1
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Werner ME, Ray DD, Breen C, Staddon MF, Jug F, Banerjee S, Maddox AS. Mechanical and biochemical feedback combine to generate complex contractile oscillations in cytokinesis. Curr Biol 2024; 34:3201-3214.e5. [PMID: 38991614 DOI: 10.1016/j.cub.2024.06.037] [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: 12/08/2023] [Revised: 04/22/2024] [Accepted: 06/13/2024] [Indexed: 07/13/2024]
Abstract
The actomyosin cortex is an active material that generates force to drive shape changes via cytoskeletal remodeling. Cytokinesis is the essential cell division event during which a cortical actomyosin ring closes to separate two daughter cells. Our active gel theory predicted that actomyosin systems controlled by a biochemical oscillator and experiencing mechanical strain would exhibit complex spatiotemporal behavior. To test whether active materials in vivo exhibit spatiotemporally complex kinetics, we imaged the C. elegans embryo with unprecedented temporal resolution and discovered that sections of the cytokinetic cortex undergo periodic phases of acceleration and deceleration. Contractile oscillations exhibited a range of periodicities, including those much longer periods than the timescale of RhoA pulses, which was shorter in cytokinesis than in any other biological context. Modifying mechanical feedback in vivo or in silico revealed that the period of contractile oscillation is prolonged as a function of the intensity of mechanical feedback. Fast local ring ingression occurs where speed oscillations have long periods, likely due to increased local stresses and, therefore, mechanical feedback. Fast ingression also occurs where material turnover is high, in vivo and in silico. We propose that downstream of initiation by pulsed RhoA activity, mechanical feedback, including but not limited to material advection, extends the timescale of contractility beyond that of biochemical input and, therefore, makes it robust to fluctuations in activation. Circumferential propagation of contractility likely allows for sustained contractility despite cytoskeletal remodeling necessary to recover from compaction. Thus, like biochemical feedback, mechanical feedback affords active materials responsiveness and robustness.
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Affiliation(s)
- Michael E Werner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Dylan D Ray
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Coleman Breen
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Michael F Staddon
- Center for Systems Biology Dresden, Max Planck Institute for the Physics of Complex Systems, and Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Florian Jug
- Computational Biology Research Centre, Human Technopole, Milan, Italy
| | - Shiladitya Banerjee
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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2
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Effiong UM, Khairandish H, Ramirez-Velez I, Wang Y, Belardi B. Turn-on protein switches for controlling actin binding in cells. Nat Commun 2024; 15:5840. [PMID: 38992021 PMCID: PMC11239668 DOI: 10.1038/s41467-024-49934-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 06/26/2024] [Indexed: 07/13/2024] Open
Abstract
Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP's influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality and multiplexing. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into structures to control cell and tissue shape and behavior.
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Affiliation(s)
- Unyime M Effiong
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Hannah Khairandish
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Isabela Ramirez-Velez
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Yanran Wang
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Brian Belardi
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
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3
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Chikireddy J, Lengagne L, Le Borgne R, Durieu C, Wioland H, Romet-Lemonne G, Jégou A. Fascin-induced bundling protects actin filaments from disassembly by cofilin. J Cell Biol 2024; 223:e202312106. [PMID: 38497788 PMCID: PMC10949937 DOI: 10.1083/jcb.202312106] [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: 12/20/2023] [Revised: 02/26/2024] [Accepted: 02/29/2024] [Indexed: 03/19/2024] Open
Abstract
Actin filament turnover plays a central role in shaping actin networks, yet the feedback mechanism between network architecture and filament assembly dynamics remains unclear. The activity of ADF/cofilin, the main protein family responsible for filament disassembly, has been mainly studied at the single filament level. This study unveils that fascin, by crosslinking filaments into bundles, strongly slows down filament disassembly by cofilin. We show that this is due to a markedly slower initiation of the first cofilin clusters, which occurs up to 100-fold slower on large bundles compared with single filaments. In contrast, severing at cofilin cluster boundaries is unaffected by fascin bundling. After the formation of an initial cofilin cluster on a filament within a bundle, we observed the local removal of fascin. Notably, the formation of cofilin clusters on adjacent filaments is highly enhanced, locally. We propose that this interfilament cooperativity arises from the local propagation of the cofilin-induced change in helicity from one filament to the other filaments of the bundle. Overall, taking into account all the above reactions, we reveal that fascin crosslinking slows down the disassembly of actin filaments by cofilin. These findings highlight the important role played by crosslinkers in tuning actin network turnover by modulating the activity of other regulatory proteins.
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Affiliation(s)
| | - Léana Lengagne
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Rémi Le Borgne
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Catherine Durieu
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Hugo Wioland
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | | | - Antoine Jégou
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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4
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Homa KE, Hocky GM, Suarez C, Kovar DR. Arp2/3 complex- and formin-mediated actin cytoskeleton networks facilitate actin binding protein sorting in fission yeast. Eur J Cell Biol 2024; 103:151404. [PMID: 38493594 PMCID: PMC11211059 DOI: 10.1016/j.ejcb.2024.151404] [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: 11/07/2023] [Revised: 03/01/2024] [Accepted: 03/13/2024] [Indexed: 03/19/2024] Open
Abstract
While it is well-established that F-actin networks with specific organizations and dynamics are tightly regulated by distinct sets of associated actin-binding proteins (ABPs), how ABPs self-sort to particular F-actin networks remains largely unclear. We report that actin assembly factors Arp2/3 complex and formin Cdc12 tune the association of ABPs fimbrin Fim1 and tropomyosin Cdc8 to different F-actin networks in fission yeast. Genetic and pharmacological disruption of F-actin networks revealed that Fim1 is preferentially directed to Arp2/3-complex mediated actin patches, whereas Cdc8 is preferentially targeted to formin Cdc12-mediated filaments in the contractile ring. To investigate the role of Arp2/3 complex- and formin Cdc12-mediated actin assembly, we used four-color TIRF microscopy to observe the in vitro reconstitution of ABP sorting with purified proteins. Fim1 or Cdc8 alone bind similarly well to filaments assembled by either assembly factor. However, in 'competition' reactions containing both actin assembly factors and both ABPs, ∼2.0-fold more Fim1 and ∼3.5-fold more Cdc8 accumulates on Arp2/3 complex branch points and formin Cdc12-assembled actin filaments, respectively. These findings indicate that F-actin assembly factors Arp2/3 complex and formin Cdc12 help facilitate the recruitment of specific ABPs, thereby tuning ABP sorting and subsequently establishing the identity of F-actin networks in fission yeast.
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Affiliation(s)
- Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, United States
| | - Glen M Hocky
- Department of Chemistry, New York University, New York, NY, United States
| | - Cristian Suarez
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, United States
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, United States; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, United States.
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5
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Ioannou IA, Brooks NJ, Kuimova MK, Elani Y. Visualizing Actin Packing and the Effects of Actin Attachment on Lipid Membrane Viscosity Using Molecular Rotors. JACS AU 2024; 4:2041-2049. [PMID: 38818078 PMCID: PMC11134356 DOI: 10.1021/jacsau.4c00237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 06/01/2024]
Abstract
The actin cytoskeleton and its elaborate interplay with the plasma membrane participate in and control numerous biological processes in eukaryotic cells. Malfunction of actin networks and changes in their dynamics are related to various diseases, from actin myopathies to uncontrolled cell growth and tumorigenesis. Importantly, the biophysical and mechanical properties of actin and its assemblies are deeply intertwined with the biological functions of the cytoskeleton. Novel tools to study actin and its associated biophysical features are, therefore, of prime importance. Here we develop a new approach which exploits fluorescence lifetime imaging microscopy (FLIM) and environmentally sensitive fluorophores termed molecular rotors, acting as quantitative microviscosity sensors, to monitor dynamic viscoelastic properties of both actin structures and lipid membranes. In order to reproduce a minimal actin cortex in synthetic cell models, we encapsulated and attached actin networks to the lipid bilayer of giant unilamellar vesicles (GUVs). Using a cyanine-based molecular rotor, DiSC2(3), we show that different types of actin bundles are characterized by distinct packing, which can be spatially resolved using FLIM. Similarly, we show that a lipid bilayer-localized molecular rotor can monitor the effects of attaching cross-linked actin networks to the lipid membrane, revealing an increase in membrane viscosity upon actin attachment. Our approach bypasses constraints associated with existing methods for actin imaging, many of which lack the capability for direct visualization of biophysical properties. It can therefore contribute to a deeper understanding of the role that actin plays in fundamental biological processes and help elucidate the underlying biophysics of actin-related diseases.
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Affiliation(s)
- Ion A. Ioannou
- Department
of Chemistry, Imperial College London, Molecular
Sciences Research Hub, London W12 0BZ, U.K.
- Department
of Chemical Engineering, Imperial College
London, South Kensington, London SW7 2AZ, U.K.
| | - Nickolas J. Brooks
- Department
of Chemistry, Imperial College London, Molecular
Sciences Research Hub, London W12 0BZ, U.K.
| | - Marina K. Kuimova
- Department
of Chemistry, Imperial College London, Molecular
Sciences Research Hub, London W12 0BZ, U.K.
| | - Yuval Elani
- Department
of Chemical Engineering, Imperial College
London, South Kensington, London SW7 2AZ, U.K.
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6
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Morales EA, Fitz GN, Tyska MJ. Mitotic spindle positioning protein (MISP) preferentially binds to aged F-actin. J Biol Chem 2024; 300:107279. [PMID: 38588808 PMCID: PMC11101845 DOI: 10.1016/j.jbc.2024.107279] [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: 10/01/2023] [Revised: 03/14/2024] [Accepted: 04/01/2024] [Indexed: 04/10/2024] Open
Abstract
Actin bundling proteins crosslink filaments into polarized structures that shape and support membrane protrusions including filopodia, microvilli, and stereocilia. In the case of epithelial microvilli, mitotic spindle positioning protein (MISP) is an actin bundler that localizes specifically to the basal rootlets, where the pointed ends of core bundle filaments converge. Previous studies established that MISP is prevented from binding more distal segments of the core bundle by competition with other actin-binding proteins. Yet whether MISP holds a preference for binding directly to rootlet actin remains an open question. By immunostaining native intestinal tissue sections, we found that microvillar rootlets are decorated with the severing protein, cofilin, suggesting high levels of ADP-actin in these structures. Using total internal reflection fluorescence microscopy assays, we also found that purified MISP exhibits a binding preference for ADP- versus ADP-Pi-actin-containing filaments. Consistent with this, assays with actively growing actin filaments revealed that MISP binds at or near their pointed ends. Moreover, although substrate attached MISP assembles filament bundles in parallel and antiparallel configurations, in solution MISP assembles parallel bundles consisting of multiple filaments exhibiting uniform polarity. These discoveries highlight nucleotide state sensing as a mechanism for sorting actin bundlers along filaments and driving their accumulation near filament ends. Such localized binding might drive parallel bundle formation and/or locally modulate bundle mechanical properties in microvilli and related protrusions.
