ability to label stress fibers. In summary, we propose DARPins as promising actin-binding proteins for labeling or manipulation in living cells.
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Affiliation(s)
- Julia R Ivanova
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
- Heidelberg University, Faculty of Biosciences, 69120 Heidelberg, Germany
- Max Planck School Matter to Life, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Amelie S Benk
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
| | - Jonas V Schaefer
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- CSL Behring AG, 3014 Bern, Switzerland
| | - Birgit Dreier
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Leon O Hermann
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Dimitris Missirlis
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
- Institute for Molecular Systems Engineering and Advanced Materials, Heidelberg University, INF 225, D-69120 Heidelberg, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany
- Institute for Molecular Systems Engineering and Advanced Materials, Heidelberg University, INF 225, D-69120 Heidelberg, Germany
- Max Planck School Matter to Life, Jahnstrasse 29, 69120 Heidelberg, Germany
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2
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Yamashiro S, Rutkowski DM, Lynch KA, Liu Y, Vavylonis D, Watanabe N. Force transmission by retrograde actin flow-induced dynamic molecular stretching of Talin. Nat Commun 2023; 14:8468. [PMID: 38123541 PMCID: PMC10733299 DOI: 10.1038/s41467-023-44018-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023] Open
Abstract
Force transmission at integrin-based adhesions is important for cell migration and mechanosensing. Talin is an essential focal adhesion (FA) protein that links F-actin to integrins. F-actin constantly moves on FAs, yet how Talin simultaneously maintains the connection to F-actin and transmits forces to integrins remains unclear. Here we show a critical role of dynamic Talin unfolding in force transmission. Using single-molecule speckle microscopy, we found that the majority of Talin are bound only to either F-actin or the substrate, whereas 4.1% of Talin is linked to both structures via elastic transient clutch. By reconstituting Talin knockdown cells with Talin chimeric mutants, in which the Talin rod subdomains are replaced with the stretchable β-spectrin repeats, we show that the stretchable property is critical for force transmission. Simulations suggest that unfolding of the Talin rod subdomains increases in the linkage duration and work at FAs. This study elucidates a force transmission mechanism, in which stochastic molecular stretching bridges two cellular structures moving at different speeds.
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Affiliation(s)
- Sawako Yamashiro
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto, Japan.
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | | | - Kelli Ann Lynch
- Department of Physics, Lehigh University, Bethlehem, PA, USA
- University of South Florida, Tampa, FL, USA
| | - Ying Liu
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto, Japan
| | | | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto, Japan
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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3
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Smart K, Kramer AH, Smart S, Hodgson L, Sharp DJ. Fidgetin-like 2 depletion enhances cell migration by regulating GEF-H1, RhoA, and FAK. Biophys J 2023; 122:3600-3610. [PMID: 36523161 PMCID: PMC10541466 DOI: 10.1016/j.bpj.2022.12.018] [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: 08/22/2022] [Revised: 10/31/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
The microtubule (MT) cytoskeleton and its dynamics play an important role in cell migration. Depletion of the microtubule-severing enzyme Fidgetin-like 2 (FL2), a regulator of MT dynamics at the leading edge of migrating cells, leads to faster and more efficient cell migration. Here we examine how siRNA knockdown of FL2 increases cell motility. Förster resonance energy transfer biosensor studies shows that FL2 knockdown decreases activation of the p21 Rho GTPase, RhoA, and its activator GEF-H1. Immunofluorescence studies reveal that GEF-H1 is sequestered by the increased MT density resulting from FL2 depletion. Activation of the Rho GTPase, Rac1, however, does not change after FL2 knockdown. Furthermore, FL2 depletion leads to an increase in focal adhesion kinase activation at the leading edge, as shown by immunofluorescence studies, but no change in actin dynamics, as shown by fluorescence recovery after photobleaching. We believe these results expand our understanding of the role of MT dynamics in cell migration and offer new insights into RhoA and Rac1 regulation.
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Affiliation(s)
- Karishma Smart
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York
| | - Adam H Kramer
- Microcures, Inc., Research and Development, Bronx, New York
| | | | - Louis Hodgson
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York.
| | - David J Sharp
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York; Microcures, Inc., Research and Development, Bronx, New York.
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4
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Yamashiro S, Rutkowski DM, Ann Lynch K, Liu Y, Vavylonis D, Watanabe N. Force transmission by retrograde actin flow-induced dynamic molecular stretching of Talin. RESEARCH SQUARE 2023:rs.3.rs-3254213. [PMID: 37674715 PMCID: PMC10479399 DOI: 10.21203/rs.3.rs-3254213/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Force transmission at integrin-based adhesions is important for cell migration and mechanosensing. Talin is an essential focal adhesion (FA) protein that links F-actin to integrins. F-actin constantly moves on FAs, yet how Talin simultaneously maintains the connection to F-actin and transmits forces to integrins remains unclear. Here we show a critical role of dynamic Talin unfolding in force transmission. Using single-molecule speckle microscopy, we found that the majority of Talin are bound only to either F-actin or the substrate, whereas 4.1% of Talin is linked to both structures via elastic transient clutch. By reconstituting Talin knockdown cells with Talin chimeric mutants, in which the Talin rod subdomains are replaced with the stretchable β-spectrin repeats, we show that the stretchable property is critical for force transmission. Simulations suggest that unfolding of the Talin rod subdomains increases in the linkage duration and work at FAs. This study reveals a new mode of force transmission, in which stochastic molecular stretching bridges two cellular structures moving at different speeds.
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Affiliation(s)
- Sawako Yamashiro
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto Japan
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto Japan
| | | | - Kelli Ann Lynch
- Department of Physics, Lehigh University, Bethlehem, PA, USA
- University of South Florida, Tampa, FL, USA
| | - Ying Liu
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto Japan
| | | | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto Japan
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto Japan
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5
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Georgantzoglou A, Poplimont H, Walker HA, Lämmermann T, Sarris M. A two-step search and run response to gradients shapes leukocyte navigation in vivo. J Cell Biol 2022; 221:213303. [PMID: 35731205 PMCID: PMC9225946 DOI: 10.1083/jcb.202103207] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 02/03/2022] [Accepted: 05/20/2022] [Indexed: 12/17/2022] Open
Abstract
Migrating cells must interpret chemical gradients to guide themselves within tissues. A long-held principle is that gradients guide cells via reorientation of leading-edge protrusions. However, recent evidence indicates that protrusions can be dispensable for locomotion in some contexts, raising questions about how cells interpret endogenous gradients in vivo and whether other mechanisms are involved. Using laser wound assays in zebrafish to elicit acute endogenous gradients and quantitative analyses, we demonstrate a two-stage process for leukocyte chemotaxis in vivo: first a “search” phase, with stimulation of actin networks at the leading edge, cell deceleration, and turning. This is followed by a “run” phase, with fast actin flows, cell acceleration, and persistence. When actin dynamics are perturbed, cells fail to resolve the gradient, suggesting that pure spatial sensing of the gradient is insufficient for navigation. Our data suggest that cell contractility and actin flows provide memory for temporal sensing, while expansion of the leading edge serves to enhance gradient sampling.
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Affiliation(s)
- Antonios Georgantzoglou
- Department of Physiology, Development and Neuroscience, Downing Site, University of Cambridge, Cambridge, UK
| | - Hugo Poplimont
- Department of Physiology, Development and Neuroscience, Downing Site, University of Cambridge, Cambridge, UK
| | - Hazel A Walker
- Department of Physiology, Development and Neuroscience, Downing Site, University of Cambridge, Cambridge, UK
| | - Tim Lämmermann
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Milka Sarris
- Department of Physiology, Development and Neuroscience, Downing Site, University of Cambridge, Cambridge, UK
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6
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Evaluation of Stable LifeAct-mRuby2- and LAMP1-NeonGreen Expressing A549 Cell Lines for Investigation of Aspergillus fumigatus Interaction with Pulmonary Cells. Int J Mol Sci 2021; 22:ijms22115965. [PMID: 34073107 PMCID: PMC8198894 DOI: 10.3390/ijms22115965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 05/29/2021] [Indexed: 11/20/2022] Open
Abstract
Inhaled Aspergillus fumigatus spores can be internalized by alveolar type II cells. Cell lines stably expressing fluorescently labeled components of endocytic pathway enable investigations of intracellular organization during conidia internalization and measurement of the process kinetics. The goal of this report was to evaluate the methodological appliance of cell lines for studying fungal conidia internalization. We have generated A549 cell lines stably expressing fluorescently labeled actin (LifeAct-mRuby2) and late endosomal protein (LAMP1-NeonGreen) following an evaluation of cell-pathogen interactions in live and fixed cells. Our data show that the LAMP1-NeonGreen cell line can be used to visualize conidia co-localization with LAMP1 in live and fixed cells. However, caution is necessary when using LifeAct-mRuby2-cell lines as it may affect the conidia internalization dynamics.