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Affiliation(s)
- E Angelo Morales
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Gillian N Fitz
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA.
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7
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Sakamoto R, Murrell MP. F-actin architecture determines the conversion of chemical energy into mechanical work. Nat Commun 2024; 15:3444. [PMID: 38658549 PMCID: PMC11043346 DOI: 10.1038/s41467-024-47593-x] [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: 10/13/2023] [Accepted: 04/03/2024] [Indexed: 04/26/2024] Open
Abstract
Mechanical work serves as the foundation for dynamic cellular processes, ranging from cell division to migration. A fundamental driver of cellular mechanical work is the actin cytoskeleton, composed of filamentous actin (F-actin) and myosin motors, where force generation relies on adenosine triphosphate (ATP) hydrolysis. F-actin architectures, whether bundled by crosslinkers or branched via nucleators, have emerged as pivotal regulators of myosin II force generation. However, it remains unclear how distinct F-actin architectures impact the conversion of chemical energy to mechanical work. Here, we employ in vitro reconstitution of distinct F-actin architectures with purified components to investigate their influence on myosin ATP hydrolysis (consumption). We find that F-actin bundles composed of mixed polarity F-actin hinder network contraction compared to non-crosslinked network and dramatically decelerate ATP consumption rates. Conversely, linear-nucleated networks allow network contraction despite reducing ATP consumption rates. Surprisingly, branched-nucleated networks facilitate high ATP consumption without significant network contraction, suggesting that the branched network dissipates energy without performing work. This study establishes a link between F-actin architecture and myosin energy consumption, elucidating the energetic principles underlying F-actin structure formation and the performance of mechanical work.
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Affiliation(s)
- Ryota Sakamoto
- Department of Biomedical Engineering, Yale University, 10 Hillhouse Avenue, New Haven, CT, USA
- Systems Biology Institute, 850 West Campus Drive, West Haven, CT, USA
| | - Michael P Murrell
- Department of Biomedical Engineering, Yale University, 10 Hillhouse Avenue, New Haven, CT, USA.
- Systems Biology Institute, 850 West Campus Drive, West Haven, CT, USA.
- Department of Physics, Yale University, 217 Prospect Street, New Haven, CT, USA.
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8
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Sherer LA, Mahanta B, Courtemanche N. Computational tools for quantifying actin filament numbers, lengths, and bundling. Biol Open 2024; 13:bio060267. [PMID: 38372564 PMCID: PMC10924227 DOI: 10.1242/bio.060267] [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: 12/01/2023] [Accepted: 02/08/2024] [Indexed: 02/20/2024] Open
Abstract
The actin cytoskeleton is a dynamic filamentous network that assembles into specialized structures to enable cells to perform essential processes. Direct visualization of fluorescently-labeled cytoskeletal proteins has provided numerous insights into the dynamic processes that govern the assembly of actin-based structures. However, accurate analysis of these experiments is often complicated by the interdependent and kinetic natures of the reactions involved. It is often challenging to disentangle these processes to accurately track their evolution over time. Here, we describe two programs written in the MATLAB programming language that facilitate counting, length measurements, and quantification of bundling of actin filaments visualized in fluorescence micrographs. To demonstrate the usefulness of our programs, we describe their application to the analysis of two representative reactions: (1) a solution of pre-assembled filaments under equilibrium conditions, and (2) a reaction in which actin filaments are crosslinked together over time. We anticipate that these programs can be applied to extract equilibrium and kinetic information from a broad range of actin-based reactions, and that their usefulness can be expanded further to investigate the assembly of other biopolymers.
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Affiliation(s)
- Laura A. Sherer
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Biswaprakash Mahanta
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Naomi Courtemanche
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
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9
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Gong R, Reynolds MJ, Carney KR, Hamilton K, Bidone TC, Alushin GM. Fascin structural plasticity mediates flexible actin bundle construction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.03.574123. [PMID: 38260322 PMCID: PMC10802278 DOI: 10.1101/2024.01.03.574123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Fascin crosslinks actin filaments (F-actin) into bundles that support tubular membrane protrusions including filopodia and stereocilia. Fascin dysregulation drives aberrant cell migration during metastasis, and fascin inhibitors are under development as cancer therapeutics. Here, we use cryo-electron microscopy, cryo-electron tomography coupled with custom denoising, and computational modeling to probe fascin's F-actin crosslinking mechanisms across spatial scales. Our fascin crossbridge structure reveals an asymmetric F-actin binding conformation that is allosterically blocked by the inhibitor G2. Reconstructions of seven-filament hexagonal bundle elements, variability analysis, and simulations show how structural plasticity enables fascin to bridge varied inter-filament orientations, accommodating mismatches between F-actin's helical symmetry and bundle hexagonal packing. Tomography of many-filament bundles and modeling uncovers geometric rules underlying emergent fascin binding patterns, as well as the accumulation of unfavorable crosslinks that limit bundle size. Collectively, this work shows how fascin harnesses fine-tuned nanoscale structural dynamics to build and regulate micron-scale F-actin bundles.
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Affiliation(s)
- Rui Gong
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Matthew J. Reynolds
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Keith R. Carney
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
| | - Keith Hamilton
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Tamara C. Bidone
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
| | - Gregory M. Alushin
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
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10
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Sabo J, Dujava Zdimalova M, Slater PG, Dostal V, Herynek S, Libusova L, Lowery LA, Braun M, Lansky Z. CKAP5 enables formation of persistent actin bundles templated by dynamically instable microtubules. Curr Biol 2024; 34:260-272.e7. [PMID: 38086388 PMCID: PMC10841699 DOI: 10.1016/j.cub.2023.11.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 10/06/2023] [Accepted: 11/14/2023] [Indexed: 01/25/2024]
Abstract
Cytoskeletal rearrangements and crosstalk between microtubules and actin filaments are vital for living organisms. Recently, an abundantly present microtubule polymerase, CKAP5 (XMAP215 homolog), has been reported to play a role in mediating crosstalk between microtubules and actin filaments in the neuronal growth cones. However, the molecular mechanism of this process is unknown. Here, we demonstrate, in a reconstituted system, that CKAP5 enables the formation of persistent actin bundles templated by dynamically instable microtubules. We explain the templating by the difference in CKAP5 binding to microtubules and actin filaments. Binding to the microtubule lattice with higher affinity, CKAP5 enables the formation of actin bundles exclusively on the microtubule lattice, at CKAP5 concentrations insufficient to support any actin bundling in the absence of microtubules. Strikingly, when the microtubules depolymerize, actin bundles prevail at the positions predetermined by the microtubules. We propose that the local abundance of available CKAP5-binding sites in actin bundles allows the retention of CKAP5, resulting in persisting actin bundles. In line with our observations, we found that reducing CKAP5 levels in vivo results in a decrease in actin-microtubule co-localization in growth cones and specifically decreases actin intensity at microtubule plus ends. This readily suggests a mechanism explaining how exploratory microtubules set the positions of actin bundles, for example, in cytoskeleton-rich neuronal growth cones.
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Affiliation(s)
- Jan Sabo
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 12800, Czech Republic
| | - Michaela Dujava Zdimalova
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic
| | - Paula G Slater
- Departamento de Ciencias Biológicas y Químicas, Facultad de Medicina y Ciencias, Universidad San Sebastián, Campus Los Leones, Lota 2465, Providencia, Santiago 7510602, Chile
| | - Vojtech Dostal
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Stepan Herynek
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic; Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Lenka Libusova
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Laura A Lowery
- Department of Medicine, Section of Hematology/Oncology, Boston University and Boston Medical Center, Boston, MA 02118, USA
| | - Marcus Braun
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic.
| | - Zdenek Lansky
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic.
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11
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Villagomez FR, Lang J, Webb P, Neville M, Woodruff ER, Bitler BG. Claudin-4 modulates autophagy via SLC1A5/LAT1 as a tolerance mechanism for genomic instability in ovarian cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576263. [PMID: 38293054 PMCID: PMC10827183 DOI: 10.1101/2024.01.18.576263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Genome instability is key for tumor heterogeneity and derives from defects in cell division and DNA damage repair. Tumors show tolerance for this characteristic, but its accumulation is regulated somehow to avoid catastrophic chromosomal alterations and cell death. Claudin-4 is upregulated and closely associated with genome instability and worse patient outcome in ovarian cancer. This protein is commonly described as a junctional protein participating in processes such as cell proliferation and DNA repair. However, its biological association with genomic instability is still poorly-understood. Here, we used CRISPRi and a claudin mimic peptide (CMP) to modulate the cladudin-4 expression and its function, respectively in in-vitro (high-grade serous carcinoma cells) and in-vivo (patient-derived xenograft in a humanized-mice model) systems. We found that claudin-4 promotes a protective cellular-mechanism that links cell-cell junctions to genome integrity. Disruption of this axis leads to irregular cellular connections and cell cycle that results in chromosomal alterations, a phenomenon associated with a novel functional link between claudin-4 and SLC1A5/LAT1 in regulating autophagy. Consequently, claudin-4's disruption increased autophagy and associated with engulfment of cytoplasm-localized DNA. Furthermore, the claudin-4/SLC1A5/LAT1 biological axis correlates with decrease ovarian cancer patient survival and targeting claudin-4 in-vivo with CMP resulted in increased niraparib (PARPi) efficacy, correlating with increased tumoral infiltration of T CD8+ lymphocytes. Our results show that the upregulation of claudin-4 enables a mechanism that promotes tolerance to genomic instability and immune evasion in ovarian cancer; thus, suggesting the potential of claudin-4 as a translational target for enhancing ovarian cancer treatment.