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7
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Harris AR, Jreij P, Belardi B, Joffe AM, Bausch AR, Fletcher DA. Biased localization of actin binding proteins by actin filament conformation. Nat Commun 2020; 11:5973. [PMID: 33239610 PMCID: PMC7688639 DOI: 10.1038/s41467-020-19768-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 10/30/2020] [Indexed: 11/09/2022] Open
Abstract
The assembly of actin filaments into distinct cytoskeletal structures plays a critical role in cell physiology, but how proteins localize differentially to these structures within a shared cytoplasm remains unclear. Here, we show that the actin-binding domains of accessory proteins can be sensitive to filament conformational changes. Using a combination of live cell imaging and in vitro single molecule binding measurements, we show that tandem calponin homology domains (CH1-CH2) can be mutated to preferentially bind actin networks at the front or rear of motile cells. We demonstrate that the binding kinetics of CH1-CH2 domain mutants varies as actin filament conformation is altered by perturbations that include stabilizing drugs and other binding proteins. These findings suggest that conformational changes of actin filaments in cells could help to direct accessory binding proteins to different actin cytoskeletal structures through a biophysical feedback loop.
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Affiliation(s)
- Andrew R Harris
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Pamela Jreij
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Brian Belardi
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Aaron M Joffe
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Andreas R Bausch
- Lehrstuhl für Biophysik (E27), Technische Universität München, Garching, 85748, Germany
| | - Daniel A Fletcher
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA.
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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8
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Perfilov MM, Gurskaya NG, Serebrovskaya EO, Melnikov PA, Kharitonov SL, Lewis TR, Arshavsky VY, Baklaushev VP, Mishin AS, Lukyanov KA. Highly photostable fluorescent labeling of proteins in live cells using exchangeable coiled coils heterodimerization. Cell Mol Life Sci 2020; 77:4429-4440. [PMID: 31894363 PMCID: PMC7329588 DOI: 10.1007/s00018-019-03426-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 11/10/2019] [Accepted: 12/13/2019] [Indexed: 10/25/2022]
Abstract
Fluorescent proteins are commonly used to label target proteins in live cells. However, the conventional approach based on covalent fusion of targeted proteins with fluorescent protein probes is limited by the slow rate of fluorophore maturation and irretrievable loss of fluorescence due to photobleaching. Here, we report a genetically encoded protein labeling system utilizing transient interactions of small, 21-28 residues-long helical protein tags (K/E coils, KEC). In this system, a protein of interest, covalently tagged with a single coil, is visualized through binding to a cytoplasmic fluorescent protein carrying a complementary coil. The reversible heterodimerization of KECs, whose affinity can be tuned in a broad concentration range from nanomolar to micromolar, allows continuous exchange and replenishment of the tag bound to a targeted protein with the entire cytosolic pool of soluble fluorescent coils. We found that, under conditions of partial illumination of living cells, the photostability of labeling with KECs exceeds that of covalently fused fluorescent probes by approximately one order of magnitude. Similarly, single-molecule localization microscopy with KECs provided higher labeling density and allowed a much longer duration of imaging than with conventional fusion to fluorescent proteins. We also demonstrated that this method is well suited for imaging newly synthesized proteins, because the labeling efficiency by KECs is not dependent on the rate of fluorescent protein maturation. In conclusion, KECs can be used to visualize various target proteins which are directly exposed to the cytosol, thereby enabling their advanced characterization in time and space.
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Affiliation(s)
- Maxim M Perfilov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya St. 16/10, 117997, Moscow, Russia
| | - Nadya G Gurskaya
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya St. 16/10, 117997, Moscow, Russia
- Pirogov Russian National Research Medical University, Ostrovitianov St. 1, 117997, Moscow, Russia
| | - Ekaterina O Serebrovskaya
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya St. 16/10, 117997, Moscow, Russia
- Department of Ophthalmology, Duke University, Durham, NC, 27710, USA
| | - Pavel A Melnikov
- Serbsky National Medical Research Center for Psychiatry and Narcology, Kropotkinsky Lane 23, 119034, Moscow, Russia
| | - Sergey L Kharitonov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya St. 16/10, 117997, Moscow, Russia
| | - Tylor R Lewis
- Department of Ophthalmology, Duke University, Durham, NC, 27710, USA
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University, Durham, NC, 27710, USA
- Department of Pharmacology, Duke University, Durham, NC, 27710, USA
| | - Vladimir P Baklaushev
- Federal Research and Clinical Center of Specialized Medical Care and Medical Technologies, FMBA of Russia, Orekhovy Blvd. 28, 115682, Moscow, Russia
| | - Alexander S Mishin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya St. 16/10, 117997, Moscow, Russia.
| | - Konstantin A Lukyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya St. 16/10, 117997, Moscow, Russia.
- Skolkovo Institute of Science and Technology, Bolshoy Blvd. 30, 121205, Moscow, Russia.
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9
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Yonamine Y, Hiramatsu K, Ideguchi T, Ito T, Fujiwara T, Miura Y, Goda K, Hoshino Y. Spatiotemporal monitoring of intracellular metabolic dynamics by resonance Raman microscopy with isotope labeling. RSC Adv 2020; 10:16679-16686. [PMID: 35498863 PMCID: PMC9053077 DOI: 10.1039/d0ra02803g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 04/20/2020] [Indexed: 01/18/2023] Open
Abstract
We probed production process of a cellular metabolite with a stable isotope-labeled substrate exposed to various conditions.
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Affiliation(s)
- Yusuke Yonamine
- Research Institute for Electronic Science
- Hokkaido University
- Sapporo 001-0021
- Japan
| | - Kotaro Hiramatsu
- Department of Chemistry
- The University of Tokyo
- Tokyo 113-0033
- Japan
- Research Centre for Spectrochemistry
| | - Takuro Ideguchi
- Research Centre for Spectrochemistry
- The University of Tokyo
- Tokyo 113-0033
- Japan
- PRESTO
| | - Takuro Ito
- Japan Science and Technology Agency
- Kawaguchi-shi
- Japan
| | - Tomomi Fujiwara
- Department of Chemical Engineering
- Kyushu University
- Fukuoka 819-0395
- Japan
| | - Yoshiko Miura
- Department of Chemical Engineering
- Kyushu University
- Fukuoka 819-0395
- Japan
| | - Keisuke Goda
- Department of Chemistry
- The University of Tokyo
- Tokyo 113-0033
- Japan
- Japan Science and Technology Agency
| | - Yu Hoshino
- Department of Chemical Engineering
- Kyushu University
- Fukuoka 819-0395
- Japan
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10
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Koseki K, Taniguchi D, Yamashiro S, Mizuno H, Vavylonis D, Watanabe N. Lamellipodium tip actin barbed ends serve as a force sensor. Genes Cells 2019; 24:705-718. [PMID: 31514256 DOI: 10.1111/gtc.12720] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 09/04/2019] [Accepted: 09/04/2019] [Indexed: 01/31/2023]
Abstract
Cells change direction of migration by sensing rigidity of environment and traction force, yet its underlying mechanism is unclear. Here, we show that tip actin barbed ends serve as an active "force sensor" at the leading edge. We established a method to visualize intracellular single-molecule fluorescent actin through an elastic culture substrate. We found that immediately after cell edge stretch, actin assembly increased specifically at the lamellipodium tip. The rate of actin assembly increased with increasing stretch speed. Furthermore, tip actin polymerization remained elevated at the subsequent hold step, which was accompanied by a decrease in the load on the tip barbed ends. Stretch-induced tip actin polymerization was still observed without either the WAVE complex or Ena/VASP proteins. The observed relationships between forces and tip actin polymerization are consistent with a force-velocity relationship as predicted by the Brownian ratchet mechanism. Stretch caused extra membrane protrusion with respect to the stretched substrate and increased local tip polymerization by >5% of total cellular actin in 30 s. Our data reveal that augmentation of lamellipodium tip actin assembly is directly coupled to the load decrease, which may serve as a force sensor for directed cell protrusion.
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Affiliation(s)
- Kazuma Koseki
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Daisuke Taniguchi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Sawako Yamashiro
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto, Japan
| | - Hiroaki Mizuno
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto, Japan
| | | | - Naoki Watanabe
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto, Japan
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11
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Yamashiro S, Watanabe N. Quantitative high-precision imaging of myosin-dependent filamentous actin dynamics. J Muscle Res Cell Motil 2019; 41:163-173. [PMID: 31313218 DOI: 10.1007/s10974-019-09541-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/10/2019] [Indexed: 12/20/2022]
Abstract
Over recent decades, considerable effort has been made to understand how mechanical stress applied to the actin network alters actin assembly and disassembly dynamics. However, there are conflicting reports concerning the issue both in vitro and in cells. In this review, we discuss concerns regarding previous quantitative live-cell experiments that have attempted to evaluate myosin regulation of filamentous actin (F-actin) turnover. In particular, we highlight an error-generating mechanism in quantitative live-cell imaging, namely convection-induced misdistribution of actin-binding probes. Direct observation of actin turnover at the single-molecule level using our improved electroporation-based Single-Molecule Speckle (eSiMS) microscopy technique overcomes these concerns. We introduce our recent single-molecule analysis that unambiguously demonstrates myosin-dependent regulation of F-actin stability in live cells. We also discuss the possible application of eSiMS microscopy in the analysis of actin remodeling in striated muscle cells.
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Affiliation(s)
- Sawako Yamashiro
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan. .,Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
| | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan.,Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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