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12
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Werner ME, Ray DD, Breen C, Staddon MF, Jug F, Banerjee S, Maddox AS. Mechanical positive feedback and biochemical negative feedback combine to generate complex contractile oscillations in cytokinesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.01.569672. [PMID: 38076901 PMCID: PMC10705528 DOI: 10.1101/2023.12.01.569672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
Contractile force generation by the cortical actomyosin cytoskeleton is essential for a multitude of biological processes. The actomyosin cortex behaves as an active material that drives local and large-scale shape changes via cytoskeletal remodeling in response to biochemical cues and feedback loops. Cytokinesis is the essential cell division event during which a cortical actomyosin ring generates contractile force to change cell shape and separate two daughter cells. Our recent work with active gel theory predicts that actomyosin systems under the control of a biochemical oscillator and experiencing mechanical strain will exhibit complex spatiotemporal behavior, but cytokinetic contractility was thought to be kinetically simple. To test whether active materials in vivo exhibit spatiotemporally complex kinetics, we used 4-dimensional imaging with unprecedented temporal resolution and discovered sections of the cytokinetic cortex undergo periodic phases of acceleration and deceleration. Quantification of ingression speed oscillations revealed wide ranges of oscillation period and amplitude. In the cytokinetic ring, activity of the master regulator RhoA pulsed with a timescale of approximately 20 seconds, shorter than that reported for any other biological context. Contractility oscillated with 20-second periodicity and with much longer periods. A combination of in vivo and in silico approaches to modify mechanical feedback revealed that the period of contractile oscillation is prolonged as a function of the intensity of mechanical feedback. Effective local ring ingression is characterized by slower speed oscillations, likely due to increased local stresses and therefore mechanical feedback. Fast ingression also occurs where material turnover is high, in vivo and in silico . We propose that downstream of initiation by pulsed RhoA activity, mechanical positive feedback, including but not limited to material advection, extends the timescale of contractility beyond that of biochemical input and therefore makes it robust to fluctuations in activation. Circumferential propagation of contractility likely allows sustained contractility despite cytoskeletal remodeling necessary to recover from compaction. Our work demonstrates that while biochemical feedback loops afford systems responsiveness and robustness, mechanical feedback must also be considered to describe and understand the behaviors of active materials in vivo .
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13
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Suarez C, Winkelman JD, Harker AJ, Ye HJ, McCall PM, Morganthaler AN, Gardel ML, Kovar DR. Reconstitution of the transition from a lamellipodia- to filopodia-like actin network with purified proteins. Eur J Cell Biol 2023; 102:151367. [PMID: 37890285 DOI: 10.1016/j.ejcb.2023.151367] [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: 06/22/2023] [Revised: 09/29/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023] Open
Abstract
How cells utilize complex mixtures of actin binding proteins to assemble and maintain functionally diverse actin filament networks with distinct architectures and dynamics within a common cytoplasm is a longstanding question in cell biology. A compelling example of complex and specialized actin structures in cells are filopodia which sense extracellular chemical and mechanical signals to help steer motile cells. Filopodia have distinct actin architecture, composed of long, parallel actin filaments bundled by fascin, which form finger-like membrane protrusions. Elongation of the parallel actin filaments in filopodia can be mediated by two processive actin filament elongation factors, formin and Ena/VASP, which localize to the tips of filopodia. There remains debate as to how the architecture of filopodia are generated, with one hypothesis proposing that filopodia are generated from the lamellipodia, which consists of densely packed, branched actin filaments nucleated by Arp2/3 complex and kept short by capping protein. It remains unclear if different actin filament elongation factors are necessary and sufficient to facilitate the emergence of filopodia with diverse characteristics from a highly dense network of short-branched capped filaments. To address this question, we combined bead motility and micropatterning biomimetic assays with multi-color Total Internal Reflection Fluorescence microscopy imaging, to successfully reconstitute the formation of filopodia-like networks (FLN) from densely-branched lamellipodia-like networks (LLN) with eight purified proteins (actin, profilin, Arp2/3 complex, Wasp pWA, fascin, capping protein, VASP and formin mDia2). Saturating capping protein concentrations inhibit FLN assembly, but the addition of either formin or Ena/VASP differentially rescues the formation of FLN from LLN. Specifically, we found that formin/mDia2-generated FLNs are relatively long and lack capping protein, whereas VASP-generated FLNs are comparatively short and contain capping protein, indicating that the actin elongation factor can affect the architecture and composition of FLN emerging from LLN. Our biomimetic reconstitution systems reveal that formin or VASP are necessary and sufficient to induce the transition from a LLN to a FLN, and establish robust in vitro platforms to investigate FLN assembly mechanisms.
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Affiliation(s)
- Cristian Suarez
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA.
| | - Jonathan D Winkelman
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Alyssa J Harker
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Hannah J Ye
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Patrick M McCall
- Department of Physics, The University of Chicago, Chicago, IL 60637, USA; James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Alisha N Morganthaler
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Margaret L Gardel
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA; Department of Physics, The University of Chicago, Chicago, IL 60637, USA; James Franck Institute, The University of Chicago, Chicago, IL 60637, USA; Pritzker School for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA; Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA.
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14
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Effiong UM, Khairandish H, Ramirez-Velez I, Wang Y, Belardi B. Turn-On Protein Switches for Controlling Actin Binding in Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.561921. [PMID: 37961502 PMCID: PMC10634840 DOI: 10.1101/2023.10.26.561921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP's influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into new structures to control cell and tissue shape and behavior.
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Affiliation(s)
- Unyime M. Effiong
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Hannah Khairandish
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Isabela Ramirez-Velez
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Yanran Wang
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Brian Belardi
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
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15
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Morales EA, Tyska MJ. Mitotic spindle positioning protein (MISP) is an actin bundler that senses ADP-actin and binds near the pointed ends of filaments. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.05.539649. [PMID: 37205433 PMCID: PMC10187293 DOI: 10.1101/2023.05.05.539649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Actin bundling proteins crosslink filaments into polarized structures that shape and support membrane protrusions including filopodia, microvilli, and stereocilia. In the case of epithelial microvilli, mitotic spindle positioning protein (MISP) is an actin bundler that localizes specifically to the basal rootlets, where the pointed ends of core bundle filaments converge. Previous studies established that MISP is prevented from binding more distal segments of the core bundle by competition with other actin binding proteins. Yet whether MISP holds a preference for binding directly to rootlet actin remains an open question. Using in vitro TIRF microscopy assays, we found that MISP exhibits a clear binding preference for filaments enriched in ADP-actin monomers. Consistent with this, assays with actively growing actin filaments revealed that MISP binds at or near their pointed ends. Moreover, although substrate attached MISP assembles filament bundles in parallel and antiparallel configurations, in solution MISP assembles parallel bundles consisting of multiple filaments exhibiting uniform polarity. These discoveries highlight nucleotide state sensing as a mechanism for sorting actin bundlers along filaments and driving their accumulation near filament ends. Such localized binding might drive parallel bundle formation and/or locally modulate bundle mechanical properties in microvilli and related protrusions.
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16
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Nakamura M, Hui J, Parkhurst SM. Bending actin filaments: twists of fate. Fac Rev 2023; 12:7. [PMID: 37081903 PMCID: PMC10111394 DOI: 10.12703/r/12-7] [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] [Indexed: 04/22/2023] Open
Abstract
In many cellular contexts, intracellular actomyosin networks must generate directional forces to carry out cellular tasks such as migration and endocytosis, which play important roles during normal developmental processes. A number of different actin binding proteins have been identified that form linear or branched actin, and that regulate these filaments through activities such as bundling, crosslinking, and depolymerization to create a wide variety of functional actin assemblies. The helical nature of actin filaments allows them to better accommodate tensile stresses by untwisting, as well as to bend to great curvatures without breaking. Interestingly, this latter property, the bending of actin filaments, is emerging as an exciting new feature for determining dynamic actin configurations and functions. Indeed, recent studies using in vitro assays have found that proteins including IQGAP, Cofilin, Septins, Anillin, α-Actinin, Fascin, and Myosins-alone or in combination-can influence the bending or curvature of actin filaments. This bending increases the number and types of dynamic assemblies that can be generated, as well as the spectrum of their functions. Intriguingly, in some cases, actin bending creates directionality within a cell, resulting in a chiral cell shape. This actin-dependent cell chirality is highly conserved in vertebrates and invertebrates and is essential for cell migration and breaking L-R symmetry of tissues/organs. Here, we review how different types of actin binding protein can bend actin filaments, induce curved filament geometries, and how they impact on cellular functions.
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Affiliation(s)
- Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Justin Hui
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Susan M Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
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17
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Tang Q, Pollard LW, Homa KE, Kovar DR, Trybus KM. Acetylation of fission yeast tropomyosin does not promote differential association with cognate formins. Cytoskeleton (Hoboken) 2023; 80:77-92. [PMID: 36692369 PMCID: PMC10121778 DOI: 10.1002/cm.21745] [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: 11/07/2022] [Revised: 01/02/2023] [Accepted: 01/17/2023] [Indexed: 01/25/2023]
Abstract
It was proposed from cellular studies that S. pombe tropomyosin Cdc8 (Tpm) segregates into two populations due to the presence or absence of an amino-terminal acetylation that specifies which formin-mediated F-actin networks it binds, but with no supporting biochemistry. To address this mechanism in vitro, we developed methods for S. pombe actin expression in Sf9 cells. We then employed 3-color TIRF microscopy using all recombinant S. pombe proteins to probe in vitro multicomponent mechanisms involving actin, acetylated and unacetylated Tpm, formins, and myosins. Acetyl-Tpm exhibits tight binding to actin in contrast to weaker binding by unacetylated Tpm. In disagreement with the differential recruitment model, Tpm showed no preferential binding to filaments assembled by the FH1-FH2-domains of two S. pombe formins, nor did Tpm binding have any bias towards the growing formin-bound actin filament barbed end. Although our in vitro findings do not support a direct formin-tropomyosin interaction, it is possible that formins bias differential tropomyosin isoform recruitment through undiscovered mechanisms. Importantly, despite a 12% sequence divergence between skeletal and S. pombe actin, S. pombe myosins Myo2 and Myo51 exhibited similar motile behavior with these two actins, validating key prior findings with these myosins that used skeletal actin.
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Affiliation(s)
- Qing Tang
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington VT
| | - Luther W. Pollard
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington VT
| | - Kaitlin E. Homa
- Molecular Genetics and Cell Biology, Biochemistry and Molecular Biology, the University of Chicago, Chicago, IL
| | - David R. Kovar
- Molecular Genetics and Cell Biology, Biochemistry and Molecular Biology, the University of Chicago, Chicago, IL
| | - Kathleen M. Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington VT
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18
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Esmaeilniakooshkghazi A, Pham E, George SP, Ahrorov A, Villagomez FR, Byington M, Mukhopadhyay S, Patnaik S, Conrad JC, Naik M, Ravi S, Tebbutt N, Mooi J, Reehorst CM, Mariadason JM, Khurana S. In colon cancer cells fascin1 regulates adherens junction remodeling. FASEB J 2023; 37:e22786. [PMID: 36786724 DOI: 10.1096/fj.202201454r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/21/2022] [Accepted: 01/10/2023] [Indexed: 02/15/2023]
Abstract
Adherens junctions (AJs) are a defining feature of all epithelial cells. They regulate epithelial tissue architecture and integrity, and their dysregulation is a key step in tumor metastasis. AJ remodeling is crucial for cancer progression, and it plays a key role in tumor cell survival, growth, and dissemination. Few studies have examined AJ remodeling in cancer cells consequently, it remains poorly understood and unleveraged in the treatment of metastatic carcinomas. Fascin1 is an actin-bundling protein that is absent from the normal epithelium but its expression in colon cancer is linked to metastasis and increased mortality. Here, we provide the molecular mechanism of AJ remodeling in colon cancer cells and identify for the first time, fascin1's function in AJ remodeling. We show that in colon cancer cells fascin1 remodels junctional actin and actomyosin contractility which makes AJs less stable but more dynamic. By remodeling AJs fascin1 drives mechanoactivation of WNT/β-catenin signaling and generates "collective plasticity" which influences the behavior of cells during cell migration. The impact of mechanical inputs on WNT/β-catenin activation in cancer cells remains poorly understood. Our findings highlight the role of AJ remodeling and mechanosensitive WNT/β-catenin signaling in the growth and dissemination of colorectal carcinomas.
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Affiliation(s)
| | - Eric Pham
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Sudeep P George
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Afzal Ahrorov
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Fabian R Villagomez
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Michael Byington
- Department of Chemical and Bimolecular Engineering, University of Houston, Houston, Texas, USA
| | - Srijita Mukhopadhyay
- Department of Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, Texas, USA
| | - Srinivas Patnaik
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Jacinta C Conrad
- Department of Chemical and Bimolecular Engineering, University of Houston, Houston, Texas, USA
| | - Monali Naik
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Saathvika Ravi
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA
| | - Niall Tebbutt
- Gastrointestinal Cancers Programs, Olivia Newton-John Cancer Research Institute, and La Trobe University School of Cancer Medicine, Melbourne, Victoria, Australia
| | - Jennifer Mooi
- Gastrointestinal Cancers Programs, Olivia Newton-John Cancer Research Institute, and La Trobe University School of Cancer Medicine, Melbourne, Victoria, Australia
| | - Camilla M Reehorst
- Gastrointestinal Cancers Programs, Olivia Newton-John Cancer Research Institute, and La Trobe University School of Cancer Medicine, Melbourne, Victoria, Australia
| | - John M Mariadason
- Gastrointestinal Cancers Programs, Olivia Newton-John Cancer Research Institute, and La Trobe University School of Cancer Medicine, Melbourne, Victoria, Australia
| | - Seema Khurana
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, USA.,School of Health Professions, Baylor College of Medicine, Houston, Texas, USA
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19
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Rajan S, Kudryashov DS, Reisler E. Actin Bundles Dynamics and Architecture. Biomolecules 2023; 13:450. [PMID: 36979385 PMCID: PMC10046292 DOI: 10.3390/biom13030450] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/04/2023] Open
Abstract
Cells use the actin cytoskeleton for many of their functions, including their division, adhesion, mechanosensing, endo- and phagocytosis, migration, and invasion. Actin bundles are the main constituent of actin-rich structures involved in these processes. An ever-increasing number of proteins that crosslink actin into bundles or regulate their morphology is being identified in cells. With recent advances in high-resolution microscopy and imaging techniques, the complex process of bundles formation and the multiple forms of physiological bundles are beginning to be better understood. Here, we review the physiochemical and biological properties of four families of highly conserved and abundant actin-bundling proteins, namely, α-actinin, fimbrin/plastin, fascin, and espin. We describe the similarities and differences between these proteins, their role in the formation of physiological actin bundles, and their properties-both related and unrelated to their bundling abilities. We also review some aspects of the general mechanism of actin bundles formation, which are known from the available information on the activity of the key actin partners involved in this process.
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Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
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20
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Daeden A, Mietke A, Derivery E, Seum C, Jülicher F, Gonzalez-Gaitan M. Polarized branched Actin modulates cortical mechanics to produce unequal-size daughters during asymmetric division. Nat Cell Biol 2023; 25:235-245. [PMID: 36747081 PMCID: PMC9928585 DOI: 10.1038/s41556-022-01058-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/22/2022] [Indexed: 02/08/2023]
Abstract
The control of cell shape during cytokinesis requires a precise regulation of mechanical properties of the cell cortex. Only few studies have addressed the mechanisms underlying the robust production of unequal-sized daughters during asymmetric cell division. Here we report that unequal daughter-cell sizes resulting from asymmetric sensory organ precursor divisions in Drosophila are controlled by the relative amount of cortical branched Actin between the two cell poles. We demonstrate this by mistargeting the machinery for branched Actin dynamics using nanobodies and optogenetics. We can thereby engineer the cell shape with temporal precision and thus the daughter-cell size at different stages of cytokinesis. Most strikingly, inverting cortical Actin asymmetry causes an inversion of daughter-cell sizes. Our findings uncover the physical mechanism by which the sensory organ precursor mother cell controls relative daughter-cell size: polarized cortical Actin modulates the cortical bending rigidity to set the cell surface curvature, stabilize the division and ultimately lead to unequal daughter-cell size.
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Affiliation(s)
- Alicia Daeden
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Alexander Mietke
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA, USA
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Center for Systems Biology Dresden, Dresden, Germany
| | - Emmanuel Derivery
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Carole Seum
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Marcos Gonzalez-Gaitan
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland.
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21
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Nast-Kolb T, Bleicher P, Payr M, Bausch AR. VASP localization to lipid bilayers induces polymerization driven actin bundle formation. Mol Biol Cell 2022; 33:ar91. [PMID: 35830600 PMCID: PMC9582628 DOI: 10.1091/mbc.e21-11-0577] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Actin bundles constitute important cytoskeleton structures and enable a scaffold for force transmission inside cells. Actin bundles are formed by proteins, with multiple F-actin binding domains cross-linking actin filaments to each other. Vasodilator-stimulated phosphoprotein (VASP) has mostly been reported as an actin elongator, but it has been shown to be a bundling protein as well and is found in bundled actin structures at filopodia and adhesion sites. Based on in vitro experiments, it remains unclear when and how VASP can act as an actin bundler or elongator. Here we demonstrate that VASP bound to membranes facilitates the formation of large actin bundles during polymerization. The alignment by polymerization requires the fluidity of the lipid bilayers. The mobility within the bilayer enables VASP to bind to filaments and capture and track growing barbed ends. VASP itself phase separates into a protein-enriched phase on the bilayer. This VASP-rich phase nucleates and accumulates at bundles during polymerization, which in turn leads to a reorganization of the underlying lipid bilayer. Our findings demonstrate that the nature of VASP localization is decisive for its function. The up-concentration based on VASP’s affinity to actin during polymerization enables it to simultaneously fulfill the function of an elongator and a bundler.
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Affiliation(s)
- T Nast-Kolb
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany and
| | - P Bleicher
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany and.,Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892
| | - M Payr
- Lehrstuhl für Biophysik E27, Physik-Department, Technische Universität München, Garching, Germany and.,Structural and Computational Biology Unit, EMBL Heidelberg, Meyerhoferstr. 1, 69117 Heidelberg, Germany
| | - A R Bausch
- Center for Protein Assemblies (CPA), Ernst-Otto-Fischer Str. 8, 85747 Garching, Germany
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22
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Bashirzadeh Y, Moghimianavval H, Liu AP. Encapsulated actomyosin patterns drive cell-like membrane shape changes. iScience 2022; 25:104236. [PMID: 35521522 PMCID: PMC9061794 DOI: 10.1016/j.isci.2022.104236] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 01/26/2022] [Accepted: 04/07/2022] [Indexed: 11/21/2022] Open
Abstract
Cell shape changes from locomotion to cytokinesis are, to a large extent, driven by myosin-driven remodeling of cortical actin patterns. Passive crosslinkers such as α-actinin and fascin as well as actin nucleator Arp2/3 complex largely determine actin network architecture and, consequently, membrane shape changes. Here we reconstitute actomyosin networks inside cell-sized lipid bilayer vesicles and show that depending on vesicle size and concentrations of α-actinin and fascin actomyosin networks assemble into ring and aster-like patterns. Anchoring actin to the membrane does not change actin network architecture yet exerts forces and deforms the membrane when assembled in the form of a contractile ring. In the presence of α-actinin and fascin, an Arp2/3 complex-mediated actomyosin cortex is shown to assemble a ring-like pattern at the equatorial cortex followed by myosin-driven clustering and consequently blebbing. An active gel theory unifies a model for the observed membrane shape changes induced by the contractile cortex.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Allen P. Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
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23
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Atherton J, Stouffer M, Francis F, Moores CA. Visualising the cytoskeletal machinery in neuronal growth cones using cryo-electron tomography. J Cell Sci 2022; 135:274968. [PMID: 35383828 PMCID: PMC9016625 DOI: 10.1242/jcs.259234] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 03/02/2022] [Indexed: 12/12/2022] Open
Abstract
Neurons extend axons to form the complex circuitry of the mature brain. This depends on the coordinated response and continuous remodelling of the microtubule and F-actin networks in the axonal growth cone. Growth cone architecture remains poorly understood at nanoscales. We therefore investigated mouse hippocampal neuron growth cones using cryo-electron tomography to directly visualise their three-dimensional subcellular architecture with molecular detail. Our data showed that the hexagonal arrays of actin bundles that form filopodia penetrate and terminate deep within the growth cone interior. We directly observed the modulation of these and other growth cone actin bundles by alteration of individual F-actin helical structures. Microtubules with blunt, slightly flared or gently curved ends predominated in the growth cone, frequently contained lumenal particles and exhibited lattice defects. Investigation of the effect of absence of doublecortin, a neurodevelopmental cytoskeleton regulator, on growth cone cytoskeleton showed no major anomalies in overall growth cone organisation or in F-actin subpopulations. However, our data suggested that microtubules sustained more structural defects, highlighting the importance of microtubule integrity during growth cone migration. Summary: Cryo-electron tomographic reconstruction of neuronal growth cone subdomains reveals distinctive F-actin and microtubule cytoskeleton architectures and modulation at molecular detail.
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Affiliation(s)
- Joseph Atherton
- Randall Centre for Cell and Molecular Biophysics, King's College, London SE1 1YR, UK.,Institute of Structural and Molecular Biology, Birkbeck, University of London, London WC1E 7HX, UK
| | - Melissa Stouffer
- INSERM UMR-S 1270, 17 Rue du Fer à Moulin, 75005 Paris, France.,Sorbonne University UMR-S 1270, 4 Place Jussieu, 75005 Paris, France.,Institut du Fer à Moulin, 17 Rue du Fer à Moulin, 75005 Paris, France.,Institute of Science and Technology Austria, Am campus 1, 3400 Klosterneuberg, Austria
| | - Fiona Francis
- INSERM UMR-S 1270, 17 Rue du Fer à Moulin, 75005 Paris, France.,Sorbonne University UMR-S 1270, 4 Place Jussieu, 75005 Paris, France.,Institut du Fer à Moulin, 17 Rue du Fer à Moulin, 75005 Paris, France
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Birkbeck, University of London, London WC1E 7HX, UK
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24
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Aranjuez GF, Kim J, Jewett TJ. The Chlamydia trachomatis Early Effector Tarp Outcompetes Fascin in Forming F-Actin Bundles In Vivo. Front Cell Infect Microbiol 2022; 12:811407. [PMID: 35300377 PMCID: PMC8921475 DOI: 10.3389/fcimb.2022.811407] [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: 11/08/2021] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
The intracellular pathogen Chlamydia trachomatis secretes multiple early effectors into the host cell to promote invasion. A key early effector during host cell entry, Tarp (translocated actin-recruiting phosphoprotein) is comprised of multiple protein domains known to have roles in cell signaling, G-actin nucleation and F-actin bundle formation. In vitro, the actin bundles generated by Tarp are uncharacteristically flexible, however, in vivo, the biological significance of Tarp-mediated actin bundles remains unknown. We hypothesize that Tarp's ability to generate unique actin bundles, in part, facilitates chlamydial entry into epithelial cells. To study the in vivo interaction between Tarp and F-actin, we transgenically expressed Tarp in Drosophila melanogaster tissues. Tarp expressed in Drosophila is phosphorylated and forms F-actin-enriched aggregates in tissues. To gain insight into the significance of Tarp actin bundles in vivo, we utilized the well-characterized model system of mechanosensory bristle development in Drosophila melanogaster. Tarp expression in wild type flies produced curved bristles, indicating a perturbation in F-actin dynamics during bristle development. Two F-actin bundlers, Singed/Fascin and Forked/Espin, are important for normal bristle shape. Surprisingly, Tarp expression in the bristles displaced Singed/Fascin away from F-actin bundles. Tarp's competitive behavior against Fascin during F-actin bundling was confirmed in vitro. Loss of either singed or forked in flies leads to highly deformed bristles. Strikingly, Tarp partially rescued the loss of singed, reducing the severity of the bristle morphology defect. This work provides in vivo confirmation of Tarp's F-actin bundling activity and further uncovers a competitive behavior against the host bundler Singed/Fascin during bundle assembly. Also, we demonstrate the utility of Drosophila melanogaster as an in vivo cell biological platform to study bacterial effector function.
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Affiliation(s)
- George F. Aranjuez
- Division of Immunity and Pathogenesis, Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
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25
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Abstract
The precise assembly and disassembly of actin filaments is required for several cellular processes, and their regulation has been scrutinized for decades. Twenty years ago, a handful of studies marked the advent of a new type of experiment to study actin dynamics: using optical microscopy to look at individual events, taking place on individual filaments in real time. Here, we summarize the main characteristics of this approach and how it has changed our ability to understand actin assembly dynamics. We also highlight some of its caveats and reflect on what we have learned over the past 20 years, leading us to propose a set of guidelines, which we hope will contribute to a better exploitation of this powerful tool.
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Sherer LA, Courtemanche N. Cooperative bundling by fascin generates actin structures with architectures that depend on filament length. Front Cell Dev Biol 2022; 10:974047. [PMID: 36120572 PMCID: PMC9479110 DOI: 10.3389/fcell.2022.974047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/12/2022] [Indexed: 11/30/2022] Open
Abstract
The assembly of actin-based structures with precisely defined architectures supports essential cellular functions, including motility, intracellular transport, and division. The geometric arrangements of the filaments within actin structures are stabilized via the association of crosslinking proteins, which bind two filaments simultaneously. Because actin polymerization and crosslinking occur concurrently within the dynamic environment of the cell, these processes likely play interdependent roles in shaping the architectures of actin-based structures. To dissect the contribution of polymerization to the construction of higher-order actin structures, we investigated how filament elongation affects the formation of simple, polarized actin bundles by the crosslinking protein fascin. Using populations of actin filaments to represent distinct stages of elongation, we found that the rate of bundle assembly increases with filament length. Fascin assembles short filaments into discrete bundles, whereas bundles of long filaments merge with one another to form interconnected networks. Although filament elongation promotes bundle coalescence, many connections formed between elongating bundles are short-lived and are followed by filament breakage. Our data suggest that initiation of crosslinking early in elongation aligns growing filaments, creating a template for continued bundle assembly as elongation proceeds. This initial alignment promotes the assembly of bundles that are resistant to large changes in curvature that are required for coalescence into interconnected networks. As a result, bundles of short filaments remain straighter and more topologically discrete as elongation proceeds than bundles assembled from long filaments. Thus, uncoordinated filament elongation and crosslinking can alter the architecture of bundled actin networks, highlighting the importance of maintaining precise control over filament length during the assembly of specialized actin structures.
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27
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Bashirzadeh Y, Redford SA, Lorpaiboon C, Groaz A, Moghimianavval H, Litschel T, Schwille P, Hocky GM, Dinner AR, Liu AP. Actin crosslinker competition and sorting drive emergent GUV size-dependent actin network architecture. Commun Biol 2021. [PMID: 34584211 DOI: 10.1101/2020.10.03.322354v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
The proteins that make up the actin cytoskeleton can self-assemble into a variety of structures. In vitro experiments and coarse-grained simulations have shown that the actin crosslinking proteins α-actinin and fascin segregate into distinct domains in single actin bundles with a molecular size-dependent competition-based mechanism. Here, by encapsulating actin, α-actinin, and fascin in giant unilamellar vesicles (GUVs), we show that physical confinement can cause these proteins to form much more complex structures, including rings and asters at GUV peripheries and centers; the prevalence of different structures depends on GUV size. Strikingly, we found that α-actinin and fascin self-sort into separate domains in the aster structures with actin bundles whose apparent stiffness depends on the ratio of the relative concentrations of α-actinin and fascin. The observed boundary-imposed effect on protein sorting may be a general mechanism for creating emergent structures in biopolymer networks with multiple crosslinkers.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Steven A Redford
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
- The graduate program in Biophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | | | - Alessandro Groaz
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | | | - Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Glen M Hocky
- Department of Chemistry, New York University, New York, NY, 10003, USA
| | - Aaron R Dinner
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.
- Department of Chemistry, University of Chicago, Chicago, IL, 60637, USA.
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Biophysics, University of Michigan, Ann Arbor, MI, 48109, USA.
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, 48109, USA.
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28
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Bashirzadeh Y, Redford SA, Lorpaiboon C, Groaz A, Moghimianavval H, Litschel T, Schwille P, Hocky GM, Dinner AR, Liu AP. Actin crosslinker competition and sorting drive emergent GUV size-dependent actin network architecture. Commun Biol 2021; 4:1136. [PMID: 34584211 PMCID: PMC8478941 DOI: 10.1038/s42003-021-02653-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/08/2021] [Indexed: 02/07/2023] Open
Abstract
The proteins that make up the actin cytoskeleton can self-assemble into a variety of structures. In vitro experiments and coarse-grained simulations have shown that the actin crosslinking proteins α-actinin and fascin segregate into distinct domains in single actin bundles with a molecular size-dependent competition-based mechanism. Here, by encapsulating actin, α-actinin, and fascin in giant unilamellar vesicles (GUVs), we show that physical confinement can cause these proteins to form much more complex structures, including rings and asters at GUV peripheries and centers; the prevalence of different structures depends on GUV size. Strikingly, we found that α-actinin and fascin self-sort into separate domains in the aster structures with actin bundles whose apparent stiffness depends on the ratio of the relative concentrations of α-actinin and fascin. The observed boundary-imposed effect on protein sorting may be a general mechanism for creating emergent structures in biopolymer networks with multiple crosslinkers. By encapsulating proteins in giant unilamellar vesicles, Bashirzadeh et al find that actin crosslinkers, α-actinin and fascin, can self-assemble with actin into complex structures that depend on the degree of confinement. Further analysis and modeling show that α-actinin and fascin sort to separate domains of these structures. These insights may be generalizable to other biopolymer networks containing crosslinkers.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Steven A Redford
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.,The graduate program in Biophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | | | - Alessandro Groaz
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | | | - Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Glen M Hocky
- Department of Chemistry, New York University, New York, NY, 10003, USA
| | - Aaron R Dinner
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA. .,Department of Chemistry, University of Chicago, Chicago, IL, 60637, USA.
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Biophysics, University of Michigan, Ann Arbor, MI, 48109, USA. .,Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, 48109, USA.
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29
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A strong nonequilibrium bound for sorting of cross-linkers on growing biopolymers. Proc Natl Acad Sci U S A 2021; 118:2102881118. [PMID: 34518221 DOI: 10.1073/pnas.2102881118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2021] [Indexed: 12/18/2022] Open
Abstract
Understanding the role of nonequilibrium driving in self-organization is crucial for developing a predictive description of biological systems, yet it is impeded by their complexity. The actin cytoskeleton serves as a paradigm for how equilibrium and nonequilibrium forces combine to give rise to self-organization. Motivated by recent experiments that show that actin filament growth rates can tune the morphology of a growing actin bundle cross-linked by two competing types of actin-binding proteins [S. L. Freedman et al., Proc. Natl. Acad. Sci. U.S.A. 116, 16192-16197 (2019)], we construct a minimal model for such a system and show that the dynamics of a growing actin bundle are subject to a set of thermodynamic constraints that relate its nonequilibrium driving, morphology, and molecular fluxes. The thermodynamic constraints reveal the importance of correlations between these molecular fluxes and offer a route to estimating microscopic driving forces from microscopy experiments.
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30
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Kadzik RS, Homa KE, Kovar DR. F-Actin Cytoskeleton Network Self-Organization Through Competition and Cooperation. Annu Rev Cell Dev Biol 2021; 36:35-60. [PMID: 33021819 DOI: 10.1146/annurev-cellbio-032320-094706] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many fundamental cellular processes such as division, polarization, endocytosis, and motility require the assembly, maintenance, and disassembly of filamentous actin (F-actin) networks at specific locations and times within the cell. The particular function of each network is governed by F-actin organization, size, and density as well as by its dynamics. The distinct characteristics of different F-actin networks are determined through the coordinated actions of specific sets of actin-binding proteins (ABPs). Furthermore, a cell typically assembles and uses multiple F-actin networks simultaneously within a common cytoplasm, so these networks must self-organize from a common pool of shared globular actin (G-actin) monomers and overlapping sets of ABPs. Recent advances in multicolor imaging and analysis of ABPs and their associated F-actin networks in cells, as well as the development of sophisticated in vitro reconstitutions of networks with ensembles of ABPs, have allowed the field to start uncovering the underlying principles by which cells self-organize diverse F-actin networks to execute basic cellular functions.
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Affiliation(s)
- Rachel S Kadzik
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA; , .,Department of Molecular BioSciences, Northwestern University, Evanston, Illinois 60208, USA;
| | - Kaitlin E Homa
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA; ,
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA; , .,Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA
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31
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Iv F, Martins CS, Castro-Linares G, Taveneau C, Barbier P, Verdier-Pinard P, Camoin L, Audebert S, Tsai FC, Ramond L, Llewellyn A, Belhabib M, Nakazawa K, Di Cicco A, Vincentelli R, Wenger J, Cabantous S, Koenderink GH, Bertin A, Mavrakis M. Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms. J Cell Sci 2021; 134:jcs258484. [PMID: 34350965 DOI: 10.1242/jcs.258484] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 07/02/2021] [Indexed: 01/22/2023] Open
Abstract
Septin GTP-binding proteins contribute essential biological functions that range from the establishment of cell polarity to animal tissue morphogenesis. Human septins in cells form hetero-octameric septin complexes containing the ubiquitously expressed SEPT9 subunit (also known as SEPTIN9). Despite the established role of SEPT9 in mammalian development and human pathophysiology, biochemical and biophysical studies have relied on monomeric SEPT9, thus not recapitulating its native assembly into hetero-octameric complexes. We established a protocol that enabled, for the first time, the isolation of recombinant human septin octamers containing distinct SEPT9 isoforms. A combination of biochemical and biophysical assays confirmed the octameric nature of the isolated complexes in solution. Reconstitution studies showed that octamers with either a long or a short SEPT9 isoform form filament assemblies, and can directly bind and cross-link actin filaments, raising the possibility that septin-decorated actin structures in cells reflect direct actin-septin interactions. Recombinant SEPT9-containing octamers will make it possible to design cell-free assays to dissect the complex interactions of septins with cell membranes and the actin and microtubule cytoskeleton.
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Affiliation(s)
- Francois Iv
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Carla Silva Martins
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Gerard Castro-Linares
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Cyntia Taveneau
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Australia; Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, 3800 Clayton, Australia
| | - Pascale Barbier
- Aix-Marseille Univ, CNRS, UMR 7051, Institut de Neurophysiopathologie (INP), 13005 Marseille, France
| | - Pascal Verdier-Pinard
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Luc Camoin
- Aix-Marseille Univ, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, Marseille, France
| | - Stéphane Audebert
- Aix-Marseille Univ, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, Marseille, France
| | - Feng-Ching Tsai
- Department of Living Matter, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Laurie Ramond
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Alex Llewellyn
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Mayssa Belhabib
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Koyomi Nakazawa
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Aurélie Di Cicco
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Renaud Vincentelli
- Architecture et Fonction des Macromolécules Biologiques (AFMB), CNRS UMR7257, Aix Marseille Univ, 13009 Marseille, France
| | - Jerome Wenger
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), Inserm, Université Paul Sabatier-Toulouse III, CNRS, 31037 Toulouse, France
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
- Department of Living Matter, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Aurélie Bertin
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
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32
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Adams G, López MP, Cartagena-Rivera AX, Waterman CM. Survey of cancer cell anatomy in nonadhesive confinement reveals a role for filamin-A and fascin-1 in leader bleb-based migration. Mol Biol Cell 2021; 32:1772-1791. [PMID: 34260278 PMCID: PMC8684732 DOI: 10.1091/mbc.e21-04-0174] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cancer cells migrating in confined microenvironments exhibit plasticity of migration modes. Confinement of contractile cells in a nonadhesive environment drives “leader bleb–based migration” (LBBM), morphologically characterized by a long bleb that points in the direction of movement separated from a cell body by a contractile neck. Although cells undergoing LBBM have been visualized within tumors, the organization of organelles and actin regulatory proteins mediating LBBM is unknown. We analyzed the localization of fluorescent organelle-specific markers and actin-associated proteins in human melanoma and osteosarcoma cells undergoing LBBM. We found that organelles from the endolysosomal, secretory, and metabolic systems as well as the vimentin and microtubule cytoskeletons localized primarily in the cell body, with some endoplasmic reticulum, microtubules, and mitochondria extending into the leader bleb. Overexpression of fluorescently tagged actin regulatory proteins showed that actin assembly factors localized toward the leader bleb tip, contractility regulators and cross-linkers in the cell body cortex and neck, and cross-linkers additionally throughout the leader bleb. Quantitative analysis showed that excess filamin-A and fascin-1 increased migration speed and persistence, while their depletion by small interfering RNA indicates a requirement in promoting cortical tension and pressure to drive LBBM. This indicates a critical role of specific actin crosslinkers in LBBM.
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Affiliation(s)
- Gregory Adams
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, and
| | | | - Alexander X Cartagena-Rivera
- Section on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - Clare M Waterman
- Cell and Developmental Biology Center, National Heart, Lung and Blood Institute, and
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33
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Scheff DR, Redford SA, Lorpaiboon C, Majumdar S, Dinner AR, Gardel ML. Actin filament alignment causes mechanical hysteresis in cross-linked networks. SOFT MATTER 2021; 17:5499-5507. [PMID: 33989373 PMCID: PMC8192476 DOI: 10.1039/d1sm00412c] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Cells dynamically control their material properties through remodeling of the actin cytoskeleton, an assembly of cross-linked networks and bundles formed from the biopolymer actin. We recently found that cross-linked networks of actin filaments reconstituted in vitro can exhibit adaptive behavior and thus serve as a model system to understand the underlying mechanisms of mechanical adaptation of the cytoskeleton. In these networks, training, in the form of applied shear stress, can induce asymmetry in the nonlinear elasticity. Here, we explore control over this mechanical hysteresis by tuning the concentration and mechanical properties of cross-linking proteins in both experimental and simulated networks. We find that this effect depends on two conditions: the initial network must exhibit nonlinear strain stiffening, and filaments in the network must be able to reorient during training. Hysteresis depends strongly and non-monotonically on cross-linker concentration, with a peak at moderate concentrations. In contrast, at low concentrations, where the network does not strain stiffen, or at high concentrations, where filaments are less able to rearrange, there is little response to training. Additionally, we investigate the effect of changing cross-linker properties and find that longer or more flexible cross-linkers enhance hysteresis. Remarkably plotting hysteresis against alignment after training yields a single curve regardless of the physical properties or concentration of the cross-linkers.
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Affiliation(s)
- Danielle R Scheff
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and Department of Physics, University of Chicago, Chicago, IL 60637, USA
| | - Steven A Redford
- Biophysical Sciences Graduate Program, University of Chicago, Chicago, IL 60637, USA and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | | | | | - Aaron R Dinner
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA and Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Margaret L Gardel
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA. and Department of Physics, University of Chicago, Chicago, IL 60637, USA and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
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34
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Castaneda N, Park J, Kang EH. Regulation of Actin Bundle Mechanics and Structure by Intracellular Environmental Factors. FRONTIERS IN PHYSICS 2021; 9:675885. [PMID: 34422787 PMCID: PMC8376200 DOI: 10.3389/fphy.2021.675885] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The mechanical and structural properties of actin cytoskeleton drive various cellular processes, including structural support of the plasma membrane and cellular motility. Actin monomers assemble into double-stranded helical filaments as well as higher-ordered structures such as bundles and networks. Cells incorporate macromolecular crowding, cation interactions, and actin-crosslinking proteins to regulate the organization of actin bundles. Although the roles of each of these factors in actin bundling have been well-known individually, how combined factors contribute to actin bundle assembly, organization, and mechanics is not fully understood. Here, we describe recent studies that have investigated the mechanisms of how intracellular environmental factors influence actin bundling. This review highlights the effects of macromolecular crowding, cation interactions, and actin-crosslinking proteins on actin bundle organization, structure, and mechanics. Understanding these mechanisms is important in determining in vivo actin biophysics and providing insights into cell physiology.
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Affiliation(s)
- Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, United States
| | - Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
- Department of Physics, University of Central Florida, Orlando, FL, United States
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35
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Litschel T, Kelley CF, Holz D, Adeli Koudehi M, Vogel SK, Burbaum L, Mizuno N, Vavylonis D, Schwille P. Reconstitution of contractile actomyosin rings in vesicles. Nat Commun 2021; 12:2254. [PMID: 33859190 PMCID: PMC8050101 DOI: 10.1038/s41467-021-22422-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 03/04/2021] [Indexed: 12/31/2022] Open
Abstract
One of the grand challenges of bottom-up synthetic biology is the development of minimal machineries for cell division. The mechanical transformation of large-scale compartments, such as Giant Unilamellar Vesicles (GUVs), requires the geometry-specific coordination of active elements, several orders of magnitude larger than the molecular scale. Of all cytoskeletal structures, large-scale actomyosin rings appear to be the most promising cellular elements to accomplish this task. Here, we have adopted advanced encapsulation methods to study bundled actin filaments in GUVs and compare our results with theoretical modeling. By changing few key parameters, actin polymerization can be differentiated to resemble various types of networks in living cells. Importantly, we find membrane binding to be crucial for the robust condensation into a single actin ring in spherical vesicles, as predicted by theoretical considerations. Upon force generation by ATP-driven myosin motors, these ring-like actin structures contract and locally constrict the vesicle, forming furrow-like deformations. On the other hand, cortex-like actin networks are shown to induce and stabilize deformations from spherical shapes. Cytoskeletal networks support and direct cell shape and guide intercellular transport, but relatively little is understood about the self-organization of cytoskeletal components on the scale of an entire cell. Here, authors use an in vitro system and observe the assembly of different types of actin networks and the condensation of membrane-bound actin into single rings.
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Affiliation(s)
- Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Charlotte F Kelley
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Danielle Holz
- Department of Physics, Lehigh University, Bethlehem, PA, USA
| | | | - Sven K Vogel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Laura Burbaum
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Naoko Mizuno
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | | | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
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36
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Weirich KL, Stam S, Munro E, Gardel ML. Actin bundle architecture and mechanics regulate myosin II force generation. Biophys J 2021; 120:1957-1970. [PMID: 33798565 DOI: 10.1016/j.bpj.2021.03.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 03/01/2021] [Accepted: 03/12/2021] [Indexed: 10/21/2022] Open
Abstract
The actin cytoskeleton is a soft, structural material that underlies biological processes such as cell division, motility, and cargo transport. The cross-linked actin filaments self-organize into a myriad of architectures, from disordered meshworks to ordered bundles, which are hypothesized to control the actomyosin force generation that regulates cell migration, shape, and adhesion. Here, we use fluorescence microscopy and simulations to investigate how actin bundle architectures with varying polarity, spacing, and rigidity impact myosin II dynamics and force generation. Microscopy reveals that mixed-polarity bundles formed by rigid cross-linkers support slow, bidirectional myosin II filament motion, punctuated by periods of stalled motion. Simulations reveal that these locations of stalled myosin motion correspond to sustained, high forces in regions of balanced actin filament polarity. By contrast, mixed-polarity bundles formed by compliant, large cross-linkers support fast, bidirectional motion with no traps. Simulations indicate that trap duration is directly related to force magnitude and that the observed increased velocity corresponds to lower forces resulting from both the increased bundle compliance and filament spacing. Our results indicate that the microstructures of actin assemblies regulate the dynamics and magnitude of myosin II forces, highlighting the importance of architecture and mechanics in regulating forces in biological materials.
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Affiliation(s)
- Kimberly L Weirich
- James Franck Institute, University of Chicago, Chicago, Illinois; Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois; Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina
| | - Samantha Stam
- Biophysical Sciences Graduate Program, University of Chicago, Chicago, Illinois; Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois; Department of Molecular and Cellular Biology, University of California, Davis, Davis, California
| | - Edwin Munro
- Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois; Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, Illinois
| | - Margaret L Gardel
- James Franck Institute, University of Chicago, Chicago, Illinois; Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois; Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois; Department of Physics, University of Chicago, Chicago, Illinois.
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37
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Liu R, Billington N, Yang Y, Bond C, Hong A, Siththanandan V, Takagi Y, Sellers JR. A binding protein regulates myosin-7a dimerization and actin bundle assembly. Nat Commun 2021; 12:563. [PMID: 33495456 PMCID: PMC7835385 DOI: 10.1038/s41467-020-20864-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 12/07/2020] [Indexed: 01/17/2023] Open
Abstract
Myosin-7a, despite being monomeric in isolation, plays roles in organizing actin-based cell protrusions such as filopodia, microvilli and stereocilia, as well as transporting cargoes within them. Here, we identify a binding protein for Drosophila myosin-7a termed M7BP, and describe how M7BP assembles myosin-7a into a motile complex that enables cargo translocation and actin cytoskeletal remodeling. M7BP binds to the autoinhibitory tail of myosin-7a, extending the molecule and activating its ATPase activity. Single-molecule reconstitution show that M7BP enables robust motility by complexing with myosin-7a as 2:2 translocation dimers in an actin-regulated manner. Meanwhile, M7BP tethers actin, enhancing complex’s processivity and driving actin-filament alignment during processive runs. Finally, we show that myosin-7a-M7BP complex assembles actin bundles and filopodia-like protrusions while migrating along them in living cells. Together, these findings provide insights into the mechanisms by which myosin-7a functions in actin protrusions. Myosin-7a is found in actin bundles, microvilli and stereocilia, and plays conserved roles in hearing and vision. Here the authors identify M7BP, a myosin-7a binding protein that activates and dimerizes myosin-7a, enabling cargo transport and assembly of actin bundles and filopodia-like protrusions
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Affiliation(s)
- Rong Liu
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Neil Billington
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yi Yang
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.,Laboratory of Functional Proteomics, College of Veterinary Medicine, Hunan Agricultural University, 410128, Changsha, Hunan, China
| | - Charles Bond
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Amy Hong
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Verl Siththanandan
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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38
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Ljubojevic N, Henderson JM, Zurzolo C. The Ways of Actin: Why Tunneling Nanotubes Are Unique Cell Protrusions. Trends Cell Biol 2020; 31:130-142. [PMID: 33309107 DOI: 10.1016/j.tcb.2020.11.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/09/2020] [Accepted: 11/16/2020] [Indexed: 12/22/2022]
Abstract
Actin remodeling is at the heart of the response of cells to external or internal stimuli, allowing a variety of membrane protrusions to form. Fifteen years ago, tunneling nanotubes (TNTs) were identified, bringing a novel addition to the family of actin-supported cellular protrusions. Their unique property as conduits for cargo transfer between distant cells emphasizes the unique nature of TNTs among other protrusions. While TNTs in different pathological and physiological scenarios have been described, the molecular basis of how TNTs form is not well understood. In this review, we discuss the role of several actin regulators in the formation of TNTs and suggest potential players based on their comparison with other actin-based protrusions. New perspectives for discovering a distinct TNT formation pathway would enable us to target them in treating the increasing number of TNT-involved pathologies.
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Affiliation(s)
- Nina Ljubojevic
- Membrane Traffic and Pathogenesis, Institut Pasteur, UMR3691 CNRS, 75015 Paris, France; Sorbonne Université, ED394 - Physiologie, Physiopathologie et Thérapeutique, 75005 Paris, France
| | - J Michael Henderson
- Membrane Traffic and Pathogenesis, Institut Pasteur, UMR3691 CNRS, 75015 Paris, France; Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 75005 Paris, France
| | - Chiara Zurzolo
- Membrane Traffic and Pathogenesis, Institut Pasteur, UMR3691 CNRS, 75015 Paris, France.
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39
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Bashirzadeh Y, Wubshet NH, Liu AP. Confinement Geometry Tunes Fascin-Actin Bundle Structures and Consequently the Shape of a Lipid Bilayer Vesicle. Front Mol Biosci 2020; 7:610277. [PMID: 33240934 PMCID: PMC7680900 DOI: 10.3389/fmolb.2020.610277] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 10/20/2020] [Indexed: 12/27/2022] Open
Abstract
Depending on the physical and biochemical properties of actin-binding proteins, actin networks form different types of membrane protrusions at the cell periphery. Actin crosslinkers, which facilitate the interaction of actin filaments with one another, are pivotal in determining the mechanical properties and protrusive behavior of actin networks. Short crosslinkers such as fascin bundle F-actin to form rigid spiky filopodial protrusions. By encapsulation of fascin and actin in giant unilamellar vesicles (GUVs), we show that fascin-actin bundles cause various GUV shape changes by forming bundle networks or straight single bundles depending on GUV size and fascin concentration. We also show that the presence of a long crosslinker, α-actinin, impacts fascin-induced GUV shape changes and significantly impairs the formation of filopodia-like protrusions. Actin bundle-induced GUV shape changes are confirmed by light-induced disassembly of actin bundles leading to the reversal of GUV shape. Our study contributes to advancing the design of shape-changing minimal cells for better characterization of the interaction between lipid bilayer membranes and actin cytoskeleton.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Nadab H. Wubshet
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Allen P. Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Biophysics, University of Michigan, Ann Arbor, MI, United States
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, United States
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40
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Park J, Lee M, Lee B, Castaneda N, Tetard L, Kang EH. Crowding tunes the organization and mechanics of actin bundles formed by crosslinking proteins. FEBS Lett 2020; 595:26-40. [PMID: 33020904 DOI: 10.1002/1873-3468.13949] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 01/05/2023]
Abstract
Fascin and α-actinin form higher-ordered actin bundles that mediate numerous cellular processes including cell morphogenesis and movement. While it is understood crosslinked bundle formation occurs in crowded cytoplasm, how crowding affects the bundling activities of the two crosslinking proteins is not known. Here, we demonstrate how solution crowding modulates the organization and mechanical properties of fascin- and α-actinin-induced bundles, utilizing total internal reflection fluorescence and atomic force microscopy imaging. Molecular dynamics simulations support the inference that crowding reduces binding interaction between actin filaments and fascin or the calponin homology 1 domain of α-actinin evidenced by interaction energy and hydrogen bonding analysis. Based on our findings, we suggest a mechanism of crosslinked actin bundle assembly and mechanics in crowded intracellular environments.
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Affiliation(s)
- Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA
| | - Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Briana Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
| | - Laurene Tetard
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
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41
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Kelley CA, Triplett O, Mallick S, Burkewitz K, Mair WB, Cram EJ. FLN-1/filamin is required to anchor the actomyosin cytoskeleton and for global organization of sub-cellular organelles in a contractile tissue. Cytoskeleton (Hoboken) 2020; 77:379-398. [PMID: 32969593 DOI: 10.1002/cm.21633] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 09/11/2020] [Accepted: 09/17/2020] [Indexed: 01/01/2023]
Abstract
Actomyosin networks are organized in space, direction, size, and connectivity to produce coordinated contractions across cells. We use the C. elegans spermatheca, a tube composed of contractile myoepithelial cells, to study how actomyosin structures are organized. FLN-1/filamin is required for the formation and stabilization of a regular array of parallel, contractile, actomyosin fibers in this tissue. Loss of fln-1 results in the detachment of actin fibers from the basal surface, which then accumulate along the cell junctions and are stabilized by spectrin. In addition, actin and myosin are captured at the nucleus by the linker of nucleoskeleton and cytoskeleton complex (LINC) complex, where they form large foci. Nuclear positioning and morphology, distribution of the endoplasmic reticulum and the mitochondrial network are also disrupted. These results demonstrate that filamin is required to prevent large actin bundle formation and detachment, to prevent excess nuclear localization of actin and myosin, and to ensure correct positioning of organelles.
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Affiliation(s)
- Charlotte A Kelley
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Olivia Triplett
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Samyukta Mallick
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| | - Kristopher Burkewitz
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts, USA.,Department of Cell and Developmental Biology, Vanderbilt School of Medicine, Nashville, Tennessee, USA
| | - William B Mair
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Erin J Cram
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
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42
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Involvement of Actin and Actin-Binding Proteins in Carcinogenesis. Cells 2020; 9:cells9102245. [PMID: 33036298 PMCID: PMC7600575 DOI: 10.3390/cells9102245] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/18/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
The actin cytoskeleton plays a crucial role in many cellular processes while its reorganization is important in maintaining cell homeostasis. However, in the case of cancer cells, actin and ABPs (actin-binding proteins) are involved in all stages of carcinogenesis. Literature has reported that ABPs such as SATB1 (special AT-rich binding protein 1), WASP (Wiskott-Aldrich syndrome protein), nesprin, and villin take part in the initial step of carcinogenesis by regulating oncogene expression. Additionally, changes in actin localization promote cell proliferation by inhibiting apoptosis (SATB1). In turn, migration and invasion of cancer cells are based on the formation of actin-rich protrusions (Arp2/3 complex, filamin A, fascin, α-actinin, and cofilin). Importantly, more and more scientists suggest that microfilaments together with the associated proteins mediate tumor vascularization. Hence, the presented article aims to summarize literature reports in the context of the potential role of actin and ABPs in all steps of carcinogenesis.
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43
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Krippner S, Winkelmeier J, Knerr J, Brandt DT, Virant D, Schwan C, Endesfelder U, Grosse R. Postmitotic expansion of cell nuclei requires nuclear actin filament bundling by α-actinin 4. EMBO Rep 2020; 21:e50758. [PMID: 32959960 PMCID: PMC7645226 DOI: 10.15252/embr.202050758] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/13/2022] Open
Abstract
The actin cytoskeleton operates in a multitude of cellular processes including cell shape and migration, mechanoregulation, and membrane or organelle dynamics. However, its filamentous properties and functions inside the mammalian cell nucleus are less well explored. We previously described transient actin assembly at mitotic exit that promotes nuclear expansion during chromatin decondensation. Here, we identify non‐muscle α‐actinin 4 (ACTN4) as a critical regulator to facilitate F‐actin reorganization and bundling during postmitotic nuclear expansion. ACTN4 binds to nuclear actin filament structures, and ACTN4 clusters associate with nuclear F‐actin in a highly dynamic fashion. ACTN4 but not ACTN1 is required for proper postmitotic nuclear volume expansion, mediated by its actin‐binding domain. Using super‐resolution imaging to quantify actin filament numbers and widths in individual nuclei, we find that ACTN4 is necessary for postmitotic nuclear actin reorganization and actin filament bundling. Our findings uncover a nuclear cytoskeletal function for ACTN4 to control nuclear size and chromatin organization during mitotic cell division.
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Affiliation(s)
- Sylvia Krippner
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany
| | - Jannik Winkelmeier
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Julian Knerr
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany
| | | | - David Virant
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Carsten Schwan
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany
| | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Robert Grosse
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany.,Centre for Integrative Biological Signalling Studies, Freiburg, Germany
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44
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Boiero Sanders M, Antkowiak A, Michelot A. Diversity from similarity: cellular strategies for assigning particular identities to actin filaments and networks. Open Biol 2020; 10:200157. [PMID: 32873155 PMCID: PMC7536088 DOI: 10.1098/rsob.200157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The actin cytoskeleton has the particularity of being assembled into many functionally distinct filamentous networks from a common reservoir of monomeric actin. Each of these networks has its own geometrical, dynamical and mechanical properties, because they are capable of recruiting specific families of actin-binding proteins (ABPs), while excluding the others. This review discusses our current understanding of the underlying molecular mechanisms that cells have developed over the course of evolution to segregate ABPs to appropriate actin networks. Segregation of ABPs requires the ability to distinguish actin networks as different substrates for ABPs, which is regulated in three different ways: (1) by the geometrical organization of actin filaments within networks, which promotes or inhibits the accumulation of ABPs; (2) by the identity of the networks' filaments, which results from the decoration of actin filaments with additional proteins such as tropomyosin, from the use of different actin isoforms or from covalent modifications of actin; (3) by the existence of collaborative or competitive binding to actin filaments between two or multiple ABPs. This review highlights that all these effects need to be taken into account to understand the proper localization of ABPs in cells, and discusses what remains to be understood in this field of research.
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Affiliation(s)
- Micaela Boiero Sanders
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Adrien Antkowiak
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Alphée Michelot
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
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45
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RSU-1 Maintains Integrity of Caenorhabditis elegans Vulval Muscles by Regulating α-Actinin. G3-GENES GENOMES GENETICS 2020; 10:2507-2517. [PMID: 32461202 PMCID: PMC7341117 DOI: 10.1534/g3.120.401185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Egg-laying behavior in Caenorhabditis elegans is a well-known model for investigating fundamental cellular processes. In egg-laying, muscle contraction is the relaxation of the vulval muscle to extrude eggs from the vulva. Unlike skeletal muscle, vulval muscle lacks visible striations of the sarcomere. Therefore, vulval muscle must counteract the mechanical stress, caused by egg extrusion and body movement, from inducing cell-shape distortion by maintaining its cytoskeletal integrity. However, the underlying mechanisms that regulate the cellular integrity in vulval muscles remain unclear. Here, we demonstrate that C. elegans egg-laying requires proper vulval muscle 1 (vm1), in which the actin bundle organization of vm1 muscles is regulated by Ras suppressor protein 1 (RSU-1). In the loss of RSU-1, as well as RasLET-60 overactivation, blister-like membrane protrusions and disorganized actin bundles were observed in the vm1 muscles. Moreover, RasLET-60 depletion diminished the defected actin-bundles in rsu-1 mutant. These results reveal the genetic interaction of RSU-1 and RasLET-60 in vivo In addition, our results further demonstrated that the fifth to seventh leucine-rich region of RSU-1 is required to promote actin-bundling protein, α-actinin, for actin bundle stabilization in the vm1 muscles. This expands our understanding of the molecular mechanisms of actin bundle organization in a specialized smooth muscle.
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46
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Kinesin-14 motors drive a right-handed helical motion of antiparallel microtubules around each other. Nat Commun 2020; 11:2565. [PMID: 32444784 PMCID: PMC7244531 DOI: 10.1038/s41467-020-16328-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 04/08/2020] [Indexed: 12/30/2022] Open
Abstract
Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle. Some kinesins exhibit off-axis power strokes but their impact on motility and force generation in microtubule overlaps has not been investigated so far. Here authors use a 3D in vitro motility assay and find that Ndc’s off-axis motor forces generate torque in antiparallel microtubules which causes microtubule twisting and coiling.
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47
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Pfisterer K, Levitt J, Lawson CD, Marsh RJ, Heddleston JM, Wait E, Ameer-Beg SM, Cox S, Parsons M. FMNL2 regulates dynamics of fascin in filopodia. J Cell Biol 2020; 219:e201906111. [PMID: 32294157 PMCID: PMC7199847 DOI: 10.1083/jcb.201906111] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/30/2019] [Accepted: 02/20/2020] [Indexed: 12/31/2022] Open
Abstract
Filopodia are peripheral F-actin-rich structures that enable cell sensing of the microenvironment. Fascin is an F-actin-bundling protein that plays a key role in stabilizing filopodia to support efficient adhesion and migration. Fascin is also highly up-regulated in human cancers, where it increases invasive cell behavior and correlates with poor patient prognosis. Previous studies have shown that fascin phosphorylation can regulate F-actin bundling, and that this modification can contribute to subcellular fascin localization and function. However, the factors that regulate fascin dynamics within filopodia remain poorly understood. In the current study, we used advanced live-cell imaging techniques and a fascin biosensor to demonstrate that fascin phosphorylation, localization, and binding to F-actin are highly dynamic and dependent on local cytoskeletal architecture in cells in both 2D and 3D environments. Fascin dynamics within filopodia are under the control of formins, and in particular FMNL2, that binds directly to dephosphorylated fascin. Our data provide new insight into control of fascin dynamics at the nanoscale and into the mechanisms governing rapid cytoskeletal adaptation to environmental changes. This filopodia-driven exploration stage may represent an essential regulatory step in the transition from static to migrating cancer cells.
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Affiliation(s)
- Karin Pfisterer
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
| | - James Levitt
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
- Microscopy Innovation Centre, King's College London, Guy's Campus, London, UK
| | - Campbell D. Lawson
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
| | - Richard J. Marsh
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
| | - John M. Heddleston
- Advanced Imaging Centre, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA
| | - Eric Wait
- Advanced Imaging Centre, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA
| | - Simon Morris Ameer-Beg
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
- School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Campus, London, UK
| | - Susan Cox
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
| | - Maddy Parsons
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
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48
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Scholz M, Weirich KL, Gardel ML, Dinner AR. Tuning molecular motor transport through cytoskeletal filament network organization. SOFT MATTER 2020; 16:2135-2140. [PMID: 32016200 DOI: 10.1039/c9sm01904a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Within cells, crosslinking proteins organize cytoskeletal filaments both temporally and spatially to create dynamic and structurally diverse networks. Molecular motors move on these networks for both force generation and transport processes. How the transport statistics depend on the network architecture remains poorly characterized. Using cross-linking proteins (α-actinin, fimbrin, fascin, or filamin) and purified actin, we create cytoskeletal networks with diverse microscopic architectures. We track the motion of myosin II motor proteins moving on these networks and calculate transport statistics. We observe that motor dynamics change predictably based on the bundling of filaments within the underlying networks and discuss implications for network function.
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Affiliation(s)
- Monika Scholz
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA. and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Kimberly L Weirich
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA. and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Margaret L Gardel
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA. and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA and Department of Physics, The University of Chicago, Chicago, IL 60637, USA
| | - Aaron R Dinner
- James Franck Institute, The University of Chicago, Chicago, IL 60637, USA. and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA and Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA
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49
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Mancl JM, Suarez C, Liang WG, Kovar DR, Tang WJ. Pseudomonas aeruginosa exoenzyme Y directly bundles actin filaments. J Biol Chem 2020; 295:3506-3517. [PMID: 32019868 DOI: 10.1074/jbc.ra119.012320] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/23/2020] [Indexed: 11/06/2022] Open
Abstract
Pseudomonas aeruginosa uses a type III secretion system (T3SS) to inject cytotoxic effector proteins into host cells. The promiscuous nucleotidyl cyclase, exoenzyme Y (ExoY), is one of the most common effectors found in clinical P. aeruginosa isolates. Recent studies have revealed that the nucleotidyl cyclase activity of ExoY is stimulated by actin filaments (F-actin) and that ExoY alters actin cytoskeleton dynamics in vitro, via an unknown mechanism. The actin cytoskeleton plays an important role in numerous key biological processes and is targeted by many pathogens to gain competitive advantages. We utilized total internal reflection fluorescence microscopy, bulk actin assays, and EM to investigate how ExoY impacts actin dynamics. We found that ExoY can directly bundle actin filaments with high affinity, comparable with eukaryotic F-actin-bundling proteins, such as fimbrin. Of note, ExoY enzymatic activity was not required for F-actin bundling. Bundling is known to require multiple actin-binding sites, yet small-angle X-ray scattering experiments revealed that ExoY is a monomer in solution, and previous data suggested that ExoY possesses only one actin-binding site. We therefore hypothesized that ExoY oligomerizes in response to F-actin binding and have used the ExoY structure to construct a dimer-based structural model for the ExoY-F-actin complex. Subsequent mutational analyses suggested that the ExoY oligomerization interface plays a crucial role in mediating F-actin bundling. Our results indicate that ExoY represents a new class of actin-binding proteins that modulate the actin cytoskeleton both directly, via F-actin bundling, and indirectly, via actin-activated nucleotidyl cyclase activity.
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Affiliation(s)
- Jordan M Mancl
- Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637
| | - Cristian Suarez
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
| | - Wenguang G Liang
- Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
| | - Wei-Jen Tang
- Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637.
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50
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Matsuda K, Sugawa M, Yamagishi M, Kodera N, Yajima J. Visualizing dynamic actin cross‐linking processes driven by the actin‐binding protein anillin. FEBS Lett 2019; 594:1237-1247. [DOI: 10.1002/1873-3468.13720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/26/2019] [Accepted: 12/09/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Kyohei Matsuda
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
| | - Mitsuhiro Sugawa
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
- Komaba Institute for Science The University of Tokyo Japan
| | - Masahiko Yamagishi
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
- Komaba Institute for Science The University of Tokyo Japan
| | - Noriyuki Kodera
- Nano Life Science Institute (WPI‐NanoLSI) Kanazawa University Japan
| | - Junichiro Yajima
- Department of Life Sciences Graduate School of Arts and Sciences The University of Tokyo Japan
- Komaba Institute for Science The University of Tokyo Japan
- Research Center for Complex Systems Biology The University of Tokyo Japan
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